5 journal of sustainable architecture and civil engineering 2016/3/16 guest editor preface it is with a great pleasure that i preface this special issue of the journal of sustainable architecture and civil engineering, which comprises invited papers submitted to the 5th international conference on renewable energy sources & energy efficiency, organized in may 2016 in nicosia, cyprus. the 5th international conference on renewable energy sources & energy efficiency was organized on the 5th and 6th of may 2016 in cyprus by the cyprus chamber of commerce and industry, the 1927 founded union of cypriot businessmen, with a membership of 8,000 enterprises and 140 professional associations. since 2007, this biannual international conference is organized with great success and constitutes a very important venue of exchange of experiences, transfer of new knowledge in the field of energy. the conference aims at bringing together all the key stakeholders interested in renewable energy sources, energy efficiency and conventional fuels: industrial experts, academic researchers, policy makers and regulators. the thematic areas of the conference focus on the main topics of the sustainable built environment, including the fields of renewable energy sources and system integration, energy efficiency and policy, and the education and research in energy and environment. the topics of the international conference on renewable energy sources & energy efficiency are in line with the scopes of the journal of sustainable architecture and civil engineering, dealing with interdisciplinary fields of civil engineering, architecture and sustainability research with the aim to foster the integrated research of civil engineering and architecture targeted to promote sustainability. this special issue includes eight high quality invited studies, which cover a wide range of subjects which concern the sustainable built environment scientific community. particularly this issue focuses on the field of experimental and computational building physics, with emphases on the thermophysical performance of contemporary and innovative building elements. the invited studies also cover aspects of economic evaluation of energy retrofit projects, as well as social aspects of the energy behavioural change anticipated to enable the implementation of the ambitious european target of nearly zero energy buildings. state of the art approaches in the sustainable built environment including bim, lca and fragility analysis methods are also covered in this issue. the included studies concern both contemporary as well as traditional buildings of the southern european environment. one study “improving particle size distribution in cement paste by blending with superfine cement” included in this special issue was presented in the 5th international conference advanced construction 2016, kaunas, lithuania. taking this opportunity i would like to thank professor lina seduikyte for her continuous support towards publishing this special issue, professors ioannis michaelides and agis papadopoulos, executive and scientific chairmen of the 5th international conference on renewable energy sources & energy efficiency, who enabled with their targeted actions this publication and ms angeliki kylili for her valuable editorial and managerial support. this issue is anticipated to strengthen the scientific ties between the cypriot, the greek and the lithuanian research community, leading into further scientific collaborations within joint research initiatives. dr.-ing. paris a. fokaides guest editor school of engineering, frederick university, cyprus journal of sustainable architecture and civil engineering 2017/4/21 90 review of the book by allan t. shulman and randolph c. henning „the discipline of nature: alfred browning parker architect in florida“ journal of sustainable architecture and civil engineering vol. 4 / no. 21 / 2017 pp. 90-91 © kaunas university of technology review of the book by allan t. shulman and randolph c. henning jsace 4/21 jūratė kamičaitytė-virbašienė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania *corresponding author: jurate.kamicaityte@ktu.lt the book “the discipline of nature: alfred browning parker architect in florida” presents works and life of a prominent american architect alfred browning parker on the occasion of the 100th anniversary of his birth. it consists of the detailed description of the different periods of the architect‘s professional life; the memories of randolph c. henning, the author of the monograph about the works of alfred browning parker; excerpt from alfred browning parker office profile; and numerous sketches and photos of the projects. the philosophy and specificity of alfred browning parker works is very clearly described by allan t. shulman. part i explains how parker came to a paradigm for an architectural discipline derived from nature and it also presents five main principles of his work. part ii describes parker’s early career which had an important influence on the development of the suburban residential houses and public buildings (schools). part iii elucidates the development of parker’s philosophy – an organic approach that involves testing the boundaries between the modern and regional design and proposing various types of houses. part iv presents the application of parker’s organic principles on commercial and civic objects and at the scale of urban spaces. part v describes parker’s final insights and achievements of his activity seeking harmonious relationship between the human creation and the environment. the text is illustrated by numerous pictures of the parker’s projects. the book captures attention and is well structured, circumstantially and consistently telling the story of the architect’s life. it also presents philosophical and ideological statements of sustainable development in the architectural design and urban planning both from historical (vitruvius, the ten books on architecture) and today’s relevance point of view, such as: “build strongly; build as directly as possible with no complications; use the materials at hand and keep these as few as you can; let your building love its site and glorify its climate; design for use – make it beautiful.”, “(…) man must constantly seek to live harmoniously in his environment. he must be a conservationist of both human and material resources.”, “(…) we need much less of “look at me” construction.”, etc. 91 journal of sustainable architecture and civil engineering 2017/4/21 in conclusion, it is certainly a valuable and interesting book not only as the book presenting the biography of the famous architect but also as the book presenting the main principles of sustainable and “good” architecture. it can even be considered as an ethical and professional guide both for the students of architecture and practicing architects. allan t. shulman and randolph c. henning „the discipline of nature: alfred browning parker architect in florida” historymiami museum, 2016, isbn 978-0-9896815-9-9, p. 105. jūratė kamičaitytė-virbašienė professor kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research area landscape visual quality analysis, evaluation and regulation, methods of planned activity or object visual impact assessment, analysis of social preferences evaluating landscape visual quality and use of the analysis results in territory planning, evaluation of the potential of urban structures, research of cityscape identity, expression of sustainable development conception in architecture, landscape architecture, town and territory planning. address studentu st. 48, lt-51367 kaunas, lithuania tel. +37061477082 e-mail: jurate.kamicaityte@ktu.lt about the author 99 journal of sustainable architecture and civil engineering 2015/1/10 jsace 1/10 review of the book by richard garber journal of sustainable architecture and civil engineering vol. 1 / no. 10 / 2015 pp. 99-100 © kaunas university of technology gintaris cinelis kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania *corresponding author: g.cinelis@ktu.lt review of the book by richard garber “bim design. realising the creative potential of building information modelling” the focus of newly published book “bim design. realising the creative potential of building information modelling” is building information modeling (bim) the dynamically arising topic of nowadays. the popularity and importance of the abbreviation bim is becoming no less significant than that of the acronym cad at the junction of the last two decades of the previous century. “bim design. realising the creative potential of building information modelling” is a captivating work. two and a half hundred of pages include 181 images (coloured, monochrome illustrations, and diagrams), the table of contents, 35 items of selected bibliography, and a broad list of indexed references on 5 pages. each chapter provides the list of references named notes as well as the list of images. the book includes 8 numbered chapters and 7 named chapters presented as the case studies. the acknowledgement, dedication and foreword written by mario carpo can also be found in the book. the design of the book is stylistically attractive for the reader. the fact that there are many articles, essays, conference proceedings, also live debates among the web-based professional groups shows that building information modelling is one of the most widely discussed issue in the field of architectural design and construction. however, the lack of essential books substantively representing bim can be felt. in my opinion at least two aspects can be clearly identified while reading the book. the first one concerns the organization and logical structure of the work. the material appears by turns as methodological therefore more theoretic (numbered chapters) and as the case studies therefore more practical (named chapters). anyway, a big part of analysis of the bim problems is done as the case study analysis of various experiences of the advanced companies of the world but with the special emphasis to generative design experience, creative use of parametric geometries, environmental performance simulations and managing of construction and fabrication operations. journal of sustainable architecture and civil engineering 2015/1/10 100 the cases are chosen by the author as the specific ones each of them revealing different features of bim and digital technologies starting from the historical references in the early renaissance and ending with the contemporary concepts of knowledge architecture and life-cycle strategy. each case study in some way reflects any of bim methodical issues. the other aspect concerns the role of architects and their growing potential via the use of bim as the concept and the technological system that is able to put more control, sustainability and reliability in the processes and results of both design and construction. successful interdisciplinary collaboration between different teams and companies is a critical issue. the reflection of the problems mentioned above can be foreseen in the title of the book. the book extends the notion that architectural design is a rather disembodied process of aesthetic creation, and it also advocates holistic concept of architecture. this can be understood as general lineage of the work. generally, the influence of contemporary information technology as a multi-faceted and universal phenomenon to architecture and construction are very different but the author discovers the most important influences that aim to reunit design and making and close the gap between design intentions and project delivery, in the name of bim invite a new business model as well as a new legal framework for project delivery proclaiming new collaborative digital culture and possibly in the same time transforming the conception of authorship. on one hand, the author is concerned about the success of implementation of creative idea. on the other hand, he talks about the urgent need and inevitability of interdisciplinary collaboration. consequently, the book proclaims a new architectural paradigm defined as “actualization”, which tends to integrate design, construction and the use of products on the basis of digital platform substituting the old paradigm “representation” that becomes limited. finally, the author discusses the importance of participation in the investment cycle of bim of the new types of experts like bim managers, and also software developers, primarily because integration between various new platforms is becoming more and more necessary in the field of architecture, engineering and construction (aec) industry. this is only the beginning of a long distance run related to building information modeling, interrelations between the parts of it, and consideration of consequences relating society. although the book gives a good reflection of the state-of-the-art in the field, some important questions such as achievements and problems of data exchange and issues of the supply chain in the construction industry could be disclosed in a wider extent. there are also at least two additional evident and interesting problems of bim which deserve more attention. not every form and structure is possible to create as a parametric precise native adequately detailed instance of the model what in reality leads to controversial solutions of hybrid models consisting of various types not associated objects. the other often discussed question is how we can define and estimate the size and complexity of the building that is appropriate to design and construct using the new bim methodology. the aim of the book is not to teach definite methods of implementing specific procedures but mainly to provide knowledge and to make some impact on the reader’s thinking and understanding of. this is the reason for the usage of some particular illustrations that support the statements of the book. i believe the intention of the author was fulfilled. the book covered bim topic with a rich content and numerous examples. the work is well-written and easy to comprehend. the terms and keywords in italic can be characterized as conventional and understandable for experts. the referencing and gintaris cinelis associated professor faculty of civil engineering and architecture, kaunas university of technology address studentų st. 48, lt – 3031 kaunas, lithuania tel. +370 687 98 786 e-mail: g.cinelis@ktu.lt about the author documentation of sources used are accurate. the illustrations (photos, renderings and diagrams) are of a very good quality and easily readable. the book can serve as the essential reference not only for architecture and both structural and civil engineering students, but also for students of related study programmes. richard garber “bim design. realising the creative potential of building information modelling. john wiley & sons ltd, 2014, isbn 978-1-118-71980-0, pp. 248, (executive editor helen castle) journal of sustainable architecture and civil engineering 2017/1/18 50 *corresponding author: rutagarbaliauskaite@gmail.com transformation of protected urban landscapes http://dx.doi.org/10.5755/j01.sace.18.1.16260 rūta garbaliauskaitė, aušra mlinkauskienė kaunas university of technology, department of architecture and urbanistics studentų str. 48, kaunas, lithuania received 2016/09/19 accepted after revision 2016/02/02 journal of sustainable architecture and civil engineering vol. 1 / no. 18 / 2017 pp. 50-56 doi 10.5755/j01.sace.18.1.16260 © kaunas university of technology transformation of protected urban landscapes jsace 1/18 protected urban landscapes are usually perceived as old parts of a town or old towns. such historical hubs are found in vilnius, kaunas, klaipėda, kėdainiai and other towns in lithuania. perhaps such landscapes can be found in each state of european or the world; the most valuable are included into the unesco world heritage list. history of these cities or towns lasts for centuries; however, even on these territories the transformation as a process shaping the woven fabric is inevitable. a city or a town is exposed to changes; therefore, the old parts of cities or towns should be adjusted to the life of a particular period. because of that reason city or town centres were being rebuilt, reconstructed or regenerated. a relevant present-day problem deals with the creation of new architecture in historical environment which makes an impact on the valuable properties of old towns. transformation as a process is inevitable when talking of a woven landscape fabric of a city or a town. a city is a “living organism”; something is being built, something is being demolished, some valuable properties are being revived, others are being destroyed. the valuable properties of a heritage object are closely interconnected with each other; having changed one the other will change too. a city is undergoing changes; therefore, old parts of cities or towns should be adjusted to the life of a particular period. because of that reason city or town centres were being rebuilt, reconstructed or regenerated. creation of new architecture in a historical environment as well as its harmony with the protected environment, lack of complex management work, construction of high-rising buildings and other issues ruining the valuable properties is a relevant present-day problem. the present article deals with the transformations of protected urban landscape throughout the time span. the reasons for the changes on these territories as well as essential factors making impact on the changes of these protected objects are estimated; also, their interrelation is explored and the ways to solve regulation of the change of urban landscape are presented. various old town definitions are found in the analysis of the scientific literature: integrated heritage unique and exceptional value (gurskienė v., ivavičiūtė g. 2012:45); the old parts of the city, which occur between the medieval city walls, or other clearly identified outside the historic core (vyšniūnas a. 2010:181); birthplace location and development program, which is implemented in an urban city community. old city leads essential identity and distinctiveness features that can be strengthened or weakened by various urban development ideas (rubavičius v. 2011:232). in this context, the historic core can be seen as a more specific place than old town or the oldest and introduction 51 journal of sustainable architecture and civil engineering 2017/1/18 most valuable part of it. the historic core the old part of town formed the entire territory of the city, fenced defensive wall or a special mode of construction area, with legally established limits, which is around the middle of the nineteenth century (jurkštas v. 1994. 9 psl.). the research object: protected urban landscapes – old towns, their valuable properties and management works. the aim of the research is to distinguish management and development principles of protected urban landscapes as old towns and their valuable properties. the analysis of valuable properties included all protected urban objects (100) listed in the register of culture values: old towns (7), historical centres (7), sites of ancient towns (38) and historical parts (48). percentages of valuable properties of these protected sites have been calculated: _ old towns: _ historical centres: _ sites of ancient town: _ historical parts: the calculations suggest that the most valuable are old towns (48%), including 7 of them in lithuania: vilnius, kaunas, klaipėda, kėdainiai, telšiai, ukmergė and trakai. as the old town of trakai is protected as an object territory and not as a locality, further on it will not be dealt with. research methods. the article presents the results of the research on transformations of protected urban landscapes that have been obtained applying the following research methods: _ analysis of archive data, examining information sources, books, scientific articles, legal acts regulating protection as well as register data; _ sociological survey of society members to find out the societal and specialists’ attitude towards the valuable properties of an old town; _ research of correlation analysis grounding the interrelation of valuable properties of old towns. analysis of the valuable properties of urbanistic structures characteristics of an urbanistic value can be named as valuable properties. the entire unity of an urbanistic structure is synthesis of its elements; its result is a historically formed cultural landscape. having carried out detailed analysis of the archive data, we can divide the valuable properties of old towns into three groups: landscape, urban and architectural. grounding on the data of the register of real estate culture heritage, the constituent elements of these properties are presented in fig. 1. already protected valuable properties should be supplemented with the valuable properties that have not been recorded in the register of culture heritage, that add to and ensure complexity of protection of a protected urban landscape. _ valuable properties of a landscape: area scale. _ urbanistic valuable properties: characteristics of construction, lines of construction along streets, infrastructure. _ architectural valuable properties: architectural solutions of façades, constructions, small architecture, architectural expression, styles, ways of harmonisation, traditional materials, colours, factures. journal of sustainable architecture and civil engineering 2017/1/18 52 correlation analysis of the valuable properties of an old town. calculation of coefficients of correlation analysis of old town valuable properties has been carried out employing ibm spss statistics program. first, the relevant data from the sociological survey of architecture specialists is uploaded to the spss program to carry out the correlation analysis. valuable properties of an old town having moderate and weak correlation relations are complex because they have more or less significant relations with other valuable properties. the results can be assessed in separate groups of landscape, urbanistic and architectural valuable properties. it was noticed that architectural valuable properties had only weak relations with landscape and urbanistic value properties. moreover, valuable properties of a landscape had weak interrelations only. after carrying out the correlation analysis, it was found that 21.88% of weak correlation relations, 3.9% of moderate correlations relations had been obtained; however, even 67.97% of correlation relations were insufficiently significant. valuable properties with moderate correlation relations and a 0.01 significance level can be singled out as more important valuable properties of an old town because after carrying out the same spearman coefficient correlation analysis involving more data, even 99% of obtained results would be identical. according to spearman correlation’s moderate relations of coefficients, their numbers, the relations of a 0.01 correlation significance level and old town valuable properties that are highly valuable to society and architecture specialists, we can point out the following essential valuable properties forming the fundamental of the value of an old town (fig. 2): fig. 1 landscape, urbanistic and architectural valuable properties (compiled by r. garbaliauskaitė) 1 open areas (landscape valuable property); 2 type and network of a planned structure (urbanistic valuable property); 3 quarters and possessions (urbanistic valuable property); 4 architectural expression, styles and ways of harmonisation (architectural valuable property); 5 small architecture (architectural valuable property). 53 journal of sustainable architecture and civil engineering 2017/1/18 the obtained valuable properties of old towns are attributed to all three (landscape, urbanistic and architectural) groups of valuable properties. we can draw a conclusion that the basis of the old town value consists of the interplay of all three groups and properly performed management works ensure protection, usage of an old town as a protected cityscape and the passing of it to the future generations. fig. 2 the most important valuable properties of an old town (compiled by r. garbaliauskaitė) on the ground of the results of the sociological survey of society and architecture specialists, urban valuable properties are indicated by the specialists as the most valuable among old town valuable property groups. they single out the volumetric spatial structure of an old town as the most worth protecting. the attitude towards new architecture inside old town differed between society and specialists: specialists advocate that new architecture inside old town should be based on the principle of contrast, and they support further development of old towns. whereas society members think that new architecture inside old town should resemble architecture of old buildings, and do not support further development of old towns. valuable properties depend on each other. their interrelation can be significant or insufficiently significant to influence the transformation. management works can be divided into two groups: protection and usage priorities. the essence of the protection priority management works lies in protection of authentic properties. the priority function is protection, the minor function is usage. the essence of the usage priority management works is usage because, primarily, by using protected objects we can ensure their protection. here, the priority function is usage, the minor function is protection. management works focused on protection and usage are presented in fig. 3. first of all, particular objects under analysis must have detailed historical, landscape, urbanistic and other research done; and only then they will be the ground for application of management works in different groups of valuable properties. one object may encompass valuable properties of all the groups and management works. each separate element must be individually decided on how it will be managed, what materials, means management works and possibilities for development journal of sustainable architecture and civil engineering 2017/1/18 54 will be used, what the ways of adjustment to the surrounding environment can be used (similar, neutral, contrasting). moreover, harmonisation among different valuable properties must prevail. fig. 3 application of management works in different groups of valuable properties (compiled by r. garbaliauskaitė) one of the key objectives of old town management is protection of valuable properties and identification of essential properties because these are the fundamental of the value of old towns. in the process of management of old towns, interdependence of valuable properties is highly important; they directly depend on each other, and when changing one, others may change too. this makes impact on the transformation of an old town. development works mean the mending of streets, squares, improvement of engineering infrastructure, the issues of transportation and parking lots, projection of new construction. all this must be coordinated with protection of the authenticity and particularity of the urbanistic value (glemža, j. r. 2002:150-151). currently, the problem of cities is enclosed in their development proceeding in the direction of suburbs; however, when drawing strategic development plans, it is important to note densification of a city (pakalnis m. 2000) within existing limits. usually, old parts and old towns of cities are attributed with the lowest density of residents in a city. this is influenced by low buildings with residential upper floors and lower floors allocated for 55 journal of sustainable architecture and civil engineering 2017/1/18 commerce. special plans are being drawn to legally regulate activities in protected cityscapes. urban development through particular physical elements can emphasise or level specificity of visual expression of landscape, including the unity, uniqueness of the landscape character (laukaitytė-malžinskienė, g. i. 2008:110). therefore, it is highly important to facilitate full harmonisation among the landscape and valuable properties, protected, non-protected and newly designed buildings. conclusions _ having carried out the search for protected objects included in the register of culture values, examples of old towns in lithuania have been explored, their already protected valuable properties have been singled out and other additional properties have been suggested to be included into the register of culture values for the purpose of protection: area scale, characteristics of construction, lines of construction along streets etc. _ after carrying out research, it was found out that the most valuable properties were dependent on each other. their interrelation can be significant or insufficiently significant to make impact on the transformation. valuable properties of an old town having moderate and weak relations are complex because they have more or less significant relations with other valuable properties. the valuable properties having moderate strength correlation relations (from 0.5 to 0.7) and a 0.01 significance level can be more important valuable properties of an old town because after carrying out an identical spearman coefficient correlation analysis including more data, even 99% of obtained results would be the same. _ having analysed the data of sociological surveys and correlation analysis, the most important valuable properties of old towns have been singled out: open spaces; type and network of a planned structure; quarters, possessions; architectural expression, styles, ways of harmonisation; small architecture. _ the fundamental of the old town value consists of the interplay of all three (landscape, urbanistic and architectural) groups of valuable properties and properly carried out management works ensure protection, usage of an old town as a protected cityscape and the passing of it to the future generations. gurskienė v., ivavičiūtė g. 2012. kraštovaizdžio planavimas. kauno r.: akademija. 169 p. isbn 978-609449-0316. access via the internet (accessed on 25-09-2015): http://dspace.lzuu.lt/bitstream/1/1985/1/krastovaizdzio_planavimas.pdf vyšniūnas a. 2010. šiaulių miesto centrinė dalis ar urbanistikos paveldo saugotinos teritorijos. town planning and architecture. 181-194 p. issn: 13921630. access via the internet (accessed on 29-102015): http://www-tandfonline-com.ezproxy.ktu. edu/doi/pdf/10.3846/tpa.2010.18 . rubavičius v. 2011. vilniaus senamiestis – gyvosios kultūrinės atminties šerdis. town planning and architecture. 231-237 p. issn: 1392-1630. access via the internet (accessed on 29-10-2015): http:// www-tandfonlinecom.ezproxy.ktu.edu/doi/ pdf/10.3846/tpa.2011.24. referencesjurkštas v. 1994. senamiesčių regeneracija: architektūros harmonizavimo problema. vilnius: technika. 138 p. isbn 9986-05-139-8. glemža j. r. 2002. nekilnojamojo kultūros paveldo apsauga ir tvarkymas. vilnius: vilniaus dailės akademijos leidykla. 150-151 p. isbn 9986-571-84-7. laukaitytė-malžinskienė g. i. 2008. kraštovaizdžio vizualinės raiškos savitumo apsauga didmiesčio priemiestinėse teritorijose. town planning and architecture. 110 p. issn: 1392-1630. access via the internet (accessed on 18-11-2015): http:// w w w t a n d f o n l i n e c o m . e z p ro x y . k t u . e d u / d o i / pdf/10.3846/13921630.2008.32.103-112 pakalnis m. 2000. miestų užstatymo tankinimo metodikos parinkimas ir vilniaus naujamiesčio tankinimo programa. urbanistika ir architektūra, vol. xxiv, no. 4. 149-162 p. issn: 1392-1630. journal of sustainable architecture and civil engineering 2017/1/18 56 rūta garbaliauskaitė master student kaunas university of technology, faculty of civil engineering and architecture, departament of architecture and urbanism main research area protected urban landscapes address studentu 48, lt-51367 kaunas, lithuania tel. +37064496835 e-mail: rutagarbaliauskaite@gmail.com aušra mlinkauskienė assoc. professor kaunas university of technology, faculty of civil engineering and architecture, departament of architecture and urbanism main research area protection of immovable cultural heritage objects; research of values of cultural landscapes and urban structures; evaluation of protected areas address studentu 48, lt-51367 kaunas, lithuania tel. +370 684 79181 e-mail: ausra.mlinkauskiene@ktu.lt about the authors 13 journal of sustainable architecture and civil engineering 2016/2/15 corresponding author: ingrida.povilaitiene@ktu.lt residents’ sense of the place in galata neighbourhood, in istanbul received 2016/06/06 accepted after revision 2016/08/16 journal of sustainable architecture and civil engineering vol. 2 / no. 15 / 2016 pp. 13-19 doi 10.5755/j01.sace.15.2.15121 © kaunas university of technology residents’ sense of the place in galata neighbourhood, in istanbul jsace 2/15 http://dx.doi.org/10.5755/j01.sace.15.2.15121 introduction ingrida povilaitienė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania the paper intends to examine the sense of the place phenomenon, which can be defined as a result of constant interaction between psychophysiological mechanisms of human-beings and physical properties of tangible environment. shamai’s (1991) approach to sense of the place will be employed in this research. according to his suggested scale, level of sense of the place varies from “not having any sense of a place” to “sacrifice for a place” (shamai, 1991). the generic hypothesis of this research is that there are certain factors (historical, social, cultural, physical or temporal) which determine particular level of sense of the place. the case study of galata neighbourhood will be carried out in order to gain better understanding of sense of the place phenomenon and to define the significance of its decisive factors. galata is a very special historical neighbourhood of istanbul. it was established as a western, latin and catholic colony. later on, it became a residential area for greeks and jews. thus, this area was a non-muslim area for quite a long time. turkish people started to move in here more abundantly only since the middle of the twentieth century. despite that, galata neighbourhood has kept its international character even till now. today galata is famous worldwide for the richness of architectural, cultural and religious heritage and it attracts millions of tourist every year. therefore, it is even more interesting to understand how locals feel this place and what factors strengthen their place attachment. keywords: galata neighbourhood, istanbul, place attachment, sense of place. the world around is not fixed. everything changes and cities are not an exception. urban spaces are transformed over and over again. it is never-ending process. still, despite that permanent change,”<…> inhabited place has to inform us not only were we are geographically, but it has to inform us, where we are in our culture“ (kunstler, 2004). there should be a spirit of the place. actually, majority of inhabited places evoke certain feelings. however, the question is what kind of feelings and why? definitely, there plenty of research trying to answer this question. still, when people’s feelings are involved the unique situations might appear and unique situations call for the unique studies. therefore, the aim of this paper is to examine residents’ sense of the place phenomenon in galata neighbourhood. it will be a transactionally oriented research because the phenomenon will be treated as holistic unit rather than combination of separate elements. scientific literature distinguishes four qualities of socio-behavioural phenomena, which are as follows: physical environment, people, psychological processes and time with its temporal qualities (werner et al, journal of sustainable architecture and civil engineering 2016/2/15 14 2003). in this research, public spaces of galata neighbourhood are chosen as a physical environment. the study will be targeted to the certain group of people – social participants, which are residents of the neighbourhood. the psychological process which will be tackled is sense of the place at the present time (see fig. 1). actually, the reason why focus is particularly fig. 1 the aim of the research – analysis of socio-behaviour phenomenon on the residents of the district is the nature of sense of place phenomenon. it is a very complex psychological process, encompassing the meanings and the attachments that people develop for the certain place. thus, the level of the sense of the place might depend on the familiarity with the place and time spent here. however, it is still hypothetical statement, which will be tested further. the methods of the research include: overview of the scientific literature, related with historical development of galata neighbourhood; descriptive analysis of existing situation in galata; comparative analysis of scientific methods which could be applicable to evaluate sense of the place; the semi-structured interview with the residents; systematization, comparison and generalization of all collected data. galata name comes from old times and it is not an official administrational unit of istanbul at the present (galata belongs to the borough of beyoğlu). though, this term is still commonly used to define the area, located at the north side of the golden horn, towards taksim square. it might be that history of galata area goes back to 1200 b.c., when greek clans probably built up the first settlement here. anyway, there are not any doubts, that galata was inhabited area later on. during the roman imperial period, the settlement was thrifty and around the fourth century a.d. galata city was surrounded by walls for the first time. this area also was prosperous during the byzantium period: walls of the city were enlarged, galata citadel was built and the significance of galata as privileged commerce centre was still growing. the tranquillity was disturbed for a while by crusader occupation. though, after latin people were conquered by byzantines, the whole galata district was left for genoeses and genova colony was established. during the ottoman empire, whole istanbul and especially galata area was cosmopolitan. a lot of embassies were opened here. as ottomans were interested in western culture, the foreign institutions, restaurants and cafes were flourishing. after founding the republic of turkey, ankara became its capital and the foreign embassies moved there. thus, galata became emptier, but still kept its position as the most important business centre in istanbul, because of a very good strategical location. also, galata district went through the modernization process with drastic demolishment and radical changes of urban pattern during the first decades of the republic. later on, the local population also did not escape the changes. local inhabitants of other nationalities moved to their home countries or somewhere else, due to the establishment of “property tax”, following that more turkish people moved into the galata district. intensive urban transformations of galata area lasted till 1993, when it was defined as urban protected area. since 2000, the cultural life has increased significantly here. galata neighbourhood became a very attractive place for artists and designers. (yarıkkaya, 2003; özgür et al, 2013; özlü et al, 2013). historical development of galata neighbour hood 15 journal of sustainable architecture and civil engineering 2016/2/15 sense of the place analysis of any psychological process is a difficult challenge. a deep understanding of the process itself is necessary to start with and then the methodology of process assessment is equally important. there is a plethora of concepts describing relationship between people and spatial settings (e.g., place identity, place dependence, place attachment and etc.). however, sense of the place is chosen as the most general umbrella term that covers other notions, because this concept reflects not only positive people’s relation with the place (as place attachment, for example) but any kind of emotions (table 1). table 1 concept if sense of the place d im e n s io n s / a tt r ib u te s sense of the space analysis of people’s feelings toward place negative feelings neutral phase positive feelings 1. belonging to place 2. place attachment: 2.1. place identity; 2.2. place dependence. 3. place commitment according to analysed literature, several levels of sense of the place can be distinguished and defined as dimensions or attributes: negative feelings – the most of overviewed studies ignore this dimension. however, certainly, some places can evoke negative emotions and sometimes they cannot be ignored (shamai et al, 2005). neutral phase is when the place does not cause any feelings. some authors define this phase as “not having any sense of the place” (shamai, 1991; shamai et al, 2005), others as “homelessness” or “not belonging to place” (relph, 1976). positive feelings – the content and hierarchical structure of this dimension vary among the theories. different authors suggest different methodological systems. therefore, sometimes the same attribute might not have the same meaning in different methodological models. for example, relph (1976) described positive feelings toward place as “belonging to place” or “deep identity with the place”; proshansky (1978) used a term of “place identity” to define the emotional attachment to the place; while stokols and shumaker (1981) defined functional attachment to the place as “place dependence”. later on, several academicians (william et al, 1989; altman et al, 1992; williams et al, 1995; vaske et al, 2001; williams et al, 2003 and etc.) used “place attachment” as more general term that covers both “place identity” and “place dependence”. however, the use of this term also might be confusing, because we can find the attribute of “attachment” as one of five components of lalli’s (1992) urban identity scale. it is unclear if the “place attachment” is a component of “place identity” or vice versa. therefore, shamai’s (1991) model of “sense of the place”, which integrates all attributes into one hierarchical system, is chosen to define the attributes of positive feelings in this research: 1 belonging to place – the lowest level of positive feelings toward place. there is not strong or intense affection still. however, according shamai (1991), there is knowledge of being located in place and the feeling of belonging. 2 place attachment – is higher level of positive feelings, because emotions intensify and the place starts to influence people’s behaviour in certain ways. people feel attached to place and identify themselves with place goals (shamai, 1991). this dimension consists of: 2.1. place identity – emotional attachment (proshansky, 1978) 2.2. place dependence – functional attachment (stokols et al, 1981) 3 place commitment – the highest level of positive feelings toward a place. full involvement to a place and even sacrifice for a place (shamai, 1991). based on this hierarchical system, the semi-structured interview was designed to reveal residents’ sense of the place in galata neighbourhood. journal of sustainable architecture and civil engineering 2016/2/15 16 results of the interviews thirty respondents were interviewed for this research. ninety percent of them were younger than 40 years old. such young age of the sample was influenced by the language barrier, as the questions were prepared and interviews were carried out in english. thirty percent of interviewed people were born in istanbul. in general, an average duration of residence in istanbul was sixteen years and respondents have lived averagely for three years in galata neighbourhood. based on “sense of the place” scale (shamai, 1991), respondents were asked to evaluate their feelings toward place in three different spatial scales: considering whole istanbul city, beyoğlu administrative district and galata neighbourhood (see fig. 2). results revealed, that the place got the highest rates at smallest scale and the sense of the place and place attachment were gradually decreasing for the bigger geographical units. most of the respondents said that they feel belonging to istanbul (40%) or they are emotionally attached to it (30%). meanwhile, respondents not only feel emotionally attached to galata neighbourhood (30%), but also identify with the lifestyle and values of the other people who live here (30%) and even they would make personal sacrifices to save, protect or maintain galata neighbourhood as it is (30%). it was also noticed, that there is a moderate positive correlation between duration time of residence in galata neighbourhood and its rating (r=0,51). that means, the longer people live in the neighbourhood, the more attached they feel. there was no such correlation regarding whole istanbul city (r=0,23). therefore, it can be claimed, that people maintain stronger sense of place for their neighbourhood as they experience its spaces every single day, while the sense of the whole city is more distant and fragmented concept. during the interviews, respondents were also asked about the factors influencing their sense of attachment in galata neighbourhood. four possible aspects were distinguished by author: social network and friendships (1), culture and lifestyle (2), geographical location (3) and physical environment (4). respondents also had a possibility to suggest something else. likert scale (from 1 to 5, where 5 indicates the most important and 1 – the least important factor) was used to evaluate the significance of these factors. culture and lifestyle was chosen as the most salient aspect of galata neighbourhood. the importance of social network and friendships was also rated quite fig. 2 different scale geographical units 17 journal of sustainable architecture and civil engineering 2016/2/15 fig. 3 average ranking values of place’s aspects high. geographical location got a little less points and was left in the third place. finally, physical environment was considered as the least important aspect (fig. 3). furthermore, the results of rating showed, that there is a significant positive correlation between the duration of residence time in galata and the importance of social network and friendships (r=0,82). besides, there is a significant negative relationship between the time of residence and the level of importance of geographical location (r=-0,84) and a moderate negative correlation between the residence time and the rating of cultural and lifestyle aspect of galata district (fig. 4). all these correlations revealed, that people, who settled down recently in the area, appreciate it because of the convenient, central and strategic location or because of the unique cultural atmosphere and bohemian lifestyle. however, the longer they live here, the less important these primary factors become. during the time, people make friends, start to form and expand social networks and later they try to maintain and foster them. thus, even though the culture and lifestyle got the highest rate in this research, the aspect of social network and friendships might be fig. 4 distribution of ranking values of different aspects of the galata neighbourhood depending on residence time journal of sustainable architecture and civil engineering 2016/2/15 18 even more important, as only this aspect shows the growing tendency during the time. by the way, level of physical environment’s influence on the respondents’ place attachment did not have any relation with their residence time. the question about associations with “galata district” revealed that the most iconic symbol is galata tower as ninety present of respondents mentioned it (fig. 5). although some of the interviewed people mentioned several disadvantages of the galata neighbourhood (such as too overcrowded, too touristic or too hilly place), none of respondents said that they would wish to live somewhere else because of these negative factors. conclusions fig. 5 galata tower is a symbol of whole neighbourhood (photo by i. povilaitienė) definitely, there are few limitations of this research. first, that the sample of respondents is pretty small for the interviews, thus it is quite difficult to get the comprehensive understanding about the phenomenon. second, that only english-speaking respondents were involved into the interviewing process and the significant insights might be missing because there is no data collected about feelings toward place from older generation. third, that the results also might be influenced by “trendy ideas”, because when people are asked to answer the questions, they purposively think about it and their answers might be biased. therefore, another methods of data collection (like pure observation) might be very useful in providing the unprejudiced evidence about the phenomenon. overall, this research reveals, that time of residence is a very crucial aspect for the sense of the place. people, who live longer in the place, feel much more attached to it. furthermore, the significance of all other factors (social, cultural, strategical) influencing the positive sense of the place, changes over the time. only the properties of physical environment are independent from residence of time. however, surprisingly physical properties also were not found as a decisive factor for the sense of place in this research. it might be, that the intensity and abundance of other factors overshadow the static characteristics. another explanation could be that, there is a good environmental fit, as “…we are unaware of being comfortable. we are more aware when we feel uncomfortable…” (lang, 1987). the author wishes to thank prof. dr. j. kamičaitytė-virbašienė for always helpful discussions and valuable comments. also the author is sincerely thankful for prof. dr. a. ünlü and dr. m. e. şalgamcıoğlu for their useful advice and help in the study design. acknowledgment references altman i., low s. m. place attachment. human behavior and environment, 1992; 12: 1-12. http://dx.doi.org/10.1007/978-1-4684-8753-4 kunstler h. j. the ghastly tragedy of the suburbs. 2004 (accessed 16 november, 2015). available at: https://www.ted.com/talks/james_howard_kunstler_dissects_suburbia?language=en lalli m. urban-related identity: theory, measurement and empirical findings. journal of environmental psychology, 1992; 12(4): 285-303. http://dx.doi.org/10.1016/s0272-4944(05)80078-7 lang j. creating architectural theory: the role of the behavioral sciences in environmental design. new york: van nostrand reinhold; 1987. 19 journal of sustainable architecture and civil engineering 2016/2/15 özgür s., olgun i. (eds.) by_pass_ing karaköy. istanbul: mimar sinan güzel sanatlar üniversitesi yayınları; 2013. özlü, n., gratien ch. producing pera: a levantine family and the remaking of istanbul. ottoman history podcast, 2013, no. 90 (accessed 15 december, 2015). available at: http://www.ottomanhistorypodcast.com/search/label/alexander%20vallaury proshansky h. m. the self and the city. environment and behavior, 1978; 10(2): 147-169. http://dx.doi.org/10.1177/0013916578102002 relph e. place and placelessness. london: pion; 1976. shamai s. sense of place: an empirical measurement. geoforum, 1991; 22(3): 347-358. http://dx.doi.org/10.1016/0016-7185(91)90017-k shamai s., ilatov z. measuring sense of place: methodological aspects. tijdschrift voor economische en sociale geografie, 2005; 96(5): 467-476. http://dx.doi.org/10.1111/j.1467-9663.2005.00479.x stokols d., shumaker s. a. people in places: transactional view of settings. cognition, social behavior, and the environment, 1981; 441-488. vaske j. j., kobrin k. c. place attachment and environmentally responsible behavior. the journal of environmental education, 2001; 32(4): 16-21. http://dx.doi.org/10.1080/00958960109598658 werner c. m., brown b. b., altman i. transactionally oriented research: examples and strategies. handbook of environmental psychology. new york: john wiley & sons; 2003: 203-221. williams d. r., anderson s. b., mcdonald c. d., patterson m. e. measuring place attachment: more preliminary results. san antonio, texas; 1995. williams d. r., roggenbuck j. w. measuring place attachment: some preliminary results. san antonio, texas; 1989. williams d. r., vaske j. j. the measurement of place attachment: validity and generalizability of a psychometric approach. forest science, 2003; 49(6): 830-840. yarıkkaya g. forging new spaces for a new identity: review of 19 yüzyilin ikinci yarisinda galata ve pera. [the second half of the 19th century in galata and pera]. journal of historical studies, 2003; 1: 51-55. ingrida povilaitienė phd student kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research area cultural and urban identity, the relation between human-beings and their environment address v. krėvės pr. 28-12, 50411 kaunas, lithuania tel. +370 609 50483 e-mail: ingrida.povilaitiene@ktu.lt about the author journal of sustainable architecture and civil engineering 2016/1/14 12 *corresponding author: danute.palubinskaite@ktu.lt the utilization of biomass bottom ashes in cement system received 2016/04/10 accepted after revision 2016/05/30 journal of sustainable architecture and civil engineering vol. 1 / no. 14 / 2016 pp. 12-19 doi 10.5755/j01.sace.14.1.14893 © kaunas university of technology the utilization of biomass bottom ashes in cement system jsace 1/14 http://dx.doi.org/10.5755/j01.sace.14.1.14893 introduction danutė vaičiukynienė*, vitoldas vaitkevičius, jūratė krulikauskaitė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania aras kantautas kaunas university of technology, faculty of сhemical technology radvilenu st. 19, lt-50254 kaunas, lithuania vilimantas vaičiukynas aleksandras stulginskis university, faculty of water and land management universiteto g.10, lt53361 akademija, kaunas district municipality, lithuania valdas rudelis joint-stock company “lifosa”, juodkiškio st. 50, lt-57502 kėdainiai, lithuania by producing 1 ton of portland cement clinker in environment releasing about 0.85 tons of co2: 70% of limestone decarbonation and 30% of electricity and thermal consumption. high specific co2 emissions results take the responsibility of portland cement industry for about 5% of global co2 emissions. one of the ways to reduce co2 emissions is the use of portland cement substituting materials. properly treated ashes could become not a waste of biofuel but a valuable raw material for new construction materials. this paper presents results about the characterization of the biomass bottom ash sourced from the combustion of plant biomass located in lithuania, and the study of new cement formulations incorporated with the biomass bottom ash. the study includes a comparative analysis of the phase formation and the setting of cement with bottom ash composite. techniques such as x-ray diffraction (xrd), x-ray fluorescence spectroscopy (xrf), measurement of hydration temperature were used to determine the structure and composition of the formulations. keywords: biomass bottom ash, hardened cement paste, zeolite. biomass is a renewable energy source that is increasingly being used worldwide. however, because of recent increases in production, waste products from biomass combustion are becoming a relevant environmental and economic problem. currently biomass bottom ash from biomass combustion is waste with no practical applications and generally deposited in landfills. because of the pozzolanic contribution of conventional concrete, biomass bottom ash can also be used as a partial substitute for cement. biomass fly/bottom ashes have been used to produce mortars in addition to commercial cement. the presence of ash modifies the pastes rheological behavior. materials display fair compression strength after 28 d of ageing in water. materials aged 180 d in water suffer of high potassium elution (maschio et. al., 2011). in the research (da luz 13 journal of sustainable architecture and civil engineering 2016/1/14 garcia et al., 2013) suggest bottom-ash, a waste material to ground and to test for use as a partial cement replacement material. mortar with ground bottom-ash showed marginal durability loss but improved strength at later ages. ground bottom-ash, non-glassy, may be used as a filler, contributing to sustainable construction. there are some results have been published on the use of biomass bottom ash as filler in concretes or in road embankments. the results prove the feasible application of biomass bottom ashes as filler in road embankments. furthermore, its use as cement-treated materials or non-structural concrete, depending on the replacement percentage (hinojosa et. al., 2014). in the research (beltrán et. al., 2014), concrete consisting of recycled aggregate substitutions was manufactured by applying different replacement rates of natural sand with biomass bottom ash. the results showed a worse behavior in mechanical properties and durability properties, however these reductions were inferior to it can be expected, due to the appropriate manufacture of the concrete applied. in another work (cabrera et. al., 2014) it was determined that biomass bottom ash possesses acceptable properties to be used as a filler material in the core of road embankments over 5 m in height without additional precautionary measures, such as the construction of road shoulders. in the research (beltrán et al., 2014) three series with different amount of biomass bottom ashes manufacture. mechanical properties were negatively with the addition of recycled aggregates. durability properties declined with increasing recycled aggregates. in another work (modolo et al., 2013) determined that bottom ash from biomass burning can be used as aggregate in mortars. incorporation does not induce negative impacts. mortar producers due to the replacement of treated and calibrated sand may achieve economic savings. in the research (beltrán et al., 2016) analyzed samples of biomass bottom ashes from wood and olive trees. low density, high absorption and high organic matter content were observed. biomass bottom ashes were classified as subsidiary material feasible as construction material. the use of the ashes as a filler material in road embankments was proved. some scientists suggest biomass bottom ashes to utilize as component in building materials. for ashes that cannot be recycled it is possible to utilize as building material or as component in building products. the key factors for success in all forms of utilization are consistency of ash quality and availability of large quantities (pels et al., 2005). in the present work (wang et al., 2007) the use of biomass bottom ash significantly increased the porosity of mortars and it led to the decline of mechanical properties. according to the carrasco et al., (2014) the addition of bottom ash increases the material’s porosity, thereby decreases its thermal conductivity and compressive strength. the mixture with a 1:1 si/ca molar ratio shows the best mechanical characteristics (61.11 mpa) with acceptable thermal conductivity value (0.773 w/mk) and could potentially be used in products such as building blocks, since partially replacing the cement with ash produced samples based on criteria of the en standards. the aim of this work is to investigate possibilities of hydrothermal treated biomass bottom ashes in portland cement mixtures. xrd analysis data show that in the biomass bottom ashes (fig. 1) silicon dioxide and calcium carbonate prevailed. there are small amount of calcium oxide, magnesium oxide, anorthoclase and gehlenite. in investigated biomass bottom ashes it is believed that calcium oxide should be left after firing of biomass. it is slowly hydrate and going carbonation. amorphous sio2 waste are industrial by-product, i. e., amorphous sio2 · nh2o (lifosa, lithuania). this amorphous sio2 is polluted with the impurities of fluoride compounds. chemical composition of this waste is show in tabale 1. the commercial portland cement of type cem i 52.5r was used for the tests. chemical composition of portland cement and biomass bottom ashes was given in table 1. after the xrf analysis it was determined that cao (48.97 %), sio2 (22.39 %), mgo (8.29 %), and k2o (8.69 %), contain the largest amount of oxides in the biomass bottom ashes (table 1). materials and methods journal of sustainable architecture and civil engineering 2016/1/14 14 reagents naoh (delta chem, czech republic), al(oh)3 (lachema, czech republic) was used in this work as well. the x-ray diffraction analysis of the materials was performed using the x-ray diffractometer bruker d8 advance. cukα radiation and ni filter were used. the power x-ray diffraction patterns were identified with references available in pdf-2 data base (pdf – 2 international centre for diffraction data, 12 campus boulevard newtown square, pa 19073-3273 usa). chemical compositions of these materials were investigated by x-ray fluorescence spectrometer bruker x-ray s8 tiger wd, using rhodium (rh) tube, anode voltage ua up to 60 kv, electric current i up to 130 ma. the pressed samples were measured in helium atmosphere. measurements were performed using spectra plus quant express method. the cement paste hydration temperature measurements were performed with 8-channel usb tc-08 thermocouple data logger (temperature measurement range from -270 to +1820 °c). the suspension of biomass bottom ash was treated in hydrothermal way. zeolitization conducted in the kiln snol 200/200 for 1 hour at 100oc. notes: q – silicon dioxide sio2, ca – calcium oxide cao, m – magnesium oxide cc – calcium carbonate caco3, a – anorthoclase (na,k)(si3al)o8, g – gehlenite ca2 al(alsio7). chemical composition, % portland cement clinker biomass bottom ashes amorphous sio2 waste sio2 20.61 22.39 71.64 al2o3 5.45 2.51 11.26 fe2o3 3.36 2.18 1.31 cao 63.42 48.97 0.42 so3 0.80 0.58 mgo 3.84 8.29 k2o 1.31 8.69 na2o 0.94 0.28 p2o5 5.05 mno 0.35 tio2 0.33 bao 0.16 sro 0.06 rb2o 0.02 zro2 0.04 zno 0.04 cuo 0.02 cl 0.04 f 20.84 fig. 1 x-ray diffraction pattern of biomass bottom ashes table 1 chemical composition of portland cement clinker and biomass bottom ashes and amorphous sio2 waste 15 journal of sustainable architecture and civil engineering 2016/1/14 by replacing 10 % of portland cement to biomass bottom ashes 4×4×16 cm samples from this cement paste were made. it was found that micro and macro cracks opened while these samples were harden (fig 1.). the reason of these defects should be calcium and magnesium oxides hydration reaction (1 and 2). it causes volume expansion, internal stresses and cracks appearance in the solid sample. therefore, in cement systems biomass bottom ashes cannot be used without additional processing. there are many researches (liu, 2016; nagrockiene et al., 2016; gerengi et al., 2015; małolepszy et al., 2015), where zeolite as portland cement substituting materials are widely used. therefore, in this study the biomass bottom ashes were an attempt to zeolitize. the zeolitization of biomass bottom ashes may be obtained by heating some aluminosilicate materials in the presence of alkaline solutions. the process of zeolitization took place according this scheme: biomass bottom ashes (cao, mgo) + amorphous sio2 waste al(oh)3 + h2o + naoh h hydrothermal treatment t ≈ 100 °c, 1 h h biomass bottom ashes + zeolite + calcium silicate hydrate it was prepared five samples series (table 2). in the mixtures no 1 and no 2 only biomass bottom ashes without amorphous sio2 waste addition was used. in the last three (no 3, no 4 and no 5) mixtures two-aluminosilicate materials was used. (1)cao +h2o → ca(oh)2 (2)mgo +h2o → mg(oh)2 no sio2, mol al2o3, mol na2o, mol h2o, mol the source of sio2 and al2o3 biomass bottom ashes, % amorphous sio2 waste, % 1 2 1 2 15 100 2 2 1 1 15 100 3 2 1 2 15 50 50 4 2 1 2 15 70 30 5 2 1 2 15 80 20 after zeolization of investigated mixture the mineral composition of it was found (fig. 2). based on the xrd investigation in mixtures products silicon dioxide, aluminum hydroxide, calcium aluminum iron silicate hydroxide, calcium carbonate predominates and harmful, not hydrated calcium and magnesium oxides there are. thus, by using hydrothermal treatment of investigated mixture no1 and no2 the harmful calcium and magnesium oxides was not bonded to compounds. results and discussion fig.1 hardened cement paste sample with biomass bottom ashes (one half of sample 4×4×16cm) table 2 the quantities of primary materials for zeolitization journal of sustainable architecture and civil engineering 2016/1/14 16 therefore, part of ash was mixed with amorphous sio2 waste in order to intensify the reaction of harmful calcium and magnesium oxides (table 2, mixture 3-5). after the examination of zeolitized mixtures, it was found that in all three mixtures zeolite and calcium silicate hydrates were formed. it is important to emphasize that in this case, harmful calcium and magnesium oxides were fully bind into compounds that are harmless to cement hydration. it is likely that using zeolitized products of no 3 no 5 mixtures as a portland cement replacement material, it should not be caused problems for cement systems during hydration. notes: q – silicon dioxide sio2, al – aluminum hydroxide al(oh)3, cc – calcium carbonate caco3, ca – calcium oxide cao, cf – calcium aluminum iron silicate hydroxide ca3alfe(sio4)(oh)8, a – anorthoclase (na,k)(si3al)o8 notes: q – silicon dioxide sio2, cc – calcium carbonate caco3, na – zeolite na2oal2o31.68sio2·1.8h2o, cf – calcium aluminum iron silicate hydroxide ca3alfe(sio4)(oh)8, g – gehlenite ca2al(alsio7), k – calcium silicate hydrate ca1.5sio3.5·xh2o fig. 2 x-ray diffraction pattern of zeolitized biomass bottom ashes fig. 3 x-ray diffraction pattern of zeolitized biomass bottom ashes 17 journal of sustainable architecture and civil engineering 2016/1/14 after the x-ray diffraction the hydration temperature of cement paste tests was measured (fig. 4). it was determined that the main peaks of all investigated portland cement pastes are higher in the specimens with 5% of zeolitized materials (mixtures 3 – 5). in all investigated cases, portland cement paste hydration temperature increased compared with the reference specimen temperature. these temperature increases can be explained by filler effect. the physical presence of particles enhanced the hydration of the clinker phases. this effect is called the filler effect. this effect has been attributed to the increase of the number of nucleation sites provided by the extra surface from the particles (berodier et al., 2012). investigating specimens with no 4 and no 5 zeolitzed material, hydration temperatures were very similar to the control specimen. by using zeolitzed material no 3, the main reaction of hydration, it was with longer duration than control specimen (from 630 min until 702 min). this indicates that zeolitzed material no 3 slightly delays the hydration of hardened cement paste. _ it was found that the biomass bottom ashes cannot be used directly as portland cement substituting material due to calcium and magnesium oxides hydration reactions in already hardened samples. in these samples volume increases and cracks occur during hardening process. _ it has been found that in the zeolitization products of biomass bottom ashes with amorphous sio2 waste mixtures calcium and magnesium oxides are bind in complex compounds of zeolite and calcium silicates hydrates. for this reason, do not cause problems during portland cement hydration. _ in all investigated cases, portland cement paste hydration temperature increased compared with the reference specimen temperature. these temperature increases can be explained by filler effect. notes: 3, 4, 5 according table 2. fig. 4 the dependence of hydration temperature of portland cement paste on the amount of biomass bottom ash conclusions journal of sustainable architecture and civil engineering 2016/1/14 18 beltrán, m.g., agrela, f., barbudo, a., ayuso, j., ramírez, a. mechanical and durability properties of concretes manufactured with biomass bottom ash and recycled coarse aggregates, construction and building materials, 2014; 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(. potential use of biomass bottom ash as alternative construction material: conflictive chemical parameters according to technical regulations. fuel, 2014; 128: 248-259. liu, q.w. influences of concrete mechanical properties when using zeolite powder as admixture. in material science and engineering: proceedings of the 3rd annual 2015 international conference on material science and engineering (icmse2015, guangzhou, guangdong, china, 15-17 may 2015). crc press; 2016, march. maschio, s., tonello, g., piani, l., furlani, e. fly and bottom ashes from biomass combustion as cement replacing components in mortars production: rheological behaviour of the pastes and materials compression strength. chemosphere, 2011; 85(4): 666-671. modolo, r.c.e., ferreira, v.m., tarelho, l.a., labrincha, j.a., senff, l., silva, l. mortar formulations with bottom ash from biomass combustion. construction and building materials, 2013; 45: 275-281. małolepszy, j., grabowska, e. sulphate attack resistance of cement with zeolite additive. procedia engineering, 2015; 108: 170-176. nagrockiene, d., girskas, g. research into the properties of concrete modified with natural zeolite addition. construction and building materials, 2016; 113: 964-969. pels, j.r., de nie, d.s., kiel, j.h. utilization of ashes from biomass combustion and gasification. in 14th european biomass conference & exhibition; 2005, october wang, s., baxter, l. comprehensive study of biomass fly ash in concrete: strength, microscopy, kinetics and durability. fuel processing technology, 2007; 88(11): 1165-1170. references 19 journal of sustainable architecture and civil engineering 2016/1/14 danute vaičiukunienė professor kaunas university of technology, faculty of civil engineering and architecture main research area building materials address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300465 e-mail: danute.palubinskaite@ ktu.lt vitoldas vaitkevičius professor kaunas university of technology, faculty of civil engineering and architecture main research area building materials address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300465 e-mail: vitoldas.vaitkevicius@ ktu.lt aras kantautas assoc. professor kaunas university of technology, faculty of chemical technology main research area building materials address radvilenu st. 19, lt-50254 kaunas, lithuania tel. +370-37-300163 e-mail: aras.kantautas@ktu.lt vilimantas vaičiukynas lector aleksandras stulginskis university, faculty of water and land management main research area drainage construction materials address universiteto g.10, lt53361 akademija, kaunas district municipality, lithuania tel. +370 61434230 e-mail: vilimantas.vaiciukynas@ outlook.com jūratė krulikauskaitė master student kaunas university of technology, faculty of civil engineering and architecture main research area building materials address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300465 e-mail: j.krulikauskaite@gmail. com valdas rudelis engineer technologist joint-stock company “lifosa” main research area building materials address juodkiškio st. 50, lt-57502 kėdainiai, lithuania tel. +370 61282463 e-mail: v.rudelis@lifosa.com about the authors 75 journal of sustainable architecture and civil engineering 2017/4/21 *corresponding author: chenjiajian@fosu.edu.cn use of quartz sand to produce low embodied energy and carbon footprint plaster received 2017/11/23 accepted after revision 2017/12/28 journal of sustainable architecture and civil engineering vol. 4 / no. 21 / 2017 pp. 75-81 doi 10.5755/j01.sace.21.4.20005 © kaunas university of technology use of quartz sand to produce low embodied energy and carbon footprint plaster jsace 4/21 http://dx.doi.org/10.5755/j01.sace.21.4.20005 jiajian chen* department of civil engineering, foshan university, 528000 foshan, china pui-lam ng faculty of civil engineering, vilnius gediminas technical university sauletekio ave. 11, lt-10223 vilnius, lithuania roman jaskulski, wojciech kubissa faculty of civil engineering, mechanics and petrochemistry, warsaw university of technology 17 łukasiewicza st., 09-400 płock, poland introduction plaster is a widely adopted material in buildings. however, since the manufacturing of cement, a common component material in plaster, involves heating limestone and emits a lot of carbon dioxide, there is inherent problem pertaining to plaster that it is associated with a large amount of embodied energy and carbon footprint. one strategy to solve the problem is to employ quartz sand, an economic and abundant natural resource, to partially replace cement for plaster production to directly reduce the embodied energy and carbon footprint. to investigate the feasibility of practical use of quartz sand in plaster and quantify the effect on reducing the embodied energy and carbon footprint, a total of 30 plaster mixes with quartz sand content varying from 0% to 20% at various water/solid ratios were produced for laboratory testing, and the embodied energy and carbon footprint of each plaster mix were quantitatively estimated. results demonstrated that the incorporation of suitable quartz sand in plaster could improve the workability for mixing and trowelling and reduce the embodied energy and carbon footprint as well as the cost at the same time. keywords: carbon footprint, embodied energy, plaster, quartz sand. cement plaster is a mixture of suitable plaster, sand, portland cement and water. it is normally applied to masonry interiors and exteriors to achieve a smooth surface. as a widely used material, the cement plaster brings about major concern of sustainable development for the high embodied energy and carbon footprint derived mainly from cement manufacturing. researchers have devoted enormous efforts to improve the environmental-friendliness and reduce the cost of cement plasters. the research findings in recent years are briefly introduced as follows. rodríguez et al. (2013) had tried adding ladle furnace slag into the plaster and experimentally showed that employing ladle furnace slag as a mineral aggregate would led to increase in density, vapour permeability, porosity, and decrease in adherence, durability and mechanical strength proportionately to the amount of plaster substituted by the ladle furnace slag. their economic study also journal of sustainable architecture and civil engineering 2017/4/21 76 suggested that the ladle furnace slag is viable in terms of cost-effectiveness and may be applied as plaster mortars for use in masonry. aciu et al. (2014) illustrated that adding paper waste into plaster mortar could produce mortar with compressive strength falling in the respective range of category cs i or cs ii in accordance with british standard bs en 998-1. molnar et al. (2015) proved that using waste glass at 25% and 50% sand replacement levels yielded comparable physical and mechanical properties to the control sample and were the most suitable as plaster mortars, and they concluded that such mortars containing waste glass can be used as plaster mortars. andres et al. (2016) attempted to prepare plaster with clay and straw, which is waste from agriculture and most often is burnt in the fields with carbon dioxide emitted. they found that addition of straw would lower the mechanical strengths. molnar and manea (2016) demonstrated that the plaster mortar with 15% substitution of cement by marble powder has a 28-day compressive strength of approximately 56% of the control plaster mortar mix without marble powder added. they concluded that replacing cement with marble powder can lower the cost of plaster mortar while all values of specific characteristics properties could meet the limits imposed by the standards. torres and matias (2016) reported that replacing sand with residuals from brick or roof tiles or pottery in plaster mortar could result in even higher compressive and flexural strengths. bicer and kar (2017) showed that employing waste expanded polystyrene foam as filling materials in the plaster with resin added to the gypsum could save the building heating and cooling energy at the cost of a lower compressive strength. to lower the embodied energy and carbon footprint of plaster, the content of energy and carbon intensive ingredient, i.e. cement in the plaster shall be reduced with the workability and strength maintained to meet the practical requirements. particularly, bs en 998-1 sets minimum compressive strength value to be 0.4, 1.5, 3.5 and 6 mpa for categories cs i, cs ii, cs iii and cs iv mortar, respectively. as quartz is the second most abundant mineral only behind feldspar in earth’s continental crust (anderson and anderson 2010), the use of quartz sand as cement replacement could be a wise strategy for production of environmental-friendly and economical plaster. however, literature review showed that so far there has been very little study on the possibility of using quartz sand as cement replacement for plaster production. in the present study, the quartz sand was added as partial cement replacement and its effects on the workability and strength were evaluated by trial mixing at different water/solid (w/s) ratios, and the embodied energy and carbon footprint of each sample mix were calculated. finally, the viability of such strategy of using quartz sand as partial cement replacement for plaster production is discussed and appraised. both the ordinary portland cement (opc) and quartz sand were obtained in guangdong province of china. the opc was of strength class 32.5n. the quartz sand used in this study is normal quartz sand ground from natural quartz stone in china. its chemical composition is mainly sio2. the solid densities of the opc and quartz sand had been measured in accordance with british standard bs en 1097-3: 1998 as 3100 kg/m3 and 2600 kg/m3, respectively. the specific surface area of the opc was calculated as 1.14×106 m2/m3 (equivalent to 368 m2/kg) based on the particle size distributions measured by a laser diffraction particle size analyzer. the median particle size value of the opc was measured to be 9.34 μm, while the quartz sand was finer than 180 μm according to the supplier. the embodied energy and carbon footprint of all the materials used are tabulated in table 1. materials experimental programme in this study, a total of 30 plaster mixes with and without quartz sand were produced for workability and strength measurement. the quartz sand content, expressed as a percentage by mass of solid in plaster, was varied from 0 to 20% in increments of 5%; whereas the w/s ratio, expressed as a ratio by mass, was varied from 0.35 to 0.60 in increments of 0.05. hence, there were 5 different quartz sand contents and 6 different w/s ratios. altogether 5×6 = 30 mixes were produced for 77 journal of sustainable architecture and civil engineering 2017/4/21 test methods test results testing. all sample preparation and testing procedures were carried out in a laboratory maintained at a temperature of 24±2°c. the workability of the plaster mixes is represented by the semi-dynamic and dynamic flowability, which could reflect the ease of trowelling. the semi-dynamic flowability was measured in terms of the flow spread using the mini slump cone test (okamura et al. 2000). the dynamic flowability was measured in terms of the flow rate using the marsh cone test (aїtcin 1998). the mini slump cone adopted was the same as that used by okamura and ouchi (2003), whereas the marsh cone adopted was the same as that specified in british standard bs en 445: 1997. to measure the strength, three 70.7 mm cubes were made from each plaster sample. the cubes were made by placing the fresh mix into a cube mould. at one day after casting, the moulds were removed. the strength result of each plaster mix was taken as the average strength of three cubes tested at the same time. 1. workability the flow spread results are plotted against the w/s ratio for various quartz sand contents in fig. 1. from the flow spread curves, it is evident that the addition of quartz sand as cement replacement gradually increased the flow spread of the plaster mix. for instance, the addition of 20% quartz sand increased the flow spread from 23.0 to 77.5 mm at a w/s ratio of 0.40 and increased the flow spread from 147.5 to 171.0 mm at a w/s ratio of 0.50. during the flow spread measurement, no bleeding occurred for all the plaster mixes in this study. this observation indicated that at a w/s ratio not fig. 1 variation of flow spread with w/s ratio at various quartz sand contents fig. 2 variation of flow rate with w/s ratio at various quartz sand contents 0 50 100 150 200 250 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 fl ow s pr ea d (m m ) w/s ratio qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 0 20 40 60 80 100 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 fl ow ra te (m l/s ) qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 0 20 40 60 80 100 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 fl ow ra te (m l/s ) w/s ratio qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% higher than 0.60, the addition of up to 20% quartz sand as cement replacement could improve the workability and would not lead to bleeding. likewise, the flow rate results are plotted against the w/s ratio for various quartz sand contents in fig. 2. from the flow rate curves, it is obvious that the addition of quartz sand as cement replacement gradually increased the flow rate of the plaster mix. for instance, the addition of 20% quartz sand increased the flow rate from 36.3 to 72.8 ml/s at a w/s ratio of 0.50 and increased the flow rate from 65.3 to 94.7 ml/s at a w/s ratio of 0.60. the increase in flowability due to the addition of quartz sand may be attributed to the significant decrease in specific surface area of the solid when cement was partially replaced by quartz sand, which at the journal of sustainable architecture and civil engineering 2017/4/21 78 same water content tends to increase the water film coating the solid particles in the plaster mix. generally, the increase in both flow spread and flow rate were proportionally larger at low w/s ratio. this is because addition of quartz sand would increase the packing density of the solid mix by widening the particle size distribution range, and would at the same water content provide proportionally more excess water (the water in excess of that required to fill voids between solid particles) at low w/s ratio (kwan and chen 2013). 2. strength the 28-day compressive strength results are plotted against the w/s ratio for various quartz sand contents in fig. 3. results showed that the strength decreased as the w/s ratio increased, and that the addition of quartz sand as cement replacement decreased the strength. these observations are in accordance with the expectations. it is noted that the decrease in strength due to addition of quartz sand was proportionally larger at higher w/s ratio. this is because at low w/s ratio, water would be the limiting reactant of hydration reaction and there would be relatively large amount of unhydrated fig. 3 variation of 28-day strength with w/s ratio at various quartz sand contents table 1 embodied energy and carbon footprint per unit weight of materials item embodied energy (kj/kg) carbon footprint (kg co2/kg) opc 4.500 0.730 quartz sand 0.850 0.020 water 0.010 0.001 cement, replacing cement by quartz sand would decrease proportionally less amount of hydrated cement. in fig. 3, a dotted line is drawn at the strength level of 6 mpa, which is the required strength of mortar to be classified as the highest category cs iv according to bs en 998-1. it should be noted that a compressive strength below 6 mpa may still satisfy the requirements of other categories, 0 5 10 15 20 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 28 -d ay s tr en gt h (m pa ) w/s ratio qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 0 1000 2000 3000 4000 5000 6000 7000 8000 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 e m bo di ed e ne rg y (k j/ m 3 ) w/s ratio qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% for example, category cs i requires a strength of 0.4 to 2.5 mpa and category cs ii requires a strength of 1.5 to 5.0 mpa. it can be seen from the results that addition of quartz sand up to 20% at w/s < 0.50 or up to 10% at w/s < 0.60 could produce plaster mixes meeting the strength requirement of category cs iv. all the plaster mixes produced in this study meet the strength requirement of at least category cs ii. 3. embodied energy and carbon footprint the manufacturing of cement involves heating of limestone to incept fusion of clinker. this process emits a lot of carbon dioxide and aggravates global warming. according to mehta and walters (2008), the production of one ton of cement releases approximately 0.75 ton of carbon dioxide gas. on this basis, mehta and meryman (2009) estimated that cement production accounts for 6-7% of the total global greenhouse gas emission from all anthropogenic sources. this situation may become even worse because the economic growth of developing countries is likely to boost the demand of cement. compared to cement, quartz sand is more energy efficient and environmental-friendly. typical values of embodied energy and carbon footprint per unit weight of opc, quartz sand and water are listed in table 1 (hammond and jones 2008). clearly, by replacing part of 79 journal of sustainable architecture and civil engineering 2017/4/21 the cement with quartz sand, the embodied energy and carbon footprint of plaster can be substantially reduced. such beneficial effects are quantitatively evaluated in the following. the embodied energy of the plaster mixes is evaluated and plotted against the w/s ratio for various quartz sand contents in fig. 4. results showed that addition of 20% quartz sand could reduce the embodied energy by 17.3% to 17.7% for the range of w/s ratios adopted in this study. likewise, the carbon footprint of the plaster mixes is evaluated and plotted against the w/s ratio for various quartz sand contents in fig. 5. results showed that addition of 20% quartz sand could reduce the carbon footprint by 20.5% to 20.9% for the range of w/s ratios adopted in this study. fig. 4 variation of embodied energy with w/s ratio at various quartz sand contents fig. 5 variation of carbon footprint with w/s ratio at various quartz sand contents 0 5 10 15 20 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 28 -d ay s tr en gt h (m pa ) w/s ratio qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 0 1000 2000 3000 4000 5000 6000 7000 8000 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 e m bo di ed e ne rg y (k j/ m 3 ) w/s ratio qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 0 200 400 600 800 1000 1200 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 c ar bo n fo ot pr in t ( kg c o 2/ m 3 ) w/s ratio qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 0 5 10 15 20 0 20 40 60 80 100 28 -d ay s tr en gt h (m pa ) flow rate (ml/s) qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% it is apparent from the above results that the use of quartz sand as cement replacement in plaster production would improve the workability, lower the strength, reduce the embodied energy and carbon footprint. from the practical perspective, a relatively high workability is beneficial for the mixing and trowelling processes, while the strength is less important given that the required mindiscussion 0 200 400 600 800 1000 1200 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 c ar bo n fo ot pr in t ( kg c o 2/ m 3 ) w/s ratio qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 0 5 10 15 20 0 20 40 60 80 100 28 -d ay s tr en gt h (m pa ) flow rate (ml/s) qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% imum strength is achieved. to gain insight into the relationship between workability and other properties of plaster, the variation of 28-day strength with flow rate performance at various quartz sand contents is plotted in fig. 6, in which the dotted line indicates the minimum strength requirement of category cs iv mortar, i.e. 6 mpa. the concurrent strength and flow rate performance curves show that rational addition of quartz fig. 6 concurrent strength and flow rate performance journal of sustainable architecture and civil engineering 2017/4/21 80 sand to produce plaster can under a necessary strength requirement improve the workability for easier and homogeneous mixing and handling, and reduce the embodied energy and carbon footprint. the variations of embodied energy and carbon footprint with flow rate performance at various quartz sand contents are plotted in fig. 7 and fig. 8, respectively. these concurrent embodied energy/carbon footprint and flow rate performance curves indicate that the use of quartz sand can significantly lower the energy cost and carbon dioxide emission for sustainable development with even improved workability. overall, the use of quartz sand for plaster production could under a necessary strength requirement improve the workability, reduce the emfig. 7 concurrent embodied energy and flow rate performance fig. 8 concurrent carbon footprint and flow rate performance 4000 4500 5000 5500 6000 6500 7000 0 20 40 60 80 100 e m bo di ed e ne rg y (k j/ m 3 ) flow rate (ml/s) qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 600 650 700 750 800 850 900 950 1000 1050 1100 0 20 40 60 80 100 c ar bo n fo ot pr in t ( kg c o 2/ m 3 ) flow rate (ml/s) qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 4000 4500 5000 5500 6000 6500 7000 0 20 40 60 80 100 e m bo di ed e ne rg y (k j/ m 3 ) flow rate (ml/s) qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% 600 650 700 750 800 850 900 950 1000 1050 1100 0 20 40 60 80 100 c ar bo n fo ot pr in t ( kg c o 2/ m 3 ) flow rate (ml/s) qs = 0% qs = 5% qs = 10% qs = 15% qs = 20% bodied energy and carbon footprint, and reduce the cost at the same time. finally, it is the authors’ view that the use of quartz sand for performance improvement and sustainable development should not be limited to plaster. in fact, since the quartz sand has a particle size larger than the opc and smaller than fine aggregate, it should be able to increase the packing density of solid skeleton in the mortar and mortar phase in concrete, and thus improve the performance (aїtcin et al. 2016). future research along this line is highly recommended. conclusions experimental investigation on using quartz sand to produce low embodied energy and carbon footprint plaster has been performed. on the basis of the experimental results, it is concluded that the rational use of quartz sand as cement replacement can, under a necessary strength requirement of given mortar category, improve the workability to ease the mixing and trowelling, reduce the embodied energy and carbon footprint for better sustainability, and at the same time reduce the cost for more affordable construction. further research to capitalise the beneficial effects of utilising quartz sand is recommended. acknowledgment the work presented in this paper was supported by funding from guangzhou science research project (project no. 201607010329), college and hospital research platform of foshan city (project no. 2016ag100341), and marie skłodowska-curie actions of the european commission (project no. 751461). 81 journal of sustainable architecture and civil engineering 2017/4/21 aciu c., varvara d.a.i., cobirzan n., balog a. recycling of paper waste in the composition of plastering mortars. procedia technology, 2014; 12: 295300. https://doi.org/10.1016/j.protcy.2013.12.489 aïtcin p.-c. high-performance concrete. london and new york: e&fn spon; 1998. https://doi. org/10.4324/9780203475034 aïtcin p.-c., wilson w., mindess s. increasing the strength of concrete made with blended cements. concrete international, 2016; 38(8): 49-52. anderson r.s., anderson s.p. geomorphology: the mechanics and chemistry of landscapes. cambridge: cambridge university press; 2010. https:// doi.org/10.1017/cbo9780511794827 andres d.m., manea d.l., fechete r., jumate e. green plastering mortars based on clay and wheat straw. procedia technology, 2016; 22: 327-334. https://doi.org/10.1016/j.protcy.2016.01.105 bicer a., kar f. thermal and mechanical properties of gypsum plaster mixed with expanded polystyrene and tragacanth. thermal science and engineering progress, 2017; 1: 59-65. https://doi.org/10.1016/j. tsep.2017.02.008 hammond g.p., jones c. inventory of carbon & energy (ice). bath: university of bath; 2008. kwan a.k.h., chen j.j. adding fly ash microsphere to improve packing density, flowability and strength of cement paste. powder technology, 2013; 234: 1925. https://doi.org/10.1016/j.powtec.2012.09.016 mehta p.k., meryman h. tools for reducing carbon emissions due to cement consumption. structures, 2009; 1: 11-15. mehta p.k., walters m. roadmap to a sustainable concrete construction industry. the construction specifier, 2008; 61(1): 48-57. molnar l.m., manea d.l. new types of plastering mortars based on marble powder slime. procedia technology, 2016; 22: 251-258. https://doi. org/10.1016/j.protcy.2016.01.076 molnar l.m., manea d.l., aciu c., jumate e. innovative plastering mortars based on recycled waste glass. procedia technology, 2015; 19: 299-306. https://doi.org/10.1016/j.protcy.2015.02.043 okamura h., ouchi m. self-compacting concrete. journal of advanced concrete technology, 2003; 1(1): 5-15. https://doi.org/10.3151/jact.1.5 okamura h., ozawa k., ouchi m. self-compacting concrete. structural concrete, 2000; 1(1): 3-17. https://doi.org/10.1680/stco.2000.1.1.3 rodríguez a., gutiérrez-gonzález s., horgnies m., calderón v. design and properties of plaster mortars manufactured with ladle furnace slag. materials and design, 2013; 52: 987-994. https://doi. org/10.1016/j.matdes.2013.06.041 torres i., matias g. sustainable mortars for rehabilitation of old plasters. engineering structures, 2016; 129: 11-17. https://doi.org/10.1016/j.engstruct.2016.07.009 about the authors jiajian chen assoc. professor foshan university, department of civil engineering main research area high-performance concrete, environmentallyfriendly concrete address 18 jiangwan rd, foshan city, guangdong province, china tel. +86-13450891042 e-mail: chenjiajian@ fosu.edu.cn pui-lam ng adjunct professor vilnius gediminas technical university, faculty of civil engineering main research area sustainable concrete materials and structures, concrete science and nanotechnology, high-performance cementitious materials address sauletekio al. 11, vilnius lt-10223, lithuania tel. +370-62423921 / +852-95875310 e-mail: irdngpl@gmail. com roman jaskulski assist. professor warsaw university of technology, faculty of civil engineering, mechanics and petrochemistry main research area thermal properties of concrete, sustainable concrete materials, recycling and re-use of industrial waste in cement composites address 17 łukasiewicza st., 09-400 płock, poland tel. +48-243672182 e-mail: roman. jaskulski@pw.edu.pl wojciech kubissa assist. professor warsaw university of technology, faculty of civil engineering, mechanics and petrochemistry main research area sustainable development in concrete technology, materials engineering, civil engineering address 17 łukasiewicza st., 09400 płock, poland tel. +48-242626254 e-mail: wojciech. kubissa@pw.edu.pl references journal of sustainable architecture and civil engineering 2015/2/11 32 jsace 2/11 journal of sustainable architecture and civil engineering vol. 2 / no. 11 / 2015 pp. 32-40 doi 10.5755/j01.sace.11.2.12459 © kaunas university of technology received 2015/01/07 accepted after revision 2015/04/02 dimensioning of solar thermal systems for multifamily buildings in lithuania: an optimisation study dimensioning of solar thermal systems for multifamily buildings in lithuania: an optimisation study rokas valančius*, andrius jurelionis, juozas vaičiūnas kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania eugenijus perednis lithuanian energy institute, laboratory of renewable energy breslaujos str. 3, kaunas lt-44403, lithuania *corresponding author: rokas.valancius@ktu.lt http://dx.doi.org/10.5755/j01.sace.11.2.12459 small-scale solar thermal domestic hot water (dhw) systems in lithuania can produce up to 523 kwh per year per one square meter of solar collector area. it is therefore one of the most common solar thermal applications in the country with the expected payback period of approximately 10 years. however, the number of solar water heating systems (swh) installed in the renovated multi-family buildings is quite limited. on the other hand, the potential of integrating solar thermal systems in these buildings is much higher as dhw usage during the day is more uniform in multi-family buildings compared to the singlefamily houses. this aspect brings out a higher solar energy share without adding additional volume to the hot water storage tank. simplified optimization tools for solar collector area selection, volume selection for the accumulation tank, installation costs and payback period estimation are required for promoting swh systems for dhw production in multi-family buildings. this paper deals with dhw consumption analysis in multi-family buildings in lithuania as well as modelling of solar thermal systems to produce a tool for decision makers for preliminary analysis of swh systems integration in renovated multi-family buildings. the main target group for the tool developed are multi-family buildings connected to district heating network. simulation software “t*sol 5.0 pro” was used for swh systems performance evaluation as well as financial analysis of swh system alternatives. keywords: solar thermal systems; water consumption; multi-family buildings; optimisation; dimensioning tool. 33 journal of sustainable architecture and civil engineering 2015/2/11 solar water heating (swh) is one of the most common solar thermal applications. in 2012 the world added 55.4 gwth (more than 79 million m²) of solar heat capacity (ren21, 2014) and the most popular types of solar collectors in eu and switzerland are flat plate (89%) and evacuated tube (11%) collectors (estif, 2013). only about 8200 m² (5740 kwth) of glazed solar collectors were installed till the end of 2013 in lithuania and the applications were mostly limited to single-family buildings (estif, 2013). yet, average global solar irradiation in lithuania is similar to the irradiation levels in such countries as germany, austria, denmark, poland, latvia and estonia with the annual potential of solar energy yield of approx. 1000 kwh/m². the daily potential in the country varies from 0.55 kwh in january to 5.8 kwh in june, therefore, almost the whole irradiated solar energy can be collected during the warm period of the year (from april till october). due to this fact, solar water heating (swh) systems are most efficient in domestic hot water (dhw) applications in lithuania (kytra, 2006). nevertheless, technical-economic potential of solar heat energy production in the country reach up to 1.5 twh/year (129 ktoe). according to the meteorological data, the values of expected solar energy yield are increasing during the last decade as solar irradiation increased by 7% during the years of 2005 to 2014 compared to the long-term statistical data. some studies in lithuania and in other similar countries of similar climate showed that small and medium scale solar dhw systems with flat plate or evacuated tube collectors can produce from 335 to 523 kwh/m² of thermal energy per year and the payback time of these systems is over 8 years without the subsidies. the potential of swh for domestic hot water production is quite high, however, the support from government and eu funds is still necessary in most cases to achieve reasonable payback (adomavičius, 2010; ayompe and duffy, 2013; hugo and zmeureanu, 2012; jonynas and valančius, 2010; perednis et al., 2007; valančius et al., 2015). the number of medium-scale shw systems in lithuania is still relatively low at the time and represent the potential direction for development of these systems. there are several medium-scale shw systems installed in the country varying from 60 to 204 m² of total solar panel area. most of these systems are installed in the past few years in public buildings, hospitals and industrial facilities. the oldest still operational shw system 77 m² was installed in 2002 in children sanatorium “žibutė” (kačerginė). however, it took 10 years for the first swh system to be installed in multi-family building as the first such system was launched only in 2012 (katinas et. al., 2013; karbauskaitė and perednis, 2011; valančius et al., 2015). multi-family buildings represent one of the major potential for swh installation as it is one of the best renewable energy alternatives for these buildings (adomavičius, 2010; diliunaite, 2013). more uniform dhw usage during the day is common for multi-family buildings compared to the single-family houses. it is related to variability of occupants and their hot water consumption habits and this aspect brings out a higher solar energy share without adding additional volume to the accumulation tank. moreover, dhw consumption throughout the day presents the possibility to keep lower temperatures in the collectors even during periods of high solar radiation. multi-family buildings provide a possibility to connect several users to the same combined swh system, therefore the heat losses due to transformation and transportation of hot water will be incurred to a lesser extent during the system operation (žandeckis et al., 2011). the market growth of solar thermal systems and photovoltaics in europe depends on the policy of the governments towards the use of solar energy systems. considering the targets of eu for renewables in the 20-20-20 programme, solar energy systems can play a significant role in many countries (caouris et al., 2012). when discussing multi-family buildings, government grants of up to 40% are currently offered in lithuania for energy saving measures and usage of renewables in renovated buildings. introduction journal of sustainable architecture and civil engineering 2015/2/11 34 the major part of thermal energy used in multi-family buildings in lithuania are supplied via the district heating network. 72.4% from all district heating produced energy was used for household purposes in 2012 (lšta, 2013) and the price in different cities varies in the range from 0,458 eur/ kwh to 0,901 eur/kwh (lšta, 2015). the multi-family building stock in lithuania can contribute to reduction of both greenhouse gas (ghg) emissions and energy consumption of the country significantly by integrating medium-scale swh systems under the framework of renovation initiatives. relation between installation costs and area of the flat plate solar collectors (including heat storage tanks and auxiliary equipment) can vary in the range from 600 to 150 eur/m² in shw from 10 m² to 10000 m². the installation costs, annual maintenance and repairs costs vary in wide range depending on type of solar collectors and other equipment as well, but in general, larger swh installations are relatively cheaper to maintain than small-scale swh systems (andrews et al., 2012; leutgöb and rammerstorfer, 2013). additional costs for design of the systems in lithuania add up to 8% from the installations costs. in some cases installing swh systems in existing buildings can cost up to 20% more than in new buildings. several studies showed that despite the fact that evacuated tube and flat plate collectors are considered to be suitable for solar heating in central european climates, the evacuated tube collectors does not reach the additional expected energy yield (trinkl et al., 2005). flat plate collectors and evacuated tube collectors produce the same amount of energy from effective area during summer season in lithuania, but it is much less expensive to use flat collectors in most cases (ambrulevičius, 2005; jonynas et. al., 2011). in recent years price of evacuated tube collectors is slowly decreasing and they are becoming increasingly popular. but there is still lack of efficiency and financial analysis for these collectors at the moment. the guidelines performed in germany showed that in general meeting 50% of the annual energy needs for dhw requires a collector area of 1-1.5 m² per apartment and about 50-60 l of solar heat storage per m² of collector surface (solarge, 2007). the studies performed by rodríguez-hidalgo et al. (2012) and kulkarni et al. (2007) showed that the optimal storage tank volume for medium-scale swh systems are about 50 liters for 1 m² of collector field absorber area. considering the results of the above given studies and regional practice, decision making can be simplified by creating a user-friendly optimization tools for solar collector area selection, volume selection for the accumulation tank, installation costs and payback period estimation. development of such a tool would promote medium-scale swh systems in multi-family building sector. the aim of this study was to simulate the performance of swh systems for dhw production for lithuanian climatic conditions and to produce a user-friendly tool to be used in decision making and quick estimation of performance of solar thermal applications. the main target group for the tool developed are multi-family buildings connected to district heating network. simulation software “t*sol 5.0 pro” was used for swh systems performance evaluation and the chart for estimation of swh projects was developed. solar energy yield and district heating energy price of kaunas city was selected for the study. several assumptions and boundary conditions were utilized to develop the tool for user-friendly estimation of swh system performance. typical schemes of swh systems selected for the study are presented in fig. 1 and can be characterized as hybrid solar thermal dhw systems. both system “a” and system “b” are connected to district heating network as well as solar collectors. antifreeze is used in the solar collector loop for heat transfer into the hot water storage tank. system “a” represents the simpler solution as cold water (cw) is stored in hot water tank while in case of the system “b” hot water tank works as heat accumulation device. the function of heat methods 35 journal of sustainable architecture and civil engineering 2015/2/11 exchanger in the system “a” is to heat up the water in case of too low dhw temperature. this unit is also present in the system “b”. however, the system “b” is equipped with the secondary heat exchanger which separates hot water tank loop from dhw loop. therefore, no potable water is stored in the hot water tank. this ensures higher hygienic parameters of the dhw and lowers the risk of bacterial growth in the tank itself. both system “a” and “b” can be efficiently used in multi-family buildings. however, in this study the system “b” was selected as a better alternative due to lower risks of malfunction in case of insufficient maintenance. groundwater of average temperature equal to +8°c is used in lithuania in water supply systems of buildings. heating it up to +52°c is required for dhw supply. the energy demand for 1 m³ of dhw preparation was assumed to be 51 kwh in the simulations. the inclination angle of the solar collector should be 30°-60° and orientation to the south with the error of ± 20° to achieve maximum efficiency of the solar collectors should be ensured (genutis, 2008). orientation of the solar collector to the south with the inclination angle of 45°was used for system “a” system “b” fig. 1 typical schemes of hybrid swh system connection to domestic hot water distribution system and district heating network. groundwater of average temperature equal to +8°c is used in lithuania in water supply systems of buildings. heating it up to +52°c is required for dhw supply. the energy demand for 1 m³ of dhw preparation was assumed to be 51 kwh in the simulations. the inclination angle of the solar collector should be 30°-60° and orientation to the south with the error of ± 20° to achieve maximum efficiency of the solar collectors should be ensured (genutis, 2008). orientation of the solar collector to the south with the inclination angle of 45°was used for simulations of swh systems in this study. total annual global irradiation in kaunas city (55°32'0"n / 25°6'0"e) is equal to 984.9 kwh/m² which was the value used for performance simulations of swh systems. high efficiency flat plate collectors (optical efficiency of collector 0 80 %) were selected for the simulations. the other parameters used for modeling swh systems are presented in table 1. simulations were carried out by using the software “t*sol 5.0 pro”. this simulation tool with weather data and extensive product databases allows dynamic calculation of dhw fractions, energy balance and system efficiency as well as to design shw systems to achieve economic efficiency, fuel savings, avoided co2 emissions. system “a” dhw storage tank sol ar col lector heat exchanger pum p connect ion to dist rict heat ing network dhw col d water supply system “b” heat storage tank sol ar col lector heat exchangers pum p connect ion to dist rict heat ing network col d water supply dhw journal of sustainable architecture and civil engineering 2015/2/11 36 simulations of swh systems in this study. total annual global irradiation in kaunas city (55°32‘0“n / 25°6‘0“e) is equal to 984.9 kwh/m² which was the value used for performance simulations of swh systems. high efficiency flat plate collectors (optical efficiency of collector η 0 80 %) were selected for the simulations. the other parameters used for modeling swh systems are presented in table 1. life span, years 20 specific fuel costs, eur/kwh 0.07 specific electricity costs, eur/kwh 0.14 index for energy prices, % per year 3.0 interest capital, % 2.5 running costs, % 1.5 simulations were carried out by using the software “t*sol 5.0 pro”. this simulation tool with weather data and extensive product databases allows dynamic calculation of dhw fractions, energy balance and system efficiency as well as to design shw systems to achieve economic efficiency, fuel savings, avoided co 2 emissions. the potential of swh was estimated by using the dhw usage data from 15 multi-family buildings in kaunas, lithuania constructed between the years of 1946 to 1990. number of flats and floors of the buildings varied in the range of 40-120 and 5-12 respectively. vast majority of the analyzed flats were 30 to 90 m² area 2 bedroom apartments. the average number of occupants in one apartment was approx. 3. table 1 parameters used for the simulations of swh systems. the potential of swh was estimated by using the dhw usage data from 15 multi-family buildings in kaunas expressed in monthly energy demand in kwh. the average consumption of dhw of temperature approx. equal to +53.5°c in the analyzed buildings was 2.47 m³ (±9.1%) per month and was lower compared to cold water consumption 3.86 m³ (±8.1%) per month. average monthly consumption of both cold and hot water was more or less stable during the year with the exception of summer season when the water usage has decreased. monthly average energy demand for dhw heating, solar irradiation in kaunas as well as the potential of solar energy yield considering the conversion factor of swh system are presented in fig. 2. it can be observed from figure 2 that the typical solar collector area for one apartment should be around 1.7 m² to reach approx. 100% solar fraction in summer time. results fig. 2 monthly average demand for dhw heating in 15 multi-family buildings in kaunas (55°32‘0“n / 25°6‘0“e), solar irradiation (kytra, 2006) and expected solar energy yield of swh system 0 20 40 60 80 100 120 140 160 1 2 3 4 5 6 7 8 9 10 11 12 month kw h 0 20 40 60 80 100 120 140 160 kw h/ m 2 average energy demand for dhw production in multi-family buildings total annual global irradiation in kaunas expected average energy production by swh system per m² of absorber area fig. 2. monthly average demand for dhw heating in 15 multi-family buildings in kaunas (55°32'0"n / 25°6'0"e), solar irradiation (kytra, 2006) and expected solar energy yield of swh system. 20 simulations were performed by using the “t*sol 5.0 pro” software to obtain relations between major parameters required to optimize swh systems for dhw applications in multi-family buildings in lithuania. the results of the simulations were expressed in the form of a chart utilizing several steps of swh system estimation and are presented in figure 3. 37 journal of sustainable architecture and civil engineering 2015/2/11 20 simulations were performed by using the “t*sol 5.0 pro” software to obtain relations between major parameters required to optimize swh systems for dhw applications in multi-family buildings in lithuania. the results of the simulations were expressed in the form of a chart utilizing several steps of swh system estimation and are presented in fig. 3. fig. 3 swh performance estimation chart comprising dhw usage per average apartment, optimal area of solar collectors and storage tank, required investment (without design costs) and payback period of the solar thermal system for multi-family buildings in lithuania the entry point of the chart is based on average monthly dhw consumption which is followed by selection of solar fraction for dhw. this is the parameter which can be selected by the decision maker as an additional input, namely the percentage of annual energy demand for dhw which will be covered by the swh system (values from 30% to 60% were analyzed). active surface area of solar collector, storage tank volume, expected system efficiency as well as required investment are obtained as a result. the payback period of the selected system can be obtained by knowing the percentage of subsidies for shw system installation (values from 0% to 40% were used in the chart). an example for such selection is provided in figure 3 and the input and output data for this case is provided in table 2. simulations showed that shw systems in lithuania can reduce ghg emissions from 92 to 147 kg co 2 /m² absorber per year, when shw systems efficiency varies from 35 to 55%. journal of sustainable architecture and civil engineering 2015/2/11 38 analysis of domestic hot water consumption data showed that the average dhw demand for multi-family buildings in lithuania is equal to 2.47 m³ per month. according to the meteorological data for solar irradiation, active collector area of 1.7 m² and 90 l of heat storage tank volume per apartment are required to meet 50% of the annual energy needs for dhw production. 20 cases were simulated by using the “t*sol 5.0 pro” software to obtain relations between major parameters required to optimize swh systems for dhw applications in multi-family buildings in lithuania. swh performance estimation chart comprising dhw usage per average apartment, optimal area of solar collectors and storage tank, required investment and payback period of the solar thermal system was developed as a result. the chart can be used by decision makers as a quick estimation tool for shw installations in multi-family buildings. it may contribute to promoting swh applications in multi-family building sector. simulations showed that shw systems in lithuania can reduce ghg emissions from 92 to 147 kg co 2 /m² absorber per year, when shw systems efficiency varies from 35 to 55%. it is important to note that the chart and data provided in this study is based on dhw consumption in the existing buildings in lithuania, however the optimization procedure is solely based on simulation results. numerical calculations show high potential of swh application for dhw production in multi-family buildings and the data from existing buildings should be included in future studies to evaluate the difference between the results of the simulations and actual data from case studies. at the moment there is still lack of operational installations of this type equipped with monitoring systems to perform such an analysis. table 2 input / output parameters and the steps of the procedure for the example case step no input output parameter value parameter value entry 1 average monthly dhw consumption 2.47 m³ ↓ 2 solar fraction for dhw 50% 3 ↓ efficiency of swh system 40-45% 4 storage tank volume per apartment 90 l 5 surface area of solar collectors per apartment 1.7 m² 6 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dx.doi.org/10.2478/v10145-011-0020-4 rokas valančius lecturer kaunas university of technology, department of building energy systems main research area renewable energy, indoor climate, energy performance in buildings address studentų st. 48, lt-51367 kaunas, lithuania tel. +37068010000 e-mail: rokas. valancius@ktu.lt andrius jurelionis assoc. professor kaunas university of technology, department of building energy systems main research area indoor climate, hvac technologies, energy performance in buildings, renewable energy address studentų st. 48, lt-51367 kaunas, lithuania tel. +37068391004 e-mail: andrius. jurelionis@ktu.lt juozas vaičiūnas lecturer kaunas university of technology, department of building energy systems main research area water supply and disposal systems, hydronic performance of hvac systems, structural stability of buildings address studentu st. 48, lt-51367 kaunas, lithuania tel. +37061556760 e-mail: juozas. vaiciunas@ktu.lt eugenijus perednis senior research associate lithuanian energy institute, laboratory for renewable energy and energy efficiency main research area energy efficiency of buildings, renewable energy address breslaujos st. 3, 44403 kaunas, lithuania tel. +37037401813 e-mail: saule@mail. lei.lt about the authors 83 journal of sustainable architecture and civil engineering 2015/4/13 methodology of visual pollution assessment for natural landscapes corresponding author: jurate.kamicaityte@ktu.lt http://dx.doi.org/10.5755/j01.sace.13.4.13820 jūratė kamičaitytė-virbašienė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania giedrė godienė a. baranausko st. 8, lt-04224 vilnius, lithuania gintas kavoliūnas vilnius college of design, kauno st. 34, lt-03202 vilnius, lithuania in 2014 the ministry of environment of the republic of lithuania initiated creation of methodology of the assessment of visual pollution to natural landscape complexes and objects. in order to prepare the methodology legal (international and national level) and theoretical framework (world-wide and lithuanian experience in the field of visual impact assessment (via) and assessment of landscape visual-aesthetic potential) was analysed and evaluated. using the method of logical analogy and considering the results of analysis of legal and theoretical framework of via, and peculiarities of lithuanian landscape, the concept of visual pollution and the main methodological stages of visual pollution assessment (vpa) for natural landscapes were proposed. the authors of the methodology state that the assessment of visual pollution should be based on: the establishment of the overall landscape character, visual character, visual capacity, and other aspects as the starting point for the evaluation of visual pollution; assessment of visibility of a pollution object; description of physical, visual and other characteristics of the pollution object; evaluation of negative visual impact (visual pollution) according the level of contrast of physical, visual and other characteristics of landscape and the pollution object. keywords: natural landscape, visual pollution, visual impact assessment, methodology. in 2014 the ministry of environment of the republic of lithuania initiated creation of methodology of the assessment of visual pollution to natural landscape complexes and objects. developing the methodology the legal framework (international and national legislation) of the assessment of visual pollution (negative visual impact) to landscape was analysed. the statements of eu directives (85/337/eec (amendment 2014/52/eu); 2001/42/ec), european landscape convention (2002), the recommendation cm/rec(2008)3 of the committee of ministers to member states on the guidelines for the implementation of the european landscape convention, national political documents (national landscape policy (2004)), studies (national landscape study (2013)), laws (law on environment protection (1996), law on protected areas (2001), law journal of sustainable architecture and civil engineering vol. 4 / no. 13 / 2015 pp. 80-88 doi 10.5755/j01.sace.13.4.13820 © kaunas university of technology received 2015/10/10 accepted after revision 2015/11/30 methodology of visual pollution assessment for natural landscapes jsace 4/13 introduction journal of sustainable architecture and civil engineering 2015/4/13 84 on immovable cultural heritage protection (2004), law on the assessment of environmental impact of the planned economic activity (2005), etc.) plans (national landscape management plan (2015)), and other documents were reviewed. the analysis showed that international legal documents create all preconditions for the visual impact assessment (via) at the national level. the national legislation requires the avoidance of visual pollution, but there are no recommendations how to assess visual impact (kamičaitytė-virbašienė et al, 2015). the analysed theoretical framework consisted of lithuanian and world-wide experience in the fields of the assessment of landscape visual-aesthetic potential and visual impact assessment. we analysed theoretical issues of via in united kingdom, united states, germany, spain, new zealand, south african republic, and australia (environmental impact..., 2008; turner, 2003; visual resource... 2001; manual 8431..., 2012; morris and therivel, 2001; guidelines for landscape…, 2002; evaluation of methodologies..., 2012; böhm, 1996; guidelines for..., 2005); reviewed lithuanian experience (scientific works of m. purvinas (1975, 1983a, 1983b, 1990), p. kavaliauskas (2011), r. skorupskas and v. vasilevskaja (2014), j. abromas (2014), etc.). lithuanian and worldwide experience was compared and evaluated considering the concept of visual pollution (negative visual impact) and the necessity of its assessment for natural landscapes. the analysis of experience of foreign countries in the field of via, showed that these countries have validated concepts of landscape visual quality and planned activity or object visual impact assessment; systemic and objective methodological recommendations of visual impact assessment, which are used in practical activities of planning and design. methodologies used by lithuanian authors are well developed theoretically and intended for the overall evaluation of landscape visual quality or via, designation of landscape visual quality classes, evaluation of indicators of visual spaces, establishment of visual resistance and sensitivity of visual spaces (kamičaitytė-virbašienė et al, 2015). though parts of some works can be used for the assessment of visual pollution (negative visual impact), there are no created specific methods suitable for visual pollution assessment (vpa) for natural landscapes. the aim of the paper is to present the concept of visual pollution and the main methodological stages of visual pollution assessment for natural landscapes. after the analysis of legal and theoretical framework in the field of visual impact assessment and assessment of landscape visual-aesthetic potential (kamičaitytė-virbašienė et al, 2015), using the method of logical analogy and considering the results of the analysis and peculiarities of lithuanian landscape, we proposed the main methodological stages of visual pollution assessment (vpa) for natural landscapes. logical analogy has enabled us to formulate scientifically valid notion of visual pollution (negative visual impact), describe the comparative indicators (physical and visual characteristics) of landscape and the object of visual pollution, clarify of the main stages of vpa, and determine the content of each stage of vpa. considering the peculiarities of lithuanian landscape (such as: big variety of landscape types and separate elements, human scale of landscape visual spaces, high degree of fragmentation and quite high level of anthropogenization) we elaborated the content of each stage of vpa. visual pollution in the proposed vpa methodology is understood as negative visual impact of visual pollution object (vpo) on landscape, i.e. the changes of landscape physical components (relief, water bodies, vegetation, and structures and/or installations) and their visual characteristics that determine the change of landscape character and decrease of landscape visual quality and/ or obstruct overview of the valuable natural complexes or objects, diminish visual significance of valuable landscape objects. methods results 85 journal of sustainable architecture and civil engineering 2015/4/13 already existing or designed new landscape elements and their modifications (land surface mounds, excavations, structures and/or installations, greene ry, water bodies, movable objects and so on, or significant increase of the existing buildings volume after reconstruction and maintenance works, changes of architectural forms, colours, lines and textures, etc.) can be assessed as a potential vpo if from the particular observation place they: _ are observed by bigger than 1° vertical viewing angle and bigger than 2,5° horizontal viewing angle; _ obstruct 5 percent or more of the visible image; _ has the potential to: _ change the landscape character; _ reduce landscape visual quality; _ obstruct overview of valuable natural landscape complexes or objects, reduce visual significance of the valuable objects on the landscape. we state that vpa should be mandatory in the protected areas established for the purpose of the protection of landscape or its components, i.e. in all state parks, relevant state and municipal reserves; areas of natural and cultural heritage objects; visual protection zones of state parks and heritage objects; recreational areas; in areas of expressive aesthetic potential designated in the national landscape management plan (2015); in the landscape areas of particularly expressive and medium-sized vertical and horizontal fragmentation with open and semi-open spaces designated in the national landscape study (2013). vpa is recommended in the areas which the municipal authorities have designated as the identity-shaping and/or having significant recreational and/or aesthetic potential; from the observation places in the corridors of national tourism routes. the main proposed methodological stages of vpa for natural landscapes are the following: 1 preparatory stage: description of the observation place, landscape visibility analysis, pho-to-fixation, general evaluation of natural landscape complex or object (common landscape character, valuable characteristics, rarity (exclusivity), protection status, immanent, ecological, historical-cultural, economic, scientific-cognitive, recreational values and meaning to local identity, function, and regulations), detailed assessment of landscape character, visual nature, values, and capacity (objective indicators of landscape components, indicators of visual spaces, visual dominants, accents, landmarks, landscape visual characteristics (scale, lines, visual plans, forms, colours, textures), landscape visual capacity and possible level of visual constrast, evaluation of overal impression). 2 identification of the potential visual pollution: repeated visualization or photo-fixation, visibility evaluation of the potential vpo: designation of vpo visual impact zone, identification of its horizontal and vertical viewing angle, description of physical and visual features of vpo, its function and style, evaluation of the contrast level and comparison of it with the possible level of visual contrast (table 1). preparatory stage. describing the observation place, it is necessary to indicate address and name of the place, shooting point coordinates, the absolute height above the sea level, to describe briefly the analyzed landscape, the main landmarks, to specify direction of the observed view, horizontal and vertical viewing angle, recreational and touristic importance of the observation place. landscape visibility analysis could be performed using gis intervisibility function and designating visual influence zone of the observation place. the area seen from the observation place is our landscape analysis and evaluation unit. performing photo-fixation attention should be paid to atmospheric conditions, time, photo-fixation height, direction, photographic technique, how many shots are done, if shots have to be journal of sustainable architecture and civil engineering 2015/4/13 86 areas with different levels of landscape protection possible levels of visual contrast considerable moderate weak insignificant natural and cultural heritage objects impossible impossible impossible impossible state parks, except zones of economic functional priority impossible impossible impossible possible state and municipal landscape reserves and reserves in which visually perceived landscape components are protected (geological, geomorphological, hydrographical, urban/architectural, etc.) impossible impossible impossible possible visual protection zones of state parks and heritage objects impossible impossible impossible possible recreational areas impossible impossible impossible possible areas of expressive aesthetic potential designated in the national landscape management plan; the landscape areas of particularly expressive and medium-sized vertical and horizontal fragmentation with open and semi-open spaces designated in the national landscape study impossible impossible impossible possible other not protected aesthetically valuable areas impossible impossible possible possible zones of economic functional priority in state parks impossible impossible possible possible other areas possible * possible * possible possible * possible if changing of landscape visual type is permited by the territory planning documents joined, what computer program is used, and other technical data. in the scheme the shooting point, angle and direction should be marked. general evaluation of landscape character should be performed referring to the national landscape study (2013) and using the scheme of physio-morphotops and describing the main landscape elements which are observed. describing function, regulations, and protection status information from state service for protected areas database should be used; referring to the legislation and spatial planning documents properties of protected landscape complexes, restricted and prohibited activities should be specified. elaborating the assessment of landscape character, objective indicators of landscape components have to be established: physiognomic characteristics, height, angle of inclination, specific formations of relief; scale and nature, size, abundance of formations of water bodies; spatial structure, the dominant species, height, size of habitats, abundance of formations of vegetation cover (forests, meadows, wetlands/agricultural land, water plant communities); spatial structure, types, size, abundance of formations, materials used, constructions, historical-cultural significance of structures and installations; ratio of open and planted/built-up area (table 2). the main analyzed quantitative and qualitative indicators of landscape spatial structure that condition landscape visual character are the following (kamičaitytė – virbašienė, 2003, 2011; purvinas, 1975): size, plan configuration, vertical and horizontal closure, the number of ranks of visual spaces (vs) (hierarchy); integrity, naturalness and variety of vs; degree of dominance of vs components (table 3). there is also analyzed the existing material of the research of landscape aesthetic potential: scheme of location of emotio-tops (kavaliauskas, 2011), the scheme of visual structure from the national landscape study (2013), material of the national landscape management plan (2015), the data of territorial planning documents, etc. table 1 possible levels of visual contrast in areas with different levels of landscape protection 87 journal of sustainable architecture and civil engineering 2015/4/13 landscape components objective indicators relief scale and nature height specific formations angle of inclination water bodies scale and nature size abundance of formations vegetation height and size of habitats abundance of formations spatial structure species ratio of open and planted/ built-up area structures and installations size abundance of formations spatial structure, types of structures materials, constructions historicalcultural significance ratio of open and planted/ built-up area indicators of spatial structure characterization of indicators vs size (according viewing radius r, m) r = 50 – 100 m – small vs r = 100 – 500 m – average size vs r = 500 – 2000 m – large vs vs rank place of vs in the hierarchical spatial structure of landscape vs plan configuration simple vs complex vs continuous vs vs horizontal closure (perimeter of vs occupied by visual obstacles) absolute – 90 – 100% big – 85%, average – 65% minimal – 30% vs vertical closure (viewing angle) absolute – 45o (details of the object can be seen) partial closure – 27o (proportions of the object are perceived) partial closure – 18o (object relation with contextual environment and its shape is perceived) expressivity of spatial structure (height of relief and the number of ranks of vs conditions this indicator) big expressivity (hilly with deep valleys landscape with 4-5 ranks of vs) average expressivity (hilly with vallleys landscape with 3 ranks of vs) small expressivity (undulating landscape with 2 ranks of vs) unexpressive structure (plain landscape with 1 rank of vs) vs integrity integral vs fragmented by visual obstacles vs vs naturalness quantity of natural, athropogenizied and anthropogenic components of vs dominance of natural, athropogenizied and anthropogenic components of vs ve variety quantity of vs components location of vs components degree of dominance of vs components dominant components of vs according size, form, colour and texture background components of vs according size, form, colour and texture landscape visual character is also conditioned by landscape visual characteristics: scale, forms, lines, colours and textures of landscape components. there are assessed complexity, expressivity, orientation, and regularity of forms; complexity, curvature, orientation, and intensity of lines; hue, intensity, and brightness of colours; degree of fragmentation, density, regularity, and inner contrast of texture. scale is described as the proportionate size relationship between an object and the surroundings in which it is placed. table 2 the proposed set of landscape components objective indicators table 3. indicators of vs and their characterization acording m. purvinas and p. kavaliauskas journal of sustainable architecture and civil engineering 2015/4/13 88 landscape visual capacity is understood as ability of landscape to integrate new objects without changing its visual character and quality. the main indicators of visual capacity are the following: degree of variety, landscape expressivity, size, horizontal closure, plan configuration, and integrity of vs. the bigger variety and expressivity of landscape, more complex configuration of vs, the bigger closure and fragmentation of vs, the bigger visual capacity of landscape is. there is also proposed expert evaluation of overal impression which helps to identify protected individual features and values of the analyzed area. identification of the potential visual pollution. repeated visualization or photo-fixation has to repeat the conditions of the status quo view (colours, lighting, etc.). anlyzing visibility of the potential vpo, its coordinates, the absolute height above the sea level, distance to the observation place, its width, height, vertical and horizontal viewing angle have to be established. using gis intervisibility function vpo zone of visual influence is designated. the nearer vpo to the viewer, the bigger its vertical and horizontal viewing angle is. the table 4 shows the relationship between the viewing angle and the size of the visual impact. visual impact levels according to the size of the viewing angle maximum vertical viewing angle of vpo height measured from the line of the horizon maximum horizontal viewing angle of vpo width discernible 5` 0,5o 5` 1o visible but insignificant 0,5o – 1o 1o – 2,5o visually significant 1o – 5o 2,5o – 30o clearly dominant 5o – 45o 30o – 120o the next step is description of physical and visual features of vpo, its function and style. there are specified vpo scale, forms, lines, colours, textures; object size, spatial structure, abundance of formations, species (if vpo is vegetation), materials, constructions, etc. the overall visual contrast level (level of visual polution) is derivative of contrast levels of protected landscape and vpo visual properties and materials. it is determined by comparing visual features and materials characteristic to the individual components of the landscape with potential vpo visual characteristics and materials and determining their contrast (table 5). landscape components relief water bodies vegetation structures degree of visual contrast (comparative indicator) c on si de ra bl e m od er at e w ea k in si gn ifi ca nt c on si de ra bl e m od er at e w ea k in si gn ifi ca nt c on si de ra bl e m od er at e w ea k in si gn ifi ca nt c on si de ra bl e m od er at e w ea k in si gn ifi ca nt scale (weight coefficient 2)* forms lines colours (weight coefficient 2)* textures materials overall visual contrast level considerable moderate weak insignificant * scale and colour are the most important factors of visual contrast table 4 the relationship between the viewing angle and the size of the visual impact of vpo table 5 visual contrast rating by visual charcteristics and materials 89 journal of sustainable architecture and civil engineering 2015/4/13 the overall visual contrast level is influenced by the style and function of the new object (potential vpo) as well. for ex.: if a modern building will be built near the historic buildings, their style will create high contrast; if a residential building will emerge in the protected forested landscape, their functions will be fully incompatible (high contrast). it is also necessary to assess what proportion of observed panoramas/protected complex or object potential vpo obstructs. the overall visual contrast can be considerable, moderate, weak or insignificant. depending on the status of landscape protection different level of contrast is permitted (table 1). considerable contrast means that vpo dominates in the landscape, changes the landscape character and strongly reduces visual quality and/or obstructs overview of the valuable natural landscape complexes or objects (covers more than 12% of the visible image) and decreases visual significance of valuable landscape objects. landscape visual pollution is high. moderate contrast means that vpo draws attention, but does not dominate in the landscape (the landscape accents level), results in some changes of the landscape character and reduces the visual quality and/or obstructs overview of the valuable natural landscape complexes or objects (covers 5% 12% of the visible image), decreases visual significance of valuable landscape objects. landscape visual pollution is average. weak contrast means that vpo is visible, but little changes the landscape character and only slightly reduces the visual quality (in some cases it may not reduce if the area is not protected) and/or obstructs overview of the valuable natural landscape complexes or objects (covers up to 5% of the visible image), decreases visual significance of valuable landscape objects. landscape visual pollution is low. insignificant contrast means that the landscape changes are minor, do not draw attention and do not alter the landscape character or reduce visual quality; vpo does not obstruct the view. there is no visual pollution. methodolgical propopsals of vpa are based on the analysis of world-wide and national legal and theoretical framework of via which helped to specify: the main stages in the vpa process and their content, levels of visual contrast, notions of landscape visual capacity, description of the visual characteristics, quantitative and qualitative indicators of visual impact, criteria and indicators of landscape aesthetic potential and visual resistance of vs, etc. the authors of the methodology state that the assessment of visual pollution should be based on: the establishment of the overall landscape character, visual nature, visual capacity, and other aspects as the starting point for the evaluation of visual pollution; assessment of visibility of vpo (designation of vpo visual influence zone, identification of its horizontal and vertical viewing angle); description of physical and visual characteristics of vpo, its function and style; evaluation of negative visual impact (visual pollution) according the level of contrast of physical, visual and other characteristics of landscape and the pollution object. the proposed methodological framework of vpa can be used not only assessing visual pollution for natural landscapes but also assessing possible visual contrast of a new object in a townscape, suburban landscape, etc. it is a good starting point for the preparation of the broader methodological work – guidelines for the visual impact assessment that could be used while preparing spatial plans, projects of urban complexes or even designing separate buildings. this research project was funded by the ministry of environment of the republic of lithuania. we would like to thank colleagues from the landscape division of protected areas and landscape department for their expert advices throughout the preparation of the project. conclusions acknowledgment journal of sustainable architecture and civil engineering 2015/4/13 90 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ministerija, 2015. purvinas m. apie aplinkos vizualinio agresyvumo urbanistinę analizę [about urban analysis of environmental visual aggressiveness]. lietuvos am mokslo darbai. urbanistika ir rajoninis planavimas, 1990, 16: 37–46. purvinas m. kraštovaizdžio architektūrinės analizės taikymas projektavime [application of landscape architectural analysis in design]. lietuvos tsr architektūros klausimai, 1983a, 8(1): 52. purvinas m. kraštovaizdžio erdvinės struktūros pirminiai vienetai ir jų galimos charakteristikos [pri91 journal of sustainable architecture and civil engineering 2015/4/13 mary units of landscape spatial structure and their possible characteristics]. ltsr aukštųjų mokyklų mokslo darbai. statyba ir architektūra, xiv. architektūra ir miestų statyba, 1975, 4: 5–21. purvinas m. subjektyvus kraštovaizdžio vertinimas [subjective landscape assessment]. lietuvos tsr architektūros klausimai, 1983b, 8(1): 60–67. recommendation cm/rec(2008)3 of the committee of ministers to member states on the guidelines for the implementation of the european landscape convention. 2008. available at: http://www.coe.int/t/ dg4/cultureheritage/heritage/landscape/versionsorientation/anglais.pdf (accessed 20 may 2015). turner t. landscape planning and environmental impact design. london, 2003. vasilevskaja v., skorupskas r. esminiai kraštovaizdžio vizualinės struktūros vertinimo aspektai [essential aspects of landscape visual structure assessment]. geografija, 2014, 50(1): 11–22. visual resource management: information document. washington: bureau of land management. 2001. available at: www.blm.gov (accessed 2 july 2015). jūratė kamičaitytėvirbašienė professor kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research area landscape visual quality analysis, evaluation and regulation, methods of planned activity or object visual impact assessment, analysis of social preferences evaluating landscape visual quality and use of the analysis results in territory planning, evaluation of the potential of urban structures, expression of sustainable development conception in architecture, landscape architecture, town and territory planning address studentu st. 48, lt-51367 kaunas, lithuania tel. +37061477082 e-mail: jurate.kamicaityte@ktu.lt giedrė godienė doctor, freelanced landscape expert lithuanian geographical society, board member main research area landscape impact assessment, visual impact assessment, studies on landscape legislative system regarding the implementation of european landscape convention, methods and techniques of the public participation, involvement into decision making regarding the landscape issues address a. baranausko st. 8, lt-04224 vilnius, lithuania tel. +37068563451 e-mail: g.godiene@gmail.com gintas kavoliūnas lecturer vilnius college of design, department of photography main research area photographic apparatus and equipment, special technologies address kauno st. 34, lt-03202 vilnius, lithuania tel. +37068444076 e-mail: gintas@afd.lt about the authors 5 journal of sustainable architecture and civil engineering 2018/1/22 corresponding author: arne.riekstins@udem.edu digital prototyping and augmented reality models for studies of architectural design received 2018/07/16 accepted after revision 2018/09/05 journal of sustainable architecture and civil engineering vol. 1 / no. 22 / 2018 pp. 5-10 doi 10.5755/j01.sace.22.1.21255 © kaunas university of technology digital prototyping and augmented reality models for studies of architectural design jsace 1/22 http://dx.doi.org/10.5755/j01.sace.22.1.21255 arne riekstins university of monterrey, division of art, architecture and design (daad), av. ignacio morones prieto 4500 pte., 66238 san pedro garza garcía, nuevo leon, mexico the communication of an architectural design project by default is the selling point of any idea when it is being presented to the clients. the use of advanced digital prototyping and virtual 3d models can facilitate the process of presentation significantly, because these technologies allow understanding features that are hard or impossible to present in drawings or pure renderings. cad/cam paradigm has set new standards in the field of teaching architectural design, as the contemporary practice has raised the demands for standard skillset expected from future architects once they graduate and enter the design offices. digital systems that allow designing directly for manufacturing has returned the production and responsibility for giving engineering solutions back to architects. and parametricism in contemporary academic environment is one of the main driving forces of architecture that exercises the exploration of complexity, possible only through 3d modeling tools. therefore the use of technology in representing complex ideas becomes a standard procedure. the author explores the implementation of physical and virtual models in architectural design curriculum – cnc and rapid prototyping or pure virtual models in format of augmented reality experience. despite the time-intense learning curve of the additional specific tools and methods involved, there are more advantages to support the efforts of implementing new workflows in the studies of architectural design in as early stage as possible. students who mastered these skills were able to reach better understanding of tangible and more logical structures in the way they conceptualized, and demonstrated to have more advanced 3d thinking and independence on making formal decisions. both the physical and virtual models have their own strengths and weaknesses and neither one of them will totally eliminate the necessity of usage of each other. keywords: architectural design, augmented reality, cad/cam paradigm, prototyping. introduction studying architectural design always cover wide field of knowledge from concepts to executive building details. there are several ways of representing the final design in traditional methods – by architectural drawings (plans, facades and sections), renderings and scale models. the model making has been long time one of the most laborious tasks, as it implies to represent the design in full 3 dimensions, maintaining a certain scale aspect. the model making has been automatized with the advance of digital fabrication and prototyping, while the precision and new technologies have facilitated to reduce the time and costs associated to the process. new hybrid materials and developments in robotics have increased the possible scale of models, making the full 1:1 scale prototyping viable for making larger building components for later assembly or printing an entire house in 3d directly from design files, as it is manifested by cad/cam paradigm – to bring comjournal of sustainable architecture and civil engineering 2018/1/22 6 methods puter aided design straight to computer aided manufacturing. because technology develops it continuously gives architects new possibilities and sets new challenges. one of the pioneering augmented reality (ar) applications were discussed more than 20 years ago by starner et al. (1997), stating that wearable computing is moving computation from desktop to the user, while a new community of networked, wearable-computer users can explore seamless interaction between the virtual and physical environments. last decade has finally brought to the masses great hand-held devices in form of smartphones and tablets with good quality displays and cameras that can represent models in a more interactive virtual way through the ar tools that can significantly reduce the costs on model making and in several cases even replace physical models as a paradigm. nevertheless there are certain advantages and disadvantages of this new ar technology that will be discussed further in this article through several applications in various architectural design-related academic studios. to compare and analyze the application of physical vs. ar models author integrated them in two different architectural design studio setups, one method per semester at university of monterrey in mexico. the application of digital prototyping was carried out in a studio of integral architectural design taught at 4th study year of undergraduate architecture program where the task involved designing kindergarten, church or an art-café. during the entire 16-week semester there were two different physical prototype assignments – to make a structural detail model and to make a 3d printed scale model of the entire volume to complement the final project presentation. the application of ar was integrated in a studio of architectural interior design taught at 5th study year, where during the semester students were making three different small projects and to present them – each project had a virtual model instead of a physical model. these two studio setups allowed comparing the features and pointing out several strengths and weaknesses of physical vs. ar models. in the communication of design ideas from architects to engineers and builders the usual format of traditional architectural drawings are mostly limited to two-dimensional sketches. while that is more than enough in a construction environment to understand and build the project, there are plenty of situations where an actual three-dimensional scale model is needed – presenting it to clients, investors, society, exhibiting etc. and the presentation of the model can also be virtual and in a form of an ar application. model making distinguishes two fundamentally different techniques where the material is either cut out or 3d printed by adding the material layer by layer. in architectural design schools internationally both of the computerized methods are being used extensively and it is definitely replacing the manual model making by the usage of hand tools. small laser cutters and desk size 3d printers do the job in an excellent quality and the fabrication costs have become very accessible in the last two decades. usually the architectural prototypes are being made in 1:500 scale for urban or landscaping projects, in 1:200 and 1:100 scale for building architecture and in 1:50 for interior architecture or smaller projects like mini houses that can show lots of detail. further the 1:25, 1:20, 1:10 and 1:5 scale is more used to represent detail models of specific parts or structural components. full 1:1 prototyping in academic use is more rarely executed, as increasing up to full scale has much more material and structural engineering challenges to model making, so very often the 1:1 scale is being obtained by subdividing the object into smaller elements or assembly components, that are being assembled at the final stage. as for the academic research, these projects usually are small pavilions or temporary installations made of less time-resistant materials like mdf, triply, wood, all sorts of plastics and light metals. prototyping in 1:1 scale has become reality due to advent of recent robotic technologies that extend the abilities of common computer numeric control (cnc) machinery meanwhile providing more effectiveness in the fabrication speed and complexity. the robots set new boundaries of research and act as an accelerator for creativity of the design processes. automation of design and manufacturing 7 journal of sustainable architecture and civil engineering 2018/1/22 methods allows constant development of new shapes and forms that can be inheriting the latest know-how of sustainability and thus reach the highest economy of material usage or even support a total zero waste fabrication. the most feasible increase of scale in fabrication has brought us to reach the full 1:1 architectural scale by using ultra-high performance concrete in large-scale 3d printers that work with an additive manufacturing (am) technique. year 2017 brought to us world’s first 3d printed concrete bridge for the cyclists in the town of gemert in netherlands. work on printing the bridge, which has some 800 layers, took about three months and it is made of reinforced, pre-stressed concrete, according to the eindhoven university of technology (tg 2017). several full-scale houses have been 3d printed as well – in 2016 in beijing’s tongzhou district (wheatstone 2016), 2018 in austin, texas (badalge 2018) and in nantes, france (drury 2018). original first prototypes of ar applications were big mobile wearable devices, where the user would basically carry around a backpack with the whole setup that includes a notebook computer, variety of sensors and peripheral devices, while the graphical augmentations were usually shown through an optical see-through head-mounted display (wagner et al. 2005). with such limitations as the heavy weight, comfortable wearability or looking inadequate in terms of social context, these setups were more appropriate for a laboratory level applications. further on ar has found its use in all sorts of simulations, including industrial use, info systems, navigation and the world of entertainment through immersive games. currently ar models are relatively easy to create out of an existing 3d modeled project in sketch up, rhinoceros, 3ds max, autodesk maya and many other software. typically the model is being exported to an obj extension format (3d object) file with an additional mtl extension file (materials and textures library), further it is uploaded straight to the mobile device or uploaded online to a secondary processing program that makes the model available through its own native application. to visualize the model in ar it is enough to point the mobile devices camera to an empty surface or special marker and it appears in the given space. the benefit of a specific location based marker is that the model can be handled similarly to a physical model – you can hold the marker in one hand and handle it as a physical model rotating it around and seeing it from closer or further distance. in the academic application ar player and augment apps showed the best compatibility and were chosen because of great functionality and easy learning curve to use them. first physical model application was carried out in a studio of integral architectural design to address the structural details of geometrically advanced architectural objects. the 3d modeling software applied in the studio was autodesk maya or rhinoceros, both of them being very powerful tools for freeform and non-orthogonal designs to be explored. the freedom of shape and form was a precondition to designing unique constructive and structural details that at the 2nd midterm had to be presented in scale models of 1:20 up to 1:5 scales. to understand the logics of conceptual vs. real building situation, all of the studio models had to be made using a 2-dimensional cutting method of flat or paneled wooden or mdf materials. this involved unrolling any 3d rotated pieces down flat for the cutting layouts, and any irregular geometry had to be proliferated to be composed of 2d planar elements only. the actual model size was limited to a base of 40x40 cm. some authors were concentrating in revealing the structural details that connect slab to the facades (see fig. 1) while others studied the exoskeleton shells and their ribbed connections (see fig. 2). in almost all of the cases this exercise helped finding more optimal constructive solutions and elements that needed to be improved. the second physical scale model was already at the end of the semester to present the entire project in the final presentation. precondition for these models were to use high-resolution industrial level 3d printers available at the laboratory of digital fabrication at university of monterrey. after few small 3d print tests and the given 3d printer accuracy to render the models in 0.1 mm precision, it was decided that every model shall be made in 1:200 scale where most small journal of sustainable architecture and civil engineering 2018/1/22 8 parts like window frames, stairs and even some small wall surface articulation could be reproduced. industrial level 3d printers like the stratasys uprint can print from the actual model material that is very tough abs-plastic and it can print an organic material that afterwards is being removed for supporting elements that have no base and that are floating in the air. to save the filling support material usage in the inside of the model volume for roof structures, those elements were printed separately thus allowing the models to be opened revealing their full architectural interiors. from the two applications of model making in a design studio it was clear that any model making involves additional time, either for preparation of the model files for fabrication or actual assembly of the parts. the need of the models can be eliminated totally but that is an ongoing research as it depends from many factors like the reason for making model as a paradigm. simplest and most straightforward method to save precious designing time and concentrate more on details is making virtual ar models. the method will probably never substitute physical scale models but it is widely applicable to short term projects and projects where many modifications need to be checked in almost real time. author decided to check its potential applying ar model strategies in an interior design studio where the semester was divided into three distinct projects, each being made from scratch in 4-5 weeks time. as there is a very short learning curve to obtain a usable virtual representation of already existing 3d model, it was mainly small restrictions that needed special attention. for example, a 3d object contains too many polygons and therefore is too heavy for exporting or processing and various problems occurred with custom made textures that again reached the limits of being big file sizes that would take forever to post-process. in most cases the models were readily available for viewing on a handheld device just minutes after its upload and online processing (see fig. 5). fig. 1 structural detail model in 1:10 scale laser-cut and assembled of parts from plywood and balsa wood fig. 2 structural detail model in 1:20 scale laser-cut from 5mm mdf material fig. 3 scale model of a church project in 1:200 with removable roof to reveal its interior architecture made of abs-plastics on a stratasys uprint industrial level 3d printer fig. 4 scale model of a kindergarten project in 1:200 made of absplastics on a stratasys uprint industrial level 3d printer fig. 5 augmented reality model of a juice bar interior project on an iphone 6 running augment application 9 journal of sustainable architecture and civil engineering 2018/1/22 ar models do have additional features that physical models do not have and in reverse. the full comparison that is based on authors experience in two different studio setups is shown in table 1, comparing all aspects from spatial representation qualities to related expenses. the biggest risk is having an incomplete design strategy or having file errors, including wrongly modelled geometries. especially 3d printing is less forgiving for errors like geometries not being closed solids or solids having inside-out orientation of their surface normals – the vectors which are perpendicularly oriented to its tangent plane of its surface, by default facing outwards. another issue is the extra time needed for modeling to prepare files for physical 3d model fabrication. often by reducing the scale there are elements that cannot be simply scaled down or need to be simplified in order to represent them well. there are also many limitations of the complex geometries to be made into physical models, this being one of the deciding factors for choosing model making strategy of an assembled model from various laser-cut parts or performing a full 3d print. the industry of architecture in the future application of any model making is still very open for a continuous research of what is the very best way to get models done. new technologies are being made available in increasing speeds and therefore the experimentations in both physical and discussion table 1 features comparison of physical vs. augmented reality models feature physical scale models augmented reality models spatial sensation great sense of volume or detail in its complete volume virtual immersion to fully explore the outside or inside of a model materiality limited to chosen model material and color full color, textures and lighting with shadows detail level details reduced to the resolution of the chosen scale and fabrication method very accurate details in any scale kinetics fixed model of one definite state allows animation and movements of elements (for ex., shades open/closed) sense of scale one chosen scale full 1:1 scale, additional zooming or magnification feature has a slight risk of loosing sense of scale handling handheld, fixed to a stand or boxed fixed to a marker or space that gives mixed sensation of its actual physical handling creation time from several hours to days, depending on fabrication method and parts to be assembled few minutes (conversion, exporting and uploading to mobile devices) speed of accessibility of the model physical model can be seen immediately when it is reached by the viewer ar model often involves downloading and installing a specific application or loading the model from a web browser (limitation is the data speed and availability of internet) mobility the size and weight are constraints to face when transporting physical models, also they can only be exhibited in one location only via e-mail or a download, can be copied and seen simultaneously virtually anywhere where the internet reaches or where you can carry it as a previously downloaded file and see it in a compact mobile device updating model usually involves making new model or parts of a model very flexible – any momentary design changes can be updated during the workflow related expenses material, fabrication and assembly labor totals depending on the size and complexity model cost very low, additionally the value of the hand-held device journal of sustainable architecture and civil engineering 2018/1/22 10 virtual models need to be made in academic environments first, followed by application in design offices. to be prepared for the real life modeling situations future architects must have accumulated the expertise that makes presenting their design ideas as clear as possible. conclusions after a more in-depth analysis of physical vs. ar models we can conclude that neither of the two methods does completely eliminate each other of the modeling methods, and in a perfect real-life application they rather can complement to showcase the best elements of any design from a broader point of view. there will always be intentions to replace or improve the given technologies and if possible also speed up the model assembly or processing times, cutting down the expenses and the material usage. future profession of architects will still have to use any of the modeling techniques analysed in this article, cleverly choosing the best way to represent their projects to the clients. therefore it is very important to integrate the prototyping and all possible virtual representation methods in the academic study projects so they can be learned in making actual designs. it has to be noted that any model making involves lot of time in specific 3d software and significant efforts in fine-tuning or detailing. prof. dr. marcelo espinosa from university of monterrey (udem), mexico for sharing immense amount of details and attitude to the technical details in design and javier gomez flores, technician of prototyping and digital fabrication laboratory at center of roberto garza sada of art, architecture and design also from udem, for countless hours of help in mastering the industry leading prototyping machinery. acknowledgment badalge k. in world‘s first 3-d printed home community, houses will be built in a day for $4000. archdaily, 27 mar. 2018, https://www.archdaily. com/891065/in-worlds-first-3d-printed-community-houses-cost-4000-dollars-and-are-built-in-24hours. drury c. world‘s first 3d-printed home unveiled in france. independent, 11 apr. 2018, https://www.independent.co.uk/news/world/europe/3d-printedhome-world-first-france-a8298446.html. starner t., mann s., rhodes b., levine j., healey j., kirsch d., picard r.w., pentland a. augmented reality through wearable computing. presence: teleoperators and virtual environments, 1997, 6(4): 386-398. https://doi.org/10.1162/pres.1997.6.4.386 references wagner d., pintaric t., ledermann f., schmalstieg d. towards massively multi-user augmented reality on handheld devices. in: gellersen h.w., want r., schmidt a. (eds) pervasive computing. pervasive 2005. lecture notes in computer science 3468. berlin, heidelberg: springer; 2005. wheatstone r. world‘s first 3d printed house is completed after just 45 days in revolution for home building. mirror, 27 jun. 2016, https://www.mirror. co.uk/news/world-news/worlds-first-3d-printedhouse-8297190. world‘s first 3d-printed bridge opens to cyclists in netherlands. the guardian, 18 oct. 2017, www. theguardian.com/technology/2017/oct/18/worldfirst-3d-printed-bridge-cyclists-netherlands. dr. arne riekstins full professor of architecture university of monterrey, department of art, architecture and design (daad) main research area digital and parametric architecture address av. ignacio morones prieto 4500 pte 66238 san pedro garza garcía nuevo leon, mexico tel. +52(81)8215-1450 e-mail: arne.riekstins@udem.edu about the author 27 journal of sustainable architecture and civil engineering 2018/1/22 *corresponding author: aniebietabasi.ackley1@myport.ac.uk factors affecting the shortage and or provision of sustainable affordable housing in developing countries – a case-study of cross river state, nigeria received 2018/04/23 accepted after revision 2018/07/05 journal of sustainable architecture and civil engineering vol. 1 / no. 22 / 2018 pp. 27-38 doi 10.5755/j01.sace.22.1.20573 © kaunas university of technology factors affecting the shortage and or provision of sustainable affordable housing in developing countries – a casestudy of cross river state, nigeria jsace 1/22 http://dx.doi.org/10.5755/j01.sace.22.1.20573 aniebietabasi ackley*, catherine teeling portsmouth school of architecture, university of portsmouth, united kingdom eugene atamewan department of architecture, cross river university of technology, calabar, nigeria the problem of shelter in developing countries is the shortage of affordable housing especially for the urban poor. this housing shortage exposes the citizens to live in inadequate housing conditions. this study presents evidence of the factors affecting the shortage and or provision of sustainable affordable housing in cross river state, nigeria. primary data was collected from semi-structured interviews and unobtrusive observations. this data was then analysed using descriptive statistics (frequency counts and simple percentages). the study findings revealed that, many interviewees suggested that rural-urban migration 98% (n=48), and lack of planning, maintenance and management 90% (n=45) as the main factors leading to the shortage of affordable housing. the interviewees suggested that poor implementation of government housing policies 84% (n=42), difficulty in purchasing land 94% (n=47), the high cost of building materials 96% (n=48), and lack of finance and access to credit facilities 80% (n=40) were significant challenges hindering the provision of sustainable affordable housing. the study concludes that affordable housing shortage and or provision can be minimised and enhanced by encouraging building developments that are; flexible and smart with minimal usage of non-renewable energy, use of durable and locally available building materials that respond appropriately to environmental factors and forces, availability of housing for the target population and a switch to a more sustainable way of planning, design, construction and maintenance of buildings. keywords: sustainable, affordable housing, cross river state, nigeria. the un habitat agenda, (2005) describes affordable housing as an important component to establish sustainable development for both society and the economy. it states that a functioning housing sector that offers appropriate affordable housing along with a sustainable pattern of urbanisation is critical for the future of any country. housing is a fundamental necessity for every human being, irrespective of financial standing. american psychologist, abraham maslow ranked shelter as second only to food in his hierarchy of human needs and this is generally accepted. despite the importance of housing to the socio economic development of man and society as a whole, housing problems have remained endemic throughout the world (otubu, 2012). the term ‘housing conditions’ is defined as the total state of the physical environment and the introduction journal of sustainable architecture and civil engineering 2018/1/22 28 satisfaction level of a particular dwelling unit measured against variables that makes it liveable at a particular time (omole, 2001). the variables relating to housing conditions include safety, security, structural stability, environmental quality, light, heating, ventilation; as well as basic infrastructure services such as water, sanitation and waste disposal facilities (un-habitat, 2005). the sustained quality of better housing conditions in any area is a function of the characteristics of the various materials that make up the building, the spatial quality, response to site conditions and other socio-economic factors that affect the environment (un-habitat, 2005; akpan-idiok & ackley, 2017). the provision of affordable housing has always been a significant problem in nigeria that requires addressing. mundra and sharma, (2014) suggested that, millions of people especially the low-income earners are still living in inadequate housing in many countries most particularly in developing countries. cross river state today is such an example, it has a significant lack of and problem of affordable housing provision for its ever increasing (urban) population/citizenry (ewa, offiong, njar, & ita, 2013). the increase in urban population have made housing difficulties more serious for lower income groups and the problem has been complicated by inflated real estate values, speculative activity, unemployment, low earning capacity and lack of maintenance and planning (otubu, 2012). the housing problems in cross river state have led to social, cultural, psychological, and environmental problems for the citizens. it has resulted in low standards of living, and the growth of slum neighbourhoods that have become common features of the state’s urban areas (ewa, et al, 2013). therefore, the challenges affecting the shortage and the provision of affordable housing relies on addressing issues specific to many of the slum settlements. literature review housing situation and overview of housing schemes in nigeria the housing situation in nigeria has been affected by the increase of significant rural-urban drift. this has been influenced (or caused) by the lack of development of the rural areas, the government bias in the choice of location for urban public infrastructure, and the poor economic conditions of the rural dwellers (olotuah & ajenifujah, 2009). a brief review of past housing policies and programmes in nigeria highlights the different periods of official intervention in housing delivery. these include; the colonial period, post-independence period, post second republic periods and the current housing programmes. the colonial period (19281960) the national housing policy (nhp, 1991) states that, due to the bubonic plague epidemic between 19281929 the then government of the defunct lagos colony brought into existence by law the lagos executive development board (ledb), which was charged with the responsibility of planning the development of the capital city of lagos. this led to the production of a masterplan for the layout of ebute metta area of lagos. this housing scheme was developed specifically to house civil servants and was executed through a payroll deduction system. in 1955, during the preparation for independence, the concern for slum conditions became paramount and subsequently brought the central lagos slum clearance scheme into effect. the scheme opened up apapa and later victoria island as high and low-density developments within lagos state. additionally, slum clearance programme enabled the construction of additional houses in suruiere area of lagos state, this was the first attempt in urban renewal in nigeria (nhp, 1991). the aim of the slum clearance scheme was partly designed to provide temporary residential housing for displaced people from the slum areas of central lagos, providing the re-allocation of redeveloped land in central lagos, this however became permanent housing for the previous 29 journal of sustainable architecture and civil engineering 2018/1/22 slum dwellers. the actions by the lagos executive development board (l.e.d.b.) produced many solutions such as; the eric moore and akinsemoyin housing estate, surulere, phase ii of the workers housing estate and surulere, lupe and isolo estates among others (jiboye,2011). in 1958, the western regional government pioneered the establishment of housing corporations, which was replicated by other regions of nigeria. the main function of the housing corporations was the construction of housing units for sale to members of the public, this was achieved through the provision of loans to whoever wished to build their own house on their land (jiboye, 2011). most of these estates are currently deteriorating due to lack of maintenance and management. post-independence period (1960-1983) during this period many initiatives were established in the eastern, western and northern regions that explored the potential of housing corporations, followed by a national council of housing that enabled mortgage repayment schemes. this scheme allowed people to borrow money to build houses that could be repaid over many years. the schemes failed because they only focused on developments in capital cities, which were left to deteriorate. with public production of shelter as a priority, the period of 1971-1980 had a significant level of increase in the supply of housing due to government participation. this were because of the interest and involvement of the public sector in shelter delivery and its importance within the overall economy. with the establishment of the federal housing authority (fha) in 1976, the national housing programme was launched. this program provided affordable housing to nigerian citizens on longterm mortgage repayment terms and it is viewed as the first significant effort of the nigerian government to provide affordable housing in nigeria. it led to the development of festival town and lpaja town in lagos, the amuwo odofin phase 1 estate in lagos and the first ever federal lowcost housing estates in a further 11 state capitals of nigeria. fha was established under decree no. 40 of 1973 and amended by cap 136 lfn of 1990. in 1979, the nigerian government embarked upon low cost housing development in all of the 19 states of the country, the government allocated n1.9 billion for housing construction, in all the twenty states of nigeria, including abuja. by june 1983, n600 million (37.5%) had been spent to complete only 32,000 units, yielding an overall achievement level of just 20 per cent (jiboye, 2011). this period witnessed the continued increasing deficit on urban housing as well as its continuous deterioration in the rural areas. post second republic periods (1984 to 1999) during this period, nigeria was faced with the challenges of having many suspended/abandoned housing projects due to the failure of previous housing programmes. thus, the completion of the abandoned housing stock became the focus of the government (thisdayonline, 2009). to complement the above, the government in 1994-1995 launched the national housing programme designed to provide about 121, 000 housing units to all income groups in nigeria (lanrewaju, 2013). the program was focused on establishing a permanent housing delivery system that will not be solely reliant on the government treasury, but rather self-sustaining and enduring (lanrewaju, 2013). due to inadequate funding, planning and conception, poor implementation, lack of public confidence, problems of access to the national housing fund, under-pricing, costing and inflation this programme failed (thisdayonline, 2009). current housing delivery scheme 2000till date in 2003, the federal government established the federal ministry of housing and urban development (fmhud), and proposed a housing reform. there was an illusion that houses were available. mabogunje (2004) suggested that other legislative requirements must be amended substantially to bring their provisions in line with the new housing regime. this policy placed the private journal of sustainable architecture and civil engineering 2018/1/22 30 sector in a focal position for the delivery of sustainable affordable houses. the ministry of housing also reviewed and amended the land use act to ensure efficient access and facilitated land registration process, along with a new mortgage regime to accelerate more favourable mortgage terms (thisdayonline, 2009). the new national housing policy came into publication in january 2004. the framework for its operation involved restructuring of existing structures and new laws. within this, a new federal ministry of works and housing was created from which a new national housing policy emerged, ensuring the construction of one million houses annually to boost infrastructural development (oyekachi, 2014). this social housing policy adopted a position where every citizen ‘counts’ in the provision of affordable housing. in august 2014, the nigerian government launched the first 10,000 affordable housing mortgage scheme under the nigerian housing finance programme, in an effort to help bridge the housing deficit in the country. studies show that the national housing deficit from1991 increased from 7million into an estimate of 12 15 million units in 2008 and over 16million in 2013. this represents housing for about 130-140million people, of which more than 65% represents the low and medium income groups of nigeria population. this signifies about 85% of the housing demand for the nation (oyekachi, 2014). this increase illustrates the inadequacies of the policies that have been adopted over the years and that the housing developments are not within the reach of the low and medium income groups. hence, many scholars (omole, 2001, diogu, 2004, jiboye, 2011, otubu, 2012, lanrewaju, 2013 and oyekachi, 2014). have identified; unsuccessful government programmes which lacked continuity with changes of government, inadequate funding of most of the projects, corruption, lack of planning, maintenance and management of housing projects, poor design and implementation as reasons for the failure of many housing schemes in nigeria: these illustrate the difficulties and drawbacks for any possible recommendations that will enhance the provision of affordable housing in nigeria. in proffering recommendations to tackle nigeria’s housing problems, oyekachi (2014) suggested that, a housing policy which facilitates self-help ownership at an affordable price is the best policy option that nigeria should adopt and that, nigeria’s housing finance system needs reinforcement to enable the urban and rural citizen’s easy access to credit facilities. study location the study investigated two residential housing developments in cross river state. the first is the federal housing estate development (fhe), calabar built in the 1980s. it was selected for analysis because it formed part of the nigerian national housing policy prototype building programme for low income earners. the second housing development is crospil housing estate located at akpabuyo local government area (lga) of cross river state. it is an on-going housing development built by the cross-river state government with the first of its phases completed in 2010. both developments are located in latitude 4.9º north and longitude 8.32º east in the coastal materials and methods fig. 1 fhe calabar: source: authors’ field work, 2015 31 journal of sustainable architecture and civil engineering 2018/1/22 south-eastern part of nigeria with a distance of 13km apart and 12m height above sea level. calabar and akpabuyo are in the tropical rain forest of nigeria; the mean temperature is about 25°c, the annual rainfall exceeds 300 millimetres, and the relative humidity is high throughout the year (akpan-idiok, 2012). study population data was collected from fifty tenants overall. this housing was designed for government employees. thirty tenants were interviewed in calabar and 20 were interviewed at akpabuyo. sample and sampling technique fifty housing units were randomly selected for the interviews, using a systematic sampling technique of about 10% of total units in each housing estate. the interviews were conducted over a period of three weeks in early 2015. the number for the selection was based on the time limitations. calabar fhe has around 300 housing units which include, two and three-bedroom two storey buildings, two and three-bedroom bungalows as well as one-bedroom bungalows. most of the buildings in the estate have recently been demolished due to the un-repairable state of the buildings and new private structures are currently being erected. akpabuyo crospil estate has 200 housing units consisting of 64 three bedrooms detached two storey dwellings and 98 three-bedroom semi-detached bungalows; 26 two-bedroom semi-detached bungalows as well as 12 units of one-bedroom two storey terraced housing. fig. 2 crospil housing estate, akpabuyo: source: authors’ field work, 2015 table 1 housing samples for interview: source: authors’ field work, 2015 location total number of house types number of estates selected total number of housing units in the estates no of selected housing units/households (10% of total) interviews undertaken calabar 3 1 300 30 30 akpabuyo 4 1 200 20 20 ethical considerations a letter of introduction and permission was taken to the community leaders in order to gain access to carry out the study. verbal consent was also obtained from the interviewees before the study commenced. instrument for data collection data for this research was obtained through a semi structured face to face interview. this method allowed each interviewee to express their perspective of how their houses function as well as the problems with the form of affordable housing and their environment. the unobtrusive observation method was also journal of sustainable architecture and civil engineering 2018/1/22 32 used to gather data. this allowed the authors to record the respondent’s behaviour within the houses with specific end goals to assess how the house was used and quality of the living conditions. this method was used because the authors were familiar with the environment of both case studies, the form and mode of construction of the houses, attitude and manners which the people exhibit, and the ways the individuals viewed things. the data obtained were analysed using descriptive statistics such as percentages. results the socio-demographic data of interviewee (n=50) fifty interviewees participated in the study, many of the interviewees were females 80% (n=40) and married 70% (n=35), 80% (n=40) were christians and 60% (n-30) between the ages of 35 to 49 table 2 socio-demographic data of interviewee: source: authors’ field work, 2015 s/n item num percentage (%) 1. sex male 10 20 female 40 80 2. age 20-34 3 6 35-49 30 60 50-64 15 30 65 and above 2 4 3. religion christianity 40 80 islam 1 2 eckist 5 10 others 4 8 4. marital status single 1 2 married 35 70 divorced 9 18 widow 4 8 widower 1 2 5. occupation farmer 1 2 house wife 3 6 trader 6 12 civil servant 40 80 6. level of monthly income n20,000 n39,000 5 10 n40,000 n59,000 10 20 n60,000 n89,000 30 60 n90,000 and above 5 10 7. nationality nigerian 50 100 foreigner 0 0 50 100 33 journal of sustainable architecture and civil engineering 2018/1/22 years. majority of interviewees were civil servants 80% (n=40) with 60% (n=30) having an average monthly minimum income of n60, 000 naira (£250), and all were nigerians, 100% (n=50). all interviewees were permanent residents with majority having at least more than two years’ occupancy within their apartments and houses. fig. 3 interviewees length of occupancy: source: author’s field work, 2015 factors affecting the shortage and provision of affordable housing in cross river state as shown in table 3 below, high rural-urban migration, 96% (n=48), high cost of building materials 96% (n=48), difficulty in purchasing a land 90% (n=45), poor maintenance of existing buildings 90% (n=45), and poor implementation of government policies 42% (n=84) are key among the various table 3 factors affecting the shortage and provision of affordable housing: source: author’s field work, 2015 factors n-50 % high rate of rural-urban migration 48 96 poor planning and maintenance of existing buildings 45 90 poverty (inadequate finance) 40 80 use of inferior building materials 43 86 poor basic infrastructure provision by government 34 68 poor implementation of government housing policies 42 84 high cost of rent 37 74 destruction of facilities by occupants 30 60 poor design and implementation 39 78 environmental problems (pollution, flooding, topography) 40 80 difficulty in purchasing land for building 47 94 high cost of building materials 48 96 difficulty to access credit facilities 40 80 high cost of maintenance 38 76 high risk of fire incidents 26 52 high cost of labour to build 35 70 abandoned government housing projects 35 70 journal of sustainable architecture and civil engineering 2018/1/22 34 factors affecting the shortage and provision of affordable housing. the table below presents a list drawn up from the responses to the interview and questions. when interviewees were asked if their house is suitable for their status, 90% (n=45) of interviewee said no, because of most of the factors stated above. when interviewees where asked of what improvements they would recommend for the provision of affordable housing, a large majority of interviewees recommended a positive improvement to the different challenges mentioned in table 3 above, such as: provision of basic amenities (light and water, etc); the use of good building materials that have longevity; and access to credit facilities to assist the building of their houses with a low or possibly no interest rate. it is evident from the study that, majority of interviewees identified high rural-urban migration as a major factor contributing to the shortage of affordable housing in cross river state. high population growth drifts constantly to urban areas, with corresponding inadequate measures for the provision of affordable housing for the populace gives rise to slum and squatter housing; an offshoot of overcrowding which results in high building density and high occupancy rate. the large population of people in the urban cities of cross river state is a challenge to the accessibility of affordable housing in its urban cities. the statistic in fig. 1, 2 and 3 below showed the progressive increase in the population of nigeria up to 2015. the bar chart above shows the changes in population as a result of people migrating into the urban cities of nigeria. migration is said to occur both on a short term or long-term basis depending on the conditions in which people find themselves in. as a result, the proportion of the nigerian population living in urban centres has increased phenomenally over the years. over 50% of nigerians as indicated in the chart above now live in urban centres. this has created severe housing problems, resulting in overcrowding, shortage of housing and a situation in which about 60% of nigerians can be said to be ‘houseless persons’. majority of interviewees acknowledged that, poor planning and maintenance of existing buildings contributes significantly to the shortage of affordable housing. for a structure to remain durable, it is important that there is a good maintenance policy in place. where buildings are not maintained and they have been allowed to deplete for a very long time, the rehabilitation and renovation becomes costly, capital intensive and sometimes properties are abandoned rendering them unusable and depleting the existing housing stock. similarly, it was observed that most occupants also destroy their houses and associated facilities to a condition where they become inhabitable discussion fig. 2 nigeria’s population statistics: source: worldometers.info, 2015 35 journal of sustainable architecture and civil engineering 2018/1/22 fig. 3 population changes in nigerian urban areas: source: worldometers. info, 2015 fig. 4 percentage changes in nigerian urban areas: source: worldometers. info, 2015 and are eventually abandoned. in some cases, houses are subject to high risk of fire incidents in nigeria, thus houses are engulfed by fire and left abandoned. these buildings are not rehabilitated either by individuals or the government and over a long period of time the properties completely deteriorates decay and are destroyed. the use of inferior building materials was identified by 86% of interviewees as a factor resulting in the shortage of affordable housing. buildings rapidly decay because of the use of poor quality (inferior) building materials in the construction, this largely impacts on the life expectancy of the existing housing stock and the long-term durability of the buildings. this depletes existing housing within a few years, thereby not meeting any aim towards sustainability, and clearly not addressing the needs of the present generation as well as that of future generations. furthermore, high rental costs were identified as another significant factor with many interviewees commenting that, people living in government low cost housing estates are mostly middle-income earners. this because government housing programmes in terms of building design do not respond to the journal of sustainable architecture and civil engineering 2018/1/22 36 target of the low-income population in the long term, and has resulted in middle and high-income earners who have the finances to highjack the completed developments. when asked the challenges of providing affordable housing by building their own houses; interviewees identified difficulty in purchasing land to build, lack of finance, access to credit facilities, lack of insurance policies to share risk, high cost of labour to build and high cost of building materials as a major drawback to providing, building and owning a house. the nigerian land use act of 1978 vests all land in the government making this an obstacle to land available for housing development. unfortunately, in nigeria there is no mechanism for risk sharing and insurance policies that will encourage banks and other financial institutions to extend mortgage loans to people at the lower income level. nigerian financial institutions settle for lending to the rich. there is also absence of a national credit database that can provide credit information of all individuals that enjoy financial services in any form. with the nigerian building industry largely dependent on imported foreign building materials and considering the current economic crises of the country resulting in high exchange rates; there is a drastic rise in the cost of building materials. these factors have significantly hindered the provision of affordable housing. about 80% of interviewee said that the government is responsible for the challenges facing the provision and shortage of affordable housing. inadequate provision of basic infrastructure by government, corruption, poor implementation of housing polices and economic meltdown were identified as key reasons why government should be held responsible. it is worthy to mention that, over the years, the nigerian and cross river state government have enacted various housing policies and programmes aimed at providing affordable housing. these programmes have been unsuccessful because of corruption; a situation where contractors divert and embezzle money meant to execute a project and leave it abandoned. most housing programmes lacked continuity with changes of government, and inadequate funding of most of the projects have all led to the shortage and or provision of affordable housing. the interviewee recommended the provision of basic infrastructure, and the use of sustainable local building materials as the improvements they will appreciate in providing affordable housing. this study recommends that, to provide affordable housing in cross river state, cheaper, durable and locally available building materials should be encouraged. this will help to reduce cost of construction which is advantageous for the provision of low cost housing. the use of environmentally degradable construction materials such as earth, thatch and turf and the application of traditional and vernacular methods which are in accordance with the traditional use of these materials. the “mud” walls of traditional buildings are similar to earth walls and adobe walls, which are enjoying as acclaim in the current trend of sustainable architecture. when used well, the clay can be aesthetically pleasing as part of a building edifice. high technology solutions such as the use of modern technology and materials that protects and conserves energy, recycling of waste materials in buildings and the production of intelligent buildings that respond appropriately to environmental factors and forces should also be encouraged. they should be a procedure of monitoring housing schemes by the government involving all stakeholders within the community and the building industry. integration of community engagement and participation in the development of the designs and their implementation to ensure that they meet the housing needs of the target population. to make a significant improvement in the provision of affordable houses, there is need for an enabling land use policy/law. laws making it mandatory that houses built for the low-income group should be occupied strictly by that group. careful policy formulation and planning in terms of the character, structure, location of the neighbourhood for affordable housing is required to ensure the appropriate performance of the corporate estate developer. government should provide basic infrastructure in different areas and regions and create employment to discourage rural-urban migration. government should 37 journal of sustainable architecture and civil engineering 2018/1/22 enact and enforce policies that should do with maintaining high sanitary conditions, management of existing housing facilities and its maintenance. this should be something that must be actively maintained and at times restored. housing construction should be monitored to ensure the use of standard building materials and techniques. the use of renewable energy strategies (solar panels, wind turbines, wave and tidal power) to resolve the issues of power shortage is a sustainable strategy for the provision of a sustainable affordable housing. architects and planners should be encouraged to provide eco-friendlier designs integrating every sector of living, including the implementation of smart growth initiatives thereby providing a frame work for future development. moreso, the citizens should be educated on loan facilities and public-private partnership in development should be encouraged. finally, adequate planning should be done by the planning authorities in cross river state to provide a mechanism to balance environmental and economic factors, by providing a framework to integrate diverse natural resources and growth management activities in a holistic ecosystem-based approach. this study has identified various factors affecting the shortage and or the provision of affordable housing in cross river state. for sustainability of affordable housing delivery, the changing needs of users must be considered to design houses for the target population which meets the income level without compromising the standards of a good housing condition. to encourage sustainable affordable housing in cross river state is a difficult challenge, the existing basic amenities and infrastructure problems are a key concern. it is important for future developments in cross river state to adopt a more sustainable mode of planning, design, construction and maintenance of its buildings by providing housing types that promotes the culture, lifestyle of the people and the use of locally available building materials in its construction. conclusion akpan-idiok, a. physiochemical properties, degradation rate and vulnerability potential of soils forme. international journal of agricultural research, 2012, 358-366. akpan-idiok, p., & ackley, a. sustainable therapeutic environment; impacts of the indoor environment on users ‘ perception of wellbeing in public healthcare facilities in calabar municipality, nigeria. world journal of pharmaceutical and medical research, 2017, 3(6), 27–37. diogu, j. the architecture of low-income housing: evolving the micro -residential system. journal of the association of architectural educators in nigeria, 2004, vol. 3 no.2. ewa, e., offiong, v., njar, g. n., & ita, a. e. assessment of housing affordability problem in calabar metropolis, cross river state, nigeria. journal of humanities and social science, 2013, 16, 23-29. federal republic of nigeria. draft of national urban development policy. abuja: federal ministry of works and housing, nigeria, 2004. jiboye david. urbanization challenges and housing delivery in nigeria: the need for an effective policy frame work for sustainable development. internareferences tional review of social sciences and humanity, 2011, 176-185. lanrewaju f. a. housing delivery in nigeria: repackaging for sustainable. nternational journal of african and asian studies, 2013. mabogunje, a. urbanization in nigeria. london: university of london press, 1968. mundra, k and sharma, a. housing adequacy gap for minorities and immigrants in the u.s. american housing survey, the institute for the study of labour (iza), 2012, n0. 80, 38. olotuah, a. neighborhood quality in residential estates: an analytical appraisal of two estates in akure, nigeria. international journal of environmental science, 2005, 99-105. otubu, t. the missing link in housing sector reforms in nigeria. acta universitatis danubius, 2012 vol. 4, no. 1. omole, f. basic issues in housing development. ondo: femo bless publications, 2001. oyekachi, a. effects of governance and policy reforms on affordable housing in nigeria. international journal of innovation and scientific research, 2014, 413-419. journal of sustainable architecture and civil engineering 2018/1/22 38 un-habitat. cities without slumns. sub-regional program for eastern and southern africa. nairobi, kenya: un-habitat, 2005. worldometers.info. retrieved from elaboration of data by united nations. world population prospects: population of nigeria: www.worldometer.info/ world-population/nigeria-population, 2015. aniebietabasi ackley phd researcher faculty of architecture and design, school of architecture, victoria university of wellington, new zealand main research area sustainable architecture, building performance and indoor environmental quality address 139 vivian street, te aro campus, wellington tel. +642102850560 e-mail: aniebietabasi.ackley1@myport. ac.uk catherine teeling architect, senior lecturer faculty of creative and cultural industries, portsmouth school of architecture, university of portsmouth, united kingdom main research area urban regeneration and sustainable architecture address eldon building, winston churchill avenue, portsmouth po1 2dj tel. 023 9284 2098 e-mail: catherine.teeling@port.ac.uk dr. eugene e. atamewan architect, lecturer, member nigerian institute of architects, faculty of environmental science, department of architecture, cross river university of technology, calabar, nigeria main research area housing and sustainable architecture address department of architecture, crutech, calabar tel. +2348036602248 e-mail: geneatas@yahoo.com about the authors 59 journal of sustainable architecture and civil engineering 2016/2/15 *corresponding author: m.kosior@pb.edu.pl determination of the fracture toughness parameters of cement composite using specimens with rounded notch received 2016/06/20 accepted after revision 2016/09/16 journal of sustainable architecture and civil engineering vol. 2 / no. 15 / 2016 pp. 59-65 doi 10.5755/j01.sace.15.2.15376 © kaunas university of technology determination of the fracture toughness parameters of cement composite using specimens with rounded notch jsace 2/15 http://dx.doi.org/10.5755/j01.sace.15.2.15376 marta kosior-kazberuk bialystok university of technology, faculty of civil and environmental engineering wiejska st. 45e, 15-351 bialystok, poland the fracture mechanics parameters are used in different applications to formulae the classic criteria of failure as well as in computational models to analyze the concrete structures and other brittle materials. the parameters are determined using the specimens with notches. the study for assessing the influence of the notch curvature in specimen on fracture mechanics parameters, e.g. critical stress intensity factor, critical crack tip opening displacement and fracture energy, was performed on cement mortar as a typical quasi-brittle material. the u-shaped notches with a depth of 30 mm were formed during molding the specimens. the radius of notch curvature was changed in the range from 0.15 mm to 30.0 mm. the results obtained demonstrated that the notch curvature radius has a significant effect on the level of maximum stress and the parameters describing the cement composite resistance to cracking. therefore, the experimental determination of the fracture characteristics requires a strict definition of the test conditions. keywords: fine grained concrete, fracture mechanics parameters, u-shaped notch. the cracking process of the element of quasi-brittle material with heterogeneous microstructure (eg. cement based composites) is associated with the formation and propagation of the main crack called a critical defect. in the vicinity of defects such as fissure, air void, microcrack, etc. the local stress concentrations occur caused by external forces, which under certain conditions can cause rapid propagation of damage and total destruction of a structural member. the methods of fracture mechanics allow to describe the process of destruction of this type of material (bažant 2002, shah et al. 1995), as well as degradation which results from the impact of service life conditions (kosior-kazberuk 2012, wardeh and ghorbel 2015). notches in structural elements are places where stresses concentrate and, because of that, can trigger cracks leading to catastrophic failure or to a shortening of the assessed structural life. the phenomenon of cracking of construction and building materials is so common that there is a need to conduct the research to establish an easy-to-implement method of determining the values of parameters describing material’s resistance to cracking. introduction journal of sustainable architecture and civil engineering 2016/2/15 60 the critical stress intensity factor determined experimentally using samples with notch (jenq and shah 1991) is the fundamental material parameter of linear elastic fracture mechanics. in case of metals the procedure of determining this parameter is standardized and universally applied. the process of fracture starts up from the pre-existing sharp crack tip initiated by a fatigue loading. for cement composites and other brittle materials, fracture mechanics parameter identification requires the tests on the sample elements with pre-formed initial crack or notch. for brittle materials, such as concrete, ceramics or rocks, the process of obtainment the initial crack is difficult to control. during standard tests of quasi-brittle materials the elongate u-notches with a width from 1 to 10 mm are used, and the influence of rounded notch tip is skipped. normally the notch is formed during casting of sample, or by cutting using diamond saw (kosior-kazberuk and kazberuk 2010). the u-shaped notches obtained in this manner are 2-3 mm width and have similar notch tip rounding diameter. consequently, all other dimensions of specimen must be relatively large, which raises costs of research. this approach is easy to implement, but includes a narrow spectrum of geometry notches (cracks), and does not explain in which range of the geometry of initial defects the process of crack propagation should be analyzed based on the criteria of strength of materials, and in which – on the basis of fracture mechanics (berto et al. 2013, berto and barati 2011). most previous researches on the effects of u-notch on fracture mechanics parameters, focused on theoretical considerations rather than on test methods, were conducted using the materials such as polymethyl methacrylate (berto et al. 2013), metal alloys (berto and barati 2011, gomez et al. 2008), graphite (torabi 2013). the results of the study indicate a significant influence of the radius of the notch tip on the value of the destructive force and the process of cracking. the tests conducted using concrete samples related mainly to the effect of the notch depth on fracture characteristics (wardeh and ghorbel 2015). also, the influence of the notch radius on the fracture toughness measurements must be taken into account (gomez and elices 2006, picard et al. 2006). in case of the notches with rounded tip, i.e., those for which the value of the tip radius in relation to the depth of notch is important, the singularity of stress disappears, and therefore, the criteria of fracture based on a linear elastic fracture mechanics can not be applied even in the case of brittle materials (gomez et al. 2008). the aim of the work was the assessment of the changes in fracture toughness of cement composite samples depending on the radius of the notch initiating cracking process. the experimental investigation was conducted using the procedure in which a sample in the form of beam with formed a single notch is loaded in three-point-bending test in accordance with mode i conditions. for experimental studies to evaluate the effect of rounding notch on the fracture mechanics parameters the mortar based on portland cement (cem i 42,5 hsr na) with density 3050 kg/m3 was used as typical quasi-brittle material easy to form. fine quartz sand (0-2 mm) with density 2620 kg/m3 was used as an aggregate. the limitation of the grain size was intended to eliminate the possible effect of coarse aggregate on the fracture characteristics. the water-cement ratio (w/c) mortar was 0.35. the required workability was obtained using a superplasticizer based on modified polycarboxylate (0.8% of cement mass). the mechanical properties of mortar were determined. three beams of size 100×100×400 mm were used for flexural strength test, three cubes (100×100×100 mm) were used for the compressive strength test. three cylinders (h=300 mm, d=150 mm) were used for young’s modulus determination. the average compressive strength of mortar after 90 days of curing was 51.7 mpa, the average tensile strength was 4.01 mpa and tangent modulus of elasticity, determined from measurements of fracture mechanics parameters reached a value of 22.3 gpa. the specimens of size 400×100×100 mm were prepared. all specimens were weakened by u-notches characterized by different values of notch tip radius and the same notch depth of 30 materials and methods 61 journal of sustainable architecture and civil engineering 2016/2/15 mm (the ratio a0/d =0.30), that were formed during casting. special disposable inserts for moulds were designed. the notch radius r was equal to 0.15; 0,35 mm; 0,65 mm; 1,35 mm; 3,15 mm; 8,0 mm; 15,0 mm; to 30.0 mm were used. for comparison the specimen series with conventional notch cut using a diamond saw (width of 3 mm) were tested. each series of specimens was composed of four elements. after demoulding all specimens were stored in water at the temperature of 20±2oc for 90 days. the effect of notch tip radius r in specimen on a critical value of the stress intensity factor and fracture parameters of cement composite was analyzed. the critical stress intensity factor s ick and the critical tip opening displacement ctodc were determined according to the procedure proposed by rilem tc 89-fmt (1990), developed on the basis of the two-parameters fracture model described by shah et al. (1995). both parameters are related to the critical stress σc initiating the crack propagation and the effective length of the critical crack ac according to the following relationships: where: where g1, g2, and g3 are geometrical functions.(1) (2) (3)        b a gak c cc s ic 1 ,        b a g e a ccc c 2 4 cmod  ,        b a b a g c cc 0 3 ,cmodctod ,        b a gak c cc s ic 1 ,        b a g e a ccc c 2 4 cmod  ,        b a b a g c cc 0 3 ,cmodctod ,        b a gak c cc s ic 1 ,        b a g e a ccc c 2 4 cmod  ,        b a b a g c cc 0 3 ,cmodctod , fig. 1 fracture testing configuration and geometry of specimen the beam elements with u-notch were loaded in three-point bending test corresponding to mode i conditions. dimensions and method of loading of a test specimen was showed in fig. 1. during the test the loading force p as a function of the increase in the notch opening (notch mouth opening displacement þnmod) was recorded. the universal testing machine (mts 322) with closedloop servo control was used to achieve a stable failure of specimens. the complete load-time curve was recorded to check the stability during the test. the test was performed with constant rate of deformation, so that the maximum load was reached within 30 – 60 seconds after start of the test. fig. 2 shows the testing machine with beam specimen. the basis for determining the value necessary for the calculation of the fracture parameters was a load p-þnmod curve obtained as a result of cyclic loading and unloading of the beam with notch. the increase in the width of the notch opening was measured using a clip gauge with a base length of 5 mm. before measuring the weight of the sample was determined and its dimensions were controlled. the crack initiated in the bottom of the notch due to the influence of the tensile stresses developed until reaching a critical effective crack length ac at which an unstable development of cracks occurred leading to the destruction of the test specimen. the rate of loading was chosen so that the maximum value was reached within about 5 min. the rate was controlled by the constant rate of increment of crack mouth opening displacement. the journal of sustainable architecture and civil engineering 2016/2/15 62 applied load was automatically reduced (unloading phase) when the load passed the maximum value and was about 95% of the peak load. when the applied load was reduced to ca. 100 n, reloading was applied. the cycles of loading and unloading were repeated four times, and then the specimen was loaded up to failure. at the same time, each successive cycle, after the initial, last no longer than 1 minute. for assessment of the fracture mechanics parameters the initial loading compliance ci and unloading compliance cu were determined on the basis of the plot pþnmod (rilem 1990). the loading compliance (ci) was calculated as the inverse of the slope from 10% of the peak load until 50% of the peak load. this was estimated to be the linear elastic range and ignored any initial seating load discontinuities in the curve. the unloading compliance (cu) was the inverse of slope of the unloading curve. determined, on the basis of ci the initial elasticity modulus e was defined as the tangent modulus. the mid-span deflection δ of specimen with the applied load p were refig. 2 beam specimen with u-notch during testing corded continuously until the beam was completely separated into two halves. the fracture energy (gf) is defined as the area under the load-deflection curve per unit fractured surface area. the fracture energy of mortar tested in this experimental study, was evaluated using the equation given by rilem tc 50-fmt (1985), in which energy was calculated from load-deflection curves obtained by performing a three-point bending test where: g = 9.81 m/s2; d – beam depth; b – beam width; (4)     badmgdpgf 00 max /max    , a0 – notch depth; δmax – maximum deflection. in connection with the test, the weight of the beam m was determined and included into calculation of gf. the scatter of the calculated values of gf results from the inevitable random length of the tail region of p-δ curve and also from the uncertainty in extrapolating the curve descent to zero. to reduce the impact of factors mentioned on the scatter of gf the plot was excised when the load was approximately equal to 0.05 pmax (100÷200 n). on this basis, the value of δmax was determined. the area of the cross section of specimen, to which the total energy value was referred, was determined based on the width of the test specimen b and the depth d excluding the notch (a0 = 30 mm). initial segments of p-dnmod plots until reaching the maximum load for all radii of notch tip were showed in fig. 3. on the basis of this part of the graph the initial compliance ci was determined and the tangent elastic modulus was calculated. linear section of the initial phase of p-dnmod plot had an identical course independent of the radius of the notch in test specimen. thus, the value of the elastic modulus, determined during the tests was independent of e. the analysis of p-dnmod plots for different relative values of the radius of notch showed that the increase in e caused the increase in the length of linear section of the plots and the increase in maximum load. at the same time, the value of dnmod, corresponding to the experimentally measured maximum load pmax, increased slightly. results 63 journal of sustainable architecture and civil engineering 2016/2/15 fig. 3 initial part of p-þnmod curves vs. relative radius of notch curvature ε = r/a0 table 1 dimensionless stress r/rt for different relative radius of notch curvature ε = r/a0 ε = r/a0 r/rt 0,005 0,623 0,012 0,679 0,022 0,84 0,045 0,88 0,105 0,93 0,267 0,959 0,50 0,965 1,00 1,00 the results obtained were given in table 1 as the dimensionless stress σ/σt describing the proportion of stresses at the tip of notch to flexural strength for different relative radius of the notch tip ε = r/a0. with the increase in the radius of notch the level of destructive stress increased. for small values of ε the differences in stress values were the greatest; further the changes of stress proceeded smoothly. for large radii of curvature, i.e. ε ≥ 0,267 (r = 8,0; 15,0 and 30,0), a value of destructive stress approached the flexural strength of mortar. the fracture parameters kic and ctodc were determined on the basis of p-þnmod curves obtained for concrete specimens with various radii of notch tip. the critical values of the stress intensity factor kic as a function of the relative radius of the notch tip ε, plotted in logarithmic scale were shown in fig. 4. the critical stress intensity factor increased with increasing values of ε. the black dot in fig. 4 indicated the value kic determined using a test specimen with a conventional notch depth of 30.0 mm and a width of 3.0 mm cut using a diamond saw. for specimens with a formed u-notch the comparable values of critical stress intensity factor were obtained for relative radii of notch tip ε ≥ 0,267. the changes in ctodc (fig. 5) were not as intensive as the changes in kic and the character of the relationship was different. the uniform increase of ctodc with the increase in radius of a notch tip was observed. the elastic modulus of mortar tested was constant during the test, thus the main parameter influenced the value of ctodc (rilem 1990) was pmax. the significant parameter of non-linear fracture mechanics is the fracture energy gf, defined as the amount of energy absorbed within the zone of destruction, per unit area (bažant 2002). fracture energy characterized the process of cracking and post-cracking strain fig. 4 critical stress intensity factor kic vs. relative radius of notch curvature ε =r/a0, the black dot indicated kic determined using the conventional specimen with saw cut notch fig. 5 critical crack tip opening displacement ctodc vs. relative radius of notch curvature ε =r/a0, the black dot indicated ctodc determined using the conventional specimen with saw cut notch journal of sustainable architecture and civil engineering 2016/2/15 64 softening of material after reaching the maximum stress. the dependence of fracture energy gf on the relative radius of the notch ε was shown in fig. 6. the black dot indicated the amount of energy required to failure of the specimen with notch cut with a saw. the increase in gf was the result of the increase in pmax and the increase in kic. for ε ≥ 0,267 the changes in gf were negligible. the amount of energy needed to fracture process initiation increased with the increase in the radius of the notch. fig. 6 fracture energy gf vs. relative radius of notch curvature ε=r/a0, the black dot indicated gf determined using the conventional specimen with saw cut notch as it was shown in figs 4-6 the values of parameter determined in the same load conditions for specimens of the same geometry but with notch cut using a diamond saw were significantly different from the results obtained for samples with notch with a rounded tip. experimental determination of fracture mechanics parameters of cement composites requires strictly defined test conditions. for blunted notches – i.e. when the notch radius is no longer negligible – the elastic stress singularity disappears and the fracture criterion of linear elastic fracture mechanics is no longer applicable, even for brittle material as cement mortar. the results obtained confirmed the dependence of fracture mechanics parameters on the radius of the notch tip in the test specimen. with the increase in radius the extension of the linear segment of initial phase of the plot pþnmod and the increase in the value of maximum load were observed. the values of the parameters analyzed: critical stress intensity factor, critical crack tip opening displacement and fracture energy also increased. the main reason for these changes was the increase in the energy required to initiate the process of cracking at the tip of rounded notch. moreover, the way of notch forming, and as a result the shape of crack tip has a significant effect on fracture process initiation and fracture parameters. the results of the research are the basis for identifying the parameters of theoretical models of concrete elements cracking. conclusions the minister of science and higher education has supported the research work presented in this paper, project number s/wbiis/2/12.acknowledgment bažant z.p. concrete fracture models: testing and practice. engineering fracture mechanics, 2002; 69: 165-205. http://dx.doi.org/10.1016/s00137944(01)00084-4 berto f., campagnolo a., elices m., lazzarin p. a synthesis of polymethylmethacrylate data from u-notched specimens and v-notches with end holes by means of local energy. materials and design, 2013; 49: 826-833. http://dx.doi.org/10.1016/j.matdes.2013.01.074 berto f., barati e. fracture assessment of u-notches under three point bending by means of local energy density. materials and design, 2011; 32: 822-830. http://dx.doi.org/10.1016/j.matdes.2010.07.017 references gomez f.j., elices m. fracture loads for ceramic samples with rounded notches. engineering fracture mechanics, 2006; 73: 880-894. http://dx.doi. org/10.1016/j.engfracmech.2005.11.005 gomez f.j., elices m., berto f., lazzarin p. a generalised notch stress intensity factor for u-notched components loaded under mixed mode. engineering fracture mechanics, 2008; 75: 4819-4833. http:// dx.doi.org/10.1016/j.engfracmech.2008.07.001 jenq y.s., shah s.p. features of mechanics of quasi-brittle crack propagation in concrete. international journal of fracture, 1991; 51: 103-120. http:// dx.doi.org/10.1007/978-94-011-3638-9_8 65 journal of sustainable architecture and civil engineering 2016/2/15 kosior-kazberuk m. effects of interaction of static load and frost on damage mechanism of concrete elements. journal of sustainable architecture and civil engineering, 2012; 1: 40-45. http://dx.doi. org/10.5755/j01.sace.1.1.2616 kosior-kazberuk m., kazberuk a. determination of the fracture toughness parameters of quasi-brittle materials using cylindrical samples. ceramics materials, 2010; 62: 244-248. picard d., leguillon d., putot c. a method to estimate the influence of the notch-root radius on the fracture toughness measurement of ceramics. journal of the european ceramic society 2006; 26: 1421-1427. http://dx.doi.org/10.1016/j.jeurceramsoc.2005.02.016 recommendation tc 89-fmt rilem. determination of fracture parameters (kic and ctodc) of plain concrete using three-point bend test. materials and structures, 1990; 23: 457-460. http://dx.doi. org/10.1007/bf02472029 recommendation tc 50-fmt rilem. determination of the fracture energy of mortar and concrete by means of three-point bend tests on notched beams, materials and structures, 1985; 18: 287-290. http:// dx.doi.org/10.1007/bf02472918 shah s.p., swartz s.e., ouyang ch. fracture mechanics of concrete: applications of fracture mechanics to concrete, rock and other quasi-brittle materials. new york: john wiley & sons, inc.; 1995. torabi a.r. sudden fracture from u-notches in finegrained isostatic graphite under mixed mode i/ii loading. international journal of fracture, 2013; 181: 309-316. http://dx.doi.org/10.1007/s10704-0139832-5 wardeh g., ghorbel e. prediction of fracture parameters and strain-softening behavior of concrete: effect of frost action. materials and structures, 2015; 48: 123-138. http://dx.doi.org/10.1617/s11527013-0172-8 marta kosior-kazberuk associate professor bialystok university of technology, faculty of civil and environmental engineering, department of building structures main research area concrete technology, durability of concrete structures, fracture mechanics of concrete, concrete structures with non-metalic reinforcement address wiejsta str. 45e, 15-351 bialystok, poland tel. +48 797 995 935 e-mail: m.kosior@pb.edu.pl about the author 57 journal of sustainable architecture and civil engineering 2015/3/12 corresponding author: j.kucinskiene@kvk.lt experience areas landscape design features: visualization possibilities received 2015/07/03 accepted after revision 2015/08/29 journal of sustainable architecture and civil engineering vol. 3 / no. 12 / 2015 pp. 57-64 doi 10.5755/j01.sace.12.3.13019 © kaunas university of technology experience areas landscape design features: visualization possibilities jsace 3/12 http://dx.doi.org/10.5755/j01.sace.12.3.13019 introduction jurga kučinskienė, gintaras kučinskas klaipeda state university of applied sciences, faculty of technologies bijunu str.10, lt-91223, klaipeda, lithuania we understand 80 percent of the surrounding environment by sight, and 70 percent of experience landscape areas consist of plants. when planning experiences landscape area we use number of trees and shrubs shoots, stems, bark, leaves, flowers, fruits ornamental characteristics: colour, texture, shape or size. these measures through visual sense in the experience landscape areas can provide a unique look and mood. the aim of this article — review of the use of visualization’s possibilities in the landscape design of the experience areas. this study is done in systematic and comparative analysis methods. visual sense in environment without some work of art is also expressed through some trees and bushes characteristics, features (colour, texture, shape and size) in the planning of experience landscape areas. these measures may take very specific purpose to identify the desired image and mood in the environment experience areas landscape design. moreover, in the planning process we not only work with the drawings, but also provide visualizations to help realize our proposed ideas, to feel those experiences from the planning process, which helps to convince the customer. the common understanding of the green areas landscape design projects depends on how designer and customer can work on their different experiences/views to achieve the desirable result. visualization projects of experience landscape areas we can divide into several possible categories depending on the tools and desired results. visualization usually is created as an additional tool during the project or as an additional part of the project, which would increase the attractiveness. results depend on selected different tools and quality of the visualization. the most common problems occurred during the work with visualizations tool selection, project complexity mismatch with a computer programs and tools used to create forms; or content restriction. keywords: experiences areas, visualization, 3d modelling, rendering, landscape design. a man learns about environment through the senses: sight, hearing, smell, taste, and touch. when you cannot see well, you prefer using other senses. generally speaking about the experiences we usually think about entertainment experience, but the fact is that such areas may be very different (tuch et al., 2008; kučinskienė, baravykaitė, 2012): public space (recreation centres, shopping centres, restaurants, hotels, etc.), education space (museums, heritage sites, research centres, etc.), the other space (libraries, hospitals child units in residential areas, etc.). it may also be relatively natural (which consists primarily of natural elements of the natural environment) or have urban landscape components. the planning of experience area starts with designing process. without some means of artistic expression (the proportions, zoom, accents, contrast, and other common composite measures) environment visual sense can be created using some trees and bushes characjournal of sustainable architecture and civil engineering 2015/3/12 58 teristics, features colour (leaves, needles, stem, branches, shoots, flowers, fruit), texture (crown, trunk, branches, stems), shape (crown, leaves, flowers, fruits), size (plant and its branches, leaves, flowers, berries, fruits). these measures affect experience areas of landscape design in different ways. therefore it may be used for a specific purpose in the environment to identify the desired image and mood. moreover, in the planning process we not only work with the drawings, but also provide visualizations to help customer realize our proposed ideas, to feel those experiences from the beginning of the planning process, which also seeks to convince the customer. the common understanding of the green areas landscape design project depends on how designer and customer can work on their different views to achieve the desirable result. the aim of the article — review of the use of visualization possibilities in the landscape design of the experience areas. the experience areas landscape design visualizations were analysed and categorized in lithuanian and foreign literature. analysis of the landscape design visualization possibilities, comparison of 3d modelling software. this study is carried out in systematic and comparative analysis methods, using 10 years of personal experience. methods results depending on the tools and desired result of experience areas landscape visualization projects we can divide into several categories. visualization usually is created as an additional tool during the project, or as an additional part of the project, which would increase the attractiveness of the project and visualization. what tools to choose depends on the purpose and visualization performance quality (e.g. fig. 1). fig. 1 example of project rendered with commercial landscape design software (rendered with chaos group v-ray) the aims of creation of landscape design visualizations landscape design visualization projects are designed to meet a number of objectives. the most common objectives are space allocation, project vision in the perspective representing plants’ and objects’ heights rating or shading zones. for this purpose it is enough to use basic, free tools, such as a free software trimble sketchup (sketchup, 2015), where you have to face lack of speed and concerns about data well-being. when visualization is created to achieve this goal, it becomes another designing tool. often the customer does not even see visualization – it is used only at designing time. in this case the desired result is to create visualization project for the presentation or explanation, it facilitates the design (makes it three-dimensional), but increases time costs significantly. also visualization can be used for project lighting system control. in this case basic tools are not enough, therefore you have to use specialized rendering solutions that simulate light sources too (such as the chaos group v-ray, pov-ray, kerkythea or other (kerkythea, 2015; pov–ray, 2015, v–ray, 2015). usually this type of visualization is extremely realistic. it is often used to introduce the project, to attract customers and represent the author of the project (e.g. fig.2, fig.3, fig.4). this type of visualization gives an advantage to the project, making the project more attractive to the customer. on the other hand this type of visualization requires additional software (sometimes full 3d drafting in a separate program such as autodesk 3ds max (autodesk 3ds max, 2015) or similar) and additional computing resources. generating one video can take from several minutes to several hours or days depending on the complexity of objects and materials. therefore, it can be said that higher quality visualizations make project more expensive (gill, 2013). fig. 2 example of project rendered with commercial landscape design software (rendered with realtime landscaping architect) fig. 3 example of project made and rendered with free 3d modelling and rendering software (rendered with kerkythea) fig. 4 example of project rendered with commercial rendering software (rendered with chaos group v-ray) the methods of the creation of visualization usually landscape designers are working with “normal” tools – the most commonly used are autodesk autocad or similar software packages. these software tools are very versatile, allowing the users to realize various different ideas. the negative side to most drawing and design programs are that it is more convenient to use flat (2d) mode. creating experience areas of landscape design project in “traditional” way, you have to perform several steps – 2d design environment; project transfer to 3d environment; work on surfaces, environment and animation; rendering. often greenery designers considering time costs and resources required for the expected result of the project, decide against using visualization (al-kodmany, 2002). depending on the tools and goals, landscape design projects’ visualizations can be classified into several possible methods: _ visualization created as an additional tool for raising awareness of the project. it is based on the use of trimble sketchup or similar program (e.g. fig.5). it is very easy to use, it is fast, have the possibilities to work with the online libraries of objects, and have ability to check the lighting project at different times of day and year. this and similar programs can generate images looking more like drawings rather than high quality environment rendering, but the program works quickly, the results are visible straight away. _ visualization of the project designed to increase the attractiveness. in this case there are several possible development paths. available immediately to design in a 3d environment (using both: conventional design programs e.g. autodesk autocad and ending in any journal of sustainable architecture and civil engineering 2015/3/12 60 three-dimensional design program). the project is transferred to the rendering program (sometimes in the rendering plug-ins inside the design program), where users set up the textures and lighting. also the animation options are available. this stage is completed by generating the video or animation (series of images). this way rendering is similar to reality images (with regard to the reflections, transparency, light fractures, surface roughness, etc). but this method of rendering requires a lot of computer resources and is time consuming. other way – design created in traditional 2d way and then transferred to the three-dimensional program. in this case the transfer might reduce the details of the project, leaving only those objects that will be visible in visualization. on the other hand this way needs more time and basically once again replicates the project in three-dimensional space. it depends on the designer’s skills and taste which method to chose. nonetheless, it is advisable to evaluate rendering time and resources and decide whether it is worth to load the project into a three-dimensional design. the other similar way is possible, when visualization is used as an additional and optional part of the project. in this case, the visualization is generated only when required by customer. _ there is another way – to outsource project to outside companies which provide rendering services. in this case the designer saves time, but purchasing rendering services significantly increases the total cost of the project. fig. 5 different imaging techniques with trimble sketchup and kerkythea: trimble sketchup without and with colours, and kerkythea at night and at day visualization creation tools visualization development tools according to the nature of the project development are divided into several groups: _ 3d modelling tools (e.g. table 1, table 2). these tools allow you to create three-dimensional scenes. most programs can import / export models or scenes into many popular 3d and 2d formats. some programs can prepare simple table 1 free 3d modelling software program name license visualization generating opportunities 3d slash freemium yes anim8or freeware yes autodesk 123d freeware no blender gnu gplv2+ yes caligari truespace freeware yes daz 3d studio freemium yes freecad gnu lgpl yes newtek lightwave 3d trialware yes openscad gnu gpl yes pixologic sculptris freeware no trimble sketchup freemium yes wings 3d bsd yes zanoza zmodeler freeware yes visualizations or use sophisticated rendering plugins. software’s advantages– free, easily absorbed, have a huge online library of objects and an online library of plug-ins. for better quality visualization you can use plug-ins (such as the chaos group v-ray (e.g. table 4.)) or external applications (such as kerkythea (e.g.table 3.)) aid. simple projects visualization tool kit “trimble sketchup + kerkythea” is completely sufficient. disadvantages are: applications defects are very awkward; 61 journal of sustainable architecture and civil engineering 2015/3/12 limited opportunities to work with complex and irregular graphics. it is also problematic without the use of add-ons to cover the complex surface textures. _ generation of visualization (rendering) tools (e.g. table 3, table 4). these tools work as plug-ins or as separate programs with imported three-dimensional models. most programs allow you to import the majority of the most popular models in 3d formats. all programs have the ability to save the generated visualization as a picture or series of pictures, some even allows at once transform sequence of pictures into a video format. if you chose another tool for the visualization job, here the best programs for this purpose are autodesk 3d studio max products using chaos group v-ray, or pov-ray generation visualization plugins. these programs are professional three-dimensional modelling tools and that gives an advantage. disadvantages – a complex program management, time consuming, program costs. _ specialized landscape design programs. it can be used on its own (such as realtime landscaping architect) or as a plugin (like plantare – autodesk autocad plug-in). almost all of these programs have 3d visualization possibilities. some of them can create videos. most table 2 commercial 3d modelling software program name visualization generating opportunities program name visualization generating opportunities animation: master yes esri city engine no autodesk 3ds max yes inivis ac3d no autodesk autocad yes maxon cinema 4d yes autodesk inventor yes nevercenter silo no autodesk maya yes pilgway 3d-coat yes autodesk revit yes pixologic zbrush yes autodesk soft image yes realsoft 3d yes autodessys form-z yes rhineceros 3d yes cheetah3d yes remograph remo 3d yes daz 3d bryce yes side effects software houdini yes daz 3d carrara yes solidworks yes daz 3d hexagon no strata 3d yes electric image animation system yes the foundry visionmongers modo yes electric rain swift 3d no view point 3d yes software license platform windows os x linux art of illusion gpl yes yes yes blender gpl yes yes yes kerkythea freeware yes yes yes lux render gplv3 yes yes yes picogen gplv3 yes no yes pixie gpl yes yes yes pov-ray agplv3 yes yes yes radiance bsd yes yes yes of these programs are used for creating visualizations. these programs have exclusive feature – the ability to add new plants to existing database. from specialized applications the most suitable for green design is realtime landscaping architect (realtime…, 2015). table 3 free rendering software journal of sustainable architecture and civil engineering 2015/3/12 62 software platform windows os x linux autodesk 3ds max yes no no autodesk maya yes yes yes autodesk softimage yes no yes chaos group v-ray yes yes yes daz 3d bryce yes yes no daz 3d carrara yes yes no e-on vue yes yes no glare technologies indigo renderer yes yes yes maxon cinema 4d yes yes no na research 3delight yes yes yes newtek light wave 3d yes yes no next limit maxwell render yes yes yes nvidia mental ray yes yes yes pixar photorealistic renderman yes yes yes realsoft 3d yes yes yes table 5 commercial 3d modelling software for landscape design to po f en ce p ea k lis t o u tc o m es p la nt e nc ycl o pe di a 3d p la nt s 2d p la nn in g 3d p la nn in g realtime landscaping architect yes yes yes yes yes yes yes yes home & landscape design yes yes yes yes yes yes yes yes home designer suite yes yes yes yes yes yes yes yes landscape deck & patio yes yes yes yes yes no yes yes hgtv ultimate home design yes yes yes yes yes yes yes yes turbo floor plan 3d home & landscape yes yes yes yes yes yes yes yes total 3d home, landscape & deck yes yes yes yes yes no yes yes home & landscape design yes yes yes yes no no yes no hgtv home & landscape platinum yes yes no yes yes yes yes yes landscape vision no no no no yes no yes no table 4 commercial rendering software this program allows you to work with both: flat plans and with the three-dimensional models, allows making corrections simply in 3d view window. there are broad plants, objects, and textures libraries, buildings, swimming pools, fences flowerbeds development assistants (wizards), you can import and export flat and three-dimensional objects and many other useful features. the program also allows you to move camera around inside the project and enables you to create and export videos from ‘inside’. typical problems of the creation of visualizations the development of projects visualizations of landscape design experience areas faced with a number of problems. in most cases at beginning there is a question: “which software tool to choose?” it depends on few criterias: first of all designer’s financial position. then we also need to take into account such factors as the capacity of the existing computer equipment, rendering time and designer’s skills. the best way is to use specialized tools (such as realtime landscaping). these tools allow two-dimensional design and three-dimensional images. besides, as a rule, this type of application has its own plant libraries. designer choosing this type of programs in order to avoid problems in the future, should pay attention to the following points: _ program interface. is there a native language support? is it possible to generate drawings and reports in native language? 63 journal of sustainable architecture and civil engineering 2015/3/12 _ plant library. how much and what kind of plants there are? is there a description of the plant? does the library have plants which are growing in the planning region? is it possible to supplement the library (the same or purchase additional packages)? is it possible to rename or add plant names? is it possible to import / export plant library? _ are there images of three-dimensional objects and ability of import? is it possible to upload a background image? _ is it possible to generate lists automatically (price, quantities of work anticipated and so on)? can they be generated in native language? _ what kind of license the program has (or additional cost software updates and additions to the library)? do you have to pay extra if you change the operating system (or example upgrading)? _ price for the software and upgrades. if you choose not to use specialized tools, the main criteria when choosing a tool should be considering how easy to use it and availability of skills. most of the three-dimensional modelling programs have plug-ins that allows generating plants, but when you need to create a specific known plant, these plug-ins work in very poor quality. therefore when choosing 3d modelling tool you should consider its simplicity (example – trimble sketchup) and versatility popularity (such as blender). nevertheless it should emphasize simplicity and efficiency rather than modelling capabilities. the same applies to the rendering applications. there are a few evaluation criteria: _ material library. usually, rendering program already has small library of the materials, but hardly enough to create even the simplest visualization. therefore it should be noted that you might find materials for the selected program libraries. _ additional program options (environmental generation, import of 3d and flat objects, etc.). _ rendering speed. it is not an objective measure, it depends on many settings of the 3d scene and computer resources, but subjectively it can be said which programmes are working slowly, which faster. speed is affected by different rendering algorithms. another common problem is pc’s inability to cope with huge amounts of data. if you create a complex project, it is likely that the computer will not manage, video start jerking, and slows down. to avoid this issue, we should avoid complex plant models consisting of loads of polygons. another way is to hide all unnecessary information (if the modelling or rendering program supports layers feature). another common problem faced by designers when preparing visualizations a long time of image or video rendering. this can take anywhere from a few minutes to several hours or even days. when preparing the visualization designer should pay attention to several things: _ if it is possible we have to avoid many small parts of objects (for example, if the plant is not very close to the camera use sheet with a transparent texture of leaves). more clear details – more time to create the image. _ using only the necessary light sources. more light sources the longer it takes to create the image. _ deciding on the reflecting and refracting objects. more of these objects leads to slow image generation. _ availability of online rendering services. it allows computer resources only to be used in designing, but on the other hand, these services are rather expensive and that raises the total cost of the project. visualisation tools can not realize all designing ideas. sometimes the tool itself sets draft form and content restrictions. for example if it was decided to use landscape design program trimble sketchup, user should avoid irregular shapes and curved surfaces. this problem can be solved by using specific tool functions or another simple way make a few sketches by hand. journal of sustainable architecture and civil engineering 2015/3/12 64 1 visualization is usually created as an additional tool during the experience areas landscape design project, or as an additional part of this project, which would increase the attractiveness of the project and visualization. results depend on selected different tools and quality of visualization. 2 the visualizations can be created in several ways. using specialized programs for their creation process is automated. in the case of universal design tools separately generate 3d model and transfer it into the program, which is used to generate visualizations image. 3 from the list of software tools, according to one of the objectives described above, it is possible to select the most appropriate programs: for the creation of the operational visualization, the shadow zones or determination of the fast visualization, the best product at this moment is program trimble sketchup. for green design the most suitable from specialized applications is program called realtime landscaping architect. this program allows you to work both with flat plans and the three-dimensional (3d) models, allows making corrections simply in the 3d view. the designer should not do high-quality visualization, there are specialized companies offering rendering services. if for whatever reason, you have decided to choose a tool for visualization, so the programs for this purpose would be autodesk 3d studio max products, with chaos group v-ray, or pov-ray rendering plug-ins. 4 the most common problems in the creating visualizations – tool selection, project mis-match with a computer programs and/or the tool used to create forms, content restriction. conclusions al-kodmany, k. visualization tools and methods in community planning: from freehand sketches to virtual reality. journal of planning literature, 2002; 17(2): 189–211. http://dx.doi. org/10.1177/088541202762475946 autodesk 3ds max. 2015 [interactive]. internet link: http:// www.autodesk.com/products/3ds-max/overview. gill, l. an analysis of usage of different types of visualisation media within a collaborative planning workshop environment. environment and planning b: planning and design, 2013; (40): 742–754. kerkythea. 2015 [interactive]. internet link: http:// www.kerkythea.net/cms/. kučinskienė, j., baravykaitė, d. potyrių vietovės – šių dienų planavimo iššūkis [experience areas – today’s planning challenge]. miestų želdynų formavimas. mokslo darbai, 2012; 1(9): 95–101. pov–ray. 2015 [interactive]. internet link: http:// www.povray.org/. realtime landscaping architect. 2015 [interactive]. internet link: https://secure.ideaspectrum.com/ arch_overview.php. sketchup. 2015 [interactive]. internet link: http:// www.sketchup.com/. tuch, l., mayer j. (editors). architecture and place making. 2008; june: 1–11. v–ray. 2015 [interactive]. internet link: https:// www.vray.com/. jurga kučinskienė dr., associate professor klaipeda state university of applied sciences, faculty of technologies main research area experience areas planning, landscape design. address bijunu str.10, lt-91223, klaipeda, lithuania tel. +370 65018320 e-mail: j.kucinskiene@kvk.lt gintaras kučinskas lecturer, head of information technologies department klaipeda state university of applied sciences, faculty of technologies main research area 3d visualizations. address bijunu str.10, lt-91223, klaipeda, lithuania tel. +370 69829779 e-mail: g.kucinskas@kvk.lt references about the authors 65 journal of sustainable architecture and civil engineering 2017/2/19 *corresponding author: danute.palubinskaite@ktu.lt alkaline activation of hybrid cements binders based on industrial by-products received 2017/03/27 accepted after revision 2017/05/25 alkaline activation of hybrid cements binders based on industrial byproducts jsace 2/19 http://dx.doi.org/10.5755/j01.sace.19.2.17836 vytautas bocullo, danutė vaičiukynienė* kaunas university of technology, faculty of civil engineering and architecture studentų st. 48, lt-51367 kaunas, lithuania aras kantautas kaunas university of technology, faculty of chemical technology, radvilėnų rd. 19, kaunas 5025 ruben p. borg, charlo briguglio department of construction & property management, faculty for the built environment built environment building, room 213, university of malta, msida, msd 2080, malta journal of sustainable architecture and civil engineering vol. 2 / no. 19 / 2017 pp. 65-73 doi 10.5755/j01.sace.19.2.17836 © kaunas university of technology introduction environmentally friendly building materials are becoming increasingly relevant in civil engineering in view of their contribution toward sustainable development. this research is focused on hybrid geopolymer concrete (geopolymer with ordinary portland-cement (opc) additive) with the objective of analysing strength development. in this research, hybrid geopolymer concrete, manufactured using biomass bottom ash, fly ash and production waste from the manufacture of aluminium fluoride (silica gel) with 4 different amounts of opc (0%, 5%, 10% and 15%) is studied. each blend is cured at a temperature of 50 0c and the material is tested after 7, 14 and 28 days. x-ray powder diffraction and energy-dispersive x-ray spectroscopy were used as investigation methods. the purpose of research was to study the chemical composition and the strength development in hybrid geopolymer concrete made from opc and the industrial by-products mentioned above. keywords: alkali – activated cements, fly ash, geopolymer, hybrid concrete. ordinary portland-cement (opc) is the most common building material in the world (turner and collins 2013)an alternative binder based on fly ash (a fine waste collected from the emissions liberated by coal burning power stations, but manufacturing opc results in significantly high energy consumption, due to the high temperatures required. production of 1 t of opc produces nearly 1 t of co2, which all in all accounts for around 7% of annual co2 emissions (turner and collins 2013) an alternative binder based on fly ash (a fine waste collected from the emissions liberated by coal burning power stations. this is not only environmentally unfriendly due to the high carbon footprint of the material, but can have significant economic disadvantages due to additional taxes on products (turner and collins 2013)an alternative binder based on fly ash (a fine waste collected from the emissions liberated by coal burning power stations. all of this encourages further research on alternative binders instead of opc. geopolymer concrete (gc) is a relevant alternative to opc. geopolymer concrete can significantly reduce the amounts of opc consumed. in addition different production wastes (like fly ash, high furnace slag and any other waste material that has high quantities of sio2 and al2o3) can be utilized during manufacturjournal of sustainable architecture and civil engineering 2017/2/19 66 ing of the concrete. research suggests that gc has a higher resistance to fire, and improved performance at elevated temperatures (abdulkareem et al. 2014)mortars and lightweight aggregate geopolymer concrete (lwagc and in the case of acid attack (ariffin et al. 2013). recently more attention has been given to research in geopolymer concrete containing opc as an additive. these cements form when blends containing low proportions of cement and high proportions (60-70 %) of mineral additions (slag, fly ash or metakaolin) are alkali activated. according to posi et al. (2016) the incorporation of opc enhances the strength development of lightweight geopolymer concrete with a slight increase in the density. posi et al. determined the optimum opc content as 10% opc replacement level of fly ash. the optimum curing temperature curing proposed was 60 °c. concrete with a density of 1400 kg/m3 and a strength of 14.5 mpa was obtained using a similar mix design with 10% opc and curing temperature set at 60 °c. garcía-lodeiro et al. reviewed the fundamental chemistry governing these new reactive systems. the authors also analyses the nature of the reaction products formed and their compatibility under different reaction conditions (2012). in the research the reaction mechanism involves a number of stages in which the original gels form in the opc hydration, c-s-h gel and the gel precipitated in the alkali activation of aluminosilicates, n-a-s-h gel, evolve to c-a-s-h and (n,c)-a-s-h respectively (inés garcía-lodeiro et al. 2012). pangdaeng et al. (2014) stated that the use of opc as additive had improved the properties of high calcium fly ash geopolymer. the strength increased due to the formation of additional c–s–h and c–a–s–h gel. curing conditions significantly affected the properties of geopolymers. c-s-h/n-a-s-h mix of gels precipitating, did not precipitate in a pure state. rather their composition was affected by the presence of dissolved species. in the presence of aluminium c-s-h gel development was as follows: c-s-h → c–(a)–s–h → c-a-s-h, whilst in the presence of calcium, n-a-s-h gel evolved as follows: n-a-s-h → (n,c)-a-s-h → c-a-s-h. this last conversion is not complete in these systems because the amount of calcium present is thought to be insufficient (i. garcía-lodeiro, fernández-jiménez, and palomo 2013). nath and sarker (2015) used opc to improve the setting and early strength properties of low calcium fly ash geopolymer concrete cured at room temperature. in the research they concluded that the presence of opc accelerated the geopolymerisation reaction and the compactness of the gel increased with an opc content (p. nath and sarker 2015). shinde and kadam (2016) reported that gc with opc gives better compressive strength when compared to gc cured at ambient temperature. in this article the development of strength and the chemical composition of hybrid gc with opc and additive from biomass bottom ash (bmba), coal fly ash (fa) and production waste of aluminium fluoride (pw) is studied. the aim of the research is to analyse how additional opc affects the chemical composition and the development of strength during the first 28 days. the mineral composition of the material was analysed through x-ray diffraction (xrd) using on the “d8 advance” diffractometer (bruker axs, karlsruhe, germany). the device parameters were set as follows: tube voltage 40 kv; current 40 ma the x-ray beam filter ni 0.02 mm, scanning range 2θ = 3–60°. diffraction patterns were recorded in a bragg-brentano geometry using a fast counting detector “bruker lynxeye” based on silicon strip technology. samples for chemical composition analysis (xrd) were prepared separately without aggregate to avoid peaks that belong to minerals such as quartz in the sand aggregate. these samples were prepared keeping the same proportions and molar ratios as for the mortar samples and kept in same curing conditions. the xrf analysis of raw materials were performed on the fluorescence spectrometer “s8 tiger” (bruker axs, karlsruhe, germany) operating at the counter gas helium 2 bar. the compressive and flexural strength of mortar samples was determined using a hydraulic machine “tonitechnik 2020” at 7, 14 and 28 days. the mechanical properties including compressive and flexural strength of samples were determined in accordance to bs en 1961:2005. the sample size, load rate and other experimental parameters refer to the standard. methodology 67 journal of sustainable architecture and civil engineering 2017/2/19 sio2 and al2o3 sources three different industrial by-products, were used as raw materials. all materials used were a– source of sio2 and al2o3; main components of geopolymer chains. the raw materials used were the following: biomass (timber) bottom ash (bmba), coal fly ash (fa) and alf3 production waste (pw). bmba was sourced from a lithuanian biofuel boiler house. this type of ash contains large amounts of cao. the xrd analysis for this material (fig. 1) shows peaks of mullite and quartz and also the halo peak at 2θ 25o – 35o indicates the presence of amorphous sio2. its chemical composition is given in table 1. materials fig. 1 xrd analysis 0 10 20 30 40 50 60 in te ns ity , a . u . 2, deg. fa pw q cc cc q q ca ccca ca q q q bmba z z m m m mm m z m m m q q q a aaaa aa a aaa aa a a aa q q t t t t ttt t opc b s bsb d d d d d coal burning fa is one of the most popular raw materials for geopolymer concrete due to its near perfect chemical composition: fa contains large amounts of sio2 and al2o3. these oxides form minerals of quartz and mullite according to the xrd analysis. amorphous sio2 forms a halo peak at 2θ 20o – 30o. since annual fa output is over 500 mt it is important to utilize this waste rather than landfill it. the chemical compositions of this material are given in table 1. alf3 production waste consists of sio2·nh2o, where sio2 is in the amorphous state. alf3 production waste is a silicahexaflouride acid neutralisation product. this acid is obtained from the manufacture of phosphoric acid. the silicahexaflouride process reaction (1) is as follows: (1) the xrd analysis shows that the material consists of crystalline alf3 · 3.5 h2o (fig. 1). the “halo” peak at 2θ 20o – 30o in the xrd analysis indicates the presence of amorphous sio2. the chemical composition is presented in table 1. notes: a alf3 · 3.5h2o, m – mullite, q – quartz, t – alite, d – belite, b –brownmillerite, s – bassanite, z anorthoclase, ca – calcium oxide, cc – calcium carbonate. journal of sustainable architecture and civil engineering 2017/2/19 68 table 1 chemical composition of raw materials (xrf analysis) oxide amount, % oxide amount, % fa bmba pw opc fa bbf pw opc cao 3.683 48.978 0,42 57.4 zro2 0,147 0,039 0 0.016 sio2 49.468 22,39 72,23 14.3 so3 0,921 0 0 4.70 na2o 0,945 0,281 0 0 zno 0,05 0,041 0 0 al2o3 27.452 2.509 5,68 3.63 tio2 1.658 0,328 0 0.231 mno 0,063 0,347 0 0.0428 cuo 0,027 0,02 0 0 mgo 1.699 8.286 0 2.36 nio 0,031 0 0 0 k2o 4.539 8.686 0 1.33 pbo 0,038 0 0 0 fe2o3 7.379 2.179 0,66 3.29 cl 0 0,04 0 0 bao 0,436 0,161 0 0 rb2o 0 0,024 0 0 p2o5 1.310 5.048 0 0.392 f 0 0 21,01 0 sro 0,106 0,06 0 0.0817 aggregate standard bs en 196-1 sand was used as aggregate for mortar. standard sand is natural siliceous sand consisting mostly of rounded particles with silica content of at least 98%. sand is thoroughly washed, dried and accurately graded. the grading range is provided by manufacturer and presented in table 2. table 2 grading range of aggregate size in mm cumulative retained, % 2,00 0 1,60 7 ± 5 1,00 33 ± 5 0,50 67 ± 5 0,16 87 ± 5 0,08 99 ± 1 portland-cement portland-cement is used as additive to contribute through additional c-s-h gel in the geopolymer concrete system (yip et al. 2008). this is expected to improve the mechanical properties (flexural and compressive strength). in this research cem i 42.5 r is used. the xrd analysis shows the presence of alite, belite, brownmillerite and bassanite – typical clinker minerals (fig. 1). in this research prisms (size 40 x 40 x 160 mm) were tested for the flexural and compressive strength. there were 9 prisms produced for each batch and these were tested after 7, 14 and 28 days. during the experimental period, the prisms were kept in the oven at a temperature of 50 °c. an elevated temperature is proven to have a positive effect on geopolymerisation (s. k. nath et al. 2014). the composition of the mixtures is presented in table 3. results and discussion additional opc additive had different effects on the samples produced using different materials (fig. 2, fig. 3). in most of the cases opc additive contributed significantly in improving the compressive (fig. 3) and flexural strength (fig. 2) especially when the raw material was fa and pw. the s control mix (0 % opc) of the fa samples achieved 5.75 mpa flexural (fig. 2a) and 29.67 mpa compressive strength (fig. 3a) after 28 days. samples with 5% opc additive achieved 6.02 mpa flexural (fig. 2b) and 44.60 mpa compressive (fig. 3b) strength. furthermore, within 14 days these samples reached 93% of the final flexural and 98% of the final compressive strength, while control samples reached only 59% and 61% respectively. fa samples with 15% substitute of opc gained the biggest strength: after 28 days flexural strength was 8.02 mpa and compressive strength 50.99 69 journal of sustainable architecture and civil engineering 2017/2/19 table 3 mixtures composition mixture design mix 1 mix 2 mix 3 mix 4 fa geoplymer aggregate, g 1350.00 water, g 244.46 naoh, g 171.85 fa, g 740.04 703.04 666.04 629.04 opc, g 0.00 37.00 74.00 111.01 sio2/na2o molar ratio 2.70 2.61 2.52 2.43 al2o3/sio2 molar ratio 0.33 0.32 0.32 0.32 cao/sio2 molar ratio 0.08 0.14 0.21 0.28 bmba geoplymer aggregate, g 1350.00 water, g 327.53 naoh, g 95.78 bmba, g 740.04 703.04 666.04 629.04 opc, g 0.00 37.00 74.00 111.01 sio2/na2o molar ratio 2.24 2.21 2.17 2.13 al2o3/sio2 molar ratio 0.07 0.07 0.07 0.07 cao/sio2 molar ratio 2.34 2.41 2.47 2.54 pw geoplymer aggregate, g 1350.00 water, g 244.46 naoh, g 214.00 pw, g 740.04 703.04 666.04 629.04 opc, g 0.00 37.00 74.00 111.01 sio2/na2o molar ratio 3.33 3.20 3.06 2.93 al2o3/sio2 molar ratio 0.05 0.05 0.05 0.05 cao/sio2 molar ratio 0.01 0.05 0.1 0.15 mpa, which amounts to an additional 20 mpa (fig. 3d) when compared to samples without additional opc. similar observations can be noticed in samples with 15% opc additive (fig. 2d and fig. 3d). only samples with 10% opc substitute did not present improvement with respect to the compressive strength, for reasons yet to be understood (fig. 3c). the decrease of compressive strength can occur due to modified zeolite in the system. the modified hydrosodalite possesses, the great surface and water absorption and the early strength of hardened cement paste might decrease when zeolite percentage increases (janotka, 1995). bmba samples didn’t develop additional compressive strength or in some cases even experienced a reduction in compressive strength on addition of opc in the blends. in general, with some exceptions, samples lost flexural strength while compressive strength remained the same as for the control sample. geopolymer with bmba gained most of its strength within the first 7 days and later compressive and flexural strength remained the same irrespective on whether additional opc was used or not. pw samples with the opc substitute, similarly to fa samples fa, gained additional compressive and flexural strength. but unlike samples with fa, pw samples experienced an increase in strength (flexural and compressive) with a 5% opc substitute. however higher levels of substitution of opc did not contribute more to the mechanical properties (flexural and compressive strength). nevertheless, pw samples were noted to be the weakest in general, among the materijournal of sustainable architecture and civil engineering 2017/2/19 70 fig. 2 flexural strength of hardened binder: (a) – 0% opc, (b) – 5% opc, (c) – 10% opc, (d) – 15% opc fig. 3 compressive strength of hardened binder, (a) 0% opc, (b) – 5% opc, (c) – 10%, (d) – 15% opc a c b d a c b d 71 journal of sustainable architecture and civil engineering 2017/2/19 als tested, even with the gain of additional compressive and flexural strength due to the opc substitute. exceptions were noted at 7 days for flexural strength with 10 % opc substitute – the only time when pw samples showed larger flexural strength than fa and bmba samples, and at 14 a fig. 4 xrd analysis of hardened binder. (a) fly ash; (b) biomass bottom ash; (c) alf3 production waste (silicagel) days with 5 % opc substitute (fig. 2c), where pw samples were stronger than bmba samples (fig. 2b). separate hardened material samples without aggregate were prepared in order to determine the chemical composition of the binder through xrd analysis. two compositions of each raw material were selected to be tested – without opc (control) and with 15% opc substitute (the maximum substitute in this experiment) to see what difference additional opc contributes to, with respect to the chemical composition in hardened samples. samples with fa and 15% opc additive resulted in the largest gain in compressive and flexural strengths. xrd analysis of the binder showed that additional opc formed c-s-h, which should have contributed to strength development, because it is the primary binding agent in opc concrete (fig. 4a). despite c-s-h formation in hardened binder samples of bmba, concrete samples didn’t gain strength in most of the cases. this phenomenon could be explained through the formation of b c notes: z – sodium zeolite (31-1271); mmullite (84-1205), a – alite (13-272), k – calcium silicate hydrate (33–306), q – quartz (78–1252), ca – portlandite (44-1481), cc – calcite (81-306), c – fluorite (2-1203), n – villiaumite (36–1455, d – larnite (33-302). journal of sustainable architecture and civil engineering 2017/2/19 72 portlandite (ca(oh)2) – the portlandite peaks in the xrd showed the presence of this compound (fig. 4b). this is a relatively weak compound and doesn’t contribute to strength development. it is possible that the larger quantity of cao (48.98%) contributed, to this and that there was not enough sio2 to react. bmba contains only 22.39 % of sio2, while fa contains 49.47%. despite the fact that pw mortar samples were significantly the weakest, just like fa samples pw samples gained additional strength. the xrd analysis of the binder revealed the additional formation of zeolites and c-s-h gel in the system (fig. 4c). the raw material consists mainly of amorphous sio2 (over 70%) and only a fraction of cao (0.42%). according to the results obtained, it can be concluded that opc can be effectively used in geopolymer concrete as additive to increase the mechanical properties of concrete, whilst noting specific issues. the following observations are presented: _ part of the raw materials used for geopolymer concrete could be substituted with opc. the presence of opc increases the flexural and compressive strength. the biggest strength gain was observed after 28 days with fa samples: geopolymer concrete samples reached 29.67 mpa compressive strength and those with 15% additive of opc increased strength up to 50.99 mpa. _ samples with 5% opc additive gained strength more rapidly: after 14 days, 98% of its final strength was reached, while samples without opc reached only 61%. _ the decrease in compressive strength could be caused by the formation of modified zeolite, which, according to literature, increases water absorption. _ analysis of the chemical composition revealed that opc forms c-s-h gel – the primary binder in ordinary concrete. in pw samples, additional opc resulted in the formation of zeolites. _ if raw material has relatively small amount of sio2 and contains a lot of cao, which is often the case with type c fly ash, the addition of opc can result in a decrease in strength in the sample, because of the formation (ca(oh)2). in general, the research indicated that out of the three industrial by-products considered, the fa performed significantly better. while the geopolymer binder performed satisfactorily, the addition of opc as a partial replacement of geopolymer binder resulted in significant increase in mechanical properties of the material. conclusions abdulkareem, o. a. et al. effects of elevated temperatures on the thermal behavior and mechanical performance of fly ash geopolymer paste, mortar and lightweight concrete. construction and building materials, 2014; 50: 377–87. https://doi. org/10.1016/j.conbuildmat.2013.09.047 ariffin, m.a.m. et al. sulfuric acid resistance of blended ash geopolymer concrete. construction and building materials, 2013; 43: 80–86. https://doi. org/10.1016/j.conbuildmat.2013.01.018 pornnapa kasemsiri b, prinya chindaprasirt c garcía-lodeiro, fernández-jiménez i., a., palomo a. variation in hybrid cements over time. alkaline activation of fly ash-portland cement blends. cement and concrete research, 2013; 52: 112–22. https://doi.org/10.1016/j.cemconres.2013.03.022 garcía-lodeiro, inés, maltseva o., palomo a., fernández-jiménez a. cimenturi hibride alcaline. partea i: fundamente. revista romana de materiale/ romanian journal of materials, 2012.; 42(4): 330–35. janotka i, krajci l. the properties of mortar using blends with portland cement clinker, zeolite tuff and gypsum. ceramics, 1995; 39:105-1. yip, c. k., lukey g.c., provis j. l., van deventer j. s. j. effect of calcium silicate sources on geopolymerisation. cement and concrete research, 2008; 38(4): 554–64. https://doi.org/10.1016/j.cemconres.2007.11.001 nath, p., sarker p.k. use of opc to improve setting and early strength properties of low calcium fly ash geopolymer concrete cured at room temreferences 73 journal of sustainable architecture and civil engineering 2017/2/19 perature. cement and concrete composites, 2015; 55: 205–214. https://doi.org/10.1016/j.cemconcomp.2014.08.008 nath, s k, mukherjee s., maitra s., and kumar s. ambient and elevated temperature geopolymerization behaviour of class f fly ash ambient and elevated temperature geopolymerization behaviour of class f fly ash. transactions of the indian ceramic society, 2014; 5456(march): 37–41. pangdaeng s., phoo-ngernkham t., sata, v., & chindaprasirt p. influence of curing conditions on properties of high calcium fly ash geopolymer containing portland cement as additive. materials & design, 2014; 53: 269–274. https://doi.org/10.1016/j. matdes.2013.07.018 posi p. et al. pressed lightweight fly ash-opc geopolymer concrete containing recycled lightweight concrete aggregate. construction and building materials, 2016; 127: 450-456. https://doi. org/10.1016/j.conbuildmat.2016.09.105 shinde b.h., kadam k.n. effect of addition of ordinary portland cement on geopolymer concrete with ambient curing. international journal of modern trends in engineering and research, 2016 turner, l.k., collins f.g. carbon dioxide equivalent (co2-e) emissions: a comparison between geopolymer and opc cement concrete. construction and building materials, 2013; 43: 125–30. https:// doi.org/10.1016/j.conbuildmat.2013.01.023 vytautas bocullo phd student kaunas university of technology, faculty of architecture and civil engineering, department of building materials main research area alkali activated and geopolymer concrete address studentų st. 48 lt51367 kaunas, lithuania tel.+37068248654 e-mail: vytautas. bocullo@ktu.edu danutė vaičiukynienė professor student at kaunas university of technology, faculty of architecture and civil engineering, department of building materials main research area zeolites, alkali activated and geopolymer concrete, byproducts of chemical industry address studentų st. 48 lt51367 kaunas, lithuania e-mail: danute. paliubinskaite@ ktu.edu aras kantautas assoc. professor kaunas university of technology, department of сhemical technology main research area building materials, supplementary cementitious materials, zeolite synthesis. address radvilėnų av. 19 lt5025 kaunas, lithuania e-mail: aras.kantautas@ ktu.lt ruben paul borg senior lecturer university of malta main research area concrete, cement bound materials address department of construction & property management, faculty for the built environment, built environment building, room 213, university of malta, msida, msd 2080, malta tel. (+356) 79055680 e-mail: ruben.p.borg@ um.edu.mt charlo briguglio student university of malta main research area concrete address department of construction & property management, faculty for the built environment, built environment building, university of malta, msida, msd 2080, malta about the authors 65 journal of sustainable architecture and civil engineering 2015/3/12 corresponding author: aleksandrakostic85@gmail.com inclusion of ‘green’ principles in the design of pre-school buildings received 2015/06/03 accepted after revision 2015/08/20 journal of sustainable architecture and civil engineering vol. 3 / no. 12 / 2015 pp. 65-74 doi 10.5755/j01.sace.12.3.13023 © kaunas university of technology inclusion of ‘green’ principles in the design of preschool buildings jsace 3/12 http://dx.doi.org/10.5755/j01.sace.12.3.13023 introduction aleksandra kostic, danica stankovic, milan tanic university of nis, faculty of civil engineering and architecture aleksandra medvedeva st. 14, nis, serbia statistical data indicates that educational institutions are in the second place from the aspect of energy consumption in the commercial sector with account just over 11% of total energy used by this sector. a great part of the preschool facilities in serbia dates back to a period of time when there were no ecofriendly thinking in the building design process and construction. research has shown that these are the buildings of older construction, energy inefficient and often dysfunctional with disrupted the parameters of stay comfort. the significant part of built fund is actually neglected and without planed strategic steps for regular keeping and maintenance. this study defines and valorizes concrete steps and methods for environmental, energy-efficient and economic reshaping in accordance with pre-defined standard, which will provide healthier living conditions, reduce the negative effects on the environment and climate changes and achieve significant energy savings. applied functional technical solutions in international pre-school buildings are analyzed in order to identify their positive characteristics and potential. gathered knowledge and foreign practical experiences are used in the process of creating models adaptable to the areas and needs in serbia. the main objective of research is seen in the tendency to determine and emphasize the direction of future green architectural practice in the area of pre-schools institutions’ building design. the basic idea is to initiate the new design activity which imperatively includes concept and principles of green architecture. final results of mentioned process are a well thought out and detailed environmental energy successful green buildings. with their environmental performances, ‘’green’’ buildings of pre-school institutions, as a group of public purpose facilities, in addition to their positive impact on the growth and development of residing children population, directly contribute to the global energy efficiency increase and reduction of harmful impacts on the environment. the realization of the concept of ‘’green’’ in the area of architecture requires the active cooperation of all the factors of the community. keywords: child, ecological reshaping, green principles, model, preschool building. constant growth of the world’s population and increasing urbanization induce intensified pressure of natural resources and endanger the environment thus directly threatening public health, social and economic developments. amongst all other industries, construction industry causes the largest environmental influences. additionally, we are facing serious energy and natural resource shortage, where global climate change is the problem which cannot be ignored (hsieh et al., 2011). at all levels of society, in all spheres of human life and work, there is evident, positive transformation in the direction of changes in energy policy, establishing of the policy for rational use of energy, inclusion of renewable energy sources in buildings, changes in social circles, etc. consequently, over the last two decades the construction industry has made efforts to develop green building journal of sustainable architecture and civil engineering 2015/3/12 66 practices (gluch, 2006). between 2008 and 2012, there was dramatic growth in the percentage of companies which are into green type of building so to achieve lower operating costs (increased to 30% from 17%) and to gain a branding / public relations advantage (increased to 30% from 22%) (leed).this is not the case in developing and transition countries, as well as in serbia. priyanka (2014) says that the ideal “green” project preserves and restores habitat that is vital for sustaining life and becomes a net producer and exporter of resources, materials, energy and water rather than being a net consumer. also adds: “green building is one whose construction and lifetime of operation assure the healthiest possible environment while representing the most efficient and least disruptive use of land, water, energy and resources”. the office of the federal environmental executive defines term “green building” as the practice of (1) increasing the efficiency with which buildings and their sites use energy, water, and materials, and (2) reducing building impacts on human health and the environment, through better siting, design, construction, operation, maintenance, and removal—the complete building life cycle (howe, 2010). in addition, the environmental protection agency (epa) describes: “green building is the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout building’s life-cycle from siting to design, construction, operation, maintenance, renovation and deconstruction (howe, 2010). this practice expands and complements the classical building design concerns of economy, utility, durability, and comfort. building science corporation defines that ‘green building’ is a label for the process of design and construction which aims to produce buildings that are less damaging to the environment—and the people that use them—than most buildings currently built today. it focuses on incremental steps to solve known and measurable problems with ... current practice. fischer (2010) claims that the green building can be characterized as integrated building practice that significantly reduces the environmental footprint of a building in comparison to standard practices. explanations of green building generally concentrate on a certain number of common segments, especially siting, energy, water, materials, waste, and health, and utility that is also threatened as an explicit design element for a kind of green buildings, known as high-performance buildings. because of the significance and the role that pre-school facilities have in the development of children’s personalities, investing in the field of reviving and renewal of existing built fund, and also in construction of new one, is more than justified. therefore, the future architectural practice should be imperatively directed towards providing comfortable, healthy and motivating accommodation within inner and outer environment of preschool buildings through inclusion of green architecture principles. nowadays, green building and architecture in serbia is a modern trend opposite to the period until 2011 when legislation did not even mention green and building in the same sentence; the only thing that was done during that eco-unfriendly period, regarding green building principles, consisted of copying foreign examples and getting familiar with this subject from their experiences. tanic quotes standards that were adopted: in 1967 (definition of maximum heat transfer coefficient), in 1970 (the parameter coefficient k), 1980 (summer treatment regime was introduced into the budget), 1987 (specific heat losses of buildings), 1998 (specifying the methods and manners of calculation) (stankovic, tanic et.al, 2014). we are witnesses of a change in thinking and therefore consequently change in legislation (building law), where a major part in building code has been dedicated to energy efficiency. paragraphs from this section are being applied daily, regularly and this subject occupies big amount of media attention, but still, awareness of people is not on required level. a methodology research was defined for the very purpose of determining the basic principles of green building and transformation methods of already built pre-school facilities into eco-friendly buildings and to determine, adopt and apply the most favorable model of specific measures to preschool facilities in serbia. in order to define new standard in green building the research comprises the analysis of current literature, follows new trends in the field of green building and analyses of completed buildings with high eco properties. also, comparison of the analyzed projects with the methods 67 journal of sustainable architecture and civil engineering 2015/3/12 emphasis on the positive and negative characteristics, energy efficiency and indoor quality parameters plays major part in defining and adoption of new standards. the aforementioned analyzes were done with the aim to form a model with specific measures that will be widely applicable to whole building fund of pre-school facilities built in serbia. main conclusion and final observations are presented at the end of the research work. review of principles of green architecture the term “green building” has been adopted over the world to describe the concept of design, construction, finishing, equipping and using of facilities that is based on the principle of sustainability. principles of green building comprise a systematic and overall understanding of all the environmental impacts that appear throughout the building’s life cycle, and demand to improve the environmental performances throughout each phase of building life cycle. it considers maximum use of renewable and environmentally clean energy sources (solar energy, wind energy, biomass energy, hydro-energy, energy of natural and artificial water flows, water energy, geothermal energy…), conservation and recirculation of water and energy, use of natural and recyclable materials in construction, use of energy-saving materials (insulation, heating systems), use of sustainable technologies (environmentally and economically), design in harmony with nature and opening of the interior towards ambient, establishing a dialogue between buildings and architectural environment with nature (kostic, 2012). environmental protection agency states that green buildings are emerged with the intention to reduce the overall impact of the built environment on human health and natural environment by: _ efficiently using energy, water, and other resources; _ protecting occupant health and improving employee productivity; _ reducing waste, pollution and environmental degradation. according to halliday (2008) and sev (2009) the basic principles and strategies of sustainable development, in the built environment, should encompass environmental, economic and social aspects. basic principles on which ‘’green’’ architecture is based and which are applied to the buildings for pre-school education are viewed through: _ maximum preservation of the natural environment at the site, minimizing the impact to natural areas that may be in function of space for children stay in an outside healthy natural environment; _ energy, water and material efficiency; _ improving the indoor environment of the building of pre-school institution, establishing the conditions that will ensure adequate air temperature, amount of sunlight, air humidity and adequate air circulation, the conditions for a “healthy” building; _ preservation of the wider living environment area (using eco-friendly materials); _ environmentally conscientious maintenance and management of the buildings and its systems. fowler offers ideas and comprehensive guidance on how to implement the sustainable design principles-principles of green design (fowler, 2012). the planned construction should be completely in compliance with the principles of green architecture. these principles are systematized in following table as features that classify building in one of two types. based on the analysis and interpretation of listed features in table 1, each building can be classified in one of two types of buildings. the key problem presents the existing built fund of building constructed during period when there were no norms of environmental and energy-efficient, sustainable architecture, and when people’s awareness of environmental protection was not suffiresults journal of sustainable architecture and civil engineering 2015/3/12 68 ciently developed. this building fund has been identified as non-green building type. in this case, the main priority is directed towards finding eco-effective, quick and cost-effective systems for establishing the connection between principles of environmentally friendly and energy-efficient architecture with existing, inefficient, polluting building fund. in this sense, the revitalization method proved as convenient way to mitigate adverse effects on environment and, as well, to improve the comfort of stay in indoor environment. serbia has the potential to build facilities in accordance with mentioned principles. in particular, great potential is recognized in the sphere of inclusion of renewable sources of energy. the republic of serbia can produce almost half of its energy needs from renewable sources of energy; nevertheless, the annual exhaustion is only 18-20% of its total potential (kostic, 2011). in order to stimulate use of rse and other features of green architecture in serbia, government needs to advance its attitude towards this kind of energy and manners of green design and construction through following activities: simplifying the administration, raising the awareness within population, motivating investors, and forming suitable mechanisms for funding projects concerned with this important issuerse. efficient functional – technical solutions in international pre-school buildings practice this section of research is dedicated to the analysis of foreign practice and emphasizing their positive characteristics and potential. nursery and kindergarten in zaldibar, spain new building nursery and kindergarten in zaldibar, spain was designed by hiribarren-gonzalez and estudio urgari (fig. 1). the project has a total built area of 663.00m2 developed into one-storey building. the building is aimed to be used by children aged between 0-2 and 2-3. the building is based on good thermal insulation (continuity and adequate thickness) incorporated into the construction system, the maximum use of daylight as the best solution for achieving comfortable conditions of stay, use of geothermal heat pumps and solar heat system, use of ecological and recyclable material (the radiate pine wood from local forests). structure of building, roof, partitions and facade are formed from local wooden prefabricated panels. the roof of the building is constructed with proper water proofing, which also continues in ventilated facades, and zinc cladding. it also provides proper ventilation of the floor. the design and layout of windows (windows in the façade at different heights, sizes and colours) have been studied in order to achieve and enable a high degree of natural lighting, increasing solar gains and reducing heating energy consumption. the prefabricated boxes forming the window frames are also designed according to the inclination to control solar radiation. the building facilities are designed to contribute higher degree of energy efficiency. by installation of an under floor heating system, the thermal quality and energy savtable 1 comparison between “green buildings” and “non-green buildings” (samer, 2013) building type green building non-green building energy consumption low high water use and treatment very good good indoor environment quality very good good emissions low high waste management highly efficient efficient building materials environmentally friendly not environmentally friendly project practices sophisticated normal feasibility >5% than threshold threshold 69 journal of sustainable architecture and civil engineering 2015/3/12 ings are improved. energy gained from biomass is used for heating of the building premises and preparation of hot water. these technical solutions and principles of green architecture are done with aim to reduce energy consumption and co2 emissions, and this way, support to the local economy, environmental comfort and especially quality of life of children are ensured. farming kindergarten, vietnam farming kindergarten located in biên hòa, dong nai, vietnam is designed by vo trong nghia (fig. 2). the building is constructed for low-income factory workers’ children, therefore construction budget was quite limited. architects have created a form of a long continuous track with two side operable windows to provide optimal cross ventilation and natural lighting. following energy-saving measures are included: green roof as an insulation, green facade as shading and solar water heating. this way of providing effectiveness of the building and comfortable reside for children for a result has no need for kindergarten to install air conditioners within children’s premises. inclusion of these devices and creating them clearly visible, makes children familiarize themselves with eco-friendly thinking and get educated in terms of sustainability. apart from all mentioned measures that are visible, more important saving method is comprehensively applied in greenery irrigation system that uses recycled wastewater. it has been concluded, by recording and monitoring the building for 10 months, that the building saves 25% of energy and 40% of fresh water compared to baseline building performance, greatly reducing its runfig. 1 nursery and kindergarten in zaldibar, spain, 2013. architectshiribarrengonzalez and estudio urgari (available at http://architizer.com/ projects/new-buildingfor-nursery-andkindergarten-in-zaldibar/) fig. 2 farming kindergarten, vietnam, 2013, vo trong nghia architects (available at http://www. archdaily.com/566580/ farming-kindergarten-votrong-nghia-architects) ning cost. thus, the mixture of local materials (ex. bricks, tiles) and low-tech construction methods also contributes the process of reducing environmental impact as well as promotion of local production. overview of condition of preschool facilities in south-eastern region of serbia research of existing preschool facilities in the city of nis and one part of southern serbia was conducted from 2011 to 2013, as part of the scientific project “revitalization of preschool facilities in serbia: the program and methods of improving environmental, functional and energy qualities”, financed by the serbian ministry of education, science and technological development. analysis of condition of preschool buildings and their facilities from the aspects of type and condition of building envelope, systems of heating, cooling, ventilation, lighting, energy consumptions, the condition of indoor environmental quality includes 32 buildings located in southeastern region of serbia. the collected data are analyzed and systematized. table 2 illustrates four distinctive examples. most of pre-school institutions’ buildings construction fund in serbia is from period of the seventies and eighties when environmental aspects of architecture were not sufficiently present and visible. actions towards recovery and revitalization of this group of public buildings started only since the year 2000. lack of heat and sound insulation, relatively bad daily and artificial lighting, discussion journal of sustainable architecture and civil engineering 2015/3/12 70 absence or existence of inefficient hvac systems, inadequate interior materialization, can be defined as general leading issues and problems in these buildings. general characteristics of these pre-school buildings in serbia are: _ designed solutions that are out of date (obsolete building fund), _ the lower level of construction quality (in a number of pre-school facilities), table 2 characteristics of the four preschool buildings preschool building location year of construction total built area number of floors description of building envelope roof, facade, floors, joinery hvac systems annual consumption of the electric power kindergarten bambi nis, 1978-1981, 2146.20m2, p+1 _ flat roof-thermally insulated; _ façadethermally insulated _ (bricks with fugues d = 12cm _ polystyrene d = 5cm, _ reinforced concrete d = 18cm or clay block d = 12cm;) _ floorswithout thermal insulation (surface finishes parquet floor and ceramic tiles) _ doors and windows -aluminum frames, double glazed _ own boiler room; _ fuel type coal and wood; _ isolated pipelines; _ without automatic heating regulation; _ natural ventilation; _ ac system does not exist 33390.00 kwh kindergarten crvenkapa nis, 1978, 1644.80m2, p+1 _ pitched roof with mineral wool d = 6-8 cm _ façadewithout thermal insulation (façade brick d = 12cm) _ floorswithout thermal insulation (surface finishes parquet floor and ceramic tiles) _ doors and windows -aluminum frames, double glazed _ city heating plant “jug” _ fuel type natural gas and fuel oil _ isolated pipelines _ without automatic heating regulation _ natural ventilation _ ac system does not exist 78083.28 kwh kindergarten cvrcak, nis 1983-1984, 1683.81m2, p+1 _ pitched roof without thermal insulation _ façade-ventilated façade without thermal insulation _ floorswithout thermal insulation surface finish parquet floor and ceramic tiles. _ doors and windows-wooden frames, double glazed _ city heating plant “krivi vir” _ fuel type natural gas and fuel oil _ isolated pipelines _ without automatic heating regulation _ natural ventilation _ ac system does not exist 46560.00 kwh kindergarten slavuj, nis, 1964, 1115.5 m2 p+1 _ pitched roof with thermal insulation d = 10 cm at midlevel construction slab _ façade –with thermal insulation d = 4 -6cm, _ floors without thermal insulation (surface finish vinyl floor tiles, ceramic tiles, parquet floor m, terrazzo floor; _ doors and windows pvc frames, double glazed _ city heating plant _ “krivi vir”, _ the capacity of the installed boiler 120kw, _ fuel type natural gas and fuel oil _ pipelines are not isolated _ without automatic heating regulation _ natural ventilation ac system does not exist 59297.76 kwh 71 journal of sustainable architecture and civil engineering 2015/3/12 _ energy inefficient and often dysfunctional and with disrupted the parameters of stay comfort, _ absence of maintenance measures, and _ worn-out of building hvac systems and their technically inefficient usage. the analysis of building features the analysis of the parameters that define building envelope and services, the spatial, acoustic, light, air and aesthetic comfort in these facilities is shown in the following section. the average age of examined buildings is 31.5 years. some common characteristics can be found in all facilities: free-standing type of facilities, placing on flat terrain, and in most cases they are two-storey buildings (ground floor aimed to be used for kindergarten and first floor for nursery).these buildings have the same or very similar type of building envelope. the finish layer of façades is mainly made of brick plaster (8.5%) and concrete (8.5%). although the building has been built in accordance with building legislations of the time, since then, the policy regarding energy efficiency has been modified several times. overall methods of revitalizing façade layer may differ. therefore, additional layer of insulation could be installed on external walls, if necessary. pitched roofs (83%) are covered with clay elements and smaller number with galvanized plasticized sheet, flat (17%) roofs are mostly ―”sprinkled” with gravel. maintaining of flat roofs on regular basis is a ground rule to avoid bigger problems and damages caused by leaking as result of failure of hydro-insulation on the flat surface of the roof. apart from this technical suggestion, it may be acceptable to re-design existing rooftops and create green-roof construction in the form of open terrace which can be used by children and personnel. external joinery of the building is wooden (67%), aluminum (21.5%) and pvc (21.5%). central heating system is present in most of preschool facilities. a certain number of facilities use individual coal and wood boilers while some buildings use oil boilers and there are preschool buildings that are connected to the district heating system. plumbing, sewage, heating system and other devices should have been replaced more than once, but in the absence of financial support for maintenance, these systems are operating in more or less original arrangement (jevremovic, 2012). heating systems are outdated and inefficient, uneconomical, without isolation of pipelines in unheated parts of the building and without automatic heating regulation. heating and cooling system may be improved by using and designing passive system for heating and cooling in the building (e.g. solar panels can be easily installed on the flat and pitched roof). in terms of ventilation, rooms in these facilities are generally naturally ventilated, unidirectional, applying temperature differences and air flow, in some cases, various appliances are used (stankovic, 2003). factor that partially disrupts air comfort is presence of outdated covering that emits particles and vapors. regarding indoor environment with most buildings, original condition of materialization and equipment is dominating and some noticeable changes in the interior are present in only a few places. refreshment of internal space is present only within the limits of painting the walls and ceiling surfaces from time to time. area and volume of space of group residence rooms is in the specified range. the buildings are designed for a specified capacity of children, but given the situation and lack of accommodation capacity on the state level, it is common case to exceed the design capacity, and so, in this respect, in a portion of these buildings, spatial comfort is partially damaged. correction of this situation is perceived as providing sustainable capacity through construction of new facilities for preschool education or adaptation of existing buildings for other purposes into space reserved for institutionalized children’s education. light comfort of most of the buildings is in good condition especially in terms of achieving light effects, as they have no adverse effects on the performance of children’s daily activities. the disadvantage is evident in the field of energy efficiency since high percentage of incandescent lamps is dominant. it is therefore necessary to take measures to journal of sustainable architecture and civil engineering 2015/3/12 72 eliminate and replace energy inefficient lamps with contemporary energy efficient lights that will not cause any negative effects. the revival of these facilities should significantly also be in their aesthetics. the following has been observed by analysis of the interior of these buildings: general lack of aesthetic elements of comfort, uniformity of space, lack of inspiration and imagination. generally speaking, attractiveness of these facilities is extremely poor. aesthetic comfort can be collected at a significantly higher level by applying modern interior design solutions in general. crucial phases in the process of revitalization of the preschool buildings revitalization can be construed as the process composed of phases and activities, mutually connected operations that happen in established order within certain time interval. rough and approximate display of the stage, through which revitalization, as planned process of improvement of conditions in pre-school facilities is realized and understands the following: _ research and recording of conditions in pre-school facility in sense of testing its organization and functioning; research and recording of conditions in macro-surrounding and pre-school facility (value and significance, condition, architectural integrity and nature of the facility) – observing, measuring, sampling, noting and documenting, interviews, etc.; analysis of the surrounding in which the project of revitalization is realized; _ analysis of researched condition, which includes analysis of obtained research results, tested indicators, measuring, , calculations, etc.; _ estimation of facility’s condition as well as estimation of the factor of environment that acts either as a risk/threat or as an advantage; _ synthesis of findings and determining of revitalization field; _ implementation of solutions into individual projects; _ creation and development of project revitalization; _ project realization. types of possible measures for increasing the efficiency of pre-school facilities are illustrated in the model (fig. 3). fig. 3 measures for increasing the efficiency of preschool buildings the research has shown that existing building fund, including pre-school facilities in serbia, is not in correlation with features of green architecture. the significant portion of these buildings is actually untreated and without planned steps for habitual preservation and servicing. after detailed examination of existing preschool buildings in southeastern region of serbia, a set of practical conclusions 73 journal of sustainable architecture and civil engineering 2015/3/12 solutions for preserving the environment, reducing energy consumption and improving the quality of the stay in pre-school institutions’ buildings can be defined: _ procurement and installation of insulation and replacement of external doors and windows; _ purchase and installation of more efficient equipment and systems for controlling energy consumption, rehabilitation or replacement of the systems for hot water conduits in terms of losseselimination; _ reduce the use of electricity for heating using heating equipment with higher energy efficiency, an energy-efficient equipment for biomass burning, solar collectors, increasing the efficiency with automatic control system installation and the like; _ installation of energy efficient lighting systems; _ other works performing and purchase of equipment that promotes energy efficiency; _ replacement of worn-out, final lining of the indoor environment. implementation of new technologies and efficient hvac systems, existing materials of improved quality and introduction of new environmentally friendly materials and equipment in the area of external and internal environment of preschool facilities, would not only rise comfort of children to a significantly higher development level, but it would also contribute the process of saving environment for future generation. “one of the ways to initiate extensive revitalization of pre-school buildings in these areas, with aim of their sustainable development, is to initiate projects that would firstly define the methodological approach and general principles, and then concrete actions in the implementation buildings’ reconstruction, taking into consideration possibilities to move to renewable energy resources and choice of the most rational forms for use in given circumstances (kostic, 2011).” however, it is necessary to ensure coordination in decision-making at the level of local government in the areas of urban planning, production and consumption of energy in the building management sector, housing and public construction, protection of environment and resources (stankovic, 2010). this paper is realized within the first phase of scientific project of the faculty of civil engineering and architecture of the university of nis “revitalization of preschool facilities in serbia: the program and methods for environmental, functional and energy efficiency improvement” financed by the ministry of education, science and technological development republic of serbia. acknowledgment appleby p. integrated sustainable design of buildings. uk: earthscan; 2011. epa. united states environmental protection agency, green building. [accessed 12 july 2015]. available from internet: http://www.epa.gov/greenbuilding/ pubsabout.htm. halliday s. sustainable construction. london: butterworth heinemann; 2008. howe jc. gerrard m. the law of green buildings: regulatory and legal issues in design, construction, operations, and financing. chicago: american bar association; 2010. fischer e. issue in green building and the federal response: an introduction, congressional research service, 2010. [accessed 08 august 2015]. available from internet: www.crs.gov fowler km. rauch em. sustainable building rating systems summary. pacific northwest national laboratory us department of energy. 2006. [accessed 10 july 2015]. available from internet: http://www.pnl.gov/main/publications/external/ technical_reports/pnnl-15858.pdf jevremovic lj. rethinking the design of kindergartens – evaluation of the existing building stock in serbia in context of its capacity for renewal. (re) writing history, ”ion mincu” university of architecture and urbanism, bucharest, romania, 2012, 406. keeler m. burke b. fundamentals of integrated design for sustainable building. new jersey: john wiley & sons, inc.; 2009. kostic a., stankovic d. the revitalization and sustainable development of kindergartens in serbia: references journal of sustainable architecture and civil engineering 2015/3/12 74 the case of the city of nis. 2nd wta international phd symposium, building materials and building technology to preserve the built heritage, brno, czech republic, 2011, 2 (i), 354-363. kostic a., stanković d., dačić m. ‘green design’ of the preschool facilities. international scientific conference indis 2012, novi sad, serbia, 2012, 844-851. leed. leadership in energy and environmental design. leed buildings. [accessed 15 july 2015]. available from internet: http://leed.usgbc.org/leed.html opoku a., ahmed v. understanding sustainability: a view from intra-organizational leadership within uk construction organizations. international journal of architecture, engineering and construction. 2013; 2(2): 120-130. http://dx.doi.org/10.7492/ ijaec.2013.012 priyanka m. eco friendly construction methods and materials. international conference on current trends in engineering research, iccter 2014, iaetsd, chennai, tamil nadu, 2014, 83-85. samer, m. towards the implementation of the green building concept in agricultural buildings: a literature review. agric eng int: cigr journal, 2013; 15(2): 25-46. sev, a. how can the construction industry contribute to sustainable development? a conceptual framework. sustainable development, 2009; 17(3): 161–173. http://dx.doi.org/10.1002/sd.373 stankovic, d. aspekti vrednovanja načina meterijalizacije i stepena ekonomičnosti u projektovanju matičnih jedinica dečjih ustanova. [the criteria for evaluating the materialization and cost effectiveness in design process of children premises in the preschool environment] zbornik radova gradjevinsko-arhitektonskog fakulteta u nisu, 2003; 19: 53-62. stankovic, d. reconstruction in order to reduce energy consumption-schools and kindergartens in serbia, 10th international multidisciplinary scientific geo-conference & expo sgem, albena, bulgaria, 2010, 2(a), 725-731. stankovic d., tanic m., et. all. revitalization of preschool facilities in serbia. nis: faculty of civil engineering and architecture, university of nis; 2014. about the authors aleksandra kostic phd student university of nis, faculty of civil engineering and architecture, study program architecture main research area architecture of public buildings, revitalization process of preschool facilities address aleksandra medvedeva br. 14, nis, serbia tel. +381 644455264 e-mail: aleksandrakostic85@ gmail.com danica stankovic phd, associate professor university of nis, faculty of civil engineering and architecture, study program architecture main research area architecture of public buildings, revitalization process of public buildings and sustainable architecture, revitalization process of preschool facilities, architecture of preschool buildings address aleksandra medvedeva br. 14, nis, serbia tel. +381 642103072 e-mail: danica.stankovic@gaf. ni.ac.rs milan tanic phd, assistant professor university of nis, faculty of civil engineering and architecture, study program architecture main research area architecture of public buildings, revitalization process of public buildings and sustainable architecture, architecture of school buildings address aleksandra medvedeva br. 14, nis, serbia tel. +381 641148529 e-mail: milan.tanic@gaf.ni.ac.rs 97 journal of sustainable architecture and civil engineering 2016/3/16 corresponding author: art.cn@frederick.ac.cy frankish-venetian cyprus: effects of the renaissance on the ecclesiastical architecture of the island received 2016/09/22 accepted after revision 2016/10/24 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 97-107 doi 10.5755/j01.sace.16.3.16278 © kaunas university of technology frankish-venetian cyprus: effects of the renaissance on the ecclesiastical architecture of the island jsace 3/16 http://dx.doi.org/10.5755/j01.sace.16.3.16278 nasso chrysochou assistant professor, department of architecture, frederick university demetriou hamatsou 13, 1040 nicosia introduction the paper deals with the effects of the renaissance on the orthodox ecclesiastical architecture of the island. even though the latin monuments of the island have been thoroughly researched, there are only sporadic works that deal with the orthodox ecclesiastical architecture of the period. the doctoral thesis of the author in waiting to be published is the only complete work on the subject. the methodology used, involved bibliographic research and to a large degree field research to establish the measurements of all the monuments. cyprus during the late 15th to late 16th century was under venetian rule but the government was more interested in establishing a defensive strategy against the threat of the ottoman empire rather than building the fine renaissance architecture that was realized in italy. however, small morphological details and typologies managed to infiltrate the local architecture. this was done through the import of ideas and designs by venetian architects and engineers who travelled around the colonies or through the use of easily transferable drawings and manuals of architects such as serlio and palladio. perhaps the most important discovery for the cypriot orthodox ecclesiastical edifices is the use of harmonic rules, the venetian foot and proportional ratios used by the renaissance. all these appear in many remote churches whose builders were most likely in conduct with italian drawings and books. the novelty of the work appears in the collection and compilation of a list of all the orthodox churches that were built or were functioning during the late 15th and 16th century on the island. the collection of all their general measurements and the subsequent research and calculations proves that these for the most part, were not arbitrary structures, but followed the then latest design ideas on ratios, as well as the use of venetian measurement systems. keywords: cyprus, ecclesiastical architecture, morphology, renaissance. when studying the effects that the renaissance had on the orthodox ecclesiastical architecture monuments of the period, it appears at first that the transfer of architectural elements from italy to cyprus, was limited. however, small morphological details and typologies did manage to infiltrate the local architecture. what these features were and how this was achieved remains unexploited. also the paper introduces a list of all the orthodox ecclesiastical edifices on the island during the venetian rule and explores the ratios and dimensions used to arrive at some concluding factors. the frankish domination of the island of cyprus begun in 1191 when cyprus came under the possession of the frankish king, guy de lusignan, who, having lost his kingdom of jerusalem, was seeking a new dominion. during latin rule of cyprus, the catholic church tried to establish journal of sustainable architecture and civil engineering 2016/3/16 98 itself as the dominant religious ruler on the island, diminishing the power of the orthodox one (papadopoulos, 1995) while it immediately tried to establish itself by building majestic gothic cathedrals in all the major cities. it also invited many latin monastic orders to cyprus in order to build grand monasteries all over the island, the remains of which still inspire awe today (gill, 1977, enlart, 1987). however, after the long cohabitation of the catholic latins with the orthodox greeks, they developed a spirit of cultural exchange, which resulted in the coming together of the two communities. the initial repression of the orthodox church by the pontifical catholics gradually subsided, as the penetration of the greek language and greek cypriots, in the circles of the ruling class of the frankish kingdom, contributed to further interaction between the two communities. the involvement of venice in the policies of cyprus begun long before 1468, the year when the last frankish king of cyprus, james ii married the venetian noblewoman catherine cornaro (hill, 1948, jacoby 1977, hunt and hunt, 1989, arbel, 1993, hunt and hunt, 1995, coureas, 2000). the venetian government, rather than implementing an aggressive religious policy against the orthodox church, was more interested in the economic benefits to be derived from the island as well as establishing a defensive strategy against the pressures of the ottoman empire (grivaud, excerpta cypria 1990, arbel 2000). thus, the main religious works in the cities and villages comprised of mainly restoring existing latin and orthodox churches and monasteries, especially after the devastating earthquake of 1491 (grivaud, 1990). on the contrary, there was a flurry of building activity in the troodos mountains with the building of numerous wood roofed churches which belonged to small monasteries, built in many cases by noble latin donors who embraced orthodoxy or couples of mixed religion. (stylianou and stylianou 1960, stylianou,1985). in order to study the various orthodox ecclesiastical monuments and define them historically to the period of the 15th and 16th centuries, it was important to first research the bibliography in order to draw a list of all the churches that fell under this category. the bibliographical research was aided and verified by field analysis and documentation. thus, both the general church plan and a section were documented, followed by full photographic documentation conducted in the field. this allowed an in-depth comparison of the churches themselves but also a comparison with venetian churches in venice itself. this was again achieved both through bibliographic research as well as by an onsite visit to the “serenissima”, to try and draw comparisons and parallels. methods results and discussion typology at the beginning of the latin rule of the island, orthodox ecclesiastical architecture retained its typology, which was still strongly embedded in the byzantine tradition. only gradually did it assimilate some western architectural morphological elements, thus creating the so-called franco-byzantine style, which is a blend of byzantine, frankish and later, to a lesser extent, renaissance elements. by the end of the latin period, at least some western elements permeated both the typology and the structural identity of orthodox ecclesiastical architecture. in the isolated cases of urban monumental orthodox ecclesiastical architecture the typology, integrity of the structure and the precision of western morphological elements, indicate the presence of western workshops, probably the same ones, which were responsible for the construction of the corresponding latin ecclesiastical edifices (papacostas, 2014, olympios, 2014, plagniieux and soulard, 2006). in the many provincial monuments of the latin period, the byzantine compact cross-in-square type, popular in the 12th century, continued to be used but more sporadically, until the 16th century in such churches as that of st. mammas in dali (14th century) and the church of panagia tou sinti paphos (16th century). eleni prokopiou in her published dissertation (2007) has studied the typology and its use in cypriot monuments. (fig.1) gradually a considerable simplification in the preferred type and the prevalence in the 15th-16th century of the single-aisle domed, or barrel-vault, roofed chapel is observed. 99 journal of sustainable architecture and civil engineering 2016/3/16 another type, which appeared in the middle of the latin rule, and which also became more predominant in the 15th-16th century, is that of the double-aisled church. during this period, many orthodox churches acquired a second aisle, for use by the latins for worship or as a burial / devotional chapel. at the early examples this was not equal to the original single aisle nor was there much effort to integrate the new addition to the form of the first chapel. during the venetian period this appears to change, as the double-aisled or twin type of church, with two equal aisles, becomes prevalent. the origin of this type was not some direct transfer but most likely the development of the attempt to enlarge the single-aisled church, with the aim of serving the latin congregation. it might have also been inspired by or was simultaneously developed with similar churches in venetian crete (gratziou, 2010) and other greek islands under venetian rule (kilakou, 1982-1983, triantaphyllοpulοs, 1985) (fig. 2). two-aisled churches are found mostly in the areas of famagusta such as that of panagia avgasida and in troodos, which experienced the greatest ecclesiastical building activity during the venetian period. (papageorgiou, 1975). the three-aisled basilica of the renaissance makes a timid introduction to cyprus, with a few churches (only five out of the thirty-nine) built as three-aisled, fig. 1 church of st mammas, dali (photo by author) fig. 2 two aisled church of st sergious and bacchus famagusta (photo by author) fig. 3 church of st mammas morphou (photo by author) domed structures. they all belong to the period of venetian rule (16th century), perhaps indicating some influence of the predominant renaissance type on the local ecclesiastical architecture.(fig.3) examples of such larger monuments include the church of st. mamas morphou, the oldest monastery church of st nicolas in panagia, the church of missirikou in nicosia, the church of st. marina in the village potamiou, the monastic church of st. neophytos and the wooden roofed and colonnaded church at panagia chrysokourdaliotissa in kourdali. the use of the dome, though associated primarily with byzantine architecture, was also most likely a feature that was encouraged by the venetian renaissance (papacostas, 2014). the aisles were generally separated by columns with ornate, renaissance style capitals that supported arcades which themselves supported the barrel vaults. although the vaulted roofing arose from a structural and material necessity, the external semi-circular form also became particularly popular in renaissance venice. many gothic churches, such as the church of san zaccaria, the miraculous virgin mary (santa maria miracoli), the san felice, st. john chrysostom (san giovanni chrysostomo) of san giovanni battista, and others acquired a new facade with a semi-circular form in front of the triangular pediment of the original gothic church. it is not unlikely, that the journal of sustainable architecture and civil engineering 2016/3/16 100 cypriot monuments mimicked known examples of the renaissance (fig. 4). other typological elements the masonry used in latin ecclesiastical monuments was fine-cut limestone ashlar, while in the orthodox churches it was usually rubble stonework. in the latter examples, dressed stone was used only for the door frames, the cornices and other morphological features. this was not the case with the more important orthodox provincial monuments such as st. nicholas orounta, saint neophytos tsada, st. george teratsioti augorou and others, where the walls were built of cut ashlar following the examples of the grander latin monuments. (fig.5) apart from the choice of materials, there was also a gradual change in the building techniques and structural engineering of ecclesiastical structures during the 15th and 16th centuries. the external blind arches of the middle byzantine period were transferred to the interior, to form burial niches of donors, and were positioned usually in the western end, beyond the arches that support the dome. what once were interfig. 5 church of st nicolaos orounda (photo by author) nal pilasters that supported the domes of the byzantine churches became external buttresses, which supported the thinner masonry walls and in some later examples took on the form of rather squat flying buttress. these were positioned on the longitudinal facades to take the lateral forces of the barrel vault or dome. the byzantine semi-circular barrel vaults gave way to the gothic pointed vault and, in a few examples, the more complex rib vault. such are the church of saint mamas dali and the north aisle of the monastery church of nicosia archangel and the church of saint symeon attached to the cathedral of st george of the greeks, famagusta. from the examples that have been investigated, the rib vaults seem to have been reserved for use in aisles that were added to be used for the latin rites. the roman semi-circular barrel vault reintroduced by the renaissance did not reach cyprus due to the interruption caused by the early ottoman take-over of 1571. in most examples of orthodox churches in the late-latin period, the elaborate diagonal ribs, roof bosses, and other sculptural elements of the gothic churches were transformed into simplified transverse ridge ribs, supported on quadrants and corbels. even though in the earlier examples the vault became externally triangular, this practise was abandoned in the 15th-16th century only to be re-introduced much later in the 18th-19th centuries, often by altering existing barrel vaulted churches to tiled roofs. on the exterior, the byzantine dome and semicircular apse were still used throughout the course of latin rule in orthodox churches, but towards the end of the period, the outer circular drum of the dome became octagonal in shape as the sanctuary apse became externally semi-hexagonal. this new geometric preference probably stemmed from the favourite shape of the romanesque fig. 4 church of st michele in isola, venice (photo by author) 101 journal of sustainable architecture and civil engineering 2016/3/16 architecture of the period of the 10th -12th century and continued to be used both in italy as well as in cyprus until the ottoman take-over of the island (chrysochou, 2003) (fig.6). decorative morphological features cypriot craftsmen, who worked as apprentices next to the french and italian stone mason workshops in the large latin cathedrals and churches, transferred their expertise and knowledge to the rural areas. this is seen in the many morphological features of important edifices, which re-appear in rather humble churches in the most remote parts of the island. with the departure of the first western workshops that were responsible for the large cathedrals, the stone masons continued to copy older morphological details and decorations, unlike the woodcarvers who renewed their designs through material imported in the form of books, prints and engravings. although there is no evidence for the introduction of such books in cyprus there are several examples in greece where western standards often affected the final result. (rigopoulos, 1998). the hood mould with tympana above the doorways and the zigzag torus are both elements of romanesque architecture (11th -12th century), imported to the island by the orders of the benedictines and cistercians, but which were used throughout the latin occupation (enlart, 1902, fernie, 1996, focillon, 1997 tosco, 1999) (fig.7). also other features such as semi-circular stairs, cornice details, such as cyma recta and cyma reverse, elaborate gargoyles, medallions, corner columns and bell towers, were built on the far reaches of the island, transferred there by local stonemason workshops as well as by the cypriot serfs who were forced during the venetian era to work on the construction of the defensive walls of cyprus (arbel, 1995). a typical example of this transfer of sculptural decorations and know-how can be seen in the small church of the monastery of panagia chrysopateritissa in pomos paphos. the northern doorway is protected by a very unusual hood mould ending in spiral volutes on either side instead of the usual horizontal ending. above it is a band of repeated small latin crosses. a fig. 6 st herakledios church politiko (photo by author) fig. 7 southern doorway of panagia tou sindi church near κelokethara (photo by author) similar hood mould appears at the doorway of the refectory of the monastery of bella-pais kyrenia, and above the window on the north elevation of the church of our lady chrysodigitrias (bedestan) in nicosia. a similar form is observed to have been used in crete (gerοla, 1993, μpouras, 2001) and the ionian islands (moschopoulos 1994) which were under venetian rule (fig. 8). fig. 8 bella-pais abbey, refectory doorway (photo by author) journal of sustainable architecture and civil engineering 2016/3/16 102 in the late-latin period the integrity of emulation of smaller detailed renaissance forms betrays local construction, following imported designs and motifs of the period. this is indicated by the unfinished decorated renaissance column capitals and other sculptures, seen in the churches of our lady chrysodigitrias (bedestan) in nicosia, st. mamas morphou, st. mamas potamia, at the incomplete 16th century restoration of the cathedral of saint sophia in nicosia, today the selimiye mosque and elsewhere (fig. 9). the meandering foliage sculptural decorations at the base of the arch of the entrance of the benedictine monastery of panagia stazousa in pyrga (schabel, 2000) are very similar to ones found in venice itself. similarly, the design of the scroll of meandering volutes found fig. 9 the latin church of st mammas potamia (photo by author) fig. 10 the renaissance inspired design of the cornice of the church of st george in potami (photo by author) below the external cornice of the church of st. george potamiou and the church of the cross of missirikou nicosia is recorded in the fourth book on architecture by sebastian serlio, first published in 1537 in venice (byrne, 1982) (fig.10). these influences, however, were always of a small scale. the complex renaissance architectural forms that stemmed from roman antiquity and were prevalent in venice and its colonies at the end of the 15th century never reached the island of cyprus, due to its conquest by the ottomans. in venice, the church of st. george on the island of san giorgio maggiore acquired a new renaissance facade by the venetian architect palladio. similarly, in crete the facade of the monastic church of agia triada tzagarolon in akrotiri was renovated in 1631 with the addition of venetian morphological features. in other greek islands where the venetian period lasted until 1669, they often adopted the tactic of renovating only the facade of older churches using classical renaissance forms. this was done through venetian architects and engineers who travelled around the colonies or through the use of manuals of renaissance architects such as serlio and palladio. such is the example of facade of the church of christ kefalas in candia renovated in 1616 by the venetian surveyors of the kingdom fr. basilicata, who designed marble doorframes and invested the facade with limestone. harmonious proportions and alignments french architects were responsible for introducing the island to the construction expertise of gothic architecture, which required the support of thin external walls flying buttress and the repetition of the grid to accommodate the repeat of formwork and scaffolding. the question of ratio and harmonious proportions (width / length /height) did not seem to concern them. this does not appear so for the venetian period orthodox monuments of cyprus. obviously, some harmonious rules were applied in the construction of orthodox churches, as is shown in the use of specific ratios in floor plans and sections (table 1). 103 journal of sustainable architecture and civil engineering 2016/3/16 village plan ratio addition relationship of height to plan type use of the venetian foot internal dimensions in meters 1. chrysosotiros akaki 1 to 3 single aisled 6.51 χ16.52-to apse 19 2. st george komanon messana 1 to 3 single aisled no 5.32 χ12.92-14.98 3. st george teratsiotis avgorou 1 to 3 single aisled 4.38 χ13.69 4. st mammas sotira 1 to 2 single aisled yes 4.21 χ7.35 5. panagia amoirou apsiou 1 to 3 ( not including the apse single aisled 5.88 χ13.63 to apse 15.5 6. st varvara stavrovouni 1 to 3 single aisled yes 3.8 χ12.10 7. st andronicos polis 1 to 2 width=height single aisled 4.05 χ8.98 to apse 10.62 8. st herakledios politico 1 to 1 single aisled 9. st george agona ormedia 1 to 3 ( total) 1 to 2 single aisled 10. chrysosotiros sotira 1 to 3 single aisled 35.1 χ16 11. panagia podithou galata 1 to 3 width+height /2 single aisled yes 4.16 χ12.3to apse13.63 12. st george potami 1 to 3 single aisled 5.25 χ13.06to apse14.60 13.panagia iamatiki arakapas 1 to 3 single aisled 14. st john the theologian platanistassa 1 to 3 single aisled 4 χ13.84to apse 15.10 15. st john klavdia 1 to 3 single aisled 16. metamorphosis palaichori 1 to 3 width+height /2 single aisled 3.05 χ8.20to apse 9.32 17. stavros agiasmati platanistassa 1 to 3 width+height /2 single aisled no 3.63 χ9.38to apse11.26 (11.45χ5.24 ext.) 18. holy cross pareklissia no single aisled 19. archangel michael delikipos 1 to 2 single aisled 20. st barbara korakou 1 to 3 single aisled 3.65 χ10.28to apse11.55 21. panagia chrysopolitissa larnaca 1 to 3 two aisled 22. panagia podthou platanistassa 1 to 3 width+height /2 single aisled 4.16 χ13.55 23. stavros missirikou nicosia 3 to 2 (approx.) three aisled 11.75 χ7.10to apse 9.22 24. archaengel galata 1 to 3 width+height /2 single aisled 4.5 0χ13.20 25. st barbara peristerona 1 to 2 single aisled 3.66 χ5.72-to apse 6.93 26. st mammas morphou 2 to 3 three aisled yes 11.60χ18.20-to apse 20.60 (13.86χ21.10 ext.) 27. stavros minthis tsada 1 to 3 single aisled 28. st marina frenaros no width=height single aisled yes 5.10 χ11.09 to apse 12.8 29. st nicolas orounda 1 to 2 (approx.) single aisled 4.62 χ8.69 (το 8.91) 30. st marina potamiou 2 to 3 three aisled yes 10.04 χ16.68-to apse 18.42 31. st evlalios lampousa 1 to 3 single aisled yes 12.10 χ4.95 32. panagia of sindi kelokedara 1 to 3 width+height /2 single aisled yes 5.23 χ12.48 33. panagia skouriotissa katydata 1 to 3 single aisled yes 11.01 χ3.66 (5.15χ13.58 ext.) 34. st marina tersephanou 1 to 3 single aisled 4.95 χ14.68 35. holy cross pelendri 3 to 2 three aisled only in width 3.82 χ8.94 36. panagia arediou 1 to 1 width+height /2 single aisled 5.40 χ5.50 37. st ioannis lampadistis kalopanagiotis no single aisled 3.82 χ6.77to apse 710 38. st neophytos tsada 2 to 3 three aisled 39. panagia chrysochourdaliotissa kourdali three aisled 9.04 χ15.32 (to apse) table 1 orthodox churches built or in existence in cyprus during the venetian period journal of sustainable architecture and civil engineering 2016/3/16 104 architects from ancient times until today, tried to find and give divine edifices the symbolism, geometries and proportions that were believed to represent perfection. bruneleschi, palladio, leon battista alberti and many other renaissance architects in their humanistic search, had recorded what they believed were perfect fig. 11 section and plan of monastic church of panagia tou sindi showing the use of harmonic tracings and a ratio in the plan (drawings by n. chrysochou, m. philokyprou, a. pseftodiakos, e. kalliri, e. petropoulou) proportions such as 1:1, 2:3, 3:4, 2:4, 4:9, 9:16 for medium size buildings and 1:3, 3:8 and 1:4 for long buildings. in cyprus, although many churches of the period that have survived are provincial and small, constructed with limited technical knowledge and without exact geometry, it appears that their builders were most knowledgeable, at least, of some of the renaissance architectural rules and harmonious proportions. it is not unlikely that some of these ideas arrived in cyprus through books with western etchings or drawings, which were used by the cypriot builders. the division of the church in three parts obviously has symbolic as well as liturgical functions, thus the ratio of 1: 3 based on alberti’s rules became a popular ratio observed and in most orthodox churches of the venetian period. apart from a few churches, the local master mason was not very concerned about absolute accuracy in the materialized plans but the examples studied ascertain the above theory. twenty-three of the 32 single-aisle churches studied use a plan ratio of 1: 3. also, at least one third made use of the venetian measure of the foot, which proves that local masons had at least some basic level of education. such is the example of the monastery church of panagia tou sinti (chrysochou 2001, 2003) with a plan ratio of 1: 3, and internal dimensions of 5.23 x 12.48 meters (fig 11). these are important as they indicate the use of the venetian foot, which corresponds to 0.3467 meters (dimakopoulos, 1997). thus the church has dimensions of 15 x 36 venetian feet. the other harmonic tracings, which appear in the church indicate an experienced workshop. the interior of the church of the monastery of panagia skouriotissas in katydata, with internal dimensions 11.01x 3.66 meters follows exactly the ratio of 1:3, and externally the use of the venetian foot (5.15x13.58 meters, which equals to 15 x 39 venetian feet). in the church of st. evlalios lambousa kyrenia, the internal proportions of the church of 12.10 x 4.95 meters, also appear to make use of the medieval foot (with only a difference of 3and 10 cm respectively in either dimension). the wooden roofed church of panagia podithou in galata also follows in plan the ratio of 1:3 (except for the apse), and has internal dimensions of 4.17 x 13.55 meters, which equals to 12 x 39 venetian feet. its height is also the sum of the length of the two sides divided by two. the use of the ratio of 1:2 in ecclesiastical architecture of the period was scarce. some examples are saint mamas in sotira, st. andronicus in polis, agios nikolaos in orounta and archangel michael in delikipos. the church plan ratio of 1:2 appears also in the originally gothic church of the virgin stazousa in pyrga. in the case of the addition of a narthex, a common practise during the venetian period, the ratio of 1:1 is found to have been used in most examples. such are the narthexes added to the church of the virgin in arediou, the church of stazousa pyrga (where there is also the use of the venetian measurement), and saint george in angona. in addition, both of the so-called ‘latin chapels’ added to the churches of lampadistis kalopanayiotis and the holy cross at pelendri have a width of 11 venetian feet. in the opposite direction, the master builder adjusted the length of the chapel to the length of the existing church. 105 journal of sustainable architecture and civil engineering 2016/3/16 as a general rule in the few three-aisled basilicas of the period, the ratio of 2: 3 (10:16, 7:11, etc.) is used but with less accuracy. in the church of agios mamas morphou the use of the venetian foot is evident as the external dimensions of 13.86x20.10 meters which are precisely 58x40 venetian feet with the height of the dome at 16.15 meters which is equal to 27 venetian feet (after taking into account the coverage of the original floor with new terrazzo flooring). the height of the dome seems to follow another rule of alberti, pertaining to harmonic ratios: the division of the sum of the length and width by two: as concerns the plan to height ratio of the churches, enough examples appear to follow the renaissance standards, mainly that of the popular harmonic rule of alberti: the division in two of the sum of width and length or the same width to height proportion. the ratio of 1:2:1 can be found in the church of agios andronikos in polis. the wooden roofed church of panagia podithou and the church of the transfiguration in palaichori follow the ratio of plan to height as 1:3:2. (1)11.8 + 20.4 = 32.2: 2 = 16.1 conclusions western influences in ecclesiastical architecture of cyprus are more a result of the evolution of the gothic elements rather than the importation of new ones from venice. few morphological elements were introduced to the island directly from venice and many more were the result of the introduction of venetian military architecture and a few civic buildings, elements of which were carried to orthodox ecclesiastical architecture by local craftsmen. this is not surprising, since in venice itself gothic influence has remained strong, in parallel with the development of the new renaissance art. in terms of the plans, however, and despite the short period of venetian rule in cyprus and the limited technical knowledge of the local masons in geometric drawing, we see that, in less than 100 years, the proportions and the way of construction of orthodox churches appear to have been influenced by italian renaissance architecture. the same question posed as an article title by the late archaeologist arthur hubert stanley megaw about byzantine cyprus (megaw, 1974), “byzantine architecture and painting in cyprus. metropolitan or provincial?” – could be applied to venetian cypriot architecture. and, as in byzantine cyprus, despite all the economic constraints, political and religious repression, and hardships, the cypriot architect of the venetian period has managed to create important examples, if not of a metropolitan scale, then at least of equal interest. arbel b. urban assemblies in frankish and venetian cyprus. cyprus the franks and venice, thirteenth to sixteenth centuries. ashgate; 2000, 203-213. arbel b. η κύπρος υπό ενετική κυριαρχία [cyprus under venetian rule]. θ. παπαδόπουλος (επιμ.) ιστορία της κύπρου. μεσαιωνικόν βασίλειον, ενετοκρατία, τόμ. δ΄ (μέρος α΄). [history of cyprus . medieval kingdom, venetian period] λευκωσία; ίδρυμα αρχιεπισκόπου μακαρίου;1995, 455-536. arbel β. the reign οf caterina cοrner (1473-1489) as a family affair. studi veneziani 26; (1993): 67-85. byrne j.s. renaissance οrnament prints and drawings. new york: the metropolitan museum of arts;1981-1982. cοureas n. cοmmercial relatiοns between lusignan cyprus and venetian crete in the periοd 13001362. επετηρίδα κέντρου επιστημονικών ερευνών 26; (2000): 141-155. enlart c. l΄ art gothic et la renaissance en chypre. [gothic art and the renaissance in cyprus] i,ii. paris: 1899. english translation: d. hunt, gothic art and the reinassance in cyprus, london 1987. i would like to primarily thank mrs mary chamberlain for her aid in data collection. also i would like to thank the department of antiquities cyprus, for all their help in allowing research in their archives and their library, the library staff of the archaeological research unit of the university of cyprus, as well as the library staff of the makarios iii foundation, archbishopric of cyprus. acknowledgment references journal of sustainable architecture and civil engineering 2016/3/16 106 enlart c. manuel d’archeologie franc̜aise depuis les temps mérovingiens jusqu’à la renaissance. [manual of french archeology from the times of the merovingian to the renaissance] architecture religieuse, paris: alphonse picard et fils éditeurs ; 1902. fernie e. rοmanesque architecture. dictionary of art 26 (1996): 568-594. focillon h. art of the west. romanesque: architecture, sculpture, painting, ed. r.toman, köln: hf ullmann; 1997. gerοla g. βενετικά μνημεία της κρήτης (εκκλησίες). [venetian monuments of krete (churches)] μτφ. στ.γ. σπανάκης, κρήτη: σύνδεσμος δήμων και κοινοτήτων κρήτης; 1993. gill j. the tribulatiοns οf the greek church in cyprus 1196-c.1280. byzantinische forschungen,1977; 5: 73-93. griνaud g. sur quelques cοntradictiοns de l’administratiοn venitienne à chypre (1473-1570) [on some of the cοntradictiοns of the administratiοn of venice in cyprus (1473-1570)], θησαυρίσματα, 1990; 20: 190. hill g. a history of cyprus. vol.iii. cambridge: cambridge university press; 1948. hunt d. και i. caterina cοrnarο, queen οf cyprus. αικατερίνη κορνάρο, η τελευταία βασίλισσα της κύπρου (1473-1489), κατάλογος έκθεσης στην πύλη αμμοχώστου λευκωσίας (18.9-16.10.1995), λευκωσία; 1995. hunt d. και i. katerina cornaro, queen of cyprus, london; 1989. jacοby d. citοyens, sujets et prοtégés de venise et de gênes en chypre du xiiie an xve siècle [citizens, subjects and protégés of venice and genoa in 13th to 15th c. cyprus]. byzantinische forschungen 1977; 5: 159-188. megaw a.h.s. byzantine architecture and decoration in cyprus: metropolitan or provincial?. dumbarton oaks papers, 1974; 28: 57-88. olympios m. st george of the greeks and its legacy: a facet of urban greek church architecture in lusignan cyprus, mediterranean nexus.1100-1700. conflict, influence and inspiration in the mediterranean area, ed. co. e. chayes, famagusta art and architecture vol.1, ed. a.w.carr, brepol publishers: 2014, 143-202. papacostas t. a gothic basilica in the renaissance: st george of the greeks at famagusta, mediterranean nexus. 1100-1700. conflict, influence and inspiration in the mediterranean area, ed. e. chayes, famagusta art and architecture vol.1, ed. a.w.carr, brepol publishers: 2014, 348-435. papadopoulos th. η εκκλησία της κύπρου κατά την περίοδο της φραγκοκρατίας, κυριαρχία [the church of cyprus under frankish rule]. θ. παπαδόπουλος (επιμ.) ιστορία της κύπρου. μεσαιωνικόν βασίλειον, ενετοκρατία, history of cyprus . medieval kingdom, venetian period] τόμ. δ΄ (μέρος α΄). λευκωσία; ίδρυμα αρχιεπισκόπου μακαρίου;1995, 543-665. plagniieux ph.soulard, th. l’architecture religieuse [religious architecture]in j.-b. de vaivre, ph. plagnieux (éd.), l’art gothique en chypre [gothic art in cyprus](mémoires de l’académie des inscriptions et belles-lettres, t. xxxiv), paris, 2006: la cathédrale saint-georges-des-grecs de famagouste, 286-296. schabel c. frankish pyrgοs and the cistercians, επιστημονική επετηρίς τμήματος αρχαιοτήτων κύπρου 2000: 353. stylianou a. and j. donors and dedicatory inscriptions, supplicants and supplications in the painted churches of cyprus. jahrbuch der österreichischen gesellschaft,1960; (9): 97-128. stylianou a. and stylianou j. the painted churches of cyprus–treasures of byzantine art. london; 1985. tosco c. romanico. enciclopedia dell ‘ arte mediaeval, 1999; (x) [encyclopedia of medieval art]: 171181. triantaphyllοpulοs d. die nachbyzantinische wandmalerei auf kerkyra und den anderen ionischen inseln, i, münchen; [the late byzantine wall paintings in kerkyra and the other ionian islands] 1985. γκράτζιου ο. η κρήτη στην ύστερη μεσαιωνική εποχή. η μαρτυρία της εκκλησιαστικής αρχιτεκτονικής. 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(ανέκδοτη διδακτορική διατριβή). about the author nasso chrysochou assistant professor frederick university. school of engineering, dept. of architecture main research area venetian period orthodox ecclesiastical and monastic architecture, cypriot vernacular architecture, conservation of historic buildings and monuments. address demetriou hamatsou 13, 1040 nicosia, cyprus tel. 22394394 ext. 45115 e-mail: art.cn@frederick.ac.cy 17 journal of sustainable architecture and civil engineering 2017/4/21 *corresponding author: edita.riaubiene@vgtu.lt sustainability of heritage preservation in academic education of architects in lithuania received 2017/10/01 accepted after revision 2017/12/20 journal of sustainable architecture and civil engineering vol. 4 / no. 21 / 2017 pp. 17-22 doi 10.5755/j01.sace.21.4.19178 © kaunas university of technology sustainability of heritage preservation in academic education of architects in lithuania jsace 4/21 http://dx.doi.org/10.5755/j01.sace.21.4.19178 jūratė jurevičienė, edita riaubienė*, dalius vrubliauskas vilnius gediminas technical university, faculty of architecture, department of architectural fundamentals, theory and arts, traku str. 1, vilnius, lt01132 lithuania research of urgent problems and new aspects of contemporary tendencies in architect education of the preservation of cultural heritage in lithuania has been carried out by the team of department of architectural fundamentals, theory and arts, vilnius gediminas technical university. within the framework of the “sustainable rehabilitation of the historic towns in europe” (sure), project funded by eu with the collaboration among the polish, italian, spanish and lithuanian counterparts, vilnius team has performed the research on the problems in emerging tendencies in the highest education on the preservation of the cultural heritage in lithuania. the questionnaires for the opinion pooling were sent to the selected threefold type of the recipients: educational-scientific, public-state, and privateprofessional (best practices handbook, 2017). the research of enquire reflected devastating effect of recent processes of urban planning in lithuania in the immovable cultural heritage area: neglect of cultural landscape value in urban planning of cities, concern of identity loss and negative impact of globalization, lack of proper maintenance and use of historic buildings. contrary to these revealed problems plea of recent international strategic documents emphasizes variety of ways of contribution of historic areas in bettering of urban life. lack of ecological approach in urban heritage planning, tension between contents of academic programs and official aims of strategic documents ratified by the state, difference in expectations of theoreticians and practicing urban planners were revealed by the results of completed research. the differences in attitudes of academicians and professionals, i.e. inadequate reflection of urban heritage in urban planning processes, shortcomings in integrating of local communities into preservation processes and academic education of architects were clearly stated. variety of important issues in relation with protection of cultural heritage and sustainability was unveiled in academic education of architects in lithuania. provided questionnaires and collected results of the answers, after the completed analysis of the education programs and expert survey disclosed the shortage of ecological knowledge in the field of cultural heritage protection. considering revealed problems and needs integration of sustainability and urban heritage preservation should be proposed as one of major target for the improvement of existing educational system of architects in lithuania. primarily targets to be hit by the alteration of the situation would be the reduction of the lack of ecological approach in urban heritage planning, diminished tension between contents of academic programs and official aims of strategic documents ratified by state and lowered difference in expectations among the theoreticians and practicing urban planners. keywords: architect education, expert survey, sustainability, urban heritage preservation. journal of sustainable architecture and civil engineering 2017/4/21 18 contemporary urban development in lithuania is often associated with disregard for urban cultural heritage. many aspects of these negative phenomena could be related with existing system of architect education; however, no systematic research was accomplished from this point of view during the last decades. research of the problems of heritage protection and architects’ education has been carried out by the team of department of architectural fundamentals, theory and arts of vilnius gediminas technical university. substantial number of urgent aspects of contemporary tendencies in architect education in relation with preservation of cultural heritage were revealed. the research team focused on experience and determinants distinctive for lithuania in contemporary period. the major aim of the research was to generalize the results of expert valuation, and by naming the key problems of architects’ education, and to propose the structure and the contents of new master program framework. the investigation covered two aspects: critical analysis of existing problems of urban cultural heritage preservation in lithuania and diagnose of the teaching system status. the conclusions of overall research were achieved in comparative assessment of the results of both analyses. after final evaluation of basic problems in practice of urban heritage protection and academic education the proposals for new master program were drafted. the questionnaires for the opinion pooling were sent to 50 recipients. the replies were received from the 25 and completed questionnaires were received from 18 respondents. the answers of the respondents revealed basic similarities in evaluation of practical problems of heritage protection and system of education. critical evaluation of current status and expectations in education of architects were highlighted. difference appeared mostly in presented expectations of the theoreticians and of the practicing urban planners. obtained data were used in feasibility study to propose the optimal program of academic architecture master studies. introduction the study is based largely on the data of the expert survey. of particular importance was the establishment of the expedient questionnaire. the structure of questionnaire corresponds to two principal parts. one is dealing with actual situation, asking respondents about the issues and problems related to heritage protection and revitalization of historical towns that are taught on architectural studies, what qualifications architects have in the field, to characterize the general approach to heritage protection, tell the positive and negative remarks on current education of architects in the field. the second part of questions mostly explained the provisions and expectations of the future architecture study program in heritage protection and revitalization of historical towns. the respondents were asked to list and describe the courses, characterize the form and the scope of contact with practice in the curricula, to present the alumnus profile in sustainable urban regeneration, to describe the curriculum content and structure, to present a proposal for a model curriculum in the field of heritage protection and revitalization of historical towns. in order to clarify the situation as closely as possible this two-part questionnaire was addressed to three groups of respondents: educational-scientific (academic), public-state (administrative), and private-professional (architectural practitioners). the obtained data was analyzed, grouped, summarized and abstracted. the results of the survey were compared among the respondents in each group and among all the three groups. finally, holistic evaluation of the experts’ survey with legal contemporary requirements for urban preservation was performed. the generalized results of the survey were synthesized to achieve the findings of the study. methods discussion and results the comparison of international and national legal documents revealed similarity of concept and declared principles of sustainable development. contemporary international strategic documents on sustainable development and preservation of cultural heritage emphasize variety of ways of contribution in bettering of urban life in historic areas (policy document…, 2015). however, mech19 journal of sustainable architecture and civil engineering 2017/4/21 anism of their implementation, responsibility of participants, role of local inhabitants and communities in urban development and heritage protection are still indeterminate in lithuanian legal system. inadequacy and contradictions of legal national requirements are more than evident. architecture education context in lithuania is rather homogeneous. currently in lithuania three schools educate architects (vilnius gediminas technical university, kaunas university of technology and the vilnius academy of arts), but the content of all architecture study programs mainly based on the directive 2013/55/eu of the european parliament and of the council (directive…, 2013), and the curriculum complies with article 46 of directive and the 11 points for architect’s qualification. it is important to mention, that the essence of the 11 points for architect qualification haven’t been revised since 1985, and the concept of sustainability was poorly actualized there. the revised charter of architectural education (charter…, 2011) expanded the competence of the architect with „the awareness of responsibilities toward human, social, cultural, urban, architectural, and environmental values, as well as architectural heritage and adequate knowledge of the means of achieving ecologically responsible design and environmental conservation and rehabilitation”. the demand for professionals in urban reconstruction, regeneration, revitalization was obvious in lithuania since 1960, but despite the obvious need, the specialists with great competence in this field were not educated. after the survey of the content of architecture study programs in lithuania that mostly have the goal to educate the universal creative architect who is able to create architectural designs, the provided knowledge, competencies and skills very poorly meet the special requirement of the professional of heritage preservation and urban revitalization. provided inquiry and collected results of the answers to the questionnaires on the education programs by the country universities and selected practicing professionals reflected need of cohesive approach to the overall heritage values of historic urban environment. if property is owned by the state or municipality requirements for conducting architectural design are restricted by the variety of national laws: law for public purchase, law on protection of immovable cultural properties, law on construction, law on spatial planning, and their amendments are proposed and approved very often. these basic documents should be implemented by huge number of different bylaws; however, no legal requirements establishing obligation of holistic (complex) investigations and survey of cultural heritage are still not determined as obligatory (republic…, 2017). contemporary legal regulation of heritage protection in lithuania is not enough effective as it was revealed by accomplished inquiry. this situation could be explained as rooted in two huge shortages of existing laws: disregard of holistic scientific research in heritage protection and formal approach to participation of local communities. the opinion of the respondents could be accepted as symptomatic because the majority of them are the researchers of cultural heritage and experienced practicians having good knowledge of contemporary problems in the field of heritage protection. existing licensing system in the field of cultural heritage protection in lithuania is based upon variety of requirement for applicant, but almost every architect with 3 years of practical experience of architectural design work is able to obtain this license if his practical work was related with a heritage site or structure. procedure of licensing is determined as complicated, however observance of preservation of architectural value and estimation to authenticity to heritage do not play enough important roles for possibility to obtain the license (lr kultūros…, 2016). possibilities to work in the field of urban heritage administration and management are limited. despite of these difficulties the main competencies of graduates, according the opinion of experts, should be in constant perfection and improvement of qualification. providing excellence of heritage preservation and urban regeneration, the theoretical knowledge and practice must be combined. the master study program rehabilitation of the historic towns should be interdisciplinary and comprise various and diverse aspects of urban heritage preservation. the distributed and lately re-monitored questionnaire draw down the tendency, in the major amount journal of sustainable architecture and civil engineering 2017/4/21 20 of responses, on the nature and specifics of the education of master architects. in the field of qualifications and skills required for the successful work with heritage protection and urban rehabilitation it had shown the necessity to provide comprehensive excellence for education in heritage preservation and urban regeneration, with obligatory to combine theoretical knowledge and practice. architectural master studies on the mentioned above range of education subjects might be treated less than the weak ones without multidisciplinary way of setting up the range of the teaching modules on 1) exploring the understanding and identification of cultural values, 2) deepen essential knowledge on the legislation system in the preservation of cultural heritage, 3) involvement of the societal dimension as end user while trying to ensure the sustainable quality of the preservation projects. the same need was expressed to recover the forgotten in the country knowledge and crafts of the historic tradition in the art of construction, application of the modern technologies in preservation of material authenticity of historic structures and major methods of contemporary technical preservation of heritage. the urban dimension in foreseen curricula, as it was stated by the number of the responders, is obviously lacking the abilities of the specialists to understand urban and social context of urban structures or smaller in scale, but densely build up sites and importance of the dialog between the participating parties, as the major trend in preservation of the cultural heritage of the 21st century. what concerns the teaching specifics about the problematic related to the protection of heritage and revitalization in the light of the desirable qualifications to be achieved by the master students, the following scope of aspects had been accentuated by the responders: 1) to deepen the abilities allowing to understand urban and social context of structure or site under the analysis, 2) development of ability to assess main features of cultural values, to reveal main threats to cultural value and scientific methods to evaluate them, 3) to explore wider the range of abilities of the assessment of the area from the architectural, spatial, functional, technical and social points of view, 4) to apply the planning and design regulations to historic cities, principles of sustainable development in the process of urban revitalization, to analyze the heritage research data and to understand the historic formation/development peculiarities of historical urban structures. from the point of the general approach to heritage protection and revitalization of historical cities, which should be taught at the faculties of architecture with in the master studies, responders pointed out the idea of the increased respect towards the cultural heritage, while planning, using it at present and maintain it safeguarded for the future generations. the ways of executing that would be various, according to the responders, but always based on open and thorough discussion between the decision makers, stakeholders and politicians, professionals-practitioners and scientists, and receivers of the results local communities of society (council of…; faro, 2005). it was noted by the responders, that in order to achieve that contemporary and liberal approach to heritage preservation: 1) while aiming to harmonize them, to follow the problematic way of studying, by presenting the various viewpoints, enabling pluralistic attitude, positive and critical, 2) to strive for the concord of the desire and will to preserve heritage values and adapt heritage to contemporary needs and requirements, 3) to pursue for the harmonization of contradictions of preservation and development, by the sustainable attitude. the insights of the experts can be summarized by this quotation: “the revival of the historic city must be oriented to the social and human dimensions, by applying principles of sustainability” (munoz-vinas, 2005). other positive and negative remarks on current education of architects and their attitude to heritage protection and revitalization of historic cities has been stressed as follows: _ pointing out the current status of the education of architects in the field of the heritage protection, with the present aim, to prepare the wide profile architect, to educate multi-faceted, versatile skilled architect, it was doubtlessly stressed that, specialists’ competencies in heritage preservation and urban revitalization are not sufficiently emphasized. 21 journal of sustainable architecture and civil engineering 2017/4/21 _ architects usually lacking knowledge of history and development of heritage preservation and also the contemporary preservation methods, principles and trends of city regeneration, as well as shortage of knowledge of a holistic approach to the historic environment; _ as one among other reasons for the improper preparation of the architect for urban regeneration activities is the current negative attitude of the architectural community to heritage protection as a fully-fledged architectural activity was underlined and the obvious need to reduce the opposition of new architecture and heritage while bringing together architects, that create the new architecture and who preserve and revitalize the historic architecture was stressed. _ the overall need to pay much more attention to foster the architect’s empathy for community needs and interests, to shape the deep, flexible and adaptive understanding of the diversity of cultural heritage value was notable in the plea of answers by the responders. the analysis of the architecture education programs in lithuania and expert survey revealed shortage of understanding of sustainable urban development. the need of effective means of integration of urban development and urban heritage preservation should be proposed by contemporary architects’ educational system. the main objective of the expected architecture master study program will be to cultivate and foster the holistic approach of the professional. it means that architect should perceive and understand the urban heritage as the multifaceted phenomenon, having great potential to serve the future society. this indicates that the program should aim for multidisciplinary, linking different aspects, such as historical, spatial, functional, technological, social etc. in this case, the program should maintain the problematic nature, providing the optimal coordination and integration of theoretical teaching and practical training. the tighter relations with challenges of practical experience of urban heritage preservation could help to achieve the educational goals of contemporary architect. many problems highlighted by the respondents could be explained by the basic shortages and contradictions of contemporary legal system: disregard of holistic scientific research in heritage protection and formal approach to participation of local communities. that’s why, beside the development of the architect’s abilities to perceive and assess the cultural value, to understand the urban and social context, to explore the place according different views and aspects, to apply legal regulations, principles of sustainable development and modern heritage preservation technologies, the focus in the study program will be made on the incorporation of the social (communal / societal) aspect in to the educational process. this particular element, the dialog of all the participating parties, as the integral part of the modern life, in the program will provide the possibility to be sure that the solution proposed and anticipated results are matching the range of the needs and expectations of those who will maintain the outcomes of the rehabilitation afterwards. the research carried out revealed the need to have more comprehensive and thorough academic education in the field of sustainable preservation of urban and architectural heritage. it should be not limited to architecture master level studies. the provisions of sustainable urban and architectural design must be introduced already on the bachelor level. conclusions acknowledgment the research was carried out within the framework of the project funded by eu (erasmus+) “sustainable rehabilitation of the historic towns in europe” (sure). we greatly appreciate the lithuanian experts, who participated in the survey and provided the competent response to the questionnaire: d. dijokienė, d. klajumienė, j. glemža, v. petrušonis, p. grecevičius, g. tiškus, v. janušauskaitė, v. kundrotas, e. karalevičienė, r. kepežinskienė, r. kraujalis. special thanks for the project manager d. traškinaitė. journal of sustainable architecture and civil engineering 2017/4/21 22 best practices handbook “contemporary realities and needs of sustainable urban rehabilitation”. edited by szmygin, b. lublin university of technology; 2017. charter unesco/uia for architectural education, 2011. available on: www.uia-architectes.org/sites/ default/files/charte-en.pdf council of europe framework convention on the value of cultural heritage for society, faro, 2005. available on: https://rm.coe.int/1680083746 directive 2013/55/eu of the european parliament and of the council of 20 november 2013 amending directive 2005/36/ec on the recognition of professional qualifications and regulation (eu) no 1024/2012 on administrative cooperation through the internal market information system (‘the imi regulation’) text with eea relevance. https://publications.europa.eu/en/publication-detail/-/publication/7508086d-76dc-11e3-b889-01 aa75ed71a1/language-en jurevičienė j., riaubienė e., vrubliauskas d. the teaching of the heritage protection and revitalisation of historic cities at the faculties of architecture in lithuania. in best practices handbook “contemporary realities and needs of sustainable urban rehabilitation”. ed. szmygin, b. lublin university of technology, 2017, 115-136. lr kultūros ministro įsakymas “dėl specialistų vykreferences dančių nekilnojamojo kultūros paveldo taikomuosius mokslinius ardomuosius tyrimus, rengiančių tvarkomųjų paveldosaugos darbų projektus, atliekančių tvarkomuosius paveldosaugos darbus bei vadovaujančių tokiems darbams, atliekančių paveldosaugos ekspertizę, atestavimo taisyklių ir nekilnojamojo kultūros paveldo apsaugos specialisto atestato formos patvirtinimo”, 2016 m. gruodžio 30 d. nr. įv-1012 [description of licensing order of professionals, preparing documents of special planning for protection of cultural heritage. minister of culture and minister of environment”, 30 december 2016 no įv-1012]. available at: http://www.kpd. lt/uploads/veiklos%20sritys/nkpa%20specialistu%20atestavimo%20tvarkos%20apraso%20tvirtinimo%20isakymas.pdf. munoz-vinas, s. contemporary theory of conservation, elsevier, 2005. policy document for the integration of a sustainable development perspective into the processes of the world heritage convention. general assembly of states parties to the world heritage convention at its 20th session (unesco, 2015). republic of lithuania law on protection of immovable cultural heritage. 22 december 1994 no i-733. valid version till 30 september, 2017. available at: http:// www.heritage.lt/t_aktai/istatymai/nkpai_engl.htm . jūratė jurevičienė professor, dr vilnius gediminas technical university, faculty of architecture, department of architectural fundamentals, theory and arts main research area preservation of cultural landscape and architecture address traku str. 1, vilnius, lt01132 lithuania tel. +370 68969345 e-mail: jurate.jureviciene@vgtu.lt edita riaubienė assoc. professor, dr vilnius gediminas technical university, faculty of architecture, department of architectural fundamentals, theory and arts main research area architectural education, architectural heritage address traku str. 1, vilnius, lt01132 lithuania tel. +37061216573 e-mail: edita.riaubiene@vgtu.lt dalius vrubliauskas assoc. professor vilnius gediminas technical university, faculty of architecture, department of architectural fundamentals, theory and arts main research area architectural heritage preservation address traku str. 1, vilnius, lt01132 lithuania tel. +37061812169 e-mail: dalius.vrubliaukas@vgtu.lt about the authors 5 journal of sustainable architecture and civil engineering 2017/3/20 *corresponding author: inga.urbonaite@yahoo.com adapting participatory design tools in design through research (dtr) models to develop sustainable projects in sensitive territories. case analysis received 2017/10/18 accepted after revision 2017/11/21 journal of sustainable architecture and civil engineering vol. 3 / no. 20 / 2017 pp. 5-13 doi 10.5755/j01.sace.20.3.14055 © kaunas university of technology adapting participatory design tools in design through research (dtr) models to develop sustainable projects in sensitive territories. case analysis jsace 3/20 http://dx.doi.org/10.5755/j01.sace.20.3.14055 gerda antanaitytė klaipėda university, faculty of humanities and education sciences, department of philosophy and culturology, s. nėries st. 5, 92227, klaipėda inga urbonaitė-vadoklienė* lcc international university, lcc innovation lab, kretingos g. 36, lt92307 klaipėda, lithuania urban development, or architectural design in fragile (sensitive) territories is always complicated, especially when one considers national, regional, reserve parks, or other territories that have a lot of sociocultural meaning to society, and local communities. existing bureaucratic procedures complicate community involvement into planning process, and creativity manifestation in decision making is vague. the article analyses three design through research project cases developed by authors, which share common goal to improve the quality of the environment using innovative and contemporary solutions, deal with landscape sustainability and local identity issues by involving community into design process. presented samples reveal three different design through research and participatory design models. in each case site planning projects are initiated by different groups, therefore motives for the project implementation differ. that determines the sample of public inclusion, scope of fulfilled research, design solutions and capabilities for sustainability of the project. comparative analysis of these cases summarize strengths and weaknesses of each model and form recommendations for similar territorial development in the future. keywords: sustainable design process, participatory design, sensitive territories, community engagement, urban design, cultural identity. introductioninteraction of anthropogenic and natural processes forms distinctive and unique character of a place, which is identified as genius loci and valued as one of the main aspects of sustainable architecture. on the other hand, urban designers and architects quite often face a challenge to comprehend the identity of a place, by uncovering apparent layers of cultural landscape and articulating their value in actual contemporary architectural forms. every urban development, or architectural design in sensitive territories meets a challenge of prioritization, and the need to find balance between natural landscape, local resources, and sociocultural factors is essential. following strict rules and planning regulations is not always the answer as it sometimes becomes a formal procedure for bureaucrats to ban innovative solutions. such solutions would not only journal of sustainable architecture and civil engineering 2017/3/20 6 improve ecological quality of the territory, but would also be relevant to local communities and cover their needs. instead, quite often the quality of aesthetic design solutions suffers, because a more common approach of imitation is chosen over interpretation of established architectural forms. one of the main reasons for such complicated development in sensitive territories is a lack of proper models of the design process. theory and practice of contemporary urban design pays a lot of attention to community involvement into the design process and the models of design process itself. the concept of sustainable development aims to find consensus among different stakeholders and balance different needs (sobandi and sudarmadji, 2015). public participation is the process by which the public concerns, need and values are incorporated into governmental and corporate decision making (ismaila and saidb, 2015). collaboration theory defines the importance of facilitating participation of multidisciplinary teams and stakeholders (morales, 2013). relation, networking, coordinating, and cooperating is as essential as non-hierarchical relationships among different groups of interests. it is when planning process is understood as developmental continuum and previous strategies are incorporated into the new ones (himmelman, 2002). in lithuania, after implementation of the new law of spatial planning in 2014 (lietuvos, 2013), new rules regarding the coordination of public interest were set. by giving the right of regulation and organization of city planning to municipalities, the public involvement became very relevant. although this law eliminated a lot of problems that existed in the field, some researches argue that legal formulation of the new law has limited public interest representation and serves only to certain groups of interests (lastauskienė and bakštienė, 2015). it seems that public interest is protected only in certain fixed cases which are set by rules without actual possibility to critically and creatively approach the territory planning process. for this reason, it is essential to educate society and form the practice of public involvement through sustainable territory planning models. especially public interest should be protected when dealing with sensitive territories. it is evident that even unsuccessful planning processes or unrealized projects raise public awareness and social self-consciousness, i.e. the society’s ability to concentrate, discuss and influence the governmental institutions, pass the determined decisions and precondition the unexpected course of architectural processes, is established (gudelytė-račienė, 2017). participatory planning model is already widely spread and implemented in various forms around the world (cauchi-santoro, 2016; proli, 2011; shuib et al., 2015; rasoolimanesh et al., 2017; stewart et al., 2004 and many more), however it is still quite a fresh and not recognized practice in lithuania. facilitation of such projects is quite a new phenomenon; especially in lithuanian context, where quite often it becomes a challenge due to lack of human resources and competences. nevertheless, participatory development is the most important approach towards enabling communities to help themselves and sustain efforts in development work (cirtautas, 2011). communities are no longer seen as recipients of development programs; rather, they have become critical stakeholders that have an important role to play in the management of programs and projects in their areas. in this context it is more relevant to talk about territorial and local communities which are in one or another way physically connected to certain territory and might have various, quite often contrary needs and interests (urbonaitė, 2011). traditionally, architects and designers carry all responsibility for the design process, as they deliver final design solutions to approving institutions. the latter are officially responsible for balancing the needs of different stakeholders. however, in reality, lack of their involvement in the development process, complex understanding of territory, and interdisciplinary collaboration is evident. 7 journal of sustainable architecture and civil engineering 2017/3/20 researh methods another important problem is the implementation of design solutions and continuity of the project. sustainable and qualitative result is inherent in communicating, informing and educating related communities and stakeholders. only those parties, who are capable of recognizing the identity, meanings and coded values of a certain sensitive territory, are capable of later taking care of it and feeling connected. q methodology is quite often used to assess the diversity of opinions among the community, produce new themes for a group of people and subsequently be used in improving the quality of developed territory. such approach allows to connect qualitative and quantitative data concerning perceptions, beliefs, attitudes, opinions or viewpoints of different stakeholders (shuib et al., 2015). there are three main operating sides that shape the environment: professionals (architects), institutions (municipality, national parks, nature protection, cultural heritage department etc.) and community. each of the interested parts has its own approach to environmental development, therefore dedicating decision making to one of the parts, disregarding interests and knowledge of the rest of interested groups affect quality of the whole project. the purpose of this study is to identify the effectiveness of particular practical approaches in dealing with participatory design models in sensitive territories of lithuania. methodology and research design case study approach has an emphasis on detailed and relativity based analysis on particular set of conditions, data sets or subjects. the method is open to the variety of disciplines, but relative to our case, qualitative research method is used by contemporary sociologists to examine real-life situations to provide basis for the future development and application of ideas and methods. as defined by researcher robert k. yin, the case study method is an empirical inquiry that investigates a contemporary phenomenon within its real-life context; when the boundaries between phenomenon and context are not clearly evident; and in which multiple sources of evidence are used (yin, 1984). case study method was selected to compare three participatory design projects developed in last three years in sensitive lithuanian territories: creative workshop and architectural competition aimed to create small scale architectural objects reflecting spirit of the place genius loci in curonian spit, unesco world heritage site; feasibility study development for karklė village situated at the seaside regional park; landscape formation and environmental condition improvement project for sablauskiai pond access situated at akmenė district. comparative analysis of these cases summarizes strengths and weaknesses of each model and forms recommendations for similar territorial development in the future. research authors were engaged in mentioned projects as a part of initiating and content creating groups and had opportunity to comprehensively observe and actively engage with the process. structure of the research design consists of three following parts: 1. cases. three participatory design projects developed in last three years in sensitive lithuanian territories; 2. case study variables. two main categories of variables that are compared; 3. data analysis. investigation of interaction between different case study variables and gene rated results. cases project 1. architectural stops in curonian spit the project was initiated by non-governmental organisation architect a. zaviša charity and journal of sustainable architecture and civil engineering 2017/3/20 8 support foundation (in the following paragraphs azf) as an experimental method to design small scale contemporary architecture projects in curonian spit. curonian spit is a highly protected area in lithuanian seaside. the territory is unesco world heritage site and belongs to curonian spit national park. architectural expression of traditional fishermen houses dominates in the site. prevailed imitative approach as the only right or safe way to design in the area and lack of contemporary statement was the main problematic issue raised by the initiator. the main purpose of the project was to involve parties into design process from the first architectural design stage thus provoking discussion and finding common ground for the contemporary approach. selected form of the project was creative workshop and architectural competition where five groups of architects were designing concepts for the bus stops. the project lasted for five months. project 2. karklė atlas the project was initiated by four operating parties: community of karklė village, non-governmental organisation (afore mentioned architect a. zaviša charity and support foundation), klaipėda district municipality and seaside regional park to define guidelines for karklė village public places development. the village belongs to seaside regional park territory and has ethnocultural reserve status. war, political system, urban changes drastically transformed former seaside fisherman village in the past 70 years. territory’s outlasted landscape, demographic, urban structure changes has raised problematic issue to determine contemporary identity of the village by respecting historical cultural and natural layers of the site. the main purpose of the project was to analyse different aspects of the situation and prepare feasibility study for future village development. the project lasted for nine months. project 3. landscape formation and environmental condition improvement project for sablauskiai pond access situated at akmenė district the project was initiated and coordinated by akmenė region municipality. the initial goal was to develop access to sablauskiai pond and improve recreational, ecological and landscape conditions of the beach territory, used by local community. the site is a part of regional natural frame although no strict protection regulations or requirements are determined. nevertheless, the territory is very interesting and sensitive as the pond is artificial and initially was made by digging dabikinė river. it was used as water source for the local cement plants in 1970s. the landscape has already suffered from anthropogenic activity and ecological biodiversity is still very fragile and emerging. the driving force of territory development was a possibility to get european funding for landscape formation and environment conditions improvement. the choice of this financial instrument determined the whole design process model and forms of public involvement as it was clearly set in funding application requirements from the very first stage. the crucial problematic was to balance recreational needs of local community with high ecological requirements of the program. one of the main design process goals was to educate participating parties and provide deeper knowledge about biodiversity and uniqueness of the territory. the project lasted for 9 months. case study variables there are two main categories of variables that are compared in the following research part: _ a. participants. there are four operating participant parties involved in the project development: _ initiators. question problematics and determine purpose of the project; _ coordinators. trigger project establishment, manage the project and its process; _ content creators. participants generating content of the project; 9 journal of sustainable architecture and civil engineering 2017/3/20 _ reflective participants. participants that are directly and indirectly involved in certain stages of the project through giving feedback. b. process. determinates communication, planning and designing models between participants in terms of frequency, duration, involvement roles and responsibilities. aspects of process evaluation: _ form of participatory planning model. indicates interaction schemes between participants; _ direct involvement. indicates frequency and range tools used by coordinator to communicate with project participants; _ indirect involvement. indicates frequency and range of communication tools used by coordinator to reach wider audience that is not directly involved in the project; _ continuity. indicates range of tools and initiating parties for future project continuation. data analysis data analysis is based on the investigation of interaction between different case study variables and generated results. project success is determined by evaluating following priorities: _ project reach. evaluation of direct and indirect engagement into the project process; _ complexity of project management; _ complexity of tools. evaluation of project development model and interaction between participants; _ impact on fragile territory. evaluating the balance of interests, project continuity and the development of the participants’ engagement through the following project stages. comparative data of the cases and case study variables is presented in the table 1. analysis of the data project 1 was initiated by non-governmental organization. project development management and tools were quite new at that time, also high level of indirect involvement due to authoritative participants. architects and scientists involved in the project are well known in their professional fields. the process was widely presented to professionals and national media. we can assume that these features encouraged further project development implementation of winning project initiated by municipality and book publishing initiated by non-governmental organization. development model of project 1 is successful participatory design example and has positive impact on fragile territory in terms of project results acceptance, but lack of project acceptance from local community. project 2 was initiated by two equal parties municipality and community in close cooperation with ngo. during the process content creators were presenting every part of the project to initiators and all reflective participant groups and receiving feedback thus developing the project. due to the process management, involvement and tight cooperation between all participants in all stages of the project, final results were accepted by all involved parties, furthermore, continuity of the project was initiated by municipality, community and ngo. we can assume that development model of project 2 is the most successful participatory design example and has significant impact on fragile territory. project 3 was initiated and continued by municipality. due to strict agenda and non-flexible process management from the municipality, the project has poor dissemination and community involvement. the project is continued by initiative of the municipality. results journal of sustainable architecture and civil engineering 2017/3/20 10 cases project 1 architectural stops in curonian spit project 2 karklė atlas project 3 landscape formation and environmental condition improvement project for sablauskiai pond access situated at akmenė district projects comparison participants in it ia to rs non-governmental organization (azf) community of karklė village; klaipėda district municipality; governmental organisation seaside regional park; non-governmental organization (azf) municipality project 1 was initiated by ngo; project 2 has two content creating parts scientists and architects; project 3 was initiated by municipality c oo rd in at or s non-governmental organization (azf) non-governmental organization (azf) municipality projects 1 and 2 are coordinated by independent expert; project 3 is coordinated by municipality c on te nt c re at or s architects scientists; architects architects; professionals project 1 has one content creating part architects; project 2 has two content creating parts scientists and architects; project 3 has two content creating parts – architects and professionals r efl ec ti ve p ar ti ci pa nt s community; municipality; institutions (forest enterprise, lithuanian road administration, curonian spit national park); scientists (sociologist, nature scientist, historian) community; municipality; institutions (seaside regional park, forest enterprise) community; municipality; authorities (environment protection agency, ministry of environment of the republic of lithuania, apva) project 1 has four reflecting parties; project 2 and 3 have three reflecting parties process p ro je ct d ev el op m en t m od el sequential: ● → ● → ● → ● ● initial design proposal ● design reflected by community ● design reflected by scientists ● final design proposal parallel: ■ → ■ ■ ● → ■ ● ■ ● ▲ → ■ ● ▲ ■ ■ presented / reflected research part ● ● presented / reflected concept part mixed: ● → ■ → ▲ → <> / \ / \ / \ / \ ●→● ■ →■ ▲→▲<>→<> ● community involvement program (cip): presented/ reflected/ approved ■ research stage: presented/ reflected/ approved project 1 has sequential development model where each stage of the project is reflected by different participating party; project 2 has parallel development model where each stage of the project is reflected by all participating parties; table 1 cases comparison table 11 journal of sustainable architecture and civil engineering 2017/3/20 cases project 1 architectural stops in curonian spit project 2 karklė atlas project 3 landscape formation and environmental condition improvement project for sablauskiai pond access situated at akmenė district projects comparison p ro je ct d ev el op m en t m od el all stages of the project are developed by content creating parts (architects). each stage is presented to individual reflective participant group. the feedback obtained from reflective group support the project development in the next stage that will be presented to following reflective participants group ▲▲presented / reflected design proposals part for every part of the project that is made by content creators (scientists and architects) is given feedback from all reflective participant groups (municipality, community and governmental organisation) ▲ design proposal stage: presented/ reflected/ approved <> technical planning stage: presented/ reflected/ approved first of all community involvement program is prepared which sets the rules of community participation in all project stages. every stage is presented, reflected and approved by community, municipality and authorities project 3 has mixed development model where sequential project development plan is set and community involvement program is prepared which allows participating parties to reflect on the project at every stage d ir ec t in vo lv em en t meetings with participants depending on needs meetings with participants depending on needs meetings with participants according the cip program projects 1 and 2 have flexible agenda for meetings, discussions and ability to change programme of the project depending on the process; project 3 has strict program and agenda in di re ct in vo lv em en t updated information on the website dedicated to project development projects exhibition public event with final presentations publications in media published book updated information on the website dedicated to project development public event presenting results publications in media updated information on akmenė region municipality website (official announcements) projects 1 and 2 have wide range communicating tools; project 3 information dissemination is formal and narrow c on ti nu it y implementation of winning project. initiated by municipality publishing of the book. initiated by ngo project area extension. initiated by municipality and ngo preparation of a technical requirements of project implementation. initiated by municipality and ngo development of design proposals preparation of technical task and technical project. initiated by municipality. implementation of design solutions. project 1 is continued by the initiative of municipality; project 2 is continued by initiative of municipality, institution and community; project 3 is continued by municipality journal of sustainable architecture and civil engineering 2017/3/20 12 references analysis has shown that participatory design approach is sufficient for the development of sensitive territories. finding common ground between different interested parts is a complex process which requires debates, understanding and setting right expression tools. thus sufficient timeframe to experience the process profoundly rather than formally is crucial. project 1 was the case of bottom-up initiative where the whole design process was started by an ngo, which, in this case, acted as a community of professional interests. it took time and effort to convince municipality and other authorities to partnership and make further actual steps of project implementation. in such cases, the lack of motivation to bring changes is crucial, especially if it is not fixed in any regulations or formal administrative duties. it is important to set clear participation rules but also leave space for dynamics and spontaneity during the design process. project 3 showed that too strict formulations and process management regulations can diminish the motivation to involve and reflect on the ongoing design process. one of the main aspects of effective participatory design models is the role of competent and independent design process facilitator. the practice of analysed cases showed that municipality can be quite a good project administratorcoordinator, but it should not be forgotten that in reality, municipality is not a neutral stakeholder and must be considered as one of the project participators. moreover, municipalities quite often lack human resources, competences and lack of freedom to facilitate design processes in a creative and innovative way and for this reason neutral professional facilitators should be chosen. architects are the ones that are usually expected to manage and facilitate the process. however, architects’ role is to synthesize complex information and provide design solutions and for this reason they are considered as experts-participants, who cannot stay neutral when their design solutions are questioned or discussed. all three projects have reached the technical design project phase and further research could be held to monitor and track the implementation of proposed solutions. as lithuanian practice shows, design proposals are very often misinterpreted and changed at technical design project stage, especially, when municipalities become responsible for it. for this reason, it is very important that an independent facilitator stays within the project till the very end and makes sure that public interests are protected and sustainable proposals are valid. especially when it requires complex and long term urban design process coordination. discussion and conclusions cauchi-santoro, r. mapping community identity: safeguarding the memories of a city’s downtown core. city, culture and society, 2016; 7: 43-54. https://doi.org/10.1016/j.ccs.2015.12.003 cirtautas, m. visuomenės dalyvavimo urbanistinio planavimo ir projektavimo procesuose realijos ir perspektyvos/ reality and perspectives of public participation in urban planning and design processes. k. šešelgio skaitymai-2011/ k. šešelgis readings-2011. 2011; 3(3): 59-66. cojanua, d. homo localis. interpreting cultural identity as spirit of place. procedia – social and behavioral sciences, 2014; 149: 212-216. https://doi. org/10.1016/j.sbspro.2014.08.219 gudelytė-račienė, i. the role of unrealized projects in development of social consciousness. k. šešelgis’ readings – 2017. 2017; 9(1): 118–126. himmelman, a.t. collaboration for a change. definition, decision-making models, roles, and collaboration process guide. minneapolis: himmelman consulting; 2002. ismaila, w.a.w., saidb, i. integrating the community in urban design and planning of public spaces: a review in malaysian cities. procedia social and behavioral sciences, 2015; 168: 357-364. https://doi. org/10.1016/j.sbspro.2014.10.241 lastauskienė g., bakštienė d. visuomenės interesų apsaugos problema planuojant teritorijas/ public interest protection problem in the spatial planning process, teisė, 2015: 96-70. morales, j.a. sustainable development by means of a collaborative planning framework the case of municipal housing, guatemala city. master thesis of geo-information science and earth observation. enschede, university of twente; 2013. 13 journal of sustainable architecture and civil engineering 2017/3/20 about the authors proli, s. improving an urban sustainability environment through community participation: the case of emilia-romagna region. procedia engineering, 2011; 21: 1118-1123. https://doi.org/10.1016/j.proeng.2011.11.2119 rasoolimanesh, s.m., jaafar, m., ahmad, a.g., barghi, r. community participation in world heritage site conservation and tourism development. 2017. tourism management, 2017; 58: 142-153. https:// doi.org/10.1016/j.tourman.2016.10.016 ramalis sobandi and noviantari sudarmadji. knowledge sharing and stakeholder collaboration practice in solo city planning and development: notes on urban community nurturing processes. procedia social and behavioral sciences, 2015 184: 161 – 170. https://doi.org/10.1016/j.sbspro.2015.05.076 shuib, k. b., hashim, h., nasir, n.a.m. community participation strategies in planning for urban parks. procedia social and behavioral sciences, 2015; 168: 311320. https://doi.org/10.1016/j.sbspro.2014.10.236 stewart, w.p., liebert, d., larkin, k.w. community identities as visions for landscape change. landscape and urban planning, 2004; 69: 315-334. https://doi.org/10.1016/j.landurbplan.2003.07.005 urbonaitė, i. miesto teritorinių bendruomenių įtaka rekreacinių teritorijų formavimui [urban territorial communities and their influence forming urban recreational territories], mokslas – lietuvos ateitis. k. šešelgio skaitymai – 2011 [science – future of lithuania. k. šešelgis readings – 2011], 2011; 3(3): 30-37. lietuvos respublikos teritorijų planavimo įstatymo pakeitimo įstatymas. valstybės žinios, 2013, nr. 763824. yin, r. k., case study research. design and methods, 1984: 23.received: 18 10 2017 gerda antanaitytė project coordinator architect a.zaviša charity and support foundation lecturer klaipėda university, faculty of humanities and education sciences, department of philosophy and culturology main research area phenomenology in architecture, intersection of culture, society and space address turgaus g. 8-14, klaipėda tel. +37061706767 e-mail: antanaityte.gerda@gmail.com inga urbonaitė-vadoklienė director at lcc innovation lab lcc innovation lab, lcc international university main research area public spaces, community involvement, creative thinking, architecture and urban design address kretingos g. 36, klaipėda tel. 862091989 e-mail: inga.urbonaite@yahoo.com 19 journal of sustainable architecture and civil engineering 2017/1/18 *corresponding author: sebong@rocketmail.com factors affecting architectural design for crime in nigeria: role of the architect received 2016/12/11 accepted after revision 2017/02/28 journal of sustainable architecture and civil engineering vol. 1 / no. 18 / 2017 pp. 19-26 doi 10.5755/j01.sace.18.1.17348 © kaunas university of technology factors affecting architectural design for crime in nigeria: role of the architect jsace 1/18 http://dx.doi.org/10.5755/j01.sace.18.1.17348 samuel o. ebong* university of uyo, faculty of environmental studies, department of architecture nwaniba road, uyo, akwa ibom state, nigeria stella n. zubairu, remi e. olagunju federal university of technology, school of environmental technology, department of architecture minna, nigeria introduction it has been acknowledged by researchers and practitioners of crime prevention that design is an important tool that could be used to prevent crime and reduce fear of crime while increasing sense of community. however, the architect faces several challenges in the attempt to address crime prevention issues in his design. this paper assessed the factors that hinder architects in nigeria from addressing issues of crime prevention holistically in their designs. survey research method was adopted for the study. 132 questionnaires were administered to architects in akwa ibom and cross river states of nigeria. 87 properly filled and returned questionnaires were used for the study. percentages and mean score analysis and ranking method were used as the analysis tools. interviews were also carried out with key architects with 12 to 37 years of practice experience. the result revealed the major hindrances to architectural design for crime prevention to include lack of documented examples and no crime prevention requirements in planning and building regulations in nigeria among others. these factors are knowledge related. this suggests that knowledge has a significant and positive effect on architectural design for crime prevention as it helps architects to take good and informed design decisions. it notes that documented examples have three major functions namely, knowledge sharing, knowledge transfer and knowledge preservation. the paper concluded that these factors affect the ability of architects to design against crime because architectural design is knowledge dependent and knowledge driven. it recommended that physical security concepts and crime prevention through environmental design should be made part of formal architectural education training and/or professional continuing development programme in nigeria. keywords: architectural design, crime, crime prevention, factors, security. the global trend of population growth and rapid urbanisation has caused crime to become one of the most serious social problems as crime rates around the world continue to escalate (marzbali et al., 2011). crime creates fear (stafford et al., 2007) which is further intensified by media attention focused on the issue. there is also the perception that law enforcement personnel alone cannot solve the problem as police are unresponsive in many cases or only respond after the crime has taken place. this has drawn attention to the need for partnerships to tackle the crime problem. since crime takes place in the built environment citizens look up to architects also to design secure buildings. creating an environment that is safe is one of the biggest challenges of the 21stcentury (bercovich, 2010). journal of sustainable architecture and civil engineering 2017/1/18 20 crime prevention involves the anticipation, recognition, acknowledgement and appraisal of a crime risk or threat and taking some actions to remove or reduce it (national crime prevention institute, 1986). for crime to be committed the criminal must have a motivated desire; must be criminally skilful, must have the proper tools to commit the crime and must locate a target that provides the opportunity to commit the crime. the aim of crime prevention, therefore, is to protect the target by reducing and/or eliminating criminal opportunity. this is possible by making a potential target of attack unattractive, inaccessible, dangerous and unprofitable to the criminal. in other words, increase the risk and reduce the ease and reward factors. crime prevention relies on the principles of deter, delay, detect and deny – the 4ds of crime prevention (fennelly, 1989; crowe, 2000). lee and lee (2008) argue that the environment emits many signals and cues about the characteristics of the site, and criminals use these cues to locate and identify easy targets. crime prevention through environmental design (cpted) could be used to manipulate the built environment to minimise opportunities for crime (crowe and fennelly, 2013). some design outcomes in nigeria increase instead of reducing the ease factor. fig. 1 shows poorly planted trees that aided a person to climb over a fence thereby compromising security. the choice of trees (species and characteristics) and their proper locations were not taken into consideration at the design stage. the crime problem in nigeria is multi-dimensional. the problem ranges from simple burglary to militancy and their criminal activities of murder, kidnapping, bombing and destruction of property, arson and armed robbery. the immediate response has been to surround sensitive and other fig. 1 poor planting can aid climbing over a fence using tree branch thereby compromising security public facilities with improvised barriers, intimidating guards, blocking of whole or parts of the roads around the facilities. fig. 2 shows the blocking off of part of the road in front of the nigerian national petroleum corporation (nnpc) towers, abuja, nigeria to public use to create the required standoff distance. this has caused considerable inconvenience to vehicular movement. it could have been avoided if this was considered at the design stage. this suggests that crime prevention (physical security) mechanisms are often considered as a retroactive add-on and implemented fig. 2 part of the road blocked to create required stand off distance at nnpc towers complex, abuja 21 journal of sustainable architecture and civil engineering 2017/1/18 after a crime has been committed rather than during the design development. these measures should have been considered at the design stage. generally, in nigeria crime prevention and security related issues are considered the concern of law enforcement and industrial security personnel and therefore are not holistically considered and integrated at the design and construction stages of project development of buildings. these responses and interventions show that there is a high priority placed on security and crime prevention by owners and users as a design consideration that architects should not sacrifice to achieve other design requirements. the responses also draw attention to the need to investigate why architects in nigeria do not holistically address issues of crime prevention in their designs. the aim of this paper, therefore, is to determine the factors that affect architectural design for crime prevention in nigeria. these factors analysed were drawn from the review of literature. designing should take a holistic approach in order to meet the challenges of crime and terrorism. treating crime prevention as an afterthought after the construction has been completed is not cost effective. however, the architect faces several challenges in the attempt to address crime prevention issues in his design. r. i. atlas (2013) identifies poor knowledge of crime prevention design principles and process, unavailability of building codes that enforce or encourage such designs, clients overlooking security issues in their brief to architects and poor collaboration with other professionals, especially security experts. furthermore, other challenges to the architect as noted by r. i. atlas (2013) include: _ determining crime prevention requirements: crime prevention needs should be determined at the beginning of a project’s programming and problem definition stage. _ knowledge of security technology: the rapid advances and innovation in the technology of security systems make keeping up-to-date a challenge. architects, as with other areas of specialisation, should be knowledgeable enough to be in a position to evaluate, specify and incorporate technical crime prevention mechanisms and equipment appropriately. _ understanding architectural implications of crime prevention requirements: architectural design is expected to incorporate the complicated and sometimes conflicting goals of crime prevention and other project variables and requirements. space should be designed to support the key crime prevention objectives of deter, detect, delay and deny access and rapid response to unauthorised access and criminal activities. the architect should translate these crime prevention concerns into design implications. m. press et al. (2001) consider collaboration and shared knowledge with client, manufacturers and crime prevention experts as a necessity since all could contribute to the design process. they argue that awareness and practical knowledge of crime resistant products among designers could encourage manufacturers to produce better products. they also point out the need to draw on the significant documented knowledge that exists on crime prevention for design. furthermore, they identify little understanding of the issues of crime prevention, a lack of specific knowledge that can be applied in design, reconciling the often contradictory demands of design and security, complexity of design issues as they relate to crime and access to research data that is either unavailable or difficult to obtain. j. warren (2010) asserts that the professionals’ ability to make informed decisions on the probability of crime occurrence (type, how and where) in a building will reduce the likelihood of the event occurring though design and use of appropriate crime prevention mechanisms. furthermore, the professional should be able to judge probability accurately when determining the best methods to reduce the likelihood of crime occurring in an area. v. horayangkura (2012) also notes that incorporating environment-behaviour knowledge into the design process also poses a challenge to architects. these factors individually or collectively are likely to affect architectural design for crime prevention in nigeria. factors affecting architectural design for crime prevention journal of sustainable architecture and civil engineering 2017/1/18 22 study area methodology and findings the study area is located in akwa ibom and cross river states in the south geo-political zone of nigeria. akwa ibom state was created from cross river state on 23 september, 1987. it lies between latitudes 4°33ˇ and 5°33ˇ north and longitudes 7°35ˇ and 8°25ˇ east. it is bounded on the north by abia state, on the east by cross river state, on the west by abia and rivers state and on the south by the atlantic ocean. the capital city is uyo. cross river state was created on 27 may, 1967 as south eastern state. the name was changed to cross river state in 1976. it is bounded on the north by benue state, on the east by the republic of cameroun, on the west by akwa ibom, abia ebonyi and enugu states and on the south by akwa ibom state and the atlantic ocean. it is located on the following co-ordinates: 4°57ˇ north and 8°19ˇ east. the capital city is calabar. the survey research method was adopted for the study. 132 questionnaires were administered to members of the nigerian institute of architects in akwa ibom and cross river states of nigeria. 93(70.45%) of the total number of questionnaire administered were completed and returned. six (4.54%) incomplete questionnaires were rejected. 87 completed questionnaires, representing 65.91%, were used for the study. the achieved sample is not biased by non-response as non-responders do not differ in any significant way from the respondents. this is a homogeneous sample. percentages and mean score analysis and ranking method were used as the analysis tools. interviews were also carried out with key architects with 12 to 37 years of practice experience. statistical package for social sciences (spss) version 20 was the software used for data analysis. the study sought to know if there is a role for architects in crime prevention and anti-terrorism practices in nigeria. likert scale was used to rate the respondents’ responses as follows, strongly agree – 5, agree – 4, disagree – 3, strongly disagree – 2 and not sure – 1. the results are presented in fig. 3. this result indicates that majority of the respondents totalling 85.1% strongly agree or agree that architects have a role in crime prevention. this study also sought to know whether crime prevention and other security issues are specific client’s request on the respondents’ projects. for this the rating was based on a “yes” or “no”. the result indicates that 56 respondents representing 64.4% indicated that crime prevention and other security issues are specific request of clients on their projects while 31 (35.6%) indicated that it is not. this result indicates that majority of the respondents have crime prevention and security as part of the client’s brief and instruction. fig. 3 descriptive results of the role of architects in crime prevention 48.30% 36.80% 5.70% 2.30% 6.90% strongly agree agree disagree strongly disgree not sure 48.30% 36.80% 5.70% 2.30% 6.90% strongly agree agree disagree strongly disgree not sure 48.30% 36.80% 5.70% 2.30% 6.90% strongly agree agree disagree strongly disgree not sure the major objective of the study was to determine the factors that prevent architects from addressing issues of crime prevention in their designs. ten factors were selected from the review of literature. to achieve this objective, the respondents were requested to rate the effect of these factors on their ability to address the issues of crime prevention in their designs of public buildings. a five-point 23 journal of sustainable architecture and civil engineering 2017/1/18 likert scale is used as follows; very high – 5, high – 4, moderate – 3, low – 2 and no effect – 1. the responses are analysed using the mean score analysis and ranking method. s. c. fan et al. (2010) adopted this method to determine the significant levels of critical factors for using group decision support systems in value management studies. similarly, a. o. odesola (2015) adopted this approach in assessing management-related factors affecting labour productivity in cross river state of nigeria. the ranking of variables was based on the mean scores of the responses. the scores and the subsequent ranking show what factors the respondents consider to affect architectural design for crime prevention more than others. an evaluation scale in line with the measuring scale was adopted to establish a baseline or cut-off point. a baseline mean of 2.60 was used to determine the significance of the factors. the results are presented in table 1. from table 1 the mean values of the factors have been sorted out in a descending order. the highest mean value (3.32) represented by rank 1 represents the most significant factor as rated by the respondents which is lack of documented examples in nigeria. this is followed by clients’ brief not specific on crime prevention (3.17), no crime prevention requirements in planning and building regulations in nigeria (3.05), inability to reconcile the demands of functions and aesthetics with security requirements (2.99, rank 4) and inability to estimate the probability of crime occurrence in proposed project (2.99, rank 5). where the mean is the same value the factor with the lowest standard deviation was ranked higher. table 1 ranks of factors that affect architectural design for crime prevention factors n mean standard deviation rank lack of documented examples in nigeria 87 3.32 1.196 1 client’s brief not specific on crime prevention 87 3.17 1.014 2 no crime prevention requirements in planning and building regulations in nigeria 87 3.05 1.120 3 inability to reconcile the demands of functions and aesthetics with security requirements 87 2.99 1.006 4 inability to estimate the probability of crime occurrence in proposed project 87 2.99 1.186 5 inadequate knowledge of crime prevention design principles and processes 87 2.91 1.030 6 inability to determine crime prevention requirements 87 2.91 1.085 7 poor knowledge of crime prevention products and mechanisms 87 2.82 1.029 8 no training on design for crime prevention 87 2.82 1.385 9 poor understanding of architectural implication of crime prevention requirements 87 2.74 1.146 10 n = total number of respondents; mid-point value = 2.97 discussion of findings the findings on the role of architects in crime prevention in fig. 3 shows that majority of the respondents (85.1%) strongly agree or agree that architects have a role in crime prevention. this implies that architects are becoming more and more involved in addressing social issues in their designs. this finding has three important implications namely, increase the relevance of architecture, expand its professional boundaries and bring about a proactive response to the issues of crime prevention. the implication becomes more obvious when viewed with the finding that majority of the clients (64.4%) specifically request that architects address issues of crime prevention and security in their projects. the clients’ specific request on crime prevention could be attributed journal of sustainable architecture and civil engineering 2017/1/18 24 to the fact that safety and security are serious social problems in nigeria with crime ranking high among the risks. this finding also implies that there is the tendency that architects’ knowledge of crime prevention design concepts and methodologies will increase since architects use clients’ brief for the project to collect information relevant to the project. the architect as a designer and a businessman has to ensure that the client is satisfied with the design and has value for his money. this finding of clients’ specific request on crime prevention draws attention to statement of royal institute of british architects that the client’s brief is the key driver or constraint for research activities for design. furthermore, what is contained in the client’s brief will determine to a very large extent what is contained in the design. the results in table 1 show that all the factors are significant with mean values above the 2.6 baseline. these factors are knowledge related. for example, lack of documented examples in nigeria relate to precedent and design knowledge, client’s brief not specific on crime prevention (design knowledge), no crime prevention requirements in planning and building regulations in nigeria (regulatory knowledge), inability to reconcile demands of function and aesthetics with security requirements (application knowledge) and inability to estimate the probability of crime occurrences in proposed project relates to environmental knowledge. this suggests that knowledge has a significant and positive effect on architectural design for crime prevention. knowledge helps architects to take good and informed design decisions. different types of knowledge are needed to improve the impact of architectural design. these findings draw attention to the observation of a. m. salama (2008) that there is a rise in demand for different types of knowledge in architecture. it also agrees with the statement of royal institute of british architects that the value of specialist sector knowledge is increasingly being recognised. a very important factor affecting architectural design for crime prevention is ‘lack of documented examples in nigeria’ ranked first. this finding echoes the need for nigerian architects to document and publish their works in order to make precedent knowledge available to students and practitioners. documented examples have three major functions namely, knowledge sharing, knowledge transfer and knowledge preservation. documented materials are the main sources of knowledge for design. this implies that lack of documented examples is a serious problem in the architectural design for crime prevention in nigeria. this draws attention to the findings of n. c. kayacetin and a. m. tanyer (2009) that 73.3% of the architectural organisations they studied strongly agreed or agreed that documented examples are the main sources of knowledge for design. this agrees with architect information provider number two (interviewed 18th december, 2015) with 30 years of practice experience that “materials, books and documents available to nigerian architects are mostly foreign which have to be adapted to local context. documented works in nigeria by nigerian architects are scarce or not available in areas like crime prevention design. architects in nigeria should, therefore, be involved in documenting their works to produce design and project examples that reflect perculiar circumstances of their projects.” conclusions and recommendations the results of the study have drawn attention to the increase in the understanding of the important role of the architect in the current fight against crime and terrorism. this role is a product of the recognition of the fact that the environment can be manipulated through design to reduce and/or prevent criminal and terrorist acts and also mitigate the effect of such attacks. using his experience and professional knowledge and in collaboration with other relevant professionals, the architect can contribute immensely to creating buildings and environments with built-in security measures. the significant factors affecting architectural design for crime 25 journal of sustainable architecture and civil engineering 2017/1/18 prevention draw attention to the need for architects in nigeria to acquire relevant knowledge on the processes and requirements for crime prevention design in order to effectively address crime prevention issues in their designs. the paper concludes that these factors have major effects on the ability of nigerian architects to design against crime because architectural design is knowledge dependent and knowledge driven. the paper recommends that architects in nigeria should be trained in physical security concepts and crime prevention through environmental design as part of formal architectural education training and/or professional continuing development programme. the skills acquired will enable them to easily transform security goals and objectives into design requirements. architects should also document their works and the processes involved in arriving at their final implemented designs, especially in the areas of security and crime prevention. these should include the problems, conflicts and trade-offs encountered in the process and how they were resolved. target selection process for residential burglary. crime prevention and community safety journal, 10, 19-35. https://doi.org/10.1057/palgrave. cpcs.8150055 marzbali, m., abdulla, a., razak, n., tilaki, m. (2011). a review of effectiveness of crime prevention by design approaches towards sustainable development. journal of sustainable development, 4(1), 160 – 172. national crime prevention institute (1986). understanding crime prevention. stoneham: butterworth publishers. odesola, a. o. (2015). assessment of management – related factors affecting construction labour productivity in cross river state of nigeria. covenant journal of research in the built environment, 3(2), 13 – 29. press, m., erol, r., cooper, r. (2001). design as a tool for social policy: the case for design against crime. paper presented at the fourth european academy of design conference, aviero, portugal. salama a. m. (2008) a theory for integrating knowledge in architectural design education. archnet-ijar, 2 (1), 100-128. stafford, m., chandola, t., marmot, m. (2007). association between fear of crime and mental health and physical functioning. am j public health, 97(11), 2076 2081. https://doi.org/10.2105/ ajph.2006.097154 warren, j. (2010). construction of meanings and personal identity in decision making of community safety professionals. phd thesis submitted to university of chester. referencesatlas, r. i. (2013). 21st century security and cpted: designing for critical infrastructure protection and crime prevention. boca raton: crc press. https:// doi.org/10.1201/b15046 bercovich, d. h. (2010). the fear society: design for safety. retrieved from www.essays.se/about/dana+hakim+bercovich crowe, t. d. (2000). crime prevention through environmental design: application of architectural design and space management principles. boston: butterworth-heinemann. crowe, t. d. and fennelly, l. j. (2013). crime prevention through environmental design (3rd ed.). new york: elsevier. fan, s. c., shen, q. p., luo, x. (2010). group decision support systems in value management. construction management economics, 28(8), 827 – 838. https://doi.org/10.1080/01446191003758171 fennelly, l. (1989). handbook of loss prevention and crime prevention, 2nd ed. boston: butterworth-heinemann. horayangkura, v. (2012). incorporating environment-behaviour knowledge into the design process: an elusive challenge for architects in the 21st century. procedia – social and behavioral sciences, 50, 30 – 41. https://doi.org/10.1016/j.sbspro.2012.08.013 kayacetin, n. c. and tanyer, a. m. (2009). exploring knowledge management in the practice of architecture: a pilot study in the turkish capital. metu jfa, 26(2), 279 – 308. https://doi.org/10.4305/metu. jfa.2009.2.14 lee, k. lee, j. (2008). cross-cultural analysis of perception of environmental characteristics in journal of sustainable architecture and civil engineering 2017/1/18 26 samuel o. ebong lecturer department of architecture, faculty of environmental studies main research area construction management; antiterrorism, crime prevention and security design address university of uyo, uyo, nigeria tel. +2348023144366 e-mail: samuelebong@uniuyo.edu.ng about the authors stella n. zubairu professor department of architecture, school of environmental technology main research area facility managemant address federal university of technology, minna, nigeria tel. +2348023750624 e-mail: stellazubairu@gmail.com remi e. olagunju associate professor department of architecture, school of environmental technology main research area sustainable housing and building maintenance & management address federal university of technology, minna, nigeria tel. +2347065003865 e-mail: olagunju@futminna.edu.ng 99 journal of sustainable architecture and civil engineering 2018/1/22 *corresponding author: jolanta.sadauskiene@ktu.lt review of bim implementation in higher education received 2018/07/02 accepted after revision 2018/09/10 journal of sustainable architecture and civil engineering vol. 1 / no. 22 / 2018 pp. 99-109 doi 10.5755/j01.sace.22.1.21116 © kaunas university of technology review of bim implementation in higher education jsace 1/22 http://dx.doi.org/10.5755/j01.sace.22.1.21116 jolanta šadauskienė*, darius pupeikis kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania introduction building information modelling (bim) creates integrated design process, where information flow from one computer application to another, throughout the project lifecycle, is possible, it relies on the development and use of common information throughout the disciplines of architecture, engineering, construction, and facilities management. for this reason, a lot of study programmes involved bim methodology into their curriculum. however all of them have different attitude or way of bim implementation. therefore the aim of this research work is to analyse the curricula of higher education institutions related with bim in lithuania, to identify and analyse disciplines related with bim and their relations in kaunas technology university and to identify gained bim competencies. the analysis of the disciplines related with bim shows that the strength of bim development in faculty of civil engineering and architecture study programmes is the interdisciplinary joint semester project. gained bim competencies in study programmes merge the fundamental knowledge of study field and digital technology management. those competencies are gained in undergraduate studies and it is a narrow volume of bim process. keywords: building information modelling, bim, education, civil engineering. “digital revolution” of construction field forces to change an attitude of activities in the architecture, engineering and construction (aec) industry. the digitalization in construction is established by using bim methodology in the building lifecycle. that means investors, developers, architects, designers, contractors, engineers of different fields, construction site managers, teachers of higher education institutions (heis) are involved into these activities. smooth collaboration process of design team (lead designer, architect, structural engineer, mechanical, electrical, and plumbing (mep) engineers etc.) is an important and actual issue of aec industry. however bim join not only stakeholders, but also create integrated design process (idp), where information flow from one computer application to the next throughout the project lifecycle is possible, it relies on the development and use of common information throughout the disciplines of architecture, engineering, construction, and facilities management (aec/fm) (vidalis et al. 2013). that means bim provides an opportunity to various users with different backgrounds to collaboratively work with a single bim model of a building (azhar et al. 2012, migilinskas et al. 2013 ). large aec industry companies are adopting bim as a tool in integrated project delivery (ipd) (wong et al. 2011). however exchanging information (models and other data) between different software platforms remains one of the industry’s biggest challenges on the way to fully integrate and make collaborations between project teams (pezeshki and ivari 2018). the biggest attention is on responsibility of the data and the information management. for this reason, the majority of study programmes in heis are fojournal of sustainable architecture and civil engineering 2018/1/22 100 cused on preparation of bim managers of the postgraduate level (abbas et al. 2016). the students of the undergraduate level are mostly working with bim technology especially with three-dimensional method in project design for the share information models (3d). however, they do not realize the connections through the whole bim process (fridrich and kubečka. 2014). the students of the undergraduate level usually find their jobs in aec industry just after finishing their studies due to the high demand of qualified engineers. they do not continue studies in postgraduate level and lose an opportunity to gain skills to manage information, apply and understand bim appropriately. the implementation of bim in the undergraduate level studies of higher education not only would influence the demand of bim professionals, but also would give new opportunities for students in their professional careers in the form of their ability to deal with new occupational challenges with high efficiency achieved by applying bim (brokbals and cadez 2017, wong et al. 2011). therefore, understanding of bim application opportunities and capabilities should be included into the curricula of the undergraduate level (xiao 2018, barison and santos 2010). according to the review of the literature, where a lot of study programmes were investigated (hietanen et al. 2008), bim implementation into the curricula methods are as follows: 1) information modelling skills goes parallel with common professional disciplines; 2) at first bim is introduced as a process, then bim modelling skills goes parallel with professional disciplines; 3) bim process is explained together with professional disciplines and bim modeling. this is confirmed by the investigation of a current position and associated challenges of bim education in the united kingdom higher education (underwood and ayoade 2015). overall findings here indicated that 24% of programmes are yet to incorporate bim; of this 6.9% are not considering incorporating bim. notably, 57% have incorporated bim into particular subjects. about 20% of programmes have developed standalone bim subjects, however only 13% have partially embedded bim, while only 7% have fully embedded bim in majority of their programmes. denzer and hedges (2008) state that before creating a comprehensive building design with bim, students must understand design fundamentals (including orthographic drawing) and know subjects like building technology/building science and professional practice. in the first two years, the focus is on the individual skills of modeling and analysing the model, while in the following years, it is more on teamwork and dealing with complexity and integration through collaboration. in the final year, students are expected to work on actual construction projects in collaboration with companies, as suggested by kymmell (2008). pezeshki and ivari (2018) outcome in his research that greater emphasis should be placed on supporting technical requirements to facilitate technology management and implementation across disciplines. the same author set that bim implementation into the curricula must be founded on adaptations to national situation and constraints. therefore the aim of this research is to analyse the curricula of bim education of different study programmes. bim education in lithuania lithuania, in comparison with other countries, has integrated bim quite late. in 2015 government of the republic of lithuania officially agreed to the initiative to digitalize lithuanian aec sector. at the same year, minister of environment approved guidelines for developing lithuanian aec sector strategic aims until 2020. particullar attention was focused on bim education. the initiators of bim promotion understand that a key success factor is – still missing – young professionals with adequate bim knowledge. due to the fact that there is a lack of skilled workers and engineers in lithuania, the initiative has joined with universities to sign an agreement to provide more education courses on digital construction. the biggest technological universities in lithuania – vilnius gediminas technical university (vgtu) and kaunas technology university (ktu) – adopted bim education in several review 101 journal of sustainable architecture and civil engineering 2018/1/22 study programs, which are related to aec industry. vgtu is focused on the postgraduate level, where separate course of bim management is delivered. the aim of this masters programme is not only to train specialists and to enhance knowledge of bim deployment and strategy but also to create and develop standards to guide and coordinate bim drafting. meanwhile ktu is focused in undergraduate level, where bim is involved in civil engineering disciplines. since the implementation of digital construction, ktu organizes seminars on digital construction for their students. the presentations are given by participants from private and public sectors. the aim of the seminars is to show students the importance of digital construction and bim in lithuania. moreover, bim is introduced and 3d design is delivered in a few colleges, for example, kaunas technical college. however, bim education is mostly limited to software training in isolated courses. according to statistical data, only 27 % of the stakeholder of aec industry use a bit of bim in lithuania. that means the literacy of bim use is very low. for this reason stakeholders of aec industry are focused on training their employees, which usually organized by heis of lithuania. this initiative will help specialists to enhance their competitiveness and their ability to participate in international construction projects. the main promoter of bim development in lithuania – public body “digital construction” – delivers dissemination of bim benefits, significance and stage of implementation. it organizes seminars and conferences every year. “digital construction” established the best ipd (bim project) awards for aec industry (digital construction 2014). bim adoption in curricula at ktu bim adoption in heis is a big challenge. there are a number of approaches due to adopting bim in the curricula (mcgough et al. 2013, barison and santos 2010, sacks et al. 2010, denzer and hedges 2008). the heis generally have the options of adapting their existing curricula to include bim for this purpose or teach bim as a separate course, or both (sacks et al., 2010). some heis adopt integrated project approach bim is involved into different disciplines (architecture, structures, mep systems etc.) to create communication based integrated project. this case usually is a task of undergraduate level. meanwhile other heis adopt bim project management approach, where bim is a separate course and more focused to develop bim management skills. this approach is usually delivered in postgraduate level. the adopting of bim as an integrated project approach and project management approach follows the requirements and demands of aec industry. the industry seeks to recruit the professionals who can apply knowledge to practical situations and both types of skills, integrated bim project and bim management, are necessary. this is more likely through courses, which introduce new developments in technology or new methods of project delivery to students (wong et al. 2011). faculty of civil engineering and architecture (fcea) at the ktu has chosen option of bim adoption in the curricula, where bim is a necessary part of civil engineering disciplines, which are delivered at the undergraduate level. since 2013 fcea study programmes were adopted to bim methodology and the main goals of the reform were: _ create a discipline of bim fundamentals by explaining the whole process; _ strengthen 3d drawing and design skills; _ start of interdisciplinary semester projects by involving as much disciplines as possible; _ use more bim software (modelling and simulation); _ strengthen a part of teamwork and communication; _ apply innovative study methods “pbl (problem based learning), design thinking etc. journal of sustainable architecture and civil engineering 2018/1/22 102 this research presents the current situation of bim education in lithuania. by using the implementation of bim courses in fcea at the ktu as a case study for integration of bim into higher education. package of faculty‘s study programmes is presented in table 1. objectives and methodology table 1 study programmes of the fcea level of degree title of the study programme specialization duration of the study programme, years undergraduate studies civil engineering _ building materials; _ construction technologies; _ structures of buildings 4 building services systems 4 postgraduate studies structural and building products engineering 1.5 construction management 1.5 sustainable and energy efficient buildings 1.5 integrated studies architecture 5 fig. 1 development of bim integrated project approach into the study programmes civil engineering and building services systems 3  strengthen 3d drawing and design skills;  start of interdisciplinary semester projects by involving as much disciplines as possible;  use more bim software (modelling and simulation);  strengthen a part of teamwork and communication;  apply innovative study methods “pbl (problem based learning), design thinking etc. 3. objectives and methodology this research presents the current situation of bim education in lithuania. by using the implementation of bim courses in fcea at the ktu as a case study for integration of bim into higher education. package of faculty‘s study programmes is presented in table 1. table 1. study programmes of the fcea level of degree title of the study programme specialization duration of the study programme, years undergraduate studies civil engineering  building materials;  construction technologies;  structures of buildings 4 building services systems 4 postgraduate studies structural and building products engineering 1.5 construction management 1.5 sustainable and energy efficient buildings 1.5 integrated studies architecture 5 track of bim development into the undergraduate study programmes of civil engineering and building services systems is shown in fig. 1. the used software in the mentioned study programmes is described in table 2. 103 journal of sustainable architecture and civil engineering 2018/1/22 table 2 the used software in the study programmes of fcea the software description revit is one of the most popular, wide use bim software package intended to develop (model) various disciplines as architecture, structures and building services systems (mep). it allows users to design a building or structure in 3d, annotate and animate the model, collaborate between the disciplines by using cloud-based technologies, access information from the building model’s database etc. tekla structures is very useful tool for detailing of steel, concrete, timber and even glass structures. it has good possibilities to prepare detailed drawings for production of structures and to draw detailed elements as welding’s, reinforcement bars, bolts, screws, rivets etc. autocad is a well-known, classical cad (computer-aided design) software solution intended for drawing and drafting. autocad is used across a wide range of industries, by architects, project managers, engineers, graphic designers, town planners and many other professionals. dds-cad software solution intended for modelling the building services systems (mep systems) as heating, ventilation and air conditioning (hvac), plumbing systems as water supply and sewerage systems either electrical installations. civil 3d is a specified solution built on autocad platform intended for design of roads and their infrastructure (drainage, storm sewer system, water supply, traffic management etc.). magicad is a supplementary software package for revit or autocad platforms intended for mechanical, electrical and plumbing design. it enables modelling and engineering calculations as well. sofistik software solution for structural calculations, analysis and optimization of building’s structure based on finite elements method. navisworks is a 3d design review package primarily used to combine models from different disciplines (architecture, structures, mep models etc.). it allows users to navigate around them in realtime and review the model using a set of tools including comments, interference detection, measurements, 4d (time) simulation, photorealistic rendering etc. first semester of the studies is intended for development fundamental skills of two-dimensional method in project design (2d) (including orthographic drawing) in autocad environment by designing an architectural discipline of detached residential building. second semester is intended to develop already started design in 3d with a revit software in the study subject basics of spatial design. fourth semester is intended to design the industrial building and to develop not only 3d of architectural and structural disciplines, but also addition and use of attribute data (materials, properties, producer, class etc.). the essentials of the mentioned track is a continuation of the design, development from 2d to 3d and addition of more and more disciplines and attribute data. the specialized and more detailed trainings of bim software are included in the 3rd year curricula of civil engineering and building services engineering study programmes. at that moment students already have main professional skills of structures, materials, construction technologies and building services systems (heating, ventilation, and air conditioning (hvac), water supply etc.). each discipline is covered by particular study subject of information modelling, which is intended to create specific bim data and take advantage from that. moreover, before the starting specialized training of bim software, students are introduced with a bim fundamentals. this cycle of the studies is involved into all specializations and are intended for understanding bim as a process. also such aspects as the main bim standards (employer’s information requirement (eir), bim execution plan (bep), bim protocol), importance of classification system, data exchange issues, cloud based collaboration and communication, level of development (bim level of development (lod)) are explained. learning outcomes of mentioned study subjects are presented in table 3. particular attention is dedicated to development of teamwork, smooth collaboration and communication skills. journal of sustainable architecture and civil engineering 2018/1/22 104 table 3. learning outcomes of specialized bim disciplines s pe c. s u bj ec t s o ft w ar e description learning outcomes b ui ld in g m at er ia ls in fo rm at io n m od el lin g of m an uf ac tu rin g of c on st ru ct io n p ro du ct s r ev it the aim and the focus of the subject is on information modelling of construction products manufacturing technologies, parametrization and classification of construction products. also it’s coding systems, level of details importance, use of bim data libraries and templates. _ ability to search, gather, and interpret individually various data of the information modelling of manufacturing of construction products, perform logically data analysis using different quantitative computer methods designed for the solution of engineering problems. _ ability to apply the knowledge and understanding to identify, formulate, and solve the problems of bim using existing methods of analysis and parametric modelling of construction products. _ ability to apply appropriate parametric models in the field of manufacturing of construction products, based on logistic, safety, sustainable development, environmental and economic aspects. c on st ru ct io n te ch no lo gi es in fo rm at io n m od el lin g of c on st ru ct io n p ro ce ss es n av is w or k r ev it the aim is to clarify the objectives of the specific implementation construction technologies methods and processes, using necessary information tools. the knowledge about the organization of construction works needed to implement bim is learned and needs of specialized jobs and how company staff perceives their responsibilities and roles. also, this subject focuses on an evaluation of structural 3d buildings models and applying appropriate construction methods, a design of technology and organization, chain calculation of material and technical supply, planning of the measures for quality control and safety, creating of building site layout, scheduling and budgeting of building works (4d/5d) and assessment of status control within bim. _ ability to search, gather, and interpret individually various data of the information modelling of construction technology, construction, project organization and quality assurance principles, perform logically data analysis using different quantitative computer methods designed for the solution of engineering problems. _ ability to apply the knowledge and understanding to identify, formulate, and solve the problems of bim using existing methods of analysis and parametric modelling of the technical facilities and their management techniques and construction methods. _ ability to apply appropriate parametric models in the field of construction technology, based on design options, possible methods of construction, according to the construction environment, restrictive conditions, landscape, heritage, aesthetic, sustainable development and architectural issues, economic factors and expected operating conditions. b ui lid ng s tr uc tu re s in fo rm at io n m od el lin g of b ui ld in g s tr uc tu re s te kl a the aim is to analyse the loads and actions for object structures using necessary information tools, to perform the calculation of forces into the structural elements and joints of buildings and constructions, to perform the analysis of calculation results using the methods of computer design, to draw the object plan, sections and more complicated joints of connected structures, to prepare 3d model according to requirements of a technical project. _ ability to search, gather, and interpret individually various data of the information modelling of structural elements of buildings, perform logically data analysis using different quantitative computer methods designed for the solution of engineering problems. _ ability to apply the knowledge and understanding to identify, formulate, and solve the problems of bim using existing methods of analysis and parametric modelling of structural elements. _ ability to apply appropriate parametric models in the field of structural engineering, based on logistic, safety, sustainable development, environmental and economic aspects. b ui ld in g s er vi ce s s ys te m s b ui ld in g in fo rm at io n m od el lin g of s er vi ce s s ys te m s r ev it d d s -c a d the aim is to acquire theoretical and practical knowledge about building engineering systems information modeling through innovative software, to acquire knowledge about the work of the procedure, succession, responsibility and possible consequences, to gain skills to coordinate their actions and solve a common engineering problems, justify the chosen solution options and methods, able to prepare technical documentation and present prepared building information model with complex engineering systems. _ ability to generate and express ideas in a reasoned manner and accept constructive criticism regarding engineering systems. _ ability to use information technology and advanced bim software to solve engineering systems problems and produce a 3d model. _ ability to process engineering systems information model, to carry out a systematic collision analysis, prepare a technical documentation of materials and equipment, to evaluate critically the application of technologies of the study area in legal, economic and functional terms and in respect of the impact on an individual and environment. 105 journal of sustainable architecture and civil engineering 2018/1/22 the paper examines the status of bim in the two aspects: _ identify and analyse disciplines related with bim and their relations in ktu; _ analyse managing aspects and challenges of an interdisciplinary joint semester project. identify and analyse disciplines related with bim in order to determine the impact of bim integration on the content of the study programmes, the discipline packages taught in the fcea engineering profile (table 1.) were analysed. the results of the study are presented in fig. 2. results fig. 2 the changes in curriculums of study programmes in fcea analysis of the contents of the mentioned study programmes shows that bim is incorporated in particular subjects of the civil engineering study programmes 27% of all disciplines package, in curricula of the building services engineering study programmes 31%, in the structural and building products engineering – 8 %, in the construction management – 10 %, in the sustainable and energy efficient buildings – 9 %. analysing developed standalone bim subjects: the civil engineering study programme has 10% and the building services engineering – 5 %, the structural and building products engineering – 5 %, the construction management – 8 %, the sustainable and energy efficient buildings – 11 %. analyse an organization of interdisciplinary semester project the interdisciplinary semester project starts in the 3rd year spring semester in the architecture study programme to develop architectural and site plan disciplines. in the 4th year autumn semester in civil engineering and building services engineering study programmes includes development of structural, fabrication technology, building services systems, construction planning and cost estimation disciplines. several disciplines joins the project from faculty of electrical and electronics engineering, electrical power engineering and automation and control study programmes (fig. 3). in most cases projects tasks are linked with real situations and are offered by participants of aec industry journal of sustainable architecture and civil engineering 2018/1/22 106 (general contractors, fabricators, designers etc.). participants usually are involved into the project and acts as a client or consultant. in some cases tasks of the projects are linked and relevant for the public sector (municipalities, governmental institutions, public bodies etc.). fig. 3 schedule schema of interdisciplinary semester project disciplines 3rd course spring semester (architecture study programme) 4th course autumn semester (civil engineering, building services engineering, electrical power engineering and automation and control study programmes) final architecture site plan building structures construction technologies fabrication technology of building materials building services systems (hvac, water supply and sewerage) electrical power automation and control conceptual design design solution, detailed design, analysis simulation quantity take-off, scheduling, cost estimation presentation of the interdisciplinary semester project concerns and challenges of the project are well known for teachers and professionals of stakeholders who apply bim (cinelis and janilionis. 2013). the first challenge is the integration of different disciplines due to the use of different software. usually we use revit, tekla structures, ideastatica, dlubal, dds-cad, nawisworks. in this case, data exchange is possible only with a help of industry foundation classes (ifc) standard, but the lack of data consistency is still a big issue nowadays. actually, students are free to pick up the software type and vendor, but we prefer and encourage “openbim” concept. second challenge is to ensure smooth collaboration, communication and teamwork. in this case, students are encouraged to use cloud based technologies, specific software for better communication collaboration and management (projectwise, bim360 etc.). discussion introducing bim virtual worlds into education stand out as a promising technological approach to constructive learning and productive teaching (underwood and ayoade 2015). but, how it was mentioned previously, the national market regulates the demand for skills and competences of ace engineers. lithuania took the decision due to bim development and implementation too late compering with other eu countries. that is the reason in order that organizations in civil engineering field use 2d method in project design. according to statistical data, 73 % of civil engineering organizations use autocad software and design on 2d environment. therefore the students gain 2d skills in the first semester that need for small and medium organizations, which are not using bim methodology in their projects. this method of project design is dying, therefore particular attention in curricula of ktu is focusing on bim education. the created curriculum, where bim track 107 journal of sustainable architecture and civil engineering 2018/1/22 is included, gives opportunity for students to not only get acquainted with bim methodology but also gain the fundamental knowledge of building materials, structural and engineering systems design, construction technology, manufacturing of building products, management, economy and etc. this knowledge as specific information is included in the bim project. but for this process students have to know the basics of it and have to manage specifics software. that means the fundamental knowledge of civil engineering should go in parallel with it. students are trained to use the digital tools and to implement it in different kind of design processes. also, the strength of bim development in fcea study programmes is the interdisciplinary joint semester project, where in the created model, there are inserted data from different disciplines of civil engineering, architecture, electrical, automation and control. the weakness of presented bim education at ktu is a narrow volume of bim process. the simulation and analysis related only to fundamentals issues. the stage of project design, where is done environmental performance analysis (6d) and stage of project design, where is information relating to the whole life cost, including operation and maintenance of the completed building (7d) should be included in postgraduate level. faculty of civil engineering and architecture at ktu has this possibility, because it has 3 study programmes (table 1.). the deeper analysis should be made on structural and building manufacturing possibilities related a life cycle of the building by the students of structural and building products engineering study programme. the students of construction management study programme might develop issues related project management and integrate in semester project as a bim coordinators. they also might provide requirements for operation of building (6d stage of bim). the students of building engineering systems study programme might do simulation related energy efficiency of a building that means they will develop the project in 7d stage. the results of the investigation show, that fcea is working on the issue of bim adaptation and development in delivered study programmes (fig. 2). however, the subjects, which are related to bim, in the curricular of the fcea study programmes are 2-3 times less comparing to a statistical data of heis the united kingdom (fig. 4), which are presented by underwood and ayoade (2015). that means, bim education in ktu is not quite enough and should be developed and improved. fig. 4 comparing the bim adoption in curriculum between fcea of lithuania (lt) and united kingdom 9 the results of the investigation show, that fcea is working on the issue of bim adaptation and development in delivered study programmes (fig. 2). however, the subjects, which are related to bim, in the curricular of the fcea study programmes are 2-3 times less comparing to a statistical data of heis the united kingdom (fig. 4), which are presented by underwood and ayoade (2015). that means, bim education in ktu is not quite enough and should be developed and improved. fig. 4 comparing the bim adoption in curriculum between fcea of lithuania (lt) and united kingdom in lithuania, bim starts to enforce at the legislative level. from the 1st of july 2022 will become compulsory to use bim methods for the design and construction of all newly constructed complex and high-value public sector buildings, which undoubtedly will lead to greater transparency and it will encourage to search for civil engineers with the competences of digitalization. for this reason, bim implementation and development in heis of lithuania is an important thing. the opportunities of bim education leads to collaboration among the different public sectors, which relates research and development (r&d) projects, bim dissemination, the teaching of staff, the legalization of aec and etc. conclusions the analyses of disciplines related with bim and their relations in ktu show that the strength of bim development in fcea study programmes is the interdisciplinary joint semester projects, where not only fcea study programmes like architecture, civil engineering, building services systems are involved but also study programmes from faculty of electrical and electronics like automation and control and electrical engineering. the results of the investigation show, that bim education in ktu is not quite enough and it should be developed and improved. gained bim competencies in fcea study programmes marge the fundamental knowledge of study field and digital technology managed. those competencies are gained in undergraduate studies and it is a narrow volume of bim process. the 6d/7d stage of bim as estimation, sustainability, facility management and operation should be included in postgraduate level. in lithuania, bim starts to enforce at the legislative level. from the 1st of july 2022 – it will become compulsory to use bim methods for the design and construction of all newly constructed complex and high-value public sector buildings, which undoubtedly will lead to greater transparency and it will encourage to search for civil engineers with the competences of digitalization. for this reason, bim implementation and development in hei of lithuania is an important thing. journal of sustainable architecture and civil engineering 2018/1/22 108 in lithuania, bim starts to enforce at the legislative level. from the 1st of july 2022 will become compulsory to use bim methods for the design and construction of all newly constructed complex and high-value public sector buildings, which undoubtedly will lead to greater transparency and it will encourage to search for civil engineers with the competences of digitalization. for this reason, bim implementation and development in heis of lithuania is an important thing. the opportunities of bim education leads to collaboration among the different public sectors, which relates research and development (r&d) projects, bim dissemination, the teaching of staff, the legalization of aec and etc. the analyses of disciplines related with bim and their relations in ktu show that the strength of bim development in fcea study programmes is the interdisciplinary joint semester projects, where not only fcea study programmes like architecture, civil engineering, building services systems are involved but also study programmes from faculty of electrical and electronics like automation and control and electrical engineering. the results of the investigation show, that bim education in ktu is not quite enough and it should be developed and improved. gained bim competencies in fcea study programmes marge the fundamental knowledge of study field and digital technology managed. those competencies are gained in undergraduate studies and it is a narrow volume of bim process. the 6d/7d stage of bim as estimation, sustainability, facility management and operation should be included in postgraduate level. in lithuania, bim starts to enforce at the legislative level. from the 1st of july 2022 – it will become compulsory to use bim methods for the design and construction of all newly constructed complex and high-value public sector buildings, which undoubtedly will lead to greater transparency and it will encourage to search for civil engineers with the competences of digitalization. for this reason, bim implementation and development in hei of lithuania is an important thing. conclusions acknowledgment this research was undertaken with the benefit of a grant from the nordplus programme of the nordic council of ministers, nordic_bim_edu – development of skills for building information modelling (bim) in nordic countries higher education (project no. nphe-2017/10042 ). abbas, a., din, z.u., farooqui, r. integration of bim in construction management education: an overview of pakistani engineering universities. procedia engineering, 2016; 145: 151 – 157. https://doi. org/10.1016/j.proeng.2016.04.034 azhar, s., khalfan, m., maqsood, t. building information modeling (bim): now and beyond, australasian journal of construction economics and building, 2012;12(4): 15-28. https://doi.org/10.5130/ ajceb.v12i4.3032 barison, m. b., santos, e. t. review and analysis of current strategies for planning a bim curriculum, proc., cib w78 2010 27th international conference, 2010; 1-10. barison, m. b., santo,s e. t. bim teaching strategies: an overview of the current approaches, proceedings of the international conference on computing civil and building engineering. brokbals, s., cadez, i. academic teaching of bim – development – status quo – demand for action. bautechnik, 2017; 94(12): 851-856. https://doi. org/10.1002/bate.201700100 cinelis, g., janilionis, v. building information modeling in architectural digital design education: questions and answers, journal of sustainable architecture and civil engineering, 2013; 1(2): 3-10. https:// doi.org/10.5755/j01.sace.1.2.3281 denzer, a. s., hedges, k. e. from cad to bim: educational strategies for the coming paradigm shift, conference: architectural engineering conference (aei) 2008, doi: 10.1061/41002(328)6. https://doi. org/10.1061/41002(328)6 fridrich, j., kubečka, k. bim – the process of modern civil engineering in higher education. procedia social and behavioral sciences, 2014; 141: 763 – 767 https://doi.org/10.1016/j.sbspro.2014.05.134 references 109 journal of sustainable architecture and civil engineering 2018/1/22 hietanen, j. and drogemuller, r. approaches to a university level bim education, iabse conference, 2008, helsinki, finland. kymmell, w. building information modeling: planning and managing construction projects with 4d cad and simulations, new york: mcgraw hill, 2008; 270 p. isbn: 9780071494533. mcgough, m., ahmed, a., austin s. integration of bim in higher education: case study of the adoption of bim into coventry university’s department of civil engineering, architecture and building. sustainable building conference 2013, 394-403. migilinskas, d., popovb, v., juocevicius, v, ustinovichius, l. the benefits, obstacles and problems of practical bim implementation. 11th international conference on modern building materials, structures and techniques, mbmst 2013, procedia engineering 2013; 57: 767 – 774. https://doi. org/10.1016/j.proeng.2013.04.097 pezeshki, z., ivari, s.a.s. applications of bim: a brief review and future outline. arch computat methods eng, 2018, 25: 273-312. https://doi.org/10.1007/ s11831-016-9204-1 sacks, r., radosavljevic, m., barak, r. requirements for building information modeling based lean production management systems for construction, automation in construction, 2010; 19(5):641-655. https://doi.org/10.1016/j.autcon.2010.02.010 skaitmeninė statyba. on development of bim methodology and digital construction in lithuania over the period 2014-2020, 2014: 1-12. vidalis, s. m., harrisburg, p. s., cecere, j. partnering with industry and higher education on bim. proceedings of the 2013 conference for industry and education collaboration, proceedings: american society for engineering education, 2013: session etd 455. wong, k.a., wong, k.f., nadeem, a. building information modelling for tertiary construction education in hong kong. journal of information technology in construction, 2011; 16: 467-476. underwood, j., ayoade, o. current position and associated challenges of bim education in uk higher education, baf bim academic forum, 2015, march, 44 p. xiao, j. building information modelling competency among civil engineering and management students team-based learning. journal of professional issues in engineering education and practice, 2018; 144(2): 765-778. jolanta šadauskienė assoc. professor kaunas university of technology, faculty of civil engineering and architecture main research area energy efficiency of buildings, heat transfer and thermal insulation, building envelope humidity behavior, bim address studentu st. 48, lt-44403, kaunas, lithuania tel. +370 37 350453 e-mail: jolanta.sadauskiene@ktu.lt darius pupeikis assoc. professor kaunas university of technology, faculty of civil engineering and architecture main research area bim, heat transfer and thermal insulation, thermal physic address studentu st. 48, lt-44403, kaunas, lithuania tel. +370 37 350453 e-mail: darius.pupeikis@ktu.lt about the authors journal of sustainable architecture and civil engineering 2015/4/13 12 journal of sustainable architecture and civil engineering vol. 4 / no. 13 / 2015 pp. 12-17 doi 10.5755/j01.sace.13.4.13200 © kaunas university of technology received 2015/07/11 accepted after revision 2015/07/29 aspects for evaluation of the effect of natural and artificial bodies of water to protected areas’ landscape jsace 4/13 aspects for evaluation of the effect of natural and artificial bodies of water to protected areas’ landscape corresponding author: nijole.lin@gmail.com http://dx.doi.org/10.5755/j01.sace.13.4.13200 nijolė piekienė, antanas stančius klaipeda university, architecture, design and art department k. donelaičio ave. 5, lt-92144 klaipeda, lithuania vilnius gediminas technical university, faculty of architecture, department of architectural fundamentals and theory pylimo str. 26/1, lt-01132 vilnius, lithuania the landscape how a person usually understands it is the visible surface of the earth environmental image. this is a reflection of natural processes and a reflection of cultural change, which constantly changes across time and space. it is the foundation of national identity and is a part of life quality. understanding, protecting, managing and forming landscape’s identity and concept as an evolving phenomenon at the same time meeting the economic, social, cultural, ecological and aesthetic needs of the public is one of the top priority goals of the state (bučas, 2001). landscape as a term is associated with art, history, geography, ecology, politics disciplines and planning and design. the landscape can only be created by natural processes the natural landscape or landscape, which felt human intervention, is called cultural landscape. cultural landscape has a plethora of man-made objects buildings, roads, bridges, quarries and other engineering infrastructure. the novelty of the work: this work extends the knowledge on the lithuanian state parks’ landscape. the paper first describes bodies of water as a natural and urban element that affects protected areas’ landscape. keywords: aesthetics, landscape, protected areas, water. the natural landscape’s main formants are terrain, surface and ground waters, flora and fauna. natural and cultural landscape is constantly changing under the influence of both natural and social processes (grecevičius, godienė, 2013). the result of these changes will depend on the number of symbols and meanings, public cultural diversity and identity that will be integrated into the landscape. naturally and historically formed landscape, landscape’s architecture and its aesthetic value, expression of the terrain and hydro graphic network elements are intensely altered, elements of the urban environment are built, serving the needs of modern man, regardless of environmental conditions. existing elements of natural or urban landscapes are formed in an expression which enriches the landscape, shaped by the work and suitable recreational spaces, forms a visually attractive environment. scientists investigating the environmental attractiveness aesthetics, emphasizes introduction 13 journal of sustainable architecture and civil engineering 2015/4/13 the aesthetics of the environment affects our daily activities, and the accelerating urbanization of natural landscape is rapidly changing human lives and the environment, reduces the landscape’s aesthetic potential. the main objective of the national strategy for sustainable development regarding the countryside’s and biodiversity’s conservation and development is preservation and enhancement of the most damaged elements of the landscape, restoration of aesthetic values of the landscape and the traditional rural landscape, its visual pollution (national, 2003). the article deals with water’s as a natural element’s of the landscape impact to protected areas’ landscape. in the landscape of protected areas, assessing the development by the principles of sustainable development, is regarded so that the water does not become a more significant aesthetic dimension of other landscape elements. the assessment of water facilities should take into account the social, historical and aesthetical, as well as functional considerations. of course, if it tune in to the surrounding environment, the water facility itself creates aesthetic value, but just aesthetical aspects is not the main point of evaluation. the simplest water facility can serve as just the refreshment point, drinking water source. commercially thinking, those devices can have pleasure and entertaining force, also water facilities can also serve as an “urban oasis”. water installation can be used as a constant or a temporary representative measure. objective. describe the water as one of the components of the landscape, impact to protected areas’ landscape, in aesthetic aspect. the paper scientific literature is used, as well as the normative documents and other sources’ analysis with data on protected areas in lithuania regarding the landscape protection and development capabilities, their assessment summary; water’s aesthetic potential is evaluated in protected areas in the landscape. the study was conducted in accordance with systematic and comparative analysis methods. methods results water in historical perspective the landscape is shaped by natural and anthropogenic factors which satisfy the biological, social, economic, residential, working and leisure environments’ requirements. to achieve these objectives, it is necessary to know the landscape and to take into account it’s planning, the evolution of the landscape and its features, values, ecological, aesthetic, social and economic functions and local communities and the whole society’s expectations. lithuania landscape cannot be built without the aesthetics of water, forests, greenery and constructions. prior to the 20th century, the landscape was dominated by the traditional natural landscape elements, such as fields, meadows, ponds, trees, landscapes were urbanized later by adding man-made elements farmsteads, roads, structures, dams. a desirable result, when the newly formed landscape components are compatible not only with each other but also fit in with the pre-existing forms. the communications between the components in the landscape is determined by the specific features of the landscape. written historical sources about bodies of water in urban areas are dated back from ancient times. greeks left a great contribution to the development of landscape objects of architecture. they richly planted urban gardens with trees and decorated with fountains and sculptures (mateckis, 2008). gardens for gymnasts and philosophers were being developed, which had bodies of water. a water supply and sewerage had also been developed. certainly, romans had advanced even further in who focused on urban water supply and sewage disposal. roman cities were much more decorated than the greek cities, so they had more numerous and diverse fountains and outdoor pools, and the consul agrippa built 700 pools and 500 fountains in rome. nevertheless, it should be noted that during the roman republic establishment period, as compared to the greek cities, there were not many landscape architectural objects and journal of sustainable architecture and civil engineering 2015/4/13 14 their abundance emerged only in the imperial period. at that time the sacred groves had been cherished, near which water sources had been constructed. urban public gardens had been constructed, in which fountains and running water pools for bathing were built. the townspeople who installed small gardens in their homes, did not forget to leave some space for a small pool or a fountain (mateckis, 2008). h.v. morton (morton, 1966), while researching roman fountains, also discusses all the ancient water facilities’ development and mentions that the water technologies greeks most likely took over from persia. yet they not only took it over, but perfected. samalavičius explores the important values of sacred water, emphasizing that the symbolism reveals its extraordinary value (samalavičius, 2000). however, he notes that in aesthetic aspect antique greek cities far surpassed roman cities, but from an engineering point of view, the latter ones have gone further. the significance of water’s destructive power is well known. maggie toy (maggie, 1995) while discussing this issue, identifies the relation between water and architecture as inevitably resulting in structural problems that a great deal of effort had been devoted to keeping the water out of the building (to protect from the rain, mold, etc.) and no less, or even more so they need to let the water in at the same time, inevitably constructing weak points. from historical times until now there are two approaches to water and its aesthetics. in one case, water is seen only as a functional element, it is avoided, and urban plans designed so that the river and bodies of water are in the outskirts of urban settlements. another trend is the reverse: the objective is to add the bodies of water into the human living environment and integrate into the public space, not only as a functional element, but also as an important ecological, aesthetic, and psychological factor. modern times of technology-using public are given a chance of potential activities in natural environment, natural bodies of water, and according to samalavičius, have become a target of advanced engineering developers (samalavičius, 2000). how they will adapt to modern needs and how it will integrate into the natural environment is an important task for developers. in order to preserve the natural and cultural heritage of territorial complexes and objects, landscape and biodiversity, then ecological balance in the landscape, natural resources, sustainable use and restoration must be ensured (protected ..., 2002), protected areas, national parks are to be established also. the most valuable aspect of state parks is its unchanged or minimally changed landscape. lithuanian constitution states that the republic of lithuania’s rights include: underground, as well as nationally significant internal waters, forests, parks, roads, historical, archaeological and cultural objects. in addition, the constitution prohibits citizens the destruction of land and the underground and pollution of water and air (the constitution of the republic of lithuania, 1992). water’s forms of expression in the landscapes of sea and lagoon in state parks fig. 1 the water is inseparable from the aesthetic and cultural upbringing of people. seaside regional park critical areas are national parks. they are characterized by historical, architectural, cultural, scientific, aesthetic, ecological and dendrological values (greenery, 2007). coastal and seaside silhouette shapes the national parks in these areas: the curonian spit national park and seaside regional park and the nemunas delta regional park. the bodies of water in these parks are used for aesthetic and recreational purposes (e.g. fig. 1, fig. 2.). 15 journal of sustainable architecture and civil engineering 2015/4/13 the curonian spit national park (e.g. fig. 3) as a unesco world heritage site, has a historical, architectural, cultural, aesthetic value. the picturesque strip of land between the lagoon and the baltic sea is a universally valued landscape. and with an increasing number of contemporary works of architecture, reflecting the characteristically formed architecture, their shape, volume, color and decorative elements –fascinating and attractive new coastal and seaside coastal compositional element. in this context, it is necessary to mention minge village (e.g. fig. 4) with natural surroundings as atypical example of human activity. this village located in the lowlands is sometimes called the lithuanian venice. indeed, in lithuanian culture it is not common to have a major part of economic and social activities of the people to revolve around a river. although the region (western lithuania, nemunas lowlands) due to long flooding has homes with higher foundations and boats a widespread phenomenon (butkus, 2009). for originality, uniqueness, coastal and seaside urban landscape has been formed, based on local circumstances. state parks‘ silhouette is shaped by traditional construction imitating the redtiled gable or reed roofs, coastal lifestyle characterizing a marina, fishing or recreational boats, nets (e.g. fig. 5-6). fig. 2 water as a natural resource for recreation. nemunas delta regional park fig. 3 the curonian spit national park – a peninsula between the lagoon and the baltic sea fig. 4 the river in minge village – a means of transport and entertainment venue fig. 5-6 seaside regional park, representing the harmony of old and new architecture nemunas delta regional park from the curonian spit national park is combined, but is also divided by the lagoon. the curonian spit, because of the ever changing landscape of sandy landscape, the people living here lived under special conditions. the curonian spit landscape reflects the centuries of people living in extreme conditions created by the history, nature, architecture and urbanism and intangible heritage (piekienė, 2013). it is the tangible and intangible heritage that journal of sustainable architecture and civil engineering 2015/4/13 16 provides the curonian spit landscape its distinctiveness, which in the year 2000 was evaluated by the unesco general conference and the world heritage list and now is an outstanding universally valued as a cultural landscape (bučas, 2007). the water in the curonian spit formed the nature, culture and architecture. it is safe to say that water influenced the seaside and coastal towns, villages and settlements in their appearance. in the twenty-first century a popular leisure time is in nature, an ecologically clean environment. this results in a growing number of people, increasing use of land resources and increasing human alienation from nature. not often a person can go out of the city, so the nature “comes” to the cities, by the installation of public spaces with natural elements. the most common public spaces that provide refreshment and psychological comfort are formed by water (stančius, 2015). the purpose of urban public spaces in the urban landscape is its multifunctional application. multifunctionality or mixed use is understood as a complementary mix of features in a given area (bučys, 2009). water as one of the most important natural elements in the urban environment in towns of lithuania are poorly evaluated: the quay concreted, built next to a busy highway, the inner blocks of space are isolated from water, active pedestrian zones concentrated in the more remote areas from the water (čereškevičius, 2013). in addition, many cities and towns face territorial development planning and designing problems: land configuration, the lack of public spaces, modern architecture invasion in historic environments and so on. the ratio of public spaces that are dominated by water and protected areas, particularly in the context of urban conservation areas, are regarded ambiguously. the visual spaces of landscape in state parks are not attractive as a single, unique state park which facilities include significant cultural monuments that are protected by the state or other objects of cultural heritage, but also the intangible elements of the environment, as a local identity, its cultural character, influence the quality of the landscape. some state parks’ value can be related not only to the amount of space, quality of recreational resources, but also with those elements of connection with the siege in adjacent objects, territories (piekienė, 2015). bodies of water form a public space in seaside regional park of the nemunas delta regional park and the curonian spit national park. water creates the marinistic image of these parks, the public spaces in contact with water fully exploit and expand their recreational potential. it is important to note that the giruliai slopes to the sea in seaside regional park and neringa dune relief of the curonian spit national park are strictly protected in lithuania (stauskas, 2007) and all economic activities are defined by law. since water is a constantly changing, but also static element of the landscape, it aids in forming architectural and aesthetic landscape view. in addition, the water in the landscape is not only a decorative element, but it creates a microclimate, forms recreational space. according to an architect v. stauskas, bodies of water affect architectural decisions and the results in three aspects: physical, physiological, and aesthetic (stauskas, 2000). water as a public space 1 water influence to lithuania’s landscape of protected areas has not yet been analyzed in detail, because there is not enough data on the interaction of water with other natural and urban elements. to assess the sustainable development approach of natural and urban landscape elements first all elements’ complexity is analyzed so that the water does not become a more significant aesthetic dimension than other landscape elements. 2 the analysis of water‘s impact on the landscape in lithuanian and foreign literature re-vealed that water, as the formant of landscape‘s aesthetic, is known since classical antiquity. written sources mention the huge contribution of the ancient greek landscape architecture object creation using the water. conclusions 17 journal of sustainable architecture and civil engineering 2015/4/13 3 the national parks of landscape evaluation found that the picturesque meadow from the lagoon and the baltic sea with the authentic architectural objects all are a valuable characteristic of the complex, making their conservation techniques and principles to be implementing in spatial planning and design, in order to increase the quality of environment and economic value while maintaining the visual and ecological harmony of the natural and urban environment. bučas, j. kraštotvarkinė problema kuršių nerijoje [landscaping problem in the curonian spit]. aplinkos tyrimai, inžinerija ir vadyba, 2007; 4(42): 70-80. bučas, j. kraštotvarkos pagrindai [landscaping basics]. kaunas: technologija, 2001. bučys j. daugiafunkcinių didmiesčio centrų formavimo bendrieji uždaviniai [common tasks of forming multifunctional metropolitan centers]. mokslas – lietuvos ateitis, 2009; 17-21. butkus t.s. vanduo lietuvos architektūroje [water in lithuanian architecture]. 2009; prieiga per internetą: http://www.spec.lt/lt/architektura/vanduo_ lietuvos_architekturoje. čereškevičius, s. vandens reikšmė ir įtaka tvarios urbanizuotos aplinkos formavimui [importance of water and influence on the formation of a sustainable urban environment]. urbanistinis forumas, 2013 m. spalio 25 d. kaunas. grecevičius p., godienė g. 2011 m. žvilgsnis į lietuvos kraštovaizdžio architektūrą [a glimpse into lithuanian landscape architecture]. lietuvos kraštovaizdžio įvairovė, 2/2013; kraštovaizdžio formavimo sprendimai, vilnius, 5–8. jakovlevas-mateckis k. miesto kraštovaizdžio architektūra [urban landscape architecture]. vilnius, technika”, 2008. maggie toy (ed.). architectural design magazine. architecture & water, 1/2, vol. 65, 1995, p. 7. morton h. v. the fountains of rome. the macmilan company, new york, 1966. piekienė n. kuršių nerijos kraštovaizdis. tapatybės išraiška [curonian spit landscape. identity expression]. mokslas – lietuvos ateitis, 2013; 5(3): 242–247. piekienė n. viešosios erdvės lietuvos saugomų teritorijų kūrimo kontekste [ public spaces in the context of the creation of protected areas in lithuania]. miestų želdynų formavimas. 2015 1(12) 208–215. samalavičius a. architektūra ir vanduo: žvilgsnis į idėjų ir formų istoriją [architecture and water: a glimpse into the history of ideas and forms]. archiforma, 2000, nr. 4. 66. stančius a. vandens funkcijos architektūroje: istorinis aspektas [water functions in the architecture: the historical aspect]. 2015; 181–194. stauskas v. architektūra ir gamta [architecture and nature]. 2007. prieiga per internetą: http://www. spec.lt/lt/architektura-architektura_ir_gamta stauskas v. vanduo architektūroje: kaip struktūra ir kaip elementas [water in architecture: as a structure and as an element]. archiforma, 2000; nr. 4. saugomų teritorijų įstatymas [the law of protected areas]. valstybės žinios, 2001-12-28, nr. 108–3902. želdynų įstatymas [greenery law]. valstybės žinios, 2007, nr. 80 – 3215. nacionalinė darnaus vystymosi strategija [the national strategy for sustainable development]. valstybės žinios, 2003, nr. 89–4029. lr konstitucija [constitution of the republic of lithuania]. valstybės žinios, 1992, nr. 33-1014. nijolė piekienė position at the organization klaipeda university, architecture, design and art department, k. donelaičio ave. 5, lt-92144 klaipeda, lithuania; vilnius gediminas technical university, faculty of architecture,department of architectural fundamentals and theory, pylimo str. 26/1, lt-01132 vilnius, lithuania main research area history of art address laukininkų str., 29-2, klaipėda tel. +370 687 47 505 e-mail: nijole.lin@gmail.com antanas stančius position at the organization klaipeda university, architecture, design and art department, k. donelaičio ave. 5, lt-92144 klaipeda, lithuania; vilnius gediminas technical university, faculty of architecture,department of architectural fundamentals and theory, pylimo str. 26/1, lt-01132 vilnius, lithuania main research area history of art address verkių str. 28-1, vilnius tel. +370 600 84 519 e-mail: stancius.antanas@gmail.com references about the authors journal of sustainable architecture and civil engineering 2016/2/15 38 *corresponding author: mindaugas.dauksys@ktu.lt productivity analysis of concrete slab construction by using different types of formwork http://dx.doi.org/10.5755/j01.sace.15.2.15789 gintas brazas, mindaugas daukšys*, jolanta šadauskienė, mindaugas augonis, šarūnas kelpša kaunas university of technology, faculty of civil engineering and architecture studentu str. 48, lt-51367 kaunas, lithuania received 2016/07/10 accepted after revision 2016/09/07 journal of sustainable architecture and civil engineering vol. 2 / no. 15 / 2016 pp. 38-46 doi 10.5755/j01.sace.15.2.15789 © kaunas university of technology productivity analysis of concrete slab construction by using different types of formwork jsace 2/15 in this article the influence of the panel slab, girder slab formwork and tableforms to the effectiveness of solid concrete slab construction works of multi-storey buildings is investigated. the object of investigation is 22-storey high-rise commercial residential building. the effectiveness of solid concrete slab construction works and selecting the formwork system was evaluated taking account of quality requirements, equipment ability, demand of time and labour i.e. complexity of assembling technology, universality of operation and other. three options of peri formwork systems were selected for investigation: skydeck panel slab aluminum formworks, multiflex girder slab formworks and uniportal tableforms. the rating criteria were selected for the evaluation of the effectiveness of selected formwork systems. using the pairwise evaluation method the following order of criteria importance was obtained: 17.3% – formwork rental price (k7), 16.3% – complexity of assembling technology (k3), 15.4% – machinery costs (k2), 13.9% – labour costs (k1), 13.0% – required compressive strength of concrete before formwork demoulding (k5), 12.5% – formworks demoulding time, days (k6), 11.5% – reliability of suppliers (k4). the evaluation of formwork systems, as options, according to selected evaluation criteria, was performed by topsis method and the results show that for the mounting of concrete slabs in the investigated building the rational option is to use skydeck panel slab aluminum formworks. keywords: panel slab formwork, girder slab formwork, tableforms, pairwise comparison, topsis method. conventional reinforced concrete structures are fabricated by casting concrete in temporary formwork that is usually made from timber or steel. the formwork is often held in place by temporary scaffolding. upon hardening of the concrete, the formwork and temporary support are removed, revealing the concrete structure within. in tall building construction with reinforced concrete structures, the appropriate selection of the formwork method is a crucial factor in successful project completion. the selected formwork method significantly influences the project duration and cost as well as subsequent activities. formwork systems are among the key factors determining the success of a construction project in terms of speed, quality, cost and safety of works. different types of construction require the use of different types of formworks. the strength of the building components, the speed at which building is constructed, and the cost of construction will depend to a great extent upon the approintroduction 39 journal of sustainable architecture and civil engineering 2016/2/15 priateness of formwork used in the construction. the erection of formwork is a time consuming process and cost of formwork (material+labour) could sometimes be as high as 50% of the cost of the concrete structure. efficient design of these temporary structures plays a critical role in reducing the cost and ensuring safety. formwork can be classified according to a variety of categories, relating to the differences in sizes, location of use, construction materials, nature of operation, or simply by the brand name of the products (tech mailer, 2013). major formwork systems are as follows: traditional timber formwork systems, re-usable plastic/pvc/aluminum formwork systems, table-form systems, jump form systems and slip form systems. horizontal formwork system is used to temporarily support horizontal concrete work such as concrete slabs. there are seven horizontal forming systems that can be used to support different slab types (hanna, 1998). they are: 1. conventional wood system (stick form); 2. conventional metal (aluminium) system (improved stick form); 3. flying formwork system; 4. column-mounted shoring system; 5. tunnel forming system; 6. joist-slab forming system and 7. dome forming system. formwork system for horizontal concrete work can be also classified into two main categories: hand-set system and crane-set systems. conventional wood systems and conventional metal systems are classified as hand-set systems. in hand-set systems different formwork elements can be handled by one or two labourers. flying formwork systems, column-mounted shoring systems, and tunnel formwork are classified under crane-set systems. in crane-set systems, adequate crane services must be available to handle formwork components. formwork can be a permanent part of the structural element, commonly known as stay-in-place (sip) formwork. sip formwork is often used to accelerate the construction of structural elements such as flooring, concrete bridge decks and compressed shells (hasselhoff et al 2015). authors (akmaluddin et al 2015) investigated flexural behaviour of steel reinforced lightweight concrete slab with bamboo permanent formworks. the slab specimens were achieved by fabricating the formwork using the half bamboo section and plywood. the bamboos formworks were laid on the slab bottom as a part of the permanent formwork. while teakwood were placed on the side of the slab to maintain the slab height. authors (shin et al 2012) proposed a formwork method selection model based on boosted decision trees in tall building construction to assist the practitioner’s decision making. the proposed model was compared with an artificial neural network model and a decision tree model. the results showed that the proposed model was slightly more accurate than the others in the selection of the formwork method. moreover, the result also demonstrated the advantages of the new method, i.e., single parameter setting, accuracy and stability improvement, and a comprehensible process in decision making. authors (kannan and santhi 2013) made comparison of different climbing formwork with the conventional formwork for the lift core-wall in the 20 storey high-rise building model using building information modeling (bim). results show that automatic climbing formwork systems may have additional advantages over other systems in-terms of quality and sustainability, it has considerably less safety aspect than the crane-dependent: climbing formwork systems, semi-automated formwork systems. thus, automated formwork systems are not advisable in the construction site located in the congested area, project with lack of technical sound work crew, and so on. according to authors (sharifi et al 2006) slip-forming is one of the potential concrete formwork methods that improves speed and productivity of repetitive vertical concrete work. typical projects that employ this technique are: silos, core of high-rise buildings, telecommunication towers, cooling towers, heavy concrete offshore platforms, etc. by designing optimized concrete structures, significant savings in material use can be achieved, with concomitant reductions in both embodied carbon and construction cost (orr et al 2011; journal of sustainable architecture and civil engineering 2016/2/15 40 veenendaal et al 2011). fabric formwork not only provides a simple means by which such structures can be cast, but by allowing excess pore water to bleed from the surface of the concrete the resulting element is both durable and beautiful. fabric formwork thus offers exciting opportunities for engineers and architects in the move towards a more sustainable construction industry. authors (neudecker et al 2016) work demonstrated a new technology concept for robot-assisted generative manufacturing of concrete parts. the proposed manufacturing strategies include formwork-less shotcrete application using a counter-plate guide, automatic shotcrete application for flat opposing formwork and a combined smoothing process for concrete structures. the aim of this work is to evaluate the effect of panel slab, girder slab and tableforms formwork systems on work efficiency in constructing solid concrete floor slabs in a high-rise building. a solid reinforced concrete frame for 22-storey high-rise commercial residential building was selected for the study (fig. 1a). architectural volume of the building is made of the lower and higher parts. the framing scheme of the above-ground part of the building: solid reinforced concrete columns of 650×800 mm and 500×500 mm dimensions; centre-to-centre distance between columns is 7.5 m and 5.0 m; 300-400 mm thick shaft walls of staircases, lifts and vertical mechanical chases rigidly connected by solid concrete floor slabs of 250 mm thickness and 25650×20020 mm surface area (fig. 1b). construction work efficiency in solid concrete buildings and the selection of formwork systems was evaluated taking into consideration quality requirements, equipment turnover, time and human resources, i.e. the complexity of technology, application versatility, etc. the following horizontal slab formwork systems produced by peri company and widely used in lithuanian construction projects were selected for the study: skydeck aluminum panel slab formwork, multiflex girder slab formwork and uniportal tableforms (fig. 2). design and calculation of formwork systems required to produce solid concrete floors in the analysed building were done with peri cad 18 software (fig. 2). as seen from fig. 2 b, only multiflex girder slab formwork methods fig. 1 layout of solid concrete slab 41 journal of sustainable architecture and civil engineering 2016/2/15 system is used for the entire surface area of formed solid concrete floor, whereas skydeck panel slab formwork (fig. 2 a) and uniportal modular table formwork system (fig. 2 c) are used in combination with multiflex girder slab formwork system. according to peri company (www.peri.com) with extensive range of accessories, the skydeck slab formwork is ideally suited for markets with very high safety standards. the systematic assembly sequence and lightweight system components accelerate working operations. in addition, early striking with the drophead system reduces on-site material requirements. the small prop requirements ensure more freedom of movement under the slab formwork and simplifies the horizontal transportation of materials. skydeck is generally the most cost-effective formwork system where labour is expensive, as in industrialized countries. the main components of the fig. 2 formwork systems and their overall view were designed by means of peri cad 18 software: skydeck panel slab formwork (a), multiflex girder slab formwork (b), uniportal tableforms (c) a b c journal of sustainable architecture and civil engineering 2016/2/15 42 multiflex are the vt 20k or gt 24 formwork girders. as the main and cross beams, their position and spacing as well as the form lining can be freely selected, multiflex provides maximum flexibility for a wide range of requirements. if the high load-bearing gt24 formwork girders are used, large spans for the main and cross beams can be realized. multiflex is therefore the ideal solution for complicated ground plans, slabs with offsets or integrated downstand beams, as well as forming operations in confined spaces. multiflex girder slab formwork keeps the cost of materials down. it is therefore particularly cost-effective where labour is cheap. uniportal tableforms is the ideal solution for the forming of large slab areas. for buildings with open facades, areas of up to 100 m² can be formed with this large-sized slab table. uniportal tableforms operations are always project-specifically planned. the dimensions are in accordance with the building geometry and are only limited by the maximum dead weight of the table. with the remote-controlled lifting mechanism, uniportal tableforms can be quickly and safely moved to other storeys. given sufficient crane capacity, slab tables are the most cost-effective solution where there is a high degree of repetition and open facades. the aforementioned systems were assigned to the following options: a1 – skydeck formwork system; a2 – multiflex formwork system; a3 – uniportal formwork system. the following evaluation criteria were selected for measuring the effectiveness of selected formwork systems or options: k1 – man-hours (for solid concrete slab), h/m 2; k2 – machine-hours, h/m 2; k3 – complexity of assembling technology (for solid concrete slab), points (depended on horizontal formwork system erection/demolding time (m2/h), number of elements (units/m2) and weight (kg/m2), degree of repetition and other factors); k4 – supplier’s reliability, points (not all suppliers can offer all horizontal formwork system, especially tableforms system); k5 – required compressive strength of concrete before formwork demoulding, mpa (for the same concrete and constructive scheme of building); k6 – time for formwork demoulding, days (time after that it possible demolding formwork system for the same concrete); k7 – formwork rental price, eur/m 2 per month (different horizontal formwork system have different rental price). evaluation criteria for each horizontal formwork system are different (table 1). calculations were done on the assumption that a crane was used for formwork assembling/ disassembling, delivering concrete mixture to slab forming place by the crane bucket and solid concrete slab reinforcing costs were identical in all options under evaluation. a pairwise comparison method was used to establish the relative importance of evaluation criteria. the rational option from the three analysed options was determined using the topsis method. table 1 comparison of selected horizontal formwork systems formwork system options skydeck multiflex uniportal man-hours, h/m2 0.48 0.60 0.29 machine-hours, h/m2 0.02 0.02 0.01 number of formwork system elements, units/m2 2.35 3.10 1.24 formwork system weight, kg/m2 28.78 40.00 46.10 required compressive strength of concrete before formwork demoulding, mpa ~7.0* ~19.0* ~21.0* time for formwork demoulding, days 2* 14* 14* supplier’s reliability in stock in stock need special order formwork system rental price, eur/m2 per month 12.33 5.79 12.70 * depended on different types of reinforced concrete construction. 43 journal of sustainable architecture and civil engineering 2016/2/15 the topsis method was chosen because the basic concept of this method is that the selected option should have the shortest distance from the ideal solution and the longest distance from the negative-ideal solution (antucheviciene et al 2011). results the selected values of criteria (k1-k7) that describe the options of skydeck (a1), multiflex (a2) and uniportal (a3) formwork systems are presented in the initial matrix a of alternative solutions (table 2). according to the pairwise comparison method used to determine the importance of evaluation criteria, all criteria were compared with one another in pairs (a scale of 0÷10 was chosen). for extable 2 initial matrix a of alternative solutions criteria options k1 k2 k3 k4 k5 k6 k7 a1 0.48 0.02 31.13 8 7 2 12.33 a2 0.60 0.02 43.10 7 19 14 5.79 a3 0.29 0.01 47.34 3 21 14 12.70 table 3 pairwise comparison matrix acr criteria k1 k2 k3 k4 k5 k6 k7 si qi priority order k1 4 4 6 6 6 3 29 0.139 4 k2 6 4 6 6 6 4 32 0.154 3 k3 6 6 7 4 6 5 34 0.163 2 k4 4 4 3 5 4 4 24 0.115 7 k5 4 4 4 5 6 4 27 0.130 5 k6 4 4 4 6 4 4 26 0.125 6 k7 7 6 5 6 6 6 36 0.173 1 ∑ 208 1.0    n k i i i s s q 1 , k  1,n; (1) ample, when the criteria k3 is better than the criteria k1, k3 is assigned 6 points and k1 – 4 points. when the criteria k4 is equal k5 than the above is assigned 5 points. in this manner the importance of evaluation criteria was determined (subjective importance q) according to (1) equation. to this end a pairwise comparison matrix acr was built (table 3). pairwise comparison analysis revealed the following rank of evaluation criteria by importance (subjective importance): q1 = 17.3 % ; q2 = 16.3 % ; q3 = 15.4 % ; q4 = 13.9 % ; q5 = 13.0 % ; q6 = 12.5 % ;q7 = 11.5 %. k7 – formwork rental price in eur – was found to be the most important criterion. the priority order of criteria was as follows: k7 > k3 > k2 > k1 > k5> k6 > k4. the rational option was found by means of topsis method. the initial matrix a of alternative solutions a (table 2) was supplemented by two lines: criteria optima (max or min) and the best value (x*j); consequently a new matrix of solutions was built (table 4). afterwards, matrix a was normalized (table 5). the reason for matrix normalization is that the data in initial matrix a are expressed in different units of measurement and thus are not possible journal of sustainable architecture and civil engineering 2016/2/15 44 to compare. normalization of initial matrix a produces non-dimensional values. matrix a was normalized according to (2) equation: criteria options k1 k2 k3 k4 k5 k6 k7 a1 0.48 0.02 31.13 8 7 2 12.33 a2 0.60 0.02 43.10 7 19 14 5.79 a3 0.29 0.01 47.34 3 21 14 12.70 optimization direction min min min max min min min best value 0.29 0.01 31.13 8 7 2 5.79 table 5 normalized matrix a criteria options k1 k2 k3 k4 k5 k6 k7 a1 0.584 0.667 0.437 0.724 0.240 0.101 0.662 a2 0.730 0.667 0.605 0.634 0.651 0.704 0.311 a3 0.353 0.333 0.665 0.272 0.720 0.704 0.682 table 4 alternative solutions matrix a following the normalization of matrix a, a weighted normalized matrix a* of alternative solutions is created (table 6). to this end the normalized matrix a is multiplied by the vector of criteria importance (see q1–q7 above) according to (3) equation: here: xij – i – line and j – column of matrix. (2)    j i ij ij ij x x x 1 2 , i  1,m ; j  1,n; a* = [a] · [q], table 6 weighted normalized matrix a* of alternative solutions criteria options k1 k2 k3 k4 k5 k6 k7 a1 0.101 0.108 0.067 0.101 0.031 0.013 0.076 a2 0.126 0.108 0.093 0.088 0.085 0.088 0.036 a3 0.061 0.054 0.102 0.038 0.094 0.088 0.078 the ideal best condition a+ (the best value) and the ideal worst condition a(the worst value) are found. distances between the real option ai and the ideal best condition a +, as well as between the real option ai and the ideal worst condition a are computed according to (4,5) equations: (3)    j i ij ij ij x x x 1 2 , i  1,m ; j  1,n; a* = [a] · [q], (4)     j n j iji ffl 1 , i  1,m; j  1,n;      j n j iji ffl 1 , i  1,m; j  1,n;     ii i bit ll l k , i  1,m; (5)     j n j iji ffl 1 , i  1,m; j  1,n;      j n j iji ffl 1 , i  1,m; j  1,n;     ii i bit ll l k , i  1,m; 45 journal of sustainable architecture and civil engineering 2016/2/15 the relative proximity of compared options to the ideal option is found, i.e. criterion kbit is calculated. having the criterion kbit value calculated, the priority rank of compared options is made. in table 7 data obtained by applying topsis method options li + li kbit priority order efficiency value (ni), % a1 0.127 0.209 0.622 1 100.00 a2 0.271 0.107 0.283 2 45.51 a3 0.274 0.104 0.275 3 44.28 the computation results are presented in table 7. computations done using topsis method revealed that the most rational option for the building of solid concrete floor slab in a high-rise building is option a1 – skydeck panel slab formwork system (efficiency value (ni) is 100%). option a2 – multiflex girder slab formwork system and option a3 – uniportal modular table formwork system received almost equal evaluation. respectively, their efficiency values (ni) are: 45.51% and 44.28%. this method allows to select the optimum solution of horizontal formwork system according to selected criteria system. (6)     j n j iji ffl 1 , i  1,m; j  1,n;      j n j iji ffl 1 , i  1,m; j  1,n;     ii i bit ll l k , i  1,m; our case, the best option is the one that has the highest value of criterion kbit. in the last stage the efficiency value ni of compared options is calculated according to (6) equation: 1 the effectiveness of constructing solid concrete floor slabs in high-rise buildings, namely the construction work time, price, complexity of technology and other factors can be controlled by selecting the appropriate horizontal formwork system: panel, beam and girder or modular table. 2 using the pairwise evaluation method the following order of the meaning criteria was ob-tained: 17.3% – formwork rental price (k7), 16.3% – complexity of assembling technology (k3), 15.4% – labour costs of mechanism (k2), 13.9% – labour costs of employer (k1), 13.0% – required compressive strength of concrete before formwork removal (k5), 12.5% – demoulding of formworks, days (k6), 11.5% – supplier’s reliability (k4). k7 – formwork rental price in eur – is the most important evaluation criterion. 3 computations done by means of topsis method revealed that the most rational option for the building of solid concrete floor slab in a high-rise building is option a1 – skydeck panel slab formwork system (efficiency value (ni) is 100%). conclusions references akmaluddin, pathurahman, suparjo, gazalba z. flexural behavior of steel reinforced lightweight concrete slab with bamboo permanent formworks, procedia engineering, 2015; 125: 865–872. antucheviciene j., zakarevicius a., zavadskas e. k. 2011. measuring congruence of ranking results applying particular mcdm methods, informatica, 2011; 22(3): 319-338. hanna a.s. concrete formwork system. university of wisconsin – madison. marcel dekker, inc., new york. 1998, 269 p. hasselhoff j., cheng l., waimer f., gabler m., knippers j. design, manufacturing and testing of shearcone connectors between cfrp stay-in-place formwork and concrete, composite structures, 2015; 129: 47-54. kannan m.r., santhi m.h. constructability assessment of climbing formwork systems using building information modeling, procedia engineering, 2013; 64: 1129-1138. neudecker s., bruns ch., gerbers r., heyn j., dietrich f., dröder k., raatz a., kloft h. a new robotic journal of sustainable architecture and civil engineering 2016/2/15 46 spray technology for generative manufacturing of complex concrete structures without formwork, procedia cirp, 2016; 43: 333-338. orr j.j., darby a.p., ibell t.j., evernden m.c., otlet m. concrete structures using fabric formwork, the structural engineer, 2011; 89(8): 97-105. peri company products and systems, 2016. available at: http://www.peri.com/en/products-overview.html. sharifi m.r., baciu s., zayed t. slip-form productivity analysis for concrete silos, 1st international construction specialty conference, calgary, alberta, canada, may 23-26; 2006, 1-10. shin y., kim t., cho h., kang k.-i. a formwork method selection model based on boosted decision trees in tall building construction, automation in construction, 2012; 23: 47-54. tech mailer. formwork in construction. ultratech cement. the engineers choice, 2013; 2(3): 1-7. veenendaal d., west m., block p. history and overview of fabric formwork: using fabrics for concrete casting, structural concrete, 2011; 12(3): 164-177. gintas brazas master faculty of civil engineering and architecture, department of construction technologies main research area civil engineering address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: gintas@gmail.com mindaugas daukšys dr. faculty of civil engineering and architecture, department of construction technologies main research area civil engineering, construction technology address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: mindaugas.dauksys@ktu.lt jolanta šadauskienė dr. faculty of civil engineering and architecture, department of building energy systems main research area civil engineering address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300492 e-mail: jolanta.sadauskiene@ktu.lt mindaugas augonis dr. faculty of civil engineering and architecture, department of engineering structures main research area civil engineering address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: mindaugas.augonis@ktu.lt šarūnas kelpša phd student faculty of civil engineering and architecture, department of construction technologies main research area civil engineering address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: sarunas.kelpsa@ktu.lt about the authors 5 journal of sustainable architecture and civil engineering 2017/2/19 *corresponding author: samuelebong@uniuyo.edu.ng influencing behaviour for crime prevention through architectural design and construction: an overview received 2017/03/19 accepted after revision 2017/06/21 journal of sustainable architecture and civil engineering vol. 2 / no. 19 / 2017 pp. 5-12 doi 10.5755/j01.sace.19.2.18206 © kaunas university of technology influencing behaviour for crime prevention through architectural design and construction: an overview jsace 2/19 http://dx.doi.org/10.5755/j01.sace.19.2.18206 samuel o. ebong university of uyo, faculty of environmental studies, department of architecture nwaniba road, uyo, akwa ibom state, nigeria introduction this paper discusses how architectural design could be used to manipulate the environment to influence behaviour for crime prevention. the method adopted is the review of existing literature and the qualitative approach of observation. architects are unavoidably involved in influencing behaviour of users and abusers of the built environment through their designs. the elements of architecture are subject to complete control and manipulation by the architect. architectural design for crime prevention is a design process with the explicit intention to influence behaviour. the paper maintains that in designing with the intention to influence behaviour, the designer should focus on the intended behavioural outcome in order to create a particular experience and influence user and abuser decisions. the key to designing to influence behaviour is strategic thinking. this paper therefore advocates strategic (extended) thinking as a means of arriving at a creative solution that addresses security challenges. the uniqueness of this method is that it helps the architect to understand the attacker’s methods, approaches and tactics and how to defeat them in order to create a defendable facility. it concludes that design to influence behaviour could be achieved if the architect has knowledge of crime prevention design concepts, theories and principles, the basic technology and types of crime prevention systems, products, and the process involved in integrating security and design. it recommends that architects become involved in the study of behavioural setting of a project site in order to expand the scope of programming to include and address social issues, such as crime, in their designs. keywords: influence, behaviour, crime prevention, architectural design, construction. ahmadi et al (2015) observe that the built environment influences human behaviour. they argue that its design can encourage offenders to commit crime by creating the opportunity for crime and it can prevent crime with increase of residents’ ability to monitor the environment. architects are unavoidably involved in influencing behaviour of users and abusers of the built environment through their designs. teeuw and de boer (2011) opine that the most apparent method of influencing behaviour is direct physical measures through design. arguing further, the design of the environment for effective surveillance, access control and territorial control can be used to enforce safe behaviour to counter crime. crime prevention through environmental design (cpted) is dependent on an inclusive design process involving architects, urban planners, clients, community, security experts and law enforcement professionals. its strategies are aimed at influencing a would-be offender’s decision before a criminal act (crowe and fennelly, 2013, atlas, 2013). it is journal of sustainable architecture and civil engineering 2017/2/19 6 focused on manipulating the built environs to deny criminal opportunities by increasing the risk and reducing the ease and reward factors. this is based on the premise that the environment emits some cues that influence the offenders’ target selection process. it is also intended to make citizens feel safer by reducing the fear of crime. a study by pirbasti et al (2015) indicate that design can create “an environment that can encourage normal behaviour and discourage unwanted ones.” however, a different perspective suggests that criminal adaptation to anti-crime design measures diminishes the ability of “environmental factors to influence behaviour thereby questioning the cpted premise of using design to influence criminal behaviour” (mckay, 2015). it raises the question: how can design be used to address criminal adaptation and behavioural change? schneider et al. (2013) drawing from experiences from a research-based design studio suggest that building designs require that architects consider future users and try to predict the likely pattern of use and abuse of a building. this paper agrees that design should, therefore, evolve to address new criminal behaviour as it relates to tactics, tools and weapon since, as observed by mckay (2014), “human behaviour is not static but always evolving.” the key, therefore, is to apply strategic thinking during the design process as a means of arriving at solutions that address the security challenges. strategic thinking involves thinking outside the usual architectural box to find solution to crime prevention and intricate security challenges. it involves designing with the holistic understanding of the potential threats and risks to a proposed facility. for example, from 1934 – 1945, the japanese army needed to construct underground inter-connected fortresses along chinese-russian border in north east china to accommodate hundreds of thousands of military personnel and several arms and food storage facilities. the challenge to the architect and the design team was not only the design of such massive underground facilities but lighting, sanitary and ventilation systems and most importantly entrances and exits that could not be detected or discovered. in order to solve this intricate security challenge the design team had to think strategically in military and security terms. this was accomplished and some of the fortresses were discovered only at the end of the chinese-japanese war in 1945. different types of construction and their application in different combinations were used. strategic thinking involves understanding the attackers’ methods and how to defeat them. such methods include moving and stationary vehicle bombs, suicide bombers, use of petrol bombs, grenades, standoff weapons such rocket propelled grenades (rpgs), use of light arms, assault rifles and high-powered sniper rifles. it also includes use of special cutting equipment and blow touches to create man-passable holes, clandestine entry, tail gating and sometimes the use of chemical and biological weapons. this calls for more than basic security design thinking of fence, burglary proof, security doors and installation of close-circuit television. it calls for thinking creatively and strategically in order to create a defensible facility that minimises opportunities for the threat to manifest. the products of architecture by implication must not only be beautiful and of sound construction but must have intellectual content. great architectural works, principles and theories have always generated great discourse and debates because of their ability to draw from and build upon precedents and other fields of study. the basic elements of architecture are subject to complete control by the designer. as an artist, the architect decides the precise shape, size and proportions of a building, roof, columns and walls and spaces. as a scientist he engages technology in adapting these elements. for example, artificial light can be controlled to achieve different effects on the building elements, spaces and people. it can be used as a security element to create deterrence effect. other building materials can have their texture, strength and qualities elaborately improved and enriched through technology to achieve different purposes, including crime prevention. this paper discusses how architectural design and construction elements could be used to manipulate the environment to influence behaviour for crime prevention. 7 journal of sustainable architecture and civil engineering 2017/2/19 two methods are adopted for this work. first is the review of literature to help situate the paper. secondly, the qualitative method of observation is used to help to practically support the concepts. the observations were documented as photographs. qualitative data is more concerned with meanings and also enables the use of literature as an important source in helping to find probable clarifications of the phenomenon of study (o’conor and gibson, 2003). methods influencing behaviour through design architectural design begins with the site. the site is a crucial aspect of environment. it communicates challenges and opportunities, limits what can be done on it and also opens new possibilities. the site is the first contact that one has with any architectural project before one can access the building. therefore, in planning and designing the site for security the following should be considered, namely, placement of structures on the site, location of functions and shaping the spaces in order to influence behaviour and achieve the objectives of the project. architectural design is the process of deliberately creating and shaping spaces. flusty (1997) sees crime prevention design as the process of creating ‘interdictory spaces’ to influence behaviour. these are spaces designed to intercept and ward off or screen and sort out would be users. he identifies five types of interdictory spaces as follows: (i) stealthy space – areas deliberately hidden from general view; (ii) slippery space – those without visible means of approach; (iii) crusty space – those that cannot be accessed because of obstruction; (iv) prickly space – uncomfortable space due to measures inhibiting activities; and (v) jittery space – space under constant observation, both positive and negative. the choice and design of these spaces depend on the design and security objectives which in turn depend on the purpose of the project and the risk profile of the users. all buildings create social activity due to their proposed function, interactions and the sometime random encounters that they generate. the planning and design of activity and circulation spaces can encourage or hinder interaction which can occur at any number of points. the architect or designer can decisively control the extent that he designates the points of contact or interaction. this involves broad strategies and specific tactics which can be expressed architecturally. practically, most behaviour influencing architectural patterns involve the physical arrangement of internal and external building elements and/or a change in material properties (lockton, 2011). arrangements, positioning and layout of spaces and building elements are crucial in determining the kind of behaviour to influence. for example, barriers could be put in people’s way to hinder access to a particular area; pedestrian or vehicular traffic could be channelled or directed in a particular direction by strategic placement of site elements and surveillance could be enhanced by strategic placement of windows, openings and location of trees. it is necessary for architects to aspire to produce buildings which are not only attractive, functional and up-to-date but that can influence positively user attitudes and behaviours. the crime prevention architectural design process can be driven by the following, individually and collectively: (i) explicit intention to influence behaviour, (ii) behaviour consequences revealed by design decisions made in previous projects, and (iii) impacts of previous projects on crime. in designing with the intention to influence behaviour, the designer should focus on the intended behavioural outcome, for strategic reasons, in order to create a particular experience and influence user decisions. architectural design for crime prevention is a design process with the explicit intention to influence behaviour that draws from previous design decisions and projects. seven steps are required in order to design to influence behaviour for crime prevention. these are, establish and analyse the client’s brief in terms of goals and objectives, define the problem, analyse site, analyse users, carry out design programming, specify and incorporate appropriate products and mechanisms, and develop final design. in defining the problem several questions should be asked and answered: where is the project to be located? what is the purpose of the project? what are the objectives of the project? who are the users? what are the requirements? what resources are available? what is the expected solution or design outcome? in analysing the site, the essential character of the site and patterns of activities journal of sustainable architecture and civil engineering 2017/2/19 8 (legitimate and illegitimate) in and around it should be carefully considered. it is also necessary to analyse the users to understand the risk pattern of the users. in every facility there are risk to users and risk from users. according to atlas and hopper (2007), the basis for a creative security design is an accurate risk assessment. in the formal design process programming is more concerned with the technical aspects of the pre-design investigations such as site, spatial, cost and regulatory analysis. little is done in investigating behavioural settings, such as crime, that can best address real human needs, conditions and requirements. according to horayangkura (2012), programming provides the opportunities to incorporate the necessary information inputs of the users and social context of the design. programming for design requires an analysis of existing projects (case studies) for success patterns, population profile, site usage, package of activities, constraints, failures of physical arrangements and performance. listed objectives should be translated into performance statements, requirements and design assumptions. the identified problem should be framed from different perspectives with the help of experts (security, engineering, law enforcement). incorporating the 4ds of crime prevention into design to influence behaviour security design is the process of incorporating a project’s crime risks, vulnerabilities, security measures required and an assessment of where these measures are required into the design. a good and pro-active security design must address the 4ds of crime prevention deter, delay, detect, and deny access for unauthorised entry. deterrence is a psychological approach that is directed at the decision-making process of the criminal with the intension of making him/her to decide against a criminal act. deterrence in security functions through the concept of fear-changing behaviour through the fear of being apprehended and punished. fear strongly affects human behaviour and the fear of punishment has a strong sobering effect on an individual’s survival instinct. this concept of fear has been used variously by parents, schools, religion and governments, when necessary, to produce an expected form of behaviour. many of the physical measures adopted have psychological effect. lighting is a physical security measure which cannot stop crime. it aids surveillance. a well-lit environment registers in the mind of an intruder that the chances of being seen and caught is higher than in poorly lit environment. a number of studies carried out in a variety of settings indicate that there is ample evidence that improved street and external lighting are effective in reducing property crime significantly (welsh and farrington, 2006, 2009). various other means such as physical barriers, access control, cctv, fences, doors and warning signs attain this effect. available evidence also suggests that the effectiveness of cctv in deterring crime depends on the extent to which peofig. 1 these bank building access control doors in abuja, nigeria promote deterrence, delay and detection. photograph by the author ple are aware of its existence (mclean et al., 2013). fig.1 shows a building access control mechanism. this mechanism allows only one-person access at a time. it is configured to detect metals and therefore is useful for screening people for weapons as the inner door does not open when a metal is detected. this enables the security personnel to search the person if it becomes necessary. it acts as both deterrence and delay measure. delay is another principle of 9 journal of sustainable architecture and civil engineering 2017/2/19 crime prevention which gives security personnel the needed time to respond to a threat situation. the design principle is to increase the effort and make it more difficult for the intruder to commit the crime. one strategy to attain delay is to provide different layers of security working together to create a defence depth. physical security practitioners have identified three lines of defence. these are the site perimeter as the first line of defence, the outer building walls as the second line of defence and the internal building spaces as the third line of defence (federal emergency management agency, 2007; atlas and hopper 2007). perimeter control is achieved through the use of fence, wall, guards, gates and closed circuit television. the perimeter should be well defined to make it distinguishable to both legitimate users and intruders thereby creating zones of influence (fig. 2). the establishment of a hierarchy of spaces (zoning) can also help to achieve an effective layer of defence to accomplish the principle of delay. properly designed and designated zones will allow proper levels of physical and psychological controls based on the risk and vulnerability assessments. for zoning to be effective risks to and from a particular group of users should be determined. movement pattern of each risk-categorised user group should be traced. for example, employees require less degree of control and verification than visitors. access control which is a method of defig. 2 solid block wall fence used to delineate public and private zones in a residential neighbourhood in abuja, nigeria. photograph by the author lay in physical security should be carried out at designated areas. design can channel users to these security screening points which are points of transition from one zone to another. the numbers of these transition points depend on site layout, positioning of building and interior space function and layout. vehicular access control measures are shown in fig. 3. it shows how vehicle speed control mechanisms are combined with fig. 3 comprehensive vehicle access control system. scheme by the author journal of sustainable architecture and civil engineering 2017/2/19 10 vehicle arrest mechanisms to form a comprehensive access control system. fig. 4 shows the entrance gate to united nations house, abuja brought down by a bomb-laden vehicle driven by a suicide bomber before ramming into the building. this was made easy because there was no vehicle access control system to slow down and stop the vehicle before it got to the gate. the gate may not have been crash-rated to stop any type of vehicular assault on it. this is evidenced by the way the gate was easily brought down. detection is achieved through careful and close monitoring and observation of an area or a target through the use of human and technological devices such as closed-circuit television, sensors and alarms and other surveillance techniques. good design can greatly enhance surveillance by enhancing clear and unobstructed lines of sight which is a fundamental requirement for effective surveillance (fig. 5). poor design can create blind spots that can aid the compromise of security (fig. 6). every property (building and site) is made up of two major components. these are activity areas and linkages. activity areas are areas provided for users to carry fig. 4 the gate to united nations house, abuj brought down by a bomb-laden vehicle before ramming into the building. note that there is no vehicle access control system (marama, 2011) fig. 5 gate house to akwa ibom state house of assembly, uyo, nigeria. the windows allow observation of areas outside the gate with clear lines of sight. photograph by the author fig. 6 gate house in high court complex, moore road, calabar, nigeria shows design and construction without windows and/ or openings for natural surveillance of road and parking areas thereby creating blind spots that could lead to security compromise. photograph by the author out designated functions while linkages are the paths, routes and connections between these user function areas. the alignment and positioning of activity areas and linkages greatly affect the lines of sight need for effective surveillance. sight lines can also aid negative or hostile surveillance. this allows criminals lines of sight to a potential target or targets. elevated sites may allow observation and monitoring of lower areas by adversaries. lines of site can be blocked to avert hostile surveillance using design elements. cctv is the most commonly used mechanical method of detection. a study by levesley and martin (2005) suggests that instead of preventing crime its strength lies in its capacity to “proactively detect crime incidents” when monitored real time. the ultimate aim of physical security is to deny access to would-be assailants. this is done by human and physical means. guards provide the human means of denying access to intruders. 11 journal of sustainable architecture and civil engineering 2017/2/19 barriers are the physical means that enhance the defence of a property. barriers function by target hardening of vulnerable areas (fig. 7) and by channelling users away from unauthorised areas to designated control points. barriers vary according to intended security usage and function. there are three main types of barriers, namely: vehicle, people and screening barriers. vehicle and people barriers restrict movement to only designated areas while screening barriers such fig. 7 metal burglary proof entrance door used as target hardening measure to provide delay and denial of unauthorised access to classrooms in a health institution in calabar, nigeria. photograph by the author fig. 8 engineered planters and metal fence used to restrict vehicular access and channel pedestrian traffic to access point at a school in abuja, nigeria. photograph by the author as fences, walls and tall planting (hedges and shrubs) prevent potential offenders from gathering information to aid their operations. according to brodie (2005), barriers are effective in shielding a target from observation by criminals, in deterring, delaying or stopping an aggressor, or in mitigating the force, strength and severity of an attack. barriers can aid circulation and channel traffic (fig. 8), serve as obstacles and aid in controlling vehicular speed. it can also help to decrease the kinetic energy of a vehicle, especially vehicles with explosive devices. the use of blast resistant doors, windows and other building structural members decreases damage to property and loss of life due to explosion. effective barrier deployment and placement can only be done in tandem with the overall security objectives which take into consideration the risks and vulnerability assessments of the building, site and users. this paper drew attention to the fact that the design of the built environment has the capacity to influence behaviour either positively or negatively. it noted that in influencing behaviour for crime prevention the architect needs to consider criminal adaptation to existing methods and adopt strategic measures to stay ahead of the criminal. architects can use the defensible space concepts of territorial control, access control and surveillance, among other methods, to enforce behaviour that can counter crime. the design and layout of spaces and the physical arrangement of site and building elements is the key to influencing behaviour for crime prevention. the goal of the architect should be to design secure and safe buildings. this can only be carried out effectively if the architect has knowledge of crime prevention design concepts, theories and principles, the basic technology and types of crime prevention systems and the process involved in integrating security and design to influence behaviour. this paper recommends that architects become involved in the study of behavioural setting of a site in order to expand the scope of design programming to include and address social issues in their designs. further research is needed on ways to counter criminal adaptation. conclusions journal of sustainable architecture and civil engineering 2017/2/19 12 atlas r. 21st century security and cpted: designing for critical infrastructure protection and crime prevention. boca raton: crc press; 2013. https://doi. org/10.1201/b15046 atlas r., hopper l. j. security considerations: crime prevention though environmental design. in landscape architectural graphics standards (students ed.). hopper, l. j. 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(ed.), architecture of fear. princeton: architectural press; 1997. o’conor h., gibson n. a step-by-step guide to qualitative data analysis. pimatiziwin: journal of aboriginal and community health, 2003; 1(1): 63 – 91. horayangkura v. incorporating environment-behaviour knowledge into the design process: an elusive challenge for architects in the 21st century. procedia – social and behavioral sciences, 2012; 50: 30 – 41. https://doi.org/10.1016/j.sbspro.2012.08.013 levesley t., martin, a. police attitude to and use of cctv. home office on-line report 09/05, 2005; retrieved from https://www.homeoffice.gov.uk/rds/ pdfs05/rdsolr0905.pdf lockton d. architecture, urbanism, design and behaviour: a brief review, 2011; retrieved from www. danlocton.co.uk marama n. un house bombing: why we struckboko haram, 2011; retrieved from http://www.vanguardngr.com/2011/08/un-house-bombing-whywe-struck-boko-haram/ mckay t. focusing on behaviour will benefit design, 2015; retrieved from https://www.publicsafety.gc. ca/cnt/rsrcs/lbrr/ctlg/ mclean s. j., worden r. e., kim m. here’s looking at you: an evaluation of public cctv cameras and their effects on crime and disorder. criminal justice review, 2013; 38(3): 303 – 334. https://doi. org/10.1177/0734016813492415 pirbasti m. y., azari a. r. and shirchi f. the influence of urban design in preventing and reducing the amount of crime and raucousness and the delivery of sense of security (lalijan as a case). current world environment, 2015; 10 (1): 474 – 483. schneider s., kuliga s., hölscher c.,conroy-dalton r., kunert,a., kulik a., donath d. educating architecture students to design buildings from inside out: experiences from a research-based design studio. in, kim y.o., park h. t., seo k. w. (eds), proceedings of ninth international space syntax symposium. seoul: sejong university; 2013. teeuw w. and de boer j. influencing behaviour for safe working environment. enschede, the netherlands: saxon research centre for design and technology; 2011 welsh b. c. and farrinton d. p. cctv and street lighting: comparative effects on crime. in, perry a. e., mcdougal c. and farrington d. p. (eds), reducing crime: the effectiveness of criminal justice interventions. chichester: john wiley; 2006. welsh b. c. and farrinton d. p. (2009). public area cctv and crime prevention: an updated systematic review and meta-analysis. justice quaterly, 2009; 26(4): 716 – 745. https://doi. org/10.1080/07418820802506206 about the author references samuel o. ebong lecturer department of architecture, faculty of environmental studies main research area construction management; anti-terrorism, crime prevention and security design address university of uyo, uyo, nigeria tel: +2348023144366 e-mail: samuelebong@uniuyo.edu.ng 21 journal of sustainable architecture and civil engineering 2015/2/11 jsace 2/11 journal of sustainable architecture and civil engineering vol. 2 / no. 11 / 2015 pp. 21-31 doi 10.5755/j01.sace.11.2.10291 © kaunas university of technology received 2015/02/02 accepted after revision 2015/06/01 lca as comparative tool for concrete columns and glulam columns gámez-garcía diana carolina universidad politécnica de cataluña, escuela técnica superior de arquitectura de barcelona av. diagonal, 649-651, 08028, barcelona, spain gómez-soberón josé manuel* universidad politécnica de cataluña, escuela politécnica superior de edificación de barcelona av. doctor marañón, 44-50, 08028, barcelona, spain corral-higuera ramon, almaral-sánchez jorge luis universidad autónoma de sinaloa, facultad de ingeniería mochis fuente de poseidón y ángel flores s/n pte., 81223, los mochis, sinaloa, mexico gómez-soberón maría consolación universidad autónoma metropolitana, facultad de ingeniería civil av. san pablo no. 180. col. reynosa tamaulipas, 02200. delegación azcapotzalco. distrito federal. mexico gómez-soberón luis alberto alonso y asociados, distrito federal. mexico *corresponding author: josemanuel.gomez@upc.edu lca as comparative tool for concrete columns and glulam columns http://dx.doi.org/10.5755/j01.sace.11.2.10291 nowadays, in the construction sector, some methods are being investigated to detect and minimize their environmental impact. the life cycle assessment (lca) is a tool that allows the evaluation of the environmental burden of a product or process, with a scientific recognition increment; and therefore the aim of this work is to verify the feasibility of the use of lca in the construction sector. for this purpose, the environmental impacts of the use of conventional reinforced concrete (rc) columns, and glulam (g) as an alternative material, were compared. the scope of the lca included the extraction and manufacture of materials and construction of the columns; the software tools used were lca manager 1.3 and database ecoinvent 2.0. the study showed that the most critical stage is the production of materials. rc reports 3.5 times more damage to ecosystem quality, requires a 32% more extraction of natural resources, and produces effects on human health 53% higher than g; while g generates 108 times more damage to land occupation; however, considering environmental measures, this effect can be mitigated, since it is a material 100% renewable. finally, it was verified that lca is a feasible option to use in the construction field and, it provides a wide range of results. keywords: glulam, lca, reinforced-concrete, sustainable-construction. journal of sustainable architecture and civil engineering 2015/2/11 22 the construction sector transforms the environment with important consequences and impacts on it. it is responsible for high-energy consumption, 30-40% of total worldwide energy (ortiz et al. 2009, erlandsson and borg 2003, kellenberger and althaus 2008, ramesh et al. 2010, xing et al. 2008, carvalho-filho 2001). it is also a waste generator; an emitter of greenhouse gases, 40% of total emissions (ramesh et al. 2010, carvalho-filho 2001); responsible for environmental damage; and consumer of natural resources, 40% on a global scale (ortiz et al. 2009, erlandsson and borg 2003, kellenberger and althaus 2008, ramesh et al. 2010, o´reilly-díaz et al. 2010, xing et al. 2008, zhang et al. 2006, carvalho-filho 2001). the implementation of reduction strategies (in energy demand, material consumption and waste generation, effluents and emissions generation) may be alternatives to mitigate these problems. however, it is necessary to unite criteria and channel them to a single address: sustainability. lca of materials is the current tool, which is been implemented for this purpose. in some previous studies (ortiz et al. 2009), there is evidence of its use in the construction sector since the 90s with satisfactory results. in spite of the fact that lca is a promising tool to improve the sustainable aspect of the construction sector, it still requires further studies. for example, peuportier (2000) concluded that using the lca as evaluative tool is still difficult, due to the lack of information. while more recently, ortiz et al. (2009) concluded that the use of lca is very important to minimize the environmental impact, improving the sustainability indicators. for what, khasreen et al. (2009) carried out a review about the lca in construction, concluding that despite the limitations that still exist, lca is a powerful tool for the evaluation of environmental impact of buildings. one limitations of the lca in construction is the lack of specific life cycle inventory (lci) in each region or sector, especially in developing countries. the development of specific inventory of each area is necessary, for example, in spain there is not an exclusive database, so that in some studies, such as this, the importance of creating local inventories with specific information is emphasize. althaus et al. (2005), analyzed the swiss database ecoinvent (lci based on swiss and european generic data). while bilec et al. (2006) proposed a hybrid model of lca and analyzed existing models. both concluded that the creation of local, current and specific lci in each geographical region and construction area is necessary. moreover, although the operation phase is the most representative in the environmental impact of buildings, approximately 80-90% of the entire lifecycle (cabeza et al. 2014, khasreen, banfill and menzies 2009, ramesh et al. 2010, radhi and sharples 2013, utama et al. 2012), the construction (and pre-construction) phase should not be neglected for its high environmental impact and because the energy efficiency of the operation stage depends on it. it can also provide positive impacts at the end of the life cycle, considering potential return materials to new lifecycles. according to the above, studies have been carried out to identify the impacts of the different stages in the life cycle. venkatarama et al. (2003) studied about embodied energy, concluding that the use of alternative materials and high-energy efficiency is very important for the environment. meanwhile, horvath et al. (2005) when studying the construction and pre-construction phase (stage of embodied energy) of buildings, concluded that the environmental effects can be mitigated carefully selecting the primary materials, secondary materials and construction equipment. in the same year pérez-garcía et al. (2005), found that woodland materials generate a high reduction in atmospheric carbon emissions in housing construction. similarly rivela et al. (2006) suggested promoting the use of renewable energies and materials to avoid damage to natural resources. in the same subject asif et al. (2007), evaluating the embodied energy of materials, found that concrete consumes more energy than wood. zabalza et al. (2009) proposed and implemented a simplified lca methodology and concluded that energy certifications must consider the use of renewable and recyclable materials, among other technologies. aye et al. (2012) found that the use introduction 23 journal of sustainable architecture and civil engineering 2015/2/11 of prefabricated materials (such as modular steel and wood) is an option with environmental advantages because it incorporates broader life cycles. dodoo et al. (2014) showed that wood-building systems could contribute to improve the resource efficiency in the buildings construction. the main objective of the research is to verify the feasibility of the use of lca as an evaluative tool in the construction of typical structural elements of a building, in this case, columns. the structural elements are analyzed considering two alternative materials: rc and g, both with capacity to resist structural loads and durability. characteristics of the study sample for this research, a typical attached housing is used, evaluated according to the protocols of the standards iso 14040 for lca (2006). the property is located in 41º40’ 5.24” n, 02º1.5’20.03’’ e, municipality of l’ametlla, barcelona, spain. it is a three-storey building, with 60 columns (basement b, ground floor gf, and plant type pt), its general details are presented in table 1; likewise, the quantities of material used to manufacture the columns (considering a density to the rc of 2400 kg/m3, and a density to the g of 410 kg/m3) are indicated. the general details of the sections evaluated equivalent for both cases are presented in fig. 1. methodology table 1 general details of the columns fig. 1 a) column section of rc (cm) b) column section of g (cm) l ev el n o. c ol um n h ei gh t ( m ) rc g column dimension (cm x cm) quantity column dimension (cm x cm) quantity (ton) (m3) (ton) (m3) b 6 2.3 30x30 2.98 1.2 27x24 0.36 0.9 gf 33 2.8 20.00 8.3 2.45 6.0 pt 21 3.6 16.50 6.9 2.01 4.9 characteristics of the study sample for this research, a typical attached housing is used, evaluated according to the protocols of the standards iso 14040 for lca (2006). the property is located in 41º40� 5.24” n, 02º1.5'20.03'' e, municipality of l'ametlla, barcelona, spain. it is a three-storey building, with 60 columns (basement b, ground floor gf, and plant type pt), its general details are presented in table 1; likewise, the quantities of material used to manufacture the columns (considering a density to the rc of 2400 kg/m3, and a density to the g of 410 kg/m3) are indicated. the general details of the sections evaluated equivalent for both cases are presented in fig. 1. table 1. general details of the columns. l ev el n o. c ol um n h ei gh t ( m ) rc g column dimension (cm x cm) quantity column dimension (cm x cm) quantity (ton) (m3) (ton) (m3) b 6 2.3 30x30 2.98 1.2 27x24 0.36 0.9 gf 33 2.8 20.00 8.3 2.45 6.0 pt 21 3.6 16.50 6.9 2.01 4.9 fig. 1. a) column section of rc (cm) b) column section of g (cm). the study sample consists of two attached homes designed as a single volume, both have identical dimensions and characteristics (together 446 m2 of floor area), share an intermediate wall (including columns and beams) and the parcel where are located is 27 m x 39 m, 1053 m2. each dwelling has an average occupation capacity for six people and the set is located 33 km from the catalan capital. the project satisfies the basic requirements of spanish and catalan legal framework, listed in table 2. table 2. legal framework of the project normative section description technical building code (cte) article 3 of law 38/1999 db-hr noise protection. db-hs health. db-si safety in case of fire. db-se structural safety. db-sua safety in use and accessibility. the study sample consists of two attached homes designed as a single volume, both have identical dimensions and characteristics (together 446 m2 of floor area), share an intermediate wall (including columns and beams) and the parcel where are located is 27 m x 39 m, 1053 m2. each dwelling has an average occupation capacity for six people and the set is located 33 km from the catalan capital. the project satisfies the basic requirements of spanish and catalan legal framework, listed in table 2. the building structure contains a self-supporting unidirectional slab with semi-joists of rc, beams and columns of rc. it has spread and isolated footings in foundation. table 3 shows the description of the structural elements. g was used as an alternative material, gl28c resistant class, of fir tree with melanin glue for interior columns and resorcinol glue for exterior columns, with a compressive strength parallel to the fibers of 24 mpa and flexural strength of 28 mpa. journal of sustainable architecture and civil engineering 2015/2/11 24 table 2 legal framework of the project table 3 details of structural elements of housing element constructive description columns rc**, steel* with free height up to 3 m, amount of steel 120 kg/m3, longitudinal reinforcement 4 ø16 and stirrups #10@20. foundation slab in b and part of the gf, thick 25 cm, rc**, reinforcement electrowelded mesh (me) lower and upper ø5 15x15 mm, steel* and compression layer 4 cm. spread footing rc**, steel* amount of 70 kg/m3. isolated footing rc**, steel* amount of 57.853 kg/m3. basement wall. formwork two sides, h ≤ 3 m., rc**, steel*, thick 30 cm and industrial finish. tie beams rc**, steel* amount of 77.137 kg/m3. slabs of scale rc**, steel* amount of 30 kg/m2, and thick 20 cm, wood framing and concrete staggered. slabs structure of rc**; volume of concrete 0,173 m3/m2; steel*total amount of 16 kg/m2; unidirectional slab 30 = 25 + 5 cm; semi-joists prestressed; concrete slab, 60x20x25 cm; me 20x20, ø 5 mm, steel* 6x2,20 in compression layer; flat beams. note: * une-en 10080 b500s, **ha-25/b/20/iia normative section description technical building code (cte) article 3 of law 38/1999 db-hr noise protection. db-hs health. db-si safety in case of fire. db-se structural safety. db-sua safety in use and accessibility. db-he energy savings. ehe-08 fulfilment of requirements de rc rebt low voltage electrical regulations, royal decree 842/2002 of the 2 august 2002. rite rules of installation: thermal installations in buildings, royal decree 1027/2007. decree 68/2010: processing and approval of documents recognized of the technical building code. decree 135/1995 accessibility code of catalonia. decree 21/2006 adoption of environmental criteria and eco-efficiency in buildings. municipal level general urban plan (01/14/1987) goal and scope of the lca the objective of the analysis is to compare the environmental impact between rc columns and g columns, for a dwelling. the study was conceived from a design point of view, in order to help the constructor and the designer to take assertive decisions about the most favorable choice of two types of columns, before construction. the software used was lca manager 1.3, which allows evaluating, quantifying and qualifying all employed resources, managing waste, discharges and emissions throughout the system, 25 journal of sustainable architecture and civil engineering 2015/2/11 fig. 2 system of lca of the construction of columns g was used as an alternative material, gl28c resistant class, of fir tree with melanin glue for interior columns and resorcinol glue for exterior columns, with a compressive strength parallel to the fibers of 24 mpa and flexural strength of 28 mpa. goal and scope of the lca the objective of the analysis is to compare the environmental impact between rc columns and g columns, for a dwelling. the study was conceived from a design point of view, in order to help the constructor and the designer to take assertive decisions about the most favorable choice of two types of columns, before construction. the software used was lca manager 1.3, which allows evaluating, quantifying and qualifying all employed resources, managing waste, discharges and emissions throughout the system, with the limitations of border specified. the system has been limited to the pre-construction (extraction of raw materials and production) until the construction of the columns, this because, these stages allow to identify the most important affectations with whom the columns contribute in the system. fig. 2 presents the schema of the system used. fig. 2. system of lca of the construction of columns. lca is a methodology that allowed evaluate the environmental burdens of products and processes (goods and services) during their life cycle, achieving apply the concept of sustainability from the analysis that goes "cradle to grave" (ortiz et al. 2009, erlandsson and borg 2003, o´reilly-díaz et al. 2010, xing et al. 2008, zhang et al. 2006, carvalho-filho 2001, simpple 2010). the description of the methodology is based on international standards iso 14040 series (13), which consists of four different analytical steps: defining the goal and scope, inventory creation, impact assessment and finally the interpretation of results; being the final report, the last element that completes the phases of lca (ortiz et al. 2009, carvalho-filho 2001, simpple 2010). as functional unit was selected the m3 of material employed in the fabrication of the columns, the foregoing by the fact that these have different sectional dimensions (the difference in the physical, with the limitations of border specified. the system has been limited to the pre-construction (extraction of raw materials and production) until the construction of the columns, this because, these stages allow to identify the most important affectations with whom the columns contribute in the system. fig. 2 presents the schema of the system used. lca is a methodology that allowed evaluate the environmental burdens of products and processes (goods and services) during their life cycle, achieving apply the concept of sustainability from the analysis that goes “cradle to grave” (ortiz et al. 2009, erlandsson and borg 2003, o´reilly-díaz et al. 2010, xing et al. 2008, zhang et al. 2006, carvalho-filho 2001, simpple 2010). the description of the methodology is based on international standards iso 14040 series (13), which consists of four different analytical steps: defining the goal and scope, inventory creation, impact assessment and finally the interpretation of results; being the final report, the last element that completes the phases of lca (ortiz et al. 2009, carvalho-filho 2001, simpple 2010). as functional unit was selected the m3 of material employed in the fabrication of the columns, the foregoing by the fact that these have different sectional dimensions (the difference in the physical, mechanical and elastic characteristics of the rc and g). the first of these (rc) is considered conventional in the construction of housing, while the second (g) is an alternative; for this research, both materials are comparable as vertical structural elements. use m3 as comparable unit, permits to unify and to simplify the comparison between them, in addition to being feasible for using in others investigations of structural elements, despising the dimensions of the columns (height and section). moreover, common used functional units, such as m2, are not feasible to use in columns because its distribution in the construction is not uniform (unless to carried out the lca for all building elements and systems). for the case of linear meter, this is not representative (for differences in the dimensions of the columns and their physical characteristics). with regard to materials of study, rc was selected for its high environmental affectation since it requires significant amounts of non-renewable materials and produces high power consumption for its constitution and manufacturing (ortiz 2009, gaimster and munn 2007, deshpande 2011, xiao et al. 2012); so it is necessary to study alternatives to it. among the possible options, replace it with an alternative material (g) seems more appropriate than the partial substitution of the constituent materials (fly ash, blast furnace slag and silica fume by cement; and recycled aggregates by natural aggregates). in accordance with the foregoing, some action plans for climate have been established, proposing the use of wood in construction as a mitigation measure of emissions and combat for climate change (gobierno-vasco 2009). these ones indicate that the use of g panels can save energy by 35% during the life cycle, and reduce 97% in co 2 emissions compared to traditional rc and steel frames structures (fernández et al. 2014); thus allowing obtains a primary energy balance with an more basic life cycle (dodoo et al. 2014). journal of sustainable architecture and civil engineering 2015/2/11 26 inventory analysis ecoinvent v2.01 (2007) database was used for the inventory in this study. this database has been developed by swiss technology (ortiz, castells and sonneman 2010), and consist on swiss data and in some cases on average european data (ecoinvent 2015). despite this, ecoinvent has been selected due to limited inventory information found in the spanish sector and, specifically in the construction area. given this limitation, only data from the european average were selected (generic data, no swiss data). the project data were quantified from the amounts of reinforced concrete (compressive strength 25 n/mm2) required for preparation of the columns (table 1), and considering an amount of steel 120 kg/m3. similarly, the amounts for the g of the proposed alternative design were determined, considering glued laminated timber of indoor use (for indoor columns) and outdoor use (for external columns) of six layers (45 cm each). in the lca manager 1.3 were entered these data, for the calculation and analysis of results. ecoinvent (2015) is the database world leader and the most used as a lci, being recognized for having consistent, transparent and timely data; contains international information of lci for the supply of energy, resource extraction, and supply of materials, use of chemicals, metals, agriculture, services, waste management and transport. this database is used by 4,500 persons in over 40 countries and is included in many of the leader tools of lca software (such as lca manager), as well as several tools of eco-design for construction, waste management or product design (ecoinvent centre 2015). environmental impact analysis the environmental impact assessment was performed using the lca manager 1.3, a tool for environmental assessment based on the methodology of lca (iso 14040/44: 2006) for industrial products and processes, created by simpple (2010). this tool supports the eco-innovation and allows to quantify and communicate the environmental profile of products and/or processes taking into account their entire life cycle (it can be compared by its function with tools like simapro, bees, gabi). the calculation through lca manager, is carried out by six stages of calculation: characterization, inventory, indicators, impacts, results and graphs (simpple 2010). the impact categories studied in this research refers to the energy consumption, natural resources and emissions resulting from the processes of each material used and its impact on the environment. these categories are the most representative in the stages studied (extraction, production and construction), also are included in the eco-indicator99, method that was selected due to its wide use and recognition in europe, and included in lca manager 1.3. the eco-indicators 99 selected for the lca, permits to study and report the effects of the investigated processes (rc and g) in the following sections: 1 ecosystem quality (acidification-eutrophication, eco-toxicity and land occupation). 2 natural resources consumption (mineral extraction, and fossil fuels consumption). 3 health (climate change, ozone layer depletion, ionizing radiation, respiratory effects or car-cinogenic). eco-indicator 99 is a method of environmental impact assessment, which weights the study to highlight the environmental damage, modeling the resource use and emissions effects on human health, considering the quality of the ecosystems and consumption of natural resources. finally, the impact on these three security parameters are weighted to provide an indicator with a single component (kellenberger and althaus 2009), which allows grouping and comparing. 27 journal of sustainable architecture and civil engineering 2015/2/11 the lca, through the method ecoindicator99, has helped to obtain data about the environmental impact of the structural elements studied (rc and g columns) determining that, of the studied stages, the most critical in both cases was the production stage of the materials, causing more environmental damage. fig. 3 summarizes the results studied for both materials (rc and g). in general, rc columns cause more damage in the three studied indicators. the results are analysed in detail: rc columns produce damage 3.5 times more than g columns to the ecosystem quality (excluding land occupation and exposed independently, because the general trend of the whole was ruled only by it). the rc columns require 32% more resources and affect 53% more the huresults fig. 3 summary of eco-indicators fig. 4 detail of ecosystem quality the calculation through lca manager, is carried out by six stages of calculation: characterization, inventory, indicators, impacts, results and graphs (simpple 2010). the impact categories studied in this research refers to the energy consumption, natural resources and emissions resulting from the processes of each material used and its impact on the environment. these categories are the most representative in the stages studied (extraction, production and construction), also are included in the eco-indicator99, method that was selected due to its wide use and recognition in europe, and included in lca manager 1.3. the eco-indicators 99 selected for the lca, permits to study and report the effects of the investigated processes (rc and g) in the following sections: 1. ecosystem quality (acidification-eutrophication, eco-toxicity and land occupation). 2. natural resources consumption (mineral extraction, and fossil fuels consumption). 3. health (climate change, ozone layer depletion, ionizing radiation, respiratory effects or carcinogenic). eco-indicator 99 is a method of environmental impact assessment, which weights the study to highlight the environmental damage, modeling the resource use and emissions effects on human health, considering the quality of the ecosystems and consumption of natural resources. finally, the impact on these three security parameters are weighted to provide an indicator with a single component (kellenberger and althaus 2009), which allows grouping and comparing. results the lca, through the method ecoindicator99, has helped to obtain data about the environmental impact of the structural elements studied (rc and g columns) determining that, of the studied stages, the most critical in both cases was the production stage of the materials, causing more environmental damage. fig. 3 summarizes the results studied for both materials (rc and g). in general, rc columns cause more damage in the three studied indicators. the results are analysed in detail: rc columns produce damage 3.5 times more than g columns to the ecosystem quality (excluding land occupation and exposed independently, because the general trend of the whole was ruled only by it). the rc columns require 32% more resources and affect 53% more the human health than the g columns. fig. 3. summary of eco-indicators. with regard to the ecosystem quality, the data are separated because in some aspects their understanding is needed (fig. 4). in land occupation indicator the g columns cause damage 108 times higher than rc columns, attributed to excessive deforestation. however, if palliative, preventive and control environmental measures were considered, as moderate logging and, tree planting, this effect is mitigated because the wood is the only building material 100% renewable (barrera 2010) and also reusable. in terms of acidification and eutrophication of the ecosystem, both materials have similar behaviour. however, g columns cause damage 15% higher than rc columns, which is due to the compounds involved to obtain glues of melamine and resorcinol, (used in the gluing the wood layers). the process to get them involves elements such as nitrogen and sulphur, which are potential generators of acidification and eutrophication. in the same way, the rc involves these components in their production, due to reactions generated in the manufacturing of clinker and due to their chemical composition. fig. 4. detail of ecosystem quality continuing the interruption of ecosystem quality, the rc produces 5.4 times more ecotoxicity than the g; the above is attributed to emissions generated by the production of cement clinker, to chemical reactions, and the burning of fossil fuels used (carvalho-filho 2001). with regard to natural resources, it is necessary to indicate that both manufacturing industries (rc and g) are consumers of fossil fuels, for example in the high temperatures for the calcination of clinker or in the glues manufacturing, however this study shows that g generates 15% more damage to consumption of fossil fuels that the rc. concerning the extraction of minerals, rc is the largest consumer, being 22 times more burdensome than g (fig. 5). control environmental measures were considered, as moderate logging and, tree planting, this effect is mitigated because the wood is the only building material 100% renewable (barrera 2010) and also reusable. in terms of acidification and eutrophication of the ecosystem, both materials have similar behaviour. however, g columns cause damage 15% higher than rc columns, which is due to the compounds involved to obtain glues of melamine and resorcinol, (used in the gluing the wood layers). the process to get them involves elements such as nitrogen and sulphur, which are potential generators of acidification and eutrophication. in the same way, the rc involves these components in their production, due to reactions generated in the manufacturing of clinker and due to their chemical composition. fig. 4. detail of ecosystem quality continuing the interruption of ecosystem quality, the rc produces 5.4 times more ecotoxicity than the g; the above is attributed to emissions generated by the production of cement clinker, to chemical reactions, and the burning of fossil fuels used (carvalho-filho 2001). with regard to natural resources, it is necessary to indicate that both manufacturing industries (rc and g) are consumers of fossil fuels, for example in the high temperatures for the calcination of clinker or in the glues manufacturing, however this study shows that g generates 15% more damage to consumption of fossil fuels that the rc. concerning the extraction of minerals, rc is the largest consumer, being 22 times more burdensome than g (fig. 5). man health than the g columns. with regard to the ecosystem quality, the data are separated because in some aspects their understanding is needed (fig. 4). in land occupation indicator the g columns cause damage 108 times higher than rc columns, attributed to excessive deforestation. however, if palliative, preventive and control environmental measures were considered, as moderate logging and, tree planting, this effect is mitigated because the wood is the only building material 100% renewable (barrera 2010) and also reusable. in terms of acidification and eutrophication of the ecosystem, both materials have similar behaviour. however, g columns cause damage 15% higher than rc columns, which is due to the compounds involved to obtain glues of melamine and resorcinol, (used in the gluing the wood layers). the process to get them involves elements such as nitrogen and sulphur, which are potential generators of acidification and eutrophication. in the same way, the rc involves these components in their production, due to reactions generated in the manufacturing of clinker and due to their chemical composition. continuing the interruption of ecosystem quality, the rc produces 5.4 times more ecotoxicity than the g; the above is attributed to emissions generated by the production of cement clinker, to chemical reactions, and the burning of fossil fuels used (carvalho-filho 2001). with regard to natural resources, it is necessary to indicate that both manufacturing industries (rc and g) are consumers of fossil fuels, for example in the high temperatures for the calcination of clinker or fig. 5 consumption of natural resources journal of sustainable architecture and civil engineering 2015/2/11 28 in the glues manufacturing, however this study shows that g generates 15% more damage to consumption of fossil fuels that the rc. concerning the extraction of minerals, rc is the largest consumer, being 22 times more burdensome than g (fig. 5). in addition to its relevant damage in the extraction of mineral resources above mentioned, it is necessary to underline that the rc is the second material most used on the planet (only surpassed by water). the current civilization is based on constructions that utilize it (gaimster and munn 2012), consuming in its production 12.6 billion fig. 6 effects on human health fig. 5. consumption of natural resources in addition to its relevant damage in the extraction of mineral resources above mentioned, it is necessary to underline that the rc is the second material most used on the planet (only surpassed by water). the current civilization is based on constructions that utilize it (gaimster and munn 2012), consuming in its production 12.6 billion tons of raw materials every year, what makes it the biggest consumer of natural resources in the world, and converts in the material with the highest environmental impact when is used with conventional methods (deshpande et al. 2011). analysing the effects on health as a whole, rc columns produce 53% more damage than g columns (fig. 6). the indicator of the respiratory effect is the most critical and is attributed specifically to the emissions of co2, nox and so2 (originated in chemical processes and the burning of fuels) resulting from the production of cement clinker and in the production of steel (carvalho-filho 2001). fig. 6. effects on human health continuing with the effect on human health, both materials have low impact in radiation and ozone layer depletion, in comparison to the rest of the indicators. in terms of climate change, rc columns generate damage 37% higher than g columns (attributed to the emissions of co2, nox and so2), also generate 64% more agents carcinogenic (attributed to small quantities of heavy metals such as cd, cr, hg, pb, which are found by the use of fossil fuels or other types of alternative fuels (carvalho-filho 2001)). conclusions fig. 7 summarizes the effects of the eco-indicators. in this, it can observe that the columns of rc made with a conventional method produce more significant damage than the g columns. due to the nature of each material, the indicator of damage for land occupation is more obvious for g columns; it is also evident, in the extraction of minerals for the production of rc; both with a damage rate close to 100%. fig. 7. summary of ecoindicators99 however, and although both are important consumers of these different raw materials it is noteworthy that g is a 100% renewable (and reusable) material. if an environmental management plan that allows its regeneration is implemented, and if tree felling rules are observed, g is an alternative option to rc, considering an environmentally friendly construction. moreover, although the component materials of the rc are not renewable, they have a high potential for recycling (recycled aggregate to recycled concrete). pretending to build with conventional rc, is unsustainable, as in previous studies have been shown. by contrasts, the use of recycled components (the same concrete incorporated in new cycles as fine or coarse aggregates, wastes from other industries either as aggregates or as supplementary cementitious materials or as additives or additions; among others) in rc is a viable option to consider a sustainable construction. it is important to mention that ecoinvent is not a spanish database. although this study considered european average data and the results are consistent with the literature reviewed, it is evident the need to create local inventories to accurately assess environmental impacts. finally, the lca was verified as feasible to use like environmental assessment tool in the search for construction materials alternatives, in this case used like structural elements, comparing the environmental impacts generated by concrete columns and glulam columns. the lca identified to the laminated wood as an alternative solution in the construction of vertical structural elements such as columns, finding that this could be an option for total replacement of conventional rc. references althaus h.j., kellenberger d., doka g., künniger t. manufacturing and disposal of building materials and inventorying infrastructure in ecoinvent. the international journal of life cycle assessment, 2005; 10(1): 3542. doi:10.1065/lca2004.11.181.4 asif m., muneer t., kelley r. life cycle assessment: a case study of a dwelling home in scotland. building and environment, 2007; 42(3): 1391–1394. doi:10.1016/j.buildenv.2005.11.023 aye l., ngo t., crawford r. h., gammampila r., mendis p. life cycle greenhouse gas emissions and energy analysis of prefabricated reusable building modules. energy and buildings, 2012; 47: 159–168. doi:10.1016/j.enbuild.2011.11.049 barrera j. a. la madera laminada: una alternativa estructural y ambiental [the laminated wood: a structural and environmental alternative]. revista m-m: 10-17. [www.revista-mm.com]. [last access: 11-03-2015] tons of raw materials every year, what makes it the biggest consumer of natural resources in the world, and converts in the material with the highest environmental impact when is used with conventional methods (deshpande et al. 2011). analysing the effects on health as a whole, rc columns produce 53% more damage than g columns (fig. 6). the indicator of the respiratory effect is the most critical and is attributed specifically to the emissions of co 2 , no x and so 2 (originated in chemical processes and the burning of fuels) resulting from the production of cement clinker and in the production of steel (carvalho-filho 2001). continuing with the effect on human health, both materials have low impact in radiation and ozone layer depletion, in comparison to the rest of the indicators. in terms of climate change, rc columns generate damage 37% higher than g columns (attributed to the emissions of co 2 , no x and so 2 ), also generate 64% more agents carcinogenic (attributed to small quantities of heavy metals such as cd, cr, hg, pb, which are found by the use of fossil fuels or other types of alternative fuels (carvalho-filho 2001)). fig. 7 summarizes the effects of the eco-indicators. in this, it can observe that the columns of rc made with a conventional method produce more significant damage than the g columns. due to the nature of each material, the indicator of damage for land occupation is more obvious for conclusions fig. 7 summary of ecoindicators99 29 journal of sustainable architecture and civil engineering 2015/2/11 g columns; it is also evident, in the extraction of minerals for the production of rc; both with a damage rate close to 100%. however, and although both are important consumers of these different raw materials it is noteworthy that g is a 100% renewable (and reusable) material. if an environmental management plan that allows its regeneration is implemented, and if tree felling rules are observed, g is an alternative option to rc, considering an environmentally friendly construction. moreover, although the component materials of the rc are not renewable, they have a high potential for recycling (recycled aggregate to recycled concrete). pretending to build with conventional rc, is unsustainable, as in previous studies have been shown. by contrasts, the use of recycled components (the same concrete incorporated in new cycles as fine or coarse aggregates, wastes from other industries either as aggregates or as supplementary cementitious materials or as additives or additions; among others) in rc is a viable option to consider a sustainable construction. it is important to mention that ecoinvent is not a spanish database. although this study considered european average data and the results are consistent with the literature reviewed, it is evident the need to create local inventories to accurately assess environmental impacts. finally, the lca was verified as feasible to use like environmental assessment tool in the search for construction materials alternatives, in this case used like structural elements, comparing the environmental impacts generated by concrete columns and glulam columns. the lca identified to the laminated wood as an alternative solution in the construction of vertical structural elements such as columns, finding that this could be an option for total replacement of conventional rc. references althaus h.j., kellenberger d., doka g., künniger t. manufacturing and disposal of building materials and inventorying infrastructure in ecoinvent. the international journal of life cycle assessment, 2005; 10(1): 3542. doi:10.1065/lca2004.11.181.4 asif m., muneer t., kelley r. life cycle assessment: a case study of a dwelling home in scotland. building and environment, 2007; 42(3): 1391–1394. doi:10.1016/j.buildenv.2005.11.023 aye l., ngo t., crawford r. h., gammampila r., mendis p. life cycle greenhouse gas emissions and energy analysis of prefabricated reusable building modules. energy and buildings, 2012; 47: 159–168. doi:10.1016/j.enbuild.2011.11.049 barrera j. a. la madera laminada: una alternativa estructural y ambiental [the laminated wood: a structural and environmental alternative]. revista m-m: 10-17. 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[last access: 11-03-2015] bilec m., ries r., matthews h. s., sharrard a. l. example of a hybrid life cycle assessment of construction processes. journal of infrastructure systems, 2006; 12(december): 207–215. doi:10.1061/(asce)1076-0342(2006)12:4(207) cabeza f. l., rincón l., vilariño v., pérez g., castell a. life cycle assessment (lca) and life cycle energy analysis (lcea) of buildings and the building sector: a review. renewable and sustainable energy reviews, 2014; 29: 394-416. de carvalho filho a. c. tesis doctoral: análisis del ciclo de vida de productos derivados del cemento – aportaciones al análisis de los inventarios del ciclo de vida del cemento [phd thesis: analysis of the life cycle of products derived from cementcontributions to the analysis of life cycle inventories of cement]. barcelona, españa: universidad politécnica de cataluña, 2001. deshpande n., kulkarni s. s., patil n. effectiveness of using coarse recycled concrete aggregate in concrete. international journal of earth sciences and engineering, 2011: 4 (6): 913-919. dodoo a., gustavsson l., sathre r. lifecycle primary energy analysis of low-energy timber building systems for multi-storey residential buildings. energy and buildings, 2014; 8: 84-97. ecoinvent centre [www.ecoinvent.org]. 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[last access: 11-032015] gobierno vasco. madera y cambio climático: análisis de ciclo de vida de la madera como material alternativo [wood and climate change: life-cycle assessment of wood as an alternative material]. país vasco: colección lur n. 14, 2009. horvath a., hendrickson c. steel versus steelreinforced concrete bridges: environmental assessment. journal of infrastructure systems, 1998; 4(september): 111–117. doi:10.1061/ (asce)1076-0342(1998)4:3(111) iso 14040. environmental management: life cycle assessment: principles and framework, 2006. kellenberger d., althaus h.j. relevance of simplifications in lca of building components. building and environment, 2009; 44: 818–825. doi:10.1016/j.buildenv.2008.06.002 khasreen m. m., banfill p. f. g., menzies, g. f. lifecycle assessment and the environmental impact of buildings: a review. sustainability, 2009; 1: 674– 701. doi:10.3390/su1030674 o’reilly díaz v. a., bancrofft-hernández r.a., ruizgutiérrez l. las tecnologías del concreto en su ciclo de vida [the technologies of concrete in its life cycle]. cemento y concreto. investigación y desarrollo, 2010; 1(2): 42-47. 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[last access: 11-03-2015]. ortiz o., castells f., sonnemann g. sustainability in the construction industry: a review of recent developments based on lca. construction and building materials, 2009; 23: 28-39. ortiz-rodríguez o., castells f., sonnemann g. life cycle assessment of two dwellings: one in spain, a developed country, and one in colombia, a country under development. science of the total environment, 2010; 408: 2435-2443. perez-garcia j., lippke b., comnick j., manriquez c. an assessment of carbon pools, storage, and wood products market substitution using life-cycle analysis results. wood and fiber science, 2005; 37: 140–148. retrieved from http:// www.scopus.com/inward/record.url?eid=2-s2.032644488738&partnerid=tzotx3y1. peuportier b. l. p. life cycle assessment applied to the comparative evaluation of single family houses in the french context. energy and buildings, 2001; 33: 443–450. doi:10.1016/s0378-7788(00)00101-8 radhi h., sharples s. global warming implications of façade parameters: a life cycle assessment of residential buildings in bahrain. environmental impact assessment review, 2013; 38: 99-108. ramesh t., prakash r., shuklab k.k. life cycle energy analysis of buildings: an overview. energy and buildings, 2010; 42: 1592-1600. rivela b., moreira m. t., muñoz i., rieradevall j., feijoo g. life cycle assessment of wood wastes: a case study of ephemeral architecture. science of the total environment, 2006; 357: 1–11. doi:10.1016/j.scitotenv.2005.04.017 simpple efficient solutions. manual del usuario: lca manager versión 1.3 [user manual: lca manager version 1.3]. tarragona, españa, 2010. utama n. a., mclellan b.c., gheewala s.h., ishihara k.n. embodied impacts of traditional clay versus modern concrete houses. building and environment, 2012; 57: 362-369. venkatarama r. b., jagadish k. embodied energy of common and alternative building materials and technologies. energy and buildings, 2003; 35(2): 129–137. doi:10.1016/s0378-7788(01)00141-4 xiao j., li w., fan y., huang x. an overview of study on recycled aggregate concrete in china (19962011). construction and building materials, 2012; 31: 364-383. xing s., xu z., jun g. inventory analysis of lca on steel and concrete construction office buildings. energy and buildings, 2008; 40: 1188-1193. zabalza-bribián i., aranda-usón a., scarpellini s. life cycle assessment in buildings: state-ofthe-art and simplified lca methodology as a complement for building certification. building and environment, 2009; 44(12): 2510–2520. doi:10.1016/j.buildenv.2009.05.001 zhang z., wua x., yanga x., zhub y. bepas a life cycle building environmental performance assessment model. building and environment, 2006; 41: 669-675. 31 journal of sustainable architecture and civil engineering 2015/2/11 diana carolina gámez-garcía phd student polytechnic university of cataluña, school of architecture of barcelona, department of building architectural main research area lca in construction, recycled concrete address: av. diagonal, 649-651, 08028, barcelona, spain tel. +34 93 4016242 e-mail: diana.carolina.gamez@ estudiant.upc.edu josé manuel gómez-soberón full time professor polytechnic university of cataluña, school of building construction of barcelona, department of building architectural ii main research area concrete recycled, porous structure of concrete, sustainable construction, minimization, reuse and recycling in construction, ict in teaching, virtual campus teachers address doctor marañón, 44-50, 08028, barcelona, spain tel. +34 93 4016242 e-mail: josemanuel.gomez@upc.edu ramón corral-higuera full time professor autonomous university of sinaloa, school of engineering of mochis main research area concrete technology, sustainable concretes characterization techniques applied to pastes, mortars and concretes, and sustainability in construction address fuente de poseidón y ángel flores s/n pte., 81223, los mochis, sinaloa, mexico tel. +52 (668) 812-7641 e-mail: rmn1779@gmail.com jorge luis almaral-sánchez full time professor autonomous university of sinaloa, school of engineering of mochis main research areas concrete technology, sustainable concretes characterization techniques applied to pastes, mortars and concretes, and sustainability in construction address fuente de poseidón y ángel flores s/n pte., 81223, los mochis, sinaloa, mexico tel. +52 (668) 812-7641 e-mail: jalmaral@uas.edu.mx maría consolación gómez-soberón full time professor metropolitan autonomous university. school of civil engineering, department of materials main research area vulnerability of structures and bridges address av. san pablo no. 180. col. reynosa tamaulipas, 02200. delegación azcapotzalco. distrito federal. mexico tel. +34 1 2454520134 e-mail: cgomez@correo.azc.uam.mx luis alberto gómez-soberón professional structural designer alonso y asociados main research area structural design of buildings, seismic performance of buildings address paseo de la palma no. 150-101. colonia lomas de vista hermosa. delegación coajimalpa. méxico, d.f. 05100. mexico tel. +34 1 2454520134 e-mail: laags@hotmail.com about the authors 5 journal of sustainable architecture and civil engineering 2018/2/23 *corresponding author: indre.grazuleviciute@ktu.lt urban acupuncture in historic environment: research of analogues received 2018/07/11 accepted after revision 2018/09/15 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 5-15 doi 10.5755/j01.sace.23.2.21434 urban acupuncture in historic environment: research of analogues jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.21434 aurelija daugėlaitė, indrė gražulevičiūtė-vileniškė* kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania introduction today’s cities face a variety of development, rehabilitation and preservation challenges. historical built environment deserves particular attention in this regard. urban regeneration projects are particularly complex here because of the dense urban fabric and the risk of damage to the heritage values. in order to understand how to overcome these challenges, we explore the concept of urban acupuncture in this research. the urban acupuncture focuses on small, precisely targeted, rapid and usually lowcost changes that positively affect social, ecological, and even economical and physical dimensions of the surrounding environment. the aim of this research was to identify the recent interventions in historic urban environment of kaunas city (lithuania) that can be seen as the analogues of urban acupuncture and to evaluate them using the designed set of criteria integrating the characteristics of urban acupuncture, the patterns of socially and ecologically responsible biophilic design and the requirements for preservation and development of historic built environment. keywords: urban acupuncture, urban intervention, historic urban environment, kaunas. this article deals with the concept of urban acupuncture that has emerged as a part of knowledge transfer trend in urban studies. it involves applying holistic eastern medicine concepts in urban design and management (marciano, 2016) and is based on the precisely localized interventions in the urban fabric in order to regulate so-called “energy flows” (ecological, sociocultural, socioeconomic, and information flows) in the city, so that it can function successfully. the movement and activities of people, the ecological flows, the information flows and exchange can be considered as “energy” in urban acupuncture; meanwhile elements of urban structure, including streets, squares, green areas, buildings etc. can be metaphorically considered as the “organs” of the city (casagrande, 2010; khaerani, 2014; lerner, 2014). as the experience demonstrates, urban acupuncture can be applied locally and systematically (tortosa et al., 2010). the “needles” of urban acupuncture can be various types of interventions and events ranging from the building or park to street festival or any other positive happening in public spaces (lerner, 2014). urban intervention in this this research is considered as the art objects or design solutions in the urban environment, creating a public space or integrated in the existing space and giving it a new expression. most often, the urban interventions are aimed at addressing social, ecological, local identity and similar problems and creating the new quality in the environment. urban acupuncture intervention here is considered as the intervention or the system of interventions in the selected points of urban fabric with social, economic, ecological or other potential in order to activate their “energy” and affect the surrounding territories. journal of sustainable architecture and civil engineering 2018/2/23 6 framework and methods of research urban acupuncture is more efficient in densely built and densely populated urban fabric (walker, 2015), usually characteristic to historic urban environment. this research is concentrated on the interventions having the character of urban acupuncture in historic urban environment; historic urban environment, according to vienna memorandum (2005), here „refers to ensembles of any group of buildings, structures and open spaces, in their natural and ecological context, including archaeological and palaeontological sites, constituting human settlements in an urban environment over a relevant period of time, the cohesion and value of which are recognized from the archaeological, architectural, prehistoric, historic, scientific, aesthetic, socio-cultural or ecological point of view.“ based on the potential benefits of urban acupuncture in historic urban environment, seven hypothetical statements of the research were formulated: 1. urban acupuncture interventions in historic urban environment can be beneficial for the actualization of heritage, for highlighting of its’ valuable features, and attracting attention of the society. 2. applying the principles of urban acupuncture allows developing, improving or adding new features to the system of public spaces of a historical part of the city. 3. successful urban interventions correspond to the basic principles of biophilic design (browning et al., 2014) and urban acupuncture (lerner, 2014). 4. the architectural-urban context determines the type of urban acupuncture interventions. 5. interventions of urban acupuncture can influence the ecological system, can restore or create biodiversity, ecological balance and the links between humans and nature. 6. urban acupuncture interventions in the historic environment can create or re-create social viability. 7. urban acupuncture interventions can positively affect the urban landscape. the aim of the research is to identify the recent interventions (in a timeframe of 5 years) in the historic urban fabric of the second largest lithuanian city kaunas that can be seen as the analogues of urban acupuncture and to evaluate them using the designed set of criteria in order to test the above-presented hypothetical statements. the methods of research include the analysis of literature, the classification of urban acupuncture interventions and the design of the set of criteria for their evaluation, the identification of interventions, that can be seen as the analogues of urban acupuncture in kaunas historic urban fabric and their evaluation using the designed set of criteria, generalization and formulation of conclusions. the research was aimed at finding and evaluating the analogues of urban acupuncture in the historic environment of kaunas; thus the classification of urban acupuncture interventions and a set of criteria for their evaluation were necessary. after the analysis of examples and literature (lerner, 2014; network…, 2018), it was noticed that some interventions have a temporal impact and the impact in a very limited space, some interventions have a wider (for example, district level) impact, there can be individual and systematic interventions (tortosa et al., 2010). consequently, four types of possible urban acupuncture interventions were distinguished in this research: _ non-physical intervention (does not have a permanent physical form, but has a significant impact on the viability of the site, for example, the iconic music piece, tradition, street artists); _ intervention of local impact (affecting only the surrounding environment, for example, the square, where it is located); _ intervention of wide impact (localized in one place, although affecting the viability of a wider area, for example, the district); _ systemic intervention (forms a certain network of spaces in order to influence the whole city). the urban acupuncture concept integrates social, ecological and spatial aspects, thus the system of criteria for evaluation of urban acupuncture interventions should encompass these dimensions as 7 journal of sustainable architecture and civil engineering 2018/2/23 well. the previous experience of assessment of public spaces was applied; the set of criteria for the assessment of urban acupuncture interventions was created integrating the public space assessment questionnaires from the project for public spaces (project..., 2018), characteristics of urban acupuncture (casagrande, 2010; khaerani, 2014; lerner, 2014), the 14 the patterns of socially and ecologically responsible biophilic design formulated by terrapin bright green (browning et al., 2014), the principles of sustainability and the requirements for preservation of historic built environment. the possibility to give scores to some of the indicators and to calculate an overall assessment in order to compare the interventions was envisioned as well. the set of criteria was structured into five sections: 1. general data. general data includes the description of the intervention: its’ location, the date of implementation, the area in sq. m, the period of implementation, envisioned time of existence, functions, the cost in euros, financing source, author(s) and the client (initiator(s)) of the project. 2. assessment of social and psychological aspects. this section integrates the characteristics and the questions for their evaluation targeted at sociability, activities, and functions with reference to the project for public spaces. the project for public spaces is a non-profit organization that analyses more and less socially successful public spaces and had distinguished a system of criteria for their assessment. the system includes such sets of characteristics as access and linkages, comfort and image, uses and activities, and sociability and presents the array of observation and public space assessment questions, part of which is integrated in this research (table 1). table 1 criteria for evaluation of social and psychological aspects of the interventions (project..., 2018) “energy” in the space of the intervention – community aspect, sociability evaluation scores: yes – 5; partially – 2.5; no – 0 development of new attraction point do people usually stay longer in the space and do something in it? do people use this space for meetings? do the groups of people come together in the space? do they interact with each other? do people choose this space intentionally? community ties do people in this area feel belonging to the community? do people know their neighbors most often? do people smile? do people support eye contact with each other? people’s attachment to the territory are people collecting litter? do people invite their friends or relatives to visit this space? activities, functions and participation dominant functions what is the official function of the space? how many different types of activities can be found in the space? evaluation scores: 1 function – 1; 2 functions – 2 etc. 5 functions or more – 5 what are the missing functions? which parts of the space are used and which are not? evaluation scores: almost unused – 0; the area of the main pedestrian flows – 1.5; the most of the territory is used – 2.5; the entire territory is used – 5 diversity of users what is the balance between men and women in the space? evaluation scores: balanced – 5; only one group prevails – 2.5 what age groups use the space? evaluation scores: diverse – 5; 1-2 groups – 2.5; only 1 specific group – 1 how is the space used during the day? evaluation scores: round the clock – 5; during the day and in the evening 2.5; only in one specific time during the day – 1 is it possible to use the space in cold season? evaluation scores: yes – 5; partially – 2.5; no – 0 journal of sustainable architecture and civil engineering 2018/2/23 8 3. assessment of urban-architectural aspects. the criteria for the assessment of the urban quality of the interventions integrate some of the criteria developed by project for public spaces (project..., 2018) and the criteria for the assessment of the contextuality and image of the intervention (table 2). table 2 criteria for evaluation urbanarchitectural aspects of the interventions (project..., 2018) links with the context evaluation scores: yes – 5; partially – 2.5; no – 0 significance in the cityscape has the intervention changed the image of the area? does the intervention affect the city’s panoramas, visual axes, etc.? significance to the spatial quality of the city does the intervention complement, improve, or shape the public space system in the city? does the intervention reveal the valuable features of heritage and other valuable objects, actualize them and attract public attention? does the intervention create new links, for example, between city and nature, humans and the city? does the intervention create visual links with other urban spaces? is the intervention a landmark? is the intervention one of the accents of the city? links with natural environment does the intervention create visual links with natural elements? does the intervention create physical connections with natural elements? accessibility evaluation scores: yes – 5; partially – 2.5; no – 0 visual accessibility is the space visible from the distance? can the space be recognized from the distance? physical accessibility can people easily get into the space? do the sidewalks lead to the space from adjacent territories? is the space adapted to the people with special needs? are the paths in the space leading people where they really want to go? accessibility by transport is it possible to reach the space in public transport? is it possible to reach the space by bicycle? comfort and image safety evaluation scores: yes – 5; partially – 2.5; no – 0 is the first impression about the space positive? does the space create the feeling of safety? comfort evaluation scores: yes – 5; partially – 2.5; no – 0 are there enough sitting places? are the sitting places comfortably located? is there a possibility to choose where to sit: in the sun or in the shade? is the space designed for people (is it not occupied by cars)? image is the space clean, not littered? evaluation scores: yes – 5; partially – 2.5; no – 0 who is responsible for the maintenance of the space? are people taking photos in the space? evaluation scores: yes – 5; some – 2.5; no – 0 how many photo opportunities are there? evaluation scores: a lot of – 5; several (3 or 4) – 2.5; just 1 or 2 1 has the intervention been created by professionals or community? evaluation scores: involvement of community representatives + 5 points what is the stylistic character of the intervention (natural, ecological, urban, street art, etc.)? what materials are predominant? 9 journal of sustainable architecture and civil engineering 2018/2/23 table 3. criteria for evaluation of ecological aspects of the interventions (browning et al., 2014; biophilic, 2017) natural character of space valuable features evaluation scores: yes – 5; partially – 2.5; no – 0 has the intervention preserved, highlighted the existing landscape values (terrain, water bodies, greenery, etc.)? has the intervention provided additional natural features to the environment? built-up areas and other impermeable surfaces ratio, percent green areas 20 percent of green area – 1; 90 percent of green area – 5 ratio, percent quality of green areas: types according to the diversity of plants evaluation scores: none – 0; lawn – 2; meadow – 3; scrubs – 4; trees and scrubs – 5 lawn / meadow / scrubs / trees and scrubs pollution evaluation scores: yes – 5; partially – 2.5; no – 0 has the intervention reduced pollution of the environment? installation resources evaluation scores: yes – 5; partially – 2.5; no – 0 are the sustainable (recycled or locally available) materials used for the intervention? patterns of biophilic design evaluation scores: very good – 5; good – 4; average – 3; poor – 2; very bad 1 nature in the space direct contact with nature or natural systems visual links with nature views to elements of nature, living systems and natural processes. non-visual links with nature design features that stimulate other senses of sound, touch, smell, and taste reminding about connection with nature. non-rhythmic sensory stimuli well known and at the same time unpredictable sensory stimuli of nature, such as the gentle sway of grasses or leaves in a breeze, or ripples on water. thermal and airflow variability the subtle changes in air and surface temperature, humidity and airflow characteristic to natural environments. presence of water possibility to see, hear or touch water. dynamic and diffuse light the use of light and shadow to mimic the lighting conditions or circadian processes occurring in nature. links with natural systems an awareness or proximity to natural processes, such as seasonal changes. natural analogues representations and abstractions of nature biomorphic forms and patterns symbolic representations within the design of the patterns, shapes, textures or arrangements found in nature. material connections with nature using in design the natural materials, grains, textures and elements etc. that distinctly reflect the environment to create a comprehensive sense of the natural world. complexity and order spatial hierarchies similar to natural ones. nature of the space spatial conditions derived from nature prospect possibility to see beyond the immediate surroundings or over long distances. refuge possibility to look over the surroundings from the safety of a protected position away from the central areas of activity. mystery replication of the excitement and unknown elements of the great outdoors in the built environment. the promise of more information, achieved through partially obstructed long-distance views, design revelations, surprising installations or unexpected architectural features drawing in and engaging with the environment. risk / peril the thrill of danger from an identifiable risk, coupled with the sense of a reliable safeguard. journal of sustainable architecture and civil engineering 2018/2/23 10 4. assessment of ecological aspects. the assessment of ecological aspects of the interventions is based on the 14 patterns of biophilic design. the 14 patterns were developed by environmental consulting and strategic planning company terrapin bright green, which is committed to improving the human environment through high-performance development, policy, and related research. these patterns are grouped into three categories: nature in the space patterns (visual connection with nature, non-visual connection with nature, non-rhythmic sensory stimuli, thermal and airflow variability, presence of water, dynamic and diffuse light, connection with natural systems), natural analogues patterns (biomorphic forms and patterns, material connection with nature, complexity and order), nature of the space patterns (prospect, refuge, mystery, risk/ peril) (browning et al., 2014; biophilic, 2017) three categories of patterns and additional features related with the ratio of greenery in the area, pollution, ant the use of sustainable materials in the implementation of the project are included into the assessment of ecological aspects (table 3). 5. assessment according to the principles of urban acupuncture. the assessment of the intervention according to the principles of urban acupuncture includes such criteria as bringing new life and people to the urban area, highlighting the potential of the place, being stimulus to community life, identity re-creation or development, development of missing features of the urban fabric, stimulation of diversity of activities (casagrande, 2010; khaerani, 2014; lerner, 2014). each of these criteria can be evaluated in scores: 1 – positive assessment; 2 – partial correspondence to the criterion; 0 – the intervention does not correspond to the criterion. table 4 types of urban interventions found in historical part of kaunas city no. intervention functions life-time non-physical intervention 1. cabbage field, šančiai cultural, social events since 2014 intervention of local impact 1. educational garden in kaunas botanical garden of vytautas magnus university education, community garden june – november, 2017 2. garden in iii mansion’s courtyard (k. donelaičio g. 52) of vytautas magnus university community‘s garden summer, 2013 3. street art of kaunas: vytenis jakas “unicorn”, 2018 m. ; tadas vincaitis-plūgas – fresco “the yard”, vilijampolė, 2017; tadas šimkus – underground passage at savanoriu prospect and žemaičių street crossing, 2014; linas kazulionis “contemporary ladies”, 2015 and other. aesthetic, creating meaningfulness of abandoned places constantly 4. square of j. mačiūnas symbolic since 2017 5. the monument for routine symbolic – aspiration to draw attention to the problems of aesthetic, vitality and progress of the city since 2014 6. street art zone creative since 2015 intervention of wide impact 1. former factory of shoes “lituanica” – former ministry of “fluxus” cultural, events 2012-2013 2. courtyard gallery cultural, community since 2016 3. castle’s ampitheather sitting, events since 2017 4. cafe „culture“ of kaunas picture gallery, street art project „kekto“ food service, events cafe since 2015, „kekto“ – 2017 systemic intervention not found the analogues of the types of urban acupuncture interventions were identified in the territory of kaunas (table 4), except the systemic intervention. results and discussion 11 journal of sustainable architecture and civil engineering 2018/2/23 three interventions (cabbage field area in a historic district šančiai and street art zone and courtyard gallery initiative in kaunas new town) were selected for further detailed analysis and evaluation. the criteria for selection of these interventions were the following: the intervention must be implemented in the historic urban fabric, the intervention must provide the space accessible for pedestrians, the intervention should generate public space and gather community, and this must be still existing intervention. each of three interventions was evaluated according to the prepared set of criteria in an expert evaluation by the authors of the research. the interventions received score for each point, which had the possibility of evaluation in scores, after that these were calculated into total score. after this the total score was multiplied by 5 and divided by the maximum possible evaluation in scores for each section. the multiplying by 5 was necessary to receive the final evaluation score in the five scores scale. table 5 and table 6 demonstrates the evaluation in scores of social and psychological aspects and the correspondence to urban acupuncture features of selected interventions. in the table 7 the summary of evaluation is presented. cabbage field šančiai street art zone courtyard gallery “energy” in the space of the intervention – community aspect, sociability development of new attraction point do people usually stay longer in the space and do something in it? 2.5 0 5 do people use this space for meetings? 0 0 0 do the groups of people come together in the space? do they interact with each other? 2.5 0 0 do people choose this space intentionally? 5 5 5 community ties do people in this area feel belonging to the community? 5 0 2.5 do people know their neighbors most often? 5 0 5 do people smile? 5 0 5 do people support eye contact with each other? 5 0 5 people’s attachment to the territory are people collecting litter? 5 0 5 do people invite their friends or relatives to visit this space? 5 0 5 activities, functions and participation dominant functions how many different types of activities can be found in the space? 1 2 2 which parts of the space are used and which are not? 5 1.5 5 diversity of users what is the balance between men and women in the space? 5 5 5 what age groups use the space? 5 2.5 2.5 how is the space used during the day? 2.5 1 2.5 is it possible to use the space in cold season? 5 5 5 total scores 63,50 (of 80) 22,0 (of 80) 59,5 (of 80) evaluation of social and psychological aspects in scores 5* total sores / 80 3,97 1,37 3,72 table 5 the evaluation in scores of social and psychological aspects of selected interventions in kaunas journal of sustainable architecture and civil engineering 2018/2/23 12 cabbage field was the best-evaluated site according to the criteria. this place acts as attraction point during events only, however it is the place where strong bonds of the community can be perceived. it plays a role of the meeting place of the community and has a wide variety of functions and attracts the diversity of people during events, however at other times it is totally abandoned. this place supplements the system of public spaces of the area and is probably the largest and the only one space for public events in šančiai historic district. however, sense of safety, comfort and the image of the place are very poor. even if the cabbage field is characterised by the largest ratio of green space, its quality as a green public space is low. however, it was the place, which satisfied the principles of urban acupuncture the best – it has brought new energy to the liveliness of the area, strengthened bonds of the community and encouraged the development of local identity. table 6 the evaluation in scores of elected interventions in kaunas according the principles of urban acupuncture cabbage field šančiai street art zone courtyard gallery brought new life to the space 5 2,5 5 highlighted the potential of the place 5 2,5 5 became a stimulus to community life 5 2,5 5 preserved or re-created local identity 5 2,5 5 developed missing features of the urban fabric 5 5 0 stimulates the diversity of activities 0 0 0 attracts people to the space 5 5 5 total scores 30 (of 35) 20 (of 35) 25 (of 35) evaluation of social and psychological aspects in scores 5* total sores / 35 4.29 2.86 3.57 table 7 summary table of evaluation of selected interventions evaluation criteria non-physical intervention in place created by community intervention of local impact intervention of wide impact cabbage field šančiai street art zone courtyard gallery evaluation of social and psychological aspects 3,97 1,37 3,72 evaluation urban-architectural aspects 2,73 1,96 3,75 evaluation of ecological aspects 3,65 1,50 3,18 assessment according to the principles of urban acupuncture 4,29 2,86 3,57 total score 3,66 (good) 1,92 (poor) 3,56 (good) fig. 1 cabbage field in šančiai (authors’ pictures) evaluation of social and psychological aspects in scores 5* total sores / 35 4.29 2.86 3.57 table 7. summary table of evaluation of selected interventions. evaluation criteria non-physical intervention in place created by community intervention of local impact intervention of wide impact cabbage field šančiai street art zone courtyard gallery evaluation of social and psychological aspects 3,97 1,37 3,72 evaluation urban-architectural aspects 2,73 1,96 3,75 evaluation of ecological aspects 3,65 1,50 3,18 assessment according to the principles of urban acupuncture 4,29 2,86 3,57 total score 3,66 (good) 1,92 (poor) 3,56 (good) cabbage field was the best-evaluated site according to the criteria. this place acts as attraction point during events only, however it is the place where strong bonds of the community can be perceived. it plays a role of the meeting place of the community and has a wide variety of functions and attracts the diversity of people during events, however at other times it is totally abandoned. this place supplements the system of public spaces of the area and is probably the largest and the only one space for public events in šančiai historic district. however, sense of safety, comfort and the image of the place are very poor. even if the cabbage field is characterised by the largest ratio of green space, its quality as a green public space is low. however, it was the place, which satisfied the principles of urban acupuncture the best – it has brought new energy to the liveliness of the area, strengthened bonds of the community and encouraged the development of local identity. fig. 1. cabbage field in šančiai (authors’ pictures) courtyard gallery took the second place of evaluation according to the criteria. this place has formed a very strong and active attraction point, having visual connections with other spaces. strong relations between community members are apparent here. the residents seem to be connected to the place as well. as a cabbage field, it also enriched kaunas as one more public space. the space is felt as safe and visually appealing. people here are taking a lot of photographs. even though it has very few natural features (which is quite complicated in such urbanised area), it gained quite good score in ecological evaluation because it had a lot of biophilic features, such as spatial hierarchy, prospect, refuge, mystery, peril, etc. according to urban acupuncture features, the place received good evaluation because it matched most of the principles. evaluation of social and psychological aspects in scores 5* total sores / 35 4.29 2.86 3.57 table 7. summary table of evaluation of selected interventions. evaluation criteria non-physical intervention in place created by community intervention of local impact intervention of wide impact cabbage field šančiai street art zone courtyard gallery evaluation of social and psychological aspects 3,97 1,37 3,72 evaluation urban-architectural aspects 2,73 1,96 3,75 evaluation of ecological aspects 3,65 1,50 3,18 assessment according to the principles of urban acupuncture 4,29 2,86 3,57 total score 3,66 (good) 1,92 (poor) 3,56 (good) cabbage field was the best-evaluated site according to the criteria. this place acts as attraction point during events only, however it is the place where strong bonds of the community can be perceived. it plays a role of the meeting place of the community and has a wide variety of functions and attracts the diversity of people during events, however at other times it is totally abandoned. this place supplements the system of public spaces of the area and is probably the largest and the only one space for public events in šančiai historic district. however, sense of safety, comfort and the image of the place are very poor. even if the cabbage field is characterised by the largest ratio of green space, its quality as a green public space is low. however, it was the place, which satisfied the principles of urban acupuncture the best – it has brought new energy to the liveliness of the area, strengthened bonds of the community and encouraged the development of local identity. fig. 1. cabbage field in šančiai (authors’ pictures) courtyard gallery took the second place of evaluation according to the criteria. this place has formed a very strong and active attraction point, having visual connections with other spaces. strong relations between community members are apparent here. the residents seem to be connected to the place as well. as a cabbage field, it also enriched kaunas as one more public space. the space is felt as safe and visually appealing. people here are taking a lot of photographs. even though it has very few natural features (which is quite complicated in such urbanised area), it gained quite good score in ecological evaluation because it had a lot of biophilic features, such as spatial hierarchy, prospect, refuge, mystery, peril, etc. according to urban acupuncture features, the place received good evaluation because it matched most of the principles. 13 journal of sustainable architecture and civil engineering 2018/2/23 courtyard gallery took the second place of evaluation according to the criteria. this place has formed a very strong and active attraction point, having visual connections with other spaces. strong relations between community members are apparent here. the residents seem to be connected to the place as well. as a cabbage field, it also enriched kaunas as one more public space. the space is felt as safe and visually appealing. people here are taking a lot of photographs. even though it has very few natural features (which is quite complicated in such urbanised area), it gained quite good score in ecological evaluation because it had a lot of biophilic features, such as spatial hierarchy, prospect, refuge, mystery, peril, etc. according to urban acupuncture features, the place received good evaluation because it matched most of the principles. fig. 2 courtyard gallery (authors’ pictures) fig. 2. courtyard gallery (authors’ pictures) street art zone received the poor evaluation according to the criteria. the place did not form active attraction point. it functions more as a passageway rather than a public space. it is not lively at all, which might be influenced by its remote location, lack of visual connections. developing the site, the opportunity was not taken to make use of the river nearby – the site has no other connections with it except that it runs nearby. the sense of safety is poor and the image is more like abandoned space (even if it is clean) rather than space for creativity. according to urban acupuncture principles, it supposed to act as acupunctural point, however bonds of the community did not emerge in this place and the place might be too much remote to be lively; however, as unexpected feature of environment it is very welcomed. fig. 3. street art zone (authors’ pictures) evaluation of hypothetical statements 1. the research showed that urban acupuncture interventions were beneficial for historic environment because they supplemented its value by new features: new public spaces emerged, attention of the society was attracted to neglected spaces, liveliness was brought to some heritage sites. 2. urban acupuncture interventions added a lot of new features and improved the system of public spaces in kaunas historical part. fig. 2. courtyard gallery (authors’ pictures) street art zone received the poor evaluation according to the criteria. the place did not form active attraction point. it functions more as a passageway rather than a public space. it is not lively at all, which might be influenced by its remote location, lack of visual connections. developing the site, the opportunity was not taken to make use of the river nearby – the site has no other connections with it except that it runs nearby. the sense of safety is poor and the image is more like abandoned space (even if it is clean) rather than space for creativity. according to urban acupuncture principles, it supposed to act as acupunctural point, however bonds of the community did not emerge in this place and the place might be too much remote to be lively; however, as unexpected feature of environment it is very welcomed. fig. 3. street art zone (authors’ pictures) evaluation of hypothetical statements 1. the research showed that urban acupuncture interventions were beneficial for historic environment because they supplemented its value by new features: new public spaces emerged, attention of the society was attracted to neglected spaces, liveliness was brought to some heritage sites. 2. urban acupuncture interventions added a lot of new features and improved the system of public spaces in kaunas historical part. fig. 2. courtyard gallery (authors’ pictures) street art zone received the poor evaluation according to the criteria. the place did not form active attraction point. it functions more as a passageway rather than a public space. it is not lively at all, which might be influenced by its remote location, lack of visual connections. developing the site, the opportunity was not taken to make use of the river nearby – the site has no other connections with it except that it runs nearby. the sense of safety is poor and the image is more like abandoned space (even if it is clean) rather than space for creativity. according to urban acupuncture principles, it supposed to act as acupunctural point, however bonds of the community did not emerge in this place and the place might be too much remote to be lively; however, as unexpected feature of environment it is very welcomed. fig. 3. street art zone (authors’ pictures) evaluation of hypothetical statements 1. the research showed that urban acupuncture interventions were beneficial for historic environment because they supplemented its value by new features: new public spaces emerged, attention of the society was attracted to neglected spaces, liveliness was brought to some heritage sites. 2. urban acupuncture interventions added a lot of new features and improved the system of public spaces in kaunas historical part. street art zone received the poor evaluation according to the criteria. the place did not form active attraction point. it functions more as a passageway rather than a public space. it is not lively at all, which might be influenced by its remote location, lack of visual connections. developing the site, the opportunity was not taken to make use of the river nearby – the site has no other connections with it except that it runs nearby. the sense of safety is poor and the image is more like abandoned space (even if it is clean) rather than space for creativity. according to urban acupuncture principles, it supposed to act as acupunctural point, however bonds of the community did not emerge in this place and the place might be too much remote to be lively; however, as unexpected feature of environment it is very welcomed. fig. 2. courtyard gallery (authors’ pictures) street art zone received the poor evaluation according to the criteria. the place did not form active attraction point. it functions more as a passageway rather than a public space. it is not lively at all, which might be influenced by its remote location, lack of visual connections. developing the site, the opportunity was not taken to make use of the river nearby – the site has no other connections with it except that it runs nearby. the sense of safety is poor and the image is more like abandoned space (even if it is clean) rather than space for creativity. according to urban acupuncture principles, it supposed to act as acupunctural point, however bonds of the community did not emerge in this place and the place might be too much remote to be lively; however, as unexpected feature of environment it is very welcomed. fig. 3. street art zone (authors’ pictures) evaluation of hypothetical statements 1. the research showed that urban acupuncture interventions were beneficial for historic environment because they supplemented its value by new features: new public spaces emerged, attention of the society was attracted to neglected spaces, liveliness was brought to some heritage sites. 2. urban acupuncture interventions added a lot of new features and improved the system of public spaces in kaunas historical part. fig. 2. courtyard gallery (authors’ pictures) street art zone received the poor evaluation according to the criteria. the place did not form active attraction point. it functions more as a passageway rather than a public space. it is not lively at all, which might be influenced by its remote location, lack of visual connections. developing the site, the opportunity was not taken to make use of the river nearby – the site has no other connections with it except that it runs nearby. the sense of safety is poor and the image is more like abandoned space (even if it is clean) rather than space for creativity. according to urban acupuncture principles, it supposed to act as acupunctural point, however bonds of the community did not emerge in this place and the place might be too much remote to be lively; however, as unexpected feature of environment it is very welcomed. fig. 3. street art zone (authors’ pictures) evaluation of hypothetical statements 1. the research showed that urban acupuncture interventions were beneficial for historic environment because they supplemented its value by new features: new public spaces emerged, attention of the society was attracted to neglected spaces, liveliness was brought to some heritage sites. 2. urban acupuncture interventions added a lot of new features and improved the system of public spaces in kaunas historical part. fig. 3 street art zone (authors’ pictures) journal of sustainable architecture and civil engineering 2018/2/23 14 evaluation of hypothetical statements 1. the research showed that urban acupuncture interventions were beneficial for historic environment because they supplemented its value by new features: new public spaces emerged, attention of the society was attracted to neglected spaces, liveliness was brought to some heritage sites. 2. urban acupuncture interventions added a lot of new features and improved the system of public spaces in kaunas historical part. 3. the analysed interventions corresponded to the most of biophilic design and urban acupuncture features. 4. the research did not show that architectural-urban context would determine the type of urban acupuncture intervention – it was very diverse. 5. it was not possible to evaluate in this research if urban acupuncture interventions can influence the ecological system, restore or create biodiversity, ecological balance or the links between humans and nature because there was no such ecology-based intervention in kaunas. 6. it was found that urban acupuncture interventions can definitely create or re-create social viability in the urban space. 7. urban acupuncture interventions definitely positively affect urban landscape and bring new values to it. 1 the concept of urban acupuncture is based on the precisely localized interventions in the ur-ban fabric in order to regulate the ecological, sociocultural, socioeconomic, and information flows in the city, so that it can function successfully. the research had identified numerous recent interventions in the urban fabric of kaunas, that can be seen as the analogues of urban acupuncture. three interventions cabbage field area in a historic district šančiai and street art zone and courtyard gallery initiative in kaunas new town – were selected for further evaluation. 2 the system of criteria designed for the assessment of urban acupuncture analogues in-cludes sections: general description, assessment of social and psychological aspects, assessment of urban-architectural aspects, assessment of ecological aspects, assessment according to the principles of urban acupuncture. 3 the assessment has demonstrated that the majority of recently implemented interven-tions are of artistic or street art character and usually do not create a usable public space. 4 the selected space-creating interventions had successfully enlivened and added some values to the system of public spaces in kaunas, and helped to direct the attention to abandoned and derelict urban areas. the wide impact intervention courtyard gallery attracted visitors from different parts of the city. the analysed cases had revealed the mutual links between communities and interventions: the cabbage field was initiated by the community; meanwhile the initiator of the courtyard galley has realized his ideas first and then the neighborhood community has emerged. 5 however, it can be concluded that analysed interventions lack components that create so-cial and ecological processes. even if these spaces are viewed positively by the society, their potential is not fully employed. 6 no systemic urban acupuncture interventions and interventions making significant impact on city-scape were found in kaunas currently. the ecologically influential interventions were lacking as well. conclusions references browning w., ryan c., clancy j. 2014. 14 patterns of biophilic design. improving health & well-being in the built environment 2014 (accessed 14 april 2018). available at: https://www.terrapinbrightgreen.com/wp-content/uploads/2014/09/14-patterns-of-biophilic-design-terrapin-2014p.pdf biophilic design. an introduction to 14 patterns 2017 (accessed 14 april 2018). available at: http:// 15 journal of sustainable architecture and civil engineering 2018/2/23 www.interface.com/eu/en-gb/campaign/biophilic-design/14-patterns-of-biophilic-design-en_gb casagrande m. 2010. urban acupuncture (accessed 14 april 2018). available at: http://thirdgenerationcity.pbworks.com/f/urban%20acupuncture.pdf khaerani, adenan. introduction to urban acupuncture: towards a better bandung city. what’s the story? 2014 (accessed 25 october 2017). available at: https:// khaeraniadenan.wordpress.com/2014/01/12/introduction-to-urban-acupuncture-towards-a-better-bandung-city/comment-page-1/ lerner j. urban acupuncture. celebrating pinpricks of change that enrich city life. london: island press; 2014. marciano t. a. 2016. applying eastern medicine concepts in urban design for mental health (accessed 18 june 2018). available at: https://www. urbandesignmentalhealth.com/blog/category/urban-planning network of urban acupuncture (accessed 18 june 2018). available at: http://www.urbanacupuncture. network/ tortosa l., vicent j. f., zamora a., oliver j. l. 2010. a neural network model to develop urban acupuncture. lecture notes in computer science, 2010; 6276: 31-40. https://doi.org/10.1007/978-3-64215387-7_7 vienna memorandum world heritage and contemporary architecture – managing the historic urban landscape 2005 (accessed 18 june 2018). available at: http://unesco.lt/uploads/file/failai_veikla/kultura/ra_vienna_memorandum.pdf walker j. biophilic urban acupuncture: the importance of biophilia in urban places 2015 (accessed 18 march 2018). available at: https://www.terrapinbrightgreen.com/blog/2015/10/biophilic-urban-acupuncture-biophilia-in-urban-places/ aurelija daugėlaitė master student kaunas university of technology, faculty of civil engineering and architecture main research areas sustainable urbanism, urban acupuncture address kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. e-mail: aurelijai@gmail.com about the authors indrė gražulevičiūtė-vileniškė assoc. professor kaunas university of technology, faculty of civil engineering and architecture main research areas valuation and preservation of cultural heritage, management of rural-urban interface, sustainable architecture address kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. tel.: +370 37 451546 e-mail: indre.grazuleviciute@ktu.lt https://doi.org/10.1007/978-3-642-15387-7_7 https://doi.org/10.1007/978-3-642-15387-7_7 79 journal of sustainable architecture and civil engineering 2015/2/11 jsace 2/11 journal of sustainable architecture and civil engineering vol. 2 / no. 11 / 2015 pp. 79-87 doi 10.5755/j01.sace.11.2.12660 © kaunas university of technology received 2015/03/02 accepted after revision 2015/06/01 influence of the concrete mixture compaction time on density and compressive strength of hardened concrete samples influence of the concrete mixture compaction time on density and compressive strength of hardened concrete samples ramūnas pocius jsc “peikko lietuva”, naglio str. 4a, lt-52367 kaunas, lithuania kaunas university of technology, faculty of civil engineering and architecture studentu str. 48, lt-51367 kaunas, lithuania mindaugas daukšys, lukas venčkauskas, mindaugas augonis, šarūnas kelpša kaunas university of technology, faculty of civil engineering and architecture studentu str. 48, lt-51367 kaunas, lithuania paper discusses the influence of the concrete mixture compaction time on density and compressive strength of hardened concrete samples. concrete specimens, of diameter about 106 mm (d) and height about 1000 mm (h), were formed during the experiment. the ratio of height and diameter h/d was 9.4. concrete mixture, placed in forms, was compacted by poker vibrator, when vibrating element was placed to the top part of the form. different time was used for compacting mixture in forms: 0, 3, 6, 9 and 12 s. the study results show the changes in density and compressive strength of samples (radius about 106 mm and height about 100 mm) depending on the location of the sample in specimen (1000 mm height). it was found, that samples taken from different height of the specimen had different density and compressive strength. keywords: compaction time, compressive strength, concrete mixture, density, hardened concrete. *corresponding author: mindaugas.dauksys@ktu.lt http://dx.doi.org/10.5755/j01.sace.11.2.12660 density is defined as the measure of how much particles of an element or material is squeezed into a given space. the more closely packed the particles, the higher the density of the material. higher levels therefore, indicate a corresponding degree of compaction. from compaction degree depended density, compressive strength, water permeability, durability and other properties of hardened concrete. depending on the physical state, concrete mixture is in intermediate place between solids and viscous fluids. during the quiescence phase, fresh concrete is like solid body, and at the phase then it’s mixed, pumped or vibrated – it looks like viscous fluid. liquefaction of concrete mixture due to mechanical effects and thickening of the mixture after stopping them is called thixotropy. (gurskis 2008). rheological characteristics of the concrete mixtures depend on mechanical impact. thixotintroduction journal of sustainable architecture and civil engineering 2015/2/11 80 ropy usually becomes apparent during vibration when shear stress and viscosity go down (khayat et al. 2002, roussel 2006, mewis and wagner 2009). because concrete itself is a porous composite material, the pores in concrete structure are classified as compaction pores, air pores and capillary pores (which affect durability) and gel pores. the change in the compaction pores may significantly affect the carbonation rate and the sorptivity coefficient, and compacting of the fresh concrete is the more important in terms of the durability (gonen and yazicioglu 2007). to assess adequate level of vibration, consideration should be given to match the amplitude of vibration and concrete viscosity. high amplitude means greater vibratory forces. the viscosity of the mix should be strong enough to bear these forces while keeping the suspensions of coarse aggregates. thus, the amplitude of vibration should match the viscosity of mix when applying vibration (safawi et al. 2005). according to authors (arslan et al. 2005) in normal construction practice, concrete is placed in 1 m layer and compacted by using poker type vibrators, which are immersed into only the top 1 m of the concrete. if concrete is placed to a depth of 1 m, the vibrator is immersed 1 m into the concrete. the concrete is completely fluidised and the lateral pressure is hydrostatic. if concrete is placed to a depth of 2 m, the effect of the vibrator will extend below the vibrator and the 2 m depth of concrete will be fluidised, giving hydrostatic pressure. if concrete is placed to a depth of 3 m, the lower concretes develop significant shear strength, settling vertically under load and developing friction between the concrete and the formwork surface. according to authors (banfill et al. 2011) in the inner liquefied zone around the vibrator the flow is due to shear whereas in the outer unsheared zone propagation is due to compressive waves. the research results gives a method of predicting the radial position at which the flow changes, which coincides with the radius of action of the vibrator. experiment agree that the peak velocity of the vibration governs its efficacy, with radius of action increasing with increasing velocity. the work offers the potential to optimise the design and use of vibrators. teranishi et al. (1993) investigated theoretically the mean deformation resistance of fresh concrete under vibration by simplifying the vibration as a repeated static shear stress and using the bingham model to express the deformation behaviors of fresh concrete under static stress. as a result, when the vibration acceleration is greater than a certain value, the shear rate – shear stress relationship in the lower shear rate – range becomes a curve without a yield value, rather than a straight line as in the bingham model. gong et al. (2015) developed a uwb-based tracking method for real-time 3d tracking and visualization of concrete vibration effort during concrete placement. the research results indicate that the developed occupancy grid-based vibration effort visualization method can identify defective vibration practices. the research outcome will contribute to the improvement of concrete consolidation quality assurance methods. concrete-filled steel tubular columns have better structural performance than that of bare steel or reinforced concrete. for reinforced concrete columns, concrete compaction only affects the mechanical properties of concrete. but for concrete-filled steel tubes, it is well known that the interaction between steel tube and concrete is the key issue to understand the behaviour of this kind of column. the concrete compaction not only affects the properties of the core concrete itself, but also may influence the interaction between the steel tube and its concrete core, and thus influences the behaviour of the composite columns (han and yao 2003). scientists grabiec and piasata (2004) say that the big influence on the concrete’s resistance to freezing – thawing cycles is being made by the density and the compressive strength of the concrete. the outcome of this article was to find how different compaction time influences the density and compressive strength of hardened concrete. 81 journal of sustainable architecture and civil engineering 2015/2/11 portland cement cem ii/a-ll 42.5 r (ma) (a) (jsc akmenės cementas production) was used for the test. physical, mechanical properties and chemical composition of portland cement are given at the table 1. sand with the fraction of 0/4, bulk density of 1680 kg/m3 and fineness module of 3.2 was used as fine aggregate. crushed gravel with the fraction of 4/16 and bulk density of 1450 kg/m3 was used as the coarse aggregate. granulometric composition of aggregates is conducted according to lst en 12620:2013 and presented in table 2. plasticizing admixture based on policarboxile polymers glenium sky 628 (basf construction chemicals italia spa) was used with density of solution 1.06 g/ml. the total dosage of admixture was 0.5 % of cement. the concrete mixtures were prepared in 3 minutes by two stages in laboratory forced type conmethods table 1 physical, mechanical properties and chemical composition of portland cement cem ii/a-ll 42.5 r (ma) (a) table 2 granulometric composition of aggregates specific surface area, m2/kg 410 particle density, kg/m3 3110 dry bulk density, kg /m3 1220 water demand for normal consistency (by vicat), % 26.5 volume stability, mm 0.8 initial setting time, min. 195 compressive strength after 2 days / after 28 days, mpa 27.1/54.0 loss on ignition, % 5.05 insoluble materials, % so 3 , % 2.48 cl-, % 0.015 alkalis, calculated by na 2 o equivalent, % <0.72 radius of the sieve’s mesh, mm the amount of poured out material, % sand fraction 0/4 crushed gravel fraction 4/16 32.0 100.0 16.0 94.8 8.0 100.0 37.8 4.0 94.8 4.9 2.0 78.7 1.2 1.0 55.7 0.8 0.5 37.9 0.7 0.25 14.9 0.7 0.125 2.7 0.7 0 0.4 0.5 crete mixer zyklos rotating pan mixer zz 75 he. during the first stage cement, aggregates and 2/3 of water were poured into the moistened mixer and mixed for 2 minutes. while during the second phase, the remaining amount of water was poured with concrete admixture and concrete mixture was mixed for 1 minute. during the research, dry aggregates were used for concrete mixtures. cement and aggregates were dosed by weight while water and chemical admixture were dosed by volume. when preparing the concrete mixture, 90 % of water was instantly poured to the mix. super-plasticizing admixture was mixed with 10 % of water and poured into the mixer. the concrete specimens, columns of diameter about 106 mm and height about 1000 mm dimensions size, were formed in plastic angular tube and compacted by using poker vibrator enar dingo (frequency: 50÷60 hz, vibrations: 18.000 r.p.m.). concrete mixture was compacted by poker vibrator, when vibrating element was placed to the top part of the form. different time was used for compacting mixjournal of sustainable architecture and civil engineering 2015/2/11 82 ture in forms: 0, 3, 6, 9 and 12 s. the concrete mixture was compacted immediately after placing in the forms in such a way as to produce full compaction of the concrete with neither excessive segregation nor laitance. the specimens were kept for 28 days in forms at the temperature about 16° c. when specimens were removed from the forms, they were cut by100 mm. after cutting the specimens, we got 10 samples, cylinders of diameter about 106 mm and height about 100 mm dimensions size. the cut surfaces of samples were polished by abrasive stone. if surface was extremely rough, it was smoothed by cement mortar. the consistency of fresh concrete mixture was determined according to standard lst en 123502:2009, density – according to standard lst en 12350-5:2009. the density of hardened concrete was determined according to standard lst en 12390-7:2009, the compressive strength – according to standard lst en 12390-3:32009. microsoft excel program was used for identifying the best dependence of the dispersion of the density and comprehensive strength values of samples and equation’s empirical coefficients values. the concrete mix was designed for compressive cube strength at 28 days of approximately 30 mpa. the mix proportions presented at table 3.results table 3 composition of concrete mixture materials unit materials per 1m3 concrete mixture cem ii/a-ll 42,5 r (ma) (a) kg 333 water l 180 crushed gravel fraction 4/16 kg 868 sand fraction 0/4 kg 1058 glenium sky 628 (0.5 %) l 1.6 water and cement ratio – 0.54 technological properties of the concrete mixture were determined. mixture fulfilled class s3 (s3=(100–150)±30 mm) according to cone abatement. determined density of the mixture was 2230 kg/m3. from the prepared concrete mixture 5 specimens were formed in the shape of column with dimensions: diameter 106 mm, the height 1000 mm (fig. 1). fig. 1 the formed concrete mixture specimens, columns of diameter about 106 mm and height about 1000 mm dimensions size (a), the concrete samples of diameter about 106 mm and height about 100 mm dimensions size (b) a b 83 journal of sustainable architecture and civil engineering 2015/2/11 the dependence of the concrete samples’ (106 mm diameter and 100 mm height – h/ d=0.94) density on the duration of compacting is presented in fig. 2. from the presented graphic it could be observed, that the average values of the concrete samples’ density is in the range of 2130÷2190 kg/ m3. the highest average value of the density of the concrete samples (2190 kg/m3) was obtained when mixture was compacted for 3 seconds during the formation (h/d=9.4). as it was expected, the lowest average value of concrete sample’s density (2130 kg/m3) was obtained when mixture was not compacted during the formation (h/d=9.4). the dependence of concrete sample’s (h/d=0.94) compressive strength on the duration of the compacting is presented in fig. 3. the average values of compressive strength of the concrete samples were in a small range 30.3÷32.6 mpa. fig. 2 the change of density of concrete samples depending on the compacting time fig. 3 the change of compressive strength of concrete samples depending on the compacting time a) b) fig. 1. the formed concrete mixture specimens, columns of diameter about 106 mm and height about 1000 mm dimensions size (a), the concrete samples of diameter about 106 mm and height about 100 mm dimensions size (b) the dependence of the concrete samples’ (106 mm diameter and 100 mm height – h/d=0.94) density on the duration of compacting is presented in fig. 2. from the presented graphic it could be observed, that the average values of the concrete samples’ density is in the range of 2130÷2190 kg/m3. the highest average value of the density of the concrete samples (2190 kg/m3) was obtained when mixture was compacted for 3 seconds during the formation (h/d=9.4). as it was expected, the lowest average value of concrete sample’s density (2130 kg/m3) was obtained when mixture was not compacted during the formation (h/d=9.4). fig. 2. the change of density of concrete samples depending on the compacting time fig. 3. the change of compressive strength of concrete samples depending on the compacting time the dependence of concrete sample’s (h/d=0.94) compressive strength on the duration of the compacting is presented in fig. 3. the average values of compressive strength of the concrete samples were in a small range 30.3÷32.6 mpa. the tendencies of changes of the concrete samples’ compressive strength, when the duration of the compacting is different while forming the specimens h/d=9.4, corresponded to the tendencies of changes of the concrete samples’ density. while compacting concrete mixture with poker vibrator for 3, 6, 9 and 12 s, it had no significant difference for concrete samples’ compressive strength. it was not effective to compact concrete mixture with poker vibrator in plastic form, when vibrating element was placed to the top part of the form. the average values of density of concrete samples, a) b) fig. 1. the formed concrete mixture specimens, columns of diameter about 106 mm and height about 1000 mm dimensions size (a), the concrete samples of diameter about 106 mm and height about 100 mm dimensions size (b) the dependence of the concrete samples’ (106 mm diameter and 100 mm height – h/d=0.94) density on the duration of compacting is presented in fig. 2. from the presented graphic it could be observed, that the average values of the concrete samples’ density is in the range of 2130÷2190 kg/m3. the highest average value of the density of the concrete samples (2190 kg/m3) was obtained when mixture was compacted for 3 seconds during the formation (h/d=9.4). as it was expected, the lowest average value of concrete sample’s density (2130 kg/m3) was obtained when mixture was not compacted during the formation (h/d=9.4). fig. 2. the change of density of concrete samples depending on the compacting time fig. 3. the change of compressive strength of concrete samples depending on the compacting time the dependence of concrete sample’s (h/d=0.94) compressive strength on the duration of the compacting is presented in fig. 3. the average values of compressive strength of the concrete samples were in a small range 30.3÷32.6 mpa. the tendencies of changes of the concrete samples’ compressive strength, when the duration of the compacting is different while forming the specimens h/d=9.4, corresponded to the tendencies of changes of the concrete samples’ density. while compacting concrete mixture with poker vibrator for 3, 6, 9 and 12 s, it had no significant difference for concrete samples’ compressive strength. it was not effective to compact concrete mixture with poker vibrator in plastic form, when vibrating element was placed to the top part of the form. the average values of density of concrete samples, the tendencies of changes of the concrete samples’ compressive strength, when the duration of the compacting is different while forming the specimens h/d=9.4, corresponded to the tendencies of changes of the concrete samples’ density. while compacting concrete mixture with poker vibrator for 3, 6, 9 and 12 s, it had no significant difference for concrete samples’ compressive strength. it was not effective to compact concrete mixture with poker vibrator in plastic form, when vibrating element was placed to the top part of the form. the average values of density of concrete samples, depending on the time of compacting, were 1,01÷1,03 times higher compared with average values of the control samples. distribution of density and compressive strength of the concrete samples (h/d=0.94) depending on the location of the sample in specimen’s (h/d=9.4) height, when the duration of compacting is different is presented in fig. 4. results show, that the tendencies of distribution of concrete samples (h/d=0.94) density and compressive strength depending on the location of the sample in specimens (h/d=9.4) height are similar. at higher sample’s location, density and compressive strength were increasing. also it was noticed, that regardless the duration of the compacting of the specimens (h/d=9.4), values of density and compressive strength at 500-600 mm height were close to values of specimens journal of sustainable architecture and civil engineering 2015/2/11 84 taken at 100 mm height. that could be influenced by filling the forms with concrete mixture during the formation of the specimens: forms of 1000 mm height were filled with mixture in two steps and only after the mixture was compacted in forms. filing forms with several layers and instantly compacting separate layers could have more significant influence on density and compressive strength of hardened concrete. the best dependence of dispersion of values of concrete samples’ (h/d=0.94) density and compressive strength is presented in fig. 4. equations of dispersion of the results, empirical and correlation coefficients values are presented in table 4. correlation coefficient (pirson), which is evaluating the strength of linear relationship, and presented in the table 4, was calculated according to coefficient of empirical equation. the closer correlation coefficient is to 0, the better representation of the dispersion of values in the curve. according to the obtained correlation coefficient, it was determined which equation describes the best distribution of statistical data. from table 4 we can see, that values of dispersion of dependence of concrete samples density on the duration of the compaction time can be described by gradual, linear and parabolic dependencies. the values of correlation coefficient were in the range from 0.88 till 0.98. the relationship between the variables will be stronger a) compaction time, 0 s fig. 4 distribution of density and compressive strength of concrete depending on location of sample in the specimen’s height, when the duration of compaction time is different depending on the time of compacting, were 1,01÷1,03 times higher compared with average values of the control samples. distribution of density and compressive strength of the concrete samples (h/d=0.94) depending on the location of the sample in specimen’s (h/d=9.4) height, when the duration of compacting is different is presented in fig. 4. results show, that the tendencies of distribution of concrete samples (h/d=0.94) density and compressive strength depending on the location of the sample in specimens (h/d=9.4) height are similar. at higher sample’s location, density and compressive strength were increasing. also it was noticed, that regardless the duration of the compacting of the specimens (h/d=9.4), values of density and compressive strength at 500-600 mm height were close to values of specimens taken at 100 mm height. that could be influenced by filling the forms with concrete mixture during the formation of the specimens: forms of 1000 mm height were filled with mixture in two steps and only after the mixture was compacted in forms. filing forms with several layers and instantly compacting separate layers could have more significant influence on density and compressive strength of hardened concrete. a) compaction time, 0 s b) compaction time, 3 s c) compaction time, 6 s d) compaction time, 9 s b) compaction time, 3 s depending on the time of compacting, were 1,01÷1,03 times higher compared with average values of the control samples. distribution of density and compressive strength of the concrete samples (h/d=0.94) depending on the location of the sample in specimen’s (h/d=9.4) height, when the duration of compacting is different is presented in fig. 4. results show, that the tendencies of distribution of concrete samples (h/d=0.94) density and compressive strength depending on the location of the sample in specimens (h/d=9.4) height are similar. at higher sample’s location, density and compressive strength were increasing. also it was noticed, that regardless the duration of the compacting of the specimens (h/d=9.4), values of density and compressive strength at 500-600 mm height were close to values of specimens taken at 100 mm height. that could be influenced by filling the forms with concrete mixture during the formation of the specimens: forms of 1000 mm height were filled with mixture in two steps and only after the mixture was compacted in forms. filing forms with several layers and instantly compacting separate layers could have more significant influence on density and compressive strength of hardened concrete. a) compaction time, 0 s b) compaction time, 3 s c) compaction time, 6 s d) compaction time, 9 s c) compaction time, 6 s depending on the time of compacting, were 1,01÷1,03 times higher compared with average values of the control samples. distribution of density and compressive strength of the concrete samples (h/d=0.94) depending on the location of the sample in specimen’s (h/d=9.4) height, when the duration of compacting is different is presented in fig. 4. results show, that the tendencies of distribution of concrete samples (h/d=0.94) density and compressive strength depending on the location of the sample in specimens (h/d=9.4) height are similar. at higher sample’s location, density and compressive strength were increasing. also it was noticed, that regardless the duration of the compacting of the specimens (h/d=9.4), values of density and compressive strength at 500-600 mm height were close to values of specimens taken at 100 mm height. that could be influenced by filling the forms with concrete mixture during the formation of the specimens: forms of 1000 mm height were filled with mixture in two steps and only after the mixture was compacted in forms. filing forms with several layers and instantly compacting separate layers could have more significant influence on density and compressive strength of hardened concrete. a) compaction time, 0 s b) compaction time, 3 s c) compaction time, 6 s d) compaction time, 9 s 85 journal of sustainable architecture and civil engineering 2015/2/11 d) compaction time, 9 s depending on the time of compacting, were 1,01÷1,03 times higher compared with average values of the control samples. distribution of density and compressive strength of the concrete samples (h/d=0.94) depending on the location of the sample in specimen’s (h/d=9.4) height, when the duration of compacting is different is presented in fig. 4. results show, that the tendencies of distribution of concrete samples (h/d=0.94) density and compressive strength depending on the location of the sample in specimens (h/d=9.4) height are similar. at higher sample’s location, density and compressive strength were increasing. also it was noticed, that regardless the duration of the compacting of the specimens (h/d=9.4), values of density and compressive strength at 500-600 mm height were close to values of specimens taken at 100 mm height. that could be influenced by filling the forms with concrete mixture during the formation of the specimens: forms of 1000 mm height were filled with mixture in two steps and only after the mixture was compacted in forms. filing forms with several layers and instantly compacting separate layers could have more significant influence on density and compressive strength of hardened concrete. a) compaction time, 0 s b) compaction time, 3 s c) compaction time, 6 s d) compaction time, 9 s e) compaction time, 12 s e) compaction time, 12 s fig. 4. distribution of density and compressive strength of concrete depending on location of sample in the specimen’s height, when the duration of compaction time is different the best dependence of dispersion of values of concrete samples’ (h/d=0.94) density and compressive strength is presented in fig. 4. equations of dispersion of the results, empirical and correlation coefficients values are presented in table 4. correlation coefficient (pirson), which is evaluating the strength of linear relationship, and presented in the table 4, was calculated according to coefficient of empirical equation. the closer correlation coefficient is to 0, the better representation of the dispersion of values in the curve. according to the obtained correlation coefficient, it was determined which equation describes the best distribution of statistical data. from table 4 we can see, that values of dispersion of dependence of concrete samples density on the duration of the compaction time can be described by gradual, linear and parabolic dependencies. the values of correlation coefficient were in the range from 0.88 till 0.98. the relationship between the variables will be stronger when the correlation coefficient values is close to 1. it means, that variables are statistically dependent and based on the values of the correlation coefficient, there is a strong connection between variables. table 4. the dependence of dispersion of data compaction time, s properties of hardened concrete equation coefficients value of equation r-squared value correlation coefficient r a b c d 0 density y = a·xd 1953.9 0.0221 0.776 0.88 compres. strength y = a·xd 19.282 0.1171 0.682 0.83 3 density y = a·xd 2007.7 0.0221 0.956 0.98 compres. strength y = a·xd 18.776 0.1381 0.746 0.86 6 density y = a·xd 1970.2 0.0218 0.817 0.90 compres. strength y = a·x + b 0.1166 24.548 0.775 0.88 9 density y = a·x + b 1.3944 2099.6 0.905 0.95 compres. strength y = axd 15.907 0.1833 0.581 0.76 12 density y = a·x2+b·x+c 0.0126 0.7789 2155.3 0.842 0.92 compres. strength y = a·xd 22.657 0.0946 0.491 0.70 the dispersion of values of dependence of concrete samples compressive strength on the compaction time could be described by a gradual and linear dependencies. the calculated values of correlation coefficients are in the range of 0.70 to 0.88. it shows, that variables are statistically dependent and based on values of correlation coefficients – the relationship between variables is strong. compared with the influence of time of compacting the concrete mixture with poker vibrator on the density and when the correlation coefficient values is close to 1. it means, that variables are statistically dependent and based on the values of the correlation coefficient, there is a strong connection between variables. the dispersion of values of dependence of concrete samples compressive strength on the compaction time could be described by a gradual and linear dependencies. the calculated values of correlation coefficients are in the range of 0.70 to 0.88. it shows, that variables are statistically dependent and based on values of correlation coefficients – the relationship between variables is strong. compared with the influence of time of compacting the concrete mixture with poker vibrator on the density and compressive strength it can be noticed, that values of correlation coefficients’ showing dispersion of concrete samples’ density are higher then values of correlation coefficients’ showing dispersion of table 4 the dependence of dispersion of data c om pa ctio n tim e, s properties of hardened concrete equation coefficients value of equation r -s qu ar ed va lu e correlation coefficient r a b c d 0 density y = a·xd 1953.9 0.0221 0.776 0.88 compres. strength y = a·xd 19.282 0.1171 0.682 0.83 3 density y = a·xd 2007.7 0.0221 0.956 0.98 compres. strength y = a·xd 18.776 0.1381 0.746 0.86 6 density y = a·xd 1970.2 0.0218 0.817 0.90 compres. strength y = a·x + b 0.1166 24.548 0.775 0.88 9 density y = a·x + b 1.3944 2099.6 0.905 0.95 compres. strength y = axd 15.907 0.1833 0.581 0.76 12 density y = a·x2+b·x+c 0.0126 0.7789 2155.3 0.842 0.92 compres. strength y = a·xd 22.657 0.0946 0.491 0.70 journal of sustainable architecture and civil engineering 2015/2/11 86 concrete samples’ compressive strength. having longer duration of compaction time, correlation coefficients’ showing dispersion of concrete samples’ compressive strength are getting smaller when the duration of compacting is 6 s. when the duration of compaction time is getting longer, the density dispersion dependence values are changing from gradual, linear to parabolic. the duration of the compaction time, during the formation of the mixture (h/d=9.4), from 3 to 6 s can be considered as optimal variant. construction and building materials, 2005; 19(4): 319–325. http://dx.doi.org/10.1016/j.conbuildmat.2004.07.007 banfill p.f.g., teixeira m.a.o.m., craik r.j.m. rheology and vibration of fresh concrete: predicting the radius of action of poker vibrators from wave propagation. cement and concrete research, 2011; 41(9): 932–941. http://dx.doi.org/10.1016/j. cemconres.2011.04.011 gonen t., yazicioglu s. the influence of compaction pores on sorptivity and carbonation of concrete. construction and building materials, 2007; 21(5): 1040–1045. http://dx.doi.org/10.1016/j.conbuildmat.2006.02.010 gong j., yu y., krishnamoorthy r., roda a. real-time tracking of concrete vibration effort for intelligent concrete consolidation. automation in construction, 2015; 54: 12–24. http://dx.doi. org/10.1016/j.autcon.2015.03.017 grabiec a.m., piasta z. study on compatibility of cement – superplasticiser assisted by multicriteria statistical optimization. journal of materials proreferences cessing technology, 2004; 152(2): 197–203. http:// dx.doi.org/10.1016/j.jmatprotec.2004.03.020 gurskis, v. 2008. statybinės medžiagos [building materials]. kaunas: ardiva; 2008, 136 p. in lithuanian. han l.-h., yao g.-h. influence of concrete compaction on the strength of concrete-filled steel rhs columns. journal of constructional steel research, 2003; 59(6): 751–767. http://dx.doi. org/10.1016/s0143-974x(02)00076-7 khayat k.h., saric-coric m., liotta, f. influence of thixotropy on stability characteristics of cement grout and concrete. aci materials journal, 2002; 99(3): 234-241. mewis j., wagner n.j. thixotropy. advances in colloid and interface science, 2009; 147–148: 214– 227. http://dx.doi.org/10.1016/j.cis.2008.09.005 roussel n. a thixotropy model for fresh fluid concretes: theory, validation and applications. cement and concrete research, 2006; 36(10): 1797–1806. http://dx.doi.org/10.1016/j.cemconres.2006.05.025 conclusions 1 the average values of density of the concrete samples, depending on the compaction time, were 1,01÷1,03 times higher compared with control sample. 2 the duration of the compacting of specimens (h/d=9.4), during formation of the mixture, had more significant influence on the density of the specimens (h/d=0.94) but not on the compressive strength. 3 regardless the duration of the compacting of the specimens (h/d=9.4) during the forma-tion of the mixture, values of density and compressive strength of samples taken at 500600 mm height were close to the values of samples taken at 100 mm height. 4 density correlation coefficients were higher than compressive strength’s correlation coef-ficients. 5 having longer duration of compaction time, correlation coefficients’ showing dispersion of concrete samples’ compressive strength are getting smaller when the duration of compacting is 6 s. the duration of the compaction time, during the formation of the mixture (h/ d=9.4), from 3 to 6 s can be considered as optimal variant. arslan m., şimşek o., subaşı s. effects of formwork surface materials on concrete lateral pressure. 87 journal of sustainable architecture and civil engineering 2015/2/11 safawi m. i., iwaki i., miura t. a study on the applicability of vibration in fresh high fluidity concrete. cement and concrete research, 2005; 35(9): 1834–1845. http://dx.doi.org/10.1016/j.cemconres.2004.10.031 teranishi h., tanigawa y., mori h., watanabe k. rheological study on consistency of bingham liquid subjected to vibration. proceedings of the japan concrete institute, 1993; 15(1): 357–362. ramūnas pocius technologist jsc “peikko lietuva” master faculty of civil engineering and architecture, department of civil engineering technologies main research area concrete mixture technology address naglio str. 4a, lt-52367 kaunas, lithuania studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 350261 tel. +370 37 300479 e-mail: ramunas.poc@gmail.com lukas venčkauskas master faculty of civil engineering and architecture, department of engineering structures main research area concrete mixture technology, strength and stability of reinforced concrete structures address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: l.venckauskas@gmail.com mindaugas daukšys professor faculty of civil engineering and architecture, department of civil engineering technologies main research area concrete mixture technology, concrete mixture rheological properties, formed concrete surface quality address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: mindaugas.dauksys@ktu.lt mindaugas augonis assoc. professor faculty of civil engineering and architecture, department of engineering structures main research area durability of engineering structures, strength and stability of reinforced concrete structures address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: mindaugas.augonis@ktu.lt šarūnas kelpša phd student faculty of civil engineering and architecture, department of engineering structures main research area durability of engineering structures, strength and stability of reinforced concrete structures address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: sarunas.kelpsa@ktu.lt about the authors journal of sustainable architecture and civil engineering 2017/2/19 40 *corresponding author: rossano.albatici@unitn.it comparison of thermal comfort conditions in multi-storey timber frame and cross-laminated residential buildings http://dx.doi.org/10.5755/j01.sace.19.2.17531 rossano albatici*, alessia gadotti, giulia rossa, antonio frattari university of trento, department of civil environmental and mechanical engineering via mesiano 77, 38123 trento, italy received 2017/02/09 accepted after revision 2017/04/10 journal of sustainable architecture and civil engineering vol. 2 / no. 19 / 2017 pp. 40-48 doi 10.5755/j01.sace.19.2.17531 © kaunas university of technology comparison of thermal comfort conditions in multistorey timber frame and cross-laminated residential buildings jsace 2/19 introduction keywords: thermal comfort, timber building, monitoring campaign, questionnaires, post-occupancy evaluation. in recent years, timber construction systems have been increasingly used in multi-storey residential construction in europe (ceccotti 2008, green 2012, council e investments 2014). in line with this international trend is the choice of the trentino social housing company itea to build two five-storey multi-family apartment buildings in trento (italy) using two different timber wall systems. the two buildings are identical except for their structural system: timber frame (tf) and cross laminated timber (clt). they also have a reinforced-concrete core located at the centre of one edge of the rectangular plan of each building. the design and the construction of these two buildings are the result of an international collaboration between itea and the canadian social housing company quebec societè d’habitation in order to evaluate and compare timber construction systems for social housing from the two countries. since the two buildings have identical floor plans, layouts and finishes and differ only in their structural system, they present a unique opportunity for comparison of the two key forms of timber construction in terms of economic, engineering and indoor comfort issues. their dynamic behaviour under lateral loads has already been examined (reynolds, casagrande e tomasi 2016). this paper investigates the difference in indoor conditions and analyse the achieved thermal comfort by measuring physical parameters and surveying the occupants’ perception. the two structural systems used for the buildings represent two widely used but fundamentally different forms of timber construction. the sheathed stud-and-rail system of the first building, commonly referred to as light timber frame (tf), has been used for many years and can be used efficiently with prefabrication of elements, since fully sealed and insulated panels can be assembled in factory, lifted into place and connected to each other with hand tools on site. this form of construction is extremely lightweight, which gives the building low thermal mass and conse41 journal of sustainable architecture and civil engineering 2017/2/19 quently low thermal inertia. this can lead to a lack of thermal comfort, particularly in summer, due to temperature fluctuations. cross-laminated timber (clt), used to form the timber shear walls in the second building, is a comparatively modern building component. again, it can be highly prefabricated, and used with computer controlled cutting techniques to pre-cut openings for windows, doors and services to a high degree of accuracy. this system, known as ‘massive timber’, provides a higher thermal mass, if compared to the previous system. it is interesting, then, to investigate to what extent this difference of thermal properties affects the indoor conditions provided and the final users’ satisfaction towards the thermal environment. this experimental campaign falls into a broader policy adopted by itea to engage closely with the performance of the buildings they build and manage, in accordance with an increasing interest globally in building performance assessment and post-occupancy evaluation (poe). in the view of improving the quality and sustainability of buildings, poe has started to be more and more perceived as a natural part of project delivery but, in many cases, this procedure still proves difficult: poe has continued as a research activity, but for the most part designers, constructors and often their clients have not been very closely involved (bordass e leaman 2015). the main purpose of poe techniques is to investigate occupants’ reported levels of comfort and satisfaction and the degree to which they perceive their needs are being met by the building’s indoor conditions, through structured questionnaires and interviews carried out after 3-18 months of occupancy (hefce 2006). the collected documentation provides information about habitability, functionality, indoor comfort and real energy consumption and allows to minimize the design-built performance gap (chiu, et al. 2014). post-occupancy evaluation is therefore a good opportunity to create a feedback loop for architects, planners, and building design and construction professionals in order to learn how different building design features and technologies influence occupant comfort, satisfaction and productivity (gossauer und wagner 2007). moreover, building monitoring and surveys are meant to improve the cooperation between all the stakeholders involved in the design and building process and enhance their responsibility for the performance of the building. in the case here presented, with the poe it can be stressed that itea manages its building stock in an efficient and effective manner. in the present paper, the analysis of the thermal comfort in two apartments was carried out. a traditional approach was used, by measuring the thermal-hygrometric environmental parameters together with the distribution of a dedicated questionnaire to the occupants. measurements were carried out in accordance with uni en iso 7730:2006 and uni en iso 10551:2002. along with the monitoring campaign, in accordance with the post occupancy evaluation guidelines, users have been surveyed with questionnaires relating to the perceived thermal comfort and the satisfaction with the indoor environment. moreover, questions related to user behaviour, heating and cooling system management, and doors and windows opening are asked. finally, a dynamic simulation model of the apartments has been developed by modelling with the use of designbuilder software the geometry, the structure, the envelope and the mechanical systems. after having set the real outdoor temperature profile during the two periods of monitoring, the evolution of the physical thermal-hygrometric parameters and the comfort indexes has been simulated. characteristics of the selected apartments the apartments dispose of one, two or three rooms and have a net floor area varying from 40 m2 to a maximum of 88 m2. they are occupied by 13 young families with 2 or 3 children, 7 single person households and 8 two-people-households of one elderly person or single parent with a child (the apartments selected for the research project belong to the latter category). moreover, all the apartments have been evaluated and certified in the energetic classes a+ and methods journal of sustainable architecture and civil engineering 2017/2/19 42 b+ and they have reached the “silver” level of the arca certification system (arca 2014). both the buildings present the same underfloor radiant heating system and controlled mechanical ventilation system that guarantees air renewal and purification in buildings. the heating system is based on a centralized condensing boiler, with an outdoor reset control of eater supply temperature. the boiler produces the hot water that feeds the radiant floor system. during the heating period, the mechanical ventilation system provides fresh air to the dwellings (with a lower threshold of 18°c for the supply air temperature). however, the occupants can freely interact with the envelope by opening and closing the windows. the ambient temperature controllers are set to the constant value of 20°c during occupied time, with a setback temperature of 16°c. fig. 1 the north five-storey timber building fig. 2 the second floor plan and the apartment selected for the campaign (grey). the layout is the same for the two buildings an external view of the two buildings is shown in fig.1. the tested apartments are one per building, on the second floor, having same shape, dimension, number of occupants and exposure (south), as shown in fig. 2 and fig. 3. in the north (tf) building, the walls are made with 120 mm x 180 mm solid timber studs with osb sheathing panels, 18 mm thick, on both sides of the wall. a timber-concrete composite structure is used for the floors, connecting 100 mm x 200 mm glulam beams to a 50 mm thick concrete slab. in the south (clt) building, the walls are made with 5-layer clt panels with a thickness of 153 mm for the ground and the first floor and of 133 mm for the upper floors. floors are made with 5-layer clt panel with a height of 153 mm. 43 journal of sustainable architecture and civil engineering 2017/2/19 experimental campaign the experimental campaign was carried out in two different periods, two weeks during late winter (february-march 2016) and two weeks during early summer (may-june 2016). in each campaign, a microclimatic measurement system has been set the first week in the living room and the second one in a bedroom. together with the microclimatic station, thermal-hygrometric probes have been put in each room of the apartments. the following parameters were measured: _ air dry bulb temperature ta [°c]; _ globothermometer temperature tg, used to calculate the mean radiant temperature tmr [°c]; _ air relative humidity rh [%]; _ mean air velocity va [m/s]. the acquisition rate for each of the measured parameter has been set to 10 min. by means of these parameters, the predicted mean vote pmv and the predicted percentage of dissatisfied ppd were calculated. the following instruments by lsi-lastem form milan (italy) have been used: _ air temperature and rh% sensor with pt100 output for temperature (resolution 0.01°c, uncertainty of 0.1°c) and 0-1 vdc output for rh% (resolution 1%, uncertainty of ±3.5%); _ radiant termperature sensor with pt100 output (resolution 0.01°c, uncertainty 0.15°c); _ hot wire anemometer using one sample every 100 ms and update output every one sec, with a resolution of 0.01 m/s (uncertainty ÷0,5 m/s = na, 0,5÷1 m/s = ± (0,05+0,05 va) m/s, >1 m/s= ± (0,1+0,05 va) m/s) fig. 3 the apartment floor plan in the north tf building (a) and in the south clt building (b) a b journal of sustainable architecture and civil engineering 2017/2/19 44 questionnaire survey during the experimental campaign, the questionnaire has been distributed to the occupants, two persons for each apartment considered. the questionnaires were based on the one proposed by uni en iso 10551 with some modifications. three different questionnaires (a, b and c) have been developed to be submitted to the occupants. particular attention has been paid to the formulation of the questions, the choice of the evaluation scales and the general structure of the questionnaire, since these are the most significant factors affecting the response rate and the reliability of the answers. in particular, the a type has been filled out twice a day (in the morning and in the evening), while the b and c types only once a day, in the evening. the occupants were asked to analyse their indoor environment from different point of view: _ thermal sensation, _ thermal comfort, _ thermal preference, _ acceptability, _ tolerability, _ possibility of individual control of microclimate, _ satisfaction for individual control. the questionnaire is divided into four parts: _ first part: personal data (age, sex, …); _ second part: thermal survey (activity performed in the last 15 minutes; clothing; judgment about tolerability of thermal environment, eventual preference for different conditions) (questionnaire a); _ third part: personal habits and environment control (occupancy schedule; windows openings; thermostat temperature settings) (questionnaire b); _ fourth part: judgment about air movement, eventual preference for different conditions (questionnaire c). modelling a dynamic building simulation has been carried out in order to calculate the energy performance and the trend of the indoor main physical quantities, by using the software designbuilder. as weather file, an epw file (energyplus weather file) has been obtained from local forecasting data, in order to run a simulation as close as possible to real conditions. the apartment model has been subdivided in five thermal zones: living room/kitchen, corridor, bathroom, double bedroom and single bedroom. trends of air dry bulb temperature, mean radiant temperature, operative temperature and relative humidity have been extrapolated and the results have been generated at weekly, daily and hourly rate. as number of steps per hour for the simulation, it was decided to set a data acquisition every 10 minutes that is consistent with the acquisition rate of the sensors. expexted results the experimental campaign is of great importance because the real trend of the considered physical quantities in real condition of use are recorded and analysed. so, it is possible to compare the performance of the two apartments considering actual weather conditions and the behaviour of the occupants. furthermore, the questionnaire survey is necessary in order to define the indoor comfort perception of the users (that can be very different from what expected) and to correlate it with the data coming from the instrumental survey, originating the comfort indexes. the data recorded can also be used to calibrate the model of the building. in fact, dynamic energy models often suffer from output uncertainties due to the high level and precision of input required, and simulation results can be quite different from realities. once the model is calibrated, it is also possible to verify the coherence of the pmv and ppd indexes coming from instrumental survey, from questionnaires and from the dynamic model. after that, the model can be considered as a “virtual exact copy” of the real building and some parameters can be properly changed (materials, shape, 45 journal of sustainable architecture and civil engineering 2017/2/19 exposure, geometry and so on) in order to evaluate new solutions that could improve the users’ comfort conditions. this last part of the research is not presented here. results and discussion winter analysis by comparing the temperatures measured by the temperature probes, it can be noticed that temperatures are higher in the clt apartment with an average gap of 0.8 °c (see graph 1, on the top). set the clothing value to 0.8 and the metabolic activity to 1.3, pmv and ppd have been evaluated. due to a technical malfunction of the microclimatic station, some data are lacking, on days 20th, 21nd and after 23rd of february. for what concerns the clt apartment, pmv values lie mostly within the limits of the comfort zone for the category b, while in the tf apartment pmv values fig. 4 temperature and pmv profiles during a week of the winter experimental campaign (17th-26th february) exceed the lower comfort limit, with a general slightly cold/cold thermal sensation (see fig. 4, on the bottom). the ppd trend is consistent with the pmv trend, with higher values (up to 18%) in concurrence of the days where comfort limits are exceeded. what emerges from the data analysis is that temperatures decrease faster in the tf apartment: this is evident in fig. 5, where the segments connecting the maximum and minimum daily temperatures are steeper for the tf apartment. the tf building cools more rapidly if compared to the clt building, due to its lower thermal mass. summer analysis for what concerns the summer period, an analysis of the different temperature profiles has been conducted, in relation also with the external temperatures. it has been observed that during the first week of the experimental campaign, in may, the clt building presents higher indoor temperatures while the tf building cools off during night temperatures. on the contrary, in june, when the minimum temperature values increase of an average of 4.5°c, the clt massive building shows lower temperature thanks to its higher thermal time lag and lower decrement factor (0.023 for the clt wall in front of 0.388 of the tf wall), thermal transmittance being equal (see fig. 6 and table 1). fig. 5 temperature trend during a week of the winter experimental campaign (17th-26th february) journal of sustainable architecture and civil engineering 2017/2/19 46 survey results in table 2, the average results from the qualitative survey during winter period are reported. the response about acceptability is not present since the environment has always been reported by the occupants as acceptable rather than unacceptable. a 7-degree two-pole judgement scale is used for the thermal perception, from very cold (-3) to very hot (+3) comprising a central neutral point, whose value is zero, and for thermal preference, from much colder (-3) to much warmer (+3) with a central point of absence of change (0). a 5-degree scale is used for thermal comfort, from ‘comfortable’(0) to ‘uncomfortable’(5), and for tolerability, from ‘perfectly tolerable’ to ‘intolerable’. finally, the form for the acceptability statement is a binary structure ‘generally acceptable’/’generally unacceptable’. what emerge from the questionnaires is that the thermal perception, which is linked to the pmv, ranges within the comfort limits, except for the clt apartment during the second week, in which a value equal to 1 is registered. however, this sensation of warmth is fig. 6 temperature and pmv profiles during a week of the summer experimental campaign (13th-20th june) table 1 thermal properties of the external wall in the clt and tf buildings clt wall tf wall thickness [cm] 42,4 35,6 u [w/m2k] 0,156 0,157 f[h] 20,19 9,42 d 0,023 0,388 table 2 qualitative survey results for the winter period 16th-25th february 27th february-7th march clt apartment tf apartment clt apartment tf apartment morning evening morning evening morning evening morning evening clothing value [clo] 0,75 0,75 0,79 0,73 0,7 0,7 0,77 0,8 metabolic activity [met] 1,17 1,62 0,69 1,23 1,2 1,4 0,74 1,07 thermal perception 0,28 0,1 0,11 -0,25 1 1,12 -0,14 -0,17 thermal comfort 0,28 0 0,33 0,12 0 0,12 0,14 0,15 thermal preference 0,28 0 0,22 0,37 0,2 0,125 0,14 0,17 tolerability 0 0 0 0 0 0 0 0,17 47 journal of sustainable architecture and civil engineering 2017/2/19 not perceived by the occupants as a discomfort. this can be seen by the value of thermal comfort and of tolerability, which are pretty much equal to zero. moreover, this warmth does not provoke any preference for cooler conditions, as it can be seen by the all positive values of the thermal preference. it can be assumed in consequence that the condition of ‘slightly cold’ (as in the tf apartment) generates a more irritating sensation than the condition of ‘slightly warm’. the results from the qualitative survey during summer period, shown in table 3, show a thermal perception that present always positive values in a range of [0.33,1.25]. however, in correspondence of the maximum value of thermal perception, thermal comfort is equal to zero and thermal preference is positive. this means that the occupants perceive a slightly warm sensation, which nevertheless does not have an influence on well-being. table 3 qualitative survey results for the summer period 20th-27th mai 13rd mai-20th june clt apartment tf apartment clt apartment tf apartment morning evening morning evening morning evening morning evening clothing value [clo] 0,58 0,61 0,68 0,58 0,6 0,55 0,49 0,5 metabolic activity [met] 1,05 1,07 0,73 1,4 0,86 1,7 0,67 1,07 thermal perception 0,75 0,67 0,33 0,67 0,67 1,25 0,33 0,33 thermal comfort 0 0,33 0 0,33 0,33 0 0 0 thermal preference 0,25 0,33 0 -0,33 0,33 0,75 -0,33 -0,33 tolerability 0 0 0 0 0 0 0 0 despite the fact that both the buildings have proven to be comfortable, some differences were identified in the comparison of the indoor conditions in the two apartments. during the winter period, it has been observed that, when the outdoor temperature drops, the value of the indoor temperature decreases faster in the tf apartment than in the clt apartment, on average of 1.2°c against 0.6°c. thus, the building that cools down more rapidly is the one with lower mass, which can hardly reduce heat loss from the flat. by analysing the external temperature evolution during the summer period, it has been noticed that the maximum values are similar in the two weeks of campaign while the minimum are rather different: in may, the average temperatures are 4.5°c lower than in june. this has caused that in the first week of campaign the temperature is higher in the clt building while, on the contrary, in the second week, when minimum temperatures outdoor significantly increase, this trend reversed and temperatures are higher in the tf building. this is due to the significance of thermal parameters such as the thermal lag and the decrement factor in summer period. in fact, the thermal lag value is equal to 20 hours in the clt building and 9 hours in the tf building, and the decrement factor is higher in the tf building since this structural system is less able to store heat compared with the clt alternative. furthermore, it is important to draw the attention to the fact that, thanks to the questionnaires to the occupants, it was possible to know the different behaviour towards the heating system management and windows. this has helped to analyse the obtained results particularly with respect to the subjective users’ experience. the buildings’ occupants have reported a state of overall comfort with a perceived slightly warm sensation in both seasons, but this does not provoke a desire for lower temperatures. it means that both the tf and clt building systems can provide a suitable inner thermal comfort with very little difference regarding temperature trend in winter and summertime. the users do not seem conclusions journal of sustainable architecture and civil engineering 2017/2/19 48 references about the author to notice the differences, always expressing satisfaction and high tolerance also in periods with a limited small discomfort. it can be said that tf and clt different thermal properties, although influencing the inner trend of thermal quantities, do not seem to affect the indoor comfort conditions and the final users’ satisfaction towards the thermal environment. acknowledgment rossano albatici assoc. professor university of trento, department of civil environmental and mechanical engineering, trento, italy main research area eco-sustainable buildings; bioclimatic architecture; human comfort in indoor spaces address university of trento via mesiano 77 38123 trento italy tel. +39 0461 282622 e-mail: rossano.albatici@ unitn.it the authors acknowledge the assistance of the trentino social housing company itea, that funded the research activity. arca. regolamento tecnico nuove costruzioni. rev. 3.00. arca casa legno, 2014. bordass b. and a. leaman. making feedback and post-occupancy evaluation routine 1: a portfolio of feedback techniques. building research & information, 2015; 33 (4): 347-352. https://doi. org/10.1080/09613210500162016 ceccotti a. new technologies for construction of medium-rise buildings in seismic regions: the xlam case. structural engineering international, 2008; 18: 156– 165. https://doi.org/10.2749/101686608784218680 chiu l.f., lowe r., raslan r., altamirano-medina h. and j. wingfield. a socio-technical approach to post-occupancy evaluation: interactive adaptability in domestic retrofit. building research & information, 2014; 42 (5): 574–590. https://doi.org/10.1080/0961 3218.2014.912539 bslc. summary report: survey of international tall wood buildings. binational softwood lumber council; 2014. gossauer e. and a. wagner. post-occupancy evaluation and thermal comfort: state of the art and new approaches. advances in building energy research, 2007; 1: 151–175. https://doi.org/10.1080/17512549 .2007.9687273 green m. c. tall wood. the case for tall wood buildings. vancouver: canadian wood council; 2012. hefce. guide to post occupancy evaluation. westminster: higher education funding council for england; 2006. reynolds t., casagrande d. and r. tomasi. comparison of multi-storey cross-laminated timber and timber frame buildings by in situ modal analysis. construction and building materials, 2016; 102: 10091017. https://doi.org/10.1016/j.conbuildmat.2015. 09.056 uni en iso 7730, ergonomics of the thermal environment analytical determination and interpretation of thermal comfort using calculation of the pmv and ppd indices and local thermal comfort criteria; 2006. uni en iso 10551, ergonomics of the thermal environment assessment of the influence of the thermal environment using subjective judgement scales; 2002. alessia gadotti ph.d. student university of trento, department of civil environmental and mechanical engineering, trento, italy main research area indoor comfort in buildings; post occupancy evaluation address university of trento via mesiano 77 38123 trento italy tel. +39 0461 282667 e-mail: alessia. gadotti@unitn.it giulia rossa contractor university of trento, department of civil environmental and mechanical engineering, trento, italy main research area building monitoring; post occupancy evaluation address university of trento via mesiano 77 38123 trento italy tel. +39 0461 282667 e-mail: giulia.rossa@ unitn.it antonio frattari professor university of trento, department of civil environmental and mechanical engineering, trento, italy main research area zero energy buildings; buildings rating systems; building automation for the low energy consumption and for the universal design address university of trento via mesiano 77 38123 trento italy tel. +39 0461 282668 e-mail: antonio.frattari@ unitn.it 41 journal of sustainable architecture and civil engineering 2017/4/21 *corresponding author: eng.fp@frederick.ac.cy life cycle assessment of flat plate solar thermal collectors received 2017/06/08 accepted after revision 2017/11/23 journal of sustainable architecture and civil engineering vol. 4 / no. 21 / 2017 pp. 41-49 doi 10.5755/j01.sace.21.4.18299 © kaunas university of technology life cycle assessment of flat plate solar thermal collectors jsace 4/21 http://dx.doi.org/10.5755/j01.sace.21.4.18299 foivi-zoi morsink-georgali, angeliki kylili, paris a. fokaides* frederick university, school of engineering, 7 frederickou str., 1036, nicosia, cyprus introduction the environmental assessment of facilities and equipment used for the exploitation of renewable energy sources constitutes a major challenge of the environmental scientific community. studies conducted in this field aim to define manufacturing alternatives which could mitigate the negative environmental impacts. the purpose of this study is the implementation of a comprehensive life cycle assessment for the definition of the environmental performance of flat plate solar thermal collectors. in terms of this study four alternative manufacturing scenarios are examined and a comparative assessment of the findings of the individual analyses is performed. the interpretation of the lca findings leads to some useful conclusions concerning the improvement of the environmental performance of flat plate solar thermal collectors manufacturing. keywords: solar thermal panels, flat plate collectors, life cycle assessment. the ever increasing global temperature, the continued climate change in all stages and the enduring resource depletion has led inevitably to the usage of renewable energy sources and the manufacture of different devices that could help us to make a change or even to minimize what we have already caused in this planet. sun is one of the most primarily forms of energy, and therefore the conversion of solar energy into electricity could led us in the minimization of greenhouse gasses, in energy savings, the achievement of 2020 & 2050 energy targets, the halt of the rising global temperature and at the end in a life concluding in a sustainable environment. solar collectors are a kind of systems that concentrate and convert the solar power indirectly. life cycle assessment (lca) is an effective methodology to assess the energy and environmental impacts of these energy systems during their life cycle, including manufacturing, operation and end-of-life. lca is becoming a common way to make fair environmental comparison between materials or systems, due to its comprehensive method, which assesses and quantifies the environmental impact of a product or process over its entire life cycle, including manufacturing, operation and end-of-life. every manufacturing process entails a consumption of energy and raw materials as well as the release of pollutants. that is the most solid reason on why a lca is a prerequisite even for renewable energy sources. on this concept the european countries have focused their attention, considering the improvement of the eco-performances of products / services as a key point of the european environmental program. (european union, com 2010, 31) the accuracy of lca results is dependent though on the method chosen, the degree of disaggregation or detail in the data, and the quality of the data itself (crawford & treloar, 2004). the aim of this study is to evaluate the environmental impact of solar collector manufacturing system by investigating alternative manufacturing scenarios. the utilization of recycled aluminum journal of sustainable architecture and civil engineering 2017/4/21 42 as frame and back cover, much like copper as absorber’ s material allowed the comparison of their effect in the environmental performance of the final product on a “cradle to gate” approach. the steps of this analysis are mention briefly below: _ assessment of state of the art in lca of a flat plate solar collector _ description of the flat plate solar collector’s production value chain and processing technologies _ lca on this collector by using gabi software [process-by-process quantification of resource in-puts and environmental outputs] _ analysis and discussion this study is anticipated to provide useful insight to the scientific and environmental community concerning the methods and techniques which could lead to the mitigation of the environmental impact of the manufacturing process of solar thermal panels. theoretical background life cycle assessment principles lca, developed by the society of environmental toxicology and chemistry (setac) in the 60’s and defined by the iso14040 series (iso 14040:2006), is the most commonly used tool to determine the environmental impacts of a product or a service (tsilingiridis et al., 2004). lca examines material and energy inputs, emissions and other outputs throughout the life of a product (or process), including resource extraction/winning, transportation at all stages, manufacturing, assembly, energy embodied in the input of goods and services, installation and disposal/recycling (crawford & treloar, 2004). the international standards iso 14040-14043 provides the principles, the framework and the methodological requirements for conducting lca studies. carrying out an lca consists of four main phases (wenzel et al., 2000). _ goal and scope definition identifying the lca’s purpose and the expected products of the study, and determining the boundaries and assumptions based upon the goal definition. _ life-cycle inventory analysis quantifying the energy and raw materials inputs and environmental releases associated with each stage of production. _ impact assessment assessing the impacts on human health and the environment associated with energy and raw material inputs and environmental releases quantified by the inventory. _ interpretation analysis evaluating opportunities to reduce energy, material inputs, or environmental impacts at each stage of the product life-cycle. lca aims to facilitate a systems view in product and process evaluation (joshi 1999) and can be considered as one of the major approaches in the field of industrial ecology (guinée 2002). however, it should be mentioned that the results of lca are not absolute, since they are focus-specific and therefore cannot be directly transferred across countries or continents; furthermore, they are dependent on system limitations, assumptions and energy/resources availability. nevertheless, lca results can still be exploited for the comparison of alternative technical options, systems or processes (christoforou et al., 2016). the international standards provide little practical guidance resulting to sources of uncertainty like: _ data inaccuracy (due to errors and imperfection in the measurements) _ data gaps or not representative data _ structure of the model (as simplified model to represent the functional relationships) _ different choices and assumptions _ §system boundaries definition 43 journal of sustainable architecture and civil engineering 2017/4/21 flat plate solar thermal collectors solar thermal systems are an ecological way of providing domestic hot water. they are experiencing a high interest since the beginning of the last decade in many locations worldwide (eurobserv’er, 2010). its capacity in reducing energy load for domestic hot water is significant in locations with high irradiation level (de laborderie et al., 2011). solar thermal systems feed on a ‘‘clean’’ energy source. a comprehensive analysis of the environmen-tal performance of solar thermal collectors should consider their whole life cycle (battisti, r., & corrado, 2005). a critical phase from an environmental point of view is undoubtedly the collector production step. the glazed flat plate collector is a heat exchanger that converts the radiant solar energy from the sun into heat energy. it collects solar energy and uses that energy for solar water-heating systems in buildings, solar space heating and process heating applications. this type tends to be more cost effective for most residential and small commercial hot water applications due to their simple design, low cost, and relatively easier installation compared to other ones (ramlow & nusz, 2010). the five main construction components of a collector are: _ diaphanous solar safety glass the safety glass is translucent and allows high radiation yield to be received by the absorber. _ aluminum absorber a high selective absorber is used to maximize heat collecting efficiency, converting sunlight into usable heat. the absorber is usually welded to the copper riser pipes _ heater and riser pipes the header and riser pipes are usually brazed together in small distances to form a harp shaped heat exchanger that the solar system heat transfer fluid circulates through perfectly _ insulation glass wool insulation is usually used to the bottom and sides of the collector to reduce loss of heat _ solid profile frame the solid profile frame is used to protect the absorber plate and the entire element. flat plate collectors can heat the fluid inside using either direct or indirect sunlight from a wide range of different angles. they also function in diffused light, which is dominant on cloudy days as it is the sur-rounding heat that is being absorbed and not the light, unlike photovoltaic cells. how hot the circulating water gets will depend mostly on the time of the year, how clear the skies are and how slowly the water flows through the collector’s pipes (dones et al., 2003) previous studies conducted for solar thermal panels lca several studies have been conducted in the past, which addressed the environmental performance of solar thermal panels. some studies compare the energy savings among solar collectors by calculating avoided auxiliary use (rey-martinez et al., 2008, hobbi, a., & siddiqui, 2009) it is more common for solar thermal studies to examine ways to maximize the efficiency of the system, and increase the solar fraction this is because the embodied energy of the system is considered insignificant in comparison to the operational inputs (tsilingiridis et al., 2004). several studies provide a breakdown of material inputs by mass for solar thermal systems. among them are rey-martinez et al. (2009) and ardente et al. (2005). the latter provide a detailed analysis of the embodied energy and environmental impacts of a solar thermal system. this study is one of the few that examines all life cycle stages, including maintenance and installation, and gives a detailed material mass (kg) breakdown for collectors, storage tank, and support. it is also the only one to look at direct, embodied, and feedstock energies. kalogirou (2004) provides a highly detailed report outlining the mass of materials, embodied energy per mass of material, and carbon emissions. this study has journal of sustainable architecture and civil engineering 2017/4/21 44 drawn heavily from the above-mentioned studies in order to create a process-chain analysis and calculate carbon emissions for a solar thermal system on the test site. lca overview in terms of this study a cradle-to-gate lca analysis was conducted. the solar panel considered was the superfoil alusel solar collector of johnsun heaters ltd (johnsun, 2017). the data provided by the collector manufacturer cover the amount of anodized aluminum, copper, low-iron tempered solar glass, glass wool, ethylene propylene diene monomer rubber (epdm), high-density polyethylene (hdpe), and silicone, that is contained in a collector with an aperture area of 1.32m² (gross area is 1.48m²) and an empty weight of 21.4kg. the solar glass is tempered, but in contrast to the solar glass of the flat plate col-lector with a copper absorber, no anti-reflex-coating is applied. the aluminum/copper absorber has a selective coating of nickel pigmented aluminum oxide (bluetec eta plus an air-to-air vacuum coating process). the efficiency is 74.7%. the amount of electricity, tap water, solder and factory infrastructure used for assembly of the collector, as well as the amount of generated wastewater, is adopted from the flat plate collector with a copper absorber. the lca of solar thermal panel manufacturing was implemented based on the principles described in the iso 14040 standard (iso 14040:2006). to this end, the gabi soft-ware was used to model the panel manufacturing system and to investigate its environmental performance. the gabi database delivers full range life cycle inventories (lcis), which enable the use of various impact assessment methods. lca goal and scope definition the goal of this study was to evaluate the environmental impact of solar collector’s manufacturing sys-tem by investigating alternative manufacturing scenarios in a cradle to gate analysis. the usage of recycled aluminum as frame and back cover, much like copper as absorber’ s material allowed the com-parison of their effect in the environmental performance of the final product. to ensure that all the input and output from panel manufacturing are related, the analysis was performed based on a reference unit regarding the quantification of the environmental performances. the functional unit of one square meter of absorber area was used for the proper delineation of the inputs so as to be extracting the outputs. the following manufacturing scenarios were examined: methods _ manufacturing of aluminum-alloy frame and back cover (scenario 1) _ substitution of aluminum-alloy frame and back cover with recycled aluminum (scenario 2) _ substitution of aluminum absorber with copper absorber (scenario 3) _ combination of second and third scenarios adjustments (scenario 4) lca impact categories for the purposes of this study, the cml (2001) methodology, one of the most widely used impact assessment methodologies, was employed (laurent et al., 2014). cml method is the methodology of the centre for environmental studies (cml), university of leiden, and focuses on a series of environmental impact categories expressed in terms of emissions to the environment. the impact categories which were examined in this study are listed below: _ global warming potential (gwp 100 years) _ acidification potential (ap) _ eutrophication potential (ep) _ ozone layer depletion potential (odp, steady state) _ abiotic depletion potential (adp) _ freshwater aquatic ecotoxicity potential (faep inf.) _ marine aquatic ecotoxicity potential (maep) _ terrestric ecotoxicity potential (tep) _ human toxicity potential (htp) _ photochemical ozone creation potential (pocp) 45 journal of sustainable architecture and civil engineering 2017/4/21 life cycle inventory (lci) in table 1 the lci of the study is presented. the flow chart of the manufacturing process for scenario 1 is also presented in fig. 1. the main assumptions for the study lci are the following: _ aluminum back cover and aluminum frame based on the considered dimensions, the aluminum back cover mass was 8.4 kg and the aluminum frame mass was 3.6 kg. concerning the transportation of aluminum, this was imported results and discussion table 1 data inventory for the production of one solar thermal panel element material mass [kg] process source back cover aluminum 8.4 aluminum production pe international rolling recycled aluminum 2.4 recycling ingot casting rolling frame aluminum 3.6 aluminum production pe international extrusion recycled aluminum 1.04 recycling ingot casting rolling insulation glass wool 2.36 glass wool production literature [glass wool] risers copper 3.63 copper alloy pe international headers copper 1.2 extrusion pe internationalreeling cutting absorber aluminum 0.796 aluminum production pe international rolling blue eta plus coating reeling copper 1.019 copper production pe international rolling blue eta plus coating reeling safety glass float flat 11.8 flat glass production pe international cutting hardening from egypt to cyprus (distance 958 km). _ epdm (ethylene propylene diene elastomer) rubber epdm, used as a wedge between the sliding back sheet and the frame, had a mass of 0.01kg. the rubber is produced in cyprus. _ glasswool the total mass of the 5 cm thickness glasswool was 2.36 kg. glasswool is transported from greece to cyprus (distance 1117 km). _ riser risers are manufactured with coper. the total mass of the risers is 4.83 kg. copper is imported in cyprus from bulgaria (distance 1088 km). the machine used for the piercing of the copper pipes operates with a programmable logic controller (plc) (50w and less than 3sec per vent, 30sec per pipe) and compressed air that cleans the trims without to affect the conductivity of the pipes for the best soldering of pipes among them. for the soldering of the metals it is used a milwaukee caulk (silicone) gun c18 pcg/400 18v, with flexible battery system. _ absorber the absorber consists of 0.796 kg aluminum (1.019 kg of copper for scenario 4). the absorber material is imported in cyprus from germany (distance 2558 km). _ safety glass imported from greece, the safety glass has a mass of 11.8 kg. journal of sustainable architecture and civil engineering 2017/4/21 46 life cycle assessment (lca) in table 2 the flat plate solar thermal panels manufacturing system environmental impact data is provided. as it can be observed from the data, the impact categories of ad fossils (mj), matp (kg dcb equivalent), gwp 100 (i.e. the global warming potential in a time period of 100 years, measured in kg of equivalent co2), htp (kg dcb equivalent) present the higher values in the manufacturing process of solar thermal panel. with the first glance it can be concluded that as respect to all impact categories the best environmental performance scenario is the 2nd, which concerns the use of recycled aluminum for the cover back and the frame. although the environmental impact of the second scenario in indicators like ad fossils, matp and htp is relatively high, in association to the other two scenarios these are least. abiotic depletion (ad) potential is divided into two sub-categories, namely elements and fossil, and it is used to describe the reduction of non-renewable raw materials. ad elements indicator provides an evaluation of the availability of natural elements, like minerals and ores, while ad fossil indicator includes the fossil energy carriers, such as crude oil, natural gas and coal. even though all four scenarios have almost the same quantity for ad elements (scenarios 1 and 2 have the same result due to aluminum absorber and scenarios 3 and 4 due to copper absorber), this is not the case for ad fossils, where the scenario 4 displays the least environmental impact. fig. 1 flow chart of production process (scenario 1) table 2 solar thermal panel manufacturing systemenvironmental impactcomparative data m an uf ac tu rin g sc en ar io a d p e le m en ts [k g sb e q. ] a d p f os si ls [m j] a p [k g so 2 eq .] ep [k g ph os ph at e eq .] fa ep [k g d cb -e q. ] g w p [k g co 2 eq .] h tp [k g d cb e q. ] m a ep [k g d cb e q. ] o ld p [k g r 11 e q. ] p o cp [k g et ha ne e q. ] te tp [k g d cb e q. ] 1 2.9e-02 1.3e+03 5.9e-01 4.2e-02 1.7e+00 1.2e+02 4.5e+02 2.2e+05 3.1e-08 2.3e-02 3.0e-01 2 2.9e-02 4.1e+02 2.0e-01 1.8e-02 1.1e+00 3.3e+01 7.9e+01 3.7e+04 2.3e-08 -1.2e-03 1.3e-01 3 3.5e-02 1.3e+03 5.8e-01 4.1e-02 1.7e+00 1.1e+02 4.3e+02 2.1e+05 3.0e-08 2.2e-02 3.0e-01 4 3.5e-02 3.9e+02 1.9e-01 1.8e-02 1.2e+00 3.0e+01 5.7e+01 2.6e+04 2.1e-08 -1.6e-03 1.3e-01 47 journal of sustainable architecture and civil engineering 2017/4/21 a maximum ap value of 0.781 kg so2 equivalent and a maximum ep of 0.0549 kg phosphate equivalent respectively, were found for manufacturing scenario 1. as far as the toxicity potential impact categories (i.e. fatp, matp, ttp, and htp) are concerned, these were examined with the cml 2001 methodology, measured in kg dcb equivalent. specifically, with regard to the material of the back cover and frame of the solar panel, 33.94% (faep), 58.23% (ttp) lower values were found for manufacturing scenario 2 (recycled aluminum), compared to scenario 1 (aluminum alloy), and 88,12% (maetp)and 87.31% (htp) lower values were found for manufacturing scenario 4 (combination), compared to scenario 1. the scenario with the highest environmental impact in the oldp and gwp categories is the one involving the usage of aluminum-alloy (i.e. scenario 1). this highlights once more the significance of the manufacturing of the back cover and frame from a different material. pocp, measured in ethylene equivalents (c2h4eq.), which is an indicator of the ability of a solar panel to contribute to photochemical ozone formation, presented negative values for scenario 4 due to the negative environmental effect from voc emissions from the production of tropospheric o3. at high concentrations, o3 is hazardous to human health, but at lower concentrations it damages vegetation. the only way table 3 emissions of all four investigated scenarios emissions to scenario 1 scenario 2 scenario 3 scenario 4 air 2.1e+03 5.0e+02 2.1e+03 2.1e+03 fresh water 1.2e+06 1.0e+05 1.1e+06 1.1e+06 sea water 6.9e+02 9.4e+01 6.6e+02 6.6e+02 agricultural soil 3.1e-06 2.2e-06 3.3e-06 3.3e-06 industrial soil 2.8e-04 8.3e-04 2.8e-04 2.8e-04 to reduce ground-level o3 is to decrease precursor emissions. in table 3 the emissions of all four investigated scenarios are presented. according to this analysis, scenarios 3 and 4 produce the exact same emissions in all categories. from one point of view, the highest emissions -referred to air, fresh and sea wateramong the rest involved in scenario 1. on the other hand, as regards to the soil -agricultural and industrialscenarios 3 and 4 present the highest negative environmental impact. the lowest produced emissions are those of scenario 2. in order to evaluate the environmental performance of the investigated flat plate solar thermal panels, the energy balance of the end-products was estimated for each production scenario examined in this study (see fig. 2). as it can be observed from the data, the most energy intensive fig. 2 flat plate solar thermal collectors embodied energy journal of sustainable architecture and civil engineering 2017/4/21 48 material in scenario 1 is the aluminum used for the back cover and the frame, and as a result that was the main rea-son examining other scenarios. regarding scenario 2, the results are slightly different. the energy needs for manufacturing the back cover and frame are significantly lower (99.97%), due to the change of the material to recycled aluminum. float flat (safety glass) use most of the energy in this scenario. conclusions the scope of this study was to examine the environmental impact of different solar thermal panel manufacturing systems through a cradle to gate life cycle analysis and to provide representative data regarding the energy balance of the end-products. for this purpose, four different manufacturing scenarios were examined. in two of these, the back cover and frame of the panel were manufactured with either aluminium alloy (scenario 1) or recycled aluminium (scenario 2). in the third examined scenario, the absorber of the panel was manufactured from copper instead of aluminium and in the fourth scenario the combination of scenarios 2 and 3 was assumed. based on the results of the aforementioned scenarios, it is confirmed that the minimization of the usage of aluminium metal with recycled one can significantly affect the environmental footprint of a solar thermal panel. particularly aluminium accounts for over 40% of the embodied energy of the end product, whereas the use of recycled aluminium results to the significant reduction of this indicator. similarly the use of recycled back cover reduces the global warming potential of the frame from 1.2e+02 to 3.3e+01 kg co2 eq. the analysis also revealed that floating glass has a major contribution to the embodied energy of the panel, with over 50% of the total embodied energy. an evaluation of the results regarding the energy balance of materials assembled to a solar collector was also provided in this study, coming to terms of the recycled aluminium as a better solution than aluminium alloy. the application of the alternative metal materials in four manufacturing scenarios further allowed the evaluation of its performance in terms of its impact on the several categories examined within the cml 2001 methodology. the combination of the two adjustments together in one panel contributes to the best possible and least energy intensive scenarios. the authors would like to address their graduate to dr andreas ioannides, director of johnsun heaters ltd for providing of the required information for the implementation of the lci of the flat plate solar thermal collector manufacturing. acknowledgment commission of the european communities, sixth environment action program of the european community, environment 2010: our future, our choice. communication from the commission to the council, com 2010, 31 final ardente, f., beccali, g., cellura, m., & brano, v. l. (2005). life cycle assessment of a solar thermal collector: sensitivity analysis, energy and environmental balances. renewable energy, 30(2), 109130. https://doi.org/10.1016/j.renene.2004.05.006 battisti, r., & corrado, a. (2005). environmental assessment of solar thermal collectors with integrated water storage. journal of cleaner production, 13(13), 1295-1300. christoforou, e., kylili, a., fokaides, p. a., & ioannou, i. (2016). cradle to site life cycle assessment (lca) of adobe bricks. journal of cleaner production, 112, 443452. https://doi.org/10.1016/j.jclepro.2015.09.016 crawford, r. h. (2004). using input-output data in life cycle inventory analysis (no. ph. d.). deakin university. crawford, r., & treloar, g. (2004, january). assessment of embodied energy analysis methods for the australian construction industry. in anzasca 2004: contexts of architecture: proceedings of the 38th annual conference of the architectural science association anzasca and the international building performance simulation association (pp. 415-421). university of tasmania. de laborderie, a., puech, c., adra, n., blanc, i., beloin-saint-pierre, d., padey, p., ... & jacquin, p. (2011, may). environmental impacts of solar thermal systems with life cycle assessment. in world renewable energy congress-sweden (vol. 57, no. 14, pp. 3678-3685). linköping university electronic press, linköpings universitet. https://doi. org/10.3384/ecp110573678 references 49 journal of sustainable architecture and civil engineering 2017/4/21 eurobserv’er, solar thermal barometer, systèmes solaires le journal des énergies renouvelables n° 191, june 2009,2 solar thermal markets in europe trends and market statistics 2009, estif, 2010 guinée, j. b. (2002). handbook on life cycle assessment operational guide to the iso standards. the international journal of life cycle assessment, 7(5), 311-313. https://doi.org/10.1007/bf02978897 hobbi, a., & siddiqui, k. (2009). experimental study on the effect of heat transfer enhancement devices in flat-plate solar collectors. international journal of heat and mass transfer, 52(19), 4650-4658. https:// doi.org/10.1016/j.ijheatmasstransfer.2009.03.018 iso 14040:2006 environmental management life cycle assessment. johnsun solar heaters ltd. http://www. johnsun-solar.com.cy/index.php?key=solar&contentid=2. last accessed: 20 march 2017 joshi, s. (1999). product environmental life-cycle assessment using input-output techniques. journal of industrial ecology, 3(2-3), 95-120. https://doi. org/10.1162/108819899569449 kalogirou, s. a. (2004). environmental benefits of domestic solar energy systems. energy conversion and management, 45(18), 3075-3092. https://doi. org/10.1016/j.enconman.2003.12.019 kloepffer, w. (2001). life cycle assessment in industry and business. the international journal of life cycle assessment, 6(3), 184-184. https://doi. org/10.1007/bf02978739 koroneos, c. j., & koroneos, y. (2007). renewable energy systems: the environmental impact approach. international journal of global energy issues, 27(4), 425-441. https://doi.org/10.1504/ijgei.2007.014865 laurent, a., bakas, i., clavreul, j., bernstad, a., niero, m., gentil, e., ... & christensen, t. h. (2014). review of lca studies of solid waste management systems–part i: lessons learned and perspectives. waste management, 34(3), 573-588. https://doi. org/10.1016/j.wasman.2013.10.045 r. dones, t. heck, s. hirschberg, kernenergie. in: sachbilanzen von energiesystemen: grundlagen für den ökologischen vergleich von energiesystemen und den einbezug von energiesystemen in ökobilanzen für die schweiz, paul scherrer institut villigen, swiss centre for life cycle inventories, dübendorf, switzerland, 2003 ramlow, b., & nusz, b. (2010). solar water heating--revised & expanded edition: a comprehensive guide to solar water and space heating systems. new society publishers. rey-martínez, f. j., velasco-gómez, e., martín-gil, j., navas gracia, l. m., & hernández navarro, s. (2008). life cycle analysis of a thermal solar installation at a rural house in valladolid (spain). environmental engineering science, 25(5), 713-724. https://doi.org/10.1089/ees.2007.0115 tsilingiridis, g. m. n. k. g., martinopoulos, g., & kyriakis, n. (2004). life cycle environmental impact of a thermosyphonic domestic solar hot water system in comparison with electrical and gas water heating. renewable energy, 29(8), 1277-1288. https://doi.org/10.1016/j.renene.2003.12.007 wenzel, h., hauschild, m. z., & alting, l. (2000). environmental assessment of products: volume 1: methodology, tools and case studies in product development (vol. 1). springer science & business media. foivi-zoi morsink-georgali student msc programme in sustainable energy systems main research area environmental assessment of sustainable energy technologies address 7, frederickou str., 1036, nicosia, cyprus tel. +35722 394394 e-mail: st0010383@stud.frederick.ac.cy angeliki kylili phd candidate frederick university main research area environmental assessment of sustainable energy technologies and building materials address 7, frederickou str., 1036, nicosia, cyprus tel. +35722 394394 e-mail: res.ka@frederick.ac.cy paris fokaides lecturer school of engineering, frederick university main research area computational and experimental building physics, sustainable energy technologies. address 7, frederickou str., 1036, nicosia, cyprus tel. +35722 394394 e-mail: eng.fp@frederick.ac.cy about the authors 5 journal of sustainable architecture and civil engineering 2016/4/17 *corresponding author: jurate.kamicaityte@ktu.lt subjective identity of kaunas cityscape: research results and their relation with objective indicators of urban structure received 2016/10/19 accepted after revision 2016/11/30 journal of sustainable architecture and civil engineering vol. 4 / no. 17 / 2016 pp. 5-14 doi 10.5755/j01.sace.17.4.16458 © kaunas university of technology subjective identity of kaunas cityscape: research results and their relation with objective indicators of urban structure jsace 4/17 http://dx.doi.org/10.5755/j01.sace.17.4.16458 rūta ribelytė-knistautienė, jūratė kamičaitytė-virbašienė* kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania kaunas city identity formants were recently identified preparing kaunas city master plan in 2013. they are divided into four groups: natural, functional, iconic, and conventional symbols. designation of symbols depicting urban identity is inseparable from the city’s history, its culture, and urban development. due to associativity characteristic to human thinking, history of the specific locality is understood through its inherent natural environment, objects created by human, and culture or its living traditions. therefore, designating the objects forming city identity symbols there were evaluated the following key aspects: natural conditions and historical-cultural-urban development. however, evaluation of subjective identity and its relation with objective indicators (natural or man-made objects and their characteristics) of urban structure is a very important factor for creating inclusive, phyllo-topic public urban spaces, having distinctive and unique character, and this aspect was not widely analysed in kaunas city yet. the aim of the research is to establish links between the different levels of subjective identity of kaunas city and its separate urban typological areas (old town, new town, historical suburbs, residential areas developed in soviet times, and city peripheral suburban areas) and objective indicators of urban structure, and to propose possible ways of urban design improvement in the places with negative identity. the research method used is sociological survey. questionnaire is constructed employing the following theories: theory of historical-cultural artefacts (cole, 1998), theories of the city form and image of the city (lynch, 1984, 1960), and theory of sense of place (shamai and ilatov, 2005). theory of pattern language (alexander, 1977) was used to determine possible measures for changing negative place identity to positive. the results of the research let to identify the main objects of urban structure that are the most important to the identity of local and kaunas level cityscape, factors of the negative identity, ways of integration of the new objects into existing urban environment preserving and developing its identity, the main elements of the local cityscape mental map, and the levels of subjective identity according the theory of sense of place. there were proposed to use 7 patterns related with communities and public spaces for the development of the positive identity. the main conclusions of the research are that positive identity of the cityscape is created by public spaces, objects of cultural heritage, parks, and public buildings; the main factors of negative identity are the following: unmaintained and unsafe streets, abandoned buildings and public spaces, etc.; the majority of the respondents feel a sense of belonging, attachment and special emotions to a place both in the local and city levels. keywords: cityscape identity, sense of place, urban structure. journal of sustainable architecture and civil engineering 2016/4/17 6 introduction place/landscape identity consists of tangible physical identity (tangible components), activities, and the symbols, images and meanings (intangible components) associated with places/landscapes (relph, 1976). “there is no inherent identity to places: this is constructed by human behaviour in reaction to places” (osborne, 2001), i.e. reaction comes after visual-aesthetic-semantic perception. the scientific literature distinguishes between existential (place), spatial, personal, and cultural dimensions of landscape/cityscape identity concept (stobbelaar and pedroli, 2011) important to overall understanding and evaluation of landscape identity. considering these aspects of notion of landscape identity, we define cityscape identity as the synthesis of objective identity (determined by physical properties and characteristics of tangible urban environment) and subjective identity (determined by the psychophysiological and emotional mechanisms of human-beings) (povilaitienė and kamičaitytė-virbašienė, 2015). subjective identity of the cityscape is defined by the concepts of “city as a text – system of symbols” and “people’s feelings toward place”. evaluation of subjective identity and its relation with objective indicators of urban structure is a very important factor for creating inclusive, phyllo-topic public urban spaces, having distinctive and unique character. the aim of the research is to establish links between the different levels of subjective identity of kaunas city and its separate urban typological areas (old town, new town, historical suburbs, residential areas developed in soviet times, and city peripheral suburban areas) and objective indicators of urban structure, and to propose possible ways of urban design improvement in the places with negative identity. methods in order to clarify the relationship between kaunas cityscape subjective identity and objective indicators of the urban structure as a research object was chosen kaunas city residents and visitors opinion from different kaunas city urban typological areas (i.e. city historical parts (new town and old town), historic suburbs, city parts built during the soviet times, and the current suburban areas). in order to get the valid analysis results, research objects were selected specifically from kaunas city structure. the selection was carried out according to the following criteria: _ distribution of the objects according to the construction period and geographical location. in order to get more accurate data about interaction of the city urban structure and human emotions it is important to select the objects in different parts of the city both from geographical and construction period points of view. we selected the objects which location is different, i.e. objects that represent all the main city zones: the historic city, the historic suburbs, modernist districts built during the soviet times, and the city suburban areas prevailed by low-rise single-family housing. _ population. it is important to select objects that comparing with similar objects would have the largest population. this allows identifying the most typical elements of urban structure of the area that are perceived by the residents. _ spatial structure. the research objects are selected according to the building morphotype in the context of the common structure of the city. the main prevailing morphotypes are the following: the low-rise residential construction, multi-storey residential areas built in soviet times, historical/cultural heritage buildings (centre of the city), and areas of mixed development (historical suburbs). thus, in accordance with the selection criteria there were selected the following areas of the research: _ city historical part (city centre) – old town, new town; _ city historic suburbs – žaliakalnis; _ districts built during the soviet period – šilainiai neighbourhood; _ current suburban area – vaišvydava, romainiai. 7 journal of sustainable architecture and civil engineering 2016/4/17 the research was expected to confirm or disprove the following hypothetical statements: 1 identity of the place is a very important qualitative factor of living environment that is rep-resented by objective indicators of urban structure (natural or man-made objects and their characteristics) and the specificity of their relationship with the townscape subjective identity – emotional reactions and feelings of city residents and visitors to components of physical environment and their structures. 2 the individual elements of the urban structure plays an undeniable role in urban develop-ment processes, they shape both the identity of the whole city and its individual parts. the identity can be positive or negative. 3 the subjective identity of the cityscape is perceived by the residents and visitors in the way of reading city as a text (dominants, landmarks, important areas, etc.) and it relates people with a certain location by emotional connection. 4 it is possible to discern a provisional urban identity in the cityscape of a part of the city (urban form and its visual expression) that can fit in one field of vision. 5 the visual identity of the city is shaped both by the historic parts of the city, as well as newly built up areas together with the natural environment. the research method used is sociological survey. questionnaire is constructed employing the following theories: theory of historical-cultural artifacts (cole, 1998), theories of the city form and image of the city (lynch, 1984, 1960), and theory of sense of place (shamai and ilatov, 2005). theory of pattern language (alexander, 1977) was used to determine possible measures for changing negative place identity to positive. in order to find out public opinion there was conducted a questionnaire survey. the survey was organized in all of the chosen districts of the city (city centre, žaliakalnis, šilainiai, vaišvydava and romainiai). the questionnaire consisted of two parts: questions about the district where the respondent lives, and questions about the city of kaunas. the respondents answered to all questions actively articulating their observations, ideas, and valuable comments in open and semi-open questions. results total questionnaire survey involved 96 respondents. in old town and new town 22 people were interviewed. in žaliakalnis district there were interviewed 23 people, in šilainiai district 26 people, in suburban areas (vaišvydava and romainiai districts) 25 people. on average even 84% of respondents indicated that it is very important that a certain area has its own identity, is unique and easily recognizable. upon request to comment on his/her answer, there were named the reasons of identity importance (see table 1). people from different districts of kaunas city state that the area’s identity is an important factor of quality of living environment. it helps people to distinguish, describe the location, orientate in it, creates its overall image, making the area more easily recognizable identifiable. identity is important both to the city residents and visitors. the majority of the respondents give the priority to the positive identity of location, which according to the respondents has to be created by parks, objects of cultural heritage, public spaces, water bodies, museums, community events, etc. it is also revealed that the identity of the place is best perceived at the level of local perspective for the majority of respondents, and at the panoramic level of perspective – for the minority of respondents (see table 2). journal of sustainable architecture and civil engineering 2016/4/17 8 table 1 importance of cityscape identity to the residents in different kaunas urban typological areas old town/ new town žaliakalnis šilainiai vaišvydava/romainiai 80 % 87 % 81% 88% why? originality and exclusivity is important. it helps you to orient in the area. it is easier to locate any object. it is easier for resident to evaluate, in which part of the city he/she would like to live. identity is important for orientation, planning. because it gives singularity, charm and city residents can be proud of place where they live. because it is pleasant when your residential area has something exceptional. it is important aesthetically and culturally. old town/ new town žaliakalnis šilainiai vaišvydava/ romainiai kaunas city 9 % 23 % 30 % 8 % parks 19 % 11 % 25 % 9 % 20 % cultural heritage objects 10 % 9 % 6 % 3 % sacral buildings 13 % 13 % 14 % 7 % 12 % events, festivals and holidays 12 % 9 % 7 % 11 % squares, alleys, pedestrian streets and other public spaces 4 % academic buildings, complexes 1 % peculiar roads network (e.g. žaliakalnis streets “fan”) 1 % 5 % sports buildings and complexes 4 % 25 % shopping places 7 % 4 % 18 % 2 % 9 % memorial and monuments 5 % 6 % 2 % 7 % impressive and important public buildings 14 % 8 % 1 % 5 % 15 % museums 1 % 13 % 6 % water bodies 10 % 7 % 7 % 25 % 9 % a place that reveals the spirit of a place – aura, feeling of the place table 2 the main factors creating identity maximum values minimum values there were also distinguished the main factors shaping negative identity of the place. they are the following: streets with potholes, abandoned unattended buildings, lack of children’s playgrounds, lack of bicycle tracks, abandoned public spaces, etc. considering these aspects, it can be stated that there are no equipped places for cultural events, residents’ communication, festivals, gathering, recreation, etc. (see table 3). 9 journal of sustainable architecture and civil engineering 2016/4/17 old town/ new town žaliakalnis šilainiai vaišvydava/ romainiai kaunas city 13 % 20 % 8 % 24 % 32 % streets with potholes 16 % 13 % 8 % 8 % 13 % abandoned buildings 22 % 13 % 12 % 10 % 12 % neglected adjacent buildings 9 % 11 % 6 % 22 % 8 % lack of bicycle tracks 6 % 9 % 12 % 4 % 7 % not enough parking places for cars 6 % 6 % 4 % 8 % lack of events 3 % 6 % 19 % 8 % 8 % lack of children’s playgrounds, unmaintained children‘s playgrounds 9 % 2 % 8 % 12 % 3 % lack of pedestrianh paths, unmaintained pedestrianh paths 16 % 18 % 15 % 4 % 14 % abandoned, unattended public areas 2 % 8 % 3 % lack of green areas table 3 factors shaping negative identity of the place after a survey of old and new objects ways of harmonization and the development ways of the area, it can be stated that the new objects should be adapted to the current environment so that they stand out as little as possible or they can slightly expose in the current environment. this indicates that respondents appreciate their neighbourhood’s identity and mostly are against drastic changes of its architectural and urban environment; give priority to “evolutionary” not “revo lutionary” way of development (see tables 4 and 5). old town/ new town žaliakalnis šilainiai vaišvydava/ romainiai kaunas city 5 % 9 % 11 % 11 % 5 % … disappear in the existing environment 42 % 65 % 50 % 50 % 47 % … must be adapted to the existing environment 42 % 22 % 35 % 35 % 42 % … slightly expose in the current environment 11 % 4 % 4 % 4 % 6 % … completely distinguish from the existing environment table 4 ways of old and new objects harmonization old town/ new town žaliakalnis šilainiai vaišvydava/ romainiai 74 % 39 % 35 % 48 % protection a place without changing authenticity 5 % 13 % 17 % 11 % development of site-specific local business 10 % 4 % 24 % 10 % conversion, development of new functions 11 % 44 % 24 % 31 % development/creation of new objects table 5 possible development ways of the area journal of sustainable architecture and civil engineering 2016/4/17 10 summarizing the answers to the questions about the object/area influence to respondents’ feelings to the place and about respondents emotions to a particular location, we can clarify the fact that there are quite strong local communities: people feel special relation, loyal and belonging to the place, close to its goals (i.e. the respondents mostly identify that they feel a part of the community) because they feel safe in their living environment, there are a lot of green areas, places for leisure activities, aesthetic living environment, etc. people believe that public spaces – mostly green areas of the district reinforce positive identity (see tables 6 and 7). table 6 influence of certain object/area features to respondents‘ positive feelings to the place old town/ new town žaliakalnis šilainiai vaišvydava/ romainiai kaunas city 6 % 5 % 7 % 7 % 7 % social contacts and friendship 6 % 7 % 8 % 6 % 7 % developed infrastructure 8 % 7 % 4 % 5 % 7 % the events in the analyzed area 6 % 8 % 8 % 8 % 6 % feeling of safety 5 % 6 % 6 % 5 % 6 % psychological factors 6 % 8 % 7 % 7 % 7 % lifestyle 5 % 6 % 4 % 5 % 5 % active community in the area 6 % 4 % 4 % 5 % 6 % cultural heritage objects 7 % 10 % 6 % 8 % 8 % the ecological aspect – there are a lot of green areas 6 % 8 % 6 % 7 % 7 % acceptable quality of living environment 7 % 9 % 7 % 7 % 6 % aesthetical environment of microrayon 6 % 9 % 8 % 7 % 7 % attractive, quiet residential area 7 % 9 % 6 % 6 % 7 % there are locations for leisure activities, places to rest 6 % 1 % 6 % 6 % 7 % distance from the city center 6 % 1 % 6 % 6 % distance from work 7 % 2 % 7 % 5 % 7 % attractive and unkeeped public area old town/ new town žaliakalnis šilainiai vaišvydava/ romainiai kaunas city 12 % 11 % 12 % 13 % 13 % no feelings for this place 13 % 14 % 15 % 12 % 13 % i am located in this place, but i do not feel a part of it, do not feel connected with it 17 % 18 % 17 % 17 % 17 % i feel a sense of belonging for this place 17 % 21 % 17 % 18 % 17 % i feel a special relation, emotions to this place 16 % 25 % 16 % 17 % 16 % i feel loyal to this place, objectives of the place are close to me 12 % 7 % 11 % 12 % 12 % i participate actively in local community activities, i support it 13 % 4 % 12 % 11 % 12 % i feel commited to this place, can sacrifice myself for it table 7 levels of respondents interface with (emotions to) a particular location 11 journal of sustainable architecture and civil engineering 2016/4/17 according to k. lynch theory of urban form and theory of the image of the city there was given an open creative question to respondents: to draw a map of their residential neighbourhood. it was determined that up to 80% of the respondents draw paths or roads first (on average 45%). landmarks are in the second place (on average 19%), and nodes (public spaces) are in the third place (on average 18%). the paths or roads, landmarks, and nodes are very important for the residents of the district, i.e. significant objects in the district and their connections have the highest importance to the perception of the certain area. people who are less familiar with the district tend to perceive it through the topography, large areas, and the broad arrow connections (see table 8). table 8 perception of urban structure of the analyzed area old town/ new town žaliakalnis šilainiai vaišvydava/ romainiai 26 % 35 % 38 % 80 % draw paths/roads first 4 % draw limits first 26 % 9 % 23 % 12 % draw a quarter/district first 32 % 30 % 4 % 4 % draw nodes (public spaces) first 16 % 22 % 35 % 4 % draw landmarks (important objects, dominant) first the systemized results of the research showed the places with the highest negative identity in kaunas: ąžuolynas park, valley of songs, unmaintained inner spaces of residential blocks, abandoned city sport centres, etc. (fig. 1). fig. 1 the public spaces with the negative identity chosen by the respondents (ąžuolynas, 2016; dainų…, 2012, 2016; duobėtos…, 2013; kauko…, 2016) in order to determine possible measures for changing the negative place identity to positive according to ch. alexander “pattern language” technique there were selected 7 patterns from 253 relevant to communities and public spaces (12. community of 7000; 30. activity nodes; 31. promenade; 56. bike paths and racks; 57. children in the city; 69. public outdoor room; 106. positive outdoor space). in the table 9 there is proposed matrix of ways of changing negative identity into positive using particular patterns to eliminate specific factors of negative identity. journal of sustainable architecture and civil engineering 2016/4/17 12 table 9 recommended patterns from ch. alexander theory for changing negative identity to positive and possibilities of their application negative factors creating identity (from selected objects) th e in o rd in at e pe de st ri an pa th s, t he ir d ef ic ie nc y a ba nd on ed , u na tt en de d pu bl ic a re a l ac k o f ch ild re n’ s pl ay g ro u nd s a ba nd on ed b ui ld in gs , n ot eq ui pp ed p la ce s fo r re si de nt s co m m un ic at io n, fe st iv al s, ga th er in g, e tc . l ac k o f ev en ts , u na tt en de d / de so la te d pl ac es f o r th em t o o rg an iz e l ac k o f cy cl in g p at hs a nd cy cl e pa rk in g u nm ai nt ai ne d in ne r sp ac es o f re si de nt ia l b lo ck s u ns af e pe de sr ti an p at hs , la ck o f l ig ht in g a ba nd o ne d sp o rt s co m pl ex es pattern (communities, public spaces) 12. community of 7000 control of place for local community use as many natural and historical resources to highlight the local community community right to initiate, make decisions and carry on affairs 30. activity nodes create more as possible active operating units near each node to create space for communities band together area and node have to a mutually reinforcing each other 31. promenade managed public space for gatherings place should be create there where people lived 20 min. distance from it the main activity node should be connected to each other retains stability, movement 56. bike paths and racks integrated safe cycle tracks and footpaths system good lighting bicycle parking spaces in public paces, near public buildings 57. children in the city do not leave children unattended in the city safe hiking trails, connecting all parts of the city free, secure movement ensuring in the city playground for children 69. public outdoor room in major public spaces are a few pergolas gatherings of people, recreation, leisure 106. possitive outdoor space create limits for every space, then it will become more positive, cosily every area should be the same open, the same closed find in space different size and shape object – priority for diversity many green areas area easily identifiable and recognizable – a clear function 13 journal of sustainable architecture and civil engineering 2016/4/17 the research results let to identify the space design alternatives of urban environment according to the intensity of the designed changes that are the following: creating a new space, reconstructing the space, or developing the existing space. after selecting an appropriate space design alternative of urban environment, the main aim is to create a public space that would fulfil the needs of communities and society. this space should be an important and significant object of a certain part of the city. it should become the landmark, nodal point or dominant attracting people and ensuring their movement. it also should ensure further development of the identity to a positive direction, and prevent the formation of negative identity factors. in order to create such space there are proposed some aspects to consider while providing management measures: consistence with the urban environment, consistence with the natural environment, meaningfulness, symbolism, consideration of the community opinion, positive feelings to location, attachment to the place, function of recreation, entertainment function, reflection of city/district peculiarity, representation, coherence with infrastructure, attraction (fig. 2). discussion fig. 2 proposals how to create phyllo-topic space of urban environment _ explicitly, identity of the cityscape is a very important factor for the quality of living environment. the performed sociological survey confirmed the hypothesis that identity of the place helps people to distinguish, describe the location, orientate in it; creates its overall image, makes the area more easily recognizable identifiable both for its residents and visitors. it also helps to maintain and enhance the main characteristics of the preferred environment: legibility, complexity, coherence, and mystery. _ the cityscape identity is created mainly by the objects of cultural heritage, parks, public open spaces, and public buildings. it is also revealed that the identity of the place is best perceived at the level of local perspective. _ respondents appreciate their neighbourhood’s identity and are against drastic changes of its architectural and urban environment. they give priority to “evolutionary” and not “revolutionary” way of development. the majority of the respondents feel a sense of belonging, attachment, and special emotions to a place both in the local and city levels. _ there are also established the main factors of negative identity: poor condition of the streets, sidewalks, the lack of bicycle paths, abandoned public spaces, abandoned unattended buildings. conclusions journal of sustainable architecture and civil engineering 2016/4/17 14 in order to change negative identity to positive there are recommended certain patterns from ch. alexander theory: 12. community of 7000; 30. activity nodes; 31. promenade; 56. bike paths and racks; 57. children in the city; 69. public outdoor room; and 106. possitive outdoor space. _ considering the research results according to k. lynch theory of urban form and theory of the image of the city it can be stated that providing management measures the priority should be given to the most important objects of the city districts (landmarks and nodes): public outdoor spaces and buildings and connections between them (roads and paths). _ the results of this research could be a starting point for the further deeper analysis of subjective identity comparing different research units in the same urban typological area, elaborating the set of objective indicators related with the different levels of subjective identity and foreseeing the ways of the research results integration into urban design and planning decisions. references alexander c. pattern language: towns, buidings, construction. new york: oxford university press; 1977. ąžuolynas. 2016. available at: http://renginiai.kasvyksta.lt (accessed 14 september 2016). cole m. cultural psychology: a once and future discipline. harvard: university press; 1998. dainų slėnis. 2016. available at: http://renginiai. kasvyksta.lt (accessed 14 september 2016). dainų slėnis (kaunas) | įdomi vieta. 2012. available at: http://wikimapia.org (accessed 14 september 2016). duobėtos gatvės piktina skaitytojus. 2013. available at: http://www.delfi.lt (accessed 14 september 2016). kauko laiptų baseinas. 2016. available at: http:// renginiai.kasvyksta.lt (accessed 14 september 2016). lynch k. good city form. cambridge ma: mit press; 1984. lynch k. the image of the city. cambridge ma: mit press; 1960. osborne b. s. landscapes, memory, monuments, and commemoration: putting identity in its place. canadian ethnic studies journal, 2001; 33(3): 39-77. povilaitienė i., kamičaitytė-virbašienė j. theoretical premises of cityscape identity evaluation // citta 8th annual conference on planning research / aesop tg public spaces & urban cultures: generative places smart approaches happy people, 25th september, 2015: book of abstracts. p. 31. relph e. place and placelessness. pion, london; 1976. shamai s., ilatov z. measuring sense of place: methodological aspects. tijdschrift voor economische en sociale geografie, 2005; 96(5): 467-476. sporto halė kaune. 2016. available at: http://www. autc.lt (accessed 14 september 2016). stobbelaar d. j., pedroli b. perspectives on landscapes identity: a conceptual challenge. landscape research, 2011; 36(3): 321-339. about the authors rūta ribelytė-knistautienė master student kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research area research of cityscape identity, management, preservation and use of objects of cultural heritage. address studentu st. 48, lt-51367 kaunas, lithuania tel. +37065854226 e-mail: rutaribelyte@gmail.com jūratė kamičaitytė-virbašienė professor kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research area landscape visual quality analysis, evaluation and regulation, methods of planned activity or object visual impact assessment, analysis of social preferences evaluating landscape visual quality and use of the analysis results in territory planning, evaluation of the potential of urban structures, research of cityscape identity, expression of sustainable development conception in architecture, landscape architecture, town and territory planning. address studentu st. 48, lt-51367 kaunas, lithuania tel. +37061477082 e-mail: jurate.kamicaityte@ktu.lt journal of sustainable architecture and civil engineering 2017/4/21 82 characterization of ternary batched concrete parking lots on the ground containing saw dust ash and egg shell powderreceived 2017/10/22 accepted after revision 2017/12/28 journal of sustainable architecture and civil engineering vol. 4 / no. 21 / 2017 pp. 82-89 doi 10.5755/j01.sace.21.4.19331 © kaunas university of technology characterization of ternary batched concrete parking lots on the ground containing saw dust ash and egg shell powder jsace 4/21 alban chidiebere ogbonna*, mikailu abubakar department of civil engineering, waziri umaru federal polytechnic, birnin kebbi, pmb 1034 birnin kebbi gpo, birnin kebbi city, kebbi state, nigeria *corresponding author: alban.ogbonna@yahoo.com http://dx.doi.org/10.5755/j01.sace.21.4.19331 the quality of a concrete parking lots, floors or slabs is highly dependent on achieving a hard and durable surface that is flat, relatively free of cracks and at the proper grade and elevation. the properties are determined by the aggregate characteristics, cementitious materials and the mixture proportions. concrete industry is one of the largest consumers of natural resources due to which sustainability of concrete industry is under threat. the environmental and economic concern is the biggest challenge concrete industry is facing. this study addressed, the issues of environmental and economic concern through the use of saw dust ash and egg shell powder mixture as partial replacement of cement in concrete. hydraulic cement was replaced by the mixture of saw dust ash and egg shell powder at 5%, 10%, 15%, 20% and 25% by weight. the cylindrical concrete specimens were tested for compressive strength, flexural strength, splitting tensile strength, slump and density .the compressive strength of the specimens was evaluated at the 3rd, 7th, 14th, 28th and 56th days of age. the flexural strength and the splitting tensile strengths were evaluated at 14th and 28 days of age. the results obtained satisfied the minimum specifications of relevant standards and manuals. the study concluded that mixture of saw dust ash and egg shell powder is a suitable supplementary cementitious material and can satisfactorily replace hydraulic cement up to 20% by weight in the construction and maintenance of concrete parking lot placed on the ground. keywords: compressive strength, concrete parking lot, egg shell powder, flexural strength, saw dust ash, supplementary cementitious material. introduction according to aci 330r, (2008), aci 330.1m-14, (2015) and aci 360r-10, (2010), concrete parking lots range in size from small, such as at corner convenience stores, to medium, such as at multi-unit housing projects, to large, such as those for shopping centers and office or commercial developments. most parking areas include driveways, some of which need to accommodate relatively heavy loads. special consideration may be needed if access to dumpsters is to be included. accordingly, concrete parking lots are constructed with a wide variety of construction equipment, ranging from hand tools and vibratory screeds to large highway paving equipment or laser screeds. because of the relatively high stiffness of concrete pavements, loads are spread over larger areas of the subgrade compared with asphaltic pavements. as a result, thinner concrete pavements can be used for the same subgrade material. additional benefits of using concrete 83 journal of sustainable architecture and civil engineering 2017/4/21 to construct parking lots include the following: (a). concrete surfaces resist deformation from maneuvering vehicles; (b). concrete surfaces drain well with only minimal slopes; (c). concrete has relatively simple maintenance requirements; (d). traffic lane and parking stall markings can be incorporated into the jointing pattern; (e). concrete is minimally affected by leaking petroleum products; (f). the light-reflective surface of concrete can be efficiently illuminated with minimal energy requirements; and (g). concrete parking lots reduce the impacts of the urban heat island effect relative to those of asphalt parking lots by producing lower surface temperatures, thus providing a cooler urban environment and reducing ozone production. parking lots have most loads imposed on interior slabs surrounded by other pavements, providing some edge support on all sides. highway and street pavements carry heavy loads along and across free edges and are subjected to greater deflections and stresses. street and pavements are usually designed to drain towards an edge where the water can be carried away from the pavement (aci 330r, 2008, aci 330.1m-14, 2015 and aci 360r-10, 2010). concrete parking lots on the ground and slabs-on-ground are defined as: slabs, supported by ground, whose main purpose is to support the applied loads by bearing on the ground. the slabs are of uniform or variable thickness and it may include stiffening elements such as ribs or beams. the slab may be unreinforced or reinforced with non prestressed reinforcement, fibers, or post tensioned tendons. the reinforcement may be provided to limit crack widths resulting from shrinkage and temperature restraint and the applied loads. post-tensioning tendons may be provided to minimize cracking due to shrinkage and temperature restraint, resist the applied loads, and accommodate movements due to expansive soil volume changes (aci 330r, 2008, aci 330.1m-14, 2015 and aci 360r-10, 2010). fig. 1(a and b) show typical example of concrete parking lots and slabs on ground. in a study mohammad et al (2015), concluded that saw dust ash is a suitable material for use as a pozzolan, since it satisfied the requirement for such a material by having a combined (sio2+al2o3+fe2o3) of more than 70% and that concrete becomes more workable as the saw dust ash (sda) percentage increases meaning that less water is required to make the mixes more workable .this means that sda concrete has lower water demand. they opined that the compressive strength generally increases with curing period and decreases with increased amount of saw dust ash (sda). they suggested that only 10% substitution can be allowed at maximum and 5% substitution is adequate to enjoy maximum benefit of strength gain. cement –saw dust ash concrete vary with mix proportion in a similar way as those of normal cement concretes (with 0% sda) and the compressive strengths of cement-saw dust ash concretes increased with leanness of mix up to some level of leanness after which the strength reduced. the 50-day strength values of cement-saw dust blended concrete, sandcrete, and soilcrete are respectively 82-99%, 75-95%, and 74-96% of those for 100% cement concrete (ettu et al, 2013). early strength development was observed to be about 50-60% of their 28 days strength. saw dust ash concrete can attain the same fig. 1 concrete parking lot on the ground (a, b) a b journal of sustainable architecture and civil engineering 2017/4/21 84 order of strength as conventional concrete at longer curing periods. saw dust ash can be used as partial replacement of cement up to a maximum of 10% by volume (marthong, 2012). in a study sanjay and rahul (2016) concluded that 10% replacement of saw dust ash gives 4.89% and 8.70% increase in the compressive strength of concrete at 7 days and 28 days. gowsika et al (2014) concluded that replacement of cement paste with 5% egg shell powder + 20 % microsilica gives no significant reduction in compressive strength properties and yields similar flexural strength when compared with that of conventional concrete. in a study, anand et al (2017) concluded that the compressive strength of 20% eggshell powder concrete increases up to 19.5% than that of conventional concrete and the split tensile strength of 20% eggshell powder concrete increases to 5.16% than that of conventional concrete. the concrete compressive strength with egg shell powder as cement replacement material increases up to 15 percent without silica fume. addition of silica fume also enhances the strength but in economical point of view only the egg shell powder replacement is sufficient enough for getting higher strength (praveen, et al (2015). hydraulic cement is the most important and most expensive constituent of concrete, therefore the replacement of cement with certain percentage of these saw dust ash and egg shell powder to see their influence on slump, flexural strength and compressive strength at the same time reduces the cost of concrete and reduce the environmental hazard. these objectives justify the need for this research. cementitious materials the chemical analysis of the cementitious materials were carried out in line with the procedures specified in astm c114 – 15 (2015), astm d5370 – 14 (2014) and astm c311 / c311m – 17 (2017). aggregates the sand (fine aggregate) used for this study is locally available well graded river sand passing through sieve 4.75mm but retained in sieve 2.36mm, 1.18mm, 600 micron, 300 micron and 150 micron. crushed granites passing through sieve 31.5mm but retained in sieves 25mm, 18.75mm, 16.0mm, 12.5mm, 9.5mm, 6.25mm and 4.75mm was used as natural coarse aggregate (nca). the natural coarse aggregate (nca) and the fine aggregate were selected in accordance with the specifications of astm d 448 – 12 (2012), aci 201.2r-16 (2016).aci education bulletin e1-07 (2007), and aci education bulletin e1-16 (2016). concrete mix ratio the concrete specimens were batched at the mix ratio of 1: 2: 3 by weight of cementitious materials, fine aggregate and coarse aggregate and marked as shown in table 1. the concrete specimens were batched in line with the specifications of neh-nrcs part 642 (2009), aci 330r (2009), aci 330.1m-14 (2014), aci 360r-10 (2010), and aci 201.2r-16 (2016). materials and methods table 1 measuring and mixing proportions for the concrete specimens at 1: 2: 3 mix ratio concrete specimen mark percentage replacement of cement with sda and esp (%) water-cementitious materials ratio cementitious materials (kg/m3) fine aggregate (kg/m3) coarse aggregate (kg/m3)cement saw dust ash (sda) egg shell powder (esp) sd-es1 0 0.55 400 0.00 0.00 800 1200 sd-es2 10 0.55 360 20 20 800 1200 sd-es3 20 0.55 320 40 40 800 1200 sd-es4 30 0.55 280 60 60 800 1200 85 journal of sustainable architecture and civil engineering 2017/4/21 results and discussion aggregate properties sieve analysis, specific gravity and water absorption were conducted for fine aggregate, and coarse aggregate in accordance with the specifications of astm d448 (2012), cadot (2015), txdot (2015) and nysdot (2014). the aggregate impact value (aiv) test, aggregate crushing value (acv) test and los angeles abrasion value test were conducted for the coarse aggregate in line with the specified procedures in astm d448 (2012), cadot (2015), txdot (2015) and nysdot (2014). concrete properties the slump value of all the fresh concrete mixtures were evaluated immediately after batching. the compressive strength value of the concrete were evaluated on the 3rd, 7th, 14th, 28th, and 56th days of age. the splitting tensile strength value was evaluated at the 14th and 28th day age. the specimens used for the compressive strength and splitting tensile strength tests were cylindrical in shape and measured 150mm diameter and 300 long. the flexural strength value was evaluated at the 14th and 28th day age. the beam specimens used for the flexural strength test measured 150mm width, 150mm depth and 700mm long. depth to effective span ratio of 4 was maintained during the flexural test. the sump, compressive strength, splitting strength and flexural strength tests were carried out in line with the procedures specified in aci 330r (2008), aci 330.1m-14 (2015), aci 360r-10 (2010), aci 201.2r-16 (2016), cadot (2015), txdot (2015) and nysdot (2014). cementitious materials the hydraulic cement used in this study conform to the specifications of astm c150/ c15016 e1 (2016), astm c1157/c1157m-17 (2017) and aashto m85 (2016). the egg shell powtable 2 chemical composition of saw dust ash and egg shell powder. s/n oxides cement (%) esp (%) sda (%) 1. sio2 21.8 0.08 65.79 2. al2o3 6.6 0.03 4.88 3. fe2o3 4.1 0.02 2.01 4. cao 60.1 52.1 9.39 5. mgo 2.1 0.01 3.92 6. na2o 0.4 0.15 0.07 7. k2o 0.4 2.68 8. so3 2.2 0.62 0.98 9. loi 2.3 42.2 4.56 10. others 4.79 5.72 der was prepared in line with the specifications of aci 232.1r-12 (2012), and astm c618-15 (2015). the saw dust ash conform to the specification of astm c618 -15 (2015), aci education bulletin e3-13 (2013), fhwa-hif-16-001 (216), aci education bulletin e3-13 (2013), aci 232.2r-96 (2002) and aci 232.1r-12 (2012) for class f fly ash. according to fhwa-hif-16-001 (2016) and astm c618-15 (2015) ,class f fly ash is defined as having a sum of the oxides (sio2, + al2o3 + fe2o3) equal or greater than 70% and class c fly ash as having the sum of the oxides (sio2, + al2o3 + fe2o3 ) equal or greater than 50%. table 2 shows the chemical composition of saw dust ash (sda), egg shell powder (esp) and cement. aggregates characteristics the results of the gradation of coarse aggregate, and fine aggregate are shown in table 3. the results of the physical and mechanical properties of the coarse aggregate, and fine aggregate are shown in table 4. the fine and coarse aggregate properties conform to specifications of astm d448 (2012), cadot (2015), txdot (2015), nysdot (2014), aci 201.2r-16 (2016), aci education bulletin e1-07 (2007), and aci education bulletin e1-16 (2016). journal of sustainable architecture and civil engineering 2017/4/21 86 concrete properties table 5, shows the slump, densities, and compressive strength values of concrete at different percentage replacement of cement with a mixture of saw dust ash and egg shell powder. the densities and slump values increase with increase in percentage replacement of cement. there is no significant change in compressive strength values of concrete containing 0% to 20% replacement of cement with a mixture of saw dust ash and egg shell powder as shown in table 5 and fig. 2. concrete specimens containing saw dust ash and egg shell powder mixture show increase in splitting tensile strength and flexural strength values as shown in fig. 3 and 4. the compressive strength results of 0% to 20% replacement of cement with a mixture of saw dust ash and egg shell powder satisfied the minimum 28 days strength of 31n/mm2 to 41n/mm2 and 35n/mm2 to 41n/mm2 specified in aci 330r (2008), aci 330.1m-14 (2015), aci 360r-10 (2010), aci 201.2r16 (2016), cadot (2015), txdot (2015) and nysdot (2014) for standard and high performance concrete parking lots on the ground. the maximum compressive strength and density values occurred at 10% replacement of cement with sda and esp. table 3 sieve analysis results of coarse and fine aggregate table 4 physical and mechanical properties of the aggregate used sieve size (mm) coarse aggregate (initial weight = 1000g) fine aggregate (initial weight = 1000g) percentage retained (%) cumulative percentage retained (%) percentage passing/finer (%) percentage retained (%) cumulative percentage retained (%) percentage passing/ finer (%) 31.5 0.00 0.00 100 25.0 1.3 1.3 1.3 19.0 12.4 13.7 86.3 16.0 21.84 35.54 64.46 12.5 28.78 64.32 35.68 9.5 22.65 86.97 13.03 6.5 9.8 96.77 3.23 4.75 2.63 99.40 0.6 0.00 0.00 100 2.36 14.22 14.22 85.78 1.18 19.07 33.29 66.71 0.6 23.45 56.74 43.26 0.3 21.06 77.80 22.20 0.15 17.11 94.91 5.09 0.075 3.64 98.55 1.45 total (%) 99.4 398 98.55 375.51 aggregate specific gravity water absorption (%) aggregate crushing value (%) aggregate impact value (%) los angeles abrasion value (%) fine 2.633 1.434 natural coarse (crushed granite) 2.731 1.23 19.63 22.54 24.71 87 journal of sustainable architecture and civil engineering 2017/4/21 table 5 average compressive strength test results (fck) cube mark percentage replacement of cement with sda and esp (%) slump (mm) density kg/m3 3rd day n/ mm2 7th day n/mm2 14th day n/mm2 28th day n/mm2 56th n/ mm2 sd-es1 0 93 2432 17.10 25.20 30.58 37.21 44.81 sd-es2 10 111 2441 21.20 27.60 33.08 40.02 45.61 sd-es3 20 109 2440 17.08 24.50 29.30 36.08 42.32 se-es4 30 121 2437 13.40 19.80 24.60 30.37 36.86 fig. 2 relationship between the compressive strength (n/mm2) and curing age (days) fig. 3 relationship of the 14th and 28th days splitting tensile strength with percentage replacement of cement with sda and esp fig. 4 relationship of the 14th and 28th days flexural with percentage replacement of cement with sda and esp 8 figure 2: relationship between the compressive strength (n/mm2) and curing age (days). figure 3: relationship of the 14th and 28th days splitting tensile strength with percentage replacement of cement with sda and esp. figure 4: relationship of the 14th and 28th days flexural with percentage replacement of cement with sda and esp. 0 10 20 30 40 50 3 7 14 28 56 co m pr es si ve st re ng th (n /m m 2) curing age (days) 0% 10% 20% 30% 3,57 3,62 3,5 3,23 4,34 4,42 4,22 3,98 0 1 2 3 4 5 0 10 20 30 sp lit te ns ile st re ng th (n /m m 2 ) percentage replacement of cement with sda and esp (%) 14 days 28 days 4,65 4,71 4,58 4,54 6,05 6,12 6,15 5,67 0 2 4 6 8 0 10 20 30 fl ex ur al st re ng th (n /m m 2 ) percentage replacement of cement with sda and esp (%) 14 days 28 days 8 figure 2: relationship between the compressive strength (n/mm2) and curing age (days). figure 3: relationship of the 14th and 28th days splitting tensile strength with percentage replacement of cement with sda and esp. figure 4: relationship of the 14th and 28th days flexural with percentage replacement of cement with sda and esp. 0 10 20 30 40 50 3 7 14 28 56 co m pr es si ve st re ng th (n /m m 2) curing age (days) 0% 10% 20% 30% 3,57 3,62 3,5 3,23 4,34 4,42 4,22 3,98 0 1 2 3 4 5 0 10 20 30 sp lit te ns ile st re ng th (n /m m 2 ) percentage replacement of cement with sda and esp (%) 14 days 28 days 4,65 4,71 4,58 4,54 6,05 6,12 6,15 5,67 0 2 4 6 8 0 10 20 30 fl ex ur al st re ng th (n /m m 2 ) percentage replacement of cement with sda and esp (%) 14 days 28 days 8 figure 2: relationship between the compressive strength (n/mm2) and curing age (days). figure 3: relationship of the 14th and 28th days splitting tensile strength with percentage replacement of cement with sda and esp. figure 4: relationship of the 14th and 28th days flexural with percentage replacement of cement with sda and esp. 0 10 20 30 40 50 3 7 14 28 56 co m pr es si ve st re ng th (n /m m 2) curing age (days) 0% 10% 20% 30% 3,57 3,62 3,5 3,23 4,34 4,42 4,22 3,98 0 1 2 3 4 5 0 10 20 30 sp lit te ns ile st re ng th (n /m m 2 ) percentage replacement of cement with sda and esp (%) 14 days 28 days 4,65 4,71 4,58 4,54 6,05 6,12 6,15 5,67 0 2 4 6 8 0 10 20 30 fl ex ur al st re ng th (n /m m 2 ) percentage replacement of cement with sda and esp (%) 14 days 28 days journal of sustainable architecture and civil engineering 2017/4/21 88 the following conclusions were drawn at the end of this study. 1 a mixture of saw dust ash and egg shell powder gives good pozzolan and cementitious material and can used in ternary batched concrete parking lots on the ground. 2 the concrete batching and mixing proportion of 1: 2:3 of cementitious materials, fine ag-gregate and coarse aggregate gives cementitious content of 400kg/m3 and fine to total aggregate of 0.4. this satisfied the minimum cementitious content of 300kg/m3 to 360kg/m3 and fine to total aggregate ratio of 0.35 to 0.45 specified in aci 330r (2008), aci 330.1m-14 (2015), aci 360r-10 (2010), aci 201.2r-16 (2016), cadot (2015), txdot (2015) and nysdot (2014). 3 using a mixing ratio and proportion specified by relevant standards, concrete mixtures containing up to 20% saw dust ash and egg shell powder exhibit similar characteristics compared to non-saw dust ash and egg shell concrete. 4 the use of saw dust ash and egg shell powder as supplementary cementitious material in preparing ternary concrete mixtures in construction and maintenance of concrete parking lots on the ground should be encouraged. this leads to cost effective and environmental friendly construction. it also leads savings in the quantity of cement that would have been consumed and as such sustainability of the cement industry can be guaranteed. 5 concrete containing a mixture of saw dust ash and egg shell powder should be well compact-ed to give densities above 2400kg/m3 and above. above all the concrete must be prepared with well graded fine and coarse aggregate to give acceptable compressive strength values. conclusions aashto m85-16, standard specification for portland cement . american association of state highway and transportation officials, washington, dc, usa. 2016; http://www.transportation.org/m85-16. aci 330r. guide for the design and construction of concrete parking lots. american concrete institute. 2008; http://www.concrete.org/330r aci 330.1m-14. specification for unreinforced concrete parking lots and site paving. american concrete institute. 2015; http://www.concrete. org/330.1m-14 isbn: 978-194272-707-1 aci 360r-10. guide to design of slabs-on-ground. american concrete institute. 2010; http://www.concrete.org/360r-10 isbn: 978-0-87031-371-4 aci 201.2r-16. guide to durable concrete. american concrete institute. 2016; http://www.concrete. org/201.2r-16 isbn: 978-1-945487-39-2 aci 232.1r-12. report on the use of raw or processed natural pozzolans in concrete. american concrete institute. 2012; http://www.concrete. org/232.1r-12 aci 211.4r-08. guide for selecting proportions for high strength concrete using portland cement and other cementitious material. american concrete institute. 2008; http://www.concrete.org/211.4r. isbn: 9780870313141 aci 232.2r-96. use of fly ash in concrete. american concrete institute. 2002; http://www.concrete. org/232.2r-96 isbn: 978-0-87031-371-4 aci 304.4r-00. guide for measuring, mixing, transporting, and placing concrete. american concrete institute. 2000; http://www.concrete.org/304.4r-00. aci education bulletin e3-13. cementitious materials for concrete. american concrete institute. 2013; http://www.concrete.org/education bulletin/e3-13. aci education bulletin e1-07. aggregates for concrete. american concrete institute. 2007; http:// www.concrete.org/education bulletin/e1-07. aci education bulletin e1-16. aggregates for concrete. american concrete institute. 2016; http://www. concrete.org/education bulletin/e1-16v3. isbn: 978942727-75-0. anand b.a, ramprasanth a.a, and shanmugavadivu v.a. experimental investigation on partial replacement of egg shell powder in conventional concrete. international journal of cem tech research, 2017; vol. 10 (8), pp. 453-457. astm c150/150m-16e1, standard specification for portland cement. astm international, west conshohocken pa. 2016; http:// www.astm.org/c150 astm c618-15. standard specification for coal fly ash and raw or calcined natural pozzolan for use in concrete. astm international, west conshohocken pa. 2015; http:// www.astm.org/c618 astm c114 – 15. standard test methods for chemical analysis of hydraulic cement. astm international, west conshohocken, pa, 2015; https://www. astm.org/c114-15 references 89 journal of sustainable architecture and civil engineering 2017/4/21 astm d5370 – 14. standard specification for pozzolanic blended materials in construction applications. astm international, west conshohocken, pa, 2014; https://www.astm.org/d5370-14 astm d448-12 (2012). standard classification for sizes of aggregates for roads and bridge construction. astm international, west conshohocken, pa, 2012; https://www.astm.org/d448. cadot. standard specifications, department of transportation, california state transportation agency, state of california, usa, 2015; https:// www.dot.ca.gov/hq/standards. ettu, l. o, njoku, f. c, anya, u. c, amanze, a. p. c, and arimanwa, m. c. variation of opc-saw dust ash composites strength with mix proportion. international journal of advancements in research & technology, 2013; volume 2 (8). gowsika d, sarankokila s, and sargunan (2014). experimental investigation of egg shell powder as partial replacement with cement in concrete, 2014; vol. 14 92), pp. 65-68. marthong, c. “sawdust ash (sda) as partial replacement of cement,” international journal of engineering research and applications (ijera), 2012; vol. 2 (4), pp. 1980-1985. mohammad, i. m., syed, r. j., junaid, a. p., syed, a. n., and khubbab, f. m. partial replacement of cement by saw dust in concrete: a sustainable approach. international journal of engineering research and development, 2015; vol 11 (2), pp. 44-53. mohamed, a.m, dinesh k.m, milan c.j and vani, g. replacement of cement using egg shell powder. ssrg international journal of civil engineering, 2016; vol. 3(3), pp. 1-2. https://doi. org/10.14445/23488352/ijce-v3i3p101 neh-nrcs part 642. specifications for construction contracts. national resources conservation service, national engineering handbook. us department of agriculture, independence avenue, washington, d. c, usa. 2009; https://www.nrsc.usda.gov/part642 nysdot. standard specifications. new york state department of transportation, state of new york, 2014; https://www.dot.ny.gov/standards praveen, k.r, vijaya, s.r, and jose, r.b. experimental study on partial replacement of cement with egg shell powder. international journal of innovations in engineering technology, 2015; vol. 5(2), pp. 334-341. sanjay chugh and rahul bansal. study on saw dust as partial replacement with cement. international journal of engineering technology, science and research. 2016; vol. 3(4) pp. 126-130. txdot. standard specifications for construction and maintenance of highway, street, and bridges. texas department of transportation, state of texas, usa, 2014; https://www.ftp.dot.state.tx.us/standards. alban chidiebere ogbonna lecturer/researcher department of civil engineering, college of engineering, waziri umaru federal polytechnic, birnin kebbi, kebbi state, nigeria main research area pavement material engineering, traffic engineering and transportation engineering address: department of civil engineering, college of engineering, waziri umaru federal polytechnic, birnin kebbi, p.m.b 1034, birnin kebbi gpo, birnin kebbi city, kebbi state, nigeria tel. +2348039256430 e-mail: alban.ogbonna@yahoo.com abubakar mikailu lecturer/researcher department of civil engineering, college of engineering, waziri umaru federal polytechnic, birnin kebbi, kebbi state, nigeria main research area structural engineering, foundation engineering and concrete technology address: department of civil engineering, college of engineering, waziri umaru federal polytechnic, birnin kebbi, p.m.b 1034, birnin kebbi gpo, birnin kebbi city, kebbi state, nigeria tel. +2347031276736 e-mail: mikaabuba@gmail.com about the authors 73 journal of sustainable architecture and civil engineering 2015/4/13 heritage and sustainability: the matter of temporal shifting and narrativity in terms of urban development corresponding author: kastytis.rudokas@ktu.lt http://dx.doi.org/10.5755/j01.sace.13.4.13555 kastytis rudokas kaunas university of technology, institute of architecture and construction tunelio st. 60, lt-44405 kaunas, lithuania due to a raise of network-based society and interaction based decision making processes in contemporary world cultural heritage field must respond by being an active actor of holistic development. contemporary theory in heritage hardly sheds light on an adjacent processes happening in a field of economy, policy or alteration of social activity patterns. therefore, the following issue focuses on broader perception on cultural heritage field on the basis of the theory of the narrative. as pointed out in ricoeur’s (1985) linguistic approach towards narrative theory whereas he suggested to derive the past out of the future and thus to make our present to be a time of initiative in purpose to transpose history into a reasonable decision making. therefore, the narrative based approach towards an urban heritage (urban heritage here is to be a matrix where various of static structures of past, present and future meet and bias torrents of vivid social structure) contributes to a constant procedure of alteration that is likely enabled by the globallocal continuum. the issue is to claim that the latter alteration procedures (those that provide a growth of quantity in terms of human development) are a set of tools and methods used to rethink and interpret the past; yet the model of the future has been nearly designed. the use of narrativity in heritage is still novel trial to adjust the prevailing heritage discourse. however, the methodology of narrativity either enhances a field of cultural ecology that plays a key role to achieve a convivial place. on the basis of some urban patterns made by alexander as well as rethinking some researches of zaleckis, i suggest to take a look back to a politan city structure in order to preserve and transmit a relevant leftovers of a genotype of the polis into a megapolitan paradigm. to sum it up, the idea of ecological is to be understood as novelty or already designed future to our cities that turn smart. however, the shape or frame for this kind of future must be sculpted by rethinking our past and the processes of alteration inside the past. urban heritage (stable structures and vivid torrents) dwelled in a field of narrative may suggest a unique ways to turn about the physical environment in order to ensure convivial presence of cities as well as to prevent drastic alteration processes (that is already happening) and preserve a genotypic identity of the past. keywords: built-environment, heritage, kaunas modernism, sustainability, reversal coil, narrative. journal of sustainable architecture and civil engineering vol. 4 / no. 13 / 2015 pp. 70-79 doi 10.5755/j01.sace.13.4.13555 © kaunas university of technology received 2015/09/10 accepted after revision 2015/10/14 heritage and sustainability: the matter of temporal shifting and narrativity in terms of urban development jsace 4/13 the prevailing paradigm of science overall tends to merge different scholar subject in order to achieve higher productivity. the paradox that lays here is to be perceived is how nowadays society opposes itself in terms of mind and action. the mind and thought tends to be integral whereas simultaneously an action in everyday life, business or public administration remains niche based, solitary activity. the legacy of enclosed medieval guilds of craftsmen transforms itself during the industrial period and reaches our times almost intact in our terms of creative industries or, say, horizontal economic integration since so called specialization takes place. the new concept of smart specialization by regions seems to be nothing but extensions of former medieval street of separate sorts of craftsmen. the field of cultural heritage has been championed by many scholars to be integral part of network based society). however in many cases heritage and its urban artefacts turn to be type of commodity only in use for visual contribution to the urbanscape. heritage is employed as a testimony of somewhat possessing an outstanding universal value. an issue here, according to sophia labadi (2013) lays in terms of that is the value which is, by advanced western societies, imposed on rest of word via authorities such as unesco, icomos or others. the universality of value must be challenged in order to prevent unification via heritization. the paper suggest that artefacts of past together with surrounding temporal and cultural context needs to be active agent of decision making at present in order to ensure holistic sustainability of place. it is also to be relied on the spirit of the paris declaration (paris, 2011) as a crucial document that legislates aspiration to achieve more or less slower paced society. in the first part it challenges visual approach to heritage field by dividing ‘authorized discourse of heritage’ – well know concept by laura janesmith (2007) and phenomenon of heritage which tends to be described by natural origin. the authorized discourse is to be discussed in a light of age of enlightenment as well as rise and development of industrial society. the former aspects, as it is suggested, are featured with natural origin of past being active in temporal present. some examples are given. second part of an issue intends to explore heritage dynamics in broader context of sustainability of cultural ecology. relying on paul james idea of conservancy of positive element of past in present, the paper suggests phenomenon of reversal coil which is later expanded in merging with case study of sustainable development in kaunas during the interwar period. the study of sustainability and urban heritage relies on mythical model described in friedrich weinreb’s (1986) and reinhart koselleck’s (2005) time semantics. authors as well as levistrauss or nescolarde-selva (et. al. 2014) summarizes a temporal unity of past, present and future. thus the framework of heritage perception that must enliven the matter of sustainability is drawn by the mythical implication where heritage and its urban artefacts are to be splashes of implicit knowledge that need to be hermeneutically decoded in order to put them to conservancy status in order to achieve sustainability in long term urban planning. the phenomenon of the flat earth many references can be linked to the scholars championing heritage field moving from monuments to people thus maintaining ‘from below’ aspect. the concept suggests the possibility for the local communities to be turned into a decision making processes in a field of cultural heritage. thus the heritage itself has been transposed from a being a testimony of some great events of the past jet towards a festival (harrison, 2012) or a living heritage (poulios, 2014; wijesuriya, 2005). both approaches champion continuity and alteration processes as inevitable components of heritage itself maintaining that there is a relation between the user and object what is the most important part of heritage. however, for me, this implies a phenomenon where the heritage professionals and scholars try to deny the superimpositions that were made by western mindset during the raise of heritage field introduction methods results 75 journal of sustainable architecture and civil engineering 2015/4/13 in 19 cent. but at the same time they offer us new perceptions to be imposed on. the heritage as community art strategies maintained by rodney harrison, or past as living heritage at the many cases is just subtle phenotypes of the very previous monument-centered heritage-authorities discourse. heritage and its accessibility to the broader communities of society strongly correlate with market economy and its consumerist nature. if there was heritage as a matter of elites of society so was a satisfactory standard of living back in the beginning of 20 cent. in other words – by comparing heritage and simple commodities containing our everyday life experience, we see that the former as well as the latter now are at the near proximity to every human being in western society. at this case, we do have heritage field to be only poor reflection of prevailing discourses of time. after the heritage was authorized by the professionals in 19th century, the past have had less and less positive (neither direct negative) impact to the development of the society. there are several intercultural points to be emphasized. first, heritage, and how it was dealt with it, has lost its primal configuration where artefact or activity used to be inherited from generation by generation and applied to a changing condition but nevertheless itself remained active agent for future’s decision-making. as same as small retails were replaced by big super marked, that first occurred in france, and thus diminished both salesman and consumer interaction as well as salesman and owner interaction making the relation to be one way oriented. face to face interaction was about to turned around and linked towards faceless engagement. richard florida (2004:30) arguing with a famous robert putnam’s concept of ‘bowling alone’ emphasizes that what does nowadays society need is a quaziannonimity. thus, the quasiannonimity represents heritage where the transparency of its core meaning is to be blanked by discourse of authorities only maintaining what would be attractive to the consumer. susie west (2010:61-62) argues that the idea of heritage management in 18th century was mostly about to extend the ideals of antiquity. she stresses on an example of danish prince ludwig and sculptor bertel thorvandsen applied the method of anistylosis to restore ancient sculptures of antiquity. it may appear as a discourse that used to prevail in 18th century, however, individual relation with the artefact matters as well. the prince as well as bertel thorvandsen they both had transparent understanding and used to perceive an artefact via knowledge deriving from period of the antiquity as well as they were able to see antiquity’s meaning when it’s been imposed on the period of enlightenment. thus the individual relation with the artefact suggests that creativity of the current zeitgeist would support ‘values’ of historical period. as it is argued in hillier (1984:189-191), there are two level of urban genotypical interactions based on: 1st professional engagement and, 2nd based on bureaucracy’s configuration. professional level is enough to make one semantic step in order to solve an issue. bureaucracy requires many steps to be made tree-alike configurational system. the problem of bureaucracy in terms of heritage is that it supposes the industrial thinking patterns where only a big system can produce the commodity. the commodity itself then turns to be unified with others of its kind and ends up as a mass consumption thing. susie west’s example also has the other aspect that matters in our case. individual relation between user and the object may impose professional status of dealing with the property thus enabling creative re-use and re-think of that particular property. but on the other hand there is the very beginning of ‘having’1 concept in heritage to be revealed. the prince acts according the needs and trends of particular zeitgeist whereas antiquity and its legacy were intended to be had by contemporaries. hence, the raise of the new bourgeois imposed having and buying aspects into the public life. even the past could have been bought or even brought in by countries that never put a finger on a creation of properties. thus the classical period might be understood as the first paradigm in european society jet not having the past actively involved into a future decision making. yet the past was simulated and transmitted physically and mentally from ancient place to the place of current decision makers. 1 the definition is used according e. fromm work to have or to be? journal of sustainable architecture and civil engineering 2015/4/13 76 according to gregory ashworth (2011), there is to be three periods of heritage perception: he names it as conservation, preservation and heritage. the first dates back from 19th century up to charter of venice and the second from 1964 to approximately 90s and the latter are up to our days. anyway, at the most cases we could also name, that all these three meant to be part of conservation itself taking into account that conservation links to minimal interaction into properties tangible intangible spectrum of values (rodwell 2007: 187). at this case the conservancy agenda appears to be included into former two. for example to give here lays interesting case of renaissance emerges in late 14 century in florence. according to historian hans baron (1955:21-30,163-164), the raise of renaissance and its thinking patterns appeared in conflict with milan city and what it stood for. the ideals of florence were brewed in a process of thinking of greek polis but it was reused in order to apply it to the needs of present. thus, the heritage in is essence played a crucial role by adjusting economic, cultural and political configurations for the future. the former examples examinate mere pattern of purpose of the past in history of western civilization or, say, it reflects the very core ideas of bura charter’s (bura, 1999) terms of what conservation is. since the enlightenment age the presence of being was substituted by status of having and owning in terms of erich fromm (1990) concept. thus the past and heritage that transmits the that past in to the present for the future is only in use as a tool for exhibition and consuming, for claiming glory of the past of nation, rather than trying to improve qualities of state and bring them to the better future. there are important approaches towards nowadays heritage practice and theory. first is, that is heritage where intangibility matters first. intangible aspects, to me, look the most important because only tacit knowledge or, say, one implicit massage can be transferred just only by the intangible way. to see heritage property in full transparency means to discover splashes of tacit dimension suddenly appearing on precise attribute of that property. however in terms of authorized discourse of heritage, intangible heritage is still perceived more as a tradition that is no longer at works so thus one simply catalyzes repetition that is deceitfully supporting a tradition. the implicit dimension is gone, jet the exhibition of the lost but somehow alive to be born. the heritage of so called indigenous people illustrates the case in which heritage is no longer meant to be fuel for the future neither source of knowledge implicit or explicit no matter for redesigning it. the second aspect that appears it is urban and architectural heritage. the same issue of simulation and deceitfulness lay in a servancy of visuality. even the new architecture that is permitted to be erected in the historical area preserved by the unesco, is required to meet criteria and standards for roof top, scale and height (vienna memorandum, 2005). the visual authenticity and intact urban or architectural fabric do not actually suppose the quality of heritage management. as it is told in barthiel buchier (2013:188) research delving deeper for sustainability and heritage, city of cairo that was once the pearl of arab culture now is infamous with poverty, premature death and other unsustainable artefacts even if we do have old cairo area visually well preserved. the only benefit here to be tourism, however it turns about into a negative presence since tourist torrents have negative affect on local retail and service market for local people if the place is incapable for diverse economy yet (plaza 2008). hence here we do approach the issue that i call it a phenomenon of the flat earth. during the medieval period there was obvious that the planet earth was flat. in many cases this is true since we barely see and nether we do use round earth in our everyday life. heritage, when perceived in the light of authenticity of visuality and materials, therefore is poked to lose much of meaning which is hidden in cognitive aspects of heritage perception. since there is the past as well as many other processes of humanity consumed according to the rules of post/industrial market economy, this makes difficult to speak off heritage and sustainability relation. the complexity of the issue stands for heritage which is no longer tradition; as well a tradition is no longer heritage just because it is excluded off today’s zeitgeist context. however, relying on reinhart kosseleck’s (2003, 2004) periodization challenging ‘layers of time’ (zeitschichten) that insists that is every, even, most indi77 journal of sustainable architecture and civil engineering 2015/4/13 vidual act, still connects to other, that will be happening some when at the far future. the aim is neither to find junction nor to explain its configurations. the aim is to re-explore the methodologic framework in order to ensure sustainable approach stemming off the past agency. narrative approach of heritage and paul james ideas on sustainability denis rodwell (ibid:188) claims that conservation and sustainability both approaches correlate in order not to prevent any possible intervention or change but rather: ‘it implies a reorientation of it focused on new development that is additive and complementary, and significantly increased emphasis on maintaining, reusing, adapting, and enhancing the existing built stock and infrastructure – all within an overall framework that embraces the principles of the sustainable city and coordinated urban management.’ indeed, conservation as it is, means taking something of the past or present and used to project the future. the conservation approach neither does contribute in heritage field, nor meets requirements of alteration in a field of sustainability. opposing and more frequent definition used in heritage studies sure is preservation that is intended to prevent or/and avoid drastic shifts between past and present. in terms of the birth of renaissance there is seen a little of both approaches. in many cases the present had changed a lot in order to get rid of medieval structure of life. however, the gothic layout of the city as well as a configuration of merchandise or secularity and religion relation remained almost untouched. there were only new conditions of agency imposed on ongoing scotch of history. however, the past was active agent for present to be reassembled and for future to be redesigned. in this sense we can smell a conservancy playing major role for making the world of these days more sustainable. paul james (2015:23) stresses that sustainable conservation could be positive act by contrast – sustainable preservation supposes to be negative. author also points out the idea of mostly negative aspect of sustainability by arguing that most approaches don’t really target an issue. these are tackling side effects of activities, not trying to replace them with ones which would have been positive from the beginning. james (ibid:22) champion that: ‘sustainability is defined in terms of being able to carry on, endure or have a future. this is what, in our terms, can be called ‘negative sustainability’ – not negative in a sense of being bad but negative in a sense of just keeping a system or process going through acts of negation: reducing pollution, mitigating excesses, keeping law and order.’ cultural heritage as it is perceived today possesses a lot of negation too. heritage planning in terms of urban development has many aspects of forbidding alteration by implying sets of methodology how one is supposed to act in historical area. however, documents as vienna memorandum (op.cit) do not say about conservation of meaning and essence of idea in particular area. for instance it is to follow a historical layout, height and rooftop parameters only approach the visual environment. thus we here get back to phenomenon of a flat earth again. heritage neither is able nor it seeks conserve positive aspects of the past and integrates them into the future. however, the act of development and pursuit of progress is inevitable phenomenon of mankind therefore the active agency of the past and heritage is one of foremost aims to achieve in order to become sustainable race. at this point we can stem a parallel between concept of architectural heritage and ricouer’s notion on history throughout understanding of the narrative concept in philosophy. as ricoeur (1984:99) stresses: ‘the initiative in history does not belong to the document but to the question posed by the historian. this question takes logical priority in historical inquiry.’ in many aspects, architectural heritage is treated as facts exhibiting the various periods of the past. telling a story is a crucial moment for attracting torrents of tourists which, in its origins, has nothing to do with intended function of heritage property neither it has to do with sustainability. the consumerist origin of ‘authorized heritage discourse’ stems of history as it is narrated, according to ricouer, in advance, or just before the inquire took place. the author stresses that: ‘the past, in a natural process, is a past superseded and dead. in nature, each moment dies and journal of sustainable architecture and civil engineering 2015/4/13 78 is replaced by another one. on the other hand, the same event, known historically, survives in the present. someone may say that the past survives by leaving a trace, and we become its heirs so that we can reenact past thoughts. but survival and a heritage are natural processes; historical knowledge begins with the way we come into possession of them.’ (1985: 146). james idea of conservation of positive qualitative processes artefacts or activities seems to be relevant to the idea of heritage narrativity where the past is enacted into present and future not just for observation but rather for active presence. as renaissance analogy suggest, there has been so much of antiquity left in renaissance. however conservation is hardly imaginable. it is probably impossible to keep even single thing the same even if these are working precisely well. for instance the big religion has really strong identity have changed a lot just in order to adapt to context of surroundings. thus the crucial moment for conservation is to recognize the genotypic meaning of idea or property and to maintain the quality by intensifying its core meaning whatever the discourse claim at the particular moment. this is off course correlate with idea of progress. in terms of sustainable development the progress is needed just in order to achieve sustainability worldwide. therefore to explain the idea of heritage based progress we can rely on kantian notion on tradition. kant (kant in jonutyte 2010: 40), as it is common to the particular zeitgeist, did not treat a tradition as value to be followed by individual or community. in reverse, the civic freedom to him meant more than national freedom which according to him was an imposition of tradition. however, kant also believes that the progress or say learning and improvement is intended for nothing but achieve divine status of mankind presence that once existed in eden and was lost because of the sought of knowledge. thus knowledge makes humanity to fade way from god, but at the same time it also makes it closer to it. thus one, in order to come back where he was one step ago, now needs to travel across the globe. the particular notion relies on moral dogmas of enlightenment which was off course a starting point of heritage consumption. however it is still explains heritage based progression that is designed to achieve a sustainability of mankind. therefore, taking into account james notion of conservation and ricouer’s concept of illusory history and heritage as a natural process, we can draw a theoretical method of bringing past to a role of active agent. one of approaches may rely on the method i call the reversal coil. the reversal coil explains how once unprogressive past can turn into a solution of the future. in order to set a course for coils direction there is hermeneutic inquire needed. in terms of sustainability and urban development the beginning of 20th century could be once again announced as time of internal combustion engine. there was detroit that was no. 1 city in production of cars and therefore it featured and compiled par excellence industrial architecture designed by the architect of detroit albert kahn. even though detroit is barely the case since we focus on the massive automobilization, we can see that, for instance, chicago which sprawl was based on more administrative function of business rather than on pure industry maintain its position as financial center of usa. however, even the most distant towns and cities of world remained less automobilized. and after more or less half century the most progressive cities now try to get rid of cars at least in the central areas. however, example of automobiles is only one case of the reversal coil. recognizing at which point the coil needs to be brought back to the previous or even earlier paradigm and then, after it is recognized and approved by interdisciplinary council of professionals – then that quality or even physical artefact needs to be conserved and coherently integrated into a new context in order to achieve both sustainability and active agency to the past. it has been mentioned the urban sprawl of chicago which might be seen off topic. however chicago was not only the accidental place where sudden business processes just happened. the big impact was made by chicago school of sociology and its thoughts on socio-economic aspects of living. one of the pioneers of cultural ecology jacob riis (riis in parker 2004:43) believes in a potential that is hidden in lower social classes. unlike karl marx who championed an existence of 79 journal of sustainable architecture and civil engineering 2015/4/13 slavery, riis saw that constant upgrades of lower to higher class might be the answer for common good. nevertheless, james (ibid:4-5) argues that melbourne was awarded as a one of the most livable city of the world, but according to him: ‘if all city residents across the globe consumed at the rate of the world’s most livable cities the planet would be in catastrophic trouble.’ thus the reversal coil might be the key method for developing areas which usually tries to mimic the leading ones. instead of that these may rely on its past by trying to find there splashes of tacit knowledge appearance that can make impact towards better future. it off course implies elements of autarchy in cultural background in terms of management of places. case study: heritage of kaunas interwar architecture and its splash of sustainability that was not really meant by the contemporaries. giambatista vico, an italian thinker was able and tended to perceive different processes ongoing on different context as one entity (in jonutyte ibid: 37). for instance, vico stresses that there is no statehood possible to happen without a church as well as philosophy can’t exist without statehood. implicit perception offers that there is temporal and linear approach towards philosophy stemming out of religion. however according to a logical perception of time all these three processes coexist in on temporal point. as it is said in jonutyte (ibid.) all three of qualities are consisting into each other. the 17th century ideas moved towards 19th and 20th centuries at some points. for instance, insight of nicola tesla or albert einstein often suggested pre-networkist idea if not mentioning karl marx and his ambitious perception how slavery as socioeconomic class was a main cause for industrial society to rise. logical vista of different things and processes causing other processes or things that, at the first glance, can’t have anything in common, was championed by kosseleck and others. as it is offered by kerstin barndt (2010:6) regarding to ‘dead’ landscapes of industrial period: ‘the exhibitions of postindustrial transformation offer glimpses into layers of time and history that undermine the idea of progress—a master trope of nineteenth century museum narratives—and replace it with a new sense of being in time as an affective relation to the multiplicity of history and memory’. the idea of art exploring transparent junction of past into the future might be crucial; however the industrial ruins converted into exhibition properties might seem consumerist. nevertheless challenging the idea of progression might appear as an issue of reversal coil where lack or absence of industry during the industrial age might seem as a contemporary progress. delving deeper into kaunas interwar (1919-1940) cultural, economic and urban period we are able to see a splash that carries a tacit experience of sustainability. after vilnius the historical capital of lithuania was lost to poland during the 1918-1919 lithuanian-polish war, the capital moved to kaunas pro tem. there was complex of architectural-urban ideas raised on national style of lithuanian architecture as well as many thoughts of modern movement in press. however kaunas would never meet requirements of pure modern movement because its low scaled, slightly decorated buildings that are flowing somewhere between art deco and german functionalism. urban dimension here is slow-paced either. there were almost no build up by integrally planned quarters and areas. it raised one by one thus revealing and continuing a traditional building pattern of pre-industrial paradigm. however the alteration of genius loci during the interwar in kaunas was major. from the militarist province of russian tsardom, kaunas turned into a peculiar european polis. industry was, off course, important for city to sustain, but in a light of other european capitals or major cities of that time, we could not claim that kaunas development was industrial based. hence, importance of kaunas modernism lies in two-fold dimension of heritage sustainability. first off, kaunas modernism reveals continuity and slow-paced alteration of genius loci of interwar. by claiming slow-paced i stress that kaunas interwar period was a peculiar urban-architectural journal of sustainable architecture and civil engineering 2015/4/13 80 phenomenon whereas a culture that changed, at the first glance, very little essentially changed everything. whereas other towns and cities (zlin or brno in czech republic, or gdynia in poland) who were built almost from a scratch kept using variation of german functionalism and thus became signs of modernism pervading worldwide which lead to the definition of international style that is common to many. at this point, kaunas modernism was also influenced by functionalism aesthetics, however at the most cases final result of design remains very local or even baroque. so kaunas modernism is kind of contradiction to the rest streams of momo. even many of regionalist schools across the globe used tools of modern architecture to battle against, say, bones and skeleton architecture of mies. kaunas, here, uses traditional architecture to express modernity and modernism. the contradiction leads towards second aspect of heritage sustainability. hence kaunas is barely is a testimony of great processes of momo and thus cannot claim for being one of the best momo, as it is, examples of the world, it (kaunas modernism) applies for being one of a starting point of our reversal coil. hence, slow-paced change, which is unique in terms of particular zeitgeist cannot be announced as progressive neither in terms of architecture, not in terms of lifestyle, now could be example of what needs to be preserved (in the broader terms steaming up from low-scale urbanism in city centers up to the lifestyles, cultural locality and sofort) in order to achieve sustainability for present and future generations of kaunas and lithuania. hence, the continuity that was featured by kaunas modernism instead of rapid revolutionary change has to be following in terms to complete the loop of reversal coil. nowadays cities tend to mimic and copy each other in many ways. starting up with museums that are working as contemporary cathedrals thus catalyzing cultural processes and therefore enhance economical livability of mostly inner city areas. as well as they are preaching for international enterprises to invest and thus creating infrastructure of high-risers. traditional or say authorized discourse of heritage rather enforces these processes of unification as we have discusses the issue via approach of consumerist nature of history and heritage since the enlightenment. this off course refers to perverseness of what auge (2009) calls a ‘non-place’. pervasiveness here is to be found in terms of both functional aspect of architecture where we can draw attention towards unification of new business center areas worldwide as well as geographical expansion of no -places. both variations of expansion of a no place is caused by globalization which is no longer connects to aspects of locality. at the kaunas modernism case, many processes that made up phenomenon of heritage sustainability in particular place have happened by accident. even nowadays, prevention of high-risers in kaunas is more conditioned by economical impossibilities rather being rational choice to preserve modernistic urban fabric. anyway, the idea is to exploit things which were once lagging behind but after one or more temporal periods have passed it (lagging) turns to be a splash of progressiveness of thought transposed to future by explicit manner. in order to preserve kaunas modernism as traditional heritage concept expressed by riceour, one needs conserve the message that property transmits rather than making conservation just only of visual aspects. thus the physical alteration is possible but only in order when heritage presents leads to alteration and impacts it in order to expand and help tacit message to be translated into implicit knowledge. increasing energetic effectiveness and reducing co2 emission is not the aim itself, but it is rather a consequence of continuity of active heritage presence in particular place. heritage narrative in terms of holistic sustainability is difficult to achieve in both drawing scholar methodology and applying it on practice of place management. however, the past here is to be great agent but only when the future is jet decided. this means that reversal coil first dives to the past before it leaps for the future. the possession of history therefore is a negative aspect of placing heritage to work for active agency as it still consumed for simulating things and processes that are actually dead. phenomenon of the flat earth extends the issue towards heritage inability to affect surroundings and also maintains blanked transparency of heritage. conclusions 81 journal of sustainable architecture and civil engineering 2015/4/13 sustainability as well as heritage experiences lots of negation position, when negative impacts are not resolved but only trials of quantitative reduction is to be noticed. heritage livability and holistic sustainability occurs when positive aspects of the past are put on conservancy and then put on work to affect environment in positive manner. the idea relies on interpretative description that is only possible when heritage property is fully transparent that means cognitive dimension is to be as important as visual. only cognition is able to root up splashes of tacit message that is crucial for finding out what must be put on conservancy. kaunas modernism architecture is a decent example explaining how once off-streamed, lower class urban development can transmit a message of sustainability. slow-paced everyday revolution draws a pattern for future development. not to forget, the continuity, at the case of kaunas, is important in both pure aspect of heritage when continuity makes it to be value as contradiction for momo context as well as sustainability requires that continuity, once performed during the interwar, yet to be respected by its extension. finally, the autarchy in terms of cultural interpretation and valuation of the past is crucial to achieve sustainability. in the broader context cultural and natural ecology suffers waste, pollution and various kinds of conflicts across the globe mostly because of economy races. big metropolitan areas and greatest financial centers exploit other areas in many ways in order these ‘other’ developing and so called 3rd world countries seek for exactly the same result that is now performed in the big centers. ignorance for local tradition, heritage and implicit knowledge contained in locality must be the reason of sustainability struggle. ashworth g. 2011. preservation, conservation and heritage: approaches to the past in the present through the built environment. in: asian anthropology. chinese university press, pp. 1-18. http:// dx.doi.org/10.1080/1683478x.2011.10552601 auge m. 2009. non-places: an introduction to supermodernity. verso. barndt k. 2010. layers of time: industrial ruins and exhibitionary temporalities. in pmla, vol. 125, iss. 1. pp. 1-15. http://dx.doi.org/10.1632/ pmla.2010.125.1.134 baron h. 1955. the crisis of the early italian renaissance: civic humanism and republican libertyin an age of classicism and tyranny. princeton university press. barthel-buchier d. 2013. cultural heritage and the challenge of sustainability. left coast press. florida r. 2004. cities and the creative class. routledge. fromm e. 1990. turėti ar būti? vilnius mintis. hansen j., hillier b. 1984. the social logic of space. cambridge university press. harrison r. 2012. heritage: critical appraoches. routlege. james p. 2015. urban sustainability in theory and practise. circles of sustainability. routledge. smith l. 2006. the uses of heritage. routledge. jonutytė j. 2010. kartotė: tradicijos sąvokos matas ir pamatas. in: tautosakos darbai xxxix, pp. 36-49. koselleck r. 2004. futures past: on the semantics of historical time. ny. columbia university press. labadi s. 2013. unesco, cultural heritage and outstanding universal value. ny. alta mira press. nescolarde-selva j et al. 2015 mythical systems: mathematic and logical theory. in: international journal of general systems, vol. 44 iss. 1, pp. 76-97, http://dx.doi.org/10.1080/03081079.2014.947977 parker s. 2004. urban theory and the urban experience. encountering the city. london routledge. plaza. b. 2008. on some challenges and condition for the guggenheim museum bilbao to be an effective economic re-activator. in international journal of urban and regional research. vol.32. iss.2. pp. 506-517. http://dx.doi.org/10.1111/j.14682427.2008.00796.x poulios i. 2014. discussing strategy in heritage conservation. in: journal of cultural heritage i would like to acknowlegde my friends from autc.lt as well as proffesors kestutis zaleckis and juratė kamičaitytė – virbašienė from kaunas university of tech for their educational contribution not only to this particular paper but for overall impact to my perception of environment. references acknowledgment journal of sustainable architecture and civil engineering 2015/4/13 82 management and sustainable development, vol. 4 iss. 1 pp. 16 – 34. http://dx.doi.org/10.1108/ jchmsd-10-2012-0048 ricoeur p. 1984. time and narrative. vol.2. the university of chicago press. ricoeur p. 1985. time and narrative. vol.3. the universtity of chicago press. rodwell d. 2007. conservation and sustainability of historic cities. blackwell publishing. http://dx.doi. org/10.1002/9780470759547 unesco world heritage comittee. 2005. vienna memorandum on world heritage and contemporary architecture – managing the historic urban landscape. otero-pailos, jorge; west, susie. 2010. heritage values. eds susie west. manchester university press. manchester. the bura charter. 1999. the australia icomos charter for places and cultural significance. bura. the paris declaration on heritage as a driver of development. 2011. paris. weireb f. 1986. roots of the bible. merlin books. vienna memorandum. 2005. world heritage and contemporary architecture – managing the historic urban landsape. vienna. wijesuriya g. 2005. the past is in the present: perspectives in caring for buddhist heritage sites in sri lanka. in stovel, h., stanley-price, n. and killick, r. (eds), conservation of living religious heritage: papers from the iccrom 2003 forum on living religious heritage: conserving the sacred, iccrom, rome, pp. 31-43. kastytis rudokas phd student kaunas university of techology, institute of construction and architecture main research area narrativity of urban heritage address tunelio st. 60, lt-44405 kaunas, lithuania phone: +37066362841 e-mail: kastytis.rudokas@ktu.lt about the author journal of sustainable architecture and civil engineering 2016/2/15 66 *corresponding author: josemanuel.gomez@upc.edu total replacement of recycled aggregate and treated wastewater: concrete recycling in extremis http://dx.doi.org/10.5755/j01.sace.15.2.15464 ramírez-tenjhay mayanin gisela, vázquez-gonzález alba beatriz universidad nacional autónoma de méxico, facultad de ingeniería, división de ingeniaría civil y geomática, circuito exterior s/n col. ciudad universitaria c.p. 04510 del. coyoacán méxico d.f. gómez-soberón josé manuel* universidad politécnica de cataluña, escuela politécnica superior de edificación de barcelona, av. doctor marañón, 44-50, 08028, barcelona, spain cabrera-covarrubias francisca guadalupe universidad politécnica de cataluña, escuela técnica superior de ingenieros de caminos, canales y puertos de barcelona, calle jordi girona, 1-3 edificio c 2, 08034 barcelona, spain received 2016/07/07 accepted after revision 2016/09/20 journal of sustainable architecture and civil engineering vol. 2 / no. 15 / 2016 pp. 66-75 doi 10.5755/j01.sace.15.2.15464 © kaunas university of technology total replacement of recycled aggregate and treated wastewater: concrete recycling in extremis jsace 2/15 introduction million tons of construction and demolition waste (cdw) are generated every year around the world, and most of them are not adequately disposed, generating significant pollution on water, soil and air. additionally, the use of freshwater in industrial processes, such as the production of cement, concrete manufacturing and curing for newly-built structures; has damaged the health of our freshwater ecosystems, reducing their volume and hindering their natural cycle of renovation. therefore, the incorporation of recycled aggregate (ra) and treated wastewater (tw) as substitutes for the usual aggregates (ua) and freshwater, could generate significant environmental benefits. in this research, a comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement percentage of ua for ra, is presented; and as an innovation the use tw. the results show that, regardless of the replacement percentage and use of treated wastewater, a concrete with ra and tw (recycled concrete in extremis, crie) had a satisfactory and acceptable or equivalent performance, not differing significantly from the performance of conventional concrete (cc), confirming that the use of ra for concrete building is feasible. keywords: recycled aggregates, recycled concrete, sustainable materials, treated wastewater. concrete is the second most consumed material by man after water, it is estimated that the global annual average production of concrete is about one ton for every human being (world business council for sustainable develop 2009); therefore, the use of ua (main component of concrete) is increased along with cement production and use of concrete (marie and quiasrawi 2012). on the other hand, millions of tons of cdw are generated (construction processes, demolition and restoration works in structures and buildings) (suarez et al. 2006); as an example, only in europe, united states and japan, more than 900 million tons are generated each year (world business council for sustainable develop 2009). because of that, it is important to search for new more-suitable alternatives for the environment, being the use of the ra of cdw, one of the most feasible, reducing the consumption of ua in the production of cement and concrete. 67 journal of sustainable architecture and civil engineering 2016/2/15 the most ancient use of ra is on ancient rome empire roads, and afterwards, generally in europe, at the end of world war ii (shing chai ngo 2004), from which, diverse documented researches have been reported promising results obtained with its use. in japan, with more than a quarter century in the investigation of possible applications, there are achievements of its use, mainly as sub-base material in road construction (up to 96% of ra, in 2000) (rao et al. 2007). however, although it has been demonstrated that the use of ra contributes to reducing the cdw and the use of the ua, these are considered as a low-quality materials, as their virgin properties (mechanical, physical and chemical) can be affected (marinkovic et al. 2010). additionally, the use of fresh water on the industry has caused an excessive extraction of groundwater sources, inducing to an excessive demand of surface water, and on the other hand, at the international level, an emerging critical environmental problem due to the lack of availability of new sources of supply (van den heede and de belie 2012). there are previous investigations that address the search for new alternative sources of water supply for the production of concrete such as: water polluted with minerals, salts and other contaminants as those from streams, lakes and the sea (mccarthy 2008). these studies are focused on analyzing the effects presented in fresh and hardened concrete behavior, concluding that the results are not always satisfactory, since in some circumstances the concrete compressive strength decreases. another alternative that has been explored (common practice in germany) is the use of wash water from concrete, which is composed mostly of mixing water, cement and fine aggregate remnants, obtaining in general adequate results, and a similar behavior with regard to setting time, compressive strength, alkalinity and the chloride content, have been established (silva and naik 2010). finally, there are not many studies about the use of tw in the concrete production, so there are still unknown aspects to consider in terms of reaction that they might have on the concrete, due to the possible presence of contaminants. therefore, the use of ra and tw in the production of concrete has significant potential to solve the problem that represents the final disposal of the cdw, the preservation of natural resources and the potential damages to the environment. the use of ra from the cdw leads to a sustainable practice in the construction industry, as well as the consumption of alternative sources of water supply such as tw; so the main goal of this research is to establish the feasibility of using ra and tw for the manufacture of a new recycled concrete, calling it crie, which potentially have the ability to face obstacles precluding the use of ra, strengthen and improve the legislation to develop recycled materials, and provide users reliability to use them. the construction materials employed in the experimental process were portland composite cement (cpc) type ii 30r rs classified in accordance with nmx c414 onncce 2004 (anon n.d.) and astm c-595 (astm standard c595/c595m 2016) standards. the ua were acquired to a local quarry, whereas the ra were obtained from “concretos reciclados”, factory in méxico city (19°19’12.3”n 99°03’16.2”w) which processes aggregates from cdw (ramos guevara 2007). the recycled coarse aggregate (rca) used was produced from concrete waste graded in accordance with astm c 33 standard astm (standard c33/c33m 2016), while the recycled fine aggregate (rfa) came from the fine remnants of the rca crushing process. it has been established that the quality of aggregates partially determines the characteristics of the concrete that contains them (in particular its strength and durability) (paul 2011), standing out as most important some physical characteristics; its density, bulk density, water absorption, porosity, particle size distribution (including its texture and shape). the physical characterization obtained for the ua and ra used in this research are presented in table 1, along with the standards under which the tests methods were carried out. materials journal of sustainable architecture and civil engineering 2016/2/15 68 the d of ua used are within the normal range (2.4 to 2.9 g/cm3) (kosmatka et al. 2004); while the ra values referenced in the literature indicate that they decrease up to 10% compared to the ua (marie and quiasrawi 2012) (marinkovic et al. 2010). therefore, both aggregates used in this research have been considered suitable and appropriate. it is worth mentioning that the usual coarse aggregates (uca) are 0.06 g/cm3 heavier than the rca, being the fine fractions those with the most significant differences (0.2 g/cm3). a high wa does not necessarily make the aggregates unsuitable; however, this could become in certain circumstances, an indicator of inadequate performance for concrete properties. as it is observed, the wa for both ra is greater than ua (6.03 and 14.38% in rca and rfa, respectively). if ra fractions are compared, the rfa fraction exceeds 7.1% of rca; these particular variations in the wa of ra is known and widely accepted to be attributed to old mortar adhered to the aggregate particles (malešev et al. 2010; thomas et al. 2016; descarrega 2011; de brito and robles 2010; silva et al. 2014; marie and quiasrawi 2012; rao et al. 2007; marinkovic et al. 2010; paul 2011) (more porous), which concentrates on the rfa fraction by the effect of crushing process in the aggregates (mortar weaker than ua). the bd represents the weight and space occupied by the aggregates, pores and gaps found between the particles, this property affects the demand for cement and influences the required proportion of coarse aggregate (ca) in the mix design (kosmatka et al. 2004). the difference of bd between the rca and uca studied can be attributed to particles angularity of the rca (concrete fracturing process and subsequent trituration), which causes an increase in the amount of gaps (poor particle arrangement), while uca has a less aggressive production and because of its origin it has more rounded particles allowing a better particle arrangement. however, in despite of the previous differences and their implications, both aggregates are classified as suitable for a structural normal weight concrete (kosmatka et al. 2004). the fm describes fine aggregate (fa) particle size and thickness (bigger particles tend to have a higher fm), it sets the minimum amount of fa needed to fill the gaps between the ca, thus improving the workability of concrete (“lubricant” function for ca). the rfa of this investigation reached a fm above us standards (2.3 3.1) (astm standard c33/c33m 2016), when compared to a usual fine aggregate (ufa), rfa has a higher fm; which must be considered to understand and explain the properties of concrete. granulometric profiles for rca, uca, rfa and ufa were tested using the standard specification astm c33 (astm standard c33/c33m 2016) establishing the distribution of their particles sizes, the granulometric curves of the four aggregates used are shown in fig. 1 and fig. 2, along table 1 physical properties of aggregates property/classification astm rca uca rfa ufa density (d) [g/m3] c127 2.23 2.29 ----water absorption (wa) [%] 10.48 4.45 density (d) [g/m3] c128 ----2.11 2.31 water absorption (wa) [%] 17.58 3.20 bulk density (bd) [kg/m3] c29 1254.99 1376.21 ----fineness modulus (fm) c33 ----4.00 2.50 nominal maximum size (nms) [mm] c33 25.00 25.00 ----69 journal of sustainable architecture and civil engineering 2016/2/15 with the standard limits. the ca (recycled and usual) meet the recommended particle distribution limits; while fa denoted that both recycled and usual are outside the standard limits (the ufa slightly above the upper limit and rfa far below the lower limit); so to obtain a suitable particle size, the rfa should be corrected or compensated by blending particles of different sizes. notwithstanding the above, no changes have been established in any of the granulometric profiles of aggregates, assuming that the most common granulometric profiles are never perfect (naturally), and that this is a more common option for manufacturing an in-situ concrete and more practical for industry. fresh water used in concrete mixtures was obtained from water supply facilities of the national autonomous university of méxico (19°19’54.156” n, 99°11’5.647” w), satisfying the mexican standards in accordance with the nom-127-ssa (nom-127-ssa1-1994 2010) that establishes permissible limits for fresh water quality, fig. 1 coarse aggregates granulometric curve fig. 2 fine aggregates granulometric curve changes have been established in any of the granulometric profiles of aggregates, assuming that the most common granulometric profiles are never perfect (naturally), and that this is a more common option for manufacturing an in-situ concrete and more practical for industry. fig. 1. coarse aggregates granulometric curve fig. 2. fine aggregates granulometric curve fresh water used in concrete mixtures was obtained from water supply facilities of the national autonomous university of méxico (19°19'54.156" n, 99°11'5.647" w), satisfying the mexican standards in accordance with the nom-127-ssa (nom-127-ssa1-1994 2010) that establishes permissible limits for fresh water quality, whereas the treated wastewater was obtained from the wastewater treatment plant "cerro de la estrella" (wtp-ce) located in méxico city (19°20'12.2"n changes have been established in any of the granulometric profiles of aggregates, assuming that the most common granulometric profiles are never perfect (naturally), and that this is a more common option for manufacturing an in-situ concrete and more practical for industry. fig. 1. coarse aggregates granulometric curve fig. 2. fine aggregates granulometric curve fresh water used in concrete mixtures was obtained from water supply facilities of the national autonomous university of méxico (19°19'54.156" n, 99°11'5.647" w), satisfying the mexican standards in accordance with the nom-127-ssa (nom-127-ssa1-1994 2010) that establishes permissible limits for fresh water quality, whereas the treated wastewater was obtained from the wastewater treatment plant "cerro de la estrella" (wtp-ce) located in méxico city (19°20'12.2"n whereas the treated wastewater was obtained from the wastewater treatment plant “cerro de la estrella” (wtp-ce) located in méxico city (19°20’12.2”n 99°04’34.0”w), which meets the mexican quality parameters corresponding to the maximum permissible contaminants for treated wastewater to be used in public services with direct human contact nom-003-semarnat (nom-003semarnat-1997 2003). to assess the possibility of using water from the wtp-ce as an alternative source for mixing water in concrete, some tests were conducted (see table 2). the results are compared with the maximum limits set by astm c 94 (astm standard c94/c94m 2016) and nmx-c-122-2004 (nmxc-122-onncce-2004 2004) (north american and mexican standards, respectively); in both cases, all the required parameters are met except the content of fats and oils. the content of fats and oils can affect the development of concrete strength; it has been recommended that the content of mineral oil will not exceed 2.5% in cement weight (kosmatka et al. 2004). therefore, it has been considered that water of the wtp-ce will not cause significant effect on the strength of concrete (at least for its particular effect). journal of sustainable architecture and civil engineering 2016/2/15 70 several investigations (kou 2006; moriconi n.d.; marie and quiasrawi 2012; shing chai ngo 2004; malešev et al. 2010) have shown that concrete from mixes containing up to 30% of rca have lower mechanical properties than concrete with ua, on the another hand, it is also known that compressive strength for cc is directly correlated to water-cement ratio (w/c); therefore in this investigation both criteria were considered as design parameters in the mixtures studied. to ensure workability (without use of additives) the slump range of fresh concrete selected was 80-100 mm and in order to achieve a concrete strength of 25 mp (structural concrete) a w/c ratio of 0.62 was used for all mixtures. three types of mixtures were defined to verify the feasibility of replacing uca with rca; a control concrete mixture (100% ua) and two with rca (25% and 30% replacement of uca with rca. additionally, to evaluate the feasibility of using a crie, the control concrete mixture was done using tw and two mixtures were done using 100% of rca and rfa (one with fresh water and the other one with tw). the concrete mix design was done using absolute volume method considering the properties obtained in the characterization of the ua and ra (kosmatka et al. 2004); in which the masses proportions are determined assuming the aggregates are in saturated surface dry condition (ssd), then these are corrected by absorption and the moisture content of the aggregates. concrete mix design in ssd is shown in table 3. the incorporation sequence of materials into the mixer could have a significant effect on the uniformity of concrete (astm standard c94/c94m 2016), so the method used for the mixture process was following astm c 192 (astm standard c192/c 192m 2016). fresh concrete properties were determined in accordance with established standards: slump (s), air content (ar) and unit weight (uw), according to the astm c 143(astm standard c143/c 143m 2015), astm c 231 (astm standard c 231 2014) and astm c 138(astm standard c138/c138m 2016), respectively. cylindrical specimens of 150 mm x 300 mm were made for mechanical test, the conditions for making and curing the specimens were carried out in accordance with astm c192 (astm standard c192/c 192m 2016). compressive strength testing was performed according to astm c39 table 2 quality parameters of treated wastewater parameters/standards astm c 94 ppm nmx-c-122 ppm water from wtp-ce chlorides as cl: _ prestressed concrete on in bridge decks (maximum) _ other reinforced concrete in moist environment or contact with metals (maximum) 1.17500 600 1000 1000 sulfate as so4 3000 3500 70 alkalies as na+ 600 450 97 total alkalies as na+ 600 450 97 carbonates as co3 --600 140 ph (h+) --≥ 6.5 7.52 organic material --150 22 suspended solids in natural water --2000 6 suspended solids in recycled wastewater * --35000 6 fats and oils --0 0.056 * wash water used for washing and cleaning mixer trucks, concrete pumps and other equipment is considered as recycled water. methodology 71 journal of sustainable architecture and civil engineering 2016/2/15 (astm standard c39/c 39m 2016) using satec sf-1u universal tensile and compressive tester, using neoprene pads in both ends of the specimens (astm c1231 (astm standard c1231/c 1231m 2015)); repetitiveness per variable was two specimens, at 14 and 28 days. in addition, an analysis of scanning electron microscopy (sem) was performed in two specimens of concrete (c and crie), in order to clarify the behavior of hardened concrete, the technique was performed with the microscope joel (jsm-651), taking and then conditioning a representative fraction of each specimen. aggregates mix with content of rca mix with content of tw c r25 r30 c* cw crie rf=0 rf=25 rf=30 rf=100 rf=0 rf=100 uca 963 703 665 --963 --rca --237 281 816 --816 ufa 687 667 661 --687 --rfa ------723 --723 c = control, rf= replacement factor, r25 and r30 = mix containing 25% and 30% of ra, c*= total replacement with rca and rfa, cw= control mix with tw, and crie= c* mix with tw. table 3 mix design in ssd results and discussion table 4 testing results of fresh concrete properties mix with content of rca mix with content of tw c r25 r30 c* cw crie rf=0 rf=25 rf=30 rf=100 rf=0 rf=100 ar [%] 2.4 2.4 2.6 2.7 2.5 2.8 s [mm] 95 90 90 80 90 85 uw [kg/m3] 2132 2109 2115 2046 2144 2075 the results for fresh concrete testing are showed in table 4. the ar for a cc is in a range from 2% to 3% (kosmatka et al. 2004) (concretes without air entraining admixtures); in this research, the ar for the mixes is between 2.4% and 2.8%, so all mixtures are in the usual ar range without significant differences between them. therefore, the effect of using rca, rfa or tw-together or separately, regarding this property, does not affect the mixtures studied. it has been established that the ar is directly correlated to the s (kosmatka et al. 2004); likewise, the values obtained are within the range considered in the mix design (80 to 100 mm). however as operating experience of its use, c* and crie mixtures had poor workability and rough texture due to a high content of thick particles and greater wa of rfa; resulting in mixtures with low natural compaction and difficult to place in practice. the highest uw corresponds to the mixture cw, followed by c (with minimum difference), and the lowest belongs to c*; summarizing, the variation between all the samples studied only reached 4.5%, consistent with previous studies (malešev et al. 2010). the average results of the compressive strength of the specimens appear in fig. 3, where two aspects of common behavior can be perceived: in the first, the results obtained at 14 days always manage to reach 86% of the design strength (kosmatka et al. 2004); and second, the design strength is met; 25mpa (except crie). journal of sustainable architecture and civil engineering 2016/2/15 72 fig. 3 concrete strength fig. 4 sem image with x500 zoom: a) usual concrete, b) concrete crie analyzing the results of the specimens with different rf, a correlation was found between the rf and strength loss; 2% and 3% (r25 and r30 respectively with respect to c) at age of 28 days. in the other hand, comparing specimens cw with respect to c, strength loss is 5.2% (both ages of study); and the difference between c* with crie (where also the only variable factor is tw), the compressive strength decreases by 3.5% and 1.2% for the 14 and 28 days, respectively. finally, concerning the proposal for rf = 100%, were the first variable factor are rca and rfa (c*) the strength loss with respect to c is 10.4% and 6.8% at 14 and 28 days, respectively. as a hypothesis for the above behavior, in addition to adverse effects due to the physical properties of the ra (low d, high porosity), on the concrete mechanical behavior; it is suggested that the high porosity, the old adhered mortar on the original aggregates (higher concentration in the fine fraction of the aggregate), and the creation of new weaker areas around the aggregates called interfacial transition zone (itz) which is formed between a recycled aggregate (with adhered mortar) and the new concrete mortar; are the causes of strength loss. in order to validate this, images (sem) were performed; seeing that in concrete with ra replacement these areas are wider with a noticeable increase present in the matrix (see fig. 4). finally, because of the tw chemical studies and the minimum variations of strength between crie and a cc, it is concluded that the possibility of using this type of water in the creation sustainable concrete is feasible, practical and appropriate; thereby mitigating the demand of fresh water in the industrial manufacturing of concrete, besides contributing to the rational use of nonrenewable resources. new mortar usual aggregate itz a) new mortar recycled aggregate itz b) new mortar usual aggregate itz a) new mortar recycled aggregate itz b) ba 73 journal of sustainable architecture and civil engineering 2016/2/15 based on the research conducted, there is evidence of the feasibility to use (limited in some aspects of resistance and durability) the rca and the tw as components of recycled concrete; considering this as a truth, the possible applications of recycled concrete may not be 100% comparable to the cc, but the rational use of materials in the constructive elements of low requirements makes possible its application. the above, allows to give solution to cdw and the tw, promoting the sustainability and the use of recycled materials in construction. from the results of this research (tests on concrete fresh and compressive strength), it was observed that all mixtures of concrete containing the tw presented generally favorable values according to the regulations for concrete (even that the tw does not satisfy the limits of contents of oils and fats), therefore its use could be a viable alternative to reduce the consumption of fresh water through the use of tw. the tw of this study, can be considered as a source of water acceptable for the manufacturing of concrete; however, it is mandatory to carry out all previous analysis necessary that allow to guarantee the fulfillment of the regulation tolerances to ensure it as a constituent element of a concrete. in cases where these requirements are not achieved, it will be necessary to conduct a study of the possible affectation of the contaminant in the concrete, entailing that to use them, most pollutant substances that can cause deterioration in the strength and durability, must be removed. so the tw will have to be submitted to a constant control in wastewater treatment plants. the rca used are of high quality and no significant differences were present compared with ua, so it is possible to obtain a concrete with a satisfactory mechanical behavior, comparable with a cc. moreover, the rfa has characteristics of poor quality so that it is unfeasible for structural use, however can be used in non-structural concrete elements. the d and bd of rca are not significantly lower, so that it meets the pre-established recommendations. in addition, workability, ar and s do not show substantial effects in any of the treatments where rca was used. in the mixture crie one centimeter less of slump was obtained with respect to the control mixture, so its value is insignificant and requires no correction for practical implementation. finally, the wa of the rca is greater with respect to a uca, however, this does not affect the characteristics of the concrete. this increase of the wa in the rca, can be decisive for the behavior of durability of the concrete recycled to its resistance to the freeze-thaw (cold climates); for which, will be necessary the accomplishment of future research that demonstrate this possible affectation to the durability (process of micro-cracking, number of freeze-thaw cycles tolerable, additions of improvement of the concrete, palliative concreting processes, etc.). finally, there is a clear need to expand this research; since more tests and series of different types and origins of the rca and tw might generate a wide statistics that give strength and solidity to constructive, practical, and safe applications. the previous comment is based on the origin of the rca and tw materials, with contents of very variable, complex and slightly usual pollutants in the composition of the concretes. future studies, which established the tolerances of each pollutant in the different aspects of the strength and durability of concrete (separately or combined), as well as the search of criteria for the establishment of applications with low solicitations, will mark the future, acceptance and inclusion in the regulations of these new sustainable concrete. for the case of the tw, contents of substances organic, acidifying and reactive with the chemistry of the cement; as well as for the rca, its origin (type of concrete which comes), process of crushing and shape of particles, are considered to be important variables to study in future research, to obtain a broader understanding of the concrete that include them. conclusions the authors express thanks to: research project s-01117 from ctt-upc, to epseb-upc, to the department caii-epseb, to depfi-unam and to the scholarships program for master degree studies by conacyt. acknowledgment journal of sustainable architecture and civil engineering 2016/2/15 74 nmx c-414-onnce. industria de la construcción-cementos hidráulicos-especificaciones y métodos de prueba, organismo nacional de normalización y certificación de la construcción y edificación, s.c., diario oficial de la federación, méxico, d. f., 2004. astm c231/c231m-14. standard test method for air content of freshly mixed concrete by the pressure method, astm international, west conshohocken, pa. 2014. doi: 10.1520/c0231_c0231m-14 http://dx.doi.org/10.1520/c0231_c0231m-14 astm c1231/c1231m-15. standard practice for use of unbonded caps in determination of compressive strength of hardened cylinders concrete specimens, astm international, west conshohocken, pa. 2015. doi: 10.1520/c1231_c1231m-15 astm c138/c138m. standard test method for density (unit weight), yield, and air content (gravimetric), astm international, west conshohocken, pa. 2016. doi: 10.1520/c0138_c0138m-16 http://dx.doi.org/10.1520/c0138_c0138m-16 astm standard c143/c143m. test method for slump of hydraulic-cement concrete, west conshohocken, pa. 2015. astm c192/c192m. standard practice for making and curing concrete test specimens in the laboratory, astm international, west conshohocken, pa. 2016. doi: 10.1520/c0192_c0192m-16a http://dx.doi.org/10.1520/c0192_c0192m-16a astm c33/c33m-16. standard specification for concrete aggregates, astm international, west conshohocken, pa. 2016. doi: 10.1520/c0033_c0033m-16 http://dx.doi.org/10.1520/c0033_c0033m-16 astm c39/c39m-16b. standard test method for compressive strength of cylindrical concrete specimens, astm international, west conshohocken, pa. 2016. doi: 10.1520/c0039_c0039m-16b http://dx.doi.org/10.1520/c0039_c0039m-16b astm c595/c595m-16. standard specification for blended hydraulic cements, astm international, west conshohocken, pa. 2016. doi: 10.1520/c0595_c0595m-16 http://dx.doi.org/10.1520/c0595_c0595m-16 astm c94/c94m-16a. standard specification for ready-mixed, astm international, west conshohocken, pa. 2016. doi: 10.1520/c0094_c0094m-16a http://dx.doi.org/10.1520/c0094_c0094m-16a de brito j., robles r. recycled aggregate concrete (rac) methodology for estimating its long-term properties. indian journal of engineering and materials sciences, 2010; 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(2016, june) the cement sustainability iniciative. [online]. available: http://www.cement.ca/images/ stories/recyclingconcrete_summary_csi.pdf mayanin gisela ramíreztenjhay msc student national autonomous university of mexico, faculty of engineering, civil and geomatic engineering division main research area recycled concrete, sustainable construction address circuito exterior s/n col. ciudad universitaria c.p. 04510 del. coyoacán méxico d.f. tel. +52 5622 8001 e-mail: mayanin. tenjhay@outlook.com alba beatriz vázquezgonzález full time professor national autonomous university of mexico, faculty of engineering, civil and geomatic engineering division main research area recycled concrete, sustainable construction address circuito exterior s/n col. ciudad universitaria c.p. 04510 del. coyoacán méxico d.f. tel. +52 5622 8001 e-mail: mayanin. tenjhay@outlook.com josé manuel gómez soberón full time professor polytechnic university of cataluña, school of building construction of barcelona, department of building architectural ii main research area concrete recycled, porous structure of concrete, sustainable construction, minimization, reuse and recycling in construction, ict in teaching, virtual campus teachers address doctor marañón, 44-50, 08028, barcelona, spain tel. +34 93 401 6242 e-mail: josemanuel. gomez@upc.edu francisca guadalupe cabreracovarrubias phd student polytechnic university of cataluña, barcelona school of civil engineering main research area recycled concrete, sustainable construction address calle jordi girona, 1-3 edificio c 2, 08034 barcelona, spain tel. +34 93 401 6900 e-mail: guadalupe. cabrera04@gmail.com about the authors journal of sustainable architecture and civil engineering 2016/4/17 68 *corresponding author: jurate.mockiene@ktu.lt study of consequent damage of metal pivotal structure on maintenance in polluted surroundings http://dx.doi.org/10.5755/j01.sace.16.7.16080 jūratė mockienė*, valerijus keras, gintaris cinelis department of building structures, kaunas university of technology studentu str.48, lt51367 kaunas, lithuania received 2016/08/18 accepted after revision 2016/11/07 journal of sustainable architecture and civil engineering vol. 4 / no. 17 / 2016 pp. 68-76 doi 10.5755/j01.sace.17.4.16080 © kaunas university of technology study of consequent damage of metal pivotal structure on maintenance in polluted surroundings jsace 4/17 rudiments of author’s position the paper is related with tends to elucidate various forms of harm generated by space pollution to economy of the region in context of the ideas of agenda 2000 etc. the study discusses the data of the air pollution and subsequences of damages that are fixed in elements of high-rise metal structures. it adduces some data of factual pollution that is dangerous to high-rise metal structures, location of initial generators of pollutants, interrelations of polluted flows during their migration in the air. experimental observation reveals the accumulation of micro and local defects, and their joining process. afterwards aftereffects are discussed as stress concentration around defects, wear and tear of structures, the scattering of strength resources, loss of the durability of single element and the structure in whole. the residual strength of steel elements of structure was tested using standard specimens that had been cut out from the elements of structure at the end of its exploitation. keywords: air pollution, harm, monitoring, concentration, corrosion, supports, impact, assessment. the main goal of this paper is to reveal a level of environment pollution around specific structures exploited in the open air concomitant processes and after-effects characteristic to their exploitation. rudiments and basic point of this study are: 1 consolidation and special analysis of information accumulated over a long time on natural concentration of aggressive pollutants in the environment affecting the objects in the unfavourable environment. 2 experimental research of standard mechanical characteristics specific to structural mate-rial after structure exploitation (residual strength, etc.) 3 computer-based imitation modelling of primary destruction process and discussion of its possible consequences. the object of the study is complex as it includes pollution data in the aggressive environment enveloping characteristic building structures and its destructive impact on endurance of these structures. for instance, peculiar high-altitude clouds and their influence on the destruction of various structures such as masts, towers, supports of electro power lines, etc. is presented in the article. data about specific pollution and aggressive environment around the objects in high volume traffic 69 journal of sustainable architecture and civil engineering 2016/4/17 routes and traffic jams, their destructive influence and possible concomitant effects occurring in the construction of bridges and viaducts are revealed simultaneously. relevance of this study lies in today’s regulations. underestimation of the above-mentioned modern aggressive factor as it becomes incompatible with a current tendency to expand sustainable development (separately a resource saving construction) is clarified. its significance is determined by a demand for systematic accumulation of versatile factual information about the extent of natural losses in this complicated situation. practical engineering needs also stimulate the tendency towards complexity. a serious concern and the abundance of scattered efforts for primary elucidation and quantitative evaluation of water, air, soil, food, flora, and fauna pollution are observed. unfortunately, the collected data is dispersed in various resources and is vaguely associated with social, economic and especially engineering losses. this is an obvious obstacle to achieve desirable practical goals. this deficiency has to be gradually filled up. this article is expected to serve as aspiration to reach one of the sub-goals from a wide set of goals in sustainable development. a serious concern is continuously declared and numerous efforts are undertaken in order to properly reveal and estimate the extent of water, air, soil, residence, food, flora, and fauna pollution, etc. quantitatively. nevertheless, all the data collected is scattered and not related properly at time with problem of structure endurance. thus, the data has limited value or is insufficient for modern engineering theory and practice development intended to vital resources and material resources saving. this drawback is sensible to be gradually filled up by systematization of store knowledge and supplementary information. taken alone, building sphere and corresponding losses generated by environment pollution are to be discussed. accidents in structures and related objects have caused structure damage or totally destroyed them at last. this phenomenon has been continuously observed in various regions of the world. the above mentioned accidents occur in various structures of steel, reinforced concrete, wood and other materials. consequently, discrepancy between environment pollution and endurance of building structures is a relevant problem in contemporary world and has to be considered in versatile perspective. contemporary fore going stimulators (predecessors) stimulating construction discretization can be revealed as various forms of air pollution causing construction environment aggression in nature exploitation. it is relevant and sensible to note that a certain group of structures is exploited in the open air without a special protection. various acidic pollutants can be likewise hazardous to steel constructions and equipment. bearing structures of bridges, various technological equipment, towers, masts, supports of power lines, etc. are among them. their working life, fatigue and cracking have not been sufficiently studied. open air is undoubtedly polluted environment suitable to hasten corrosion in steel, concrete or wood. this is particularly noticeable for hardened steel. unfortunately, a significant complex of data characteristic to the specific corrosion process and ensuring a sufficient description of kinetic of various sub-processes is absent now. this lack of information is a serious obstacle to achieve optimal design, to assure preventive measures in exploitation, i.e. safe and economically rational preventive method against deterioration and cracking, also for other effective solutions. consequently, this obstacle is to be gradually eliminated. quite widely are discussed their location into air (paulauskienė et al. 2011 etc), soil (butkus et al. 2004; stravinskienė 2011 etc), rivers and seas (šukytė et al. 2002 etc) etc. excerpt of some quite characteristic to exploitation spell of rather early wrecked structures data are presented in tables 1,2,3. journal of sustainable architecture and civil engineering 2016/4/17 70 table 1 excerpt a concentration of sulphur pollution in south lithuania (šopauskienė, jasinevičienė 2004) years average annual extremes 1981 7.8 3.6 ... 14.2 1982 8.3 3.8 ... 25.4 1983 9.3 3.4 ... 19.4 1984 8.0 5.7 ... 16.2 table 2 excerpt of data a so2 pollution into south – west lithuanian area (sirakov et al. 1989) table 3 excerpt a concentration of sulphur pollution in south lithuania (šopauskienė, jasinevičienė 2004) žuvintas 4.2 preila 4.1 molėtai 4.3 the european (ex-ussr) part of russia 1.65 – 4.0 southern sweden 3.4 – 4.8 northern sweden 2.0 southern norway 6.9 10 northern norway 0.5 – 0.8 eastern hungary 7.0 west germany 3.9 – 8.0 years so2 (c m kg/m3) so4 (c m kg/m3) 01.82 11.54 13.06 01.83 5.14 5.09 01. 84 16.68 10.55 01. 85 18.54 17.73 02.11.85 9.52 9.3 2there are also other contaminants besides the sulphur compounds that are dangerous to structural steel. sulphur acid is probably the most dangerous material. therefore some part of data about the pollution extent, forms and concentration of sulphur pollution is provided as examples. (measurements fixed during the mast maintenance period (80 – 100 years) and contaminants combinations change comprising big sets of information which are the subject for analysis and discussion in the dedicated literature.) at the time already is some actual data about pollute emissions, revealed in industry (paulauskas, klimas 2005; vyzienė, girgždys 2009), traffic (lippa, špakauskas 2002; byčenkienė, girgždienė 2006; vaitiekūnas, banaitytė 2007), agriculture (butkus et al. 2004), cattle-breeding (kavolėlis, bakutis 2004), forestry (ozolinčius 2005; gimbutaitė, venckus 2008). tendencies and requirements of optimal design promote the increased focus on structure rational viability in polluted environment (agenda and other). this aim could be achieved by complex optimisation. this condition is quite significant if a structure is planned to be exploited under the insufficiently known conditions, e.g. in aggressively polluted environment. these conditions cannot be ignored in searching optimal solutions ensuring rational structure viability in various aspects. the real behaviour of optimised buildings and structures defining their rationality is the function of conditions occurring during structure exploitation (keras et al 2005; kudzys, juocevičius 2005; keras, mockienė 2007,2009). in most cases it is a consequence of complicated events and processes. it directly refers to buildings and structures exploited in polluted environment for a long time, i.e. high-altitude towers and masts installed in the area of chemically aggressive industrial pollutants, nearby industrial zones and directly in them. this information can be significant in solution multipurpose optimisation in designing high-altitude objects. processes of structure corrosion provoked by contaminants 71 journal of sustainable architecture and civil engineering 2016/4/17 abundant data on aggressive pollutants in such zones was described and partially summarised in earlier publications and the fore presented part of the article. a part of this data is compiled by long-term natural observations peculiar for real structure-related events, processes and consequences. the accumulated data shows various details and facts of buildings and structures behaviour. it is appropriate to generalise the information and relate it to the data of viability change and the development of construction damage revealing practical significance and impact of their combinations. it would contribute to solving optimisation issues. some peculiar phases can be recorded in the behaviour of high-altitude steel structures and constructions during their long-term exploitation under aggressive conditions. the major part of steel corrosion factors occurs in the surface layer of a structure element. it includes painting defects or other corrosion-sensitive metal surfaces. deterioration formations are noticeable in metal surface contacting with polluted environment that includes air and humidity. they include dotted corrosive areas, which are microscopic at the start. steel transforms from solid state into powdery condition in such dotted areas. the major part of steel as a material component reacting to moisture, air and pollutants turns into surface micro craters filled by accumulation of powdery corrosion products. the accumulated powder absorbs and stores environment moisture and polluted air, so harmful and aggressive for the metal. these are the favourable conditions for corrosion to develop and deepen the crater. initially, craters were similar to dotted areas. later on they develop into adjacent surface areas. eventually, they form entire surface corrosion. such formations create concentric areas, gullies and grooves of corroded steel. moreover, dotted corrosion formations, craters on the surface cause accompanying effect – closed metal corrosion. it is a process of micro cavities and formations occurring under the metal surface unaffected by surface corrosion. they can form closed gully cavities among dotted corrosion areas and craters. corrosion development under the metal surface layer might be more hazardous from the point of view of metal deterioration. its prevention by coating metal with anti-corrosive layers is ineffective. this process is more complicated and causes significant consequences. it occurs simultaneously as the development of primary deterioration craters. this process evolves while metal surface layer is still intact, it damages metal layer which is not comparatively deep between dotted corrosion areas. products as the consequence of closed under-surface corrosion processes obtain higher volume than the initial volume of non-corroded steel components. thus, development forces occurring and affecting under-surface cavities are high and exceed cohesion forces of material (steel) components. expansion forces tear surface layer area above gully up even if dotted corrosion formations or other damage are not yet formed. such torn surface layer is rough with micro, sub micro concaves, sharpness and protrusions. the new surface area after corrosive tear is much larger than relatively even surface area of a structure element prior to corrosive damage. it means that the new area is expanded regarding steel and polluted environment; it creates favourable conditions for intensive corrosion development. corrosion development gradually changes distribution of surface stresses and strains. dotted deterioration areas, micro damage and other assumptions cause the accompanying effect, i.e. concentration of stresses and deformations. any concentration of stresses and deformations supplement the initial impact of roughness of technological processing and other micro unevenesses of structure element surfaces on surface stress distribution. craters, gullies, cracks and fissures occur in structural steel element under the effect of polluted environment and corrosion; they influence dispersion of steel macro characteristics. defect development starts to significantly impact the local and nominal strength data of steel, its yield, strength and deformation rates. corrosion start and its development are caused by surface processing irregularities or relatively low quality of technological processing, i.e. defects occurring in shrinkage of welding seams as polluted moisture is condensed there. various chemically active steel admixjournal of sustainable architecture and civil engineering 2016/4/17 72 tures also have similar corrosive effect. technical steel is a combination of various admixtures and additives, though their percentage in a general composition is relatively low. high-altitude construction masts usually are made of rolled steel profiles. technological rolling processes leave microscopic cracks on hardened steel element surface in some places. the major changes are possible in the stress-strain state of a structure element as corrosion promoted by polluted environment together with other factors gradually change so-called surface stresses and deformations. in linear stress and deformation distribution occur micro, sub micro and local islands of stress-strain concentration as 3d stress-strain state zones, which reduce element strength reserve and increase deterioration hazard. fig. 1 variation initial forms of corrosive damages fig. 2 an example of following evolution of corrosive damage on surfaces of metal structure into pollutes surroundings. some characteristic samples fig. 3 totally corroded superficial layer of structural element significant deformation unevenness peculiar to stress concentration stimulate material surface layer cracking and cavity occurrence. this is secondary – mechanical – deterioration of structure elements. it is not directly dependent on environment pollution or corrosion. it is an accompanying effect, an indirect consequence of corrosion processes, function of partially changed border conditions. in turn secondary cracking increases steel structure areas for corrosion and creates conditions for development of surface corrosion. this publication presents the practical study result extracts of the main outcome of the analyzed processes. the pictures (fig. 1, 2, 3, 4) provide specific information on steel element damage occurring during various periods of structure exploitation. other illustrations (fig. 5) reflect the data on steel mechanical properties, their change and dispersion after long-term exploitation of the analyzed structures. the first part of the practical study analyzes the most significant visible outcomes of destructive corrosive-erosive processes. accumulated data reveal formation of gullies, their merger into specific forms of damage: local areas, damaged zones, stripes (fig. 1, 2, 3, 4). the pictures provided below reflect specific forms of steel element damage, their arrangement and amounts. pictures (fig.1, 2, 3, 4) present the main part of the mostly occurred long-term steel corrosion examples – local zones (fig. 1), stripes and surface caused by environment pollution (fig. 2), total surface destruction (fig. 3). aggressive environment causes steel to lose primary standard characteristics of a manufacturer. mechanical characteristics of steel were analyzed in order to find out the possible impact of damage to structure viability. standard tests were used to determine steel yield, strength and hardness characteristics. test data are processed to show changes of mechanical properties after exploitation in polluted environment. 73 journal of sustainable architecture and civil engineering 2016/4/17 fig. 4 some characteristic damages and defects fixed during observation of various masts after a long time of their exploitation a part of indexes of mechanical properties are provided in the pictures (fig. 5). histograms provided in presented figures are the extracts from data sets that were gathered by examining in a general standard way the resistance of elements taken from one third of middle part of the mast. this data are the resistance properties which were obtained using tension standard form specimens to their rupture in the press. additionally were brinell hardness tests performed in the environment of these specimens by distracting the imprint from probable specimen rupture place. the mast under investigation has been used in open-air conditions in lithuania near kaunas. the mast structure was built of the cross sectional lattice, the ends of lattice elements were welded to vertical branches (stands) of the mast. besides observations confirmed that corrosion damages not only the mast elements, their weld seams but also the guys that hold the mast, their anchors, guy tension control devices. proper guys tension reduce not only because of pulsating wind or changing temperature effects but also due to slips in the damaged anchors and other factors. fig. 5 dispersion of tested strength (test of standard specimens) (a) and hardness (b) for steel mast structure after its remove out of exploitation a b journal of sustainable architecture and civil engineering 2016/4/17 74 results of the conducted tests revealed that mechanical properties of steel constructions after their exploitation periods changed significantly from the ones from manufacture standards. steel production is certified by manufacturers. production mechanical properties have to meet standard requirements, especially the products, which are used for crucial structures and buildings. requirements for production quality in various countries provide 3% characteristic dispersion, e.g. strength indexes. the given pictures prove that steel macro characteristics on tension and hardness do not meet manufacture standards after exploitation of structure in corrosion-stimulating environment. characteristics dispersion becomes very wide. tests for tension and hardness were cut from structure masts after exploitation period. test data emphasizes a great dispersion of mechanical characteristics. it was 25-35% for steel yield indexes, 28-40% for strength characteristics (fig. 5). dispersion was twice higher for steel hardness characteristics which were determined for the same samples later (fig. 5). such differences reflect uneven arrangement and amount of damage. hardness tests were more localized. thus, hardness indexes are more susceptible to damage influence for mechanical properties of localized metal areas. tension tests evaluate a more generalized (evened) steel cross-section resistance to deformation. authors of the paper were seeking to note that wide researches are necessary in the point of view of sustainable development and sustainable building. they could cover more cases in various countries similarly as it is happening with investigations of the pollution effects to forests, agriculture, health, etc. the research coverage can be defined as mechanical researches of building deterioration, its modelling, forecast, economical estimation, legal regulation, and possibly damage recovery. it would be appropriate to consider the research program of such like direction. conclusions 1 many engineering systems are affected by various aggressive emissions and rather changeable polluted surroundings on the exploitation phase of systems. it causes continuously unsteady reliability and behavior of exploited structure. unlike probability evaluation of some nature generated instability effects and the loss of initial properties or mechanical characteristics influenced by nature the variations and their influence discussed in this paper are not appraised by probabilistic characteristics at the time being. 2 many of metal masts and towers are exploited in the open air in the world nowadays. they have been built many years ago in great numbers. some of them are left without supervision (e.g. in the post-soviet territory). the data of nature monitoring reveals a surroundings pollution growth at the time of exploitation of the structures of that kind. the volume of contaminants that are aggressive to building materials and structures continuously were filled up. this process has activated premature ageing of materials, deterioration of structures, loss of objects viability on the whole. therefore various estimations should include a wider range of problems, factors, after-effects etc. in comparison with those which are taken into consideration and evaluated in high-rise structures design at present. 3 aggressive contaminants provoke an intensification of various destructions on the surface of structural element and in adjacent superficial layers. usually corrosive damages go on spreading under the surface of element more rapidly than on its surface. so, they cannot always be observed in practice. destructive activity of aggressive contaminants include a corrosive eating with following erosion of corroded metal, splitting of thin plates or scales, and forming of micro cracks, ravines etc. 4 the lack of deterministic or probabilistic data stimulate an imitation modelling of structure and its behaviour for reconstruction of its damages gradually step by step. it is a labour-consuming process. the actions of destructions and their combinations may be predicted and analyzed, graphs of possible events and their sequences may be built-up. the problem is suitable for modelling with the computer software. the results of modelling embody basic information for clearing up of undesirable situations generated by polluted surroundings, for revealing rational solutions necessary to undertake on the exploitation phase. 75 journal of sustainable architecture and civil engineering 2016/4/17 an agenda for sustainable construction in europe/ drawn up by the working group for sustainable construction with participants from the european commission, member states and industry. brussels. 2001. baltrėnas, p., morkūnienė, j. 2006. investigation of particulate matter concentration in the air of žvėrynas district in vilnius, journal of environmental 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v. 2011. pollution of “akmenes cementas” vicinity: alkalizing microelements in soil, composition of vegetation species and projection coverage, journal of environmental engineering and landscape management 19(2): 130-139. https://doi.org/10.3846/16486897.2011.579449 šopauskienė, d., jasinevičienė, d. 2004. time series and trends in atmospheric concentrations of journal of sustainable architecture and civil engineering 2016/4/17 76 sulphur and nitrogen dioxides in lithuania in 19812001, environmental and chemical physics 26(3): 100-108. šukytė, v.j., rinkevičienė, e., zelionkaitė, v. 2002. the chemistry of sulphur in anoxic zones of the baltic sea, environmental research, engineering, and management 3(21): 55-60. vaitiekūnas, p., banaitytė, r. 2007. modelling of motor transport exhausts pollutant dispersion, journal of environmental engineering and landscape management 15(1): 39-46. vyzienė, r., girgždys, a. 2009. investigation of aerosol number concentration in jonava town, journal of environmental engineering and landscape management 17(1): 51-59. https://doi. org/10.3846/1648-6897.2009.17.51-59 about the authors jūratė mockienė master degree, lector department of building structures, kaunas university of technology main research area steel structures, strength, durability, destruction, rational design address kaunas university of technology, studentu st. 48, lt51367 kaunas, lithuania tel. +37068227397 e-mail: jurate.mockiene@ktu.lt valerijus keras assoc. prof. dr. department of building structures, kaunas university of technology main research area fracture mechanics, concentration of stresses and strains, durability, destruction address kaunas university of technology, studentu st.48, lt51367 kaunas, lithuania gintaris cinelis assoc. prof. dr. department of building structures, kaunas university of technology main research area computer aided architectural and structural design, caad systems, methods of computer graphics and quantitative analysis in design and engineering, building information modelling address kaunas university of technology, studentu st.48, lt51367 kaunas, lithuania tel. +37068798786 e-mail: gintaris.cinelis@ktu.lt journal of sustainable architecture and civil engineering 2017/3/20 36 *corresponding author: yulia-ivashko@ukr.net the influence of natural landscape and the chinese traditions on the transformations of art nouveau and national romanticism architecture in china http://dx.doi.org/10.5755/j01.sace.20.3.18961 nikolay dyomin, yulia ivashko*, li shuan kyiv national university of construction and architecture, povitroflotski ave. 31, kyiv, ukraine received 2017/09/05 accepted after revision 2017/10/23 journal of sustainable architecture and civil engineering vol. 3 / no. 20 / 2017 pp. 36-47 doi 10.5755/j01.sace.20.3.18961 © kaunas university of technology the influence of natural landscape and the chinese traditions on the transformations of art nouveau and national romanticism architecture in china jsace 3/20 this theme connects with problems of function, protection and restoration of more than 200 objects of the art nouveau heritage in china. the main changes between the european art nouveau and chinese version of art nouveau connected with differences in natural landscape. the specific features of nature in different parts of china explain that the art nouveau objects and objects of north national romanticism in german settlement qingdao with subtropical climate differ strongly from similar objects at russian settlements harbin, shenyang and dalyan in northern-east part of china. different methods are used traditionaly to study historical styles and architectural monuments together with traditional research methods, the main method of the systematic-structural analysis was used for the study. this method determines art nouveau in chinese architecture as a holistic phenomenon with a semantic manifestation at different hierarchical levels. it determined the specifics of the main and regional centers and the creation of a theoretical basis for the protection and restoration of art nouveau objects in china in natural environment. in research was determined at the base of methodology of system-structural analyze that the art nouveau objects in china differs strongly from the european examples of art nouveau and north national romanticism not only in forms but more in natural environment. there is the original situation of existing the brutal gray objects of north national romanticism with granite blocks among the colors of chinese landscape, that is why its determines the protection not only the art nouveau buildings but the natural arrangement too. there are big town territories in china with concentrated location of existing art nouveau objects and actual proposition is to transform these territories into the protective national parks and touristic zones. keywords: art nouveau architecture, china, natural landscape, transformation. 37 journal of sustainable architecture and civil engineering 2017/3/20 introduction since ancient times, the best examples of architecture were those which were not opposed to the surrounding natural environment, but corresponded to it. thus, the egyptian temple complexes in luxor and karnak, as well as the famous complex in giza, are inconceivable without the surrounding desert and exotic vegetation. in other natural and climatic conditions they are simply impossible to imagine. the amazing expressiveness of the greek temple ensembles is largely due to the fact that the acropolis has always been on the highest place, and this is especially seen in the obvious example of the acropolis of athens, where the temples unfold under different angles as one climbs a mountain that dominates the entire urban development. the ensemble of the abbey of mont-saintmichel in france would not have made such an impression, if it had not been the organic fusion of the natural mountain and building, in which the ascending building seems to continue its movement towards the sky with its pointed spire. many styles of architecture for example, baroque 17th-18th centuries, classicism and historicism of the 19th century were reflected in landscape architecture: the examples of versailles, parks of peterhof, pavlovsk, tsarskoe selo, sofiyivka in uman and alexandria in the white church. it can be argued that here architecture and nature are merged together, and scenic natural pictures reinforce the impression of the objects of architecture. of particular importance was the natural environment in the eastern civilizations, primarily in china and japan, where the worldview was brought up by the thousand-year philosophy of shinto and buddhism in japan and taoism and buddhism in china. the main difference between the european and asian approach to assessing the role and place of the natural environment in the aesthetic perception of the architectural object was that in the european culture created by the hands of man (as the crown of the creation of god) was always placed above the created by nature, and the natural environment itself could change according to desire and the needs of man, whereas in the east it was nature, the majestic, the eternal and the infinite, that dominated man and all that he created (). that is why the chinese and japanese objects of architecture have never claimed a leading role and harmoniously blended into the existing natural environment. for the chinese and japanese, the main thing was to merge with nature as much as possible, “letting it into your heart”, because only from awareness of the beauty of nature and the infinite world around one could achieve true enlightenment (levoshko, 2002; orlenko et al., 2016). in many scientific sources devoted to the study of european art nouveau (the works of k. frempton, m. shpaidel, h. fujioki), the idea of the special role of chinese and japanese culture in the formation of european art nouveau as a style in architecture and art is presented. the sources of the art nouveau style were oriental art, traditions of the past (primarily medieval gothic) and avant-gardism. oriental (namely, japanese) art quickly spread to the usa and europe in the 1850s under the influence of certain political events, social and spiritual circumstances. unfortunately, the issue of the influence of the chinese and japanese art on the european art nouveau, as well as the question of the influence of the european art nouveau on the architecture and traditional art of china and japan are still insufficiently studied (ivashko and shuan, 2015). the conducted researches allowed to formulate some conclusions. chinese and japanese culture influenced on european art nouveau in several ways. first of all, artists of art nouveau art borrowed from japanese artists and poets the tradition of spiritualizing nature and the man taking of natural environment, the ability to admire all the phenomena of nature. directly influence on european art nouveau was rendered also by the classical japanese engravings with its smooth silhouettes and a harmonious combination of clearly limited spots and lines, in which natural motifs of curved stems and leaves are also guessed. the chinese and japanese traditions also influenced the spatial concept of art nouveau. one of the most significant influences of japanese culture on the architecture of art nouveau should be considered the application of the principle of communication between the interior and exterior (internal and external space), first used in europe by the belgian architect victor horta, and the principle of transformation and flow of spaces in the interior. journal of sustainable architecture and civil engineering 2017/3/20 38 unlike european buildings that were perceived as “my house is my fortress” and fenced off from nature by the capital walls, the eastern chinese and japanese buildings were not specially fenced off by the walls of the walls, the sliding partition walls were actively used, and the windows of the buildings were opened to the picturesque landscapes mountains, lakes, into the garden. the well-known modernist researcher d. sarabyanov especially stressed that the influence of the oriental worldview took place in the very birth of the modernist style, the strong influence of the east turned out to intrinsic to the style and encompassed all its areas, transformed in accordance with the european perception of the world. directly from chinese and japanese cultures the idea was adopted which became the main for art nouveau: it is the inheritance of nature and the chanting of nature in various kinds of art, the ability to see beauty in every element of nature and in every natural phenomenon. the ideas of universal harmony, the connection of man with the universe and the subordination of man to the universal laws of harmony and beauty found expression in the idea of the eastern house and the artificially created garden. however, in this article we will touch upon an unusual and much less familiar aspect, in comparison with the traditional architecture of the east, namely, as under the influence of the established centuries-old traditions of careful attitude to the natural environment, the european art nouveau style and northern national romanticism changed in the colonial cities on the east coast of china. the acquaintance of japanese artists and writers with the culture of western europe and the art of art nouveau contributed to the reverse process of the penetration of the stylistic features of art nouveau style into traditional japanese culture, and in china, art nouveau received rapid expansion due to the growth of the european settlements in the east coast. however, the processes of penetration of art nouveau style in the conditions of china and japan were not the same: if the modern japanese culture did not have a noticeable influence and wide spread in japan, then in china within the boundaries of the set-up the whole concentrated zones of modernist construction were formed – the influence of meteoric climatic and cultural traditions. thus, a paradox arose: on the one hand, the european figures of art nouveau were inspired by japanese exotics, and on the other hand, japanese artists took art nouveau as a purely european phenomenon, which was already a long-standing cultural tradition of japan. perhaps, the greater favor in the perception of art nouveau in china than in japan was due to the fact that traditional chinese architecture gravitated to splendor and decoration, and japanese architecture to simplicity and asceticism. the actuality of this theme connects with problems of function, protection and restoration of the art nouveau heritage in chinese towns, which consists more than 200 objects. it is necessary to mention the scientific works of l. daping (2016) and v. yang, a. ivanova (2013), t. johston (1996), b. lane miller (2000), s. levoshko (2002), m. marinelli, l. sadovski (2008), w. chaolu (2010) and y. binjiu (2009) and many others, who marked the dominant role of chinese natural and cultural conditions in forming of versions of art-nouveau and north national romanticism in china. but in their scientific researches in whole they describe the architectural objects and more or less the problems of existing of these objects in natural environment. that’s why it is necessary to mark the main role of buddhism and taoism in forming the ancient chinese landscape traditions, because later this chinese original tradition led to the change of the european art-nouveau architecture in chinese settlements. the aim of this research was to analyze the process of transformation the art nouveau and northern national romanticism in china and the role of natural landscape in this process. the main method of investigation was the method of the systematic-structural analysis. the main influence of natural landscape and chinese traditions on of the art nouveau objects in china was determined using this method. methods 39 journal of sustainable architecture and civil engineering 2017/3/20 traditionally, the methods used to study historical styles and architectural monuments were: a complex method of historical-architectural and stylistic analysis (l. polishchuk), a method of field surveys, an analytical method, a method of comparative analysis (s. belenkova), a method of analysis and synthesis, a method of complex architectural modeling, method of typological classification, method of generalization and systematization of results (o. boyko), method of architecture analysis, method of comparative analysis, field surveys, grapho-analytic method (a. harlan). despite all the differences in these methods, all of them combine to produce effective results because they provide answers to questions related to the historical prerequisites for the development of the style, the factors of influence, the identification of unexplored questions, the peculiarities of urban planning and architectural and spatial organization as the basis for the preservation and restoration of monuments. the method of comparative analysis allows us to analyze the specifics of the development of art nouveau in the architecture of china’s cities by identifying the prerequisites, patterns and causes of the appearance of style, identifying the features of the formation and development of art nouveau in chinese architecture and the specific features of the centers of art nouveau on the basis of comparing individual houses of one center, buildings of different centers between themselves and in comparison with the houses of art nouveau style in europe. grapho-analytical method is the basis for comparing the art nouveau centers in china, is the evidence base for the application of the method of comparative analysis and the method of system-structural analysis. together with traditional research methods, the main method of system-structural analysis was used for the study. the systemic approach involves consideration of the main factors of the phenomenon, and the structural approach provides for the separation of the integral object of the interconnecting elements. system analysis examines the whole set of methods, processes and methods for solving the problem (in this case the modification of the european art nouveau style under the influence of chinese natural and climatic conditions and cultural traditions), and the system analysis method provides for the construction of a generalizing model that reflects external factors and the consequence of their action. structural analysis provides for the allocation of an object from the totality of other objects according to the formed system of indicators, the dismemberment of the whole into separate components. the system-structural analysis method views art nouveau in chinese architecture as a holistic phenomenon with a semantic manifestation at different hierarchical levels, which makes it possible to identify the international and national in the art nouveau architecture of china, formulate the defining features of art nouveau in relation to the natural environment, which is the basis for the identification of zones of concentrated location objects of art nouveau style, the determination of the specifics of the main and regional centers and the creation of a theoretical basis for the protection and restoration of art nouveau objects in china in natural environment. in the works of russian and chinese researchers, details of the location of modern objects in harbin and qingdao are described in detail, which makes it possible to speak of the formation of compact areas of modernist construction (daping, 2016). at the same time, in the planning of harbin of the times of russian rule, common principles of russian town planning were introduced at the turn of the century, while the style of modernity itself is present in the architecture of individual objects of various functional purposes. the objects of the modern harbin are compactly concentrated in the form of two local areas, which makes it possible to single out some of the guard zones of the localization of art nouveau with the development of common for these territories monumental and conservation measures. here it is appropriate to quote the publications of the russian researcher s. levoshko (2002), who stressed the direct influence of art nouveau in russia on the construction of harbin and dalian discussion and conclusions journal of sustainable architecture and civil engineering 2017/3/20 40 (fig.1) and the indirect influence of china’s traditional architecture on the development by russian architects of the art nouveau stylistics. most of the construction of the dalian, carried out in the nascent cultural ground that is still inextricably intertwined with art nouveau, can be attributed to “oriental modernity”. chinese traditional architecture (“chinese style”) this is the starting point and source of inspiration for the birth of a new version of russian art nouveau the eastern one. (levoshko, 2002). according to the chinese scientist liu songfy, “art nouveau as a new architectural style of the turn of the 19th and 20th centuries,” linking the past and the future, “marked the beginning, the starting point, of the entry into china of modern western architecture, and harbin became the first city, who accepted it “ (levoshko, 2002). fig. 1 russian version of art nouveau in harbin. the archival photo from the private archive of yulia ivashko unfortunately, a significant part of the unique heritage of art nouveau in harbin is lost (for example, the old railway station building, the dostoevsky school, the dutch consulate, the first restaurant in harbin and some others), so the development of such zones of modernist development, with the establishment of a statutory national monument status is a top priority (ivanova, 2013). some steps in this direction have already been taken by chinese researchers: catalogs of art nouveau objects, passports of objects, dimensional drawings of facades and details, but the fate of many buildings remains unresolved, which is relevant not only for harbin (for example, the former cathedral of christ the savior in the russian military cemetery in shenyang turned into a warehouse, is in emergency condition and only recently was included in the list of monuments of local importance). as mentioned earlier, modernity in qingdao’s architecture differs from modernity in the architecture of harbin, primarily taking into account the fundamentally different, in comparison with harbin, stylistic origins of art nouveau, which is less decorated, more restrained and stylistically close to the north and south german traditional architecture. despite the fact that the main development of qingdao began in 1897-1898, the city’s history actually began in 1891. there are six periods of the development of qingdao from the 1890s and the beginning of the 1950s, but the main period of development of qingdao was the period of german occupation, which began in 1897, when qingdao was regarded as an important naval base in the 41 journal of sustainable architecture and civil engineering 2017/3/20 far east. until this time, the city was called kiaochou (binjiu, 2009; chaolu, 2010; ) and several typical chinese buildings were built there, but the absolute majority of the historic buildings that have survived to this day refer specifically to the period of the german government. in the planning of qingdao according to the scheme of the colony town on the coast by the german authorities, such factors were taken into account: 1) a specific geographical location; 2) good local climatic conditions; 3) picturesque views; 4) terraced landscape with the presence of hills, terraces and natural hills. the problem was only the lack of natural vegetation and natural water sources, so measures were needed to green the hills and organize the city’s water supply. as its development and increase in the flow of large german capital, and hence the development of trade continued, the naval base of qingdao gradually acquired the features of a military-trading colonial city, which in september 1898 was granted the status of an open port of germany, and in 1905 became free trade zone. soon after qingdao was officially handed over by concession to the german government, in 1898 the first master plan of the city was developed, with the main focus of this master plan being a pronounced military function: strategic sites with regular street planning and the availability of buildings to service military functions (binjiu, 2009; chaolu, 2010; ). the second official master plan of qingdao was approved in 1900, and according to a new general plan, a combination of military and trade functions was envisaged, the total area of urban areas was to be 12 square kilometers with a population of 0.1 million inhabitants. the territories in the northern part of the coast were allocated . as an area of purely european development for the residence of german colonists as an area of purely european development for the residence of german colonists (binjiu, 2009; chaolu, 2010; ). at the same time, the second general plan provided for a clear functional zoning of urban areas: the central part of the city was planned in the southern part of the mountain in the northern part of the qingdao coast, the commercial and business part of city life was concentrated in the south along the street. zhongshan road, cuangxi road and taiping road, and the administrative center were provided in the immediate vicinity of the residence of the german governor (kiaochow house of gouvernor), port facilities and docks were on the east side of the coast in the northwestern part of the city to ensure their direct connection with the iron dear kiaochow-hinan. the roads were divided into transport and pedestrian. the terraced building management with natural relief, with orientation of the main facades on the sea, rear facades on the mountain of xin hao (xinhao shan) was assumed. features of the natural landscape determined the tracing of the street system, all the buildings located along the red lines of the streets were to be no higher than three floors and not more than 18 m high, between the houses there were breaks of 3 m (4 m with windows in the end walls). the system of historical urban development of qingdao was finally formed in 1897-1914, during the germanic period, and along with large-scale town-planning measures, the planning of city streets and squares, government buildings, a police department, a prison, a protestant church, several hospitals, banks, office buildings, observatory, post office, telegraph, restaurant, hotels, clubs, schools, villas, port facilities, factories. during the seventeen years of domination (1898-1914), the german authorities consistently gave qingdao the features of an originally german city and during the same period the bulk of urban development was formed. on the basis of the surviving archival drawings and photographs, it can be established that the german colonists conducted systematic work on the planning of the street system and the planting of bare rocky hills and hills, laying the whole system of urban green massifs (fig.2). here journal of sustainable architecture and civil engineering 2017/3/20 42 they had to solve a double task: on the one hand, to embody the symbol of germany in the urban planning and building, on the other to take into account the fundamentally different climatic conditions, the landscape, the local flora. since chinese gardeners were also involved in the gardening process, german regular methods of organizing the natural environment were superimposed on local chinese techniques of garden and park art based on taoism and buddhism. fig. 2 german version of northern national romanticism in quingdao. residence of the governor of qingdao. the archival photo from the private archive of li shuan all this in combination led to a change in the perception of buildings in the style of northern national romanticism, decorative art nouveau and rationalistic art nouveau among exotic greenery. even in the case when the main stylistic features of northern national romanticism (somehow the asymmetric composition of large-scale large volumes, the widespread use of ragged granite, the absence of fine details) were preserved, they were supplemented by a number of features not characteristic of national romanticism, such as: yellow textured plaster, a decrease in the mass of stone facing, the introduction of bright polychromy. it can be assumed that a certain modification of the stylistics of the severe monochrome northern national romanticism in the conditions of china was made by german architects intentionally (fig.2). the main role in the modification of art nouveau style in the conditions of qingdao was played by a specific natural landscape and local natural and climatic conditions, because the art nouveau buildings in qingdao and germany are in many respects similar in form to the basic elements, however they are directly opposite in relation to the natural environment. the chinese garden and park art, formed on the basis of chinese religious teachings, philosophy and worldview, had a special impact on the landscaping of gardens and parks around the art nouveau buildings in qingdao. traditional chinese garden and park art in its philosophical content is more complex and profound than the traditional european garden and park art of the periods of baroque, classicism, historicism, as the chinese garden and park art is aimed at the harmonization of space, which is regarded as an integral part of the universe, and european gardening art serves primarily as a means of aesthetizing and harmonizing the architectural environment and in most cases does 43 journal of sustainable architecture and civil engineering 2017/3/20 not contain a philosophical basis. in the ancient chinese landscape art there is the significance and symbolism of the compositions created, the smooth lines and freedom of growing plants, their unlimitedness through human intervention, the identification of the “hidden meaning” of each landscape environment through small architectural forms located in strictly defined places, stones, inscriptions, philosophical content, the relationship of the natural landscape with different types of art literature, music and painting (landscape as central example product, man as an additional secondary optional image). the strong influence of oriental landscape architecture on european traditions was felt not only on the territory of the eastern settlements: much earlier western europe and the russian empire experienced a fascination with the certain features of the eastern gardens and parks: in the period of baroque, classicism, historicism, romanticism, there appeared columns of sadness, obelisks, park pavilions and “ruins” with philosophical names, “chinese pavilions” and “tea houses”, but it was only a “europeanized” external inheritance of a foreign for europe consciousness of the phenomenon without filling it with philosophical meaning. it is noteworthy that european modernism did not continue this tradition and practically did not manifest itself in original forms in landscape art of the turn of the century (rare examples were the japanese garden of k. monet in giverny near paris and the park güell in barcelona by architect a. gaudi). in most cases, modernist western europe focused on a separate object, rather than on the formation of a greened natural environment. that is why, following the parks of the period of baroque, classicism, historicism and romanticism, it is very difficult to name the same significant parks of the period of the domination of european art nouveau. the explanation for the fact that art nouveau did not pay much attention to garden and park art, as it gave forms, compositions, details, is the following: most of the buildings of european art nouveau were built as objects in the system of tough quarterly development of cities and fewer objects of art nouveau were mansions or objects in the park zone. according to the centuries-old chinese and japanese traditions, the primary, unknowable and eternal is nature, and the object of architecture is secondary to the surrounding natural environment and must be harmoniously inscribed into it. in the eastern mentality, the personal “i” of the european has also been leveled, the person is seen only as one of the components of the surrounding world. the construction of settlements on the territory of china included the establishment of parks and gardens. this is characteristic not only of the subtropical qingdao, but also of the much more northerly russian territories, namely, harbin and dalian. as pointed out in his publications, s. levoshko, dalian’s master plan for the period of russian rule, provided for the organization of a system of urban gardens “upper” and “lower”, as well as several parks, squares and greenery boulevards, which, in her opinion, indicate the introduction of the concept of an ideal “garden city” (levoshko, 2002). a special place in the gardens and parks was allocated to the system of lakes and ponds. in the conditions of a picturesque natural landscape with landscaping, the architectural qualities of the buildings were wiped out, which is also evident in the complex of buildings of the oldest military hospital of the german administration in qingdao. the hospital was built in two stages, for five years, from 1899 to 1904. on several greened hills, five two-storey brick buildings were built, faced with natural stone on the facades. direct influence on the architectural image of local natural and climatic conditions is also evident in the building of the german school for boys in qingdao, which is oriented by its main facade with open terraces on the sea, and especially in the residence of the governor of qingdao (chaolu, 2010). such an influence of exotic eastern nature on the perception of the objects of european archijournal of sustainable architecture and civil engineering 2017/3/20 44 tecture is also noticeable in the objects of the modernist style of japan, which testifies to the common nature of the tendencies with china. as well as around the provincial government in qingdao, around the building of the former german hotel for foreigners in kobe (called “house with a wild boar” due to the large sculpture of a wild boar on the lawn), and now the museum of the arts there is garden and park area with lawn, shorn trees and terraces. it should be noted that in the eastern meaning of greenery, nature is more important than the man-made material environment, including architecture, so the winding greens completely cover one of the towers and part of the building “house with a wild boar,” and the house itself has a second name “green house” (greenhouse). the most outstanding art nouveau objects in china and japan be it the “wild boar house” or the residence of the governor of qingdao, assumed the existence of a vast unoccupied space around the building (for example, the total area of the residence of the governor of qingdao is 26,000 square meters, while the area of the building itself is only 4083 square meters (binjiu, 2009; chaolu, 2010). such a free location of a significant object was determined by the ideological considerations, since the impressive image of the residence of the governor of qingdao (in other words, the qingdao guest house) is largely dictated by a special town-planning arrangement, when the original building itself turns into a city dominant because of its location outside the street, historic building on a hill, namely on the slope of xin hao (xinhao shan, signal hill, dragon mountain), facing the sea. it ca be seen how the construction of a residence on a hill with the possibility of its viewing from different points, from above and from below, contributes to the multiple reinforcement of its figurative perception, since in this case the natural landscape is actively included in the formation of the “architectural landscape” (binjiu, 2009; chaolu, 2010). the installation of the main qingdao building at this place, on the southern slope of the xin hao mountain, served both as the embodiment of the german presence and the bridge of communication with local beliefs according to which the mountain with the lair of the sacred dragon underground was mysterious, and the roads along the southern slope of the mountain, leading to the residence of the governor and linking it with the foot of the mountain, were called “dragon” even during the german domination fig. 3 residence of the governor of qingdao. photo of li shuan, 2014 45 journal of sustainable architecture and civil engineering 2017/3/20 of the city (binjiu, 2009; chaolu, 2010). the symbolic image of the dragon has occupied a special place in chinese mythology, philosophy and culture since ancient times (chinese trad., 龙, pinyin: lóng, pall: moons). chinese dragon-king of animals, symbol of the power of the emperor, unlike the predatory european dragon-serpent embodied the good beginning of yang, symbolized the elements of water and personified the chinese nation. according to the ancient chinese tradition, the lakes and ponds were an indispensable element of the palace complexes, and the european habitat on the dragon mountain, where a common visual composition included a water surface with a bridge and a natural relief, as well as a well-groomed landscaped park with green terraces, was no exception. in the building of the residence, the image of the dragon is embodied not only in the name of the mountain, but also in the head of the dragon that is hung from the eaves of the roof above the central entrance of the residence. it shows the direction to germany, the homeland of the german governor oscar van leo boyer, under which the residence was built. the image of the dragon is characteristic not only to the chinese mythology and the germanic epic, but also to the european modernity, where images of fantastic creatures, including dragons and snakes, are widely represented. thus, it can be argued that, on the exotic chinese soil, the specific chinese mythology has organically blended into the european modernism in china. mysticism is present not only in the location of the residence on the sacred mountain, but also in the presence of some elements in the building, such as the mystical columns of yang tai shan in the gallery, which perform not only constructive and aesthetic but also hidden mystical functions, namely, to protect the city and residence from foreign invaders. the architect carefully thought out how the building would be perceived from different points: thus, when viewed from the top points of the mountain, a view of the governor’s residence opens with a combination of bright tented and sloping red and green tiled roofs with stone chimneys and chinese red wooden details, gray inclusions of natural stone, yellow textured walls and arched galleries with round pillars supporting the arches. particularly important is the composition of the markedly massive, different altitude tower volumes. some roofs have a profile reminiscent of chinese roofs, which demonstrates the transformation of modernity in china and the synthesis of european art nouveau and traditional chinese architectural style. the building of the residence of the governor of qingdao was built on the most advantageous part of the xin hao mountain and is fully visible not only from the top of the mountain, when the “fifth facade” plays a special role in perception the top view, but also from below, from the small stone bridge of the daksu road at the foot of the mountain facade. from the bottom, the residence is perceived as a roman castle in a dense greenery, and here there is the effect of visual illusion the building seems visually larger in size, higher, massive and majestic than it actually is. it becomes understandable the intention of the german authorities, who were not satisfied with the already existing buildings in the city before the german period and did not place the residence of the governor in the urban development system. it was necessary to create the unique image of the main government building-symbol of the german presence in china, expressing this primacy and importance in both architecture and location (fig.3). the residence was built for three years, and during these three years systemic gardening of the surrounding area was carried out, as, as can be seen from the archive black-and-white photographs, the mountain was originally not particularly green. over the time, the green mass grew, and the slope was greened in the following years, and today the southern slope of mountain xin hao is completely different from what it was at the turn of the century. the main changes between the european art nouveau and chinese version of art nouveau are connected with differences in natural landscape. the european objects were situated in the regular town-planning system without trees and parks. the main feature of traditional chinese archijournal of sustainable architecture and civil engineering 2017/3/20 46 conclusions tecture forming in continue of centuries was the organic connection between nature and building with the domination of natural landscape. this has determined that the town-planning situation in chinese centres of art nouveau and national romanticism architecture differ so strongly from the european town-planning situation. chinese objects in most cases situated in parks and in architectural complexes dominate the natural landcsape with picturesque hills, exotic trees and flowers and lakes with golden fishes. the specific features of nature in different parts of china determined the impression of art nouveau objects (the art nouveau objects and objects of northern national romanticism in german settlement qingdao with subtropical climate differ strongly from similar objects at russian settlements harbin, shenyang and dalian in nortern-east part of china). really, the changing landscape was the main reason for the transformation of the european architectural style for chinese conditions. the scientific novelty of research: _ the role of nature conditions and natural landscape in the process of transformation the art nouveau architecture in chinese settlments was argued and analyzed in complex; the art nouveau objects in china are surrounded by the picturesque gardens with exotic plants; _ using the methodology of system-structural analysis it was determined that the art nouveau objects in china differ strongly from the european examples of art nouveau and northern national romanticism not only in forms but more in natural environment. there is the original situation of existing the brutal gray objects of northern national romanticism with granite blocks among the colors of chinese landscape. that’s why its determines the protection not only the art nouveau buildings but the natural arrangements too; _ the existing art nouveau objects in china along the natural landscape led to transformations of the territories into the protective national parks and touristic zones. thus, all this proves that the main difference between european art nouveau and art nouveau of china is that in european architecture a single object and its separate elements dominated, and in the cities-colonies in china the predominant role was played by the natural environment that was included in the overall composition and altered the perception of the familiar morphology of the modernist forms. if you try to find analogues of this situation among the european examples of art nouveau, then park güell in barcelona, designed by the architect antonio gaudi, built by the order of the aristocrat and industrialist eusebio güell, reveals the greatest commonality with the objects of modern architecture of china and japan secondary to the natural landscape. park güell is much closer to the objects of modernism in china and japan in the garden and park environment than the traditional european houses of art nouveau in the rigid system of perimeter building of blocks without greenery. the similarity of approaches to the interconnection of the building and the surrounding natural landscape in spain, china and japan is due to the fact that in spain the traditions of landscape architecture have long developed from moorish architecture, where special attention was paid to the greening of internal courtyard spaces and the inclusion of water in the general composition. therefore, it can be concluded that the style can be modified not only by changing the volume-spatial composition, the shape of the elements, but also by incorporating the natural environment that radically affects the perception of objects of the same style (for example, the residence of the governor of qingdao and similar in style to objects of northern national romanticism of finland in the system of rigid quarterly building of streets). this can be seen when comparing the old photos of the governor’s residance on the slope of an undeveloped mountain and modern photographs of the residence, when it is almost impossible to photograph the facades entirely because of the overgrown landscape park from characteristic chinese tree species. 47 journal of sustainable architecture and civil engineering 2017/3/20 binjiu y. german architecture in oingdao. china architecture and building press, 2009. chaolu w. fifty old constructions in qingdao. 2010. daping l. art nouveau architecture in harbin. 刘大 平, 王岩. :哈尔滨新艺术建筑. harbin, hitpress 哈 尔滨工业大学出版社, 2016. johston t., erh d. far from home. western architecture in china’s northern treaty ports. hongkong, 1996. 429 p. sadowski l. architektura europejska w chinach od połowy xix wieku do 1937 roku. sztuka dalekiego wschodu. studia. warszawa, 2008. s.145-154. иванова а.п. архитектура китайских сеттльментов: к проблеме культурных стратегий дальневосточной колонизации. [ivanova a.p. the architecture of chinese settlements: for problems of the cultural strategy of the far east colonization. the herald of the pacific ocean university]. вестник тихоокеанского государственного университета. 2013. №3 (30): 129-138. references ивашко ю., ли шуань. модерн западной европы, украины и китая: пути трансформации и имплементации. [ivashko yu., li shuan. the art nouveau style in western europe, ukraine and china: the ways of transformation and implementation]. киев: феникс; 2015. левошко с.с. историко-культурное исследование харбина. архитектура восточной сибири. русские города на дальнем востоке. [levoshko s. the historical cultural heritage in harbin. the east siberian architecture. russian towns at the far east] хабаровск, 2002. вып. 1.: 167-192. орленко н.и., ивашко ю.в., ли шуань. реинкарнация северного национального романтизма: исследование и опыт реставрации объектов. [orlenko n., ivashko yu., li shuan. the reincarnation of the northern national romanticism: studying and experience of restoration of objects] киев: феникс; 2016. nikolay dyomin doctor of architecture, professor, president union of urbanists of ukraine vice-president ukrainian academy of architecture head of the department town building at kiev national university of construction and architecture, construction faculty main research area urban planning address kiev national university of construction and architecture, povitroflotsky ave., 31, kyiv, ukraine tel. 067-4 41-85-20 yulia ivashko doctor of architecture, professor kiev national university of construction and architecture, the department of the basis of architecture and architectural projecting main research areas the art nouveau architecture, the architecture of historicism of the 19th century, the traditional wooden architecture, the chinese architecture address kiev national university of construction and architecture, architectural faculty, povitroflotsky ave., 31, kyiv, ukraine tel. 099-313-66-20 e-mail: yulia-ivashko@ukr.net li shuan architect kiev national university of construction and architecture, the department of the basis of architecture and architectural projecting main research areas the trаditional chinese architecture, the art nouveau architecture in china address kiev national university of construction and architecture, the architectural faculty, povitroflotsky ave., 31, kyiv, ukraine tel. 099-313-66-20 about the authors 69 journal of sustainable architecture and civil engineering 2018/2/23 *corresponding author: rokas.valancius@ktu.lt analysis of the criteria for selecting heating systems for residential buildings in cold climate received 2018/08/08 accepted after revision 2018/09/26 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 69-78 doi 10.5755/j01.sace.23.2.21359 analysis of the criteria for selecting heating systems for residential buildings in cold climate jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.21359 jurgita cerneckiene, rokas valancius*, laura stasiuliene kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania eugenijus perednis lithuanian energy institute, laboratory for renewable energy and energy efficiency breslaujos str. 3, lt-44403 kaunas, lithuania juozas vaiciunas kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania introduction how to choose a heating system for a residential building? that is an important question for builders and owners of the buildings in lithuania. approximately the heating season in lithuania starts by october 15th and ends on april 15th. during this period, the average outdoor air temperature is about 0°c. many of the new single-family buildings in lithuania are sold not completed as the new owners want to be free in choosing interior materials and engineering equipment. for this reason, many engineering decisions must be taken by the owner of the building, who is usually not a professional in the field of engineering. when choosing a heat source, it is always necessary to distinguish between many “for” and “against” arguments. every heating option has both advantages and disadvantages. there is also a striking balance: the same heating method can never be either very comfortable and at the same time very cheap. when making a final decision, it is always recommended to compare the ratio of heat to the price and comfort, of course, taking into account energy and fuel price forecasts. the article provides information that helps the building owner to navigate in the field of different engineering solutions that affect the future maintenance costs, efficiency, environmental aspects and comfort level of the building. keywords: residential building, heating system, energy prices. the building sector accounts for 40% of the final energy consumption and 36% of co2 emissions in lithuania and eu countries (european commission 2018). space heating and hot water accounts for about 26% of all final energy consumption in the eu (bosh et al. 2008). european commission has set the new target of reducing the co2 emissions by 90% for the building sector by the year 2050 (european commission 2011). as reported in the 2014/15 european work program, more than 17% of the primary energy savings potential of the eu for 2050 (european commission 2015) to the building retrofit is related. the largest part of buildings in lithuania was built in the second part of 20th century. about 60% of lithuanian population resides in multi-family buildings constructed during 1961–1990. about 40% of people in lithuania lives in one or two-family buildings (ehpa 2017). journal of sustainable architecture and civil engineering 2018/2/23 70 approximately heating season in lithuania starts by october 15th and ends on april 15th. according lithuanian legislation for thermal energy supply and consumption heating season can be started when the average outdoor air temperature is below +10 °c for three consecutive days, and complete when the temperature is three consecutive times higher than + 10 °c (rules for supply and consumption of thermal energy). during this period, the average outdoor air temperature is about 0 °c. according to the regulations comfort temperature in living rooms and offices during a heating season should be in the range of 18 to 22 °c. average energy consumption for space heating is 101kwh/ m2, domestic hot water heating takes 11.2kwh/m2 and 75.1kwh/m2 is used for other’s needs (ehpa 2017). compared to the other eu countries with similar climate conditions, energy consumption for residential heating is approximately 1.8 times higher in lithuania (streimikiene 2014). the survey (eso 2017) performed in 2016 showed that in the major lithuanian cities two-thirds of the population use centralized district heating (cdh), the remaining gas heating (18%) or solid fuel firewood or charcoal (15%). other heat sources, such as electricity, geothermal heating or pellet boilers, are used by a very small proportion of the population. according to the results of the survey, the choice of the heating method is influenced by the price and convenience. the priority for these heating criteria was provided by 42% and 39% of respondents during the survey, respectively. the comfort was especially emphasized by those residents whose home was heated by natural gas (44%), but the price was also a very important factor for them (38%). when choosing a heating source, it is always necessary to distinguish between many arguments. clearly, every heating option has both advantages and disadvantages. this article aims to provide information that helps the building owner to navigate in the field of different engineering solutions that affect the future maintenance costs, efficiency, environmental aspects and comfort level in the building. climate conditions of lithuania lithuania has typical european continental climate with warm, dry summers and fairly severe winters. january is the coldest month with daytime temperatures usually around -5 °c. however, periods with temperatures of about -20 °c or above 0 °c can last for few days or weeks. furthermore, heavy snowfall or even snowstorms are also possible. the weather is often windy, cold and humid due to proximity to baltic sea. temperature in summer can reach 20-25 °c. july is the warmest month with an average temperature of 18 °c. temperature peaks above 30 °c can occur and last for few weeks. rain with heavy thunderstorms is common occurrence. on another hand, climate change cannot be ignored; winters are getting warmer with only a few days or weeks with snowfall. according to lithuanian regulations it is still recommended to use a climatic data from 1961 to 1990 (rsn 156-94) although official data from later period (average temperature of period 19812010) also exists (galvonaitė a. et al). the average temperatures in kaunas city are presented in table 1. these temperatures are near the average values of lithuania with 0.7÷0.8 deviation from lithuanian average values. (galvonaitė a. et al) table 1 average (19812010), highest and lowest (19001990) monthly temperature in kaunas city temperature, °c month 1 2 3 4 5 6 7 8 9 10 11 12 avg. (7.25) -3.25 -3.25 0.75 7.25 12.75 15.75 18.25 17.75 12.75 7.75 1.75 -2.25 highest 9.3 14.8 20.2 27.9 31.4 32.8 34.9 34.7 29.7 23.9 16.7 11.1 lowest -35.8 -36.3 -26.3 -12.0 -4.9 -0.2 4.4 0.3 -3.2 -13.7 -22.5 -28.5 71 journal of sustainable architecture and civil engineering 2018/2/23 lithuanian energy market is quite unique in the european context; district heating occupies more than 55% of the total thermal market (lsta 2011). quite frequently, natural gas 11.9%, biofuel 25%, coal 5.2% or in some cases electricity 0.22% is used for building heating systems (ehpa 2017). the average price of district heating in lithuanian cities is 0.05€/kwh (table 2). in recent years, district heating energy price dropped by 8% (lsta 2018). switching from natural gas to biofuel reduced the district heating energy price significantly in the last five years. due to a dramatic decline in oil and natural gas prices, conventional fuel prices also decreased by 35% in the last five years. global events show that in the near future, the price of energy tends to increase. in 2017 natural gas prices in lithuania for citizens varied from 0.38 to 0.64€/m3, depending on the consumption per year. electricity prices varied from 0.077 to 0.124€/kwh, depending on a selected tariff (regula 2018). the international situation in the price of biofuels (firewood) does not have an important direct impact, but the price of petroleum products has, as these are needed for the production of biofuels and transportation. therefore, it is also expected that prices will increase in the field of biofuel. despite the minor fluctuation in recent years, it is noticeable that traditional energy (biofuel, natural gas, electricity, centralized district heating) prices are increasing slowly. energy prices in lithuania the influence of the heating system and the heat source to the energy efficiency of the building table 2 energy price dynamics in 20152017 (vat incluted) year eur/mwh cdh 1) natural gas 2) electricity 3) firewood 4) wood pellets5) 2015 62.6 45.2 127.0 31.6 37.8 2016 57.1 41.9 113.0 35.5 33.0 2017 50.1 40.3 113.0 37.3 36.5 there are different traditions of purchasing of residential buildings in different countries. it is popular to buy a residential building with unfinished construction works in lithuania as the owner feels free to make most acceptable interior and building comfort solutions. one of the decisions that owners prefer to make according their lifestyle and employment is selecting the heat source. apart from other criteria discussed in the paper, it is necessary to evaluate how the selected heat source influences the overall energy efficiency of a building. the energy efficiency of a building (energy performance class epc) is a state-regulated criterion, introduced as one of the means to implement the adopted cross-border agreements (directive 2010/31/eu) and thus to manage climate change. the energy performance class of buildings, that has the building permit issued after 1st january 2016, should not be lower than a, after 1st january 2018 not lower than a+ and after 1st january 2021 energy performance class must reach a++ class (str 2.01.02:2016). during the energy performance assessment, the building is analyzed according to 7 criteria for classes a and a+ and 8 criteria for class a++. heat source used in heating and domestic hot water systems has direct influence for two criteria used in a and a+ evaluation and for 3 criteria in a++ evaluation. in most cases, the selection of heat source for a building and the modeling of its energy performance class is already provided during the design stage. therefore, it is important for the owner of 1) average cdh energy price for residents (lsta 2018); 2) the price of energy from natural gas for residents using from 500m³ to 20 000m³ of gas per year (regula 2018); 3) one-time zone tariff, “standard” source (regula 2017); 4) the price of energy from chopped birch firewood with 20% humidity; 5) the price of energy from deciduous trees wood pellets. journal of sustainable architecture and civil engineering 2018/2/23 72 the building to know if the heating alternative he wants to choose is not worse than the designed case. for example, for a residential building of 150m2 with specific heat losses of 82.39w/k, natural ventilation, and a heat pump used for heating (with thermal energy source – air) – energy performance class a+ would be qualified. if the owner would change the designed heat source into solid fuel or gas boiler, such building would be qualified as a b class building. one of the quantitative indicators according to which the owner can compare different heating sources is the calculated efficiency of the building heating system ηhs, which is calculated according to the formula (str 2.01.02:2016) the selected heat source influences the overall energy efficiency of a building. the energy efficiency of a building (energy performance class epc) is a state-regulated criterion, introduced as one of the means to implement the adopted crossborder agreements (directive 2010/31/eu) and thus to manage climate change. the energy performance class of buildings, that has the building permit issued after 1st january 2016, should not be lower than a, after 1st january 2018 not lower than a+ and after 1st january 2021 energy performance class must reach a++ class (str 2.01.02:2016). during the energy performance assessment, the building is analyzed according to 7 criteria for classes a and a+ and 8 criteria for class a++. heat source used in heating and domestic hot water systems has direct influence for two criteria used in a and a+ evaluation and for 3 criteria in a++ evaluation. in most cases, the selection of heat source for a building and the modeling of its energy performance class is already provided during the design stage. therefore, it is important for the owner of the building to know if the heating alternative he wants to choose is not worse than the designed case. for example, for a residential building of 150m2 with specific heat losses of 82.39w/k, natural ventilation, and a heat pump used for heating (with thermal energy source – air) – energy performance class a+ would be qualified. if the owner would change the designed heat source into solid fuel or gas boiler, such building would be qualified as a b class building. one of the quantitative indicators according to which the owner can compare different heating sources is the calculated efficiency of the building heating system ηhs, which is calculated according to the formula (str 2.01.02:2016) reghs k .221   , where η1 coefficient of the heating system automatic regulation level (table 3), η2 coefficient of the thermal efficiency of the heat source (table 4), k2.reg correction factor for evaluating the efficiency of a heat source when coefficient of the efficiency is declared by the producer of the heat source (table 5). table 3. the coefficients of the heating system automatic regulation level η1 regulation equipment η1 no regulation equipment 0.88 regulation equipment controls the heating system in the whole building: only thermostatic regulators for heat emitters or inside/outside thermostat are installed 0.93 regulation equipment controls the heating system in the whole building: both thermostatic regulators for heat emitters and inside/outside thermostat are installed 0.98 regulation equipment controls the heating system in the part of the building 0.90 table 4. the coefficients of the thermal efficiency of the heat source η2 heat source η2 heat source η2 central heat networks, manual regulation 0.90 electric heating, manual regulation 0.90 central heat networks, automatic regulation 1.00 electric heating, automatic regulation 1.00 gas boiler, manual regulation 0.80 heat pump, energy taken from the air ηspf = 3.00 gas boiler, automatic regulation 0.94 heat pump, energy taken from the soil ηspf = 4.00 radiant gas heater 1.00 heat pump, energy taken from the water ηspf = 4.50 liquid fuel boiler, manual regulation 0.75 furnaces 0.50 liquid fuel boiler, automatic regulation 0.87 open fireplace 0.20 solid fuel boiler, manual regulation 0.70 fireplaces with a capsule, when the combustion process uses warm indoor air 0.30 solid fuel boiler, automatic regulation 0.85 fireplaces with a capsule, when the combustion process uses outdoor air 0.50 table 5. correction factors k2.reg for evaluating the efficiency of a heat source when the coefficient of the efficiency is declared by the producer of the heat source heat source k2.re gas boiler 0.85 liquid fuel boiler 0.86 solid fuel boiler 0.82 electric heating 0.90 other cases 1.00 (1) where η1 coefficient of the heating system automatic regulation level (table 3), η2 coefficient of the thermal efficiency of the heat source (table 4), k2.reg correction factor for evaluating the efficiency of a heat source when coefficient of the efficiency is declared by the producer of the heat source (table 5). table 3 the coefficients of the heating system automatic regulation level η1 regulation equipment η1 no regulation equipment 0.88 regulation equipment controls the heating system in the whole building: only thermostatic regulators for heat emitters or inside/outside thermostat are installed 0.93 regulation equipment controls the heating system in the whole building: both thermostatic regulators for heat emitters and inside/outside thermostat are installed 0.98 regulation equipment controls the heating system in the part of the building 0.90 table 4 the coefficients of the thermal efficiency of the heat source η2 heat source η2 heat source η2 central heat networks, manual regulation 0.90 electric heating, manual regulation 0.90 central heat networks, automatic regulation 1.00 electric heating, automatic regulation 1.00 gas boiler, manual regulation 0.80 heat pump, energy taken from the air ηspf = 3.00 gas boiler, automatic regulation 0.94 heat pump, energy taken from the soil ηspf = 4.00 radiant gas heater 1.00 heat pump, energy taken from the water ηspf = 4.50 liquid fuel boiler, manual regulation 0.75 furnaces 0.50 liquid fuel boiler, automatic regulation 0.87 open fireplace 0.20 solid fuel boiler, manual regulation 0.70 fireplaces with a capsule, when the combustion process uses warm indoor air 0.30 solid fuel boiler, automatic regulation 0.85 fireplaces with a capsule, when the combustion process uses outdoor air 0.50 table 5 correction factors k2.reg for evaluating the efficiency of a heat source when the coefficient of the efficiency is declared by the producer of the heat source heat source k2.re gas boiler 0.85 liquid fuel boiler 0.86 solid fuel boiler 0.82 electric heating 0.90 other cases 1.00 73 journal of sustainable architecture and civil engineering 2018/2/23 if the efficiency of the selected heating system alternative of the building ηhs is not lower than the one according which the energy performance class of the building has been modeled, the user can make a decision without additional calculations, otherwise it is necessary to make additional calculation and check if the requirements of the legislation are met. due to unfavorable results of calculations, i.e., when the required energy performance class cannot be achieved, it may be necessary to increase the insulation layers of the building partitions or maintain a design heat source. table 6 description of heating system alternatives according to different criteria heating source criterion space for equipment smooth/fast power control daily maintenance local environment pollution solid fuel (firewood) boiler without accumulation tank ~ 6m2 + space for firewood storage (required area depends on the amount of firewood that is needed to accumulate) uneven power regulation bringing firewood to the boiler room, removing ashes a significant amount of particulate matter, carbon dioxide, nitrogen oxides are released into the local environment solid fuel (firewood) boiler with accumulation tank ~ 8m2 + space for firewood storage (required area depends on the amount of firewood that is needed to accumulate) accumulation tank ensures smooth power control wood pellet boiler ~ 8m2 + space for wood pellet storage (required area depends on the amount of wood pellets that is needed to accumulate) wide power regulation filling wood pellet tank, removing ashes natural gas boiler (condensing boiler with heat exchanger for domestic hot water) up to 2m2 wide and smooth power regulation no need an insignificant amount of particulate matter, carbon dioxide, nitrogen oxides are released into the local environment heat pump, type “air to water” up to 4m2 no local pollution heat pump, type “soil to water” up to 4m2 centralized district heating up to 2m2 criteria for selecting heating systems for residential buildings the other criteria according to which decision of heating source selection can be made are more related to habits and individual situation of a resident. one of these criteria is space for equipment, which is essential for modern homes. it is important to emphasize that the peculiarities of daily maintenance remain an urgent issue for building residents. furthermore, environmental pollution has long been ignored; nowadays local environment pollution is one of the most important criteria. to have a more reliable heat source, an additional (alternative) heat generator is often considered. therefore, the chosen heat source should be compatible with other alternatives. in this case, the heat source is a boiler room, i.e., components, that can vary widely depending on the selected heating type. meanwhile, the heating system includes pipelines with heating devices or without them (in underfloor and panel heating systems). detailed descriptions of different heating system alternatives are presented in table 6. journal of sustainable architecture and civil engineering 2018/2/23 74 the solid fuel boiler room consists of a solid fuel boiler, a stack unit, a storage tank for heat storage, a domestic hot water tank, circulating pumps, regulating equipment, controller, and pipelines. in recent years, the level of automation of solid boilers has been improved, which has simplified boiler care and increased system efficiency (cerneckiene et al. 2018). the natural gas boiler room is the simplest. gas boiler can be installed in the kitchen or bathroom. on the other hand, specific technical requirements for a room must be fulfilled before gas boiler installation. the height of the room must be at least 2.2m. the room must have a window of 0.05m2 for each cubic meter of the room. if the volume of the room is 20.0m3 or more, the window area must be at least 1.0m2. in most cases the gas boiler with domestic hot water preparation function is mounted on the wall, and the pipelines from the heating system as well as gas supply pipe are connected to the boiler. this option of the gas boiler was evaluated in further calculations. evaluating the alternative heat source the heat pump, the underground collector (horizontal or vertical) in the yard must be included in the boiler room installation. instead of underground collector outdoor air can be used as heat source. however, in cold climates efficiency of this type of heat pump is lower (honkapuro and koreneff 2017; stuart et al. 2013). other elements of the boiler room with the heat pump are the heat pump module with compressor and circulation pumps, the domestic hot water tank and other auxiliary boiler control equipment. an important factor is that heat pumps work effectively only with low-temperature heating systems, e.g., underfloor heating. the boiler room is very compact for those buildings that can connect to district heating network: it consists of the equipment for reducing the district water parameters (temperature, pressure, etc.), a heat exchanger for heating systems as well as for domestic hot water system, circulating pumps, thermal energy accounting devices. there are other heating types such as direct electric heating, liquid gas boilers or liquid fuel boiler. however, due to the low popularity of such heating types in recent years, these heating types were not evaluated. the economic benefit is often the most urgent issue when evaluating and choosing the source of heat generation. the economic benefit in this study was estimated by calculating the discounted price of thermal energy. it is an economic indicator that estimates cost over a period of 10 years. it was assumed that the temperature in the building is +20°c and the annual heat demand for heating and hot water is 15,000kwh. it was also assumed that the entire cost of the heating system is covered during the installation. the lifespan of the heating system was considered to be ten years. parameters used for financial assessment of the heating systems are presented in table 7. investments into the heat source vary widely and depend on the chosen equipment, manufacturer, the level of automation, cost of gas, cost of energy from district heating and the complexity of the installation work. average investment into a heating source of 150m2 a class single-family building in lithuania with underfloor heating is presented in table 8. investments in the heat source table 7 parameters used for economic calculations the lifespan of the heating system, years 10 specific district heating energy price (average), eur/kwh 0.050 specific energy from natural gas price (average), eur/kwh 0.040 specific energy from solid fuel (average), eur/kwh 0.047 specific energy from wood pellets (average), eur/kwh 0.106 specific electricity costs (standard), eur/kwh 0.113 index for energy prices, % per year 2.0 interest capital, % 2.5 running costs, % 1.5 75 journal of sustainable architecture and civil engineering 2018/2/23 table 8 average investments into a heating source of 150m2 a class single-family building in lithuania with underfloor heating heating source average primary installation cost, eur fuel cost for the 10-year period, eur total installation and fuel cost for the 10-year period, eur solid fuel (firewood) boiler without accumulation tank 1800 6249 8566 solid fuel (firewood) boiler with accumulation tank 4300 5873 11441 wood pellets boiler 4100 5809 11089 condensing gas boiler with heat exchanger for domestic hot water 2900 7490 10849 heat pump, type “air to water” spf*=3.5 6500 5504 12349 heat pump, type “soil to water” spf*=4.5 11800 4526 16750 centralized district heating 3200 8377 12304 * seasonal performance factor were evaluated by comparing prices of at least three suppliers (gas and district heating) during the first quarter of 2018 in kaunas city. it was assumed that distance (connection length) from the building to the gas or district heating network is up to 10m. in lithuania, some limited subsidy systems and funds for renewable energy installations exists since 2005. depending on a project, it is possible to apply for a subsidy covering from 25 to 100% of initial costs. for example, it is possible to get a subsidy up to 30% for the single-family building (but only for buildings older than five years), up to 40% for multifamily buildings and up to 100% for hospitals. in this study subsidy for a heat source installation were not assessed. the obtained data (fig. 1) shows that heating systems with solid fuel or wood pellets boilers are the cheapest way to cover the heating and domestic hot water demand of the residential building, especially if it is possible to buy firewood cheaper than the average market price. the average results in lithuania, some limited subsidy systems and funds for renewable energy installations exists since 2005. depending on a project, it is possible to apply for a subsidy covering from 25 to 100% of initial costs. for example, it is possible to get a subsidy up to 30% for the single-family building (but only for buildings older than five years), up to 40% for multifamily buildings and up to 100% for hospitals. in this study subsidy for a heat source installation were not assessed. results the obtained data (figure 1) shows that heating systems with solid fuel or wood pellets boilers are the cheapest way to cover the heating and domestic hot water demand of the residential building, especially if it is possible to buy firewood cheaper than the average market price. the average energy price of this system for the 10-year period (without installation cost) is 0.040eur/kwh. the most expensive heating system is a system with a heat pump (type “soil to water”). however, if investments in the installation of this type of heating system are not evaluated, this type of heat source would give an energy price of 0.029eur/kwh. regarding the comfort level, the least comfortable heat source would be solid fuel boilers. due to the daily maintenance of the boiler, i.e., it is necessary to bring firewood to the boiler room, clean the boiler or remove the ashes every day. it can be argued that gas boiler or centralized district heating as a heat source are the most attractive regarding comfort, investment, and energy costs for the 10-year period. however, natural gas or district heating networks are not available in all areas. therefore, choosing a heat source for a building that cannot be connected to the natural gas or district heating networks and at the same time seeking to achieve comfort and ecological environment, a better choice would be to use “air to water” heat pump. the energy price of this system is higher and exceeds 0.036eur/kwh excluding installation. however, the investments in this system are lower by 50% compared to “soil to water” heat pump system. figure 1. energy prices for heating (vat included). recommendations for the selection of the heat source for a residential building in a cold climate country are presented in figure 2. the figure shows quick evaluation of possible heating alternatives and gives qualitative and quantitative comparison of different types of heating. the efficiency of the heating system of the building (ηhs) is calculated evaluating possible manual and automatic regulation both of the heating source and heating system. it is noticeable that automatic regulation and additional equipment plays an important role in the whole system evaluation, because automatically regulated system with a solid fuel boiler and accumulation tank (ηhs=0.686) can be near to the condensing gas boiler without automatic regulation (ηhs=0.704). quantitative data for the grade evaluation of the heating system installation and exploitation costs is taken from table 8. grade “1” indicates the lowest cost level and grade “7” indicates the most expensive implement. analyzing the data presented in figure 2 it should be noted that because of the rising economic situation in the country, increasing income and people business ones of the most important criteria for choosing the most suitable heating fig. 1 energy prices for heating (vat included) journal of sustainable architecture and civil engineering 2018/2/23 76 fig. 2 recommendations for the selection of the heat source for a residential building in a cold climate country system is its reliability and efficiency. operating costs of the heating systems are not so important as it was 10 or 15 years ago. the data presented in this study reflects the current state of installation and operation of heating systems. it is assumed that the situation will change slightly in the future. looking at the prospect of 20-30 years, oil and its price will be a major and decisive factor in the global economic development. changes in oil prices will affect natural gas, energy for transport and other energy sources prices. the data presented in figure 2 should be relevant in the future while selecting the heating system for residential buildings. figure 2. recommendations for the selection of the heat source for a residential building in a cold climate country conclusions due to good infrastructure, lithuanian consumers usually have many alternatives in choosing a heat source – from district heating to the gas boilers. many objective and subjective criteria should be taken into account in order to determine the most suitable heat source. the main criteria that should be evaluated are: installation and exploitation costs, daily maintenance needs, additional space for the equipment and the influence of selected heat source to the energy efficiency of the building. the lowest installation and fuel cost for the 10-year period can be reached by using solid fuel (firewood) boiler without accumulation tank (8566eur) if daily maintenance of the boiler is acceptable. when the infrastructure of gas supply network is available a condensing gas boiler with heat exchanger for domestic hot water can give minimal centralized district heating network natural gas network no special infrastructure for heating ex is tin g in fr as tr uc tu re eq ui pm en t individual heating substations condensing gas boiler with heat exchanger for domestic hot water heat pump type: ‘’air to water” spf=3.5 solid fuel boiler wood pellets boiler ef fic ie nc y of th e he at in g sy st em o f t he bu ild in g, η hs 2.790 ÷ 2.940 0.748 ÷ 0.833 0.616 ÷ 0.686 0.616 d ai ly m ai nt en an ce ne ed s not required not required not required depends on outdoor conditions and equipment from 2 times per week depends on outdoor conditions and equipment from 2 times per week depends on outdoor conditions from 2 times per day pr im ar y in st al la tio n co st in gr ad es * 3 2 6 7 4 5 1 fu el co st s in gr ad es * 7 6 2 1 3 4 5 co m m on in st al la tio n an d fu el co st s fo r 1 0ye ar p er io d* 5 2 6 7 3 4 1 *1-lowest, 7-highest 0.792 ÷ 0.980 0.704 ÷ 0.920 type: ‘’soil to water” spf=4.5 solid fuel boiler with accumulation tank solid fuel boiler without accumulation tank 3.720 ÷ 3.920 energy price of this system for the 10-year period (without installation cost) is 0.040eur/kwh. the most expensive heating system is a system with a heat pump (type “soil to water”). however, if investments in the installation of this type of heating system are not evaluated, this type of heat source would give an energy price of 0.029eur/kwh. regarding the comfort level, the least comfortable heat source would be solid fuel boilers. due to the daily maintenance of the boiler, i.e., it is necessary to bring firewood to the boiler room, clean the boiler or remove the ashes every day. it can be argued that gas boiler or centralized district heating as a heat source are the most attractive regarding comfort, investment, and energy costs for the 10-year period. however, natural gas or district heating networks are not available in all areas. therefore, choosing a heat source for a building that cannot be connected to the natural gas or district heating networks and at the same time seeking to achieve comfort and ecological environment, a better choice would be to use “air to water” heat pump. the energy price of this system is higher and exceeds 0.036eur/kwh excluding installation. however, the investments in this system are lower by 50% compared to “soil to water” heat pump system. recommendations for the selection of the heat source for a residential building in a cold climate country are presented in fig. 2. *1-lowest, 7-highest 77 journal of sustainable architecture and civil engineering 2018/2/23 the figure shows quick evaluation of possible heating alternatives and gives qualitative and quantitative comparison of different types of heating. the efficiency of the heating system of the building (ηhs) is calculated evaluating possible manual and automatic regulation both of the heating source and heating system. it is noticeable that automatic regulation and additional equipment plays an important role in the whole system evaluation, because automatically regulated system with a solid fuel boiler and accumulation tank (ηhs=0.686) can be near to the condensing gas boiler without automatic regulation (ηhs=0.704). quantitative data for the grade evaluation of the heating system installation and exploitation costs is taken from table 8. grade “1” indicates the lowest cost level and grade “7” indicates the most expensive implement. analyzing the data presented in fig. 2 it should be noted that because of the rising economic situation in the country, increasing income and people business ones of the most important criteria for choosing the most suitable heating system is its reliability and efficiency. operating costs of the heating systems are not so important as it was 10 or 15 years ago. the data presented in this study reflects the current state of installation and operation of heating systems. it is assumed that the situation will change slightly in the future. looking at the prospect of 20-30 years, oil and its price will be a major and decisive factor in the global economic development. changes in oil prices will affect natural gas, energy for transport and other energy sources prices. the data presented in fig. 2 should be relevant in the future while selecting the heating system for residential buildings. due to good infrastructure, lithuanian consumers usually have many alternatives in choosing a heat source – from district heating to the gas boilers. many objective and subjective criteria should be taken into account in order to determine the most suitable heat source. the main criteria that should be evaluated are: installation and exploitation costs, daily maintenance needs, additional space for the equipment and the influence of selected heat source to the energy efficiency of the building. the lowest installation and fuel cost for the 10-year period can be reached by using solid fuel (firewood) boiler without accumulation tank (8566eur) if daily maintenance of the boiler is acceptable. when the infrastructure of gas supply network is available a condensing gas boiler with heat exchanger for domestic hot water can give minimal maintenance and space saving with 26,6% increase of total price (10849eur). higher primary installation cost (11800eur) for heat pump (type “soil to water”) does not guarantee the lowest total price for the 10-year period. since there are many options to combine the heat source for a building, additional analysis could be made to evaluate the cost of heat pump combined with solar panels etc. conclusions bosh j., johnson fx., mertens r., roubanis n., loesoenen p., gikas a., et al. panorama of energy: energy statistics to support eu politics and solutions. eurostat; 2008. černeckienė, j., vaičiūnas, j., valančius, r., jurelionis a., zdankus t. recent advancements in the use of on-site biomass systems in the build environment. current sustainable/renewable energy reports. 2018; 5(2) 156-162. directive 2010/31/eu of the european parliament and of the council of 19 may 2010 on the energy performance of buildings. available at: https://eurlex.europa.eu/legal-content/en/all/?uri=celex%3a32010l0031 [accessed 10 may 2018]. ehpa 2017. european heat pump market and statistics report 2017. available at: http://www.ehpa. org/about/news/article/european-heat-pumpmarket-and-statistics-report-2017-is-availablenow/ [accessed 6 may 2018]. eso 2017. tyrimas: kiek kainuoja namu siluma? available at: http://www.eso.lt/lt/ziniasklaida/tyrimas-kiek-kainuoja-namu-siluma.html [accessed 7 may 2018]. european commission 2011. com (2011) 112 final. commission communication. roadmap to a competitive low carbon economy in 2050; 2011. european commission 2018. available at: https:// ec.europa.eu/energy/en/topics/energy-efficiency/ buildings [accessed 2 may 2018]. european commission. draft horizon 2020 work programme 2014-2015 in the area of secure, clean and efficient energy; 2015. references journal of sustainable architecture and civil engineering 2018/2/23 78 galvonaitė a. et al. lietuvos hidrometeorologijos tarnybos prie aplinkos ministerijos klimatologijos skyrius: vidutinės klimatinių rodiklių reikšmės lietuvoje 1981–2010 m. (climate averages for lithuania 1981–2010) 2013. access via internet: http:// www.meteo.lt/documents/20181/103901/lietuvos_klimatas_09_25.pdf. honkapuro s., koreneff g. heat pumps and other der technologies in finland. iea dsm agreement. task xvii integration of dsm, dg, res and storages. workshop in sophia antipolis, france. 2011. available at: http://www.ieadsm.org/viewtask.aspx?id=16&task=17&sort=0 [accessed 10 may 2018]. lsta 2011. silumos vartotojo vadovas. pirmas priedas. available at: http://lsta.lt/files/leidiniai/ silumos_vartotojo_vadovas/silumos_vadovo_ priedas%20koreg.pdf [accessed 8 may 2018]. lsta 2018. lietuvos šilumos tiekėjų asociacija. vidutinė šilumos kaina gyventojams (po perskaičiavimų). available at: http://lsta.lt/lt/pages/apie-silumos-uki/silumos-kainos [accessed 25 april 2018]. regula 2017. valstybinė kainų ir energetikos kontrolės komisija. visuomeniniai tarifai ab “energijos skirtymo operatorius” nuo 2017 m. sausio 1 d. available at: https://www.regula.lt/elektra/puslapiai/tarifai/visuomeniniai-tarifai-ab-energijos-skirstymo-operatorius-nuo-2017-m--sausio-1-d.aspx [accessed 25 april 2018]. regula 2018. valstybinė kainų ir energetikos kontrolės komisija. gamtinių dujų arifai buitiniams vartotojams nuo 2018 m. liepos 1 d. [accessed 25 april 2018]. rsn 156-94. statybine klimatologija. vilnius: renkon; 1994. str 2.01.02:2016. pastatų energetinio naudingumo projektavimas ir sertifikavimas. available at: https:// www.e-tar.lt/portal/lt/legalact/2c182f10b6bf11e6aae49c0b9525cbbb [accessed 11 may 2018]. streimikiene d. residential energy consumption trends, main drivers and policies in lithuania. renewable and sustainable energy reviews. 2014; (35) 285-293. https://doi.org/10.1016/j.rser.2014.04.012 stuart js., bale v., reddy ma. rosen geothermal heat pump systems: status review and comparison with other heating options. applied energy. 2013; (101) 341–348. šilumos tiekimo ir vartojimo taisykles (en. rules for supply and consumption of thermal energy) order of energy minister of lithuanian republic. 2010, no. 1-297. jurgita cerneckiene lecturer kaunas university of technology, faculty of civil engineering and architecture main research area energy performance in buildings, hvac systems, renewable energy address studentu st. 48, lt-51367 kaunas, lithuania tel.+37061531533 e-mail: jurgita. cerneckiene@ktu.lt rokas valancius lecturer kaunas university of technology, faculty of civil engineering and architecture main research area renewable energy, indoor climate, energy performance in buildings address studentu st. 48, lt-51367 kaunas, lithuania tel. +37068010000 e-mail: rokas. valancius@ktu.lt laura stasiuliene lecturer kaunas university of technology, faculty of civil engineering and architecture main research area indoor air quality, thermal comfort, hvac systems, energy efficiency, building information modelling (bim) address studentu st. 48, lt-51367 kaunas, lithuania e-mail: laura. stasiuliene@ktu.lt eugenijus perednis senior research associate lithuanian energy institute, laboratory for renewable energy and energy efficiency main research area energy efficiency of buildings, usage of solar, wind and biomass energy address breslaujos str. 3, lt-44403 kaunas, lithuania e-mail: eugenijus. perednis@lei.lt juozas vaiciunas lecturer kaunas university of technology, faculty of civil engineering and architecture main research area waste water energy address studentu st. 48, lt-51367 kaunas, lithuania e-mail: juozas. vaiciunas@ktu.lt about the authors https://doi.org/10.1016/j.rser.2014.04.012 49 journal of sustainable architecture and civil engineering 2018/1/22 corresponding author: wahabak2002@yahoo.com characterization and effects of noise levels of portable generators used in residential buildings in ibadan metropolis, nigeria: a case study received 2018/03/07 accepted after revision 2018/06/18 journal of sustainable architecture and civil engineering vol. 1 / no. 22 / 2018 pp. 49-63 doi 10.5755/j01.sace.22.1.20175 © kaunas university of technology characterization and effects of noise levels of portable generators used in residential buildings in ibadan metropolis, nigeria: a case study jsace 1/22 http://dx.doi.org/10.5755/j01.sace.22.1.20175 akeem b. wahab department of building, faculty of environmental design and management, obafemi awolowo university, ile-ife, nigeria the proliferation of generators used in urban settlements in nigeria over the years has been a major source of concern to the health and comfort of building occupants. this study, therefore, assessed the impact of outdoor and indoor noise levels associated with the use of generators on the environment and building occupants. the study area, ibadan metropolis, was divided into core, transition and suburban zones. five (5) residential buildings were purposively selected in each of the core, transition and suburban zones of the study area. measurement of noise levels was taken with the use of a digital sound level meter with compliance to nesrea and osha standards. the outdoor noise levels before and during use of generators were taken at 0, 2 and 4m from external walls of the buildings sampled while the corresponding indoor noise levels were taken at the actively useable internal space; at a least distance of 1m from internal walls, 1.2 1.5m above floor level and 1.5m from windows. descriptive and inferential statistics were used to analyse the data collected. the findings of the study revealed that the mean indoor noise levels of 79.97 db, 87.4 db during use of generators in residential buildings were highest in the core zone and above the permissible limits. the study concluded that there should be adoption of best house-keeping practices by positioning generators in properly built enclosure features; and efforts made to enforce sales and procurement of generators with noise abatement mechanisms that can conform to iso 3744 and local codes so as to mitigate impact of its high noise levels on the health and comfort of building occupants. keywords: generators, impact, noise generation, off-grid power supply, standards. in spite of nigeria’s huge resource endowment in energy and enormous investment in the provision of energy infrastructure, the performance of power sector has remained poor in comparison with other developing economies. according to world bank (2005), nigeria had the highest percentage of system losses at 33 to 41% with the lowest generating capacity factor at 20%, the lowest average revenue at us dollars of 1.56 kwh, the lowest rate of return at 8%, and the longest average accounts receivable period of 15 months when compared with those of 20% of other developing countries. as a result of this fundamental problem, households, businesses and industrial premises rely on their self-procured electricity from generators that have attendant operating and capital costs (idiata et al., 2010; awofeso, 2011). introduction journal of sustainable architecture and civil engineering 2018/1/22 50 a constant power supply is a critical component of every successful modern business, and where power failure happens more often and takes more time to fix, a reliable standby generator is really essential to power all the equipment and systems (pabla, 2003; gross, 1986). today, the most common form of off-grid electricity supply are generators running on diesel or gasoline. generators are used not only by rural households but also by the grid-connected households and industries as a more stable supplement to the grid power. the rural incidence of diesel generator in nigeria is difficult to estimate, but 96 to 98% of the grid-connected firms are known for the ownership of private generators (tyler, 2002). the impacts of the various types of generators used by occupants of buildings are enormous on environmental quality and people’s health. this has elicited major concerns among environmentalists and other players in the built environment (obadote, 2009). the use of generators is very common in most parts of nigeria, and most small-scale businesses that would have been essentially noiseless produce heavy noise pollution from generators (akande and ologe, 2001). this has resulted in the exposure of building users to a number of hazards associated with the use of generators in buildings. common hazards are air, soil, noise and water pollution. these hazards do not only affect users of the generators but also affect people living in the neighbourhood. the main health risks, as identified by the world health organization (2004) include pain and hearing fatigue, hearing impairment including tinnitus, annoyance, interference with social behaviour (aggressiveness, protest and helplessness), sleep disturbance, cardiovascular effects and hormonal responses. the operation of generators is associated with noise generation. in nigeria, with the proliferation of generators in every nook and cranny, it becomes an issue that dependence on it as the only reliable source of power supply would create noise pollution. the common effects of noise pollution such as loss of hearing ability, headaches, interference with communication, nervousness, lack of concentration and insomnia and impairment of efficiency have all been identified and documented (shapiro, 1993; ebeniro et al. 1999; avwiri and nte, 2003; and ahmad and abubakar, 2012). egunjobi (1988) in his study of urban environmental pollution reported that noise had interference on speech and communication; and concluded that at about 85 db, people had to shout to be heard. nwaogozie and owate (2000) examined noise levels generated within the port harcourt refinery premises as being spatially well dispersed, and at the fenced boundaries, noise levels are well below fepa’s permissible limit of 90 db. the who and fepa respectively have noise limits set at 70-75 db and 90 db, and noise levels above these limits can cause health hazard to people in the environment. the transmission of noise into building spaces from installations like generators positioned outside may create indoor noise beyond limits approved by the who. researches related to the use of noise of generators in buildings were assessed. john et al., (2016) examined generators used in buildings in institutional settings. their findings showed that the mean noise level both indoor (60.26 db) and outdoor (58.15 db) respectively caused reported health problems like ear pains, headache and tiredness. according to senanayake (2002), children between the age of 2 to 5 years in sri lanka were exposed to 73-78 db and 70-73db of noise from generators in day and night time respectively. saber (2014) investigated noise pollution level in different environments in erbil city and showed that in 177 sites that were examined, the indoor and outdoor sound pressure level were 87 db and 105 db respectively and thus caused hearing impediments; salawu et al., (2015) carried out assessment and control of near-field noise levels of the 650 va power generator in a residential building in moro local government of kwara state, nigeria and found that such generating sets should be positioned at least 3 meters away from buildings in order to be safe for use; sellappan (2013) carried out a study on noise impacts associated with power generators used in construction activities of dct project and found that the noise levels produced by them were much higher than the permissible limit while peter (2013) investigated noise pollution in laboratory buildings and showed that noise from devices used in the laboratory that can lead to a variety of medical issues for the laboratory personnel can be reduced 51 journal of sustainable architecture and civil engineering 2018/1/22 by selecting systems that are specifically designed with noise reducing components. studies of akindele and adejumobi (2016); and osagie et al., (2018) on noise levels of generators in south southern part of nigeria found sound pressure level above the set limit. while trying to assess the use of generating sets and the likely impacts that it can have on the environment, few other studies have been carried out on generators used in buildings in nigeria and especially in the study area. studies of ana et al., (2014); stanley et al., (2011); komolafe (2011); sonibare et al., (2014) did not focus on the likely indoor and outdoor noise effects through comparison with established standards that are associated with the use of generators in residential buildings; hence the need for this study. thus, the aim of the study was to assess outdoor and indoor noise levels of generators used and its impact on the environment and building occupants. ibadan is an urban centre located in the humid southwest of nigeria which is the capital city of oyo state and is also one of the fastest growing cities in the country (ayeni, 1994). the study was carried out in ibadan metropolis, oyo state which is a significant geographical entity in southwestern nigeria (fig. 1). the study area is characterized by residential and other types of buildings with the use of generators by the occupants since the study was urban-based as ibadan was put in the category of a metropolitan urban centre according to the 2006 population centre. the geographical location of ibadan falls between coordinates 7o 22ꞌ 47ꞌꞌ north of the equator and 3o 53ꞌ 0ꞌꞌ east of the greenwich meridian. the entire area of ibadan is largely well-drained, though many of its rivers are seasonal. developed land increased from only 100 ha in 1830 to 12.5 km2 in 1931, 30 km2 in 1963, 112 km2 in 1973, 136 km2 in 1981 and 214 km2 in 1988 (mabogunje, 1968). it is therefore capable of reflecting practices and attributes of the region. its estimated population of 2,559,853 by the 2006 population census places the city in the category of a metropolitan urban centre (fgn, 2009). the study concentrated on the five local government areas that made up ibadan metropolis namely: ibadan north, ibadan north east, ibadan north west, ibadan south east and ibadan south west. the local governments have a population of 1,343,147 (fgn, 2009) and the other six local governments that made up ibadan land were left out. the choice of the local governments was due to the fact that the research is urban-based and focused on the sustainability of generating sets used by residents/occupants of buildings that were within the metropolis of the study area. study area fig. 1 map of the study area, ibadan metropolis. source: ibadan google map (2016) was due to the fact that the research is urban-based and focused on the sustainability of generating sets used by residents/occupants of buildings that were within the metropolis of the study area. figure 1: map of the study area, ibadan metropolis source: ibadan google map (2016) research methodology the sample frame for the study was made up of residential buildings that existed in the selected five local governments of ibadan metropolis occupied for residential purposes and where generating sets were used. a reconnaissance survey was carried out to get preliminary information on the types of generators used by the respondents and the most commonly used type were of the rating 0.6 kva to 3.8 kva, and thus selected for the study. the preliminary information obtained also included characteristics of generators used by the respondents in the study area. the study area was divided into a list of different residential/political wards determined and used for the purpose of the 2011 general elections by the (oyo state independent electoral commission, 2013). the multi-stage sampling technique was employed for the study. the first stage involved delineation of residential areas in ibadan metropolis into different zones based on age and other criteria. the technique of delineating residential areas in nigeria involves the use of historical and physical attributes. it takes into consideration, a period of the emergence of a city or a section of a city, housing characteristics, environmental qualities and population per square kilometre (density) among others (afon, 2008; wojuade, 2012; adigun 2013). faniran (2012) among other authors had identified three (3) residential zones in ibadan. these are: core, transition and suburban residential zones and were thus adopted for this study. the stratification made the heterogeneous nature of the study population to be reduced into residential/political wards of similar and homogeneous features. journal of sustainable architecture and civil engineering 2018/1/22 52 the sample frame for the study was made up of residential buildings that existed in the selected five local governments of ibadan metropolis occupied for residential purposes and where generating sets were used. a reconnaissance survey was carried out to get preliminary information on the types of generators used by the respondents and the most commonly used type were of the rating 0.6 kva to 3.8 kva, and thus selected for the study. the preliminary information obtained also included characteristics of generators used by the respondents in the study area. the study area was divided into a list of different residential/political wards determined and used for the purpose of the 2011 general elections by the (oyo state independent electoral commission, 2013). the multi-stage sampling technique was employed for the study. the first stage involved delineation of residential areas in ibadan metropolis into different zones based on age and other criteria. the technique of delineating residential areas in nigeria involves the use of historical and physical attributes. it takes into consideration, a period of the emergence of a city or a section of a city, housing characteristics, environmental qualities and population per square kilometre (density) among others (afon, 2008; wojuade, 2012; adigun 2013). faniran (2012) among other authors had identified three (3) residential zones in ibadan. these are: core, transition and suburban residential zones and were thus adopted for this study. the stratification made the heterogeneous nature of the study population to be reduced into residential/political wards of similar and homogeneous features. research methodology methods of measurement measurement of outdoor noise level five (5) houses were purposively selected in each residential density of the local governments in the study area for the measurement of noise level because of the seemingly restriction of the researcher to have access into buildings. this indicates selection of twenty-five (25) residential buildings in each zone and a total of seventy-five (75) residential buildings in the entire study area respectively. a gm1351 digital sound level meter was used to take noise levels. it measures noise between 30-130 db, has an accuracy of 1.5 db, frequency range of 31.5 hz to 8.5 khz and resolution of 0.1 db. each measurement was carried out before and during the use of the generating sets both outdoor and indoor (actively useable internal space) of the selected residential buildings. the digital sound meter was positioned at the working platform, at about 1.2-1.5 metres above ground level. measurements of noise levels in the selected buildings were carried out before and during the use of the generators both indoor and at distances outdoor. thus, noise measurements of the generators were taken to assess its contributory impact/effect on the environment and users of the buildings sampled. in order to assess contributory effect and impact of the use of generating sets on the outdoor noise in the study area, three (3) measurements of outdoor noise level before and during the use of generators were taken at three points; 0, 2 and 4 m respectively from the external walls of residential buildings sampled in the study area and the mean values of the measurements were determined. 0 m was the point of location of the generator by the external walls of the buildings sampled. in order to also assess contributory effect and impact of the use of generating sets on the indoor noise level in the buildings, three (3) measurements of indoor noise before and during the use of generators were taken in an actively used internal space in the residential buildings selected and the mean values of the readings were determined. the measurements were taken at a least distance of 1m from internal walls or other major reflecting surfaces, 1.2 -1.5m above floor level and 1.5m from windows of the buildings. clips of fig. 2 show the gm1351 digital sound level meter that was used to take noise levels in the study area, the measurement of noise levels either before or during use of generators in sections of the buildings where the measurements were taken; while clips of fig. 3 show the sections of generators used for the study, diagrammatic representation of the measurement of the indoor noise in an actively used internal space of the residential buildings selected and the measurement 53 journal of sustainable architecture and civil engineering 2018/1/22 of the outdoor noise at 0, 2 and 4m respectively from the point of positioning of the generators in the study area (beside external wall of the buildings sampled). thus, descriptive and inferential statistical techniques such as frequency distribution, analysis of variance, t-test and trend analysis were used to analyse the mean values of the noise levels of the generators taken and also compared with the permissible limits of who and nesrea. fig. 2 clips of sections of the gm1351 used for the measurement of noise levels fig. 3 clips of sections of generators sampled and diagrammatic representation of the measurement of noise levels indoor and outdoor buildings where the measurements were taken; while clips of figure 3 show the sections of generators used for the study, diagrammatic representation of the measurement of the indoor noise in an actively used internal space of the residential buildings selected and the measurement of the outdoor noise at 0, 2 and 4m respectively from the point of positioning of the generators in the study area (beside external wall of the buildings sampled). thus, descriptive and inferential statistical techniques such as frequency distribution, analysis of variance, t-test and trend analysis were used to analyse the mean values of the noise levels of the generators taken and also compared with the permissible limits of who and nesrea. figure 2: clips of sections of the gm1351 used for the measurement of noise levels buildings where the measurements were taken; while clips of figure 3 show the sections of generators used for the study, diagrammatic representation of the measurement of the indoor noise in an actively used internal space of the residential buildings selected and the measurement of the outdoor noise at 0, 2 and 4m respectively from the point of positioning of the generators in the study area (beside external wall of the buildings sampled). thus, descriptive and inferential statistical techniques such as frequency distribution, analysis of variance, t-test and trend analysis were used to analyse the mean values of the noise levels of the generators taken and also compared with the permissible limits of who and nesrea. figure 2: clips of sections of the gm1351 used for the measurement of noise levels buildings where the measurements were taken; while clips of figure 3 show the sections of generators used for the study, diagrammatic representation of the measurement of the indoor noise in an actively used internal space of the residential buildings selected and the measurement of the outdoor noise at 0, 2 and 4m respectively from the point of positioning of the generators in the study area (beside external wall of the buildings sampled). thus, descriptive and inferential statistical techniques such as frequency distribution, analysis of variance, t-test and trend analysis were used to analyse the mean values of the noise levels of the generators taken and also compared with the permissible limits of who and nesrea. figure 2: clips of sections of the gm1351 used for the measurement of noise levels indoor measurement of noise outdoor measurement of noise figure 3: clips of sections of generators sampled and diagrammatic representation of the measurement of noise levels indoor and outdoor results and discussions preliminary information on the characteristics of generators the preliminary information depicting the characteristics of the generators sampled for the measurement of noise levels in the study area obtained during the reconnaissance survey involved their years of use (age), ratings, type, cost and brand respectively. it was found that across residential buildings of the study 4m 2m point of positioning of generator (0m) measuring device legend: generator building measuring device measuring device legend: indoor measurement of noise outdoor measurement of noise figure 3: clips of sections of generators sampled and diagrammatic representation of the measurement of noise levels indoor and outdoor results and discussions preliminary information on the characteristics of generators the preliminary information depicting the characteristics of the generators sampled for the measurement of noise levels in the study area obtained during the reconnaissance survey involved their years of use (age), ratings, type, cost and brand respectively. it was found that across residential buildings of the study 4m 2m point of positioning of generator (0m) measuring device legend: generator building measuring device measuring device legend: indoor measurement of noise outdoor measurement of noise figure 3: clips of sections of generators sampled and diagrammatic representation of the measurement of noise levels indoor and outdoor results and discussions preliminary information on the characteristics of generators the preliminary information depicting the characteristics of the generators sampled for the measurement of noise levels in the study area obtained during the reconnaissance survey involved their years of use (age), ratings, type, cost and brand respectively. it was found that across residential buildings of the study area, 45.82% of the respondents had been using their generators for 3 years, 25.88% (2 years), 14.82% (1 year) and 6.74% (4 years); the rating limits of generators selected for the 4m 2m point of positioning of generator (0m) measuring device legend: generator building measuring device measuring device legend: journal of sustainable architecture and civil engineering 2018/1/22 54 preliminary information on the characteristics of generators the preliminary information depicting the characteristics of the generators sampled for the measurement of noise levels in the study area obtained during the reconnaissance survey involved their years of use (age), ratings, type, cost and brand respectively. it was found that across residential buildings of the study area, 45.82% of the respondents had been using their generators for 3 years, 25.88% (2 years), 14.82% (1 year) and 6.74% (4 years); the rating limits of generators selected for the measurement was 0.6 – 3.8 kva due to the types commonly procured which largely depended on the petrol as their fuel. a large proportion of respondents in the residential buildings across zones of the study area (35.95%) spent between n1,100 – n3,000 monthly in fuelling the generators sampled while different brands of generating sets sampled were used by the respondents across zones of the study area. elemax brand of generator was largely used by the respondents 78(20.42%) and followed by 65(17.01%) that used tiger brand of generator. past studies of ahmad and abubakar (2012); fgn (2014) and noi polls (2015) also indicated that generating sets used would have different operating characteristics in terms of types, brand and cost of its fuel which would be borne by the users. outdoor noise levels of generators in the residential buildings the measurements of outdoor noise levels before and during use of generators in the residential buildings sampled across zones of the study area shown in tables 1 to 3 indicated that irrespective of the zone where residential buildings sampled were located, outdoor noise levels before the use of generators maintained a transit pattern of fluctuation in its readings at different points of measurements. this could be due to the dynamics of sound waves which can increase or decrease at any point of measurement based on the rate at which momentary air was set in motion. tables 1 to 3 also showed that at the point of positioning of generators, by the external wall (0m), outdoor noise levels in residential buildings in the core zone were comparably highest during use of generators (102.7 db) than the values taken in other zones and lowest in the transition zone (102.2 db). however, at 2 and 4 m points of measurement from locations of generators during its use by the external walls of buildings, outdoor noise levels in the suburban zone fluctuated between ranges of 71.1 79.2 db and 68.3 – 74.6 db respectively. this was found to be related to the types of house-keeping practice adopted and level of compliance with physical planning laws by the respondents. similarly, the outdoor noise measurements were significantly highest at the reference point, external wall of buildings (0 m) and lowest at the 4 m distance of positioning from the external walls of buildings. this could be due to the reduction in the pressure of the noise generated from the external walls where the generating sets were positioned (tables 1 to 3). the degree of variation of outdoor noise levels taken in the sampled residential buildings indicated that the mean levels of outdoor noise before or during use of generators were comparably highest in residential buildings in the core zone (52.34 db, 98.47 db). it was also found during the study that the type of generating set enclosure provided by the occupants of residential buildings in the core zone which affected their house-keeping practices informed the significantly high levels of outdoor noise measured during the use of generators in the core zone. the background noise varied disproportionately in buildings across the zones with the core zone having 47.3 63.5 db. results of the outdoor noise levels obtained from the noise measurement were also supported by findings of past studies of stanley et al., (2016) which got 85.13 db for the outdoor noise; john et al., (2016); akindele and adejumobi (2016) and osagie et al., (2018) which got comparably higher levels of noise than the permissible limits during the use of generators. trend analysis carried out on the rate of change of outdoor noise measurements in the residential buildings sampled during use of generating sets indicated that the percentage decrease in the values of outdoor noise measured from the external walls of buildings to the 2 m point of mearesults and discussions 55 journal of sustainable architecture and civil engineering 2018/1/22 surement was 18.57%. it further indicated that there was 4.33% decrease from 2 to 4 m points of measurement and 22.09% decrease was found at the 4 m point of measurement from the points of the positioning of generators (0m), by external walls of the residential buildings. outdoor noise level (db) before and during use of generators at different points l.g.a residential buildings 0m 2m 4m before use (db) during use (db) before use (db) during use (db) before use (db) during use (db) ibn 1 56.3 101.3 55.9 83.1 55.2 78.3 2 53.1 99.2 52.8 84.2 51.9 79.2 3 59.3 87.3 60.4 79.3 58.3 77.3 4 49.7 91.3 49.5 82.3 49.3 74.7 5 53.1 102.1 53.0 84.2 51.6 76.2 ibne 6 48.7 98.3 47.9 81.3 47.8 75.3 7 63.4 103.4 64.5 86.4 63.6 78.4 8 52.1 97.1 51.8 80.2 50.9 72.2 9 48.3 92.4 48.0 77.4 49.8 75.2 10 48.1 99.3 47.8 81.3 47.3 71.4 ibnw 11 51.4 102.7 49.3 82.5 49.2 76.5 12 53.1 102.5 52.7 83.1 52.3 75.1 13 49.9 97.8 49.9 84.8 48.5 75.8 14 63.5 99.3 62.8 80.2 61.7 72.2 15 52.1 102.1 48.8 83.3 48.1 74.3 ibse 16 48.3 97.8 47.9 86.8 47.7 82.8 17 63.5 99.2 63.1 84.2 62.8 75.2 18 48.2 98.3 47.9 83.7 47.3 77.1 19 49.3 93.6 48.7 79.6 48.4 76.3 20 48.5 96.5 48.3 78.8 48.8 69.8 ibsw 21 52.3 101.2 51.1 84.2 50.9 78.7 22 50.3 102.3 50.1 81.3 49.7 73.3 23 48.7 99.6 51.2 83.8 47.2 77.8 24 47.3 94.8 48.5 82.7 48.1 73.5 25 50.1 102.3 52.3 86.3 50.6 78.6 table 1 outdoor noise levels before and during use of generators in residential buildings in the core zone * 0 m = point of measurement from external wall of building l.g.a. local government area, ibn: ibadan north, ibne: ibadan north east ibnw: ibadan north west, ibse: ibadan south east, ibsw: ibadan south west journal of sustainable architecture and civil engineering 2018/1/22 56 table 2 outdoor noise level before and during use of generators in residential buildings in the transition zone outdoor noise level (db) before and during use of generators at different points l.g.a. residential buildings 0m 2m 4m before use (db) during use (db) before use (db) during use (db) before use (db) during use (db) ibn 1 46.3 99.3 46.0 83.7 46.1 77.1 2 45.7 93.6 45.3 75.6 45.3 72.7 3 48.3 97.4 47.9 79.4 47.6 73.3 4 46.7 99.3 47.1 83.3 46.4 78.2 5 47.6 97.2 47.2 82.5 46.8 76.0 ibne 6 48.3 100.3 48.0 79.6 48.0 71.1 7 46.1 93.7 46.1 78.3 45.9 72.3 8 45.2 97.3 45.0 79.1 45.0 73.2 9 46.3 98.3 46.2 79.6 45.7 72.4 10 48.3 100.2 48.3 78.0 48.1 71.3 ibnw 11 50.3 101.3 49.6 82.3 49.6 75.1 12 49.2 102.2 50.3 83.7 50.3 74.7 13 46.3 99.6 45.9 78.1 45.1 73.3 14 45.7 90.3 45.8 77.8 45.3 72.6 15 46.2 97.2 45.6 76.3 45.1 71.8 ibse 16 45.3 96.3 45.9 75.2 45.2 72.3 17 42.5 93.2 44.1 72.9 43.7 71.1 18 40.3 91.5 40.0 73.7 40.0 72.2 19 43.6 98.7 43.2 76.6 43.1 74.5 20 42.5 99.3 42.5 77.3 41.9 72.3 ibsw 21 45.3 101.2 45.1 79.1 45.1 75.2 22 43.2 97.2 44.2 76.3 43.1 70.3 23 42.1 98.3 41.8 81.2 42.0 75.5 24 43.4 98.6 43.7 79.0 43.1 72.4 25 42.1 93.5 42.0 70.8 41.8 68.3 * 0 m = point of measurement from external wall of building 57 journal of sustainable architecture and civil engineering 2018/1/22 table 3 outdoor noise level before and during use of generators in residential buildings in the suburban zone outdoor noise level (db) before and during use of generators at different points l.g.a. residential buildings 0m 2m 4m before use (db) during use (db) before use (db) during use (db) before use (db) during use (db) ibn 1 41.2 93.7 41.1 71.1 42.5 68.3 2 42.5 96.3 41.3 74.2 41.1 71.0 3 43.7 98.3 44.5 75.2 44.2 71.2 4 45.2 99.3 44.8 76.0 43.7 72.4 5 44.7 98.3 44.6 72.2 45.2 69.3 ibne 6 46.3 100.2 45.8 71.8 45.8 70.1 7 43.6 101.2 44.2 72.3 42.9 69.6 8 47.2 97.8 46.9 75.2 45.8 73.2 9 42.3 96.8 42.0 77.3 42.0 74.4 10 45.3 99.2 45.3 73.6 44.8 71.3 ibnw 11 44.3 98.7 44.1 76.4 43.7 74.2 12 46.2 97.6 46.7 72.3 45.8 69.8 13 43.2 98.5 43.0 79.2 43.0 74.1 14 42.7 96.3 42.4 76.5 42.3 73.3 15 44.3 98.1 45.1 76.1 43.8 72.2 ibse 16 46.2 99.2 46.0 78.3 45.9 74.6 17 43.1 88.1 43.1 73.0 42.7 68.9 18 42.3 97.6 42.0 76.1 42.0 73.5 19 46.2 98.3 45.8 77.2 45.2 73.1 20 44.5 99.2 42.3 75.1 42.0 71.2 ibsw 21 46.5 102.3 46.7 77.0 45.8 73.4 22 43.1 98.3 43.1 79.2 43.0 70.6 23 46.2 100.1 46.1 75.1 45.9 70.3 24 45.3 99.3 45.3 74.8 45.0 67.0 25 45.6 98.3 45.4 73.3 45.3 75.5 * 0 m = point of measurement from external wall of building journal of sustainable architecture and civil engineering 2018/1/22 58 indoor noise levels of generators in the residential buildings table 4 showed that prior to the use of generators in residential buildings, indoor noise levels were comparably lowest (42.3 db) in buildings in the suburban zone and highest in buildings (44.2 db) in the core zone. during the use of generators, the indoor noise level was least in the suburban zone (66.2 db) and also highest in the core zone (79.7 db). this was discovered to be due to the distances of the positioning of generators, house-keeping practices adopted, typology of buildings and profile of the respondents in the buildings sampled. the mean deviation of indoor noise levels before use of generators (50.34 db, 47.91 db) and during use of generators (70.20 db, 65.18 db) were obtained in core and suburban zone respectively. results of the indoor noise levels obtained from the noise measurement were also supported by findings of past studies of john et al., (2016) and stanley et al., (2016) which got 60.26 db 74 db respectively for the indoor noise due to the use of generating sets which were comparably higher than the permissible limits set by statutory bodies like who. thus, diagrammatic representation of the mean values of noise character/spectra in different zones of the study area on the outdoor and indoor noise levels in various places of the study area are shown in fig. 3 and 4 respectively. trend analysis showed the likely differences in the rate of change of indoor noise levels before and during the use of generators in the residential buildings sampled. the analysis showed that the percentage increase in the values of indoor noise in residential buildings in the core, transition and suburban zone before and during use of generator was 39.90%, 36.09% and 32.10% respectively. fig. 3 mean outdoor noise levels before and during use of generators in zones of the study area fig. 4 mean indoor noise levels before and during use of generators in zones of the study area core zone. during the use of generators, the indoor noise level was least in the suburban zone (66.2 db) and also highest in the core zone (79.7 db). this was discovered to be due to the distances of the positioning of generators, house-keeping practices adopted, typology of buildings and profile of the respondents in the buildings sampled. the mean deviation of indoor noise levels before use of generators (50.34 db, 47.91 db) and during use of generators (70.20 db, 65.18 db) were obtained in core and suburban zone respectively. results of the indoor noise levels obtained from the noise measurement were also supported by findings of past studies of john et al., (2016) and stanley et al., (2016) which got 60.26 db 74 db respectively for the indoor noise due to the use of generating sets which were comparably higher than the permissible limits set by statutory bodies like who. thus, diagrammatic representation of the mean values of noise character/spectra in different zones of the study area on the outdoor and indoor noise levels in various places of the study area are shown in figures 3 and 4 respectively. figure 3: mean outdoor noise levels before and during use of generators in zones of the study area figure 4: mean indoor noise levels before and during use of generators in zones of the study area 0 10 20 30 40 50 60 70 core transition suburban 50.34 47.91 47.91 70.20 65.18 65.18 (db) zo ne indoor noise during use indoor noise before use 0 20 40 60 80 100 core transition suburban 52.34 45.47 44.46 98.47 97.40 98.04 (db) zo ne outdoor noise during use outdoor noise before use core zone. during the use of generators, the indoor noise level was least in the suburban zone (66.2 db) and also highest in the core zone (79.7 db). this was discovered to be due to the distances of the positioning of generators, house-keeping practices adopted, typology of buildings and profile of the respondents in the buildings sampled. the mean deviation of indoor noise levels before use of generators (50.34 db, 47.91 db) and during use of generators (70.20 db, 65.18 db) were obtained in core and suburban zone respectively. results of the indoor noise levels obtained from the noise measurement were also supported by findings of past studies of john et al., (2016) and stanley et al., (2016) which got 60.26 db 74 db respectively for the indoor noise due to the use of generating sets which were comparably higher than the permissible limits set by statutory bodies like who. thus, diagrammatic representation of the mean values of noise character/spectra in different zones of the study area on the outdoor and indoor noise levels in various places of the study area are shown in figures 3 and 4 respectively. figure 3: mean outdoor noise levels before and during use of generators in zones of the study area figure 4: mean indoor noise levels before and during use of generators in zones of the study area 0 10 20 30 40 50 60 70 core transition suburban 50.34 47.91 47.91 70.20 65.18 65.18 (db) zo ne indoor noise during use indoor noise before use 0 20 40 60 80 100 core transition suburban 52.34 45.47 44.46 98.47 97.40 98.04 (db) zo ne outdoor noise during use outdoor noise before use 59 journal of sustainable architecture and civil engineering 2018/1/22 table 4 indoor noise levels before and during use of generators in residential buildings l.g.a bldgs. core zone transition zone suburban zone before use (db) during use (db) before use (db) during use (db) before use (db) during use (db) ibn 1 47.2 68.7 48.5 67.6 42.3 61.2 2 49.3 69.5 49.3 62.4 45.2 63.4 3 50.1 71.3 47.4 61.5 43.2 58.2 4 48.2 65.6 50.3 68.1 45.8 66.2 5 51.3 72.1 45.9 67.5 47.2 62.1 ibne 6 48.6 69.6 51.2 67.6 43.5 55.7 7 49.7 69.3 50.5 68.3 46.2 60.1 8 51.2 72.2 48.2 63.7 49.1 64.3 9 47.6 65.0 47.3 62.5 47.2 64.7 10 44.2 69.9 51.3 73.2 45.1 60.0 ibnw 11 60.8 72.5 53.6 75.3 48.2 63.2 12 66.2 78.2 49.2 69.1 43.7 53.4 13 49.3 69.3 50.3 72.6 46.3 60.7 14 48.5 66.5 46.3 65.7 45.1 62.4 15 53.7 79.7 48.2 63.1 46.2 56.2 ibse 16 49.6 69.3 47.3 65.2 48.2 63.8 17 51.3 72.0 46.2 60.2 45.2 60.3 18 47.6 65.3 43.1 61.3 49.6 55.4 19 48.3 69.7 47.2 62.1 45.5 62.3 20 47.6 68.3 48.7 63.6 46.7 60.1 ibsw 21 50.4 69.6 43.5 62.5 42.3 51.2 22 48.2 71.3 46.2 62.7 43.7 58.4 23 51.3 73.5 45.3 61.2 47.2 63.2 24 49.7 68.2 47.6 60.3 45.3 61.5 25 48.6 67.5 45.2 62.4 46.7 63.4 it further indicated that in all the residential buildings sampled in the study area, the percentage increase in the values of indoor noise before and during use of generators was 36.03%. this indicates the range of percentage increase of indoor noise levels that the occupants of residential buildings in the study area could be exposed to. journal of sustainable architecture and civil engineering 2018/1/22 60 comparison of noise levels in buildings sampled with the statutory limits the study assessed the impact of the use of generators in the study area by comparing values of noise measured both outdoor and indoor, before and during the use of generators in residential buildings in the study area. one sample t-test statistical technique was used to analyse contributory effect of generators through the level of deviation of noise before and during use from the limits set by who (2000)/nesrea (2009) in residential buildings. the result of the analysis as contained in table 5 showed that in the residential buildings, the t-test indicated that there table 5 comparison of noise levels in the residential buildings sampled with the who standards comparison of outdoor noise levels in the residential buildings one –sample test test value = 50 variables t df sig (2-tailed) mean difference 95% confidence interval of the difference lower upper outdoor noise before use -4.597 74 .000 -2.57200 -3.6869 -1.4571 outdoor noise during use 123.310 74 .000 47.97067 47.2079 48.7334 one-sample statistics n mean std. deviation std. error mean outdoor noise before use 75 47.4280 4.84558 .55952 outdoor noise during use 75 97.9707 3.31527 .38281 test value of who(2000) = 50db comparison of indoor noise levels in the residential buildings one –sample test test value = 35 variables t df sig (2-tailed) mean difference 95% confidence interval of the difference lower upper indoor noise before use 34.712 74 .000 13.72133 12.9337 14.5090 indoor noise during use 60.300 74 .000 31.86133 30.8085 32.9142 one-sample statistics n mean std. deviation std. error mean indoor noise before use 75 48.7213 3.42330 .39529 indoor noise during use 75 66.8613 4.57590 .52838 test value of who (2000) = 35db 61 journal of sustainable architecture and civil engineering 2018/1/22 conclusion and recommendations was significant difference in the outdoor noise levels measured and the who (2000)/nesrea (2009) standards; (test value = 50 db) at 0.001 level of significance. the mean values of outdoor noise before use and during use were 47.43 db and 97.97 db respectively and the corresponding mean differences from the 50 db set standards were -2.57 db and 47.97 db, before and during use of generators respectively. this indicated that noise impact due to the use of generators on the environment during its use could cause environmental pollution; affect the comfort of occupants and also subject them to hearing-related problems. it was further shown that at 95% confidence interval, the upper difference between the noise limit set by the who (2000) and the values measured was -1.46 and 48.73 respectively before and during use of generators. the relationship of the comparison is t = -4.597, p < 0.001 –before use; and t = 123.310, p < 0.001 –during use. the exposure of building occupants to the hazards and environmental imbalance as found in this study were similar to past works of akande and ologe (2001), world health organization (2004) and obadote (2009) on the associated effects of dependence on building services items. the one-sample t-test also indicated that mean values of indoor noise before and during usage were 48.72 db and 66.86 db (test value = 35 db), while mean difference in the indoor noise before and during usage were 13.72 db and 31.86 db respectively. it was further shown that at 95% confidence interval, the upper difference between the noise limit set by the who (2000) and the values of noise measured were 14.51 and 32.91, before and during use respectively (table 5). the results obtained from the analysis revealed that there was a significant difference in the outdoor noise level in residential buildings during the use of generators than the corresponding indoor noise levels during the use of generating sets. the relationship of the result is (t =34.712, p< 0.001-before use; and t = 60.300, p < 0.001during use for the indoor values). the results of the outdoor and indoor noise levels associated with the use of generators obtained showed anthropogenic implications of its use above limits set by statutory bodies. the findings of rao et al. (1988); nailong et al. (2008); fuller et al. (2012); paravathi and gopalakrishnan (2003) also showed that the use of generator set produced noise levels above permissible limits approved and it exposed the personnel to potential hazards. also, nailong et al. (2008); nwaogozie and owate (200); in their studies found that people can be exposed to noise from different activities that will cause pollution/environmental hazards and medical effects. the results obtained from the study established that outdoor and indoor measurements were highest in residential buildings in the core zone either before or during the use of generating sets. this was found to be directly related to the levels of compliance of the building occupants to the house-keeping practices, building typology, physical planning statute, and their socio-economic characteristics. reduced outdoor noise levels were measured at distance limits beyond 2 m from the external walls of buildings across zones of the study area during the use of generators. the study showed that there was a significant difference in the indoor noise level in the residential buildings sampled and the standards set by the world health organisation (who) and national environmental standards and regulations enforcement agency (nesrea). in view of the exposure of building occupants to noise level above standards set by regulatory bodies and dependence on generators as means of power supply in buildings, there is need to license sale of generating sets with noise abatement mechanisms and properly tested at the point of manufacturing so as to guarantee that their operational performance conform to iso 3744 and existing local codes. building occupants should also adopt best house-keeping practices by positioning them in properly built enclosure features (generator house) located away from external walls of their buildings so as to dampen noise generated. this will allow fair compliance with the ordinance of nesrea. journal of sustainable architecture and civil engineering 2018/1/22 62 references adigun, f.o., abolade, o. and akeju, e. death by breath: case of indoor air pollution in akure, nigeria. in issues in the built environment, afon a.o. and aina o.o (eds), obafemi awolowo university press, ile-ife, 2013; 81-100. afon, a.o. intra-urban variation in solid waste storage practice in nigerian traditional city: the case of ogbomoso. journal of the nigerian institute of town planners, 2008; xxi(1): 104-129. ahmad, m.t. and abubakar, h. economic implications of the use of generators as alternative energy source of energy in kano metropolis, nigeria. international journal of research in commerce, economics and management, 2012; 2(2). 28-33. akande, t.m., and ologe, f.r. awareness of commercial grinding machine operators in ilorin to noise-induced hearing loss. tropical journal of health sciences, 2001; 8(1): 28-31. akindele, o.a. and adejumobi, d.o. mitigating the use of electric generators: an operative model of distance and greening buffers. greener journal of science, engineering and technological research, 2016; 6(3): 70-77. https://doi.org/10.15580/gjsetr.2016.3.052416098 ana, g., olowolade, a.t., abimbola, a.f., ige, o. and nriagu, j.o. generator emissions profile and the lung function status of workers within selected small-scale business premises in ibadan, nigeria, global health perspectives, http://dx.doi. org/10.5645/ghp2014.02.003, 2014. aviviri, g.o. and nte, f.u. environmental sound quality of some selected flow stations in niger delta of nigeria. journal of applied science of environmental management, 2003; 7(2): 75-77. awofeso, n. generator diesel exhaust: a major hazard to health and the environment in nigeria. amer j respiratory critical care med, 2011; 183, 11437-1438. https://doi.org/10.1164/ajrccm.183.10.1437 ayeni, b. the metropolitan area of ibadan, its structure and growth, in: filani, m.o., akintola, f.o. and ikporukpo,c.o. 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indoor air quality in developing countries (ed.) carter et al, june 6-7, austin, tx 78712, 2011; 46-50. stanley, a.m., mbamali, i., and dadu, d.w. impact of electric power generators’ variables on noise-level generation in indoor building environments. international journal of the constructed environment, 2016; 8(1): 17-29. https://doi.org/10.18848/21548587/cgp/v08i01/17-29 tyler, g. public and private electricity provision as a barrier to manufacturing competitiveness: africa region findings, world bank, march, 2002; http://www. worldbank.org// afr/findings/english/find221.pdf wojuade, c.a. evaluation of accessibility to social and economic activities in ibadan, nigeria. unpublished ph.d thesis submitted to the department of urban and regional planning, obafemi awolowo university, ile-ife, nigeria, 2012. world bank. the environment matters, washington d.c., usa, pp.28-36, 2004. world bank. energy sector management assistance programme in nigeria: expanding access to rural infrastructure: issues and options for rural electrification, water supply and telecommunications, the international bank for reconstruction and development, washington d.c., usa, 2005. world health organization. guideline values for community noise in specific environment: ttrb session, an agenda for transportation noise, management policies in the united states, 10 january, washington dc, usa, 2000. about the author akeem b. wahab senior lecturer obafemi awolowo university faculty of environmental design and management department of building main research area building services, building management system and environmental sustainability address ile-ife, nigeria tel. +2348033713670 e-mail: wahabak2002@yahoo.com 39 journal of sustainable architecture and civil engineering 2017/1/18 corresponding author: tugsar@gmail.com review on high-rise housing projects in istanbul: toward a sustainable architecture received 2016/10/27 accepted after revision 2017/01/09 journal of sustainable architecture and civil engineering vol. 1 / no. 18 / 2017 pp. 39-49 doi 10.5755/j01.sace.18.1.16598 © kaunas university of technology review on high-rise housing projects in istanbul: toward a sustainable architecture jsace 1/18 http://dx.doi.org/10.5755/j01.sace.18.1.16598 tuba sarı istanbul technical university, faculty of architecture, 34437 beyoğlu/istanbul/turkey emerging with population growth and developing technology as a result of industrial revolution, rapid and unplanned process of urbanization has led to rapid depletion of natural resources in the physical and biological environment. in consequence of urbanization, lack of urban land and accordingly excessive rise of land prices has resulted in vertical construction. in the phases of design, construction, use and demolition, high-rise buildings, consuming much more energy than low-rise buildings, have led to significant changes in the city skyline. with the rise of vertically dense structuring in the world, highrise buildings have become more questionable and requested the answers of how the buildings can be designed to care of human needs. therefore, green building practices paying attention to ecological data have entered as an important parameter of vertically dense building design. green building designs, and its derivatives are among the images and discourses used as a marketing strategy for the vertically dense housing design. a significant part of construction projects in istanbul, claims that they place emphasis on the use of natural building materials and energy efficiency to associate themselves with sustainability discourses. for many segments of society, sustainability is transformed into a perception management gathering terms, such as green technology, renewable energy and smart building. in this respect, the paper aims to evaluate the development of high-rise buildings in istanbul on metrocity towers, sapphire and varyap meridian projects in the context of sustainability principles and practices. these projects describe three different processes and applications of sustainability. the main aim of the paper to discuss the efforts of transformation from solid structures to sustainable buildings based on various images and discourses related to high-rise building projects. keywords: discourse, images, solid, structures, sustainable. introduction high-rise buildings consuming much more energy than low-rise buildings in the phases of design, construction, use and demolition, with the number increasing day by day has led to significant changes in the city skyline. high-rise buildings have become re-questioned in perspective of sustainable urban and architecture, and it is seeking the answers to the questions of how these structures become more human by designers. in this context, the concept of sustainability has a great importance to benefit in the most efficient degree from high-rise buildings and to minimize the damage given natural environment. the first part of the paper deals with the urban adaptation process of high-rise buildings, discussing some challenges such as urban density, access problems to buildings, connections with public transportation and road network as well as high energy consumption of high-rises. the second part engages with the use of sustainable design principles in high-rise buildings (building components, design methods, land use, etc.) and journal of sustainable architecture and civil engineering 2017/1/18 40 impressions related to the process. the third part mentions sustainability certificate systems consisting of a variety of systems and procedures setting standards for design besides sustainable design principles and strategies concerning high-rise buildings. after discussing vertically dense building design and urban sustainability in istanbul, the paper evaluates the process on metrocity towers, sapphire and varyap meridian projects in the context of sustainability. metrocity was selected as one of the first high-rise mixed use projects in istanbul, reflecting the characteristics related to the early period of high-rise residences, due to its solid structure and height. sapphire, one of the highest towers in istanbul dominating the city skyline, was selected depending upon its sustainable building design approach, height and relations with the external environment. as the other project of fieldwork, varyap meridian represents a different approach to sustainable building design with its green building practices and certification systems. in this respect, the paper aims to discuss the transformation from solid structures to sustainable buildings based on various images and discourses related to high-rise building projects in istanbul. methods discussion in the scope of the research, three main high-rise projects reflecting different characteristics of sustainability have been selected. in choosing the projects, the convenience sampling method, developed by mugo fridah (2002) is used according to design principles of these high-rise housing projects such as metrocity, sapphire and varyap meridian tower that were built at different periods in istanbul’s construction history. firstly, the challenges concerning the urban adaptation process, design principles and certificate systems related to the practices of sustainability are discussed and the application process of design principles are observed on these high-rise building projects. in this context, the main purpose is to define varied approaches to the concept of sustainability. in addition, exclusive interviews with the designers of these projects about their high-rise building projects and their integration to urban environment in the framework of sustainable design decisions have been planned. these interviews consist of open ended questions interrogating the adaptation of the project with the urban texture and its effects on the urban environment as well as the application forms of sustainability principles according to the designers. the questions are separated into two different categories. one of them is general, searching the challenges related to the urban adaptation process of these high-rise projects, and the other is a more specific question changeable according to approaches of sustainability related to these projects. question 1: how do you explain the urban adaptation process of the project and its effects on the urban silhouette? question 2: how do you explain the concept of sustainability and high-rise buildings? in your project, which methods and design principles do you use related to sustainability? the challenges related to the urban adaptation process of high-rise buildings when considering the impact of urban towers on the natural environment, against providing advantages such as limited land use and potential high densities, high energy use is among the main disadvantages. while figuring out the urban integration process of a high-rise building project, it should be addressed that some issues such as land and energy use, access, transport, construction difficulties and technology, and should be considered whether the project is able to respond to the main questions of environmental nature and technique (firley, gimbal, 2011). the first challenge related to urban adaptation of high-rise buildings is urban density reflecting the impact of the surrounding towers. a high-rise building may be inadequate to cope with the rapid flow of people whether the building is located in the dense urban fabric, since an urban neighborhood has already reached its saturation point. on the other hand, the towers may have been located in developing regions and area disconnected and isolated from the urban context. 41 journal of sustainable architecture and civil engineering 2017/1/18 considering the flow of people and goods into the building, to solve the access problem into the tower should never be seen as a simple task. the closeness of primary entrance locations separated for visitors and users, with the back entrance locations used for all the logistic functions related to the building’s operation can be a problem (al-kodmany, 2015). also, the best way to guarantee effective access to a tower is interpreted as providing enough space to be able to handle maximum population facing the tower and its close environment. good access, while at the same time providing the well-functioning of the tower, ensures conducting daily operations effectively. as well as access, the connections with public transportation and the road network of a high-rise building must be impeccable to get approval both among its users and in the larger urban context. as another challenge related to the urban adaptation process, it is an undeniable truth that highrise buildings consume much more energy compared to low rise buildings per square meter. the newly developed strategies improving some specific features that facilitate entering of daylight and wind to a tower seek to reduce excessive energy consumption. use of sustainable design principles in high-rise buildings for a sustainable design in high-rise buildings, it is essential to consider several criteria such as land, mass form, height, orientation depending on the climate and landscape factors, the use of floor space, the organization of space, facade systems, vertical transportation systems, service systems, and the production of most accurate solution. in this part of research, the use of sustainable design principles in high-rise buildings (building components, design method, land use, etc.) and impressions related to the process are discussed in detail. in fact, the main reason that explains the emergence of high-rise construction is based on the principle of land use. in the context of sustainable land use and site selection, restricted land use is accepted as a positive environmental feature, reducing urban sprawl, costly transportation and car use, and that enables the effective use of long-term city infrastructure. as another design principle, the function is the most significant factor determining the design of floor plans. as a high-rise building can be designed as a residential, office, government, entertainment and hospital structure, it can be designed as a mixed-use building consisting of some of these functions. in this respect, multi-functional buildings can have different uses at different times despite mono-functional buildings such as office towers. while a mixed use building keeps different types of functions under the same roof, it has the potential of reducing energy consumption to a minimum level by recovering the existing energy inside the building. height is one of the main differences between high-rise buildings and low-rise buildings, but a more important issue is the consequences of the height on the structural design. a high-rise building should be designed considering the lateral wind loads, entrance of daylight, facade systems, circulation of the structure, slenderness ratio and the other aesthetical and technical principles (firley, gimbal, 2011). just beyond the technical evaluation, there is a direct aesthetical relationship in between the tower’s connection with the city and the structural design of the tower. while technical requirements having severe and heavy structures on the base of tower, the need of aesthetical connection with the city desires transparency and open spaces. in terms of core planning and vertical circulation, circulation between floors in high-rise buildings is usually carried out via elevators. as well as elevators, the main stairs and escape ladders form the vertical circulation system of high-rise buildings. moreover, an accurate core planning with the proper functioning of a vertical circulation system is essential for the effective operation of the building. the position of the service core is the most important factor in the design of a high-rise building. the service core not only has structural outcomes but also has influences on the thermal performance and appearance of the building (al-kodmany, 2015). in respect to bioclimatic design, in recent years, the design and development studies focusing on high-rise buildings have led to the emergence of a new building type called the bioclimatic skyscraper. design and development integrate other bioclimatic aspects into building design as well journal of sustainable architecture and civil engineering 2017/1/18 42 as the current ecological impacts: the most efficient use of rain and wind, life-cycle approach to use of building equipment and materials, and the development of inner life examples for users of high-rise buildings are some of them. the main issue is the integration with nature. all arrangements avoid traditional geometry and respond to the dynamics of wind direction, climate and solar orbit. in addition to integrating plants with buildings, use of the effect of the sun in the form of a building, benefiting from environmental wind both as a source of energy and a design input, bioclimatic skyscrapers reflect a life style adapting the principle of openness with transitional spaces, passage ways, sky courts and terraces (hamzah, yeang, 1994). planting and landscaping elements should be used not only for the ecological and aesthetical benefits but also for the coolness of the building. the plants absorb carbon dioxide and produce oxygen; thereby providing benefits to the building and its environment. in this respect, ken yeang (2000) mentions that more use of recycled and organic building materials can be focused on in order to increase the level of integration in between planting and a green building system in future projects. besides, most users desire to establish a more direct relationship with the external environment and to have windows that can be opened to allow fresh air into spaces. however, this request can be obtained with transitional spaces and intermediate spaces such as balconies, terraces, etc. as well, sky gardens and sky courts offer their users personal landscape areas where they can plant as the gardens in the sky, and provide them with an opportunity to create their own personal environment. on the other hand, these open and semi-open spaces provide natural ventilation of the building benefiting from the daylight and wind in the design process. high-rise buildings and sustainability certificate systems at the early stages of design process, sustainable high-rise buildings require a greater level of integration with the environment because they require coordination of complex, interdependent systems (ali, armstrong, 2008). in the framework of sustainability in high-rise buildings, it is known that there is a variety of systems and procedures setting standards for design. one of the best known systems in the world, developed in america, is leed (leadership in energy and environmental design). another is breeam (building research unit environmental assessment method) established in the united kingdom. switzerland’s minergi and australia’s green star are also some of these systems. all of these systems and standards tend to make the classification of building in harmony with many criteria such as the adaptation in urban fabric, energy consumption, carbon dioxide emission and use of local sources. most of them are the accreditation systems required to provide some basic principles related to sustainable building design (al-kodmany, 2015). although these standards accept the sustainability concept containing ecology, social structure and the economy, they do not contain the analyses for these parameters. for example, the leed targeting the construction sector gives users the green building certification in the frame of five main categories (selection of location, energy efficiency, water efficiency, building materials, and the quality of interior space and life). most leed indicators are based on end-user impact (aykan, 2014). these certification systems deal with the strategies of energy, water and material efficiency, use of recycled or renewable materials, smart building automation systems and sustainable facade technologies more than design decisions taken in the building formation. since they evaluate building and construction systems more than design decisions, they can be inadequate due to the lack of essential information related to building design (sev, 2009). therefore, with the sustainable building evaluation systems, sustainable architectural principles and strategies must be interpreted and applied in the most suitable way for a sustainable building design. high-rise housing design and urban sustainability in istanbul developmentalist discourse forming the political area at the 20th century changed places with sustainable development at the beginning of the 21st century. sustainability in urban area is interested in economic, ecological and social issues directing the decision-making process about the 43 journal of sustainable architecture and civil engineering 2017/1/18 future of the city. for a metropolis at the scale of istanbul, sustainability has become a national issue beyond the urban limits. while istanbul is being re-planned as a huge construction and consumption field, socio-ecological based criticism rising against this growth policy is becoming a legitimate concern with respect to urban sustainability. a significant number of construction projects in istanbul, associating themselves with sustainability discourse, emphasize the significance of energy efficiency and the use of natural building materials in the design of buildings. some of them have leed or similar international green building certifications. however, according to data published by ugbc (us green building corporation) in july 2013, only 94 of the 38,658 projects registered for the leed certification program worldwide are located in istanbul. it is inevitable to say that this number coincides with a relatively low proportion for a city on istanbul’s scale (aykan, 2014). in recent years, the concept of sustainability, supported by nongovernmental organizations and some parts of the society, is used as a marketing tool that decorates the promotional page for projects changing the urban fabric of istanbul. in this regard, the language of the urban policy is being reshaped in the context of sustainability. green building practices considering ecological data have entered vertically dense housing design as an important parameter. highrise buildings generally deal with technological approaches, energy conservation and other issues regarding only the ecological aspect of sustainability. however, sustainability is a multidimensional concept that should be dealt with on the physical and economic dimension both on urban scale and building scale. in this context, the difficulties high-rise buildings have caused in the urban area should be evaluated with all aspects of sustainability, and new strategies and approaches should be developed to solve these problems. sustainability for many segments of society, is transformed into a perception management assembling the terms such as green technology, renewable energy and smart building. according to laclau (2006), sustainability, due to its ambiguous definition and expanding boundaries, faces the danger of transformation to a concept defined as “empty show” involving everything but actually saying nothing. while sustainability aims to re-question economic, environmental and social issues in a holistic way, in time indicators become indistinct establishing links between reality and this ground. however, the concept of sustainability becomes overly inclusive and superficial beyond the expectation of uses of the principles of good design. gated communities, a common housing settlement in istanbul, promise for living in nature away from the crowded city, which seem to be one of the main discourses of marketing strategies. today, in the context of these marketing methods still in existence, forests, green areas, and artificial lakes located in residential areas are presented as a measure to increase the value and status of these habitats. promising for a life away from the chaos of the city, situated in nature, these settlements actually depend on the infrastructure of the city and shape the urban area according to their needs. recently, mixed-use (containing residential areas, shopping, and other functions) high-rise buildings isolated from the environment, reflect the struggle of the domestication of nature. many projects in istanbul use the simulation of nature as a design method, bosphorus city, a residential complex simulating the bosphorus with its own components special to the area, and viaport venezia, a housing project using artificial water channels imitating the venice, are some of these projects simulating real ones (candan, akbulut, 2014). defined by ghertner (2011), the green aesthetic approach, as a new shape of the urban presentation form, rather than a measure of the real impact of structure to the environment, is an evaluation related to how a city needs to appear in the context of an aesthetical image (fig.1). eco-friendly or ecological projects and cities no longer represent the concepts reflecting brand value. in this context, the housing projects described as eco-friendly in istanbul are put on the market; the housing projects asserted to produce their own power compete with each other with roof gardens and environmentalist discourse. the common ground of these projects is to define the ecological life independent from the urban geography around, confining it a private sphere. aykan (2014) draws attention to the need of redefining urban policies regarding the principles of sustainability. journal of sustainable architecture and civil engineering 2017/1/18 44 the basic steps to realize this goal are sorted as to identify sustainability on a local scale, to create sustainability indicators, to report sustainability, and to formulate a long-term participatory policy. to identify sustainability on a local scale, overreaching the mainstream consisting of economy, ecology and social structure, it is essential to approach sustainability on the basis of municipalities and to inquire as to which parameters have an effect on the sustainability in urban life. in this process, it can be beneficial to observe the description and applications of the institutions such as the un, eu and gri in the context of urban sustainability. as the second step, in the phase of creating sustainability indicators, in order to sustain urban facilities without causing damage to the natural resources and socio-economic structure of the city in the long term is possible with a multivariate risk analysis. to realize that, some indicators need to be developed with the aim of monitoring the performance of the city in the framework of economy, social structure and ecology. combining the data analyzed through indicators on the axis of sustainability and sharing an integrated report periodically with the city’s users have a place in the development of a participatory policy of sustainability. to create long term participatory policies on the basis of sustainability depends on a balance between economy, ecology and social structure. a sustainable istanbul means where a place practices listed in the framework of this approach are applied effectively. in the absence of these practices, the concept of sustainability cannot go beyond being a new urban slogan decorating the billboards. fig. 1 the image of bosphorus city istanbul (top) and viaport venezia (bottom) metrocity towers (1997-2003) metrocity (1997-2003), a mixed use project designed by the architects, doğan tekeli and sami sisa, is discussed especially for its reflecting the contemporary living standards of the new century. in addition to two residential towers, the project consists of one office tower and a linear shopping center. after the urban planning of büyükdere street as an international business center in 1980s, land values in the region have increased considerably. the mixed use, containing different functions within the same building, is preferred in high-rise building design not only for economic reasons but also for a sustainable urban environment. while a mixed-use high-rise building is seen as a more profitable investment by the land owners, it also keeps alive the urban life around of the building in respect to sustainability. thus, the function of a business center dominating the region is becoming secondary, the business district, living during the day and turning into the abandoned dead space at nights, can be alive all the time. results 45 journal of sustainable architecture and civil engineering 2017/1/18 due to its location on büyükdere street, metrocity towers easily connects to tem and e-5 freeways with the bosphorus and fatih sultan mehmet bridges. in addition, the most important advantage of metrocity towers is its integration directly to the urban system through the metro line. the towers are located in a dense urban fabric, on the axis of büyükdere-maslak, a primary business center in istanbul. in the sense of urban sustainability, environmental integration and its relationship with the external world on the ground floor while giving a direct connection to the subway network provides advantages in terms of access to the building (fig.2). also, public space in front of the towers, except for being an access area to the towers, is not completely supported with other functions such as commercial units, small playgrounds, other social facilities. the building’s facades in accordance with its architectural design are covered with cladding glass and aluminum fig. 2 metrocity towers’ silhouette, site plan and section drawings (yem, 2016) composite panels. in terms of the microclimate of the building, the only advantage is that the windows of the office tower in metrocity can open to fresh air contrary to some high-rise towers in which artificial ventilation is the only option. doğan tekeli, one of the designer architects of the metrocity towers, mentions that the towers with their proportions, facades, material and images display a behavior as a humanist of all high-rise buildings around büyükdere street. as büyükdere street is planned as a central business area, the architect says that the towers fit the urban fabric around them in terms of height and position in the city skyline (doğan tekeli, personal interview, 1 april 2016). istanbul sapphire (2006-2011) designed by tabanlıoğlu architecture, istanbul sapphire as a mixed use project, has a tower that brings recognizability to its surroundings with its 261-meter height in the urban fabric. the building is located on büyükdere street, one of the main arteries of a business center in istanbul, so it has direct connection to the subway, tem and e5 freeways, and the bosphorus, fsm bridges. the building, located in a dense urban fabric, has no direct link to büyükdere street, but from a neighboring side road and providing a direct link to the subway line, could be protected from vehicular traffic. from an external perspective, the form of the building tapers gently upwards. it benefits from natural light at a maximum level, with the help of a glass covering expanding from the fourth floor and transforming into eaves with a soft curl. by means of the transparent and permeable eaves, day-light can reach down to the basements. multi-layered and mobile, a large space perception is created in the bottom of these eaves where cafe, bars, restaurants and shops are located. journal of sustainable architecture and civil engineering 2017/1/18 46 in comparison with metrocity towers, it is possible to say that sapphire tower brings a connection with the external environment by this kind of eaves design on the ground floor. however, the tower has a lack of spatial connection with the close environment such as the other high-rise buildings in the region. in the presentation of the project, named the first ecological high-rise tower in turkey, it has emphasized its bio-climatic design principles as well as the height and location of the tower. to ensure energy efficiency, some design criteria have been used for active use of day light, and some details have been applied to save energy inside and outside the building. the facade of the tower consists of two shells independent from each other (fig.3). interior spaces are protected from bad weather conditions and sound with the help of an outer shell. this transparent shell allows comfortable spatial arrangements by creating a buffer zone between the inner and outer atmosphere. breathing by means of moving, restrainable vents, technical equipment and natural ventilation, sapphire tower is designed regarding consumption of less energy for the microclimate of the building more than other high-rises in the area. murat tabanlıoğlu, the architect of the tower, has described that the building rises in conformity with the surrounding high-rises and is still of nature-friendly facilities such as vertical gardens. in addition to the comfort provided by modern technology, istanbul sapphire has the infrastructure and the location that will ensure easy transportation possibilities. there are also residences of different sizes at different levels of the building. the building is planned as four separate housing zones, with a common zone between the sections containing indoor gardens, social areas, maintenance and support facilities, and the mechanical systems. also the architect emphasizes that environmentally friendly systems have been used to ensure low energy consumption (murat tabanlıoğlu, personal interview, 7 april 2016). in brief, the building is especially focused on the height and bio-climatic structure as the main features of the project. however, it must be underlined that the height of a building does not mean this building is designed better or superior to other structures. the height of building is used as an indicator of economic and symbolic power of the building. rather than the height of the building, the structure can be separated from other structures in accordance with the relationships established between the structure and its natural and artificial environment, so it belongs to the urban area. the new design trend in high-rise buildings in the world is related to being able to provide production of its own energy and to sustain its existence with minimum damage to the environment. varyap meridian (2009-2010) designed by rmjm, an american office in istanbul, varyap meridian is a mixed use highrise building project consisting of residential blocks, a hotel, and a business center, along with commercial and social areas. in the context of bio-climatic design, the blocks are equipped with facade materials in order to reduce the harmful effects and warmth of the sun to the lowest level. the fig. 3 istanbul sapphire tower, with section drawing and the image of interior garden (arkiv,2016) 47 journal of sustainable architecture and civil engineering 2017/1/18 facade reflects a hybrid system consisting of glass and ceramic panels (fig.4). while reducing cooling need by protecting interior space from overheating, these light colored windows ease the heating load by allowing a high level of sun light to enter inside, in the winter. the windows, which can be opened up to a certain floor, provide occupants the ability to take advantage of natural ventilation whenever they feel the need. the project, designed in accordance with leed criteria, integrates with renewable energy sources in addition to green building features. in order to reduce fossil fuel use and carbon dioxide emissions, solar panels and wind turbines are used so as to produce electricity in the project. with the strategies of the choice of ecological material and waste management, energy, water and heat savings up to % 40 are provided in the project. also, it works to minimize heat losses by positioning buildings according to solar and wind, to improve the insulation with the right material choices, to take maximum advantage of natural lighting, and to give place to plants consuming less water in landscaping. the main discourse of the project is that it will be the first and only high standard green housing project and it supports this idea with high-rise building certification systems and prizes. in brief, the common approaches, method and strategies related to the concept of sustainability in high-rise buildings are shaped with building facade systems energy efficiently, the integration of landscape elements to the building, the use of greenery even on the top floor, the use of renewable energy systems, solar control and the use of natural ventilation systems, and the design of building programs encouraging mixed-use. as can be seen from the specified common approaches and strategies, sustainability issues in high-rise buildings are discussed mostly at building scale. in fact, buildings create city, so it is not possible to consider building sustainability apart from urban sustainability. it must be evaluated in a holistic way. one of the major problems of high-rise buildings is the rupture of relations on the street level. in order to resolve the problems in the way of sustainability of high-rise buildings, besides use of renewable energy resources and supporting of mixed-use, placing some functions such as restaurants, shopping centers, social and commercial areas on the ground floor will be a highly effective solution to improve the relationships of high-rise buildings with the street. another necessity of sustainability of high-rises is that they should be designed being aware of how cities are affected by high-rises within the frame of urban sustainability. murat yılmaz, from dome+partners, an architectural company in turkey, who has cooperated with rmjm, emphasizes the importance of urban density related to the urban adaptation process of the varyap meridian project. the architect remarks that urban adaptation of the project depends on the necessity related to determination of specific densities previously in urban planning (murat yılmaz, personal interview, 15 april 2016). the lack of a planned density hierarchy results in some difficulties of seeking balance and adaptation in architecture. despite these challenges related to nonintegrated approach of urban planning in turkey, the architect states that varyap meridian towers are designed considering the relationships with the close environment on urban scale. however, the residence towers of varyap meridian are designed as gated communities in istanbul; the state of being an enclave causes the lack of a relationship with the urban environment. however, two different aspects, urban scale and building scale connecting with high-rises and sustainability in turkey can be discussed. in this context, the varyap meridian project is qualified for some green building certificate systems about sustainability rather than having a vision related to urban sustainability. in brief, high-rise buildings in istanbul do not seem to have been designed with an integrated sustainable approach related to urban planning. the development of vertical dense construction in the housing has triggered discussion of many issues such as high-rise and energy use, green-building relationship, climate, urban sustainability, infrastructure and transportation systems. green building practices regarding ecological data have entered as an important parameter to vertically dense housing design in istanbul. the sapphire tower and varyap meridian have applied the bioclimatic design principles such as the use of daylight, natural ventilation, materials for the energy-efficient façade design, and the use of conclusions journal of sustainable architecture and civil engineering 2017/1/18 48 spaces opening the nature such as vertical gardens, sky courts, and etc. the main problem of high-rises in istanbul is based on the integration with urban tissue. in terms of infrastructure and transportation systems, metrocity and sapphire towers provide directly link to urban transportation with subway lines and freeways around the buildings. while metrocity towers display the lack of open spaces for public use on the ground floor, sapphire tower establishes a connection with the external environment with eaves design on the ground floor. many high-rise projects engage with the issues such as energy conservation adopting a technological approach related to ecological sustainability. and, they apply mostly high-rise building certification systems as seen in varyap meridian project. however, sustainability is a multidimensional concept that should be dealt with to the social, physical and economic extents both on urban and building scales. it is not possible to consider building sustainability apart from urban sustainability. in this context, the problems that high-rise buildings have created in the city are well understood and new strategies and approaches should be adopted to solve these problems in respect to all aspects of sustainability. today, sustainability for many segments of society is transformed into a perception management assembling the terms such as green technology, renewable energy and smart building. for metropolises on the scale of istanbul, it is unavoidable that every project changing the urban texture has long-term effects overflowing out of the city. such a process requires to prepare of urban sustainability reports in a manner similar to the financial reporting activities companies are subjected to, to provide information by city administrations through these reports periodically to the city-dwellers, to include city-dwellers into the resolution processes. a sustainable istanbul means a place where practices listed in the framework of this approach are applied effectively. in the absence of these practices, the concept of sustainability cannot go beyond being a new urban slogan decorating the billboards. fig. 4 the image reflecting the location of varyap meridian towers in urban fabric (rmjm, 2016) references ali, mir m., armstrong, paul j. overview of sustainable design factors in high-rise buildings. in: proceedings of the ctbuh 8th world congress. 2008: 3-5. al-kodmany k. eco-towers sustainable cities in the sky. boston: wit press; 2015. arkiv. (2016). projects. i̇stanbul sapphire. retrieved 25 october 2016. available from: http://v2.arkiv. com.tr/p9568-istanbul-sapphire.html aykan s. i̇stanbul’da kentsel sürdürülebilirlik [urban sustainability in istanbul]. in: candan a.b., özbay 49 journal of sustainable architecture and civil engineering 2017/1/18 c. (eds.). yeni i̇stanbul çalışmaları. istanbul: metis yayıncılık; 2014: 110-125. candan a.b., akbulut b. bir-iki ağacın ötesinde: istanbul’a politik ekoloji çerçevesinden bakmak [beyond one-two trees: looking istanbul at the framework of political ecology]. in: candan a.b., özbay c. (eds.). yeni i̇stanbul çalışmaları. istanbul: metis yayıncılık; 2014: 140-148. firley e., gimbal j. the urban towers handbook. chichester: john wiley & sons; 2011. fridah m. (2002). sampling in research. retrieved december 22, 2016, available from https://journals.uonbi.ac.ke/fridah_mugo/publications/sampling-research ghertner d.a. rule by aesthetics: world-class city making in delhi. new york:wiley-blackwell; 2011. hamzah t.r., yeang k. bioclimatic skyscrapers. london: elipsis; 1994. laclau e. ideology and post-marxism. journal of political ideologies, 2006; 2(11):103-114. https:// doi.org/10.1080/13569310600687882 rmjm. (2016). rmjm’ website. varyap meridian. retrieved 27 october 2016. available from: http:// www.rmjm.com/portfolio/atasehir-turkey/ sev a. sürdürülebilir mimarlık [sustainable architecture]. istanbul: yem yayınevi; 2009. yeang k. the green skyscraper: the basis for designing sustainable intensive building. munich: prestel; 2000. yem. (2016). yem’ website. metrocity. retrieved 27 october 2016. available from: http://www. yapi.com.tr/haberler/metrocitykonut-vealisverismerkezi_61103.html tuba sari research assistant, architect istanbul technical university, faculty of architecture, department of architecture main research area architecture and design, high-rise housing development address istanbul technical university the faculty of architecture taşkışla campus 34437, beyoğlu, istanbul, turkey tel.+905375944829 email: tugsar@gmail.com about the author 5 journal of sustainable architecture and civil engineering 2017/1/18 *corresponding author: indre.grazuleviciute@ktu.lt management of cultural heritage areas in rural-urban interface zones in lithuania: the elaboration of provisions of the national landscape management plan received 2016/11/10 accepted after revision 2016/12/20 journal of sustainable architecture and civil engineering vol. 1 / no. 18 / 2017 pp. 5-18 doi 10.5755/j01.sace.18.1.16753 © kaunas university of technology management of cultural heritage areas in ruralurban interface zones in lithuania: the elaboration of provisions of the national landscape management plan jsace 1/18 http://dx.doi.org/10.5755/j01.sace.18.1.16753 indrė gražulevičiūtė-vileniškė*, erika zaleskienė kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism, studentu st. 48, lt-51367 kaunas, lithuania the management of rural-urban interface areas must take into account their local peculiarities including heritage features and, vice versa, the management of cultural heritage in the rurban zones should consider the unusual dynamic and heterogeneous character of these areas. the document under analysis in this research the national landscape management plan of the republic of lithuania presents the outline for heritage management in the landscape context, although contains no particular guidelines for rurban landscapes. consequently, the aim of this research was elaborating the provisions of the national landscape management plan regarding the management of heritage areas in the active rurban zones surrounding the largest cities of the country. the article includes the discussion of the rurban problematics in lithuanian landscape planning and the analysis of the heritage questions (landscape approach, distribution, and typology) in the national landscape management plan. the research result is the provisions for management of cultural heritage in the rurban zones based on the national landscape management plan. they include the general management provisions, the protection regimes and preservation means, possible uses and protection zones, the aesthetic goals, the image and identity of rurban zones in the context of heritage management, and the need and intensity of innovations in the context of heritage management provisions as peculiar to rurban areas. keywords: rural-urban interface, rurban areas, immovable cultural heritage, heritage area, cultural landscape, heritage management, lithuania. introduction the article deals with the management of immovable cultural heritage in the rural-urban interface (further referred to as rurban with reference to a. buciega et al. (2009) and others) areas (where the characteristics of rural and urban landscapes have become blurred (ogdul, 2010; soini et al., 2012)) surrounding the largest lithuanian cities. the earlier research has demonstrated the theoretical possibility to operate in the framework of existing territorial planning system including the planning levels and the document types for the successful management of rurban areas in lithuania (zaleskiene et al., 2015). it was also ascertained that the development and management of rurban areas should address their local peculiarities (zaleskiene and grazuleviciute-vileniske, 2013) and it is possible to presume that the management of immovable cultural heritage and journal of sustainable architecture and civil engineering 2017/1/18 6 rurban and heritage problematics in the context of national landscape management plan valuable cultural landscapes in the zones of influence of urbanization should take into consideration the characteristics of the rurban areas as well. the particular object of this research is the recently adopted territorial planning document of the national level the national landscape management plan of the republic of lithuania (nacionalinio..., 2015). the solutions of this document cover the entire territory of the country (except the territorial waters in the baltic sea). the document aims at the awareness of the values and diversity and the sustainable development of the landscape of the country as a whole. the aims of document include the identifying the actions for preservation, restoration or development of traditional landscape, the development of landscape quality standards, the implementation of international and national legal documents, and the integration of the landscape management goals and means into other planning documents of different levels. these multiple are undoubtedly relevant to the development of the rurban areas of the country and to the more particular subject of this research the management of immovable cultural heritage in the active rurban zones. the authors of the national landscape management plan declare in its explanatory text that due to document’s scale and scope it does not offer the specific recommendations for the rural-urban interface areas. however, the 9th section of the text with the corresponding graphic solutions concerning the preservation of cultural identity of the country’s landscape together with the rest of the document and the previous knowledge of the rurban problematics allow implementing the aim of this research. the aim of the research is further elaborating and detailing the provisions of the national landscape management plan regarding the management of heritage areas in the rurban zones. the methods of the research include: _ the analysis of literature including the previous knowledge of the rurban problematics, especially in the context of heritage preservation and sustainable landscape development (antrop and eetvelde, 2000; westphal, 2001; sullivan et al., 2004; buciega et al., 2009; gallent and andersson, 2009; overbeek, 2009; ogdul, 2010; bardauskienė and pakalnis, 2012; soini et al., 2012; ramanauskas and dringelis, 2013; zaleskiene and grazuleviciute-vileniske, 2013, 2014; tu et al., 2016 and many others); _ the analysis of territorial planning documents mainly focusing on the drawings and the text of the national landscape management plan; _ the synthesis of the previous research experience and the obtained data and the formulation of the proposals for the management of heritage areas in the rurban zones. rurban problematics in lithuanian landscape planning the authors of the national landscape management plan use the concept “problem areas” in the context of development of the natural framework and the ecological balance. they define the problem areas as the concept and the tool used in the contemporary territorial planning. they see the problem areas as the integrated multidimensional whole of the problem territories including (nacionalinio..., 2015): _ the damaged, degraded territories; _ the territories undergoing the sharp conflicts between the use and preservation; _ the sensitive areas from the geo-ecological point of view, which require the stronger preservation regulations; _ the areas with inadequate or conflicting legal statuses; _ the territories characteristic for their competing or conflicting functions; _ the territories characteristic for poor land use indicators. 7 journal of sustainable architecture and civil engineering 2017/1/18 this definition of the problem areas presented by the planners closely corresponds with the characterization of the rurban zones (zaleskiene and grazuleviciute-vileniske, 2013). we see them as remnant, transient, contested, complex, and interdependent with the central city. thus it can be concluded that the rurban zones, especially the active ones surrounding the largest cities of the country, can be referred to as the problem areas not only form the natural framework or ecological, but also from the functional, legal, aesthetic, heritage preservation etc. points of view. the authors of another interesting document related with the rurban landscape problematics the concept of the special landscape management plan of klaipeda district municipality (klaipėdos…, 2013) provide the detailed overview of the landscape development and heritage protection problems at the level of this district municipality. this overview can be extended and applied to the zones of influence of other large lithuanian cities as well. they note that the problematic situations concerning the development and management of landscape of the municipality reflect the non-sustainable development of landscape including the conflict situations in the development of natural and culturized (anthropogeneous, anthropogenized) landscape and the conflict situations involving land use, land management and territorial planning. the obvious problems in the rurban areas are related with the conflicting overlapping regulations of different planning documents, the conflicts between the ecological function of the natural framework and the intensive urban, agricultural and other developments. the dispersed chaotic urbanization of the countryside and non-harmonious contrasting architecture, the visual disturbance from the emerging engineering infrastructure, such as wind farms (abromas et al., 2015) and advertisement development are characteristic problem issues as well. however, they are complemented with the issues of abandonment, decline and renaturalization including the decline of cultural heritage objects and areas especially in the natural areas significant from the ecological point of view, abandonment and re-growth of the agricultural areas, decline of the agricultural complexes and other structures of the soviet era (klaipėdos…, 2013). consequently, according to the authors of the document, the aesthetic problems in the rurban zones rise not only due to the intensive development, but also due to the abandonment, the decline of heritage and the spontaneous renaturalization. another issue, evident in the solutions of the national landscape management plan, especially in its 7th section concerning the protection of visual aesthetic potential of landscape and in the 3rd drawing, where the graphical solutions for the visual aesthetics potential of the country are presented, is the expressiveness and representative potential of landscapes extending in the active rural-urban interface zones. the authors of the document here identify 27 areas and sites of exceptionally protected visual aesthetic potential of the country and the proposed seaside visual protection zone. this zone and three of the areas and sites of exceptionally protected visual aesthetic potential partially overlap with the zones of influence of vilnius, kaunas, and klaipeda. moreover, the combinations of landscape aesthetic potential indicators demonstrate the diverse and expressive character of the zones of influence of the largest cities of the country. this situation raises not only the questions of landscape accessibility, representation, but shows the need of the increased attention towards the landscape quality and preservation in the rurban zones as well. heritage question in national landscape management plan the 9th section of the explanatory text of the national landscape management plan “preservation of landscape’s cultural identity” and the 4th drawing entitled “territorial priorities of cultural heritage preservation” deal with the issues the most relevant to this research and must be more closely analyzed. the landscape aspect or territorial aspect in heritage preservation employed by the authors of the document is important in the context of heritage management in the rurban zones as well as it helps at least partially preserving the fragments of authentic rural environment under the urban pressures. the text and the 4th drawing identify not only the separate landmarks or objects, such journal of sustainable architecture and civil engineering 2017/1/18 8 as objects of architectural, memorial heritage etc., but the areas, the zones of areas, the accumulations of areas, the framework of cultural heritage (fig. 1). the findings of the document under analysis regarding the distribution of immovable cultural heritage and valuable cultural landscapes in the territory of the country prove the importance of rural-urban interface landscapes, especially those surrounding the largest lithuanian cities, from the heritage preservation and presentation points of view. the explanatory text of the document states that the largest accumulations of cultural heritage (15–24 units per 25 km2 and 25–68 units per 25 km2) extend in the surroundings of the largest lithuanian cities. the distinguished areas of cultural heritage of national significance extend in the zones of influence of the largest cities of the country as well. the document identifies the zone of accumulation of cultural heritage areas of vilnius region, the zone of accumulations of cultural heritage areas of kaunas region and panemune, and the zone of accumulations of cultural heritage areas of klaipeda region and western samogitia. according to the authors of the document, these areas of national significance encompass the most significant objects in the country’s historical cultural framework dating from the second millennium b.c. to the middle of the 20th century. the text explains that “these are the areas of cultural and natural landscape in which all the types of historical urban and rural landscape characteristic to the country can be traced mounds and historic settlements (the relicts of landscape that was predominant until valakai land reform), manor residencies (the relicts of landscape developed after valakai land reform), historic urban settlements and their parts, ethnographic villages” (nacionalinio..., 2015), thus underlining the representative aspect of the distinguished areas. the typology of the heritage areas developed in the national landscape management plan distinguishes five types of areas: _ the areas where the archeological heritage is predominant (areas with heritage objects, such as the remains of prehistoric settlements, burial sites, defensive structures etc. common near the water bodies, in the lake shores and river valleys and the seaside zone); fig. 1 the zones of influence of klaipeda, kaunas, and vilnius as the accumulations and representatives of country’s heritage and landscape in the 4th drawing of the national landscape management plan of the republic of lithuania (nacionalinio..., 2015) 9 journal of sustainable architecture and civil engineering 2017/1/18 _ the areas where the architectural heritage (buildings and complexes of buildings) of different types and historic periods is predominant; _ the areas where the urban (historic towns and their parts) and ethnocultural heritage (ethnographic villages) is predominant; _ the areas where the heritage of manor residencies is predominant (mainly in the central and eastern parts of the country); _ the areas of memorial heritage (graveyards, burial sites etc.). the typology of ethnographic villages distinguished as a separate group of heritage areas in the 9th section of the document under analysis needs to be clarified in detail as it is very important for the identity of the rurban areas. according to j. bucas (2005), the heritage of ethnographic villages can be subdivided into: the ethnographic valakiniai villages (as the units of land use and land management developed after valakai land reform); ethnographic settlements of valakiniai villages; ethnographic vienkieminiai villages (as the units of land use and land management mainly developed after the land reform of the inter-war period); ethnographic homesteads of vienkieminiai villages (as the units of land use and land management); ethnographic farmsteads; individual valuable buildings of homesteads of valakiniai and vienkieminiai villages. the presented typologies help expanding and detailing the dimension “remnant” of rurban areas identified in the previous research (zaleskiene and grazuleviciute-vileniske, 2013) and denote the existence and importance of cultural heritage and cultural landscape in rurban areas and rurban research. this typology, when applied to the rurban areas in lithuania, can be integrated with the typology of the relicts of historic rural landscape types developed by j. bucas (2001) for the more sustainable heritage management and preservation in the rurban zones. elaboration of the provisions of the national landscape management plan regarding management of cultural heritage in the rurban zones the mutual influence of rurban areas and cultural heritage as it is clearly seen in this overview, the concepts of the problem area, the rurban area and the area with heritage features or heritage area are closely interlinked. the rurban problematics (the characteristics of rurban landscapes) affect the heritage management and of course the heritage objects and areas themselves in the zone of influence of the city both manifesting as the conflicting uses, the pressure for development, the limited possibilities to maintain the authentic function and environment, the contrasting aesthetics and the decline and abandonment. for example, the treatment of the sensitive archeological heritage in the potentially transient, complex, contested, interdependent rurban landscape raises additional issues and the sustainable development of such landscape in accordance with the traditional principles of spatial arrangement, as mentioned in the document, might be compromised or influenced by those features. thus, the heritage management should incorporate the rurban issues (fig. 2). provisions of management of heritage areas in the context of rurban problematics the explanatory text of the document distinguishes the priority management aims, the trends of management and the complex preservation means, which should be applied for the heritage areas of national significance. it is possible to see that the identified aims, trends and means tend to be more conservative and more directed towards preservation and maintenance and not towards renovation, interpretation or innovations due to the high importance of these areas. for example, the management aims for the heritage areas of the national significance are the following: the preservation of the authenticity of valuable properties and the surrounding landscape; the maintenance of the harmony of historical and cultural landscape, its’ plan and spatial structure; the revealing and highlighting of values of associative landscape elements (nacionalinio..., 2015). the last goal of revealing and highlighting values might involve some interpretation and innovation journal of sustainable architecture and civil engineering 2017/1/18 10 as a means; however, the conservative goals of preservation and maintenance can conflict with the dynamism of the rurban sphere and may require the amendments. moreover, all the three heritage areas of national significance are closely linked with the rurban problematics, as it was mentioned before that all of them encompass the largest cities of the country. however, the management goals as well as trends discussed below in principle do not reflect the issues of urban pressure and the rural-urban interactions. fig. 2 the possible influences of the features of the rurban zones on the provisions for management of heritage areas from the national landscape management plan the characteristics of the rurban landscapes can influence the aesthetic expression of the rurban areas, the heritage management approaches and are mutually interdependent with the cultural heritage existing the rurban zones; meanwhile the heritage management provisions in the rurban areas can affect both the heritage objects and sites themselves and the image of the rurban landscapes; the relicts of historic rural landscapes of different types in the rurban zones are very important as they both determine the character and identity of rurban areas and influence heritage classification in the rurban zones. the distinguished trends of management of the territories of valuable cultural properties include conservation, restoration, adaptation to historical or close to historical functions, and the adaptation to the needs of tourism and recreation (nacionalinio..., 2015). all these trends are common in heritage preservation practice and can be applied in the rurban context as well. the adaptations to the needs of tourism and recreation are of considerable importance in the rurban space, bearing in mind the increased flows of visitors and recreational loads due to the presence of urban center. the adaptation to historical or close to historical functions might undergo some amendments as the urban influence often induces radical changes of functions in the heritage objects of rural origin. the authors of the document recommend the maintenance of the valuable links between the natural areas and the existing built structures, and the preservation of the characteristic features of natural-cultural landscape complex and the historical elements of the structure of the territory, when dealing with the territories included into the register of cultural properties (nacionalinio..., 2015). this of course is of increasing importance under the urban pressure; however, the coordination of the integration of the new rurban developments with the existing valuable landscapes and developing the specific rurban identity become a challenge directly linked with the landscape aspect of heritage preservation as well. the authors of the document note that in some territories in the heritage areas of national significance the concentration of heritage properties is very high reaching from 25 to 68 objects per 25 km2. they also underline the tradition of heritage preservation in these territories, as some of the heritage objects are under the state protection for more 11 journal of sustainable architecture and civil engineering 2017/1/18 than fifty years (nacionalinio..., 2015). the relatively long lasting tradition of heritage preservation mentioned in the document should be complemented with the new knowledge, experience, new issues of heritage management under pressures of urbanization, under the increasing anthropogenization, rapid landscape changes and conflicting interests. in order to preserve the most valuable structural elements of the country’s historical cultural framework and to implement the priority aims of cultural heritage preservation, the text of the document provides the complex preservation means from the landscape point of view for the heritage areas of national and regional significance. they include: constant monitoring of changes of cultural landscape and heritage; providing the status of the property protected by the state or municipality for the valuable cultural properties existing in these territories; providing the adequate support from the state for the management of valuable cultural properties existing in these territories; the inventory and the adjustment of inventories of valuable cultural properties existing in these territories; more comprehensive and complex planning of heritage preservation including the preparation of the special plans for cultural heritage sites and their protection zones, grouping and integrating into the territorial units the adjacent heritage objects with similar landscape features; applying intensively the principles of territorial protection of cultural heritage by creating different kinds of protected areas; considering the possibilities to create the additional protection zones for valuable cultural heritage properties (nacionalinio..., 2015). the importance of the distinguished means from the rurban landscape point of view can be confirmed as well. for example, the constant heritage and landscape changes monitoring and inventory, ranging from the information regarding land use and land cover changes (alphan and guvensoy, 2016; alphan and derse, 2013; ramachandra et al., 2013) to the recording on site of specific heritage objects, in the context of rapid changes of the rurban spaces is increasingly important. providing the legal status is the priority in the rurban territories vulnerable to change. the emphasis on the territorial protection and protection zones helps coping with the urban pressures and other difficulties in protecting the cultural and natural resources at the rural-urban interface (westphal, 2001). however, this deepens the conflicts of interests between preservation and development as well and should be wisely managed, otherwise excess protection zones can be frequently violated, sometimes can hinder useful development or cause the territorial urban expansion, so-called sprawl. moreover, the same principle of the increasing territorial protection of cultural landscape is not reflected in the 1st drawing of the document, where the perspective recommended protected areas and recreational parks are identified, as none of these new proposed protected areas are situated in the rurban areas. provisions of management of heritage areas are summarized in the table at the end of the explanatory text of the national landscape management plan. we present the modification of the table and its adaptation to the heritage preservation in the rurban context (table 1). here we identify the areas of historic towns and their parts in rurban zones, the areas of ethnographic villages in rurban zones, the areas of manor residencies in rurban zones, the areas of architectural heritage in rurban zones, the areas of archeological heritage in rurban zones, and the areas of memorial heritage in rurban zones. they are listed in the table according to the importance in shaping the identity of the rurban areas. the most relevant types of the relicts of historic rural landscapes are linked with these categories as well. the provisions of management of heritage areas from the national landscape management plan including management, protection regimes and means, uses, and protection zones are modified bearing in mind the rurban context. the aesthetic categories or the categories of the image of the rurban areas are linked with the types of cultural heritage areas as well (fig. 3). protection regimes and preservation means identified in the table can be defined as follows: conservation – elimination of the influence of the factors detrimental to the valuable properties of heritage object and consolidation of the authenticity features of the object by research based heritage preservation, construction, and land management works (lietuvos…, journal of sustainable architecture and civil engineering 2017/1/18 12 2005); restoration – conservation of all the extant authentic parts or elements of the heritage object, re-creation of the lost parts or elements, preservation, revealing, and highlighting heritage features by research based heritage preservation, construction, and land management works (lietuvos…, 2005); renovation – improvement of the physical condition of existing objects (heritage…, 2011) preserving the extant valuable authentic parts or elements of the heritage object, re-creating or replacing the lost parts or elements; interpretation – diverse ways of presenting the cultural significance of a heritage object (heritage…, 2011), innovations – new ideas and technologies applied for modifying the historic structure in order to highlight its cultural significance and extend its useful life (heritage…, 2011). fig. 3 the descriptions of the aesthetic perceptual categories under sustainable landscape development distinguished by w. nohl (2001) and their possible application to the different types of heritage areas existing in the rurban zones aesthetic goals, image and identity of rurban zones in the context of heritage management the distance from the urban areas and the degree of urbanization influence the attributes of natural and rural as well as recreational (liu et al., 2016) areas. the question can be posed what kind of identity the territories rich with heritage surrounding the large cities of the country will have, where the processes of rural-urban interface take place. however, the national landscape management plan does not envision any clear image or identity for these areas. the 2nd drawing of the document, where the landscape management regulation strategy and trends are presented, distinguishes only two types of regulations for the present and perspective urbanized areas: the intensive urbanization regulations and the extensive urbanization regulations. it is easy to see that these broad categories can encompass a very vast array of landscape images and identities from sustainable cultural landscapes to degraded or monotonous unsustainable territories. in the previous research (zaleskiene and gražuleviciute-vileniske, 2013) we 13 journal of sustainable architecture and civil engineering 2017/1/18 table 1 provisions for management of heritage areas in the rurban zones adapted from the national landscape management plan (nacionalinio..., 2015) types of cultural heritage areas as distinguished in the national landscape management plan in the rurban context the most relevant types of the relicts of historic rural landscape provisions for management of heritage areas in the rurban zones management provisions protection regime and preservation means use protection zones 1. areas of historic towns and their parts in rurban zones highlighting valuable features of landscape in the rurban environment; sustainable development of rurban landscape; identity development of rurban areas respecting the traditional formation of spaces conservation; restoration; renovation; interpretation; innovations residential use; uses for recreation and tourism; commercial use; public and general use; improvement of observation possibilities of silhouettes and panoramas; revealing and highlighting visual links; protection from aggressive urbanization 2. areas of ethnographic villages in rurban zones valakinis vienkieminis highlighting of the features of historic landscape in the rurban environment; protection and development of the local identity; development of links between traditional, new architecture, and nature conservation; restoration; renovation; interpretation; innovations authentic and similar to authentic use; agricultural use; residential use; uses for recreation, cultural tourism preservation and maintenance of agricultural environment; protection form aggressive urbanization 3. areas of manor residencies in rurban zones valakinis preservation and re-use of manor heritage and preservation of relicts of historic rural landscape in rurban environment; identity development of rurban areas conservation; restoration; renovation; innovations uses for recreation, tourism; public, general uses; residential, commercial, agricultural uses maintenance of immediate surrounding environment; preservation of the relicts of agricultural environment; maintaining possibilities to observe silhouettes and perspectives 4. areas of architectural heritage in rurban zones valakinis vienkieminis preservation and highlighting of values; sustainable development of rurban landscape; identity development of rurban areas respecting the traditional formation of spaces conservation; restoration; renovation; interpretation; innovations public use; residential use; uses for recreation and tourism highlighting valuable heritage objects; maintaining their immediate environment 5. areas of archeological heritage in rurban zones ikivalakinis highlighting and presenting the archeological heritage conservation; interpretation; innovations recreational use; general use bearing in mind more intensive visitor flows; formation of open spaces for observation; protection from immediate aggressive urbanization 6. areas of memorial heritage in rurban zones protection of memorial heritage with its surroundings significant for its value and presentation conservation; interpretation; innovations authentic use; use for tourism formation of open spaces for observation; protection from immediate aggressive urbanization journal of sustainable architecture and civil engineering 2017/1/18 14 had employed the four aesthetic perceptual categories under the sustainable landscape conditions “the beautiful”, “the new sublime”, “the interesting”, and “the plain” originally formulated by w. nohl (2001) (for the details see the fig. 3). they can function as the possible guidelines in the development of the image of the rurban areas of the country, reflecting relationship between the aesthetics and functionality of landscape (gallent and andersson, 2009). the question of the heritage objects and valuable cultural landscape existing in the rurban zones was partially addressed there as well: the most suitable trends for the specific type of rurban area were identified bearing in mind among other factors the presence and typology of the relics of historic rural landscapes characteristic in lithuania. in this research we further elaborate the links between the possible image and aesthetics of the rurban area and the typology of cultural heritage existing in it. for example, the concepts “the beautiful” and “the interesting” are identified as the most suitable concepts for heritage preservation in the rurban areas for all six types of cultural heritage areas distinguished in the national landscape management plan (fig. 3). however, the category “the (new) sublime” can be applied to the areas of archeological and memorial heritage, where the radical innovations or even any kind of disturbances are not allowed and the formation of open spaces surrounding the valuable properties are necessary in order to protect them from the immediate and sometimes aggressive urbanization. the category “the plain” denoting the sustainable agricultural use of various kinds can be suitable for the areas of ethnographic villages or sometimes even to the areas of manor residencies, where the character of the rural landscape must be maintained under the urban pressures. as the urban areas most often expand by converting farmland into residential sites (sullivan et al. 2004) and increasingly rural areas find themselves in an ambivalent urban context (overbeek, 2009); thus the land management tools must be applied to protect agricultural environment (westphal, 2001). the identity of the rurban areas cannot be seen in isolation. the high heritage values and distinguished landscape aesthetics outlined in the document under analysis in the zones of influence of vilnius, kaunas, and klaipeda dictate the need to incorporate the image of the rurban areas into the development of the image of the central city as well as of the country. the fig. 4 demonstrates how the image of the central city could incorporate or be shaped by not only the urban heritage mainly located the central part, but also by the rural heritage and landscapes extending at the urfig. 4 the identity of the city should be constructed integrating both the urban dimension and the features of the surrounding landscape. the scheme shows the identity of the central city driven by the culture and nature; by the urban heritage and the rural heritage encompassed by the city, by the green areas in the inner urban fabric and the nature at the urban fringe, by the urbanity and the agricultural, rural activities structured by the city ban fringe as well as the natural elements and landscapes. the need and intensity of innovations in the context of heritage management provisions as peculiar to rurban areas as it was mentioned above, the document underlines the landscape approach, the territorial approach to heritage management. it is easy to see that larger territorial units extending in the zones of 15 journal of sustainable architecture and civil engineering 2017/1/18 influences of the cities would be inevitably affected by the urban pressures and forced or must inevitably accommodate some changes or innovations occurring due to the intensification of anthropogenic activities. in the context of heritage preservation in such dynamic territories as the rurban ones, one of the most important factors is to determine the possible character and degree of changes. the main idea here is that the allowed and even welcomed changes are the sustainable innovations that do not diminish the heritage values, even create new values, and help developing specific rurban identity. the fig. 5 demonstrates the factors, which influence the degree of innovations in the heritage areas in the rurban zones. as it can be seen below, these factors are linked with the value of the heritage object itself, the type and corresponding vulnerability of the heritage area, with the aspects of typology of cultural landscape, and with the intensity of urban influence as well as such issues as general landscape sensitivity and the identified aesthetic class. the figure shows four aesthetic classes (vi is the highest denoting the most aesthetically pleasing and valuable landscapes). the issues of landscape sensitivity and aesthetic classes of rurban areas are elaborated in detail the earlier research (zaleskiene and grazuleviciute-vileniske, 2014). bearing in mind the importance of innovations in heritage management in the rurban context, the four degrees of innovations (more meaning the visible interventions in heritage objects and areas, not the innovations in heritage preservation field or techniques) were distinguished. the definition of each degree are presented below: i very intensive (changes of function, layout, volume, use of contemporary contrasting materials) innovations. the conditions for these radical interventions may be: the i, ii aesthetic classes, low sensitivity of landscape, high degree of urbanization, kolukinis type of relicts of historic rural landscape, architectural heritage area, comparatively low heritage value, and regional, local heritage significance. ii intensive (changes of function, layout, slight changes of volume, use of contemporary materifig. 5 factors determining the degree of innovations in heritage management in the rurban zones journal of sustainable architecture and civil engineering 2017/1/18 16 als). the conditions for this type of interventions may be: i, ii aesthetic classes, medium and low sensitivity of landscape, high and medium degree of urbanization, vienkieminis and kolukinis types of relicts of historic rural landscape, urban or architectural heritage area, comparatively low or medium heritage value, regional or local heritage significance. iii medium (close to authentic or authentic function, slight changes of layout and volume, use of authentic and contemporary materials). the conditions for this type of interventions may be: ii, iii aesthetic classes, medium and high sensitivity of landscape, medium to low degree of urbanization, ikivalakinis, valakinis, vienkieminis types of relicts of historic rural landscape, manor residencies or urban heritage area, medium heritage value, national or regional heritage significance. iv low (close to authentic or authentic function, slight changes of layout, use of authentic or close to authentic materials). the conditions for this type of interventions may be: iii, iv aesthetic classes, high sensitivity of landscape, low degree of urbanization, ikivalakinis, valakinis, vienkieminis types of relicts of historic rural landscape, archeological or memorial heritage area, high heritage value, national heritage significance. 1 the problems of heritage preservation in rurban areas should be dealt within the wider context of urban and landscape development as the rurban problematics both affects the heritage under consideration and its preservation aims, trends, and means. 2 rurban areas surrounding the largest lithuanian cities reflect the general problematics characteristic to the rural-urban interface zones. however, their potential related with rich cultural and natural landscape and high concentration of diverse immovable cultural heritage reflected in the national landscape management plan and other documents as well as the representation possibilities deserve the specific attention from cultural heritage preservation point of view. 3 the provisions of the national landscape management plan can be used as a valuable resource for developing the strategies for management of immovable cultural heritage in the rurban context. the priority heritage management aims, the trends of management and the complex preservation means in the landscape context identified in the document can be adapted to the rurban areas with heritage features. however, the characteristics of the rurban space, such as transient, contested, complex, and interdependent with the central city and the resulting pressure for changes and the need of innovations must be taken into account. 4 the proposals for heritage management in the rurban zones elaborated using the solu-tions of the national landscape management plan include: _ the discussion and modifications of the typology of and management provisions for the heritage areas; _ the proposals for determining the intensity of innovations; _ the links between the typology of heritage areas, the management provisions, and the desirable aesthetics and the image of the rurban area. they can be applied developing the strategies for heritage management in the rurban context. conclusions abromas j., kamičaitytė-virbašienė j., ziemeļniece a. visual impact assessment of wind turbines and their farms on landscape of kretinga region (lithuania) and grobina townscape (latvia). journal of environmental engineering and 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rural-urban interface zones. acta biologica universitatis daugavpiliensis, 2013; 13: 15-30. indrė gražulevičiūtė-vileniškė assoc. prof. kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research areas preservation and management of built heritage, application of principles of sustainability to architecture and landscape, rural-urban interface, rurban landscapes address studentu street 48, kaunas, lithuania, lt-51367 e-mail: indre.grazuleviciute@ktu.lt about the authors erika zaleskienė phd student kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research area formation of green areas, rural-urban interface, rurban landscapes, landscape aesthetics address studentu street 48, kaunas, lithuania, lt-51367 e-mail: erika.zaleskiene@ktu.lt 71 journal of sustainable architecture and civil engineering 2019/2/25 *corresponding author: aniebietabasi.ackley@vuw.ac.nz exploring post occupancy evaluation as a sustainable tool for assessing building performance in developing countries received 2018/07/30 accepted after revision 2019/01/14 journal of sustainable architecture and civil engineering vol. 2 / no. 25 / 2019 pp. 71-84 doi 10.5755/j01.sace.25.2.21176 exploring post occupancy evaluation as a sustainable tool for assessing building performance in developing countries jsace 2/25 http://dx.doi.org/10.5755/j01.sace.25.2.21176 edidiong ukpong department of architecture, university of nigeria, nsukka, nigeria aniebietabasi ackley* school of architecture, victoria university of wellington, new zealand in recent years, the concept of using post occupancy evaluation (poe) for building performance assessment has attracted much attention globally because of its benefits in enhancing future design decisions. however, developing countries give little or no concern to the practice of improving design outcomes using poes. in nigeria, buildings are rarely evaluated once they are handed over to the clients. this study explored the use of poe as a sustainable tool to assess building performance in developing countries with nigeria as a case study. the method of data collection was firstly through a systematic literature review where existing and current conceptual body of knowledge in peer-reviewed journals, electronic databases (science direct and google scholar), conference proceedings, and published articles were appraised; with a specific focus on key issues of poe, such as: its definition, evolution, phases, levels, dimensions, benefits and application as a sustainable tool for building performance. the findings from the literature informed the use of interviews to gather the perception of building professionals on the use of poe for building performance assessment. a total of 117 building professionals including architects, engineers, planners and surveyors were interviewed. the data analysis involved descriptive and inferential statistics (frequency count and simple percentages). the study findings revealed that building occupants are a valuable source of information on building performance and that poe methods should be simple and building typology specific. the interviewees suggested that poes could provide useful benchmarking data to establish best practices for delivering sustainable building developments in nigeria. it is expected that the findings of this study will encourage policy makers to consider regulations that will enhance the use of poes for building performance analyses to feed forward the positive and negative lessons learned to improve the design of current and future building developments in developing countries. keywords: assessment, developing countries, performance of building, post occupancy evaluation (poe), sustainability. journal of sustainable architecture and civil engineering 2019/2/25 72 building users desire buildings to support their yearnings and meet their expectations in accessibility, productivity, health, comfort and satisfaction (akpan-idiok and ackley, 2017; ackley et al., 2018). this is crucial since people spend up to 90% of their time inside buildings where they work, study or live in (ferreira and cardoso, 2014; nathanson as cited in el-sharkawy, 2014; ackley et al., 2017). the idea of sustainability, green buildings, and energy efficiency has made the construction industry and owners to be concerned about how their buildings perform. building performance can be defined as the degree to which a building can meet any or all these expectations. several tools and theories have been developed to appraise a building from environmental compliance to energy performance. post occupancy evaluation (poe) is one of the existing tool (aliyu et al., 2016; sanni-anibire and hassanain, 2016). poe is the process of evaluating the building in a systematic and rigorous way after it has been occupied. in nigeria, buildings are rarely evaluated once they are handed over to the clients. this lack of appraisal brings about repetition of design mistakes and even when some reassessments are done; it is usually done in a non-systematic manner. the absence of regularized feedback from performance to planning and construction phases becomes ever more relevant under the current conditions which include (meir, 2008 as cited in meir et al., 2009): (1) continuous rise in the consumption of energy, both per capita and in absolute terms; (2) the realization that fossil fuels are being depleted and that their use has adverse environmental, health, social, political and security implications; and (3) people spending 80–90 per cent of their lives in buildings, which means that the indoor conditions should have positive imprint on well-being, health and productivity (el asmar et al., 2014; jurado et al., 2014; marchetti et al., 2015; radwan, 2014; rovelli et al., 2014; thornes et al., 2016; tofful and perrino, 2015). poe offers a sustainable building performance tool to create a balance for the increasingly stringent environmental constraints and occupant comfort and satisfaction in buildings. greater attention has been given to poe studies but majorly in america, europe and asia (leaman et al., 2016; mallory-hill et al., 2012; morrison, 2008; preiser and nasar, 2008; tookaloo and smith, 2015). however, less attention is given to poe in nigeria and the few poes carried out are focused on subjective assessment of buildings (adedayo and zubairu, 2013; ibem et al., 2015; ilesanmi, 2010; lawrence, 2012; nwankwo et al., 2014). this paper focuses on exploring poe as a sustainable tool for building performance in nigeria, aimed at improving the knowledge of poe in developing countries. building performance and its evaluation (using poe) have received increased attention in recent years, particularly with respect to residential and commercial buildings (brown, 2009; huat and bin akasah, 2011; olubunmi, 2013; tanyer and pembegül, 2010). however, in developing countries; little concern is shown in the practice of building performance evaluation (agyekum et al., 2016; olatunji, 2013). leaman (2004) as cited in olatunji (2013) stated that building performance is yet to be taken as an area of legitimate interest in the academics, thereby calling for further studies to elucidate poe as a sustainable tool in that direction. nigeria is yet to be in the fore front of bringing the knowledge and practice of poe as a sustainable tool to bear (jiboye, 2012). this study explores the benefits of poe as a sustainable tool for building performance in developing countries with a case study of nigeria. introduction literature review and theoretical framework building performance building performance is the behaviour of a product in use in bs5240. it denotes the physical performance characteristics of a building as a whole and/or its parts (clift, 1995 as cited in jiun, 2005). it is the capacity of a building to meet its expectation and desired intention. building occupants’ interactions with the physical, business and work environments of a building defines the performance of the building. this performance approach involves the definition of user requirements and performance criteria to be used in a systematic appraisal for predicted or actual 73 journal of sustainable architecture and civil engineering 2019/2/25 performance throughout the entire building life cycle (gajendran, 1998 as cited in jiun, 2005). there are specialised tools that can be used in measuring building performance and they include; post occupancy evaluation, building in use, concept of total building performance and building diagnostics, building quality assessments, orbit and breeam (jiun, 2005), elsaay and othman (2013) included building quality assessment (bqa) and serviceability tools and methods (stm). post occupancy evaluation (poe) and its evolution poe is an examination of the effectiveness of occupied built environments for human users that focuses on the assessment of occupant satisfaction and functionality of a space; where effectiveness corresponds to the achievement of personal and organizational goals by the enhancement of physical and organizational factors (turpin-brooks and viccars 2006; zimmerman and martin, 2001). “poe is the measurement of building performance throughout the life cycle of a building from initial concept through occupancy such that the information gathered is used to improve future building designs” (vischer 2001; zimmerman and martin, 2001) the roots of poe are based in academia in the mid-1960s; however poe is based on a much older idea known as the ‘performance concept’ of building, which dates back to the code of hammurabi (1800 bc)(mallory-hill et al., 2012). interesting account of the evolution of poe are recorded in cooper (2001) and preiser and nasar (2008) specifically in the uk. in 1960, sim van der rijn and victor hsia carried out evaluation case studies of university dormitories even though not called poes, these evaluations were among the first systematic attempts at assessing building performance from the building users’ point of view (preiser and nasar, 2008). in the 80s, lots of poe activity were carried out in the uk, canada, new zealand, australia, and the us on public works projects, government buildings, airports, etc., resulting in very sizeable and significant poe studies. and the first textbook on poe was written by preiser, rabinowitz and white in 1988 (preiser and nasar, 2008), and since then several terms have been suggested to poe by academics and others working in the industry such as; environmental design evaluation, building in use assessment, facility assessment and post-construction evaluation have been used to depict poe in an attempt to better reflect on its aims and objectives (council, 2002). phases of poe figure 1.0 identifies 3 phases and 9 sub phases in a poe process (council, 2002). _ the 1st phase: planning involves review for (1) reconnaissance and feasibility, (2) planning for the resources and (3) the research planning that may be needed for a particular level of poe. schedule, cost, and human resources are determined; and plans for data collection procedures, time and amounts are the parameters laid out. _ the 2nd phase: conducting starts with (4) initiating on-site data collection process (5) monitoring and management of data collection procedures, and (6) data analysis. _ the 3rd phase: applying involves (7) reporting findings, (8) recommending actions and (9) reviewing outcome. this is the most tedious part from the client’s view since actions are supposed to be taken at this stage based on the recommendations made. the feed-forward arrow into next building cycle is vital as the best application of poe is its use as a factor in pre-design phases of the building delivery cycle. poe assesses several aspects of the occupied buildings’ functional and technical performance, both chemo-physical (indoor environment quality (ieq), indoor air quality (iaq) and thermal performance, acoustic and visual quality), as well as more subjective and interactional (space use, user satisfaction, etc.). poe draws on an extensive quantitative and qualitative toolkit: measurements and monitoring, and methods such as walk-throughs, observations and user satisfaction questionnaires and semi-structured and structured interviews (meir et al., 2009). journal of sustainable architecture and civil engineering 2019/2/25 74 levels (types) and dimensions of poe most of the literature submitted to these three levels to poe and are summarised as: indicative, investigative and diagnostic poe (aliyu et al., 2016; eke et al., 2013; elsaay and othman, 2013; hadjri et al., 2009). 1. indicative poes involves quick (two or three hours to one or two days) archival, walkthrough and document evaluations involving structured interviews with key personnel, group meetings with end users as well as inspections. the aim is to highlight major strengths and weaknesses. 2. investigative poes are more in-depth analyses, utilising interviews and questionnaires, focus group reviews usually across many buildings of the same or similar type to produce more robust data. this could take a week to several months. 3. diagnostic poes are regarded as being the most sophisticated of the methodologies. this takes several months to years. they tend to have a broad system wide focus on many comparable facility types, focusing on a broad range of technological and anthropological areas of research. they produce high validity and generalizability of data collected with the potential of being transformed into guidelines for use in the public realm. generally, this includes: air-handling, heating, measuring ventilation rates, lighting levels, energy and water usage, co2 emissions, thermal, air and visual quality and acoustic performance. zimring and reizenstein in 1980 (as cited in bhawani, 2015), summarised three dimensions of poe and they include: (1) generality and specificity determines the nature of the poe data collected. for example, a study based on impact of floor-plan configurations on users is driven by generic data collection, whereas a study based on specific apartment complex for students is targeted towards specific settings. (2) breadth of focus covers the extent of review during an evaluation. the focus of review can be a single physical characteristic of a single setting versus multiple settings. it can also be evaluation of holistic systems such as the social and physical workings of a combination of settings or influence of social trends on the organizational structure that operates in those settings. (3) timing of application which suggested that while some studies can be conducted on a short-term basis to inform design and planning decisions, some may be conducted on a longer term to develop heuristics and facilitate future planning. although most poes have a primary goal, a single study may have multiple goals or multiple studies may have a common goal. fig. 1 post occupancy evaluation: evolving performance criteria (council, 2002) 75 journal of sustainable architecture and civil engineering 2019/2/25 this research focused on making a case for poe as a sustainable tool for building performance in nigeria, which gives the focus of this poe specific in terms of the first two dimensions. and for the third dimension, this study is intended to help nigeria gain from the short and long-term benefits of poe. building performance assessment using poe: the global case a study by dahlan et al. (2009) focussed on naturally ventilated student housing with ceiling fans and deducted that occupants’ perception of indoor thermal comfort was affected by outdoor conditions in agreement with previous research by de dear and brager, (2002). brown and cole (2009) examined the influence of knowledge on occupant behaviour studying green and non-green academic (departmental) buildings in a university campus. through the use of poe tools they found that sub-optimal comfort conditions were caused by (hadjri and crozier, 2009) absence of timely feedback and poor comprehension. preiser (2002) highlighted the need for continual building performance evaluation and indicated that poes are different from other evaluation methods. poes focus on technical and non-technical parameters providing a holistic performance picture; this was also posited by (hadjri and crozier, 2009). augenbroe and park (2005) reinforces the importance of measuring building performance addressing key performance aspects such as: energy, lighting, thermal comfort, maintenance and indoor air quality. fowler et al. (2005) emphasized that the lack of performance measured data hampered the adoption of sustainable design and construction. this minimizes the savings realized, as stakeholders are simply unaware of the information. turpin-brooks and viccars (2006) discussed the importance of developing robust and effective poes as part of a sustainable approach to workplaces. they stated that poes are effective in addressing client satisfaction, and user needs as part of sustainability assessments. bordass et al. (2009) affirmed turpin-brooks and viccars (2006)’s position. a study of us data on residential energy consumption, steemers and yun (2009)) found that occupant behaviour and socio-economic parameters were also important components in the equation of energy consumption and sustainability demanding poe to salvage the situation. this findings is in agreement with a study carried out by brown et al. (2010) and meir et al. (2009). another study by guerra-santin and itard, (2010) used surveys and questionnaires to discuss the influence of occupants on energy consumption. they studied a residential application in netherlands and showed that the type of heating/cooling system selected had an influence on occupant consumption behaviour. the importance of tracking, measurement and on-going building performance awareness was a finding in masoso (2010) study on waste energy consumption during non-occupied periods of six buildings. the suggested that building performance awareness is the key to reducing energy consumption in buildings and promoting sustainability. this implies that occupants could have a great impact in reducing energy consumption in buildings. poe studies have been carried out worldwide in both the private and public sector, but have rarely led to ‘lessons learned’ and design changes (ornstein and ono, 2010) and the lack of systematic poe use by professionals has led to a situation where mistakes are repeated and every building is a prototype. the impact of occupant behaviour on building energy consumption was studied by yu et al. (2011). their findings indicated occupant behaviour as the lead factor influencing building energy consumption. a study (martani et al., 2012) carried out on two non-domestic buildings on the mit campus showing operation of heating, ventilation and air conditioning systems suggested other factors other than occupancy. these factors were closely related to external temperature, however there was a significant correlation between occupancy and electricity consumption. toftum et al. (2009) studied the energy consumption in two different types of buildings in singapore one with active cooling and one with passive strategies. they found no significant energy consumption or significant comjournal of sustainable architecture and civil engineering 2019/2/25 76 plaints by those who experienced higher temperatures in the passive building, even though the differential between the two were vastly different. berker et al. (2011) carried out a study on the user evaluation of sustainable buildings looking at parameters such as indoor climate, mechanical operation, user attitudes and general satisfaction. they highlighted ultimate performance of a building is reliant on users. a study (yang and wang, 2013) similar to a study by klein et al. (2012) focused on the creation of a multi-agent intelligent control system to interact with occupants by responding to their requests and obtaining feedback based on their behaviours. post occupancy evaluation: the nigerian case given the rising cases of building collapse in nigeria and the poor maintenance of institutional buildings, it is apparent that poe is not well explored in nigeria. this assertion is supported by olatunji, (2013) who states that poe is not carried out in most institution buildings in nigeria (olatunji, 2013). this has resulted in institutional buildings being regarded as inadequate and deplorable with low occupants’ satisfaction (adamu and shakantu, 2016; aluko, 2011; ojogwu and alutu, 2009; ojo et al., 2013; ubong, 2007). government office buildings in nigeria are generally faced with premature but steady and rapid deterioration, decay and dilapidation due to lack of maintenance (olagunju et al., 2013). a poe carried out in a school building in nigeria suggested that the negative experiences expressed by the study participants point to the need for building performance evaluation (olatunji, 2013). another study observed that poe as a systematic method of collecting data on buildings in-use has not found wide usage for housing in nigeria (jiboye, 2012; nwankwo et al., 2014). olatubara and fatoye (2006) and olatubara (2008) were cited to have observed that unfortunately most state governments in nigeria provide housing estates and do not regard building evaluation of these housing estates as an area of legitimate interest (olubunmi, 2013). there is little factual evidence to ascertain the key problems and the specific factors of ‘ inadequacy ’ or ‘ non-satisfaction ’ in existing public housing estates (ilesanmi, 2010), making a call for poes. users of public buildings are generally not satisfied with the building design and design decisions taken with implications that the building has failed to meet the majority of the needs and aspirations of the user of the public buildings in the selected cities in nigeria (adedayo and ayuba, 2013). motor parks have not met the needs of their users in minna because they are inadequate and require major transformation (adedayo and zubairu, 2013). another study by adeniran and akinlabi, (2012) suggested that because of the form adopted in the architectural design of the senate building under study, satisfactory levels of indoor environmental comfort was not achieved and appeared to have been sacrificed for the high aesthetic value achieved. benefits of poe as a sustainable tool for building performance in nigeria brundtland commission (1987), defined sustainable development to be a development that “meets the needs of the present without compromising the ability of future generations to meet their own needs” (ijatuyi olufunto and olatunde, 2013). under the mounting pressure of energy shortage, one approach to minimize the contradiction of the increasing demand for comfort in buildings and the need to decrease the use of energy is to design sustainable buildings in an informed and responsive way (meir et al., 2009; zeiler and boxem, 2008; zeiler et al., 2007). as a result, integration between enduser needs and building performance is indispensable. poe makes a case in this stand and its short-term benefits include obtaining users’ feedback on problems in buildings and the identification of solutions; medium-term benefits include feed-forward of the positive and negative lessons learned into the next building cycle; long-term benefits aim at the creation of databases and the update, upgrade and generation of planning and design protocols and paradigms. exploratory research is an examination into a subject to gain further insight identifying issues that could be the focus of future research. the methodology used in this study was firstly a systematic 77 journal of sustainable architecture and civil engineering 2019/2/25 literature review which focused on appraising existing and current conceptual body of knowledge, previous published studies bringing to the fore the key issues of poeits evolution, phases, methods, levels, application as a sustainable tool for building performance and its benefits. peer-reviewed journals, electronic databases (science direct and google scholar), and conference proceedings where direct sources of the body of literature. the study reviewed and analysed literature on post occupancy evaluation (poe) and building performance bringing out germane points on poe concept. the second method used to gather data was through interviewing building professionals to gather their perception on the use of poes for building performance analyses in nigeria. interviews can be defined as a qualitative research technique which involve social interaction with participants to explore their perspectives on an idea (groat and wang, 2004). interviews help to collate the story behind a participant experiences and pursue in-depth information around a topic (mcnamara, 1999). based on the response of the respondents, interviews are completed by the interviewer. in this study, an informal conversational, semi structured face to face interview with predetermined questions were used to gather the perspective of 117 building professionals on the use of poes for building performance analyses in nigeria. the data analysis involved descriptive and inferential statistics (frequency count and simple percentages). methodology results between 16th and 31st november 2018, informal conversational, semi structured face to face interview was carried out with 117 interviewees. the interview allowed each interviewee to express their perspective about poe in nigeria. the charts and tables below present the responses collated from interviewees. as shown in table 1, many interviewees were males 61.5% (n=72), between the ages of 26 to 35 years 43.6% (n=51). majority of interviewees were architects 41.0% (n=48) and 40.2% (n=47) attained a master’s degree tertiary education level. description frequency (n=117) percentage (%) gender male 72 61.5 female 45 38.5 age 18-25 37 31.6 26-35 51 43.6 36-50 19 16.2 above 50 10 8.5 field of practice architect 48 41.0 engineer 31 26.5 planner 23 19.7 surveyor 15 12.8 qualification diploma 29 24.8 bsc 35 29.9 msc 47 40.2 phd 6 5.1 years in practice 0-1 years 7 6.0 2-5 years 14 12.0 6-10 years 30 25.6 11-20 years 56 47.9 over 20 years 10 8.5 table 1 socio-demographic data of interviewees n=117 journal of sustainable architecture and civil engineering 2019/2/25 78 fig. 2 respondents knowledge about building performance evaluation fig. 3 no of interviewee that have carried out or been involved in building performance evaluation or research or published any article relating to building performance assessment. fig. 4 satisfaction level of interviewees with the building performance assessment practice in nigeria fig. 5 interviewees knowledge about the merits of using poe in building performance assessment building professionals knowledge of building performance analysis using poes in nigeria in fig. 2, majority of interviewees (n=76) stated that they are knowledgeable about building performance evaluation. this could be because majority of interviewees had at least a first-degree qualification and above and are building professionals. in fig. 3, majority of interviewees stated that they have not carried out or been involved in building performance evaluation, researched or published any article relating to building performance. the few interviewees who responded “yes” stated that they have been involved in poes of student’s hostel accommodation, motor park facilities assessment, and in some selected building estates in the country. they opined that only few poes seems to have been carried out in nigeria. this is evident in fig. 4 below were majority (n=80) of interviewees stated that they were dissatisfied with building performance assessment practice in nigeria in response to the benefits of using poe for building performance assessment, majority of interviewees stated that they were knowledgeable about the merits of using poe to assess a building’s performance. these gives concerns on why limited poes have been carried out in nigeria. possible reasons are stated in table 4. 10 79 journal of sustainable architecture and civil engineering 2019/2/25 building professionals perception of the benefits of and factors affecting the use of building performance assessment in nigeria in table 2, majority of interviewees stated that; improvement in building design following lessons learned from poes (79.5%) and forestalling future building failures (77.8%) were the major benefits of consistent building performance assessments using poes. this assertion is supported by the literature which suggested that poes may be beneficial in ascertaining the various causes of building collapse in nigeria. table 2 interviewees perspective of the benefits of a consistent building performance assessment practice in nigeria table 3 factors that could affect the sustainable practice of building performance assessment in nigeria benefits of building performance assessment frequency (n=117) percentage (%) improvement in building design following lessons learned 93 79.5 forestalling future building failures 91 77.8 enhancing building efficiency 38 32.5 improved functionality of the buildings 53 45.3 effective utilization of resources 57 48.7 regulation of architectural practice 75 64.1 expansion of knowledge base on building performance 69 59.0 improved structural stability and safety features in buildings 71 60.7 promote the review of building policies 46 39.3 improvement in service delivery 44 37.6 provision of new ways of solving building performance problems 34 29.1 in table 3, lack of policies that encourage poes, poor building laws enforcement, high cost of consultancy and professional fees and lack of interest by building professionals were leading factors limiting the sustainable practice of building performance assessment in nigeria. factors affecting building performance assessment frequency (n=117) percentage (%) lack of awareness of the benefits of poes 7 6.0 lack of policies that encourage poes 80 68.4 lack of interest by building professionals 55 47.0 high cost of consultancy and professional fees 69 59.0 poor continuous professional development of professionals 46 39.3 lack of database culture for archiving information 5 4.3 poor commitment to sustainability 43 36.8 poor clients and professionals relationship 47 40.2 lack of adequate information 48 41.0 lack of adequate experience in carrying out poes 59 50.4 non-involvement of building regulation authorities in construction 39 33.3 none usage of professionals in construction 37 31.6 government policies 48 41.0 poor building law enforcement 66 56.4 ignorance in the part of professionals and professional negligence 26 22.2 funds mismanagement 32 27.4 journal of sustainable architecture and civil engineering 2019/2/25 80 all interviewees stated that they will recommend the use of poe as a sustainable tool for building performance practice in nigeria because of the following reasons stated in table 4. from the systematic literature review, it is gathered that little or no attention is given to poe in nigeria unlike the greater attention given to it as a tool for assessing building performance at the global stage. highlighted were the definition, evolution, levels, dimensions, and benefits of poe as a sustainable tool for evaluating building performance by involving the owners, professionals, and occupants. poe serves the needs of the owners and it is critical that the building should be evaluated from time to time to ensure that it is serving its intended purposes. researchers also cautioned that poe methods should be simple and building typology specific. also highlighted was that industry split incentives, lack of supporting policies, and tools have inhibited adoption of poe processes especially in nigeria. from the interview responses, it is evident that building professionals in nigeria are aware of the benefits of using poes as a tool for assessing building performance. interviewees suggested that these benefits include; the use of poe data to improve buildings occupant’s health, safety, security, and functionality of a building. this indicates that interviewees understand that poe differs from other types of buildings’ similar to the position of some authors (jiboye, 2012; nwankwo et al., 2014) performance evaluations. however, majority (n=80) of interviewees were dissatisfied with building performance assessment practice in nigeria and recommended the use of poes as a sustainable tool for building performance analyses. most interviewees suggested that lack of policies that encourage the use of poes as well as possible high cost of engaging consultants are key factors that affect the sustainable practice of building performance assessment in nigeria and in developing countries at large. considering the frequency of building collapse in nigeria, most interviewees suggested that consistent building performance assessment using poes could be useful in providing evidence-based data that could help in the improvement of building design and polices to curb future building failures in nigeria. some interviewees also suggested that evidence-based data from poes could promote the review of building policies and expand building professional’s knowledge base on building performance analysis. furthermore, interviewees suggested that it will be useful to incorporate poes in building certification process in nigeria. nonetheless, the study findings generally support the argument that poes are important to improving user’s satisfaction in buildings which is similar to the position in some studies (adedayo and zubairu, 2013; olatunji, 2013 ), and establishing best practices and lessons learned in delivering building performance assessment in nigeria. reasons for recommending the use of poes in nigeria frequency percentage (%) to ascertain if the users of the space are satisfied with the building after occupancy 82 70.1 lessons learned would be useful in promoting design synergy in nigeria 54 46.2 it will promote knowledge on the proper use of building materials 66 56.4 improvement of poe know how 98 83.8 check reoccurrence of building failures in nigeria 102 87.2 it will create professional employment in the building sector 45 38.5 it will check professional negligence 92 78.6 it will check the possibility of building failure 102 87.2 table 4 reasons for recommending the use of poe as a sustainable tool for building performance practice in nigeria discussion conclusion this study appraised the dimensions and benefits of poe application as a useful tool in building performance assessment. the systematic literature review and responses from interviewees revealed that little or no attention is given to poe in developing countries like nigeria, unlike the greater attention given to it as a tool for assessing building performance at the global stage. the 81 journal of sustainable architecture and civil engineering 2019/2/25 results suggest that building occupants are a valuable source of information on building performance and that poe methods should be simple and building typology specific. in the nigerian context, the study findings suggest that the use of poes in building performance assessment could provide data driven information’s that would encourage guideline principles and design criteria to improve similar future projects to forestall building failures. interviewees recommended the incorporation of poes in building certification process in developing countries. the findings of this study are limited to 117 interviewees. interviewing a larger number of respondents including clients and building regulators as well as using questionnaires to gather the perception of policy makers may provide more insights regarding the sustainable use of poes for building performance assessment. in summary, this study supports the argument that poes are important to improving user’s satisfaction in buildings, and establishing best practices and lessons learned in delivering building performance assessment in nigeria. it is expected that the result of this study will encourage policy makers to consider regulations that enhances the uses of poes for building performance assessment to feed forward the positive and negative lessons learned to improve the design of current and future building developments in nigeria. referencesackley, a., teeling, c., atamewan, e. factors affecting the shortage and or provision of sustainable affordable housing in developing countries a case-study of cross river state, nigeria. journal of sustainable architecture and civil engineering, 2018; 27-38. https://doi.org/10.5755/j01.sace.22.1.20573 ackley, a., donn, m., thomas, g. the 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(pp. 23-34). united states of america: federal facilities council, the national academy press. 2002. yang, r., wang, l. development of multi-agent system for building energy and comfort management based on occupant behaviors. energy and buildings, january, 2013; 56: 1-7. https://doi.org/10.1016/j. enbuild.2012.10.025 yu, z., fung, b., haghighat, f., yoshino, h., morofsky, e. a systematic procedure to study the influence of occupant behavior on building energy consumption. energy and buildings, 2011; 43(6). https://doi. org/10.1016/j.enbuild.2011.02.002 zeiler, w., boxem, g. sustainable schools better than traditional schools? tvvl magazine, 2008; 24-31. zeiler, w., savanovic, p., quanjel, e. design decision support for the conceptual phase of the design process, 2007; 1-15. zimmerman, a., martin, m. post-occupancy evaluation: benefits and barriers. building research & information, 2001; 29(2): 168-174. https://doi. org/10.1080/09613210010016857 about the authors edidiong ukpong principal architect, directorate of physical planning university of uyo, akwa-ibom state, nigeria main research area lighting in buildings, indoor environmental quality, post occupancy evaluation address university of uyo, nigeria tel.: +2348060061292 email: edidiongukpong1983@gmail.com aniebietabasi ackley phd researcher faculty of architecture and design, school of architecture, victoria university of wellington, new zealand main research area sustainable architecture, building performance evaluation, indoor environmental quality and health architecture address 139 vivian street, te aro campus, wellington tel.: +642102850560 email: aniebietabasi.ackley@vuw.ac.nz https://doi.org/10.1016/j.envint.2015.09.010 https://doi.org/10.1016/j.envint.2015.09.010 https://doi.org/10.3390/atmos6101422 https://doi.org/10.3390/atmos6101422 https://doi.org/10.1016/j.buildenv.2009.02.007 https://doi.org/10.1016/j.buildenv.2009.02.007 https://doi.org/10.1016/j.proeng.2015.08.470 https://doi.org/10.1108/02632770610665775 https://doi.org/10.1108/02632770610665775 https://doi.org/10.1016/j.enbuild.2012.10.025 https://doi.org/10.1016/j.enbuild.2012.10.025 https://doi.org/10.1016/j.enbuild.2011.02.002 https://doi.org/10.1016/j.enbuild.2011.02.002 https://doi.org/10.1080/09613210010016857 https://doi.org/10.1080/09613210010016857 mailto:aniebietabasi.ackley@vuw.ac.nz journal of sustainable architecture and civil engineering 2016/3/16 6 *corresponding author: kyriakidis.andreas@ucy.ac.cy parametric numerical assessment of the thermal performance and environmental impact of an innovative masonry construction component http://dx.doi.org/10.5755/j01.sace.16.3.16174 andreas kyriakidis*, aimilios michael, rogiros illampas university of cyprus / department of architecture, nicosia, cyprus p.o. box 20537, 1678, nicosia, cyprus rogiros illampas university of cyprus, department of civil and environmental engineering, 75 kallipoleos st. p.o. box 20537, 1678 nicosia, cyprus received 2016/09/01 accepted after revision 2016/10/13 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 6-19 doi 10.5755/j01.sace.16.3.16174 © kaunas university of technology parametric numerical assessment of the thermal performance and environmental impact of an innovative masonry construction component jsace 3/16 the present study is part of a wider research program, which aims at the development of an innovative masonry construction system that integrates both environmental passive strategies and high energy efficiency. the paper focuses on the parametric computational investigation of the proposed system’s basic modular construction component. the thermal performance achieved by alternative geometries of the masonry unit, as well as the use of different constituent materials and insulation fillings, are further examined. the optimum solutions, in terms of thermal performance, were achieved by performing a series of numerical heat flux analyses on alternative proposals, arising from the combination of the above features. furthermore, the environmental impact, associated with the construction system, is assessed by estimating the total embodied energy of the modular component. it is concluded that the proposed system’s thermal performance relies primarily on the characteristics of the constituent mixture composing the modular masonry unit, the geometry of the unit and the use of insulation. in terms of environmental impact, both the constituent mixture used, and the type of insulation material installed, have a considerable impact on the end-product’s total embodied energy. keywords: innovative masonry construction component, high energy efficiency, parametric study, numerical assessment. 7 journal of sustainable architecture and civil engineering 2016/3/16 introduction masonry walls account for 29%-59% of thermal loss occurring in buildings and are thus, responsible for increased energy use and greenhouse gas emissions (balaras et al. 2000). furthermore, 13% of the energy consumed by buildings results from masonry manufacturing and construction processes (e.g. transportation of products, on-site equipment and human resources and on-site waste materials) (hammond and jones 2008a, b). in light of the above, there is a precipitated need for developing improved building construction systems that will be efficient in terms of energy performance and will require reduced natural and human resources for their production and construction (phocas et al. 2011, michael et al. 2012). within this context, michael et al. (2012) have conceived the idea of an innovative masonry component that offers customization potentials and can be used for the construction of structurally sound modular assemblies of variable forms. the proposed concept incorporates a series of passive design strategies, aiming at the improvement of indoor comfort conditions (philokyprou et al. 2013a, b), as well as at the minimization of energy consumption of the building envelope. depending on the prevailing climatic conditions and the occupants’ needs, different modular assemblies (architectural configurations) can be adopted to enhance thermal insulation (buffer zone), ventilation (building ventilation/stack effect), shading (suitable for different orientations) and integration of active solar systems (bougiatioti et al. 2015, michael et al. 2011, savvides et al. 2016). this study provides a state-of-the-art review on the development of novel walling systems and conducts a parametric analysis in order to assess the thermal performance and environmental impact of the proposed modular masonry unit. alternative geometries of the building component are taken into consideration and different constituent materials and insulation fillings are examined. in each case, the thermal properties of the resulting unit are determined through computational analysis and the environmental impact is estimated. comparable results are obtained and useful conclusions regarding the composition and geometry of the proposed unit are derived. furthermore, the study identifies areas that future research should address for the development of an integrated technical solution. review on the development of novel walling systems masonry materials include fired clay, concrete and calcium silicate brick units with variable properties (density = 450-2000 kg/m3; compressive strength = 2.5-100 mpa; thermal conductivity = 0.1-1.5 w/mk) (hendry 2001). due to the fact, that the characteristics of many conventional and traditional masonry materials (e.g. fired-clay bricks, concrete or earth-based blocks) are not adequate for achieving good energy performance (pacheco-torgal et al. 2015), considerable research efforts are currently in progress for upgrading existing masonry systems and for developing innovative energy-efficient walling components (miccoli et al. 2015, gakiet al. 2015, colombo et al. 2014). up to-date, emphasis has been placed on: (a) developing masonry units with optimized properties and (b) examining the use of parametric design and optimization algorithms for decreasing energy consumption. significant experimental work has been carried out aiming at the design of constituent mixtures suitable for the production of energy efficient, environmentally-friendly masonry units. velasco et al. (2016) considered the use of coffee ground wastes for the production of fired clay bricks. results show that the addition of coffee grounds can decrease thermal conductivity by up to 50%, without reducing compressive strength below 10 mpa. görhan and simsek (2013) investigated the effects of rice husk addition on the porosity and thermal conductivity of fired clay bricks. laboratory tests revealed that higher ratios of rice husk result to lower thermal conductivity coefficients and increased porosity and water absorption. sutcu (2015) performed experiments on fired clay bricks containing varying amounts of expanded vermiculite. this researcher notes that vermiculite can reduce density, improve porosity and decrease thermal conductivity by 30%, but may also lead to lower compressive strengths. wu et al. (2015) used shale along with building and industrial journal of sustainable architecture and civil engineering 2016/3/16 8 waste materials to manufacture fired hollow blocks. a compressive strength of 17.5 mpa and a u-value of 0.727 w/m2k was assessed for the units produced, indicating that the material developed is suitable for the construction of thermally efficient load-bearing walls. after conducting an experimental and numerical investigation on the properties of fired clay bricks containing organic matter, aouba et al. (2015) noted that the addition of wheat straw residue can improve thermal transmittance by more than 20%. bumanis et al. (2013) tested concrete mixtures incorporating expanded glass aggregates that can potentially be used for the fabrication of lightweight masonry blocks. although the compositions examined exhibited limited compressive strength (4.0-5.8 mpa), thermal conductivity values as low as 0.140 w/mk could be achieved. ashour et al. (2015) used soil stabilized with cement and gypsum and reinforced with natural straw fibers to produce sustainable unfired earth bricks. the experimental outcomes obtained indicate that the thermal conductivity of the constituent material could drop up to 0.310 w/mk for 3% fiber content. many studies focused on improving the thermal performance of walls by optimizing the geometric characteristics of the masonry units and/or by considering alternative construction patterns. sousa et al. (2014) conducted numerical analyses to determine the dimensions and the distribution of voids that would minimize the thermal transmittance of lightweight concrete blocks. even though the compressive strength of the optimized blocks did not fulfil code-prescribed requirements for load-bearing masonry, the researchers succeeded in designing a walling system with a u-value of 0.50 w/m2k. by performing finite element (fe) thermal analyses and by using the design of experiments and response surface methodology, sutcu et al. (2014) investigated how the geometry, material properties and temperature distribution affect the thermal behaviour of fired clay hollow blocks containing paper waste. reported data shows that modifying the distribution and size of the recesses within the blocks is adequate to attain u-values in the region of 0.50 w/m2k. diaz et al. (2014) also adopted fe simulation in combination with the response surface methodology to propose alternative geometrical configurations that would reduce the u-value of lightweight concrete hollow blocks. again research results highlight that a decrease of the recesses’ surface radiation emissivity can cause lower thermal transmittance. the influence of cavities on the dynamic thermal behaviour of fired clay bricks was studied in (arendt et al. 2011) through numerical and semi-analytical assessment methods. according to arendt et al. (2011), in order to achieve satisfactory thermal characteristics, the ratio of the total cavity area to the gross brick area should be between 30-65%, depending on whether the unit’s constituent mixture has low or high thermal conductivity. urban et al. (2011) investigated how the spatial arrangement of insulation layers influences the overall thermal resistance of concrete block masonry walls. it was found that thermal bridging through the solid webbing of the masonry units and the mortar joints can detrimentally affect thermal performance. having examined the influence of mortar joints on the thermal properties of single-leaf walls constructed of lightweight clay blocks, juárez et al. (2012) concluded that optimized geometric distribution of the masonry units and joints can lead to energy savings of up to 37%. promising solutions regarding the development of low-embodied-energy walling systems arise from studies focusing on interlocking building components. these systems present obvious advantages since they eliminate the use of jointing mortars and require less construction time (sharath et al. 2013). several researchers (e.g. thanoon et al. 2004, fay et al. 2014) developed self-aligned load-bearing blocks that can be interconnected by means of key connectors. a pilot application implemented at universiti putra malaysia (thanoon et al. 2004) verified that such mortarless masonry systems can reduce construction times by approximately 30%. a study by deepak (2012) indicates that the embodied energy involved in the dry construction of interlocking blocks can be up to 65% lower than that required for the erection of conventional fired clay brick masonry. 9 journal of sustainable architecture and civil engineering 2016/3/16 in addition to the above, efforts concerning the exploitation of parametric design in the framework of bioclimatic architecture have been made. more specifically, certain researchers (zemella 2011) considered the application of optimization algorithms based on artificial neural networks to decrease the energy consumption in buildings, while others (sarvani and kontovourkis 2013) used parametric design to integrate bioclimatic criteria in the design of high-rise habitation units. fig. 1 elevation and plan of the proposed modular brick assembly system within the framework hereby described, michael et al. (2012) adopted principles of the dynamic adaptive envelopes theory (velasco et al. 2015) to develop the novel idea of a multifunctional, customizable, modular brick assembly system (fig. 1). the general concept lies on the design of an innovative brick unit that consists of two distinct components: (a) the main body that enables interlocking without the use of mortar and (b) the outer leaf, which can be adjusted at different angles and tilts. depending on local environmental conditions and the particular needs of the building and its users, various different configurations and settings may be taken into consideration to improve the structure’s energy efficiency. this paper examines the effect of different geometrical configurations and constituent materials on the system’s thermal performance and embodied energy. the parametric analysis conducted in the framework of this study focuses on examining the thermal performance and environmental impact of the masonry unit’s main body. thermal performance was evaluated by computing the main body’s u-value, while the environmental impact was assessed by estimating the component’s embodied energy. in order to obtain comparable results, alternative geometries of the masonry unit’s main body were considered. the main body of the masonry unit is primarily composed of two components: (a) two interconnected longitudinal load-bearing sections and (b) a gap between them that can either act as an air gap, or may be filled with insulating material. the external dimensions of the main body are (height x length x width) 40 x 40 x 25 cm3. by variating the width of the gap, two different configurations (type a and b) are derived. the load-bearing sections of type a geometry are 6 cm wide and have a 13 cm gap between them. in type b geometry, the width of the load-bearing sections increases to 8 cm while the width of the gap reduces to 9 cm. the investigated geometries are presented in fig. 2. method fig. 2 axonometric views and horizontal sections of type a (a) and type b (b) geometrical variations of the modular building component (dimensions in cm) a b journal of sustainable architecture and civil engineering 2016/3/16 10 for the purposes of the parametric investigation, different constituent materials were assumed to compose the load-bearing sections of the unit. the selected constituent mixtures include materials currently used in practice for the production of masonry units (i.e. autoclaved aerated concrete (acc), fired clay and concrete) and materials used in research studies for the development of environmentally friendly building systems (i.e. unfired earth and lime). in addition, the effect of the gap between the load-bearing sections on the performance of the unit was examined by assuming that it can remain void or it can be filled with commonly used insulating materials i.e. polyurethane, polystyrene, rock wool and cork. the materials examined in this study are shown in table 1 along with the properties adopted for assessing the masonry unit’s energy performance and environmental impact. the values assigned to the materials’ densities and conductive coefficients are based on data given in the en1745 standard and on experimental results (ioannou et al. 2013, kyriakou 2014). embodied energy values were estimated using data available in the literature (hammond and jones 2008a). assessment of thermal performance to calculate the u-value of building members constructed of the masonry units under study, 2d numerical models were developed in matlab r2014a (fig. 3a, b). the models represent a plan-section of a wall 1.20 m long that is made of interlocking blocks laid without the application of jointing mortar. the simulated geometry is considered to be continuous throughout the height of the wall because the intended ‘stack-bond’ construction pattern involves placing one brick exactly above the other (fig. 1). the models were discretized into 3-noded triangular elements. adiabatic boundary conditions were assumed at the two side edges of the simulated wall. surface resistances were taken as rsi =0.13 m 2k/w at the wall’s interior and rse =0.04 m 2k/w at the wall’s exterior. the internal and external air temperatures were defined as tai = 22 °c and tae = 4 °c, respectively. the validity of the numerical analysis procedure was verified against the reference cases of the en1745 and en iso 6946 standards. after being validated, the models were used for performing fe analysis to simulate in 2d the heat transfer through the component. this enabled the accurate simulation of the heat flux through the complex geometry of the unit (fig. 3c, d). table 1 properties of the selected materials main body’s component material embodied energy density (kg/m3) conductive coefficient λ (w/mk)(mj/kg) (mj/m3) load-bearing sections aac 3.50 1750.0 500 0.012 fired clay 3.00 5700.0 1900 0.530 unfired earth (adobe) 0.45 585.0 1300 0.550 lime 0.85 1402.5 1650 0.650 concrete 0.95 1805 1900 0.900 infill insulation material polyurethane 72.00 2160.0 30 0.025 polystyrene 88.00 2640.0 30 0.030 rock wool 16.80 2352.0 140 0.035 cork 4.00 440.0 110 0.040 air gap gap 13cm 0.00 0.0 0 ra = 0.180 m 2k/w gap 9cm 0.00 0.0 0 ra = 0.175 m 2k/w 11 journal of sustainable architecture and civil engineering 2016/3/16 assessment of environmental impact embodied energy was hereby adopted as the primary environmental impact indicator because, contrary to embodied carbon measurements, it does not depend on the type of energy used during a product’s manufacturing process (hammond and jones 2008a). the embodied energy of the masonry component was estimated using the inventory of carbon and energy (ice) database of the university of bath (hammond and jones 2008a). the system boundaries taken from the ice are ‘cradle-to-gate’ and include all energy consumed until a product leaves the factory gate. in the ice database, the embodied energy values are given per unit mass (kg) for each material. the calculation of the mass (m) of each material for specific density (p) and volume (v) is given by the equation shown below in (1). fig. 3 geometry, boundary conditions (a) and fe mesh (b) of the 2d models developed in matlab r2014a. contour diagrams of temperature distribution (c) and heat flux (d) obtained from the analysis of a wall constructed of type a lime-based units that incorporate polystyrene core infill insulation the total embodied energy (ee) of each modular component under study was computed as the product between the energies embodied in the mass of the unit’s main body (eeb) and the insulation infill (eein). (1) (2) (4) (4) (3) m = p∙v ee = eeb + eein ee = eb∙mb + ein∙mb f = (u∙ee) / (max{u∙ee}) ee = eb∙pb∙vb + ein∙pin∙vin the embodied energy of the material used for the main body eeb for any certain case is the product between material’s energy eb (mj/kg) and mass mb (kg), i.e. pb∙vb. similarly, the embodied energy of the infill insulation material for any certain case eein is the product between material’s energy ein (mj/ kg) and mass min (kg), i.e. pin∙vin. the relative equations are shown below in (3) and (4). comparative factor estimation in order to enable comparison between the results yielded by the different cases examined, a factor (f) accounting for both the u-value (u) and the embodied energy (ee) was established. this is defined as: in the above equation, (u∙ee) is the product between the u-value and the embodied energy for any certain case and (max{u∙ee}) is the maximum product journal of sustainable architecture and civil engineering 2016/3/16 12 between the u-value and the embodied energy of all combinations examined. a masonry unit is considered to have good energy efficiency and environmental impact performance when both the u-value and embodied energy are low. hence, the optimum solution, in terms of geometrical configuration, constituent material and infill insulation material, is achieved when the minimum value of factor f is derived. results u-value the results obtained from the thermal numerical analyses are presented in table 2, which reports the u-values assessed by considering that the units are composed of different constituent materials, have different geometrical configurations (types a and b) and feature various types of core infills. results are compared against the 0.72 w/m2k limit value prescribed in the cyprus regulations for minimum energy efficiency requirements (2013) for new buildings. computed u-values range from 0.20 w/m2k to 2.09 w/m2k, depending on the constituent material, the geometry of the masonry unit and the type of insulation used. the majority of alternative combinations satisfy local code requirements (u-value < 0.72 w/m2k). in terms of material composition, the best results are achieved by the use of aac. u-values for aac units vary from 0.20 to 0.30w/m2k for units incorporating thermal insulation at their core and from 0.58 to 0.72 w/m2k for units with an air gap between their load-bearing sections. in all combinations examined, the thermal performance of aac units is at least 50% better compared to other constituent materials. this was, to some extent, expected due to the low conductive coefficient of aac. plain concrete, on the other hand, has rather poor thermal performance. u-values for concrete units with no insulation exceed 1.95 w/m2k. reducing the width of the load-bearing sections (type a), and introducing thermal insulation components in the case of concrete units, decreases the u-value up to 0.64w/m2k. minimal differences occur in the thermal performance of units composed by fired clay, unfired earth and lime. masonry units of these types, that feature an air gap at their central section, have u-values from 1.55 to 1.86 w/m2k. installing an insulating infill into the core of units composed by the aforementioned materials can yield u-values from 0.45 to 0.71 w/m2k. the results of the analysis give evidence that the use of insulating materials has a significant effect on the u-value achieved. filling the gap between the load-bearing sections of the unit with an insulation layer decreases the u-value by at least 50% compared to units with an air gap. it is worth pointing out that although the conductive coefficient of certain materials used as insulating infill differs by 60% (i.e. polyurethane has λ= 0.025 w/mk, while cork has λ= 0.040w/mk), corresponding u-values computed for the insulated masonry units differ only by 10-30%. the u-value of the masonry is also affected by the geometry of its components. insulated units of the type a configuration generally exhibit better thermal performance, than type b units. this table 2 u-value (w/m2k) for all the cases under study constituent material aac fired clay unfired earth lime concrete geometrical type a b a b a b a b a b infill insulation material polyurethane 0.20 0.24 0.45 0.55 0.46 0.56 0.51 0.62 0.64 0.77 polystyrene 0.22 0.26 0.48 0.58 0.49 0.59 0.54 0.65 0.66 0.80 rock wool 0.24 0.28 0.50 0.60 0.51 0.62 0.56 0.68 0.69 0.83 cork 0.26 0.30 0.52 0.63 0.53 0.65 0.59 0.71 0.71 0.86 reference air gap 0.72 0.58 1.72 1.55 1.74 1.57 1.86 1.71 2.09 1.96 * highlighted values correspond to u > 0.72 w/m2k 13 journal of sustainable architecture and civil engineering 2016/3/16 is because type a units have a larger distance between their load-bearing sections which allows for installation of thicker insulation layers. therefore, insulated type a units have u-values, which are approximately 15% lower than type b insulated units. the type b geometrical configuration generates better results in terms of thermal performance only in cases where no insulation is used. this may be attributed to the fact that the u-value of these units depends primarily on the thickness of its load-bearing sections, since the conductive coefficient of air does not change significantly for gap widths 9-13 cm. embodied energy the embodied energy values computed for the different types of masonry units examined are reported in table 3. results vary considerably, ranging from 12.8 to 189.4 mj, depending on the geometrical characteristics of the unit, the thermo-physical properties of the constituent material and the insulating filling component used. table 3 total embodied energy, ee (mj) for all the cases under study constituent material aac fired clay unfired earth lime concrete geometrical type a b a b a b a b a b infill insulation material polyurethane 77.5 75.2 163.6 183.4 52.1 43.3 69.9 65.6 78.7 76.7 polystyrene 86.2 81.2 172.3 189.4 60.8 49.3 78.6 71.7 87.4 82.7 rock wool 81.0 77.6 167.1 185.8 55.6 45.7 73.4 68.1 82.2 79.1 cork 46.2 53.5 132.3 161.7 20.8 21.6 38.6 44.0 47.4 55.0 reference air gap 38.2 48.0 124.3 156.2 12.8 16.0 30.6 38.4 39.4 49.5 results show that the lowest embodied energy values i.e. 12.8-60.8mj, can be obtained when unfired earth is used as the constituent material. this is due to the simple manufacturing processes involved in the fabrication of adobe bricks. the production of units composed of lime also has relatively low energy requirements, which range from 30.6 to 78.6 mj. the embodied energy values for units composed by aac and concrete are quite similar. units of this type, which do not feature an insulating filling have embodied energy values from 38.2 to 49.5 mj. the use of insulating materials along with aac, or concrete, increases the end product’s embodied energy to 46.2-87.4 mj. fired clay units have the highest embodied energy, as the firing procedure used when processing the raw materials significantly increases the energy required for production. in this case, the embodied energy of the units with no insulating filling is 124.3 and 156.2 mj for type a and b geometries respectively, while the use of polystyrene sections can increase the total embodied energy up to 189.4 mj. since the industrial procedures involved in the manufacturing of insulating materials (i.e. polyurethane, polystyrene, rock wool) result to high embodied energies, their use tends to increase the end product’s total energy requirements. an exception occurs when using certain types of insulation (e.g. cork) which have low environmental impact and can thus improve the unit’s thermal performance without significant increase in the end product’s total embodied energy. it is worth noting that in the case of fired clay units, the energy required for the production of the constituent material itself is significantly high and thus, the contribution of the insulation filling to the unit’s total embodied energy is rather low. comparative factor the comparative factors (f) estimated using (eq. 5) for all combinations of constituent material; geometrical configuration and infill insulation material are presented in table 4 and fig. 4. comjournal of sustainable architecture and civil engineering 2016/3/16 14 puted data shows that the optimum solution in terms of thermal performance and environmental impact is when the type a geometrical configuration is adopted, unfired earth is used as the constituent material and cork infill is inserted among the unit’s load-bearing sections for insulation. promising solutions are also obtained when units composed of aac and lime are insulated with cork. fired clay units exhibit rather poor performance due to the high embodied energy associated with the raw material’s fabrication process. the comparative estimated factors indicate that the use of concrete will not result to a thermally and environmentally efficient end-product. this is mainly attributed to the poor thermal performance of the constituent material. furthermore, results show that the best insulating solution in all cases is cork. although the conductive coefficient of cork is higher than that of polyurethane, polystyrene and rock wool the end-product’s total u-value achieved by this type of insulation does not significantly differ from that obtained when using the aforementioned materials. in addition, cork has much lower embodied energy, thus, reducing the environmental impact of the masonry unit. it is noted that the above comparisons account only for two factors associated with the overall behaviour of the masonry: (a) thermal performance and (b) environmental impact. in order to develop a reliable construction system, an integrated research approach must be adopted. this should investigate other important aspects, such as structural behaviour, fabrication process, building methodology etc. having said that, it can be argued that although aac and unfired earth appear to table 4 comparative factor (f) for all the cases under study. constituent material aac fired clay unfired earth lime concrete geometrical type a b a b a b a b a b infill insulation material polyurethane 0.065 0.075 0.305 0.415 0.100 0.100 0.149 0.169 0.209 0.245 polystyrene 0.080 0.088 0.339 0.452 0.122 0.120 0.176 0.194 0.241 0.274 rock wool 0.081 0.090 0.346 0.465 0.117 0.117 0.171 0.192 0.234 0.271 cork 0.050 0.066 0.286 0.423 0.046 0.058 0.094 0.129 0.140 0.195 reference air gap 0.114 0.116 0.882 1 0.092 0.105 0.236 0.271 0.341 0.402 * highlighted value corresponds to optimum combination (i.e. min{f}) fig. 4 graphic representation of the comparative factor (f) for all the cases under study. 15 journal of sustainable architecture and civil engineering 2016/3/16 produce thermally efficient and environmentally friendly units, these materials’ limited load-bearing capacity is a detrimental factor which may preclude their practical use. moreover, unfired earth tends to suffer from shrinkage upon drying (ioannou et al. 2013) something that introduces further complications to the potential fabrication process. the superior mechanical properties of limeand cement-based materials may compensate for their inferior thermal performance thus leading to more realistic solutions. discussionthe numerical data obtained in this study shows, that the thermal performance of walling systems is critically affected by: (a) the constituent mixture composing the masonry units (velasco et al. 2016, görhan and simsek 2013, sutcu 2015, wu et al. 2015, aouba et al. 2015, bumanis et al. 2013, ashour et al. 2015) and (b) the geometric configuration of the building component (sousa et al. 2014, sutcu et al. 2014, diaz et al. 2014, arendt et al. 2011, urban et al. 2011). the ratio between the core’s void and the brick’s total gross area is 52% for type a geometry and 36% for type b geometry. according to arendt et al. (2011), low-thermal-conductivity materials are required for optimizing the thermal properties of hollow brick units with cavity-to-gross-brick-area ratios between 30-45%. this justifies why only the use of aac resulted to u-values in the region of 0.7 w/m2k when no insulation was considered. based on the data reported in (arendt et al. 2011), it is envisaged that in order to achieve similar results with unmodified fired clay, unfired earth, lime and concrete mixtures, the cavity-to-gross-brick-area ratio should increase above 65%. in practice, this would be difficult to realize since it would drastically reduce the load-bearing sections of the unit. the heat flows computed by the fe analysis and the estimated u-values (fig. 3 and 4) indicate that the solid webs connecting the load-bearing sections of the brick influence significantly the overall thermal performance. this is because the aforementioned areas tend to act as thermal bridges. the effect is more profound when insulation layers are incorporated into the core of the brick. in this case, the thermal resistance of the brick’s constituent material is much lower than that of the insulation and a significantly higher heat transfer occurs at the areas of the webs. taking into account thermal bridging in 2d fe, the heat analysis yields more conservative estimates of u-value compared to code-prescribed analytical calculation methods, which ride on the 1d heat flow theory. relevant comments regarding the effect of solid webs on the heat flow generated at multicore and cut-web units have been made by urban et al. (2011), who examined the thermal performance of concrete block masonry. despite the presence of thermal bridges, the proposed masonry system can attain u-values from 0.20 to 0.90 w/m2k, given that thermal insulation materials are used. corresponding results found in the literature for similar types of constructions range from 0.43 to 0.72 w/m2k (wu et al. 2015, sousa et al. 2014, sutcu et al. 2014, diaz et al. 2014, arendt et al. 2011, urban et al. 2011). considering that u-value is the primary indicator for a building element’s thermal behaviour (bikas and chastas 2014a, b), it can be argued that the technical solution under development exhibits promising performance. the characteristics of the modular unit can be further improved by modifying the mix design of the constituent material (velasco et al. 2016, görhan and simsek 2013, sutcu 2015, wu et al. 2015, aouba et al. 2015, bumanis et al. 2013) so that thermal transmittance would not rely heavily on the provision of space for the installation of insulation. for this purpose, the introduction of additives such as natural fibers (ashour et al. 2015, ioannou et al. 2013) and lightweight aggregates may be considered. nevertheless, the constituent mixture must possess adequate fluidity to capture the complex shape of the modular unit and sufficient mechanical strength to ensure structural stability. moreover, the outcomes of the current study clearly show that the selection of an appropriate constituent mixture for the production of the modular units can significantly affect the building system’s embodied energy. this observation is in total agreement with the comments of other researchers who conclude that the total life cycle energy of a structure depends on the materials used for its construction (dixit et al. 2013, optis and wild 2010). as noted in (monteiro and freire journal of sustainable architecture and civil engineering 2016/3/16 16 2010, bribián et al. 2011) the use of firing manufacturing processes leads to considerably high embodied energy values. many studies emphasize on the energy savings achieved when using unfired earth instead of ceramics (pacheco-torgal and jalali 2012, shukla et al. 2009, reddy and jagadish 2003, udawattha and halwatura 2016, chrysostomou et al. 2015). however, questions are raised regarding the suitability of such mixtures for the production of load-bearing masonry units because unfired earth has low strength and is susceptible to moisture induced damage. the load-bearing capacity of aac is also rather limited due to the high porosity of the material, while the use of mechanical autoclaves can increase the environmental footprint of the final product. brick units composed of limeand cement-based composites can develop adequate stiffness and strength (kyriakou 2014, turgut 2012). although the energy involved in the fabrication of the two aforementioned binder materials is considerable, the total embodied energy of the mixture can be reduced by using industrial wastes as substitutes (e.g. fly ash, silica fume, etc.). lastly, calculations show that core insulation, apart from improving the thermal properties of the unit, it can increase of the construction system’s embodied energy. most researchers agree that the use of natural insulation materials such as cork can reduce environmental impact (lucas and ferreira 2010, bribián et al. 2011). nevertheless, it is noted that in areas where such materials are not available, the use of local resources can be considered so as to minimize the energy consumed during transportation (sierra-pérez 2016, chrysostomou et al. 2015, christoforou et al. 2016). conclusions a parametric study regarding the thermal performance and environmental impact of a novel masonry unit under development has been conducted. the effects of alternative geometries, material compositions and insulation solutions on the u-value and total embodied energy have been examined. u-value numerical analyses have shown that the proposed system’s thermal performance relies primarily on the characteristics of the constituent material composing the modular masonry unit. units composed of aac exhibit superior thermal properties, while minimal differences occur in the thermal behaviour of fired clay, unfired earth and lime units. the geometrical configuration of the unit also affects the u-value achieved, but to a lower extent. the installation of insulating material at the core of the unit improves energy performance by significantly reducing the overall u-value. according to the outcomes of the analyses, this reduction in u-value depends mainly on the thickness of the insulating layer, rather than on the type of insulation material used. in terms of environmental impact, both constituent mixture insulation materials used have a considerable effect on the end-product’s total embodied energy. bricks composed of unfired earth tend to be more environmentally friendly. limeand concrete-based mixtures can also form units with rather limited environmental impact, whereas the use of fired clay ceramic can significantly increase production energy requirements. most insulating materials hereby considered (i.e. polystyrene, polyurethane, rock wool) have themselves high embodied energies and can thus adversely affect the environmental characteristics of the end-product. nevertheless, certain types of insulation (i.e. cork) can offer better thermal performance without drastically increasing the unit’s environmental impact. a comparison of the results obtained indicates that thermally efficient units that have low embodied energy can potentially be produced using constituent mixtures composed of aac and unfired earth. however, further research should be conducted in order to thoroughly investigate all aspects relevant to the proposed system’s production method and practical application. the optimal form and size of the brick unit should be defined based on an integrated parametric analysis that will take into account bioclimatic, construction, structural, ergonomic and aesthetic aspects. alternative manufacturing methods should be examined and different constituent mixtures should be designed, based on the specific requirements imposed by the unit’s form. furthermore, laboratory tests should be performed to assess the thermo-physical, hygric and mechanical properties of the proposed masonry units. finally, the operational energy performance of the modular wall assembly system should be quantitatively evaluated and a detailed life cycle analysis should be performed. 17 journal of sustainable architecture and civil engineering 2016/3/16 the research described in this paper was carried out in the framework of postgraduate studies, as well as in the framework of the multidisciplinary research program “energy & environmental design of buildings”, funded by the university of cyprus, 2014-16. acknowledgment aouba, l., coutand, m., perrin, b. and lemercier, h., 2015. predicting thermal performance 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https:/doi.org/10.1016/j. enbuild.2011.10.006 andreas kyriakidis research associate, phd student university of cyprus, department of architecture main research area energy and environmental design, sustainability and construction design, innovative and sustainable construction components and materials, in situ and laboratory characterization of building materials, address 75 kallipoleos street, 1678, nicosia, tel. + 357 22 892977, e-mail: kyriakidis.andreas@ucy.ac.cy aimilios michael lecturer university of cyprus, department of architecture main research area energy and environmental design of buildings, sustainability and construction design, innovative and sustainable construction components and materials address 75 kallipoleos street, 1678, nicosia, tel. + 357 22 892977 e-mail: aimilios@ucy.ac.cy rogiros illampas post-doctoral researcher, adjunct faculty university of cyprus, department of architecture/department of civil and environmental engineering main research area experimental and numerical investigation of the structural response of masonry constructions, conservation of historic buildings, in situ and laboratory characterization of building materials address 75 kallipoleos street, 1678, nicosia, tel. + 357 22 894589, e-mail: rilamp01@ucy.ac.cy 31 journal of sustainable architecture and civil engineering 2016/1/14 *corresponding author: mindaugas.dauksys@ktu.lt influence of different curing conditions on density and compressive strength of hardened concrete with various types of chemical admixtures received 2016/04/10 accepted after revision 2016/05/15 journal of sustainable architecture and civil engineering vol. 1 / no. 14 / 2016 pp. 31-43 doi 10.5755/j01.sace.14.1.14479 © kaunas university of technology influence of different curing conditions on density and compressive strength of hardened concrete with various types of chemical admixtures jsace 1/14 http://dx.doi.org/10.5755/j01.sace.14.1.14479 introduction gintas brazas, mindaugas daukšys*, albertas klovas, jolanta šadauskienė kaunas university of technology, faculty of civil engineering and architecture studentu str. 48, lt-51367 kaunas, lithuania the research was made in order to determine the influence of the standard and non-standard curing conditions on the density and compressive strength of concrete specimens, when the mixture of concrete was modified by the use of different admixtures. from the same concrete mixture, part of the formed concrete specimens were cured according to the standard, another part according to non-standard method. according to the requirements of the en 12390-2:2009 standard, the specimens were cured for 28 days in water at the temperature of 20 ± 2ºc. another part of the specimens, which were covered by polyethylene covering, were cured for 28 days in a room with the temperature of 20 ± 4ºc and relative humidity of 60 ± 2 %. after that, comparison of density and compressive strength values of specimens, cured in different conditions, was made. it was found, that the density of specimens cured by standard way was higher than the density of specimens which were cured in non-standard way, chemical admixture type did not influence the results. the trends of compressive strength of concrete specimens, cured by different methods, depended on the type and percentage of chemical admixture in the mass of cement. keywords: curing conditions, chemical admixture, hardened concrete, density, compressive strength. nowadays, the concrete admixtures are widely used in the construction projects. various types of chemical admixtures are used to improve concrete’s construction properties: workability, pumpability, setting properties, the mechanical performance, the durability (such as freeze thaw resistance and the shrinkage properties) and others (such as corrosion inhibitors and colouring agents etc.) (plank et al. 2015; albayraka et al. 2015; lazniewska-piekarczyka, 2013). the structure of hydration products generated during the cement’s hydration, as well as the use of different concrete admixtures have influence on the formation of concrete structure during the solidification process. atis, 2005 investigated the strength properties of high-volume fly ash (hvfa) roller compacted and superplasticized workable concrete cured at moist and dry curing conditions. concrete mixtures made with 0%, 50% and 70% replacement of normal portland cement (npc) with two difjournal of sustainable architecture and civil engineering 2016/1/14 32 ferent low-lime class f fly ashes were prepared. water–cementious material ratios ranged from 0.28 to 0.43. the influence of moist and dry curing conditions on the high-volume fly ash (hvfa) concrete system was assessed through a proposed simple efficiency factor. the study showed, that producing high-strength concrete was possible with high-volume fly ash content. loss on ignition (loi) content increased the water demand of fresh concrete. hvfa concrete was found to be more vulnerable to dry curing conditions than was npc concrete. zhao et al. 2012 studied the effect of initial water-curing period and curing condition on properties of self-compacting concrete (scc). six different curing regimes were applied to the specimens, the first of which the specimen was stored under initial water-curing periods of 3, 7, 14 days, in the remaining three regimes, the specimens were continuous full water (fw) curing condition, continuous full standard (fs) curing condition and continuous full room (fr) curing condition. the mechanical properties of scc under different initial water-curing period and curing condition were tested. the test results showed that it is necessary to apply water-curing to scc for the initial 7 days period to expose the pozzolanic activity, scc under fr curing condition has a higher compressive strength, flexural strength, a lower carbonation depth and chloride ion diffusion coefficient than scc under fs, fw curing condition. tan and gjorv, 1996 studied the effect of curing conditions on strength and permeability of concrete. test results showed that after 3 and 7 days moist curing only the concretes with w/c ratios equal to or less than 0.4 were accepted, while after 28 days of moist curing however, even the concrete with w/c of 0.6 could be accepted. silica fume has a significant effect on the resistance to water penetration. for the concretes both with and without silica fume and with w/c + s of 0.5, the 28-day compressive strengths of 3 and 7 days moist curing were higher than those of 28 days moist curing, and the silica fume concrete seemed to be less sensitive to early drying. the curing temperatures did not affect the water penetration of concrete, but affected the chloride penetration and compressive strength of concrete significantly. ling and teo, 2011 investigated the engineering properties of the bricks. among the studied properties were: hardened concrete density, compressive strength and water absorption of the expanded polystyrene (eps) rice husk ash (rha) concrete bricks. four types of curing conditions were employed in this study: full water curing, air dry curing, 3-day curing and 7-day curing. it was found that the properties of the bricks are mainly influenced by the curing condition used. full water curing was the most effective method of curing. it produced the highest level of compressive strength and the lowest value of water absorption. on the contrary, air-dry curing produced the lowest level of compressive strength and the highest level of water absorption. gayarre et al. 2014 investigated the influence of different curing conditions on the compressive strength of recycled aggregate concrete. the concrete specimens were exposed to two different environments (standard curing and open-air curing) for 28 days. the results showed that the 7-days strength increases with the percentage of replacement, being this behaviour more evident for the standard curing environment. the 28-days compressive strengths of concretes with recycled aggregates were found similar to the ones obtained with natural aggregate when the standard curing environment was considered. however, the recycled aggregate concrete specimens lost up to the 20% of their compressive strength when they were cured in open-air conditions. ling et al. 2012 studied the performance of self-compacting glass concrete (scgc) after exposure to four elevated temperatures of 300ºc, 500ºc, 600ºc and 800ºc. the influence of curing condition on the high temperature performance of scgc was also investigated. the test results indicate that regardless of the exposure temperature, all the water cured specimens had higher residual strengths and mass losses while the water porosity and water sorptivity values were lower as compared to the corresponding air cured specimens. atis et al. 2005 studied compressive strength of silica fume concrete under dry and wet curing 33 journal of sustainable architecture and civil engineering 2016/1/14 conditions. three cubic specimens produced from fresh concrete were demoulded after a day; then, they were cured at 20±2 ºc with 65% relative humidity (rh), and three other cubic specimens were cured at 20±2 ºc with 100% rh until the specimens were used for compressive strength measurement at 28 days. the comparison was made on the basis of compressive strength between silica fume concrete and control portland cement concrete. the comparisons showed that compressive strength of silica fume concrete cured at 65% rh was influenced more than that of portland cement concrete. it was found that the compressive strength of silica fume concrete cured at 65% rh was, at average, 13% lower than that of silica fume concrete cured at 100% rh. the increase in the water–cementitious material ratios makes the concrete more sensitive to dry curing conditions. the influence of dry curing conditions on silica fume concrete was marked as the replacement ratio of silica fume increased. the strength development and durability of concretes with silica fume (sf) and blast furnace slag (bfs) are reported to be critically dependent on the extent of curing and curing conditions (turkmen, 2003). the specimens were cured in different curing regimes for periods varying from 28, 75, 150, to 400 days before exposure to the experiments. it was observed that the specimens with sf%10 + bfs%20 and 0.35 water–binder ratios had the highest compressive strength and ultrasonic pulse velocity (upv), the lowest capillarity coefficient and the appearing porosity. as a result, it can be concluded that the mineral admixtures improved the compressive strength, upv, capillarity coefficient and appearing porosity. khatib and mangat, 1999 examine the influence of one type of sp on porosity and pore size distribution under different curing regimes. paste specimens with and without sp were prepared at constant water to cement ratio of 0.45. specimens were cured for 28 days and some for six months. specimens were exposed to high temperature (45ºc) and normal temperature curing (20ºc) and also subjected to different relative humidities (̴100%, 55% and 25%). the results show that the inclusion of sp decreases the total intruded pore volume of paste. the dominant pore diameter, however, does not seem to be affected and the percentage of pores smaller than 100 nm increases in the presence of sp. according to authors (ali et al. 2013) when the polycarboxylate-type admixture and the cement were compatible, the early strength was dependent on the type of admixture whereas at the ages beyond 7 days the strength became independent of the admixture type. the admixture causing the highest slump loss caused the highest concrete strength at early ages. the mortars containing vma developed 6% to 16% lower compressive strength than those without any vma (saric-coric et al. 2003). however, the compressive strength of mixtures made with polymelamine sulfonate (pms) was higher that corresponding mixtures made with polynaphtalene sulfonate (pns). this was partially due to the lower capillary porosity. also, the c-s-h gel structure was more dense and compact in cement paste made without any vma, indicating more advanced cement hydration that in the case of vma mixtures where the structure was rather heterogeneous. the type of sp is very important because of the parameters size of hpscc air pores (łazniewska-piekarczyk, 2013). in case of hpscc with “air-entraining” sp, the content of the air pores is higher only by 1.46%, but the specific surface of the air voids, air voids spacing factor and content of the air voids with diameters less than 300 µm are much higher. the type of aea is very important due to the efficiency. the analysis of the results shows that the type of aea significantly affects the total air content in hardened hpscc. other parameters of hpscc porosity, with different types of aea, are similar. however, depending on afa type, more or less frequently there are the smallest air voids. according to the standard curing method, specimens were cured for 28 days in water of temperature 20±2ºc, after they were removed from the forms. later on, certain designed values are deterjournal of sustainable architecture and civil engineering 2016/1/14 34 mined. during the construction process, on the building site, when monolithic concrete structures are made (for example, monolithic slabs), concrete surfaces are covered by certain materials (for example, polyethylene covering) during the curing process. this is done in order to lower the process of moisture remove from the concrete. outside temperature, relative humidity and other factors are also influencing the curing process. in this study, from the same concrete mixture, part of the formed concrete specimens were cured according to the standard, another part according to non-standard method (when concrete specimens, covered by polyethylene covering, were cured for 28 days in a room). later on, comparison of density and compressive strength values of specimens cured in different conditions was made. the aim of this work is to determine influence of standard and non-standard curing conditions on the density and compressive strength of concrete specimens, when the mixture of concrete is modified by the use of different admixtures. portland cement cem ii/a-ll 42.5 r (ma) (a) (jsc akmenės cementas production) was used for the test. physical, mechanical properties and chemical composition of portland cement cem ii/ a-ll 42.5 r are given in table 1. washed sand from “kvesu quarry“ with the fractions of 0/1 and 0/4, bulk densities of 1521 kg/m3 and 1711 kg/m3 and fineness modules of 1.78 and 2.62 was used as fine aggregates. gravel with the fraction of 4/16 and bulk density of 1657 kg/m3 was used as the coarse aggregate. granulometric composition of aggregates is conducted according to en 12620:2013 and presented in table 2. in this investigation, concrete admixtures were chosen, which are widely used in the concrete monolithic projects. concrete mixtures were prepared by using combination of two different chemical admixtures, e.g. sp and afa, sp and vma, sp and aea. the description of chemical admixture (basf construction chemicals italia spa) used in this study is indicated in table 3. the amount of concrete’s admixture was calculated as % of cement mass. methods table 1 physical, mechanical properties and chemical composition of portland cement cem ii/a-ll 42.5 r (ma) (a) specific surface area, m2/kg 410 particle density, kg/m3 3110 dry bulk density, kg /m3 1220 water demand for normal consistency (by vicat), % 26,5 volume stability, mm 0,8 initial setting time, min. 195 compressive strength after 2 days / after 28 days, mpa 27.1/54.0 loss on ignition, % (masės) 5.05 insoluble materials, % (masės) so3, % 2.48 cl-, % 0.015 alkalis, calculated by na2o equivalent, % <0.72 table 2 granulometric composition of aggregates radius of the sieve’s mesh, mm the amount of poured out material, % sand fraction 0/1 sand fraction 0/4 gravel fraction 4/16 32.0 100.0 16.0 95.6 8.0 100.0 100.0 34.9 4.0 100.0 97.8 2.9 2.0 99.9 86.3 0.7 1.0 94.8 68.5 0.7 0.500 39.1 37.9 0.7 0.250 3.0 4.9 0.7 0.125 0.3 1.2 0.7 0 0.2 0.1 0.1 35 journal of sustainable architecture and civil engineering 2016/1/14 the concrete mixtures were prepared in 3 minutes by two stages in laboratory, by forced type concrete mixer zyklos rotating pan mixer zz 75 he. during the first stage, cement, aggregates and 2/3 of water were poured into the moistened mixer and mixed for 2 minutes. while during the second phase, the remaining amount of water was poured with concrete admixture and concrete mixture was mixed for 1 minute. during the research, dry aggregates were used for concrete mixtures. cement and aggregates were dosed by weight while water and chemical admixture were dosed by volume. when preparing the concrete mixture, 90 % of water was instantly poured to the mix. super-plasticizing admixture was mixed with 10 % of water and poured into the mixer. remaining admixtures were dozed directly to the mix. the compositions of concrete mixtures used in this research are presented in table 4. table 3 description of chemical admixture used for concrete mixture preparation name glenium sky 628 rheomix 880 rheomatrix 100 micro air g (lp) admixture super-plasticizer anti-foaming viscosity modifying air-entraining marking sp afa vma aea compound-based polycar boxylate propoxylate– etoxylate synthetic –copolymer modified –resin recommended dosage, % 0.6 – 1.4 0.1 – 0.3 0.1 – 1.5 0 – 0.3 density, g/cm3 1.06 – 1.10 0.97 ± 0.02 1.00 – 1.02 0.98 – 1.04 viscosity, mpa×s – <600 – – ph – – 6 – 9 9 – 11 chloride quantity, % <0.1 – <0.1 <0.01 alkali quantity, % <2.5 – – – table 4 composition of concrete mixtures materials u ni t concrete mixture compositions marking. amount of materials for 1m3 concrete mixture ba4-0-ba4-6 ba5-0-ba5-6 ba6-0ba6-6 ba7-0-ba7-6 cem ii/a-ll 42,5 r (ma)(a) kg 380 380 380 380 water l 178 178 178 178 water and cement ratio 0.54 0.54 0.54 0.54 sand fraction 0/1 kg 286 286 286 286 sand fraction 0/4 kg 574 574 574 574 gravel fraction 4/16 kg 985 985 985 985 super-plasticizer (ca1) % 0.6÷1.8 1.4 1.4 1.4 air voids remover (ca2) % – 0.05÷0.3 – – viscosity modifier (ca3) % – – 0.1÷1.1 – air entertainer (ca4) % – – – 0.05÷0.3 the concrete specimens, cubes of 100 × 100 × 100 mm dimensions size, were formed in metal forms and compacted on vibrational table. the specimens were kept for 20 hours in forms at the temperature of 20 ± 2°c. when specimens were removed from the forms, they were cured in different conditions: a) the specimens were stored in water for 28 days at the temperature of 20 ± 2°c (standard method); b) specimens were covered by polyethylene covering and stored in a room for journal of sustainable architecture and civil engineering 2016/1/14 36 28 days with the temperature of 20 ± 4ºc and relative humidity of 60 ± 2 % (non-standard method). the density of hardened concrete was determined according to standard en 12390-7:2009. the specimen was tested after curing in water; when 2-4 hours were passed after specimen was removed from water or it was taken from the curing room. the volume was calculated from the regular shape of the specimen size. the compressive strength of hardened concrete specimens was determined according to standard en 12390-3:32009. scale coefficient of specimens 100×100×100 mm α equal 0.95. specimens surface flatness and sides perpendicularity with noticed base satisfied standard en 12390-1:2012 requirements. microsoft excel program was used for identifying the best dependence of the dispersion of the density and comprehensive strength values of hardened concrete and equation’s empirical coefficients values. correlation coefficient (pirson), which is evaluating the strength of linear relationship, was calculated according to coefficient of empirical equation. the closer correlation coefficient is to 1, the better representation of the dispersion of values in the curve. according to the obtained correlation coefficient, it was determined which equation describes the best distribution of statistical data. the influence of super-plasticizing admixture (sp) on concrete specimens’ density and compressive strength under different curing conditions the dependence of density and compressive strength of hardened concrete (mixture’s compositions ba4-0–ba4-6) from the amount of sp admixture in % of cement mass, under different curing conditions is presented in fig. 1a and 1b. the fig. 1a shows, that the trends of density of concrete specimens were similar even after curing them under different conditions. when the amount of sp admixture was increased from 0.6 to 1.8 % of the cement mass, the average density of specimens cured by standard method was in the range of 2370÷2410 kg/m3, and the average density of specimens cured by non-standard method was in the range of 2310÷2400 kg/m3, then water and cement ratio was constant and equal to 0.54. the same average density (2400 kg/m3) of the specimens which were cured under different conditions was obtained with sp admixture of 1.4 % of the cement mass. then the amount of sp admixture was increased from 0.6 to 1.8% of the cement mass, the average density of specimens cured by standard method was increased by 1.02 times, and the average density of specimens cured by non-standard method was increased by 1.03 times. when the amount of sp admixture was increased from 0.6 to 1.8 % of the cement mass (figure 1b), the average compressive strength of specimens cured by standard method was in the results fig. 1 the hardened concrete density (a) and compressive strength (b) depending on the amount of sp a b 37 journal of sustainable architecture and civil engineering 2016/1/14 range of 49.6÷53.3 mpa, and the average compressive strength of specimens cured by non-standard method was in the range of 45.0÷56.7 mpa. then the amount of sp admixture was exceeding 1.2% of the cement mass, the average compressive strength of specimens cured by non-standard method was 1.09 times higher then the average compressive strength of specimens cured by standard method. then the amount of sp admixture was exceeding 1.4% of the cement mass, water separation from the mixture was observed, which could have influenced the compressive strength of concrete specimens. table 5 the dependence of dispersion of data curing method properties of hardened concrete equation coefficients value of equation r-squared value correlation coefficient r connection between variablesa b c nonstandart density y = a·x2+b·x+c 12,22 34,00 2301,0 0,587 0,76 strong compres. strength y = a·x2-b·x+c 11,15 15,81 50,26 0,914 0,96 strong standart density y = -a·x2+b·x+c 17,64 76,54 2332,4 0,596 0,77 strong compres. strength y = a·x2-b·x+c 1,91 3,97 52,50 0,010 0,10 very weak from table 5 we can see, that values of dispersion of dependence of hardened concrete density and compressive strength on amount of sp admixture under different curing conditions can be described by polynomial dependencies. the values of correlation coefficient were in the range from 0.10 till 0.96. the influence of anti-foaming admixture (afa) on concrete specimens’ density and compressive strength under different curing conditions the dependence of density and compressive strength of hardened concrete (mixture’s compositions ba5-0–ba5-6) from the amount of afa admixture in % of cement mass, under different curing conditions is presented in fig. 2a and 2b. from fig. 2a we can see, that the trends of density of concrete specimens were similar even after curing them under different conditions. when the amount of afa admixture was increased from 0 to 0.3 % of the cement mass, the average density of specimens cured by standard method was in the range of 2400÷2420 kg/m3, and the average density of specimens cured by non-standard method was in the range of 2350÷2400 kg/m3. it was observed, that the density of specimens cured by standard method was 1.02 times higher then the density of specimens cured by non-standard method. when the amount of afa admixture was increased from 0 to 0.3 % of the cement mass, the average density of specimens cured by standard method was increased from 2400 kg/m3 till 2410 kg/m3, and the average density of specimens cured by non-standard method was decreased from 2400 kg/m3 till 2360 kg/m3. the amount of sp admixture was constant and equal to 1.4 % of the cement mass. according to author (lazniewska-piekarczyka, 2013) the effects of modification by afa of high performance self-compacting concrete (hpscc) depend on their type very significantly. the type of afa impacts very significantly on the air content of hpscc. in case of one afa type, it is significant increase in diameter of flow while reducing the air content in hpscc. other type of afa does not improve the workability and does not cause a significant reduction in the air content in hpscc. the type of afa is also important because of the parameters values of the air voids of hpscc. depending on the type of afa, the change of the size and content of pores in hpscc differs. the fig. 2b shows, that the trends of compressive strength of concrete specimens, cured under different conditions, depended on the amount of admixture in % of cement mass. when the amount of afa admixture was 0.05 % of the cement mass, the average compressive strength journal of sustainable architecture and civil engineering 2016/1/14 38 of specimens cured by standard method was 1.26 times higher, and the average compressive strength of specimens cured by non-standard method was 1.08 times higher, compared with a control specimen without afa admixture. when the amount of afa admixture was increased to 0.3 % of the cement mass, the average compressive strength of specimens cured by standard method was 1.09 times lower, and the average compressive strength of specimens cured by non-standard method was 1.03 times lower. then the amount of afa admixture was exceeding 0.15% of the cement mass, the average compressive strength of specimens cured by non-standard method was 1.04 times higher then the average compressive strength of specimens cured by standard method. when the amount of afa admixture was increased from 0.05 to 0.3 % of the cement mass, the average compressive strength of specimens cured by standard method was in the range of 56.7÷51.9 mpa, and the average compressive strength of specimens cured by non-standard method was in the range of 54.8÷53.2 mpa. the most rational amount of afa admixture (for the analysed mixture) could be 0.15% of the cement mass, when compressive strength of specimens cured by standard method is considered. fig. 2 the hardened concrete density (a) and compressive strength (b) depending on the amount of afa a b table 6 the dependence of dispersion of data curing method properties of hardened concrete equation coefficients value of equation r-squared value correlation coefficient r connection between variablesa b c nonstandart density y = a·x2-b·x+c 198,38 199,33 2396,3 0,406 0,64 quiet compres. strength y = -a·x2+b·x+c 153,31 52,25 51,19 0,516 0,72 strong standart density y = -a·x2+b·x+c 486,43 132,34 2407,2 0,086 0,29 weak compres. strength y = -a·x2+b·x+c 301,14 97,08 48,14 0,479 0,69 quiet from table 6 we can see, that values of dispersion of dependence of hardened concrete density and compressive strength on amount of afa admixture under different curing conditions can be described by polynomial dependencies. the values of correlation coefficient were in the range from 0.29 till 0.72. the influence of viscosity modifying admixture (vma) on concrete specimens’ density and compressive strength under different curing conditions the dependence of density and compressive strength of hardened concrete (mixture’s compositions ba6-0–ba6-6) from the amount of vma admixture in % of cement mass, under different curing conditions is presented in fig. 3a and 3b. 39 journal of sustainable architecture and civil engineering 2016/1/14 a b the fig. 3a shows, that the trends of density of concrete specimens were not analogical after curing them under different conditions. when the amount of vma admixture was increased from 0 to 1.1 % of the cement mass, the average density of specimens cured by standard method was in the range of 2370÷2410 kg/m3, and the average density of specimens cured by non-standard method was in the range of 2350÷2400 kg/m3. the amount of sp admixture was constant (1.4 % of the cement mass). when the amount of vma admixture was increased from 0.1 to 1.1 % of the cement mass, the average density of specimens cured by standard method was decreased from 2410 kg/m3 till 2370 kg/m3. the average density of specimens cured by non-standard method, with ca3 admixture from 0.1÷0.5% of the cement mass, was decreased from 2400 kg/m3 till 2350 kg/m3. when the amount of vma admixture was increased till 1.1 % of the cement mass, the average density of specimens cured by non-standard method was increased from 2350 kg/m3 till 2360 kg/m3. the same average density (2390 kg/m3) of specimens, cured by different conditions, was obtained with vma admixture of 0.7% of the cement mass. according to author (lazniewska-piekarczyka, 2013) vma, depending on the type of afa and vma, has more or less beneficial effect on the air content in hpscc. the use of one type of vma does not increase the air content in hpscc with afa. another type of vma significantly increases the air content in hpscc with afa. vma affects the air content in hpscc, also depends on the type of afa. depending on the type of vma and afa, a very different change in the characteristics of the air voids is observed. in one case, vma does not change the characteristics of the porosity, in the second, significantly affects. the fig. 3b shows, that the trends of compressive strength of concrete specimens, cured under different conditions were not identical. when the amount of vma admixture was 0.1 % of the cement mass, the average compressive strength of specimens cured by standard method was 1.24 times higher, and the average compressive strength of specimens cured by non-standard method was 1.05 times higher, compared with a control specimen without vma admixture. when the amount of vma admixture was increased from 0.1 to 0.5 % of the cement mass, the average compressive strength of specimens cured by standard and non-standard methods were slightly lower, respectively from 55.6 mpa till 54.7 mpa and from 53.0 mpa till 51.2 mpa. when the amount of vma admixture was increased from 0.5 to 1.1 % of the cement mass, the average compressive strength of specimens cured by standard method was decreased from 54.7 mpa till 51.4 mpa, and the average compressive strength of specimens cured by non-standard method was increased from 51.2 mpa till 55.2 mpa. then the amount of vma admixture was exceeding 0.6% of the cement mass, the average compressive strength of specimens cured by non-standard method was 1.07 times higher than the average compressive strength of specimens cured by standard method. the most rational amount of ca3 admixture (for the analysed mixture) could be 0.5% of the cement mass, when compressive strength of specimens cured by standard method is considered. fig. 3 the hardened concrete density (a) and compressive strength (b) depending on the amount of vma journal of sustainable architecture and civil engineering 2016/1/14 40 from table 7 we can see, that values of dispersion of dependence of hardened concrete density and compressive strength on amount of vma admixture under different curing conditions can be described by polynomial dependencies. the values of correlation coefficient were in the range from 0.21 till 0.67. the influence of air-entraining admixture (aea) on concrete specimens’ density and compressive strength under different curing conditions the dependence of density and compressive strength of hardened concrete (mixture’s compositions ba7-0–ba7-6) from the amount of aea admixture in % of cement mass, under different curing conditions is presented in fig. 4a and 4b. table 7 the dependence of dispersion of data curing method properties of hardened concrete equation coefficients value of equation r-squared value correlation coefficient r connection between variablesa b c nonstandart density y = a·x2-b·x+c 34,30 46,32 2377,0 0,046 0,21 weak compres. strength y = a·x2+b·x+c 2,325 0,821 51,51 0,448 0,67 quiet standart density y = -a·x2+b·x+c 63,67 36,41 2406,1 0,432 0,66 quiet compres. strength y = -a·x2+b·x+c 15,57 16,89 49,55 0,230 0,48 weak fig. 4 the hardened concrete density (a) and compressive strength (b) depending on the amount of aea a b from fig. 4a we can see, that the trends of density of concrete specimens were similar after curing them under different conditions. when the amount of aea admixture was increased from 0 to 0.3 % of the cement mass, the average density of specimens cured by standard method was decreased from 2400 kg/m3 till 2380 kg/m3. the average density of specimens cured by non-standard method was decreased from 2400 kg/m3 till 2350 kg/m3. the amount of sp admixture was constant (1.4 % of the cement mass). it was observed, that when the amount of aea admixture was increased from 0.05 to 0.3 % of the cement mass, the average density of specimens cured by standard method was 1.01 times higher compared with average density of specimens cured by non-standard method. the fig. 4b shows, that the trends of compressive strength of concrete specimens, cured under different conditions were similar. air-entraining admixture, taking into account it’s intended use, is increasing porosity of hardened concrete and decreasing it’s density. when the amount of aea 41 journal of sustainable architecture and civil engineering 2016/1/14 admixture was 0.05 % of the cement mass, the average compressive strength of specimens cured by standard method was 1.18 times higher, and the average compressive strength of specimens cured by non-standard method was 1.12 times higher, compared with a control specimen without aea admixture. when the amount of afa admixture was increased to 0.25 % of the cement mass, the average compressive strength of specimens cured by non-standard method was almost the same as the average compressive strength of specimens cured by standard method. when the amount of aea admixture was increased from 0.05 to 0.15 % of the cement mass, the average compressive strength of specimens cured by standard and non-standard methods was decreasing, respectively from 53.1 mpa till 52.2 mpa and from 56.6 mpa till 55.4 mpa. it was observed, that the average compressive strength of specimens cured by non-standard method was 1.06 times higher than the average compressive strength of specimens cured by standard method. when the amount of aea admixture exceeded 0.2 % of the cement mass, the average compressive strength of specimens cured by standard method was higher then the average compressive strength of specimens cured by non-standard method. table 8 the dependence of dispersion of data curing method properties of hardened concrete equation coefficients value of equation r-squared value correlation coefficient r connection between variablesa b c nonstandart density y = a·x2-b·x+c 612,7 284,5 2394,1 0,195 0,44 weak compres. strength y = -a·x2+b·x+c 235,0 59,05 51,98 0,648 0,80 strong standart density y = -a·x2+b·x+c 334,3 11,84 2400,4 0,320 0,57 quiet compres. strength y = -a·x2+b·x+c 284,8 92,95 46,50 0,609 0,78 strong from table 8 we can see, that values of dispersion of dependence of hardened concrete density and compressive strength on amount of afa admixture under different curing conditions can be described by polynomial dependencies. the values of correlation coefficient were in the range from 0.44 till 0.80. the results obtained showed that the specimens without air-entraining admixture show a deterioration of mechanical properties after the freeze–thaw test (łazniewska-piekarczykb, 2013). however, the inclusion of air bubbles benefits the behaviour of concrete against freeze–thaw cycles so even better mechanical properties after the test were observed. this anomalous behaviour is because the cement hydration process continues over the freeze–thaw tests, closing the pore structure. this aspect has been confirmed with the dta and tg tests performed. 1 regardless of the type of the chemical admixture, which was used to modify concrete mix-ture, the 28-day density of specimens cured by standard method (in water at the temperature of 20 ± 2ºc) was higher by several % comparing with the 28-day density of specimens cured by non-standard method (in a room with the temperature of 20 ± 4ºc and relative humidity of 60 ± 2 %). 2 the tendencies of 28-day compressive strength of concrete specimens cured by standard and non-standard methods depended on the type and percentage of the chemical admixture: _ when the amount of sp admixture exceeded 1.2 % of the cement mass, the average compressive strength of specimens cured by non-standard method was 1.09 % higher than the average compressive strength of specimens cured by standard method; conclusions journal of sustainable architecture and civil engineering 2016/1/14 42 references _ when the amount of afa admixture exceeded 0.15 % of the cement mass, the average compressive strength was 1.04 % higher; _ when the amount of vma admixture exceeded 0.6 % of the cement mass, the average compressive strength was 1.07 % higher; _ when the amount of aea admixture reached 0.25 % of the cement mass, the average compressive strength of specimens cured by non-standard method was almost equal to the average compressive strength of specimens cured by standard method. 3 according to the obtained correlation coefficient, it was determined that polynomial equa-tion describes the best distribution of statistical data. the dependence of hardened concrete density and compressive strength on type and percentage of chemical admixtures under different curing conditions can be described by polynomial dependencies. 4 density of concrete specimens with different type and amount of chemical admixtures cured by non-standard method correlation coefficients were in the range from 0.21 till 0.76 and density of concrete specimens cured by standard method – from 0.29 till 0.77. 5 compressive strength of concrete specimens with different type and amount of chemical admixtures cured by non-standard method correlation coefficients were in the range from 0.67 till 0.96 and compressive strength of concrete specimens cured by standard method – from 0.48 till 0.80. al-assadi g., casati m.j., fernandez j., galvez j.c. effect of the curing conditions of concrete on the behaviour under freeze–thaw cycles, fatigue & fracture of engineering materials & structures, 2010; 34: 461-470. http://dx.doi.org/10.1111/j.14602695.2010.01520.x albayraka g., canbaza m., albayraka u. statistical analysis of chemical admixtures usage for concrete: a survey of eskisehir city, turkey, procedia engineering, 2015; 118: 1236-1241. http://dx.doi. org/10.1016/j.proeng.2015.08.475 ali m.-a., murat t., gokhan y., omer a., kambiz r. effect of different types of superplasticizer on fresh, rheological and strength properties of self-consolidating concrete, construction and building materials, 2013; 47: 1020-1025. http://dx.doi. org/10.1016/j.conbuildmat.2013.05.105 atis c.d. strength properties of high-volume fly ash roller compacted and workable concrete and influence of curing condition, cement and concrete research, 2005; 35: 1112-1121. http://dx.doi. org/10.1016/j.cemconres.2004.07.037 atis c.d., ozcan f., kılıc a., karahan o., bilim c., severcan m.h. influence of dryand wet curing conditions on compressive strength of silica fume concrete, building and environment, 2005; 40: 1678-1683. http://dx.doi.org/10.1016/j.buildenv.2004.12.005 gayarre f.l., cabo a.d., pérez c.l.-c., lópez m. a. s. the effect of curing conditions on the compressive strength of recycled aggregate concrete, construction and building materials, 2014; 53: 260-266. http://dx.doi.org/10.1016/j.conbuildmat.2013.11.112 khatib j.m., mangat p.s. influence of superplasticizer and curing on porosity and pore structure of cement paste. cement and concrete composites, 1999; 21: 431-437. http://dx.doi.org/10.1016/ s0958-9465(99)00031-1 łazniewska-piekarczykb b. the influence of admixtures type on the air-voids parameters of nonair-entrained and air-entrained high performance scc, construction and building materials, 2013; 41: 109-124. http://dx.doi.org/10.1016/j.conbuildmat.2012.11.086 lazniewska-piekarczyka b. the influence of chemical admixtures on cement hydration and mixture properties of very high performance self-compacting concrete, construction and building materials, 2013; 49: 643-662. http://dx.doi.org/10.1016/j.conbuildmat.2013.07.072 ling i.h., teo d.c.l. properties of eps rha lightweight concrete bricks under different curing conditions, construction and building materials, 2011; 25: 3648-3655. http://dx.doi.org/10.1016/j.conbuildmat.2011.03.061 43 journal of sustainable architecture and civil engineering 2016/1/14 ling t.-ch., poon ch.-s., kou sh.-c. influence of recycled glass content and curing conditions on the properties of self-compacting concrete after exposure to elevated temperatures, cement and concrete composites, 2012; 34: 265-272. http://dx.doi. org/10.1016/j.cemconcomp.2011.08.010 plank j., sakai e., miao c.w., yud c., hong j.x. chemical admixtures chemistry, applications and their impact on concrete microstructure and durability, cement and concrete research, 2015; 78: 81-99. http://dx.doi.org/10.1016/j.cemconres.2015.05.016 saric-coric m., khayat k.h., tagnit-hamou a. performance characteristics of cement grouts made with various combinations of high-range water reducer and cellulose-based viscosity modifier, cement and concrete research, 2003; 33: 1999-2008. http://dx.doi.org/10.1016/s0008-8846(03)00214-x tan k., gjorv o. e. performance of concrete under different curing conditions, cement and concrete research, 1996; 26: 355-361. http://dx.doi. org/10.1016/s0008-8846(96)85023-x turkmen i. influence of different curing conditions on the physical and mechanical properties of concretes with admixtures of silica fume and blast furnace slag, materials letters, 2003; 57: 4560-4569. http://dx.doi.org/10.1016/s0167-577x(03)00362-8 zhao h., sun w., wu x., gao b. effect of initial water-curing period and curing condition on the properties of self-compacting concrete, materials and design, 2012; 35: 194-200. http://dx.doi. org/10.1016/j.matdes.2011.09.053 gintas brazas position at the organization master at faculty of civil engineering and architecture, department of construction technologies main research area civil engineering address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: gintas@gmail. com mindaugas daukšys position at the organization dr. at faculty of civil engineering and architecture, department of construction technologies main research area civil engineering, construction technology address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: mindaugas. dauksys@ktu.lt albertas klovas position at the organization ph.d student at faculty of civil engineering and architecture, department of construction technologies main research area civil engineering, construction technology address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: albertas. klovas@ktu.lt jolanta šadauskienė position at the organization dr. at faculty of civil engineering and architecture, department of building energy systems main research area civil engineering address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300492 e-mail: jolanta. sadauskiene@ktu.lt about the authors journal of sustainable architecture and civil engineering 2016/4/17 24 *corresponding author: janis.sliseris@gmail.com non–linear buckling analysis of steel frames with local and global imperfections http://dx.doi.org/10.5755/j01.sace.17.4.16644 jānis šliseris*, līga gaile, leonīds pakrastiņš riga technical university, kalku street 1, lv-1002, riga, latvia received 2016/10/31 accepted after revision 2016/12/12 journal of sustainable architecture and civil engineering vol. 4 / no. 17 / 2016 pp. 24-32 doi 10.5755/j01.sace.17.4.16644 © kaunas university of technology non-linear buckling analysis of steel frames with local and global imperfections jsace 4/17 the problem related to nonlinear analysis of steel frames is analyzed by taking into account local and global imperfections. a new method for estimation of optimal (in the worst case scenario causes smallest buckling load) pattern for geometrical and material imperfections is developed. the method is based on the optimization of structural topology. the topology is optimized in a way where maximal compliance (minimal stiffness) and strain energy is reached. according to the gradient of compliance function the pattern of geometrical and material imperfections is iteratively obtained. global geometrical imperfections are applied by using buckling modes (eigenmodes) with a pre calculated weight coefficient according to the compliance function for each buckling mode. the proposed methods showed to be robust and practically applicable for designing complex steel structures. keywords: steel frames, buckling, imperfection’s pattern, structural optimization. steel structural members are not geometrically perfectly shaped due to manufacturing and building tolerances. three types of initial imperfections should be taken into account in advanced (second-order inelastic) analysis: (i) the member out-of-straightness (bow imperfection), (ii) the frame out-of-plumb (sway imperfection) and (iii) local material imperfections (shayan et. al. 2014, papp 2016) such as deviation in young’s modulus or residual stress. the pattern of initial imperfections is often chosen to be the worst case scenario to maximize their destabilizing effects and compliance under the applied loads in a global frame analysis. the modelling of geometric and material imperfections is more complicated for a frame (or any spatial 3d structure) than for a single column because not only the magnitude but also the pattern (shape and the direction) of the imperfection affects the overall response of the frame. papadopoulos et. al. (2013) proposed a method for accounting portal frame’s stochastic imperfections that are described with non-homogeneous gaussian random fields by using brute monte carlo simulations. a similar method is used to take into account the effect of initial geometrical imperfections on the buckling load of steel tubes under axial load and lateral pressure (vryzidis et.al. 2013). this method is computationally too intensive and requires many parameters to describe the gaussian field of each type of imperfection, therefore it may be too complex for a practical engineer. special attention is paid to the buckling analysis of cold formed steel structures. as shown in the work done by garifullin and nackenhorst (2015), cshaped cold formed steel structures experience very complicated buckling and post-buckling behavior due to initial geometrical imperfections. these introduction 25 journal of sustainable architecture and civil engineering 2016/4/17 imperfections arise from their manufacturing process, shipping, storage and construction process. the geometric imperfections of cold formed steel members can be represented by the member eigenmode shapes. along with the classical measure (the amplitude of imperfections) an energy measure defined by the square root of the elastic strain energy hypothetically required to distort the originally perfect structural element into the considered imperfect shape – can be used (sadovský et. al. 2012). a non-linear buckling analysis of 2-d cross-aisle storage rock frames may be done using shell finite elements providing an idea about optimal structure (thombare et.al. 2016). as shown in work done by zeinoddini and schafer (2012), the imperfection measurements for cold-formed steel members can be simulated using (i) superposition of eigenmodes, (ii) multi-dimensional spectral representation or (iii) a combination of the modal approach and spectral representation. welding process can cause a significant residual stress and imperfections in the geometry. as shown in the publication done by sadowski et.al. (2015), the spiral welded carbon steel tubes may have a very unique pattern of surface imperfections. prediction of flexural buckling of stainless steel i-section and box-section columns may be problematic with current design standards (yang et.al. 2016a, yang et.al. 2016b). some works are done to define the equivalent geometric imperfection for analysis of steel structures that are sensitive to flexural and/or torsional buckling due to compression or bending moment (agüero et.al. 2015a, agüero et.al. 2015b). it is shown that beam element analysis can be used to account for second order effects in locally and/or distortionally buckled frames (zhang et.al. 2016b). this method is validated with experimental investigations (zhang et.al. 2016a). meanwhile, additional bending moments may arise due to geometrical global and local imperfections (baláž and koleková 2012). there is still on-going research on the smaller structural scale (meso scale), where computational homogenization methods are coupled with analysis of geometrical imperfections (goncalves et. al. 2016). the effect of mode interaction between local buckling and global buckling about the strong axis in thin-walled i-section struts can be taken into account with a simple analytical model (liu and wadee 2016). although extensive research has been conducted on advanced analysis for steel structural systems (shayan et. al. 2014), a robust mathematical method of estimation of initial geometric and material imperfection’s pattern in advanced non-linear analysis has not been developed. for this propose a novel method of estimation of material and geometrical imperfection patterns that can cause the maximal compliance of the structure is proposed. the maximal compliance indicates that the structure has minimal stiffness and it can be maximally easy to deform with a specific load case. this will also provide the worst buckling scenario and minimal buckling load. the material imperfections may be a local deviation of young’s modulus and local cross section imperfection. in this paper proposed a method that will take into account the local imperfections by performing structural topology optimization in the sense of maximizing structural compliance. meanwhile, there is also proposed a method for accounting for the global geometric in-plane imperfections that is based on the euler buckling analysis and a special method that combines the worst buckling modes to get the final imperfection’s pattern. in this study, 2d steel frames are analyzed. however, this method can be easily extended to a 3d case. this method can be easily implemented into a commercial structural engineering software. typically, structural topology optimization is used to optimize structures for maximal stiffness (minimal compliance) (tsavdaridis et.al. 2015, sliseris and rocens 2013), but in this case done contrary by maximizing the structural compliance. this will indicate locations in the structure that should be made weaker by applying imperfections to achieve worst scenario and minimal stiffness (maximal compliance) of the structure. in this case, we use structural topology optimization that seeks for the optimal deviation of young’s modulus in different locations of the structure to estimation of local imperfection’s pattern journal of sustainable architecture and civil engineering 2016/4/17 26 reach minimal stiffness (maximal compliance). optimization is based on 2d linear euler-bernoulli beam finite element analysis. young’s modulus of e-th element is assumed to be a function of the imperfections density given by the linear interpolation scheme as: where: �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) –young’s modulus for material without local imperfections (210 gpa is used in this work). where: �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) –non-smoothed vector of imperfection’s density. where: �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – global stiffness matrix, �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – geometrical stiffness matrix, �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – eigenvalues corresponding to the critical loads , is buckling modes and n corresponds to number of degrees of freedom. where: �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – indicates the width of the filter (in this work the width was equal to length of 3 finite elements). where: �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – the displacement vector, �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – global stiffness of structure, f – global force vector, n – number of finite elements, �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – volume of e-th finite element, �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – reference volume of structure that cannot be exceeded, �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – minimal value for imperfection’s density, �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) – maximal value of imperfection’s density. (1) (3) (5) (4) (2) �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) the structural topology optimization problem is formulated to maximize the compliance and strain energy �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) the values of imperfection density can be indirectly estimated from design codes (e.g. eurocode 3) or standards. the gaussian filter g is used in the optimization to smooth the final values of imperfection density function by calculating convolution �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) the gaussian smoothing function is given in a standard form: in practice, the easiest way is to represent imperfections density with the variation of young’s modulus and\or shear modulus for beam-like structures. the procedures how to evaluate young modulus is described in appropriate standards deeding on type of structure. the variation field is obtained by using monte-carlo type simulations. in a more complicated structures, where shell and solid type of finite elements are used, than the imperfections are modelled as a single coefficient (for isotropic material) or coefficient matrix (for anisotropic material) that reduce the coefficients in stiffness matrix. �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) in this paper is presented a method that is based on the work shayan et.al. (2014). this method is extended in a more mathematical way. first of all, the linear static analysis is performed to calculate the axial forces in each member. in the next step, the linear-buckling eigenvalue problem is solved estimation of global geometrical imperfection’s pattern �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) 27 journal of sustainable architecture and civil engineering 2016/4/17 buckling modes are scaled using a defined maximal global geometrical imperfection parameter where: �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) can be estimated by design standards (e.g. eurocode 3) or experimental measurements (sadowski et.al. 2015). where: m – corresponds to the number of buckling modes that should be taken into account for the final imperfection’s pattern calculation. (6) (9) (7) (8) the next step is to calculate structural compliance for each scaled buckling mode . the structural geometry is changed to the scaled buckling mode and static analysis is performed �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) �� = ��(1 − �(�)), (1) � � � � � ���� �(�)��� � = �� (�)�(�)�(�) �� �� � �(�)�(�) = � ∑ ������ � ��� − 1 ≤ 0 0 � ���� ≤ �� ≤ ���� , (2) �(�) = � �∗(�)�(� − �)���� , (3) �(� − �) = ������ � �(���) � ��� , (4) �� �� = �� ���� � �� = ���� � � = 1� � � �, (5) ��∗ = �� ���� ���(��) . (6) �(��∗)�(��∗) = � . (7) �� = �(��∗)� �(��∗)�(��∗)� � = 1� � � �. (8) the final geometrical imperfection’s pattern is obtained by calculation of weight coefficients for each buckling mode corresponding to the structural compliance: φ = ∑ ��∗ �� ∑ ������ � ��� , (9) the proposed methods are implemented into 64-bit matlab r2015a programming environment. a typical 2-story frame with 2 spans (see fig. 1) is analysed to show the performance of the proposed methods. the columns are made of hea 260 structural steel isections with length of 5 m. beams are made of ipe 400 structural steel isections with span of 10 m. the modulus of elasticity (without imperfections) is 210 gpa. the boundary conditions and applied loads are shown in the fig. 1. the entire structure is meshed with beam finite elements with size 0.5 m. the beam finite element is based on classical euler-bernoulli beam theory. results fig. 1 scheme of the 2d typical frame journal of sustainable architecture and civil engineering 2016/4/17 28 first of all, we estimated the optimal topology of local imperfections (e.g. deviations of young’s modulus or local cross section imperfections). the proposed method was successfully used and showed a good convergence (see fig. 2). the convergence was reached in 250 iterations. in the fig. 3. the topology of imperfections is shown. the thickness of member indicates the sensitivity of overall structural compliance to local imperfection in the member. as we can see, the middle columns have very large influence on the global stiffness and compliance of the frame. the horizontal members may not have an in-plane buckling (out of plane, torsional and flexural buckling are not considered in present work). this work indicates that for a simple 2d frame structure it may be possible to find the pattern of local imperfections by “hand” calculations considering members with the highest axial force. however, for a spatial 3d frame structure this method may significantly improve the methodology to identify the worst scenario (pattern of local imperfections). in future work this method will (a) (b) (c) be extended to 3d cases and a large spatial steel structure will be analysed. the pattern of global geometrical imperfections that can cause a worst case scenario is estimated for the same frame that is shown in fig.1. the first three buckling modes are shown in fig. 4. the proposed method is used to estimate the influence of each buckling mode on structural compliance. the fig .5. indicates that actually the first buckling mode is not the one that can cause maximal compliance. the second and fifth buckling mode show the maximal compliance (minimal stiffness) of the frame. the proposed method was used to estimate the worst pattern of global geometrical imperfections by considering (i) first 10 buckling modes (see fig. 6), (ii) first 50 buckling modes ( see fig. 7) and (iii) first 100 buckling modes). the simulations showed that higher buckling modes did not have a realistic shape (that can be observed in experimental investigations) and therefore were not taken fig. 2 structural compliance fig. 3 imperfection’s topology for material young’s modulus (or local cross section imperfections) corresponding to maximal compliance of the frame. thickness of the line corresponds to value 29 journal of sustainable architecture and civil engineering 2016/4/17 into account, since experimental observations (shayan et. al. 2014) of buckling modes did not identify any of higher buckling mode, therefore those modes was not takin into account. the research is still in progress and in succeeding works the proposed method will be extended to estimate the weight coefficient for each buckling mode in a more robust mathematical method using a compliance-gradient based topology optimization approach. fig. 4 typical buckling modes of the frame. (a) first buckling mode, (b) second buckling mode, (c) third buckling mode fig. 5 structural compliance for each buckling mode (eigenmode) a b c journal of sustainable architecture and civil engineering 2016/4/17 30 fig. 6 final shape with geometrical imperfection’s pattern when first 10 buckling modes are considered fig. 7 final shape with geometrical imperfection’s pattern when first 50 buckling modes are considered fig. 8 final shape with geometrical imperfection’s pattern when first 100 buckling modes are considered 31 journal of sustainable architecture and civil engineering 2016/4/17 a novel method for estimation of patterns of local and global geometrical imperfections that can cause worst case scenarios is proposed. the local imperfection’s pattern is estimated by using the structural topology optimization approach and seeking for the pattern that can cause a minimal stiffness (maximal compliance) of the overall structure. the pattern of global geometrical imperfections that can cause a minimal stiffness of frame is estimated by a special superposition of buckling modes. for each buckling mode a weight coefficient is calculated that depends on the structural compliance for this buckling mode. both methods can be effectively used in advanced non-linear buckling analysis of frames. the current work is not finished and the methods will be updated. in the future, the presented methods should be extended and coupled with non-linear finite element simulations. the global imperfections should be calculated iteratively by assigning weight coefficients for each buckling mode based on the topology optimization approach. conclusions acknowledgment the research leading to these results has received funding from the latvia state research programme under grant agreement “innovative materials and smart technologies for environmental safety, imateh”. the research leading to these results has received the funding from riga technical university, faculty of building and civil engineering grant “dok.bif”. support for this work was provided by the riga technical university through the scientific research project competition for young researchers no. zp-2016/1. agüero a., pallarés l., pallarés f.j. equivalent geometric imperfection definition in steel structures sensitive to flexural and/or torsional buckling due to compression. engineering structures, 2015a, 96: 160–177.https://doi.org/10.1016/j.engstruct.2015.03.065 agüero a., pallarés l., pallarés f.j. equivalent geometric imperfection definition in steel structures sensitive to lateral torsional buckling due to bending moment. engineering structures, 2015b, 96: 41–55. https://doi.org/10.1016/j.engstruct.2015.03.066 baláž i., koleková y. bending moments due to elastic buckling mode applied as uniform global and local initial imperfection of frames. procedia engineering, 2012, 40: 32 – 37. https://doi.org/10.1016/j.proeng.2012.07.051 garifullin m., nackenhorst u. computational analysis of cold-formed steel columns with initial imperfections. procedia engineering, 2015, 117: 1073 – 1079. https://doi.org/10.1016/j.proeng.2015.08.239 goncalves b.r.,jelovica j., romanoff j. a homogenization method for geometric nonlinear analysis of sandwich structures with initial imperfections. international journal of solids and structures, 2016, 87: 194–205. https://doi.org/10.1016/j.ijsolstr.2016.02.009 liu e., wadee m. mode interaction in perfect and imperfect thin-walled i-section struts suscepreferences tible to global buckling about the strong axis. thin-walled structures, 2016, 106: 228–243. https://doi.org/10.1016/j.tws.2016.04.027 papadopoulos v., soimiris g., papadrakakis m. buckling analysis of i-section portal frames with stochastic imperfections. engineering structures, 2013, 47: 54–66. https://doi.org/10.1016/j.engstruct.2012.09.009 papp f. buckling assessment of steel members through overall imperfection method. engineering structures, 2016, 106: 124–136. https://doi.org/10.1016/j.engstruct.2015.10.021 sadovský z., kriváček j., ivančo v., ďuricová a. computational modelling of geometric imperfections and buckling strength of cold-formed steel. journal of constructional steel research, 2012, 78: 1–7. https://doi.org/10.1016/j.jcsr.2012.06.005 sadowski a., es s., reinke t., rotter j., gresnigt a.m., ummenhofer t. harmonic analysis of measured initial geometric imperfections in large spiral welded carbon steel tubes. engineering structures, 2015, 85: 234–248. https://doi.org/10.1016/j.engstruct.2014.12.033 shayan s., rasmussen k., zhang h. on the modelling of initial geometric imperfections of steel frames in advanced analysis. journal of constructional steel research, 2014, 98: 167–177. https://doi.org/10.1016/j.jcsr.2014.02.016 journal of sustainable architecture and civil engineering 2016/4/17 32 sliseris j., rocens k. optimal design of composite plates with discrete variable stiffness. composite structures, 2013, 98: 15-23. https://doi.org/10.1016/j.compstruct.2012.11.015 thombare c., sangle k., mohitkar v. nonlinear buckling analysis of 2-d cold-formed steel simple cross-aisle storage rack frames. journal of building engineering, 2016, 7: 12–22. https://doi.org/10.1016/j.jobe.2016.05.004 tsavdaridis k.d., kingman j.j., toropov v.v. application of structural topology optimisation to perforated steel beams. computers and structures, 2015, 158: 108–123. https://doi.org/10.1016/j.compstruc.2015.05.004 vryzidis i., stefanou g., papadopoulos v. stochastic stability analysis of steel tubes with random initial imperfections. finite elements in analysis and design, 2013, 77: 31–39. https://doi.org/10.1016/j.finel.2013.09.002 yang l., zhao m., chan t., shang f., xuc d. flexural buckling of welded austenitic and duplex stainless steel i-section columns. journal of conjānis šliseris dr.sc.ing., senior researcher riga technical university, department of structural mechanics main research area mechanics of composite materials, natural fiber composites, finite element modelling address 6a, ķīpsalas iela 6, kurzemes rajons, rīga, lv-1048 tel.: +371 26214882 e-mail: janis.sliseris@gmail.com structional steel research, 2016a, 122: 339–353. https://doi.org/10.1016/j.jcsr.2016.04.007 yang l., zhao m., xu d., shang f., yuan h., wang y., zhang y. flexural buckling behavior of welded stainless steel box-section columns. thin-walled structures, 2016b, 104: 185–197. https://doi.org/10.1016/j.tws.2016.03.014 zeinoddini v.m., schafer b.w. simulation of geometric imperfections in cold-formed steel members using spectral representation approach. thin-walled structures, 2012, 60: 105–117. https://doi.org/10.1016/j.tws.2012.07.001 zhang x., rasmussen k., zhang h. experimental investigation of locally and distortionally buckled portal frames. journal of constructional steel research, 2016a, 122: 571–583. https://doi.org/10.1016/j.jcsr.2016.04.017 zhang x., rasmussen k., zhang h. second-order effects in locally and/or distortionally buckled frames and design based on beam element analysis. journal of constructional steel research, 2016b, 122: 57–69. https://doi.org/10.1016/j.jcsr.2016.01.022 about the authors līga gaile dr.sc.ing., professor riga technical university, department of structural mechanics main research area structural dynamics, structural design, steel structures. address 6a, ķīpsalas iela 6, kurzemes rajons, rīga, lv-1048 tel.: +371 6708 9262 e-mail: liga.gaile_1@rtu.lv leonīds pakrastiņš dr.sc.ing., professor riga technical university, institute of structural engineering and reconstruction main research area design of reinforced concrete, numerical modelling, experimental testing address 6a, ķīpsalas iela 6, kurzemes rajons, rīga, lv-1048 tel.: +371 6708 9145 e-mail: leonids.pakrastins@rtu.lv journal of sustainable architecture and civil engineering 2017/4/21 50 the environmental performances of reclaimed asphalt and bituminous sand pavements for transition towards low carbon sustainable road infrastructure received 2017/10/09 accepted after revision 2017/12/18 journal of sustainable architecture and civil engineering vol. 4 / no. 21 / 2017 pp. 50-62 doi 10.5755/j01.sace.21.4.18486 © kaunas university of technology the environmental performances of reclaimed asphalt and bituminous sand pavements for transition towards low carbon sustainable road infrastructure jsace 4/21 mihaela condurat* regional directorate of roads and bridges iasi (d.r.d.p. iasi), romanian national company of road infrastructure management (c.n.a.i.r. s.a romania), gh. asachi street, iasi, 700481, romania gabriela ionita department of transportation infrastructure and foundations, faculty of civil engineering and building services, gheorghe asachi” technical university of iasi, 43, dimitrie mangeron blvd., iasi 700050, romania given the climate change, the high levels of pollution and the depletion of natural resources, the adoption of low carbon practises for road infrastructure improvement with regards to energy consumption is essential for a sustainable future. these practises, including the incorporation of nonconventional materials, such as oil sands or bituminous sands in pavement construction and the recycling of the existing deteriorated pavements, represent significant methods which can be performed for a better conservation of resources, and therefore the protection of the environment. in terms of environmental indicators assessment, the results of recent research undertaken for road pavement reinforcement strategies are presented. the global warming potential expressed as quantities of co2e emissions for a road pavement incorporating various alternative materials, such as oil sand and reclaimed asphalt has been evaluated using a life cycle assessment (lca) study performed with aspect software. the results obtained from these studies are presented within this paper and specific recommendations with regards to various employed approaches are given. these are required for minimizing the environmental impact of transport infrastructure. the paper aims to highlight the need for effective measures concerning road pavements maintenance and intervention works. these measures are intended to extend the pavements lifecycle and therefore to reduce the overall ecological impact associated with the reconstruction of the road pavement because this action is correlated with significant quantities of polluting emissions released into the atmosphere, enormous granular materials and energy consumption and thus, an exponential increase of the greenhouse effect. keywords: bituminous sand, environmental impact, life-cycle assessment, reclaimed asphalt pavement, road pavement. *corresponding author: conduratmihaela@yahoo.com http://dx.doi.org/10.5755/j01.sace.21.4.18486 51 journal of sustainable architecture and civil engineering 2017/4/21 introduction general concepts of low carbon practices associated with road pavements defining low carbon mobility can be achieved by taking into account specific actions related to the transport system which leads to significantly reduced consumption of non-renewable resources and smaller quantities of greenhouse gas emissions released into the atmosphere (condurat and patterson, 2016). in terms of new technologies and processes supporting the transition towards low carbon mobility, as a consequence of the alarming increase in pollution levels worldwide during the last years, the need to promote alternative road construction methods has emerged. the progressive increase in the demand for asphalt mixtures and therefore for road bitumen, correlated with material quantitative and qualitative deficiencies have emphasized the importance of nonconventional components in the asphalt mixes, such as bituminous sand and reclaimed asphalt pavements. thus, the paper will emphasize the new developments related to transport infrastructure towards low carbon mobility represented in our case by the incorporation in pavement construction of nonconventional materials, such as oil sands or bituminous sands and recycling techniques of the existing deteriorated pavements within the process of rehabilitation of the road network. given that the rehabilitation possibilities are limited due to high costs and the fact that the bituminous binder at this stage is imported, oil sand is an effective alternative. bituminous sand is a local material, specific only to certain areas of the world, which have the advantage of containing in their natural state, a percentage of natural bitumen. using oil sands is imposed by the continuously increasing price for bituminous binders, along with the gradual degradation of romanian road network, in connection with the increase of fleet vehicle composition. low carbon road infrastructure improvement practises, including incorporation of waste and recycling materials in pavement construction and recycling techniques of the existing deteriorated pavements represent significant methods which can be performed for a better conservation of resources, while being environmental friendly. the long term positive results, correlated with the recycling process, include the reduction of the natural resources depletion and thus a reduction of environmental impacts of the road pavement, decrease of materials consumption, energy usage, construction waste and associated costs (al-qadi, sayed, alnuaimi, and masad, 2008; al-rousan, asi, al-hattamleh, and al-qabla, 2008). the use of oil sands in the road pavement construction sector incorporating alternative materials in road pavements comes with great benefit to the society. in order to minimize the dependency on the petroleum-based asphalt, bituminous sand can be easily used. the aim of this paper is to emphasize the ecological benefits related with an asphalt pavement mix designed with a percentage of oil sand incorporated into the mix, which has previously been tested in a road laboratory and it has proven to fulfil the physical and mechanical characteristics of road pavements (ioniţă and gugiuman, 2016). bituminous binders are complex mixtures of animal origin hydrocarbons or are obtained through a pyrogenic reaction, often together with their combinations with oxygen, nitrogen, sulphur, etc. bituminous sands are found in liquid, viscous or solid form, having a dark brownish and black colour and are completely soluble in carbon disulfide (matasaru, craus, and dorobantu, 1966; ioniţă and gugiuman, 2016). oil sands are sand deposits impregnated with a thick, viscous material called bitumen (speight, 2009). these are mixtures composed of quartz sand and fine particles, thin water cover and bitumen that fill the pore spaces between the sand granules (probstein and hicks, 2006). major bituminous sand deposits are found around the world; yet, the largest deposits are located in north america and eurasia. the largest bituminous sand field is found near athabasca, alberta canada, but there are significant oil reserves located in venezuela (lake bermudes), syria, cuba, madagascar, albania (selene) (anochie-boateng and tutumluer, 2012). journal of sustainable architecture and civil engineering 2017/4/21 52 in the “economic feasibility of oil sand use in asphalt pavements”, a comparative economic analysis of these two alternatives is performed and the conclusion drawn was “an overall favorable economic result for private industry, as well as, both local and state governments is predicted” (gwilliam, 2010). another benefit of bituminous sand road pavements is the reduced mixing temperature. the mixing temperature for classical hot asphalt mix is about 177° c compared to 104°c which is the optimum mixing temperature for bituminous sand mixes (vrtis, 2013). as it can be seen, there is a substantial reduction in the mixing temperature for the second alternative, which can be translated into a more environmentally friendly pavement by reducing the emissions produced by these processes latter. in romania, oil sands are located in two geographical zones, as follows: bihor county, at derna tatarus budoi site and prahova county, at matita and pacuret site. these bituminous sands have an average of 10 to 20% pure bitumen in their structure and therefore can be used for road works. depending on the road works for which these bituminous sands are used, the bituminous mixtures can be designed only with bituminous sand or bituminous sand and additional hard paving grade bitumen (ionita and gugiuman, 2016). the technological process of extraction is surface mining due to the fact that the oil sand deposits are at a shallow depth below the thin layer of soil. reclaimed asphalt pavement when distresses appear in the road pavement affecting the structural integrity of the road and the operational status of the surface, in order to meet the criteria for reducing ghg emissions and using smaller amounts of materials, pavement recycling is an essential process. the technological process of recycling asphalt mixtures consists in the usage of material derived by milling, grinding and mixing these with correspondent amounts of binder and natural aggregates. the material obtained is then properly bedded and compacted. the asphalt course obtained using this procedure must meet the quality requirements of new asphalt mixtures, namely workability, compaction, mechanical stability and insensitivity to water (florescu, 2010). the dosages of materials incorporated in recycled mixtures are established through laboratory studies for asphalt pavements design, the dosage of embedded reclaimed asphalt pavement (rap) varying between 20% (europe) and 70% (usa) (fhwa, 2011). transport research laboratory (trl) has been conducted studies upon recycled materials in order to determine the viability and the behaviour of mixtures that have different quantities of asphalt waste (up to 30%) and polymer modified bitumen. thus, an amount of 10% recycled asphalt (ra) material can be incorporated into the mixes without previously processing the reclaimed material. the proportion of ra can increase up to 50%, if the homogeneity of the ra is controlled. in this case, the effect of residual binder in the ra on the active binder is also to be taken into consideration (al-qadi, sayed, alnuaimi, and masad, 2008). in romania, the recycling of flexible asphalt pavements is not current practice, despite the need, the economic, environmental and social benefits and the physical and mechanical characteristics similar to those of new materials. usually, the rap is stored in landfills, used for the execution of the binder course for low road category or as filler material. thus, the impact associated with the use of rap, expressed in terms of pollutant emissions, has been further analysed in this paper, not only taking into consideration the actual practice (as additional material in the binder course), but also within all bituminous layers. the life cycle assessment analysis life cycle assessment (lca) enables the definition of the potential environmental impact assessment associated with the product throughout its lifetime (using non-renewable resources, health, ecological consequences, etc.) in order to increase resource efficiency and to remove its quality issues (treweek, 2009). the lca is realized according with international standards iso 14040 and iso 14044. the lca method enables the identification of opportunities for improving the environmethods 53 journal of sustainable architecture and civil engineering 2017/4/21 mental aspects at various times in their life cycle and the selection of performance indicators and measurement techniques, and is considered a practical instrument in the decision making processes. a life cycle assessment analysis of a system product is performed stepwise as shown in fig. 1. based on a lca analysis, series of indicators can be quantified, the most representative being the global warming potential (gwp). this indicator represents the contribution of carbon dioxide (co2), methane (ch4), nitrous oxide (n2o), hydrofluorocarbons (hfcs), perfluorocarbons (pfcs) and sulphur hexafluoride (sf6) to the exacerbation of global warming. though, the carbon dioxide has the highest contribution to the global warming effect. taking into consideration the importance of this indicator, specific analyses for the evaluations of the ecological effect of a road pavement reinforcement will be further presented, expressed in terms of co2e emissions. the options for defining the boundaries are represented by cradle to grave, cradle to gate, gate to grave and gate to gate (curran, 2012). fig. 1 steps in performing a life cycle assessment (iso, 1997) 1. goal and scope definition 3. impact assessment 4. interpretation 2. inventory analysis furthermore, the paper will present the influence of various reinforcement strategies for asphalt road pavements through a life cycle assessment analysis conducted according to the methodology incorporated into the aspect software, version 3.1., in a „cradle-to-grave” perspective in order to only determine the global warming potential correlated with these strategies. aspect software methodology the aspect software, version 3.1 has been developed by trl and provides a new methodology to determine the pollutant emissions released into the atmosphere during the pavement life cycle due to asphalt materials used on road constructions. this software allows the assessment of carbon dioxide emissions on the basis of collected information regarding materials, transport and mixture plant characteristics (trl, 2014). the software enables calculation of co2e emissions related with the production, laying and maintenance of road layers by considering all the stages of materials and energy production and all the processes from raw material extraction, production, transport and use phase of the asphalt mixes to the end of their life (cradle to grave), shown in fig. 2. co2e or carbon dioxide equivalent is an abbreviation which expresses the effect of each various greenhouse gas regarding the amount of co2 that would produce the same amount of global warming (epa, 2009). fig. 2 the life cycle stages of asphalt mixtures cradle to grave (trl, 2014) journal of sustainable architecture and civil engineering 2017/4/21 54 according specialized literature (trl, 2014), the process for calculating the co2e emissions associated to bituminous road pavement consists of three main stages, namely: a. the introduction of raw materials used in the asphalt mixture (total annual energy consumption for the acquisition, broken down by type of fuel and operation); b. data introduction regarding the asphalt mixes plant characteristics (plant type, annual production, energy consumption and asphalt mix composition); c. data introduction regarding installation of bituminous mix and visualization of the results. in order to improve road infrastructure and to promote and stimulate alternative materials and technologies usage in road construction, in the past years, various studies regarding the incorporation of bituminous sand from several romanian sites into asphalt mixes, as well as reclaimed asphalt materials have been initiated and tested in the frame of “gheorghe asachi” technical university of iasi at an extensive scale. the studies required as a response to the actual environmental and energetic challenges, involves the reinforcement of a road pavement for light traffic using different engineering approaches. road pavements for light traffic are usually carried out from coated materials and bitumen macadam, applied in a singular layer over the existing gravelling. the service life of road pavements for light traffic is about 8 to 12 years. the disadvantages associated with bituminous sand pavements are the following: _ the high bitumen variation in the content of bituminous sands, _ the technical qualities of the sand, _ the impossibility of a perfect control of the technological process, this type of a material cannot be used for roads with intense and heavy traffic. however, oil sands present positive technical behaviour when used for reinforcing the asphalt road pavements for light traffic. reinforcement works are being performed in order to total or partial compensate the physical wear due to normal operation or environmental agents actions, upgrading the technical characteristics imposed by an increased road traffic, replacement of elements, parts of construction that are out of use, all of which affect the resistance, stability, safety in operation and environmental protection. the reinforcement works are usually carried out through two asphalt courses, laid on the existing road pavement. methods for the case study considering the elevated levels of pollution recorded during the last years and the european commission studies, the development of alternative road construction technologies and processes is required. moreover, besides the initial construction process of the road pavement, the periodical maintenance and reinforcement strategies to be applied represent significant factors for reducing the carbon footprint and, also, in increasing the service life time of the road. further, a more significant key role in decreasing polluting emissions is represented by the time of intervention. if the reinforcement strategy is applied at the optimum moment in the road service life, the costs and the raw materials and energy consumption will be considerably reduced and the lifetime of the road will be enlarged. otherwise, if the road is not reinforced when needed, the distresses progress exponentially, leading to the inability to use the road on full safety and comfort conditions. additionally, the rehabilitation investments, seen both in a financial perspective, as well as in terms of material consumption and labour required, will be directly correlated with the worsening of greenhouse effect. the paper shows the final results of recent research undertaken associated with the quantitative assessment of carbon dioxide equivalent emissions and energy consumption correlated with various reinforcement strategies for road pavements for light traffic using the aspect software. case study – life cycle assessment of reinforced road pavements using various alternative materials 55 journal of sustainable architecture and civil engineering 2017/4/21 the research based on environmental criteria of transport infrastructure has been performed using a life cycle assessment analysis (lcaa). the case study deals specifically with road pavement reinforcement strategies taking into consideration various nonconventional materials. the life cycle assessment analysis has been conducted on the entire built section of 1000 ml long and 7.0 m wide using a cradle to grave option, presented in fig. 2. the global warming potential, expressed in terms of co2e emissions has been assessed using the aspect software, version 3.1. the case study was conducted taking into consideration six constructive alternatives, presented in fig. 3, for the reinforced road infrastructures for light traffic, as follows: according alternative 1, the reinforced road pavement is composed of the asphalt concrete with the maximum size of the aggregate of 16 mm (ba 16) for the wearing course, laid on an asphalt concrete with the maximum size of the aggregate of 25 mm (bad 25) for the binder course, supported by the asphalt base (ab2), constructed over the existing structure. fig. 3 alternatives for the reinforced road pavements according alternative 2, the reinforced road pavement is composed of the recycled asphalt concrete with the maximum size of the aggregate of 16 mm (bar 16) for the surface layer, laid on a recycled asphalt concrete with the maximum size of the aggregate of 25 mm (badr 25) for the binder course, supported by a recycled asphalt base (abr). alternative 3 refers to a reinforced road pavement composed of an asphalt concrete course, laid on an asphalt concrete binder course, supported by a recycled asphalt base. this is the common practice in romania at this stage, but there are studies undergoing for the implementation of recycling materials in all the road pavement layers. for the alternative 4, the reinforced road pavement is composed of the asphalt concrete with bituminous sand incorporated into the mix (ba 16 n.b.) for the wearing course, laid on an asphalt concrete with bituminous sand (ba 1 25 n.b.) for the binder course, supported by the asphalt base also designed with bituminous sand (ab n.b.). for the alternative 5, the reinforced road pavement is composed of the recycled asphalt concrete having bituminous sand incorporated into the mix (bar 16 n.b.) for the surface layer, laid on a recycled asphalt concrete with bituminous sand (bar 1 25 n.b.) for the binder course, supported by a recycled asphalt base with bituminous sand (abr n.b.). journal of sustainable architecture and civil engineering 2017/4/21 56 for the alternative 6, refers to a reinforced road pavement composed of an asphalt concrete course with bituminous sand, laid on an asphalt concrete binder course with bituminous sand, supported by a recycled asphalt base also with bituminous sand into their composition. table 1 co2e emissions correlated with alternative 1 for road pavement reinforcement alternative 1: project results summary for alternative 1 are presented below, in table 1.results and discussions alternative 1 considers a classical road pavement, as a reinforcement solution. the road pavement is composed by three asphalt courses with different technical characteristics. from an ecological perspective, this solution is highly polluting. the energy and raw material consumption are the greatest from all the others studied alternatives. the main reason is derived from the fact that this construction option requires only virgin aggregates and the amount of bitumen used is between normal values (4.5 % 6.5%), while in the other alternatives this percentage is reduced. the total quantity of co2e associated with the classical road reinforcement alternative, in a cradle to grave perspective is 1.316.953,33 kg. thus, in order to move towards low carbon road infrastructure, more eco efficient strategies have been further assessed. alternative 2: project results summary for alternative 2 are presented in table 2. in order to comply with the low carbon road infrastructure principles, the recycling road pavement process has become more and more important. hence, a reinforcement road pavement alternative, carried out with reclaimed asphalt pavement incorporated into the mix has been designed and analyzed in terms of ecological impact during their life cycle. as it can be observed from the table 2, the results obtained for this alternative are significantly smaller compared with the classical road pavement, with only a 271,25 kg co2/t from a cradle to grave perspective. this study emphasizes the need to adopt greener ways to construct the transport infrastructure by reusing the existing material laid previously in combination with smaller quantities of virgin aggregates. also, the fact that the reclaimed asphalt pavement already has an amount of bitumen in their composition; a reduced quantity of the bituminous binder can be used, which translates into a reduction of the carbon footprint associated with this strategy. step life cycle stage kg co2/t total kg co2e 1-3 material extraction and processing 52,88 203.405,60 4 transport to plant 36,52 140.481,67 5 asphalt production 199,99 769.258,85 6 transport to site 30,17 116.052,11 7 laying and compacting 4,70 18.078,55 8 project works 0,00 0,00 9 maintenance 34,27 5.140,00 10 end of life 16,78 64.536,55 steps 1 to 7 asphalt project total kg. co2e 1.247.276,78 1.316.953,33 1.316.953,33 tonnes 3996,50 3996,50 kg co2e/tonne 324,26 329,53 57 journal of sustainable architecture and civil engineering 2017/4/21 table 2 co2e emissions correlated with alternative 2 for road pavement reinforcement step life cycle stage kg co2/t total kg co2e 1-3 material extraction and processing 20,89 80.371,19 4 transport to plant 22,03 84.752,61 5 asphalt production 185,91 715.119,14 6 transport to site 30,17 116.052,11 7 laying and compacting 4,70 18.078,55 8 project works 0,00 0,00 9 maintenance 34,27 5.140,00 10 end of life 16,78 64.536,55 alternative 3 project results summary for alternative 3 are presented below, in table 3. steps 1 to 7 asphalt project total kg. co2e 1.014.373,61 1.084.050,16 1.084.050,16 tonnes 3996,50 kg co2e/tonne 263,71 271,25 table 3 co2e emissions correlated with alternative 3 for road pavement reinforcement step life cycle stage kg co2/t total kg co2e 1-3 material extraction and processing 23,71 91.206,62 4 transport to plant 25,86 99.478,14 5 asphalt production 191,73 737.484,41 6 transport to site 30,17 116.052,11 7 laying and compacting 4,70 18.078,55 8 project works 0,00 0,00 9 maintenance 34,27 5.140,00 10 end of life 16,78 64.536,55 in this alternative, it has been considered only the base course carried out with reclaimed asphalt pavement. this is the usual procedure in romania despite the good behaviour and the physical and mechanical characteristics of the rap materials. although this alternative shows positive outcome in terms of environmental impact, in order to move towards low carbon road infrastructure, further steps have to be taken, namely entire road asphalt pavement recycling and incorporating other unconventional materials. steps 1 to 7 asphalt project total kg. co2e 1.062.299,83 1.131.976,38 1.131.976,38 tonnes 3996,50 kg co2e/tonne 276,17 283,24 journal of sustainable architecture and civil engineering 2017/4/21 58 alternative 4 project results summary for alternative 4 are presented below, in table 4. table 4 co2e emissions correlated with alternative 4 for road pavement reinforcement step life cycle stage kg co2/t total kg co2e 1-3 material extraction and processing 5,30 20.484,06 4 transport to plant 23,29 90.075,92 5 asphalt production 173,49 670.848,68 6 transport to site 30,17 116.664,58 7 laying and compacting 4,70 18.173,96 8 project works 0,00 0,00 9 maintenance 34,27 5.140,00 10 end of life 16,78 64.875,56 alternative 4 presents a reinforced road pavement carried out by incorporating an amount of bituminous sand extracted from derna tatarusi site, which contains 20% natural bitumen in their composition. hence, the amount of bituminous binder in the asphalt mix decreases significantly. this reduction is directly correlated with the quantity of carbon dioxide emissions released into the air. also, the fact that the oil sand does not need complicated excavation methods and technologies, given the close proximity to the top soil, emphasize the eco-efficiency of this alternative. alternative 5 project results summary for alternative 5 are presented below, in table 5. steps 1 to 7 asphalt project total kg. co2e 916.247,20 986.262,76 986.262,76 tonnes 4016,80 kg co2e/tonne 236,95 245,53 table 5 co2e emissions correlated with alternative 5 for road pavement reinforcement step life cycle stage kg co2/t total kg co2e 1-3 material extraction and processing 4,59 17.766,64 4 transport to plant 14,30 55.286,78 5 asphalt production 175,91 680.190,67 6 transport to site 30,17 116.664,58 7 laying and compacting 4,70 18.173,96 8 project works 0,00 0,00 9 maintenance 34,27 5.140,00 10 end of life 16,78 64.875,56 steps 1 to 7 asphalt project total kg. co2e 888.082,63 958.098,19 958.098,19 tonnes 4016,80 kg co2e/tonne 229,67 238,52 59 journal of sustainable architecture and civil engineering 2017/4/21 based on the results obtained from the alternatives studied above, one can notice the ecological advantage of incorporating into the mix of reclaimed asphalt pavement material or bituminous sand. however, as table 4 shows, blending these two procedures, have the most positive ecological outcomes. the total quantity of co2e from cradle to gate is 958.098,19 kg, almost with 27.25% smaller than the classical reinforcement solution. the ecological benefits derived from these results are significant, given the scale of road constructions. fig. 4 presents the emissions segmentations based on the life cycle stage. as it can be seen below, the biggest proportion of fig. 4 global warming potential expressed in terms of kg co2e/t associated with the most eco efficient reinforcement strategy pollutant emissions comes from the asphalt production. a big part in the emissions reduction is played by the temperatures required for the asphalt mixes with oil sand and rap, significantly lower compared with a typical solution. also, the emissions associated with the transport to the plant and material extractions and processing phases are smaller, as a direct consequence of the unconventional materials added. alternative 6 project results summary for alternative 6 are presented below, in table 6. table 6 co2e emissions correlated with alternative 6 for road pavement reinforcement step life cycle stage kg co2/t total kg co2e 1-3 material extraction and processing 4,69 18.124,32 4 transport to plant 16,66 64.410,40 5 asphalt production 174,96 676.546,22 6 transport to site 30,17 116.664,58 7 laying and compacting 4,70 18.173,96 8 project works 0,00 0,00 9 maintenance 34,27 5.140,00 10 end of life 16,78 64.875,56 steps 1 to 7 asphalt project total kg. co2e 893.919,47 963.935,03 963.935,03 tonnes 4016,80 kg co2e/tonne 231,18 239,98 journal of sustainable architecture and civil engineering 2017/4/21 60 alternative 6, with bituminous sand, compared with the first three studied alternatives also presents positive effects on the environment, even if the reclaimed material is only added in the base course. as it can be observed the total quantity of co2e/tonne released into the atmosphere due to the execution of a reinforced road pavement using recycled asphalt base and bituminous sand within the bituminous mixes is equal with 239,98 kg. this is translated as well with ecological advantages compared with the classical ones. the global warming potential, expressed in terms of co2e emissions has been assessed using the aspect software, developed by trl laboratory form uk. the results, broken down accordingly with the life cycle stages for the six alternatives considered are presented in table 7. table 7 summary of co2e emissions associated with the alternatives for the reinforced road pavements no. life cycle stage alternative 1 alternative 2 alternative 3 alternative 4 alternative 5 alternative 6 kg co2e/t kg co2e/t kg co2e/t kg co2e/t kg co2e/t kg co2e/t total kg co2e from cradle to site co2e/t 1.247.276,78 324,26 1.014.373,61 263,71 1.062.299,8 276,17 916.247,20 236,95 888.082,63 229,67 893.919,47 231,18 as it can be noticed from the chart above (fig. 5), the greatest proportion of co2e corresponds to the production of asphalt mixture due to the high energy consumption required for heating and drying the aggregates, mixing the components and other additional process from the plant. however, from the plant point of view, these emissions quantities can significantly decrease if one uses bituminous sand in the asphalt mix, mostly due to the low temperatures required into the technological process and the fact that these asphalt mixtures are carried out with smaller quantities of bitumen, material which, according recent studies (trl, 2014) has about 190,00 kg co2e/t. furthermore, the pollutant emissions associated with the material extraction and processing life cycle stage is reduced in the case of the oil sand, because this material is found at a shallow depth below the soil in romania. thus the technological processes are minimal. also, the extraction procedure is represented by surface mining or open pit. as expected, the most eco efficient reinforcement strategy for road pavement designed for light traffic is represented by alternative 5, which combines the use of both unconventional materials in the asphalt courses, the total co2e reaching fig. 5 co2e emissions associated with the alternatives for the reinforced road pavements expressed in terms of kg co2e /t for each of the life cycle stage of the reinforced road pavement 61 journal of sustainable architecture and civil engineering 2017/4/21 888.082,63 kg in a cradle to site perspective. this means that, compared with the most polluting alternative (a1 – classical reinforcement solution), the pollution decreases with almost 30%. in the same context the costs will also decrease as local and recycled materials are incorporated into the asphalt mixes. in conclusion, reinforcing the existing structure with unconventional materials shows positive impacts expressed in terms of environmental and economic effects through the use of small amounts of raw materials and energy required for extraction. furthermore, to decrease the ecological impact of road transport infrastructure, a significant factor is represented by the humidity of component materials, as the biggest amount of energy is consumed in drying and heating of aggregates. also, another way to increase the efficiency of asphalt production processes implies the use of reclaimed asphalt mixtures and oil sand, when the material is available near the road sites, which results in considerable reductions of pollutant emissions. the aim of this paper is to emphasize the ecological benefits related with an asphalt pavement mix designed with a percentage of oil sand incorporated into the mix, which has previously been tested in a road laboratory and it has proven to fulfil the physical and mechanical characteristics of road pavements. thus, considering that the most serious environmental issues facing mankind nowadays is represented by the global warming and climate change mostly due to high concentration of pollutants emitted into the air, the paper presents the results of recent research studies undertaken for the assessment of environmental indicators associated to road pavements reinforcement, based on a cradle to grave perspective, which involves all of the stages from raw material extraction, production, transportation and use phase of the products to their end of life. the environmental analyzes have been conducted on the entire built section of one-kilometre-long and 7,0 m wide using a cradle to grave option, contained in the aspect software. the life cycle assessment analysis has been conducted on six reinforcement road alternatives for light traffic using various unconventional materials, namely oil sand or bituminous sand supplied from derna tatarusi site and reclaimed asphalt pavement, derived from milling and grinding the asphalt road surface. one may notice that in order for bituminous sand road pavements to be used instead of conventional asphalt ones, these have to be advantageous in terms of costs, while still fulfilling the physical and mechanical characteristics. the economic and ecological advantages of bituminous sand road pavements decline as further the material has to be transported away from the site, due to transportation distance. given that the sand is already mixed with the bituminous binder, in the case of oil sands, transportation costs decrease compared with the traditional asphalt mixes, where transporting the binder leads to additional costs. as expected, the most eco efficient reinforcement strategy for road pavement designed for light traffic is represented by alternative 5, which combines the use of both unconventional materials in the asphalt courses, the total co2e reaching 888.082,63 kg in a cradle to site perspective. this means that, compared with the most polluting alternative (a1 – classical reinforcement solution), the pollution decreases with almost 30%. in the same context the costs will also decrease as local and recycled materials are incorporated into the asphalt mixes. in conclusion, reinforcing the existing structure with unconventional materials shows positive impacts expressed in terms of environmental and economic effects through the use of small amounts of raw materials and energy required for extraction. however, a close attention should be given for the asphalt mixtures temperatures and the technological process in order for these pavements to efficiently perform under traffic. the main disadvantage associated with the use of these unconventional materials is the fact that, for now, it cannot be used for roads with high traffic due to the major safety risks and quality requirements correlated with the pavements usually used on that types of roads. in this context further studies are required to be performed in order to continuously improve the pavements which have unconventional materials incorporated into the mixes from the physical and mechanical point of view. conclusions journal of sustainable architecture and civil engineering 2017/4/21 62 al-qadi, i. l., sayed, t., alnuaimi, n., and masad, e. efficient transportation and pavement systems: characterization, mechanisms, simulation, and modeling. crc press, 2008. al-rousan, t., asi, i., al-hattamleh, o., and al-qabla, h. performance of asphalt mixes containing rap. jordan journal of civil engineering, 2 (3), (pp. 218-227), 2008. anochie-boateng, j. k., and tutumluer, e. sustainable use of oil sands for geotechnical construction and road building. journal of astm international, (p. 33), 2012. condurat, m., and patterson, j. welsh and romanian policies for transition towards low carbon mobility. proceedings of the international conference “smart energy regions”, (pp. 59-70). cardiff, u.k, 2016. curran, m. a. life cycle assessment handbook: a guide for environmentally sustainable products. john wiley & sons, 2012. https://doi. org/10.1002/9781118528372 epa, opportunities to reduce greenhouse gas emissions through materials and land management practices u.s. environmental protection agency, 2009. office of solid waste and emergency response fhwa. asphalt pavement recycling with reclaimed asphalt pavement (rap). on line at: http://www. fhwa.dot.gov/pavement/recycling/rap/index.cfm. federal highway administration. us department of transportation, 2011. florescu, e. tehnologii speciale pentru reabilitarea drumurilor [special technologies for roads rehabilreferences itation]. ed. matei-teiu botez academic society iaşi, isbn 978-973-8955-91-2, 2010. gwilliam, t. s. economic feasibility of oil sand use in asphalt pavements. utah science technology and research initiative (ustar), 2010. ioniţă, g., and gugiuman, g. the usage of bituminous sands in road pavement asphalt mixtures composition. in international scientific journal trans & motauto world, year i, issue 2/2016, issn 2367-8399, scientific technical union of mechanical engineering, (pp. 40 – 42), 2016. iso. 14040, life cycle assessment principles and framework, 1997 matasaru, t., craus, i., and dorobantu, s. drumuri [roads]. bucuresti: editura tehnica bucuresti, 1966. probstein, r. f., and hicks, e. e. synthetic fuels, oil shale and tar sands. (pp. 183-184). new york, dover publication inc, 2006. speight, j. g. (2009). coal, oil shale, natural bitumen, heavy oil and peat volume 2 coal, oil shale, natural bitumen, heavy oil and peat volume 2. (p. 452). isbn: 978-1-84826-018-4 (ebook) isbn: 9781-84826-468-7, 2009. treweek, j. ecological impact assessment. wiley-blackwell, 2009. trl. asphalt pavement embodied carbon tool. transport research laboratory. online at http:// www.sustainabilityofhighways.org.uk, 2014. vrtis, m. c. creating a performance-based asphalt mix design to incorporate uinta basin oil sands. master thesis. department of civil and environmental engineering, the university of utah, 2013. condurat mihaela phd, eng (civil engineering) regional directorate of roads and bridges iasi (d.r.d.p. iasi), romanian national company of road infrastructure management (c.n.a.i.r. s.a romania) main research area impact assessment of road transport system. measures regarding the prevention and reduction of ecological impact associated with road transport infrastructure address gh. asachi street, no 19, postal code 700481, iasi, romania tel. +40 745 409 930 e-mail: conduratmihaela@yahoo.com gabriela ionita phd student, (civil engineering) department of transportation infrastructure and foundations, faculty of civil engineering and building services, gheorghe asachi” technical university of iasi main research area bituminous sand usage in the road technology in romania address dimitrie mangeron blvd., no 43, iasi 700050, romania e-mail: gabrielaa.ionitaa@yahoo.com about the authors 51 journal of sustainable architecture and civil engineering 2016/1/14 *corresponding author: tadas.zingaila@ktu.edu influence of heat treatment regimes on mechanical properties of nsc-uhpc composite members received 2016/05/28 accepted after revision 2016/07/05 journal of sustainable architecture and civil engineering vol. 1 / no. 14 / 2016 pp. 51-59 doi 10.5755/j01.sace.14.1.15820 © kaunas university of technology influence of heat treatment regimes on mechanical properties of nscuhpc composite members jsace 1/14 http://dx.doi.org/10.5755/j01.sace.14.1.15820 introduction tadas zingaila*, mindaugas augonis, evaldas šerelis, šarūnas kelpša, deividas martinavičius kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania the applicability of ultra-high performance concrete which has clearly better mechanical properties than ordinary concrete is one of the most common topics in civil engineering scientific papers. due to the high price of this type of concrete in comparison with ordinary concrete, and the absence of design codes, practical application of this type of material is still very limited, especially in less developed countries. the idea of partial usage of uhpc in some kind of structures is being developed by other scientists (habel 2004), however it is still the lack of information about curing conditions of composite members and shear bond strength between ordinary concrete and uhpc. in order to make reliable composite structures, it is very important to ensure sufficient interface strength. in this paper experimental data is presented, which was obtained from tests carried out by authors. the aim of experiments was to establish the influence of different heat treatment regimes on mechanical properties (including shear bond strength) of normal strength concrete and ultra-high performance concrete newly cast composite members. bi-surface shear test method was used to determine the average shear bond strength. three different curing regimes were analysed. it was observed from preliminary tests that after heat treatment uhpc achieved its final maturity, however ordinary concrete did not gain the same strength as concrete specimens which were cured in 20 °c water for 28 days. it is a possibility that shear bond strength of heat treated composite members was significantly reduced due to the large shrinkage deformations during the short period of time. the results presented in this paper make a significant contribution to supplement the limited information about possibilities to use normal strength concrete and uhpc in new nsc-uhpc composite structures. keywords: bi-surface shear test, shear bond strength, composite members, heat treatment, uhpc. ultra-high performance concrete usually is described as repair material with extraordinary mechanical properties and enhanced durability (afgc-setra 2013, harris et al. 2015, muñoz et al. 2014). service life of reinforced concrete structures is limited due to environment that exposes the structure, applied loads and etc., however partial use of uhpc has a potential to enhance exploitation time of reinforced concrete structures. application of uhpc is especially important in infrastructure components. nevertheless, understanding of material properties and structural behaviour is a major objective. the absence of uhpc structural design standards is one of the main problems in order to use this type of material in reliable manner. despite the fact that standardised bond strength measuring method between nsc and uhpc have not been developed yet, journal of sustainable architecture and civil engineering 2016/1/14 52 experiments were carried out by other researches (harris et al. 2015, muñoz et al. 2014, tayeh et al. 2013a, tayeh et al. 2013b) in order to measure the bond strength between ordinary concrete and uhpc. the existing methods (slant-shear test, push-off test, and splitting tensile test) according to astm 882, astm c1583, astm c496 were used to measure the bond strength, respectively. specimens surface preparation, concrete mix composition, optimal curing conditions are another relevant topics in order to compose reliable composite members. from the tests carried out by muñoz et al. (2014) it was determined that when the appropriate wetting conditions for substrate are achieved then the degree of surface roughness is not critical factor on the good bond strength between nsc and uhpc. however, simple surface treatment is necessary to apply in order to remove dusts and ensure excellent bond strength between composites. on purpose to determine the interfacial bond between nsc and uhpc, another experiments were carried out by tayeh et al. (2013a) and tayeh et al. (2013b). under the conditions described in (tayeh et al. 2013a, tayeh et al. 2013b), it was determined that appropriate preparation of old surface is necessary to ensure good bond strength between nsc and uhpc composites. mechanical bond is improved by applying surface preparation. nagaonkar and bhusari (2014) determined the bond strength between reactive powder concrete (rpc) and concrete (existing and fresh substrate). it was obtained higher bond strength for rpc and fresh concrete substrate. the conclusions were drawn that higher content of silica fume in rpc increases the bond strength between composites. despite the fact that relatively many experiments were carried out in order to determine the bond strength between old concrete substrate and new overlay of uhpc, it is still the lack of information about the shear bond strength between nsc and uhpc in new structures, taking into consideration the influence of different heat treatment regimes. it is also very important to determine the influence of heat treatment on another mechanical properties of ordinary concrete and uhpc when the objective is composite nsc-uhpc members. experimental program on this topic was carried out and the results of experiment are presented in this paper. methods bi-surface shear test on purpose to determine average shear bond strength between ordinary concrete and uhpc, bi-surface shear test method proposed by momayez et al. (2002) was used in this research. standard 150×150×150 mm moulds can be used in this method. in analysed case, which is presented in this paper, two-thirds (100 mm) of the mould was filled with ordinary concrete and one-third (50 mm) with uhpc. three thick steel plates with dimensions of 150×50×25 mm were used to make direct shear between interfaces of different concrete composites (momayez et al. 2002). constant load of 2 kn/s (santos et al. 2012) was applied for all bi-surface specimens. fig. 1 (a) scheme of bi-surface shear test, (b) example of bi-surface shear test when the objective is composite nsc-uhpc members. experimental program on this topic was carried out and the results of experiment are presented in this paper. methods bi-surface shear test on purpose to determine average shear bond strength between ordinary concrete and uhpc, bi-surface shear test method proposed by momayez et al. (2002) was used in this research. standard 150×150×150 mm moulds can be used in this method. in analysed case, which is presented in this paper, two-thirds (100 mm) of the mould was filled with ordinary concrete and one-third (50 mm) with uhpc. three thick steel plates with dimensions of 150×50×25 mm were used to make direct shear between interfaces of different concrete composites (momayez et al. 2002). constant load of 2 kn/s (santos et al. 2012) was applied for all bi-surface specimens. (a) (b) fig. 1. (a) scheme of bi-surface shear test, (b) example of bi-surface shear test heat treatment atmospheric steam curing is especially important in precast concrete industry. in order to increase the amount of production, curing time takes a significant role. after steam curing concrete gains higher strength in early age and the moulds can be soon used for other products (tikalsky and jonassen 2016). it is general recommendation do not exceed about 65 °c temperature when heat curing is applied for concrete in early age. high temperature accelerates concrete strength in early age, however influences on lower strength after 28 days or on ultimate strength (shetty 2013). as it is described in afgc-setra (2013), heat treatment applied to uhpfrc improves its mechanical properties. there are distinguished two different heat treatment regimes which can be applied to uhpfrc independently of one another. the first type of heat treatment can be called as heat curing and is applied during the first few hours after casting of concrete. the temperature of heat treatment has to be less than 65 °c on purpose to avoid delayed ettringite formation. the second type of heat treatment is applied when the concrete is hardened and the applied temperature has to be about 90 °c. from the point of view of composite structures, it is necessary that the temperature of heat treatment would be optimal for both composites – concrete and uhpc. in order to make comparisons, some of advantages and disadvantages of heat treated uhpc and not heat treated concrete are presented in table 1. it should be noted that the data presented in table 1 is general and actual properties can be different depending on specified case. table 1. advantages and disadvantages of heat treatment on concrete and uhpc (afgc-setra 2013; tikalsky and jonassen 2016, shetty 2013, skripkiūnas 2007) normal strength concrete – ultra high performance concrete composite members uhpc with heat treatment nsc without heat treatment advantages disadvantages advantages disadvantages reduced creep effect; total shrinkage equal to 0 after ht; after heat treatment specimens can be tested without waiting 28 days; about 10 % higher compressive and tensile strength; improved durability; higher early strength; higher energy costs; difficult to carry out and control the process; requires good knowledge; higher final strength of normal strength concrete when it is compared to steam cured concrete; avoids delayed ettringite formation; avoid internal cracking; lower energy costs; lower strength in early stage; higher creep effect; higher total shrinkage; 28 days until testing; not improved durability; a b 53 journal of sustainable architecture and civil engineering 2016/1/14 experiment heat treatment atmospheric steam curing is especially important in precast concrete industry. in order to increase the amount of production, curing time takes a significant role. after steam curing concrete gains higher strength in early age and the moulds can be soon used for other products (tikalsky and jonassen 2016). it is general recommendation do not exceed about 65 °c temperature when heat curing is applied for concrete in early age. high temperature accelerates concrete strength in early age, however influences on lower strength after 28 days or on ultimate strength (shetty 2013). as it is described in afgc-setra (2013), heat treatment applied to uhpfrc improves its mechanical properties. there are distinguished two different heat treatment regimes which can be applied to uhpfrc independently of one another. the first type of heat treatment can be called as heat curing and is applied during the first few hours after casting of concrete. the temperature of heat treatment has to be less than 65 °c on purpose to avoid delayed ettringite formation. the second type of heat treatment is applied when the concrete is hardened and the applied temperature has to be about 90 °c. from the point of view of composite structures, it is necessary that the temperature of heat treatment would be optimal for both composites – concrete and uhpc. in order to make comparisons, some of advantages and disadvantages of heat treated uhpc and not heat treated concrete are presented in table 1. it should be noted that the data presented in table 1 is general and actual properties can be different depending on specified case. table 1 advantages and disadvantages of heat treatment on concrete and uhpc (afgc-setra 2013; tikalsky and jonassen 2016, shetty 2013, skripkiūnas 2007) normal strength concrete – ultra high performance concrete composite members uhpc with heat treatment nsc without heat treatment advantages disadvantages advantages disadvantages _ reduced creep effect; _ total shrinkage equal to 0 after ht; _ after heat treatment specimens can be tested without waiting 28 days; _ about 10 % higher compressive and tensile strength; _ improved durability; _ higher early strength; _ higher energy costs; _ difficult to carry out and control the process; _ requires good knowledge; _ higher final strength of normal strength concrete when it is compared to steam cured concrete; _ avoids delayed ettringite formation; _ avoid internal cracking; _ lower energy costs; _ lower strength in early stage; _ higher creep effect; _ higher total shrinkage; _ 28 days until testing; _ not improved durability; the main mechanical properties of ordinary concrete are given in design standard en 1992-11:2004 (eurocode 2). ultra-high performance concrete is more recent material and there are no design standards, where would be possibility to find uhpc classification according to compressive strength and other mechanical properties. there are only interim recommendations for uhpfrc (afgc-setra, 2013). when it is necessary to obtain optimal mechanical properties of nsc-uhpc composite members, situation becomes even more complicated. in order to find the influence of heat treatment on mechanical properties of composite members and try to find optimal case, three different cases were analysed in this paper. concrete and uhpc mix compositions used in experiment are given in table 2 and table 3. journal of sustainable architecture and civil engineering 2016/1/14 54 all specimens were cast and tested according to available standards. geometry of the specimens to determine different mechanical properties were used as follows: compressive strength – cubes 100×100×100 mm, flexural tensile strength – prisms 100×100×400 mm, secant modulus of elasticity – prisms 100×100×300 mm, shear bond strength – cubes 150×150×150 mm. considering to the fact that the experiment was carried out in order to find the way how to produce new flexural composite members, it was chosen to cast both composites while they are in fresh condition (the second layer was cast during the first hour after the first layer was prepared). the surface between composites was left natural as it formed after vibration. the specimens were removed from moulds when passed 24 h hours after casting. material quantity, kg/m3 cement cem i 52.5 r 735 water 152 silica fume 99 glass powder 412 quartz sand (0/2 fr.) 962 superplasticizer 36.76 table 2 uhpc mix composition (w/c ratio 0.21) table 3 concrete mix composition (w/c ratio 0.47) material quantity, kg/m3 cement cem i 42.5 r 318 water 150 coarse aggregate (gravel 4/16 fr.) 960 fine aggregate (sand 0/4 fr.) 945 superplasticizer 1.91 on purpose to save costs the specimens were heat treated in 65 °c and 90 °c temperature water for 24 hours instead of 48 hours, then the device was turned off and the same time the specimens were left in hot water, while the temperature of water dropped down naturally. heat treated specimens were tested after 3 days from casting. scheme of experimental program is presented in fig. 2. fig. 2 scheme of experimental program results of concrete and uhpc average compressive strength are presented in table 4. it can be seen that the best compressive strength of concrete cubes was obtained when the specimens were cured in 20 °c water for 28 days period. the concrete specimens which were heat treated in 65 °c and 90 °c temperature water showed lower values of compressive strength 25.92 % and 33.14 %, respectively. it should be noted that both c-c-65ht and c-c-90ht series of specimens experiment the main mechanical properties of ordinary concrete are given in design standard en 1992-1-1:2004 (eurocode 2). ultrahigh performance concrete is more recent material and there are no design standards, where would be possibility to find uhpc classification according to compressive strength and other mechanical properties. there are only interim recommendations for uhpfrc (afgc-setra, 2013). when it is necessary to obtain optimal mechanical properties of nsc-uhpc composite members, situation becomes even more complicated. in order to find the influence of heat treatment on mechanical properties of composite members and try to find optimal case, three different cases were analysed in this paper. concrete and uhpc mix compositions used in experiment are given in table 2 and table 3. table 2. uhpc mix composition (w/c ratio 0.21) table 3. concrete mix composition (w/c ratio 0.47) material quantity, kg/m3 material quantity, kg/m3 cement cem i 52.5 r 735 cement cem i 42.5 r 318 water 152 water 150 silica fume 99 coarse aggregate (gravel 4/16 fr.) 960 glass powder 412 fine aggregate (sand 0/4 fr.) 945 quartz sand (0/2 fr.) 962 superplasticizer 1.91 superplasticizer 36.76 all specimens were cast and tested according to available standards. geometry of the specimens to determine different mechanical properties were used as follows: compressive strength – cubes 100×100×100 mm, flexural tensile strength – prisms 100×100×400 mm, secant modulus of elasticity – prisms 100×100×300 mm, shear bond strength – cubes 150×150×150 mm. considering to the fact that the experiment was carried out in order to find the way how to produce new flexural composite members, it was chosen to cast both composites while they are in fresh condition (the second layer was cast during the first hour after the first layer was prepared). the surface between composites was left natural as it formed after vibration. the specimens were removed from moulds when passed 24 h hours after casting. on purpose to save costs the specimens were heat treated in 65 °c and 90 °c temperature water for 24 hours instead of 48 hours, then the device was turned off and the same time the specimens were left in hot water, while the temperature of water dropped down naturally. heat treated specimens were tested after 3 days from casting. scheme of experimental program is presented in fig. 2. fig. 2. scheme of experimental program experimental program no heat treatment (nht): specimens cured in 20 °c water and tested after 28 days; heat treatment at 65 °c (65ht): specimens heat treated in 65 °c temperature water for (24+24) hours, and tested after 3 days from casting; heat treatment at 90 °c (90ht): specimens heat treated in 90 °c temperature water for (24+24) hours, and tested after 3 days from casting; tested mechanical properties  normal strength concrete (c) and uhpc (u) specimens: compressive strength (c); flexural tensile strength (fl) secant modulus of elasticity (e);  normal strength concrete (c) and nsc-uhpc (cu) composite members shear bond strength (b); results 55 journal of sustainable architecture and civil engineering 2016/1/14 with the same mix composition were tested after 3 days from casting. therefore, 7.22 % difference between results shows that the temperature of heat treatment has some influence on the values of mechanical properties. however, two interpretations of results can be distinguished when it is compared to reference specimens. the first interpretation can be defined that the loss of strength was due to high temperature, and microstructure of concrete was damaged. in the second case it can be stated that heat treated specimens were tested after 3 days from casting and the strength of cubes after heat treatment was only about 60–75 % of cubes which were tested after 28 days, and later the strength will increase. however, it can be found in literature (tikalsky and jonassen 2016, shetty 2013, skripkiūnas 2007) that concrete specimens heat treated at high temperature have higher early strength of concrete, but the final strength is lower than for the specimens which where cured 28 days in normal conditions. in any case the strength of concrete in early period of composite nsc-uhpc structural member would be lower than reference specimen c-c-nht. this is some disadvantage, because uhpc after heat treatment reach its final maturity without waiting 28 days (afgc-setra, 2013). under the conditions of analysed case, the influence of heat treatment temperature on average compressive strength of uhpc cubes was especially insignificant. when compare to reference cubes c-u-nht, the strength of c-u-65ht and c-u-65ht cubes were 1.14 % and 0.96 % higher, respectively. however, it should be noted that another mechanical properties of concrete would be better after heat treatment at high temperature (zero total shrinkage, reduced creep, increased durability (afgc-setra, 2013)). specimen type average fcm, mpa standard deviation, mpa cov, % specimen type average fcm, mpa standard deviation, mpa cov, % c-c-nht 52.27 (100) 3.143 6.014 c-u-nht 145.33 (100) 3.71 2.55 c-c-65ht 38.72 (74.08) 0.79 2.03 c-u-65ht 146.97 (101.14) 10.21 6.95 c-c-90ht 34.95 (66.86) 0.43 1.24 c-u-90ht 146.73 (100.96) 7.97 5.43 table 4 compressive strength of concrete and uhpc at different heat treatment regimes the results of average flexural tensile strength are presented in table 5. flexural tensile strength of ordinary concrete prisms was lower when heat treatment was applied. in comparison with reference specimen without heat treatment the strength of fl-c-65ht and fl-c-90ht was lower 19.47 % and 28.6 %, respectively. the difference between heat treated specimens was 9.13 % when compare to reference specimens. under this experiment conditions flexural tensile strength of uhpc prisms, that where heat treated in 65 °c temperature water showed the lowest values when compare to fl-u-nht and fl-u-90ht specimens. due to a reason to find optimal curing conditions for both type of composites (concrete and uhpc), this type of heat treatment was applied after the concrete has set. according to afgc-setra (2013), heat treatment at 65 °c is applied at the moment when uhpc starts to set and its aim is to accelerate initial hardening. it is a possibility that the applied temperature was enough to reach compressive strength of uhpc similar to another two cases (c-u-nht and c-u-90ht), however the final maturity in tension was not reached at this temperature. the difference of flexural tensile strength between the specimens which were heat treated in 90 °c temperature water and cured 28 days in water was insignificant – 0.3 %. *explanations of abbreviations are given in fig. 2. journal of sustainable architecture and civil engineering 2016/1/14 56 similar to compressive strength tendencies were observed with secant modulus of elasticity. for ordinary concrete the higher the temperature was applied the lower secant modulus of elasticity was obtained. however, different interpretations of results can be stated as discussed above about the compressive strength of concrete. the differences between secant modulus of elasticity of uhpc in all three analysed cases were insignificant. comparison of results is given in table 6. table 5 flexural tensile strength of concrete and uhpc at different heat treatment regimes *explanations of abbreviations are given in fig. 2. specimen type average fctm,fl, mpa standard deviation, mpa cov, % specimen type average fctm,fl, mpa standard deviation, mpa cov, % fl-c-nht 5.70 (100) 0.38 6.62 fl-u-nht 16.71 (100) 1.40 8.35 fl-c-65ht 4.59 (80.53) 0.17 3.70 fl-u-65ht 14.46 (86.54) 0.33 2.25 fl-c-90ht 4.07 (71.40) 0.16 4.05 fl-u-90ht 16.66 (99.70) 0.90 5.43 specimen type average ecm, gpa standard deviation, gpa cov, % specimen type average ecm, gpa standard deviation, gpa cov, % e-c-nht 29.85 (100) 0.79 2.65 e-u-nht 41.31 (100) 0.82 1.97 e-c-65ht 29.28 (98.09) 0.63 2.14 e-u-65ht 42.52 (102.93) 0.08 0.18 e-c-90ht 26.07 (87.33) 0.23 0.87 e-u-90ht 41.26 (99.88) 0.02 0.05 *explanations of abbreviations are given in fig. 2. table 6 secant modulus of elasticity of concrete and uhpc at different heat treatment regimes the most important aim and practical application of experiment were to ensure the sufficient shear bond strength in the plane between concrete and uhpc in newly cast flexural composite nsc-uhpc members, and achieve optimal concrete and uhpc mechanical properties. there are a lot of different factors, which have influence on shear bond strength between different composites, therefore, due to this reason it is difficult to distinguish what is the influence of heat treatment and how many influence have another factors. the example of flexural composite nsc-uhpc member is presented in fig. 3. it should be noted that the position of layers in the cross-section could be different (uhpc in compression zone, in both zones, etc.). fig. 3 flexural composite nscuhpc member similar to compressive strength tendencies were observed with secant modulus of elasticity. for ordinary concrete the higher the temperature was applied the lower secant modulus of elasticity was obtained. however, different interpretations of results can be stated as discussed above about the compressive strength of concrete. the differences between secant modulus of elasticity of uhpc in all three analysed cases were insignificant. comparison of results is given in table 6. table 6. secant modulus of elasticity of concrete and uhpc at different heat treatment regimes specimen type average ecm, gpa standard deviation, gpa cov, % specimen type average ecm, gpa standard deviation, gpa cov, % e-c-nht 29.85 (100) 0.79 2.65 e-u-nht 41.31 (100) 0.82 1.97 e-c-65ht 29.28 (98.09) 0.63 2.14 e-u-65ht 42.52 (102.93) 0.08 0.18 e-c-90ht 26.07 (87.33) 0.23 0.87 e-u-90ht 41.26 (99.88) 0.02 0.05 *explanations of abbreviations are given in fig. 2. the most important aim and practical application of experiment were to ensure the sufficient shear bond strength in the plane between concrete and uhpc in newly cast flexural composite nsc-uhpc members, and achieve optimal concrete and uhpc mechanical properties. there are a lot of different factors, which have influence on shear bond strength between different composites, therefore, due to this reason it is difficult to distinguish what is the influence of heat treatment and how many influence have another factors. the example of flexural composite nsc-uhpc member is presented in fig. 3. it should be noted that the position of layers in the cross-section could be different (uhpc in compression zone, in both zones, etc.). fig. 3. flexural composite nsc-uhpc member composite nsc-uhpc specimens which were used in experiment are presented in fig. 4., before testing (a) and after testing (b) and (c). in comparison to composite cubes, continuous specimens made from ordinary concrete also were cast and specimen after failure is presented in fig. 4 (d). (a) (b) (c) (d) fig. 4. (a) composite specimens, (b) and (c) composite specimens after failure, (d) continuous concrete cube after failure as it was preliminary supposed, the average shear bond strength of continuous concrete specimens in all cases was higher than the bond strength in shear of composite members. the results of shear bond strength are presented in table 7. for continuous concrete specimens almost the same influence of different heat treatment regimes as for compressive concrete 57 journal of sustainable architecture and civil engineering 2016/1/14 composite nsc-uhpc specimens which were used in experiment are presented in fig. 4., before testing (a) and after testing (b) and (c). in comparison to composite cubes, continuous specimens made from ordinary concrete also were cast and specimen after failure is presented in fig. 4 (d). fig. 4 (a) composite specimens, (b) and (c) composite specimens after failure, (d) continuous concrete cube after failure similar to compressive strength tendencies were observed with secant modulus of elasticity. for ordinary concrete the higher the temperature was applied the lower secant modulus of elasticity was obtained. however, different interpretations of results can be stated as discussed above about the compressive strength of concrete. the differences between secant modulus of elasticity of uhpc in all three analysed cases were insignificant. comparison of results is given in table 6. table 6. secant modulus of elasticity of concrete and uhpc at different heat treatment regimes specimen type average ecm, gpa standard deviation, gpa cov, % specimen type average ecm, gpa standard deviation, gpa cov, % e-c-nht 29.85 (100) 0.79 2.65 e-u-nht 41.31 (100) 0.82 1.97 e-c-65ht 29.28 (98.09) 0.63 2.14 e-u-65ht 42.52 (102.93) 0.08 0.18 e-c-90ht 26.07 (87.33) 0.23 0.87 e-u-90ht 41.26 (99.88) 0.02 0.05 *explanations of abbreviations are given in fig. 2. the most important aim and practical application of experiment were to ensure the sufficient shear bond strength in the plane between concrete and uhpc in newly cast flexural composite nsc-uhpc members, and achieve optimal concrete and uhpc mechanical properties. there are a lot of different factors, which have influence on shear bond strength between different composites, therefore, due to this reason it is difficult to distinguish what is the influence of heat treatment and how many influence have another factors. the example of flexural composite nsc-uhpc member is presented in fig. 3. it should be noted that the position of layers in the cross-section could be different (uhpc in compression zone, in both zones, etc.). fig. 3. flexural composite nsc-uhpc member composite nsc-uhpc specimens which were used in experiment are presented in fig. 4., before testing (a) and after testing (b) and (c). in comparison to composite cubes, continuous specimens made from ordinary concrete also were cast and specimen after failure is presented in fig. 4 (d). (a) (b) (c) (d) fig. 4. (a) composite specimens, (b) and (c) composite specimens after failure, (d) continuous concrete cube after failure as it was preliminary supposed, the average shear bond strength of continuous concrete specimens in all cases was higher than the bond strength in shear of composite members. the results of shear bond strength are presented in table 7. for continuous concrete specimens almost the same influence of different heat treatment regimes as for compressive concrete as it was preliminary supposed, the average shear bond strength of continuous concrete specimens in all cases was higher than the bond strength in shear of composite members. the results of shear bond strength are presented in table 7. for continuous concrete specimens almost the same influence of different heat treatment regimes as for compressive concrete specimens can be observed. heat treated specimens had lower strength, but the lowest one in this case was not achieved at the highest temperature. however, this could be explained due to the relatively large scatter of results in bond shear strength, coefficient of variation is up to 18.06 %. it is more difficult to analyse the results of composite nsc-uhpc specimens, because there are many factors which can do influence on strength in shear plane between composites. surface roughness, different curing conditions, different shrinkage deformations and difference between secant modulus of elasticity play significant role on shear bond strength of composite members (santos and júlio 2010). under this experiment conditions, the best results were obtained for composite specimens without heat treatment and the average shear bond strength was equal to 5.01 mpa. it was taken as reference specimen. the specimens which were heat treated in 65 °c and 90 °c temperature had lower strength than reference specimen 62.87 % and 60.48 %, respectively. it should be noted that in all three cases the scatter of results was large. coefficient of variation was 38.30 %, 43.40 % and 27.62 %, respectively. this could be explained that the influence of heat treatment on shear bond strength in early period of composite nsc-uhpc is a partial. specimen type average τ, mpa standard deviation, mpa cov, % failure mode specimen type average τ, mpa standard deviation, mpa cov, % failure mode b-c-nht 10.30 (100) 0.83 8.05 2 planes 1 plane 1 plane b-cu-nht 5.01 (100) 1.92 38.30 interface 2 planes interface b-c-65ht 7.91 (76.80) 1.43 18.06 2 planes 1 plane 2 planes b-cu-65ht 1.86 (37.13) 0.81 43.40 interface interface interface b-c-90ht 8.52 (82.72) 0.51 6.00 1 plane 1 plane 1 plane b-cu-90ht 1.98 (39.52) 0.55 27.62 interface interface interface table 7 shear bond strength of concrete and concreteuhpc composite members at different heat treatment regimes *explanations of abbreviations are given in fig. 2. a b c d journal of sustainable architecture and civil engineering 2016/1/14 58 1 the results of carried out experiments can be described in two different interpretations. in the first case, it could be stated that after heat treatment in 65 °c and 90 °c temperature water, the mechanical properties of ordinary concrete specimens were negatively affected in comparison to specimens cured in 20 °c water for 28 days. in the second case, it could be stated that after heat treatment ordinary concrete specimens were tested after 3 days from casting, therefore the concrete did not reach its final maturity and the strength after 28 days will be similar as for non-heat treated specimens. however, it can be seen some differences in strength at different temperatures (65 °c and 90 °c). the lower strength at higher temperature. testing after 3 days were chosen in order to check a possibility to use concrete-uhpc composite members without waiting for 28 days. as it is described in afgc-setra (2013) recommendations, uhpc reaches its final maturity after heat treatment in 90 °c. on purpose to draw more clear conclusions, it is necessary to cast additional concrete specimens, then after heat treatment in 65 °c and 90 °c temperature wait up to 28 days until testing and make the comparisons. 2 from the point of view of composite nsc-uhpc members it is difficult to define optimal curing conditions, however without heat treatment uhpc lose some advantages. also it is a possibility that flexural composite concrete-uhpc members without heat treatment would have larger long-term deformations in comparison to heat treated members. 3 negative influence of heat treatment on shear bond strength between concrete and uhpc could be partly explained due to the large shrinkage deformations during the short period of time. however, the scatter of results was significantly large, therefore it means that the influence of heat treatment is only a partial and it is difficult to distinguish it from other factors contribution. conclusions references afgc-setra. ultra-high performance fibre-reinforced concretes – interim recommendations, france, 2013. en 1992-1-1:2004. eurocode 2: design of concrete structures – part 1-1: general rules and rules for buildings. habel, k. structural behaviour of elements combining ultra-high performance fibre reinforced concretes (uhpfrc) and reinforced concrete. doctoral thesis no. 3036, ecole polytechnique fédérale de lausanne (epfl), 2004. harris d.k., muñoz m.a.c., gheitasi a., ahlborn t.m., rush s.v. the challenges related to interface bond characterization of ultra-high-performance concrete with implications for bridge rehabilitation practices. advances in civil engineering materials, 2015; 4(2): 1–27. http://dx.doi:10.1520/acem20140034 momayez a., ramezanianpour a., rajaie h., ehsani m.r. experimental investigation of the methods of evaluating the bond strength between concrete substrate and repair materials. international journal of engineering, transactions b: applications, 2002; 15(4): 319-332. momayez a., ramezanianpour a.a., rajaie h., ehsani m.r. bi-surface shear test for evaluating bond between existing and new concrete. aci materials journal, 2004; 101(2): 99-106. momayez a., ehsani m.r., ramezanianpour a.a., rajaie h. comparison of methods for evaluating bond strength between concrete substrate and repair materials. cement and concrete research, 2005; 35(4): 748-757. muñoz c.m., harris, d., ahlborn t., froster d. bond performance between ultrahigh-performance concrete and normal-strength concrete. journal of materials in civil engineering, 2014; 26(8). http:// dx.doi.org/10.1061/(asce)mt.1943-5533.0000890 nagaonkar d.s., and. bhusari j.p. characterization of reactive powder concrete with respect to its bond strength. international journal of scientific & engineering research, 2014; 5(5): 279-282. santos d.s., santos p.m.d., dias-da-costa d. effect of surface preparation and bonding agent on the concrete-to-concrete interface strength. construction and building materials, 2012; 37: 102-110. http://dx.doi.org/10.1016/j.conbuildmat.2012.07.028 santos p.m.d., júlio, e.n.b.s. recommended improvements to current shear-friction provisions of model code. in: 3rd fib international congress, washington, dc, may 29–june 02, 2010. 59 journal of sustainable architecture and civil engineering 2016/1/14 shetty m.s. concrete technology: theory and practice (7 ed.). india: s. chand & company pvt. ltd.; 2013. skripkiūnas g. statybinių konglomeratų struktūra ir savybės. kaunas: vitae litera; 2007. tayeh b.a., bakar b.h.a., johari m.a.m. characterization of the interfacial bond between old concrete substrate and ultra high performance fiber concrete repair composite. materials and structures, 2013a; 46(5), 743-753. doi: 10.1617/s11527-012-9931-1 tayeh b.a., bakar b.h.a., johari m.a.m., voo y.l. evaluation of bond strength between normal concrete substrate and ultra high performance fiber concrete as a repair material. procedia engineering, 2013b; 54: 554-563. http://dx.doi.org/10.1016/j.proeng.2013.03.050 tikalsky p.j., jonassen d. available on internet [2016-05-16]: http://www.engr.psu.edu/ce/courses/ce584/concrete/library/construction/curing/accelerating%20 strength%20gain.htm tadas zingila phd student kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area strength, stability and serviceability of reinforced concrete and uhpfrc structures. address studentu st. 48, lt-51367, kaunas, lithuania e-mail: tadas.zingaila@ ktu.edu mindaugas augonis assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area durability of engineering structures, strength and stability of reinforced concrete structures address studentu st. 48, lt-51367, kaunas, lithuania e-mail: mindaugas. augonis@ktu.lt evaldas šerelis dr. assistant kaunas university of technology, faculty of civil engineering and architecture, department of building materials main research area ultra-high performance concrete address studentu st. 48, lt-51367, kaunas, lithuania e-mail: evaldas.serelis@ ktu.lt šarūnas kelpša assistant kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area strength, stability and serviceability of reinforced concrete structures. address studentu st. 48, lt-51367, kaunas, lithuania e-mail: sarunas.kelpsa@ ktu.lt deividas martinavičius master’s degree student kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area calculation and analysis of building structures. address studentu st. 48, lt-51367, kaunas, lithuania e-mail: deividas. martinavicius@ ktu.edu about the authors 59 journal of sustainable architecture and civil engineering 2015/2/11 jsace 2/11 journal of sustainable architecture and civil engineering vol. 2 / no. 11 / 2015 pp. 59-71 doi 10.5755/j01.sace.11.2.12606 © kaunas university of technology received 2015/01/25 accepted after revision 2015/06/01 assessment of buildings with ventilated facade systems and evaluation of point thermal bridges assessment of buildings with ventilated facade systems and evaluation of point thermal bridges jolanta šadauskienė*, lina šeduikytė faculty of civil engineering and architecture, kaunas technology university studentu str. 48, lt51367, kaunas, lithuania juozas ramanauskas faculty of civil engineering and architecture, kaunas technology university studentu str. 48, lt51367, kaunas, lithuania institute of architecture and construction of kaunas university of technology tunelio str. 60, lt-44405, kaunas, lithuania andrius buska rockwool uab, a.gostauto str. 40b, lt-01112 vilnius, lithuania analyzes of influence of the point thermal bridges of buildings with ventilated facade systems on the thermal properties of envelops are presented in the paper. the relation between the separate components of the envelop were made: thermal properties and thickness of supporting wall’s layer; value of thermal conductivity and thickness of insulation layer. studies have shown, that the value of the point thermal transmittance, which depended on the thermal properties of the envelop and thickness of the layers, might increase to 35%. the higher thermal conductivity coefficient of the material of the supporting wall and thickness of the insulation layer, the larger value the point thermal transmittance. and contrary, if the thickness of the supporting wall and coefficient of thermal conductivity of insulation layer was increased, the value the point thermal transmittance was decreased. it is possible to determine the value of thermal bridges of certain construction design solution by simplified calculations, according to the existing dependencies formulas or graphics. in this case it’s necessary to have dependence of the point thermal bridges from thermal insulation properties and dimensions of envelop layers. keywords: thermal bridges, thermal conductivity, supporting wall, thermal insulation. *corresponding author: jolanta.sadauskiene@ktu.lt http://dx.doi.org/10.5755/j01.sace.11.2.12606 journal of sustainable architecture and civil engineering 2015/2/11 60 in order to implement european energy performance of buildings directive (epbd) requirements, for the reduction of energy consumption, several national requirements in european countries are created for thermal properties of building envelops, as well as calculation methodologies for evaluation of energy efficiency performance of buildings. each european country presents they own methodology for building energy efficiency performance (din v 18599 in germany, docet in italy, calener in spain, ns 3034 in norway, etc.), which is based on identification of factors which are increasing building energy losses. one of such factors are building thermal bridges, which are appearing because of full or partial penetration of the building envelope by materials with a different thermal conductivity, and/or a change in thickness of the fabric, and/or a difference between internal and external areas, such as occur at wall/floor/ceiling junctions. literature review shows, that the total impact of thermal bridges on the heating energy need is in general considerable and can vary from 5 % to 39 % (theodosiou and papadopoulos 2008; citteio and et al. 2008, evola and et al. 2011.). this depends on several factors such as weather conditions, level of insulation, the thermal bridges constructive solution, type of building (use and geometry) and of the method used to implement its effect within the calculation of the building energy demand (martin and et al. 2011, ascione and et al. 2014, ge and et al. 2013, cappelleti and et al. 2011, theodosiou and et al. 2014). thermal bridges can affect a single point, a linear area or a spatial configuration. usually, in the calculation of the building energy demand liner thermal bridges are evaluated, which occurs at the junction between two or more elements of the building envelope. it’s easy, as in most cases values of liner thermal transmittance (ψ-value) of standard parts are presented in thermal bridge atlases (capozzoli and et al. 2013). the most common atlas is represented by the european standard en iso 14683, witch contains seventy-six cases referring to eight typologies of thermal bridges (roofs, corners, intermediate floors, internal walls, slab-on-ground floors, suspended ground floors, pillars, window and door openings). however, when assessment of point thermal bridges is made, they influence on the total energy balance of the building is more complicated. that’s why the effect of the point thermal bridges is often neglected in the analyses aimed at defining the building energy efficiency performance. however, it’s an important factor when projects on low energy buildings are made. studies are showing, that if continuous metal profiles are used for fixing thermal insulation layer, and profiles are crossing the insulation layer, the thermal resistance could decrease twice (gomes and et al. 2013, qasass and et al. 2014). if these additional heat losses through the thermal bridges are not evaluated or evaluated incorrectly, the owner of the building could feel deceived because of incorrect building energy efficiency performance declaration. furthermore, problems because of selection of proper power for the heating system might appear. in this case, under extreme temperature differences between the outside and inside temperatures, required indoor thermal conditions might not be ensured. because of low surface temperatures, this will result in moisture condensation and mold growth at the places of thermal bridges (angelis and serra 2014). the aim of this work was to determine the point thermal transmittance (χ-value) of the fixing elements, which were made from aluminum. as well as setting of dependence from the thickness of insulation layer, from coefficient of thermal conductivity of insulation material and from the type and thickness of the supporting wall (brick masonry, monolith, frame structure and ctr.). introduction calculation of thermal transmittance value through building elements and thermal bridges the calculation of the transmission heat transfer coefficient includes the contribution due to thermal bridges, according to eq. 1: methodology 61 journal of sustainable architecture and civil engineering 2015/2/11 thermal bridges may be defined according to en iso 10211. the linear thermal transmittance of the thermal bridges (ψ) is calculated as in eq. 2: hd = σi ai ∙ ui + σk lk ∙ ψk + σj χj; where: a i – is the area of element i of the building envelope, in m2; u i – is the thermal transmittance of element i of the building envelope, in w/(m2∙k); l k – is the length of where: l2d – is the linear thermal coupling coefficient obtained from a twodimensional calculation of the component separating the two environments being where: l 3d – is the thermal coupling coefficient obtained from a 3-d calculation of the 3-d component separating the two environments being considered; u j – is the where: h 0 – specific heat losses through the repeated area of the envelop with fixing element, w/k; h – specific heat losses (1) (2) (3) (4) linear thermal bridge k, in m; ψ k – is the linear thermal transmittance of linear thermal bridge k, in w/(m∙k); χ j – is the point thermal transmittance of the point thermal bridge j, in w/k. calculations of u-values follow (str 2.05.01:2013) linear thermal transmittance values depend on the system of dimensions used in calculating the areas of one-dimensional heat flow (i.e. in the calculation of σu j ∙ l j ). but the total transmission heat transfer coefficient h d ( eg.1) has to evaluate all thermal bridges, it means that not only linear but also point thermal bridges have to be evaluated. in general, the influence of point thermal bridges (insofar as they result from the intersection of linear thermal bridges) can be neglected and so the correction term involving point thermal bridges can be omitted from equation (1). if, however, there are significant point thermal bridges, then the point thermal transmittances should be calculated in accordance with iso 10211. the point thermal transmittance (value-χ) is calculated as in eq. 3: ψ = l2d – σuj ∙ lj considered; u j – is the thermal transmittance of the one-dimensional component j separating the two environments being considered; l j – is the length within the two-dimensional geometrical model over which the value of u j applies. when the point thermal transmittance (χ-value) of fixing elements is determined by 3-d methodology, then specific heat losses through the repeated area of the envelop with fixing element h and without fixing element h 0 are calculated. the difference of these specific heat losses show the value of the point thermal transmittance (eq. 4) thermal transmittance of the 1-d component i separating the two environments being considered; a i – is the area over which the value u i applies; ψ j – are linear thermal transmittances; l j – is the length over which the value of ψ j applies; n j – is the number of 2-d components; n i – is the number of 1-d components. χ = h h0 through the repeated area of the envelop without fixing element, w/k. journal of sustainable architecture and civil engineering 2015/2/11 62 since fi xing elements are crossing insulation layer in local arias, they infl uence on heat transfer is evaluated by point thermal transmittance coeffi cient χ, w/k. if these point thermal bridges are repetitive in the envelop, they could be evaluated as supplement of the heat transmittance coeffi cient δu (eq. 5), taking into account they number in 1 m2 of the envelop. if the density of the fi xing elements is typical for the certain area of the envelop, it is possible to specify envelope’s heat transmittance coeffi cient u, w/(m2∙k) at once (eq. 6). where: n – the number of the fi xing elements per area, number./m2. where: u o – heat transmittance coeffi cient of the envelope, without evaluation of the impact of the fi xing elements, w/(m2∙k). (5) (6) assessment of the point thermal bridges ventilated facades with aluminum fi xing elements were chosen for the calculations (fig. 1.). δu = χ ∙ n u = uo + δu  fig. 1 the principal scheme of the ventilated facades with aluminum fixing elements: a) top view; b) side view. 1 – supporting wall; 2 – thermal insulation layer; 3 – wind insulation layer; 4 – gasket; 5 – aluminum fixing elements; 6 – ventilated air gap; 7– facade panel fig. 2 calculation scheme of the thermal bridge of fixing element a b fixing elements’ material is aluminum, wall thickness was 3 mm, width 40 mm. fixing elements’ to masonry wall were fi xed through the plastic 5mm width gasket. the distance between axis of aluminum system’s elements was 600 mm in horizontal and vertical planes. typical element of this wall was 600×600 mm according to the symmetry axis, with fi xing element in the middle (fig. 2). the area of such element was 0.36 m2, and the number of fi xing element in 1 m2 of the envelope’s area was : n = 2.778 vnt./m2. three dimensional temperature fi eld calculation program heat 3 was used in order to determine point thermal transmittance (χ-value) of aluminum fi xing element and dependence of this value on the construction’s materials. with this program diff erent variation of constructions were calculated. variations are presented in table 1. for the analyses of point thermal bridges basic construction variant was selected: thickness of the supporting wall d l = 200 mm, thermal conductivity of the supporting wall λ l = 0.5 w/(m∙k), thickness of the insulation layer d t = 150 mm, thermal conductivity of the insulation layer λ t = 0.034 w/(m∙k). 63 journal of sustainable architecture and civil engineering 2015/2/11 statistical evaluation regression analysis were made in order to determine empirical dependence and relation between the point thermal transmittance (value-χ) and properties of construction materials, reliability and adequacy of calculation results. the dependent variable was the point thermal transmittance (value-χ), interval variables were thermal conductivity coefficients of the supporting wall and insulation layer. correlation coefficient r was used for the evaluation of the strength of connection of variables. pearson statistics and significance level of α = 0.05 was used for the evaluation. the linear regression model was evaluated according to the value of the determination coefficient r2, according to anova p-value <0.05, according to vif ≤ 4 (no multicolinearity problems), according to all cook’s values ≤ 1, according to compliance to correlation of signs of coefficients, according to standardized residual errors and p-p graphic. var. of calculation thickness of the layer of the supporting wall, d l , mm thermal conductivity of the layer of the supporting wall, λ l , (w/ m∙k) thickness of the insulation layer, d t , mm thermal conductivity of the insulation layer l t , (w/ m∙k) basic data 200 0.5 150 0.034 1 200 0.1 ÷ 1 150 0.034 2 50 ÷ 500 0.5 150 0.034 3 200 0.5 150 0.030 ÷ 0.040 4 200 0.5 100 ÷ 200 0.034 table 1 variations of calculated parameters behavior of the thermal flow through the pint thermal bridge three-dimensional temperature field simulation was made in order to determine the influence of the point thermal bridge to the behavior of thermal flow in the external wall of the building, with basic data of the envelop (fig. 3). thermal flow in the place of the thermal bridge is no smooth and parallel. in the warm part of insulation layer, the direction of the thermal flow is not only from the inner face, but also from the surrounding thermal insulation material. respectively, in the cold part of the insulation layer, the direction of the thermal flow is not only to the external part, but to the thermal insulation results fig. 3 behavior of the thermal flow through the pint thermal bridge for the analyses of point thermal bridges basic construction variant was selected: thickness of the supporting wall dl = 200 mm, thermal conductivity of the supporting wall λl = 0.5 w/(m∙k), thickness of the insulation layer dt = 150 mm, thermal conductivity of the insulation layer λt = 0.034 w/(m∙k). 2.2. statistical evaluation regression analysis were made in order to determine empirical dependence and relation between the point thermal transmittance (value-χ) and properties of construction materials, reliability and adequacy of calculation results. the dependent variable was the point thermal transmittance (value-χ), interval variables were thermal conductivity coefficients of the supporting wall and insulation layer. correlation coefficient r was used for the evaluation of the strength of connection of variables. pearson statistics and significance level of α = 0.05 was used for the evaluation. the linear regression model was evaluated according to the value of the determination coefficient r2, according to anova p-value <0.05, according to vif ≤ 4 (no multicolinearity problems), according to all cook's values ≤ 1, according to compliance to correlation of signs of coefficients, according to standardized residual errors and p-p graphic. 3. results 3.1 behavior of the thermal flow through the pint thermal bridge three-dimensional temperature field simulation was made in order to determine the influence of the point thermal bridge to the behavior of thermal flow in the external wall of the building, with basic data of the envelop (fig. 3). fig. 3. behavior of the thermal flow through the pint thermal bridge thermal flow in the place of the thermal bridge is no smooth and parallel. in the warm part of insulation layer, the direction of the thermal flow is not only from the inner face, but also from the surrounding thermal insulation material. respectively, in the cold part of the insulation layer, the direction of the thermal flow is not only to the external part, but to the thermal insulation material as well. depending on the material of the supporting wall, depends the capacity of the thermal flow to gather (on the cold side) or to disperse (on the worm side). the results of the movement of thermal flow are presented in fig. 4. the results show, that if thermal conductivity of the material of the supporting wall, from the warm part of the insulation layer, is high, then there are conditions for the concentration of the high thermal flow at the place of the pint thermal bridge, close to insulation layer. heat-conductive materials, which were located at the cold part of the insulation layer, and developed surfaces of the fixing elements are creating conditions for the dispersion of the thermal flow. therefore, the value of the point thermal transmittance will be higher. supporting wall thermal insulation material as well. depending on the material of the supporting wall, depends the capacity of the thermal flow to gather (on the cold side) or to disperse (on the worm side). the results of the movement of thermal flow are presented in fig. 4. the results show, that if thermal conductivity of the material of the supporting wall, from the warm part of the insulation layer, is high, then there are conditions for the concentration of the high thermal flow at the place of the pint thermal bridge, close to insulation layer. heat-conductive matejournal of sustainable architecture and civil engineering 2015/2/11 64 rials, which were located at the cold part of the insulation layer, and developed surfaces of the fixing elements are creating conditions for the dispersion of the thermal flow. therefore, the value of the point thermal transmittance will be higher. the obtained results show, that the fixing elements of the buildings with ventilated facade systems are going through the insulation layer and they have higher thermal conductivity compared with insulation layer. that’s why there were high thermal flows in the intersection part and the effectiveness of thermal transmittance was increased. the point thermal transmittance (χ-value) depends on the type and material of the fixing element, as well as on the properties of the other construction materials: on the thermal conductivity and thickness of the insulation layer as well as on the thermal conductivity and thickness of the supporting wall. evaluation of the dependency of thermal bridge fig. 5 presents dependence of the point thermal transmittance (χ-value) of the fixing element from the thermal conductivity of the supporting wall (1st var., table 1). if the thermal conductivfig. 4 thermal flow with different thermal conductivity of the layer of the supporting wall: a) λ l = 0.1 w/ m∙k; b) λ l = 0.5 w/ m∙k; c) λ l = 1 w/ m∙k; 1 – supporting wall; 2 – thermal insulation layer a b c fig. 4. thermal flow with different thermal conductivity of the layer of the supporting wall: a) λl = 0.1 w/ m∙k; b) λl = 0.5 w/ m∙k; c) λl = 1 w/ m∙k; 1 – supporting wall; 2 – thermal insulation layer. the obtained results show, that the fixing elements of the buildings with ventilated facade systems are going through the insulation layer and they have higher thermal conductivity compared with insulation layer. that’s why there were high thermal flows in the intersection part and the effectiveness of thermal transmittance was increased. the point thermal transmittance (χ-value) depends on the type and material of the fixing element, as well as on the properties of the other construction materials: on the thermal conductivity and thickness of the insulation layer as well as on the thermal conductivity and thickness of the supporting wall. 3.2 evaluation of the dependency of thermal bridge fig. 5 presents dependence of the point thermal transmittance (χ-value) of the fixing element from the thermal conductivity of the supporting wall (1st var., table 1). if the thermal conductivity value λl of the supporting wall is increased, the influence of the point thermal transmittance (χ-value) to the total envelope’s heat transmittance is increased by logarithmic distribution. results, presented in fig. 5 show, that when the thermal conductivity of the supporting wall λl is increased from 0.1 w/(m∙k) till 1 w/(m∙k), value of the point thermal transmittance is increased from χ = 0.008 w/k till χ = 0.039 w/k (it’s almost 5 times higher), the supplement of the heat transmittance coefficient δu is increased from 0.022 till 0.109 w/(m2∙k), because of the influence of the fixing elements. fig. 5. dependence of the calculated value of the thermal bridge of the fixing element on the value of the point thermal transmittance of the supporting wall fig.6 normal p-p plot of regression standardized residual, with different value of the point thermal transmittance of the supporting wall material 1 2 1 2 1 2 fig. 5 dependence of the calculated value of the thermal bridge of the fixing element on the value of the point thermal transmittance of the supporting wall a b c fig. 4. thermal flow with different thermal conductivity of the layer of the supporting wall: a) λl = 0.1 w/ m∙k; b) λl = 0.5 w/ m∙k; c) λl = 1 w/ m∙k; 1 – supporting wall; 2 – thermal insulation layer. the obtained results show, that the fixing elements of the buildings with ventilated facade systems are going through the insulation layer and they have higher thermal conductivity compared with insulation layer. that’s why there were high thermal flows in the intersection part and the effectiveness of thermal transmittance was increased. the point thermal transmittance (χ-value) depends on the type and material of the fixing element, as well as on the properties of the other construction materials: on the thermal conductivity and thickness of the insulation layer as well as on the thermal conductivity and thickness of the supporting wall. 3.2 evaluation of the dependency of thermal bridge fig. 5 presents dependence of the point thermal transmittance (χ-value) of the fixing element from the thermal conductivity of the supporting wall (1st var., table 1). if the thermal conductivity value λl of the supporting wall is increased, the influence of the point thermal transmittance (χ-value) to the total envelope’s heat transmittance is increased by logarithmic distribution. results, presented in fig. 5 show, that when the thermal conductivity of the supporting wall λl is increased from 0.1 w/(m∙k) till 1 w/(m∙k), value of the point thermal transmittance is increased from χ = 0.008 w/k till χ = 0.039 w/k (it’s almost 5 times higher), the supplement of the heat transmittance coefficient δu is increased from 0.022 till 0.109 w/(m2∙k), because of the influence of the fixing elements. fig. 5. dependence of the calculated value of the thermal bridge of the fixing element on the value of the point thermal transmittance of the supporting wall fig.6 normal p-p plot of regression standardized residual, with different value of the point thermal transmittance of the supporting wall material ity value λ l of the supporting wall is increased, the influence of the point thermal transmittance (χ-value) to the total envelope’s heat transmittance is increased by logarithmic distribution. results, presented in fig. 5 show, that when the thermal conductivity of the supporting wall λ l is increased from 0.1 w/(m∙k) till 1 w/(m∙k), value of the point thermal transmittance is increased from χ = 0.008 w/k till χ = 0.039 w/k (it’s almost 5 times higher), the supplement of the heat transmittance coefficient δu is increased from 0.022 till 0.109 w/(m2∙k), because of the influence of the fixing elements. if eq. 7 is transformed as: (7) (8) χ = β0 +β1 ln∙λl ln λt = a logarithmic function of the point thermal transmittance (χ-value) of the supporting wall could be given as follow: 65 journal of sustainable architecture and civil engineering 2015/2/11 correlation between the value of the point thermal transmittance (χ-value) and the value of thermal conductivity coefficient of the supporting wall is strong (r = 0.997). the positive value of the correlation coeffig. 6 normal p-p plot of regression standardized residual, with different value of the point thermal transmittance of the supporting wall material we are getting expression of linear regression (9), which statistical reliability is checked later: χ = β0 +β1 a (9) χ = 0.038 +0.014∙ln∙λl (10) ficient is showed, that with the increase of the thermal conductivity coefficient of the layer of the supporting wall (λ l ) the point thermal transmittance (χ-value) was increased as well. it was not an accidental coincidence and correlation was statistically significant (the determined p–value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.994. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem a b c fig. 4. thermal flow with different thermal conductivity of the layer of the supporting wall: a) λl = 0.1 w/ m∙k; b) λl = 0.5 w/ m∙k; c) λl = 1 w/ m∙k; 1 – supporting wall; 2 – thermal insulation layer. the obtained results show, that the fixing elements of the buildings with ventilated facade systems are going through the insulation layer and they have higher thermal conductivity compared with insulation layer. that’s why there were high thermal flows in the intersection part and the effectiveness of thermal transmittance was increased. the point thermal transmittance (χ-value) depends on the type and material of the fixing element, as well as on the properties of the other construction materials: on the thermal conductivity and thickness of the insulation layer as well as on the thermal conductivity and thickness of the supporting wall. 3.2 evaluation of the dependency of thermal bridge fig. 5 presents dependence of the point thermal transmittance (χ-value) of the fixing element from the thermal conductivity of the supporting wall (1st var., table 1). if the thermal conductivity value λl of the supporting wall is increased, the influence of the point thermal transmittance (χ-value) to the total envelope’s heat transmittance is increased by logarithmic distribution. results, presented in fig. 5 show, that when the thermal conductivity of the supporting wall λl is increased from 0.1 w/(m∙k) till 1 w/(m∙k), value of the point thermal transmittance is increased from χ = 0.008 w/k till χ = 0.039 w/k (it’s almost 5 times higher), the supplement of the heat transmittance coefficient δu is increased from 0.022 till 0.109 w/(m2∙k), because of the influence of the fixing elements. fig. 5. dependence of the calculated value of the thermal bridge of the fixing element on the value of the point thermal transmittance of the supporting wall fig.6 normal p-p plot of regression standardized residual, with different value of the point thermal transmittance of the supporting wall material (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0, so there were no extremes. fig. 6 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. results presented in fig. 7 show, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance (χ-value) according to the value of the thermal conductivity coefficient of the layer of the supporting wall, empirical equation could be used (eq. 10): the thickness of the supporting wall (d l ) also had influence on the value of the point thermal transmittance (2nd var., table 1). results presented in fig. 7, show the change of the value of the point thermal transmittance, when the thickness of the construction was changed from 50 till 500 mm (2st.var. logarithmic function of the point thermal transmittance (χ-value) of the supporting wall could be given as follow: χ = β0 +β1 ln∙λl (7) if eq. 7 is transformed as: ln λt = a (8) we are getting expression of linear regression (9), which statistical reliability is checked later: χ = β0 +β1 a (9) correlation between the value of the point thermal transmittance (χ-value) and the value of thermal conductivity coefficient of the supporting wall is strong (r = 0.997). the positive value of the correlation coefficient is showed, that with the increase of the thermal conductivity coefficient of the layer of the supporting wall (λl) the point thermal transmittance (χvalue) was increased as well. it was not an accidental coincidence and correlation was statistically significant (the determined p–value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.994. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0, so there were no extremes. fig. 6 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. results presented in fig. 7 show, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance (χ-value) according to the value of the thermal conductivity coefficient of the layer of the supporting wall, empirical equation could be used (eq. 10): χ = 0.038 +0.014∙ln∙λl (10) the thickness of the supporting wall (dl) also had influence on the value of the point thermal transmittance (2nd var., table 1). results presented in fig. 7, show the change of the value of the point thermal transmittance, when the thickness of the construction was changed from 50 till 500 mm (2st.var. table 1). it was determined that when the thickness of the supporting wall was increased, the value of the point thermal transmittance was decreasing (from χ = 0.034 w/k till χ = 0.022 w/k). respectively, the additive of the heat transmittance coefficient because of the influence of the fixing elements (δu = χ ∙ n) decreased from 0.094 till 0.060 w/(m2∙k). fig.7. the dependence of the calculated values of the point thermal transmittance on the thickness of the supporting wall fig.8. normal p-p plot of regression standardized residual, with different value of supporting wall thickness correlation between the value the point thermal transmittance (χ-value) and value of the thickness of the supporting wall (dt) was strong (r = -0.988). a negative value of the correlation coefficient r indicated that with the increase of the table 1). it was determined that when the thickness of the supporting wall was increased, the value of the point thermal transmittance was decreasing (from χ = 0.034 w/k till χ = 0.022 w/k). respectively, the additive of the heat transmittance coefficient because of the influence of the fixing elements (δu = χ ∙ n) decreased from 0.094 till 0.060 w/(m2∙k). correlation between the value the point thermal transmittance (χ-value) and value of the thickness of the supporting wall (d t ) was strong (r = -0.988). a negative value of the fig. 7 the dependence of the calculated values of the point thermal transmittance on the thickness of the supporting wall journal of sustainable architecture and civil engineering 2015/2/11 66 correlation coefficient r indicated that with the increase of the value of thickness of the supporting wall, the value of the point thermal transmittance (χ-value) was decreasing. it was not an accidental coincidence and correlation was statistically significant (the determined p–value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.977. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0, so there were no extremes. fig. 8 normal p-p plot of regression standardized residual, with different value of supporting wall thickne logarithmic function of the point thermal transmittance (χ-value) of the supporting wall could be given as follow: χ = β0 +β1 ln∙λl (7) if eq. 7 is transformed as: ln λt = a (8) we are getting expression of linear regression (9), which statistical reliability is checked later: χ = β0 +β1 a (9) correlation between the value of the point thermal transmittance (χ-value) and the value of thermal conductivity coefficient of the supporting wall is strong (r = 0.997). the positive value of the correlation coefficient is showed, that with the increase of the thermal conductivity coefficient of the layer of the supporting wall (λl) the point thermal transmittance (χvalue) was increased as well. it was not an accidental coincidence and correlation was statistically significant (the determined p–value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.994. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0, so there were no extremes. fig. 6 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. results presented in fig. 7 show, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance (χ-value) according to the value of the thermal conductivity coefficient of the layer of the supporting wall, empirical equation could be used (eq. 10): χ = 0.038 +0.014∙ln∙λl (10) the thickness of the supporting wall (dl) also had influence on the value of the point thermal transmittance (2nd var., table 1). results presented in fig. 7, show the change of the value of the point thermal transmittance, when the thickness of the construction was changed from 50 till 500 mm (2st.var. table 1). it was determined that when the thickness of the supporting wall was increased, the value of the point thermal transmittance was decreasing (from χ = 0.034 w/k till χ = 0.022 w/k). respectively, the additive of the heat transmittance coefficient because of the influence of the fixing elements (δu = χ ∙ n) decreased from 0.094 till 0.060 w/(m2∙k). fig.7. the dependence of the calculated values of the point thermal transmittance on the thickness of the supporting wall fig.8. normal p-p plot of regression standardized residual, with different value of supporting wall thickness correlation between the value the point thermal transmittance (χ-value) and value of the thickness of the supporting wall (dt) was strong (r = -0.988). a negative value of the correlation coefficient r indicated that with the increase of the results of p-p graphic presented in fig. 8 show, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance (χ-value) according to the value of the thickness of the supporting wall (d t ), empirical equation could be used (eq. 11): χ = 0.034 0.025dl (11) the values of the point thermal transmittance of the fixing elements also depend on the values of thermal conductivity of the insulation layer (λ t ). results presented in fig. 9, show the change of the value of the point thermal transmittance, when the values of thermal conductivity of the insulation layer λ t was changed from 0.03 w/(m∙k) till 0.04 w/(m∙k) (3st. var. table 1). it was determined, that when the thermal conductivity coefficient of the insulation layer (λ t ) was increased, the value of the point thermal transmittance was decreasing from 0.029 w/k till 0.028 w/k. respectively, the additive of the heat transmittance coefficient because of the influence of the fixing elements (δu = χ ∙ n) decreased from 0.081 till 0.078 w/(m2∙k). correlation between the value of the point thermal transmittance and value of thermal conductivity coefficient of the insulation layer existed (r = 0.999). a negative value of the correlation coefficient r indicated that with the increase of the value of thermal conductivity coefficient of the insulation layer, the value of the point thermal transmittance was decreasing. it was not an fig. 9 the dependence of the calculated values of the point thermal transmittance on the values of thermal conductivity of the insulation layer value of thickness of the supporting wall, the value of the point thermal transmittance (χ-value) was decreasing. it was not an accidental coincidence and correlation was statistically significant (the determined p–value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.977. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0, so there were no extremes. results of p-p graphic presented in fig. 8 show, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance (χ-value) according to the value of the thickness of the supporting wall (dt), empirical equation could be used (eq. 11): χ = 0.034 0.025dl (11) the values of the point thermal transmittance of the fixing elements also depend on the values of thermal conductivity of the insulation layer (λt). results presented in fig. 9, show the change of the value of the point thermal transmittance, when the values of thermal conductivity of the insulation layer λt was changed from 0.03 w/(m∙k) till 0.04 w/(m∙k) (3st. var. table 1). it was determined, that when the thermal conductivity coefficient of the insulation layer (λt) was increased, the value of the point thermal transmittance was decreasing from 0.029 w/k till 0.028 w/k. respectively, the additive of the heat transmittance coefficient because of the influence of the fixing elements (δu = χ ∙ n) decreased from 0.081 till 0.078 w/(m2∙k). fig.9. the dependence of the calculated values of the point thermal transmittance on the values of thermal conductivity of the insulation layer fig.10 normal p-p plot of regression standardized residual, with different value of thermal conductivity of the insulation layer correlation between the value of the point thermal transmittance and value of thermal conductivity coefficient of the insulation layer existed (r = 0.999). a negative value of the correlation coefficient r indicated that with the increase of the value of thermal conductivity coefficient of the insulation layer, the value of the point thermal transmittance was decreasing. it was not an accidental coincidence and correlation was statistically significant (the determined p–value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.999. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. therefore, in order to detect value of the point thermal transmittance according to the value of thermal conductivity of the insulation layer, empirical equation could be used (eq. 12): χ = 0.032 0.093λt (12) fig. 10 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. accidental coincidence and correlation was statistically significant (the determined p– value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.999. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. therefore, in order to detect value of the point thermal transmittance according to the value of thermal conductivity of the insulation layer, empirical equation could be used (eq. 12): 67 journal of sustainable architecture and civil engineering 2015/2/11 fig. 10 normal p-p plot of regression standardized residual, with different value of thermal conductivity of the insulation layer χ = 0.032 0.093λt (12) fig. 10 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. results presented in fig. 11, show the change of the value of the point thermal transmittance, when the thickness of the insulation layer d t was changed from 100 mm till 200 mm (4 var. of the calculation, table 1). it was determined, that when the thickness of the insulation layer was increased till 150 mm, the value of the point thermal transmittance was increasing. later this tendency of increase is not so strong. when the thickness of the insulation layer was increased till 180 mm, the value of the point thermal transmittance χ was reaching 0.02935 w/k. respectively, the additive of the heat transmittance coefficient δu because of the influence of the fixing elements was increasing up to 0.082 w/ (m2∙k). that showed, that the value of the point thermal transmittance dependence was not linear. therefore, the curve presented in the fig. 11 could be described by following dependence (13): value of thickness of the supporting wall, the value of the point thermal transmittance (χ-value) was decreasing. it was not an accidental coincidence and correlation was statistically significant (the determined p–value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.977. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0, so there were no extremes. results of p-p graphic presented in fig. 8 show, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance (χ-value) according to the value of the thickness of the supporting wall (dt), empirical equation could be used (eq. 11): χ = 0.034 0.025dl (11) the values of the point thermal transmittance of the fixing elements also depend on the values of thermal conductivity of the insulation layer (λt). results presented in fig. 9, show the change of the value of the point thermal transmittance, when the values of thermal conductivity of the insulation layer λt was changed from 0.03 w/(m∙k) till 0.04 w/(m∙k) (3st. var. table 1). it was determined, that when the thermal conductivity coefficient of the insulation layer (λt) was increased, the value of the point thermal transmittance was decreasing from 0.029 w/k till 0.028 w/k. respectively, the additive of the heat transmittance coefficient because of the influence of the fixing elements (δu = χ ∙ n) decreased from 0.081 till 0.078 w/(m2∙k). fig.9. the dependence of the calculated values of the point thermal transmittance on the values of thermal conductivity of the insulation layer fig.10 normal p-p plot of regression standardized residual, with different value of thermal conductivity of the insulation layer correlation between the value of the point thermal transmittance and value of thermal conductivity coefficient of the insulation layer existed (r = 0.999). a negative value of the correlation coefficient r indicated that with the increase of the value of thermal conductivity coefficient of the insulation layer, the value of the point thermal transmittance was decreasing. it was not an accidental coincidence and correlation was statistically significant (the determined p–value = 0 < 0.05). with the use of linear regression method, determination coefficient was r2 = 0.999. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. therefore, in order to detect value of the point thermal transmittance according to the value of thermal conductivity of the insulation layer, empirical equation could be used (eq. 12): χ = 0.032 0.093λt (12) fig. 10 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. results presented in fig. 11, show the change of the value of the point thermal transmittance, when the thickness of the insulation layer dt was changed from 100 mm till 200 mm (4 var. of the calculation, table 1). it was determined, that when the thickness of the insulation layer was increased till 150 mm, the value of the point thermal transmittance was increasing. later this tendency of increase is not so strong. when the thickness of the insulation layer was increased till 180 mm, the value of the point thermal transmittance χ was reaching 0.02935 w/k. respectively, the additive of the heat transmittance coefficient δu because of the influence of the fixing elements was increasing up to 0.082 w/(m2∙k). that showed, that the value of the point thermal transmittance dependence was not linear. therefore, the curve presented in the fig. 11 could be described by following dependence (13): χ = β0 +β1 ; (13) by transforming (14) this dependence we are getting linear regression expression (15), which statistical significance is tested later. (14) χ = β0 + β1∙a. (15) fig.11. the dependence of the calculated values of the point thermal transmittance on the thickness of the insulation layer fig.12 normal p-p plot of regression standardized residual, with different value of thickness of the insulation layer with the use of linear regression method, determination coefficient was r2 = 0.766. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0.01, so there were no extremes. fig. 12 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance according to the value of the thickness of the insulation layer, empirical equation could be used (eq. 16): χ = 0.027 + 0.067 (16) 4. discussion the point thermal transmittance (value-χ) calculation results are showing, that the point thermal transmittance (χ – value) depends on the thickness and thermal properties of building envelop. according to the results (fig. 13), it can be stated, that from all tested factors, the biggest influence to the value of the point thermal transmittance and to the increase of fig. 11 the dependence of the calculated values of the point thermal transmittance on the thickness of the insulation layer χ = β0 +β1 (13) (14) (15) by transforming (14) this dependence we are getting linear regression expression (15), which statistical significance is tested later. results presented in fig. 11, show the change of the value of the point thermal transmittance, when the thickness of the insulation layer dt was changed from 100 mm till 200 mm (4 var. of the calculation, table 1). it was determined, that when the thickness of the insulation layer was increased till 150 mm, the value of the point thermal transmittance was increasing. later this tendency of increase is not so strong. when the thickness of the insulation layer was increased till 180 mm, the value of the point thermal transmittance χ was reaching 0.02935 w/k. respectively, the additive of the heat transmittance coefficient δu because of the influence of the fixing elements was increasing up to 0.082 w/(m2∙k). that showed, that the value of the point thermal transmittance dependence was not linear. therefore, the curve presented in the fig. 11 could be described by following dependence (13): χ = β0 +β1 ; (13) by transforming (14) this dependence we are getting linear regression expression (15), which statistical significance is tested later. ;2 adt  (14) χ = β0 + β1∙a. (15) fig.11. the dependence of the calculated values of the point thermal transmittance on the thickness of the insulation layer fig.12 normal p-p plot of regression standardized residual, with different value of thickness of the insulation layer with the use of linear regression method, determination coefficient was r2 = 0.766. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0.01, so there were no extremes. fig. 12 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance according to the value of the thickness of the insulation layer, empirical equation could be used (eq. 16): χ = 0.027 + 0.067 (16) 4. discussion the point thermal transmittance (value-χ) calculation results are showing, that the point thermal transmittance (χ – value) depends on the thickness and thermal properties of building envelop. according to the results (fig. 13), it can be stated, that from all tested factors, the biggest influence to the value of the point thermal transmittance and to the increase of results presented in fig. 11, show the change of the value of the point thermal transmittance, when the thickness of the insulation layer dt was changed from 100 mm till 200 mm (4 var. of the calculation, table 1). it was determined, that when the thickness of the insulation layer was increased till 150 mm, the value of the point thermal transmittance was increasing. later this tendency of increase is not so strong. when the thickness of the insulation layer was increased till 180 mm, the value of the point thermal transmittance χ was reaching 0.02935 w/k. respectively, the additive of the heat transmittance coefficient δu because of the influence of the fixing elements was increasing up to 0.082 w/(m2∙k). that showed, that the value of the point thermal transmittance dependence was not linear. therefore, the curve presented in the fig. 11 could be described by following dependence (13): χ = β0 +β1 ; (13) by transforming (14) this dependence we are getting linear regression expression (15), which statistical significance is tested later. ;2 adt  (14) χ = β0 + β1∙a. (15) fig.11. the dependence of the calculated values of the point thermal transmittance on the thickness of the insulation layer fig.12 normal p-p plot of regression standardized residual, with different value of thickness of the insulation layer with the use of linear regression method, determination coefficient was r2 = 0.766. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0.01, so there were no extremes. fig. 12 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance according to the value of the thickness of the insulation layer, empirical equation could be used (eq. 16): χ = 0.027 + 0.067 (16) 4. discussion the point thermal transmittance (value-χ) calculation results are showing, that the point thermal transmittance (χ – value) depends on the thickness and thermal properties of building envelop. according to the results (fig. 13), it can be stated, that from all tested factors, the biggest influence to the value of the point thermal transmittance and to the increase of χ = β0 + β1∙a. results presented in fig. 11, show the change of the value of the point thermal transmittance, when the thickness of the insulation layer dt was changed from 100 mm till 200 mm (4 var. of the calculation, table 1). it was determined, that when the thickness of the insulation layer was increased till 150 mm, the value of the point thermal transmittance was increasing. later this tendency of increase is not so strong. when the thickness of the insulation layer was increased till 180 mm, the value of the point thermal transmittance χ was reaching 0.02935 w/k. respectively, the additive of the heat transmittance coefficient δu because of the influence of the fixing elements was increasing up to 0.082 w/(m2∙k). that showed, that the value of the point thermal transmittance dependence was not linear. therefore, the curve presented in the fig. 11 could be described by following dependence (13): χ = β0 +β1 ; (13) by transforming (14) this dependence we are getting linear regression expression (15), which statistical significance is tested later. (14) χ = β0 + β1∙a. (15) fig.11. the dependence of the calculated values of the point thermal transmittance on the thickness of the insulation layer fig.12 normal p-p plot of regression standardized residual, with different value of thickness of the insulation layer with the use of linear regression method, determination coefficient was r2 = 0.766. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0.01, so there were no extremes. fig. 12 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance according to the value of the thickness of the insulation layer, empirical equation could be used (eq. 16): χ = 0.027 + 0.067 (16) 4. discussion the point thermal transmittance (value-χ) calculation results are showing, that the point thermal transmittance (χ – value) depends on the thickness and thermal properties of building envelop. according to the results (fig. 13), it can be stated, that from all tested factors, the biggest influence to the value of the point thermal transmittance and to the increase of fig. 12 normal p-p plot of regression standardized residual, with different value of thickness of the insulation layer journal of sustainable architecture and civil engineering 2015/2/11 68 with the use of linear regression method, determination coefficient was r2 = 0.766. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0.01, so there were no extremes. fig. 12 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance according to the value of the thickness of the insulation layer, empirical equation could be used (eq. 16): χ = 0.027 + 0.067 (16) results presented in fig. 11, show the change of the value of the point thermal transmittance, when the thickness of the insulation layer dt was changed from 100 mm till 200 mm (4 var. of the calculation, table 1). it was determined, that when the thickness of the insulation layer was increased till 150 mm, the value of the point thermal transmittance was increasing. later this tendency of increase is not so strong. when the thickness of the insulation layer was increased till 180 mm, the value of the point thermal transmittance χ was reaching 0.02935 w/k. respectively, the additive of the heat transmittance coefficient δu because of the influence of the fixing elements was increasing up to 0.082 w/(m2∙k). that showed, that the value of the point thermal transmittance dependence was not linear. therefore, the curve presented in the fig. 11 could be described by following dependence (13): χ = β0 +β1 ; (13) by transforming (14) this dependence we are getting linear regression expression (15), which statistical significance is tested later. ;2 adt  (14) χ = β0 + β1∙a. (15) fig.11. the dependence of the calculated values of the point thermal transmittance on the thickness of the insulation layer fig.12 normal p-p plot of regression standardized residual, with different value of thickness of the insulation layer with the use of linear regression method, determination coefficient was r2 = 0.766. relevance of the selected method was approved by anova (p-value = 0). the tested multicolinearity problem (vif = 1 and it is less than 4) showed, that the problem was not present in the applicable model. cook’s maximum was 0.01, so there were no extremes. fig. 12 is presenting p-p graphic, which shows results of the relative percentage frequency of the standardized residual errors and the normal random variable. according to these results it can be stated, that normality requirement were satisfied for the standardized residual errors. therefore, in order to detect value of the point thermal transmittance according to the value of the thickness of the insulation layer, empirical equation could be used (eq. 16): χ = 0.027 + 0.067 (16) 4. discussion the point thermal transmittance (value-χ) calculation results are showing, that the point thermal transmittance (χ – value) depends on the thickness and thermal properties of building envelop. according to the results (fig. 13), it can be stated, that from all tested factors, the biggest influence to the value of the point thermal transmittance and to the increase of the point thermal transmittance (value-χ) calculation results are showing, that the point thermal transmittance (χ – value) depends on the thickness and thermal properties of building envelop. according to the results (fig. 13), it can be stated, that from all tested factors, the biggest influence to the value of the point thermal transmittance and to the increase of the heat transmittance coefficient of all construction could have thermal conductivity of the layer of the supporting wall (envelope’s u value may increase up to 35%). this factor is very important in the practice. material of the supporting wall can be different, from the masonry with good thermal properties to the monolithic concrete, which has poor thermal conductivity properties. in particular, it is important to properly evaluate houses, which are additionally insulated and construction of the wall may be not completely clear. it is also very important to select properly the material between the aluminum fixing element and construction material (interim, sheath), which can significantly reduce the flow of heat between the aluminum elements and dense, heat-conductive material of the supporting structure. when designing energy efficient buildings, where thermal insulation material thickness must be large in order to fulfill air tightness requirements set for these buildings, it is important to know that with the increase of the thickness of the thermal insulation layer, the influence of the point thermal transmittance (value-χ) to the total heat transmittance coefficient is increasing up to certain limit. then the influence of the thermal properties of thermal insulation layer on the value of the point thermal transmittance is analyzed, it can be observed, that with the increase of the effectiveness of the thermal insulation layer, the value of the point thermal transmittance is increasing. this tendency is due to the high difference of the thermal conductivity coefficient values of thermal insulation material and aluminum fixing element. the higher thermal conductivity of the material, located on one or another part of the insulation layer, will increase the value of the point thermal transmittance because of the better conditions for the heat flow to collect (inner part) or spread (external part). however, the use of the effective insulation materials in envelop will reduce heat loss more significantly than increase because of the increased the point thermal transmittance (value-χ). therefore, the values of the point thermal transmittance might be higher if polymer material with “solid, nonelastic structures” are used in ventilated systems. an important fact is that, the aluminum elements are among the most conductive materials, so the use of fixing elements made from other materials (steel, fiberglass) material will significantly decrease their influence on envelop’s thermal conductivity. when the analyses of the average values of selected factors were made, it can be observed (fig. 13), that all factors analyzed in this work are significant, so they should be assessed holistically. discussion 69 journal of sustainable architecture and civil engineering 2015/2/11 when the dependence of the point thermal bridges is made because of different parameters of the construction (thickness and thermal properties of the materials), it is possible to predict values of the point thermal transmittance if we know the value calculated for the basic design variant and differences of the construction from the basic one. it is important for the design of energy efficient performance buildings, fig. 13 increase of envelope’s u value because of the influence of different factors the heat transmittance coefficient of all construction could have thermal conductivity of the layer of the supporting wall (envelope’s u value may increase up to 35%). this factor is very important in the practice. material of the supporting wall can be different, from the masonry with good thermal properties to the monolithic concrete, which has poor thermal conductivity properties. in particular, it is important to properly evaluate houses, which are additionally insulated and construction of the wall may be not completely clear. it is also very important to select properly the material between the aluminum fixing element and construction material (interim, sheath), which can significantly reduce the flow of heat between the aluminum elements and dense, heat-conductive material of the supporting structure. when designing energy efficient buildings, where thermal insulation material thickness must be large in order to fulfill air tightness requirements set for these buildings, it is important to know that with the increase of the thickness of the thermal insulation layer, the influence of the point thermal transmittance (value-χ) to the total heat transmittance coefficient is increasing up to certain limit. then the influence of the thermal properties of thermal insulation layer on the value of the point thermal transmittance is analyzed, it can be observed, that with the increase of the effectiveness of the thermal insulation layer, the value of the point thermal transmittance is increasing. this tendency is due to the high difference of the thermal conductivity coefficient values of thermal insulation material and aluminum fixing element. the higher thermal conductivity of the material, located on one or another part of the insulation layer, will increase the value of the point thermal transmittance because of the better conditions for the heat flow to collect (inner part) or spread (external part). however, the use of the effective insulation materials in envelop will reduce heat loss more significantly than increase because of the increased the point thermal transmittance (value-χ). therefore, the values of the point thermal transmittance might be higher if polymer material with “solid, nonelastic structures” are used in ventilated systems. an important fact is that, the aluminum elements are among the most conductive materials, so the use of fixing elements made from other materials (steel, fiberglass) material will significantly decrease their influence on envelop’s thermal conductivity. when the analyses of the average values of selected factors were made, it can be observed (fig. 13), that all factors analyzed in this work are significant, so they should be assessed holistically. fig. 13. increase of envelope’s u value because of the influence of different factors when the dependence of the point thermal bridges is made because of different parameters of the construction (thickness and thermal properties of the materials), it is possible to predict values of the point thermal transmittance if we know the value calculated for the basic design variant and differences of the construction from the basic one. it is important for the design of energy efficient performance buildings, because the calculation of the point thermal transmittance (value-χ) is complicated, requiring additional knowledge, special software and the skills to use them. for these reasons, the point thermal bridges are quite often ignored in the practice. this might lead to large errors in assessing the energy efficiency of buildings and the design of heating and ventilation systems. conclusions studies have shown, that the value of the point thermal transmittance, which depended on the thermal properties of the envelop and thickness of the layers (to which aluminum fixing element is fifed), might increase to 35%. the higher thickness of the supporting wall and coefficient of thermal conductivity of insulation layer, the lower the value of the point thermal transmittance. meanwhile, the dependence of the point thermal transmittance on the thickness of insulation layer and thermal conductivity coefficient of the supporting wall was not linear. when the dependence of the values of the point thermal transmittance from the facade system components (thermal properties and thickness of the supporting wall material; type and material of the fixing element; properties and dimensions of thermal insulation material) is determined, the values of the point thermal transmittance of the selected construction design might be find by simplified calculations according to existing dependencies formulas or graphics. because the calculation of the point thermal transmittance (value-χ) is complicated, requiring additional knowledge, special software and the skills to use them. for these reasons, the point thermal bridges are quite often ignored in the practice. this might lead to large errors in assessing the energy efficiency of buildings and the design of heating and ventilation systems. studies have shown, that the value of the point thermal transmittance, which depended on the thermal properties of the envelop and thickness of the layers (to which aluminum fixing element is fifed), might increase to 35%. the higher thickness of the supporting wall and coefficient of thermal conductivity of insulation layer, the lower the value of the point thermal transmittance. meanwhile, the dependence of the point thermal transmittance on the thickness of insulation layer and thermal conductivity coefficient of the supporting wall was not linear. when the dependence of the values of the point thermal transmittance from the facade system components (thermal properties and thickness of the supporting wall material; type and material of the fixing element; properties and dimensions of thermal insulation material) is determined, the values of the point thermal transmittance of the selected construction design might be find by simplified calculations according to existing dependencies formulas or graphics. the dependence of the point thermal bridge established in this work, requires more detailed assessment of these bridges. it should not be limited to typical schemes, which often ignore the precise thickness and characteristics of the material. conclusions referencesascione f., bianco n., de masi, r.f., mauro, g.m., musto, m., vanoli g.p. experimental validation of a numerical code by thin film heat flux sensors for the resolution of thermal bridges in dynamic conditions. applied energy, 2014; 124:213-222. http://dx.doi.org/10.1016/j.apenergy.2014.03.014 ascione f., bianco n., de rossi f., turni g., vanoli g.p. different methods for the modeling of thermal bridges into energy simulation programs: comparisons of accuracy for flat heterogeneous roofs in 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paper. 2008. de andelis, e., serra, e. light steel-frame walls: thermal insulation performances and thermal bridges. energy procardia, 2014; 45:362-371. http:// dx.doi.org/10.1016/j.egypro.2014.01.039 en iso 14683:2008 thermal bridges in building construction – linear thermal transmittance – simplified methods and default values. en ios 10211:2008 thermal bridges in building construction – heat flows and surface temperatures – detailed calculations. evola, g., margani, g., marletta, l. energy and cost evaluation of thermal bridge correction in mediterranean climate, energy and buildings, 2011; 43:2385-2393. http://dx.doi.org/10.1016/j. enbuild.2011.05.028 european commission. directive 2010/31/eu of the european parliament and of the council of 19 th may 2010 on the energy performance of buildings, available from internet:http://eur-lex.europa.eu/ legal-content/en/all/?uri=celex:32010l0031. ge, h., mcclung, v.r., zhang, s. impact of balcony thermal bridges on the overall thermal performance of multi-unit residential buildings: a case study, energy and buildings, 2013; 60:163-173. http:// dx.doi.org/10.1016/j.enbuild.2013.01.004 gao, y., roux, j.j., zhao, l.h., jiang, y. dinamical building simulation: a low order model for thermal bridges losses, energy and buildings, 2008; 40:2236-2243. http://dx.doi.org/10.1016/j. enbuild.2008.07.003 gomes, a.p., de souza, h.a., tribess, a. impact of thermal bridging on the performance of building using light steel framing in brazil. applied thermal engineering, 2013; 52:84-89. http://dx.doi. org/10.1016/j.applthermaleng.2012.11.015 martin, k., escudero, c., erkoreka, a., flores, i., sala, j.m. equivalent wall method for dynamic characterization of thermal bridges, energy and building, 2012; 55:704-714. http://dx.doi. org/10.1016/j.enbuild.2012.08.024 martin, k., erkoreka, a., flores, i., odriozola, m., sala, j.m. problems in the calculation of thermal bridges in dynamic conditions. energy and buildings, 2011; 43:529-535. http://dx.doi. org/10.1016/j.enbuild.2010.10.018 petranek, v., subrit, r., plachy, j., nevrivova, l., petricek, t., kalousek, l., caha, z. thermal bridgrs in insulation system. thermal, power and electrical engineering, pts. 1 and 2., 2013; 732-733:182-185. str 2.05.01:2013. pastatų energinio naudingumo projektavimas [energy performance of buildings design]. vilnius, ministry of environment of republic of lithuania, 2005. tadeu, a., simoes, i., simoes, n., prata, j. simulation of dynamic liner thermal bridges using a boundary element method model in the frequency domain, energy and building, 2011; 43:3685-3695. http://dx.doi.org/10.1016/j. enbuild.2011.10.001 theodosiou, t.,g., papadopoulos, a., m. the impact of thermal bridges on the energy demand of buildings with double brick wall constructions. energy and buildings, 2008; 40:2083-2089. http:// dx.doi.org/10.1016/j.enbuild.2008.06.006 theodosiou, t., tsikaloudaki, k., bikas, d., aravantinos, d., kontoleon, k.n. assessing the use of simplilied and analytical methods for approaching thermal bridges with regard to their impact on the thermal performance of the building envelope. world sb 14 conference on the sustainable building: result, 2014, october 28-30th, barcelona, span. available from internet: http://wsb14barcelona.org/programme/pdf_ poster/p-059.pdf qasass, r., gorgolewski, m., ge, h. timber framing factor in toronto residential house construction. architectural science review, 2014; 57(3):159-168. http://dx.doi.org/10.1080/000386 28.2013.869193 71 journal of sustainable architecture and civil engineering 2015/2/11 jolanta šadauskienė assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area energy efficiency of buildings, heat transfer and thermal insulation, building envelope humidity behavior address studentu st. 48, lt44403, kaunas, lithuania tel. +370 37 350453 e-mail: jolanta.sadauskiene@ ktu.lt about the authors juozas ramanauskas researcher laboratory of building physics at the institute of architecture and construction, ktu assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building materials main research area energy efficiency of buildings, heat transfer and thermal insulation, building envelope humidity behaviour address tunelio st. 60, lt-44405, kaunas, lithuania tel. +370 37 350779 e-mail: juozas.ramanauskas@ ktu.lt lina šeduikytė assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area microclimate of buildings, live cycle of buildings, energy efficiency of buildings address studentu st. 48, lt44403, kaunas, lithuania tel. +370 37 350453 e-mail: lina.seduikyte@ktu.lt andrius buska dr. technical manager company „rockwool“ main research area thermal properties of materials, heat transfer and thermal insulation address a. goštauto st. 40b, lt-01112 vilnius, lithuania tel. +370 5 2126024 e-mail: andrius.buska@ rockwool.com 57 journal of sustainable architecture and civil engineering 2017/2/19 *corresponding author: viktoras.dorosevas@ktu.lt investigation of sand behaviour under cyclic loading received 2016/12/08 accepted after revision 2017/05/03 investigation of sand behaviour under cyclic loading jsace 2/19 http://dx.doi.org/10.5755/j01.sace.19.2.17223 siddeshwaran parthiban, gediminas stelmokaitis, viktoras doroševas* kaunas university of technology, faculty of civil engineering and architecture studentu str. 48, lt-51367 kaunas, lithuania journal of sustainable architecture and civil engineering vol. 2 / no. 19 / 2017 pp. 57-64 doi 10.5755/j01.sace.19.2.17223 © kaunas university of technology introduction one of the challenges in geotechnical engineering is how to evaluate sandy soil behaviour under cycling loading. this challenge has led to several research projects regarding cyclic loading. however, due to the complexity of the loading and the effects hereof, no standardized method for taking into consideration the cyclic loading has been made yet. therefore, the topic of cyclic loading still needs more investigation. proposed study finds an alternative approach to determine quantifiable methods for determination of cyclic load parameters like compressibility and shear modulus of sand, secant modulus, damping coefficients for various applied frequencies and account for shear strength of sands in worst case scenarios. it is also proposed the method, how to determine liquefaction potential and critical void ratios for various reconstituted sand mixtures in a laboratory setting. the purpose of investigation is to describe how the sandy soil behaves when it is subjected to cyclic loading. cyclic loading can be caused by environmental loads by wind, transport systems, earthquakes and even human induced loads like explosions. this form of loading will have influence on soil properties such as soil stiffness, shear strength, and void ratio. two different well graded sands are characterized and studied under static and dynamic loading and settlement studies are also performed on model footing being loaded on these sand samples. frequency response of sands are also studied using shaking table subjected to frequency range of 10 – 50 hz and determined its influence on strength parameters of soil. keywords: sand, soil, behaviour, cyclic load, compressibility, settlement, strength. sand is a granular material in nature and applied load is being transmitted in sand via grain to grain contacts. the cyclic stress–strain behaviour of sand therefore depends on the physiochemical and geomorphological characteristics of the grain contacts prior and during the cyclic shearing, and on the magnitude and direction of the contact forces. microscopic aspects of the sand structure and its behaviour depends on the properties of grain contacts and their changes due to the external loading is a complex subject which is summarized to different extents in a number of geotechnical textbooks. among them are books, for example (mitchell, soga, 2005), where the subject is described systematically and in considerable depth. based on the synthesis of relevant studies, also including the pioneering work of terzaghi, it was offered the description of sand microstructure that can be summarized as follows. the surface of sand grains is rough, with successions of nanoscale asperities and depressions. when the surfaces of adjacent grains are brought together by force, their contact is established through these asperities, which are subjected to very high stresses. the compressed asperities form the actual solid-to-solid contacts, which cumujournal of sustainable architecture and civil engineering 2017/2/19 58 lative area is just a small fraction of the total grain-to-grain contact surface. due to the extreme stresses, the mineral material at and around the solid-to-solid contacts yields and undergoes plastic deformation which results in the chemical bond formation at the points of contacts. the cohesive forces at such plastic junctions are the source of sand shear stiffness and frictional resistance, which magnitudes depend on the molecular structure and composition of contacting asperities. in addition to that, the grain surfaces are covered with a thin layer of adsorbed material from adjacent phases (water and/or air in the voids), but under high pressure the grain mineral at asperities penetrates through this film and forms the mineral solid-to-solid contacts. it is easy to comprehend that in such a sand structure, even at very small cyclic strains, the cyclic deformations and rubbing at and around the solid-to-solid contacts must modify the properties of the contacts in some manner, and that such changes must change the stiffness and elasticity moduli of the sand. in fact, this phenomenon has been recognized before by drnevich and richart in one of their studies on the cyclic behaviour of sand under small cyclic strains. evaluation of liquefaction resistance and earthquake-induced pore water pressure (pwp) in sands are a topic of considerable importance among the geotechnical engineers. numerous researchers have investigated liquefaction potential of sand through the experimental (di prisco et al., 2000), numerical (dafalias, manzari, 2004) and empirical approaches (modoni et al., 2011). experimental investigations have constituted the basis of liquefaction studies and provided considerable insight into this problematic undrained behaviour of soils. the sand soil is the object of research in this paper. two sand samples a and b which has a particle grading of well graded (gw) are used and the particle size distribution is being plotted to differentiate various fractions of sand particle. these sands are subjected to static and cyclic loading. settlement studies are performed on purpose to analyse the failure modes in dry state and saturated state. particle size distribution the sands were characterised according to eurocode 7 and subjected to all index properties and particle size distribution. the sand samples were free of any organic matter and had very small amount of fine content, less than 2% by mass. the sands grading results are shown in fig. 1 and characteristics of the sand are given in table 1. methods table1 index properties of sand samples sand a sand b 1. specific gravity – 2.62 specific gravity – 2.58 2. coefficient of uniformity cu 6 coefficient of uniformity cu 6 3. coefficient of curvature cc 2.4 coefficient of curvature cc 2.1 fig. 1 particle size distribution 59 journal of sustainable architecture and civil engineering 2017/2/19 the sands are classified as well graded sand-gw. simple shear tests under statical and dynamic loads the mechanical properties of the soil are the most important ones for geotechnical engineers. laboratory tests have been performed in order to determine the shear stress of failure, as well as its cohesion (c) and angle of friction (φ). the tests were performed under static conditions and by inducing vibrations on sand sample on purpose to determine the change of mechanical properties of sand affected by vibrations. the failure shear stress of sand with and without vibrations have been found using field laboratory apparatus pll-9. vibrations in soil can be generated from various sources, i.e. road traffic, pile driving, explosions and construction equipment. these sources generate waves with frequency up to 70 hz. the fig. 2 static and dynamic testing 0 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 p er ce nt ag e fin er b y w ei gh t, % particle size (mm) specimens of sand used in this testing were cylindrical shape of 56.5 mm diameter and 20 mm height. shear tests on sand have been performed with three different normal stresses: 100 kpa, 200 kpa and 300 kpa and placing the apparatus on laboratory shaking table that induces vibrations of 50 hz frequency (fig. 2). horizontal load was increased with a step of 4.8 kpa of shear stress on sand specimen until it reached limit state and failure shear stress. as it is known, the shear strength of soil can be expressed by coulomb equation: where: tanf c    – failure shear stress; c – cohesion; σ – normal stress; φ – internal angle of friction. (1)tanf c    shear tests on sands have been carried out under static conditions and with vibrations of 50 hz frequency. tests with 50 hz vibrations were performed on laboratory shaking table (fig. 2) and the sands were tested in dry state until failure. settlement studies the sands were tested using a model footing on purpose to investigate the settlement in static conditions and loaded until general shear failure is obtained (fig. 3). fig. 3 the settlement testing model journal of sustainable architecture and civil engineering 2017/2/19 60 these studies were done to validate the scaling effect and check in which extent the experimental results correspond to analytical solution. based on the theory of elasticity, the elastic settlement si of a flexible footing, either rectangular of dimensions l × b (l > b) or circular of diameter b, is given by where: is – influence factor depending on the shape and l/b ratio; (for case a and b is = 0.85); q – uniform loading; e – modulus of elasticity; μ – poisson’s ratio. (2)  21 s qb s i e   (3) for average settlement: friction angle tests friction angle tests on sand have been carried out with uvt-2 and uo (fig. 4) under vibrations with 10 hz, 20hz, 40 hz and 50 hz frequency. the vibrations were performed using frequency changing vibration table in technological systems diagnostics institute of kaunas university of technology (fig. 5). the amplitude of vibrations in all tests was set to be 0.3 mm. si = 0.926s fig. 4 uvt-2(1) and uo (2) apparatus fig. 5 vibration table with uo 4 5 1 2 the results obtained during the direct shear test on sand a and b without and with vibration are illustrated in fig. 6 and fig. 7. the experiments show that vibrations had effect on cohesion parameters of sand. cohesion of sand has decreased under vibrations of 50 hz frequency and reduced the strength of sand calculating by eq. (1), but the angle of friction remained the same. the sands were tested using a model footing to investigate the settlement in static conditions. these studies were done to validate the scaling effect and check in which extent the experimental results correspond to analytical solution by eqns. (2) and (3). the results obtained during the settlement test on sand a and b are illustrated in fig. 8 and fig. 9. the experiments show that it is possible to use obtained empirical equations to calculate the average settlement under uniform load: results and discussion (4)si = aiq where: ai – uniform load coefficient, m2 n mm. 61 journal of sustainable architecture and civil engineering 2017/2/19 fig. 6 direct shear test on sand a fig. 7 direct shear test on sand b 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00 0 50 100 150 200 250 300 350 fa ilu re s he ar s tr es s, k pa normal stress, kpa without vibrations with 50 hz vibrations 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 0 50 100 150 200 250 300 350 fa ilu re s he ar s tr es s, k pa normal stress, kpa without vibrations with 50 hz vibrations 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 0 50 100 150 200 250 300 350 fa ilu re s he ar s tr es s, k pa normal stress, kpa without vibrations with 50 hz vibrations sa = 0,0346q r² = 0,894 0 1 2 3 4 5 6 7 0 20 40 60 80 100 120 140 160 180 200 se tt le m en t ( m m ) uniform load (n/m2 sb = 0,0387q r² = 0,9066 0 1 2 3 4 5 6 7 8 9 10 0 20 40 60 80 100 120 140 160 180 200 se tt le m en t ( m m ) uniform load (n/m2 ) ) fig. 8 settlement test sand a journal of sustainable architecture and civil engineering 2017/2/19 62 fig. 9 settlement test sand b the uniform load coefficient depends on sand type, for example, sand a aa = 0.0346 m2 n mm and sand b ab = 0.0387 m2 n mm. the results calculated by eq. (4) were compared to analytical solution which is defined by eqns. (2) (3) and are illustrated in fig. 10 and fig. 11. the sand samples exhibit a good correlation between analytical and experimental values during settlement studies due to the scaling effect and particle sphericity which has a strong effect on shear strength during dynamic loading events. the results obtained during the friction angle tests on loose sand under vibrations with 10 hz, 20hz, 40 hz and 50 hz frequency with uvt-2 and uo are illustrated in fig. 12. the experiments show that vibrations have effect on the angle of friction of sand slope. the angle of friction of slope sand has decreased under vibrations had increased from 10 to 50 hz frequency. fig. 10 comparison of experimental and analytical solution on sand a sa = 0,0346q r² = 0,894 0 1 2 3 4 5 6 7 0 20 40 60 80 100 120 140 160 180 200 se tt le m en t ( m m ) uniform load (n/m2 ) sb = 0,0387q r² = 0,9066 0 1 2 3 4 5 6 7 8 9 10 0 20 40 60 80 100 120 140 160 180 200 se tt le m en t ( m m ) uniform load (n/m2 ) 0 20 40 60 80 100 120 140 160 180 0 1 2 3 4 5 6 7 uniform load (pa) s et tle m en t ( m m ) analytical (case a) experimental (case a) 0 20 40 60 80 100 120 140 160 180 0 1 2 3 4 5 6 7 8 uniform load (pa) s et tle m en t ( m m ) analytical (case b) experimental (case b) 63 journal of sustainable architecture and civil engineering 2017/2/19 fig. 11 comparison of experimental and analytical solution on sand b fig. 12 friction angle on sand a and b 0 20 40 60 80 100 120 140 160 180 0 1 2 3 4 5 6 7 uniform load (pa) s et tle m en t ( m m ) analytical (case a) experimental (case a) 0 20 40 60 80 100 120 140 160 180 0 1 2 3 4 5 6 7 8 uniform load (pa) s et tle m en t ( m m ) analytical (case b) experimental (case b) 0 5 10 15 20 25 30 35 40 45 0 10 20 30 40 50 60 fr ic tio n a ng le frequency, hz sand a sand b experimental analysis until 50 hz of vibrations on sand showed that: _ it has negative effect on mechanical properties of sand; _ sand affected by 50 hz vibrations indicated that the strength of dense sand decreased because of decrease in the cohesion, and it is relative with the type of sand and frequency; _ it is important to take such change into account in geotechnical engineering because the decrease of strength of sand can cause unpredicted foundation settlements and other problems. experimental analysis of settlements test on sand showed that: _ analytical and experimental values of settlement follow a similar trend and using the scaling effect it can be calculated empirical. conclusions journal of sustainable architecture and civil engineering 2017/2/19 64 about the authors references the main strength parameter of sand (angle of friction) are also affected by vibrations. experiments showed that: _ the angle of friction is hugely affected by different frequency of vibrations; under 50 hz vibrations the angle of friction decreased by 47% while under low frequency vibrations (10 hz) sand the angle of friction was equal to 35⁰. the angle of friction of sand slope has decreased under vibrations increase. it is important to take such change into account in geotechnical engineering. mitchell jk, soga k. fundamentals of soil behaviour. hoboken, new jersey: john wiley & sons, inc.; 2005. p. 577. eurocode 7 – geotechnical design – part 2: ground investigation and testing, en 1997-2:2007/ac:2010. di prisco c., imposimato s., vardoulakis i. mechanical modelling of drained creep triaxial tests on loose sand, géotechnique 50(1) (2000)73-82. https://doi. org/10.1680/geot.2000.50.1.73 dafalias y., manzari m. simple plasticity sand model accounting for fabric change effects, j.eng. mech., 130(6) (2004) 622-634. https://doi.org/10.1061/ (asce)0733-9399(2004)130:6(622) modoni g., koseki j., anh dan l.q. cyclic stress strain response of compacted gravel, géotechnique 61(6) (2011) 473-485. https://doi.org/10.1680/ geot.7.00150 acknowledgment the authors would like to acknowledge the support of technological systems diagnostics institute and department of building structures of kaunas university of technology in conduct of this study. siddeshwaran parthiban master’s degree student kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area soil investigations, soilstructure interaction, structural dynamics address studentu st. 48, lt-51367, kaunas, lithuania e-mail: siddeshwaran. parthiban@ktu.edu gediminas stelmokaitis assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area soil investigations, soil mechanics, geology address studentu st. 48, lt-51367, kaunas, lithuania e-mail: gediminas.stelmokaitis@ ktu.edu viktoras doroševas professor kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area mechanical systems, dynamics, analytical and numerical methods, mathematical model, theoretical mechanics, mechanics of loose materials, soil mechanics, diagnostics, transportation systems in buildings, damage of structures and soil, identification system and material state, monitoring. analysis and synthesis of the reactions of structure to shock impact load and estimation address studentu st. 48-284, lt-51367, kaunas, lithuania e-mail: viktoras.dorosevas@ktu.lt 73 journal of sustainable architecture and civil engineering 2016/1/14 *corresponding author: knav@dtu.dk from a magnet to a heat pump received 2016/06/01 accepted after revision 2016/08/15 journal of sustainable architecture and civil engineering vol. 1 / no. 14 / 2016 pp. 73-79 doi 10.5755/j01.sace.14.1.15927 © kaunas university of technology from a magnet to a heat pump jsace 1/14 http://dx.doi.org/10.5755/j01.sace.14.1.15927 introduction kristina navickaitė*, henrique neves bez, kurt engelbrecht, christian r. h. bahl technical university of denmark, department of energy conversion and storage frederiksborgvej 399, 4000 roskilde, denmark the magnetocaloric effect (mce) is the thermal response of a magnetic material to an applied magnetic field. magnetic cooling is a promising alternative to conventional vapor compression technology in near room temperature applications and has experienced significant developments over the last five years. although further improvements are necessary before the technology can be commercialized. researchers were mainly focused on the development of materials and optimization of a flow system in order to increase the efficiency of magnetic heat pumps. the project, presented in this paper, is devoted to the improvement of heat pump and cooling technologies through simple tests of prospective regenerator designs. a brief literature review and expected results are presented in the paper. it is mainly focused on mce technologies and provides a brief introduction to the magnetic cooling as an alternative for conventional vapor compression technology. keywords: heat pump, heat transfer, magnetic refrigeration, magnetocaloric effect, test device modelling. the magnetocaloric effect (mce) was discovered by french and swiss physicists weiss and piccard (smith et al. 2012). in the mid-1920s debye and giauque proposed a method of adiabatic demagnetization to reach very low temperatures (smith et al. 2012). the discovery of magnetocaloric materials (mcm) with curie temperatures (tc) near room temperature (rt) has opened an opportunity for magnetic refrigeration (mr) to become an alternative to conventional vapor compression devices. furthermore, mr technology is environmentally friendly since it has zero vapor pressure, no ozone depletion potential (odp), no direct global warming potential (gwp), it has potential to be more compact layout since the working material is solid, and has the potential to work more silently than conventional compressors (bahl et al. 2008, barbosa et al. 2014, engelbrecht et al. 2011, eriksen et al. 2015, lei et al. 2016, smith et al. 2012). the mc cooling technique is based on the thermal response of a magnetic material when magnetized/demagnetized, such as a temperature increases when the field is increased and vice versa. the isothermal entropy change is negative upon magnetization and positive upon demagnetization, see fig. 1. this scenario is valid when an ordinary mce takes place and is analogous to the negative change in entropy associated with the isothermal compression of a gas. mr near rt is a desirable, but at the same time technically challenging idea. challenges are related to device engineering. barclay et al. (1981) patented the active magnetocaloric regenerator (amr) with its own ‘distributed refrigeration’ cycle which can provide refrigeration over a temperature span that is much larger than the adiabatic temperature change of the material. nevertheless, an efficient amr device requires a large magnetic field. rowe et al. (2006) concluded that journal of sustainable architecture and civil engineering 2016/1/14 74 the lower magnetic field might be compensated by increasing the operating frequency. however, nielsen and engelbrecht (2012) showed that in case of a long amr (200 mm) the importance of the thermal conductivity increases when a device is operated at a high frequency – the higher the operating frequency, the higher the thermal conductivity is necessary. seeking to optimize the configuration of machines, attention is mainly paid to the performance of it. there are several ways to increase the efficiency of an mr such as optimizing the flow system, optimizing the magnet assembly, improving regenerator geometry, and investigating new mcms, etc. nevertheless, the main attention of other researchers is paid on the investigation of materials such as changing their composition (kaštil et al. 2013). on the other hand, to build an mr with a high cop, an efficient heat exchanger is required. since the adiabatic temperature span in the mce (in the magnetic field up to 1.5 t) is limited to a maximum 5.8 k per one layer of mcm, conventional heat exchangers are not sufficient to be directly implemented in this application. the temperature span is required to be at least 30 k for conventional devices (kitanovski et al. 2015). this suggests considering a novel concept of heat exchanger. it has long been a goal to design a heat exchanger with a high heat transfer rate and low pressure drop, but now it turned to be crucially important for the successful implementation of novel cooling technologies. fig. 1 an mr material with randomly oriented spins is magnetized – the temperature of a material increases adiabatically (a) and then entropy decreases under isothermal conditions (b) from a magnet to a heat pump kristina navickaitė*, henrique neves bez, kurt engelbrecht, christian r. h. bahl technical university of denmark, department of energy conversion and storage, frederiksborgvej 399, 4000 roskilde, denmark *corresponding author: knav@dtu.dk the magnetocaloric effect (mce) is the thermal response of a magnetic material to an applied magnetic field. magnetic cooling is a promising alternative to conventional vapor compression technology in near room temperature applications and has experienced significant developments over the last five years. although further improvements are necessary before the technology can be commercialized. researchers were mainly focused on the development of materials and optimization of a flow system in order to increase the efficiency of magnetic heat pumps. the project, presented in this paper, is devoted to the improvement of heat pump and cooling technologies through simple tests of prospective regenerator designs. a brief literature review and expected results are presented in the paper. it is mainly focused on mce technologies and provides a brief introduction to the magnetic cooling as an alternative for conventional vapor compression technology. keywords: heat pump, heat transfer, magnetic refrigeration, magnetocaloric effect, test device modelling. introduction the magnetocaloric effect (mce) was discovered by french and swiss physicists weiss and piccard (smith et al. 2012). in the mid-1920s debye and giauque proposed a method of adiabatic demagnetization to reach very low temperatures (smith et al. 2012). the discovery of magnetocaloric materials (mcm) with curie temperatures (tc) near room temperature (rt) has opened an opportunity for magnetic refrigeration (mr) to become an alternative to conventional vapor compression devices. furthermore, mr technology is environmentally friendly since it has zero vapor pressure, no ozone depletion potential (odp), no direct global warming potential (gwp), it has potential to be more compact layout since the working material is solid, and has the potential to work more silently than conventional compressors (bahl et al. 2008, barbosa et al. 2014, engelbrecht et al. 2011, eriksen et al. 2015, lei et al. 2016, smith et al. 2012). the mc cooling technique is based on the thermal response of a magnetic material when magnetized/demagnetized, such as a temperature increases when the field is increased and vice versa. the isothermal entropy change is negative upon magnetization and positive upon demagnetization, see fig. 1. this scenario is valid when an ordinary mce takes place and fig. 1. temperature of a material increases adiabatically (a) and then entropy decreases under isothermal conditions (b). mr near rt is a desirable, but at the same time technically challenging idea. challenges are related to device engineering. barclay et al. (1981) patented the active magnetocaloric regenerator (amr) with its own ‘distributed refrigeration’ cycle which can provide refrigeration over a temperature span that is much larger than the adiabatic temperature change of the material. nevertheless, an efficient amr device requires a large magnetic field. rowe et al. (2006) concluded that the lower magnetic field might be compensated by increasing the operating frequency. however, nielsen and engelbrecht (2012) showed that in case of a long amr (200 mm) the importance of the thermal conductivity increases when a device is operated at a high frequency – the higher the operating frequency, the higher the thermal conductivity is necessary. seeking to optimize the configuration of machines, attention is mainly paid to the performance of it. there are several ways to increase the efficiency of an mr such as optimizing the flow system, optimizing the magnet assembly, improving a b discovered compositions are available in a variety of shapes and packing of new materials should be tested before applying them in larger and more complex prototypes. the properties of a series of such mcms are tested in a vertically oriented versatile device – the test machine, see fig. 2. it is designed in a way to allow the variation and control of many experimental parameters. a brief introduction to the main parts and operation of the test machine are given in this paper, more detailed description of the device and operational conditions are given in bahl et al. (2008) and engelbrecht et al. (2012). the device is built in a temperature controlled cabinet. the hot reservoir (1) is placed above the regenerator (2) and is linked to the forced convection heat exchanger (hex) (3) and the cold reservoir (4) (below the regenerator) is covered by thermal insulation (not shown). a halbach cylinder permanent magnet is used as a magnetic field source, with an average flux density in the bore of 1.03 t. the temperature of the hot end (thot) is controlled via the ambient (air inside the cabinet) temperature. during operation a regenerator is moved vertically by a stepper motor while the magnet is kept in a stationary position (see fig. 3). magnetization and demagnetization of the mcm is achieved in this way and a temperature span across the thermal reservoirs is built up. the heat transfer fluid is moved through the regenerator by mean of a displacer in the cold end. the entire device is in thermal contact with the same ambient air i.e. hot end is thermally linked to the ambient via a forced convection heat exchanger while the cold end is thermally insulated using foam tubing. methods 75 journal of sustainable architecture and civil engineering 2016/1/14 the test machine can be operated in different combinations of various parameters, such as a different piston (displacer) stroke (amplitude) and velocity. the heat transfer fluid flow is provided by pushing the piston backwards and forwards. in this manner the fluid velocity and volume of the flow can be controlled. the velocity of the fluid directly affects utilization, which represents the ratio of the thermal capacity of the fluid that moves into regenerator to the thermal capacity of the solid regenerator material. the expression to define utilization (φ) is given below: fig. 2 a photo of the test machine installed in the temperature controlled cabinet (a) and the schematic drawing (b) (engelbrecht et al. 2012) fig. 3 the test machine with the magnetic regenerator a) outside and b) inside the magnet regenerator geometry, and investigating new mcms, etc. nevertheless, the main attention of other researchers is paid on the investigation of materials such as changing their composition (kaštil et al. 2013). on the other hand, to build an mr with a high cop, an efficient heat exchanger is required. since the adiabatic temperature span in the mce (in the magnetic field up to 1.5 t) is limited to a maximum 5.8 k per one layer of mcm, conventional heat exchangers are not sufficient to be directly implemented in this application. the temperature span is required to be at least 30 k for conventional devices (kitanovski et al. 2015). this suggests considering a novel concept of heat exchanger. it has long been a goal to design a heat exchanger with a high heat transfer rate and low pressure drop, but now it turned to be crucially important for the successful implementation of novel cooling technologies. methods discovered compositions are available in a variety of shapes and packing of new materials should be tested before applying them in larger and more complex prototypes. the properties of a series of such mcms are tested in a vertically oriented versatile device – the test machine, see fig. 2. it is designed in a way to allow the variation and control of many experimental parameters. a brief introduction to the main parts and operation of the test machine are given in this paper, more detailed description of the device and operational conditions are given in bahl et al. (2008) and engelbrecht et al. (2012). the device is built in a temperature controlled cabinet. the hot reservoir (1) is placed above the regenerator (2) and is linked to the forced convection heat exchanger (hex) (3) and the cold reservoir (4) (below the regenerator) is covered by thermal insulation (not shown). a halbach cylinder permanent magnet is used as a magnetic field source, with an average flux density in the bore of 1.03 t. the temperature of the hot end (thot) is controlled via the ambient (air inside the cabinet) temperature. during operation a regenerator is moved vertically by a stepper motor while the magnet is kept in a stationary position (see fig. 3). magnetization and demagnetization of the mcm is achieved in this way and a temperature span across the thermal reservoirs is built up. the heat transfer fluid is moved through the regenerator by mean of a displacer in the cold end. the entire device is in thermal contact with the same ambient air i 1 2 4 (2) (3) a b fig. 3. the test machine with the magnetic regenerator a) outside and b) inside the magnet. the test machine can be operated in different combinations of various parameters, such as a different piston (displacer) stroke (amplitude) and velocity. the heat transfer fluid flow is provided by pushing the piston backwards and forwards. in this manner the fluid velocity and volume of the flow can be controlled. the velocity of the fluid directly affects utilization, which represents the ratio of the thermal capacity of the fluid that moves into regenerator to the thermal capacity of the solid regenerator material. the expression to define utilization () is given below: (1) where: ṁf – mass of the fluid pushed through the regenerator in one direction; cf and cs – specific heat of the fluid and the solid, respectively; ms –mass of the solid regenerator (neves bez et al. 2016). to find the optimal working point of the mcm, thot is set slightly above the tc of the working material and series of tests are run under the following conditions: 1. at different piston amplitudes, when the utilization (eq. 1) of a regenerator is known. the sample is tested at the same temperature (slightly above the tc) and piston velocity conditions. the point where the temperature span is the highest is selected to be the optimal piston amplitude for the remaining tests of the same regenerator. 2. at different piston velocities, when the optimal piston amplitude is known. the sample is tested at the same temperature (same as at the first step) and piston amplitude conditions. the point where the temperature span is at the peak is selected to be the optimal piston velocity for the remaining tests of the same regenerator. 3. at the different temperature range, when the piston amplitude and velocity is constant. when working point is known, a test against temperature change is made in order to find the peak of the temperature span of the tested sample. a) b) c) fig. 4. the mcm regenerator a) stacked plate regenerator b) top view and c) side view. geometry of the housing of the regenerators ø~38mm (outer) and h=40mm. two types of regenerators have been tested in the test machine. the parallel plate regenerator is shown in the fig. 4. a). the irregular particle regenerator is shown in fig. 4 b) and c). the mcm and their characteristics are not discussed further in this paper. more information about the both types of the regenerators might be found in bahl et al. (2016) and neves bez et al. (2016), respectively. the results for three regenerators, in the form of irregular particles (see fig. 4 b and c) are presented in this paper. all of the presented regenerators were bonded with a small amount of epoxy which is meant to maintain the mechanical integrity of the regenerator. a water based solution (2 wt%) of anti-corrosion inhibitor entek fne was used as a heat transfer liquid. fig. 3. the test machine with the magnetic regenerator a) outside and b) inside the magnet. the test machine can be operated in different combinations of various parameters, such as a different piston (displacer) stroke (amplitude) and velocity. the heat transfer fluid flow is provided by pushing the piston backwards and forwards. in this manner the fluid velocity and volume of the flow can be controlled. the velocity of the fluid directly affects utilization, which represents the ratio of the thermal capacity of the fluid that moves into regenerator to the thermal capacity of the solid regenerator material. the expression to define utilization () is given below: (1) where: ṁf – mass of the fluid pushed through the regenerator in one direction; cf and cs – specific heat of the fluid and the solid, respectively; ms –mass of the solid regenerator (neves bez et al. 2016). to find the optimal working point of the mcm, thot is set slightly above the tc of the working material and series of tests are run under the following conditions: 1. at different piston amplitudes, when the utilization (eq. 1) of a regenerator is known. the sample is tested at the same temperature (slightly above the tc) and piston velocity conditions. the point where the temperature span is the highest is selected to be the optimal piston amplitude for the remaining tests of the same regenerator. 2. at different piston velocities, when the optimal piston amplitude is known. the sample is tested at the same temperature (same as at the first step) and piston amplitude conditions. the point where the temperature span is at the peak is selected to be the optimal piston velocity for the remaining tests of the same regenerator. 3. at the different temperature range, when the piston amplitude and velocity is constant. when working point is known, a test against temperature change is made in order to find the peak of the temperature span of the tested sample. a) b) c) fig. 4. the mcm regenerator a) stacked plate regenerator b) top view and c) side view. geometry of the housing of the regenerators ø~38mm (outer) and h=40mm. two types of regenerators have been tested in the test machine. the parallel plate regenerator is shown in the fig. 4. a). the irregular particle regenerator is shown in fig. 4 b) and c). the mcm and their characteristics are not discussed further in this paper. more information about the both types of the regenerators might be found in bahl et al. (2016) and neves bez et al. (2016), respectively. the results for three regenerators, in the form of irregular particles (see fig. 4 b and c) are presented in this paper. all of the presented regenerators were bonded with a small amount of epoxy which is meant to maintain the mechanical integrity of the regenerator. a water based solution (2 wt%) of anti-corrosion inhibitor entek fne was used as a heat transfer liquid. a b (1) where: – mass of the fluid pushed through the regenerator in one direction; cf and cs – specific heat of the fluid and the solid, respectively; ms – mass of the solid regenerator (neves bez et al. 2016). to find the optimal working point of the mcm, thot is set slightly above the tc of the working material and series of tests are run under the following conditions: 1 at different piston amplitudes, when the utilization (eq. 1) of a regenerator is known. the sample is tested at the same temperature (slightly above the tc) and piston velocity conditions. the point where the temperature span is the highest is selected to be the optimal piston amplitude for the remaining tests of the same regenerator. 2 at different piston velocities, when the optimal piston amplitude is known. the sample is tested at the same temperature (same as at the first step) and piston amplitude conditions. the point where the temperature span is at the peak is selected to be the optimal piston velocity for the remaining tests of the same regenerator. 3 at the different temperature range, when the piston amplitude and velocity is constant. when working point is known, a test against temperature change is made in order to find the peak of the temperature span of the tested sample. two types of regenerators have been tested in the test machine. the parallel plate regenerator is shown in the fig. 4. a). the irregular particle regenerator is shown in fig. 4 b) and c). the mcm and their characteristics are not discussed further in this paper. more information about the both types of the regenerators might be found in bahl et al. (2016) and neves bez et al. (2016), respectively. the results for three regenerators, in the form of irregular particles (see fig. 4 b and c) are presented in this paper. all of the presented regenerators were bonded with a small amount of epoxy journal of sustainable architecture and civil engineering 2016/1/14 76 which is meant to maintain the mechanical integrity of the regenerator. a water based solution (2 wt%) of anti-corrosion inhibitor entek fne was used as a heat transfer liquid. all the samples have the same mass (95 g), and average specific heat (500 j/kgk) (the difference in the specific heat of the samples might be neglected) (neves bez et al. 2016). the bonding epoxy has poorer thermal properties than pure mcm, nevertheless it is necessary for structural integrity of the regenerator. thus it is important to measure the mce characteristics of the regenerators before applying the material on a larger prototypes or magnetic heat pumps. particularly this material is will be used in the enovheat (efficient novel magnetocaloric heat pumps) prototype, which is under design at dtu energy. more information can be found at the project’s home page http:// www.enovheat.dk/. fig. 4 the mcm regenerator a) stacked plate regenerator b) top view and c) side view. geometry of the housing of the regenerators ø~38mm (outer) and h=40mm. a) b) fig. 3. the test machine with the magnetic regenerator a) outside and b) inside the magnet. the test machine can be operated in different combinations of various parameters, such as a different piston (displacer) stroke (amplitude) and velocity. the heat transfer fluid flow is provided by pushing the piston backwards and forwards. in this manner the fluid velocity and volume of the flow can be controlled. the velocity of the fluid directly affects utilization, which represents the ratio of the thermal capacity of the fluid that moves into regenerator to the thermal capacity of the solid regenerator material. the expression to define utilization () is given below: (1) where: ṁf – mass of the fluid pushed through the regenerator in one direction; cf and cs – specific heat of the fluid and the solid, respectively; ms –mass of the solid regenerator (neves bez et al. 2016). to find the optimal working point of the mcm, thot is set slightly above the tc of the working material and series of tests are run under the following conditions: 1. at different piston amplitudes, when the utilization (eq. 1) of a regenerator is known. the sample is tested at the same temperature (slightly above the tc) and piston velocity conditions. the point where the temperature span is the highest is selected to be the optimal piston amplitude for the remaining tests of the same regenerator. 2. at different piston velocities, when the optimal piston amplitude is known. the sample is tested at the same temperature (same as at the first step) and piston amplitude conditions. the point where the temperature span is at the peak is er in this paper. more information about the both types of the regenerators might be found in bahl et al. (2016) and neves bez et al. (2016), respectively. the results for three regenerators, in the form of irregular particles (see fig. 4 b and c) are presented in this paper. all of the presented regenerators were bonded with a small amount of epoxy which is meant to maintain the mechanical integrity of the regenerator. a water based solution (2 wt%) of anti-corrosion inhibitor entek fne was used as a heat transfer liquid. a) b) fig. 3. the test machine with the magnetic regenerator a) outside and b) inside the magnet. the test machine can be operated in different combinations of various parameters, such as a different piston (displacer) stroke (amplitude) and velocity. the heat transfer fluid flow is provided by pushing the piston backwards and forwards. in this manner the fluid velocity and volume of the flow can be controlled. the velocity of the fluid directly affects utilization, which represents the ratio of the thermal capacity of the fluid that moves into regenerator to the thermal capacity of the solid regenerator material. the expression to define utilization () is given below: (1) where: ṁf – mass of the fluid pushed through the regenerator in one direction; cf and cs – specific heat of the fluid and the solid, respectively; ms –mass of the solid regenerator (neves bez et al. 2016). to find the optimal working point of the mcm, thot is set slightly above the tc of the working material and series of tests are run under the following conditions: 1. at different piston amplitudes, when the utilization (eq. 1) of a regenerator is known. the sample is tested at the same temperature (slightly above the tc) and piston velocity conditions. the point where the temperature span is the highest is selected to be the optimal piston amplitude for the remaining tests of the same regenerator. 2. at different piston velocities, when the optimal piston amplitude is known. the sample is tested at the same temperature (same as at the first step) and piston amplitude conditions. the point where the temperature span is at the peak is er in this paper. more information about the both types of the regenerators might be found in bahl et al. (2016) and neves bez et al. (2016), respectively. the results for three regenerators, in the form of irregular particles (see fig. 4 b and c) are presented in this paper. all of the presented regenerators were bonded with a small amount of epoxy which is meant to maintain the mechanical integrity of the regenerator. a water based solution (2 wt%) of anti-corrosion inhibitor entek fne was used as a heat transfer liquid. a) b) fig. 3. the test machine with the magnetic regenerator a) outside and b) inside the magnet. the test machine can be operated in different combinations of various parameters, such as a different piston (displacer) stroke (amplitude) and velocity. the heat transfer fluid flow is provided by pushing the piston backwards and forwards. in this manner the fluid velocity and volume of the flow can be controlled. the velocity of the fluid directly affects utilization, which represents the ratio of the thermal capacity of the fluid that moves into regenerator to the thermal capacity of the solid regenerator material. the expression to define utilization () is given below: (1) where: ṁf – mass of the fluid pushed through the regenerator in one direction; cf and cs – specific heat of the fluid and the solid, respectively; ms –mass of the solid regenerator (neves bez et al. 2016). to find the optimal working point of the mcm, thot is set slightly above the tc of the working material and series of tests are run under the following conditions: 1. at different piston amplitudes, when the utilization (eq. 1) of a regenerator is known. the sample is tested at the same temperature (slightly above the tc) and piston velocity conditions. the point where the temperature span is the highest is selected to be the optimal piston amplitude for the remaining tests of the same regenerator. 2. at different piston velocities, when the optimal piston amplitude is known. the sample is tested at the same temperature (same as at the first step) and piston amplitude conditions. the point where the temperature span is at the peak is er in this paper. more information about the both types of the regenerators might be found in bahl et al. (2016) and neves bez et al. (2016), respectively. the results for three regenerators, in the form of irregular particles (see fig. 4 b and c) are presented in this paper. all of the presented regenerators were bonded with a small amount of epoxy which is meant to maintain the mechanical integrity of the regenerator. a water based solution (2 wt%) of anti-corrosion inhibitor entek fne was used as a heat transfer liquid. in order to measure and log the temperature of the ambient, cold and hot end, the type e thermocouples and pico tc-08 thermocouple data logger (pico logger) were used. the measurable temperature range for e type thermocouple is -270 +870 °c. standard accuracy is +/1.7°c or +/0.5%. a pico logger has 8 channels for thermocouples and the cold junction compensation (cjc) measuring ambient temperature is used in this work. the features of the device are as follow: _ measureable temperature range is -270 +1820 °c; _ temperature accuracy sum of +/0.2% of reading and +/0.5 °c; _ voltage accuracy sum of +/0.2% of reading and +/-10mv; _ conversion time 100 ms per thermocouple channel; _ sampling rate is up to 10 samples per second; _ resolution 20 bits. set-up for measurements the optimal working point of the tested regenerators was at a piston amplitude of 20 mm and piston velocity 15 mm/s (φ = 0.45), see fig. 5 and fig. 6. the working point was tested only for the sample of 2 wt.% epoxy. all of the presented samples kept their mechanical integrity during the tests, indicating that 2 wt % epoxy is adequate from a mechanical standpoint. the volume of the epoxy bonding the mcm particles was varied in order to find the minimum necessary amount to maintain the mechanical integrity of the regenerators. results and discussion all the samples have the same mass (95 g), and average specific heat (500 j/kgk) (the difference in the specific heat of the samples might be neglected) (neves bez et al. 2016). the bonding epoxy has poorer thermal properties than pure mcm, nevertheless it is necessary for structural integrity of the regenerator. thus it is important to measure the mce characteristics of the regenerators before applying the material on a larger prototypes or magnetic heat pumps. particularly this material is will be used in the enovheat (efficient novel magnetocaloric heat pumps) prototype, which is under design at dtu energy. more information can be found at the project’s home page http://www.enovheat.dk/. set-up for measurements in order to measure and log the temperature of the ambient, cold and hot end, the type e thermocouples and pico tc08 thermocouple data logger (pico logger) were used. the measurable temperature range for e type thermocouple is -270 +870 °c. standard accuracy is +/1.7°c or +/ 0.5%. a pico logger has 8 channels for thermocouples and the cold junction compensation (cjc) measuring ambient temperature is used in this work. the features of the device are as follow:  measureable temperature range is -270 +1820 °c;  temperature accuracy sum of +/0.2% of reading and +/0.5 °c;  voltage accuracy sum of +/0.2% of reading and +/-10mv;  conversion time 100 ms per thermocouple channel;  sampling rate is up to 10 samples per second;  resolution 20 bits. results and discussion the optimal working point of the tested regenerators was at a piston amplitude of 20 mm and piston velocity 15 mm/s ( = 0.45), see fig. 5 and fig. 6. the working point was tested only for the sample of 2 wt.% epoxy. all of the presented samples kept their mechanical integrity during the tests, indicating that 2 wt % epoxy is adequate from a mechanical standpoint. the volume of the epoxy bonding the mcm particles was varied in order to find the minimum necessary amount to maintain the mechanical integrity of the regenerators. fig. 5. no-load temperature span as a layers regenerator. fig. 5 no-load temperature span as a function of utilization for a two layers regenerator. 77 journal of sustainable architecture and civil engineering 2016/1/14 the regenerators with 3 wt% and 4 wt% of epoxy were tested at the same working point. as it was expected, the regenerator with 2 wt% of epoxy showed the best performance: ∆tspan = 13.6 k at thot = 301 k (28 ºc). the peaks of the samples with 3 wt% and 4 wt% were ∆tspan = 12.8 k (at thot = 301 k (28 ºc)) and ∆tspan = 12.2 k (at thot = 300 k (27 ºc)), respectively. the obtained results agree with the previously published knowledge and suggest that increasing the number of layers in the regenerator in the form of powders may lead to a broader temperature span (eriksen 2016, neves bez et. al 2016). however, a more powerful and more efficient machine is necessary to allow us to perform a full test of multilayered regenerators. thus, it is planned to build an advanced testing device with higher operating frequency and an adjustable magnetic field. the main purpose of the machine would be kept the same – to test and optimize active magnetic regenerators on a small scale before implementing them in larger, more complex prototypes, such as the rotary prototypes, built fig. 6 no-load temperature span as a function of fluid velocity for a two layers regenerator fig. 7 no-load temperature span as a function of the temperature of the hot end for a two layers regenerator. fig. 6. no-load temperature span as a function of fluid velocity for a two layers regenerator. the regenerators with 3 wt% and 4 wt% of epoxy were tested at the same working point. as it was expected, the regenerator with 2 wt% of epoxy showed the best performance: ∆tspan = 13.6 k at thot = 301 k (28 ºc). the peaks of the samples with 3 wt% and 4 wt% were ∆tspan = 12.8 k (at thot = 301 k (28 ºc)) and ∆tspan = 12.2 k (at thot = 300 k (27 ºc)), respectively. fig. 7. no-load temperature span as a function of the temperature of the hot end for a two layers regenerator. the obtained results agree with the previously published knowledge and suggest that increasing the number of layers in the regenerator in the form of powders may lead to a broader temperature span (eriksen 2016, neves bez et. al 2016). however, a more powerful and more efficient machine is necessary to allow us to perform a full test of multilayered regenerators. thus, it is planned to build an advanced testing device with higher operating frequency and an adjustable magnetic field. the main purpose of the machine would be kept the same – to test and optimize active magnetic regenerators on a small scale before implementing them in larger, more complex prototypes, such as the rotary prototypes, built at dtu energy (bahl2013, eriksen 2016). the design and arrangement of the machine is not well discussed yet, though. it is clear that the new device should be designed to be very flexible with regards to materials, regenerator geometry and operating conditions. also, the available literature suggests that the temperature of a heat-sink must be decided a priori if a new device is going to be designed. finally, the efficiency and coefficient of performance (cop) of magnetocaloric prototypes has been significantly increased over the past three years – okuamura and hirano (2013) presented a device with a cop of 2.5 at a δtspan of 5 k of their previous prototype, later jacobs et al. (2014) published results about a prototype, operating at a cop above 2 at a δtspan of 10 k. the latest published prototype with a cop of 3.6 at a δtspan of 15.5 k and efficiency of 18% was developed at dtu energy, it is described in eriksen et al. (2016). conclusions a brief introduction to the mce as an alternative to the conventional vapor compression device has been given in the present paper. the existing test machine, built at dtu energy, has been described. additionally, the interested reader might find more information about the rotary prototype of the magnetic cooling technology in eriksen (2016). fig. 6. no-load temperature span as a function of fluid velocity for a two layers regenerator. the regenerators with 3 wt% and 4 wt% of epoxy were tested at the same working point. as it was expected, the regenerator with 2 wt% of epoxy showed the best performance: ∆tspan = 13.6 k at thot = 301 k (28 ºc). the peaks of the samples with 3 wt% and 4 wt% were ∆tspan = 12.8 k (at thot = 301 k (28 ºc)) and ∆tspan = 12.2 k (at thot = 300 k (27 ºc)), respectively. fig. 7. no-load temperature span as a function of the temperature of the hot end for a two layers regenerator. the obtained results agree with the previously published knowledge and suggest that increasing the number of layers in the regenerator in the form of powders may lead to a broader temperature span (eriksen 2016, neves bez et. al 2016). however, a more powerful and more efficient machine is necessary to allow us to perform a full test of multilayered regenerators. thus, it is planned to build an advanced testing device with higher operating frequency and an adjustable magnetic field. the main purpose of the machine would be kept the same – to test and optimize active magnetic regenerators on a small scale before implementing them in larger, more complex prototypes, such as the rotary prototypes, built at dtu energy (bahl2013, eriksen 2016). the design and arrangement of the machine is not well discussed yet, though. it is clear that the new device should be designed to be very flexible with regards to materials, regenerator geometry and operating conditions. also, the available literature suggests that the temperature of a heat-sink must be decided a priori if a new device is going to be designed. finally, the efficiency and coefficient of performance (cop) of magnetocaloric prototypes has been significantly increased over the past three years – okuamura and hirano (2013) presented a device with a cop of 2.5 at a δtspan of 5 k of their previous prototype, later jacobs et al. (2014) published results about a prototype, operating at a cop above 2 at a δtspan of 10 k. the latest published prototype with a cop of 3.6 at a δtspan of 15.5 k and efficiency of 18% was developed at dtu energy, it is described in eriksen et al. (2016). conclusions a brief introduction to the mce as an alternative to the conventional vapor compression device has been given in the present paper. the existing test machine, built at dtu energy, has been described. additionally, the interested reader might find more information about the rotary prototype of the magnetic cooling technology in eriksen (2016). at dtu energy (bahl2013, eriksen 2016). the design and arrangement of the machine is not well discussed yet, though. it is clear that the new device should be designed to be very flexible with regards to materials, regenerator geometry and operating conditions. also, the available literature suggests that the temperature of a heat-sink must be decided a priori if a new device is going to be designed. finally, the efficiency and coefficient of performance (cop) of magnetocaloric prototypes has been significantly increased over the past three years – okuamura and hirano (2013) presented a device with a cop of 2.5 at a δtspan of 5 k of their previous prototype, later jacobs et al. (2014) published results about a prototype, operating at a cop above 2 at a δtspan of 10 k. the latest published prototype with a cop of 3.6 at a δtspan of 15.5 k and efficiency of 18% was developed at dtu energy, it is described in eriksen et al. (2016). conclusions a brief introduction to the mce as an alternative to the conventional vapor compression device has been given in the present paper. the existing test machine, built at dtu energy, has been described. additionally, the interested reader might find more information about the rotary prototype of the magnetic cooling technology in eriksen (2016). no-load temperature spans have been presented for the regenerators with varying amounts of bonding epoxy. it is seen that the smaller amount of epoxy in the volume of the regenerator, the better is the performance. the minimal amount of epoxy should be incorporated in order to sustain the mechanical integrity of the regenerator, though. as it is presented in the results section, the utilisation for all of the tested regenerators was φ = 0.45, which corresponded to a journal of sustainable architecture and civil engineering 2016/1/14 78 piston amplitude 20 mm. the sample with the least amount of epoxy showed the best perform and temperature span δtspan=13.6°c, while the sample with 4% of epoxy showed the lowest temperature span δtspan=12.2°c. the regenerator with 3% of epoxy showed the temperature span of δtspan=12.8°c. the experiments on the same mcm with the 2% of epoxy will be continued in order to find the best configuration of the particles geometry and number of the layers in a regenerator. the authors are grateful to vacuumschmelze gmbh for providing the samples. this work was partly financed by the enovheat project which is funded by innovation fund denmark (contract no 12-132673). acknow ledgment bahl c. r. h. et al., bonded lafesih plates tested in a magnetocaloric device. international journal of refrigeration. 2016. in preparation. bahl c.r.h., engelbrecht k., eriksen d., lozano j.a., bjørk r., geyti j., nielsen k.k., smith a., pryds n. development and experimental results from a 1 kw prototype amr, int. j. refrigeration, 2013, 37:78. http://dx.doi.org/10.1016/j.ijrefrig.2013.09.001 bahl c. r. h., petersen t. f., pryds n., smith a. a versatile magnetic refrigeration test device. review of scientific instruments, 2008, 79, 093906. http:// dx.doi.org/10.1063/1.2981692 barbosa j,. lozano j., trevizoli p. magnetocaloric refrigeration research at the inct in cooling and thermophysics. 15th brazilian congress of thermal science and engineering, 2014. conference proceedings. barclay j. a., steyert w. a. active magnetic regenerator. united states patent. 1981. application no. 228,836. engelbrecht k., bahl c. r. h., nielsen k. k. experimental results for a magnetic refrigerator using three different types of magnetocaloric material regenerators. international journal of refrigeration, 2011, 34: 1132-1140. http://dx.doi.org/10.1016/j. ijrefrig.2010.11.014 engelbrecht k., jensen j. b., bahl c. r. h. experiments on a modular magnetic refrigeration device. journal of mechanical engineering 58, 2012, 1: 3-8. eriksen d. active magnetic regenerator refrigeration with rotary multi-bed technology. phd thesis submitted to dtu. 2016. eriksen d., engelbrecht k., bahl c. r. h. bjørk r. exploring the efficiency potential for an active magnetic regenerator. science and technology for the built environment, 2016, 0:1-7. eriksen d., engelbrecht k., bahl c. r. h., bjørk r., nielsen k. k., insinga a. r., pryds n. design and experimental test of a rotary active magnetic regenerator prototype. international journal of refrigeration, 2015, 58: 14-21. http://dx.doi.org/10.1016/j. ijrefrig.2015.05.004 jacobs s., auringer j., boeder a., chell j., komorowski l., leonard j., russek s., zimm c. the performance o a large-scale rotary magnetic refrigerator. international journal of refrigeration, 2014, 37: 84-91. http://dx.doi.org/10.1016/j.ijrefrig.2013.09.025 kaštil j., tětek j., tuček a. experimental investigation of small-scale magnetocaloric refrigeration. acta physica polonica a, 2013, 4 (124): 740-744. http://dx.doi.org/10.12693/aphyspola.124.740 kitanovski a., tušek j., tomc u., plaznik u., ožbolt m., poredoš a. magnetocaloric energy conversion from theory to application. switzerland: springer international publishing; 2015. lei z., haberstroh ch., odenbach s., eckert k. heat transfer enhancement in magnetic cooling by means of magnetohydrodynamic convection. international journal of refrigeration, 2016, 62: 166-176. http://dx.doi.org/10.1016/j.ijrefrig.2015.10.002 neves bez h., navickaitė k., lei t., engelbrecht k., barcza a., bahl c. r. h. epoxy-bonded la(fe,mn,si)13hz as a multi layered active magnetic regenerator. seventh iif-iir international conference on magnetic refrigeration at room temperature, thermagvii, 2016. submitted. nielsen k. k., engelbrecht k. the influence of the solid thermal conductivity on active magnetgic regenerators. j phys d appl phys, 2012, 45:145001. http:// dx.doi.org/10.1088/0022-3727/45/14/145001 okamura t., hirano n. improvement of the performance of room temperature magnetic refrigerator using gd-alloy. journal of the japan society of applied electromagnetics and mechanics, 2013, 21 (1):10-4. http://dx.doi.org/10.14243/jsaem.21.10 references 79 journal of sustainable architecture and civil engineering 2016/1/14 rowe a., tura a. experimental investigation of a three-material layered active magnetic regenerator. international journal of refrigeration, 2006, 29: 1286-1293. http://dx.doi.org/10.1016/j.ijrefrig.2006.07.012 smith a., bahl c. r. h., bjørk r., engelbrecht k., nielsen k. k., pryds n. materials challenges for high performance magnetocaloric refrigeration device. advance energy materials, 2012, 1-31. kristina navickaite phd student technical university of denmark, department of energy conversion and storage, section of electrofunctional materials main research area heat transfer, renewable energy, fluid dynamic address dtu risø campus, frederiksborgvej 399, b 779, r15, 4000 roskilde, denmark tel: +45 93 51 15 91 e-mail: knav@dtu.dk henrique neves bez phd student technical university of denmark, department of energy conversion and storage, section of electrofunctional materials main research area material science, renewable energy address dtu risø campus, frederiksborgvej 399, b 778, r19, 4000 roskilde, denmark tel: +45 51 30 83 87 e-mail: hnbe@dtu.dk kurt engelbrecht senior researcher technical university of denmark, department of energy conversion and storage, section of electrofunctional materials main research area heat transfer, renewable energy, fluid dynamic, energy conversion address dtu risø campus, frederiksborgvej 399, b 779, r26, 4000 roskilde, denmark tel: +45 46 77 56 49 e-mail: kuen@dtu.dk christian r. h. bahl senior researcher technical university of denmark, department of energy conversion and storage, section of electrofunctional materials main research area heat transfer, renewable energy, fluid dynamic, energy conversion, material science address dtu risø campus, frederiksborgvej 399, b 779, r26, 4000 roskilde, denmark tel: +45 46 77 56 49 e-mail: chrb@dtu.dk about the authors journal of sustainable architecture and civil engineering 2016/3/16 82 *corresponding author: meleni@ucy.ac.cy thermal assessment of traditional, partially subterranean dwellings in coastal and mountainous regions in the mediterranean climate. the case of cyprus http://dx.doi.org/10.5755/j01.sace.16.3.16155 eleni malaktou*, maria philokyprou, aimilios michael, andreas savvides university of cyprus, department of architecture, 75 kallipoleos street, 1678, nicosia, cyprus received 2016/08/31 accepted after revision 2016/10/14 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 82-96 doi 10.5755/j01.sace.16.3.16155 © kaunas university of technology thermal assessment of traditional, partially subterranean dwellings in coastal and mountainous regions in the mediterranean climate. the case of cyprus jsace 3/16 fully, or partially, subterranean dwellings have developed as a distinctive building type from the prehistoric to pre-industrial era in the mediterranean region, often serving specific purposes. the energy benefits of such spaces are well documented mainly through the investigation of numerous examples found in vernacular architecture. despite their environmental potentials, subterranean structures remain limited in contemporary design practices. the present paper reports on the findings of a systematic research that examines partially subterranean traditional dwellings in the coastal and mountainous regions of cyprus, an island in the eastern mediterranean. the study focuses on the environmental assessment of these spaces, through the monitoring of air temperature and relative humidity, and on a brief demonstration of various passive strategies for indoor microclimate improvements. although these structures are not very common in the vernacular architecture of the island, their scientific examination produces useful knowledge in terms of energy savings. this can inform contemporary design applications and form a basis for the drafting of environmental refurbishment guidelines, applicable for this particular building typology. the research indicates favourable temperatures and significant cooling effects in partially subterranean spaces during the hot summer period, especially in mountainous regions. temperatures in such spaces during the cold winter period are found to exhibit higher values compared to the temperatures of above-ground spaces, although they remain below comfort limits. high indoor humidity is found to be a major problem, in both the summer and winter period, in the coastal regions of the island. it is highlighted that, although partially subterranean spaces have many environmental benefits, as earth offers thermal insulation and heat storage, generalizations should be avoided since a number of varying parameters, such as the local climate, geology, natural ventilation conditions and building materials used, influence considerably their environmental performance. keywords: partially subterranean dwellings, mediterranean climate, vernacular architecture, coastal and mountainous regions, environmental design. 83 journal of sustainable architecture and civil engineering 2016/3/16 introduction fully, or partially, subterranean dwellings exhibit various typologies based on the characteristics of the natural environment such as the topography, geology and available building materials, as well as on factors related to human behaviour, such as the need for protection and privacy. such structures can be divided into two general types: the cliff-cut dwellings built into the sides of slopped terrain and the pit-like dwellings arranged around sunken courtyards normally found on plateau-located land (vegas et al. 2014). subterranean dwellings have a rich history around the mediterranean area; they are encountered in the island of santorini, greece, matera in italy, granada, almazora and guadix in spain etc. (vegas et al. 2014). these structures incorporate many environmental advantages, such as considerable time lag, dampening of daily and seasonal temperature fluctuations, especially during cold or heat waves, and noise protection (malaktou et al. 2016). considering the environmental potential of subterranean buildings, it may be argued that the protection, preservation and refurbishment of such spaces, and their introduction in contemporary architecture, promote a sustainable design approach. since subterranean structures on the island are mostly associated with vernacular domestic architecture, this research focuses on the environmental performance evaluation of representative traditional partially subterranean dwellings from two distinctly different climatic regions of cyprus; i.e., a mountainous and a coastal region. a significant number of publications investigate the environmental sustainability of vernacular architecture of cyprus, including aspects of outdoor and semi-outdoor microclimatic conditions assessment (savvides at al. 2016; thravalou, 2015); lighting performance evaluation (michael et al. 2015); natural ventilation potential (michael et al. 2014); energy consumption (florides et al. 2001); passive heating and cooling design strategies inherent in vernacular architecture (lapithis 2004; serghides 2010; philokyprou et al. 2013; philokyprou et al. 2015) and evaluation of indoor thermal conditions (philokyprou and michael 2012; michael et al. 2013). despite related research interest on environmental performance issues of the local vernacular architecture, quantitative thermal investigations still remain very limited in partially subterranean typologies. the aim of this research is to highlight the environmental potentials of such structures, namely their ability to create favourable thermal comfort conditions and, at the same time, to discern their weaknesses and deficiencies, in order to identify potential future prospects. research interest in the environmental behaviour of subterranean buildings —including thermal comfort conditions, daylight levels and energy consumption— has grown noticeably in the last decades. meir and gilead (2002) carried out onsite measurements of air temperature and relative humidity during the hot, summer period on selected dwellings in three distinctly different climatic regions of israel and provided evidence that subterranean spaces achieve significant reduction of temperatures and thermal stability. the same study however, reports issues related to inefficient natural ventilation and daylight, as well as high indoor humidity levels in the examined region that feature high ambient relative humidity. similar results, i.e. significant temperature reductions, constant indoor temperatures and high humidity levels were found by canas and martin (2005) in their study of traditional wine cellars in spain. a case study performed in iraq (kharrufa 2008) showed that the subterranean space average temperature on a july hot, summer day was 33.6°c, i.e. 4.5°c lower than the temperature of the space above-ground (38.1°c). another study by al-temeeni and harris (2004), discusses the advantages and disadvantages of subterranean structures in hot and arid climates. the advantages reported relate to minimum maintenance, enhanced noise protection, stability to earthquakes and better thermal behaviour compared to aboveground structures. it was further indicated, that subterranean structures are often the result of the hilly or mountainous topography, which makes them perfectly adapted to the landscape. among the disadvantages reported is the lack of sufficient natural ventilation and lighting, as well as the limited visual connection with the outdoors, due to the absence of windows. a study by zhai and previtali (2010), on the environmental evaluation of vernacular architecture in different locations and climates around the world, reveals that fully or partially subterranean dwellings are more frequently observed in cold climates, occasionally in hot climates and never in humid climates. background journal of sustainable architecture and civil engineering 2016/3/16 84 subterranean structures in cyprus partially subterranean dwellings in cyprus have appeared since the prehistoric period. building units of irregular plan at the neolithic settlement of ayios epiktitos–vrysi constitute distinctive examples of partially subterranean construction on the island (wright 1992; philokyprou 1998). this building configuration was favoured due to the settlement location on a steep sea cliff. however, other factors, such as camouflage from the intemperate environment or human aggression, have also led to this subterranean architecture concept (wright 1992). quite different cases are observed at the neolithic site of philia–drakos (philokyprou 1998) and at the chalcolithic sites of kalavassos–ayious and kokkinoyia/pampoules (wright 1992). in these sites, numerous pits created spaces for various purposes. some of them seem to have been hearths or ovens, while others were probably used for storage. the larger ones seem to have been used for some form of occupation (wright 1992). apart from domestic architecture, a number of burial monuments of antiquity, such as the hellenistic necropolis of the tombs of the kings in ancient paphos, also exhibited an organisation of subterranean rooms. such structures were often configured by underground peristyle courts and burial chambers carved on natural rock. during the medieval period, these burial monuments were often modified to accommodate domestic uses (hadjisavvas 2012) while, at the same time, many newly-built dwellings incorporated subterranean spaces. according to enlart (1987), the use of basement spaces in the summer was usual during that period, since these spaces offered protection from solar heat. in the subsequent historical periods, partially subterranean spaces became assimilated in the rural vernacular architecture of the island, mainly in mountainous and occasionally in coastal settlements located on hilly landscapes. these rooms were mainly utilised as storage spaces, pantries and stables (kizildere and ozsoy 1995). in the context of coastal settlements, the single-space room with a wide façade, called monochoro platymetopo, is most commonly used either as above ground or partially subterranean room. its length usually covers twice, or more, its width resulting in a shallow plan layout room. in the context of mountainous settlements, more compact configurations, such as the single-space room with a narrow façade, called monochoro stenometopo and the double-space room, called dichoro were preferred to be used either as above ground or subterranean rooms. monochoro stenometopo features a narrow facade and a deep plan layout, while dichoro resembles more a square space with a relatively deep plan layout. in the framework of this research, the thermal behaviour of partially subterranean buildings in different climatic regions of the island, i.e. coastal and mountainous regions, was examined in depth. specifically, representative partially subterranean spaces were selected for a detailed analysis in the coastal traditional settlement of maroni, located in the south coast of the island, and in the mountainous traditional settlement of askas, located in the central highlands, in troodos mountain area. although cyprus is divided into four distinct climatic regions, i.e. the coastal region (cz1), the lowland region (cz2), the semi-mountainous region (cz3) and the mountainous region (cz4), the present analysis focuses on coastal and mountainous regions for in depth investigation. this is mainly due to the fact that buildings in the lowland region rarely incorporate subterranean spaces, while buildings in semi-mountainous regions share typological and constructional features with the ones located in the mountainous region. research methodology climatic and geological context cyprus has a mediterranean climate. however, different regions of the island feature diverse climate subtypes (table 1). specifically, the coastal region (maroni) features high relative humidity throughout the year due to its proximity to the sea. as a result, diurnal temperature fluctuations are moderated, causing cool winters and relatively mild summers. the climate in the mountainous region of the central highlands (askas) features cold and wet winters and mild summers due to its high altitude. snowfall occurs frequently during the winter period. in terms of geology, table 1 briefly indicates that the south coast region, in which maroni village lies, is composed 85 journal of sustainable architecture and civil engineering 2016/3/16 mainly of sedimentary stones i.e. calcarenites, while the central highlands where askas village is located consists of igneous stones, i.e. gabbro and diabase. these locally available building materials have been extensively used in local traditional building construction. based on laboratory measurements, the thermal properties of stones, from the locality of the troodos mountain area and the south coast region, are presented in table 1. as seen in table 1, these two regions have so diverse climatic and geological conditions that it would be inappropriate to assess their potentials for subterranean construction in a uniform manner. since the hygrothermal properties of soil and building materials, as well as the climate, determine the environmental behaviour inside subterranean structures to a great extent, each geographical location requires a separate examination. coastal region (maroni) mountainous region (askas) altitude (m) 70 900 distance from the sea (km) 2 50 climatic context mean tmin–tmax for the coldest month (°c) 6.1–17.6 3.0–10.4 mean tmin–tmax for the hottest month (°c) 20.0–33.6 20.2–30.9 mean rhmin–rhmax for the coldest month (%) 34–100 12–99 mean rhmin–rhmax for the hottest month (%) 22–92 7–92 mean annual precipitation (mm) 384 699 geological context building materials sedimentary stones, i.e. calcarenites silica-rich soils, igneous stones, i.e. gabbro, diabase thermal properties of building materials thermal conductivity, λ (w/mk) 0.99 1.82 thermal diffusivity, α (m2/s) 0.67*10-6 1.07*10-6 tmin, mean min temperature; tmax, mean max temperature; rhmin, mean min relative humidity; rhmax, mean max relative humidity table 1 climatic and geological characteristics of the two regions under examination selection of case studies based on a survey of a total of 30 traditional dwellings in each settlement under study, it is established that partially subterranean dwellings account for a significant 93% of the mountainous settlement of askas, while they appear at a more limited rate of 13% in the coastal settlement of maroni. this is in line with related literature documenting that partially subterranean dwellings are most commonly found in the mountainous settlements of the island. onsite measurements were conducted in five representative traditional dwellings (table 2); two located in the coastal region (ca and cb) and three in the mountainous region (ma, mb and mc). in each case study building, environmental data recordings were made for one partially subterranean space, i.e. ca1, cb1, cb2, ma1, mb1 and mc1, and one above-ground space, i.e. ca2, cb3, cb4, ma2, mb2 and mc2, for comparative analysis. in case study cb, measurements were taken in two partially subterranean spaces and two above-ground reference spaces. the case studies are representative of the prevailing traditional building materials and cover a variety of typologies, as well as spatial configurations applied on the vernacular architecture of the island (table 3). the partially subterranean spaces under study in the coastal region of maroni journal of sustainable architecture and civil engineering 2016/3/16 86 table 2 maps of maroni and askas settlements presenting case study buildings. sections and images of case study partially subterranean spaces coastal region (maroni) ca1 cb1 cb2 onsite measurements and data analysis environmental data, i.e. air temperature and relative humidity, was recorded during the hot, summer period (18th to 31st july 2014) and cold, winter period (13th to 22nd january 2015) to provide an environmental performance evaluation of the partially subterranean spaces, during both extreme climatic conditions. for the environmental monitoring of indoor spaces, easylog data loggers, were placed 1.5 m table 2. maps of maroni and askas settlements presenting case study buildings. sections and images of case study partially subterranean spaces coastal region (maroni) ca1 cb1 cb2 mountainous region (askas) ma1 mb1 mc1   table 3. typological, spatial and constructional details of partially subterranean spaces typology or. window masonry roof type r* type configuration coastal region (maroni) ca1 double-space ne low + shutters single-sided sedimentary stones & mud in-between decked by upper storey 2.0 cb1 single-space e–w low & top + shutters double-sided decked by upper storey 1.6 cb2 single-space e–w top double-sided flat 1.9 mountainous region (askas) ma1 single-space igneous stones & mud in-between decked by upper storey 2.1 mb1  single-space e 1.9 mc1 double-space ne fenestration on door 1.7 *area of building envelope which has contact with soil to floor area ratio mb ma mc ca cb mountainous region (askas) ma1 mb1 mc1 onsite measurements and data analysis environmental data, i.e. air temperature and relative humidity, was recorded during the hot, summer period (18th to 31st july 2014) and cold, winter period (13th to 22nd january 2015) to provide an environmental performance evaluation of the partially subterranean spaces, during both extreme climatic conditions. for the environmental monitoring of indoor spaces, easylog data loggers, were placed 1.5 m table 2. maps of maroni and askas settlements presenting case study buildings. sections and images of case study partially subterranean spaces coastal region (maroni) ca1 cb1 cb2 mountainous region (askas) ma1 mb1 mc1   table 3. typological, spatial and constructional details of partially subterranean spaces typology or. window masonry roof type r* type configuration coastal region (maroni) ca1 double-space ne low + shutters single-sided sedimentary stones & mud in-between decked by upper storey 2.0 cb1 single-space e–w low & top + shutters double-sided decked by upper storey 1.6 cb2 single-space e–w top double-sided flat 1.9 mountainous region (askas) ma1 single-space igneous stones & mud in-between decked by upper storey 2.1 mb1  single-space e 1.9 mc1 double-space ne fenestration on door 1.7 *area of building envelope which has contact with soil to floor area ratio mb ma mc ca cb table 3 typological, spatial and constructional details of partially subterranean spaces typology or. window masonry roof type r* type configuration coastal region (maroni) ca1 double-space ne low + shutters single-sided sedimentary stones & mud in-between decked by upper storey 2.0 cb1 single-space e–w low & top + shutters double-sided decked by upper storey 1.6 cb2 single-space e–w top double-sided flat 1.9 mountainous region (askas) ma1 single-space igneous stones & mud in-between decked by upper storey 2.1 mb1 single-space e 1.9 mc1 doublespace ne fenestration on door 1.7 settlement comprise thick stone-built masonries (0.5 m thick) constructed by local, almost rectangular, sedimentary stones and by a limited number of window openings (table 3). case study ca1 is a representative example of the double-space (dichoro) typology while case studies cb1 and *area of building envelope which has contact with soil to floor area ratio 87 journal of sustainable architecture and civil engineering 2016/3/16 cb2 are representative of the wide façade single-space (monochoro platymetopo) typology which generally prevails among the maroni built stock. the three case studies host main daily activities. the partially subterranean spaces under study in the mountainous region of askas settlement are constructed by local igneous stone, approximately 0.5 m thick. case studies ma1 and mb1 are representative of the narrow façade single-space (monochoro stenometopo) and wide façade single-space (monochoro platymetopo) typology respectively, while mc1 features the double-space (dichoro) typology. the entrance doors are the only means of fenestration in the selected case studies. case studies ma1 and mb1 have preserved their original use as storage spaces while case study mc1 has been converted into a main living space. onsite measurements and data analysis results environmental data, i.e. air temperature and relative humidity, was recorded during the hot, summer period (18th to 31st july 2014) and cold, winter period (13th to 22nd january 2015) to provide an environmental performance evaluation of the partially subterranean spaces, during both extreme climatic conditions. for the environmental monitoring of indoor spaces, easylog data loggers, were placed 1.5 m above floor level and recordings were made at 30-minute intervals. outdoor measurements were taken with vantagepro weather stations in each of the settlements under examination. the collected microclimatic data, i.e., mean average, minimum and maximum values of temperature and relative humidity and mean temperature fluctuations, are presented in comprehensive tables for comparative analysis. in addition, a regression analysis method was used to relate indoor temperature data to outdoor temperatures. thermal performance during the hot summer period the analysis of the onsite recordings in partially subterranean spaces for coastal and mountainous regions during the hot, summer period is presented below. the monitoring results in the coastal region during the hot summer period show that maximum temperatures in partially subterranean spaces remain significantly lower compared to the temperatures of the above-ground reference spaces and the outdoor environment. more specifically, mean maximum temperature ranges from 27.4 to 29.1°c in partially subterranean spaces, from 29.2 to 33.1°c in above-ground reference spaces while the mean maximum temperature in the outdoor environment is 30.4°c (table 4). measurements in partially subterranean spaces, during the hottest day of the monitoring period, indicate a significant reduction of the maximum outdoor temperature (between 3.4 and 4.9°c). mean diurnal temperature fluctuations range between 0.1 and 0.7°c, indicating that temperatures in partially subterranean spaces remain fairly constant. on the other hand, relative humidity in all three case study spaces remains stable, —i.e. with small fluctuations from 2 to 7%— exhibiting high values nevertheless. specifically, relative humidity within the acceptable limits of 40–70% is observed only for 52%, 6% and 18% of the registered data in spaces ca1, cb1 and cb2 respectively (table 4). in contrast, the above-ground reference spaces present sufficient performance in terms of perceived humidity; all the registered data in cases ac1 and bc3, as well as 84% of the registered data in bc2, remains below the 70% upper acceptable limit. in general, although partially subterranean spaces achieve significant reductions in terms of maximum temperatures, relative humidity exceeds acceptable levels and thus creates uncomfortable conditions. regarding the mountainous regions, it is established that the mean maximum temperatures in partially subterranean spaces range between 24.4 and 25.7°c during the hot, summer period. mean outdoor maximum temperature for the same period is 28.3°c, while mean maximum temperatures vary between 28.2 and 29°c in above-ground reference spaces. these results indicate that mean maximum temperature in partially subterranean spaces remains significantly lower compared to above-ground spaces and the outdoor environment. during the hottest day of the journal of sustainable architecture and civil engineering 2016/3/16 88 mean air temperature (°c) tmax_out-tmax_in in hottest day (°c) temp. limits (°c) mean rh (%) % of data in which rh = 40–70% rh limits (%)avg max min fluct avg max min partially subterranean spaces – coastal region (maroni) out. 26.8 30.4 23.1 7.3 32.4* 21.6–32.4 74 87 61 39–93 ca1 29.0 29.1 29.0 0.1 3.4 29.0–29.5 70 71 69 52 68–73 cb1 27.9 28.0 27.8 0.2 4.4 27.5–28.5 73 74 72 6 69–80 cb2 27.0 27.4 26.7 0.7 4.9 25.5–27.5 75 78 71 18 60–86 partially subterranean spaces – mountainous region (askas) out. 24.3 28.3 20.6 7.6 31.3* 17.3–31.3 53 75 33 23–92 ma1 23.9 24.4 23.4 1.0 6.3 23.0–25.0 55 62 46 99 36–68 mb1 24.3 24.7 23.8 0.9 5.8 23.0–25.5 58 61 54 100 50–63 mc1 25.5 25.7 25.3 0.4 5.3 25.0–26.5 57 59 54 100 51–66 above-ground reference spaces – coastal region (maroni) ca2 31.2 33.1 29.5 3.5 -1.6 29.0–34.0 59 61 56 100 52–63 cb3 28.7 29.8 27.7 2.1 1.4 26.5–31.0 65 69 62 84 49–74 cb4 28.8 29.2 28.4 1.2 2.9 28.0–29.5 66 67 65 100 62–69 above-ground reference spaces – mountainous region (askas) ma2 27.0 28.2 25.7 2.5 1.3 25.0–30.0 46 51 41 91 36–57 mb2 27.4 29.0 25.8 3.1 0.3 25.0–31.0 52 58 46 99 35–66 mc2 27.4 28.6 26.3 2.4 0.8 25.5–30.5 50 52 48 100 46–62 tmax_in, maximum indoor temperature ; tmax_out, maximum outdoor temperature; rh, relative humidity; * highest outdoor temperature table 4 summary of registered environmental data during the hot, summer period monitoring period, the indoor maximum temperature reduction in partially subterranean spaces ranges from 5.3 to 6.3°c. despite the relatively large mean diurnal temperature fluctuation of the external environment, i.e. 7.6°c, mean. temperature fluctuations in partially subterranean spaces are limited to 0.4–1.0°c indicating great thermal stability. relative humidity in partially subterranean spaces remains stable, i.e. with variations from 5 to 16%, and within the acceptable comfort limits of 40–70%. in terms of both summer temperatures and perceived humidity during the summer period, partially subterranean spaces generally create favourable conditions. in an attempt to investigate whether the area of the building envelope in contact with the soil affects indoor temperatures, the ratio r, i.e. the area of the building envelope which has contact with soil to floor area ratio (table 3), was correlated with mean maximum temperatures in partially subterranean spaces. it is noted that when ratio r of a space increases, the mean maximum temperature decreases, resulting in cooler temperatures. deviations from the trend-lines occur in the case of ca1. the influential variables that may be related to this deviation are the orientation, ventilation conditions, window-to-floor area ratio and exposure of the building envelope, i.e. external walls and roof, to ambient conditions. along with ratio r, the above variables constitute important factors that affect temperatures in partially subterranean spaces. it is noted that the set of data correlating ratio r to indoor temperatures refers to a small number of case studies and for this reason it is not possible to validate these results. 89 journal of sustainable architecture and civil engineering 2016/3/16 thermal performance during the cold winter period the analysis of the onsite recordings in partially subterranean spaces in coastal and mountainous regions during the cold, winter period is presented below. based on the onsite recordings, mean maximum temperatures in the partially subterranean spaces of coastal regions are found to be low, ranging between 14.4 and 15.1°c during the cold winter period, whereas outdoor mean maximum temperature is 16°c. mean maximum temperature in the spaces under study remains lower compared to the outdoor environment (table 5). however, mean maximum temperatures in partially subterranean spaces remain higher than the temperatures of the above-ground reference spaces, which range from 13.5 to 14°c. mean diurnal temperature fluctuations in partially subterranean spaces are limited to 0.1 to 0.2°c. due to their high thermal stability, partially subterranean spaces present a beneficial thermal effect during night-time hours when temperatures are minimal. specifically, mean minimum temperature in partially subterranean spaces ranges from 14.2 to 15°c, from 12.2 to 13°c in above-ground reference spaces while the mean minimum temperature in the outdoor environment is 10.2°c. during the monitoring period, 96%, 5% and 0% of the registered relative humidity data in partially subterranean spaces ca1, cb1 and cb2 respectively remains below the 70% upper acceptable limit. based on the above results, it is established that case study ca1, which is the warmest space, remains mean air temperature (°c) tmin_in-tmin_out in coldest day (°c) temp. limits (°c) mean rh (%) % of data in which rh = 40–70% rh limits (%)avg max min fluct avg max min partially subterranean spaces – coastal region (maroni) out. 12.9 16.0 10.2 5.8 8.3* 8.3–17.9 76 87 63 51–91 ca1 15.0 15.1 15.0 0.1 6.7 15.0–15.5 65 66 64 96 57–71 cb1 14.3 14.4 14.2 0.2 5.7 14.0–15.5 75 76 73 5 69–80 cb2 14.4 14.5 14.3 0.2 6.2 14.0–15.0 78 79 77 0 72–82 partially subterranean spaces – mountainous region (askas) out. 7.1 9.7 5.0 4.7 2.6* 2.6–16.3 81 93 67 9–95 ma1 8.2 8.4 8.0 0.4 4.9 7.0–9.5 73 75 70 15 61–77 mb1 8.2 8.5 8.0 0.5 4.9 7.0–9.5 75 77 74 7 65–79 mc1 9.8 9.9 9.7 0.2 6.9 9.5–11.0 60 61 59 100 56–64 above-ground reference spaces – coastal region (maroni) ca2 12.9 14.0 12.2 1.8 5.7 11.5–16.5 72 74 71 8 68–76 cb3 13.2 13.9 12.7 1.3 5.7 12.0–15.0 73 74 72 16 68–78 cb4 13.2 13.5 13.0 0.5 5.2 12.0–14.5 75 77 75 4 69–83 above-ground reference spaces – mountainous region (askas) ma2 5.7 6.4 5.1 1.3 1.9 4.0–8.5 82 83 80 0 77–85 mb2 6.3 7.0 5.7 1.3 3.4 4.5–9.5 79 80 79 0 76–82 mc2 7.1 7.8 6.5 1.3 3.9 5.5–10.5 72 73 71 0 70–77 table 5 summary of registered environmental data during the cold, winter period tmin_in, minimum indoor temperature; tmin_out, minimum outdoor temperature; rh, relative humidity ; * lowest outdoor temperature journal of sustainable architecture and civil engineering 2016/3/16 90 drier compared to the other two examined partially subterranean spaces. at the same time, relative humidity in above-ground reference spaces satisfies comfort limits for only 8%, 16% and 4% of the registered data in the case of ca2, cb3 and cb4 respectively. the analysis indicates that some environmental limitations occur in partially subterranean spaces during winter due to high relative humidity and low temperatures. regarding the partially subterranean spaces of mountainous regions, the monitoring results indicate that mean maximum temperatures remain lower, or slightly above, the mean maximum temperature of the outdoor environment during the cold, winter period (table 5). specifically, the partially subterranean spaces under study exhibit a range of mean maximum temperatures of 8.4–9.9°c when outdoor mean maximum temperature is 9.7°c. nevertheless, mean maximum temperatures in partially subterranean spaces remain higher than the temperatures of the aboveground reference spaces (6.4–7.8°c). mean diurnal temperature fluctuations in the partially subterranean spaces under study are limited to 0.2–0.5°c. it is worth mentioning that partially subterranean spaces exhibit higher mean minimum temperatures (8.0–9.7°c) compared to the above-ground reference spaces (5.1–6.5°c). it is also demonstrated that 15%, 7% and 100% of the registered relative humidity data remains within the acceptable comfort limits for the partially subterranean spaces ma1, mb1 and mc1 respectively. this indicates that case study mc1, which is the warmest space, remains drier compared to the other partially subterranean spaces. relative humidity in the above-ground reference spaces always falls outside the acceptable limits. overall, high humidity levels (recorded in two case studies), and low temperatures inside partially subterranean spaces, result in cold and wet indoor conditions during winter. cooling and warming effect estimations a further quantitative analysis of the cooling and warming effects of partially subterranean spaces during the summer and winter period is also performed (table 6 & 7). table 6α indicates that during the summer period, maximum temperatures (tmax), recorded in partially subterranean and above-ground spaces, present a linear correlation with the difference between the maximum ambient air temperature and indoor maximum temperature (tmax_d = tmax_out-tmax_in). the analysis shows that ambient maximum air temperature affects the level of cooling inside the rooms – the higher the ambient maximum air temperature the stronger the cooling effect is. the steeper slope of the graph-line representing partially subterranean spaces, as opposed to above-ground spaces, confirms that the cooling effect in the former case is stronger. more specifically, if the maximum outdoor temperature increases by 1°c, it is predicted that the cooling effect values will be enhanced by 0.9–1.0°c for partially subterranean spaces and by 0.6°c for above-ground spaces. it is worth mentioning that maximum temperatures inside partially subterranean spaces in the coastal region fall below outdoor maxima when outdoor temperature exceeds 28.2°c while, in above-ground spaces, the maximum temperature falls below the relative outdoor whereby the outdoor temperature equates to 28.8°c. correspondingly, in the mountainous region the temperature threshold is estimated to 24.6°c for partially subterranean spaces and 28.7°c for aboveground spaces. during the winter period, maximum temperatures (tmax) inside the case study rooms also present a strong linear correlation with the difference between the maximum ambient air temperature and indoor maximum temperature (tmax_d) (table 6β). the results indicate that outdoor maximum air temperature values affect the warming effect inside the examined indoor spaces; the lower the outdoor maximum temperature the stronger the warming effect is. applying the resulted regression, when outdoor maximum temperature decreases by 1°c, the average warming effect values are estimated to be enhanced by 0.8–0.9°c for partially subterranean spaces and by 0.6°c for above-ground spaces. maximum temperatures in partially subterranean spaces, located in the coastal region, rise above maximum outdoor temperature, when maximum outdoor temperature 91 journal of sustainable architecture and civil engineering 2016/3/16 table 6 linear regression results for partially subterranean and above-ground spaces. regression is performed between tmax_in and tmax_d (tmax_ out-tmax_in) that the cooling effect values will be enhanced by 0.9–1.0°c for partially subterranean spaces and by 0.6°c for above-ground spaces. it is worth mentioning that maximum temperatures inside partially subterranean spaces in the coastal region fall below outdoor maxima when outdoor temperature exceeds 28.2°c while, in above-ground spaces, the maximum temperature falls below the relative outdoor whereby the outdoor temperature equates to 28.8°c. correspondingly, in the mountainous region the temperature threshold is estimated to 24.6°c for partially subterranean spaces and 28.7°c for aboveground spaces. during the winter period, maximum temperatures (tmax) inside the case study rooms also present a strong linear correlation with the difference between the maximum ambient air temperature and indoor maximum temperature (tmax_d) (table 6β). the results indicate that outdoor maximum air temperature values affect the warming effect inside the examined indoor spaces; the lower the outdoor maximum temperature the stronger the warming effect is. applying the resulted regression, when outdoor maximum temperature decreases by 1°c, the average warming effect values are estimated to be enhanced by 0.8– 0.9°c for partially subterranean spaces and by 0.6°c for above-ground spaces. maximum temperatures in partially subterranean spaces, located in the coastal region, rise above maximum outdoor temperature, when maximum outdoor temperature is equal to, or lower than, 14.4°c. the temperature threshold for above-ground spaces is estimated to 12.0°c. similar relations are observed for mountainous regions whereby the temperature threshold is estimated to be 8.7°c and 5.5°c for partially subterranean spaces and above-ground spaces respectively. table 6. linear regression results for partially subterranean and above-ground spaces. regression is performed between tmax_in and tmax_d (tmax_out-tmax_in) summer winter b r² tmax_out lower limit in which tmax_d ≥ 0 cooling effect for every 1°c increase of tmax_out b r² tmax_out upper limit in which tmax_d ≤ 0 warming effect for every 1°c decrease of tmin_out partially subterranean spaces c 1.0 0.68 28.2 1.0 0.9 0.93 14.4 0.9 m 0.9 0.87 24.6 0.9 0.8 0.93 8.7 0.8 reference above-ground spaces c* 0.6 0.63 28.8 0.6 0.6 0.81 12.0 0.6 m 0.6 0.72 28.7 0.6 0.6 0.83 5.5 0.6 *ca2 was excluded from the correlation analysis of the summer environmental monitoring data; b, slope; r2, correlation coefficient y = 0.97x 27.31 r² = 0.68 y = 0.90x 22.17 r² = 0.87 y = 0.59x 17.01 r² = 0.63 y = 0.57x 16.35 r² = 0.72 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 15 18 20 23 25 28 30 33 35 t m ax _d = t m ax _o ut -t m ax _i n (° c ) tmax_out (°c) y = 0.87x 12.57 r² = 0.93 y = 0.84x 7.34 r² = 0.93 y = 0.60x 7.18 r² = 0.81 y = 0.63x 3.47 r² = 0.83 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 0 3 5 8 10 13 15 18 20 t m ax _d = t m ax _o ut -t m ax _i n (° c ) tmax_out (°c) increasing warming effectincreasing cooling effecta b that the cooling effect values will be enhanced by 0.9–1.0°c for partially subterranean spaces and by 0.6°c for above-ground spaces. it is worth mentioning that maximum temperatures inside partially subterranean spaces in the coastal region fall below outdoor maxima when outdoor temperature exceeds 28.2°c while, in above-ground spaces, the maximum temperature falls below the relative outdoor whereby the outdoor temperature equates to 28.8°c. correspondingly, in the mountainous region the temperature threshold is estimated to 24.6°c for partially subterranean spaces and 28.7°c for aboveground spaces. during the winter period, maximum temperatures (tmax) inside the case study rooms also present a strong linear correlation with the difference between the maximum ambient air temperature and indoor maximum temperature (tmax_d) (table 6β). the results indicate that outdoor maximum air temperature values affect the warming effect inside the examined indoor spaces; the lower the outdoor maximum temperature the stronger the warming effect is. applying the resulted regression, when outdoor maximum temperature decreases by 1°c, the average warming effect values are estimated to be enhanced by 0.8– 0.9°c for partially subterranean spaces and by 0.6°c for above-ground spaces. maximum temperatures in partially subterranean spaces, located in the coastal region, rise above maximum outdoor temperature, when maximum outdoor temperature is equal to, or lower than, 14.4°c. the temperature threshold for above-ground spaces is estimated to 12.0°c. similar relations are observed for mountainous regions whereby the temperature threshold is estimated to be 8.7°c and 5.5°c for partially subterranean spaces and above-ground spaces respectively. table 6. linear regression results for partially subterranean and above-ground spaces. regression is performed between tmax_in and tmax_d (tmax_out-tmax_in) summer winter b r² tmax_out lower limit in which tmax_d ≥ 0 cooling effect for every 1°c increase of tmax_out b r² tmax_out upper limit in which tmax_d ≤ 0 warming effect for every 1°c decrease of tmin_out partially subterranean spaces c 1.0 0.68 28.2 1.0 0.9 0.93 14.4 0.9 m 0.9 0.87 24.6 0.9 0.8 0.93 8.7 0.8 reference above-ground spaces c* 0.6 0.63 28.8 0.6 0.6 0.81 12.0 0.6 m 0.6 0.72 28.7 0.6 0.6 0.83 5.5 0.6 *ca2 was excluded from the correlation analysis of the summer environmental monitoring data; b, slope; r2, correlation coefficient y = 0.97x 27.31 r² = 0.68 y = 0.90x 22.17 r² = 0.87 y = 0.59x 17.01 r² = 0.63 y = 0.57x 16.35 r² = 0.72 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 15 18 20 23 25 28 30 33 35 t m ax _d = t m ax _o ut -t m ax _i n (° c ) tmax_out (°c) y = 0.87x 12.57 r² = 0.93 y = 0.84x 7.34 r² = 0.93 y = 0.60x 7.18 r² = 0.81 y = 0.63x 3.47 r² = 0.83 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 0 3 5 8 10 13 15 18 20 t m ax _d = t m ax _o ut -t m ax _i n (° c ) tmax_out (°c) increasing warming effectincreasing cooling effecta b that the cooling effect values will be enhanced by 0.9–1.0°c for partially subterranean spaces and by 0.6°c for above-ground spaces. it is worth mentioning that maximum temperatures inside partially subterranean spaces in the coastal region fall below outdoor maxima when outdoor temperature exceeds 28.2°c while, in above-ground spaces, the maximum temperature falls below the relative outdoor whereby the outdoor temperature equates to 28.8°c. correspondingly, in the mountainous region the temperature threshold is estimated to 24.6°c for partially subterranean spaces and 28.7°c for aboveground spaces. during the winter period, maximum temperatures (tmax) inside the case study rooms also present a strong linear correlation with the difference between the maximum ambient air temperature and indoor maximum temperature (tmax_d) (table 6β). the results indicate that outdoor maximum air temperature values affect the warming effect inside the examined indoor spaces; the lower the outdoor maximum temperature the stronger the warming effect is. applying the resulted regression, when outdoor maximum temperature decreases by 1°c, the average warming effect values are estimated to be enhanced by 0.8– 0.9°c for partially subterranean spaces and by 0.6°c for above-ground spaces. maximum temperatures in partially subterranean spaces, located in the coastal region, rise above maximum outdoor temperature, when maximum outdoor temperature is equal to, or lower than, 14.4°c. the temperature threshold for above-ground spaces is estimated to 12.0°c. similar relations are observed for mountainous regions whereby the temperature threshold is estimated to be 8.7°c and 5.5°c for partially subterranean spaces and above-ground spaces respectively. table 6. linear regression results for partially subterranean and above-ground spaces. regression is performed between tmax_in and tmax_d (tmax_out-tmax_in) summer winter b r² tmax_out lower limit in which tmax_d ≥ 0 cooling effect for every 1°c increase of tmax_out b r² tmax_out upper limit in which tmax_d ≤ 0 warming effect for every 1°c decrease of tmin_out partially subterranean spaces c 1.0 0.68 28.2 1.0 0.9 0.93 14.4 0.9 m 0.9 0.87 24.6 0.9 0.8 0.93 8.7 0.8 reference above-ground spaces c* 0.6 0.63 28.8 0.6 0.6 0.81 12.0 0.6 m 0.6 0.72 28.7 0.6 0.6 0.83 5.5 0.6 *ca2 was excluded from the correlation analysis of the summer environmental monitoring data; b, slope; r2, correlation coefficient y = 0.97x 27.31 r² = 0.68 y = 0.90x 22.17 r² = 0.87 y = 0.59x 17.01 r² = 0.63 y = 0.57x 16.35 r² = 0.72 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 15 18 20 23 25 28 30 33 35 t m ax _d = t m ax _o ut -t m ax _i n (° c ) tmax_out (°c) y = 0.87x 12.57 r² = 0.93 y = 0.84x 7.34 r² = 0.93 y = 0.60x 7.18 r² = 0.81 y = 0.63x 3.47 r² = 0.83 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 0 3 5 8 10 13 15 18 20 t m ax _d = t m ax _o ut -t m ax _i n (° c ) tmax_out (°c) increasing warming effectincreasing cooling effecta b summer winter b r² tmax_out lower limit in which tmax_d ≥ 0 cooling effect for every 1°c increase of tmax_out b r² tmax_out upper limit in which tmax_d ≤ 0 warming effect for every 1°c decrease of tmin_out partially subterranean spaces c 1.0 0.68 28.2 1.0 0.9 0.93 14.4 0.9 m 0.9 0.87 24.6 0.9 0.8 0.93 8.7 0.8 reference above-ground spaces c* 0.6 0.63 28.8 0.6 0.6 0.81 12.0 0.6 m 0.6 0.72 28.7 0.6 0.6 0.83 5.5 0.6 *ca2 was excluded from the correlation analysis of the summer environmental monitoring data; b, slope; r2, correlation coefficient is equal to, or lower than, 14.4°c. the temperature threshold for above-ground spaces is estimated to 12.0°c. similar relations are observed for mountainous regions whereby the temperature threshold is estimated to be 8.7°c and 5.5°c for partially subterranean spaces and above-ground spaces respectively. results of the regression analysis using the daily values of the minimum air temperature are given in table 7. it is shown that the minimum air temperatures (tmin) of the examined spaces present a good inverse correlation with the difference between the minimum indoor temperature and minimum ambient air temperature (tmin_d = tmin_in-tmin_out) during the summer period (table 7a). the higher the minimum outdoor temperature the stronger the cooling effect inside the examined spaces is. the cooling effect patterns appear more intense in partially subterranean spaces than in above-ground spaces, i.e. for every 1°c increase of outdoor minimum temperature the average cooling effect is estimated to be 0.9°c and 0.8°c for partially subterranean spaces and aboveground spaces, respectively. furthermore, the shift of the lines representing partially subterranean spaces below the lines of above-ground spaces indicates that lower minimum temperatures generally occur in the case of the former. during the winter period, minimum temperatures (tmin) inside the examined spaces are inversely correlated with the difference between minimum indoor temperature and minimum ambient air temperature (tmin_d). table 7b indicates that the warming effects of indoor spaces are strongly associated with colder days, i.e. with lower minimum temperatures. in addition, the warming effect journal of sustainable architecture and civil engineering 2016/3/16 92 of the above-ground spaces is found to be weaker than in partially subterranean rooms. based on the resulting regression, when the minimum outdoor temperature decreases by 1°c, the average warming effect enhances by 0.8–0.9°c for partially subterranean spaces and 0.6°c for aboveground spaces. indoor minimum temperatures in partially subterranean and above-ground spaces in coastal regions remain above outdoor minimum temperatures when outdoor minimum temperature is equal to, or lower than, 15.1°c and 14°c respectively. in the case of mountainous regions, these values are estimated to reach 9.7°c and 6.2°c in partially subterranean and aboveground spaces respectively. these results indicate that partially subterranean spaces achieve minimum temperatures higher than those of the ambient environment for a greater outdoor temperature range than above-ground spaces. results of the regression analysis using the daily values of the minimum air temperature are given in table 7. it is shown that the minimum air temperatures (tmin) of the examined spaces present a good inverse correlation with the difference between the minimum indoor temperature and minimum ambient air temperature (tmin_d = tmin_in-tmin_out) during the summer period (table 7a). the higher the minimum outdoor temperature the stronger the cooling effect inside the examined spaces is. the cooling effect patterns appear more intense in partially subterranean spaces than in above-ground spaces, i.e. for every 1°c increase of outdoor minimum temperature the average cooling effect is estimated to be 0.9°c and 0.8°c for partially subterranean spaces and above-ground spaces, respectively. furthermore, the shift of the lines representing partially subterranean spaces below the lines of above-ground spaces indicates that lower minimum temperatures generally occur in the case of the former. during the winter period, minimum temperatures (tmin) inside the examined spaces are inversely correlated with the difference between minimum indoor temperature and minimum ambient air temperature (tmin_d). table 7b indicates that the warming effects of indoor spaces are strongly associated with colder days, i.e. with lower minimum temperatures. in addition, the warming effect of the aboveground spaces is found to be weaker than in partially subterranean rooms. based on the resulting regression, when the minimum outdoor temperature decreases by 1°c, the average warming effect enhances by 0.8–0.9°c for partially subterranean spaces and 0.6°c for above-ground spaces. indoor minimum temperatures in partially subterranean and above-ground spaces in coastal regions remain above outdoor minimum temperatures when outdoor minimum temperature is equal to, or lower than, 15.1°c and 14°c respectively. in the case of mountainous regions, these values are estimated to reach table 7. linear regression results for partially subterranean and above-ground spaces. regression is performed between tmin_in and tmin_d (tmin_in-tmin_out) summer winter b r² tmin_out lower limit in which tmin_d ≤ 0 cooling effect for every 1°c increase of tmin_out b r² tmin_out upper limit in which tmin_d ≥ 0 warming effect for every 1°c decrease of tmin_out partially subterranean spaces c* -0.9 0.67 27.8 0.9 -0.9 0.89 15.1 0.9 m -0.9 0.82 24.6 0.9 -0.8 0.67 9.7 0.8 reference above-ground spaces c -0.8 0.62 29.6 0.8 -0.6 0.72 14.0 0.6 m -0.8 0.91 27.0 0.8 -0.6 0.67 6.2 0.6 *ca1 was excluded from the correlation analysis of the summer environmental monitoring data; b, slope; r2, correlation coefficient y = -0.8992x + 24.958 r² = 0.6713 y = -0.898x + 22.053 r² = 0.8227 y = -0.7574x + 22.435 r² = 0.6175 y = -0.8378x + 22.582 r² = 0.9148 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 15 18 20 23 25 28 30 33 35 tmin_out (°c) t m in _d = t m in _i nt m in _o ut (° c ) y = -0.8796x + 13.278 r² = 0.8923 y = -0.7556x + 7.3116 r² = 0.6741 y = -0.6351x + 8.8965 r² = 0.7185 y = -0.6031x + 3.7491 r² = 0.6652 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 0 3 5 8 10 13 15 18 20 tmin_out t m in _d = t m in _i nt m in _o ut (° c ) increasing warming effectincreasing cooling effecta b results of the regression analysis using the daily values of the minimum air temperature are given in table 7. it is shown that the minimum air temperatures (tmin) of the examined spaces present a good inverse correlation with the difference between the minimum indoor temperature and minimum ambient air temperature (tmin_d = tmin_in-tmin_out) during the summer period (table 7a). the higher the minimum outdoor temperature the stronger the cooling effect inside the examined spaces is. the cooling effect patterns appear more intense in partially subterranean spaces than in above-ground spaces, i.e. for every 1°c increase of outdoor minimum temperature the average cooling effect is estimated to be 0.9°c and 0.8°c for partially subterranean spaces and above-ground spaces, respectively. furthermore, the shift of the lines representing partially subterranean spaces below the lines of above-ground spaces indicates that lower minimum temperatures generally occur in the case of the former. during the winter period, minimum temperatures (tmin) inside the examined spaces are inversely correlated with the difference between minimum indoor temperature and minimum ambient air temperature (tmin_d). table 7b indicates that the warming effects of indoor spaces are strongly associated with colder days, i.e. with lower minimum temperatures. in addition, the warming effect of the aboveground spaces is found to be weaker than in partially subterranean rooms. based on the resulting regression, when the minimum outdoor temperature decreases by 1°c, the average warming effect enhances by 0.8–0.9°c for partially subterranean spaces and 0.6°c for above-ground spaces. indoor minimum temperatures in partially subterranean and above-ground spaces in coastal regions remain above outdoor minimum temperatures when outdoor minimum temperature is equal to, or lower than, 15.1°c and 14°c respectively. in the case of mountainous regions, these values are estimated to reach table 7. linear regression results for partially subterranean and above-ground spaces. regression is performed between tmin_in and tmin_d (tmin_in-tmin_out) summer winter b r² tmin_out lower limit in which tmin_d ≤ 0 cooling effect for every 1°c increase of tmin_out b r² tmin_out upper limit in which tmin_d ≥ 0 warming effect for every 1°c decrease of tmin_out partially subterranean spaces c* -0.9 0.67 27.8 0.9 -0.9 0.89 15.1 0.9 m -0.9 0.82 24.6 0.9 -0.8 0.67 9.7 0.8 reference above-ground spaces c -0.8 0.62 29.6 0.8 -0.6 0.72 14.0 0.6 m -0.8 0.91 27.0 0.8 -0.6 0.67 6.2 0.6 *ca1 was excluded from the correlation analysis of the summer environmental monitoring data; b, slope; r2, correlation coefficient y = -0.8992x + 24.958 r² = 0.6713 y = -0.898x + 22.053 r² = 0.8227 y = -0.7574x + 22.435 r² = 0.6175 y = -0.8378x + 22.582 r² = 0.9148 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 15 18 20 23 25 28 30 33 35 tmin_out (°c) t m in _d = t m in _i nt m in _o ut (° c ) y = -0.8796x + 13.278 r² = 0.8923 y = -0.7556x + 7.3116 r² = 0.6741 y = -0.6351x + 8.8965 r² = 0.7185 y = -0.6031x + 3.7491 r² = 0.6652 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 0 3 5 8 10 13 15 18 20 tmin_out t m in _d = t m in _i nt m in _o ut (° c ) increasing warming effectincreasing cooling effecta b results of the regression analysis using the daily values of the minimum air temperature are given in table 7. it is shown that the minimum air temperatures (tmin) of the examined spaces present a good inverse correlation with the difference between the minimum indoor temperature and minimum ambient air temperature (tmin_d = tmin_in-tmin_out) during the summer period (table 7a). the higher the minimum outdoor temperature the stronger the cooling effect inside the examined spaces is. the cooling effect patterns appear more intense in partially subterranean spaces than in above-ground spaces, i.e. for every 1°c increase of outdoor minimum temperature the average cooling effect is estimated to be 0.9°c and 0.8°c for partially subterranean spaces and above-ground spaces, respectively. furthermore, the shift of the lines representing partially subterranean spaces below the lines of above-ground spaces indicates that lower minimum temperatures generally occur in the case of the former. during the winter period, minimum temperatures (tmin) inside the examined spaces are inversely correlated with the difference between minimum indoor temperature and minimum ambient air temperature (tmin_d). table 7b indicates that the warming effects of indoor spaces are strongly associated with colder days, i.e. with lower minimum temperatures. in addition, the warming effect of the aboveground spaces is found to be weaker than in partially subterranean rooms. based on the resulting regression, when the minimum outdoor temperature decreases by 1°c, the average warming effect enhances by 0.8–0.9°c for partially subterranean spaces and 0.6°c for above-ground spaces. indoor minimum temperatures in partially subterranean and above-ground spaces in coastal regions remain above outdoor minimum temperatures when outdoor minimum temperature is equal to, or lower than, 15.1°c and 14°c respectively. in the case of mountainous regions, these values are estimated to reach table 7. linear regression results for partially subterranean and above-ground spaces. regression is performed between tmin_in and tmin_d (tmin_in-tmin_out) summer winter b r² tmin_out lower limit in which tmin_d ≤ 0 cooling effect for every 1°c increase of tmin_out b r² tmin_out upper limit in which tmin_d ≥ 0 warming effect for every 1°c decrease of tmin_out partially subterranean spaces c* -0.9 0.67 27.8 0.9 -0.9 0.89 15.1 0.9 m -0.9 0.82 24.6 0.9 -0.8 0.67 9.7 0.8 reference above-ground spaces c -0.8 0.62 29.6 0.8 -0.6 0.72 14.0 0.6 m -0.8 0.91 27.0 0.8 -0.6 0.67 6.2 0.6 *ca1 was excluded from the correlation analysis of the summer environmental monitoring data; b, slope; r2, correlation coefficient y = -0.8992x + 24.958 r² = 0.6713 y = -0.898x + 22.053 r² = 0.8227 y = -0.7574x + 22.435 r² = 0.6175 y = -0.8378x + 22.582 r² = 0.9148 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 15 18 20 23 25 28 30 33 35 tmin_out (°c) t m in _d = t m in _i nt m in _o ut (° c ) y = -0.8796x + 13.278 r² = 0.8923 y = -0.7556x + 7.3116 r² = 0.6741 y = -0.6351x + 8.8965 r² = 0.7185 y = -0.6031x + 3.7491 r² = 0.6652 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 0 3 5 8 10 13 15 18 20 tmin_out t m in _d = t m in _i nt m in _o ut (° c ) increasing warming effectincreasing cooling effecta b summer winter b r² tmin_out lower limit in which tmin_d ≤ 0 cooling effect for every 1°c increase of tmin_out b r² tmin_out upper limit in which tmin_d ≥ 0 warming effect for every 1°c decrease of tmin_out partially subterranean spaces c* -0.9 0.67 27.8 0.9 -0.9 0.89 15.1 0.9 m -0.9 0.82 24.6 0.9 -0.8 0.67 9.7 0.8 reference above-ground spaces c -0.8 0.62 29.6 0.8 -0.6 0.72 14.0 0.6 m -0.8 0.91 27.0 0.8 -0.6 0.67 6.2 0.6 table 7 linear regression results for partially subterranean and above-ground spaces. regression is performed between tmin_in and tmin_d (tmin_intmin_out) *ca1 was excluded from the correlation analysis of the summer environmental monitoring data; b, slope; r2, correlation coefficient the environmental analysis presented in the current study indicates that partially subterranean spaces have a high environmental potential in the mediterranean climatic context. it is here demonstrated that during the summer period, in both the coastal and mountainous regions of cyprus, partially subterranean spaces cause a considerable dampening effect of the external thermal inflows. compared to above-ground reference spaces, partially subterranean spaces provide significantly lower temperatures, improving thermal comfort conditions. the better performance of partially subterranean spaces in terms of perceived air temperatures is attributed to the thermal mass of discussion 93 journal of sustainable architecture and civil engineering 2016/3/16 the earth which has the ability to further regulate indoor microclimate. additionally, the earth that surrounds partially subterranean structures is cooler during the hot period, compared to the ambient air to which above-ground spaces are exposed. this means that earth acts as a heat sink for cooling. the temperatures results obtained for the summer period in the present study are in line with the results reported in other previous studies (e.g. canas and martin 2005). in terms of humidity levels, partially subterranean spaces in mountainous regions were found to have the capacity of regulating indoor humidity within acceptable levels. in contrast, the spaces under study in the coastal region exhibit high humidity, which has a negative impact on comfort conditions. this may be attributed to the proximity to the sea, the poorly drained soil, as well as to the poor ventilation of indoor spaces. these results are in line with findings reported in other studies (meir and gilead 2002; canas and martin 2005). the environmental limitations resulting from high humidity might explain why traditional partially subterranean spaces rarely appear in humid climates as stated in related literature (zhai and previtali 2010). the enhancement of air movement through natural ventilation constitutes a passive design strategy, which could significantly minimize dampness. moreover, the architectural design of traditional dwellings i.e. the shallow plan layouts and wide façades, as well as the double-sided window arrangement, which form typical characteristics of vernacular architecture in coastal regions of cyprus, offer potentials for sufficient natural ventilation. the onsite monitoring results during the winter period show that the thermal comfort conditions of partially subterranean spaces, in both coastal and mountainous regions, are unsatisfactory. several reasons could explain the low temperatures observed within these spaces. for instance, the thick, high mass building envelopes, and the small and limited window openings, block solar penetration, which would allow passive heating. however, despite their insufficient performance, partially subterranean spaces exhibit higher temperatures than those of the above-ground spaces confirming the positive contribution of high thermal inertia and insulating properties of the earth. the earth mass, that is warmer in winter than ambient air, serves as a passive source for heating. humidity levels prove to be high above acceptable limits in both coastal and mountainous regions. the relative rise of outdoor humidity during the winter period, as in the case of mountainous regions, may have resulted in increased dampness in the indoor spaces under study. the regression results obtained for the partially subterranean spaces under examination highlight their stronger cooling and warming effect patterns in the summer and winter respectively, compared to above-ground spaces. more specifically, the analysis reveals that when the outdoor temperature during the summer becomes higher, the cooling effect becomes stronger. similarly, when the outdoor temperature during the winter becomes lower, the warming effect becomes stronger. this interrelation has also been reported by givoni (1998), shaviv et al. (2001) and ogoli (2003) in high mass indoor spaces and by tsiros and hoffman (2014) in semi-outdoor spaces during the summer period. this confirms that maximum control over outdoor temperature extremes may be achieved through the incorporation of subterranean rooms. research results also indicate that the surface area of the building envelope in contact to the soil affects indoor thermal conditions; the greater the contact of the building envelope with soil, the greater the potential for moderation of outdoor temperature extremes in the indoor space. the assessment of thermal performance of the spaces under study was obtained using air temperature and relative humidity recordings. wind speed and mean radiant temperature were not recorded during the experimental period. this limitation does not permit the calculation of operative temperature and by extension, the evaluation of human thermal comfort conditions in the indoor spaces under study. journal of sustainable architecture and civil engineering 2016/3/16 94 in an attempt to explore partially subterranean spaces in terms of their thermal behaviour in diverse climatic contexts, onsite air temperature and relative humidity measurements were carried out. it is presented herein that in different climatic regions of cyprus that lay in a relatively small geographical area, partially subterranean spaces present different thermal behaviour. this highlights that partially subterranean spaces cannot be treated in a uniform manner in different contexts since, a number of varying parameters, such as the local climate, local soil properties, the architectural layout, the openings arrangement and natural ventilation conditions form determining factors of the spaces’ actual thermal performance. concerning the air temperature recordings, partially subterranean spaces were found to function as positive climatic elements in the mediterranean climate of cyprus during summer. mean reductions in indoor maximum temperatures compared to the ambient environment were found to reach up to 3.0°c in the coastal and 3.9°c in the mountainous regions. in contrast to partially subterranean spaces in the mountainous region, relative humidity in the coastal region exceeded the acceptable 70% upper limit threshold for a large part of the monitoring period. this creates uncomfortable conditions which result to unhealthy effects for the occupants. the winter performance of partially subterranean spaces proved to be the most challenging one. mean maximum temperatures inside these spaces remain up to 1.5°c and 1.3°c lower than the outdoor temperature maxima in the coastal and mountainous regions respectively. however, it is worth noting that, partially subterranean spaces exhibit higher temperatures compared to above-ground spaces. in terms of humidity levels, partially subterranean spaces in both regions suffer from humid indoor conditions. in conclusion, the current study provides a basis for the formulation of a site-specific design strategy to improve thermal conditions and achieve energy conservation within subterranean constructions in diverse geographical locations. understanding and analysing the thermal behaviour of these spaces is the first step towards this strategy. the quantitative analysis reveals the various challenges faced and opportunities provided by subterranean structures and contributes to informing current design policies. further studies should focus on the effects of other parameters on thermal comfort, such as the wind speed and mean radiant temperature. this would allow a precise evaluation of the thermal comfort conditions inside partially subterranean spaces by using established indoor environmental indices and standards. the work described in this paper is based on the findings of a research program entitled “implementation of sustainable design elements of vernacular architecture in the rehabilitation of traditional buildings and in the design of new structures” funded by a university of cyprus institutional grant (reference number 8037p-3/311-54010) and covering the period of july 2013 to july 2015. acknowledgment al-temeemi, a. & harris, d., 2004. a guideline for assessing the suitability of earth-sheltered mass-housing in hot-arid climates. energy and buildings, 36(3), pp. 251-260. https:/doi.org/10.1016/j.enbuild.2003.12.005 canas guerrero, i. & martin ocana, s., 2005. study of the thermal behaviour of traditional wine cellars: the case of the area of “tierras sorianas del cid” (spain). renewable energy, 30(1), pp. 43-55. https:/doi.org/10.1016/j.renene.2004.04.014 enlart, c., 1987. gothic art and the renaissance in cyprus. london: trigraph, a.g. leventis. florides, g., tassou, s., kalogirou, s. & wrobel, l., 2001. evolution of domestic dwellings in cyprus and energy analysis. renewable energy, 23(2), pp. 219-234. https:/doi.org/10.1016/s0960-1481(00)00160-9 givoni, b., 1998. climate considerations in building and urban design. newyork: wiley. hadjisavvas, s., 2012. excavating the tombs of the kings. a wornd heritage site. nicosia: napaphos. conclusions references 95 journal of sustainable architecture and civil engineering 2016/3/16 kharrufa, s. n., 2008. evaluation of basement’s thermal performance in iraq for summer use. asian architecture and building engineering, 7(2), pp. 411-417. https:/doi.org/10.3130/jaabe.7.411 kizildere, m. & ozsoy, e., 1995. lapithos. in: twelve traditional cyprus houses. nicosia: unhcr, pp. 148-157. lapithis, p., 2004. traditional vs contemporary vs solar buildings. freiburg, germany, s.n. malaktou, e., philokyprou, m., michael, a. & savvides, a., 2015. architectural design and environmental behavior of traditional buildings in mountainous regions. the case of askas settlement, cyprus. limassol, s.n. meir, i. & gilead, i., 2002. underground dwellings and their microclimate under arid conditions. toulouse, s.n., pp. 618-623. michael, a., heracleous, c., thravalou, s. & philokyprou, m., 2015. lighting performance of urban vernacular architecture in the east-mediterranean area: field study and simulation analysis. indoor and built environment, pp. 1-17. https:/doi. org/10.1177/1420326x15621613 michael, a., philokyprou, m., thravalou, s. & ioannou, i., 2013. contribution of bioclimatic elements to thermal comfort: heritage case study in nicosia, cyprus. munich, germany, s.n. michael, a., philokyprou, m. & argyrou, c., 2014. documentation and evaluation of the positive contribution of natural ventilation in the rural vernacular architecture of cyprus. limassol, springer. https:/doi.org/10.1007/978-3-319-13695-0_30 ogoli, d. m., 2003. predicting indoor temperatures in closed buildings with high thermal mass. energy and buildings, 35(9), pp. 851-862. https:/doi. org/10.1016/s0378-7788(02)00246-3 philokyprou, m., 1998. construction materials and structures in cypriot architecture: from the neolithic to the late bronze age. nicosia: unpublished phd thesis. philokyprou, m., michael, a., 2012, evaluation of the environmental features of vernacular architecture. a case study in cyprus. international journal of heritage in the digital era, pp. 349-354. philokyprou, m., michael, a., savvides, a. & malaktou, e., 2015. evaluation of bioclimatic design features of vernacular architecture in cyprus. case studies from rural settlements in different climatic regions. porto, green lines institute for sustainable development, pp. 999-1008. philokyprou, m., michael, a., thravalou, s. & ioannou, i., 2013. evaluation of sustainable design elements in the historic centre of nicosia, cyprus. villa nova de cerveira, taylor and francis. savvides, a., michael, a., malaktou, e. & philokyprou, m., 2016. examination and assessment of insolation conditions of streetscapes of traditional settlements in the eastern mediterranean area. habitat international, pp. 442-452. https:/doi. org/10.1016/j.habitatint.2015.12.002 serghides, d., 2010. the wisdom of mediterranean traditional architecture versus contemporary architecture-the energy challenge. the open construction and building technology journal, volume 12, pp. 29-38. https:/doi. org/10.2174/1874836801004010029 shaviv, e., yezioro, a. & capeluto, i. g., 2001. thermal mass and night ventilation as passive cooling design strategy. renewable energy, 24(34), pp. 445-452. https:/doi.org/10.1016/s09601481(01)00027-1 thravalou , s., philokyprou , m., michael , a. & savvides , a., 2015. the role of semi-open spaces as thermal environment modifiers in vernacular architecture of cyprus. limassol, s.n. tsiros, i. x. & hoffman, m. e., 2014. thermal and comfort conditions in a semi-enclosed rear wooded garden and its adjacent semi-open spaces in a mediterranean climate (athens) during summer. architectural science review, 57(1), pp. 63-82. https:/doi.org/10.1080/00038628.2013.829021 vegas, f., mileto, c., cristini, v. & checa, j. r. r., 2014. underground settlements. in: versus: heritage for tomorrow. vernacular knowledge for sustainable architecture. florence: firenze university press, pp. 115-127. wright, g., 1992. ancient building in cyprus. s.l.: brill academic pub. zhai, z. & previtali, j., 2010. ancient vernacular architecture: characteristics categorization and energy performance evaluation. energy and buildings, 42(3), pp. 357-365. https:/doi.org/10.1016/j. enbuild.2009.10.002 journal of sustainable architecture and civil engineering 2016/3/16 96 maria philokyprou assistant professor university of cyprus, department of architecture main research area architectural conservation, vernacular architecture, traditional building materials, sustainability, environmental aspects of vernacular architecture address 75 kallipoleos street, 1678, nicosia tel. + 357 22 892974 e-mail: mphiloky@ucy.ac.cy aimilios michael lecturer university of cyprus, department of architecture main research area energy and environmental design of buildings, sustainability and construction design, innovative and sustainable construction components and materials address 75 kallipoleos street, 1678, nicosia tel. + 357 22 892974 tel. + 357 22 892977 e-mail: aimilios@ucy.ac.cy andreas savvides assistant professor university of cyprus, department of architecture main research area sustainable urban design, environmental design of outdoor spaces, solar planning, community development address 75 kallipoleos street, 1678, nicosia tel. + 357 22 892974 tel. + 357 22 892967 e-mail: als@ucy.ac.cy eleni malaktou research associate university of cyprus, department of architecture main research area indoor and outdoor microclimate monitoring and assessment, energy efficient refurbishment of existing buildings, bioclimatic design address 75 kallipoleos street, 1678, nicosia tel. + 357 22 892974 tel. + 357 22 895412 e-mail: meleni@ucy.ac.cy about the authors journal of sustainable architecture and civil engineering 2015/2/11 52 jsace 2/11 journal of sustainable architecture and civil engineering vol. 2 / no. 11 / 2015 pp. 52-58 doi 10.5755/j01.sace.11.2.12430 © kaunas university of technology cement hydration with ultrasound treated clinoptilolite received 2015/03/03 accepted after revision 2015/06/01 cement hydration with ultrasound treated clinoptilolite vytautas sasnauskas*, gediminas rinkevičius, deividas martinavičius, danutė vaičiukynienė, ernestas ivanauskas kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania aras kantautas kaunas university of technology, faculty of chemical tecnology radvilenu st. 19, lt-50254 kaunas, lithuania there are many cement replacement materials and one of them is zeolites. zeolites are crystalline solids structures made of silicon, aluminum and oxygen that form a framework with cavities and channels inside where cations, water and/or small molecules may reside. in this study natural zeolite clinoptilolite was used. clinoptilolite is the most popular natural zeolite mineral with the chemical formula (na, k, ca) 23 al 3 (al,si) 2 si 13 o36·12h 2 o. the present paper shows the results of using ultrasound treated clinoptilolite as portland cement replacement material. the duration of ultrasound treatment was 5 min, 10 min, and 20 min. results showed that the xrd of ultrasound-treated clinoptilolite slightly differs in comparison to conventional clinoptilolite. the cement samples with 5% and 10% clinoptilolite substitute provide the strength increase, 30% significantly reduces the strength compared to control samples. the heat measurements of portland cement paste hydration, containing clinoptilolite, showed that the clinoptilolite slightly increases the duration of hydration, but hydration temperature is lower than in the controls samples. the experimental results suggest that ultrasound-treated clinoptilolite positively influence cement hydration processes, consolidation kinetics, csh formation; the mechanical strength of the samples is increased. typical content of portland cement substituting does not exceed 20% of mass of portland cement in samples. reducing the consumption of portland cement with substituting it with ultrasound treated clinoptilolite is preferred for reasons of environmental protection. keywords: cement hydration, clinoptilolite, ultrasound, zeolite. *corresponding author: vytautas.sasnauskas@ktu.lt http://dx.doi.org/10.5755/j01.sace.11.2.12430 introduction pressure increase changes with pressure decrease in half-wave of the liquid phase during ultrasonic waves’ propagation in liquids. the pressure pulsation amplitude becomes quite large and quickly growing the gas vapor mixture filled bubbles begin to form in pressure decrease areas in the liquid at high energy intensity (> 2.5 w/cm2). the bubble volume decreases very quickly and they collapse at pressure increase phase. this phenomenon is called cavitation. shock wave forms in bubble collapse place. it is possible to observe the whole range of physical chemical phenomena, if bubbles’ collapsation intensively takes place in liquid. physical chemical phenomena are: solid surface destruction (if aluminum foil will be placed to acoustic cleaner, so after a few minutes the holes will appear, and even after a while it will be completely destroyed in the smallest particles), mixing of immis53 journal of sustainable architecture and civil engineering 2015/2/11 cible liquids (e.g., oil with water), acoustic cavitation, intensive mixing, solid and liquid material dispersion, polymerization or depolymerization reactions under certain conditions, and a number of other phenomena. reduction of carbon dioxide emissions into the environment is currently one of the most important objectives in cement industry, and at the same time in construction industry. more production and use of cements with a part of clinker, replaced by mineral additives, i.e., limestone, pozzolan, slag, zeolite, etc. are the main means of this problem solving. clinoptilolite is the most common natural zeolite mineral with the chemical formula (na, k, ca) 2-3 al 3 (al,si) 2 si 13 o 36 •12h 2 o (brek, 1976). application of ultrasound can influence the size and morphology of the crystals, crystallization time and the crystallinity of the zeolites (askari et. al., 2013). (yeong et. al., 2014) showed that the crystallization time was reduced by introducing ultrasonic pre-treatment from 7 days to 3 days, without affecting the structure, morphology and co 2 adsorption capacity of the resulting zeolite-t. (solyman et. al., 2013) revealed that sonication of parent zeolite samples affects unit cell dimensions and their crystal size. ftir-spectroscopic analysis indicated that sonication may decrease the pore opening and cause framework structure defects. tem and sem micrographs showed that sonication broke-up and re-ordered zeolite crystals with longer time resulted in a different morphology relative to parents and also change the particle size. nap zeolite nano crystals were synthesized by sonochemical method at room temperature with 3 h of crystallization time. the effect of ultrasonic energy and irradiation time showed that the crystallinity of the powders decreased with increasing sonication energy, but phase purity remained unchanged. sonication energy facilitates the formation of active radicals which are responsible for rapid crystallization of zeolite phase (pal et. al., 2013). clinoptilolite may be used as pozzolan due to its reactive sio 2 content and ion exchange properties. strength development and other properties of cements depending on the percentage of zeolite blend ratios were researched and the results were found positive in scientific studies performed on the usability of natural zeolite as cement blend material (yılmaz et. al., 2007). the use of clinoptilolite in the mortars increases the strength values. clinoptilolite replacement decreases water absorption and porosity of the mortars. clinoptilolite incorporated mortars show better durability than of the control mortar. the exploitation of clinoptilolite can lead to a considerable economic benefit (bilim, 2011). the evolution of phase contents showed that the addition of natural zeolites accelerates the onset of c 3 s hydration and precipitation of ch and aft. kinetic analysis of the consumption of c 3 s indicates that the enveloping of c–s–h layer is thinner and/or less dense in the presence of alkali-exchanged clinoptilolite pozzolans. the zeolite pozzolanic activity is interpreted to depend on the zeolite exchangeable cation content and on the crystallinity. the addition of natural zeolites alters the structural evolution of the c–s–h product. longer silicate chains and lower c/s ratio are deduced from the evolution of the c–s–h b-cell parametre (snellings et. al., 2010). the most significant effects are in reduction in chloride permeability, a significant reduction in expansion due to alkali-aggregate reaction, and an improved resistance to acid and sulfate attacks, all of them are related to the overall densification of the microstructure, alkali-binding capacity of zeolite-blended cement pastes, and pozzolanic consumption of calcium hydroxide component of portland cement hydration in the paste (jana, 2007). utilization of mineral additives in concrete increases the durability of concrete. the mechanical and physical properties of concrete improve the usage of zeolite, fly ash and ground granulated blast furnace slag. ettringite and asr gel formation in the microstructure of the composite against journal of sustainable architecture and civil engineering 2015/2/11 54 methods results and discussions sulfate attack was limited with the usage of zeolite, fly ash and ground granulated blast furnace slag (karakurt, topçu, 2011). blended cements containing high volume of natural zeolite were studied there. hydration characteristics and paste microstructure were investigated also. no free ca(oh) 2 in pastes at the end of 28 days of hydration was observed. crystal structure of zeolite completely decomposed at the end of 28 days. similar 28-day compressive strength to that of reference portland cement was found (uzal, turanlı, 2012). hydration heat development in blended cements containing natural zeolite was analyzed. natural zeolite accelerates the onset of c 3 s hydration and boosts the first phase of c 3 a hydration. the second phase of c 3 a hydration gains on importance with the increasing zeolite dosage. effectiveness of natural zeolite as a binder decreases with the increasing dosage when its content is higher than 10% (tydlitát, zákoutský, černý, 2014). modified zeolite additive increases the compressive strength. it is related to active sio 2 and al 2 o 3 present in the modified zeolite (vaičiukynienė et. al., 2013). the aim of this research is to determine the influence of ultrasound treated clinoptilolite on cement hydration. a portland cement of cem i 52.5r type with a blaine surface specific area of 370 m2/kg, its mineral composition: c 3 s = 50.7 %; c 2 s = 18.5 %; c 4 af = 14.2 %; c 3 a = 9.7 %, initial binding of 130 min, finish after 215 min, bending length after 28 days of 8,1 mpa, compressive strength of 57,6 mpa was used for all mixes. physical properties of investigated clinoptilolite are: bulk density is 2370 kg/m3, specific surface is 144 m2/g, purity is not less than 90%. chemical composition: sio 2 =(71.5%), al 2 o 3 =13.1%, fe 2 o 3 =0.9%, tio 2 =0.2%, cao =2.1%, mgo =1.07%, p 2 o 5 =0.033%, k 2 o+na 2 o =5.03%, f =0.025%. the x-ray powder diffraction data was collected by a dron-6 x-ray diffractometer with bragg-brentano geometry using ni-filtered cu kα radiation and graphite monochromator, operating with the voltage of 30 kv and emission current of 20 ma. the step-scan covered the angular range of 2°70° in steps of 2 = 0.02°. specific powder surface was measured by blaine method (en 196-6:2010). the cement paste hydration temperature measurements were performed with 8-channel usb tc-08 thermocouple data logger (temperature measurement range from -270 to +1820 °c). ultrasonic treatment was carried out by bandelin electronic uw3400 device with 200 w of power. particle size distribution and specific surface area were determined by “mastersizer 2000” instrument from malvern. red light was produced by helium-neon laser and blue light was obtained from a solid phase source. sample constant flow was steady and the ratio of water and solid material was constant and equal to w/s = 0.35 during all test. the compositions differed by the contents of z0, z1 or z2: 0%, 5%, 10%, 20% and 30% mass. formed test samples were hardened for 28 days and 90 days. the test procedure of hardened cement paste compressive strength was applied according to the en 196-1. toni technik 2020 press was used to determine mechanical characteristics of the samples. clinoptilolite was used as a substitute for cement; it contains heulandite and quartz in addition to the basic mineral clinoptilolite (fig. 1). zeolite water suspension was ultrasonically treated for 0, 5 min, 10 min and 20 min. it was determined that increased 1,000 nm peak after the dispersion is characteristic to heulandite and decreased 0.316 nm peak is attributed to clinoptilolite (fig.1.). 55 journal of sustainable architecture and civil engineering 2015/2/11 the results of granulometric analysis showed that the particle size of the clinoptilolite depends on the ultrasound processing time (fig. 2). most predominant (90 %) particle size of untreated clinoptilolite is 277.8 mm and specifi c surface was 5744 cm2/g, then aft er 5 minutes of ultrasonic treatment their size was 221.8 mm, 137.9 mm size was obtained aft er 10 min and 152.0 mm size was obtained aft er 20 minutes. specifi c surface of clinoptilolite particles aft er 5 min of ultrasonic treatment has decreased from 5745 cm2/g to 5324 cm2/g, and specifi c surface particles increased aft er longer time of their ultrasound treatment, respectively, aft er 10 min and 20 min to fig. 1 x-ray diffraction patterns of ultrasonically treated clinoptilolite. treatment time: 1) 0 min, 2) 5 min, 3) 10 min and 4) 20 min. notes: cl is clinoptilolite, h is heulandite, and q is quartz fig. 2 clinoptilolite particle size distribution histograms. ultrasonically untreated clinoptilolite (a), processed by ultrasound clinoptilolite: for 5 min (b), for 10 min (c) and for 20 min (d) a c d b journal of sustainable architecture and civil engineering 2015/2/11 56 6090 cm2/g and 6817 cm2/g. thus, particles get smaller when the ultrasonic processing time is increased up to 20 minutes, specifi c surface increases, but specifi c surface decreases aft er 5 min of clinoptilolite ultrasound treatment. it is likely that the polymerization and depolymerization reactions occurred in the cavitation fl uid aft er 5 minutes. cement paste samples were prepared for further investigation where a part of portland cement was replaced by clinoptilolite. the hydration of the paste was investigated: cement paste hydrafig. 3 hydration temperature kinetic curves of cement paste with 5 and 10% ultrasound treated clinoptilolite. ultrasaoun treated duration: 5 and 20 min fig. 4 x-ray diffraction patterns of hardened cement paste after 28 days. clinoptilolite content accounts for 20 %: reference sample (1); clinoptilolite without sonication (2); clinoptilolite 5 min sonicated (3); clinoptilolite 10 min sonicated (4); clinoptilolite 20 min sonicated (5); notes: ch – portlandite; a – alite; k – calcium silicate hydrate; d belite; c – clinoplolite; e – ettringite tion temperatures and time were determined (fig. 3). the maximum hydration temperature (85 °c) was of the control sample, i.e., the sample without clinoptilolite. hydration peaks decreases using clinoptilolite as a replacement for portland cement, i.e., their temperature is 79.8 °c and 79.4 °c using 5%, and 74.3 °c and 72.9 °c with a 10% of portland cement replacement. hydration duration time using clinoptilolite decreases from 417 min to 383 min and 389 min respectively using 5% and 10% clinoptilolite substitute. comparing the cement paste samples with ultrasound-treated and untreated clinoptilolite it can be said that the additive ultrasonic treatment because of its higher specifi c surface slightly reduces the duration of hydration peaks. x-ray diff raction analysis results of the hydrated samples (fig. 4) show calcium silicate hydrate, alite, belite and portlandite, as well as small amount of ettringite dominated in the hardened cement paste with and without supplementary cement material. not all zeolite content completely reacts having replaced 20% of portland cement by clinoptilolite, and part of it remains as a fi ller in cement stone (fig. 4a). the main portlandite peak (0.493 nm) intensity decrease (fig. 4 b) can be seen in a cross-reference of control sample with samples where a part of portland cement is changed by clinoptilolite. this may be related to clinoptilolite pozzolanity and the portland cement amount reduction in the mixture. clinoptilolite substitute of 5% and 10% in the samples increases their strength, and then subsequently decreases, but remains still close to the strength of the control sample (fig. 5). 11.5% a b 57 journal of sustainable architecture and civil engineering 2015/2/11 and 8.7% increase in strength is obtained after treatment of clinoptilolite by ultrasound for 10 min and 20 min respectively, using 5% of clinoptilolite and comparing to the samples with 5% of untreated by ultrasound clinoptilolite. similar sample strength dependence is during both after 28 days and after longer hardening duration of 90 days. this allows the use of ultrasound-treated clinoptilolite additive in cementitious samples respectively over a wide range. by treated clinoptilolite with ultrasound for 5 minutes, it was determined that no significant effect on samples mechanical physical properties found. increasing the ultrasonic treatment duration it was observed that the compressive strength of samples increases. this is related to the treated clinoptilolite surface morphology and specific surface characteristics change. the optimal duration of clinoptilolite a b fig. 5 the compressive strength after 28 days (a) and 90 days (b) of cement stone with 0, 5, 10, 20 and 30% of clinoptilolite, treated by ultrasound for 0, 5 min, 10 min and 20 min treatment was 10 min. after 28 days of hydration the highest compression strength was for samples, forming with 5 % clinoptilolite, which was ultrasaound treated 10 min. the research of ultrasound treated clinoptilolite has shown that it can be used in concrete technology as portland cement substitute. physical mechanical researches with ultrasound-treated clinoptilolite in portland cement paste showed that the compressive strength of the samples increased significantly compared with untreated clinoptilolite additive. ultrasonically treated clinoptilolite additive in concrete technology allows using it in concrete mixtures for special use areas, such as: aggressive waste storage container industry, thus solving relevant ecological problems. conclusions brek., d. zeolite molecular sieves. moscow: mir; 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29th icma conference on cement microscopy. quebec city: curran associates inc.; 2007; : 168–206. karakurt, c., topçu, i̇.b. effect of blended cements produced with natural zeolite and industrial byproducts on alkali-silica reaction and sulfate resistance of concrete. construction and building materials, 2011; 25(4): 1789-1795. http://dx.doi. org/10.1016/j.conbuildmat.2010.11.087 uzal, b., turanlı, l. blended cements containing high volume of natural zeolites: properties, hydration and paste microstructure. cement and concrete composites, 2012; 34(1): 101-109. http:// dx.doi.org/10.1016/j.cemconcomp.2011.08.009 tydlitát, v., zákoutský, j., černý, r. early-stage hydration heat development in blended cements containing natural zeolite studied by isothermal calorimetry. thermochimica acta, 2014; 582: 5358. http://dx.doi.org/10.1016/j.tca.2014.03.003 vaičiukynienė, d., skripkiūnas, g., daukšys, m., sasnauskas, v. cement hydration with zeolitebased additive. chemija, 2013; 24(4): 271-278. vytautas sasnauskas assoc. professor kaunas university of technology, faculty of civil engineering and architecture main research area building materials address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300465 e-mail: vytautas.sasnauskas@ktu.lt gediminas rinkevičius student kaunas university of technology, faculty of civil engineering and architecture main research area building materials address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300465 e-mail: gediminas.rinkevicius@ktu.edu deividas martinavičius student kaunas university of technology, faculty of civil engineering and architecture main research area building materials address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300465 e-mail: deividas.martinavicius@ktu.edu about the authors danutė vaičiukynienė professor kaunas university of technology, faculty of civil engineering and architecture main research area building materials address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300465 e-mail: danute.palubinskaite@ktu.lt aras kantautas assoc. professor kaunas university of technology, faculty of chemical tecnology main research area building materials address radvilenu st. 19, lt-50254 kaunas, lithuania tel. +370 37 300163 e-mail: aras.kantautas@ktu.lt ernestas ivanauskas assoc. professor kaunas university of technology, faculty of civil engineering and architecture main research area building materials address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300465 e-mail: ernestas.ivanauskas@ktu.lt journal of sustainable architecture and civil engineering 2018/1/22 64 *corresponding author: k.paulius@yahoo.com research on installation technologies of corrosion protection for steel structures received 2018/04/07 accepted after revision 2018/06/21 journal of sustainable architecture and civil engineering vol. 1 / no. 22 / 2018 pp. 64-75 doi 10.5755/j01.sace.22.1.20902 © kaunas university of technology research on installation technologies of corrosion protection for steel structures jsace 1/22 http://dx.doi.org/10.5755/j01.sace.22.1.20902 paulius kavaliauskas*, mindaugas daukšys kaunas university of technology, faculty of civil engineering and architecture, studentų str. 48, lt-51367 kaunas, lithuania introduction rusted s275 steel profiles were used in the experimentation. according to standard iso 8501-1 the steel rust grade b. the steel was cut into nine samples with dimensions 150×150 mm and brought into three groups with three samples in each group. in each group the surface for anticorrosive coating of specimen was prepared in three different methods. the steel surface was sandblasted using quartz sand with fraction 0-0.8 mm. using this method, the preparation level of surface sa 3 according to standard 8503-1 was achieved. the specimen in second group were prepared by mechanical method using the wiry brush. the level of surface st 2 was achieved according to standard iso 8503-1. in third group the specimen were not prepared in any method. according to the standard iso 12944-5:2007 three different anticorrosive coating systems were selected: one component alkyd paint system, two component epoxy and polyurethane paint system and two component zinc, epoxy and polyurethane paint system. the paint systems were selected considering the category of corrosion c3 and c4. the coating of paint systems was performed using the airless painting equipment. the thickness of each layer, wet and dry, were controlled. the thickness results of dry coating were measured with digital device “positector”. to accelerate the process of corrosion, the aggressive artificial atmosphere was created according to the standard iso 9227:2017 corrosion tests in artificial atmospheres – salt spray tests. neutral salt spray test is the method in which 5 % neutral sodium chloride melting is automated in controlled environment. the sufficient amount of sodium chloride is dissolved in distilled water with specific conduction not exceeding the 20 µs/cm at 25 ± 2°c to get the concentration of 50 ± 5 g/l. the steel samples were kept in artificial atmosphere for 500 hours. anticorrosive coating characteristics for differently prepared surfaces were analysed by testing the adhesion according the standard iso 4624:2016 using digital adhesion gauge “elcometer 506”. keywords: preparation level of steel surface, steel protection from corrosion, painting systems, salt spray test, adhesion test. oil recycling, petrol, chemistry, ships, food and other industrial objects metal constructions often are affected by extremely aggressive atmosphere. strict anticorrosive safety requirements are applicable to these constructions. financially it is very important to protect the products from corrosion. the durability of a product will be prolonged, the maintenance expenses reduced and the risk of accidents lowered, which can affect the people and the atmosphere. in some cases it is difficult to define what is a protection and what is a cosmetic. nice-looking buildings are usually well maintained. for some structures the cosmetic is unnecessary and for others – conversely, for example, the appearance for cruisers is very important. nowadays, the building constructions becoming larger and more complex, construction companies have to expeditiously plan consumption of their materials, the speed of works and the use of 65 journal of sustainable architecture and civil engineering 2018/1/22 innovative technologies. constructive and technological solutions, clarity of clients’ expectations, time, choosing the right materials, project management, investment are the most important things which determine the profit. roselli et al. 2013 analysed the role of aluminium phosphosilicate in painting rusted steel. the aim of this investigation was to employ a wash-primer to accomplish the chemical conversion of rusted surface when current cleaning operations were difficult to carry out. the active component of wash-primer was aluminium phosphosilicate. primed rusted steel panels were coated with an alkyd system to perform accelerated tests in the salt spray chamber and electrochemical impedance measurements. tests were conducted in parallel with a chromate wash-primer and the same alkyd system. results showed that the wash-primer containing aluminium phosphosilicate could be used satisfactory to paint rusted steel exhibiting a similar performance to chromate primer. carpen, 2008 in her research report of stainless steel used in fire protection systems analysed two failure cases in fire protection systems, one in stainless steel factory and one in power plant have been studied. most of corrosion damages are associated on the weld nuggets or in the heat-affected zones of girth site welds. one of the most important factors affecting the corrosion resistance of stainless steel at welds and in heat-affected zones are the surface oxide films originating from the welding heat in the presence oxygen. proper root shielding is important where the water is taken from natural sources, as microbially inducted corrosion can increase the risk for corrosion damage significantly. melchers, 2006 studied modelling immersion corrosion of structural steels in natural and brackish waters. the multi-phase mean-value model previously proposed for modelling the marine immersion corrosion of low carbon and low alloy structural steels were examined for application to fresh and brackish waters. corrosion in brackish and fresh waters corrosion depends on water hardness, ph and nutrient levels, with higher ph levels and lower water hardness associated with higher anaerobic levels of corrosion but these are not significant for anaerobic corrosion. hoeke et al. 2009 analysed the degradation of steel girder bridge bearing systems by corrosion. corrosion of anchor bolts in bridge bearings presents two principal problems: (1) failure of the anchorage due to loss of bolt shear strength, and (2) loss of bearing functionality due to the build up of corrosion products. field investigations were performed at eight bridges around georgia. anchor bolt corrosion was found to be locally accelerated, with necking occurring at the concrete interface. this degradation is primarily due to the formation of concentration cells with the alkaline concrete embedment and to crevice effects where the build up of soil and debris occurs at the anchorage. an experimental program was developed, including long-term in-solution exposures in addition to electrochemical testing. results of long-term concentration cell experiments indicate corrosion rates up to 4.5mpy, 4 to 6 times that of the same bolt anchor in an uncoupled state. type 304, 316, 2101, and 2205 candidate stainless steels were investigated using cyclic polarization. each alloy showed adequate corrosion resistance in the simulated bridge bearing environment, with type 304 showing the least resistant to localized corrosion. ramezanzadeh et. al. 2016 investigated the enhancement of barrier and corrosion protection performance of an epoxy coating through wet transfer of amino functionalized graphene oxide (fgo). an amino functionalized graphene oxide was synthesized and characterized by fourier transform infrared spectroscopy and x-ray diffraction analysis. then, fgo/epoxy composite was prepared through dispersing 0.1 wt.% of fgo oxide in an epoxy coating through wet transfer method. the go/epoxy and fgo/epoxy composites were applied on the mild steel substrates and their barrier and corrosion protection performance were characterized by salt spray test and electrochemical impedance spectroscopy. incorporation of 0.1 wt.% of fgo nanosheet into the epoxy coating significantly enhanced the corrosion resistance of the coating through improving its ionic resistance as well as barrier properties. journal of sustainable architecture and civil engineering 2018/1/22 66 ulaeto et. al. 2017 investigated the progress in organic coatings. smart coatings are innovative coatings that can react spontaneously, due to inbuilt stimuli-responsive mechanisms. the functionality obtained from these class of coatings at the metal-solution interface in aggressive environments has led to advances in anticorrosion studies and applications. the smart coatings respond to single/multiple external stimuli such as light, dirt, ph changes, temperature, aggressive liquids, bio-foulant, impact, fatigue etc.; and have demonstrated outstanding, barrier properties with scratch resistance, in-situ healing, high optical transmission, thermal stability, and resistance to strong acids etc. according to authors studies the conclusion was made that appropriately unprotected steel structures and mechanisms are affected by corrosion, steel structures lose their strength and the time of exploitation is significantly reduced. one of the most dangerous zones for corrosion is welding seams. in these science publications origin of corrosion grounds, determination of corrosion failures, innovative technologies of smart coating systems and the effect of different environment were analysed. the aim of this work – to analyse the steel constructions’ protection from corrosion installation technologies and to investigate how the level of surface preparation influence the anticorrosive coat characteristics. the steel protection from corrosion using different painting systems and different ways of preparation the surface of steel was analysed. in the research it was seeking to reveal the main advantages and disadvantages comparing different technologies and how the steel surface prepared in different ways can affect the anticorrosive coat characteristics. fig. 1 according to iso 8501-1 the primary condition of steel was determined as rust grade b in the research, the chosen rusted steel samples were cut into nine samples with dimensions 150×150 mm and brought into three groups with three samples in each group. according to standard iso 8501-1, the primary condition of steel was determined as rust grade b (see fig. 1). methods according to authors studies the conclusion was made that appropriately unprotected steel structures and mechanisms are affected by corrosion, steel structures lose their strength and the time of exploitation is significantly reduced. one of the most dangerous zones for corrosion is welding seams. in these science publications origin of corrosion grounds, determination of corrosion failures, innovative technologies of smart coating systems and the effect of different environment were analysed. the aim of this work – to analyse the steel constructions’ protection from corrosion installation technologies and to investigate how the level of surface preparation influence the anticorrosive coat characteristics. the steel protection from corrosion using different painting systems and different ways of preparation the surface of steel was analysed. in the research it was seeking to reveal the main advantages and disadvantages comparing different technologies and how the steel surface prepared in different ways can affect the anticorrosive coat characteristics. methods in the research, the chosen rusted steel samples were cut into nine samples with dimensions 150×150 mm and brought into three groups with three samples in each group. according to standard iso 85011, the primary condition of steel was determined as rust grade b (see figure 1). figure 1. according to iso 8501-1 the primary condition of steel was determined as rust grade b in each group the surfaces of specimen were prepared in different ways for the applying the anticorrosive protection. three different preparation methods were selected:  the surface of corroded steel specimen was processed by sand blasting according to the standard iso 8501-1. quartz sand with fraction 0-0.8 mm. was used in the process. the level of surface sa 3 according to standard 8503-1 was achieved and presented in figure 2. according to authors studies the conclusion was made that appropriately unprotected steel structures and mechanisms are affected by corrosion, steel structures lose their strength and the time of exploitation is significantly reduced. one of the most dangerous zones for corrosion is welding seams. in these science publications origin of corrosion grounds, determination of corrosion failures, innovative technologies of smart coating systems and the effect of different environment were analysed. the aim of this work – to analyse the steel constructions’ protection from corrosion installation technologies and to investigate how the level of surface preparation influence the anticorrosive coat characteristics. the steel protection from corrosion using different painting systems and different ways of preparation the surface of steel was analysed. in the research it was seeking to reveal the main advantages and disadvantages comparing different technologies and how the steel surface prepared in different ways can affect the anticorrosive coat characteristics. methods in the research, the chosen rusted steel samples were cut into nine samples with dimensions 150×150 mm and brought into three groups with three samples in each group. according to standard iso 85011, the primary condition of steel was determined as rust grade b (see figure 1). figure 1. according to iso 8501-1 the primary condition of steel was determined as rust grade b in each group the surfaces of specimen were prepared in different ways for the applying the anticorrosive protection. three different preparation methods were selected:  the surface of corroded steel specimen was processed by sand blasting according to the standard iso 8501-1. quartz sand with fraction 0-0.8 mm. was used in the process. the level of surface sa 3 according to standard 8503-1 was achieved and presented in figure 2. according to authors studies the conclusion was made that appropriately unprotected steel structures and mechanisms are affected by corrosion, steel structures lose their strength and the time of exploitation is significantly reduced. one of the most dangerous zones for corrosion is welding seams. in these science publications origin of corrosion grounds, determination of corrosion failures, innovative technologies of smart coating systems and the effect of different environment were analysed. the aim of this work – to analyse the steel constructions’ protection from corrosion installation technologies and to investigate how the level of surface preparation influence the anticorrosive coat characteristics. the steel protection from corrosion using different painting systems and different ways of preparation the surface of steel was analysed. in the research it was seeking to reveal the main advantages and disadvantages comparing different technologies and how the steel surface prepared in different ways can affect the anticorrosive coat characteristics. methods in the research, the chosen rusted steel samples were cut into nine samples with dimensions 150×150 mm and brought into three groups with three samples in each group. according to standard iso 85011, the primary condition of steel was determined as rust grade b (see figure 1). figure 1. according to iso 8501-1 the primary condition of steel was determined as rust grade b in each group the surfaces of specimen were prepared in different ways for the applying the anticorrosive protection. three different preparation methods were selected:  the surface of corroded steel specimen was processed by sand blasting according to the standard iso 8501-1. quartz sand with fraction 0-0.8 mm. was used in the process. the level of surface sa 3 according to standard 8503-1 was achieved and presented in figure 2. in each group the surfaces of specimen were prepared in different ways for the applying the anticorrosive protection. three different preparation methods were selected: _ the surface of corroded steel specimen was processed by sand blasting according to the standard iso 8501-1. quartz sand with fraction 0-0.8 mm. was used in the process. the level of surface sa 3 according to standard 8503-1 was achieved and presented in fig. 2. _ the surface of corroded steel specimen was tooled using wiry brush. according to the standard iso 8501 the level of preparation st 2 was achieved (fig. 3). _ the surface of corroded steel specimen was not prepared in any way. 67 journal of sustainable architecture and civil engineering 2018/1/22 three different paint systems were selected according to standard iso 129445:2007. the paint systems were selected according to the similar categories of environment corrosivity c3 and c4. the extract from the iso 12944-5:2007 standard is presented in fig. 4. in the research chosen paint systems technical characteristics are presented in table 1. investigating how the preparation of steel surface can affect the anticorrosive coating characteristics, the selected three different paint systems were applied on three specimen which were prepared in three different methods. the research scheme is presented in fig. 5. fig. 2 the level of surface preparation sa 3 was achieved by processing the steel using sand blasting method fig. 3 the level of surface preparation st 2 was achieved by tooling the steel using the wiry brush fig. 4 paint systems were selected according to iso 12944-5:2007 standard figure 2. the level of surface preparation sa 3 was achieved by processing the steel using sand blasting method  the surface of corroded steel specimen was tooled using wiry brush. according to the standard iso 8501 the level of preparation st 2 was achieved (figure 3). figure 3. the level of surface preparation st 2 was achieved by tooling the steel using the wiry brush  the surface of corroded steel specimen was not prepared in any way. three different paint systems were selected according to standard iso 12944-5:2007. the paint systems were selected according to the similar categories of environment corrosivity c3 and c4. the extract from the iso 12944-5:2007 standard is presented in figure 4. figure 4. paint systems were selected according to iso 12944-5:2007 standard in the research chosen paint systems technical characteristics are presented in table 1. figure 2. the level of surface preparation sa 3 was achieved by processing the steel using sand blasting method  the surface of corroded steel specimen was tooled using wiry brush. according to the standard iso 8501 the level of preparation st 2 was achieved (figure 3). figure 3. the level of surface preparation st 2 was achieved by tooling the steel using the wiry brush  the surface of corroded steel specimen was not prepared in any way. three different paint systems were selected according to standard iso 12944-5:2007. the paint systems were selected according to the similar categories of environment corrosivity c3 and c4. the extract from the iso 12944-5:2007 standard is presented in figure 4. figure 4. paint systems were selected according to iso 12944-5:2007 standard in the research chosen paint systems technical characteristics are presented in table 1. figure 2. the level of surface preparation sa 3 was achieved by processing the steel using sand blasting method  the surface of corroded steel specimen was tooled using wiry brush. according to the standard iso 8501 the level of preparation st 2 was achieved (figure 3). figure 3. the level of surface preparation st 2 was achieved by tooling the steel using the wiry brush  the surface of corroded steel specimen was not prepared in any way. three different paint systems were selected according to standard iso 12944-5:2007. the paint systems were selected according to the similar categories of environment corrosivity c3 and c4. the extract from the iso 12944-5:2007 standard is presented in figure 4. figure 4. paint systems were selected according to iso 12944-5:2007 standard in the research chosen paint systems technical characteristics are presented in table 1. figure 2. the level of surface preparation sa 3 was achieved by processing the steel using sand blasting method  the surface of corroded steel specimen was tooled using wiry brush. according to the standard iso 8501 the level of preparation st 2 was achieved (figure 3). figure 3. the level of surface preparation st 2 was achieved by tooling the steel using the wiry brush  the surface of corroded steel specimen was not prepared in any way. three different paint systems were selected according to standard iso 12944-5:2007. the paint systems were selected according to the similar categories of environment corrosivity c3 and c4. the extract from the iso 12944-5:2007 standard is presented in figure 4. figure 4. paint systems were selected according to iso 12944-5:2007 standard in the research chosen paint systems technical characteristics are presented in table 1. figure 2. the level of surface preparation sa 3 was achieved by processing the steel using sand blasting method  the surface of corroded steel specimen was tooled using wiry brush. according to the standard iso 8501 the level of preparation st 2 was achieved (figure 3). figure 3. the level of surface preparation st 2 was achieved by tooling the steel using the wiry brush  the surface of corroded steel specimen was not prepared in any way. three different paint systems were selected according to standard iso 12944-5:2007. the paint systems were selected according to the similar categories of environment corrosivity c3 and c4. the extract from the iso 12944-5:2007 standard is presented in figure 4. figure 4. paint systems were selected according to iso 12944-5:2007 standard in the research chosen paint systems technical characteristics are presented in table 1. figure 2. the level of surface preparation sa 3 was achieved by processing the steel using sand blasting method  the surface of corroded steel specimen was tooled using wiry brush. according to the standard iso 8501 the level of preparation st 2 was achieved (figure 3). figure 3. the level of surface preparation st 2 was achieved by tooling the steel using the wiry brush  the surface of corroded steel specimen was not prepared in any way. three different paint systems were selected according to standard iso 12944-5:2007. the paint systems were selected according to the similar categories of environment corrosivity c3 and c4. the extract from the iso 12944-5:2007 standard is presented in figure 4. figure 4. paint systems were selected according to iso 12944-5:2007 standard in the research chosen paint systems technical characteristics are presented in table 1. figure 2. the level of surface preparation sa 3 was achieved by processing the steel using sand blasting method  the surface of corroded steel specimen was tooled using wiry brush. according to the standard iso 8501 the level of preparation st 2 was achieved (figure 3). figure 3. the level of surface preparation st 2 was achieved by tooling the steel using the wiry brush  the surface of corroded steel specimen was not prepared in any way. three different paint systems were selected according to standard iso 12944-5:2007. the paint systems were selected according to the similar categories of environment corrosivity c3 and c4. the extract from the iso 12944-5:2007 standard is presented in figure 4. figure 4. paint systems were selected according to iso 12944-5:2007 standard in the research chosen paint systems technical characteristics are presented in table 1. journal of sustainable architecture and civil engineering 2018/1/22 68 table 1 technical characteristics of paint systems paint system: ak priming coat subsequent coat subsequent coat paint type alkyd alkyd ––––– corrosivity category cm3 cm3 ––––– wft, µm 130 115 ––––– ndft, µm 80 80 ––––– volume solids, % 65 ± 2 52 ± 2 ––––– curing agent mixing ratio ––––– ––––– ––––– paint system: ep, pur priming coat subsequent coat subsequent coat paint type epoxy polyurethane ––––– corrosivity category c4 c4 ––––– wft, µm 260 160 ––––– ndft, µm 160 80 ––––– volume solids, % 80 ± 1 51 ± 1 ––––– curing agent mixing ratio 3:1 7:1 ––––– paint system: zn (r), ep, pur priming coat subsequent coat subsequent coat paint type zinc epoxy polyurethane corrosivity category c4 c4 c4 wft, µm 81 120 120 ndft, µm 60 100 80 volume solids, % 65 ± 1 80 ± 1 51 ± 1 curing agent mixing ratio 4:1 3:1 7:1 fig. 5 the research scheme notes: ak – alkyd paint system; ep, pur – epoxy polyurethane paint system; zn (r), ep, pur – zinc, epoxy, polyurethane paint system. surface preparation rust grade b paint system: ep, pur paint system: ep, pur paint system: ep, pur paint system: ep, pur. zn(r) paint system: ep, pur. zn(r) paint system: ep, pur, zn(r) paint system: alkyd paint system: alkyd paint system: alkyd st 2 sa 3 69 journal of sustainable architecture and civil engineering 2018/1/22 painting conditions: the specimen were painted outside, the air and surface temperature was +7°c, the dew point temperature 4.1°c. the airless painting equipment was used for coating the specimen. the paint systems consist of 2-3 coats. during the painting process in each coating the wft was controlled by special tool. the steel specimen painting process is shown in fig. 6. fig. 6 the steel specimen painting process table 2 dft measurements of specimen level of surface preparation paint system ak ep, pur zn (r), ep, pur priming coat, µm subsequent coat, µm priming coat, µm subsequent coat, µm priming coat, µm subsequent coat, µm subsequent coat, µm b 58 494 110 168 48 148 262 86 242 178 200 42 170 280 59 154 120 158 38 142 240 61 402 136 238 64 151 268 64 154 112 246 60 156 268 st 2 52 248 112 126 49 232 260 76 326 136 230 68 272 320 58 354 110 192 75 220 260 60 304 106 114 51 262 278 52 276 126 164 82 250 280 sa 3 45 170 212 258 58 190 218 70 126 215 350 68 160 198 50 116 204 224 80 198 234 52 306 180 200 72 212 260 48 162 108 148 62 204 260 figure 6. the steel specimen painting process after each coat of paint was completely dry (drying time according to weather conditions given in technical data sheet), the dry film thickness was measured using dft coating thickness gauge. for each specimen five measurements were taken after each coat. dft measurements presented in table 2. table 2. dft measurements of specimen level of surface preparation paint system ak ep, pur zn (r), ep, pur priming coat, µm subsequent coat, µm priming coat, µm subsequent coat, µm priming coat, µm subsequent coat, µm subsequent coat, µm b 58 494 110 168 48 148 262 86 242 178 200 42 170 280 59 154 120 158 38 142 240 61 402 136 238 64 151 268 64 154 112 246 60 156 268 st 2 52 248 112 126 49 232 260 76 326 136 230 68 272 320 58 354 110 192 75 220 260 60 304 106 114 51 262 278 52 276 126 164 82 250 280 sa 3 45 170 212 258 58 190 218 70 126 215 350 68 160 198 50 116 204 224 80 198 234 52 306 180 200 72 212 260 48 162 108 148 62 204 260 rarely exists direct connection between metal spray with salt and corrosion resistance. in the industry the conditions of aggressive atmosphere, which affect the structures significantly differ from artificial atmospheres and is not recommended to assess the long-term effect for anticorrosive coating systems. to accelerate the process of corrosion, the aggressive artificial atmosphere was created according to the standard iso 9227:2017 corrosion tests in artificial atmospheres – salt spray tests (see figure 7). neutral salt spray test is the method in which 5 % neutral sodium chloride dissolving is automated in controlled environment. the sufficient amount of sodium chloride is dissolved in distilled water with specific conduction not exceeding the 20 µs/cm at 25 ± 2°c to get the concentration of 50 ± 5 g/l. the steel samples were kept in artificial atmosphere for 500 hours. figure 6. the steel specimen painting process after each coat of paint was completely dry (drying time according to weather conditions given in technical data sheet), the dry film thickness was measured using dft coating thickness gauge. for each specimen five measurements were taken after each coat. dft measurements presented in table 2. table 2. dft measurements of specimen level of surface preparation paint system ak ep, pur zn (r), ep, pur priming coat, µm subsequent coat, µm priming coat, µm subsequent coat, µm priming coat, µm subsequent coat, µm subsequent coat, µm b 58 494 110 168 48 148 262 86 242 178 200 42 170 280 59 154 120 158 38 142 240 61 402 136 238 64 151 268 64 154 112 246 60 156 268 st 2 52 248 112 126 49 232 260 76 326 136 230 68 272 320 58 354 110 192 75 220 260 60 304 106 114 51 262 278 52 276 126 164 82 250 280 sa 3 45 170 212 258 58 190 218 70 126 215 350 68 160 198 50 116 204 224 80 198 234 52 306 180 200 72 212 260 48 162 108 148 62 204 260 rarely exists direct connection between metal spray with salt and corrosion resistance. in the industry the conditions of aggressive atmosphere, which affect the structures significantly differ from artificial atmospheres and is not recommended to assess the long-term effect for anticorrosive coating systems. to accelerate the process of corrosion, the aggressive artificial atmosphere was created according to the standard iso 9227:2017 corrosion tests in artificial atmospheres – salt spray tests (see figure 7). neutral salt spray test is the method in which 5 % neutral sodium chloride dissolving is automated in controlled environment. the sufficient amount of sodium chloride is dissolved in distilled water with specific conduction not exceeding the 20 µs/cm at 25 ± 2°c to get the concentration of 50 ± 5 g/l. the steel samples were kept in artificial atmosphere for 500 hours. figure 6. the steel specimen painting process after each coat of paint was completely dry (drying time according to weather conditions given in technical data sheet), the dry film thickness was measured using dft coating thickness gauge. for each specimen five measurements were taken after each coat. dft measurements presented in table 2. table 2. dft measurements of specimen level of surface preparation paint system ak ep, pur zn (r), ep, pur priming coat, µm subsequent coat, µm priming coat, µm subsequent coat, µm priming coat, µm subsequent coat, µm subsequent coat, µm b 58 494 110 168 48 148 262 86 242 178 200 42 170 280 59 154 120 158 38 142 240 61 402 136 238 64 151 268 64 154 112 246 60 156 268 st 2 52 248 112 126 49 232 260 76 326 136 230 68 272 320 58 354 110 192 75 220 260 60 304 106 114 51 262 278 52 276 126 164 82 250 280 sa 3 45 170 212 258 58 190 218 70 126 215 350 68 160 198 50 116 204 224 80 198 234 52 306 180 200 72 212 260 48 162 108 148 62 204 260 rarely exists direct connection between metal spray with salt and corrosion resistance. in the industry the conditions of aggressive atmosphere, which affect the structures significantly differ from artificial atmospheres and is not recommended to assess the long-term effect for anticorrosive coating systems. to accelerate the process of corrosion, the aggressive artificial atmosphere was created according to the standard iso 9227:2017 corrosion tests in artificial atmospheres – salt spray tests (see figure 7). neutral salt spray test is the method in which 5 % neutral sodium chloride dissolving is automated in controlled environment. the sufficient amount of sodium chloride is dissolved in distilled water with specific conduction not exceeding the 20 µs/cm at 25 ± 2°c to get the concentration of 50 ± 5 g/l. the steel samples were kept in artificial atmosphere for 500 hours. after each coat of paint was completely dry (drying time according to weather conditions given in technical data sheet), the dry film thickness was measured using dft coating thickness gauge. for each specimen five measurements were taken after each coat. dft measurements presented in table 2. journal of sustainable architecture and civil engineering 2018/1/22 70 rarely exists direct connection between metal spray with salt and corrosion resistance. in the industry the conditions of aggressive atmosphere, which affect the structures significantly differ from artificial atmospheres and is not recommended to assess the long-term effect for anticorrosive coating systems. to accelerate the process of corrosion, the aggressive artificial atmosphere was created according to the standard iso 9227:2017 corrosion tests in artificial atmospheres – salt spray tests (see fig. 7). neutral salt spray test is the method in which 5 % neutral sodium chloride fig. 7 equipment for salt spray test in artificial atmosphere fig. 8 photo fixation and description of specimen in salt spray artificial atmosphere duration, hours specimen photo fixation in salt spray artificial atmosphere specimen characterisation 120 figure 7. equipment for salt spray test in artificial atmosphere the specimen in salt spray artificial atmosphere were photo fixated and visually analysed every 120 hours. photo fixation and description is presented in figure 8. duration, hours specimen photo fixation in salt spray artificial atmosphere specimen characterisation 120 the steel specimen visually examined in 120 hours in salt spray artificial environment. no obvious changes were noticed in research zones of specimen. corrosion marks noticed on the edges of specimen and welding spatters. 240 the steel specimen visually examined in 240 hours in salt spray artificial environment. no visible changes were noticed in specimen research zones. more corrosion marks appeared on the edges and spatters of the specimen. 360 the steel specimen visually examined in 360 hours in salt spray artificial environment. research zones of specimen were not affected by corrosion. more corrosion marks continued to appear on the edges and spatters of the specimen. the steel specimen visually examined in 120 hours in salt spray artificial environment. no obvious changes were noticed in research zones of specimen. corrosion marks noticed on the edges of specimen and welding spatters. 240 figure 7. equipment for salt spray test in artificial atmosphere the specimen in salt spray artificial atmosphere were photo fixated and visually analysed every 120 hours. photo fixation and description is presented in figure 8. duration, hours specimen photo fixation in salt spray artificial atmosphere specimen characterisation 120 the steel specimen visually examined in 120 hours in salt spray artificial environment. no obvious changes were noticed in research zones of specimen. corrosion marks noticed on the edges of specimen and welding spatters. 240 the steel specimen visually examined in 240 hours in salt spray artificial environment. no visible changes were noticed in specimen research zones. more corrosion marks appeared on the edges and spatters of the specimen. 360 the steel specimen visually examined in 360 hours in salt spray artificial environment. research zones of specimen were not affected by corrosion. more corrosion marks continued to appear on the edges and spatters of the specimen. the steel specimen visually examined in 240 hours in salt spray artificial environment. no visible changes were noticed in specimen research zones. more corrosion marks appeared on the edges and spatters of the specimen. 360 figure 7. equipment for salt spray test in artificial atmosphere the specimen in salt spray artificial atmosphere were photo fixated and visually analysed every 120 hours. photo fixation and description is presented in figure 8. duration, hours specimen photo fixation in salt spray artificial atmosphere specimen characterisation 120 the steel specimen visually examined in 120 hours in salt spray artificial environment. no obvious changes were noticed in research zones of specimen. corrosion marks noticed on the edges of specimen and welding spatters. 240 the steel specimen visually examined in 240 hours in salt spray artificial environment. no visible changes were noticed in specimen research zones. more corrosion marks appeared on the edges and spatters of the specimen. 360 the steel specimen visually examined in 360 hours in salt spray artificial environment. research zones of specimen were not affected by corrosion. more corrosion marks continued to appear on the edges and spatters of the specimen. the steel specimen visually examined in 360 hours in salt spray artificial environment. research zones of specimen were not affected by corrosion. more corrosion marks continued to appear on the edges and spatters of the specimen. 500 500 the steel specimen visually examined in 500 hours in salt spray artificial environment. the specimen research zones were not affected by corrosion. the corrosion marks were found on the edges and welding spatters. the specimen with alkyd paint system had outspread corrosion around the spatters. the ep, pur and zn (r), ep, pur paint systems had no impact of corrosion outspread around the spatters. figure 8. photo fixation and description of specimen in salt spray artificial atmosphere the influence of surface preparation the anticorrosive coating characteristics was investigated and the results were assessed referencing the methodology for frosio inspectors “inspection of corrosion protective coating” of norway institute “teknologisk institut”. results in the research the specimen were prepared by sand blasting using quartz sand (fraction 0-0.8 mm.) and tooling using the wiry brush. the surface preparation levels sa 3 and st 2 were achieved. the tests were also performed with specimen which were not prepared in any way with rust grade b. correct steel surface preparation and paint system application is complex and precision requiring process. usually industrial paint systems have two components paint systems with two or three coats and each paint system requires different steel surfaces preparation level and method, needs control of thickness in every coat. by applying the paint on the specimen using the airless paint equipment it was difficult to achieve the equal thickness of coating. dry film thicknesses were achieved in 20% error. after the salt spray test the specimen were properly cleaned. anticorrosive coating characteristics for differently prepared surfaces were analysed by testing the adhesion (pull-off test) according to the standard iso 4624:2016 using digital adhesion gauge “elcometer 506”. to bond the gauge cylinder to the top coat of specimen the glue “locitite 435” was used. investigating how the preparation of surface influences the anticorrosive coating characteristics, the results were assessed referencing the methodology for frosio inspectors “inspection of corrosion protective coating” of norway institute “teknologisk institutt” (the example is given in figure 9). three adhesion tests were carried on each steel specimen. the tests result presented in table 3. figure 9. adhesion tests results assessing the reference of methodology for frosio inspectors “inspection of corrosion protective coating” the steel specimen visually examined in 500 hours in salt spray artificial environment. the specimen research zones were not affected by corrosion. the corrosion marks were found on the edges and welding spatters. the specimen with alkyd paint system had outspread corrosion around the spatters. the ep, pur and zn (r), ep, pur paint systems had no impact of corrosion outspread around the spatters. figure 7. equipment for salt spray test in artificial atmosphere the specimen in salt spray artificial atmosphere were photo fixated and visually analysed every 120 hours. photo fixation and description is presented in figure 8. duration, hours specimen photo fixation in salt spray artificial atmosphere specimen characterisation 120 the steel specimen visually examined in 120 hours in salt spray artificial environment. no obvious changes were noticed in research zones of specimen. corrosion marks noticed on the edges of specimen and welding spatters. 240 the steel specimen visually examined in 240 hours in salt spray artificial environment. no visible changes were noticed in specimen research zones. more corrosion marks appeared on the edges and spatters of the specimen. 360 the steel specimen visually examined in 360 hours in salt spray artificial environment. research zones of specimen were not affected by corrosion. more corrosion marks continued to appear on the edges and spatters of the specimen. dissolving is automated in controlled environment. the sufficient amount of sodium chloride is dissolved in distilled water with specific conduction not exceeding the 20 µs/cm at 25 ± 2°c to get the concentration of 50 ± 5 g/l. the steel samples were kept in artificial atmosphere for 500 hours. the specimen in salt spray artificial atmosphere were photo fixated and visually analysed every 120 hours. photo fixation and description is presented in fig. 8. 71 journal of sustainable architecture and civil engineering 2018/1/22 the influence of surface preparation the anticorrosive coating characteristics was investigated and the results were assessed referencing the methodology for frosio inspectors “inspection of corrosion protective coating” of norway institute “teknologisk institut”. in the research the specimen were prepared by sand blasting using quartz sand (fraction 0-0.8 mm.) and tooling using the wiry brush. the surface preparation levels sa 3 and st 2 were achieved. the tests were also performed with specimen which were not prepared in any way with rust grade b. correct steel surface preparation and paint system application is complex and precision requiring process. usually industrial paint systems have two components paint systems with two or three coats and each paint system requires different steel surfaces preparation level and method, needs control of thickness in every coat. by applying the paint on the specimen using the airless paint equipment it was difficult to achieve the equal thickness of coating. dry film thicknesses were achieved in 20% error. after the salt spray test the specimen were properly cleaned. anticorrosive coating characteristics for differently prepared surfaces were analysed by testing the adhesion (pull-off test) according to the standard iso 4624:2016 using digital adhesion gauge “elcometer 506”. to bond the gauge cylinder to the top coat of specimen the glue “locitite 435” was used. investigating how the preparation of surface influences the anticorrosive coating characteristics, the results were assessed referencing the methodology for frosio inspectors “inspection of corrosion protective coating” of norway institute “teknologisk institutt” (the example is given in fig. 9). three adhesion tests were results fig. 9 adhesion tests results assessing the reference of methodology for frosio inspectors “inspection of corrosion protective coating” 500 the steel specimen visually examined in 500 hours in salt spray artificial environment. the specimen research zones were not affected by corrosion. the corrosion marks were found on the edges and welding spatters. the specimen with alkyd paint system had outspread corrosion around the spatters. the ep, pur and zn (r), ep, pur paint systems had no impact of corrosion outspread around the spatters. figure 8. photo fixation and description of specimen in salt spray artificial atmosphere the influence of surface preparation the anticorrosive coating characteristics was investigated and the results were assessed referencing the methodology for frosio inspectors “inspection of corrosion protective coating” of norway institute “teknologisk institut”. results in the research the specimen were prepared by sand blasting using quartz sand (fraction 0-0.8 mm.) and tooling using the wiry brush. the surface preparation levels sa 3 and st 2 were achieved. the tests were also performed with specimen which were not prepared in any way with rust grade b. correct steel surface preparation and paint system application is complex and precision requiring process. usually industrial paint systems have two components paint systems with two or three coats and each paint system requires different steel surfaces preparation level and method, needs control of thickness in every coat. by applying the paint on the specimen using the airless paint equipment it was difficult to achieve the equal thickness of coating. dry film thicknesses were achieved in 20% error. after the salt spray test the specimen were properly cleaned. anticorrosive coating characteristics for differently prepared surfaces were analysed by testing the adhesion (pull-off test) according to the standard iso 4624:2016 using digital adhesion gauge “elcometer 506”. to bond the gauge cylinder to the top coat of specimen the glue “locitite 435” was used. investigating how the preparation of surface influences the anticorrosive coating characteristics, the results were assessed referencing the methodology for frosio inspectors “inspection of corrosion protective coating” of norway institute “teknologisk institutt” (the example is given in figure 9). three adhesion tests were carried on each steel specimen. the tests result presented in table 3. figure 9. adhesion tests results assessing the reference of methodology for frosio inspectors “inspection of corrosion protective coating” 500 the steel specimen visually examined in 500 hours in salt spray artificial environment. the specimen research zones were not affected by corrosion. the corrosion marks were found on the edges and welding spatters. the specimen with alkyd paint system had outspread corrosion around the spatters. the ep, pur and zn (r), ep, pur paint systems had no impact of corrosion outspread around the spatters. figure 8. photo fixation and description of specimen in salt spray artificial atmosphere the influence of surface preparation the anticorrosive coating characteristics was investigated and the results were assessed referencing the methodology for frosio inspectors “inspection of corrosion protective coating” of norway institute “teknologisk institut”. results in the research the specimen were prepared by sand blasting using quartz sand (fraction 0-0.8 mm.) and tooling using the wiry brush. the surface preparation levels sa 3 and st 2 were achieved. the tests were also performed with specimen which were not prepared in any way with rust grade b. correct steel surface preparation and paint system application is complex and precision requiring process. usually industrial paint systems have two components paint systems with two or three coats and each paint system requires different steel surfaces preparation level and method, needs control of thickness in every coat. by applying the paint on the specimen using the airless paint equipment it was difficult to achieve the equal thickness of coating. dry film thicknesses were achieved in 20% error. after the salt spray test the specimen were properly cleaned. anticorrosive coating characteristics for differently prepared surfaces were analysed by testing the adhesion (pull-off test) according to the standard iso 4624:2016 using digital adhesion gauge “elcometer 506”. to bond the gauge cylinder to the top coat of specimen the glue “locitite 435” was used. investigating how the preparation of surface influences the anticorrosive coating characteristics, the results were assessed referencing the methodology for frosio inspectors “inspection of corrosion protective coating” of norway institute “teknologisk institutt” (the example is given in figure 9). three adhesion tests were carried on each steel specimen. the tests result presented in table 3. figure 9. adhesion tests results assessing the reference of methodology for frosio inspectors “inspection of corrosion protective coating” carried on each steel specimen. the tests result presented in table 3. in table 3 the pull-off tests were analysed in detail referencing the methodology of “inspection of corrosion protective coating” and the effect of steel surface preparation depending on paint system was noticed. in surface preparation sa 3 and st 2 every paint system performed slightly different but positive result. the tests with specimen, which were not prepared in any way, the results were significantly worse with one component alkyd paint system and cohesion results were obtained. pull-off strength results presented in fig. 10, 11 and 12. adhesion tests comparison results shown in fig. 13. comparing the pull-off tests results the average values of three tests for each specimen were assessed. the adhesion tests’ results of each specimen with every paint system and surface preparation were <5 mpa. considering ep, pur and zn (r), ep, pur coating systems the pull-off strength results were very similar with variations of 1.8 – 4.03 % between the systems considering the preparation method. alkyd paint system tests results significantly differentiated and the pull-off journal of sustainable architecture and civil engineering 2018/1/22 72 paint system ak (c3m) ak (c3m) ak (c3m) ep, pur (c4) ep, pur (c4) ep, pur (c4) zn (r), ep, pur (c4) zn (r), ep, pur (c4) zn (r), ep, pur (c4) steel substrate preparation b st 2 sa 3 b st 2 sa 3 b st 2 sa 3 no. of coats 2 2 2 2 2 2 3 3 3 first coat thickness 80 80 80 160 160 160 60 60 60 second coat thickness 80 80 80 80 80 80 100 100 100 third coat thickness ------------80 80 80 equipment used elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 on which layer test performed temalac ab 70 temalac ab 70 temalac ab 70 hemathene topcoat 55210 hemathene topcoat 55210 hemathene topcoat 55210 hemathene topcoat 55210 hemathene topcoat 55210 hemathene topcoat 55210 type of break. test no. 1 90% a 10% b 50% a 50% b 100% b/c 5% c 95% y/z 10% c 90% y/z 10% c 90% y/z 15% c 85% y/z 100% c 100% y/z type of break. test no. 2 85% a 15% b 45% a 55% b 100% b/c 5% c 95% y/z 100% y/z 5% c 95% y/z 10% c 90% y/z 100% y/z 100% y/z type of break. test no. 3 40% a 60% b 20% a 80% b 100% b/c 5% c 95% y/z 30% c 70% y/z 15% c 85% y/z 10% c 90% y/z 5% c 95% y/z 5% c 95% y/z table 3 adhesion tests results fig. 10 alkyd paint system pull-off tests results 73 journal of sustainable architecture and civil engineering 2018/1/22 fig. 11 epoxy and polyurethane paint system pull-off tests results fig. 12 zinc, epoxy and polyurethane paint system pull-off tests results fig. 13 comparison of adhesion tests results (average values considered) table 3. adhesion tests results paint system ak (c3m) ak (c3m) ak (c3m) ep, pur (c4) ep, pur (c4) ep, pur (c4) zn (r), ep, pur (c4) zn (r), ep, pur (c4) zn (r), ep, pur (c4) steel substrate preparation b st 2 sa 3 b st 2 sa 3 b st 2 sa 3 no. of coats 2 2 2 2 2 2 3 3 3 first coat thickness 80 80 80 160 160 160 60 60 60 second coat thickness 80 80 80 80 80 80 100 100 100 third coat thickness ------------80 80 80 equipment used elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 elcometer 506 on which layer test performed temalac ab 70 temalac ab 70 temalac ab 70 hemathene topcoat 55210 hemathene topcoat 55210 hemathene topcoat 55210 hemathene topcoat 55210 hemathene topcoat 55210 hemathene topcoat 55210 type of break. test no. 1 90% a 10% b 50% a 50% b 100% b/c 5% c 95% y/z 10% c 90% y/z 10% c 90% y/z 15% c 85% y/z 100% c 100% y/z type of break. test no. 2 85% a 15% b 45% a 55% b 100% b/c 5% c 95% y/z 100% y/z 5% c 95% y/z 10% c 90% y/z 100% y/z 100% y/z type of break. test no. 3 40% a 60% b 20% a 80% b 100% b/c 5% c 95% y/z 30% c 70% y/z 15% c 85% y/z 10% c 90% y/z 5% c 95% y/z 5% c 95% y/z in table 3 the pull-off tests were analysed in detail referencing the methodology of “inspection of corrosion protective coating” and the effect of steel surface preparation depending on paint system was noticed. in surface preparation sa 3 and st 2 every paint system performed slightly different but positive result. the tests with specimen, which were not prepared in any way, the results were significantly worse with one component alkyd paint system and cohesion results were obtained. pulloff strength results presented in figure 10, 11 and 12. adhesion tests comparison results shown in figure 13. figure 10. alkyd paint system pull-off tests results figure 11. epoxy and polyurethane paint system pulloff tests results figure 12. zinc, epoxy and polyurethane paint system pull-off tests results figure 13. comparison of adhesion tests results (average values considered) comparing the pull-off tests results the average values of three tests for each specimen were assessed. the adhesion tests’ results of each specimen with every paint system and surface preparation were <5 mpa. considering ep, pur and zn (r), ep, pur coating systems the pull-off strength results were very similar with variations of 1.8 – 4.03 % between the systems considering the preparation method. alkyd paint system tests results significantly differentiated and the pull-off strength values were 14 – 16 % lower comparing to the average results of ep, pur and zn (r), ep, pur coating systems. assessing the substratum preparation method effect for coating strength characteristic the results were higher and directly related to the preparation method. jamali and mills, 2014 investigated the influence of surface preparation on performance of alkyd coatings on steel. degreasing, abrasion with emery, acid pickling, hydroblasting and wet abrasive blasting methods were used to modify the surface of steel before painting. in their study it was shown that the level of recovery adhesion may not be a reliable criterion for the corrosion protection in some cases. it was demonstrated that increasing surface roughness together with a stable surface oxide effectively increases on the interfacial bonding. comparing the researches with different ways of steel surface preparation and different methods of analysis, the results achieved were very similar and revealed that the value of adhesion was subordinate in determining the anticorrosion performance of an organic coating. conclusions 1. steel specimen coated in different painting systems were kept in salt spray artificial atmosphere for 500 hours delivered the conclusion that properly prepared surface in the research zones of specimen had no impact of corrosion uprising. corrosion marks developed on the edges and around the spatters of the specimen, where inappropriate surface preparation was performed. 2. although the experimentation was short-term and adhesion tests results independently from the surface preparation method were positive <5 mpa but when pull-off tests were examined visually between the anticorrosive coats and the cylinder revealed more definite conclusions that in some cases surface preparation affected the anticorrosive coating characteristics. referencing the results using this method the worst characteristics were recorded in specimen with surface preparation of st 2 or rust grade b coated in one component alkyd paint system. determined that the film in these specimens were detached from the substratum of steel. the figure 12. zinc, epoxy and polyurethane paint system pull-off tests results figure 13. comparison of adhesion tests results (average values considered) comparing the pull-off tests results the average values of three tests for each specimen were assessed. the adhesion tests’ results of each specimen with every paint system and surface preparation were <5 mpa. considering ep, pur and zn (r), ep, pur coating systems the pull-off strength results were very similar with variations of 1.8 – 4.03 % between the systems considering the preparation method. alkyd paint system tests results significantly differentiated and the pull-off strength values were 14 – 16 % lower comparing to the average results of ep, pur and zn (r), ep, pur coating systems. assessing the substratum preparation method effect for coating strength characteristic the results were higher and directly related to the preparation method. jamali and mills, 2014 investigated the influence of surface preparation on performance of alkyd coatings on steel. degreasing, abrasion with emery, acid pickling, hydroblasting and wet abrasive blasting methods were used to modify the surface of steel before painting. in their study it was shown that the level of recovery adhesion may not be a reliable criterion for the corrosion protection in some cases. it was demonstrated that increasing surface roughness together with a stable surface oxide effectively increases on the interfacial bonding. comparing the researches with different ways of steel surface preparation and different methods of analysis, the results achieved were very similar and revealed that the value of adhesion was subordinate in determining the anticorrosion performance of an organic coating. conclusions 1. steel specimen coated in different painting systems were kept in salt spray artificial atmosphere for 500 hours delivered the conclusion that properly prepared surface in the research zones of specimen had no impact of corrosion uprising. corrosion marks developed on the edges and around the spatters of the specimen, where inappropriate surface preparation was performed. 2. although the experimentation was short-term and adhesion tests results independently from the surface preparation method were positive <5 mpa but when pull-off tests were examined visually between the anticorrosive coats and the cylinder revealed more definite conclusions that in some cases surface preparation affected the anticorrosive coating characteristics. referencing the results using this method the worst characteristics were recorded in specimen with surface preparation of st 2 or rust grade b coated in one component alkyd paint system. determined that the film in these specimens were detached from the substratum of steel. the figure 12. zinc, epoxy and polyurethane paint system pull-off tests results figure 13. comparison of adhesion tests results (average values considered) comparing the pull-off tests results the average values of three tests for each specimen were assessed. the adhesion tests’ results of each specimen with every paint system and surface preparation were <5 mpa. considering ep, pur and zn (r), ep, pur coating systems the pull-off strength results were very similar with variations of 1.8 – 4.03 % between the systems considering the preparation method. alkyd paint system tests results significantly differentiated and the pull-off strength values were 14 – 16 % lower comparing to the average results of ep, pur and zn (r), ep, pur coating systems. assessing the substratum preparation method effect for coating strength characteristic the results were higher and directly related to the preparation method. jamali and mills, 2014 investigated the influence of surface preparation on performance of alkyd coatings on steel. degreasing, abrasion with emery, acid pickling, hydroblasting and wet abrasive blasting methods were used to modify the surface of steel before painting. in their study it was shown that the level of recovery adhesion may not be a reliable criterion for the corrosion protection in some cases. it was demonstrated that increasing surface roughness together with a stable surface oxide effectively increases on the interfacial bonding. comparing the researches with different ways of steel surface preparation and different methods of analysis, the results achieved were very similar and revealed that the value of adhesion was subordinate in determining the anticorrosion performance of an organic coating. conclusions 1. steel specimen coated in different painting systems were kept in salt spray artificial atmosphere for 500 hours delivered the conclusion that properly prepared surface in the research zones of specimen had no impact of corrosion uprising. corrosion marks developed on the edges and around the spatters of the specimen, where inappropriate surface preparation was performed. 2. although the experimentation was short-term and adhesion tests results independently from the surface preparation method were positive <5 mpa but when pull-off tests were examined visually between the anticorrosive coats and the cylinder revealed more definite conclusions that in some cases surface preparation affected the anticorrosive coating characteristics. referencing the results using this method the worst characteristics were recorded in specimen with surface preparation of st 2 or rust grade b coated in one component alkyd paint system. determined that the film in these specimens were detached from the substratum of steel. the journal of sustainable architecture and civil engineering 2018/1/22 74 strength values were 14 – 16 % lower comparing to the average results of ep, pur and zn (r), ep, pur coating systems. assessing the substratum preparation method effect for coating strength characteristic the results were higher and directly related to the preparation method. jamali and mills, 2014 investigated the influence of surface preparation on performance of alkyd coatings on steel. degreasing, abrasion with emery, acid pickling, hydroblasting and wet abrasive blasting methods were used to modify the surface of steel before painting. in their study it was shown that the level of recovery adhesion may not be a reliable criterion for the corrosion protection in some cases. it was demonstrated that increasing surface roughness together with a stable surface oxide effectively increases on the interfacial bonding. comparing the researches with different ways of steel surface preparation and different methods of analysis, the results achieved were very similar and revealed that the value of adhesion was subordinate in determining the anticorrosion performance of an organic coating. 1 steel specimen coated in different painting systems were kept in salt spray artificial at-mosphere for 500 hours delivered the conclusion that properly prepared surface in the research zones of specimen had no impact of corrosion uprising. corrosion marks developed on the edges and around the spatters of the specimen, where inappropriate surface preparation was performed. 2 although the experimentation was short-term and adhesion tests results independently from the surface preparation method were positive <5 mpa but when pull-off tests were examined visually between the anticorrosive coats and the cylinder revealed more definite conclusions that in some cases surface preparation affected the anticorrosive coating characteristics. referencing the results using this method the worst characteristics were recorded in specimen with surface preparation of st 2 or rust grade b coated in one component alkyd paint system. determined that the film in these specimens were detached from the substratum of steel. the specimen with zn (r), ep, pur and ep, pur paint systems had insignificant alteration considering the steel surface preparation method. 3 in the research comparing the paint systems used to protect the steel surface from corro-sion the best results were achieved by coating the surface using two component ep, pur and zn(r), ep, pur paint systems. pull-off strength results variations between the systems were marginal and ranged from 1.8 to 4.03 % considering the same preparation methods. comparing ep, pur and zn(r), ep, pur to alkyd paint system the latter pull-off test results were 15.2 % lower considering surface preparation sa 3, 16.0 % lower considering surface preparation st 2 and 14 % lower results when no preparation was performed. the results demonstrate that barrier and cathodic anticorrosive protection have more efficient characteristics to protect the steel from corrosion in average industrial atmosphere comparing to ak coating systems. 4 from pull-off tests reports it was determined that using different paint systems, the level of steel surface preparation directly affects anticorrosive coating characteristics. between the specimen with no preparation with surface rust grade b and with preparation to st 2 the pull-off strength values increased from 8.86 to 14.55 % subject to the paint system. the most increase in values was determined when the surfaces were coated in zn(r), ep, pur and the least when the surfaces were coated in ak paint system. comparing steel surface preparation st 2 and sa 3 the pull-off strength values increased 9.2 – 14.37 %. calculated that zn(r), ep, pur coating characteristics were least affected considering preparation level st 2 and sa 3. ak paint system was affected considerably comparing insignificant values of increase between rust grade b and st 2. from the results it was determined that steel surface preparation level affects the anticorrosive coating characteristics. conclusions 75 journal of sustainable architecture and civil engineering 2018/1/22 bayliss d.a., deacon d.h. steelwork corrosion control, 2002. carpen l. corrosion of stainless steel in fire protection systems, 2008; vtt-r-01556-08. hoeke l. j. l., moser d.r., singh m.p., kahn f.l. kurtis e.k. degradation of steel girder bridge bearing systems by corrosion, 2009. inspection of corrosion protective coatings ns 476-frosio. norway: teknologisk institutt, 2012. jamali s., mills j. steel surface preparation prior to painting and its impact on protective performance of organic coating, 2014; 77: 2091-2099. kjernsmo d., kjell k. frosio inspectors’ handbook: corrosion protection. norway, 2008. lst en iso 11126-1. preparation of steel substrates before application of paints and related products – specifications for non-metallic blast-cleaning abrasives part 1: general introduction and classification (iso 11126-1:1993, including technical corrigenda 1:1997 and 2:1997): lithuanian standard. vilnius: lithuanian standardization department, 2002. lst en iso 12944-5. paints and varnishes – corrosion protection of steel structures by protective paint systems part 7: protective paint systems (iso 12944-5:2007): lithuanian standard. vilnius: lithuanian standardization department, 2007. lst en iso 2808. paints and varnishes – determination of film thickness (iso 2808:2007): lithuanian standard. vilnius: lithuanian standardization department, 2007. lst en iso 4624. paints and varnishes – pull-off test for adhesion (iso 4624:20016): lithuanian standard. vilnius: lithuanian standardization department, 2016. lst en iso 9227. corrosion tests in artificial atmospheres – salt spray tests (iso 9227:2017): lithuanian standard. vilnius: lithuanian standardization department, 2017. melchers r.e. modelling immersion corrosion of structural steels in natural fresh and brackish waters, 2006; 48: 4174-4201. phipip a., schweitzer p.e. corrosion engineering handbook, second edition – 3 volume set, 2006. ramezanzadeh b., niroumandrad s., ahmadi a., mahdavian m., moghadam m. h. m. enhancement of barrier and corrosion protection performance of an epoxy coating through wet transfer of amino functionalized graphene oxide, 2016; 103: 283-304. roberge p. r. handbook of corrosion engineering, 2000. roselli s.n., amo b., carbonari r.o., sarili a.r., romagnoli r. painting rusted steel: the role of aluminium phosphosilicate, 2013; 74: 194-205. ulaeto b.s., rajan r., pancrecious k.j., rajan t. p. d., pai b.c developments in smart anticorrosive coatings with multifunctional characteristics, 2017; 111: 294-314. references paulius kavaliauskas master student kaunas university of technology, faculty of civil engineering and architecture main research area civil engineering, construction technology address studentų str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: k.paulius@yahoo.com mindaugas daukšys professor kaunas university of technology, faculty of civil engineering and architecture. main research area civil engineering, construction technology address studentų str. 48, lt-51367 kaunas, lithuania tel. +370 37 300479 e-mail: mindaugas.dauksys@ktu.lt about the authors 47 journal of sustainable architecture and civil engineering 2016/2/15 *corresponding author: aurelija.levinskyte@ktu.lt the influence of thermal bridges for buildings energy consumption of “a“ energy efficiency class received 2016/06/21 accepted after revision 2016/09/08 journal of sustainable architecture and civil engineering vol. 2 / no. 15 / 2016 pp. 44-58 doi 10.5755/j01.sace.15.2.15351 © kaunas university of technology the influence of thermal bridges for buildings energy consumption of “a“ energy efficiency class jsace 2/15 http://dx.doi.org/10.5755/j01.sace.15.2.15351 aurelija levinskytė* kaunas university of technology, institute of architecture and construction tunelio st. 60, lt-44405 kaunas, lithuania karolis banionis, valdemaras geležiūnas kaunas university of technology, institute of architecture and construction tunelio st. 60, lt-44405 kaunas, lithuania university of technology, faculty of civil engineering and architecture studentų st. 48, lt51367 kaunas, lithuania from 2016 “a” energy efficiency class buildings should be designed and built in lithuania, as their energy consumptions are considerably less comparing with the ones that were built before. in order to meet high requirements of “a” energy efficiency class buildings should be used new energy efficient structural and insulating solutions should be made. in order to evaluate overall heat losses in these joints more exactly it is required to calculate values of heat transmission coefficients of linear thermal bridges in “a” energy class buildings. the project of semi-detached building was chosen in order to analyse influence of linear thermal bridges for building’s energy consumption as there are all kinds of linear thermal bridges which values must be calculated. buildings energy efficiency designing program, which based on en iso 13790, was used to calculate building’s heat losses. heat transmission coefficients of linear thermal bridges were calculated using program therm. two variations were analysed: building’s energy consumptions are close to the lowest point of a class requirements when building’s envelopes and joints of units in joint places are the same as they are in currently built houses; and effective energy solutions of building’s joints. the results of analysis showed that requirements of “a” class can be reached using ordinary solutions for building’s envelopes and joint units but if linear thermal bridges are designed like that, it makes 16 % heat losses through envelopes, and it is similar to heat losses through building’s walls (17 %), furthermore, it is about 1.5 times bigger than heat losses through roof (10 %) or floors (10 %). specific heat losses of thermal bridges make 7.80 kwh/m² per year. the biggest overall heat losses are through walls and windows joint thermal bridges (specific heat losses make 13.55w/k). another significant part of heat losses comes from walls and floor joints (specific heat losses make 11.88w/k). after solutions of buildings with energy effective building’s envelopes and units joints were analysed it can be stated that overall heat losses decreased about 10 kwh/m² per year, it is 20 %. heat losses through journal of sustainable architecture and civil engineering 2016/2/15 48 thermal bridges make only 3 % of overall heat losses through envelopes, it is 122 kwh/m² per year. according to results of the analyse general specifications were made for designing building envelopes of “a” energy efficient class: _ the building of “a” class can be designed using ordinary solutions of linear thermal bridges, bigger heat losses through thermal bridges can be covered by increasing thickness of thermal insulating layers and using windows of better thermal behaviour but as a result the costs of building house increase too. _ when effective solutions of linear thermal bridges are used, the same energy efficiency of the building can be reached using less thermal insulating layers, windows and doors of less thermal behaviour if the building of better energy characteristics is designed. keywords: energy efficiency class, linear thermal bridges, overall heat losses, thermal insulation. introduction a significant part of heat losses in a building can be due to thermal bridges. a thermal bridge is a part of the building envelope where the otherwise uniform thermal resistance is significantly changed by full or partial penetration of the building envelope by materials with a different thermal conductivity and/or a change in thickness of the fabric and/or a difference between internal and external areas (en iso 10211:2008). constructional nodes, in which most cases create linear thermal bridges, are these: _ external and internal wall corners (fig. 1 a, b) _ different thickness of external wall (fig. 1 c); _ the junction of outer wall and floor slab (fig. 2 a); _ the junction of outer wall and window/door (fig. 2 b); _ the junction of outer wall and balcony slab (fig. 2 c) a b z a b z fig. 1 constructional nodes of linear thermal bridges: a) external wall corner; b) internal wall corner; c) different thickness of external wall fig. 2 constructional nodes of linear thermal bridges: a) the junction of outer wall and floor slab; b) the junction of outer wall and window; c) the junction of outer wall and balcony slab 49 journal of sustainable architecture and civil engineering 2016/2/15 _ the junction of outer wall and roof (fig. 3 a); _ the junction of outer wall and floor on the ground (fig. 3 b). according to different sources, the actual weight of thermal bridges in the energy demand of dwellings can vary from 5 to 39% (quinten, feldheim , 2016). therefore, influence of linear thermal bridges for total building heat losses is significant and especially in designing “a“ energy efficiency class buildings. heat losses of building through linear thermal bridges can be significantly reduced if correct decisions in designing junctions of envelopes are chosen. sometimes the right solution of problem nodes can determine energy efficiency class of the building. in order to avoid large heat loss through thermal bridges their structural nodes must be responsibly resolved. most often it becomes problematic nodes in buildings windows, balconies and foundations junction with the outer walls (cappelletti et al. 2011, gea et al. 2011). gea h. et al. (2011) were analysing impact of balcony thermal bridges. their study showed that reducing the heat transfer through balcony slabs could benefit in terms of reducing the peak heating load by 6–16% and peak cooling load by 1–3% for scenarios simulated. the overall reduction on annual space heating energy consumption is 5–11% and less than 1% reduction for the annual space cooling energy consumption (gea et al. 2011). according to ibrahim m. et al. (2014) the study in france has been found that windows offset thermal bridges energy load constitutes around 2-8% of the total house load. applying the new coating, fig. 3 constructional nodes of linear thermal bridges: a) junction of outer wall and roof; b) the junction of outer wall and floor on the ground a b fig. 4 windows offset thermal bridge load percentage of the total cooling/heating (ibrahim et al. 2014) which thermal conductivity is 0.03-0.04 (w/m·k), reduces the windows offset thermal bridge load by about 24% to 50% (ibrahim et al. 2014). fig. 4 shows the windows offset thermal bridges energy load percentage of the total load of the house for 3 different cases: no coating on the thermal bridges, 1 cm coating is added, and 2 cm coating is added (ibrahim et al. 2014). journal of sustainable architecture and civil engineering 2016/2/15 50 in lithuania in project of energy performance classes a, a+ and a++ of buildings (their parts) must be submitted to linear thermal bridges design solutions and these bridges design heat transfer coefficients should be based on calculations (str 2.05.01:2013). thermal bridges may be defined as a part of the building envelope penetrated by materials with different thermal conductivity and/or with changed thickness/amount of materials used and/or with difference between internal and external areas, according to en iso 10211 (berggren and wall 2013). most of building energy simulation tools (bes) handle 1d heat transfer computation. the method consists in adding a term to take into account the 2d thermal bridge impact on the heat balance. integration of thermal bridges in bes depends on the simulation tools: variation of both the surface transmission coefficient of the wall, variation of the surface or specific transmission coefficient. they can be classified in two categories: _ point thermal bridges characterized by a punctual coefficient of transmission in w/k. they are caused by a singular point in the envelope (eg. in a local fixing system); _ linear thermal bridges characterized by a linear transmission coefficient ψ, w/m·k. they are associated to a length (intersection between two walls) (viot et al. 2015). the linear thermal transmittance of the thermal bridges () is calculated as in eq. (1): calculation of thermal bridges where l2d – the thermal coupling coefficient obtained from a 2-d calculation, uj – the thermal transmittance of the 1-d element j lj – the length of the 1-d element j (en iso 10211:2008). (5)�������������� � ��� − ∑ �� � �� �� ��� , measuring of lengths and areas may be done according to three different ways: internal, overall internal or external dimensions. the differences are shown in fig. 5 (berggren and wall 2013). are done many of studies examining thermal bridges calculation methods and modelling (quinten et al. 2016, berggren and wall 2013, martina et al. 2012, hoffman and schwartz 1980, asdrubali et al. 2012, ge and baba 2015). in this study linear thermal bridges were calculated with program „therm“. this program is designed to calculate two-dimensional temperature fields. ascione at al. (2013) were analysing finite element and finite volume methods of calculation and the accuracy of methods. their study showed that these methods of calculation are reliable. fig. 5 three different methods of measurement according to en iso 13789 (berggren and wall 2013). fig. 6 semi-detached building 51 journal of sustainable architecture and civil engineering 2016/2/15 the project of semi-detached building (fig. 6.), with 310,2 m2 of heating area was chosen to find out linear thermal bridges influence for building‘s energy consumption. the selected building’s envelope material, heating, ventilating and hot water systems meets „a” energy efficiency class requirements. as it is shown in table 1, biggest part of heat losses are through windows (20.43 kwh/(m2·k)) and the lowest part are through doors/gates (3.46 kwh/(m2·k)). it can be explained by analyzing the area’s and thermal transmittance coefficient relation. windows consist 99.02 m2 area and has 1 w/(m2·k) of thermal transmittance coefficient. while doors/gates with similar thermal transmittance coefficient but has only 22.75 m2 of area. walls and roof consist of bigger part of area, but has 10 times lower thermal transmittance coefficient. research object fig. 6 semi-detached building table 1 building envelope area, heat transfer coefficients and heat loss through building envelope partition name area, m2 thermal transmittance coefficient, w/(m2·k) heat losses of building‘s area, kwh/(m2·k) wall 346.3 0.12 8.29 roof 237.3 0,1 4.90 windows 99.02 1 20.43 doors / gates 22.75 1.00 / 1.32 3.46 floor 196.78 0.19 5.00 fig. 6 semi-detached building the thermal transmittance coefficient of linear thermal bridges can be effected by making different materials installing solutions. as it is shown in fig. 7, two external walls with different materials but with similar thermal transmittance coefficient were selected for calculations. the wall’s thermal transmittance coefficient of linear thermal bridge which consist of -0.05 w/(m·k) was made of gypsum plaster, cavity concrete blocks and neopor eps 70n. other wall was made of tiles, neopor eps 70n, silicate blocks and gypsum. the thermal transmittance coefficient of linear thermal bridge of this type of wall was -0.07 w/(m·k). as it is shown in fig. 8, two different foundation insulation types were analyzed. first example was insulated only with vertical insulation, second example was insulated with vertical and horizontal insulation. result of heat transfer coefficient is changing from 0.17 w/(m·k) to 0.03 w/(m·k). results journal of sustainable architecture and civil engineering 2016/2/15 52 fig. 7 calculation results of walls external corner different insulation cases fig. 8 calculation results of foundation different insulation cases 53 journal of sustainable architecture and civil engineering 2016/2/15 the difference between window position is shown in fig. 9. first example shows window installation directly into lintel, while second example shows window installation in insulating material. result of heat transfer coefficient is changing more than three times from 0.10 w/(m·k) to 0.03 w/(m·k). the difference between window position is shown in fig. 10. first example shows window installation directly into wall, while second example shows window installation in insulating material. result of heat transfer coefficient is changing more than four times from 0.09 w/(m·k) to 0.02 w/(m·k). fig. 9 calculation results of window and lintel different connection types fig. 10 calculation results of window and wall different connection types journal of sustainable architecture and civil engineering 2016/2/15 54 the difference between window position is shown in fig. 11. first example shows window installation directly on foundation, while second example shows window installation in insulating layer. result of thermal transmittance coefficient is changing from 0.22 w/(m·k) to 0.02 w/(m·k). the difference between balcony installation is shown in fig. 12. first example shows balcony connection to ceiling, while second example shows balcony connection directly to the wall. result of thermal transmittance coefficient of linear thermal bridge is changing from 0.13 w/(m·k) to 0.01 w/(m·k). fig. 11 calculation results of window and foundation different connection types fig. 12 calculation results of balcony different installation types 55 journal of sustainable architecture and civil engineering 2016/2/15 firstly, building‘s energy consumption calculations were made including heat losses through first version of linear thermal bridges. as it is shown in table 2, energy consumption of linear thermal bridges consist 8.6 % of total building‘s energy consumption. the minus and plus sign in thermal transmittance coefficient of linear thermal bridges helps to evaluate overlaps and shortages of thermal bridges length. as it is shown in table 3, the total balance is 38.79 w/k, which is 7.80 kwh/(m²·k). table 2 composition of building‘s energy consumption name of energy consumption energy consumption, kwh/(m2·k) % heat losses through building‘s walls 8.29 9.2 heat losses through building‘s roof 4.90 5.4 heat losses through building‘s floor 5.00 5.5 heat losses through building‘s windows 20.43 22.5 heat losses through building‘s doors 3.46 3.8 heat losses through building‘s linear thermal bridges 7.80 8.6 heat losses through building‘s ventilation system 5.35 5.9 total energy consumption of building‘s electricity systems 3.21 3.5 electricity consumption for building‘s lighting 0.90 1.0 heat energy consumption for the use of hot water 10.37 11.4 heat energy consumption of the building‘s heating systems 13.42 14.8 heat energy consumption of the building‘s cooling systems 7.47 8.2 total: 90.60 100 table 3 linear thermal bridges length, heat transfer coefficients and heat losses name of thermal bridge length, m thermal transmittance coefficient of liner thermal bridges ψ, w/(m·k) heat losses, w/k external corner of the wall 50.52 -0.05 -2.53 internal corner of the wall 23.12 0.02 0.46 wall / roof junction with parapet (external) 30.26 -0.02 -0.61 wall / roof junction with ridge (external) 22.8 -0.03 -0.68 wall / roof junction with ridge and parapet (external) 24.2 -0.03 -0.73 wall / garage roof junction (internal) 20.72 0.02 0.41 wall / garage roof junction (external) 12.98 -0.04 -0.52 wall and floor junction 69.9 0.17 11.88 wall and windows junction (insulated lintel) 53.86 0.1 5.39 wall and windows junction (insulated masonry) 150.5 0.09 13.55 windows and foundation junction(insulated foundation) 22.02 0.22 4.84 windows and garage roof junction(insulated slab) 1.5 0.17 0.26 wall and gate junction (insulated lintel) 5.36 0.1 0.54 wall and gate junction (insulated masonry) 9.48 0.09 0.85 garage floor and gates junction 5.36 0.47 2.52 wall and balcony junction 24.24 0.13 3.15 total: 38.78 journal of sustainable architecture and civil engineering 2016/2/15 56 secondly, building‘s energy consumption calculations were made including heat losses through second version linear thermal bridges. as it is shown in table 4, energy consumption of linear thermal bridges consist 1.5 % of total building‘s energy consumption. after evaluating second version linear thermal bridges, thermal transmittance coefficients of linear thermal bridges is shown in table 5, the total balance is 21.99 w/k, which is 1.22 kwh/(m²·k). table 4 composition of building‘s energy consumption name of energy consumption energy consumption, kwh/(m2·k) heat losses part of whole energy consumption heat losses through building‘s walls 7.70 9.6% heat losses through building‘s roof 4.55 5.7% heat losses through building‘s floor 4.64 5.8% heat losses through building‘s windows 18.98 23.6% heat losses through building‘s doors 3.21 4.0% heat losses through building‘s linear thermal bridges 1.22 1.5% heat losses through building‘s ventilation system 4.97 6.2% total energy consumption of building‘s electricity systems 3.21 4.0% electricity consumption for building‘s lighting 0.90 1.1% heat energy consumption for the use of hot water 10.37 12.9% heat energy consumption of the building‘s heating systems 11.00 13.7% heat energy consumption of the building‘s cooling systems 9.52 11.9% total: 80.27 100% table 5 linear thermal bridges length, heat transfer coefficients and heat losses name of thermal bridge length thermal transmittance coefficient of liner thermal bridges ψ, w/(m·k) heat losses, w/k external corner of the wall 50.52 -0.07 -3.54 internal corner of the wall 23.12 0.02 0.46 wall / roof junction with parapet (external) 30.26 -0.02 -0.61 wall / roof junction with ridge (external) 22.8 -0.03 -0.68 wall / roof junction with ridge and parapet (external) 24.2 -0.03 -0.73 wall / garage roof junction (internal) 20.72 0.02 0.41 wall / garage roof junction (external) 12.98 -0.04 -0.52 wall and floor junction 69.9 0.03 2.10 wall and windows junction (insulated lintel) 53.86 0.03 1.62 wall and windows junction (insulated masonry) 150.5 0.02 3.01 windows and foundation junction(insulated foundation) 22.02 0.02 0.44 windows and garage roof junction(insulated slab) 1.5 0.17 0.26 wall and gate junction (insulated lintel) 5.36 0.1 0.54 wall and gate junction (insulated masonry) 9.48 0.09 0.85 garage floor and gates junction 5.36 0.47 2.52 wall and balcony junction 24.24 0.01 0.24 total: 21.99 57 journal of sustainable architecture and civil engineering 2016/2/15 after literature analysis was done how linear thermal bridges affect building energy consumption it was found that inadequate building structures and combinations of materials selection can create preconditions to have greater heat loss than the envelopes with same thermal properties but different design solutions. foreign researchers found that certain solutions can reduce up to 11 percent thermal energy of the building. the analysis of the building in this paper showed that constructional solutions of a balcony, the foundation and the foundation with the showcase window had the greatest influence for the value of linear thermal bridges. replacement of balcony design solution passing through the slab through the outer wall into the design solution of the wooden frame attachment to an exterior wall reduced the value of linear thermal bridge 13 times (from 0.13 w/(m·k) up to 0.01 w/(m·k). belt foundation with a one-sided insulation up to 1.8 m deep change to 0.3 m recessed foundation insulation with a two-side reduced thermal bridges value of almost 6 times (from 0.17 w/(m·k) to 0.03 w/(m·k). showcase windows installation in the foundation thermal insulation layer reduces thermal bridges value almost 11 times (from 0.22 w/(m·k) to 0.02 w/(m·k)) compared with the installation of the floor structure. according to the requirements of eu directives from 2021, all new buildings will be built that do not consume energy (zero energy). according to the lithuanian construction requirements of technical regulations from the end of 2016, all newly built buildings will have to have at least “a” class energy performance of buildings. however, in order to design and build building of a high-energy performance class it is not enough to choose only regulatory requirements of the thermal properties or engineering system. the test of the buildings thermal performance, examined in the paper, showed that the correct solutions of linear thermal bridges reduced the building annual energy consumption of the building for heating 2.42 kwh/(m·k) and cooling to 2.05 kwh /(m·k), that is around 751 kwh/k and 636 kwh/k per year. conclusions european committee for standardization, en iso 10211:2008 thermal bridges in building construction– heat flows and surface temperatures–detailed calculations, 2007. quinten j., feldheim v. dynamic modelling of multidimensional thermal bridges in building envelopes: review of existing methods, application and new mixed method. energy and buildings, 2016; 284-293. berggren b., wall m. calculation of thermal bridges in (nordic) building envelopes risk of performance failure due to inconsistent use of methodology. energy and buildings, 2013; 2. viot h., sempey a., pauly m., mora l. comparison of different methods for calculating thermal bridges: application to wood-frame buildings. energy and buildings, 2015; 1-2. martina k., escudero c., erkorekaa a., flores i., salaa j.m. cork-based mortars for thermal bridges correction in a dwelling: thermal performance and cost evaluation. energy and buildings, 2012; 705-711. therm, v. 7.2, lbnl, http://windows.lbl.gov/software/therm/6/index.html. ascione f., bianco n., de masi r.f., de rossi f., vanoli g.p. simplified state space representation for evaluating thermal bridges in building: modelling, application and validation of a methodology. energy and buildings, 2013; 344-354. hoffman m., schwartz b. computation of steady and time-dependent temperature distribution for building elements: a general three-dimensional solution. energy and buildings, 1980; 63-72. cappelletti f., gasparella a., romagnoni p., baggio p. analysis of the influence of installation thermal bridges on windows performance: the case of clay block walls. energy and buildings, 2011; 1435–1442. gea h., mcclung v.r., zhangc s. impact of balcony thermal bridges on the overall thermal performance of multi-unit residential buildings: a case study. energy and buildings, 2011; 163–173. asdrubali f., baldinelli g., bianchi f. a quantitative methodology to evaluate thermal bridges in buildings. applied energy, 2012; 365–373. http://dx.doi. org/10.1016/j.apenergy.2011.12.054 ge h., baba f. dynamic effect of thermal bridges on the energy performance of a low-rise residential building. energy and buildings, 2015; 106–118. ibrahim m., biwole p. h., wurtz e., achard p. limiting windows offset thermal bridge losses using a new insulating coating. applied energy, 2014; 220-231. http://dx.doi.org/10.1016/j.apenergy.2014.02.043 str 2.05.01:2013 pastatų energinio naudingumo projektavimas ( str 2.05.01:2013 energy performance of buildings design). references journal of sustainable architecture and civil engineering 2016/2/15 58 aurelija levinskytė engineer laboratory of building physics at the institute of architecture and construction, ktu phd student kaunas university of technology, faculty of civil engineering and architecture main research area investigation of efficient energy use and assurance of microclimate condition in buildings, heat transfer and thermal insulation address tunelio st. 60, lt-44405, kaunas, lithuania tel. +370 629 40158 e-mail: aurelija.levinskyte@ktu.lt karolis banionis researcher laboratory of building physics at the institute of architecture and construction, ktu lector kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area energy efficiency and air permeability of buildings, heat transfer and thermal insulation, thermal impacts of solar radiation address tunelio st. 60, lt-44405, kaunas, lithuania tel. +370 37 350779 e-mail: karolis.banionis@ktu.lt about the authors valdemaras geležiūnas engineer laboratory of building physics at the institute of architecture and construction, ktu master’s degree student kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area energy efficiency and air permeability of buildings, use of waste water heat exchangers address tunelio st. 60, lt-44405, kaunas, lithuania tel. +370 641 81775 e-mail: valdemaras.geleziunas@ ktu.lt journal of sustainable architecture and civil engineering 2021/1/28 118 *corresponding author: imahamid@ymail.com effects of design quality on delay in residential construction projects received 2020/11/05 accepted after revision 2021/05/22 journal of sustainable architecture and civil engineering vol. 1 / no. 28 / 2021 pp. 118-129 doi 10.5755/j01.sace.28.1.20531 effects of design quality on delay in residential construction projects jsace 1/28 http://dx.doi.org/10.5755/j01.sace.28.1.20531 ibrahim mahamid* civil engineering department, faculty of engineering, university of prince mugrin, madinah, ksa and arab american university palestine introduction this study is conducted to establish the effect of design quality on project delay in building projects. it aims at: 1) investigating the major factors of design quality, 2) identifying the main delay factors in building projects, 2) establishing the relationship between design quality and delay in building projects. to achieve these objectives, a questionnaire survey is performed. seventeen (17) factors that might affect design quality, and 15 delay factors are listed in a questionnaire form. sixty (60) contractors and 40 consultants are asked to identify the severity of the identified factors. results indicate that the top factors affecting design quality are: delay in payments by client for design services, staff allocation for many projects at the same time, copying and modifying from previous work to minimize time and cost, tight design schedule, lack of designer knowledge with techniques and materials available in the market. the study also concludes that the top five delay factors include: payments delay, poor labor productivity, lack of skilled manpower, frequent change orders and rework. regression analysis for data collected from 36 building projects shows a good correlation between design quality and delay in projects. this study is the first one that addresses the problem of design quality in the west bank in palestine. furthermore, it is the first study that addresses the effect of design quality on project delay in palestine and the neighboring countries. it is hoped to be helpful for researchers and professionals to understand the impact of design quality on schedule delay. keywords: buildings, delay, design, quality, time overrun. construction industry has a major impact on the economic improvement for any country. it involves many resources, namely: finance, machinery, raw materials, technology and human resource. it also involves many parties such as: clients, consultants, designers, contractors, subcontractors, and suppliers. however, the management process of construction projects is complicated due to many resources and parties involved in it. enshassi et al. (2003) stated that “the increasing complexity of infrastructure projects and the environment within which they are constructed place greater demand on construction managers to deliver projects on time, within the planned budget and with high quality”. previous studies revealed that most of construction projects completed with schedule delay. for instance, omoregie and radford (2006) concluded that the average time deviation in construction projects in nigeria is 188%. faridi and el-sayegh (2006) found that 50% of construction projects in uae completed with time overrun. assaf and alhejji (2006) indicated that 70% of construction projects implemented in saudi arabia completed with schedule delay. mahamid et al. (2012) revealed that 95% of highway construction projects in palestine completed with delay with average value of 37%. schedule delay has severe impact on project success. it is one of the main factors result in project failure in construction projects. it 119 journal of sustainable architecture and civil engineering 2021/1/28 causes cost overrun, disputes, conflicts and quality deficiencies on site which negatively affect the relation between construction parties, equally the project performance. design plays a major role in construction projects. design quality influences the overall project performance. it also has main effect on project performance (couto, 2012). improper planning and design management during design phase leads to project failure (williams and johnson, 2014). pandit (2015) stated that “problems during design development contribute significantly to delays”. mahamid and bruland (2011) linked cost overrun of highway projects to lack of time for estimates, mistakes in drawings, changes in design, and unclear specifications. in their study, they concluded that out of 51 identified factors, the top five factors affecting cost overrun include two factors that are related to design, namely: incomplete drawing and lack of designers’ experience. durdyev et al. (2010) found that frequent design changes contribute to cost overrun and project delay in building projects. kpamma and adjei-kumi (2011) concluded that the waste is generated during design phase and consultants are unable to manage it. it has high impact on project delay and cost overrun. gobang et al. (2020) attributes time overrun of highway projects to delay in decision making by the client, design mistakes and errors, frequent design changes by client and consultant, and approvals from stakeholders. out of total 36 factors identified in gobang’s et al. (2020) study, the top four factors influencing time overrun include two factors that are related to design, namely: design errors and design changes. literature review show that very little or no studies have investigated the relationship between design quality and schedule delay in building projects. this study is the first one that addresses the problem of design quality in the west bank in palestine. furthermore, it is the first study that addresses the effect of design quality on project delay in palestine and the neighboring countries. this paper aims at: (1) identifying factors of design quality that may have significant impact on project results, (2) identifying factors affecting schedule delay, (3) establishing the relationship between design quality and schedule delay. construction parties need to have a full list of factors that might affect project results and to understand the relation between these factors, and therefore prioritize their efforts to eliminate them and to improve performance in construction projects. factors affecting design quality in building projects the design quality has a main impact on project performance and efficiency in construction projects. poor standards of design quality contribute to poor performance in construction projects (abdelaziz, 2009). a study conducted in gaza found that the most significant factors affecting design quality in construction projects are: poor skills of consultant’s staff, lack of time allowed for checking of design documents, lack of experience, unfamiliarity of designers with construction techniques used in the project and absence of good design manager. on the other hand, the study concluded that the most occurred factors are: low design fees, selection of designers with lowest price, allocation of staff to many projects, frequent changes by client and unwillingness of clients to pay fees for design of high-quality (abdelaziz, 2009). love et al. (2006) revealed that “mistakes in design” is a major factor that affects rework cost in construction projects. pandit (2015) addressed the main factors influencing design quality in construction projects. he concluded that the top factors include: parameters of structural design, soil tests, control of quality, survey works, and parameter of architectural design. design mistakes lead to rework which influences the overall performance in building projects (li and taylor, 2014). to reduce the effect of design rework in construction projects, li and taylor (2014) recommended strategies to enhance design quality. lopez and love (2012) investigated 139 construction projects. they concluded that the cost of design mistakes is 6.85% of the total project cost. couto (2012) concluded that omissions and errors in designs result in claims and disputes in projects. durdyev et al. (2010) indicated that the main factors affecting design management are: lack of site investigation and frequent changes in design. ali et al. (2012) stated previous studies journal of sustainable architecture and civil engineering 2021/1/28 120 that design deficiencies is one of the significant factors result in cost overrun, schedule delay and quality deviations in construction projects. in a study conducted in jordan, it is found that poor design brief and errors in parameters of design are main factors affecting time overrun in public construction projects (sweis’s, 2013). factors affecting schedule delay in building projects schedule delay is defined as “the time difference between the actual completion time and the estimated completion time, agreed by and between the client and the contractor during signing of the contract” mahamid et al. (2012). the problem of schedule delay in one of the main problems in construction industry (kaliba et al., 2009; mahamid, 2017b; santoso and soeng, 2016). mahamid (2017a) found that the average of delay in highway construction projects in saudi arabia is 58.24%, ranging from 2% to 172%. al-najjar (2008) addressed the main delay factors in building projects in gaza strip, they are: strikes, political problems, shortage of construction materials, cash problems, improper site management, economic problems, unavailable equipment, tool shortage and payments delay by the owner. kaliba et al. (2009) identified the main causes of time overrun in construction projects, namely: payments delay, financial problems, frequent changes, lack in equipment, design mistakes, conflicts and disputes, and strikes. in malaysia, memon et al. (2012) indicated that the significant delay factors include: design deficiencies, financial difficulties, poor management, improper site management and communication technology. mahamid et al. (2012) addressed delay factors in highway projects in palestine. contractors concluded that the top five factors are: segmentation, political situation, payment delay, delay in decision making and poor productivity. in the same study, the consultants found that the main factors are: political conditions, limitation on movement, lowest bid price strategy, lack in equipment and unreasonable schedule. among various factors that causes schedule delay in construction projects, financial difficulties, improper planning and management, inadequate experience, and unavailability of labors top the list (memon et al., 2014). mahamid et al. (2015) conducted a study in saudi arabia to identify the main factors contributing to project delay in highway construction projects. they concluded that the top factors are: bid awarding policy, variations in specifications, contract management, tight time for bidding, changes in materials price, design variations, improper planning, lack of skilled labors, poor productivity and rework. msafiri (2015) addressed delay causes in building projects in kenya. the top factors are: delay in payments by client, lack of planning, late decision and weather effects. al-hazim and abusalem (2015) concluded that terrain and weather are the significant factors affecting schedule delay in construction projects. santoso and soeng (2016) found that the significant contributor to project delay are: bidding policy, inefficient equipment, site management, terrain, payments delay and poor labor productivity. mahamid (2017b) linked schedule delay in highway projects with the physical characteristics of the project. good correlation between delay and ground conditions is addressed. furthermore, mahamid (2017a) study revealed the top delay factors, they are: poor planning, lack of productivity, rework, poor experience and additional works. the study indicated that project delay contributes to severe problem on site such as: cost deviations, conflicts, disputes, arbitration, litigation, and quality deviations. gobang et al. (2020) revealed that the main factors affecting construction delay in saudi arabia are: delay in decision making by the client, design mistakes and errors, frequent design changes by client and consultant, and approvals from stakeholders. in summary, literature review shows that little studies were conducted to address the problem of deign quality in construction projects. therefore, more studies should be conducted to address this important area in construction industry. while many studies were investigated the main factors of schedule delay in construction projects. however, this is the first study that addresses 121 journal of sustainable architecture and civil engineering 2021/1/28 the effects of design quality on project delay. therefore, it is important and could be helpful for researchers and professionals as well. the study pays the attention of construction parties to the effects of design quality on project delay, so they can improve performance of construction projects. it is very clear that better design quality could positively affect project outcomes. research methods when the study objectives set, the following steps are followed to achieve them: 1. literature review is done to find out the factors affecting design quality and schedule delay are identified. seventeen (17) influencing design quality and 15 factors affecting schedule delay are identified. 2. a questionnaire is designed. it includes 3 parts: part 1 asks about respondent and company, part 2 includes the list of factors affecting design quality, and part 3 included the list of factors affecting schedule delay. participants are asked to rank the listed factors using a 5-point linkert scale from 1 (very low severity) to 5 (very high severity). 3. pilot study is conducted distribution the questionnaire. the pilot study aims to check the validity of the questions from the viewpoint of 3 local experts in construction projects. the experts show that the questions are suitable to achieve the study objectives and slight modifications made by them. 4. distribution and collection: in this step, the questionnaire is distributed for the target population in this study. the target population are consultants and contractors that are specialized in residential building construction. questionnaire are distributed and collected using the following methods: hand distribution and collection, fax and email. 5. data analysis: statistical package for the social science (spss) is used to analyze the data. average score for each factor is used to rank the identified factors. to check the correlation between the respondents, spearman rank correlation is used. 6. after ranking the identified factors, factor analysis is used to find out the significant factors affecting design quality. only factors with eigen value ≥ 1.0 (significant factors) are retained. after identifying the significant factors affecting design quality, a questionnaire is sent to the participants to identify the effect of these factors on schedule delay. the participants show the effect of these factors using a scale from 0 (no effect) to 4 (extreme effect). 7. case study: to develop a mathematical model that shows the relation between design quality and schedule delay, a case study is conducted using data from 36 building projects (details are in section 4.5). study population the target population are: 1) consultants who have valid membership in palestinian engineers association, and have experience in building construction projects, 2) contractors who have membership in the palestinian contractors union (pcu. total of 185 registered contractors of grade 1, grade 2 and grade 3, and 90 consultants with valid membership are targeted. to calculate the representative sample size, equation 1 is used (emory, 1980): n = (ts/d)2 / [1 + (ts/d)2/n] (1) where: n – size of sample; n – population sample; t – abscissa of the normal curve that cuts of an area of α – 0.01 at the tails (t = 2); d – expected error in the estimate (d = 0.01); s – max. standard deviation in proportion of estimation – p × q (at p = 0.5 and q = 1 – p = 0.5) table 1 shows the calculation of a representative sample. the calculation is continued until the difference between n and n-1 is small journal of sustainable architecture and civil engineering 2021/1/28 122 population # 1 (contractors) population # 2 (consultants) n0 185 90 n1 84 57 n2 55 42 n3 41 33 n4 33 27 n5 27 23 n6 23 20 n7 20 18 table 1 calculation of a representative sample fig. 1 positions of the respondents 10,40% 16,60% 28,30% 25,70% 11,50% 7,50% project manager construction manager design engineer site engineer office engineer others table 1 shows that the representative samples for contractors and consultants are 23 and 20, respectively. to be more accurate, the questionnaire is randomly distributed to 60 contractors and 40 consultants. the contractors and consultants are selected from an available list. eighty-eight (88) questionnaires are received (88 %) as follows: 52 (86.67%) from contractors, and 36 (90%) from consultants. the participants have average experience of more than 10 years in residential projects. regarding the positions of the respondents, fig. 1 shows that the respondents results and discussion experienced office engineers are (10.4%), site engineers (25.7%), designers (28.3%), construction manager (16.6%), project managers (10.4%) and others (7.5%). spearman rank correlation spearman rank correlation test measures the correlation between contractors and consultants on the severity of design quality factors and schedule delay factors. the value of spearman correlation (rs) is ranging from (-1) to (+1), a value of (+1) shows a full positive correlation and a value of (-1) indicates a full negative correlation. values in between shows a correlation less than perfect. equation 2 used to calculate the value of rs (harnett and murphy, 1975): rs = 1 – [6*∑d 2/(n3 – n)] (2) where: rs – coefficient of spearman rank correlation; d – difference between ranks on one variable and ranks on the other variable; n – number of factors ranking of factors of schedule delay in building construction projects fifteen (15) factors that might affect project delay are identified through previous studies and feedback from experts in building projects. contractors and consultants used a 5-point likert scale to recognize the rank of the identified factors. table 2 shows that the overall ranking identifies 123 journal of sustainable architecture and civil engineering 2021/1/28 table 2 ranking of factors affecting delay in residential building projects factor consultants contractors overall s.i rank s.i rank s.i rank payments delay 4.16 1 4.25 1 4.21 1 poor labor productivity 4.07 2 4.12 3 4.10 2 lack of skilled manpower 3.95 3 4.17 2 4.08 3 frequent changes orders 3.92 4 3.99 5 3.96 4 rework 3.83 5 4.03 4 3.94 5 lack of coordination between construction parties 3.69 6 3.90 6 3.82 6 poor relationship between managers and labors 3.45 8 3.78 7 3.64 7 contractor poor financial conditions 3.59 7 3.65 8 3.62 8 mistakes in design 3.25 10 3.64 9 3.48 9 lack of contractor experience 3.30 9 3.58 11 3.47 10 number of projects going at the same time 3.06 11 3.62 10 3.39 11 disputes on site 2.96 12 3.38 13 3.21 12 poor site management 2.68 15 3.55 12 3.19 13 additional work 2.73 14 3.29 14 3.06 14 effects of weather 2.82 13 3.16 15 3.02 15 “payments delay”, “poor labor productivity”, “lack of skilled manpower”, “frequent change orders” and “rework” are the top factors affecting schedule delay. these factors are identified by both contractors and consultants as major factors but in different ranks. “payments delay” leads to many problems on site that negatively affect the smooth progress of the projects. these problems include poor productivity, poor motivation, bad relation between construction parties, conflicts and disputes. this result is in line with al-najjar (2008), kaliba et al. (2009) and mahamid et al. (2012). “poor labor productivity” indicates that the activity takes more time than planned. many factors may lead to poor productivity on site such as payment delay, low wages, poor skills, project complexity ...etc. it should be noted that construction labor cost percentage is between 20 and 40% of total cost which means that labors have important role in building projects and the success of project is directly affected by their productivity. therefore, labors should be motivated to improve their productivity. this conclusion agrees with mahamid (2017a), santoso and soeng (2016) and mahamid et al. (2012). “lack of skilled manpower” is a main problem in palestinian construction market. this is due to low wages that the labors get in comparison with what they obtained in israeli construction market. therefore, the high skilled labors prefer to work in israel to obtain better wages. poor skills lead to many problems in building projects such as poor productivity, bad quality, rework, conflicts and disputes. this result agrees with memon et al. (2014) and mahamid et al. (2015). “frequent change orders” and “rework” indicate that more time and efforts are required to complete the same activity. these results are in line with kaliba et al. (2009), mahamid et al. (2015) and mahamid (2017a). ranking of factor affecting design quality seventeen (17) factors affecting design quality in building projects are identified through literatures and opinions of local construction experts. respondents use 5-point likert scale rank the identified factors. consultants indicate that the main 5 factors affecting design quality are: delay in payments journal of sustainable architecture and civil engineering 2021/1/28 124 table 3 ranking of design quality factors in building construction projects factor consultants contractors overall s.i rank s.i rank s.i rank delay in payments by client for design services 4.32 1 4.18 1 4.24 1 staff allocation for many projects at the same time 4.21 2 4.06 3 4.12 2 copying and modifying from previous work to minimize time and cost 4.07 4 4.09 2 4.08 3 tight design schedule 4.11 3 3.97 4 4.03 4 lack of designer knowledge with techniques and materials available in the market 3.93 6 3.76 5 3.81 5 inadequate time for checking of design documents 3.79 8 3.68 6 3.73 6 selection of designers based on lowest price 4.01 5 3.46 8 3.69 7 lack of consultant experience 3.80 7 3.38 9 3.55 8 lack of skilled design managers 3.38 9 3.62 7 3.52 9 change in project requirements by client at later stages 3.40 10 3.24 10 3.31 10 reduced design fees levels 3.56 11 3.11 11 3.29 11 inadequate design reviews with relevant parties 3.34 12 2.92 13 3.09 12 inadequate design coordination between design disciplines 3.02 15 2.96 12 2.98 13 project complexity 3.21 13 2.77 15 2.95 14 insufficient information from the client 3.17 14 2.64 17 2.86 15 ineffective use of new technology 2.83 16 2.87 14 2.85 16 lack in number of staff in each specialization (architect, structural… etc.) 2.74 17 2.73 16 2.73 17 by client for design services, staff allocation for many projects at the same time, tight design schedule, copying and modifying from previous work to minimize time and cost and selection of designers based on lowest price. contractors input shows that the major factors affecting design quality in building projects are: delay in payments by client for design services, copying and modifying from previous work to minimize time and cost, staff allocation for many projects at the same time, tight design schedule and lack of designer knowledge with techniques and materials available in the market. overall ranking finds that the top five factors are: delay in payments by client for design services, staff allocation for many projects at the same time, copying and modifying from previous work to minimize time and cost, tight design schedule, lack of designer knowledge with techniques and materials available in the market. only two factors out of the top five factors revealed by previous studies as significant factors affecting design quality, namely: “staff allocation for many projects at the same time” and “lack of designer knowledge with techniques and materials available in the market”. these factors are concluded in a study conducted by abdelaziz (2009). factor analysis is used to conclude the top significant factors affecting design quality in building projects. all factors that have eigen value ≥ 1.0 (significant factors) are retained. only 4 factors with 125 journal of sustainable architecture and civil engineering 2021/1/28 significant factors affecting design quality (eigen values ≥ 1.0) effect on schedule delay no effect low effect moderate effect high effect extreme effect relative index delay in payments by client for design services 0 1.85 9.8 60.15 28.2 0.64 copying and modifying from previous work to minimize time and cost 0 3.1 13.6 60.2 23.1 0.61 tight design schedule 0 5.6 20.90 56.8 16.7 0.57 staff allocation for many projects at the same time 0 8.4 22.6 51.1 17.9 0.56 table 4 relationship between design quality and schedule delay in building projects eigen value ≥ 1 are identified, namely: delay in payments by client for design services, staff allocation for many projects at the same time, copying and modifying from previous work to minimize time and cost, and tight design schedule. the cumulative variance of the significant factors is 75.11%. the 1st ranked factor, delay in payments by client for design services, has eigen value of 5.42, while the 4th ranked factor, tight design schedule, has eigen value of 1.31. spearman rank correlation equation (2) is used to check the correlation between contractors and consultants on the severity of design quality factors and delay factors. result shows a good correlation between contractors and consultants on the severity of design quality factors (rs = 0.79) and schedule delay factors (rs = 0.83), so the study is reliable. design quality and schedule delay in building construction projects table 4 investigates the effect of significant design quality factors on schedule delay from the point of view of the targeted contractors and consultants. it shows the effect of these factors in relative ranks. according to 88% of respondents, “delay in payments by client for design services” is the factor that has the highest effect on schedule delay. delay of payment by the clients affects the ability of design office to complete its work smoothly. it also might affect the motivation of designers which negatively affect their morale and productivity. “copying and modifying from previous work to minimize time and cost” ranked in the second position with relative index of value 0.61. due to low design fees, designers use designs from previous projects to save cost and time. on the contrary, copying and modifying from previous design works lead to mistakes in design that lead to change orders and rework during construction phase which delay the project. closely “tight design schedule” and “staff allocation for many projects at the same time” ranked in the third and fourth positions with relative index of value 0.57 and 0.56, respectively. tight schedule gives designers less time for checking of design and contract documents. this leads to more and more mistakes in design which leads to time overrun. “staff allocation for many projects at the same time” leads for struggling with how to manage design-related tasks which affect design quality and designer productivity. result shows that the significant factors affecting design quality have high impact on schedule delay, so these factors should be controlled to improve project success in terms of time, cost and quality. case study this study aims at establishing the effect of design quality on delay in residential building projects. to achieve this objective, data from 35 building projects executed in the west bank in palestine are gathered. regression linear analysis is decided to be used to establish the relation between the conjournal of sustainable architecture and civil engineering 2021/1/28 126 y = 2.3802x + 7.8384 r² = 0.7123 0 5 10 15 20 25 30 35 40 45 50 55 0 4 8 12 16 20 d el ay (% ) number of design changes fig. 2 relation between design changes and schedule delay in building projects table 5 results of statistics for relation between design changes and schedule delay regression analysis results multiple r 0.84 r2 0.71 adjusted r2 0.7 f 76.19 observations 35 coefficients t stat p-value intercept 7.84 2.26 0.030433 design changes (#) 2.38 8.72 7.41e-10 sidered variables. this is because it is well-defined approach and widely used to describe the relation between dependent and independent variables (mahamid, 2020). in this case study, number of design changes is defined as an indicator for design quality and schedule delay is defined “as the time difference between the actual completion time and the planned completion time” (mahamid et al., 2012). data collected from available records in consultant offices and contracting firms in the west bank in palestine. all considered projects are residential buildings with 2-4 floors executed in the west bank in the period between 2015 and 2020. to establish the regression model, number of design changes is considered as the independent variable (x) and schedule delay in per cent is considered as the dependent variable (y). results indicate that the average of schedule delay = 37% and the average number of design changes = 12. fig. 2 and results obtained in table 5 show a good linear relation between the dependent and independent variables (r2 = 0.71, f(1, 34) = 76.19, p < 0.05). equation (3) presents the established model. the coefficient of design quality shows the magnitude of change in schedule delay due to changes in design which is 2.38. so, if design changes increase in one unit, schedule delay will increase in 2.38 units. the intercept (constant) is 7.84. y = 2.83x + 7.84 (3) where: y – schedule delay in per cent, x – number of design changes. 127 journal of sustainable architecture and civil engineering 2021/1/28 conclusion this study concludes that among the different factors that causes schedule delay, payments delay, poor labor productivity, lack of skilled manpower, frequent change orders and rework top the list. it also shows that among various factors affecting design quality, delay in payments by client for design services, staff allocation for many projects at the same time, copying and modifying from previous work to minimize time and cost, tight design schedule lack of designer knowledge with techniques and materials available in the market are the most significant factors. spearman rank correlation test indicates a good agreement between contractors and consultants on the severity of schedule delay factors (rs = 0.83) and factors of design quality (rs = 0.79). therefore, the study is reliable. factor analysis results indicate four major factors affecting design quality, namely: delay in payments by client for design services, staff allocation for many projects at the same time, copying and modifying from previous work to minimize time and cost, and tight design schedule. respondents recognize that the significant factors of design quality have high impact on schedule delay, so these factors should be controlled and minimized by project management team in construction projects to enhance the overall performance. the predictive model established using data from 35 building projects executed in the west bank in palestine implies a significant relationship between design quality and schedule delay. equally, the relationship is directly proportional: more design changes occur, more delay will happen. more precisely, the model indicates that a unit increase (or decrease) in design changes results in 2.38 units increase (or decrease) in schedule delay. based on the output of this study, the following recommendations are suggested to improve design quality and to minimize schedule delay in building construction projects in palestine. a. clients should fund the project effectively and should pay for design services on time. this is important to avoid unnecessary delays. b. contractors and sub-contractors should train labors to improve their skills which will improve their productivity and reduce project delay. c. enough time should be allowed for designers, so they can check and correlate all the information on all design documents. this will reduce mistakes in design and eventually project delay. d. enough staff should be appointed by deign offices. designers should not be allocated for many projects because it will affect their ability to manage design-related tasks. e. suitable time frame should be given for planning designing, and bidding. all documents prepared in planning and design phases should be reviewed and checked to avoid any mistake. it will be very helpful in reducing change orders and rework during construction phase. references abdelaziz, s. 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(2017a). schedule delay in the ksa road construction projects: size, estimate, determinants, and effects. international journal of architecture, engineering and construction vol 6, no 3, 51-58. https://doi. org/10.7492/ijaec.2017.017 mahamid, i. (2017b). analysis of schedule deviations in road construction projects and the effects of project physical characteristics. journal of financial management of property and construction, vol 22, issue 2, pp.192-210. https://doi.org/10.1108/ jfmpc-07-2016-0031 mahamid, i. (2020). study of relationship between rework and labor productivity in building construction projects. journal of construction. 19 (1), 30 40. https://doi.org/10.7764/rdlc.19.1.30-41 mahamid, i. and bruland, a. (2011). cost overrun causes in road construction projects: consultants’ perspective. 2nd international conference on construction and project management ipedr vol.15 (vol. 15, pp. 6-10). singapore: iacsit press. mahamid, i.; al-ghonamy , a.; and aichouni, a. (2015). risk matrix for delay causes in construction projects in saudi arabia. research journal of applied sciences, engineering and technology 9(8): 665-670. https:// doi.org/10.19026/rjaset.9.1452 mahamid, i.; bruland, a.; and dmaidi, n. (2012). causes of delay in road construction projects. journal of management in engineering, 28(3), 300-310. https://doi. org/10.1061/(asce)me.1943-5479.0000096 memon, a.; rahman, i.; akram, m.; and ali, n. (2014). significant factors causing time overrun in construction projects of peninsular malaysia. modern applied science, 8(4), 16. https://doi.org/10.5539/mas.v8n4p16 memon, a.; rahman, i.; and azis, a. (2012). time and cost performance in construction projects in southern and central regions of peninsular malaysia. international journal of advances in applied sciences, vol. 1 no. 1, pp. 45-52. https://doi. org/10.11591/ijaas.v1i1.537 msafiri, a. (2015). an investigation into factors causing delays in road construction projects in kenya. american journal of civil engineering, 3 (3) , pp. 51-63. https://doi.org/10.11648/j.ajce.20150303.11 omoregie, a. and radford, d. (2006). infrastructure delays and cost escalation: causes and effects in nigeria. proceedings of the 6th international postgraduate research conference in the built and human environment, international council for research and innovation in building and construction. pandit, d. (2015). factors affecting construction project design development: a perspective from india. international journal of construction supply chain management. 5 (2), 52-67. https://doi.org/10.14424/ ijcscm502015-52-67 santoso, d. and soeng, s. (2016). analyzing delays of road construction projects in cambodia: causes and effects. journal of management engineering, vol. 31 no. 6, doi: 10.1061/(asce)me.19435479.0000467, 05016020. https://doi.org/10.1061/(asce)me.1943-5479.0000467 129 journal of sustainable architecture and civil engineering 2021/1/28 about the author this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/ ). sweis, g. (2013). factors affecting time overruns in public construction projects: the case of jordan. international journal of business and management, 8(23), 120-129. https://doi.org/10.5539/ijbm. v8n23p120 williams, c. and johnson, p. (2013). standards of professional practice for design management. journal of professional issues in engineering education and practice, 140(2), doi: 10.1061/(asce)ei.19435541.0000190, 04013011. https://doi.org/10.1061/ (asce)ei.1943-5541.0000190 ibrahim mahamid professor civil engineering department, faculty of engineering, university of prince mugrin. main research area cost and time estimating, project evaluation, risk and uncertainty management, construction contracts, productivity improvement, bim and lean construction management address university of prince mugrin, king abdullah road, madinah, p.o box : 40202, saudi arabia tel.: 00966536659056 e-mail: imahamid@ymail.com journal of sustainable architecture and civil engineering 2016/3/16 108 *corresponding author: chenjiajian@fosu.edu.cn improving particle size distribution in cement paste by blending with superfine cement http://dx.doi.org/10.5755/j01.sace.16.3.16273 p.l. ng department of civil engineering, the university of hong kong, pokfulam, hong kong, china faculty of civil engineering, vilnius gediminas technical university sauletekio ave. 11, vilnius lt-10223, lithuania j.j. chen* department of civil engineering, foshan university, 18 jiangwan road, foshan, guangdong, china a.k.h. kwan department of civil engineering, the university of hong kong, pokfulam, hong kong, china received 2016/08/21 accepted after revision 2016/10/10 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 108-120 doi 10.5755/j01.sace.16.3.16273 © kaunas university of technology improving particle size distribution in cement paste by blending with superfine cement jsace 3/16 the rheological and mechanical performance of cement paste is closely related to its packing density, which may be optimized by improving the particle size distribution in the paste mix. in this study, the authors propose modifications to the existing mathematical equations of particle size distribution. the new equation of optimal particle size distribution so formulated is verified experimentally. a series of cement paste having different water/cementitious materials (w/cm) ratios were produced by blending ordinary portland cement (opc) with varying contents of superfine cement (sfc). the particle size distributions of the blended paste mixes were compared with the proposed equation. the packing density of paste mixes was measured using the wet packing test method, and the flowability, rheological properties, and compressive strength of the paste mixes were tested. it is found, that the particle size distribution in cement paste can be improved by blending with sfc, which can lead to enhancement in packing density, flowability, rheology and strength. the authors opine that the proposed equation of particle size distribution may be applied for mix design optimization of cementitious paste, including cementitious grout and the paste phase in mortar and concrete. keywords: packing density, particle size distribution, paste, rheology, superfine cement. cementitious paste is a mixture of water and cementitious materials. in a paste mix, the water must be sufficient to fill up the voids between solid ingredients, as any unfilled voids would become air voids and eventually porosity in the hardened paste (kwan and wong 2008). the rheological and mechanical performance of cementitious paste is closely related to its packing density. in fresh state, a high packing density would generally require less water to fill up the voids in the cementitious matrix. therefore, for the same water/cementitious materials (w/cm) ratio, a greater amount of excess water (i.e. water in excess of that needed to fill the voids) would be available to lubricate the solid particles, thus improving the flowability and rheological performance. alternatively, for the same flowability performance, the w/cm ratio may be reduced to improve the strength of hardened paste. introduction 109 journal of sustainable architecture and civil engineering 2016/3/16 theoretically, the packing density could be optimized by improving the particle size distribution in the paste mix. an optimal particle size distribution should be a continuous one such that the finer particles could fill into the voids between larger particles and reduce the overall volume of voids. this concept has been incorporated in devising mathematical equations of ideal particle size distributions for packing of aggregates for mortar and concrete (andreasen and andersen 1930, furnas 1931). however, there has been a lack of well-proven particle size distribution model that could cater for the powder phase, which may be classified as finer than 75 μm in size. in fact, there is a common misunderstanding that the fines portion (which may be taken as in the size range of powder) in fine aggregate is always unfavourable to the quality of aggregate and hence the quality of mortar and concrete. in actual fact, the presence of appropriate proportions of fines can be beneficial to optimizing the packing density of fine aggregates (kwan et al. 2014). moreover, to improve the packing density of paste, the role of powders should be duly considered in the particle size distribution model. as opposed to the continuous particle size distribution, in conventional cement concrete, the solid ingredients including cement grain, fine aggregate and coarse aggregate are not continuously graded. there are gaps in the size ranges of roughly 50 to 500 μm (lying between cement and fine aggregate) and smaller than 5 μm (finer than cement) (chen 2012). these gaps may be filled by fillers of appropriate sizes. in connection to this, experimental investigations have demonstrated the positive role of fillers (including fines as part of fillers) in mortar and concrete (chen et al. 2012). for conventional cement paste, there exists a gap in the size range of roughly 5 μm and below, which may be filled by appropriate fillers for improved particle size distributions in the paste. however, as pointed out in the above, due to a lack of established particle size distribution model to cater for the powder phase, the optimization of packing density of cementitious paste mix is usually performed by trial and error. to enable optimizing the packing density of cementitious paste by a scientific approach, a new equation of optimal particle size distribution is developed herein. the equation is verified by an experimental programme encompassing a series of cementitious paste produced by blending ordinary portland cement (opc) and superfine cement (sfc) in different proportions. details of the mathematical formulations and experimental investigations are reported hereunder. the strategy of optimizing the particle size distribution to achieve maximum packing density had been adopted in the past for mortar and ceramic production. a number of ideal particle size distribution equations had been proposed. early in the 30’s in last century, andreasen and andersen (1930) put forward the below equation of ideal particle size distribution: optimization of particle size distributionwhere cpft is the “cumulative percentage finer than”, d is the particle size, dl is the largest particle size, and m is a distribution index or distribution mod(1)%100×      = m ld d cpft ulus. equation (1) is commonly referred to as andreasen’s equation. it was validated experimentally by andreasen and andersen (1930), who suggested that the value of m should be between 0.33 and 0.50 for maximum packing density. by plotting cpft against d with both axes drawn in logarithmic scale, the andreasen’s equation is represented by a straight line in the log-log plot. where ds is the smallest particle size, r is a distribution coefficient, and other symbols have the same meaning as in equation (1). (2) furnas (1931) and anderegg (1931) investigated the packing of aggregates for mortar, and revised the mathematical formulation with consideration of the influence of smallest particle size on the particle size distribution. the ideal particle size distribution proposed by furnas (1931) is given by: %100 lnln lnln ×         − − = sl s dd dd rr rr cpft journal of sustainable architecture and civil engineering 2016/3/16 110 funk and dinger (1994) modified andreasen’s equation for applications in ceramic manufacturing. they advocated the strategy of predictive process control to maximize packing density by following the optimal particle size distribution (dinger and funk 1992, 1996, 1997, dinger 2001, 2002). for this purpose, the below equation was proposed (funk and dinger 1994): (3) equation (3) is often referred to as modified andreasen’s equation. by means of numerical simulation, funk and dinger (1994) claimed that if the particles follow a continuous grading until down to an infinitely small particle size, then 100% packing %100×         − − = m s m l m s m dd dd cpft density (or 0% porosity) can be achieved when the distribution modulus m is smaller than or equal to 0.37. however, it is impossible to have infinitely small particles in reality. the role of smallest particle size ds should be duly considered in the particle size distribution model. in this regard, the influence of ds was ignored in andreasen’s equation but it was taken into account by furnas (1931) and funk and dinger (1994). equations (1) to (3) above follow the principle of geometric similarity. in other words, if all the particles are enlarged or shrunk by the same ratio, the resulting packing density would remain unchanged. besides, it can be shown mathematically that equation (2) and equation (3) are equivalent with the only difference of a constant of proportionality. in particular, if m is taken as ln(r), or r is taken as em, both equations would become identical. among various particle size distribution models, the modified andreasen’s equation has been applied to the production control of high-performance concrete (hpc) and yielded interim success (zheng and kwan 2006). in contrast to concrete and mortar, the aggregate phase is omitted in paste, while the powder phase in blended paste mixes exerts substantial influence on the packing of solids. as such, alterations to the particle size distribution model would be necessitated. herein, the authors propose modifications to the existing mathematical equations. the new equation is given by equation (4), in which p and q are modified distribution moduli, ζ is a dimensionless parameter as defined in equation (5), and other symbols have the same meaning as previously defined. the proposed equation of optimal particle size distribution is experimentally verified with cementitious paste mixes produced from blending varying contents of ordinary portland cement (opc) and superfine cement (sfc). the experimental programme is described below. the opc was of strength class 52.5n complying with european standard en 197-1: 2011. the sfc was produced in france and it contained 80% slag. the solid densities of the opc and sfc were measured to be 3112 kg/m3 and 2940 kg/m3, respectively. with the use of laser diffraction particle size analyzer, the particle size distributions of opc and sfc were measured as plotted in fig. 1. based on the particle size distributions so obtained, the mean particle sizes of opc and sfc were evaluated respectively to be 12.4 μm and 3.1 μm, whereas their specific surface areas were evaluated respectively to be 1.014×106 m2/m3 (equivalent to 326 m2/kg) and 2.293×106 m2/m3 (equivalent to 780 m2/kg). a polycarboxylate ether-based superplasticizer (sp) was added to the paste mixes for better dispersion of the cement. the sp was in aqueous solution state with solid mass content of 20% and (4) (5)( ) %1001 ×                 − − −+         − − = q s q l q s q p s p l p s p dd dd dd dd cpft ζζ          sl s dd dd lnln lnln  experimental verification 111 journal of sustainable architecture and civil engineering 2016/3/16 relative density of 1.03. in view of the large specific surface area of sfc, the saturation dosage of sp (which is a surface reactant) was more appropriately expressed in term of liquid mass per solid surface area of cementitious materials (kg/m2). from previous studies, the saturation dosage of sp was found to be 26×10-6 kg/ m2 (kwan et al. 2012), this dosage was adopted for fig. 1 particle size distributions of opc and sfc (6) all cementitious paste mixes. it should be noted that if the dosage is converted to mass of sp per mass of cementitious materials, it would increase with the sfc content due to the high fineness of sfc relative to opc. in the following, the particle size distributions and packing densities of blended cementitious paste mixes are studied. the mixes were assigned the labels pd-0, pd-10, pd-20 and pd-30 with the sfc content varied amongst 0%, 10%, 20% and 30% by mass of the total cementitious materials, respectively. to determine the particle size distribution of the cementitious paste, the sfc content by mass needs to be converted to sfc content by volume using the below equation:       sfc cmsfc opc cmsfc sfc cmsfc cm sfc mmmm mm v v      1 in equation (6), the subscript cm stands for cementitious materials (i.e. opc together with sfc in this context), (vsfc/vcm) is the sfc content by volume, (msfc/mcm) is the sfc content by mass, ρsfc is the solid density of sfc, and ρopc is the solid density of opc. with the sfc content by volume evaluated, the particle size distribution curves of pd-0, pd-10, pd-20 and pd-30 are determined as depicted in fig. 2. the value of ds in equations (4) and (5) is taken as the size where no more than 2.0% of the particles by volume were finer, and it is found to be 1.0 μm. the value of dl in equations (4) and (5) is taken as the size where no less than 98.0% of the particles by volume were coarser, and it is found to be 36.2 μm. by numerical optimization, setting q = –p = 0.16 for the modified distribution moduli could best resemble the geometrical shape of particle size distribution curves of the blended cementitious paste. correspondingly, the variation of cpft with particle size d is evaluated as plotted in fig. 2, and this represents the optimal particle size distribution. from fig. 2, it can be observed, that the particle size distribution of mix pd-0 (cement paste) does not resemble the curve of optimal particle size distribution. by blending with sfc, the particle size distributions of pd-10 and pd-20 are close to the optimal curve, this indicates the desirable effect of sfc in improving the particle size distribution. however, when the sfc content is further increased, the particle size distribution of pd-30 becomes dissimilar to the optimal curve. it is because the sfc content of 30% is excessive. for ease of visualizing the effect of values of p on the shape of particle size distribution curve, journal of sustainable architecture and civil engineering 2016/3/16 112 fig. 3 plots the variations of cpft with d calculated per equation (4) for p = 0.1, 0.2, 0.3 and 0.4. the value of q is fixed at 1.0 for comparison with the modified andreasen’s equation. in general, the smaller is the value of p, the higher is the curve of cpft. in other words, a smaller value of modified distribution modulus indicates higher content of finer particles and vice versa. in contrast, from previous studies on production of hpc (zheng and kwan 2006), it had been concluded that for hpc mixes with desirable flowability and strength performance, the values of distribution modulus m were within the range from 0.22 to 0.26 in the modified andreasen’s equation (funk and dinger 1994). the cpft calculated per equation (3) with the values of m varying from 0.1 to 0.4 are plotted in fig. 3. fig. 2 particle size distributions of cementitious paste the packing densities of cementitious paste mixes were measured using the wet packing test method. the procedures of wet packing test have been outlined in wong et al. (2007) and wong and kwan (2008a). the principle behind the wet packing test is briefly explained as follows. the solid concentration ϕ refers to the ratio of solid volume of cementitious materials vcm to the bulk volume of paste mix v, i.e.: fig. 3 particle size distribution curves per modified andreasen’s equation and proposed model ϕ = vcm/v (7) (8) the voids content ε is defined as the ratio of volume of voids to the bulk volume of paste mix, and the voids ratio u is defined as the ratio ε = (v – vcm)/v (9)ε ε − = 1 u of volume of voids to the solid volume of cementitious materials. therefore, the subjects of equations (7) to (9) are inter-related by the following equation: (10) u+ =−= 1 1 1 εφ 113 journal of sustainable architecture and civil engineering 2016/3/16 for a paste mix with a given proportioning of cementitious materials, ϕ and u are dependent on the w/cm ratio. generally, as the w/cm ratio increases from an inadequately low value, ϕ increases with water content until attaining the maximum, and then decreases with further increasing water content. the maximum solid concentration ϕmax corresponds to the minimum voids ratio umin. for ease of reference, the paste mixes for packing density measurement are assigned mix numbers in the form of pd-(sfc content). for each of the mixes pd-0, pd-10, pd-20 and pd-30 as given in table 1, multiple samples of cementitious materials in the same proportioning were each mixed with water at varying w/cm ratio and with the same dosage of sp. the bulk density of each sample was measured and the maximum solid concentration ϕmax amongst the samples was determined as the packing density. table 1 lists the packing density and voids ratio results. comparing the paste mixes with and without sfc, the positive effects of blending with sfc as demonstrated by the increase in packing density and reduction in voids ratio are apparent. however, when the sfc content increased from 20% to 30%, the packing density decreased slightly and the voids ratio increased slightly. using the mix pd-0 as the baseline of comparison, the maximum increase in packing density was 6.6% at sfc content of 20%, and the corresponding reduction in voids ratio was 17.0%. in the next step, the flow spread, flow rate, rheological properties and cube strength of cementitious paste mixes with various sfc contents and w/cm ratios were evaluated. this is for the purpose of verifying the positive effects of improved particle size distribution on the performance of cementitious paste. as shown earlier, the particle size distribution and packing density of cementitious paste blended with 30% sfc are not desirable. hence, such a high sfc content was not adopted. in the remaining investigations of flowability, rheology and strength, the sfc content by mass was varied among 0, 10% and 20%. the w/cm ratio by mass was varied from 0.18 to 0.30 in increments of 0.02. for ease of reference, each of the cementitious paste mixes is assigned a number in the form of cp-(sfc content)-(w/cm ratio). due to the high fineness of sfc, during mixing with water, the cementitious materials would tend to form water-bound granules with dry surfaces rather than coalesced to become a thick paste, even if the mixing time is reasonably prolonged. to facilitate thorough mixing of the ingredients, a special mixing sequence such that the cementitious materials and sp were divided into several portions, which were added one at a time to the water in the mixing bowl and mixed to form a slurry (wong and kwan 2008a), was required. the flow spread represents the static flowability of cementitious paste, and it was measured with the mini slump cone test. details of the mini slump cone have been described in okamura and ouchi (2003). the flow rate represents the dynamic flowability of cementitious paste, and it was measured with the marsh cone test as specified in european standard en 445: 2007. the rheological properties were obtained using a shear rate-controlled rheometer (fig. 4) which applied table 1 packing density and voids ratio of cementitious paste mixes mix no. sfc content (%) packing density change in packing density (%) voids ratio change in voids ratio (%) pd-0 0% 0.637 0.570 pd-10 10% 0.659 +3.4% 0.517 -9.3% pd-20 20% 0.679 +6.6% 0.473 -17.0% pd-30 30% 0.678 +6.4% 0.475 -16.7% journal of sustainable architecture and civil engineering 2016/3/16 114 torque through the spindle to shear the paste sample. the shearing sequence was applied in two cycles: the first shearing cycle (pre-shearing cycle) for ensuring each paste sample had undergone the same shearing history before measurement; and the second shearing cycle (data-logging cycle) for actual measurement and recording by a data-logger (wong and kwan 2008b). during each shearing cycle, the shear rate was increased from 0 to 50 s-1 in 75 sec, and then decreased to 0 s-1 in another 75 sec. two shear stress (τ) versus shear rate (γ) curves, one at increasing shear rate and the other at decreasing shear rate, could be obtained. the latter τ-γ curve, which was generally more consistent and repeatable, was used for evaluating the rheological properties of the paste sample. finally, the compressive strength was obtained from cube crushing test with 70.7 mm cubes based on averaged results of 3 cubes. fig. 4 rheometer employed in study the flow spread and flow rate results are summarized in table 2. the flow spread is plotted against the w/cm ratio in fig. 5, from which it can be seen that by blending with sfc in the paste mixes, the flow spread-w/cm curve was shifted upwards and to the left. in other words, the flow spread is increased at the same w/cm ratio, and for the same flow spread performance a lower w/cm can be adopted to achieve higher strength and denser microstructure. besides, it is observed that when the w/cm ratio is lower than 0.24, the flow spread-w/cm curve for 20% sfc content lies above the curve for 10% sfc, indicating better flowability of paste samples with 20% sfc. nevertheless, the two curves intersect at w/cm ratio of around 0.24 and at higher w/cm ratios, the flow spread of paste samples with 10% sfc was marginally larger than that of paste samples with 20% sfc. the results of flow rate demonstrate similar trend to the flow spread. with addition of sfc, a higher flow rate than cement paste without sfc could be obtained. moreover, blending with 20% sfc is more beneficial than blending with 10% sfc when the w/cm ratio is lower than 0.26. nevrheological and mechanical performance of paste fig. 5 flow spread versus w/ cm ratio ertheless, when the w/cm ratio is at 0.26 or higher, the flow rates of paste samples with sfc contents of 10% and 20% are similar. at w/ cm ratio equal to 0.30, the flow rate of paste sample with 10% sfc is higher than that of paste sample with 20% sfc. the flow rate is plotted against the flow spread in fig. 6. it is obvious that the flow spread and flow rate are highly correlated, regardless of the sfc content. therefore, it can be concluded that the static flowability and dynamic flowability of 115 journal of sustainable architecture and civil engineering 2016/3/16 table 2 experimental results of cementitious paste mixes mix no. flow spread (mm) flow rate (ml/s) yield stress (pa) apparent viscosity (pa·s) flow index 7-day cube strength (mpa) 28-day cube strength (mpa) ratio of 28day strength to 7-day strength cp-0-0.18 0.0 0.0 93.7 97.7 1.04 cp-0-0.20 0.0 0.0 95.4 105.7 1.11 cp-0-0.22 113.5 2.1 17.53 3.23 1.16 108.1 119.4 1.10 cp-0-0.24 167.0 7.4 6.66 1.98 1.23 105.5 119.1 1.13 cp-0-0.26 205.0 9.9 3.89 1.47 1.32 101.5 116.4 1.15 cp-0-0.28 233.3 13.2 2.01 1.05 1.34 94.7 104.7 1.11 cp-0-0.30 248.5 15.5 0.96 0.79 1.39 87.1 98.6 1.13 cp-10-0.18 0.0 0.0 108.5 113.7 1.05 cp-10-0.20 90.8 1.1 29.86 4.39 1.07 116.9 119.8 1.02 cp-10-0.22 148.3 4.1 10.62 2.73 1.12 115.4 124.8 1.08 cp-10-0.24 183.0 8.1 8.23 1.86 1.21 112.8 122.9 1.09 cp-10-0.26 217.0 10.8 3.12 1.41 1.29 104.6 117.1 1.12 cp-10-0.28 234.5 13.6 2.02 1.08 1.35 101.7 110.9 1.09 cp-10-0.30 252.0 17.0 1.05 0.71 1.41 94.5 102.3 1.08 cp-20-0.18 51.0 0.0 126.2 130.3 1.03 cp-20-0.20 112.8 2.0 33.43 5.03 1.01 136.7 137.7 1.01 cp-20-0.22 163.0 5.7 16.81 3.10 1.05 131.0 132.1 1.01 cp-20-0.24 186.8 9.3 12.73 2.06 1.16 123.1 129.5 1.05 cp-20-0.26 204.0 11.1 6.37 1.71 1.22 113.4 121.9 1.07 cp-20-0.28 233.8 13.8 2.97 1.46 1.31 105.7 116.4 1.10 cp-20-0.30 250.3 16.2 2.63 0.90 1.38 99.8 104.2 1.04 the cementitious paste correlate strongly with each other. from the rheometer testing, the shear stress-shear rate curve obtained may be described in terms of an appropriate rheological model, such as the commonly used bingham model (bingham 1916) and herschel-bulkley model (herschel and bulkley 1926). the bingham model is given by the following equation: fig. 6 flow rate versus flow spread (11)τ = τy + μγ (12)τ = τy + kγn where τ (pa) is the shear stress, τy (pa) is the yield stress, γ (s-1) is the shear rate, and μ (pa·s) is the plastic viscosity. the herschel-bulkley model is given by the following equation: where k (pa·sn) is the consistency index, n (dimensionless) is the flow index, and other symbols have the same meaning as defined in equation (11). it was found that the herjournal of sustainable architecture and civil engineering 2016/3/16 116 schel-bulkley model agreed better with the experimental results and it was therefore adopted in evaluating the rheological properties of cementitious paste mixes. for each paste sample, the best-fit curve that accorded with equation (12) was obtained by regression analysis. from the bestfit curve, τy is taken as the value of τ at γ = 0 s-1, and the apparent viscosity μa (pa·s) is taken as the ratio of τ/γ at γ = 50 s-1. the n-value of the best-fit curve represents the degree of shear thickening of the cementitious paste: if n < 1, it implies shear thinning, whereas if n > 1, it implies shear thickening. the values of τy, μa and n for the paste mixes are summarized in table 2. from the tabulated results, it can be seen that in general, τy and μa decreased with increasing w/cm, and n increased with increasing w/cm. the effects of 10% sfc content on τy and μa are not very pronounced, while at 20% sfc content, both τy and μa were increased. a higher sfc content caused n to decrease (i.e. the degree of shear thickening was reduced) when the w/ cm ratio was lower than 0.28, while the effect of sfc content on n was insignificant when the w/cm ratio was higher than 0.28. on the other hand, the rheological properties are more related to the flow rate (which represents the dynamic flowability) of paste mixes, as shown below. in fig. 7 to fig. 9, the τy, μa and n values are respectively plotted fig. 7 yield stress versus flow rate fig. 8 apparent viscosity versus flow rate fig. 9 flow index versus flow rate against the flow rate. it can be seen in fig. 7 that τy generally decreased with increasing flow rate. the yield stress-flow rate curves for paste with 0% and 10% sfc contents intersect at a number of points, while the curve for paste with 20% sfc content was shifted upwards, indicating a higher τy at the same level of flow rate. similar observations are noted in fig. 8, where μa generally decreased with increasing flow rate. the apparent viscosity-flow rate curves for paste with 0% and 10% 117 journal of sustainable architecture and civil engineering 2016/3/16 fig. 10 compressive strength versus w/cm fig. 11 compressive strength versus flow spread sfc contents overlap at a number of portions, while the curve for paste with 20% sfc content was shifted upwards, indicating a higher μa at the same flow rate. in fig. 9, it can be seen that the flow index-flow rate curves were shifted downwards as the sfc content increased from 0% through 10% to 20%, indicating a smaller degree of shear thickening at the same level of flow rate. the results of 7-day and 28-day cube compressive strength and the ratio of 28-day strength to 7-day strength are summarized in table 2. the maximum 28-day compressive strength achieved by cement paste without sfc was 119.4 mpa, while that achieved by paste with 10% and 20% sfc contents was respectively 124.8 mpa and 137.7 mpa. the 28-day strength is plotted against the w/cm and against the flow spread in fig. 10 and fig. 11, respectively. it is evident from fig. 10 that there existed a certain optimum w/cm ratio for maximum cube strength. when the w/cm ratio was lower than the optimum value, the strength increased with the w/cm ratio, whilst when the w/cm ratio was higher than the optimum value, the strength decreased with increasing w/cm ratio. moreover, it is observed that the optimum w/ cm ratio decreased at higher sfc content. therefore, blending with sfc would allow the adoption of a lower w/cm ratio to achieve higher strength. refer to fig. 11, the concurrent strength-flowability performance of cementitious paste is inspected. similar to the w/cm ratio, there is also certain optimum value of flow spread for maximum cube strength. as the sfc content increased from 0% through 10% to 20%, the strength-flowability performance curve was shifted upwards and to the right. this means by blending with sfc, both the strength and flowability of the cementitious paste can be increased simultaneously. the positive effects of sfc on concurrent strength-flowability performance would be attributed to the improvement of particle size distribution in the paste mix. the ratio of 28-day strength to 7-day strength is plotted against the flow spread in fig. 12. amongst all mixes, the ratio ranged from 1.02 to 1.15. in other words, at the age of 7 days, the paste mixes developed 87% to 99% of the 28-day strength. the curves in fig. 12 manifested a downward-shifting trend as the sfc content increased from 0% through 10% to 20%. this may be explained by the larger specific surface area of sfc to facilitate chemical reactions and enhance early-age strength development. journal of sustainable architecture and civil engineering 2016/3/16 118 the above experimental results demonstrated the beneficial effects of blending with sfc on the packing density, rheological and mechanical properties of cementitious paste. overall, in terms of packing density, flowability and strength, the paste samples blended with 20% sfc would outperform paste samples blended with 10% sfc, except the flow spread and flow rate of paste samples with 10% sfc at relatively high w/cm ratio were larger than or similar to fig. 12 ratio of 28-day strength to7-day strength versus flow spread those of paste samples with 20% sfc. in terms of yield stress and apparent viscosity, the paste samples blended with 10% sfc would be lower than those of paste samples with 20% sfc. the yield stress and viscosity should not be excessive and their desired ranges would be dependent on applications. for example, to achieve self-levelling property for high-flowability mortar, accessibility to far-reaching corners and passing ability through obstructions for self-consolidating concrete, and penetrability into gaps and fissures for cementitious grout, the yield stress and viscosity should be limited. the beneficial effects of blending with sfc would be due to the improvement in particle size distribution, which becomes closer to the proposed optimal curve. further experimental verifications with additional paste mixes containing various types of supplementary cementitious materials and fillers are necessary, in order to confirm the accuracy and universal applicability of the equation of optimal particle size distribution. moreover, further research is needed to generalise the proposed equation to aid the mix design of mortar and concrete. the existing mathematical models of ideal particle size distribution, which originated from aggregates for mortar and have been applied to mortar and concrete production, did not cater for the powder phase and hence is not directly applicable to cementitious paste mixes where the powder phase plays an important role while the aggregate phase is absent. modifications to the existing equations are necessary. a new equation of optimal particle size distribution has been developed in this paper. the proposed equation has been verified experimentally based on cementitious paste mixes produced by blending superfine cement (sfc) with ordinary portland cement (opc). the particle size distribution of cementitious paste blended with sfc was shown to be closer to the optimal particle size distribution. the wet packing density, flowability, rheology and strength performance of the cementitious paste mixes were measured. experimental results have demonstrated improvement in properties by blending with sfc, which rendered the particle size distribution in cementitious paste closer to the optimal. subject to further investigations to confirm its accuracy, the authors advocate utilization of the proposed equation of optimal particle size distribution for mix design optimization of cementitious paste, including cementitious grout and the paste phase in mortar and concrete. further research is needed to generalise the proposed equation to aid the mix design of mortar and concrete. conclusions the second author acknowledges the financial supported by the phd start-up fund of natural science foundation of guangdong province, china (project no. 2014a030310273).acknowledgment 119 journal of sustainable architecture and civil engineering 2016/3/16 anderegg f.o. grading aggregates ii: the application of mathematical formulas to mortars. industrial and engineering chemistry, 1931; 23(9): 1058-1064. https:/doi.org/10.1021/ie50261a018 andreasen a.h.m., andersen j. ueber die beziehung zwischen kornabstufung und zwischenraum in produkten aus losen körnern (mit einigen experimenten). kolloid-zeitschrift, 1930; 50(3): 217-228. https:/doi.org/10.1007/bf01422986 bingham e.c. an investigation of the laws of plastic flow. 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https:/doi.org/10.1061/(asce)0899-1561(2008) 20:2(189) wong h.h.c., ng i.y.t., ng p.l., kwan a.k.h. increasing packing density through ternary blending cement, fly ash and silica fume to improve cement paste rheology. in: malhotra v.m. fly ash, silica fume, slag, and natural pozzolans in concrete, aci special publication sp-242. michigan: american concrete institute; 2007: 433-446. zheng w., kwan a.k.h. optimising packing density for production of flowing high-performance concrete. in: proceedings, international conference on bridge engineering challenges in the 21st century, hong kong; 2006. references journal of sustainable architecture and civil engineering 2016/3/16 120 pui-lam ng researcher department of civil engineering, the university of hong kong adjunct professor faculty of civil engineering, vilnius gediminas technical university main research area sustainable concrete materials and structures, high-performance cementitious composites address sauletekio al. 11, vilnius lt10223, lithuania tel. +852-95875310 / +37062423921 e-mail: irdngpl@gmail.com jiajian chen lecturer department of civil engineering, foshan university main research area high-performance concrete and mortar, concrete technology address 18 jiangwan road, foshan, guangdong province, china tel. +86-13450891042 e-mail: chenjiajian@fosu.edu. cn albert kwok-hung kwan professor department of civil engineering, the university of hong kong main research area tall buildings, crack control of concrete structures, concrete materials and science address pokfulam, hong kong sar, china tel. +852-28592647 e-mail: khkwan@hku.hk about the authors journal of sustainable architecture and civil engineering 2015/2/11 72 jsace 2/11 journal of sustainable architecture and civil engineering vol. 2 / no. 11 / 2015 pp. 72-78 doi 10.5755/j01.sace.11.2.12568 © kaunas university of technology research of local compression concrete reinforced by steel fibres received 2015/03/02 accepted after revision 2015/06/01 research of local compression concrete reinforced by steel fibres valerijus keras, mindaugas augonis*, nerijus adamukaitis, eglė vaitekūnaitė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania the investigation was performed for estimation of influence of steel fibers to local compression of concrete. evaluation the fact that the reinforced concrete structures quite a lot could be loaded by local impact, the research of local zone strengthening with steel fibers were performed. it is known that the state of stress and strain in local zone of concrete loaded by concentrated forces is quite difficult. for that reason the experiments carried out to obtain the main parameters of local zone described by design standards and the results were compared with theoretical. there are investigated the stressstrain mode of fracture, increasing of local compression strength and the influence of fibers content. keywords: concrete, local compression, steel fibres, mode of fracture. *corresponding author: mindaugas.augonis@ktu.lt http://dx.doi.org/10.5755/j01.sace.11.2.12568 the investigation was provided for estimation of influence of steel fibers to local compression of concrete because such kind research is not quite popular. in practice there a lot situation when the reinforced concrete structures are loaded by local force, so, it’s important to investigate the strengthening possibilities of such sections. nowadays more popular became concrete reinforced by steel fibres. after concrete consist review, we can notice that several decades more and more fibres reinforcement is used for various building structures even for load bearing structures. assuming that steel fibres can to increase the resistance of local concrete area, it is possible to avoid the built-in parts in reinforced concrete structures. analyzing the behaviour of flexural reinforced concrete elements, we can notice that steel fibres are quite important factor not only for development of cracks but for increase of strength also (kaklauskas g., et. al., 2012, di prisco m., et.al. 2009, jones p. a. et. al., 2008, timinskas e., jakubovskis r., 2011). but that factor is not described in design standards. the ec2, str and snip standards are based on data of bach and bauschinger experiments. also, the classic flaman, mitchell, boussinesq and hertz solutions could be used. each method has some limitations and some advantages (venckevičius v., keras v., 1974). the standards are updating from time to time, but there is no presented algorithm of local compression strength calculation for concrete reinforced by steel fibres. as before, such algorithm could be prepared after performing a lot of experiments and summarizing of obtained results. the author’s takes it into account and performed some experiments with short term loading. in such investigations was used only one kind of concrete and steel fibre, but different content of fibres. introduction 73 journal of sustainable architecture and civil engineering 2015/2/11 for local compression testing were prepared 36 concrete specimens reinforced by diff erent content of fi bres. the dimension of specimens was 150x150x150. all specimens were hardened in the same conditions. as concrete aggregate were used the granite break stone by 5/20 fraction and sand by 0/4 fraction. the length of steel fi bre with hooked ends (fig.1) was 50 mm, diamemethods results and discussions fig. 1 the steel fibres with hooked ends were used for test materials in 1 m3 ratio of water/cement granite break stone, kg sand, kg cement (cem ii-42.5n), kg 1180 590 425 0.48 table 1 the composition of concrete the brittle failure character and let to develop quite high residual strain because of plasticity of steel and micro cracking in concrete (kaklauskas g., et. al., 2012). the fi bres quite eff ective operate to restrict the development of normal cracks so, it’s should be eff ective for inclined cracks in local zone also. concrete with high content of fibres concrete with low content of fibres concrete without fibres strain stress fig. 2. the stress-strain relationship of concrete reinforced by steel fibres. results and discussions the compression strength of concrete reinforced by steel fibres is presented in table 2. the scatter of concrete compression strength result is quite a small except the concrete with 35 kg content of fibres. the content of fibres can differently evaluate the compression strength of concrete. it depends on fibres type, bond with concrete, mortar fraction and so on (neves r. d. fernandes de almeida j.c.o, 2005). table 2. the compression strength of concrete reinforced by steel fibres content of fibres, kg/m3 strength, mpa 25 35.32 30 34.58 35 28.15 40 37.08 although the both area of loading was small, the tendency of results obtained different and it could be seen in figures 2, 3 and 4. in fig. 2 presented the results obtained when the plate 30x30 were used and in fig. 3 – when the 53x53 plate were used. in that figures the influence of fibres cannot be strictly estimated, and the arising of fibres content differently causes the local concrete strength. the distribution of local strength average values is presented in fig. 4 where could be noticed some tendency of fibres influence. when the specimens were loaded by 30x30 plate the maximum strength obtained with 25 kg/m3 fibres content and when by 53x53 plate – with 35 kg/m3. so, for specimens with small loaded area the influence of fibres is no significant and it hides in scatter of result data. for specimens with bigger load contact area, the influence becomes noticeable. reinforcing the concrete with fibres almost is no possibilities to control the direction and distribution. so, the possibility of stratification is real. in most cases the direction of fibres is not optimal to restrict the development of cracks at least for flexural and compressed members (kaklauskas g., et. al., 2012, di prisco m., et.al. 2009, jones p. a. et. al., 2008). according to this we can state that fibres with different properties (for ter – 1 mm and tensile strength 1150 mpa. the specimens were formed by 4 series with diff erent content of fi bres: in the fi rst series were mixed 0.32 % (25 kg/m3), in the second – 0.38 % (30 kg/m3), in the third – 0.44 % (35 kg/m3) and in the fourth – 0.50 % (40 kg/m3). each series includes 9 specimens. the composition of concrete presented in table 1. the specimens of each series were loaded by polished steel plates with two diff erent dimensions 53x53x23 and 30x30x20mm because it aff ect the load bearing of concrete (ince r., arici e., 2004, hawkins n., m., 1974). the plates were quite small for reason to evaluate the confi nement eff ect. the specimens were loaded uniformly until local zone failure. tests were performed by test hydraulic press machine with force velocity control. the use of fi bres should strengthen the local zone because according to the ordinary stress-strain diagram of concrete reinforced by steel fi bres, presented in fig. 2, can be seen that the steel fi bres decrease the compression strength of concrete reinforced by steel fi bres is presented in table 2. the scatter of concrete compression strength result is quite a small except the concrete with 35 kg content of fi bres. the content of fi bres can diff erently evaluate the compression strength of concrete. it depends on fi bres type, bond with concrete, mortar fraction and so on (neves r. d. fernandes de almeida j.c.o, 2005). fig. 2 the stress-strain relationship of concrete reinforced by steel fibres journal of sustainable architecture and civil engineering 2015/2/11 74 although the both area of loading was small, the tendency of results obtained different and it could be seen in figures 2, 3 and 4. in fig. 2 presented the results obtained when the plate 30x30 were used and in fig. 3 – when the 53x53 plate were used. in that figures the influence of fibres cannot be strictly estimated, and the arising of fibres content differently causes the local concrete strength. the distribution of local strength average values is presented in fig. 4 where could be noticed some tendency of fibres influence. when the specimens were loaded by 30x30 plate the maximum strength obtained with 25 kg/m3 fibres content and when by 53x53 plate – with 35 kg/m3. so, for specimens with small loaded area the influence of fibres is no significant and it hides in scatter of result data. for specimens with bigger load contact area, the influence becomes noticeable. reinforcing the concrete with fibres almost is no possibilities to control the direction and distribution. so, the possibility of stratification is real. in most cases the direction of fibres is not optimal to restrict the development of cracks at least for flexural and compressed members (kaklauskas g., et. al., 2012, di prisco m., et.al. 2009, jones p. a. et. al., 2008). according to this we can state that fibres with different properties (for example with less length) can be more effective to resist the local stress. it maybe could be more effective for concrete under cyclic load (breitenbucher r., 2007) table 2 the compression strength of concrete reinforced by steel fibres content of fibres, kg/m3 strength, mpa 25 35.32 30 34.58 35 28.15 40 37.08example with less length) can be more effective to resist the local stress. it maybe could be more effective for concrete under cyclic load (breitenbucher r., 2007) fig. 2. the distribution of the local compression strength fig. 3. the distribution of the local compression for specimens loaded by 30x30 plate. strength for specimens loaded by 53x53 plate. fig. 4. the distribution of the average local compression strength values according to different loaded area. in spite of loaded area and content of fibres the failure character was similar to concrete without any fibres. the initial micro cracks appear near corners of steel plate. at that time the steel plate are slumped in concrete. such stamp in concrete remains and the initial cracks become wider and develop until specimen failures. the failure state is presented in fig. 5,6. the load when the first crack appears was not estimated. the failure of the plain concrete is brittle (keras v., 1972) and happens suddenly. the fibres change the failure to plastic (fig.2) and failure process becomes longer what is positive to position of structural design. example with less length) can be more effective to resist the local stress. it maybe could be more effective for concrete under cyclic load (breitenbucher r., 2007) fig. 2. the distribution of the local compression strength fig. 3. the distribution of the local compression for specimens loaded by 30x30 plate. strength for specimens loaded by 53x53 plate. fig. 4. the distribution of the average local compression strength values according to different loaded area. in spite of loaded area and content of fibres the failure character was similar to concrete without any fibres. the initial micro cracks appear near corners of steel plate. at that time the steel plate are slumped in concrete. such stamp in concrete remains and the initial cracks become wider and develop until specimen failures. the failure state is presented in fig. 5,6. the load when the first crack appears was not estimated. the failure of the plain concrete is brittle (keras v., 1972) and happens suddenly. the fibres change the failure to plastic (fig.2) and failure process becomes longer what is positive to position of structural design. example with less length) can be more effective to resist the local stress. it maybe could be more effective for concrete under cyclic load (breitenbucher r., 2007) fig. 2. the distribution of the local compression strength fig. 3. the distribution of the local compression for specimens loaded by 30x30 plate. strength for specimens loaded by 53x53 plate. fig. 4. the distribution of the average local compression strength values according to different loaded area. in spite of loaded area and content of fibres the failure character was similar to concrete without any fibres. the initial micro cracks appear near corners of steel plate. at that time the steel plate are slumped in concrete. such stamp in concrete remains and the initial cracks become wider and develop until specimen failures. the failure state is presented in fig. 5,6. the load when the first crack appears was not estimated. the failure of the plain concrete is brittle (keras v., 1972) and happens suddenly. the fibres change the failure to plastic (fig.2) and failure process becomes longer what is positive to position of structural design. fig. 2 the distribution of the local compression strength for specimens loaded by 30x30 plate fig. 3 the distribution of the local compression strength for specimens loaded by 53x53 plate fig. 4 the distribution of the average local compression strength values according to different loaded area 75 journal of sustainable architecture and civil engineering 2015/2/11 in spite of loaded area and content of fi bres the failure character was similar to concrete without any fi bres. the initial micro cracks appear near corners of steel plate. at that time the steel plate are slumped in concrete. such stamp in concrete remains and the initial cracks become wider and develop until specimen failures. the failure state is presented in fig. 5, 6. the load when the fi rst crack appears was not estimated. the failure of the plain concrete is brittle (keras v., 1972) and happens suddenly. the fi bres change the failure to plastic (fig.2) and failure process becomes longer what is positive to position of structural design. fig. 5 the failure view of specimen with 30x30 load area fig. 6 the failure view of specimen with 53x53 load area when the loading areas are small, the initial cracks are brighter and wider, but when the areas are bigger there are more cracks which develop in various directions. some cracks are very narrow and remain such until fully failure. but failure character is similar for both series specimens. the reviewed character of failure can be distinguished in several stages (fig. 7, 8). in the fi rst stage (1-2) can be seen the process of compaction and the modulus of deformation uniformly increase (fig.8). in the second stage (2-3) the modulus of deformation remains constant and only the elastic strain develops in specimen. in the third stage (4-5) the micro cracks begin appears and the deformation modulus begins decrease. such micro cracks begin to connect into the macro cracks and the maximum stress is reached. of course the distribution of cracks should be a little bit different because of diff erent boundary zones. when the plate 30x30 was used the eff ective area at the specimen bottom not exceeds the specimen area, but if the 53x53 mm plate were used the eff ective area exceeds the area of specimen bottom. journal of sustainable architecture and civil engineering 2015/2/11 76 fig. 8 the stress-strain relationship of specimen with 53x53 load area fig. 7 the stress-strain relationship of specimen with 30x30 load area aft er comparing such two diff erent cases we can conclude that the scatter of results could not so diff erently aff ect the relation curves. to substantiate it the mean square deviation (msd) and coeffi cient of variation (vc) was calculated (table 3). the variation of results is not high if to compare with fl exural members. it’s interesting to compare experimental results with theoretical, calculated according to ec2, str and snip codes. the load area is not signifi cant to the local concrete strength at all. the local strength with 30x30 area plates is 141.3, 60.0 and 62.6 mpa according to ec2, str and snip. with 53x53 plate the local strength is 80.0, 60.0 and 60.2 mpa respectively. in calculations were assumed the cylindrical strength of concrete. also, calculating the local strength by ec2 was assumed that eff ective area is limited by edges of specimens. according to str such area should not exceed 90x90 if the loaded area is 30x30. so, theoretically according to str and snip codes the diff erence of such two series specimens is not signifi cant, but according to ec2 diff erence is ~40%. such diff erence exceeds the variation of results and the fi bres could aff ect that. comparing theoretical results with experimental, the ec2 gives best coincidence for both cases. the various factors infl uent the strength of concrete under concentrated loads are investigated in other articles (venckevičius v., lukoševičius k., 2007, venckevičius v., 2005) table 3 the statistical parameters of specimens content of fi bres, kg/m3 compression with plate 30x30 compression with plate 53x53 msd vc, % msd vc, % 25 16.49 9.6 12.42 15.18 30 16.10 11.28 2.18 2.48 35 11.73 7.42 2.93 3.05 40 16.29 10.15 3.76 4.05 77 journal of sustainable architecture and civil engineering 2015/2/11 the failure character is similar in spite of partially loaded area 30x30 or 53x53 and the failure character is like for concrete without fibres. solving by influence of content of fibres to local strength we can summarize that arising of fibres content does not have influence for specimens loaded by 30x30 steel plates, but for specimens with 53x53 plates the influence is significant and effective until 35kg/m3 then begin to decrease. in such case the resistance to local stress increase until 15% comparing with plain concrete. the fibres effect depend on specimens dimensions, content and fibres properties and the rationally area of concentrated load. it, can be seen when the local strength values obtained by different codes is compared, because not all parameters are evaluated when the fibre concrete specimens is use. the best coincidence was obtained by ec2 code although not evaluating the fibres influence. conclusions str 2.05.05:2005. betoninių ir gelžbetoninių konstrukcijų projektavimas [design of concrete and reinforced concrete structures]. lst en 1992-1-1 gelžbetoninių konstrukcijų projektavimas. 1-1 dalis [eurocode 2: design of concrete structures. part 1-1] breitenbucher r. ibuk h., alowieh h. influence of cyclic loading on the degradation of mechanical concrete properties. in conference edition advance in construction materials 2007. heidelberg, berlin. part v: 317-324. hawkins n. m. the bearing strength of concrete loaded through rigid plates. journal of the structural division, 1974; 10(8): 1685-1702. keras v. apie betono sąlyginai trapias savybes. deformacijų koncentracija mikro objektuose, detalėse, konstrukcijose [about relatively brittle characteristics of concrete. the concentration of strain in micro-objects, components, constructions]. konferencijų medžiaga, kaunas, 1972: 114-118. neves r. d. fernandes de almeida j.c.o. compressive behaviour of steel fibre reinforced concrete, structural concrete, journal of the fib 2005, vol.6 no.1 ince r., arici e. size effect in bearing strength of concrete cubes. construction and building materials, 2004; vol. 18: 603–609. http://dx.doi. org/10.1016/j.conbuildmat.2004.04.002 venckevičius v., keras v. apie betoninių elementų stiprumo apskaičiavimo metodikų patikimumą (histogramų) vietinio gniuždymo atveju. deformacijų koncentracija mikro objektuose, detalėse, konstrukcijose [about reliability of calculation procedures of strength of concrete elements (histograms) of local compression case. the concentration of strain in micro-objects, components, referencesconstructions]. konferencijų medžiaga, kaunas, 1974: 51-58. venckevičius v., lukoševičius k. apie betoninių elementų skaičiavimą esant kraštiniam ir kampiniam vietiniam gniuždymui [about the calculation of concrete elements subjected to edge and corner local compression]. pažangioji statyba. konferencijų medžiaga, kaunas, 2007: 53-60. kaklauskas g., bačinskas d., gribniak v. kompozitais armuotos betoninės konstrukcijos [composite reinforced concrete structures]. vilnius, technika, 2012; 301. di prisco m., plizzari g., vandewalle l. fibre reinforced concrete: new design perspectives. materials and structures, 2009; 42(9): 1261-1281. http:// dx.doi.org/10.1617/s11527-009-9529-4 jones p. a., austin s. a., robins p. j. predicting the flexural load–deflection response of steel fibre reinforced concrete from strain, crack-width, fibre pull-out and distribution data. materials and structures, 2008; 41(3): 449-463. http://dx.doi. org/10.1617/s11527-007-9327-9 timinskas e., jakubovskis r. stiklo pluošto armatūra armuotų betoninių elementų eksperimentinis ir skaitinis tyrimas [experimental and analytical research of concrete beams reinforced with glass fiber reinforcement bars]. konferencijų medžiaga, vilnius, 2011: 1-5. venckevičius v. about the calculation of concrete elements subjected to local compression. journal of civil engineering and management, 2005; 11(3): 243-248. http://dx.doi.org/10.1080/13923730.200 5.9636355 снип 2.03. 01-84 бетонные и железобетонные конструкции [concrete and reinforced concrete structures]. москва 1989 journal of sustainable architecture and civil engineering 2015/2/11 78 valerijus keras assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area fracrure mechanics, concentration of stresses and strains, durability, destruction address studentų st. 48, lt51367 kaunas, lithuania about the authors mindaugas augonis assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area durability of engineering structures, strength and stability of reinforced concrete structures address studentų st. 48, lt51367 kaunas, lithuania, e-mail: mindaugas.augonis@ ktu.lt nerijus adamukaitis dr. lecturer kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area durability of engineering structures, strength and stability of steel structures address studentų st. 48, lt51367 kaunas, lithuania, e-mail: nerijus.adamukaitis@ ktu.lt eglė vaitekūnaitė student kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area engineering structures, partially loaded reinforced concrete members address studentų st. 48, lt51367 kaunas, lithuania 5 journal of sustainable architecture and civil engineering 2016/1/14 *corresponding author: evaldas.serelis@ktu.lt mechanical properties and microstructural investigation of ultra-high performance glass powder concrete received 2016/03/04 accepted after revision 2016/04/15 journal of sustainable architecture and civil engineering vol. 1 / no. 14 / 2016 pp. 5-11 doi 10.5755/j01.sace.14.1.14478 © kaunas university of technology mechanical properties and microstructural investigation of ultrahigh performance glass powder concrete jsace 1/14 http://dx.doi.org/10.5755/j01.sace.14.1.14478 introduction evaldas šerelis*, vitoldas vaitkevičius, vidas kerševičius kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania additive of glass powder was successfully utilized in ultra-high performance concrete (uhpc) mixture. during experiment was found, that glass powder can be used instead of silica fume (sf), without decrease of mechanical properties and microstructure can be significantly increased. in experiment 100 % of quartz powder was substituted by glass powder. quantitative and qualitative xrd analysis revealed, that glass powder improves hydration of portland cement and in such way additional compressive strength up to 40 mpa can be gained. designed mixtures were blended with laboratory mixer eirich r02t and later with industrial mixer hpgm 1125. in new uhpc mixture was incorporated different amount of steel fibres. flexural strength was increased about 5 times from 6.7 mpa to 36.2 mpa. keywords: uhpc, glass powder, xrd analysis. advances in concrete technology have led to develop a new type of cementitious composites: self-compacting concrete, self-healing concrete, 3d printing concrete, ultra-high performance concrete and etc. (nguyen et al, 2014). in this article we going to focus on ultra-higher performance concrete. uhpc with the very low water-to-cement ratio (w/c) demonstrates excellent workability, advanced mechanical and durability properties (yu et al 2014). these and other properties mainly depends on particle size distribution, packing density, optimal w/c ratio. so deeper literature review is needed to properly understand the material. tavakoli and heidari (2013) conducted microstructural investigations with scanning electron microscope (sem) micrographs and pinpointed, that uhpc differs a lot from the conventional concrete. author thinks, that concrete mixture with silica fume and low water to binder ratio leads to a very dense and homogenous structure. thus porosity and permeability to fluids can be decreased. author also denotes that composition with silica fume decreases amount and size of potlandite (ch) crystals. mainly due to positive effect of pozzolanic reaction. due to pozzolanic reaction ch crystals are consumed and addition calcium silicate hydrates (csh) are formed. thus compressive strength increased further and other mechanical properties can be improved. alawode et al (2011) during experiment, noticed that concrete with high w/c ratio tends to create large ch crystals, those large crystals serve as weak transition link between coarse aggregates, and thus during compressive strength tends to decrease. journal of sustainable architecture and civil engineering 2016/1/14 6 saccani and bignozzi (2010) noticed that silica fume not the only one pozzolanic material which has positive effect on cementitious material structure. authors confirmed, that glass powder also has positive effect. during the experiment they noticed, that alkali silica reaction can appear when particle size ranges from 0.075 mm to 2.00 mm. however if glass powder is milled to powder, pozzolanic reaction instead of alkali silica reaction can occur. du and tan (2013) also noticed positive effect of glass powder on cement hydration, however founded that powder of clear glass makes about 9 time higher expansion comparing to brown glass. increased expansion was explained due to reduced amount of cr2o3. wang and huang (2010) during experiment founded that lcd glass can increase compressive strength almost about 2 times from 40 mpa to 75 mpa. lin et al. (2008) made also similar experiments. author used 29si mas nmr methods and noticed that glass powder in cement system can drastically increase amount of csh. kou and xing (2012) in his research founded that glass powder has positive effect on cement hydration, however glass powder decreases early strength of concrete. author also denotes that reactivity of glass powder comparing to silica fume is very slow. karakurt and topçu (2011) suggested that combination with ground granulated blast-furnace slag, natural zeolite and fly ashes has positive effect when ternary system with alkalis activated. created binder is highly resistant to sulphate environment. shafaatian et al. (2013) during experiment used crushed glass with particle size from 150 µm to 4.75 mm and noticed that asr gel occurs only in cracks between large particles of crushed glass. schwarz and neithalath (2008) created a model in which described when glass powder tends to create alkali silica reaction and when acts as pozzolanic material. the main aim of this article using qualitative and quantitative xrd analysis, mercury porosimetry and other test methods to find out how combination of glass powder and micro steel fibers affects the compressive strength of uhpc. cement. the main properties of cem i 52.5 r cement: the paste of normal consistency – 28.5%; specific surface (by blaine) – 4840 cm2/kg; the setting time (initial/final) is 110/210 min; the compressive strength (after 2/28 days) – 32.3/63.1 mpa; the soundness (by le chatelier) – 1.0 mm. the mineral composition: c3s – 68.70; c2s – 8.70; c3a – 0.20; c4af – 15.90. the particle size distribution is shown in fig. 1. silica fume (sf). main properties of silica fume: bulk density – 400 kg/m3; density – 2532 kg/m3; ph – 5.3. the particle size distribution is also shown in fig. 1. used materials fig. 1 particle size distribution of silica fume, portland cement, quartz powder, 0/0.5 fr. quartz sand and uhpc mixture to sulphate environment. shafaatian et al. (2013) during experiment used crushed glass with particle size from 150 µm to 4.75 mm and noticed that asr gel occurs only in cracks between large particles of crushed glass. schwarz and neithalath (2008) created a model in which described when glass powder tends to create alkali silica reaction and when acts as pozzolanic material. the main aim of this article using qualitative and quantitative xrd analysis, mercury porosimetry and other test methods to find out how combination of glass powder and micro steel fibers affects the compressive strength of uhpc. 2. used materials cement. the main properties of cem i 52.5 r cement: the paste of normal consistency 28.5%; specific surface (by blaine) 4840 cm2/kg; the setting time (initial/final) is 110/210 min; the compressive strength (after 2/28 days) 32.3/63.1 mpa; the soundness (by le chatelier) 1.0 mm. the mineral composition: c3s – 68.70; c2s – 8.70; c3a – 0.20; c4af – 15.90. the particle size distribution is shown in fig. 1. silica fume (sf). main properties of silica fume: bulk density – 400 kg/m3; density – 2532 kg/m3; ph – 5.3. the particle size distribution is also shown in fig. 1. fig. 1. particle size distribution of silica fume, portland cement, quartz powder, 0/0.5 fr. quartz sand and uhpc mixture quartz powder (qp). the main properties of quartz powder: the bulk density is 900 kg/m3; the density 2671 kg/m3; the specific surface (by blaine) 3450 cm2/g; the average particle size 18.12 µm. the particle size distribution is shown in fig. 1. glass powder (gp). the main properties of glass powder: specific surface (by blaine) 3350 cm2/g; density 2528 kg/m3; the average particle size 25.80 µm. quartz sand (qs). the main properties of quartz sand: fraction 0/0.5; specific surface (by blaine) numerical value is 91 cm2/g; density 2650 kg/m3. chemical admixture. superplasticizer (sp) based on polycarboxylic ether (pce) polymers with the following main properties: appearance dark brown liquid; specific gravity (20 ºc) 1.08 ± 0.02 g/cm3; ph value 7.0 ± 1; the viscosity 128 ± 30 pa·s; has 65.0% alkali content and 60.1% chloride content. micro steel fibres. the main properties of the fibres: the length 13 mm, the diameter 0.30 mm and the tensile strength 1000 mpa. 0 20 40 60 80 100 0 2 4 6 8 10 0 1 10 100 1000 10000 c um ul at iv e, % pa rt ic le v ol um e, % particle size, µm cem i 52.5 r silica fume quartz powder quartz sand 0/0.5 fr. uhpc mixture 7 journal of sustainable architecture and civil engineering 2016/1/14 quartz powder (qp). the main properties of quartz powder: the bulk density is 900 kg/m3; the density 2671 kg/m3; the specific surface (by blaine) 3450 cm2/g; the average particle size – 18.12 µm. the particle size distribution is shown in fig. 1. glass powder (gp). the main properties of glass powder: specific surface (by blaine) – 3350 cm2/g; density 2528 kg/m3; the average particle size 25.80 µm. quartz sand (qs). the main properties of quartz sand: fraction 0/0.5; specific surface (by blaine) numerical value is 91 cm2/g; density – 2650 kg/m3. chemical admixture. superplasticizer (sp) based on polycarboxylic ether (pce) polymers with the following main properties: appearance – dark brown liquid; specific gravity (20 ºc) – 1.08 ± 0.02 g/cm3; ph value – 7.0 ± 1; the viscosity – 128 ± 30 pa·s; has 65.0% alkali content and 60.1% chloride content. micro steel fibres. the main properties of the fibres: the length 13 mm, the diameter – 0.30 mm and the tensile strength 1000 mpa. glass powder preparation. in experiment recycled glass crushed from various bottle were used. crushing was made in two steps: in first step bottles were crushed with jaw crusher to an average particle size of 0.3-0.8 cm, and later with vibratory disc mill coarse aggregates of glass were milled to powder. the rotation speed of vibratory disc mill was 750–940 rpm. specific surface and particle size distribution. the specific surface was measured according to en 196-6:2010 standard and particle size distribution was measured with mastersize 2000 instrument produced by malvern instruments ltd. mixing, sample preparation and curing. fresh concrete mixes were prepared with eirich r02 mixer. the mixtures were prepared from dry aggregates. the cement and aggregates were dosed by weight while water and chemical admixtures were added by volume. cylinders (d = 50 mm, h = 50 mm) were formed for the research in order to determine the properties of concrete. homogeneous mixes were cast in moulds and stored for 24 h at 20 ºc/95 rh (without compaction). after 24 h, thermal treatment (1 + 18 + 3) was applied and during the remaining time till the end of the 28 day-day period, the specimens were stored under water at 20 ºc. methods table 1 mixing procedure of ultra-high performance concrete time, sec. mixing procedure 60 homogenization of binder and inter materials (silica fume, cement, quartz powder and quartz sand) 30 addition 100% of water and 50% superplasticizer 60 homogenization 120 pause 30 addition of the remaining superplasticizer 120 addition of steel fibres and homogenization flexural and compressive strength. the flexural and compressive strength test was performed according to en 12390-5 and en 12390-4 standards. for flexural 3 specimens (40x40x160 mm) were created, for compressive strength 6 cylinders (d = 50 mm; h = 50 mm) were created. x-ray diffraction (xrd) analysis. hardened cement pastes were used for xrd analysis. the xrd measurements were performed with xrd 3003 tt diffractometer manufactured by ge sensing & inspection technologies gmbh with θ-θ configuration und cuka radiation (λ = 1.54 å). the angular range was from 5º to 70º 2 theta with a step width of 0.02º and a measuring time of 6 s/step. for journal of sustainable architecture and civil engineering 2016/1/14 8 xrd quantitative phase analysis when using the rietveld refinement, the samples were mixed with 20 wt. % zno (a standard material widely used in xrd analysis) as an internal standard and stored in argon atmosphere until measurement. this allows us to derive the estimation of the amount of non-crystalline phases on the grounds of the rietveld fitting procedure. constituents composition qp/gp0 qp/gp100 qp/gp100sf/gp100 sf/gp100 water, l 186 cement, kg/m3 735 w/c 0.25 silica fume, kg/m3 99 quarz powder, kg/m3 412 412 glass powder, kg/m3 391 489 99 quarz sand 0/0.5, kg/ m3 962 superplasticizer, l 30.65 table 2 compositions of ultrahigh performance concrete during experiment four compositions of ultra-high performance concrete were created. compositions were modified substituting quartz powder to glass powder (table 2). reverence composition, which had no glass powder was denoted as qp/gp0. composition where 100 % of glass powder was substituted to glass powder was denoted as qp/gp100. composition where silica fume and quarts powder were substituted to glass powder was denoted to qp/gp100sf/gp100 and composition where silica fume was substituted to glass powder was denoted to sf/gp100. xrd analysis fig. 2 illustrates the xrd patterns of the four hardened cement. ch phase was found at d equalling 0.3042; 0.2789 and 0.1924 nm. higher reduction of ch phase was observed in compositions with higher amount of glass powder. glass powder also had positive effect on reduction of intensities of c2s and c3s phases. c2s was found at the following levels of d: 0.2790; 0.2783; 0.2745; results and discussion fig. 2 xrd patterns of hardened cement pastes with different amounts of glass powder 4. results and discussion during experiment four compositions of ultra-high performance concrete were created. compositions were modified substituting quartz powder to glass powder (table 2). reverence composition, which had no glass powder was denoted as qp/gp0. composition where 100 % of glass powder was substituted to glass powder was denoted as qp/gp100. composition where silica fume and quarts powder were substituted to glass powder was denoted to qp/gp100sf/gp100 and composition where silica fume was substituted to glass powder was denoted to sf/gp100. 4.1. xrd analysis fig. 2 illustrates the xrd patterns of the four hardened cement. ch phase was found at d equalling 0.3042; 0.2789 and 0.1924 nm. higher reduction of ch phase was observed in compositions with higher amount of glass powder. glass powder also had positive effect on reduction of intensities of c2s and c3s phases. c2s was found at the following levels of d: 0.2790; 0.2783; 0.2745; 0.2645; 0.2610; 0.2189 nm while c3s phases were found at d equalling 0.3036; 0.2773; 0.2748; 0.2604; 0.2181 nm. experiment cleared out, that glass powders tends to increase hydration of portland cement. fig. 2. xrd patterns of hardened cement pastes with different amounts of glass powder rietvield refinement was additionally applied (table 2 and fig. 3). during experiment was noticed, that composition with glass powder reacted more intensively comparing with composition which had no glass powder. however with combination of silica fume and glass powder reaction increased even further. decreased amounts of c2s, c3s, ch phases denotes, that glass powder increased hydration process of cement, and also acted as pozzolanic material. so additional amount of csh phases is formed. this has positive effect on mechanical properties of uhpc. e f e p c c c cs z cs f a p z z cs cs f cs p z cs pcs p z cs cs z z z z 5 10 15 20 25 30 35 40 45 50 55 60 65 70 in te ns ity 2θ cu kα z zno (internal standard) e ettringite p portlandite c calcite cs c3s and c2s a c3a f c4af qp/gp100sf/gp100 sf/gp100 qp/gp100 qp/gp0 9 journal of sustainable architecture and civil engineering 2016/1/14 fig. 3 mineralogical composition of the binder with different amounts of glass powder fig. 4 compressive strength of uhpc with different amounts of glass powder 0.2645; 0.2610; 0.2189 nm while c3s phases were found at d equalling 0.3036; 0.2773; 0.2748; 0.2604; 0.2181 nm. experiment cleared out, that glass powders tends to increase hydration of portland cement. rietvield refinement was additionally applied (table 2 and fig. 3). during experiment was noticed, that composition with glass powder reacted more intensively comparing with composition which had no glass powder. however with combination of silica fume and glass powder reaction increased even further. decreased amounts of c2s, c3s, ch phases denotes, that glass powder increased hydration process of cement, and also acted as pozzolanic material. so additional amount of csh phases is formed. this has positive effect on mechanical properties of uhpc. xrd qualitative and quantitative analysis revealed, that glass powder has positive effect on cement hydration. further research showed, that compressive strength can be increased up to 40 mpa from 182 mpa to 221 mpa (fig. 4) when silica fume and quartz powder were substituted fig. 3. mineralogical composition of the binder with different amounts of glass powder fig. 4. compressive strength of uhpc with different amounts of glass powder xrd qualitative and quantitative analysis revealed, that glass powder has positive effect on cement hydration. further research showed, that compressive strength can be increased up to 40 mpa from 182 mpa to 221 mpa (fig. 4) when silica fume and quartz powder were substituted to glass powder. thus expensive silica fume can be eliminated. during the experiment was noticed, has silica fume is more reactive pozzolanic material compering with glass powder, however with glass powder better economic and ecological effect can be achieved. 4.3. mechanical properties after mix with industrial mixer during the research, it was unexpectedly observed that whenever glass powder was incorporated in uhpc composition, with the substitution up to 100% of quartz powder the compressive strength increased about 40 mpa from 182 mpa (fig.4) (gp/gp0) to 221 mpa (gp/gp100). such enormous compressive strength could be obtained in each plant manufacturing concrete as long as it is equipped with advanced and sophisticated technology; however most producers unfortunately cannot afford such equipment. in order to prepare uhpc with standard mixers, the concrete particle size distribution was modified according to yu et al. (2010) recommendations and the water-to-cement ratio was increased up to 0.30. fig. 5. the compressive and flexural strength of uhpc with various amounts of micro steel fibres (w/c=0.30) 0 20 40 60 80 100 a m ou nt , % qp/gp0 qp/gp100 qp/gp10sf/gp100 sf/gp100 182 221 185 153 0 50 100 150 200 250 c om pr es si ve s tr en gh t, m pa qp/gp0 qp/gp100 qp/gp100sf/gp100 sf/gp100 116 139 143 149 6.7 13.2 23.5 36.2 0 5 10 15 20 25 30 35 40 0 20 40 60 80 100 120 140 160 180 200 0.0 73.5 110.3 147.0 fl ex ur al s tr en gh t, m pa c om pr es si ve s tr en gh t, m pa amount of micro steel fibres, kg/m3 fig. 3. mineralogical composition of the binder with different amounts of glass powder fig. 4. compressive strength of uhpc with different amounts of glass powder xrd qualitative and quantitative analysis revealed, that glass powder has positive effect on cement hydration. further research showed, that compressive strength can be increased up to 40 mpa from 182 mpa to 221 mpa (fig. 4) when silica fume and quartz powder were substituted to glass powder. thus expensive silica fume can be eliminated. during the experiment was noticed, has silica fume is more reactive pozzolanic material compering with glass powder, however with glass powder better economic and ecological effect can be achieved. 4.3. mechanical properties after mix with industrial mixer during the research, it was unexpectedly observed that whenever glass powder was incorporated in uhpc composition, with the substitution up to 100% of quartz powder the compressive strength increased about 40 mpa from 182 mpa (fig.4) (gp/gp0) to 221 mpa (gp/gp100). such enormous compressive strength could be obtained in each plant manufacturing concrete as long as it is equipped with advanced and sophisticated technology; however most producers unfortunately cannot afford such equipment. in order to prepare uhpc with standard mixers, the concrete particle size distribution was modified according to yu et al. (2010) recommendations and the water-to-cement ratio was increased up to 0.30. fig. 5. the compressive and flexural strength of uhpc with various amounts of micro steel fibres (w/c=0.30) 0 20 40 60 80 100 a m ou nt , % qp/gp0 qp/gp100 qp/gp10sf/gp100 sf/gp100 182 221 185 153 0 50 100 150 200 250 c om pr es si ve s tr en gh t, m pa qp/gp0 qp/gp100 qp/gp100sf/gp100 sf/gp100 116 139 143 149 6.7 13.2 23.5 36.2 0 5 10 15 20 25 30 35 40 0 20 40 60 80 100 120 140 160 180 200 0.0 73.5 110.3 147.0 fl ex ur al s tr en gh t, m pa c om pr es si ve s tr en gh t, m pa amount of micro steel fibres, kg/m3 to glass powder. thus expensive silica fume can be eliminated. during the experiment was noticed, has silica fume is more reactive pozzolanic material compering with glass powder, however with glass powder better economic and ecological effect can be achieved. mechanical properties after mix with industrial mixer during the research, it was unexpectedly observed that whenever glass powder was incorporated in uhpc composition, with the substitution up to 100% of quartz powder the compressive strength increased about 40 mpa from 182 mpa (fig.4) (gp/ gp0) to 221 mpa (gp/gp100). such enormous compressive strength could be obtained in each plant manufacturing concrete as long as it is equipped with advanced and sophisticated technology; however most producers unfortunately cannot afford such equipment. in order to prepare uhpc with standard mixers, the concrete particle size distribution was modified according to yu et al. (2010) recommendations and the water-to-cement ratio was increased up to 0.30. journal of sustainable architecture and civil engineering 2016/1/14 10 interesting fact was observed, when composition was mixed with industrial mixer (fig. 5). during experiment we added up to 147 kg/m3 of micro steel fibres, the compressive strength increased about 30% from 116 mpa (qp/gp0-f0) to 149 mpa (qp/gp0-f147) whereas the flexural strength increased more than 5 times from 6.7 mpa (qp/gp0-f0) to 36.2 mpa (qp/gp0-f147). the experiment results proved that micro steel fibres exert a positive effect on the compressive and flexural strength of uhpc. created compositions could be used for various elements made of concrete with excellent durability and mechanical properties. fig. 5 the compressive and flexural strength of uhpc with various amounts of micro steel fibres (w/ c=0.30) fig. 3. mineralogical composition of the binder with different amounts of glass powder fig. 4. compressive strength of uhpc with different amounts of glass powder xrd qualitative and quantitative analysis revealed, that glass powder has positive effect on cement hydration. further research showed, that compressive strength can be increased up to 40 mpa from 182 mpa to 221 mpa (fig. 4) when silica fume and quartz powder were substituted to glass powder. thus expensive silica fume can be eliminated. during the experiment was noticed, has silica fume is more reactive pozzolanic material compering with glass powder, however with glass powder better economic and ecological effect can be achieved. 4.3. mechanical properties after mix with industrial mixer during the research, it was unexpectedly observed that whenever glass powder was incorporated in uhpc composition, with the substitution up to 100% of quartz powder the compressive strength increased about 40 mpa from 182 mpa (fig.4) (gp/gp0) to 221 mpa (gp/gp100). such enormous compressive strength could be obtained in each plant manufacturing concrete as long as it is equipped with advanced and sophisticated technology; however most producers unfortunately cannot afford such equipment. in order to prepare uhpc with standard mixers, the concrete particle size distribution was modified according to yu et al. (2010) recommendations and the water-to-cement ratio was increased up to 0.30. fig. 5. the compressive and flexural strength of uhpc with various amounts of micro steel fibres (w/c=0.30) 0 20 40 60 80 100 a m ou nt , % qp/gp0 qp/gp100 qp/gp10sf/gp100 sf/gp100 182 221 185 153 0 50 100 150 200 250 c om pr es si ve s tr en gh t, m pa qp/gp0 qp/gp100 qp/gp100sf/gp100 sf/gp100 116 139 143 149 6.7 13.2 23.5 36.2 0 5 10 15 20 25 30 35 40 0 20 40 60 80 100 120 140 160 180 200 0.0 73.5 110.3 147.0 fl ex ur al s tr en gh t, m pa c om pr es si ve s tr en gh t, m pa amount of micro steel fibres, kg/m3 1 quantitative and qualitative xrd analysis revealed that glass powder increases hydration process of portland cement. silica fume is almost 5 times more reactive comparing to glass powder. 2 silica fume can be completely eliminated from uhpc, and thus economical and ecologic effect can be achieved. 3 the designed concreted mixture is suitable for use in field conditions: high strength beams, slabs, columns and etc. conclusions alawode o, dip p. g, idowu o. i. (2011). effects of water-cement ratios on the compressive strength and workability of concrete and lateritic concrete mixes // the pacific journal of science and technology. 2011. vol 2 (2). p. 99-105. doi: no du h, tan k. h. use of waste glass as sand in mortar: part ii – alkali–silica reaction and mitigation methods // cement and concrete composites. 2013. vol. 35. p.118–26. http://dx.doi.org/10.1016/j. cemconcomp.2012.08.029 karakurt c, topçu i. b. effect of blended cements produced with natural zeolite and industrial by-products on alkali–silica reaction and sulfate resistance of concrete // construction and building materials. 2011. vol. 25. p. 1789–1795. http://dx.doi. org/10.1016/j.conbuildmat.2010.11.087 kou s. c, xing f. the effect of recycled glass powder and reject fly ash on the mechanical properties of fibre-reinforced ultrahigh performance concrete // advances in materials science and engineering. 2012. article id 263243: pages 8. http://dx.doi. org/10.1155/2012/263243 lin k. l, wang n. f, shie j. l, leec t. c, lee c. elucidating the hydration properties of paste containing thin film transistor liquid crystal display waste glass // journal of hazardous materials. 2008. vol. 159. p. 471–475. http://dx.doi.org/10.1016/j. jhazmat.2008.02.044 lst en 12390-4:2003. testing hardened concrete part 4: compressive strength specification for testing machines. lst en 12390-5:2009/p:2011. testing hardened concrete – part 5: flexural strength of test specimens. references 11 journal of sustainable architecture and civil engineering 2016/1/14 nguyen d. l, ryu g. s, koh k. t, kim d. j. size and geometry dependent tensile behavior of ultra-high-performance fiberreinforced concrete // composites. 2014. vol. 58. p. 279-292. doi:10.1016/j. compositesb.2013.10.072 saccani a, bignozzi m. c. asr expansion behavior of recycled glass fine aggregates in concrete // cement and concrete research. 2010. vol 40. p. 531–536. http://dx.doi.org/10.1016/j.cemconres.2009.09.003 schwarz n, neithalath n. influence of a fine glass powder on cement hydration: comparison to fly ash and modeling the degree of hydration // cement and concrete research. 2008. vol. 38. p. 429–436. http://dx.doi.org/10.1016/j.cemconres.2007.12.001 shafaatian s. m. h, akhavan a, maraghechi h, rajabipour f. howdoes fly ash mitigate alkali–silica reaction (asr) in accelerated mortar bar test (astm c1567)? // cement and concrete composites. 2013. vol. 37. p.143–153. http://dx.doi.org/10.1016/j.cemconcomp.2012.11.004. tavakoli d, heidari a. properties of concrete incorporating silica fume and nano-sio2 // indian journal of science and technology. 2013. vol 6(1). p. 108-112. doi: 10.17485/ijst/2013/v6i1/30569 wang h. y, huang w. l. durability of self-consolidating concrete using waste lcd glass // construction and building materials. 2010. vol. 24. p. 1008–1013. http://dx.doi.org/10.1016/j.conbuildmat.2009.11.018 yu r, spiesz p, brouwers h. j. h. mix design and properties assessment of ultra-high performance fibre reinforced concrete (uhpfrc) // cement and concrete research. 2014. vol. 56. p. 29-39. doi:10.1016/j.cemconres.2013.11.002 evaldas šerelis dr. kaunas university of technology, faculty of civil engineering and architecture, department of building materials main research area ultra-high performance concrete address studentų st. 48, lt-3031 kaunas, lithuania e-mail: evaldas.serelis@ktu.lt vitoldas vaitkevičius professor kaunas university of technology, faculty of civil engineering and architecture, department of building materials main research area ultra-high performance concrete, high strength concrete, secondary raw materials, concrete additives address studentų st. 48, lt-3031 kaunas, lithuania e-mail: vitoldas.vaitkevicius@ktu.lt vidas kerševičius dr. kaunas university of technology, faculty of civil engineering and architecture, department of building materials main research area ultra-high performance concrete, resistance of concrete to frost damage address studentų st. 48, lt-3031 kaunas, lithuania e-mail: vidas.kersevicius@ktu.lt about the authors journal of sustainable architecture and civil engineering 2016/1/14 44 journal of sustainable architecture and civil engineering vol. 1/ no. 14 / 2016 pp. 44-50 doi 10.5755/j01.sace.14.1.15066 © kaunas university of technology received 2016/03/30 accepted after revision 2016/06/29 a first attempt to determine the partial factors according to eurocodes for the verification of uls of steel elements for conditions of the republic of belarus jsace 1/14 a first attempt to determine the partial factors according to eurocodes for the verification of uls of steel elements for conditions of the republic of belarus *corresponding author: nadolskivv@mail.ru http://dx.doi.org/10.5755/j01.sace.14.1.15066 introduction vitali nadolski* republican unitary research enterprise for construction “institute belniis” (“institute belniis”, rue), 15 “b”, f.skoriny str. 220114 minsk, belarus viktar tur brest state technical university, faculty of civil engineering, moskovskaya 267, 224017, brest, republic of belarus the aim of the study is to develop science-based methodology for estimation the values of the partial factors for design of steel structures for the conditions of the republic of belarus, taking into account the specified values of reliability levels. the object of the study is steel structural elements. methods: mathematical modeling, numerical and analytical methods, parametric and graphic analysis. in january 2010 european standards (en standards, eurocodes) for the design, fabrication and erection of building structures were introduced in the republic of belarus. the system of european standards (en 1990) recognise the responsibility of regulatory authorities in each country and guarantee their right to determine values related to regulatory safety matters at national level. according to the reliability concept of building structures adopted in the standard iso 2394, en 1990 the target reliability levels for designed structures are set. it caused a necessity to calibrate the partial factors of steel structures for belarusian national annex to eurocode 3 based on the target reliability level using probabilistic methods. keywords: basic variable, partial factor, probabilistic models, limit state, target reliability level, structural reliability. the partial factor method (semiprobabilistic method), in which the variability and uncertainty of the design models and basic variables included in the design models are taken into account by means of the partial factor system applicable to the characteristic values of the basic variables has been widely practised. according to 6.1(1)p en 1990 (2002) the basic requirement of the partial factor method is as follows: “…it shall be verified that, in all relevant design situations, no relevant limit state is exceeded when design values for actions or effects of actions and resistances are used in the design models”. the partial factor system is one of the tools for differentiation and assurance of the target levels of the structural reliability; therefore, the justification of their values with due account to the specific geographic, social and economic conditions is a top-priority objective for every state. 45 journal of sustainable architecture and civil engineering 2016/1/14 the probabilistic models of the basis variables for the conditions of the republic of belarus the present investigation is devoted to the justification of values of the partial factors for the verification of ultimate limit states of steel elements for condition of the republic of belarus. the partial factors values are to be determined by the following methods: _ expert judgement; _ on the basis of the analysis of compliance with the many years’ experience and construction traditions; _ statistical methods, which are based on the required probability of design values of the basic variables; _ calibration with application of the probabilistic methods on the basis of the target (required) reliability level. the approach based on application of the probabilistic methods is the most advanced one making it possible to take into consideration the actual condition of service of the structures and requirements for them as well as to ascertain the scientifically grounded partial factors values. in the today’s regulations of the european union, usa, canada and other countries, the partial factors values are adopted according to the results of calibrations performed by the probabilistic methods (allen 1975, beck 2010, byfield 1996, ellingwood 1982). the main objective when determining the partial factors by the probabilistic method consists in assurance of the required reliability level. the next logic stage in regulation of the partial factors values consists in the calibration of the partial factors system, which is a norm optimisation issue. the calibrated partial factors shall ensure the reliability levels of the most typical structures to be as near to the target reliability levels as possible regardless the materials to be used, prevailing actions and environment conditions; here the number of the partial factors values is restricted. the general recommendations for calibration have the status of statutory norm in iso 2394 (2015) and en 1990(2002) and reflected in the jcss(2001). the procedure of calibration of the partial factors is described in the works gulvanessian (2002), sorensen (2001), vrouwenvelder (1987). given the probabilistic models of the basic variables, the failure probability for the basic period of time can be determined by the reliability theory methods. the calculated values of the failure probability are compared with the target reliability level. should the result be unsatisfactory, a new set of partial factors values shall be established and the calculation shall be repeated until the moment of achievement of the reliability level. the initial data for the probabilistic calculation is the information on the basic variables used in the performance functions, therefore the accuracy and adequacy of the probabilistic models of the variables exert predominating influence on the calculation results. this circumstance predetermines the necessity of the systemic investigations of the statistical parameters of the basic variables and formation of the unified principles of their assignment. in the next section the probabilistic models of the basis variables for the conditions of the republic of belarus are described. a special place is held by the matter of establishment of the probability distribution law for the basic variable. usually, the distribution law is established on the basis of the statistical analysis of the available experimental data. in the construction industry, the availability of experimental data is limited making it impossible to obtain the statistically valid results. therefore, theoretical preconditions are often used when choosing the distribution law. it should be noted that there is a general problem of use in the reliability theory of any of reliability random value distribution laws in the range of very low probability values, i.e. outside the range where the applicability of the law was experimentally justified and its parameters were determined. the general recommendations for assignment of the distribution laws to the basic variables have statutory form in the documents iso 2394 (2015), en 1990(2002) and jcss (2001). the probabilistic models of the basic variables adopted in various investigations differ often from each other. the reliability investigations based on different probabilistic models can lead to differjournal of sustainable architecture and civil engineering 2016/1/14 46 ent results and, as a consequence, to different values of the partial factors, combination factors and other parameters ensuring the achievement of the target reliability levels. it is important to take into account that the calibrated values of the reliability parameters belong to a specific set of probabilistic models of the basic variables included in the models of resistance and action effects. as noted in iso 2394(2015) “the use of calibrated values jointly with other models can cause the unintended high or low reliability levels”. probabilistic models for basic variables adopted in accordance with general guidelines jcss (2001) and for snow load model has been developed taking into account the relevant research for the territory of the republic of belarus tur (2008, 2009), territorial peculiarities supply rolled steel into the country are accounted for the strength characteristics nadolski (2014, 2015). a special kind of the basic variable represents the combined effect of several actions. in this article, these matters are not considered. table 1 presents the probabilistic models of the basic variables included in the design models of resistances and action effects when designing the steel structures, on the basis of which the investigations of the target values of the reliability index were performed and the partial factors values were obtained. table 1 probabilistic models of the basic variables for the conditions of the republic of belarus basic variables distribution µ/xk v steel element resistance lognormal 1.1 – 1.2 0.05 – 0.08 uncertainties of the resistance model lognormal 1.0 – 1.15 0.05 – 0.10 self-weight normal 1.0 0.03 – 0.06 permanent load normal 1.0 – 1.05 0.07 – 0.10 imposed load gumbel distribution 0.45 – 0.6 0.35 – 0.40 uncertainties of the imposed load model normal 1.0 0.10 snow load gumbel distribution 0.9 – 1.1 0.19 – 0.23 uncertainties of the snow load model normal 1.0 0.15 wind action gumbel distribution 1.0 – 1.1 0.17 – 0.20 uncertainties of the wind action model normal 0.8 0.30 uncertainties of the action effect model lognormal 1.0 0.10 on the basis of the values of the sensitivity factors obtained using the first-order reliability method (form) and with the adopted probabilistic models of the basic variables, the partial factors values ensuring the achievement of the target value of the reliability index bt = 3.8 for the reliability class rc 2 according to en 1990 (2002) were obtained. the values of the partial factors for the resistance (γm) as well as permanent (γg) and variable (gq) actions are presented in the following form: µ is the mean value; v is the coefficient of variation, and xk is the characteristic value. calibration of the partial factors in accordance with the reliability level specified by en 1990 standard where: grd is the partial factor taking into account the uncertainties of the resistance model; gm is the partial factor for the material property (yield strength of steel) taking into account the (1)γm = grd × gm , γg = gsd × gg , gq = gsd × gµ × gq , 47 journal of sustainable architecture and civil engineering 2016/1/14 (2) (3) fig. 1 and 2 presents the partial factors values gi depending on the load ratio χ = qk / (gk + qk) ensuring the achievement of the target value of the reliability index bt = 3.8. the results are presented for the imposed and snow loads only. the dependences gi – χ have similar nature when considering the wind load. for the purpose of the probabilistic description the mean values of the statistical parameters of basic variables were adopted from the range which is presented in table 1. such a presentation makes it possible to reflect the qualitative aspect of dependence under investigation. the obtained partial factors values are consistent with the results obtained by other investigators holicky (2009), sadovský (2006), sýkora(2011) . possibility of adverse deviation of the material property from its characteristic value; gsd is the partial factor taking into account the uncertainties of the action effect model; gg is the partial factor for the permanent load taking into account the possibility of adverse deviation of the permanent load from its representative value; gµ is the partial factor taking into account the uncertainties of the action model (for example, for the snow load this factor takes into account the uncertainty of the pattern of distribution of the snow load on the roof); gq is the partial factor for the variable action taking into account the possibility of adverse deviation of the variable action from its representative value. fig. 1 partial factors values ensuring the achievement of the target reliability index bt = 3.8 for the imposed load fig. 2 partial factors values ensuring the achievement of the target reliability index bt = 3.8 for the snow load the analysis of the partial factors values required for ensuring the reliability level specified in en 1990 (2002) standard has revealed inconsistencies in the reliability concept adopted in the eurocodes, namely: _ the obtained partial factors values exceed considerably those applied at present in the national and worldwide practice of normalising the variable actions; _ the numerical analysis of the prosperity of the design values of the basic variables has shown that the probability of exceeding the design values of the variable actions is at the level of 10-4…10-5. using the appropriate distribution law makes it possible to determine the prosperity of the design value. for example, adoption of the gumbel distribution for the snow load at the ground / gives the probability of exceeding the obtained design load value: where: rd is the partial factor taking into account the uncertainties of the resistance model; m is the partial factor for the material property (yield strength of steel) taking into account the possibility of adverse deviation of the material property from its characteristic value; sd is the partial factor taking into account the uncertainties of the action effect model; g is the partial factor for the permanent load taking into account the possibility of adverse deviation of the permanent load from its representative value; is the partial factor taking into account the uncertainties of the action model (for example, for the snow load this factor takes into account the uncertainty of the pattern of distribution of the snow load on the roof); q is the partial factor for the variable action taking into account the possibility of adverse deviation of the variable action from its representative value; fig. 1 and 2 presents the partial factors values i depending on the load ratio χ = qk / (gk + qk) ensuring the achievement of the target value of the reliability index t = 3.8. the results are presented for the imposed and snow loads only. the dependences i – χ have similar nature when considering the wind load. for the purpose of the probabilistic description the mean values of the statistical parameters of basic variables were adopted from the range which is presented in table 1. such a presentation makes it possible to reflect the qualitative aspect of dependence under investigation. the obtained partial factors values are consistent with the results obtained by other investigators holicky (2009), sadovský (2006), sýkora(2011) . fig. 1. partial factors values ensuring the achievement of the target reliability index t = 3.8 for the imposed load fig. 2. partial factors values ensuring the achievement of the target reliability index t = 3.8 for the snow load analysis of the partial factors values established based on the reliability level specified by en 1990 standard the analysis of the partial factors values required for ensuring the reliability level specified in en 1990 (2002) standard has revealed inconsistencies in the reliability concept adopted in the eurocodes, namely: – the obtained partial factors values exceed considerably those applied at present in the national and worldwide practice of normalising the variable actions; – the numerical analysis of the prosperity of the design values of the basic variables has shown that the probability of exceeding the design values of the variable actions is at the level of 10-4…10-5. using the appropriate distribution law makes it possible to determine the prosperity of the design value. for example, adoption of the gumbel distribution for the snow load at the ground / gives the probability of exceeding the obtained design load value: p = exp [ –exp [ –a (sd – b) ] ] (2) where: sd is the design value of the snow load at the ground: i  7 6 9 2 5 8 q g m 0.7 1.0 1.3 1.6 1.9 2.2 2.5 0 0.2 0.4 0.6 0.8 1.0 q g m i 0.7 1.0 1.3 1.6 1.9 2.2 2.5 0 0.2 0.4 0.6 0.8 1.0 where: rd is the partial factor taking into account the uncertainties of the resistance model; m is the partial factor for the material property (yield strength of steel) taking into account the possibility of adverse deviation of the material property from its characteristic value; sd is the partial factor taking into account the uncertainties of the action effect model; g is the partial factor for the permanent load taking into account the possibility of adverse deviation of the permanent load from its representative value; is the partial factor taking into account the uncertainties of the action model (for example, for the snow load this factor takes into account the uncertainty of the pattern of distribution of the snow load on the roof); q is the partial factor for the variable action taking into account the possibility of adverse deviation of the variable action from its representative value; fig. 1 and 2 presents the partial factors values i depending on the load ratio χ = qk / (gk + qk) ensuring the achievement of the target value of the reliability index t = 3.8. the results are presented for the imposed and snow loads only. the dependences i – χ have similar nature when considering the wind load. for the purpose of the probabilistic description the mean values of the statistical parameters of basic variables were adopted from the range which is presented in table 1. such a presentation makes it possible to reflect the qualitative aspect of dependence under investigation. the obtained partial factors values are consistent with the results obtained by other investigators holicky (2009), sadovský (2006), sýkora(2011) . fig. 1. partial factors values ensuring the achievement of the target reliability index t = 3.8 for the imposed load fig. 2. partial factors values ensuring the achievement of the target reliability index t = 3.8 for the snow load analysis of the partial factors values established based on the reliability level specified by en 1990 standard the analysis of the partial factors values required for ensuring the reliability level specified in en 1990 (2002) standard has revealed inconsistencies in the reliability concept adopted in the eurocodes, namely: – the obtained partial factors values exceed considerably those applied at present in the national and worldwide practice of normalising the variable actions; – the numerical analysis of the prosperity of the design values of the basic variables has shown that the probability of exceeding the design values of the variable actions is at the level of 10-4…10-5. using the appropriate distribution law makes it possible to determine the prosperity of the design value. for example, adoption of the gumbel distribution for the snow load at the ground / gives the probability of exceeding the obtained design load value: p = exp [ –exp [ –a (sd – b) ] ] (2) where: sd is the design value of the snow load at the ground: i  7 6 9 2 5 8 q g m 0.7 1.0 1.3 1.6 1.9 2.2 2.5 0 0.2 0.4 0.6 0.8 1.0 q g m i 0.7 1.0 1.3 1.6 1.9 2.2 2.5 0 0.2 0.4 0.6 0.8 1.0 analysis of the partial factors values established based on the reliability level specified by en 1990 standard p = exp [ –exp [ –a (sd – b) ] ] sd = sk × gq where: sd is the design value of the snow load at the ground: journal of sustainable architecture and civil engineering 2016/1/14 48 when describing the snow load at the ground by the gumbel distribution and with the values of the partial factor taking into account the load variability at the ground only γq (see formula 2), the probability of exceeding the design values was 10-5 per year. here it is necessary to keep in mind that the values of the variable actions are normalised from the distribution of the annual maxima. therefore such a probability is only applicable when normalising the rare natural and climatic phenomena or accidental value of the action and unacceptable for the design values of the variable actions when considering the permanent design situations. in addition, the fractile of this level requires the considerable extrapolation far beyond the observable values that causes uncertainties and reduce the trustworthiness of evaluation of the final result. in the revealed situation, the analysis of the structural reliability levels on the basis previous experience of standardization with the adopted probabilistic models of the basic variables. a and b are the distribution parameters to be determined through the mean value µ and standard deviation σ of the whole samples: (4) (5) a = π/ (σ √6) b = µ – 0.5772 / a as an alternative, the assessment of the reliability levels based on the previous experience of standardization for the belarus has been performed. the results are presented as diagrams where the reliability index values β are laid off as ordinates and the load ratio χ – as abscissas. fig.3 presents the upper and lower limits of variation of β under the simultaneous action of the permanent and imposed loads, and fig.4 – the same limits under action of the permanent and snow loads. the abrupt jump of the values β in fig.4 is conditioned by the change of the partial factor for the snow load according to the snip (1985). according to clause 5.7 snip (1985) the partial factor assessment of the reliability levels on the basis of the previous belarusian experience of standardization fig. 3 dependences of β – χ for the imposed load sd = sk × q (3) a and b are the distribution parameters to be determined through the mean value µ and standard deviation σ of the whole samples: a = π/ (σ √6) (4) b = µ – 0.5772 / a (5) when describing the snow load at the ground by the gumbel distribution and with the values of the partial factor taking into account the load variability at the ground only q (see formula 2), the probability of exceeding the design values was 105 per year. here it is necessary to keep in mind that the values of the variable actions are normalised from the distribution of the annual maxima. therefore such a probability is only applicable when normalising the rare natural and climatic phenomena or accidental value of the action and unacceptable for the design values of the variable actions when considering the permanent design situations. in addition, the fractile of this level requires the considerable extrapolation far beyond the observable values that causes uncertainties and reduce the trustworthiness of evaluation of the final result. in the revealed situation, the analysis of the structural reliability levels on the basis previous experience of standardization with the adopted probabilistic models of the basic variables. assessment of the reliability levels on the basis of the previous belarusian experience of standardization as an alternative, the assessment of the reliability levels based on the previous experience of standardization for the belarus has been performed. the results are presented as diagrams where the reliability index values β are laid off as ordinates and the load ratio χ – as abscissas. fig.3 presents the upper and lower limits of variation of β under the simultaneous action of the permanent and imposed loads, and fig.4 – the same limits under action of the permanent and snow loads. the abrupt jump of the values β in fig.4 is conditioned by the change of the partial factor for the snow load according to the snip (1985). according to clause 5.7 snip (1985) the partial factor s* for snow load for roof members is s* = 1.5 for gk* / sk* ≥ 0.8 and s* = 1.6 for gk* / sk* < 0.8. the partial factor s* changes at χ  0.58 that corresponds to gk* / sk* = 0.8. where the parameters defined in snip (1985) are denoted by the symbol «*». symbols gk* and sk* represent characteristic values of permanent and snow load, respectively. the similar results of the analysis of the reliability indices for the russian federation (sykora 2014) should also be noted. fig. 3. dependences of β – χ for the imposed load fig. 4. dependences of β – χ for the snow load 0 0.2 0.4 0.6 0.8 11.0 1,5 2.0 2.5 3.0 3.5   0 0.2 0.4 0.6 0.8 11.0 1,5 2.0 2.5 3.0 3.5   sd = sk × q (3) a and b are the distribution parameters to be determined through the mean value µ and standard deviation σ of the whole samples: a = π/ (σ √6) (4) b = µ – 0.5772 / a (5) when describing the snow load at the ground by the gumbel distribution and with the values of the partial factor taking into account the load variability at the ground only q (see formula 2), the probability of exceeding the design values was 105 per year. here it is necessary to keep in mind that the values of the variable actions are normalised from the distribution of the annual maxima. therefore such a probability is only applicable when normalising the rare natural and climatic phenomena or accidental value of the action and unacceptable for the design values of the variable actions when considering the permanent design situations. in addition, the fractile of this level requires the considerable extrapolation far beyond the observable values that causes uncertainties and reduce the trustworthiness of evaluation of the final result. in the revealed situation, the analysis of the structural reliability levels on the basis previous experience of standardization with the adopted probabilistic models of the basic variables. assessment of the reliability levels on the basis of the previous belarusian experience of standardization as an alternative, the assessment of the reliability levels based on the previous experience of standardization for the belarus has been performed. the results are presented as diagrams where the reliability index values β are laid off as ordinates and the load ratio χ – as abscissas. fig.3 presents the upper and lower limits of variation of β under the simultaneous action of the permanent and imposed loads, and fig.4 – the same limits under action of the permanent and snow loads. the abrupt jump of the values β in fig.4 is conditioned by the change of the partial factor for the snow load according to the snip (1985). according to clause 5.7 snip (1985) the partial factor s* for snow load for roof members is s* = 1.5 for gk* / sk* ≥ 0.8 and s* = 1.6 for gk* / sk* < 0.8. the partial factor s* changes at χ  0.58 that corresponds to gk* / sk* = 0.8. where the parameters defined in snip (1985) are denoted by the symbol «*». symbols gk* and sk* represent characteristic values of permanent and snow load, respectively. the similar results of the analysis of the reliability indices for the russian federation (sykora 2014) should also be noted. fig. 3. dependences of β – χ for the imposed load fig. 4. dependences of β – χ for the snow load 0 0.2 0.4 0.6 0.8 11.0 1,5 2.0 2.5 3.0 3.5   0 0.2 0.4 0.6 0.8 11.0 1,5 2.0 2.5 3.0 3.5   γs * for snow load for roof members is γs * = 1.5 for gk * / sk * ≥ 0.8 and gs * = 1.6 for gk * / sk * < 0.8. the partial factor γs * changes at χ ≈ 0.58 that corresponds to gk * / sk * = 0.8. where the parameters defined in snip (1985) are denoted by the symbol «*». symbols gk * and sk * represent characteristic values of permanent and snow load, respectively. the similar results of the analysis of the reliability indices for the russian federation (sykora 2014) should also be noted. on the basis of the analysis of the results of investigations of the reliability levels ensured by the previous practice of standardization and designing of steel structures, the least value of the failure probability pf = 10 -2 for the assignment period of 50 years was adopted for the further calibration of the partial factors. fig. 4 dependences of β – χ for the snow load 49 journal of sustainable architecture and civil engineering 2016/1/14 for purposes calibration the partial factors the probabilistic models of basic variables included in the model of resistance of steel elements are developed for the republic of belarus. reasonable probabilistic models of resistance and action effects are allowed to calibrate values of the partial factors for design models of steel structures for a target reliability level of building structures according to eurocodes. the further analysis showed that the use of the obtained value of the partial factors leads to probability of exceeding (the fractile of annual extremes) the design values more than for accident load. the way out of this situation is the revision of the numerical values of the parameters of reliability or a slightly different approach to the design reliability. this made it necessary to carry out an assessment of reliability parameters on the basis of previous experience of standardization. the numerical values of the reliability levels of steel structures have been obtained based on the previous normalising experience as applied to the conditions of the republic of belarus. when performing the verification of the ultimate limit states of the steel elements of the mean reliability class (residential or office buildings, etc.), the minimum value of the failure probability for the assignment period of 50 years is recommended to be pf = 10 -2 for the adopted probabilistic models of the basic variables. the results can be applied in the development of the provisions of the norms relating to the project to ensure the reliability of structures, as well as allow you to perform probabilistic calculations of steel structures. it is expected 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(eds.), supplement to the proceedings of the european safety and reliability conference esrel 2009, prague, czech republic, 7 10 september 2009. ostrava: všb technical university of ostrava, 2009; 23-30. iso 2394:2015. general principles on reliability for structures. jcss probabilistic model code //joint committee of structural safety[electronic resource]. 2001. mode of access: http://www.jcss.ethz.ch. –date of access: 15.01.2012. martynov i., nadolski v. статистические параметры базисных переменных, входящих в модели сопротивления стального элемента [the statistical parameters of basic variables in the resistance model of steel element]. архитектура и строительные науки. 2014; 1, 2(18, 19): 39-41 nadolski v., martynov i. вероятностные модели сопротивления стальных элементов [probabilistic modeling of resistance of steel elements] вестник полоцкого государственного университета. – серия f: прикладные науки. строительство. 2015; 8: 44–49. conclusions references journal of sustainable architecture and civil engineering 2016/1/14 50 nadolski v., sykora, m. uncertainty in resistance models for steel members. transactions of the vsb technical university of ostrava. 2014. construction series 14/2: 26–37. http://dx.doi.org/10.2478/tvsb-2014-0028 sadovský, z. climatic loads and reliability of light roof industrial buildings. safety and reliability for managing risk k – guedes soares & zio (eds) 2006 taylor & francis group, london, isbn 0-41541620-5 snip 2.01.07-85 nagruzki i vozdejstvija [construction norms and rules snip 2.01.07-85. loads and actions]. moscow, ministry of regional development, 1985. sorensen j.d., hansen s.o., nielsen t. arnbjerg. calibration of partial safety factors for danish structural codes. proc. iabse conf. safety, risk and reliability—trends in engineering. – zurich, 2001; 179–184. sýkora m., holický m. comparison of load combination models for probabilistic calibrations. in faber m.h., köhler j., nishijima k. 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(eds.) reliability engineering proceedings of the international workshop on reliability engineering and risk management iwrerm 2008, shanghai, 21 23 august 2008. shanghai: tongji university press, 2009; 183-188. tur v., markouski, d.m. 2009. калибровка значений коэффициентов сочетаний для воздействий при рас-четах железобетонных конструкций в постоянных и особых расчетных ситуациях [calibration of load combination factors used in design of reinforced concrete structures in persistent and accidental design situations]. строительная наука и техника, 2009; 2 (23): 32–48. tur v., valuev v., derechennik s., meshik o., voskoboynikov i. нормирование снеговых нагрузок для территории республики беларусь [normalization snow loads for the territory of the republic of belarus]. строительная наука и техника, 2008; 2: 27–45. vrouwenvelder a.c.w.m., siemes a.j.m. probabilistic calibration procedure for the derivation of partial safety factors for the netherlands building codes. delft university of technology, 1987; 32 (4): 9-29. vitali nadolski associate professor, scientific secretary republican unitary research enterprise for construction “institute belniis” main research area reliability of building steel structures, methods of checking the stability of steel structures address 15 “b”, f.skoriny str., 220114, minsk, belarus tel. +375 17 267 10 01 e-mail: csc@belniis.by viktar tur professor, head of the department brest state technical university, department "technology of concrete and building materials" main research area self-stressed structures, reliability of building structures address 267, moskovskaya str., 224017, brest, belarus tel. + 375 162 42 23 70 e-mail: vvtur@bstu.by about the authors 39 journal of sustainable architecture and civil engineering 2018/1/22 *corresponding author: wojciech.kubissa@pw.edu.pl utilisation of copper slag waste and heavy-weight aggregates for production of pre-cast shielding concrete elements received 2018/01/22 accepted after revision 2018/05/31 journal of sustainable architecture and civil engineering vol. 1 / no. 22 / 2018 pp. 39-47 doi 10.5755/j01.sace.22.1.20006 © kaunas university of technology utilisation of copper slag waste and heavy-weight aggregates for production of pre-cast shielding concrete elements jsace 1/22 http://dx.doi.org/10.5755/j01.sace.22.1.20006 wojciech kubissa*, roman jaskulski faculty of civil engineering, mechanics and petrochemistry, warsaw university of technology 17 łukasiewicza st., 09-400 płock, poland pui-lam ng faculty of civil engineering, vilnius gediminas technical university sauletekio ave. 11, lt-10223 vilnius, lithuania jiajian chen department of civil engineering, foshan university, 528000 foshan, china concrete as a versatile building material can provide physical and biological shielding against ionizing radiation. in addition to nuclear reactor covers, facilities requiring radiation protection are radiological and x-ray laboratories in hospitals or health centres. the function of radiation protection can be met by heavy-weight concrete, whose shielding properties are largely derived from the high-density aggregates. one of the possible construction methods of shielding walls in healthcare buildings is the use of pre-cast concrete blocks. for this purpose, research on a concrete having a density in the air-dry state of higher than 3200 kg/m3 using barite, magnetite and basalt as coarse aggregate and copper slag waste (from by-product of the process of copper extraction by smelting) as fine aggregate has been performed. the copper slag waste has been used, among others, as an abradant in the surface sandblasting process but after such usage it is considered to be a waste and as indicated by pilot research, it can be a good substitute for sand in concrete. mechanical properties, water absorption and sorptivity of heavy-weight concrete so produced were compared with reference concrete prepared with crushed amphibolite as coarse aggregate and quartz sand as fine aggregate. the suitability of copper slag waste for making small pre-cast shielding concrete elements is confirmed. the compressive strength of heavy-weight concrete mixtures with copper slag waste was sufficient for the intended applications. the copper slag concrete had lower water absorption and sorptivity than concrete prepared with sand. an economic analysis of the costs of producing concrete with a density higher than 3200 kg/m3 with or without copper slag waste showed that the copper slag concrete, regardless of the type of heavy-weight aggregate used, is clearly more economical than the concrete of the compositions reported in the literature containing similar coarse aggregates and sand as the fine aggregate. keywords: amphibolite, barite, basalt, copper slag, heavy-weight aggregate, magnetite, shielding concrete. journal of sustainable architecture and civil engineering 2018/1/22 40 introduction concrete, because of its characteristics and ease of shaping into variable forms, is a versatile building material that can act as physical and biological shield against ionizing radiation (glinicki 2015, piotrowski and gryziński 2016). at the same time the shielding concrete can fulfil structural functions. in addition to reactor covers, enclosures and other applications in nuclear power plants, facilities requiring radiation protection are radiological and x-ray laboratories in hospitals or health centres. the function of radiation protection (in the latter case mainly x-ray) can be met by heavy-weight concrete. shields made of heavy-weight concrete are described as a passive protection, for which a typical purpose is to reduce the level of radiation to levels safe for the operational personnel and users in the premises (saferna and kaszuba 2003, ouda 2015). the criteria for selection of ingredients and concrete mix design for shielding structures include effectiveness of shielding against ionizing radiation, mechanical and physical properties, and impermeability to liquids and gases (bamonte and gambarova 2014, kurtis et al. 2017). the significance of cement selection for radiation shielding concrete was discussed by baran et al. (2016). the permeability requirement of the shielding concrete is dependent on the applications. for example, the impermeability is particularly important in the case of a nuclear power plant where the leakage of radioactive gases must be protected against. for other applications, the low permeability of concrete, especially regarding to liquids, helps to prevent the penetration of harmful substances into and out of the structures. the compressive strength requirement of the shielding concrete is generally not high, it is often the class c20/25 or c25/30 according to european standard en 206 (saferna and kaszuba 2003). to manufacture shielding concrete, usually special heavy aggregates such as barite, magnetite or hematite are used (brandt 2013). these special aggregates, generally made of soft rocks, have sometimes unfavourable gradation and a high content of dust. this causes an increase of water demand and technological difficulties in the manufacturing and compaction of concrete mixes (glinicki 2015). there is also a risk of segregation of the components of the mixture alongside its production, transport or compaction (aci 221r-96 1997, aci 304.3r-96 2004, glinicki 2015). possible segregation of concrete components could result in significant non-uniformity and heterogeneity which can lead to local radiation surges and failure of shielding. one of the possible solutions for the construction of shielding walls in healthcare buildings is the use of pre-cast concrete blocks. in the case of a structure with uncomplicated shape, such as a planar shielding wall, the use of small prefabricated elements allows higher flexibility in concrete placement, transportation and on-site handling. concrete mix can be designed to have even a higher consistency, compared to the case of ready-mixed concrete that needs to cater for the transport, pumping and in-situ casting of monolithic walls. the pre-cast method limits the risk of segregation of the mixture components during placement and compaction. the use of pre-cast blocks also allows for faster wall construction than in-situ concreting. the wall built from the blocks can be dismantled with relative ease and this allows the material to be re-used elsewhere. fine aggregate used in the shielding concrete is often sand, whose density is substantially lower than the density of the heavy aggregates used as coarse aggregate. to minimise the segregation risk, theoretically it is more appropriate to use fine aggregate of higher density. a viable solution would be the use of copper slag, which has a higher density than sand (approximately 3000 kg/m3). copper slag is a by-product during the process of copper extraction by smelting. it is a nearly inert material in concrete and its physical properties are similar to natural sand (meenakshi sudarvizhi and ilangovan 2011). it is used, among others, as an abradant in the surface sand-blasting process but after such usage it is considered to be a waste. as indicated by pilot research, copper slag should be a good substitute for sand in concrete (ayano and sakata 2000, al-jabri et al. 2011, alp et al. 2008, kubissa et al. 2017). it is possible to utilise waste copper slag 41 journal of sustainable architecture and civil engineering 2018/1/22 for the production of high-quality concrete, improving its properties compared to concrete batched with sand (al-jabri et al. 2009, ambily et al. 2015). due to mechanical abrasion, the copper slag particle size after surface blast-cleaning process becomes finer. the content of 0 – 0.125 mm and 0.125 – 0.25 mm fractions is significantly increased. typically the waste copper slag also contains a small amount of corrosion products and corrosion protection coatings (rzechuła 1994). the copper slag could potentially enhance the abrasion resistance of concrete, though the abrasion resistance of pre-cast blocks is not of prime importance. nevertheless, for shielding concrete which is subjected to abrasive degradation, the abrasion resistance improvement by copper slag would be important from durability viewpoint. an example of the use of heavy-weight concrete requiring abrasion resistance is containers for transporting radioactive waste. the purpose of the research undertaken by the authors is to develop a concrete having a density in the air-dry state of higher than 3200 kg/m3 using barite, magnetite and basalt as coarse aggregate and copper slag as fine aggregate. mechanical properties and sorptivity of such heavy concretes were compared with reference concrete prepared with coarse amphibolite aggregate and sand. to test the impact of copper slag addition, and to study the change of mixture consistency, the concrete with amphibolite and copper slag was also prepared. consistency of this concrete was similar to concrete with barite and magnetite/basalt aggregates. materialsportland cement cem i 42.5r complying to european standard en 197 supplied by górażdże ce-ment plant was used. the following types of coarse aggregates were used: _ magnetite aggregate with 0-16 mm fraction (4800 kg/m3 in density), _ barite aggregate with 0-16 mm fraction (4200 kg/m3 in density), _ basalt aggregate with 8-16 mm fraction (2900 kg/m3 in density), _ amphibolite aggregate (for reference concrete) with 2-8 mm and 8-16 mm fractions (2900 kg/m3 in density). as fine aggregate, sand and copper slag of 0 – 2 mm size fraction were used. aggregate crushing value (acv) of coarse aggregate was determined in accordance with polish standard pn-b-06714-40:1978 (similar to british standard bs 812-110:1999 but with metrical set of sieves). crushing resistance of the coarse aggregates was as follows: for barite, the acv was 25.60 for 4 – 8 mm fraction and 36.04 for 8 – 16 mm fraction; for magnetite, the acv was 6.10 for 4 – 8 mm fraction and 6.37 for 8-16 mm fraction; for amphibolite, the acv was 2.66 for 4 – 8 mm fraction and 5.07 for 8 – 16 mm fraction; for basalt, the acv was 1.97 for 8 – 16 mm fraction. a higher value of acv implies a lower crushing resistance. in the design of concrete mixes, a constant amount of cement 300 kg/m3 was used, and the water to cement ratio (w/c) was 0.48. superplasticizer chryso optima 100 was used with the dosage of 1.0% to 1.5% by mass of cement. the composition of the concrete mixtures is given in table 1. in the table, the mixture labelled m contained magnetite and basalt coarse aggregate and copper slag as fine aggregate, the mixture labelled ba contained barite coarse aggregate and copper slag as fine aggregate, the mixture labelled r-p contained amphibolite coarse aggregate and sand as fine aggregate, and the mixture labelled r-cs contained amphibolite coarse aggregate and copper slag as fine aggregate. the consistency was measured in terms of the cone slump value and bulk density of the mixtures was determined by standard methods. with the exception of mixture r-p, the slump value was low. this is acceptable as the concrete mixes are designated for the manufacturing of small pre-cast elements, where high workability is not required. a significant difference in the consistency of concrete mixtures r-p and r-cs is caused by a much higher content of fine particles in the copper slag. journal of sustainable architecture and civil engineering 2018/1/22 42 table 1 composition [kg/m3] of concrete mixes components mixture id m ba r-p r-cs cement cem i 42.5 300 300 300 300 sand 0-2 mm --661 -copper slag 0-2 mm 678 441 -745 amphibolite 2-8 mm --504 504 amphibolite 8-16 mm --965 963 magnetite 0-16 mm 1978 ---barite 0-16 mm -2557 --basalt 8-16 mm 340 ---water 144 144 144 144 superplasticizer 3.0 3.0 3.0 4.5 mix parameter and properties w/c ratio 0.48 0.48 0.48 0.48 bulk density [kg/m3] 3444 3445 2578 2660 slump [mm] 10 10 190 10 compressive and tensile splitting strength test the compressive strength test was conducted on 100 mm cube specimens after 28 days of hardening. the measurements were carried out in accordance with european standard en 123903. the tensile splitting strength test was conducted for the same type of specimens in accordance with european standard en 12390-6. both tests were performed using a compression machine tonitechnik tonipact ii with 3000 kn capacity. the rate of loading was controlled at 0.5 mpa/s for compressive strength test and 0.05 mpa/s for splitting test. sorptivity test and free water absorption measurement the sorptivity test was conducted on the halves of cubic specimens of 100 mm edge by means of the mass measurement method. at first the specimens had been saturated with water for about 14 days, then their surfaces were wiped dry and weighed, and subsequently oven-dried to stable mass at the temperature of about 105°c. the mass differences were determined to calculate the values of free water absorption. the measurements of sorptivity were conducted at the temperature of approximately 20°c. the specimens were weighed and then placed in the vessel with water, where the specimens were dipped up to the depth of 3 mm. in specific time intervals from the beginning of the test, the specimens were wiped to be surface dry and weighed again to define their weight gain resulting from water absorption. subsequent weight measurements were conducted for 6 hours. the sorptivity s in g/(cm2·h0.5) was defined as the slope of the linear function expressing the dependence of the mass of water absorbed ∆m by the area f on the time root t0.5 (eq. 1) (kubissa and jaskulski 2013): methods 5.0ts f m ⋅= ∆ (1) 43 journal of sustainable architecture and civil engineering 2018/1/22 (2) d ds m mm n   x100% (2) 146 where: 147 n free water absorption [%], 148 ms mass of a fully soaked specimen [g], 149 md mass of a specimen dried to stable mass [g]. 150 the mass of a fully soaked specimen was measured after 28-days curing in water. 151 152 bohme abrasion test the test was performed according to polish standard pn-en 1340. for each concrete mix, four 153 70×70×70 mm specimens were tested. specimens were obtained by sawing the 150 mm cubes, and the tests were carried 154 out between 40 and 45 days after concreting. just before the test the specimens were dried in an oven at 105°c to stable 155 mass. the specimens were then weighed at 0.1 g accuracy and the thickness in nine points was measured before and after 156 the abrasion procedure. 157 results 158 the test results are presented in table 2. in the table, each value is an average of six measurements. confidence 159 intervals were also provided with a confidence factor of 0.95. in analysis of the results, the mixture r-p with amphibolite 160 coarse aggregate and sand as fine aggregate was used as the reference concrete. 161 162 table 2. test results 163 properties mixture id m ba r-p r-cs compressive strength fc at 28d [mpa] 37.9±2.2 39.2±2.4 43.3±4.5 50.3±2.2 compressive strength fc at 90d [mpa] 52.4±4.0 48.7±2.8 52.0±2.8 65.0±3.0 tensile strength ft at 28d [mpa] 2.82±0.37 2.42±0.17 3.86±0.22 3.86±0.09 water absorption [%] 3.36±0.07 3.06±0.08 4.34±0.11 3.96±0.09 sorptivity s [cm/h0.5] 0.035±0.003 0.034±0.004 0.083±0.003 0.041±0.004 bohme abrasion [mm] 4.43±0.27 8.33±0.46 2.57±0.32 2.64±0.32 porosity (calculated) [%] 11.2±0.22 10.2±0.25 10.7±0.27 10.1±0.22 164 the compressive strength of the reference concrete after 28 days was 43.3 mpa. by replacing sand with copper slag, 165 mixture r-cs (concrete with amphibolite coarse aggregate and copper slag as fine aggregate) had a higher strength by 166 16.2%. the heavy-weight concrete mixtures m and ba had lower 28-day compressive strength than the reference. the 167 percentage differences were 9.3% for mixture ba (concrete with barite aggregate) and 12.5% for mixture m (concrete with 168 magnetite and basalt aggregate). nevertheless, the strength of heavy-weight concrete for both mixtures m and ba was 169 sufficient for the intended applications. the increase in compressive strength at the age of 90 days compared to the strength 170 at 28 days was 38.3%, 24.2%, 20.1%, 29.2% for concrete mixtures m, ba, r-p, r-cs respectively. the increase in 171 compressive strength would be due to the hydration of unhydrated cement beyond the 28-day age, as well as the limited 172 pozzolanic reactivity of copper slags. the 90-day compressive strength of the reference concrete was 52.0 mpa. 173 comparatively, mixture r-cs had a higher strength by 25.0%. the heavy-weight concrete with barite had lower 90-day 174 strength than the reference, with a percentage difference of 6.3%. the 90-day strength of heavy-weight concrete with 175 magnetite and basalt aggregate was 0.8% higher than the reference. 176 the tensile strength of concrete with amphibolite coarse aggregate, regardless of the type of fine aggregate was the 177 same and was equal to 3.86 mpa. the strength of the concrete with magnetite/basalt and barite coarse aggregate were lower 178 by 26.9% and 37.3%, respectively. 179 the sorptivity of the reference concrete was 0.083 cm/h0.5, which allows to classify it as “good” according to the 180 criteria for the classes of durability given in kubissa (2016). sorptivity of concrete with copper slag was much lower. the 181 percentage differences were 50.6% for concrete mixture r-cs with amphibolite and 57.8% and 59.0% for concrete mixtures 182 m and ba with magnetite/basalt and barite aggregates, respectively. the values obtained from these concrete mixtures 183 determine their durability class as “very good”. 184 the water absorption of the reference concrete was 4.34%. water absorption of concrete with copper slag was lower. 185 the percentage difference for concrete mixture r-cs with amphibolite aggregate was 8.8%, while the water absorption of 186 heavy-weight concrete mixtures m and ba was 22.5% and 29.6% lower than the reference concrete, respectively. the much 187 where: n – free water absorption [%], ms – mass of a fully soaked specimen [g], md – mass of a specimen dried to stable mass [g]. the free water absorption is calculated on the basis of (eq. 2): the mass of a fully soaked specimen was measured after 28 days curing in water. bohme abrasion test the test was performed according to polish standard pn-en 1340. for each concrete mix, four 70×70×70 mm specimens were tested. specimens were obtained by sawing the 150 mm cubes, and the tests were carried out between 40 and 45 days after concreting. just before the test the specimens were dried in an oven at 105°c to stable mass. the specimens were then weighed at 0.1 g accuracy and the thickness in nine points was measured before and after the abrasion procedure. the test results are presented in table 2. in the table, each value is an average of six measurements. confidence intervals were also provided with a confidence factor of 0.95. in analysis of the results, the mixture r-p with amphibolite coarse aggregate and sand as fine aggregate was used as the reference concrete. results table 2 test resultsproperties mixture id m ba r-p r-cs compressive strength fc at 28d [mpa] 37.9±2.2 39.2±2.4 43.3±4.5 50.3±2.2 compressive strength fc at 90d [mpa] 52.4±4.0 48.7±2.8 52.0±2.8 65.0±3.0 tensile strength ft at 28d [mpa] 2.82±0.37 2.42±0.17 3.86±0.22 3.86±0.09 water absorption [%] 3.36±0.07 3.06±0.08 4.34±0.11 3.96±0.09 sorptivity s [cm/h0.5] 0.035±0.003 0.034±0.004 0.083±0.003 0.041±0.004 bohme abrasion [mm] 4.43±0.27 8.33±0.46 2.57±0.32 2.64±0.32 porosity (calculated) [%] 11.2±0.22 10.2±0.25 10.7±0.27 10.1±0.22 the compressive strength of the reference concrete after 28 days was 43.3 mpa. by replacing sand with copper slag, mixture r-cs (concrete with amphibolite coarse aggregate and copper slag as fine aggregate) had a higher strength by 16.2%. the heavy-weight concrete mixtures m and ba had lower 28-day compressive strength than the reference. the percentage differences were 9.3% for mixture ba (concrete with barite aggregate) and 12.5% for mixture m (concrete with magnetite and basalt aggregate). nevertheless, the strength of heavy-weight concrete for both mixtures m and ba was sufficient for the intended applications. the increase in compressive strength at the age of 90 days compared to the strength at 28 days was 38.3%, 24.2%, 20.1%, 29.2% for concrete mixtures m, ba, r-p, r-cs respectively. the increase in compressive strength would be due to the hydration of unhydrated cement beyond the 28-day age, as well as the limited pozzolanic reactivity of copper slags. the 90-day compressive strength of the × 100 % journal of sustainable architecture and civil engineering 2018/1/22 44 reference concrete was 52.0 mpa. comparatively, mixture r-cs had a higher strength by 25.0%. the heavy-weight concrete with barite had lower 90-day strength than the reference, with a percentage difference of 6.3%. the 90-day strength of heavy-weight concrete with magnetite and basalt aggregate was 0.8% higher than the reference. the tensile strength of concrete with amphibolite coarse aggregate, regardless of the type of fine aggregate was the same and was equal to 3.86 mpa. the strength of the concrete with magnetite/ basalt and barite coarse aggregate were lower by 26.9% and 37.3%, respectively. the sorptivity of the reference concrete was 0.083 cm/h0.5, which allows to classify it as “good” according to the criteria for the classes of durability given in kubissa (2016). sorptivity of concrete with copper slag was much lower. the percentage differences were 50.6% for concrete mixture r-cs with amphibolite and 57.8% and 59.0% for concrete mixtures m and ba with magnetite/ basalt and barite aggregates, respectively. the values obtained from these concrete mixtures determine their durability class as “very good”. the water absorption of the reference concrete was 4.34%. water absorption of concrete with copper slag was lower. the percentage difference for concrete mixture r-cs with amphibolite aggregate was 8.8%, while the water absorption of heavy-weight concrete mixtures m and ba was 22.5% and 29.6% lower than the reference concrete, respectively. the much lower water absorption and sorptivity of mixtures m, ba and r-cs than reference mixture r-p is believed to be due to the absence of sand, which absorbs water. the comparatively even lower water absorption and sorptivity of mixtures m and ba than mixture r-cs is believed to be due to the water absorption of magnetite and barite aggregates (about 0.2%) are lower than that of amphibolite and basalt aggregate (about 0.5%). porosity of the concrete was calculated on the basis of free water absorption results and density measurements. the porosity of mixture m was 4.67% higher than the reference. the porosity of mixture r-cs and ba were lower than the reference. the percentage differences were 5.60% for concrete mixture r-cs with amphibolite and 4.67% for concrete mixture ba with barite aggregate, respectively. nevertheless, it is noted that the percentage differences in porosity are much lower than the percentage differences in water absorption. the reference concrete had the highest bohme abrasion resistance. the decrease in sample height during the test was 2.58 mm. concrete mixture r-cs had a comparable abrasion resistance to the reference, with a percentage difference of 2.7%. the heavy-weight concrete mixtures m and ba had significantly lower abrasion resistance than the reference with the percentage differences being 72.4% and 224.1%, respectively. however, there was no apparent correlation between the aggregate acv and the concrete abrasion resistance. discussion with reference to the results of acv reported above, the heavy-weight aggregates had relatively low resistance to crushing. for example, acv values of barite are higher than reported values of typical virgin rock aggregates and recycled aggregates (koper et al. 2015, jaskulski et al. 2017). this means the barite coarse aggregate had lower crushing resistance than typical virgin rock and recycled aggregates. acv values for magnetite are lower than those of barite, but are still considerably higher than the reported value of typical good quality virgin rock aggregates. the low crushing resistance of heavy-weight aggregate might result in lower mechanical properties of shielding concrete compared to reference concrete, and this may affect the compressive and tensile strength as well as the abrasion resistance. the test results suggest that the compressive strength is closely related to the abrasion resistance of the aggregate and concrete. 45 journal of sustainable architecture and civil engineering 2018/1/22 an economic analysis of the costs of producing concrete with a density higher than 3200 kg/m3 with or without copper slag is carried out. it was assumed that the price of cement is 95 eur/ton, the price of barite is 180 eur/ton, and the price of magnetite is 260 eur/ton (brandt et al. 2014). the cost of sand was taken as 7 eur/ton, and price of basalt aggregate is 17 eur/ton. in addition to the concrete mixes produced in this study, compositions of other heavy-weight concrete mixes from the literature (lim 1971, saferna and kaszuba 2003, ouda 2015, dąbrowski et al. 2016, kubissa and glinicki 2017) are included for comparison. fig. 1 concrete price plotted against concrete density index lower water absorption and sorptivity of mixtures m, ba and r-cs than reference mixture r-p is believed to be due to the 188 absence of sand, which absorbs water. the comparatively even lower water absorption and sorptivity of mixtures m and ba 189 than mixture r-cs is believed to be due to the water absorption of magnetite and barite aggregates (about 0.2%) are lower 190 than that of amphibolite and basalt aggregate (about 0.5%). 191 porosity of the concrete was calculated on the basis of free water absorption results and density measurements. the 192 porosity of mixture m was 4.67% higher than the reference. the porosity of mixture r-cs and ba were lower than the 193 reference. the percentage differences were 5.60% for concrete mixture r-cs with amphibolite and 4.67% for concrete 194 mixture ba with barite aggregate, respectively. nevertheless, it is noted that the percentage differences in porosity are much 195 lower than the percentage differences in water absorption. 196 the reference concrete had the highest bohme abrasion resistance. the decrease in sample height during the test 197 was 2.58 mm. concrete mixture r-cs had a comparable abrasion resistance to the reference, with a percentage difference of 198 2.7%. the heavy-weight concrete mixtures m and ba had significantly lower abrasion resistance than the reference with the 199 percentage differences being 72.4% and 224.1%, respectively. however, there was no apparent correlation between the 200 aggregate acv and the concrete abrasion resistance. 201 discussion 202 with reference to the results of acv reported above, the heavy-weight aggregates had relatively low resistance to 203 crushing. for example, acv values of barite are higher than reported values of typical virgin rock aggregates and recycled 204 aggregates (koper et al. 2015, jaskulski et al. 2017). this means the barite coarse aggregate had lower crushing resistance 205 than typical virgin rock and recycled aggregates. acv values for magnetite are lower than those of barite, but are still 206 considerably higher than the reported value of typical good quality virgin rock aggregates. the low crushing resistance of 207 heavy-weight aggregate might result in lower mechanical properties of shielding concrete compared to reference concrete, 208 and this may affect the compressive and tensile strength as well as the abrasion resistance. the test results suggest that the 209 compressive strength is closely related to the abrasion resistance of the aggregate and concrete. 210 211 212 fig. 1. concrete price plotted against concrete density index 213 an economic analysis of the costs of producing concrete with a density higher than 3200 kg/m3 with or without 214 copper slag is carried out. it was assumed that the price of cement is 95 eur/ton, the price of barite is 180 eur/ton, and the 215 price of magnetite is 260 eur/ton (brandt et al. 2014). the cost of sand was taken as 7 eur/ton, and price of basalt 216 aggregate is 17 eur/ton. in addition to the concrete mixes produced in this study, compositions of other heavy-weight 217 concrete mixes from the literature (lim 1971, saferna and kaszuba 2003, ouda 2015, dąbrowski et al. 2016, kubissa and 218 glinicki 2017) are included for comparison. 219 the functional criteria for evaluating shielding concrete encompass a number of attributes, but most of them can be 220 evaluated in the binary way: the requirement is fulfilled or not. one of the most important functional features of heavy 221 concrete is its density. usually among the imposed requirements, the density can be used in the assessment of the cost-222 effectiveness of the concrete mixtures. an appropriate dimensionless index may be used for this purpose (brandt and marks 223 1996, kubissa and glinicki 2017). it is named the concrete density index: 1-(-ref)/ref, where  is the bulk density 224 400 450 500 550 600 650 700 750 800 850 1,00 1,02 1,04 1,06 1,08 1,10 1,12 1,14 1,16 c on cr et e pr ic e (e u r /m 3 ) concrete density index magnetite aggregate concrete in literature barite aggregate concrete in literature concrete mixture m concrete mixture ba the functional criteria for evaluating shielding concrete encompass a number of attributes, but most of them can be evaluated in the binary way: the requirement is fulfilled or not. one of the most important functional features of heavy concrete is its density. usually among the imposed requirements, the density can be used in the assessment of the cost-effectiveness of the concrete mixtures. an appropriate dimensionless index may be used for this purpose (brandt and marks 1996, kubissa and glinicki 2017). it is named the concrete density index: 1-(ρ-ρref)/ρref, where ρ is the bulk density according to table 1 and ρref is the reference maximum density (arbitrarily taken as 3600 kg/m3). figure 1 plots the price (in eur/m3) against the density index of the concrete mixes. the copper slag concrete, regardless of the type of heavy-weight aggregate used, is clearly more economical than the concrete of the compositions reported in the literature containing similar coarse aggregates and sand as the fine aggregate. conclusions experimental investigation on radiation shielding concrete with copper slag waste for small precast elements applications has been performed. based on the experimental results, the following conclusions are drawn: _ with the use of copper slag as fine aggregate, it is possible to produce heavy-weight concrete with a wet consistency suitable for manufacturing prefabricated elements with uncomplicated shape. _ concrete with copper slag have lower water absorption and sorptivity than concrete prepared with sand. the measured water absorption 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concrete mixture r-p, the sorptivity were 57.8%, 59.0% and 50.6% lower and the water absorption were 22.5%, 29.6% and 8.8% lower for concrete mixtures m, ba and r-cs, respectively. _ the concrete mixes with barite, magnetite and basalt aggregate are more cost-effective than other heavy-weight concrete compositions reported in the literature. it is evident that at similar concrete density index, concrete mixtures m and ba are more economical with lower prices. 47 journal of sustainable architecture and civil engineering 2018/1/22 can we design concrete to survive nuclear environments? concrete international. 2017; 39(115): 53–59 lim yk. shielding effectiveness of magnetite heavy concrete on cobalt-60 gamma-rays. journal of the korean nuclear society. 1971; 3(2): 65–75 meenakshi sudarvizhi s, ilangovan r. performance of copper slag and ferrous slag as partial replacement of sand in concrete. international journal of civil and structural engineering. 2011; 1(4): 918–927 ouda as. development of high-performance heavy density concrete using different aggregates for gamma-ray shielding. progress in nuclear energy. 2015; 79: 48–55. https://doi.org/10.1016/j.pnucene.2014.11.009 piotrowski t, gryziński ma. ocena efektywności nowej generacji betonów osłonowych przed promieniowaniem jonizującym w oparciu o pomiary we wzorcowych polach promieniowania [effectiveness evaluation of new generation shielding concrete against ionizing radiation based on measurements in standard radiation fields]. czasopismo inżynierii lądowej, środowiska i architektury. 2016; 63(1): 141–148 rzechuła j. gospodarcze wykorzystanie odpadowego ścierniwa z żużla pomiedziowego [economic use of waste abrasive from copper slag]. in: łuszczkiewicz a, ed. fizykochemiczne problemy mineralurgii, zeszyt 28. wrocław: politechnika wrocławska; 1994: 207–218 saferna m, kaszuba s. betony o właściwościach specjalnych [concrete with special properties]. in: v sympozjum naukowo-techniczne “reologia w technologii betonu”. gliwice; 2003: 15–29. about the authors wojciech kubissa assist. professor warsaw university of technology, faculty of civil engineering, mechanics and petrochemistry main research area sustainable development in concrete technology, materials engineering, civil engineering address 17 łukasiewicza st., 09 400 płock, poland tel. +48-242626254 e-mail: wojciech. kubissa@pw.edu.pl roman jaskulski assist. professor warsaw university of technology, faculty of civil engineering, mechanics and petrochemistry main research area thermal properties of concrete, sustainable concrete materials, recycling and re-use of industrial waste in cement composites address 17 łukasiewicza st., 09-400 płock, poland tel. +48-243672182 e-mail: roman. jaskulski@pw.edu.pl pui-lam ng adjunct professor vilnius gediminas technical university, faculty of civil engineering main research area sustainable concrete materials and structures, concrete science and nanotechnology, high-performance cementitious materials address sauletekio al. 11, vilnius lt-10223, lithuania tel. +370-62423921 / +852-95875310 e-mail: irdngpl@gmail. com jiajian chen assoc. professor foshan university, department of civil engineering main research area high-performance concrete, environmentallyfriendly concrete address 18 jiangwan rd, foshan city, guangdong province, china tel. +86-13450891042 e-mail: chenjiajian@ fosu.edu.cn journal of sustainable architecture and civil engineering 2016/3/16 20 introduction *corresponding author: fgiama@auth.gr u-value: a key role parameter for sustainable buildings http://dx.doi.org/10.5755/j01.sace.16.3.15442 effrosyni giama*, elli kyriaki, agis m. papadopoulos process equipment design laboratory, school of mechanical engineering, aristotle university of thessaloniki, building d, 54124, thessaloniki, greece received 2016/07/03 accepted after revision 2016/10/04 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 20-31 doi 10.5755/j01.sace.16.3.15442 © kaunas university of technology u-value: a key role parameter for sustainable buildings jsace 3/16 buildings have a considerable environmental impact that corresponds to almost 30% of the global carbon footprint, with a prediction for further growth, and to 40% of the final energy consumption in the eu. the eu therefore has set a goal to reduce primary energy use by 20% by 2020, which is one of the five headline targets of the european 2020 strategy. moreover, the european commission has established since 2002 a common policy for sustainable buildings and low environmental impact materials promoting energy efficiency and reduction of greenhouse gases (ghgs), based on a series of directives and regulations. a key role parameter for sustainable building construction is the appropriate building envelope’s thermal insulation in order to reduce its thermal losses. this was firstly introduced in greece with the regulation of building insulation in 1979. therefore, the paper focuses on the implementation of thermal insulation at buildings in compliance with the greek national legislation framework during the last forty years. in this line of approach, measurements of the u-values and of the internal and external surface temperatures were carried out, in residential and office buildings. the sample consisted of buildings with construction dates that mirrored the development in legislation and in the building practice. keywords: energy efficiency, sustainable building, thermal insulation, u-value it is well known and documented that the building sector is responsible for the 40% of the total final energy consumed in the eu. specifically, the residential sector was responsible for the 27% of the total final energy consumption in 2010, while the tertiary sector was responsible for the 16% respectively. therefore, the european parliament approved the energy performance of buildings directive (epbd) 2002/91/ec and the recast directive 2010/31/ec. except from those directives, the eu set the main goals for energy, transport and ghg emissions not only for 2020, but also for the following decades; 2030 and 2050. the main goal is no other than the gradual reduction of the energy consumption and ghg emissions (eea 2015, antoniadou et. al. 2015). on a global scale, building sector accounts for the 32% (118,6 ej) of final energy consumption for 2012 and 53% of global electricity consumption. according to the international energy agency (iea), final energy consumption in building sector was increased by 1,5% every year, in 2000-2012. it is estimated that building’s energy consumption will continue to have an increasing trend with a high rate (annually 1,4%), reaching 142,7 ej (iea 2015, santamouris et. al. 2015) buildings can be divided in to two main categories: a) residential buildings and b) non-residential buildings. in europe, 75% of building stock are residential buildings and only 25% are non-residen21 journal of sustainable architecture and civil engineering 2016/3/16 tial. more particularly, in greece residential buildings can be divided in to two main subcategories: a) single-family houses and b) multi-family houses, as it is shown in fig. 1. the common goal is the reduction of energy consumption in buildings at least up to 20% and in fig. 1. distribution of building sector in europe and greece the common goal is the reduction of energy consumption in buildings at least up to 20% and in order to achieve this target, effective interventions in existing buildings are required. this need of improvement was initially expressed by means of the directive 2002/91/ec for the energy performance of buildings and its review (2010/31/ec). these directives have been harmonized in greek legislation with the following laws and ministerial decisions (md): (i) law 3661/2008, (ii) md 2008 for public buildings, (iii) law 4122/2013 for under construction, respectively. despite the fact that the greek law 4122/2013 has been published recently, the construction of the buildings is still following the demands of the previous regulation (greek law 3661/2008). kenak (the regulation on the energy performance of buildings) along with totee (the technical guidelines of the technical chamber of greece) are leading in changing the way in building envelope upgrades (antoniadou et.al. 2014, eurima 2011). in case of greece and according to hellenic statistical authority (figure 2), 41% of the existing building stock was constructed before 1970 under no regulation concerning insulation. also, approximately 35% of the buildings were constructed in 1980-2010 under the 1st thermal insulation regulation of greece and only a small number of buildings (7%) were constructed after 2010 and are in accordance to the kenak regulation (hellenic statistical authority 2015, theodoridou et. al. 2011). fig. 2. development of construction rate in greece in accordance to hellenic statistical authority fig. 1 distribution of building sector in europe and greece order to achieve this target, effective interventions in existing buildings are required. this need of improvement was initially expressed by means of the directive 2002/91/ec for the energy performance of buildings and its review (2010/31/ec). these directives have been harmonized in greek legislation with the following laws and ministerial decisions (md): (i) law 3661/2008, (ii) md 2008 for public buildings, (iii) law 4122/2013 for under construction, respectively. despite the fact that the greek law 4122/2013 has been published recently, the construction of the buildings is still following the demands of the previous regulation (greek law 3661/2008). kenak (the regulation on the energy performance of buildings) along with totee (the technical guidelines of the technical chamber of greece) are leading in changing the way in building envelope upgrades (antoniadou et.al. 2014, eurima 2011). in case of greece and according to hellenic statistical authority (fig. 2), 41% of the existing building stock was constructed before 1970 under no regulation concerning insulation. also, approximately 35% of the buildings were constructed in 1980-2010 under the 1st thermal insulation regulation of greece and only a small number of buildings (7%) were constructed after 2010 and are in accordance to the kenak regulation (hellenic statistical authority 2015, theodoridou et. al. 2011). it is of interest to notice, that the 1st thermal insulation regulation was pretty strict for its time, as it can be seen compared to the respective german regulation in table 1. in fairness it has to be added that the greek regulation relied heavily on the german one, which preceded it by two years. the greek regulation divided the country into three different climatic zones, base on the heating requirement, with different u-value requirements applying for each zone. the values presented in table 1 are for zone b, which is central greece including athens. fig. 2 development of construction rate in greece in accordance to hellenic statistical authority journal of sustainable architecture and civil engineering 2016/3/16 22 the current greek regulation (kenak) which was issued in 2010, divides the country into four different climatic zones, based again on the heating requirements, as expressed by the heating degree days. by comparing the maximum u values of tables 1 and 2, it becomes obvious that kenak has introduced reasonably strict u-value limits, which are in harmony with most contemporary european regulations. furthermore, it is worth mentioning that in accordance to kenak (and of course to the energy performance of buildings directive) all buildings, newly constructed or deeply renovated, public or private, need to obtain an energy performance certification (epc). according to the ministry of reconstruction of production, environment & energy over 590 thousand certifications have been issued in the period of 2011-2014. table 1 the initial regulatory approach of the u values in greece and germany building element maximum u-value [w/m2k] german 1.regulation (1.wsvo 1977) greek 1.regulation* (tir, 1979) walls including openings 1,45 1,90 walls 0,6 0,7 roofs 0,45 0,5 floors to unheated rooms 0,80 1,9 building element maximum u-value [w/m2k] climate zone a b c d roofs 0,50 0,45 0,40 0,35 walls 0,60 0,50 0,45 0,40 pilotis 0,50 0,45 0,40 0,35 floors on the ground or above unheated spaces 1,20 0,90 0,75 0,70 walls in contact with groun or unheated spaces 1,50 1,00 0,80 0,70 windows 3,20 3,00 2,80 2,60 facades 2,20 2,00 1,80 1,80 table 2 current u-value requirements per building element (kenak) the thermal transmittance, which is expressed by the heat transfer coefficient (u-value) is the most important feature, which characterizes the thermal performance of building elements. it expresses the rate of heat transfer through a structure, which can be a single material or a composite building element, divided by the temperature difference across that structure. it is therefore a measure of how much heat is lost through a given thickness of a particular material, including the three major ways in which heat transfer occurs – conductivity, convection and radiation. the units of measurement are w/m²k. three temperature values are needed to calculate u coefficient. these three temperature values are the external and internal surface temperatures as well as the ambient air temperature. methodology and measurements 23 journal of sustainable architecture and civil engineering 2016/3/16 the ambient temperatures, inside and outside the building, play an important role when calculating the u-value of an element. if one imagines the inside surface of a 1 m² section of an external wall of a heated building in a cold climate, heat is flowing into this section by radiation from all parts of the inside the building and by convection from the air inside the building. so, additional thermal resistances should be taken into account associated with inside and outside surfaces of each element. these resistances are referred to as rsi and rso respectively with typical values of 0.12 km²/w and 0.06 km²/w for the internal and external surfaces, respectively (giama and papadopoulos 2012). this is calculated by taking into consideration the reciprocal of the r-value and then adding convection and radiation heat losses, as follows (green teg 2015), within the framework of this paper, measurements of the u-value for the two main vertical building elements, namely brick-walls and concrete elements, were carried out. in total, 52 buildings in thessaloniki, greece, were measured, 26 residential and 26 office buildings. based on the construction year, the buildings studied can be classified as depicted in fig. 3. the measurements were made using the device tm 200 u. u coefficient value is the most important parameter for the evaluation of thermal features of construction elements. to calculate u-value, four conditions must be respected: fig. 3 distribution of measured buildings based on the construction year _ the outside temperature should be low, _ the room should be heated _ the wall should not be exposed to wind and sun _ the temperature difference between outside and inside temperature should be more than 20oc. once these four conditions are respected, the measurement of the three temperatures (ti: inside temperature of the room, te: outside temperature, ts: temperature of the internal surface of the wall) allows to get the u coefficient: the coefficient 0,125 corresponds to the superficial thermal resistance of the air-brush on the internal surface of the wall) (user manual umeter). journal of sustainable architecture and civil engineering 2016/3/16 24 the results carried out from the analysis of the measurements are presented below. the first statistical analysis depicts the relevance of u values in different constructing time periods according to the insulation regulation that prevailed when the buildings, both residential and non-residential ones, were constructed. more specifically, in fig. 4 and fig. 5, are depicted the results for residential and non-residential buildings respectively, constructed before 1979, that is prior to the introduction of the first thermal insulation regulation. it is obvious that u-values in the buildings constructed before 1979, when there was no requirement for thermal insulation, are really high. moreover, it is observed that, reinforced concrete and brick walls have different properties: the brick walls was proved to have increased insulation capability compared to reinforced concrete and as a result brick’s u-value for all cases is lower than reinforced concrete’s. still, given the lack of insulation, the overall difference in not really dramatic. results fig. 4 u-value measured for residential buildings constructed before 1979 fig. 5 u-value measured for office buildings constructed before 1979 25 journal of sustainable architecture and civil engineering 2016/3/16 it is of interest to notice in office buildings, that although the brick elements present lower u-values, those are not that low as one would expect them to be, based on the much better thermal transmissivity value of clay bricks compared to armed concrete. this is mainly due to the fact, that the typical greek office buildings of the 1960s and 1970s had rather thin brick walls, with thicknesses not exceeding 16 cm, thereby results in high u-values. one residential building constructed in 1978, with ubrick=0,66 w/m 2k and uconcrete=2,8 w/m 2k, is worth noting. brick’s u-value, is quite low. this was due the fact that at this construction thermal insulating bricks were used, leading hence to a very good u-value. then, in fig. 6 and in fig. 7, u-values for residential and non-residential buildings constructed in 1980-2009, are depicted. in this period, the greek thermal insulation regulation was in effect, which foresaw maximum u-values of 0,7 w/m2k for climate zone c. from fig. 7 and 8 it becomes clear, as the thermal insulation regulation was not fully implemented. u-values, both for brick and reinforced concrete elements. the u values achieved are definitely imfig. 6 u-value measured for residential buildings constructed in 1980-2009 fig. 7 u-value measured for office buildings constructed in 1980-2009 journal of sustainable architecture and civil engineering 2016/3/16 26 proved compared to those of older buildings. however, in most cases, the u-values measured were quite above the maximum u-values required by the regulation, which indicates that insulation applied was not sufficient. also, especially in office buildings, it was observed that in some cases, whilst brick walls were insulated, the load bearing elements of reinforced concrete were not. so, from fig. 9 and 10 and the u-values revealed for both brick and reinforced concrete elements, it becomes clear that the thermal insulation regulation was not fully implemented. finally, in fig. 9, 10, and 11 are depicted the results for the buildings constructed after 2010. the sample of buildings for this period is small, and this is absolutely representative of the economic recession that troubles greece since 2009. one has to notice, that the number of construction perfig. 8 deviation between umax and real uvalue in residential buildings constructed between 1980 and 2009 fig. 9 u-value measured for residential buildings constructed after 2009 27 journal of sustainable architecture and civil engineering 2016/3/16 mits in 2014 was 13.100, compared to more than 77.400 in 2007 (hellenic statistical authority 2015). after 2010, with the implementation of kenak, thermal insulation requirements became significantly tighter. when looking at the results in fig. 10 and 11 one has be careful, as there u-values measured, which are significantly above the ones foreseen by the regulation. a careful research on those buildings showed that their building permits were issued before 2010, and hence prior to the introduction of kenak. they therefore did not have to comply with the new fig. 10 u-value measured for office buildings constructed after 2010 fig. 11 deviation between umax and real uvalue in office buildings constructed between 1980 and 2010 journal of sustainable architecture and civil engineering 2016/3/16 28 regulation. on the other hand, it is particularly hopeful, that the two residential and three office buildings constructed after 2012, comply fully with the kenak requirements. lastly, the average u-value for the different time periods, is shown in fig. 12, 13 and 14 for residential and non-residential buildings respectively. overall, it is obvious that the thermal insulation of both residential and non-residential buildings’ envelopes improved gradually, complying with the requirements of the regulations, albeit with a certain lag, both in terms of time of implementation and of u-values achieved. the building envelope is also strongly connected with the constructions materials selection. the construction materials should be studied not only based on their technical efficiency and suitability but also according to their environmental impact. based on life cycle analysis methodology dominant construction materials such as concrete, brick, steel and insulation materials such as fig. 12 average u-values for residential buildings fig. 13 average u-values for office buildings 29 journal of sustainable architecture and civil engineering 2016/3/16 fig. 14 deviation between umax and real u-values in contemporary buildings constructed after 2010 stonewool, extruded and expanded polystyrene have been evaluated (bribian et.al., 2011; cabeza et.al., 2014; giama and panadopoulos, 2015; bikas and chastas, 2015). the evaluation results have shown that production procedures as well as the transportation process contribute mainly to air emissions and more specific to co2 production. actually the co2 is the most significant emission as a quantity to all the construction products studied. focusing mainly on insulation materials, the cradle-to-gate environmental evaluation results showed that expanded polystyrene and stonewool have lower contribution to environmental impact categories studied compared to extruded polystyrene and polyurethane foam. the functional unit used to the studies mentioned was for the 1kg of insulation material produced. in case the functional unit is changed to the mass of insulation material needed for insulating 1m2 of surface taking into consideration the thermal resistance r of the building element the results are slightly different. in that case expanded polystyrene, extruded polystyrene and stonewool have lower contribution to environmental impact categories studied compared to polyurethane foam. considering those results, it becomes evident, that there is significant potential for improving the current by reducing the environmental impact of the basic building materials and improve the environmental rating of buildings (garcia et.al., 2015). considering that production is the key process and that the use of energy and raw materials are the main issues to deal with, one cold thin of measures focusing on [20]: _ the use of renewable energy sources for the energy needed at the production process, either on site, like for instance biomass, or off-site, like green electricity _ the end-of-life management of building materials and the calculation of waste flows at the production processes, including the reuse, recovery and recycling potential, _ the upgrading of the industrial infrastructure (refurbishment, improved monitoring and conjournal of sustainable architecture and civil engineering 2016/3/16 30 trol of energy consumption, implementation of energy management systems such as iso 50001), _ reducing the transportation emissions by preferring locally extracted raw materials and also fostering the use of biofuels for the vehicles. finally, reuse and recycling of building materials is essential in order to reduce the embodied energy in buildings; the use of recycled steel and aluminium could lead to savings of more than 50% in building’s embodied energy. an even more drastic step is to promote the reuse of construction materials and gain extra points on the evaluation procedure of green certification schemes. the necessity for improving the buildings’ energy efficiency is expressed by a variety of legislative measures in europe and worldwide. this improvement cannot be considered as an independent phenomenon, but has to be seen in context with the environmental and energy policies that have become part of the european and international agenda. furthermore, this development has strong economic and social consequences, as it affects the comfort and well-being of millions of households. producing a piece of legislation is one thing, implementing it is, sometimes, another. in order to determine this possible difference, a field study was carried out by the process equipment design laboratory at the school of mechanical engineering of the aristotle university of thessaloniki. in this paper the results of measuring the u values in 52 buildings located in thessaloniki, greece, of which 26 residential and 26 office, are presented. the results were grouped based on the construction year of the buildings, in compliance with the national regulations valid in the period of the construction. it was observed that, before 1979, a time where thermal insulation regulations did not exist, buildings were built without insulation resulting in significant heat losses. all buildings had similar thermal transmittance properties. later on, with the implementation of the first greek thermal insulation regulation, things began to improve. in the beginning, it was applied partially, mainly in the masonry, which had the form of the double brick wall with the insulation in the cavity in between. however, the reinforced concrete elements were frequently left uninsulated, especially in office buildings. the fact that the measurements showed the majority of buildings of this period, failed to meet the requirements foreseen by the regulation, came as a confirmation of this practice. still, the measurements also showed that the implementation of the regulations gradually improved. in that sense, it is encouraging to notice that, despite the depressing situation of the greek construction sector, which has suffered a contraction of almost 70% between 2009 and 2016, the tight requirements of the new regulation, introduced in 2010, seems to be achieved in practice. external thermal insulation composite systems have succeeded the double brick wall construction, reducing also thermal bridges, high quality insulation materials are used and quality of craftsmanship has improved by means of training. the fact that the final consumers have become more sensitive to energy efficiency, as oil and gas taxation has been increased by 60% in the same period, is certainly also a factor not to be neglected. conclusions references european environmental agency (eea) (2015), h t t p : / e c . e u ro p a . e u / e n e rg y / e n e rg y 2 0 2 0 / i d e x _ en.htm, last accessed: 10 september 2015. antoniadou p., giama e., papadopoulos a.m. low energy office buildings in greece: potential and perspecives. 46th international hvac&r congress and exhibition, belgrade, 2-4 december 2015. international energy agency (iea), energy technology perspectives 2015 excerpt iea input to the clean energy ministerial, tracking clean energy progress 2015, paris pp 46, 2015. santamouris m., papanikolaou n., livada i., koronakis i., georgakis c., argiriou a., assimakopoulos d.n. on the impact of urban climate on the energy consumption of buildings. solar energy, 70, 216 (2001) 201. antoniadou p., leonidaki k., anastaselos d., karlesi t., chadiarakou s., alexopoulos e., kontos m., santamouris m., papadopoulos a.m. application of innovative composite cool thermal insulating materials for the energy upgrade of buildings during summer and winter. 45th international hvac&r 31 journal of sustainable architecture and civil engineering 2016/3/16 congress and exhibition, belgrade, 3-5 december 2014. eurima, u-values for better energy performance of buildings, annex 1, ecofys (2011). hellenic statistical authority, http://www.statistics.gr/portal/page/portal/esye, last recovery: 18 september 2015 thedoridou i., papadopoulos a.m., hegger m. a typological classification of the greek building stock. energy and buildings, 43(10), 2787 (2011) 2779. giama e., a.m. papadopoulos a.m. sustainable building management: an overview of certification schemes and standards. advances in building energy research, (2012). https:/doi.org/10.1080/17512549.2 012.740905 greenteg u-value measurement, http://www. greenteg.com/heat-flux-sensor-old/u-value-measurement/, last recovery: 20 november 2015. user manual of tm 200 u-meter. hellenic statistical authority, survey of the construction sector, elstat, october 2015 (in greek) and respectively of previous years. cabeza, l.f., rincon, l., vilarino, v., perez, g., castell, a., life cycle assessment (lca) and life cycle energy analysis (lcea) of buildings and the building sector: a review, renewable and sustainable energy reviews, 29 (2014), pp. 394-416. https:/doi. org/10.1016/j.rser.2013.08.037 bribian, i.z., capilla, a.v., uson, a.a., life cycle assessment of building materials: comparative analysis of energy and environmental impacts and evaluation of the eco-efficiency improvement potential, building and environment, 46 (2011), 5, pp. 11331140 giama, e., papadopoulos a.m., assessment tools for the environmental evaluation of concrete, plaster and brick elements production, journal of cleaner production, 99 (2015), pp. 1-1. https:/doi. org/10.1016/j.jclepro.2015.03.006 garcía, d.c.g., soberón, j.m.g., higuera, r.c., sánchez, j.l.a., soberón, m.c.g., soberón, l.a.g., lca as comparative tool for concrete columns and glulam columns, journal of sustainable architecture and civil engineering, (2015), doi: http://dx.doi. org/10.5755/j01.sace.11.2.10291 bikas, d., chastas p., environmental assessment of typical construction solutions in residential buildings in greece, journal of sustainable architecture and civil engineering, (2015), doi: http://dx.doi. org/10.5755/j01.sace.6.1.5949 effrosyni giama laboratory teaching staff, dr. mechanical engineer msc process equipment design laboratory, department of mechanical engineering, aristotle university of thessaloniki address process equipment design laboratory, school of mechanical engineering, aristotle university of thessaloniki, building d, 54124, thessaloniki, greece tel. 0030 2310 996153 e-mail: fgiama@auth.gr about the authors elli kyriaki phd candidate, mechanical engineer process equipment design laboratory, department of mechanical engineering, aristotle university of thessaloniki address process equipment design laboratory, school of mechanical engineering, aristotle university of thessaloniki, building d, 54124, thessaloniki, greece tel. 0030 2310 996087 e-mail: kelli@auth.gr agis m. papadopoulos professor mechanical engineering department, director process equipment design laboratory vice-chairman governing board, open university of cyprus process equipment design laboratory, department of mechanical engineering, aristotle university of thessaloniki address process equipment design laboratory, school of mechanical engineering, aristotle university of thessaloniki, building d, 54124, thessaloniki, greece tel. 0030 2310 996015 e-mail: agis@eng.auth.gr journal of sustainable architecture and civil engineering 2017/3/20 68 *corresponding author: alex.mitxelena@ehu.eus from ecological architecture to biomimicry received 2017/10/17 accepted after revision 2017/11/13 journal of sustainable architecture and civil engineering vol. 3 / no. 20 / 2017 pp. 68-74 doi 10.5755/j01.sace.20.3.19295 © kaunas university of technology from ecological architecture to biomimicry jsace 3/20 http://dx.doi.org/10.5755/j01.sace.20.3.19295 alex mitxelena etxeberria*, enkarni gomez genua ets arquitectura. university of the basque country (upv/ehu) introduction the economical development of industrialized countries is based on consumption of resources and worldwide pollution both unsustainable in the long and in the short term. but this model has entailed global warming, desertification of the planet, etc. being aware of this situation and the need of a rapid response (after the second world war, or even before), environmental movements whose ideals were based on “environmental protection” arose. the question was to keep on growing, living, creating but damaging the environment the least possible. the terms “ecological” and “sustainable” emerged and theories and practices grew up with them. the term ecological, however, does not necessarily mean sustainable. sustainability doesn’t only mean not damaging the environment but the possibility of maintaining the productive model in the long term. in principle, sustainability includes ecology by increasing its meaning. that is, what is not sustainable is not ecological. thus, we could say that ideas of ecology and sustainability are complementary if not synonymous. architecture, indeed, being responsible of much of the consumption of resources and pollutant emissions, cannot be left out of this paradigm. architecture must also be ecological. this is one of the reasons why buildings are cataloged and certified for their degree of sustainability and energy efficiency. it is no longer ethical to turn away from the environment. at the beginning of the 21st century, a new paradigm emerges: biomimicry. this idea tries to go beyond respect for the environment, imitating the techniques and resources that nature itself offers us as solutions to problems. this paper presents the way from the paradigm of ecology to the one of biomimicry applied to architecture, and proposes an architecture based on the principles of natural systems, according to a greater respect not only for the environment but also to favor a new balance between human beings and nature, and also among human beings themselves. keywords: architecture, biomimicry, ecology, natural systems. the relationship of the human being with the surrounding environment is not simple, though, life depends on this relationship. the strategies used by the human being in relation to the environment have been different throughout history, starting from adaptation to domination. to dominate the environment has been an aspiration of the human being whose point of inflection can be placed in the scientific revolution of the 17th century (capra, 1982). understanding the world as a machine supposes a change, and the paradigm of domination of nature takes force in detriment of adaptation, and the exploitation of resources acquires a magnitude that over time and history proves itself unsustainable. in this context, different social movements in the second half of the 20th century position them69 journal of sustainable architecture and civil engineering 2017/3/20 selves in front of the challenge of establishing a relationship with nature beyond the domination and exploitation of resources creating a new framework in which nature becomes an agent, not an object of domination nor a dominant entity. thus emerges movements such as “ecologism” and concepts such as “sustainability”. the organization of ibero-american states and the website of its global action program publish “a renewed commitment to education for sustainability”: “the concept of sustainability emerged in the early 1980s, based on scientific perspectives on the relationship between the environment and society and the publication of several relevant documents, notably the world conservation strategy (iucn , 1980, first global strategy for sustainable development) and the brundtland report (our common future, cmmad, 1988). it arises as a result of analyzes of the world situation, which can be described as a “planetary emergency” (bybee, 1991) and long-term (orr, 2013), as an unsustainable situation, the result of human activities, which seriously threatens the future (and now the present) of humanity. there is even talk of a new geological stage, the anthropocene, a term proposed by nobel laureate paul crutzen to highlight the responsibility of the human species in the profound changes that the planet is suffering (sachs, 2008), linked to what folke (2013) qualifies as “the great acceleration of human activity”, especially since the 1950s, which threatens to exceed the limits of the planet.” the concept of biomimicry, on the other hand, proposes inspiration in nature as a way to improve the design of human creations. biomimicry also implies an ecological commitment, since it understands that nature takes millennia developing models that are sustainable. our intention here is to meditate on the way in which we can apply biomimicry for the definition of a sustainable and ecological architecture. we interpret that there are two ways of approaching the biomimetic. the first is the imitation of the forms and structures of nature in a decontextualized way. designing products with nature-inspired shapes is expected to help optimizing resources and improving outcomes, but this does not mean that they are more environmentally friendly or sustainable. the second way of approaching the biomimetic is inspired by nature globally, in its cycles, in its way of using energy and resources. this will create an architecture that respects cycles and energy and also uses environmentally friendly or sustainable materials. in this paper we want to propose some first ideas that can serve as inspiration to develop this paradigm of biomimetic architecture. we want to propose an architecture that takes into account the principles of natural systems defined by benyus (1997) in a critical, ecological and sustainable way. the proposed methodology consists of the application of the principles of natural systems to architecture and urban planning. this forms the basis of the ideation, the method of work and even the obtained results. the principles of natural system are: methods 1. nature runs on sunlight 2. nature uses only the energy it needs 3. nature fits form to function 4. nature recycles everything 5. nature rewards cooperation 6. nature banks on diversity 7. nature demands local expertise 8. nature curbs excesses from within 9. nature taps the power of limits. the application of some of these principles will be immediate or easily solvable. some other principles, however, will require a deeper reflection and will not find a simple application. journal of sustainable architecture and civil engineering 2017/3/20 70 nature runs on sunlight. the passive solar house proposes the use of sunlight to reduce the costs of heat production for the living spaces. in the same way, it proposes to close or isolate the parts that do not receive solar radiation and are, therefore, parts that lose the interior heat (aia research corporation, 1978). the organic architecture of the early twentieth century proposes another way to “take advantage” of sunlight: in addition to collecting solar radiation, it organizes the house according to the movement of the star. architects like frank lloyd wright or hugo häring explore the idea of the house that is organized according to the route of the sun throughout the day. in the early 1920s, hugo häring began to develop housing according to a fluid and dynamic organization that adapted to the inhabitants’ journeys and the sunlight (blundell jones, 1999). the rooms of these houses are not rectangular, their geometry is defined from the movements and the functional routes. windows and interior spaces are organized to capture the sunlight. in addition, depending on the type of light we get from the sun, different throughout the day, different activities are developed. the architect rudolf schindler (1934) built mid-20th century houses in los angeles with translucent roofs to recreate atmospheres in the rooms and join the interior spaces to the exterior. we could consider as biomimetic architecture a solar house that modifies its space in relation to the sun. the sun, the cosmos and nature have a cyclical and eternal structure. a house illuminated according to solar cycles, making the inhabitant aware of the passage of time, of the seasons, reminding individuals of their belonging to the earth and the cosmos. nature uses only the energy it needs. we propose the approach to this point from the definition of needs, from which can be thought the energy required. that is, we must first know which with the needs and then have an idea of the energy that will need to be used. there are nine fundamental human needs classified by artur manfred max neef (1986): results and discussion 1. subsistence 2. protection 3. affection 4. understanding 5. participation 6. leisure 7. creation 8. identity 9. freedom needs such as subsistence, protection and affection can refer to the most private and intimate space. the design of housing in a conciliatory way offers spaces in which its inhabitants, in addition to satisfying the first two, do so taking into account affection as the axis of coexistence (hayden, 1984). other needs are more related to urban design. for example, leisure and participation. again, the gender perspective in urban design will guide us in the creation of a city in which leisure, housing and work are not separated, quite the contrary, we will look for ways that make possible the coexistence of these uses and allow easy access to citizens. in this way, in addition, will achieve a decrease in energy consumption. the creation of these cities by means of participatory mechanisms will guarantee the satisfaction of the needs of understanding and participation, also creating the framework in which to fulfill creation, identity and freedom. measurement in the form of energy of these needs is certainly complex. however, we can understand that depending on the architecture and the city we build, we will consume more or less energy. cities and architectures will be more energy efficient, if the needs of all the people who inhabit are taken into account. if the projects are defined only for the most influential sectors, those groups that have not been considered will represent a higher energy expenditure. in this way, the overall calculation of energy expenditure will not be reduced. 71 journal of sustainable architecture and civil engineering 2017/3/20 nature fits form to function. the functions can be studied until determining their form, but this work will be conditioned according to the way in which we approach the definition of the problem. the analysis to define the functional kitchen performed in the 1920’s in germany resulted in a laboratory in which food preparation was developed very effectively (muxi, 2015). however, it forgot the social aspect of this daily activity, proposing a kitchen that isolated the person who solved these functions. functions change with individual and social customs. a person does not perform the same tasks in adolescence, when he cares for his children or when he loses mobility in a punctual or permanent way. also new social customs and needs arise. the differentiation of spaces is a feature not as widespread in cultures as we can think. the psychologists almerico and pérez lópez (1998), describe the house “highly differentiated” as that in which each part fulfills a certain function and indicates its extension exclusively to the european and north american cultures. before the specialization of the domestic spaces we know, the medieval houses of our culture consisted of a single multifunctional space. the rooms were not specialized, the space of the home was one and, depending on the furniture used and its layout, different actions were carried out throughout the day and according to the needs of its inhabitants (mitxelena, 2014). the japanese architect sou fujimoto (2008) proposes two antagonistic ways of responding to functional needs. as it describes, the house can be created according to the type “nest” or the type “cave”. the “nest” type is formalized according to the expected needs. therefore, each function has assigned a place. thus, the resulting space is concrete and defined, adjusted to certain functions. the “cave” space, by contrast, materializes before defining the functions to be performed. the proposals presented lead us to reflect on the creation of an architecture that responds in a specific way to specific functions. without a doubt, it will be an architecture that will not be able to adapt to new needs and new users. fujimoto’s “nest space” is limited, since the inhabitant cannot modify his routines, improvise or change his customs. however, in the “cave space” the inhabitant can improvise, can change their customs, adapt the house to their needs, their changes. instead of oppressing functions, the cave is a means of provocation without restrictions. nature recycles everything. nature closes the cycles using debris as nutrients, so the falling leaves of the trees nourish the terrestrial substrate that feeds trees and other plants. the circular economy proposes to observe the cycles of nature to apply them to economic concepts for the sake of greater sustainability. “circular economy is an economic concept that is interrelated with sustainability, and whose objective is to keep the value of products, materials and resources (water, energy, ...) in the economy for as long as possible, and waste generation is minimized. it is about implementing a new economy, circular not linear based on the principle of “closing the life cycle” of products, services, waste, materials, water and energy (economia…, 2017).” bringing this concept to architecture forces us to think of buildings or urban systems that recycle or reuse waste. this can be achieved in two different ways, on the one hand, we can create architecture that will not subsequently generate waste (once demolished for example) and can maximize the reuse of materials, in which case it is important to choose the materials and possibly their disposition; on the other, we can talk about buildings, or urban systems that recycle in the day to day. in this sense we could talk about circular economy systems, or circular cities whose first call for accession was made in paris in december 2015, at the climate summit. circular cities network was generated from them, with the objective of sharing experiences in this field. we must think of an architecture that generates less waste and cities that also program the reuse of waste as energy generators and rethinking their uses. journal of sustainable architecture and civil engineering 2017/3/20 72 reusing can also mean sharing. spaces where objects and goods are shared. it also has to do with collaboration, cooperation and involves not only the reuse or recycling, but the reduction of consumption through sharing. for example, housing that fosters coexistence favors both the reduction and reuse or recycling of resources. nature rewards cooperation. natural systems take care of future generations and reward cooperation, so biomimetic architecture must also be facilitative, conciliatory and reward the mutual help of the people who inhabit it. the spaces of relation must be designed also thinking about the encounter, the interchange and the interaction of the people who inhabit them. like nature, we need spaces in which to care for the community and which prioritize the well-being of people. in this way we will create an architecture thought from our way of life, but without forgetting the context of which we are part. thus, it will be a sustainable architecture, from the point of view of energy and social, and also sustainable over time, properly managed. the cohabitation co-housing model is formed by a community that is cohesive in its understanding of the relationship between private life and common life. it is made up of private dwellings and an important endowment of common services. it is planned and managed by its residents, according to the model they decide, allowing them to define the project according to their specific needs. cohousing facilitates coexistence and cooperation among residents, as well as the centralization of facilities and services, providing social, economic and environmental benefits. nature banks on diversity. modernist architecture took to the extreme the idea of the city as a network of communication and movement. the concepts set forth in the athens charter in 1941 proposed a technical and aseptic approach to the territory. the ideas of functionalism had succeeded in eliminating all other possible interpretations of reality. however, after world war ii, new generations of architects and architects understood that differences in places were a source of information to build environments adapted to the physical and cultural characteristics of each environment. again, applying the gender perspective in urban design will design cities in which different functions coexist, making them more accessible and in which interactivity will create more livable spaces. as described by gea 21 (2007) “the mix of uses is key to the goal of conciliation. the segregated and specialized districts oblige to perform the different functions of life in remote spaces: to reside, to buy, to work, to have fun, etc.” in addition, nature is enriched by accumulation and also cities have been built over time and as a result of accumulation. for this reason, the public space is an example of accumulation and diversity, starting from the architecture that conforms it, to the actions and functions performed in it, as well as the inhabitants that move in it. if in agriculture monoculture has harmful effects on ecosystems, in the spaces we build, monofunctionality also has similar effects. it loses diversity of uses and loses the wealth that only the mixture can create. urbanism appears too often as a discipline separating functions, which does not favor social interaction. monofunctionality thus impoverishes life, cultural diversity and the urban landscape. nature demands local expertise. vernacular architecture is the result of its environment. it is characterized by its excellent features with the most elementary formulas. the discreet tradition of popular architecture has always tended to maintain a profitable and sensible relationship with its immediate natural environment. here, too, the idea of the “sustainable” is perceived. the idea is to adapt to the environment and take from it what it offers to be able to build. the vernacular architecture shows us that in places where there are trees columns are made with their trunks and lintels to be able to open the holes of the doors and to hold the covers. in tropical 73 journal of sustainable architecture and civil engineering 2017/3/20 latitudes, lacustrine or flooded habitats appear palafitos, with enclosures and enclosures of leaves of local plaited plants. where there is stone, it is used to stack and make walls, long before they have learned to carve it. however, where there is only soil and straw, adobes or bricks are made. thus, the design of each construction is adapted to the specific climatic conditions of each place. the heat of north africa is fought by the thermal properties of the adobe. in the tropics, braids and frameworks of lightweight structures allow permanent ventilation. the specific physiognomy of vernacular constructions is the result of an evolution similar to that of natural organisms. by means of the trial-error procedure and with the means provided by the environment, in an evolution of thousands of years the types that have been replicated indefinitely have been polished. although we consider that vernacular architecture is characterized by taking advantage of what is near, and building according to available materials around, we should be cautious in the proposal to continue building in the 21st century as was done in the 17th, or 19th. at least as far as western societies are concerned. we must consider today that this sustainability depends basically also on the magnitude of the use of resources. nature curbs excesses from within. society, and in particular the agents who direct society, regulates architecture. nature benefits the system because it seeks to balance it, but when societies and their leaders generate systems that benefit a few to the detriment of others inequalities increase and balance is lost. when the nature loses the balance it exerts the control from within to recover it. this internal control system is called self-regulation. self-regulated societies would therefore be societies whose internal control leads to greater balance. architecture as a social product depends on the groups in which it is created to be balanced and self-regulated. thus, people, new architectural, neighborhood associations, collectivists, aware of the need for self-regulation, may be self-regulating, balanced in their excesses, in the use of materials and technology. for this, the educational proposals in the centers of architecture have to take into account the social responsibility of the professionals so that the discipline itself is a self-regulating agent. nature taps the power of limits. this last point is intimately linked to the previous one, as we have seen, nature is limited to itself, imposes internal limits that avoid excesses and encourage self-regulation. thus, architecture must be limited to itself, from the same profession. the participation of users is also essential. in addition to internal limits or self-regulation, nature takes advantage of external limits. thus the skin marks the boundary between being and non-being. the human being grows aware of the exterior through the relation with the other. the outer limits also structure. they make reality understandable. thus, the combination of internal and external boundaries is also desirable in architecture and urbanism. the architecture and urban planning that center users, citizens and society as a whole contribute to regulation, structuring and defining the limits of what is built and how it is built. it is understood in this way that the limits are internal, the internal limits are always easier to respect than the external or normative limits, which are basically those that today limit architecture and urban planning. the regulations are necessary to avoid excesses, however an excess of regulations can damage the architecture limiting the proposals and subtracting its creativity and imagination. conclusions to realize architecture that fulfills all the conditions of the principles of the biomimicry is perhaps complicated, nevertheless we can approach to the biomimetic and sustainable architecture. the vernacular architecture, without being biomimetic in itself, is perhaps among the forms of architecture that we know, which most fulfills the conditions of biomimicry. however, it should be adapted to current needs and reality; since the exploitation of nearby resources may not be sustainable today and it may be necessary to think about the use of other types of materials. journal of sustainable architecture and civil engineering 2017/3/20 74 references about the authors many of the stamps used to classify architecture from the point of view of ecology and sustainability are not appropriate from our point of view. biomimetic architecture understood as the imitation of the forms of nature, or the use of natural elements within the architecture is not sustainable either in itself. the paradigm of biomimicry is a recent paradigm; whose development is unequal in the different disciplines to which it is being applied. from our point of view, the possibilities that it offers for the architecture are still to be explored in its totality. there are timid attempts at biomimetic architecture that are still partial. it would be necessary to be able to integrate the idea of biomimicry with ecology and sustainability. aia research corporation for the u.s. dept. of housing and urban development, office of policy development and research in cooperation. regional guidelines for building passive energy conserving homes. washington: the gpo office; 1978. amerigo m., perez lopez, r. ambientes residenciales. in: aragones j. i., amerigo m. psicología ambiental. madrid: pirámide; 1998. benyus j. biomimicry. innovation inspired by nature. new york: harper collins; 1997. blundell jones, p. hugo häring. the organic versus the geometric. stuttgart: axel menges; 1999. capra f. el punto crucial. ciencia, sociedad y cultura naciente. barcelona: ed. integral; 1982. fujimoto s. primitive future. tokyo: inax publishing; 2008. gea 21. viviendas que concilian. la perspectiva de género aplicada a las viviendas de nueva construcción. madrid, concejalía de igualdad y empleo. ayuntamiento de fuenlabrada; 2007. hayden d. redesigning the american dream: the future of housing, work and family life. new york: w. w. norton, 1984. max neef a. m. desarrollo a escala humana: conceptos, aplicaciones y reflexiones. barcelona: icaria editorial; 1986. mitxelena a. la esencia humana de la casa. bilbao: upv/ehu; 2014. muxi z. margarete schütte-lihotzky 1897-2000. un día | una arquitecta. consultado el 9 de julio de 2017. 2015. pawlyn m. biomimicry in architecture. london: riba publishing; 2011. riechmann j. biomímesis. ensayo sobre imitación de la naturaleza. ecosocialismo y autocontención. madrid: catarata; 2006. schindler r.m. space architecture. dune forum, oceans, california; 1934. alex mitxelena etxeberria lecturer and vice dean, quality and teaching innovation university of the basque country, school of architecture, department of architecture main research area architectural design address oñati plaza, 2 20018 donostia – san sebastian, spain tel. +34 943 015482 e-mail: alex.mitxelena@ehu.eus enkarni gómez genua lecturer and vice dean, international relations, mobility and multilingualism university of the basque country, school of architecture, department of applied physics ii main research area architecture and gender address oñati plaza, 2 20018 donostia – san sebastian, spain tel. +34 943 015887 e-mail: enkarni.gomez@ehu.eus 15 journal of sustainable architecture and civil engineering 2016/4/17 *corresponding author: juozas.vaiciunas@ktu.lt analysis of drain water heat exchangers system in wellness center received 2016/09/26 accepted after revision 2016/12/07 journal of sustainable architecture and civil engineering vol. 4 / no. 17 / 2016 pp. 15-23 doi 10.5755/j01.sace.17.4.16294 © kaunas university of technology analysis of drain water heat exchangers system in wellness center jsace 4/17 juozas vaičiūnas*, valdemaras geležiūnas, rokas valančius, andrius jurelionis, tadas ždankus kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania http://dx.doi.org/10.5755/j01.sace.17.4.16294 drain water heat exchangers worldwide are used since the end of the twentieth century. different drain water heat exchangers have been installed in lithuania in last five years. performance of these systems varies depending on the type of energy users, equipment and design of the systems, as well as their maintenance. the aim of this paper was to analyze different types of drain water heat exchangers and operational systems from the perspective of energy saving and temperature effectiveness. one drain water heat exchanger system in lithuania was selected for the analysis. calculation of temperature effectiveness showed that in most cases it is possible to save energy for hot water preparation. keywords: drain water heat exchangers, energy savings, domestic hot water introduction space heating and cooling and domestic hot water supply represent the biggest share of energy in residential buildings (torio and schmidt 2010). in recent years energy efficiency has become one of the indicators of economic development, and the rationalization of its use is the subject of numerous scientific studies (turner and doty 2007, tsioliaridou and bakos 2006, schaumann 2007). around the world, the aim is to minimize the negative impact of energy on the environment. evidence that much of the energy utilized in domestic water heating is wasted to the drainage system by applications such showers, tubs, dishwashers etc. for example, a typical dishwashing machine will heat water to over 80 ºc during its sanitation cycle and subsequently discharge this hot grey water to the drainage system at only marginally lower temperatures. a typical washing machine will heat water to 60 ºc and discharge hot grey water in a similar fashion. a typical shower will involve heating water to over 40 ºc, discharging hot grey water to the drainage system at temperatures of approximately 30–38 ºc depending on ambient temperatures (wong et al. 2010). the problem of saving the energy used to heat recovery from drain water usage has been observed in many countries such as the united kingdom (wong et al. 2010), ireland (boait et al. 2012), spain (hernandez and kenny, 2012), italy (torras et al. 2016), netherlands (cipolla and maglionico, 2014), canada (frijns et al. 2013, leidl and lubitz 2009, picard et al. 2004), australia (hobbi and siddiqui 2009) and brazil (beal et al. 2012), where the effectiveness of the use of different technologies, from residential buildings to urban wastewater, for saving energy was analyzed. studies made in swiss (schmid 2009) showed that 15% of the thermal energy supplied to build journal of sustainable architecture and civil engineering 2016/4/17 16 ings is lost through the sewer system; this value rises up to 30% in well-insulated buildings with low consumption. this leads to the fact that, today, sewers represent the largest source of heat losses in buildings (schmid 2009). in lithuania, despite the fact that the costs incurred in the preparation of water at the right temperature is relatively high, the use in residential buildings of heat recovery from drain water still raises a lot of controversy, and drain water heat exchangers are not generally available for sale. this state of affairs may be due to lack of data on the financial performance of the presented investments, as information on cost-effectiveness of a heat recovery system from drain water discharged from sanitary facilities usually comes from the materials from manufacturers. as a result they are not very believable for potential users. the aim of this paper was to review and analyze different types of drain water heat exchangers, for different types of buildings from the perspective of energy saving and temperature effectiveness as well as to outline the differences of their actual performance. review of drain water heat exchangers technologies used in order to reduce energy consumption for hot water heating include among others heat recovery from drain water. current development of technology makes it possible to recover heat from drain water on every stage of its formation, transport and utilization. in a market is it possible to find various types of waste water heat exchangers (fig 1): vertical (b), horizontal (c) or build into the shower basin (a). there are lots of other types and combinations, but in this paper, only most popular waste water heat exchangers will be reviewed. a) vertical drain water heat exchanger (fig.1. b) with construction of metal pipe inside the waste water pipe, receives heat from grey water that is usually 30-38°c temperature. grey water warms up pipe‘s surface which transmits heat to the cold water (5-8°c), which is circulating in metal pipe. another version of vertical waste water heat exchanger – metal pipe which is wrapped around grey water pipe. the principle is the same: warm grey water flow heats up the surface of the pipe and the heat energy is transmitted to cold water which is circulating in wrapped metal pipe. the slower flow of grey water, the better effectiveness of waste water heat exchanger (beentjes et al. 2014). if these kinds of heat exchangers are being installed in public buildings, for example water parks or wellness centers, there should be installed more than one vertical waste water heat exchanger. in this kind of buildings, usage of hot water is relatively bigger than in simple dwelling house. also, there is usually a group of showers installed instead of only one. nevertheless fig. 1 different types of drain water heat exchangers (marked in yellow) a b c 17 journal of sustainable architecture and civil engineering 2016/4/17 methods of analysis choosing this kind of system, the height of storey must be estimated. also it must be placed in the lowest point of the building, mostly in the basement. leidl and lubitz, 2009, picard et al,. 2004 describe example of this kind of heat exchangers. b) waste water heat exchanger build into the shower basin. this flat exchanger is located under the perforated plate constituting the bottom of the basin. the principle of this kind of system is similar to vertical heat exchangers. the heat is transferred through pipe‘s and tray‘s surfaces without using any equipment that requires electricity. furthermore, there is few ways how these systems can be installed and connected to building‘s hot water systems. first, heated water line after waste water heat exchanger is connected to shower‘s water mixer as cold water line. also it is being connected to hot water heating tank, as cold water line too. in this case, water heater receives already warm water, so it uses relatively less energy to heat water. besides, shower tap receives hot water from heater and warm water after heat exchanger, so it uses less hot water to mix a comfortable temperature water (coopermann et al. 2011). c) horizontal type of waste water heat exchanger are more sustainable for public buildings, where hot water usage is relatively high. it uses circulation pumps, storage tanks, rinse machines and other equipment that requires electricity. in this paper, this kind of system will be analyzed. in this type of system, warm water after waste water heat exchanger, accumulates energy in storage tank. cold water after circulating through storage tank heats up and is being used in showers taps as cold water line. also, there is possibility to connect water line after storage tank to water heater too. horizontal type of waste water heat exchanger which was installed in sports and wellness center of anykščiai city was analyzed in this paper work. there are not much this kind of type waste water heat exchangers installed in lithuania. also, none research was made about their effectiveness. on purpose to examine the waste water heat exchanger system in the sports and wellness center of anykščiai city and its effectiveness, this study has been made. 25 meters long, 6 tracks swimming pool, jacuzzi, sauna, hydro massage baths were installed in the sports and wellness center of anykščiai. this center organizes sports events, training and health treatments every day from 8 am to 9 pm. random week was selected for this research and each day the number of visitors was recorded. from 100 to 270 visitors were recorded every day and in general there was 1350 visitors per week. fig. 2 shows specific data of visitors every day in a week. it has been observed that the most visitors were recorded at monday, wednesday, saturday and sunday. fig. 2 „graph of number of visitors in a week“ 197 129 211 159 166 223 252 0 50 100 150 200 250 300 4 5 6 7 8 9 10 n um be r o f v is ito rs 2016, april s5 and s6 s1 s3 and s4 s2 em1 hm1 wm1 journal of sustainable architecture and civil engineering 2016/4/17 18 facility equipped with 8 washbasins and 20 showers. warm waste water from these appliances are draining through separate pipe which is connected to two waste water heat exchangers (fercher type awt-928) that are connected in series. after heat transfer, cold waste water is being drained to towns sewer networks (fig. 3). after heat is collected, in a separate circuit, circulation pump transfers it to 1490 liters storage tank (fig. 3, mark s1). in another circuit cold water (8 ºc) passes storage tank, warms up (approx. to 20 ºc) and then passes washbasins and showers mixing valves where it is being mixed up with hot water circuit (55 ºc). circulation pumps (fig. 3, mark s3, s4) are connected to control box, which is configured to turn on circulation pumps only when the difference between the temperature of warm waste water and water in storage pumps is no lower than 3 ºc. also, this waste water heat exchangers system uses 150 liters water tankage (fig. 3, mark s2) to rinse inside of the heat exchangers of purpose to increase their effectiveness. domestic water that comes into heating system are registered in cold water meter (fig. 3, mark wm1). to register amount of heat being collected in this system, heat meter has been installed (fig. 3, mark hm1). electricity meter (fig. 3, mark em1) collects data about electricity use by circulation pumps. the whole waste water heat exchangers system scheme is shown in fig. 4. fig. 3 waste water heat exchangers system installed in sport and wellness center of anykščiai city 197 129 211 159 166 223 252 0 50 100 150 200 250 300 4 5 6 7 8 9 10 n um be r o f v is ito rs 2016, april 197 129 211 159 166 223 252 0 50 100 150 200 250 300 4 5 6 7 8 9 10 n um be r o f v is ito rs 2016, april s1 a wmi 197 129 211 159 166 223 252 0 50 100 150 200 250 300 4 5 6 7 8 9 10 n um be r o f v is ito rs 2016, april s2 em1 hm1 s3 and s4 s5 and s6 fig. 4 schematic representation of the analyzed unit. t1....t12– temperature sensors; s1– storage tank; s2 rinse tankage; s3, s4 circulation pumps; s5, s6waste water heat exchangers “ b c 19 journal of sustainable architecture and civil engineering 2016/4/17 to measure temperatures at different points, 12 temperature sensors (pt 1000) were installed. measured values were registered to recorder (lumel kd7) every day by every minute. results and discussions fig. 5 graph of all temperature sensors data from one week t1 – temp. sensor before first heat exchanger; t2 – temp. sensor before second heat exchanger; t3 – temp. sensor after first heat exchanger; t4 – cold water temp. sensor; t5 – warmed water temp. sensor; t6 – temp. sensor at the bottom of the storage tank; t7 – temp. sensor at the top of the storage tank; t8 – temp. sensor before both heat exchangers; t9 – temp. sensor after both heat exchangers; t10 – temp. sensor of incoming waste water; t11 – temp. sensor of waste water after first heat exchanger; t12 – temp. sensor of waste water after second heat exchanger.“ all measured points were evaluated for purpose to calculate the effectiveness of waste water heat exchangers by themselves and as the whole system. this research showed that temperatures were changing depending on the number of visitors in the sports and wellness center (see. fig. 5). when the number of visitors increases, the demand of hot water increases too. once the hot water is being used, the warm waste water (up to 32ºc) starts to drain into waste water heat exchangers (temp. sensor t10, t11, t12). then heat is being transferred to cold water through the wall of heat exchanger (temp. sensor t3, t9). after that, heated water (up to 24 ºc) runs to storage tank and is being mixed up with the total water content. after water temperature drops to 20 ºc it runs back to waste water heat exchangers again (t1, t2), and the cycle is repeated again. fig. 5 shows that water that is coming into storage tank and goes out, temperature difference is only few degrees. this is because of the size of storage tank. graph shows that the highest difference is between temperatures of incoming waste water and cold water. the incoming cold water temperature (8ºc) reacted differently. that is obvious because when the usage of hot water decreases or no one is using it, the cold water stays in the pipe. because of the inside temperature of the room where the systems is installed, cold water warms up by the long time period. that’s why sensor t4 shows us the increase of cold water temperature at night time, when sports and wellness center is not working. in purpose to examine the effectiveness of waste water heat exchangers by their own and as the whole system, two graphs (fig. 7 and fig. 6) were made from the fig. 5. temperatures that helps journal of sustainable architecture and civil engineering 2016/4/17 20 to examine the effectiveness of waste water heat exchangers as the system is shown fig. 6. temperatures that helps to examine the effectiveness of waste water heat exchangers by their own is shown in fig. 7. fig. 6 graph of temperature sensors t4, t5, t10 from the data of one week. t4 cold water temp. sensor; t5 warmed water temp. sensor; t10 temp. sensor of incoming waste water fig. 7 graph of temperature sensors t3, t8, t10 from the data of one week. t3 temp. sensor after first heat exchanger; t8 temp. sensor before both heat exchangers; t10 temp. sensor of incoming waste water the temperature effectiveness of waste water heat exchanger: where: tc,o – temperature of coolant in outlet of waste water heat exchanger, °c; (1) tc,i temperature of coolant in inlet of waste water heat exchanger, °c; th,i – temperature of waste water inlet of waste water heat exchanger, °c; firstly, the effectiveness of waste water heat exchanger by himself was calculated. the average temperature of sensors before and after heat exchanger (t8, t3) and incoming waste water sensor (t10) were evaluated. it was found, that the effectiveness decreases when the number of visitors increases. there are 21 journal of sustainable architecture and civil engineering 2016/4/17 exceptions when effectiveness increases and the number of visitors increases too. it is assumed that it can be explained by the unknown behavior of the visitors. average every day’s effectiveness of waste water heat exchanger reliance to number of visitors is shown in fig. 8. research showed that every day’s average temperature (t10) of incoming waste water fig. 8 graph of effectiveness of waste water heat exchanger reliance to number of visitors fig. 9 „ graph of incoming waste water temperatures reliance to number of visitors“ fig. 10 graph of the effectiveness of the whole waste water heat exchangers system reliance to the number of visitors“ 42.2 50.4 35.5 35.2 45.1 34.3 32.2 y = -0.0882x + 56.122 25 30 35 40 45 50 55 120 140 160 180 200 220 240 260 e ff ec tiv en es s of w as te w at er h ea t ex ch an ge rs , % number of visitors 26.8 25.9 26.4 27.7 27.1 28.2 28.6y = 0.0192x + 23.578 25.5 26 26.5 27 27.5 28 28.5 29 120 140 160 180 200 220 240 260 te m pe ra tu re o f w as te w at er , ° c number of visitors 69.5 69.5 62.9 63.2 66.8 62.8 59.8 y = -0.0687x + 78.043 58 60 62 64 66 68 70 120 140 160 180 200 220 240 260 ef fe ct iv en es s of th e w as te w at er h ea t ex ch an ge rs s ys te m , % number of visitors related to the number of visitors (fig. 9). the better attendance the higher average waste water temperature has been observed. this shows that at a greater number of visitors, higher flow rates of waste water drains through heat exchangers and then the waste water heat exchangers exchange less heat to the storage tank. moreover, the effectiveness of the whole waste water heat exchangers system was evaluated. for this kind of analysis, temperatures from sensors that are before (t4) and after (t5) storage tank and at the incoming waste water pipe (t10) was collected. graph of the effectiveness of the whole waste water heat exchangers system reliance to the number of visitors are shown in fig. 10. the results of this experiment shows that the temperature effectiveness of the whole waste water heat exchangers system (59,869,5%) is higher than temperature effectiveness of the separate waste water heat exchangers (32,2-50,4%). journal of sustainable architecture and civil engineering 2016/4/17 22 when the temperature of heated water in the waste water heat exchangers system was recorded, the savings of energy were calculated. the energy that is required to heat cold water (23ºc) from waste water heat exchangers system is 61,96 kwh. energy that is required to heat cold water (8ºc) from waste water heat exchangers systems is 116,79 kwh. this shows that waste water heat exchangers helps to save up to 53% of energy that’s required to heat water. temperature sensors were installed in the waste water heat exchanger system at the wellness and sport center of anykščiai city. the data from the sensors were collected. after the evaluation of the results it was determined that: conclusions 1 the temperature effectiveness of waste water heat exchangers ranges from 32,2% to 50,4%. 2 the temperature effectiveness of waste water heat exchangers system ranges from 59,8% to 69,5%. 3 in both ways, the effectiveness lowers when the number of visitors increases. 4 installing this kind of waste water heat exchangers system helps to save up to 53% of energy that is required to heat water. the authors express sincere gratitude for public institution „sveikatos oazė“ for possibility to analyse the drain water heat recovery system in anykščiai town swimming pool.acknowledgment beal c.d., bertone e., stewart r.a., evaluating the energy and carbon reductions resulting from resource-efficient household stock, energy and buildings55 (2012) 422–432. https://doi.org/10.1016/j.enbuild.2012.08.004 beentjes i, manoucheehri r., collins m.r., an investigation of drain-side wetting on the performance 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https://doi.org/10.1016/j.enconman.2012.08.023 hernandez p., kenny p., net energy analysis of domestic solar water heating installations in operation, renewable and sustainable energy reviews 16(2012) 170–177. https://doi.org/10.1016/j.rser.2011.07.144 hobbi a., siddiqui k., optimal design of a forced circulation solar water heating system for a residential unit in cold climate using trnsys, solar energy 83(2009) 700–714. https://doi.org/10.1016/j.solener.2008.10.018 leidl c.m., lubitz w.d., comparing domestic water heating technologies, technology in society 31 (2009) 244–256. https://doi.org/10.1016/j.techsoc.2009.06.005 naspolini h.f., militão h.s.g., rüther r., the role and benefits of solar water heating in the energy demands of low-income dwellings in brazil, energy con-version and management 51 (2010) 2835–2845. https://doi.org/10.1016/j.enconman.2010.06.021 picard d., delisle v., bernier m., kummert m., on the combined effect of waste-water heat recovery and solar domestic hot water heating, in: proceedings: canadian solar buildings conference, montreal, august, 2004. pilavachi p.a., european union initiatives to promote energy efficiency in the process industries, 23 journal of sustainable architecture and civil engineering 2016/4/17 revue generale de thermique 37 (1998) 159–164. https://doi.org/10.1016/s0035-3159(97)83646-x schaumann g., the efficiency of the rational use of energy, applied energy 84(2007) 719–728. https://doi.org/10.1016/j.apenergy.2007.01.004 schmid f., sewage water: interesting heat source for heat pumps and chillers, energy-engineer fh, swiss energy agency for infrastructure plants, zürich, switzerland, 2009. torio h., schmidt d., development of system concepts for improving the performance of a waste heat district heating network with energy analysis, energy and buildings 42 (10) (2010) 1601–1609. https://doi.org/10.1016/j.enbuild.2010.04.002 torras s., oliet c., rigola j., oliva a. drain water heat recovery storage-type unit for residential housing. applied thermal engineering 103 (2016) 670–683 https://doi.org/10.1016/j.applthermaleng.2016.04.086 tsioliaridou e., bakos g.c., a new methodology for renewable and rational useof energy policy in buildings sector: case study for the island of crete, energy and buildings 38 (2006) 196–206. https://doi.org/10.1016/j.enbuild.2005.06.003 turner w.c., doty s., energy management handbook, the fairmont press inc., lilburn, 2007. wong l.t., mui k.w., guan y., shower water heat recovery in high rise residential buildings of hong kong, applied energy 87 (2010) 703–709. https://doi.org/10.1016/j.apenergy.2009.08.008 juozas vaičiūnas lecturer kaunas university of technology, department of building energy systems main research area water supply and disposal systems, hydronic performance of hvac systems, structural stability of buildings address studentu st. 48-439, lt-51367 kaunas, lithuania tel. +37061556760 e-mail: juozas.vaiciunas@ktu.lt valdemaras geležiūnas master’s student kaunas university of technology, department of building energy systems main research area water supply and disposal systems, hydronic performance of hvac systems address studentu st. 48, lt-51367 kaunas, lithuania e-mail: valdemarasge@gmail.com rokas valančius lecturer kaunas university of technology, department of building energy systems main research area indoor climate, energy savings, renewable energy address studentu st. 48, lt-51367 kaunas, lithuania tel. +37068010000 e-mail: rokas.valancius@ktu.lt andrius jurelionis professor kaunas university of technology, department of building energy systems main research area indoor climate, hvac technologies, energy performance in buildings, renewable energy address studentu st. 48, lt-51367 kaunas, lithuania tel. +37068391004 e-mail: andrius.jurelionis@ktu.lt tadas ždankus professor kaunas university of technology, department of building energy systems main research area fluid mechanics, hvac technologies, energy performance in buildings, renewable energy address studentu st. 48, lt-51367 kaunas, lithuania tel. +37037300492 e-mail: tadas.zdankus@ktu.lt about the authors 39 journal of sustainable architecture and civil engineering 2015/4/13 corresponding author: ayse.muge.oz@ogr.msgsu.edu.tr improving occupant’s satisfaction and productivity in sustainable building design received 2015/07/03 accepted after revision 2015/08/29 journal of sustainable architecture and civil engineering vol. 4 / no. 13 / 2015 pp. 39-48 doi 10.5755/j01.sace.13.4.13048 © kaunas university of technology improving occupant’s satisfaction and productivity in sustainable building design jsace 4/13 http://dx.doi.org/10.5755/j01.sace.13.4.13048 introduction ayşe müge öz , sema ergönül mimar sinan fine arts university, faculty of architecture, i̇stanbul, turkey indoor environmental quality in green buildings is generally assumed to be superior to conventional buildings. this assumption stems from prerequisites in indoor environmental quality credits in leed, breeam and other green building certificates. but the viewpoint of green building occupants on this subject is also needed. quality in lighting, air, acoustics, thermal environment and other environmental aspects must be in accordance with competences for the green building certifications, furthermore they must be in accordance with occupant expectations from an indoor environment. green buildings must provide a productive workplace for its occupants and that is not possible without occupant’s satisfaction and comfort. this paper presents the findings of the literature research about occupant satisfaction, health and productivity in green buildings-particularly in offices and the results of the survey which is administered in a leed ebom (existing buildings operation &maintenance) certified office building in istanbul. two questionnaires are carried out within the context of the study; one is before and the other is after the renovations done so as to get the leed certificate. the study shows that having a leed certificate doesn’t guarantee the maximum employee satisfaction. analysis of the research findings indicate that, green buildings must be designed, renovated and operated considering not only energy and material regulations but also indoor environmental issues that the occupants could face. keywords: indoor environmental quality, satisfaction, leed, office buildings, health. while sustainability becomes more and more important for energy and material usages, it also becomes a key word for organizations. indoor environmental quality and individual performance, health, comfort and overall satisfaction are key factors to determine overall organizational success. current green building practices generally tend to undervalue user factor and they miss the opportunity to use building as a strategic asset (heerwagen, 2000). rating systems like leed or bream rewards indoor environmental quality (ieq) on designated standards but even though these standards are met, occupant satisfaction of these standards is another research subject for more productive green buildings and more productive organizations. analyzing and embedding occupant satisfaction in green design practices are also valuable for future development and improvement of green buildings (abbaszadeh et.al, 2006). ieq is quite related to sick building syndrome symptoms, respiratory illnesses, sick leave and losses in productivity (seppänen &fisk, 2006).especially in working spaces, improving indoor conjournal of sustainable architecture and civil engineering 2015/4/13 40 ditions and ensuring occupants satisfaction and well-being is essential. today’s work culture is team oriented, hence if one employee is absent or not working at full productivity, then the team is hurt exponentially (miller et al., 2009).improving ieq in workplace increases performance which can be expressed in a directly quantifiable reduction of absenteeism, such as a reduction in the number of employees that leave work too early or take long lunch breaks (roelofsen, 2002). fig.1 presents leed ieq criteria and corresponding health issues. ieq of green buildings is generally assumed to be better than conventional buildings. there are many reasons to make this assumption, including improved ventilation, increased personal control, removed indoor pollutants, more usage of day lighting, task lights, green materials etc. (abbaszadeh et al, 2006). however, literature research gives confounding results about perceived ieq and occupant satisfaction in green buildings compared with conventional buildings. while some of the studies present a strong relationship between green buildings and higher occupant satisfaction, some of them present weak or no relationship at all. for example, newsham et.al (2013) assert that green buildings have superior indoor environmental performance compared with similar conventional buildings in terms of environmental satisfaction, satisfaction with thermal conditions, satisfaction with a view to the outside, aesthetic appearance, less disturbance from hvac noise, workplace image, nighttime sleep quality, mood, physical symptoms, and a reduced number of airborne particulates. therewithal, abbaszadeh et al. (2006) assert that, lighting and acoustics quality is not suffi cient in green buildings as against with air quality and thermal comfort. another study (issa et al., 2011) shows that green schools in toronto off er better lighting, thermal comfort, indoor air quality, heating ventilation and air conditioning of indoor environments but does not indicate any signifi cant diff erence for absenteeism and student performance. miller et al. (2009) performed a study to measure green buildings contribution to productive enfig. 1 leed and ieq (singh et.al, 2010) 41 journal of sustainable architecture and civil engineering 2015/4/13 vironment for workers in comparison with non-green buildings and the outcome is the following; 12% strongly agree that employees are more productive, 42.5% agree that employees are more productive, and 45% indicate no change. considering absenteeism, participants indicated %45 fewer sick days, %45 same as before and %10 more sick days after moving to green building. taking into account only the workers claimed increased productivity and fewer sick days, the result is %4.88 increase in productivity and 2.88 fewer sick days taken on average. paul and taylor (2007) compared green charles sturt university and conventional la trobe university in terms of the occupier comfort and satisfaction; they differed only in perceived temperature. other aspects like noise, ventilation, serenity or aesthetics were rated nearly the same. this equality is attributed to the inoperative cooling system in csu building and it is asserted that the negative effect of the warmer environment at charles state university building must have outweighed any positive effects of air quality. another survey in china (gou et al., 2013) shows that green building users are slightly more satisfied than non-green building users in terms of design, needs, productivity and health but they are not significantly more comfortable with indoor environments. even in winter, air, temperature and noise are less comfortable as against non-green buildings. six-star green educational tyree energy technologies building (tetb) in australia is analyzed by wang and zamri (2013).the results demonstrate that occupants are mostly not happy with their space/room layout quality followed by indoor air quality, acoustic quality, lighting quality and lastly thermal quality. it is also mentioned that there is no significant relationship between study/work performance and overall indoor air quality and overall lighting quality. acoustic quality, thermal quality and room/ space layout are more significant factors that possible to effect study/work performance. current researches on ieq clearly indicate the necessity to develop an occupant-centered green philosophy which is supported with the regulatory actions. a green building must be designed, constructed and operated considering user requests and needs. this paper aims to investigate how a green building improves the occupant’s satisfaction, comfort and productivity and focuses on user satisfaction and expectations from green indoor environments. with identifying dissatisfactory factors and their sources in green building indoors, architects and facility managers can also concentrate on this issues as well as certificate competences. results of the former studies will be supported with a survey in a leed certified office building in i̇stanbul. as far as ieq in green buildings is concerned, parameters like lighting quality, thermal quality, air quality, acoustics quality and cleaning quality must be analyzed in order to understand the occupant’s requests and needs. lighting quality leed certificate rewards indoor lighting quality by access to daylight and outdoor views, controllability and energy performance. however, occupant visual comfort and eye health is up to many other parameters like illuminance and luminance, control of glare, distribution, uniformity and light source color (hwang and kim, 2011). the quality of lighting in a space not only depends on the lighting installation itself, but also on many other nonphotometric factors such as the layout of the furniture, color of the room and furniture surfaces, the occupants and how the space is used (chung and burnett, 2000). hwang and kim (2011) describe a standard lighting environment as: ‘visiblesafe and able to work effectively, has clear working view; and visually comfortablehas a suitable mood for work and able to work happily and comfortably.’ as a sustainable strategy typically used in green buildings, day lighting can be defined as maximum utilization of sunlight and minimum usage of electricity with the use of all-glass curtain walls, skylights, solar connectors and concentrators, and tubular day lighting devices. beside reduction of energy consumption, it increases occupant well-being, comfort and productivity through connecting indoor spaces and outdoors. u.s. green building council (2003) presents some correlation between indoor environmental quality parameters journal of sustainable architecture and civil engineering 2015/4/13 42 the daylight and productive learning environment. for example, two year study in north carolina proves, children attending schools with full-spectrum light are healthier in general and they are 3-4 days less absent than students in conventionally lit classrooms. another study in california proves that, students in classrooms with the most natural light score 20 percent higher on math tests and 26 percent higher on reading tests than students in classrooms with the least amount of day lighting. in another study, store with skylights is observed to have a sales index higher than an equivalent store without skylights (heschong et al., 1999).increase in sales can be expounded as a result of sales person productivity as well as customer psychology. nevertheless, day lighting can also cause some problems in a working place. successful daylight must prevent or reduce glare and thermal discomforts that arise from windows and direct sunlight (sharp et al., 2014). controllability is another important issue for both green certification and occupant satisfaction. according to heerwagen (2000): ‘personal control over ambient conditions is especially important to reduce discomfort coping and to achieve conditions appropriate to personal preferences and task needs.’ lighting controllability is significant because of the diversified tasks that require different lighting conditions in an office environment. task lighting as desk lamps, reading lamps and under-cabinet lights are very useful to adjust lighting conditions according to personal needs. manual controls also provide remarkable energy savings. air quality-ventilation air quality in offices is quite important because of the crowded working spaces. air quality problems like inadequate ventilation, chemical contaminants from indoor and outdoor sources, biological contaminants are major factors to causing sbs (sick building syndrome) symptoms (u.s epa, 1991). causal agents of sbs may be chemical, physical, biological, psychosomatic or the synergistic effects of one or all of these agents (singh, 1996). harmful chemicals and biological agents that indoor air can potentially contain are , carbon dioxide, volatile organic compounds (vocs), molds, various allergens, and infectious agents (u.s. green building council,2003).to avert harmful effects of these, leed certificate prerequisites prohibiting tobacco smoke, using low-emitting materials, controlling indoor chemical & pollutant sources and meeting minimum ventilation and air quality requirements. a few office-based studies indicate asthma and allergy associations with indoor environmental conditions and likely to have significant reductions in asthma and allergy symptoms if the moisture problems are prevented or repaired, indoor smoking was reduced, and dogs and cats are maintained outdoors of the homes of allergic subjects (fisk,2000). besides health problems, inadequate air quality also causes performance decrease in offices. a study indicates that every 10% decrease in the proportion dissatisfied with the air quality below the air quality level causing 70% to be dissatisfied can improve the performance of typing by 1.4%, of addition by 1.1% and of proof-reading by 2.3% (kosonen and tan, 2004) .it is also stated that, productivity loss due in thinking is more severe than productivity loss in typing. wargocki et al. (1999) experimented 30 subjects in different air pollution levels. they performed tasks simulating office work and performed psychological tests. the strongest effect of pollution load was on the performance of text typing, fewer characters were typed and there were more typing errors. following performance decreases were seen respectively in addition, logical reasoning, serial addition and stroop. moreover, subjects exerted less effort because they had more severe headaches that reduced performances. among strategies to improve indoor air quality, natural ventilation is the cheapest and easiest option. as against mechanical ventilation, natural ventilation is energy-efficient, environmentally friendly, and inexpensive and it rarely needs maintenance (spengler and chan, 2000).but in some cases, thermal instabilities and window inadequacies oblige mechanical ventilation. if the building is designed considering natural ventilation in advance, mechanical ventilation is rarely needed and additional energy consumption is averted. 43 journal of sustainable architecture and civil engineering 2015/4/13 thermal quality-temperature thermal quality in offices is closely related to employees comfort and well-being. even frontczak and wargocki (2011) assert, thermal environment is generally considered to be most important factor achieving overall indoor environmental quality. in green buildings, building facade is designed as transparent glass curtain walls to allow daylight and views into building. especially in summer, green building is overheated because of direct sunray. as a result, air conditions are set to cooler value to balance indoor temperature to normal value and it leads to increase in energy consumption. complaints of being too hot or too cold are often associated with headaches, fatigue, and mucosal irritation (hodgson, 2002).thermal quality not only affects health and well-being but also productivity of employees. hedge et al. (2005) conducted a field study in a company with using data loggers placed on the workers desks. they state that ‘keystroke productivity improves as air temperature approaches a predicted thermal comfort zone.’ they also assert that in the warm climate the study conducted, lowering the indoor temperature reduces productivity; on the contrary, increasing the indoor temperature can improve productivity. an important factor affecting employee satisfaction about thermal comfort is control and adjustment of temperature. a web-based survey that center for the built environment (cbe) conducted (abbaszadeh et al., 2006) indicates that 76% of all occupants with a thermostat were satisfied with the temperature in their workspace as compared to 56% satisfaction for those without a thermostat. operable windows contribute to thermal comfort as well. when considering how to improve thermal comfort in existing buildings, strategies should be based around building infiltration, insulation and shading (fma austraila,2012).air conditions are one of the leading energy consumers in buildings and they are generally calibrated to extreme values. in summer, offices are excessively cooled and in winter, they are excessively heated. minimizing air condition usages, or at least calibrating an optimum value considerably reduces energy consumption. it also helps to avoid health problems arising from excessive usage of air conditions. acoustics quality acoustics quality in offices generally refers to silent working environment without any distracting noise factors, while also refers to good transmission of the sound in learning spaces like classrooms or lecture halls. the quality of the sound environment is linked to numerous physical parameters like the physical properties of sound itself and the physical properties of a room (frontczak and wargocki, 2011). acoustics quality of green buildings is generally the least satisfactory aspect among others (hodgson et.al, 2008 abbaszadeh et al., 2006).this general dissatisfaction can derive from low partitions to allow daylight and views into building, or hard ceilings and floors to improve air quality. ventilation system relying on operable windows obliges occupants to open windows and office doors; which lowers acoustics quality as well (newsham et.al, 2013; hodgson et.al, 2008). green offices are generally designed as open offices to have a collaborative, broad and spacious working area but it brings along some acoustic problems like background noises and speech privacy. mak and lui (2011) conducted a survey with 259 office workers to assess environmental factors relation with office productivity. the results show that, most annoying noise sources are conversation, ringing phones and machines, with 11.2%, 8.9% and 7.7%. background noise, closing doors, human activity, and non-specified noise sources inside or outside the office are the other noise sources that annoy the workers, respectively. knirk and knirk (1983) assert that, absorbable material surfaces that govern speech intelligibility, or masking sounds or ‘white noise’ can be used to secure acoustical privacy and to counteract distracting conversation noises. thayer et al. (2010) report a decrease from 62 db. to 58 db. in low-frequency background noises with sound masking after renovation. it also ended up in considerable increase in noise level and sound privacy satisfaction. journal of sustainable architecture and civil engineering 2015/4/13 44 the key factors to provide a comfortable acoustic environment are the selection and application of acoustically absorptive surface finishes especially in classrooms and collaborative learning spaces (boglev, 2008).it’s also necessary in open offices in which many employees work together. cleaning quality cleaning quality implicitly affects air quality because of dust, bad odors, and harmful particles in the air in case of inadequate cleaning. especially in crowded offices which are possible to contain many viruses and microbes, regular cleaning service is substantial. to ease cleaning services, furniture and carpeting must be easy-effaceable, anti-dust and antiallergic. this paper analyses the effects of ieq parameters in green buildings on occupant satisfaction, comfort and productivity. for this reason an office building located in i̇stanbul is selected and occupant satisfaction from indoor environment is analyzed. the office building belongs to a construction group company headquarters which received first leed ebom (existing buildings operation &maintenance) certificate in turkey. building was first constructed in 1980’s and then renovated before application to leed certificate. in the renovation period a couple of improvements performed in building indoors. purchasing policy is changed with selection of sustainable materials and most of the waste materials are recycled. energy performance of the building is measured by ashrae standards and energy consumption is decreased with proper systems. lighting system is replaced with energy efficient fittings, electronic devices are selected from between energy efficient ones and water consumptions are monitored on a weekly basis. partitions between spaces are changed with glass curtain walls to allow more daylight into building. open office layout is changed with cubical open office for increased privacy. natural ventilation is changed with mechanical ventilation to increase indoor air quality. the survey includes the questionnaires with the occupants of office building in istanbul. two webbased questionnaires are carried out within the scope of study; one is before and the other is after the renovations .in the first questionnaire in 2011, the number of participants was 110 and in the second one in 2012, the number of participants was 116. the participants are subjected to the questions at five main categories of ieq as lighting, thermal, acoustics, air and cleaning quality. the change between two questionnaires gives some specific information about the green building contributions to occupant satisfaction, which renovations lead up to. methods table 1 presents the distribution of responses and how the satisfaction is changed between 2011 and 2012 .the results of the questionnaires show that occupant’s satisfaction increases in all parameters after the rehabilitations in the building. most significant increases are in thermal quality with %19, acoustic quality with %18 and air quality with %13, while cleaning quality is with %8. the least remarkable increase is in the lighting quality which will also be analyzed. thermal quality of the building is increased after the renovations. renovations include some sustainable actions like; using light colored roofing material to avoid heat islands, restoring exterior insulation and windows and adjusting the indoor temperature to a proper value. according to the results of the analysis by the company, degree of the heat was more than the ordinary; and it is lowered from 24° to 22°.this adjustment not only increased occupant satisfaction but also enhanced natural gas savings to %25.after the renovations, satisfaction increased from %44 to %63 but is still not sufficient mainly because of the insufficient airstream and crowded and constricted working area. ongoing complaints about thermal quality are being too cold or too hot which can be expounded to personal preferences about ambient temperature. acoustic quality is the next most increased factor after the renovations. acoustic complaints before renovations were mostly because of the open office systems which are underperformer in acoustic privacy. to improve acoustic quality in office spaces, open office system is replaced with cubical open results and discussion 45 journal of sustainable architecture and civil engineering 2015/4/13 table 1 indoor environmental quality survey results of leed certificated construction company headquarters in i̇stanbul th er m al co m fo rt ac o u st ic s co m fo rt lig ht in g co m fo rt in do o r ai r q u al it y cl ea ni ng co m fo rt in st an t o ff ic e th er m al co m fo rt w in te r th er m al c o m fo rt s u m m er t he rm al co m fo rt n o is e le ve l ill u m in at io n le ve l ill u m in at io n ha ra ct er is ti c (g la re , r ef le ct io n, e tc .) o ff ic e ai r q u al it y c le an in g s er vi ce s very satisfied 13 19 12 4 16 17 7 18 quite satisfied 12 11 8 15 24 19 7 14 satisfied 48 47 48 24 56 45 27 68 neutral 8 10 23 10 14 22 12 15 not really satisfied 16 10 11 19 5 7 10 dissatisfied 9 12 8 19 1 4 31 3 very dissatisfied 10 7 5 18 2 22 3 total satisfaction score 218 43 177 41 100 total neutral score 41 10 36 12 15 total dissatisfaction score 88 56 19 63 6 total score 347 109 232 116 121 2012 satisfaction percentage (%) 63 39 76 35 83 2012 neutral percentage (%) 12 9 16 10 12 2012 dissatisfaction percentage (%) 25 51 8 54 5 2011 satisfaction percentage (%) 44 21 74 22 75 2012 neutral percentage (%) 11 9 14 11 11 2012 dissatisfaction percentage (%) 45 70 12 67 14 causes of dissatisfaction i̇n su ff ic ie nt a ir st re am to o ho t to o co ld n oi se o f p eo pl e an d en gi ne s i̇n su ff ic ie nt n at ur al lig ht , i ns uf fic ie nt co nt ro lla bi lit y, di st ra ct in g lig ht c ol or i̇n su ff ic ie nt a ir st re am , fo od s m el l, du st d ir ty r es t r oo m s, pr es en ce o f c ar pe t offices. replaced office furniture also has sound absorber panels in each cubical space to enhance better acoustic privacy. photocopiers were also another source of acoustic complaints; therefore they are moved away from the office area. with these renovations, acoustic satisfaction is increased to %39 from % 21 but still relatively poor based upon open offices and noisy hvac system. lighting quality is also increased between 2011 and 2012. according to the daylight computation before certification, productive lighting fixtures are replaced by old ones. private offices and meetjournal of sustainable architecture and civil engineering 2015/4/13 46 ing rooms are on the building periphery and open offices are in the middle of them. the partitions between private offices and open offices are changed with glass partitions to allow more daylight into building. with these renovations, satisfaction degree is increased to %76 from %74 but still not enough to make use of only natural daylight without artificial lighting in all working spaces. the amount of daylight in the open offices is restricted due to the building’s old style small-sized windows. thereby usage of artificial lights is compulsory. air quality of the building is the least scored as satisfactory by building occupants. despite renovations performed, occupant satisfaction increased only to %35 from %23. mechanical ventilation is allocated instead of natural ventilation because small sized windows were not sufficient for ventilation .this mechanical ventilation consists of conditioning procedures of outdoor air and ventilating it to office indoors. current dissatisfaction of air quality after the renovations can be expounded to crowded and constricted working area. cleaning satisfaction showed increase by %8 from 2011 to 2012. this increase can be attributed to change of the cleaning company. complaints about cleaning were also because of the existence of carpet. between 2011 and 2012, carpet is overhauled and consequently, complaints are reduced. the dust that the carpets spread is also reduced and it also increased air quality satisfaction. the study shows that having a green certificate doesn’t guarantee the maximum employee satisfaction. in the leed ebom certified green buildings, it is possible to face some difficulties for occupant satisfaction because of the reasons like the age of the building and inadequate spaces. in the survey conducted in the leed ebom certified office building in istanbul, occupant responses indicate some indoor environmental design implications: 1 open offices are preferable because of more social and participative nature but they are in-effective at sound privacy and acoustic quality. absence of the walls brings along humming noise of people and office equipment which complicates to concentrate. to avert these kinds of acoustic dissatisfactions, office furniture must have sound absorber panels or they must be made of sound absorber materials. cubical open offices perform much better in sound privacy and acoustics quality, so if the working area is designed as open office, modules can be grouped and separated to have an acoustically qualified workplace. 2 if open offices are placed in the middle of the building storey like the building studied in this study, they do not receive enough natural light and usage of artificial light is required. larger windows are necessary to provide more natural daylight. besides, areas on the building periphery must be separated from open offices with glass partitions instead of brick wall to ensure the sunlight diffusion all over the storey. 3 crowded and constricted workplace affects both thermal and air quality negatively. 4 existence of carpet affects both cleaning and air quality negatively. there are a number of limitations identified in this study. one of them is that only one building is examined within the scope of paper. larger studies, with more buildings and participants would allow for more elaborated evaluation of the occupant’s satisfaction and productivity in sustainable buildings. another limitation of this study is that, there is no evidence of the relationship between ieq in green buildings and occupant performance and health. survey doesn’t include self-assessed productivity questions or objective performance analysis in different indoor environmental conditions. it mostly consists on subjective measures of ieq. even if the survey doesn’t’ include any objective data for occupant performance and health; occupant satisfaction is a considerable fact to ensure and maintain occupant comfort and well-being in a workplace. yet another limitation of the study is the ebom certificate that the building has. company headquarters is a 30 year old building, therefore survey results can differ in a newly constructed green building. 47 journal of sustainable architecture and civil engineering 2015/4/13 the primary goal of this paper is to investigate occupant’s satisfaction and productivity in sustainable buildings, especially in offices. ieq is a key factor to determine occupant’s health, well-being and productivity in a sustainable building. analysis of former studies and survey conducted within the paper shows that, green buildings present a qualified indoor environment but it is not possible to generalize all indoor environmental aspects in green buildings as satisfactory. while air quality is generally satisfactory, acoustic quality is generally unsatisfactory. green design practices mostly concentrate on certification requirements, and this can push some occupant needs into the background. occupant participation into green design and green operation is a key for preventing indoor environmental problems that the occupants could face after having a green certificate. in this way, the green building is healthy and productive building with its healthy and productive occupants inside. green buildings are more than energy efficient structures with renewable materials. they cannot complete their mission without satisfied, healthy and productive occupants. especially in green office buildings, occupant satisfaction from indoor environments also brings organizational success and continuity. sustainable environment is much better with sustainability of human comfort, morale, health and productivity. abbaszadeh s., zagreus l., leher d., huizenga c. occupant satisfaction with indoor environmental quality in green buildings. proceedings of the eighth international conference for healthy buildings 2006: creating a healthy indoor environment for people, lisbon, portugal; 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in a green educational building: a case study. in iccrem 2013@ sconstruction and operation in the context of sustainability (pp. 234-246). asce. wargocki, p., wyon, d. p., baik, y. k., clausen, g., & fanger, p. o. perceived air quality, sick building syndrome (sbs) symptoms and productivity in an office with two different pollution loads. indoor air, 1999; 9(3), 165-179. http://dx.doi. org/10.1111/j.1600-0668.1999.t01-1-00003.x ayşe müge öz position at the organization research assistant at mimar sinan fine arts university architecture faculty main research area construction project management address meclis-i mebusan caddesi no:24 fındıklı beyoğlu/i̇stanbul tel. +90 506 840 84 02 e-mail: ayse.muge.oz@ogr.msgsu.edu.tr sema ergönül position at the organization professor at mimar sinan fine arts university architecture faculty main research area construction project management address meclis-i mebusan caddesi no:24 fındıklı beyoğlu/i̇stanbul tel. +90 532 798 7621 e-mail: sema.ergonul@msgsu.edu.tr about the authors journal of sustainable architecture and civil engineering 2017/2/19 92 *corresponding author: jennifer.keenahan@ucd.ie sustainable design using computational fluid dynamics in the built environment – a case study http://dx.doi.org/10.5755/j01.sace.19.2.17991 jennifer keenahan* arup, 50 ringsend road, ringsend, dublin 4, ireland and university college dublin newstead, belfield, dublin 4 reamonn macreamoinn, cristina paduano arup, 50 ringsend road, ringsend, dublin 4, ireland received 2017/04/19 accepted after revision 2017/05/30 journal of sustainable architecture and civil engineering vol. 2 / no. 19 / 2017 pp. 92-103 doi 10.5755/j01.sace.19.2.17991 © kaunas university of technology sustainable design using computational fluid dynamics in the built environment – a case study jsace 2/19 in recent years, end users have become more concerned with the human experience and the personal comfort of the individual is becoming more important in the design of the built environment. computational fluid dynamics (cfd) is a tool that permits assessment of personal comfort. cfd is a stream of fluid mechanics that utilises numerical methods to analyse and solve problems involving fluid flows. while research applications of cfd are developing, as is the use of cfd in the aerospace and formula1 industries, the use of cfd in civil engineering applications is currently at the cutting edge. this paper will investigate the use of computational fluid dynamics as a complementary approach to wind tunnel testing for pedestrian comfort. the results showcased here were determined through a consultancy project by the team at arup, dublin. on determining potential wind problems, mitigation measures were proposed and tested in cfd to prove that the mitigation measures were effective. these proposed changes were incorporated into the final design and as a result planning permission was awarded for the development. this work is exemplar of how, from the very conception of the project design, new technological advances lead to a better built and sustainable environment for all. keywords: built environment, cfd, pedestrian comfort, wind, wind tunnel test. the design of urban environments ought to focus on the effects of the design on the outdoor built environment, in addition to focusing on the envelope of the building and on the quality of the indoor environment. to date, the outdoor built environment has received relatively little attention by designers, particularly with respect to wind. the negative effects of windy environments were first discussed by wise (1970) who noted the presence of vacant shops where shoppers were discouraged due to the windy environment. separately, lawson and penwarden (1975) noted the deaths of two elderly ladies who were victims of windy gusts near a high-rise building. it is evident that the risks and consequences of unfavorable wind environments for pedestrians cannot be overstated. the main source of pedestrian discomfort is related to the force of the wind felt on their body and their clothing as additional effort is required to negotiate the wind. the beaufort scale was the first empirical measure that related wind speed to observed conditions, it has been presented and incorporated in wind comfort studies by (penwardon, 1973 and soligo et al., 1998). other authors (penwardon et al., 1975 and murakami and deguchi, 1981) propose threshold wind veintroduction 93 journal of sustainable architecture and civil engineering 2017/2/19 locities for pedestrian wind comfort. more detailed comfort criteria reflecting individual opinions on acceptable frequencies of occurrence of various wind speeds have been proposed in isyumov & davenport (1976), apperly and vickery (1974) and melbourne and joubert (1971). later, grades of comfort are introduced related to the probability that a threshold wind speed may be exceeded (willemsen and wisse, 2007). the lawson comfort criteria (lawson and penwarden, 1975; lawson, 2001) quantifies an individual’s annoyance with the wind. it enables the level of pedestrian discomfort to be evaluated based on pedestrian activity, wind speed and frequency of occurrence. a wind is acceptable if it goes unnoticed, unpleasant if it is noticed but it does not prevent the area from being used for its designated purpose, and annoying when it is of sufficient strength and frequency to prevent the area being used for its designated purpose. certain building configurations may give rise to intense local wind flows. buildings that stand taller than their neighbors collect the wind over much of their height and direct it towards the ground. intuitively, given that wind speed increases with height, the taller the building, the faster the wind speeds delivered to ground level (lawson, 2001). the funneling of wind through narrow gaps between buildings can also cause unpleasant wind environments. to move towards a long-term sustainable built environment that is useable by pedestrians, it is necessary to determine the risk and occurrence of possible zones of unacceptably high pedestrian discomfort. it is crucially important that appropriate design decisions are made to eliminate such zones. while the challenge of wind-induced discomfort of pedestrians is not new, more modern types of buildings and open space configurations have evolved to create potentially even windier environments. typically, such configurations involve tall buildings rising well above the surrounding built environment and adjacent to open spaces such as plazas and malls (simiu, 1996). there are many design considerations that architects, engineers and planners take into account to mitigate windy conditions in the built environment. the orientation of commercial and residential buildings, the selection of the type of balcony (winter-garden or re-entrant balcony) relative to the direction of the prevailing winds and the inclusion of wind canopies and shelters are some examples that markedly improve the wind environment for the end users and pedestrians. urban authorities and councils are beginning to recognize the importance of pedestrian wind comfort and wind safety. the dutch wind nuisance standard nen 8100 (nen, 2006), to the best knowledge of the authors, is the first standard in the world to account for pedestrian wind comfort in the built environment. it is noteworthy that the standard unambiguously permits the designer to choose between wind tunnel experimentation and cfd modelling to assess the wind environment (blocken et al. 2012). flachsbart (1932), concluded that simulations of the behavior of wind around buildings should be conducted in wind tunnels. wind tunnel testing is now a long-established approach and the knowledge and experience gained over the years has established wind tunnel testing as the traditional method for conducting wind analysis. however, wind tunnel testing is not without its short-comings. for instance; _ wind tunnels requires physical equipment to collect the data. as a result, it is only possible to monitor the flow field at a limited number of locations and it is difficult to measure the pressure field and velocity field at the same time. furthermore, the presence of the measuring device can often disrupt the flow. _ for a truly representative model, the reynolds number should be similar for the model as for the prototype. however, the reduced scale models used in the analysis of tall or longspan structures would require impossible air flow velocities though the tunnel to ensure reynolds number consistency. _ time and effort is required to develop a scale model for the wind tunnel test, this renders them unsuitable to the earlier stages of the design process when the design is in greater flux. _ wind tunnel estimates from different wind tunnels can vary widely. journal of sustainable architecture and civil engineering 2017/2/19 94 with the advent of computational power and the capability of numerical methods like finite element analysis, it is now possible to accurately simulate wind flow conditions in a virtual environment. computational fluid dynamics (cfd) is an advanced modelling technique that establishes a basis to solve problems of fluid flow. cfd solves partial differential equations in continuum mechanics using numerical techniques. the equations governing fluid motion are based on the fundamental physical principles of the conservation of mass, momentum and energy. cfd discretizes the overall problem into many small volumes that can be solved more easily (ferziger, 2002). combining the solutions from these small volumes permits the generation of a complete solution. cfd has been successfully applied in many areas of fluid mechanics including, heat and mass transfer (lien, 2012), chemical reaction and combustion (senveli, 2014), aerodynamics of cars and aircrafts, and pumps and turbines. applications of cfd to the built environment include wind modelling and the dynamics response of structures (montazeri, 2013) ventilation (meroney, 2009) fire, smoke flow and visibility (senveli, 2014) dispersion of pollutants and effluent (prasad, 2013) and heat transfer in buildings (kobayashi, 2003). traditionally, the interaction of these phenomena has been carried out experimentally, using scaled models and short calculations. computational wind engineering (cwe) is a branch of cfd concerned with the behavior of wind. similar to wind tunnel tests, it can be used to understand the interaction of wind flow through an urban environment and the effect of a proposed development on the local wind microclimate. in cfd the problem is expressed as a mathematical model and is solved iteratively using numerical methods this gives abundant benefits over the physical wind tunnel, including: _ the entire flow field is solved simultaneously in cfd and therefore, it is possible to collect results from anywhere within the computational domain without influencing accuracy. _ the scale of the model is irrelevant in cfd modelling as the computational domain can be set to any scale. as a result, cfd does not suffer from any issues with reynolds number violation. _ generally, cfd software packages interface easily with computer aided-design (cad) packages. should changes in design be necessary, it is relatively easy to adjust a cfd model due to these new design specifications and therefore, cfd is better integrated into iterative design processes. however, cfd is not without its disadvantages. for instance, it is difficult to model free stream turbulence in cfd and it can be challenging to accurately model flow separation and free shear layers. if it is possible to verify and validate a cfd model using wind tunnel testing as a benchmark, there is potential to examine a greater variety of flow configurations due to greater flexibility of cfd. lastly, to capture wind flow phenomena in sufficient detail, large finite volume models are necessary requiring significant processing power. these large models generate a great amount of data, which in turn needs to be stored and analyzed. there have been a few studies that use cfd in the built environment. he and song, (1999) used a les simulation cfd model based on the weakly compressible flow equations to simulate pedestrian fields around an urban area. three case studies are presented showing differing wind effects. cfd is not however used as a design tool to modify proposed buildings nor is a wind tunnel test used to validate the results. a comparison of numerical results is presented with the classic wind tunnel tests on different buildings. janssen, blocken and hooff (2013) compared different wind comfort criteria based on a case study of eindhoven university, netherlands. validation was possible using real-world measurements from the university, taken over a two-hour span. there was no modification proposed during a design process. in (blocken janssen and hooff, 2012) a framework is presented for the 95 journal of sustainable architecture and civil engineering 2017/2/19 integration of the existing best practice guidelines into wind comfort and wind safety studies performed with cfd. the same eindhoven university case study and validation is used to build the framework. fadl and karadelis (2013) undertook cfd simulation for wind comfort and safety at coventry university, in the uk. no validation tests were conducted and no changes to the design were needed. this paper proposes a world first, to validate cfd against wind tunnel tests for the same building while also proposing a change in design to alleviate pedestrian discomfort. the results showcased here were determined through a consultancy project by the team at arup, dublin. on determining potential wind problems, mitigation measures were proposed and tested in cfd to prove that the mitigation measures work. these proposed changes were incorporated into the final design and as a result planning permission was awarded for the development. this work is exemplar of how, from the very conception of the project design, new technological advances lead to a better built and sustainable environment for all. the proposed development at the dublin docklands consists of the construction of an office building ranging in height from 8 to 17 storeys, herein referred to as the dublin docklands tall building. the construction of new buildings and the alteration of the existing landscape may alter the flow of the wind in the surrounding area (penwarden, 1973). it was found that the proposed development can generate a wind environment at ground level that is discomforting or even possibly dangerous to pedestrians, these metrics were determined in accordance with the lawson comfort criteria (lawson, 2001) previously discussed. this case study was first modelled in a wind tunnel test, where the potential for pedestrian discomfort was identified. arup undertook the wind modelling of the entire built landscape using cfd to first validate and prove that the augmentation to the design taking into account these findings. the wind tunnel test and the cfd model are discussed in this section. an assessment of the microclimate was also undertaken to test the cfd model in historic wind conditions. wind tunnel test the objective of a wind tunnel test is to produce estimates of wind effects with specified mean recurrence intervals. wind tunnel tests measure aerodynamic or aero-elastic data associated with wind-structure interaction, i.e. aerodynamic pressures, the dynamic or aero-elastic response and wind speeds affecting pedestrian spaces. the object or model under investigation is placed in the centre of the wind tunnel, sufficiently downstream to facilitate the development of the velocity profile, and sufficiently upstream to capture the wake of the flow. air at a given velocity is blown down the tunnel using a fan. small blocks or spike are used upstream of the model under investigation to simulate turbulence in the flow. sensors are distributed on the surface of the scale model placed in locations of interest. a boundary layer wind tunnel study of the proposed development at the dublin docklands tall building was previously conducted by another company at a local wind tunnel facility to assess the impact of the proposed development on the wind microclimate. the study examined the wind microclimate of the dublin docklands in its existing configuration and the proposed development. cfd modelling methodology modelling in cfd comprises three main stages: pre-processing, simulation and post-processing. pre-processing involves the construction of the geometric model for the flow domain of interest, and the subsequent division of this domain into small control volumes (cells), a process often called ‘meshing’. the flow field and the equations of motion are discretized, and the resulting system of algebraic equations is solved to give values at each node. once the model and methodology journal of sustainable architecture and civil engineering 2017/2/19 96 the mesh have been created, appropriate initial conditions and boundary conditions are applied. the navier-stokes equations, the governing equations for the behaviour of fluid particles, are solved iteratively in each control volume within the computational domain until the solution converges. the field solutions of pressure, velocity, air temperature and other properties can be calculated for each control volume at cell centres and interpolated to out points in order to render the flow field. post-processing involves graphing the results and viewing the predicted flow field in the cfd model at selected locations, surfaces or planes of interest. the navier-stokes equations, used within the cfd analysis, apply a numerical representation to approximate the laws of physics to produce extremely accurate results, providing the scenario modelled is representative of reality. as part of the computational process, the domain was divided into a total of 16 million cells. the fig. 1 computational domain fig. 2 wind speeds – comfort criteria fig. 3 wind speeds – distress criteria cells range in size from 0.4 m at the dublin docklands tall building to 3.2 m at the outer domain (fig. 1). closed boundary conditions were applied on the bottom face of the domain, representing the ground. open boundary conditions were modelled elsewhere. as with any computer simulation, the quality of the results is dependent on the quality of the inputs; the assumptions, modelling characteristics employed and the equations used to represent the phenomena. there will inevitably be approximations, and a robust model validation process is essential. a high-level understanding of the modelling process and of the phenomena being modelled is necessary for the output to be of any practical use. assessment of the climate the local wind climate was determined from historical meteorological data recorded at dublin airport. two different datasets were analysed, namely; the data associated with the maximum daily wind speeds recorded over a 30-year period between 1985 and 2015, and the mean hourly wind speeds recorded over a 10year period between 2005 and 2015. the wind speeds in the vicinity of the development will differ from the wind recorded at dublin airport. it is necessary to transform the wind speeds to take account of local conditions (simiu, 2001). from this, a single wind speed profile was determined for each direction for both comfort and distress criteria, as illustrated in fig. 2 and fig. 3. 97 journal of sustainable architecture and civil engineering 2017/2/19 a verification of the model used in this research investigated the effects of five parameters; the upstream length, the downstream length, the model height, the cross-stream width and mesh size. in essence this captures the sensitivity of the results to the size and shape of the domain. using a modified partial design technique adapted from (box, 2005), nine models were created using variations in these parameters, the combinations of which are shown in table 1. verification by sensitivity analysis table 1 nine combinations for use in the partial design technique model upstream length (m) downstream length (m) height (m) cross-stream width (m) = 150 + = 250 = 35 + = 245 = 78 + = 128 = 170 + = 415 1 2 + + 3 + + 4 + + 5 + + 6 + + 7 + + 8 + + + + 9 200 140 103 293 the results of the nine models were analysed to assess sensitivity of the results of wind velocity to each of the four parameters. fig. 4 shows the sensitivity of the recorded velocity at sensor locations h2, b2, e11 and e9. h2 is placed at the north-east corner of the building, b2 is placed on the north-west corner of the building, and sensors e11 and e9 are located in the undercroft. all sensors are at a height of 1.6m. from each of the sup plots of fig. 4, it is observed that the same trend of sensitivities emerge as the upstream length, downstream length, height and cross-section width are altered. examining fig. 4 verification of results from four sensors placed at grid reference points h2, e11, b2, and e9 journal of sustainable architecture and civil engineering 2017/2/19 98 one of these plots, in the case of sensor location h2, as the upstream length increases, less than a 5% decrease in velocity is observed. it was found that the recorded velocities were also slightly sensitive to changes in downstream length. for sensor location h2 as the downstream length increases, the velocities range from 3.8 m/s to 4.25 m/s respectively. less than a 5% increase is observed in the velocities of this sensor as the domain height increases. in relation to the effect of the cross-stream width on results, the velocities recorded at the twelve locations were found to be insensitive to changes in the cross-steam width. the trend seen in these velocities are replicated for eleven other sensors placed at various locations throughout the model. a tenth verification model was created to assess the sensitivity of velocity results to changes in mesh size. in this model, the domain size matches that of the 9th model, provided in the table 1; however, the mesh size was half as fine (0.2 m as opposed to 0.4 m). even with this increase in granularity the velocities observed by the twelve sensor locations were found to be insensitive to decreasing the mesh size. validation fig. 5 cfd data sampling locations at pedestrian level fig. 6 data sampling locations at pedestrian level of the external company to validate the cfd modelling process the environment was recreated in the wind tunnel analysis predetermined by the external company. for the purposes of validation of the models, the original dublin docklands tall building model was considered. the exterior of the building was considered to be smooth, which is consistent with the wind tunnel tests and therefore, it neglects any influence of the external truss on the flow. the equivalent average hourly gust speed is calculated based on 5% turbulence intensity and a k value of 1.5. the data sampling locations (fig. 5 and 6), have been selected to be as close as possible to the exact sensor locations used in the wind tunnel tests. this study focuses on points 18 to 28 and is confined to comparing, at these locations, the cfd results with the findings of the previous microclimate study. the comfort criteria and distress criteria adopted in this study are consistent with the previous wind assessment carried out by the external company. the validation results of the cfd simulation of the dublin docklands tall building shows good consistency with the original wind tunnel test results. as indicated in fig. 7 and 8, the cfd simulation results suggest that many of the same locations identified using wind tunnel testing suffer from pedestrian discomfort and distress. therefore, the results of the cfd models are considered to be consistent with the original wind tunnel test results. 5 6 99 journal of sustainable architecture and civil engineering 2017/2/19 the assessment of the pedestrian comfort and distress in the pedestrian thoroughfare between the 3arena and the dublin docklands indicates that the main areas of concern are at the southern end. the equivalent wind speeds from the perspective of comfort and distress are 12 m/s and 24 m/s respectively. these speeds arise when high westerly winds cause discomfort and distress between the 3arena and the dublin docklands tall building (fig. 9). midway along the building, the equivalent hourly average gust wind speed from a comfort perspective is 8.3 m/s. at the northern end, the analysis reveals that the wind speeds are insufficient to cause either discomfort or distress. in addition, it is possible that winds from the south and north will be of distress to the public. the equivalent hourly average gust speed is estimated at 15.4 m/s and 16.3 m/s from the north and southwest, respectively. these wind speeds exceed the distress threshold for the public of 15 m/s. fig. 7 wind tunnel tests wind microclimate results summary for original dublin docklands tall building with mitigation measures in future environment fig. 8 cfd simulation wind microclimate results summary for original dublin docklands tall building with mitigation measures in future environment 87 fig. 9 distress criteria, wind from the west, minimum values in blue (0m/s), maximum values in red (20m/s) results journal of sustainable architecture and civil engineering 2017/2/19 100 the assessment of the pedestrian comfort and distress in the passageways between the dublin docklands tall building reveals that the wind conditions might be discomforting and distressing to pedestrian. however, the level of discomfort and distress is related to the wind direction. for instance, while westerly winds with an annual return period may produce conditions unsuitable for undertaking any activity within the undercroft, a slight shift in direction to the south results in an acceptable environment. it would appear that much of the pedestrian discomfort and distress is due to westerly winds. from the perspective of comfort, the equivalent hourly average gust speed in the undercroft passageways range between 10 m/s and 13.9 m/s for westerly winds, which is considered uncomfortable irrespective of the activity being undertaken. the main source of distress is due to westerly winds which range between 15 m/s and 30 m/s along the length of the building. these high wind speeds near ground level are due to the building funnelling high level winds downward. the wind speeds are further increased through the undercroft passageways as the wind is forced through narrower openings underneath the building (fig. 10). although it might be expected that easterly winds might cause similar pedestrian discomfort and distress within the building undercroft, it is apparent from fig. 11 that this is not the case. the wall on the western boundary of dublin port acts to disturb the wind. the bluff nature of the wall causes the flow to separate and the formation of large vortex between the wall and the dublin docklands tall building (fig. 12). the vortex acts to push much of the wind over the dublin docklands tall building. as a consequence, there is less flow passing under the dublin docklands tall building. fig. 12 distress criteria, wind from the east, minimum values in blue (0m/s), maximum values in red (20m/s) fig. 11 distress criteria, wind from the east, minimum values in blue (0m/s), maximum values in red (20m/s) fig. 10 distress criteria, wind from the west, minimum values in blue (0m/s), maximum values in red (20m/s) 101 journal of sustainable architecture and civil engineering 2017/2/19 modifications to the design the assessment of the wind microclimate indicates that westerly winds are responsible for most of the pedestrian discomfort and distress associated with this development. furthermore, the high-speed winds present at ground level are largely due to downdrafts. these high-speed winds are further exacerbated by the narrower openings between the cores within the undercroft. it should be possible to improve the quality of the public realm near the dublin docklands tall building with respect to the wind microclimate by preventing these high-speed air flows in reaching the ground. the downdraft can be mitigated through the provision of a canopy above ground level along the western edge the building. the design was modified to include a 3.0 m canopy. the purpose of this modification is to enable the canopy to act as a wind gutter. the extension of the canopy to the edges of the building helps the development of a positive pressure gradient along the canopy with the objective of driving the flow around the building rather than underneath it. the modifications to the canopy were considered in a further simulation. in addition, while the original cfd models utilised a relatively coarse mesh, which permitted a crude representation of the exterior truss in the model, this model adopted a finer mesh of moderate refinement, which enables the truss structure to be represented more accurately. the results of this simulation reveal that the ground level wind speeds are considerably lower than the earlier simulations beneath the building and along the pedestrian thoroughfare between the 3arena and the dublin docklands tall building. for instance, a significant decrease in wind speed was identified underneath the building near the northern core, where the equivalent hourly average gust speed reduced from 30 m/s to 14.5 m/s. this reduction in wind speed is attributed to the provision of a larger canopy. it is apparent from fig. 13 that the canopy does not confine the flow completely. however, it does indicate the presence of a large wake region below the canopy. this wake region does indicate that the canopy disrupts the downdraft. the overall effect is to reduce the velocity of the flow through the undercroft as illustrated in fig. 14 and 15 with the effect of significantly improving pedestrian comfort to acceptable levels. furthermore, the canopy proposed in the design is 3 m wide which enhances its effectiveness. this will further reduce the wind speeds within the undercroft and improve pedestrian comfort to more acceptable levels. fig. 13 comparison of 1.5 m canopy (left) and 2.5 m wind gutter (right) for distress criteria, wind from west, elevation view from the west, minimum values in blue (0m/s), maximum values in red (20m/s) journal of sustainable architecture and civil engineering 2017/2/19 102 this research has validated that cfd obtains equivalent results, comparable to and in agreement with a wind tunnel test. further, as potential wind problems were uncovered in the design stage of a building submitting for planning permission, mitigation measures were proposed and tested in cfd to verify the proposed changes. these changes were incorporated into the final design and as a result planning permission was awarded for the development. this case study is exemplar of how, from the very conception of the project design, new technological advances lead to a better built and sustainable environment for all. this paper shows that cfd has a role to play in informing design to mitigate unpleasant wind conditions. in summary, cfd is a strand of applied research that has the potential to improve quality of design, is of immediate practical use and has a significant role to play in sustainable consulting engineering. fig. 14 distress criteria, wind from west, elevation view from the west, minimum values in blue (0m/s), maximum values in red (20m/s) fig. 15 distresscriteria, wind from west, elevation view from the north, minimum values in blue (0m/s), maximum values in red (20m/s) 14 15 conclusions acknowledgment the authors wish to acknowledge the support of arup ireland in the completion of this work. apperly, l.w. and vickery, b.j. the prediction and evaluation of the ground level wind environment. in proceedings of the fifth australasian conference of hydraulics and fluid mechanics, university of canterbury, christchurch, new zealand, 1974. blocken, b., janssen, w.d., van hooff, t. cfd simulation for pedestrian wind comfort and wind safety in urban areas: general decision framework and case study for the eindhoven university campus. environmental modelling and software, 2012; 30: 15-34. https://doi.org/10.1016/j.envsoft.2011.11.009 box, g. e.; hunter, w. g.; hunter, j. s. (2005). statistics for experimenters: design, innovation, and discovery (2nd ed.). wiley. isbn 0-471-71813-0. fadl, m.s. and karadelis, j. cfd simulation for wind comfort and safety in urban area: a case study of coventry university central campus. international journal of architecture, engineer and construction, 2013; 2(2): 131-143. https://doi.org/10.7492/ijaec.2013.013 ferziger j.h. and peric m. computational methods for fluid dynamics. 3rd ed. springer; 2002. https:// doi.org/10.1007/978-3-642-56026-2 fachsbart, o. wind pressure on closed and open buildings. the results of the aerodynamic experiment at gottingen, l. prandtl and a. betz (eds.), publisher of r. oldenbourg, munich and berlin, 1932. he, j. and song, c.s.c. evaluation of pedestrian winds in urban area by numerical approach. journal of wind engineering and industrial aerodynamics, 1999; 81: 295-309. https://doi.org/10.1016/s0167-6105(99)00025-2 isyumov, n. and davenport, d.g. the ground level wind environment in built-up areas. in proceedings of the fourth international conference on wind effects on buildings and structures, london, 1975, cambridge university press, pp. 403-422. janssen, w.d., blocken, b., and van hooff, t. pedestrian wind comfort around buildings: comparison of wind comfort criteria based on whole-flow field data for a complex case study. building and environment, 2013; 59 547-562. https://doi.org/10.1016/j. buildenv.2012.10.012 kobayashi, n. and chen, q. floor-supply displacement ventilation in a small office. indoor and built references 103 journal of sustainable architecture and civil engineering 2017/2/19 environment, 2003; 12(2): 281-292. https://doi. org/10.1177/1420326x03035918 lawson t.v. building aerodynamics. london uk. imperial college press, 2001. https://doi.org/10.1142/p161 lawson, t.v. and penwarden, a.d. the effects of wind on people in the vicinity of buildings. in: proceedings 4th international conference on wind effects on buildings and structures, 1975. cambridge university press, heathrow, pp. 605-622. lien, j. and ahmed, n. indoor air quality measurement with the installation of a rooftop turbine ventilator. journal of environmental protection, 2012; 3: 1498-1508. https://doi.org/10.4236/jep.2012.311166 melbourne, w.h. and joubert, p.n. problems with wind flow at the base of tall buildings. in proceedings of the third international conference on wind effects on buildings and structures, tokyo, 1971, pp. 105-114. meroney, r.n. cfd prediction of airflow in buildings for natural ventilation. in proceedings of the 11th americas conference on wind engineering, san juan, puerto rico 2009. montazeri, h. and blocken b. cfd simulation of wind-induced pressure coefficients on buildings with and without balconies: validation and sensitivity analysis. building and environment, 2013; 60: 137149. https://doi.org/10.1016/j.buildenv.2012.11.012 murakami, s. and deguchi, k. new criteria for wind effects on pedestrians. journal of wind engineering and industrial aerodynamics, 1981; 7: 289-309. https://doi.org/10.1016/0167-6105(81)90055-6 nen, 2006. wind comfort and wind danger in the built environment, nen 8100 (in dutch) dutch standard. penwarden, a.d. acceptable wind speeds in towns. building science, 1973; 8 259-267. https://doi. org/10.1016/0007-3628(73)90008-x prasad, k., li, k., moore, e.f., bryant, r.a., johnson, a. and whetstone, j.r. greenhouse gas emissions and dispersion. nist special publication 1159, 2013. senveli, a., dizman, t. and celen, a. cfd analysis of smoke and temperature control system of an indoor parking lot with jet fans. journal of thermal engineering, 2014; 1(2): 116-130. https://doi. org/10.18186/jte.02276 simiu e. the design of buildings for wind: a guide for asce 7-10 standard users and designers for special structures. 2nd ed. new jersey, usa: john wiley & sons inc, hoboken; 2001. simiu, e. and scanlan r.h. wind effects on structures. 3rd ed. new york. wiley; 1996. soligo, m.j., irwin, p.a., williams, c.j. and schuyler, g.d. a comprehensive assessment of pedestrian comfort including thermal effects. journal of wind engineering and industrial aerodynamics, 1998; 77 & 78: 753-766. willemsen, e. and wisse, j.a. design for wind comfort in the netherlands: procedures, criteria and open research issues. journal of wind engineering and industrial aerodynamics, 2007; 95: 1541-1550. https://doi.org/10.1016/j.jweia.2007.02.006 wise, a.f.e. wind effects due to groups of buildings. in: proceedings of the royal society symposium architectural aerodynamics, session 3, effect of buildings on the local wind, london, pp 26-27 february 1970. about the authorsjennifer keenahan assistant professor1 and project engineer2 1school of civil engineering, university college dublin and 2arup dublin main research area computational fluid dynamics for the built environment address 50 ringsend road, ringsend, dublin 4. tel. 01 2334455 e-mail: jennifer.keenahan@ucd.ie reamonn mac reamoinn senior engineer arup dublin main research area computational fluid dynamics for the built environment address 50 ringsend road, ringsend, dublin 4. tel. 01 2334455 e-mail: reamonn.macreamoinn@ arup.com cristina paduano senior engineer arup dublin main research area computational fluid dynamics for the built environment address 50 ringsend road, ringsend, dublin 4. tel. 01 2334455 e-mail: cristina.paduano@arup.com journal of sustainable architecture and civil engineering 2017/3/20 48 *corresponding author: indre.grazuleviciute@ktu.lt re-functioning of inter-war modernism buildings in kaunas (lithuania): the aspect of users’ comfortreceived 2017/09/20 accepted after revision 2017/11/22 journal of sustainable architecture and civil engineering vol. 3 / no. 20 / 2017 pp. 48-57 doi 10.5755/j01.sace.20.3.19323 © kaunas university of technology re-functioning of inter-war modernism buildings in kaunas (lithuania): the aspect of users’ comfort jsace 3/20 http://dx.doi.org/10.5755/j01.sace.20.3.19323 indrė gražulevičiūtė-vileniškė*, lina šeduikytė, orinta liutikaitė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania this study is aimed at analysing the possibilities of contemporary use and re-functioning of kaunas inter-war modernism buildings from the users’ comfort point of view. for the study, we have selected the building of the house of commerce, industry and crafts designed in 1937 1939 by the well-known architect of this period v. landsbergis-zemkalnis that was continuously used and re-used for the administrative, office, and library purposes through its entire existence. in the frame of this research the analysis of literature, including the peculiarities of heritage building re-functioning from the users’ comfort point of view and the historical context of the case study building, and the field study including the photographical survey and the measurements of thermal conditions during warm (august) and cold (march – april, with central heating) seasons were carried out. the research on site has shown the favourable conditions for the users according to the contemporary standards; however, the deterioration of some building’s structures threaten its heritage values and the use possibilities in the future. it can be concluded that the prestige generated by the heritage values and social significance of kaunas interwar modernism architecture together with the appropriate thermal conditions for the users encourage sustainable renovation and re-functioning of such buildings for the needs of contemporary society. keywords: heritage building, cultural heritage, re-functioning, sustainability, inter-war modernism, thermal comfort, kaunas, lithuania. relevance of research. heritage building means a building possessing architectural, aesthetic, historic or cultural values and designated by the competent authorities (heritage…, 2013). the multifaceted significance of preservation of heritage buildings is undoubted and embedded in the international, regional, and national documents. for example, the declaration of amsterdam, adopted by the congress on the european architectural heritage and the council of europe in 1975 underlines that apart from its priceless cultural value, europe’s architectural heritage gives to the peoples the consciousness of their common history and common future; therefore, its preservation is a matter of vital importance (the declaration…, 1975). the preservation of heritage buildings for the present and future generations is related with the activities of heritage management and conservation. management of heritage object involves making conscious choices about what happens to it and includes the widest possible range of actions and decisions, such as: introduction 49 journal of sustainable architecture and civil engineering 2017/3/20 establishing the appropriate decision-making group and processes; setting up decision-making structures to implement strategies; assessing significance; deciding to open or not open a site to visitors; approving site works and physical conservation; arranging access rights or means to achieve access (such as transport) or even deciding to take no action etc. (castellanos and descamps, 2009). however, according to the international cultural tourism charter, “a primary objective for managing heritage is to communicate its significance and need for its conservation to its host community and to visitors (international..., 1999). according to f. g. weaver (1997), “architectural conservation deals with issues of prolonging the life and reliability of architectural character and integrity, such as form and style, and /or its constituent materials, such as stone, brick, glass, metal and wood. in this sense, the term refers to the professional use of a combination of science, art, craft and technology as a preservation tool”. these definitions reveal that the field of heritage preservation involves both tangible (prolonging the life span of the building, its use and re-use, preservation of the authentic fabric) and intangible (influence on local identity, communication of significance etc.) aspects and their interactions enabling present and future generations to benefit from heritage buildings. the potentially long and hardly definable life span of heritage buildings determines the importance of their continuous adaptation to the needs of changing society including re-use and re-functioning without losing both tangible and intangible values. according to g. golmakani (2011), sustaining heritage buildings by restoring and re-using them with their original character is important for development of culture. the aim of research is to analyse the possibilities of contemporary use and re-refunctioning of kaunas inter-war modernism buildings from the users’ comfort point of view both concentrating on the case of the building of the house of commerce, industry and crafts (sometimes translated as commerce, industry and crafts palace) and the measurements carried out in it and the analysis of the wider context of the problem including both literature review regarding building re-functioning and users comfort and the historical context of the building. the building of the house of commerce, industry and crafts designed in 1937 1939 by the well-known architect of this period v. landsbergis-žemkalnis that was selected for this study as the representative object of high architectural quality that was continuously used and re-used for the administrative, office, and library purposes through its entire existence and demonstrates well the refunctioning possibilities and maintenance challenges of the modernist building of inter-war era. the applied research methods include the analysis of foreign and lithuanian literature, the photographical survey on site, and the measurements of thermal conditions during the warm and cold seasons. refunctioning of heritage buildings and the users’ comfort the practice of adapting to new functions an existing building is almost as old as building practice itself and the conservation of historic buildings is always facilitated by their socially useful purposes (philokyprou, 2014). history of architecture and experience of heritage preservation demonstrate the importance of continuous use of heritage building for the maintenance of its good physical condition and its role in community and society. for example, the most known and well preserved are those ancient roman temples that in the course of time were used as churches, museums etc. the analysis of heritage preservation terminology demonstrates that different terms exist to define the aspects of use for the authentic and other functions of heritage building. for example, the term “re-use” in general can be defined as “to use again” or “the use of a material more than once in its same form for the same purpose” (leblanc, 2011) and in the context of heritage buildings it more denotes to the situation when once abandoned or inappropriately used building can be re-used again for the same original or new function. in other words, term “re-use” may actually mean the change of function, but not necessarily. the term “convert” or “conversion” in the field of architecture and heritage preservation means “to change the use of a building” (lebliterature and theory journal of sustainable architecture and civil engineering 2017/3/20 50 lanc, 2011) and related necessary interventions in to the building’s fabric. similar meaning can be attributed to the term “adaptive re-use”, which implies “the recycling of an older structure often for a new function. extensive restoration or rehabilitation of both the interior and exterior is usually involved” (leblanc, 2011). the art & architecture thesaurus of getty research institution defines adaptive re-use as the “conversion of buildings”. some authors, analyzing the changes of functions and related interventions of heritage buildings use the term “re-functioning” (golmakani, 2011), this term first of all implies the adaptation of the building to the new function, and may imply, but not necessarily, the intervention into the built fabric. the term “re-functioning” is used in other contexts as well, for example, in the field of german modernist theatre re-functioning means the aesthetics that is intended to “intervene in the process of shaping society” (encyclo…, 2014). the idea that changing the function and the physical fabric of the heritage building changes its meanings and significances (its role in the lives of individuals, community, and society) is relevant in the field of heritage preservation as well. consequently, in the context of this work, we will mainly use the term “re-functioning” because of its flexible and encompassing meaning. the literature review has demonstrated that re-functioning of heritage buildings for various purposes is widespread and widely analyzed issue. according to m. philokyprou (2014), in more recent times the phenomenon of heritage buildings re-functioning has become more widespread as both public institutions and building owners appreciate the value of historic properties and decide to prolong their useful life adapting them to the changing needs of society. m. highfield (1987), m. binney et al. (1991), k. powell (1999) and many others had addressed this question from various perspectives. for example, m. philokyprou (2014) had analysed the case of re-functioning of historic buildings in the centre of limassol (cyprus) for the needs of newly instituted university. m ulusoy et al. (2013) analyzed re-functioning of heritage buildings in the context of sustainability. the abandoned and derelict industrial buildings after the deindustrialization of europe, many of them possessing heritage values, receive the particular attention in this regard. m. binney et al. (1991) published the guide to practical ways of re-using mills, warehouses, maltings and other british industrial buildings. g. golmakani (2011) had analyzed the re-functioning potential of industrial heritage buildings in north cyprus. e. mengusoglu and m. boyacioglu (2013) presented the case of re-functioning of industrial heritage for residential purposes in manchester. the issue of heritage buildings re-functioning has wider implications as well including urban regeneration and sustainability goals. according to m. philokyprou (2014), the imperative of extension of the life cycle of heritage building is also related to various sustainability goals. she underlines that the re-use of existing buildings is one of the highest forms of sustainable design. the paradigm of sustainability regarding the heritage buildings, however, requires not only minimizing the waste generation and the use of resources, maintaining the identity of the place and community, but also energy savings and the appropriate living and working conditions for the users of heritage buildings. reviewed studies (bellia et al., 2015; burattini et al., 2015; todorovic, 2012; todorovic et al., 2015 and many others) had demonstrated that it is possible to improve the energy performance of an existing building achieving a significant energy saving with the respect of the building architecture, shape, function and the surrounding landscape (burattini et al., 2015). it is possible to presume that some historic buildings are inherently sustainable including the users comfort as well; taking into account the original climatic adaptations of historic buildings, contemporary sustainable technologies can supplement their inherent sustainable features (todorovic, 2012). for example, originally heritage buildings have natural ventilation. if all indoor air quality and thermal comfort parameters are kept, these buildings are meeting sustainability requirements, as no energy is needed for cooling. in some cases, compromises are necessary and mechanical ventilation should be introduced if we want to continue using heritage building. in most cases with natural ventilation, the biggest concern is overheating. new techniques are presented by scientists to assess thermal comfort of a naturally ventilated buildings (chen et al., 2017; hurtado et al., 2017). 51 journal of sustainable architecture and civil engineering 2017/3/20 building users comfort includes thermal, visual, and acoustic comfort and air quality (occupant…, 2017). several studies have shown (geng et al., 2017; seppanen and fisk, 2006; fisk et al., 2005) that thermal comfort and indoor air quality have a crucial impact on employee’s productivity and health. if heritage buildings are used as offices, they have to meet thermal comfort requirements. in this study we address the issue of the thermal comfort, which is relevant in lithuanian climate with the expressed cold and warm seasons. kaunas interwar modernism and the house of commerce, industry and crafts with the passage of time, ongoing social changes, and the development of heritage preservation field the notion of heritage has expanded both from the point of view of typology and the age of the object, that is considered as valuable. according to j. jokilehto (2007), “the cultural heritage <…> now also embraces the records left behind by the 20th century. <…> the idea of the heritage has been broadened to include both the human and the natural environment, both architectural complexes and archeological sites, not only the rural heritage and the country site, but also the urban, technical or industrial heritage, industrial design and street furniture.” the history of the inter-war era architecture of modernism of the second largest lithuanian city kaunas and its patrimonialization well reflect these developments in the field of heritage preservation. not so long ago this architectural heritage was appreciated only in the limited circle of professionals and enthusiasts, interested in the variety of architectural manifestations of the modern movement, the research into this architectural period was limited by the soviet regime as well; now it is known as an outstanding and complex phenomenon and increasingly advertised both in the local, national and international contexts. kaunas inter-war modernism architecture was recently awarded the european heritage label; its inclusion into unesco world heritage list is anticipated as well. cultural context. the cultural context of the building under analysis is shaped by several events and trends of its era, including among others: _ the status of temporary capital of lithuania attributed to the city of kaunas in 1920, which had encouraged the concentration of institutions, population, professionals, cultural processes, the building boom, the development of infrastructure, and the search for the new identity and new ways of architectural expression. according to j. kančienė (2007), as a result of this building boom, in the fourth decade of the 20th century kaunas looked much less provincial compared to earlier decades: architectural expression shifted towards then fashionable functionalism, asphalted streets stretched with wide sidewalks, abundant lighting, buses ran instead of horse-drawn trams, city was full with taxis and private cars etc. according to the statistics, the construction was the most intense in 1931, when the world was already in the deep economic crisis. _ the development of modernism in architecture and design at the beginning of the 20th century, which had acquired different forms depending on a variety of cultural, social, political and other conditions in different contexts ranging from rational, economically efficient socially oriented trends to “cold and anonymous” international style or even monumental representative buildings, from total abandonment of decorative non-functional elements and attachment to any architectural tradition to integration of vernacular or ethnic aesthetics or even the features of classical architecture into design. in some instances, despite its superficial simplicity and uniformity, modernist architecture can integrate several of above-mentioned trends and gain distinctive local forms: “the new tendencies of modernism that spread through the most part of the western world after world war i soon found their way into the young republic of lithuania. local architects, that were coming home after the studies in western european universities brought back the new architectural ideas, and transformed them into distinctive local form, that was later named kaunas school of architecture (laurinatis, 2017).” journal of sustainable architecture and civil engineering 2017/3/20 52 house of commerce, industry and crafts. the search for the new architectural expression was started in the inter-war lithuania’s temporary capital. initially the retrospective architecture imitating and interpreting the historical forms was predominant; however, it was soon replaced with more functionalist approaches (kančienė, 2007). each of the architects working in this trend “had their own style, marked by their unique variations of modernist elements – either by fusing them with classical architecture, search for so-called „national style“, or just by simply trying to adjust those ideas for the local conditions (laurinaitis, 2017)”. the design and construction of the building of the house of commerce, industry and crafts demonstrates the attitude of that era towards the building important both in the architectural and institutional context. the first design competition was held in 1937 with the intended location of the building near the museum complex on donelaičio street. 28 projects were presented and the realization was entrusted to the second place winner architect vytautas landsbergis-žemkalnis. although the building was not realized in this location. the alternative location was selected at the beginning of donelaičio street, which had gained the gradual significance as a representative urban axis. the researchers note, that the architect had just slightly changed the previous design, made its “mirror reflection” and adapted to the site (kančienė and minkevičius 1993; laurinaitis, 2012). in the 18th of february 1939 the building designed by v. landsbergis-žemkalnis was opened. the design of the building embodies the more classical approaches applied to representative building of the state at that time. even if the architectural forms and details are strongly rationalized, the arches and emphasized pilasters constitute an important part in the composition of the building. the luxurious interiors designed by the architect of the building are decorated with folk motifs. the importance of the building is emphasized by the works of art in the interior and exterior by the artists famous at that time – bronius pundzius, stasys ušinskas, petras kalpokas (kančienė and minkevičius 1993; laurinaitis, 2012). fig. 1 kaunas modernism architecture (in the postcards of the inter-war era) as a paradoxical merging of international trends and national style development, modernist minimalism and ornament, simplicity and grandeur and such is the building under analysis – the house of commerce, industry and crafts (first at the top) 53 journal of sustainable architecture and civil engineering 2017/3/20 in 1940 after the soviet occupation the institution of house of commerce, industry and crafts was dismissed and the building was nationalized (kaunas…, 2010). on the 1st of october 1950 the public library was instituted in the building (kaunas…, 2016). the largest part of the building is still used by the subdivision of kaunas county public library and houses the department of music publications, the department of rare and antique publications, and the department of children literature (kaunas…, 2016). in 1991 the institution of house of commerce, industry and crafts abolished by the soviet regime was restored and currently occupies part of their historic building as well. such favourable function conditioned that the building has survived in a satisfactory condition till present times. however, already in 1960 the structural overload and deformation problems due to the storage of library funds in the building caused the need to transfer part of these funds to another location (kaunas…, 2016). the building was repaired in 1968 and the roof was repaired approximately two decades ago, although works were of low quality. with the passage of time the problems of the building have aggravated. the leaking roof and the spreading mold threatens both building structures and its valuable features and the collections of valuable publications accumulated by the library (anilionytė and alper, 2016). the physical condition of the building, the safety of historic artworks and furniture as well as the conditions, in which the funds of library are stored still raise concern of institutions and society. this interest has intensified with the award of the european heritage label to kaunas inter-war modernism and consequent marking the building with the table with the european heritage logo. fig. 2 present exterior and interior condition of the building of the house of commerce, industry and crafts demonstrates the signs of decay. photographs by the authors empirical study and results several international standards and guidelines from international organization for standardization (iso) and european committee for standardization (cen) are giving requirements related to comfort and health. studies are showing that comfortable room temperatures, good indoor air quality and effective ventilation are increasing the performance of people (olesen, 2012). journal of sustainable architecture and civil engineering 2017/3/20 54 as mentioned before, a subdivision of kaunas county public library and offices of the institution of house of commerce, industry and crafts are located in the tested building. two offices (fig. 3) and conference hall were selected for the measurements. in each office, 3 people have a working place. fig. 3 the offices and the conference hall in the house of commerce, industry and crafts where the measurements of temperature, relative humidity and co2 concentration were carried out for the measurements of temperature and relative humidity hobo sensors were used. sensors were attached to the stand at 0.1 m and 1.1 m height, to check temperature differences for the ankle and for seated person level. temperature and relative humidity measurements were carried out for one month during cold (17 march – 17 april, 2017) and warm (1 31 august, 2017) seasons. during the cold season, the central heating was on. the interval of sampling – 10 min. measurements of carbon dioxide (co2) concentration were used as an indicator of indoor air quality and ventilation effectiveness. fluke 975 was used for co2 measurements. measurements of co2 concentration were performed during the warm season in one of the tested office rooms. results of the measured temperature and relative humidity (average values) are presented in table 1. data of working day (starting from 8 a.m. until 5 p.m.) was analysed. results show, that the average temperature in the tested offices during the cold season was slightly higher than recommended by the hn 42:2009 requirements (22°c). however, in the conference hall, the temperature was almost meeting the critical lowest value of 18°c. temperature table 1 average temperature (t) and relative humidity (rh) values measured in the tested offices and conference hall during the cold and warm seasons parameter/ the height of the instrument cold season warm season tested area 0.1 m 1.1 m 0.1 m 1.1 m t, °c 22.7 23.1 25.3 25.4 office nr.31 rh, % 26 25 45 43 t, °c 20.4 22.2 24.1 24.2 office nr.37 rh, % 27 25 51 44 t, °c 18.7 19.4 23.3 23.6 conference hall rh, % 30 29 54 54 55 journal of sustainable architecture and civil engineering 2017/3/20 conclusions references differences at different heights were not significant and were not exceeding 3°c. relative humidity was lower than 30% and was not meeting hn 42:2009 requirements. however, this is a common problem in the office buildings during the cold season. the results show, that tested parameters are meeting the requirements during the warm season. the average co2 concentration measured during the working days of warm season was 575 ppm. 1 the preservation and communication of heritage values are inseparable from the continu-ous use of heritage buildings for the changing needs of the evolving society. in this context it is necessary to acknowledge that some outstanding public buildings of inter-war modernism located in the centre of kaunas awarded the honour to be marked with the table with the european heritage logo are just partially used and stand almost abandoned raising concerns of further re-functioning and preservation. such situation means that the social, economic, and cultural potential of these buildings is just partially employed of not employed at all. 2 the building of the house of commerce, industry and crafts was selected for the study as an example of continuous use and re-functioning of the heritage building. despite the need of renovation of the interior, exterior and some building structures, the measurements demonstrate the favourable conditions for office workers both in cold and warm seasons. results in tested offices during the cold season are showing that the average temperature is slightly higher than recommended by the hn 42:2009 (22°c). however, the difference is not significant and cannot affect the people working in these offices. results of warm season are showing that all the parameters are meeting the hn 42:2009 requirements. taking into account that this heritage building has natural ventilation and offices are not overheated during the warm season it can be concluded that the building is meeting related sustainability requirements and after corresponding renovations can be successfully used for the present needs. 3 social engagement and awareness of values of heritage buildings are crucial for their con-tinuous functioning, re-functioning and preservation. however, their inherent sustainability and adaptability are important as well as the case of the house of commerce, industry and crafts demonstrates. both the prestige and values of heritage buildings including their often favourable location and their sustainability and re-functioning potential should encourage national and international investors and company leaders to consider having the offices in heritage buildings. anilionytė j., alper m. kauno apskrities bibliotekos tarpukario pastatas nesulaukia remonto 2016 (accessed 15 july 2017). available at: http://kauno. diena.lt/naujienos/kaunas/miesto-pulsas/trukstant-lesu-netvarkomas-kauno-apskrities-bibliotekos-tarpukario-pastatas-764677 bellia l., alfano f.r.d., 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reconstruction of old buildings. new york: laurence king; 1999. seppanen o.a., fisk w. some quantitative relations between indoor environmental quality and work performance or health. hvac&research, 2006; 12 (4): 957-973. https://doi.org/10.1080/10789669.20 06.10391446 the art & architecture thesaurus of getty research (accessed 15 july 2017). available at: http://www. getty.edu/vow/aatservlet?english=n&find=conversion&logic=and&page=1&note= todorovic m.s., ecim-duric o., nikolic s., ristic s., polic-radovanovic s. historic building’s holistic and sustainable deep energy refurbishment via bps, energy efficiency and renewable energy a case study. buildings, 2015; 95: 130-137. https://doi. org/10.1016/j.enbuild.2014.11.011 57 journal of sustainable architecture and civil engineering 2017/3/20 about the authors indrė gražulevičiūtėvileniškė assoc. professor kaunas university of technology, faculty of civil engineering and architecture main research areas valuation and preservation of cultural heritage, management of rural-urban interface, sustainable architecture address kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 451546 e-mail: indre.grazuleviciute@ktu.lt lina šeduikytė assoc. professor kaunas university of technology, faculty of civil engineering and architecture main research areas sustainability, indoor air quality, renovation address kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300 492 e-mail: lina.seduikyte@ktu.lt orinta liutkaitė master student kaunas university of technology, faculty of civil engineering and architecture main research areas sustainability, indoor air quality, renovation address kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 300 492 e-mail: orinta.liutikaite@ktu.edu todorovic m.s. in search of a holistic, sustainable and replicable model for complete energy refurbishment in historic buildings. consevartion science in cultural heritage. historical-technical journal. 2012; 12 (accessed 15 july 2017). available at: https://conservation-science.unibo.it/article/ view/3381 ulusoy m., erdogan e., erdogan h.a., orala m. re-using of the historical buildings in the context of sustainability: an architectural design studio study on old girls teacher training school. international archives of the photogrammetry, remote sensing and spatial information sciences, 2013; 653657. https:// doi.org/10.5194/isprsarchives-xl-5-w2-653-2013 weaver, f. g. conserving buildings: a manual of techniques and materials. john wiley & sons inc; 1997. journal of sustainable architecture and civil engineering 2015/3/12 44 journal of sustainable architecture and civil engineering vol. 3 / no. 12 / 2015 pp. 44-56 doi 10.5755/j01.sace.12.3.13022 © kaunas university of technology received 2015/06/03 accepted after revision 2015/08/29 analysis of legal and theoretical framework creating the methodology of visual pollution assessment for natural landscapes jsace 3/12 analysis of legal and theoretical framework creating the methodology of visual pollution assessment for natural landscapes corresponding author: jurate.kamicaityte@ktu.lt http://dx.doi.org/10.5755/j01.sace.12.3.13022 jūratė kamičaitytė-virbašienė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania giedrė godienė lithuanian geographical society, a. baranausko st. 8, lt-04224 vilnius, lithuania fulfilling the requirements of european landscape convention (2002) and following the statements of the national landscape policy of the republic of lithuania (2004) in 2014 the ministry of environment of the republic of lithuania initiated creation of methodology of the assessment of visual pollution to natural landscape complexes and objects. in order to prepare the methodology legal and theoretical framework of visual impact assessment (via) was analysed and evaluated. the analysis showed that international legal documents create all preconditions for the via at the national level. the national legislation requires the avoidance of visual pollution (in the state parks regulations), but there are no recommendations how to evaluate visual impact. foreign countries in the field of via, unlike lithuania, have validated concepts of landscape visual quality and planned activity or object visual impact assessment; systemic and objective methodological recommendations of visual impact assessment, which are used in practical activities of planning and design. methodologies used by lithuanian authors are well developed theoretically and intended for the overall evaluation of landscape visual quality or via, designation of landscape visual quality classes, evaluation of visual spaces (vs) indicators, establishment of vs visual resistance and sensitivity. parts of some works can be used for the creation of methodology of visual pollution (negative visual impact) assessment. keywords: natural landscape, visual impact assessment, visual pollution. by ratifying the european landscape convention (elc) (2002), lithuania, together with other countries, acknowledged that the landscape contributes to the formation of local cultures and that it is a basic component of the european natural and cultural heritage, contributing to human well-being and consolidation of the european identity. however, in recent times due to the socio-economic, technological development, globalization, and other factors landscape is changing rapidly, and its quality support actions become increasingly important for the sustaining main qualitative (ecologic, aesthetic, social, cultural, economic, etc.) features of it. landscape visual quality is important to society from aesthetic, ecologic, historic and economic points of view. it is a public resource and environmental asset, which is a valuable part of landscape as a geo-cultural system. introduction 45 journal of sustainable architecture and civil engineering 2015/3/12 human activities (construction, agriculture, mineral extraction, deforestation, outdoor advertising, etc.) cause landscape anthropogenisation. they can result in the creation of cultural landscapes with positive qualitative indicators or low quality degraded landscapes. various ecological impacts on the natural structure of landscape are assessed in order to avoid the decrease of landscape quality and formation of degraded landscape. visual quality of landscape as one of the qualitative aspects of it decreases too and assessment of visual impact helps to prevent the loss of landscape visual-aesthetic potential. negative visual impact could be defined as visual pollution. this phenomenon must be identified, assessed and regulated. especially in the case of natural, protected areas, because they are more sensitive and their visual capacity is quite low comparing with man-made landscapes (townscapes). regard to this situation and fulfilling the requirements of elc (2002) and following the statements of the national landscape policy of the republic of lithuania (2004) in 2014 the ministry of environment of the republic of lithuania initiated creation of methodology of the assessment of visual pollution to natural landscape complexes and objects. developing the methodology the legal framework (international and national legislation) of the assessment of visual pollution (negative visual impact) on landscape was analysed. lithuanian (scientific works of m. purvinas (1975, 1983a, 1983b, 1990), p. kavaliauskas (2011), j. abromas (2014), etc.) and world-wide experience (united states (environmental impact..., 2008; turner, 2003; visual resource... 2001; manual 8431..., 2012), united kingdom (morris and therivel, 2001; guidelines for landscape…, 2002) germany, spain, new zealand, south african republic, australia (evaluation of methodologies..., 2012; böhm, 1996; turner, 2003; guidelines for..., 2005)) in the fields of the assessment of landscape visual-aesthetic potential and visual impact assessment as the theoretical framework was analysed too. the aim of the paper is to review legal and theoretical framework of visual impact assessment (via) and to present the main legal and theoretical premises of visual pollution assessment (vpa) for natural landscapes. in order to get the research results we performed literature analysis. we analysed theoretical issues of visual impact assessment (via) in united kingdom, united states, germany, spain, new zealand, south african republic, and australia (environmental impact..., 2008; turner, 2003; visual resource... 2001; manual 8431..., 2012; morris and therivel, 2001; guidelines for landscape…, 2002; evaluation of methodologies..., 2012; böhm, 1996; guidelines for..., 2005); reviewed lithuanian experience in the fields of the assessment of landscape visual-aesthetic potential and visual impact assessment (scientific works of m. purvinas (1975, 1983a, 1983b, 1990), p. kavaliauskas (2011), r. skorupskas and v. vasilevskaja (2014), j. abromas (2014), etc.). lithuanian and worldwide experience was compared and evaluated considering the concept of visual pollution (negative visual impact) and the necessity of its assessment for natural landscapes. the main criteria of material selection and analysis were the following: formulation of scientifically valid notion of visual pollution (negative visual impact), identification and description of comparative indicators (physical and visual characteristics) of landscape and the object of visual pollution, clarification of the main stages of vpa, and determination of the content of each stage of vpa. the legal framework (international and national legislation) of the assessment of visual pollution (negative visual impact) to landscape was analysed too. the statements of eu directive on environmental impact assessment (85/337/eec) (amendment 2014/52/eu), eu directive on strategic environmental assessment of plans and programs (2001/42/ec), european landscape convention (2002), the recommendation cm/rec(2008)3 of the committee of ministers to member states on the guidelines for the implementation of the european landscape convention, national political documents (national landscape policy (2004)), studies (national landscape study (2013)), laws (law on environment protection (1996), law on protected areas (2001), law on immethods journal of sustainable architecture and civil engineering 2015/3/12 46 movable cultural heritage protection (2004), etc.) plans (national landscape management plan (2015)), and other documents were reviewed. afterwards concluding statements about common legal preconditions for the assessment of visual pollution were made. legal framework internatio-al level the legal preconditions for the assessment of the impact on landscape relay on the requirements of the eu directive on environmental impact assessment (eia) (85/337/eec) (amendment 2014/52/eu) and eu directive on strategic environmental assessment (sea) of plans and programs (2001/42/ec), which applies to a wide range of public and private projects. eia and sea requires assessing the impact on landscape, and particularly, to indicate significant effects on the all protected areas (council directive..., 1985; directive 2001/42/ec..., 2001). european landscape convention (2002) promotes the protection, management and planning of european landscapes. this treaty focuses attention on both the character of the area and the human perspective, perception of this area. it defines “landscape” as an area, perceived by people, whose character is the result of the action and interaction of natural and/or human factors. elc implementation guidelines (recommendation cm/rec(2008)3..., 2008) indicate the need to integrate landscape issues (analyses, studies, plans, etc.) into all sectorial policies and eia system, even more – recommend to establish specific procedure for landscape evaluation of projects for which official permission is required, but which are not yet a subject of the eia or sea. the documentation should: show how the project fits into the different contexts (the “immediate” context of a development proposal, and its “halfway” and “distant” contexts), which present problems of visibility and intervisibility of sites in the largest areas; show the link with materials, colours and building techniques; describe the impact on biotic and abiotic aspects; reveal the conditions of the sites and contexts before work is carried out; demonstrate the consistency of the project characteristics with the contexts; simulate how the site will look afterwards; demonstrate that the project conforms with its landscape planning and development instruments (plans, charters, etc.) and landscape quality objectives, where they exist; assess the effects of the proposed development on the places concerned and introduce, where necessary, mitigation measures which will ensure the maintenance of good landscape quality in those sites and compensation measures contributing to environmental quality. national level implementing elc, strategic national landscape policy (nlp) (2004) document was approved by the government of the republic of lithuania in 2004. this strategy provides main objectives and general guidelines for the future actions. among the main tasks related to the strengthening of aesthetical values protection there are the following tasks: ensuring appropriate management, use, planning and sustainable development of landscape safeguarding the main features and identity of the country; maintaining and enhancing existing biological and landscape diversity, the spatial structure and the ecological potential of the landscape; optimizing trends of the development of cultural landscape; harmonizing its architectural-spatial composition. while maintaining and strengthening aesthetical functions of landscape, it is foreseen to: sustain and enlarge the spatial expression of landscape; sustain and regulate informative diversity of landscape; enhance the individuality of landscape structures; seek for consistency between natural and artificial features. in relation with these nlp tasks, the ministry of environment initiated development of the national landscape study in 2013. the study (2013) systematizes general concepts, basic determinants and pressures on the landscape, ascertaining its types and morphology based on natural character, technogenic structure, spatial geochemical processes, aesthetical features, potential and spatial differentiation in the territory of lithuania. the study serves as the main scientific basis, the general results 47 journal of sustainable architecture and civil engineering 2015/3/12 professional landscape information for the state and local authorities, planners, etc. there are distinguished areas of particular character, rarity, specific environmental sensitivity or aesthetic peculiarity. implementing the nlp, national landscape management plan is prepared on the basis of national landscape study and it is foreseen to be adopted in 2015. the main goals of this document (nacionalinis kraštovaizdžio…, 2015) are: to distinguish main functional structures of landscape and formulate quality objectives for them. the plan provides territorial differentiation of aesthetical potential of lithuania and enables to embed legally and spatially protection measures of aesthetical resources. the legal preconditions for visual impact assessment on landscape are laid out in legal acts, legitimizing landscape structure, character, features and functions as values of international, national, regional or local importance. the hierarchical system consists of laws on environment protection, protected areas (pa), immovable cultural heritage protection (ichp), coastal strip, land, forests, territorial planning, and others, governmental decision on special conditions of land and forests use, special planning documents (borders and zoning plans, management plans) and different regulations of particular protected areas, individual and typical regulations of cultural heritage objects protection, regional architectural regulations of protected areas, etc. the law on environment protection (1996) regulates social relations in the environment protection. it states the main components and characteristics of environment and defines concept of potential harm on environment. the potential harm to landscape is indicated as made by direct or indirect impact on protected landscapes and their character, the change and impairment of their functions, features, which are important to environment and society, the worsening of the state of protected areas when there is a fact of controversies with requirements of environment protection. the protection of visual attributes and aesthetical potential of landscape is a subject of the law on protected areas (pa) (2001) and the law on immovable cultural heritage protection (ichp) (2004). natural and particularly cultural values, the aesthetical value of territories and objects are recognized as an important part of general value. according to the pa and ichp laws, in all protected areas, territories and objects of immovable cultural and natural heritage all activities, which could harm their valuable features, ability to percept them, change the landscape character in their territories or surroundings are prohibited. the same regulation is applied for the recreational areas in state parks. the articles 9 and 13 of the law on pa prohibit to plant trees, which can diminish ability to observe panoramas of historical, cultural and aesthetical value, place commercial advertising boards, perform any activity, which can harm protected characteristics and objects, not related to the protected features in all state parks, natural and complex reserves. design, reconstruction and construction of buildings in state parks are allowed only according to the requirements of legal acts, taking into account regional character of traditional architecture and landscape. for the protection of natural and cultural values, specific visual preservation zones are established covering the areas from which values could be observed. according the laws of pa (article 18), and ichp (article 11) activities, that could harm surroundings of valuable territory, object; could diminish optimal perception of values or the landscape in these visual preservation zones are prohibited. such zones surround state parks, recreational areas, nature and cultural heritage monuments. the activities in these zones and general provisions on the use of protected areas are specifically regulated by the governmental decision on special conditions of land and forests use (1992). among the restrictions are prohibitions to construct buildings which can diminish aesthetical value of the landscape and plant trees, blocking up the historically, culturally and aesthetically valuable panoramas. in the state parks preservation zones there is prohibited to construct buildings, if this can reduce distinctness of natural relief and increase visual pollution of the park area. among other requirements, in the preservation zones of nature monuments it is prohibited to harm, change the main features of the relief which forms character of the area, construct buildings and constructions, not related to the protected values exposition or management. mostly journal of sustainable architecture and civil engineering 2015/3/12 48 relying on the visual motives (visual disturbance), in almost all reserves it is prohibited to place container houses and other not used transport vehicles, garages. in landscape of geomorphologic reserves it is prohibited to lay down air electric or communication lines and place wind power plants, plant forest and trees groups which can unify, even relief. legislation requirements are much more generalized safeguarding the aesthetical values developing the landscape. the law on construction (2001) article 5 states that the architecture of structure has to fit in landscape. the protection of landscape visual character is encrypted in the law on advertising (2013). according this law, it is prohibited to place free standing billboards in and above the roads, roads lanes and their protection zones, in the streets, if it could diminish visibility, threaten traffic safety; place outdoor advertisement in the areas of natural and complex reserves, state parks, if they are not related to the protected subjects (except city areas). installation of advertising billboards in the areas of cultural heritage objects, territories and their preservation zones, other protected areas is allowed only with special permission of the responsible authority. the necessity to prepare special territorial planning document of local or regional level, i.e. plan on regulation of outdoor advertising or relevant part in complex master plan, which must ensure that the advertising billboards will meet requirements of legislation on construction, planning, landscape and cultural heritage protection, and assess the potential visual impact on landscape is specified. implementing eu directives of eia and sea the procedure of environmental impact assessment (including landscape) is organized by the law on the assessment of environmental impact of the planned economic activity (2005) and partly by the law on territorial planning (2013). national law on eia describes the landscape as an object of eia, states necessity to indicate the impact on landscape, and set mitigation measures. it focuses on analysis of such characteristics of landscape as: regionality, structure, diversity, geomorphology, hydrographical network, afforestation. the need for visual assessment of the planned activity is foreseen. subordinating legislation stresses need to indicate cases when planned activity can cause short or long term negative visual impact on the valuable landscape, cultural heritage objects and territories and other important areas. regulation on eia program and report preparation (2005) states the need to perform visibility analysis of the planned object/activity from the various points; to present information about the viewing points, level of their equipment and evaluate the impact on possible visitors’ number changes. the increase of the general ecological and aesthetical potential of the territory is listed among the possible mitigation measures. the requirement to develop scheme of the planned activity impact assessment on aesthetical, recreational resources is specified. the manual of sea sets requirement to assess impact of the plans and programs on landscape, and to analyze what it is estimated impact of planned alternatives on the both protected and not protected valuable landscape and its eco-recreational and visual recourses (2006). there are not many activities, which have specific methodological recommendations of eia: landfills (2002); hydroelectric power plants (2003), wind power plants (2003), lake cleaning (2004). all mentioned documents point out the need for visual assessment of these activities at the same time and implicate possibility that these constructions or actions can cause visual impact and can be visually harmful. the methodological recommendations of eia of landfills (2002) require to provide information on landscape type, character, land use, recreational areas, to assess the impact on natural and urban landscapes, their aesthetical potential, nature frame and protected areas, visibility from different observation points, to analyze if the planned activity will fit into the landscape, to specify the necessary visual impact mitigation measures. it is recommended, that the report of wind power plants eia should contain landscape character analysis of the affected area (type, structure, diversity, cultural values, traditionality, regional importance, aesthetic features, main observation points, panoramas, touristic and recreational 49 journal of sustainable architecture and civil engineering 2015/3/12 objects and territories), evaluation of the distance to protected areas, urban zones, roads, touristic routes, recreational areas and objects (2003). the scope of the recommended visual assessment is the following: possible changes of the visual features of landscape in the site and surroundings, the visual importance of wind power plant for the general visual character of the area. it is recommended to assess the direct and indirect visual impact form the all the significant view points and touristic and main auto-routes, residential areas, impact on important panoramas. the document denotes possibility of large impact of wind power plant constructions on the traditional, protected landscape, all the areas of natural, cultural, scientific and aesthetical significance, the ability to reach and observe protected values and recreational areas of the affected territories, diminishing of the recreational resources and the changes of the recreational conditions. summarizing the analysis of the legal framework it can be said that national legislation: _ declares aesthetical character, aesthetical features or elements (aesthetically valuable panoramas, silhouettes, dominants, traditional architecture style, etc.) of the particular areas and whole landscape as national values; _ defends ability to admire valuable territories and objects – it is prohibited to obstruct protected areas and objects, recreational areas, panoramas of significant value; _ partly interferes the development of the landscape informational field, architectural form; _ indicating the cases in which eia process has to be applied and specifying the critically harmful impact on landscape (prohibited activities) indirectly notes these activities and their material shape as visual pollution; _ formulates the need for visual evaluation, assessment; preparation of aesthetical and recreational resources assessment schemes, but does not regulate the methods, means, information resources, does not specify content of visual studies and classification of possible impact significance; _ requires the avoidance of visual pollution (in the state parks regulations), but there are no recommendations how to evaluate visual impact. theoretical framework international experience the concept of environmental impact assessment (eia) originated in united states, partly because of its extra-rigid system of zoning. planning control in some american states was much less comprehensive than in europe and there was great public concern about the harmful affect which individual development projects were having on the environment. the national environmental policy act (nepa) of 1969 became a model for similar legislation throughout the world (environmental impact..., 2008). this act also states that all americans have the right to aesthetically attractive environment. eia is understood as evaluation of impact of every aspect of the planned object or activity on every aspect of environment. the matrix of evaluation of aspects interaction is used for this purpose. there is evaluated impact of project earthworks, waterworks, vegetation, paving, walling and building on natural environment (physical and biological), social environment (circulation and recreation), and spatial environment (views, spaces, skylines) (turner, 2003; visual resource..., 2001). project correspondence with visual resources management objectives is evaluated and possible negative impact is mitigated according contrast rating method developed by bureau of land management. a visual contrast rating process involves comparing the project features with the major features in the existing landscape using the basic design elements of form, line, colour, and texture. the degree to which a management activity affects the visual quality of landscape depends on the visual contrast created between a project and the existing landscape. this assessment process provides the means for determining visual impacts and for journal of sustainable architecture and civil engineering 2015/3/12 50 identifying measures to mitigate these impacts. project features which repeat the basic design elements found in landscape are visually compatible with the contextual environment. project features which make contrast with the contextual environment according the basic design elements are assessed as positively or negatively influencing landscape visual quality taking into account visual environment management objectives. the basic design elements are the main measures to achieve harmony of the project and environment reducing the negative visual impact. the main steps in the contrast rating process (manual 8431..., 2012) are the following: project description, identification of visual resources management objectives, selection of key observation points, preparation of visual simulations and completion of the contrast rating. in 1995 landscape institute (united kingdom) published guidelines for landscape and visual impact assessment (via) for the first time. visual impact is defined as a change in the appearance of the landscape as a result of development which can be positive (improvement) or negative (detraction) (morris and therivel, 2001; guidelines for landscape…, 2002). the main stages of visual impact assessment are: screening (determines the need of eia) and scoping (identifies the scope and content of eia); project description and description, classification and evaluation of visual resources of surrounding landscape; the systematic identification of potential impacts, prediction of their magnitude, and assessment of their significance; establishment of measures to avoid, reduce or offset negative effects of the development proposals. during the process of via the type and magnitude of visual impact of the proposed development is determined according its visual compatibility with the surroundings (for ex., massing, height, shape, proportion and rhythms of building elements, colours and materials used) and the role of it in the visual environment: formation of visual obstruction (for ex., blocking of views towards existing landscape features; or existing/planned view corridors towards landmarks and notable features) or improvement of visual quality (for ex., clearance of visual obstruction and blight, appealing design features that enhance attractiveness of the landscape). a very important stage of via is evaluation of visual impact significance. impact significance is a combination of impact magnitude and the sensitivity of the receiving landscape and viewers. the sensitivity of the landscape potentially affected by the proposed development is based on the degree to which the landscape is able to accommodate change without unacceptable effects on its character. the most sensitive is protected landscape. the criteria of landscape sensitivity to the proposed development are the following: rarity and representativity, social significance, visual quality, localization of visual pollution, distinctiveness and identity, conservation interests, professional and public opinion. for ex.: sensitive landscape and large change results in a high significance of impact, landscape of law sensitivity and large change results in a moderate significance of impact. the other countries have prepared methodologies of via considering their landscape peculiarities and experience of united states and united kingdom (evaluation of methodologies..., 2012; böhm, 1996; turner, 2003): _ in spain there is used via methodology structure and content of which is based on the via methodological principles of the united states (böhm, 1996). _ in germany (evaluation of methodologies..., 2012) landscape (visual) plans are prepared, which ensure protection of landscape identity, diversity and beauty; visual impact is assessed by specifying quantitative and qualitative indicators of it (colours, textures, visual relations, diversity, uniqueness, scale, proportions, openness of spaces, types, domination of components, etc.). _ in new zealand (evaluation of methodologies..., 2012) the assessment has common ground with the united kingdom method in its emphasis on landscape character. the physical, environmental, and visual attributes of the landscape, such as landform and land cover, combine with aesthetic elements to create the character or sense of place of an area or location. physical, ecological and aesthetic landscape features (terrain, vegetation, buildings, imag51 journal of sustainable architecture and civil engineering 2015/3/12 ery, etc.) determine the protected character of landscape. the main via phases are: establishment of visual character and protected attributes of landscape; evaluation of landscape sensitivity; designation of observation points and observers, photo-fixations; assessment of impact of planned activities on landscape character; designation of areas that require mitigation measures and selection of them. _ in australia methodology of via is also based on united kingdom experience (evaluation of methodologies..., 2012). the guidelines describe eight steps required in carrying via: landscape character analysis based on desk and field study and incorporating the main physical, natural, and built components of the landscape; identification of landscape character zones if the size or complexity of the project suggests that this is helpful; assessment of landscape character impacts based on the sensitivity of the landscape character zone and the magnitude of the proposal in that zone (sensitivity means how sensitive the character of the zone is to the proposed change, while magnitude refers to the nature of the project and the size of the change); assessment of the visibility of the proposal by producing a visual envelope map, primarily related to land form but noting the obscuring effects of vegetation and buildings where possible; identification of key viewpoints within reasonable distance (unspecified) of the project, and within the visual envelope; assessment of visual impacts by combining judgments about the sensitivity of the view with the magnitude of the proposed project in that view; refinement of the concept design to avoid and minimize impacts at an early stage of selecting options and exploring concepts design; development of a mitigation strategy to minimize landscape character and visual impacts with mitigation measures that are integrated with the overall design of the project. _ typical components of via in south african republic are (guidelines for..., 2005): identification of issues and values relating to visual, aesthetic and scenic resources through involvement of specialists and the public; identification of landscape types, landscape character and sense of place, generally based on geology, landforms, vegetation cover and land use patterns; identification of viewsheds, view catchment area and the zone of visual influence, generally based on topography; identification of important view points and view corridors within the affected environment, including sensitive receptors; indication of distance radii from the proposed project to the various view points and receptors; determination of the visual absorption capacity (vac) of the landscape, usually based on topography, vegetation cover or urban fabric in the area; determination of the relative visibility, or visual intrusion, of the proposed project; determination of the relative compatibility or conflict of the project with the surroundings; a comparison of the existing situation with the probable effect of the proposed project, through visual simulation, generally using photo-montages. visual sensitivity of the area is understood as the inherent visibility of the landscape, usually determined by a combination of topography, landform, vegetation cover and settlement pattern. visual absorption capacity (vac) is determined as the potential of the landscape to conceal the proposed project. in other sources of information visual pollution is determined as the phenomenon that causes damage in the sense of beauty and the breakdown of aesthetic considerations and satisfaction and acceptance of the image of the ugly (mohamed et al, 2011); that makes some negative changes in the natural environment and, in this way, turns the visual areas into something that disturbs people (yilmaz et al, 2011; nagle, 2009). magnitude of visual pollution depends on the number of affected persons, on the distance between them and the observed object, and also depends on the orography of the terrain between the observation point and the observed object (garcia-garrido et al). the objects of visual pollution can be: structures, objects of transport infrastructure, garbage containers, electrical infrastructure, the area damaged by mineral extraction, cell phone towers, lighting, outdoor advertisement, neglected greenery, etc. (visual pollution..., 2007; molnár...; mohamed et al, 2011; atta, 2013; yilmaz et al, 2011; nagle, 2009). journal of sustainable architecture and civil engineering 2015/3/12 52 to sum up the experience of foreign countries in the field of via, it can be said that these countries, unlike lithuania, have validated concepts of landscape visual quality and planned activity or object visual impact assessment; systemic and objective methodological recommendations of visual impact assessment, which are used in practical activities of planning and design (table 1). works of lithuanian scientists in lithuania theoretical field of landscape visual quality analysis and evaluation is quite broad and developed. many scientists worked creating methodology of landscape visual quality analysis and evaluating it: k. ėringis ir a. r. budriūnas (1975, 2000), m. purvinas (1975, 1983a, 1983b, 1990), v. stauskas (1966, 2001), p. kavaliauskas (1970, 1992, 2006, 2011, 2015), g. j. daniulaitis (1970), j. bučas (2001), j. kamičaitytė-virbašienė (2003), j. abromas (2014), etc. the most objective and holistic conception of visual pollution is proposed by p. kavaliauskas (2011), r. pakalnis and z. venckus (2012). they state that visual pollution is the loss of aesthetic quality of landscape visual structure caused by irrational human activity. p. kavaliauskas (2011) also defines the notion of landscape visual resistance. it is the ability of landscape structure to absorb new anthropogenic objects in its visual structure without changing the existing invariant type. this concept is synonymous to the notion of landscape visual absorption capacity – a term used in foreign countries via methodologies (guidelines..., 2005; kamičaitytė – virbašienė, 2003; evaluation of methodologies..., 2012). the most important methodical works from the point of view of assessment of visual pollution are methods of quantitative and comparative structural analysis developed by m. purvinas (1975, 1983a, 1990), j. kamičaitytė-virbašienė (2003), p. kavaliauskas (2011), r. skorupskas and v. vasilevskaja (2014) and j. abromas (2014). method of landscape psychological-aesthetic potential analysis (structural analysis) developed by martynas purvinas is the most suitable for territory plans the scale of which is 1:500 1: 10 000. landscape is described by model which consists of visual spaces of various sizes and visual importance marked on topographic plan (purvinas, 1983a). procedural steps of landscape visual analysis (purvinas, 1975) are: designation of landscape visual spaces (vs) as landscape primary structural elements; establishment of vs characteristics (size, configuration, vertical and horizontal closure, visual relations, integrity); establishment of vs naturalness and variety; evaluation of psychological-aesthetical potential of the analysed area (attractive and unlikely objects aesthetically, dominant and background objects are marked); establishment of vs individual characteristics and expert evaluation (by method of overall impression). methodical principles of psychological-aesthetical potential evaluation are applicable to analysis of visual contrast in terms of the planned activity or object visual impact assessment on the environment. after visibility analysis of the object, it is proposed to assess the visual impact (positive or negative contrast of the planned object with the environment, contrast level) according the ratio of object and environmental visual characteristics: size, form, color, tone, facture, and texture (purvinas, 1990). paulius kavaliauskas (2011) also states that the analysis of landscape visual quality should start from the designation of video-tops as visual spaces perceived as integral units from any point inside of them. the criteria of evaluation of landscape aesthetic potential are vitality (indicators are naturalness and wholesomeness), expressivity of landscape structure (indicator is the number of video-tops ranks), individuality (indicators are representativity and originality), and compositional harmony (indicators are formal compositional factors). visual resistance of vs is analysed according the following indicators of vs: plan configuration, size and visibility. ričardas skorupskas and violeta vasilevskaja (2014) developing structural comparative trend of landscape visual research performed analysis of natural landscape colors and forms perception. this work revealed the main factors, which are influencing the perception of the landscape. it is evident that the subject of the appraisal is extremely complicated because it embraces subjective judgement and objective indicators of landscape. 53 journal of sustainable architecture and civil engineering 2015/3/12 jūratė kamičaitytė-virbašienė (2003) proposed the main theoretical methodological steps of via. the whole process of visual impact assessment of planned activity (development) has to be performed as follows: establishment of the quality indicators of the standard (protective) visual type of landscape (determining characteristics of visual spaces, proportions of opened and developed areas, principles of the layout of buildings and greenery, possible visual contextuality of buildings); establishment of the present visual character of landscape and comparison with the standard indicators of landscape visual quality; formation of the target spatial model of landscape (preparation of the conception of landscape formation) the visual indicators of which have to meet the criterions of vitality, complexity, harmony, expressivity, uniqueness, functionality and meaningfulness; after characterizing physical and visual features of the designed structure the possible changes of landscape visual character have to be established and evaluated from the spatial (typical viewing places and visual spaces, zones of visual influence), quantitative (levels of identity indexes of physical and visual characteristics of the structure) and qualitative (character of contextuality of the structure) point of view; in the stage of elaboration the proposals of improvement of visual relation between the designed structure and the contextual landscape have to be prepared according the visual influence of the structure on the main landscape components and overall scenery. jonas abromas (2014) conducted feasibility study of wind turbines visual impact assessment on landscape. his proposed methodology of visual impact assessment consists of: cameral research (project descriptions, establishment of wind turbines visual impact zones, landscape character and visual sensitivity analysis, etc.); research in situ (description of observation points, photo-montages, photo-fixation, assessment of nature, significance and degree of visual impact, etc.); cameral research (public integration, selection of measures of impact mitigation, etc.). summarizing it can be said that methodologies used by lithuanian authors are well developed theoretically and intended for the overall evaluation of landscape visual quality or via, designation of landscape visual quality classes, evaluation of vs indicators, establishment of vs visual resistance and sensitivity. parts of some works can be used for the creation of methodology of visual pollution (negative visual impact) assessment (table 1). table 1 evaluation of theoreticalmethodological framework relevance for visual pollution assessment country/author methodological aspects applicable for the creation of methodology of visual pollution assessment to natural landscape complexes and objects united states the main steps in the contrast rating process; description of the basic design elements; levels of visual contrast united kingdom the main stages of visual impact assessment; notions of visual impact and its significance spain notions of landscape visual sensitivity and capacity; the main steps of via germany quantitative and qualitative indicators of visual impact new zealand notions of landscape character and visual capacity; the main via phases australia steps required in carrying via south african republic typical components of via and notion of vac and visual sensitivity of the area martynas purvinas methodical principles of psychological-aesthetical potential evaluation paulius kavaliauskas criteria and indicators of landscape aesthetic potential and visual resistance of vs jūratė kamičaitytėvirbašienė theoretical methodological steps of via ričardas skorupskas and violeta vasilevskaja methodological issues of visual attributes (colours and forms) perception analysis jonas abromas proposed via stages and their content journal of sustainable architecture and civil engineering 2015/3/12 54 in order to prepare methodology of the assessment of visual pollution to natural landscape complexes and objects legal framework (international and national level) and theoretical framework (world-wide and lithuanian experience in the field of via and assessment of landscape visual-aesthetic potential) was analysed and evaluated. the analysis results of legal framework show that national legislation declares landscape visual-aesthetic potential as national asset and defends ability to admire visually valuable areas and objects; partly regulates the development of the landscape informational field, architectural compositional form; indicates the cases in which eia process has to be applied and specifies harmful impact on landscape (prohibited activities) indirectly noting these activities and their material shape as visual pollution; formulates the need for visual impact assessment, preparation of aesthetical and recreational resources assessment schemes, requires the avoidance of visual pollution, but there are no recommendations how to assess visual impact. the analysis of experience of foreign countries in the field of via, shows that these countries have validated concepts of landscape visual quality and planned activity or object visual impact assessment; systemic and objective methodological recommendations of visual impact assessment, which are used in practical activities of planning and design. methodologies used by lithuanian authors are well developed theoretically and intended for the overall evaluation of landscape visual quality or via, designation of landscape visual quality classes, evaluation of visual spaces indicators, establishment of visual spaces visual resistance and sensitivity. considering the analysis results it is possible to state that the assessment of visual pollution should be based on: the evaluation of visual resources and landscape character, landscape visual capacity (or sensitivity), and other aspects as the starting point for the evaluation of visual pollution; designation of observation points, photo-fixations and 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interests]. kultūrinių kraštovaizdžių apskaita ir apsauga: konferencijos pranešimų medžiaga. kaunas, 2001, p. 13 – 17. turner t. landscape planning and environmental impact design. london, 2003. vasilevskaja v., skorupskas r. esminiai kraštovaizdžio vizualinės struktūros vertinimo aspektai [essential aspects of landscape visual structure assessment]. geografija, 2014, 50(1): 11–22. http://dx.doi. org/10.6001/geografija.v50i1.2889 visual pollution – more dangerous than you think it is. 2007. available at: http://cpreec.org/161.htm (accessed 10 july 2015). visual resource management: information document. washington: bureau of land management. 2001. available at: www.blm.gov (accessed 2 july 2015). yilmaz d., sagsöz a. in the context of visual pollution: effects to trabzon city center silhoutte. asian social science, 2011, 7(5): 98–109. http://dx.doi. org/10.5539/ass.v7n5p98 jūratė kamičaitytė-virbašienė professor kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research area landscape visual quality analysis, evaluation and regulation, methods of planned activity or object visual impact assessment, analysis of social preferences evaluating landscape visual quality and use of the analysis results in territory planning, evaluation of the potential of urban structures, expression of sustainable development conception in architecture, landscape architecture, town and territory planning. address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 61477082 e-mail: jurate.kamicaityte@ktu.lt giedrė godienė doctor, freelanced landscape expert lithuanian geographical society, board member main research area landscape impact assessment, visual impact assessment, studies on landscape legislative system regarding the implementation of european landscape convention, methods and techniques of the public participation, involvement into decision making regarding the landscape issues. address a. baranausko st. 8, lt-04224 vilnius, lithuania tel. +370 68563451 e-mail: g.godiene@gmail.com about the authors 29 journal of sustainable architecture and civil engineering 2017/2/19 *corresponding author: geneatas@yahoo.com incremental construction for sustainable low-income housing delivery in developing countries: a case study of bayelsa state nigeria received 2017/01/14 accepted after revision 2017/06/12 incremental construction for sustainable low-income housing delivery in developing countries: a case study of bayelsa state nigeria jsace 2/19 http://dx.doi.org/10.5755/j01.sace.19.2.17349 eugene ehimatie atamewan* cross river university of technology, department of architecture, calabar, nigeria remi ebenezer olagunju federal university of technology, school of environmental technology, department of architecture, minna, nigeria journal of sustainable architecture and civil engineering vol. 2 / no. 19 / 2017 pp. 29-39 doi 10.5755/j01.sace.19.2.17349 © kaunas university of technology introduction this paper focused on the role of the low-income urban dwellers in attempting to solve their ever increasing and complicated housing problem which is a bye product of the enabling concept. hence, this study was carried out with the main aim of determining the housing type and construction method suitable for the low-income urban dwellers in bayelsa state nigeria. this was achieved through appraisal of the physical characteristics of residential buildings occupied by the low-income earners in the study area. this will help to reduce the growth of urban sprawl in the city and reduce the housing deficit for the urban poor. the study employed mixed method approach of qualitative and quantitative with the former taken most of the study. data were collected by in-depth interview, observation, and questionnaire administration using data presentation instruments (sketches and photographs) to enhance the data presentation. content analysis was used to analyze the qualitative data, while the quantitative data collected was analyzed with both descriptive and inferential statistics. the findings revealed that the housing type suitable for the lowincome is the non-conventional indigenous housing and development method of incremental housing construction. the recommendations included the adoption of incremental housing construction option, simple and less complicated building that satisfies the individual’s spatial preferences and based on the principle of self-help construction and affordability as well as use of local construction methods. keywords: affordability, bayelsa state, incremental housing, low-income, sustainability. governments of developing countries including nigeria over the years and at various times have continuously embarked on some level of interventions in terms of policies, programs and implementation aimed at addressing the housing needs of their citizenry especially the low-income earners who form the bulk of the various urban populations. although these interventions have not been substantially felt by the masses due to the enormous nature and magnitude of the housing problem, suffice to say that some of these actions have ameliorated the housing deficiencies to some extent. nigeria’s housing deficit is currently about 1.7million housing units as at 2010 (finmark, 2010). therefore, it has become very indispensable more than ever before for the public sector to be more proactive in tackling the housing problems. this is due to the importance of housing to the wellbeing, journal of sustainable architecture and civil engineering 2017/2/19 30 social inclusion, and productivity level of the citizenry as well as the wealth of the nation. housing, being a right of every one in any country, the responsibility of the government in providing adequate housing stocks qualitatively and quantitatively for the citizens must be fully discharged. according to jiboye (2011a), the inconsequential attainment recorded the by the nigerian government in the provision of few housing stocks is not commensurate with the yearly budgetary allocation to the housing sector as most nigerians remain increasingly homeless. this goes to show that the public sector housing intervention in nigeria has been more of policy formulation than implementation and housing delivery. undoubtedly, the planning and implementations of the housing intervention programs in nigeria has suffered from governments inconsistencies in policy formulation and weak managerial structure mainly due to centralization mechanism of decision making, execution as well as unwillingness of incumbent government to continue with good policies of the preceding governments (jiboye, 2011b). thus, there is the dire need to introduce a revolutionary change in the housing policies that will include full participation and involvement of all stakeholders namely the public, private sectors, donor agencies and the low-income individuals who are the direct beneficiaries of the product. nonetheless, it is pertinent to emphasize here that the major obstacle to housing ownership in nigeria and other developing countries is affordability problem. this is compounded by high cost of building materials, land acquisition, inadequate housing finance and unrealistic housing standards (atamewan and tabuko, 2016). one major solution is the introduction of incremental housing techniques otherwise known as “low and upgradable” or “build as you earn” on self-help basis which is the focus of this article. incremental housing construction method has as one of its advantage the opportunity of owing and living in one’s house even when the building is not completed or still under construction. in other words, the housing construction is divided into different phases and the owner moves in as soon as one phase is completed. this process promotes housing delivery, reduces homelessness and enhances housing sustainability. low income housing is housing whose occupancy is reserved exclusively for those families or persons that are poor and cannot afford luxurious apartment because their income level is low. it is also defined as housing scheme whereby 20 to 40 % of the buildings units lease controlled and reside by individuals who earn very meagre wages (evans and evans, 2007). the name implies the buildings designed, constructed and intentioned for low-income populace who are in majority. it does not refer to low quality houses but healthy houses with good standards and at reasonably low costs (jinadu, 2007). however, jinadu (2007) observed that the reality in nigeria is that housing units produced under this scheme are often not accessible and affordable to the low-income groups due to stiff competition for the available houses among the low, medium and high income groups. although low income housing is often linked with high crime rate due to the large population it attracts, the benefit of providing appropriate and cheap shelter for most individuals who would have been homeless outweighs this shortcoming. housing provision in nigerian cities including bayelsa urban centres is largely dominated by private ownership which accounts for over 90%. in developed entrepreneur nations, private building corporations are a key provider of housing unlike, nigeria where dwelling units are largely produced by individuals and households (ogu, 1996). it should be noted that housing solution through housing development and provisions would be hampered or inhibited by standards, policies and regulations that are unfavourable to the private individuals and sectors due to the high percentage of privately-constructed houses. survey has showed that over 70% of households in cities are low income and earns ₦216,000 per annum (based on national minimum wages of ₦18,000) or less, ₦70,000 (by definition of low income in nigeria) and presently more than 90% of nigerians who are the low-income find it 31 journal of sustainable architecture and civil engineering 2017/2/19 extremely difficult to own standard housing with all their earnings put together for a period of ten years (fgn, 2006; awofeso, 2010). the implication is that the poor could only wish to own a house built at once to meet minimum standard and regulations. in most developing countries, housing policies and practice does not consider the needs and right of the urban poor, hence the resultant effect of increased housing deficit, sub-standard and illegal settlement which is the only alternative left for the poor to have a roof over their heads (gattoni, 2009). studies (ayoola and amole, 2014) showed that the low-income group has preference for single bungalow building with many rooms, with service facilities such as bathrooms, toilets and cooking area located within or outside and at the back of the house. this implies that the housing type suitable and acceptable by the low-income urban dwellers is that whose design and construction is not expensive and sophisticated to build or maintain. for sustainability of housing delivery, the design standards should be flexible, taking into account the changing needs of the users. the design process must be managed to strike a balance between the income level of the people and the option of standardized housing. a good housing development strategy should provide housing types choices for different income groups and encourage communal integration, promote cultural identities and lifestyle of the people. on the use of building materials, the low-income prefers to use locally sourced traditional materials such as earth (mud). several low-income studies by different researchers (owoeye and amole, 2012; olotuah and taiwo, 2013; ayoola and amole, 2014) found out that the low-income groups preferred to build with mud. most time, the finish is done with sand-cement mortar and sometimes painted to look “modern”. the preference for earth as a building material may be due to the fact that it is an indigenous material that has been used for building construction in nigeria for some centuries. also, earth is seen to be suitable for building in the tropical region like nigeria in addition to cost effectiveness and availability (olotuah and taiwo, 2013). according to finmark (2010), the poor economic backgrounds of the low-income urban dwellers and their inability to access housing finance, has therefore necessitated the low-income urban dwellers in bayelsa state to build their houses on incremental basis with duration of completion taking up to ten years. all over the world, urbanization is a process and it is a common practice for cities to grow and expand and improve basic facilities as population increases. in the same vein, the low-income population in urban centres build houses according to their ability beginning with a room (gattoni, 2009). therefore, housing design standards should be flexible to allow for incremental housing construction, which is affordable and satisfies the socio-economic needs of the urban poor, at the same time reducing future cost and enhance land efficiency. incremental housing, also called core housing simply refers to a small unit or permanent structure that is incomplete with minimum livable space and facilities designed to be upgraded over time (ikaputra 2008; pandelaki and shiozaki, 2010). it starts with a starter core shelter which may be a multi-purpose room with basic kitchen/bath facilities in which case the owners control the expansion based on needs and resources (goethert, 2010). accordingly, incremental housing must have the characteristics which include elements of self-build, improvement and end-user driven, which means the low-income owners must fully participate in all aspects of the construction. pandelaki and shiozaki (2010) summarized the features of incremental housing as follows: a. the building should be planned to have the basic adequate functional space for the needed future expansion. b. the construction of the building is not expected to be completely on self-help basis. c. the primary purpose and condition for the incremental housing construction should be home ownership so as to encourage the required funds and labour for the phased extension. journal of sustainable architecture and civil engineering 2017/2/19 32 d. the building should be constructed with cheap, dismountable and re-usable materials for easy expansion without wasting funds resource. e. the incremental based house is expected to fit in to the local environmental conditions of the area. f. the plot of land should be well-organized in order to accommodate the phased expansions as the need arises. this study employs the mixed-method approach (qualitative and quantitative). this is because of the advantages of greater confidence and provision of checks against the weak points of each approach obtainable with combined methods (groat, 2002; creswell, 2003). but the study is more of qualitative approach. the quantitative data provided this study with essential basic statistics, while qualitative data enriched the research discussion developing a better context for interpreting the results from statistical data. the mixed method involves two phases of data collection and analysis. first, qualitative data was collected and analyzed, then followed by quantitative data collection and analysis. thus, the quantitative data and results helped to interpret the qualitative findings (creswell and plano-clark, 2007). therefore, the study began with qualitative approach with conduct of open-ended interviews to collect detailed views from sampled respondents and proceeded with quantitative approach with a large survey to be able to generalize results to a larger population. the data collected from the field were analysed using content analysis since the research method was majorly qualitative. content analysis was carried out by critically analyzing the information collected from the respondents and the observation notes taken by the researcher during the field work. thus, the main themes that formed the hub of the field work were identified (kumar, 2011). also, the analysis was done following the laid down format and procedures by combining two of the three ways used in communicating findings in qualitative research. the adopted ways were: first was to identify the main subject both from the observation notes and the interview responds from the field work; then translate them sometimes using the exact words of the respondent to emphasize their points. secondly, the main themes from the field work were quantified so as to give their occurrence and thus importance. quantitatively, about 1400 questionnaires were distributed to the low-income respondents across low-income residential neighbourhoods in yenagoa, the state capital of bayelsa state, nigeria. the distribution and return of the questionnaires were made possible with the help of trained research assistants from the study areas who had to administer the questionnaires to the respondents and even translating in local dialect for those who could not understand the questions. the retrieved questionnaires were analyzed using descriptive statistics with the results presented in charts and tables. methodology results this section analyses the personal information and socio-economic characteristics of the respondents (household heads) in the housing units selected from the low-income residential neighfig. 1 sex of respondents in the study areas. source: author survey (2016) 72.50% male 27.50% female sex of respondents bourhoods of the study areas of ogbia, sagbama and yenagoa. these include their gender, age, marital status, nature of employment, income level, status and length of occupancy, number of rooms, number per household, and affordability level of the housing units among others. gender of the respondents. gender of the respondents indicate 72.5% male and 27.5% female revealing that a total of 864 males to 430 females. the study indicates the predominance of male household heads over the females which is in line with 33 journal of sustainable architecture and civil engineering 2017/2/19 fig. 2 respondents nature of employment. source: author survey (2016) 0 100 200 300 400 500 600 700 govt. employed self employed private employment retired 670 333 160 88 table 1 respondents average monthly income. source: author’s survey (2016) percentage (%) frequency 31000 – 50000 naira 36.6% 474 16000 – 30000 naira 24.2% 313 6000 – 15000 naira 22.5% 291 51000 – 70000 naira 11.2% 145 71000 and above 5.5% 71 total 100% 1294 the traditional norms of an average african household where the male folks are regarded as the heads of the family. respondents nature of employment. the survey showed that respondents working with public (government) employment accounts for 51.8% which is the highest. this is followed by those on self-employment accounting for 25.7%. next are those in private employment at 12.4%. respondents who are retired account for 6.8%, while those unemployed stood at 2.5%. respondents average monthly income. table 1 shows that majority of the respondents (36.6%) earns an average monthly income of between ₦31,000 and ₦50 000. the respondents who earn between ₦16 000 and ₦30 000 stood at 24.2%. this was closely followed by respondents who earn between ₦6 000 and ₦15 000 which is 22.5%. those who earn between ₦51 000 and ₦70 000 were put at 11.2%. a small proportion of the respondents (5.5%) earns above ₦71 000. respondents length of occupancy. on the length of occupancy (duration) of the respondents in their respective housing units and the neighbourhood, the results show that a larger proportion (48.3%) had lived in their residence for between 6 and 10 years, while 24.2% of the respondents had lived for a period of 11-20 years. this is followed by 15.3% respondents who had lived for a period of over 20 years. the respondents who had lived in their residence for 2-5 years stood at 10.5% while the lowest percentage of 1.6% had lived for 0-1year as detailed in fig. 3. the study suggests that very high proportion of the respondents had lived reasonable number of years in their various apartments and the neighbourhoods signifying that they are used to the environment and could therefore give useful information relevant to the study. respondents nature of occupancy (ownership). the study shows that a greater percentage of the respondents (64.3%) lives in rented housing units, 28.6% live in owner-occupied housing units while a few percentage of respondents (7.1%) live in family-owned housing units. this suggests that a greater proportion of the low-income urban dwellers are yet to own their houses signijournal of sustainable architecture and civil engineering 2017/2/19 34 fig. 3 respondents length of occupancy. source: author’s survey (2016) 136 625 313 198 0 100 200 300 400 500 600 700 2 5yrs 6 10yrs 11 20yrs over 20yrs 64% 28.60% 7.10% rented housing units owner-occupied housing units fig. 4 respondents nature of occupancy. source: author’s survey (2016) 136 625 313 198 0 100 200 300 400 500 600 700 2 5yrs 6 10yrs 11 20yrs over 20yrs 64% 28.60% 7.10% rented housing units owner-occupied housing units fying that home ownership was still very low in the urban centers of the state and this is in line with previous findings (larenwaju, 2012; ibem, 2011; ogunleye, 2013), which assert that greater proportion of the low-income earners in most cities of developing nations live in rented accommodation. respondents household size. the study shows that 43.7% of respondents claimed that their household size was more than four persons, 26.3% had 4 persons, 15.8% had 3 persons, 11.1% had 2 persons while 2.1% had 1 person. this suggests that there is a predominance of household with more than 4 persons in the 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% more than 4 4 persons 3 persons 2 persons 1 person 43.70% 26.30% 15.80% 11.10% 2.10% study areas; this may be due to the fact that most respondents are married and have children / other dependents living with them. it is pertinent to state that the percentage is highest in yenagoa. this may not be unconnected with the fact that it is the capital city with its attendant problem of high cost of accommodation, high population and high low-income earners. the implication here is that people in the study areas especially yenagoa suffer from high occupancy rate (overcrowding) in which case adults of different sex not married may be living together in the same fig. 5 respondents household size. source: author’s survey (2016) 35 journal of sustainable architecture and civil engineering 2017/2/19 room which in turn promotes immorality, early marriages, increased rate of disease and other social problems. this study agrees with earlier findings of ede et al. (2007) which showed that yenagoa had a high occupancy rate as with many urban centers in nigeria. respondents affordability of the housing units. the respondents were also asked to evaluate the cost of acquiring or renting their housing units. the evaluation indices were from very unaffordable, unaffordable, affordable to very affordable. greater proportion of the respondents 71.4% indicated that cost was unaffordable. this was followed by 13.7% respondents who agreed the cost of housing was very unaffordable, this was closely followed by 14.9% respondents who claimed that the cost of housing was affordable while very affordable had 0% respondent. this is an indication that the low-income urban dwellers and in the study areas see the cost of acquiring and or renting their housing units as generally unaffordable. from the results above, it can be deduced that a higher percentage of the respondents are male (household heads), employed in the public sector and their income level suggests that majority of the respondents are low-income earners. this is not quite surprising as the neighbourhood sampled were already seen to exhibit the characteristics of low-income environment. the results further suggest that greater proportions of the respondents are in privately rented housing units. also, the results revealed that the household size for most of the respondents were large with over six persons per household irrespective of the size of the housing unit. this suggests a high rate of overcrowding in the neighbourhoods. in addition, the results also show that majority of the respondents find the cost of their housing unit very unaffordable. this goes to show that the cost of accommodation is far beyond the reach of the low-income urban dwellers. this may be due to the fact that the there are few housing units(shortage of housing units) compared with the population explosion in the study areas, high cost of building materials, high cost of building construction owing to high cost of lands, land filling due to its swampy nature. housing affordability. most of the respondents interviewed claimed that costs of constructing houses are too expensive. they opined that meeting very essential needs in the family was not easy and therefore the question of standard completed house does not even arise. a respondent queried: “who says my house is not standard. am i complaining? as you can see, i am okay with this house for now. when condition of my pocket improves, the house will imp rove too.” they posited that they can only build what they can afford. some respondents claimed that cost of building material and land for building is beyond their reach. this suggests that housing affordability is still a serious hindrance towards house ownership in this part of the world. housing types and development method suitable for low-income urban dwellers. this study reveals respondents’ preference for a housing proposal that is based on the principle of affordable standards and cultural identity. the respondents asserted that they enjoy building their own houses their own way based on the principle of self-help in which case the buildings must be simple and less sophisticated in construction. the building also should satisfy the individual’s spatial preferences. one respondent said: ”they(government) should allow us to build the kind of house we want, not the type they will tell you to put dining here, room there, no place to feel our kind of culture and free yourself; those kind of houses are for the big men and oyinbo (white) people”. the implication here is that the respondents do not favour the current conventional housing types of either one storey or multi-storey designs with wc and large spaces that are only affordable by a few high income earners in the society because these does not apply to the ways of living of the low-income groups who are in the majority. government and agencies should therefore permit housing types such as tenement (with many rooms) that develops and improves over time with outdoor sanitary facilities and kitchen which are suitable and affordable since they suit the ways of living of the low-income households. the study showed that the most respondents prefer to build their houses on incremental level, that is, step by step method. this is also called starter house, phased-development or core housing which is discussion journal of sustainable architecture and civil engineering 2017/2/19 36 a step-by-step housing construction method which is an integral urban development process. most of the respondents posited that it was unfair to compel everybody to follow one pattern of housing standard claiming that “all fingers are not the same, so the government should know that not everybody can afford to build their house at once”. incremental housing construction is an affordable and flexible way by which low-income households can own their houses gradually since they cannot afford to build their houses instantly. professionals have argued that building types that are practicable for low-income households are those that can be extendable over time as the owner wishes. this implies that the best housing construction option for the low-income household is the “house that develops or extends as the income of the owner improves”, which means that one first constructs a room or two rooms and occupies the house before it is fully completed (nnaggenda-musana, 2008). the study also showed that conventional house type that the current building regulations and standards support is foreign building materials. most respondents claimed that these preferred materials are very expensive. they opined that in the past centuries, virtually every adult family male could afford to build his house because the building materials were locally sourced. the preference of modern or foreign building materials over the local/traditional materials found almost in every area of the country is an indication that people in this part of the world do not value their own nature-given resources. hence, the researcher is advocating the use of earth and its associated products (bricks, stabilized earth) for low-income housing construction. the implication here is that housing deficit will be on the increase instead of decreasing because imported building materials are very expensive and make housing construction unaffordable to the low-income urban dwellers. this study also shows that most of the low-income households make use of outdoor spaces (fig. 7, 8). the outdoor spaces in the low-income neighborhoods of bayelsa state accommodate the sanitary facilities such as toilets and bathrooms. the study revealed that sanitary facilities in the neighbourhood are usually shared by different households of the same building or sometimes of different buildings and are located separately from the main house(s). this reasons given by respondents showed that the low-income urban households cannot afford or maintain waterborne toilets individually simply because there is no money or potable water supply in their neighbourhoods. as one respondent queried: “we don’t even have water to drink or cook, then who is talking about water for flushing toilets”. also, where an individual household can manage to have a waterborne toilet, it is being shared amongst members of the same household. on the other hand, kitchens have been seen in this study to be either detached from or attached to the main housing units as another outdoor space (fig. 7, 8). the respondents claimed that this has been the way of living by majority of the low-income urban dwellers and it should be encouraged fig. 7 floor plan of building with attached kitchen and toilet/bath 37 journal of sustainable architecture and civil engineering 2017/2/19 fig. 8 floor plan of building with detached toilet/ bath by professionals, agencies and government. one respondent just laughed and said, “these people, so they want us to cook inside the house with firewood when they know that we cannot buy gas or kerosene to cook our food. we use firewood and saw dust and we don’t want smoke inside the house.” the implication therefore is that in the design of low-income houses, the local conditions and ways of living of the residents including the extensive provision of outdoor spaces for interactions, socialization and other outdoor activities should be considered while also improving their housing standards. the study has revealed that self-help and incremental construction methods were the choice of the low-income urban dwellers in bayelsa state. thus they prefer to begin with a starter unit and progresses as income flows in. it was also discovered that the low-income urban dwellers in bayelsa state had preference for local indigenous building materials as against the convectional building materials which they claimed were unaffordable. most of the low-income had preference for an indigenous housing type where some of the services spaces (especially kitchen, toilet and bath place) are either attached or detached completely from the main building (fig. 7, 8). furthermore, it was revealed that the low-income neighbourhood in bayelsa urban centers lacked access to housing fund due to inadequate collateral security as requirement for accessing such housing finance; therefore, they relied on personal savings to carry out housing construction. the study recommends as follows: 1 incremental design and construction. low-income households should be allowed to build and own their houses gradually since they cannot afford to build their houses instantly. this method provides secure title, affordability and maximum flexibility in housing decisions. 2 this study recommends a new housing proposal that is based on the principle of afford-able standards and cultural identity. simple and less complicated building that satisfies the individual’s spatial preferences and based on the principle of self-help construction should be encouraged and permitted. with outdoor sanitary facilities and kitchen as against the preference for the conventional housing types as in fig. 8. 3 in the design of low-income houses, the local conditions and ways of living of the residents including the location of some functional and service spaces outside the main housing unit should be considered while at the same time improving their housing standards. 4 use of local building materials. the study recommends that the use of local/traditional materials should be promoted. this is because apart from the cost effectiveness, they are suitable to the local climatic conditions and are easy to maintain too. conclusions journal of sustainable architecture and civil engineering 2017/2/19 38 atamewan, e. e and tabuko, b (2016). infrastructure development and financing for sustainable housing delivery in nigeria: a review. sustainable built environment and climate change; the challenges of post 2015 development agenda. school of 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(2010). one out of two nigerians now lives in a city: there are many problems but one solution. world policy journal, 27:67. https://doi. org/10.1162/wopj.2011.27.4.67 ayoola a., amole d. (2014). the value of housing among the poor in ilesa, osun state nigeria; architecture research; 4(1a), 45-54 bayelsa state ministry of information, culture and tourism (bmict), 2002. history of bayelsa state: people, culture and economy. yenagoa: bmict press. creswell, j. w (2003). research design: qualitative, quantitative and mixed methods approaches. thousand oaks, california. 2nd edition sage publications inc; 1-26 creswell, j. w., plano-clark. v. l. (2007). designing and conducting mixed methods research. thousand oaks. ca; sage publications inc. ede, p.n, ebakpa, a.f., chukuigwe, e.c. (2007). determination of housing and neighbourhood quality for yenagoa, bayelsa state of nigeria: journal of the nigerian institute of town planners. 20 (16), 99-118 evans, d.l, evans, w.o. (2007). the complete real estate encyclopaedia. london: the mcgraw-hill companies inc. federal government of nigeria, fgn (2006). national building code. federal ministry of housing and urban development, abuja. finmark trust (2010). overview of the housing finance sector in nigeria. centre for affordable housing finance in africa, working paper 12: uk dfid; bill and melinda gates foundation 12(1), 1-52 gattoni , g.(2009). a case for the incremental housing process in sites-and-services. programmes and comments on a new initiative in guyana. inter-american development bank; 2 (18) goethert, r (2010). incremental housing. a proactive urban strategy. incremental housing bulletin: september. groat, l. (2002). case studies and combined strategies in architectural research methods, canada: john wiley & sons, inc. 341-373. ibem, e. o. (2011). evaluation of public housing in ogun state, nigeria, unpublished phd thesis of the references department of architecture, covenant university, ota, ogun state, nigeria. ikaputra (2008). people response to localize the imported culture. study case: the dome jinadu, a.m. (2007). understanding the basics of housing. jos: jos university press ltd. jiboye, a.d (2011a). urbanization challenges and housing delivery in nigeria: the need for an effective policy framework for sustainable development: international review of social sciences and humanities: 2 (1), 20-29 jiboye, a. d. (2011c) ensuring sustainable development through an effective housing delivery process in nigeria. african journal of social sciences. 1 (2), 36-45. kumar, r. (2011). research methodology: a stepby-step guide for beginners. london, sage publications ltd. lanrewaju, a.f. (2012). housing quality in informal settlements and urban upgrading in ibadan, nigeria: developing country studies. 2 (10). nnaggenda-musana, a. m. (2008). housing clusters for densification within an upgrading strategy, the case of kampala, uganda. unpublished doctoral dissertation royal institute of technology & makerere university stockholm and kampala. ogu, v.i. (1996). housing and environmental services in benin city, nigeria. unpublished doctoral dissertation, university of cambridge, england. ogunleye, b. m. (2013): analysis of the socio-economic characteristics and housing condition in the core neighbourhood of akure, nigeria. journal of geography and regional planning.6 (6), 229-236. https://doi.org/10.5897/jgrp2013.0383 owoeye, j.o & omole, f.k (2012). analysis of housing condition and neighbourhood quality of residential core of akure, nigeria. mediterranean journal of social sciences. 1. (3), 471 olotuah, a. o. and taiwo, a. a. (2013). housing the urban poor in nigeria through low-cost housing schemes. international journal of physical and human geography 1 (3),1-8 pandelaki e. e. and shiozaki y. (2010).the core house concept and its implementation in indonesia: past, present, future. international journal for housing science, 34 (4), 233-248. undp (1997). governance for sustainable human development. new york. united nations development programme. 39 journal of sustainable architecture and civil engineering 2017/2/19 eugene ehimatie atamewan lecturer cross river university of technology, department of architecture main research area sustainable housing and building maintenance & management address cross river university of technology, department of architecture, calabar, nigeria e-mail: geneatas@yahoo.com about the authors remi ebenezer olagunju assoc. professor department of architecture, school of environmental technology main research area sustainable housing and building maintenance & management address federal university of technology, minna, nigeria tel: +2347065003865 e-mail: olagunju@futminna.edu.ng journal of sustainable architecture and civil engineering 2018/1/22 88 *corresponding author: deividas.martinavicius@ktu.edu experimental and numerical investigation of concrete filled closed section steel beams received 2018/04/30 accepted after revision 2018/07/05 journal of sustainable architecture and civil engineering vol. 1 / no. 22 / 2018 pp. 88-98 doi 10.5755/j01.sace.22.1.20862 © kaunas university of technology experimental and numerical investigation of concrete filled closed section steel beams jsace 1/22 http://dx.doi.org/10.5755/j01.sace.22.1.20862 deividas martinavičius*, mindaugas augonis, nerijus adamukaitis, tadas zingaila civil engineering and architecture competence centre, faculty of civil engineering and architecture, kaunas university of technology, studentu st. 48, lt-51367 kaunas, lithuania introduction the aim of this paper is to investigate closed section steel and composite beams. composite beams usually possess an increased stiffness compared to the regular steel profiles. as a consequence, vibrations of the composite beams are lower. what is more, composite beams have a relatively high fire resistance. in many cases, this kind of beams can be used without additional fire protection. furthermore, when the concrete in the composite beam is compressed, it becomes confined by the steel profile. confined concrete possesses a more favourable behaviour. it becomes more ductile and can reach a relatively high compressive strength. all those qualities make the usage of the composite constructions beneficial and effective. however, the theoretical evaluation of the composite beam resistance becomes complicated as there are many different models for the confined concrete. another problem is contact between steel and concrete. it can be evaluated as a friction between different materials or a stiff connection between surfaces. in this research, experimental tests are carried out. two steel and two composite beams are tested under bending. load-displacement curves are obtained. mechanical properties of the concrete are investigated. experimental results of the beam bending are compared to those obtained by the finite element analysis. material model of the concrete confined by the steel profile is used in the analysis. the similar finite element analysis is later carried out to investigate the beams of another author. the validity of theoretical models is investigated. keywords: composite beam, confined concrete, buckling, finite element analysis. composite steel-concrete beams are becoming more and more popular. this kind of beams combine beneficial properties. they possess a high fire resistance, stiffness and lower natural frequencies than regular steel beams. furthermore, composite beams are not as massive as regular reinforced concrete beams and the steel profile can be used as a formwork for concrete. however, evaluation of the resistance of the composite beam is more complex. to understand the behaviour of composite beams different authors have carried out experiments. hassanein et. al. (2017) has done bending experiments for thin walled closed section rectangular composite beams filled with two types of concrete: regular concrete c80 and glass-fibre reinforced cementitious material fc55 and fc60. it was found that the strains in the steel profile filled with cementitious material were higher than the strains in the profile filled with regular concrete. what is more, the cracking started at the higher load. it was also found that regular concrete filled 89 journal of sustainable architecture and civil engineering 2018/1/22 beams had a lower toughness and were able to absorb less energy than beams filled with cementitious material. soundararajan and shanmugasundaram (2008) have done a similar experimental research on closed section steel beams filled with different types of concrete: normal mix concrete (nmc), fly ash concrete (fac), quarry waste concrete (qwc) and low strength concrete (lsc). the authors have found that filling the steel profile with nmc, fac, qwc has increased the resistance of beam by up to 25 % and filling with lsc led to a 16 % higher strength. some authors have combined experimental tests and finite element analysis. lu et. al. (2007) has done a research on non-uni-thickness welded steel beams. the beams consisted of the thicker bottom plate (t2) and thinner top plates and webs (t1). authors have found that the most favourable value of ratio t2/t1 was 1.5-2. by using the thicknesses in this range, the resistance of the composite beam could be increased by up to 5%. the authors have also taken into account that the concrete is confined by the steel profile. confinement model of schneider (1998) was used in the finite element analysis of this research. this model assumes that the concrete ductility is increased, but the compressive strength remains the same as the strength of the non-confined concrete. zhan et. al. (2016) has carried out a research on prestressed concrete-filled steel beams. the author has found that the cracking moment was up to 4 times higher than the moment of the non-prestressed beams. furthermore, it was noted that the prestressed strands increased the effect of confinement significantly. the authors have used the confinement model of tomii and sakino (1979) which is similar to the model of schneider (1998). it was found that the experimental results fit with the results of the finite element analysis if the confined concrete model is used instead of a regular model. considering the regular concrete model the resistance of the beam starts to decrease too early compared to the experimental results. there are more different models to evaluate the confinement of concrete. han (2001) created a model which is not as conservative as the model of tomii and sakino (1979). the author has suggested a confinement factor which depends on the steel yield strength and concrete compressive strength as well as the cross-sectional areas of those elements. this factor is used to find a compressive strength of the confined concrete. han’s model also takes into account an increased ductility of the concrete. to approve the proposed model, han has carried out experiments on the composite beams and columns (2004). huang (2002) has proposed another confinement model. the compressive strength in this model is dependent only on the yield stress of steel and width to thickness ratio of the steel profile. there are also more models which describe the confinement in reinforced concrete columns. hsq (hedlunds svetsade q-balk) beams are usually used to build a slim floor structure (pajari 2010 and bzdawka 2012). this is enabled by the usage of the bottom flange of the beam as a support for the deck slab. however, hsq beams are usually used as a simple steel construction. in order to increase the stiffness and the fire resistance of the hsq beam, it was decided to fill it with concrete. there are several papers that investigate the closed section rectangular composite beams (han 2004, lu et. al. 2007 and hassanein et. al. 2017) or steel hsq beams (pajari 2010 and bzdawka 2012), but in the scope of reviewed papers, there was no information about hsq beams filled with concrete. as a consequence, the research needs to be carried out to evaluate the effect of the infill concrete for the load-deflection behaviour of the hsq beams. experimental methods and specimens four specimens of 1.5 m length beams have been tested under bending during the course of the experimental programme. two beams (n1-s and n2-s) of different cross-sections consisted of welded steel plates. two other beams were identical welded steel profiles as those mentioned before, but were later filled with concrete. the latter specimens n1-c and n2-c are considered composite. cross-sections of specimens are presented in table 1. all the dimensions were approximately two times smaller than the beams usually used for the construction of the buildings. journal of sustainable architecture and civil engineering 2018/1/22 90 it was decided to vary only the height and thickness of the web to obtain the beams having different bending resistances while also avoiding an increased consumption of the materials. table 1 marking and cross section of beam specimens sp ec im en n1-s n2-s n1-c n2-c c ro ss -s ec tio n beam could be increased by up to 5%. the authors have also taken into account that the concrete is confined by the steel profile. confinement model of schneider (1998) was used in the finite element analysis of this research. this model assumes that the concrete ductility is increased, but the compressive strength remains the same as the strength of the non-confined concrete. zhan et. al. (2016) has carried out a research on prestressed concrete-filled steel beams. the author has found that the cracking moment was up to 4 times higher than the moment of the nonprestressed beams. furthermore, it was noted that the prestressed strands increased the effect of confinement significantly. the authors have used the confinement model of tomii and sakino (1979) which is similar to the model of schneider (1998). it was found that the experimental results fit with the results of the finite element analysis if the confined concrete model is used instead of a regular model. considering the regular concrete model the resistance of the beam starts to decrease too early compared to the experimental results. there are more different models to evaluate the confinement of concrete. han (2001) created a model which is not as conservative as the model of tomii and sakino (1979). the author has suggested a confinement factor which depends on the steel yield strength and concrete compressive strength as well as the cross-sectional areas of those elements. this factor is used to find a compressive strength of the confined concrete. han’s model also takes into account an increased ductility of the concrete. to approve the proposed model, han has carried out experiments on the composite beams and columns (2004). huang (2002) has proposed another confinement model. the compressive strength in this model is dependent only on the yield stress of steel and width to thickness ratio of the steel profile. there are also more models which describe the confinement in reinforced concrete columns. hsq (hedlunds svetsade q-balk) beams are usually used to build a slim floor structure (pajari 2010 and bzdawka 2012). this is enabled by the usage of the bottom flange of the beam as a support for the deck slab. however, hsq beams are usually used as a simple steel construction. in order to increase the stiffness and the fire resistance of the hsq beam, it was decided to fill it with concrete. there are several papers that investigate the closed section rectangular composite beams (han 2004, lu et. al. 2007 and hassanein et. al. 2017) or steel hsq beams (pajari 2010 and bzdawka 2012), but in the scope of reviewed papers, there was no information about hsq beams filled with concrete. as a consequence, the research needs to be carried out to evaluate the effect of the infill concrete for the load-deflection behaviour of the hsq beams. experimental methods and specimens four specimens of 1.5 m length beams have been tested under bending during the course of the experimental programme. two beams (n1-s and n2-s) of different cross-sections consisted of welded steel plates. two other beams were identical welded steel profiles as those mentioned before, but were later filled with concrete. the latter specimens n1-c and n2-c are considered composite. cross-sections of specimens are presented in table 1. all the dimensions were approximately two times smaller than the beams usually used for the construction of the buildings. it was decided to vary only the height and thickness of the web to obtain the beams having different bending resistances while also avoiding an increased consumption of the materials. table 1. marking and cross section of beam specimens. specimen n1-s n2-s n1-c n2-c crosssection beam could be increased by up to 5%. the authors have also taken into account that the concrete is confined by the steel profile. confinement model of schneider (1998) was used in the finite element analysis of this research. this model assumes that the concrete ductility is increased, but the compressive strength remains the same as the strength of the non-confined concrete. zhan et. al. (2016) has carried out a research on prestressed concrete-filled steel beams. the author has found that the cracking moment was up to 4 times higher than the moment of the nonprestressed beams. furthermore, it was noted that the prestressed strands increased the effect of confinement significantly. the authors have used the confinement model of tomii and sakino (1979) which is similar to the model of schneider (1998). it was found that the experimental results fit with the results of the finite element analysis if the confined concrete model is used instead of a regular model. considering the regular concrete model the resistance of the beam starts to decrease too early compared to the experimental results. there are more different models to evaluate the confinement of concrete. han (2001) created a model which is not as conservative as the model of tomii and sakino (1979). the author has suggested a confinement factor which depends on the steel yield strength and concrete compressive strength as well as the cross-sectional areas of those elements. this factor is used to find a compressive strength of the confined concrete. han’s model also takes into account an increased ductility of the concrete. to approve the proposed model, han has carried out experiments on the composite beams and columns (2004). huang (2002) has proposed another confinement model. the compressive strength in this model is dependent only on the yield stress of steel and width to thickness ratio of the steel profile. there are also more models which describe the confinement in reinforced concrete columns. hsq (hedlunds svetsade q-balk) beams are usually used to build a slim floor structure (pajari 2010 and bzdawka 2012). this is enabled by the usage of the bottom flange of the beam as a support for the deck slab. however, hsq beams are usually used as a simple steel construction. in order to increase the stiffness and the fire resistance of the hsq beam, it was decided to fill it with concrete. there are several papers that investigate the closed section rectangular composite beams (han 2004, lu et. al. 2007 and hassanein et. al. 2017) or steel hsq beams (pajari 2010 and bzdawka 2012), but in the scope of reviewed papers, there was no information about hsq beams filled with concrete. as a consequence, the research needs to be carried out to evaluate the effect of the infill concrete for the load-deflection behaviour of the hsq beams. experimental methods and specimens four specimens of 1.5 m length beams have been tested under bending during the course of the experimental programme. two beams (n1-s and n2-s) of different cross-sections consisted of welded steel plates. two other beams were identical welded steel profiles as those mentioned before, but were later filled with concrete. the latter specimens n1-c and n2-c are considered composite. cross-sections of specimens are presented in table 1. all the dimensions were approximately two times smaller than the beams usually used for the construction of the buildings. it was decided to vary only the height and thickness of the web to obtain the beams having different bending resistances while also avoiding an increased consumption of the materials. table 1. marking and cross section of beam specimens. specimen n1-s n2-s n1-c n2-c crosssection beam could be increased by up to 5%. the authors have also taken into account that the concrete is confined by the steel profile. confinement model of schneider (1998) was used in the finite element analysis of this research. this model assumes that the concrete ductility is increased, but the compressive strength remains the same as the strength of the non-confined concrete. zhan et. al. (2016) has carried out a research on prestressed concrete-filled steel beams. the author has found that the cracking moment was up to 4 times higher than the moment of the nonprestressed beams. furthermore, it was noted that the prestressed strands increased the effect of confinement significantly. the authors have used the confinement model of tomii and sakino (1979) which is similar to the model of schneider (1998). it was found that the experimental results fit with the results of the finite element analysis if the confined concrete model is used instead of a regular model. considering the regular concrete model the resistance of the beam starts to decrease too early compared to the experimental results. there are more different models to evaluate the confinement of concrete. han (2001) created a model which is not as conservative as the model of tomii and sakino (1979). the author has suggested a confinement factor which depends on the steel yield strength and concrete compressive strength as well as the cross-sectional areas of those elements. this factor is used to find a compressive strength of the confined concrete. han’s model also takes into account an increased ductility of the concrete. to approve the proposed model, han has carried out experiments on the composite beams and columns (2004). huang (2002) has proposed another confinement model. the compressive strength in this model is dependent only on the yield stress of steel and width to thickness ratio of the steel profile. there are also more models which describe the confinement in reinforced concrete columns. hsq (hedlunds svetsade q-balk) beams are usually used to build a slim floor structure (pajari 2010 and bzdawka 2012). this is enabled by the usage of the bottom flange of the beam as a support for the deck slab. however, hsq beams are usually used as a simple steel construction. in order to increase the stiffness and the fire resistance of the hsq beam, it was decided to fill it with concrete. there are several papers that investigate the closed section rectangular composite beams (han 2004, lu et. al. 2007 and hassanein et. al. 2017) or steel hsq beams (pajari 2010 and bzdawka 2012), but in the scope of reviewed papers, there was no information about hsq beams filled with concrete. as a consequence, the research needs to be carried out to evaluate the effect of the infill concrete for the load-deflection behaviour of the hsq beams. experimental methods and specimens four specimens of 1.5 m length beams have been tested under bending during the course of the experimental programme. two beams (n1-s and n2-s) of different cross-sections consisted of welded steel plates. two other beams were identical welded steel profiles as those mentioned before, but were later filled with concrete. the latter specimens n1-c and n2-c are considered composite. cross-sections of specimens are presented in table 1. all the dimensions were approximately two times smaller than the beams usually used for the construction of the buildings. it was decided to vary only the height and thickness of the web to obtain the beams having different bending resistances while also avoiding an increased consumption of the materials. table 1. marking and cross section of beam specimens. specimen n1-s n2-s n1-c n2-c crosssection beam could be increased by up to 5%. the authors have also taken into account that the concrete is confined by the steel profile. confinement model of schneider (1998) was used in the finite element analysis of this research. this model assumes that the concrete ductility is increased, but the compressive strength remains the same as the strength of the non-confined concrete. zhan et. al. (2016) has carried out a research on prestressed concrete-filled steel beams. the author has found that the cracking moment was up to 4 times higher than the moment of the nonprestressed beams. furthermore, it was noted that the prestressed strands increased the effect of confinement significantly. the authors have used the confinement model of tomii and sakino (1979) which is similar to the model of schneider (1998). it was found that the experimental results fit with the results of the finite element analysis if the confined concrete model is used instead of a regular model. considering the regular concrete model the resistance of the beam starts to decrease too early compared to the experimental results. there are more different models to evaluate the confinement of concrete. han (2001) created a model which is not as conservative as the model of tomii and sakino (1979). the author has suggested a confinement factor which depends on the steel yield strength and concrete compressive strength as well as the cross-sectional areas of those elements. this factor is used to find a compressive strength of the confined concrete. han’s model also takes into account an increased ductility of the concrete. to approve the proposed model, han has carried out experiments on the composite beams and columns (2004). huang (2002) has proposed another confinement model. the compressive strength in this model is dependent only on the yield stress of steel and width to thickness ratio of the steel profile. there are also more models which describe the confinement in reinforced concrete columns. hsq (hedlunds svetsade q-balk) beams are usually used to build a slim floor structure (pajari 2010 and bzdawka 2012). this is enabled by the usage of the bottom flange of the beam as a support for the deck slab. however, hsq beams are usually used as a simple steel construction. in order to increase the stiffness and the fire resistance of the hsq beam, it was decided to fill it with concrete. there are several papers that investigate the closed section rectangular composite beams (han 2004, lu et. al. 2007 and hassanein et. al. 2017) or steel hsq beams (pajari 2010 and bzdawka 2012), but in the scope of reviewed papers, there was no information about hsq beams filled with concrete. as a consequence, the research needs to be carried out to evaluate the effect of the infill concrete for the load-deflection behaviour of the hsq beams. experimental methods and specimens four specimens of 1.5 m length beams have been tested under bending during the course of the experimental programme. two beams (n1-s and n2-s) of different cross-sections consisted of welded steel plates. two other beams were identical welded steel profiles as those mentioned before, but were later filled with concrete. the latter specimens n1-c and n2-c are considered composite. cross-sections of specimens are presented in table 1. all the dimensions were approximately two times smaller than the beams usually used for the construction of the buildings. it was decided to vary only the height and thickness of the web to obtain the beams having different bending resistances while also avoiding an increased consumption of the materials. table 1. marking and cross section of beam specimens. specimen n1-s n2-s n1-c n2-c crosssection steel hsq beams were placed vertically and were gradually filled with concrete. the concrete was poured by 3-4 steps and compacted manually by using the steel bar. beam specimens are presented in fig. 1. the concrete specimens were casted fig. 1 steel (left) and composite (right) beam specimen fig. 2 experimental test setup (left) and load scheme (right) steel hsq beams were placed vertically and were gradually filled with concrete. the concrete was poured by 3-4 steps and compacted manually by using the steel bar. beam specimens are presented in fig. 1. the concrete specimens were casted at the same time. all the specimens were covered and left to cure under the laboratory conditions for 28 days. fig. 1. steel (left) and composite (right) beam specimens. nine cubic 100x100x100 specimens were tested under compression to find the compressive strength of the concrete which was used to fill the composite beams. six specimens (100x100x400) were tested under bending using one concentrated force applied at the centre. the bending resistance was later used to calculate the tensile strength of the concrete. four 100x100x300 specimens were also tested to find the elastic modulus of the concrete. toni technik 2020 press was used to test the concrete specimens. the arrangement of the beam bending experiment is presented in fig. 2 (left). the beam was placed on two supports: one hinge and one roller. the load was applied to the balance beam by the hydraulic press. the balance beam distributed the load on two cylinders with the base plates of 50 mm width. positions of supports and loads are presented in fig. 2 (right). fig. 2. experimental test setup (left) and load scheme (right). the 50 tons capacity hydraulic press grm-1 was used to test the beams. the load was applied to the beam by stages. preliminary analytical calculations were made before the start of the experiments to obtain the position of neutral axis and plastic bending resistance of each beam. at each stage the load was increased by approximately 10% of the calculated ultimate load during the period of 60-90 seconds. the displacements were measured by three deflection indicators (located at the supports and the middle of the beam) at each stage. finally, the deflection was calculated by eliminating the deformation of the supports. material properties cubic concrete specimens were tested under compression. the results are presented in the table 2. specimens 1.1c-1.5c are made of the concrete which was used for the composite beam n1-c. the standard deviation and coefficient of variation of the results of this series is 2.43 mpa and 0.0503 respectively. other specimens 2.1c-2.4c are made of the concrete which was used to fill the beam n2-c. the standard deviation and coefficient of variation of the results of this series is 3.4 mpa and 0.0671 respectively. steel hsq beams were placed vertically and were gradually filled with concrete. the concrete was poured by 3-4 steps and compacted manually by using the steel bar. beam specimens are presented in fig. 1. the concrete specimens were casted at the same time. all the specimens were covered and left to cure under the laboratory conditions for 28 days. fig. 1. steel (left) and composite (right) beam specimens. nine cubic 100x100x100 specimens were tested under compression to find the compressive strength of the concrete which was used to fill the composite beams. six specimens (100x100x400) were tested under bending using one concentrated force applied at the centre. the bending resistance was later used to calculate the tensile strength of the concrete. four 100x100x300 specimens were also tested to find the elastic modulus of the concrete. toni technik 2020 press was used to test the concrete specimens. the arrangement of the beam bending experiment is presented in fig. 2 (left). the beam was placed on two supports: one hinge and one roller. the load was applied to the balance beam by the hydraulic press. the balance beam distributed the load on two cylinders with the base plates of 50 mm width. positions of supports and loads are presented in fig. 2 (right). fig. 2. experimental test setup (left) and load scheme (right). the 50 tons capacity hydraulic press grm-1 was used to test the beams. the load was applied to the beam by stages. preliminary analytical calculations were made before the start of the experiments to obtain the position of neutral axis and plastic bending resistance of each beam. at each stage the load was increased by approximately 10% of the calculated ultimate load during the period of 60-90 seconds. the displacements were measured by three deflection indicators (located at the supports and the middle of the beam) at each stage. finally, the deflection was calculated by eliminating the deformation of the supports. material properties cubic concrete specimens were tested under compression. the results are presented in the table 2. specimens 1.1c-1.5c are made of the concrete which was used for the composite beam n1-c. the standard deviation and coefficient of variation of the results of this series is 2.43 mpa and 0.0503 respectively. other specimens 2.1c-2.4c are made of the concrete which was used to fill the beam n2-c. the standard deviation and coefficient of variation of the results of this series is 3.4 mpa and 0.0671 respectively. steel hsq beams were placed vertically and were gradually filled with concrete. the concrete was poured by 3-4 steps and compacted manually by using the steel bar. beam specimens are presented in fig. 1. the concrete specimens were casted at the same time. all the specimens were covered and left to cure under the laboratory conditions for 28 days. fig. 1. steel (left) and composite (right) beam specimens. nine cubic 100x100x100 specimens were tested under compression to find the compressive strength of the concrete which was used to fill the composite beams. six specimens (100x100x400) were tested under bending using one concentrated force applied at the centre. the bending resistance was later used to calculate the tensile strength of the concrete. four 100x100x300 specimens were also tested to find the elastic modulus of the concrete. toni technik 2020 press was used to test the concrete specimens. the arrangement of the beam bending experiment is presented in fig. 2 (left). the beam was placed on two supports: one hinge and one roller. the load was applied to the balance beam by the hydraulic press. the balance beam distributed the load on two cylinders with the base plates of 50 mm width. positions of supports and loads are presented in fig. 2 (right). fig. 2. experimental test setup (left) and load scheme (right). the 50 tons capacity hydraulic press grm-1 was used to test the beams. the load was applied to the beam by stages. preliminary analytical calculations were made before the start of the experiments to obtain the position of neutral axis and plastic bending resistance of each beam. at each stage the load was increased by approximately 10% of the calculated ultimate load during the period of 60-90 seconds. the displacements were measured by three deflection indicators (located at the supports and the middle of the beam) at each stage. finally, the deflection was calculated by eliminating the deformation of the supports. material properties cubic concrete specimens were tested under compression. the results are presented in the table 2. specimens 1.1c-1.5c are made of the concrete which was used for the composite beam n1-c. the standard deviation and coefficient of variation of the results of this series is 2.43 mpa and 0.0503 respectively. other specimens 2.1c-2.4c are made of the concrete which was used to fill the beam n2-c. the standard deviation and coefficient of variation of the results of this series is 3.4 mpa and 0.0671 respectively. steel hsq beams were placed vertically and were gradually filled with concrete. the concrete was poured by 3-4 steps and compacted manually by using the steel bar. beam specimens are presented in fig. 1. the concrete specimens were casted at the same time. all the specimens were covered and left to cure under the laboratory conditions for 28 days. fig. 1. steel (left) and composite (right) beam specimens. nine cubic 100x100x100 specimens were tested under compression to find the compressive strength of the concrete which was used to fill the composite beams. six specimens (100x100x400) were tested under bending using one concentrated force applied at the centre. the bending resistance was later used to calculate the tensile strength of the concrete. four 100x100x300 specimens were also tested to find the elastic modulus of the concrete. toni technik 2020 press was used to test the concrete specimens. the arrangement of the beam bending experiment is presented in fig. 2 (left). the beam was placed on two supports: one hinge and one roller. the load was applied to the balance beam by the hydraulic press. the balance beam distributed the load on two cylinders with the base plates of 50 mm width. positions of supports and loads are presented in fig. 2 (right). fig. 2. experimental test setup (left) and load scheme (right). the 50 tons capacity hydraulic press grm-1 was used to test the beams. the load was applied to the beam by stages. preliminary analytical calculations were made before the start of the experiments to obtain the position of neutral axis and plastic bending resistance of each beam. at each stage the load was increased by approximately 10% of the calculated ultimate load during the period of 60-90 seconds. the displacements were measured by three deflection indicators (located at the supports and the middle of the beam) at each stage. finally, the deflection was calculated by eliminating the deformation of the supports. material properties cubic concrete specimens were tested under compression. the results are presented in the table 2. specimens 1.1c-1.5c are made of the concrete which was used for the composite beam n1-c. the standard deviation and coefficient of variation of the results of this series is 2.43 mpa and 0.0503 respectively. other specimens 2.1c-2.4c are made of the concrete which was used to fill the beam n2-c. the standard deviation and coefficient of variation of the results of this series is 3.4 mpa and 0.0671 respectively. at the same time. all the specimens were covered and left to cure under the laboratory conditions for 28 days. nine cubic 100x100x100 specimens were tested under compression to find the compressive strength of the concrete which was used to fill the composite beams. six specimens (100x100x400) were tested under bending using one concentrated force applied at the centre. the bending resistance was later used to calculate the tensile strength of the concrete. four 100x100x300 specimens were also tested to find the elastic modulus of the concrete. toni technik 2020 press was used to test the concrete specimens. the arrangement of the beam bending experiment is presented in fig. 2 (left). the beam was placed on two supports: one hinge and one roller. the load was applied to the balance beam by the hydraulic press. the balance beam distributed the load on two cylinders with the base plates of 50 mm width. positions of supports and loads are presented in fig. 2 (right). the 50 tons capacity hydraulic press grm-1 was used to test the beams. the load was applied to the beam by stages. preliminary analytical calculations were made before the start of the experiments to obtain the position of neutral axis and plastic bending resistance of each beam. at each 91 journal of sustainable architecture and civil engineering 2018/1/22 stage the load was increased by approximately 10% of the calculated ultimate load during the period of 60-90 seconds. the displacements were measured by three deflection indicators (located at the supports and the middle of the beam) at each stage. finally, the deflection was calculated by eliminating the deformation of the supports. cubic concrete specimens were tested under compression. the results are presented in the table 2. specimens 1.1c-1.5c are made of the concrete which was used for the composite beam n1-c. the standard deviation and coefficient of variation of the results of this series is 2.43 mpa and 0.0503 respectively. other specimens 2.1c-2.4c are made of the concrete which was used to fill the beam n2-c. the standard deviation and coefficient of variation of the results of this series is 3.4 mpa and 0.0671 respectively. prism specimens were tested to find the modulus of elasticity of the concrete. the results are presented in the table 3. specimens 1.1e and 1.2e were made of the concrete which was used to fill the composite beam n1-c. the other two specimens were made of the concrete used for the beam n2-c. material properties table 2 dimensions and compressive strength of concrete cubes specimen mark b, mm h, mm f, kn fcub, mpa favg.cub, mpa fcm, mpa 1.1c 101.5 98.7 510.8 50.988 48.238 40.104 1.2c 100.6 99.5 498.6 49.812 1.3c 98.2 99.8 433.5 44.233 1.4c 98.6 101.2 466.9 46.791 1.5c 96.7 100.8 481.2 49.367 2.1c 100.5 100.5 525 51.979 50.643 41.638 2.2c 101.4 101.9 470.1 45.497 2.3c 100.9 100.7 500 49.210 2.4c 101.1 100.3 566.7 55.886 table 3 dimensions and modulus of elasticity of concrete prisms only two specimens were casted for each of the series. for the statistical analysis the possible scatter of the results could be evaluated by using the coefficient of variation of similar specimens tested in the research carried out by kelpša (2017). coefficient of variation of the results of the modulus of elasticity was 0.0229 in the research of kelpša (2017). as a consequence, the standard deviation for the specimens 1.1e and 1.2e is 713.7 mpa and 716.3 mpa for the specimens 2.1e and 2.2e. according to those values, it can be stated that the results are reasonable. when the reliability is 0.95, the maximum standard deviation is 887.3 mpa for the specimens 1.1e and 1.2e and 890.5 mpa for the specimens 2.1e and 2.2e which is only 2.85 % of the maximum error. prism specimens were tested to find the bending resistance of the concrete. obtained results were used to calculate the tensile strength of concrete. the results are presented in table 4. specimen mark b, mm h, mm e, gpa eavg, gpa 1.1e 100.6 99.3 31.216 31.167 1.2e 101.5 100.4 31.117 2.1e 102.1 100.6 31.246 31.281 2.2e 101.7 99.5 31.315 specimen mark b, mm h, mm f, kn fctm,fl, mpa fct, mpa fctm, mpa 1.1t 99.1 99.5 10.85 5.640 3.759 3.7671.2t 98.6 101.9 11.35 5.654 3.774 1.3t 100.7 100.1 11.18 5.651 3.767 2.1t 99.8 102.2 12.51 6.121 4.086 3.8532.2t 99.2 100.8 11.15 5.642 3.763 2.3t 98.8 101.1 11.01 5.560 3.710 table 4 dimensions, bending resistance and tensile strength of concrete prisms journal of sustainable architecture and civil engineering 2018/1/22 92 three specimens were casted for each of the two series. the reliability of the results of the tensile strength was evaluated in the same way as the results of the modulus of elasticity. the coefficient of variation of the results of the tensile strength was 0.099 in the research of kelpša (2017). in this case, the maximum error is 17 % which is reasonable for the results of the tensile strength. steel had a grade of s355j2+n, but it was not tested during the experimental programme. the assumed stress-strain curve is presented in fig. 5. fig. 3 load-displacement curves of experimental beams load-displacement curves of the beams are presented in fig. 3. the loading of the steel beams (n1-s and n2-s) was stopped soon after the first plastic deformations occurred. it was due to the fact that the webs of the steel beams started to buckle locally in the places where the load was applied. when the buckling occurred, the resistance of the beams started to decrease. the deflection at the moment when the experiment was stopped was 8-9 mm. the early local buckling occurred partly due to discontinuous welding between webs and flanges of the beam which caused stress concentrations. the composite beams (n1-c and n2-c) reached plastic bending resistance and their load-displacement curves were almost horizontal when the experiment was stopped (fig. 3). there was experimental results experimental results load-displacement curves of the beams are presented in fig. 3. the loading of the steel beams (n1-s and n2-s) was stopped soon after the first plastic deformations occurred. it was due to the fact that the webs of the steel beams started to buckle locally in the places where the load was applied. when the buckling occurred, the resistance of the beams started to decrease. the deflection at the moment when the experiment was stopped was 8-9 mm. the early local buckling occurred partly due to discontinuous welding between webs and flanges of the beam which caused stress concentrations. the composite beams (n1-c and n2-c) reached plastic bending resistance and their loaddisplacement curves were almost horizontal when the experiment was stopped (fig. 3). there was no sudden collapse and no local buckling was observed in this case. the bending of the composite beams was stopped when the displacement was increasing without increasing the load. fig. 3. load-displacement curves of experimental beams. it was noticed that the composite beams possessed a 52-74 % higher bending resistance than the steel beams. furthermore, the first plastic deformations in the composite beams occurred when the 35-50 % higher load was applied. beams filled with concrete also had an increased resistance to local buckling. as a consequence, it can be stated that filling the hsq beam with concrete had a positive effect on the flexural behaviour. although more materials were used, the concrete is relatively cheap compared to steel. furthermore, filling the beam with concrete should also increase the fire resistance of the construction. however, to prove and evaluate this increase of fire resistance, further research is required. finite element modelling of experimental beams finite element analysis (fea) software abaqus was used during this research. four numerical finite element models (fem) were created to analyse the load-deflection behaviour of the experimental beams. material properties and constitutive models non-linear stress-strain material model of confined concrete suggested by han (2001) was used in this research. the model assumes that the concrete confined by the steel profile reaches a higher compressive strength than fcm. it also suggests that after reaching the compressive strength the concrete becomes more plastic and its resistance decreases slower than the resistance of the regular concrete. the main parameter in this model is confinement factor ζ which depends on the crosssectional area of concrete and steel, yield strength of steel and compressive strength of concrete: 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 b en di ng m om en t, kn m deflection, mm n1-c n2-c n1-s n2-s no sudden collapse and no local buckling was observed in this case. the bending of the composite beams was stopped when the displacement was increasing without increasing the load. it was noticed that the composite beams possessed a 52-74 % higher bending resistance than the steel beams. furthermore, the first plastic deformations in the composite beams occurred when the 35-50 % higher load was applied. beams filled with concrete also had an increased resistance to local buckling. as a consequence, it can be stated that filling the hsq beam with concrete had a positive effect on the flexural behaviour. although more materials were used, the concrete is relatively cheap compared to steel. furthermore, filling the beam with concrete should also increase the fire resistance of the construction. however, to prove and evaluate this increase of fire resistance, further research is required. finite element modelling of experimental beams finite element analysis (fea) software abaqus was used during this research. four numerical finite element models (fem) were created to analyse the load-deflection behaviour of the experimental beams. material properties and constitutive models non-linear stress-strain material model of confined concrete suggested by han (2001) was used in this research. the model assumes that the concrete confined by the steel profile reaches a higher compressive strength than fcm. it also suggests that after reaching the compressive strength the concrete becomes more plastic and its resistance decreases slower than the resistance of the regular concrete. the main parameter in this model is confinement factor ζ which depends on the cross-sectional area of concrete and steel, yield strength of steel and compressive strength of concrete: 93 journal of sustainable architecture and civil engineering 2018/1/22 æ s sy c ck a f a f ⋅ = ⋅ (1) where: – cross-sectional area of steel profile; – cross-sectional area of concrete; – yield strength of steel; – compressive strength of concrete which is calculated as 67% of the compressive strength of cubic blocks. the behaviour of concrete was described by the stress and non-linear strain dependence in the “concrete damaged plasticity model” in abaqus. this model is a continuum, plasticity-based, damage model for concrete. it assumes that the main two failure mechanisms are tensile cracking and compressive crushing of the concrete material. it was assumed that the concrete has a poisson’s ratio of 0.2. the stress-strain dependence of the tested concrete is presented in fig. 4. elastic modulus of the steel was assumed to be 210.6 gpa and poisson’s ratio – 0.3. plastic properties were described as the true stress-plastic strain dependence. the model of steel fig. 4 stress-strain dependence of confined concrete fig. 5 stress-strain dependence of steel ζ s sy c ck a f a f    (1) where: as – cross-sectional area of steel profile; ac – cross-sectional area of concrete; fsy – yield strength of steel; fck – compressive strength of concrete which is calculated as 67% of the compressive strength of cubic blocks. the behaviour of concrete was described by the stress and non-linear strain dependence in the “concrete damaged plasticity model” in abaqus. this model is a continuum, plasticity-based, damage model for concrete. it assumes that the main two failure mechanisms are tensile cracking and compressive crushing of the concrete material. it was assumed that the concrete has a poisson’s ratio of 0.2. the stress-strain dependence of the tested concrete is presented in fig. 4. fig. 4. stress-strain dependence of confined concrete. elastic modulus of the steel was assumed to be 210.6 gpa and poisson’s ratio – 0.3. plastic properties were described as the true stress-plastic strain dependence. the model of steel proposed by han (2001) was used in this research. the steel grade was known to be s355, but the exact yield and ultimate strength was not tested during this research. however, different authors have found that the yield strength of steel (grade s355) is usually higher than 400 mpa. outinen, j. and mäkeläinen, p. (1995) have reported that their tested s355 class steel had a yield strength of 406.1 mpa, ultimate stress of 526.9 mpa and elasticity modulus of 210.6 gpa. the same values have also been used in the finite element analysis of this research. it was chosen to use those values in order to fit the experimental and fea results better. the stress-strain dependence used for the analysis of the beams in abaqus is presented in fig. 5. fig. 5. stress-strain dependence of steel. elements, mesh, contact and boundary conditions 0 5 10 15 20 25 30 35 40 45 50 0 0,002 0,004 0,006 0,008 0,01 0,012 0,014 0,016 st re ss , m pa strain concrete n1-c concrete n2-c 0 100 200 300 400 500 600 0 0,025 0,05 0,075 0,1 0,125 0,15 0,175 0,2 0,225 0,25 st re ss , m pa strain ζ s sy c ck a f a f    (1) where: as – cross-sectional area of steel profile; ac – cross-sectional area of concrete; fsy – yield strength of steel; fck – compressive strength of concrete which is calculated as 67% of the compressive strength of cubic blocks. the behaviour of concrete was described by the stress and non-linear strain dependence in the “concrete damaged plasticity model” in abaqus. this model is a continuum, plasticity-based, damage model for concrete. it assumes that the main two failure mechanisms are tensile cracking and compressive crushing of the concrete material. it was assumed that the concrete has a poisson’s ratio of 0.2. the stress-strain dependence of the tested concrete is presented in fig. 4. fig. 4. stress-strain dependence of confined concrete. elastic modulus of the steel was assumed to be 210.6 gpa and poisson’s ratio – 0.3. plastic properties were described as the true stress-plastic strain dependence. the model of steel proposed by han (2001) was used in this research. the steel grade was known to be s355, but the exact yield and ultimate strength was not tested during this research. however, different authors have found that the yield strength of steel (grade s355) is usually higher than 400 mpa. outinen, j. and mäkeläinen, p. (1995) have reported that their tested s355 class steel had a yield strength of 406.1 mpa, ultimate stress of 526.9 mpa and elasticity modulus of 210.6 gpa. the same values have also been used in the finite element analysis of this research. it was chosen to use those values in order to fit the experimental and fea results better. the stress-strain dependence used for the analysis of the beams in abaqus is presented in fig. 5. fig. 5. stress-strain dependence of steel. elements, mesh, contact and boundary conditions 0 5 10 15 20 25 30 35 40 45 50 0 0,002 0,004 0,006 0,008 0,01 0,012 0,014 0,016 st re ss , m pa strain concrete n1-c concrete n2-c 0 100 200 300 400 500 600 0 0,025 0,05 0,075 0,1 0,125 0,15 0,175 0,2 0,225 0,25 st re ss , m pa strain proposed by han (2001) was used in this research. the steel grade was known to be s355, but the exact yield and ultimate strength was not tested during this research. however, different authors have found that the yield strength of steel (grade s355) is usually higher than 400 mpa. outinen, j. and mäkeläinen, p. (1995) have reported that their tested s355 class steel had a yield strength of 406.1 mpa, ultimate stress of 526.9 mpa and elasticity modulus of 210.6 gpa. the same values have also been used in the finite element analysis of this research. it was chosen to use those values in order to fit the experimental and fea results better. the stress-strain dependence used for the analysis of the beams in abaqus is presented in fig. 5. elements, mesh, contact and boundary conditions c3dr 8-node linear bricks with reduced integration have been used as the elements for steel and concrete. the finite element problem includes local buckling and it was found that the results depend on the size of mesh. by trying different mesh size, it was found that the fem results were closest to experimental when 12 mm elements were used. the bigger size of mesh led to a stiffer load-deflection behaviour and the smaller size of mesh made the beam more susceptible to local buckling. composite and steel beam models consisted of approximately 5000-6000 and 80009000 elements respectively. composite beams had less elements because only the quarter of each composite beam was modelled to minimize the time needed for the fem calculation. the steel beams have been connected to the bottom plates using “tie-constraint” command. botjournal of sustainable architecture and civil engineering 2018/1/22 94 tom plates have been supported using one hinged and one roller support. contact between the steel profile and loading plates was described as a frictional behaviour with the coefficient of 0.74 as stated by grigoriev, i. et al. (1997). fig. 6 positions of plates and contact properties c3dr 8-node linear bricks with reduced integration have been used as the elements for steel and concrete. the finite element problem includes local buckling and it was found that the results depend on the size of mesh. by trying different mesh size, it was found that the fem results were closest to experimental when 12 mm elements were used. the bigger size of mesh led to a stiffer load-deflection behaviour and the smaller size of mesh made the beam more susceptible to local buckling. composite and steel beam models consisted of approximately 5000-6000 and 8000-9000 elements respectively. composite beams had less elements because only the quarter of each composite beam was modelled to minimize the time needed for the fem calculation. the steel beams have been connected to the bottom plates using “tie-constraint” command. bottom plates have been supported using one hinged and one roller support. contact between the steel profile and loading plates was described as a frictional behaviour with the coefficient of 0.74 as stated by grigoriev, i. et al. (1997). a quarter of the model was created for both of the composite beams. constraints in the directions of two axes were added to simulate the symmetry planes. contact between the steel profile and concrete was described as a frictional behaviour with the coefficient of 0.65 as stated by rabbat, b. g. and russell, h. g. (1985). positions of plates and their contact properties are presented in fig. 6. fig. 6. positions of plates and contact properties. the principal scheme was presented in fig. 2. in abaqus, the line supports were added to the bottom surfaces of the support plates. left and right support plate was supported with a hinged and roller support respectively. line load was applied to the loading plates on top of the beams. it was described as a gradually increasing load until the midpoint of the beam reached a prescribed deflection. comparison of fem and experimental results the fea has been carried out. load-deflection curves were obtained. the comparison between the experimental and fea results of the beams n1-s and n1-c is presented in fig. 7. it is noticeable that the fem models managed to capture the load-deflection behaviour accurately. the bending moment of the beam n1-s in fem analysis was found to be higher by 5.5 % than the experimental moment at the maximum experimental deflection (9 mm). however, experimental beam n1-c exhibited a stiffer load-deflection behaviour than the fem model shows. the experimental bending moment was higher by 4 % than the fem bending moment when the plastic bending resistance was reached (horizontal part of the curves n1-c and fem: n1c). fig. 7. comparison of experimental and fea load-deflection behaviour of beams n1-s and n1-c. the comparison between the experimental and fea results of the beams n2-s and n2-c is presented in fig. 8. the load-deflection behaviour exhibits similar tendencies as the beams discussed before. the bending moment of the beam n2-s in fem model was found to be higher by 1 % than experimental moment at the maximum experimental deflection (8.6 mm). beam n2-c analysed by fem has reached the same deflection when the bending moment was higher by up to 1.5 % in the plastic region of the load-deflection curve. fig. 8. comparison of experimental and fea load-deflection behaviour of beams n2-s and n2-c. the difference of the bending moments at the same deflection was up to 5.5 % considering all of the beams. this leads to the conclusion that the material models were chosen appropriately. the most likely source of inaccuracy is the fact that the steel tension tests have not been carried out. the yield strength of the steel was assumed to be 406.1 mpa and ultimate stress – 526.9 mpa. it could have been marginally different for individual beams and for elements having a different thickness. furthermore, the welds between plate elements of beams were discontinuous. this led to the decreased bending capacity of the beams. 0 5 10 15 20 25 30 35 40 45 50 55 60 65 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 b en di ng m om en t, kn m deflection, mm n1-s fem: n1-s n1-c fem: n1-c 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 b en di ng m om en t, kn m deflection, mm n2-s fem: n2-s n2-c fem: n2-c fig. 7 comparison of experimental and fea load-deflection behaviour of beams n1-s and n1-c a quarter of the model was created for both of the composite beams. constraints in the directions of two axes were added to simulate the symmetry planes. contact between the steel profile and concrete was described as a frictional behaviour with the coefficient of 0.65 as stated by rabbat, b. g. and russell, h. g. (1985). positions of plates and their contact properties are presented in fig. 6. the principal scheme was presented in fig. 2. in abaqus, the line supports were added to the bottom surfaces of the support plates. left and right support plate was supported with a hinged and roller support respectively. line load was applied to the loading plates on top of the beams. it was described as a gradually increasing load until the midpoint of the beam reached a prescribed deflection. comparison of fem and experimental results the fea has been carried out. load-deflection curves were obtained. the comparison between the experimental and fea results of the beams n1-s and n1-c is presented in fig. 7. it is noticeable that the fem models managed to capture the load-deflection behaviour accurately. the bending moment of the beam n1-s in fem analysis was found to be higher by 5.5 % than the experimental moment at the maximum experimental deflection (9 mm). however, experimental beam n1-c exhibited a stiffer load-deflection behaviour than the fem model shows. the experimental bending moment was higher by 4 % than the fem bending moment when the plastic bending resistance was reached (horizontal part of the curves n1-c and fem: n1-c). the comparison between the experimental and fea results of the beams n2-s and n2-c is presented in fig. 8. the load-deflection behaviour exhibits similar tendencies as the beams discussed 95 journal of sustainable architecture and civil engineering 2018/1/22 before. the bending moment of the beam n2-s in fem model was found to be higher by 1 % than experimental moment at the maximum experimental deflection (8.6 mm). beam n2-c analysed by fem has reached the same deflection when the bending moment was higher by up to 1.5 % in the plastic region of the load-deflection curve. the difference of the bending moments at the same deflection was up to 5.5 % considering all of the beams. this leads to the conclusion that the material models were chosen appropriately. the most likely source of inaccuracy is the fact that the steel tension tests have not been carried out. the yield strength of the steel was assumed to be 406.1 mpa and ultimate stress – 526.9 mpa. it could have been marginally different for individual beams and for elements having a different thickness. furthermore, the welds between plate elements of beams were discontinuous. this led to the decreased bending capacity of the beams. verification of the finite element model in order to evaluate the validity of the chosen finite element modelling techniques in this paper three more beams have been analysed by fem. the experimental tests for those beams have been carried out by han (2004). the yield strength of the steel was tested by the author. han (2004) has found that the steel of the beams rb1-1, rb3-1 and rb3-2 had a yield strength of 330.1 mpa, 321.1 and 321.1 mpa respectively. the author has also made a prediction of the load-deflection behaviour using a theoretical method. the experimental and theoretical load-deflection curves of the beams rb1-1, rb3-1 and rb3-2 are presented in fig. 9. the load-deflection curves obtained during this research using fem are presented in the same charts. it is noticeable that han’s (2004) theoretical predictions were close to his experimental results. all of the beams have shown a similar trend. first plastic deformations during han’s (2004) experiments occurred earlier than those in the theoretical han’s (2004) predictions. furthermore, it can be seen that when considerable plastic deformations occur and the deflection is more than 16 mm a higher load is needed to reach the same deflection in the experimental situation. the experimental load is higher by up to 8 % than han’s theoretical prediction when the deflection is 24 mm. fig. 7. comparison of experimental and fea load-deflection behaviour of beams n1-s and n1-c. the comparison between the experimental and fea results of the beams n2-s and n2-c is presented in fig. 8. the load-deflection behaviour exhibits similar tendencies as the beams discussed before. the bending moment of the beam n2-s in fem model was found to be higher by 1 % than experimental moment at the maximum experimental deflection (8.6 mm). beam n2-c analysed by fem has reached the same deflection when the bending moment was higher by up to 1.5 % in the plastic region of the load-deflection curve. fig. 8. comparison of experimental and fea load-deflection behaviour of beams n2-s and n2-c. the difference of the bending moments at the same deflection was up to 5.5 % considering all of the beams. this leads to the conclusion that the material models were chosen appropriately. the most likely source of inaccuracy is the fact that the steel tension tests have not been carried out. the yield strength of the steel was assumed to be 406.1 mpa and ultimate stress – 526.9 mpa. it could have been marginally different for individual beams and for elements having a different thickness. furthermore, the welds between plate elements of beams were discontinuous. this led to the decreased bending capacity of the beams. 0 5 10 15 20 25 30 35 40 45 50 55 60 65 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 b en di ng m om en t, kn m deflection, mm n1-s fem: n1-s n1-c fem: n1-c 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 b en di ng m om en t, kn m deflection, mm n2-s fem: n2-s n2-c fem: n2-c fig. 8 comparison of experimental and fea load-deflection behaviour of beams n2-s and n2-c journal of sustainable architecture and civil engineering 2018/1/22 96 the difference is smaller when the deflection is lower. however, it shows a trend of an increasing difference when the deflection is increasing. han‘s (2004) theoretical prediction has shown very similar results to the fea prediction made during this research. it was noticed that the fea prediction is more accurate in the load-deflection curve region where the first plastic deformations occur. for example, when the deflection is equal to 4 mm, han‘s (2004) theoretical load prediction is up to 16 % higher than the load during the experiment. load obtained by fem during this research is up to 9 % higher than han‘s (2004) experimental load, when the deflection is 4 mm. fig. 9 han’s (2004) experimental, han’s (2004) theoretical and fem load-deflection curves of beam rb1-1 (left) and beams rb3-1, rb3-2 (right) verification of the finite element model in order to evaluate the validity of the chosen finite element modelling techniques in this paper three more beams have been analysed by fem. the experimental tests for those beams have been carried out by han (2004). the yield strength of the steel was tested by the author. han (2004) has found that the steel of the beams rb1-1, rb3-1 and rb3-2 had a yield strength of 330.1 mpa, 321.1 and 321.1 mpa respectively. the author has also made a prediction of the load-deflection behaviour using a theoretical method. the experimental and theoretical load-deflection curves of the beams rb1-1, rb3-1 and rb32 are presented in fig. 9. the load-deflection curves obtained during this research using fem are presented in the same charts. fig. 9. han’s (2004) experimental, han’s (2004) theoretical and fem load-deflection curves of beam rb1-1 (left) and beams rb3-1, rb3-2 (right). it is noticeable that han’s (2004) theoretical predictions were close to his experimental results. all of the beams have shown a similar trend. first plastic deformations during han’s (2004) experiments occurred earlier than those in the theoretical han’s (2004) predictions. furthermore, it can be seen that when considerable plastic deformations occur and the deflection is more than 16 mm a higher load is needed to reach the same deflection in the experimental situation. the experimental load is higher by up to 8 % than han’s theoretical prediction when the deflection is 24 mm. the difference is smaller when the deflection is lower. however, it shows a trend of an increasing difference when the deflection is increasing. han‘s (2004) theoretical prediction has shown very similar results to the fea prediction made during this research. it was noticed that the fea prediction is more accurate in the load-deflection curve region where the first plastic deformations occur. for example, when the deflection is equal to 4 mm, han‘s (2004) theoretical load prediction is up to 16 % higher than the load during the experiment. load obtained by fem during this research is up to 9 % higher than han‘s (2004) experimental load, when the deflection is 4 mm. 0 5 10 15 20 25 30 35 0 2 4 6 8 10 12 14 16 18 20 22 24 b en di ng m om en t, kn m deflection, mm fem: rb1-1 han's prediction: rb1-1 han's experiment: rb1-1 0 5 10 15 20 25 30 35 40 45 0 2 4 6 8 10 12 14 16 18 20 22 24 b en di ng m om en t, kn m deflection, mm fem: rb-3 han's prediction: rb-3 han's experiment: rb3-1 han's experiment: rb3-2 verification of the finite element model in order to evaluate the validity of the chosen finite element modelling techniques in this paper three more beams have been analysed by fem. the experimental tests for those beams have been carried out by han (2004). the yield strength of the steel was tested by the author. han (2004) has found that the steel of the beams rb1-1, rb3-1 and rb3-2 had a yield strength of 330.1 mpa, 321.1 and 321.1 mpa respectively. the author has also made a prediction of the load-deflection behaviour using a theoretical method. the experimental and theoretical load-deflection curves of the beams rb1-1, rb3-1 and rb32 are presented in fig. 9. the load-deflection curves obtained during this research using fem are presented in the same charts. fig. 9. han’s (2004) experimental, han’s (2004) theoretical and fem load-deflection curves of beam rb1-1 (left) and beams rb3-1, rb3-2 (right). it is noticeable that han’s (2004) theoretical predictions were close to his experimental results. all of the beams have shown a similar trend. first plastic deformations during han’s (2004) experiments occurred earlier than those in the theoretical han’s (2004) predictions. furthermore, it can be seen that when considerable plastic deformations occur and the deflection is more than 16 mm a higher load is needed to reach the same deflection in the experimental situation. the experimental load is higher by up to 8 % than han’s theoretical prediction when the deflection is 24 mm. the difference is smaller when the deflection is lower. however, it shows a trend of an increasing difference when the deflection is increasing. han‘s (2004) theoretical prediction has shown very similar results to the fea prediction made during this research. it was noticed that the fea prediction is more accurate in the load-deflection curve region where the first plastic deformations occur. for example, when the deflection is equal to 4 mm, han‘s (2004) theoretical load prediction is up to 16 % higher than the load during the experiment. load obtained by fem during this research is up to 9 % higher than han‘s (2004) experimental load, when the deflection is 4 mm. 0 5 10 15 20 25 30 35 0 2 4 6 8 10 12 14 16 18 20 22 24 b en di ng m om en t, kn m deflection, mm fem: rb1-1 han's prediction: rb1-1 han's experiment: rb1-1 0 5 10 15 20 25 30 35 40 45 0 2 4 6 8 10 12 14 16 18 20 22 24 b en di ng m om en t, kn m deflection, mm fem: rb-3 han's prediction: rb-3 han's experiment: rb3-1 han's experiment: rb3-2 1 experimental tests have shown that the composite beams possessed a 52-74 % higher bending resistance than the steel beams. the first plastic deformations in the composite beams occurred when the 35-50 % higher load was applied. 2 during the finite element analysis of the tested hsq beams it has been found that the fem load at the same deflection for the steel beams was up to 5.5 % higher than the experimental load. the difference of the load for the composite beams was up to 4 %. as expected, the experimental beams have exhibited a softer load-deflection behaviour than the fem models, because the experimental beams consisted of separate steel plates welded with discontinuous welds which caused local stress concentrations while fem beams were modelled as a single profile without welds. 3 fea carried out in this research has shown similar but more exact results than han’s theo-retical prediction compared to han’s experimental load-deflection curves of the composite beams. han’s theoretically predicted load was up to 16 % higher than the experimental load when the first plastic deformations occurred and the deflection was 4 mm. the difference between fem load and experimental load was only 9 %. when the deflection was 24 mm, experimental load was up to 8 % higher than both han’s theoretically predicted load and fem predicted load in this research. although han’s theoretical beam calculation method is easier to use than fem, the usage of it is restricted to rectangular composite profiles only, while fem is a universal method which also yields more exact results. conclusions 97 journal of sustainable architecture and civil engineering 2018/1/22 4 han‘s stress-strain models of steel and confined concrete proved to be suitable to obtain the relatively accurate fem prediction of the load-deflection behaviour of steel and composite beams. to increase the precision of fem results further, it is suggested to evaluate the initial geometrical imperfections and residual stresses of welded steel plates. 5 it is necessary to carry out a mesh sensitivity analysis when analysing steel and composite beams using fem. it was noticed that the most accurate results for most of the models were obtained when using 12 mm mesh size. increasing the mesh size of the composite beam to 15 mm led to a stiffer load-deflection behaviour and up to 4 % higher plastic bending resistance while beams with a mesh size of 10 mm had a 3 % lower plastic bending resistance. the mesh size of the steel beam had a higher impact on the results. up to 6 % higher and up to 5% lower plastic bending resistances were observed when using 15 mm and 10 mm mesh respectively compared to the results obtained when using 12 mm mesh size. decreasing the mesh size further, in most cases has shown an increased tendency to the local buckling of the steel profile at the load application and support zones. 6 filling the steel hsq beam with concrete increased the stiffness and bending resistance of it significantly. in order to develop the concept of a composite hsq beam, it is suggested to carry out a further research on the steel bar reinforced composite hsq beams and evaluate the fire resistance of it. bzdawka, k. optimization of office building frame with semi-rigid joints in normal and fire conditions. tampere: tampere university of technology; 2012. isbn 978-952-15-2808-8. en 1992-1-1:2004. eurocode 2: design of concrete structures – part 1-1: general rules and rules for buildings. en 1993-1-1:2005. eurocode 3: design of steel structures – part 1-1: general rules and rules for buildings. grigoriev, i., meilikhov, e. and radzig, a. crc handbook of physical quantities. boca raton: crc press; 1997. isbn 9780849328619. han, l. flexural behaviour of concrete-filled steel tubes. journal of constructional steel research, 2004, 60.2: 313-337. https://doi.org/10.1016/j. jcsr.2003.08.009. han, l., zhao, x. and tao, z. tests and mechanics model for concrete-filled shs stub columns, columns and beam-columns. steel and composite structures, 2001, 1(1): 51-74. https://doi. org/10.1296/scs2001.01.01.04 hassanein, m.f., kharoob, o.f. and taman, m.h. experimental investigation of cementitious material-filled square thin-walled steel beams. thin walled structures, 2017, 114: 134-143. https://doi. org/10.1016/j.tws.2017.01.031 huang, c., yeh, y., liu, g. and hu, h. axial load behavior of stiffened concrete-filled steel columns. journal of structural engineering, 2002, 128(9): 1222-1230. https://doi.org/10.1061/(asce)07339445(2002)128:9(1222) kelpša, š. plieno plaušo įtaka lenkiamų gelžbetoninių elementų pleišėjimui ir standumui: doctoral dissertation : technological sciences, civil engineering (02t). kaunas: 2017. isbn 9786090212981. lu, f.w., li, s.p., li, d.w. and sun, g. flexural behavior of concrete filled non-uni-thickness walled rectangular steel tube. journal of constructional steel research, 2007, 63(8): 1051-1057. https://doi. org/10.1016/j.jcsr.2006.09.006 outinen, j. and mäkeläinen, p. transient state tensile test results of structural steel s355 (raex 37-52) at elevated temperatures. rakenteiden mekaniikka, 1995, 28(1): 3-18. isbn 0783-6104. pajari, m. prestressed hollow core slabs supported on beams. finnish shear tests on floors in 1990– 2006. tampere: vtt technical research centre of finland; 2010. isbn 978-951-38-7495-7. rabbat, b. g. and russell, h. g. friction coefficient of steel on concrete or grout. journal of structural engineering, 1985, 111(3): 505-515. https://doi. org/10.1061/(asce)0733-9445(1985)111:3(505) schneider, s. p. axially loaded concrete-filled steel tubes. journal of structural engineering, 1998, 124(10): 1125-1138. https://doi.org/10.1061/ (asce)0733-9445(1998)124:10(1125) soundararajan, a. and shanmugasundaram, k. flexural behaviour of concrete-filled steel hollow sections beams. journal of civil engineering and references journal of sustainable architecture and civil engineering 2018/1/22 98 management, 2008, 14(2): 107-114. https://doi. org/10.3846/1392-3730.2008.14.5 tomii, m., sakino, k. elasto-plastic behavior of concrete filled square steel tubular beam-columns. transactions of the architectural institute of japan, 1979, 280: 111-122. https://doi.org/10.3130/aijsaxx.280.0_111 zhan, y., zhao, r., john ma, z., xu, t. and song, r. behavior of prestressed concrete-filled steel tube (cfst) beam. engineering structures, 2016, vol. 122: 144-155. https://doi.org/10.1016/j.engstruct.2016.04.050 deividas martinavičius phd student kaunas university of technology, faculty of civil engineering and architecture main research area strength and stability of steel and concrete composite structures address studentu st. 48, lt-51367, kaunas, lithuania tel. +370 616 87407 e-mail: deividas. martinavicius@ktu.edu mindaugas augonis assoc. professor kaunas university of technology, faculty of civil engineering and architecture main research area durability of engineering structures, strength and stability or reinforced concrete structures address studentu st. 48, lt-51367, kaunas, lithuania tel. +370 616 24115 e-mail: mindaugas. augonis@ktu.lt nerijus adamukaitis dr. lecturer kaunas university of technology, faculty of civil engineering and architecture main research area durability of engineering structures, strength and stability or steel structures address studentu st. 48, lt-51367, kaunas, lithuania tel. +370 627 59789 e-mail: nerijus. adamukaitis@ktu.lt tadas zingaila phd student kaunas university of technology, faculty of civil engineering and architecture main research area strength, stability and serviceability of reinforced concrete and uhpfrc structures address studentu st. 48, lt-51367, kaunas, lithuania tel. +370 615 41075 e-mail: tadas.zingaila@ ktu.edu about the authors journal of sustainable architecture and civil engineering 2015/4/13 28 journal of sustainable architecture and civil engineering vol. 4 / no. 13 / 2015 pp. 28-38 doi 10.5755/j01.sace.13.4.12862 © kaunas university of technology received 2015/08/10 accepted after revision 2015/11/04 integration of building information modelling (bim) and life cycle assessment (lca) for sustainable constructions jsace 4/13 integration of building information modelling (bim) and life cycle assessment (lca) for sustainable constructions corresponding author: res.ka@frederick.ac.cy http://dx.doi.org/10.5755/j01.sace.13.4.12862 angeliki kylili, paris a. fokaides frederick university, cyprus, school of engineering and applied sciences 7, frederickou str., 1036, nicosia, cyprus juozas vaiciunas, lina seduikyte kaunas university of technology, faculty of civil engineering and architecture studentu g. 48, kaunas, lithuania the construction industry and the scientific community continue to seek for innovative approaches that can estimate the level of sustainability to be achieved at the end of the project from the early design stages. one of the tools developed for this purpose is building information modelling (bim), which represents the stateoftheart tool for bringing together different expertise and achieving optimal designs at an early design stage for the maximization of their impact. the key objective of this work is to expand the level of the prospect of this tool, which is believed not to have been fully exploited. within this context, this paper integrates bim with an established methodology for assessing a product’s or a system’s environmental performance – life cycle assessment (lca) − in an attempt to maximize the benefits from this synergy and achieve the most sustainable constructions. the impact from the integration of these two valuable tools is presented for a water supply system using case studies for a range of different materials. comparison of a modern vernetztes polyethylen (vpe) water supply system against two systems made from traditional materials (steel and copper) was made. the results of this study show that a vpe water supply system performs at least 75% better than the steel system, and at least 88% better than a copper water supply system across all lca impact categories, while the carbon dioxide emissions released during the production of a vpe system are almost the one tenth of traditional materials water supply systems. keywords: building information modelling (bim), life cycle assessment (lca), material, sustainability, water supply system, facility, building. 29 journal of sustainable architecture and civil engineering 2015/4/13 introduction the building sector constitutes the largest energy consumer in europe, establishing the construction industry as one of the most significant contributors to the burdening of the natural environment. accordingly, during the past decade the industry has taken huge steps towards the greening of the buildings sector, and constantly searches for novel and effective approaches to achieve the most sustainable constructions, as specified by the european union directive on the energy performance of buildings (directive 2010/31/ec). building information modeling (bim) is defined as a digital representation of the physical and functional characteristics of a facility. a bim is a shared knowledge resource for information about a facility forming a reliable basis for decisions during its life-cycle; defined as existing from earliest conception to demolition (national institute of building sciences, 2014). the employment of such information systems has penetrated the construction industry, due to their ability in enhancing the effectiveness of construction projects not only throughout their life cycle, but also across different construction business functions (jung and joo, 2011). accordingly, a range of stakeholders involved in a construction project can retrieve and generate information from the same model, thus allowing them to work cohesively (ding et al., 2014). nonetheless, the potential of bim is envisioned to grow larger if further exploited through its integration with another life cycle approach. bim has been reported to support various tasks within the construction industry, among of which building energy performance analysis studies. bim provides a platform based on which building energy saving design can be structured (yuan and yuan, 2011). shoubi et al. (2015) utilized bim for the assessment of various combinations of materials for the reduction of the operational energy use of the building. ladenhauf et al. (2014) presented an algorithm for the preparation of input data for energy analysis based on building information models. similarly, ham and golparvar-fard (2015) presented a system, together with new methods for automated association and updating of actual thermal property measurements with bim elements in green building extensible markup language (gbxml) schema for improving the reliability of building energy modelling. lca is a standardized methodology for the systematic analysis of the environmental performance of processes or products throughout their whole lifecycle (en iso 14040: 2006). lca has been employed in the building sector since the 90s, and currently represents an established objective method for evaluating the environmental impact of construction practices (cabeza et al., 2014a). rønning and brekke (2014) have confirmed the effectiveness of the methodology in informing decision makers on the environmental performance of buildings. in fact, it has been reported that lca has been used to assess the environmental performance of a range of different building materials including concrete and mortar (marinković, 2013; brás and gomes, 2015), building thermal insulation materials (dylewski and adamczyk, 2014; pargana et al., 2014), wood constructions (guardiglia et al., 2011; sathre and gonzález-garcía, 2014), phase changing materials (pcm) (cabeza et al., 2014b), and windows (salazar, 2014). however, only a limited number of studies have integrated bim with the lca methodology to either investigate the environmental performance of a building element or of a whole building at an early design stage. on the one hand, bim supports integrated design and improves information management and cooperation between the different stakeholders, and on the other hand, lca is a suitable method for assessing environmental performance (anton and diaz, 2014). in fact, kulahcioglu et al. (2012) presented a prototype software, which allows the interactive analysis of a 3d building model with its environmental impacts. in the case of wang et al. (2011), bim was employed to conduct whole building lca based on a 50year lifetime. the results of their study indicated that the most effective design in terms of energy savings was replacing the curtain walls with brick walls for the top three floors. ajayi et al. (2015) also carried out a bim-enhanced lca journal of sustainable architecture and civil engineering 2015/4/13 30 for a whole twofloor building. in this case, a 30year lifecycle period was assumed for the conductance of a variability analysis on the design and materials. regarding the design analysis, the work were revealed that timber house are the most environmental ones. these results come in agreement with the findings of iddon et al. (2013), where the timber framed design of a typical detached house had the lowest total co2 equiv. emissions (213t co2) over the 60 year lifespan among the other investigated designs. also, the european plastic pipes and fittings association (teppfa) conducted lcas for different plastic pipe systems, in each case the lcas were compared against a traditional material. the report released by georg fischer piping system included four plastic pipe systems, which were compared against ductile iron and copper pipe systems. the report highlighted that the superiority of the plastic system, evident by the gwp and ozone depletion potential (odp) findings. the plastic pipes performed at least 60% better than the traditional materials in both impact categories. the key objective of this paper is the integration of bim with lca for the realization of the most sustainable building design. within this context, two case studies for the production of water supply systems comprised of different materials are implemented. bim is employed for the modelling of the water supply systems, while lca is implemented for the comparison of a modern vernetztes polyethylen (vpe) water supply system against two systems made from traditional materials, namely steel and copper. the results of this work lead to some significant conclusions regarding the benefits of bim and lca integration for the increase of the level of sustainability of the built environment. the building information model design of the water supply system under investigation is presented in fig.1, while table 1 presents the design characteristics, employed for the implementation of the lca, for each of the designs; vpe water supply system (d1), steel water supply system (d2), copper water supply system (d3). to this end, dds-cad was employed to model the design of the water supply system, while gabi software (version 6) adopted the model to implement a ‘cradle-to-gate’ lca based on the principles described in the iso 14040 standard (iso, 2006) for the investigation of its environmental performance and the definition of its level of sustainability throughout its life cycle. it is also worth mentioning that the environmental impacts during the installation, operational, and endoflife phases for the water supply systems under examination were not considered in this lca. accordingly, any potential impacts during these lifecycle phases were found outside the defined system boundaries. the system boundaries of this work are illustrated in fig.2, while the functional unit of the system has been defined as one unit of water supply system, approximately 120 kg of piping. for the purposes of this study, the international reference life cycle data system (ilcd) recommendations methodology was employed. the specific methodology generates a set of 13 impact categories, of which the following were chosen to be investigated in this paper: _ global warming potential (gwp 100 years), _ acidification potential (ap), _ ozone layer depletion potential (odp, steady state), _ photochemical ozone creation potential (pocp) _ resource depletion, mineral, fossil, and renewable (adp elements & fossil). the sustainability of the vpe water supply system was assessed against two traditional materials’ systems, steel and copper. table 1 presents the design characteristics of the water supply systems that are constant across all three designs, as well as the ones that were altered for each of the designs. methods 31 journal of sustainable architecture and civil engineering 2015/4/13 table 1 design characteristics of water supply systems designs product number product description quantity unit d1, d2, d3 th353/2504 hot water tank water heater 250 litre 1 pcs zp150/915 pipe insulation 9x15 mm gray insulation thickness 9 mm 72,12 m zp150/918 pipe insulation 9x18 mm gray insulation thickness 9 mm 13,029 m zp150/922 pipe insulation 9x22 mm gray insulation thickness 9 mm 31,713 m zp150/928 pipe insulation 9x28 mm gray insulation thickness 9 mm 2,565 m ta340/04 shut off valve dn 15 without discharge valve 1 pcs ta340/05 shut off valve dn 20 without discharge valve 2 pcs zpum25 circulating pump dn 25 sleeve 1 pcs ba-20120605-076 shower tub round 800x120 mm 5 pcs bin649 standing position bidet 1 pcs bsn40/50 hand basin 500x375 mm 2 pcs sw-20120605-032 shower with single lever mixer 5 pcs sw-20120605-049 bidet mixer single lever 1 pcs wc059 wall wc wash down with on top cistern 2 pcs wc330 urinal flush backwards 1 pcs d1 ss2001/707 vpe system pipe length 6 m dvgw 15x1 mm 72,12 m ss2001/710 vpe system pipe length 6 m dvgw 18x1 mm 13,029 m ss2001/712 vpe system pipe length 6 m dvgw 22x1,2 mm 31,713 m ss2001/714 vpe system pipe length 6 m dvgw 28x1,2 mm 2,565 m d2 ss091209020 steel pipe welded dn 15 (1/2”)din en 10220 raw (black) 73,203 m ss091209021 steel pipe welded dn 20 (3/4”)din en 10220 raw (black) 45,971 m ss091209022 steel pipe welded dn 25 (1”)din en 10220 raw (black) 0,61 m d3 ss091209003 copper pipes length 5 m 15x1 mm 61,541 m ss091209004 copper pipes length 5 m 18x1 mm 24,827 m ss091209005 copper pipes length 5 m 22x1 mm 31,991 m ss091209006 copper pipes length 5 m 28x1,5 mm 2,636 m journal of sustainable architecture and civil engineering 2015/4/13 32 the lci involves with the data recording of the ‘cradle-to-gate’ input resources and energy requirements, as well as the output impacts, in terms of environmental degradation, associated with the raw materials and the water supply system production. in particular, the dataset for the polyethylene water supply system includes all relevant process steps and technologies over the supply chain, mainly based on industry data, complemented by secondary data. the lci of the vpe water supply system under investigation is given in table 4. the lci of the steel water supply system covers the raw materials extraction and processing for its manufacturing; the inputs of table 5 relate to all raw material inputs, including steel scrap, energy, water, and transport, while the outputs include steel and other co-products, emissions to air, water and land. it is worth noting that the lci does not include a credit for recycling of steel at end of life or a burden for steel scrap input during manufacturing. the dataset for the copper water supply system covers all relevant process steps and technologies over its supply chain, encompassing mining and processing (concentrate production), hydrometallurgy (leaching, solvent extraction, electro winning) and pyrometallurgy (smelting, converting, fire refining, electrolytic refining). similarly to the rest of the investigated systems, the lca does not provide credit for the copper scrap after the use of the product (gabi database). the lci of the copper water supply system under investigation is given in table 6. fig. 1 building information modelling (bim) of water supply system under investigation fig. 2 system boundaries of the life cycle assessment (lca) conducted in this work life cycle inventory (lci) 33 journal of sustainable architecture and civil engineering 2015/4/13 the results of the lcia, illustrated in fig. 5, indicate the vpe water supply system production is superior in terms of sustainability compared to the investigated traditional materials. this can be mainly attributed to the fact that the pipes used to produce the vpe system utilize recovered materials and energy (table 2). given that climate change has evolved into an influential factor in the decisionmaking of both the public and the private sector, it probably provides the strongest indication for the environmental performance and sustainability level of a product or a system to the nonscientific communities. the gwp of the vpe water supply system is 17.7 kg co2equivalent, against the steel and copper’s, 128.and 151.3 kg co2equivalent, respectively. thus regarding the gwp impact category, the vpe water supply system performs 86.3% better than the steel system, and 88.3% than the copper water supply system. however, in the case of ozone depletion, an environmental impact strongly associated with policy regulations and influences political action, the picture is very different. the vpe water supply system is indicated to have no contribution to the ozone depletion, while copper has negligible impact compared to the steel water supply system. in particular, the impact of the copper’s system is 0.3 kg of r-11 equivalent, while the steel’s reached the 9.3 kg of r-11 equivalent. the impact categories associated with tropospheric processes and pollution, namely photochemical ozone formation and acidification, have also been chosen for analysis in this paper in view of the fact that they directly affect the human health. pocp and ap illustrate comparable results in the lcia. the performance of the vpe water supply system for the photochemical ozone formation impact category is 0.04 kg nmvoc equiv. and 0.08 mole of h+ equiv. for the acidification category. accordingly, the specific system’s performance compared to the steel system is 79.0% better for the pocp and 75.0% for the ap categories. furthermore, in comparison to the copper water supply system, the plastic system performs approximately 89.0% in both tropospheric pollutionrelated impact categories. regarding the adp category, closely related to the carbon emissions and the depletion of nonrenewable energy resources, the vpe system is also evidently superior to the competing systems employing traditional materials. more specifically, the impact of the plastic system in this impact category is minimalat 0.005 kg of sbequivalent, performing 98.4% and 99.9% better than the steel and copper systems, 0.32 and 6.36 kg of sbequivalent respectively, which utilize both primary and waste materials for their production. furthermore, the comparison of the vpe water supply system against the traditional materials’ systems in terms of lifecycle nonrenewable energy consumption and carbon dioxide emissions is also indicative of their environmental performance. the nonrenewable energy consumption of the plastic system is 600 mj, whereas for the steel and copper the specific value rises to 1360 mj and 1890 mj, respectively. as a result, the conventional water supply systems are observed to be 55.9% for the steel system and 68.3% for the copper system more fossilfuelled energy intensive than the vpe system. additionally, the results of the analysis also indicated that the production of the vpe system emits 14.1 kg of co2, approximately the one tenth in comparison to the production of a water supply system utilizing a traditional material121 kg of co2 and 141 kg of co2 for the steel and copper systems, respectively. the findings of this work are comparable with findings of the report released by georg fischer piping system. in the specific report, the gwp resulting from the production of the pe piping system was found to be around 7 kg co2-equiv, whereas the odp around 1×10-7 kg cfc11-equiv. the deviation in the results can partly be attributed in the variation of the functional units of the two studies. the functional unit of the georg fischer report was defined as the underground transportation of drinking water, over a distance of 100m, from the exit of the water plant to the water meter of the building, by a typical public european pe pipe water distribution system over its complete life cycle of 100 years, calculated per year. however, this work has set its functional unit to one unit of water supply system, which totals approximately to 120m of piping. it is also noteworthy that the european union public procurement directive (euppd), 2013 recommends the employment of bim for construction and projection contracts. accordingly, an inresults and discussion journal of sustainable architecture and civil engineering 2015/4/13 34 d1: vpe water supply system d2: steel water supply system d3: copper water supply system process unit inputs amount inputs amount inputs amount production kg materials materials materials municipal waste 0.118 steel scrap (st) 6.28 reverts 21-40 % cu 0.0559 copper slag concentrate 0.0796 steel scrap (st) 0.0849 scrap (71-95 % cu) 0.256 scrap (20-40 % cu) 0.328 cu scrap (purchased) 16.3 copper scrap (>95% cu content) 30.9 mj energy thermal energy (recovered) -10 industrial waste (incineration) 0.627 outputs outputs outputs production kg materials materials materials wooden pallet (euro) 1.25e-9 wooden pallet (euro) 7.47e-13 waste rock 580 wood 0.00633 wood 3.18e-6 used emulsion 0.357 waste paper 0.00662 waste paper 1.07e-11 tailings (deposited) 9.04 waste 0.0103 waste for recovery 5.11 slag 1.9 toxic chemicals 0.018 waste 0.00943 radioactive tailings 0.0738 tailings 0.000507 steel welded pipe 50.5 overburden (deposited) 727 slag 0.144 sludge (from processing) 0.000631 medium radioactive wastes 0.000725 production residues 0.0321 sludge 0.00432 low radioactive wastes 0.00148 polyethylene tube (pe) 7.12 slag (mn 6,5%) 0.456 high radioactive wastes 0.0000103 plastic 0.0347 slag (iron plate production) 0.0216 gypsum) 0.21 packaging waste (plastic) 3.7e-11 slag (containing precious metals) 5.02e-5 furnace dust 1.88 packaging waste (metal) 0.000857 slag (waste for recovery) 0.00728 furnace ashes 22.7 overburden (deposited) 0.224 slag (hazardous waste) 0.00172 filter dust 0.00423 table 2 life cycle inventory (lci) of water supply systems under investigation (gabi database) 35 journal of sustainable architecture and civil engineering 2015/4/13 process unit outputs amount outputs outputs amount production kg materials materials materials organic waste 3.56e-6 sinter/ pellet dust 3.58e-6 dross 0.0561 municipal waste -0.111 rolling tinder 1.47e-18 copper tube 68.6 mineral waste 0.00943 rolling gravel 0.0405 converter slag 4.56 inert chemical waste 0.00516 red mud (dry) 0.208 converter dust 0.3 industrial waste for municipal disposal -0.0164 production residues 1.03e-10 black acid 0.0247 incineration good 0.00632 plastic 2.81e-5 anode sludge 0.0767 demolition waste (deposited) 8.6e-8 pickled hot rolled coil sludge 0.000488 anode scrap 0.512 chemicals 0.0236 overburden (deposited) 239 acid slime 0.0584 non hazardous non organic waste for disposal 1.72 neutralized residues 0.00105 natrium oxide 0.0024 mineral waste (hazardous waste for disposal) 0.603 mineral waste (consumer waste) 0.00993 hot rolling sludge 1.17 hazardous waste 0.00566 hazardous organic waste for disposal 0.000113 hazardous non organic waste for disposal 0.199 gypsum (fgd) 0.00555 gypsum 0.0114 dross (fines) 0.000511 cryolite 0.000472 cooling water -0.00747 cold rolling emulsion treatment sludge 4.91e-5 chemicals 0.0000102 bof slag 0.127 bof gas dust 0.0494 aluminium scrap 5.25e-5 journal of sustainable architecture and civil engineering 2015/4/13 36 creasing number of construction companies are implementing bim to increase the quality, as well as the productivity of their work. the significance of supplementing bim with lca is found in the attainment of the objective of achieving the most sustainable building projects in practice. for that reason, scientific findings and recommendations are valuable in this field. fig. 5 life cycle impact assessment (lcia) of investigated water supply systems global warming potential (gwp) [kg co2-equiv.] ozone depletion potential (odp) [kg r11-equiv.] photochemical ozone creation potential (pocp) [kg nmvoc equiv.] acidification potential (ap) [mole of h+ equiv.] resource depletion, mineral, fossil, and renewable (adp elements & fossils) [kg sb-equiv.] 37 journal of sustainable architecture and civil engineering 2015/4/13 this work demonstrated the benefits that arise from the synergy of two wellestablished methodologies, bim and lca. the lca that for the definition of the level of sustainability and environmental performance of the modern vpe system against the traditional steel and copper water supply systems was conducted according to the design of the specific systems using sophisticated bim tool. the results of the lca revealed the superiority of the production of the modern vpe water supply system in terms of sustainability compared to the investigated traditional materials. the vpe water supply system performed 86.3% better than the steel system, and 88.3% than the copper water supply system in the gwp impact category, and also indicated that its production does not contribute ozone depletion. additionally, it was illustrated that it achieves a reduction in the tropospheric pollutionrelated potential, photochemical ozone formation and acidification, by least 74.4% in comparison to the production of conventional water supply systems. the impact of a vpe system’s production is also negligible on the natural element and fossil resources, in contrary to the production of a copper system, which was observed to be the less sustainable one across the majority of the investigated impact categories. the advantages from integrating of bim and lca have been demonstrated through the implementation of this case study. evidently, this synergy cannot only point towards the most sustainable designs from an early stage in the construction project, but also provides the opportunity to several different expertise and stakeholders to collaborate for the maximization of the desirable impacts. conclusions ajayi so, oyedele lo, ceranic b, gallanagh m, kadiri ko. life cycle environmental performance of material specification: a bim-enhanced comparative assessment. international journal of sustainable building technology and urban development 2015:6(1):14-24. http://dx.doi.org/10.1080/209376 1x.2015.1006708 antón la, díaz j. integration of life cycle assessment in a bim environment. procedia engineering 2014;85:26-32. http://dx.doi.org/10.1016/j.proeng.2014.10.525 brás a, gomes v. lca implementation in the selection of thermal enhanced mortars for energetic rehabilitation of school buildings. energy and buildings 2015;92:1-9. http://dx.doi.org/10.1016/j.enbuild.2015.01.007 cabeza lf, rincón l, vilariño v, pérez g, castell a life cycle assessment (lca) of phase change materials (pcms) used in buildings. in: eco-efficient construction and building materials, pacheco-torgal f, cabeza lf, labrincha j, de magalhães a (eds). woodhead publishing, 2014b: 287-310. http://dx. doi.org/10.1533/9780857097729.2.287 cabeza lf, castell and g. pérez. life cycle assessment(lca)and life cycle energy analysis (lcea) of buildings and the building sector: a review. renewable and sustainable energy reviews 2014;29: 394– 416. http://dx.doi.org/10.1016/j.rser.2013.08.037 ding l, zhou y, akinci b. building information modeling (bim) application framework: the process of expanding from 3d to computable nd. automation in construction 2014;46:82-93. http://dx.doi. org/10.1016/j.autcon.2014.04.009 dylewski r, adamczyk j. life cycle assessment (lca) of building thermal insulation materials. in: eco-efficient construction and building materials, pacheco-torgal f, cabeza lf, labrincha j, de magalhães a (eds). woodhead publishing, 2014:267286. http://dx.doi.org/10.1533/9780857097729.2.267 en iso 14040: 2006: environmental management life cycle assessment – principles and framework. european commission. directive 2010/31/ec of the european parliament and of the council of 19 may 2010 on the energy performance of buildings (recast). gabi (version 6). gabi software: pe international, 2015. available from:http://www.gabi-software. com/international/index/ georg fischer piping systems. life cycle assessments of plastic pipe systems in the field of utility and building technology. available from: http:// www.gfps.com/content/dam/gfps/master%20 content/documents/en/gfps_sustainability_summary_teppfa_lca_121001.pdf guardigli l, monari f, bragadin ma. assessing environmental impact of green buildings through lca methods: a comparison between reinforced concrete and wood structures in the european context. procedia engineering 2011;21:1199-1206. http:// dx.doi.org/10.1016/j.proeng.2011.11.2131 ham y, golparvar-fard m. mapping actual thermal properties to building elements in gbxml-based bim for reliable building energy performance modelling. automation in construction 2015;49(part b):214-224. iddon cr, firth sk. embodied and operational energy for new-build housing: a case study of construction methods in the uk. energy and buildings references journal of sustainable architecture and civil engineering 2015/4/13 38 2013;67:479-488. http://dx.doi.org/10.1016/j.enbuild.2013.08.041 jung y, joo m. building information modelling (bim) framework for practical implementation. automation in construction 2011;20(2):126-133. http://dx. doi.org/10.1016/j.autcon.2010.09.010 kulahcioglu t, dang j, toklu c. a 3d analyzer for bim-enabled life cycle assessment of the whole process of construction. hvac&r research 2012;18(1-2):283-293. ladenhauf d, battisti k, berndt r, eggeling e, fellner dw, gratzl-michlmair m, ullrich t. computational geometry in the context of building information modeling, energy and buildings 2015, available online 4 march, http://dx.doi.org/10.1016/j. enbuild.2015.02.056 marinković sb. life cycle assessment (lca) aspects of concrete. in: woodhead publishing series in civil and structural engineering, pacheco-torgal, f, jalali s, labrincha j, john vm (eds.). woodhead publishing, 2013:45-80. http://dx.doi. org/10.1533/9780857098993.1.45 national institute of building sciences. national building information model standard project committee. call for papers and case studies bim academic symposium, in conjunction with building innovation 2014 the national institute of building sciences conference & expo. 2014. available from: http://c.ymcdn.com/sites/www.nibs.org/ resource/resmgr/conference2014/bi20140110_ bsa_proceedings.pdf?hhsearchterms=%22earliest+and+conception+and+demolition%22 pargana n, pinheiro md, silvestre jd, de brito j. comparative environmental life cycle assessment of thermal insulation materials of buildings. energy and buildings 2014;82:466-481. http://dx.doi. org/10.1016/j.enbuild.2014.05.057 rønning a, brekke a. life cycle assessment (lca) of the building sector: strengths and weaknesses. in: eco-efficient construction and building materials, pacheco-torgal f, cabeza lf, labrincha j, de magalhães a (eds). woodhead publishing, 2014:6383. http://dx.doi.org/10.1533/9780857097729.1.63 salazar j. life cycle assessment (lca) of windows and window materials. in: eco-efficient construction and building materials, pacheco-torgal f, cabeza lf, labrincha j, de magalhães a (eds). woodhead publishing, 2014:502-527. http://dx.doi. org/10.1533/9780857097729.3.502 sathre r, gonzález-garcía s. life cycle assessment (lca) of wood-based building materials. in: eco-efficient construction and building materials, pacheco-torgal f, cabeza lf, labrincha j, de magalhães a (eds). woodhead publishing, 2014:311-337. http://dx.doi.org/10.1533/9780857097729.2.311 shoubi mv, bagchi a, barough as. reducing the operational energy demand in buildings using building information modeling tools and sustainability approaches. ain shams engineering journal 2015;6(1):41-55. http://dx.doi.org/10.1016/j. asej.2014.09.006 wang e, shen z, barryman c. a building lca case study using autodesk ecotect and bim model. in: 47th associated schools of construction (asc ) annual international conference proceedings: construction systems: papers in construction management, 2011. yuan y, yuan j. the theory and framework of integration design of building consumption efficiency based on bim. procedia engineering 2011;15:5323-5327. http://dx.doi.org/10.1016/j.proeng.2011.08.987 paris a. fokaides dr. lecturer frederick university, cyprus, school of enginee ring and applied sciences main research area computational and experimental building physics, sustainable energy technologies, renewable energy sources address 7, frederickou str., 1036, nicosia, cyprus tel. +35722394394 e-mail: eng.fp@frederick. ac.cy angeliki kylili research associate frederick university, cyprus, school of engineering and applied sciences main research area energy efficiency of buildings, sustainable energy resources, lca address 7, frederickou str., 1036, nicosia, cyprus tel. +35722394394 e-mail: res.ka@ frederick.ac.cy juozas vaiciunas dr. lecturer kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area water supply and disposal systems, hydronic performance of hvac systems, structural stability of buildings address studentu st. 48, lt-44403, kaunas, lithuania tel. +370-615-56760 e-mail: juozas.vaiciunas@ktu.lt lina seduikyte assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area indoor environment, lca, energy efficiency of buildings address studentu st. 48, lt-44403, kaunas, lithuania tel. +370 37 350453 e-mail: lina.seduikyte@ ktu.lt about the authors journal of sustainable architecture and civil engineering 2017/3/20 14 *corresponding author: atamewaneugene@gmail.com sustainable low-income housing and practicable minimum design standards in bayelsa state, nigeria http://dx.doi.org/10.5755/j01.sace.20.3.18208 eugene ehimatie atamewan* cross river university of technology, department of architecture, calabar, nigeria remi ebenezer olagunju federal university of technology, school of environmental technology, department of architecture, minna, nigeria received 2017/05/19 accepted after revision 2017/09/15 journal of sustainable architecture and civil engineering vol. 3 / no. 20 / 2017 pp. 14-24 doi 10.5755/j01.sace.20.3.18208 © kaunas university of technology sustainable lowincome housing and practicable minimum design standards in bayelsa state, nigeria jsace 3/20 introduction the sustainability of low-income housing in nigerian cities vis-a-vis building regulation/minimum design standards is discussed in this paper. thus, the papers appraised the practicability of the existing minimum housing standards regarded as a borrowed idea in relation to the socio-economic realities of the low-income urban dwellers. data collection involved both qualitative and qualitative data from the private owners and rentals /users of low-income housing available in the study area. this study employs non-probability sampling designs which are a combination of purposive and expert sampling techniques. sample frame of 20 housing units in the low-income neighbourhood and respondents were selected for in-depth study and interview, while only 15 key informants were interviewed. this was complemented with 1440 questionnaires distributed across the low-income residential neighbourhoods. the quantitative data were analysed using both simple descriptive and inferential statistics; this was done using the minitab statistical package (msp), version 14 and statistical package for social sciences (spss) version 22 which involved the calculation of the chi-square test while the qualitative data were analyzed using content analysis from where themes and conclusions were drawn. findings show that the existing housing standards are not realistic and the lowincome urban dwellers cannot afford the conventional standard houses because it requires high construction cost, building material and labour due to their poverty level. the paper further re-developed a proposed minimum housing standard which is practical and affordable to the urban poor. finally, it is recommended that housing standards should be based on the concept of “low and upgradable” which is relaxed and flexible for the low-income group while also encouraging incremental housing approach including the provision of basic infrastructure services by the government to enhance liveability. keywords: housing, minimum standard, low-income, liveability, sustainable, upgradable. the complicated problems of housing shortage especially housing for the low-income as well as the rapid development of substandard urban housing in developing countries like nigeria goes beyond mere lack of funds, construction of mass housing or construction techniques but mainly due to inappropriate planning practice, regulations and unrealistic housing design standards applicable across the countries (fin-mark trust, 2010). according to bourennane, (2007), due to failure of several housing delivery strategies some governments of developing countries have adopted new enabling regulations that include relaxation of development control codes and appropriate housing standards. this enabling concept means flexibility and relaxation of the codes so that the low-income households can use their resources and energy to construct houses of their choice. 15 journal of sustainable architecture and civil engineering 2017/3/20 most cities in developing countries including nigeria are dominated by the low-income populace; therefore any housing policy that does not consider the low-income group is bound to fail. this is why the existing minimum housing standards and regulations which are essentially foreign and imported are very unrealistic and may certainly not have direct relevance to nigerian environment and should be reviewed to accommodate the larger population called the low income group who are believed to be poor. meanwhile, survey of awofeso (2010), olotuah and aiyetan (2006), federal government of nigeria (fgn, 2006) shows that over 70% of heads of household in the city are low income and earn ₦216,000 per annum (based on national minimum wages of ₦18,000) or less, ₦70,000 (by definition of low income in nigeria) and presently over 90% of nigerians within the low-income range cannot afford decent or standard housing even if they saved 100% of their income for a period of ten years. the implication is that the poor could only wish to own a house built to meet minimum standard and regulations. there are still diverse views as to the question of what constitutes housing standard. the first is that there should be a minimum housing standards for all categories of income groups, the second advocates an total maximum standards for all irrespective of income level which seem segregational making cities livable only by the few wealthy ones (bramley et al., 1995). the third opinion which forms the core of this paper is the one that advocate relaxed and socially acceptable standards for low income housing otherwise referred to as “low and upgradable housing”. their argument is based on the fact that housing must be seen as a continuous incremental process, and not as a physical artifact designed and built at one moment in time (turner, 1976; burgess, 1982; hamdi, 1991). undoubtedly, the vast low-income populace across cities in nigeria can barely eat three square meals a day and are living below the poverty line, hence cannot afford to construct houses with the prevailing design standard on their own or live in standard built houses as tenants due to high rents charged by developers. this is why this study intends to develop practical minimum design standards for low-income residential housing in bayelsa state, nigeria. literature review theory of minimum housing standards and space for low income. the subject of design standards in housing is a complicated issue that is all-encompassing, cutting across all facet of the urbanization process, from theoretical explanations of function and satisfactoriness, to practical consideration in housing construction and servicing. thus, differences exist in opinions among professionals and policy makers as to what should constitute an acceptable and practicable minimum housing standards. however, for housing to be termed affordable, both to the state and to the low income urban dwellers, the capability of the poor to pay their own way must be reflected in the application of realistic standards (rsa, 1994). a critical look at the current national building code and housing standards across the states of nigeria shows a complete adoption from the developed nations especially britain which is not practicable here in nigeria and other developing nations of the world. thus, by this standard, most of the houses in our cities including the government reserved quarters (gra) do not qualify as habitable houses. this is largely because these “borrowed” standards require high construction techniques and are costly for the poor low-income populace who can hardly afford the requirements (jinadu, 2007). this is why it is very difficult or almost impossible for the poor to observe and comply with the established standards. mabogunje et al. (1978) opined that standards in the developed countries evolved to protect the low-income groups of the country against the sub-standard buildings produced for them by exploitative landlords, such standards seems to protect the wealthier and educated against the incursion of lower levels of dwellings in the developing countries. however, promoters of relaxed and socially acceptable standards for low income housing are of the opinion that the low income housing should operate the concept of “low and upgradable housjournal of sustainable architecture and civil engineering 2017/3/20 16 ing”. this means, they should be allowed to produce initial lower standard housing using artesian production techniques and technology and over time make improvements to the housing to bring it up to socially acceptable standards. their argument is based on the use-values of houses in conformity with socially acceptable standards, which are permanently redefined in the context of an on-going social struggle (walker, 2001). consequently, turner (1992) opined that housing seen as deficit and defined by standards that the majority of the populace cannot afford and which the city agencies or government cannot supply in large quantities, is practice of depression. however, the relaxed standard advocated does not in any way suggest that certain indisputable minimum standards especially those that promote health and safety and endanger life should not be clearly considered, rather they should be strongly preserved and enforced while others remain very flexible (harber, 1995). this will further engender social inclusion, promote healthy living and ultimately promote longevity. this is in line with the characteristics of housing standards according to the united nations (1974), which stipulates that effective standards: a are normative propositions, which imply and express what is desirable rather than what exists; b are feasible, that is, the required performance can be expected from those for whom the standards are made; c contain the promise and prediction of sanctions, that is, reward for compliance and penalty for non compliance; d originate from recognized authorities that are capable of enforcing them. accordingly, turner (1992) opined that the imposition of modern minimum standards on informal housing occupied by the low income group is an assault on the traditional function of housing as a source of social and economic security and mobility maintaining that standards should be proscriptive in nature, and related to minimum performance requirements. nevertheless, it is imperative that satisfactory agreement be reached regarding opinion of standards within realistic affordability and resource constraints, so as to ensure a sustainable housing process that will satisfy the basic needs of the low income urban dwellers. theory of enabling housing strategies. housing problems in cities of developing nations including nigeria will have to be determined and solved within the framework of an all-inclusive urbanization strategy that is fair and objective in its response to all income levels in housing concerns and paying attention on the management of urban areas. it should be acknowledged that informal housing, being occupied by the low income on sites with basic services and neighbourhood facilities, forms the basis of a long-lasting process of rapid urbanization (gilson, 1990). one basic problem of low income housing development in most countries of developing nation is the unfavourable official housing policy that these so called informal settlements should be pulled down while formal minimum standard housing units in ‟permanent‟ building materials produced according to strictly regulated urban plans replaces them. this model has never been successful in developing countries. enabling strategy simply means the full involvement of low income urban dwellers in solving their housing problem through self-help construction methods with gradual improvement process with the government removing obstacles through relaxed and flexible land tenure, plot sizes and space design standards (vestbro, 2007). this idea was developed by the british architect john turner describing it as the survival strategy of the poor to have a roof over their head in cities. to him affordability is more important to the low income than standards. the enabling strategy is not in any way opposed to standards as professional guidance but such standards should be relaxed for the low income city dwellers. 17 journal of sustainable architecture and civil engineering 2017/3/20 the summary of turner’s theory of enabling strategy is that low-income urban dwellers can usually not afford standards such as several rooms, durable building materials, drainage, paved roads or clean water from the start. the low-income person needs a job which makes it compulsory for him to stay in the city centre within walking distance to where the jobs are available or where customers are found for small-scale business since the poor person cannot afford transport costs. as the poor gets regular and better income, priorities change and standards can now be discussed (turner, 1992). data used in this study were collected from multiple sources. the sources are both primary and secondary. the data sources used in this study were in-depth interviews, physical observation, recording of artefacts, use of sketches, photographs, use of questionnaires and document reviews which include working papers, housing programme brochures, government’s official documents especially the housing policy of bayelsa state in particular and nigeria in general. this study employs non-probability sampling designs which are a combination of purposive and expert sampling techniques. sample frame of 20 housing units in the low-income neighbourhood and respondents were selected for in-depth study and interview, while about 15 key informants were interviewed. this was complemented with 1440 questionnaires distributed across the low-income residential neighbourhood in the study areas. the data collection combined qualitative and quantitative methods. the quantitative data were obtained using questionnaires responses from respondent’s rating on the standard of the dwelling unit in the low-income residential neighbourhood using a 5-ponit likert scale where 1 very poor standard, 2 poor standard, 3 fair, 4 good standard, 5 very good standard. the data were analyzed using inferential statistics; this was done using the minitab statistical package (msp), version 14 and statistical package for social sciences (spss) version 22 which involved the calculation of the chi-square test while the qualitative data were analyzed using content analysis from where theme and conclusions were drawn. the quantitative data provided this study with essential basic statistics, while qualitative data enriched the research discussion developing a better context for interpreting the results from statistical data methodology fig. 1 bayelsa state, nigeria. source: bmict (2002) the study area. bayelsa state was created in october 1, 1996 out of the old rivers state, in the core niger delta region. the state is bounded on the east by rivers state, on the west by delta state and south by the atlantic ocean. the state lies between latitude 4° 15’ n and 5o 23’ s and longitude 5° 22’ w and 6° 45’ e. it has an estimated population of 1 998 349 (2005 census) with yenagoa as the state capital (bmict, 2002). journal of sustainable architecture and civil engineering 2017/3/20 18 overall housing standards analysis in the analysis of the housing standards, which is one of the objectives and core of the study, eighteen (18) housing units and housing services attributes were used for the analysis. respondents across the study areas were asked to rate the standards of their housing units using a 5 point linkert scale rating of very poor standard (1), poor standard (2), fair standard (3), good standard (4) and very good standard (5) respectively. the study shows that 33.9% of the respondents rated the housing units as poor standard, 26.3% agreed it was very poor standard, 21.6% rated it as fair (neither good nor poor) standard, 10.8% claimed it was good standard while only 7.4% agrees it was very good standard. this implies that majority of the respondents (60.2%) claimed that the standards was poor. discussion and findings fig. 2 overall housing standards analysis. source: authors’ survey (2016) housing units as poor standard, 26.3% agreed it was very poor standard, 21.6% rated it as fair (neither good nor poor) standard, 10.8% claimed it was good standard while only 7.4% agrees it was very good standard. this implies that majority of the respondents (60.2%) claimed that the standards was poor. fig. 2. overall housing standards analysis. source: authors’ survey (2016) 3.2. analysis of standards of selected housing sub-components the analysis of the floor areas of the investigated housing units (figure 3) in relation to the existing minimum housing standards were made possible with the help of research assistants who evaluated the housing units by carrying out direct physical measurement and sketches as most of the respondents lacked the knowledge of what was being investigated. in most cases, the content of the questionnaires was interpreted to respondents for easy responses. standard of size of living /dining room respondents were asked to rate the standard of the size of their living / dining rooms. this was based on the minimum housing standard that is operational at the moment. thus, for the living room, the space requirement used was 12 m2 as the basic minimum area while the dining room was 7.5m2. the results showed a larger proportion of the respondents (40.3%) rated them as poor. 27.4% of the respondents rated it as very poor. also, 21.6% say the standard is fair while 6.3% say it is good and only 4.3% rated it as very good. the implication here is that very high proportion of the respondents (67.7%) is of the opinion that standard of the living / dining room in their apartment is poor. dining rooms were non-existent in the houses studied in detail but during the questionnaire administration, it was discovered that in less than 5% of houses that had dining room, its floor areas were less than 7.5 m2 minimum standards required. standard of size of bedrooms the minimum space requirement for a bedroom used for this analysis based on the current standard is 13 m2. hence, on the standard rating of the size of the bedroom, 32.1% rated it as poor; while 26.9% respondents say the standard is fair. 23.3% rated it as very poor. the percentage of those who rated the standard as good and very good was 10.6% and 7.1% respectively. 26,30% 33,90% 21,60% 10,80% 7,40% 0,00% 5,00% 10,00% 15,00% 20,00% 25,00% 30,00% 35,00% 40,00% very poor poor fair good very good housing standards analysis analysis of standards of selected housing sub-components the analysis of the floor areas of the investigated housing units (fig. 3) in relation to the existing minimum housing standards were made possible with the help of research assistants who evaluated the housing units by carrying out direct physical measurement and sketches as most of the respondents lacked the knowledge of what was being investigated. in most cases, the content of the questionnaires was interpreted to respondents for easy responses. standard of size of living /dining room respondents were asked to rate the standard of the size of their living / dining rooms. this was based on the minimum housing standard that is operational at the moment. thus, for the living room, the space requirement used was 12 m2 as the basic minimum area while the dining room was 7.5m2. the results showed a larger proportion of the respondents (40.3%) rated them as poor. 27.4% of the respondents rated it as very poor. also, 21.6% say the standard is fair while 6.3% say it is good and only 4.3% rated it as very good. the implication here is that very high proportion of the respondents (67.7%) is of the opinion that standard of the living / dining room in their apartment is poor. dining rooms were non-existent in the houses studied in detail but during the questionnaire administration, it was discovered that in less than 5% of houses that had dining room, its floor areas were less than 7.5 m2 minimum standards required. standard of size of bedrooms the minimum space requirement for a bedroom used for this analysis based on the current standard is 13 m2. hence, on the standard rating of the size of the bedroom, 32.1% rated it as poor; while 26.9% respondents say the standard is fair. 23.3% rated it as very poor. the percentage of 19 journal of sustainable architecture and civil engineering 2017/3/20 those who rated the standard as good and very good was 10.6% and 7.1% respectively. standard of kitchen and store the basic minimum requirements for a kitchen in residential bungalow used for the analysis are 6 m2, while that of a store is 3 m2. respondents rated the standard of their cooking and storage spaces as follows: 45.9% say it is very poor, 31.6% say it is poor; while 9.0% rated it as fair, 7.7% and 6.5% rated it as good and very good standards. this is an indication that about half of the respondents rated their kitchen and stores as very poor and put together, very high proportion of respondents (77.5%) rated the standard as poor. standard of security measure respondents’ standard rating of the security measures in their dwelling units reveals that a higher percent (33.2%) say it is fair; 22.9% say it is poor; 20.5% say it is good, while 13.9% agree it is very good and only 9.5% say it is very poor. this measurement was against the inclusion of burglary proof and type of doors at the external of the housing units. these show that on the average the standard of the security measures is fair tilting towards good. standard of level of privacy the level of privacy in the housing units was measured based on the number of persons living in a room and number of persons sharing facilities such as toilets and bathrooms. the standard rating by respondents on the level of privacy in their dwelling units show that larger proportion of 39.3% describe it as poor, 25.3% say it is very poor, 19.6% say it is fair; while 9.6% and 6.2% rated it as good and very good respectively. this reveals that respondents experience a very poor level of privacy in their dwelling units. respondents average monthly income the study in table 1 shows that majority of the respondents (36.6%) earn an average monthly income of between ₦31 000 and ₦50 000. the respondents who earn between ₦16 000 and ₦30 000 stood at 24.2%. this was closely followed by respondents who earn between ₦6 000 and ₦15 000 which is 22.5%. those fig. 3 some of the housing units studied in the study areas. source: authors’ survey, 2016 journal of sustainable architecture and civil engineering 2017/3/20 20 who earn between ₦51 000 and ₦70 000 were put at 11.2%. a small proportion of the respondents (5.5%) earns above ₦71 000, while the 0% proportion of respondents earns below ₦5 000. respondents affordability of the housing units the respondents were also asked to evaluate the cost of acquiring or renting their housing units. the evaluation inditable 1 respondents average monthly income income percentage (%) frequency 31000 – 50000 naira 36.6% 474 16000 – 30000 naira 24.2% 313 6000 – 15000 naira 22.5% 291 51000 – 70000 naira 11.2% 145 71000 and above 5.5% 71 total 100% 1294 ces were from very unaffordable, unaffordable, affordable to very affordable. greater proportion of the respondents 71.4% indicated that cost was unaffordable. this was followed by 13.7% respondents who agreed the cost of housing was very unaffordable, this was closely followed by 14.9% respondents who claimed that the cost of housing was affordable while very affordable had 0% respondent. this is an indication that the low-income urban dwellers in the study areas see the cost of acquiring and or renting their housing units as generally unaffordable. fig. 4 respondents level of affordability. source: authors’ survey (2016) summary of findings the study also evaluated the standards of the components of the housing unit as well as the provision of infrastructure services in the neighbourhood of the study areas. on the standard of the size of living / dining room, larger proportion (67.7%) of respondents rated it as poor, while the standard of the bedroom was rated by larger proportion (55.4%) as poor about 26.9% rated it fair (neither good standard nor poor standard). the study also shows that for the standard of kitchen / store, very high proportion of respondents (77.5%) rated the standard as poor. this is not surprising as most of the dwelling units surveyed had their kitchen outside the building and constructed with waste woods or aluminum roofing sheets or simply absent in some other cases. the study fig. 4. respondents level of affordability. source: authors’ survey (2016) table 2. existing space sizes compared to minimum areas required by building laws. source: authors’ survey (2016) housing units no. living room existing (m2) required min. area (m2) bedroom existing (m2) required min. area (m2) kitchen existing (m2) required min. area (m2) location of bath & wc location of kitchen 1 9.0 15.0 9.0 13.6 3.4 6.0 within within 2 9.4 15.0 9.0 13.6 5.4 6.0 within within 3 13.0 15.0 10.8 13.6 5.8 6.0 outside outside 4 10.8 15.0 9.0 13.6 4.0 6.0 within within 5 8.1 15.0 8.1 13.6 5.0 6.0 outside outside 6 15.0 15.0 10.8 13.6 5.0 6.0 within within 7 8.0 15.0 7.2 13.6 3.8 6.0 nil outside 8 8.6 15.0 7.2 13.6 nil 6.0 nil nil 71,40% 13,70% 14,90% 0,00% 10,00% 20,00% 30,00% 40,00% 50,00% 60,00% 70,00% 80,00% unaffordable very unaffordable affordable 21 journal of sustainable architecture and civil engineering 2017/3/20 table 2 existing space sizes compared to minimum areas required by building laws. source: authors’ survey (2016) housing units no. living room existing (m2) required min. area (m2) bedroom existing (m2) required min. area (m2) kitchen existing (m2) required min. area (m2) location of bath & wc location of kitchen 1 9.0 15.0 9.0 13.6 3.4 6.0 within within 2 9.4 15.0 9.0 13.6 5.4 6.0 within within 3 13.0 15.0 10.8 13.6 5.8 6.0 outside outside 4 10.8 15.0 9.0 13.6 4.0 6.0 within within 5 8.1 15.0 8.1 13.6 5.0 6.0 outside outside 6 15.0 15.0 10.8 13.6 5.0 6.0 within within 7 8.0 15.0 7.2 13.6 3.8 6.0 nil outside 8 8.6 15.0 7.2 13.6 nil 6.0 nil nil 9 9.0 15.0 9.0 13.6 3.4 6.0 outside outside 10 13.0 15.0 9.0 13.6 4.5 6.0 within outside 11 9.0 15.0 7.2 13.6 5.8 6.0 outside outside 12 9.0 15.0 7.5 13.6 4.8 6.0 outside outside 13 9.4 15.0 9.0 13.6 nil 6.0 nil nil 14 9.0 15.0 9.0 13.6 nil 6.0 nil nil 15 16 17 18 19 20 10.8 8.6 9.0 9.0 9.0 10 15.0 15.0 15.0 15.0 15.0 15.0 8.6 8.6 9.0 7.2 7.2 9.0 13.6 13.6 13.6 13.6 13.6 13.6 5.5 nil 4.4 nil nil nil 6.0 6.0 6.0 6.0 6.0 6.0 outside outside outside outside outside within outside outside outside nil nil within equally evaluated the level of privacy of individuals in their dwelling units and the results showed that larger proportion of 64.6% describes it as poor. table 2 shows the data derived from the in-depth study of some housing units in the study area, which shows the floor areas of functional spaces in respondents housing units measured against the basic minimum area specified by the existing design standards. the proposed space standards are based on the average sizes of the surveyed housing units, which is practicable taking into consideration the health and comfort of the occupants as well. for example, the size of bedroom space in area according to the minimum standards is 13.6m2. the study shows that almost all the housing units studied had area of bedroom less than the basic minimum required; but with an average size of 8.6 m2. however, the study is proposing an area of 9.0 m2 as the basic minimum area required for bedroom for practicability, health and comfort of the occupants. also, the study showed that none of the houses studied had dining room/space. this suggests that the low-income urban dwellers do not necessarily require dining spaces in their housing units or simply do not place importance on that part of the housing unit. therefore, in this proposal, dining spaces shall be optional for any low-income housing development. however, where it is provided, the minimum space required shall be 5.0m2 as against 7.5 m2 required by the building regulations. journal of sustainable architecture and civil engineering 2017/3/20 22 from the table above, the study has shown that the compliance level of the low-income housing in bayelsa urban centres with the existing minimum housing design is low. this is due to the un-affordability of the standards by the low-income as well as the alien nature of the standards. consequently, the study evaluated various architectural components of the existing minimum standards and regulation vis-a-vis the realities of the low-income housing in the study area. the most important aspects of the standards and regulations considered in this study are sizes of habitable and functional spaces, lighting and ventilation, location of facilities, furnishing, housing design type and approval processes. these are what the researchers opine is crucial and meaningful to the low-income housing design and construction. the use of in-depth interviews from the respondents, key informants, and observation as qualitative data tool as well as measurements, sketches and photographs (data presentation instruments) used during the field work helped to form the basis for the formulation of the proposed minimum housing design standard that will be suitable for the low-income urban dwellers in bayelsa state in their quest to build their houses. the proposed minimum housing design standards recognize that socio-economic realities categorizes people into different income level, thus in urban residential layout and zoning there are low density areas for the high-income earners, the medium density areas for the middle-income group and the high density areas for the low-income earners. therefore, the proposed standards recognize the place of indigenous housing type where all functional and service areas are not all located within the building enclosure like the conventional “foreign” housing type. secondly, the building plans shall incorporate the principle of incremental housing designs stipulating the number of phases required. also, the approval process of these building plans shall be in phases too to reduce cost and encourage the poor to build. thirdly, only architectural drawings shall be required for the approval of low-income residential housing units. based on the above, the following constitute the minimum housing standard for residential housing scheme in bayelsa state nigeria: the proposed minimum housing design standards a every dwelling unit shall have a living room of not less than 12.0 m2 floor area; b dining spaces /areas shall be optional in low-income dwelling units. where provided, it shall have not less than 4.0 m2; c every dwelling unit shall have at least one room, which shall have not less than 9.0 m2 of floor area; d all habitable rooms or spaces within a dwelling unit shall be provided with natural ventilation by means of at least one openable exterior opening (window) with an area of not less than 0.9 x 1.0 m. such openings are directly onto a street or public alley or a yard or court located on the same plot as the building; e all habitable rooms within a dwelling unit shall be equipped with natural light by means of exterior glazed openings with an area not less than 0.9 x 1.0 m; f every dwelling unit shall be provided with a toilet and bathroom within the dwelling unit with an area of 1.2 m2 for toilets equipped with squatter wc that requires small quantity of water for flushing and 1.8 m2 for bathroom equipped only with shower/tub within a housing unit for a single family; g all bathrooms, toilets and similar rooms shall be provided with natural ventilation by means of open-able exterior openings with an area not less than a minimum of 0.36 m2; h the dwelling unit shall have a source of water prevalent in such areas; i every dwelling unit shall be provided with kitchen within or outside the unit, with an area not less than a minimum of 4.0m2. the kitchen may not have a working sink, and hot / cold running water. l width of habitable rooms other than kitch-en shall be not less than 2.40 m; m the dwelling unit shall have a store of suitable size for the family. 23 journal of sustainable architecture and civil engineering 2017/3/20 the above analysis has shown that the minimum housing standards in use at the moment are far beyond what the low-income urban dwellers can comprehend and comply with as most of their housing designs in terms of space requirements, functional space provisions are inadequate and basic services required in any housing unit are lacking, hence it is not practicable. thus, the dire need to propose and re-develop practical minimum housing design standards becomes very important in order to encourage the low-income urban dwellers to build their houses, which will further reduce homelessness among the low-income urban dwellers and prevent the further growth of urban sprawl. it is the belief of the researchers that these proposed standards if implemented by the relevant government agencies would help curb the growing urban sprawl and reduce to the barest minimum the housing deficit and homelessness in nigerian cities. according to the findings in this study, low-income urban dwellers in bayelsa state are living in housing units considered sub-standard judging from the minimum housing standards and building regulation currently being used in the state, consequently, they do not comply with the existing minimum standards. the reason for this non-compliance is the affordability problem and non-suitability of the standards to the socio-economic and life style of the low-income earners who view these standards as foreign. as a result of the unrealistic nature of the existing minimum building regulations and standards in bayelsa state, this study is emphasizing a paradigm shift to the adoption of new enabling regulation that include relaxation of development control codes and practicable minimum housing standards. the enabling concept has as its by-product the idea of self-help housing, preference for local building materials and labour for housing sustainability, housing type suitable for the low-income as well as with “relaxed” and flexible planning and building regulation / housing design standards, which this study has proposed. the bayelsa state government should as a matter of urgency embark on the review or revision of the building standards and regulations used in the state and produce standards and regulation of their own taking into account the peculiarity of the state. this should be holistic and must include standards for floor space, densities, dwelling sizes, plot sizes, flexible / suitable designs for all classes of income earners, building types, building materials specification and incremental policies (designs, construction, approvals and payments). above all, the building regulations and standards when revised should be implemented, enforced and should be flexible. discussion and conclusions references awofeso, p. one out of two nigerians now lives in a city: there are many problems but one solution. world policy journal, 2010; 27: 67. https://doi. org/10.1162/wopj.2011.27.4.67 bayelsa state ministry of information, culture and tourism (bmict). history of bayelsa state: people, culture and economy. yenagoa: bmict press; 2002. bourennane, m. a legal framework for enabling low-income housing. a study of women’s access to home based enterprises in botswana. unpublished doctoral thesis. royal institute of technology, school of architecture and built environment, department of urban planning and environment. stockholm: universities service usa; 2007. bramley, g., bartlett, w., lambert, c. planning the market and private house building. london: ucl press; 1995. burgess, r. the compact city debate: a global perspective. in: compact cities: sustainable urban forms for developing countries. routledge; 2000. federal government of nigeria (fgn). national building code. federal ministry of housing and urban development, abuja; 2006. federal government of nigeria (fgn). national housing policy for nigeria. federal ministry of housing and urban development, abuja; 2012. fin-mark trust. overview of the housing finance sector in nigeria. centre for affordable housing finance in africa. working paper 12: uk dfid. bill and melinda gates foundation, 2010; 1-52. journal of sustainable architecture and civil engineering 2017/3/20 24 hamdi, n. housing without houses – participation, flexibility, enablement. new york: van nostrand reinhold; 1991. gilson, a. j. land availability and housing affordability: the need for a new approach. a paper presented at the institute for housing of southern africa conference: housing affordability in the 1990s. durban; 1990. harber, r. a. hopes in hell. the architectural review: south africa special issue, 1995; 19 (77). jinadu, a. m. understanding the basics of housing. jos: jos university press ltd; 2007. mabogunje, a. i., hardoy, j. e., misra, r. p. shelter provisions in developing countries: the influence of standards and criteria. ney york: john willy and sons; 1978. olotuah, a. o., aiyetan, a. o. sustainable low-cost housing provision in nigeria: a bottom-up, participatory approach. in boyd, d. (ed.) proceedings of 22nd annual arcom conference, 4 – 6 september, birmingham, uk. association of researchers in construction management, 2006; 2: 633 – 639. republic of south africa (rsa), white paper on reconstruction and development: government’s strategy for fundamental transformation; 1994. turner, j. f. c. housing by people: towards autonomy in building environments. london: marion boyars; 1976. turner, j. f. c. managing the recovery of local initiative. paper presented at the seminar on low-cost housing in the arab region, sanaa, yemen, october; 1992. united nations centre for housing building and planning. methods for establishing targets and standards. housing and environmental development, 1974; 2(7): 3-14. vestbro, d. u. enabling housing strategies. keynote lecture at the international conference towards low-cost housing, cairo, egypt, 29-31 may; 2007. walker, a. the social context of built form: the case of informal housing production in mexico city. working paper no 114. london: development and planning unit, university college; 2001. eugene ehimatie atamewan lecturer cross river university of technology, department of architecture main research area sustainable housing and building maintenance & management address cross river university of technology, department of architecture, calabar, nigeria e-mail: atamewaneugene@gmail.com remi ebenezer olagunju assoc. professor department of architecture, school of environmental technology main research area sustainable housing and building maintenance & management address federal university of technology, minna, nigeria tel: +2347065003865 e-mail: olagunju@futminna.edu.ng about the authors 59 journal of sustainable architecture and civil engineering 2018/2/23 *corresponding author: donatas.rekus@ktu.lt analysis of the accuracy of different geodesic measurements methods for measuring roads received 2018/09/24 accepted after revision 2018/11/03 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 59-68 doi 10.5755/j01.sace.23.2.21606 analysis of the accuracy of different geodesic measurements methods for measuring roads jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.21134 donatas rekus*, vilma kriaučiūnaitė-neklejonovienė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48-418, lt-51367 kaunas, lithuania introduction roads, railroads and streets are one of the most important infrastructure, so it is very important rightly construct and to make control geodesic pictures of them. in order to qualitatively and effectively carry out the following operations, it is necessary to assess the methods (advantages and disadvantages) used for these works. the work describes the usage of the measurements devices, their specifications, data analysis and comparison with the most efficient device. railway tracks require more thorough maintenance and analysis than regular roads for cars. defects are here noticed and recorded by using special equipment. construction of railway roads and their exploitation requires optimal accuracy and monitoring of surveying. it is related to maximum allowed speed of trains, the environment, transport and human safety. their monitoring needs to be improved by applying geodetic devices for surveying. comparing analogous surveying conducted using em140 machine with that of geodetic equipment, one can see the advantage of geodetic surveying. technical gaps in the surveying process, data storage and procession were evaluated as well. it was discovered that maintenance and monitoring works should be pursued more frequently using high accuracy geodetic equipment. the main aim of this article is to evaluate differences of the technological process and control technology by conducting geodetic investigation in railway objects. keywords: electronic tacheometer, gnss receiver, railway, geodetic surveying. roads, railway roads and streets are one of the most important infrastructure, so it is very important rightly construct and to make control geodesic pictures of them. in order to qualitatively and effectively carry out the following operations, it is necessary to assess the methods (advantages and disadvantages) used for these works. an important moment is observation and evaluation of railway road condition. railway tracks require more accurate maintenance and analysis than regular roads for cars. defects in regular roads can be noticed and recorded by simple inspection without using any special equipment but rather marking it in the survey. as š. prokopimas states (2017), quality requirements for arranging railway infrastructure objects are always included in the primary conditions of the project and they must be observed within limits of allowed deviations and tolerance throughout the whole process of construction and exploitation (works of rubber ballast compaction and accurate railway road tamping to the project position). precise arrangement of railway roads in the project position, journal of sustainable architecture and civil engineering 2018/2/23 60 observing the deadlines of works by maintaining high quality indices, etc. call for contemporary surveying and observation technologies allowing functional and immediate inspection and regulation of railway road condition throughout construction and exploitation period. the research into organization and optimization of railway road inspection and repair was analysed by a. r. andrade (2008), s. jovanovic (2004), c. a. grimes (1995) d. larson (2004), b. aursudkij, g. r. mcdowell, a. c. collop (2009) and other numerous authors. i. gailienė, i. podagėlis (2008) designed very important evaluation where strength characteristics of lithuanian railway lines upper construction were defined. j. lackenby (2006), b. aursudkij (2007), s. f. brown et al. (2004), skrinskas et al. (2010) conducted relevant research. contemporary construction and exploitation of railway infrastructure objects requires maximum accuracy of surveying in order to increase the speed of trains. exploitation of modern railway roads requires high responsibility of works and more careful monitoring. the article deals with construction, regulation and monitoring works of railway roads. research object: investigation and control geodetic works in the railway territory aim and objectives: the aim is to evaluate differences of the technological process and control technology by conducting geodetic investigation in railway objects. 1. analyse and evaluate differences, assumptions and occurring problems of the technological process by conducting railway geometric investigations. 2. define optimal frequency of geodetic road supervision works (to observe geometry) and appropriate methods. table 1 display of railway road stretches selected for the research selection criteria other conditions selected stretch at least 1 km long; all stretches must have undergone management (repair) process;surveyed at least twice surveyed during different periods no repair works during the research not to disturb the analysis data. data systems of coordinates and heights must correspond geometry and vertical profile data have survived to make comparisons primary project and surveying data can be found used equipment trimble sps930, topconhiper sr and trimble gedo ce 2. homogeneous and calibrated. calibrated before conducting geodetic surveying. steady correction of devices is essential, especially in winter and summer when the temperature differences inside and outside are highly noticeable. 5 objects were selected: 1. k – l 1 km i and ii category road; 2. p – k 2.8 km ii category road; 3. p – r– j 1.20 km i category road; 4. pr – p 2.40 km ii category road; 5. v – ž 1.30 km ii category road. methods research (surveying) was conducted in certain stretches of railway infrastructure. only higher categories (i and ii) roads, which need more careful supervision, were analysed in the research. more stringent requirements due to higher maximum speeds allowed are applied for them. only roads between stations were selected because more favourable conditions affect their state and they are characterized by greater lengths. selection criteria and five objects that match the collected data analysis are displayed in table 1. table 1. display of railway road stretches selected for the research selection criteria other conditions selected stretch at least 1 km long; all stretches must have undergone management (repair) process; surveyed at least twice surveyed during different periods no repair works during the research not to disturb the analysis data. data systems of coordinates and heights must correspond geometry and vertical profile data have survived to make comparisons primary project and surveying data can be found used equipment trimble sps930, topconhiper sr and trimble gedo ce 2. homogeneous and calibrated. calibrated before conducting geodetic surveying. steady correction of devices is essential, especially in winter and summer when the temperature differences inside and outside are highly noticeable. 5 objects were selected: 1. k – l 1 km i and ii category road; 2. p – k 2.8 km ii category road; 3. p – r– j 1.20 km i category road; 4. pr – p 2.40 km ii category road; 5. v – ž 1.30 km ii category road. trimble sps930 electronic tachymeter was used in the research for complicated surveying and monitoring of constructions, railways, tunnels, etc. multifunctional gnss receiver topconhiper sr and surveying trolley trimble gedo ce 2 were employed. trimble gedo ce 2 is employed for gauge geometry, size control and railway infrastructure. the trolley can survey roads which have gauges of different width by changing certain sections (1000 mm, 1067 mm, 1435 mm, 1520 mm, 1600 mm, 1668 mm, 1676 mm, etc. according to special commission). the width of the gauge is surveyed. its error gap ranges from –20 mm to +60 mm. the error of the gauge width is ±0.3 mm. the width of the gauge is surveyed by entering the accurate surveyed distance (location), which is the starting point for calculation of subsequent surveying difference regarding the direction of press wheels. the distinction of the platform arrow is ±10° or ±265 mm. the accuracy of the platform is ±0.5 mm (after point surveying). the platform is calculated according to the sensor where one can enter certain meanings or by turning the trolley twice during surveying and thus obtaining the average value, which is the subsequent starting point for evaluating the platform change according to the width of the gauge and inclination angle. moreover, software gedo office, autocad civil 3d, geosecma was used. the surveying equipment employed was sufficiently accurate if used correctly, inspected and regulated steadily. the equipment was checked and calibrated before starting geodetic surveying works following the requirements the document regulating the use of railway, the basis of using 1520 m width gauge, the main surveying processes of constructions, equipment and rolling stock as well as requirements, maintenance standards, and principles of train traffic and signalizing is regulations of the technical use of railways (rtur). in order to pursue works, it is crucial to ask for vigilance warnings for trains concerning surveying by indicating the kilometres (points of works) and the anticipated period of works; during the preparation period temporary geodetic points are arranged and their surveying is conducted using gnss receiver. geodetic surveying (see fig. 1) is conducted in the following way: • coordination of two primary surveying stations using tachymeter and gnss receiver within the distance of 500 metres. • having built tachymeter on st1, the direction towards st is entered and repetitive surveying is conducted. thus the error of the distance is eliminated, which can be received by gnss surveying; • the distance to benchmark 1 (bm1) is surveyed and railway surveying is conducted – 250 metres to both sides from the tachymeter are calculated, thus forming the section of 500 metres for railway surveying. during surveying the direction is checked every 250 metres (in the middle of surveying near the tachymeter and at the end of research (surveying) was conducted in certain stretches of railway infrastructure. only higher categories (i and ii) roads, which need more careful supervision, were analysed in the research. more stringent requirements due to higher maximum speeds allowed are applied for them. only roads between stations were selected because more favourable conditions affect their state and they are characterized by greater lengths. selection criteria and five objects that match the collected data analysis are displayed in table 1. methods 61 journal of sustainable architecture and civil engineering 2018/2/23 trimble sps930 electronic tachymeter was used in the research for complicated surveying and monitoring of constructions, railways, tunnels, etc. multifunctional gnss receiver topconhiper sr and surveying trolley trimble gedo ce 2 were employed. trimble gedo ce 2 is employed for gauge geometry, size control and railway infrastructure. the trolley can survey roads which have gauges of different width by changing certain sections (1000 mm, 1067 mm, 1435 mm, 1520 mm, 1600 mm, 1668 mm, 1676 mm, etc. according to special commission). the width of the gauge is surveyed. its error gap ranges from –20 mm to +60 mm. the error of the gauge width is ±0.3 mm. the width of the gauge is surveyed by entering the accurate surveyed distance (location), which is the starting point for calculation of subsequent surveying difference regarding the direction of press wheels. the distinction of the platform arrow is ±10° or ±265 mm. the accuracy of the platform is ±0.5 mm (after point surveying). the platform is calculated according to the sensor where one can enter certain meanings or by turning the trolley twice during surveying and thus obtaining the average value, which is the subsequent starting point for evaluating the platform change according to the width of the gauge and inclination angle. moreover, software gedo office, autocad civil 3d, geosecma was used. the surveying equipment employed was sufficiently accurate if used correctly, inspected and regulated steadily. the equipment was checked and calibrated before starting geodetic surveying works following the requirements the document regulating the use of railway, the basis of using 1520 m width gauge, the main surveying processes of constructions, equipment and rolling stock as well as requirements, maintenance standards, and principles of train traffic and signalizing is regulations of the technical use of railways (rtur). in order to pursue works, it is crucial to ask for vigilance warnings for trains concerning surveying by indicating the kilometres (points of works) and the anticipated period of works; during the preparation period temporary geodetic points are arranged and their surveying is conducted using gnss receiver. geodetic surveying (see fig. 1) is conducted in the following way: _ coordination of two primary surveying stations using tachymeter and gnss receiver within the distance of 500 metres. _ having built tachymeter on st1, the direction towards st is entered and repetitive surveying is conducted. thus the error of the distance is eliminated, which can be received by gnss surveying; _ the distance to benchmark 1 (bm1) is surveyed and railway surveying is conducted – 250 metres to both sides from the tachymeter are calculated, thus forming the section of 500 metres for railway surveying. during surveying the direction is checked every 250 metres (in the middle of surveying near the tachymeter and at the end of surveying at the control point) by turning the tachymeter to the already surveyed st2 at the distance of 500 metres. if the direction does not correspond, it is restored and surveying is repeated; fig. 1 the scheme of geodetic surveying technology surveying at the control point) by turning the tachymeter to the already surveyed st2 at the distance of 500 metres. if the direction does not correspond, it is restored and surveying is repeated; • tachymeter is then brought to st2. the distance to st1 is surveyed and the direction and distances to benchmark2 (bm2) and st3 are surveyed as well. the difference of surveying values (x, y, z) is checked in surveying correspondence points; • surveying is proceeded up to the final point in such a way. fig. 1. the scheme of geodetic surveying technology bench marks are arranged every kilometre. two steady tachymeter stops st1 and st2 are equipped between them. in extreme cases, when it is very hot, shorter distances are retained between bench marks. the weather being hot, the number of surveying stops increases. bench marks closest to tachymeter stops are surveyed. the distance not exceeding 500 metres between bench marks is retained. all data surveyed by tachymeters is transformed by changing the location and the altitude of tachymeter stops as well as by aligning hanging geodetic traverse. designing of road reconstruction is pursued using geosecma software. previously designed horizontal and vertical profiles were used in the research by entering their data and comparing it to the data of recent surveying. results in order to ensure railway traffic security, as well as environmental protection and reduction of risk factors for employees, strict rules and requirements are inevitable. one of important and little analysed stages of railway maintenance is identifying the state of the road according to the level, gauges and location in the plan. it must be systematically checked by transfer carriage by decoding recordings in the tape and evaluating deviations on the basis of road evaluation standards. em140 stores data in the closed data base, which is evaluated by responsible individuals (savaeigio kelio…, 2012) of railway infrastructure. having found defected spots of the road geometry, the order to conduct geodetic surveying is issued. on the basis of geodetic surveying findings, repair works are projected and conducted by road track tamping machines (09-32 csm, 09-16 csm, unimat 08-475 4s), i.e. the road is repaired with regard to possibilities. geodetic surveying enables one to receive similar final data to that of road surveying machines em140, 09-32 csm, 09-16 csm, unimat 08-475 4s. however, methods of surveying data analysis and evaluation of findings significantly differ. surveying machines conduct surveying (geležinkelio...,2000) with regard to peculiarities of equipment and its possibilities, i.e. they identify differences when the distance is at least 18 metres. meanwhile findings of geodetic surveying reveal differences even more frequently than every 18 meters and also reflect the changes from the starting point and/or geometry arrangement in the space during the analysed period. data analysis obtained from surveying machines causes problems when evaluating road planning data and more abrupt width of inclination. analysis of geodetic surveying does not have limitations of track evaluation. geodetic equipment allows getting point surveying (when the road is surveyed every 5 meters). are used the data of all. they are evaluated as the whole unity (straight lines, traverse and curve segments). overall total deviation of the road is defined more precisely. surveying machines cannot evaluate this fact. thus, road surveying machine em140, which declares high accuracy, can evaluate only the possibility of train passing in practice but it in any way does not identify total subsidence of the road or road deviations. the aim of the research was to identify road deviation from the project data and compare geometry differences during different periods of time. all surveying was conducted before undertaking repair works. after surveying roads were restored to the project position. systematized data provides maximum deviations of every stretch during the surveying period (table 2). journal of sustainable architecture and civil engineering 2018/2/23 62 _ tachymeter is then brought to st2. the distance to st1 is surveyed and the direction and distances to benchmark2 (bm2) and st3 are surveyed as well. the difference of surveying values (x, y, z) is checked in surveying correspondence points; _ surveying is proceeded up to the final point in such a way. bench marks are arranged every kilometre. two steady tachymeter stops st1 and st2 are equipped between them. in extreme cases, when it is very hot, shorter distances are retained between bench marks. the weather being hot, the number of surveying stops increases. bench marks closest to tachymeter stops are surveyed. the distance not exceeding 500 metres between bench marks is retained. all data surveyed by tachymeters is transformed by changing the location and the altitude of tachymeter stops as well as by aligning hanging geodetic traverse. designing of road reconstruction is pursued using geosecma software. previously designed horizontal and vertical profiles were used in the research by entering their data and comparing it to the data of recent surveying. results in order to ensure railway traffic security, as well as environmental protection and reduction of risk factors for employees, strict rules and requirements are inevitable. one of important and little analysed stages of railway maintenance is identifying the state of the road according to the level, gauges and location in the plan. it must be systematically checked by transfer carriage by decoding recordings in the tape and evaluating deviations on the basis of road evaluation standards. em140 stores data in the closed data base, which is evaluated by responsible individuals (savaeigio kelio…, 2012) of railway infrastructure. having found defected spots of the road geometry, the order to conduct geodetic surveying is issued. on the basis of geodetic surveying findings, repair works are projected and conducted by road track tamping machines (09-32 csm, 09-16 csm, unimat 08-475 4s), i.e. the road is repaired with regard to possibilities. geodetic surveying enables one to receive similar final data to that of road surveying machines em140, 09-32 csm, 09-16 csm, unimat 08-475 4s. however, methods of surveying data analysis and evaluation of findings significantly differ. surveying machines conduct surveying (geležinkelio...,2000) with regard to peculiarities of equipment and its possibilities, i.e. they identify differences when the distance is at least 18 metres. meanwhile findings of geodetic surveying reveal differences even more frequently than every 18 meters and also reflect the changes from the starting point and/or geometry arrangement in the space during the analysed period. data analysis obtained from surveying machines causes problems when evaluating road planning data and more abrupt width of inclination. analysis of geodetic surveying does not have limitations of track evaluation. geodetic equipment allows getting point surveying (when the road is surveyed every 5 meters). are used the data of all. they are evaluated as the whole unity (straight lines, traverse and curve segments). overall total deviation of the road is defined more precisely. surveying machines cannot evaluate this fact. thus, road surveying machine em140, which declares high accuracy, can evaluate only the possibility of train passing in practice but it in any way does not identify total subsidence of the road or road deviations. the aim of the research was to identify road deviation from the project data and compare geometry differences during different periods of time. all surveying was conducted before undertaking repair works. after surveying roads were restored to the project position. systematized data provides maximum deviations of every stretch during the surveying period (table 2). horizontal deviation shows how much road axis has deviated from the project road axis (for instance, the deviation is -167 mm; it means that the road needs to be moved to the right by 167 mm, i.e. 83.5 mm, because at that time in the surveying place it has been distanced to the left). vertical deviation shows how much the road needs to be lifted (for example, +51 the gauge reveals the discrepancy in mm of the distance between two railheads (it is supposed to be 1520 mm). the platform shows how much one rail is higher than the other. 63 journal of sustainable architecture and civil engineering 2018/2/23 by evaluating identified deviations, the criteria is taken into consideration (road gauges for geometry), set for surveying machine em-140 (see table 3). according to these criteria, degree of deviations and maximum deviation limit of crucial speed reduction is defined. if the size of errors has reached iv degree of deviations, the speed of transport is supposed to be reduced down to a lower category. if deviations have reached iv degree and the road speed is reduced to 15 km/h, the road is closed. currently the main way to conduct road geometry analysis is surveying by road machine. the machine defines the necessity to repair the rail road accurately enough in order to ensure appropriate railway traffic. nevertheless, the obtained results do not provide the opportunity to evaluate the total change of railway condition or notice homogeneous subsidence of the road. the instruction of road geometric parameters evaluation k/259 (savaeigio..., 2016) provides the limits that can be used analysing differences of short road segments (see table 3) but it is not suitable for evaluation of long segment deviations. according to the findings of conducted surveying (see table 2), 3 stretches which have i degree deviation and 2 stretches having iii degree deviation (tables 2-3) have been identified. the obtained data shows that the limits for width of gauges have not been exceeded. such a tendency cannot be noticed even regarding differences of time periods. one can claim that 2 stretches have approached a must-repair stage in certain places or maximum projected speed must be reduced. however, they still meet compulsory criteria in order to maintain the necessary maximum speed and can be further exploited as roads of categories i and ii. in general, road deviations depend on precision of the construction, which is ensured during the production process, rather than on the season or the period between road repair works. evaluating the planning road situation, 18 m length road segments are evaluated with help of surveying machines. such analysis ensures train passage and correspondence of the road speed to the criteria. however, it cannot identify real road state correspondence to the original project. road surveying machines are oriented towards analysis of the road state with regard to the perspective of a moving vehicle (because it analyses the state of the road when it is being used). according to the data analysis, it is seen that sudden cases of road gauge damage in railway have been rare and mostly happen in the summer period. in such a way the road is closed and immediate repair works are pursued. in the research all evaluated stretches did not exceed the established geometry requirements for assurance of certain speed, taking into consideration the possibility for trains to run. table 2 maximum deviations in all stretches stretch surveying data deviation from the original project, mm horizontal deviation (– to the left; + to the right) from the project vertical deviation (+ is missing from the project) width of gauges platforms k–l 1 km i and ii class road; 2016-08-23 2016-11-14 i class ii class –1/+1 –2/+2 –7/–1 –7/–2 i class ii class +51 +38 +34 +38 i class ii class –4/+0 –1/+2 –3/+2 –0/+4 i class ii class –4/+8 –21/+0 –5/+6 –23/+0 p–k 3 km ii class road; 2014-09-04 2017-07-19 –167/+73 –203/+81 +113 +113 –4/+9 –4/+8 –8/+10 –5/+6 p–r–j 1.20 km i class road; 2014-04-03 2017-10-02 –182/+161 –183/+161 +144 +104 –6/+2 –7/+4 –5/+4 –8/+8 pr–p 2.40 km ii class road; 2014-09-17 2017-10-26 –190/+155 –95/+182 +91 +41 –5/+5 –2/+4 –5/+9 –0/+8 v–ž 2.40 km ii class road; 2015-11-25 2017-05-25 –170/+42 –150/+73 +156 +110 –9/-2 –7/+5 –9/+2 –8/+11 journal of sustainable architecture and civil engineering 2018/2/23 64 general deviations of road geometry were observed rather than single road deformations. geometry changes have significant impact when curves are being evaluated. however, none of them did not decrease up to the point when the speed of the train must be reduced. on the other hand, if comparing the restored road geometry with initial project data, discrepancies can be noticed. in this case the limit of discrepancies was highly exceeded. as a result, the problem arises when evaluating such situations, namely, actual road characteristics show that the road is suitable for exploitation. however, the road does not meet the initial geometry and is suitable for use only due to additional reserved distances. when evaluating maximum discrepancies to the project, one can see the values exceeding the momentum of 150 mm, which, regarding exploitation characteristics of the train, in practice limits the possibility to manage with one tamping (road repair). in order to conduct correction of the horizontal profile adequately, it is best to use momenta not exceeding 100 mm. the majority of roads exceed practical characteristics of one tamping. the only road that has retained its characteristics was tamped every 2 months while all other roads after 1.5 years of exploitation required repair works again. having exceeded 1.5 years’ period, roads typically require repair and, thus, one can claim that it is crucial to organize surveying more often than the period mentioned (see table 2). evaluating the change of longitudinal profile, frequent pits were found. the analysis helped to notice that railway road construction tends to subside in points of inclination intersections. regarding time, profile and designing tendencies, it has been found that even under similar exploitation conditions certain places have tendencies for pits to form. this situation is best evaluated by conducting geodetic surveying. after surveying, the data is used to find a solution to the problem. it allows defining accurate height and frequency of railway tamping. geodetic surveying in this case not only defines the size of the pit more precisely but also ensures complete restoration. surveying and repair machines can record only larger pits because they have no possibilities to survey them using the laser or the string. when defects are evaluated according to the table by the road machine, the surveying distance is 5.4 metres. analysing at such a distance iii and iv degree road deviations were identified. it means that the speed must be reduced for roads of category iv whereas repair works have to be planned for category iii roads. 2.5 months after the last correction of the road the need for repair was identified. analysing other stretches, it was discovered that after 3 years damaged stretches containing the same aforementioned defects emerged. although the road is still suitable for exploitation, the speed in its segments has to be reduced. thus, additional risk forms because the road loses qualities of speed and stability. table 3 limits of railway road gauge width and location in the plan, limits of pits and deviations. (savaeigio... , 2016) d eg re e of d ev ia tio n limits of rail road width of gauges location in the plan pits deviations road category and defined speed under deviations, mm i ii i ii i ii i ii 140/90 120/80 140/90 120/80 140/90 120/80 140/90 120/80 + + + + + + + + i 8 4 8 4 5 5 5 5 8 4 8 4 5 5 5 5 ii 14 6 14 6 7 7 12 12 14 6 14 6 7 7 12 12 iii 16 8 16 8 12 12 17 17 16 8 16 8 12 12 17 17 iv >16 <8 >16 <8 >12 <12 >17 <17 >16 <8 >16 <8 >12 <12 >17 <17 65 journal of sustainable architecture and civil engineering 2018/2/23 table 4 problematic areas of vertical profile stretch date of the measurements issues of vertical profile inadequacies in the project i category ii category kaišiadorys – livintai 1 km i ir ii road; 2016-08-23 51mm 70m 35mm 300m 28mm 40m 35mm 100m 38mm 40m 27mm 60m 2016-11-14 35mm 200m 22mm 20m 32mm 100m 38mm 40m 25mm 40m palemonas – kaunas 2,8 km ii road; 2014-09-04 60mm 80m 32mm 70m 70mm 640m 47mm 200m 65mm 100m 76mm 200m 113mm 480m 73mm 240m stretch date of the measurements issues of vertical profile inadequacies in the project i category ii category 2017-07-19 67mm 220m 60mm 500m 64mm 120m 33mm 110m 59mm 90m 73mm 160m 113mm 490m 70mm 220m palemonas rokai – jiesia 1,20km i road; 2014-04-03 59mm 200m 82mm 140m 44mm 120m 59mm 140m 26mm 30m 144mm 200m 2017-10-02 29mm 40m 63mm 370m 68mm 230m 104mm 220m pravieniškės – palemonas 2,40km ii road; 2014-09-17 30mm 20m 40mm 140m 29mm 80m 37mm 10m 91mm 1350m 2017-10-26 30mm 120m 41mm 260m 37mm 120m vievis žasliai 1,30km ii road; 2015-11-25 64mm 240m 122mm 460m 93mm 210m 156mm 200m 2017-05-25 35mm 140m 110mm 1100m journal of sustainable architecture and civil engineering 2018/2/23 66 when evaluating the state of the road on the basis of platform discrepancy with the project, the average 8 mm platform discrepancy was identified while following the standards in straight stretches it is supposed not to exceed 6 mm. taking into consideration the general situation, the highest deviations occur at intervals and have no common dependence for the whole stretch but rather emerge in single spots. regarding the periods of time, all the stretches that were analysed were close or even slightly exceeded level iv of the deviation (see table 4). one can claim that is reasonable to observe the road state more frequently than 1.5 years despite the fact that road exploitation is still possible. there were cases when monitoring showed that even after 3 years of exploitation no repair works were necessary. k – l road segment is exceptional where ii category road even after repair works regained the platform of emergency condition within the period of 2 months. therefore, repeated surveying and monitoring were indispensable. nevertheless, such cases are rare and they depend on the state of slopes or ground compaction. having reviewed the obtained data, it was found that analysis of railway road construction was not sufficient. the shortage of archive data of the previously conducted surveying was found. it could be used for monitoring and maintenance. road surveying equipment in the train can roughly identify the state of the road and ensure road safety. however, it cannot evaluate the state of the whole road. steady and renewed regulations are essential for road state observation and repair. it is suggested to pursue railway surveying straight after road repair and 2-3 months after so that steadiness of road state could be evaluated. regular schedule of geodetic surveying supervision should be designed whereas if needed, surveying could be more frequent. road surveying should be conducted once per year on average. the most significant problems are observed after 2 months. currently the road is supervised by identifying the defects by surveying machine. afterwards geodetic surveying is conducted on the basis of data analysis. such a solution allows ensuring minimum compulsory maintenance but it does not provide the possibility to create more favourable conditions for repair and analysis. thus, there is a problem to design road repair schedule and work usually is organized urgently rather than planning in advance. not only is the state of the stretch different but also each stretch kilometre wears differently. in each situation one has to make individual decisions. fig. 2 the proposed railway control measurement technology model design road repair schedule and work usually is organized urgently rather than planning in advance. not only is the state of the stretch different but also each stretch kilometre wears differently. in each situation one has to make individual decisions. fig. 2. the proposed railway control measurement technology model all things considered, one can claim that the state of roads tends to deteriorate although it does not depend on time. it is more affected by the initial project, road exploitation and quality of repair works. in order to ensure fully-fledged supervision of the road state, it is important to conduct surveying more frequently by using geodetic equipment. in such a way not only the possibility of train passing could be evaluated but also initial road characteristics could be preserved and their original place could be restored. having conducted and evaluated research findings, there is a suggestion to pursue surveying straight after repair works. the proximate surveying should be organized no later than 2-3 years after to check the tendencies of road state change (road deviations from the initial state). subsequent actions could be surveying at least once per year. if the state of the road is steady during the first months, surveying could be conducted once per year. if higher deviations are observed, more frequent surveying would allow detect causes of damage and repair the road until defects do not significantly affect road exploitation. conclusions 1. the width of the gauge is the least changing factor, which is characterized by rare, more individual and short sections (̶ 7/+9). replacement of the road platform has more significant impact, which is harder to detect without special equipment though it is of crucial importance in order to ensure safety for trains moving at high speeds, especially in curves. in rare cases higher replacement of the platform occurs related to railway bed or the state of the pad (̶ 8/+11). scheduled tracks and repair of vertical profile require steady supervision as it changes most often and needs correction of 100-200 mm horizontal profile, 100 mm vertical profile, which exceeds the limits of regular one-time correction. 2. the main problems faced are as follows: shortage of regulations defining precise requirements applied for the width of 1520 mm gauges in roads and regulating the procedure of geodetic surveying and parameters, which are used to evaluate the road and actions; geodetic surveying conducted at the wrong time and the tendency to solve problems when the limits of deviations and errors have been exceeded; the lack of specialists in narrow specialization; the lack of favourable conditions for data collection and storage. 3. it is suggested to conduct more frequent surveying of the road straight after repair works. in order to test the tendencies of road state change the subsequent surveying should be planned and conducted no later than in 2-3 months. regular schedule of geodetic surveying supervision should be designed. if necessary, surveying could be organized more frequently. otherwise surveying is supposed to be conducted on average once per year. 67 journal of sustainable architecture and civil engineering 2018/2/23 all things considered, one can claim that the state of roads tends to deteriorate although it does not depend on time. it is more affected by the initial project, road exploitation and quality of repair works. in order to ensure fully-fledged supervision of the road state, it is important to conduct surveying more frequently by using geodetic equipment. in such a way not only the possibility of train passing could be evaluated but also initial road characteristics could be preserved and their original place could be restored. having conducted and evaluated research findings, there is a suggestion to pursue surveying straight after repair works. the proximate surveying should be organized no later than 2-3 years after to check the tendencies of road state change (road deviations from the initial state). subsequent actions could be surveying at least once per year. if the state of the road is steady during the first months, surveying could be conducted once per year. if higher deviations are observed, more frequent surveying would allow detect causes of damage and repair the road until defects do not significantly affect road exploitation. 1 the width of the gauge is the least changing factor, which is characterized by rare, more in-dividual and short sections (– 7/+9). replacement of the road platform has more significant impact, which is harder to detect without special equipment though it is of crucial importance in order to ensure safety for trains moving at high speeds, especially in curves. in rare cases higher replacement of the platform occurs related to railway bed or the state of the pad (– 8/+11). scheduled tracks and repair of vertical profile require steady supervision as it changes most often and needs correction of 100-200 mm horizontal profile, 100 mm vertical profile, which exceeds the limits of regular one-time correction. 2 the main problems faced are as follows: shortage of regulations defining precise require-ments applied for the width of 1520 mm gauges in roads and regulating the procedure of geodetic surveying and parameters, which are used to evaluate the road and actions; geodetic surveying conducted at the wrong time and the tendency to solve problems when the limits of deviations and errors have been exceeded; the lack of specialists in narrow specialization; the lack of favourable conditions for data collection and storage. 3 it is suggested to conduct more frequent surveying of the road straight after repair works. in order to test the tendencies of road state change the subsequent surveying should be planned and conducted no later than in 2-3 months. regular schedule of geodetic surveying supervision should be designed. if necessary, surveying could be organized more frequently. otherwise surveying is supposed to be conducted on average once per year. conclusions andrade a. r. renewal decisions from a life cycle cost (lcc) perspective in railway infrastructure: an in tegrative approach using separate lcc models for rail and ballast components. thesis in civil engineering, technical university of lisbon. lisbon, 2008 . aursudkij b. a laboratory study of railway ballast behaviour under traffic loading and tamping maintenance. phd thesis. university of nottingham, 2007. aursudkij b., mcdowell g. r., collop a. c. cyclic loading of railway ballast under triaxial conditions and in a railway test facility. granular matter, 2009, no 11. p. 391–401. https://doi.org/10.1007/s10035009-0144-4 brown s. f., brodrick b. v., thom n. h., mcdowell g. r. the nottingham railway test facility, 2007. proceedings of the institution of civil engineers – transport volume 160, issue 2, p.59–65. https://doi. org/10.1680/tran.2007.160.2.59 gailienė i., podagėlis i. evaluation of the track superstructure of lithuanian railway lines calculating characteristics of strength. the 7th international conference “environmental engineering”. selected papers. vol. 3. ed. by d. čygas, k. d. froehner, may 22–23, 2008, vilnius, lithuania. vilnius: technika, 2008; p. 1146–1153. geležinkelio kelio priežiūros taisyklės [rules of the railways maintenance]. k/111, 2000. vilnius: leidybos centras (in lithuanian). grimes c. a. application of genetic techniques to the planning of railway track maintenance work. conference on genetic algorithms in engineering references https://doi.org/10.1007/s10035-009-0144-4 https://doi.org/10.1007/s10035-009-0144-4 journal of sustainable architecture and civil engineering 2018/2/23 68 systems: innovations and applications. galesia. iee: sheffield, uk, 414, 1995; p. 467–472. https:// doi.org/10.1049/cp:19951093 jovanovic s. (2004) railway track quality assessment and related decision making. the 2004 ieee international conference on systems, man and cybernetics. the hague, the netherlands vol. 6. 2004; p. 5038–5043. https://doi.org/10.1109/ icsmc.2004.1400992 lackenby j. (2006) triaxial behavior of ballast and the role of confining pressure under cyclic loading. phd thesis. university of wollongong. prokopimas š. (2017) šiuolaikiniai geležinkelių matavimo metodai pasitelkus “trimble gedo”. available at http://www.darnistatyba.lt/gelezinkeliu-matavimo-metodai-trimble-gedo-vorsys-iranga/ (in lithuanian). savaeigio kelio matavimo vagono em1-140 matuojamų geležinkelio kelio geometrinių parametrų įvertinimo instrukcija [instructions for assessing track geometric parameters measured on the self-propelled road wagon em1-140] k/259, 2016. patvirtinta ab “lietuvos geležinkeliai” generalinio direktoriaus 2012 m. sausio 4 d. įsakymu nr. į-10 (in lithuanian). skrinskas s., gasiūnienė v. e., laurinavičius a., podagėlis i. lithuanian mineral resources, their reserves and possibilities for their usage in road building. the baltic journal of road and bridge engineering. no 5 (4), 2010; p. 218–228. donatas rekus doctor of technology science, assoc. prof, kaunas university of technology, faculty of civil engineering and architecture main research area calibration of geodetic instruments, height measurements, geodetic scanning technologies address studentu str. 48-418, kaunas lt-51367, lithuania, tel. +370 37 300479, e-mail: donatas.rekus@ktu.lt vilma kriaučiūnaitė-neklejonovienė doctor of technology science, lecturer kaunas university of technology, faculty of civil engineering and architecture main research area geodesy, rural development, land-use management, real estate management address studentu str. 48-414, kaunas lt-51367, lithuania, tel. +370 37 300479, e-mail: vilma.kriauciunaite@ktu.lt about the authors https://doi.org/10.1049/cp:19951093 https://doi.org/10.1049/cp:19951093 https://doi.org/10.1109/icsmc.2004.1400992 https://doi.org/10.1109/icsmc.2004.1400992 mailto:donatas.rekus@ktu.lt 25 journal of sustainable architecture and civil engineering 2018/2/23 *corresponding author: rokas.valancius@ktu.lt solar photovoltaic systems in the built environment: today trends and future challenges received 2018/08/08 accepted after revision 2018/09/27 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 25-38 doi 10.5755/j01.sace.23.2.21268 solar photovoltaic systems in the built environment: today trends and future challenges jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.21268 anju singh national institute of solar energy, department of solar thermal, gurugram, haryana 122003, india anies mutiari center for material and technical product, ministry of industry of republic indonesia, jl. sangkuriang 14, 40135 bandung west java, indonesia cynthia alexander seychelles energy commission, po box 1488, palms street, victoria, mahe, seychelles diana arteta de la cruz pontifical catholic university of peru, av. universitaria 1801, san miguel, lima 32, peru federico e. del pozo jr industrial technology development institute of science and technology, dost compound, bicutan, taguig city, philippines rokas valancius* kaunas university of technology, faculty of civil engineering and architecture, studentų st. 48, lt-51367 kaunas, lithuania over the last decade, the research trends on pv systems are mainly focused on improving reliability, efficiency, and power quality, reducing the cost, integrating at various scales with a grid and contributing to development of microgrid and smart grid solutions. at the same time, many companies in recent years have been focusing on building-integrated pv systems, solar flowers, solar roadways, solar street lights and other innovative solutions for the built environment. this paper presents a review of the past and present status, as well as the future challenges of solar photovoltaic technology in the built environment. the main focus in the paper is put on a current technology, contemporary research trends and future challenges. the various aspects related to the global renewable energy sources and the pv markets, the cost and technology of photovoltaic modules are addressed and discussed. keywords: renewable energy sources (res), photovoltaic (pv) systems; building-integrated pv systems (bipv), pv prices. journal of sustainable architecture and civil engineering 2018/2/23 26 introduction currently the most energy systems are based on burning of fossil fuels that are still dominating worldwide. however, fossil fuels are nonrenewable and emit directly greenhouse gases to the environment. this has been leading to serious environmental and health impacts (malinowski et al. 2017). furthermore, in a lot of countries the fluctuating price of fossil fuels has serious impact on the energy security. there are several alternative resources that can provide clean, continuous, and renewable energies such as: solar, wind, biomass, hydropower, and geothermal. the renewable energy sources (res) are receiving significant attention worldwide as a sustainable alternative type of energy supply being an important sector of the global energy generation (abu-rub et al. 2014). res meets 40% of the increase in primary demand and their explosive growth in the power sector marks the end of boom years for coal. the rapid deployment of solar photovoltaics (pv), led by china and india, helps solar to become the largest source of low-carbon capacity by 2040 (world energy outlook 2017). res is clean and environmental friendly resource; they play an important role in reducing greenhouse gas emissions. investing in res could help in reaching little to no global warming effects and gas emissions, which would help in improving public health and in protecting our environment (ellabban et al. 2014). it improves human life quality by providing enormous and inexhaustible energy supply, with more jobs, and other economic benefits such as stable energy prices. the wide spread of res has even more benefits than above mentioned economic, health, and environmental aspects. in 1958, the us navy finally let few small pv cell–powered radio transmitters go into orbit on the satellite called vanguard i. by 1972, approximately 1000 satellites were running on solar power. this meant that more money was spent on improving pv cells. however, the pv cells were still too expensive for use on earth. in 1971, the price of pv power was 200 times the price of regular electricity in the usa. at the end of 2017 the price for crystalline silicon cells was lower than 0.30 €/w (see the fig. 1), which is 200 times less than 40 years ago. since the first application in space missions, the solar pv technology has come a long way. all over the world, a breakthrough in costs was observed over the last years, following a decade of massive investment in research and deployment. the pv systems today gather the highest global attention because of its numerous advantages: _ easy transportation and light weight; _ easy design and installation; _ quiet energy conversion; _ in most cases nice architectural visibility; _ long lifetime with less maintenance requirement compared to other res technologies. it is obvious, that the prices of pv systems are very important for the vast deployment. in germany prices of a typical 10 to 100 kwp rooftop pv system were around 14,000 €/kwp in 1990. at the end of 2016, such systems cost about 1,270 €/kwp. in 2018 prices of small (up to 10 kwp) domestic rooftop pv system in lithuania have dropped below 1,100 €/kwp (eso 2018, terma 2018). this is a net-price regression of more than 90% over a period less than 30 year. the price drop on pv is expected to continue. from 2009 to 2015, there was 56% reduction in the total cost: 77% in the pv modules, 45% in inverter cost, and 44% in installation-related costs (chung et al. 2015). in recent years prices dropped additionally up to 10% for each year. all this helped in promoting this technology worldwide as a possible alternative to all other energy sources, renewables, and traditional sources. dropping prices of pv systems and a rising demand lured new players into the solar industry, including electric utilities, oil and gas companies. during 2016, at least 98 gwdc of solar pv capacity was added worldwide, it is the equivalent to the installation of more than 40,000 solar panels every hour. more solar pv was installed than the net capacity additions of fossil fuels and nuclear power combined. by the year’s end, global solar pv capacity totaled at least 402 gw, see the fig. 1 (ren21 2018). 27 journal of sustainable architecture and civil engineering 2018/2/23 china, the united states, india, japan and turkey – were responsible for nearly 84% of newly installed pv capacity. the next five were germany, australia, the republic of korea, the united kingdom and brazil. for cumulative capacity, the top countries were china, the united states, japan, germany and italy, with india not far behind. despite the heavy concentration in a handful of countries, new markets are emerging and many countries have begun to contribute significantly to global growth. by the end of 2017, every continent had installed at least 1 gw and at least 29 countries had 1 gw or more of capacity. the leaders for solar pv capacity per inhabitant were germany, japan, belgium, italy and australia (ren21 2018). solar pv capacity in top 10 countries compared to population of country presented in fig. 2. fig. 1 the global capacity of the solar pv systems (ren21 2018) and average price of crystalline silicon pv cells 2007-2017 0.30 €/w (see the figure 1), which is 200 times less than 40 years ago. since the first application in space missions, the solar pv technology has come a long way. all over the world, a breakthrough in costs was observed over the last years, following a decade of massive investment in research and deployment. the pv systems today gather the highest global attention because of its numerous advantages:  easy transportation and light weight;  easy design and installation;  quiet energy conversion;  in most cases nice architectural visibility;  long lifetime with less maintenance requirement compared to other res technologies. it is obvious, that the prices of pv systems are very important for the vast deployment. in germany prices of a typical 10 to 100 kwp rooftop pv system were around 14,000 €/kwp in 1990. at the end of 2016, such systems cost about 1,270 €/kwp. in 2018 prices of small (up to 10 kwp) domestic rooftop pv system in lithuania have dropped below 1,100 €/kwp (eso 2018, terma 2018). this is a net-price regression of more than 90% over a period less than 30 year. the price drop on pv is expected to continue. from 2009 to 2015, there was 56% reduction in the total cost: 77% in the pv modules, 45% in inverter cost, and 44% in installation-related costs (chung et al. 2015). in recent years prices dropped additionally up to 10% for each year. all this helped in promoting this technology worldwide as a possible alternative to all other energy sources, renewables, and traditional sources. dropping prices of pv systems and a rising demand lured new players into the solar industry, including electric utilities, oil and gas companies. during 2016, at least 98 gwdc of solar pv capacity was added worldwide, it is the equivalent to the installation of more than 40,000 solar panels every hour. more solar pv was installed than the net capacity additions of fossil fuels and nuclear power combined. by the year’s end, global solar pv capacity totaled at least 402 gw, see the figure 1 (ren21 2018). fig. 1. the global capacity of the solar pv systems (ren21 2018) and average price of crystalline silicon pv cells 20072017. china, the united states, india, japan and turkey – were responsible for nearly 84% of newly installed pv capacity. the next five were germany, australia, the republic of korea, the united kingdom and brazil. for cumulative capacity, the top countries were china, the united states, japan, germany and italy, with india not far behind. despite the heavy concentration in a handful of countries, new markets are emerging and many countries have begun to contribute significantly to global growth. by the end of 2017, every continent had installed at least 1 gw and at least 29 countries had 1 gw or more of capacity. the leaders for solar pv capacity per inhabitant were germany, japan, belgium, italy and australia (ren21 2018). solar pv capacity in top 10 countries compared to population of country presented in figure 2. the grid-connected solar pv is the most promising technology for solving future energy demands. the researches related to pv are currently concentrated on the improvement and solutions for higher efficiency and lower price of the pv panels and systems, as well as capturing the maximum possible amount of energy from the pv panels (femia et al. 2012). also the researches focus on power electronic converters for standalone and grid connections, development of efficient pv power converter topologies, solutions of challenges of power quality with grid-tie systems, reliable and cost-effective storage, and integration with smart grid systems [adefarati and bansal 2016; zhou et al. 2015; alam et al. 2015]. fig. 2. the capacity of solar pv in the top 10 countries, 2017 (ren21 2018) compared to population of country (wikipedia 2018) in most countries, the grid-connected solar pv system has promising reduction to be competitive with the popular energy sources. the main application of solar energy systems is to act as clean power source connected to the electrical grid (romero-cadaval et al. 2015). however, there are many additional applications of solar energy, that can be very perspective in different countries, such as: solar water pumps, agrophotovoltaics systems, solar feeding of the telecommunication base towers, solar energy in building managements systems, solar energy in microgrids, smart grid, charging infrastructures of electric vehicles; solar energy for marine, satellite, and many other applications. the aim of this paper is to review the past and the present status and future challenges of different solar pv systems focusing on pv systems in the built environment all over the world. 1. the general scheme of pv systems pv cells arranged into panels can be used in largescale pv projects. a rooftop pv system can comprise few or hundreds of panels, while a large-scale project may consist of thousands or even millions of panels. pv systems are generally classified according to their functional and operational requirements, their component configurations, and how the equipment is connected to other power sources and electrical loads. the two principal classifications are on-grid (grid-connected) systems and off-grid (standalone) systems. typical components of a solar pv system (see the figure 3) and their functions:  solar pv modules or solar panels. these panels convert light (i.e. photo) into electrical power (voltage). different technologies and efficiency of pv cells are described below. fig. 2 the capacity of solar pv in the top 10 countries, 2017 (ren21 2018) compared to population of country (wikipedia 2018) journal of sustainable architecture and civil engineering 2018/2/23 28 the grid-connected solar pv is the most promising technology for solving future energy demands. the researches related to pv are currently concentrated on the improvement and solutions for higher efficiency and lower price of the pv panels and systems, as well as capturing the maximum possible amount of energy from the pv panels (femia et al. 2012). also the researches focus on power electronic converters for standalone and grid connections, development of efficient pv power converter topologies, solutions of challenges of power quality with grid-tie systems, reliable and cost-effective storage, and integration with smart grid systems [adefarati and bansal 2016; zhou et al. 2015; alam et al. 2015]. in most countries, the grid-connected solar pv system has promising reduction to be competitive with the popular energy sources. the main application of solar energy systems is to act as clean power source connected to the electrical grid (romero-cadaval et al. 2015). however, there are many additional applications of solar energy, that can be very perspective in different countries, such as: solar water pumps, agrophotovoltaics systems, solar feeding of the telecommunication base towers, solar energy in building managements systems, solar energy in microgrids, smart grid, charging infrastructures of electric vehicles; solar energy for marine, satellite, and many other applications. the aim of this paper is to review the past and the present status and future challenges of different solar pv systems focusing on pv systems in the built environment all over the world. the general scheme of pv systems pv cells arranged into panels can be used in largescale pv projects. a rooftop pv system can comprise few or hundreds of panels, while a large-scale project may consist of thousands or even millions of panels. pv systems are generally classified according to their functional and operational requirements, their component configurations, and how the equipment is connected to other power sources and electrical loads. the two principal classifications are on-grid (grid-connected) systems and off-grid (standalone) systems. typical components of a solar pv system (see the fig. 3) and their functions: _ solar pv modules or solar panels. these panels convert light (i.e. photo) into electrical power (voltage). different technologies and efficiency of pv cells are described below. _ an inverter, the brain of a pv system serves primarily two purposes: to convert the dc power generated from solar panels into ac power that is used by our electrical appliances; to fig. 3 typical components and parts of pv systems.  an inverter, the brain of a pv system serves primarily two purposes: to convert the dc power generated from solar panels into ac power that is used by our electrical appliances; to ensure that solar power generated is used at priority over grid supply. solar inverters are essentially on-grid or off-grid/hybrid. the on-grid inverters are directly connected to the grid supply. the off-grid or hybrid inverters are connected to the specific loads to be run.  a battery. batteries are required to make power available in the absence of sun in off-grid pv systems. batteries are an optional component for on-grid installations.  mounting structures. these are fixtures that hold the solar panel in place (a roof, ground, etc.). their appropriate design is essential to make sure, the panels get maximum sunlight.  electrical and safety equipment. the different parts of pv system are connected by cables on dc and ac side. it is also important to install safety equipment. electrical surges or short circuit can damage the equipment. proper earthing and equipment like residual current circuit breaker, surge protectors, lightening arrestors, etc. are required. these components are same all over the world. however, based on the region of your residence, the type of used components may vary. pv systems have a long life. therefore, it is important to emphasize on quality and safety for durable performance. fig. 3. typical components and parts of pv systems. 1.2 pv cells the pv cell (solar cell) is made from solid-state material that converts the energy of light (photons) into the electric form using the pv effect. there are different types of materials used for the design of pv cells. the crystalline materials used for cells design are single crystalline (sc-si) with a czochralski (cz) float zone (fz) technology; multicrystalline (mc-si) with a cast, sheet, ribbon growth technology; polycrystalline (pc-si) with a chemical-vapor deposition technology; and microcrystalline (mcsi) with a plasma deposition. the main difference between these materials is the regularity level and structure, which affects the size of the crystals making such material. there are other types of solar cells such as thin film, including amorphous silicon (a-si), cadmium telluride (cdte), and copper indium gallium selenide (ci(g)s) (lee and ebong 2015). additional types may also be found such as desensitized solar cells (dsscs), gallium arsenide germanium (gaas) solar cells, luminescent solar concentrator (lsc) cells, multijunction (mj) solar cells, organic solar cells (opv), perovskite solar cells, photoelectron chemical cells (pecs), plasmonic solar cells, plastic solar cells, polymer solar cells, quantum dot solar cells, etc. next to these pv technologies, a wide range of colorful pv cells are now available on market and will open new opportunities for pv systems in the built environment, where not only efficiency or price are most important factors. the output power of pv panels is sensitive to the environmental conditions such as solar irradiation intensity, ambient temperature and dust. the efficiency of commercial pv panels is still relatively low, but in the last decade, the efficiency of average commercial wafer-based silicon modules increased from about 12% to 17% (super-mono 21%). at the same time, 29 journal of sustainable architecture and civil engineering 2018/2/23 ensure that solar power generated is used at priority over grid supply. solar inverters are essentially on-grid or off-grid/hybrid. the on-grid inverters are directly connected to the grid supply. the off-grid or hybrid inverters are connected to the specific loads to be run. _ a battery. batteries are required to make power available in the absence of sun in off-grid pv systems. batteries are an optional component for on-grid installations. _ mounting structures. these are fixtures that hold the solar panel in place (a roof, ground, etc.). their appropriate design is essential to make sure, the panels get maximum sunlight. _ electrical and safety equipment. the different parts of pv system are connected by cables on dc and ac side. it is also important to install safety equipment. electrical surges or short circuit can damage the equipment. proper earthing and equipment like residual current circuit breaker, surge protectors, lightening arrestors, etc. are required. these components are same all over the world. however, based on the region of your residence, the type of used components may vary. pv systems have a long life. therefore, it is important to emphasize on quality and safety for durable performance. pv cells the pv cell (solar cell) is made from solid-state material that converts the energy of light (photons) into the electric form using the pv effect. there are different types of materials used for the design of pv cells. the crystalline materials used for cells design are single crystalline (sc-si) with a czochralski (cz) float zone (fz) technology; multicrystalline (mc-si) with a cast, sheet, ribbon growth technology; polycrystalline (pc-si) with a chemical-vapor deposition technology; and microcrystalline (mc-si) with a plasma deposition. the main difference between these materials is the regularity level and structure, which affects the size of the crystals making such material. there are other types of solar cells such as thin film, including amorphous silicon (a-si), cadmium telluride (cdte), and copper indium gallium selenide (ci(g)s) (lee and ebong 2015). additional types may also be found such as desensitized solar cells (dsscs), gallium arsenide germanium (gaas) solar cells, luminescent solar concentrator (lsc) cells, multijunction (mj) solar cells, organic solar cells (opv), perovskite solar cells, photoelectron chemical cells (pecs), plasmonic solar cells, plastic solar cells, polymer solar cells, quantum dot solar cells, etc. next to these pv technologies, a wide range of colorful pv cells are now available on market and will open new opportunities for pv systems in the built environment, where not only efficiency or price are most important factors. the output power of pv panels is sensitive to the environmental conditions such as solar irradiation intensity, ambient temperature and dust. the efficiency of commercial pv panels is still relatively low, but in the last decade, the efficiency of average commercial wafer-based silicon modules increased from about 12% to 17% (super-mono 21%). at the same time, efficiency of the cdte module increased from 9% to 16%. in the laboratory, best performing modules are based on monocrystalline silicon with 24.4% efficiency. the record efficiencies demonstrate the potential for further increase of efficiency at the production level. the record lab cell efficiency is 26.7% for mono-crystalline and 22.3% for multi-crystalline silicon wafer-based technology. the highest lab efficiency in thin film technology is 21.7% for cigs and 21.0% for cdte solar cells (photovoltaics report 2018). nowadays in a laboratory, high concentration multi-junction solar cells achieve an efficiency to 46.0%. with the concentrator technology, module efficiencies have been increased to 38.9%. still a lot of research and development is required in this direction. the record efficiencies demonstrate the need for further improvement of efficiency at the production level. this is a major challenge for future research to increase potentially the efficiency of pv panels at production scale with a reasonable price. si-wajournal of sustainable architecture and civil engineering 2018/2/23 30 fer based pv technology accounted for about 94% of the total production in 2016. the share of multi-crystalline technology is now about 70% of the total production (photovoltaics report 2018). on-grid pv systems the grid-connected pv systems have been the most popular during the last decade because they are much cheaper compared with the off-grid pv system. on-grid systems don’t require expensive battery systems and other equipment. the grid-connected pv systems can be divided into three different groups: _ high-power pv plants are now installed extensively worldwide and represented 61% of the pv market during 2015. over the last decade, the maximum power of a single pv plant has increased from 50 mw to more than 500 mw in 2017. the biggest pv plant in the world is in benban, egypt with a total capacity of 1.8 gw. the park is set to start working at its full capacity at the beginning of 2019. _ residential and industrial pv applications, when the power of the pv system is lower than 50 kw approximately, the cost of the power converter is still the key but other issues such as efficiency, energy yield, and distributed operation gain importance. _ low-power pv systems, which are usually hundreds of watts (or even in the kilowatt) range and the pv converter design has to be in this case mainly focused on achieving very high efficiency to a single-phase grid. usually, the power converter is directly connected to a single pv module or a small pv array. off-grid pv systems the off-grid pv power systems in recent years has lost their share in total cumulative pv capacity of the global market due to dynamic development of the grid-connected systems. the market share of standalone pv systems over the last 15 years reduced from 15% in 2000 to below 0.5% in 2015 (trends 2016 in photovoltaic applications, 2016). however, this part of pv application has important social aspects because there are still 1.2 billion people all over the world living without access to the electric grid, and pv is the most important power source for them (off-grid solar market trends report 2018). for those people, particularly standalone pv installations have become a viable solution for creating hybrid systems with energy storage and gas/diesel generators as part of bigger islanded microgrids (protogeropoulos et al. 2006; kojima et al. 2007). the issue of transforming to smart grid and solving the problems in rural areas is becoming more attractive for research and deployment. generally, standalone pv applications can be divided into the following: _ pico pv systems (p ≤ 10 wp), lanterns and simple multi-light systems (which may enable mobile charging); _ domestic pv systems (10 wp < p ≤ 10 kwp); _ commercial/institutional pv systems (p > 10 kwp). the pico segment’s estimated growth of overall market in terms of units sold has recently slowed. while slowing growth rates are natural for a sector that, as of 2016, had a base of over 90 million cumulative devices sold (including close to 30 million affiliate devices), the sharp decline was still surprising (off-grid solar market trends report 2018). the other off-grid domestic and commercial pv installations are not similarly impressive. their share was 70 mw in 2015, while the cumulative capacity was 1 gw. this share is very minor in comparison to 195 gw of total cumulative capacity of grid-connected installations. leading countries in standalone systems are china, australia, japan and spain (trends 2016 in photovoltaic applications, 2016). energy storage systems (batteries) can be classified as small local (up to 50 kwh) and distributed (with capacity above 50 kwh). usage of energy storage systems supporting power system 31 journal of sustainable architecture and civil engineering 2018/2/23 in last decade was based respectively on sodium-sulphur, nickel-cadmium, advanced lead-acid, redox-flow, and lithium-ion batteries. in recent years, the situation changed with significantly increased installations based on lithium-ion batteries, when compared to others, but existing capacity is still low. future investment and installation in energy storage is promising. many forecasts show multiple annual power market capacity increase in the next years and price drop of batteries from 350-750 €/kwp in 2017 to 200 €/kwp in 2019 (pv magazine 2017). however, that is not enough for vast development of off-grid or hybrid systems. pv systems in the built environment the modern built environment creates numerous challenges for the deployment of pv technology. in one hand, sometimes it is technically very difficult to install pv systems in an existing built environment, on the other hand the large structures that dominate the skyline of every city create compactness, which, in turn, limits the available rooftop area and creates unpredicted shading patterns. researchers are exploring a number of unconventional solar applications that could promise to transform the pv industry; some of them are described below. building-integrated pv systems while the installation of pv panels on flat and tilted roofs is perhaps the most popular example of its application in buildings, the building-integrated pv systems (bipv), also offer tremendous potential. bipv in new and existing structures offers great possibilities for the design of energy efficient and ecologically sound buildings, without compromising comfort or aesthetics. in addition to design benefits, bipv offers several cost benefits. bipv panels generate electricity and act as part of the building fabric. this combined function can result in costs savings where the cost of traditional building fabric is comparable to that of the pv panels. also, no additional land or separate support structure is required, giving further cost advantages. bipv helps designers to meet goals of sustainability and reduced emissions while maintaining or improving comfort. the synergy between bipv main functions of on-site energy generation and forming part of the building fabric, along with increasing cost competitiveness makes bipv an especially attractive option. the wide range of bipv solutions offered in the market helps develop sustainable buildings: glass solar tiles (solar roof), pure curtain wall, ventilated, cold, warm, climate, second skin and triple skin facades, etc. the wide range of colourful pv cells (green, orange, yellow, light red, dark red, light blue, dark blue, light grey dark grey, purple, white, black, etc.) are now available on the market and will open new opportunities of integrating artistically bipv systems. solar street lights solar streetlight has become a trending because it provides illumination after daylight without addition to the demand on electricity. modern streetlight uses high-intensity discharge lamps and low-pressure sodium (rea et al., 2009). despite their tremendous heat produce and abundance of illumination this type of lighting entails to a huge electricity requirement. when the solar streetlight was introduced, led lighting system has been incorporated. this enabled street light manufacturers to maximize the lifetime of battery since led’s are low consumption lightings. the basic components of solar streetlight are solar panel, lighting fixture, rechargeable battery and its pole. in case of weather disturbances, solar streetlight maybe on its disadvantages since the capacity of solar charging of battery may be not enough to sustain overnight. this dilemma can be answered by using a grid-tied solar streetlighting that is invented in the us by michael hodulik. instead of relying on the charged battery, the grid-tied solar streetlight may be supplied by the distribution line. hybrid system is also an advantage for solar streetlighting (lagorse, 2009). this practical type of solar streetlight uses solar and wind energy as a main supply for streetlighting. for instance, if journal of sustainable architecture and civil engineering 2018/2/23 32 the solar panel didn’t produce enough solar energy, the wind turbine will compensate to sustain the charging of battery. floating pv systems rooftop or ground installations are not the only options for solar modules. developers have now designed systems that can float on channels, lakes or ponds. compared with traditional terrestrial pv systems, floating pv systems can save a lot of land and water resources and obtain higher power generation efficiency. based on the water cooling effect, the efficiency of floating pv systems can increase by about 1.58-2.00 % compared with traditional terrestrial pv systems (luyao et al. 2017). however, in the case of seawater environment like lagoons or oceans, there are concerns on corrosion, humidity and cleaning the salt deposition frequently. the influence of floating pv systems on the ecological environment such as water quality should be carefully examined. in addition, the infrastructure needs to be planned and developed to facilitate the development of floating pv systems. the floating pv power generation technology today is still a new type of power generation technology and there are still a lot of issues worth studying. despite that in recent years around 1 gw of capacity has already been installed around the world. china is a leading country with their construction of floating pv farm with a capacity of 40 mw in an abandoned coal mine of china’s anhui province. till the end of 2017 the world’s only seawater floating pv farm was located at maldives. solar roadways onyx solar has developed the first anti-slip, “walkable” pv paver in the world. pv pavers allow building owners to install solar energy on rooftops, while preserving their habitability (onyx solar, 2018). traditional pv panels take up all the space on the roof, reducing the amenity space within any building. in contrast, the pv pavers let an owner generate free electricity, while still letting people enjoy the space and walk on top of them, safely. the pv pavers can be manufactured using any of the solar technologies (amorphous silicon and crystalline silicon), and they comply with the highest and most stringent quality standards. they are intended for pedestrian traffic only, and they are installed as any technical, raised outdoors flooring system (pvc pedestals, wood and metal framing). they withstand up to 400 kg (point load), can be manufactured in standard dimensions, and customized ones. pv trees solar trees (see the fig. 4) is an environmental enterprise, an ecological sculpture that aims to promote awareness to sustainability within the community. it is an independent unit that produces electricity and provides a place of comfort and energy for a wide variety of services, such as: free wi-fi, docking stations for smart phones and other electric devices, a water cooler with fresh running drinking water, trough for pets, illumination by night (solargiving, 2018). recently a simpler version of pv tree concept (pv public space service) was presented by lithuanian company suneco. a pv public space service stop consists of 250 wp solar panel and 100 ah batteries. an integrated solution provides a wide range of options tailored to needs and purposes. solar flowers the solar flower (smartflower) name comes from its design – the solar cells are arranged on individual “petals” that open at the beginning of each day (see the fig. 4). after the sun goes down, the smartflowers petals fold up and a self-cleaning process kicks in. in addition to solar cells, the smartflower system contains a dual-axis tracker that makes it possible for its “petals” to follow the sun across the sky throughout the day. thanks to this tracking capability, the smartflower can produce significantly more electricity than a similarly-sized rooftop solar panel system – up to 33 journal of sustainable architecture and civil engineering 2018/2/23 51 percent more (starflower solar 2018). the 12-petal, 18 m2 structure comes with 2.5 kilowatts (kw) of electricity production, which is equivalent to a standard 4 kw fixed rooftop array. however, investments for the solar flower are about 50% bigger compared to similar size rooftop solar panel system. smartflower buyers pay a price premium for the folding, self-cleaning, and aesthetic benefits of the smartflower over competing alternatives (smartflower solar: the complete review 2017). fig. 4 pv tree and solar flower (producers photos) onyx solar has developed the first anti-slip, “walkable” pv paver in the world. pv pavers allow building owners to install solar energy on rooftops, while preserving their habitability (onyx solar, 2018). traditional pv panels take up all the space on the roof, reducing the amenity space within any building. in contrast, the pv pavers let an owner generate free electricity, while still letting people enjoy the space and walk on top of them, safely. the pv pavers can be manufactured using any of the solar technologies (amorphous silicon and crystalline silicon), and they comply with the highest and most stringent quality standards. they are intended for pedestrian traffic only, and they are installed as any technical, raised outdoors flooring system (pvc pedestals, wood and metal framing). they withstand up to 400 kg (point load), can be manufactured in standard dimensions, and customized ones. 2.5 pv trees solar trees (see the figure 4) is an environmental enterprise, an ecological sculpture that aims to promote awareness to sustainability within the community. it is an independent unit that produces electricity and provides a place of comfort and energy for a wide variety of services, such as: free wi-fi, docking stations for smart phones and other electric devices, a water cooler with fresh running drinking water, trough for pets, illumination by night (solargiving, 2018). recently a simpler version of pv tree concept (pv public space service) was presented by lithuanian company suneco. a pv public space service stop consists of 250 wp solar panel and 100 ah batteries. an integrated solution provides a wide range of options tailored to needs and purposes. 2.6 solar flowers the solar flower (smartflower) name comes from its design – the solar cells are arranged on individual “petals” that open at the beginning of each day (see the figure 4). after the sun goes down, the smartflowers petals fold up and a selfcleaning process kicks in. in addition to solar cells, the smartflower system contains a dual-axis tracker that makes it possible for its “petals” to follow the sun across the sky throughout the day. thanks to this tracking capability, the smartflower can produce significantly more electricity than a similarly-sized rooftop solar panel system – up to 51 percent more (starflower solar 2018). the 12-petal, 18 m2 structure comes with 2.5 kilowatts (kw) of electricity production, which is equivalent to a standard 4 kw fixed rooftop array. however, investments for the solar flower are about 50% bigger compared to similar size rooftop solar panel system. smartflower buyers pay a price premium for the folding, self-cleaning, and aesthetic benefits of the smartflower over competing alternatives (smartflower solar: the complete review 2017). fig. 4. pv tree and solar flower (producers photos). 3. non-technical possibilities and barriers for res and pv systems in different countries many developments over the last few years have affected the deployment of res, including the lowest prices of pv systems, the decision of several countries to become coal-free, new policies and partnerships, carbon pricing, and new initiatives and goals set by governments at all levels. onyx solar has developed the first anti-slip, “walkable” pv paver in the world. pv pavers allow building owners to install solar energy on rooftops, while preserving their habitability (onyx solar, 2018). traditional pv panels take up all the space on the roof, reducing the amenity space within any building. in contrast, the pv pavers let an owner generate free electricity, while still letting people enjoy the space and walk on top of them, safely. the pv pavers can be manufactured using any of the solar technologies (amorphous silicon and crystalline silicon), and they comply with the highest and most stringent quality standards. they are intended for pedestrian traffic only, and they are installed as any technical, raised outdoors flooring system (pvc pedestals, wood and metal framing). they withstand up to 400 kg (point load), can be manufactured in standard dimensions, and customized ones. 2.5 pv trees solar trees (see the figure 4) is an environmental enterprise, an ecological sculpture that aims to promote awareness to sustainability within the community. it is an independent unit that produces electricity and provides a place of comfort and energy for a wide variety of services, such as: free wi-fi, docking stations for smart phones and other electric devices, a water cooler with fresh running drinking water, trough for pets, illumination by night (solargiving, 2018). recently a simpler version of pv tree concept (pv public space service) was presented by lithuanian company suneco. a pv public space service stop consists of 250 wp solar panel and 100 ah batteries. an integrated solution provides a wide range of options tailored to needs and purposes. 2.6 solar flowers the solar flower (smartflower) name comes from its design – the solar cells are arranged on individual “petals” that open at the beginning of each day (see the figure 4). after the sun goes down, the smartflowers petals fold up and a selfcleaning process kicks in. in addition to solar cells, the smartflower system contains a dual-axis tracker that makes it possible for its “petals” to follow the sun across the sky throughout the day. thanks to this tracking capability, the smartflower can produce significantly more electricity than a similarly-sized rooftop solar panel system – up to 51 percent more (starflower solar 2018). the 12-petal, 18 m2 structure comes with 2.5 kilowatts (kw) of electricity production, which is equivalent to a standard 4 kw fixed rooftop array. however, investments for the solar flower are about 50% bigger compared to similar size rooftop solar panel system. smartflower buyers pay a price premium for the folding, self-cleaning, and aesthetic benefits of the smartflower over competing alternatives (smartflower solar: the complete review 2017). fig. 4. pv tree and solar flower (producers photos). 3. non-technical possibilities and barriers for res and pv systems in different countries many developments over the last few years have affected the deployment of res, including the lowest prices of pv systems, the decision of several countries to become coal-free, new policies and partnerships, carbon pricing, and new initiatives and goals set by governments at all levels. nontechnical possibilities and barriers for res and pv systems in different countries many developments over the last few years have affected the deployment of res, including the lowest prices of pv systems, the decision of several countries to become coal-free, new policies and partnerships, carbon pricing, and new initiatives and goals set by governments at all levels. the european union and lithuania case the european union (eu) res directive (2009/28/ec) sets a binding target of 20% final energy consumption from renewable sources by 2020. to achieve this, the eu countries have committed to reaching their own national renewables targets ranging from 10% in malta to 49% in sweden. the 2017 report states that the eu totally achieved 16% share of res in 2014. in 2016, the estimated share of res in the eu’s gross final energy consumption was 17% (the progress of each country will be fully assessed in the coming months). the vast majority of eu countries are well on track to reach their 2020 binding targets for res (european commission, 2018). for example, lithuania have reached 23% share of res in 2014. public interventions such as support schemes remain necessary to make certain res technologies competitive. to avoid distorting energy prices and the market however, these schemes should be time-limited and carefully designed. the eu has issued guidance on support schemes to help governments when they design or revise support schemes (european commission, 2018). for example, in lithuania, some limited subsidy systems and funds for res installations exist since 2005. depending on a project, it is possible to apply for a subsidy covering from 30 to 100% of initial costs. for example, it is possible to get a subsidy up to 30 % for a single-family building, up to 40% for a multifamily building and up to 100 % for hospitals and public buildings. development of domestic pv (≤ 10 kwp) systems is now one of the government targets in lithuania. since the end of 2017, the installation of grid connected pv systems in single-family houses are much simpler than before. it takes only up to 2 months for systems up to 5 kwp and up to 6 months for pv systems up to 10 kwp. price reduction of pv systems and government support helped to grow installations of residential pv systems. philippines case in a developing country like the philippines, access to energy is necessary to alleviate the economic status of the land as well as improving the lives of the poor. the philippines is estimated to have a population of 102 million people and is considered a fast-growing economy in the world. in journal of sustainable architecture and civil engineering 2018/2/23 34 this regard, a huge amount of power is needed to sustain the economy. coal is the main fuel used in the philippines, therefore the philippines is considered to be the highest in asia when it comes to electricity costs. this establishes the potential of shifting to renewable energy. locals are investing in pv panels and batteries for a simple light load. in addition, the philippine government also committed to reduce carbon emission by 70% by 2030 and targeted 15.3gw of renewable energy. to promote the development of solar power in the philippines, the government introduces the net metering regulations. india case india is projected to be the world’s fastest-growing large economy for the rest of the decade, according to projections from the world bank and the international monetary fund. it will also soon be the world’s largest country by population. india is generating around 20.1% of the total generation through renewable sources. india has set an impressive target to generate 175gw through renewable sources by 2022; 100gw through solar, 60 gw from wind, 10gw from biomass and waste and 5gw through small hydro. out of 175 gw, 62.84 gw has been achieved till december 2017 (mnre annual report 2017-18). a national solar mission was launched under the national action plan on climate change on june 30, 2008. the government has set a massive target of 100gw under the national solar mission. to achieve the goal, the indian government has started many schemes and programs under various categories of solar projects, from big pv parks to small rooftop and off-grid installations; for example, solar park scheme, defense schemes, solar water pump scheme etc. not only that but, the central government of india is also providing financial assistance, starting from 30% to 60% subsidy on the rooftop pv plants and 60% to 70 % on solar water pumps to promote solar energy. to accelerate the program government also gave targets to the organizations and states and introduced net metering. as a result, the cost of solar power has come down drastically, i.e., usd 0.36/ unit. indonesia case indonesia is the world’s fourth largest country by population, encompasses more than 17000 islands. indonesian growing need for energy security due to gradual depletion of fossil-based energy sources demands renewable, affordable and omnipresent energy sources. one of the most anticipated ways to secure the future country energy supply is to use the energy from the sun, which is delivered to earth in a formed light or electromagnetic radiation. in this regard, a photovoltaic device is especially of wide interest as they can directly convert sun’s visible light into electricity. taking into account the indonesian geographical advantage where the solar irradiation is relatively unchanged in the values of 4.75-5.98 kwh/m2/day throughout the year (rumbayan et al. 2012), pv would inevitably be of an essential part of country’s electricity source. in this regard, indonesian government has launched presidential regulation no. 79/2014 to reduce significantly the use of oil to below 20% and to increase the contribution of res from 0.5% to more than 5%. in 2014, the energy mix in indonesia for fossil fuels and res were 94% and 6% while it is projected that the national energy mix target in 2025 for fossil fuels and res are 75%, and 25% (ministry of energy and mineral resources of the republic of indonesia 2014). however, so far only 20 mw were installed in 2014 and in 2015 the first utility-scale plants were connected to the grid. in early 2016 the government announced a 5 gw plan to develop pv in the country (trends 2016 in photovoltaic applications, 2016). seychelles case seychelles as any other small island developing states, for generation of electricity rely on imported fossil fuel; about 95% of used fuel is imported and it covers more than 10% of the national 35 journal of sustainable architecture and civil engineering 2018/2/23 annual budget, not to mention concerns on the impact to climate change. the national energy policy sets a target of achieving 5 % res deployment by 2020 and 15 % by 2030. currently seychelles have 6 mw capacity of wind turbines installed in two reclaimed islands and about 2.8 mw grid tied distributed rooftop pv systems. presently a lot of projects are being developed in the country to reach the targets and the development of utility scale pv system on a sea water lagoon is considered. the seychelles res market is accelerated by policy changes, established strong regulatory framework, improved capacity and financial incentives supporting the access to more renewable sources with limited land availability. other technical concerns such as intermittency of resources, grid limitations, fluctuation and forecasting systems must be properly discussed and solved. the plan to explore other res in marine are also on going but so far only in the research and development. 4mw floating pv plant in the providence lagoon will be the first such project in country. peru case in 2016 peru generated 10.8% from res (small hydro, biomass, wind and solar) of its total 48.3 twh. large hydro accounted for 39.8%, natural gas for 46.4%, and coal, oil and diesel for the rest. to promote res, peru offers priority dispatch and 20% accelerated depreciation for renewables projects. peru has one of the highest solar resources in the world, receiving 2,050-2,550 kwh/m2 of solar irradiance per year. the opportunities for solar are diverse, with potential in large grid connected projects and mid-sized off-grid projects in mining and industry. rural electrification also offers an opportunity for small scale solar pv. peru, one of the first countries in the word, held an auction for off-grid solar in november 2014 to contract up to 500,000 off-grid pv systems to be installed in north, center and south regions. the auction had only one winner, the private developer ergon, which announced the intention to install 150,000-200,000 systems. on march 2018, the peruvian government declared the opening of rubí, the largest solar power plant in the country that boasts over half a million solar panels with a production capacity of 145mw. according to the study (pucp 2017) in 2017 over 500,000 homes in peru had no access to electricity, that was much more prevalent in rural areas. through the national rural electrification plan, it is planned to provide over 345,000 homes with pv panels in the near future. peru goal of reaching 99% electrification by 2021 involves the installation of small scale pv systems for remote households without grid access. it is planned to invest 385$ million for this purpose. however, despite these advancements, peru is still lagging behind its south american neighbors when it comes to res. future challenges of pv systems development over the recent decades environmental concerns have pushed up res revolution. recently the research trends of pv systems are mainly focused on improving reliability, efficiency and power quality, reducing the cost, integrating with a grid at various scales and contributing to building microgrid and smart grid paradigms. the future trend of pv is promising with the objective of becoming one of the first energy producers of the world. the future of pv development strongly depends on efficiency and cost of solar modules. the usage of new materials to create multijunction solar cells will lead the future in this field. speaking about the solar pv power inverters, the focus will always be on maximizing the efficiency of converter with minimum cost. reliability, fault-tolerant operation, easy maintenance, reduced transportation and installation costs are also factors in developing new power converter topologies for pv systems, from low to high power. in addition, the stochastic behavior of the sun irradiation, the grid stability requirements, and the maximization of economical profits will possibly force us to use energy storage installations supjournal of sustainable architecture and civil engineering 2018/2/23 36 porting pv installations to save extra energy if a power curtailment is required or adding active or reactive power if the grid demands it. the development of battery technology by improving their lifetime, efficiency and reducing their weight, size and costs will walk hand in hand with this hybrid solution. another aspect, which can significantly improve future perspective of solar energy is broad development of dc smart grids as well as research on smart transformers (liserre et al. 2016). this trend makes easy integration and full utilization of pv energy and storage elements possible, which eliminates additional power converters and improves overall efficiency and energy security. finally, yet importantly, the vast development of pv systems also strongly depends on governments and a strong support required developing and implementing res. in the past tariff policies accelerated the development of the res technology. now, the political efforts have to be focused on creating a friendly scenario to create a distributed electrical grid system not very dependent on gas/coal-based or nuclear plants. discussion and conclusions in recent years all over the world pv systems have become very competitive solutions for residential, commercial, and industrial applications for both standalone and grid connected operations. in a lot of countries, the grid-connected solar pv is the promising technology for solving future energy demands. the researches related to pv currently concentrate on the improvement and solutions for higher efficiency and lower price of the pv panels and systems, extracting the maximum possible amount of energy from the pv panels. the best performing monocrystalline silicon models have about 26,7% efficiency. the high concentration multijunction solar cells achieved up to 46.0% efficiency in the laboratory. there is still much research and development needed in this direction. recorded efficiencies demonstrate the need for further efficiency improvement at the production level. this is a major challenge for future research to increase 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doi.org/10.1109/icept.2015.7236590 anju singh researcher national institute of solar energy, department of solar thermal main research area solar thermal address gurugram, haryana 122003, india tel. +91 880 044 0147 e-mail: anshihari@gmail.com anies mutiari researcher center for material and technical product, ministry of industry of republic indonesia main research area emerging material for photovoltaics address jl. sangkuriang 14 bandung west java indonesia 40135 tel. +62 22 2504088 e-mail: anies-m@kemenperin.go.id cynthia alexander principal officer seychelles energy commission main research area: renewable energy, energy efficiency in buildings, efficient appliances, standards and labeling, energy auditing address po box 1488, palms street, victoria, mahe, seychelles tel. +248 2723459 e-mail: calexander@sec.sc diana arteta de la cruz researcher pontifical catholic university of peru main research area: renewable energy for the development of rural communities. address av. universitaria 1801, san miguel, lima 32 peru tel. +511944264875 e-mail: diana.arteta@pucp.edu.pe federico e. del pozo jr lecturer industrial technology development institute of science and technology main research area energy management, renewable energy, energy engineering, electrical engineering, ergonomics, work measurement address dost compound, gen. santos avenue bicutan, taguig city, philippines, 1631 tel. +632 837 2071 e-mail: fedjr14@gmail.com rokas valancius lecturer kaunas university of technology, department of building energy systems main research area renewable energy, indoor climate, energy performance in buildings address studentu st. 48, lt-51367 kaunas, lithuania tel. +37068010000 e-mail: rokas.valancius@ktu.lt mailto:anshihari@gmail.com mailto:anies-m@kemenperin.go.id mailto:calexander@sec.sc mailto:diana.arteta@pucp.edu.pe mailto:fedjr14@gmail.com mailto:rokas.valancius@ktu.lt journal of sustainable architecture and civil engineering 2016/3/16 46 *corresponding author: georgekourti@eac.com.cy assessment of the social electricity online platform tools and their potential impact on european citizens http://dx.doi.org/10.5755/j01.sace.16.3.15803 george kourtis*, ioannis hadjipaschalis electricity authority of cyprus, amfipoleos st. 11, 2025 strovolos, nicosia, cyprus andreas kamilaris department of computer science, university of cyprus, panepistimioupolis, 1678, nicosia, cyprus maria solomou centre for the advancement of research & development in educational technology, lykavitou ave. 29, 1st floor, 2401, nicosia, cyprus received 2016/07/28 accepted after revision 2016/09/26 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 46-60 doi 10.5755/j01.sace.16.3.15803 © kaunas university of technology assessment of the social electricity online platform tools and their potential impact on european citizens jsace 3/16 through the social electricity online platform (seop) european project, four learning modules, educational content and online eco-feedback platforms have been developed, to raise the awareness and knowledge of citizens about energy, the environment and sustainability. the platform allows european citizens to become educated on energy-saving practices and techniques, including the use of renewable technologies at their home. moreover, through the social electricity application, people may become aware of their electrical energy consumption by means of comparisons with the corresponding electrical consumption of their friends, as well as with the total consumption in the street, neighbourhood, village, city and country where they live, in a collaborative and social environment. in this paper, a pilot study performed in eight european countries involving more than 300 european citizens is presented, in order to demonstrate the influence of online learning modules and ecofeedback platforms on the everyday lives of people, in terms of rational energy use and energy savings. in this pilot, participants have been divided into two groups: the former uses the four learning modules available on the seop platform and then the social electricity application, whereas the latter uses only the social electricity application. this paper describes our overall findings after three months, exploring the completeness and educational value of the learning modules, and the potential of social electricity as an effective online tool for personal energy management. the results also evaluate the impact, behavioural change and the increase on energy awareness among the two groups, as well as the general effectiveness and acceptance of the platform. keywords: adult learning, energy management, good practices, ict platform, social electricity. 47 journal of sustainable architecture and civil engineering 2016/3/16 without a doubt, concerns on environmental protection due to the high greenhouse gases emissions is today a key driver for the global need for electrical energy saving. nowadays, people realize that the electricity they use originates mainly from coal or hydrocarbon-based power plants, which emit carbon-dioxide which is severely harmful to humans and the environment. moreover, energy should be conserved since we are consuming a disproportionate amount of energy and that day is not far when all our non-renewable energy fuel resources will be exhausted forcing us to rely just on renewable sources (bhattacharya 2014). apart from the above, electrical energy saving also helps electricity consumers to save money and mitigates the numerous adverse environmental and social impacts associated with energy production and consumption. these include air pollution, acid rain and global warming, oil spills and water pollution, loss of wilderness areas, construction of new power plants, foreign energy dependence and the risk of international conflict over energy supplies. in addition, proper energy use extends the lifetime of electrical equipment and reduces the maintenance cost by operating less hours and at less than maximum capacity (gavaskar et al. 2012). european citizens need to understand the political, social and environmental implications of energy consumption and dedicate their efforts to consume energy more rationally (leonard 2010). a crucial issue that hinders the awareness of citizens about energy is the absence of effective information and communication technology (ict) infrastructures that would help people to perceive the effects of their actions on the physical and urban environment (kat 2010). unfortunately, current ict platforms that aim to educate people about energy conservation are rather isolated and incomplete, not based on any methodological and analytical techniques (mankoff et al. 2010), (egan 1999). an example that highlights this inadequacy is the fact that in most european countries, people receive an electricity bill only once every month (in some countries even once every two months), and they cannot understand whether their electrical consumption is low, medium or high. this could be only addressed by ict platforms that present electricity-related information to citizens in real-time, allowing them to compare their consumption with the past, and also with their neighbors or friends, in order to make more informed choices about their personal consumption. in order to tackle these issues, the social electricity online platform (seop) research project has been created with the promise of developing a social ict platform that allows european citizens to be educated about energy saving practices and techniques, helping them to perceive the crucial importance of energy conservation for the society and the environment (social electricity application, 2012)– (seop project, 2013). seop consists of a high-quality consortium, merging the experience of the university of cyprus acquired during the design and deployment of social electricity application, together with the expertise of other partners (cardet, ecc, integra and qualed) in the domain of learning and education. a critical aspect for the success of the project and the maximization of its content quality and exploitation is the participation of public and private energy and electricity agencies from europe such as eac, krea and miema. in addition, the community-based organization meath partnership infuses to the project the elements needed to be effective and practical in local/communal level. finally, the university of athens assists the development procedures with its knowledge in analysis of internet applications and online social networking. the project has two main objectives, on one hand to help people to become more energy aware and to conserve energy and on the other to develop new learning strategies and techniques to educate people effectively towards environmental sustainability. in this paper, the seop project and the online tools of the seop platform are presented in section 2. further, in section 3, a pilot study performed in eight european countries involving more than 300 european citizens is described, demonstrating the influence of online learning modules and eco-feedback platforms on the everyday lives of people, in terms of rational energy use and energy savings. the results of the pilot test are presented in section 4, whereas the conclusions are summarized in section 5. introduction journal of sustainable architecture and civil engineering 2016/3/16 48 the seop project (seop project, 2013) has been funded by the lifelong learning programme of the european commission, aiming to develop a social ict platform that allows european citizens to be educated about energy saving practices and techniques and the crucial importance of energy conservation for the society and the environment. the project has two main objectives, on one hand to help people to become more energy aware and conserve energy and on the other to develop new learning strategies and techniques to educate people effectively towards environmental sustainability. the former goal has been approached by applying state of the art methodologies and pedagogical approaches to influence people to acquire a more sustainable, green lifestyle. these methodologies and approaches have been implemented through various modules, which will educate people about rational energy management and use. the latter aim has been approached by observing, analyzing and experimenting with the applied methodologies and their design elements, in order to assess each of them, identifying their advantages/weakness, and choosing the ones that prove to be more effective. these methodologies/features/elements have then been integrated to the online tools developed through the project. another important objective of the project was to encourage people to engage themselves in energy saving practices, forming communities related to sustainability and proper use of energy, increasing their willingness to help other people to become more sensitive about energy and about their physical and urban environment. people have been encouraged to contribute to the community by expressing their experience and expertise in energy saving efforts, sharing with others their best practices for energy conservation and rate other people’s approaches for energy conservation. seop platform has a pedagogical character based on state of the art methodologies relating to adult education and persuasion (fogg 2003). the pedagogical approach of the online learning platform is based on the latest developments in the field of adult training and e-learning (mankoff 2007). the platform hosts four learning courses for educating citizens on issues related to home energy management, proper use of domestic electrical appliances, as well as use of renewable technologies such as photovoltaics and wind turbines. finally, the project extends the award-winning social electricity facebook application (kamilaris et al. 2012a), (kamilaris et al. 2015) (kamilaris et al. 2016a), an online application which helps people to manage their personal consumption in a social and collaborative environment, by interacting and comparing their footprint with friends, neighbors and other users, analyzing and setting goals for future savings. learning modules seop platform has been enriched with four learning courses for educating citizens on issues related to home energy management, proper use of domestic electrical appliances, as well as use of renewable technologies, as shown in fig. 1. in order for a user to complete the online modules, he needs to register to the platform and create an account (seop project, 2013). each module has separate units which are graded with end-of-course questions. by successfully completing the tests/questions of all the four courses, the user receives a certificate, signed by the consortium of seop. the first module concerns digital literacy, and prepares users to apply basic knowledge regarding digital participation in online spaces. the users are introduced to online etiquette rules, as well as to various social media tools for communication, such as facebook and twitter. with this module, the users are also trained on how to effectively use the various tools of seop, in order to increase their knowledge on energy, electricity and sustainability and to be able to properly manage, compare and improve their daily energy consumption. the seop project 49 journal of sustainable architecture and civil engineering 2016/3/16 fig. 1 seop learning modules the second module is about energy management, providing awareness about the global need for electrical energy management and energy savings. the module provides a background on the eu policies for energy management and some good practices that can be used to achieve energy savings in houses or office environments. also, with this module, users can become familiar with energy management techniques that can be used in daily life and learn what can be gained by applying some of these energy management techniques at their own home. moreover, participants are able to learn about the main renewable energy technologies that exist at the market today. the third module is named green solutions and green practices, aiming to increase citizens’ knowledge on various electricity saving opportunities regarding household electrical appliances, as well as on the use of the most energy efficient lighting solutions and to introduce the most promising renewable energy technologies that can be used in the household for local production of electricity, such as small photovoltaic systems and small wind turbines. finally, the fourth module constitutes a user manual for the social electricity application, assisting the users to register and use the social application, which is described in the following sub-section. social electricity application as mentioned above, the seop project extends the award-winning social electricity facebook application (shown in fig. 2), which helps consumers to perceive their energy behaviour by comparing their footprint with the one of their online friends and other contacts (kamilaris et al. 2012a), (social electricity application 2012). social electricity aims to raise the energy awareness of users by exploiting social norms, normative social influence, personalization and various eco-feedback services, which have proved to be effective in related work (froehlich 2010), (he 2010), (kamilaris 2013). it allows people to collaborate and exchange know-how and experiences in the domain of home energy management, towards the co-creation of knowledge and more informed choices that may lead to energy savings. journal of sustainable architecture and civil engineering 2016/3/16 50 detailed domestic consumption data from all around cyprus is provided by the electricity authority of cyprus (eac), for the last three years. respecting the privacy of citizens (kamilaris et al. 2016b), the electricity measurements are aggregated at street level (address, postal code and city). from this data, users can select the average consumption of their street as their personal consumption, or they can add their own consumption each month, as shown in fig. 3 (kamilaris et al. 2012a). comparisons can be performed among facebook friends, citizens living at the same street, town/ village, or users sharing similar house characteristics (e.g. house size and type, heating/cooling method etc.), as illustrated in fig. 4. users can also compare their consumption with the average one of their local street. rankings are offered about the most energy-efficient streets and villages near the user’s location, motivating people to acquire “region awareness”, inspired to take actions to help the local community maintain a better ranking. temporal comparative feedback is supported too, in regard to previous months and for the same month in previous years. users may also compare with their friends’ temporal patterns. besides the main features, social electricity gives useful tips to people to save energy and become more educated about best energy-saving practices. other features include competitions fig. 2 social electricity application fig. 3 privacy of users 51 journal of sustainable architecture and civil engineering 2016/3/16 fig. 4 fair comparisons with similar peers around your country for savings, learning material about green practices, online educational social games relating to energy, statistics about the areas, villages and towns with the least/most energy consumption around the country and the option to associate electricity with actual costs, enabling users to have a more meaningful view of their energy profile. comparisons and rankings are presented by means of easy-to-understand graphs, with consumption and price fig. 5 breakdowns of total consumption to individual appliances figures. moreover, users can add their personal electrical appliances and declare how they use them (e.g. specs, frequency, time of use, consumption), and then view analytical breakdowns of their overall monthly consumption according to the particular, seasonal use of their home devices, as illustrated in fig. 5. after three years of operation, the application counts more than 2000 active users in cyprus and more than 750 users around the rest of europe. during the summer months of 2015, a large pilot study was performed in the countries of the project partners (cyprus, greece, ireland, malta, lithuania, austria, slovenia and slovakia), in order to evaluate seop and its online products (learning modules and social electricity application) on their effectiveness and acceptance regarding influencing the european citizens for more rational use of energy and reduction of their personal footprints. in the pilot study, 335 european citizens have participated from the aforementioned 8 countries. the participants were divided in two groups. the first group completed the four learning modules before using the social electricity application, while the second group used only the social electricity application (in order to assess the impact and usefulness of the modules themselves). each group at each country consisted of at least 30 participants. the participants needed to fill three questionnaires (before, in the middle and after the pilot study). pilot study methodology journal of sustainable architecture and civil engineering 2016/3/16 52 the first questionnaire was about the users’ energy consumption habits before the treatment methods, as well as their beliefs towards the environment (captured through 22 parameters, see table 3) (poortinga et al. 2004). these parameters may characterize people’s quality of life (qol) and their attitudes/behaviours related to the environment (personal, social, economical and physical). the second questionnaire was completed only by the participants of the first group, and related to the evaluation of the learning modules with respect to their quality, educational value and completeness. the third questionnaire was completed at the end of the pilot by the participants of both groups and was very similar to the first one, asking about the participants’ energy consumption habits, as well as the aforementioned 22 qol parameters. the aim of the first and third questionnaire was to capture any influence of the study on the participants’ behaviours and habits. furthermore, the final questionnaire included an overall evaluation of the acceptance and effectiveness of the social electricity application. regarding the recruitment procedure, the partners of the seop project contacted their friends, relatives and colleagues or students aged 20 to 70 years face to face or by telephone, to explain the project and the importance to participate in the pilot testing process. then, the partners exchanged emails with their participants regarding the pilot test categories in order to derive the most appropriate category for them to participate, based on the time they could spend on the pilots or their overall interest to become more engaged in the pilot tests. the partners tried to divide people in groups a and b equally (without informing them about the existence of the other group), to avoid possible biases such as gender, age, area of living, income etc. finally, the partners gave instructions to the participants about (a) how to participate in the different categories of the pilot tests, (b) about the questionnaires they had to fill and (c) the deadlines for submitting them. for the purpose of this paper, only 157 participants out of the 335 participants (who completed the first questionnaire) have been considered, as only those have answered all the questionnaires, participating at the pilots till their end. by comparing these 157 subjects, we can make some results table 1 pilot test participants’ age age (years) percentage (%) 20-25 12 26-30 15 31-35 21 36-40 22 41-45 15 46-50 9 over 50 6 conclusions about the participants’ behaviour before and after the study. the reasons that some participants did not answer all the questionnaires are described in section 4.5. the results of the analysis are described in the following sections. comparison of behavioural change in this analysis, 157 participants from eight counties (cyprus, greece, ireland, malta, lithuania, austria, slovenia and slovakia) who have answered both the first and third questionnaires have been considered. tables 1 and 2 show the age and educational level of the participants. it can be observed that although there was a variety of the age and the education of the participants of the pilot study, most of them were of age from 26 up to 45 and with a bachelor or a master degree. from those participants, 74% had up to one cooling fan in their home, 76% had up to 2 heaters and 75% had up to one air conditioner in their house, as illustrated in fig. 6. from those having heaters in their house, it can be observed from fig. 7 that there has not been significant change in their behaviour regarding the operational mode of the heater, which remains between 22oc and 24oc for table 2 pilot test participants’ education education (degree) percentage (%) lyceum 1 technical training 13 bachelor 29 master 42 p.h.d. 9 other 6 53 journal of sustainable architecture and civil engineering 2016/3/16 fig. 6 heating and cooling systems fig. 7 heater mode around 85% of the participants. fig. 8-11 show the behavioural change of the participants regarding their habits which affect the electricity consumption of their house, before and after the study. specifically, there was an improvement after the study, regarding the use of open windows when the fans are working during the day in summer, as 72% have rarely or never open windows compared to the respective 66% before the study. furthermore, there was a change in the use of open windows when the heater is on, as 59% of the participants have rarely or never open windows after the study compared to the respective 55% as declared before the study. as for open windows during the operation of air conditioners, there was a slightly worse situation after the study, as 5% of the participants who never open windows before the study, after the study they rarely open the windows. the results were improved regarding the use of daylight, turning off the lights when nobody is in the room or leaving the lights on even when there is daylight outside the house, as shown in fig. 8 and fig. 9. specifically, there was 6% improvement of using more frequently the daylight after the study, 9% improvement of turnfig. 8 behavioural change of participants’ habits before the study (part 1) journal of sustainable architecture and civil engineering 2016/3/16 54 ing off more frequently the lights when nobody is in the room and 5% improvement of not leaving the lights on even when there is daylight outside the house. moreover, by observing fig. 10 and fig. 11, there was an improvement in the behaviour of the participants after the study regarding (a) leaving home appliances on standby than switching them off, (b) having computers switched off after 30 minutes of inactivity and (c) unplugging the chargers after using them. specifically, an additional 18% of the participants after the study were rarely or never leaving the home appliances on stand by mode, an additional 9% of the participants switched off their computers after 30 minutes of inactivity and an additional 7% unplugged their chargers after use, compared to the respective numbers before the study. also, the participants learned during the pilot test to save energy by using their refrigerator properly (an improvement of 15%), as they now always cool their food before storing it. an improvement of 3% of the participants was also observed as now they always cover the liquids before storing them in the refrigerator. fig. 9 behavioural change of participants’ habits after the study (part 1) fig. 10 behavioural change of participants’ habits before the study (part 2) fig. 11 behavioural change of participants’ habits after the study (part 2) 55 journal of sustainable architecture and civil engineering 2016/3/16 as for the environmental concern of the participants regarding having access to clean air, water and soil and to enjoy natural landscapes, parks and forest, it can be observed from fig. 12 and fig.13 that either an improvement or neither a deterioration has been occurred after the study and the only conclusion that can be made is that the participants became more neutral on this matter. changes in quality of life parameters regarding the changes on the attitudes of the participants in relation to the 22 qol parameters the (poortinga et al. 2004) through the pilot, table 3 lists these parameters, along with the change on peoples’ attitudes on each of them. as we mentioned before, the 22 parameters characterize people’s fig. 12 behavioural change on environmental issues before the study fig. 13 behavioural change on environmental issues after the study quality of life and their behaviours related to the environment (personal, social, economical and physical). in the table, positive/negative change in attitude is calculated as an increase/decrease in the people’s score before and after the study, on a 5-scale likert-style answer (1: no influence, 2: little influence, 3: some influence, 4: much influence, 5: large influence). obviously, there is a positive increase in the attitudes of the participants towards their quality of life and the environment, in all the 22 qol parameters. the metrics with the largest influence were aesthetic beauty, challenge/excitement, change, comfort, material beauty, security, spirituality/ religion and social status. we also noticed that participants of group a had slightly larger scores in comparison to the participants of group b, something that indicates that the learning modules have somehow influenced this positive change. effectiveness of learning modules as it is mentioned before, the second questionnaire targeted to get feedback about the opinion of the group of users who completed the learning modules before using the social electricity application (i.e. the first group), in order to understand the effectiveness of the learning modules on helping the participants in saving energy. from fig. 14, it can be observed that most of the participants were pleased with the content of the learning modules, as 63% of them answered that the information was well organized and presented, 71% of them answered that the language was clear journal of sustainable architecture and civil engineering 2016/3/16 56 and 59% answered that the questions captured important topics. however, almost half of them didn’t find the navigation easy and didn’t find the content of the videos, animations and images very helpful. moreover, almost half of the participants found this learning method more convenient compared to traditional learning methods, as illustrated in fig. 15. no. metric change in attitude (%) 1 aesthetic beauty: being able to enjoy the beauty of nature and culture 29.2 2 challenge/excitement: having pleasant and exciting experiences 29 3 change: having a varied life, experiencing many things as possible 35.2 4 comfort: having a comfortable and easy daily life 29.6 5 education: having the chance to get good education and general knowledge 24 6 environmental quality: having access to clean air, water and soil 16 7 freedom: freedom and control over the course of one’s life 18.4 8 health: being in good health, access to adequate health care 20.8 9 identity: having sufficient self-respect, being able to develop one’s identity 21.6 10 leisure time: having enough time after work, spending this time nicely 24 11 material beauty: having nice possessions in and around the house 28 12 money/income: having enough money to buy and to do pleasing things 24 13 nature/biodiversity: to enjoy natural landscapes, parks and forests 20 14 partner/family: having an intimate relation and a stable family life 25.6 15 private: having opportunities to be yourself and do your own things 21.6 16 safety: being safe at home, protected against criminality 24 17 security: feeling attended to and cared for by others 28 18 social justice: having equal opportunities and rights as others 20 19 social relations: good relationships with friends, colleagues and neighbours 24.8 20 spirituality/religion: live a life with an emphasis on spirituality 32 21 social status: being appreciated and respected by others 30.4 22 work: having or being able to find a job and fulfil it as pleasantly as possible 27.2 table 3 influence of the pilots: qol metrics fig. 14 learning modules quality parameters 57 journal of sustainable architecture and civil engineering 2016/3/16 as to how the participants were assisted to become more aware of energy conservation by using the learning modules, it can be observed from fig. 16, that more than half of them became more aware of the topic after studying the learning modules. effectiveness of the social electricity application the third questionnaire also had some questions for the participants regarding the social electricity application’s quality and effectiveness. specifically, around 65% of the participants were satisfied with the effectiveness, the usefulness and the user-friendliness of the application, whereas 62% and 71% of the participants were positive regarding the potential and the design of the application, as illustrated in fig. 17. furthermore, the application influenced 77% of the participants to become more aware about their personal consumption, whereas 86% of the participants were optimistic about the future potential of the application, as shown in fig. 18. lessons learned from the pilot study procedure although the users were at the beginning very keen to participate, they were not very engaged with fig. 15 learning modules convenience fig. 16 energy conservation awareness fig. 17 quality parameters of social electricity application journal of sustainable architecture and civil engineering 2016/3/16 58 the tests’ timetables and needed to be reminded through several emails and phone calls. all participants were also receiving frequent, automatic reminders through the application. one important reason for the moderate engagement was the complicated registration process, especially for the first group, where participants had to register with personal details twice; fig. 18 effectiveness parameter of social electricity application once for the learning modules in the platform and then again for the social electricity application. also, in some countries, there was a problem with some participants understanding the procedure which was at first only in english (translation in the local context took place in the middle of the pilot) and there was a need for personal advice or electronic communication at their local languages. another important reason for the low engagement was the timing of the pilot testing. the first group had a deadline before the summer holidays, which is usually a busy period for all european citizens. this meant that some of the users couldn’t finish all the modules in time since they needed more time to go through all of them. also, since the second part of the pilot tests (the use of the social electricity application), started during the summer period for both groups, many of the users did not submit their home consumption reading (from the electricity meter) in the application, as they were on holidays. moreover, an overwhelming majority of participants criticized the number of very personal questions (income, but also personal beliefs), and it required a lot of energy (and time) to explain the rationale and persuade them to continue with the testing. in this work, a pilot study performed in 8 european countries involving more than 300 european citizens is presented, to demonstrate the influence of online learning modules and eco-feedback platforms on the everyday lives of people, in terms of rational energy use and energy savings. in this pilot, participants have been divided into two groups. the former uses the four learning modules of the platform and then the social electricity application, whereas the latter uses only the application. the study shows that there has been a small improvement between 5%-10% on the participants’ habits related to the electricity consumption in their house, during the period of the pilot study. on some habits, the improvement has been even larger, around at 15%. however, for some habits, deterioration or neutral attitude has been observed. as for the effectiveness of the learning modules, it has been observed that most of the participants are pleased with their content, finding this method very convenient. the only drawbacks of the learning modules, according to the participants, were that the navigation was not easy and they didn’t find the content of some videos, animations and images very helpful or relevant to their particular needs. regarding the effectiveness of the social electricity application, most of the participants were pleased with the quality of the application and stated that the application made them become more aware of their personal consumption. 59 journal of sustainable architecture and civil engineering 2016/3/16 considering the overall findings of this study, it becomes evident that eu countries should promote and facilitate the integration of smart meters in consumers’ houses (kamilaris 2010), (kamilaris et al. 2012b), with regulatory decisions, so the consumers could improve their electricity consumption by observing consumption data of their electrical appliances in real time, getting more visibility and details on their personal footprint, and take more informed everyday decisions. smart metering should be accompanied by ict supporting technologies, such as mobile and web applications, carefully designed to offer context-relevant education and proper eco-feedback, considering well-accepted and effective persuasive techniques such as normative social influence, personalization, goal setting, challenge and rewards, exploiting the crowd wisdom for co-creation of new knowledge and sharing of know-how and experiences. finally, this pilot revealed (through the qol metrics) that citizens are influenced positively towards the environment when ict applications consider, respect and promote their aesthetic beauty, challenge/excitement, change, comfort, material beauty, security, spirituality/religion and social status. hence, policy makers and eco-feedback application designers need to take into serious consideration these parameters when designing the green ict apps of tomorrow. this work was supported in part by the lifelong learning programme of the european union, contract no. 543375-llp-1-2013-1-cy-ka3-ka3mp. acknowledgment bhattacharya t., sustained growth of green energy economics, international journal of inventive engineering and sciences, 2014, 2 (4): 16-18. egan c., graphical display and comparative energy information: what do people understand and prefer? in proceedings of the summer study of the european council for an energy efficient economy, 1999. fogg b.j., persuasive technology: using computers to change what we think and do, morgan kaufmannn, 2003. froehlich j., findlater l., and landay j., the design of eco-feedback technology, in proceedings of the sigchi conference on human factors in computing systems, chi ‘10, pages 1999–2008, new york, ny, usa, 2010. acm. https:/doi.org/10.1145/1753326.1753629 gavaskar j. j., pillai v. p., sanker n. k., et all, energy economics study on biomass energy conversion techniques, international journal of research in mechanical engineering & technology, 2012, 2 (1): 49-54.he h. a., greenberg s., and huang e. m, one size does not fit all: applying the transtheoretical model to energy feedback technology design, in proceedings of the sigchi conference on human factors in computing systems, chi ‘10, pages 927– 936, new york, ny, usa, 2010. acm. kamilaris a., trifa v., guinard d., building webbased infrastructures for smart meters, in energy awareness and conservation through pervasive applications workshop, in proc. of pervasive 2010, helsinki, finland, may 2010. kamilaris a., taliadoros g., papadiomidous d., pitsillides a., the practice of online social networking of the physical world, international journal of spacebased and situated computing, 2012, 2 (4): 240-252. https:/doi.org/10.1504/ijssc.2012.050007 kamilaris a., tofis y., bekara c., pitsillides a. and kyriakides e., integrating web-enabled energy-aware smart homes to the smart grid, international journal on advances in intelligent systems, 2012, 5(1 & 2): 15-31. kamilaris a., kitromilides g., pitsillides a., energy conservation through social competitions in blocks of flats, in proc. of the 1st international conference on smart grids and green it systems (smartgreens), porto, portugal, april 2012. kamilaris a., pitsillides a., fidas c., kontebudi s., social electricity: the evolution of a large-scale, green ict social application through two case studies in cyprus and singapore, ict for sustainability conf., copenhagen, denmark, sep., 2015. kamilaris a., pitsillides a., fidas c., social electricity: a case study on users perceptions in using green ict social applications, international journal of environment and sustainable development, 2016, 15 (1): 67-88. https:/doi.org/10.1504/ijesd.2016.073336 references journal of sustainable architecture and civil engineering 2016/3/16 60 kamilaris a., pitsillides a., kondepudi s., komninos n., privacy concerns in sharing personal consumption data through online applications. in proc. of the 12th international wireless communications & mobile computing conference (iwcmc), paphos, cyprus, september 2016. https:/doi.org/10.1109/iwcmc.2016.7577124 kat a., ehrhardt-martinez d., laitner j. a., advanced metering initiatives and residential feedback programs: a meta-review for household electricity-saving opportunities, research report e105, american council for an energy-efficient economy, 2010.leonard a., the story of stuff: how our obsession with stuff is trashing the planet, our communities, and our health-and a vision for change, simon and schuster, 2010. mankoff j., fussell s. r., glaves r., et al., stepgreen. org: increasing energy saving behaviours via social networks, 4th international association for the advancement of artificial intelligence conf. on weblogs and social media, 2010. mankoff j., matthews d., fussell, s. r. and johnson m., leveraging social networks to motivate individuals to reduce their ecological footprints. in proceedings of the 40th annual hawaii international conference on system sciences (hicss ‘07), washington, dc, usa, 2007. ieee computer society. https:/doi.org/10.1109/hicss.2007.325 poortinga w., steg l., vlek c., values, environmental concern, and environmental behavior a study into household energy use, environment and behaviour, 2004, 36 (1): 70-93. https:/doi.org/10.1177/0013916503251466 social electricity application, 2012. online at: http:// www.social-electricity.com/ seop project, 2013. online at: http://www. seop-project.eu/ george kourtis electrical engineer, general manager office electricity authority of cyprus main research area generation development plan, tariff methodology and new electricity market rules. address amfipoleos street 11, 2025 strovolos, nicosia, cyprus tel. 0035722201529 e-mail: georgekourti@ eac.com.cy ioannis hadjipaschalis electrical engineer, general manager office electricity authority of cyprus main research area res, distributed generation, electricity distribution networks, hydrogen and co2 capture and storage (ccs) technologies. address amfipoleos street 11, 2025 strovolos, nicosia, cyprus tel. 0035722201523 e-mail: ioannishadjipashalis@ eac.com.cy andreas kamilaris senior postdoc researcher university of cyprus, faculty/department: department of computer science main research area web technologies, online social networking, ecofeedback. address department of computer science, university of cyprus, panepistimioupolis, p.o. box 20537, nicosia, cy 1678, cyprus tel. 003579922892686 e-mail: kami@cs.ucy. ac.cy maria solomou lead instructional designer, project manager cardet main research area e-learning, design of interactive trajectories within online social spaces, 2d and 3d, online social learning. address 29 lykavitou avenue, 1st floor, 2401, nicosia, cyprus tel. 0035722002118 e-mail: maria. solomou@cardet.org about the authors 57 journal of sustainable architecture and civil engineering 2017/1/18 corresponding author: vaiva.vaitkeviciute93@gmail.com ecological cleaning and reusing of wastewater. possibilities, advantages and proposals received 2016/11/20 accepted after revision 2017/02/10 journal of sustainable architecture and civil engineering vol. 1 / no. 18 / 2017 pp. 57-64 doi 10.5755/j01.sace.18.1.17557 © kaunas university of technology ecological cleaning and reusing of wastewater. possibilities, advantages and proposals jsace 1/18 http://dx.doi.org/10.5755/j01.sace.18.1.17557 vaiva vaitkevičiūtė*, kamilė jakubauskaitė, jurga vitkuvienė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania introduction the historical view of sewage and rainwater cleaning, possibilities of applying it nowadays and newest experience in the world are analyzed in the article. the main advantages and disadvantages of the system were revealed after research. there were two parts of the analysis: personal cleaning and territorial planning. biological and mechanical filtration were mostly used types of water cleaning. main problems of ecological cleaning and reusing of wastewater were found: rather high price, possible permanent damage to the soil. keywords: ecological cleaning, bioretention, ecological engineering, graywater, sewage farm, wastewater treatment. only 1% of all water on earth is usable freshwater. today, we take clean, treated water, utilize it once and then flush it away. there are plenty of possibilities to clean wastewater, even more, reuse it ecologically. applying natural ecologic processes to wastewater filtering is one of the most innovative solutions for common contamination problem. ecological engineering is important not only for decreasing physical and chemical pollution, even more, it creates beneficial conditions for functioning of natural and anthropogenic eco-systems, moreover, it improves environmental quality (biodiversity, social value, aesthetical view, etc.). although, not many of wastewater cleaning possibilities are being used in lithuania and other countries. one of the main ecological engineering principles is to solve problems by applying various models of eco-systems. although similar projects and ideas were known even in the ancient times, the notion of ecological engineering and the main principles were formulated only in the middle of the 20th century. around 1970 the huge wastewater cleaning projects, based on principles of ecological engineering, were started in america. (kadlec, 2009, bastian, 1993, the arcata...) applying ecological engineering technologies requires high qualification of the engineers and builders, because of that first projects received various reactions and discussions of citizens and specialists. inappropriate evaluation of ecological risk (jorgensen, 2014), incorrect technical decisions and a lot of other factors (kangas, 2004, etnier, 1996) can easily make a lot of unexpected problems (uncontrolled pollution flow, bad smell, ineffective cleaning process, etc.). moreover, those problems cannot be easily solved – it requires a lot of effort and investment (jorgensen, 2014). even more, this kind of wastewater treatment occupies a relatively big area, which is designed for sedimentajournal of sustainable architecture and civil engineering 2017/1/18 58 tion pools and filtration fields systems. this might be a reason which withholds the development of this kind of engineering systems. ecological engineering and its field of use is extremely important part of sustainable development (campbell, 1999). in the time of rising life quality and society needs and consciousness, the attitude to usage of various engineering systems changes. despite of these main causes, especially lightly contaminated wastewater, called greywater, cleaning by using treatment wetlands is one of the most perspective ecological engineering realms, which is now becoming widely used all over the world. plenty of projects of this technology, evaluated with highest-level awards, such as asla (american society of landscape architects), were established in china, usa, canada, netherlands and other well-developed countries these year. this technology only takes its first steps in lithuania and it is not well-known between designers, engineers and architects. although, there are few initiatives in small ecological engineering objects designing, such as eco-pools. ecological treatment of wastewater and rain water could completely or partially change common industrial wastewater cleaning equipment, which damages aesthetical view and it is declared as the objects of visual pollution. ecological engineering and architecture, which connects various needs of community and nature into one system, could be the great example of applying sustainable development to everyday life. the aim of this article is to present various ways to clean the wastewater, their advantages, field of use; to research the examples from abroad and propose different areas and aspects of wastewater purification and potential of applying it in lithuania. furthermore, it is important to highlight the main problems of applying these systems, to understand, why these techniques are not widely used. the method of this article is comparative literature analysis. the article is based on an overview of the historical development of the issue. historical survey includes the origins of the water treatment method and discusses some typical cases of practice of this method in different historical periods. as well as touches upon the problems which have been encountered in the operation of such facilities or evaluating their impact on the environment. the second part analyses the latest wastewater treatment experience, discusses some examples of using modern technology in projects of varying scale and character, from huge areas to application of these principles in the level of local private facilities. even in prehistoric times there were three main aspects people had to deal with to be able to grow plants: how to concentrate desirable plants into one convenient place; to prevent unwanted weeds from growing there; and to find the best solution to encourage the plants to thrive. in short, people had to learn how to plant, weed, and water or drain crops. although, there was no such thing as wastewater treatment, it gave a fundament to its development in the future. irrigation based agriculture has been the technology created by many of the world’s greatest civilizations, although it was used in many different ways (angelakis 2015, wiesmann… 2006, pescod, 1992). one of them was application of its principles to the waste water treatment. but invention like this is not easy to develop. usually, ancient irrigation schemes require a lot of investment or labor or both, moreover, it depends on physical geography and geology of the area and requires a lot of engineering skills. most known irrigation systems were developed in ancient egypt, mesopotamia (coven, 1999), but one of the oldest and most developed centralized sewage management system examples were set in mohenjo daro culture. furthermore a similar cases can be found all over the world (angelakis 2015). in middle ages the facility of water cleaning was forgotten. the change of morals and social habits had a huge influence on everyday life. privacy of the family and household became essential, because of that the public lavatories that were used in roman empire were no more appropriate. although monasteries tried to solve this problem by creating some internal and common lavatohistorical experience 59 journal of sustainable architecture and civil engineering 2017/1/18 ries, the idea was ignored by the communities. the main solution was to throw sewage straight to the street and let it flow away to the nearest pond or river. (angelakis, rose, 2014). after the industrial revolution and the rapid growth of the cities sanitation problems became vital. therefore it was searched for various ways of solving them. among those decisions was an attempt to adapt the ancient water management methods based on the principles of irrigation. ancient experience was taken as a base for these days needs and improved for a different specialization. the irrigation system was applied to wastewater filtering. the main similarity between these water using systems is water ponds, sometimes in different levels, where water flows naturally. berlin example sewage farm in berlin is one of the earliest examples of wastewater treatment. it was designed using j. hobrechts dewatering concept. the base of hobrechts system was to divide the city into 12 districts, called radial systems, each of it had a pumping station. domestic, commercial and industrial wastewater flew into these stations as well as precipitation water through gravity flow pipelines. the main purpose of pumping stations was to collect wastewater from districts and to redirect it to sewage farms located outside the city. wastewater is first collected in sedimentation basins, where water flows through the tank and most sediments settle to the bottom. dewatered sludge had been used as a soil conditioner for agriculture and horticulture in early years. there were three types of sewage farm (fig. 1) treatments in berlin: catchment (horizontal), bed and slope. each of them are applied depending on surface. “horizontal terraces are flooded by surrounding distribution ditches. for slope terraces, sewage water overflows the upper bank and irrigates the sloped terrace. bed terraces with ditch irrigation were also initially used. waste water flowed through bed terraces in connected parallel furrows, about one meter apart. only plant roots received water.” (goedecke, welsch, zweer, 2000) after using this system for a long time, it was realized that by cleaning hardly contaminated water all the harmful sedimentations stay in the soil. hence this system would be better for graywater (lightly contaminated used water) cleaning (goedecke, welsch, zweer, 2000). sydney example before intermittent downward filtration was used in sydney, it was widely applied in towns and cities of the great britain and the united states of america, where land was often scarce and the ocean distant. hence situation was a bit different in the newly established city of sydney. australian method used land as a filter through which the sewage drained, because of this the land became richer and crops could be grown. although, this was only secondary consideration since the main purpose was to purify wastewater before it reached the ocean (wastewater network…). now the wastewater network in sidney consists of 30 separate systems; 24 000 kilometres of fig. 1 types of sewage farms (with reference to berlin environmental atlas…2016, ehrhardt s. et al. 1991) journal of sustainable architecture and civil engineering 2017/1/18 60 pipes; 16 wastewater treatment plants and 680 pumping stations. most of the work is done by a gravity – it makes wastewater flow naturally through catchment drainage lines to a wastewater treatment plant (beder, 1993). after long time of using filtration fields, it was noticed that a lot of toxic sedimentations stay in approximately small area, which cannot be cleaned for a long time. it was decided that this kind of filtration system should be applied only for low-polluted wastewater, called graywater. lithuanian case in terms of application experience in lithuania of this type of technology, should be mentioned practices of filtration fields development that have been introduced in some advanced farms during interwar period. but then lack of experience and knowledge and the insufficient perception of processes of natural environment and human impact on them in most cases had a negative impact on the surrounding environment (filtering fields were installed in grounds which were not suitable for that or too close to the surface water bodies, etc.). even the larger effects on the environment were caused by the use of filtration fields in the soviet period. then not only domestic but also industrial waste were treated in this way. at this industrial period the extra precautions had not been taken and thus it caused to recover not only large but also very dangerous quantities of waste that has accumulated in certain limited areas, which is currently very difficult to use. this causes the questions for the liquidation of negative consequences even today (panevėžys…2011). for these reasons and negative experiences quite a negative view of the open-type wastewater treatment methods is formed in lithuania and their application in practice is very limited. these days wastewater treatment technology became widely used in more fields and countries. as it has improved, it became necessary to divide sedimentations into individual groups to increase cleaning effectivity. generally, wastewater treatment could be categorized into levels (including preliminary, primary, secondary and tertiary or advanced treatment criterions), based on activities made in these stages. in preliminary treatment stage, only debris (paper, plastic materials, rags, etc.), which can be taken away even physically, are being cleaned from the wastewater. primary stage involves the partial elimination of suspended solids and organic materials from wastewater physically by screening and sedimentation. the main purpose of secondary treatment is to get rid of organic solid material using bacterial decomposition. tertiary treatment eliminates inorganic components from the wastewater (orukpe otaigbe, 2010). nowadays wide used alternative wastewater cleaning technology is based on water cleaning, when plants are used as a filter, has some similarities to a simple biological cleaning. it is based on each plant having its own sewage treatment area. this type of water cleaning should be called filtering as sedimentations area cleaned by roots of the plants and this process is absolutely natural and self-contained. at the moment the method of wastewater treatment, imitating the principles of natural processes occurring in the natural environment it is rapidly becoming popular. it has some positive aspects, which contribute to the anthropogenic activities in the natural environment and might implement sustainable development strategies. these different alternative wastewater treatment method application areas can also be distinguished: landscape as a living system. simulation of natural processes in anthropogenic geotechsystems is currently widely applied in spatial planning. it helps to organize the complex of human activities in large, heavily used territories or to eliminate of the negative effects of human activities in the affected environment. industrial area by the huangpu river in shanghai was remade to demonstrate ecological culture for expo 2010. houton park is a regenerative landscape and was designed to treat polluted river water and recover degraded river waterfront in an attractive way. moreover, wetland not only filters river water, it even protects the area from the flood. this kind of ecology attracts people to visit common technologies of biological wastewater cleaning 61 journal of sustainable architecture and civil engineering 2017/1/18 and to take a walk around the area by well-developed pedestrian paths. potsdam square. hobrecht’s sewage farm was not the only example of wastewater treatment systems in berlin. this idea was improved and newly established in potsdamer platz (potsdam square) (fig. 2). the aim of this project is to collect rainwater and to filter it through percolation beds which include aquatic plantings. all the water of the system circulates through filtration beds every third day. “regular monitoring of key parameters such as ammonia nitrogen, nitrites, nitrates and phosphorus shows a high level of water quality quite suitable for fish and other wildlife” (overstrom, 2008). fig. 2 potsdam square, berlin. rainwater management (photo by j.vitkuvienė) fig. 3 scheme of water collection, storage and use of the daimler crystler center in potsdam square (according to glücklich, 2013) this project is not only ecological, it even increases aesthetical view of this square. the water flows through shallow ponds and watercourses along the square, moreover, people can cross them by stepping on stones and enjoy the nature view in the city centre (overstrom, 2008). the main idea of this urban project is that the rainwater is used where it falls. to achieve that, water is collected from the roofs of 19 buildings in this area, most of them are covered by grass. greenest neighbourhood. the application of modern environmental uses is important not only for the sustainability and preservation of the natural environment and protection of anthropoecosystems, but also for improvement of the quality of living environment and aesthetic. neighbourhood in victoria, british columbia (canada) is sometimes called the greenest neighbourhood in the world – it is carbon-neutral and it is achieved by using on-building windmills, solar panels and, the most important, biomass gasification plant. moreover, it has established its own sewage treatment system and graywater recycling facilities. the technological process of the water cleaning is used to make this neighbourhood look more attractive – the stream is running through the development and it makes an illusion that everything is built on the water (benfield, 2011). gulbinų district in vilnius. this is one of the first examples of non-traditional storm water management technology implemented in lithuania. the main purpose in this district nearby vilnius was to increase recreational potential and to design ponds for rainwater cleaning. the area was 1 ha (with 55 percent of urbanisation), so it would require to have 190 m3 reservoir to collect rainwater. the main purpose of this design was to find an alternative between filtration pond and device. the result was a scheme of rainwater management network and places of ponds in this neighbourhood. these ponds are cleaning rainwater both ways – biologically and mechanically. the main idea of this type of cleaning is water transportation from bigger manifold to the leading pond journal of sustainable architecture and civil engineering 2017/1/18 62 through periodically suffused bay, which is distinguished from leading pond by a dam. technology of cleaning by ponds is based on water gathering in lower parts of territory. from there it starts to go deeper into the soil and it is collected in underground reservoirs. after that, water is lead to the surface ponds. by the time water filters through the soil, it gets treated mechanically, later on surface it is cleaned biologically by plants. in this kind of ponds, it is hard to remove oil products from rainwater – this is the reason, why it was necessary to place oil catchers near large parking lots. moreover, it requires a lot of attention – lowland needs to be cleaned up periodically (januška, 2015). it is possible not only to take care of water cleaning globally (in districts, towns and cities), but also in small private areas. rain gardens and eco-pools also can be used as instrument for improving the quality of living environment and solving the issues of wastewater and storm water management that are particularly relevant for lithuanian cities. eco-pools (natural swimming pools) are results/main problems and possible proposals for lithuania the alternative to widely used chlorine or salt pools. system of this pool is based on water flow circle: water is being pumped and flows through the roots of various plants – this is the way it gets cleaner. there are three different areas in this kind of pond: swimming area, plants area that filters water and slope shore area that makes water get warmer and regenerates it (fig. 4, 5). the soil of plants area consists of these layers: well-drained planting soil, sand and gravel bed. all these layers are located on the foundation of the existing soil. pool like this does not require a lot of attention and is completely natural. although it is more popular in abroad, there are a few examples of eco-pools in lithuania. specialist of landscape architecture g. jablonskienė created one, matching all these criterions, in private house aside vilnius. as a new technology, it is rather expensive, although, it is a good investment into future because of its natural circulation and self-cleaning abilities. fig. 4 work scheme of eco-pool fig. 5 example of eco-pool in potsdam square (photo by j.vitkuvienė) summarizing the examples, we can distinguish the following problems of the main alternative ways of water management practices: _ if not applied correctly, this kind of treatment could make damage to the soil and contaminate its deepest layers. although it is possible to filter sewage water, it could leave permanent damage to the soil as berlin example demonstrates. _ proper application of these measures in practice requires a lot of theoretical preparedness, knowledge and systematic understanding of the principles of ecology, and their exact implementation in projects. 63 journal of sustainable architecture and civil engineering 2017/1/18 _ it is quite expensive method, requiring investments. _ districts, like in china (houton park) or canada (victoria, british columbia), have to connect to a river or to be generally aside the water. reorganization of abandoned industrial districts by the rivers is a noticeable problem in lithuania. a newly formed district would have its own sewage system, which could make the whole district’s wastewater treatment autonomic. filtered graywater could be returned to the river or reused by households. nowadays in lithuania there are many renovation projects in process which could be improved by wastewater treatment principle of the potsdam square or rain gardens. the rain water could be collected from the roofs of apartment buildings and be treated in the system underground. moreover, the filtration fields with fountains and flowing water streams could bring to life currently abandoned district yards. collected rain water could be used for inside household usage, such as toilets, washing machines, etc. as well as to become a measure for improving the aesthetic quality. 1 although wastewater usage technologies have old traditions, this kind of wastewater treat-ment is not widely used in lithuania. society should be introduced to possibilities of ecological engineering; its well-known problems and technological solutions. 2 renovation projects in lithuania could be improved by using the principles of ecological engineering in sewage systems. 3 usage of ecological engineering principals would help to assimilate and make abandoned districts attractive, even more, to update ordinary renovation projects. 4 the application this kind of green idea would make a decent difference not only for a par-ticular district but also for a whole city. 5 rain gardens and eco-pools could be firstly designed in public spaces. hence municipality of each town or city should be a good example for citizens. this kind of example would convince people to try something new. even more, taking care of usual pools in lithuania is quite a challenge for an owner. hence the pool which is self-sufficient could be a free choice for every household. conclusions angelakis a. n., rose j. b. evolution of sanitation and wastewater technologies through the centuries. iwa publishing, london; 2014 angelakis a. n., zheng x. y. evolution of water supply, sanitation, wastewater, and stormwater technologies globally. water 2015, 7, 455-463. issn 2073-4441 www.mdpi.com/journal/water bastian r. k. constructed wetlands for wastewater treatment and wildlife habitat. 17 case studies. united states. environmental protection agency, 1993. available at: http://www.epa.gov/owow/ wetlands/pdf/constructedwetlands-complete.pdf (accessed on august 26 2015) beder s. from sewage farms to septic tanks: trials and tribulations in sydney. journal of the royal australian historical society, vol. 79, parts 1 and 2, 1993, pp. 72-95. available at: https://www.uow.edu. au/~sharonb/sewage/history2.html benfield k., 2011. is this the world’s greenest neighbourhood? available at: http://www.theatlantic. com/international/archive/2011/08/is-this-theworlds-greenest-neighborhood/244121/ (accessed on 22 august 2015) berlin: water creates a vibrant cityscape. available at: http://www.dac.dk/en/dac-cities/sustainable-cities/ all-cases/water/berlin-water-creates-a-vibrant-cityscape/ (accessed on 22 august 2015) berlin environmental atlas. 01.10 sewage farms. data base: urban and environmental information system (ueis) senate department for urban development and housing. available at: http://www. stadtentwicklung.berlin.de/umwelt/umweltatlas/ ed110_02.htm campbell c.s., ogden m.h. constructed wetlands in the sustainable landscape. 1999 john willey and sons. 270 p. coven r., 1999. exploiting the earth (chapter 17: ancient irrigation). available at: http://mygeologypage. ucdavis.edu/cowen/~gel115/115ch17oldirrigation. html (accessed on 22 august, 2015) etnier c., guterstam b. ecological engineering for wastewater treatment. 1996. lewis publishing. 443 p. references journal of sustainable architecture and civil engineering 2017/1/18 64 ehrhardt s. et al. 1991: altlastenerkundung in pankow am beispiel der rieselfelder, bericht über die projektarbeit bei der utb, gesellschaft für informationstechnik, umwelt und betriebsberatung, berlin. glücklich d. fundamentals of ecological planning and building, 2013. available at: <http://www.ecobine.de/print.php?sessid=5d7092d85d384778d6c3226dcb5d3204&id=3.6.1&kurs=11&l=en> goedecke m., welsch j., zweer r. 01.10 rieselfelder [01.10 sewage farms]. beteiligte am umweltatlas berlin. senate department for urban development and the environment urban and environmental information system, berlin; 2000 jablonskienė g., 2013. natūralus baseinas – šimtu procentų [natural pool – one hundred pool]. available at: http://gyva.lt/articles/view/242 (accessed on 24 august 2015) januška l., kaunas z., kazickas r., zabilius v, 2015. darnios miestų plėtros hidrologiniai aspektai, aprobuoti planuojant vilniaus miesto gulbinų rajono teritoriją. kraštovaizdžio architektūra – profesijos horizontai ir sinergija. kraštovaizdžio architektūros forumo ’2015, vykusio vilniuje 2015 m. spalio 29 d., mokslo darbai. 238-247 p. jorgensen s.e., chang n.b, xu f.l. ecological modelling and engineering of lakes and wetlands. elsevier, 2014. 665 p. kadlec r.h. wallace s.d. treatment wetlands. 2nd ed., 2009 crc press. 1016 p. kangas p.c. ecological engineering. principles and practice. lewis publishers, 2004 natural swimming pools & ponds (no chemicals). available at: https://www.totalhabitat.com/natural-swimming-pools.html (accessed on 24 august 2015) nuotekų filtravimo sistemų įrengimo aplinkosaugos taisyklės. patvirtinta lietuvos respublikos aplinkos ministro 2001 m. gegužės 9 d. įsakymu nr. 252 (lietuvos respublikos aplinkos ministro 2012 m. balandžio 2 d. įsakymo nr. d1-281 redakcija) available at: https://www.e-tar.lt/portal/lt/legalact/tar.57f737b1a208/szqjodiabs orukpe otaigbe s, 2010. municipal wastewater treatment with special reference to the central waste water treatment plant in poznan, poland. available at: http://www.theseus.fi/bitstream/handle/10024/12650/orukpe_otaigbe.pdf?sequence=1 (accessed on 24 august 2015) overstrom n., 2008. potsdamer platz. available at: http://people.umass.edu/latour/germany/noverstrom/ (accessed on 22 august 2015) panevėžyje bus valomi sunkiaisiais metalais užteršti laukai. available at: http://www.alfa.lt/ straipsnis/12955152/panevezyje-bus-valomi-sunkiaisiais-metalais-uztersti-laukai pescod m.b. wastewater treatment and use in agriculture fao irrigation and drainage paper 47, 1992. food and agriculture organization of the united nations rome. available at: http://www.fao.org/ docrep/t0551e/t0551e00.htm#contents shanghai houtan park: landscape as a living system. available at: http://www.asla.org/2010awards/006. html (accessed on 28 august 2015) the arcata marsh and wildlife sanctuary. the restoration project. available at: http://therestorationproject.weebly.com/current-operations-and-land-use. html (accessed on 26 august 2015) wastewater network. available at: https://www.sydneywater.com.au/sw/water-the-environment/howwe-manage-sydney-s-water/wastewater-network/ index.htm (accessed on 29 august 2015) wiesmann u., choi i. s., dombrowski e.m. 2006. fundamentals of biological wastewater treatment. willey, 391 p. isbn: 978-3-527-31219-1, https://doi. org/10.1002/9783527609604 vaiva vaitkevičiūtė student kaunas university of technology, faculty of civil engineering and architecture main research area architecture address studentu st. 48, lt-51367 kaunas, lithuania tel. +37061929352 e-mail: vaiva.vaitkeviciute93@gmail.com kamilė jakubauskaitė student kaunas university of technology, faculty of civil engineering and architecture main research area architecture address studentu st. 48, lt-51367 kaunas, lithuania tel. +37069031898 e-mail: j.kamile93@gmail.com jurga vitkuvienė lector kaunas university of technology, faculty of civil engineering and architecture main research area architecture address studentu st. 48, lt-51367 kaunas, lithuania tel. (8 37) 45 15 46 e-mail: jurga.vitkuviene@ktu.lt about the authors 13 journal of sustainable architecture and civil engineering 2015/2/11 journal of sustainable architecture and civil engineering vol. 2 / no. 11 / 2015 pp. 13-20 doi 10.5755/j01.sace.11.2.11008 © kaunas university of technology maryna öztürker lutsk national technical university, faculty of construction and design artseulov st. 32/9, 43021 lutsk, ukraine corresponding author: maryna.ozturker@gmail.com maximum free flow capacity and factors affecting it http://dx.doi.org/10.5755/j01.sace.11.2.11008 jsace 2/11 maximum free flow capacity and factors affecting it received 2015/02/25 accepted after revision 2015/06/01 city is a dynamic organism and communication between its parts is provided by a circulatory system – an urban road network. its proper functioning can be organized only when the road network capacity is sufficient for the traffic value. precise assessment of roadway capacity and understanding of its nature are still the actual questions as there are various approaches but a reliable and meaningful estimation method is still not identified for today. the method based on fundamental diagram and first car-following model allows evaluating the impact of a number of factors on maximum free flow capacity and has been chosen for this purpose. coefficient of road adhesion φ and driver’s perception-reaction time t’ are determined as the most influencing factors what gives the directions for the following studies in capacity increase. the earliest car-following model created a branch of genealogical model tree and is still included in its ancestor versions used in traffic simulation software. keywords: degree of influence, factors, maximum free flow (theoretical or design) capacity. how much traffic can the road carry? the answer to this question has been of interest since 1920s when the first studies of road capacity estimation have been conducted (may 1990). capacity of facility (hcm 2000) is defined as the maximum hourly rate at which persons or vehicles reasonably can be expected to traverse a point or a uniform section of a lane or roadway during a given time period under prevailing roadway, traffic and control conditions. estimation of capacity is necessary for: _ design of new facilities (number and width determination of lanes); _ identifying the areas with unsatisfactory functioning for new developments; _ evaluation of traffic efficiency; _ choice of traffic regulations and control types; _ assessment of service levels and operational characteristics. according to v. babkov (1993), there are two types of capacity: _ maximum theoretical, which is determined for ideal conditions; _ and practical that reflects actual traffic conditions. introduction journal of sustainable architecture and civil engineering 2015/2/11 14 methods other classification of capacity was given elsewhere (minderhoud et al. 1997): _ design capacity is used for planning and designing roads (maximum theoretical as in the classification above); _ strategic capacity as maximum traffic volume a segment can handle, which might be useful for conditions analysis in road networks (its value is derived from capacity distribution); _ operational capacity (actual maximum value) is assumed to be useful in representing the dynamic nature of flow rate in real conditions and in short-term forecasting for determination of traffic control measures. due to importance of capacity estimation in roadway design and traffic control different approaches were created. in the study (minderhoud et al. 1997), these methods were grouped into direct empirical (based on observed headways, volumes, speeds and densities) and indirect empirical (based on guidelines or simulation models) categories. the first category represents the stochastic estimation methods. guidelines in the second one are based on deterministic approach. as for simulation, the traffic flow models contain deterministic and stochastic levels in its formulae, what makes it closer to real traffic on the roads. the conservative capacity concept (in guidelines such as hcm 2000; dbn v.2.3-4:2007; dbn v. 2.3-5-2001) is based on free-flow diagram and represents the reasonable expectancy of maximum flow rate at the locations with similar conditions (roadway parameters, traffic volumes and control measures) (kittelson et al. 2001). in this case capacity is a constant value and its obvious stochastic nature is ignored. recent studies (elefteriadou et al. 2001; 2003; 2006) represented stochastic capacity analysis methods which are based on field observation results and show that freeway capacity is a random variable even under constant roadway conditions. the concept of traffic breakdown probability is used for freeway capacity determination. the maximum observed volume in certain period of time, after which traffic breakdown is observed, is considered to be the capacity of facility. stochastic methods use the capacity distribution function to calculate the probability of traffic breakdown for different volume represented on the freeway. nowadays traffic simulation software is widely used by traffic engineers. it is based on different microscopic car-following models which reflect stead-state and non-steady-state behaviour of traffic flow. steady-state component mostly determines: desirable speed for different traffic volumes and capacity of facility. the second component describes the traffic behaviour between steady-state conditions applying acceleration and deceleration models (rakna et al. 2011). in this study the focus will be on the method which is applied for calculations of the maximum free flow (theoretical or design) capacity of one lane on a uniform segment in ukraine. it is based on fundamental diagram (the relationship between three variables q (traffic volume), space-mean speed v and density k) and the earliest car-following model (pipes 1953; forbes 1958). this approach gives us an opportunity to follow the influence of a number of factors it considers and its routes are tracked in traffic simulation models on the steady-state level. the maximum free flow (theoretical or design) capacity per one lane of uniform segment without intersections, on the straight and horizontal section is determined by a formula: where: k – is density (pc/km); v – is design speed of motion (m/s); l – is conditional value that provides a safe distance, which is enough for complete braking of a car when the ahead going car has stopped (m). (1) strategic capacity as maximum traffic volume a segment can handle, which might be useful for conditions analysis in road networks (its value is derived from capacity distribution); operational capacity (actual maximum value) is assumed to be useful in representing the dynamic nature of flow rate in real conditions and in short-term forecasting for determination of traffic control measures. due to importance of capacity estimation in roadway design and traffic control different approaches were created. in the study (minderhoud et al. 1997), these methods were grouped into direct empirical (based on observed headways, volumes, speeds and densities) and indirect empirical (based on guidelines or simulation models) categories. the first category represents the stochastic estimation methods. guidelines in the second one are based on deterministic approach. as for simulation, the traffic flow models contain deterministic and stochastic levels in its formulae, what makes it closer to real traffic on the roads. the conservative capacity concept (in guidelines such as hcm 2000; dbn v.2.3-4:2007; dbn v. 2.35-2001) is based on free-flow diagram and represents the reasonable expectancy of maximum flow rate at the locations with similar conditions (roadway parameters, traffic volumes and control measures) (kittelson et al. 2001). in this case capacity is a constant value and its obvious stochastic nature is ignored. recent studies (elefteriadou et al. 2001; 2003; 2006) represented stochastic capacity analysis methods which are based on field observation results and show that freeway capacity is a random variable even under constant roadway conditions. the concept of traffic breakdown probability is used for freeway capacity determination. the maximum observed volume in certain period of time, after which traffic breakdown is observed, is considered to be the capacity of facility. stochastic methods use the capacity distribution function to calculate the probability of traffic breakdown for different volume represented on the freeway. nowadays traffic simulation software is widely used by traffic engineers. it is based on different microscopic car-following models which reflect stead-state and non-steady-state behaviour of traffic flow. steady-state component mostly determines: desirable speed for different traffic volumes and capacity of facility. the second component describes the traffic behaviour between steady-state conditions applying acceleration and deceleration models (rakna et al. 2011). in this study the focus will be on the method which is applied for calculations of the maximum free flow (theoretical or design) capacity of one lane on a uniform segment in ukraine. it is based on fundamental diagram (the relationship between three variables q (traffic volume), space-mean speed v and density k) and the earliest car-following model (pipes 1953; forbes 1958). this approach gives us an opportunity to follow the influence of a number of factors it considers and its routes are tracked in traffic simulation models on the steady-state level. methods the maximum free flow (theoretical or design) capacity per one lane of uniform segment without intersections, on the straight and horizontal section is determined by a formula: 3600  vp kv l , (passenger cars per hour per lane) (1) where k – is density (pc/km); v – is design speed of motion (m/s); l – is conditional value that provides a safe distance, which is enough for complete braking of a car when the ahead going car has stopped (m). (passenger cars per hour per lane) 15 journal of sustainable architecture and civil engineering 2015/2/11 first models based on safe following distance l were proposed by l. a. pipes (1953) and t. w. forbes (1958). this theory is based on the following statements and applies for fairly dense traffic: _ value of the capacity p is calculated in passenger cars, equivalents of which are used to take into account the differences of dynamic size of trucks, buses, rvs and other vehicle types; _ the flow of vehicles is considered uniformly distributed; _ all vehicles move with constant speed v = const without overtaking (konoplyanko 1991). since then scientists proposed the formulae that differ by determination of time interval between the start of braking of two vehicles moving one after another and braking factor c. as for nowadays application of pipes-forbes car-following model, there are several microscopic simulation software in which different steady-state behaviour is identical to it. among them there are corsim (pitt model; based on vehicle spacing and speed differential between the lead and following car), vissim (wiedemann74 and 99 models, action point or psychological model), paramics (fritzsche model, action point or psychological model) and integration (van aerde model, nonlinear functional form). detailed study on this topic was done elsewhere (rakha et al. 2002; 2003; 2011). for this research the formula of safe distance will be used that is specified in the works of d. samoilov and e. dubrovin (samoilov et al. 1981; dubrovin et al. 1981): this method allows us to determine the degree of influence on roadway capacity of such factors as: speed v, longitudinal slope i, coefficient of road adhesion φ, coefficient of rolling resistance f, driver’s perception-reaction time t’ and clearance l 2 . for this purpose the reference design capacity should be taken under ideal conditions. its value is calculated by formulae 1, 2 for i=0, t’=1 s, f=0.01 – for asphalt concrete in good condition, φ=0,7 – for dry rough surface, v=60 km/h (16.67 m/s) – design speed for arterial roads in the cities with population in range 100,000 – 250,000 citizens according to table 7.1 dbn 360-92** (state construction standard of ukraine), l 2 = 2.5 m. where: l 0 – is length of the car, m; t’ – is driver’s perception-reaction time of the rear car after the front one starts braking, s; (2) first models based on safe following distance l were proposed by l. a. pipes (1953) and t. w. forbes (1958). this theory is based on the following statements and applies for fairly dense traffic: value of the capacity p is calculated in passenger cars, equivalents of which are used to take into account the differences of dynamic size of trucks, buses, rvs and other vehicle types; the flow of vehicles is considered uniformly distributed; all vehicles move with constant speed v = const without overtaking (konoplyanko 1991). since then scientists proposed the formulae that differ by determination of time interval between the start of braking of two vehicles moving one after another and braking factor c. as for nowadays application of pipes-forbes car-following model, there are several microscopic simulation software in which different steady-state behaviour is identical to it. among them there are corsim (pitt model; based on vehicle spacing and speed differential between the lead and following car), vissim (wiedemann74 and 99 models, action point or psychological model), paramics (fritzsche model, action point or psychological model) and integration (van aerde model, nonlinear functional form). detailed study on this topic was done elsewhere (rakha et al. 2002; 2003; 2011). for this research the formula of safe distance will be used that is specified in the works of d. samoilov and e. dubrovin (samoilov et al. 1981; dubrovin et al. 1981):      r f 2 0 2 v k + к l = l + vt + + l , 2g f ± i + f (2) where l0 – is length of the car, m; t′ – is driver’s perception-reaction time of the rear car after the front one starts braking, s; g – is acceleration due to gravity, m/s2; кo=кr+кf – is coefficient of operating braking conditions of rear and front cars introduced by prof. d. velikanov; φ – is adhesion coefficient of automobile tire with road surface; f – is coefficient of rolling resistance for roads with different types of pavement at normal air pressure in a pneumatic tire; і – is road longitudinal slope; l2 – is clearance (reserve safety segment between the cars after their stopping), m. this method allows us to determine the degree of influence on roadway capacity of such factors as: speed v, longitudinal slope i, coefficient of road adhesion φ, coefficient of rolling resistance f, driver’s perception-reaction time t′ and clearance l2. for this purpose the reference design capacity should be taken under ideal conditions. its value is calculated by formulae 1, 2 for i=0, t'=1 s, f=0.01 – for asphalt concrete in good condition, φ=0,7 – for dry rough surface, v=60 km/h (16.67 m/s) – design speed for arterial roads in the cities with population in range 100,000 – 250,000 citizens according to table 7.1 dbn 360-92** (state construction standard of ukraine), l2 = 2.5 m. g – is acceleration due to gravity, m/s2; к o =к r +к f – is coefficient of operating braking conditions of rear and front cars introduced by prof. d. velikanov; φ – is adhesion coefficient of automobile tire with road surface; f – is coefficient of rolling resistance for roads with different types of pavement at normal air pressure in a pneumatic tire; і – is road longitudinal slope; l 2 – is clearance (reserve safety segment between the cars after their stopping), m. (3)   r 2 3600×16,67 p = = 1248 16,67 ×1,2 5 +16,67×1+ + 2,5 2× 9,81 0,7 +0,011 (pc/h/l) (3) fv=0,01[1+0,01(60-50)]=0,011 speed v. let us consider how the capacity p will be changing with speed v in the range from 10 up to 100 km/h. the maximum value of capacity obtained at speed v=30 km/h – p=1376 pc/h, the minimum one – at v=10 km/h – p=914 pc/h (fig. 1). when the speed exceeds 30 km/h, the capacity begins declining gradually due to a rapid rise of the braking distance s length, in the numerator of which formula the speed is squared; fig.1. dependence of capacity p from speed v coefficient of road adhesion φ. let us consider how the capacity p will be changing when the ratio of the coefficient of road adhesion φ will be in the range from 0.05 up to 0.95. the maximum value is obtained when φ=0.95 – p=1434 pc/h for dry crushed stone pavement processed by organic binders, the minimum – at φ=0.05 – p=198 pc/h for pavement covered with ice (fig. 2). the capacity increases, when road surface is dry and rough (respectively value of coefficient of road adhesion φ rises) and decreases, when it is wet and smooth (values of the coefficient are smaller, since on the surface of a street or a road a film from dust and water is formed, that worsens gripping of wheels of the car to the roadway surface); fig. 2. dependence of capacity p from coefficient of road adhesion φ rolling resistance coefficient f. let us consider how the capacity p will be changing when rolling resistance coefficient f will be in the range from 0.005 up to 0.3. the maximum value is obtained when f=0.3 – p=1476 pc/h, the minimum – at f=0.005 – p=1244 pc/h (fig. 3). journal of sustainable architecture and civil engineering 2015/2/11 16 _ speed v. let us consider how the capacity p will be changing with speed v in the range from 10 up to 100 km/h. the maximum value of capacity obtained at speed v=30 km/h – p=1376 pc/h, the minimum one – at v=10 km/h – p=914 pc/h (fig. 1). when the speed exceeds 30 km/h, the capacity begins declining gradually due to a rapid rise of the braking distance s length, in the numerator of which formula the speed is squared; _ coefficient of road adhesion φ. let us consider how the capacity p will be changing when the ratio of the coefficient of road adhesion φ will be in the range from 0.05 up to 0.95. the maximum value is obtained when φ=0.95 – p=1434 pc/h for dry crushed stone pavement processed by organic binders, the minimum – at φ=0.05 – p=198 pc/h for pavement covered with ice (fig. 2). the capacity increases, when road surface is dry and rough (respectively value of coefficient of road adhesion φ rises) and decreases, when it is wet and smooth (values of the coefficient are smaller, since on the surface of a street or a road a film from dust and water is formed, that worsens gripping of wheels of the car to the roadway surface); _ rolling resistance coefficient f. let us consider how the capacity p will be changing when rolling resistance coefficient f will be in the range from 0.005 up to 0.3. the maximum value is obtained when f=0.3 – p=1476 pc/h, the minimum – at f=0.005 – p=1244 pc/h (fig. 3). as well as in the case of the coefficient of road adhesion φ, increasing of the rolling resistance coefficient f leads to an increase in capacity p of one traffic lane of the street or road due to reduction of braking distance s length; _ longitudinal slope i. let us consider how the capacity p will be changing fig.1 dependence of capacity p from speed v fig. 2 dependence of capacity p from coefficient of road adhesion φ   r 2 3600×16,67 p = = 1248 16,67 ×1,2 5 +16,67×1+ + 2,5 2× 9,81 0,7 +0,011 (pc/h/l) (3) fv=0,01[1+0,01(60-50)]=0,011 speed v. let us consider how the capacity p will be changing with speed v in the range from 10 up to 100 km/h. the maximum value of capacity obtained at speed v=30 km/h – p=1376 pc/h, the minimum one – at v=10 km/h – p=914 pc/h (fig. 1). when the speed exceeds 30 km/h, the capacity begins declining gradually due to a rapid rise of the braking distance s length, in the numerator of which formula the speed is squared; fig.1. dependence of capacity p from speed v coefficient of road adhesion φ. let us consider how the capacity p will be changing when the ratio of the coefficient of road adhesion φ will be in the range from 0.05 up to 0.95. the maximum value is obtained when φ=0.95 – p=1434 pc/h for dry crushed stone pavement processed by organic binders, the minimum – at φ=0.05 – p=198 pc/h for pavement covered with ice (fig. 2). the capacity increases, when road surface is dry and rough (respectively value of coefficient of road adhesion φ rises) and decreases, when it is wet and smooth (values of the coefficient are smaller, since on the surface of a street or a road a film from dust and water is formed, that worsens gripping of wheels of the car to the roadway surface); fig. 2. dependence of capacity p from coefficient of road adhesion φ rolling resistance coefficient f. let us consider how the capacity p will be changing when rolling resistance coefficient f will be in the range from 0.005 up to 0.3. the maximum value is obtained when f=0.3 – p=1476 pc/h, the minimum – at f=0.005 – p=1244 pc/h (fig. 3).   r 2 3600×16,67 p = = 1248 16,67 ×1,2 5 +16,67×1+ + 2,5 2× 9,81 0,7 +0,011 (pc/h/l) (3) fv=0,01[1+0,01(60-50)]=0,011 speed v. let us consider how the capacity p will be changing with speed v in the range from 10 up to 100 km/h. the maximum value of capacity obtained at speed v=30 km/h – p=1376 pc/h, the minimum one – at v=10 km/h – p=914 pc/h (fig. 1). when the speed exceeds 30 km/h, the capacity begins declining gradually due to a rapid rise of the braking distance s length, in the numerator of which formula the speed is squared; fig.1. dependence of capacity p from speed v coefficient of road adhesion φ. let us consider how the capacity p will be changing when the ratio of the coefficient of road adhesion φ will be in the range from 0.05 up to 0.95. the maximum value is obtained when φ=0.95 – p=1434 pc/h for dry crushed stone pavement processed by organic binders, the minimum – at φ=0.05 – p=198 pc/h for pavement covered with ice (fig. 2). the capacity increases, when road surface is dry and rough (respectively value of coefficient of road adhesion φ rises) and decreases, when it is wet and smooth (values of the coefficient are smaller, since on the surface of a street or a road a film from dust and water is formed, that worsens gripping of wheels of the car to the roadway surface); fig. 2. dependence of capacity p from coefficient of road adhesion φ rolling resistance coefficient f. let us consider how the capacity p will be changing when rolling resistance coefficient f will be in the range from 0.005 up to 0.3. the maximum value is obtained when f=0.3 – p=1476 pc/h, the minimum – at f=0.005 – p=1244 pc/h (fig. 3). as well as in the case of the coefficient of road adhesion φ, increasing of the rolling resistance coefficient f leads to an increase in capacity p of one traffic lane of the street or road due to reduction of braking distance s length; longitudinal slope i. let us consider how the capacity p will be changing when longitudinal slope i will be in the range from 0 up to 60‰. the longitudinal slope has an essential influence on the value of capacity p, the maximum value of which is obtained when a slope will be 60 ‰ on the rise – p=1299 pc/h, and the minimum value – when 60 ‰ slope – p=1194 pc/h (fig. 4). so, on the rise, when the value i is taken with the sign "+", the capacity increases due to shortening of braking distance s. and conversely, on the slope, when the value i is taken into account with the sign "", the capacity decreases. fig. 3. dependence of capacity p from rolling resistance coefficient f fig. 4. dependence of capacity p from longitudinal slope coefficient i the influence of driver’s psychological features in the formulae for calculation of capacity is taken into account by special coefficients and individual members: driver’s perception-reaction time t′. let us consider how the capacity p will be changing when driver’s perception-reaction time t′ will be in the range from 0.5 up to 2 sec. the maximum value of capacity p is obtained when t′=0.5 sec. – p=1510 pc/h, and the minimum, when t′=2 sec. – p=927 pc/h (fig. 5). when the driver’s perception-reaction time increases, the value of capacity p is reduced through the increase of the distance length, for which the rear vehicle moves, from the moment of awareness of the need to braking and according to the safe distance l. as well as in the case of the coefficient of road adhesion φ, increasing of the rolling resistance coefficient f leads to an increase in capacity p of one traffic lane of the street or road due to reduction of braking distance s length; longitudinal slope i. let us consider how the capacity p will be changing when longitudinal slope i will be in the range from 0 up to 60‰. the longitudinal slope has an essential influence on the value of capacity p, the maximum value of which is obtained when a slope will be 60 ‰ on the rise – p=1299 pc/h, and the minimum value – when 60 ‰ slope – p=1194 pc/h (fig. 4). so, on the rise, when the value i is taken with the sign "+", the capacity increases due to shortening of braking distance s. and conversely, on the slope, when the value i is taken into account with the sign "", the capacity decreases. fig. 3. dependence of capacity p from rolling resistance coefficient f fig. 4. dependence of capacity p from longitudinal slope coefficient i the influence of driver’s psychological features in the formulae for calculation of capacity is taken into account by special coefficients and individual members: driver’s perception-reaction time t′. let us consider how the capacity p will be changing when driver’s perception-reaction time t′ will be in the range from 0.5 up to 2 sec. the maximum value of capacity p is obtained when t′=0.5 sec. – p=1510 pc/h, and the minimum, when t′=2 sec. – p=927 pc/h (fig. 5). when the driver’s perception-reaction time increases, the value of capacity p is reduced through the increase of the distance length, for which the rear vehicle moves, from the moment of awareness of the need to braking and according to the safe distance l. fig. 3 dependence of capacity p from rolling resistance coefficient f fig. 4 dependence of capacity p from longitudinal slope coefficient i 17 journal of sustainable architecture and civil engineering 2015/2/11 when longitudinal slope i will be in the range from 0 up to 60‰. the longitudinal slope has an essential influence on the value of capacity p, the maximum value of which is obtained when a slope will be 60 ‰ on the rise – p=1299 pc/h, and the minimum value – when 60 ‰ slope – p=1194 pc/h (fig. 4). so, on the rise, when the value i is taken with the sign “+”, the capacity increases due to shortening of braking distance s. and conversely, on the slope, when the value i is taken into account with the sign “-”, the capacity decreases. the influence of driver’s psychological features in the formulae for calculation of capacity is taken into account by special coefficients and individual members: _ driver’s perception-reaction time t´. let us consider how the capacity p will be changing when driver’s perception-reaction time t´ will be in the range from 0.5 up to 2 sec. the maximum value of capacity p results and discussion the driver’s perception-reaction time has been a subject of investigations of many scientists. as e. lobanov (1980) established, the driver’s response time varies in different conditions – on the roads with two traffic lanes from 0.4 up to 2.3 sec. and on highways with a distribution zone from 0.5 up to 2.5 sec. further study and taking into account of drivers’ mental and physical qualities will lead to decrease in response time t' and, consequently, increase of the capacity p; clearance l2 . let us consider how the capacity p will be changing when reserve safety segment l2 will be in the range from 1 up to 10 m. the maximum value of capacity p is obtained when l2=1 m – p=1289 pc/h, the minimum, when l2=10 m – p=1080 pc/h. (fig. 6). when the clearance l2 length increases, the value of capacity p is reduced through the increase of the safety distance value of the vehicle. for each driver depending on his individual characteristics and qualifications (unless he moves in a column, when all drivers have to go with the common speed of the flow) there is an optimal safety segment, respecting which he confidently drives a car, responding to changing of road conditions in due time (babkov 1993). fig. 5. dependence of capacity p from driver’s perception-reaction time t′ fig. 6. dependence of capacity p from clearance l2 results and discussion the obtained values of capacity p are compared with the reference theoretical capacity рr. in order to determine the degree of influence of each of the factors mentioned above, one shall choose the maximum and minimum values of capacity p from the calculated by each of them and write data in table 1, 2. the driver’s perception-reaction time has been a subject of investigations of many scientists. as e. lobanov (1980) established, the driver’s response time varies in different conditions – on the roads with two traffic lanes from 0.4 up to 2.3 sec. and on highways with a distribution zone from 0.5 up to 2.5 sec. further study and taking into account of drivers’ mental and physical qualities will lead to decrease in response time t' and, consequently, increase of the capacity p; clearance l2 . let us consider how the capacity p will be changing when reserve safety segment l2 will be in the range from 1 up to 10 m. the maximum value of capacity p is obtained when l2=1 m – p=1289 pc/h, the minimum, when l2=10 m – p=1080 pc/h. (fig. 6). when the clearance l2 length increases, the value of capacity p is reduced through the increase of the safety distance value of the vehicle. for each driver depending on his individual characteristics and qualifications (unless he moves in a column, when all drivers have to go with the common speed of the flow) there is an optimal safety segment, respecting which he confidently drives a car, responding to changing of road conditions in due time (babkov 1993). fig. 5. dependence of capacity p from driver’s perception-reaction time t′ fig. 6. dependence of capacity p from clearance l2 results and discussion the obtained values of capacity p are compared with the reference theoretical capacity рr. in order to determine the degree of influence of each of the factors mentioned above, one shall choose the maximum and minimum values of capacity p from the calculated by each of them and write data in table 1, 2. fig. 5 dependence of capacity p from driver’s perceptionreaction time t´ fig. 6 dependence of capacity p from clearance l 2 is obtained when t´=0.5 sec. – p=1510 pc/h, and the minimum, when t´=2 sec. – p=927 pc/h (fig. 5). when the driver’s perception-reaction time increases, the value of capacity p is reduced through the increase of the distance length, for which the rear vehicle moves, from the moment of awareness of the need to braking and according to the safe distance l. the driver’s perception-reaction time has been a subject of investigations of many scientists. as e. lobanov (1980) established, the driver’s response time varies in different conditions – on the roads with two traffic lanes from 0.4 up to 2.3 sec. and on highways with a distribution zone from 0.5 up to 2.5 sec. further study and taking into account of drivers’ mental and physical qualities will lead to decrease in response time t´ and, consequently, increase of the capacity p; _ clearance l 2 . let us consider how the capacity p will be changing when reserve safety segment l 2 will be in the range from 1 up to 10 m. the maximum value of capacity p is obtained when l 2 =1 m – p=1289 pc/h, the minimum, when l 2 =10 m – p=1080 pc/h. (fig. 6). when the clearance l 2 length increases, the value of capacity p is reduced through the increase of the safety distance value of the vehicle. for each driver depending on his individual characteristics and qualifications (unless he moves in a column, when all drivers have to go with the common speed of the flow) there is an optimal safety segment, respecting which he confidently drives a car, responding to changing of road conditions in due time (babkov 1993). the obtained values of capacity p are compared with the reference theoretical capacity р r . in order to determine the degree of influence of each of the factors mentioned above, one shall choose the maximum and minimum values of capacity p from the calculated by each of them and write data in table 1, 2. journal of sustainable architecture and civil engineering 2015/2/11 18 excess of capacity p relative to the reference theoretical carrying capacity р r is calculated and it is determined for how many % p may increase or decrease depending on changes of the values of the speed v, the longitudinal slope i, the coefficient of road adhesion φ, the coefficient of rolling resistance f, the driver’s perception-reaction time t’, the clearance l 2 . proceeding from tables 1, 2 the diagrams are plotted (fig. 7, 8). as the diagrams show, the most influence on the value of capacity p has the coefficient of road adhesion φ and driver’s perception-reaction time t’. the adhesion (or friction) between vehicles tyres and road surface (represented in the safe distance formula 2 by the coefficient of road adhesion φ) is very important for traffic safety and helps to perform not only the essential braking in case of emergency and under normal circumstances, but also the motion of a vehicle itself. every driver tries to reach the certain safety level and adapts his betable 1 degree of influence of road-traffic conditions factors reference theoretical capacity р r , pc/h the maximum (minimum) capacity p by factor, pc/h excess, pc/h degree of influence max (min), % average value of degree of influence, % speed v 1248 1376 (914) 128 (334) 20 (23) 21.5 coefficient of road adhesion φ 1248 1434 (198) 186 (1050) 28 (73) 50.5 rolling resistance coefficient f 1248 1476 (1244) 288 (4) 44 (0.3) 22.15 longitudinal slope і 1248 1299 (1194) 51 (54) 8 (3.7) 5.85 factors reference theoretical capacity р r , pc/h the maximum (minimum) capacity p by factor, pc/h excess, pc/h degree of influence, max (min), % average value of degree of influence, % driver’s perceptionreaction time t´ 1248 1510 (927) 262 (321) 86 (66) 76 clearance l 2 1248 1289 (1080) 41 (168) 14 (34) 24 table 2 degree of influence of driver’s psychological features fig. 7 degree of influence of speed of motion v, longitudinal slope i, coefficient of road adhesion φ, rolling resistance coefficient f on the capacity p fig. 8 degree of influence of driver’s perceptionreaction time t’ and clearance l 2 on the capacity p fig. 7. degree of influence of speed of motion v, longitudinal slope i, coefficient of road adhesion φ, rolling resistance coefficient f on the capacity p fig. 8. degree of influence of driver’s perception-reaction time t' and clearance l2 on the capacity p improvement of road surface materials and materials of automobile tyres can provide better friction conditions and safer travels. while driving a car, the driver uses visual, auditory and kinaesthetic information. but how different drivers will behave at the same situation on the road? this is the most difficult question to answer in transportation studies. there are two approaches in driver’s behaviour research: concentrated on the study of driver’s stimuli or driver’s reactions. in the first approach the effect of certain pre-selected stimuli is determined on the behaviour of the driver, the second releases stimuli that cause a reaction (drew 1968). driver’s reaction approach is represented in formula 2 as perception-reaction time t'. one of the first studies says “we drive as we live” (tillmann et al. 1949), expressing that character and style of behaviour are reflected in our way of driving. but not only this, also gender, age, psychological and health conditions. the most promising way for decrease of perception-reaction time (and, of course, increase of capacity due to smaller safety gaps) lies in implementation of autonomous cars. this is a fast developing technology, which exists now in the form of prototypes and demonstration systems. conclusions for the assessment of factors influence on free flow capacity the estimation method was used, which is based on fundamental relationship between volume-speed-density and on safe-distance car-following model (pipes-forbes model). this method was chosen because of possibility to assess the number of fig. 7. degree of influence of speed of motion v, longitudinal slope i, coefficient of road adhesion φ, rolling resistance coefficient f on the capacity p fig. 8. degree of influence of driver’s perception-reaction time t' and clearance l2 on the capacity p improvement of road surface materials and materials of automobile tyres can provide better friction conditions and safer travels. while driving a car, the driver uses visual, auditory and kinaesthetic information. but how different drivers will behave at the same situation on the road? this is the most difficult question to answer in transportation studies. there are two approaches in driver’s behaviour research: concentrated on the study of driver’s stimuli or driver’s reactions. in the first approach the effect of certain pre-selected stimuli is determined on the behaviour of the driver, the second releases stimuli that cause a reaction (drew 1968). driver’s reaction approach is represented in formula 2 as perception-reaction time t'. one of the first studies says “we drive as we live” (tillmann et al. 1949), expressing that character and style of behaviour are reflected in our way of driving. but not only this, also gender, age, psychological and health conditions. the most promising way for decrease of perception-reaction time (and, of course, increase of capacity due to smaller safety gaps) lies in implementation of autonomous cars. this is a fast developing technology, which exists now in the form of prototypes and demonstration systems. conclusions for the assessment of factors influence on free flow capacity the estimation method was used, which is based on fundamental relationship between volume-speed-density and on safe-distance car-following model (pipes-forbes model). this method was chosen because of possibility to assess the number of 19 journal of sustainable architecture and civil engineering 2015/2/11 haviour according to the perception of changing friction conditions of road surface (its state of repair, roughness and whether it is wet or not) (wallman et al. 2001). improvement of road surface materials and materials of automobile tyres can provide better friction conditions and safer travels. while driving a car, the driver uses visual, auditory and kinaesthetic information. but how different drivers will behave at the same situation on the road? this is the most difficult question to answer in transportation studies. there are two approaches in driver’s behaviour research: concentrated on the study of driver’s stimuli or driver’s reactions. in the first approach the effect of certain pre-selected stimuli is determined on the behaviour of the driver, the second releases stimuli that cause a reaction (drew 1968). driver’s reaction approach is represented in formula 2 as perception-reaction time t’. one of the first studies says “we drive as we live” (tillmann et al. 1949), expressing that character and style of behaviour are reflected in our way of driving. but not only this, also gender, age, psychological and health conditions. the most promising way for decrease of perception-reaction time (and, of course, increase of capacity due to smaller safety gaps) lies in implementation of autonomous cars. this is a fast developing technology, which exists now in the form of prototypes and demonstration systems. for the assessment of factors influence on free flow capacity the estimation method was used, which is based on fundamental relationship between volume-speed-density and on safe-distance car-following model (pipes-forbes model). this method was chosen because of possibility to assess the number of factors presented in its formulae. they were grouped in two categories, which consider: 1 road-traffic conditions (speed v, longitudinal slope i, coefficient of road adhesion φ, coeffi-cient of rolling resistance f); 2 driver’s psychological features (driver’s perception-reaction time t’, clearance l2). it was found that in first group the biggest influence on free flow capacity has the coefficient of road adhesion φ (50.5%), in second – driver’s perception-reaction time t’ (76%). the result shows that the studies for improvement of traffic conditions on city road network should go in the direction of change for the better of these two factors, which will lead to safer motion and increase of capacity. the pipes-forbes model, which is used for this study, is still applied in corsim, vissim, paramics and integration traffic simulation software for description of steady-state behaviour of the flow. as it states that flow speed remains the same for different traffic volumes, its modified versions are included along with non-steady-state components. conclusions referencesdrew d. r. traffic flow theory and control. new york: mcgraw hill company; 1968. elefteriadou l., hall f., brilon w., roess r., romana m. revisiting the definition and measurement of capacity. 5th international symposium on highway capacity and quality of service, 2006. elefteriadou l., lertworawanich p. defining, measuring and estimating freeway capacity. washington: transportation research board meeting; 2003. forbes t. w., zagorski h. j., holshouser e. l., 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washington: national research council; 2000. wallman c.-g., åström h. friction measurement methods and the correlation between road friction and traffic safety. linköping: swedish national road and transport research institute; 2001. бабков в. ф. дорожные условия и безопасность движения [babkov v. f. road conditions and traffic safety]. москва: транспорт; 1993. дубровин е. н., ланцберг, ю. с. изыскания и проектирование городских дорог [dubrovin e. n., lantsberg yu. s. research and design of urban roads]. москва: транспорт; 1981. коноплянко в. и. организация и безопасность дорожного движения [konoplyanko v. i. traffic management and safety]. москва: транспорт; 1991. лобанов е. м. проектирование дорог и организация движения с учетом психофизиологии водителя [lobanov e. m. road design and traffic management with taking into consideration the psychophysiology of the driver]. москва: транспорт; 1980. містобудування. планування і забудова міських і сільських поселень: дбн 360-92** (державні будівельні норми україни) [city planning. planning and development of urban and rural settlements: dbn 360-92 ** (state construction standard of ukraine)]. київ: держбуд україни; 2002. самойлов д. с., юдин в. а., рушевский, п. в. организация и безопасность городского движения [samoilov d. s., yudin v. a., rushevsky p. v. management and safety of urban traffic]. 2-е изд. москва: высшая школа; 1981. споруди транспорту. автомобільні дороги: дбн в.2.3-4:2007 (державні будівельні норми україни) [transport facilities. highways: dbn v.2.34:2007 (state construction standard of ukraine)]. київ: мінрегіонбуд україни, 2007. споруди транспорту. вулиці та дороги населених пунктів: дбн в.2.3-5-2001 (державні будівельні норми україни) [transport facilities. streets and roads of settlements: dbn v. 2.3-52001 (state construction standard of ukraine)]. київ: держбуд україни, 2001. about the author maryna öztürker lecturer lutsk national technical university, faculty of construction and design, department of municipal engineering and construction main research area road networks design, theory of traffic flow, traffic management and control address artseulov st. 9/32, 43021 lutsk, ukraine tel. +380 95 7506981 e-mail: maryna.ozturker@gmail.com 5 journal of sustainable architecture and civil engineering 2016/2/15 *corresponding author: fkakande225@googlemail.com retrofitting and greening existing buildings: strategies for energy conservation, resource management and sustainability of the built environment in nigeria received 2016/07/11 accepted after revision 2016/09/01 journal of sustainable architecture and civil engineering vol. 2 / no. 15 / 2016 pp. 5-12 doi 10.5755/j01.sace.15.2.15557 © kaunas university of technology retrofitting and greening existing buildings: strategies for energy conservation, resource management and sustainability of the built environment in nigeria jsace 2/15 http://dx.doi.org/10.5755/j01.sace.15.2.15557 introduction oluwafemi k. akande* and remi e. olagunju federal university of technology, department of architecture, pmb 65, minna, nigeria energy consumption in residential buildings is one of the increasing phenomenal in the built environment. it has become imperative to react to the state of rapidly dwindling natural resources, environmental pressures and climate change posing fundamental threat to economic systems and human survival in nigeria and globally. until fairly recently, green considerations for existing residential buildings have received less attention. in nigeria, thousands of households of low income buildings spends large sums of their earnings on energy bills, while getting less energy-driven services for their appliances and utilities to meet their needs. this paper explores possible alternatives for less dependence on national energy supply with more environmental benefits through sustainable retrofit and resource-efficiency interventions for low-income houses. the objective is to address issues relating to energy generation, conservation and other associated resource management with a view to achieving the development of a low carbon and more eco-friendly built environment. it is expected that the outcome of this paper will make an important contribution in the form of recommendations for future policies and programmes regarding retrofitting of existing residential houses and the construction of new ones in nigeria. it concludes that if policies and regulatory mechanism are put in place for greening low-income housing in nigeria, this could deliver a pathway to improving energy efficiency of the existing building sector. keywords: energy conservation, low income houses, retrofitting, greening, sustainability. globally, it is acknowledged that there is need to devote much attention to how buildings are designed and constructed to reduce their energy consumption. a major issue arising from the concern about climate change is the reduction of energy use in residential buildings. presently, it is estimated that nearly half of million tonnes of co2 emissions each year is attributed to energy use by residential buildings. given that globally by 2050, the number of households is projected to increase by 67 percent, this make the residential sector a significant area that requires more attention. however, while the reductions in greenhouse gas emissions from residential sector is considered critically important; efforts geared towards achieving this is still inadequate to meet the required level of reductions predicted by climate change experts to prevent catastrophic clijournal of sustainable architecture and civil engineering 2016/2/15 6 mate change. this brings to fore the need for greater attention to be accorded to existing building stock most especially residential buildings. in the 2030 challenge, the american institute of architects (aia) along with u.s. green building council advocated that new construction of residential and commercial buildings should use half the fossil fuel of average existing buildings and a gradual increase in performance of the existing buildings so that by 2030 new buildings are carbon-neutral. meanwhile, achieving the gradual increase in energy performance of existing residential buildings would require leading-edge energy retrofits. presently, in nigeria several thousands of housing units for the low income group are designed and constructed with little or no regard for low energy use and other ‘green’ design considerations. thus, high levels of additional energy are required to keep the houses cool in the hot season months. in nigeria, the energy inefficiency of the existing housing stock result to the demand for more energy to reach comfortable temperatures. most times, the required indoor comfort levels cannot be reached without considerable expenditure on energy. hence, nigeria is faced with the reality that requires retrofitting and greening strategies for vast majority of existing houses that provides less adequate internal comfort to reduce their environment burden. this paper aims is to explore the avenues for potential retrofit in nigeria existing residential buildings. the specific objectives include; (i) to identify areas where retrofits measures can be applied to low income houses with a view to reducing their energy consumption through major renovations; (2) to identity the green features that can be retrofitted into existing residential buildings for efficient energy utilization and conservation; and (3) to highlight the challenges several dividends accruable from green buildings. aim and objectives theoretical framework methodological approach the methodology is based on secondary data collection approach which includes a comprehensive assessment and analysis of scientific literature from google scholar, science direct scopus and web of science. relevant materials were consulted from refereed journal articles, government reports, books, theses and research reports to achieve the purpose of the paper. other methods include literature search with the aid of the use of keywords altered according to the database searched. in general, the major keywords searched revolved around: (1) some policy instruments on greening of low income housing; (2) analytical framework towards selecting, evaluating and examining best practice case studies of greening low income housing projects; and (3) examining different promising areas. in addition, some bibliographies were reviewed using scopus, web of science, and google scholar for possible additional materials relevant to the topic. consequently, the paper is organized as follows: concept of green retrofits are presented along with examples of global efforts in retrofits of existing buildings. this is followed by energy conservation and management strategies suitable to promote greening existing buildings. implementation challenges associated to retrofitting for energy savings in existing low income houses are evaluated. finally, recommendations and suggestions are proffered for possible realisations of energy conservation and management for sustainability of low-income houses. the concept of green retrofits and global efforts on existing buildings green retrofits involve the upgrade of an existing building either wholly or partially occupied to improve energy and environmental performance, reduce water use, and improve the comfort and quality of the space in terms of natural light, air quality, and noise. it can be equally simple as putting in new heating, ventilating, and air-cooling parts, mounting solar panels on a ceiling. according ma et al. (2012) greening existing buildings is one of the primary approaches to 7 journal of sustainable architecture and civil engineering 2016/2/15 achieving sustainability in the built environment at relatively low cost and high consumption rates. although there is a broad range of retrofit technologies readily available, methods to identify the most cost-effective retrofit measures for special projects is still a major technological challenge. across the world, several attempts have been made in developed countries like the us, australia and uk towards improving energy efficiency of existing buildings. these attempts include approaches such as provision of policy guidance, financial and technical support to implement energy efficiency measures. likewise, a substantial number of works by numerous authors (asadi et al., 2012; flourentzou and roulet, 2002; goli et al., 2011) have been carried out to explore energy efficiency through diverse avenues directed for improved performance in energy use of existing residential houses. cohen et al. (1991) investigated saving energy and efficiency in cost retrofit options of individual single family buildings and analysed metered energy consumption with the real cost of installation. the author’s findings indicated that insulating ceilings and walls are cost effective retrofit and window replacement a feasible retrofit option but has a result of smaller normalised annual energy saving (of between 2–5 percent. gorgolewski (1995) produced a method to optimise renovation strategies for housing retrofit by adopting a life cycle cost approach to evaluate and compare performance of different retrofit measures. the outcomes indicated that the paybacks are higher than the entire retrofit measures. goldman et al. (1998) reported findings from their studies on the retrofit of us multifamily buildings. the authors’ results were based on analysing data that were measured and obtained from a record of different apartments. it was found that it cost much less to retrofit a fuel-heat buildings when compared to electric-heat buildings with the payback periods for the two buildings indicating six (6) and twenty to twenty five (20–25) years respectively. al-ragom (2003) examined residential buildings retrofit in hot and arid climates the study revealed that significant energy reduction is achievable if the cost of implementing the retrofit cost was supported fully by the government. alanne (2004) performed an analysis of a finnish apartment and tested the applicability and functionality of a multi-criteria ‘knapsack’ model proposed by the author. the model was developed to aid in the selection of the most viable renovation actions in the conceptual phase of a renovation project. mahlia et al. (2005) used annualised costs and cash flow in calculating the economic impact of lighting retrofits in residential sector in malaysia. the authors presented the cost–benefit analysis and emission reduction of lighting retrofits. their findings indicated that in the retrofit of efficient lighting systems, cost–benefit was a determinant factor for saving energy. a different method undertaken by zavadskas et al. (2008) was adopted to know the effectiveness of retrofitting houses on the basis of expected energy savings and increase in the worth of refurbished buildings in the market. the study found that choosing retrofit situations depends on strategic urban development programmes, renovation cost, heating energy saving and expected increment of market value. dodoo et al. (2010) evaluated the implication of primary energy through life cycle assessment in the retrofit of a four-storey apartment building to the standard of a passive house. the results showed that reduction in final energy use was achieved, although the primary energy is still determined by the type of energy supply system used. bin and parker (2012) observed the environmental performance of a century home and compared its original and after retrofit environmental footprint. the findings indicated through renovation, energy performance of existing buildings’ can be enhanced and be made environmentally sustainable sound. additionally, research on existing non-residential buildings by several other scholars such as hestnes and kofoed, (2002); chidiac et al. (2011); and ardente et al. (2011) showed significant reduction in the use of energy from existing buildings is achievable through appropriate retrofit or renovation defined by flourentzou and roulet (2002) as the work that require upgrading an existing old building. journal of sustainable architecture and civil engineering 2016/2/15 8 in africa, a few demonstrated pilot projects carried out in south africa shows both economic and societal benefits of more sustainable design in low-income housing. the greening interventions into existing houses were not only found to translate into energy savings, but also resulted in water and financial savings and reduced associated illness, safety risks, greenhouse gas emissions and environmental impact. similarly, it was also noted that job creation also became a crucial component in the successful delivery of the projects. thus, according to ma et al., (2012) retrofit or refurbishing of the building constitutes a type among several methods to achieve a reduction in energy use and the consequent greenhouse gas emissions from buildings. based on the foregoing, while it is can be seen that there is a global drive for improving the existing building stock yet the available literature indicated that there is less drive and attention paid to improving the environmental performance of existing low cost houses in nigeria. this is in spite of building retrofit technologies available to maximise energy savings. thus, this paper has identified and posits the need to find retrofit solutions to reduce energy consumption and rising carbon footprint in existing residential buildings. energy conservation and management strategies for greening existing buildings in recent years, there has been an increasing effort in the building industry to develop and apply different retrofit strategies and management tools to ensure improved performance in existing building energy consumption. the current state of the art of the strategies employed to date according to ma et al. (2012) is categorised into three, namely: supply and demand side management, and change in energy use patterns (i.e. human energy use behavioural factors). supply side management the strategies for building retrofit through supply side management comprise of electrical systems, and the use of renewable energy (e.g. solar hot water, solar photovoltaics (pv), wind energy, geothermal energy, etc.) as alternative energy supply systems to provide electricity and/or thermal energy for buildings (ma et al., 2012). recently, there has been an increase in the attention given to the use of renewable energy technologies as one of the building retrofit strategy due to the greater impact of environmental damage. the application of renewable energy technologies in retrofitting millions of houses in nigeria will be more beneficial to several households. this is as a consequence of a cost increase in electricity tariffs with energy consumption charged per kilowatt hour without a noteworthy improvement in electricity generation, transmission, and distribution in the state. the nigerian electricity regulatory commission (nerc) has estimated that about 60% of electric power customers fall within the r2 band (i.e. a consumer who uses his premises as a residence – house) with r2 as one of the categories of residential electric power consumers. demand side management ma et al., (2012) points out that retrofit through demand side management is made up of reduction in cooling and heating demand strategies along with the usage of energy efficient equipment and low energy technologies. the demand for cooling and heating a building can be minimised through building fabric retrofitting and the application of other strategies such as air tightness, windows shading, etc. other low energy strategies applicable to building retrofit projects include natural ventilation, advance control schemes, etc. ma et al., (2012) noted that retrofitting building fabric, building services systems and metering systems will require a reduced cost in investment with considerable environmental benefits when compared with other retrofit interventions such as renewable energy technologies. discussion 9 journal of sustainable architecture and civil engineering 2016/2/15 change in occupant’s energy consumption pattern this is the biggest and the most significant strategies for energy conservation and management in low income houses. it requires proper orientation of the building users on their consumption pattern and closely working early and frequently with occupants in the process of retrofitting. this would enhance the occupants’ understanding of energy management required at different times of the year through behavioural and system controls. implementation challenges of retrofitting for energy savings in existing houses to execute retrofitting projects and achieving improvements to existing low income houses means having to deal with some challenges. for instance, in nigeria, the estimated number of existing housing units is about 10.7 million (pison housing company, 2010) putting the existing housing stock at 23 per 1,000 inhabitants (makinde, 2014) and of these, about 88% are self-built with evidence of poorly constructed and under maintained houses. the success of implementation will largely depend on the combination of readiness and involvement of the federal and state government, support from local authorities, and cooperation of the householders, appliance and energy supply industries. this implies that active stakeholder engagement would be necessary throughout the implementation project and particularly with the community of local residents. other anticipated implementation challenges include the technical aspects of retrofitting projects in the following areas: insulated ceilings in tropical and sub-tropical climates, insulated ceilings tend to trap heat built up during the day, unless there is effective ventilation and sufficient levels of insulation or heat moderation (through methods that keep summer radiant heat out). different technologies may be more applicable or appropriate due to difference of climatic zones. for instance, solar water heaters (swhs) could be the most appropriate intervention in a particular zone while insulated ceilings could be the most applicable in others. electrical rewiring in most cases the occupants of several low-cost houses are not the only electricity users connected to a household meter. it’s not unlikely that one or more other informal house shares the same electricity source as a particular tenant might be giving electricity to extended family members or selling it to a neighbouring non-electrified tenant’s house. meanwhile, the number of occupants on these properties can vary significantly, which could affect any retrofit measure on metered data. thus, electrical rewiring of the entire building may be required in such retrofit where many illegal and non-compliant electrical installations to safety standards exist. absence of rainwater harvesting mechanism in nigeria, most houses are not designed with guttering or built in such a way to make gutter retrofits simple for rainwater harvesting purposes. hence, innovative guttering systems would need to be devised as part of retrofitting strategies. however, installing guttering systems to existing houses could become challenging, especially where the houses are not designed with external timber rafters, purlins or trusses to which gutter brackets could be attached. this could result in having functionality problems and may not last as long as conventional gutter systems. poor quality roofing poor quality roofing can become a significant hazard to workers installing swhs and can impact the potential success of the swh installation. where roof structures are weak, installation of journal of sustainable architecture and civil engineering 2016/2/15 10 swhs becomes a challenge as great care needs to be taken to prevent further damage and workers falling through the roof which poses a danger to both people and the property. furthermore, roof leaks will require some repair before insulated ceilings can be installed. hence, the budget would need to be set aside for repair of leaks or replacement of roof members. recommendations for green retrofitting of existing residential buildings in nigeria nigeria’s existing housing stock present energy efficiency problems that require urgent attention. this needs to be driven by increasing focus from the government and the private sector to find ways of helping households save money on their energy bills, decrease their emissions, and make their homes comfortable to live. to achieve this, the following should apply for effective green and sustainable retrofitting of existing residential buildings: _ existing energy and water systems should be examined and upgraded to ascertain that they function properly and enhance significant reduction in energy consumption. _ occupancy energy and water consumption patterns should be assessed and efficiency strategies introduced where necessary. _ as much as possible areas where natural ventilation and fresh air intake is required should be identified and introduced as replacements to reduce cooling loads. _ solar shading devices should be introduced for windows where practicable. _ installation of smart meters to monitor real-time electricity and water consumption, control demand and increase users behavioural energy use awareness should be introduced if the houses are not already metered. _ renewable energy installation options should be encouraged by the government to lessen the long term financial burden of purchasing fossil fuel-based energy. many domestic activities that take place in nigeria houses involve the constant use of hot water. this requires a substantial amount of energy use if the hot water kettle is used. and since most households cannot afford gas and electric cooker, the solar water heaters (swhs) and pipe reticulation systems could be installed to deliver hot water directly into the house. a 100-litre, low pressure, and evacuated tube-type systems with no electrical backup connection is recommended. the solar water heaters have superior performance qualities with the capacity to deliver balanced cold/hot pressure and ‘safe’ tempered water at 50 to 60 degrees celsius. _ in most existing low income houses, ceiling conditions are in deplorable conditions leading to excessive heat into the interior. retrofitted ceilings could make a marked difference to the internal comfort levels of the houses. in place of the present ceiling board in lower income houses, a 30mm thick isoboard (insulated ceiling board) having a thermal resistance value (called ‘r’ value) of 1 could be installed as a replacement for improvement in the interior thermal performance. _ a nationwide standard for electrical installation should be developed and their retrofitting coordinated by well-trained registered technicians. dangerous and exposed electrical wires that prevailed in many of the houses should be replaced to prevent excessive electricity consumption and to ensure safety. it is most likely that many electrical wires have exceeded lifetime. therefore, qualified electricians should be employed to conduct electrical inspections to produce the required compliance certification during the retrofit. _ a national residential lighting energy efficiency standard should be developed to mandate the replacement of incandescent bulbs within a stipulated period with compact fluorescent (cfl) bulbs in all residential buildings as they are more energy efficient. the cost of the bulb replacement nationwide should be highly subsidised by the government to encourage com11 journal of sustainable architecture and civil engineering 2016/2/15 conclusions pliance. dimmable switches should be introduced along with other lighting energy efficiency techniques such as the use of timers or sensors for electrical appliances. _ the low pressure solar heating system that delivers water at a low flow rate (less than ten litres per minute) should be installed to encourage water conservation and improve efficiency. existing inefficient water delivery services should be replaced with water efficient taps having aerators, sensors with designing flow rates. similarly, pvc pipes should be substituted with high density polyethylene (hdpe) pipes. this is considered to have better properties for water conservation through its properties such leak-free performance, better resilience and flexibility than pvc in terms of damage from digging and surges. additionally, existing old wc should be exchanged with low flush capacity wcs or be incorporated with a dual flush toilet with lesser litres of water per flush. on the alternative, extra space within the wc tank can be reduced using a lightweight block to minimise the quantity of water used. _ active stakeholder participation should be encouraged with adequate resources directed towards the process. collaboration with services providers such as electricity suppliers and involvement of the local community leaders through community briefing is essential to ensure the achievement and the smooth running of the project. this way, less literate residents would have time to get to grips with the project. to contribute to the global efforts in alleviating the challenges associated with climate change, nigerian government needs to explore and employ innovative approaches and tools to lessen its contributions to global co2 emissions. a synergistic relationship is needed between house owners, housing developers and housing industry take advantage of the opportunities of retrofitting of inefficient existing houses which hold huge prospect for reducing energy consumption. meanwhile, the use of policy to establish and mandate resource conservation and energy management in existing buildings would serve as an effective mechanism through which residential building retrofit can be successfully implemented. thus, the current proposed climate change policies in nigeria need to be reviewed to integrate minimum energy use standards for existing buildings. in the meantime, mandatory building codes as a form of regulatory mechanism have the potential to influence the retrofit of existing residential houses. thus, this regulatory mechanism to the extent that it exists and applied in nigeria can deliver a pathway to improving energy efficiency of the existing building sector. retrofitting operations supported by utilities and included in emissions reduction mechanisms are a decisive solution to the problems of energy expenditure and cost. referencesalanne, k. selection of renovation actions using multi-criteria knapsack model, automation in construction, 2004; 13: 377–391. http://dx.doi. org/10.1016/j.autcon.2003.12.004 al-ragom, f. retrofitting residential buildings in hot and arid climates, energy conversion and management, 2003. 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http://dx.doi.org/10.1016/j.energy.2011.05.050 cohen, s., goldman, c., harris, j. energy savings and economics of retrofitting single-family buildjournal of sustainable architecture and civil engineering 2016/2/15 12 about the authors ings, energy and buildings, 1991; 17: 297–311. http://dx.doi.org/10.1016/0378-7788(91)90012-r dodoo, a. gustavsson, l. sathre, r. life cycle primary energy implication of retrofitting a wood-framed apartment building to passive house standard, resources, conservation and recycling, 2010; 54: 1152–1160. http://dx.doi.org/10.1016/j.resconrec.2010.03.010 flourentzou, f., roulet, c.a. elaboration of retrofit scenarios, energy and buildings, 2002; 34: 185–192. http://dx.doi.org/10.1016/s0378-7788(01)00106-2 goldman, c.a., greely, k.m., harris, j.p. retrofit experience in u.s. multifamily buildings: energy savings, costs, and economics, energy, 1988; 13: 797–811. http://dx.doi.org/10.1016/0360-5442(88)90085-0 goli k., kosori, v., furundzi a.k. general model of solar water heating system integration in residential building refurbishment – potential energy savings and environmental impact, renewable and sustainable energy reviews, 2011; 15: 1533–1544. http://dx.doi.org/10.1016/j.rser.2010.11.052 gorgolewski, m. optimizing renovation strategies for energy conservation in housing, building and environment, 1995; 30: 583–589. http://dx.doi.org/10.1016/0360-1323(95)00011-t hens, h. energy efficient retrofit of an end of the row house: confronting predictions with long-term measurements, energy and buildings, 2010; 42: 1939–1947. http://dx.doi.org/10.1016/j.enbuild.2010.05.030 hestnes, a.g. kofoed, n.u. effective retrofitting scenarios for energy efficiency and comfort: results of the design and evaluation activities within the office project, building and environment, 2002; 37: 569–574. http://dx.doi.org/10.1016/s0360-1323(02)00003-3 ma, z.j., cooper, p., daly, d., ledo, l., existing building retrofits: methodology and state-of-theart. energy and buildings, 55; 2012: 889–902 http://dx.doi.org/10.1016/j.enbuild.2012.08.018 mahlia, t.m.i., said, m.f.m., masjuki, h.h., tamjis, m.r. cost-benefit analysis and emission reduction of lighting retrofits in residential sector, energy and buildings, 2005; 37: 573–578. http://dx.doi.org/10.1016/j.enbuild.2004.08.009 makinde, o. o. housing delivery system, need and demand. environ dev sustain, 2014; 16: 49–69. http://dx.doi.org/10.1007/s10668-013-9474-9 pison housing company. overview of the housing finance sector in nigeria. commissioned by ef in a and finmark, finmark trust, 2010; vol. 1: pp. 15–20). thomas, o., alan, m., lamberts, r. rating the energy performance of buildings. the international journal of low energy and sustainable buildings, 2004; 3: retrieved may 22, 2016, from the us department of energy’s energy citations database. zavadskas, e. raslanas, s. kaklauskas, a. the selection of effective retrofit scenarios for panel houses in urban neighborhoods based on expected energy savings and increase in market value: the vilnius case, energy and buildings, 2008; 40: 573–587. http://dx.doi.org/10.1016/j.enbuild.2007.04.015 phd. oluwafemi k. akande senior lecturer federal university of technology, department of architecture, pmb 65, minna, nigeria main research area building energy performance and environmental sustainability in architecture address department of architecture federal university of technology pmb 65, minna, nigeria tel. +2347061014886 e-mail: fkakande225@googlemail.com phd. remi e. olagunju associate professor federal university of technology, department of architecture, pmb 65, minna, nigeria main research area building maintenance address department of architecture federal university of technology pmb 65, minna, nigeria tel. +23470065003865 e-mail: rembenz@gmail.com 49 journal of sustainable architecture and civil engineering 2015/4/13 corresponding author: aydlswaidani@yahoo.fr production of more sustainable mortar using finer volcanic scoria-based blended cements received 2015/09/09 accepted after revision 2015/11/02 journal of sustainable architecture and civil engineering vol. 4 / no. 13 / 2015 pp. 49-61 doi 10.5755/j01.sace.13.4.13245 © kaunas university of technology production of more sustainable mortar using finer volcanic scoria-based blended cements jsace 4/13 http://dx.doi.org/10.5755/j01.sace.13.4.13245 introduction use of natural pozzolan is growing rapidly in the construction industry due to its economical, ecological and technical benefits. however, they are often associated with shortcomings such as the need to moist-curing for longer time and a reduction of strength at early ages. syria is relatively rich in volcanic scoria. the objective of the study is to investigate the effect of blain fineness of cement on the strength development of scoria-based cement mortars. in the study, mortar specimens have been produced with four types of cement: one plain portland cement (control) and three scoria-based blended cements with three replacement levels: 25, 30% and 35%, respectively. all blended cement types have been interground into four different blaine fineness: 2400, 3200, 4200 and 5100 cm2/g. the development of the compressive and flexural tensile strength of all mortar specimens with curing time has been investigated. the effects of the blaine fineness of the scoriabased blended cement on the compressive and flexural strengths of mortar have been evaluated at curing ages of 2, 7, 28 and 90 days, respectively. test results revealed that there is a decrease in strength with increasing amounts of scoria. in addition, there was found an increase in strength with increasing the blaine fineness values. good correlations between mechanical strengths and blaine fineness have also been observed at different curing times. further, based on the results obtained, an empirical equation was derived to predict the mechanical strengths of scoria-based cement mortars with curing times based on blaine fineness. effects of blaine fineness on some physical properties of blended cements have been reported, as well. keywords: mechanical strength, blaine fineness; blended cement; natural pozzolan; volcanic scoria. aref mohamad al-swaidani faculty of architectural engineering, arab international university (aiu), damascus, syria samira dib aliyan syrian arab organization for standardization and metrology (sasmo), damascus, syria nazeer adarnaly the general organization for cement & building materials (gocbm), damascus, syria use of pozzolans as substitute for portland cement is one of the most effective approaches in order to make the concrete industry more sustainable; each 1kg of substitution reduces by about 1 kg the emission of co2, and saves the energy required to produce 1 kg of cement. in addition, this use will lead to conservation of finite natural resources. further, pozzolans could be used to make stronger and more durable concretes (aitcin & mindess, 2011). natural pozzolan is one of the oldest construction materials. the roman empire is the most synonymous with the use of pozzolans, the name deriving from volcanic rock found near naples. (walker & pavia 2011). it is being widely used as cement replacement due to its ecological, economical and performance-related advantageous properties (kouloumbi et al. 1995; khan & alhozaimy 2010; journal of sustainable architecture and civil engineering 2015/4/13 50 moufti et al. 2000; al-chaar et al. 2013; senhadji et al. 2012). however, use of natural pozzolan causes longer setting times and lower early strengths compared with plain portland cement (shi 2001). strength of concrete is commonly considered its most valuable property. it is well-known that an increase in specific surface area of cement causes an increase in mechanical properties of mortars and concretes, especially at early ages. since hydration starts at the surface of the cement particles, it is the total surface area of cement that represents the material available for early hydration. thus the rate of hydration depends on the fineness of cement particles (neville 2011). to overcome the disadvantages of low early strengths of cements containing natural pozzolans, the prolonged grinding of blended cement could be therefore a solution. day and shi (1994), by studying the effect of grinding on the strength development of natural pozzolan from central america, concluded that a good linear relationship existed. they showed that an increase of 1.5 mpa can be expected for every 1000 cm2/g increase in fineness. their study included blaine fineness in the range of 2500 to 5500 cm2/g. on the contrary, rossi and farchielli (1976) in an earlier study did not find any proportionality between the surface area of pozzolans and reactivity with lime for a given material. syria has important volcanic areas. more than 30 000 km2 of the country is covered by tertiary and quaternary-age volcanic rocks (gegmr, 2011), among which scoria occupies important volume with estimated reserves of about three-quarters billion tonnes (gegmr 2007). however, their potential use in making concrete is not well established. the cement produced in the country is almost of cem i, although an addition of natural pozzolan up to 5% was frequently used in most local cement plants. hence, less than 300 000 tonnes of these pozzolans are only exploited annually (the annual production of portland cement in syria is about 6 million tonnes) (gocbm, 2012). this study is part of the first detailed research in syria to investigate the potential utilization of scoria as cement replacement in producing portland-pozzolan cements. in the study, in order to better understand the influence of blaine fineness on mechanical strength of scoria-based cement mortars, compressive and flexural strengths experimentally have been investigated using four blaine fineness values of 2400, 3200, 4200 and 5100 cm2/g, respectively. furthermore, relationships between blaine fineness and the development of mechanical strength of scoria-based cement mortars with different curing times have been analyzed in this paper. some physical properties of the studied blended cements have also been reported. the study is of particular importance not only for the country but also for other countries of similar geology, e.g. harrat al-shaam, a volcanic field covering a total area of some 45 000 km2, third of which is located in syria. the rest coves parts from jordan and saudi arabia. the basic premise of the study is that producing finer blended cements containing high levels of scoria may overcome the low early strength of such cement. further, such application would be of a great importance to both economy and ecology. an equation to estimate the mechanical strength of such kind of blended cement depending on the blaine fineness value and the scoria content has also been derived. scoria the volcanic scoria used in the experiments was quarried from dirat-at-tulul site, at about 70 km southeast of damascus as shown in (fig.1). the mineralogical analysis showed the scoria is mainly composed of amorphous glassy ground mass, vesicles, plagioclase and olivine with the following percentages (based on an optical estimate): 20%, 35%, 20% and 25%, respectively. thin sections of the investigated scoria are shown in (fig. 2). the chemical analysis of scoria used in the study is summarized in (table 1). materials and methods 51 journal of sustainable architecture and civil engineering 2015/4/13 cement samples four cement samples have been prepared; one plain portland cement cem i (control) and three cem ii/b-p samples with three replacement levels of 25, 30 and 35% (en 197-1). 5% of gypsum was added to all these binder samples. these replacement levels of scoria have been adopted because they fig.1 map of harrat al-shaam, photos of the studied site and the used scoria aggregate: a. map of the volcanic area “harrat al-shaam” and the studied site b. the studied scoria quarry, some volcanic scoria cones are shown behind. c. the studied scoria aggregate improved durability-related properties of concrete significantly (al-swaidani & aliyan, 2015). the clinker was obtained from adra cement plant, damascus, syria. all samples were interground by a laboratory grinding ball mill of 25 kg raw mix capacity into four blaine fineness values: 2400, 3200, 4200 and 5100 cm2/g. the intergrinding process has been adopted because it requires less energy than separate grinding, especially for the production of high fineness products (binici et al. 2007). the blaine fineness was measured using air permeability method in accordance with the european standard (en 196-6). the principle is to measure the resistance to air flow through a compact bed of cement powder. the chemical and physical properties of the cement samples produced for this study are shown in (table 1) and (table 2), respectively. cem i (the control sample) was designated as c1, whereas scoria-based cements were designated according to the replacement level. for instance, c2/25% and c4/35% refer to the blended cements containing 25% and 35% of scoria, respectively. cement mortars the mortar specimens of all cements used in the experiments were prepared using these cements and sand meeting the requirements of astm c778. the sand used is standard ottawa sand; bulk density=1.6 g/cm3, fineness modulus=2.1. in all mixtures, binder: sand ratio was kept constant as 1:2.75 by weight. mixture containing cem i was prepared with a w/b ratio of 0.485. mixtures containing scoria-based binder were prepared by changing the w/b ratio in order to obtain a flow within±5 of that of the cem i mortar. after being kept in a wet cabinet for 24 hours, the mortar specimens were demolded and kept in water at 20±2 oc until the time of testing. a b c fig. 2 thin sections of the scoria: a. microphenocryst of olivine in volcanic glass matrix with vesicles, some of which are filled with white minerals. b. microphenocrysts of elongated plagioclase in volcanic glass matrix with vesicles, some of which are filled with white minerals journal of sustainable architecture and civil engineering 2015/4/13 52 physical and mechanical properties water requirements, setting times and volume expansion of all cement paste specimens have been determined in accordance with en 196-3. six halved-specimens obtained from the three mortar specimens used in the flexural strength tests, were tested for the determination of compressive strength of mortars under the same laboratory conditions as those applied in the flexural strength test. the compressive and flexural strength development was determined on 40×40×160 mm prismatic specimens, in accordance with en 196-1, at ages of 2, 7, 28 and 90 days, respectively. the values reported in the results represent the average of six readings for compressive strength test and the average of three readings for all other tests. chemical composition (by mass, %) cementitious materials scoria* c1/cem i c2/25% c3/30% c4/35% sio2 46.52 20.69 24.00 24.33 24.61 al2o3 13.00 5.09 6.55 6.80 7.39 fe2o3 11.40 4.23 5.43 5.47 6.31 cao 10.10 60.62 50.30 48.00 44.84 mgo 9.11 2.46 3.87 4.11 4.63 so3 0.27 2.26 2.30 2.26 2.55 loss on ignition 2.58 1.41 1.47 1.48 1.60 na2o 2.14 0.60 1.07 1.16 1.31 k2o 0.77 0.35 0.50 0.53 0.57 cl<0.1 0.023 0.018 0.019 0.019 insoluble residue 3.22 1.03 3.48 4.08 5.33 pozzolan activity index [astm c 618] 79 (at 7 days) 85 (at 28 days) * sio2(reactive) = 42.22% (determined in accordance with en 196-2 ). table 1 chemical composition of volcanic scoria and cement types of 3200 cm2/g blaine fineness properteis of scoria and blended cements as seen from table 1, scoria is considered as suitable material for use as pozzolan. it satisfied the standards requirements for such a material by having a combined sio2, al2o3 and fe2o3 of more than 70%, a so3 content of less than 4% and a loss on ignition of less than 10% (astm c618). sio2reactive content is more than 25%, as well (en 197-1). in addition, it has a strength activity index with pc higher than the values specified in astm c618. the chemical properties of scoria-based blended cements are also in conformity with the standards requirements (astm c595). their contents of mgo and so3 are less than 6 and 4%, respectively. the loss on ignition is also less than 5% as specified in astm c595. physical propreties of cements used water requirements the results of water requirements are presented in (table 2). finer scoria-based blended cements have a greater water demand. the smaller the material particle size is the more water the material may absorb (due to the large surface area) (jaya et al., 2011). this agrees with the well-known fact of finer particles requiring a greater amount of water to produce a given workability (walker & pavia, 2011). however, as it can been seen from (table 2), there is no significant change in the water content even for the blended cement containing 35% of scoria content which increased only results and discussion 53 journal of sustainable architecture and civil engineering 2015/4/13 by less than 5% when compared to c1/cem i, for the same blaine fineness value. this could be explained by the lubricant effect of scoria on paste when finely divided (yetgin & cavdar, 2006). setting times knowledge of the setting characteristics of cement paste is rather important in the field of concrete construction. the setting behavior of a cement paste plays an important role in determining the time available for placement, consolidation, finishing, and form removal. table 2 illustrates the setting times of the control mortar and mortars containing scoria-based blended cements for all blaine fineness values. the results showed that the setting times increased with the increase of scoria replacement level for blaine fineness values of 2400 and 3200 cm2/g. the effect is more pronounced when the scoria content is used at 35% as cement replacement. for example, the highest retardation of the initial & final setting times at this percentage were 177 min and 211 min for 2400 cm2/g and 158 min and 188 min for 3200 cm2/g, respectively. this could be due to the pozzolanic reaction between pozzolan and ch liberated during hydration of c3s and c2s of clinker, which is usually slower than the hydration of cement (adesanya & raheem 2009). some researchers related the delay in setting times when using natural pozzolan with the increase of water requirements (colak 2003). on the contrary, scoria-based blended cements with 4200 and 5100 cm2/g blaine fineness values showed a quit different trend. the setting times decreased with increasing the scoria replacement level. this behavior is difficult to explain by authors, but according to some authors this may be attributed to a set of reasons as follows: a) the increasing surface area of scoria content of the paste results in greater interparticle contact, thus speeds up setting (targan et al. 1995), b) the hydration reaction of pozzolan blended cement is diffusion-controlled (plowman & cabrera, 1984). blaine fineness values of 4200 and 5100 cm2/g with scoria content of 25% up to 35% might had accelerated diffusion of water and dissolution of c3a, and increased the transition of ca 2+ ion into soluble state in water, thus the crystallization rate of cshs increased and the setting time was shortened (sidheswaran & bhat, 1997). furthermore, a similar trend has been reported by other researchers table 2 physical properties of cements used in the experiments blaine fineness (cm2/g) cement type initial setting (min) final setting (min) water demand (%) soundness (mm) residue on 45 µm sieve (%) residue on 90 µm sieve (%) 2400 c1/cem i 166 199 24.2 1 15.3 7.6 c2/25% 171 198 24.8 0.8 18.2 7.9 c3/30% 170 202 24.8 1 18.3 8.3 c4/35% 177 211 25.1 0.9 19.7 8.1 3200 c1/cem i 151 178 25.1 0.6 13.6 6.4 c2/25% 152 179 25.4 0.9 16.1 6.7 c3/30% 153 181 25.4 1.1 17.0 6.9 c4/35% 158 188 25.5 0.9 17.9 6.8 4200 c1/cem i 133 172 26.2 0.5 9.10 5.0 c2/25% 126 165 26.7 0.31 9.90 5.50 c3/30% 124 166 27.0 0.26 10.3 5.70 c4/35% 127 162 27.5 0.29 10.5 5.80 5100 c1/cem i 114 163 27.1 0.35 7.00 2.10 c2/25% 106 152 27.2 0.19 7.20 2.40 c3/30% 105 147 27.7 0.18 7.30 2.50 c4/35% 116 147 27.9 0.15 7.5 2.60 journal of sustainable architecture and civil engineering 2015/4/13 54 for blaine fineness value of 4200 cm2/g and relatively high cement replacement levels (ghrici et al. 2006). the natural pozzolan used in their experiments was of a chemical composition similar to that of the investigated volcanic scoria. it is also clearly seen from the results obtained that for the same replacement level, the initial setting times were reduced with the gradual increase in blaine fineness values. for instance, c30 with 2400 cm2/g blaine fineness had the initial setting time of 176 min and with 5100 cm2/g blaine fineness it had shorter initial setting time which was only 105 min. this seems to be in a well agreement with the literature (uzal & turanli, 2003; hago et al., 2002). further, the longer initial setting time at lower blaine fineness values may be due to the relatively coarser clinker particles in the interground blended cements (tsivilis et al., 1992). it is worthwhile to mention that from the results obtained, all the scoria-based binders are seen to comply with the standard requirements (initial setting time ≥45 min and final setting time≤420 min, according to (astm c595) for all blaine fineness values. a plot of the initial setting time against the final setting time for the whole tested samples as shown in (fig. 3) indicates that there is a strong correlation between the parameters as the coefficient of correlation (r2) was calculated to be 0.94. a strong relationship exists between two variables when r2≥0.85 (montogomery 1982). thus, an estimate of the final setting time can be predicted from the eq. (1) when the initial setting time has been obtained. fig. 3 correlation between initial and final setting times of the investigated pastes where: fst=final setting time (min); ist=initial setting time (min). (1)fst=0.79 ist + 64.5 (r2=0.94) volume expansion cao and mgo compounds that exist freely in cement may create a swelling effect and therefore their presence should be limited. since the free lime ratio will decrease as the natural pozzolan addition ratio increase, a decrease in the soundness can be expected. results of the experiments conducted to see these effects are presented in (table 2). estigated pastes table 2). samples having higher amounts of scoria show a noticeable drop compared to the control, particularly with 4200 and 5100 cm2/g blaine fineness, which shows that finer scoria-based cement can make an important contribution to concrete durability. interpretation of these results needs further investigation, although all soundness results were much less than 10 mm as specified in en 197-1. 3.3. mechanical strengths of mortars 3.3.1. compressive strength the compressive strength results of all mortar mixes containing varying amounts of scoria are arranged in (table 3). as expected, all mortars, with and without scoria show an increase in strength with curing time. mortar specimens containing cem i have higher compressive strengths at any age when compared to scoria-based cement mortars. also, it is seen that as the scoria replacement level increases as the compressive strength of scoria-based cement mortars decreases for all curing times. for instance, the compressive strength of cement mortars with 3200 cm2/g blaine fineness at 7 days decreased from 30.57 to 19.99 mpa when cem i and c4/35% were used, respectively. this could be explained by the slowness of the pozzolanic reaction between the glassy phase in scoria and the ch released during cement hydration. however, due to the continuation of this reaction and the formation of a secondary c-s-h, a greater degree of hydration is achieved resulting in strengths after 90 days curing which are comparable to those of cem i specimens (al-swaidani & aliyan, 2015). it should also be noted that the reductions in strengths of blended cement mortars were considerable at 2, 7 and 28 days; however, the difference narrowed by the age 90 days due to progress of the pozzolanic reaction with age in blended cements. for instance, the compressive strength of c2/25% with 3200 cm2/g blaine fineness was found to be 19% lower than cem i at 2 days curing, but this reduction was only 6% after 90 days curing. table 3. compressive strengths development of all cement mortars with curing times cement type blaine fineness (cm2/g) compressive strength (mpa)-normalized 2 days curing 7 days curing 28 days curing 90 days curing c1/cem i 2400 10.89-100% 23.63-100% 37.36-100% 46.85-100% 3200 15.4-141.4% 30.57-129.4% 45.6-122.1% 54.48-116.3% 4200 22.33-205.1 35.42-149.9% 48.23-129.1% 57.36-122.4% 5100 25.7-236% 40.03-169.4 53.45-143.1% 61.4-131.1% c2/25% 2400 9.09-100% 19.83-100% 30.08-100% 43.21-100% 3200 12.54-138% 23.46-118.3% 37.03-123.1% 51.3-118.7% 4200 20.15-221.6% 31.78-160.3% 43.67-145.2% 56.81-131.4% 5100 22.21-244.3% 34.03-171.6% 45.33-150.7% 59.35-137.4% fst = 0.79ist + 64.5 r² = 0.94 0 50 100 150 200 250 0 50 100 150 200 fi na l s et tin g tim e (m in ) initial setting time (min) according to the experimental results, soundness decreases as the scoria content increase. the volume expansions of samples having higher amounts of scoria show a noticeable drop compared to the control, particularly with 4200 and 5100 cm2/g blaine fineness, which shows that finer scoria-based cement can make an important contribution to concrete durability. interpretation of these results needs further investigation, although all soundness results were much less than 10 mm as specified in en 197-1. mechanical strengths of mortars compressive strength the compressive strength results of all mortar mixes containing varying amounts of scoria are arranged in (table 3). as expected, all mortars, with and without scoria show an increase in strength with curing time. mortar specimens containing cem i have higher compressive strengths at any age when compared to scoria-based cement mortars. also, it is seen that as the scoria replace55 journal of sustainable architecture and civil engineering 2015/4/13 ment level increases as the compressive strength of scoria-based cement mortars decreases for all curing times. for instance, the compressive strength of cement mortars with 3200 cm2/g blaine fineness at 7 days decreased from 30.57 to 19.99 mpa when cem i and c4/35% were used, respectively. this could be explained by the slowness of the pozzolanic reaction between the glassy phase in scoria and the ch released during cement hydration. however, due to the continuation of this reaction and the formation of a secondary c-s-h, a greater degree of hydration is achieved resulting in strengths after 90 days curing which are comparable to those of cem i specimens (al-swaidani & aliyan, 2015). it should also be noted that the reductions in strengths of blended cement mortars were considerable at 2, 7 and 28 days; however, the difference narrowed by the age 90 days due to progress of the pozzolanic reaction with age in blended cements. for instance, the compressive strength of c2/25% with 3200 cm2/g blaine fineness was found to be table 3 compressive strengths development of all cement mortars with curing times cement type blaine fineness (cm2/g) compressive strength (mpa)-normalized 2 days curing 7 days curing 28 days curing 90 days curing c1/cem i 2400 10.89-100% 23.63-100% 37.36-100% 46.85-100% 3200 15.4-141.4% 30.57-129.4% 45.6-122.1% 54.48-116.3% 4200 22.33-205.1 35.42-149.9% 48.23-129.1% 57.36-122.4% 5100 25.7-236% 40.03-169.4 53.45-143.1% 61.4-131.1% c2/25% 2400 9.09-100% 19.83-100% 30.08-100% 43.21-100% 3200 12.54-138% 23.46-118.3% 37.03-123.1% 51.3-118.7% 4200 20.15-221.6% 31.78-160.3% 43.67-145.2% 56.81-131.4% 5100 22.21-244.3% 34.03-171.6% 45.33-150.7% 59.35-137.4% c3/30% 2400 8.04-100% 16.95-100% 26.43-100% 40.54-100% 3200 11.07-137.7% 21.26-125.4% 33.74-127.7% 49.35-121.7% 4200 17.41-216.5% 27.57-162.7% 39.38-149% 54.56-134.6% 5100 19.57-243.4% 29.97-176.8% 42.35-160.2% 56.91-140.4% c4/35% 2400 7.37-100% 15.69-100% 25.88-100% 39.37-100% 3200 10.09-136.9% 19.99-127.4% 30.56-118.1% 47.57-120.8% 4200 16.19-219.7% 25.38-161.8% 35.96-138.9% 51.73-131.4% 5100 18.12-245.9% 27.68-176.4% 41.08-158.7% 55.1-140% 19% lower than cem i at 2 days curing, but this reduction was only 6% after 90 days curing. the fineness of cement is a major factor influencing its rate of hydration, since the hydration reaction occurs at the interface with water (hewlett 1998). greater cement fineness increases the rate at which cement hydrates and thus accelerates strength development. the effects of greater fineness on mortar strength are manifested principally at the early ages. based on the results presented in (table 3), prolonged grinding of the scoria-based blended cements from 2400 to 5100 cm2/g blaine fineness increased the compressive strength by144 %, 143% and 146% at 2 days curing and by 72 %, 77% and 76% at 7days curing but only by 37%, 40% and 40% at 90 days curing for c2/25%, c3/30% and c4/35%, respectively. this could be explained by the effect of grinding which breaks the vitreous body and increases their surface area, resulting in higher activity (chen, 2007). in addition, according to shi (2001) prolonged grinding decreases the particle size and increases dissolution rate and solubility of natural pozzolan, which will accelerate pozzolanic reaction rate and strength development of mortar containing natural pozzolan. further, when clinker and natural pozzolans are interjournal of sustainable architecture and civil engineering 2015/4/13 56 ground, the finer portion of the blended cement is mostly ground natural pozzolan whereas the coarse portion is mostly ground clinker (binici et al., 2007). this could be confirmed by the high porosity of the studied volcanic scoria which may be an advantage for easy and economical crushing (kelling et al. 2000). strong correlation coefficients of more than 0.9 were obtained if a straight line is fitted to the experimental data, as illustrated in fig. 4-7. as shown in fig. 4-7 there is a linear increase in strength as the blaine fineness increases irrespective of the curing time. it is clearly seen in fig 4-7 that all blendfig. 4 correlation between compressive strength of cem i mortar and blaine fineness of cement at different curing times fig. 5 correlation between compressive strength of c2/25% mortar and blaine fineness of cement at different curing times fig. 6 correlation between compressive strength of c3/30% mortar and blaine fineness of cement at different curing times c3/30% 2400 8.04-100% 16.95-100% 26.43-100% 40.54-100% 3200 11.07-137.7% 21.26-125.4% 33.74-127.7% 49.35-121.7% 4200 17.41-216.5% 27.57-162.7% 39.38-149% 54.56-134.6% 5100 19.57-243.4% 29.97-176.8% 42.35-160.2% 56.91-140.4% c4/35% 2400 7.37-100% 15.69-100% 25.88-100% 39.37-100% 3200 10.09-136.9% 19.99-127.4% 30.56-118.1% 47.57-120.8% 4200 16.19-219.7% 25.38-161.8% 35.96-138.9% 51.73-131.4% 5100 18.12-245.9% 27.68-176.4% 41.08-158.7% 55.1-140% the fineness of cement is a major factor influencing its rate of hydration, since the hydration reaction occurs at the interface with water (hewlett 1998). greater cement fineness increases the rate at which cement hydrates and thus accelerates strength development. the effects of greater fineness on mortar strength are manifested principally at the early ages. based on the results presented in (table 3), prolonged grinding of the scoria-based blended cements from 2400 to 5100 cm2/g blaine fineness increased the compressive strength by144 %, 143% and 146% at 2 days curing and by 72 %, 77% and 76% at 7days curing but only by 37%, 40% and 40% at 90 days curing for c2/25%, c3/30% and c4/35%, respectively. this could be explained by the effect of grinding which breaks the vitreous body and increases their surface area, resulting in higher activity (chen, 2007). in addition, according to shi (2001) prolonged grinding decreases the particle size and increases dissolution rate and solubility of natural pozzolan, which will accelerate pozzolanic reaction rate and strength development of mortar containing natural pozzolan. further, when clinker and natural pozzolans are interground, the finer portion of the blended cement is mostly ground natural pozzolan whereas the coarse portion is mostly ground clinker (binici et al., 2007). this could be confirmed by the high porosity of the studied volcanic scoria which may be an advantage for easy and economical crushing (kelling et al. 2000). fig. 4. times fc = 0.0056bf 2.4632 r² = 0.98 fc = 0.0059bf + 10.402 r² = 0.98 fc = 0.0055bf + 25.538 r² = 0.94 fc= 0.0051bf + 36.168 r² = 0.93 0 10 20 30 40 50 60 70 0 1000 2000 3000 4000 5000 6000 c om pr es si ve s tr en gt h of m or ta r (m pa ) blaine fineness (cm2/g) 2 days curing 7 days curing 28 days curing 90 days curing fig.5 strong correlation coefficients of more than 0.9 were obtained if a straight line is fitted to the experimental data, as illustrated in fig. 4-7. as shown in fig. 4-7 there is a linear increase in strength as the blaine fineness increases irrespective of the curing time. it is clearly seen in fig 4-7 with the increase in curing time. further, it is worth noting that the significant gain in strength in blended cement mortars occurred when moving from 28 to 90 days curing times while in cem i specimens this was noted during the first 28 days. this could be explained by the slow pozzolanic reaction and its progress with age in blended cement mortars. in addition, it is evidently seen that moving from 3200 cm2/g (which is a customary value in cement production) to 4200 cm2/g blaine fineness had a very obvious influence on the results, whereas this influence was less marked when the blaine fineness increased from 4200 to 5100 cm2/g. fig.6. correlation between compressive strength of c3/30% mortar and blaine fineness of cement at different curing times fc = 0.0052bf 3.2964 r² = 0.963 fc = 0.0056bf + 6.3526 r² = 0.962 fc = 0.0057bf + 17.674 r² = 0.937 fc = 0.0059bf + 30.748 r² = 0.937 0 10 20 30 40 50 60 70 0 1000 2000 3000 4000 5000 6000 c om pr es si ve st re ng th o f m or ta r (m pa ) blaine fineness (cm2/g) 2 days curing 7 days curing 28 days curing 90 days curing fc = 0.0045bf 2.7849 r² = 0.973 fc = 0.005bf + 5.3603 r² = 0.97 fc= 0.0058bf + 13.737 r² = 0.958 fc = 0.0059bf + 28.297 r² = 0.919 0 10 20 30 40 50 60 70 0 1000 2000 3000 4000 5000 6000 c om pr es si ve st re ng th o f m or ta r (m pa ) blaine fineness (cm2/g) 2 days curing 7 days curing 28 days curing 90 days curing fig.5. correlation between compressive strength of c2/25% mortar and blaine fineness of cement at different curing times strong correlation coefficients of more than 0.9 were obtained if a straight line is fitted to the experimental data, as illustrated in fig. 4-7. as shown in fig. 4-7 there is a linear increase in strength as the blaine fineness increases irrespective of the curing time. it is clearly seen in fig 4-7 that all blended cement mortars exhibited steeper slops with the increase in curing time. further, it is worth noting that the significant gain in strength in blended cement mortars occurred when moving from 28 to 90 days curing times while in cem i specimens this was noted during the first 28 days. this could be explained by the slow pozzolanic reaction and its progress with age in blended cement mortars. in addition, it is evidently seen that moving from 3200 cm2/g (which is a customary value in cement production) to 4200 cm2/g blaine fineness had a very obvious influence on the results, whereas this influence was less marked when the blaine fineness increased from 4200 to 5100 cm2/g. fig.6 curing times fc = 0.0052bf 3.2964 r² = 0.963 fc = 0.0056bf + 6.3526 r² = 0.962 fc = 0.0057bf + 17.674 r² = 0.937 fc = 0.0059bf + 30.748 r² = 0.937 0 10 20 30 40 50 60 70 0 1000 2000 3000 4000 5000 6000 c om pr es si ve st re ng th o f m or ta r (m pa ) blaine fineness (cm2/g) 2 days curing 7 days curing 28 days curing 90 days curing fc = 0.0045bf 2.7849 r² = 0.973 fc= 0.0058bf + 13.737 r² = 0.958 fc = 0.005bf + 5.3603 r² = 0.97 fc = 0.0059bf + 28.297 r² = 0.919 0 10 20 30 40 50 60 70 0 1000 2000 3000 4000 5000 6000 c om pr es si ve st re ng th o f m or ta r (m pa ) blaine fineness (cm2/g) 2 days curing 7 days curing 28 days curing 90 days curing 57 journal of sustainable architecture and civil engineering 2015/4/13 fig. 7 correlation between compressive strength of c4/35% mortar and blaine fineness of cement at different curing times fig.7 table 4 cement type blaine fineness (cm2 c1/cem i 2400 3200 4.27-117% 7.05-110% 7.94-106% 8.32-105% 4200 4.73-130% 7.28-114% 8.3-111% 8.57-108% 5100 4.92-135% 7.35-115% 8.4-112% 8.69-110% c2/25% 2400 2.95-100% 5.66-100% 6.81-100% 7.46-100% 3200 3.59-122% 6.08-107% 7.16-105% 7.78-104% 4200 4.13-140% 6.43-114% 7.47-110% 7.99-107% 5100 4.28-145% 6.45-114% 7.53-111% 8.03-108% c3/30% 2400 2.67-100% 5.29-100% 6.51-100% 7.29-100% 3200 3.25-122% 5.71-108% 6.91-106% 7.69-105% 4200 3.94-148% 5.99-113% 7.31-112% 7.87-108% 5100 4.02-150% 6.07-115% 7.38-113% 7.79-107% c4/35% 2400 2.53-100% 4.85-100% 6.26-100% 7.04-100% 3200 3.09-122% 5.37-111% 6.61-106% 7.42-105% 4200 4.01-158% 5.98-123% 7.33-117% 7.81-111% 5100 4.09-162% 5.95-123% 7.36-118% 7.85-112% 3.3.2. flexural tensile strength results of flexural tensile strength of the prisms prepared from the produced mortars and cured in water until the test dates are arranged in (table 4). the values given in the table show the average of flexural tensile strength for 3 samples. a similar trend to that observed for compressive strength seems to be followed by the flexural strength results. however, the results show that flexural strength is less sensitive than the compressive strength to the binder’ blaine fineness. 3.3.3. correlation between compressive and flexural strength the relationship between the compressive strength (fc) and flexural strength (ft) is given in (fig. 8) and seems to fit well with the relation proposed by aci 363r (1992). ft= k(fc)a (2) the correlation between the flexural strength and the compressive strength results were calculated for the entire population of test results and hence the relation obtained is: ft= 0.90×(fc)0.56 (3) with a correlation factor of 0.92. so, knowing the compressive strength fc of mortar the flexural strength ft can be predicted by using eq. (3). fc = 0.0042bf 2.8132 r² = 0.969 fc = 0.0045bf+ 5.2718 r² = 0.978 fc = 0.0056bf + 12.506 r² = 0.999 fc= 0.0056bf + 27.611 r² = 0.938 0 10 20 30 40 50 60 70 0 1000 2000 3000 4000 5000 6000 c om pr es si ve st re ng th o f m or ta r (m pa ) blaine fineness (cm2/g) 2 days curing 7 days curing 28 days curing 90 days curing ed cement mortars exhibited steeper slops with the increase in curing time. further, it is worth noting that the significant gain in strength in blended cement mortars occurred when moving from 28 to 90 days curing times while in cem i specimens this was noted during the first 28 days. this could be explained by the slow pozzolanic reaction and its progress with age in blended cement mortars. in addition, it is evidently seen that moving from 3200 cm2/g (which is a customary value in cement production) to 4200 cm2/g blaine fineness had a very obvious influence on the results, whereas this influence was less marked when the blaine fineness increased from 4200 to 5100 cm2/g. table 4 flexural strengths development of all cement mortars with curing times cement type blaine fineness (cm2/g) flexural strength (mpa)-normalized 2 days curing 7 days curing 28 days curing 90 days curing c1/cem i 2400 3.65-100% 6.4-100% 7.5-100% 7.92-100% 3200 4.27-117% 7.05-110% 7.94-106% 8.32-105% 4200 4.73-130% 7.28-114% 8.3-111% 8.57-108% 5100 4.92-135% 7.35-115% 8.4-112% 8.69-110% c2/25% 2400 2.95-100% 5.66-100% 6.81-100% 7.46-100% 3200 3.59-122% 6.08-107% 7.16-105% 7.78-104% 4200 4.13-140% 6.43-114% 7.47-110% 7.99-107% 5100 4.28-145% 6.45-114% 7.53-111% 8.03-108% c3/30% 2400 2.67-100% 5.29-100% 6.51-100% 7.29-100% 3200 3.25-122% 5.71-108% 6.91-106% 7.69-105% 4200 3.94-148% 5.99-113% 7.31-112% 7.87-108% 5100 4.02-150% 6.07-115% 7.38-113% 7.79-107% c4/35% 2400 2.53-100% 4.85-100% 6.26-100% 7.04-100% 3200 3.09-122% 5.37-111% 6.61-106% 7.42-105% 4200 4.01-158% 5.98-123% 7.33-117% 7.81-111% 5100 4.09-162% 5.95-123% 7.36-118% 7.85-112% flexural tensile strength results of flexural tensile strength of the prisms prepared from the produced mortars and cured in water until the test dates are arranged in (table 4). the values given in the table show the average of flexural tensile strength for 3 samples. a similar trend to that observed for compressive strength seems to be followed by the flexural strength results. however, the results show that flexural strength is less sensitive than the compressive strength to the binder’ blaine fineness. journal of sustainable architecture and civil engineering 2015/4/13 58 correlation between compressive and flexural strength the relationship between the compressive strength (fc) and flexural strength (ft) is given in (fig. 8) and seems to fit well with the relation proposed by aci 363r (1992). (2)ft=k(fc) a (3)ft= 0.90×(fc) 0.56 the correlation between the flexural strength and the compressive strength results were calculated for the entire population of test results and hence the relation obtained is: with a correlation factor of 0.92. so, knowing the compressive strength fc of mortar the flexural strength ft can be predicted by using eq. (3). fig. 8 correlation between flexural and compressive strengths of the investigated mortars fig. 8. 3.4. correlation between mechanical strengths and blaine fineness fig. 4-7 illustrate the dependence of the compressive strength on the blaine fineness of the cements used. based on curve fitting by the least square method, the relationships agreed well with linear functions (fig. 4-7). as shown in fig. 4-7 the mortar strength increases linearly with the increase in blaine fineness for all curing times. according to the test results, the mechanical strengths of mortars containing volcanic scoria-based cements seem to have a close relationship with the binder’ blaine fineness. so, the compressive and flexural strengths of cem ii/b-p-based mortars at a given curing time can be predicted from a knowledge of the blaine fineness. the general correlation formulas between each compressive strength and flexural strength and blaine fineness can be expressed as follows: fc; ft=(a×lnt+b)×bf+c×lnt+d (4) where fc, ft are compressive and flexural strength of mortars in (mpa), respectively; t is the curing time in (days); bf is the blaine fineness of the produced cement (cm2/g) and a, b, c and d are constants. table 5. constants a, b, c and d and regression coefficients (r2) of the correlation between the experimental data and the proposed equation. cement type a b c d r2 c1/cem i fc -1×10-4 0.0059 10.242 -9.40 0.989 ft -5×10-5 0.0005 1.1773 2.5578 0.841 c2/25% fc 2×10-4 0.0052 8.8416 -10.276 0.988 ft -7×10-5 0.0005 1.2989 1.6536 0.905 c3/30% fc 4×10-4 0.0043 7.8982 -9.5233 0.982 ft -7×10-5 0.0005 1.3616 1.1907 0.934 c4/35% fc 4×10-4 0.0039 7.6476 -9.3758 0.981 ft -7×10-5 0.0006 1.330 0.6931 0.952 table 5 presents the constants (a, b, c and d) with regression coefficients of the correlation between the experimental data and the proposed equation. however, it should be emphasized that additional factors including the type of natural pozzolan, composition and strength of clinker may also be effective on the mechanical properties of mortar. further, it is worth noting that an increase of about 5 mpa can be expected for every 1000 cm2/g increase in blaine fineness for cem ii/b-p-based mortars at all curing times. 4. conclusion based on the experimental results, the following conclusions could be drawn: -it can be said that the volcanic scoria deposits located in the studied site is a perfect potential for the cement industry. volcanic scoria had more than of major chemical components, sio2 + al2o3 + fe2o3, conforming to the chemical requirements of the astm and en standards. in addition, the experimental results presented in this paper showed the physical characteristics of the cement containing scoria are in conformity with the standards requirements and that the strength of scoria-based cements is lower than the plain portland cement at early ages, but can reach the same order of strength at longer ages. ft = 0.90fc0.56 r² = 0.92 0 2 4 6 8 10 0 10 20 30 40 50 60 70 fl ex ur al s tr en gt h of m or ta r (m pa ) compressive strength of mortar (mpa) correlation between mechanical strengths and blaine fineness fig. 4-7 illustrate the dependence of the compressive strength on the blaine fineness of the cements used. based on curve fitting by the least square method, the relationships agreed well with linear functions (fig. 4-7). as shown in fig. 4-7 the mortar strength increases linearly with the increase in blaine fineness for all curing times. according to the test results, the mechanical strengths of mortars containing volcanic scoria-based cements seem to have a close relationship with the binder’ blaine fineness. so, the compressive and flexural strengths of cem ii/b-p-based mortars at a given curing time can be predicted from a knowledge of the blaine fineness. the general correlation formulas between each compressive strength and flexural strength and blaine fineness can be expressed as follows: (4)fc; ft=(a×lnt+b)×bf+c×lnt+d table 5 presents the constants (a, b, c and d) with regression coefficients of the correlation between the experimental data and the proposed equation. however, it should be emphasized that additional factors including the type of natural pozzolan, composition and strength of clinker may also be efwhere fc, ft are compressive and flexural strength of mortars in (mpa), respectively; t is the curing time in (days); bf is the blaine fineness of the produced cement (cm2/g) and a, b, c and d are constants. table 5 constants a, b, c and d and regression coefficients (r2) of the correlation between the experimental data and the proposed equation. cement type a b c d r2 c1/cem i fc -1×10 -4 0.0059 10.242 -9.40 0.989 ft -5×10 -5 0.0005 1.1773 2.5578 0.841 c2/25% fc 2×10 -4 0.0052 8.8416 -10.276 0.988 ft -7×10 -5 0.0005 1.2989 1.6536 0.905 c3/30% fc 4×10 -4 0.0043 7.8982 -9.5233 0.982 ft -7×10 -5 0.0005 1.3616 1.1907 0.934 c4/35% fc 4×10 -4 0.0039 7.6476 -9.3758 0.981 ft -7×10 -5 0.0006 1.330 0.6931 0.952 fective on the mechanical properties of mortar. further, it is worth noting that an increase of about 5 mpa can be expected for every 1000 cm2/g increase in blaine fineness for cem ii/ b-p-based mortars at all curing times. 59 journal of sustainable architecture and civil engineering 2015/4/13 based on the experimental results, the following conclusions could be drawn: _ it can be said that the volcanic scoria deposits located in the studied site is a perfect potential for the cement industry. volcanic scoria had more than of major chemical components, sio2 + al2o3 + fe2o3, conforming to the chemical requirements of the astm and en standards. in addition, the experimental results presented in this paper showed the physical characteristics of the cement containing scoria are in conformity with the standards requirements and that the strength of scoria-based cements is lower than the plain portland cement at early ages, but can reach the same order of strength at longer ages. _ contrary to expectation, scoria-based blended cements with 4200 and 5100 cm2/g blaine fineness values exhibited shorter setting times with the increase of scoria replacement level. this behavior is difficult to explain by authors and it needs further investigation. _ the fineness of scoria-based cement is an activating property for the mortar mechanical strength, especially during the early ages. mechanical strengths of mortars were found to substantially increase with an increase in scoria-based cement fineness. for all curing times, it was concluded that the worst and best performance in terms of compressive strength was observed in the mortars produced with scoria-based cement with fineness of 2400 and 5100 cm2/g, respectively. _ prolonged grinding of the blended cements to achieve a blaine fineness beyond 4200 cm2/g (i. e. 5100 cm2/g) did not show significant influence on the mechanical strengths of blended cement mortars when compared to 4200 cm2/g. so, for reducing the costs of grinding, it is recommended as a result of this study to reach a blaine fineness of no more than 4200 cm2/g. _ it was evidently observed that in all mortars containing scoria, there was a noticeable gain in strength from 28 days onwards, while this was noted during the first 28 days in cem i specimens. _ based on the results obtained, the authors derived an estimation equation for compressive and flexural tensile strength development incorporating the effects of blaine fineness. the mechanical strength of mortar containing scoria-based cement can reasonably be predicted using the eq. (4). development of such a good relationship between mechanical strengths and the binder’ blaine fineness can be of considerable benefit. _ according to the results obtained, it is suggested that volcanic scoria can be used up to 35% as a partial substitute for portland cement in production of blended cements when interground to blaine fineness of 4200 cm2/g or more if the cost of grinding can be neglected. this addition ratio can provide economical and ecological benefits due to less use of cement and less co2 emission from production of cement. so, production of greener concrete could be promoted. conclusions the authors gratefully acknowledge the technical and financial support of this research from the management of general organization for cement and building materials/ adra cement plant. thanks are also expressed to eng. amjad bernieh (lafarge co.) and prof. tamer al-hajeh, vice-president of aiu for their appreciated help. acknowledgment adesanya da., raheem aa., development of corn cob ash blended cement, construction and building materials, 2009; aitcin pc., mindess s. sustainability of concrete. taylor & francis, 2011 al-chaar gk., al-kadi m., asteris pg. natural pozzolan as a partial substitute for cement in concrete. the open construction and technology journal, 2013; 7: 33-42. references journal of sustainable architecture and civil engineering 2015/4/13 60 al-swaidani am., aliyan sd. effect of adding scoria as cement replacement on durability-related properties. international journal of concrete structures and materials, 2015, 9(2):241-254. binici h., aksogan o., cagatay ih., tokyay m., emsen e. the effect of particle size distribution on the properties of blended cements incorporating ggbfs and natural pozzolan (np), powder technology. 2007; 177:140-147. chen w., hydration of slag cement, phd thesis, university of twente, netherland, 2007. colak a., charecteristics of pastes from a portland cement containing different amounts of natural pozzolan, cement and concrete research, 2003, 33: 585-593. day rl., shi c. influence of the fineness of pozzolan on the strength of lime natural pozzolan cement pastes. cement and concrete research, 1994; 24(8):1485-1491. ghrici m., kenai s., meziane e., mechanical and durability properties of cement mortar with algerian natural pozzolana, journal of materials science, 2006; 41:6965-6972. hago aw., al-rawas aa., al-sidairi a., effect of the fineness of artificial pozzoaln (sarooj) on properties of lime-pozzoaln mixes, sultan qaboos university, 2002. hewlett pc. lea’s chemistry of cement and concrete. 4th edition, butterworth-heinemann, 1998. jaya rp et al., strength and permeability properties of concrete containing rice husk ash with diffirent grinding time, central european journal of engineering. 2011; 1(1):103-112. kelling g., kapur s., sakarya n., akca e., karaman c., sakarya b. basaltic tephra: potential new resource for ceramic industry. british ceramic trans. 2000; 99:129-136. khan ki, alhozaimy am. properties of natural pozzolan and its potential utilization in environmental friendly concrete. canad j civ eng, 2010; 38:71-78. kouloumbi n., batis g., pantazopulou p. efficiency of natural greek pozzolan in chloride-induced corrosion of steel reinforcement. cement and concrete aggregate, 1995; 17(1): 18-25 mehta pk., concrete, structure, properties and materials, prentice-hall, new jersy, 1986. montgomery dc., peck ea., introduction to linear regression analysis. new york: wiley, 1982. moufti m., sabtan a., el-mahdy o., shehata w. assessment of the industrial utilization of scoria materials in central harrat rahat. saudi arabia, eng geology, 2000; 57:155-162. neville am. properties of concrete. fifth edition, pearson education, 2011. plowman c., cabrera jg. mechanism and kinitics of hydration of c3a and c4af extracted from cement. cement and concrete research, 1984; 14:238. rossi g., forchielli l. porous structure and reactivity with lime of some natural italian pozzolans. ii cemento, 1976; 76:215-221. senhadji y., escadeillas g., khelafi h., mouli m., benosman a.s., evaluation of natural pozzolan for use as supplementary cementitious material, european journal of environmental and civil engineering, 2012; 16(1): 7796. shi c., an overview on the activation of the reactivity of natural pozzolans, can. j. civ. eng., 2001; 28:778-786. sidheswaran p., bhat an., impact of zeolitic water content on exchange of calcium ions, thermochimica acta, 1997; 298:55. targan s., olgun a., erdogan y., sevinc v., influence of natural pozzolan, colemanite ore waste, bottom ash, and fly ash on the properties of portland cement, cement and concrete research, 2003; 33: 1175-1182 the general establishment of geology and mineral resources in syria (gegmr), a guide for mineral resources in syria, 2011 (in arabic). the general establishment of geology and mineral resources in syria (gegmr), official document nr. (3207/t/9) dated 21.11.2007 (in arabic). the general organization for cement & building materials (gocbm), (www.cemsyria.com), accessed 2011 (in arabic). tsivilis s, tsimas s, moutsatsou a. contribution to the problems arising from the grinding of multicomponent cements. cem concr res 1992;22(1):95–102. uzal b., turanli l., studies on blended cements containing a high volume of natural pozzolans, cement and concrete research, 2003; 33:1777-1781. walker r., pavia s., physical properties and reactivivty of pozzolans and their influence on the properties of lime-pozzolan pastes, materials and structures, 2011; 44: 1139-1150. yetgin s., cavdar a. study of effects of natural pozzolan on properties of cement mortars, journal of materials in civil engineering, asce, 2006; 18(6):813-816. 61 journal of sustainable architecture and civil engineering 2015/4/13 aref m. al-swaidani assistant professor and vice-dean arab international (formerly european) university, faculty of architectural engineering, damascus, syria main research area building materials, concrete characteristics and technology, durability of rc structures, sustainability; supplementary cementing materials address faculty of architectural engineering, arab international university (aiu); mazzeh-high way across al-jalaa hotel phone: +963-11-6119341-7 fax: +963-11-6119340 e-mail: aydlswaidani@yahoo.fr; a-swaidani@aiu.edu.sy samira d. alyian senior engineer building department, sasmo; damascus, syria main research area: supplementary cementing materials; concrete constituents address: damascus, syria nazir adarnaly chemist quality department; general organization for cement and building materials main research area quality control; opc and blended cements address al-mazzeh, damascus, syria. about the authors journal of sustainable architecture and civil engineering 2016/2/15 76 *corresponding author: jurate.mockiene@ktu.lt microstructure and aging influence on the mechanical properties of high-voltage poles http://dx.doi.org/10.5755/j01.sace.15.2.16092 jūratė mockienė* department of building structures, kaunas university of technology studentu str. 48, lt51367 kaunas, lithuania audrius jutas department of mechanical engineering, kaunas university of technology studentu str.56, lt51424 kaunas, lithuania vilimantas vaičiukynas faculty of water and land management, aleksandras stulginskis university universiteto g.10, lt-53361 akademija, kaunas district municipality, lithuania received 2016/08/19 accepted after revision 2016/09/29 journal of sustainable architecture and civil engineering vol. 2 / no. 15 / 2016 pp. 76-84 doi 10.5755/j01.sace.15.2.16092 © kaunas university of technology microstructure and aging influence on the mechanical properties of highvoltage poles jsace 2/15 introduction high-voltage poles made in 1956 had to satisfy the cross-sectional geometry related standard (gost 850957 confirmed later). however, the stricter requirements weren’t applied for the microstructure. in this paper a strength analysis of the pillars’ material is provided. the technological specificities of profile manufacturing were mostly determined by differences in mechanical properties influenced by differences in microstructures of pillars’ material investigated. although the confirmed standard of steel ct3 (gost 380-71) had new requirements and clear criteria of microstructure acceptance but made pillars with the non-homogeneous microstructure remained standing. the differences in microstructural components create conditions for appreciable differences in mechanical properties such like yield stress and ultimate stress, fracture strain. in this paper, the limits of elastic and plastic strains are identified in order to quantify the changes in elastic and plastic properties with the differences in their intensity for selected step-like stress range. corrosion depth and width play the large role and ones often determine the fracture location of samples. the end of this work is dedicated to conclusion based on the relation of experimental part and analytical calculations presented. keywords: ageing, corrosion, microstructure, mechanical properties. the tensile properties of the alloys have been measured at room temperature as an expected function of corrosion level. investigation indicates that the very fine stable microstructure of the specimens’ material influences on mechanical properties combined with adequate corrosion impact. corrosion evolution on the cold-rolled low carbon steels is one of many examples of dynamics in corrosion that may occur under atmospheric/oxidizing conditions. cold forming operations and cold rolling generally do not decrease the corrosion resistance (barbier et al. 2009). it is important that such kind of steels do not demonstrate sufficient resistance to the corrosive effects of the most commonly encountered environment like atmosphere. in this article, authors present their study how level of corrosion may influence on mechanical properties after some period of maintenance time of high voltage piles. in electric industry, the 77 journal of sustainable architecture and civil engineering 2016/2/15 structures mentioned retain wide appearance of corrosion not only for long but also for short periods of time. data of this investigation was analyzed statistically, and a set of equations was derived that allows comparison of corrosion level as a function of the mechanical properties presented below (flower and lindley 2000). the height and roughness of exposed corrosion samples have been measured by mechanical profilometer for comparison with the results of fracture area gotten after tensile experiment. in some experimental studies, the averaged magnitude of corroded area has been used to image and map the corrosion under specimen surface and some authors showed that corrosion level may be described by the power function which is also suitable for demonstrating the development of long-term corrosion. (garcia et al. 2003). the mechanical properties and microstructures of low-carbon steel were investigated by tensile testing machine and optical microscopy, respectively. the results showed that significant differences existed in the yield strength, ultimate strength and fracture strength (arafin and szpunar 2009). the aim of the present work is to show the difference in mechanical properties for cold-rolled specimen made of law carbon steel and used in old design of high-voltage poles. the differences in microstructure and corrosion related damages influence on the dissipation of mechanical properties. used statistical method shows how experimental results are close to their mean values and what reasons of microstructural quality lead to those differences (serenelli et al. 2011, hughes et al. 2003). the present work is important for the development of statistical method that tries to overcome details of the differences in microstructure and level of corrosion on the specimen surface as a result of deformational state of material. the microstructural observations show that the difference of material quality naming it as a non-homogeneous specimen has a significant effect on different stages of deformation. the description of mechanical behaviour of crystalline material is a complex multiscale problem. while the underlying deformation processes such as the intergranural slip lead atomic plane inclinations and like-screw dislocations are microscopic problems, the measured results exhibit usually macroscopic stages. as it is presented in this work, provided tensile tests show a deformational behaviour of individual specimens. they also may exhibit that some level of corrosion over the area of the specimen is the reason of fracture. tensile test were provided using the standard lst en iso 6892-1:2009. the standard exhibits basic requirements for the methodology of test procedure like specimen geometry and speed of straining. during the test authors use deformation speed 1 mm/min. the result of the tests especially is important for an assessment of differences in deformational behaviour and it is one of the principal criteria of material quality of specimen. the principal mechanical properties were fixed using experimental curve “force vs. displacement” and calculated for individual specimens separately to find means presented in table 1. methods table 1 principal mechanical properties for family of tensile curves; averaged (see fig. 1) kind of stress/ strain stresses, mpa strains, % i ii iii iv a 300.6 300.6 0.4 0.4 b 429.3 573.2 9.1 32 c 354.9 669.9 12.2 71.2 journal of sustainable architecture and civil engineering 2016/2/15 78 for the statistical analysis, authors try to choose some alternative method on approximation of results and it is necessary to determine the values of the probability distribution over the variable experimental values changing their interval. it also influences on determination of the type of data distribution. in most cases the data are distributed according to the normal (gaussian) law. using hypothetical assumptions in statistical calculations, it is important to have some sufficient number of specimens. in the case of small number of specimens, there are some problems related usually with data normality. then, description or approximation of results is difficult. in determining the distribution type, authors assume that the data may be distributed by the normal distribution. normal distribution was defined by the arithmetic mean avex of mechanical properties and statistical analysis of their distributed values ix for some specimens’ set. therefore, in further analysis authors try to use that assumption of normal law and used criteria will provide some quality of analysis. the literature indicates that a rough estimation of the distribution determination is sufficient if number of experiments is at least 20. in our study there were 9 specimens tested. the individual statistical values ix are dissipated around the arithmetic mean value avex or around relative mean value 1=x with some probabilistic value ∆ and ones represent some density of points influencing on data normality. authors use simplified method how to visualize such kind of distribution by the equation fig. 1 family of tensile curves in terms of engineering (i/iii) and true (ii/ iv) stresses/strains, respectively. explanation of stress/strain state related letters: a is yielding, b is ultimate, c is fracture 0 50 100 150 200 250 300 350 400 450 500 550 0 5 10 15%, , mpa b c a 0 100 200 300 400 500 600 700 800 0 0,2 0,4 0,6 0,8 b s, mpa e, arb. m. u. c a i/iii ii/iv   %1001%10011 1 1                  i xx avex ix ix ix  (1) (2) for the approximation of expected statistical distribution of experimental results, following equation was used: where ave i i x x x = ; ∑= = n i iave xn x 1 1 ; ix is mechanical property related value of individual specimen used; 9...1=i . 12 3 1 21 ...   mnn mn m nnn xcxcxcxcxcy ; if 1 nm . 79 journal of sustainable architecture and civil engineering 2016/2/15 the parameter ∆ ( y=∆ ) was adopted to determine some expectation related probability of mechanical property that reaches maximal value at point 1=x . the final equation was chosen according to the maximal value of squared root deviation 2r for stresses and for strains, respectively, presented in the tables 2 and 3. in terms of stresses and strains, eq. 1 may by written as follows (3)   %1001%100 )( 11 1 1                   ixx avex ix ix ix        and eq. (2) adopted for stress looks like in table 2 there are constants ic presented according to relative mechanical property σx with the use of third order polynomial equations eq. (4). (4) 43 2 2 3 1 cxcxcxc   . table 2 relative mechanical properties σx and constants ic (×10 3) used in eq. 4 ci xσ c1 c2 c3 c4 r 2 a(i) 8.139 -6.212 28.000 -9.828 0.9816 b(i) 0* -0.832 1.676 -0.745 0.9824 c(i) 0* -0.832 1.676 -0.745 0.9824 a(ii) 8.139 -26.212 28.000 -9.828 0.9816 b(ii) 2.862 -9.583 10.574 3.754 0.9735 c(ii) 2.808 -9.373 10.309 -3.647 0.9409 in terms of stresses and strains, eq. 1 may by written as follows *-eq. 4 is transformed to second order equation (5)  %1001%100)(11 1 1                   ixx avex ix ix ix        . and eq. (2) applied for strains is similar with eq. (4) used for stresses: in table 3, there are constants ic presented according to relative mechanical property εx with the use of same structure polynomial equations eq. (6). (6) 43 2 2 3 1 cxcxcxc   . journal of sustainable architecture and civil engineering 2016/2/15 80 using equations 3 and 5 the values σ∆ and ε∆ were obtained and ones represent dots in the plotted graph of fig. 2. for those dots distributed around the relative mean 1=x in the left and right sides the equations of approximation eq. 5 and eq. 6 were applied. in fig. 2, i(a) the mostly dissipated engineering stress is stress b with its value 18.1=σx = 1.18 and %82=∆σ 82 %. also, for same enlarged distribution presented in fig. 2, i(b) the picks of engineering stress on the dashed mean line 1=x represents maximal values of that distribution related characteristics a, b and c. obviously, for a – ( ) %99max =∆σ 99 %, for b – ( ) %5.98max =∆σ 98.5 % and for c – ( ) %98max =∆σ 98 %. in the case of true stress (see fig. 2, ii(a)), the characteristics a and c are dissipating mostly with the values 15.1=σx 1.15, %85=∆σ 85 % and 85.0=σx 0.85, %85=∆σ 85 %, respectively. enlarged view (fig. 2, ii(b)) shows approximately same values for σ∆ in comparison with engineering stress mentioned above but dots are dissipated widely along to axis σx . this fact is related to the differences in methods for stresses used non-/reducing area of cross-section. in fig. 2. graphs iii and iv exhibit families of engineering and true strains, respectively. the largest difference was gotten for curve a representing engineering yield strain at the highest pick of yield stress yσ (fig. 2, iii(a)). the dissipation was high enough 6.1=εx and its probability was very low %36=∆ε 36 %. in the shorter enlarged range (fig. 2, iii(b)), the picks reach following values: for a – ( ) %5.92max =∆ε 92.5 % but 97.0=εx 0.97, for b and c – ( ) %5.98max =∆ε 98.5 %. true strain curves show similar distribution of mechanical characteristics a, b and c but the points in the curves b and c are dissipated widely along to axis εx (fig. 2, iv(a)). in the case of true strains, the contraction of cross-section area changes pick of characteristic b with value ( ) %5.95max =∆ε 95.5 % while it was higher for engineering strain ( ) %5.98max =∆ε 98.5 %. table 3 mechanical properties εx and constants ic (×103) used in eq. 6 ci xε c1 c2 c3 c4 r 2 a(iii) 0.109 -0.520 0.703 -0.199 0.938 b(iii) 3.389 -11.331 12.488 -4.448 0.9435 c(iii) -2.357 6.033 -4.993 1.415 0.9678 a(iv) 0.109 -0.075 0.422 -0.161 0.938 b(iv) -0.091 -0.075 0.422 -0.161 0.937 c(iv) -2.436 6.317 -5.321 1.539 0.9529 to describe the effects during deformation within the microstructure caused by heterogeneity is difficult because of disorientation of atomic planes in the crystals. such analyses have difficulty accounting for the evolution of yield surfaces in the crystals that are first sources of plastic deformation. these effects were not taken into account but they were assumed naturally occurring as inevitable process. the microstructural heterogeneity is usually inherited from the crystallization if the carbon amount in the edge and in the centre of steel ingot is different. iron oxides influence on the mechanical properties much stronger because of the joining fireplaces of those oxides inside the material. in the case of large amount of oxides, those fireplaces can easily connect by themselves and give a star to an earlier material degradation. the oxides especially are dangerous if their amounts are distributed stochastically inside the microstructure. results 81 journal of sustainable architecture and civil engineering 2016/2/15 after examination of the fracture photos the irregular damage of material along the tested samples which surface affected by long-term corrosion was revealed. as a result the characteristic parameters of corrosion defects were determined: such as the corrosion level, the approximate area of the damage, the intensity of corrosion and so on. on the surface of observed samples corrosion damage area and volume increase was examined according to the regulations of europe standard for metal and alloy corrosion and so on (lst en iso 8403:2000). fig. 2 parameters representing statistical distribution of relative stresses σx and strains εx versus related probabilistic values σ∆ and ε∆ , respectively. explanation of letters used: i and ii are engineering and true stresses; iii and iv are engineering and true strains; (a) is full set of results and (b) is enlarged view for chosen bi-axial range of figure (a) i(a) i(b) ii(a) ii(b) iii(a) iii(b) iv(a) iv(b) 80 85 90 95 100 0,8 0,9 1 1,1 1,2 b a c  ,% x 95 96 97 98 99 100 0,9 0,95 1 1,05 1,1 b a c x  ,% 80 85 90 95 100 0,8 0,9 1 1,1 1,2 b a c  ,% x 95 96 97 98 99 100 0,9 0,95 1 1,05 1,1 b a c  ,% x 30 40 50 60 70 80 90 100 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8 b a c  ,% x 90 91 92 93 94 95 96 97 98 99 100 0,8 0,9 1 1,1 1,2 b a c  ,% x 30 40 50 60 70 80 90 100 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8 b a c  ,% x 90 91 92 93 94 95 96 97 98 99 100 0,8 0,9 1 1,1 1,2 b a c  ,% x where: r is the estimate of corrosion on any surface (area); a is the relative area of any surface coated with corrosion defects. (7)r = 3(2 – log10 a) journal of sustainable architecture and civil engineering 2016/2/15 82 data of this investigation presented in fig. 3. the study found the dispersion of corrosion spots and the differences of intensity damage (cracks) on the sample surface or the surface layer. by using the photoshop program the rust area of ten samples was calculated. in calculating area, the program self-identified rusty color intensity of its surface area. then this program calculated the area of pixels, and later pixels was converted into area units (cm2) according the known area. the area of rust was calculated on ten samples by choosing the rustiest spots of investigated samples. the study found that the rusty area of individual samples varied in the range of 0.26 cm2 to 3.06 cm2 (fig. 3). the area of average rusty was 1.24 cm2, or 31% calculating from the measured area. by identifying rust damage spot the cleaning of sample surface could be affected on the size of dispersion. all samples have similar microstructure like steel ct 3 (gost). many of the studied samples are microstructuraly inhomogeneous, that is, in the microstructure there were found areas with a lower carbon amount of about 0.1% c, and areas with a higher carbon amount reaching 0.3% c. those inaccuracies were the primary sources of material fracture presenting in fig. 4. samples containing more homogeneous microstructure had quantity of carbon equal to 0.14−0.22%. it is obvious looking at microstructures presented in fig. 5. correlation between depth of corrosion and area of fracture is weak enough as it is shown in fig. 5. in the microstructures, there is some amount of other kind of defects like non−metallic inclusions (iron oxides and sulphides, decarbonizes surface layer, bandwidth and “widmanstatten” pattern). fig. 3 the diagram of corrosion area (a, cm2) influencing on indicator of corrosion affects r. notes: 1-9 are numbers of specimens fig. 4 the curves showing how a maximal depth of corrosion measured influences on the fracture point along to individual specimen length under tensile test 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 0,45 0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 114 120 126 132 138 144 150 156 specimen length, mm c or ro si on d ep th , m m no.1 no.2 no.3 no.4 no.5 no.6 no.7 no.8 no.9 1 2 3 9 5 7 4 6 8 2 1 3 4 5 9 8 7 6 -maximal corrosion depth -fracture point 83 journal of sustainable architecture and civil engineering 2016/2/15 conclusions fig. 5 pictures representing differences in microstructure and phenomena in the area of fracture, material ct3 (gost 380−71): a − homogeneous microstructure; b – non homogeneous microstructure; c − area of fracture non−metallic inclusions are inserted themselves in all samples as both oxides and sulphides. plastic sulphides are not seen in all samples. the negative effects are usually manifested in those cases if they are located in the transverse direction of the load. in the rolled profiles, these inclusions are parallel to the rolling direction. the influence of sulphides’ amount distributed along to rolling direction on the mechanical properties is weak. according to research it was conducted that the rusty area of individual samples varied in the range from 0.26 cm2 until 3.06 cm2 and the area of average rusty 1.24 cm2 was or 31%, calculating from the measured area. investigation shows that differences in microstructure caused by differences in its homogeneity were the primary reason of material fracture. in the tested steel samples the microstructure was typical for steel ct 3 (gost), but many of the analyzed samples were non-homogeneous microstructuraly: c content varied from 0.1% to 0.3%. it was likely that this non-homogeneity were the primary reason for the material fracture. such qualitative differences and imperfections create conditions for the strain instability appearing due to deformation showing wide distribution around relative means 1=σx and 1=εx . arafin, m. a., & szpunar, j. a. 2009. a new understanding of intergranular stress corrosion cracking resistance of pipeline steel through grain boundary character and crystallographic texture studies. corrosion science, 51(1), 119-128. http://dx.doi. org/10.1016/j.corsci.2008.10.006 barbier, d., gey, n., allain, s., bozzolo, n., & humbert, m. 2009. analysis of the tensile behavior of a twip steel based on the texture and microstructure evolutions. materials science and engineering: a, 500(1), 196-206.http://dx.doi.org/10.1016/j. msea.2008.09.031 flower, h. m., & lindley, t. c. 2000. electron backscattering diffraction study of acicular ferrite, bainite, and martensite steel microstructures. materials science and technology, 16(1), 26-40. http://dx.doi. org/10.1179/026708300773002636 garcía, i., conde, a., langelaan, g., fransaer, j., & celis, j. p. 2003. improved corrosion resistance references through microstructural modifications induced by codepositing sic-particles with electrolytic nickel. corrosion science, 45(6), 1173-1189. http://dx.doi. org/10.1016/s0010-938x(02)00220-2 hughes, d.a., hansen, n., d.j. bammann, d.j. 2003. geometrically necessary boundaries, incidental dislocation boundaries and geometrically necessary dislocations, scripta materialia, 48, pp. 147–153. http://dx.doi.org/10.1016/s13596462(02)00358-5 lst en iso 8403:2000. metallic coatings. coatings anodic to the substrate. rating of test specimens subjected to corrosion tests. serenelli, m.j., bertinetti, m.a., j.w. signorelli, j.w. 2011. study of limit strains for fcc and bcc sheet metal using polycrystal plasticity international journal of solids and structures, 48, pp. 1109–1119. http://dx.doi.org/10.1016/j.ijsolstr.2010.12.013 journal of sustainable architecture and civil engineering 2016/2/15 84 jūratė mockienė master degree, lektor department of building structures, kaunas university of technology. research interests steel structures, strength, durability, destruction, rational design. address kaunas university of technology, studentu st.48, lt51367 kaunas, lithuania. tel.+37068227397 e-mail: jurate.mockiene@ktu.lt audrius jutas dr., associate professor department of mechanical engineering, kaunas university of technology. research interests accident expertise, mechanics of materials, strength of materials, strength of structural elements address kaunas university of technology, studentų st.56, lt51424 kaunas, lithuania. tel.+37068378880 e-mail: audrius.jutas@ktu.lt about the authors vilimantas vaičiukynas dr., lektor institute of water resources engineering, aleksandras stulginskis university. research interest constructions of hydrotechnical structures, drainage materials, urban hydrology. address universiteto g.10, lt53361 akademija tel. +37061434230 e-mail: vilimantas.vaiciukynas@ asu.lt 25 journal of sustainable architecture and civil engineering 2017/3/20 *corresponding author: h.azizi66@hotmail.com the role of architecture in the process of moving towards sustainable development received 2017/06/19 accepted after revision 2017/11/03 journal of sustainable architecture and civil engineering vol. 3 / no. 20 / 2017 pp. 25-35 doi 10.5755/j01.sace.20.3.18406 © kaunas university of technology the role of architecture in the process of moving towards sustainable development jsace 3/20 http://dx.doi.org/10.5755/j01.sace.20.3.18406 mohammadhossein azizibabani*, marjan dehghani housing foundation of islamic revolution, tehran, iran environmental, social, and cultural problems arose in the twentieth century as a result of acceleration of industrial growth of societies as well as economic inequalities. lack of proper development patterns was the main factor demanding the introduction of the concept of sustainable development in the second half of the twentieth century. the construction industry, particularly the residential construction sector, was one of the major factors of energy consumption in the world. therefore, inclusion of the issue of sustainable development in this area and coupling housing development policies with the goal of sustainable development was of particular importance. in this regard, sustainability, as one of the most influential disciplines in the field of architecture, played an important role in order to meet the objectives of sustainable development. this paper reviewed the concepts of sustainable development and sustainable design, and addressed them in the field of architecture. the research method was descriptive-analytic, based on library information, and extracted data from the case studies. in this regard, the movements related to sustainable architecture have been categorized and characteristics of a sustainable building in terms of sustainable development goals have been outlined. the results showed the importance of the architecture in the process of moving towards sustainability. subsequently, an appropriate approach to meet the goals of sustainability in architectural design has been developed and potentials of this process to achieve sustainability have been mentioned. keywords: sustainable development, sustainable architecture, green building, renewable energies, building information modeling. introduction industrial development of communities challenged the human race with serious problems in various fields of environment, culture, and society. the adverse effects coupled with the acceleration of industrial growth in the twentieth century became more evident. environmental, economic and social issues such as increases in average global temperature, air and water pollution, and increased rate of migration from the countryside to towns, caused issues to arise due to differences in culture (abel, 2003). the main factors raising the sustainable development in the second half of the twentieth century are lifestyle of people in the social sphere, the confrontation with the truth of fossil fuel resources finitude, and the increasing price of these resources in the field of economy (unesco, 2012). in this regard, most of the experts believe that the only way to eliminate the problems caused by the rapid growth of industrial societies and the advancement of technology is moving towards achieving the goals of sustainable development (elington, 2004). journal of sustainable architecture and civil engineering 2017/3/20 26 nowadays, 40% of energy consumption and 50% of global raw materials have been allocated to buildings (attmann, 2010). buildings are responsible for producing 36 percent of the waste in the world (bauer and mösle, 2010). architecture as one of the most influential activities in the construction industry can play a significant role in increasing energy efficiency by switching to the use of renewable energies in buildings. using these sources of energies is the prerequisite for moving towards sustainable development (azizibabani, 2016). thus addressing the issue of sustainable development in the field of architecture is leading to develop sustainable architecture criteria. sustainable architecture is an architecture that seeks to minimize the negative environmental impact of buildings by enhancing efficiency and moderation in the use of materials, energy, and development space (sirija and arch, 2013). sustainable architecture is closely tied with the issue of reducing energy consumption and using renewable energies (sassi, 2006). some experts argued in this case that a large part of sustainable design is what we do through energy savings (edwards, 2001). although the principles of sustainable architecture include a wide range of applying the simplest methods to the newest sophisticated technologies (gorji, 2010), in order to move towards the goals of sustainable development, the compliance of the method with social and cultural backgrounds of environment’s users is also important (azizibabani, 2016). the challenge of sustainable architecture is associated with finding a comprehensive solution for environmental considerations and at the same time getting the right level of quality of life and preservation of cultural, economic, and social values (azizibabani, 2014). therefore, in this paper, after reviewing the concepts of sustainable development, the authors categorize movements related to sustainable architecture and evaluate the principles and strategies of each one in order to achieve the various dimensions of sustainability in architecture. in addition, by specifying the definition of a sustainable building and considering it as a theoretical framework of the research, they provide solutions to supply sustainable development goals in the field of construction and design stage. therefore, the authors began to introduce and evaluate building information modelling (bim) technique and its impact on achieving sustainability in the design process stage. in this context, sustainable buildings that the bim technique played an important role in their design process have been studied, and analyzed. the results show the importance of implementation of design and construction methods to gain sustainability in buildings so a comprehensive model to meet sustainable development goals in the field of architecture has been developed. the methodology of this research, which is conducted for practical use in the design process and to achieve sustainability in architectural design, is descriptive-analytic and is based on library information, and extracted data from case studies. the case studies have been mentioned in order to show the effects of design methods on the buildings sustainability. research questions are: _ how can an architect as one of the most influential people in the process of building design and consequently the construction industry, provide the necessary basis to put construction industry on the path towards sustainable development? _ what are the characteristics of a sustainable building that supply different dimensions of sustainable development goals? _ how can an architect improve the performance of buildings in order to meet sustainability goals in the early stages of design? sustainable development itself refers to “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (wced, 1987). although this concept was introduced almost thirty years ago, the subject is still current in today’s society. in this regard, principles and dimensions of sustainable development became clearer so that nowadays the concept of sustainable development is being checked in three areas of environthe concept of sustainable development 27 journal of sustainable architecture and civil engineering 2017/3/20 mental sustainability, economic sustainability and social sustainability (spaiser and ranganathan, 2016), which are as follows: _ environmental sustainability. an environmentally sustainable system must maintain a stable resource base, avoiding over-exploitation of renewable resource systems or environmental sink functions, and depleting non-renewable resources only to the extent that investment is made in adequate substitutes (morelli, 2011). in this sense, in addition to quantitative and physical development, quality development is also of particular importance. _ economic sustainability. the economic dimension of sustainable development is linked with economic growth and other economic parameters. “the well-being of the individual and the community must be maximized through the efficient use of natural resources and equitable distribution of benefits and energy efficiency” (zahrdi and jafari, 2006). _ social sustainability. “social sustainability is the main focus of the present and future generations (murphy, 2012). it aims to meet the needs, improve the quality of life, and use all the capabilities and competence in self-improvement (heerwagen and zagreus, 2005), and has the criteria such as equal access to resources (social justice), ability to live well, health and social welfare security, raising of awareness and education, participation, and promotion of public relations” (kefayati and moztarzadeh, 2015). as a result, the following definition of sustainable development, which has been referred to as different dimensions of sustainability, is considered a measure to assess the sustainability of buildings. “sustainable development is a process of change in which the exploitation of resources, the direction of investments, the orientation of technological development and institutional change are all in harmony and enhance both current and future potential to meet human needs and aspirations” (wced, 1987). in addition to the energy efficiency issue, which is associated with environmental side effects reduction (hui, 2001), addressing aspects of sustainable development in the field of architecture, caused by providing users comfort and maintaining social, cultural, and economic issues, was considered as a prerequisite for a sustainable design (azizibabani, 2016). this leads to the formulation of the definitions and components related to a kind of design, which is in line with the objectives of sustainable development that are known as sustainable design and the production of this kind of design in the field of architecture is sustainable architecture. the concept of sustainable architecture contains a wide range of definitions, techniques, and practices that multiple movements of different architectural approaches placed under this type of architecture. these movements can be divided into three general categories according to themes and approaches that have been adopted in the design. the first, which is related to the nineteenth century and the early decades of the twentieth century, considered architectural aesthetics topics and more concerned about harmony with the surrounding environment in terms of geometry and used materials. according to the terms of time, environmental pollution and energy issues have rarely been considered in this category. in this regard, we can mention the works of antonio gaudi as well as movements such as art nouveau. the use of renewable energy sources and natural resources conservation in other movements related to sustainable architecture, which are mostly related to the second half of the twentieth century, are of particular importance. there are two viewpoints in this regard. the first one is based on using new technologies in order to reduce energy consumption and exploit renewable energies (sinopoli, 2010). these strategies can include broad ranges of building intelligentization methods in order to reduce energy consumption and efficient use of natural lighting, the use of active systems for renewable energies production, rainwater storage systems, and grey wastewater reuse (clarke, 2008). the second viewpoint that is focused on using vernacular building materials and construction methods and passive heating and cooling systems in some cases totally rejects the technology. in the table 1 movements, related to the sustainable archisustainable development and architecture journal of sustainable architecture and civil engineering 2017/3/20 28 table 1 sustainable architecture movement (azizibabani, 2014) subject description main approaches figures o rg an ic a rc hi te ct ur e architectural movement in the late modern period that sullivan, frank lloyd wright, and álvaro aalto are the pioneers of it using natural models and systems holistic approach combine form and function o rg an ic a rc hi te ct ur e the exploitation phase were developed and have been mentioned in the table 2. however, in the field of design, building information modelling process and related applications, as a suitable context, can help designers and programmers assess the sustainability of design in the early stages of a project. therefore, we begin to explore the capabilities of this process in order to achieve sustainability in architectural design. it should be noted that in addition to environmental issues, considering the context of a project, cultural features, vernacular architecture, and economic issues play an important role in achieving sustainability objectives in architecture. subsequently the objectives of the sustainable architecture can be reviewed in three following dimensions: environmental objectives: creating superior environmental quality, waste removal, using recycled material economic objectives: creating superior values, reducing operation costs, inventing easy production approaches social objectives: safety, compliance, employing quality and healthy life in other words, in order to maintain sustainable development objectives in the field of architecture, the design must have the least environmental impacts, should be justified economically and must ensure the user’s personal and social health. subsequently sustainable buildings should pay respect to climate, humans, civilization, and environment. all three dimensions of sustainable development should be considered through its design and construction process (azizibabani, 2014). table 1. sustainable architecture movement (azizibabani, 2014) figures main approaches description subject o rg an ic a rc hi te ct ur e using natural models and systems holistic approach combine form and function architectural movement in the late modern period that sullivan, frank lloyd wright, and álvaro aalto are the pioneers of it organic architecture c lim at ic a rc hi te ct ur e design based on climatic typology impressionability of building form from climatic elements efficient use of climatic elements to provide comfort conditions in this movement design criteria are being extracted through climatic data analysis climatic architecture cl im at ic a rc hi te ct ur e in this movement design criteria are being extracted through climatic data analysis _ design based on climatic typology _ impressionability of building form from climatic elements _ efficient use of climatic elements to provide comfort conditions c lim at ic a rc hi te ct ur e the exploitation phase were developed and have been mentioned in the table 2. however, in the field of design, building information modelling process and related applications, as a suitable context, can help designers and programmers assess the sustainability of design in the early stages of a project. therefore, we begin to explore the capabilities of this process in order to achieve sustainability in architectural design. it should be noted that in addition to environmental issues, considering the context of a project, cultural features, vernacular architecture, and economic issues play an important role in achieving sustainability objectives in architecture. subsequently the objectives of the sustainable architecture can be reviewed in three following dimensions: environmental objectives: creating superior environmental quality, waste removal, using recycled material economic objectives: creating superior values, reducing operation costs, inventing easy production approaches social objectives: safety, compliance, employing quality and healthy life in other words, in order to maintain sustainable development objectives in the field of architecture, the design must have the least environmental impacts, should be justified economically and must ensure the user’s personal and social health. subsequently sustainable buildings should pay respect to climate, humans, civilization, and environment. all three dimensions of sustainable development should be considered through its design and construction process (azizibabani, 2014). table 1. sustainable architecture movement (azizibabani, 2014) figures main approaches description subject o rg an ic a rc hi te ct ur e using natural models and systems holistic approach combine form and function architectural movement in the late modern period that sullivan, frank lloyd wright, and álvaro aalto are the pioneers of it organic architecture c lim at ic a rc hi te ct ur e design based on climatic typology impressionability of building form from climatic elements efficient use of climatic elements to provide comfort conditions in this movement design criteria are being extracted through climatic data analysis climatic architecture l ow -t ec h a rc hi te ct ur e in this movement, the architects try to achieve sustainability without using technology and they try to rediscover traditional methods of construction _ minimal use of new technologies _ rediscovering traditional methods of construction _ minimizing construction costs l ow -t ec h a rc hi te ct ur e figures main approaches description subject l ow -t ec h a rc hi te ct ur e minimal use of new technologies rediscovering traditional methods of construction minimizing construction costs in this movement, the architects try to achieve sustainability without using technology and they try to rediscover traditional methods of construction low-tech architecture e co -t ec h a rc hi te ct ur e coordination of technology and nature to achieve sustainability this movement of architecture is against the high-tech movement due to the use of new technologies eco-tech architecture e co lo gi c a rc hi te ct ur e create harmony with nature efficient use of natural factors create minimal change in nature in this movement, architects consider all the aspects of environment, resources, local culture, economy, and source of materials in their design ecologic architecture table 2. principles, guidelines, and methods of sustainable development methods guidelines principles sustainable design energy conscious planning alternative source of energy passive heating and cooling systems energy conservation economy of resources reduce consumption trough indigenous landscaping and use of related equipment reuse trough rainwater and grey water collection water conservation material conservation design and construction proper sizing of building systems rehabilitation of existing structures and use of recycled materials material conservation use recycled and recyclable materials that can be extracted with minimum use of energy and environmental impacts pre-building phase life cycle design provide waste separation facilities use nontoxic materials to protect construction workers specify regular maintenance with nontoxic cleaners building phase e co -t ec h a rc hi te ct ur e this movement of architecture is against the hightech movement due to the use of new technologies _ coordination of technology and nature to achieve sustainability e co -t ec h a rc hi te ct ur e figures main approaches description subject l ow -t ec h a rc hi te ct ur e minimal use of new technologies rediscovering traditional methods of construction minimizing construction costs in this movement, the architects try to achieve sustainability without using technology and they try to rediscover traditional methods of construction low-tech architecture e co -t ec h a rc hi te ct ur e coordination of technology and nature to achieve sustainability this movement of architecture is against the high-tech movement due to the use of new technologies eco-tech architecture e co lo gi c a rc hi te ct ur e create harmony with nature efficient use of natural factors create minimal change in nature in this movement, architects consider all the aspects of environment, resources, local culture, economy, and source of materials in their design ecologic architecture table 2. principles, guidelines, and methods of sustainable development methods guidelines principles sustainable design energy conscious planning alternative source of energy passive heating and cooling systems energy conservation economy of resources reduce consumption trough indigenous landscaping and use of related equipment reuse trough rainwater and grey water collection water conservation material conservation design and construction proper sizing of building systems rehabilitation of existing structures and use of recycled materials material conservation use recycled and recyclable materials that can be extracted with minimum use of energy and environmental impacts pre-building phase life cycle design provide waste separation facilities use nontoxic materials to protect construction workers specify regular maintenance with nontoxic cleaners building phase e co lo gi c a rc hi te ct ur e in this movement, architects consider all the aspects of environment, resources, local culture, economy, and source of materials in their design _ create harmony with nature _ efficient use of natural factors _ create minimal change in nature e co lo gi c a rc hi te ct ur e figures main approaches description subject l ow -t ec h a rc hi te ct ur e minimal use of new technologies rediscovering traditional methods of construction minimizing construction costs in this movement, the architects try to achieve sustainability without using technology and they try to rediscover traditional methods of construction low-tech architecture e co -t ec h a rc hi te ct ur e coordination of technology and nature to achieve sustainability this movement of architecture is against the high-tech movement due to the use of new technologies eco-tech architecture e co lo gi c a rc hi te ct ur e create harmony with nature efficient use of natural factors create minimal change in nature in this movement, architects consider all the aspects of environment, resources, local culture, economy, and source of materials in their design ecologic architecture table 2. principles, guidelines, and methods of sustainable development methods guidelines principles sustainable design energy conscious planning alternative source of energy passive heating and cooling systems energy conservation economy of resources reduce consumption trough indigenous landscaping and use of related equipment reuse trough rainwater and grey water collection water conservation material conservation design and construction proper sizing of building systems rehabilitation of existing structures and use of recycled materials material conservation use recycled and recyclable materials that can be extracted with minimum use of energy and environmental impacts pre-building phase life cycle design provide waste separation facilities use nontoxic materials to protect construction workers specify regular maintenance with nontoxic cleaners building phase 29 journal of sustainable architecture and civil engineering 2017/3/20 tecture principles and approaches of each are provided. although approaches and design methods of various movements in the field of sustainable architecture are different, they follow the same principles that are saving resources, design based on life cycle and human design in order to move within the framework of these principles, tools, strategies and techniques both in construction and in the exploitation phase were developed and have been mentioned in the table 2. however, in the field of design, building information modelling process and related applications, as a suitable context, can help designers and programmers assess the sustainability of design in the early stages of a project. therefore, we begin to explore the capabilities of this process in order to achieve sustainability in architectural design. it should be noted that in addition to environmental issues, considering the context of a project, cultural features, vernacular architecture, and economic issues play an important role in achieving sustainability objectives in architecture. subsequently the objectives of the sustainable architecture can be reviewed in three following dimensions: s u st ai na bl e d es ig n principles guidelines methods economy of resources energy conservation _ energy conscious planning _ alternative source of energy _ passive heating and cooling systems water conservation _ reduce consumption trough indigenous landscaping and use of related equipment _ reuse trough rainwater and grey water collection material conservation _ material conservation design and construction _ proper sizing of building systems _ rehabilitation of existing structures and use of recycled materials life cycle design pre-building phase _ use recycled and recyclable materials that can be extracted with minimum use of energy and environmental impacts building phase _ provide waste separation facilities _ use nontoxic materials to protect construction workers _ specify regular maintenance with nontoxic cleaners postbuilding phase _ adapt existing structures to new users and programs _ reuse building components and materials _ reuse the land and existing infrastructures human design preservation of natural conditions _ understand the impact of design on nature _ respect topographical contours _ do not disturb the water table _ preserve existing flora and fauna urban design site planning _ avoid pollution contribution _ promote mixed use development _ create pedestrian pockets _ provide for human-powered transportation _ integrate design with public transportation design for human comfort _ provide thermal, visual, and acoustic comfort _ provide visual connection to exterior _ provide operable windows _ provide clean, fresh air _ accommodate persons with differing physical abilities _ use nontoxic materials table 2 principles, guidelines, and methods of sustainable development journal of sustainable architecture and civil engineering 2017/3/20 30 _ environmental objectives: creating superior environmental quality, waste removal, using recycled material _ economic objectives: creating superior values, reducing operation costs, inventing easy production approaches _ social objectives: safety, compliance, employing quality and healthy life in other words, in order to maintain sustainable development objectives in the field of architecture, the design must have the least environmental impacts, should be justified economically and must ensure the user’s personal and social health. subsequently sustainable buildings should pay respect to climate, humans, civilization, and environment. all three dimensions of sustainable development should be considered through its design and construction process (azizibabani, 2014). building information modeling and sustainable design building information modelling (bim) is the development and use of a multi-faceted computer software data model to not only document a building design, but to simulate the construction and operation of a new capital facility or a recapitalized (modernized) facility” ( ‎gsa, 2007). the result is a data-rich, object-based, intelligent, and parametric digital representation of the facility, from which views appropriate to various user’s needs, can be extracted and analyzed to generate feedback and improvement of the facility design ( ‎levy, 2012). bim is more than a device or design application because it is so effective in the design and documentation process. among the advantages of using bim in the design and construction process, the following items can be mentioned: _ the exercise of bim has led to enhanced productivity, abridged overhead costs, healthier time management, and superior customer-client affairs (sharma and gupta, 2016). _ the construction trade uses competent modelling to plan, design, organize, and manufacture modules of buildings. the planning and coordination using bim curtail flaws before execution (sharma and gupta, 2016). _ bim contributes time and expenditure savings and superior quality construction services. assorted bim tools can be used to put into practice the bim in construction projects (arayici and tah, 2008). _ design offers can be analyzed with great accuracy, simulations performed quickly, and the performance of the design can be assessed with confidence. all of these promote the capabilities and innovative solutions. _ environmental performance is more predictable and life cycle costs are better understood. _ according to the three-dimensional modelling, design is more understandable for employers and beneficiaries. _ digital product data can be exploited in downstream processes and used for manufacturing and assembly of structural systems (azhar et al., 2011). according to the capabilities that bim provides for designers at different stages of design, it can be considered as a proper device to achieve sustainability (fani, 2014). bim can be used in the following items: _ design based on topographic contours. _ investigating the effects of buildings and obstacles on the absorption of sunlight, wind speed, and wind direction in the early stages of design process. _ achieving optimal dimensions in the construction of spaces and equipment and choosing appropriate materials for construction of architectural spaces in order to save energy. _ analyzing energy consumption patterns in the building and taking necessary decisions in the early design stages. 31 journal of sustainable architecture and civil engineering 2017/3/20 _ evaluating the effects of climatic factors on the building volume by specifying factors such as the intensity of daylight, wind speed, etc., in the software database. in order to show the benefits of the bim based design process the following case studies, which contain sustainable buildings approved by leadership in energy and environmental design (leed) certification, have been surveyed. in all three projects bim based applications have been used to analyze the virtual model of the building from the early stages of the design process and the effects of these evaluations have been implemented in the final design. emory university psychology center (united states) this building, which has an area of 10200 squares meters, was devoted to research and educational use and succeeded in obtaining (leed) certification in the field of sustainable buildings. project cost totaled $ 35 million, was constructed in 16 months, and bim was used in order to investigate building sustainability during the different stages of design process. the results led to choosing the best options for building orientation, shell, fenestration, and efficient use of daylight (azhar et al., 2011). creating the project site bim model mitigated negative effects on the environment from a shading point of view (fig. 1). the changes in architectural design as a result of analcase studies fig. 1 investigating the effects of building shadow on the site and surrounding buildings (azhar et al., 2011) ysis performed on bim models have been mentioned in the following: _ reducing buildings openings in the west facade. _ reducing the area of the last floor in order to diminish shadow length. _ reducing height of the building. because all of the changes were made in the early design stages, the project design did not require additional time and cost. house in sonoma, california (united states) the building was completed in 2011 and all the buildings energy requirements have been met from renewable sources. a sloping roof provided the necessary space for establishment of photovoltaic panels and solar collectors. heat is provided through a radiant floor slab and heat pump powered by a roof-mounted solar array. in lieu of conventional air conditioning, summer air is drawn through an insulated, naturally cool plenum below the house and exhausted through clerestory windows and vents near the roof. the foundations were formed using insulated concrete forms (icfs) and the exterior walls fig. 2 investigation the amount of cut and fill through bim in order to choose the best choice (levy, 2012) journal of sustainable architecture and civil engineering 2017/3/20 32 were constructed using a structural insulated panel system (sips). this provided a tightly sealed and insulated shell and saved significant time and labor during framing. the exterior doors and windows are thermally broken aluminum with tinted dual glazing. other key features including a 20,000gallon rainwater harvesting system and semi-permeable driveway paving to minimize surface water run-off (levy, 2012). the bim was used in the following cases: _ site analysis to understand view lines and topography. _ 3d visualization for the client and the planning department. _ sun shadow and ventilation studies. _ preparation and verification of the sips shop drawings. _ using the bim model in the ecotect application in order to investigate function of natural ventilation in the building. _ calculating the volume of cut and fill in order to choose the proper option for building placement in the site. ross street house, madison, wisconsin (united states) the concept of this project was that of a carefully controlled light box, and bim (archicad) was extensively used in developing the home from its inception to the last stages of design. the form of the building was effected by passive solar design consideration. several sun studies informed the development of the brise-soleil on the southern elevation of the home and guided the form of the building. the fig. 3 location solar panels through bim site model (levy, 2012) louvers were designed to allow the sun to penetrate deep in to the space between october and february while shading the windows from may to august (levy, 2012). in order to achieve sustainability goals in the design, studies on bim models in determining the most appropriate place for the establishment of photovoltaic panels played an important role (fig. 3). in this regard, in order to minimize the shading on solar panels the bim model was evaluated in different periods during the year. as a result, these panels provided 58% of the energy requirements of the buildings. rainwater was collected in storage tanks or directly used for irrigation of the green spaces. the outer shell of the building was fully insulated, and the ventilation system used was proportional to the surface area and number of stories in the houses. the project met the goals of the program with a simple, well-considered and integrated design solution. the result was a comfortable, livable home with sunlight on the interior surfaces providing passive heating as well as visual excitement throughout the year. the home achieved leed platinum level certification. this was the first project to do so in the state of wisconsin (levy, 2012). results and discussion architectural measures to achieve sustainability can be classified into two main groups. the first one contains measures related to the construction field, which emphasizes using recycled or recyclable materials and renewable energy production active systems to minimize energy and resource consumption. these kinds of measures only support environmental and economic sustainability. the second group are related to the field of design. it is through the design stages that an architect can study the features of the context of the project and take necessary actions. these actions may be in response to the climatic and cultural features or the lifestyle of the users. some measures like investigating the best orientation for the building, designing passive ventilation systems and choosing the best placement for the active system’s equipment are so effective in order 33 journal of sustainable architecture and civil engineering 2017/3/20 to achieve environmental and economic sustainability and as mentioned it is recommended to use bim based design process to achieve the best results in this area. however, social sustainability can be achieved in architectural design through maintaining items like vernacular architecture features, user’s lifestyle patterns, human health and comfort and protecting physical resources. in the other words, the quality of design is the most important factor that can affect the social sustainability in architecture. according to the survey of sustainable development, sustainable architecture, and building information modelling concepts and obtained information from analysis of case studies, it was found that the concept of sustainable development shows the importance of addressing this issue in three areas of environmental, economic, and social. so a comprehensive pattern to put architectural activities on the path towards sustainable development has been proposed. in order to achieve sustainable architecture, all dimensions of sustainable development should be considered in the architectural activities and this is the main difference between sustainable architecture, and some concepts like green architecture or green building that only consider environmental sustainability. in addition to the advantages of using the above pattern in architectural activities, implementation of incentive policies by the relevant authorities in the form of tax credits for sustainable buildings can be a strong incentive to move towards sustainability. fig. 4 pattern to achieve sustainable development through architecture design and construction approaches regarding the use of renewable energies, natural ventilation and daylight from one side, and building intelligentization and the use of new technologies in order to reduce dependence on non-renewable energy sources on the other side, can directly affect the achievement of environmental sustainability in architecture. economic benefit and added value that can be achieved in the long term due to the lack of dependence on non-renewable resources in an architectural project, are the aspects of achieving economic sustainability in the field of architecture. considering civilization and vernacular architecture, maintaining the dynamism and vitality of the environment and designing spaces that are compatible with the culture, behaviors, and methods of human life are the aspects of social sustainability in the field of architecture. the bim based design process as a new technique to perform various analyzes on the design, can be useful in order to choose the best design alternatives from these points of view: climatic issues, materials and proper orientation, optimal sizes, heating and cooling systems according to user type, and climate and other issues affecting the sustainability plan. due to the documentation approach of the bim process in which all aspects of design (architectural, structural and mep conclusions journal of sustainable architecture and civil engineering 2017/3/20 34 installations) will be considered in a single model, the mismatch errors will be minimized and this will eliminate unforeseen costs in the construction process. subsequently, architectural design as one of the most effective activities in the field of construction can play an important role to move toward sustainable development, and bim as a powerful device can provide the necessary context to achieve sustainable design. references abel, c. sky high: vertical architecture. london: royal academy of arts; 2003. attmann, o. green architecture: advanced technologies and materials, new york: mcgraw hill; 2010 arayici, y., tah, j. towards building information modelling for existing structures. structural survey, 2008; 26:210-222. https://doi. org/10.1108/02630800810887108 azhar, s., hein, m., sketo, b. building information modelling (bim): benefits, risks and challenges. leadership and management in engineering, 2011; 11(3):241-252. https://doi.org/10.1061/(asce) lm.1943-5630.0000127 azizibabani, m. the role of building intelligentization in the process of moving towards sustainable development. second international conference on architecture, civil engineering and urban planning at the beginning of the third millennium. tehran; 2016. available at: http://www.civilica.com/paper-iacut02-iacut02_170.html azizibabani. m. binalood renewable energies research center. master’s thesis. islamic azad university of tehran; 2014. bauer, m., mösle, p., schwarz, m. green building – guidebook for sustainable architecture. berlin: springer; 2010. clarke, e. the truth about intelligent buildings. 2008 (accessed 9 may 2015). available at: http://www. climatechangecorp.com/content.asp?conten tid=5471 edwards, b. a. rough guide to sustainability. london: riba publications; 2001. elington, j. enter the triple bottom line. in henriques a., richardson j. (eds.) the triple bottom line, does it all add up? assessing the sustainability of business and csr london: earthscan publications ltd.; 2004; 1-16. fani, f. application of building information modelling (bim) in construction project management. the first congress of new technologies to achieve sustainable development, tehran; 2014. gorji, y. sustainable architecture and its critique in the field of environment. journal of the society of architecture and urbanism of iran, 2010; 15: 91-100. general services administration (gsa). bim guide series 01, 2007 (accessed april 2017). available at: www.gsa.gov/graphics/pbs/gsa_bim_guide_ v0_60_series01_overview_05_14_07.pdf heerwagen, j., zagreus, l. the human factors of sustainability: post occupancy evaluation of the phillip merrill environmental center, berkeley, ca. university of california center for the built environment; 2005. hui, s. c. low energy building design in high density urban cities. renewable energy, 2001; 627-640. https://doi.org/10.1016/s0960-1481(01)00049-0 kefayati, z., moztarzadeh, h. developing effective social sustainability indicators in architecture. bulletin of environment, pharmacology and life sciences, 2015; 40-56. levy, f. bim in mall-cale sustainable design. new jersey: john wiley and sons, inc.; 2012. morelli, j. a definition for environmental professionals. journal of environmental sustainability, 2011; 1(1): article 2. https://doi.org/10.14448/jes.01.0002 murphy, k. the social pillar of sustainable development: a literature review and framework for policy analysis. sustainability: science, practice & policy, 2012; 8(1):15-29. sassi, p. strategies for sustainable architecture. new york: taylor & francis; 2006. sharma, p., gupta, s. applicability of building information modelling (bim) in indian built environment sector. american journal of engineering and technology management, 2016; 1(3): 30-37. sinopoli, j. smart buildings system for architects, owners and builders. burlington (ma): elsevier, 2010. sirija, m., arch, b. necessity of sustainability in architectural practices for achieving sustainable development. international journal of science and technology, 2013; 2: 583-587. spaiser, v., ranganathan, s. the sustainable development oxymoron: quantifying and modelling the incompatibility of sustainable development goals. international journal of sustainable development & world ecology; 2016. https://doi.org/10.1080/1350 4509.2016.1235624 35 journal of sustainable architecture and civil engineering 2017/3/20 unesco. education sector. education for sustainable development. paris: united nations educational, scientific and cultural organization; 2012. world commission on environment and development (wced) (the brundtland commission) report, our common future. chapter 2: towards sustainable development. un documents: oxford university press; 1987. zahedi, sh., jafari, gh. expansion of the concept of sustainable development. journal of humanities teacher, 2006; 10(.4): 44-76. mohammadhossein azizibabani researcher housing foundation of islamic revolution deputy urban housing main research areas sustainable architecture, affordable housing design address housing foundation of islamic revolution tehran, iran tel: +98 21 88955901-10 e-mail: h.azizi66@hotmail.com marjan dehghani researcher housing foundation of islamic revolution deputy urban housing main research area affordable housing design address housing foundation of islamic revolution tehran, iran tel: +98 21 88955901-10 e-mail: h.azizi87@hotmail.com about the authors 75 journal of sustainable architecture and civil engineering 2017/3/20 introduction *corresponding author: volhasannikava@list.ru estimation of the restrained strains and self-stresses under two-way restraint conditions received 2017/09/18 accepted after revision 2017/11/21 journal of sustainable architecture and civil engineering vol. 3 / no. 20 / 2017 pp. 75-86 doi 10.5755/j01.sace.20.3.19082 © kaunas university of technology estimation of the restrained strains and self-stresses under two-way restraint conditions jsace 3/20 http://dx.doi.org/10.5755/j01.sace.20.3.19082 volha sannikava*, viktar tur brest state technical university, faculty of civil engineering moskovskaya 267, 224017, brest, republic of belarus models for the restrained expansion strains under two-way restraint conditions both with their advantages and disadvantages are presented. an implementation of the modified strains development model (msdm) for the assessment of the two-way restrained expansion strains is proposed. the reliability of the proposed model for the two-way restraint conditions is confirmed by the experimental results based on the tests of the expansive concrete plane specimens with the mesh reinforcement in the mid-depth of the cross section. keywords: design model, expansive concrete, restrained expansion strains, two-way restraint conditions. as was shown in semianiuk et al. 2017, the development of concrete technologies in the last decades has opened the door to extended use of the high performance concrete (hpc). shrinkage strains perform the most considerable problem of practical application of the high strength and high performance concretes because of inducing the cracks formation at early age that makes worse the serviceability performance of concrete structures. shrinkage processes are typical of any concrete system and depend on many factors such as type of cement, type of mineral admixtures, water-cement ratio and volume concentration of aggregate (tazawa et al. 2000). many studies have proved the effectiveness of the expansive concretes in the compensating of shrinkage (tanimura et al. 2007) as well as in realization of the chemical prestressing of the structures (mikhailov and litver 1974). 1974). in general, as was shown in semianiuk et al. 2017, models for the estimation of the restrained strains and self-stresses in expansive concrete at early age are based on one of two basic concepts: conservation law of chemical energy or initial strain calculation. to design self-stressed concrete structures it’s necessary to take into account the initial stressstrain state caused by the concrete expansion under restraint conditions. the dependence of restrained strains from the reinforcement arrangement (uniaxial, biaxial, triaxial), stiffness characteristics of restraint, curing conditions is confirmed by numerous investigations of self-stressed elements (litver and petukhov 1984, litver and sabajeva 1984, marchuk 2002, mikhailov and gershvald 1984, mikhailov and litver 1974,). it should be noticed that because of the features of the expansive concrete process under two-way restraint conditions the self-stressed concrete objournal of sustainable architecture and civil engineering 2017/3/20 76 tain more solid structure than that of under one-way restraint conditions. therefore the shrinkage strains become less apparent for the self-stressed elements under two-way restraint conditions. moreover these elements made with high expansion energy capacity concrete perform the extreme values of self-stressing in comparison with the element under uniaxial restraint (litver and sabajeva 1984). consequently, design model for the numerical determination of the restrained strains and self-stresses at the expansive stage of the concrete should be done in favour of that which could adequately reproduce chemical, physical and mechanical processes during the self-stressing concrete expansion under various design and technological factors. models of estimation the restrained expansion strains and self-stresses at the expansion stage of the concrete under two-way restraint conditions the following models for the evaluation of the restrained expansion strains in the reinforcement for elements under two-way restraint conditions have been suggested. model 1. in accordance with the tcp codes (2010), the strain in the center of gravity of reinforcement at the section by the time of the expansive concrete stabilization is expressed as: methods for estimation of the restrained strains and stresses in the expansive concrete at early age . . 0 1 s ce ce d s e w l s f k k k k k e ρ ε = ⋅ ⋅ ⋅ ⋅ ⋅ ρ ⋅ (1) 1, 57 0, 0057 l l kρ ⋅ρ = +ρ (2) where .ce df – design self-stress of the concrete that is taken from the table 6, 7 tcp codes (2010) depending on the self-stressing grade of the expansive concrete; lρ – total cross sectional reinforcement ratio; se – young’s modulus of the reinforcement; sk – factor that depends on the reinforcement arrangement in plane and equals 1,2 for the biaxial reinforcement arrangement in the concrete element; kρ – factor that depends on the total cross sectional reinforcement ratio for the given direction ( lρ ) and is defined as follows: ek – factor that represents the influence of the reinforcement eccentricity; wk – factor that counts the influence of the expansive concrete initial compressive strength at the beginning of moisture curing; 0k – factor that counts self-stressed element curing conditions at the expansion stage of the concrete. from this model it could be seen that two-way axial restraint conditions are considered only by the factor sk from the eq. (1). model 2. according to the experimental data obtained by marchuk (2002) the empirical expressions which consider the interference of the restraint in the principal axes directions on the restrained expansion strains are received: . . .0 . . .0 (0, 98 16 12 ) , (0, 98 16 12 ) , ce x ly lx ce x lx ly ce x lx ly ce x lx ly if if ε = + ⋅ρ − ⋅ρ ⋅ε ρ ≤ρ  ε = + ⋅ρ − ⋅ρ ⋅ε ρ >ρ (3) . . .0 . . .0 (0, 98 16 12 ) , (0, 98 16 12 ) , ce y lx ly ce y ly lx ce y ly lx ce y ly lx if if ε = + ⋅ρ − ⋅ρ ⋅ε ρ ≤ρ  ε = + ⋅ρ − ⋅ρ ⋅ε ρ >ρ (4) _ in the direction x _ in the direction y where . .0ce xε and . .0ce yε – restrained expansion strains of the expansive concrete in the direction x without considering the restraint in the direction y and otherwise in the direction y without considering the restraint in the direction x respectively: 77 journal of sustainable architecture and civil engineering 2017/3/20 1/ 2 , 1/ 2 , , , 1/ 2, 1/ 2 1 ( ) [( ) ( , )] ( ) i x i x c j i j x t as ds i j t j t t t t+ + ∆ + = ε = ∆σ ⋅ +ε∑ (8) .. . .0 . .0; ce d yce d x ce x ce y lx s ly s f kf k e e ρρ ⋅⋅ε = ε = ρ ⋅ ρ ⋅ (5) where lxρ and lyρ – reinforcement ratio in the directions x and y respectively; .ce df , se , kρ – as in the eq. (1). as seen from the above models 1 and 2, the components (0, 98 16 12 )lx ly+ ⋅ρ − ⋅ρ and (0, 98 16 12 )ly lx+ ⋅ρ − ⋅ρ from the eqs. (3) and (4) are, in fact, the refined values of the factor sk from the eq. (1). model 3. in the work litver and petukhov (1984) for the symmetrical reinforced plane self-stressed elements with the reinforcement ratio lρ the self-stress is defined in accordance with: . .20,702 0,0278 .2 . .2 ce df ce ce d lf − ⋅σ = ⋅ρ (6) where . .2ce df – the value of the self-stress which is defined in the dynamometrical rings with stiffness equals 1%lρ = . model 4. in the case of nonsymmetrical restraint in two directions in the paper mikhailov and gershvald (1984) the system of equations is used: 1/1/ . . . 1/ 1/ . . . (1 ) 0 (1 ) 0 nn ce x ce x ce y x n n ce y ce y ce x y a a b c c k a a b c c k     σ −λ − −λ − =    σ + σ +       σ  −λ − −λ − =    σ + σ +   (7) where .ce xσ and .ce yσ – self-stresses in the concrete in the direction x and y respectively; a, b, c – empirical coefficients; 210x lx sk e −= ρ ⋅ ⋅ , 210y ly sk e −= ρ ⋅ ⋅ – stiffness characteristics of restraint in the direction x and y respectively; λ – poisson’s ratio of the expansive concrete at early age that is accepted to be equal to 0,46..0,48 in accordance with mikhailov and gershvald (1984). it should be mentioned that all proposed design models of defining the stress-strain parameters of self-stressed elements under two-way restraint conditions have some significant disadvantages. first, all formulas contain either the empirical factors or expressions which are restricted by research conditions. second, no one formula counts the early age expansive concrete behavior as well as the contribution of elastic and plastic (creep) concrete strains on the restrained strains. as in the researches tsuji (1984) these models are based on the energy conservation law and allow to calculate the self-stresses or restrained expansion strains only by the end of the expansive concrete stabilization. it’s significant that at practical application of listed models some contradictions have been evolved (tcp code 2010) as they are being caused by different correlations of the free expansion strains and the standard self-stressing grade of the expansive concrete .ce df . model 5. a more advanced finite element method along with a practical calculation method based on the beam theory considers the mentioned disadvantages (ito et al. 2004). in accordance with this model for the self-stressed reinforced concrete elements in the case of the uniaxial reinforcement arrangement the strain in the x-direction at the i-th time interval is calculated by: where ,( )x c j∆σ – incremental self-stress in the x-direction at the j-th time interval; , , , 1/ 2, 1/ 2( )x t as ds it t∆ +ε – difference of the free strain due to the temperature change and shrinkage or expansion of the journal of sustainable architecture and civil engineering 2017/3/20 78 where s – empirical factor that takes into account cement type; a – empirical factor that takes into account initial setting time effect; ,28et – temperature adjusted concrete age at 28 days; t – temperature adjusted concrete age at t days. 0,5 ,28 ,28( ) exp 1 e c c t a e t e s t a   −    = ⋅ −   −    (10) the temperature adjusted concrete age at t days is determined by the equation (ito et al. 2004): where it∆ – number of days where a temperature ( )t c° prevails; ( )it t∆ – temperature in [ ]c° during the time period it∆ ; 0 1t c= ° . 1 0 4000 exp 13, 65 273 ( ) / n i i i t t t t t=   = ∆ ⋅ − + ∆  ∑ (11) the creep coefficient 0( , )t tϕ for the expansive concrete at early age is defined in accordance with fib model code (2010) by the equation: 0 0 0( , ) ( , )ct t t tϕ = ϕ ⋅β (12) ( )20 0 ,285, 31 ( ) 1 1,11c ce t eϕ = ⋅ − + (13) 0,3 0 0 0 ( , ) ( )c í t t t t t t  − β =  β + −  (14) where 0ϕ – notional creep coefficient that is estimated with regard to the relative young’s modulus 0 ,28( ) /c ce t e (the ratio of the young’s modulus of the expansive concrete at 0t to that of the expansive concrete at 28 days in the temperature adjusted concrete age) by the expression suggested in the paper ito et al. (2004): 0( , )c t tβ – coefficient to describe the development of creep with time after loading and it is calculated in accordance with fib model code (2010) by the equation: where t – temperature adjusted concrete age; 0t – temperature adjusted concrete age of loading age; íβ – coefficient representing the effect of loading age on the rate of creep development and it is defined with regard to the relative young’s modulus ,28( ) /c ce t e (the ratio of the young’s modulus of the expansive concrete at t to that of the expansive concrete at 28 days in the temperature adjusted concrete age) by the expression suggested in the paper ito et al. (2004): 1/ 2 1/ 2 ,28 ( , )1 ( , ) ( ) i j i j c j c t t j t t e t e + + ϕ = + (9) where ( )c je t – young’s modulus of the expansive concrete at jt days in temperature adjusted concrete age; ,28ce – young’s modulus of the expansive concrete at 28 days in temperature adjusted concrete age; 1/ 2( , )i jt t+ϕ – creep coefficient of the expansive concrete at 1/ 2it + days under constant self-stress applied at jt days. the young’s modulus of the expansive concrete at early age is calculated in accordance with the eurocode 2 model (2004): expansive concrete in the x-direction from the time interval 1/ 2t to the 1/ 2it + ; 1/ 2( , )i jj t t+ – creep compliance function which is defined by: ,28 ,28 ,28 0, 000001, 0 ( ) / 0, 346 ( ) 40, 5 0, 346 0, 485, 0, 346 ( ) / 1, 0 í c c c í c c c if e t e e t if e t e e β = ≤ <    β = ⋅ − + ≤ <      (15) 79 journal of sustainable architecture and civil engineering 2017/3/20 the difference of strain at i-th time interval and (i-1)-th time interval is obtained: 1 , 1/ 2 ( 1) 1/ 2 , 1/ 2 , , , , 1 ,28 ( , ) ( ) ( ) ( ) ( ) ( , ) ( ) ( ) i i j x c i x i x i x c i i i x c j x t as ds i j c t t t t j t t e − + − + + ∆ =  ∆ϕ ∆ε = ε −ε = ∆σ ⋅ + ∆σ ⋅ + ∆ε     ∑ 1 , 1/ 2 ( 1) 1/ 2 , 1/ 2 , , , , 1 ,28 ( , ) ( ) ( ) ( ) ( ) ( , ) ( ) ( ) i i j x c i x i x i x c i i i x c j x t as ds i j c t t t t j t t e − + − + + ∆ =  ∆ϕ ∆ε = ε −ε = ∆σ ⋅ + ∆σ ⋅ + ∆ε     ∑ (16) 1/ 2 ( 1) 1/ 2( , ) ( , ) ( , )i j i j i jt t t t t t+ − +∆ϕ = ϕ −ϕ (17) with: thus the incremental stress in the x-direction at the i-th time interval is calculated as follow: 1 , , , , , , 1 ,28 1/ 2 ,28 ( )( ) ( ) ( ) ( , ) ( ) ( ) 1 ( , ) i x c jc i x c i x c i i j x t as ds i c i j c i i c e t t t e t et t e − ∆ = +   ∆σ ∆σ = ∆ε − ⋅∆ϕ − ∆ε      + ⋅ϕ ∑ (18) where 1/ 2( , )i it t+ϕ – creep coefficient of the expansive concrete at 1/ 2it + days under constant selfstress applied at it days; , , ,( )x t as ds i∆∆ε – incremental free strain due to the temperature change and shrinkage or expansion of the expansive concrete in the x-direction at the i-th time interval; ( , )i jt t∆ϕ – incremental creep coefficient of the expansive concrete at the i-th time interval under constant self-stress applied at the j-th time interval. being the most rational today, the deformation model 5 can be used for the self-stressed reinforced concrete elements under arbitrary restrained conditions and allows to evaluate the stressstrain relationship of the self-stressed elements from the early age to the concrete expansion stabilization. if the free strain function and the incremental self-stress at (i-1)-th time interval are known, the incremental self-stresses and correspondingly the incremental restrained expansion strains at i-th time interval in the x-direction are calculated. however, the presented above model has got one important contradiction, what has been confirmed by own experimental data. as noticed in the researches tur and semianiuk (2016) and semianiuk et al. (2017) the expansion of the expansive concrete element at the elementary i-th time interval occurs in the presence of the cumulative force induced by the restraint at the end of the (i-1)-th time interval (fig. 1). fig. 1 scheme of the addition cumulative force action δpx.mt – cumulative force induced by the restraint in the x-direction; δlx.s – increment of restraint length in the x-direction caused by the concrete expansion; δlx.mt – increment of restraint length in the x-direction caused by the cumulative force; ac, ec – parameters of concrete section; as, es – parameters of restraint. thus, the main theses of the deformation model (model 5) modified by taking into account the additional cumulative force induced by the restraint have allowed to formulate the design model for self-stressed elements under two-way restraint conditions both for symmetrical and nonsymmetrical restraint in two directions. journal of sustainable architecture and civil engineering 2017/3/20 80 implementation of the msdm-model for the assessment of the two-way restrained strains the general theoretical background of the modified early age strains development model (msdm) for concrete with high expansion energy capacity in the case of the uniaxial reinforcement arrangement has been presented in the works tur and semianiuk (2016) and semianiuk et al. (2017). it should be noticed that because of the bond conditions the expansive concrete and the reinforcement deform compatibly: , , ,( ) ( )x c i x s i s x le∆σ = ∆ε ⋅ ⋅ρ (19) 1/ 2 , ,28 ( ) ( ) 1 ( , ) c i c i i i s x l c e t d e t t t e e + =   + ⋅ϕ ⋅ ⋅ρ     (21) in the present investigations, considering the additional cumulative force, the eq. (9) and the law of signs (expansive strains are taken with “plus”, shrinkage strains are taken with “minus”), the incremental restrained expansion strains in the x-direction at the i-th time interval are calculated as follows: 1 1 , , , , 1 1,28 ( 1) 1/ 2 ( , ) ( ) ( ) ( ) ( ) 1 ( ) i i i j s x s i cf i x c j x s j x l j jc c i t t ed d e e t − − = = − +   ∆ϕ ∆ε = ∆ε − ∆σ ⋅ − ∆ε ⋅ρ ⋅   +     ∑ ∑ (20) where ( )cf i∆ε – incremental free expansion strain at the i-th time interval; 1 , 1 ( ) i x s j j − = ∆ε∑ – resultant restrained expansion strains from the cumulative force at the end of (i-1)-th time interval of the concrete expansion; ( 1) 1/ 2( )c ie t − + – young’s modulus of the expansive concrete at the end of (i-1)-th time interval. the details of the eq. (10) are presented in the work tur et al. (2016). in the case of two-way restraint conditions the stresses in the principal axes directions are connected by means of poisson’s ratio ( µ ). there are two points of view concerning the poisson’s ratio of the early age concrete. some researchers (oluokun et al. 1991, truman et al. 1991) regard that one remains constant during expansion stage whereas others (mikhailov and gershvald 1984, byfors 1980, de schutter and taerwe 1996) have proved experimentally the evolution of the poisson’s ratio during the hydration. in the present study the poisson’s ratio of the early age concrete is taken 0, 47µ = according to mikhailov and gershvald (1984). thus, for the two-way restraint conditions the incremental restrained expansion strains at the i-th time interval in the principal axes directions are calculated by: 1 1 , , , , , 1 1,28 ( 1) 1/ 2 1 1 , , , , , 1 1,28 ( , ) ( ) ( ) ( ) ( ) 1 ( ) ( , ) ( ) ( ) ( ) ( ) 1 i i i j x s x s i cf i x c j x s j x l j jc c i i i i j y s y s i cf i y c j y s j y l j jc t t ed d e e t t t ed d e − − = = − + − − = =   ∆ϕ ∆ε = ∆ε − ∆σ ⋅ − ∆ε ⋅ρ ⋅   +       ∆ϕ ∆ε = ∆ε − ∆σ ⋅ − ∆ε ⋅ρ ⋅   +     ∑ ∑ ∑ ∑ ( 1) 1/ 2( )c ie t − +        (22) the incremental self-stresses at the i-th time interval in the principal axes directions are obtained as follows: ( ) ( ) ( )( ) ( ) ( ) ( )( ) , , , , , , , , , , , , x x s x s x l y s y s y li i i y y s y s y l x s x s x lii i e e e e  ∆σ = ∆ε ⋅ ⋅ρ −µ⋅ ∆ε ⋅ ⋅ρ  ∆σ = ∆ε ⋅ ⋅ρ −µ⋅ ∆ε ⋅ ⋅ρ (23) 81 journal of sustainable architecture and civil engineering 2017/3/20 the total self-stresses and restrained expansion strains in the principal axes directions at given time interval are defined by: ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) , , ,1 1 , , ,1 1 ; x x x x s x s x si i i i i i y y y y s y s y si i i i i i − − − −  σ = σ + ∆σ ε = ε + ∆ε    σ = σ + ∆σ ε = ε + ∆ε   (24) the iterative calculation continues until the end of the expansive concrete stabilization period. experimental investigations for the verification of the proposed model for the restrained expansion strains estimation at the expansion stage of the concrete under two-way restraint conditions the experimental investigations were conducted. the present investigations were carried out based on the three series of the expansive concrete plane specimens with the mesh reinforcement in the mid-depth of the cross section (fig. 2). the restraint rate in the principal axes directions was taken as the variable parameter of samples. series a b i 3ø12mm 3ø5mm ii 3ø12mm 3ø12mm iii 3ø5mm 3ø5mm 1 – expansive concrete, 2 – mesh reinforcement fig. 2 details of the experimental specimens geometry and reinforcement characteristics of the expansive concrete specimens are listed in the table 1. the view of the mold with mesh reinforcement and the specimen after casting is presented in the fig. 3. table 1 geometry and reinforcement characteristics of specimens series specimen marking specimen geometry, mm, bxlxh x-direction y-direction asx, mm 2 reinforcement ratio ρlx, % asy, mm 2 reinforcement ratio ρly, % i p1-1 p1-2 500x500x70 339 0,97 58,9 0,16 ii p2-1 p2-2 339 0,97 339 0,97 iii p3-1 58,9 0,16 58,9 0,16 asx– reinforcement area in the x-direction; asy– reinforcement area in the y-direction. journal of sustainable architecture and civil engineering 2017/3/20 82 the expansive cement was prepared in laboratory environment and consisted of the following components by weight: portland cement cem i 42,5r – 74%; high-alumina cement (hac) – 14%; gypsum – 12%. the expansive concrete mix composition per 1 m3 was as follows: expansive cement – 500kg; fine aggregate – 750kg; coarse aggregate – 1150kg; water – 215kg. the water-to-cement ratio (w/c) was 0,43. for every series of specimens the individual expansive concrete mix was prepared. the self-stressing grade of the expansive concrete was controlled in accordance with stb 2101 (2011). the free strains development of every series of specimens were measured on the prismatic samples bxh=50x50mm, l=200mm. the characteristics of the expansive concrete are listed in the table 2. after demolding at an expansive concrete age of one day, the specimens were cured up to 28 days under moisture conditions. fig. 3 the view of specimen before (a) and after (b) casting. a b table 2 characteristics of the expansive concrete series free strain at the concrete expansion stabilization cfε , % young’s modulus at 28 days age ,28cme , gpa self-stressing grade at the concrete expansion stabilization .ce df , mpa i 0,117 42,66 1,4 ii 0,437 23,1 2,4 iii 0,334 33,3 2,1 the restrained expansion strains and corresponding self-stresses experimental data of plane specimens in the principal axes directions from one day to the expansive concrete stabilization along with those calculated according to the proposed model and the model described in the work ito et al. (2004) are presented in the fig. 4-6. as could be seen from the fig. 4-6, providing the low restraint level equals ρl=0,16% the restrained expansion strains values calculated both according to the proposed model and design model ito et al. (2004) have the similar meaning during the whole period of the expansive concrete stabilization (series i, direction y; series iii, directions x and y). simultaneously, providing the high restraint level equals ρl=0,97% corresponding data have the similar meaning only within fourdays initial period of stabilization. but at the end of the expansion concrete stabilization period the divergence of calculated restrained strains values extends to 40% (series ii) and 26% (series i, diverification of the proposed model based on the experimental results 83 journal of sustainable architecture and civil engineering 2017/3/20 fig. 4 the restrained expansion strains and self-stresses in the principal axes directions for the series i fig. 5 the restrained expansion strains and self-stresses in the principal axes directions for the series ii rection x). at the same time in the case of nonsymmetrical restraint conditions in the direction with the low restraint level equals ρl=0,16% the self-stresses calculated both according to the proposed model and design model ito et al. (2004) have the divergence up to 40% (series i, direction y). this result is explained by the influence of the restraint in the perpendicular direction. comparing both experimental and calculated data of the restrained expansion strains and corresponding self-stresses it should be pointed out that values defined according to the proposed model have more similar meaning to corresponding experimental data over the whole expansive concrete stabilization period. as with the elements under uniaxial restraint conditions (semianiuk et al. 2017) in the case of twoway restraint conditions failing the addition cumulative force the wide disagreement has appeared journal of sustainable architecture and civil engineering 2017/3/20 84 fig. 6 the restrained expansion strains and self-stresses in the principal axes directions for the series iii between the experimental and calculated according to the model ito et al. (2004) restrained expansion strains and corresponding self-stresses values. this divergence has especially observed for series ii providing the high restraint level (ρl=0,97%) and high self-stressing grade of the expansive concrete ( .ce df =2,4 mpa). the comparison of the final restrained expansion strains values at the end of the expansion concrete stabilization period defined according to the available design models and corresponding experimental data for every series of plane specimens is shown in the table 3. table 3 the restrained expansion strains values of the plane specimens at the end of the expansive concrete stabilization calculated restrained expansion strains calc sε design model series i ρlx=0,97%, ρly=0,16% series ii ρlx=0,97%, ρly=0,97% series iii ρlx=0,16%, ρly=0,16% , calc s xε , ‰ , calc s yε , ‰ , calc s xε , ‰ , calc s yε , ‰ , calc s xε ,‰ , calc s yε ,‰ proposed model 0,794 1,054 2,166 2,166 3,050 3,050 model 1 (tcp codes 2010) 0,860 3,070 1,470 1,470 4,610 4,610 model 2 (marchuk 2002) 0,792 2,850 1,240 1,240 3,793 3,793 model 5 (ito et al. 2004) 1,071 1,160 3,662 3,662 3,284 3,284 experimental data expsε exp ,s xε , ‰ exp ,s yε , ‰ exp,s xε , ‰ exp ,s yε , ‰ exp ,s xε , ‰ exp ,s yε , ‰ p1-1 p1-2 p1-1 p1-2 p2-1 p2-2 p2-1 p2-2 p3-1 p3-1 0,872 0,978 1,161 1,146 2,058 2,589 2,327 2,381 3,132 2,731 design model exp calcs sε ε proposed model 1,098 1,230 1,101 1,087 0,950 1,195 1,074 1,099 1,027 0,895 model 1 (tcp codes 2010) 1,014 1,130 0,378 0,373 1,400 1,761 1,583 1,619 0,679 0,592 model 2 (marchuk 2002) 1,101 1,230 0,407 0,402 1,660 2,088 1,876 1,920 0,825 0,720 model 5 (ito et al. 2004) 0,814 0,913 1,000 0,987 0,562 0,707 0,635 0,650 0,953 0,831 85 journal of sustainable architecture and civil engineering 2017/3/20 as follows from the table 3 the restrained expansion strains values calculated according to the models 1 (tcp codes 2010) and 2 (marchuk 2002) differ considerably from the corresponding experimental data both towards overestimation (series i, iii) and underestimation (series ii). whereas the data of proposed model represent a good agreement with the corresponding experimental values (from 2,6% to 18,6 %). conclusions1 a design model for the restrained expansion strains defining under two-way restraint con-ditions is presented. this model is based on the modified early age strain development model (msdm) for the elements under uniaxial restraint conditions (tur and semianiuk 2016, semianiuk et al. 2017). 2 having a good agreement with the experimental data, the proposed design model is ad-equate enough for the restraint expansion strains estimation under two-way restraint conditions from the early age period to the expansion concrete stabilization. the experimental and calculated in accordance with the proposed model restrained expansion strains and corresponding self-stresses values have the similar meaning over the whole expansion concrete stabilization period (maximum divergence of values equals 22%). at the same time the comparison of the experimental restrained expansion strains values and those calculated according to the available design models (model 1 tcp codes (2010), model 2 marchuk (2002), model 5 ito et al. (2004), proposed model) demonstrates a good agreement of the proposed model data with the corresponding experimental data (maximum divergence of values equals 18,6%). 3 the main advantage of proposed design model is the consideration of the actual curing conditions of the expansive concrete specimens such as temperature, young’s modulus of the expansive concrete at given time interval and real free expansion strains development law of the expansive concrete from the early age to the end of stabilization period. 4 according to the proposed model the restrained expansion strains in the case of different reinforcement ratio in the principal axes directions might be estimated. byfors j. plane concrete at early ages. stockholm, 1980. cen, tc250, en 1992-1 eurocode 2: design of concrete structures – part 1-1: general rules and rules for buildings, 2004. doi: 978 0 580 73752 7. de schutter g., taerwe l. degree of hydration-based description of mechanical properties of early age concrete. materials and structures, july 1996; 29: 335-344. https://doi.org/10.1007/bf02486341 ito h., maruyama i., tanimura m., sato r. early age deformation and resultant induced stress in expansive high strength concrete. journal of advanced concrete technology, 2004; 2(2): 155-174. https:// doi.org/10.3151/jact.2.155 fib model code 2010, vol. 1, federal institute of technology lausanne – epfl, lausanne, march 2010. litver s., petukhov a. исследования и применение напрягающего бетона и самонапряженных конструкций [self-stress under biaxial restraint conditions] / сб. тр.: исследования и применение напрягающего бетона и самонапряженных конструкций, под науч. ред. в. в. михайлова. москва: ниижб; 1984: 67-78. litver s., sabajeva n. сравнительная оценка самонапряжения бетонов при однои двухосном ограничении деформаций расширения с учетом потерь от усадки [comparative appraisal of self-stress of concretes under uniaxial and biaxial restraint conditions with taking into account the shrinkage losses] / сб. тр.: исследования и применение напрягающего бетона и самонапряженных конструкций, под науч. ред. в. в. михайлова. москва: ниижб; 1984: 52-61. marchuk v. деформации и собственные напряжения несимметрично двухосно армированных плоских элементов из напрягающего бетона на стадии его расширения [self-stressing of selfstressed concrete structures in conditions for plane limitation of expansion strain]. дис. … канд. техн. наук, 05.23.01. брест; 2002. references journal of sustainable architecture and civil engineering 2017/3/20 86 mikhailov v., gershvald v. плоские самонапряженные конструкции [plate self-stressing structures] / сб. тр.: исследования и применение напрягающего бетона и самонапряженных конструкций, под науч. ред. в. в. михайлова. москва: ниижб; 1984: 62-67. mikhailov v., litver s. расширяющийся и напрягающие цементы и самонапряженные конструкции [expansive and self-stressing cements and selfstressed reinforces structures]. москва: стройиздат; 1974. oluokun f. a., burdette e. g., deatherage j. h. elastic moduli, poisson’s ratio and compressive strength relationships at early ages. aci material journal, jan.-feb. 1991: 3-10. semianiuk v., tur v., herrador m. f., paredes g. m. early age strain and self-stresses of expansive concrete members under uniaxial restraint conditions. construction and building materials, 2017; 131: 39-49. https://doi.org/10.1016/j.conbuildmat.2016.11.008 stb 2101-2010. бетоны напрягающие: технические условия [self-stressing concretes: specifications]. минск: руп “стройтехнорм”, 2011. tanimura m., sato r., hiramatsu v. serviceability performance evaluation of rc flexural members improved by using low-shrinkage high-strength concrete. journal of advanced concrete technology, 2007; 5(2): 140-160. https://doi.org/10.3151/jact.5.149 tazawa e., sato r., sakai e., miyazawa s. work of jci committee on autogenous shrinkage. international rilem workshop on shrinkage of concrete, 16-17 october 2000: 21-40. tcp 45-5.03-158-2009. бетонные и железобетонные конструкции из напрягающего бетона: правила проектирования [concrete and reinforced concrete structures from self-stressing concrete: design rules]. минск: минстройархитектуры; 2010. truman k. z., petrushka d. j., norman c. d. creep, shrinkage and thermal effects on mass concrete structures. journal of eng. mech., june 1991; 117(6): 1274-1288. https://doi.org/10.1061/(asce)07339399(1991)117:6(1274) tsuji y. methods of estimating chemical prestress and expansion distribution in expansive concrete subjected to uniaxial restraint. concrete library of jsce, 1984; 3: 131-143. tur v., kondratchik a., sannikava v. определение параметров напряженно-деформированного состояния плоских самонапряженных элементов на стадии твердения [the stress-strain parameters defining of plate self-stressed structures at curing period]. вестник бргту. сер. строительство и архитектура, 2016; 1(97): 70-76. tur v., semianiuk v. модель, применяемая для расчета связанных деформаций и самонапряжений в элементах из напрягающего бетона [models for restrained strains and self-stressing stresses in the members made of expansive concrete calculation]. вестник бргту. сер. строительство и архитектура, 2016; 1(97): 54-70. volha sannikava msc, engineer brest state technical university, faculty of civil engineering, department “geotechnics and transport communications” main research area self-stressing concrete structures address 267, moskovskaya str., 224017, brest, belarus tel. +375 29 7255952 e-mail: volhasannikava@list.ru victar tur professor, dsc, phd brest state technical university, faculty of civil engineering, department “technology of concrete and building materials” main research area self-stressing concrete structures, reliability of building structures address 267, moskovskaya str., 224017, brest, belarus tel. +375 33 6729404 e-mail: profturvic@gmail.com about the authors journal of sustainable architecture and civil engineering 2015/4/13 62 journal of sustainable architecture and civil engineering vol. 4 / no. 13 / 2015 pp. 62-69 doi 10.5755/j01.sace.13.4.13593 © kaunas university of technology received 2015/09/01 accepted after revision 2015/11/30 navigation on the neris river and its importance for vilnius jsace 4/13 navigation on the neris river and its importance for vilnius corresponding author: jurgis.vanagas@gmail.com http://dx.doi.org/10.5755/j01.sace.13.4.13593 jurgis vanagas department of urban design, vilnius gediminas technical university 26 pylimo street / 1 trakų street lt-01132, vilnius, lithuania neris is the second longest river in lithuania, flowing over the territory of vilnius, the capital of lithuania. it played an important role in the history of vilnius, particularly, as a waterway, which, in the past, connected the grand principality of lithuania (gpl) with the neighbouring regions and countries. the river and its tributary, vilnia, played the main role in the economic development of the city, as well as the development of the industry based on water-driven mechanisms, fishing and other riverside trades, recreational activities of the inhabitants and the urban infrastructure of vilnius. the role of the river, which decreased in the second half of the 19th century because of the development of land (railway and automobile) transport, became negligible in the years of the soviet power (1945-1990). it happened due to the drop of water elevation caused by the intense drainage of the areas and, particularly, the barbarous construction of a dam at the riverhead in byelaruss in 1974, which fenced off a large area of the vileyka reservoir. moreover, the works for deepening the riverbed by removing stones and shoals were stopped, and it made the river unnavigable. the paper also describes frequent floods caused by the drifting of ice in the spring, which brought great damage to the city in the past, as well as the types of ships and rafts used for navigation. keywords: river neris, etymology of its name, navigation, types of ships, rafts, floods. water transport is the cheapest and the oldest mode of transport.. it operates on a natural track and hence does not require huge capital investment in the construction and maintenance of its track. the cost of operation of water transport is also very less, it has the largest carrying capacity and is the most suitable for carrying bulky goods over long distances. that is why water transport was not only indispensable to foreign trade but had played a very significant role in bringing different parts of europe closer as well. in lithuania like in other european countries inland water transport had been used for centuries and was very important to the development of local economy. there are 600 kilometres (370 mi) of natural waterways perennially navigable. the main lithuanian river nemunas all the time was suitable for big barges, as second river neris (vilija) before the war was chiefly used only for small boats and raft transport for navigation between kaunas and jonava (40 kilometres), as well as between vilnius and nemenčinė (32 kilometres). navigation had been undertaken with a view to regularising the riverbed especially by removing the rapids. the vessels engaged in its navigation were of 5 to 8 tons and used for carrying passengers as well as for agricultural produce and merchandise. introduction 63 journal of sustainable architecture and civil engineering 2015/4/13 river neris and its ford (“brasta”) near the castle of the ancient lithuania`s capital was widely known as an important place through which numerous land ways linking southern and northern part of lithuania had been passed. unfortunately, nowadays the role of lithuanian inland waterways in the overall transport system is limited. this is because of a number of reasons including: shoals, seasonal change in water level, limited number of navigation routes, obsolete fleet of inland water vessels not adjusted to carry different types of cargo and passengers, and lack of modern infrastructure. in the architectural point of view vilnius, which territories are situated on the both sides of the river, is rather rare city in the world which doesn`t take advantages of these favourable natural conditions. fortunately, according to the future vision of city there are number of long-term plans to use more intensively the favourable functional and compositional resources of neris and thus to resume some of old historical traditions. the method used in this paper was based on compiling the historical facts, while the events described were taken from the sources, including numerous state and municipal archives. old vilnius newspapers published at the end of the 18th century, as well as in the 19th century and later, were also studied. the author looked through the documents stored in the municipal archive, which deal with the navigation on the neris river, its use for the town’s needs. the plans for using the neris river on a much wider scale and the perspectives of the suggested measures, as well as the attempts made to turn the city’s “face” towards the river and more intense development of the “water front” architecture were described based on studying recent information in the mass media. method the name of the river and its navigational characteristics though the origin of the river name, neris, has been explained differently, this name has much in common with the name of lithuanian capital, vilnius. according to the work of jan dlugosz1, a polish historian, ‘<…>vilnius, the current capital of lithuania, was named after duke vilius, under whose leadership many people left italy and roamed over different countries. similar names (vilija and vilnia) were given to the rivers, flowing through the vilnius territory’ (dlugosz, 1868). in another source, an old polish geographic reference book (słownik geograficzny 1893), the origin of the name vilija is referred to a belarusian word ‘вилать’, which means‘to twist’, ‘to wind’ or‘to change direction’.however, linguists believe that the names of both rivers are baltic and derive from the verbs nerti (to dive) and vilnyti (to wind or twist). in the book of count konstantinas tiškevičius, ‘neris and its banks’, describing his impressions about the voyage down the neris rriver, which was published posthumously by jozef kraszewski in dresden in 1871, it is written that vytautas the great, in his letter to crusaders in 1398, called the river nerige. in this book, he mentioned that the river was called so in 1390 in the deed of jogaila, by which the king transferred paneriai district to vilnius cathedral chapter. in particular, he wrote: ‘<…>obstaculum in superiori parte nostri obstaculi in fluvio vigilia situati’. this way, jogaila wanted to perpetuate the memory of lithuania’s christianization. in the middle of the 19th century, k. tiškevičius recorded a legend, saying that, in the old times, a tailor, whose name was steponas, had been turned to a stone, and his wife ulijona had been crying so hard that a spring had formed from her tears, which people called vuliana, vilijana and, finally, vilija. 1 jan dlugosz (1415–1480) was a nobleman of wieniawa coat of arms, a polish historiographer, a diplomat, a canon at krakow and a chronologist. he wrote much about the history of lithuania and was one of the first researchers who announced that lithuanians were of roman origin. along with providing valuable objective data, he also demonstrated onesided, tendentious views on the policy of the grand duchy of lithuania. journal of sustainable architecture and civil engineering 2015/4/13 64 as mentioned above, there were some attempts to trace the origin of the river to a belarusian word vilat’ (i.e. to wind or often change direction)2. the neris is the largest tributary of the nemunas river and the second longest lithuanian river, having the length of 510 km. a section of this river of 275 km is on the territory of belarus, while the remaining section of 235 km is in lithuania. the basin area is about 25 thou. km2, with the area of 14 thou. km2 belonging to lithuania. not so long ago, the neris was much more full-flowing3 and, therefore, played a very important role in the trade of vilnius with other countries, particularly, with slavic lands because it was the main mover of the state’s development. the plan of vilnius drawn in 1790 by a prussian officer shows that neris was abundant in water near vilnius and had the width of 80-100 steps and the depth of 8–10 feet. this was sufficient for navigation even during droughts. in the russian study of rivers and navigation, it was mentioned that the draught of a freighter with the tonnage of 2000–8000 poods4 did not exceed 3–4 feet. the level of water in the neris had dropped considerably in the soviet period due to the drainage (reclamation) of the swamped lands at the riverhead. besides, it should be noted that a12 m high dam built in 1974 in belarus near vileyka, at a distance of 406 km from the mouth of the neris river, also greatly contributed to its drying up (kudaba 1985). an artificial pond of 73 thou. hectares, which was twice as large as kaunas reservoir, was also made (žemulis 2014). it caused the decrease in the river’s flow rate near vilnius by more than 10 percent. an artificial pond could also have been made near vilnius. thus, in 1938, the construction of the first hydroelectric power station was started on the neris near turniškės. according to the plan, the water level had to be 11.6 m, the reservoir area – 5.6 km2 and its volume – 27 mill. km3. when lithuania regained the vilnius region, the work was continued by the joint-stock company ‘elektra’. the base of the dam was being constructed, a narrow gauge railway line, as well as a road, were built and the electric power lines were set up. the construction work was suspended because of the war to be never resumed in the post-war years (kilkus 2011). in2 the past,3both4 the upper and the lower reaches of the neris were navigable. it is known that, in the 17th-19th centuries, about 60-80 ships arrived at vilnius or sailed by it every day. the ships sailed not only to kaunas. in the ‘sarmatiae europeae description’ chronicle (1570), alessandro guagnini (1535–1614) wrote that the neris was a river with intense navigation, which was used by the residents of vilnius for transporting goods even to danzig (as mentioned in the ‘german chronicle’5). it is also well known that the merchants from vilnius and other places transported their goods in this way in 1380, 1444, 1494, 1535 and other years. the ships also carried cannons from vilnius to klaipėda (šėmienė 1994) because vilnius was famous for its cannon foundry (‘puškarnia’). 2 the author of this book believes that it is necessary to clarify the situation and keep to the opinion of vykintas vaitkevičius about the considered problem, which he had thoroughly analysed and expressed as follows: ‘the problem associated with the river names, vilija–neris, which has been in the centre of discussion for many years, should not be solved only in terms of ethnolinguistics’. the level of knowledge of this region’s history allows us to put forward a hypothesis that 1) the name vilija (velija, velja or vilja) is the only historical name of the upper reaches of this river (up to the 141st km); 2) the eastern balts (lithuanians), who used the neris name, referred it to the river section from the junction of vilija and naroch; 3) in the 11th12th centuries, the name of vilija (velija, velja or vilja) emerged due to the expansion of east slavs or the domination of the ruthenian language in the gdl internal office in the 15th and 16th centuries. later, when the polish language had become dominant in this region, neris was called only by the name of vilija (vilja, velja) (vaitkevičius 2005). 3 the plan of vilnius (1808) demonstrated that four rivers flowed into the neris river in the area, stretching from the middle of the present antakalnis street to the former slushko palace. however, in 1845, as many as five small rivers, flowing into the neris from viršupis to the same place, were shown in the plan. historians have found a record in the lithuanian metrica that the sixth small river, giraitė, flowed in the antakalnis district.however, its location has not been found (jurkštas 1990). 4 pood is an old russian unit of weight equal to 16 kg. 5 german chronicle by johannes friedrich rivius (1500–1553). navigation in the past 65 journal of sustainable architecture and civil engineering 2015/4/13 k. tiškevičius wrote that, in 1390 samogitians, through the mediation of vytautas, had made a trade agreement with karaliaučius (kaliningrad) and since that time crusaders had stopped hampering their trade (the exchange of goods). the most active traders were from jurbarkas, ragainė and klaipėda. in 1404, lithuanians started shipping wood, grain, seeds, flax, hemp fibres and other products down the river to gdansk and, in return, got clothes, sugar, salt, herrings and iron. there were heaps of logs for rafts on the neris banks down from the antakalnis district (tyszkiewicz 1871). during the 15th-17th centuries, there was a landing for merchant ships on the riverside of lukiškės, which was surrounded by wooden barns with stone foundations for storing goods. this suburb also had a lot of large wooden barns for rafts and logs floated to vilnius down the neris river and dragged out on the riverbank not only in lukiškės, but also in antakalnis and other places. on november 26, 1492, in trakai, alexander, the grand duke of lithuania, granted the city merchants the right of having stores and free trade along the banks of the neris river on its route up to kaunas. he also once again granted magdeburg rights to vilnius. this meant that foreign merchants were prohibited to sell their goods in lithuanian towns and cities without magdeburg rights. when passing vilnius, they had to stop there, and if there were merchants who would like to buy their goods, these merchants had the priority of buying the delivered goods. the names of the following old ships and rafts can be found in the historical documents:vytinės, strugai, laibos, dėžės, pergos, batai, skultai, kamegos, etc.(little lithuanian encyclopedia 1968). note that these lithuanian names are given in their original form because it is hardly to find their exact english equivalents, but their definitions will be provided below. there are no detailed pictures ant descriptions of these ships (boats)and rafts. vytinės as water facilities are the best known ships. they are followed by strugai6. according to r. adomaitis, a historian, the head of the navigation history department of the lithuanian sea museum, vytinė was the main type of local merchant ships which was unique and used only in lithuania in the period from the 15th to the end of the 19th century. vytinės carried wood and grain even to gdansk (vytinė 2013). its etymology as an original lithuanian word confirms that it refers to a historical lithuanian ship. such words as vytininkas (river transport worker), vairas (rudder), irklas (oar), kartis (punt pole) and laivavirvė (ship rope) emerged together with this word in lithuanian vocabulary. it is believed that the word vytinė also defines the construction of the ship, the bent frames7 (špantai) of which resembled flexible willow withes (vytelės). it also applies to the old ships described by k. būga, which sailed lithuanian lakes and rivers. their hulls were weaved from withesand covered with leather (vytinė 2013). k. tiškevičius wrote that vytinės mainly sailed on the nemunas because the neris river was dangerous (there were many shoals8 and lots of large stones in it), and only light strugai could sail there (tyszkiewicz 1871). later, researchers have shown that tiškevičius was wrong, and vytinės also sailed on the neris river in the 16th-18th centuries (ragauskas 2012). some data were provided by historian j. jurkštas, who wrote about the old vilnius waterways. according to him, vytinė was a large, 65 m long, 5-6 m wide and 1.8 m high flat-bottomed ship with one straight sail and pointed nose and back end. it could carry the cargo of about 300 tonnes. in the 17th century 6 strugas (струг in russian) is a flat-bottomed river or lake boat propelled by oars or sails which was used in russia in 11th-18th centuries for carrying people and cargo. it was usually 20-45 m long and 4-10 m wide. after delivering goods to riga and karaliaučius and their unloading, the ship used to be sold for firewood. otherwise, a team twice, as large as the initial one, would be required to pull the boat upstream by the rope tied to the top of the mast (samalavičius 2012). when armed with guns, strugas could be used for military operations. 7 frames (špantai) denote the cross beams of the boat body, to which its walls are fixed. 8 shoal (rėva) is a sandbank visible at low water and consisting of sand, silt and/or pebbles. what ships were sailing the neris river in the past? journal of sustainable architecture and civil engineering 2015/4/13 66 vytinė cost 600 grosze (jurkštas 1990). the direction of its sailing was regulated by a long oar like that used on sieliai (rafts) rather than by an ordinary rudder. the team consisted of several people. the ship even had a masonry stove for baking bread because the voyage to the sea took several weeks (vytinė 2013). the ship-building centre was in kaunas, but the ships of the above type were also built in vilnius in the 19th century. there is a hypothesis that the suburb of kaunas, vičiūnai, fig. 1 one of the numerous stones in neris river which is situated on the nemunas, bears a relation to vytinės (vanagas 2008). from the perspective of navigation, the neris river had always been very ‘capricious’ because there were many dangerous shoals and large stones9 in it. therefore, the river required cleaning. there are some documents proving that vilnius residents paid for cleaning the river in 1589. the work was repeated in 1606, but that time the government covered the expenses. this is a record from the diary of a german diplomat konrad von kyburg (though some historians doubt its authenticity): ‘in the afternoon of june 30, 1397, we took beautiful ships and started sailing on the neris river to kaunas, where we arrived on the 3rd of july. we could be there much earlier because the ships were very light and the current was swift, but we were afraid to sail at night and dash against underwater stones or fishers’ nets (barriers), which were plenty in the river. therefore, we sailed only in the daytime’ (kибург 1868). prospects of shipping: utopia and reality the rulers of the grand duchy of lithuania were not satisfied with the state of shipping on the neris river. they had very ambitious plans of greatly expanding the trade links of vilnius with other countries by waterways. count k. tiškevičius in his book (tyszkiewicz 2012) mentioned the idea of connecting the baltic sea with the black sea by digging a canal between the neris and the berezina rivers. this idea arose in the time of the rule of žygimantas augustas, but was turned into a vision by žygimantas iii. the ruler’s son, vladislovas, even wanted to finance the digging of this canal. in 1631, the plan of laying the way from one sea to another was discussed in the warsaw sejm, and a special commission was set up for determining if the project could be profitable, as well as for examining the territory, on which the canal had to be dug. nobody knows why the project failed910. could one ever imagine a recreational voyage from vilnius (the antakalnis pier) to odessa? however, it was not an idle fancy for kaunas because a 2500 km water route from the curonian lagoon (kuršių marios) to the black sea really existed! on the initiative of the grand hetman of lithuania 9 the river transport workers, rafters, sailors and fishermen even gave the nicknames to these large stones, such as avinas (ram), dvylas (reddish brown), ‘dziuravyj kamen’ (holed stone), jautis (bull), karvutė (cow), kunigas (priest), tilvikas (sandpiper), ‘trys broliai’ (three brothers), etc., which reflected their vivid imagination and sense of humour. 10 however,it is true that the russian government had appropriated this idea, and having changed the route, dug the berezina canal (in the period from 1797 to 1804). in the beginning, only timber was rafted by this route, but, in 1805-1817, middle-sized freight ships with grain and salt were sailing on the canal. during the period of 1817-1843, the shipping on the canal came to a standstill. in 1843, the bed of the canal was cleaned, the locks changed their places, and other obstacles were removed. this allowed the authorities to renew shipping on the canal. however, soon it became clear that it was unprofitable. at the turn of the 20th century, a plan of digging two canals (one for the internal trade, another for military purposes) in this area was worked out in russia. they planned to sail their warships if the war broke ou ton the second canal, which would connect the baltic sea and the black sea. unfortunately, the idea of connecting the capital of lithuania to the ports of the black sea has never been realized. 67 journal of sustainable architecture and civil engineering 2015/4/13 and vilnius military commander, mykolas kazimieras oginskis11 and using his personal funds (12 million złoty), the digging of 54 km long canal (the oginski canal), connecting the shchara, a tributary of the nemunas, and the jaselda, a tributary of the pripyat in the dnieper basin, was completed in the period from 1765 to 1784. in 1784, the first ship carrying 35 ‘laszts’ (1 laszt is equal to about 2 tonnes) of barley (i.e. about 70 tonnes of grain), came to karaliaučius from kherson via nemunas (pawłowski 1911). otherwise, it would have required sailing around the whole europe to get there! the oginski canal was used for floating rafts and logs, as well as for transporting grain, salt and potash. in 1905, 3.5 million poods of cargo were transported via the canal between the river basins of the nemunas and the dnieper. however, the importance of this canal has decreased with time. finally, it was abandoned and its locks failed.(pawłowski 1911). many long rafts, resembling long trains, sailed to vilnius via the neris. it was fascinating to watch the two rafters at the ends of the raft, skilfully steering a long, heavy and unwieldy raft at the sharp bends of the swift river by manipulating long heavy oars fixed to it. the rafts were moored to the left bank in antakalnis or to the right bank near the sawmill, below the green bridge and opposite the st jacob church. the rafts and logs were pulled from the water mainly in lukiškės and antakalnis, where the bank was dry and gently sloping. a tax had to be paid for piling them on the bank (on the photograph made by a. čechavičius in 1873 we can see the piles of logs on the river bank and upstream, near the slushko palace). the rafts were floating down the neris river almost until the middle of the 20th century. from the upper reaches of the neris they sailed to kaunas and, from there, to klaipėda. then, timber was transported by ships to great britain and germany. the logs of the trees cut on the banks at the riverhead and wound with young birches or linden basts (later, with wire) were tied to make 10 m wide and up to 80 m long rafts. this was a difficult work requiring great skill. logs, reaching 10 m in length, were sorted. heavier logs were placed between the lighter conifer tree logs. then, 12-13 logs were tied up to make the so-called ‘lavkas’, several of which formed rafts.the first ‘lavka’ known as ‘galva’ (head) had to be tied very fast. the gaps between the first three ‘lavkas’were usually wider than others, which helped the rafters better control the raft at the sharp bends of the river. at the front of the first ‘lavka’ and at the rafts fig. 2 rafts in the centre of vilnius (photo by j. čechavičius) end of the last one, 6 m long pinetree oars or rudders called ‘apačinas’ were firmly attached to the stamp of a forked tree11. usually, at the first end, there was a highly experienced rafter, who had to have good knowledge of the fairway, i.e. the insidious neris river with lots of protruding stones and banks. in the strong current, the rafters usually halted the rafts by inserting a 5 m long cudgel (‘šaryga’),reaching the river-bed, into the gap between the logs. on the bank, the rafts were tied with ropes to stakes driven into the ground (‘hartoliai’). the last ‘lavka’ of the raft (known as ‘zadnik’)was coated with moss and used as a campfire for cooking or asa tent for sleeping at night, which was made of branches and covered with straw. 11 mykolas kazimierasoginskis was taking care of his relative mykolas kleopas oginskis (1765-1833), a famous composer, the author of polonaises and mazurkas, for many years. in 1766, he bought the slushko palace in antakalnis. fig. 3 neris river near the st. raphal church journal of sustainable architecture and civil engineering 2015/4/13 68 the work of rafters was difficult. the neris got narrower between vilnius and kernavė. therefore, rafts had to be also made 3-4 m narrower. the rafts floated from žeimena to valakampiai had to be widened. the voyage down the river to kaunas took almost a week. the rafters usually floated several rafts simultaneously. this allowed them to help each other because sometimes rafts got stuck or were wrecked. in vilkija, below kaunas, rafts had to be tied up again to obtain large ‘cruiser’ type rafts of about 120 m in length. at the mouth of the nemunas or in klaipėda, rafters left the floated rafts, which were usually bought by jews, and went backon foot or by a passing transport facility. the landings for passenger ships on the neris had always been arranged near the road, leading along the river bank from town to antakalnis. ships usually got to verkiai or even to nemenčinė from there. however, sailing down the river was complicated because of many whirlpools, rapids and underwater stones on the way. near the landing there was a boat station with boats for crossing the river. boats with raised bows, having longitudinal stripes of various colours painted on their sides, took 5-6 people at a time across the river to its right bank, where the former piromontas country estates were situated. the rower of such a boat used only one long oar, also painted in a particular colour. on the left bank of the river, just past the bridge over the vilnia, there were several boat clubs, the most famous of which was azs (akademiczny zespół sportowy). there, the residents of vilnius could rent a kayak and row upstream the swift river. the area with a concrete surface has remained since that time at this place. there were also several approaches to the neris then. the city duma pointed out their locations in 1881 and defined the places, where pumping stations had to be built because water was used not only for fighting a fire, but also for various everyday needs. when did steamboats appear on the neris river? the first steamboat in the world was built in 1807 by an american, robert fulton, and after 30 years the english steamship ‘sirius’ already crossed the atlantic ocean. in vilnius, the first steamboat with a steam engine of only 10 hp, named ‘vilnius’ (‘wilno’), appeared in 1867. it was launched in 1850 in the rhine ship-building yard and floated to vilnius. having reached karaliaučius, it stopped there to pass the winter. the steamboat finally arrived in vilnius on may 13, 1856 and was moored to the pier near the lukiškės square. the next day (on wednesday), followed by loud applause of vilnius residents, the steamboat began its maiden voyage to verkiai. unfortunately, the condition of the riverbed at that time and too shallow water near the ferry landings did not allow it to continue the voyage on the neris. the steamer returned to the nemunas, sailed to the riverhead and during the summer of 1856 was travelling from gardinas (grodno) to druskininkai. however, historian adomas kirkoras gave a different description of shipping on the neris and the conversion of vilnius into a river port. according to him, in 1855, duke reinoldastyzenhauzas bought two steamers. the larger one named ‘kęstutis’ was intended for sailing on the nemunas, while another steamer called ‘neris’ was left to sail on the river of the same name. ‘neris’ began its voyages in the spring of 1856 from one of the first landings after vilnius–sosenka and was sailing for the whole summer from vilnius to kaunas, also carrying passengers from vilnius to verkiai. unfortunately, navigation on the neris lasted only for one season because in kaunas blocks of ice made holes in the sides of the steamboat. therefore, ‘neris’ has never returned to vilnius. the steamboat ‘kęstutis’ was sailing on the nemunas for a long time (kirkor 1882). it is worth noting that the first shipping centre in the nemunas river basin, water transport board, was established in gardinas. in 1914, a river port was built here. besides, a foreign businessman, o’brien de lacy, created a ship-building yard not far from there, in pinsk. later, it was expanded and transferred to gardinas. some of the first new ships were launched and the old ones were repaired there. they were given fine lithuanian names, such as‘birutė’, ‘bajorė’, (‘bojarinia’), ‘dievaitis’ (‘dewaitis’), ‘kęstutis’ (‘kiejstut’), etc.in the 20th century, a real steamship boom has begun12. 12 it is sufficient to note that before the world war ii, 31 passenger ships were moored in the kaunas river port. they carried holidaymakers, as well as the residents of large and small towns situated on the nemunas, including craftsmen, merchants and farmers. passenger ships on the neris river 69 journal of sustainable architecture and civil engineering 2015/4/13 at the beginning of the 20th century, there were two passenger shipping routes in vilnius. one of them began at the centre of the main port and led to the present the wroblewski library of the lithuanian academy of sciences and, further, to verkiai (with landings on the testing ground in šiaurės miestelis (northtown), kalvarija and valakupiai). another route led to nemenčinė, a famous health resort area at that time, visited by many russian high-rank officials and rich fig. 4 the first steam ship in the river neris jewish holiday-makers. three steamboats called ‘gardinas’, ‘žvaigždė’ and ‘kronprincesė’ carried them there. on the short route, the ships made 12 voyages a day. the first-class ticket for the voyage on this route cost 35 kopecks, while the second-class ticket cost 20 kopecks. the steamboat ‘kronprincesė’ made one voyage to nemenčinė a day, which took three hours. under the rule of poles, the navigation on the neris was very intense. according to the statistical data, the number of passengers carried by ships was almost equal to that carried by buses, taxis and phaetons and made 105 thou. people a year. in 1923, three steamboats sailed under the polish flag. two of the steamboats (‘žvaigždė’ and ‘gardinas’) were mentioned above and by that time belonged to h. janowicz, who renamed them to ‘kurier’ (‘courier’) and ‘sokół’ (‘falcon’). the other steamboat, ‘śmigly’ (‘pliant’), belonged to k. borowski. these steamboats used to make 8 voyages on workdays and 16 voyages on the days off from the city centre to verkiai. a larger steamboat, ‘pan tadeusz’, used to make 3 voyages on workdays and 6 voyages on the days off from the second landing in pospieška (at the end of antakalnis). it is believed that in the 40s the steamboat ‘vilija’ was also sailing the neris. just before world war ii, the company of the janowicz brothers bought an imposing two-deck recreational steamboat, ‘sobieski’, which used to sail to verkiai. it had passenger cabins of various classes and a buffet where passengers could order soft drinks, ice cream and even hot snacks. the steamboat used to make two voyages a day, but only on holidays. according to historian m. gajewski, after the war, in 1948, three repaired steamboats called ‘spartak’, ‘s. nėris’ and ‘falcon’ were sailing on the neris. he thought that those were the above mentioned boats (two of them renamed again and the third one retaining its old name) (gajewski 2010). the 50 year old steamboats ceased their work in the period of 1955-1956, when the building of 27 m long passenger ships with ‘moskwich-544’ diesel engines was started in the kaunas winter port. the new ships could carry up to 133 passengers and their speed reached 19 km/h. the ships of this type sailed on the neris, nemunas, kaunas reservoir and the lakes of trakai. the vilnius steamboat line had five boats of this type named ‘tashkent’, ‘ryga’, ‘kiev’, ‘s. nėris’ and ‘vilnius’. at a certain period of time, only three of them were used, while two others were being repaired. they were sailing on the route from the commonly used landing to valakupiai and to the vingis park (until 1974, when the neris became shallow due to the destructive actions of byelarussians). now, only one of these ships, ‘ryga’, makes short voyages during the summer. journal of sustainable architecture and civil engineering 2015/4/13 70 the role of the neris river in the urban composition of vilnius for many centuries, vilnius has had only one bridge. boats and rafts used for the communication between the banks of the river (and two parts of the city). according to the data of the year 1832, there were already nine of them in the vilnius region. this was also the reason why the city did not grow on both sides of the river. until the 19th century, the buildings concentrated only on the left bank. the right bank of the river had only a few buildings, and one of them was the st. rapolas church. the city had not expanded down the river either. the area on its left bank was ‘closed’ for a long time. below lukiškės and above the vilnia’s mouth there were only some poor villages along the neris river. this area was attractive only to the owners of breweries, landings, timber yards, small factories, etc., but not for those who could build luxurious palaces. as concerns its compositional structure, vilnius was expanding ‘with its face averted from the river’, as it is called in the theory of urban development. beside the above-described factors, there was another reason for this type of city development. the fact is that, until the beginning of the 20th century, the road or trail of 10 sieksniai (fathoms) on each bank of the shipped river, canal or other waterway, including the neris, belonged to the state, according to the statute of waterways, which was valid in the russian empire for several centuries. this area called ‘bichevnik’ (towpath) was required for ‘burlaki’ (barge haulers, who pulled boats or ships upstream). this zone on the bank had to be free, not planted with trees or bushes and have a gentle sloping to the water. it was only allowed for people to repair boats, store cargo, tie up rafts and spend the night there. this requirement prevented from ‘front development’ of the riverside territories in many cities, as well as the provision of embankments with the equipment required for recreation and promenades in many cities. it should be stated that despite its long history vilnius could never be truly characterized by such urban development concepts as ‘embankment-street’, ‘embankment-square’, ‘embankment-city park’ or ‘embankment-beach’ (grunskis 2004). however, these characteristics make most of the world cities and towns more beautiful and attractive. t. grunskis and l. nekrošius, who studied the conditions of sociocultural development of the embankments of the cities situated on the river banks or the seashore, gave their seven types, based on the embankment typology offered by c. moughtin (moughtin 1999). though the authors do not mention the above ‘bichevnik’ requirements, the conclusion can be drawn from the implications of their paper that the functional and compositional connection between vilnius and the river can be best achieved with the variant of a riverside city, ‘turning its back to the river’.13 1 the neris river played a very important role since the establishment of lithuania’s capital, vilnius and in the years of its further development. its ford (“brasta” in lithuanian), widely known in the ancient ages, had existed not far from the castle for a long time (until the first bridge, the predecessor of the current green bridge, was built in this place) and was an important place through which numerous ways linking southern and northern parts of lithuania passed. for many centuries the neris river has been heavily navigated and has become one of the main waterways in the country.13 2 in fact, in some regions of the european countries, shipping by the inland waterways makes about 40 % of all forms of transport. for example, transporting cargo via the inland waterways in belgium increased by more than 50 % in 1997-2004, while in france, it exceeded 35 %.now, 12.5 thou. ships with cargo-carrying capacity equal to that of 440 thou. trucks are used. on january 17, 2006, the european commission officially announced in its communique that insufficient capacity of land transport, as well as traffic jams and delays, produce a negative effect on the competitive ability, the environment and quality of life. therefore, the eu supports a transfer to more energy-efficient, cleaner and safer transport facilities. in this context, the role 13 this is a common characteristic of a riverside city. this feature, ‘a town turning its back to the river’, was described in many books and examined in the urban development studies (wierzbycka 1996; szwed 2014). conclusions 71 journal of sustainable architecture and civil engineering 2015/4/13 of inland water transport becomes more important. the commission emphasized the need for taking measures to ensure a more effective use of market possibilities for increasing the attractiveness of shipping by inland waterways. it should also be noted that the pollution produced by inland water transport makes only two-fifths of that produced by the automobile transport, while its safety is 2.5 times higher than that of the above land transport. it is believed that inland water transport and short-distance shipping, as well as rail transport, can largely contribute to maintaining a sustainable transport system (lapinskas 2009). 3 there is hardly any other capital city in the world, situated on both sides of the river like vilnius, which would not take advantages of these favourable natural conditions in the 21st century. this feature of a city or a town was considered to be important in all times, and architects and designers tried to use it for the public interest. thus, the schools of architecture in the west have a special programme of studies called ‘water front architecture’. therefore, it seems that, in spite of the complicated condition of the neris riverbed, it would be possible to renew a more intense use of the available resources, which was described above, based on the much more effective water resource management and navigation equipment. 4 to create the conditions in the lower reaches of the neris for intense shipping of freight and passenger vessels between vilnius and kaunas is hardly possible because it would require large investments.the situation is, however, different with shipping on the neris within the territory of vilnius. the neris stretch of 7.5 km between valakupiai and žvėrynas bridges has already been declared to be the inland waterway of great importance to the state. according to the long-term plans, the neris stretch from the verkiai regional park to the lazdynai bridge could also be used in the future for transporting tourists, holiday-makers and other people by ships and for recreational purposes. there are many other plans, projects and visions, which require only some determination, initiative and finances. 5 the realization of clearly defined original ideas of reviving the traditions associated with the neris and its embankments can help to make them attractive for the inhabitants and guests of vilnius, the capital of lithuania and resume some of old historical traditions. references daubarytė, k.2010. kultūros paveldo išteklių panauda ir gyvosios tradicijos gaivinimo galimybės neries upės turizmo infrastruktūroje kauno mieste ir jo prieigose.[use of cultural heritage resources and traditions of reviving turism infrastructure in the river neris at the kaunas city and its outskirts] final work of master studies, vytautas magni university, kaunas długosz, j. 1868. dievo žaislas. lenkijos istorija. nuo seniausių laikų iki 1795 metų. [toy of gods. history of poland since the oldest times to the year 1795] , vol. i , publishing house of lithuanian writers` union, vilnius gajewski, m. 20123, wierszupa: za rogatkami antokola [wiershupa beyond the boundaries of antakalnis] www.magwil.lt/archiwum/202/mmv10/ pazd13.htm grunskis,t., nekrošius, l., 2004. istorinėssociokultūrinės krantinių raidos sąlygos lietuvos miestuose iki xx a. [historical – sociocultural conditions evolution of embankments` in lithuanian cities to the xx century], town planning and architecture 28(1), p.119-134 jurkštas, j.1990. senojo vilniaus vandenys. [waters of ancient vilnius], vilnius, science, 139 p. kilkus, k., stanevičius,e., 2011. lietuvos vilnius universitety press knapkis, s. 2011. klaipėdoje primins lietuviškąjį burlaivį – vytinę [the first lithuanian sailer – vytinė will be reminded in klaipėda], http://www.want.lt/ naujienos,/klaipeda/miesto-pulsas/klaipedoje – primins-lietuviska-burlaivi-vytine-363236#, kudaba, č.1985. nerimi.[along the river neris], mind, vilnius: lapinskas, a.2009. mūsų upės – per seklios laivams. [our rivers are too shallow for boats], [geography of lituanian waters], renascence. n.19 journal of sustainable architecture and civil engineering 2015/4/13 72 the little soviet lithuanian encyclopedie, 1968. vol. 2.,vilnius mikulewicz i. 2008. “romantyzm myśli, pozytywizm dzialań“, [romantism of mind, positivism of activity], http://www.tygodnik.lt/200809/bliska1.htlm moughtin, c.1999, urban design: street and square. oxford, architectural press, 134 p. pawłowski, s. 1911. niektóre kanały spławne na ziemiach polskich. [some navigable rivers in the territories of poland], union publishing house, lwów samalavičius s., compiled by ragauskas, a.2011. vytinė ir strugas – tipiški ldk vidaus laivybos laivai. [vytinė and strugas – tipical boats of internal navigation in the lithuanian grand duchy], orbis lituaniae.economy in xvii – xvii centuries. słownik geograficzny królewstwa polskiego i innych krajów słowiańskich, 1893 [geographical vocabulary] , vol.13, warsaw szwed , j, 2014, współzesna rola bulwarów w mieście [modern role of city`s boulevards], warszawa šėmienė, a.1994. kaip arsenalas neteko bokštų [how arsenal has lost its towers], echo of lithuania, n.248, december 30,1994 tyszkiewicz, k.1871. wilija i jej brzegi, pod względem hydrograficznym, historicznym, archeologicznym i etnograficznym. [vilija and its banks in the aspect of hidrography, archaeology and ethnography], publishing house of j.i. kraszewsky, dresden vaitkevičius, v.2005. vilija – neris: vardo istorijos vingiai, [vilija--neris: historical windings of its name], people`s culture n. 6 (105) vokiška kronika, [german chronicle], library of lithuanian science academy, f.9 wierzbicka, b. 1996. miasto tyłem do rzeki. [city`s back turned to the river] association of heritage wardship, warsaw wisłocki s. 1937, regulacja rz. wilii w obrębie m. wilna, [regulation of river wilija in the boundaries of vilnius], economy of waters, n.2 žemulis, f. 2007. lietuvių žygeivius užbūrė baltarusių svetingumas [lithuanian hikers were charmed by the hospitality of byelorussians], http://lzinios.lt/ lzinios/print.php?idas=109539 кибург, к.1868. дневник главного начальника гошпиталей тевтонского ордена. [diary of the principal of the teutonic hospitals], record of st. petersburg imperial university, vol. 2, ed. 1-6 (translation from polish by m. smirnow) киркор, а. к. 1882. литовский язык и литовская мифология [lithuanian language and lithuanian mythology], picturesque russia, vol . 3, st. petersburg reference to this paper should be made as follows: vanagas j., 2015. navigation on the neris river and its importance for vilnius, journal of architecture and urbanism ... jurgis vanagas professor emeritus department of urban design, vilnius gediminas technical university main research area urban theory, urban sociology and ecology, regional planning, history of lithuanian towns and cities, architecture journalism and critique address: pylimo g.26/trakų g.1,lt-01132, vilnius, lithuania e-mail: jurgis.vanagas@gmail.com about the authors journal of sustainable architecture and civil engineering 2016/3/16 70 *corresponding author: p.christou@frederick.ac.cy the developments of the analytical fragility methods in seismic risk assessment – a review http://dx.doi.org/10.5755/j01.sace.16.3.16500 ahmed moussa, petros christou* frederick university, 7, y. frederickou str., pallouriotisa 1036, nicosia, cyprus nicholas kyriakides cyprus university of technology, 2-6 saripolou, 3603, limassol, cyprus received 2016/09/24 accepted after revision 2016/11/07 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 70-81 doi 10.5755/j01.sace.16.3.16500 © kaunas university of technology the developments of the analytical fragility methods in seismic risk assessment – a review jsace 3/16 the fragility curves are an essential tool in the seismic assessment of structures and provide a versatile tool to conduct vulnerability analysis for retrofitting and strengthening purposes. the available advancements of computer computational power led to the improvement of the efficiency of the analytical fragility curves. therefore, this paper focuses on reviewing the recent research developments in the analytical fragility analysis methods. furthermore, the developments of the intensity and damage measures are presented. in addition, the joint hazards effects on structural fragility are addressed particularly for the environmental degradation and mainshock-aftershock sequence. finally, recommendations are presented for improving the fragility analysis and highlighting the possible future research areas. keywords: capacity-spectrum method, corrosion, fragility curves, incremental dynamic analysis, mainshock-aftershock, seismic risk assessment. the earthquake devastating effects on the built environment are increasing over the past years in spite of the current efforts and continuous research on seismic design and structural retrofitting. in order to mitigate the losses due to earthquake hazards, it is mandatory to conduct earthquake risk assessments for the existing buildings stock. the earthquake risk assessment is defined as the probability of damages or losses due to earthquakes, which is represented by the fragility curves. the fragility curves represent the probability of exceeding a structural performance level in response to increasing earthquake intensity. the methods used to derive the fragility curves can be grouped into four main categories; empirical, expert elicitation, analytical and hybrid methods. the fragility curves based on the empirical methods are derived from the observed data after earthquakes. several researchers developed fragility functions based on extensive surveys for elements that were subjected to earthquake loading. the empirical fragility functions are dependent on the database where the damage data were collected from. in general, the data are obtained either from a single earthquake event or multiple events. the advantage of deriving fragility curves from real observed data is that it accounts for soil-structure interaction (ssi), site introduction 71 journal of sustainable architecture and civil engineering 2016/3/16 effects and variation of the structures response and their failure mode. however, the major drawback is that the derived curves are specifically related to a particular area which is characterized by certain soil conditions, earthquake properties, i.e. magnitude, depth, site to source radius, etc., and structural capacity. furthermore, most of the empirical fragility curves are based on low to medium magnitude events, hence, the curves may provide unreasonable information related to greater magnitudes. the expert opinion method is totally dependent on the appointed experts who assess the mean loss or the probability of damage for the given elements at risk. expert elicitations are collected and combined together by two broad approaches; mathematical and behavioral. the method is significantly useful in areas with low real damage data from past earthquakes or in the absence of reliable analytical models. furthermore, more reliable curves yield when the method is calibrated with the empirical or analytical approaches. nevertheless, the fragility curves obtained from expert elicitations are only dependent on the experience of the engineer. moreover, the outcomes of the method are hard to be applied or used in other countries that have different earthquake activity. the analytical approach is used to obtain the damage distribution through the elements at risk by using numerical methods. the structural systems are modelled and analyzed to establish a relationship between the damage levels and the ground motion at different intensities. numerical models should be created to find the response of the structures under seismic loads and a choice has to be made between the accuracy and complexity of the models and cost-efficiency of the models. furthermore, the widely used analytical methods are capacity spectrum method (csm) and incremental dynamic analysis (ida). the csm is a cost-effective method which gives a quick estimation of the structures’ response under earthquake loads, however, the actual behavior of the structures may be different. on the other hand, the ida shows the actual behavior of structures under a suite of ground motions. however, it is a time demanding method depending on the complexity of the models and material type. the hybrid method utilizes the combination of any two of the methods, which are described above. for example, the analytical models could be calibrated with a real observed data from past earthquakes or from expert judgement data. it is a very effective method since the combination of any two methods should compensate the lack of the other. there are several analytical approaches for the development of fragility curves that are presented in the literature. however, the most widely used approaches are the csm and ida. hence, the aim of this paper is to review the development and application of both methods in the field of fragility analysis. additionally, the intensity measures (im) and damage measures (dm), which are significant parameters in deriving the fragility curves, are also reviewed. furthermore, besides the hazard from earthquakes, the importance in addressing other hazards in fragility analysis such as environmental degradation and mainshock-aftershock sequence (ms-as) are addressed. the earthquake intensity measure (im) is a significant index that characterizes the ground motion and correlates with the response of each element at risk (e.g. buildings, pipelines, highways, etc.) from the structural engineering point of view. there are numerous ims that are proposed in the literature and selecting the appropriate im is a critical task in earthquake risk assessment. in general, the ims can be classified in two main categories: empirical im and instrumental im. the empirical im are generally used for the derivation of empirical fragility curves that are expressed in terms of macroseismic intensity. the macroseismic intensity scales, e.g. mercalli-cancani-sieberg, modified mercalli intensity etc., are used to quantify the observed damage effects caused by earthquakes. conversely, the derivation of the analytical and hybrid fragility curves is related to the instrumental im, e.g. sa, pga, pgv, etc. furthermore, the instrumental ims are significantly more ground motion intensity measure journal of sustainable architecture and civil engineering 2016/3/16 72 accurate than empirical ims and are more representative of the seismic intensity characteristic. it is important to select the most appropriate im that can sufficiently relate to the chosen damage measure. according to mackie and stojadinovic (2003, 2005), six features define the optimum im: practicality, effectiveness, efficiency, sufficiency, robustness and computability. practicality simply means that the im, to some extent, is directly correlated to known engineering quantities such as displacements or rotations. in addition, the practicality of im can be verified by analyzing the results of a structural response under ida or time history analysis. a sufficient im is the one that is statistically independent from the earthquake magnitude and source-to-site distance (r), padgett et al. (2008). furthermore, when the relation between an im and engineering demand parameter (edp) can be evaluated in closed form, it is called effective im, mackie and stojadinovic (2003). the most important and recognized feature is the efficiency which describes the variation in edp for a given im. in other words, the dispersion of the calculated seismic demand is less when an efficient im is used, shome (1999). determining the number of ground motion records which will be used in scaling and ida is critical in the fragility assessment process. in fact, it affects dramatically the accuracy of the results and the computational time. asce\sei 7-10 (2010) recommended that three ground motion records are the minimum and if less than seven are used, the design dm values should be taken as the highest value among the seven records. however, reyes and kalkan (2012) argued that asce\sei 7-10 procedure is conservative when less than seven records are used. furthermore, hancock et al. (2008) concluded that the sufficient number of ground motion records to obtain reasonable results depends on the dm used in the analysis. moreover, cimellaro et al. (2011) argued that the use of sa as im instead of pga could reduce the minimum required ground motion records with achieving an accurate estimation of seismic demands. the damage measures (dm) are as important as intensity measures in conducting a fragility analysis. each damage measure highly affects the shape of the derived fragility curves. in general, the proposed damage measures in the literature can be grouped into three main categories: dynamic parameters of the structure, displacement parameters and displacement and cumulative damage, kyriakides (2007). extensive fragility analysis has been carried out using displacement parameters such as lateral interstorey drift (isd), residual drift ratio and ductility ratio (dr). the commonly used displacement damage indicator is isd, which is the maximum relative displacement between two storeys normalized to the storey height. early estimation of isd threshold values were proposed by culver (1975) at different damage levels using real damage data observed from damaged buildings. the author suggested that when the isd value is equal to h/100 or h/25, it corresponds to non-structural damage or severe structural damage, respectively. several researchers attempted to propose several damage thresholds for isd, e.g. elenas (2001), rossetto (2005) and nishitani et al. (2015). however, isd does not provide information about the location of the damage and the residual capacity of the structure. therefore, it was argued that the residual drift is a significantly important dm parameter in seismic assessment of structures and cost analysis of repair and retrofitting, tesfamariam and goda (2015). hence, it was recommended by several researchers to use residual drift ratios for seismic risk assessment of structures, e.g. howary and mehanny (2011), bojórquez and ruiz-garcía (2013) and ruiz-garcía and aguilar (2014). furthermore, the use of dr, which is the ratio of maximum deformation to yield deformation, was utilized in seismic risk assessment to predict the location of damaged structural elements for the purpose of retrofitting and strengthening, sfahani et al. (2015). nevertheless, the previously mentioned dms do not consider the cyclic effects of seismic loads due to its dynamic nature. hence, park and ang (1985) developed the most popular dm in disseismic damage measure 73 journal of sustainable architecture and civil engineering 2016/3/16 placement and cumulative damage category, which is shown in equation 1 that can take into account the effect of low-cycle fatigue and energy dissipation on structural capacity. however, the proposed dm is time and cost demanding because of the need for laboratory or field data to calibrate the constant β. where: δm maximum experienced deformation; δu ultimate deformation; qy yield force; β constant determined by experimental calibration. (1) (edp) can be evaluated in closed form, it is called effective im, mackie and stojadinovic (2003). the most important and recognized feature is the efficiency which describes the variation in edp for a given im. in other words, the dispersion of the calculated seismic demand is less when an efficient im is used, shome (1999). determining the number of ground motion records which will be used in scaling and ida is critical in the fragility assessment process. in fact, it affects dramatically the accuracy of the results and the computational time. asce\sei 7-10 (2010) recommended that three ground motion records are the minimum and if less than seven are used, the design dm values should be taken as the highest value among the seven records. however, reyes and kalkan (2012) argued that asce\sei 7-10 procedure is conservative when less than seven records are used. furthermore, hancock et al. (2008) concluded that the sufficient number of ground motion records to obtain reasonable results depends on the dm used in the analysis. moreover, cimellaro et al. (2011) argued that the use of sa as im instead of pga could reduce the minimum required ground motion records with achieving an accurate estimation of seismic demands. 3. seismic damage measure the damage measures (dm) are as important as intensity measures in conducting a fragility analysis. each damage measure highly affects the shape of the derived fragility curves. in general, the proposed damage measures in the literature can be grouped into three main categories: dynamic parameters of the structure, displacement parameters and displacement and cumulative damage, kyriakides (2007). extensive fragility analysis has been carried out using displacement parameters such as lateral interstorey drift (isd), residual drift ratio and ductility ratio (dr). the commonly used displacement damage indicator is isd, which is the maximum relative displacement between two storeys normalized to the storey height. early estimation of isd threshold values were proposed by culver (1975) at different damage levels using real damage data observed from damaged buildings. the author suggested that when the isd value is equal to h/100 or h/25, it corresponds to non-structural damage or severe structural damage, respectively. several researchers attempted to propose several damage thresholds for isd, e.g. elenas (2001), rossetto (2005) and nishitani et al. (2015). however, isd does not provide information about the location of the damage and the residual capacity of the structure. therefore, it was argued that the residual drift is a significantly important dm parameter in seismic assessment of structures and cost analysis of repair and retrofitting, tesfamariam and goda (2015). hence, it was recommended by several researchers to use residual drift ratios for seismic risk assessment of structures, e.g. howary and mehanny (2011), bojórquez and ruiz-garcía (2013) and ruiz-garcía and aguilar (2014). furthermore, the use of dr, which is the ratio of maximum deformation to yield deformation, was utilized in seismic risk assessment to predict the location of damaged structural elements for the purpose of retrofitting and strengthening, sfahani et al. (2015). nevertheless, the previously mentioned dms do not consider the cyclic effects of seismic loads due to its dynamic nature. hence, park and ang (1985) developed the most popular dm in displacement and cumulative damage category, which is shown in equation 1 that can take into account the effect of lowcycle fatigue and energy dissipation on structural capacity. however, the proposed dm is time and cost demanding because of the need for laboratory or field data to calibrate the constant β. � � ���� + � ���� � �� eq.1 where: δm maximum experienced deformation δu ultimate deformation other similar dms were proposed and used in the derivation of fragility curves that are mainly suitable for assessing the seismic vulnerability of structures due to mainshock-aftershock sequence as well as investigating the total energy induced by ground motion shaking, e.g. fajfar (1992), luco et al. (2004), bojórquez et al. (2008), cosenza et al. (2009) and mander and rodgers (2013). the structures’ dynamic parameters, i.e. natural frequencies, mode shapes and damping, are used as damage measures by several researchers. in general, by knowing the parameters, they could be used in calibrating the elastic properties for numerical modelling, detecting the structural behavior after retrofitting or damage and predicting its response under earthquake loads, michel (2008). bindi et al. (2015) used the ambient vibration to assess the seismic response of an 8-storey reinforce concrete (rc) building which was one of the largest northern greek hospitals. the natural frequencies and mode shapes of the building were extracted using the peak picking and frequency domain decomposition. it was concluded that the results obtained from the ambient vibration could be used to produce more reliable models based on their existing conditions. furthermore, karapetrou et al. (2016) presented a comprehensive methodology for utilizing the obtained field data for a structure, i.e. dynamic properties, in the derivation of time dependent fragility curves. it was the continuation of the work done by bindi et al. (2015), i.e. the building and its dynamic properties were the same. the monitoring field data and the initial finite element (fe) model were used to form and update a 3d nonlinear fe model, then ida were performed to derive the time-dependent fragility curves. the 3d fe model took into account the existing structure’s conditions such as the strength degradation due to time, possible preexisting damages, changes in geometry or mass distribution, etc. the analytical approach is used to obtain the damage distribution through the elements at risk by using numerical methods. the structural systems are modelled and analyzed to establish a relationship between the damage levels and the ground motion at different intensities. two main approaches are used for the analysis which are the capacity spectrum method (csm) and the incremental dynamic analysis (ida). capacityspectrum method the general methodology for the csm is to perform a static nonlinear pushover analysis, obtaining the pushover curve, which shows the base shear vs the lateral displacement. then, the pushover curve, also named as the capacity curve, is converted to the capacity-spectrum curve, which is bilinear or multilinear acceleration-displacement curve that describes the structural behaviour when subjected to gravity and lateral loads. the performance point is defined by superimposing the capacity spectrum curve with the earthquake demand curve, i.e. the response spectra. the performance point is the interaction point between the two curves, freeman (2004). eventually, after finding the performance point for each seismic intensity, the fragility curves can be constructed. the main advantage of csm is that it is a reliable simplified static method to used simulate the dynamic behaviour of the seismic events. the csm was first proposed by freeman et al. analytical fragility analysis methods journal of sustainable architecture and civil engineering 2016/3/16 74 (1975), where it was used as a rapid evaluation method to assess the seismic vulnerability of the buildings in puget sound naval shipyard, washington. since introducing the method, it was used in several guidelines and codes. for example, three alternatives for the application of csm were proposed in atc-40, namely procedures a, b and c. procedures b and c were difficult to be used and programed due to the over simplifications considered in procedure b and the extensive graphical components in procedure c. however, procedure a is a simple analytical method and easily applicable in software codes. this method requires an iterative process to reach convergence on the performance point until the demand spectrum intersects with the capacity spectrum within acceptable tolerance. nevertheless, fajfar et al. (1999) and chopra and goel (2000) criticized the proposed procedure a, since it was concluded that it underestimates the structural deformation. therefore, in fema440 modifications had been made to procedure a especially for the part related to the calculation of equivalent viscous damping which is a representation of hysteretic damping. in addition, the modified acceleration-displacement response spectrum (madrs) was introduced to improve the representation of seismic demand by reducing the elastic response spectrum that depends on the increase in ductility and damping. furthermore, the csm was adopted in euro code 8. until today, researchers extensively use the csm to derive fragility curves for different buildings’ typologies. gencturk and elnashai (2008) improved the csm presented in atc-40 by proposing an advanced csm that directly incorporates inelastic response history analysis of bilinear systems. furthermore, the advanced method was validated by conducting a shake-table full-scale test of two timber frame structures. by comparing the obtained results from the tests and the advanced method, it was observed that the proposed method gives more reliable displacement predictions than the existing methods. nevertheless, it failed to provide reliable predictions for irregular structures. kyriakides et al. (2014) proposed a framework to conduct a probabilistic seismic vulnerability assessment of low and midrise substandard rc structures, which were designed without seismic codes, based on the modified csm presented in fema440 to consider the degradation in the structural capacity of the substandard structures. the obtained pushover curves of the mdof structures were converted to equivalent capacity curves of sdof systems as required by csm. the buildings’ frames were modelled in the software drain 3dx, developed by prakash et al. (1994), using fiber elements. the models were capable of capturing the gap and pullout effects in hinges and the shear failure in the bonds. similarly, ali et al. (2015) adopted kyriakides et al. (2014) and other researchers to develop vulnerability curves for a typical low engineered structures in pakistan. drain 3dx was used in the modelling of the two generic 2d frames that are deigned under gravity loads and with insufficient reinforcements. the csm was used to assess the structural response under the seismic loads. the derived vulnerability curves were compared with empirical vulnerability curves developed by geohazards international (ghi). it was concluded that the empirical curves related to pakistan underestimate the predicted damage for the existing buildings in pakistan. haldera and paul (2016) investigated the vulnerability of low rise buildings designed for the gravity loads according to the indian code is 456 (2000). 2d nonlinear frame elements were modelled in sap2000 and the csm was performed according to atc-40, while the lateral load distribution was given by fema 356. finally, the fragility curves were derived following the hazus methodology. rossetto et al. (2016) presented an innovative approach based on csm and the use of inelastic response spectra derived from earthquake ground motion accelerograms for the derivation of fragility curves. the proposed method was named fragility through capacity spectrum assessment (fracas). two four rc frames were used to examine the new method, one was designed without seismic code and the other with seismic code. the main steps of fracas are summarized as follows: 75 journal of sustainable architecture and civil engineering 2016/3/16 1 the obtained capacity curve is converted to an idealized trilinear curve. 2 the idealized trilinear curve is discretized into analysis points, which represents the elastic stiffness, ductility and post-elastic properties of the capacity curve. 3 the performance points (pp) are estimated by intersecting the capacity curve with the spectrum curve using the elastic and inelastic part of the response-spectrum curve, without the need to perform iterations. 4 the selected engineering demand parameter (edp) for each pp is determined by finding the corresponding load step of the pushover analysis. 5 the fragility curves are derived through a statistical curve fitting approach from the set of im and edp. the authors compared fracas with the nonlinear time history analysis and concluded that the former is reasonably capable of capturing the response of both case studies. furthermore, the fracas was able to account for the record-to-record variability; hence, it was reflected in the derived fragility curves. incremental dynamic analysis the ida is a nonlinear dynamic analysis method that provides a continuous picture of the structural response under seismic excitations starting from the elastic state, to yielding and finally to collapse. the concept of ida was proposed by bertero (1977), nevertheless, it recently became popular and extensively used in fragility and vulnerability analysis. generally, the ida procedure involves performing multiple nonlinear time history analysis under a suite of scaled ground motion records that their intensities should be chosen wisely in order to cover the effect of earthquake shakings to structures starting from elasticity to global dynamic instability, vamvatsikos and cornell (2002). the curves obtained from ida, termed ida curves, show the relationship between the edp versus im of the applied scaled ground motion records as shown in fig. 1. three components determine the reliability of ida results, which include the well-established nonlinear structural model, the proper selection of ground motion records and the selection of efficient edps and ims. it is important to select good scaling levels for the ground motion record to ensure reasonable estimates of the distribution of edp for a given im provided, that their statistical relationship is effectively independent from the earthquake magnitude and source-to-site distance (r), vamvatsikos and cornell (2004). vamvatsikos and cornell (2002) argued that the ida curve produced by a single ground motion record is not enough to define the behavior of a structure. the authors performed ida on a 5-storey steel braced frame subjected to four different ground motions as shown in fig. 2. each curve represents the structural response to the imposed seismic demands. hence, sufficient number of ground motion records should be included in the analysis. the computational time required to derive fragility curves by ida is relatively more than csm. however, the curves derived by ida are able to capture accurately the seismic response of most of the engineering structures. owning to the accuracy of the ida in capturing the structural behavior and response due to seismic excitations and to the increasing advancement in computers capabilities, the ida is used extensively in deriving fragility and vulnerability curves for almost all of the engineering structures. for example, saruddin and nazri (2015) developed fragility curves for the representing building stock in malaysia, i.e. rc and steel moment resisting frames. a three story frame representing low-rise and a six story frame representing mid-rise buildings were designed according to eurocodes 2, 3, 4 and 8. ida was performed using the sap2000 software and a set of seven ground motion records were selected. the ground motion records were scaled by increasing the peak ground journal of sustainable architecture and civil engineering 2016/3/16 76 fig. 1 ida curve vs pushover curve, vamvatsikos and cornell (2002) fig. 2 typical ida curves for a five storey building under four different earthquakes, elnashai and di sarno (2008) acceleration (pga) by 0.05g until 0.6 g. finally, several fragility curves were derived to account for the variation in materials and height. furthermore, melani et al. (2016) performed seismic risk assessment and financial risk analysis of a low-rise rc frame structure. three frames were considered in the analysis with the same height, however they were designed differently. the results obtained from the ida were used in the financial risk analysis, which was expressed in terms of 77 journal of sustainable architecture and civil engineering 2016/3/16 the loss ratio. the loss ratio was defined as the cost required to restore the structure to its full working condition to the replacement cost of the structure. joy and thampan (2016) investigated the effect of friction pendulum isolation system (fps) on the seismic vulnerability of a twelve-story rc hospital building located in india. the ida was carried out to find the structure response under 25 ground motion records. finally, the fragility curves were developed for the same structure with and without fps. it was concluded that the fbs reduced significantly the seismic vulnerability of the building because the fbs lengthens the first mode period, which in return reduces the earthquake induced forces. additionally, sadraddin et al. (2016) investigated the effect of shear walls’ distributions in high-rise buildings on their seismic performance. four typical twelve story high-rise buildings with the same layout configurations and different shear walls’ distributions were designed and analyzed. the ida was carried out to find the response of the considered case studies under 16 real ground motion pairs. the fragility curves were developed for all the cases. it was observed that installation of shear walls in general improved the seismic performance at all limit states. nevertheless, the most effective shear walls’ configurations appear when the shear walls are placed internally. it is necessary to include other risk hazards besides the seismic to ensure the safety of the engineering structures during their life cycle. other hazards could significantly affect the performance of the structures during earthquakes such as the deterioration due to corrosion, soil-structure interaction or the sequence of mainshock and aftershocks. with the current advancement in computers’ computational power, it is possible to incorporate theses effects in the fragility analysis of structures in order to know as precisely as possible the real response of structures in future seismic events. therefore, the effects of corrosion and mainshock-aftershock sequence are presented herein to highlight their significant effects on the performance of engineering structures. environmental deterioration in conventional fragility assessment, the impact of environmental deterioration mechanisms (e.g. corrosion, fatigue or cumulative damages from past earthquakes) is not considered. the most pronounced deterioration mechanism for reinforced concrete and masonry structures in the coastal areas is corrosion. corrosion is a long time-dependent process that causes a significant reduction in the serviceability and vulnerability of rc structures over time choea et al. (2008). moreover, the corrosion causes cracking and spalling of concrete, reduction in rebar property and loss in interfacial bond strength. these effects are discussed briefly in the following paragraphs. zhou et al. (2014) have concluded that cracking of concrete decreases the load bearing capacity of structures as well as shortens their service life. similarly, the presence of concrete spalling can cause an overestimation of the flexural capacity of rc structures. furthermore, the quantification of reduction in rebar property is considered by the loss of cross sectional area of the rebar, which could cause a premature fracture before the reach of the rebar’s yield limit. additionally, kashani et al. (2013) observed that the buckling capacity of the corroded bar was degraded by 20% due to only 10% mass loss of the rebar mass. karapetrou et al. (2013) investigated the impact of corrosion on low and mid-rise rc structures within the framework of reakt project. it was found that the loss of steel reinforcement cross sectional area due to corrosion (t = 50 years) ranged from 24% to 53% of the initial cross sectional area. furthermore, the fragility functions of the corroded low and mid-rise models experienced a considerable increase for the same ground motion compared to the uncorroded models, which proves the effect of environmental deterioration. bajaj (2012) showed that the interface bond behavior between the steel and concrete is significantly affected by the corrosion level. it was confirmed, that the bond strength increases due to the increase in corrosion level up to a critical percentage, which depends on the used concrete material, and then decreases. in addition, kivell (2012) argued that the stiffness reduction of interface effect of joint hazards on the fragility of structures journal of sustainable architecture and civil engineering 2016/3/16 78 bond and its increase in strain penetration due to corrosion raise two critical problems for seismic design and assessment. first, the increased strain penetration induces the concrete members to yield at larger curvatures, reduces steel bar strains at a given curvature and effects energy dissipation. second, the stability of the whole structure will be reduced with increased p-δ effect. mainshock-aftershock (ms-as) effect the structures in active seismic areas may experience a sequence of earthquakes because of the mainshockaftershock phenomena or other cascade events. as a result, there is no adequate time to repair and retrofit the damages of structures. it has been proven that aftershocks could cause significant damages to structures and increase fatalities and cost, even if the damages from the mainshock are minor. in general, the estimated delay time between a mainshock and the largest aftershock is within the range of several minutes to months. raghunandan et al. (2015), han et al. (2014), li et al. (2014), nazari et al. (2015). for example, an earthquake with a magnitude of m8.6 struck indonesia in 2012 followed by several aftershocks, the largest one recorded was with magnitude of m8.2 just after two hours from the main shock usgs (2012). also, after the mainshock of 2011 great tohoku earthquake in japan, 651 aftershocks were recorded with magnitudes varying from 5m to 7m usgs (2011). china has suffered significantly from wenchuan earthquake with a m7.9 which occurred on may 12, 2008 and followed by 42,719 total aftershocks just within four months after the mainshock. these tremendous aftershocks have considerably increased the number of collapsed buildings, which withstood the mainshock that in return increased the fatalities. in total, the casualties due to the wenchuan earthquake and its aftershocks were more than 70000 people and the economic loss was estimated as 150 billion u.s. dollars rms (2008). similarly, a m7.1 earthquake struck christchurch, new zealand on september 4, 2010 and five months later, a m6.3 aftershock struck the city again. this mainshock-aftershock sequence resulted in a toll of 185 deaths and $15 billion estimated economic cost, parker and steenkamp (2012). despite the devastating effects of ms-as sequence, almost all the current seismic assessment or design practice consider the effect of ms only. this lack is attributed to three main reasons; the capacity of damaged buildings after mainshocks, the complexity of the characteristics of aftershocks and their occurrence probability, and a general lack of accurate system fragility models to evaluate building performance, nazari et al. (2015). the severity of damages caused by recent earthquakes to the built environment forced the attention of engineers to assess the existing buildings stock and evaluate their vulnerabilities. therefore, abundance of fragility curves are derived for several civil structures, to predict their response in future earthquake events. the recent significant advancement in the computational power of computers facilitates the use of analytical models and reduces the time required to get the analytical results even for complex nonlinear models. the use of the csm method provides reasonable results; however, the assumption that the seismic loads are statically distributed over the building does not reflect the actual behavior of structures under seismic excitations. on the other hand, increasing the nonlinear complexity of the materials and models and performing ida will definitely render the most accurate behavior of structures. it is very important to note that besides the increasing time needed in ida, the user should have an in depth knowledge about creating detailed models and the appropriate selection of ground motions. any error related to either one of them could lead to very unrepresentative response of the actual structures. despite the abundance of the current available fragility curves, relatively few curves are available concerning the combination of fragility analysis with additional hazards probabilities. furthermore, it was noted that important structural elements such as staircases and lift shafts are not considered in the constructed models. in addition, more research is needed to assess the fragility of the buildings constructed by smart and green materials. conclusions 79 journal of sustainable architecture and civil engineering 2016/3/16 ali, m. u., khan, s. a., anwar, m. y., & gabriel, h. f. 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(2003). estimation of earthquake damage probabilities for reinforced concrete buildings. in seismic assessment and rehabilitation of existing buildings (pp. 149-164). springer. zhou, y., gencturk, b., willam, k., & attar, a. (2014). carbonation-induced and chloride-induced corrosion in reinforced concrete structures. journal of materials in civil engineering, 27(9), 04014245. ahmed moussa phd student frederick university, civil engineering department, faculty of engineering main research area earthquake engineering; soilstructure interaction; nonlinear dynamic analysis address 7, y. frederickou str., pallouriotisa 1036, nicosia, cyprus e-mail: a.mmmousa@live.com petros christou associate professor frederick university, civil engineering department, faculty of engineering main research area structural engineering; finite element analysis; earthquake engineering; nonlinear analysis address 7, y. frederickou str., pallouriotisa 1036, nicosia, cyprus e-mail: p.christou@frederick.ac.cy nicholas kyriakides post-doctoral fellow cyprus university of technology, department of civil engineering and geomatics, faculty of engineering and technology main research area seismic assessment of the vulnerability and risk of existing structures; life cycle assessment using probabilistic methods; strengthening of existing non seismically designed rc structures; performance-based design address cyprus university of technology, 2-6 saripolou, 3603, limassol, cyprus e-mail: nicholas.kyriakides@cut.ac.cy about the authors 81 journal of sustainable architecture and civil engineering 2017/1/18 corresponding author: donatas.rekus@ktu.lt peculiarities of digital levelling using automatic digital levels in civil engineering technologies received 2016/12/05 accepted after revision 2017/03/09 journal of sustainable architecture and civil engineering vol. 1 / no. 18 / 2017 pp. 81-86 doi 10.5755/j01.sace.18.1.17099 © kaunas university of technology peculiarities of digital levelling using automatic digital levels in civil engineering technologies jsace 1/18 http://dx.doi.org/10.5755/j01.sace.18.1.17099 donatas rekus*, vilma kriaučiūnaitė-neklejonovienė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania introduction construction work starts and finishes with geodetic measurements, therefore geodetic measurements and labeling are the most important components of mounting and installation work in constructions and deformation observations. modern constructions are distinguished by the size of construction objects, complexity of engineering structures and high precision of connectors and nodes of structural elements. these peculiarities and highly increased mechanization level caused changes in construction technology and character of engineering equipment of construction objects. demand for precision has greatly increased. to reach a high precision of measurements, digital geodetic instruments are used. large part of geodetic work in constructions is composed of leveling. this work contains investigations of leveling errors of digital levels. changes in leveling methodology and sources of specific errors occur using digital levels for precise leveling. these changes can affect construction-engineering measurements. precision investigations of a particular model of levels and coded staffs and digital leveling are necessary. digital investigations of technical, geometrical and methodological parameters of instruments are also needed. the scope of this presentation includes resorting to digital automatic levels and impact of their accuracy on deformation and construction measurements. keywords: coded staff, digital leveling, leveling error. construction work starts and finishes with geodetic measurements, therefore geodetic measurements and labeling are the most important components of mounting and installation work in constructions and deformation observations. modern constructions are distinguished by the size of construction objects, complexity of engineering structures and high precision of connectors and nodes of structural elements. these peculiarities and highly increased mechanization level caused changes in construction technology and character of engineering equipment of construction objects. demand for precision has greatly increased. to reach a high precision of measurements, digital geodetic instruments are used. large part of geodetic work in constructions is composed of leveling (becker et.al. 1999). the digital levels represented a breakthrough in levelling techniques using the innovative concept of reading a bar coded staff. optical readings are not longer needed. experience shows that with digital levels there is up to a 50% time saving when compared with conventional levels. the main reasons are the faster data capture as well as the shorter time and safer means of data processing, journal of sustainable architecture and civil engineering 2017/1/18 82 thanks to saving measured data on storage devices. digital levels measure and save the height and the distance to the staff at the press of a button, and calculate the height of the point. the advantages include no readings required, no copying or writing down and no calculation by hand. operation of digital levels is based on the digital processing of video information from the coded staff. at the beginning of measurement a visual pointing of the instrument to the surface of leveling meter is performed. after that the instrument automatically points the focus of its optical system on the surface of the meter and then a rough correlation calculation is performed followed by the precise correlation. according to the data received in the processor of the instrument an exact distance from the axes of the instrument to the surface of the level meter is calculated. according to the information received by decoding the data from the photoelectric matrix the height of the level placing is calculated in the processor. during this operation the coded view of the meter is compared with that saved in the memory of the instrument. a true meter’s height position is determined according to the shift of the image in the photoelectric sensor (pixels) matrix. (aksamitauskas et.al. 2007) fig. 1 digital level leica dna 03 this work contains investigations of leveling errors of digital level leica dna03 (fig.1) changes in leveling methodology and sources of specific errors occur using digital levels for precise leveling. these changes can affect construction-engineering measurements. precision investigations of a particular model of levels and coded staffs and digital leveling are necessary. digital investigations of technical, geometrical and methodological parameters of instruments are also needed. the scope of this work includes resorting to digital automatic levels and impact of their accuracy on deformation and construction measurements. determination of the collimation error of the digital levels a digital level automatically compensates for the collimation error digitally performing readings in coded staffs, if such error is defined and saved in the memory of the instrument. they have the absolute collimation error abscoll and the variable error colldif, which depends on meteorological conditions. initial value of the abscoll set by a manufacturer is equal to zero seconds. the collimation error of these levels can be adjusted using maintenance program. by setting up this program, readings are automatically compensated for the earth curvature errors. checking is made by repeating the leveling of a 60 m length site line ab, which is fixed by metal poles. the line is divided into three equal sections, with two stations (fig.2). the line contains points 1 and 2, which are locations of the leveling stations (krikstaponis 2000, 2002). in the station 1, reading a1 and distance d1 are set to the closer-standing staff. then, reading a2 and distance d2 are set to the further-standing staff. measurement sequence in the station is as follows: b2, d3 and a2, d4. if abscoll = 0 and during the checking colldif = const ≠ 0, then two height differences can be calculated: methods    2111 , ddtgcolldifbah ab  (1)    4322 , ddtgcolldifabh ab  (2) 2 310 i i p     , 2 310 i ia a m m p   , 2 310 i ia a m m p   . (3) according to the weight average formula:       i i p p i~ ,    ia iia m am a p mp m ,    ia iia m am a p mp m (4) (1)    2111 , ddtgcolldifbah ab  (1)    4322 , ddtgcolldifabh ab  (2) 2 310 i i p     , 2 310 i ia a m m p   , 2 310 i ia a m m p   . (3) according to the weight average formula:       i i p p i~ ,    ia iia m am a p mp m ,    ia iia m am a p mp m (4) (2) 83 journal of sustainable architecture and civil engineering 2017/1/18 fig. 2 the scheme of the measurements of the collimation error of the digital level dna 03 starting the checking abscoll value from the memory of the level can be seen in the instrument display. after performing measurements in both stations, the variable collimation error colldif and the new absolute collimation error abscoll are calculated. both values, in seconds, are shown in the display. the new absolute collimation error is equal to the sum of the old and the newly determined variable collimation error. the absolute collimation error abscoll, taking into account colldif value, can be set to a new value or left as the old value. if the abscoll value is too large (>20”), it can be reduced or removed by adjusting the position of the middle horizontal reticle. after confirming the adjustment of the reticle position, the level calculates the correct reading a2’. visual reading to the staff with centimetric steps placed in point a is made without moving the level standing in the point 2. if the instrument is well adjusted, the calculated and the visually set readings are identical. if the difference between the readings is larger than 3 mm for the 30 m distance (colldif ≈20”), horizontal reticle should be adjusted. after the adjustment of the horizontal reticle, the collimation error is check again. during the normal measurement conditions, standard deviation of the error is about ± 2” (aksamitauskas et al. 2007). the colldif values are changing; therefore, if the surrounding air temperature changes, a new absolute collimation error abscoll should be set and saved in the memory of the instrument. in order to reduce the impact of the collimation error for the measurement results, the error values should be set at temperature closest to an average air temperature at which the further measurements will be made. during the measurements in a station when all distances to the stuffs are absolutely equal and colldif value is stable, colldif does not have any impact on the measured height difference. reading system precision of the digital levels digital levels dna03 can be used for a preferred number (1 to 99) of coded staff readings (aksamitauskas at al. 2007). the final staff reading is based on these readings. it is unknown what number of readings is optimal and how a reading precision is changing depending on the number of readings (krikstaponis 2001, aksamitauskas at al. 2007). reading system precision of the digital level dna 03 was investigated using a 47 m long base fixed by temporal metal stakes. readings were performed into two staffs set at distances. using a measurement program measure only, ten measurements into the closer and further standing staffs were made. each cycle contained different number of readings. summarized precision indexes of the experimental measurements (3)    2111 , ddtgcolldifbah ab  (1)    4322 , ddtgcolldifabh ab  (2) 2 310 i i p     , 2 310 i ia a m m p   , 2 310 i ia a m m p   . (3)       i i p p i~ ,    ia iia m am a p mp m ,    ia iia m am a p mp m (4) are provided in table 1. the reading precision depends on the distance to a staff. average precision results were calculated using the following weights (krikstaponis 2001): journal of sustainable architecture and civil engineering 2017/1/18 84 the performed investigation of the reading system precision of the levels dna03 shows that the reading precision depends on the distance between the instrument and the staff. digital levels dna03 can be used for a preferred number (1 to 99) of coded staff readings, n. this investigation shows that the most precise indicators are obtained when n ≥ 7. when n > 7, an improvement of the precision results is insignificant. therefore, the number of readings n should not be less then 7, although this would decrease the leveling efficiency. investigation of the incomplete tilt compensation of the digital level incomplete compensation of a level was examined leveling the same station with lying and angled levels. for this purpose the level was placed strictly in the middle between the staffs that were fixed on built poles, and the height difference was measured at the following bubble position of the spherical level. (fig.3) the δh of the averages of height differences for the level used in the first class leveling should not exceed 0.5 mm or 0.05 mm per level tilt minute (krikštaponis 2001). incomplete compensation of the level tilt was investigated when the distance between the staffs was 15 m. a reading obtained by digital levels is an average of several (in this case 5) readings. in this investigation, four meatable 1 summarized precision indexes of the experimental measurements n d = 14.00 m d = 33.00 m σ am am σ am am 2 0.03 0.022 0.031 0.03 0.044 0.03 3 0.023 0.018 0.018 0.05 0.043 0.06 4 0.038 0.022 0.045 0.06 0.034 0.068 5 0.02 0.014 0.03 0.03 0.036 0.068 6 0.02 0.016 0.04 0.03 0.028 0.062 7 0.03 0.012 0.033 0.025 0.016 0.041 8 0.02 0.012 0.035 0.026 0.016 0.041 9 0.01 0.013 0.04 0.01 0.016 0.042 =σ~ 0.001 =am 0.020 =am 0.032 =σ ~ 0.003 =am 0.094 =am 0.107 (4)    2111 , ddtgcolldifbah ab  (1)    4322 , ddtgcolldifabh ab  (2) 2 310 i i p     , 2 310 i ia a m m p   , 2 310 i ia a m m p   . (3)       i i p p i~ ,    ia iia m am a p mp m ,    ia iia m am a p mp m (4) according to the weight average formula: fig 3 positions of the spherical level bubble while testing a level compensator: a – bubble in the middle of the ampoule, b and c at the longitudinal inclination, d and e at the transverse inclination surement sections were made in total while changing the level height with each section. the results of the measurements are given in table 2 and table 3. the averages of the height differences and the differences of these averages δh from the average of the height difference obtained at the bubble position in the middle of the level ampoules were calculated (krikstaponis 2002). also incomplete compensation of the level tilt was investigated when the distance between the staffs was 30 m. a reading obtained by digital levels is an average of several (in this case 5) readings. in this investigation, four measurement sections were made in total while changing the level height with each section. the results of the mea a b c d e a b c d e a b c d 85 journal of sustainable architecture and civil engineering 2017/1/18 table 2 investigation of the incomplete tilt compensation of the digital level when distance is 15 m section no. height differences bubble in the middle of the ampoule at the longitudinal inclination at the transverse inclination –5 +5 –5 +5 leica dna03 nr. 01632145 s = 15 m 1 0,25984 0,25984 0,25991 0,25989 0,25982 2 0,25986 0,25982 0,25994 0,25986 0,25982 3 0,25984 0,25981 0,25987 0,25987 0,25982 4 0,25988 0,25980 0,25986 0,25990 0,25982 5 0,25989 0,25983 0,25984 0,25990 0,25987 average 0,25986 0,25982 0,25988 0,25988 0,25983 h (mm) 0,00004 -0,00002 -0,00002 0,00003 table 3 investigation of the incomplete tilt compensation of the digital level when distance is 30 m leica dna03 nr. 01632145 s = 30 m 1 0,21132 0,21132 0,21135 0,21135 0,21138 2 0,21132 0,21134 0,2114 0,21132 0,21141 3 0,21132 0,21132 0,21137 0,21139 0,21143 4 0,21132 0,21132 0,21142 0,21139 0,21144 5 0,21133 0,21132 0,21143 0,21135 0,21142 average 0,21132 0,21132 0,21139 0,21136 0,21142 h (mm) 0,00000 -0,00007 -0,00004 -0,00010 surements are given in table 3. the same, like in previous example the averages of the height differences and the differences of these averages δh from the average of the height difference obtained at the bubble position in the middle of the level ampoules were calculated. during investigation of the incomplete tilt compensation it was found that these digital levels meet the requirements for the first-class instruments. the obtained δh of the averages of height differences did not exceed 0.5 mm or 0.05 mm per level tilt minute. the colldif values are changing; therefore, if the surrounding air temperature changes, a new absolute collimation error abscoll should be set and saved in the memory of the instrument. in order to reduce the impact of the collimation error for the measurement results, the error values should be set at temperature closest to an average air temperature at which the further measurements will be made. during the measurements in a station when all distances to the stuffs are absolutely equal and colldif value is stable, colldif does not have any impact on the measured height difference. the performed investigation of the reading system precision of the levels dna03 shows that the reading precision depends on the distance between the instrument and the staff. digital levels dna03 can be used for a preferred number (1 to 99) of coded staff readings, n. this investigation shows that the most precise indicators are obtained when n ≥ 7. when n > 7, an improvement of the precision results is insignificant. therefore, the number of readings n should not be less then 7, although this would decrease the leveling efficiency. during investigation of the incomplete tilt compensation it was found that these digital levels meet the requirements for the first-class instruments. the obtained δh of the averages of height differences did not exceed 0.5 mm or 0.05 mm per level tilt minute. conclusions journal of sustainable architecture and civil engineering 2017/1/18 86 aksamitauskas, a.; rekus, d.; wasilevsky, a. 2007. impact of digital level wild na3003 error investigations on construction engineering measurements. 9th international modern building materials, structures and techniques. may 16-18, 2007, vilnius, lithuania. vilnius: technika, 1110-1114. becker, j. m. 1999. history and evolution of height determination techniques especially in sweden. geodesy surveying in the future, the importance of heights, gävle, sweden, 43–57. krikštaponis, b. 2000. matavimų analoginiais ir skaitmeniniais nivelyrais tikslumo tyrimai [meareferences surements of analogue and digital precision levels studies]. geodezija ir kartografija [geodesy and cartography]. xxvi (2): 69-72. krikštaponis, b. 2002. skaitmeninio nivelyro wild na3003 atskaitos sistemos ypatumų tyrimai [digital levels wild na3003 characteristics of the reference system]. geodezija ir kartografija [geodesy and cartography]. xxviii (2): 39–44. krikštaponis, b. 2001. geodezinių vertikalių tinklų sudarymo skaitmeniniais nivelyrais analizė [geodetic vertical network making with digital levels analysis]. doctor disertation. vilnius: technika, 2001. 36 p. donatas rekus dr., assoc. prof kaunas university of technology, faculty of civil engineering and architecture, departament of civil engineering technologies main research area calibration of geodetic instruments, height measurements, geodetic scaning technologies address studentu str. 48, kaunas lt-51367, lithuania tel. +370 37 300479, e-mail: donatas.rekus@ktu.lt vilma kriaučiūnaitė-neklejonovienė dr., lecturer kaunas university of technology, faculty of civil engineering and architecture, departament of civil engineering technologies main research area geodesy, rural development, land-use management, real estate management address studentu str. 48, kaunas lt-51367, lithuania tel. +370 37 300479, e-mail: vilma.kriauciunaite@ktu.lt about the authors 65 journal of sustainable architecture and civil engineering 2017/1/18 corresponding author: aleksandrs.korjakins@rtu.lv tyre recycling with thermal solvolysis method using microwave radiation received 2016/10/28 accepted after revision 2017/02/09 journal of sustainable architecture and civil engineering vol. 1 / no. 18 / 2017 pp. 65-72 doi 10.5755/j01.sace.18.1.16622 © kaunas university of technology tyre recycling with thermal solvolysis method using microwave radiation jsace 1/18 http://dx.doi.org/10.5755/j01.sace.18.1.16622 aleksandrs korjakins*, aleksandrs holimenkovs riga technical university, institute of materials and structures, department of building materials and products, 1 kalku street, lv-1658, riga, latvia introduction used tyres are one of the most widespread types of waste and one of the polymer materials which are most difficult to recycle. there are many different applications for used tyres today. part of the tyres can be retreated and re-used, but most of the used tyres are recycled. by dissolving the tyres, it is possible to filter out various chemical substances. these substances coming from the used tyres can be used for creating a new material or improving an existing one. one of the technologies involves adding chemically recycled tyres to the bitumen used in road pavement construction. the substances obtained from the recycled tyres can be used in the water proofing of bitumen. methods of pyrolysis and solvolysis are used for recycling tyres into raw materials. in this research tyre recycling with thermal solvolysis is studied by using a conventional oven and microwave oven in order to obtain waterproofing materials with improved exploitation properties. promising results are obtained in the pre-studies on the tyre recycling in the microwave allowing to reduce energy consumption before thermal processing of tyres as well as during the thermal processing process compared with methods involving heating in traditional furnace. dissolving time of the recycled tyre pieces depending on the size of the pieces as well as energy consumption depending on furnace type, operating temperature and time have been assessed during the experimental part. adhesive properties of the rubber-bitumen composite obtained during the experiments were tested. after testing the adhesive properties on the concrete surfaces it can be concluded that rubber-asphalt composite obtained in a microwave oven has the best adhesion because no waterproofing peeling has been found. keywords: thermal solvolysis, rubber-bitumen composite. during the last decades all countries are paying increased attention to such problems as growing production and household waste stream including the used tyres and waste utilisation or recycling. used tyres are one of the most widespread types of waste and one of the polymer materials which are most difficult to recycle. used tyre recycling problem is essential with regard to the ecology as the used tyres tend to accumulate in the locations, where they have been used (car services, aerodromes, production and public utility companies). when transported to the landfill sites (fig. 1) or thrown out in the surrounding area, the used tyres create long-term pollution of the environment due to their resistance to such environmental factors as impact of sun, oxygen, ozone as well as microbiological impact. journal of sustainable architecture and civil engineering 2017/1/18 66 today there are several options how the used tyres could be treated. small part of the used tyres is used for decoration purposes but the biggest part is recycled (urtane s., 2012). every year, around 2.5 million tons of tyres wear out only in europe, and their recycling rate reaches 90%. most of the tyres (about 40%) are burned for energy. slightly lower proportion of the used tyres (about 30%) are shredded in crumbs for further use fig. 1 used tyres at landfill site (http://www.businessequipment.ru/images/ utilizaciya-avtomobilnyhshin.jpg, 23.11.2015) either in shredded form and 20% of the used tyres are restored and exported to be reused. currently a developing trend is used tyre recycling by applying the methods of chemical recycling. the chemical recycling involves irreversible changes of the tyres and collapsed structure of the polymers. by melting the tyres it is possible to filter out various chemical substances added by the tyre producers. there are some additives that increase tyre freeze resistance or thermal resistance. other additives increase their resistance to chemical substances (zhitov r., 2013). by knowing how to preserve all these substances it is possible to change the composition of some material thus improving its properties (baldino noemi et al, 2013), (ortega f.j. et al, 2015). for example, using bitumen together with recycled tyres it is possible to obtain lower costs and higher quality thus providing possibilities for the improvement the road surface quality. there are several methods for used tyre recycling. tyres burn easily, therefore the initial method for handling the used tyres was to burn them. tyre burning is related to high emissions of fly ash that remain on the walls of chimney or in filters as well as on the leaves of plants and trees creating environmental pollution. applying the method of mechanical shredding the tyres are cut into small pieces. during the recycling process the rubber powder is obtained, which has an even increasing number of possible applications. the most important quality indicator of the powder is the size of particles ranging from 180 mkm to 12 mm (http://www.videsvestis.lv/content.asp?id=41&what=12, 13.10.2015). applying the granulation of tyres it is possible to use the rubber granules in the process of paving and asphalt production. this type of asphalt contributes to a longer service life of the new tyres. applying pyrolysis for the tyre recycling in a high temperature without air supply results into their decomposition, namely, gas condensate mixture, fly ash and metallic cord are obtained as the final products. heating ability of the obtained condensate is equal to those of the fuel oil, therefore it can be used as the heating fuel (papin a., 2015). fly ash can be used as a filler in the rubber and plastic recycling but metallic cord in the metal scrap recycling. utilisation and further recycling of the used tyres proceeds in several stages: tyre tread and beads are removed with the side cutting equipment (for the dense stocking of the tyre parts), tyre parts are placed on the retort, the lid of the retort is closed and it is placed in the pyrolysis furnace set at 450oc (http://ztbo.ru/o-tbo/stati/piroliz/pirolizshin-i-pokrishek, 15.10.2015). pyrolysis gas is formed during the decomposition; it moves through the cooler forming a pyrolysis oil. part of this oil is redirected to the burner in order to sustain the pyrolysis process (papin a., 2015). one of the most promising used tyre recycling technologies is thermal solvolysis, which has been a research object of this scientific research. thermal solvolysis of rubber crumbs proceeds in lower temperatures compared to the pyrolysis process. it allows to increase the amount of liquid product as less gas is formed as well as it is possible to modify quality of liquid products due to different solvent composition. rubber decomposition with solvolysis requires shorter period of time compared to pyrolysis, therefore it is possible to process bigger amount of rubber (andrejkov e. et al, 2005). 67 journal of sustainable architecture and civil engineering 2017/1/18 table 1 composition of tyres (raw materials) composition of tyres rubber 36% fillers (carbon black, microsilica) 37% steel and textiles 18% plasticizers (substances added to ensure elasticity and freeze resistance of the product) 3% sulphur 1.3% zinc oxide 1.2% chrome, nickel, lead, cadmium 3.5% materials and methods major and the most important component is rubber obtained from caoutchouc (kalninsh m., 1988). tyre components are given in table 1. two granulometric fractions of the tyres have been used in the experimental part: 5-12mm (fig. 2) and 0.2-1mm (fig. 3). they were prepared using mechanical cutting equipment. fig. 2 rubber crumbs with the size 5-12mm fig. 3 rubber crumbs with the size 0.2-1mm journal of sustainable architecture and civil engineering 2017/1/18 68 pure bitumen without foreign matters and caoutchouc additions is used for tyre dissolution. properties of the bitumen used in the experimental part are given in table 2. rubber crumbs from the recycled tyres constitute 20% ±0.5% from the total weight of the material used in the research aimed at assessing the interaction of bitumen and caoutchouc. amount of the raw materials is given in table 3. rubber crumbs without metal frame were used as they were intended for heating in microwave. all compositions have been mixed during the heating process in order to maintain even heat distribution among various components. due to the high levels of fume the experiments were carried out in the premises with a special ventilation. electric power consumption during the experiment has been measured with the electricity meter. plan of the experiments is given in table 4. table 2 properties of the bitumen table 3 amount of the raw materials used properties measurement units research method value penetration index at the temperature 25oc 0.1 mm en 1426 20-30 softening temperature oc en 1427 ≥ 64 fragility temperature oc en 12593 ≤ -5 paraffin content % en12606-1 ≤ 2.2 dynamic viscosity at the temperature 60oc pa*s astm d 4402 ≥ 5000 inflammation temperature oc en iso 2592 ≥ 240 density 25 oc g/cm3 en iso 15326+a1 1,0 – 1,1 undissolved particle content % m/m astm d 4124 ≥ 18 weight changes after ageing % m/m en 12607-1 ≤ 0.4 temperature increase after ageing oc en 1427 ≤ 8.0 penetration decrease after ageing % en 1426 ≤ 35 number of the experiment series bitumen, g (%) rubber crumbs, g (%) total, g (%) 1.-4. 160g (80%) 40g (20%) 200g (100%) table 4 marking of samples sample number number of the experiment series heating equipment amount of bitumen, % amount of rubber crumbs, % crumb size, mm i 0 100 ii 0 100 iii 1. furnaces 80 20 5-12 iv 1. furnaces 80 20 5-12 v 2. furnaces 80 20 0.2-1 vi 2. furnaces 80 20 0.2-1 vii 3. microwaves 80 20 5-12 viii 3. microwaves 80 20 5-12 ix 4. microwaves 80 20 0.2-1 x 4. microwaves 80 20 0.2-1 69 journal of sustainable architecture and civil engineering 2017/1/18 solvolysis recycling proceeds in two stages: thermal solvolysis and further thermal oxidation with air. heavy oil residues can be used as solvents, such as residues from the oil distillation (gudrons), oxidesed gudrons, etc. the most ration option from the economic point of view would be using the cheapest products, namely, gudrons. as the process takes place under the atmospheric pressure, the solvent should not contain any fractions that melt under the temperature of 360oc (andrejkov e. et al, 2005). fly ash particles and liquid products obtained from the used tyres with the thermal solvolysis serve as modifiers for the bitumen materials (lebena p., 2004). by changing the proportion of rubber crumbs and oil residues as well as conditions of the solvolysis and thermal oxidation it is possible to obtain various types of bitumen with different characteristic curves corresponding to the basic indicators of the existing norms and standards. solvolysis process happens at high temperatures (200-300ºс) or by using special additives (which are usually very expensive) promoting devulcanisation of rubber at lower temperatures. the process results in the rubber-bitumen composite used as a binder for asphalt (amosova i., 2005). to melt the rubber crumbs, the device, which is equal to the modern microwave operating at the microwave frequency 2450 mhz and equipped with the mechanical mixing option and temperature indicator, have been used. according to the literature sources (alekseenko v. et al, 2013) the crumbs melt at the temperature 230±5°с. the initial temperature of all samples was +20±2oc and each composition of the bitumen and used tyre mix has been heated until 230±5oc. it took about 200 minutes to reach the necessary temperature in the conventional electric furnace, while it took only 6-7 minutes in the microwave. then the experiment continued with keeping the samples at the temperature 230±5oc while the rubber crumbs completely melted and incorporated into the bitumen. the rubber crumbs melt in 235-250 minutes in the furnace (fig. 4), while in takes only 18-25 minutes in the microwave. due to the consumption of the electric energy the production costs are significantly higher using the electric furnace compared to the experiments in the microwave. from the obtained information it can be concluded that for melting 0.1 kg of the bitumen and tyre mix 3.2 kwh of the electric energy is used in the electric furnace, while only 0.275 kwh –in the microwave (table 5). result fig. 4 graphic relation of the consumed time (min) and temperature in the experiment series 2 and 4 journal of sustainable architecture and civil engineering 2017/1/18 70 equipment fraction of rubber crumbs, mm time consumed, min electric power consumption, kw*h electric furnace 5-12 222 3.329 electric furnace 0.2-1 206 3.092 microwave 5-12 12 0.300 microwave 0.2-1 11 0.252 by melting the tyres and incorporating them into bitumen the rubber-bitumen composite with the properties depending on the fillers and additives of the tyres is obtained. this material can be used in the road building industry as a binder for the road surface or in the construction industry for the water proofing of the structures. one of the important properties of binder is adhesive property. researchers (somé saannibe ciryle et al, 2012) have investigated table 5 comparison of the consumed time and electric energy for the weight 0.1 kg fig. 5 results of the adhesion tests, mpa fig. 6 proportion of the pulling parts (on bitumen/on concrete surface) and made attempt to quantify the bonding quality between hot bitumen and other material. the bonding properties of bitumen have been test basing on the standard en 15322. to test the adhesive properties of the obtained material, 3 samples of the concrete glued with the bitumen 71 journal of sustainable architecture and civil engineering 2017/1/18 composite material have been prepared for each composition of bitumen. the samples have been processed with the grinding machine and two pieces of concrete were glued with the different compositions of obtained bitumen. each concrete piece has size 40x40x80 mm. concrete specimens were glued by the surfaces with size 40x40 mm. the glued surface of the concrete samples was 1600 mm2. all bitumen compositions and pure bitumen were heated before sealing for improving their fluidity properties. analysis the experiments carried out within this research provide an idea and give a real-life experience about each of the two methods for the tyre recycling with solvolysis. it can be seen from the data included in the table 5 that the processing of rubber crumbs in the microwave provide considerable cost advantage; however, it is related to the significantly higher release of air polluting substances (at least, as far as it can be concluded from the experiments). unfortunately, it was not possible to determine the amount and composition of the substances released into the atmosphere in the form of fume. however, the following observations have been made: 1 during the experiments involving microwave there has been more fume than during the experiments with electric furnace; 2 experiments involving microwave took significantly shorter time than experiments involv-ing microwave. therefore, it is possible to put forward a hypothesis that the total amount of fume can be even bigger using the electric furnace due to total time consumption. the results of the adhesion tests vary; however, it is clear that the adhesive properties of the rubber-bitumen composite used together with the concrete are not lower than those of the bitumen alone (fig. 5). in has been observed that the best adhesive properties are for the rubber-bitumen composite obtained in the microwave (fig. 6). it could be explained with the better melting of rubber and its incorporation into the bitumen. the results of the experiments show that 0.1 kg of the rubber-bitumen composite can be obtained in 11-12 minutes using the microwave, while it takes 230-250 minutes using the furnace. therefore, it can be concluded that by using the microwave it is possible not only to shorten the melting time of the rubber but also to decrease the consumption of the electric energy around 10 times. results of the adhesion tests show that they differ depending on the fraction. during the experiments it was not possible to mix the rubber and bitumen evenly, which could possibly affect the adhesive strength. in general, the rubber-bitumen composite obtained in the microwave showed better results. used tyre recycling with solvolysis showed significant economy of the electric energy using the microwave compared to the conventional electric furnace. it allows reducing co2 in the used tyre recycling industry and obtaining raw materials of a good quality for the production of binder for the road surface or in the road building industry and for the water proofing materials used in various structures in the construction industry. conclusions referencesbaldino noemi, gabriele domenico, lupi francesca r., rossi cesare oliviero, caputo paolino, falvo thomas, rheological effects on bitumen of polyphosphoric acid (ppa) addition, construction and building materials 2013 (40) 397–404. lebena p., “system for dissolving unuseable tires to obtain oils, coal and steel”; 2004 year. kalniņš m.. ”polimēru fizikālā ķīmija”, 1988.gads; [kalninš m., “polymer-phisical chemistry”, 1988]. ortega f.j., navarro f.j., garcía-morales m., mcnally t., thermo-mechanical behaviour and structure of novel bitumen/nanoclay/mdi composites, composites part b 2015(76), 192-200. https://doi.org/10.1016/j. compositesb.2015.02.030 somé saannibe ciryle, gaudefroy vincent, delaunay journal of sustainable architecture and civil engineering 2017/1/18 72 didier, estimation of bonding quality between bitumen and aggregate under asphalt mixture manufacturing condition by thermal contact resistance measurement, international journal of heat and mass transfer, 2012 (55), 6854–6863. urtāne sandra. “riepas ugunskurā!?” 2012.gads; [urtane s., “tires in fire !?”, 2012]. en 15322 bitumen and bituminous binders – framework for specifying cut-back and fluxed bituminous binders, 2013. андрейков е.и., амосова и.с., гриневич н.а., чупахин о.н., статья «утилизация отработанных автомобильных шин с использованием термического сольволиза», химия в интересах устойчивого развития 2005 год (13): 725-729; [andrejkov e., amosova i., grinevich n., chupahin o., article “used automobile tires utilization using termical solvolisys” chemistry for sustainable development interest, 2005] алексеенко в.в., житов р.г., кижняев в.н., митюгин а.в.« новые технологии получения битумо-резиновых композиционных вяжущих»; 2013 год; [alekseenko v., zhitov r., kizhnev v., mitjugin a., “new polymer-modified asphalt binder production technologies”, 2013]. амосова и.с., диссертация «термический сольволиз углей и резины в органических растворителях в отсутствие молекулярного водорода», екатеринбург – 2005 год; [amosova i., “coal and tires termical solvolysis in organic solvent without molecular hydrogen”, ekaterinburg, 2005]. житов р.г., автореферат «получение и свойства полимер-битумных композитов», 2013 год; [zhitov r., autor’s abstract “polymer-bitumen composite properties and it production”, 2013]. папин а.в., игнатова а.ю., макаревич е.а., неведров а.в., «получение композиционного топлива на основе технического углерода пиролиза автошин», 2015 год; [papin a., ignatova a., makarevich e., nevedrov a., “based on tires technical carbonium pyrolysis reaction composite fuel producing”, 2015]. папин а.в., игнатова а.ю., макаревич е.а., «пути утилизации отработаннных шин и анализ возможности использования технического углерода пиролиза отработанных автошин», 2015 год; [papin a., ignatova a., makarevich e. “ways how to utilize used tires, and recycled tires with pyrolysis methode technical carbonium using possibilities analysis”, 2015]. http://www.business-equipment.ru/images/utilizaciya-avtomobilnyh-shin.jpg, (accessed 23 november, 2015) http://www.videsvestis.lv/content.asp?id=41&what=12, (accessed 13 october, 2015) http://ztbo.ru/o-tbo/stati/piroliz/piroliz-shin-i-pokrishek, (accessed 15 october, 2015) aleksandrs korjakins professor riga technical university. institute of materials and structures, department of building materials and products main research area building materials, high efficiency concrete, insulation materials, porous ceramic, lightweight concrete, recycling address kalku st. 1, riga, lv1658, latvia tel. +371 26422442 e-mail : aleksandrs.korjakins@rtu.lv aleksandrs holimenkovs jsc bmgs civil engineer main research area analysis of building structures, recycling and reuse the tyres, building technology address kalku st. 1, riga, lv1658, latvia tel. +371 29873141 e-mail: aleksandrs.holimenkovs@gmail.com about the authors 5 journal of sustainable architecture and civil engineering 2017/4/21 *corresponding author: jurate.kamicaityte@ktu.lt the study of cultural landscapes of central yakutia for the development of scientific tourism received 2017/11/21 accepted after revision 2017/12/28 journal of sustainable architecture and civil engineering vol. 4 / no. 21 / 2017 pp. 5-16 doi 10.5755/j01.sace.21.4.19501 © kaunas university of technology the study of cultural landscapes of central yakutia for the development of scientific tourism jsace 4/21 http://dx.doi.org/10.5755/j01.sace.21.4.19501 viktoriya filippova the institute for humanities research and indigenous studies of the north, russian academy of sciences, siberian branch, petrovskogo st. 1, yakutsk, russia, 677027 antonina savvinova, yurij danilov north-eastern-federal university, institute of natural sciences, department of ecology and geography, kulakovskogo st. 48, yakutsk, russia, 677000 sébastien gadal aix-marseille univ, cnrs, espace umr 7300, univ nice sophia antipolis, avignon uni 13545 aix-en-provence, france jūratė kamičaitytė-virbašienė* kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania in this article authors analyse natural and cultural landscapes for scientific tourism. central yakutia with the unique permafrost landscapes is a rich and large territory of sites of interest for the development of “scientific tourism” for explorers, researchers or eco-natural-tourists. there are three types of scientific tourism relevant for central yakutia: the aim of which is scientific research; the aim of which is practical training and education of students of educational institutions; the aim of which is introducing the history of scientific research, unique natural resources, historical and cultural heritage to a wide range of people. the objects of interest of scientific tourism – landscapes of khangalassky region – are classified according the selected types of scientific tourism using methods of secondary sources analysis and field research. the study showed that scientific tourism on the territory of central yakutia is quite feasible and has great prospects due to the unique landscapes. it can also give impetus for the new scientific discoveries. in one of these new areas the research is being conducted within the framework of the project rsf 15-18-20047, which justifies the application of the concept of identifying the ontological characteristics of the landscapes with the use of linguistic and mental representation of it. the determination and description of cultural landscapes, collection of field materials and mapping of the cultural and landscape zoning of khangalassky region was funded by the rsf (russian science foundation). keywords: yakutia, khangalassky region, landscapes, scientific tourism. journal of sustainable architecture and civil engineering 2017/4/21 6 introduction recently, scientific tourism is considered to be one of the fast-pace developing types of tourism, which continues to play an increasing role in attracting tourists to the undiscovered far corners of the planet. m.a. vinokurov suggests that “scientific and educational tourism is a comparatively new type of international tourism which involves travelling with the aim carrying out scientific research, studying or upgrading professional skills. paleonthological, archeological and limnological and some other types of tourism are known as special types of tourism. additionally, participation in scientific research expeditions, conferences, symposiums is also included into the scientific tourism category.” (vinokurov, 2004, p. 22). scientific tourism can be subdivided into the following types (ereshko f. i., 2006): introductory – natural and anthropogenic objects and samples are shown to tourists and the qualified explanations are given; subsidiary participation tourists take part in scientific and related activities as support personnel, for example participate in restoration work, field research, i.e. independent research of tourists in cooperation with scientific personnel. presently, we are witnessing a new phenomenon congress tourism and the implementation of scientific expeditions and stations which are included into the scope of tourism. generally, using their potential is aimed at discovering new “desolate” routes, at preserving and developing national parks, sanctuaries, reviving water resources and the fishing industry as well as flora and fauna, and, lastly, making prominent the ecological problems of tourism. one of the key factors in such a co-operation has been and still remains to be different scientific institutions and their staff members. the result of the work would be undergoing positive changes of the landscape in accordance with the goals the researcher has set; another result would be the formation of a special cultural landscape type, i.e., scientific landscape (suleymanov, 2014). the territory of yakutia lies in the north-eastern part of the russian federation and occupies 1/5 of its total territory; it is an attractive region in terms of scientific tourism development due to its extreme climatic conditions, vast territory and a unique and diverse landscape. the initial stage of scientific tourism development in yakutia is strongly connected with the study of the territory of yakutia, the arctic in the era of great geographic and scientific discoveries. researchers from russia and all over the world, russian fantasy writers and romanticists made a great contribution to the scientific research of the north. they also helped to raise a romantic interest for adventures connected with survival in the extreme climatic and natural conditions. among these events, the most significant one was the visits made by distinguished scientists and their scientific discoveries. for instance, few people know that during his trip around the world, georg adolf erman visited yakutsk in spring 1829 in order to observe the earth’s magnetic field phenomenon. based on erman’s observations, carl friedrich gauss came up with his own magnetic field theory (obruchev, p.14). r.i. ivanova suggests that the most visited modern scientific tourism areas in the sakha republic (yakutia) are the lena pillars national natural park, the kisilyakh mountains, the diring uryakh paleonthological camp of the prehistoric period, byulyus glacier, the emelyan yaroslavsky yakut state museum of history and culture of the peoples of the north and its affiliated branches, the druzhba museum and sanctuary of history and architecture, the orto doidyu zoo, the mammoth museum, the p.i. melnikov permafrost institute of the siberian division of the russian academy of science, the ytyk khaya ethnographic complex, the mir pipe, a diamond-mining carrier, etc (ivanova, 2012). other interesting objects can be added to the list, namely: _ the batagaika faulting in the verkhoyansky region, which is a unique frost-thaw basin formed as a result of thawing processes; the basin is a kilometer wide and approximately 100 meters deep in some parts. scientists have already proclaimed batagaika one of the main objects in russian and the world suitable for permafrost studies. apart from researchers, tourists have also shown interest in the visiting the basin. soon it may acquire a status of a popular touristic zone. 7 journal of sustainable architecture and civil engineering 2017/4/21 methods _ the mammoth mountain, a unique location of the middle miocene period complex of natural fossils and middle pleistocene period mammal fossils, which is situated on the border of the tatinsky and the tomponsky regions. this area resembles a plateau, about 80 meters in height and it is one of the routes of international geological expeditions. in august 2008, under the leadership of a.v. brushkov, a professor of geological and mineral sciences at msu (moscow state university), russian and international scientists found live microorganisms, the age of which is approximately 15 million years. these microorganisms were discovered in the sand layers of the mammoth mountain and they were previously undiscovered by other scientists. experiments and laboratory studies revealed sensational results – scientists have discovered bacilli which are able to prolong life duration (mamontova gora http://rulandinfo.ru/tours/214/763/?sphrase_id=3791). _ the pleistocene park is the main project of the north-eastern scientific station. the park is located beyond the polar circle in the chersky township of the sakha republic (yakutia). the idea of creating a pleistocene park founded by a russian researcher s.a. zimov was to introduce the preserved species of large fauna with the aim of restoring the soil and landscape typical for the mammoth tundra steppes, which would make it possible to restore a highly productive grass layer and ecosystem that became extinct 10 thousand years ago with the end of the ice age together with the end of the pleistocene period. zimov’s studies on permafrost, greenhouse gas emissions and mammoths attract the attention of many scientists worldwide. _ oymyakon, or the pole of cold is an area which annually attracts scientists who are interested in the special living conditions of the local population in an extreme climate. in addition, there is a lake labynkyr located on the territory of the region, where according to one legends lives a giant animal, more commonly known as the labynkyr devil. in the 60’s and 70’s, several expeditions were held and several touristic groups have visited the labynkyr area; scientific expeditions on finding undiscovered gigantic animals are still held today and attract tourists as well as researchers. thus, it can be clearly seen that yakutia has a significant potential for the development of scientific tourism. the aim of the study is to classify the landscapes of central yakutia (namely khangalassky region) as the objects of scientific tourism and to specify their elements and features important to scientific tourism. classification of landscapes and scientific tourism being potentially highly attractive areas for scientific tourism, natural and cultural landscapes of yakutia are characterized as having unique physical and geographical (permafrost) processes. the only existing specialized institute of permafrost of the siberian division of the russian academy of sciences located in yakutsk makes a significant contribution to the study of centuries-old permafrost layers and unique permafrost landscapes (alases, baidzherakhs, bulgunnyakhos, and yedomas). the institute cooperates with many countries worldwide (china, mongolia, south-korea, germany, canada, usa, japan and france). the institute researchers also take part in international arctic programs, which raise interest among many scientific researchers globally; these programs also promote the development of scientific tourism in yakutia. the institute staff holds research on the study of the process of the permafrost zone evolution under the influence of natural and anthropogenic factors; they also evaluate the temperature and mechanic impact of engineering constructions on the permafrost ground layers; another aspect of the research is to hold fundamental and applied research studies in the area of geological cryology (permafrost studies) including landscape classification. journal of sustainable architecture and civil engineering 2017/4/21 8 presently, the problem of landscape classification remains to be solved due to its high complexity. scientists continue holding research in this area (mamay, 2005). in our opinion, among the classifications of natural and territorial complexes, the most empirically and practically valuable are classifications provided by n.a. solntsev (2001), f.n. milkov (1966), a.g. isachenko (1991), et al. they managed to solve one of the main problems to identify the main units for a classification. such notions as section, class, type, and landscape format became widely-recognized (martsinkevich, 2005). the choice of a classification was in favor of a method suggested by f.n. milkov as a basic one for the studies of yakutian landscape. this classification has a number of advantages: the non-dependency of the taxonomic data in general and of each taxonomic unit in particular, namely – geological and geomorphological as well as biohydroclimatic. this creates a universal classification system for contrasting areas. another advantage of this classification is its correspondence to main approaches in singling out natural and territorial complexes with different permafrost features (dpf) (fedorov, 1991). milkov’s idea on the organization and principles of landscape differentiation are presented in his taxonomic system which takes into account three main areas of natural environment differentiation: regional complexes, typological complexes and paragenetic complexes. regional complexes are genetically unified, territorially complete and unique landscape complexes. typological complexes are morphologically unified, genetically diverse landscape complexes with a discontinuous range. paragenetic complexes include systems of adjacent and genetically connected regional and typological complexes. each range represents an independent selection of units, each used for specific goals: regional complexes are used for zoning; the typological complexes are used for mapping; the paragenetic complexes are used for carrying out a systematic landscape analysis. based on the aspects mentioned above, a.n. fedorov suggested adding one more criterion in the basis of typological zoning that would take into account the permafrost zone layers. this criterion nowadays forms the basis of landscape zoning in yakutia. the principles in the basis of this taxonomic system allow solving the problems of a “horizontal” classification of permafrost landscapes and their mapping more rationally. this system was rearranged in order to hold research in the sphere of permafrost layers development and to evaluate the sustainability level of the permafrost landscapes (landshaftyi yakutii, 2016). the problems of studying the sustainability of permafrost landscapes of yakutia and the population’s adaptation to the landscape and climate changes are the main focus for scientific researchers, tourists and photographers, who are interested in scientific research results in one of the regions of the russian federation with unique and extreme natural and climatic conditions. cultural landscape is an entire complex of ethnic groups’ lifestyle characteristics in specific natural and geographic conditions. the surrounding geographical environment, the time of settlement and territorial development, various fishing and hunting techniques as well as national traditions of the peoples that populated these lands – all these aspects caused a considerable impact on the formation of the cultural landscape. presently, there are very few landscapes remaining which had not experienced a direct or indirect impact of the human activity. in their turn, landscapes, which inevitably were involved in the human activity, play a significant role in forming the consciousness, an aspect which finds its reflection in culture and different social and economic processes. in modern cultural geography, the topic of special organization of cultural landscapes causes many discussions, which is connected with differences in understanding the notion of cultural landscape itself and the various approaches to the study of cultural landscape suggested by russian scholars, namely: y.a. vedenin, v.l. kagansky, b.b. rodoman, v.n. kalutskov, t.m. krasovskaya, m.v. ragulina, r.f. turovsky, m.e. kuleshova, g.a. isachenko, v.a. nikolayev, e.y. kolbovsky, v.a. nizovtsev et al. the methodological aspects of studying ethnocultural landscapes are described in the fundamental research carried out by v.n. kalutskov, y.a. vedenin, t.m. krasovskaya, m.v. ragulina, y.g. simonov et al. (kalutskov, 2011; vedenin, 2004; krasovskaya, 2003; ragulina, 2015; simonov, 1998). 9 journal of sustainable architecture and civil engineering 2017/4/21 results meanwhile, ethnocultural landscapes in russia are not widely-studied, especially in the polyethnic northern territories. in the study of yakutia’s cultural landscape, the republic serving as a bright example of polyethnic territory, researchers mainly focus their attention on the ethnocultural approach due to a great variety of special natural, ethnological, cultural and economic features of yakutian territory. specific aspects of ethnocultural landscape include: ethnic composition, dermic diffusion, culture, history of yakutia’s territorial development, and economic development. these aspects were described by ethnologists, historians, area researchers, and geographers in their fundamental works, to name a few – s.a. tokaryev, v.l. seroshevsky, r.k. maak, g.p. basharin, b.o. dolgikh, i.s. gurvich, a.p. okladnikov, v.a. tugolukov, v.n. ivanov, a.s. parnikova, v.b. ignatyeva, e.n. fyodorova. one of the latest works devoted to the complex study of ethnocultural landscapes of yakutia was written by z.f. degteva (degteva, 2017). the study of yakutia’s cultural landscape using an interdisciplinary approach was first suggested by the staff members of the institute for humanities research and problems of the indigenous people of the north. they singled out the differences and similarities in the formation and functioning of the rural cultural landscape, which developed in the last 30 years of the last century and was existing in the first few decades of the 21st century. they accomplished this using local examples of yakutian villages of the central and viluy regions of yakutia (vinokurova, 2014). both natural and cultural landscapes of yakutia are interesting objects for the development of tourism in general and scientific tourism in particular. however, unfortunately, it must be stated that there are no existing touristic infrastructures for attracting tourists closely located to the unique landscapes in the hidden corners of yakutia. summing up we have decided to classify natural and cultural landscapes of khangalassky region in central yakutia and clear out their elements and components as objects of interest of scientific tourism performing analysis of secondary sources and field research. the landscapes of khangalassky region for scientific tourism landscape resources an example of the most convenient area from the point of view of providing the tourist infrastructure and the availability of tourist resources necessary for the development of scientific tourism is the territory of the khangalassky region, which has unique resources for the development of scientific tourism: a variety of natural landscapes, the presence of ethnographically interesting regions, interesting historical complexes, architectural monuments, archaeological sites, centres of various national folk crafts, as well as a developed system of scientific research in broad areas (fig. 1). before, to classify natural and cultural landscapes and their elements and components in order to develop scientific tourism in the khangalassky region, we will consider separately the existing classifications of natural landscapes, as well as the cultural elements and components of the landscapes of the area. the territory of the khangalassky region can serve as an example of a convenient touristic area in terms of touristic infrastructure and resources that it contains, which are necessary for the development of scientific tourism as both a large-scale activity and as an exclusive type of activity. the territory of the khangalassky region has a great natural potential for the development of scientific tourism. one of the main natural resources of the region is the lena pillars natural park, which was included into the unesco list of world heritage in 2012. the administration of the park takes an active part in creating and promoting touristic products on the territory of the park; it also closely cooperates with scientific institutions to hold scientific paleontological, limnological, and geocryolithic research. since the time of its establishment, there have been scientific studies held by russian and international scientists, students and natural conservation organizations. journal of sustainable architecture and civil engineering 2017/4/21 10 landscape geographic and geologic structure the khangalassky region is located in the central part of yakutia and it borders with three landscape provinces: the lena-amginsky alasnaya plain landscape, the lena-amginsky sand landscape, and lena-aldansky karst landscape (fedorov, 1991). this fact defines the relatively wide range of conditions for the functioning and development of various typological natural and territorial complexes (ntc) in terms of their genesis and structure. upland area types differ from other types by the discontinuity of the lithogenic basis and it is subdivided into tow subtypes. the karst subtype of the upland area is represented by fruticulosey as well as combinations of fruticulosey and mossy larch areas, with mixtures of spruce trees which are mainly present in the eluvium of the cambrian soil. the sandy upland subtype is mostly spread on the eluvium of the jurassic period with a lichen and fruticulosey as well as fruticulosey and pine tree forests. bottomland type of landscape with alluvium sediment is occupied by the valley forests, dwarf birches and willow shrubs. slope type of landscape on carbonate formations of the cambrian period is mainly represented by the larch, fruticulose and alder forest areas. these forests located on the slopes of warm expositions are gradually replaced by steppe-like plains and fruticulose-like pine trees. territories with areas of increasing external agencies and the revelation of cambrian formations are presented by flora growing on rocky areas (plan…, 2014). the inter-plain type of areas with sabulous clay-loam formations are covered with fruticulose and pleurocarpous moss larch forests and it can be seen in the eastern area of the park. sand bed type of landscape is presented in the medium-altitude sand terraces of the lena river on the khangalassky territory of the natural park with fruticulose and lichen-fruticulose and fruticulose-lichen a c d b fig.1 landscapes of khangalassky region: typical natural landscapes (a, c), valley of lena river (b), centre of national festivals (d) (photos made by j. kamičaitytėvirbašienė (b,c), a.n. savvinova (a, d), 2016) 11 journal of sustainable architecture and civil engineering 2017/4/21 pine trees. within the area of the low-altitude terrace type of landscape on the aluvium sedements there are valley forests, willows and plains. apart from studying the landscape, the permafrost institute in cooperation with the oxford university (great britain) studied the permafrost layer condition by dating the shelf-stones in the karst caves in 2013. the natural objects which are of interest to scientific tourism in khangalassky region are paleontological, geological, limnological, geocryologic objects. an example of paleontological objects is the lena pillars on the unesco world heritage list, located on the right bank of the river lena, with a length of 40 km, which represents the numerous remains of the destruction of bedrocks of lower cambrian limestone with an age of 530 million years, where unique fossils are found. locations of remains of fossil organisms that have not undergone any significant changes, where whole fragments of extinct animals are preserved in the fossil state, are of great importance for the world science, in particular for studying the cambrian evolutionary explosion. now in the world paleontological tourism when people visit places of finds and scientific institutions which are engaged in their studying gains popularity. scientific works aimed at revealing the paleontological potential of the lena pillars natural park will help to establish the republic as the paleontological center of russia for studying the cambrian period. geological monuments are scientifically valuable objects or landscapes on which it is possible to conduct research of objects revealing tectonic features of the region and geomorphological observations. these include the buotama rocks, which are located below the mouth of the river. hariya-uryakh. the buotama river flows in the vicinity of picturesque cliffs, not inferior in beauty to the famous lena pillars. particularly impressive are the colourful outcrops of marls, limestones, dolomites dating back to the cambrian period (400-500 million years ago). in the same group can be attributed sinsky poles, not as high as lensky ones. they rise above the river a little more than 100 meters. however, they leave no less impression of their grandiosity, especially where the vertical wall goes directly under the rapid flow of the river. limnological studies for the inclusion of lakes in the list of scientific tourism sites are conducted on many lakes of the khangalassky region. however, the most interesting from the point of view of scientific study is lake borulaakh, located on the watershed of the river lena and the river buotama. its uniqueness lies in the fact that in winter, usually in december, the water level drops sharply by 8-10 meters. thus, the lake is almost completely shallow. the conducted studies confirmed the presence of active karst processes under the bottom of lake borulaakh and in the adjacent territory, as evidenced by the descent of water with the collapse of the lake ice cover and the funnel-shaped depressions of the lake bottom. dynamics of the water mode of the karst lake borulaakh is the proof that permafrost karst – a unique natural phenomenon, and the lake is only a part of the large-scale karst system developing in carbonate breeds of the cambrian in the territory of the natural park “lena pillars”. in 2015 and 2016, an expedition team of the yakut division of the russian geographic society in the sakha republic (yakutia) held a scientific trip to the borulakh lake located on the territory of the natural park in order to study the unique whistling karst lake, in which the water runs out into the soil through funnels during the winter period and recommended its inclusion in the routes of scientific tours. to the unique geocryological objects of the region can be attributed tukulans (from evenki “tukala” sand, “tukalan” sandy massif or dune). these are typical sand formations of cryolithozone with unique vegetation, which are large active dynamic waved sand massifs, the development of which is associated with geographic medium. most researchers believe that the tukulans are a remnant of an unusual, peculiar desert that once occupied huge areas, as adjacent to modern journal of sustainable architecture and civil engineering 2017/4/21 12 tukulans, there are vast fields of smoothed dunes already completely covered with taiga. the three stages of the tukulans history are known: accumulation of sands as a result of their deposition by rivers, transfer and redeposition by the wind, fixation of sandy massifs by vegetation. dune complex are widely distributed in the basins of the vilyuy and the lena rivers and were described by the researches in the 19th century. on the territory of the khangalassky region there are two tukulans. “kysyl elesin”, located 8 kilometres from the mouth of the buotama river a dune formed from the sand blown by prevailing winds from the slope of the terrace. tukulan “saamis kumaga” (length about 5 kilometres; the widest part about 850-900 meters) consists of ridges and hollows shafts-blowing, having a depth of 20 meters. in some basins there is rather lush vegetation – pine trees at the age of 30-35 years, with a height of 12-14 meters, thickets of rosehip and grass. the combination of geological and geomorphological data, in particular the study of fossil pollen and spores, as well as discoveries of mammoths, bison, and other extinct mammals, indicate that the dune complex is a relic of the so-called cold deserts. that is why these unique natural objects are of interest for scientific tourism. all of the natural objects mentioned above are located on the territory of natural park “lena pillars” and are represented as the unique object for research. annually, teams of employees from the institute of biological problems of the cryolithozone of the siberian division of the russian academy of sciences hold research on the territory of the park. academic staff members and students of the north-eastern federal university (nefu) also hold research there (lenskie stolbyi http://lenapillars.ru/posts/view.aspx?id=150). researchers from the permafrost institute of the siberian division of the russian academy of sciences also hold scientific research of the permafrost layers and landscapes in the lena pillars natural park. the landscape study approach allows to establish objectively and complexly the special features of the geological, geomorphological, botanic and other natural monuments using the data of historical development, the place and role in the modern natural environment, and the evolution of the natural objects on this territory. geographical features and natural resources create a unique background for the cultural and architectural objects, events that carry historical significance, and are the attraction for tourists. historical and cultural potential is an important competitive advantage of the khangalassky region and is based on a heritage that includes a social cultural environment with established canons and traditions, features of activities both economic and household. there are many objects of cultural heritage in the territory of this region; their uniqueness is defined by a prevalence of archaeological and ethnic and cultural objects which perform a very important social function: archaeological materials are used in the region’s local museum expositions. traditional festivals are held annually. the historical heritage of the post stations of the irkutsk-yakutsk post route is well-preserved and is used in forming the touristic products (kontseptsiya..., 2014). the anthropogenic objects: tangible and intangible cultural heritage the historical and cultural resources include architectural monuments, archaeological excavation sites, museum complexes, monumental architecture objects, etc. taking this into consideration, we singled out the following groups of such resources analysing the cultural landscapes of the khangalassky region: 1 historical monuments which include archaeological monuments (ancient nomad camp-sites). the objects are represented by diring uryakh, an ancient nomad campsite; petroglyphs and runic signs near the bulgunyakhtakh village on the elansky pillars territory; kullaty area, where the tygyn darkhan (a powerful ancestor of the khangalassky region yakuts) family residence was located; tit ebye area, the place where munyan darkhan died and where tygyn darkhan was born; the edey village (which can reveal interesting areas and legends connected with tygyn darkhan); 13 journal of sustainable architecture and civil engineering 2017/4/21 2 civil and cultural architecture monuments include a list of civil and cultural architecture ob-jects, which is compiled by the ministry of culture and spiritual development of the sakha republic (yakutia) and is officially called “the objects of cultural heritage and religious value”. this group includes separate buildings and building ensembles which belong to the category of civil and cultural architecture and monumental art, objects of monumental architecture (memorials, sculpture objects, etc.). such examples include: the samartai open-air architectural museum complex (historical and cultural monuments: kachikatskaya nikolayevskaya church (1892), grain dryer, hexagon-shaped house babaryna (18th century), the rich landowner kirill’s shed (19th century), a traditional summer dwelling balagan (18th century)); 3 social and cultural objects are objects of a cultural or education value; they are objects of cultural heritage. this group includes works of art, traditional forms of art, the entire scope of the traditional or national culture, the language, cuisine, traditions and customs. social and cultural objects include museums, expositions, art galleries, theatres, concert halls, cultural halls (information..., 2017). the main objects, listed in this group are represented by the following examples: an archive library of mikhail nikolaev, the first president of the sakha republic (yakutia); a ceremonial complex for holding the national ysyakh erkeni holiday on the territory of the orto doidyu touristic complex; municipal cultural institution the g.v. ksenofontov khangalassky region local lore museum; the naum zasimov khangalaskaya art gallery; a postman’s courtyard, a postman’s household museum (museum, outdoor buildings, shed, a horse stable, a smithery, etc.). proposal of landscape typology for scientific tourism on the basis of the analysis of spatial differentiation of natural landscape and historical and cultural objects of the khangalassky region, cultural landscape areas with proposed types of scientific tourism are identified. as a result of cultural and landscape zoning within the boundaries of the study area, five regions were identified that have the following characteristics (fig. 2): 1 : 2 500 000 fig. 2 cultural and landscape zoning of khangalassky region (made by v.v. filippova, a.n. savvinova, 2017) journal of sustainable architecture and civil engineering 2017/4/21 14 i. buotama cultural and landscape area is located within the boundaries of the national nature park “lenskie stolby”. the landscapes of this region are represented by the slope type of terrain on which the lena and buotama pillars and rocks are located. in the area of sloping terrain and prisklonovoe areas of the upland type there is located sandy desert – dune complex samys kumaga, kysyl elesin. the greater part of this territory is not suitable for the population, but the small-valley type of terrain is suitable for housing, as evidenced by the ancient settlement deering-yuryakh. in view of the limited visits to the territory of the natural park in this cultural and landscape area, it is possible to conduct scientific tourism for the purpose of professional research and educational purposes. the presence of such objects as deering-yuryakh and lake borulah allows to conduct excursions for acquaintance with the uniqueness of natural complexes for a wide range of people. ii. the cultural and landscape district “erkeeni” is located on the same valley of the river lena, between tabaginskiy cape in the north and the city of pokrovsk in the south. the presence of low-terraced and small-valley types of terrain served to the fact that this valley is one of the three anciently inhabited valleys in central yakutia. this cultural and landscape area in ancient times was inhabited by the yakut hangalassian clans and this valley is considered the residence of the progenitor of the yakuts omogoy bai. there is an archaeological monument of kullata dating back to the early bronze age or the late neolithic. this region is currently populated by the yakut population, and the majority of the population of the khangalassky district lives in this valley. at present, the tourist complex “orto-dojdu” is being formed here, which combines a ritual complex for the national holiday “ysyakh erkeeni”, a zoo, a shooting club, a sports and entertainment complex “tekhtur”. the presence of many natural, sacral and historical, and cultural sites allows us to conduct professional research here, organize tourism for educational purposes, organize excursions for acquaintance with the historical and cultural heritage of the sakha people. visiting the northernmost zoo will allow you to familiarize yourself with the uniqueness of natural complexes of the area. iii. the cultural and landscape area “samartai” is located partly on the same valley of the right bank of the river lena and in the interfluve of the luteng-menda rivers. this area is the only populated area on the right bank of lena river. all settlements are located on the high terraces type of terrain (modern valley of large rivers). the presence in the territory of this cultural landscape of historical and architectural monuments from the 18th-19th centuries allowed the creation of the ethnographic museum “samartai” in 1991, allowing to conduct historical and cultural and agrarian-historical excursions. due to the presence of valley-accumulative (ice-covered) mid-taiga with continuous permafrost rocks, there are such unique objects as ice buluus and waterfall kuruluur where tourists can get acquainted with the uniqueness of natural complexes. iv. the riverscape yamshchitsky cultural and landscape area extends along the left bank of lena river from the village eden to the village bulgunnaytakh and occupies the territory on which the main postal route from irkutsk to yakutsk passed previously. the settlements of this region were laid down mainly as yamschitsky postal stations. unlike in other cultural and landscape areas, the descendants of the cossacks and coachmen, who were engaged in protection and transport, lived in this area. their economic activity and impact on the surrounding landscape were very specific. the presence of historical and cultural monuments of the russian population allows us to conduct historical, cultural, agrarian-historical and ethnographic excursions here. v. sinsky cultural and landscape area is located in the valley of the river blue and unlike the other above-mentioned cultural and landscape areas is uninhabited. the slope type of terrain and the denudation-remnant middle taiga of continuous perennial-frozen rocks contributed to the formation of the sinsky pillars, which are a natural monument of the republic of sakha (yakutia). the sinsky pillars are not inferior in their beauty to the famous lena pillars and can attract tourists interested in unique natural complexes. the conducted research shows that the main specialized types of scientific tourism that can be developed in the territory of khangalassky region are the following: tourism for the purpose of scientific research, tourism for educational purposes, tourism for the acquaintance with the unique15 journal of sustainable architecture and civil engineering 2017/4/21 references ness of natural complexes, and tourism for the acquaintance with historical and cultural heritage for a wide range of people. natural landscapes and the objects of historical and cultural heritage of the khangalassky region are the basis for the development of scientific tourism. however, we have to state that these areas lack the necessary infrastructure, which is one of the main factors for the socio-economically and ecologically effective development of scientific tourism. recognition of these objects as potential areas of scientific tourism and the creation of the necessary infrastructure will help to form the foundations for a new and promising tourist destination and increase the tourist flow in the region. in general, the selected cultural and landscape areas reflect the spatial natural, ethno-cultural and historical-cultural features of certain parts of the khangalassky district and are not final. further, in the process of this zoning, it is possible to include the socio-economic and economic factors of the khangalassky district. this aspect will enable the use of cultural and landscape zoning for the purposes spatial planning. conclusions degteva zh.f. prostranstvennaya organizatsiya etnokulturnyih landshaftov yakutii. [spatial organization of ethno-cultural landscapes of yakutia]. dissertatsiya na soiskanie uchyonoy stepeni kandidata geograficheskih nauk: spetsialnost 25.00.24 – ekonomicheskaya, sotsialnaya, politicheskaya i rekreatsionnaya geografiya. smolensk, 2017. ereshko f.i. nauchnyiy turizm tsel i sredstvo progressa v razvitii regionov [scientific tourism — the purpose and means of progress in development of the regions] // http://archiv.council.gov.ru/files/journalsf/item/20061107123724.pdf fedorov, a.n. merzlotnyie landshaftyi yakutii: metodika vyideleniya i voprosyi kartografirovaniya [permafrost landscapes of yakutia: methods and mapping]. / a.n. fedorov. – yakutsk: institut merzlotovedeniya so an sssr, 1991. – 140 s isachenko, a.g. landshaftovedenie i fiziko-geograficheskoe rayonirovanie [landscape science and physical-geographical zoning]. / a.g. isachenko. – m.: «vyisshaya shkola», 1991 – 366 s. ivanova r.n. soderzhanie i ob’ektyi nauchnogo turizma v yakutii [the contents and objects of scientific tourism in yakutia] // vestnik severo-vostochnogo federalnogo universiteta im. m.k. ammosova. 2012. tom. 9. #2. s. 73-77. kalutskov v.n. etnokulturnoe landshaftovedenie. m.: geograficheskiy fakultet mgu, 2011. – 112 s. kulturnyiy landshaft: teoreticheskie i regionalnyie issledovaniya. tretiy yubileynyiy vyipusk trudov seminara «kulturnyiy landshaft» // otv. red. v. n. kalutskov, t. m. krasovskaya. — m.: izd-vo mosk. un-ta, 2003. kulturnyiy landshaft kak ob’ekt naslediya / pod red. yu. a. vedenina, m. e. kuleshovoy. — m.: institut naslediya; spb.: dmitriy bulanin, 2004. — 620 s. kontseptsiya razvitiya turizma v mr «hangalasskiy ulus» respubliki saha (yakutiya) do 2025 g. [the concept of tourism development in khangalassky ulus of the sakha republic (yakutia) up to 2025]yakutsk, 2014. landshaftyi yakutii: monografiya [landscapes of yakutia] / [yu.g. danilov i dr.]; otv.red. yu.g. danilov. – yakutsk: izdatelskiy dom svfu, 2016. 86 s. lenskie stolbyi [lena pillars] http://lenapillars.ru/ posts/view.aspx?id=150 mamay, i.i. dinamika i funktsionirovanie landshaftov [dynamics and functioning of landscapes] / i.i. mamay. – m.: izd-vo mosk. un-ta, 2005. – 138 s. mamontova gora [mamontova mountain] http://rulandinfo.ru/tours/214/763/?sphrase_id=3791 martsinkevich, g.i. landshaftovedenie [landscape science] / g.i. martsinkevich. – mn.: bgu, 2005. – 200 s.: il. milkov, f.n. landshaftnaya geografiya i voprosyi praktiki. [landscape’s geography and practice issues] / f.n. milkov. – m.: myisl, 1966. – 156 s. obruchev v.a. istoriya geologicheskogo issledovaniya sibiri [history of geological exploration of siberia]. l.: izd-vo an sssr, 1933. 230 s. plan upravleniya prirodnogo parka lenskie stolbyi na 2014 [the management plan of the nature park “lena pillars”] https://minpriroda.sakha.gov.ru/uploads/ ckfinder/userfiles/files/25%2c11%2c13-1.doc ragulina m.v. kulturnyiy landshaft: integralnyiy vzglyad. ulyanovsk: zebra, 2015. — 147 s. simonov yu.g. kulturnyiy landshaft kak ob’ekt geograficheskogo analiza // kulturnyiy landshaft: voprosyi teorii i metodologii issledovaniy. moskva-smolensk: sgu, 1998. s. 34-44. solntsev n.a. uchenie o landshafte: izbrannyie trudyi [teaching of landscape: selected works] / n.a. solntsev; mgu im. m.v. lomonosova, geogr. fak. m.: izdvo mgu, 2001. 383 s.: il. 56. journal of sustainable architecture and civil engineering 2017/4/21 16 about the authors suleymanov a.a. formirovanie nauchnogo landshafta selskih rayonov yakutii v hh v. [the formation of the scientific landscape in rural areas of yakutia in the twentieth century] // teoriya i praktika obschestvennogo razvitiya. 2014. #16. – elektronnyiy dostup: http://teoria-practica.ru/rus/files/arhiv_zhurnala/2014/16/history/suleymanov.pdf vinokurov m.a. chto takoe turizm? [what is tourism?] // izvestiya irkutskoy gosudarstvennoy ekonomicheskoy akademii. 2004. -# 3. s. 19-24. vinokurova l.i., filippova v.v., sannikova ya.m. selskiy kulturnyiy landshaft yakutii: opyit mezhdistsiplinarnogo polevogo proekta [the rural cultural landscape of yakutia: experience of an interdisciplinary field project] // severo-vostochnyiy gumanitarnyiy vestnik.– 2014.– #2.– s.17-24. viktoriya viktorovna filippova senior researcher the institute for humanities research and indigenous studies of the north, siberian branch of the russian academy of sciences, russian federation main research area history, historical geography, gis technology, climate change, demography and settlement of indigenous people, traditional nature use address petrovskogo st. 1, yakutsk, russia, 677027 tel. +79627354796 e-mail: filippovav@mail.ru antonina nikolaevna savvinova associate professor m.k. ammosov north-eastern federal university, institute of natural sciences, department of ecology and geography main research area human geography, gis, remote sensing traditional nature use of indigenous peoples address kulakovskogo st. 48, yakutsk, russia, 677000 tel. +79142368813 e-mail: sava_73@mail.ru kamičaitytė-virbašienė professor kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism main research area landscape visual quality analysis, evaluation and regulation, methods of planned activity or object visual impact assessment, analysis of social preferences evaluating landscape visual quality and use of the analysis results in territory planning, evaluation of the potential of urban structures, research of cityscape identity, expression of sustainable development conception in architecture, landscape architecture, town and territory planning address studentu st. 48, lt-51367 kaunas, lithuania tel. +37061477082 e-mail: jurate.kamicaityte@ktu.lt yuri georgievich danilov professor m.k. ammosov northeastern federal university, institute of natural sciences, department of ecology and geography main research area physical geography, landscape science, climatology address kulakovskogo st. 48, yakutsk, russia, 677000 tel. +79142225104 e-mail: dan57sakha@mail.ru sébastien gadal professor aix-marseille université, cnrs espace umr 7300 main research area remote sensing, gis, spatial analysis, urban studies, territorial development address espace (umr 7300) cnrs / aix-marseille university, technopole de l’environnement arbois méditerranée, avenue louis philibert bp 80 bâtiment laennec, hall c, 13545 aix-en-provence cedex 04, france tel. +33698983040 e-mail: sebastien.gadal@univ-amu.fr 53 journal of sustainable architecture and civil engineering 2020/1/26 *corresponding author: mindaugas.dauksys@ktu.lt research on installation technologies of retaining walls with ground anchors received 2019/06/30 accepted after revision 2019/11/19 journal of sustainable architecture and civil engineering vol. 1 / no. 26 / 2020 pp. 53-64 doi 10.5755/j01.sace.26.1.21540 research on installation technologies of retaining walls with ground anchors jsace 1/26 http://dx.doi.org/10.5755/j01.sace.26.1.21540 mindaugas žagarinskas uab “projektana”, chemijos str. 23d, lt-51331 kaunas, lithuania mindaugas daukšys*, jūratė mockienė kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania introduction with increasing level of urbanization, new buildings are erected in close proximity to existing buildings or quite close to site boundaries. such practice affects the complexity of retaining wall installation technology. when a retaining wall is installed close to an existing building, a street or a steep slope, the stability of the wall has to be ensured first. there are cases when a retaining wall has to be strengthened by creating a permanent or temporary support, i.e. by installing ground anchors. according to literature analysis, the major problem is that a profile stops without reaching its designed depth (van baars). merifield et al. distinguish three major types of anchors: circular, square and rectangular. they emphasise that anchor surface unevenness does not impact anchor resistance. according to nagar, most frequently anchors disintegrate due to excessive tensile strength of the anchor. the increase of this force is related to tensile strength measured in anchor testing. in this paper, three types of retaining walls with ground anchors are considered: pile wall, berlin wall, and sheet piling with excavation depth of 6 m. the conditions are selected as follow: when walls are installed in clay soils, sandy soils, sandy soils at high groundwater levels, and when the wall is installed next to the building. mechanical resistance and stability of construction incline are calculated by means of geo5 software. a survey was designed basing on the calculation results and the selected evaluation criteria. in the survey geotechnical engineers rated 18 different cases. the relevance of criteria is determined by employing the entropy method after the primary results of the survey are summarised; afterwards a multiple criteria decision analysis carried out using the utility function. the multi-criteria assessment results indicate the most rational type of a retaining wall for the chosen conditions. this article is based on master thesis topic “research on installation technologies of retaining walls with ground anchors”. keywords: ground anchors, retaining wall, entropy method, multi-criteria assessment,survey research. ordinary retaining walls are seldom used nowadays. increasing urban density levels lead to the construction of new buildings next to the existing foundation or very close to the site boundaries. such trends of urban planning influence the complexity of retaining wall construction. when a retaining wall is installed close to an existing building, a street or a steep slope, the stability of the wall has to be ensured first. supporting walls from the ground surface are erected to provide the required stability. there are cases when a retaining wall has to be strengthened by creating a permanent or temporary support, i.e. by installing ground anchors. the selection of the retaining wall type and its strength depends on the existing geological condijournal of sustainable architecture and civil engineering 2020/1/26 54 tions. it might be difficult to drive or hammer elements into hard or dense soils. sheet pile walls are most often used to retain the movement of water or soil. sheet piling technology is described in aarsleff 2016a. the capacity of the sheet pile to withstand different forces depends not only on the soil into which the sheet pile is driven but also on the characteristics of the element’s cross-section. sheet pile walls may have the length of 31 meter or even up to 33 meters in the case of h-type walls(katkevicius and baublys 2008). byfield and mawer (2004) argue that interlocked sheet piles form a solid wall. u-elements have locks on the neutral axis, which corresponds with the maximum shear stress; therefore, the joints must be welded to increase the wall’s retaining strength. welded joints increase the resistance to the bending moment up to three times compared to the load bearing strength of a single element. the locks are filled with various synthetic waterproofing materials to ensure the waterproofing capacity of the retaining wall. first of all, the behaviour of steel in different corrosive environments must be examined in order to extend the service life of the wall with appropriately selected cross-section and required protective measures. in practice, two sides of the steel wall are often exposed to different media and thus detailed studies are necessary to ensure the maximum protection (amph 2008). researcher r.w. investigated into the effect of ground water on the retaining wall in different cases: at the same water level on both sides of the wall and at a lower water level on one side of the wall. different water levels and their effect on the retaining wall must be examined for marine structures. the part of the wall, which is closer to the sea bottom, is exposed to corrosion the least, approx. 0.012 mm per year. no severe corrosion occurs in the permanent submersion level either, where the wall is exposed to clean water with the surface of the water covered by a layer of marine flora. the most severe corrosion occurs in tide water conditions or on the surface water level due to a frequent change of corrosive factors (kreišmantas 2016). van baars (2004) argues that in cases when sheet piles are driven by using vibratory technique, the conditions of the soil must be carefully examined in order to select the vibratory hammer with appropriate characteristics. vibratory hammers can be used only for driving sheet piles in weak soils, i.e. soft clays, silt or peat, also in sand permeated with water and hawing a low modulus of elasticity. different problems occur when sheet piling is installed by means of vibratory techniques. van baars (2004) highlights a problem when the pile ceases penetrating the soil before the design depth is reached. the article discusses three main equations, one taken from cur, another from eau, and the third equation is proposed by the author basing on the vibdrive modelling results. cur are dutch compliance standards. this method lacks one very important factor, namely the ground conditions. supporting walls are complex and expensive structures and the engineers designing them must have good knowledge in geotechnical engineering. dedicated computer programmes are used to design these structures. these computer programmes are usedto assess all conditions and select the most rational alternative of the structure within the estimated cost of materials. the required amount of reinforcing bars is one of the key characteristics. the amount of reinforcing bars in retaining walls is usually big and even very big because the structure must bear the ground load, big transverse loads and bending moment caused by other factors. however, the poles of the retaining wall are affected only from one side. therefore, the strain in the cross section is always the same. it means that the strained and compressed zone does not change its position. reinforcement tendons are required to resist the tensile stress and there is no need to use reinforcement tendons of big cross section on the side where it is not necessary. reinforcement tendon installation technology is described in aarsleff 2016. gil-martin et al. (2010) review the optimisation of pile wall reinforcement. the authors argue that the flexural strength of the pile’s cross-section increases when the reinforcement of the tension 55 journal of sustainable architecture and civil engineering 2020/1/26 zone is strengthened, and reinforcement of the compressed zone remains unchanged. this is evidenced by iteration diagrams. the flexural strength of the cross-section increases significantly when the number of reinforcement tendons is increased from 1 to 10. the ground anchor is composed of pre-stressed steel tendon and injected cementitious mortar. the anchor transfers the loads to the ground through the friction between the anchor and the surrounding soil. the injected cementitious mortar provides the support to the tensioned steel tendon. merifiels et al (2003) distinguished three types of anchors: round, square and rectangular. the authors note that the roughness of round, square and rectangular anchors has no significant effect on anchor’s resistance. the analysis of reasons for anchor damage reveals several major conditions leading to anchor damage. according to nagar (2010), the most common reason for anchor failure is the excessive tensile force. the increase of this force is related to tensile strains applied in pre-tensioning. it is important to test not only the maximum load that the anchor can bear but also the load that causes the cracking of fine-grained concrete. concrete cracking leads to the corrosion of the steel tendon. steel tendons in permanent anchors must be protected from corrosion by the coat of anti-corrosive material, which must remain intact throughout the designed service life of the anchor. alternatively, anchor tendons may have two protective barriers. resins can be used as one of the permanent anti-corrosive barriers, provided they are intact, protected and not over-pressed. the resin can be injected or coated in 5 mm layer during the pretensioning (lst en 1537). if the design provides that the load from retaining walls will be transferred to other structures, installation of permanent anchors is not required because the load will be transferred to constructed floors. in such cases temporary anchors are installed and cut off after the floor is constructed. in many cases such a solution saves retaining wall building costs (konstantakos 2010). the aim of this work is to evaluate the effect of existing geological soil conditions on retaining wall installation technologies with temporary ground anchors. methods several variants of geological soil conditions of the were selected for the evaluation of retaining walls with ground anchors. the first variant was sticky clay soil and the second variant was granular sandy soil with a high level of ground water. geological cross-section diagrams were used for the computation. parameters of sticky clay soil and granular sandy soil are presented in table 1, 2. table 1 parameters of sticky clay soil parameters poured soil striped clay, hard plastic sandy, clayey moraine dust sandy, clayey moraine dust, hard unit weight, kn/m3 18.00 18.10 19.90 22.10 stress-state effective effective effective effective angle of internal friction, ° 25.00 11.00 24.00 35.00 cohesion of soil, kpa 0.00 32.00 13.00 63.00 angle of friction struc.-soil, ° 17.00 7.00 16.00 17.00 soil cohesionless cohesive cohesive cohesive poisson’s ratio 0.35 0.35 0.35 0.35 deformation modulus, mpa 5.00 9.00 18.00 325.00 saturated unit weight, kn/m3 20.00 18.50 20.50 22.50 pattern marking in computation scheme 1 (4) 2 3 5 marking in computation scheme 1 (4) 2 3 5 marking in computation scheme 1 (4) 2 3 5 marking in computation scheme 1 (4) 2 3 5 marking in computation scheme 1 (4) 2 3 5 journal of sustainable architecture and civil engineering 2020/1/26 56 investigation conditions: retaining wall with temporary ground anchors driven to 6-meter depth from the top, the load received from the existing building is 200 kn/m2, the foundation of the existing building is 1 meter wide, the distance between the central axis of the foundation and the retaining wall is 1.5 m. wall footing was chosen as a foundation type for the research. temporary ground anchors are necessary to take over a huge tensile strength to supporting base layers for a limited period of time (< 2 years). a temporary ground anchor consists of an injected stem, a stringer with a free part and an anchor. external boring diameter of temporary ground anchors is 133 mm. anchors are bored by a spiral drill in protective tubes with air blow. when a hole is made cement mortar is poured, later a stringer is installed. anchor stem is injected in the ground by mortar which is pressed by high pressure through a distracted protective tube. in 12 hours a following anchor injection is made. after 7 days, the anchor is tested and compressed. anchors supporting table 2 parameters of granular sandy soil parameters primer soil gravel sand gravel sand 12 fine sand medium rough sand unit weight, kn/m3 18.00 19.10 19.30 17.00 17.20 stress-state effective effective effective effective effective angle of internal friction, ° 25.00 41.00 44.00 43.00 42.00 cohesion of soil, kpa 0.00 0.00 0.00 0.00 0.00 angle of friction struc.-soil, °and compressed. 16.00 17.00 17.00 17.00 17.00 soil cohesionless cohesionless cohesionless cohesionless cohesionless poisson’s ratio 0.35 0.35 0.35 0.35 0.35 deformation modulus, mpa 3.50 53.30 79.00 85.60 80.60 saturated unit weight, kn/m3 20.00 21.00 21.00 19.00 19.00 pattern angle of internal friction, ° 25.00 41.00 44.00 43.00 42.00 cohesion of soil, kpa 0.00 0.00 0.00 0.00 0.00 angle of friction struc.-soil, °and compressed. 16.00 17.00 17.00 17.00 17.00 soil cohesionless cohesionless cohesionless cohesionless cohesionless poisson's ratio 0.35 0.35 0.35 0.35 0.35 deformation modulus, mpa 3.50 53.30 79.00 85.60 80.60 saturated unit weight, kn/m3 20.00 21.00 21.00 19.00 19.00 pattern marking in computation scheme 1 2 3 (5) 4 (7) 6 (8) (9) investigation conditions: retaining wall with temporary ground anchors driven to 6-meter depth from the top, the load received from the existing building is 200 kn/m2, the foundation of the existing building is 1 meter wide, the distance between the central axis of the foundation and the retaining wall is 1.5 m. wall footing was chosen as a foundation type for the research. temporary ground anchors are necessary to take over a huge tensile strength to supporting base layers for a limited period of time (< 2 years). a temporary ground anchor consists of an injected stem, a stringer with a free part and an anchor. external boring diameter of temporary ground anchors is 133 mm. anchors are bored by a spiral drill in protective tubes with air blow. when a hole is made cement mortar is poured, later a stringer is installed. anchor stem is injected in the ground by mortar which is pressed by high pressure through a distracted protective tube. in 12 hours a following anchor injection is made. after 7 days, the anchor is tested and compressed. anchors supporting retaining constructions are installed in the same level, usually above water level. if a designer has foreseen to transfer the pressure of retaining walls to other constructions, it means that permanent anchors are not to be installed as the pressure will be transferred to entablatures after their installation. in such a case, temporary ground anchors are installed which are cut off after the entablatures are installed. such a decision allows to save costs on retaining wall installation (fig. 1) geo 5 software was used for the tests. geo 5 is an effective software package based on analytical and finite element methods and developed for solving geotechnical problems. the obtained results were used in further tests. fig.1. view of principal computation scheme of a retaining wall with temporary ground anchors fig.1 illustrates principal computation scheme of a retaining wall with temporary ground anchors. ground layers are marked by numbers according to the geological excavation report (tables 1, 2). the depth scale is given on the right. the load used in the computation (10 kn/m2) is presented as distributed load on the top of the scheme. the load of the adjacent building (selected as 200 kn/m2) borne by the retaining wall is added at the bottom of the foundation. the blue dotted line shows the angle of internal friction, ° 25.00 41.00 44.00 43.00 42.00 cohesion of soil, kpa 0.00 0.00 0.00 0.00 0.00 angle of friction struc.-soil, °and compressed. 16.00 17.00 17.00 17.00 17.00 soil cohesionless cohesionless cohesionless cohesionless cohesionless poisson's ratio 0.35 0.35 0.35 0.35 0.35 deformation modulus, mpa 3.50 53.30 79.00 85.60 80.60 saturated unit weight, kn/m3 20.00 21.00 21.00 19.00 19.00 pattern marking in computation scheme 1 2 3 (5) 4 (7) 6 (8) (9) investigation conditions: retaining wall with temporary ground anchors driven to 6-meter depth from the top, the load received from the existing building is 200 kn/m2, the foundation of the existing building is 1 meter wide, the distance between the central axis of the foundation and the retaining wall is 1.5 m. wall footing was chosen as a foundation type for the research. temporary ground anchors are necessary to take over a huge tensile strength to supporting base layers for a limited period of time (< 2 years). a temporary ground anchor consists of an injected stem, a stringer with a free part and an anchor. external boring diameter of temporary ground anchors is 133 mm. anchors are bored by a spiral drill in protective tubes with air blow. when a hole is made cement mortar is poured, later a stringer is installed. anchor stem is injected in the ground by mortar which is pressed by high pressure through a distracted protective tube. in 12 hours a following anchor injection is made. after 7 days, the anchor is tested and compressed. anchors supporting retaining constructions are installed in the same level, usually above water level. if a designer has foreseen to transfer the pressure of retaining walls to other constructions, it means that permanent anchors are not to be installed as the pressure will be transferred to entablatures after their installation. in such a case, temporary ground anchors are installed which are cut off after the entablatures are installed. such a decision allows to save costs on retaining wall installation (fig. 1) geo 5 software was used for the tests. geo 5 is an effective software package based on analytical and finite element methods and developed for solving geotechnical problems. the obtained results were used in further tests. fig.1. view of principal computation scheme of a retaining wall with temporary ground anchors fig.1 illustrates principal computation scheme of a retaining wall with temporary ground anchors. ground layers are marked by numbers according to the geological excavation report (tables 1, 2). the depth scale is given on the right. the load used in the computation (10 kn/m2) is presented as distributed load on the top of the scheme. the load of the adjacent building (selected as 200 kn/m2) borne by the retaining wall is added at the bottom of the foundation. the blue dotted line shows the angle of internal friction, ° 25.00 41.00 44.00 43.00 42.00 cohesion of soil, kpa 0.00 0.00 0.00 0.00 0.00 angle of friction struc.-soil, °and compressed. 16.00 17.00 17.00 17.00 17.00 soil cohesionless cohesionless cohesionless cohesionless cohesionless poisson's ratio 0.35 0.35 0.35 0.35 0.35 deformation modulus, mpa 3.50 53.30 79.00 85.60 80.60 saturated unit weight, kn/m3 20.00 21.00 21.00 19.00 19.00 pattern marking in computation scheme 1 2 3 (5) 4 (7) 6 (8) (9) investigation conditions: retaining wall with temporary ground anchors driven to 6-meter depth from the top, the load received from the existing building is 200 kn/m2, the foundation of the existing building is 1 meter wide, the distance between the central axis of the foundation and the retaining wall is 1.5 m. wall footing was chosen as a foundation type for the research. temporary ground anchors are necessary to take over a huge tensile strength to supporting base layers for a limited period of time (< 2 years). a temporary ground anchor consists of an injected stem, a stringer with a free part and an anchor. external boring diameter of temporary ground anchors is 133 mm. anchors are bored by a spiral drill in protective tubes with air blow. when a hole is made cement mortar is poured, later a stringer is installed. anchor stem is injected in the ground by mortar which is pressed by high pressure through a distracted protective tube. in 12 hours a following anchor injection is made. after 7 days, the anchor is tested and compressed. anchors supporting retaining constructions are installed in the same level, usually above water level. if a designer has foreseen to transfer the pressure of retaining walls to other constructions, it means that permanent anchors are not to be installed as the pressure will be transferred to entablatures after their installation. in such a case, temporary ground anchors are installed which are cut off after the entablatures are installed. such a decision allows to save costs on retaining wall installation (fig. 1) geo 5 software was used for the tests. geo 5 is an effective software package based on analytical and finite element methods and developed for solving geotechnical problems. the obtained results were used in further tests. fig.1. view of principal computation scheme of a retaining wall with temporary ground anchors fig.1 illustrates principal computation scheme of a retaining wall with temporary ground anchors. ground layers are marked by numbers according to the geological excavation report (tables 1, 2). the depth scale is given on the right. the load used in the computation (10 kn/m2) is presented as distributed load on the top of the scheme. the load of the adjacent building (selected as 200 kn/m2) borne by the retaining wall is added at the bottom of the foundation. the blue dotted line shows the angle of internal friction, ° 25.00 41.00 44.00 43.00 42.00 cohesion of soil, kpa 0.00 0.00 0.00 0.00 0.00 angle of friction struc.-soil, °and compressed. 16.00 17.00 17.00 17.00 17.00 soil cohesionless cohesionless cohesionless cohesionless cohesionless poisson's ratio 0.35 0.35 0.35 0.35 0.35 deformation modulus, mpa 3.50 53.30 79.00 85.60 80.60 saturated unit weight, kn/m3 20.00 21.00 21.00 19.00 19.00 pattern marking in computation scheme 1 2 3 (5) 4 (7) 6 (8) (9) investigation conditions: retaining wall with temporary ground anchors driven to 6-meter depth from the top, the load received from the existing building is 200 kn/m2, the foundation of the existing building is 1 meter wide, the distance between the central axis of the foundation and the retaining wall is 1.5 m. wall footing was chosen as a foundation type for the research. temporary ground anchors are necessary to take over a huge tensile strength to supporting base layers for a limited period of time (< 2 years). a temporary ground anchor consists of an injected stem, a stringer with a free part and an anchor. external boring diameter of temporary ground anchors is 133 mm. anchors are bored by a spiral drill in protective tubes with air blow. when a hole is made cement mortar is poured, later a stringer is installed. anchor stem is injected in the ground by mortar which is pressed by high pressure through a distracted protective tube. in 12 hours a following anchor injection is made. after 7 days, the anchor is tested and compressed. anchors supporting retaining constructions are installed in the same level, usually above water level. if a designer has foreseen to transfer the pressure of retaining walls to other constructions, it means that permanent anchors are not to be installed as the pressure will be transferred to entablatures after their installation. in such a case, temporary ground anchors are installed which are cut off after the entablatures are installed. such a decision allows to save costs on retaining wall installation (fig. 1) geo 5 software was used for the tests. geo 5 is an effective software package based on analytical and finite element methods and developed for solving geotechnical problems. the obtained results were used in further tests. fig.1. view of principal computation scheme of a retaining wall with temporary ground anchors fig.1 illustrates principal computation scheme of a retaining wall with temporary ground anchors. ground layers are marked by numbers according to the geological excavation report (tables 1, 2). the depth scale is given on the right. the load used in the computation (10 kn/m2) is presented as distributed load on the top of the scheme. the load of the adjacent building (selected as 200 kn/m2) borne by the retaining wall is added at the bottom of the foundation. the blue dotted line shows the angle of internal friction, ° 25.00 41.00 44.00 43.00 42.00 cohesion of soil, kpa 0.00 0.00 0.00 0.00 0.00 angle of friction struc.-soil, °and compressed. 16.00 17.00 17.00 17.00 17.00 soil cohesionless cohesionless cohesionless cohesionless cohesionless poisson's ratio 0.35 0.35 0.35 0.35 0.35 deformation modulus, mpa 3.50 53.30 79.00 85.60 80.60 saturated unit weight, kn/m3 20.00 21.00 21.00 19.00 19.00 pattern marking in computation scheme 1 2 3 (5) 4 (7) 6 (8) (9) investigation conditions: retaining wall with temporary ground anchors driven to 6-meter depth from the top, the load received from the existing building is 200 kn/m2, the foundation of the existing building is 1 meter wide, the distance between the central axis of the foundation and the retaining wall is 1.5 m. wall footing was chosen as a foundation type for the research. temporary ground anchors are necessary to take over a huge tensile strength to supporting base layers for a limited period of time (< 2 years). a temporary ground anchor consists of an injected stem, a stringer with a free part and an anchor. external boring diameter of temporary ground anchors is 133 mm. anchors are bored by a spiral drill in protective tubes with air blow. when a hole is made cement mortar is poured, later a stringer is installed. anchor stem is injected in the ground by mortar which is pressed by high pressure through a distracted protective tube. in 12 hours a following anchor injection is made. after 7 days, the anchor is tested and compressed. anchors supporting retaining constructions are installed in the same level, usually above water level. if a designer has foreseen to transfer the pressure of retaining walls to other constructions, it means that permanent anchors are not to be installed as the pressure will be transferred to entablatures after their installation. in such a case, temporary ground anchors are installed which are cut off after the entablatures are installed. such a decision allows to save costs on retaining wall installation (fig. 1) geo 5 software was used for the tests. geo 5 is an effective software package based on analytical and finite element methods and developed for solving geotechnical problems. the obtained results were used in further tests. fig.1. view of principal computation scheme of a retaining wall with temporary ground anchors fig.1 illustrates principal computation scheme of a retaining wall with temporary ground anchors. ground layers are marked by numbers according to the geological excavation report (tables 1, 2). the depth scale is given on the right. the load used in the computation (10 kn/m2) is presented as distributed load on the top of the scheme. the load of the adjacent building (selected as 200 kn/m2) borne by the retaining wall is added at the bottom of the foundation. the blue dotted line shows the marking in computation scheme 1 2 3 (5) 4 (7) 6 (8) (9) fig. 1 view of principal computation scheme of a retaining wall with temporary ground anchors angle of internal friction, ° 25.00 41.00 44.00 43.00 42.00 cohesion of soil, kpa 0.00 0.00 0.00 0.00 0.00 angle of friction struc.-soil, °and compressed. 16.00 17.00 17.00 17.00 17.00 soil cohesionless cohesionless cohesionless cohesionless cohesionless poisson's ratio 0.35 0.35 0.35 0.35 0.35 deformation modulus, mpa 3.50 53.30 79.00 85.60 80.60 saturated unit weight, kn/m3 20.00 21.00 21.00 19.00 19.00 pattern marking in computation scheme 1 2 3 (5) 4 (7) 6 (8) (9) investigation conditions: retaining wall with temporary ground anchors driven to 6-meter depth from the top, the load received from the existing building is 200 kn/m2, the foundation of the existing building is 1 meter wide, the distance between the central axis of the foundation and the retaining wall is 1.5 m. wall footing was chosen as a foundation type for the research. temporary ground anchors are necessary to take over a huge tensile strength to supporting base layers for a limited period of time (< 2 years). a temporary ground anchor consists of an injected stem, a stringer with a free part and an anchor. external boring diameter of temporary ground anchors is 133 mm. anchors are bored by a spiral drill in protective tubes with air blow. when a hole is made cement mortar is poured, later a stringer is installed. anchor stem is injected in the ground by mortar which is pressed by high pressure through a distracted protective tube. in 12 hours a following anchor injection is made. after 7 days, the anchor is tested and compressed. anchors supporting retaining constructions are installed in the same level, usually above water level. if a designer has foreseen to transfer the pressure of retaining walls to other constructions, it means that permanent anchors are not to be installed as the pressure will be transferred to entablatures after their installation. in such a case, temporary ground anchors are installed which are cut off after the entablatures are installed. such a decision allows to save costs on retaining wall installation (fig. 1) geo 5 software was used for the tests. geo 5 is an effective software package based on analytical and finite element methods and developed for solving geotechnical problems. the obtained results were used in further tests. fig.1. view of principal computation scheme of a retaining wall with temporary ground anchors fig.1 illustrates principal computation scheme of a retaining wall with temporary ground anchors. ground layers are marked by numbers according to the geological excavation report (tables 1, 2). the depth scale is given on the right. the load used in the computation (10 kn/m2) is presented as distributed load on the top of the scheme. the load of the adjacent building (selected as 200 kn/m2) borne by the retaining wall is added at the bottom of the foundation. the blue dotted line shows the retaining constructions are installed in the same level, usually above water level. if a designer has foreseen to transfer the pressure of retaining walls to other constructions, it means that permanent anchors are not to be installed as the pressure will be transferred to entablatures after their installation. in such a case, temporary ground anchors are installed which are cut off after the entablatures are installed. such a decision allows to save costs on retaining wall installation (fig. 1) geo 5 software was used for the tests. geo 5 is an effective software package based on analytical and finite element methods and developed for solving geotechnical problems. the obtained results were used in further tests. 57 journal of sustainable architecture and civil engineering 2020/1/26 fig.1 illustrates principal computation scheme of a retaining wall with temporary ground anchors. ground layers are marked by numbers according to the geological excavation report (tables 1, 2). the depth scale is given on the right. the load used in the computation (10 kn/m2) is presented as distributed load on the top of the scheme. the load of the adjacent building (selected as 200 kn/m2) borne by the retaining wall is added at the bottom of the foundation. the blue dotted line shows the ground water level, which is different on both sides of the structure. it is the maximum level planned for the service life of the structure. the length and height of the structure shows the maximum excavation depth. the triangle marking in the scheme shows the depth of the ground anchor (fig. 3). a survey was conducted according to the developed questionnaire based on specific conditions and criteria used by the interviewees to evaluate each type of the retaining wall in points from 1 to 5. the questionnaire was given to the staff of the companies constructing retaining walls with ground anchors in lithuania: uab projektana, uab vilniaus rentinys, uab geotechnikos grupė ii and uab pamatų ranga. the following retaining wall construction principles were evaluated by the questionnaire (table 3). table 3 initial information for interviewees case 1 retaining walls with ground anchors in sandy soil with a high level of groundwater berlin wall steel grade s355 heb 280 type profiles, length l=12 m pile wall piles with the diameter of ø450 mm, length l=11 m, reinforced with 8ø18 mm s500 tendons along the entire length, concrete class c25/30 sheet piles steel grade s355 larsen vl503 tongue, l=10 m case 2 retaining walls with ground anchors installed close to existing buildings in sandy soil with a high level of groundwater berlin wall steel grades355 heb 340 type profiles, length l=12 m pile wall piles with the diameter of ø450 mm, length l=12 m, reinforced with 8ø20 mm s500 tendons along the entire length, concrete class c25/30 sheet piles steel grade s355 larsen vl606 tongue, l=12 m case 3 retaining walls with ground anchors in sandy soil (without groundwater and a building in close proximity) berlin wall steel grade s355 heb 240 type profiles, length l=10 m pile wall piles with the diameter of ø450 mm, length l=9 m, reinforced with 8ø18 mm s500 tendons along the entire length, concrete class c25/30 sheet piles steel grade s355 larsen vl503 tongue, l=8 m case 4 retaining walls with ground anchors in sandy soil (without water) close to existing buildings) berlin wall steel grade s355 heb 260 type profiles, length l=10 m pile wall piles with the diameter of ø450 mm, length l=11 m, reinforced with 8ø25 mm s500 tendons along the entire length, concrete class c25/30 sheet piles steel grade s355 larsen vl503 tongue, l=9 m case 5 retaining walls with ground anchors in clay soil berlin wall steel grade s355 heb 220 type profiles, length l=8 m pile wall piles with the diameter of ø450 mm, length l=8 m, reinforced with 8ø16 mm s500 tendons along the entire length, concrete class c25/30 sheet piles steel grade s355 larsen vl503 tongue, l=8 m case 6 retaining walls with ground anchors in clay soil close to existing building berlin wall steel grade s355 heb 300 type profiles, length l=9 m pile wall piles with the diameter of ø450 mm, length l=9 m, reinforced with 8ø18 mm s500 tendons along the entire length, concrete class c25/30 sheet piles steel grade s355 larsen vl503 tongue, l=9 m journal of sustainable architecture and civil engineering 2020/1/26 58 each case was analysed with the selected types of retaining walls (options).the views of the selected types of retaining walls are given in figs 2 a-c. fig. 2 the views of the selected types of retaining walls (www.aarsleff.com. pl/lt) a) a1 berlin wall b) a2 pile wall c) a3 – sheet wall a) a1 berlin wall b) a2 pile wall c) a3 – sheet wall fig.2. the views of the selected types of retaining walls (www.aarsleff.com.pl/lt) the same types of wall installation and retaining wall options and criteria applied for their evaluation were also used with other evaluation techniques. the options of supporting walls were evaluated in the questionnaire according to the following criteria:  k1 – labour cost, eur/m, which means the cost of labour to install 1 meter of retaining wall.  k2 –machinery cost, eur/m, which means the cost of machinery to install 1 meter of retaining wall.  k3 –material cost, eur/m, which means the cost of materials to install 1 meter of retaining wall.  k4 – seasonality, scores, which means the influence of the season (spring, summer, autumn, winter), for the selection of retaining wall option.  k5 – installation time, scores, which means the time required to install the selected type of retaining wall. evaluation criteria: the values of labour cost, eur/m; machinery cost, eur/m; cost of materials, eur/m calculated using estimate computation programme. seasonality in scores was evaluated considering the possibility to install the wall in all seasons and the installation time in scores was calculated considering the complexity of work. the entropy technique was used to determine the weighting factor of evaluation theoretical and integrated criteria’s. the selected values of criteria (k1-k5) that describe the options of selected types of retaining walls are presented in the initial matrix a of alternative solutions (table 4). table 4. view of initial matrix a of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … … total sum … … … … … optimization direction min min min max max a) a1 berlin wall b) a2 pile wall c) a3 – sheet wall fig.2. the views of the selected types of retaining walls (www.aarsleff.com.pl/lt) the same types of wall installation and retaining wall options and criteria applied for their evaluation were also used with other evaluation techniques. the options of supporting walls were evaluated in the questionnaire according to the following criteria:  k1 – labour cost, eur/m, which means the cost of labour to install 1 meter of retaining wall.  k2 –machinery cost, eur/m, which means the cost of machinery to install 1 meter of retaining wall.  k3 –material cost, eur/m, which means the cost of materials to install 1 meter of retaining wall.  k4 – seasonality, scores, which means the influence of the season (spring, summer, autumn, winter), for the selection of retaining wall option.  k5 – installation time, scores, which means the time required to install the selected type of retaining wall. evaluation criteria: the values of labour cost, eur/m; machinery cost, eur/m; cost of materials, eur/m calculated using estimate computation programme. seasonality in scores was evaluated considering the possibility to install the wall in all seasons and the installation time in scores was calculated considering the complexity of work. the entropy technique was used to determine the weighting factor of evaluation theoretical and integrated criteria’s. the selected values of criteria (k1-k5) that describe the options of selected types of retaining walls are presented in the initial matrix a of alternative solutions (table 4). table 4. view of initial matrix a of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … … total sum … … … … … optimization direction min min min max max a) a1 berlin wall b) a2 pile wall c) a3 – sheet wall fig.2. the views of the selected types of retaining walls (www.aarsleff.com.pl/lt) the same types of wall installation and retaining wall options and criteria applied for their evaluation were also used with other evaluation techniques. the options of supporting walls were evaluated in the questionnaire according to the following criteria:  k1 – labour cost, eur/m, which means the cost of labour to install 1 meter of retaining wall.  k2 –machinery cost, eur/m, which means the cost of machinery to install 1 meter of retaining wall.  k3 –material cost, eur/m, which means the cost of materials to install 1 meter of retaining wall.  k4 – seasonality, scores, which means the influence of the season (spring, summer, autumn, winter), for the selection of retaining wall option.  k5 – installation time, scores, which means the time required to install the selected type of retaining wall. evaluation criteria: the values of labour cost, eur/m; machinery cost, eur/m; cost of materials, eur/m calculated using estimate computation programme. seasonality in scores was evaluated considering the possibility to install the wall in all seasons and the installation time in scores was calculated considering the complexity of work. the entropy technique was used to determine the weighting factor of evaluation theoretical and integrated criteria’s. the selected values of criteria (k1-k5) that describe the options of selected types of retaining walls are presented in the initial matrix a of alternative solutions (table 4). table 4. view of initial matrix a of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … … total sum … … … … … optimization direction min min min max max the same types of wall installation and retaining wall options and criteria applied for their evaluation were also used with other evaluation techniques. the options of supporting walls were evaluated in the questionnaire according to the following criteria: _ k1 – labour cost, eur/m, which means the cost of labour to install 1 meter of retaining wall. _ k2 –machinery cost, eur/m, which means the cost of machinery to install 1 meter of retaining wall. _ k3 –material cost, eur/m, which means the cost of materials to install 1 meter of retaining wall. _ k4 – seasonality, scores, which means the influence of the season (spring, summer, autumn, winter), for the selection of retaining wall option. _ k5 – installation time, scores, which means the time required to install the selected type of retaining wall. evaluation criteria: the values of labour cost, eur/m; machinery cost, eur/m; cost of materials, eur/m calculated using estimate computation programme. seasonality in scores was evaluated considering the possibility to install the wall in all seasons and the installation time in scores was calculated considering the complexity of work. the entropy technique was used to determine the weighting factor of evaluation theoretical and integrated criteria’s. the selected values of criteria (k1-k5) that describe the options of selected types of retaining walls are presented in the initial matrix a of alternative solutions (table 4). table 4 view of initial matrix a of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … … total sum … … … … … optimization direction min min min max max 59 journal of sustainable architecture and civil engineering 2020/1/26 the initial matrix a was normalised using equation (1): the initial matrix a was normalised using equation (1):  njmikaiv x x p ijm i ij ij ij ,1;,1,; 1    (1) normalization of initial matrix a produces non-dimensional values (xi, j). entropy order ej is determined for each criterion according to equation (2):     m knjmippke m i ijijj ln 1 ,,1,,1,ln 1    (2) additional matrix  ijij pp ln is created to make the calculation easier. the criteria change level dj is determined according to equation (3):  njkured jj ,1,1  (3) as all criteria are equally significant, theoretical weight of criteria is found using (4) equation:    nj d d q n j j j tj ,1; 1    (4) the integrated weight of criteria is calculated using (5) equation:   ),1(; 1 )( )( 0 nj qq qq q n j tjj tjj j       (5) the criteria weighting factor results are presented in table. a multiple criteria decision analysis method was also applied to select the most rational option for the erection of the retaining wall. to select the most rational option for the erection of the retaining wall was created the initial matrix b, which is presented in table 5. table 5. view of initial matrix b of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … …   m i ijx 1 2 … … … … … optimization direction min min min max max integrated significance, % … … … … … theoretical significance, % … … … … … (1) normalization of initial matrix a produces non-dimensional values (xi, j). entropy order ej is determined for each criterion according to equation (2): the initial matrix a was normalised using equation (1):  njmikaiv x x p ijm i ij ij ij ,1;,1,; 1    (1) normalization of initial matrix a produces non-dimensional values (xi, j). entropy order ej is determined for each criterion according to equation (2):     m knjmippke m i ijijj ln 1 ,,1,,1,ln 1    (2) additional matrix  ijij pp ln is created to make the calculation easier. the criteria change level dj is determined according to equation (3):  njkured jj ,1,1  (3) as all criteria are equally significant, theoretical weight of criteria is found using (4) equation:    nj d d q n j j j tj ,1; 1    (4) the integrated weight of criteria is calculated using (5) equation:   ),1(; 1 )( )( 0 nj qq qq q n j tjj tjj j       (5) the criteria weighting factor results are presented in table. a multiple criteria decision analysis method was also applied to select the most rational option for the erection of the retaining wall. to select the most rational option for the erection of the retaining wall was created the initial matrix b, which is presented in table 5. table 5. view of initial matrix b of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … …   m i ijx 1 2 … … … … … optimization direction min min min max max integrated significance, % … … … … … theoretical significance, % … … … … … (2) additional matrix (pij ∙ lnpij) is created to make the calculation easier. the criteria change level dj is determined according to equation (3): the initial matrix a was normalised using equation (1):  njmikaiv x x p ijm i ij ij ij ,1;,1,; 1    (1) normalization of initial matrix a produces non-dimensional values (xi, j). entropy order ej is determined for each criterion according to equation (2):     m knjmippke m i ijijj ln 1 ,,1,,1,ln 1    (2) additional matrix  ijij pp ln is created to make the calculation easier. the criteria change level dj is determined according to equation (3):  njkured jj ,1,1  (3) as all criteria are equally significant, theoretical weight of criteria is found using (4) equation:    nj d d q n j j j tj ,1; 1    (4) the integrated weight of criteria is calculated using (5) equation:   ),1(; 1 )( )( 0 nj qq qq q n j tjj tjj j       (5) the criteria weighting factor results are presented in table. a multiple criteria decision analysis method was also applied to select the most rational option for the erection of the retaining wall. to select the most rational option for the erection of the retaining wall was created the initial matrix b, which is presented in table 5. table 5. view of initial matrix b of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … …   m i ijx 1 2 … … … … … optimization direction min min min max max integrated significance, % … … … … … theoretical significance, % … … … … … (3) as all criteria are equally significant, theoretical weight of criteria is found using (4) equation: the initial matrix a was normalised using equation (1):  njmikaiv x x p ijm i ij ij ij ,1;,1,; 1    (1) normalization of initial matrix a produces non-dimensional values (xi, j). entropy order ej is determined for each criterion according to equation (2):     m knjmippke m i ijijj ln 1 ,,1,,1,ln 1    (2) additional matrix  ijij pp ln is created to make the calculation easier. the criteria change level dj is determined according to equation (3):  njkured jj ,1,1  (3) as all criteria are equally significant, theoretical weight of criteria is found using (4) equation:    nj d d q n j j j tj ,1; 1    (4) the integrated weight of criteria is calculated using (5) equation:   ),1(; 1 )( )( 0 nj qq qq q n j tjj tjj j       (5) the criteria weighting factor results are presented in table. a multiple criteria decision analysis method was also applied to select the most rational option for the erection of the retaining wall. to select the most rational option for the erection of the retaining wall was created the initial matrix b, which is presented in table 5. table 5. view of initial matrix b of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … …   m i ijx 1 2 … … … … … optimization direction min min min max max integrated significance, % … … … … … theoretical significance, % … … … … … (4) the integrated weight of criteria is calculated using (5) equation: the initial matrix a was normalised using equation (1):  njmikaiv x x p ijm i ij ij ij ,1;,1,; 1    (1) normalization of initial matrix a produces non-dimensional values (xi, j). entropy order ej is determined for each criterion according to equation (2):     m knjmippke m i ijijj ln 1 ,,1,,1,ln 1    (2) additional matrix  ijij pp ln is created to make the calculation easier. the criteria change level dj is determined according to equation (3):  njkured jj ,1,1  (3) as all criteria are equally significant, theoretical weight of criteria is found using (4) equation:    nj d d q n j j j tj ,1; 1    (4) the integrated weight of criteria is calculated using (5) equation:   ),1(; 1 )( )( 0 nj qq qq q n j tjj tjj j       (5) the criteria weighting factor results are presented in table. a multiple criteria decision analysis method was also applied to select the most rational option for the erection of the retaining wall. to select the most rational option for the erection of the retaining wall was created the initial matrix b, which is presented in table 5. table 5. view of initial matrix b of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … …   m i ijx 1 2 … … … … … optimization direction min min min max max integrated significance, % … … … … … theoretical significance, % … … … … … (5) the criteria weighting factor results are presented in table. a multiple criteria decision analysis method was also applied to select the most rational option for the erection of the retaining wall. to select the most rational option for the erection of the retaining wall was created the initial matrix b, which is presented in table 5. criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … … the initial matrix a was normalised using equation (1):  njmikaiv x x p ijm i ij ij ij ,1;,1,; 1    (1) normalization of initial matrix a produces non-dimensional values (xi, j). entropy order ej is determined for each criterion according to equation (2):     m knjmippke m i ijijj ln 1 ,,1,,1,ln 1    (2) additional matrix  ijij pp ln is created to make the calculation easier. the criteria change level dj is determined according to equation (3):  njkured jj ,1,1  (3) as all criteria are equally significant, theoretical weight of criteria is found using (4) equation:    nj d d q n j j j tj ,1; 1    (4) the integrated weight of criteria is calculated using (5) equation:   ),1(; 1 )( )( 0 nj qq qq q n j tjj tjj j       (5) the criteria weighting factor results are presented in table. a multiple criteria decision analysis method was also applied to select the most rational option for the erection of the retaining wall. to select the most rational option for the erection of the retaining wall was created the initial matrix b, which is presented in table 5. table 5. view of initial matrix b of alternative solutions criteria options k1, labour cost, eur/m k2, machinery cost, eur/m k3, material cost, eur/m k4, seasonality, scores k5, installation time, scores a1 … … … … … a2 … … … … … a3 … … … … …   m i ijx 1 2 … … … … … optimization direction min min min max max integrated significance, % … … … … … theoretical significance, % … … … … … … … … … … optimization direction min min min max max integrated significance, % … … … … … theoretical significance, % … … … … … table 5 view of initial matrix b of alternative solutions journal of sustainable architecture and civil engineering 2020/1/26 60 afterwards, matrix b was normalized. the reason for matrix normalization is that the data in initial matrix b are expressed in different units of measurement and thus are not possible to compare. normalization of initial matrix b produces non-dimensional values. matrix b was normalized using (6) equation: afterwards, matrix b was normalized. the reason for matrix normalization is that the data in initial matrix b are expressed in different units of measurement and thus are not possible to compare. normalization of initial matrix b produces non-dimensional values. matrix b was normalized using (6) equation:    j i ij ij ij x x x 1 2 , i 1, m ; j  1,n; (6) here: xij – i – line and j – column of matrix. following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (7) equation: b* = [b] · [q], (7) the ideal best condition a+ (the best value) and the ideal worst condition a(the worst value) are found. distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed using (8,9) equations:      j n j iji ffl 1 , i 1,m ; j  1,n; (8)      j n j iji ffl 1 , i 1,m ; j  1,n; (9) the relative proximity of compared options to the ideal option is found, i.e. criterion kbit is calculated. having the criterion kbitvalue calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion kbit. in the last stage the degree of utilityni of compared options is calculated using (10) equation:     ii i bit ll l k , i 1,m ; j 1,n; (10) the most rational engineering option is the one with the highest value. then the degree of utilityis calculated according to equation 11 to compare the value of the analysed option with the value of the ideal option. (11) the rational engineering options are presented in table. results rational types of permanent retaining walls with ground anchors were calculatedusing the software geo 5, taking into consideration different grounds and adjacent buildings. the summary of results leads to the conclusion that in terms of work complexity and costs, it is rational to install retaining walls in clay grounds. in clay grounds lower movement of structures occurs and there is no need to lower the ground water level. smaller cross-section of the tendons is required to retain the ground load compared to sand grounds. the consumption of cement and water mortar is much higher in sandy grounds compared to the clay grounds. (6) here: xij – i – line and j – column of matrix. following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (7) equation: afterwards, matrix b was normalized. the reason for matrix normalization is that the data in initial matrix b are expressed in different units of measurement and thus are not possible to compare. normalization of initial matrix b produces non-dimensional values. matrix b was normalized using (6) equation:    j i ij ij ij x x x 1 2 , i 1,m ; j  1,n; (6) here: xij – i – line and j – column of matrix. following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (7) equation: b* = [b] · [q], (7) the ideal best condition a+ (the best value) and the ideal worst condition a(the worst value) are found. distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed using (8,9) equations:      j n j iji ffl 1 , i 1,m ; j  1,n; (8)      j n j iji ffl 1 , i 1,m ; j  1,n; (9) the relative proximity of compared options to the ideal option is found, i.e. criterion kbit is calculated. having the criterion kbitvalue calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion kbit. in the last stage the degree of utilityni of compared options is calculated using (10) equation:     ii i bit ll l k , i 1,m ; j 1,n; (10) the most rational engineering option is the one with the highest value. then the degree of utilityis calculated according to equation 11 to compare the value of the analysed option with the value of the ideal option. (11) the rational engineering options are presented in table. results rational types of permanent retaining walls with ground anchors were calculatedusing the software geo 5, taking into consideration different grounds and adjacent buildings. the summary of results leads to the conclusion that in terms of work complexity and costs, it is rational to install retaining walls in clay grounds. in clay grounds lower movement of structures occurs and there is no need to lower the ground water level. smaller cross-section of the tendons is required to retain the ground load compared to sand grounds. the consumption of cement and water mortar is much higher in sandy grounds compared to the clay grounds. (7) the ideal best condition a+ (the best value) and the ideal worst condition a(the worst value) are found. distances between the real option ai and the ideal best condition a +, as well as between the real option ai and the ideal worst condition a are computed using (8,9) equations: afterwards, matrix b was normalized. the reason for matrix normalization is that the data in initial matrix b are expressed in different units of measurement and thus are not possible to compare. normalization of initial matrix b produces non-dimensional values. matrix b was normalized using (6) equation:    j i ij ij ij x x x 1 2 , i 1,m ; j  1,n; (6) here: xij – i – line and j – column of matrix. following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (7) equation: b* = [b] · [q], (7) the ideal best condition a+ (the best value) and the ideal worst condition a(the worst value) are found. distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed using (8,9) equations:      j n j iji ffl 1 , i 1, m ; j 1,n (8)      j n j iji ffl 1 , i 1,m ; j  1,n; (9) the relative proximity of compared options to the ideal option is found, i.e. criterion kbit is calculated. having the criterion kbitvalue calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion kbit. in the last stage the degree of utilityni of compared options is calculated using (10) equation:     ii i bit ll l k , i 1,m ; j 1,n; (10) the most rational engineering option is the one with the highest value. then the degree of utilityis calculated according to equation 11 to compare the value of the analysed option with the value of the ideal option. (11) the rational engineering options are presented in table. results rational types of permanent retaining walls with ground anchors were calculatedusing the software geo 5, taking into consideration different grounds and adjacent buildings. the summary of results leads to the conclusion that in terms of work complexity and costs, it is rational to install retaining walls in clay grounds. in clay grounds lower movement of structures occurs and there is no need to lower the ground water level. smaller cross-section of the tendons is required to retain the ground load compared to sand grounds. the consumption of cement and water mortar is much higher in sandy grounds compared to the clay grounds. ;  (8) afterwards, matrix b was normalized. the reason for matrix normalization is that the data in initial matrix b are expressed in different units of measurement and thus are not possible to compare. normalization of initial matrix b produces non-dimensional values. matrix b was normalized using (6) equation:    j i ij ij ij x x x 1 2 , i 1,m ; j  1,n; (6) here: xij – i – line and j – column of matrix. following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (7) equation: b* = [b] · [q], (7) the ideal best condition a+ (the best value) and the ideal worst condition a(the worst value) are found. distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed using (8,9) equations:      j n j iji ffl 1 , i 1,m ; j  1,n; (8)      j n j iji ffl 1 , i 1, m ; j  1,n (9) the relative proximity of compared options to the ideal option is found, i.e. criterion kbit is calculated. having the criterion kbitvalue calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion kbit. in the last stage the degree of utilityni of compared options is calculated using (10) equation:     ii i bit ll l k , i 1,m ; j 1,n; (10) the most rational engineering option is the one with the highest value. then the degree of utilityis calculated according to equation 11 to compare the value of the analysed option with the value of the ideal option. (11) the rational engineering options are presented in table. results rational types of permanent retaining walls with ground anchors were calculatedusing the software geo 5, taking into consideration different grounds and adjacent buildings. the summary of results leads to the conclusion that in terms of work complexity and costs, it is rational to install retaining walls in clay grounds. in clay grounds lower movement of structures occurs and there is no need to lower the ground water level. smaller cross-section of the tendons is required to retain the ground load compared to sand grounds. the consumption of cement and water mortar is much higher in sandy grounds compared to the clay grounds. ; (9) the relative proximity of compared options to the ideal option is found, i.e. criterion kbit is calculated. having the criterion kbitvalue calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion kbit. in the last stage the degree of utilityni of compared options is calculated using (10) equation: afterwards, matrix b was normalized. the reason for matrix normalization is that the data in initial matrix b are expressed in different units of measurement and thus are not possible to compare. normalization of initial matrix b produces non-dimensional values. matrix b was normalized using (6) equation:    j i ij ij ij x x x 1 2 , i 1,m ; j  1,n; (6) here: xij – i – line and j – column of matrix. following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (7) equation: b* = [b] · [q], (7) the ideal best condition a+ (the best value) and the ideal worst condition a(the worst value) are found. distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed using (8,9) equations:      j n j iji ffl 1 , i 1,m ; j  1,n; (8)      j n j iji ffl 1 , i 1,m ; j  1,n; (9) the relative proximity of compared options to the ideal option is found, i.e. criterion kbit is calculated. having the criterion kbitvalue calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion kbit. in the last stage the degree of utilityni of compared options is calculated using (10) equation:     ii i bit ll l k , i 1, m ; j 1, n (10) the most rational engineering option is the one with the highest value. then the degree of utilityis calculated according to equation 11 to compare the value of the analysed option with the value of the ideal option. (11) the rational engineering options are presented in table. results rational types of permanent retaining walls with ground anchors were calculatedusing the software geo 5, taking into consideration different grounds and adjacent buildings. the summary of results leads to the conclusion that in terms of work complexity and costs, it is rational to install retaining walls in clay grounds. in clay grounds lower movement of structures occurs and there is no need to lower the ground water level. smaller cross-section of the tendons is required to retain the ground load compared to sand grounds. the consumption of cement and water mortar is much higher in sandy grounds compared to the clay grounds.   ; (10) the most rational engineering option is the one with the highest value. then the degree of utilityis calculated according to equation 11 to compare the value of the analysed option with the value of the ideal option. afterwards, matrix b was normalized. the reason for matrix normalization is that the data in initial matrix b are expressed in different units of measurement and thus are not possible to compare. normalization of initial matrix b produces non-dimensional values. matrix b was normalized using (6) equation:    j i ij ij ij x x x 1 2 , i 1,m ; j  1,n; (6) here: xij – i – line and j – column of matrix. following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (7) equation: b* = [b] · [q], (7) the ideal best condition a+ (the best value) and the ideal worst condition a(the worst value) are found. distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed using (8,9) equations:      j n j iji ffl 1 , i 1,m ; j  1,n; (8)      j n j iji ffl 1 , i 1,m ; j  1,n; (9) the relative proximity of compared options to the ideal option is found, i.e. criterion kbit is calculated. having the criterion kbitvalue calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion kbit. in the last stage the degree of utilityni of compared options is calculated using (10) equation:     ii i bit ll l k , i 1,m ; j 1,n; (10) the most rational engineering option is the one with the highest value. then the degree of utilityis calculated according to equation 11 to compare the value of the analysed option with the value of the ideal option. (11) the rational engineering options are presented in table. results rational types of permanent retaining walls with ground anchors were calculatedusing the software geo 5, taking into consideration different grounds and adjacent buildings. the summary of results leads to the conclusion that in terms of work complexity and costs, it is rational to install retaining walls in clay grounds. in clay grounds lower movement of structures occurs and there is no need to lower the ground water level. smaller cross-section of the tendons is required to retain the ground load compared to sand grounds. the consumption of cement and water mortar is much higher in sandy grounds compared to the clay grounds. (11) the rational engineering options are presented in table. rational types of permanent retaining walls with ground anchors were calculatedusing the software geo 5, taking into consideration different grounds and adjacent buildings. the summary of results leads to the conclusion that in terms of work complexity and costs, it is rational to install retaining walls in clay grounds. in clay grounds lower movement of structures occurs and there is no need to lower the ground water level. smaller cross-section of the tendons is required to retain the ground load compared to sand grounds. the consumption of cement and water mortar is much higher in sandy grounds compared to the clay grounds. results 61 journal of sustainable architecture and civil engineering 2020/1/26 it can be assumed from the summary of survey results, which show the rational type of retaining wall with ground anchors selected by the evaluators according to the given conditions and evaluation criteria, that a pile wall is the rational solution for retaining walls with ground anchors erected next to existing buildings, whereas in all other cases the steel sheet pile is the most rational option. adjacent buildings have a great influence on retaining wall installation, especially the buildings with shallow foundations, because the load borne by the foundation at the retaining wall is transferred to the structure. if the existing buildings have pile foundations, the load is usually transferred to deeper ground layers and has less influence on the retaining wall. all chosen cases from 1 to 6 were distinguished after criteria weights were determined using the entropy technique. for example, one case is an existing building close to the retaining wall. in this case the most significant theoretical criteria were seasonality and installation time, and the most significant integrated criterion was the installation time. the other one case is the retaining wall without an existing building in the vicinity. in this case the most significant criterion, both theoretical and integrated, is the cost of machinery. the criteria weighting factor results are presented in table 6. table 6 criteria priorities for each alternative solution using entropy technique evaluation of criteria weight k1, labour cost k2, machinery cost k3, material cost k4, seasonality k5, installation time case 1 retaining walls with ground anchors in sandy soil with a high level of ground water theoretical 0.1482 0.5612 0.0374 0.1991 0.0541 integrated 0.2281 0.5759 0.0384 0.1021 0.0556 case 2 ret. walls with ground anchors installed close to existing buildings in sandy soil with a high level of ground water theoretical 0.0672 0.2444 0.1069 0.2908 0.2908 integrated 0.1135 0.2752 0.1204 .01637 0.3273 case 3 retaining walls with ground anchors in sandy soil (without ground water and a building in close proximity) theoretical 0.1914 0.7150 0.0196 0.0147 0.0593 integrated 0.2638 0.6570 0.0180 0.0068 0.0544 case 4 retaining walls with ground anchors in sandy soil (without water) close to existing buildings) theoretical 0.0511 0.2272 0.0210 0.3503 0.3503 integrated 0.0902 0.2671 0.0247 0.2060 0.4120 case 5 retaining walls with ground anchors in clay soil theoretical 0.1614 0.6028 0.1359 0.0500 0.0500 integrated 0.2293 0.5710 0.1287 0.0237 0.0473 case 6 retaining walls with ground anchors in clay soil close to existing building theoretical 0.0701 0.2617 0.0455 0.3114 0.3114 integrated 0.1195 0.2976 0.0518 0.1770 0.3541 a multiple criteria analysis of three options of retaining walls with ground anchors installed in sandy ground with high ground water level and an existing building in close proximity revealed that the best solution is option 2. this option is a pile wall. the maximum value of the degrees of utility (%) was obtained in this case. piles with the diameter of ø450 mm and length l=12 m, journal of sustainable architecture and civil engineering 2020/1/26 62 reinforced with 8ø20 mm tendons along the entire length should be used for the retaining wall. multiple criteria analysis of three options of retaining walls with ground anchors in clay ground shows that option 1 is the best design solution. it means that berlin wall is the best retaining wall type for clay ground. heb 220 type profiles with the length l=8 m should be used for the erection of the retaining wall. fig. 3 computation schemes of a retaining walls of the best rational solutions multiple criteria analysis of three options of retaining walls with ground anchors in clay ground shows that option 1 is the best design solution. it means that berlin wall is the best retaining wall type for clay ground. heb 220 type profiles with the length l=8 m should be used for the erection of the retaining wall. computation scheme of berlin wall (case 1) computation scheme of berlin wall (case 3) computation scheme of berlin wall (case 5) computation scheme of pile wall (case 2) computation scheme of pile wall (case 4) computation scheme of berlin wall (case 1) multiple criteria analysis of three options of retaining walls with ground anchors in clay ground shows that option 1 is the best design solution. it means that berlin wall is the best retaining wall type for clay ground. heb 220 type profiles with the length l=8 m should be used for the erection of the retaining wall. computation scheme of berlin wall (case 1) computation scheme of berlin wall (case 3) computation scheme of berlin wall (case 5) computation scheme of pile wall (case 2) computation scheme of pile wall (case 4) computation scheme of pile wall (case 2) multiple criteria analysis of three options of retaining walls with ground anchors in clay ground shows that option 1 is the best design solution. it means that berlin wall is the best retaining wall type for clay ground. heb 220 type profiles with the length l=8 m should be used for the erection of the retaining wall. computation scheme of berlin wall (case 1) computation scheme of berlin wall (case 3) computation scheme of berlin wall (case 5) computation scheme of pile wall (case 2) computation scheme of pile wall (case 4) computation scheme of berlin wall (case 3) multiple criteria analysis of three options of retaining walls with ground anchors in clay ground shows that option 1 is the best design solution. it means that berlin wall is the best retaining wall type for clay ground. heb 220 type profiles with the length l=8 m should be used for the erection of the retaining wall. computation scheme of berlin wall (case 1) computation scheme of berlin wall (case 3) computation scheme of berlin wall (case 5) computation scheme of pile wall (case 2) computation scheme of pile wall (case 4) computation scheme of pile wall (case 4) multiple criteria analysis of three options of retaining walls with ground anchors in clay ground shows that option 1 is the best design solution. it means that berlin wall is the best retaining wall type for clay ground. heb 220 type profiles with the length l=8 m should be used for the erection of the retaining wall. computation scheme of berlin wall (case 1) computation scheme of berlin wall (case 3) computation scheme of berlin wall (case 5) computation scheme of pile wall (case 2) computation scheme of pile wall (case 4) computation scheme of berlin wall (case 5) computation scheme of pile wall (case 6) fig.3. computation schemes of a retaining walls of the best rational solutions fig. 3 illustrates the best rational solutions of retaining wall computation schemes. in fig. 3 the computation scheme of sheet wall was not given because in all investigated cases (table 6) this type of retaining wall was not a rational solution. table 6. degree of utility for each alternative solution using entropy technique alternatives options a1 a2 a3 case 1 retaining walls with ground anchors in sandy ground with a high level of ground water degree of utility options, % 100.0 7.2 89.2 case 2 ret. walls with ground anchors installed close to existing buildings in sandy ground with a high level of ground water degree of utility options, % 72.1 100.0 46.2 case 3 retaining walls with ground anchors in sandy ground (without ground water and a building in close proximity) degree of utility options, % 100.0 0.4 78.1 case 4 retaining walls with ground anchors in sandy ground (without water) close to existing buildings) degree of utility options, % 48.9 100.0 34.1 case 5 retaining walls with ground anchors in clay ground degree of utility options, % 100.0 9.1 73.0 case 6 retaining walls with ground anchors in clay ground close to existing building degree of utility options, % 68.7 100.0 52.0 a multi-criteria evaluation by the method of efficiency value proved that berlin wall is the most rational version of a retaining wall if it is installed with ground anchors in sandy soil with a high level of groundwater or without it and in clayey soil with no building in the vicinity. while installing it, the cost of human labour is 2 times, and the cost of mechanism work is even five times lower than the installation of a pile wall. however, a pile wall is the most rational version of a retaining wall in sandy soil with a high level of groundwater or without it and in clayey soil with a building nearby. installation of a pile retaining wall needs 1.5 times less materials than a berlin wall and it is the most cost-effective option from the point of view of duration. computation scheme of pile wall (case 6) 63 journal of sustainable architecture and civil engineering 2020/1/26 a multi-criteria evaluation by the method of efficiency value proved that berlin wall is the most rational version of a retaining wall if it is installed with ground anchors in sandy soil with a high level of groundwater or without it and in clayey soil with no building in the vicinity. while installing it, the cost of human labour is 2 times, and the cost of mechanism work is even five times lower than the installation of a pile wall. however, a pile wall is the most rational version of a retaining wall in sandy soil with a high level of groundwater or without it and in clayey soil with a building nearby. installation of a pile retaining wall needs 1.5 times less materials than a berlin wall and it is the most cost-effective option from the point of view of duration. 1. in accordance with the provided conditions and criteria in the questionnaire, the results of the questionnaire from the enterprises experienced in installing retaining walls with ground anchors indicate that a pile wall is appropriate to install next to existing buildings while in other cases a berlin wall should be constructed. 2. evaluating criteria priorities by the method of entrophy it is clear when there is a building near a retaining wall the most significant theoretical criteria are seasonal prevalence and installation duration, the most important complex criterion is installation duration. otherwise, when there is no building next to the retaining wall, both theoretical and complex creteria are the operating costs of the equipment. 3. the multi-criteria evaluation by the method of utility value found that a rational wall installation version is a pile wall when it is installed adjacent to existing buildings. the berlin wall is the most rational version of retaining wall installation with no adjacent buildings table 6 degree of utility for each alternative solution using entropy technique alternatives options a1 a2 a3 case 1 retaining walls with ground anchors in sandy ground with a high level of ground water degree of utility options, % 100.0 7.2 89.2 case 2 ret. walls with ground anchors installed close to existing buildings in sandy ground with a high level of ground water degree of utility options, % 72.1 100.0 46.2 case 3 retaining walls with ground anchors in sandy ground (without ground water and a building in close proximity) degree of utility options, % 100.0 0.4 78.1 case 4 retaining walls with ground anchors in sandy ground (without water) close to existing buildings) degree of utility options, % 48.9 100.0 34.1 case 5 retaining walls with ground anchors in clay ground degree of utility options, % 100.0 9.1 73.0 case 6 retaining walls with ground anchors in clay ground close to existing building degree of utility options, % 68.7 100.0 52.0 conclusions fig. 3 illustrates the best rational solutions of retaining wall computation schemes. in fig. 3 the computation scheme of sheet wall was not given because in all investigated cases (table 6) this type of retaining wall was not a rational solution. journal of sustainable architecture and civil engineering 2020/1/26 64 aarsleff. http://www.aarsleff.com.pl/lt/pasilymas, [interactive]. 2016. arcelormittal piling handbook 8th edition, 2008, available at http://sheetpiling.arcelormittal.com/ uploads/files/arcelormittal%20piling%20handbook_rev08.pdf byfield m.p., mawer r. w. analysis of reduced modulus action in u-section steel sheet piles. journal of constructional steel research, 2004; 60: 401-410. https://doi.org/10.1016/s0143-974x(03)00119-6 day r.w. geotechnical and foundation engineering. design and construction. new york: mcgraw hill professional, 1999, 750 p. el-nagar m.e. enhancement of steel sheet-piling quay walls using grouted anchors. journal of soil science and environmental management, 2010; 1(4): 69-76. gil-martín l.m., hernández-montes e., aschheim m. optimization of piers for retaining walls. structural and multidisciplinary optimization, 2010; 41(6): 979987.https://doi.org/10.1007/s00158-010-0481-2 references katkevičius l, baublys r. construction of waterways, quays and embankments. kaunas: ardiva. 2008. 77 p. (in lithuanian). konstantakos d.c. advantages and limitations of ultimate limit state design methods for braced excavations. earth retention conference (er), august 1-4, bellevue, washington, united states, 2010: 818-820. https://doi.org/10.1061/41128(384)82 kreišmantas a. analysis of stress and deformation of steel sheet walls on tension forces of anchor. 2016. 63 p. (in lithuanian). en 1536:2000. execution of special geotechnical work bored piles. merifield r.s., lyamin a.v., sloan s.w., yu h.s. three-dimensional lower bound solutions for stability of plate anchors in clay. journal of geotechnical and geoenvironmental engineering, 2003; 129(3): 243-253. https:// doi.org/10.1061/(asce)1090-0241(2003)129:3(243) van baars s. design of sheet pile installation by vibration. geotechnical and geological engineering, 2004; 22(3): 391-400. https://doi.org/10.1023/b:gege.0000025047.17363.f8 mindaugas žagarinskas engineer uab “projektana” main research area civil engineering. address chemijos str. 23d, lt-51331 kaunas, lithuania tel. +370 37 300473 e-mail: mindaugas.zagarinskas@ projektana.lt mindaugas daukšys dr. faculty of civil engineering and architecture main research area civil engineering, construction technology. address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: mindaugas.dauksys@ktu.lt jūratė mockienė master faculty of civil engineering and architecture main research area civil engineering. address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: jurate.mockiene@ktu.lt about the authors https://doi.org/10.1016/s0143-974x(03)00119-6 https://doi.org/10.1007/s00158-010-0481-2 https://doi.org/10.1061/41128(384)82 https://doi.org/10.1061/(asce)1090-0241(2003)129:3(243) https://doi.org/10.1061/(asce)1090-0241(2003)129:3(243) https://doi.org/10.1023/b:gege.0000025047.17363.f8 https://doi.org/10.1023/b:gege.0000025047.17363.f8 mailto:mindaugas.zagarinskas@projektana.lt mailto:mindaugas.zagarinskas@projektana.lt mailto:mindaugas.dauksys@ktu.lt mailto:jurate.mockiene@ktu.lt 23 journal of sustainable architecture and civil engineering 2017/4/21 *corresponding author: olagokeseyi@yahoo.com evaluating building sustainability literacy level in nigerian architectural education received 2017/09/04 accepted after revision 2017/12/29 journal of sustainable architecture and civil engineering vol. 4 / no. 21 / 2017 pp. 23-28 doi 10.5755/j01.sace.21.4.18620 © kaunas university of technology evaluating building sustainability literacy level in nigerian architectural education jsace 4/21 http://dx.doi.org/10.5755/j01.sace.21.4.18620 oluseyi a. olagoke* mustards architectural concept, oshogbo, nigeria olusola o. bamisile cyprus international university, nicosia introduction sustainability has become a qualifying factor in every human endeavor and architectural educators could really not care less in ensuring a holistic education premised on the tenets of both conscientious and discretionary use of the ever-depleting natural resources much of which is morally right to be left for yet many future generations. also, since a good proportion of architecture graduates from nigerian tertiary institutions end up as teachers in architecture departments, it becomes important to understand the level of their knowledge of the concept of building sustainability while in school as understanding this could be helpful in positioning them to be better architectural educators. this research hence focuses on six selected departments of architecture and architectural technologies in tertiary institutions in southwest nigeria and the aim is to establish whether the concept of sustainability is well taught and understood both by architectural educators and students. open and close-ended questionnaires were distributed to students and the results are analyzed using statistical tools. consequently, findings derived from this survey are hoped to help inform a set of recommendations aimed at enhancing improved knowledge acquisition by these teaming future professionals thus ensuring a holistic and balanced training and education necessary for proper entrenchment of the much needed sustainability consciousness and awareness in nigeria. keywords: architectural education, building sustainability, literacy level, southwest nigeria. if the principles of a sustainable environment are to be well entrenched, the role of educational institutions cannot be downplayed but it is a general opinion that there is no definite framework to foster this in architecture curricula. less can surely be said of other “related” departments in nigerian schools of higher learning (shari and mohd, 2006). so, examining the content of the current curriculum and enforcing necessary alterations as the tenets of building sustainability will require (in the context of nigeria’s geographical peculiarities) is itself needful (james 2003). responsible and well informed designers are the only select few that possess both the competency and initiatives to deliver responsible designs and it is only logical to assert that such knowledge could mostly be gotten from academic institutions and environments sometimes also as apprentice to well-established professionals. roles of architects in managing environmental degradations, deforestation, climate change, waste management and other means of natural resources exhaustion cannot be over-emphasized; but it quietly becomes worrisome if and when these individuals journal of sustainable architecture and civil engineering 2017/4/21 24 are grossly incapacitated both by inadequate training and lack of necessary exposures. this is the current situation in southwest nigeria where rapid physical infrastructural and developmental activities are currently ongoing. this research aims to ascertain the omission of architectural sustainability knowledge and awareness level as indicated in the taught curriculum of architectural education in nigeria’s tertiary institutions. according to the joint admissions and matriculation boards (jamb, 2017) the government agency saddled with the responsibility of regulating the process of admitting students to tertiary institutions in nigeria, there currently are thirty-six polytechnics and thirty-five universities offering architecture or architectural technology as the case may be in the country. of these, twelve polytechnics (i.e. 33.3%) and eleven universities (i.e. 31.4%) are located in the six south-western states of ekiti, lagos, ogun, ondo, osun, and oyo. this, invariably, is the geo-political region with the highest concentration of institutions offering architecture degrees in all of the country hence making it an ideal location to survey sustainability literacy level among its current architecture students. also, according to m. adegbile (2012), the highest concentration of registered architects in nigeria, is in lagos, the commercial capital of nigeria. so, the set of states in this region are arguably at the most risk of adverse environmental set-backs if a bulk of these architecture graduates prove to be incompetent in handling issues germane to general sustainability principles such as is happening in most part of the developed world. of the said number of institutions, three universities and three polytechnics were surveyed in 2017 with responses from 139 students. the six institutions which include ladoke akintola university of technology, federal university of technology, akure, obafemi awolowo university, federal polytechnic, ede, moshood abiola polytechnic, and osun state college of technology spread across oyo, osun and ondo states. these schools were chosen because they were among those in session between may and june when the questionnaires were sent out; only undergraduate students from year one to year four were assessed. the preferred methodology used for this research is quantitative quasi-experimental (groat and wang, 2002). questionnaires were distributed both to both male and female students in order to determine, assess and evaluate their level of understanding and also to identify their concept of building sustainability; added to this random semi-structured elite interviews were carried out. further evaluations of all relevant assessments are analyzed and these all combine to inform carefully made recommendations and conclusion. justification of study location and research methodology literature review environmental literacy and architectural mediocrity we would describe architectural mediocrity as the state of lack of mental alertness and creativity by architects and that often pre-disposes them to performing below expectations in their professional practice. since sustainable design safely describes as providing housing and building solutions that have little or no adverse impact on the very localized environment, it thus becomes imperative to pay attention to understanding the environment and how best to manage its resources and here comes in the essence of environmental literacy. m. adegbile (2012) explained the drabness and apparent lack of architectural sustainability content in the core of the study curricula of architecture departments in all of nigerian institutions. he attributed this to the lack of willingness to make an appraisal of how the not-too-distant past iconic traditional pre-colonial architecture thrived in our environmental context and how post-colonial architecture on the other hand seemingly has got no regard for our geography. environmental awareness predates environmental responsiveness and these both begot environmental sustainability. so, exclusive consideration for just animate objects will not only be unfair but also ill-intentioned in the quest for any society to be environmentally responsive. this makes 25 journal of sustainable architecture and civil engineering 2017/4/21 both long and short term decisions that adequately consider the wellbeing of other environmental entities like sun, rivers, air and sky as such very desirable. also, in a geo-political setting where there are palpable missing links in policy formation and implementation, individuals are often left to the use of subjective and simple discretions in their modus operandi; this is obviously short of best practice as it will be an upheaval task to dare single-handedly or at best impulsively spearhead a principle that directly challenges established status quo (gardner and stern, 2002). this inertia is hard to overcome! in nigeria, relevant organizations and governmental agencies whose oversight include managements, registration and accreditation of universities’ and polytechnics’ courses are rather implored to take responsibility for including active sustainability components into building construction-related courses and especially architecture. understanding the concept of building sustainability in nigeria currently, improvement on physical infrastructure and building is a major concern to all developing countries (bardhan and mookherjee, 2006) such as nigeria (ibrahim, 2016) as a result of its understandable rapid rate of population growth; it is then of serious concern how the country goes about meeting this need in view of the current arguably weak policies on green building and sustainability. beyond formulating policies, incorporation of holistic frameworks hinged upon localized and relevant best practices rather than importing such from other societies would be desirable. replicating great construction progresses made globally is undoubtedly ideal as it is a goal of building practitioners in nigeria which is typical of all emerging countries; but the possibility of achieving this any time soon in a sustainable manner is perhaps non-existent as a result of some of the factors earlier mentioned such as weak government institutions, dearth of expertise and unfavorable regulatory framework (othman, 2013). whereas addressing these issues is quite as multi-faceted as the problems itself, yet, ascertaining the perceived environmental awareness of architecture students of building sustainability and sustainable construction in itself is as vital as other approaches. there is still much to be understood especially with the current lack of a cohesive understanding in the definition of building sustainability as seen in the problem statement. when there is no consensus on a problem definition, divergent approaches in solving such overwhelming related problems are inevitable; unfortunately, there will be little or no results to show for whatever effort is channeled without a concise sense of direction. discussions and results impact of current living conditions on students’ sustainability awareness there is no over-flogging the long established thought that suggests the impact that our environment has in forming our worldview and intricate opinion on issues of equal concern to others. this survey equally takes a dive into understanding if the current accommodation of all responders has ever endeared them to thinking green. building climatology and building physics, orientation, natural lighting and natural ventilation are instinctively elementary elements of green design that most architecture students are at least expected to be familiar with and their responses show how divergent their understandings on this are. similarly, the non-enforcement of building codes that stipulate minimum requirements for sustainable building elements is obviously missing in both state and local building planning regulations in most parts of nigeria: this then calls for concern as many of the respondents already resumed the process of ‘semi-professional’ indoctrination while in school. so, coupled with the fact that almost nothing in their current built environment is strong enough to sensitize them on building sustainability, the building practices they are already exposed to in the early and formative stage of their professional career is also grossly deficient (ajah and isaiah, 2016). therefore, if this is not holistically looked into, this undesired trend will simply continue. as an environmental factor that will refuse to be waived off, of paramount and equal importance then is understanding the disposition of (potential) clients to building sustainability and green journal of sustainable architecture and civil engineering 2017/4/21 26 architecture. interestingly, the simple logic of a repeated cycle plays itself out here: there are no green buildings around; architects are ignorant of its concept and principles; there are no regulations insisting of green components to be included in any proposed building design and then there are no clients interested in environmental sustainability. so, very important is understanding which one comes first and overcoming the inertia in addressing the others. its ironical to realize one obvious palpable reason for the seeming lack of interest by building designers to use sustainable building elements (which are usually locally-sourced building materials); the usual preference is for contemporary building materials which generally are not locally produced and hence contribute in no little way to environmental pollution directly or indirectly because of their non-reusability and non-recyclability. the usual justification for this is rather merely premised on the fact that it shows improved societal status. whereas the essence of sustainable building includes the usage of traditional building materials, current building trends in the developed world can still be of huge relevance provided local architects understand how best to incorporate these to produce sustainable results. in doing this, understanding efficient waste and water management, energy efficiency, the relevance of green roof and rain gardens alongside conscious awareness of building climatology cannot be over-emphasized (ajah and isaiah, 2016). table 1 overview of responses from the respondents questions percentage yes no not sure 1. are you aware of the concept/principles of building sustainability? 74.7 11.3 14.0 2. are there perceived elements of building sustainability in the physical infrastructure of your school? 52.7 24.0 23.3 3. are there elements of building sustainability in the architectural curriculum of your school? 71.3 14.7 14.0 4. with regards to your studio design courses, do you attempt to incorporate the elements/principles of building sustainability into your works? 80.0 9.3 10.7 5. as an architect, do you incorporate the principles of building sustainability into your design projects? 56.7 35.3 8.0 6. since environmental literacy and sustainability literacy can be difficult to separate, could you then say that your personal knowledge of our environment suggests an urgent need to conserve all natural resources? 72.7 4.0 23.3 7. have you been offered any sustainability course in your school? 69.3 30.7 8. could you assert that your current residence has a direct influence on your perception of building sustainability? 38.0 30.7 31.3 9. are you personally concerned about building sustainability? 86.0 8.7 5.3 10. will you recommend that more courses on building sustainability be introduced into architecture curriculum? 84.7 11.3 4.0 11. how will you rate the level of sustainability and environmental literacy level in your institution? average 14.0 above average 72.0 below average 14.0 assessing current sustainability awareness level of nigerian architecture students surprisingly, the apparent danger of misconception is a formidable force worth giving some attention it deserves as realized quite recently. it is pathetic that a good number of architecture students (78.2%) opined that they understand what building sustainability is but failed to justify this position when probed further. a staggering 23.3% remain indifferent as to the urgency of learning 27 journal of sustainable architecture and civil engineering 2017/4/21 more improved mechanisms of better enhancing environmental literacy level. this again raises some further concerns that highly question the intellectual integrity of their tutors on one side and also that of the validity and continued relevance of architecture curriculum. curiously, 13.5% of the respondents insist that environmental and sustainability literacy level in their schools is much below average thus leaving much to be desired. in fact, many (i.e. 27.6%) admitted have never been offered any building sustainability course. it is relieving however learning that 90.1% of the respondents recommend that more building sustainability courses be introduced into the architecture curriculum if nigeria will ever stand shoulder-to-shoulder with other environment-conscious developed and developing countries. as the case currently is, the challenge or desire to invent creative means of solving environmental problems through responsive building designs is conspicuously missing as half-baked architects may end up causing more damage instead; this again is evident in the 29.2% of the surveyed student admitting their lack of motivation in incorporating the rather uninteresting sustainable elements taught into their design projects. worse still, a fair percentage of them (i.e. 30.7%) are not sure whether their course contents are in any way tailored towards environmental and building sustainability. except the needful is done, the challenges of architectural and building sustainability will soon become unbearable and a majority of the locally trained architects will unfortunately not be able to meet up with these expectations. this becomes yet more worrisome as the role of the professionals in the built environment in ensuring that nigeria meets her long-term developmental goals cannot be achieved. the assertion of a. o. olutuah and o. s. adesiji (2005) that “the programmes of schools of architecture in nigeria lead to the production of professionals who are sensitive to human needs and aspirations and who have the requisite knowledge and the intellectual and aesthetic skills to evolve expressive design solutions of problems of the built environment” is thus rather arguable for reasons of subjectiveness. it is perhaps easier to believe that sustainability-conscious nigerian architecture graduates are rather self-taught than being a direct product of the architecture curricula of nigerian schools of architecture. ignoring the reality of green architecture in any given geography means endangering the future of the built environment of such place. there is neither gainsaying nor over-emphasizing the need to address sustainability deficiencies in nigerian architectural education and practice (adeyemi, 2000; uji, 2001; dare-abel, 2015). this is directly related to the content of the prevailing teaching curriculum in our architecture schools. policy formation and implementation, project monitoring, funding and training and retraining are all key components to work upon in order to sufficiently initiate robust and exhaustive sustainable development innovations (sdi) in nigeria. once properly looked into, regardless of the shortage of professional architects in the country, the role of architectural technicians and draughtsmen who themselves pose viable threats to school-trained architects and architectural technologists will also be adequately defined. whereas traditional architecture is a lot sustainable, the reluctance to allow prevailing international norms and standards to partly suggest a remodeling of nigeria’s architecture curriculum from its pre-independence philosophies leaves much to be desired. in ameliorating this dilemma, the need for pilot projects can also not be over-emphasized as it helps in understanding the peculiarities of the nigerian environment. it is also observed that the national universities commission and the national board for technical education both are the sole bodies that formulate and regulate the curricula of universities and polytechnics respectively; so, well-tailored refresher courses aimed at exposing the relevant architecture experts and consultants to current trend in sustainability principles, theories and practices will be highly desired. conclusions journal of sustainable architecture and civil engineering 2017/4/21 28 it is also recommended that the concept of passive 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101-127. https://doi.org/10.1111/j.14680297.2006.01049.x dare-abel o. a. pathways to architecture education and practice success in nigeria. journal of education and practice, 2015; 4(6): 169-175. gardner, g.t.,stern, p.c.. environmental problems and human behavior (2nd ed.). boston, m. a. pearson custom publishing; 2002. groat l. n., wang d. architectural research methods. new york: j. wiley; 2002, p 176. ibrahim m. factors contributing to poor performance in construction projects: studies of saudi arabia. australian journal of multi-disciplinary engineering, 2016; 1(12): 27-38. joint admissions and matriculations board (jamb). brochure, 2017. (accessed 09 july 2017) available at: http://www.jamb.gov.ng/brochure.aspx. olotuah, a. o., adesiji, o. s. housing poverty, slum formation, and deviant behavior. papers and presentations, the housing studies association conference, university of lincoln, lincoln, uk, 8-9 september, 2005. (accessed 09 july 2017) available at:www.lincoln.ac.uk/home/conferences/details/ has /paperolotuah.doc. othman a. a. e. challenges of mega construction projects in developing countries. organization, technology & management in construction: an international journal, 2013; 1(5): 730-746. https:// doi.org/10.5592/otmcj.2013.1.10 shari z., mohd f. k. j. towards a more sustainable architecture education in malaysia. journal of tropical design research and practice, 2006; 1(1): 57-64. uji a. z. 2001. beyond the critiques of the curriculum of architectural education in nigeria. in u. o. nkwogu (ed.) architects and architecture in nigeria – a tribute to prof. e. a. adeyemi. akure: aarches, shalom publishers; 2001, pp. 109-122. oluseyi a. olagoke architect mustards architectural concept main research area architectural conservation and building sustainability address zone g/#18, adesoji aderemi by-pass, oshogbo, nigeria tel. +234 703 700 0434 e-mail: olagokeseyi@yahoo.com, oaolagoke@mustarc.com.ng olusola o. bamisile research assistant common courses unit cyprus international university, nicosia address tel. +90 548 848 86 48 e-mail: boomfem@gmail.com about the authors references 73 journal of sustainable architecture and civil engineering 2017/1/18 corresponding author: alban.ogbonna@yahoo.com strength properties of hydraulic cement concrete pavement incorporating coconut shell as coarse aggregate received 2016/11/29 accepted after revision 2017/01/18 journal of sustainable architecture and civil engineering vol. 1 / no. 18 / 2017 pp. 73-80 doi 10.5755/j01.sace.18.1.16664 © kaunas university of technology strength properties of hydraulic cement concrete pavement incorporating coconut shell as coarse aggregate jsace 1/18 http://dx.doi.org/10.5755/j01.sace.18.1.16664 ogbonna alban chidiebere*, abubakar mikailu department of civil engineering, waziri umaru federal polytechnic, birnin kebbi, p.m.b 1034 birnin kebbi g.p.o, birnin kebbi city, kebbi state, nigeria introduction coconut shell being a hard and not easily degradable material if crushed to size of coarse aggregate can be a potential material to replace coarse aggregate in concrete. in this study the characteristics of the coarse aggregate and the coconut shell were evaluated. properties of fresh and hardened concrete with partial replacement of coarse aggregate with coconut shell were also studied. concrete specimens with 0%, 5%, 10%, 15% and 20% by weight of coarse aggregate replacement with coconut shell were made at 1:2:4 mix ratio. the compressive strength for all the concrete specimens was evaluated at 7, 14, 21 and 28 days and constant water cement ratio of 0.5 was maintained for all the concrete specimens. the aggregate crushing value of the coarse aggregate and the coconut shell were 23.47% and 28.25% respectively and the aggregate impact value of the coarse aggregate and the coconut shell were 17.44% and 20.2% respectively. the slump values, densities and compressive strength of concrete decreased as the percentage replacement with coconut shell increased. concrete produced with 0%, 5%, 10%, 15% and 20% replacement attained 28 days compressive strength of 38.17, 35.11, 32.14, 31.18, and 29.14 n/mm2 respectively. the results obtained in this study showed that coconut shell satisfied the requirements for coarse aggregate and can be used as partial replacement of coarse aggregate (up to 20%) in concrete pavement production. keywords: coarse aggregate, coconut shell, concrete pavement, cement, strength properties. there are many research works conducted to improve the engineering properties of concrete by partial or full replacement of coarse aggregate, fine aggregate or cement paste (aci 318/318r -08, 2009, gunasekaran et al, 2011, and olanipekun, 2006). cement mortar and concrete are the most widely used construction material. it is difficult to point out another material of construction which is versatile as concrete. it is the material of choice where strength, permanence, durability, impermeability, fire resistance and abrasion resistance are required. it is also closely associated with every human activity that it touches every human being in his day to day living (shetty, 2013). infrastructure development across the world created demand for construction materials. concrete manufacturing involve consumption of ingredients like cement, aggregates, water and admixtures (amarnath, and ramachandrudu, 2012, parag, and sandhya, 2014, and shetty, 2013). among all journal of sustainable architecture and civil engineering 2017/1/18 74 the ingredients, aggregates form the major part (amarnath, and ramachandrudu, 2012). it is incredibly versatile and is used in almost all major construction projects (amarnath, and ramachandrudu, 2012, parag, and sandhya, 2014, and shetty, 2013). aggregates typically consist of 60% 70% of the volume of a concrete mixture (shetty, 2013). use of natural aggregates in such a rate leads to question about the preservation of natural aggregates sources (amarnath, and ramachandrudu, 2012). in addition, operations associated with aggregate extraction and processing are the principal course of environmental concerns (osei, 2013, and shetty, 2013). the negative consequences of increasing demand of aggregates include depletion of aggregate deposits, environmental degradation and ecological imbalance (osei 2013). the possibility of a complete depletion of aggregate resources has rendered continued use of aggregates in construction works unsustainable (naik, 2008). research addressing environmental and sustainability issues in construction has generated lots of interest in the world (akshay, et al 2014, gunasekaran, et al 2011, and olanipekun, et al 2006). the use of waste materials saves natural resources and dumping spaces, and helps to maintain a clean environment, (parag, and sandhya, 2014). coconut shell being a hard and not easily degradable material if crushed to size of coarse aggregate can be a potential material to substitute coarse aggregate in concrete (akshay et al, 2014, gunasekaran, et al 2011, and olanipekun, et al 2006). according to olanipekun, et al (2006) and gunasekaran, et al (2011), limited research has been conducted on mechanical properties of concrete with coconut shell as aggregate replacement. coconut shells are agricultural waste produced as by products of coconut oil production (osei, 2013). the potential of using agricultural wastes in civil engineering works have been investigated by various researchers. in a study, olanipekun et al, (2006) compared concrete made with coconut shells and palm kernel shells as replacement for natural coarse aggregates and concluded that coconut shells performed better than palm kernel shells as replacement for conventional aggregates in concrete pavement. in an experimental assessment on coconut shell as aggregate in concrete, osei, (2013) concluded that 18.5% replacement by volume of crushed granite with coconut shell can be used to produce structural concrete in line with bs 8110. the coconut shell aggregate has higher water absorption because of higher porosity in its shell structure (gunasekaran et al, 2011, kakade, and dhawale, 2015, and olanipekun et al, 2006). the aggregate impact value of coconut shell aggregate is much lower compared to crushed aggregate which indicates that this aggregate have good absorbance to shock (kakade, and dhawale, 2015). in a study parag, and sandhya, (2014) concluded that the coconut shell has potential as light weight aggregate in concrete and using the coconut shell as aggregate in concrete can reduce the material cost in construction because of the low cost of abundant agricultural waste. they suggested that coconut shell concrete can be used in rural areas and places where coconut is abundant and may also be used where the conventional crushed aggregates are costly. in a study akshay et al, (2014) concluded that coconut shell aggregate concrete satisfied the requirements of astm c330/c330m-14 (2014). they have it that to increase the speed of construction, enhance green construction environment, we can use lightweight concrete. the possibility exists for the partial replacement of coarse aggregate with coconut shell to produce light weight concrete. this research work is aimed at assessing the strength properties of hydraulic cement concrete pavement incorporating coconut shell as coarse aggregate. the major objectives of this work are: to examine the properties of concrete pavement produced by partial replacement of coarse aggregate (crushed granites) with coconut shell at different percentages and to enlighten the relevant agencies, professional bodies, consultancy and construction firms on the potential use of coconut shell in concrete production. 75 journal of sustainable architecture and civil engineering 2017/1/18 cement the hydraulic cement used in this study conform with the specifications of astm c150/ c150-16 e1 (2016) astm c1157/c1157m-11 and aashto m85 (2016). aggregates aggregates were selected in accordance with aashto (2013, 2015), astm 127-15 (2015), astm d448 (2012), astm c33/c33m (2013), astm c29/c29m (2016), astm c330/c330m-14 (2014), wsdot m46-01.15 (2013), wsdot m46-01.24 (2016), and wsdot m41-10 (2013). crushed granites passing through sieve 25mm but retained in sieves 19 mm, 12.5mm, 10mm and 4.75mm was used as coarse aggregate. coconut shell was obtained locally and crushed into smaller sizes passing through sieve 25mm but retained on sieve 19 mm, 12.5mm, 10mm and 4.75mm. the coconut shell aggregate were air dried for 21 days. fibre and husk on dried shells were carefully removed. mix design table 1 shows the design mix used for this study. the concrete specimens were prepared at the mix ratio of 1:2:4 by weight and marked as shown in table 1. the control mix (g1) with 0% coconut shell was prepared. subsequently samples g2, g3, g4 and g5 were prepared with 5%, 10%, 15% and 20% replacement by weight of coarse aggregates with coconut shell. materials and methods table 1 design mix for the concrete specimens concrete specimen mark percentage replacement with coconut shell (%) cement content (kg/m3) fine aggregate content (kg/m3) coarse aggregate content water cement ratio (%) crushed granite (kg/m3) coconut shell (kg/m3) g1 0 357 714 1428 0 0.5 g2 5 357 714 1356.6 71.4 0.5 g3 10 357 714 1285.2 142.8 0.5 g4 15 357 714 1213.8 214.2 0.5 g5 20 357 714 1142.4 285.6 0.5 sieve analysis combined sieve analysis was conducted for fine aggregate, coarse aggregate and coconut shell in accordance with aashto (2013, 2015), astm c136/c136m-14 (2014), astm d6913-04 (2009), astm d448 (2012), wsdot m46-01.15 (2013), wsdot m46-01.24 (2016), and wsdot m41-10 (2013). the sieve analysis involves the passing of original samples through a stack of sieves arranged in descending order of the openings of the sieves, with larger sieves on the top. the materials retained on each sieve after shaking, represents the fraction of the aggregates coarser than the sieve in question and finer than the sieve above. aggregate impact value (aiv) test the aggregate impact value test gives relative measure of the resistance of an aggregate to sudden shock or impact (udoeyo, and dashibil, 2002). the aggregate impact value (aiv) was conducted for the coarse aggregate and the coconut shell in accordance with aashto (2013, 2015), astm d5874-02 (2007), astm c131/c131m-14 (2006), wsdot m46-01.15 (2013), and wsdot m46-01.24 (2016). aggregate crushing value (acv) test the aggregate crushing value gives a relative measure of the resistance of an aggregate to crushing under a gradually applied compressive load (shetty 2013). the aggregate crushing value test journal of sustainable architecture and civil engineering 2017/1/18 76 was conducted for both coarse aggregate and coconut shell in accordance with astm d5874 – 02 (2007), astm c131/c131m -14 (2006), astm c192/ 192m -15 (2015), and wsdot m46-01.24 (2016). slump test according to aashto (2013), aashto (2015), bsen 12350-02 (2009), bsen 206-1(2006)], the slump test is a measure of the consistency of the concrete and a change in the slump test indicates that something in the manufacturing of the concrete has changed. slump test was conducted on the fresh concrete in accordance with [aashto (2013, 2015), astm c143/c143m -15 (2015), astm c1611 (2015), wsdot m46-01.15 (2013), and wsdot m46-01.24 (2016)]. compressive strength test compressive strength test was performed on the hardened concrete in accordance with aashto (2013, 2015), aci 318/318r, astm c495/c495m (2012), wsdot m46-01.15 (2013), wsdot m4601.24 (2016), and wsdot m41-10 (2013). the test specimens were of the size 150 mm x 150 mm x 150 mm. the filling of the moulds was in three layers of 50mm each. the concrete cubes were compacted manually using 16mm diameter rod at 40 evenly distributed strokes per layer. the samples were marked and cured in clean fresh tap water and were maintained at a room temperature. three specimens from each of the five different mixes were crushed at 7, 14, 21 and 28 days age respectively and the average compressive strength were recorded. aggregates characteristics the results of the combined gradation of coarse aggregate, coconut shell, and fine aggregate are shown in table 2. the results of the physical and mechanical properties of the coarse aggregate, fine aggregate and coconut shell are shown in table 3. these properties conform to the requirements of coarse aggregate for concrete pavement in accordance with astm d5874 – 02 (2007), astm c131/ c131m -14 (2006), astm 127 -15 (2015), astm d448 (2012), astm c33/c33m (2013), astm c330/ c330m-14 (2014). results and discussion table 2 combined aggregate gradation (fine aggregate, coarse aggregate and coconut shell) sieve size (mm) percentage retained (%) cumulative percentage retained (%) percentage passing /finer (%) 25 0.00 0.00 100.00 19 4.18 4.18 95.82 12.5 17.84 22.02 77.98 9.5 15.11 37.13 62.87 4.75 12.81 49.94 50.06 2.36 8.88 58.82 41.18 1.18 9.78 68.60 31.40 0.6 1.16 80.76 19.24 0.3 7.48 88.24 11.76 0.15 5.20 93.44 6.56 0.075 4.26 97.70 2.30 table 3 physical and mechanical properties of fine aggregate, coarse aggregate and coconut shell properties fine aggregate coarse aggregate coconut shell specific gravity 2.6 2.70 1.63 water absorption (%) 1.11 2.1 4.48 aggregate crushing value (%) 23.47 28.25 aggregate impact value (%) 17.44 20.20 77 journal of sustainable architecture and civil engineering 2017/1/18 properties of concrete incorporating coconut shell table 4, shows the slump, density and compressive strength values of concrete at different percentage replacement of coarse aggregate with coconut shell. the slump decreased with increase in coconut shell percentage. the control mix with 0% coconut shell showed higher compressive strength. furthermore, the compressive strength decreased with coconut shell percentage increase. fig. 1 shows the relationship between 28 day and 56 day compressive strength with percentage replacement of coarse aggregate with coconut shell. fig. 2 shows the relationship specimen mark percentage replacement of coarse aggregate with coconut shell (%) slump (mm) density (kg/m3) average compressive strength (n/mm2) 7 day 14 day 21 day 28 day 56 day m1 0 83 2490 26.84 31.87 35.11 38.17 42.22 m2 5 77 2467 23.67 28.01 33.08 35.11 41.54 m3 10 63 2348 21.01 25.04 29.78 32.14 38.65 m4 15 60 2380 19.18 23.66 25.11 31.18 35.23 m5 20 57 2336 17.11 21.17 23.18 29.14 33.06 table 4 properties of concrete incorporating coconut shell as partial replacement of coarse aggregate fig. 2 relationship between the average compressive strength with curing age 0 5 10 15 20 25 30 35 40 45 7 day 14 day 21 day 28 day 56 daya ve ra ge c om pr es si ve s tr en gt h (n /m m 2 ) curing age (days) 0% 5% 10% 15% 20% fig. 1 relationship between 28 day and 56 day compressive strength and percentage replacement with coconut shell 38 35 32 31 29 42.22 41.54 38.65 35.23 33.06 0 10 20 30 40 50 0 5 10 15 2028 a nd 5 6 da ys c om pr es si ve st re ng th (n /m m 2) percentage replacement of coarse aggregate with coconut shell (%) 28 day 56 day journal of sustainable architecture and civil engineering 2017/1/18 78 conclusion and recommendations between compressive strength and age of the concrete specimens. there were good relationships between these variables. the results conformed to the specifications of aashto (2013, 2015), aci 318/318r, astm c495/c495m (2012), wsdot m46-01.15 (2013), wsdot m46-01.24 (2016), and wsdot m41-10 (2013). based on the results and discussions presented in this research, the following conclusions were drawn; 1 the use of coconut shell in concrete pavement production will contribute to resource con-servation of natural aggregate, environmental protection and reduction in the cost of construction since this agricultural waste can be obtained at little or no cost. 2 coconut shell characteristics satisfied the requirement for concrete coarse aggregate and can be used as partial replacement of coarse aggregate in concrete production in accordance with astm d5874-02 (2007), astm c131/c131m -14 (2006), astm 127-15 (2015), astm d448 (2012), astm c33/c33m (2013), astm c330/c330m -14 (2014), wsdot m46-01.15 (2013), wsdot m46-01.24 (2016), and wsdot m41-10 (2013). 3 the properties of concrete incorporating up to 20% coconut shell aggregate satisfied the minimum requirement of 28 n/mm2 for 28 days compressive strength for standard concrete pavement as specified by astm d5874-02 (2007), astm c131/c131m -14 (2006), astm 127-15 (2015), astm d448 (2012), astm c33/c33m (2013), astm c330/c330m -14 (2014), wsdot m46-01.15 (2013), wsdot m46-01.24 (2016), and wsdot m41-10 (2013). 4 percentage increase in coconut shell replacement reduces the compressive strength, den-sity and slump values of concrete. 5 developing counties should encourage the use concrete pavement and structural concrete incorporating coconut shell up to 15% by weight of coarse aggregate as a construction cost reduction measure and an environmental friendly construction. 6 performance of coconut shell concrete in heavy traffic pavements should be carried out by future researchers. 7 standard concrete pavement produced at 1: 2: 4 mix ratios satisfied the minimum cementi-tious content of 215 kg/m3 which is a function of durability as specified in pca is415. aashto. standard specifications for transportation materials and methods of sampling and testing, 33rd edition. american association of state highway and transportation officials, washington, dc, usa. 2013; http://www.transportation.org. aashto. standard specifications for transportation materials and methods of sampling and testing, 35th edition. american association of state highway and transportation officials, washington, dc, usa. 2015; http://www.transportation.org. aashto m85-16, standard specification for portland cement . american association of state highway and transportation officials, washington, dc, usa. 2016; http://www.transportation.org. aci 318/318r -08, building code requirements for structural concrete and commentary; aci committee 318. american concrete institute, farmington hills, mi. usa. 2009; http://www.concrete.org/318. htm. akshay, s.s., kalyami r.n., pooja p.k, and shraddha p.g. “coconut shell as partial replacement for coarse aggregate review”, international journal of civil engineering research, 2014; vol. 5(3): pp 211214. amarnath, y. and ramachandrudu, c. “properties of concrete with coconut shells as aggregate replacement”, international journal of engineering inventions, 2012; vol. 1 (6), pp 21-31. astm c136/c136m-14. standard test method for sieve analysis of fine and coarse aggregates, astm international, west conshohocken pa. 2014; http:// www.astm.org. references 79 journal of sustainable architecture and civil engineering 2017/1/18 astm d6913-04. standard test method for particle size distribution (gradation) of soils using sieve analysis. astm international, west conshohocken pa. 2009; http:// www.astm.org. astm d5874-02. “standard test method for determination of the impact value (iv) of a soil”. astm international, west conshohocken pa. 2007; http:// www.astm.org. astm c131/c131m-14. standard test method for resistance to degradation of small size coarse aggregate by abrasion and impact in the los angeles machine, astm international, west conshohocken pa. 2006; http:// www.astm.org. astm c1157/c1157m-11, standard specification for hydraulic cement. astm international, west conshohocken pa. 2011; http:// www. astm.org. astm c150/150m-16e1, standard specification for portland cement. astm international, west conshohocken pa. 2016; http:// www.astm.org. astm c143/c143m -15. standard test method for slump of hydraulic cement concrete. astm international west conshohocken, pa. 2015; http://www.astm.org. astm c1611. standard test method for slump flow of self consolidating concrete. astm international, west conshohocken, pa.2015; http:// www.astm.org. astm c94/c94m -15a. standard specification for ready mixed concrete. astm international, west conshohocken, pa. 2015; http://www. astm.org. astm 127-15. standard test method for relative density (specific density) and absorption of coarse aggregates. astm international, west conshohocken, pa. 2015; http://www.astm.org. astm c192/c192m -15. standard practice for making and curing concrete test specimens in the laboratory. astm international, west conshohocken, pa. 2015; http:// www.astm.org. astm d448. standard classification for sizes of aggregates for road and bridge construction. astm international, west conshohocken pa. 2012; http://www.astm.org. astm c33/c33m -13. standard specifications for concrete aggregate. astm international, west conshohocken pa. 2013; http://www. astm.org. astm c29/c29m. standard test method for bulk density (unit weight) and voids in aggregates. astm international, west conshohocken pa. 2016; http://www.astm.org. astm c495/c495m -12. standard test method for compressive strength of lightweight insulating concrete. astm international, west conhohocken, pa. 2012; http://www.astm.org. astm c330/c330m – 14. standard specification for lightweight aggregates for structural concrete. astm international, west conshohocken pa. 2014; http:// www.astm.org. gunasekaran, k., kumar, p.s., and lakshmipathy m. “mechanical and bond properties of coconut shell concrete”, construction and building materials, 2011; vol. 25(1), pp 92-98. https://doi.org/10.1016/j.conbuildmat.2010.06.053 kakade, s.a and dhawale, a.w. “light weight aggregate concrete shell”, international journal of technical research and applications, 2015; vol. 3 (3), pp 127 -129. naik, t.r. “sustainability of concrete construction”, practice periodical on structural design and construction”, 2008; vol. 13(2), pp 98 -103. https://doi.org/10.1061/ (asce)1084-0680(2008)13:2(98) olanipekun, e.a, olusola, k.o and ata, o. “a comparative study of coconut shell and palm kernel shell as coarse aggregates”, journal of building and environment, 2006; vol. 41 (3), pp 297 -301. https://doi.org/10.1016/j.buildenv.2005.01.029 osei, d.y. “experimental assessment on coconut as aggregate in concrete”, international journal of engineering science invention, 2013: vol. 2 (5), pp 07 -11. parag, s.k and sandhya r.m. “application of coconut shell as coarse aggregate in concrete: a technical review”, international journal of engineering research and applications, 2014; vol. 4 (3), pp 498-501. shetty, m.s. “concrete technology – theory and practice”, 16th edition, s. chand and company limited, new delhi, india; 2013. udoeyo f.f and dashibil p.u. “saw dust ash as concrete materials”, journal of materials in civil engineering, 2002; vol.14 (2), pp. 173 -176. https://doi.org/10.1061/ (asce)0899-1561(2002)14:2(173) wsdot m46 01. 15. “materials manual”. washington state department of transportationmaterials laboratory, washington d.c, usa, 2013; http://www.wsdot. wa.gov/publications/manual/m46-01.htm. wsdot m46 01. 24. “materials manual”. washington state department of transportation materials laboratory, washington d.c, usa, 2016;http://www.wsdot. wa.gov/publications/manual/m46-01.htm. wsdot m41 10. “standard specifications”. washington state department of transportation materials laboratory, washington d.c, usa, 2013; http://www. wsdot.wa.gov/publications/manual/full text/ m4110/ division9. journal of sustainable architecture and civil engineering 2017/1/18 80 alban chidiebere ogbonna lecturer/researcher department of civil engineering, college of engineering, waziri umaru federal polytechnic, birnin kebbi, kebbi state, nigeria main research area pavement material engineering, traffic engineering and transportation engineering address department of civil engineering, college of engineering, waziri umaru federal polytechnic, birnin kebbi, p.m.b 1034, birnin kebbi gpo, birnin kebbi city, kebbi state, nigeria. tel. +2348039256430 e-mail: alban.ogbonna@yahoo.com about the authors abubakar mikailu lecturer/researcher department of civil engineering, college of engineering, waziri umaru federal polytechnic, birnin kebbi, kebbi state, nigeria main research area structural engineering, foundation engineering and concrete technology address department of civil engineering, college of engineering, waziri umaru federal polytechnic, birnin kebbi, p.m.b 1034, birnin kebbi gpo, birnin kebbi city, kebbi state, nigeria. tel. +2347031276736 e-mail: mikaabuba@gmail.com journal of sustainable architecture and civil engineering 2016/1/14 20 *corresponding author: conduratmihaela@yahoo.com chains of causality associated with the environmental impact of road transport system http://dx.doi.org/10.5755/j01.sace.14.1.14658 mihaela condurat technical university „gh. asachi” from iasi, romania faculty of civil engineering and building services given the growing interest in the promotion of sustainable transport worldwide, the measurement and assessment of sustainability associated with systems and transport policies had become an increasingly important area, its measurement being performed through the environmental indicators. the paper presents the main environmental indicators assign to the road transport system and the corresponding chains of causality. also, the energy performance and the global warming potential, expressed in quantities of co2 equivalent, related to the construction and maintenance of flexible road pavements, determined based on a life cycle assessment (lca) analysis embedded in the aspect software, developed by trl laboratories, are given within this study. this paper aims to emphasize the necessity to take appropriate measures for road pavements maintenance and intervention, intended to prolong their life in order to minimize the overall ecological impact associated with the reconstruction of road pavement, which involves the release into the atmosphere of polluting emissions, usage of enormous granular materials quantities and energy consumption and thus, the exponential increase in the greenhouse effect. keywords: chain of causality, co2e emissions, environmental impact, environmental indicator, transport system. as a consequence of the alarming increase in pollution levels during the last years worldwide, the need to promote sustainable transport models had appeared. these patterns are being used for measurement and assessment of current and future trends regarding sustainability in the global concept of sustainable development. the quantification of transport systems sustainability can be performed based on environmental indicators. such indicators can be used for identify, monitor and assess environmental issues in decision making processes, as well as in comparative analysis of transport policies, plans, projects or transport technologies. an environmental indicator is defined through a parameter describing environmental state and its associated impact on human beings, ecosystems and materials, the environmental pressures, driving forces and the system responses, being determined by a complex process of selection (eea, 2009). environmental indicators differ according with the chain of causality taken into account. thus, the chain of causality represents a homogeneous process between the transportareceived 2016/04/03 accepted after revision 2016/05/30 journal of sustainable architecture and civil engineering vol. 1 / no. 14 / 2016 pp. 20-30 doi 10.5755/j01.sace.14.1.14658 © kaunas university of technology chains of causality associated with the environmental impact of road transport system jsace 1/14 introduction 21 journal of sustainable architecture and civil engineering 2016/1/14 tion system and the environmental impact final result, produced in one step or more. the chain of causality notion is being used in order to interpret the precept of “environmental mechanism”, which is defined in the life cycle impact assessment methodology through biological processes, physical and chemical specific for a particular category of impact (iso, 2006). in order to apply this chains of causality for practical assessment of transport impacts, it is necessary to perform a thorough inquiry of them and also an identification on how intermediate impacts are dependent to individual and combined variables or decisional parameters of transport systems (jourmard and gudmundsson, 2010). according to recent studies (jourmard and gudmundsson, 2010), the transport system has a number of 49 homogeneous chains of causality, which lead to the rise of various categories of environmental impact. the chains of causality and their hierarchy are shown in table 1. production of noise and vibrations accidents air pollution soil and water pollution impacts on land non-renewable resource use and waste handling greenhouse effect other impacts production of noise and vibrations the increase in noise levels triggers serious social and behavioral effects, such as discomfort and sleep disorders. effects on human health consist in hearing impairment, speech intelligibility, aggravation of physiological and psychological disorders, such as hypertension associated with exposure to high levels of noise or mental illness and reducing cognitive performance (jourmard and gudmundsson, 2010). the environmental indicators specific to noise chain of causality associated with the movement of vehicles (see fig. 1) can be divided into three main classes, namely: _ noise level indicators: are being used to describe the traffic noises according with their physical and energetic characteristics; chains of causality associated with the environmental impact of the transport system table 1 chains of causality associated with transport activities fig. 1 chain of causality associated with noise and vibrations from road traffic (jourmard and gudmundsson, 2010) journal of sustainable architecture and civil engineering 2016/1/14 22 _ noise exposure indicators: are being used to describe the noise effects on exposed individuals in terms of magnitude and territorial expansion; _ noise annoyance indicators: they characterize the discomfort experienced by those exposed to noise. accidents according with recent studies (world health organization, 2010), road accidents produce about 1.24 million fatalities per year, meaning 2.2% of total mortality in 2010. based on this assessment, a predominant increase of 2.4 million in fatalities by 2030 had been estimated, unless appropriate action is being taken. fig. 2 shows the corresponding chains of causality associated with road accidents. air pollution according fig. 3, the chains of causality associated with air pollution relates to odors produced as a consequence of so2 and volatile organic compounds emissions, particle contamination, decreased visibility, pollutants toxicity and photochemical pollution. soil and water pollution the chain of causality associated with soil and water pollution is broken down into three main categories, namely soil, surface water and groundwater, marine pollution and hydraulic changes (see fig. 4). fig. 2 chain of causality associated with accidents production (jourmard and gudmundsson, 2010) fig. 3 chain of causality associated with air pollution (jourmard and gudmundsson, 2010) 23 journal of sustainable architecture and civil engineering 2016/1/14 impacts on land according fig. 5, the impact of the transport system on the land refers to land take, habitat fragmentation, soil erosion and degradation and alteration of landscapes. in the case of habitat fragmentation, the main indicators describing this phenomenon are composition, shape and connectivity indicators of the inhabited area (rutledge, 2003). the indicators describing the basic characteristics of habitat fragmentation composition, are represented by the number and range of inhabited area. in the assessment of infrastructure projects, these indicators are being used to determine the minimum area of individual habitats. the shape indicators quantify the complexity of corresponding habitat areas. the areas could be homogeneous (with a circular shape) or a more complicated geometrical shape (didier and thompson, 2010). fig. 4 chain of causality associated with soil and water pollution (jourmard and gudmundsson, 2010) fig. 5 chain of causality associated with impact on land (jourmard and gudmundsson, 2010) journal of sustainable architecture and civil engineering 2016/1/14 24 the connectivity indicators measure the connectivity degree of inhabited area or isolation between areas. connectivity is a key element of the habitat structure and is defined by the extent to which some obstacles obstruct the movement of the species between different areas (tortorec, 2013). non-renewable resource and waste handling non-renewable resources are of particular interest in the transport, being used as well as energy sources (fossil fuels) and as construction materials. since the rate of their regeneration is very limited, it is essential to develop fuels and alternative energy sources and to recycle existing structures in order to limit existing current dependence on non-renewable materials (see fig. 6). greenhouse effect the most significant indicators describing the greenhouse effect are: global warming potential (gwp), global temperature change potential (gtp) and health indicator of greenhouse effect impact. gwp expresses the contribution of carbon dioxide (co2), methane (ch4), nitrous oxide (n2o), hydrofluorocarbons (hfcs), perfluorocarbons (pfcs) and sulfur hexafluoride (sf6) to global warming. further, the paper will present the influence of construction and maintenance processes and technologies specific with asphalt road pavements associated with the greenhouse effect chain of causality through a life cycle assessment analysis conducted according to the methodology incorporated into the aspect software, version 3.1. given the high levels of pollution nowadays and the fact that, according to european commission, transport is responsible for 32% of europe’s energy consumption and 28% of total co2 emissions, the development of sustainable road construction technologies and processes is more and more important. furthermore, besides the initial construction of a road pavement, the maintenance and rehabilitation strategies that will be applied represent a major factor in reducing the carbon footprint and, in the same time, in increasing the service life of the road. also, a significant role in decreasing polluting emissions is played by the moment of intervention. if an intervention strategy is applied at an optimum point in the road lifetime, the costs and the raw materials and energy consumption will be minimum and the service life of the road will be extended. otherwise, if the road is not rehabilitated when needed, the distresses progress exponentially, leading to the inability to use the road on full safety and comfort conditions. additionally, the rehabilitation investments, seen both in a financial perspective, as well as in terms of material consumption and labor required, will be directly correlated with the exacerbation of greenhouse effect. the paper presents the results of recent research undertaken for the quantitative assessment of co2 equivalent emissions and energy consumption related to the construction and maintenance of a flexible road pavement using a life cycle assessment analysis incorporated into the aspect software. aspect software methodology aspect software, version 3.1, developed by transport research laboratory trl uk, provides fig. 6 chain of causality associated with nonrenewable resource use and waste handling (jourmard and gudmundsson, 2010) methods 25 journal of sustainable architecture and civil engineering 2016/1/14 a methodology for calculating greenhouse gas emissions during the pavement life cycle produced by using bituminous materials on roads. the aspect software enables the assessment of co2e emissions based on information collected concerning materials, transport and mixture plant characteristics (trl, 2014). the software database contains the necessary formulas and emission factors for calculating co2e emissions associated with the production, laying and maintenance of bituminous layers by taking into consideration all the stages of materials and energy production and all the processes from raw material extraction, production, transport and use phase of the asphaltic mixture to the end of their life (cradle to gate), shown in fig. 7. the process for calculating the co2e emissions associated to bituminous road pavement consists of three main stages, namely: a. the introduction of raw materials used in the asphalt mixture (total annual energy consumption for the acquisition, broken down by type of fuel and operation); b. data introduction regarding the asphalt mixes plant characteristics (plant type, annual production, energy consumption and asphalt mix composition); c. data introduction regarding installation of bituminous mix and visualization of the results. the study based on environmental grounds of road infrastructure was performed through a life cycle assessment analysis. the case study deals specifically with road pavement intervention strategies carried out using various rehabilitation alternatives. the life cycle assessment analysis was conducted on the entire built section of 1000 ml long and 7.0 m wide using a cradle to grave option, presented in fig. 7. the global warming potential, expressed in terms of co2e emissions has been assessed using the aspect software, version 3.1. 1. raw material acquisition 2. raw material transport 3. raw material processing 4. processed material transport 5. road component production 6. material transport to site 7. installation 8. scheme specific works 9. maintenance 10. end of life the simple surface treatment this strategy is performed in a single layer and consists in spreading a uniform continuous coating of bituminous binder, followed by spreading a layer of natural aggregates. due to the application of this intervention strategy are emitted into the atmosphere 144.75 kg co2e/t, the total being equal with 42760.33 kg co2e. slurry seal cold thin bituminous layers (slurry seal) are made of asphalt-based emulsions and polymer modified bitumen and can be applied in one coat or two, being used to repair a road pavement by fig. 7 the life cycle stages of asphalt mixtures cradle to grave (trl, 2014) methods journal of sustainable architecture and civil engineering 2016/1/14 26 completely sealing the surface. the results of the quantitative assessment of greenhouse gas emissions associated to the execution of slurry seal are shown in table 2. no. life cycle stage kg co2e/t total kg co2e 1-3 material extraction and processing 43.89 6144.42 4 transport to plant 40.32 5645.08 5 asphalt production 49.96 6994.68 6 transport to site 9.10 1274.42 7 laying and compacting 4.70 658.00 8 project works 0.00 0.00 9 maintenance 0.00 0.00 10 reconstruction 16.70 2338.00 stages 1-7 (140 tons slurry seal) 164.8 23054.59 no. life cycle stage kg co2e/t total kg co2e 1-3 material extraction and processing 48.8 14809.89 4 transport to plant 34.81 10722.15 5 asphalt production 47.83 14731.27 6 transport to site 30.17 9292.62 7 laying and compacting 4.70 1447.60 8 project works 0.00 0.00 9 maintenance 0.00 0.00 10 reconstruction 16.70 5143.60 stages 1-7 (308 t mixture) 182.30 56147.13 heat planner and 1” ac heat planner and 1” ac” consist in heating the road pavement surface, milling to a certain depth of the layer and mixing the resulting material with bituminous emulsion, after which the obtained mixture is spread and compacted accordingly. greenhouse gas emissions related to this process are presented in table 4. thin overlays thin overlay ¾ inch is a means of maintenance and rehabilitation of existing road pavement by applying a thin layer of asphalt mixture. this process is used to repair damages like weathering and raveling, bleeding, minor cracks, etc. and is used to enhance the road surface characteristics and not the structural ones. table 3 presents the quantities of co2e associated with thin layers reinforcement. table 2 emissions associated with the execution of slurry seal table 3 co2e emissions associated with thin layers reinforcement (thin overlay ¾ inch) 27 journal of sustainable architecture and civil engineering 2016/1/14 reconstruction of a new road flexible pavement finally, taking into consideration the same assumptions defined above, the effect on the environment associated with road reconstruction has been measured and the final results of the impact assessment are given in table 5. fig. 8 shows the life cycle stages and the supply chain associated with the reconstruction of a new road pavement. in this respect, it has been selected a bituminous road pavement consisting in the following layers: _ wearing course (ba16, 4 cm – 644 tone); _ binder course (bad25, 6 cm – 945 tone); _ base course (ab2, 15 cm – 2258 tone); _ foundation layer (ballast, 20 cm); _ subgrade (20 cm). note: ba 16 – asphalt concrete with the maximum size of the aggregate of 16 mm bad 25 asphalt concrete with the maximum size of the aggregate of 25 mm ab – asphalt base no. life cycle stage kg co2e/t total kg co2e 1-3 material extraction and processing 54.28 21167.33 4 transport to plant 31.50 12284.36 5 asphalt production 1.00 389.75 6 transport to site 30.17 11766.63 7 laying and compacting 4.70 1833.00 8 project works 0.00 0.00 9 maintenance 0.00 0.00 10 reconstruction 16.70 6513.00 stages 1-7 (390 t mixture) 121.64 53954.07  foundation layer (ballast, 20 cm);  subgrade (20 cm). note: ba 16 – asphalt concrete with the maximum size of the aggregate of 16 mm bad 25 asphalt concrete with the maximum size of the aggregate of 25 mm ab – asphalt base fig. 8. consideration of the whole processing chain from cradle (resource extraction) to fabrication and layering the mix on the road site (andrei, et al., 2016) also, besides the construction of asphalt layers, it has been considered and the execution of surface dressing and retexturing in the frame of in-situ maintenance with an extension of service life of 4 and 6 years. table 5. co2e emissions associated with the construction of a new road pavement no. life cycle stage kg co2e/t total kg co2e 1-3 material extraction and processing 52.88 203434.62 4 transport to plant 36.52 140500.34 5 asphalt production 47.83 83997.39 6 transport to site 6.48 24946.30 7 laying and compacting 4.70 18080.90 8 project works 241.23 36184.10 9 maintenance 34.27 5140.00 10 reconstruction 15.89 61120.78 stages 1-7 (3997 t material) 148.42 637220.33 the co2e emissions from the construction, maintenance and rehabilitation of road flexible pavements depend largely on how the required materials are extracted and processed, only the production of aggregates and asphalt being responsible for 1.2 million tons of co2 and consumption 705000 mwh in electricity and 43000000 mwh in 2009, broken down as shown in fig. 9 (banes and fifer, 2011). table 4 co2e emissions associated with heat planner and 1” ac fig. 8 consideration of the whole processing chain from cradle (resource extraction) to fabrication and layering the mix on the road site (andrei, et al., 2016) journal of sustainable architecture and civil engineering 2016/1/14 28 also, besides the construction of asphalt layers, it has been considered and the execution of surface dressing and retexturing in the frame of in-situ maintenance with an extension of service life of 4 and 6 years. no. life cycle stage kg co2e/t total kg co2e 1-3 material extraction and processing 52.88 203434.62 4 transport to plant 36.52 140500.34 5 asphalt production 47.83 83997.39 6 transport to site 6.48 24946.30 7 laying and compacting 4.70 18080.90 8 project works 241.23 36184.10 9 maintenance 34.27 5140.00 10 reconstruction 15.89 61120.78 stages 1-7 (3997 t material) 148.42 637220.33 the co2e emissions from the construction, maintenance and rehabilitation of road flexible pavements depend largely on how the required materials are extracted and processed, only the production of aggregates and asphalt being responsible for 1.2 million tons of co2 and consumption 705000 mwh in electricity and 43000000 mwh in 2009, broken down as shown in fig. 9 (banes and fifer, 2011). 31% 12% 56% 1% energy consumption associated to various materials crushed rock sand and gravel asphalt cement however, these amounts may decrease considerably if the aggregates excess water is reduced as the highest proportion of energy is consumed for drying and heating the aggregates. another way the improvement the manufacturing process involves the use of recycled asphalt mixtures, resulting in reductions of up to 50% of emissions (andrei, et al., 2014). analyzing the results research, performing a simple surface treatment implies the release into the atmosphere of an amount equal to 42760.33 kg co2e, its total cost being $ 3367 lane/mile and the service life increasing by 3.7 years. the execution of thin layers leads to 56147.13 kg co2e, about 24% more than the previous strategy, but with an extension of 5.8 years. execution costs are also higher than the simply surface treatment by about 65%. table 5 co2e emissions associated with the construction of a new road pavement fig. 9 segmentation of energy consumption by main categories of aggregate (banes and fifer, 2011) 29 journal of sustainable architecture and civil engineering 2016/1/14 execution of slurry seal have as environmental impact the production of 23054.59 kg co2e (59% lower than for simple treatment and by 46% compared with thin layers). it extends the service life by 3.7 years, while the costs are $ 6398/lane/mile. the highest increase in service life corresponds to heat planner and adding a 2.5 cm thickness layer, which represents 6.9 years. nevertheless, associated costs and pollutant emissions are higher than in the first case ($ 8081/lane/mile and 53954.07 kg co2e). in the case of construction of a new road pavement, in addition to the construction process of asphalt layers, it has been considered also the execution of surface dressing and retexturing in the frame of in-situ maintenance. results of recent research undertaken have emphasized the need to apply intervention strategies at the appropriate time in order to prolong the road service life, because the alternative of constructing a new road pavement implies consumption of huge quantities of bituminous binders and non-renewable granular material simultaneously with the discharge into the atmosphere of an amount of 637220.33 kg co2e. the chains of causality associated to transport system assist in identify, monitor and assess all the environmental problems arising from the development of road networks. these chains can be a relevant instrument in decision making process and for comparative analysis of transport policies or technologies in order to select the optimal solution related to road projects, taking into account the urgent environmental aspects. the undertaken research also focused greatly on emphasizing environmental indicators specific to the analyzed chains of causality necessary in road field technique for quantifying and evaluating sustainability for current and future trends in the global concept of sustainable development. given that the most pressing environmental issue facing mankind consist in the effect of global warming and climate change associated with this phenomenon due to the increase concentration of pollutants in the atmosphere, the paper presents the results of recent research undertaken for the assessment of the environmental indicators associated with the construction of an asphalt road pavement, based on a cradle to grave approach, which includes all the stages of materials and energy production and all processes from raw material extraction, production, transportation and use phase of the products to their end of life. the life cycle assessment analysis was conducted on the entire built section of 1000 ml long and 7.0 m wide using a cradle to grave option, incorporated in the aspect software. within this study five different intervention strategies performed for regular maintenance and structural reinforcement of a road flexible pavement have been analyzed in an environmental perspective as well as in an engineering approach. regarding the ecological impact associated with road works the most ecofriendly strategy is represented by the execution of slurry seal, which will also extend the service life of the pavement with 3.7 years. looking at the results under an engineering consideration, the optimal rehabilitation strategy to be applied consists in heat planner and adding a 2.5 cm thickness layer, the service life extension being in this case equal with 6.9 years, thus having a structural contribution. the worst case scenario studied in the frame of this research is represented by the reconstruction of a new pavement, when the specific intervention strategies haven’t been applied when needed and the pavement condition of the road is poor, the user’s safety being endangered. in this case the only viable solution is rebuilding the pavement, the ecological impact being significantly higher. additionally, to reduce the environmental impact of road infrastructure, a great importance is represented by the humidity of component materials, as the largest amount of energy is consumed in drying and heating of aggregates. according to recent studies, another way to streamline the manufacturing process implies the use of recycled asphalt mixtures, resulting in reductions of up to 50% the emissions. discussions journal of sustainable architecture and civil engineering 2016/1/14 30 andrei, r., lucaci, g., boboc, v., nicuţă, a. m., condurat, m., botezatu, i. and dragoslav (dima), d. n. supply chains for the construction of recycled asphalt pavement for roads and streets in iasi county of romania. in j. r. calzada, i. kaltenegger, j. patterson and f. varriale (eds.), cost action tu1104 smart energy regions skills, knowledge, training and supply chains (pp. 219-226). isbn: 978-1-899895-21-2, cardiff: the welsh school of architecture, cardiff university, u.k., 2016. andrei, r., nicuţă, a. m., ţăranu, n. and lucaci, g. reducerea emisiilor poluante pe durata de viaţă a îmbrăcăminţilor asfaltice de drumuri [the reduction of pollutant emissions during the life cycle of asphalt road pavements], revista “drumuri poduri” [journal “roads bridges”], editorial nr. 199, 2014. banes, r. and fifer, j. aggregate energy consumption guide summary report. carbon trust, 2011. didier, k. and thompson, j. habitat fragmentation and connectivity. cbd technical series no. 32, 2010. retrieved 08 18, 2014, from the convention on biological diversity: http://www.cbd.int/ts32/ts32chap-10.shtml#frag_met eea. glossary. european environment agency, 2009. iso 14040, life cycle assessment principles and framework, 2006. references jourmard, r. and gudmundsson, h. indicators of environmental sustainability in transport, an interdisciplinary approach to methods. institute national de recherche sur les transports et leur securite – inrets, 2010. rutledge, d. landscape indices as measures of the effect on fragmentation: can pettern reflect process? new zealand intelligence a modern approach (second edition ed.). prentice hall, 2003. tortorec, l. e. reproductive success responses to habitat fragmentation in eurasian treecreepers, 2013. retrieved 08 01, 2014, from sarja ser. aii osa tom. 281, turun yliopisto university of turku: https://www.doria.fi/bitstream/handle/10024/9025 trl. aspect software user manual version 3.1. transport research laboratory. transport research laboratories, 2016. trl. asphalt pavement embodied carbon tool. transport research laboratory, 2014. retrieved 04 10, 2014, from http://www.sustainabilityofhighways.org.uk world health organization. global health observatory (gho) data, 2010. retrieved 03 23, 2015, from number of road traffic deaths: http://www.who.int/ gho/road_safety/mortality/traffic_deaths_number/en/ condurat mihaela phd student technical university „gh. asachi” from iasi, romania, faculty of civil engineering and building services, department of transportation infrastructure and foundations main research area impact assessment of road transport system. measures regarding the prevention and reduction of ecological impact associated with road transport infrastructure address bulevardul profesor dimitrie mangeron 1, iași 700050 tel. +40 745 409 930 e-mail: conduratmihaela@yahoo.com about the authors 61 journal of sustainable architecture and civil engineering 2016/3/16 *corresponding author: res.ka@frederick.ac.cy sustainability tools for the assessment of construction materials and buildings received 2016/08/31 accepted after revision 2016/10/27 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 61-69 doi 10.5755/j01.sace.16.3.16172 © kaunas university of technology sustainability tools for the assessment of construction materials and buildings jsace 3/16 http://dx.doi.org/10.5755/j01.sace.16.3.16172 angeliki kylili*, paris a. fokaides frederick university, cyprus, school of engineering, 7, frederickou str., 1036, nicosia, cyprus lina seduikyte kaunas university of technology, faculty of civil engineering and architecture studentu g. 48, kaunas, lithuania introduction the construction industry, contributing to about 9% of the european union’s gdp, has played a significant influential role in the development of the energy strategy of europe and is also anticipated to be an important contributor in its successful implementation (ec, 2016). holistic sustainability assessment tools that are able to evaluate and optimise the environmental performance of construction materials and buildings are considered a key for the development of advanced building designs and use of sustainable building materials and elements and green energyefficient systems that will raise high the sustainability level of the european built environment. the aim of this work is the thorough explanation of the standardised lca methodology, and the introduction of the approach of ecohestia, a comprehensive building sustainability assessment tool. in view of that, the current legislation addressing the construction industry, as well as the state-of-theart life cycle assessment (lca) tools that are used for the sustainability assessment and optimisation of construction materials and buildings are also presented. furthermore, through the employment of ecohestia, the environmental impact of a case study building is defined, also providing a detailed breakdown of the contribution of each construction material in the overall environmental performance of the building. the analysis of the results has not only determined on the construction materials of the building that are most harmful to the natural resources and the environment, but also showcased the effectiveness and added value of utilizing this approach in moving forward towards a more sustainable green building sector. keywords: building material, ecohestia, environmental performance, lca, sustainability tool. with almost half of the energy and material consumption and a third of the waste generation and water consumption of the total european union’s figures, buildings are having a great weight on the energy strategy of europe (com(2007)860; com(2011)571). legislation is motivating research communities worldwide to develop more efficient and more transparent methodologies and tools for assessing the sustainability of buildings as a whole, as well as all the sustainability of the elements that make up a building. and there is a common consensus, among politicians, scientists and industry experts, which establishes life cycle assessment (lca) as the best framework for evaluating the performance of buildings and construction products currently available (recommendation 2013/179/eu; bernstein and mandyyck, 2013). the sustainability performance of any journal of sustainable architecture and civil engineering 2016/3/16 62 construction product or building is the sum of the energy and environmental benefits gained and energy consumption and environmental deterioration arising from the extraction of the raw materials, the manufacturing of the product or the construction of the building, the operation and maintenance phase, and the selected waste management route. taking into consideration the impact from all of the phases of the investigated object’s life cycle, it can be stated that decisionmaking is not anymore a point of perception or opinion, but is ought to be based on reliable and transparent evidence. standardisation of the lca methodology for having common grounds for measuring and communicating the life cycle environmental performance of products or systems has been established a decade ago (iso 14040:2006), and it seems to make headway at a rapid pace. motivation for the development of sustainability tools legislation developed specifically for construction materials aspires the elimination of technical barriers that limit their trading within the market. the construction products regulation establishes harmonised technical specifications on the assessment of the performance of construction products and on the use of ce marking on them (regulation no 305/2011). yet, a large part of the equation for the achievement of a nearly zero energy european building stock (energy performance of buildings directive (epbd) 2010/31) and an energy efficient europe (energy efficiency directive 2012/27/ec) is the development and use of sustainable materials, green technologies and energy-efficient systems in both new and refurbished buildings. references to construction products are also indicated in the ecodesign directive (directive 2009/125/ec), establishing a framework where the design of a number of energyrelated products, also referring to construction such as windows, insulation materials, should be optimized for minimum environmental deterioration and maximum cost savings. several additional european initiatives are found aligned and complement the existing policies with reference to the construction sector on resource efficiency and sustainability aspects. the key objective of the roadmap to a resource efficient europe (com(2011)571) is to actively involve achieve the whole value chain of the sector in order to achieve significant improvements in the energy, material, and water consumption. the initiative also envisions the transformation of the building stock through the use of life cycle approaches for the development of advanced building designs, incorporation of improved sustainable construction materials and elements and sustainable reuse/ recycling of construction demolition waste (cdw). aligned with the resource efficient europe goal is the strategy for the sustainable competitiveness of the construction sector and its enterprises, where the union recognises the level of significance of construction smes on adopting resource efficient building methodologies and practices for tackling societal challenges and boosting the european construction sector globally (com(2012) 433). the european initiative on resource efficiency opportunities in the building sector (com(2014)445) highlights the importance of reducing the environmental burden of buildings throughout all the stages of its lifetime. the communication promotes, among others, the more resource efficient manufacturing of construction materials through the reuse of existing materials, the incorporation of recycled materials and the use of waste as fuel. state-of-the-art sustainability tools the collaboration between the construction industry and the relevant research community has led to the development of state-of-the-art sustainability assessment tools that are able to evaluate the life cycle environmental impact of building materials and buildings. a total of nineteen building environmental assessment tools, the majority of which are coming from european countries, have been reported to deploy lca for their evaluation methodology (castellano et al., 2014). popular examples include the green guide of the building research establishment environmental assessment method (breeam) (uk), athena (canada), eco quantum (netherlands), ecoeffect (sweden), envest (uk), and comprehensive assessment system for built environment efficiency (casbee) (japan). the green guide is part of the breeam, an accredited environmental rating 63 journal of sustainable architecture and civil engineering 2016/3/16 scheme for buildings, and contains more than 1500 specifications used in a variety of types of building. the underlying lca methodology enables the rating of the environmental performance of buildings by separating the parts of buildings into elemental categories (bre, 2015). the athena sustainable materials institute has developed two lca tools; the athena impact estimator for buildings and the athena ecocalculator for assemblies, where the latter allows for a more detailed and accurate assessment of the buildings’ environmental impact. their databases provide cradle-to-grave information for building materials and products, transportation, construction, as well as demolition processes (athena sustainable materials institute, 2016). it is also worth mentioning that one of the most popular sustainable building certification programs, leadership in energy and environmental design (leed) (usa), has also incorporated lca in its latest released rating system (usgbc, 2016). the most common cited lca software tools in the construction industry, also employed for the majority of the forth mentioned state-of-the-art sustainability assessment tools include gabi and simapro. the two represent the most wellestablished product sustainability solutions for lca with over 25 years of experience and collaboration with leading lca professionals and industry experts. additionally, the reliability of results of both tools is further enhanced through the incorporation of the world’s most consistent and transparent life cycle inventory (lci) database, ecoinvent. however, regional legislation in combination with globalization has made the sharing of best practices and expertise much easier than ever. however, types of information or data that might be applicable for one country may not be suitable for another. accordingly, there is the necessity for the introduction of a common framework for implementing lca studies on assessing the sustainability of building materials, but at the same time in-depth development and understanding of specific country and local data is also needed on the subject (world green building council, 2013; kylili and fokaides; 2016). life cycle assessment (lca) methodology the international standard on lca is providing the methodology on implementing lca for the evaluation and interpretation of the potential life cycle environmental impacts arising as a result of a product or system (iso 14040:2006). the transparency of the methodology is attributed to a four stage path; including the goal and scope definition, the inventory analysis, the impact assessment and the interpretation of the results stages. the goal and scope definition phase defines the object under investigation for the conduction of the lca study, including its key objectives. in this phase, the functional unit, the system boundaries, the data requirements, the limitations and assumptions to be considered in the study are also presented in detail. next is the lci phase, which represents the data collection share of the study. the deliverable of the lci phase is a list of all inputs and outputs, including raw materials, energy, and emissions and other waste released into the natural environment, in relation to the system under investigation throughout its whole life cycle. the life cycle impact assessment (lcia) phase evaluates all inputs and outputs, as defined in the previous stage, into potential environmental impact into selected environmental impact categories. the list of environmental impact categories varies according to the evaluation method followed, however all lcia methods should cover all certain impact categories according to the international reference life cycle data system (ilcd) handbook (wolf et al., 2012). the ilcd handbook was developed and established by the institute for environment and sustainability in the european commission joint research centre (jrc) and the environment dg through a series of public and stakeholder consultations (jrc, 2014). lcia results can support the definition of the main contributors of environmental benefits or deterioration at the selected impact categories that can be further exploited for the improvement/ optimisation of the system’s under investigation environmental performance. the final interpretation of the results phase engages with the reporting of the findings and recommendations in relation to the initial objectives of the lca study. methods journal of sustainable architecture and civil engineering 2016/3/16 64 ecohestia building sustainability assessment tool ecohestia is a comprehensive environmental impact lca tool that integrates the most commonlyused building elements for cyprus (serg, 2016). ecohestia performs ‘cradletogate’ lca of buildings based on inventory data of construction materials and building elements. this data is in fact based on the characteristics of cyprus and primary sources from the local construction industry. personal communications with local construction materials manufacturers have established the required amounts of raw materials and energy for the manufacturing of the final products. the fuels required for electricity generation, as well as transportation are also representative of the country’s facts. transportation distances have been calculated using map applications, while average emission factors for cyprus’ energy generation and transportation have been also been extracted from validated databases (gabi database). the analysis of ecohestia is according to the principles described in the iso 14040 standard and employs the gabi software and cml 2001 methodology. accordingly, ecohestia’s lcia generates the potential impact of the building, on the following environmental impact categories: fig. 1 the approach adopted by ecohestia, a comprehensive building sustainability assessment tool _ global warming potential (gwp 100 years) in [kg co2-equiv.] _ acidification potential (ap) in [kg so2-equiv.] _ eutrophication potential (ep) in [kg phosphate-equiv.] _ ozone layer depletion potential (odp, steady state) in [kg r11-equiv.] _ abiotic depletion potential of elements (adp elements) in [kg sb-equiv. _ abiotic depletion potential of fossils (adp fossils) in [mj] _ freshwater aquatic ecotoxicity potential (faetp) in [kg dcb-equiv.] _ human toxicity potential (htp) in [kg dcb-equiv.] _ marine aquatic ecotoxicity potential (maetp) in [kg dcb-equiv.] _ photochemical ozone creation potential (pocp) in [kg etheneequiv.] _ terrestric ecotoxicity potential (tetp) in [kg dcb-equiv.] 65 journal of sustainable architecture and civil engineering 2016/3/16 additionally, ecohestia also generates the building’s carbon footprint (cf) in carbon dioxide equivalent (co2equiv.) and nonrenewable embodied energy (nre) in megajoules (mj). the approach employed by the building sustainability assessment tool is straightforward and friendly towards its users. quantity data for each construction material incorporated into the building under investigation is extracted from its bill of quantities (boq). this data is used as an input in the ecohestia tool. for the generation of the lcia results, this data are evaluated against the key performance indicators (kpis) of the tool (fig. 1). the ecohestia kpis represent the environmental impact of each construction material per kilogram (kg) of material, considering all the raw materials and energy requirements for its manufacturing at the plant and its transportation to the construction site. the final lcia results are provided per construction material. case study building ecohestia has been used for the implementation of the lca of a levelground, twostorey residential building located in nicosia, cyprus. the building’s total useful floor area, including covered and uncovered areas, is 315 m2, while its total height is 11.5 m. the construction of the case study building is typical of the country’s building stock. with reference to the building’s boq, the masonry incorporates concrete, brickwork, and plasterboards. expanded polystyrene was incorporated into the building envelope for insulation purposes, plasterboard used as a roof in all floors, and the building’s doors and windows are made of aluminium. the ecohestia generated results for the case study building per construction material are presented in table 1. the table indicates the lifecycle impact potential of each of the building’s materials for the selected impact categories. for comparison purposes, the results are also illustrated in methods table 1 summary of bill of quantities (boq) of case study building a/a construction material quantity unit a concrete works c20/25 391200 kg c30/37 530400 kg b steel 51000 kg c brickwork thermal brick 30cm 17222 kg thermal brick 25cm 24605 kg thermal brick 20cm 46683 kg d plasterboard 1456 kg f insulation materials eps 340,5 kg g plaster 5760 kg h interior paint 86,1 kg i exterior paint 65,475 kg j aluminium 25760 kg k glass 2300 kg l pvc 12,9 kg terms of the percentage contribution of each construction material in the overall environmental impact in fig. 2. it is evident that concrete, c20/c25 and c30/c37, are the greatest contributors across the majority of the impact categories. this is attributed to both the energyconsuming process of cement manufacturing and associated high carbon emissions, as well as the large quantities of materials that were required for the construction of the building (pelisser et al., 2012; chrysostomou et al., 2015; teixeira et al., 2016; vieira et al., 2016). in fact, the share of contribution of c30/c37 ranges between 42% and 46% except the odp category which is 7%. similarly, c20/c25 contribution ranges between 24% and 31% and only 1.6% in the odp category. aluminium and steel also heavily burden the environmental impact of the building, as a result of their high non renewable energy consumption for their manufacturing (ecohestia database). journal of sustainable architecture and civil engineering 2016/3/16 66 aluminium has the highest contribution in the odp category, 88% of the total in particular, arising mainly from the alumina processing phase. the specific material that is used for the building’s doors and windows has also the second highest in adp category after c30/ c37. its share for the rest of the categories is approximately 12% of the total impacts. steel used for reinforcement, on the other hand is indicating a strong weight (10%) for the abiotic depletion of fossils. regardless of their low embodied energy and carbon footprint, when summed brickwork is attributed approximately the 4.5% of the overall environmental impact across all categories, except the odp and adp elements categories, where their share is insignificant. in fact, the most environmentally-destructive processes in brick manufacturing are mainly their final phase during table 2 ecohestia life cycle impact assessment (lcia) results per construction material for case study building a /a c o nst ru ct io n m at er ia l q u an ti ty u ni t g w p a p e p o d p a d p e le m en ts a d p fo ss ils fa e t p h tp m a e tp p o c p te tp c f n r e a concrete works c20/25 163 m3 5,0 e+05 4,13 e+03 1,51 e+02 2,38 e-07 9,42 e-02 6,24 e+06 4,61 e+03 5,17 e+04 2,34 e+07 2,12 e+02 1,15 e+03 4,9 3e+05 6,69 e+06 c30/37 221 m3 7,18 e+05 6,03 e+03 2,21 e+02 1,04 e-06 1,63 e-01 9,12 e+06 6,74 e+03 7,58 e+04 3,45 e+07 3,15 e+02 1,71 e+03 7,00 e+05 9,81 e+06 b steel 51000 kg 1,36 e+05 7,97 e+02 4,49 e+01 2,03 e-07 7,94 e-03 2,30 e+06 6,87 e+02 9,93 e+03 6,10 e+06 4,62 e+01 1,92 e+02 1,30 e+05 2,43 e+06 c brickwork thermal brick 30cm 109 m2 1,37 e+04 1,15 e+02 4,23 e+00 1,69 e-08 6,82 e-04 1,74 e+05 1,29 e+02 1,44 e+03 6,54 e+05 5,96 e+00 3,29 e+01 1,33 e+04 1,88 e+05 thermal brick 25cm 133 m2 1,95 e+04 1,64 e+02 6,04 e+00 2,41 e-08 9,74 e-04 2,49 e+05 1,84 e+02 2,06 e+03 9,34 e+05 8,52 e+00 4,70 e+01 1,90 e+04 2,68 e+05 thermal brick 20cm 171 m2 3,70 e+04 3,11 e+02 1,15 e+01 4,57 e-08 1,85 e-03 4,71 e+05 3,49 e+02 3,91 e+03 1,77 e+06 1,62 e+01 8,92 e+01 3,61 e+04 5,09 e+05 d plasterboard 208 m2 2,20 e+04 1,42 e+02 6,53 e+00 1,76 e-08 1,37 e-03 2,52 e+05 1,20 e+02 1,86 e+03 1,22 e+06 7,68 e+00 3,59 e+01 2,10 e+04 2,68 e+05 f insulation materials eps 227 m2 8,36 e+02 2,10 e+00 1,87 e-01 5,21 e-08 2,32 e-04 2,60 e+04 7,33 e+00 4,04 e+01 2,60 e+04 3,00 e-01 5,03 e-01 7,63 e+02 2,87 e+04 g plaster 1920 m2 2,13 e+03 1,21 e+01 5,44 e-01 6,78 e-09 1,50 e-03 2,02 e+04 1,36 e+01 1,51 e+02 7,42 e+04 5,27 e-01 5,76 e+00 2,09 e+03 2,19 e+04 h interior paint 615 m2 3,44 e+01 1,37 e-01 1,38 e-02 5,66 e-09 1,11 e-05 1,07 e+03 3,18 e-01 2,02 e+00 1,78 e+03 2,42 e-02 2,90 e-02 3,12 e+01 1,21 e+03 i exterior paint 485 m2 4,41 e+01 1,74 e-01 1,81 e-02 7,57 e-09 1,35 e-05 1,43 e+03 4,20 e-01 2,57 e+00 2,20 e+03 3,23 e-02 3,35 e-02 3,99 e+01 1,62 e+03 j aluminium 92 m2 2,07 e+05 1,67 e+03 6,31 e+01 1,31 e-05 9,93 e-02 2,59 e+06 1,84 e+03 2,11 e+04 1,02 e+07 8,97 e+01 4,80 e+02 2,01 e+05 2,83 e+06 k glass 54 m2 5,33 e+03 4,21 e+01 2,05 e+00 3,60 e-08 1,33 e-02 6,74 e+04 4,41 e+01 4,94 e+02 2,37 e+05 2,33 e+00 1,15 e+01 5,18 e+03 7,29 e+04 l pvc 87 m2 6,82 e+01 4,61 e-01 2,05 e-02 1,56 e-10 9,46 e-05 7,90 e+02 4,26 e-01 5,95 e+00 3,60 e+03 2,52 e-02 1,21 e-01 6,55 e+01 8,45 e+02 total 1,67 e+06 1,34 e+04 5,11 e+02 1,48 e-05 3,85 e-01 2,15 e+07 1,47 e+04 1,68 e+05 7,91 e+07 7,05 e+02 3,59 e+03 1,62 e+06 2,31 e+07 67 journal of sustainable architecture and civil engineering 2016/3/16 fig. 2 percentage contribution of construction materials in the overall performance of the case study building in selected environmental impacts which brick are dried and fired, and the crushing and milling stage of the raw materials (ecohestia database). notable is also the contribution of plasterboard, which accounts to around 1% to the majority of the selected categories, considering its small quantities used for the building’s construction. its low environmental performance is mainly the result of the calcine system, as well as the crushing and grinding preceding this stage. similarly despite the relatively high embodied energy and carbon footprint of polyvinyl chloride (pvc), its share of impact on the overall building’s environmental performance is minor due to the low quantities of installation. negligible is also the contribution of the exterior and interior paint in the overall impact of the case study building. the existing energy policies and legislation are calling the construction industry for advanced building designs, use of sustainable building materials, green technologies and energy-efficient systems, and increased reuse and recycling rates of waste for improved energy efficiency and reduced energy consumption. the realization of these key goals is facilitated through the employment of holistic sustainability assessment tools that are able to evaluate and optimise the environmental performance of construction materials and buildings. often enough, the coupling of these methodologies with design tools allow the optimisation even at an early design phase of new buildings or existing building that are planned to undergo renovation (kylili et al., 2015). the effectiveness and added value of employing a lca sustainability assessment tool has been presented in this work. ecohestia, a comprehensive building environmental assessment tool for the case of cyprus, has illustrated its potential in providing in detail the environmental contribution of each construction material in the overall environmental performance of the building. the lcia results have indicated that concrete is the most environmentally destructive material in the construction, accounting for at least the 66% of the building’s overall environmental impact, with an exception of the ozone depletion impact. steel used for reinforcement and aluminium for doors and windows have also been shown to carry a significant share of the overall performance, and in particular in the abiotic depletion of fossils potential and the ozone depletion potential, respectively. by providing a breakdown of the construction materials’ environmental impact, ecohestia can assists the construction industry as well as the relevant scientific community in deciding which conclusions journal of sustainable architecture and civil engineering 2016/3/16 68 route to follow and what should be the focus towards the greening of the built environment. it is a decisionmaking tool, which provides answers in the questions surrounding the improvement of the sustainability level of the building sector with reliable and transparent evidence. ecohestia also promotes the in-depth development and employment of countryspecific and local data for the implementation of lca studies for the construction sector and beyond. athena sustainable materials institute (2016). home. retrieved august 26, 2016, from http:// www.athenasmi.org/ bernstein, h., & mandyyck, j. (2013). world green building trends smartmarket report. prepared for mcgraw-hill construction and united technologies climate, controls & security. bre (building research establishment) (2015). green guide to specification. retrieved august 26, 2016, from http://www.bre.co.uk/greenguide/ castellano, j., castellano, d., ribera, a., & ciurana, j. (2014). development of a scale of building construction systems according to co 2 emissions in the use stage of their life cycle. building and environment, 82, 618-627. https:/doi.org/10.1016/j.buildenv.2014.09.016 chrysostomou, c., kylili, a., nicolaides, d., & fokaides, p. a. (2015). life cycle assessment of concrete manufacturing in small isolated states: the case of cyprus. international journal of sustainable energy, 1-15. https:/doi.org/10.1080/14786451.2015.1100197 cml, 2001. cml’s impact assessment methods and characterisation factors. leiden university, institute of environmental science (cml). ec–european commission. (2007). communication on a lead market initiative for europe. com(2007)860. ec–european commission. (2010). directive on the energy performance of buildings. directive 2010/31/ec. ec–european commission. (2011). communication on roadmap to a resource efficient europe. com (2011), 571. ec–european commission. (2012). communication on strategy for the sustainable competitiveness of the construction sector and its enterprises. com(2012), 433. ec–european commission. (2012). directive on energy efficiency. directive 2012/27/ec. ec–european commission. (2012). directive on establishing a framework for the setting of ecodesign requirements for energy-related products. directive 2009/125/ec. ec-european commission. (2013). commission recommendation of 9 april 2013 on the use of common methods to measure and communicate the life cycle environmental performance of products and organisations. annex ii: product environmental footprint (pef) guide. european commission. ec-european commission. (2014). communication on resource efficiency opportunities in the building sector. com(2014)445. ec-european commission. (2016). ec’ website. construction. retrieved 27 october 2016. available from: https://ec.europa.eu/growth/sectors/construction_en gabi. 2016. software-system and databases for life cycle engineering. version 6. stuttgart, echterdignen: pe international. iso, i. (2006). 14040: environmental management– life cycle assessment–principles and framework. london: british standards institution. joint research centre (jrc) – european commission (ec). (2014). jrc’s website. european platform on life cycle assessment. retrieved 27 october 2016. available from: http://eplca.jrc.ec.europa.eu/ kylili, a., & fokaides, p. a. (2016). life cycle assessment (lca) of phase change materials (pcms) for building applications: a review. journal of building engineering, 6, 133-143. https:/doi.org/10.1016/j.jobe.2016.02.008 kylili, a., fokaides, p. a., vaiciunas, j., & seduikyte, l. (2015). integration of building information modelling (bim) and life cycle assessment (lca) for sustainable constructions. journal of sustainable architecture and civil engineering, 13(4), 28-38. no, e. r. (2011). 305/2011 of the european parliament and of the council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106. eec. pelisser, f., barcelos, a., santos, d., peterson, m., & bernardin, a. m. (2012). lightweight concrete production with low portland cement consumption. journal of cleaner production, 23(1), 68-74. https:/doi.org/10.1016/j.jclepro.2011.10.010 references 69 journal of sustainable architecture and civil engineering 2016/3/16 teixeira, e. r., mateus, r., camões, a. f., bragança, l., & branco, f. g. (2016). comparative environmental life-cycle analysis of concretes using biomass and coal fly ashes as partial cement replacement material. journal of cleaner production, 112, 2221-2230. https:/doi.org/10.1016/j.jclepro.2015.09.124 usgbc (us green building council). (2016). leed. retrieved august 26, 2016, from http://www.usgbc. org/ vieira, d. r., calmon, j. l., & coelho, f. z. (2016). life cycle assessment (lca) applied to the manufacturing of common and ecological concrete: a review. construction and building materials, 124, 656-666. https:/doi.org/10.1016/j.conbuildmat.2016.07.125 wolf, m. a., pant, r., chomkhamsri, k., sala, s., & pennington, d. (2012). the international reference life cycle data system (ilcd) handbook-jrc reference reports. world green building council. (2013). the business case for green building: a review of the costs and benefits for developers, investors, and occupants. angeliki kylili research associate frederick research center and frederick university, cyprus, school of engineering main research area energy efficiency of buildings, sustainable energy resources, lca address 7, frederickou str., 1036, nicosia, cyprus tel.: +35722394394 e-mail: res.ka@frederick.ac.cy paris a. fokaides dr. lecturer frederick university, cyprus, school of engineering main research area computational and experimental building physics, sustainable energy technologies, renewable energy sources address 7, frederickou str., 1036, nicosia, cyprus tel.: +35722394394 e-mail: eng.fp@frederick.ac.cy lina seduikyte assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area indoor environment, lca, energy efficiency of buildings address studentu st. 48, lt-44403, kaunas, lithuania tel.: +370 37 350453 e-mail: lina.seduikyte@ktu.lt about the authors journal of sustainable architecture and civil engineering 2018/2/23 16 corresponding author: jcardoso@ubi.pt haussmann structural floors repairs and strengthening techniques received 2018/08/17 accepted after revision 2018/09/26 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 16-24 doi 10.5755/j01.sace.23.2.21426 haussmann structural floors repairs and strengthening techniques jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.21426 rui cardoso c-made, civil engineering and architecture department, beira interior university 6201-001 covilhã, portugal introduction haussmann buildings architecture spread throughout the city of paris. those buildings were constructed in the 19th century, being now centenarians. however, they present several pathologies which prevent their adequate use, moreover, an update regarding users security, sound, thermal and fire requirements is, among others, urgently needed. additionally, there is actually, in paris, an increasing demand for hotel rooms. for those previous reasons, haussmann buildings are nowadays submitted to heavy operations related to use change, conservation, and rehabilitation. in this paper, repair and strengthening techniques used in old timber and metallic floors and retaining a great amount of the original structure are introduced. this presentation is the result of a technical survey realized during a heavy rehabilitation operation which takes place between 2015 and 2017 in a haussmann building complex located at la madeleine. the knowledge from this study could be very useful for the development of sustainable rehabilitation and strengthening techniques, aiming to preserve this important building heritage or similar ones existing in other countries. keywords: floor rehabilitation, haussmann buildings, strengthening, structural characterization. a huge quantity of rehabilitation and strengthening works are being realized actually in paris haussmann buildings. in fact, those buildings being old, since built or rebuilt around the 19th century, present nowadays a very poor state of conservation and several pathologies affect their main structure. furthermore, the environmental issue related to energy consumption for cooling and heating make them obsolete. beyond that, the haussmann buildings are representative of the paris architecture, (jombert c.a., 1764), (froidevaux y., 1986), (lepoutre d., 2010), (jordan d.p., 2015) since all the city is based on that architecture, which was used until the introduction of concrete and steel in the 20th century. it is of vital importance to preserve and protect this legacy and demolition can´t be a solution. furthermore, there is a huge demand for hotel rooms in the city of paris due to a growing tourism activity. all the reasons present previously justify the urgent need to realize rehabilitation and strengthening works. this scenario related to traditional building heritage state of conservation is not unique and can be found in several european countries, (branco j. et al., 2006), (catarig al. and kopenetz l., 2007), (cardoso r. et al., 2015, 2016, 2017). this article characterizes the strengthening techniques applied to the floors of a haussmann building complex located at la madeleine, based on information gathered during the rehabilitation works that were performed between 2015 and 2017. this complex is located at la madeleine near the saint marie madeleine church. fig 1-a) shows an aerial view of the complex implantation and fig 1-b) shows a front view of the existing facade. 17 journal of sustainable architecture and civil engineering 2018/2/23 the haussmann floors this article is original because the technical observations were made during the rehabilitation working stage, by the author, which was simultaneously the strengthening project designer. proper investigations were realized in the existing superstructure, on the foundations and particularly in the floors structural elements, before and after strengthening. complementary, an assessment of the geometric characteristics of the structural floor elements was realized. resulting in a step description of the floors strengthening technique used. we strongly believe this paper will allow to better understand the actual floor strengthening construction techniques which minimize the introduction of new elements, (tuba sari, 2017) (akadiri p.o., 2012), allowing further studies related to numerical modelling, heritage rehabilitation and strengthening and also sustainability issues. the organization of the paper is the following: firstly the haussmann building complex is defined, secondly, the metallic and timber floors are described and the strengthening techniques are explained. finally, some conclusions are indicated. fig. 1 the haussmann building complex a) aerial view b) front view geometric characteristics of the structural floor elements was realized. resulting in a step description of the floors strengthening technique used. we strongly believe this paper will allow to better understand the actual floor strengthening construction techniques which minimize the introduction of new elements, (tuba sari, 2017) (akadiri p.o., 2012), allowing further studies related to numerical modelling, heritage rehabilitation and strengthening and also sustainability issues. the organization of the paper is the following: firstly the haussmann building complex is defined, secondly, the metallic and timber floors are described and the strengthening techniques are explained. finally, some conclusions are indicated. a) aerial view b) front view fig. 1. the haussmann building complex 2the haussmann floors the building complex is constituted by two haussmann buildings, built between 1830 and 1841. malhesherbe building on the left and madeleine building on the right in fig. 1-a). malhesherbe building as a gross floor area of 365 m2 and 7 stories and madeleine building as a gross floor area 416 m2 and 6 stories. the ground floor of the two buildings has a commercial use and the basement floor is used as a storage and to the technical equipment. the other floors are used for office purposes and housing. site observations allowed to conclude that the structure is highly composite and conceived essentially with local materials. the main haussmann facades are made of dressed stone, excepted the two upper floors which are made with a timber frame solution. the facades located in the backside are made with a timber frame or steel frame solution. fig. 2-a) shows malhesherbe and madeleine buildings facades viewed from malhesherbe boulevard, this is a typical haussmann facade and fig. 2b) shows an elevation along the building complex. a) front facade b) elevation fig. 2. malhesherbe and madeleine building complex geometric characteristics of the structural floor elements was realized. resulting in a step description of the floors strengthening technique used. we strongly believe this paper will allow to better understand the actual floor strengthening construction techniques which minimize the introduction of new elements, (tuba sari, 2017) (akadiri p.o., 2012), allowing further studies related to numerical modelling, heritage rehabilitation and strengthening and also sustainability issues. the organization of the paper is the following: firstly the haussmann building complex is defined, secondly, the metallic and timber floors are described and the strengthening techniques are explained. finally, some conclusions are indicated. a) aerial view b) front view fig. 1. the haussmann building complex 2the haussmann floors the building complex is constituted by two haussmann buildings, built between 1830 and 1841. malhesherbe building on the left and madeleine building on the right in fig. 1-a). malhesherbe building as a gross floor area of 365 m2 and 7 stories and madeleine building as a gross floor area 416 m2 and 6 stories. the ground floor of the two buildings has a commercial use and the basement floor is used as a storage and to the technical equipment. the other floors are used for office purposes and housing. site observations allowed to conclude that the structure is highly composite and conceived essentially with local materials. the main haussmann facades are made of dressed stone, excepted the two upper floors which are made with a timber frame solution. the facades located in the backside are made with a timber frame or steel frame solution. fig. 2-a) shows malhesherbe and madeleine buildings facades viewed from malhesherbe boulevard, this is a typical haussmann facade and fig. 2b) shows an elevation along the building complex. a) front facade b) elevation fig. 2. malhesherbe and madeleine building complex the building complex is constituted by two haussmann buildings, built between 1830 and 1841. malhesherbe building on the left and madeleine building on the right in fig. 1-a). malhesherbe building as a gross floor area of 365 m2 and 7 stories and madeleine building as a gross floor area 416 m2 and 6 stories. the ground floor of the two buildings has a commercial use and the basement floor is used as a storage and to the technical equipment. the other floors are used for office purposes and housing. site observations allowed to conclude that the structure is highly composite and conceived essentially with local materials. the main haussmann facades are made of dressed stone, excepted the two upper floors which are made with a timber frame solution. the facades located in the backside are made with a timber frame or steel frame solution. fig. 2-a) shows malhesherbe and madeleine buildings facades viewed from malhesherbe boulevard, this is a typical haussmann facade and fig. 2-b) shows an elevation along the building complex. fig. 2 malhesherbe and madeleine building complex a) front facade b) elevation geometric characteristics of the structural floor elements was realized. resulting in a step description of the floors strengthening technique used. we strongly believe this paper will allow to better understand the actual floor strengthening construction techniques which minimize the introduction of new elements, (tuba sari, 2017) (akadiri p.o., 2012), allowing further studies related to numerical modelling, heritage rehabilitation and strengthening and also sustainability issues. the organization of the paper is the following: firstly the haussmann building complex is defined, secondly, the metallic and timber floors are described and the strengthening techniques are explained. finally, some conclusions are indicated. a) aerial view b) front view fig. 1. the haussmann building complex 2the haussmann floors the building complex is constituted by two haussmann buildings, built between 1830 and 1841. malhesherbe building on the left and madeleine building on the right in fig. 1-a). malhesherbe building as a gross floor area of 365 m2 and 7 stories and madeleine building as a gross floor area 416 m2 and 6 stories. the ground floor of the two buildings has a commercial use and the basement floor is used as a storage and to the technical equipment. the other floors are used for office purposes and housing. site observations allowed to conclude that the structure is highly composite and conceived essentially with local materials. the main haussmann facades are made of dressed stone, excepted the two upper floors which are made with a timber frame solution. the facades located in the backside are made with a timber frame or steel frame solution. fig. 2-a) shows malhesherbe and madeleine buildings facades viewed from malhesherbe boulevard, this is a typical haussmann facade and fig. 2b) shows an elevation along the building complex. a) front facade b) elevation fig. 2. malhesherbe and madeleine building complex geometric characteristics of the structural floor elements was realized. resulting in a step description of the floors strengthening technique used. we strongly believe this paper will allow to better understand the actual floor strengthening construction techniques which minimize the introduction of new elements, (tuba sari, 2017) (akadiri p.o., 2012), allowing further studies related to numerical modelling, heritage rehabilitation and strengthening and also sustainability issues. the organization of the paper is the following: firstly the haussmann building complex is defined, secondly, the metallic and timber floors are described and the strengthening techniques are explained. finally, some conclusions are indicated. a) aerial view b) front view fig. 1. the haussmann building complex 2the haussmann floors the building complex is constituted by two haussmann buildings, built between 1830 and 1841. malhesherbe building on the left and madeleine building on the right in fig. 1-a). malhesherbe building as a gross floor area of 365 m2 and 7 stories and madeleine building as a gross floor area 416 m2 and 6 stories. the ground floor of the two buildings has a commercial use and the basement floor is used as a storage and to the technical equipment. the other floors are used for office purposes and housing. site observations allowed to conclude that the structure is highly composite and conceived essentially with local materials. the main haussmann facades are made of dressed stone, excepted the two upper floors which are made with a timber frame solution. the facades located in the backside are made with a timber frame or steel frame solution. fig. 2-a) shows malhesherbe and madeleine buildings facades viewed from malhesherbe boulevard, this is a typical haussmann facade and fig. 2b) shows an elevation along the building complex. a) front facade b) elevation fig. 2. malhesherbe and madeleine building complex journal of sustainable architecture and civil engineering 2018/2/23 18 the interior walls are made with bricks or a timber structure filled with limestone. the basement walls located in the building complex perimeter are limestone rubble masonry, while the interior walls can be made with limestone rubble masonry or clay bricks. foundation investigations revealed that the foundations of the existing walls are essentially realized extending downward the walls from 15 cm to 1 meter below the ground. sometimes a concrete or limestone masonry strip footing or a limestone footing is placed beneath the walls. the floors structural system are of two types. the first type refers to floors made of a timber joist with floorboards attached to it and the second type is related to a floor system realized with a metallic joist and plaster interjoists. all the stories of malhesherbe building are made with timber floors, while in madeleine building and fig. 3 timber floors a) laths and plaster under beams b) laths and plaster bellow beams fig. 4 timber floors a) timber floor view b) timber floor detail the interior walls are made with bricks or a timber structure filled with limestone. the basement walls located in the building complex perimeter are limestone rubble masonry, while the interior walls can be made with limestone rubble masonry or clay bricks. foundation investigations revealed that the foundations of the existing walls are essentially realized extending downward the walls from 15 cm to 1 meter below the ground. sometimes a concrete or limestone masonry strip footing or a limestone footing is placed beneath the walls. the floors structural system are of two types. the first type refers to floors made of a timber joist with floorboards attached to it and the second type is related to a floor system realized with a metallic joist and plaster interjoists. all the stories of malhesherbe building are made with timber floors, while in madeleine building and starting in the third floor, iao metallic profiles, the existing metallic profiles prior to the actual ipe/ipn profiles, are the solution considered for the floors. this distribution clearly indicates a technical evolution from timber floors to metallic floors. 2.1 timber floors the investigations have shown that the timber floors do not have more the required resistance and stiffness to safely carry the loads. several beams present large deformations or have extensive cracks. a weakening due to attacks by wood-eating insects and fungi is also evident. furthermore, the floorboards are clearly deformed by the normal decay. these floors are made with resistant timber beams made of massif oak, below theme there is the floor ceiling made with laths and plaster attached and under the beams, fig. 3-a), laths and a mortar support the floorboard revetment, as shown in fig 3b), (cardoso r. and pinto j., 2015). a) laths and plaster under beams b) laths and plaster bellow beams fig. 3. timber floors the technical survey performed on several timber floors, fig. 4-a), allow identifying different typologies along the stories. more than sixteen type of floors were identified, varying the dimensions of the timber beams and their spacing, fig. 4-b). the spacing (l) between beams varies 16 to 30 cm, the width (b) of the beams varies between 7 cm and 12 cm and can exceptionally reach 24 cm and finally, the beam height (h) varies from 15 cm to 26 cm. h b l a) timber floor view b) timber floor detail fig. 4. timber floors the interior walls are made with bricks or a timber structure filled with limestone. the basement walls located in the building complex perimeter are limestone rubble masonry, while the interior walls can be made with limestone rubble masonry or clay bricks. foundation investigations revealed that the foundations of the existing walls are essentially realized extending downward the walls from 15 cm to 1 meter below the ground. sometimes a concrete or limestone masonry strip footing or a limestone footing is placed beneath the walls. the floors structural system are of two types. the first type refers to floors made of a timber joist with floorboards attached to it and the second type is related to a floor system realized with a metallic joist and plaster interjoists. all the stories of malhesherbe building are made with timber floors, while in madeleine building and starting in the third floor, iao metallic profiles, the existing metallic profiles prior to the actual ipe/ipn profiles, are the solution considered for the floors. this distribution clearly indicates a technical evolution from timber floors to metallic floors. 2.1 timber floors the investigations have shown that the timber floors do not have more the required resistance and stiffness to safely carry the loads. several beams present large deformations or have extensive cracks. a weakening due to attacks by wood-eating insects and fungi is also evident. furthermore, the floorboards are clearly deformed by the normal decay. these floors are made with resistant timber beams made of massif oak, below theme there is the floor ceiling made with laths and plaster attached and under the beams, fig. 3-a), laths and a mortar support the floorboard revetment, as shown in fig 3b), (cardoso r. and pinto j., 2015). a) laths and plaster under beams b) laths and plaster bellow beams fig. 3. timber floors the technical survey performed on several timber floors, fig. 4-a), allow identifying different typologies along the stories. more than sixteen type of floors were identified, varying the dimensions of the timber beams and their spacing, fig. 4-b). the spacing (l) between beams varies 16 to 30 cm, the width (b) of the beams varies between 7 cm and 12 cm and can exceptionally reach 24 cm and finally, the beam height (h) varies from 15 cm to 26 cm. h b l a) timber floor view b) timber floor detail fig. 4. timber floors the interior walls are made with bricks or a timber structure filled with limestone. the basement walls located in the building complex perimeter are limestone rubble masonry, while the interior walls can be made with limestone rubble masonry or clay bricks. foundation investigations revealed that the foundations of the existing walls are essentially realized extending downward the walls from 15 cm to 1 meter below the ground. sometimes a concrete or limestone masonry strip footing or a limestone footing is placed beneath the walls. the floors structural system are of two types. the first type refers to floors made of a timber joist with floorboards attached to it and the second type is related to a floor system realized with a metallic joist and plaster interjoists. all the stories of malhesherbe building are made with timber floors, while in madeleine building and starting in the third floor, iao metallic profiles, the existing metallic profiles prior to the actual ipe/ipn profiles, are the solution considered for the floors. this distribution clearly indicates a technical evolution from timber floors to metallic floors. 2.1 timber floors the investigations have shown that the timber floors do not have more the required resistance and stiffness to safely carry the loads. several beams present large deformations or have extensive cracks. a weakening due to attacks by wood-eating insects and fungi is also evident. furthermore, the floorboards are clearly deformed by the normal decay. these floors are made with resistant timber beams made of massif oak, below theme there is the floor ceiling made with laths and plaster attached and under the beams, fig. 3-a), laths and a mortar support the floorboard revetment, as shown in fig 3b), (cardoso r. and pinto j., 2015). a) laths and plaster under beams b) laths and plaster bellow beams fig. 3. timber floors the technical survey performed on several timber floors, fig. 4-a), allow identifying different typologies along the stories. more than sixteen type of floors were identified, varying the dimensions of the timber beams and their spacing, fig. 4-b). the spacing (l) between beams varies 16 to 30 cm, the width (b) of the beams varies between 7 cm and 12 cm and can exceptionally reach 24 cm and finally, the beam height (h) varies from 15 cm to 26 cm. h b l a) timber floor view b) timber floor detail fig. 4. timber floors the interior walls are made with bricks or a timber structure filled with limestone. the basement walls located in the building complex perimeter are limestone rubble masonry, while the interior walls can be made with limestone rubble masonry or clay bricks. foundation investigations revealed that the foundations of the existing walls are essentially realized extending downward the walls from 15 cm to 1 meter below the ground. sometimes a concrete or limestone masonry strip footing or a limestone footing is placed beneath the walls. the floors structural system are of two types. the first type refers to floors made of a timber joist with floorboards attached to it and the second type is related to a floor system realized with a metallic joist and plaster interjoists. all the stories of malhesherbe building are made with timber floors, while in madeleine building and starting in the third floor, iao metallic profiles, the existing metallic profiles prior to the actual ipe/ipn profiles, are the solution considered for the floors. this distribution clearly indicates a technical evolution from timber floors to metallic floors. 2.1 timber floors the investigations have shown that the timber floors do not have more the required resistance and stiffness to safely carry the loads. several beams present large deformations or have extensive cracks. a weakening due to attacks by wood-eating insects and fungi is also evident. furthermore, the floorboards are clearly deformed by the normal decay. these floors are made with resistant timber beams made of massif oak, below theme there is the floor ceiling made with laths and plaster attached and under the beams, fig. 3-a), laths and a mortar support the floorboard revetment, as shown in fig 3b), (cardoso r. and pinto j., 2015). a) laths and plaster under beams b) laths and plaster bellow beams fig. 3. timber floors the technical survey performed on several timber floors, fig. 4-a), allow identifying different typologies along the stories. more than sixteen type of floors were identified, varying the dimensions of the timber beams and their spacing, fig. 4-b). the spacing (l) between beams varies 16 to 30 cm, the width (b) of the beams varies between 7 cm and 12 cm and can exceptionally reach 24 cm and finally, the beam height (h) varies from 15 cm to 26 cm. h b l a) timber floor view b) timber floor detail fig. 4. timber floors starting in the third floor, iao metallic profiles, the existing metallic profiles prior to the actual ipe/ ipn profiles, are the solution considered for the floors. this distribution clearly indicates a technical evolution from timber floors to metallic floors. timber floors the investigations have shown that the timber floors do not have more the required resistance and stiffness to safely carry the loads. several beams present large deformations or have extensive cracks. a weakening due to attacks by wood-eating insects and fungi is also evident. furthermore, the floorboards are clearly deformed by the normal decay. these floors are made with resistant timber beams made of massif oak, below theme there is the floor ceiling made with laths and plaster attached and under the beams, fig. 3-a), laths and a mortar support the floorboard revetment, as shown in fig 3-b), (cardoso r. and pinto j., 2015). the technical survey performed on several timber floors, fig. 4-a), allow identifying different typologies along the stories. more than sixteen type of floors were identified, varying the dimensions of the timber beams and their spacing, fig. 4-b). the spacing (l) between beams varies 16 to 30 cm, the width (b) of the beams varies between 7 cm and 12 cm and can exceptionally reach 24 cm and finally, the beam height (h) varies from 15 cm to 26 cm. strengthening technique the rehabilitation works plan to this complex consider the rehabilitation and strengthening of several timber floors because they do not have the necessary load carrying capacity, but also because regarding the overall building stability they do not brace correctly the structure against possible horizontal movements of the facade, (branco, 2006). the strengthening work consists in pouring a new concrete slab under the existing timber beams. in 19 journal of sustainable architecture and civil engineering 2018/2/23 this operation, all the connected slab have 8 cm thickness. in order to realize this work, we must consider 6 steps. the initial state of the timber pavement is illustrated in fig. 5 and represented by the existing timber beams and a lath and plaster layer. fig. 5 initial state 2.2 strengthening technique the rehabilitation works plan to this complex consider the rehabilitation and strengthening of several timber floors because they do not have the necessary load carrying capacity, but also because regarding the overall building stability they do not brace correctly the structure against possible horizontal movements of the facade, (branco, 2006). the strengthening work consists in pouring a new concrete slab under the existing timber beams. in this operation, all the connected slab have 8 cm thickness. in order to realize this work, we must consider 6 steps. the initial state of the timber pavement is illustrated in fig. 5 and represented by the existing timber beams and a lath and plaster layer. fig. 5. initial state in the first step, the existing lath and plaster layer elements are eliminated, a shoring tower tour is necessary. this shoring tower has beams and a lost formwork, fig. 6. fig. 6. existing timber pavement elimination in the second step, timber boards are put laterally on the timber beams which will be connected to the future concrete slab and cushioning timber elements are put on the timber beams which will be not connected, as illustrated in fig. 7. fig. 7. timber boards in the third step, a lost formwork is put under the timber boards and on the cushioning timber elements to pour the concrete slab. finally, the shoring tower is moved to another area and the previous operations are repeated, fig. 8. 2.2 strengthening technique the rehabilitation works plan to this complex consider the rehabilitation and strengthening of several timber floors because they do not have the necessary load carrying capacity, but also because regarding the overall building stability they do not brace correctly the structure against possible horizontal movements of the facade, (branco, 2006). the strengthening work consists in pouring a new concrete slab under the existing timber beams. in this operation, all the connected slab have 8 cm thickness. in order to realize this work, we must consider 6 steps. the initial state of the timber pavement is illustrated in fig. 5 and represented by the existing timber beams and a lath and plaster layer. fig. 5. initial state in the first step, the existing lath and plaster layer elements are eliminated, a shoring tower tour is necessary. this shoring tower has beams and a lost formwork, fig. 6. fig. 6. existing timber pavement elimination in the second step, timber boards are put laterally on the timber beams which will be connected to the future concrete slab and cushioning timber elements are put on the timber beams which will be not connected, as illustrated in fig. 7. fig. 7. timber boards in the third step, a lost formwork is put under the timber boards and on the cushioning timber elements to pour the concrete slab. finally, the shoring tower is moved to another area and the previous operations are repeated, fig. 8. 2.2 strengthening technique the rehabilitation works plan to this complex consider the rehabilitation and strengthening of several timber floors because they do not have the necessary load carrying capacity, but also because regarding the overall building stability they do not brace correctly the structure against possible horizontal movements of the facade, (branco, 2006). the strengthening work consists in pouring a new concrete slab under the existing timber beams. in this operation, all the connected slab have 8 cm thickness. in order to realize this work, we must consider 6 steps. the initial state of the timber pavement is illustrated in fig. 5 and represented by the existing timber beams and a lath and plaster layer. fig. 5. initial state in the first step, the existing lath and plaster layer elements are eliminated, a shoring tower tour is necessary. this shoring tower has beams and a lost formwork, fig. 6. fig. 6. existing timber pavement elimination in the second step, timber boards are put laterally on the timber beams which will be connected to the future concrete slab and cushioning timber elements are put on the timber beams which will be not connected, as illustrated in fig. 7. fig. 7. timber boards in the third step, a lost formwork is put under the timber boards and on the cushioning timber elements to pour the concrete slab. finally, the shoring tower is moved to another area and the previous operations are repeated, fig. 8. fig. 6 existing timber pavement elimination fig. 7 timber boards in the first step, the existing lath and plaster layer elements are eliminated, a shoring tower tour is necessary. this shoring tower has beams and a lost formwork, fig. 6. in the second step, timber boards are put laterally on the timber beams which will be connected to the future concrete slab and cushioning timber elements are put on the timber beams which will be not connected, as illustrated in fig. 7. in the third step, a lost formwork is put under the timber boards and on the cushioning timber elements to pour the concrete slab. finally, the shoring tower is moved to another area and the previous operations are repeated, fig. 8. in the fourth step, connectors are put in place, their spacing and number are obtained after calculations, fig. 9. in the fifth step, the reinforcement corresponding to the concrete slab is put in place, fig. 10. each time the shoring tower is not used it must be validated by the design office. journal of sustainable architecture and civil engineering 2018/2/23 20 finally in the sixth step, after putting in place the shoring tower under the beams, following the studies performed by the design office, the slab is poured with a concrete pump, fig. 11. fig. 10 reinforcement introdution fig. 9 connectors fig. 8 lost formwork fig. 8. lost formwork in the fourth step, connectors are put in place, their spacing and number are obtained after calculations, fig. 9. fig. 9. connectors in the fifth step, the reinforcement corresponding to the concrete slab is put in place, fig. 10. each time the shoring tower is not used it must be validated by the design office. fig. 10. reinforcement introdution finally in the sixth step, after putting in place the shoring tower under the beams, following the studies performed by the design office, the slab is poured with a concrete pump, fig. 11. fig. 11. concrete slab connected fig. 11. clearly shows that this technique allowed to maintain an important quantity of existing materials and therefore it can be classified as a sustainable strengthening technique. this will not have been the case if instead a complete 20-25 cm thickness traditional concrete slab should have been poured. fig. 8. lost formwork in the fourth step, connectors are put in place, their spacing and number are obtained after calculations, fig. 9. fig. 9. connectors in the fifth step, the reinforcement corresponding to the concrete slab is put in place, fig. 10. each time the shoring tower is not used it must be validated by the design office. fig. 10. reinforcement introdution finally in the sixth step, after putting in place the shoring tower under the beams, following the studies performed by the design office, the slab is poured with a concrete pump, fig. 11. fig. 11. concrete slab connected fig. 11. clearly shows that this technique allowed to maintain an important quantity of existing materials and therefore it can be classified as a sustainable strengthening technique. this will not have been the case if instead a complete 20-25 cm thickness traditional concrete slab should have been poured. fig. 8. lost formwork in the fourth step, connectors are put in place, their spacing and number are obtained after calculations, fig. 9. fig. 9. connectors in the fifth step, the reinforcement corresponding to the concrete slab is put in place, fig. 10. each time the shoring tower is not used it must be validated by the design office. fig. 10. reinforcement introdution finally in the sixth step, after putting in place the shoring tower under the beams, following the studies performed by the design office, the slab is poured with a concrete pump, fig. 11. fig. 11. concrete slab connected fig. 11. clearly shows that this technique allowed to maintain an important quantity of existing materials and therefore it can be classified as a sustainable strengthening technique. this will not have been the case if instead a complete 20-25 cm thickness traditional concrete slab should have been poured. fig. 11 concrete slab connected fig. 8. lost formwork in the fourth step, connectors are put in place, their spacing and number are obtained after calculations, fig. 9. fig. 9. connectors in the fifth step, the reinforcement corresponding to the concrete slab is put in place, fig. 10. each time the shoring tower is not used it must be validated by the design office. fig. 10. reinforcement introdution finally in the sixth step, after putting in place the shoring tower under the beams, following the studies performed by the design office, the slab is poured with a concrete pump, fig. 11. fig. 11. concrete slab connected fig. 11. clearly shows that this technique allowed to maintain an important quantity of existing materials and therefore it can be classified as a sustainable strengthening technique. this will not have been the case if instead a complete 20-25 cm thickness traditional concrete slab should have been poured. fig. 11. clearly shows that this technique allowed to maintain an important quantity of existing materials and therefore it can be classified as a sustainable strengthening technique. this will not have been the case if instead a complete 20-25 cm thickness traditional concrete slab should have been poured. the metallic floors some floors are made of metallic beams, in fact, starting on the 3rd floor of madeleine building, the floors are realized with metal beams constituted of iao cross-sections, fig.12 a). between 21 journal of sustainable architecture and civil engineering 2018/2/23 fig. 12 metallic iao floors a ) metallic floor b) metallic floor detail 2.3 the metallic floors some floors are made of metallic beams, in fact, starting on the 3rd floor of madeleine building, the floors are realized with metal beams constituted of iao cross-sections, fig.12 a). between those beams, plaster interjoist elements are set, fig. 12-b). the investigation on metallic iao profiles indicated high deflections and plaster cover deterioration. furthermore, the design calculations indicate also that those floors do not have the necessary resistance to withstand the new loads rising from the new regulations (en 1991-1-1, 2002) and due to the new service conditions, corresponding to a hotel. a ) metallic floor b) metallic floor detail fig. 12. metallic iao floors investigation on the metallic iao profiles allowed to identify three types of metallic floors, depending one the iao dimensions, the results are indicated in table 1 and relative to madeleine building. table 1. iao cross-section dimensions cross-section dimensions (cm) floor designation flanges width height spacing 4th d1 6 16 63 5th d2 6 16 60 d3 6 16 58 the flanges width of the iao profiles is equal to 6 cm, the height to 16 cm and the spacing between beams varies from 58 to 63 cm. beyond that, tensile tests ordered to veritas office and realized in iao cross-section beams indicated a yield strength varying from 258 mpa and 283 mpa, and a young modulus varying from 179 to 187 gpa. these results indicate that the metallic profiles still present good mechanical characteristics, in fact, the actual minimum tensile yield strength for metallic profiles is 360 mpa and the young modulus is 200 gpa, (en 1993-1-1, 2005). the protection given by the existing plaster infill around the metallic profiles certainly justifies those values (cardoso et al., 2016). 2.4 strengthening techniques the strengthening technique for the existing metallic floors consists in maintaining the iao profiles and creating a new concrete slab. three solutions can be considered, in the first a concrete slab is connected to the metallic iao profiles, the existing plaster interjoist is kept in place, fig. 13 illustrates this solution. the thickness of the connected concrete slab can vary between 8 and 12 cm. 2.3 the metallic floors some floors are made of metallic beams, in fact, starting on the 3rd floor of madeleine building, the floors are realized with metal beams constituted of iao cross-sections, fig.12 a). between those beams, plaster interjoist elements are set, fig. 12-b). the investigation on metallic iao profiles indicated high deflections and plaster cover deterioration. furthermore, the design calculations indicate also that those floors do not have the necessary resistance to withstand the new loads rising from the new regulations (en 1991-1-1, 2002) and due to the new service conditions, corresponding to a hotel. a ) metallic floor b) metallic floor detail fig. 12. metallic iao floors investigation on the metallic iao profiles allowed to identify three types of metallic floors, depending one the iao dimensions, the results are indicated in table 1 and relative to madeleine building. table 1. iao cross-section dimensions cross-section dimensions (cm) floor designation flanges width height spacing 4th d1 6 16 63 5th d2 6 16 60 d3 6 16 58 the flanges width of the iao profiles is equal to 6 cm, the height to 16 cm and the spacing between beams varies from 58 to 63 cm. beyond that, tensile tests ordered to veritas office and realized in iao cross-section beams indicated a yield strength varying from 258 mpa and 283 mpa, and a young modulus varying from 179 to 187 gpa. these results indicate that the metallic profiles still present good mechanical characteristics, in fact, the actual minimum tensile yield strength for metallic profiles is 360 mpa and the young modulus is 200 gpa, (en 1993-1-1, 2005). the protection given by the existing plaster infill around the metallic profiles certainly justifies those values (cardoso et al., 2016). 2.4 strengthening techniques the strengthening technique for the existing metallic floors consists in maintaining the iao profiles and creating a new concrete slab. three solutions can be considered, in the first a concrete slab is connected to the metallic iao profiles, the existing plaster interjoist is kept in place, fig. 13 illustrates this solution. the thickness of the connected concrete slab can vary between 8 and 12 cm. those beams, plaster interjoist elements are set, fig. 12-b). the investigation on metallic iao profiles indicated high deflections and plaster cover deterioration. furthermore, the design calculations indicate also that those floors do not have the necessary resistance to withstand the new loads rising from the new regulations (en 1991-1-1, 2002) and due to the new service conditions, corresponding to a hotel. investigation on the metallic iao profiles allowed to identify three types of metallic floors, depending one the iao dimensions, the results are indicated in table 1 and relative to madeleine building. the flanges width of the iao profiles is equal to 6 cm, the height to 16 cm and the spacing between beams varies from 58 to 63 cm. beyond that, tensile tests ordered to veritas office and realized in iao cross-section beams indicated a yield strength varying from 258 mpa and 283 mpa, and a young modulus varying from 179 to 187 gpa. these results indicate that the metallic profiles still present good mechanical characteristics, in fact, the actual minimum tensile yield strength for metallic profiles is 360 mpa and the young modulus is 200 gpa, (en 1993-1-1, 2005). the protection given by the existing plaster infill around the metallic profiles certainly justifies those values (cardoso et al., 2016). strengthening techniques the strengthening technique for the existing metallic floors consists in maintaining the iao profiles and table 1 iao cross-section dimensions cross-section dimensions (cm) floor designation flanges width height spacing 4th d1 6 16 63 5th d2 6 16 60 d3 6 16 58 fig. 13. connected concrete slab the second solution, consider the elimination of the plaster interjoist, only the metallic iao profiles are maintained in place. a traditional reinforced concrete slab is put in place. in this solution, the resistance of the floor is the sum of a concrete slab plus the resistance obtained from the iao profiles, fig.14. fig. 14. full concrete slab finally, a third solution, intermediate between the first and the second solution can be considered. the plaster interjoist is partially eliminated and a concrete slab is poured. in terms of resistance, we can also consider that the resistance of this floor is given by the sum of the iao resistance and the reinforced concrete slab, fig. 15. fig. 15. concrete slab in the followings, we introduce the several steps regarding the strengthening of a metallic floor with a connected concrete slab, corresponding to the first solution, fig.13. in the first step, the metallic floor is cleaned and only the iao profiles and the plaster interjoist are maintained, this corresponds to the initial state, fig. 16. fig. 16. initial state secondly, a lightweight concrete is added in the volume between the interjoist and the top of the iao profile, fig. 17. creating a new concrete slab. three solutions can be considered, in the first a concrete slab is connected to the metallic iao profiles, the existing plaster interjoist is kept in place, fig. 13 illustrates this solution. the thickness of the connected concrete slab can vary between 8 and 12 cm. the second solution, consider the elimination of the plaster interjoist, only the metallic iao profiles fig. 13 connected concrete slab journal of sustainable architecture and civil engineering 2018/2/23 22 are maintained in place. a traditional reinforced concrete slab is put in place. in this solution, the resistance of the floor is the sum of a concrete slab plus the resistance obtained from the iao profiles, fig.14. finally, a third solution, intermediate between the first and the second solution can be considered. the plaster interjoist is partially eliminated and a concrete slab is poured. in terms of resistance, we can also consider that the resistance of this floor is given fig. 14 full concrete slab fig. 15 concrete slab fig. 16 initial state fig. 17 lightweight concrete fig. 18 steel connectors fig. 13. connected concrete slab the second solution, consider the elimination of the plaster interjoist, only the metallic iao profiles are maintained in place. a traditional reinforced concrete slab is put in place. in this solution, the resistance of the floor is the sum of a concrete slab plus the resistance obtained from the iao profiles, fig.14. fig. 14. full concrete slab finally, a third solution, intermediate between the first and the second solution can be considered. the plaster interjoist is partially eliminated and a concrete slab is poured. in terms of resistance, we can also consider that the resistance of this floor is given by the sum of the iao resistance and the reinforced concrete slab, fig. 15. fig. 15. concrete slab in the followings, we introduce the several steps regarding the strengthening of a metallic floor with a connected concrete slab, corresponding to the first solution, fig.13. in the first step, the metallic floor is cleaned and only the iao profiles and the plaster interjoist are maintained, this corresponds to the initial state, fig. 16. fig. 16. initial state secondly, a lightweight concrete is added in the volume between the interjoist and the top of the iao profile, fig. 17. fig. 13. connected concrete slab the second solution, consider the elimination of the plaster interjoist, only the metallic iao profiles are maintained in place. a traditional reinforced concrete slab is put in place. in this solution, the resistance of the floor is the sum of a concrete slab plus the resistance obtained from the iao profiles, fig.14. fig. 14. full concrete slab finally, a third solution, intermediate between the first and the second solution can be considered. the plaster interjoist is partially eliminated and a concrete slab is poured. in terms of resistance, we can also consider that the resistance of this floor is given by the sum of the iao resistance and the reinforced concrete slab, fig. 15. fig. 15. concrete slab in the followings, we introduce the several steps regarding the strengthening of a metallic floor with a connected concrete slab, corresponding to the first solution, fig.13. in the first step, the metallic floor is cleaned and only the iao profiles and the plaster interjoist are maintained, this corresponds to the initial state, fig. 16. fig. 16. initial state secondly, a lightweight concrete is added in the volume between the interjoist and the top of the iao profile, fig. 17. fig. 13. connected concrete slab the second solution, consider the elimination of the plaster interjoist, only the metallic iao profiles are maintained in place. a traditional reinforced concrete slab is put in place. in this solution, the resistance of the floor is the sum of a concrete slab plus the resistance obtained from the iao profiles, fig.14. fig. 14. full concrete slab finally, a third solution, intermediate between the first and the second solution can be considered. the plaster interjoist is partially eliminated and a concrete slab is poured. in terms of resistance, we can also consider that the resistance of this floor is given by the sum of the iao resistance and the reinforced concrete slab, fig. 15. fig. 15. concrete slab in the followings, we introduce the several steps regarding the strengthening of a metallic floor with a connected concrete slab, corresponding to the first solution, fig.13. in the first step, the metallic floor is cleaned and only the iao profiles and the plaster interjoist are maintained, this corresponds to the initial state, fig. 16. fig. 16. initial state secondly, a lightweight concrete is added in the volume between the interjoist and the top of the iao profile, fig. 17. fig. 13. connected concrete slab the second solution, consider the elimination of the plaster interjoist, only the metallic iao profiles are maintained in place. a traditional reinforced concrete slab is put in place. in this solution, the resistance of the floor is the sum of a concrete slab plus the resistance obtained from the iao profiles, fig.14. fig. 14. full concrete slab finally, a third solution, intermediate between the first and the second solution can be considered. the plaster interjoist is partially eliminated and a concrete slab is poured. in terms of resistance, we can also consider that the resistance of this floor is given by the sum of the iao resistance and the reinforced concrete slab, fig. 15. fig. 15. concrete slab in the followings, we introduce the several steps regarding the strengthening of a metallic floor with a connected concrete slab, corresponding to the first solution, fig.13. in the first step, the metallic floor is cleaned and only the iao profiles and the plaster interjoist are maintained, this corresponds to the initial state, fig. 16. fig. 16. initial state secondly, a lightweight concrete is added in the volume between the interjoist and the top of the iao profile, fig. 17. fig. 17. lightweight concrete thirdly, hilti x-hvb steel connectors are put in the top of the iao profiles, the spacing and number of connectors being calculated by the design office, fig. 18. fig. 18. steel connectors fourthly, since the iao profiles do not have necessarily the same height, polystyrene boards are put in place in order to create a perfectly horizontal surface, fig. 19. fig. 19. polystyrene boards fifthly, the slab reinforcement is added, fig. 20. fig. 20. slab reinforcement finally, the concrete slab is poured, fig. 21. fig. 21. concrete slab it should be noted that the connectors used are 50 mm, 80 mm, 125 mm or 140 mm height, depending on the iao profiles height. conclusions the planning and design of strengthening techniques play a very important role in the global sustainable development. the demand for strengthening has increased in the last years as renewals and refurbishment of old buildings have gained popularity, mainly in the european oldest cities. this type of work requires skilled labor, not only constructors but also in the planning stage, since there is not a universal solution applicable to all cases. the rehabilitation and strengthening work realized in the floors intended among others to eliminate their pathologies and increase their resistance and stiffness. the strengthening technique described for the floors is essentially based on pouring a concrete slab connected to the timber beams or to the iao by the sum of the iao resistance and the reinforced concrete slab, fig. 15. in the followings, we introduce the several steps regarding the strengthening of a metallic floor with a connected concrete slab, corresponding to the first solution, fig.13. in the first step, the metallic floor is cleaned and only the iao profiles and the plaster interjoist are maintained, this corresponds to the initial state, fig. 16. secondly, a lightweight concrete is added in the volume between the interjoist and the top of the iao profile, fig. 17. thirdly, hilti x-hvb steel connectors are put in the top of the iao profiles, the spacing and number of connectors being calculated by the design office, fig. 18. 23 journal of sustainable architecture and civil engineering 2018/2/23 fig. 19 polystyrene boards fig. 20 slab reinforcement fig. 21 concrete slab fig. 17. lightweight concrete thirdly, hilti x-hvb steel connectors are put in the top of the iao profiles, the spacing and number of connectors being calculated by the design office, fig. 18. fig. 18. steel connectors fourthly, since the iao profiles do not have necessarily the same height, polystyrene boards are put in place in order to create a perfectly horizontal surface, fig. 19. fig. 19. polystyrene boards fifthly, the slab reinforcement is added, fig. 20. fig. 20. slab reinforcement finally, the concrete slab is poured, fig. 21. fig. 21. concrete slab it should be noted that the connectors used are 50 mm, 80 mm, 125 mm or 140 mm height, depending on the iao profiles height. conclusions the planning and design of strengthening techniques play a very important role in the global sustainable development. the demand for strengthening has increased in the last years as renewals and refurbishment of old buildings have gained popularity, mainly in the european oldest cities. this type of work requires skilled labor, not only constructors but also in the planning stage, since there is not a universal solution applicable to all cases. the rehabilitation and strengthening work realized in the floors intended among others to eliminate their pathologies and increase their resistance and stiffness. the strengthening technique described for the floors is essentially based on pouring a concrete slab connected to the timber beams or to the iao fourthly, since the iao profiles do not have necessarily the same height, polystyrene boards are put in place in order to create a perfectly horizontal surface, fig. 19. fifthly, the slab reinforcement is added, fig. 20. finally, the concrete slab is poured, fig. 21. it should be noted that the connectors used are 50 mm, 80 mm, 125 mm or 140 mm height, depending on the iao profiles height. fig. 17. lightweight concrete thirdly, hilti x-hvb steel connectors are put in the top of the iao profiles, the spacing and number of connectors being calculated by the design office, fig. 18. fig. 18. steel connectors fourthly, since the iao profiles do not have necessarily the same height, polystyrene boards are put in place in order to create a perfectly horizontal surface, fig. 19. fig. 19. polystyrene boards fifthly, the slab reinforcement is added, fig. 20. fig. 20. slab reinforcement finally, the concrete slab is poured, fig. 21. fig. 21. concrete slab it should be noted that the connectors used are 50 mm, 80 mm, 125 mm or 140 mm height, depending on the iao profiles height. conclusions the planning and design of strengthening techniques play a very important role in the global sustainable development. the demand for strengthening has increased in the last years as renewals and refurbishment of old buildings have gained popularity, mainly in the european oldest cities. this type of work requires skilled labor, not only constructors but also in the planning stage, since there is not a universal solution applicable to all cases. the rehabilitation and strengthening work realized in the floors intended among others to eliminate their pathologies and increase their resistance and stiffness. the strengthening technique described for the floors is essentially based on pouring a concrete slab connected to the timber beams or to the iao fig. 17. lightweight concrete thirdly, hilti x-hvb steel connectors are put in the top of the iao profiles, the spacing and number of connectors being calculated by the design office, fig. 18. fig. 18. steel connectors fourthly, since the iao profiles do not have necessarily the same height, polystyrene boards are put in place in order to create a perfectly horizontal surface, fig. 19. fig. 19. polystyrene boards fifthly, the slab reinforcement is added, fig. 20. fig. 20. slab reinforcement finally, the concrete slab is poured, fig. 21. fig. 21. concrete slab it should be noted that the connectors used are 50 mm, 80 mm, 125 mm or 140 mm height, depending on the iao profiles height. conclusions the planning and design of strengthening techniques play a very important role in the global sustainable development. the demand for strengthening has increased in the last years as renewals and refurbishment of old buildings have gained popularity, mainly in the european oldest cities. this type of work requires skilled labor, not only constructors but also in the planning stage, since there is not a universal solution applicable to all cases. the rehabilitation and strengthening work realized in the floors intended among others to eliminate their pathologies and increase their resistance and stiffness. the strengthening technique described for the floors is essentially based on pouring a concrete slab connected to the timber beams or to the iao the planning and design of strengthening techniques play a very important role in the global sustainable development. the demand for strengthening has increased in the last years as renewals and refurbishment of old buildings have gained popularity, mainly in the european oldest cities. this type of work requires skilled labor, not only constructors but also in the planning stage, since there is not a universal solution applicable to all cases. the rehabilitation and strengthening work realized in the floors intended among others to eliminate their pathologies and increase their resistance and stiffness. the strengthening technique described for the floors is essentially based on pouring a concrete slab connected to the timber beams or to the iao profiles. this strengthening technique retains a great amount of the original structure and minimizes the intervention and the introduction of new elements which lead to a cost-effective solution. it can be cataloged as a sustainable strengthening technique, ensuring at the same time to fulfill the actual requirements in terms of structural integrity, fire safety, thermal and soundproof insulation. acknowledgement the author would like to acknowledge julien dequeker, site engineer and paulo oliveira site manager, both from vinci construction, france, for their technical support. conclusions referencesakadiri p.o., chinyio e.a., olomalaiye p.o. design of sustainable buildings: a conceptual framework for implementing sustainability in the building sector, buildings, 2012, 2(1):126-152. https://doi. org/10.3390/buildings2020126 branco j., cruz p., piazza m. and varum h. strengthening techniques of portuguese traditional timber connections, structural analysis of historical constructions, p.b. lourenço, p. roca, c. modena, s. agrawal (eds.), new delhi, 2006. https://doi.org/10.3390/buildings2020126 https://doi.org/10.3390/buildings2020126 journal of sustainable architecture and civil engineering 2018/2/23 24 cardoso r., pinto j. tabique walls composite earth based material characterization in the alto douro wine region, portugal. constructii journal of civil engineering research, 2015, 16(2): 03 11. cardoso r., pinto j., paiva a. lanzinha j.c. tabique walls typologies and building details in the alto douro wine region. journal wseas transactions on environment and development, 2015, volume 11, art.11, pp.95-107. cardoso r., pinto j., pinto j., lanzinha j.c. characterization of tabique wall nails of the alto douro wine region, open engineering, 2016, 6(1):446-454. cardoso r., pinto j., paiva a., lanzinha j.c. earth-based material field tests characterization in the alto douro wine region. open engineering, 2017,6(1):435443. https://doi.org/10.1515/eng-2017-0048 catarig al., kopenetz l., structural problems of scafolds used in rehabilitation works of historical buildings, acta tech. napocensis: civil eng. & arch., 2007, vol. 50, 57-67. en 1991-1-1. eurocode 1: action on structures part 1-1: general actions – densities, self-weight, imposed loads for buildings, cen brussels, 2002. en 1993-1-1 eurocode 3: design of stell structures part 1-1: general rules and rules for buildings rules, cen brussels, 2005. froidevaux y. techniques de l’architecture ancienne: construction et restauration [ancient architecture technique: construction and restoration]. isbn 2-87009-774-3. pierre mardaga editeur, 1986. jomber c.a. architecture moderne, ou l’art de bien bâtir pour toutes sortes de personnes [moderne architecture or the good construction art for all types of persons], tome premier de la construction, librairie du génie et de l´artillerie , rue dauphine notre-dame, paris, 1764. jordan d.p. paris haussmann and after, jounal of urban history, 2015, 41(3): 541-549. lepoutre d. histoire d‘un immeuble haussmannien: catégories d‘habitants et rapports d‘habitation en milieu bourgeois [history of a haussmann building], revue française de sociologie, 2010, 51(2):321-358. https://doi.org/10.3917/rfs.512.0321 tuba sari. review on high-rise housing projects in istanbul: toward a sustainable architecture. journal of sustainable architecture and civil engineering, 2017, 18(1): 39-49. https://doi.org/10.5755/ j01.sace.18.1.16598 about the author rui cardoso ph.d fellow researcher civil engineering and architecture department, beira interior university main research area sustainable construction techniques address civil engineering and architecture department, beira interior university, 6201-001 covilhã, portugal tel. 0033 (0)6 27 85 82 48 e-mail: jcardoso@ubi.pt https://doi.org/10.1515/eng-2017-0048 https://doi.org/10.3917/rfs.512.0321 https://doi.org/10.5755/j01.sace.18.1.16598 https://doi.org/10.5755/j01.sace.18.1.16598 63 journal of sustainable architecture and civil engineering 2019/2/25 *corresponding author: tadas.zdankus@ktu.lt wind energy usage for building heating applying hydraulic system received 2018/08/30 accepted after revision 2018/12/03 journal of sustainable architecture and civil engineering vol. 2 / no. 25 / 2019 pp. 63-70 doi 10.5755/j01.sace.25.2.21542 wind energy usage for building heating applying hydraulic system jsace 2/25 http://dx.doi.org/10.5755/j01.sace.25.2.21542 tadas ždankus*, jurgita černeckienė, leonas greičius, vidas stanevičius, nerijus bunikis kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania introduction the most ordinary way to use wind energy for building heating needs is to convert mechanical wind energy into electrical energy and to use electrical energy for heating. though there are ways to convert mechanical wind energy into thermal energy without transitional energy conversion – hydraulic systems can be implemented for this purpose. wind rotor gives rotational motion to the pump of hydraulic system and it creates fluid circulation in the hydraulic system. a part of liquid mechanical energy due to hydraulic resistance of the system converts into the thermal energy when the liquid circulates in the close hydraulic loop and it heats up the liquid that can be used for heating purposes. different hydraulic valves can be integrated in the hydraulic system and they can work as the load-regulating component of the system. the purpose of the study was to adjust the hydraulic load to the optimal value in order to generate a maximum amount of thermal energy. during the study, the work of a wind rotor was simulated by an electric motor, rotated at different frequencies (without feedback). the hydraulic system consisted of a gear pump, an adjustable load regulation valve, pipes, oil tank, sensors for measuring motor shaft rotational speed, oil temperature and pressure. the experiments were carried out at different electromotor speeds: 12.5, 17.5 and 22.5 hz, and for different oil temperatures in the range of 20 to 50 °c. the relationship between the opening degree of the valve and the amount of generated thermal energy was determined. the study showed that wind energy usage can cover a significant part of the building’s thermal energy needs at the same time reducing pollution and the usage of the fossil fuel for heating purposes. keywords: energy conversion, heating of the building, heat production, hydraulic system, wind energy. in recent years, the questions on the usage of the sustainable and renewable energy resources are being solved considering various aspects. where earlier only the engineers or ecologists have solved the objectives related to this topic, then lately, we can hear more and more involvement of the politicians, sociologists and economists in this field (stigka et al. 2014). such questions are directly related to the problem of the climate warming, and the dominant feeling in the world shall condition determining the higher goals that would help managing or even stopping the climate changes. many factors have conditioned the leap forward in the field of the renewable energy resources – beginning from the decrease of the fossil fuels, increase the global energy needs, the aim to decrease the impact of the greenhouse effect on the ecological situation of the planet (katinas et al. 2014), etc. for the separate countries having not enough fossil fuels renewable energy usage is very important because of the economical wealth of the country and even sovereignty (katinas et al. 2014). journal of sustainable architecture and civil engineering 2019/2/25 64 one of the renewable energy resources that usage possibilities are analyzed further in this article is the mechanical wind energy. in its widest sense the primary source of the wind energy is the sun, but in the interest of clarity, it is necessary to say that there is a tradition to exclude between the direct usage of the sun radiation energy and energy forms emerged due to the sun radiation. wind energy usage for heating purposes is interesting as the study object because the changes of the demand for the heat energy for building heating during the year (černeckienė, 2015) is close to the distribution of the wind potential (according to the lithuanian climatology data). in addition, when the energy is used at the time of its production or in the near future, the question of the energy storage shall become less relevant. the system of wind energy usage (fig. 1) consists of a few analysis objects and units, such as conditions of the climatology area, design of the wind rotor, energy conversion and transformation system (ec and et), energy transfer system, system for storage of the excessive energy and for assurance of the sufficient energy amount (ea). all such constituent parts shall make impact to the common energy efficiency and economic attractiveness. at the same time the need for the cooperation of the professionals from various areas shall arise in the process for implementation of the renewable energy resources, because it includes the climatology, mechanics (aerodynamics, substance resistance, thermodynamics) and in case of the electricity production – electrical engineering. fig. 1 wind energy usage for building heating applying hydraulic system (černeckienė 2015) when the fluid flows through various valves or throttles increase of the fluid temperature is often observed in the hydraulic drives (žiedelis 2009). in the energetics before the operating of the water or steam boiler, the water supply pump is turned on and the water circulates in the closed circle. an increase of water temperature by few degrees can be noticed due to the recirculation during the short interval. in both mentioned cases, a part of the mechanical energy of the fluid flow converted into the heat due to the friction and local hydraulic losses (robert et al. 1996, yeaple 1995). if the heat does not transfer into the environment, fluid temperature increases, what demonstrate the possibility to generate the heat using the hydraulic system. when the energy source of the hydraulic system, driving the hydraulic pump, is the electromotor or the internal–combustion engine, in such case it is not purposeful to generate the heat by the hydraulic system and use it for heating of the building. it is simpler and more efficient use the electric heating units and burn the fuel in the boilers. however, if the energy source of the hydraulic system is the wind got free, the situation will change drastically. the investments to such system can be little, there is a lot of experience in the field of the systems of the electricity generation from wind, and big efficiency of such system, as the heat generator, is possible at that moment (černeckienė and ždankus 2015, ždankus et al. 2016). namely, the hydraulic system, as the heat generator, that pump would be rotated by the movement transferred from the wind rotor, is the object of the experimental studies 65 journal of sustainable architecture and civil engineering 2019/2/25 discussed in this article. possibilities of the hydraulic system characterized as non–complex, collected from the simple elements were investigated experimentally, and the optimum work modes in case of different values of the wind velocity, as well as the possibilities to automatize the system work have been determined. methods the experimental device was designed for simulating and investigating the operation of the hydraulic system driven the wind. the rotational motion of the wind rotor transformed by the reduction gear was simulated by electromotor. three–phase asynchronous, four pole electromotor with the power of 1.5 kw (bevi–4ak2 90l–4b14, cosφ=0.77, ηmotor=0.828) was used in experimental set-up. the fixed rotation frequency of electromotor (nset) meant the simulated rotation frequency of wind rotor for certain wind speed. the fixed nset values correspond to the wind speed between 3.92 m/s and 5.06 m/s taking into account that the wind is harvested with the efficiency 0.45 by the wind rotor with 10 m2 area when the air density is 1.293 kg/m3 (ždankus et al, 2016). the electromotor was calibrated in the special laboratory before starting the experimental investigation. the detailed data of calibration and methodology of computation of the simulated wind speed can be found in our previous study (ždankus et al., 2016). electromotor was mounted by the cover of the oil tank, and its shaft was connected by the rigid coupling to the shaft of the pump of the hydraulic system. hydraulic system assembled of the oil tank, hydraulic pump, supply (pressure) pipe, flow (load) control valve, heat exchanger, and return pipe (fig. 2). hydraulic system contained 20 l of oil (iso viscosity degree 32, ρoil_20°c=867 kg/m 3, νoil_20°c=65·10 -6 m2/s, c=1.67 kj/(kg·k)). the hydraulic gear pump vivolo–x2p5702 (vpump=26.2 cm 3/rot.) was used during investigation. the hydraulic m fset ~ h ea t ex ch an ge r pump was fully submerged into the oil in the rectangle steel oil tank. internal diameter of all pipes was d=20 mm. oil tank, pipes, valve and the heat exchanger were covered by the layer of the heat insulation material (polystyrene foam), in order to minimize the heat losses to the environment. rotation frequency of the shaft of the electromotor was changed by the electric frequency converter mitsubishi electric (fr–d740– 036sc–ec, three–phase, 1.5 kw, 0.2...400 hz). the real rotation frequency of the shaft of the electromotor n was measured by the tachometer testo 465 (tolerance: 0.01 rpm). fig. 2 scheme of the experimental setup (ždankus et al. 2016) load of the hydraulic system – resistance to the flow was changed by decreasing or increasing the permeability of the flow control valve – loading valve. the loss of the liquid mechanical energy in the loading valve showed the potential of the system to generate the heat. valve opening position was changed by the revolutions from the fully opened position αmax=9 revolutions up to the fully closed position α=0 revolutions. the opening degree of the loading valve was calculated by formula: γ=α/αmax. pressure before the loading valve was measured by the pressure sensor nah 25.0 a (0÷25 bar, 4÷20 ma, measurement precision 0.3%), behind the valve – by the pressure sensor nah 2.5 a (0÷2.5 bar, 4÷20 ma, 0.3%). during the experimental investigation the difference of the pressure before (p1) and behind (p2) the loading valve was calculated: δp=p1–p2. it was assumed that liquid mechanical energy loss in the loading valve was equal to generated heat in the valve. thermal energy of generated heat was calculated by the formula: journal of sustainable architecture and civil engineering 2019/2/25 66 pl = δpq = δpnvpump (1) during the experimental investigation, the oil temperature was measured in 4 points: in the oil tank, before the loading valve, before the heat exchanger and behind the heat exchanger. in order to measure the temperature, the thermos-sensors were used (tj4–pt100, precision class ⅓b). indications of the thermos-sensors were read and transferred to the computer by the data storage device data logger pt–104. in order to check the reproducibility and reliability of the results of the experimental investigation, the statistical parameters were calculated for every test series, performed at the same conditions. it was determined that the results of the experimental investigation were quite precise, reliable and reproducible. fig. 3 dependence of the amount of generated thermal energy on the opening degree of the loading valve for nset=12.5, 17.5 and 22.5 hz at t≈20 °c the experiments were carried out at rotation speeds of the shaft of the electromotor: nset=12.5, 17.5 and 22.5 hz. the previous studies are already made with the nset=10.0, 15.0, 20.0 and 25.0 hz, so this study expands the database and increases the accuracy of the experimental investigation. in one case the experimental series were started from the fully opened loading valve γ=1. it was the minimum load of the hydraulic system. next the valve has been fluently closing until γ=0.11. in other case the series started from almost closed (γ=0.11) loading valve and the opening degree of the valve was changed from γ=0.11 to fully opened position γ=1. undistinguished different of the amount of generated thermal energy was noticed. dependence of the amount of thermal energy (pl) generated while liquid passed the valve on the opening degree (γ) of the loading valve is shown in fig. 3. results a few regimes of the hydraulic system work can be noticed for each value of nset: not loaded system (approximately from γ≈1 to γ≈0.8, where: n→nmax, the torque of the shaft: m→mmin), loaded system (from γ≈0.8 to γ≈0.22, there: n→nopt, m→mopt, pl→plmax) and overloaded system (from γ≈0.2 to γ→0, there: n→0, m→mmax, pl→0). the optimal working regime of the hydraulic system (the point of pl=plmax, where γ=γopt, n=nopt, m=mopt) was in the zone of loaded system. 67 journal of sustainable architecture and civil engineering 2019/2/25 the maximum amount of generated thermal energy was equal to pl=369.3 at γopt=0.231 for nset=12.5 hz, pl=537.9 at γopt=0.261 for nset=17.5 hz and pl=722.9 at γopt=0.322 for nset=22.5 hz. dependence of the amount of generated thermal energy (pl) on the rotation frequency of the pump (n) is shown in fig. 4. the optimal values of the rotation frequency of the shaft of the hydraulic pump were equal to nopt=10.3 hz for nset=12.5 hz, nopt=14.5 hz for nset=17.5 hz and nopt=20.2 hz for nset=22.5 hz. fig. 4 dependence of the amount of generated thermal energy on the rotation frequency of the pump at t≈20 °c fig. 5 dependence of the amount of generated thermal energy on the oil temperature for nset=12.5 hz the influence of increase of oil temperature in the range from 20 °c to 50 °c on optimal parameters of the hydraulic system was investigated also. the dependence of the amount of generated thermal energy (pl) on the oil temperature (t) for nset=12.5 hz is shown in fig. 5. journal of sustainable architecture and civil engineering 2019/2/25 68 with increase of oil temperature from t≈20 °c to t≈50 °c the maximum amount of generated thermal energy decreased from plmax=369.3 w to plmax=335.1 w (δpl/plmax=9.3 %), the opening degree of the loading valve was changed from γopt=0.231 to γopt=0.222 and rotation frequency of pump changed from nopt=10.3 hz to nopt=10.0 hz. the dependences of the amount of generated thermal energy (pl) on the oil temperature (t) for nset=17.5 and 22.5 hz are shown in fig. 6 and fig. 7. with increase of t from t≈20 °c to t≈50 °c the plmax decreased from plmax=537.9 w to plmax=524.6 w (δpl/plmax=2.5 %), γopt was changed from γopt=0.261 to γopt=0.256 and nopt changed from nopt=14.5 hz to nopt=14.2 hz for nset=17.5 hz. analogical, plmax decreased from plmax=722.9 w to plmax=669.3 w (δpl/plmax=7.4 %), γopt was changed from γopt=0.322 to γopt=0.289 and nopt changed from nopt=20.2 hz to nopt=19.0 hz for nset=22.5 hz. fig. 6 dependence of the amount of generated thermal energy on the oil temperature for nset=17.5 hz fig. 7 dependence of the amount of generated thermal energy on the oil temperature for nset=22.5 hz 69 journal of sustainable architecture and civil engineering 2019/2/25 the data presented above is necessary for understanding and creating automatic regulation system of the hydraulic unit that uses wind for thermal energy generation. some different schemes of control systems can be proposed (ždankus et al. 2016). the sensor of the wind speed is the main for all schemes for control of the opening position of the loading valve of investigated hydraulic system. the feedback signal to controller can be generated in two cases: from the opening degree of the loading valve or from the pump shaft rotation frequency. the demand of an additional measurement of oil temperature is an object of discussion (ždankus et al. 2016). the losses of generated thermal energy would be 12 w or 3.6 % for nset=12.5 hz and 34.6 w or 5.2 % for nset=22.5 hz without the additional measurement of oil temperature for scheme with feedback from the sensor of opening degree of the loading valve. in other case, the losses of generated thermal energy would be 8.1 w or 2.4 % for nset=12.5 hz and 32.5 w or 4.9 % for nset=22.5 hz without the additional measurement of oil temperature for scheme with feedback from the sensor of pump shaft rotation frequency. conclusions the experiments were carried out at additional different electromotor rotational speeds: 12.5, 17.5 and 22.5 hz. the relationship between the opening degree of the valve and the amount of generated thermal energy was determined. it was noticed that an optimal work regime of system was reached by changing the opening degree of load control valve from 0.1 to 0.33. the maximum amount of generated thermal energy was equal to pl=369.3 w at γopt=0.231 and nopt=10.3 hz for nset=12.5 hz, pl=537.9 w at γopt=0.261 and nopt=14.5 hz for nset=17.5 hz and pl=722.9 w at γopt=0.322 and nopt=20.2 hz for nset=22.5 hz. it was noticed that a change in the kinematic fluid viscosity influences on the amount of generated heat and the optimal value of the opening degree of the loading valve and rotation frequency of the pump. with increase of oil temperature from t≈20 °c to t≈50 °c the maximum amount of generated thermal energy decreased from plmax=369.3 w to plmax=335.1 w (δpl/plmax=9.3 %) for nset=12.5 hz and plmax decreased from plmax=722.9 w to plmax=669.3 w (δpl/plmax=7.4 %), for nset=22.5 hz. the same hydraulic system can generate more thermal power when it is working in lower temperatures, so it suggests combining wind power usage for building heating with the help of heat pumps that accept heat sources with relatively low temperatures. references černeckiene j. usage of the wind energy for heating of the energy-efficient buildings: analysis of possibilities. journal of sustainable architecture and civil engineering, 2015, 10: 58-65. https://doi. org/10.5755/j01.sace.10.1.7479 černeckienė j., ždankus t. vėjo energijos panaudojimo šilumos gamybai, taikant hidraulinę sistemą, tyrimas, energetika, 2015, t61, 1: 32-43. https://doi. org/10.6001/energetika.v61i1.3094 katinas v., markevicius a., perednis e., savickas j. sustainable energy development lithuania‘s way to energy supply security and energetics independence, renew. sustain. energy rev., 2014, 30: 420428. https://doi.org/10.1016/j.rser.2013.10.033 robert j. k. v., street l., watters g. z. elementary fluid mechanics, john wiley & sons, 1996. stigka e. k., paravantis j. a., mihalakakou g. k. social acceptance of renewable energy sources: a review of contingent valuation applications, renew. sustain. energy rev., 2014, 32: 100-106. https://doi. org/10.1016/j.rser.2013.12.026 yeaple f. fluid power design handbook, crc press, 1995. https://doi.org/10.5755/j01.sace.10.1.7479 https://doi.org/10.5755/j01.sace.10.1.7479 https://doi.org/10.6001/energetika.v61i1.3094 https://doi.org/10.6001/energetika.v61i1.3094 https://doi.org/10.1016/j.rser.2013.10.033 https://doi.org/10.1016/j.rser.2013.12.026 https://doi.org/10.1016/j.rser.2013.12.026 journal of sustainable architecture and civil engineering 2019/2/25 70 tadas zdankus professor kaunas university of technology, faculty of civil engineering and architecture main research area fluid mechanics, wind energy conversion, thermal energy storage address studentu st. 48, lt-51367 kaunas, lithuania e-mail: tadas. zdankus@ktu.lt about the authors jurgita cerneckiene lecturer kaunas university of technology, faculty of civil engineering and architecture main research area energy performance in buildings, hvac systems, renewable energy address studentu st. 48, lt-51367 kaunas, lithuania tel.+37061531533 e-mail: jurgita. cerneckiene@ktu.lt leonas greičius master student kaunas university of technology, faculty of civil engineering and architecture main research area wind energy conversion address studentu st. 48, lt-51367 kaunas, lithuania e-mail: leonas. greicius@ktu.edu vidas stanevičius master student kaunas university of technology, faculty of civil engineering and architecture main research area wind energy conversion address studentu st. 48, lt-51367 kaunas, lithuania nerijus bunikis master student kaunas university of technology, faculty of civil engineering and architecture main research area wind energy conversion address studentu st. 48, lt-51367 kaunas, lithuania e-mail: nerijus.bunikis@ ktu.edu ždankus t.; černeckienė j.; jurelionis a.; vaičiūnas j. experimental study of a small scale hydraulic system for mechanical wind energy conversion into heat. sustainability. basel: mdpi ag., 2016, vol. 8, iss. 7, article 637: p. [1-18]. https://doi.org/10.3390/ su8070637 žiedelis s. hidraulinės ir pneumatinės sistemos, kaunas, 2009. https://doi.org/10.3390/su8070637 https://doi.org/10.3390/su8070637 journal of sustainable architecture and civil engineering 2019/2/25 16 *corresponding author: aime.ruus@taltech.ee revitalization of wooden apartments as a tool to deal with shrinkage – case study from valga received 2018/11/18 accepted after revision 2019/03/21 journal of sustainable architecture and civil engineering vol. 2 / no. 25 / 2019 pp. 16-24 doi 10.5755/j01.sace.25.2.22074 revitalization of wooden apartments as a tool to deal with shrinkage – case study from valga jsace 2/25 http://dx.doi.org/10.5755/j01.sace.25.2.22074 aime ruus*, jiri tintera tallinn university of technology, school of technology, tartu college, puiestee 78 51008 tartu, estonia valga is a small shrinking town in south estonia. the study focuses on the possibilities of solving the problems connected with apartment houses by using the disposition of apartments and improving energy efficiency to meet the contemporary standards of living space and getting buildings in public possession. keywords: shrinking cities, housing, urban brownfields, urban decline, post-soviet country, energy performance of buildings. introduction valga is a small shrinking town in south estonia on the border of latvia. valga has lost 33% of its population since 1981 and 28% of the town territory is underused or abandoned. there are 358 apartment buildings in valga and 146 of them have wooden constructions. 22 wooden apartment buildings lie within the heritage conservation area (fig. 1). typical wooden apart kesk 20 fig. 1 schematic plan of valga-valka (tintera et al. 2018) 17 journal of sustainable architecture and civil engineering 2019/2/25 ment buildings have small apartments without bathrooms and with shared toilets in unheated areas. a large share of unused residential and business properties results in a fall in real estate prices. in 2017, the average price of a flat was less than 150 euros per square meter. a low price prevents owners from selling their properties and investment in housing is not lucrative for private sector. the result is the domination of low-quality living premises. six apartment buildings have been demolished in valga during the last three years. the demolished buildings have been replaced with low-cost temporary public green areas. the residents would welcome even more rapid demolition works, however, this is delayed by the complicated ownership relations of the abandoned buildings. still, not all the abandoned buildings should be demolished. the entirety of central valga is a protected heritage site (fig. 1) and it is complicated for demolition works to take place there. also, abandoned buildings in other parts of the city are often of significant historic and architectural value and important elements of the urban landscape. to save at least some of these buildings from complete ruin, new uses must be found for them. there are no high-quality rental flats on the market, even though there is no lack of demand. both public institutions (the city government, the hospital, schools etc.) and entrepreneurs have been complaining about the lack of specialised labour. however, it is difficult to attract specialists to valga because there are no high-quality living spaces on offer. to alleviate this problem that is hindering the city’s development, the public sector – i.e. the local government with the help of the state – must interfere at least temporarily with the free market. from 2017 ministry of economic affairs and communications distributes investment for local governments to support housing development (elamufondi arendamise investeeringutoetus…; kohaliku omavalitsuse üksuse....) the support may be up to 50% of the total project cost and is applied to municipal rental apartments – either new buildings or reconstruction. in this case the building has to be completely owned by the local government. the project does not have to be totally cost effective, otherwise the private sector will deal with the problem. benefit will be a uniform city centre on the area of cultural heritage value enabling the mobility of specialists necessary in the area. of course, the houses must be self-acting during the exploitation later. that is an important aspect for getting support – documents have to be prepared. the paper examines on the case study of kesk 20 apartment housing technical possibilities of building conversion on high quality rental premise. causes and consequences of urban shrinkage the phenomenon of shrinking cities has been recently widely examined by scholars. researchers concentrate on different aspects of urban shrinkage: economic (bogataj, et al. 2016), social (hollander and németh 2011; großmann, et.al. 2015; ročak, et.al. 2016), impacts of shrinking population on land use (kroll and haase 2010; chengbin and ma 2015), and the challenges of urban governance of shrinking cities (wiechmann 2008, rhodes and russo 2013). the term “shrinking city” is used for a city which is losing its population together with its economic importance (reckien and martinez-fenandez 2011; martinez-fernandez et al. 2012; kotilainen et al. 2015; bernt, 2014; sousa and pinho 2015; wiechmann and bontje 2016). the main drivers of shrinkage as such are economic decline with job losses and out-migration, suburbanisation and natural population decline (reckien and martinez-fenandez 2011; martinez-fernandez et al. 2012; großmann et al. 2015; haase, et al. 2016). urban shrinkage results in falling property values, over-dimensioned and underused infrastructure, social problems, out-migration, and waning social life and public spaces (sousa and pinho 2015). two of the most prominent symptoms of shrinkage are housing vacancies and urban brownfields (wiechmann and pallagst 2012; haase et al. 2016). the overcapacity of houses and the outdated state of maintenance cause the decrease of real estate values (elzerman and bontje 2015; bernt, et al. 2017). the private sector is not interested in investing in renovating properties journal of sustainable architecture and civil engineering 2019/2/25 18 or building new apartment buildings. the result is the predominantly low quality of residential premises and the lack of quality apartments. when the quality of life in an apartment building continues deteriorating, those who can do so move out. apartment owners with the lowest income remain in the building, but they cannot afford to pay for maintenance and the building becomes uninhabitable (prada-trigo 2015). the main problem with the owners in valga is that there are a lot of different owners, some of them live abroad. some buildings are in a condition which is not safe for living – the apartments are unusable and their real value is negative (need expenses to demolition or repair). there is very little demand on real estate market at all and no demand for that kind apartments. in that case the owner can gift the apartment to the local government. some apartments are burdened with mortgages. in that case they cannot just gift their property and the local government must find a way how to manage the loans and mortgages. there is (in reality mostly theoretical) possibility that an owner wants to remain an owner and keep the apartment but in that case all the expenses must be covered by them and that part of building is not the subject for support. the local government cannot massively buy the apartments unless the building has architectural or cultural heritage value. some residents have been relocated to other apartments in buildings in a better condition. today buildings must meet energy requirements and offer comfortable indoor environment. if they are on heritage conservation area, it is most important to offer comfortable indoor environment. air tightness is the biggest problem in older wooden buildings. studies carried out in tallinn university of technology (kalamees, et.al. 2011) found that the average values of air leakage rates for wooden apartment buildings was q50=10 m 3/(hm2). minimum and maximum values registered as 3.8 and 22 m3/(hm2) accordingly. in brick and reinforced concrete panel buildings the average air leakage rate was only 4.0 m3/(hm2). according to the minimum requirements for energy performance valid in 2018 (hoone energiatõhususe miinimumnõuded) the average leakage rate of a building envelope may not exceed one cubic metre per hour and per square metre of the building envelope (m3/(hm2) and 1.5 m3/(hm2) for energy calculations. in methodology for calculating the energy performance of buildings valid in 2018 (hoone energiatõhususe arvutamise metoodika) base values (without measured air leakage rates) 3 m3/(hm2) for new buildings and buildings after major renovation, and 6 m3/(hm2) for existing and renovated buildings are given. material and methods the paper looks at the case study of kesk 20 wooden apartment buildings which has the problems described above (fig. 2). the building technical condition is unsatisfactory, and the layouts of apartments inside has morally depreciated. following the used measures: 1) changes in room dispositions, 2) improving energy efficiency, 3) the ownerships constrains have been described. fig. 2 view from north backyard kesk 20 was built in 1917 and is situated in the town centre of valga. most of its structures are made of timber log as wall bearing construction and beams for floor and ceiling. most of the rooms in the building have originally been planned as walk-through rooms (fig. 3). toilets and bathrooms are missing as the building is not connected to water and sewage network. the building used to have ten apartments (5 on the first floor) (fig. 3). the apartments are equipped with stove heating and wood cookers, and the staircases are in unheated area. 19 journal of sustainable architecture and civil engineering 2019/2/25 fig. 3 plan with initial planning of first floor (pai 2015) the building like other similar ones is inefficient in energy use. a log construction (240 mm) without insulation offers approx. value u=0.5 w/(m2k) (evs 908-1:2016). the ceilings and floors in that kind of buildings are often in a condition which is hard to estimate. a ceiling without any insulation or filling has u=1.36 w/(m2k), with porous filler (sawdust, peat, λ=0.116 w/(mk)=0.10 kcal/hm°c, jürgenson, 1949) u=0.38 w/(m2k). floor is a timber floor on dry sand u=0.49 w/(m2k) if to take into account the values of dry sand (λ=0.86 w/(mk)=0.75 kcal/hm°c; jürgenson 1949) and u=0.57 w/(m2k) if to consider only ground λ=2 w/(mk) (evs-en iso 13370:2017). the windows in the building need renovation or replacement. minimum possibility is to repair the windows and improve the heat resistance by adding double glaze package and air tightness. energy simulation for whole building system energy performance was not performed because the idea was to concentrate on the borders and the building itself. total specific heat loss of the building envelope per square metre of heated area σh/aheated w/ (m2k) can be calculated by formula 1 (liginullenergia eluhooned): (1) where: ui is thermal transmittance of element of building envelope w/(m 2k); ai is area of element of building envelope m2; ψj is the thermal transmittance of the linear thermal bridge in w/(mk); lj is the length of the linear thermal bridge in metres; χp is the thermal transmittance of the point thermal bridge in w/k; np is the number of similar point thermal bridges in the building envelope; ρa – air density, 1.2 kg/m 3; ca – specific heat of air, 1.005 kj/(kgk); aheated – heated area m 2; the infiltration air flow rate (m3/s) is calculated by the means of the formula 2: (2) where: q50 is the average air leakage rate in m 3/(h·m2) of the building envelope; a is the area of the building envelope (including floors) in m2; x is the factor which is 35 in the case of a single-storey building; 24 in the case of a two-storey building; 20 in the case of a three to five-storey building. journal of sustainable architecture and civil engineering 2019/2/25 20 the apartments in the building are privately owned and often co-owned which means that the building has dozens of owners. two of the apartments are mortgaged, part of an insolvent estate, some of the owners live abroad. all this requires time-consuming and complicated negotiations to get apartments in public property. results and discussion the paper focuses on the revitalization of apartment buildings lying within the heritage conservation area of valga town. also, the paper presents architectural (fig. 4) and technical solutions for building reconstruction. the reconstruction project (pai 2015) designs 8 apartments (4 on the first floor) (fig. 5). there will be one one-room, two two-roomed and one three-roomed apartment. the staircase will be indoors. the cold toilets will be demolished. the disposition of apartments fig. 4 facade of the building – view from south (pai 2015) fig. 5 plan of the first floor after redesign (pai 2015) 21 journal of sustainable architecture and civil engineering 2019/2/25 will be re-designed to meet the contemporary standards of living space. additional exterior insulation is planned to be added (fig. 6) and most importantly the living environment will be modernized. there will be a comfortable private bathroom in every apartment. fig. 6 cross section of building (a-a on fig. 5, pai 2015) additional exterior insulation (λ=0.33 w/(mk), 150 mm) and wind retarder of 13 mm will make the thermal transmittance u=0.15 w/(m2k) for walls. after the renovation of the floor (slab on ground) with insulation 150 mm xps thermal transmittance will result in u=0.17 w/(m2k), which is not the best suggested value according to energy performance requirements, but the value is improved compared with the initial about three times. the attic floor can be quite easily improved by replacing the insulation between the beams (250 mm) and adding extra insulation of 250 mm, u=0.07 w/(m2k). specific heat loss for building σh, w/k was estimated (table 1). thermal transmittance values for linear thermal bridges are tabulated values from energy efficiency regulation. air tightness is an important component in energy efficiency: range of air leakegae rate q50 from 1.5 to 10m3/(hm2) will change the total specific heat loss of the building envelope 97.3 w/k. if the air leakage rate q50=1.5, specific heat loss caused by infiltration hair leakage=17.2 w/k and in case of q50=10 m 3/(hm2) hair leakage = 114.5 w/k. if base values 3 or 6 m 3/(hm2) are used, 34.3 and 68.7 w/k will be the results of calculations. specific heat loss for the whole building at base value of air leakage 3 m3/(hm2) will be 300.5 w/k (table 1) and delivered energy (valga, balance temperature 15 c, 3617 degree days) and 67.9 kwh/(m2year). variation in air tightness will change the values for specific heat loss from through the building envelope 283.3 to 380.6 w/k and delivered energy values from 64.1 to 86.1 kwh/(m2year). wooden building indicates that there is extra necessity to follow the fire safety requirements. indoor wooden walls will be preserved and covered with gypsum board. wooden or metal-stood partitions will be used instead of demolished brick wall and for new partitions. journal of sustainable architecture and civil engineering 2019/2/25 22 table 4 specific heat loss of the building envelope heat loss through building envelope heat loss through thermal bridges heat loss through air leakage item of envelope g ui, w/(m2 · k) ai, m2 hconduct, w/k thermal bridge ψj, w/(m · k) ij, m hlinear, w/k item number exterior wall 0.15 341.2 51.2 external corner of exterior wall 0.30 26.2 7,9 air-leakage rate q50, m3/(h·m2) 3.0 attic floor 0.07 214.0 15.0 exterior wall – ceiling 0.20 80.0 16.0 avp (building envelope), m2 820.0 slab floor 0.17 214.0 36.4 exterior wall – attic ceiling 0.20 80.0 16.0 number of floors 2.0 door 1.00 4.8 4.8 exterior wall – slab floor 0.30 80.0 24.0 , m 3/s 0.0285 windows 1.60 46.0 73.6 junction window and exterior wall 0.10 145.2 14.5 junction door and exterior wall 0.10 13.2 1.3 exterior wall – interior wall 0.10 65.3 6.5 interior corner of exterior wall –0.20 5.2 –1.0 total hconductivity, w/k 180.9 hlinear thermal bridge, w/k 85.2 hair leakage, w/k 34.3 total specific heat loss of the building envelope σh, w/k 300.5 average thermal transmittance of the envelope σh/avp 0.4 heated area aheated, m 2 383.9 total specific heat loss of the building envelope per square metre of heated area σh/aköetav w/(m2·k) 0.78 the building belongs to fire safety class tp3. fire resistance class for fire protection construction is ei30 and will be achieved with using two layers of gypsum board for wooden or metal-stood partitions. conclusions shrinking population has several outcomes on urban areas. one of them is the prevalence of low quality and underfinanced maintenance housing stock. this results in housing vacancy and abandoned and underused apartment houses. the study shows that buildings can be quite easily revitalized. the main barrier of such revitalization is ownership constrains, not technical issues. public investments in revitalization of wooden apartment building and creation of municipal apartment stock offer citizens high quality living space and helps or enables to stabilize the population of shrinking towns. acknowledgment authors would like to thank alumnus of tartu college of tallinn university of technology tauri pai. references bernt, m. the limits of shrinkage: conceptual pitfalls and alternatives in the discussion of urban population loss. international journal of urban and regional research, 2014; 40 (2): 441-450. https:// doi.org/10.1111/1468-2427.12289 bernt, m., colini, l., & foerste, d. privatization, financialization and state restructuring in eastern germany: the case of am sudpark, international journal of urban and regional research 2017; 41(4): 555-571. https://doi.org/10.1111/1468-2427.12521 23 journal of sustainable architecture and civil engineering 2019/2/25 bogataj d., mcdonnell, d. r., & bogataj, m. management, financing and taxation of housing stock in the shrinking cities of aging societies. int. j. production economics 2016; 181: 2-13. https://doi. org/10.1016/j.ijpe.2016.08.017 chengbin deng, c., & ma, j. viewing urban decay from the sky: a multi-scale analysis of residential vacancy in a shrinking u.s. city. landscape and urban planning 2015; 141: 88-99. https://doi. org/10.1016/j.landurbplan.2015.05.002 elamufondi arendamise investeeringutoetus kohalikele omavalitsustele [investment support for the development of the housing stock for local governments] http://kredex.ee/toetus/kohalikule-omavalitsusele-2/kov1/15.02.2019 elzerman, k., & bontje, m. urban shrinkage in parkstad limburg. european planning studies 2015; 23(1): 87-103. https://doi.org/10.1080/09654313.2 013.820095 evs-en iso 13370:2017. hoonete soojuslik toimivus. soojuslevi pinnasesse. arvutusmeetodid [thermal performance of buildings heat transfer via the ground calculation methods (iso 13370:2017)] eesti standardikeskus. evs 908-1:2016. hoone piirdetarindi soojusjuhtivuse arvutusjuhend. osa 1: välisõhuga kontaktis olev läbipaistmatu piire. [guidance for calculation of thermal transmittance of building envelope. part 1. opaque building envelope in contact with outdoor-air]. eesti standardikeskus. großmann, k., arndt, t., haase, a., rink, d., & steinführer, a. the influence of housing oversupply on residential segregation: exploring the post-socialist city of leipzig. urban geography 2015; 36(4):550-577. https://doi.org/10.1080/02723638.2015.1014672 haase, a., bernt, m., großmann, k., mykhenko, v., & rink d.. varieties of shrinkage in european cities. european urban and regional studies 2016; 23(1): 86102. https://doi.org/10.1177/0969776413481985 hollander, j., & németh, j. the bounds of smart decline: a foundational theory for planning shrinking cities. housing policy debate 2011; 21(3): 349-367. https://doi.org/10.1080/10511482.2011.585164 hoone energiatõhususe arvutamise metoodika [methodology for calculating the energy performance of buildings] https://www.riigiteataja.ee/ akt/119012018007 13.11.2018 hoone energiatõhususe miinimumnõuded [requirements for energy performance], https://www. riigiteataja.ee/akt/119012018006 13.11.18 jürgenson, l. elamuehitus. i, ehitusfüüsika ja -ökonoomika, -materjalid ja põhitarindid “teaduslik kirjandus”; 1949 kalamees, t., arumägi, e., just, a., kallavus, u., mikli, l., thalfeldt, m., klõšeiko, p., agasild, t., liho, e., haug, p., tuurmann, k., liias, r., õiger, k., langeproon, p., orro, o., välja, l., suits, m., kodi, g., ilomets, s., alev, ü., kurik, l. eesti eluasemefondi puidust korterelamute ehitustehniline seisukord ning prognoositav eluiga [technical condition and service life of estonian wooden apartment buildings] tallinn technical university press; 2011. kohaliku omavalitsuse üksuse elamufondi arendamiseks juhtumipõhise investeeringutoetuse andmise tingimused ja kord. [conditions and procedure for granting case-by-case investment support for the development of a local government housing stock] https://www.riigiteataja.ee/ akt/113072018004 15.02.2019 kotilainen, j., eisto, i., & vatanen, e. uncovering mechanisms for resilience: strategies to counter shrinkage in a peripheral city in finland. european planning studies 2015; 23(1): 53-68. https://doi.org /10.1080/09654313.2013.820086 kroll, f., & haase, d.. does demographic change affect land use patterns? a case study from germany. land use policy 2010; 27: 726-737. https://doi. org/10.1016/j.landusepol.2009.10.001 liginullenergia eluhooned. ridaja korterelamud. http://kredex.ee/public/uuringud/liginullenergia_ eluhoonete_tuuplahendused_-_korter-_ja_ridaelamu_juhend.pdf, kredex; 2017 martinez-fernandez, c., audirac, i., fol, s., & cunningham-sabot, e.. shrinking cities: urban challenges of globalization. international journal of urban and regional research 2012; 36(2):213 225. https://doi.org/10.1111/j.1468-2427.2011.01092.x pai, t. valga kesklinna korterelamu rekonstrueerimine munitsipaalkorterelamuks. [reconstruction of apartment house in central valga into a municipal apartment house] master thesis. tallinn university of technology, 2015. prada-trigo, j. local strategies and networks as keys for reversing urban shrinkage: challenges and responses in two medium-size spanish cities. norsk geografisk tidsskrift-norwegian journal of geography 2015; 68(4): 238-247. https://doi.org/10. 1080/00291951.2014.923505 reckien, d., & martinez-fernandez, c. why do cities shrink? european planning studies 2011; 19(8): 1375-1397. https://doi.org/10.1080/09654313.201 1.593333 ročak, m., hospers, g., & reverda, n. searching for social sustainability: the case of the shrinking city of heerlen, the netherlands. sustainlity 2016; 8(4): 1-22. https://doi.org/10.3390/su8040382 journal of sustainable architecture and civil engineering 2019/2/25 24 sousa, s., & pinho, p.). planning for shrinkage: paradox or paradigm. european planning studies 2015; 23(1): 12-32. https://doi.org/10.1080/09654313.20 13.820082 tintera, j., kotval, z., ruus, a., & tohvri, e. inadequacies of heritage protection regulations in an era of shrinking communities: a case study of valga, estonia, european planning studies 2018, 26 (12): 2448-2459. https://doi.org/10.1080/09654313.201 8.1518409 wiechmann, t., & bontje, m. responding to tough times: policy and planning strategies in shrinking cities. european planning studies 2015; 23.1: 1-11. https://doi.org/10.1080/09654313.2013.820077 wiechmann, t. & pallagst, k. m. urban shrinkage in germany and the usa: a comparison of transformation patterns and local strategies. international journal of urban and regional research 2012; 36(2): 261-280. https://doi.org/10.1111/j.14682427.2011.01095.x aime ruus associate professor tallinn university of technology, school of engineering, tartu college main research area building physics, hygrothermal properties of materials address puiestee 78 tartu, 51008 tel. +3726204805 e-mail: aime.ruus@taltech.ee jiri tintera lecturer tallinn university of technology, school of engineering, tartu college main research area revitalization of urban brownfields address puiestee 78 tartu, 51008 tel. +3726204805 e-mail: jiri.tintera@taltech.ee about the authors journal of sustainable architecture and civil engineering 2015/3/12 24 journal of sustainable architecture and civil engineering vol. 3 / no. 12 / 2015 pp. 24-33 doi 10.5755/j01.sace.12.3.12655 © kaunas university of technology received 2015/06/08 accepted after revision 2015/09/29 research on the effect of water draining through vertical drainage systems in the process of soil consolidation jsace 3/12 research on the effect of water draining through vertical drainage systems in the process of soil consolidation corresponding author: fantaziucosmin@yahoo.com http://dx.doi.org/10.5755/j01.sace.12.3.12655 cosmin fantaziu department of transportation infrastructure and foundations,”gheorghe asachi” technical university iasi, faculty of civil engineering and building services, iasi, 700050, romania răzvan chirilă department of transportation infrastructure and foundations,”gheorghe asachi” technical university iasi, faculty of civil engineering and building services, iasi, 700050, romania a saturated soil subjected to a growing total effort will reduce gradually the volume up to excess pore water pressure dissipation, interfering primary consolidation. this process can take a long time and when all excess pressure is dissipated, the soil is considered consolidated. in low permeability soils, from external loading, results in an increase of the normal effort at higher values than the earth preconsolidation pressure, thus having neutral increased pressure followed by a consolidation process where water is expelled from the pores of the soil. the decrease in porosity (soil volume), so produced, is accompanied by a gradual increase of effective pressure and a corresponding decrease in excess pore water pressure. the consolidation process continues until the excess pore water pressure dissipates only complete and upload translates into effective stress. duration of the process depends on the consolidation characteristics of the soil and drainage ways (with how much drainage paths are longer, the longer is the process of consolidation). the purpose of installing vertical drains is to shorten the drainage ways and time needed to dissipate the neutral pressure. the time to dissipate the excess water pressure in the pores (time consolidation) is so short as the inter-distance between the drains is less. keywords: consolidation, drainage, pore pressure, settlement. in order to accelerate the process of settlement (consolidation) and reduce pore water pressure, it is necessary to shorten the length of road drainage through the soil pore water. this can be achieved by placing vertical drains in the ground at calculated distance. the presence of this drainage system enables the pore water overpressure to be eliminated by the nearest horizontal drainage system and free-flowing. by using vertical drains the needed time consolidation process, can usually be reduced from decades to one year or less. execution a network of vertical drains is a means to accelerate the settlements produced in the process of long-term consolidation. another objective of the execution of those works is to improve the conditions for stability of the earth by increasing its shear strength. in areas of high seismic activity, vertical drainage networks can be used to reduce the phenomena of liquefaction. introduction 25 journal of sustainable architecture and civil engineering 2015/3/12 examples of areas where this method is usually used: _ road and railway embankments; _ building and strengthening dykes; _ earthworks made for the construction of the residential, industrial plants, terminals, etc.; _ preload fillings; _ coastal and marine construction; _ land reclamation, ports and airports. the specific functional requirements to each project, underlying geotechnical design vertical drainage. steps to approach fig. 1 representing sand drainage system a vertical drainage project execution, include achieving a working platform, execution a draining mattresses, drawing drainage network model and the installation of drains, followed by loading and monitoring, fig. 1. installing vertical drains may adversely affect the original properties of the earth (eg, decrease shear strength and coefficient of consolidation), so analysis of site conditions reported to drainage method must be very rigorous. due to the excess pressure of the water from the pores created by the load, the ground water is set in motion in the horizontal direction and then is discharged through the drains. an amount of water, generally low, is drained in a vertical direction as a result of one-dimensional consolidation. for the research was used plaxis 2d, which is an advanced calculation using the finite element method for analyzing two-dimensional problems of deformation and stability in geotechnical engineering. plaxis 2d program involves three subprograms called data entry, data calculation program and display the results. performs analysis in plane or axi-symmetry version with 6 or 15 nodes triangular element. in order to describe a ground deformations resulting from changes in the current effort, a mathematical model was assigned to the earth. it governs the relationship stress-strain and is called material model. in plaxis 2d are available a number of materials models. however, this paper will address the mohr-coulomb model only. consolidation analysis is used in plaxis 2d when it is necessary to evaluate the dissipation of excess pore water pressure of saturated clay function of time. here, the important parameter isn’t the type of material drainage but rather permeability parameter specified. is it possible to consolidate with and without additional surcharge. a saturated soil subject to a total effort/strain will reduce gradually the volume up to dissipate excess pore water pressure, interfering primary consolidation. this process can take a long time and when all excess pressure is dissipated, the land is considered consolidated. analysis of the effect of water drainage through vertical drains was achieved by taking into account three assumptions: no drains, with drains placed at 2.0 m between them and sand drains, placed at 2.0 m inter-distance between them. the distance between the two types of drains, was choosen to show the efficiency from the point of view of performance and economic solution. this distance can be modified depending on the needs of drainage, but the 2.0 m between drains is the most common distance applied. the distance between the drains are kept smaller than the thickness of surcharge to reduce radial length of the drainage length. methods journal of sustainable architecture and civil engineering 2015/3/12 26 based on the results obtained in the three hypotheses considered, they were analyzed as graphics, consolidation process characteristic parameters such as displacements, times of consolidation and pore water pressures. modeling was performed on a layered soil profile, with high compressibility clays and incompressible. it was executed a precharge step, serving to highlight the neutral pressure dissipating way and settlements-time curve shape. in table 1 it is presented the type stratifications and geotechnical characteristics, with an increased interest on very compressible soft plastic clay layer. considering the chosen stratification, the greatest interest in analyzing the consolidation process it is represented by the very compressible clay layer. hydrogeological conditions generated by the model (groundwater level at -2.0 m depth) are modified by arranging vertical drains, lines along which the neutral pressure reduced to zero. at the ground surface has represented a drainage layer (mattress), with thickness of 0.5 m, which will ensure water drainage. above this draining layer it is made the embankment of ground filler (preloading equivalent). execution of fill in embankment, will realize in two stages, each stage of each 1.5 m height. contour conditions (the model limits), involves locking the horizontal displacements, while in vertical direction the displacements are free. drainage is prevented from lower limit of the model and table 1 stratification characteristics id name type γ unsat [kn/m3] γ sat [kn/m3] k x [m/day] k y [m/day] ν [-] e ref [kn/m2] c ref [kn/m2] φ [o] 1 dusty clay undrained 16,0 19,9 2,6e-03 1,3e-03 0,35 30000 20 5 2 compressible clay undrained 14,8 19,1 5,2e-04 2,6e-06 0,35 10000 10 5 3 very compressible soft plastic clay undrained 15,0 19,0 1,1e-03 5,5e-04 0,35 3221 8 4 4 dusty clay undrained 15,2 18,4 2,0e-04 1,0e-04 0,35 18000 32 6 5 incompressible clay undrained 18,0 20,0 1,0e-04 1,0e-04 0,35 45000 25 9 6 drainage layer drained 18,0 20,0 8,6430 4,3215 0,30 30000 1 20 7 filling embankment drained 18,0 19,0 8,6430 4,3215 0,30 30000 10 25 fig. 2 the layout analyzed stratifications 27 journal of sustainable architecture and civil engineering 2015/3/12 to the side, open only to the top by drainage mattress. finite element mesh network with integration type 15 knots in 12 gauss points. the model is conducted in three-phase construction, different, to the hypothesis that involves carrying out the drains and the sand columns, in the following order: _ the first stage involves achieving vertical drains or sand columns, and draining sand mattress; _ the second stage involves the execution of the first stage preload by making the first backfill layer of filler; _ the third step involves carrying out the second step of preload, by executing the second filling layer. there is a last phase of computing, which aims to verify the stability of the model according to the conditions and simulation obtained. referring to fig. 3, the stability of the model is secured by a safety factor of 1.62, for vertical drainages, and 1.71, for sand columns. fig. 3 reporting safety factor to the evolution of displacements in 2 cases: a) vertical drainages; b) sand drainages a b journal of sustainable architecture and civil engineering 2015/3/12 28 after running calculation, were obtained the results shown in the following. figure 4 highlights deformed mesh network, the scale deformations is 50:1. the maximum total displacement obtained at the end of the consolidation process, it is 4.8 cm for vertical drainages, and 5.2 cm, for sand columns, otherwise it represents, as shown in figure 5, the maximum settlement to share common ±0.00 m (natural ground surface). the average effective effort is illustrated in figure 6, in the color code. it notes the increase with its depth, but also the inside of the model. the average effective effort is one of compression and has a maximum value of 157.53 kn/m2 for vertical drainages, and 166.49 kn/m2, for sand columns, but the value is found after the -15.00 m depth. figure 7 is represented by the main directions, the total effort, with maximum value of 382.82 kn/m2 for vertical drains, and 401.53 kn/m2, for sand drains. the excess pressure of pore water (neutral pressure) is highlighted in figures 8 during the consolidation process (last step of the pre-load) and 9 at the end of consolidation process. in figure 8, there is an immediate impact by reducing drains along their neutral pressure. figure 9 illustrates the end of the consolidation process, a neutral pressure concentration in the area outside the influence of drains, but the value is very low, about 0.72 kpa for vertical drainages, and 0.69 kpa for sand drains. results fig. 4 the total displacement after consolidation (finite element mesh), for 2 cases fig. 5 the vertical displacement (settlement), representing the contour lines, for 2 cases fig. 6 the average effective effort, code color representation, for 2 cases 29 journal of sustainable architecture and civil engineering 2015/3/12 based on the results, comparative analysis was made in the calculation assumptions, the main parameters consolidation process characteristics such as displacements, consolidation time, effective and total efforts, pore water pressures. improving by the drainage is observed since the analysis of the evolution settlements reported on time, figure 10 maximum land surface settlement in the cases considered, varies between 2 and 4 cm. alura-time settlement curves are following stages of construction, with a considerable increase in the precharge phase followed by slow levels, representative for consolidation phases. the influence is shown by drainage time consumption of settlements, which is 1733 days under free drainage, 616 days when using sand drains and 622 days for vertical drains. fig. 7 the total effort, represented by the main directions, for 2 cases fig. 8 neutral pressure during the consolidation process, color code representation, for 2 cases fig. 9 neutral pressure at the end of consolidation process, color code representation, for 2 cases discussion journal of sustainable architecture and civil engineering 2015/3/12 30 the same phenomenon can be observed in depth at -2.4 m (figure 11) and -8.3 m (figure 12). as regards the time evolution of the lateral displacement at the ground surface, fig. 13 shows a more rapid increase in lateral movements in drained conditions, but it is dictated by rate of consolidation in each case separately. at the end of the consolidation, the maximum lateral displacements in the three hypotheses considered and measured in section a-a (fig. 14) reaches following values: _ without drainage: 23 mm; _ with vertical drains 2m: 16 mm; _ with sand drains: 10 mm. fig. 10 the settlement recorded in the share ± 0,00m fig. 11 settlement at -2.4m depth 31 journal of sustainable architecture and civil engineering 2015/3/12 fig. 12 settlement at -8.3m depth fig. 13 the lateral displacement recorded at the share ± 0,00m, section a-a it can be concluded therefore that the consolidation process of compressible clays, drainage it has influence in reducing vertical and lateral movements. journal of sustainable architecture and civil engineering 2015/3/12 32 fig. 14 horizontal displacements distribution with the depth: a section a-a*; b section b-b* fig. 15 cross sections a-a* and b-b* through terrain profile a b it may outline the following conclusions: _ vertical drainage has an important influence on the time of consumption of settlements. if in the case without the drains, this time is estimated at 1733 days, with the drains arranged at 2 m between axles or sand drains, amortization time is substantially reduced to a minimum of 622 days (1.7 years) if drains spaced at 2m inter distance or 616 days (1,68 years) with sand drains. conclusions 33 journal of sustainable architecture and civil engineering 2015/3/12 _ when using vertical drains, lateral displacements are decreased by over 35%, compared to normal mode without drainage; _ correlation between normal and shear stress in effective values, highlights that the same amount of loading, in drainage conditions, the shear stress values are lower than in the case without drains; _ on excess pressure on the pore water, drainage effects from normal consolidation level at loading aplication, are indicated by a lower value of neutral pressure and by speeding up dissipate velocity of it; _ in the consolidation process, characteristic parameters (settlement, neutral pressure, lateral displacement), varies depending on each other. the acceleration of consolidation process, drainage occurs on the time factor, through rate of neutral dissipation pressure. abdulhafiz omar s. alshenawy determination of the coefficient of consolidation using different methods and study the effect of applied pressure for different types of soils, safar 1428 h, 2007 crawford c. b. interpretation of the consolidation test, journal of the soil mechanics and foundations division, vol. 90, p. 87-102, 1964 dinesh s. v. consolidation of soils, institute of technology tumkur, 2003 indraratna b., chu j. ground improvement – case histories, ed. elsevier, oxford, 2005 indraratna b., rujikiatkamjorn c., sathananthan i. radial consolidation of clay using compressibility indices and varying horizontal permeability, canadian geotechnical journal, 2005 karstunen m. influence of features of natural soft clay on behaviour of embankment, journal of central south university of technology 18 (5), 1667-1676, 2011 lancellotta r. geotechnical engineering, taylor&francis, abingdon, oxon, 2009 maftei g. îmbunătăţirea terenului de fundare sisteme de drenaj [improvement of foundation soil drainage systems], teză de doctorat, universitatea tehnică gh. asachi, iaşi, 2014 mats kahlström plaxis 2d comparison of mohr-coulomb and soft soil material models, luleå university of technology, sweden, 2013 stanciu a., lungu i. fundaţii fizica şi mecanica pământurilor [physics and mechanics of soils], editura tehnică bucureşti, 2006 xiaodi s., xiaoxian s., wenhui d.: element analysys of consolidation of soil under surcharge and vacuum preloading, 2nd international conference on electronic & mechanical engineering and information technology (emeit 2012) wong y.k., joseph comparison of drainage line elements in plaxis 2d and 3d applied in consolidating marine clay deposits, soft soil engineering international conference, sarawak, malaysia, 2013 references cosmin fantaziu phd student ”gheorghe asachi” technical university iasi, department of transportation infrastructure and foundations main research area geotechnical engineering and soil consolidation address 43 d. mangeron, 700050 iasi, romania tel. +074 3890336 e-mail: fantaziucosmin@yahoo.com răzvan chirilă phd student ”gheorghe asachi” technical university iasi, department of transportation infrastructure and foundations main research area geotechnical engineering and soil consolidation address 43 d. mangeron, 700050 iasi, romania tel. +074 2085262 e-mail: razvan_fcs@yahoo.com about the authors journal of sustainable architecture and civil engineering 2016/1/14 80 journal of sustainable architecture and civil engineering vol. 1/ no. 14 / 2016 pp. 80-86 doi 10.5755/j01.sace.14.1.15929 © kaunas university of technology received 2016/05/24 accepted after revision 2016/08/12 development of foam ceramics manufacturing technology jsace 1/14 development of foam ceramics manufacturing technology *corresponding author: aleksandrs.korjakins@rtu.lv http://dx.doi.org/10.5755/j01.sace.14.1.15929 introduction aleksandrs korjakins*, anastasija afanasjeva riga technical university, institute of materials and structures, department of building materials and products, 1 kaļķu street, lv-1658, riga, latvia both dense and porous construction materials are widely used in civil and industrial construction. for example, lightweight concrete, cellular concrete, foam concrete and other types of lightweight concrete are used almost as widely as conventional concrete. however, for the production of walls made of ceramic materials, bricks with dense structure and hollow bricks still are the most popular building materials. lower expenses related to the production of building materials having necessary properties will lead to decreased production costs allowing to increase the production capacity due to the economy of raw materials, other materials and fuel. according to the calculations, today, when the thermal resistance for wall structures has increased 2.5-3 times, having an average density of wall material 900 1100 kg/m3 it is no longer possible to meet the requirements for the thermal resistance of the outer walls 460-520 mm in the climatic conditions of the baltic region. it is necessary either to increase wall thickness or to use more efficient insulation materials which both are not cost-efficient solutions. one of the possible solutions for the given problem is reduction of the average density for the wall material. economic efficiency due to the reduction of average density for the wall material is the following: production capacity of the material decreases, fuel consumption in the production process of blocks or bricks decreases, energy consumption on bricklaying for 1 m2 of the outer wall decreases; less manual work, depending on the wall thickness, heat resistance in walls of the building increases. one of the most ecological and efficient methods is foaming of ceramic slip mass; therefore this technology has been chosen for the given research focusing on the production method of porous ceramics by using foaming of ceramic slip mass. porous ceramics with volume mass ranging from 341 – 799 kg/m3, porosity 25-85 % and compressive strength 0.5 – 1.1 mp was obtained. the following physico-mechanical properties of the specimens were tested: compressive strength, bulk density and water absorption. in the framework of this research porous ceramic material with improved properties has been obtained and production technology of the material has been developed. keywords: foam ceramics, ecological material, insulation material, porous ceramics. the usage of wall and insulation ceramic materials is in a favorable position today. this is mainly related to the fact that the ceramic wall materials have such properties as strength, durability and resistance to the environment, chemicals and influence of micro-organisms. therefore it is easy and convenient to use these materials in the construction process. ceramic wall materials can have moisture-regulating properties thus contributing to healthy microclimate in the building. due to the increasing focus on the energy saving and efficient use of energy coming from various sources in the last years requirements for the thermal performance of buildings has increased. as it is known, conventional ceramic bricks has a relatively high thermal conductivity; therefore, in order to successfully compete in the building material market and to provide to the customers 81 journal of sustainable architecture and civil engineering 2016/1/14 options for building eco houses, manufacturers of ceramic materials have launched new ceramic materials with reduced thermal conductivity. these materials have both advantages and disadvantages compared to the conventional bricks. increased efficiency for the ceramic wall materials can be achieved by reducing the construction costs, labor intensity and mass of the building as well as by increasing their thermal resistance by developing new types of ceramic materials and technologies allowing to that will reduce the material intensity and energy costs. among the justifications for this kind of research activities are increase of fuel and energy costs, the finite nature of high-quality clay resources and increased operation and maintenance requirements for the modern wall materials. one of the most promising trends for the increase of wall ceramic material efficiency is density reduction by creating a porous structure, which is based on the high strength of the baked clay matrix. currently the wall ceramic material density reduction of up to 800 kg/m3 is achieved either by raising product hollowness or by introducing burning-out or melting additives in the composition of ceramic paste. however, from the previous experience it is known that the compressive strength of the above mentioned hollow ceramic materials is up to two times lower compared to the initial products, even by using high qualitymortar. high hollowness of the products, pore sizes and shapes as well as mortars exposure character who acts as a wedge, partly flooding in blocks hollows and causing tensile stresses all are among the reasons of strength reduction in these products. solution for the wall ceramic materials efficiency problem is related to obtaining of the porous structure of foam ceramic materials and optimization of the technological parameters, which allows to obtain high performance products. the goal of present investigation is elaborating technology and mix content for producing foam ceramic. based on the review and analysis of former researches (кролевецкий, 2005, максимова, 2002,, хузагарипов, 2014) the raw materials composition for the foam ceramic productions was developed. bandy clay from the latvian clay deposit “ane” was used as raw material. chemical composition of the clay is presented in table 1, where loi – loss of ignition. plasticizers of the ceramic mass liquid glass and fine soda, foaming agents pb-2000, and the structure stabilizer polypropylene fibers or sawdust. in the first stage it is necessary to create the conditions necessary for the raw clay aggregates dispergation process. it helps to create a stable clay suspension, which is characterized by high fluidity. this is achieved by adding the electrolyte additives. the mechanism of sodium silicate dilution in clay is based on the separation capability with colloidal silicon acid, i.e. polysilicate anion, formation. in the second stage it is necessary to create porous structure of the obtained suspension. the foam and slip mixing takes place in a low speed mixer in order to avoid air release from the foam mass (хузагарипов, 2014). it is known that stable and coagulated clay suspensions are characterized by various sedimentation volumes, because the sediment densities, which are obtained by the stable and coagulated parts of suspension sediments, are significantly differed among themselves. stable (sustainable) suspension settles slowly, and its sediments have dense structure because the falling particles are not sticky and are rolling free one behind the other while packing more densely, taking the minimum potential energy state. coagulated suspension settles quickly and the resultant sediments do not have of dense structure, thereof the falling particles clump together into different randomly created positions, creating granulated aggregates. by analyzing the scientific literature, it has been concluded that the clay materials with high or medium coagulation ability have carbonate impurities calcite and dolomite in the composition. ca2 + and mg2 + ions with good coagulation ability contribute to the clay particle coagulation (кролевецкий, 2005). methods journal of sustainable architecture and civil engineering 2016/1/14 82 table 1 the chemical composition of clay, mass % chemical compound molecular formula % by mass 1 silicon dioxide sio2 50,0 52,0 2 iron (iii) oxide fe2o3 6,0 8,0 3 aluminum oxide al2o3 14,0 16,0 4 titanium dioxide tio2 0,5 1,5 5 calcium oxide cao 8,0 10,0 6 magnesium oxide mgo 4,0 5,0 7 sodium oxide na2o 0,5 1,5 8 potassium oxide k2o 2,5 3,5 9 sulfur trioxide so3 0,0 0,5 10 loi 14,0 16,0 on the stage of ceramic paste preparation, standard 10-% soda and liquid glass solution are used for soaking of raw clay. it has been examined that the best raw material soaking degree is achieved using as an additive liquid glass 0.3-0.4% from the total mass (sodium silicate aqueous solution of silicate module 2.0) and soda 0.2% from the total mass. in this way, the moisture content on the paste preparation stage can be reduced to 56-70%. introducing of calcined soda in the composition provides the strength increase of the plastic mass due to appearing of sodium silicate in the acquisition sage of semi-finished product. in the dehydration process of this product, while it is baked, the water vapour releases contributing to the formation of pneimo-thermal conditions and chipping sintering intensification (максимова, 2002). it is necessary to pay attention to the fact that the viscosity and slips fluidity as well are highly dependent from the water temperature. higher water temperature leads to better fluidity. the optimum value ranges between 40-60 0c (хузагарипов, 2014). regarding the ceramic mass polarization process it should be mentioned that anion active class synthetic surface-active agents were chosen as foaming agents for the experiment, as they are characterized by good stability (sustainability), foam formation and air capturing capacity. physico-chemical properties of the surface-active agents: _ density 1000-1200 kg / m3 at the temperature range of +20 ... + 25 0c; _ hydrogen index (ph) range from 7.0 to 10.0; _ in the solution with foaming agents volume 4%, the foam expansion is at least 7.0; _ foam stability (steadiness)) at least 360. it has been established that the surface-active agent absorption on the particle surface causes its hydro-phobisation. the particles which are coated with the hydrophobic surface-active agent sheath loses contact capabilities with each other. increasing agent content on the particle surface it not only one, but several ion layers can be absorbed. this poly-layer coating causes granulated spatial structure formation, which make impossible partition formation with dense pores. for this reason, the partition formation collapses relatively soon leading to the collapse of the porous structure of the product (кролевецкий, 2005). research of technological processes conducting research it has been concluded that the constant temperature rate drying period results in intense shrinkage of the product. consequently, its heterogeneity leads to appearance of dangerous stresses and cracks. therefore, gradual temperature increase is recommended, in this case from 40 0c to 60 0c. in order to improve the raw product drying properties, e.g. to reduce product shrinkage and other deformations, reinforcing materials, such as sand, cardboard, sawdust, polypropylene fibers and 83 journal of sustainable architecture and civil engineering 2016/1/14 other fibers have been added to the composition of ceramic paste. consequently, there is a huge amount of very fine fibers in the product with a maximum fiber length of 6-8 mm and fiber diameter 6-60 microns. developing of drying process parameters has been followed by the analysis of firing process characteristics. foam ceramic material sintering mechanism is complex; it involves heat and mass exchange as well as physico-chemical processes. it combines physical phenomena determined by the movement of mass and sealing kinetics and chemical processes, which directly related to the heat treatment regime, composition of raw components, gas environment and other factors. clay sintering proceeds under the impact of optimum temperature. the essence of sintering phenomena is that the substance fills the empty space inside the granules and around them. in addition, grain surface area decreases and the contact zone between them increases in this process. the quantity of grains grows, the grid defects decrease and the existing stresses at the material contact zones are removed during the sintering process. however, exceeding the optimum temperature there is a risk of material porosity reduction due to exceeded sintering. the bending strength of the ceramics depends on the firing temperature. the crystallic sio2 inclusions significantly affect the strength of the ceramics. exceeding the optimal firing temperature, strength and density of the ceramics increases and the total thermal resistance product is reduced about two times (матинян, 2011). according to the research about firing process, an optimal firing temperature is 980-1050 °c (черных, 2003). based on previous studies about conducted on the respective clay (see table 1) firing temperature 1000 °c has been selected in a given research. as mentioned above, the foam ceramic material firing process as well as heat and mass transfer processes occur simultaneously, which are considerably encumbered with the phase and physical and chemical transformations related to the technological factors from one side, including physico-chemical and technological properties of raw materials, nature and quality of impurities and additives, the product porosity and the average density value, etc., –and to the external thermal factors from other side, including temperature, gas environment speed and composition, product dimensions, firing oven type, etc. (кролевецкий, 2005). the optimum firing time exposing specimens to the maximum temperature is 2 hours. extended firing time in the maximum temperature does not lead to the improved results. results table 2 experimental raw material compositions raw material, mass % mix nr.1 mix nr.2 mix nr.4 mix nr.5 clay 100 100 100 100 liquid glass 0,3 5 7 7 sodium carbonate 0,2 0,2 0,5 0,5 „pb-2000” 0,05 0,09 0,09 „fairy” 0,09* sawdust 2 2 2 2 the mass forming moisture 60 60 60 60 after summarizing the theoretical material about foam ceramic production technology development, the compositions of raw materials were designed (see. table 2). it contain seven components: clay (100%), forming sustainable structure and strength as the main raw material; liquid glass and soda (5% and 0.2% of the clay mass) acting as electrolytes to increase the fluidity of the clay slips, to facilitate the foam introduction into the slips; foaming agent (0.09% of the clay mass) forming the porous structure of material; polypropylene fi* during foaming process, sugar was added to the solution (0,01 % of the clay mass). journal of sustainable architecture and civil engineering 2016/1/14 84 bers and sawdust (2% of the clay mass) as structural stabilizers reducing drying shrinkage; and forming moisture water (60% of the clay mass) intended for softening of raw material, dilution of electrolytes and for foaming of foaming agents. the first two experimental groups of specimens were dried for 2 hours in natural conditions without additional loading pressure to reduce drying shrinkage and then for 24 hours in the oven at 50 °c. the third and fourth groups of specimens were not dried in natural conditions were placed immediately after the molding in the drying oven at temperature of 100 0c for 24 hours instead. the artificial drying is used to completely remove the excess water from foam ceramic mass and to avoid shrinkage cracks during the firing process. during the drying the sample size changes were observed shrinkage in the horizontal direction and swelling in the vertical direction. the main problem faced in process of conducting experiments using the foam method is its collapse without being able to create a sufficiently persistent frame, which should resist the force fig. 1 the obtained foam ceramic material firing cooling mode sawdust 2 2 2 2 the mass forming moisture 60 60 60 60 * during foaming process, sugar was added to the solution (0,01 % of the clay mass). the first two experimental groups of specimens were dried for 2 hours in natural conditions without additional loading pressure to reduce drying shrinkage and then for 24 hours in the oven at 50 °c. the third and fourth groups of specimens were not dried in natural conditions were placed immediately after the molding in the drying oven at temperature of 100 0c for 24 hours instead. the artificial drying is used to completely remove the excess water from foam ceramic mass and to avoid shrinkage cracks during the firing process. during the drying the sample size changes were observed shrinkage in the horizontal direction and swelling in the vertical direction. the main problem faced in process of conducting experiments using the foam method is its collapse without being able to create a sufficiently persistent frame, which should resist the force of gravity. this could be improved in two ways; firstly, based on the ph value, when then anhydrous is added, secondly, considering the temperature increase. to resolve the problems, thermal swelling agent can be used which will prevent foam collapse. according to the developed firing mode pore ceramic product samples were kept at the temperature range from 0 to 150 °c for 30 minutes to ensure that there is no excess water is left in the samples to facilitate the cracks. in the range of 150800 °c temperature increase rate was 5 °c/min or 130 min in total, and in the range of 800-1000 °c 2 °c/min or 145 min in total. the samples were held at the maximum temperature 1000 °c for one hour, so that all samples were fully fired. then it was followed by the cooling process with gradual temperature decrease. the sample firing cooling process curve (mode) is shown in fig.1. fig. 1. the obtained foam ceramic material firing cooling mode the sample of material, which was examined under a microscope, has fine porosity with average pore diameters being 0.70-1.52 mm. there are also some pores with smaller diameter or larger diameter. pores have regular round shape (see fig. 2.). the walls among pores are about 0.36-0.70 mm thick. picture of the obtained material in macro mode with a pronounced fine porosity is included in fig. 3. analysis of the research results shows that the obtained ceramic materials whose raw material is characterized by polymineral composition has both solid-phase and liquid-phase sintering processes. 0 500 1000 1500 te m pe ra tu re , 0 c time, min the samples roasting cooling regime sawdust 2 2 2 2 the mass forming moisture 60 60 60 60 * during foaming process, sugar was added to the solution (0,01 % of the clay mass). the first two experimental groups of specimens were dried for 2 hours in natural conditions without additional loading pressure to reduce drying shrinkage and then for 24 hours in the oven at 50 °c. the third and fourth groups of specimens were not dried in natural conditions were placed immediately after the molding in the drying oven at temperature of 100 0c for 24 hours instead. the artificial drying is used to completely remove the excess water from foam ceramic mass and to avoid shrinkage cracks during the firing process. during the drying the sample size changes were observed shrinkage in the horizontal direction and swelling in the vertical direction. the main problem faced in process of conducting experiments using the foam method is its collapse without being able to create a sufficiently persistent frame, which should resist the force of gravity. this could be improved in two ways; firstly, based on the ph value, when then anhydrous is added, secondly, considering the temperature increase. to resolve the problems, thermal swelling agent can be used which will prevent foam collapse. according to the developed firing mode pore ceramic product samples were kept at the temperature range from 0 to 150 °c for 30 minutes to ensure that there is no excess water is left in the samples to facilitate the cracks. in the range of 150800 °c temperature increase rate was 5 °c/min or 130 min in total, and in the range of 800-1000 °c 2 °c/min or 145 min in total. the samples were held at the maximum temperature 1000 °c for one hour, so that all samples were fully fired. then it was followed by the cooling process with gradual temperature decrease. the sample firing cooling process curve (mode) is shown in fig.1. fig. 1. the obtained foam ceramic material firing cooling mode the sample of material, which was examined under a microscope, has fine porosity with average pore diameters being 0.70-1.52 mm. there are also some pores with smaller diameter or larger diameter. pores have regular round shape (see fig. 2.). the walls among pores are about 0.36-0.70 mm thick. picture of the obtained material in macro mode with a pronounced fine porosity is included in fig. 3. analysis of the research results shows that the obtained ceramic materials whose raw material is characterized by polymineral composition has both solid-phase and liquid-phase sintering processes. 0 500 1000 1500 te m pe ra tu re , 0 c time, min the samples roasting cooling regime fig. 2. the obtained foam ceramic material pore arrangement under the microscope. magnification x4. microscope lens: 4 / 0.1 _ 160 / 00.17. fig.3. the foam ceramic material. photo in macro mode the water absorption has been performed as passive absorption and measured as relation between weight of absorbed water and weight of dry specimen. the sample density and water absorption ratios are presented in fig. 4. fig. 4. the sample density and water absorption in graphical interpretation fig. 5. destructive load and sample water absorption in graphical interpretation there is no observed strong correlation between water absorption and porosity of porous ceramic due to differences in the structures of pores. the opened pores have been observed for materials with high density. as results, the water absorption is higher for this specimens and reaches 86%. more light specimens with higher porosity have less water absorption due to closed structure of pores. formation the closed structure of pores in light materials may be explained by physico-chemical properties and their interaction of clay and additives applied for porization of clay. compressive strength was defined in accordance with lvs 358:2003. compressive strength test results are summarized in fig. 5. the average strength of the samples varies between 0.3-1.1 mpa for densities 341 – 799 kg/m3. obtained results are lower in comparison with reached strength by other researchers 3.1-9.3 mpa for densities 450-850 kg/m3 350 450 550 650 750 850 10 30 50 70 90 d en si ty o f t he s am pl e ρ, kg /m 3 water absorbtion, % 0 50 100 0.1 0.6 1.1 1.6 w at er a bs or bt io n, % destructive load r, mpa of gravity. this could be improved in two ways; firstly, based on the ph value, when then anhydrous is added, secondly, considering the temperature increase. to resolve the problems, thermal swelling agent can be used which will prevent foam collapse. according to the developed firing mode pore ceramic product samples were kept at the temperature range from 0 to 150 °c for 30 minutes to ensure that there is no excess water is left in the samples to facilitate the cracks. in the range of 150-800 °c temperature increase rate was 5 °c/min or 130 min in total, and in the range of 800-1000 °c 2 °c/ min or 145 min in total. the samples were held at the maximum temperature 1000 °c for one hour, so that all samples were fully fired. then it was followed by the cooling process with gradual temperature decrease. the sample firing cooling process curve (mode) is shown in fig.1. the sample of material, which was examined under a microscope, has fine porosity with average pore diameters being 0.70-1.52 mm. there are also some pores with smaller diameter or larger diameter. pores have regular round shape (see fig. 2). the walls among pores are about 0.36-0.70 mm thick. picture of the obtained material in macro mode with a pronounced fine porosity is included in fig. 3. analysis of the research results shows that the obtained ceramic materials whose raw material is characterized by poly-mineral composition has both solid-phase and liquid-phase sintering processes. fig. 2 the obtained foam ceramic material pore arrangement under the microscope. magnification x4. microscope lens: 4 / 0.1 _ 160 / 00.17 fig. 3 the foam ceramic material. photo in macro mode 85 journal of sustainable architecture and civil engineering 2016/1/14 the water absorption has been performed as passive absorption and measured as relation between weight of absorbed water and weight of dry specimen. the sample density and water absorption ratios are presented in fig. 4. there is no observed strong correlation between water absorption and porosity of porous ceramic due to differences in the structures of pores. the opened pores have been observed for materials with high density. as results, the water absorption is higher for this specimens and reaches 86%. more light specimens with higher porosity have less water absorption due to closed structure of pores. formation the closed structure of pores in light materials may be explained by physico-chemical properties and their interaction of clay and additives applied for porization of clay. compressive strength was defined in accordance with lvs 358:2003. compressive strength test results are summarized in fig. 5. the average strength of the samples varies between 0.3-1.1 mpa for densities 341 – 799 kg/m3. obtained results are lower in comparison with reached strength by other researchers 3.1-9.3 mpa for densities fig. 4 the sample density and water absorption in graphical interpretation fig. 5 destructive load and sample water absorption in graphical interpretation fig. 2. the obtained foam ceramic material pore arrangement under the microscope. magnification x4. microscope lens: 4 / 0.1 _ 160 / 00.17. fig.3. the foam ceramic material. photo in macro mode the water absorption has been performed as passive absorption and measured as relation between weight of absorbed water and weight of dry specimen. the sample density and water absorption ratios are presented in fig. 4. fig. 4. the sample density and water absorption in graphical interpretation fig. 5. destructive load and sample water absorption in graphical interpretation there is no observed strong correlation between water absorption and porosity of porous ceramic due to differences in the structures of pores. the opened pores have been observed for materials with high density. as results, the water absorption is higher for this specimens and reaches 86%. more light specimens with higher porosity have less water absorption due to closed structure of pores. formation the closed structure of pores in light materials may be explained by physico-chemical properties and their interaction of clay and additives applied for porization of clay. compressive strength was defined in accordance with lvs 358:2003. compressive strength test results are summarized in fig. 5. the average strength of the samples varies between 0.3-1.1 mpa for densities 341 – 799 kg/m3. obtained results are lower in comparison with reached strength by other researchers 3.1-9.3 mpa for densities 450-850 kg/m3 350 450 550 650 750 850 10 30 50 70 90 d en si ty o f t he s am pl e ρ, kg /m 3 water absorbtion, % 0 50 100 0.1 0.6 1.1 1.6 w at er a bs or bt io n, % destructive load r, mpa fig. 2. the obtained foam ceramic material pore arrangement under the microscope. magnification x4. microscope lens: 4 / 0.1 _ 160 / 00.17. fig.3. the foam ceramic material. photo in macro mode the water absorption has been performed as passive absorption and measured as relation between weight of absorbed water and weight of dry specimen. the sample density and water absorption ratios are presented in fig. 4. fig. 4. the sample density and water absorption in graphical interpretation fig. 5. destructive load and sample water absorption in graphical interpretation there is no observed strong correlation between water absorption and porosity of porous ceramic due to differences in the structures of pores. the opened pores have been observed for materials with high density. as results, the water absorption is higher for this specimens and reaches 86%. more light specimens with higher porosity have less water absorption due to closed structure of pores. formation the closed structure of pores in light materials may be explained by physico-chemical properties and their interaction of clay and additives applied for porization of clay. compressive strength was defined in accordance with lvs 358:2003. compressive strength test results are summarized in fig. 5. the average strength of the samples varies between 0.3-1.1 mpa for densities 341 – 799 kg/m3. obtained results are lower in comparison with reached strength by other researchers 3.1-9.3 mpa for densities 450-850 kg/m3 350 450 550 650 750 850 10 30 50 70 90 d en si ty o f t he s am pl e ρ, kg /m 3 water absorbtion, % 0 50 100 0.1 0.6 1.1 1.6 w at er a bs or bt io n, % destructive load r, mpa 1 2 3 4 destructive load, mpa 1.09 0.94 0.54 0.32 liquid glass content in, % 0.3 5 7 7 0 2 4 6 8 0 0.2 0.4 0.6 0.8 1 1.2 450-850 kg/m3 (кролевецкий, 2005). low strength may be explained by lacks in the technology of drying and firing, that have to be developed. water absorption of obtained materials is in the range 13-86%, that is very close to results of other researchers 29-71% (кролевецкий, 2005). increase of the liquid glass amount from 0.3 % of the total mass to 7 % improves fluidity and structural homogeneity of the mass but the third and fourth group of specimens with increased content of the liquid glass have lower strength, than the first and second group of the specimens (see fig. 6); fig. 6 destructive load and compositions of specimens with liquid glass in graphical interpretation in the framework of this research foam ceramic material production technology was designed. after conducting research on the production technological parameters as well as physico-chemical and physico-mechanical properties of raw materials, it has been concluded that clay materials tend to have coagulant structure allowing to develop sustainable raw product structure of foam ceramic material without plaster additives as well as to reduce time of the mass moulding process to 2-3 hours. the compositions of ceramic mass with various content of the liquid glass and surfactants have been developed, their main features have been assessed and optimal parameters for preparation, porization, drying and firing processes have been set. by varying the content of foaming agents it is possible to obtain products with an average density of 341 – 799 kg/m3 and strength limits in the range of 0.3-1.1 mpa. conclusions journal of sustainable architecture and civil engineering 2016/1/14 86 reduction of the foam ceramic material density by increasing the surfactant content is possible up to a certain limit. excess surfactant content (≥ 0.05 % of the total mass) does not give the expected results, and it is economically unjustified. foam ceramic material drying and firing processes are characterized by a number of features related to the production method, physico-chemical and technological properties of the clay raw materials and additives, nature of porous structure, etc. it has been concluded that the strength indicators of specimen groups, which were dried at the temperature 50 0c, reached higher values (0.9-1.1 mpa) when the internal structure of the material slowly releasing its free water has been stabilized leading to lower shrinkage compared to the specimen groups, which were dried at the temperature of 100 0c (0.3-0.6 mpa) characterised by rapid evaporation of free water, shrinking of the internal structure and micro-cracking. as a result, drying shrinkage of all specimens does not exceed 20%. in general, the obtained results are evaluated as positive. the direction is considered to be prospective and economically justifiable. the financial support of the latvian council of science, project nr.z12.0412 is acknowledged. acknow ledgment ghazi al-marahleh production of light weight ceramics teils from local materials. american journal of applied sciences. 2005; 2 (4): 778-783. http://dx.doi. org/10.3844/ajassp.2005.778.783 кролевецкий д.в. пенокерамические стеновые и теплоизоляционные изделия на основе легкоплавких глин. диссертация на соискание ученой степени кандидата технических наук. москва: 2005. максимова с.м. стеновые керамические материалы пониженной средней плотности на основе высококальциевой золы и микрокремнезема. автореферат диссертации на соискание ученой степени кандидата технических наук. томск: 2002. матинян с.с. теплоизоляционные материалы на основе отходов стекольного производства. диссертация на соискание ученой степени кандидата технических наук. иваново: 2011. хузагарипов а.г., габидуллин м.г. отработка технологических приемов при производстве пенокерамики на основы сырьевой базы республики татарстан [working out of processing methods in the production of ceramic foam on the bases of the raw material base of the republic of tatarstan]. известия кгасу, 2007; 1(7): 67-70. черных в., маштаков а., галаган к., шестакова е. строительные изделия с применением глинистого сырья [building products using raw clay]. строительные материалы, 2003; 12: 46-47. lvs 358:2003, masonry units methods for determination of ultimate compressive and bending strength, 2003. latvia aleksandrs korjakins professor riga technical university, faculty of civil engineering, institute of materials and structures, head of department of building materials and products main research area ceramic, lightweight concrete, uhpc, insulation materials address 1 kalku street, lv-1658, riga, latvia cell +371 26422442 e-mail: aleksandrs.korjakins@rtu.lv anastasija afanasjeva ph. d. student riga technical university, faculty of civil engineering, institute of materials and structures, department of building materials and products main research area clay porous ceramic address 1 kalku street, lv-1658, riga, latvia tel.: 26002589 e-mail: anastasija.afanasjeva@rtu.lv references about the authors 47 journal of sustainable architecture and civil engineering 2020/1/26 *corresponding author: b.gorgiladze@gtu.ge adaption of buildings shape with renewable energy consumption received 2019/06/22 accepted after revision 2019/11/21 journal of sustainable architecture and civil engineering vol. 1 / no. 26 / 2020 pp. 47-52 doi 10.5755/j01.sace.26.1.23080 adaption of buildings shape with renewable energy consumption jsace 1/26 http://dx.doi.org/10.5755/j01.sace.26.1.23080 badri gorgiladze* laboratory of architectural physics and multimedia design at faculty of architecture, urban planning and design of georgian technical university, 77 kostava str., 0160, tbilisi, georgia gocha mikiashvili international design school of georgian technical university, 77 kostava str., 0160, tbilisi, georgia nino imnadze faculty of architecture, urban planning and design of georgian technical university, 77 kostava str., 0160, tbilisi, georgia the presented research aims to advance green energy consumption by integration of energy conversion schemes into buildings, as an inherent part of architectural construction. realization of such tasks implies variation and adjustment of external shapes of buildings. particular solutions depend on the chosen types of renewable energy sources, geographic location, and environmental conditions. the novelty of suggested solutions is based on the principle of preliminary crowding of solar radiation, but against known analogs concentration of light by mirrors here used not for achieving of high amplitudes, but for diurnal equalization of an energy conversion process. autodesk software products have been used for adjustment of conceptual schemes, including the models of buildings shaped as right circular, or elliptic, cylindrical reflectors. the basic evaluation carried out for the north temperate zone. obtained results confirm that integration of local energy converters and appropriate modification of external shapes of buildings is more flexible and efficient than the application of centralized solar plants, because of their inexpensiveness and harmonization of beauty and energy efficiency. application of static self-regulation of illuminance provides a high level of reliability and simplicity in exploitation. suggested principle provides stepwise promotion of sustainability because it implies not only a passive economy of energy dissipation but also the equipment of architectural objects with inherent modules for active generation of renewable energy. further development of such energy sourcing schemes is related also with the advancement of general safety (lowering of hazardous voltage) by the transition from common electrical grid to adaptive local systems. keywords: sustainable, renewable, photovoltaic, energy, efficiency. main novelty of suggested approach is the task to integrate energy conversion modules into general architectural concept, transform them as an inherent part of green building, instead of their usage as outboard appliance on roofs and/or walls. one of kernel point for realization of such tasks implies variation and adjustment of external shapes of buildings. certain solution depends on chosen types of renewable energy sources and geographic location, including environmental conditions. novelty of suggested schemes is based on the principle of preliminary crowding of solar radiation (and/or wind flow), but against known analogues concentration of light by mirrors here used not for achieving of high amplitudes, but for diurnal equalization of energy generation. introduction journal of sustainable architecture and civil engineering 2020/1/26 48 below we try to argue flexibility and efficiency of local application of renewable resources against traditional usage of centralized solar plants and/or wind stations. however, to understand the essence of this idea, it is better to discuss the tasks separately, accordingly to the nature of appropriate physical processes. fig. 2 current–voltage dependence from temperature for multi-crystalline typical silicon solar cell the advancement of semiconductor technologies used in solar cells caused a new reality (valancius et al. 2018) when an electric energy supplying can be provided locally. prices of photovoltaic panels, used with this purpose, decreased significantly. moreover, the full sets of energy blocks from “tesla” company also include the components for energy accumulation and possibility of their conjugation with standard power networks (https://www.tesla.com/en_eu/energy). obviously, these innovative and quite actual technologies already have found reflection in modern architecture, and the best example is the center for music and performing arts “la seine musicale”, built in western suburb of paris. project designed by architectural team of shigeru ban and jean de gastines (shigeru ban 2017). the creative idea of architectural intent is related to the theme of “solar wind”. structure reminding “fantastic ship” (alike sydney opera house) built directly on an island in seine river. the huge construction (mounting solar panels) looks like wind-blown sail and rotates around the central eggshaped body of the “ship” (fig. 1). auto regulation of the angle between panels and sun’s rays (azimuth) performed by the rotation of this construction on the rails, around the central axis. at noon, when the solar radiation fig. 1 musical center on seine river 2 novelty of suggested schemes is based on the principle of preliminary crowding of solar radiation (and/or wind flow), but against known analogues concentration of light by mirrors here used not for achieving of high amplitudes, but for diurnal equalization of energy generation. below we try to argue flexibility and efficiency of local application of renewable resources against traditional usage of centralized solar plants and/or wind stations. however, to understand the essence of this idea, it is better to discuss the tasks separately, accordingly to the nature of appropriate physical processes. 2. solar radiation the advancement of semiconductor technologies used in solar cells caused a new reality (valancius et al. 2018) when an electric energy supplying can be provided locally. prices of photovoltaic panels, used with this purpose, decreased significantly. moreover, the full sets of energy blocks from "tesla" company also include the components for energy accumulation and possibility of their conjugation with standard power networks (https://www.tesla.com/en_eu/energy). obviously, these innovative and quite actual technologies already have found reflection in modern architecture, and the best example is the center for music and performing arts “la seine musicale”, built in western suburb of paris. project designed by architectural team of shigeru ban and jean de gastines (shigeru ban 2017). the creative idea of architectural intent is related to the theme of "solar wind". structure reminding "fantastic ship" (alike sydney opera house) built directly on an island in seine river. the huge construction (mounting solar panels) looks like wind-blown sail and rotates around the central egg-shaped body of the “ship” (fig. 1). auto regulation of the angle between panels and sun's rays (azimuth) performed by the rotation of this construction on the rails, around the central axis. at noon, when the sun reaches the highest point (altitude), the main workload comes on the panels adjacent to "tip" (they have less surface area) while in the morning and evening, mainly contribute the wider lower sectors. in general, the concentration of sun rays is important for solar energy application, as it performed in so called solar furnaces (trombe et al. 1973), e.g. in france, or in uzbekistan, but the crowding of solar radiation is not used for photovoltaic convertors, because their efficiency sharply falls (see fig. 2) during overheating (krauter and ochs 2004). generally solar panels have many specific features and for achieving of best results they should be taken into account, e.g. in a hot climate it is necessary to additionally install active coolers for this reason. fig. 1. musical center on seine river. 3 the principle proposed in the present paper provides the static self-regulation of receiver orientation against direction of sun rays by mirroring and choosing of building shapes. however, unlike the solar furnaces, the concentration of rays here performed just for equalizing of diurnal illuminance, not for reaching its high amplitude. such statement of a task does not require special quality of reflective surfaces and their exact positioning. this way incomparably reduces the final costs. nowadays glass, as a material, is widely used in construction industry, because of its aesthetics and useful physical properties. its surface is inert against harmful environmental factors. it is transparent in a visible area and so-called double-glazing provides with best insulation. glass also has moreover resources. expansion of glass constructions in modern cities causes abundance of scattered light background, what also can be used for different purposes. variations of glass-faced building shapes became a most popular in modern architecture. one of the core points is to gain maximal technical effectiveness along with the aesthetic beauty. we assume that more resource lies in the reflective properties of a glass surface. fig. 3 shows vertically arranged multiple double glazing units' chain along the elliptical contour, which creates reflective surfaces on one horizontal layer (floor). such reflective “belt” of windows in horizontal section has the shape of a sliced claw, diagonal of which is parallel to east-west geographic direction. inner mirrors (constitute elliptic cylindrical collector) directed towards the south (in models destined for north temperate zone). during daylight, when the azimuth of the sun is changed, only several part of solar rays (reflected from a few mirrors) fall onto one receiver mounted on narrow tower located in elliptic foci (doesn't shown on this drawing). compensation of the height of the sun (as well as the seasonal changes) self-regulated by daytime alternations of "active layers" (floors). it means that during daylight, at any moment of time, sunrays fall onto one receiver only from a few mirrors. correction of mirrors arrangement obeys the principle to supply the solar panels with maximal illuminance in the morning and the evening. at noon contrary radiation flow on cells decreases, due to increase of an incident angle. thus panels are optimally lightened and protected from overheating. efficiency of this scheme lie in the following: instead of installation of many expensive solar panels, we use the usual glass surface of a building (windows and/or other glazing superficial segments) as a reflector directing light on smaller amount of panels. we do not add any material or coating, we just planning beforehand azimuthal orientation of windows (they remain vertical). so additional cost does not arise. fig. 2 current–voltage dependence from temperature for multi-crystalline typical silicon solar cell. fig. 3. the mirror’s belt along one storey. sun reaches the highest point (altitude), the main workload comes on the panels adjacent to “tip” (they have less surface area) while in the morning and evening, mainly contribute the wider lower sectors. in general, the concentration of sun rays is important for solar energy application, as it performed in so called solar furnaces (trombe et al. 1973), e.g. in france, or in uzbekistan, but the crowding of solar radiation is not used for photovoltaic convertors, because their efficiency sharply falls (see fig. 2) during overheating (krauter and ochs 2004). generally solar panels have many specific features and for achieving of best results they should be taken into account, e.g. in a hot climate it is necessary to additionally install active coolers for this reason. the principle proposed in the present paper provides the static self-regulation of receiver orientation against direction of sun rays by mirroring and choosing of building shapes. however, unlike the solar furnaces, the concentration of rays here performed just for equalizing of diurnal illuminance, not for reaching its high amplitude. such statement of a task does not require special qual49 journal of sustainable architecture and civil engineering 2020/1/26 fig. 3 the mirror’s belt along one storey ity of reflective surfaces and their exact positioning. this way incomparably reduces the final costs. nowadays glass, as a material, is widely used in construction industry, because of its aesthetics and useful physical properties. its surface is inert against harmful environmental factors. it is transparent in a visible area and so-called double-glazing provides with best insulation. glass also has moreover resources. expansion of glass constructions in modern cities causes abundance of scattered light background, what also can be used for different purposes. variations of glass-faced building shapes became a most popular in modern architecture. one of the core points is to gain maximal technical effectiveness along with the aesthetic beauty. we assume that more resource lies in the reflective properties of a glass surface. fig. 3 shows vertically arranged multiple double glazing units’ chain along the elliptical contour, which creates reflective surfaces on one horizontal layer (floor). such reflective “belt” of windows in horizontal section has the shape of a sliced claw, diagonal of which is parallel to east-west geographic direction. inner mirrors (constitute elliptic cylindrical collector) directed towards the south (in models destined for north temperate zone). 3 the principle proposed in the present paper provides the static self-regulation of receiver orientation against direction of sun rays by mirroring and choosing of building shapes. however, unlike the solar furnaces, the concentration of rays here performed just for equalizing of diurnal illuminance, not for reaching its high amplitude. such statement of a task does not require special quality of reflective surfaces and their exact positioning. this way incomparably reduces the final costs. nowadays glass, as a material, is widely used in construction industry, because of its aesthetics and useful physical properties. its surface is inert against harmful environmental factors. it is transparent in a visible area and so-called double-glazing provides with best insulation. glass also has moreover resources. expansion of glass constructions in modern cities causes abundance of scattered light background, what also can be used for different purposes. variations of glass-faced building shapes became a most popular in modern architecture. one of the core points is to gain maximal technical effectiveness along with the aesthetic beauty. we assume that more resource lies in the reflective properties of a glass surface. fig. 3 shows vertically arranged multiple double glazing units' chain along the elliptical contour, which creates reflective surfaces on one horizontal layer (floor). such reflective “belt” of windows in horizontal section has the shape of a sliced claw, diagonal of which is parallel to east-west geographic direction. inner mirrors (constitute elliptic cylindrical collector) directed towards the south (in models destined for north temperate zone). during daylight, when the azimuth of the sun is changed, only several part of solar rays (reflected from a few mirrors) fall onto one receiver mounted on narrow tower located in elliptic foci (doesn't shown on this drawing). compensation of the height of the sun (as well as the seasonal changes) self-regulated by daytime alternations of "active layers" (floors). it means that during daylight, at any moment of time, sunrays fall onto one receiver only from a few mirrors. correction of mirrors arrangement obeys the principle to supply the solar panels with maximal illuminance in the morning and the evening. at noon contrary radiation flow on cells decreases, due to increase of an incident angle. thus panels are optimally lightened and protected from overheating. efficiency of this scheme lie in the following: instead of installation of many expensive solar panels, we use the usual glass surface of a building (windows and/or other glazing superficial segments) as a reflector directing light on smaller amount of panels. we do not add any material or coating, we just planning beforehand azimuthal orientation of windows (they remain vertical). so additional cost does not arise. fig. 2 current–voltage dependence from temperature for multi-crystalline typical silicon solar cell. fig. 3. the mirror’s belt along one storey. during daylight, when the azimuth of the sun is changed, only several part of solar rays (reflected from a few mirrors) fall onto one receiver mounted on narrow tower located in elliptic foci (doesn’t shown on this drawing). compensation of the height of the sun (as well as the seasonal changes) self-regulated by daytime alternations of “active layers” (floors). it means that during daylight, at any moment of time, sunrays fall onto one receiver only from a few mirrors. correction of mirrors arrangement obeys the principle to supply the solar panels with maximal illuminance in the morning and the evening. at noon contrary radiation flow on cells decreases, due to increase of an incident angle. thus panels are optimally lightened and protected from overheating. efficiency of this scheme lie in the following: instead of installation of many expensive solar panels, we use the usual glass surface of a building (windows and/or other glazing superficial segments) as a reflector directing light on smaller amount of panels. we do not add any material or coating, we just planning beforehand azimuthal orientation of windows (they remain vertical). so additional cost does not arise. thus, the number of solar panels are optimized and mounted on separately arranged tower. accumulators and other accessories also placed in the same tower, at a distance from main building, so its safety remains uncompromised. drawing on fig. 4 shows the simplified part of a building model designed by application of autocad. the forms presented in a given scale are perceived as smooth, although after proper magnification it becomes visible that all the mirrors (glass wall, or window) are absolutely flat, in fact. despite the choosing of ellipse shape for the base contour, the orientation of each window is specified with the “solar angle calculator” tool, integrated in autocad. solar panels’ holding tower built along journal of sustainable architecture and civil engineering 2020/1/26 50 one focal axis in given model, because it is enough for illustration of suggested principle. more effective focusing of solar energy will be possible by the mirrors arranged along cylindrical surface, but this would be justified in colder climatic conditions or in a case when the solar energy directly converted in a heat (or at a joint application of this technique). it means, that choosing of the building shape generally allows us to get the substantial improvement of energy efficiency. the full shape, shown on fig. 4, is conditional, because just part of south walls work as a reflector, the rest body of the building can be designed with any other 4 thus, the number of solar panels are optimized and mounted on separately arranged tower. accumulators and other accessories also placed in the same tower, at a distance from main building, so its safety remains uncompromised. drawing on fig. 4 shows the simplified part of a building model designed by application of autocad. the forms presented in a given scale are perceived as smooth, although after proper magnification it becomes visible that all the mirrors (glass wall, or window) are absolutely flat, in fact. despite the choosing of ellipse shape for the base contour, the orientation of each window is specified with the "solar angle calculator" tool, integrated in autocad. solar panels' holding tower built along one focal axis in given model, because it is enough for illustration of suggested principle. more effective focusing of solar energy will be possible by the mirrors arranged along cylindrical surface, but this would be justified in colder climatic conditions or in a case when the solar energy directly converted in a heat (or at a joint application of this technique). it means, that choosing of the building shape generally allows us to get the substantial improvement of energy efficiency. the full shape, shown on fig. 4, is conditional, because just part of south walls work as a reflector, the rest body of the building can be designed with any other architectural concept. there are the areas on the south face (especially on lower floors) contribution of which is minimal and accordingly, here it is possible to replace glass with other material. for illustration of benefits associated with the application of suggested principle, it can be compared with so-called passive water heaters (morsink-georgali et al. 2017). in multi-storey urban-type buildings, usually they are mounted on the roofs and mainly are available only for the residents of upper-floors. such an equipment needs the special thermally insulated case, glass roof and other components and only expensive models contain the reflectors of solar rays. as an alternative version, we can discuss the scheme, working for the whole building. the main component solar energy concentrator (reflector) emerged practically free-of-charge by initial positioning of windows and other glass surfaces. the solar radiation reflected from it falls on narrow glass tower, where the cheapest black plastic pipes used as water heater and conductor. overall coast of such integrated system is smaller than sum of separate standard solar energy water heaters. initial choosing of building shapes in such manner is reasonable even if not intended immediate full completion of architecture with autonomous energy system, because it is so flexible that enables late consummation and/or replacement of converters working in different modes and/or combinations. the intervention into city environment with any new building frequently can cause certain disturbance in adjoining spaces, but our innovation possess advantage even above usual rectangular buildings. the matter is that suggested shapes have especial property to collect the reflected daylight in a focal plane where receivers of energy are located. by this reason its undesirable influence on surrounding buildings is absolutely excluded. i.e. application of the suggested principle even theoretically cannot cause discomfort for people in neighboring location. 3. wind energy fig. 4. building model architectural concept. there are the areas on the south face (especially on lower floors) contribution of which is minimal and accordingly, here it is possible to replace glass with other material. for illustration of benefits associated with the application of suggested principle, it can be compared with so-called passive water heaters (morsink-georgali et al. 2017). in multi-storey urban-type buildings, usually they are mounted on the roofs and mainly are available only for the residents of upper-floors. such an equipment needs the special thermally insulated case, glass roof and other components and only expensive models contain the reflectors of solar rays. as an alternative version, we can discuss the scheme, working for the whole building. the main component solar energy concentrator (reflector) emerged practically free-of-charge by initial positioning of windows and other glass surfaces. the solar radiation reflected from it falls on narrow glass tower, where the cheapest black plastic pipes used as water heater and conductor. overall coast of such integrated system is smaller than sum of separate standard solar energy water heaters. initial choosing of building shapes in such manner is reasonable even if not intended immediate full completion of architecture with autonomous energy system, because it is so flexible that enables late consummation and/or replacement of converters working in different modes and/or combinations. the intervention into city environment with any new building frequently can cause certain disturbance in adjoining spaces, but our innovation possess advantage even above usual rectangular buildings. the matter is that suggested shapes have especial property to collect the reflected daylight in a focal plane where receivers of energy are located. by this reason its undesirable influence on surrounding buildings is absolutely excluded. i.e. application of the suggested principle even theoretically cannot cause discomfort for people in neighboring location. fig. 4 building model usage of wind as a renewable energy source obviously has longer history, than the solar panels. nowadays the total capacity of wind energy-aggregates amounts to half terawatt. the wind on the earth also related to the absorption of sun’s radiation and its application also complicated by variability of wind direction and speed. therefore, it is necessary to provide auto-correction wind energy 51 journal of sustainable architecture and civil engineering 2020/1/26 of generator’s wings’ orientation. theoretically it is also possible to regulate the wind flow (like solar energy concentration) and such schemes have already appeared in practice (allaei and andreopoulos 2014). in the proposed concept, where the external shape of a building has the leading importance, the compensation of obstructive variable parameters is realized by stationary constructions, not with special dynamic, so called, “tracking” systems. the optical properties of 3d construction shown on the drawing 4, provide such possibility of auto correction, moreover it turned out that such building, having claw-like section, possesses also the ability to regulate the wind flow. it can be said, symbolically, that the shape of a building can perform the function of a sail, but a building will not be moved, its shape just collect the wind flow, kinetic energy of which will be converted into electricity. drawing 4 shows cylinder-shaped sections, where the wind standard aggregates can be arranged, but significant increase of their efficiency (adjustment to the weak wind) is possible by the special constructions having vertical spin axis and semi-cylindrical wings. the profitable joint application of the solar and wind energies, under proposed scheme, is possible in such geographic locations (e.g. in ravines) where the wind annual dominant direction coincides with the scheme requirements. in any case, the buildings with similar external shape cause a local turbulence and suppress the power of wind in a city. interrelation between external shape of buildings with their energy saving characteristics became actual even without involving of power-producing modules (barea and gelard 2018, akadiri et al. 2012, raof 2017). the main component of suggested design, local system for solar energy conversion, equipped with the power accumulation module, destined for dc direct current. in due time, at the beginning of electrical grid establishment (interconnected network for delivering electricity from producers to consumers) priority was given to ac (alternating current), because it makes easier to regulate energy loses during transmission of power. however, dc is more profitable at a local generation of electricity, because direct current machines and generators are more compact, and have better coefficient of efficiency. thus, instead of ac generators currently used in so-called wind stations, local wind energy conversion systems must be based on dc generators. such a solution especially justified when the accumulators’ module already exists, e.g. at the joint application of wind and solar energy convertors. in this case, additional expenses limited just by the price of wind powered generators. the automatic operation of the whole system can be performed by quite simple controller. the power generated by such system used directly, without any losses. accumulators are supplied for charging only during excessive generation, what maximally increases coefficient of efficiency for the whole system. taking into account the general development of modern semi-conductor industry, it can be said that further application of 220 volt ac networks it is unreasonable. high voltage is hazardous not only as shocking factor, more often it causes conflagration (caused by e.g. electrical breakdown). it will be better to supply home devices by dc lover 50 volt. under such standard, the majority of modern household electric appliances disengage from disadvantageous “voltage lowering transformers” and “ rectifier” modules. such an alteration leads to decreasing of home appliances costs and advancement of their safety. in fact, such global technological tasks do not belong to the field of architecture, although if these issues will be ignored by architects, it will be impossible to achieve such a scale innovation. one of the main challenges of xxi century is the rehabilitation of environment and saving of natural resources. we think that advancement of renewable energy consumption by adaption of the buildings shapes encourage realization of its tasks and lead to second stage of sustainable development, which can be characterized as “active green architecture”. systemic characteristics and conclusions journal of sustainable architecture and civil engineering 2020/1/26 52 akadiri p.o., ezekiel a., olomolaiye ch., olomolaiye p.o. design of a sustainable building: a conceptual framework for implementing sustainability in the building sector. buildings. v.2, issue 2. 2012. h t t p s : / / w w w . m d p i . c o m / 2 0 7 5 5 3 0 9 / 2 / 2 / 1 2 6 . https://doi.org/10.3390/buildings2020126 allaei d., andreopoulos y. invelox. description of a new concept in wind power and its performance evaluation. energy 69. 2014. https://www.sciencedirect.com/science/article/pii/s0360544214002837. https://doi.org/10.1016/j.energy.2014.03.021 esteves a., esteves m.j., mercado m.v., barea g., gelard d. building shape that promotes sustainable architecture. evaluation of the indicative factors and its relation with the construction costs. architecture research. 8(4). 2018. http://article.sapub. org/10.5923.j.arch.20180804.01.html. http://article. sapub.org/10.5923.j.arch.20180804.01.html krauter s., ochs f. integrated solar home system. renewable energy 29 (2004) 153-164. https://www. researchgate.net/publication/4078571_integrated_solar_home_system. https://doi.org/10.1016/ s0960-1481(03)00190-3 morsink-georgali f.z., kylili a., fokaides p.a. life cycle assessment of flat plate solar thermal collectors. journal of sustainable architecture and civil engineering (jsace). v.21, no 4, 2017. http://sace. ktu.lt/index.php/das/article/view/18299. https:// doi.org/10.5755/j01.sace.21.4.18299 raof b. the correlation between building shape and building energy performance. int. j. of adv. res. 5 (5). 2017. http://www.journalijar.com/ article/17383/the-correlation-between-building-shape-and-building-energy-performance-. https://doi.org/10.21474/ijar01/4145 shigeru ban architects. la seine musicale. e_journal archdaily. 28 june, 2017. www.archdaily.com trombe f., le phat vinh a. thousand kw solar furnace, built by the national center of scientific research, in odeillo (france). solar energy. v.15, issue 1, 1973, p. 57-61. https://www.sciencedirect.com/ science/article/pii/0038092x73900066. https://doi. org/10.1016/0038-092x(73)90006-6 valancius r., singh a., mutiari a., alexander c., de la cruz d.a., del pozo f.e. jr. solar photovoltaic systems in the built environment: today trends and future challenges. journal of sustainable architecture and civil engineering (jsace). v. 23, no 2, 2018. http:// sace.ktu.lt/index.php/das/article/view/21268. https://doi.org/10.5755/j01.sace.23.2.21268 references badri gorgiladze head of laboratory architectural physics and multimedia design at faculty of architecture, urban planning and design of georgian technical university main research area architecture, physics, informatics, computer modeling. address 77 kostava str., 0160, tbilisi, georgia tel. (+99532) 2233293, mob. (+99555) 195793 e-mail: b.gorgiladze@gtu.ge gocha mikiashvili professor international design school of georgian technical university main research area architecture. address 77 kostava str., 0160, tbilisi, georgia tel. (+99532) 2233895, mob. (+99599) 503281 e-mail: gochamikia@yahoo.com nino imnadze professor dean of faculty of architecture urban planning and design of georgian technical university main research area architecture, urban planning. address 77 kostava str., 0160, tbilisi, georgia tel. (+99532) 2227777, mob. (+99599) 223747 e-mail: n.imnadze@gtu.ge about the authors https://doi.org/10.3390/buildings2020126 https://doi.org/10.1016/j.energy.2014.03.021 https://doi.org/10.1016/s0960-1481(03)00190-3 https://doi.org/10.1016/s0960-1481(03)00190-3 https://doi.org/10.5755/j01.sace.21.4.18299 https://doi.org/10.5755/j01.sace.21.4.18299 https://doi.org/10.21474/ijar01/4145 https://doi.org/10.1016/0038-092x(73)90006-6 https://doi.org/10.1016/0038-092x(73)90006-6 https://doi.org/10.5755/j01.sace.23.2.21268 mailto:b.gorgiladze@gtu.ge mailto:gochamikia@yahoo.com mailto:n.imnadze@gtu.ge 5 journal of sustainable architecture and civil engineering 2019/1/24 guest editor preface it is with a great pleasure that i preface this special issue of the journal of sustainable architecture and civil engineering, which comprises invited papers submitted to the 1st forum wood building baltic 2019, organized between 27 february – 1 march 2019 in tallinn, estonia. the forum wood building baltic 2019 conference was a fantastic opportunity for scientists and practitioners to meet and exchange experiences and to learn from the best within the field. the conference was organized by tallinn university of technology in collaboration with estonian association of civil engineers, estonian woodhouse association, estonian forest and wood industries association, and forum holzbau. forum wood building baltic is the main conference for technical topics of wooden buildings: building physics, fire safety, and wooden nearly zero energy buildings etc. in the countries around baltic sea. participants were from following countries: austria, canada, switzerland, germany, denmark, estonia, finland, greece, lithuania, latvia, norway, sweden, united kingdom. scope of the conference was _ building physics (heat, air and moisture; moisture safety) _ nearly zero energy buildings (real energy use, cost reduction) _ fire safety (separating and load-bearing functions, protection) _ cross laminated timber buildings (materials, structures) this special issue includes nine articles, which cover different aspects from energy performance to building physics. the european energy policy pushes the member states to transform building stock into nearly zero-energy buildings (nzeb). kuusk et al collected data collected from existing nzeb day-care centres to analyse possible differences between predicted and actual energy performance and indoor climate. a more accurate and robust commissioning, design and construction process is needed for future nzeb day-care centers. the overall indoor environment was very good as occupant satisfaction was 90% or more. in majority of day-care centers, measured energy consumption is higher or even significantly higher than designed values. dodoo studied the lifecycle primary energy and greenhouse gas implications of five multi-storey building versions with different construction systems, considering flows from the production, operation and end-of-life phases and the full natural resources chains. results showed that the operation phase dominates the lifecycle primary energy use of the building system versions. the primary energy for building production is 4–18% lower for the analysed timber-based building systems compared to the reinforced concrete building alternative. the massive timber building system gives the lowest lifecycle primary energy and greenhouse gas balances. due to the increased interest for wood buildings by the market, new technologies based on cross laminated timber (clt) have been developed, enabling an evolution of high-rise buildings. the main problem with wood and timber as a construction material is that it is sensitive to moisture and water causing mould and/or rot damages, as well as insect pests, which might cause indoor air problems but also structural failures shortening the life time of the building. mjörnell and olsson recommend that timber is not exposed to water or long periods of high relative humidity (weeks), which means that design of moisture safe, robust structures, weather protection and moisture safe handling of material at the building site and construction methods must be used. a well-insulated, airtight and thermal bridge free building envelope is a key factor for nzeb. hallik and kalamees give the overview about airtightness of estonian wooden buildings. the airtightjournal of sustainable architecture and civil engineering 2019/1/24 6 ness of estonian wooden buildings has improved by a factor of 10 since the minimum requirements for energy efficiency have taken effect. systematic measurement practice also contributed to significantly lower air leakages. geving et al. studied effect of repeated moisture cycles on the air tightness of traditional clamped vapour barrier joints. the results showed that the first drying cycle resulted in significant increase of air leakage for clamped joints in the windand vapour barrier layer. adhesive tape on the joints resulted in the greatest reduction in leakage numbers where the center distance between the nails was high. current method of façade retrofitting with additional heat insulation is time consuming and does not always prove the desired efficiency levels. the use of prefabricated timber-based panels provides more finishing options, thicker insulation layers, optimal window placement, and faster construction rate. bumanis and pugovics presented experience from low energy consumption façade pilot project. after three years of service it is visible, that conditions within the panel and between the panel and existing wall are optimal and no formation of dew point was observed. kalbe and kalamees studied the influence of window frame thermal transmittance, window frame height and window installation depth on the energy demand of an nzeb and showed that show that decreasing the thermal transmittance and height of the window frame have a significant effect on the energy demand of the nzeb, while the effect of optimising window installation depth is insignificant. the most commercial insulation products today are based on oil. switching to more environmentally friendly materials to insulate the dwelling’s shell has to be everybody’s primary target. ninikas et al. studied thermal properties of insulation boards made of tree bark and hemp residues. due to regulations for building acoustics and developments in the construction industry, there is a demand for higher standards to be met in dwellings, especially for residential timber multi story buildings. bard-hagberg and vardaxis evaluated acoustic comfort in typical residential family buildings in sweden. the results indicate that impact noise can be an issue in timber buildings. the most important noise types that generate annoyance are: machinery noise in the building, neighbor’s walking and activity from the floor above or below, low frequency noise from outside. slight annoyance was also reported due to transmission of neighbors’ low frequency music and conversations. prof. dr. targo kalamees guest editor tallinn university of technology journal of sustainable architecture and civil engineering 2016/3/16 32 *corresponding author: fgiama@auth.gr economic evaluation of financial incentive schemes for energy retrofit projects in residential buildings http://dx.doi.org/10.5755/j01.sace.16.3.16200 parthena exizidou, vassos vassiliou frederick research center, nicosia, cyprus michalis menicou frederick university/department of mechanical engineering, nicosia, cyprus mn assimakopoulou, evangelia tsairidi national and kapodistrian university of athens/physics department, athens, greece petros christou frederick university/department of civil engineering, nicosia, cyprus received 2016/09/23 accepted after revision 2016/11/07 journal of sustainable architecture and civil engineering vol. 3 / no. 16 / 2016 pp. 32-45 doi 10.5755/j01.sace.16.3.16200 © kaunas university of technology economic evaluation of financial incentive schemes for energy retrofit projects in residential buildings jsace 3/16 even if the eu has made important progress towards meeting its climate and energy targets for 2020, the effects of financial instability due to the economic crisis are still apparent, especially in the southern european countries, acting as a great obstacle for residents to invest in energy retrofit projects in order to improve their house energy performance. eu member states striving to limit the risks that such investments entail and to aid with high upfront costs are using financial incentives in the form of funding schemes, grants, tax exemptions/reductions etc. as a way of spurring investments in energy efficient services and technologies. within this framework, the current study deals with the financial attractiveness of investments in the presence and absence of incentive schemes for energy retrofitting of residential buildings in three european countries (cyprus, greece and uk). the methodology followed uses, as a first step, three case studies of typical residential buildings, one for each country, for the computation of pre-retrofitting and post-retrofitting energy demands. material and labor costs that apply in each country together with energy costs and economic parameters are taken into account in order to sum up the initial energy upgrade budget for each case. the second step regards the computation of investment criteria such as npv and irr and the analysis is performed for a 30year period to account for the life-cycle of a building using economic parameters such as discounting and inflation rates. then, the particulars of each country’s funding scheme are incorporated into the economic model to reveal their benefits and evaluate their attractiveness. the final output of the study comprises a comparative analysis of the current funding schemes using present worth as an indicator for the evaluation of their application in each country. followed the analysis conducted it is concluded that the cypriot and greek funding schemes have a strong effect when applied and evaluated in all three countries. on the contrary, the uk’s funding scheme is not applicable in terms of financial attractiveness in the case of greece and cyprus. keywords: energy retrofits, residential buildings, funding schemes, economic evaluation. 33 journal of sustainable architecture and civil engineering 2016/3/16 introduction according to the european commission, eu has made important progress towards meeting its climate and energy targets for 2020. regarding greenhouse gas emissions, there was a reduction of 18% in the eu between 1990 and 2012, and is well on track to meet the 2020 target. the share of renewables in the eu’s energy mix in 2012 reached 14.1%, comparing to 8.5% in 2005 and energy efficiency is predicted to improve by 18% to 19% by 2020 (eu, 2015). however, an integrated policy framework for the period up to 2030 is needed to ensure regulatory certainty for investors and a coordinated approach among member states. the new 2030 targets aim to help the eu achieve a more competitive, secure and sustainable energy system and to meet its long-term 2050 greenhouse gas reductions target. the 2030 targets can be summarized to the following (ec, 2014): _ a 40% cut in greenhouse gas emissions compared to 1990 levels _ at least a 27% share of renewable energy consumption _ a 30% improvement in energy efficiency (compared to projections of 2020) the european commission proposed a 30% energy savings target for 2030, following a review of the energy efficiency directive (directive 2012/27/eu, 2012). the proposed target builds on the achievements already reached: new buildings use half the energy they did in the 1980s and industry is about 19% less energy intensive than in 2001. the european council, however, endorsed an indicative target of 27% to be reviewed in 2020 having in mind a 30% target. in addition, it has been stated that the cost of meeting the targets does not substantially differ from the price need to be paid to replace ageing energy systems. the main financial effect of decarbonisation will be to alter our energy behavior and turn towards low-carbon technologies. however, maio et al (2012) and patlitzianas (2011) highlight that one of the main obstacles for achieving high energy efficiency standards, regards financing such projects when appropriate and competitive financial schemes are absent. problem definition the successful mobilization and scale up of investments in energy upgrade projects in the building sector has to overcome important obstacles nowadays due to the ongoing economic crisis that eu is facing. uncertainty and risk created by current economic state of various eu member states has caused according to bpie (2010) a freeze or deceleration on critical energy projects and a delay in energy technology development. in addition, as the unemployment rate is increasing, investing in energy efficiency measures in households is considered a “luxury”. as indicated by frederiks et al (2015), investment costs in energy efficiency measures are considerable and immediate, requiring liquidity, while benefits can be seen gradually over time. on the other hand, homeowners are more and more interested in such projects as it is the only way to reduce energy demands and thus energy consumption and annual utility expenses. to tackle this challenge there is a need of widespread adoption and implementation of effective policies and support programmes. according to global buildings performance network, effective policy packages for energy upgrade projects should include a collection of policy instruments that, combined, can upscale, finance, and promote deep renovations in member states. what is crucial indicated by shnapp (2015) is that respective policy packages of instruments should be formed according to the specific political, economic and social situation of the ms. last, according to menicou et al (2014) there is a need for an economic analysis to reveal the financial attractiveness for energy upgrades in the residential sector in the absence of government subsidies but also to evaluate current funding schemes in terms of effectiveness. this would facilitate local authorities and policy makers to develop such incentive schemes to constitute energy retrofits on residential buildings financially attractive to the general public and comply with european regulations. journal of sustainable architecture and civil engineering 2016/3/16 34 similarly, nikolaidis et al. (2009), applied several retrofit strategies in a typical greek building as a means to assess economic merits from alternative retrofit approaches. for the ranking of energy saving retrofit approaches, two evaluation criteria were used, namely, the internal rate of return (irr) criterion and the net present value (npv) criterion. asadi et al. (2012), and diakaki et al. (2008), used an alternative approach to this problem by applying multi-objective optimization techniques to a wide spectrum of alternative energy saving measures and to identify the most appropriate ones. however, many authors such as menassa (2011), gluch et al. 2004, gough et al. 1996, dowd 1998, ye et al. 2000, myers 1976, luehrman 1998, copland et al. 2004, and dell’isola 2003, state that the npv approach in assessing energy retrofit projects has several limitations. the main aim of the current study is to evaluate the attractiveness of current funding schemes for energy efficiency projects in the residential sector in cyprus, greece and uk. as a first step the methodology is assessing the energy requirements of typical residential buildings in cyprus, greece and uk and the energy savings resulting from the application of retrofit strategies. for this reason a research on characteristics of each country’s building stock that affect the energy performance of buildings has been conducted in order to identify a typical representative residential building to be used as a case study. thermal modelling of the representative building was used so as assess the energy savings potential and cost effectiveness of the application of retrofit strategies. in each case study the building can be described as typical in terms of age, location, construction characteristics and materials representing a considerable percentage of cyprus, greece and uk residential building stock, following evidence from various sources such as statistical services, scientific publications and outputs from research projects.trnsys v.17 was used to simulate heating and cooling energy consumption of the typical residential buildings over a 1 year period for several retrofit scenarios. in all three cases the same building was used in terms of type of construction (detached 2 story dwelling), size (205 m2), orientation (south – southwest), internal layout and number of occupants (family of 5) and differentiated in construction materials. five retrofit scenarios are considered based on the particulars of each funding scheme. the scenarios comprise improvements of the external walls’ u-value by adding insulation (scenario 1-s1), improvements of the roofs’ u-value by adding insulation (scenario 2-s2), improvements of the glazing by replacing old panes with energy efficient ones (scenario 3-s3), improvements on the envelope of the building regarding opaque components (scenario 4-combined s1+s2) and finally improvements on the envelope of the building regarding opaque and transparent components (scenario 5-combined s1+s2+s3). monetary cost estimation of each retrofit scenario considered, marks the initialisation of the economic analysis for the base case economic scenario. then, the percentage reduction in heating and cooling requirements to be brought about by each retrofit scenario is calculated. these percentages are utilised to estimate the annual expected monetary savings for each scenario considered. as soon as the annual expected savings are determined, a discounting factor is applied to calculate net present value (npv) of each retrofit scenario considered. current funding schemes with the respective terms and conditions are applied in order to form economic scenarios for each retrofitting scenario in each country. subsidies and remaining amounts based on the initial investment budget of each retrofit scenario are calculated. last but not least, present worth is then computed so as to evaluate the funding schemes and compare them for each retrofit scenario in each country. energy savings potential the assessment of the energy savings potential for the typical residential buildings in cyprus, greece and uk was performed through the modelling and simulation procedure. focus has been given to the heating and cooling loads of the pre-retrofitting and post-retrofitting simulations. as methodology 35 journal of sustainable architecture and civil engineering 2016/3/16 seen through fig. 1, fig. 2 and fig. 3, depicting the simulation results, the initial thermal loads are dependent on the initial construction characteristics revealing how energy intensive typical buildings are. the “trend” at the graphs depicts the change in post-retrofitting heating and cooling loads. fig. 1 heating and cooling loads for the residential building in cyprus and the respective energy demand change (trend) for each scenario fig. 2 heating and cooling loads for the residential building in greece and the respective energy demand change (trend) for each scenario fig. 3 heating and cooling loads for the residential building in uk and the respective energy demand change (trend) for each scenario economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. journal of sustainable architecture and civil engineering 2016/3/16 36 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. table 1 key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 fig. 4 internal rate of return and net present value results for the base-case economic scenario 2.2 economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. table 1. key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. fig. 4. internal rate of return and net present value results for the base-case economic scenario 2.2 economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. table 1. key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. fig. 4. internal rate of return and net present value results for the base-case economic scenario 2.2 economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. table 1. key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. fig. 4. internal rate of return and net present value results for the base-case economic scenario 2.2 economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. table 1. key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. fig. 4. internal rate of return and net present value results for the base-case economic scenario 2.2 economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. table 1. key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. fig. 4. internal rate of return and net present value results for the base-case economic scenario 2.2 economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. table 1. key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. fig. 4. internal rate of return and net present value results for the base-case economic scenario 2.2 economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. table 1. key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. fig. 4. internal rate of return and net present value results for the base-case economic scenario 2.2 economic analysis the aforementioned simulation results of the reference building and the respective scenarios are used as an input to the economic analysis. the investment budget (investment required) for each retrofit scenario was an outcome of the computation of the total cost of retrofitting measures (materials and labor) for each retrofit scenario depending on the market prices of each country (cyprus, greece, uk). common values that apply for each retrofitting activity can be seen in table 1. statistical data on current household energy needs in terms of grid-supplied electricity and heating oil/ natural gas are used so as to calculate the estimated energy consumption reduction followed be the application of the energy demands reduction percentage. table 1. key input data for cyprus, greece and uk energy & investment parameters cyprus greece uk investment horizon (yrs) 30 30 30 discounting rate 6.4% 6.4% 6.4% inflation rate of cost energy (electricity & heating oil) 2.5% 2.5% 2.5% external wall retrofitting cost /m2 € 45.0 € 50.0 €8.1 roof retrofitting cost /m2 € 35.5 € 40.0 €3.5 glazing dbl low-e cost /m2 € 234.0 € 280.0 €291.0 annual requirements in heating oil/ natural gas (kwh) 15271 21273 31019 price of heating oil/ ng per kwh (year zero) € 0.0971 € 0.1262 €0.09 annual cost of heating oil/ ng (year zero) € 1,482.62 € 2,684.94 €2,697 annual requirements in grid supplied electricity cooling (kwh) 1,351 444 0 cost per kwh € 0.27 € 0.15 €0.18 annual cost of grid supplied electricity € 364.72 € 66.65 € 0.00 as a following step, detailed economic calculations took place so as to estimate the net present value (npv) and internal rate of return (irr). the base-case economic scenario for the three countries refers to the energy upgrade project in the absence of funding schemes and the results of which can be seen in fig. 4. fig. 4. internal rate of return and net present value results for the base-case economic scenario funding schemes integration the cypriot funding scheme “eergy upgrade at households” the current scheme, which is the first integrated scheme for energy upgrades of residential buildings in cyprus, was published by the ministry of energy, commerce, industry and tourism during march 2015. the aim of the scheme is to promote energy efficiency through the implementation of large-scale energy upgrading interventions of the existing building stock in the country with a view to improving energy efficiency in households, including the use of renewable energy sources (res). the scheme is developed under the operational programme “competitiveness and sustainable development” 2014-2020 with public expenditure of €16.5μ for the respective programming period. it covers investments that concern the supply and installation of new equipment/ 37 journal of sustainable architecture and civil engineering 2016/3/16 material and are mature technologies and not in the stage of research and development. the funding programme refers to integrated energy upgrade of buildings or building units used as residences, to achieve energy efficiency class at least b in the energy performance certificate (epc) or to reduce energy consumption of at least 40% compared to the overall home energy consumption before the upgrade. the amount of public financing is 50% of the total approved budget. for cases of vulnerable consumers, the amount of public funding is increased to 75%. the grant amount for energy upgrade of each building can be up to € 15,000. the greek funding scheme “energy efficiency at household buildings” the program “energy efficiency at household buildings”, published during may 2011 by the ministry of environment, energy and climate change, was designed having as a goal the promotion of integrated energy-saving interventions in the residential building sector and with the main objective to reduce the energy requirements of buildings, the ghg emissions that contribute to the deterioration of global warming and to achieve a cleaner environment. it offered citizens incentives to carry out the most important interventions, aimed at improving their houses’ energy efficiency, while at the same time contributed to the achievement of greece’s energy and environmental targets. it is funded by the european union (european regional development fund) and national resources, through the regional operational programmes and the operational programmes “competitiveness and entrepreneurship”, “environment and sustainable development” nsrf 2007-2013. the total public expenditure of the program is €396μ. the eligibility of the program expenditure expired at the end of december 2015 and it will be completed no later than the end of 2017. the funding subsidized categories were based on annual incomes and can be summarized in table 2. table 2 categories of the greek funding scheme category a1 a2 b personal income ≤12.000€ 12.000€ < p.i. ≤ 40.000€ 40.000€ < p.i. ≤ 60.000€ family income f.i. ≤ 20.000€ 20.000€ < f.i. ≤ 60.000€ 60.000€ < f.i. ≤ 80.000€ subsidy 70% 30% interest-free loan (interest subsidy of 100% up to 31.12.2015) 35% 65% interest-free loan (interest subsidy of 100% up to 31.12.2015) 15% 85% interest-free loan (interest subsidy of 100% up to 31.12.2015) the uk funding scheme “green deal” the green deal is a uk government backed initiative, launched initially in october 2012 by the department of energy and climate change to permit loans for energy saving measures for properties in uk. through this scheme homeowners were able to understand the energy-saving improvements that can be applied to their homes and find companies to carry out the work, by giving access to a number of options for paying for the improvements, including green deal finance. the uniqueness of the green deal stands in the fact that green deal loans are repaid through the electricity bill of the tenant. another characteristic of the green deal contract is that it belongs to the property, meaning that the loan will be repaid by any tenant that resides in the property. a small amount is taken from the meter each day if there is a prepayment meter. if the occupant moves, he no longer benefits from the improvements and therefore stops paying for them. this system is known as the ‘golden rule’ the annual repayments on the loan shouldn’t be more than the savings made on the energy bills. regarding interest rates, they are fixed for the full term of the plan so the repayments are fixed but there’s no set rate. the interest rate will be determined by the amount of the finance plan and are dependent on the provider. journal of sustainable architecture and civil engineering 2016/3/16 38 funding schemes under the green deal comprised 3 offers: table 3 funding scheme offers under the green deal funding scheme-offer 1 funding scheme-offer 2 funding scheme-offer 3 up to €1,115 subsidy towards the cost of installing any 2 of the following: _ a condensing gas boiler on mains gas _ glazing replacement _ energy efficient replacement external doors _ cavity wall insulation _ floor insulation _ flat-roof insulation _ insulation for a room in the roof _ a replacement warm air unit _ fan-assisted storage heaters _ a waste water heat recovery system up to €557 more if the application is made within 12 months of buying a home possible to claim back up to €111 towards the cost of the green deal assessment if energysaving improvements are installed through the gdhif (green deal home improvement fund) it is worth noting that there was previously a 4th offer regarding solid wall insulation (internal or external) but currently the scheme is closed. around 6.6 million homes in the uk have solid walls. the respective scheme funded 67% of the budget, up to a maximum of €4,460. the new program is focusing on cavity wall insulation and other measures. despite the fact that the green deal once presented and launched seemed highly promising in regards to the effects that the scheme will have in energy renovation of residential buildings, there were quite a few voices of doubt. there has been a wide discussion regarding the benefits, restrictions and gaps of the scheme. common worries refer to the fact that the total cost of the parts, labor and finance should always be less than the total savings made. but the fact that interest is charged on the loan at about 7% suggests this is going to be hard to achieve. other uncertainties that arise, are based on the effect a green deal loan could have on a house sale. the loan is linked to the house, rather than to the individual, and as the scheme is still relatively new it is unclear whether this might make the property harder to sell. last but not least, since the energy savings are directly linked to the user in terms of different energy demands and thus different consumption, it can create a different outcome if another tenant occupies the house. the user’s type and behavior is affecting a great deal the successfulness of the green deal scheme applied in a house. however, after a series of amendments made in the basic core of the scheme, wide acceptance seemed to be gained by householders. summing up the three funding schemes that apply in cyprus, greece and uk used in the analysis, their particulars, encoded, can be seen in table 4. the schemes are categorized into 6 groups, two table 4 summary of funding schemes for each country (cyprus, greece, uk) abbreviation short description cyp 1 (cyprus 1) vulnerable people (75%) cyp 2 (cyprus 2) non-vulnerable people (50%) gr 1 (greece 1) f.i. ≤ 20.000€ or p.i.≤12.000€ (70% up to 10500€) gr 2 (greece 2) 20.000€ < f.i. ≤ 60.000€ or 12.000€ < p.i. ≤ 40.000€ (35% up to 5250€) gr 3 (greece 3) 60.000€ < f.i. ≤ 80.000€ or 40.000€ < p.i. ≤ 60.000€ (15% up to 2250€) uk 1 up to 1115€ for combination of at least two measures 39 journal of sustainable architecture and civil engineering 2016/3/16 for cyprus based on the type of applicant (vulnerable or non-vulnerable category), three for greece depending on annual income of the applicant and one for the uk. results and discussion each funding scheme was applied to all three countries in order to evaluate the applicability of them in each country and compare them in terms of financial attractiveness within the investment horizon. table 5, table 6 and table 7 present the particulars of each funding scheme when applied to each country. the investment required for each retrofit scenario varies depending on the country and thus the actual amount of grant is a different amount in each case. loans are considered only in the case of the greek funding scheme due to the fact that it is the only scheme that provides solid terms and reductions in interest rates in the case of loaning the remaining amount of the budget after the grant. regarding the remaining amount after the grant, for the cyprus and uk funding schemes; it is assumed that the applicant provides it. the same applies for the greek funding scheme in case the grant and loan are not sufficient for the investment required. values with red color signify that this is the maximum amount that can be subsidized for the specific scenario regardless of the percentage of the subsidy. these amounts in red can be seen in the case of the cypriot funding scheme in scenarios 1, 2 and 3 due to a limitation of the scheme in subsidies regarding single measures in retrofitting (eg. scenario 2: only roof insulation). in the case of the greece and uk funding schemes it signifies that the maximum limit is reached which is occurring in scenarios 4 (s1+s2) and 5 (s1+s2+s3) representing a combination of measures and not in single retrofitting measures. greece and uk funding schemes have the same general maximum limit for all categories (scenarios) of retrofitting in contrast with the cyprus funding scheme where scenarios 1, 2 and 3 have a different maximum limit from scenarios 4 (s1+s2) and 5. observing the tables it can be also noticed that the uk funding scheme is not applicable for scenarios 1, 2 and 3 and this is because the green deal can only be applied when the investment refers to a combination of retrofitting measures and not in single measures. according to table 5, if the greek funding scheme is applied to cyprus, for scenarios 1, 2 and 3 there is no remaining amount to be invested by the applicant. the interest rate is fully subsidized for a 6 year loan and thus it is the most attractive one in case the applicant is not capable in providing the remaining amount besides the grant. for the case of greece (table 6), the greek funding scheme (grant and loan) is proved sufficient for scenarios 1, 2, 3 and 4 and only scenario 5 has a remaining amount to be covered by the applicant. as observed in table 7, for the case of uk, the uk funding scheme is the less attractive one in terms of subsidization amount. on the other hand, the greek funding scheme covers all five scenarios (grant and loan) and the cypriot funding scheme even if it does not provide terms for a loan, the remaining amount is considerably less than the one based on the uk funding scheme. however, it is worth noting that the green deal subsidized other interventions with different amounts in previous versions in the past. following the quantification of the grant, loan and remaining amount that corresponds to each scenario for each country, the attractiveness of each funding scheme should be evaluated by an economic indicator taking into consideration the diminishing value of money over the predefined life-cycle of a building which corresponds to 30 years. time value of money is addressed by applying a discounting factor to anticipated cash flows over the project’s life considered (30 years). the present worth (pw) indicator is computed, which sums the anticipated cash flows over the project’s life after applying this discounting factor. the computation of the pw indicator and a comparison between the funding schemes for each retrofit scenario for the case of cyprus are depicted in fig. 5. journal of sustainable architecture and civil engineering 2016/3/16 40 table 5. application of funding schemes for the case of cyprus cyprus investment required scenario 1 (external walls) scenario 2 (roof) scenario 3 (windows) scenario 4 ( s1+s2) scenario 5 (s1+s2+s3) € 12,875 € 4,530 € 7,020 € 17,404 € 24,424 grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) c yp ru s in ce nt iv es cyp 1 2,500 0 10,375 2,500 0 2,030 2,500 0 4,520 13,053 0 4,351 15,000 0 9,424 cyp 2 2,500 0 10,375 2,500 0 2,030 2,500 0 4,520 8,702 0 8,702 12,212 0 12,212 g re ec e in ce nt iv es gr 1 9,013 3,863 0 3,171 1,359 0 4,914 2,106 0 10,500 4,500 2,404 10,500 4,500 9,424 gr 2 4,506 8,369 0 1,586 2,945 0 2,457 4,563 0 5,250 9,750 2,404 5,250 9,750 9,424 gr 3 1,931 10,944 0 680 3,851 0 1,053 5,967 0 2,250 12,750 2,404 2,250 12,750 9,424 u k in ce nt iv es uk 1 0 0 12,875 0 0 4,530 0 0 7,020 1,388 0 16,016 1,388 0 23,036 table 6. application of funding schemes for the case of greece greece investment required scenario 1 (external walls) scenario 2 (roof) scenario 3 (windows) scenario 4 (s1+s2) scenario 5 (s1+s2+s3) € 8,400 € 5,104 € 14,305 € 13,504 € 27,809 grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) c yp ru s in ce nt iv es cyp 1 2,500 0 5,900 2,500 0 2,604 2,500 0 11,805 10,128 0 3,376 15,000 0 12,809 cyp 2 2,500 0 5,900 2,500 0 2,604 2,500 0 11,805 6,752 0 6,752 13,905 0 13,905 g re ec e in ce nt iv es gr 1 5,880 2,520 0 3,573 1,531 0 10,014 4,292 0 9,453 4,051 0 10,500 4,500 12,809 gr 2 2,940 5,460 0 1,786 3,318 0 5,007 9,298 0 4,726 8,778 0 5,250 9,750 12,809 gr 3 1,260 7,140 0 766 4,338 0 2,146 12,159 0 2,026 11,478 0 2,250 12,750 12,809 u κ in ce nt iv es uk 1 0 0 8,400 0 0 5,104 0 0 14,305 1,388 0 12,116 1,388 0 26,421 table 6. application of funding schemes for the case of uk uk investment required scenario 1 (external walls) scenario 2 (roof) scenario 3 (windows) scenario 4 (s1+s2) scenario 5 (s1+s2+s3) € 2,089 € 396 € 7,830 € 2,484 € 10,314 grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) grant (€) loan (€) remain (€) c yp ru s in ce nt iv es cyp 1 1,567 0 522 297 0 99 2,500 0 5,330 1,863 0 621 7,736 0 2,579 cyp 2 1,045 0 1,045 198 0 198 2,500 0 5,330 1,242 0 1,242 5,157 0 5,157 g re ec e in ce nt iv es gr 1 1,462 627 0 277 119 0 5,481 2,349 0 1,739 745 0 7,220 3,094 0 gr 2 731 1,358 0 139 257 0 2,741 5,090 0 869 1,615 0 3,610 6,704 0 gr 3 313 1,776 0 59 337 0 1,175 6,656 0 373 2,111 0 1,547 8,767 0 u κ in ce nt iv es uk 1 0 0 2,089 0 0 396 0 0 7,830 1,388 0 1,096 1,388 0 8,926 41 journal of sustainable architecture and civil engineering 2016/3/16 for scenario 1 which refers to external wall retrofitting, the greek funding schemes stand out having the highest value of pw and followed by the cyprus funding schemes. gr 1 seems to be the most profitable scheme of all and refers to applicants of lower annual income, up to 20000€ for family income and up to 12000€ for personal income. in these terms it can be compared with the cyp 1 standing for vulnerable people, although this category involves various types including disabled or families with many members besides annual income. regarding scenario 2, again gr 1 has the highest pw value. however in this case the 2nd and 3rd place occupy the cyp 1 and cyp 2 respectively and followed by gr 2 and gr 3. scenario 3 has the lowest pw values of all scenarios due to the high initial investment required. in this case the greek funding schemes have higher values and are followed by the cyprus funding schemes. for scenarios 1, 2 and 3, the uk funding scheme is not applicable for single measures and thus has the same pw value with the “no incentives” value. scenarios 4 and 5 are the most profitable of all. for both scenario 4 (s1+s2) and 5 (s1+s2+s3) the most attractive scheme is the cyp 1 followed, in scenario 4 (s1+s2), by gr 1 and in scenario 5 (s1+s2+s3) by cyp 2. in total, it can be concluded that for the cyprus case of retrofitting residential buildings, the cypriot funding schemes outbalance the rest in integrated energy upgrades with a combination of measures applied in the building envelope and openings. however, for single measures’ application, the greece funding schemes are more attractive. for the case of retrofitting residential buildings in greece, fig. 6 depicts the computation of pw values for each retrofitting scenario. as in the cyprus case, gr 1 has the highest value for scenarios 1 and 2 but the difference with the rest of the funding schemes has decreased here. scenario 3 is the less profitable scenario as the cost of retrofitting is even bigger than in the case of cyprus. regarding scenario 4 (s1+s2), gr 1 funding scheme is almost at the same level with cyp 1. the same outcomes can be observed in pw in scenario 5 (s1+s2+s3) where cyp 1 and cyp 2 are slightly better than gr 1. in general for the case of greece the greek funding scheme gr1 for low income applicants is as attractive as the cyp 1 with slight differences comparing to the cyprus case where the differences were more noticeable. concerning energy retrofitting of residential buildings in uk, there is a countable difference in the initial investment required for each retrofit scenario. this lies in the fact that residential buildings fig. 5 incentives comparison for the cyprus case of retrofitting based on pw indicator after applying this discounting factor. the computation of the pw indicator and a comparison between the funding schemes for each retrofit scenario for the case of cyprus are depicted in fig. 5. journal of sustainable architecture and civil engineering 2016/3/16 42 have different characteristics than the typical residential buildings that can be found in cyprus and greece and thus the procedures for retrofitting differ significantly. for example, cavity wall insulation is much cheaper than external wall insulation in cyprus and greece and much cheaper than solid wall insulation that a previous version of the green deal used to subsidize in the past. regarding the attractiveness of funding schemes applied in energy upgrade projects in uk, fig. 7 present the pw values computed for each retrofit scenario. pw values of funding schemes under scenarios 1, 2 and 4 (s1+s2) have slight differences between them. under scenario 3 and scenario 5 (s1+s2+s3), the funding scheme gr 1 is more attractive than the rest having however a slight difference with cyp 1 in the case of scenario 5 (s1+s2+s3). fig. 6 incentives comparison for the greece case of retrofitting based on pw indicator fig. 7 incentives comparison for the uk case of retrofitting based on pw indicator fig. 6. incentives comparison for the greece case of retrofitting based on pw indicator concerning energy retrofitting of residential buildings in uk, there is a countable difference in the initial investment required for each retrofit scenario. this lies in the fact that residential buildings have different characteristics than the typical residential buildings that can be found in cyprus and greece and thus the procedures for retrofitting differ significantly. for example, cavity wall insulation is much cheaper than external wall insulation in cyprus and greece and much cheaper than solid wall insulation that a previous version of the green deal used to subsidize in the past. regarding the attractiveness of funding schemes applied in energy upgrade projects in uk, fig. 7 present the pw values computed for each retrofit scenario. pw values of funding schemes under scenarios 1, 2 and 4 (s1+s2) have slight differences between them. under scenario 3 and scenario 5 (s1+s2+s3), the funding scheme gr 1 is more attractive than the rest having however a slight difference with cyp 1 in the case of scenario 5 (s1+s2+s3). fig. 7. incentives comparison for the uk case of retrofitting based on pw indicator fig. 6. incentives comparison for the greece case of retrofitting based on pw indicator concerning energy retrofitting of residential buildings in uk, there is a countable difference in the initial investment required for each retrofit scenario. this lies in the fact that residential buildings have different characteristics than the typical residential buildings that can be found in cyprus and greece and thus the procedures for retrofitting differ significantly. for example, cavity wall insulation is much cheaper than external wall insulation in cyprus and greece and much cheaper than solid wall insulation that a previous version of the green deal used to subsidize in the past. regarding the attractiveness of funding schemes applied in energy upgrade projects in uk, fig. 7 present the pw values computed for each retrofit scenario. pw values of funding schemes under scenarios 1, 2 and 4 (s1+s2) have slight differences between them. under scenario 3 and scenario 5 (s1+s2+s3), the funding scheme gr 1 is more attractive than the rest having however a slight difference with cyp 1 in the case of scenario 5 (s1+s2+s3). fig. 7. incentives comparison for the uk case of retrofitting based on pw indicator 43 journal of sustainable architecture and civil engineering 2016/3/16 it must be noted here that for the case of the uk funding scheme, the green deal presented in the current report is a follow up of a series of funding schemes unlike the greek funding scheme running for the past 4 years in greece and the cypriot funding scheme which is the first integrated funding scheme for energy upgrade projects in residential buildings in cyprus. this means that past version of uk funding schemes offered great assistance to home owners subsidizing such projects. conclusions the current work dealt with the applicability and attractiveness of funding mechanisms used by cyprus, greece and uk to not only improve the renovation rate in the residential building sector of their country but also to comply with the respective european directives as member states and contribute to eu efforts for achieving the energy efficiency targets. even though each policy package is different it seems that the cypriot and greek funding schemes have a strong effect when applied and evaluated in all three countries. both cyprus and greece have a subcategory that involves low income householders that can benefit in different terms by the funding schemes. on the contrary, the uk’s funding scheme, designed to serve uk’s building stock, is not applicable in terms of profitability in the case of greece and cyprus due to the distinct method of retrofitting according to different building characteristics leading to high costs of initial investment capital. an important conclusion drawn from this analysis is that even though each member state can benefit from successful policy measures adopted by other member states, the actual design of a funding scheme should be unique for each country taking into account political, economic and social aspects as well as the special features of its building stock. however, successful funding schemes can provide crucial insights for policy makers for the proper design of innovative financial instruments. it is also worth mentioning that almost all retrofit scenarios considered they do have positive financial merits in the absence of financial incentives. this is a critical conclusion that justifies investment in energy retrofit projects. however, a major drawback is the considerable investment in the front and the extensive payback period. the authors gratefully acknowledge the cyprus research promotion foundation (rpf) for funding the research project entitled “square mile retrofit project” (contract number: κοινα/eracobuild-vdp/0609) results of which are presented in this paper. acknowledgment asadi e., gameiro da silva m., henggeler antunes c., dias l. multi-objective optimization for building retrofit strategies: a model and an application. energy and buildings, 2012; 44: 81-87. https:/doi. org/10.1016/j.enbuild.2011.10.016 building performance institute europe (bpie), financing energy efficiency (ee) in buildings, brussels; 16 nov., 2010. copland t., tufano p. a real world way to manage real options. harvard business review, 2004; 82(3): 1–12. dell’lsola a. j., kirk kingston s. life cycle 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exizidou p., vassiliou v., christou p. an economic analysis of cyprus’ residential buildings’ energy retrofits, international journal of sustainable energy, 2015; 31: 3-4. https:/doi.org/10.1080/ 14786451.2013.873800 myers s.c. modern developments in financial management, new york: praeger/business & economics; 1976. nikolaidis y., pilavachi p., chletsis a. economic evaluation of energy saving measures in a common type of greek building. applied energy, 2009; 86: 2550-2559. applied energy, 2009; 86: 2550-2559. https:/doi.org/10.1016/j.apenergy.2009.04.029 patlitzianas k.d. an analysis of energy efficiency investments’ environment in greece – the potential role of jessica instrument, j. energy conversion and management, 2011; 52: 1. https:/doi. org/10.1016/j.enconman.2010.07.011 shnapp s. deep building renovation international policy guidelines, global buildings performance network (gbpn); jun., 2015. ye s., tiong r.l.k. npv at risk method in infrastructure project investment evaluation. journal of construction engineering and management, 2000; asce 126(3): 227–233. parthena (nopi) exizidou research associate frederick research center and frederick university, cyprus, school of engineering main research area energy efficiency of buildings, thermal modelling of buildings address 7, frederickou str., 1036, nicosia, cyprus tel.: +35722394394 e-mail: eng.ep@frederick.ac.cy michalis menicou assistant professor department of mechanical engineering, frederick university, cyprus main research area energy economics, industrial management address 7, frederickou str., 1036, nicosia, cyprus tel.: +35722394394 e-mail: eng.mm@frederick.ac.cy mn assimakopoulos assistant professor faculty of physics, division of environmental physics and meteorology, national and kapodistrian university of athens/, athens, greece main research area energy simulation, numerical methods, indoor environmental quality, energy conservation address national and kapodistrian university of athens, faculty of physics, division of environmental physics and meteorology, zografou campus, building phys-v, gr 15784, athens, greece tel.: +30 210 7276922 e-mail: masim@phys.uoa.gr about the authors 45 journal of sustainable architecture and civil engineering 2016/3/16 vassos vassiliou research associate frederick research center, cyprus main research area risk analysis, engineering economics, industrial management address 7, frederickou str., 1036, nicosia, cyprus tel.: +35722394394 e-mail: eng.vv@frederick.ac.cy evangelia tsairidi research associate faculty of physics, division of environmental physics and meteorology, national and kapodistrian university of athens/, athens, greece main research area energy simulation, numerical methods address national and kapodistrian university of athens, faculty of physics, division of environmental physics and meteorology, zografou campus, building phys-v, gr 15784, athens, greece tel.: +30 210-727 6830 e-mail: etsairidi@phys.uoa.gr petros christou associate professor department of civil engineering, frederick university, cyprus main research area structural analysis, historical buildings, numerical methods, sustainable construction address 7, frederickou str., 1036, nicosia, cyprus tel.: +35722394394 e-mail: eng.cp@frederick.ac.cy 53 journal of sustainable architecture and civil engineering 2019/2/25 *corresponding author: eneli.liisma@merko.ee a case study on the construction of a clt building without a preliminary roof received 2018/12/20 accepted after revision 2019/06/01 journal of sustainable architecture and civil engineering vol. 2 / no. 25 / 2019 pp. 53-62 doi 10.5755/j01.sace.25.2.22263 a case study on the construction of a clt building without a preliminary roof jsace 2/25 http://dx.doi.org/10.5755/j01.sace.25.2.22263 eneli liisma* as merko ehitus. järvevana tee 9g, tallinn 11314, estonia tallinn university of technology, department of civil engineering and architecture. ehitajate tee 5, tallinn 19086, estonia babette liseth kuus as merko ehitus. järvevana tee 9g, tallinn 11314, estonia villu kukk, targo kalamees tallinn university of technology, department of civil engineering and architecture. ehitajate tee 5, tallinn 19086, estonia introduction this paper focuses on cross-laminated timber (clt) and how it is affected by the dynamic properties of moisture during installation in the cold and humid climate of estonia. the moisture safety principles are designed using a case study of comparable activities with 4-d principles and on-site water content monitoring. on-site water content monitoring was done on the clt elements that were installed and a parallel polygon specimen. polygon testing was arranged with reduced size clt elements subject to different conditions, with some exposed to the climate, some protected from precipitation, and some covered with film. the moisture content (mc) of the uncovered horizontal clt element that was exposed to the climate reached over 25% after higher precipitation and the mc after prolonged direct exposure can reach up to 40% in a week, giving a clear signal of high risk areas for moisture safety. installing a partly weather protected clt element without a preliminary roof is a high-risk arrangement, but is essentially possible in a cold and humid climate. moisture safety planning and a lean strategy must be applied with timber construction. keywords: clt; moisture safety; construction quality; building technology; moisture content. the building and construction industry is facing a significant challenge in reducing its carbon emissions (lai et al., 2017). greater use of wood-based materials helps to reduce the use of fossil-fuel energy and to mitigate climate change. dodoo et al., (2010) show that the low-energy version of the cross laminated timber (clt) building gives the lowest lifecycle carbon emissions while the conventional version of the beam-and-column building gives the highest lifecycle emissions. clt-element design has been growing noticeably for the past decade in all leading european countries and in central europe in particular (brandner et al., 2016; hurmekoski et al., 2015; schickhofer et al., 2017). journal of sustainable architecture and civil engineering 2019/2/25 54 although the mechanical properties of clt are equivalent in scale to those of several other main construction materials, using timber poses the severe issue of moisture safety (öberg and wiege, 2018) as moisture is the most important factor affecting the durability of wood and damage to it. optimum moisture conditions for most decay fungi mean moisture content (mc) above fibre saturation, which is usually around 25-30% (carll and highley, 1999), and the upper safe limit for mc for clt structures is considered to be 15-17% by mass depending on the vapour permeability of the covering material (kukk et al., 2019; lepage et al., 2017). if the moisture that is built in from exposure to weather conditions cannot be dried out from timber construction during the installation process, moisture safety can be considered to be compromised. excess moisture means there is a critical issue in achieving moisture safety of wooden construction and shortens the service life of the building (brischke et al., 2006; kalamees, 2002). the construction industry by its nature has many particular problems and requirements (ofori, 2000). new technologies are resisted because they require changes to be made to processes that can entail risks and unforeseen costs (häkkinen and belloni, 2011). testing and evaluating new structures, technologies and construction processes in pilot projects helps to minimise risks before market launch. moisture management has been cited as a difficult and expensive process that arises when building with wood frame structures (globe advisors, 2016). as fully moisture safe clt construction technology is still relatively new in many countries, it also demands further research and development. three main options have been developed for weather protection during building, and these are scaffolding cover, stationary or movable roof cover, and climbable cover. temporary tents have been used in europe to protect entire project sites and provide good protection from rain, snow or wind (constance thivierge, 2011). in practice the temporary tents that can prevent rainwater damage or other weather protection solutions are not always used. this may be because the builder has inadequate experience of the moisture-safe construction principles, lacks knowledge of mould problems, or has previous experience with concrete structures that tolerate moisture a little better. if the temporary tent is omitted during the bidding stage, it is difficult to find the finances and time to add it to the construction budget and calendar later on. this study analyses the options and risks for constructing a clt-building without temporary movable tents covering the project site. the viimsi state gymnasium school building in estonia was selected as a pilot project. fig. 1 overall view of the installation process for the clt element (left). external and vertical clt elements getting additional protective canvas (right) methods the case study building the case study building, viimsi state gymnasium school in estonia, is one of the first public multi-storey buildings to be built mainly of clt (cross laminated timber). the design was produced by novarc group as and kamp arhitektid oü in 2017, and the building was constructed by merko ehitus eesti as in 2018. the floor area was 4300 m² and construction cost was 6.1 million euros. clt elements were used for the vertical and horizontal structure, fig. 1. 55 journal of sustainable architecture and civil engineering 2019/2/25 in this case study no temporary tent or preliminary roof for weather protection was set up during the installation process and so considerably greater risk was taken because there was no proper moisture safety plan in the bidding stage of the project. the clt elements were protected only by packaging pe foil and were sealed during the production process to ensure the mc of 13%±2% declared by the factory, peetri puit oü. moisture safety management principles the set up for this case study was to predict and map out the most critical positions of the clt elements that were exposed to weather conditions during the installation process with minimal precautionary measurements for moisture safety. preliminary on-site activities followed the “4d principles” of fpinnovations (wang, 2016) – deflection, drainage, drying, and durable material, see fig. 2. all the vertical elements were sealed and moisture safe, but all the horizontal elements were unsealed before installation and subsequently covered. accordingly the most critical positions are all the horizontal elements and the horizontal-vertical unit perimeter elements. on-site moisture safety was divided into full-scale monitoring of clt elements for their actual moisture status and monitoring of reduced size clt element polygons, which were compared with the building construction. additionally, laboratory measurements for capillary absorption were taken to understand the effect of water migration. fig. 2 4-d principles of moisture safety integrated into onsite activities and moisture content (mc) monitoring fig. 3 clt elements covered by pe foil before, during and after installation deflection drainage durability avoid standing water manage free water factory production control activities moisture safety ensured direct water contact mc monitoring mc < 16% mc > 16% drying local protection (film, canvas, inclined surface, wax) on-site moisture safety activities declared mc onsite and factory packaging wall elements were transported in packaging pe-foil and were kept in it during storage on site and after installation. the covering film for the floor element was removed before installation because it was joint specific, fig. 3. journal of sustainable architecture and civil engineering 2019/2/25 56 moisture measurement after installation of the clt-elements, the water content was monitored using a pin electrode moisture meter (extech mo290) with short pins of 10 mm for external layers and long pins of 80 mm to get internal results. the measuring was done during installation and the measuring points selected were the most critical positions for moisture, as discussed previously, fig. 4. fig. 4 sample of the high moisture risk position fig. 5 sample of the high moisture risk position clt wall element concrete floor electrode pin dots the joint between the clt wall element and the concrete floor with moisture meter electrode dots (left). a very extreme situation with heavy snowfall on the floor elements and near the clt wall element, however snow was instantly removed after precipitation (right) monitoring of moisture safety with a reduced size clt element parallel polygon testing with reduced size vertical and horizontal clt elements (300×1000×60mm) was done near to the building site to compare the mc of unsealed and covered clt elements with the unsealed and uncovered elements in the real life building, fig. 5. three constant situations were set up to provide different moisture conditions, with elements unsealed and exposed to all weather conditions, elements unsealed but under protective cover, and elements sealed in the factory and kept unopened. capillary water absorption was measured in laboratory conditions (20 ± 2oc and rh 50 ±5%). both vertical and horizontal element water exposure was imitated as seen in fig. 6. 57 journal of sustainable architecture and civil engineering 2019/2/25 fig. 6 capillary absorption imitation of vertical clt element (left). capillary absorption of the horizontal clt element (right) fig. 7 installed clt elements: after one week (top left), after five weeks (top right), and after eight weeks (bottom left). precipitation during the installation period (bottom right) construction process the clt installation period was eight weeks (20.02.2018 – 13.04.2018) and the installation of the clt elements was done during a period of relatively high precipitation. the total rain load was over 90 mm, with individual higher results in one week above 30 mm. fig. 7 shows the progress of the installation of the clt elements and the rain intensity during this period. the horizontal elements were moderately exposed to standing water and infrequent snowfalls, both removed within a maximum of 15 hours as one of the principles of 4-d. it must be stated that snowfall precipitation wasn’t measured separately during the construction process due to deflection and drainage activities. otherwise every 1 m3 of snowfall would add approximately 250 kg extra water risk for timber elements. the pre-planned 4-d moisture safety principles (fig. 2) were an innovation for construction company and were mostly followed. results 0 10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 8 pr ec ip it at io n , m m installation week (february-april, 2018) weekly precipitation total precipitation journal of sustainable architecture and civil engineering 2019/2/25 58 site visits indicated that even when the horizontal surfaces were covered with preliminary foil, microbial growth was not prevented and in extreme cases the growth could be seen with the naked eye. fig. 8 water (left) and microbial growth (right) on the clt fig. 9 the moisture content dynamics of the clt elements after precipitation in the final phase of installation moisture content in clt elements exposed to precipitation the manufacturer declared the mc of the clt was 13% ± 2%. in this case the study elements transported to the site had an initial water content of up to 13%, and mostly around 10% by mass. the mc of the clt elements reached up to 15% by mass at the end of the installation process. nevertheless a decreasing dynamic was apparent in time due to the sorption process, fig. 9. it was noted that the short pin electrodes (10 mm) clearly found higher moisture content in the horizontal elements than in the horizontal-vertical joints. however, the long pin electrodes (80 mm) indicated irregular moisture content results. if extremums are excluded, the average results are equivalent whatever the direction of the clt element. this points to internal moisture safety for the clt elements. however, precipitation type (rain/snow) wasn’t measured separately, it can be stated that rain has higher effect on mc compared to snow that was constantly removed from horizontal surfaces. but without deflection and drainage activities, snowfall would have considerable risk on the mc increase in clt elements when melted as described above. 0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 10 12 14 16 18 4/ 2/ 20 18 4/ 4/ 20 18 4/ 6/ 20 18 4/ 8/ 20 18 4/ 10 /2 01 8 4/ 12 /2 01 8 4/ 14 /2 01 8 4/ 16 /2 01 8 4/ 18 /2 01 8 4/ 20 /2 01 8 4/ 22 /2 01 8 4/ 24 /2 01 8 4/ 26 /2 01 8 4/ 28 /2 01 8 4/ 30 /2 01 8 5/ 2/ 20 18 5/ 4/ 20 18 5/ 6/ 20 18 5/ 8/ 20 18 5/ 10 /2 01 8 5/ 12 /2 01 8 5/ 14 /2 01 8 5/ 16 /2 01 8 p re ci pi ta ti on , m m m oi st ur e co nt en t, % time precipitation horizontal element horizontal-vertical joint horizontal-vertical joint unit measures with long pins horizontal element measures with long pins 59 journal of sustainable architecture and civil engineering 2019/2/25 polygon testing moisture content in the clt elements fig. 10 shows that after higher precipitation the uncovered and exposed horizontal clt elements reached a moisture content of over 25% that lasted several weeks before falling below the 17% limit with the short pins that measure the external layer. the longer pins measuring internal moisture showed water content was below 25% after the precipitation but it took a month to dry out to 17%. for the clt elements that were covered with no direct water contact, the mc remained under the upper safe limit of 17% both internally and externally. 0 5 10 15 20 25 30 0 5 10 15 20 25 30 pr ec ip ita tio n, m m m oi st ur e co nt en t, % precipitation, mm uncovered specimen covered specimen (average) uncovered specimen (average) mc upper safe limit covered specimen 0 5 10 15 20 25 30 0 5 10 15 20 25 30 pr ec ip ita tio n, m m m oi st ur e co nt en t, % fig. 10 mc monitoring of the horizontal clt elements in polygon testing: external mc with short pins (left); internal mc with long pins (right) fig. 11 mc monitoring of the vertical clt elements in polygon testing: external mc with short pins (left); internal mc with long pins (right) fig. 11 shows that the behaviour of the wall elements was similar but the mc was approximately 10 percentage points lower. the mc of the wall elements exceeded the upper safe limit and did not dry out during the final month of installation. the difference in the internal and surface moisture levels shows the importance of the measurement depth for the water content of the clt elements. the key factor that must be pointed out for the horizontal-vertical joint performance is that the bottom end of the vertical element must be sealed with rubber or another waterproof layer to block capillary water migration, as seen previously in fig. 6. 0 20 40 -10 10 30 pr ec ip ita tio n, m m m oi st ur e co nt en t, % precipitation covered specimen sademete eest kaitsud katsekeha mõõtmistulemused 0 5 10 15 20 25 30 0 5 10 15 20 25 30 pr ec ip ita tio n, m m m oi st ur e co nt en t, % the capillary absorption results from the laboratory tests of the clt elements show that prolonged direct water contact can lead to mc of up to 40% by mass in a week, which is a clear indicator of journal of sustainable architecture and civil engineering 2019/2/25 60 discussion conclusions high risk areas in the context of moisture safety. for future work, it would be relevant to examine water migration and its behaviour in the clt structure subject to the orientation of the timber fibre. the current study showed that installing partly weather protected clt elements without a preliminary roof is a high-risk arrangement in a cold-humid climate. the shortcomings in the construction technology, such as the lack of rain protection for the clt and the absence of any moisture safety protocol during the construction period may lead to high humidity conditions for long periods in the externally insulated clt panels, raising concern about condensation and the risk of mould developing (kalamees et al., 2014). therefore, moisture safety should be included as part of the design and manufacturing process and also the construction process. the byggaf method is a good example of this (mjörnell et al., 2011). öberg and wiege, (2018) showed that a roof cover is required if the expected rain load is above 40 mm or the building time is over two weeks. in this case study the horizontal elements were moderately exposed to standing water but it was removed within a maximum of 15 hours as one of the principles of 4-d. although the current study showed that a preliminary tent should be required for construction with clt when the aim is to construct a moisture safe building, clt buildings have been successfully put up in norway and sweden without weather protection. however, it must be noted, that standing water was strictly prevented. in contrast, a serious moisture failure was reported from the jätkäsaari district in finland, where a new rental housing block district has fallen prey to water damage just one month after the occupants moved in (bäckgren, 2017; yle, 2017). polygon testing showed that uncovered and exposed horizontal clt elements reached a moisture content of over 25% after higher precipitation. after exposure to prolonged direct water contact, the mc can reach up to 40% in a week. these results clearly support the use of temporary rain protection during the construction of wooden buildings. when the clt was protected during construction with preliminary pe-foils and 4-d moisture safety principles were implemented, the mc of the clt was lower. if direct water contact was immediately eliminated from the clt elements, the regions with the highest moisture risk are horizontal floor elements and floor-wall joints. critical on-site positions did not exceed the upper safe limit of mc of 17% in the clt elements with vapour permeable insulation, nor did the moisture migrate to the internal timber structure. this case study showed that without protection from a preliminary roof or temporary tent, installing clt elements without persistent moisture damage appearing is very risky, but still essentially possible. a factor that makes a considerable difference is the critical uncovered area limit. this case study finds that a locally protected area of up to 1350 m2 and approximately 90 mm of precipitation within the installation period are manageable parameters. however, it must be strictly understood that moisture safety pre-planning and a lean strategy must be applied with timber construction. acknowledgement we thank the merko ehitus eesti as site team for their cooperation and for helping with on-site activities and peetri puit oü for organising the clt polygon specimen. this research was supported by the estonian research council with personal research funding prg483 “moisture safety of 61 journal of sustainable architecture and civil engineering 2019/2/25 bäckgren, n., 2017. jätkäsaaren homehtuneet wood city puukerrostalot ovat stora enson osin rahoittama tutkimuskohde työmaalla testattiin, miten puurakentaminen onnistuu ilman sääsuojaa. rakennuslehti. brandner, r., flatscher, g., ringhofer, a., schickhofer, g., thiel, a., 2016. cross laminated timber (clt): overview and development. european journal of wood and wood products 74, 331-351. https:// doi.org/10.1007/s00107-015-0999-5 brischke, c., bayerbach, r., otto rapp, a., 2006. decay-influencing factors: a basis for service life prediction of wood and wood-based products. wood material science and engineering 1, 91-107. https:// doi.org/10.1080/17480270601019658 carll, c.g., highley, t.l., 1999. decay of wood and wood-based products above ground in buildings. journal of testing and evaluation. vol. 27, no. 2 (mar. 1999).:p. 150-158. 27, 150-158. https://doi. org/10.1520/jte12054j constance thivierge, 2011. building with clt panels durability considerations. wood design & building 38-41. dodoo, a., gustavsson, l., sathre, r., 2010. life cycle primary energy implication of retrofitting a wood-framed apartment building to passive house standard. resources, conservation and recycling 54, 1152-1160. https://doi.org/10.1016/j.resconrec.2010.03.010 globe advisors, 2016. study of insurance costs for mid-rise wood frame and concrete residential buildings. häkkinen, t., belloni, k., 2011. barriers and drivers for sustainable building. building research & information 39, 239-255. https://doi.org/10.1080/09613 218.2011.561948 hurmekoski, e., jonsson, r., nord, t., 2015. context, drivers, and future potential for wood-frame multi-story construction in europe. technological forecasting and social change 99, 181-196. https:// doi.org/10.1016/j.techfore.2015.07.002 kalamees, t., 2002. failure analysis of 10 year used wooden building. engineering failure analreferencesysis 9, 635-643. https://doi.org/10.1016/s13506307(02)00025-0 kalamees, t., paap, l., kuusk, k., mauring, t., hallik, j., valge, m., kalbe, k., tkaczyk, a.h., 2014. the first year’s results from the first passive house in estonia, in: arfvidsson, j., harderup, l.-e., kumlin, a., rosencrantz, b. (eds.), proceedings of 10th nordic symposium on building physics. 15-19 june 2014 lund, sweden, pp. 758-765. kukk, v., külaots, a., kers, j., kalamees, t., 2019. influence of interior layer properties to moisture dry-out of clt walls. canadian journal of civil engineering cjce-2018-0591. https://doi.org/10.1139/ cjce-2018-0591 lai, x., liu, j., shi, q., georgiev, g., wu, g., 2017. driving forces for low carbon technology innovation in the building industry: a critical review. renewable and sustainable energy reviews 74, 299-315. https://doi.org/10.1016/j.rser.2017.02.044 lepage, r., eng, p., higgins, j., finch, g., 2017. moisture uptake testing for clt floor panels in a tall wood building in vancouve, in: conference: 15th canadian conference on building science and technology, at vancouver, bc. vancouver, b.c., canada, p. 17. mjörnell, k., arfvidsson, j., sikander, e., 2011. a method for including moisture safety in the building process. indoor and built environment 21, 583-594. https://doi.org/10.1177/1420326x11428340 öberg, j., wiege, e., 2018. moisture risks with clt-panels subjected to outdoor climate during construction-focus on mould and wetting processes fuktrisker på kl-trä som utsätts för yttre klimat under produktion-fokus på mögel och uppfuktning. kth royal institute of technology, stockholm. ofori, g., 2000. challenges of construction industries in developing countries: lessons from various countries, in: 2nd international conference on construction in developing countries: challenges facing the construction industry in developing countries. 15-17 november 2000, gabarone, pp. 1-13. interior insulation, constructional moisture and thermally efficient building envelope”, institutional research funding grant iut1-15, estonian centre of excellence in zero energy and resource efficient smart buildings and districts, zebe, grant tk146 funded by the european regional development fund. journal of sustainable architecture and civil engineering 2019/2/25 62 about the authors eneli liisma head of quality management department as merko ehitus eesti main research area quality control, building materials address järvevana tee 9g, tallinn 11314, estonia. tel. +372 80 5105 babette liseth kuus site technician as merko ehitus eesti main research area quality control, building materials address järvevana tee 9g, tallinn 11314, estonia tel. +372 80 5105 e-mail: babetteliseth. kuus@merko.ee villu kukk phd candidate tallinn university of technology, department of civil engineering and architecture, nearly zero energy building research group main research area hygrothermal behaviour of clt structures address ehitajate tee 5, tallinn 19086, estonia tel. +3726202403 e-mail: targo. kalamees@taltech.ee targo kalamees professor of building physics tallinn university of technology, department of civil engineering and architecture, nearly zero energy building research group main research area building envelope structures; renovation of buildings; hygrothermal behaviour of buildings structures (computer simulations, laboratory experiments, field studies); moisture safety of buildings; boundary conditions for hygrothermal simulations and experiments; building energy consumption and healthy building design; indoor climate and indoor air quality of residential-, office-, and historic buildings. address ehitajate tee 5, tallinn 19086, estonia tel. +3726202403 e-mail: targo. kalamees@taltech.ee schickhofer, g., flatscher, g., ganster, k., sieder, r., zimmer, s., 2017. a status report from the clt hot spot in europe | austria, in: clt seminar sola city conference center, tokyo. wang, j., 2016. guide for on-site moisture management of wood construction. yle, 2017. more water damage detected at new housing blocks in helsinki. 25 journal of sustainable architecture and civil engineering 2019/2/25 corresponding author: kehl@holzbauphysik.de moisture safety of the construction with vcl using hygrobrid technology received 2019/01/09 accepted after revision 2019/05/02 journal of sustainable architecture and civil engineering vol. 2 / no. 25 / 2019 pp. 25-34 doi 10.5755/j01.sace.25.2.22422 moisture safety of the construction with vcl using hygrobrid technology jsace 2/25 http://dx.doi.org/10.5755/j01.sace.25.2.22422 martin polikarpus siga cover ag, rütmattstrasse 7, ch-6017 ruswil, switzerland daniel kehl büro für holzbau und bauphysik, nixenweg 14, d-04277 leipzig, germany unventilated and green flat roofs with wooden construction and insulation between the rafters are used in new buildings. due to the external vapour-tight construction, such roofs have no drying capacity on the outside. the scope of this study is to assess whereas the wood degradation in the wood or osb caused by wood destroying fungus can take place as this can affect the structural function of the construction. results show, that the 3rd generation moisture variable vapour control layer, which has additional function that the sd-value changes according to the direction of the diffusion, has many application areas. the behaviour of the vapour control layer has a positive effect on the moisture balance of an external vapour-tight green roof. the moisture and direction variable performance of the 3rd generation vapour control layer has also a positive effect on the moisture balance of an external vapour-tight pitched roof. it is important to underline that presented results are valid for central-european climatic conditions. keywords: building physics, diffusion tight flat roof, diffusion tight pitched roof, hygrobrid, moisture variable introduction unventilated and flat green roofs unventilated and green flat roofs with wooden construction and insulation between the rafters are used in new buildings. due to the external vapour-tight construction, such roofs have no drying capacity on the outside. this is a typical application area for a moisture variable vapour control layer, which has a higher diffusion resistance in winter, when the inside air is dry, and a lower diffusion resistance in the summer, when the humidity is re-diffused and the room air is more humid. since flat roofs are a standard in new buildings, the moisture from screed and plaster should also be considered. pitched roofs with vapour-tight underroof the functioning roofs of old buildings can energetically renovated from the inside. in previous times, such roofs were often constructed with a vapour-tight underroof (e.g. bitumen sheeting on wooden framework). therefore, the internal vapour control layer is of particular importance also in this type of construction. journal of sustainable architecture and civil engineering 2019/2/25 26 the scope of the simulations is to assess whereas the wood degradation in the wood or osb caused by wood destroying fungus can take place as this can affect the structural function of the construction. fig. 1 calculated sd-value curves of the 1st and 2nd generation moisture variable vcl-s (left). directional sd-value curves of the 3rd generation vcl – blue curve: room → insulation; red curve – insulation → room (right) methods vapour control layer the simplified glaser method according to din 4108-3: 2014 and sia 180: 2014 is not applicable for external vapour-tight, green flat roofs, and vapour tight pitched roofs in wooden construction with inward laying moisture control layer. in addition, such a simplified method cannot be used to analyse different parameters in terms of building physics. in such cases, hygrothermal simulations could be used (en 15026: 2007; wta 6-2: 2014). the roof types can be examined and analysed using the software delphin 5.9. these analyses will demonstrate the performance of the newly developed 3rd generation vapour control layer with hygrobrid technology (3rd generation mvvcl). the vapour control layer is not only moisture variable but also direction variable, and it is compared in this examination with other moisture variable vapour control layers with small and large spread. moisture variable vapour control layer there are currently many different moisture variable vapour control layers available on the market. the first generation of vapour control layers with moisture variable diffusion resistance has a small spread between high and low diffusion resistance (fig. 1). since then, they have been developed further, so that the 2nd generation vapour control layers have a larger spread of diffusion-equivalent air layer thickness (sd-value) (fig. 1). moisture and direction variable vapour control layer besides the moisture variability, this patented vapour control layer has an additional function – its material properties allow different sd-value at the same ambient air humidity, according to the direction of the diffusion flux. this way, the effect of the moisture variability is strengthened. moreover, the diffusion of the water vapour in the construction is reduced due to the elevated sd-value (fig. 1) at higher room air humidity (e.g. moisture from screed or plaster during construction phase). the presented curves are based on measurements carried out by tu dresden. 27 journal of sustainable architecture and civil engineering 2019/2/25 flat roof external vapour-tight and green flat roof in wooden construction is simulated hygrothermally (table 1). the roof is provided with a sealing (construction site seal) above the osb panel with additional insulation of a further seal. as several studies have determined, construction of green roof has an unfavourable effect on its drying capacity. the section of a flat roof is shown in fig. 2. layer numbers correspond to table 1. table 2 structural building components of the calculated pitched roof table 1 structural building components of the calculated flat roof construction fig. 2 section of flat roof layer number description thickness [mm] thermal conductance [w/(m·k)] vapour resistance [-] 1 green roof – – – 2 roof seal 1.0 2.3 100 000 3 on-roof insulation 120.0 0.028 100 4 bituminous sheeting with aluminium insert 1.0 2.3 1500 000 5 osb panel 22.0 0.13 165 6 mineral fibre insulation cellulose insulation 240.0 240.0 0.035 0.040 1 1.5 7 vapour control layer 0.16 2.3 800-35000 8 air layer (batten) 25.0 0.18 0.46 9 gypsum plasterboard 12.5 0.2 8.3 layer number description thickness [mm] thermal conductance [w/(m·k)] vapour resistance [-] 1 roof covering – red clay tiles 2 air layer (counter batten) 3 bituminous sheeting 2.0 2.3 100 000 4 solid wooden formwork 22.0 0.09 130 5 mineral fibre insulation cellulose insulation 240.0 240.0 0.035 0.040 1 1.5 6 vapour control layer 0.16 2.3 800-35000 7 air layer (batten) 30.0 0.18 0.46 8 gypsum plasterboard 12.5 0.2 8.3 construction calculations pitched roof unventilated and externally vapour-tight pitched roof with ventilated roof covering is simulated hygrothermally (table 2). the roof is provided with an external vapour-tight underroof on solid journal of sustainable architecture and civil engineering 2019/2/25 28 table 4 boundary conditions for the hygrothermal simulations of pitched roofs wooden formwork and represents the classic building standards of the 1960s and 1970s. the first studies have shown (künzel 1998) that the external and internal climate, the inclination of the roof and the orientation are important influencing factors for the drying performance of the roof. convection through leaks is an additional factor to consider. the section of calculated pitched roof is given in fig. 3. layer numbers correspond to table 2. boundary conditions used the results of the hygrothermal simulations are always in connection with the applied boundary conditions (table 3, table 4). parameter description of boundary conditions outdoor climate: holzkirchen humidity reference year orientation: north indoor climate: internal climate according to en iso 13788: / wta 6-2: 2014 20-25 °c and 35-65 % relative air humidity surface transfer coefficient outwards: (convective component) heat transfer resistance: 0,08 m²k/w heat transfer coefficient: 12,5 w/m²k surface transfer coefficient inwards: heat transfer resistance: 0,125 m²k/w heat transfer coefficient: 8 w/m²k short-wave absorption coefficient a: a = 0,6 [-] (künzel 1998) long-wave emissions coefficient ε: ε = 0,3 [-] (künzel 1998) source of humidity airtightness: airtightness class b (q50 = 3 m³/m²h) height of the air column in the building: 10 m moisture load 250g/m2y start/duration of the simulation: 01.10. / 10 15 years to a steady state starting humidity: 20 °c / 80 % relative air humidity (cellulose: 50 %) table 3 boundary conditions for the hygrothermal simulations for flat roofs fig. 3 section of pitched roof parameter description of boundary conditions outdoor climate: holzkirchen humidity reference year indoor climate: internal climate according to en iso 13788: / wta 6-2:2014 20-25 °c and 35-65 % relative air humidity or building moisture surface transfer coefficient inwards: heat transfer resistance: 0,125 m²k/w; heat transfer coefficient: 8 w/m²k source of humidity airtightness: airtightness class b (q50 = 3 m³/m²h) height of the air column in the building: 10 m moisture load 250g/m2y start/duration of the simulation: 01.10. / 10 – 15 years to a steady state starting humidity: 20 °c / 80% relative air humidity (cellulose: 50%) simulation boundary conditions 29 journal of sustainable architecture and civil engineering 2019/2/25 explanation of the boundary conditions outdoor climate: künzel (1998) has shown that with the external vapour-tight pitched roofs, the humidity of the outer wooden framework with the same roof inclination essentially depends on the outside temperature. the colder it is, the bigger the damage to the construction of the building could be. holzkirchen, together with hof, is one of the most critical sites and covers locations with an annual average temperature of at least 6.6 °c (in comparison stockholm and oslo has an annual average temperature of 6.8 °c with annual sun radiation difference of 2-4%). since the climate data set in holzkirchen (reference year for humidity) was of high quality for the simulation, this data set was used. moisture load and convection: the 22 mm thick wood and 22 mm osb is divided into two layers in the simulation: 12 mm and 10 mm. the 10 mm layer is situated towards the inner side of the construction and moisture load of 250g/m2y is applied to this layer. in this way leaks through convection are taken in account. green roof: green roofs have an impact on the hygrothermal performance of the flat roof. as there is no validated material data set for the green roofs in delphin 5.9, the climate data set was generated from temperature and relative air humidity. in addition, the flat roof described above is simulated using wufi® including a 80 mm green roof (single layer substrate). the temperature and relative air humidity above the seal has been recorded and transferred into a climate data set for delphin. the 80 mm layer of green roof is taken from the research project [ibp 2013] of fraunhofer institute for building physics and has been validated on various roofs in europe (leipzig, vienna, holzkirchen, milan). built-in moisture: as the examinations of the fraunhofer institute for building physics show (holm, künzel 1999), the wet masonry walls with outside insulation dry between 2-4 years, depending on the insulation material (mineral fibre and eps). therefore, an assumption is made that the relative room air humidity only adapts to the normal indoor climate in the residential buildings in the course of three years as derived in the study by zirkelbach, holm in 2001 using room simulations. orientation: according to the orientation of the roof, the solar radiation onto the pitched roof is different it is the highest towards the south and lowest towards the north. the pitched roof examined in this study is towards the north direction and is therefore in an unfavourable situation. evaluation criteria for oriented strand board (osb) and wood oriented strand board in case of high material moisture, the strength parameters of osb are reduced. this can lead to both a reduction of the load capacity and the usability (din 68800-2: 2012). this is to comply with the limit value of 18 m-%. according to the standard, it may be temporarily exceeded up to 20 m-%, if it can re-dry within 3 months. safety margin for osb the safety margin is determined by means of the limit value of 18 m-%. in this case, the smallest margin between the osb moisture and the limit value in the steady state is calculated. if the value is negative, the limit is exceeded, if it is positive, then it is not exceeded. definition of the safety margin for osb are shown in fig. 5. in addition to the safety margin of the limit curve, the amplitude of the osb is evaluated. damage cases are known, where a bulge in the construction / pressing apart of the underlying walls appeared due to significant changes of moisture in osb. therefore, it is recommended in wta mb e 6-8: 2015, chapter “usability”, that the humidity fluctuation between summer and winter is to be constructively minimized (e.g. by additional external insulation). journal of sustainable architecture and civil engineering 2019/2/25 30 evaluation criteria for wood for the assessment of wood moisture content, the so-called 20 m-% wood moisture criteria is often used. as stated by kehl (2013), such a limit value is unsuitable for the evaluation of the hygrothermal simulation. in such cases, a detailed demarcation is needed, which couples the height and duration of the humidity with the temperature. for this purpose kehl (2013) derived a limit based on finnish investigations (viitanen, ritschkoff 1991). as a result of the study, no wood degradation took place following 12 months of storing wood samples with inoculated wood-destroying fungi in climatic conditions that lie on the limit value line. fig. 4 limit curve according to [wta e 6-8 2015] for the evaluation of the pore air humidity and temperature under a 10 mm thick wood layer, which may not be exceeded in the daily average fig. 5 example for the definition of the safety margin between the recorded daily average of the wooden composite moisture and the limit value in the 10th year steady state (left). example of the definition of the safety margin for wood between the entered average daily values and the limit curve in the 5th year in steady state (right) since the wood moisture content spreads due to different absorption isotherms in the individual programs, the wood moisture content is not evaluated but rather the relative humidity in the material (pore air humidity) is taken in account. this type of evaluation has proven itself in numerous simulations and can be found in the corresponding regulations (wta mb e 6-8 2015). the temperature and relative pore air humidity in the wood (10 mm thick layer) is averaged over the day and represented in fig. 4. safety margin for wood the safety margin is determined in fig. 5, which shows the border limit and an example of the measured daily values for the 5th year. the smallest distance between the value pairs (temperature / relative pore air humidity in the material) and the limit curve in the steady state are calculated. in case of a negative value, the limit curve is exceeded, it may result in wood degradation by wood-destroying fungi; in case of a positive value it cannot. if the safety margin is very small, it must be observed, whether the long-term humidity level is low. results safety margin with mineral fibre insulation for flat roofs the safety margins of the (osb) moisture when using the different vapour control layers are shown in fig. 6. when using mineral fibre insulation and considering the convection (ldk b, h = 10 m), the 3rd generation mvvcl has a safety margin up to 1.1 m-% compared to other vapour control layers. if the safety margin is negative then it exceeds the limit value. 31 journal of sustainable architecture and civil engineering 2019/2/25 moreover, the humidity fluctuation of an osb panel with 3rd generation mvvcl is lower, 0,8 m-% per year (see fig. 7). due to lower amplitude, the deformations of the osb panel are also reduced. safety margin of moisture building since flat roofs are mainly used in new buildings, the moisture behaviour within the first few years after completion of the building is considered in fig. 7. as already described above, the increased moisture building is taken into account within the first 3 years. although the moisture and direction variable performance of the 3rd generation vcl slightly exceeds the limit (18.2 m-%), the duration of the exceedance is less than 3 months, which is permissible according to din 68800-2. fig. 6 safety margin of an external vapour-tight flat roof with different vapour control layers and mineral fibre insulation. the 3rd generation mvvcl is the only one with a safety margin to the limit value. the others exceed the limit value of 18 m-% fig. 7 humidity fluctuation of the osb panel between summer and winter (amplitude) 1,1% -0,8% -0,2% -1,0% -0,5% 0,0% 0,5% 1,0% 1,5% 3. generation mvvcl 1. generation mvvcl 2. generation mvvcl sa fe ty m ar gi n (m -% ) incl. convection / air humidity according to wta 6-2: 14 safety margin flat roof (mineral fibre) holzkirchen 0,8% 1,7% 1,2% 0,6% 0,8% 1,0% 1,2% 1,4% 1,6% 1,8% a m p lit u d e o s b p a ne l ( m -% ) incl. convection / air humidity according to wta 6-2: 14 amplitude osb panel flat roof (mineral fibre) holzkirchen 18,2% 20,9% 19,5% 16,9% 18,8% 18,2% 0% 5% 10% 15% 20% 25% 3. generation mvvcl 1. generation mvvcl 2. generation mvvclm ax o sb m oi st ur e (m -% ) incl. convection / increased building moisture max osb moisture (mineral wool) holzkirchen 1-3 years steady state the lower the value, the less deformations resulting from it (left). maximum material moisture of the osb panel in the first 3 years following the production (with the estimated building moisture) and the long-term performance. with its moisture and direction variable vapour control layer, the 3rd generation mvvcl shows a strong inclination towards building moisture (right). safety margin for pitched roofs the roof is gradually tilted north, which reduces the solar short-wave radiation onto the roof and thus the re-drying capacity of the building component. the safety margin between the 3rd generation mvvcl and the moisture variable vapour control layer of the 1st and 2nd generation in conjunction with the roof inclination is shown in fig. 8. if the safety margin is very small (yellow area), the data must be analysed more precisely. the steeper the roof inclination is, the lower the level of summer re-drying and thus the safety margin. accordingly, the application area of the 3rd generation mvvcl in case of a north orientation is possible up to a roof inclination of 80° and thus also for steep mansard roofs. journal of sustainable architecture and civil engineering 2019/2/25 32 the moisture variable vapour control layer of the 1st generation at 40° in a steady state has a small safety margin of 1.2 m-% relative to air humidity (fig. 9). however, it exceeds the limit curve in the first year of the simulation. the moisture variable vapour control layer of the 2nd generation can be constructed up to a roof inclination of 60°. if cellulose is used in the roof construction instead of mineral fibre, the pitched roof with all the vapour control layers may only be constructed up to a roof inclination of 40°. in case of a 40° and 60° inclined, north-oriented roof, the safety margin of the fig. 8 safety margin of an external vapourtight pitched roof (north orientation) with different vapour control layers in function of roof inclination (mineral fibre insulation) fig. 9 safety margin of an external vapourtight pitched roof (north orientation) with different vapour control layers in function of roof inclination (left: 40°, right: 60°) fig. 10 evaluation of the pore air humidity/ temperature according to wta-leaflet e 6-8 in 10 mm wooden formwork for 1st, 2nd and 10th year 3rd generation vcl will be again compared with the moisture variable vapour control layer of the 1st generation and the 2nd generation (fig. 9). daily calculated pore air humidity/temperature values for 3rd generation mvvcl and the limit line for mould growth according to wta-leaflet e 6-8 in 10 mm wooden formwork on 1st, 2nd and 10th year are presented on fig. 10 dealing with pitched roofs with mineral fibre insulation, north orientation 60o pitch. delphin calculation results for development of the pore air humidity in a 10 mm thick wooden layer and the corresponding condensing limit value according to wta-leaflet e 6-8 are given in fig. 11. 33 journal of sustainable architecture and civil engineering 2019/2/25 the 3rd generation moisture variable vapour control layer, which has additional function that the sd-value changes according to the direction of the diffusion, has many application areas. the behaviour of the vapour control layer has a positive effect on the moisture balance of an external vapour-tight green roof. even in case of unfavourable conditions, there is still a re-drying capacity. as compared with the moisture variable vapour control layers of the 1st and 2nd generation, it has a high drying potential. the moisture and direction variable performance of the 3rd generation vapour control layer has also a positive effect on the moisture balance of an external vapour-tight pitched roof. even in unfavourable conditions (e.g. 80° north – mineral fibre insulation with convection), a re-drying capacity still exists. as compared to the moisture variable vapour control layer of the 1st and 2nd generation, the vapour control layer has a greater drying potential also in these constructions. it is important to underline that presented results are valid for central-european climatic conditions. authors of this study have conducted numerous simulations for northern-european climate (oslo, tromso, stockholm, helsinki) which will be presented in further research. references fig. 11 development of the pore air humidity in a 10 mm thick wooden layer and the corresponding condensing limit value according to wta-leaflet e 6-8 conclusions din 4108-3. 2014. wärmeschutz und energie-einsparung in gebäuden – teil 3: klimabedingter feuchteschutz – anforderungen, berechnungsverfahren und hinweise für planung und ausführung [thermal insulation and energy savings in buildings – part 3: climate-related moisture protection – requirements, calculation methods and instructions for planning and execution], beuth verlag, berlin 2014 din 68800-2. 2012. holzschutz – teil 2: vorbeugende bauliche maßnahmen im hochbau [wood protection – part 2: preventive structural measures in building construction], beuth-verlag, berlin en 15026. 2007. wärmeund feuchtetechnisches verhalten von bauteilen und bauelementen – bewertung der feuchteübertragung durch numerische simulation [thermal and humid-technical behavior of components and components – evaluation of moisture transmission by numerical simulation], beuth-verlag, berlin en iso 13788. 2013. wärmeund feuchtetechnisches verhalten von bauteilen und bauelementen – raumseitige oberflächentemperatur zur vermeidung kritischer oberflächenfeuchte und tauwasserbildung im bauteilinneren – berechnungsverfahren [thermal and humidity – related behavior of components and constructions – room-side surface temperature to avoid critical surface moisture and condensation in the interior of the component – calculation method], beuth verlag, berlin holm, a.; künzel, h.m. 1999. trocknung von mauerwerk mit wdvs und einfluß auf den wärmedurchgang [drying of masonry with mvvcl and influence on the heat transfer], in: bauklimatisches symposium, dresden ibp 2013. hrsg.: fraunhofer institut für bauphysik, forschungsvorhaben: ermittlung von materialeigenschaften und effektiven übergangsparametern von dachbegrünungen zur zuverlässigen simulation der hygrothermischen verhältnisse in und unter gründächern bei beliebigen nutzungen und unterschiedlichen standorten [research project: determination of material properties and effective transition parameters of green roofs for the reliable simulation of hygrothermal conditions in and under green roofs for any use and different locations], eigenverlag, holzkirchen journal of sustainable architecture and civil engineering 2019/2/25 34 kehl, d. 2013. feuchtetechnische bemessung von holzkonstruktionen nach wta hygrothermische auswertung der anderen art, beitrag in der fachzeitschrift holzbau – die neue quadriga, ausgabe 06-2013 [humidity-related design of timber constructions according to wta hygrothermal evaluation of the other species, article in the journal holzbau the new quadriga, issue 06-2013], kastner verlag, wolnzach künzel, h.m. 1998. bedeutung von klimabedingungen und diffusionseigenschaften für die feuchtesicherheit von altbaudächern, in: berichte aus forschung und praxis festschrift zum 60. geburtstag von karl gertis [importance of climatic conditions and diffusion properties for the moisture safety of old roofs, in: reports from research and practice commemorative publication on the 60th birthday of karl gertis], irb-verlag, stuttgart 1998 sia 180. 2014. schweizerischer ingenieurund architektenverein: sia 180 – wärmeschutz, feuchteschutz und raumklima in gebäuden [swiss association of engineers and architects: sia 180 thermal insulation, moisture protection and indoor climate in buildings], zürich viitanen, h.; ritschkoff, a-c. 1991. brown rot decay in wooden constructions. effect of temperature, humidity and moisture; swedish university of agricultural scienses, department of forest products, report no 222, uppsala wta mb 6-2. 2014. hrsg. wissenschaftlich technische arbeitsgemeinschaft für bauwerkserhaltung und denkmalpflege: merkblatt 6-2: simulation wärmeund feuchtetechnischer prozesse [scientific technical association for building preservation and historic preservation: fact sheet 6-2: simulation of heat and humidity], irb verlag, münchen wta mb e 6-8. 2015. hrsg. wissenschaftlich technische arbeitsgemeinschaft für bauwerkserhaltung und denkmalpflege: merkblatt entwurf 6-8: feuchtetechnische bewertung von holzbauteilen – vereinfachte nachweise und simulation zirkelbach, d.; holm a. 2001. trocknungsverhalten von monolithischen wänden [scientific technical working group for building conservation and historic preservation: leaflet draft 6-8: humidity assessment of timber components simplified evidence and simulation: drying behavior of monolithic walls], in: ibp mitteilung 389, eigenverlag, holzkirchen martin polikarpus deputy head of application engineering north europe siga cover ag, application engineering north europe main research area building physics and material behavior adress rütmattstrasse 7, ch-6017 ruswil, switzerland tel. +41 41 499 69 69 e-mail: martin.polikarpus@siga.swiss about the authors daniel kehl consultant for building physics bü ro für holz bau und bau phy sik main research area building physics and hygrothermal behavior adress ni xen weg 14, 04277 leip zig, germany tel. +49 0341-52941138 e-mail: kehl@holzbauphysik.de 49 journal of sustainable architecture and civil engineering 2018/2/23 *corresponding author: mantas.dobravalskis@ktu.lt potential of harvesting rainwater from vertical surfaces received 2018/09/24 accepted after revision 2018/11/03 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 79-85 doi 10.5755/j01.sace.23.2.21606 potential of harvesting rainwater from vertical surfaces jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.21606 mantas dobravalskis*, paulius spūdys, juozas vaičiūnas, paris fokaides kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania the water supply chain is under increasing stress as urbanisation and population growth is driving more and more people to move to cities. an increasing amount of city planners are now looking for alternative water resources, rainwater being one of them. there are multiple benefits to on-site water collection, storage and use, as proven by multiple published studies and successful projects around the world; however, rainwater harvesting (rwh) has remained a niche technique, not seen as part of the mainstream. one of the reasons for this is that, traditionally, rainwater has only been collected from rooves and other horizontal surfaces, and then transferred and stored in various subsurface holding tanks. this method of rwh is dated and not very effective. furthermore, rainwater is one of the purest water sources, but when collected from horizontal surfaces, it gets polluted with particles that have settled on those surfaces. as a result, rwh in this way can be used only for specific purposes. in order to fully utilise this natural resource, to enable the creation of sustainable cities, we must devise a new method for collecting rainwater. one aspect of rwh that has not yet been deeply explored is collecting it from vertical surfaces. although some abstract studies have already been conducted, concerning water runoff from vertical surfaces, no studies have evaluated the possibility of harvesting and using such water. in this paper, the impacts of different sets of conditions and variables on the performance of rwh systems mounted on vertical surfaces, such as building facades, are compared. in addition, this study aimed to evaluate the potential of such systems to be used in real-world projects around the globe. to accurately measure collected rainwater, an experimental stand was constructed. this stand consisted of a mechanism that allowed the water-collecting surface and its parameters to be changed, whilst also measuring various aspects of the weather and the amount of water that was successfully harvested. the experiments were conducted in both a controlled environment (laboratory) and under real (natural) conditions. the results of this study provide a more accurate evaluation of how vertical rwh systems can be implemented in real-life projects around the globe and show how natural conditions and the surfaces used can change the effectiveness of rwh. keywords: rainwater harvesting, sustainable cities, vertical surfaces, water source, wind driven rain. introduction under real-life conditions, all rain has a horizontal velocity due to wind acting upon rain droplets. such rain is called wind-driven rain (wdr). even though most building facades are completely vertical, rain still hits them due to this reason. this provides an opportunity for collecting such rain from vertical surfaces, allowing it to be used in water supply systems. on the other hand, wdr is not only an opportunity, but also a threat. multiple studies have showed that rainwater can do serious damage to building materials and their longevity (abuku, janssen, roels, 2009; blocken, deromeb, carmeliet, 2013). all porous construction materials can hold a maximum amount of moisture, but when this threshold is reached or exceeded, serious damage journal of sustainable architecture and civil engineering 2018/2/23 50 can occur. frost damage due to expanding water, the discolouration of facade materials and structural degradation are all caused by excess water in facades (kyllingstad et al., 2010). there are multiple benefits to harvesting rainwater from building facades, for example cleaner surface and more unused space when compared to roofs. but there have not yet been meaningful or comprehensive studies in this field. evaluating the wdr harvesting potential from vertical surfaces requires accurate rwh measurement datasets that follow guidelines to guarantee precise and reliable data. such information would also be of use in future studies, and in the development of such wind-driven rwh systems for use in real buildings around the world. this study aimed to precisely measure the amount of rainwater that could be successfully collected from vertical surfaces, such as building facades. to that end, a specialized wdr harvesting stand was developed and manufactured. a first series of experiments was conducted in the laboratory using simulated rain. the experimental stand had the ability to change the angle of the vertical surface by up to 7.5°. both successfully harvested rainwater and runoff were measured. load cells were used as primary parts of the measuring equipment. these can measure mass changes, as times goes by, and allowed us to observe how effective the system was, as well as how the rain intensity impacted the effectiveness of the system. in the methods section, a detailed description of the experimental stand is given, alongside photos and drawings, as well as of the main control unit. this section also contains an explanation of the methodology that was used to analyze the data collected during the experiments. the results section presents the parameters of the simulated rain, the measured rwh data and the results of the data analysis. these results show the percentages of rainwater that can be harvested, of water runoff and of rainwater that splashed off and could not be harvested. methods fig. 1 system used for wind driven rainwater harvesting from vertical surfaces (a -rwh assembly, b base, c – main control unit, d – data logging process) the experimental stand for measuring the rainwater collection rate was constructed. this is shown in fig. 1, and is composed of two main parts – the rwh stand and the main control unit. a) b) c) d) 51 journal of sustainable architecture and civil engineering 2018/2/23 experimental stand the experimental stand for rwh comprises of a rwh assembly(a) and a base(b) (fig. 2). the main purpose of the base was to hold the water-measuring scales(c) and ensure stability of the rwh assembly. the base measured 1000 mm x 970 mm x 300 mm. due to the stand comprising of two parts, the base had two sockets that enabled easy installation of the rwh assembly. each side of the base was covered in aluminum sheeting and cement particleboard. this was required to make sure that the mass measuring equipment in the base would not be exposed to water droplets splashing from the vertical surface of the stand, or from other excess water that had not been harvested. cement particleboard was used to increase the mass of the base, so that it was more stable and could be used outside in windy conditions in the study planned for natural outdoor conditions. fig. 2 experimental stand (a rwh assembly, b – base, c – water scales for harvested rainwater and runoff) fig 2. experimental stand (a rwh assembly, b – base, c – water scales for harvested rainwater and runoff) the rwh assembly imitates a real building facade, with a system for wind-driven rwh. this is illustrated in figure 2. it has additional equipment for transporting the harvested rainwater to measuring devices at the base. this part of the experimental stand was constructed from a hermetic box, with the front side covered with the facade panel being tested. the depth of the box was 58 mm. water that permeated through the facade panel ran down the box and into a gutter that had an outlet hose running to scale 1 – the scale that tracked the mass of harvested rainwater. rainwater runoff that flowed down the panel surface and did not enter the box was collected by another gutter that was mounted on the outside of the box. water from this gutter went to scale 2, which measured rainwater runoff. a section of rwh assembly is shown in figure 3. fig 3. wind driven rainwater harvesting system section also showing ways that rain droplets can act upon falling on the facade panel one architectural panel was tested – a type commonly used in modern architecture, which was supplied by a company that supplies metal facade panels for construction of various buildings. using an existing panel proved that the suggested rwh system could be implemented in various types of buildings without limitations on the design or materials being used. the panel tested was made of expanded metal; its full parameters are shown in table 1. the rwh assembly imitates a real building facade, with a system for wind-driven rwh. this is illustrated in fig. 2. it has additional equipment for transporting the harvested rainwater to measuring devices at the base. this part of the experimental stand was constructed from a hermetic box, with the front side covered with the facade panel being tested. the depth of the box was 58 mm. water that permeated through the facade panel ran down the box and into a gutter that had an outlet hose running to scale 1 – the scale that tracked the mass of harvested rainwater. rainwater runoff that flowed down the panel surface and did not enter the box was collected by another gutter that was mounted on the outside of the box. water from this gutter went to scale 2, which measured rainwater runoff. a section of rwh assembly is shown in fig. 3. fig. 3 wind driven rainwater harvesting system section also showing ways that rain droplets can act upon falling on the facade panel a) b) c) water scales journal of sustainable architecture and civil engineering 2018/2/23 52 one architectural panel was tested – a type commonly used in modern architecture, which was supplied by a company that supplies metal facade panels for construction of various buildings. using an existing panel proved that the suggested rwh system could be implemented in various types of buildings without limitations on the design or materials being used. the panel tested was made of expanded metal; its full parameters are shown in table 1. water was sprayed though a fixed water hose nozzle that was fixed to a tripod so that it could be adjusted easily while still remaining stable when spraying water. all of the experiments where conducted with the water nozzle in the same position. the water nozzle was connected to table 1 parameters of facade panel being tested number. 3 photo table 1. parameters of facade panel being tested number. 3 photo holes scheme hole measurements a = 100mm; b = 34mm panel area, m2 1.0 all holes area, m2 0.659 percentage of holes from all area, % 65.9 water was sprayed though a fixed water hose nozzle that was fixed to a tripod so that it could be adjusted easily while still remaining stable when spraying water. all of the experiments where conducted with the water nozzle in the same position. the water nozzle was connected to the city water supply by a hose. the nozzle valve was set to one position, and kept the same for all experiments. only the main water supply valve was closed and opened during the experiments. for the water storage, two plastic boxes were used. each of these could hold up to 40 l of water. a special pipe fitting was fixed at the top of the box to allow water from the gutters to flow into it. at the base of each box, a metal end cap was fitted for easy and fast emptying of the boxes. main control unit the main control unit was constructed from off-the-shelf components. arduino was selected as the main controller of the system that all other components were connected to. a layout of main control unit components is shown in figure 4. the system used two separate scales – scale 1 to measure the weight of the rainwater that was successfully harvested during the experiment, and scale 2 that measured the runoff water from the rwh surface (facade panel). fig 4. main control unit schematic both scales had identical construction and components. as the base for the scale, modular metal brackets were used that were put together using rivets. the main parts of the scales were the load cells. due to their wide availability and high accuracy, strain-gauge-type load cells were selected. each cell had a maximum capacity of 10 kg. in order to achieve the required scale capacity, multiple load cells were used per scale. in order to accurately read the changes in the electrical signals generated by the deforming load cell, specialized hx711 amplifiers were used. the amplified signal was measured by the arduino microcontroller, and then was interpreted as mass. the technical specifications of the load cells used are shown in table 2. table 2. technical specifications of load cells that are used in scales capacity kg 10 holes scheme table 1. parameters of facade panel being tested number. 3 photo holes scheme hole measurements a = 100mm; b = 34mm panel area, m2 1.0 all holes area, m2 0.659 percentage of holes from all area, % 65.9 water was sprayed though a fixed water hose nozzle that was fixed to a tripod so that it could be adjusted easily while still remaining stable when spraying water. all of the experiments where conducted with the water nozzle in the same position. the water nozzle was connected to the city water supply by a hose. the nozzle valve was set to one position, and kept the same for all experiments. only the main water supply valve was closed and opened during the experiments. for the water storage, two plastic boxes were used. each of these could hold up to 40 l of water. a special pipe fitting was fixed at the top of the box to allow water from the gutters to flow into it. at the base of each box, a metal end cap was fitted for easy and fast emptying of the boxes. main control unit the main control unit was constructed from off-the-shelf components. arduino was selected as the main controller of the system that all other components were connected to. a layout of main control unit components is shown in figure 4. the system used two separate scales – scale 1 to measure the weight of the rainwater that was successfully harvested during the experiment, and scale 2 that measured the runoff water from the rwh surface (facade panel). fig 4. main control unit schematic both scales had identical construction and components. as the base for the scale, modular metal brackets were used that were put together using rivets. the main parts of the scales were the load cells. due to their wide availability and high accuracy, strain-gauge-type load cells were selected. each cell had a maximum capacity of 10 kg. in order to achieve the required scale capacity, multiple load cells were used per scale. in order to accurately read the changes in the electrical signals generated by the deforming load cell, specialized hx711 amplifiers were used. the amplified signal was measured by the arduino microcontroller, and then was interpreted as mass. the technical specifications of the load cells used are shown in table 2. table 2. technical specifications of load cells that are used in scales capacity kg 10 hole measurements a = 100mm; b = 34mm panel area, m2 1.0 all holes area, m2 0.659 percentage of holes from all area, % 65.9 the city water supply by a hose. the nozzle valve was set to one position, and kept the same for all experiments. only the main water supply valve was closed and opened during the experiments. for the water storage, two plastic boxes were used. each of these could hold up to 40 l of water. a special pipe fitting was fixed at the top of the box to allow water from the gutters to flow into it. at the base of each box, a metal end cap was fitted for easy and fast emptying of the boxes. main control unit the main control unit was constructed from off-the-shelf components. arduino was selected as the main controller of the system that all other components were connected to. a layout of main control unit components is shown in fig. 4. the system used two separate scales – scale 1 to measure the weight of the rainwater that was successfully harvested during the experiment, and scale 2 that measured the runoff water from the rwh surface (facade panel). both scales had identical construction and components. as the base for the scale, modular metal brackets were used that were put together using rivets. the main parts of the scales were the load cells. due to their wide availability and high accuracy, strain-gauge-type load cells were selected. each cell had a maximum capacity of 10 kg. in order to achieve the required scale capacity, multiple load cells were used per scale. in order to accurately read the changes in the electrical fig. 4 main control unit schematic table 1. parameters of facade panel being tested number. 3 photo holes scheme hole measurements a = 100mm; b = 34mm panel area, m2 1.0 all holes area, m2 0.659 percentage of holes from all area, % 65.9 water was sprayed though a fixed water hose nozzle that was fixed to a tripod so that it could be adjusted easily while still remaining stable when spraying water. all of the experiments where conducted with the water nozzle in the same position. the water nozzle was connected to the city water supply by a hose. the nozzle valve was set to one position, and kept the same for all experiments. only the main water supply valve was closed and opened during the experiments. for the water storage, two plastic boxes were used. each of these could hold up to 40 l of water. a special pipe fitting was fixed at the top of the box to allow water from the gutters to flow into it. at the base of each box, a metal end cap was fitted for easy and fast emptying of the boxes. main control unit the main control unit was constructed from off-the-shelf components. arduino was selected as the main controller of the system that all other components were connected to. a layout of main control unit components is shown in figure 4. the system used two separate scales – scale 1 to measure the weight of the rainwater that was successfully harvested during the experiment, and scale 2 that measured the runoff water from the rwh surface (facade panel). fig 4. main control unit schematic both scales had identical construction and components. as the base for the scale, modular metal brackets were used that were put together using rivets. the main parts of the scales were the load cells. due to their wide availability and high accuracy, strain-gauge-type load cells were selected. each cell had a maximum capacity of 10 kg. in order to achieve the required scale capacity, multiple load cells were used per scale. in order to accurately read the changes in the electrical signals generated by the deforming load cell, specialized hx711 amplifiers were used. the amplified signal was measured by the arduino microcontroller, and then was interpreted as mass. the technical specifications of the load cells used are shown in table 2. table 2. technical specifications of load cells that are used in scales capacity kg 10 signals generated by the deforming load cell, specialized hx711 amplifiers were used. the amplified signal was measured by the arduino microcontroller, and then was interpreted as mass. the technical specifications of the load cells used are shown in table 2. all load cells are similar but have minor differences due to the manufacturing process. in order to accurately measure weight, all of the load cells needed to be calibrated, which was done by special 53 journal of sustainable architecture and civil engineering 2018/2/23 table 2 technical specifications of load cells that are used in scales capacity kg 10 safe overload %fs 120 ultimate overload %fs 150 combined error %fs ±0.05 non-linearity %fs ±0.05 repeatability %fs ±0.03 creep %fs/3min ±0.05 operating temperature range °c -10 +55 code. this code allowed a calibration factor to be set for each load cell individually. tests were performed using known-mass objects to test the accuracy of each scale. the primary results showed inaccuracies of up to 2%. all the data processing and collecting was performed by an arduino mega board, which is an open-source development board that allows the combination and use of different kinds of sensors and devices. all the load cell outputs were connected to arduino after passing through amplifiers. the resistance readings of the load cells were then interpreted as mass values. as there were multiple load cells per scale, several values were added to get a complete reading from each scale. a safety mechanism was also implemented to warn the user when the scales were close to being overloaded, as overloading load cells makes them deform past their plasticity, making further measurements unacceptable. data from the scales needed to be transferred to a computer for further analysis. a serial port connection was established between a computer and the microcontroller using arduino ide software. to make the data easy to work with, and to perform the required calculations, it was transferred in real time straight into microsoft excel. this was done by using specialized software called plx-daq. mass and accurate times were tracked. the main control unit also had an sd card slot implemented. this was used as a backup, so that even if the computer was not functioning, all of the information would still be stored on the sd card and could later be imported to the computer. to accurately track time, it was collected from a real-time clock (rtc). thanks to having the exact time attached to the data being collected, the data was very easy to work with and analyze later. this functionality will be very helpful in experiments conducted under real (natural) conditions. this will allow data gathered by our experimental stand to be easily compared with weather station data. for the laboratory experiments, manual water emptying was used. for experiments conducted outside, arduino was also connected to relays that would control the water management system that empties the water tanks automatically once they were full, or when it stopped raining. this made this system fully automated – a good solution for long-term experiments under real (natural) conditions. experiment description all experiments in the first phase of the study were conducted in the laboratory, under the same conditions. no wind was used during the experiments, but angle of the water flow hitting the panel was set so it simulates winds effects on rain. the experimental stand was mounted in place. the water nozzle stand was placed 95 cm from the facade panel. the angle of the water droplets hitting the facade panel were calculated to be between 50° and 65°. because of the type of water nozzle used, different areas of droplets were hitting the facade at different angles (fig. 5). the water supply was set to one position, and all of the tests experienced the same intensity of simulated rain. the rain pattern hitting the facade panel can be seen in fig. 5. the area of rain spatter was journal of sustainable architecture and civil engineering 2018/2/23 54 approximately sw = 0.76 m 2. sd = 0.24 m 2 was the area that was not hit by any of the water during the experiments. the nozzle was set in this way to make sure that 100% of the water sprayed hit the facade. this way, the amount of water that splashed off the facade, and so did not end up in in the rwh system, could be calculated. firstly, experiments using fully vertical surfaces were conducted. four experiments, lasting from 1:00 to 3:30 minutes, were conducted. after each experiment, the water tanks were manually emptied, then everything was reset to the starting position, and the next experiment was conducted. this was done with all the panels. two more experiments were conducted with the experimental stand set at an angle. the first angle tested was 2.5°, and then 7.5°. all data from the tests were transferred, in real time, from the main control unit to a computer, and saved in microsoft excel. data was collected each second. after all the data was collected, it was used to analyze the effectiveness of the system. data analysis the experimental stand collected and measured three components of the rainwater (fig. 3) – harvested rainwater (qharv.), water runoff (qrunoff) and water that had splashed off the facade panel (qsplash). the amount of water that had splashed off was calculated by subtracting the harvested rainwater and runoff water mass from the total water amount that was sprayed on to the experimental stand. the total water mass that was sprayed on to the facade was calculated by performing an additional test on the spray nozzle. for a measured amount of time, water was sprayed into a bucket, then the amount of water that was collected during that time period was measured. chronometer and one of the scales from the experimental stand were used for these measurements. calculations were then made to determine the mass of water that was sprayed on to the rwh experimental stand in 1 second. to find out the total water quantity sprayed during each test, a multiplication of the test duration and the rain intensity was made. with this information, all further calculations that were needed to evaluate the effectiveness of this rwh system could be made. the main results we were looking for were the amount of water that was harvested, runoff or splashed. all of these components of the rwh were calculated in both quantity in liters and as a percentage of all water that was sprayed on to the surface. fig. 5 a) water hitting panel pattern; b) water droplets hitting facade panel angles fig 5 a) water hitting panel pattern; b) water droplets hitting facade panel angles firstly, experiments using fully vertical surfaces were conducted. four experiments, lasting from 1:00 to 3:30 minutes, were conducted. after each experiment, the water tanks were manually emptied, then everything was reset to the starting position, and the next experiment was conducted. this was done with all the panels. two more experiments were conducted with the experimental stand set at an angle. the first angle tested was 2.5°, and then 7.5°. all data from the tests were transferred, in real time, from the main control unit to a computer, and saved in microsoft excel. data was collected each second. after all the data was collected, it was used to analyze the effectiveness of the system. data analysis the experimental stand collected and measured three components of the rainwater (fig. 3) – harvested rainwater (qharv.), water runoff (qrunoff) and water that had splashed off the facade panel (qsplash). the amount of water that had splashed off was calculated by subtracting the harvested rainwater and runoff water mass from the total water amount that was sprayed on to the experimental stand. the total water mass that was sprayed on to the facade was calculated by performing an additional test on the spray nozzle. for a measured amount of time, water was sprayed into a bucket, then the amount of water that was collected during that time period was measured. chronometer and one of the scales from the experimental stand were used for these measurements. calculations were then made to determine the mass of water that was sprayed on to the rwh experimental stand in 1 second. to find out the total water quantity sprayed during each test, a multiplication of the test duration and the rain intensity was made. with this information, all further calculations that were needed to evaluate the effectiveness of this rwh system could be made. the main results we were looking for were the amount of water that was harvested, runoff or splashed. all of these components of the rwh were calculated in both quantity in liters and as a percentage of all water that was sprayed on to the surface. a) b) results during the experiments, the harvested and runoff rainwater were constantly monitored. the results showed stability and linear growth, as plotted in fig. 6. all four experiments showed similar water mass growth rate with on average only 3% difference between all the experiments, so it can be concluded that the data was collected accurately, and no errors occurred during the experiments. 55 journal of sustainable architecture and civil engineering 2018/2/23 data was collected from the moment the water supply valve was opened to the moment it was closed. due to air in the system, and the consequent unstable water flow at the beginning and end of the experiments, data that were not stable were removed from datasets. the amount of data deleted depended on each experiment. only data with stable rainwater mass growth were used. the simulated rain intensity was calculated using the method described above. after spraying all of the water into a bucket for 7.68 seconds, 870 g of water had been collected. this amount of water was chosen because of limitation of our water tank used for measuring it. this experiment showed that the water nozzle sprayed 0.113 kg of water each second. this equal to 0.14mm/ (s*m2) rain intensity. such rain is classified as very violent rain and is an extreme case. in nature such rain intensity only happens for very short spans of time. expanded stainless steel facade panel results the expanded metal facade panel was perforated, with 66% of the area comprising perforations. calculations were made based on both the full dataset and for random, short time periods fig. 6 amount of water harvested during 4 experiments that were conducted in this study (facade panel vertical) results during the experiments, the harvested and runoff rainwater were constantly monitored. the results showed stability and linear growth, as plotted in figure 6. all four experiments showed similar water mass growth rate with on average only 3% difference between all the experiments, so it can be concluded that the data was collected accurately, and no errors occurred during the experiments. fig 6. amount of water harvested during 4 experiments that were conducted in this study (facade panel vertical) data was collected from the moment the water supply valve was opened to the moment it was closed. due to air in the system, and the consequent unstable water flow at the beginning and end of the experiments, data that were not stable were removed from datasets. the amount of data deleted depended on each experiment. only data with stable rainwater mass growth were used. the simulated rain intensity was calculated using the method described above. after spraying all of the water into a bucket for 7.68 seconds, 870 g of water had been collected. this amount of water was chosen because of limitation of our water tank used for measuring it. this experiment showed that the water nozzle sprayed 0.113 kg of water each second. this equal to 0.14mm/(s*m2) rain intensity. such rain is classified as very violent rain and is an extreme case. in nature such rain intensity only happens for very short spans of time. expanded stainless steel facade panel results the expanded metal facade panel was perforated, with 66% of the area comprising perforations. calculations were made based on both the full dataset and for random, short time periods during the test. these were compared in order to ensure that the results were accurate and stable throughout the duration of the experiments. the main results are listed in table 3. table 3. results when facade panel is vertical duration of experiment (s): 141 rainwater harvested (qharv.): 66.44% rainwater runoff (qrunoff): 20.96% all rainwater sprayed (qrain): 100% harvested rainwater + runoff (qharv.+qrunoff): 87.40% splashed off rainwater (qsplash): 12.60% as we can see from the table 3, results show that 66.44% of all rainwater that hit the facade was successfully harvested when panel was vertical. 20.96% of all rainwater can also be potentially harvested by using external gutter that collects runoff water from the facade. finally, less than 13% of all rainwater was not harvested and have splashed of the facade panel past the external gutter that is collecting facade runoff water. table 3 results when facade panel is vertical duration of experiment (s): 141 rainwater harvested (qharv.): 66.44% rainwater runoff (qrunoff): 20.96% all rainwater sprayed (qrain): 100% harvested rainwater + runoff (qharv.+qrunoff): 87.40% splashed off rainwater (qsplash): 12.60% during the test. these were compared in order to ensure that the results were accurate and stable throughout the duration of the experiments. the main results are listed in table 3. as we can see from the table 3, results show that 66.44% of all rainwater that hit the facade was successfully harvested when panel was vertical. 20.96% of all rainwater can also be potentially harvested by using external gutter that collects runoff water from the facade. finally, less than 13% of all rainwater was not harvested and have splashed of the facade panel past the external gutter that is collecting facade runoff water. angles impact on effectiveness of vertical rainwater harvesting system additional experiments were conducted to analyze the impact of the angle of the facade on the effectiveness of the rwh system. two additional angles were tested – 2.5° and journal of sustainable architecture and civil engineering 2018/2/23 56 7.5°. both angles were tested once. the period of these experiments was 2:30 minutes for each angle. no other parameters were changed, either in the experimental stand or the methodology. the results are compared in table 4. as can be seen from fig. 7, by increasing the angle, the percentage of harvested water also grew. this proved that the facade angle could have a significant impact on the effectiveness of such a system, even though completely vertical facades collects up to 87% of all rainwater. table 4 angles impact on effectiveness on rwh system 2.5° duration of experiment (s): 168 rainwater harvested(qharv.): 71.58% rainwater runoff(qrunoff): 20.88% all rainwater sprayed(qrain): 100% harvested rainwater + runoff(qharv.+qrunoff): 92.44% splashed off rainwater(qsplash): 7.54% 7.5° duration of experiment (s): 147 rainwater harvested(qharv.): 79.72% rainwater runoff(qrunoff): 14.98% all rainwater sprayed(qrain): 100% harvested rainwater + runoff(qharv.+qrunoff): 94.70% splashed off rainwater(qsplash): 5.30% fig. 7 comparison of different facade angles angles impact on effectiveness of vertical rainwater harvesting system additional experiments were conducted to analyze the impact of the angle of the facade on the effectiveness of the rwh system. two additional angles were tested – 2.5° and 7.5°. both angles were tested once. the period of these experiments was 2:30 minutes for each angle. no other parameters were changed, either in the experimental stand or the methodology. the results are compared in table 4. as can be seen from figure 7, by increasing the angle, the percentage of harvested water also grew. this proved that the facade angle could have a significant impact on the effectiveness of such a system, even though completely vertical facades collects up to 87% of all rainwater. table 4. angles impact on effectiveness on rwh system 2.5° duration of experiment (s): 168 rainwater harvested(qharv.): 71.58% rainwater runoff(qrunoff): 20.88% all rainwater sprayed(qrain): 100% harvested rainwater + runoff(qharv.+qrunoff): 92.44% splashed off rainwater(qsplash): 7.54% 7.5° duration of experiment (s): 147 rainwater harvested(qharv.): 79.72% rainwater runoff(qrunoff): 14.98% all rainwater sprayed(qrain): 100% harvested rainwater + runoff(qharv.+qrunoff): 94.70% splashed off rainwater(qsplash): 5.30% fig 7. comparison of different facade angles angles impact on effectiveness of vertical rainwater harvesting system additional experiments were conducted to analyze the impact of the angle of the facade on the effectiveness of the rwh system. two additional angles were tested – 2.5° and 7.5°. both angles were tested once. the period of these experiments was 2:30 minutes for each angle. no other parameters were changed, either in the experimental stand or the methodology. the results are compared in table 4. as can be seen from figure 7, by increasing the angle, the percentage of harvested water also grew. this proved that the facade angle could have a significant impact on the effectiveness of such a system, even though completely vertical facades collects up to 87% of all rainwater. table 4. angles impact on effectiveness on rwh system 2.5° duration of experiment (s): 168 rainwater harvested(qharv.): 71.58% rainwater runoff(qrunoff): 20.88% all rainwater sprayed(qrain): 100% harvested rainwater + runoff(qharv.+qrunoff): 92.44% splashed off rainwater(qsplash): 7.54% 7.5° duration of experiment (s): 147 rainwater harvested(qharv.): 79.72% rainwater runoff(qrunoff): 14.98% all rainwater sprayed(qrain): 100% harvested rainwater + runoff(qharv.+qrunoff): 94.70% splashed off rainwater(qsplash): 5.30% fig 7. comparison of different facade angles 57 journal of sustainable architecture and civil engineering 2018/2/23 although accurate data was collected and analysed, further studies are needed that will analyse how such a system will work under real (natural) conditions. this study only tested the situation where water droplets were hitting a facade panel with no horizontal angle, only vertical angle was used to simulate winds effect. under real conditions, a building’s facade angle is rarely perpendicular to the angle of the wind. this might have a significant impact on the effectiveness of this system, as more droplets need to hit the surface of the panel, rather than going straight through the perforations. furthermore, our simulated rain intensity was very high and rarely occurs in nature. additional experiments with lower rain intensity are required to evaluate if it has any significant impact on the effectiveness of the rwh system. no tests have yet been performed using wind. wind has a big impact on the speed and angle of the droplets. according to literature our experiments used an angle close to the one that occurs under real conditions during very windy rain. in order to fully analyse such a system, studies to evaluate the wind impact are also needed. consequently, experiments with variable winds are needed, as well as tests that evaluate how wind gusts impact the amount of rainwater that is harvested. rain is highly dynamic, with a lot of variables, many of which could have a significant impact on the suggested vertical rwh system, so a lot of work is still left to do to fully evaluate such systems. discussion conclusions acknowledgment based on data analysis conducted after all the experiments, the following main conclusions can be made: _ wind driven rain harvesting system mounted on vertical facades can collect up to 66% off all rainwater that hits the panel when water flow is 0.113 l/s and water droplets hit the panel between 50° and 65° _ when rain droplets hit the panel between 50° and 65° with 0.113 l/s water flow, up to 21% of water runoffs the facade panel surface and can still be collected using external gutters _ only 12.6% of water on average splashes off the facade and can’t be harvested when it hits the panel between 50° and 65° with water flow of 0.113 l/s _ increasing angle of the facade panels also increases the effectiveness of the rwh system. when facade panels were angled at 7.5° systems effectiveness reached 80%. the authors are indebted to uab “morionis” for the supply of architectural panels that were employed for the purpose of this study. the authors are also thankful to uab “šilnuta” for the supply of materials for the construction of the experimental stand’s frame. references a. kubilay, d. derome, b. blocken, j. carmeliet, wind-driven rain on two parallel wide buildings: field measurements and cfd simulations. journal of wind engineering and industrial aerodynamics, 2015; volume 146: 11-28. https://doi.org/10.1016/j. jweia.2015.07.006 b. blocken, d. derome, j. carmeliet. rainwater runoff from building facades: a review. building and environment, 2013; volume 60: 339-361. https://doi. org/10.1016/j.buildenv.2012.10.008 b. blocken, j. carmeliet. a review of wind-driven rain research in building science. journal of wind engineering and industrial aerodynamics, 2004; volume 92, issue 13: 1079-1130. https://doi. org/10.1016/j.jweia.2004.06.003 kyllingstad, s. thiis, t. flø, a. potac.). climate, environment and frost damage of architectural heritage. 2010; 10.1201/b10428-233. m. abuku, h. janssen, s. roels, impact of wind-driven rain on historic brick wall buildings in a moderately cold and humid climate: numerical analyses of mould growth risk, indoor climate and energy consumption. energy and buildings, 2009; volume 41, issue 1: 101110. https://doi.org/10.1016/j.enbuild.2008.07.011 journal of sustainable architecture and civil engineering 2018/2/23 58 s. angrill, a. petit-boix, t. morales-pinzón, a. josa, j. rieradevall, x. gabarrell. urban rainwater runoff quantity and quality – a potential endogenous resource in cities?. journal of environmental management, 2017; volume 189: 14-21. https://doi. org/10.1016/j.jenvman.2016.12.027 paris fokaides chief researcher kaunas university of technology, faculty of civil and environmental engineering main research area sustainable energy in the built environment address studentu st. 48, lt-51367 kaunas, lithuania tel. +35799793207 e-mail: paris.fokaides@ktu.lt villarreal, edgar & dixon, andrew. analysis of a rainwater collection system for domestic water supply in ringdansen, norrkoping, sweden. building and environment, 2005; 40: 1174-1184. https:// doi.org/10.1016/j.buildenv.2004.10.018 mantas dobravalskis student kaunas university of technology, faculty of civil engineering and architecture main research area rain water harvesting, water resources, sustainable development address studentu st. 48, lt-51367 kaunas, lithuania tel. +37060366536 e-mail: mantas. dobravalskis@ktu.lt paulius spūdys student kaunas university of technology, faculty of civil engineering and architecture main research area rain water harvesting, water resources, hvac systems address studentu st. 48, lt-51367 kaunas, lithuania tel. +37063665869 e-mail: p.spudys@gmail.com juozas vaičiūnas lecturer kaunas university of technology, department of civil engineering and architecture competences center main research area water resources, water supply and disposal systems, hydronic performance of hvac systems, renewable energy, structural stability of buildings. address studentu st. 48, lt-51367 kaunas, lithuania tel. +37061556760 e-mail: juozas. vaiciunas@ktu.lt about the authors journal of sustainable architecture and civil engineering 2019/1/24 36 *corresponding author: jaanus.hallik@taltech.ee development of airtightness of estonian wooden buildings received 2018/12/11 accepted after revision 2019/02/07 journal of sustainable architecture and civil engineering vol. 1 / no. 24 / 2019 pp. 36-43 doi 10.5755/j01.sace.24.1.22167 development of airtightness of estonian wooden buildings jsace 1/24 http://dx.doi.org/10.5755/j01.sace.24.1.22167 jaanus hallik* tallinn university of technology, department of civil engineering and architecture, nearly zero energy buildings research group, ehitajate tee 5, tallinn 19086, estonia sense oü, estonia targo kalamees tallinn university of technology, department of civil engineering and architecture, nearly zero energy buildings research group, ehitajate tee 5, tallinn 19086, estonia introduction the field measurements of airtightness in estonian detached and apartment buildings conducted between 2003 – 2017 were combined into a large dataset for further analysis. the buildings were classified based on building structure, number of storeys, year of construction, energy classification and compactness factors. a subset with all wooden buildings (313 in total) was statistically analysed to determine the average (median) air leakage rates at 50 pa and tested (kruskal-wallis test with post-hoc conover test) for significant differences within the grouping factors. as expected, the median air leakage (q50) of older buildings between 10.7 and 13.9 m3/(hm2) has decreased to 1.1 m3/(hm2) after the minimum requirements for energy efficiency have taken effect. a more detailed analysis on newer buildings showed that quality of the workmanship combining systematic measurement routines as well as prefabrication, yields significantly lower median air leakages compared to on-site construction. the buildings with better energy classification targets also achieved lower median air leakages compared to buildings designed to meet minimum requirements. further analysis showed significant differences between buildings with lightweight timber construction and those with log construction. this can be due to fact that the airtightness has been predominantly measured in prefabricated buildings compared to on-site building technology. surprisingly, the analysis showed no significant difference between buildings with a different compactness factor or a different number of storeys. for use in energy calculations, the base values of air leakage rates for each group are calculated and presented accounting for variation of measurements. keywords: airtightness, air leakage, pressurisation test. a well-insulated, airtight and thermal bridge free building envelope is a key factor for nearly zero energy buildings (nzeb) that becomes mandatory from year 2021. minimising heat losses and combining a thermally optimised building envelope with the passive use of solar energy allows a significant reduction in the heat load and heating energy demand of residential buildings. however, increased insulation thickness in timber constructions creates a serious risk of moisture accumulation inside the construction and deterioration of the building structure if the air leakages are not minimised or avoided. this is especially important in the case of timber construction where the materials are more sensitive to extensive moisture and deterioration. in estonia, lightweight timber-frame envelopes are common for single-family detached houses. today timber structures have become more and more common for apartment buildings and non-res37 journal of sustainable architecture and civil engineering 2019/1/24 idential buildings. structures built from timber logs have been historically very common and are still used for some projects. it is expected that the air-tightness of the building envelope has been improved over the years, especially after the minimum requirements for energy efficiency have been set by legislation. however, several publications seem to conclude that the overall air leakage of the building envelope, even in modern buildings, depends mostly on the building quality and on subsequent factors that affect the building quality (mortensen and bergsøe 2017, colijn et.al 2017, kalamees 2007). for example, the number of storeys, compactness of the building volume etc has been shown to increase the complexity of the work needed to achieve the necessary air-tightness. there have been attempts to estimate the air-tightness of the building envelope without measuring, based on component measurements and subsequent calculations, but no reliable method for estimation has been found (relander et.al 2012). this means that in the design phase, or when calculating the energy use of existent buildings with no means of direct measurements, the statistical average values for different building techniques, construction types and different time frames have to be used. the average air-tightness of existing building stock and the variation within subgroups can be different in different countries as the building process and quality assurance measures are different. in this study a large number of air tightness measurements of estonian wooden buildings are statistically analysed to determine the average (median) air leakage rates at 50 pa and tested for significant differences within the grouping factors related to building complexity and quality assurance. additionally, the base values of air leakage are calculated including the effect of variation within the measured groups. methods studied buildings the database of air leakages was combined based on the results of different measurements carried out between 2003 and 2017 (in total 522 buildings). the subset of all wooden buildings (in total 313 buildings) were used for further analysis. the buildings were classified based on building structure (log houses versus lightweight timber frame), the number of storeys (single-storey versus multi-storey), year of construction (built before 1945, built between 1946-1994, built between 1995-2008, built since 2009), energy classification (energy classes a and b versus minimum requirements) and compactness factors (envelope area ratio to volume and envelope area ratio to floor area). additionally, those companies (producers or building companies) with 5 or more measurements were grouped to analyse the effect of systematic measurements on them. for all buildings built since 2009 an additional grouping based on production technology was described to compare on-site building practice to prefabrication for lightweight timber construction, and hand-made building logs to prefabricated building logs for log-houses. the prefabrication level for lightweight timber construction differs between different companies. for volumetric modules the building envelope is typically finished internally and externally and air-tightness is controlled with vapour control membranes separately for each module. prefabricated separate roof and wall elements are typically structurally complete but the internal finishing layers and external cladding are completed on-site allowing for additional taping to connect the vapour control membranes between the separate elements. for both production types the vapour control layer (polyethylene sheet) is used on the interior side of the load bearing structures (fig. 1). for log houses the prefabricated glulam timber logs are assembled on-site and typically no additional insulation nor separate air tightness layers are used. the energy performance requirements of those buildings are fulfilled through more efficient heating system and well insulated lightweight roof structure with similar vapour control membrane for air tightness. for glulam log structures with thickness less than 200mm an additional external insulation layer with timber frame in combination with wind-barrier layer, ventilated cavity and cladding is used for better energy performance. measurements the air leakage measurements were carried out using a standardised pressurisation test according to method b (the test of the building envelope where all the intentional openings (for natujournal of sustainable architecture and civil engineering 2019/1/24 38 ral and mechanical ventilation) shall be sealed, the doors, windows and trapdoors being closed) described in en iso 9972:2015 and en 13829:2001. the air tightness of the building envelope was tested in a range of pressure differences between 10 pa and 60 pa and reported with a standardised pressure of 50 pa. at an air flow rate of 50 pa the pressure difference (v50), the air leakage rate (q50), and air change rate (n50) were calculated by dividing the measured air flow rate by the external envelope area or by the internal volume of the building respectively. for all buildings, a depressurisation test was carried out to test the airtightness of the building envelope. for some buildings an additional pressurisation test was carried out to measure air leakage in reversed pressure conditions. for these buildings, the average leakage rate and other relevant test results were calculated as arithmetic means. statistical analysis the preliminary analysis of the data showed that the distribution of the measured air leakage (q50) data is non-normal. because of this, the median value and 0.16 / 0.84 quantiles were used to describe the distribution within the different subsets of the data and the non-parametric kruskal-wallis rank test was used to determine statistical differences between different groups of the measured data. in case of significant difference, a subsequent pairwise comparison of subsets was carried out using a post-hoc conover test. for the analysis, the statistical analysis software r (version 3.5.1) was used with several add-on packages to allow non-parametric analysis and visualisation. along with median values, the mean value of air leakage rate (q50,mean) and standard deviation (σq50) of all groups were calculated to allow the estimation of base value of air leakage rate (q50,base) for different groups of buildings. calculation of the base value the base value of air leakage rate was calculated according to the method described in the finnish quality assurance manual for airtightness of building envelope [rt 80-10974, 2009]. the calculated base value depends on the group size and the variation within the group, so that 75 percent of the measured buildings will be below the base value with a confidence interval of 84 percent in the case of normal distribution of the means. the base value is calculated according to equation 1 as follows. q50,base = q50,mean + 0.674 ∙ σq50 + σq50 : √n (1) where: q50,base – estimated base value of air leakage rate (m 3/(hm2)); q50,mean – measured value of mean air leakage rate of the group considered (m3/(hm2)); σq50 – standard deviation of mean air leakage rate of the group considered (m3/(hm2)); n – number of measured buildings in the group considered. even in modern buildings, depends mostly on the building quality and on subsequent factors that affect the building quality (mortensen and bergsøe 2017, colijn et.al 2017, kalamees 2007). for example, the number of storeys, compactness of the building volume etc has been shown to increase the complexity of the work needed to achieve the necessary air-tightness. there have been attempts to estimate the airtightness of the building envelope without measuring, based on component measurements and subsequent calculations, but no reliable method for estimation has been found (relander et.al 2012). this means that in the design phase, or when calculating the energy use of existent buildings with no means of direct measurements, the statistical average values for different building techniques, construction types and different time frames have to be used. the average air-tightness of existing building stock and the variation within subgroups can be different in different countries as the building process and quality assurance measures are different. in this study a large number of air tightness measurements of estonian wooden buildings are statistically analysed to determine the average (median) air leakage rates at 50 pa and tested for significant differences within the grouping factors related to building complexity and quality assurance. additionally, the base values of air leakage are calculated including the effect of variation within the measured groups. methods studied buildings the database of air leakages was combined based on the results of different measurements carried out between 2003 and 2017 (in total 522 buildings). the subset of all wooden buildings (in total 313 buildings) were used for further analysis. the buildings were classified based on building structure (log houses versus lightweight timber frame), the number of storeys (single-storey versus multi-storey), year of construction (built before 1945, built between 1946-1994, built between 1995-2008, built since 2009), energy classification (energy classes a and b versus minimum requirements) and compactness factors (envelope area ratio to volume and envelope area ratio to floor area). additionally, those companies (producers or building companies) with 5 or more measurements were grouped to analyse the effect of systematic measurements on them. for all buildings built since 2009 an additional grouping based on production technology was described to compare on-site building practice to prefabrication for lightweight timber construction, and hand-made building logs to prefabricated building logs for log-houses. the prefabrication level for lightweight timber construction differs between different companies. for volumetric modules the building envelope is typically finished internally and externally and air-tightness is controlled with vapour control membranes separately for each module. prefabricated separate roof and wall elements are typically structurally complete but the internal finishing layers and external cladding are completed on-site allowing for additional taping to connect the vapour control membranes between the separate elements. for both production types the vapour control layer (polyethylene sheet) is used on the interior side of the load bearing structures (figure 1). fig. 1 a typical solution for prefabricated glulam timber log structures (left) and lightweight external wall timber structure with and without additional installation layer (right) for better air tightness and moisture safety used in estonia. the air tightness layer is marked with black dashed line results as expected, the median air leakage (q50) of older buildings between 10.7 and 13.9 m 3/(hm2) has decreased to 1.1 m3/(hm2) after the minimum requirements for energy efficiency have taken effect (fig. 2). a more detailed analysis on buildings (137 in total) built since 2009 described the effect of different factors on air leakage (table 1). 39 journal of sustainable architecture and civil engineering 2019/1/24 fig. 2 air leakage rates of detached (left) and apartment buildings (right) based on year of construction. the median values with 0.16 / 0.84 quantiles are marked results as expected, the median air leakage (q50) of older buildings between 10.7 and 13.9 m3/(hm2) has decreased to 1.1 m3/(hm2) after the minimum requirements for energy efficiency have taken effect (figure 2). a more detailed analysis on buildings (137 in total) built since 2009 described the effect of different factors on air leakage (table 1). fig. 2. air leakage rates of detached (left) and apartment buildings (right) based on year of construction. the median values with 0.16 / 0.84 quantiles are marked. table 1. effect of different factors on air leakage rate and its distribution. number of buildings air leakage rate q50, m3/(hm2) median 16% percentile 84% percentile mean q50 q50,base all wooden buildings <1945 97 10.7 6.9 16.4 12.5 6.9 17.8 1946-1994 7 13.9 9.3 28.3 17.1 9.2 26.8 1995-2008 72 3.2 1.5 8.1 5.2 5.5 9.5 >2009 137 1.1 0.8 3.1 1.8 1.6 3.0 wooden buildings 2009+ 1-storey 34 1.1 0.8 3.1 1.9 1.9 3.4 multi-storey 103 1.1 0.7 3.2 1.8 1.5 3.0 energy class a 6 0.5 0.3 1.5 0.9 1.0 2.0 energy class b 10 0.7 0.4 1.4 1.0 1.1 2.1 energy class c (minimum) 121 1.2 0.8 3.3 1.9 1.7 3.2 log-building 46 2.2 1.0 3.9 2.5 1.7 3.9 lightweight timber 91 0.9 0.7 1.6 1.4 1.5 2.6 irregular measurements 35 2.8 0.9 5.5 3.1 2.4 5.1 systematic measurements (>5) 102 1.0 0.7 2.1 1.3 0.9 2.0 table 1 effect of different factors on air leakage rate and its distribution number of buildings median air leakage rate q50, m 3/(h∙m2) median 16% percentile 84% percentile mean σq50 q50,base all wooden buildings <1945 97 10.7 6.9 16.4 12.5 6.9 17.8 1946-1994 7 13.9 9.3 28.3 17.1 9.2 26.8 1995-2008 72 3.2 1.5 8.1 5.2 5.5 9.5 >2009 137 1.1 0.8 3.1 1.8 1.6 3.0 wooden buildings 2009+ 1-storey 34 1.1 0.8 3.1 1.9 1.9 3.4 multi-storey 103 1.1 0.7 3.2 1.8 1.5 3.0 energy class a 6 0.5 0.3 1.5 0.9 1.0 2.0 energy class b 10 0.7 0.4 1.4 1.0 1.1 2.1 energy class c (minimum) 121 1.2 0.8 3.3 1.9 1.7 3.2 log-building 46 2.2 1.0 3.9 2.5 1.7 3.9 lightweight timber 91 0.9 0.7 1.6 1.4 1.5 2.6 irregular measurements 35 2.8 0.9 5.5 3.1 2.4 5.1 systematic measurements (>5) 102 1.0 0.7 2.1 1.3 0.9 2.0 the energy classification a or b contributed to slightly lower median air leakage (0.5 / 0.7 m3/ (hm2)) than buildings designed to meet minimum requirements (1.2 m3/(hm2)). the lightweight timber construction (0.9 m3/(hm2)) had significantly lower air leakage compared to log houses (2.2 m3/(hm2)). this can be due to fact that the airtightness has been predominantly measured in prefabricated buildings compared to on-site building. the companies which are systematically conducting air leakage measurements (5 or more measurements in dataset) have significantly lower air leakage rates in those buildings (1.0 m3/(hm2)) compared to buildings in the irregular measurement group (2.8 m3/(hm2)). all those differences were statistically significant with p-value < 0.05. journal of sustainable architecture and civil engineering 2019/1/24 40 as can be seen from the table 1, the number of storeys did not have an effect on air leakage of the building envelope. both groups have equal air leakage (1.1 m3/(hm2)). surprisingly, the analysis showed no significant difference between buildings with different compactness factors or different number of storeys (fig. 3) although a lower air leakage rate was expected for buildings with better compactness through favourable ratio of the external envelope area to internal volume and a generally smaller number of junctions related to a more simple form factor. fig. 3 the correlation of air leakage rate (q50) and building compactness for buildings built since 2009. the envelope area to volume ratio (left) and envelope area to floor area ratio (right) are given the energy classification a or b contributed to slightly lower median air leakage (0.5 / 0.7 m3/(hm2)) than buildings designed to meet minimum requirements (1.2 m3/(hm2)). the lightweight timber construction (0.9 m3/(hm2)) had significantly lower air leakage compared to log houses (2.2 m3/(hm2)). this can be due to fact that the airtightness has been predominantly measured in prefabricated buildings compared to on-site building. the companies which are systematically conducting air leakage measurements (5 or more measurements in dataset) have significantly lower air leakage rates in those buildings (1.0 m3/(hm2)) compared to buildings in the irregular measurement group (2.8 m3/(hm2)). all those differences were statistically significant with p-value < 0.05. as can be seen from the table 1, the number of storeys did not have an effect on air leakage of the building envelope. both groups have equal air leakage (1.1 m3/(hm2)). surprisingly, the analysis showed no significant difference between buildings with different compactness factors or different number of storeys (figure 3) although a lower air leakage rate was expected for buildings with better compactness through favourable ratio of the external envelope area to internal volume and a generally smaller number of junctions related to a more simple form factor. fig. 3. the correlation of air leakage rate (q50) and building compactness for buildings built since 2009. the envelope area to volume ratio (left) and envelope area to floor area ratio (right) are given. as the construction technique had a great effect on an average air leakage, both groups (log-buildings and lightweight buildings) were further analysed to see if prefabrication has a significant effect as expected. as can be seen from table 2, the prefabricated log-buildings (1.6 m3/(hm2)) are 55% more airtight than hand-made log-buildings (3.6 m3/(hm2)). in the case of lightweight timber buildings, the prefabrication has even larger effect and prefabricated buildings (0.9 m3/(hm2)) have 74% lower air leakage rate compared to on-site building (3.4 m3/(hm2)). table 2. the effect of prefabrication on air leakage rate and its distribution for sub-construction types. number of buildings air leakage rate q50, m3/(hm2) median 16% percentile 84% percentile mean q50 q50,base all log buildings 2009+ handmade logs 13 3.6 2.7 5.8 4.2 1.9 5.9 prefabricated logs 33 1.6 0.9 3.1 1.9 1.1 2.8 as the construction technique had a great effect on an average air leakage, both groups (log-buildings and lightweight buildings) were further analysed to see if prefabrication has a significant effect as expected. as can be seen from table 2, the prefabricated log-buildings (1.6 m3/(hm2)) are 55% more airtight than hand-made log-buildings (3.6 m3/(hm2)). in the case of lightweight timber buildings, the prefabrication has even larger effect and prefabricated buildings (0.9 m3/(hm2)) have 74% lower air leakage rate compared to on-site building (3.4 m3/(hm2)). table 2 the effect of prefabrication on air leakage rate and its distribution for subconstruction types number of buildings median air leakage rate q50, m 3/(h∙m2) median 16% percentile 84% percentile mean σq50 q50,base all log buildings 2009+ handmade logs 13 3.6 2.7 5.8 4.2 1.9 5.9 prefabricated logs 33 1.6 0.9 3.1 1.9 1.1 2.8 all lightweight timber buildings 2009+ prefabricated elements 80 0.9 0.7 1.3 1.1 0.7 1.6 on-site building 11 3.4 1.4 6.0 4.0 2.7 6.7 the effect of systematic measurement practice within manufacturing or building companies were further analysed separately for log-buildings and lightweight timber construction. similarly to the full dataset, the effect of systematic measurements in both groups of different construction technologies was significant, but the differences were smaller (table 3). within log-buildings the systematic measurements showed 37% lower air leakage rates. within lightweight timber buildings the systematic measurements showed 47% lower air leakage rates. this means that systematic measurements give good feedback to manufacturers and building companies about the air leakages, with possibilities to improve the air-tightness system used and quality control system used. 41 journal of sustainable architecture and civil engineering 2019/1/24 table 3 the effect of systematic measurements on air leakage rate and its distribution for subconstruction types air leakage rate q50, m 3/(h∙m2) n median 16% percentile 84% percentile mean σq50 q50,base all log buildings 2009+ irregular measurements 11 3.0 1.9 6.3 3.9 2.3 6.1 systematic measurements (>5) 35 1.9 0.9 3.5 2.1 1.2 3.1 all lightweight timber buildings 2009+ irregular measurements 24 1.7 0.8 4.6 2.7 2.4 4.8 systematic measurements (>5) 67 0.9 0.7 1.3 1.0 0.4 1.2 for visual comparison between different building technologies within companies that conduct systematic measurements on their buildings the average (median) air leakage rates along with 16% and 84% percentiles are given in fig. 4. it can be seen from fig. 4 that log-buildings have a significantly higher variation within the same company compared to prefabricated lightweight elements. fig. 4 comparison of air leakage rates and its distribution between companies that conduct systematic measurements (a – log buildings, b – volumetric prefabricated modules, c – prefabricated wall/ roof elements) fig. 3. comparison of air leakage rates and its distribution between companies that conduct systematic measurements (a – log buildings, b – volumetric prefabricated modules, c – prefabricated wall/roof elements). the prefabricated volumetric and regular modules have a lower variation and the median values of air leakages are around q50 = 1.0 m3/(hm2) or even lower. the higher variation in measurements is significantly affecting the base values of air leakage rates for these construction technologies. for handmade log buildings the base value q50,base = 5.9 m3/(hm2). for prefabricated log buildings the base value of air leakage is 53% lower resulting in q50,base = 2.8 m3/(hm2). both construction technologies cannot compete with prefabricated modular technology, where base value of air leakage rate q50,base = 1.6 m3/(hm2). for a comparison, the base value of air leakage rate q50,base for all timber buildings built since 2009 is 3.0 m3/(hm2). discussion the results confirm that buildings built after the energy performance requirements have taken effect have significantly lower air leakage than older buildings with median q50 of 1.1 (m3/(hm2)) and range of 0.8 – 3.1 (m3/(hm2)) corresponding to 16% and 84% quantiles. this corresponds well with other countries where new buildings had similar air leakage rates. in poland, typical new building construction was characterised by airtightness n50 in the range of 1.6 to 2.6 h-1 (górzeński et.al 2016). similar results have been achieved for timber-frame low-energy houses in norway, where measured apartments had airtightness n50 in the range of 0.5 to 1.3 h-1 (relander and holøs 2018). according to the previous study of estonian building stock, the most significant factors affecting the air tightness were the quality of workmanship and supervision, as well the number of storeys of the house, both showing a more than a two-fold effect (kalamees 2007). this study shows that, for newer buildings, the prefabricated volumetric and regular modules have a lower variation and the median values of air leakages are around q50 = 1.0 m 3/(hm2) or even lower. the higher variation in measurements is significantly affecting the base values of air leakage rates for these construction technologies. for handmade log buildings the base value q50,base = 5.9 m 3/(hm2). for prefabricated log buildings the base value of air leakage is 53% lower resulting in q50,base = 2.8 m 3/(hm2). both construction technologies cannot compete with prefabricated modular technology, where base value of air leakage rate q50,base = 1.6 m 3/(hm2). for a comparison, the base value of air leakage rate q50,base for all timber buildings built since 2009 is 3.0 m3/(hm2). discussion the results confirm that buildings built after the energy performance requirements have taken effect have significantly lower air leakage than older buildings with median q50 of 1.1 (m3/(hm2)) and range of 0.8 – 3.1 (m3/(hm2)) corresponding to 16% and 84% quantiles. this corresponds well with journal of sustainable architecture and civil engineering 2019/1/24 42 other countries where new buildings had similar air leakage rates. in poland, typical new building construction was characterised by airtightness n50 in the range of 1.6 to 2.6 h -1 (górzeński et.al 2016). similar results have been achieved for timber-frame low-energy houses in norway, where measured apartments had airtightness n50 in the range of 0.5 to 1.3 h -1 (relander and holøs 2018). according to the previous study of estonian building stock, the most significant factors affecting the air tightness were the quality of workmanship and supervision, as well the number of storeys of the house, both showing a more than a two-fold effect (kalamees 2007). this study shows that, for newer buildings, the number of storeys no longer has any effect on air-tightness. this refers to the fact that a systematic approach to designing the air-tight envelope avoids large air leakages related to external wall and intermediate ceiling junctions in older buildings. furthermore, non-existent correlation between airtightness and compactness of the building envelope refers to the assumption that if systematic quality assurance with a proper air tightness concept in all junctions is used, the geometric and structural complexity of the building envelope is no longer a key factor while achieving air tightness in estonia. it has to be noted that similar studies in finland have shown significant differences in building airtightness depending on the number of storeys, with timber-frame multi-storey buildings (4.8 m3/(hm2)) having higher air-leakage rates than single-storey buildings (3.4 m3/(hm2)), referring to the fact that these kinds of effects are related to local building technologies and overall quality assurance mechanisms (vihna et.al 2015). the quality of workmanship through systematic measurements as well as prefabrication showed significant improvement in the full dataset and in both subgroups (log-buildings and lightweight timber buildings) corresponding to a 37% to 74% improvement, depending on the factor and group. the differences in other grouping factors were significantly smaller. for buildings with better air tightness target including buildings with higher designed energy efficiency and quality management similar sealing measures are utilised including systematic use of specialised membranes and sealing tapes with a significant attention to connections between openings and external wall. the results from this study give an overview of average air leakage rates along with the variation for different grouping factors related to building geometry and construction technology. assuming consistency in construction technologies and in quality assurance mechanisms, these average values with appropriate safety margins can be used for energy calculation in estonian conditions for new buildings, or buildings in respective age groups. the base values calculated and stated in tables 1, 2 and 3 take into account the variation of the measured results and try to give estimates for each grouping factor with a 75% margin and 84% confidence interval. due to the high variation in measured values, the base values are much higher than median or mean air leakage rates. the base values for buildings built since 2009 are in a range of 1.6 to 3.9 m3/(hm2) with a value of 3.0 m3/(hm2) for all buildings. the lowest base value of air leakage rate is for a group of prefabricated lightweight timber buildings with a value of q50,base = 1.6 m 3/(hm2). the groups with an energy classification target of a or b energy class, or systematic measurement practice within a single company achieved a base value q50,base around 2.0 m 3/(hm2), while on-site construction along with handmade log-buildings achieved a base value q50,base 6.7 m 3/(hm2) and 5.9 m3/(hm2) respectively. conclusions the air-tightness of estonian wooden buildings has improved by a factor of 10 since the minimum requirements for energy efficiency have taken effect. buildings with a higher energy efficiency target also have a slightly better air leakage rate. prefabrication with light-weight timber construction technology seems to be superior to traditional log-wood building and notably, prefabrication improves air-tightness even within log-wood building or lightweight building groups, meaning that on-site building or the use of handmade logs corresponds to significantly higher air leakages. the compactness factor and number of storeys did not have a significant effect on air leakage referring to the fact that if systematic quality assurance with a proper air tightness concept is used, the geometric and structural complexity of the building envelope is no longer a key factor while achieving air tightness. 43 journal of sustainable architecture and civil engineering 2019/1/24 this research was supported by the estonian research council with personal research funding prg483 “moisture safety of interior insulation, constructional moisture and thermally efficient building envelope”, institutional research funding grant iut1-15, estonian centre of excellence in zero energy and resource efficient smart buildings and districts, zebe, grant tk146 funded by the european regional development fund and h2020 project no 754177: “nero cost reduction of new nearly zero-energy wooden buildings in the northern climatic conditions”. acknowledgment colijn m., entrop a.g., toxopeus m.e. evaluating the effectiveness of improved workmanship quality on the airtightness of dutch detached houses. energy procedia, 2017; 132: 843-848. https://doi. org/10.1016/j.egypro.2017.09.670 górzeński r., szymański m., górka a., mróz t. airtightness of buildings in poland. international journal of ventilation, 2014; 12: 391-400. https://doi.org /10.1080/14733315.2014.11684032 relander t.o., holøs s. airtightness measurements of wood frame low energy row houses. building enclosure science & technology (best2) conference proceedings, 2018. kalamees t. air tightness and air leakages of new lightweight single-family detached houses in estonia. building and environment, 2007; 42: 2369–2377. https://doi.org/10.1016/j.buildenv.2006.06.001 mortensen l.h., bergsøe n.c. air tightness measurements in older danish single-family houses. energy procedia, 2017; 132: 825–830. https://doi. org/10.1016/j.egypro.2017.10.016 rt 80-10974 teollisesti valmistettujen asuinrakennusten ilmanpitävyyden laadunvarmistusohje [airtightness management manual for prefabricated residential buildings], rakennustieto oy. 2009. relander t.o, holøs s., thue j.v. airtightness estimation—a state of the art review and an en route upper limit evaluation principle to increase the chances that wood-frame houses with a vapour and wind-barrier comply with the airtightness requirements. energy and buildings, 2012; 54: 444– 452. https://doi.org/10.1016/j.enbuild.2012.07.012 vinha j., manelius e., korpi m., salminen k., kurnitski j., kiviste m., laukkarinen a. airtightness of residential buildings in finland. building and environment, 2015; 93: 128-140. https://doi.org/10.1016/j. buildenv.2015.06.011 jaanus hallik phd canditate tallinn university of technology, department of civil engineering and architecture, nearly zero energy buildings research group main research area minimising of heat loss of nzeb building envelope address ehitajate tee 5, tallinn 19086, estonia tel. +372 5021841 e-mail: jaanus.hallik@taltech.ee targo kalamees professor tallinn university of technology, department of civil engineering and architecture, nearly zero energy buildings research group main research area building envelope structures; renovation of buildings; hygrothermal behaviour of buildings structures (computer simulations, laboratory experiments, field studies); moisture safety of buildings; boundary conditions for hygrothermal simulations and experiments; building energy consumption and healthy building design; indoor climate and indoor air quality of residential-, office-, and historic buildings address ehitajate tee 5, tallinn 19086, estonia tel. +3726202403 e-mail: targo.kalamees@taltech.ee references about the authors journal of sustainable architecture and civil engineering 2018/1/22 76 *corresponding author: aturphd@gmail.com reliability approaches to modeling of the nonlinear pseudo-static response of rc-structural systems in accidental design situations received 2018/02/18 accepted after revision 2018/06/06 journal of sustainable architecture and civil engineering vol. 1 / no. 22 / 2018 pp. 76-87 doi 10.5755/j01.sace.22.1.20194 © kaunas university of technology reliability approaches to modeling of the nonlinear pseudostatic response of rc-structural systems in accidental design situations jsace 1/22 http://dx.doi.org/10.5755/j01.sace.22.1.20194 andrei tur*, viktar tur brest state technical university, faculty of civil engineering, moskovskaya 267, 224017, brest, republic of belarus introduction the nonlinear structural analysis is considered as a basic design procedure, which is used for checking of the structural robustness in accidental design situation. it is explained by following reason: a nonlinear structural analysis based on realistic constitutive relations for basic variables (average values) makes possible a simulation of a real structural behavior. it should be pointed that, implementation of the nonlinear structural analysis in design of concrete structures requires an alternate approach to safety verification. the paper presents a new approach to safety format for nonlinear analysis of rc structures subjected to accidental loads. keywords: nonlinear analysis, progressive collapse, safety format, robustness, reliability. in recent years structural engineers try to use nonlinear analysis while designing a new complex structural system as well as for checking of the existing structures. nonlinear analysis (static and dynamic) is most widely used as a main computational tool for checking of robustness of the structural systems in accidental design situations (accidental limit states checking). as it was stated in červenka (2013a), “evaluations of the nonlinear analysis are supported by rapid increase of computational power as well as new capabilities of the available tools for numerical simulations of structural performance”. the first published works dealing with nonlinear finite element analysis of concrete systems emerged in the late 1960. these studies focused on various aspects of element formations, including crack propagation and the bonding of reinforcement. in general case two basic femmethods are used for non-linear modeling: 1) so-called stiffness method (modified stiffness model); 2) layered model. the stiffness adaptation analysis is purposed to be an alternative for a full nonlinear analysis (layered model) for calculating load distributions, deformations, crack patterns and crack-width in reinforced concrete structures. in stiffness adaptation analysis both standards linear elastic material as well as non-linear material behavior can be defined (hu and schnobrich 1991). nonlinear materials can be defined through 77 journal of sustainable architecture and civil engineering 2018/1/22 a uni-axial stress-strain curve, both in the tensile and in the compressive state. nonlinear stressstrain curves may also be defined for bar and grid reinforcement. in case of the layered model approach each concrete layer is assumed to be in a state of plane stress and the actual stress distribution of the concrete section is modeled by a piecewise constant approximation. in general case, for the reinforcement concrete section, the final form of the stress resultant constitutive matrix at an integration point can be written as: reliability approaches to modeling of the nonlinear pseudo-static response of rc-structural systems in accidental design situations andrei tur*, viktar tur brest state technical university, faculty of civil engineering, moskovskaya 267, 224017, brest, republic of belarus *corresponding author: aturphd@gmail.com the nonlinear structural analysis is considered as a basic design procedure, which is used for checking of the structural robustness in accidental design situation. it is explained by following reason: a nonlinear structural analysis based on realistic constitutive relations for basic variables (average values) makes possible a simulation of a real structural behavior. it should be pointed that, implementation of the nonlinear structural analysis in design of concrete structures requires an alternate approach to safety verification. the paper presents a new approach to safety format for nonlinear analysis of rc structures subjected to accidental loads. keywords: nonlinear analysis, progressive collapse, safety format, robustness, reliability. 1. introduction. in recent years structural engineers try to use nonlinear analysis while designing a new complex structural system as well as for checking of the existing structures. nonlinear analysis (static and dynamic) is most widely used as a main computational tool for checking of robustness of the structural systems in accidental design situations (accidental limit states checking). as it was stated in červenka (2013a), “evaluations of the nonlinear analysis are supported by rapid increase of computational power as well as new capabilities of the available tools for numerical simulations of structural performance”. the first published works dealing with nonlinear finite element analysis of concrete systems emerged in the late 1960. these studies focused on various aspects of element formations, including crack propagation and the bonding of reinforcement. in general case two basic fem-methods are used for non-linear modeling: 1) so-called stiffness method (modified stiffness model); 2) layered model. the stiffness adaptation analysis is purposed to be an alternative for a full nonlinear analysis (layered model) for calculating load distributions, deformations, crack patterns and crack-width in reinforced concrete structures. in stiffness adaptation analysis both standards linear elastic material as well as non-linear material behavior can be defined (hu and schnobrich 1991). nonlinear materials can be defined through a uni-axial stress-strain curve, both in the tensile and in the compressive state. nonlinear stress-strain curves may also be defined for bar and grid reinforcement. in case of the layered model approach each concrete layer is assumed to be in a state of plane stress and the actual stress distribution of the concrete section is modeled by a piecewise constant approximation. in general case, for the reinforcement concrete section, the final form of the stress resultant constitutive matrix at an integration point can be written as:               0 t t rd t t rd t t t rd n v d m                           , (1) where:  d  is the stiffness matrix that can be established by assembling the contributions of all the concrete layers, all steel layers and transverse shear stiffness. as it was shown above, nonlinear analysis take into account the nonlinear deformation properties of rcsections, based on physical constitutive relations (“ σ ε ” for material properties) and makes possible a simulation of a real structural behavior. if reflects an integral response, where all local sections interact and therefore it requires an adequate approach for safety verification (note, that in partial safety factor (psf) method (en 1990: 2006) we assume a failure probabilities of separate materials, but do not evaluate the failure probability on the structural level). it should be underlined, that nonlinear analysis offers a verification of global resistance and requires a safety format for global resistance (červenka 2013b). in accordance with červenka (2013b), the term global resistance (global safety) is used for “assessment of structural response on higher structural level than a cross-section”. the term global resistance is introduced in červenka (2013b) in order to distinguish the newly introduced check of safety on global level, as compared to local safety check in the partial safety factor method (psf-method) in accordance with en 1990 (2006). (1) where: [ ]d – is the stiffness matrix that can be established by assembling the contributions of all the concrete layers, all steel layers and transverse shear stiffness. as it was shown above, nonlinear analysis take into account the nonlinear deformation properties of rc-sections, based on physical constitutive relations (“ ó å− ” for material properties) and makes possible a simulation of a real structural behavior. if reflects an integral response, where all local sections interact and therefore it requires an adequate approach for safety verification (note, that in partial safety factor (psf) method (en 1990: 2006) we assume a failure probabilities of separate materials, but do not evaluate the failure probability on the structural level). it should be underlined, that nonlinear analysis offers a verification of global resistance and requires a safety format for global resistance (červenka 2013b). in accordance with červenka (2013b), the term global resistance (global safety) is used for “assessment of structural response on higher structural level than a cross-section”. the term global resistance is introduced in červenka (2013b) in order to distinguish the newly introduced check of safety on global level, as compared to local safety check in the partial safety factor method (psf-method) in accordance with en 1990 (2006). he historical review (from cem mc78 to fib mc2010) of the non-linear safety format development was described in detail in sangiorgio (2015). with the implementation of the new fib mc2010 (2010), a different perspective was placed on nonlinear analysis and safety assessment. the design condition to be used in safety format for nonlinear analysis is written in the external actions and resisting internal forces domain: 2. safety format for nonlinear analysis in accordance with actual codes provision. the historical review (from cem mc78 to fib mc2010) of the non-linear safety format development was described in detail in sangiorgio (2015). with the implementation of the new fib mc2010 (2010), a different perspective was placed on nonlinear analysis and safety assessment. the design condition to be used in safety format for nonlinear analysis is written in the external actions and resisting internal forces domain: d de r , (2) where: de  is the design value of the action; dr  is the design value of resistance. three different approaches are proposed to evaluate the design resistance dr (depending on various levels of implementations of probabilistic theory): (1) full probabilistic method, recommended by jcss as a basic method; (2) the global resistance method; and (3) the partial factor method (psf-method). in the global resistance format, the resistance is considered on a global structural level. two alternative methods are mentioned in fib mc2010 (2010) for the derivation of the design resistance dr : (1) global resistance factor method (which was adopted from en 1992-2 (2005), slightly modified); and (2) ecov-method, proposed by červenka (2013b) and sykora and holicky (2011) (estimations of coefficient variation for resistance). in this case, the safety margin can be expressed by the global safety factor as: md r r r   , (3) where: mr  is the mean resistance. the global safety factor r cover all uncertainties and can be related to the coefficient of variations of resistance rv (according a lndistribution (!) according en 1992-2 (2005)) as exp( )r r rv    . a simplified formulation was proposed in fib mc2010 (2010), where in denominator of the right hand side in eq. (3) is product of two factors r m rd    (sykora and holicky 2011). the first factor m is related to material uncertainty and can be established by probabilistic analysis. the second factor rd is related to model and geometrical uncertainties and recommended value are in range 1.05…1.1 only (!) (as suggested by en 1992-2 (2005)). as it was stated in sangiorgio (2015), after the new fib mc 2010 (2010), although the topic is still controversial, only few contributions were found in literature (schlune et al. 2011, allaix et al. 2013). the first contribution was presented by schlune et al. (2011). design resistance dr is then derived by division of the obtained mean resistance mr by global resistance factor r : ( , , )ym cm nom d r r f f a r   , (4) where: exp( )r r r m v      again based on the assumption of a lognormal distributed resistance. model uncertainties are explicitly taken into accounts thought the use of the bias factor θm , which is defined as the mean ratio of experimental to predicted resistance (in accordance with schlune et al. (2011)) its value varies between 0.7 and 1.2 for failure in compression, bending and shear). the coefficient variation of structural resistance rv is written as follows: 2 2 2r g m fv v v v   , (5) where: , ,g m fv v v  are the coefficients of variations of the geometrical, model and material uncertainties respectively, estimated in accordance with schlune et al. (2011). according with the second contributions, proposed by (allaix and mancini 2007, allaix et al. 2013) the design resistance dr is derived by divisions of obtained resistance factor r and the model uncertainty factor rd : ( , , )ym cm nom d r rd r f f a r    , (6) in this case, the global resistance factor r is derived from coefficient of variations of the structural resistance rv (estimated by probabilistic method or based on červenka method ecov): exp( )r r rv    , (7) where:  is the reliability index in accordance with en 1990; r is the sensitivity factor for resistance. (2) where: de – is the design value of the action; dr – is the design value of resistance. three different approaches are proposed to evaluate the design resistance dr (depending on various levels of implementations of probabilistic theory): (1) full probabilistic method, recommended by jcss as a basic method; (2) the global resistance method; and (3) the partial factor method (psf-method). in the global resistance format, the resistance is considered on a global structural level. two alternative methods are mentioned in fib mc2010 (2010) for the derivation of the design resistance dr : (1) global resistance factor method (which was adopted from en 1992-2 (2005), slightly modified); and (2) ecov-method, proposed by červenka (2013b) and sykora and holicky (2011) (estimations of coefficient variation for resistance). in this case, the safety margin can be expressed by the global safety factor as: 2. safety format for nonlinear analysis in accordance with actual codes provision. the historical review (from cem mc78 to fib mc2010) of the non-linear safety format development was described in detail in sangiorgio (2015). with the implementation of the new fib mc2010 (2010), a different perspective was placed on nonlinear analysis and safety assessment. the design condition to be used in safety format for nonlinear analysis is written in the external actions and resisting internal forces domain: d de r , (2) where: de  is the design value of the action; dr  is the design value of resistance. three different approaches are proposed to evaluate the design resistance dr (depending on various levels of implementations of probabilistic theory): (1) full probabilistic method, recommended by jcss as a basic method; (2) the global resistance method; and (3) the partial factor method (psf-method). in the global resistance format, the resistance is considered on a global structural level. two alternative methods are mentioned in fib mc2010 (2010) for the derivation of the design resistance dr : (1) global resistance factor method (which was adopted from en 1992-2 (2005), slightly modified); and (2) ecov-method, proposed by červenka (2013b) and sykora and holicky (2011) (estimations of coefficient variation for resistance). in this case, the safety margin can be expressed by the global safety factor as: md r r r   , (3) where: mr  is the mean resistance. the global safety factor r cover all uncertainties and can be related to the coefficient of variations of resistance rv (according a lndistribution (!) according en 1992-2 (2005)) as exp( )r r rv    . a simplified formulation was proposed in fib mc2010 (2010), where in denominator of the right hand side in eq. (3) is product of two factors r m rd    (sykora and holicky 2011). the first factor m is related to material uncertainty and can be established by probabilistic analysis. the second factor rd is related to model and geometrical uncertainties and recommended value are in range 1.05…1.1 only (!) (as suggested by en 1992-2 (2005)). as it was stated in sangiorgio (2015), after the new fib mc 2010 (2010), although the topic is still controversial, only few contributions were found in literature (schlune et al. 2011, allaix et al. 2013). the first contribution was presented by schlune et al. (2011). design resistance dr is then derived by division of the obtained mean resistance mr by global resistance factor r : ( , , )ym cm nom d r r f f a r   , (4) where: exp( )r r r m v      again based on the assumption of a lognormal distributed resistance. model uncertainties are explicitly taken into accounts thought the use of the bias factor θm , which is defined as the mean ratio of experimental to predicted resistance (in accordance with schlune et al. (2011)) its value varies between 0.7 and 1.2 for failure in compression, bending and shear). the coefficient variation of structural resistance rv is written as follows: 2 2 2r g m fv v v v   , (5) where: , ,g m fv v v  are the coefficients of variations of the geometrical, model and material uncertainties respectively, estimated in accordance with schlune et al. (2011). according with the second contributions, proposed by (allaix and mancini 2007, allaix et al. 2013) the design resistance dr is derived by divisions of obtained resistance factor r and the model uncertainty factor rd : ( , , )ym cm nom d r rd r f f a r    , (6) in this case, the global resistance factor r is derived from coefficient of variations of the structural resistance rv (estimated by probabilistic method or based on červenka method ecov): exp( )r r rv    , (7) where:  is the reliability index in accordance with en 1990; r is the sensitivity factor for resistance. (3) where: mr – is the mean resistance. the global safety factor rγ cover all uncertainties and can be related to the coefficient of variations safety format for nonlinear analysis in accordance with actual codes provision journal of sustainable architecture and civil engineering 2018/1/22 78 of resistance rv (according a lndistribution (!) according en 1992-2 (2005)) as exp( )r r rvγ = α β . a simplified formulation was proposed in fib mc2010 (2010), where in denominator of the right hand side in eq. (3) is product of two factors r m rdγ = γ ⋅γ (sykora and holicky 2011). the first factor mγ is related to material uncertainty and can be established by probabilistic analysis. the second factor rdγ is related to model and geometrical uncertainties and recommended value are in range 1.05…1.1 only (!) (as suggested by en 1992-2(2005)). as it was stated in sangiorgio (2015), after the new fib mc 2010 (2010), although the topic is still controversial, only few contributions were found in literature (schlune et al. 2011, allaix et al. 2013). the first contribution was presented by schlune et al. (2011). design resistance dr is then derived by division of the obtained mean resistance mr by global resistance factor rγ : 2. safety format for nonlinear analysis in accordance with actual codes provision. the historical review (from cem mc78 to fib mc2010) of the non-linear safety format development was described in detail in sangiorgio (2015). with the implementation of the new fib mc2010 (2010), a different perspective was placed on nonlinear analysis and safety assessment. the design condition to be used in safety format for nonlinear analysis is written in the external actions and resisting internal forces domain: d de r , (2) where: de  is the design value of the action; dr  is the design value of resistance. three different approaches are proposed to evaluate the design resistance dr (depending on various levels of implementations of probabilistic theory): (1) full probabilistic method, recommended by jcss as a basic method; (2) the global resistance method; and (3) the partial factor method (psf-method). in the global resistance format, the resistance is considered on a global structural level. two alternative methods are mentioned in fib mc2010 (2010) for the derivation of the design resistance dr : (1) global resistance factor method (which was adopted from en 1992-2 (2005), slightly modified); and (2) ecov-method, proposed by červenka (2013b) and sykora and holicky (2011) (estimations of coefficient variation for resistance). in this case, the safety margin can be expressed by the global safety factor as: md r r r   , (3) where: mr  is the mean resistance. the global safety factor r cover all uncertainties and can be related to the coefficient of variations of resistance rv (according a lndistribution (!) according en 1992-2 (2005)) as exp( )r r rv    . a simplified formulation was proposed in fib mc2010 (2010), where in denominator of the right hand side in eq. (3) is product of two factors r m rd    (sykora and holicky 2011). the first factor m is related to material uncertainty and can be established by probabilistic analysis. the second factor rd is related to model and geometrical uncertainties and recommended value are in range 1.05…1.1 only (!) (as suggested by en 1992-2 (2005)). as it was stated in sangiorgio (2015), after the new fib mc 2010 (2010), although the topic is still controversial, only few contributions were found in literature (schlune et al. 2011, allaix et al. 2013). the first contribution was presented by schlune et al. (2011). design resistance dr is then derived by division of the obtained mean resistance mr by global resistance factor r : ( , , )ym cm nom d r r f f a r   , (4) where: exp( )r r r m v      again based on the assumption of a lognormal distributed resistance. model uncertainties are explicitly taken into accounts thought the use of the bias factor θm , which is defined as the mean ratio of experimental to predicted resistance (in accordance with schlune et al. (2011)) its value varies between 0.7 and 1.2 for failure in compression, bending and shear). the coefficient variation of structural resistance rv is written as follows: 2 2 2r g m fv v v v   , (5) where: , ,g m fv v v  are the coefficients of variations of the geometrical, model and material uncertainties respectively, estimated in accordance with schlune et al. (2011). according with the second contributions, proposed by (allaix and mancini 2007, allaix et al. 2013) the design resistance dr is derived by divisions of obtained resistance factor r and the model uncertainty factor rd : ( , , )ym cm nom d r rd r f f a r    , (6) in this case, the global resistance factor r is derived from coefficient of variations of the structural resistance rv (estimated by probabilistic method or based on červenka method ecov): exp( )r r rv    , (7) where:  is the reliability index in accordance with en 1990; r is the sensitivity factor for resistance. (4) where: exp( )r r r m vα β γ = θ – again based on the assumption of a lognormal distributed resistance. model uncertainties are explicitly taken into accounts thought the use of the bias factor è m , which is defined as the mean ratio of experimental to predicted resistance (in accordance with schlune et al. (2011)) its value varies between 0.7 and 1.2 for failure in compression, bending and shear). the coefficient variation of structural resistance rv is written as follows: 2. safety format for nonlinear analysis in accordance with actual codes provision. the historical review (from cem mc78 to fib mc2010) of the non-linear safety format development was described in detail in sangiorgio (2015). with the implementation of the new fib mc2010 (2010), a different perspective was placed on nonlinear analysis and safety assessment. the design condition to be used in safety format for nonlinear analysis is written in the external actions and resisting internal forces domain: d de r , (2) where: de  is the design value of the action; dr  is the design value of resistance. three different approaches are proposed to evaluate the design resistance dr (depending on various levels of implementations of probabilistic theory): (1) full probabilistic method, recommended by jcss as a basic method; (2) the global resistance method; and (3) the partial factor method (psf-method). in the global resistance format, the resistance is considered on a global structural level. two alternative methods are mentioned in fib mc2010 (2010) for the derivation of the design resistance dr : (1) global resistance factor method (which was adopted from en 1992-2 (2005), slightly modified); and (2) ecov-method, proposed by červenka (2013b) and sykora and holicky (2011) (estimations of coefficient variation for resistance). in this case, the safety margin can be expressed by the global safety factor as: md r r r   , (3) where: mr  is the mean resistance. the global safety factor r cover all uncertainties and can be related to the coefficient of variations of resistance rv (according a lndistribution (!) according en 1992-2 (2005)) as exp( )r r rv    . a simplified formulation was proposed in fib mc2010 (2010), where in denominator of the right hand side in eq. (3) is product of two factors r m rd    (sykora and holicky 2011). the first factor m is related to material uncertainty and can be established by probabilistic analysis. the second factor rd is related to model and geometrical uncertainties and recommended value are in range 1.05…1.1 only (!) (as suggested by en 1992-2 (2005)). as it was stated in sangiorgio (2015), after the new fib mc 2010 (2010), although the topic is still controversial, only few contributions were found in literature (schlune et al. 2011, allaix et al. 2013). the first contribution was presented by schlune et al. (2011). design resistance dr is then derived by division of the obtained mean resistance mr by global resistance factor r : ( , , )ym cm nom d r r f f a r   , (4) where: exp( )r r r m v      again based on the assumption of a lognormal distributed resistance. model uncertainties are explicitly taken into accounts thought the use of the bias factor θm , which is defined as the mean ratio of experimental to predicted resistance (in accordance with schlune et al. (2011)) its value varies between 0.7 and 1.2 for failure in compression, bending and shear). the coefficient variation of structural resistance rv is written as follows: 2 2 2r g m fv v v v   , (5) where: , ,g m fv v v  are the coefficients of variations of the geometrical, model and material uncertainties respectively, estimated in accordance with schlune et al. (2011). according with the second contributions, proposed by (allaix and mancini 2007, allaix et al. 2013) the design resistance dr is derived by divisions of obtained resistance factor r and the model uncertainty factor rd : ( , , )ym cm nom d r rd r f f a r    , (6) in this case, the global resistance factor r is derived from coefficient of variations of the structural resistance rv (estimated by probabilistic method or based on červenka method ecov): exp( )r r rv    , (7) where:  is the reliability index in accordance with en 1990; r is the sensitivity factor for resistance. (5) where: , ,g m fv v v – are the coefficients of variations of the geometrical, model and material uncertainties respectively, estimated in accordance with schlune et al. (2011). according with the second contributions, proposed by (allaix and mancini 2007, allaix et al. 2013) the design resistance dr is derived by divisions of obtained resistance factor rγ and the model uncertainty factor rdγ : 2. safety format for nonlinear analysis in accordance with actual codes provision. the historical review (from cem mc78 to fib mc2010) of the non-linear safety format development was described in detail in sangiorgio (2015). with the implementation of the new fib mc2010 (2010), a different perspective was placed on nonlinear analysis and safety assessment. the design condition to be used in safety format for nonlinear analysis is written in the external actions and resisting internal forces domain: d de r , (2) where: de  is the design value of the action; dr  is the design value of resistance. three different approaches are proposed to evaluate the design resistance dr (depending on various levels of implementations of probabilistic theory): (1) full probabilistic method, recommended by jcss as a basic method; (2) the global resistance method; and (3) the partial factor method (psf-method). in the global resistance format, the resistance is considered on a global structural level. two alternative methods are mentioned in fib mc2010 (2010) for the derivation of the design resistance dr : (1) global resistance factor method (which was adopted from en 1992-2 (2005), slightly modified); and (2) ecov-method, proposed by červenka (2013b) and sykora and holicky (2011) (estimations of coefficient variation for resistance). in this case, the safety margin can be expressed by the global safety factor as: md r r r   , (3) where: mr  is the mean resistance. the global safety factor r cover all uncertainties and can be related to the coefficient of variations of resistance rv (according a lndistribution (!) according en 1992-2 (2005)) as exp( )r r rv    . a simplified formulation was proposed in fib mc2010 (2010), where in denominator of the right hand side in eq. (3) is product of two factors r m rd    (sykora and holicky 2011). the first factor m is related to material uncertainty and can be established by probabilistic analysis. the second factor rd is related to model and geometrical uncertainties and recommended value are in range 1.05…1.1 only (!) (as suggested by en 1992-2 (2005)). as it was stated in sangiorgio (2015), after the new fib mc 2010 (2010), although the topic is still controversial, only few contributions were found in literature (schlune et al. 2011, allaix et al. 2013). the first contribution was presented by schlune et al. (2011). design resistance dr is then derived by division of the obtained mean resistance mr by global resistance factor r : ( , , )ym cm nom d r r f f a r   , (4) where: exp( )r r r m v      again based on the assumption of a lognormal distributed resistance. model uncertainties are explicitly taken into accounts thought the use of the bias factor θm , which is defined as the mean ratio of experimental to predicted resistance (in accordance with schlune et al. (2011)) its value varies between 0.7 and 1.2 for failure in compression, bending and shear). the coefficient variation of structural resistance rv is written as follows: 2 2 2r g m fv v v v   , (5) where: , ,g m fv v v  are the coefficients of variations of the geometrical, model and material uncertainties respectively, estimated in accordance with schlune et al. (2011). according with the second contributions, proposed by (allaix and mancini 2007, allaix et al. 2013) the design resistance dr is derived by divisions of obtained resistance factor r and the model uncertainty factor rd : ( , , )ym cm nom d r rd r f f a r    , (6) in this case, the global resistance factor r is derived from coefficient of variations of the structural resistance rv (estimated by probabilistic method or based on červenka method ecov): exp( )r r rv    , (7) where:  is the reliability index in accordance with en 1990; r is the sensitivity factor for resistance. (6) in this case, the global resistance factor rγ is derived from coefficient of variations of the structural resistance rv (estimated by probabilistic method or based on červenka method ecov): 2. safety format for nonlinear analysis in accordance with actual codes provision. the historical review (from cem mc78 to fib mc2010) of the non-linear safety format development was described in detail in sangiorgio (2015). with the implementation of the new fib mc2010 (2010), a different perspective was placed on nonlinear analysis and safety assessment. the design condition to be used in safety format for nonlinear analysis is written in the external actions and resisting internal forces domain: d de r , (2) where: de  is the design value of the action; dr  is the design value of resistance. three different approaches are proposed to evaluate the design resistance dr (depending on various levels of implementations of probabilistic theory): (1) full probabilistic method, recommended by jcss as a basic method; (2) the global resistance method; and (3) the partial factor method (psf-method). in the global resistance format, the resistance is considered on a global structural level. two alternative methods are mentioned in fib mc2010 (2010) for the derivation of the design resistance dr : (1) global resistance factor method (which was adopted from en 1992-2 (2005), slightly modified); and (2) ecov-method, proposed by červenka (2013b) and sykora and holicky (2011) (estimations of coefficient variation for resistance). in this case, the safety margin can be expressed by the global safety factor as: md r r r   , (3) where: mr  is the mean resistance. the global safety factor r cover all uncertainties and can be related to the coefficient of variations of resistance rv (according a lndistribution (!) according en 1992-2 (2005)) as exp( )r r rv    . a simplified formulation was proposed in fib mc2010 (2010), where in denominator of the right hand side in eq. (3) is product of two factors r m rd    (sykora and holicky 2011). the first factor m is related to material uncertainty and can be established by probabilistic analysis. the second factor rd is related to model and geometrical uncertainties and recommended value are in range 1.05…1.1 only (!) (as suggested by en 1992-2 (2005)). as it was stated in sangiorgio (2015), after the new fib mc 2010 (2010), although the topic is still controversial, only few contributions were found in literature (schlune et al. 2011, allaix et al. 2013). the first contribution was presented by schlune et al. (2011). design resistance dr is then derived by division of the obtained mean resistance mr by global resistance factor r : ( , , )ym cm nom d r r f f a r   , (4) where: exp( )r r r m v      again based on the assumption of a lognormal distributed resistance. model uncertainties are explicitly taken into accounts thought the use of the bias factor θm , which is defined as the mean ratio of experimental to predicted resistance (in accordance with schlune et al. (2011)) its value varies between 0.7 and 1.2 for failure in compression, bending and shear). the coefficient variation of structural resistance rv is written as follows: 2 2 2r g m fv v v v   , (5) where: , ,g m fv v v  are the coefficients of variations of the geometrical, model and material uncertainties respectively, estimated in accordance with schlune et al. (2011). according with the second contributions, proposed by (allaix and mancini 2007, allaix et al. 2013) the design resistance dr is derived by divisions of obtained resistance factor r and the model uncertainty factor rd : ( , , )ym cm nom d r rd r f f a r    , (6) in this case, the global resistance factor r is derived from coefficient of variations of the structural resistance rv (estimated by probabilistic method or based on červenka method ecov): exp( )r r rv    , (7) where:  is the reliability index in accordance with en 1990; r is the sensitivity factor for resistance. (7) where: β is the reliability index in accordance with en 1990; rα – is the sensitivity factor for resistance. the model uncertainty factor rdγ takes into account the difference between the real behavior of the structure and the results obtained based on a numerical model. the model uncertainty factor rdγ can be derived using the following expression from schlune et al. (2011): the model uncertainty factor rd takes into account the difference between the real behavior of the structure and the results obtained based on a numerical model. the model uncertainty factor rd can be derived using the following expression from schlune et al. (2011): exp( )rd r rv    , (8) where: 0, 4r r    is the sensitivity factor for resistance model uncertainty ( r <1 in order to account for separate safety assessment of resistance); rv  is the coefficient of variations of the resistance model uncertainly. the value of this coefficient of variations can be obtained based on experimental results according to en 1990 (2006). for checking of the rc-structural system in accidental design situation, two main issues must be solved: (1) to calculate the pseudo-static response of the modified structural system under accidental loads; (2) to determined target value of the reliability index for accidental design (required level of reliability). 3. pseudo-static response of the structural system with a removed vertical load bearing elements. as was stated in ellingwood (2002) prevent and mitigation of progressive collapse can be achieved using two different methods: (1) tf-method (indirect tie-force method); (2) ap – method (direct alternate load path method). the indirect (tf method) consists of improving the structural integrity of building by providing redundancy of load path and ductile detailing. currently, the en 1991-1-7, allows the use of indirect method and some guidance is contained in the en 1992-1-1. in this case criteria are devised to check the local resistance to withstand a specific postulated accidental load. the direct method, referred to as “alternate load path” (ap method), is most widely used in the practical design and based on criteria for evaluating the capability of a damaged structure to bridge over or around the damaged volume of area without progressive collapse developing from the local damage. the ap-method consists in considering internal force (effect of the actions) redistributions throughout the structure following the loss of a vertical support element (ufc 4-023-03: 2010). as was shown in ufc 4-023-03 (2010), an ap-method analysis may be performed using of the following basic nonlinear procedures: nonlinear dynamic (nld) and nonlinear static (nls) procedures. in case of the nonlinear static procedure after materially-and-geometrically nonlinear model is built, the accidental load combination are magnified by a dynamic increase factor (dif) that accounts for inertia effects and the resulting load is applied to model with removed vertical load bearing elements. if a dynamic increase factor (dif) is known, for deformationcontrolled actions, the resulting deformations are compared to the expected deformation capacities; for the force controlled action, the member strength is not modified and shell not be less than the maximum internal member forces (demands). otherwise, calculation procedure based on the energetic approach should be used. the basic provisions of this procedure are described in detail in tur (2012). the purpose here is to analyze the structural response of rc-structural systems subjected to a sudden column loss. the procedure, which is used for obtaining of the pseudo-static nonlinear response of the structural system, consists of the following main steps: (1) calculate the static non-linear response “ f δ ” for the modified structural system with a removed vertical load bearing element according to certain rules (tur 2012, vlassis 2009) (see fig. 1, line 1); (2) calculate the pseudo-static response, that taking into account inertia effects, caused by suddenly applied gravity load. in general case, based on energetic consideration (see fig. 1): , 0 ( ) u ps u up d f      , (9) (8) where: 0, 4r rα = α – is the sensitivity factor for resistance model uncertainty ( rα <1 in order to account for separate safety assessment of resistance); rvϑ – is the coefficient of variations of the resistance model uncertainly. the value of this coefficient of variations can be obtained based on experimental results according to en 1990 (2006). 79 journal of sustainable architecture and civil engineering 2018/1/22 for checking of the rc-structural system in accidental design situation, two main issues must be solved: (1) to calculate the pseudo-static response of the modified structural system under accidental loads; (2) to determined target value of the reliability index for accidental design (required level of reliability). as was stated in ellingwood (2002) prevent and mitigation of progressive collapse can be achieved using two different methods: (1) tf-method (indirect tie-force method); (2) ap – method (direct alternate load path method). the indirect (tf method) consists of improving the structural integrity of building by providing redundancy of load path and ductile detailing. currently, the en 1991-1-7, allows the use of indirect method and some guidance is contained in the en 1992-1-1. in this case criteria are devised to check the local resistance to withstand a specific postulated accidental load. the direct method, referred to as “alternate load path” (ap method), is most widely used in the practical design and based on criteria for evaluating the capability of a damaged structure to bridge over or around the damaged volume of area without progressive collapse developing from the local damage. the ap-method consists in considering internal force (effect of the actions) redistributions throughout the structure following the loss of a vertical support element (ufc 4-023-03: 2010). as was shown in ufc 4-023-03 (2010), an ap-method analysis may be performed using of the following basic nonlinear procedures: nonlinear dynamic (nld) and nonlinear static (nls) procedures. in case of the nonlinear static procedure after materially-and-geometrically nonlinear model is built, the accidental load combination are magnified by a dynamic increase factor (dif) that accounts for inertia effects and the resulting load is applied to model with removed vertical load bearing elements. if a dynamic increase factor (dif) is known, for deformation-controlled actions, the resulting deformations are compared to the expected deformation capacities; for the force controlled action, the member strength is not modified and shell not be less than the maximum internal member forces (demands). otherwise, calculation procedure based on the energetic approach should be used. the basic provisions of this procedure are described in detail in tur (2012). the purpose here is to analyze the structural response of rc-structural systems subjected to a sudden column loss. the procedure, which is used for obtaining of the pseudo-static nonlinear response of the structural system, consists of the following main steps: (1) calculate the static non-linear response “f–δ” for the modified structural system with a removed vertical load bearing element according to certain rules (tur 2012, vlassis 2009) (see fig. 1, line 1); (2) calculate the pseudo-static repseudostatic response of the structural system with a removed vertical load bearing elements fig. 1 to assessment of the pseudo-static response of the structural system in accordance with (tur 2012, vlassis 2009) journal of sustainable architecture and civil engineering 2018/1/22 80 sponse, that taking into account inertia effects, caused by suddenly applied gravity load. in general case, based on energetic consideration (see fig. 1): the model uncertainty factor rd takes into account the difference between the real behavior of the structure and the results obtained based on a numerical model. the model uncertainty factor rd can be derived using the following expression from schlune et al. (2011): exp( )rd r rv    , (8) where: 0, 4r r    is the sensitivity factor for resistance model uncertainty ( r <1 in order to account for separate safety assessment of resistance); rv  is the coefficient of variations of the resistance model uncertainly. the value of this coefficient of variations can be obtained based on experimental results according to en 1990 (2006). for checking of the rc-structural system in accidental design situation, two main issues must be solved: (1) to calculate the pseudo-static response of the modified structural system under accidental loads; (2) to determined target value of the reliability index for accidental design (required level of reliability). 3. pseudo-static response of the structural system with a removed vertical load bearing elements. as was stated in ellingwood (2002) prevent and mitigation of progressive collapse can be achieved using two different methods: (1) tf-method (indirect tie-force method); (2) ap – method (direct alternate load path method). the indirect (tf method) consists of improving the structural integrity of building by providing redundancy of load path and ductile detailing. currently, the en 1991-1-7, allows the use of indirect method and some guidance is contained in the en 1992-1-1. in this case criteria are devised to check the local resistance to withstand a specific postulated accidental load. the direct method, referred to as “alternate load path” (ap method), is most widely used in the practical design and based on criteria for evaluating the capability of a damaged structure to bridge over or around the damaged volume of area without progressive collapse developing from the local damage. the ap-method consists in considering internal force (effect of the actions) redistributions throughout the structure following the loss of a vertical support element (ufc 4-023-03: 2010). as was shown in ufc 4-023-03 (2010), an ap-method analysis may be performed using of the following basic nonlinear procedures: nonlinear dynamic (nld) and nonlinear static (nls) procedures. in case of the nonlinear static procedure after materially-and-geometrically nonlinear model is built, the accidental load combination are magnified by a dynamic increase factor (dif) that accounts for inertia effects and the resulting load is applied to model with removed vertical load bearing elements. if a dynamic increase factor (dif) is known, for deformationcontrolled actions, the resulting deformations are compared to the expected deformation capacities; for the force controlled action, the member strength is not modified and shell not be less than the maximum internal member forces (demands). otherwise, calculation procedure based on the energetic approach should be used. the basic provisions of this procedure are described in detail in tur (2012). the purpose here is to analyze the structural response of rc-structural systems subjected to a sudden column loss. the procedure, which is used for obtaining of the pseudo-static nonlinear response of the structural system, consists of the following main steps: (1) calculate the static non-linear response “ f δ ” for the modified structural system with a removed vertical load bearing element according to certain rules (tur 2012, vlassis 2009) (see fig. 1, line 1); (2) calculate the pseudo-static response, that taking into account inertia effects, caused by suddenly applied gravity load. in general case, based on energetic consideration (see fig. 1): , 0 ( ) u ps u up d f      , (9) (9) pseudo-static response is equal: fig. 1. to assessment of the pseudo-static response of the structural system in accordance with (tur 2012, vlassis 2009) pseudo-static response is equal: , 0 1 ( ) u ps u u f p d       , (10) 4. required level of reliability for accidental design situation. in general case, the probability of structure collapse due to postulated abnormal event can be written as: ( ) ( ) ( ) ( )i i ip f p f dh p d h p h , (11) as was shown in ellingwood (2002), in a “specific local resistance” design strategy, the focus is on minimizing probability ( )ip f dh , that is, to minimize the likelihood of initiation of damage that may lead to progressive collapse. this strategy may be difficult or uneconomical, and may leave some significant hazards unaddressed. accordingly, it is likely that ( )ip d h will very close to 1,0 in many practical cases, meaning that the collapse probability becomes, approximately: ( ) ( ) ( )i ip f p f dh p h , (12) it is in minimizing the conditional probability ( )ip f h , that the science and art of the structural engineer becomes paramount (ellingwood 2002). it may be assumed that the occurrence of the abnormal event ih can be modeled as a poisson process with yearly mean rate of occurrence i . the probability of occurrence of this abnormal event during some reference period t, is thus approximately ( )i ip h t  (for very small i ) (ellingwood 2002). in the case of fire, gas explosion and some other accidental loads, parameter i may be related to building floor area ( i fp a   , in which fa floor area and 1 2p p p  , where term 1p  probability of occurrence of hazard per unit area and 2 1.0p  represents effect of warning and control systems). mean rates of occurrence for gas explosions, bomb explosions and vehicular collisions in accordance with (ellingwood and corotis 1991) are approximately: gas explosions (per dwelling): 2x10-5/yr; bomb explosions (per dwelling): 2x10-6/yr; vehicular collisions (per dwelling): 6x10-4/yr; full developed fire (per building): 5x10-8/yr. as it was shown in (ellingwood 2002), to evaluate ( )ip f dh , one must postulate a mathematical model, g(x) (state model), of the structural system based on principles of mechanics and supplemented, where possible, with experimental data (!). the load and resistance variables are expressed by vector x. we must then determine the probability distribution of each variable and integrate the joint density function of x over that region of probability space where g(x) <0 to compute in accordance with en 1990 conventional limit state probability. but, we must to remember that it is very difficult and complex way (especially for structural systems). alternatively, form – analysis may be used to compute a conditional reliability index  defined as: g g     , (13) where: g and g  is mean and standard deviation of g(x). according to ellingwood (2002), the reliability index is related to ( )ip f dh through: -1[ ( )]ip f dh   , (14) in which -1[ ( )]ip f dh is the percent-point function of the standard normal probability distribution. with ( )i ip h t  , eq. (14) can be rewritten as: -1[ ( / )]ip f t    , (15) as was shown in ellingwood (2002), the first-generation probability-based limit state design criteria (such as, for example, eurocodes) all are based, to varying degrees, on reliability of individual structural members and components. however, to implement reliability-based design criteria against progressive collapse in practice sense, the limit state probability (or reliability index) must be evaluated for a structural system (!). in contrast to member reliability, (10) in general case, the probability of structure collapse due to postulated abnormal event can be written as: fig. 1. to assessment of the pseudo-static response of the structural system in accordance with (tur 2012, vlassis 2009) pseudo-static response is equal: , 0 1 ( ) u ps u u f p d       , (10) 4. required level of reliability for accidental design situation. in general case, the probability of structure collapse due to postulated abnormal event can be written as: ( ) ( ) ( ) ( )i i ip f p f dh p d h p h , (11) as was shown in ellingwood (2002), in a “specific local resistance” design strategy, the focus is on minimizing probability ( )ip f dh , that is, to minimize the likelihood of initiation of damage that may lead to progressive collapse. this strategy may be difficult or uneconomical, and may leave some significant hazards unaddressed. accordingly, it is likely that ( )ip d h will very close to 1,0 in many practical cases, meaning that the collapse probability becomes, approximately: ( ) ( ) ( )i ip f p f dh p h , (12) it is in minimizing the conditional probability ( )ip f h , that the science and art of the structural engineer becomes paramount (ellingwood 2002). it may be assumed that the occurrence of the abnormal event ih can be modeled as a poisson process with yearly mean rate of occurrence i . the probability of occurrence of this abnormal event during some reference period t, is thus approximately ( )i ip h t  (for very small i ) (ellingwood 2002). in the case of fire, gas explosion and some other accidental loads, parameter i may be related to building floor area ( i fp a   , in which fa floor area and 1 2p p p  , where term 1p  probability of occurrence of hazard per unit area and 2 1.0p  represents effect of warning and control systems). mean rates of occurrence for gas explosions, bomb explosions and vehicular collisions in accordance with (ellingwood and corotis 1991) are approximately: gas explosions (per dwelling): 2x10-5/yr; bomb explosions (per dwelling): 2x10-6/yr; vehicular collisions (per dwelling): 6x10-4/yr; full developed fire (per building): 5x10-8/yr. as it was shown in (ellingwood 2002), to evaluate ( )ip f dh , one must postulate a mathematical model, g(x) (state model), of the structural system based on principles of mechanics and supplemented, where possible, with experimental data (!). the load and resistance variables are expressed by vector x. we must then determine the probability distribution of each variable and integrate the joint density function of x over that region of probability space where g(x) <0 to compute in accordance with en 1990 conventional limit state probability. but, we must to remember that it is very difficult and complex way (especially for structural systems). alternatively, form – analysis may be used to compute a conditional reliability index  defined as: g g     , (13) where: g and g  is mean and standard deviation of g(x). according to ellingwood (2002), the reliability index is related to ( )ip f dh through: -1[ ( )]ip f dh   , (14) in which -1[ ( )]ip f dh is the percent-point function of the standard normal probability distribution. with ( )i ip h t  , eq. (14) can be rewritten as: -1[ ( / )]ip f t    , (15) as was shown in ellingwood (2002), the first-generation probability-based limit state design criteria (such as, for example, eurocodes) all are based, to varying degrees, on reliability of individual structural members and components. however, to implement reliability-based design criteria against progressive collapse in practice sense, the limit state probability (or reliability index) must be evaluated for a structural system (!). in contrast to member reliability, (11) as was shown in ellingwood (2002), in a “specific local resistance” design strategy, the focus is on minimizing probability ( )ip f dh , that is, to minimize the likelihood of initiation of damage that may lead to progressive collapse. this strategy may be difficult or uneconomical, and may leave some significant hazards unaddressed. accordingly, it is likely that ( )ip d h will very close to 1,0 in many practical cases, meaning that the collapse probability becomes, approximately: fig. 1. to assessment of the pseudo-static response of the structural system in accordance with (tur 2012, vlassis 2009) pseudo-static response is equal: , 0 1 ( ) u ps u u f p d       , (10) 4. required level of reliability for accidental design situation. in general case, the probability of structure collapse due to postulated abnormal event can be written as: ( ) ( ) ( ) ( )i i ip f p f dh p d h p h , (11) as was shown in ellingwood (2002), in a “specific local resistance” design strategy, the focus is on minimizing probability ( )ip f dh , that is, to minimize the likelihood of initiation of damage that may lead to progressive collapse. this strategy may be difficult or uneconomical, and may leave some significant hazards unaddressed. accordingly, it is likely that ( )ip d h will very close to 1,0 in many practical cases, meaning that the collapse probability becomes, approximately: ( ) ( ) ( )i ip f p f dh p h , (12) it is in minimizing the conditional probability ( )ip f h , that the science and art of the structural engineer becomes paramount (ellingwood 2002). it may be assumed that the occurrence of the abnormal event ih can be modeled as a poisson process with yearly mean rate of occurrence i . the probability of occurrence of this abnormal event during some reference period t, is thus approximately ( )i ip h t  (for very small i ) (ellingwood 2002). in the case of fire, gas explosion and some other accidental loads, parameter i may be related to building floor area ( i fp a   , in which fa floor area and 1 2p p p  , where term 1p  probability of occurrence of hazard per unit area and 2 1.0p  represents effect of warning and control systems). mean rates of occurrence for gas explosions, bomb explosions and vehicular collisions in accordance with (ellingwood and corotis 1991) are approximately: gas explosions (per dwelling): 2x10-5/yr; bomb explosions (per dwelling): 2x10-6/yr; vehicular collisions (per dwelling): 6x10-4/yr; full developed fire (per building): 5x10-8/yr. as it was shown in (ellingwood 2002), to evaluate ( )ip f dh , one must postulate a mathematical model, g(x) (state model), of the structural system based on principles of mechanics and supplemented, where possible, with experimental data (!). the load and resistance variables are expressed by vector x. we must then determine the probability distribution of each variable and integrate the joint density function of x over that region of probability space where g(x) <0 to compute in accordance with en 1990 conventional limit state probability. but, we must to remember that it is very difficult and complex way (especially for structural systems). alternatively, form – analysis may be used to compute a conditional reliability index  defined as: g g     , (13) where: g and g  is mean and standard deviation of g(x). according to ellingwood (2002), the reliability index is related to ( )ip f dh through: -1[ ( )]ip f dh   , (14) in which -1[ ( )]ip f dh is the percent-point function of the standard normal probability distribution. with ( )i ip h t  , eq. (14) can be rewritten as: -1[ ( / )]ip f t    , (15) as was shown in ellingwood (2002), the first-generation probability-based limit state design criteria (such as, for example, eurocodes) all are based, to varying degrees, on reliability of individual structural members and components. however, to implement reliability-based design criteria against progressive collapse in practice sense, the limit state probability (or reliability index) must be evaluated for a structural system (!). in contrast to member reliability, (12) it is in minimizing the conditional probability ( )ip f h , that the science and art of the structural engineer becomes paramount (ellingwood 2002). it may be assumed that the occurrence of the abnormal event ih can be modeled as a poisson process with yearly mean rate of occurrence iλ . the probability of occurrence of this abnormal event during some reference period t, is thus approximately ( )i ip h t= λ (for very small iλ ) (ellingwood 2002). in the case of fire, gas explosion and some other accidental loads, parameter iλ may be related to building floor area ( i fp aλ = ⋅ , in which fa floor area and 1 2p p p= ⋅ , where term 1p – probability of occurrence of hazard per unit area and 2 1.0p < represents effect of warning and control systems). mean rates of occurrence for gas explosions, bomb explosions and vehicular collisions in accordance with (ellingwood and corotis 1991) are approximately: _ gas explosions (per dwelling): 2x10-5/yr; _ bomb explosions (per dwelling): 2x10-6/yr; _ vehicular collisions (per dwelling): 6x10-4/yr; _ full developed fire (per building): 5x10-8/yr. as it was shown in (ellingwood 2002), to evaluate ( )ip f dh , one must postulate a mathematical model, g(x) (state model), of the structural system based on principles of mechanics and supplemented, where possible, with experimental data (!). the load and resistance variables are expressed by vector x. we must then determine the probability distribution of each variable and integrate the joint density function of x over that region of probability space where g(x) <0 required level of reliability for accidental design situation 81 journal of sustainable architecture and civil engineering 2018/1/22 to compute in accordance with en 1990 conventional limit state probability. but, we must to remember that it is very difficult and complex way (especially for structural systems). alternatively, form – analysis may be used to compute a conditional reliability index β defined as: fig. 1. to assessment of the pseudo-static response of the structural system in accordance with (tur 2012, vlassis 2009) pseudo-static response is equal: , 0 1 ( ) u ps u u f p d       , (10) 4. required level of reliability for accidental design situation. in general case, the probability of structure collapse due to postulated abnormal event can be written as: ( ) ( ) ( ) ( )i i ip f p f dh p d h p h , (11) as was shown in ellingwood (2002), in a “specific local resistance” design strategy, the focus is on minimizing probability ( )ip f dh , that is, to minimize the likelihood of initiation of damage that may lead to progressive collapse. this strategy may be difficult or uneconomical, and may leave some significant hazards unaddressed. accordingly, it is likely that ( )ip d h will very close to 1,0 in many practical cases, meaning that the collapse probability becomes, approximately: ( ) ( ) ( )i ip f p f dh p h , (12) it is in minimizing the conditional probability ( )ip f h , that the science and art of the structural engineer becomes paramount (ellingwood 2002). it may be assumed that the occurrence of the abnormal event ih can be modeled as a poisson process with yearly mean rate of occurrence i . the probability of occurrence of this abnormal event during some reference period t, is thus approximately ( )i ip h t  (for very small i ) (ellingwood 2002). in the case of fire, gas explosion and some other accidental loads, parameter i may be related to building floor area ( i fp a   , in which fa floor area and 1 2p p p  , where term 1p  probability of occurrence of hazard per unit area and 2 1.0p  represents effect of warning and control systems). mean rates of occurrence for gas explosions, bomb explosions and vehicular collisions in accordance with (ellingwood and corotis 1991) are approximately: gas explosions (per dwelling): 2x10-5/yr; bomb explosions (per dwelling): 2x10-6/yr; vehicular collisions (per dwelling): 6x10-4/yr; full developed fire (per building): 5x10-8/yr. as it was shown in (ellingwood 2002), to evaluate ( )ip f dh , one must postulate a mathematical model, g(x) (state model), of the structural system based on principles of mechanics and supplemented, where possible, with experimental data (!). the load and resistance variables are expressed by vector x. we must then determine the probability distribution of each variable and integrate the joint density function of x over that region of probability space where g(x) <0 to compute in accordance with en 1990 conventional limit state probability. but, we must to remember that it is very difficult and complex way (especially for structural systems). alternatively, form – analysis may be used to compute a conditional reliability index  defined as: g g     , (13) where: g and g  is mean and standard deviation of g(x). according to ellingwood (2002), the reliability index is related to ( )ip f dh through: -1[ ( )]ip f dh   , (14) in which -1[ ( )]ip f dh is the percent-point function of the standard normal probability distribution. with ( )i ip h t  , eq. (14) can be rewritten as: -1[ ( / )]ip f t    , (15) as was shown in ellingwood (2002), the first-generation probability-based limit state design criteria (such as, for example, eurocodes) all are based, to varying degrees, on reliability of individual structural members and components. however, to implement reliability-based design criteria against progressive collapse in practice sense, the limit state probability (or reliability index) must be evaluated for a structural system (!). in contrast to member reliability, (13) where: gµ and gσ – is mean and standard deviation of g(x). according to ellingwood (2002), the reliability index is related to ( )ip f dh through: fig. 1. to assessment of the pseudo-static response of the structural system in accordance with (tur 2012, vlassis 2009) pseudo-static response is equal: , 0 1 ( ) u ps u u f p d       , (10) 4. required level of reliability for accidental design situation. in general case, the probability of structure collapse due to postulated abnormal event can be written as: ( ) ( ) ( ) ( )i i ip f p f dh p d h p h , (11) as was shown in ellingwood (2002), in a “specific local resistance” design strategy, the focus is on minimizing probability ( )ip f dh , that is, to minimize the likelihood of initiation of damage that may lead to progressive collapse. this strategy may be difficult or uneconomical, and may leave some significant hazards unaddressed. accordingly, it is likely that ( )ip d h will very close to 1,0 in many practical cases, meaning that the collapse probability becomes, approximately: ( ) ( ) ( )i ip f p f dh p h , (12) it is in minimizing the conditional probability ( )ip f h , that the science and art of the structural engineer becomes paramount (ellingwood 2002). it may be assumed that the occurrence of the abnormal event ih can be modeled as a poisson process with yearly mean rate of occurrence i . the probability of occurrence of this abnormal event during some reference period t, is thus approximately ( )i ip h t  (for very small i ) (ellingwood 2002). in the case of fire, gas explosion and some other accidental loads, parameter i may be related to building floor area ( i fp a   , in which fa floor area and 1 2p p p  , where term 1p  probability of occurrence of hazard per unit area and 2 1.0p  represents effect of warning and control systems). mean rates of occurrence for gas explosions, bomb explosions and vehicular collisions in accordance with (ellingwood and corotis 1991) are approximately: gas explosions (per dwelling): 2x10-5/yr; bomb explosions (per dwelling): 2x10-6/yr; vehicular collisions (per dwelling): 6x10-4/yr; full developed fire (per building): 5x10-8/yr. as it was shown in (ellingwood 2002), to evaluate ( )ip f dh , one must postulate a mathematical model, g(x) (state model), of the structural system based on principles of mechanics and supplemented, where possible, with experimental data (!). the load and resistance variables are expressed by vector x. we must then determine the probability distribution of each variable and integrate the joint density function of x over that region of probability space where g(x) <0 to compute in accordance with en 1990 conventional limit state probability. but, we must to remember that it is very difficult and complex way (especially for structural systems). alternatively, form – analysis may be used to compute a conditional reliability index  defined as: g g     , (13) where: g and g  is mean and standard deviation of g(x). according to ellingwood (2002), the reliability index is related to ( )ip f dh through: -1[ ( )]ip f dh   , (14) in which -1[ ( )]ip f dh is the percent-point function of the standard normal probability distribution. with ( )i ip h t  , eq. (14) can be rewritten as: -1[ ( / )]ip f t    , (15) as was shown in ellingwood (2002), the first-generation probability-based limit state design criteria (such as, for example, eurocodes) all are based, to varying degrees, on reliability of individual structural members and components. however, to implement reliability-based design criteria against progressive collapse in practice sense, the limit state probability (or reliability index) must be evaluated for a structural system (!). in contrast to member reliability, (14) in which -1[ ( )]ip f dhφ is the percent-point function of the standard normal probability distribution. with ( )i ip h t= λ , eq. (14) can be rewritten as: fig. 1. to assessment of the pseudo-static response of the structural system in accordance with (tur 2012, vlassis 2009) pseudo-static response is equal: , 0 1 ( ) u ps u u f p d       , (10) 4. required level of reliability for accidental design situation. in general case, the probability of structure collapse due to postulated abnormal event can be written as: ( ) ( ) ( ) ( )i i ip f p f dh p d h p h , (11) as was shown in ellingwood (2002), in a “specific local resistance” design strategy, the focus is on minimizing probability ( )ip f dh , that is, to minimize the likelihood of initiation of damage that may lead to progressive collapse. this strategy may be difficult or uneconomical, and may leave some significant hazards unaddressed. accordingly, it is likely that ( )ip d h will very close to 1,0 in many practical cases, meaning that the collapse probability becomes, approximately: ( ) ( ) ( )i ip f p f dh p h , (12) it is in minimizing the conditional probability ( )ip f h , that the science and art of the structural engineer becomes paramount (ellingwood 2002). it may be assumed that the occurrence of the abnormal event ih can be modeled as a poisson process with yearly mean rate of occurrence i . the probability of occurrence of this abnormal event during some reference period t, is thus approximately ( )i ip h t  (for very small i ) (ellingwood 2002). in the case of fire, gas explosion and some other accidental loads, parameter i may be related to building floor area ( i fp a   , in which fa floor area and 1 2p p p  , where term 1p  probability of occurrence of hazard per unit area and 2 1.0p  represents effect of warning and control systems). mean rates of occurrence for gas explosions, bomb explosions and vehicular collisions in accordance with (ellingwood and corotis 1991) are approximately: gas explosions (per dwelling): 2x10-5/yr; bomb explosions (per dwelling): 2x10-6/yr; vehicular collisions (per dwelling): 6x10-4/yr; full developed fire (per building): 5x10-8/yr. as it was shown in (ellingwood 2002), to evaluate ( )ip f dh , one must postulate a mathematical model, g(x) (state model), of the structural system based on principles of mechanics and supplemented, where possible, with experimental data (!). the load and resistance variables are expressed by vector x. we must then determine the probability distribution of each variable and integrate the joint density function of x over that region of probability space where g(x) <0 to compute in accordance with en 1990 conventional limit state probability. but, we must to remember that it is very difficult and complex way (especially for structural systems). alternatively, form – analysis may be used to compute a conditional reliability index  defined as: g g     , (13) where: g and g  is mean and standard deviation of g(x). according to ellingwood (2002), the reliability index is related to ( )ip f dh through: -1[ ( )]ip f dh   , (14) in which -1[ ( )]ip f dh is the percent-point function of the standard normal probability distribution. with ( )i ip h t  , eq. (14) can be rewritten as: -1[ ( / )]ip f t    , (15) as was shown in ellingwood (2002), the first-generation probability-based limit state design criteria (such as, for example, eurocodes) all are based, to varying degrees, on reliability of individual structural members and components. however, to implement reliability-based design criteria against progressive collapse in practice sense, the limit state probability (or reliability index) must be evaluated for a structural system (!). in contrast to member reliability, (15) as was shown in ellingwood (2002), the first-generation probability-based limit state design criteria (such as, for example, eurocodes) all are based, to varying degrees, on reliability of individual structural members and components. however, to implement reliability-based design criteria against progressive collapse in practice sense, the limit state probability (or reliability index) must be evaluated for a structural system (!). in contrast to member reliability, this evaluation is difficult (!) even at the present state of art and with computational resources available (ellingwood 2002, tur 2012). assuming that an analysis of a damaged structure can be performed, an acceptable value of β upon which to base design for conditional limit states is suggested by eq. (15). as shown by ellingwood (2002), the probability of structural system failure is an order of magnitude less, depending on the redundancy in the system and the degree continuity between members. for example, if 610i −λ = to 10-5, than the conditional failure probability for the structural system should be on the order of 10-2…10-1, and the target value of reliability index tagβ should be the order of 1,5. load and resistance criteria can be developed to be consistent with the reliability. at the first stage of analysis the value of the global resistance factor rγ was defined in accordance with (sykora and holicky 2011) from eq. (7). as it was shown above, the ecov-method is based on idea that the random distribution of resistance, which is again described by the coefficient variation vr, can be estimated from mean rm and characteristic rk values of resistance (pseudo-static response of the structural system). in this case, coefficient variations of resistance vr can be obtained from following equation: this evaluation is difficult (!) even at the present state of art and with computational resources available (ellingwood 2002, tur 2012). assuming that an analysis of a damaged structure can be performed, an acceptable value of  upon which to base design for conditional limit states is suggested by eq. (15). as shown by ellingwood (2002), the probability of structural system failure is an order of magnitude less, depending on the redundancy in the system and the degree continuity between members. for example, if 610i   to 10-5, than the conditional failure probability for the structural system should be on the order of 10-2…10-1, and the target value of reliability index tag should be the order of 1,5. load and resistance criteria can be developed to be consistent with the reliability. 5. assessment of the global resistance and global safety factors for pseudo-static response. at the first stage of analysis the value of the global resistance factor r was defined in accordance with (sykora and holicky 2011) from eq. (7). as it was shown above, the ecov-method is based on idea that the random distribution of resistance, which is again described by the coefficient variation vr, can be estimated from mean rm and characteristic rk values of resistance (pseudo-static response of the structural system). in this case, coefficient variations of resistance vr can be obtained from following equation: 1 ln( ) 1, 64 m r k r v r  , (16) where: ,m kr r  are the mean and characteristic values of resistance (pseudo-static response, as was shown in section 3), obtained by two separate non-linear analysis using mean and characteristic values of input material parameters respectively. the results of the nonlinear analysis of the statically undetermined an encastre rc-beam and values of the coefficient variations vr and global resistance coefficient r obtained by calculations are presented in table 1. table 1. the results of estimation the coefficient r based on ecov element l ' l r r [%] resistance, kn/m 1 ln( ) 1, 64 m r k r v r  exp(1, 2 )r rv  rm rk rc-beam (an encastre) 0,48 1,05 119,5 109,4 0,054 1,07 notes: materials properties: concrete class c25/30, fcm=33 mpa, steel b500, fym=1,1fyk=550 mpa; section 300x350 mm; 1, 5tag  for accidental design situation. the result, presented in table 1 was obtained with fem-computer program most widely used in practical design and declared about possibilities for nonlinear analysis of reinforced concrete structures. as it was declared in software manual, fe-program is capable of a “realistic simulation of rc-structure” behavior in the entire loading range with ductile as well as brittle failure modes (sykora and holicky 2011, schlune et al. 2011). as was shown in allaix and mancini (2007) the result of investigation depends on assumption and criteria underlying the model used in the non-linear analysis. it should be noted that the different fem-programs (software), which applied for nonlinear structural analysis, will have own different level of fem-model uncertainties in addition to local cross-section resistance model, material and geometry uncertainties. clearly, the approach is meaningful if structural model covers all relevant failure mechanisms. so, effects of model uncertainties should be treated separately (!). at the second stage of analysis the coefficient of variations rv of the computer model uncertainties was assessed based on theoretical background described in annex d (en 1990: 2006). from these features, it is suggested to be derived from the comparison of the experimental tests data and numerical calculations results, but though probabilistic consideration. the set of the test results obtained in experimental investigations of the different types of statically indeterminate structures demonstrates different failure mechanism (see tables 2, 3) was collected from some references and used for assessment of the coefficient variations rv and model uncertainly factor rd . the model uncertainty factor rd takes into account difference between the real behavior of structure and the results of a numerical modeling suitable for specific structure. the real properties of the material and specimens geometry characteristics obtained by testing were used as an input data for nonlinear analysis. the main characteristics of the analyzed test specimens are presented in tables 2, 3. as it can be seen from the table 4, the estimated values of coefficient of variations vrd for model uncertainties are much higher than recommended in codes (for example, in fib mc2010, values in range 1,05…1,1). (16) where: ,m kr r – are the mean and characteristic values of resistance (pseudo-static response, as was shown in section 3), obtained by two separate non-linear analysis using mean and characteristic values of input material parameters respectively. the results of the nonlinear analysis of the statically undetermined an encastre rc-beam and values of the coefficient variations vr and global resistance coefficient rγ obtained by calculations are presented in table 1. the result, presented in table 1 was obtained with fem-computer program most widely used in practical design and declared about possibilities for nonlinear analysis of reinforced concrete assessment of the global resistance and global safety factors for pseudostatic response journal of sustainable architecture and civil engineering 2018/1/22 82 structures. as it was declared in software manual, fe-program is capable of a “realistic simulation of rc-structure” behavior in the entire loading range with ductile as well as brittle failure modes (sykora and holicky 2011, schlune et al. 2011). as was shown in allaix and mancini (2007) the result of investigation depends on assumption and criteria underlying the model used in the non-linear analysis. it should be noted that the different fem-programs (software), which applied for nonlinear structural analysis, will have own different level of fem-model uncertainties in addition to local cross-section resistance model, material and geometry uncertainties. clearly, the approach is meaningful if structural model covers all relevant failure mechanisms. so, effects of model uncertainties should be treated separately (!). table 1 the results of estimation the coefficient rγ based on ecov element l ' l r r [%] resistance, kn/m 1 ln( ) 1, 64 m r k r v r = exp(1, 2 )r rvγ = rm rk rc-beam (an encastre) 0,48 1,05 119,5 109,4 0,054 1,07 notes: materials properties: concrete class c25/30, fcm=33 mpa, steel b500, fym=1,1fyk=550 mpa; section 300x350 mm; 1, 5tagβ = for accidental design situation. table 2 loading arrangement for experimental specimens loading scheme beam, slabs series reference the same results and conclusions were obtained by schlune et al. (2011). schlune concluded that model uncertainties of nonlinear analysis are much higher than in standard design based on engineering formulas and are strongly dependent on modes of failure and adopted failure criteria. reported in schlune et al. (2011) coefficient of variation due to model uncertainty for bending failure in range 5…30%, for shear 15…64%. schlune concluded that due to the lack of data, the choice of model uncertainty often depends on engineering judgment and can be subjective. table 2. loading arrangement for experimental specimens loading scheme beam, slabs series reference b1, b2, b3 monnier (1970) b4, b6, b7, b8, b9 saleh and barem (2013), ashour and habeeb (2008), maghsoudi and bengar (2009), mahmoud and afefy (2012), dalfré and barros (2011) b5 saleh and barem (2013) b10, b11, b13 farhangvesali et al. (2013), parmar et al. (2015) b12 qian and li (2012) b14, b15 rashidian et al. (2016) slab s7, s11, s12, s15, s16, s17, s27, s28, s33 cardenas and sozen (1968) cylindrical shell sh11, sh31 duddeck et. al. (1978) note, that coefficient of variations vm due to material uncertainty (variability) has not a fixed value. in the case of concrete, the mean value of the concrete compressive strength for different classes according to en 1992-2 (2005) is calculated as: fcm=fck+8 mpa (where 8 1, 64 cmpa   , which standard deviation 4, 88c mpa  ). for fixed value of standard deviation (as a basic characteristic of the production quality control) 4, 5c mpa  , coefficient of variation vm,c of concrete compressive strength will be in range from 8,6 % (c50/60) to 21 % (c16/20) and coefficient of variation for materials vm will be in range from vm=10,48 % to 21,84 % (with fixed value of coefficient of variations vs=6 % for steel). b1, b2, b3 monnier (1970) the same results and conclusions were obtained by schlune et al. (2011). schlune concluded that model uncertainties of nonlinear analysis are much higher than in standard design based on engineering formulas and are strongly dependent on modes of failure and adopted failure criteria. reported in schlune et al. (2011) coefficient of variation due to model uncertainty for bending failure in range 5…30%, for shear 15…64%. schlune concluded that due to the lack of data, the choice of model uncertainty often depends on engineering judgment and can be subjective. table 2. loading arrangement for experimental specimens loading scheme beam, slabs series reference b1, b2, b3 monnier (1970) b4, b6, b7, b8, b9 saleh and barem (2013), ashour and habeeb (2008), maghsoudi and bengar (2009), mahmoud and afefy (2012), dalfré and barros (2011) b5 saleh and barem (2013) b10, b11, b13 farhangvesali et al. (2013), parmar et al. (2015) b12 qian and li (2012) b14, b15 rashidian et al. (2016) slab s7, s11, s12, s15, s16, s17, s27, s28, s33 cardenas and sozen (1968) cylindrical shell sh11, sh31 duddeck et. al. (1978) note, that coefficient of variations vm due to material uncertainty (variability) has not a fixed value. in the case of concrete, the mean value of the concrete compressive strength for different classes according to en 1992-2 (2005) is calculated as: fcm=fck+8 mpa (where 8 1, 64 cmpa   , which standard deviation 4, 88c mpa  ). for fixed value of standard deviation (as a basic characteristic of the production quality control) 4, 5c mpa  , coefficient of variation vm,c of concrete compressive strength will be in range from 8,6 % (c50/60) to 21 % (c16/20) and coefficient of variation for materials vm will be in range from vm=10,48 % to 21,84 % (with fixed value of coefficient of variations vs=6 % for steel). b4, b6, b7, b8, b9 saleh and barem (2013), ashour and habeeb (2008), maghsoudi and bengar (2009), mahmoud and afefy (2012), dalfré and barros (2011) the same results and conclusions were obtained by schlune et al. (2011). schlune concluded that model uncertainties of nonlinear analysis are much higher than in standard design based on engineering formulas and are strongly dependent on modes of failure and adopted failure criteria. reported in schlune et al. (2011) coefficient of variation due to model uncertainty for bending failure in range 5…30%, for shear 15…64%. schlune concluded that due to the lack of data, the choice of model uncertainty often depends on engineering judgment and can be subjective. table 2. loading arrangement for experimental specimens loading scheme beam, slabs series reference b1, b2, b3 monnier (1970) b4, b6, b7, b8, b9 saleh and barem (2013), ashour and habeeb (2008), maghsoudi and bengar (2009), mahmoud and afefy (2012), dalfré and barros (2011) b5 saleh and barem (2013) b10, b11, b13 farhangvesali et al. (2013), parmar et al. (2015) b12 qian and li (2012) b14, b15 rashidian et al. (2016) slab s7, s11, s12, s15, s16, s17, s27, s28, s33 cardenas and sozen (1968) cylindrical shell sh11, sh31 duddeck et. al. (1978) note, that coefficient of variations vm due to material uncertainty (variability) has not a fixed value. in the case of concrete, the mean value of the concrete compressive strength for different classes according to en 1992-2 (2005) is calculated as: fcm=fck+8 mpa (where 8 1, 64 cmpa   , which standard deviation 4, 88c mpa  ). for fixed value of standard deviation (as a basic characteristic of the production quality control) 4, 5c mpa  , coefficient of variation vm,c of concrete compressive strength will be in range from 8,6 % (c50/60) to 21 % (c16/20) and coefficient of variation for materials vm will be in range from vm=10,48 % to 21,84 % (with fixed value of coefficient of variations vs=6 % for steel). b5 saleh and barem (2013) the same results and conclusions were obtained by schlune et al. (2011). schlune concluded that model uncertainties of nonlinear analysis are much higher than in standard design based on engineering formulas and are strongly dependent on modes of failure and adopted failure criteria. reported in schlune et al. (2011) coefficient of variation due to model uncertainty for bending failure in range 5…30%, for shear 15…64%. schlune concluded that due to the lack of data, the choice of model uncertainty often depends on engineering judgment and can be subjective. table 2. loading arrangement for experimental specimens loading scheme beam, slabs series reference b1, b2, b3 monnier (1970) b4, b6, b7, b8, b9 saleh and barem (2013), ashour and habeeb (2008), maghsoudi and bengar (2009), mahmoud and afefy (2012), dalfré and barros (2011) b5 saleh and barem (2013) b10, b11, b13 farhangvesali et al. (2013), parmar et al. (2015) b12 qian and li (2012) b14, b15 rashidian et al. (2016) slab s7, s11, s12, s15, s16, s17, s27, s28, s33 cardenas and sozen (1968) cylindrical shell sh11, sh31 duddeck et. al. (1978) note, that coefficient of variations vm due to material uncertainty (variability) has not a fixed value. in the case of concrete, the mean value of the concrete compressive strength for different classes according to en 1992-2 (2005) is calculated as: fcm=fck+8 mpa (where 8 1, 64 cmpa   , which standard deviation 4, 88c mpa  ). for fixed value of standard deviation (as a basic characteristic of the production quality control) 4, 5c mpa  , coefficient of variation vm,c of concrete compressive strength will be in range from 8,6 % (c50/60) to 21 % (c16/20) and coefficient of variation for materials vm will be in range from vm=10,48 % to 21,84 % (with fixed value of coefficient of variations vs=6 % for steel). b10, b11, b13 farhangvesali et al. (2013), parmar et al. (2015) the same results and conclusions were obtained by schlune et al. (2011). schlune concluded that model uncertainties of nonlinear analysis are much higher than in standard design based on engineering formulas and are strongly dependent on modes of failure and adopted failure criteria. reported in schlune et al. (2011) coefficient of variation due to model uncertainty for bending failure in range 5…30%, for shear 15…64%. schlune concluded that due to the lack of data, the choice of model uncertainty often depends on engineering judgment and can be subjective. table 2. loading arrangement for experimental specimens loading scheme beam, slabs series reference b1, b2, b3 monnier (1970) b4, b6, b7, b8, b9 saleh and barem (2013), ashour and habeeb (2008), maghsoudi and bengar (2009), mahmoud and afefy (2012), dalfré and barros (2011) b5 saleh and barem (2013) b10, b11, b13 farhangvesali et al. (2013), parmar et al. (2015) b12 qian and li (2012) b14, b15 rashidian et al. (2016) slab s7, s11, s12, s15, s16, s17, s27, s28, s33 cardenas and sozen (1968) cylindrical shell sh11, sh31 duddeck et. al. (1978) note, that coefficient of variations vm due to material uncertainty (variability) has not a fixed value. in the case of concrete, the mean value of the concrete compressive strength for different classes according to en 1992-2 (2005) is calculated as: fcm=fck+8 mpa (where 8 1, 64 cmpa   , which standard deviation 4, 88c mpa  ). for fixed value of standard deviation (as a basic characteristic of the production quality control) 4, 5c mpa  , coefficient of variation vm,c of concrete compressive strength will be in range from 8,6 % (c50/60) to 21 % (c16/20) and coefficient of variation for materials vm will be in range from vm=10,48 % to 21,84 % (with fixed value of coefficient of variations vs=6 % for steel). b12 qian and li (2012) the same results and conclusions were obtained by schlune et al. (2011). schlune concluded that model uncertainties of nonlinear analysis are much higher than in standard design based on engineering formulas and are strongly dependent on modes of failure and adopted failure criteria. reported in schlune et al. (2011) coefficient of variation due to model uncertainty for bending failure in range 5…30%, for shear 15…64%. schlune concluded that due to the lack of data, the choice of model uncertainty often depends on engineering judgment and can be subjective. table 2. loading arrangement for experimental specimens loading scheme beam, slabs series reference b1, b2, b3 monnier (1970) b4, b6, b7, b8, b9 saleh and barem (2013), ashour and habeeb (2008), maghsoudi and bengar (2009), mahmoud and afefy (2012), dalfré and barros (2011) b5 saleh and barem (2013) b10, b11, b13 farhangvesali et al. (2013), parmar et al. (2015) b12 qian and li (2012) b14, b15 rashidian et al. (2016) slab s7, s11, s12, s15, s16, s17, s27, s28, s33 cardenas and sozen (1968) cylindrical shell sh11, sh31 duddeck et. al. (1978) note, that coefficient of variations vm due to material uncertainty (variability) has not a fixed value. in the case of concrete, the mean value of the concrete compressive strength for different classes according to en 1992-2 (2005) is calculated as: fcm=fck+8 mpa (where 8 1, 64 cmpa   , which standard deviation 4, 88c mpa  ). for fixed value of standard deviation (as a basic characteristic of the production quality control) 4, 5c mpa  , coefficient of variation vm,c of concrete compressive strength will be in range from 8,6 % (c50/60) to 21 % (c16/20) and coefficient of variation for materials vm will be in range from vm=10,48 % to 21,84 % (with fixed value of coefficient of variations vs=6 % for steel). b14, b15 rashidian et al. (2016) slab s7, s11, s12, s15, s16, s17, s27, s28, s33 cardenas and sozen (1968) cylindrical shell sh11, sh31 duddeck et. al. (1978) 83 journal of sustainable architecture and civil engineering 2018/1/22 at the second stage of analysis the coefficient of variations rvϑ of the computer model uncertainties was assessed based on theoretical background described in annex d (en 1990: 2006). from these features, it is suggested to be derived from the comparison of the experimental tests data and numerical calculations results, but though probabilistic consideration. the set of the test results obtained in experimental investigations of the different types of statically indeterminate structures demonstrates different failure mechanism (see tables 2, 3) was table 3 basic parameters of the experimental specimens (input data for non-linear analysis)b ea m /s la b s er ie s cross-section dimensions size, mm material properties b h zs lr ' lr concrete steel fcm fctm, mpa ecm, gpa fym, mpa es, gpa 1 2 3 4 5 6 7 8 9 10 11 b1 table 3. basic parameters of the experimental specimens (input data for non-linear analysis) beam /slab series cross-section dimensions size, mm material properties b h zs lr ' lr concrete steel fcm fctm, mpa ecm, gpa fym, mpa es, gpa 1 2 3 4 5 6 7 8 9 10 11 b1 150 260 236 0,64 0,91 34,4 4,51 32 440 200 b2 0,91 0,64 32,4 3,95 31,9 435 b3 0,91 0,64 33,9 4,41 33,5 433 b4 250 210 0,66 0,46 28 2,5 28 520 (ø10) 580 (ø12) b5 29 2,64 b6 200 300 265 0,85 0,85 26,6 28,3 511 b7 150 250 170 1,28 1,28 74,2 48,3 412 b8 250 210 0,46 1,17 25 28 445 b9 375 120 68 0,64 1,85 30,1 31,5 447 b10 180 180 118 0,59 0,59 30,5 31,6 592 b11 59 54,3 550 b12 100 180 150 0,87 0,87 40 41,2 575 b13 900 150 130 1,06 0,83 33 28,9 450 b14, b15 200 140 90 0,66 0,44 26 1,5 28 530 s7 slabs 2290 105 1143 0,008 0,0086 35,5 33,7 345 s11 100 0,008 0,004 32,3 s12 100 0,008 0,004 35,6 s15 104 0,0079 0,0087 32,3 s16 105 0,008 0,0088 35,6 s17 100 0,0081 0,0088 35,2 s27 105 0,008 0,0087 35,5 s28 107 0,0081 0,0087 35,3 s33 101 0,008 0,0021 35,3 sh11 cylindrical shell 1677 5,02 447 0,611 0,611 43,0 2,0 16,4 670,0 201 sh31 5,0 0,895 0,326 table 4. estimated values of the global coefficient r structures shlune model allaix model coefficient of variation, % m r coeff. var., % factors vm* vg vrd vr vr0 vrd 0r rd r beams, frames var det 15,7 17,8… 30,6 1,004 1,55… 1,97 5,8 15,7 1,19 1,21 1,44 slabs var det 17,3 17,8… 30,6 1,03 1,52… 1,87 5,8 6,56 1,19 1,08 1,28 note: value of vm due to material variability in range from 8,6 % (c50/60) to vm=21 % (c16/20). further research is need to recommended appropriate values of the model uncertainty for numerical simulation. it should be noted, that for different fem-programs values of rd will be different. these values for fem-program 150 260 236 0,64 0,91 34,4 4,51 32 440 200 b2 0,91 0,64 32,4 3,95 31,9 435 b3 0,91 0,64 33,9 4,41 33,5 433 b4 250 210 0,66 0,46 28 2,5 28 520 (ø10) 580 (ø12)b5 29 2,64 b6 200 300 265 0,85 0,85 26,6 28,3 511 b7 150 250 170 1,28 1,28 74,2 48,3 412 b8 250 210 0,46 1,17 25 28 445 b9 375 120 68 0,64 1,85 30,1 31,5 447 b10 180 180 118 0,59 0,59 30,5 31,6 592 b11 59 54,3 550 b12 100 180 150 0,87 0,87 40 41,2 575 b13 900 150 130 1,06 0,83 33 28,9 450 b14, b15 200 140 90 0,66 0,44 26 1,5 28 530 s7 slabs 2290 105 1143 0,008 0,0086 35,5 33,7 345 s11 100 0,008 0,004 32,3 s12 100 0,008 0,004 35,6 s15 104 0,0079 0,0087 32,3 s16 105 0,008 0,0088 35,6 s17 100 0,0081 0,0088 35,2 s27 105 0,008 0,0087 35,5 s28 107 0,0081 0,0087 35,3 s33 101 0,008 0,0021 35,3 sh11 cylindrical shell 1677 5,02 447 0,611 0,611 43,0 2,0 16,4 670,0 201 sh31 5,0 0,895 0,326 journal of sustainable architecture and civil engineering 2018/1/22 84 collected from some references and used for assessment of the coefficient variations rvϑ and model uncertainly factor rdγ . the model uncertainty factor rdγ takes into account difference between the real behavior of structure and the results of a numerical modeling suitable for specific structure. the real properties of the material and specimens geometry characteristics obtained by testing were used as an input data for nonlinear analysis. the main characteristics of the analyzed test specimens are presented in tables 2, 3. as it can be seen from the table 4, the estimated values of coefficient of variations vrd for model uncertainties are much higher than recommended in codes (for example, in fib mc2010, values in range 1,05…1,1). the same results and conclusions were obtained by schlune et al. (2011). schlune concluded that model uncertainties of nonlinear analysis are much higher than in standard design based on engineering formulas and are strongly dependent on modes of failure and adopted failure criteria. reported in schlune et al. (2011) coefficient of variation due to model uncertainty for bending failure in range 5…30%, for shear 15…64%. schlune concluded that due to the lack of data, the choice of model uncertainty often depends on engineering judgment and can be subjective. note, that coefficient of variations vm due to material uncertainty (variability) has not a fixed value. in the case of concrete, the mean value of the concrete compressive strength for different classes according to en 1992-2 (2005) is calculated as: fcm=fck+8 mpa (where 8 1, 64 cmpa = σ , which standard deviation 4, 88c mpaσ = ). for fixed value of standard deviation (as a basic characteristic of the production quality control) 4, 5c mpaσ = , coefficient of variation vm,c of concrete compressive strength will be in range from 8,6 % (c50/60) to 21 % (c16/20) and coefficient of variation for materials vm will be in range from vm=10,48 % to 21,84 % (with fixed value of coefficient of variations vs=6 % for steel). table 4 estimated values of the global coefficient rγ s tr u ct u re s shlune model allaix model coefficient of variation, % mθ rγ coeff. var., % factors vm * vg vrd vr vr0 vrd 0rγ rdγ rγ beams, frames var det 15,7 17,8… 30,6 1,004 1,55… 1,97 5,8 15,7 1,19 1,21 1,44 slabs var det 17,3 17,8… 30,6 1,03 1,52… 1,87 5,8 6,56 1,19 1,08 1,28 note: value of vm due to material variability in range from 8,6 % (c50/60) to vm=21 % (c16/20). further research is need to recommended appropriate values of the model uncertainty for numerical simulation. it should be noted, that for different fem-programs values of rdγ will be different. these values for fem-program should be estimated based on full probabilistic approach, taking into account statistical parameters of the fem-model uncertainties and consists of in program manual. 85 journal of sustainable architecture and civil engineering 2018/1/22 fig. 2 some typical examples of the experimental and predicted forcedeflection response of the analyzed specimens (see tables 2, 3 for designation of the specimens) fig. 3 for estimatiation of the coefficient vr for fem-model (see with tables 2, 3) should be estimated based on full probabilistic approach, taking into account statistical parameters of the femmodel uncertainties and consists of in program manual. fig. 2. some typical examples of the experimental and predicted force-deflection response of the analyzed specimens (see tables 2, 3 for designation of the specimens) fig. 3. for estimatiation of the coefficient vr for fem-model (see with tables 2, 3) 6. conclusions. should be estimated based on full probabilistic approach, taking into account statistical parameters of the femmodel uncertainties and consists of in program manual. fig. 2. some typical examples of the experimental and predicted force-deflection response of the analyzed specimens (see tables 2, 3 for designation of the specimens) fig. 3. for estimatiation of the coefficient vr for fem-model (see with tables 2, 3) 6. conclusions. should be estimated based on full probabilistic approach, taking into account statistical parameters of the femmodel uncertainties and consists of in program manual. fig. 2. some typical examples of the experimental and predicted force-deflection response of the analyzed specimens (see tables 2, 3 for designation of the specimens) fig. 3. for estimatiation of the coefficient vr for fem-model (see with tables 2, 3) 6. conclusions. safety format suitable for nonlinear analysis (pseudo-static response) that based on global resistance in accordance with fib mc2010 concept are presented. the following conclusions can be adopt: (1) the differences between proposed methods are not significant; (2) fixed value of global safety factor 1, 27rγ = in accordance with fib mc2010 (2010) and en 1992-2 (2005) is not good approach for safety assessment and sometimes can be unconservative results; (3) the values of the global resistance factor rγ should be estimated separately for different computer programs, which are used for non-linear analysis (pseudo-static response conclusions journal of sustainable architecture and civil engineering 2018/1/22 86 of the structural system), based on experimental results. these values for separate computer programs should be estimated based on full probabilistic approach, taking into account statistical parameters of the fem-model uncertainties. for accidental design situation load and resistance criteria can be developed based on the target value of reliability index 1, 5tagβ = . allaix, d.l.; mancini g. 2007. assessment of a global resistance factor for reinforced concrete column by parametric analysis, in international symposium on innovation and sustainability of structures in civil engineering, 28–30 november, 2007, shanghai, china. allaix, d. l.; carbone v. i.; mancini g. 2013. global safety format for nonlinear analysis of analysis of reinforced concrete structures, structural concrete 14(1): 29–42. https://doi.org/10.1002/ suco.201200017 ashour, a. f.; habeeb, m. n. 2008. continuous concrete beams reinforced with cfrp bars, struct. build, sb6: 349-357. https://doi.org/10.1680/ stbu.2008.161.6.349 červenka, v. 2013a. global safety formats in fib model code 2010 for design of concrete structures, proceedings of the 11th probabilistic workshop, brno. červenka, v. 2013b. reliability – based non-linear analysis according to fib model code 2010, structures concrete, journal of the fib 14: 19-28. cardenas, a.; sozen, m. a. 1968. strength and behaviour of isotropically and nonisotropically reinforced concrete slabs subjected to combinations of flexural and torsional moments, university of illinois engineering experiment station. college of engineering. university of illinois at urbana-champaign. dalfré, g.; barros, j. a. 2011. assessing the effectiveness of a nsm-cfrp flexural strengthening technique for continuous rc slabs by experimental research, in first middle east conference on smart monitoring, assessment and rehabilitation of civil structures (smar), 2011, dubai. dod, u. s: 2009. design of building to resist progressive collapse. us department of defence, washington, dc, usa, unified facility criteria. ufc 4–023–03. duddeck, h.; griebenow, g.; shaper, g. 1978. material and time dependent nonlinear behaviour of cracked reinforced concrete slabs, nonlinear behaviour of reinforced concrete spatial structures 1: 101-113 ellingwood, b. r.; corotis, r. b. 1991. load combinations for buildings exposed to fires, engineering journal 28(1): 37-44. ellingwood, b. r. 2002. load and resistance factor criteria for progressive collapse design, in national workshop on prevention of progressive collapse rosemont: national institute of building sciences. en 1990: 2006. basic of structural design. en 1992-2: 2005. eurocode 2 – design of concrete structures. part 2: concrete bridges – design and detailing rules. farhangvesali, n.; valipour, h.; samali, b.; foster, s. 2013. development of arching action in longitudinally-restrained reinforced concrete beams, construction and building materials 47: 7-19. https://doi. org/10.1016/j.conbuildmat.2013.04.050 holicky, m. 2006. global resistance factor reinforced concrete members, acta politechnica, ctu in prague. hu, h. t.; schnobrich, w. c. 1991. nonlinear finite element analysis of reinforced concrete plates and shells under monotonic loading, computers & structures 38(5-6): 637-651. https://doi.org/10.1016/0045-7949(91)90015-e maghsoudi, a. a.; bengar, h. 2009. moment redistribution and ductility of rhsc continuous beams strengthened with cfrp, turkish journal of engineering and environmental sciences 33: 45-59. mahmoud, m.h.; afefy h.m.e.d. 2012. moment redistribution and ductility of rc continuous beams strengthened with cfrp strips, international journal of civil engineering research 3(3): 241-255. model code: 2010. first complete draft. volume 1-fib bulletin 55. volume 2-fib bulletin 56. issn 1562-3610. isbn 978-2-88394-095-6. international federation for structural concrete (fib), lausanne, switzerland. monnier, t. 1970. the moment-curvature relation of reinforced concrete, stevin-laboratory of the department of civil engineering, delft university of technology, reijswik (zh). parmar, g.; joshi, d.; patel, p. 2015. experimental investigation of rc beam-column assemblies under column removal scenario, nirma university journal of engineering and technology 3(1): 15-20. qian, k.; li, b. 2012. performance of three-dimensional reinforced concrete beam-column substructures under loss of a corner column scenario, journal references 87 journal of sustainable architecture and civil engineering 2018/1/22 of structural engineering 139(4): 584-594. https:// doi.org/10.1061/(asce)st.1943-541x.0000630 rashidian, o. et al. 2016. progressive collapse of exterior reinforced concrete beam–column sub-assemblages: considering the effects of a transverse frame, international journal of concrete structures and materials 10(4): 479-497. https://doi. org/10.1007/s40069-016-0167-2 saleh, a.; barem, a. 2013. experimental and theoretical analysis for behaviour of r.c. continuous beams strengthened by cfrp laminates, journal of babylon university/engineering sciences 21(5): 1555-1567. sangiorgio, f. 2015. safety format for non-linear analysis of rc structures subjected to multiple failure modes: doctoral dissertation, kth royal institute of technology. schlune, h.; plos, m.; gylltoft, k. 2011. safety format for the non-linear analysis of concrete structures, engineering structures 33(8). sykora, m.; holicky, m. 2011. safety format for nonlinear analysis in the model code – verification of reliability level. proceeding of fib symposium on concrete engineering for excellence and efficiency, prague, czech concrete society: 943-946. tur, a. 2012. the resistance of rc bending elements under suddenly applied load: doctoral thesis, brest state technical university. vecchio, f. j.; emara, m. b. 1992. shear deformations in reinforced concrete frames, aci structural journal 89(1): 46-56. vlassis, a. g. 2007. progressive collapse assessment of tall buildings: doctoral dissertation, imperial college london, university of london. yi, w. j.; he, q. f.; xiao, y.; kunnath, s. k. 2008. experimental study on progressive collapse-resistant behaviour of reinforced concrete frame structures, aci structural journal 105(4): 433. about the authors andrei tur assoc. professor, phd, engineer brest state technical university, faculty of civil engineering, department “building constructions” main research area robustness, nonlinear static and dynamic analysis of structures, reliability of building structures address 267, moskovskaya str., 224017, brest, belarus tel. +375 29 5253206 e-mail: aturphd@gmail.com victar tur professor, dsc, phd brest state technical university, faculty of civil engineering, department “technology of concrete and building materials” main research area self-stressing concrete structures, reliability of building structures address 267, moskovskaya str., 224017, brest, belarus tel. +375 33 6729404 e-mail: profturvic@gmail.com 39 journal of sustainable architecture and civil engineering 2018/2/23 *corresponding author: aurelija.levinskyte@ktu.lt the comparison of a numerical and empirical calculation of thermal transmittance of ventilated facade with different heat-conductive connections received 2018/07/08 accepted after revision 2018/09/18 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 39-48 doi 10.5755/j01.sace.23.2.21204 the comparison of a numerical and empirical calculation of thermal transmittance of ventilated facade with different heat-conductive connections jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.21204 aurelija levinskytė*, raimondas bliūdžius kaunas university of technology, institute of architecture and construction tunelio str. 60, lt-44405 kaunas, lithuania robertas kapačiūnas kaunas university of technology, facilities management, technical maintenance group k. donelaičio st. 73, lt-44249 kaunas, lithuania the energy efficient buildings are priority these days. the building energy efficiency requirements are increasing and thicker thermal insulation layer is used for building envelopes in order to achieve these high requirements. ventilated facades are often used for the construction of public buildings, whose thermal insulating layers are crossed with connections made from steel or aluminium alloy, whose influence on the heat transfer through the construction is high. looking for less heat-conductive materials for connections, it has been observed that different calculation methods give different results of heat transfer, depending on characteristics of materials for thermal insulation and connections. in order to find out the reasons for these differences, calculations of ventilated walls with various connections were carried out. the heat transfer through the wall with connections crossing thermal insulating layer could be calculated in two ways. the first way is simpler and was often used earlier this is the calculation of the heat transfer coefficient increase depending on type and geometry of connection using the formulas presented in the standards. a more precise calculation method is the calculation of the heat transfer coefficient of wall with connections using two dimensional and three dimensional heat transfer modelling computer software (heat flow analyses). the use of these two calculations methods shows the differences of results of the heat transfer through ventilated walls. for both calculations, the fragments of ventilated walls with connections made from aluminium alloy (λ 160 w/(m∙k)), zinc coated steel (λ 50 w/(m∙k)), stainless steel (λ 17 w/(m∙k)) and glass fiber reinforced plastic (λ – 0.23 w/(m∙k)) were created. calculations have shown that the heat transfer coefficient calculated for walls with zinc coated and stainless steel connections using different methods journal of sustainable architecture and civil engineering 2018/2/23 40 varies by 29 %, for walls with glass fiber reinforced plastic connections – by 0.4 % and for walls with aluminium alloy connections by 130 %. the main aim of this paper is the investigation of reasons of different calculations results according to numerical and empirical calculations methods. when the causes of discrepancies are found, empirical formulas can be corrected. keywords: heat-conductive connections, point thermal bridges, thermal insulation, ventilated facade systems. introduction energy use in residential and commercial buildings represents about 40% of the european union’s (eu) total final energy consumption and co2 emissions (european commission, 2008). this is the main reason for the higher requirements of the energy efficiency of buildings. therefore newly built buildings must be designed as energy efficient buildings today in lithuania as in other eu countries. the main tasks for reducing heat losses of buildings are improvement of the insulating properties of building envelopes, reduction of influence of thermal bridges, increase of airtightness of buildings, the use of efficient ventilation systems and others. according to review of literature, the influence of thermal bridges on building’s heat losses can be achieved from 5% to 39 % (quinten and feldheim 2016, ilomets et al. 2016, al-sanea and zedan 2012). correct design of thermal bridges is significant, because inefficiency solutions can be a cause of much higher heat losses of buildings. this is evidenced by the many studies carried out (cappelletti et al. 2011, misiopecki et al. 2018, ge et al. 2013, levinskyte et al. 2016). today ventilated facade system (fig. 1.) is often used for renovated and also for newly built buildings, which have higher requirements of energy efficiency. the steel, which is used as connectors in ventilated facade systems, has a thermal conductivity that may be over 1500 times higher than the thermal conductivity of insulating material. it has been shown that ignoring the effect of the steel connectors can lead to an over-estimate of the thermal resistance up to 50%, depending on the details of the construction (gorgolewski 2007). zalewski et al. (2010) quantified heat losses by thermal bridges in prefabricated building walls. the study showed the relative importance of the thermal bridges in the wall with steel frame increased by 26% comparing to wall without thermal bridges. for this reason point thermal bridges through heat-conductive connections in ventilated facade systems are also very significant and have to be correctly evaluated. fig. 1 example of ventilated facade system (plastic anchors are used to fixing of thermal insulation) (www.plantas.lt/ file/repository/ak_ lt(plantas).pdf 2018) fig. 1. example of ventilated facade system (plastic anchors are used to fixing of thermal insulation) (www.plantas.lt/file/repository/ak_lt(plantas).pdf 2018) 1anchors; 2 thermal break; 3 heat-conductive connections; 4screws; 5t profile; 6screws; 7 external panel; 8 thermal insulation+ wind barrier. the value of the point thermal bridge in ventilated facade systems depends on several parameters: the thickness and thermal conductivity of the thermal insulation material, the thickness and thermal conductivity of the load bearing layer of the wall, dimensions and the thermal conductivity of heat-conductive connections. also the thermal breaks are often used in practice, because they minimise the heat transfer between the heat-conductive connections and the load bearing wall. theodosiou et al. (2015) analysed thermal bridging on cladding systems and made calculations of this system with the thermal breaks and without them (fig.2.). the results of that study showed that the thermal break cannot provide a fully efficient measure against increased heat flow concentrated around the anchors penetrating the load bearing wall (theodosiou et al. 2015) as it is seen in fig.2 (b). fig. 2. the effect of braket type in the temperature distribution at the junction among the bracket with the substrate, in the case of (a) no thermal break and (b) thermal break existence (theodosiou et al. 2015) theodosiou et al. (2017) also had been making the research about thermal bridging effect on ventilated facades. authors analysed the influence of heat-conductive connections type on point thermal transmittance, calculated by finite element method using 3-d simulation software. in calculations different types of heat-conductive connections were used: two geometrical dimensions (full height and half height, as shown in fig.1.) and three different heat conductivity materials (synthetic  λ=0.20 w/(mꞏk), steel  λ=65 w/(mꞏk), chemical  λ=0.09 w/(mꞏk)) and also fragments of wall with thermal break and without them. as it can be seen from figure 3, the effect of the connections of all types increased in the cases of the full height connector without bracket and the high thermal conductivity of the material of load bearing wall. this figure also shows how the chemical connections, compared to others types of connections, can influence the decrease of the heat transfer through the insulated wall. the contribution of dimensions of connector to point thermal transmittance in all investigated cases is close to 10% (theodosiou et al. 2017). ventilated air gap 1− anchors; 2− thermal break; 3 − heat-conductive connections; 4 −screws; 5 −t profile; 6 − screws; 7 − external panel; 8 − thermal insulation+ wind barrier http://www.plantas.lt/file/repository/ak_lt(plantas).pdf http://www.plantas.lt/file/repository/ak_lt(plantas).pdf http://www.plantas.lt/file/repository/ak_lt(plantas).pdf 41 journal of sustainable architecture and civil engineering 2018/2/23 the value of the point thermal bridge in ventilated facade systems depends on several parameters: the thickness and thermal conductivity of the thermal insulation material, the thickness and thermal conductivity of the load bearing layer of the wall, dimensions and the thermal conductivity of heat-conductive connections. also the thermal breaks are often used in practice, because they minimise the heat transfer between the heat-conductive connections and the load bearing wall. theodosiou et al. (2015) analysed thermal bridging on cladding systems and made calculations of this system with the thermal breaks and without them (fig.2.). the results of that study showed that the thermal break cannot provide a fully efficient measure against increased heat flow concentrated around the anchors penetrating the load bearing wall (theodosiou et al. 2015) as it is seen in fig.2 (b). fig. 2 the effect of braket type in the temperature distribution at the junction among the bracket with the substrate, in the case of (a) no thermal break and (b) thermal break existence (theodosiou et al. 2015) fig. 1. example of ventilated facade system (plastic anchors are used to fixing of thermal insulation) (www.plantas.lt/file/repository/ak_lt(plantas).pdf 2018) 1anchors; 2 thermal break; 3 heat-conductive connections; 4screws; 5t profile; 6screws; 7 external panel; 8 thermal insulation+ wind barrier. the value of the point thermal bridge in ventilated facade systems depends on several parameters: the thickness and thermal conductivity of the thermal insulation material, the thickness and thermal conductivity of the load bearing layer of the wall, dimensions and the thermal conductivity of heat-conductive connections. also the thermal breaks are often used in practice, because they minimise the heat transfer between the heat-conductive connections and the load bearing wall. theodosiou et al. (2015) analysed thermal bridging on cladding systems and made calculations of this system with the thermal breaks and without them (fig.2.). the results of that study showed that the thermal break cannot provide a fully efficient measure against increased heat flow concentrated around the anchors penetrating the load bearing wall (theodosiou et al. 2015) as it is seen in fig.2 (b). fig. 2. the effect of braket type in the temperature distribution at the junction among the bracket with the substrate, in the case of (a) no thermal break and (b) thermal break existence (theodosiou et al. 2015) theodosiou et al. (2017) also had been making the research about thermal bridging effect on ventilated facades. authors analysed the influence of heat-conductive connections type on point thermal transmittance, calculated by finite element method using 3-d simulation software. in calculations different types of heat-conductive connections were used: two geometrical dimensions (full height and half height, as shown in fig.1.) and three different heat conductivity materials (synthetic  λ=0.20 w/(mꞏk), steel  λ=65 w/(mꞏk), chemical  λ=0.09 w/(mꞏk)) and also fragments of wall with thermal break and without them. as it can be seen from figure 3, the effect of the connections of all types increased in the cases of the full height connector without bracket and the high thermal conductivity of the material of load bearing wall. this figure also shows how the chemical connections, compared to others types of connections, can influence the decrease of the heat transfer through the insulated wall. the contribution of dimensions of connector to point thermal transmittance in all investigated cases is close to 10% (theodosiou et al. 2017). ventilated air gap fig. 1. example of ventilated facade system (plastic anchors are used to fixing of thermal insulation) (www.plantas.lt/file/repository/ak_lt(plantas).pdf 2018) 1anchors; 2 thermal break; 3 heat-conductive connections; 4screws; 5t profile; 6screws; 7 external panel; 8 thermal insulation+ wind barrier. the value of the point thermal bridge in ventilated facade systems depends on several parameters: the thickness and thermal conductivity of the thermal insulation material, the thickness and thermal conductivity of the load bearing layer of the wall, dimensions and the thermal conductivity of heat-conductive connections. also the thermal breaks are often used in practice, because they minimise the heat transfer between the heat-conductive connections and the load bearing wall. theodosiou et al. (2015) analysed thermal bridging on cladding systems and made calculations of this system with the thermal breaks and without them (fig.2.). the results of that study showed that the thermal break cannot provide a fully efficient measure against increased heat flow concentrated around the anchors penetrating the load bearing wall (theodosiou et al. 2015) as it is seen in fig.2 (b). fig. 2. the effect of braket type in the temperature distribution at the junction among the bracket with the substrate, in the case of (a) no thermal break and (b) thermal break existence (theodosiou et al. 2015) theodosiou et al. (2017) also had been making the research about thermal bridging effect on ventilated facades. authors analysed the influence of heat-conductive connections type on point thermal transmittance, calculated by finite element method using 3-d simulation software. in calculations different types of heat-conductive connections were used: two geometrical dimensions (full height and half height, as shown in fig.1.) and three different heat conductivity materials (synthetic  λ=0.20 w/(mꞏk), steel  λ=65 w/(mꞏk), chemical  λ=0.09 w/(mꞏk)) and also fragments of wall with thermal break and without them. as it can be seen from figure 3, the effect of the connections of all types increased in the cases of the full height connector without bracket and the high thermal conductivity of the material of load bearing wall. this figure also shows how the chemical connections, compared to others types of connections, can influence the decrease of the heat transfer through the insulated wall. the contribution of dimensions of connector to point thermal transmittance in all investigated cases is close to 10% (theodosiou et al. 2017). ventilated air gap theodosiou et al. (2017) also had been making the research about thermal bridging effect on ventilated facades. authors analysed the influence of heat-conductive connections type on point thermal transmittance, calculated by finite element method using 3-d simulation software. in calculations different types of heat-conductive connections were used: two geometrical dimensions (full height and half height, as shown in fig.1.) and three different heat conductivity materials (synthetic − λ=0.20 w/(m∙k), steel − λ=65 w/(m∙k), chemical − λ=0.09 w/(m∙k)) and also fragments of wall with thermal break and without them. as it can be seen from fig. 3, the effect of the connections of all types increased in the cases of the full height connector without bracket and the high thermal conductivity of the material of load bearing wall. this figure also shows how the chemical connections, compared to others types of connections, can influence the decrease of the heat transfer through the insulated wall. the contribution of dimensions of connector to point thermal transmittance in all investigated cases is close to 10% (theodosiou et al. 2017). sadauskiene et al. (2015) developed a simplified methodology for evaluation of influence of point thermal bridges created by aluminium alloy connections on energy performance of walls insulatfig. 3 point thermal transmittance (χ-value) as a function of connector material for various wall materials and for both examined connectors sizes (theodosiou et al. 2017) fig. 3. point thermal transmittance (χ-value) as a function of connector material for various wall materials and for both examined connectors sizes (theodosiou et al. 2017) sadauskiene et al. (2015) developed a simplified methodology for evaluation of influence of point thermal bridges created by aluminium alloy connections on energy performance of walls insulated according to passive house requirements. their investigation showed that the highest influences on the point thermal transmittance (χ, (w/k)) and thermal transmittance (u, (w/m²ꞏk)) of the entire wall are the thermal conductivity of the material of load bearing wall and the thickness of the insulating layer. the thermal transmittance of the entire wall depending on these options may differ up to 35% (sadauskiene et al. 2015). the general functional dependency may be expressed as follows (sadauskiene et al. 2015): � � ��𝜆𝜆�,𝑑𝑑�,𝜆𝜆�,𝑑𝑑�� (1) where: λl thermal conductivity of the material of load bearing wall, w/mꞏk; dl thickness of the load bearing wall, m); λt thermal conductivity of thermal insulating material, w/mꞏk; dt thickness of the thermal insulating layer, mm. a system of equations was produced by authors (sadauskiene et al. 2015): � � � ����� � ��������𝜆𝜆��,������������������������������� � 𝜆𝜆� � � ����� � �����𝑑𝑑������������������������������������ � 𝑑𝑑� � ��� ����� � �����𝜆𝜆����������������������������� � 𝜆𝜆� � ����� ����� � �����𝑑𝑑��������������������������������� � 𝑑𝑑� � ��� (2) the solution of this system gives a mathematical expression according which the point thermal transmittance could be calculated with aluminium alloy connections: � � ����� � ��������𝜆𝜆�� � �����𝑑𝑑� � �����𝜆𝜆� � �����𝑑𝑑� (3) the authors claim that a simplified calculation using the empirical relationship is a sufficiently precise (95%). analysis of literature showed that evaluation of point thermal bridges in ventilated facade systems with heat-conductive connections is multiparametrical and often quite complicated, especially when there is no possibility to use 3-d simulation software. in this case, a simplified calculation methodology (sadauskiene et al. 2015) can be used, which is based on the requirements of the standard en iso 10211 (2017). however the review of literature did not reveal the situation of using of two standard calculation methods and differences between the results according to them. therefore, the main purpose of this study is to analyse the two standard calculation methods when different heat conductivity connectors are used and determine the reasons of different results between these methods. 2. methodology 2.1. the standard calculations methods there are two standard ways to calculate the heat transfer through fragments of buildings envelopes when heat conductive connections are used. the three dimensional nature of the point thermal bridge effect on thermal performance of ventilated systems require a detailed calculation approach in order to take into account the complex geometry and the great differences in thermo physical properties of adjacent materials (theodosiou 2017). according to the en iso 10211 the temperature distribution within, and the heat flow through a construction can be calculated if the boundary conditions and constructional details are known. therefore the geometrical model is divided into a number of adjacent material cells, each a) b) journal of sustainable architecture and civil engineering 2018/2/23 42 ed according to passive house requirements. their investigation showed that the highest influences on the point thermal transmittance (χ, (w/k)) and thermal transmittance (u, (w/m²∙k)) of the entire wall are the thermal conductivity of the material of load bearing wall and the thickness of the insulating layer. the thermal transmittance of the entire wall depending on these options may differ up to 35% (sadauskiene et al. 2015). the general functional dependency may be expressed as follows (sadauskiene et al. 2015): fig. 3. point thermal transmittance (χ-value) as a function of connector material for various wall materials and for both examined connectors sizes (theodosiou et al. 2017) sadauskiene et al. (2015) developed a simplified methodology for evaluation of influence of point thermal bridges created by aluminium alloy connections on energy performance of walls insulated according to passive house requirements. their investigation showed that the highest influences on the point thermal transmittance (χ, (w/k)) and thermal transmittance (u, (w/m²ꞏk)) of the entire wall are the thermal conductivity of the material of load bearing wall and the thickness of the insulating layer. the thermal transmittance of the entire wall depending on these options may differ up to 35% (sadauskiene et al. 2015). the general functional dependency may be expressed as follows (sadauskiene et al. 2015): � � ��𝜆𝜆�,𝑑𝑑�,𝜆𝜆�,𝑑𝑑�� (1) where: λl thermal conductivity of the material of load bearing wall, w/mꞏk; dl thickness of the load bearing wall, m); λt thermal conductivity of thermal insulating material, w/mꞏk; dt thickness of the thermal insulating layer, mm. a system of equations was produced by authors (sadauskiene et al. 2015): � � � ����� � ��������𝜆𝜆��,������������������������������� � 𝜆𝜆� � � ����� � �����𝑑𝑑������������������������������������ � 𝑑𝑑� � ��� ����� � �����𝜆𝜆����������������������������� � 𝜆𝜆� � ����� ����� � �����𝑑𝑑��������������������������������� � 𝑑𝑑� � ��� (2) the solution of this system gives a mathematical expression according which the point thermal transmittance could be calculated with aluminium alloy connections: � � ����� � ��������𝜆𝜆�� � �����𝑑𝑑� � �����𝜆𝜆� � �����𝑑𝑑� (3) the authors claim that a simplified calculation using the empirical relationship is a sufficiently precise (95%). analysis of literature showed that evaluation of point thermal bridges in ventilated facade systems with heat-conductive connections is multiparametrical and often quite complicated, especially when there is no possibility to use 3-d simulation software. in this case, a simplified calculation methodology (sadauskiene et al. 2015) can be used, which is based on the requirements of the standard en iso 10211 (2017). however the review of literature did not reveal the situation of using of two standard calculation methods and differences between the results according to them. therefore, the main purpose of this study is to analyse the two standard calculation methods when different heat conductivity connectors are used and determine the reasons of different results between these methods. 2. methodology 2.1. the standard calculations methods there are two standard ways to calculate the heat transfer through fragments of buildings envelopes when heat conductive connections are used. the three dimensional nature of the point thermal bridge effect on thermal performance of ventilated systems require a detailed calculation approach in order to take into account the complex geometry and the great differences in thermo physical properties of adjacent materials (theodosiou 2017). according to the en iso 10211 the temperature distribution within, and the heat flow through a construction can be calculated if the boundary conditions and constructional details are known. therefore the geometrical model is divided into a number of adjacent material cells, each (1) λl thermal conductivity of the material of load bearing wall, w/m∙k; dl thickness of the load bearing wall, m); λt thermal conductivity of thermal insulating material, w/m∙k; dt thickness of the thermal insulating layer, mm. a system of equations was produced by authors (sadauskiene et al. 2015): fig. 3. point thermal transmittance (χ-value) as a function of connector material for various wall materials and for both examined connectors sizes (theodosiou et al. 2017) sadauskiene et al. (2015) developed a simplified methodology for evaluation of influence of point thermal bridges created by aluminium alloy connections on energy performance of walls insulated according to passive house requirements. their investigation showed that the highest influences on the point thermal transmittance (χ, (w/k)) and thermal transmittance (u, (w/m²ꞏk)) of the entire wall are the thermal conductivity of the material of load bearing wall and the thickness of the insulating layer. the thermal transmittance of the entire wall depending on these options may differ up to 35% (sadauskiene et al. 2015). the general functional dependency may be expressed as follows (sadauskiene et al. 2015): � � ��𝜆𝜆�,𝑑𝑑�,𝜆𝜆�,𝑑𝑑�� (1) where: λl thermal conductivity of the material of load bearing wall, w/mꞏk; dl thickness of the load bearing wall, m); λt thermal conductivity of thermal insulating material, w/mꞏk; dt thickness of the thermal insulating layer, mm. a system of equations was produced by authors (sadauskiene et al. 2015): � � � ����� � ��������𝜆𝜆��,������������������������������� � 𝜆𝜆� � � ����� � �����𝑑𝑑������������������������������������ � 𝑑𝑑� � ��� ����� � �����𝜆𝜆����������������������������� � 𝜆𝜆� � ����� ����� � �����𝑑𝑑��������������������������������� � 𝑑𝑑� � ��� (2) the solution of this system gives a mathematical expression according which the point thermal transmittance could be calculated with aluminium alloy connections: � � ����� � ��������𝜆𝜆�� � �����𝑑𝑑� � �����𝜆𝜆� � �����𝑑𝑑� (3) the authors claim that a simplified calculation using the empirical relationship is a sufficiently precise (95%). analysis of literature showed that evaluation of point thermal bridges in ventilated facade systems with heat-conductive connections is multiparametrical and often quite complicated, especially when there is no possibility to use 3-d simulation software. in this case, a simplified calculation methodology (sadauskiene et al. 2015) can be used, which is based on the requirements of the standard en iso 10211 (2017). however the review of literature did not reveal the situation of using of two standard calculation methods and differences between the results according to them. therefore, the main purpose of this study is to analyse the two standard calculation methods when different heat conductivity connectors are used and determine the reasons of different results between these methods. 2. methodology 2.1. the standard calculations methods there are two standard ways to calculate the heat transfer through fragments of buildings envelopes when heat conductive connections are used. the three dimensional nature of the point thermal bridge effect on thermal performance of ventilated systems require a detailed calculation approach in order to take into account the complex geometry and the great differences in thermo physical properties of adjacent materials (theodosiou 2017). according to the en iso 10211 the temperature distribution within, and the heat flow through a construction can be calculated if the boundary conditions and constructional details are known. therefore the geometrical model is divided into a number of adjacent material cells, each (2) the solution of this system gives a mathematical expression according which the point thermal transmittance could be calculated with aluminium alloy connections: fig. 3. point thermal transmittance (χ-value) as a function of connector material for various wall materials and for both examined connectors sizes (theodosiou et al. 2017) sadauskiene et al. (2015) developed a simplified methodology for evaluation of influence of point thermal bridges created by aluminium alloy connections on energy performance of walls insulated according to passive house requirements. their investigation showed that the highest influences on the point thermal transmittance (χ, (w/k)) and thermal transmittance (u, (w/m²ꞏk)) of the entire wall are the thermal conductivity of the material of load bearing wall and the thickness of the insulating layer. the thermal transmittance of the entire wall depending on these options may differ up to 35% (sadauskiene et al. 2015). the general functional dependency may be expressed as follows (sadauskiene et al. 2015): � � ��𝜆𝜆�,𝑑𝑑�,𝜆𝜆�,𝑑𝑑�� (1) where: λl thermal conductivity of the material of load bearing wall, w/mꞏk; dl thickness of the load bearing wall, m); λt thermal conductivity of thermal insulating material, w/mꞏk; dt thickness of the thermal insulating layer, mm. a system of equations was produced by authors (sadauskiene et al. 2015): � � � ����� � ��������𝜆𝜆��,������������������������������� � 𝜆𝜆� � � ����� � �����𝑑𝑑������������������������������������ � 𝑑𝑑� � ��� ����� � �����𝜆𝜆����������������������������� � 𝜆𝜆� � ����� ����� � �����𝑑𝑑��������������������������������� � 𝑑𝑑� � ��� (2) the solution of this system gives a mathematical expression according which the point thermal transmittance could be calculated with aluminium alloy connections: � � ����� � ��������𝜆𝜆�� � �����𝑑𝑑� � �����𝜆𝜆� � �����𝑑𝑑� (3) the authors claim that a simplified calculation using the empirical relationship is a sufficiently precise (95%). analysis of literature showed that evaluation of point thermal bridges in ventilated facade systems with heat-conductive connections is multiparametrical and often quite complicated, especially when there is no possibility to use 3-d simulation software. in this case, a simplified calculation methodology (sadauskiene et al. 2015) can be used, which is based on the requirements of the standard en iso 10211 (2017). however the review of literature did not reveal the situation of using of two standard calculation methods and differences between the results according to them. therefore, the main purpose of this study is to analyse the two standard calculation methods when different heat conductivity connectors are used and determine the reasons of different results between these methods. 2. methodology 2.1. the standard calculations methods there are two standard ways to calculate the heat transfer through fragments of buildings envelopes when heat conductive connections are used. the three dimensional nature of the point thermal bridge effect on thermal performance of ventilated systems require a detailed calculation approach in order to take into account the complex geometry and the great differences in thermo physical properties of adjacent materials (theodosiou 2017). according to the en iso 10211 the temperature distribution within, and the heat flow through a construction can be calculated if the boundary conditions and constructional details are known. therefore the geometrical model is divided into a number of adjacent material cells, each (3) the authors claim that a simplified calculation using the empirical relationship is a sufficiently precise (95%). analysis of literature showed that evaluation of point thermal bridges in ventilated facade systems with heat-conductive connections is multiparametrical and often quite complicated, especially when there is no possibility to use 3-d simulation software. in this case, a simplified calculation methodology (sadauskiene et al. 2015) can be used, which is based on the requirements of the standard en iso 10211 (2017). however the review of literature did not reveal the situation of using of two standard calculation methods and differences between the results according to them. therefore, the main purpose of this study is to analyse the two standard calculation methods when different heat conductivity connectors are used and determine the reasons of different results between these methods. the standard calculations methods there are two standard ways to calculate the heat transfer through fragments of buildings envelopes when heat conductive connections are used. the three dimensional nature of the point thermal bridge effect on thermal performance of ventilated systems require a detailed calculation approach in order to take into account the complex geometry and the great differences in thermo physical properties of adjacent materials (theodosiou 2017). according to the en iso 10211 the temperature distribution within, and the heat flow through a construction can be calculated if the boundary conditions and constructional details are known. therefore the geometrical model is divided into a number of adjacent material cells, each with a homogenous thermal conductivity. the effect of mechanical fasteners can be assessed by calculations in accordance with en iso 10211 (2017) in order to obtain the point thermal transmittance, χ, due to one fastener calculated according to en iso 6946. the correction to the thermal transmittance is given by: with a homogenous thermal conductivity. the effect of mechanical fasteners can be assessed by calculations in accordance with en iso 10211 (2017) in order to obtain the point thermal transmittance, χ, due to one fastener calculated according to en iso 6946. the correction to the thermal transmittance is given by: ∆𝑈𝑈� � 𝑛𝑛� ∙ 𝜒𝜒 (4) where: 𝑛𝑛� the number of fasteners per m². 𝜒𝜒 ��the point thermal transmittance, are determined by: 𝜒𝜒 � 𝐿𝐿�� � ∑ 𝑈𝑈� ∙ 𝐴𝐴������ � ∑ ψ� ∙ 𝑙𝑙� �� ��� ; (5) where: 𝐿𝐿�� the thermal coupling coefficient obtained from 3-d calculation of the 3-d component separating the two environments being considered; 𝑈𝑈� the thermal transmittance of the 1-d component i separating the two environments being considered; 𝐴𝐴� the area over which the value 𝑈𝑈� applies; ψ� linear thermal transmittance; 𝑙𝑙� the length over which the value ψ�applies; 𝑁𝑁� the number of 2-d components; 𝑁𝑁� the number of 1-d components. the standard en iso 10211 (2017) explains modelling conditions and calculation method of the heat transmission coefficients. so using 3-d simulation software heat3, which is validated against the standard en iso 10211 (2017), the model of envelope fragments was created. the model was 600 mm wide and 600 mm high with one "l" shape heat-conductive connection in the middle. the model was split into finite elements. maximum numerical cells 𝑁𝑁� � �� were applied in xdirection, y-direction and z-direction. then boundary conditions were attributed to the internal surface and the external surface of the wall fragments. according to the en 6946 (2017) thermal resistance of internal surface is 0.13 (m²∙k)/w and the same thermal resistance value 0.13 (m²∙k)/w of surface located in front of the ventilated air gap. temperature difference through the fragment was 1 k. after calculations, the heat flow through the envelope fragment was obtained and using that value the heat transfer coefficient u was calculated. the standard en iso 6946 (2017) provides an approximate method that can be used for elements containing inhomogeneous layers, including the effect of metal connectors, by means of a correction term (en iso 6946 2017). the correction to the thermal transmittance is given by: ∆𝑈𝑈� � � ∙ ��∙��∙���� ∙ � �� ���� �� (6) where: � � ��� if fastener fully penetrates the insulation layer; � � ��� � ���� in the case of recessed fastener; 𝜆𝜆� thermal conductivity of the fastener (w/(mꞏk)); 𝑛𝑛� the number of fasteners per m²; 𝐴𝐴� the cross-sectional area of one fastener (m²); 𝑑𝑑� the thickness of the insulation layer containing the fastener (m); 𝑑𝑑� the length of the fastener that penetrates the insulation layer (m); 𝑅𝑅� the thermal resistance of the insulation layer penetrated by the fasteners (m²ꞏk/w); 𝑅𝑅��� the total thermal resistance of the component ignoring any thermal bridging. the calculation method according to en 6946 (2017) does not estimate the influence of steel screw fastening the "l" shape connection to the load bearing wall layer. for calculation of the heat transfer coefficient of envelope fragment, according to this method, the total resistance of all fragment layers is calculated and the correction of the thermal transmittance according to eq.6 is added. 2.2. parameters of elements of wall fragments for empirical calculation and numerical simulation since the thickness and conductivity of thermal insulation are some of the most significant parameters for value of point thermal transmittance, this calculation is carried out in accordance with two methodologies by changing these parameters. the ventilated facade systems with four different thermal conductivity connections were chosen for the calculations (fig.4.). the conductivity of glass fiber reinforced plastic connectors is 0.23 w/(mꞏk), stainless steel connectors  17 w/(mꞏk), zinc coated steel connectors  50 w/(mꞏk), and aluminium alloy connectors  160 w/(mꞏk). “l” shape connectors were chosen, because that shape is commonly used in practice. the thickness of all kind of these connectors was 3 mm, width − 100 mm, a part connected to wall − 50 mm. total length of the connector through the insulation layer was in accordance with the thickness of the thermal insulation layer. there were used 2.78 pcs of connectors per 1m² in calculations. also four thicknesses of thermal insulation were used: 200 mm, 300 mm, 330 mm and 400 mm. two types of thermal insulation materials were chosen with different thermal conductivity: 0.036 w/(mꞏk) and 0.040 w/(mꞏk). the load bearing wall was the same in all cases. the thermal conductivity of load bearing wall was 0.7 w/(mꞏk) like ceramic brick masonry and the thickness of this wall was 250 mm. finishing layer on the inner side of the envelope was 15 mm thick plaster with thermal conductivity 0.882 w/(mꞏk). all other fastening elements like screws in the ventilated facade system were steel elements (λ=50 w/(mꞏk)). they were simulated as square cross section elements (7 mm x 7 mm), whereas only square elements could be drawing in heat3 software. all of calculations were performed in two cases. the first of them was with thermal break between load bearing wall and connectors, and the second one without thermal break. thermal conductivity of that break was 0.17 w/(mꞏk). dimensions of thermal break are the same like base of "l" shape connections (50 mm x 100 mm) with 5 mm thickness. (4) where: nf − the number of fasteners per m². with a homogenous thermal conductivity. the effect of mechanical fasteners can be assessed by calculations in accordance with en iso 10211 (2017) in order to obtain the point thermal transmittance, χ, due to one fastener calculated according to en iso 6946. the correction to the thermal transmittance is given by: ∆𝑈𝑈� � 𝑛𝑛� ∙ 𝜒𝜒 (4) where: 𝑛𝑛� the number of fasteners per m². 𝜒𝜒 ��the point thermal transmittance, are determined by: 𝜒𝜒 � 𝐿𝐿�� � ∑ 𝑈𝑈� ∙ 𝐴𝐴������ � ∑ ψ� ∙ 𝑙𝑙� �� ��� ; (5) where: 𝐿𝐿�� the thermal coupling coefficient obtained from 3-d calculation of the 3-d component separating the two environments being considered; 𝑈𝑈� the thermal transmittance of the 1-d component i separating the two environments being considered; 𝐴𝐴� the area over which the value 𝑈𝑈� applies; ψ� linear thermal transmittance; 𝑙𝑙� the length over which the value ψ�applies; 𝑁𝑁� the number of 2-d components; 𝑁𝑁� the number of 1-d components. the standard en iso 10211 (2017) explains modelling conditions and calculation method of the heat transmission coefficients. so using 3-d simulation software heat3, which is validated against the standard en iso 10211 (2017), the model of envelope fragments was created. the model was 600 mm wide and 600 mm high with one "l" shape heat-conductive connection in the middle. the model was split into finite elements. maximum numerical cells 𝑁𝑁� � �� were applied in xdirection, y-direction and z-direction. then boundary conditions were attributed to the internal surface and the external surface of the wall fragments. according to the en 6946 (2017) thermal resistance of internal surface is 0.13 (m²∙k)/w and the same thermal resistance value 0.13 (m²∙k)/w of surface located in front of the ventilated air gap. temperature difference through the fragment was 1 k. after calculations, the heat flow through the envelope fragment was obtained and using that value the heat transfer coefficient u was calculated. the standard en iso 6946 (2017) provides an approximate method that can be used for elements containing inhomogeneous layers, including the effect of metal connectors, by means of a correction term (en iso 6946 2017). the correction to the thermal transmittance is given by: ∆𝑈𝑈� � � ∙ ��∙��∙���� ∙ � �� ���� �� (6) where: � � ��� if fastener fully penetrates the insulation layer; � � ��� � ���� in the case of recessed fastener; 𝜆𝜆� thermal conductivity of the fastener (w/(mꞏk)); 𝑛𝑛� the number of fasteners per m²; 𝐴𝐴� the cross-sectional area of one fastener (m²); 𝑑𝑑� the thickness of the insulation layer containing the fastener (m); 𝑑𝑑� the length of the fastener that penetrates the insulation layer (m); 𝑅𝑅� the thermal resistance of the insulation layer penetrated by the fasteners (m²ꞏk/w); 𝑅𝑅��� the total thermal resistance of the component ignoring any thermal bridging. the calculation method according to en 6946 (2017) does not estimate the influence of steel screw fastening the "l" shape connection to the load bearing wall layer. for calculation of the heat transfer coefficient of envelope fragment, according to this method, the total resistance of all fragment layers is calculated and the correction of the thermal transmittance according to eq.6 is added. 2.2. parameters of elements of wall fragments for empirical calculation and numerical simulation since the thickness and conductivity of thermal insulation are some of the most significant parameters for value of point thermal transmittance, this calculation is carried out in accordance with two methodologies by changing these parameters. the ventilated facade systems with four different thermal conductivity connections were chosen for the calculations (fig.4.). the conductivity of glass fiber reinforced plastic connectors is 0.23 w/(mꞏk), stainless steel connectors  17 w/(mꞏk), zinc coated steel connectors  50 w/(mꞏk), and aluminium alloy connectors  160 w/(mꞏk). “l” shape connectors were chosen, because that shape is commonly used in practice. the thickness of all kind of these connectors was 3 mm, width − 100 mm, a part connected to wall − 50 mm. total length of the connector through the insulation layer was in accordance with the thickness of the thermal insulation layer. there were used 2.78 pcs of connectors per 1m² in calculations. also four thicknesses of thermal insulation were used: 200 mm, 300 mm, 330 mm and 400 mm. two types of thermal insulation materials were chosen with different thermal conductivity: 0.036 w/(mꞏk) and 0.040 w/(mꞏk). the load bearing wall was the same in all cases. the thermal conductivity of load bearing wall was 0.7 w/(mꞏk) like ceramic brick masonry and the thickness of this wall was 250 mm. finishing layer on the inner side of the envelope was 15 mm thick plaster with thermal conductivity 0.882 w/(mꞏk). all other fastening elements like screws in the ventilated facade system were steel elements (λ=50 w/(mꞏk)). they were simulated as square cross section elements (7 mm x 7 mm), whereas only square elements could be drawing in heat3 software. all of calculations were performed in two cases. the first of them was with thermal break between load bearing wall and connectors, and the second one without thermal break. thermal conductivity of that break was 0.17 w/(mꞏk). dimensions of thermal break are the same like base of "l" shape connections (50 mm x 100 mm) with 5 mm thickness. the point thermal transmittance, are determined by: methodology 43 journal of sustainable architecture and civil engineering 2018/2/23 with a homogenous thermal conductivity. the effect of mechanical fasteners can be assessed by calculations in accordance with en iso 10211 (2017) in order to obtain the point thermal transmittance, χ, due to one fastener calculated according to en iso 6946. the correction to the thermal transmittance is given by: ∆𝑈𝑈� � 𝑛𝑛� ∙ 𝜒𝜒 (4) where: 𝑛𝑛� the number of fasteners per m². 𝜒𝜒 ��the point thermal transmittance, are determined by: 𝜒𝜒 � 𝐿𝐿�� � ∑ 𝑈𝑈� ∙ 𝐴𝐴������ � ∑ ψ� ∙ 𝑙𝑙� �� ��� ; (5) where: 𝐿𝐿�� the thermal coupling coefficient obtained from 3-d calculation of the 3-d component separating the two environments being considered; 𝑈𝑈� the thermal transmittance of the 1-d component i separating the two environments being considered; 𝐴𝐴� the area over which the value 𝑈𝑈� applies; ψ� linear thermal transmittance; 𝑙𝑙� the length over which the value ψ�applies; 𝑁𝑁� the number of 2-d components; 𝑁𝑁� the number of 1-d components. the standard en iso 10211 (2017) explains modelling conditions and calculation method of the heat transmission coefficients. so using 3-d simulation software heat3, which is validated against the standard en iso 10211 (2017), the model of envelope fragments was created. the model was 600 mm wide and 600 mm high with one "l" shape heat-conductive connection in the middle. the model was split into finite elements. maximum numerical cells 𝑁𝑁� � �� were applied in xdirection, y-direction and z-direction. then boundary conditions were attributed to the internal surface and the external surface of the wall fragments. according to the en 6946 (2017) thermal resistance of internal surface is 0.13 (m²∙k)/w and the same thermal resistance value 0.13 (m²∙k)/w of surface located in front of the ventilated air gap. temperature difference through the fragment was 1 k. after calculations, the heat flow through the envelope fragment was obtained and using that value the heat transfer coefficient u was calculated. the standard en iso 6946 (2017) provides an approximate method that can be used for elements containing inhomogeneous layers, including the effect of metal connectors, by means of a correction term (en iso 6946 2017). the correction to the thermal transmittance is given by: ∆𝑈𝑈� � � ∙ ��∙��∙���� ∙ � �� ���� �� (6) where: � � ��� if fastener fully penetrates the insulation layer; � � ��� � ���� in the case of recessed fastener; 𝜆𝜆� thermal conductivity of the fastener (w/(mꞏk)); 𝑛𝑛� the number of fasteners per m²; 𝐴𝐴� the cross-sectional area of one fastener (m²); 𝑑𝑑� the thickness of the insulation layer containing the fastener (m); 𝑑𝑑� the length of the fastener that penetrates the insulation layer (m); 𝑅𝑅� the thermal resistance of the insulation layer penetrated by the fasteners (m²ꞏk/w); 𝑅𝑅��� the total thermal resistance of the component ignoring any thermal bridging. the calculation method according to en 6946 (2017) does not estimate the influence of steel screw fastening the "l" shape connection to the load bearing wall layer. for calculation of the heat transfer coefficient of envelope fragment, according to this method, the total resistance of all fragment layers is calculated and the correction of the thermal transmittance according to eq.6 is added. 2.2. parameters of elements of wall fragments for empirical calculation and numerical simulation since the thickness and conductivity of thermal insulation are some of the most significant parameters for value of point thermal transmittance, this calculation is carried out in accordance with two methodologies by changing these parameters. the ventilated facade systems with four different thermal conductivity connections were chosen for the calculations (fig.4.). the conductivity of glass fiber reinforced plastic connectors is 0.23 w/(mꞏk), stainless steel connectors  17 w/(mꞏk), zinc coated steel connectors  50 w/(mꞏk), and aluminium alloy connectors  160 w/(mꞏk). “l” shape connectors were chosen, because that shape is commonly used in practice. the thickness of all kind of these connectors was 3 mm, width − 100 mm, a part connected to wall − 50 mm. total length of the connector through the insulation layer was in accordance with the thickness of the thermal insulation layer. there were used 2.78 pcs of connectors per 1m² in calculations. also four thicknesses of thermal insulation were used: 200 mm, 300 mm, 330 mm and 400 mm. two types of thermal insulation materials were chosen with different thermal conductivity: 0.036 w/(mꞏk) and 0.040 w/(mꞏk). the load bearing wall was the same in all cases. the thermal conductivity of load bearing wall was 0.7 w/(mꞏk) like ceramic brick masonry and the thickness of this wall was 250 mm. finishing layer on the inner side of the envelope was 15 mm thick plaster with thermal conductivity 0.882 w/(mꞏk). all other fastening elements like screws in the ventilated facade system were steel elements (λ=50 w/(mꞏk)). they were simulated as square cross section elements (7 mm x 7 mm), whereas only square elements could be drawing in heat3 software. all of calculations were performed in two cases. the first of them was with thermal break between load bearing wall and connectors, and the second one without thermal break. thermal conductivity of that break was 0.17 w/(mꞏk). dimensions of thermal break are the same like base of "l" shape connections (50 mm x 100 mm) with 5 mm thickness. (5) where: l3d − the thermal coupling coefficient obtained from 3-d calculation of the 3-d component separating the two environments being considered; ui – the thermal transmittance of the 1-d component i separating the two environments being considered; ai − the area over which the value ui applies; ψj − linear thermal transmittance; lj the length over which the value ψj applies; nj – the number of 2-d components; ni – the number of 1-d components. the standard en iso 10211 (2017) explains modelling conditions and calculation method of the heat transmission coefficients. so using 3-d simulation software heat3, which is validated against the standard en iso 10211 (2017), the model of envelope fragments was created. the model was 600 mm wide and 600 mm high with one “l” shape heat-conductive connection in the middle. the model was split into finite elements. maximum numerical cells ni = 45 were applied in x-direction, y-direction and z-direction. then boundary conditions were attributed to the internal surface and the external surface of the wall fragments. according to the en 6946 (2017) thermal resistance of internal surface is 0.13 (m²∙k)/w and the same thermal resistance value 0.13 (m²∙k)/w of surface located in front of the ventilated air gap. temperature difference through the fragment was 1 k. after calculations, the heat flow through the envelope fragment was obtained and using that value the heat transfer coefficient u was calculated. the standard en iso 6946 (2017) provides an approximate method that can be used for elements containing inhomogeneous layers, including the effect of metal connectors, by means of a correction term (en iso 6946 2017). the correction to the thermal transmittance is given by: with a homogenous thermal conductivity. the effect of mechanical fasteners can be assessed by calculations in accordance with en iso 10211 (2017) in order to obtain the point thermal transmittance, χ, due to one fastener calculated according to en iso 6946. the correction to the thermal transmittance is given by: ∆𝑈𝑈� � 𝑛𝑛� ∙ 𝜒𝜒 (4) where: 𝑛𝑛� the number of fasteners per m². 𝜒𝜒 ��the point thermal transmittance, are determined by: 𝜒𝜒 � 𝐿𝐿�� � ∑ 𝑈𝑈� ∙ 𝐴𝐴������ � ∑ ψ� ∙ 𝑙𝑙� �� ��� ; (5) where: 𝐿𝐿�� the thermal coupling coefficient obtained from 3-d calculation of the 3-d component separating the two environments being considered; 𝑈𝑈� the thermal transmittance of the 1-d component i separating the two environments being considered; 𝐴𝐴� the area over which the value 𝑈𝑈� applies; ψ� linear thermal transmittance; 𝑙𝑙� the length over which the value ψ�applies; 𝑁𝑁� the number of 2-d components; 𝑁𝑁� the number of 1-d components. the standard en iso 10211 (2017) explains modelling conditions and calculation method of the heat transmission coefficients. so using 3-d simulation software heat3, which is validated against the standard en iso 10211 (2017), the model of envelope fragments was created. the model was 600 mm wide and 600 mm high with one "l" shape heat-conductive connection in the middle. the model was split into finite elements. maximum numerical cells 𝑁𝑁� � �� were applied in xdirection, y-direction and z-direction. then boundary conditions were attributed to the internal surface and the external surface of the wall fragments. according to the en 6946 (2017) thermal resistance of internal surface is 0.13 (m²∙k)/w and the same thermal resistance value 0.13 (m²∙k)/w of surface located in front of the ventilated air gap. temperature difference through the fragment was 1 k. after calculations, the heat flow through the envelope fragment was obtained and using that value the heat transfer coefficient u was calculated. the standard en iso 6946 (2017) provides an approximate method that can be used for elements containing inhomogeneous layers, including the effect of metal connectors, by means of a correction term (en iso 6946 2017). the correction to the thermal transmittance is given by: ∆𝑈𝑈� � � ∙ ��∙��∙���� ∙ � �� ���� �� (6) where: � � ��� if fastener fully penetrates the insulation layer; � � ��� � ���� in the case of recessed fastener; 𝜆𝜆� thermal conductivity of the fastener (w/(mꞏk)); 𝑛𝑛� the number of fasteners per m²; 𝐴𝐴� the cross-sectional area of one fastener (m²); 𝑑𝑑� the thickness of the insulation layer containing the fastener (m); 𝑑𝑑� the length of the fastener that penetrates the insulation layer (m); 𝑅𝑅� the thermal resistance of the insulation layer penetrated by the fasteners (m²ꞏk/w); 𝑅𝑅��� the total thermal resistance of the component ignoring any thermal bridging. the calculation method according to en 6946 (2017) does not estimate the influence of steel screw fastening the "l" shape connection to the load bearing wall layer. for calculation of the heat transfer coefficient of envelope fragment, according to this method, the total resistance of all fragment layers is calculated and the correction of the thermal transmittance according to eq.6 is added. 2.2. parameters of elements of wall fragments for empirical calculation and numerical simulation since the thickness and conductivity of thermal insulation are some of the most significant parameters for value of point thermal transmittance, this calculation is carried out in accordance with two methodologies by changing these parameters. the ventilated facade systems with four different thermal conductivity connections were chosen for the calculations (fig.4.). the conductivity of glass fiber reinforced plastic connectors is 0.23 w/(mꞏk), stainless steel connectors  17 w/(mꞏk), zinc coated steel connectors  50 w/(mꞏk), and aluminium alloy connectors  160 w/(mꞏk). “l” shape connectors were chosen, because that shape is commonly used in practice. the thickness of all kind of these connectors was 3 mm, width − 100 mm, a part connected to wall − 50 mm. total length of the connector through the insulation layer was in accordance with the thickness of the thermal insulation layer. there were used 2.78 pcs of connectors per 1m² in calculations. also four thicknesses of thermal insulation were used: 200 mm, 300 mm, 330 mm and 400 mm. two types of thermal insulation materials were chosen with different thermal conductivity: 0.036 w/(mꞏk) and 0.040 w/(mꞏk). the load bearing wall was the same in all cases. the thermal conductivity of load bearing wall was 0.7 w/(mꞏk) like ceramic brick masonry and the thickness of this wall was 250 mm. finishing layer on the inner side of the envelope was 15 mm thick plaster with thermal conductivity 0.882 w/(mꞏk). all other fastening elements like screws in the ventilated facade system were steel elements (λ=50 w/(mꞏk)). they were simulated as square cross section elements (7 mm x 7 mm), whereas only square elements could be drawing in heat3 software. all of calculations were performed in two cases. the first of them was with thermal break between load bearing wall and connectors, and the second one without thermal break. thermal conductivity of that break was 0.17 w/(mꞏk). dimensions of thermal break are the same like base of "l" shape connections (50 mm x 100 mm) with 5 mm thickness. (6) where: α = 0.8 if fastener fully penetrates the insulation layer; with a homogenous thermal conductivity. the effect of mechanical fasteners can be assessed by calculations in accordance with en iso 10211 (2017) in order to obtain the point thermal transmittance, χ, due to one fastener calculated according to en iso 6946. the correction to the thermal transmittance is given by: ∆𝑈𝑈� � 𝑛𝑛� ∙ 𝜒𝜒 (4) where: 𝑛𝑛� the number of fasteners per m². 𝜒𝜒 ��the point thermal transmittance, are determined by: 𝜒𝜒 � 𝐿𝐿�� � ∑ 𝑈𝑈� ∙ 𝐴𝐴������ � ∑ ψ� ∙ 𝑙𝑙� �� ��� ; (5) where: 𝐿𝐿�� the thermal coupling coefficient obtained from 3-d calculation of the 3-d component separating the two environments being considered; 𝑈𝑈� the thermal transmittance of the 1-d component i separating the two environments being considered; 𝐴𝐴� the area over which the value 𝑈𝑈� applies; ψ� linear thermal transmittance; 𝑙𝑙� the length over which the value ψ�applies; 𝑁𝑁� the number of 2-d components; 𝑁𝑁� the number of 1-d components. the standard en iso 10211 (2017) explains modelling conditions and calculation method of the heat transmission coefficients. so using 3-d simulation software heat3, which is validated against the standard en iso 10211 (2017), the model of envelope fragments was created. the model was 600 mm wide and 600 mm high with one "l" shape heat-conductive connection in the middle. the model was split into finite elements. maximum numerical cells 𝑁𝑁� � �� were applied in xdirection, y-direction and z-direction. then boundary conditions were attributed to the internal surface and the external surface of the wall fragments. according to the en 6946 (2017) thermal resistance of internal surface is 0.13 (m²∙k)/w and the same thermal resistance value 0.13 (m²∙k)/w of surface located in front of the ventilated air gap. temperature difference through the fragment was 1 k. after calculations, the heat flow through the envelope fragment was obtained and using that value the heat transfer coefficient u was calculated. the standard en iso 6946 (2017) provides an approximate method that can be used for elements containing inhomogeneous layers, including the effect of metal connectors, by means of a correction term (en iso 6946 2017). the correction to the thermal transmittance is given by: ∆𝑈𝑈� � � ∙ ��∙��∙���� ∙ � �� ���� �� (6) where: � � ��� if fastener fully penetrates the insulation layer; � � ��� � ���� in the case of recessed fastener; 𝜆𝜆� thermal conductivity of the fastener (w/(mꞏk)); 𝑛𝑛� the number of fasteners per m²; 𝐴𝐴� the cross-sectional area of one fastener (m²); 𝑑𝑑� the thickness of the insulation layer containing the fastener (m); 𝑑𝑑� the length of the fastener that penetrates the insulation layer (m); 𝑅𝑅� the thermal resistance of the insulation layer penetrated by the fasteners (m²ꞏk/w); 𝑅𝑅��� the total thermal resistance of the component ignoring any thermal bridging. the calculation method according to en 6946 (2017) does not estimate the influence of steel screw fastening the "l" shape connection to the load bearing wall layer. for calculation of the heat transfer coefficient of envelope fragment, according to this method, the total resistance of all fragment layers is calculated and the correction of the thermal transmittance according to eq.6 is added. 2.2. parameters of elements of wall fragments for empirical calculation and numerical simulation since the thickness and conductivity of thermal insulation are some of the most significant parameters for value of point thermal transmittance, this calculation is carried out in accordance with two methodologies by changing these parameters. the ventilated facade systems with four different thermal conductivity connections were chosen for the calculations (fig.4.). the conductivity of glass fiber reinforced plastic connectors is 0.23 w/(mꞏk), stainless steel connectors  17 w/(mꞏk), zinc coated steel connectors  50 w/(mꞏk), and aluminium alloy connectors  160 w/(mꞏk). “l” shape connectors were chosen, because that shape is commonly used in practice. the thickness of all kind of these connectors was 3 mm, width − 100 mm, a part connected to wall − 50 mm. total length of the connector through the insulation layer was in accordance with the thickness of the thermal insulation layer. there were used 2.78 pcs of connectors per 1m² in calculations. also four thicknesses of thermal insulation were used: 200 mm, 300 mm, 330 mm and 400 mm. two types of thermal insulation materials were chosen with different thermal conductivity: 0.036 w/(mꞏk) and 0.040 w/(mꞏk). the load bearing wall was the same in all cases. the thermal conductivity of load bearing wall was 0.7 w/(mꞏk) like ceramic brick masonry and the thickness of this wall was 250 mm. finishing layer on the inner side of the envelope was 15 mm thick plaster with thermal conductivity 0.882 w/(mꞏk). all other fastening elements like screws in the ventilated facade system were steel elements (λ=50 w/(mꞏk)). they were simulated as square cross section elements (7 mm x 7 mm), whereas only square elements could be drawing in heat3 software. all of calculations were performed in two cases. the first of them was with thermal break between load bearing wall and connectors, and the second one without thermal break. thermal conductivity of that break was 0.17 w/(mꞏk). dimensions of thermal break are the same like base of "l" shape connections (50 mm x 100 mm) with 5 mm thickness. in the case of recessed fastener; λf – thermal conductivity of the fastener (w/(m∙k)); nf – the number of fasteners per m²; af – the cross-sectional area of one fastener (m²); d0 – the thickness of the insulation layer containing the fastener (m); d1 – the length of the fastener that penetrates the insulation layer (m); r1 the thermal resistance of the insulation layer penetrated by the fasteners (m²∙k/w); rtot – the total thermal resistance of the component ignoring any thermal bridging.. the calculation method according to en 6946 (2017) does not estimate the influence of steel screw fastening the “l” shape connection to the load bearing wall layer. for calculation of the heat transfer coefficient of envelope fragment, according to this method, the total resistance of all fragment layers is calculated and the correction of the thermal transmittance according to eq.6 is added. parameters of elements of wall fragments for empirical calculation and numerical simulation since the thickness and conductivity of thermal insulation are some of the most significant parameters for value of point thermal transmittance, this calculation is carried out in accordance with two methodologies by changing these parameters. the ventilated facade systems with four different thermal conductivity connections were chosen for the calculations (fig.4.). the conductivity of glass fiber reinforced plastic connectors is 0.23 w/(m∙k), stainless steel connectors − 17 w/(m∙k), zinc coated steel connectors − 50 w/(m∙k), and aluminium alloy connectors − 160 w/(m∙k). “l” shape connectors were chosen, because that shape is commonly used in practice. the thickness of all kind of these connectors was 3 mm, width − 100 mm, a part connected to wall − 50 mm. total length of the connector through the insulation layer was in accordance with the thickness of the thermal insulation layer. there were used 2.78 pcs of connectors per 1m² in calculations. also four thicknesses of thermal insulation were used: 200 mm, 300 mm, 330 mm and 400 mm. two journal of sustainable architecture and civil engineering 2018/2/23 44 types of thermal insulation materials were chosen with different thermal conductivity: 0.036 w/ (m∙k) and 0.040 w/(m∙k). the load bearing wall was the same in all cases. the thermal conductivity of load bearing wall was 0.7 w/(m∙k) like ceramic brick masonry and the thickness of this wall was 250 mm. finishing layer on the inner side of the envelope was 15 mm thick plaster with thermal conductivity 0.882 w/(m∙k). all other fastening elements like screws in the ventilated facade system were steel elements (λ=50 w/(m∙k)). they were simulated as square cross section elements (7 mm x 7 mm), whereas only square elements could be drawing in heat3 software. all of calculations were performed in two cases. the first of them was with thermal break between load bearing wall and connectors, and the second one without thermal break. thermal conductivity of that break was 0.17 w/(m∙k). dimensions of thermal break are the same like base of “l” shape connections (50 mm x 100 mm) with 5 mm thickness. fig. 4 fragment of ventilated facade system: a) side view; b) top view; c) 3d model a) b) c) fig. 4.fragment of ventilated facade system: a) side view; b) top view; c) 3d model 3. results 3.1. the influence of thermal break the use of the thermal break between the load bearing wall and the heat-conductive connections is a quite good way to reduce heat flows through the envelope. using the glass fiber reinforced plastic connections the difference in results of 3d with thermal break and without them is almost equal to zero (0.0−0.3 %), using the stainless steel connections that difference is up to 0.9 % and steel connections  up to 5.5 %. difference in results of 3-d calculations of ventilated facade system fragments with different thermal conductivity insulation and aluminium alloy connections with thermal break and without them varies from 4.8 % to 5.7 %. the biggest difference in the results is obtained with the highest heat conductivity connectors − aluminium alloy fasteners: using the thermal break, u=0.195 w/(m²∙k), without the thermal break u=0.207 w/(m²∙k). according to the en 6946 (2017) method the influence of the thermal break could not be evaluated, consequently only numerical calculations can be compared. 3.2. the influence of thickness of thermal insulation according to the empirical and numerical calculations of ventilated facade system with thermal insulating material of λ=0.036 w/mꞏk, the heat transfer coefficient when used aluminium alloy connections is very high compared to the calculation results using other kinds of connectors (table 1.): the heat transfer coefficient u=0.592 w/(m²∙k) with thickness of thermal insulation 200 mm and u=0.324 w/(m²∙k) with 400 mm. the heat transfer coefficient of envelope fragments with the stainless steel connections respectively − u=0.207 w/(m²∙k) and u=0.111 w/(m²∙k) and for fragments with the glass fiber reinforced plastic connections − u=0.162 w/(m²∙k) and u=0.086 w/(m²∙k) respectively. the calculation results showed the influence of different connectors on heat transfer coefficient of ventilated facade system increases when thickness of thermal insulating material is bigger. the increment of heat transfer of ventilated wall depending on thickness of thermal insulation layer and type of connectors, compared to wall without connectors is presented in fig. 5. the results show the negative trend: the influence of heat conductive connectors increases with increment of thickness of thermal insulating layer. table 1.the empirical calculations results of the heat transfer coefficient with different thickness of thermal insulation thermal insulation heat transfer u, w/(m²ꞏk) thermal conductivity λ, w/(mꞏk) thickness, mm heat-conductive connections glass fiber stainless steel steel aluminium alloy 0.036 200 0.162 0.207 0.296 0.592 400 0.086 0.111 0.160 0.324 0.040 200 0.178 0.222 0.309 0.598 400 0.094 0.119 0.168 0.330 a) b) c) the influence of thermal break the use of the thermal break between the load bearing wall and the heat-conductive connections is a quite good way to reduce heat flows through the envelope. using the glass fiber reinforced plastic connections the difference in results of 3-d with thermal break and without them is almost equal to zero (0.0−0.3 %), using the stainless steel connections that difference is up to 0.9 % and steel connections − up to 5.5 %. difference in results of 3-d calculations of ventilated facade system fragments with different thermal conductivity insulation and aluminium alloy connections with thermal break and without them varies from 4.8 % to 5.7 %. the biggest difference in the results is obtained with the highest heat conductivity connectors − aluminium alloy fasteners: using the thermal break, u=0.195 w/(m²∙k), without the thermal break u=0.207 w/(m²∙k). according to the en 6946 (2017) method the influence of the thermal break could not be evaluated, consequently only numerical calculations can be compared. the influence of thickness of thermal insulation according to the empirical and numerical calculations of ventilated facade system with thermal insulating material of λ=0.036 w/m∙k, the heat transfer coefficient when used aluminium alloy connections is very high compared to the calculation results using other kinds of connectors (table 1): the heat transfer coefficient u=0.592 w/(m²∙k) with thickness of thermal insulation 200 mm and u=0.324 w/ (m²∙k) with 400 mm. the heat transfer coefficient of envelope fragments with the stainless steel connections respectively − u=0.207 w/(m²∙k) and u=0.111 w/(m²∙k) and for fragments with the glass fiber reinforced plastic connections − u=0.162 w/(m²∙k) and u=0.086 w/(m²∙k) respectively. the calculation results showed the influence of different connectors on heat transfer coefficient of ventilated facade system increases when thickness of thermal insulating material is bigger. the increment of heat transfer of ventilated wall depending on thickness of thermal insulation layer and type of connectors, compared to wall without connectors is presented in fig. 5. the results show the negative trend: the influence of heat conductive connectors increases with increment of thickness of thermal insulating layer. results 45 journal of sustainable architecture and civil engineering 2018/2/23 table 1 the empirical calculations results of the heat transfer coefficient with different thickness of thermal insulation thermal insulation heat transfer u, w/(m²·k) thermal conductivity λ, w/(m·k) thickness, mm heat-conductive connections glass fiber stainless steel steel aluminium alloy 0.036 200 0.162 0.207 0.296 0.592 400 0.086 0.111 0.160 0.324 0.040 200 0.178 0.222 0.309 0.598 400 0.094 0.119 0.168 0.330 the impact of heat conductivity of thermal insulation the heat conductivity of the thermal insulation is one of the most significant factors to the heat transfer coefficient of envelope. calculations results of the heat transfer through ventilated facade system without thermal breaks with 300 mm of thermal insulating material and with heat conductivity 0.036 w/(m∙k) and 0.040 w/(m∙k) are shown in table 2. for glass fiber connections, the fig. 5 the influence of the thermal bridges on thermal transmittance of ventilated facade system fig. 5. the influence of the thermal bridges on thermal transmittance of ventilated facade system 3.3. the impact of heat conductivity of thermal insulation the heat conductivity of the thermal insulation is one of the most significant factors to the heat transfer coefficient of envelope. calculations results of the heat transfer through ventilated facade system without thermal breaks with 300 mm of thermal insulating material and with heat conductivity 0.036 w/(mꞏk) and 0.040 w/(mꞏk) are shown in table 2. for glass fiber connections, the difference between heat transfer coefficients with different conductivity thermal insulation is about 10 %, it means, reduction of u value is only due to difference of conductivity of thermal insulation material. for stainless steel and steel connectors, this difference is about 8 %, it shows, that the impact of heat conductive connectors relatively increases in more insulated layers. for aluminium alloy connectors, significant differences in calculation results using different methods occur. then using 3-d simulation, this difference is about 5 %, then empirical calculation – about 10 %. these differences show that 3-d simulation is more reliable because follow the trends of distribution of calculation results of other cases (more significant impact). table 2.the calculations results of the heat transfer coefficient with different heat conductivity thermal insulation thermal insulation heat-conductive connections heat transfer u, w/(m²ꞏk) thickness, mm thermal conductivity λ, w/(mꞏk) material thermal conductivity λc, w/(mꞏk) 3d simulating (en 10211) empirical calculations (en 6946) 300 0.036 glassfiber 0.23 0.112 0.112 stainless steel 17 0.143 0.144 steel 50 0.177 0.208 aluminium alloy 160 0.217 0.419 0.040 glassfiber 0.23 0.124 0.123 stainless steel 17 0.154 0.155 steel 50 0.194 0.217 aluminium alloy 160 0.228 0.425 3.4. different heat conductive connections it is obvious that using higher thermal conductivity connectors, the values of point thermal bridges (calculated using 3-d method), also increase as the heat transfer coefficient of the envelope (table 3. and fig.6.). the heat transfer coefficient of the fragment with thermal break decreased 46.4% − 89.9% using different heat conductivity connections when the thickness of thermal insulation was 200 mm and 400 mm. the biggest difference (89.9%) was obtained with glass fiber connections, which have the lowest thermal conductivity. the smallest change in the heat transfer (46.4%) was obtained with the highest thermal conductivity connections − aluminium alloy. 0 50 100 150 200 250 300 150 200 250 300 350 400 450 th e  in flu en ce  o f t he rm al  b rid ge s   o n  u ‐v al ue s,  % thickness of thermal insulation, mm glassfiber (3d simulating) glassfiber (empirical calc.) stainless steel (3d simulating) stainless steel (empirical calc.) steel (3d simulating) steel (empirical calc.) aluminium alloy (3d simulating) aluminium alloy (empirical calc.) table 2 the calculations results of the heat transfer coefficient with different heat conductivity thermal insulation thermal insulation heat-conductive connections heat transfer u, w/(m²·k) thickness, mm thermal conductivity λ, w/ (m·k) material thermal conductivity λc, w/(m·k) 3d simulating (en 10211) empirical calculations (en 6946) 300 0.036 glassfiber 0.23 0.112 0.112 stainless steel 17 0.143 0.144 steel 50 0.177 0.208 aluminium alloy 160 0.217 0.419 0.040 glassfiber 0.23 0.124 0.123 stainless steel 17 0.154 0.155 steel 50 0.194 0.217 aluminium alloy 160 0.228 0.425 journal of sustainable architecture and civil engineering 2018/2/23 46 difference between heat transfer coefficients with different conductivity thermal insulation is about 10 %, it means, reduction of u value is only due to difference of conductivity of thermal insulation material. for stainless steel and steel connectors, this difference is about 8 %, it shows, that the impact of heat conductive connectors relatively increases in more insulated layers. for aluminium alloy connectors, significant differences in calculation results using different methods occur. then using 3-d simulation, this difference is about 5 %, then empirical calculation – about 10 %. these differences show that 3-d simulation is more reliable because follow the trends of distribution of calculation results of other cases (more significant impact). thermal insulation heat-conductive connections heat transfer u, w/(m²·k) thickness, mm thermal conductivity λ, w/(m·k) material thermal conductivity λc, w/(m·k) with thermal break without thermal break 200 0.036 glassfiber 0.23 0.163 0.163 stainless steel 17 0.200 0.202 steel 50 0.229 0.243 aluminum alloy 160 0.257 0.272 400 glassfiber 0.23 0.086 0.086 stainless steel 17 0.111 0.111 steel 50 0.139 0.142 aluminum alloy 160 0.176 0.185 table 3 the 3-d calculations results of the heat transfer coefficient with different heat conductivity connections different heat conductive connections it is obvious that using higher thermal conductivity connectors, the values of point thermal bridges (calculated using 3-d method), also increase as the heat transfer coefficient of the envelope (table 3 and fig.6). the heat transfer coefficient of the fragment with thermal break decreased 46.4% − 89.9% using different heat conductivity connections when the thickness of thermal insulation was 200 mm and 400 mm. the biggest difference (89.9%) was obtained with glass fiber connections, which have the lowest thermal conductivity. the smallest change in the heat transfer (46.4%) was obtained with the highest thermal conductivity connections − aluminium alloy. fig. 6 the effect of the heat conductivity of connections on heat transfer coefficient of ventilated facade system (3-d method) table 3.the 3-d calculations results of the heat transfer coefficient with different heat conductivity connections thermal insulation heat-conductive connections heat transfer u, w/(m²ꞏk) thickness, mm thermal conductivity λ, w/(mꞏk) material thermal conductivity λc, w/(mꞏk) with thermal break without thermal break 200 0.036 glassfiber 0.23 0.163 0.163 stainless steel 17 0.200 0.202 steel 50 0.229 0.243 aluminum alloy 160 0.257 0.272 400 glassfiber 0.23 0.086 0.086 stainless steel 17 0.111 0.111 steel 50 0.139 0.142 aluminum alloy 160 0.176 0.185 fig. 6. the effect of the heat conductivity of connections on heat transfer coefficient of ventilated facade system (3-d method) moreover, the strangest differences in results were observed between two used calculation methods with the same connectors (fig.7.). for example, using less heat-conductive connections such as stainless steel the value of the heat transfer coefficient calculated by two methods varied by 3.6% . that difference is small enough to think, that both calculation methods are suitable for the calculation of the heat transfer through the ventilated facade system with heat-conductive connections. however, very big differences were determinated comparing the results when aluminium alloy connections were used. these differences ranged from 70.0 % up to 130.4 %. in all cases the empirical calculation method according to en 6946 (2017) showed much higher values of heat transfer compared to the method according en 10211 (2017) using 3-d simulation software. 0,0500 0,1000 0,1500 0,2000 0,2500 0,3000 0 50 100 150 200 h ea t t ra ns fe r c oe ff ic ie nt  u , w /( m ²∙k ) heat conductivity of connections λc, w/(m∙k) with thermal break (thermal insulation 200 mm) without thermal break (thermal insulation 200 mm) with thermal break (thermal insulation 400 mm) witout thermal break (thermal insulation 400 mm) 47 journal of sustainable architecture and civil engineering 2018/2/23 moreover, the strangest differences in results were observed between two used calculation methods with the same connectors (fig.7.). for example, using less heat-conductive connections such as stainless steel the value of the heat transfer coefficient calculated by two methods varied by 3.6%. that difference is small enough to think, that both calculation methods are suitable for the calculation of the heat fig. 7 minimum and maximum percentage of difference in calculation results using two calculation methods fig. 7. minimum and maximum percentage of difference in calculation results using two calculation methods 4. conclusions the results of performed investigations shows, that incorrect evaluating of thermal bridges or ignoring the effect of the metal elements in building thermal insulated constructions could be the reason of reduction of thermal resistance of buildings envelopes up to 30 % with lower heat conductivity metal elements and up to 2.8 times with very high heat conductivity metal elements. consequently, the impact of heat-conductive connections on heat transfer coefficient of envelope must be evaluated in ventilated facade systems. the calculation results also indicated: the influence of thermal breaks is significant only for insulation systems with steel and aluminium alloys connectors; the influence of heat conductive connectors increases with increment of thickness of thermal insulating layer. the higher influence of thermal conductive connectors was determined when lower-conductive thermo-insulating materials are used; the thermal transmittance of ventilated facade system increases up to 2 times when the aluminium connections are used, so they should not be used for low energy buildings; the difference between heat transfer coefficients with different conductivity of thermal insulation show that 3-d simulation is more reliable method for evaluation of point thermal bridges because obtained results follow the trends of distribution of calculation results; significant difference in results of the empirical and 3-d calculation method (the calculations with aluminium alloy connections gave even 130 % difference) require to corrected empirical method at least for calculation of the heat transfer through the building envelopes with high thermal conductivity connections such as aluminium alloy connectors. whereas, the reason was not clarified why the calculation results using two methods are so markedly different, the experimental research is going to be carried out using a guarded hot box method. references al-sanea s.a., zedan m.f. effect of thermal bridges on transmission loads and thermal resistance of building walls under dynamic conditions. applied energy, 2012; 584-593. https://doi.org/10.1016/j.apenergy.2012.04.038 cappelletti f., gasparella a., romagnoni p., baggio p. analysis of the influence of installation thermal bridges on windows performance: the case of clay block walls. energy and buildings, 2011; 1435-1442. european commission. proposal for a recast of the energy performance of buildings directive (2002-91-ec). sec (2008) 2865, brussels; 2008. ‐140,000 ‐120,000 ‐100,000 ‐80,000 ‐60,000 ‐40,000 ‐20,000 0,000 d iff er en ce  o f r es ul ts  in  a cc or da nc e  w ith  tw o  m et ho ds  o f c al cu la tio n,  % glasfiber min glassfiber max stainless steel min stainless steel max steel min steel max aluminium alloy min aluminium alloy max transfer through the ventilated facade system with heat-conductive connections. however, very big differences were determinated comparing the results when aluminium alloy connections were used. these differences ranged from 70.0 % up to 130.4 %. in all cases the empirical calculation method according to en 6946 (2017) showed much higher values of heat transfer compared to the method according en 10211 (2017) using 3-d simulation software. conclusions the results of performed investigations shows, that incorrect evaluating of thermal bridges or ignoring the effect of the metal elements in building thermal insulated constructions could be the reason of reduction of thermal resistance of buildings envelopes up to 30 % with lower heat conductivity metal elements and up to 2.8 times with very high heat conductivity metal elements. consequently, the impact of heat-conductive connections on heat transfer coefficient of envelope must be evaluated in ventilated facade systems. the calculation results also indicated: _ the influence of thermal breaks is significant only for insulation systems with steel and aluminium alloys connectors; _ the influence of heat conductive connectors increases with increment of thickness of thermal insulating layer. _ the higher influence of thermal conductive connectors was determined when lower-conductive thermo-insulating materials are used; _ the thermal transmittance of ventilated facade system increases up to 2 times when the aluminium connections are used, so they should not be used for low energy buildings; _ the difference between heat transfer coefficients with different conductivity of thermal insulation show that 3-d simulation is more reliable method for evaluation of point thermal bridges because obtained results follow the trends of distribution of calculation results; _ significant difference in results of the empirical and 3-d calculation method (the calculations with aluminium alloy connections gave even 130 % difference) require to corrected empirical method at least for calculation of the heat transfer through the building envelopes with high thermal conductivity connections such as aluminium alloy connectors. whereas, the reason was not clarified why the calculation results using two methods are so markedly different, the experimental research is going to be carried out using a guarded hot box method. journal of sustainable architecture and civil engineering 2018/2/23 48 al-sanea s.a., zedan m.f. effect of thermal bridges on transmission loads and thermal resistance of building walls under dynamic conditions. applied energy, 2012; 584-593. https://doi.org/10.1016/j.apenergy.2012.04.038 cappelletti f., gasparella a., romagnoni p., baggio p. analysis of the influence of installation thermal bridges on windows performance: the case of clay block walls. energy and buildings, 2011; 1435-1442. european commission. proposal for a recast of the energy performance of buildings directive (2002-91ec). sec (2008) 2865, brussels; 2008. european committee for standardization, en iso 10211, thermal bridges in building construction heat flows and surface temperatures detailed calculations, european committee for standardization, 2017. european committee for standardization, en iso 6946. building components and building elements thermal resistance and thermal transmittance calculation methods, european committee for standardization, 2017. ge h., mcclung v.r, zhang s. impact of balcony thermal bridges on the overall thermal performance of multi-unit residential buildings: a case study. energy and buildings, 2013; 163-173. gorgolewski m. developing a simplified method of calculating u-values in light steel framing. building and environment 2007; 230–236. https://doi. org/10.1016/j.buildenv.2006.07.001 ilomets s. et al. impact of linear thermal bridges on thermal transmittance of renovated apartment buildings. journal of civil engineering and management, 2016; 96-104. https://doi.org/10.3846/13923730.2014.976259 levinskytė a., banionis k., geležiūnas v. the influence of thermal bridges for buildings energy consumption of “a” energy efficiency class. journal of sustainable architecture and civil engineering, 2016; 47-58. methods and instructions for installing ventilated facade cladding (http://www.plantas.lt/file/repository/ ak_lt(plantas).pdf) (accessed 26 june 2018). misiopecki c., bouquin m., gustavsen a., jelle b.p. thermal modelling and investigation of the most energy-efficient window position. energy and buildings, 2018; 1079-1086. quinten j., feldheim v. dynamic modelling of multidimensional thermal bridges in building envelopes: review of existing methods, application and new mixed method. energy and buildings, 2016; 284-293. sadauskiene j. et al. a simplified methodology for evaluating the impact of point thermal bridges on the high-energy performance of a passive house. sustainability, 2015; 16687–16702. https://doi. org/10.3390/su71215840 theodosiou t. et al. thermal bridging analysis on cladding systems for building facades. energy and buildings, 2015; 377-384. theodosiou t., tsikaloudaki k., bikas d. analysis of the thermal bridging effect on ventilated facades. procedia environmental sciences, 2017; 397 – 404. https:// doi.org/10.1016/j.proenv.2017.03.121 zalewski l. et al. experimental and numerical characterization of thermal bridges in prefabricated building walls. energy conversion and management, 2010; 28692877. https://doi.org/10.1016/j.enconman.2010.06.026 raimondas bliūdžius senior researcher laboratory of building physics at the institute of architecture and construction, ktu main research area normalization of heat losses in buildings, thermal insulation of building enclosure, research of the properties of building thermal insulation materials. address tunelio st. 60, lt-44405, kaunas, lithuania tel. +370 687 33708 e-mail: raimondas.bliudzius@ktu.lt references aurelija levinskytė engineer laboratory of building physics at the institute of architecture and construction, ktu phd student institute of architecture and construction, ktu main research area investigation of efficient energy use and assurance of microclimate condition in buildings, heat transfer and thermal insulation address tunelio st. 60, lt-44405 kaunas, lithuania tel. +370 629 40158 e-mail: aurelija.levinskyte@ktu.lt robertas kapačiūnas engineering projects manager technical maintenance group, facilities management, ktu phd student institute of architecture and construction, ktu main research area energy efficiency of buildings address k. donelaičio st. 73, lt44249, kaunas, lithuania tel. + 370 699 30014 e-mail: robertas.kapaciunas@ ktu.lt about the authors mailto:raimondas.bliudzius@ktu.lt mailto:aurelija.levinskyte@ktu.lt mailto:robertas.kapaciunas@ktu.lt mailto:robertas.kapaciunas@ktu.lt 17 journal of sustainable architecture and civil engineering 2019/1/24 corresponding author: ambrose.dodoo@lnu.se lifecycle impacts of structural frame materials for multi-storey building systems received 2018/11/29 accepted after revision 2019/02/07 journal of sustainable architecture and civil engineering vol. 1 / no. 24 / 2019 pp. 17-28 doi 10.5755/j01.sace.24.1.22081 lifecycle impacts of structural frame materials for multistorey building systems jsace 1/24 http://dx.doi.org/10.5755/j01.sace.24.1.22081 ambrose dodoo department of building technology, linnaeus university, växjö, se-35195, sweden in this study the lifecycle primary energy and greenhouse gas (ghg) implications of multi-storey building versions with different structural frame materials as well as construction systems are analysed considering flows from the production, operation and end-of-life phases and the full natural resources chains. the analysed building versions include conventional and modern construction systems with light-frame timber, reinforced concrete-frame, massive timber frame, beam-and-column timber frame or modular timber frame structural systems and are designed to the energy efficiency level of the passive house criteria. the results show that the lifecycle primary energy use and ghg emissions for the reinforced concrete building system are higher than those for the timber-based building systems, due primarily to the lower production primary energy use and ghg emissions as well as greater amount of biomass residues when using wood-based materials. the operation primary energy use and ghg emission for the buildings are lower when heated with cogenerated district heating compared to when heated with electric-based heat pump, showing the significance of heat supply choice. the findings emphasize the importance of structural frame material choice and system-wide lifecycle perspective in reducing primary energy use and ghg emissions in the built environment. keywords: building frame material, concrete, life cycle analysis, passive house, timber. of the global primary energy supply of 576.1 ej in 2016, fossil fuels constituted 81.1%, with oil, coal and fossil gas representing 31.9%, 27.1% and 22.1%, respectively (iea, 2018a). according to the bp’s evolving transition scenario which assumes the global energy system may develop in similar manner as the recent past, global total primary energy use may increase about 35% between 2016 and 2040, with fossil fuels contributing 74% of the total primary energy supply in 2040 (bp, 2018). fossil fuel combustion is a major source of greenhouse gas (ghg) emissions and together with industrial processes linked mainly to cement manufacture accounted for 65% of the global anthropogenic ghg emissions in 2010 (ipcc, 2014). a growing body of evidence indicates that increasing atmospheric concentration of ghgs is altering the global climate system (ipcc, 2014). globally, the building and construction sectors account for 36% of the total final energy use and for about 40% of the total co2 emissions (iea, 2018b). the sectors are suggested to offer significant opportunities to reduce fossil fuels use and thereby shift to a low-carbon built environment (ipcc, 2014). a variety of measures may be deployed to improve energy performance of buildings, including improved thermal envelope insulation and airtightness, high performance windows, efficient technical equipment and supply systems, and use of less energy-intensive building mateintroduction journal of sustainable architecture and civil engineering 2019/1/24 18 rials. lifecycle analysis considering the entire energy and material chains can play an important role in identifying options to reduce energy use and climate impacts of buildings. lifecycle analyses of buildings in cold climates show that the operation phase typically dominates the energetic and climatic impacts while the production phase constitutes a significant share of the impacts for low-energy buildings (cabeza et al., 2014, thormark, 2002). ramesh et al. (2010) reviewed lifecycle analysis studies of 73 conventional and low-energy buildings from 13 countries and noted the production phase to account for 10-20% of the buildings’ total lifecycle energy use. for a low-energy building, thormark (2002) showed that the share of the total lifecycle energy used for production reaches about 45%. the significance of material choice and the role of building systems in reducing overall lifecycle impacts of buildings are discussed and explored in some recent studies (e.g. gustavsson and sathre, 2006, tettey et al., 2014). tettey et al. (2014) found that total production primary energy use is reduced 6-7% while co2 emission is reduced 7-8%, when using an alternative insulation material to achieve the same energy performance for multi-storey buildings. synthesis of research presented by the ipcc (2014) indicates that timber-based building systems results in lower production energy than conventional concrete-based alternatives while concrete-based building systems entail lesser production energy than steel-based alternatives. suzuki et al. (1995) calculated the carbon emissions for construction of wood-frame, lightweight steel-frame and reinforced concrete-frame buildings to be 250, 400 and 850 kg co2/m 2, respectively. studies have analysed lifecycle energy and ghg impacts of buildings considering different activities and flows e.g. (aye et al., 2012, gustavsson et al., 2010, dahlstrøm et al., 2012). aye et al. (2012) considered the production and operation phases in a lifecycle energy and ghg analysis for three australian multi-storey building systems. gustavsson et al. (2010) calculated the primary energy use and co2 emissions of an eight-storey modern wood-frame building, considering the production, operation and end-of-life phases. dahlstrøm et al. (2012) conducted lifecycle assessment of a single-storey residential building designed to the norwegian tek 10 building code or passive house criteria, taking into account the production, operation, maintenance, and end-of-life waste treatment. they found that the passive building results in substantial reduction of primary energy use and ghg emissions compared to the code-compliant building. most studies as above analysed conventional building systems while few studies have explored modern building systems. fewer analyses have compared the lifecycle primary energy use and ghgs emission of conventional and modern building construction systems with different materials, and considering all lifecycle activities. here we investigate lifecycle primary energy use and ghgs emission of multi-storey buildings with different building construction systems for norwegian conditions, considering flows from the production, operation and end-of-life phases of the buildings. the present study explores conventional and modern building systems designed to the norwegian passive house criteria with reinforced concrete or timber structural frame materials. building system versions an existing four-story residential building (fig. 1) with a total heated floor area of 1140 m2 is used as reference to explore the implications of five different building systems. the building has conventional light timber framing structural system comprising studs and joist and foundation made of reinforced concrete. it has elevator besides a stairwell, and contains 16 apartments with living areas ranging from 42 to 78 m2. the façades are made of stucco and wood panelling, and 8 of the apartments have balconies, at the longitudinal ends of the building. a functionally equivalent version of the building is designed using conventional reinforced concrete framing structural system and is documented in persson (1998). for this variant, prefab reinforced concrete replaces the light timber joists floors as well as the load-bearing timber studs and walls while the stucco and wood panelling at the façades are replaced with cement render. 19 journal of sustainable architecture and civil engineering 2019/1/24 besides the conventional light timber-frame and reinforced concrete-frame building versions, additional three modern functionally equivalent timber-frame versions of the reference building are designed with massive timber, beam-and-columns, and prefab modular structural elements, so that five building and construction systems are achieved. the massive timber building system has walls, floors and structural systems as well as load-bearing interior elements constructed with cross laminated timber (clt). for the building with beam-and-column structural system, laminated veneer lumber (lvl) and glulam columns and beams are used as the main structural framework to transfer all horizontal and vertical loads to the foundation. the timber modular system is based on individual volumetric light-frame elements prefabricated off-site and transported to the building site. all five building systems are modelled to fulfil the energy requirements of the norwegian passive house criteria (ns 3700, 2013). table 1 summarizes the thermal characteristics of the buildings while table 2 gives inventory of key construction materials for the finished building systems excluding materials for cabinets, electrical services equipment and heating systems. all the buildings have efficient water taps based on current best available technology (bat) and mechanical ventilation with heat recovery (mvhr) systems, with 82% heat recovery efficiency. for all building systems, the foundations consist of 120-160 mm reinforced concrete slab-on-ground and a 300350 mm layer of expanded polystyrene (eps) insulation laid on 150 mm crushed stones. for the beam-and-columns timber building system, the foundation also includes reinforced concrete footings besides the concrete slab-on-ground to take up concentrated point loads. the configuration of the modular system results in a slightly more floor area compared to the four other systems. otherwise all the five building systems have the same architectural details. fig. 2 presents illustrations of structural elements of the five studied building system versions. reinforced concrete-based elefig. 1 typical floor plan (left) and photograph (right) of the reference, built light-timber frame building ranging from 42 to 78 m2. the façades are made of stucco and wood panelling, and 8 of the apartments have balconies, at the longitudinal ends of the building. figure 1. typical floor plan (left) and photograph (right) of the reference, built light-timber frame building. a functionally equivalent version of the building is designed using conventional reinforced concrete framing structural system and is documented in persson (1998). for this variant, prefab reinforced concrete replaces the light timber joists floors as well as the load-bearing timber studs and walls while the stucco and wood panelling at the façades are replaced with cement render. besides the conventional light timber-frame and reinforced concrete-frame building versions, additional three modern functionally equivalent timber-frame versions of the reference building are designed with massive timber, beam-and-columns, and prefab modular structural elements, so that five building and construction systems are achieved. the massive timber building system has walls, floors and structural systems as well as load-bearing interior elements constructed with cross laminated timber (clt). for the building with beam-and-column structural system, laminated veneer lumber (lvl) and glulam columns and beams are used as the main structural framework to transfer all horizontal and vertical loads to the foundation. the timber modular system is based on individual volumetric light-frame elements prefabricated off-site and transported to the building site. all five building systems are modelled to fulfil the energy requirements of the norwegian passive house criteria (ns 3700, 2013). table 1 summarizes the thermal characteristics of the buildings while table 2 gives inventory of key construction materials for the finished building systems excluding materials for cabinets, electrical services equipment and heating systems. all the buildings have efficient water taps based on current best available technology (bat) and mechanical ventilation with heat recovery (mvhr) systems, with 82% heat recovery efficiency. for all building systems, the foundations consist of 120-160 mm reinforced concrete slab-on-ground and a 300-350 mm layer of expanded polystyrene (eps) insulation laid on 150 mm crushed stones. for the beam-and-columns timber building system, the foundation also includes reinforced concrete footings besides the concrete slab-on-ground to take up concentrated point loads. the configuration of the modular system results in a slightly more floor area compared to the four other systems. otherwise all the five building systems have the same architectural details. figure 2 presents illustrations of structural elements of the five studied building system versions. reinforced concrete-based elevator shaft is used in the beam-andcolumn timber and reinforced concrete building systems while wood-constructed elevator shaft is used ranging from 42 to 78 m2. the façades are made of stucco and wood panelling, and 8 of the apartments have balconies, at the longitudinal ends of the building. figure 1. typical floor plan (left) and photograph (right) of the reference, built light-timber frame building. a functionally equivalent version of the building is designed using conventional reinforced concrete framing structural system and is documented in persson (1998). for this variant, prefab reinforced concrete replaces the light timber joists floors as well as the load-bearing timber studs and walls while the stucco and wood panelling at the façades are replaced with cement render. besides the conventional light timber-frame and reinforced concrete-frame building versions, additional three modern functionally equivalent timber-frame versions of the reference building are designed with massive timber, beam-and-columns, and prefab modular structural elements, so that five building and construction systems are achieved. the massive timber building system has walls, floors and structural systems as well as load-bearing interior elements constructed with cross laminated timber (clt). for the building with beam-and-column structural system, laminated veneer lumber (lvl) and glulam columns and beams are used as the main structural framework to transfer all horizontal and vertical loads to the foundation. the timber modular system is based on individual volumetric light-frame elements prefabricated off-site and transported to the building site. all five building systems are modelled to fulfil the energy requirements of the norwegian passive house criteria (ns 3700, 2013). table 1 summarizes the thermal characteristics of the buildings while table 2 gives inventory of key construction materials for the finished building systems excluding materials for cabinets, electrical services equipment and heating systems. all the buildings have efficient water taps based on current best available technology (bat) and mechanical ventilation with heat recovery (mvhr) systems, with 82% heat recovery efficiency. for all building systems, the foundations consist of 120-160 mm reinforced concrete slab-on-ground and a 300-350 mm layer of expanded polystyrene (eps) insulation laid on 150 mm crushed stones. for the beam-and-columns timber building system, the foundation also includes reinforced concrete footings besides the concrete slab-on-ground to take up concentrated point loads. the configuration of the modular system results in a slightly more floor area compared to the four other systems. otherwise all the five building systems have the same architectural details. figure 2 presents illustrations of structural elements of the five studied building system versions. reinforced concrete-based elevator shaft is used in the beam-andcolumn timber and reinforced concrete building systems while wood-constructed elevator shaft is used table 1 thermal characteristics of the building systems description reinforced concrete frame light-frame timber frame massive timber frame beam & column timber frame modular timber frame u-value (w/m2 k): roof 0.08 0.08 0.08 0.08 0.08 external wall 0.113 0.113 0.104 0.11 0.111 separating wall 0.161 0.161 0.16 0.215 0.196 internal floors 0.135 0.135 0.127 0.13 0.135 windows 0.8 0.8 0.8 0.8 0.8 doors 0.8 0.8 0.8 0.8 0.8 ground floor 0.108 0.108 0.108 0.108 0.108 infiltration (l/s m2 @ 50 pa) 0.3 0.3 0.3 0.3 0.3 journal of sustainable architecture and civil engineering 2019/1/24 20 in the other timber-based building systems. in contrast to the other timber-based building systems, the light-frame and beam-and-column systems require greater amounts of concrete and steel reinforcement for the foundations. (c) massive timber frame (d) beam & column timber frame (e) modular timber frame figure 2. illustrations of structural elements of the conventional (top) and modern construction systems (bottom). table 1. thermal characteristics of the building systems. description reinforced concrete frame light-frame timber frame massive timber frame beam & column timber frame modular timber frame u-value (w/m2 k): roof 0.08 0.08 0.08 0.08 0.08 external wall 0.113 0.113 0.104 0.11 0.111 separating wall 0.161 0.161 0.16 0.215 0.196 internal floors 0.135 0.135 0.127 0.13 0.135 windows 0.8 0.8 0.8 0.8 0.8 doors 0.8 0.8 0.8 0.8 0.8 ground floor 0.108 0.108 0.108 0.108 0.108 infiltration (l/s m2 @ 50 pa) 0.3 0.3 0.3 0.3 0.3 table 2. mass (tonnes) of key materials for the building systems. material reinforced concrete frame light-frame timber frame massive timber frame beam & column timber frame modular timber frame concrete 1361 232 115 180 115 iron/steel 25 16 5 13 4 lumber 44 70 48 25 62 particle board 17 18 6 3 21 plywood 20 21 7 10 laminated wood floor 5 5 5 clt 55 5 5 lvl 61 glulam 20 25 8 insulation 27 38.8 19.1 25.1 22.1 (a) light timber-frame (b) reinforced concrete-frame (c) massive timber frame (d) beam & column timber frame (e) modular timber frame table 2 mass (tonnes) of key materials for the building systems vator shaft is used in the beam-and-column timber and reinforced concrete building systems while wood-constructed elevator shaft is used in the other timber-based building systems. in contrast to the other timber-based building systems, the light-frame and beam-and-column systems require greater amounts of concrete and steel reinforcement for the foundations. material reinforced concrete frame light-frame timber frame massive timber frame beam & column timber frame modular timber frame concrete 1361 232 115 180 115 iron/steel 25 16 5 13 4 lumber 44 70 48 25 62 particle board 17 18 6 3 21 plywood 20 21 7 10 laminated wood floor 5 5 5 clt 55 5 5 lvl 61 glulam 20 25 8 insulation 27 38.8 19.1 25.1 22.1 plasterboard 26 90.4 72 99 105 pvc & polyurethane 2 1.9 4.7 4.4 5.4 mortar 23 25 18 11 11 fig. 2 illustrations of structural elements of the conventional (top) and modern construction systems (bottom) lifecycle studies with attributionalor consequential-based approach are noted in literature. while attributional-based approach mainly characterizes the direct flows linked to a system, typically using average data, consequential-based approach characterizes the system-wide impact of change considering direct and induced effects, typically using marginal data. thus the approach used influence definition of the system boundary and data used in a lifecycle study. using both atmethods 21 journal of sustainable architecture and civil engineering 2019/1/24 tributionaland consequential-based approaches, kua and kamath (2014) modelled the lifecycle implications of replacing concrete with bricks and obtained significantly different results for the approaches. plevin et al. (2014) noted that the two approaches may provide different perspectives and suggested that consequential-based approach can facilitate identification of robust options in the context of climate change mitigation. in this study a consequential-based approach with system perspective is used and the system boundary is defined to include flows in the production, operation and end-of-life stages of the buildings. the functional unit of the analysis is defined at the complete building level and the primary energy use and ghg emissions are expressed in terms of the heated building floor areas. production phase this study used bottom-up models to quantify the production primary energy use of the buildings considering the full natural resource chains, and to track the ghg emissions from fossil fuels combustion and cement process reactions. biomass residues from the wood product chain are increasingly used as bioenergy and the role of bioenergy in the norwegian energy system is suggested to be strengthened (bergseng et al., 2013). this study quantified the potential energy and ghg related benefits that can be derived from recoverable biomass residues from the wooden material chain. a method suggested by gustavsson et al. (2006) is used to calculate the production primary energy and ghg balances of the studied buildings. the primary energy used to extract, process, transport and assemble the materials is calculated, as well as the lower heating values of the logging, processing and construction biomass residues. the ghg emissions from fossil fuel combustion and cement process reactions are calculated, as well as the potential emissions avoided by replacing fossil fuel with recovered forest and processing residues. recoverable forest residues at harvest are based on data from gustavsson and sathre (2006). based on gustavsson and sathre (2006), 70% recovery of available harvest residues and 100% of processing and construction residues are assumed. the assumed lower heating values for the recovered biomass are 4.25 kwh/ kg dry biomass for bark and harvest residues, 4.62 kwh/kg dry biomass for processing residues, and 5.17 kwh/kg dry biomass for recovered post-use wood (gustavsson and sathre, 2006). the amount of diesel fuel used for biomass recovery, expressed in terms of the heating value of the biomass, is assumed to be 1% for processing residues and 5% for harvest residues (gustavsson and sathre, 2006). specific final energy for building material production is based on data from norwegian sources (fossdal, 1995) as well as ecoinvent (2012). these are supplemented with closely related data (björklund and tillman, 1997). the primary energy use is computed assuming fuel cycle energy inputs of 10% for coal, and 5% for oil and natural gas, based on gustavsson et al. (2010). for the electricity to manufacture the materials, 95% is assumed to be covered by a standalone biomass-fired steam turbine (bst) base-load plant, with light-oil gas turbines covering the remainder as peak-load. the conversion efficiencies of the bst plant and the light-oil gas turbines plants are assumed to be 40% and 34%, respectively. electricity distribution loss is assumed to be 2%. the fuel-cycle carbon intensity of the fossil fuels are assumed to be 30, 22 and 18 kg c/kwh end-use fuel for coal, oil, and fossil gas, respectively (gustavsson and sathre, 2006). the biogenic carbon storage sequestered or released from wood materials is not included in the inventory as the wood is assumed to come from sustainably managed forestry, where carbon flows out of the forest are balanced at the landscape level by carbon uptake by growing trees. the primary energy and ghg for on-site construction and assembly are typically small compared to those for material production (gustavsson et al., 2010), and depend on different factors including the type of construction material used and building system. adalberth (2001) estimated the building construction energy to constitute 4% of the energy for material production and transport for the reference building. this percentage is applied to the studied building systems due to data constraints journal of sustainable architecture and civil engineering 2019/1/24 22 for each of the systems. based on the estimated on-site construction and assembly primary energy use, we calculated the associated ghg emission assuming that half of the energy used, counted as primary energy use, is electricity-based, and other half is fossil fuel (diesel)-based. operation phase the annual operation final energy use for space heating, ventilation, domestic hot water heating and household electricity provisions for the buildings are calculated hour-by-hour with the vip-energy program (strusoft, 2010). the space heating demands of the buildings are calculated for the climate of oslo (lat. 59o54’ n; long. 10o45’ e), with assumed indoor temperatures of 22 and 18o c in the living and common areas of the buildings, respectively. the climate dataset of oslo for the period 2000-2009 is used for the calculations and the maximum, average and minimum annual outdoor temperatures during this period were 26, 9 and -9 oc, respectively. the internal heat gains from persons and electric process or activities within the buildings are based on default values in the vip-energy program and are 1.16 w/m2 heat from persons and 4.3 w/m2 from processes including electrical appliances and lighting. based on the operation final energy use, we calculate the operation primary energy use and ghg emissions using the ensyst software (karlsson, 2003). this software estimates primary energy use and ghg emission taking into account the entire energy chain from natural resources extraction to supply of final energy. we consider two different end-use heating systems: bedrock heat pump or district heating. for the heat pump, 95% of the electricity is assumed to be supplied from stand-alone bst plant and the remaining from light-oil gas turbine. the district heating is assumed to be supplied from combined heat and power (chp) plant and heat-only boilers (hob). as the chp plant cogenerates heat and electricity, an allocation issue may arise. in this study we use the subtraction method to calculate the primary energy use for heat, considering the cogenerated electricity to replace electricity that would instead have been produced in a stand-alone plant using the same fuel and technology as the chp plant (gustavsson and karlsson, 2006). the primary energy used for the replaced electricity in the stand-alone plant is subtracted from the chp plant to obtain the primary energy for the heat (gustavsson and karlsson, 2006). end-of-life phase the end-of-life analysis is based on a methodology developed by dodoo et al. (2009) and accounts for the energy and ghg flows associated with the demolition, transportation and processing of the post-use materials. the primary energy use and fossil ghg emissions avoided due to end-of-life material management are considered in the calculations. based on dodoo et al. (2009), 90% of the demolished concrete, steel and wood materials are assumed to be recovered or recycled. the demolished concrete is assumed to be crushed into aggregate followed by exposure to air for a 4-month period to increase carbonation uptake of co2. the recycled aggregate is assumed to be used for below-ground filling applications, substituting virgin aggregate. the post-use steel is assumed to be recycled as feedstock for production of new scrap-based steel reinforcement. the demolished wood is assumed to be recovered of energy through combustion, replacing fossil coal. complete lifecycle the total primary energy use and ghg emissions for the buildings are calculated for a 50-year period. results the primary energy for material production for the studied building systems, including the energy for extraction, processing and transportation, are shown in table 3, divided into different end-use energy carriers: fossil fuels, biomass and electricity. positive numbers denote energy use and negative numbers denote energy that is available from recovered biomass residues. the total production primary energy balances for the building systems are also shown (in table 3) and is lowest for the massive timber building and greatest for the reinforced concrete building. 23 journal of sustainable architecture and civil engineering 2019/1/24 table 3 production primary energy balances for the building systems description primary energy (kwh/m2) reinforced concrete light-frame timber massive timber beam-andcolumn timber modular timber material production fossil fuels 480 401 332 389 377 electricity 306 233 220 271 265 bioenergy 26 42 112 115 56 total 812 676 664 775 698 building construction fossil fuel 16 14 13 16 14 electricity 16 14 13 16 14 total 32 28 26 32 28 production primary energy use 844 704 690 807 726 biomass residue recovery forest harvest -103 -150 -252 -227 -153 wood processing -218 -341 -691 -619 -344 construction -35 -48 -63 -55 -48 total -356 -539 -1005 -901 -546 production primary energy balance 448 165 -315 -94 180 table 4 production ghg balances for the building systems description ghg balance (kg co2/m 2) reinforced concrete light-frame timber massive timber beam-andcolumn timber modular timber material production fossil fuels 161 126 103 120 116 electricity 12 9 9 11 10 net cement reactiona 75 15 8 11 7 total 248 150 120 142 133 building construction fossil fuel 5 5 4 5 5 electricity 1 1 1 1 1 total 6 6 5 6 6 total production co2 emission 254 156 125 148 139 carbon avoided, stock and flow forest harvest biomass residues -39 -56 -95 -85 -58 wood processing biomass residues -78 -122 -248 -223 -124 construction biomass residues -13 -17 -23 -20 -17 residues recovery (fossil fuel used) 3 5 7 6 5 total -127 -190 -359 -322 -194 production carbon balance 127 -34 -234 -174 -55 a net cement reaction is the calcination emission minus carbonation uptake for the 50-year service-life table 4 shows the production ghg balances for the building system versions including flows to the atmosphere (positive numbers) and emission avoided (negative numbers). the net cement reaction is the calcination emission minus carbonation uptake during the 50-year service-life. journal of sustainable architecture and civil engineering 2019/1/24 24 the increase in material production ghg emission of the reinforced concrete building system compared to the timber building systems ranges from 40% to 52%. table 5 presents the annual final operation energy for the building systems, including space heating, tap water heating, ventilation electricity and household and facility electricity. household electricity dominates the buildings’ final operation energy use. the space heating demand for the concrete-frame building is slightly lower than those for the timber-based alternatives due to the thermal mass effect. table 5 annual final energy use for operation of the buildings located in oslo description final energy use (kwh/m2/year ) reinforced concrete light-frame timber massive timber beam-and-column timber modular timber space heating 18.5 18.8 18.8 18.8 18.8 tap water heating 15.0 15.0 15.0 15.0 15.0 ventilation electricity 5.1 5.1 5.1 5.1 5.1 household electricity 30.0 30.0 30.0 30.0 30.0 facility electricity 15.0 15.0 15.0 15.0 15.0 total from operation 83.6 83.9 83.9 83.9 83.9 table 6 annual primary energy use and ghg emission of the buildings located in oslo description primary energy use (kwh/m2) ghg emission (kg co2-eq/m 2) reinforced concrete lightframe timber massive timber frame beam & column timber modu lar timber reinforced concrete lightframe timber massive timber frame beam & column timber mo dular timber heat pump heated: space heating 19.0 19.3 19.3 19.3 19.3 0.7 0.7 0.7 0.7 0.7 tap water heating 15.4 15.4 15.4 15.4 15.4 0.6 0.6 0.6 0.6 0.6 ventilation electricity 13.4 13.4 13.4 13.4 13.4 0.5 0.5 0.5 0.5 0.5 household electricity 78.7 78.7 78.7 78.7 78.7 2.9 2.9 2.9 2.9 2.9 facility electricity 39.4 39.4 39.4 39.4 39.4 1.5 1.5 1.5 1.5 1.5 total from operation 165.9 166.2 166.2 166.2 166.2 6.1 6.1 6.1 6.1 6.1 district heated: space } heating 12.2 12.4 12.4 12.4 12.4 0.4 0.4 0.4 0.4 0.4 tap water heating 9.9 9.9 9.9 9.9 9.9 0.3 0.3 0.3 0.3 0.3 ventilation electricity 13.4 13.4 13.4 13.4 13.4 0.5 0.5 0.5 0.5 0.5 household electricity 78.7 78.7 78.7 78.7 78.7 2.9 2.9 2.9 2.9 2.9 facility electricity 39.4 39.4 39.4 39.4 39.4 1.5 1.5 1.5 1.5 1.5 total from operation 153.6 153.8 153.8 153.8 153.8 5.6 5.7 5.7 5.7 5.7 25 journal of sustainable architecture and civil engineering 2019/1/24 the annual operation primary energy use and ghg emissions of the building versions located in oslo and heated with different systems are shown in table 6. the annual operation primary energy use and ghg emission are both reduced by between 7-8 % when the buildings are heated with district heat instead of with electric-based heat pump. table 7 illustrates the primary energy and ghg balances for the end-of-life phase of the building versions. the primary energy and ghg benefits of demolished wood are considerable while recycling concrete results in small primary energy and ghg benefits. the benefit from recycling of concrete and steel are biggest for the reinforced concrete building systems. table 7 primary energy and ghg balances for endof-life management of the buildings description primary energy use (kwh/m2) ghg emission (kg co2-eq/m 2) reinforced concrete lightframe timber massive timber frame beam & column timber mo dular timber reinforced concrete lightframe timber massive timber frame beam & column timber mo dular timber demolition energy 20 10 10 10 10 6 3 3 3 3 end-of-life benefits: concrete recycling -19 -3 -2 -2 -2 -7 -1 -1 -1 -1 steel recycling -96 -60 -14 -35 -10 -34 -21 -12 -12 -3 wood recovery for bioenergy -220 -340 -502 -441 -385 -85 -123 -203 -178 -156 total -315 -393 -508 -468 -387 -120 -142 -213 -188 -157 fig. 3 shows the primary energy and ghg emissions for production, space heating and ventilation during 50 years, and end-of-life for the buildings when heated with district heating. the operation phase dominates the lifecycle primary energy use of the building systems. material fig. 3 primary energy use (left) and ghg emissions (right) for the lifecycle phases of the district heated buildings for the 50-year period demolition ventilation electricity space heating building construction material production demolition wood production biomass residues steel recycling concrete recycling and carbonation -2000 -1000 0 1000 2000 3000 pr im ar y an d em bo di ed e ne rg y (k w h/ m 2 ) reinforced concreteframe lightframe timber massive timberframe beam & column timber modular timber -600 -400 -200 0 200 400 g re en ho us e ga s em is si on a nd s to ck ( kg c o 2/ m 2 ) reinforced concreteframe lightframe timber massive timberframe beam & column timber modular timber journal of sustainable architecture and civil engineering 2019/1/24 26 production accounts for a large share of the lifecycle ghg emission for the buildings as heat supply is from biomass-based district heating. overall, the timber-based building systems have negative net ghg balances over their complete lifecycle due to the benefits of recovery of production biomass residues for use as fuel and the recovery as well as recycling of the end-of-life materials. the massive timber building gives the lowest lifecycle primary energy use and ghg emission while the reinforced concrete building results in the greatest lifecycle impacts among the analysed building systems. discussion this study has explored the lifecycle primary energy and ghg implications of conventional and modern multi-storey building systems designed to the norwegian passive house criteria with different structural frame materials. the explored buildings have concrete or timber structural framework and the analysis covered the production, operation and end-of-life phases. the analysis shows that the choice of structural frame material as well as building system has significant effect on the primary energy use and climate impact of buildings. the primary energy for building production is 4-18% lower for the analysed timber-based building systems compared to the reinforced concrete building alternative. correspondingly, the timber-based building systems give 39-51% lower ghg emissions for building production in contrast to the reinforced concrete building alternative. this finding corroborates current findings in literature e.g. gustavsson et al. (2006) and dodoo et al. (2009). the operation phase dominates the lifecycle primary energy use of the buildings and the reinforced concrete-frame building gives about 0.2% lower space heating primary energy demand compared to the timber-based building systems, due to the benefits of thermal mass. the operation primary energy use and ghg emissions for the buildings are lower when heated with cogenerated district heating compared to when heated with electric-based heat pump, showing the importance of heat supply system. large amounts of biomass residues are produced for the timber-based building systems and the energy content of the residues is significant relative to the primary energy used for production of the timber-based building systems. for the massive timber and beam-and-column timber systems, the energy content of the recoverable residues more than offset the primary energy required for material production and construction process. in contrast to the post-use steel and concrete materials, the end-of-life management for the wood-based material resulted in significant primary energy and ghg benefits. the lifecycle impacts are lower for the timber-based building systems than for the reinforced concrete building system, due primarily to the lower production primary energy as well as fossil energy use, and greater amount of biomass residues when using wood materials. these advantages more than outweigh the energy saving benefits of thermal mass of the concrete structure. the massive timber building system gives the lowest lifecycle primary energy and ghg balances. except for the modular timber-frame building system, the modern building systems outperform the conventional alternative building systems in terms of lifecycle primary energy use and ghg emissions. the results of this study show that overall lifecycle impacts, including primary energy use and ghg emission for production, operation and end-of-life management are lower for timber-frame buildings than for alternative building with reinforced concrete-frame. this is due mainly to the lower production primary energy use and ghg emissions, and also greater amount of biomass residues recoverable from the wood product chain. this analysis indicates that choice of heat supply system has significant effect on the life cycle impact of buildings. in summary, timber-based buildings and efficient heat supply systems are conclusions 27 journal of sustainable architecture and civil engineering 2019/1/24 of great importance for a low energy building and should be an integral part of the effort to create a resource efficient low carbon built environment. references adalberth, k., almgren, a. & petersen, e. h. life-cycle assessment of four multi-family buildings. international journal of low energy & sustainable buildings, 2001. aye, l., ngo, t., crawford, r., gammampila, r. & mendis, p. life cycle greenhouse gas emissions and energy analysis of prefabricated reusable building modules. energy & buildings, 2012, 47: 159-168. https://doi.org/10.1016/j.enbuild.2011.11.049 bergseng, e., eid, t., løken, ø. & astrup, r. harvest residue potential in norway–a bio-economic model appraisal. scandinavian journal of forest research, 2013, 28, 470-480. https://doi.org/10.10 80/02827581.2013.766259 björklund, t. & tillman, a.-m. lca of building frame structures: environmetal impact over the life cycle of wooden and concrete frames; 1997. bp. bp energy outlook, 2018. available at https:// www.bp.com. cabeza, l. f., rincón, l., vilari-o, v., pérez, g. & castell, a. life cycle assessment (lca) and life cycle energy analysis (lcea) of buildings and the building sector: a review. renewable & sustainable energy reviews, 2014, 29: 394-416. https://doi. org/10.1016/j.rser.2013.08.037 dahlstrøm, o., sørnes, k., eriksen, s. t. & hertwich, e. g. life cycle assessment of a single-family residence built to either conventional-or passive house standard. energy & buildings, 2012, 54: 470-479. dodoo, a., gustavsson, l. & sathre, r. carbon implications of end-of-life management of building materials. resources, conservation & recycling, 2009, 53: 276-286. https://doi.org/10.1016/j.resconrec.2008.12.007 ecoinvent, the ecoinvent database, 2012. fossdal, s. energi-og miljøregnskap for bygg (energy and environmental accounts of building construction). report 173, the norwegian institute of building research, oslo; 1995. gustavsson, l., joelsson, a. & sathre, r. life cycle primary energy use and carbon emission of an eight-storey wood-framed apartment building. energy & buildings, 2010, 42: 230-242. https://doi. org/10.1016/j.enbuild.2009.08.018 gustavsson, l. & karlsson, å. co2 mitigation: on methods and parameters for comparison of fossil-fuel and biofuel systems. mitigation & adaptation strategies for global change, 2006, 11: 935959. https://doi.org/10.1007/s11027-006-9028-7 gustavsson, l., pingoud, k. & sathre, r. carbon dioxide balance of wood substitution: comparing concrete-and wood-framed buildings. mitigation and adaptation strategies for global change, 2006, 11: 667-691. https://doi.org/10.1007/s11027-0067207-1 gustavsson, l. & sathre, r. variability in energy and carbon dioxide balances of wood and concrete building materials. building and environment, 2006, 41:940-951. https://doi.org/10.1016/j.buildenv.2005.04.008 iea. key world energy statistics, international energy agency; 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2010. available from http://www.strusoft.com on 10/01/2017. journal of sustainable architecture and civil engineering 2019/1/24 28 suzuki, m., oka, t. & okada, k. the estimation of energy consumption and co2 emission due to housing construction in japan. energy & buildings, 1995, 22:165169. https://doi.org/10.1016/0378-7788(95)00914-j tek 10. norwegian building code, 2010. available at http://dibk.no tettey, u. y. a., dodoo, a. & gustavsson, l. effects of different insulation materials on primary energy and co2 emission of a multi-storey residential building. energy & buildings, 2014, 82: 369-377. https://doi.org/10.1016/j.enbuild.2014.07.009 thormark, c. a low energy building in a life cycle-its embodied energy, energy need for operation and recycling potential. building & environment, 2002, 37: 429-435. https://doi.org/10.1016/s03601323(01)00033-6 ambrose dodoo associate professor linnaeus university, department of building technology main research area life cycle analysis, building simulation, hvac systems analysis, building technology address georg lückligs 1, växjö, se-35195, sweden tel. 00 46 (0) 470 767812 e-mail: ambrose.dodoo@lnu.se about the author 87 journal of sustainable architecture and civil engineering 2020/1/26 *corresponding author: mindaugas.dauksys@ktu.lt research on the concrete mixture stability and sliding on the inclined plane received 2019/01/15 accepted after revision 2019/09/20 journal of sustainable architecture and civil engineering vol. 1 / no. 26 / 2020 pp. 87-97 doi 10.5755/j01.sace.26.1.21714 research on the concrete mixture stability and sliding on the inclined plane jsace 1/26 http://dx.doi.org/10.5755/j01.sace.26.1.21714 rokas kudirka, mindaugas daukšys*, svajūnas juočiūnas kaunas university of technology, faculty of civil engineering and architecture studentu str. 48, lt-51367 kaunas, lithuania introduction the stability of conventional concrete mixture was investigated using an inclined plane method. the experiment consisted of two steps: first, the research was conducted to obtain an effect of coarse aggregate content in aggregates mixture on the stability and sliding of concrete mixture, when the samples of fresh concrete are on the inclined plane without additional roughening of surface; second, the research was conducted to obtain an effect of inclined plane surface roughening on the stability and sliding of fresh concrete samples. during the research the condition was checked: the fresh concrete on the sloping plane will be stable, if the yield stress τ0 is higher than the shear stress τ in. (τ 0 ≥ τ). the shear stresses and rheological property yield stresses of conventional concrete mixtures were calculated analytically by using an empirical formula. test results showed that the increase of coarse aggregate (4/16 fraction gravel) content from about 417 to 1175 kg in concrete mixture is enough to achieve the stability of fresh concrete, when plane inclination angles are 25°, 35° and 45°, but not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. by using the inclined planes, which were coated with a special dimpled membrane and geotextile, the fresh concrete does not slide downwards by inclined plane. this article is based on master thesis topic “investigations of sloping concrete concreting technologies”. keywords: inclined plane method, concrete mixture, coarse aggregate, yield stress, sliding, roughening. in modern buildings slope-type structures (arched, sloping and dome structures, reservoirs) are common, and different concrete technologies are applied for their installation. performing concrete work of such structures it is necessary to properly solve the conditions of the concrete mix, i.e. to select such concrete technological parameters (žiogas et al. 2012) so that the concrete mixture does not slides down and is well laid and packed. one of the concrete mixture’s rheological properties (in order to maintain the concrete mixture’s stability at an angle of inclination of the inclined plane) is yield stress that must be not less than a certain size. yield stress may be calculated by analysing the forces acting on the concrete mixture and the shear stresses it produces, depending on the angle of the plane inclination (coussot and boyer, 1995; assaad and khayat, 2004; banfill, 2006; khayat and omran, 2009; khayat et al. 2010). the relation between the flow factor of the concrete mixture and the yield stresses, when the components of the concrete mix change, were studied by the authors (wallevik, 2003; kamal et al. 2010). journal of sustainable architecture and civil engineering 2020/1/26 88 fresh concrete mixture is a heterogeneous suspension which consists of various constituents. those various constituents distinguish in different shape, size, material properties and has an effect on workability of fresh concrete (jiao et al. 2017). cement paste is one of the main constituent parts of concrete, which covers aggregates and fills gaps between them, and makes the flow of concrete mix easier. koehler and fowler (2004) confirmed that the increased volume of paste increases the flow factor and thus reduces yield stresses and plastic viscosity. authors (mork and gjorv, 1997; chen and kwan, 2012; dils et al. 2013) in their works concluded, that the yield stresses and plastic viscosity of cement paste depend on the mineral composition of the cement. it is estimated that in cement which contains high amount of c3a and alkaline, the reduction of gypsum to silica ratio reduced the yield stresses, but did not change the plastic viscosity. the aggregate type has an effect on the technology of concrete due to its bulk density and surface morphology. crushed rock aggregates distinguish in angular shape and rough surface. this increase their surface area and reduce the amount of free water during mixture preparation. in addition, the angular shape is not favourable for particle flow and increases the resistance of friction between particles, thus significantly increasing the yield stresses and plastic viscosity, reducing the flow of the mixture (westerholm et al. 2008; aissoun et al. 2016). the main rheological properties of concrete mixture – yield stresses and plastic viscosity significantly depend on the type of aggregate, its chemical composition and content in the aggregate mixture, its packing density, fineness and surface texture (jiao et al. 2017). in addition, that strongly depend on particle size distribution of mineral admixtures, its filling, morphology, dispersion and adsorption effects. in many studies (ba and zhang, 2003; hu and wang, 2011; harini et al. 2012; zhang et al. 2016) it was estimated that the yield stresses and plastic viscosity of the concrete mixture increase as the volume of a coarse aggregate increases, while increasing the amount of fine aggregate increases the yield stresses of the concrete mixture, but decreases the plastic viscosity. the addition of coarse aggregates increases the amount of mortar covering the surface of the aggregates, reduces the cohesive effect between the aggregates and the cement paste and reduces the friction between the aggregates. by increasing the volume of fine aggregates, the need for hard particle surface area and water increases, the friction between the coarse aggregates decreases, therefore the shear stresses are increased and the plastic viscosity is reduced. it was also concluded that the larger the size of maximum particles, the smaller the specific surface area and less mortar (cement paste) is required to cover the aggregates, and at the same time the smaller the values of rheological properties of the concrete mix, the less dilatation (increase of mixture viscosity while shear stresses increase) is expressed in mixture (santos et al. 2015). the aim of this study is to determine an effect of coarse aggregate content in the total aggregates mixture on the stability and sliding of fresh concrete, when the samples of fresh concrete are on the inclined plane without and with additional roughening of surface. portland cement type cem i 42.5 r from jsc “akmenės cementas” (lithuania) was used. the physical and mechanical properties of portland cement are presented in table 1. the fine aggregate washed sand sourced from “kvesu quarry“ (lithuania) with the fractions of 0/1 and 0/4 was used. following charactermaterials and testing methods table 1 physical and mechanical properties of portland cement cem i 42.5 r fineness by blaine air-permeability apparatus, m2/kg 410 specific gravity, kg/m3 3050 dry bulk density, kg /m3 1230 normal consistency by vicat apparatus, % 26,5 volume expansion, mm 0.8 initial time of setting by vicat apparatus, min 195 2/28 days compressive strength, mpa 27.1/54.0 89 journal of sustainable architecture and civil engineering 2020/1/26 istics were determined: bulk densities of 1521 kg/m3 and 1711 kg/m3, particles densities of 2655 kg/m3 and fineness modules of 1.78 and 2.62. the coarse aggregate gravel with the fraction of 4/16 was used. following characteristics were determined: bulk density of 1657 kg/m3 and particle density of 2665 kg/m3. characteristics of the aggregates in accordance to the standard lst en 12620 are presented in table 2. the plasticizing admixture glenium sky 628 supplied by basf (italy), based on polycarboxylate resin was used for the research. technical data: the table 2 fine and coarse aggregates granulometric composition size of the sieve mesh, mm the partial residue, % sand fraction 0/1 sand fraction 0/4 gravel fraction 4/16 32.0 100.0 16.0 93.0 8.0 100.0 100.0 25.4 4.0 100.0 97.5 0.4 2.0 99.9 87.7 0 1.0 98.1 71.9 0 0.500 92.5 56.0 0 0.250 28.0 17.4 0 0.125 3.2 4.6 0 0 0 0 0 density of water solution 1.06 kg/l; brown liquid; chloride quantity <0.1%; alkali quantity <2.5%. it was added in amount of 1.0% by weight of cement. the form release agent rheofinish 215 supplied by basf (korea) was used. technical data: the density of water solution 0.96 kg/l; white liquid; viscosity 30 mpa·s; ph value – 8.5; temperature of using from 0°c to +20±5°c. formwork surface (plywood) was covered within the excessive amount of form release agent and then was cleaned by the soft cloth according to producer recommendation. the concrete mixtures were prepared according to the requirements of standard lst en 206 using dry materials. in the laboratory, the concrete mixtures were mixed using forced type concrete mixer zyklos rotating pan mixer. the process of preparation of concrete mixture was divided into two stages. at the first stage, cement, fine and coarse aggregates and 2/3 of water were mixed for about 2 minutes. at the second stage, the remaining amount of water was added with plasticizing admixture and mixed for about 1 minute. during the mixing process, cement, fine and coarse aggregates were dosed by weight while water and plasticizing admixture were dosed by volume. the consistency of fresh concrete was determined in accordance to the standard lst en 12350-2, the density of fresh concrete in accordance to the standard lst en 12350-5:2009 and the air content of the compacted fresh concrete in accordance to lst en 12350-7. the inclined phenolic formwork plywood planes were coated with a special dimpled membrane guttabeta drain (gutta switzerland) and geotextile duponttm geoproma® (dupont de nemours luxembourg s.à r.l). membrane (fig. 1a) is made from high-density polyethylene (hdpe), stud height approx. 8 mm, studs per 1860 piece/m2, air volume between studs approx. 5.3 l/m2. geotextile (fig. 1b) is made from a 100 % thermally bonded polypropylene, unit weight 90 g/m2, tensile strength 5.0 kn/m, elongation (max. strength) 40 %, opening size 175 μm. uniformity of surface roughness of used materials for plywood planes coating was not obtained. for the inclined plane (ip) method a truncated cone of 100 mm in height, of 100 mm in diameter at the top and of 200 mm in diameter at the bottom was used. at the beginning, the truncated cone was placed on the top of inclined plane, filled with fresh concrete and it compacted by rod 10 times. after the cone was removed immediately in one move, the time of concrete mixture sample sliding downward was measured. if some part of the sample slides down along an inclined plane, this journal of sustainable architecture and civil engineering 2020/1/26 90 concrete mixture isn’t stable. according to literature review were chosen three angle of the plane inclination: 25°, 35° and 45°. view of the inclined planes are given in figs 4 and 5. the shear stresses τ in the concrete mixture results from the tangential component of the force of gravity (khayat and omran, 2009). shear stress can be calculated according to equation (1): τ = ρm ∙ g ∙ h ∙ sinα; (1) here: ρm – the density of fresh concrete, g/cm 3; g – the constant of gravitation (9.81 m/s2); h – the characteristic height of spread concrete sample, cm; α – the angle of the plane inclination, °. from eq. 1 we can see that the shear stresses in a fresh concrete depends on the characteristic height h of spread sample and the angle α of the plane inclination. the concrete mixture will be stable on a sloping plane if its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete: τ0 ≥ τ (2) the yield stress values for all concrete mixture composition were calculated in accordance with equation (3). for calculation was used an empirical formula proposed by skripkiūnas (1993): ; 024.0001724.0 30 498.0 00815.0 20             sl m (3) here: τ0 – the yield stress of fresh concrete, pa; ρm – the density of fresh concrete, kg/m3; sl – the slump value of fresh concrete, cm. sliding speed of concrete mixture specimen moving down plane with different angle of the plane inclination can be calculated according to equation (4): v = s/t; (4) here: v – sliding speed of concrete mixture specimen moving down plane, cm/s; d – total distance of travel, cm; t – total time, when the specimen reach the bottom, s. results one of the aims of the research was to investigate an effect of coarse aggregate – gravel of fraction 4/16 mm quantity on the technological and rheological properties of fresh concrete with increasing the quantity of coarse aggregate and decreasing the total quantity of sand (fraction 0/1 mm and fraction 0/4 mm) in the total aggregates mixture. the content of gravel of fraction 4/16 mm was changed from 22 to 62% according to mass in respect to total aggregates mixture content. the mixture compositions for all concretes (bt1-0 – bat-6) used in this research are presented in table 3. table 3. mixtures compositions materials u ni t the mark of concrete mixture proportion. the amount of materials per cu. m. of concrete mixture, kg bt1-0 bt1-1 bt1-2 bt1-3 bt1-4 bt1-5 bt1-6 cem i 42.5 r kg 330 330 330 330 330 330 330 water l 178 178 178 178 178 178 178 water to cement ratio 0.54 0.54 0.54 0.54 0.54 0.54 0.54 coarse aggregate ratio to total aggregate mixture 0.22 0.32 0.37 0.42 0.47 0.52 0.62 sand of fraction 0/1 mm kg 492 429 397 366 334 303 240 sand of fraction 0/4 mm kg 986 860 797 733 671 607 480 gravel of fraction 4/16 mm kg 417 607 702 796 891 986 1175 superplasticizer kg/l 3.74 3.74 3.74 3.74 3.74 3.74 3.74 the influence of gravel content in the total aggregates mixture on the entrapped air content in fresh concrete (a) and the density of fresh concrete (b) is presented in figs 2. from fig. 2a we can see that by increasing the content of gravel (fraction 4/16) in the total aggregates mixture from 22 to 62%, the entrapped air content in fresh concrete decreases from 7.9 to 1.4%. the entrapped air content in fresh concrete is lowest when the gravel (fraction 4/16) content in the total aggregates mixture is about 62% (the fine aggregate content is decrease to 38%, respectively). the function graph (fig. 2b) shows that when the content of gravel (fraction 4/16) in the total aggregates mixture increases from 22 to 62%, the density of fresh concrete increases from 2160 to 2420 kg/m3. when particles have a larger distribution density and a smaller surface area, the entrapped air content in fresh concrete is lower, while the density of fresh concrete is higher. ; (3) here: τ0 – the yield stress of fresh concrete, pa; ρm – the density of fresh concrete, kg/m3; sl – the slump value of fresh concrete, cm. sliding speed of concrete mixture specimen moving down plane with different angle of the plane inclination can be calculated according to equation (4): v = s/t; (4) here: v – sliding speed of concrete mixture specimen moving down plane, cm/s; d – total distance of travel, cm; t – total time, when the specimen reach the bottom, s. fig. 1 for plywood plane surface roughening used materials: membrane (a) and geotextile (b) elongation (max. strength) 40 %, opening size 175 μm. uniformity of surface roughness of used materials for plywood planes coating was not obtained. a b figure 1. for plywood plane surface roughening used materials: membrane (a) and geotextile (b) for the inclined plane (ip) method a truncated cone of 100 mm in height, of 100 mm in diameter at the top and of 200 mm in diameter at the bottom was used. at the beginning, the truncated cone was placed on the top of inclined plane, filled with fresh concrete and it compacted by rod 10 times. after the cone was removed immediately in one move, the time of concrete mixture sample sliding downward was measured. if some part of the sample slides down along an inclined plane, this concrete mixture isn’t stable. according to literature review were chosen three angle of the plane inclination: 25°, 35° and 45°. view of the inclined planes are given in figs 4 and 5. the shear stresses τ in the concrete mixture results from the tangential component of the force of gravity (khayat and omran, 2009). shear stress can be calculated according to equation (1): τ = ρmˑgˑhˑsinα (1) here: ρm – the density of fresh concrete, g/cm3; g – the constant of gravitation (9.81 m/s2); h – the characteristic height of spread concrete sample, cm; α – the angle of the plane inclination, °. from eq. 1 we can see that the shear stresses in a fresh concrete depends on the characteristic height h of spread sample and the angle α of the plane inclination. the concrete mixture will be stable on a sloping plane if its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete: τ0 ≥ τ (2) the yield stress values for all concrete mixture composition were calculated in accordance with equation (3). for calculation was used an empirical formula proposed by skripkiūnas (1993): elongation (max. strength) 40 %, opening size 175 μm. uniformity of surface roughness of used materials for plywood planes coating was not obtained. a b figure 1. for plywood plane surface roughening used materials: membrane (a) and geotextile (b) for the inclined plane (ip) method a truncated cone of 100 mm in height, of 100 mm in diameter at the top and of 200 mm in diameter at the bottom was used. at the beginning, the truncated cone was placed on the top of inclined plane, filled with fresh concrete and it compacted by rod 10 times. after the cone was removed immediately in one move, the time of concrete mixture sample sliding downward was measured. if some part of the sample slides down along an inclined plane, this concrete mixture isn’t stable. according to literature review were chosen three angle of the plane inclination: 25°, 35° and 45°. view of the inclined planes are given in figs 4 and 5. the shear stresses τ in the concrete mixture results from the tangential component of the force of gravity (khayat and omran, 2009). shear stress can be calculated according to equation (1): τ = ρmˑgˑhˑsinα (1) here: ρm – the density of fresh concrete, g/cm3; g – the constant of gravitation (9.81 m/s2); h – the characteristic height of spread concrete sample, cm; α – the angle of the plane inclination, °. from eq. 1 we can see that the shear stresses in a fresh concrete depends on the characteristic height h of spread sample and the angle α of the plane inclination. the concrete mixture will be stable on a sloping plane if its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete: τ0 ≥ τ (2) the yield stress values for all concrete mixture composition were calculated in accordance with equation (3). for calculation was used an empirical formula proposed by skripkiūnas (1993): (a) (b) one of the aims of the research was to investigate an effect of coarse aggregate – gravel of fraction 4/16 mm quantity on the technological and rheological properties of fresh concrete with increasing the quantity of coarse aggregate and decreasing the total quantity of sand (fraction 0/1 mm and results 91 journal of sustainable architecture and civil engineering 2020/1/26 a b figure 2. the influence of gravel content in the total aggregates mixture on the entrapped air content in fresh concrete (a) and the density of fresh concrete (b) the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete is presented in figs 3. a b figure 3. the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete the function graphs reveal that gravel (fraction 4/16) content in the total aggregates mixture affects the slump and yield stress values of fresh concrete. by increasing the content of gravel (fraction 4/16) in the total aggregates mixture from 22 to 62% (the fine aggregate content decreases from 78 to 38%, respectively), the slump values of fresh concrete increase from 30 to 280 mm and yield stresses values of the concrete decrease from 809.98 to 60.21 pa. calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete with different angle of the plane inclination, when the gravel (fraction 4/16) content in the total aggregates mixture varied in the range from 22 to 62%, are given in table 4. a b figure 2. the influence of gravel content in the total aggregates mixture on the entrapped air content in fresh concrete (a) and the density of fresh concrete (b) the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete is presented in figs 3. a b figure 3. the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete the function graphs reveal that gravel (fraction 4/16) content in the total aggregates mixture affects the slump and yield stress values of fresh concrete. by increasing the content of gravel (fraction 4/16) in the total aggregates mixture from 22 to 62% (the fine aggregate content decreases from 78 to 38%, respectively), the slump values of fresh concrete increase from 30 to 280 mm and yield stresses values of the concrete decrease from 809.98 to 60.21 pa. calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete with different angle of the plane inclination, when the gravel (fraction 4/16) content in the total aggregates mixture varied in the range from 22 to 62%, are given in table 4. (a) (b) fraction 0/4 mm) in the total aggregates mixture. the content of gravel of fraction 4/16 mm was changed from 22 to 62% according to mass in respect to total aggregates mixture content. the mixture compositions for all concretes (bt1-0 – bat-6) used in this research are presented in table 3. table 3 mixtures compositions materials u ni t the mark of concrete mixture proportion. the amount of materials per cu. m. of concrete mixture, kg bt1-0 bt1-1 bt1-2 bt1-3 bt1-4 bt1-5 bt1-6 cem i 42.5 r kg 330 330 330 330 330 330 330 water l 178 178 178 178 178 178 178 water to cement ratio 0.54 0.54 0.54 0.54 0.54 0.54 0.54 coarse aggregate ratio to total aggregate mixture 0.22 0.32 0.37 0.42 0.47 0.52 0.62 sand of fraction 0/1 mm kg 492 429 397 366 334 303 240 sand of fraction 0/4 mm kg 986 860 797 733 671 607 480 gravel of fraction 4/16 mm kg 417 607 702 796 891 986 1175 superplasticizer kg/l 3.74 3.74 3.74 3.74 3.74 3.74 3.74 the influence of gravel content in the total aggregates mixture on the entrapped air content in fresh concrete (a) and the density of fresh concrete (b) is presented in figs 2. from fig. 2a we can see that by increasing the content of gravel (fraction 4/16) in the total aggregates mixture from 22 to 62%, the entrapped air content in fresh concrete decreases from 7.9 to 1.4%. the entrapped air content in fresh concrete is lowest when the gravel (fraction 4/16) content in the total aggregates mixture is about 62% (the fine aggregate content is decrease to 38%, respectively). the function graph (fig. 2b) shows that when the content of gravel (fraction 4/16) in the total aggregates mixture increases from 22 to 62%, the density of fresh concrete increases from 2160 to 2420 kg/m3. when particles have a larger distribution density and a smaller surface area, the entrapped air content in fresh concrete is lower, while the density of fresh concrete is higher. fig. 2 the influence of gravel content in the total aggregates mixture on the entrapped air content in fresh concrete (a) and the density of fresh concrete (b) the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete is presented in figs 3. journal of sustainable architecture and civil engineering 2020/1/26 92 the function graphs reveal that gravel (fraction 4/16) content in the total aggregates mixture affects the slump and yield stress values of fresh concrete. by increasing the content of gravel (fraction 4/16) in the total aggregates mixture from 22 to 62% (the fine aggregate content decreases from 78 to 38%, respectively), the slump values of fresh concrete increase from 30 to 280 mm and yield stresses values of the concrete decrease from 809.98 to 60.21 pa. calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete with different angle of the plane inclination, when the gravel (fraction 4/16) content in the total aggregates mixture varied in the range from 22 to 62%, are given in table 4. fig. 3 the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete table 4 the results of the sliding speed and shear stress of concrete mixtures with different angle of the plane inclination, when the gravel content in the total aggregates mixture increases from 22 to 62% the mark of concrete mixture proportion sliding speed (v) and shear stress (τ) angle of inclination, ° equation c or re la ti on co ef fic ie nt r 25 35 45 bt1-0 v, cm/s 25.90 51.80 98.30 y = 0.1027x2 3.5737x + 51.036 1.00 τ, pa 183.98 412.07 636.90 y = -0.0162x2 + 23.784x 400.46 1.00 bt1-1 v, cm/s 22.80 51.80 142.50 y = 0.3083x2 15.597x + 220.03 1.00 τ, pa 154.25 471.80 811.36 y = 0.1101x2 + 25.15x 543.31 1.00 bt1-2 v, cm/s 14.30 42.50 81.40 y = 0.053x2 0.3525x 10.076 1.00 τ, pa 110.01 461.72 1051.35 y = 1.1896x2 36.208x + 271.69 1.00 bt1-3 v, cm/s 17.50 47.50 158.30 y = 0.4044x2 21.265x + 296.45 1.00 τ, pa 21.81 60.49 60.10 y = -0.1953x2 + 15.585x 245.76 1.00 bt1-4 v, cm/s 33.50 95.00 158.30 y = 0.0093x2 + 5.5882x 112 1.00 τ, pa 15.71 50.83 101.00 y = 0.0753x2 1.007x 6.1822 1.00 bt1-5 v, cm/s 12.10 32.20 63.30 y = 0.0553x2 1.3087x + 10.301 1.00 τ, pa 97.22 393.16 761.78 y = 0.3634x2 + 7.792x 324.68 1.00 bt1-6 v, cm/s 12.10 28.50 63.30 y = 0.0923x2 3.9011x + 51.964 1.00 τ, pa 24.72 149.96 198.67 y = -0.3826x2 + 35.481x 623.17 1.00 a b figure 2. the influence of gravel content in the total aggregates mixture on the entrapped air content in fresh concrete (a) and the density of fresh concrete (b) the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete is presented in figs 3. a b figure 3. the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete the function graphs reveal that gravel (fraction 4/16) content in the total aggregates mixture affects the slump and yield stress values of fresh concrete. by increasing the content of gravel (fraction 4/16) in the total aggregates mixture from 22 to 62% (the fine aggregate content decreases from 78 to 38%, respectively), the slump values of fresh concrete increase from 30 to 280 mm and yield stresses values of the concrete decrease from 809.98 to 60.21 pa. calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete with different angle of the plane inclination, when the gravel (fraction 4/16) content in the total aggregates mixture varied in the range from 22 to 62%, are given in table 4. a b figure 2. the influence of gravel content in the total aggregates mixture on the entrapped air content in fresh concrete (a) and the density of fresh concrete (b) the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete is presented in figs 3. a b figure 3. the influence of gravel content in the total aggregates mixture on the consistency (a) and yield stress (b) of fresh concrete the function graphs reveal that gravel (fraction 4/16) content in the total aggregates mixture affects the slump and yield stress values of fresh concrete. by increasing the content of gravel (fraction 4/16) in the total aggregates mixture from 22 to 62% (the fine aggregate content decreases from 78 to 38%, respectively), the slump values of fresh concrete increase from 30 to 280 mm and yield stresses values of the concrete decrease from 809.98 to 60.21 pa. calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete with different angle of the plane inclination, when the gravel (fraction 4/16) content in the total aggregates mixture varied in the range from 22 to 62%, are given in table 4. (a) (b) 93 journal of sustainable architecture and civil engineering 2020/1/26 results given in table 4 reveals that the angle of the plane inclination affects the sliding speed and shear stress of the fresh concrete samples. by increasing the angle of the plane inclination from 25 to 45°, the sliding speed of fresh concrete sample increase. when the angle of the plane inclination was 45°, was obtained the highest speed 158.3 cm/s (compositions bt1-3 and bt1-4). the lowest speed 12.1 cm/s (compositions bt1-5 and bt1-6) was obtained when the angle of the plane inclination was 25°. when the angle of the plane inclination increases from 25 to 45°, the shear stress of concrete mixture varied in the range from 183.98 to 15.71 pa (when α = 25°), from 412.07 to 50.83 pa (when α = 35°) and from 636.90 to 101.00 pa (when α = 45°). by using microsoft excel program was identified the best dependence between the sliding speed and shear stress values of fresh concrete samples according to the best empirical coefficients values of equations. the empirical coefficient of equation was used to calculate the correlation coefficient or pearson coefficient. it is known that pearson coefficient is evaluating the strength of linear relationship between variables and it should be closer to 1. by determining correlation coefficient, it was decided which equation describes the best distribution of statistical data. table 5 checking if yield stress τ0 is greater than the shear stress τ condition the mark of concrete mixture proportion τ0, pa τ, pa checking if condition τ0 ≥ τ angle of inclination, ° angle of inclination, ° 25 35 45 25 35 45 bt1-0 809.98 183.98 412.07 636.90 stable stable stable bt1-1 736.84 154.25 471.80 811.36 stable stable not stable bt1-2 427.23 97.22 393.16 761.78 stable stable not stable bt1-3 386.68 110.01 461.72 105.35 stable not stable stable bt1-4 337.35 24,72 149.96 198.67 stable stable stable bt1-5 213.09 21.81 60.49 60.10 stable stable stable bt1-6 60.21 15.71 50.83 101.00 stable stable not stable from results given in table 5 we can see that the fresh concrete sample is stable on a sloping plane if its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete. view of the inclined plane (ip) test method is shown in figs 4 (a-c). the samples of fresh concrete are stable, but slides down along an inclined plane, which made form plywood and for roughenfig. 4 view of the inclined plane method test α = 25° α = 35° α = 45° its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete. view of the inclined plane (ip) test method is shown in figs 4 (a-c). the samples of fresh concrete are stable, but slides down along an inclined plane, which made form plywood and for roughening of surface was not used any material. test results (table 5) show that the increase of gravel (fraction 4/16) content from about 417 to 1175 kg in concrete mixture is not enough to achieve the stability of fresh concrete sample, when plane inclination angles are 25°, 35° and 45°. also is not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. it was decided to increase the adhesion of fresh concrete to the base by using special dimpled membrane (fig. 1a) and geotextile (fig. 1b). a) α = 25° b) α = 35° c) α = 45° figure 4. view of the inclined plane method test for the next step of experiment were chosen two concrete mixture composition: bt1-3 and bt1-5. the yield stresses and technological properties of those mixtures are presented in table 6. table 6. comparison of the yield stress and technological properties of concrete mixtures the mark of concrete mixture proportion coarse aggregate ratio to total aggregate mixture air content, % density, kg/m3 slump value, mm τ0, pa bt1-3 0.42 5.2 2279 160 416.09 bt1-5 0.52 4.1 2341 230 207.85 calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete samples, when angle of the plane inclination varied from 25 to 45° and for roughening of plywood surface were used membrane and geotextile, are presented in table 7. when the angle of the plane, which is covered using membrane and geotextile, inclination increases from 25 to 45°, the shear stress of concrete mixture increase. the sliding speed in some cases didn’t its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete. view of the inclined plane (ip) test method is shown in figs 4 (a-c). the samples of fresh concrete are stable, but slides down along an inclined plane, which made form plywood and for roughening of surface was not used any material. test results (table 5) show that the increase of gravel (fraction 4/16) content from about 417 to 1175 kg in concrete mixture is not enough to achieve the stability of fresh concrete sample, when plane inclination angles are 25°, 35° and 45°. also is not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. it was decided to increase the adhesion of fresh concrete to the base by using special dimpled membrane (fig. 1a) and geotextile (fig. 1b). a) α = 25° b) α = 35° c) α = 45° figure 4. view of the inclined plane method test for the next step of experiment were chosen two concrete mixture composition: bt1-3 and bt1-5. the yield stresses and technological properties of those mixtures are presented in table 6. table 6. comparison of the yield stress and technological properties of concrete mixtures the mark of concrete mixture proportion coarse aggregate ratio to total aggregate mixture air content, % density, kg/m3 slump value, mm τ0, pa bt1-3 0.42 5.2 2279 160 416.09 bt1-5 0.52 4.1 2341 230 207.85 calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete samples, when angle of the plane inclination varied from 25 to 45° and for roughening of plywood surface were used membrane and geotextile, are presented in table 7. when the angle of the plane, which is covered using membrane and geotextile, inclination increases from 25 to 45°, the shear stress of concrete mixture increase. the sliding speed in some cases didn’t its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete. view of the inclined plane (ip) test method is shown in figs 4 (a-c). the samples of fresh concrete are stable, but slides down along an inclined plane, which made form plywood and for roughening of surface was not used any material. test results (table 5) show that the increase of gravel (fraction 4/16) content from about 417 to 1175 kg in concrete mixture is not enough to achieve the stability of fresh concrete sample, when plane inclination angles are 25°, 35° and 45°. also is not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. it was decided to increase the adhesion of fresh concrete to the base by using special dimpled membrane (fig. 1a) and geotextile (fig. 1b). a) α = 25° b) α = 35° c) α = 45° figure 4. view of the inclined plane method test for the next step of experiment were chosen two concrete mixture composition: bt1-3 and bt1-5. the yield stresses and technological properties of those mixtures are presented in table 6. table 6. comparison of the yield stress and technological properties of concrete mixtures the mark of concrete mixture proportion coarse aggregate ratio to total aggregate mixture air content, % density, kg/m3 slump value, mm τ0, pa bt1-3 0.42 5.2 2279 160 416.09 bt1-5 0.52 4.1 2341 230 207.85 calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete samples, when angle of the plane inclination varied from 25 to 45° and for roughening of plywood surface were used membrane and geotextile, are presented in table 7. when the angle of the plane, which is covered using membrane and geotextile, inclination increases from 25 to 45°, the shear stress of concrete mixture increase. the sliding speed in some cases didn’t (a) (b) (c) journal of sustainable architecture and civil engineering 2020/1/26 94 ing of surface was not used any material. test results (table 5) show that the increase of gravel (fraction 4/16) content from about 417 to 1175 kg in concrete mixture is not enough to achieve the stability of fresh concrete sample, when plane inclination angles are 25°, 35° and 45°. also is not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. it was decided to increase the adhesion of fresh concrete to the base by using special dimpled membrane (fig. 1a) and geotextile (fig. 1b). for the next step of experiment were chosen two concrete mixture composition: bt1-3 and bt1-5. the yield stresses and technological properties of those mixtures are presented in table 6. the mark of concrete mixture proportion coarse aggregate ratio to total aggregate mixture air content, % density, kg/m3 slump value, mm τ0, pa bt1-3 0.42 5.2 2279 160 416.09 bt1-5 0.52 4.1 2341 230 207.85 table 6 comparison of the yield stress and technological properties of concrete mixtures calculated results of the sliding speed (v) and shear stress (τ) of fresh concrete samples, when angle of the plane inclination varied from 25 to 45° and for roughening of plywood surface were used membrane and geotextile, are presented in table 7. table 7 the results of the sliding speed and shear stress of fresh concrete samples with different angle of the plane inclination, when for roughening of plywood surface were used membrane and geotextile mark of concrete mixture composition sliding speed (v) and shear stress (τ) angle of inclination, ° equation c o rr el at io n co ef fi ci en t r 25 35 45 for roughening of plywood surface was used membrane bt1-3 v, cm/s 0 0 0 τ, pa 281.10 526.51 760.95 y = -5.4835x2 + 261.85x + 24.732 1.00 bt1-5 v, cm/s 0 0 31.70 y = 15.833x 21.111 1.00 τ, pa 212.76 639.16 977.06 y = -44.253x2 + 559.16x 302.14 0.86 for roughening of plywood surface was used geotextile bt1-3 v, cm/s 0 56.40 93.40 y = -9.7143x2 + 85.579x 75.864 1.00 τ, pa 251.51 765.83 1008.25 y = -135.95x2 + 922.16x 534.7 1.00 bt1-5 v, cm/s 0 9.30 50.90 y = 16.102x2 38.962x + 22.86 1.00 τ, pa 212.76 245.83 586.24 y = 153.67x2 427.93x + 487.03 1.00 when the angle of the plane, which is covered using membrane and geotextile, inclination increases from 25 to 45°, the shear stress of concrete mixture increase. the sliding speed in some cases didn’t increase and was equal 0, i.e. sliding process of fresh concrete samples on a sloping plane was stopped (table 7). roughening of plywood surface by using membrane and geotextile affects the sliding process of fresh concrete samples. due to dimpled membrane studs, which are approx. 8 mm height, effect on sliding process is bigger compering to geotextile effect on sliding process. views of the inclined plane (ip) test method, when for roughening of plywood surface were used membrane and geotextile, are presented in figs 6 (a-c) and figs 7 (a-c). 95 journal of sustainable architecture and civil engineering 2020/1/26 from figs 6a and 7a we can see that fresh concrete samples are stable on a sloping plane (when α = 25°) and also didn’t slides down along an inclined plane. figs 6b and 7b show that some part of fresh concrete samples isn’t stable on a sloping plane (when α = 35°) and only unstable part of fresh concrete sample slides down along an inclined plane. figs 6c and 7c show that fresh concrete samples aren’t stable on a sloping plane (when α = 35°) and slides down along an inclined plane. from results given in table 8 we can see that the fresh concrete sample is stable on a sloping plane if its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete. fig. 6 view of the inclined plane test method, when for roughening of plywood surface was used membrane increase and was equal 0, i.e. sliding process of fresh concrete samples on a sloping plane was stopped (table 7). roughening of plywood surface by using membrane and geotextile affects the sliding process of fresh concrete samples. due to dimpled membrane studs, which are approx. 8 mm height, effect on sliding process is bigger compering to geotextile effect on sliding process. table 7. the results of the sliding speed and shear stress of fresh concrete samples with different angle of the plane inclination, when for roughening of plywood surface were used membrane and geotextile mark of concrete mixture composition sliding speed (v) and shear stress (τ) angle of inclination, ° equation correlation coefficient r 25 35 45 for roughening of plywood surface was used membrane bt1-3 v, cm/s 0 0 0 τ, pa 281.10 526.51 760.95 y = -5.4835x2 + 261.85x + 24.732 1.00 bt1-5 v, cm/s 0 0 31.70 y = 15.833x 21.111 1.00 τ, pa 212.76 639.16 977.06 y = -44.253x2 + 559.16x 302.14 0.86 for roughening of plywood surface was used geotextile bt1-3 v, cm/s 0 56.40 93.40 y = -9.7143x 2 + 85.579x 75.864 1.00 τ, pa 251.51 765.83 1008.25 y = -135.95x2 + 922.16x 534.7 1.00 bt1-5 v, cm/s 0 9.30 50.90 y = 16.102x 2 38.962x + 22.86 1.00 τ, pa 212.76 245.83 586.24 y = 153.67x2 427.93x + 487.03 1.00 views of the inclined plane (ip) test method, when for roughening of plywood surface were used membrane and geotextile, are presented in figs 6 (a-c) and figs 7 (a-c). a) α = 25° b) α = 35° c) α = 45° figure 6. view of the inclined plane test method, when for roughening of plywood surface was used membrane from figs 6a and 7a we can see that fresh concrete samples are stable on a sloping plane (when α = 25°) and also didn’t slides down along an inclined plane. figs 6b and 7b show that some part of fresh concrete samples isn’t stable on a sloping plane (when α = 35°) and only unstable part of fresh concrete sample slides down along an inclined plane. figs 6c and 7c show that fresh concrete samples aren’t stable on a sloping plane (when α = 35°) and slides down along an inclined plane. increase and was equal 0, i.e. sliding process of fresh concrete samples on a sloping plane was stopped (table 7). roughening of plywood surface by using membrane and geotextile affects the sliding process of fresh concrete samples. due to dimpled membrane studs, which are approx. 8 mm height, effect on sliding process is bigger compering to geotextile effect on sliding process. table 7. the results of the sliding speed and shear stress of fresh concrete samples with different angle of the plane inclination, when for roughening of plywood surface were used membrane and geotextile mark of concrete mixture composition sliding speed (v) and shear stress (τ) angle of inclination, ° equation correlation coefficient r 25 35 45 for roughening of plywood surface was used membrane bt1-3 v, cm/s 0 0 0 τ, pa 281.10 526.51 760.95 y = -5.4835x2 + 261.85x + 24.732 1.00 bt1-5 v, cm/s 0 0 31.70 y = 15.833x 21.111 1.00 τ, pa 212.76 639.16 977.06 y = -44.253x2 + 559.16x 302.14 0.86 for roughening of plywood surface was used geotextile bt1-3 v, cm/s 0 56.40 93.40 y = -9.7143x 2 + 85.579x 75.864 1.00 τ, pa 251.51 765.83 1008.25 y = -135.95x2 + 922.16x 534.7 1.00 bt1-5 v, cm/s 0 9.30 50.90 y = 16.102x 2 38.962x + 22.86 1.00 τ, pa 212.76 245.83 586.24 y = 153.67x2 427.93x + 487.03 1.00 views of the inclined plane (ip) test method, when for roughening of plywood surface were used membrane and geotextile, are presented in figs 6 (a-c) and figs 7 (a-c). a) α = 25° b) α = 35° c) α = 45° figure 6. view of the inclined plane test method, when for roughening of plywood surface was used membrane from figs 6a and 7a we can see that fresh concrete samples are stable on a sloping plane (when α = 25°) and also didn’t slides down along an inclined plane. figs 6b and 7b show that some part of fresh concrete samples isn’t stable on a sloping plane (when α = 35°) and only unstable part of fresh concrete sample slides down along an inclined plane. figs 6c and 7c show that fresh concrete samples aren’t stable on a sloping plane (when α = 35°) and slides down along an inclined plane. increase and was equal 0, i.e. sliding process of fresh concrete samples on a sloping plane was stopped (table 7). roughening of plywood surface by using membrane and geotextile affects the sliding process of fresh concrete samples. due to dimpled membrane studs, which are approx. 8 mm height, effect on sliding process is bigger compering to geotextile effect on sliding process. table 7. the results of the sliding speed and shear stress of fresh concrete samples with different angle of the plane inclination, when for roughening of plywood surface were used membrane and geotextile mark of concrete mixture composition sliding speed (v) and shear stress (τ) angle of inclination, ° equation correlation coefficient r 25 35 45 for roughening of plywood surface was used membrane bt1-3 v, cm/s 0 0 0 τ, pa 281.10 526.51 760.95 y = -5.4835x2 + 261.85x + 24.732 1.00 bt1-5 v, cm/s 0 0 31.70 y = 15.833x 21.111 1.00 τ, pa 212.76 639.16 977.06 y = -44.253x2 + 559.16x 302.14 0.86 for roughening of plywood surface was used geotextile bt1-3 v, cm/s 0 56.40 93.40 y = -9.7143x 2 + 85.579x 75.864 1.00 τ, pa 251.51 765.83 1008.25 y = -135.95x2 + 922.16x 534.7 1.00 bt1-5 v, cm/s 0 9.30 50.90 y = 16.102x 2 38.962x + 22.86 1.00 τ, pa 212.76 245.83 586.24 y = 153.67x2 427.93x + 487.03 1.00 views of the inclined plane (ip) test method, when for roughening of plywood surface were used membrane and geotextile, are presented in figs 6 (a-c) and figs 7 (a-c). a) α = 25° b) α = 35° c) α = 45° figure 6. view of the inclined plane test method, when for roughening of plywood surface was used membrane from figs 6a and 7a we can see that fresh concrete samples are stable on a sloping plane (when α = 25°) and also didn’t slides down along an inclined plane. figs 6b and 7b show that some part of fresh concrete samples isn’t stable on a sloping plane (when α = 35°) and only unstable part of fresh concrete sample slides down along an inclined plane. figs 6c and 7c show that fresh concrete samples aren’t stable on a sloping plane (when α = 35°) and slides down along an inclined plane. α = 25° α = 25° α = 35° α = 35° α = 45° α = 45° (a) (a) (b) (b) (c) (c) table 8 comparison of the yield stress and shear stress of fresh concrete, when for roughening of plywood surface were used membrane and geotextile a) α = 25° b) α = 35° c) α = 45° figure 7. view of the inclined plane test method, when for roughening of plywood surface was used geotextile table 8. comparison of the yield stress and shear stress of fresh concrete, when for roughening of plywood surface were used membrane and geotextile the mark of concrete mixture proportion τ0, pa τ, pa checking if condition τ0 ≥ τ angle of inclination, ° angle of inclination, ° 25 35 45 25 35 45 for roughening of plywood surface was used membrane bt1-3 416.09 281.10 526.51 760.95 stable not stable not stable bt1-5 207.85 212.76 639.16 977.06 not stable not stable not stable for roughening of plywood surface was used geotextile bt1-3 416.09 251.51 765.83 1008.25 stable not stable not stable bt1-5 207.85 212.76 245.83 586.24 not stable not stable not stable from results given in table 8 we can see that the fresh concrete sample is stable on a sloping plane if its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete. roughening of plywood surface by using membrane and geotextile has an effect on stability of fresh concrete samples, when angle of plane inclination isn’t bigger than 25°. conclusions the test results showed that the increase of coarse aggregate (gravel of fraction 4/16 mm) content from about 417 to 1175 kg in concrete mixture is enough to achieve the stability of fresh concrete sample, when plane inclination angles are 25°, 35° and 45°, but not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. roughening of plywood surface by using special dimpled membrane and geotextile affects the sliding speed of fresh concrete samples, i.e. its stop sliding process of fresh concrete samples. due to used membrane studs, which are approx. 8 mm height, effect on sliding process is bigger compering to geotextile effect on sliding process. performing concrete work of slope-type structures, roughening of used formwork plywood surface by using special dimpled membrane or geotextile could be new decision to stop sliding process of fresh concrete. a) α = 25° b) α = 35° c) α = 45° figure 7. view of the inclined plane test method, when for roughening of plywood surface was used geotextile table 8. comparison of the yield stress and shear stress of fresh concrete, when for roughening of plywood surface were used membrane and geotextile the mark of concrete mixture proportion τ0, pa τ, pa checking if condition τ0 ≥ τ angle of inclination, ° angle of inclination, ° 25 35 45 25 35 45 for roughening of plywood surface was used membrane bt1-3 416.09 281.10 526.51 760.95 stable not stable not stable bt1-5 207.85 212.76 639.16 977.06 not stable not stable not stable for roughening of plywood surface was used geotextile bt1-3 416.09 251.51 765.83 1008.25 stable not stable not stable bt1-5 207.85 212.76 245.83 586.24 not stable not stable not stable from results given in table 8 we can see that the fresh concrete sample is stable on a sloping plane if its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete. roughening of plywood surface by using membrane and geotextile has an effect on stability of fresh concrete samples, when angle of plane inclination isn’t bigger than 25°. conclusions the test results showed that the increase of coarse aggregate (gravel of fraction 4/16 mm) content from about 417 to 1175 kg in concrete mixture is enough to achieve the stability of fresh concrete sample, when plane inclination angles are 25°, 35° and 45°, but not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. roughening of plywood surface by using special dimpled membrane and geotextile affects the sliding speed of fresh concrete samples, i.e. its stop sliding process of fresh concrete samples. due to used membrane studs, which are approx. 8 mm height, effect on sliding process is bigger compering to geotextile effect on sliding process. performing concrete work of slope-type structures, roughening of used formwork plywood surface by using special dimpled membrane or geotextile could be new decision to stop sliding process of fresh concrete. a) α = 25° b) α = 35° c) α = 45° figure 7. view of the inclined plane test method, when for roughening of plywood surface was used geotextile table 8. comparison of the yield stress and shear stress of fresh concrete, when for roughening of plywood surface were used membrane and geotextile the mark of concrete mixture proportion τ0, pa τ, pa checking if condition τ0 ≥ τ angle of inclination, ° angle of inclination, ° 25 35 45 25 35 45 for roughening of plywood surface was used membrane bt1-3 416.09 281.10 526.51 760.95 stable not stable not stable bt1-5 207.85 212.76 639.16 977.06 not stable not stable not stable for roughening of plywood surface was used geotextile bt1-3 416.09 251.51 765.83 1008.25 stable not stable not stable bt1-5 207.85 212.76 245.83 586.24 not stable not stable not stable from results given in table 8 we can see that the fresh concrete sample is stable on a sloping plane if its yield stress τ0 is greater than the shear stress τ, which appears in the fresh concrete. roughening of plywood surface by using membrane and geotextile has an effect on stability of fresh concrete samples, when angle of plane inclination isn’t bigger than 25°. conclusions the test results showed that the increase of coarse aggregate (gravel of fraction 4/16 mm) content from about 417 to 1175 kg in concrete mixture is enough to achieve the stability of fresh concrete sample, when plane inclination angles are 25°, 35° and 45°, but not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. roughening of plywood surface by using special dimpled membrane and geotextile affects the sliding speed of fresh concrete samples, i.e. its stop sliding process of fresh concrete samples. due to used membrane studs, which are approx. 8 mm height, effect on sliding process is bigger compering to geotextile effect on sliding process. performing concrete work of slope-type structures, roughening of used formwork plywood surface by using special dimpled membrane or geotextile could be new decision to stop sliding process of fresh concrete. fig. 7 view of the inclined plane test method, when for roughening of plywood surface was used geotextile the mark of concrete mixture proportion τ0, pa τ, pa checking if condition τ0 ≥ τ angle of inclination, ° angle of inclination, ° 25 35 45 25 35 45 for roughening of plywood surface was used membrane bt1-3 416.09 281.10 526.51 760.95 stable not stable not stable bt1-5 207.85 212.76 639.16 977.06 not stable not stable not stable for roughening of plywood surface was used geotextile bt1-3 416.09 251.51 765.83 1008.25 stable not stable not stable bt1-5 207.85 212.76 245.83 586.24 not stable not stable not stable journal of sustainable architecture and civil engineering 2020/1/26 96 roughening of plywood surface by using membrane and geotextile has an effect on stability of fresh concrete samples, when angle of plane inclination isn’t bigger than 25°. the test results showed that the increase of coarse aggregate (gravel of fraction 4/16 mm) content from about 417 to 1175 kg in concrete mixture is enough to achieve the stability of fresh concrete sample, when plane inclination angles are 25°, 35° and 45°, but not enough to stop sliding process. in this case, additional implements are needed to increase the adhesion of fresh concrete to the base. roughening of plywood surface by using special dimpled membrane and geotextile affects the sliding speed of fresh concrete samples, i.e. its stop sliding process of fresh concrete samples. due to used membrane studs, which are approx. 8 mm height, effect on sliding process is bigger compering to geotextile effect on sliding process. performing concrete work of slope-type structures, roughening of used formwork plywood surface by using special dimpled membrane or geotextile could be new decision to stop sliding process of fresh concrete. conclusions aissoun b.m., hwang s., khayat k.h. influence of aggregate characteristics on workability of superworkable concrete, materials and structures, 2016; 49: 597-609. https://doi.org/10.1617/s11527-0150522-9 assaad j., khayat k.h. influence of internal friction and 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https://doi.org/10.14359/51663972 koehler e.p., fowler d.w. development of a portable rheometer for fresh portland cement concrete, icar report 105-3f, 2004; 103-105. mork j.h., gjorv o.e. effect of gypsum-hemihydrate ratio in cement on rheological properties of fresh concrete, aci material journal, 1997; 94: 142-146. https://doi.org/10.14359/295 santos a.c.p., ortiz-lozano j.a., villegas n., et al. experimental study about the effects of granular skeleton distribution on the mechanical properties of self-compacting concrete (scc), construction and building materials, 2015; 78: 40-49. https://doi. org/10.1016/j.conbuildmat.2015.01.006 skripkiūnas g. optimization of concrete macrostructure according to technological and performance properties and raw material resources, ph.d.-thesis, kaunas university of technology, 1993 (lithuanian). references https://doi.org/10.1617/s11527-015-0522-9 https://doi.org/10.1617/s11527-015-0522-9 https://doi.org/10.1016/j.cemconcomp.2011.09.006 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rheological properties of mortars, cement and concrete composites, 2008; 30: 274-282. https://doi. org/10.1016/j.cemconcomp.2007.08.008 zhang j., xuehui a., ding n. effect of fine aggregate characteristics on the thresholds of self-compacting paste rheological properties. construction and building materials, 2016; 116: 355-365. https://doi. org/10.1016/j.conbuildmat.2016.04.069 žiogas v. a., juočiūnas s., medelienė v., žiogas g. concreting and early hardening processes in monolithic reinforced concrete structures, engineering structures and technologies, 2012; 4: 67-75. https:// doi.org/10.3846/2029882x.2012.699258 rokas kudirka master at faculty of civil engineering and architecture main research area civil engineering. address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: 1rokas@inbox.lt mindaugas daukšys dr. faculty of civil engineering and architecture main research area civil engineering, construction technology. address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: mindaugas.dauksys@ktu.lt svajūnas juočiūnas lecturer faculty of civil engineering and architecture main research area civil engineering, construction technology. address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: svajunas.juociunas@ktu.lt about the authors https://doi.org/10.1016/j.cemconcomp.2007.08.008 https://doi.org/10.1016/j.cemconcomp.2007.08.008 https://doi.org/10.1016/j.conbuildmat.2016.04.069 https://doi.org/10.1016/j.conbuildmat.2016.04.069 https://doi.org/10.3846/2029882x.2012.699258 https://doi.org/10.3846/2029882x.2012.699258 79 journal of sustainable architecture and civil engineering 2018/2/23 *corresponding author: tadaslisauskas@gmail.com the stress’s state analysis of carbon fibre reinforced concrete elements evaluating the bond influence received 2018/05/31 accepted after revision 2018/11/09 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 79-10 doi 10.5755/j01.sace.23.2.20987 the stress’s state analysis of carbon fibre reinforced concrete elements evaluating the bond influence jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.20987 tadas lisauskas, mindaugas augonis, šarūnas kelpša kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania introduction while strengthening structures with thin layered elements an important role is carried out by the bond between separate elements, but there are not any methods which would describe the distribution of bond stress in the contact zone when the concrete behaviour is elastic and plastic. in this article a single span reinforced concrete beam which is strengthened by cfrp (carbon fibre reinforced polymer) is analysed and three methods which could describe bond stress through the length of the element are provided. the three compared methods are: finite elements method (fem), theory of multiple rods and the proposed method of the authors. the similarities and differences of results are shown by diagrams and discussed. the method that the authors propose is superior to other methods because of evaluation of the plastic behaviour of concrete which is not possible to evaluate it by the method of the theory of multiple rods. keywords: bond, cfrp, reinforced concrete, stress, strengthening. nowadays in modern world, when architecture is getting more complex and the structural requirements are growing higher, the strengthening of structures plays an important role. in this article the strengthening of reinforced concrete beam structures with thin layered materials is analysed. the main focus is given to analyse the contact zone between separate layers. many authors analyse the contact zone between fibre and concrete, but these methods separately not evaluate the effect of concrete behaviour in reinforced concrete structures. in this article the analysis of reinforced flexural reinforced concrete structures is made, applying the finite elements method, the theory of multiple rods method and the method proposed by the authors. the experiments show that the highest bond stress in the contact zone was at the front and the back end of the beam. however, when the load is increasing, the bond at the end of a beam is decreasing, so the highest bond stress shifts a little bit further from the end. it happens because at the end of the beam the tension strength of a concrete is exceeded. (guo2005, guo 2007) while analysing a single span beam which is strengthened by cfrp it was received that the shear contact stress increases evenly at the centre of a beam and increases greatly at the ends. (lorenzis 2001) journal of sustainable architecture and civil engineering 2018/2/23 80 the examined composite beams are made of two elements so the interaction between the elements is analysed when there are different bonds in the elastic stage because of a hydrothermal load. to describe the bond between different elements the theory of multiple rods is being used. (zabulionis 2005). methods fig. 2 cross-section of beam fig. 1 test setup table 1 materials parameters ec es ecfrp υc υs υg υcfrp 28 gpa 200 gpa 230 gpa 0,25 0,3 0,3 0,3 where: ec, es, ecfrp – concrete’s, steel’s or carbon fibber’s elasticity module; υc, υs, υg, υcfrp – concrete’s, steel’s, glue’s or carbon fiber’s poisson’s ratio in this article a single span reinforced concrete beam reinforced by carbon fibre is analysed. the test setup and the cross-section of the beam are provided in the figures fig.1 and fig. 2. concrete, steel, carbon fibre and glue material parameters are provided in the table 1. methods in this article a single span reinforced concrete beam reinforced by carbon fibre is analysed. the test setup and the cross-section of the beam are provided in the figures fig.1 and fig. 2. concrete, steel, carbon fibre and glue material parameters are provided in the table 1. table 1. materials parameters ec es ecfrp υc υs υg υcfrp 28 gpa 200 gpa 230 gpa 0,25 0,3 0,3 0,3 where: ec, es, ecfrp – concrete’s, steel’s or carbon fibber’s elasticity module; υc, υs, υg, υcfrp – concrete’s, steel’s, glue’s or carbon fiber’s poisson’s ratio in this article three comparative calculation methods are used: finite elements method, theory of multiple rods method and a method that is created by the authors which is based on iteration method. 1. finite elements method. a three-dimensional calculation model from the provided test setup is made with the “ansys” program. modelling the finite elements model the support point is chosen not at the end, but in the centre of the beam. this kind of scheme helps to avoid stress concentrators which distort the distribution of shear stress at the ends of the beam fig. 3. when creating the test setup and describing the bond between carbon fibre and concrete a layer of 1 mm thickness of glue was chosen. when changing the glue layer elasticity modulus, the bond between the layers changes as well as the values of bond stress. in this article the following glue elasticity modulus was used: 𝐸𝐸� =0,2 gpa; 2,0 gpa; 28,0 gpa. the highest elasticity modulus (28 gpa), which equals to the concrete one, means that the bond between the layers is perfectly good. an elasticity modulus (2,0 gpa) represent the real glue elasticity modulus [rabinovitch 2001, adruini 1997]. smallest elasticity modulus (0,2 gpa) means that the bond between the layers is very poor. if the bond is even more reduced the stress in the concrete and the rebar does not change. in order to describe the concrete solid65 element was used. this element describes the nonlinear behaviour of a concrete. (ansys 2016) 2. theory of multiple rods. the theory of multiple rods was used to describe the behaviour of layered structures when there is a certain bond. the calculation method is used by (ржаницын 1982, ржаницын 1986). in fig. 4 the certain geometrical parameters, bond stress and relative strains distribution in the contact zone are provided. the calculation formulas for the two layered structures are provided below. fig. 2. cross-section of beam fig. 1. test setup fig. 3. distribution of shear stress at the ends of the beam fig. 4. shear stress and relative strains distribution in the contact zone methods in this article a single span reinforced concrete beam reinforced by carbon fibre is analysed. the test setup and the cross-section of the beam are provided in the figures fig.1 and fig. 2. concrete, steel, carbon fibre and glue material parameters are provided in the table 1. table 1. materials parameters ec es ecfrp υc υs υg υcfrp 28 gpa 200 gpa 230 gpa 0,25 0,3 0,3 0,3 where: ec, es, ecfrp – concrete’s, steel’s or carbon fibber’s elasticity module; υc, υs, υg, υcfrp – concrete’s, steel’s, glue’s or carbon fiber’s poisson’s ratio in this article three comparative calculation methods are used: finite elements method, theory of multiple rods method and a method that is created by the authors which is based on iteration method. 1. finite elements method. a three-dimensional calculation model from the provided test setup is made with the “ansys” program. modelling the finite elements model the support point is chosen not at the end, but in the centre of the beam. this kind of scheme helps to avoid stress concentrators which distort the distribution of shear stress at the ends of the beam fig. 3. when creating the test setup and describing the bond between carbon fibre and concrete a layer of 1 mm thickness of glue was chosen. when changing the glue layer elasticity modulus, the bond between the layers changes as well as the values of bond stress. in this article the following glue elasticity modulus was used: 𝐸𝐸� =0,2 gpa; 2,0 gpa; 28,0 gpa. the highest elasticity modulus (28 gpa), which equals to the concrete one, means that the bond between the layers is perfectly good. an elasticity modulus (2,0 gpa) represent the real glue elasticity modulus [rabinovitch 2001, adruini 1997]. smallest elasticity modulus (0,2 gpa) means that the bond between the layers is very poor. if the bond is even more reduced the stress in the concrete and the rebar does not change. in order to describe the concrete solid65 element was used. this element describes the nonlinear behaviour of a concrete. (ansys 2016) 2. theory of multiple rods. the theory of multiple rods was used to describe the behaviour of layered structures when there is a certain bond. the calculation method is used by (ржаницын 1982, ржаницын 1986). in fig. 4 the certain geometrical parameters, bond stress and relative strains distribution in the contact zone are provided. the calculation formulas for the two layered structures are provided below. fig. 2. cross-section of beam fig. 1. test setup fig. 3. distribution of shear stress at the ends of the beam fig. 4. shear stress and relative strains distribution in the contact zone in this article three comparative calculation methods are used: finite elements method, theory of multiple rods method and a method that is created by the authors which is based on iteration method. 1. finite elements method a three-dimensional calculation model from the provided test setup is made with the “ansys” program. modelling the finite elements model the support point is chosen not at the end, but in the centre of the beam. this kind of scheme helps to avoid stress concentrators which distort the distribution of shear stress at the ends of the beam fig. 3. when creating the test setup and describing the bond between carbon fibre and concrete a layer of 1 mm thickness of glue was chosen. when changing the glue layer elasticity modulus, the bond between the layers changes as well as the values of bond stress. in this article the following glue elasticity modulus was used: eg = 0,2 gpa; 2,0 gpa; 28,0 gpa. the highest elasticity modulus (28 gpa), which equals to the concrete one, means that the bond between the layers is perfectly good. an elasticity modulus fig. 3 distribution of shear stress at the ends of the beam methods in this article a single span reinforced concrete beam reinforced by carbon fibre is analysed. the test setup and the cross-section of the beam are provided in the figures fig.1 and fig. 2. concrete, steel, carbon fibre and glue material parameters are provided in the table 1. table 1. materials parameters ec es ecfrp υc υs υg υcfrp 28 gpa 200 gpa 230 gpa 0,25 0,3 0,3 0,3 where: ec, es, ecfrp – concrete’s, steel’s or carbon fibber’s elasticity module; υc, υs, υg, υcfrp – concrete’s, steel’s, glue’s or carbon fiber’s poisson’s ratio in this article three comparative calculation methods are used: finite elements method, theory of multiple rods method and a method that is created by the authors which is based on iteration method. 1. finite elements method. a three-dimensional calculation model from the provided test setup is made with the “ansys” program. modelling the finite elements model the support point is chosen not at the end, but in the centre of the beam. this kind of scheme helps to avoid stress concentrators which distort the distribution of shear stress at the ends of the beam fig. 3. when creating the test setup and describing the bond between carbon fibre and concrete a layer of 1 mm thickness of glue was chosen. when changing the glue layer elasticity modulus, the bond between the layers changes as well as the values of bond stress. in this article the following glue elasticity modulus was used: 𝐸𝐸� =0,2 gpa; 2,0 gpa; 28,0 gpa. the highest elasticity modulus (28 gpa), which equals to the concrete one, means that the bond between the layers is perfectly good. an elasticity modulus (2,0 gpa) represent the real glue elasticity modulus [rabinovitch 2001, adruini 1997]. smallest elasticity modulus (0,2 gpa) means that the bond between the layers is very poor. if the bond is even more reduced the stress in the concrete and the rebar does not change. in order to describe the concrete solid65 element was used. this element describes the nonlinear behaviour of a concrete. (ansys 2016) 2. theory of multiple rods. the theory of multiple rods was used to describe the behaviour of layered structures when there is a certain bond. the calculation method is used by (ржаницын 1982, ржаницын 1986). in fig. 4 the certain geometrical parameters, bond stress and relative strains distribution in the contact zone are provided. the calculation formulas for the two layered structures are provided below. fig. 2. cross-section of beam fig. 1. test setup fig. 3. distribution of shear stress at the ends of the beam fig. 4. shear stress and relative strains distribution in the contact zone (2,0 gpa) represent the real glue elasticity modulus [rabinovitch 2001, adruini 1997]. smallest elasticity modulus (0,2 gpa) means that the bond between the layers is very poor. if the bond is even more reduced the stress in the concrete and the rebar does not change. in order to describe the concrete solid65 element was used. this element describes the nonlinear behaviour of a concrete. (ansys 2016) 1 2 81 journal of sustainable architecture and civil engineering 2018/2/23 2. theory of multiple rods the theory of multiple rods was used to describe the behaviour of layered structures when there is a certain bond. the calculation method is used by (ржаницын 1982, ржаницын 1986). in fig. 4 the certain geometrical parameters, bond stress and relative strains distribution in the contact zone are provided. the calculation formulas for the two layered structures are provided below. fig. 4 shear stress and relative strains distribution in the contact zone fig. 5 dividing of the cross-section in the layers methods in this article a single span reinforced concrete beam reinforced by carbon fibre is analysed. the test setup and the cross-section of the beam are provided in the figures fig.1 and fig. 2. concrete, steel, carbon fibre and glue material parameters are provided in the table 1. table 1. materials parameters ec es ecfrp υc υs υg υcfrp 28 gpa 200 gpa 230 gpa 0,25 0,3 0,3 0,3 where: ec, es, ecfrp – concrete’s, steel’s or carbon fibber’s elasticity module; υc, υs, υg, υcfrp – concrete’s, steel’s, glue’s or carbon fiber’s poisson’s ratio in this article three comparative calculation methods are used: finite elements method, theory of multiple rods method and a method that is created by the authors which is based on iteration method. 1. finite elements method. a three-dimensional calculation model from the provided test setup is made with the “ansys” program. modelling the finite elements model the support point is chosen not at the end, but in the centre of the beam. this kind of scheme helps to avoid stress concentrators which distort the distribution of shear stress at the ends of the beam fig. 3. when creating the test setup and describing the bond between carbon fibre and concrete a layer of 1 mm thickness of glue was chosen. when changing the glue layer elasticity modulus, the bond between the layers changes as well as the values of bond stress. in this article the following glue elasticity modulus was used: 𝐸𝐸� =0,2 gpa; 2,0 gpa; 28,0 gpa. the highest elasticity modulus (28 gpa), which equals to the concrete one, means that the bond between the layers is perfectly good. an elasticity modulus (2,0 gpa) represent the real glue elasticity modulus [rabinovitch 2001, adruini 1997]. smallest elasticity modulus (0,2 gpa) means that the bond between the layers is very poor. if the bond is even more reduced the stress in the concrete and the rebar does not change. in order to describe the concrete solid65 element was used. this element describes the nonlinear behaviour of a concrete. (ansys 2016) 2. theory of multiple rods. the theory of multiple rods was used to describe the behaviour of layered structures when there is a certain bond. the calculation method is used by (ржаницын 1982, ржаницын 1986). in fig. 4 the certain geometrical parameters, bond stress and relative strains distribution in the contact zone are provided. the calculation formulas for the two layered structures are provided below. fig. 2. cross-section of beam fig. 1. test setup fig. 3. distribution of shear stress at the ends of the beam fig. 4. shear stress and relative strains distribution in the contact zone the bond stress of the contact zone through the element length of is calculated by the following equation: the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (1) the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (2) the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (3) the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (4) the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (5) 3. authors proposed calculation method the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element where: e1,2 – elasticity module of layers; a1,2 – cross-section area; ω – distance between centres of layers; med – bending moment; ξ – stiffness of layers joint. is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (6) relative strains, forces and elasticity module matrix: the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (7) the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) journal of sustainable architecture and civil engineering 2018/2/23 82 the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (8) the bond stress of the contact zone through the element length of is calculated by the following equation: τ�𝑥𝑥� = δ ∙ λ ∙ sinh�λ ∙ x� γ ∙ ���h �λ ∙ ��� (1) where: γ = 1𝐸𝐸� ∙ 𝐴𝐴� + 1𝐸𝐸� ∙ 𝐴𝐴� + 𝜔𝜔 � 𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (2) δ = 𝑀𝑀�� ∙ 𝜔𝜔𝐸𝐸� ∙ 𝐴𝐴� + 𝐸𝐸� ∙ 𝐴𝐴� (3) λ = �𝜉𝜉 ∙ γ (4) 𝜉𝜉 = 𝜉𝜉��� ∙ �2,5 − 1,5 ∙ 𝐸𝐸� 𝐸𝐸� � 𝐸𝐸�𝐸𝐸� (5) 𝐸𝐸�,� – elasticity module of layers; 𝐴𝐴�,� – cross-section area; 𝜔𝜔 – distance between centres of layers; 𝑀𝑀�� – bending moment; 𝜉𝜉 – stiffness of layers joint 3. authors proposed calculation method. the base of this proposed calculation method consists of iteration (layers) method (zadlauskas 2013). from the values received using this method the distribution of bond stress through the length of the element is drawn. iteration method is created when the cross-section of the element is divided into the finite numbers of layers fig. 5. every separate layer has its own stiffness and strains. all equations are written into the matrix form: relative strains, forces and elasticity module matrix: 𝜀𝜀 = �𝜀𝜀���� � 𝜀𝜀� 𝜀𝜀� 𝜀𝜀� … 𝜀𝜀� � (7) 𝐹𝐹 = �0 0 0 0 … 𝑀𝑀� (8) �𝐸𝐸� = ⎣ ⎢ ⎢ ⎢ ⎢ ⎡ 1 −2 1 0 … 00 1 −2 1 … 0 0 0 1 −2 … 0 … … … … … 0 𝐸𝐸���� 𝐴𝐴���� 𝑘𝑘���� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� 𝐸𝐸��𝐴𝐴�� … 𝐸𝐸�,� 𝐴𝐴�,� 0 𝐸𝐸��𝐴𝐴��ℎ� 2𝐸𝐸��𝐴𝐴��𝑖𝑖 𝑖𝐸𝐸��𝐴𝐴��ℎ� … 𝑛𝑛𝐸𝐸�,� 𝐴𝐴�,� ℎ� ⎦ ⎥ ⎥ ⎥ ⎥ ⎤ (6) where: 𝑘𝑘���� – coefficient which evaluates the bond between carbon fibre and concrete, 𝐴𝐴� – crosssection area, 𝐸𝐸� – elasticity modulus of layer, ℎ� – height of layer, 𝜀𝜀� – relative strain, 𝑀𝑀 – bending moment. fig. 5. dividing of the cross-section in the layers �𝐸𝐸� ∙ �𝜀𝜀� = �𝐹𝐹� (6) (6) where: kcfrp – coefficient which evaluates the bond between carbon fibre and concrete, ai – cross-section area, ei – elasticity modulus of layer, hi – height of layer, εi – relative strain, m – bending moment. when the first iteration is done the relative strains of every layer are recalculated. if the relative strains exceed the elastic limit of this layer, then the elasticity modulus of this layer is reducing. if the relative strains exceed the ultimate strains, then the strain modulus of this layer is set to 0. sufficiently precise strains are received after calculating a couple of iterations. according to the received strains of layers and the strain modulus it is possible to easily calculate the missing parameters. the results of the analysis are shown in fig. 6 – fig. 9. the maximum bonding coefficient according to the theory of multiple rods is ξmax = 4,69 ∙ 1011 n/m2. this coefficient is received by the method of approximation and accepted as maximal. if this value would be increased the normal stress in the cross-section would remain as constant. according to the results in the diagrams it is seen that the maximum bond stress of the contact zone appears at the ends of the element and it distribute by parabola. further from the end the bond stress decreases significantly and changes according to the line function. analysing the results according to fem the uniqueness at the ends of the beam when the bond is small was noticed. analysis of the shear stress obtained by fem shows that the shear stress becomes decrease at the end of the beam. the maximum value of shear stress is reached not at the end of the structure, but a little bit before it. such a distribution of stress is inresults fig. 6 shear stress through the length of the element when the bond between the elements is small (eg=0,2 gpa) fig. 7 shear stress through the length of the element when the bond between the elements is medium (eg=2,0 gpa) when the first iteration is done the relative strains of every layer are recalculated. if the relative strains exceed the elastic limit of this layer, then the elasticity modulus of this layer is reducing. if the relative strains exceed the ultimate strains, then the strain modulus of this layer is set to 0. sufficiently precise strains are received after calculating a couple of iterations. according to the received strains of layers and the strain modulus it is possible to easily calculate the missing parameters. results the results of the analysis are shown in fig. 6 – fig. 9. the maximum bonding coefficient according to the theory of multiple rods is 𝜉𝜉��� = 4,69 ∙ 10�� 𝑁𝑁𝑁𝑁𝑁�. this coefficient is received by the method of approximation and accepted as maximal. if this value would be increased the normal stress in the crosssection would remain as constant. according to the results in the diagrams it is seen that the maximum bond stress of the contact zone appears at the ends of the element and it distribute by parabola. further from the end the bond stress decreases significantly and changes according to the line function. analysing the results according to fem the uniqueness at the ends of the beam when the bond is small was noticed. analysis of the shear stress obtained by fem shows that the shear stress becomes decrease at the end of the beam. the maximum value of shear stress is reached not at the end of the structure, but a little bit before it. such a distribution of stress is inherent when the concrete reaches the marginal shear stress (gou 2005, gou 2007). according to the proposed method there is not obtained the decrease of stress. in the fig.9 the presented shear stress level is higher because of bigger bending moment that was assumed for the elastic plastic analysis. in fig. 6-8 the normal stress in concrete are under elastic zone. fig. 6. shear stress through the length of the element when the bond between the elements is small (eg=0,2 gpa) fig. 7. shear stress through the length of the element when the bond between the elements is medium (eg=2,0 gpa) -60 -40 -20 0 20 40 60 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m theory of multiple rods fem proposed method -200 -150 -100 -50 0 50 100 150 200 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m theory of multiple rods fem proposed method when the first iteration is done the relative strains of every layer are recalculated. if the relative strains exceed the elastic limit of this layer, then the elasticity modulus of this layer is reducing. if the relative strains exceed the ultimate strains, then the strain modulus of this layer is set to 0. sufficiently precise strains are received after calculating a couple of iterations. according to the received strains of layers and the strain modulus it is possible to easily calculate the missing parameters. results the results of the analysis are shown in fig. 6 – fig. 9. the maximum bonding coefficient according to the theory of multiple rods is 𝜉𝜉��� = 4,69 ∙ 10�� 𝑁𝑁𝑁𝑁𝑁�. this coefficient is received by the method of approximation and accepted as maximal. if this value would be increased the normal stress in the crosssection would remain as constant. according to the results in the diagrams it is seen that the maximum bond stress of the contact zone appears at the ends of the element and it distribute by parabola. further from the end the bond stress decreases significantly and changes according to the line function. analysing the results according to fem the uniqueness at the ends of the beam when the bond is small was noticed. analysis of the shear stress obtained by fem shows that the shear stress becomes decrease at the end of the beam. the maximum value of shear stress is reached not at the end of the structure, but a little bit before it. such a distribution of stress is inherent when the concrete reaches the marginal shear stress (gou 2005, gou 2007). according to the proposed method there is not obtained the decrease of stress. in the fig.9 the presented shear stress level is higher because of bigger bending moment that was assumed for the elastic plastic analysis. in fig. 6-8 the normal stress in concrete are under elastic zone. fig. 6. shear stress through the length of the element when the bond between the elements is small (eg=0,2 gpa) fig. 7. shear stress through the length of the element when the bond between the elements is medium (eg=2,0 gpa) -60 -40 -20 0 20 40 60 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m theory of multiple rods fem proposed method -200 -150 -100 -50 0 50 100 150 200 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m theory of multiple rods fem proposed method 83 journal of sustainable architecture and civil engineering 2018/2/23 fig. 8 shear stress through the length of the element when the bond between the elements is perfect (eg=28 gpa) fig. 9 shear stress through the length of the element when the bond between the stress is medium (eg=2,0 gpa) (plastic behaviour of concrete is evaluated) fig. 8. shear stress through the length of the element when the bond between the elements is perfect (eg=28 gpa) fig. 9. shear stress through the length of the element when the bond between the stress is medium (eg=2,0 gpa) (plastic behaviour of concrete is evaluated) in table 2 the maximum shear stress of a contact zone is provided. they were calculated by different methods evaluating various bonds. one case of calculation was chosen in order to evaluate the plastic behaviour of a concrete. in order to reach the plastic behaviour of a concrete it was needed to increase the bending moment of a beam 𝑀𝑀�� = 1,89 𝑘𝑘𝑘𝑘𝑘𝑘. the tension strength of a concrete 𝑓𝑓�� = 1,5 𝑀𝑀𝑀𝑀𝑀𝑀. it was accepted that the concrete strain modulus is varying linearly from the highest to zero (when a crack appears). this change is described in formulas (7, 8). also, in this table the maximum deviation values of authors proposed method from fem or the theory of multiple rods are provided. the maximum difference of authors proposed method did not exceed 5,9 %. maximum relative strains when the concrete is in elastic stage: 𝜀𝜀��,�� = 0,4 ∙ 𝑓𝑓�� 𝐸𝐸� (7) maximum relative strains before the crack appears: 𝜀𝜀��,��� = 2 ∙ 𝑓𝑓�� 𝐸𝐸� (8) table 2. maximum shear stress 𝝉𝝉𝑭𝑭𝑭𝑭𝑭𝑭, pa 𝝉𝝉𝑻𝑻𝑭𝑭𝑻𝑻, pa 𝝉𝝉𝑷𝑷𝑭𝑭, pa max difference, % poor bond 4,89 ∙ 10� 5,07 ∙ 10� 5,00 ∙ 10� 2,16 medium bond 1,64 ∙ 10� 1,57 ∙ 10� 1,55 ∙ 10� 5,90 perfect bond 3,80 ∙ 10� 3,80 ∙ 10� 3,76 ∙ 10� 1,01 medium bond (plastic behaviour of concrete is evaluated) 5,73 ∙ 10 � − 5,69 ∙ 10� 0,71 according to the results obtained by finite elements method and the theory of multiple rods method, the formulas to calculate the shear stress through the element length were derived. coefficient evaluating the bond between the concrete and the carbon fibre: -400 -300 -200 -100 0 100 200 300 400 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m theory of multiple rods fem proposed method -600 -400 -200 0 200 400 600 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m fem proposed method fig. 8. shear stress through the length of the element when the bond between the elements is perfect (eg=28 gpa) fig. 9. shear stress through the length of the element when the bond between the stress is medium (eg=2,0 gpa) (plastic behaviour of concrete is evaluated) in table 2 the maximum shear stress of a contact zone is provided. they were calculated by different methods evaluating various bonds. one case of calculation was chosen in order to evaluate the plastic behaviour of a concrete. in order to reach the plastic behaviour of a concrete it was needed to increase the bending moment of a beam 𝑀𝑀�� = 1,89 𝑘𝑘𝑘𝑘𝑘𝑘. the tension strength of a concrete 𝑓𝑓�� = 1,5 𝑀𝑀𝑀𝑀𝑀𝑀. it was accepted that the concrete strain modulus is varying linearly from the highest to zero (when a crack appears). this change is described in formulas (7, 8). also, in this table the maximum deviation values of authors proposed method from fem or the theory of multiple rods are provided. the maximum difference of authors proposed method did not exceed 5,9 %. maximum relative strains when the concrete is in elastic stage: 𝜀𝜀��,�� = 0,4 ∙ 𝑓𝑓�� 𝐸𝐸� (7) maximum relative strains before the crack appears: 𝜀𝜀��,��� = 2 ∙ 𝑓𝑓�� 𝐸𝐸� (8) table 2. maximum shear stress 𝝉𝝉𝑭𝑭𝑭𝑭𝑭𝑭, pa 𝝉𝝉𝑻𝑻𝑭𝑭𝑻𝑻, pa 𝝉𝝉𝑷𝑷𝑭𝑭, pa max difference, % poor bond 4,89 ∙ 10� 5,07 ∙ 10� 5,00 ∙ 10� 2,16 medium bond 1,64 ∙ 10� 1,57 ∙ 10� 1,55 ∙ 10� 5,90 perfect bond 3,80 ∙ 10� 3,80 ∙ 10� 3,76 ∙ 10� 1,01 medium bond (plastic behaviour of concrete is evaluated) 5,73 ∙ 10 � − 5,69 ∙ 10� 0,71 according to the results obtained by finite elements method and the theory of multiple rods method, the formulas to calculate the shear stress through the element length were derived. coefficient evaluating the bond between the concrete and the carbon fibre: -400 -300 -200 -100 0 100 200 300 400 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m theory of multiple rods fem proposed method -600 -400 -200 0 200 400 600 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m fem proposed method herent when the concrete reaches the marginal shear stress (gou 2005, gou 2007). according to the proposed method there is not obtained the decrease of stress. in the fig.9 the presented shear stress level is higher because of bigger bending moment that was assumed for the elastic plastic analysis. in fig. 6-8 the normal stress in concrete are under elastic zone. in table 2 the maximum shear stress of a contact zone is provided. they were calculated by different methods evaluating various bonds. one case of calculation was chosen in order to evaluate the plastic behaviour of a concrete. in order to reach the plastic behaviour of a concrete it was needed to increase the bending moment of a beam. the tension strength of a concrete . it was accepted that the concrete strain modulus is varying linearly from the highest to zero (when a crack appears). this change is described in formulas (7, 8). also, in this table the maximum deviation values of authors proposed method from fem or the theory of multiple rods are provided. the maximum difference of authors proposed method did not exceed 5,9 %. maximum relative strains when the concrete is in elastic stage: fig. 8. shear stress through the length of the element when the bond between the elements is perfect (eg=28 gpa) fig. 9. shear stress through the length of the element when the bond between the stress is medium (eg=2,0 gpa) (plastic behaviour of concrete is evaluated) in table 2 the maximum shear stress of a contact zone is provided. they were calculated by different methods evaluating various bonds. one case of calculation was chosen in order to evaluate the plastic behaviour of a concrete. in order to reach the plastic behaviour of a concrete it was needed to increase the bending moment of a beam 𝑀𝑀�� = 1,89 𝑘𝑘𝑘𝑘𝑘𝑘. the tension strength of a concrete 𝑓𝑓�� = 1,5 𝑀𝑀𝑀𝑀𝑀𝑀. it was accepted that the concrete strain modulus is varying linearly from the highest to zero (when a crack appears). this change is described in formulas (7, 8). also, in this table the maximum deviation values of authors proposed method from fem or the theory of multiple rods are provided. the maximum difference of authors proposed method did not exceed 5,9 %. maximum relative strains when the concrete is in elastic stage: 𝜀𝜀��,�� = 0,4 ∙ 𝑓𝑓�� 𝐸𝐸� (7) maximum relative strains before the crack appears: 𝜀𝜀��,��� = 2 ∙ 𝑓𝑓�� 𝐸𝐸� (8) table 2. maximum shear stress 𝝉𝝉𝑭𝑭𝑭𝑭𝑭𝑭, pa 𝝉𝝉𝑻𝑻𝑭𝑭𝑻𝑻, pa 𝝉𝝉𝑷𝑷𝑭𝑭, pa max difference, % poor bond 4,89 ∙ 10� 5,07 ∙ 10� 5,00 ∙ 10� 2,16 medium bond 1,64 ∙ 10� 1,57 ∙ 10� 1,55 ∙ 10� 5,90 perfect bond 3,80 ∙ 10� 3,80 ∙ 10� 3,76 ∙ 10� 1,01 medium bond (plastic behaviour of concrete is evaluated) 5,73 ∙ 10 � − 5,69 ∙ 10� 0,71 according to the results obtained by finite elements method and the theory of multiple rods method, the formulas to calculate the shear stress through the element length were derived. coefficient evaluating the bond between the concrete and the carbon fibre: -400 -300 -200 -100 0 100 200 300 400 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m theory of multiple rods fem proposed method -600 -400 -200 0 200 400 600 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m fem proposed method (7) maximum relative strains before the crack appears: fig. 8. shear stress through the length of the element when the bond between the elements is perfect (eg=28 gpa) fig. 9. shear stress through the length of the element when the bond between the stress is medium (eg=2,0 gpa) (plastic behaviour of concrete is evaluated) in table 2 the maximum shear stress of a contact zone is provided. they were calculated by different methods evaluating various bonds. one case of calculation was chosen in order to evaluate the plastic behaviour of a concrete. in order to reach the plastic behaviour of a concrete it was needed to increase the bending moment of a beam 𝑀𝑀�� = 1,89 𝑘𝑘𝑘𝑘𝑘𝑘. the tension strength of a concrete 𝑓𝑓�� = 1,5 𝑀𝑀𝑀𝑀𝑀𝑀. it was accepted that the concrete strain modulus is varying linearly from the highest to zero (when a crack appears). this change is described in formulas (7, 8). also, in this table the maximum deviation values of authors proposed method from fem or the theory of multiple rods are provided. the maximum difference of authors proposed method did not exceed 5,9 %. maximum relative strains when the concrete is in elastic stage: 𝜀𝜀��,�� = 0,4 ∙ 𝑓𝑓�� 𝐸𝐸� (7) maximum relative strains before the crack appears: 𝜀𝜀��,��� = 2 ∙ 𝑓𝑓�� 𝐸𝐸� (8) table 2. maximum shear stress 𝝉𝝉𝑭𝑭𝑭𝑭𝑭𝑭, pa 𝝉𝝉𝑻𝑻𝑭𝑭𝑻𝑻, pa 𝝉𝝉𝑷𝑷𝑭𝑭, pa max difference, % poor bond 4,89 ∙ 10� 5,07 ∙ 10� 5,00 ∙ 10� 2,16 medium bond 1,64 ∙ 10� 1,57 ∙ 10� 1,55 ∙ 10� 5,90 perfect bond 3,80 ∙ 10� 3,80 ∙ 10� 3,76 ∙ 10� 1,01 medium bond (plastic behaviour of concrete is evaluated) 5,73 ∙ 10 � − 5,69 ∙ 10� 0,71 according to the results obtained by finite elements method and the theory of multiple rods method, the formulas to calculate the shear stress through the element length were derived. coefficient evaluating the bond between the concrete and the carbon fibre: -400 -300 -200 -100 0 100 200 300 400 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m theory of multiple rods fem proposed method -600 -400 -200 0 200 400 600 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 sh ea r s re ss , k pa distance from centre of beam, m fem proposed method (8) according to the results obtained by finite elements method and the theory of multiple rods method, the formulas to calculate the table 2 maximum shear stress τfem, pa τtmr, pa τpm, pa max difference, % poor bond 4,89 ∙ 104 5,07 ∙ 104 5,00 ∙ 104 2,16 medium bond 1,64 ∙105 1,57 ∙ 105 1,55 ∙ 105 5,90 perfect bond 3,80 ∙ 105 3,80 ∙ 105 3,76 ∙ 105 1,01 medium bond (plastic behaviour of concrete is evaluated) 5,73 ∙ 105 5,69 ∙ 105 0,71 journal of sustainable architecture and civil engineering 2018/2/23 84 shear stress through the element length were derived. coefficient evaluating the bond between the concrete and the carbon fibre: 𝑘𝑘���� = � 𝜉𝜉 𝜉𝜉��� � (9) analysing the bond between the concrete and the carbon fibre it was noticed that the maximum shear stress are received at the ends of structures and directly depends on normal stress of the fibre: 𝜏𝜏��� = 𝑘𝑘���� + 0,33 10 ∙ 𝑘𝑘���� ∙ 𝜀𝜀���� ∙ 𝐸𝐸���� (10) shear stress at the ends of an element are distributed by a principle of parabola and could be calculated by the following formulas: 𝜏𝜏 = 𝜏𝜏 ∙ 𝜏𝜏� + 𝑏𝑏 ∙ 𝜏𝜏 (11) 𝜏𝜏 = 𝜏𝜏��� ���� � − �� ∙ 𝜏𝜏� (12) 𝑏𝑏 = −𝜏𝜏 ∙ 𝜏𝜏� (13) 𝜏𝜏� = 𝐿𝐿 2 ∙ 0,9 − 0,02 𝑘𝑘���� (14) distance from the end of element where the parabola equation of shear stress is valid: 𝑙𝑙� = 0,9 ∙ � 𝐿𝐿 2 − 𝜏𝜏��, 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑙𝑙� ≥ 0 (15) discussion the analysis was made for simple supported beam 1 fig. loaded by bending moment at the ends. for different loading cases (if the form of moments diagram change) the additional analysis has to be made and the proposed formulas have to be checked additionally. the plastic behaviour of concrete was evaluated by the proposed method and the fem but not by the theory of multiple rods conclusions 1. the difference of values of shear stress using the proposed method did not exceed 5,9 % compared to fem and the theory of multiple rods. 2. maximum shear stress of contact zone obtained at the ends of a beam or close to it. 3. the shear stress in contact zone at the ends of a beam, according to the proposed method, distributes by a parabola function. 4. authors proposed method is possible to be used for calculation of the reinforced concrete structures strengthened by carbon fibre at the elastic plastic stress stage of concrete. acknowledgment the authors thank to justinas valeika for helping on english. (9) analysing the bond between the concrete and the carbon fibre it was noticed that the maximum shear stress are received at the ends of structures and directly depends on normal stress of the fibre:] 𝑘𝑘���� = � 𝜉𝜉 𝜉𝜉��� � (9) analysing the bond between the concrete and the carbon fibre it was noticed that the maximum shear stress are received at the ends of structures and directly depends on normal stress of the fibre: 𝜏𝜏��� = 𝑘𝑘���� + 0,33 10 ∙ 𝑘𝑘���� ∙ 𝜀𝜀���� ∙ 𝐸𝐸���� (10) shear stress at the ends of an element are distributed by a principle of parabola and could be calculated by the following formulas: 𝜏𝜏 = 𝜏𝜏 ∙ 𝜏𝜏� + 𝑏𝑏 ∙ 𝜏𝜏 (11) 𝜏𝜏 = 𝜏𝜏��� ���� � − �� ∙ 𝜏𝜏� (12) 𝑏𝑏 = −𝜏𝜏 ∙ 𝜏𝜏� (13) 𝜏𝜏� = 𝐿𝐿 2 ∙ 0,9 − 0,02 𝑘𝑘���� (14) distance from the end of element where the parabola equation of shear stress is valid: 𝑙𝑙� = 0,9 ∙ � 𝐿𝐿 2 − 𝜏𝜏��, 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑙𝑙� ≥ 0 (15) discussion the analysis was made for simple supported beam 1 fig. loaded by bending moment at the ends. for different loading cases (if the form of moments diagram change) the additional analysis has to be made and the proposed formulas have to be checked additionally. the plastic behaviour of concrete was evaluated by the proposed method and the fem but not by the theory of multiple rods conclusions 1. the difference of values of shear stress using the proposed method did not exceed 5,9 % compared to fem and the theory of multiple rods. 2. maximum shear stress of contact zone obtained at the ends of a beam or close to it. 3. the shear stress in contact zone at the ends of a beam, according to the proposed method, distributes by a parabola function. 4. authors proposed method is possible to be used for calculation of the reinforced concrete structures strengthened by carbon fibre at the elastic plastic stress stage of concrete. acknowledgment the authors thank to justinas valeika for helping on english. (10) shear stress at the ends of an element are distributed by a principle of parabola and could be calculated by the following formulas: 𝑘𝑘���� = � 𝜉𝜉 𝜉𝜉��� � (9) analysing the bond between the concrete and the carbon fibre it was noticed that the maximum shear stress are received at the ends of structures and directly depends on normal stress of the fibre: 𝜏𝜏��� = 𝑘𝑘���� + 0,33 10 ∙ 𝑘𝑘���� ∙ 𝜀𝜀���� ∙ 𝐸𝐸���� (10) shear stress at the ends of an element are distributed by a principle of parabola and could be calculated by the following formulas: 𝜏𝜏 = 𝜏𝜏 ∙ 𝜏𝜏� + 𝑏𝑏 ∙ 𝜏𝜏 (11) 𝜏𝜏 = 𝜏𝜏��� ���� � − �� ∙ 𝜏𝜏� (12) 𝑏𝑏 = −𝜏𝜏 ∙ 𝜏𝜏� (13) 𝜏𝜏� = 𝐿𝐿 2 ∙ 0,9 − 0,02 𝑘𝑘���� (14) distance from the end of element where the parabola equation of shear stress is valid: 𝑙𝑙� = 0,9 ∙ � 𝐿𝐿 2 − 𝜏𝜏��, 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑙𝑙� ≥ 0 (15) discussion the analysis was made for simple supported beam 1 fig. loaded by bending moment at the ends. for different loading cases (if the form of moments diagram change) the additional analysis has to be made and the proposed formulas have to be checked additionally. the plastic behaviour of concrete was evaluated by the proposed method and the fem but not by the theory of multiple rods conclusions 1. the difference of values of shear stress using the proposed method did not exceed 5,9 % compared to fem and the theory of multiple rods. 2. maximum shear stress of contact zone obtained at the ends of a beam or close to it. 3. the shear stress in contact zone at the ends of a beam, according to the proposed method, distributes by a parabola function. 4. authors proposed method is possible to be used for calculation of the reinforced concrete structures strengthened by carbon fibre at the elastic plastic stress stage of concrete. acknowledgment the authors thank to justinas valeika for helping on english. (11) 𝑘𝑘���� = � 𝜉𝜉 𝜉𝜉��� � (9) analysing the bond between the concrete and the carbon fibre it was noticed that the maximum shear stress are received at the ends of structures and directly depends on normal stress of the fibre: 𝜏𝜏��� = 𝑘𝑘���� + 0,33 10 ∙ 𝑘𝑘���� ∙ 𝜀𝜀���� ∙ 𝐸𝐸���� (10) shear stress at the ends of an element are distributed by a principle of parabola and could be calculated by the following formulas: 𝜏𝜏 = 𝜏𝜏 ∙ 𝜏𝜏� + 𝑏𝑏 ∙ 𝜏𝜏 (11) 𝜏𝜏 = 𝜏𝜏��� ���� � − �� ∙ 𝜏𝜏� (12) 𝑏𝑏 = −𝜏𝜏 ∙ 𝜏𝜏� (13) 𝜏𝜏� = 𝐿𝐿 2 ∙ 0,9 − 0,02 𝑘𝑘���� (14) distance from the end of element where the parabola equation of shear stress is valid: 𝑙𝑙� = 0,9 ∙ � 𝐿𝐿 2 − 𝜏𝜏��, 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑙𝑙� ≥ 0 (15) discussion the analysis was made for simple supported beam 1 fig. loaded by bending moment at the ends. for different loading cases (if the form of moments diagram change) the additional analysis has to be made and the proposed formulas have to be checked additionally. the plastic behaviour of concrete was evaluated by the proposed method and the fem but not by the theory of multiple rods conclusions 1. the difference of values of shear stress using the proposed method did not exceed 5,9 % compared to fem and the theory of multiple rods. 2. maximum shear stress of contact zone obtained at the ends of a beam or close to it. 3. the shear stress in contact zone at the ends of a beam, according to the proposed method, distributes by a parabola function. 4. authors proposed method is possible to be used for calculation of the reinforced concrete structures strengthened by carbon fibre at the elastic plastic stress stage of concrete. acknowledgment the authors thank to justinas valeika for helping on english. (12) 𝑘𝑘���� = � 𝜉𝜉 𝜉𝜉��� � (9) analysing the bond between the concrete and the carbon fibre it was noticed that the maximum shear stress are received at the ends of structures and directly depends on normal stress of the fibre: 𝜏𝜏��� = 𝑘𝑘���� + 0,33 10 ∙ 𝑘𝑘���� ∙ 𝜀𝜀���� ∙ 𝐸𝐸���� (10) shear stress at the ends of an element are distributed by a principle of parabola and could be calculated by the following formulas: 𝜏𝜏 = 𝜏𝜏 ∙ 𝜏𝜏� + 𝑏𝑏 ∙ 𝜏𝜏 (11) 𝜏𝜏 = 𝜏𝜏��� ���� � − �� ∙ 𝜏𝜏� (12) 𝑏𝑏 = −𝜏𝜏 ∙ 𝜏𝜏� (13) 𝜏𝜏� = 𝐿𝐿 2 ∙ 0,9 − 0,02 𝑘𝑘���� (14) distance from the end of element where the parabola equation of shear stress is valid: 𝑙𝑙� = 0,9 ∙ � 𝐿𝐿 2 − 𝜏𝜏��, 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑙𝑙� ≥ 0 (15) discussion the analysis was made for simple supported beam 1 fig. loaded by bending moment at the ends. for different loading cases (if the form of moments diagram change) the additional analysis has to be made and the proposed formulas have to be checked additionally. the plastic behaviour of concrete was evaluated by the proposed method and the fem but not by the theory of multiple rods conclusions 1. the difference of values of shear stress using the proposed method did not exceed 5,9 % compared to fem and the theory of multiple rods. 2. maximum shear stress of contact zone obtained at the ends of a beam or close to it. 3. the shear stress in contact zone at the ends of a beam, according to the proposed method, distributes by a parabola function. 4. authors proposed method is possible to be used for calculation of the reinforced concrete structures strengthened by carbon fibre at the elastic plastic stress stage of concrete. acknowledgment the authors thank to justinas valeika for helping on english. (13) 𝑘𝑘���� = � 𝜉𝜉 𝜉𝜉��� � (9) analysing the bond between the concrete and the carbon fibre it was noticed that the maximum shear stress are received at the ends of structures and directly depends on normal stress of the fibre: 𝜏𝜏��� = 𝑘𝑘���� + 0,33 10 ∙ 𝑘𝑘���� ∙ 𝜀𝜀���� ∙ 𝐸𝐸���� (10) shear stress at the ends of an element are distributed by a principle of parabola and could be calculated by the following formulas: 𝜏𝜏 = 𝜏𝜏 ∙ 𝜏𝜏� + 𝑏𝑏 ∙ 𝜏𝜏 (11) 𝜏𝜏 = 𝜏𝜏��� ���� � − �� ∙ 𝜏𝜏� (12) 𝑏𝑏 = −𝜏𝜏 ∙ 𝜏𝜏� (13) 𝜏𝜏� = 𝐿𝐿 2 ∙ 0,9 − 0,02 𝑘𝑘���� (14) distance from the end of element where the parabola equation of shear stress is valid: 𝑙𝑙� = 0,9 ∙ � 𝐿𝐿 2 − 𝜏𝜏��, 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑙𝑙� ≥ 0 (15) discussion the analysis was made for simple supported beam 1 fig. loaded by bending moment at the ends. for different loading cases (if the form of moments diagram change) the additional analysis has to be made and the proposed formulas have to be checked additionally. the plastic behaviour of concrete was evaluated by the proposed method and the fem but not by the theory of multiple rods conclusions 1. the difference of values of shear stress using the proposed method did not exceed 5,9 % compared to fem and the theory of multiple rods. 2. maximum shear stress of contact zone obtained at the ends of a beam or close to it. 3. the shear stress in contact zone at the ends of a beam, according to the proposed method, distributes by a parabola function. 4. authors proposed method is possible to be used for calculation of the reinforced concrete structures strengthened by carbon fibre at the elastic plastic stress stage of concrete. acknowledgment the authors thank to justinas valeika for helping on english. (14) distance from the end of element where the parabola equation of shear stress is valid: 𝑘𝑘���� = � 𝜉𝜉 𝜉𝜉��� � (9) analysing the bond between the concrete and the carbon fibre it was noticed that the maximum shear stress are received at the ends of structures and directly depends on normal stress of the fibre: 𝜏𝜏��� = 𝑘𝑘���� + 0,33 10 ∙ 𝑘𝑘���� ∙ 𝜀𝜀���� ∙ 𝐸𝐸���� (10) shear stress at the ends of an element are distributed by a principle of parabola and could be calculated by the following formulas: 𝜏𝜏 = 𝜏𝜏 ∙ 𝜏𝜏� + 𝑏𝑏 ∙ 𝜏𝜏 (11) 𝜏𝜏 = 𝜏𝜏��� ���� � − �� ∙ 𝜏𝜏� (12) 𝑏𝑏 = −𝜏𝜏 ∙ 𝜏𝜏� (13) 𝜏𝜏� = 𝐿𝐿 2 ∙ 0,9 − 0,02 𝑘𝑘���� (14) distance from the end of element where the parabola equation of shear stress is valid: 𝑙𝑙� = 0,9 ∙ � 𝐿𝐿 2 − 𝜏𝜏��, 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑙𝑙� ≥ 0 (15) discussion the analysis was made for simple supported beam 1 fig. loaded by bending moment at the ends. for different loading cases (if the form of moments diagram change) the additional analysis has to be made and the proposed formulas have to be checked additionally. the plastic behaviour of concrete was evaluated by the proposed method and the fem but not by the theory of multiple rods conclusions 1. the difference of values of shear stress using the proposed method did not exceed 5,9 % compared to fem and the theory of multiple rods. 2. maximum shear stress of contact zone obtained at the ends of a beam or close to it. 3. the shear stress in contact zone at the ends of a beam, according to the proposed method, distributes by a parabola function. 4. authors proposed method is possible to be used for calculation of the reinforced concrete structures strengthened by carbon fibre at the elastic plastic stress stage of concrete. acknowledgment the authors thank to justinas valeika for helping on english. (15) discussion conclusions the analysis was made for simple supported beam fig. 1 loaded by bending moment at the ends. for different loading cases (if the form of moments diagram change) the additional analysis has to be made and the proposed formulas have to be checked additionally. the plastic behaviour of concrete was evaluated by the proposed method and the fem but not by the theory of multiple rods 1 the difference of values of shear stress using the proposed method did not exceed 5,9 % compared to fem and the theory of multiple rods. 2 maximum shear stress of contact zone obtained at the ends of a beam or close to it. 3 the shear stress in contact zone at the ends of a beam, according to the proposed method, distributes by a parabola function. 4 authors proposed method is possible to be used for calculation of the reinforced concrete structures strengthened by carbon fibre at the elastic plastic stress stage of concrete. acknowledgment the authors thank to justinas valeika for helping on english. 85 journal of sustainable architecture and civil engineering 2018/2/23 guo z.g., cao s.y., sun w.m., lin x.y. experimental study on bond stress-slip behaviour between frp sheets and concrete. proceedings of international symposium on bond behaviour of frp in structures. 2005;(bbfs):77-84. guod. j. interfacial models for fiber reinforced polymer (frp) sheets externally bonded to concrete. michigan state university, 2007. lorenzis d., miller b., nanni a. bond of frp laminates to concrete.aci materials journal, 2001;98(3):256-264. zabulionis d. stress and strain analysis of a bilayer composite beam with interlayer slip under hygrothermal loads. mechanika, 2005;6(6):5-12. the program “ansys”. mechanical apdl17.0. 2016. rabinovitch o., frostig y. nonlinear high-order analreferences ysis of cracked rc beams strengthened with frp strips. journal of structural engineering. 2001; 127 (april): 381-389. adruini m., nanni a. behavior of precracked rc beams strengthened with carbon frp sheets. journal of composites for construction.1997; may: 63-70. ржаницын, a. р. составныестержни и пластинки [composite of rods and plates]. стройиздат. 1986, 316. ржаницын, a. р. строительнаямеханика [structural mechanics]. высшаяшкола. 1982, 396. zadlauskas s. gelžbetoninių tiltų pleišėjimo ir deformacijų nuo statinių ir dinaminių apkrovų tyrimai [the reserarch on cracking and deformation of reinforced concrete bridges under static and dynamic loads]. doctoral dissertation, kauans; 2013; 113 p. tadas lisauskas phd student kaunas university of technology, faculty of civil engineering and architecture, department of civil engineering and architecture competences center main research area frp strengthened reinforced concrete structures address studentu st. 48, lt-51367 kaunas, lithuania tel. 8-610-29-841 e-mail: tadaslisauskas@gmail. com mindaugas augonis assoc. prof kaunas university of technology, faculty of civil engineering and architecture, department of civil engineering and architecture competences center main research area durability of engineering structures, strength and stability or reinforced concrete address studentu st. 48, lt-51367 kaunas, lithuania šarūnas kelpša lecturer kaunas university of technology, faculty of civil engineering and architecture, department of civil engineering and architecture competences center main research area behaviour and analysis of reinforced concrete, steel and composite structures address studentu st. 48, lt-51367 kaunas, lithuania about the authors journal of sustainable architecture and civil engineering 2016/1/14 60 journal of sustainable architecture and civil engineering vol. 1/ no. 14 / 2016 pp. 60-72 doi 10.5755/j01.sace.14.1.15821 © kaunas university of technology received 2016/03/24 accepted after revision 2016/05/31 evaluation of base ground stiffness on statically indeterminate framed building structures jsace 1/14 evaluation of base ground stiffness on statically indeterminate framed building structures *corresponding author: naxo.villalon@gmail.com http://dx.doi.org/10.5755/j01.sace.14.1.15821 introduction ignacio villalon*, deividas martinavičius, mindaugas gricius, šarūnas kelpša department of building structures, faculty of civil engineering and architecture kaunas university of technology, studentu st. 48, lt-51367 kaunas, lithuania mindaugas kasiulevičius jsc “smailusis skliautas”, piliakalnio st. 3, lt-46224 kaunas, lithuania the aim of this paper is to investigate the influence of the modulus of subgrade reaction in statically indeterminate framed structures. in building’s design the interaction between ground and foundation can be modelled variously: using springs instead of supports, modelling the wholesale soil as finite elements, etc. the most common situation in practice is that the interaction is modelled using the springs. nevertheless, there is not just one approved method to calculate it, and engineers use different methods, proposed by various authors. in practice the settlements of foundations are usually calculated and compared with the limit value. however, in some cases the impact of settlements is not taken into account on the analysis of the structure. during the design process, the number of boreholes is always limited. therefore, the real situation cannot be considered exactly. as a result, unforeseen settlements may cause the considerable redistribution of internal forces, leading to the cracking or even to the failure of the structure. in this research, different calculation methods of modulus of subgrade reaction are presented. most of these methods are adopted for the base of foundations consisted of one soil layer. therefore, an evaluation proposal of the modulus of subgrade reaction for multi-layered soils, using the reviewed methods, is suggested. using those methods, the modulus of subgrade reaction of soils of 4 specific boreholes were calculated and compared. furthermore, internal forces of two-storied framed building were calculated and compared in two different cases. in the first case the calculations are performed considering the settlements of the foundations. the settlements are calculated using 2 particular geological situations. in the second case all supports are assumed to be rigid. keywords: base ground, modulus subgrade reaction, settlements, redistribution of internal forces. the settlements of the foundations are a very significant factor, which affects the behaviour of structures of the designed building. if the settlements in the design process are not evaluated accurately, it may cause undesirable effects for the elements of the buildings: cracks and considerable deformations may occur in the constructions. the whole structure may even collapse. therefore, evaluation of those settlements is a substantial stage in the design process. different standards and recommendations, which limit the settlements of foundations exist. it is determined in appendix h of en-1997-1:2004: eurocode 7 (further – ec7) that for structures with individual foundations, the settlements up to 50 mm are acceptable. ec7 and other authors (eg. skempton and mcdonald (1956), polshin and tokar (1957), bjerrum (1963) and others) also limit the ratio of 61 journal of sustainable architecture and civil engineering 2016/1/14 settlements of adjacent foundations, because when the foundations settle irregularly, additional dangerous internal forces in the structures may be caused. on purpose to predict and avoid the negative effects of settlements of foundations, in the design process it is very important to describe and evaluate the interaction of soil particularly accurately. the mechanical behaviour of soil is very complex because of its nonlinear, heterogeneous and stress dependent nature. therefore, in the modelling of soil, frequently particular assumptions are admitted, simplifying the complex mechanical behaviour of soil. one of the most important assumptions is winkler’s (1867) suggested model. winkler’s (1867) local elastic deformations theory describes the soil as a spring, which has a particular stiffness. that stiffness is named the modulus of subgrade reaction ks and is one of the most significant magnitudes in the calculation of the settlements of foundations. it is a conceptual magnitude, which describes the ratio between applied load and the subsequent deformation of soil (bowles 1997). the main issue of winkler’s model is the calculation of the modulus of subgrade reaction ks. one of the first experiments which was made on purpose to obtain this magnitude was performed by terzaghi (1955), by loading the subgrade with a metal plate. however, these experimental results are not sufficiently accurate because of the fact that modulus of subgrade reaction depends not only on properties of soil, but also on the magnitude of load and geometrical parameters of the foundation, whereas these conditions are hardly achievable while performing the experiment with metal plates. as ziaie-moayed and janbaz (2009) observed, the method of terzaghi becomes inaccurate when dimensions of foundations are much greater than dimensions of the plate. the modulus of subgrade reaction depends on various factors: the width of foundation’s base (b), shape, the thickness of base, depth (d), the elastic modulus of material of foundation’s base (ef) and the moment of inertia (if), poisson’s ratio of soil (ν), the load which press the soil, the soil deformation modulus (e0) and etc. the shear deformation (poisson’s) coefficient of soil describes the ratio between shear and normal stresses. the tentative magnitudes of this coefficient may be chosen by rowe’s (2001) represented proposals: for clay in undrained conditions – 0,5; for clay in drained conditions – 0,2-0,3; for thick sand – 0,3-0,4; for powdery sand – 0,1-0,3. the modulus of subgrade reaction is a useful magnitude in modelling of foundations and subgrade interaction. as mentioned above, it does not depend on “internal” factors as the natural properties of soil, but also on “external” factors such as the geometrical characteristics of foundation or the magnitude of loading. for this reason, the modulus of subgrade reaction is not a fundamental property of soil. depending on the mentioned external factors, for the same soil, the coefficient ks may obtain different magnitudes. there does not exist a united calculation method of the modulus of subgrade reaction. therefore, the comparable analysis of different calculation methods was performed. further, ten different methods of calculation of coefficient ks are analysed and evaluated according to its accuracy. moreover, an influence of different settlements of foundations for structures is assessed. a comparable analysis of redistribution of the internal forces of the modelled constructional elements of the structure is performed by a computer-based program. the analysis consists of comparing the redistribution of internal forces when the settlements of all foundations are the same and the case where the settlements are different. calculation methods the first analysed method is the winkler´s model. this model describes the soil as an elastic system in which there is a linear dependence between the applied load and the subsequent settlements of the foundation. the mathematical value which describes this dependence, is the modulus subgrade reaction ks: where: f– applied load to the soil; s – foundation settlement. (1) s f k s = journal of sustainable architecture and civil engineering 2016/1/14 62 in order to determine the modulus subgrade reaction ks, the value of the settlement of the foundation (method no. 1) must be previously obtained. there are different ways to calculate these settlements. in this case, the method of addition was used, where the total settlement of the soil consists of the deformation of each small layer in which the soil is divided. using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. where: ef – elastic modulus of foundation; if – moment of inertia of the section of the foundation. (2) using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): (2) where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): (3) the value ks’ can be obtained using the next equation 2 0 12 4 0' 1 65,0      e ie be k ff s (4) where: – elastic modulus of foundation; – moment of inertia of the section of the foundation. for practical purpose vesic reduces the expression to (method no. 4): (5) according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): (6) where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) where: sf – safe factor; qa – allowable bear capacity. selvadurai (1984) proposed another method to obtain ks (method no. 7): (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1).  2 0 1-νbω e k s   b 'k k ss  fe fi 1...650 12 , ks  e0 b  1 v2    fss iimνb e δh δq k   2 0 1 as qsfk  40  2 0 1 650 νb e, k s    (3) the value ks’ can be obtained using the next equation using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): (2) where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): (3) the value ks’ can be obtained using the next equation 2 0 12 4 0' 1 65,0      e ie be k ff s (4) where: – elastic modulus of foundation; – moment of inertia of the section of the foundation. for practical purpose vesic reduces the expression to (method no. 4): (5) according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): (6) where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) where: sf – safe factor; qa – allowable bear capacity. selvadurai (1984) proposed another method to obtain ks (method no. 7): (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1).  2 0 1-νbω e k s   b 'k k ss  fe fi 1...650 12 , ks  e0 b  1 v2    fss iimνb e δh δq k   2 0 1 as qsfk  40  2 0 1 650 νb e, k s    for practical purpose vesic reduces the expression using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): (2) where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): (3) the value ks’ can be obtained using the next equation 2 0 12 4 0' 1 65,0      e ie be k ff s (4) where: – elastic modulus of foundation; – moment of inertia of the section of the foundation. for practical purpose vesic reduces the expression to (method no. 4): (5) according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): (6) where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) where: sf – safe factor; qa – allowable bear capacity. selvadurai (1984) proposed another method to obtain ks (method no. 7): (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1).  2 0 1-νbω e k s   b 'k k ss  fe fi 1...650 12 , ks  e0 b  1 v2    fss iimνb e δh δq k   2 0 1 as qsfk  40  2 0 1 650 νb e, k s    to (method no. 4): (4) using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): (2) where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): (3) the value ks’ can be obtained using the next equation 2 0 12 4 0' 1 65,0      e ie be k ff s (4) where: – elastic modulus of foundation; – moment of inertia of the section of the foundation. for practical purpose vesic reduces the expression to (method no. 4): (5) according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): (6) where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) where: sf – safe factor; qa – allowable bear capacity. selvadurai (1984) proposed another method to obtain ks (method no. 7): (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1).  2 0 1-νbω e k s   b 'k k ss  fe fi 1...650 12 , ks  e0 b  1 v2    fss iimνb e δh δq k   2 0 1 as qsfk  40  2 0 1 650 νb e, k s    (5) (6) using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): (2) where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): (3) the value ks’ can be obtained using the next equation 2 0 12 4 0' 1 65,0      e ie be k ff s (4) where: – elastic modulus of foundation; – moment of inertia of the section of the foundation. for practical purpose vesic reduces the expression to (method no. 4): (5) according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): (6) where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) where: sf – safe factor; qa – allowable bear capacity. selvadurai (1984) proposed another method to obtain ks (method no. 7): (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1).  2 0 1-νbω e k s   b 'k k ss  fe fi 1...650 12 , ks  e0 b  1 v2    fss iimνb e δh δq k   2 0 1 as qsfk  40  2 0 1 650 νb e, k s    according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): (2) where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): (3) the value ks’ can be obtained using the next equation 2 0 12 4 0' 1 65,0      e ie be k ff s (4) where: – elastic modulus of foundation; – moment of inertia of the section of the foundation. for practical purpose vesic reduces the expression to (method no. 4): (5) according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): (6) where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) where: sf – safe factor; qa – allowable bear capacity. selvadurai (1984) proposed another method to obtain ks (method no. 7): (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1).  2 0 1-νbω e k s   b 'k k ss  fe fi 1...650 12 , ks  e0 b  1 v2    fss iimνb e δh δq k   2 0 1 as qsfk  40  2 0 1 650 νb e, k s    where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). 63 journal of sustainable architecture and civil engineering 2016/1/14 where: sf – safe factor; qa – allowable bear capacity. in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) selvadurai (1984) proposed another method to obtain ks (method no. 7): using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): (2) where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): (3) the value ks’ can be obtained using the next equation 2 0 12 4 0' 1 65,0      e ie be k ff s (4) where: – elastic modulus of foundation; – moment of inertia of the section of the foundation. for practical purpose vesic reduces the expression to (method no. 4): (5) according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): (6) where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) where: sf – safe factor; qa – allowable bear capacity. selvadurai (1984) proposed another method to obtain ks (method no. 7): (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1).  2 0 1-νbω e k s   b 'k k ss  fe fi 1...650 12 , ks  e0 b  1 v2    fss iimνb e δh δq k   2 0 1 as qsfk  40  2 0 1 650 νb e, k s    (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1). another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: using the principles of the elastic theory f. schleicher (1926) presented a mathematical expression to calculate the modulus subgrade reaction (method no. 2): (2) where: ω – form coefficient of the foundation (for squared elastic foundation slabs – ω=0,95; for squared rigid foundation slabs – ω=0,88); e0 – deformation modulus of soil. vesic (1961) considered the influence of the materials and the section of the foundation and proposed an expression to obtain ks (method no. 3): (3) the value ks’ can be obtained using the next equation 2 0 12 4 0' 1 65,0      e ie be k ff s (4) where: – elastic modulus of foundation; – moment of inertia of the section of the foundation. for practical purpose vesic reduces the expression to (method no. 4): (5) according to timoshenko and goodyear (1951) method to calculate foundation settlements, j. bowles (1997) proposed another equation to obtain ks (method no. 5): (6) where: if – influence factor, which depends on the ratio d/l and l/b (l– foundation length; b– foundation width; d – foundation slab depth) and on poisson’s ratio ν; is – influence factor, which depends on l’/b’ ratio (l’ and b’ – effective foundation dimensions), width of the soil layer, poisson’s coefficient ν and depth of the foundation d. m – number of corners contributing to settlement (at a corner of the footing m=1; at the centre m=4). in all of the presented methods modulus subgrade reaction ks is obtained from soil deformation modulus e0. however, this property sometimes is not known. therefore, it can be useful to count on other kind of approximations not depending on e0. j. bowles (1997) proposed a method in which modulus subgrade reaction ks can be obtained from the allowable bear capacity of the soil qa (method no. 6): (7) where: sf – safe factor; qa – allowable bear capacity. selvadurai (1984) proposed another method to obtain ks (method no. 7): (8) modulus ks can be obtained using finite-element analysis software autodesk robot structural analysis professional (further – autodesk robot) (method no. 8). this program obtains ks by predicting the settlements of a footing by the method of addition (which is used in the method no. 1).  2 0 1-νbω e k s   b 'k k ss  fe fi 1...650 12 , ks  e0 b  1 v2    fss iimνb e δh δq k   2 0 1 as qsfk  40  2 0 1 650 νb e, k s    (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). calculation of modulus subgrade reaction for a multi-layer soil in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) where: l1 – half of the length of the foundation; b1 – half of the foundation width; zi – upper depth of the considered layer. (12) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation and from the relative depth of the analysed layer . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: (13) the final joint properties of the overall multi-layered soil are calculated by these equations: (14)   sls hν e k   2 0 1       sl s hνν eν k    211 1 0                   22 1 22 1 11 2 1 2 1 22 22 1 2 111 0 arcsin 2 iii ii i, i itr, zbzl bl blzdd zblzbl e h k 2 1 2 1 2 1 zbld  l/bη  z/bζ  2 ki  ktr,i ktr,i i1 n     n i ,ii eke 1 00 another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). calculation of modulus subgrade reaction for a multi-layer soil in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) where: l1 – half of the length of the foundation; b1 – half of the foundation width; zi – upper depth of the considered layer. (12) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation and from the relative depth of the analysed layer . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: (13) the final joint properties of the overall multi-layered soil are calculated by these equations: (14)   sls hν e k   2 0 1       sl s hνν eν k    211 1 0                   22 1 22 1 11 2 1 2 1 22 22 1 2 111 0 arcsin 2 iii ii i, i itr, zbzl bl blzdd zblzbl e h k 2 1 2 1 2 1 zbld  l/bη  z/bζ  2 ki  ktr,i ktr,i i1 n     n i ,ii eke 1 00 in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the calculation of modulus subgrade reaction for a multi-layer soil journal of sustainable architecture and civil engineering 2016/1/14 64 thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). calculation of modulus subgrade reaction for a multi-layer soil in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) where: l1 – half of the length of the foundation; b1 – half of the foundation width; zi – upper depth of the considered layer. (12) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation and from the relative depth of the analysed layer . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: (13) the final joint properties of the overall multi-layered soil are calculated by these equations: (14)   sls hν e k   2 0 1       sl s hνν eν k    211 1 0                   22 1 22 1 11 2 1 2 1 22 22 1 2 111 0 arcsin 2 iii ii i, i itr, zbzl bl blzdd zblzbl e h k 2 1 2 1 2 1 zbld  l/bη  z/bζ  2 ki  ktr,i ktr,i i1 n     n i ,ii eke 1 00 and from the relative depth of the analysed layer another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). calculation of modulus subgrade reaction for a multi-layer soil in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) where: l1 – half of the length of the foundation; b1 – half of the foundation width; zi – upper depth of the considered layer. (12) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation and from the relative depth of the analysed layer . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: (13) the final joint properties of the overall multi-layered soil are calculated by these equations: (14)   sls hν e k   2 0 1       sl s hνν eν k    211 1 0                   22 1 22 1 11 2 1 2 1 22 22 1 2 111 0 arcsin 2 iii ii i, i itr, zbzl bl blzdd zblzbl e h k 2 1 2 1 2 1 zbld  l/bη  z/bζ  2 ki  ktr,i ktr,i i1 n     n i ,ii eke 1 00 . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). calculation of modulus subgrade reaction for a multi-layer soil in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) where: l1 – half of the length of the foundation; b1 – half of the foundation width; zi – upper depth of the considered layer. (12) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation and from the relative depth of the analysed layer . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: (13) the final joint properties of the overall multi-layered soil are calculated by these equations: (14)   sls hν e k   2 0 1       sl s hνν eν k    211 1 0                   22 1 22 1 11 2 1 2 1 22 22 1 2 111 0 arcsin 2 iii ii i, i itr, zbzl bl blzdd zblzbl e h k 2 1 2 1 2 1 zbld  l/bη  z/bζ  2 ki  ktr,i ktr,i i1 n     n i ,ii eke 1 00 where: l1 – half of the length of the foundation; b 1 – half of the foundation width; zi – upper depth of the considered layer. (12) (14) (15) (16) another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). calculation of modulus subgrade reaction for a multi-layer soil in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) where: l1 – half of the length of the foundation; b1 – half of the foundation width; zi – upper depth of the considered layer. (12) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation and from the relative depth of the analysed layer . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: (13) the final joint properties of the overall multi-layered soil are calculated by these equations: (14)   sls hν e k   2 0 1       sl s hνν eν k    211 1 0                   22 1 22 1 11 2 1 2 1 22 22 1 2 111 0 arcsin 2 iii ii i, i itr, zbzl bl blzdd zblzbl e h k 2 1 2 1 2 1 zbld  l/bη  z/bζ  2 ki  ktr,i ktr,i i1 n     n i ,ii eke 1 00 (13) the final joint properties of the overall multi-layered soil are calculated by these equations: another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). calculation of modulus subgrade reaction for a multi-layer soil in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) where: l1 – half of the length of the foundation; b1 – half of the foundation width; zi – upper depth of the considered layer. (12) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation and from the relative depth of the analysed layer . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: (13) the final joint properties of the overall multi-layered soil are calculated by these equations: (14)   sls hν e k   2 0 1       sl s hνν eν k    211 1 0                   22 1 22 1 11 2 1 2 1 22 22 1 2 111 0 arcsin 2 iii ii i, i itr, zbzl bl blzdd zblzbl e h k 2 1 2 1 2 1 zbld  l/bη  z/bζ  2 ki  ktr,i ktr,i i1 n     n i ,ii eke 1 00 another way to determine modulus of subgrade reaction is to apply the finite layer method. it is assumed that, under a footing, there are vertical shear forces between the particles of the soil, so that the soil behaves plastically. however, going deeper in the ground, it occurs that these shear forces become weaker and, at some depth, disappear. then, the considered soil behaves elastically. this means that there is a layer under the footing of thickness hsl in which there are plastic deformations. it is recommended to take hsl=1/4 b. the results obtained by some authors (gorbunov-posadov et al. (1984), zhemochkin b. n. and sinitsyn a. p. (1947)) are provided in (8) and (9) equations: (9) (10) the first equation (eq. 9) considers that the plastic layer can slide on the ground, which is under it (method no. 9); the other equation assumes that slip does not occur (method no. 10). calculation of modulus subgrade reaction for a multi-layer soil in most of analysed methods, modulus ks depends on other ground properties like deformation modulus e0, poisson’s coefficient ν and bear capacity qa. when under the footing is a one-layered soil, these properties are assumed be uniform and the modulus ks can be obtained simply using the considered methods. nevertheless, frequently ground consists of several layers with different type of soil, mechanical properties, granulometric composition, thickness, water saturation degree and etc. therefore, in order to calculate modulus subgrade reaction using the analysed methods and considering these different properties between soil layers, authors propose to apply the influence factor ki to each soil layer. this coefficient depends on the thickness and the depth of the considered layer. the thinner and deeper layer is the less significant layer. the influence factor ki also depends on the deformation modulus e0 of the layer and on the form and dimensions of the foundation. first of all transitional coefficient ktr,i is obtained: (11) where: l1 – half of the length of the foundation; b1 – half of the foundation width; zi – upper depth of the considered layer. (12) the transitional coefficient may be obtained from the tables presented by some authors (e. g., šližytė et al. (2012)). in this case ktr,i can be selected from the ratio between foundation and from the relative depth of the analysed layer . transitional coefficients ktr,i are normalized and the influence factor of layer is obtained: (13) the final joint properties of the overall multi-layered soil are calculated by these equations: (14)   sls hν e k   2 0 1       sl s hνν eν k    211 1 0                   22 1 22 1 11 2 1 2 1 22 22 1 2 111 0 arcsin 2 iii ii i, i itr, zbzl bl blzdd zblzbl e h k 2 1 2 1 2 1 zbld  l/bη  z/bζ  2 ki  ktr,i ktr,i i1 n     n i ,ii eke 1 00 (15) (16) applying this method, the significant ground depth is . for weak soils it can be adopted . analysis of the different methods in order to check the accuracy of the presented methods, the modulus subgrade reaction was obtained from four different geologies boreholes. two of them (geologies a and b) are one – layered soils and the other two (geologies c and d) are multi-layered soils. for each one of them, the modulus of subgrade reaction ks is calculated, applying three different vertical loads to a square shallow footing. the loads are: 500 kn, 1000 kn and 2000 kn. the dimensions of the square shallow foundation are selected in each case according to soil parameters and the magnitude of load, in the way that bearing capacity would not be exceeded (dimensions of foundations vary from 1,3 m to 3,6 m). the properties of each geological layer are presented in table 1. table 1. properties of the layers of the soil layer no. soil hsl, m qc, mpa e0, mpa c', kpa φ, ̊ γ, kn/m3 ν soil a 1 sand 0,20 5,0 15,0 1 32,6 1,85 0,25 soil b 1 clay 0,20 2,0 18,0 35,7 19,2 2,16 0,35 soil c 1 silty clay 0,45 1,5 11 15 18 19,4 0,30 2 clay 0,70 2,0 13 15 18 19,4 0,30 3 sandy silt 3,40 4,9 27 9 21 19,9 0,30 4 silty sand 0,50 14,3 48 3 35 18,1 0,25 5 sandy silt 0,50 7,3 27 9 21 19,9 0,30 6 silty sand 1,30 12,5 48 3 35 18,1 0,25 soil d 1 sand 0,20 5,5 16 35 18,0 0,25 2 sand 0,60 4,0 12 33 17,0 0,25 3 sand with some gravel 2,10 6,5 19 38 20,0 0,25 4 gravel 1,30 26,0 78 1,0 44 20,9 0,25 5 sandy silty clay 1,10 8,0 80 35,0 26 22,8 0,35 6 sandy gravel 0,60 11,0 33 1,0 41 21,0 0,25 7 sandy silty clay 4,80 14,0 140 35,0 26 22,8 0,35 where: hsl – layer thickness; qc – cone tip resistance; e0 – deformation modulus; c’ – effective cohesion; φ – soil friction angle; γ – weight; ν – poisson’s coefficient. the calculation of modulus ks was carried out for all 4 geological situations. the results were obtained using the 10 different analysed methods, which are shown in figures 1 and 2. winkler’s method (method no. 1) is assumed to be the standard with which the other method can be compared. the results obtained by methods no. 9 and 10 differed considerably: ks values were about 4 times bigger than those obtained using the other methods. as a consequence, methods no. 9 and 10 were not analysed.   ki i i1 n  qa  ki  qa,i i1 n  b,h  51 bh  2 (15) (16) applying this method, the significant ground depth is . for weak soils it can be adopted . analysis of the different methods in order to check the accuracy of the presented methods, the modulus subgrade reaction was obtained from four different geologies boreholes. two of them (geologies a and b) are one – layered soils and the other two (geologies c and d) are multi-layered soils. for each one of them, the modulus of subgrade reaction ks is calculated, applying three different vertical loads to a square shallow footing. the loads are: 500 kn, 1000 kn and 2000 kn. the dimensions of the square shallow foundation are selected in each case according to soil parameters and the magnitude of load, in the way that bearing capacity would not be exceeded (dimensions of foundations vary from 1,3 m to 3,6 m). the properties of each geological layer are presented in table 1. table 1. properties of the layers of the soil layer no. soil hsl, m qc, mpa e0, mpa c', kpa φ, ̊ γ, kn/m3 ν soil a 1 sand 0,20 5,0 15,0 1 32,6 1,85 0,25 soil b 1 clay 0,20 2,0 18,0 35,7 19,2 2,16 0,35 soil c 1 silty clay 0,45 1,5 11 15 18 19,4 0,30 2 clay 0,70 2,0 13 15 18 19,4 0,30 3 sandy silt 3,40 4,9 27 9 21 19,9 0,30 4 silty sand 0,50 14,3 48 3 35 18,1 0,25 5 sandy silt 0,50 7,3 27 9 21 19,9 0,30 6 silty sand 1,30 12,5 48 3 35 18,1 0,25 soil d 1 sand 0,20 5,5 16 35 18,0 0,25 2 sand 0,60 4,0 12 33 17,0 0,25 3 sand with some gravel 2,10 6,5 19 38 20,0 0,25 4 gravel 1,30 26,0 78 1,0 44 20,9 0,25 5 sandy silty clay 1,10 8,0 80 35,0 26 22,8 0,35 6 sandy gravel 0,60 11,0 33 1,0 41 21,0 0,25 7 sandy silty clay 4,80 14,0 140 35,0 26 22,8 0,35 where: hsl – layer thickness; qc – cone tip resistance; e0 – deformation modulus; c’ – effective cohesion; φ – soil friction angle; γ – weight; ν – poisson’s coefficient. the calculation of modulus ks was carried out for all 4 geological situations. the results were obtained using the 10 different analysed methods, which are shown in figures 1 and 2. winkler’s method (method no. 1) is assumed to be the standard with which the other method can be compared. the results obtained by methods no. 9 and 10 differed considerably: ks values were about 4 times bigger than those obtained using the other methods. as a consequence, methods no. 9 and 10 were not analysed.   ki i i1 n  qa  ki  qa,i i1 n  b,h  51 bh  2applying this method, the significant ground depth is b,h ⋅= 51 . for weak soils it can be adopted bh ⋅= 2 . 65 journal of sustainable architecture and civil engineering 2016/1/14 in order to check the accuracy of the presented methods, the modulus subgrade reaction was obtained from four different geologies boreholes. two of them (geologies a and b) are one – layered soils and the other two (geologies c and d) are multi-layered soils. for each one of them, the modulus of subgrade reaction ks is calculated, applying three different vertical loads to a square shallow footing. the loads are: 500 kn, 1000 kn and 2000 kn. the dimensions of the square shallow foundation are selected in each case according to soil parameters and the magnitude of load, in the way that bearing capacity would not be exceeded (dimensions of foundations vary from 1,3 m to 3,6 m). the properties of each geological layer are presented in table 1. analysis of the different methods table 1 properties of the layers of the soil layer no. soil hsl, m qc, mpa e0, mpa c’, kpa φ, ° γ, kn/m 3 ν soil a 1 sand 0,20 5,0 15,0 1 32,6 1,85 0,25 soil b 1 clay 0,20 2,0 18,0 35,7 19,2 2,16 0,35 soil c 1 silty clay 0,45 1,5 11 15 18 19,4 0,30 2 clay 0,70 2,0 13 15 18 19,4 0,30 3 sandy silt 3,40 4,9 27 9 21 19,9 0,30 4 silty sand 0,50 14,3 48 3 35 18,1 0,25 5 sandy silt 0,50 7,3 27 9 21 19,9 0,30 6 silty sand 1,30 12,5 48 3 35 18,1 0,25 soil d 1 sand 0,20 5,5 16 35 18,0 0,25 2 sand 0,60 4,0 12 33 17,0 0,25 3 sand with some gravel 2,10 6,5 19 38 20,0 0,25 4 gravel 1,30 26,0 78 1,0 44 20,9 0,25 5 sandy silty clay 1,10 8,0 80 35,0 26 22,8 0,35 6 sandy gravel 0,60 11,0 33 1,0 41 21,0 0,25 7 sandy silty clay 4,80 14,0 140 35,0 26 22,8 0,35 the calculation of modulus ks was carried out for all 4 geological situations. the results were obtained using the 10 different analysed methods, which are shown in fig. 1 and 2. winkler’s method (method no. 1) is assumed to be the standard with which the other method can be compared. the results obtained by methods no. 9 and 10 differed considerably: ks values were about 4 times where: hsl – layer thickness; qc – cone tip resistance; e0 – deformation modulus; c’ – effective cohesion; φ – soil friction angle; γ – weight; ν – poisson’s coefficient. journal of sustainable architecture and civil engineering 2016/1/14 66 bigger than those obtained using the other methods. as a consequence, methods no. 9 and 10 were not analysed. fig. 1. values for soil a (left) and soil b (right) in figure 1 ks values of one-layered soils a (sandy soil) and b (clayey soil) are shown, calculated using all the discussed methods. in both cases the calculations show common accuracy trends. the obtained results are quite similar, however using the reduction of vesic’s equation (method no. 3) and salvadurai’s expression (method no. 7), ks values are the lowest. it means that by these methods, coefficient ks is calculated too carefully. in the case of the second method of bowles (method no. 6) the difference of the obtained ks values, applying different magnitude loads, is the highest. fig. 2. values for soil c (left) and soil d (right) in figure 2 it is presented the subgrade modulus values (using 8 different methods) for soils c and d. soil c and d are composed of several different layers. therefore, influence factor ki is included in the calculations of modulus ks. in one-layered soil diagram (figure 1) it can be seen the resembling trends: using methods no. 3 and 7, the results keep a reserve (are not considerable); the results of method no. 6 are strongly dependent of the magnitude of the applied load. using the method no. 1, footing settlements were predicted by the addition method, and then the modulus of subgrade reaction ks was calculated (eq. 1). modulus ks is obtained directly from the definition of winkler’s theory. on the other hand, the other methods are approximations from which 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 k s , 10 4 kn /m method no. 500 kn 1000 kn 2000 kn 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 k s , 1 04 kn /m method no. 500 kn 1000 kn 2000 kn 0 2 4 6 8 10 12 14 1 2 3 4 5 6 7 8 k s , 1 04 kn /m method no. 500 kn 1000 kn 2000 kn 0 2 4 6 8 10 12 14 1 2 3 4 5 6 7 8 k s , 1 04 kn /m method no. 500 kn 1000 kn 2000 kn in fig. 1 ks values of one-layered soils a (sandy soil) and b (clayey soil) are shown, calculated using all the discussed methods. in both cases the calculations show common accuracy trends. the obtained results are quite similar, however using the reduction of vesic’s equation (method no. 3) and salvadurai’s expression (method no. 7), ks values are the lowest. it means that by these methods, coefficient ks is calculated too carefully. in the case of the second method of bowles (method no. 6) the difference of the obtained ks values, applying different magnitude loads, is the highest. fig. 1 values for soil a (left) and soil b (right) fig. 2 values for soil c (left) and soil d (right) fig. 1. values for soil a (left) and soil b (right) in figure 1 ks values of one-layered soils a (sandy soil) and b (clayey soil) are shown, calculated using all the discussed methods. in both cases the calculations show common accuracy trends. the obtained results are quite similar, however using the reduction of vesic’s equation (method no. 3) and salvadurai’s expression (method no. 7), ks values are the lowest. it means that by these methods, coefficient ks is calculated too carefully. in the case of the second method of bowles (method no. 6) the difference of the obtained ks values, applying different magnitude loads, is the highest. fig. 2. values for soil c (left) and soil d (right) in figure 2 it is presented the subgrade modulus values (using 8 different methods) for soils c and d. soil c and d are composed of several different layers. therefore, influence factor ki is included in the calculations of modulus ks. in one-layered soil diagram (figure 1) it can be seen the resembling trends: using methods no. 3 and 7, the results keep a reserve (are not considerable); the results of method no. 6 are strongly dependent of the magnitude of the applied load. using the method no. 1, footing settlements were predicted by the addition method, and then the modulus of subgrade reaction ks was calculated (eq. 1). modulus ks is obtained directly from the definition of winkler’s theory. on the other hand, the other methods are approximations from which 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 k s , 10 4 kn /m method no. 500 kn 1000 kn 2000 kn 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 k s , 1 04 kn /m method no. 500 kn 1000 kn 2000 kn 0 2 4 6 8 10 12 14 1 2 3 4 5 6 7 8 k s , 1 04 kn /m method no. 500 kn 1000 kn 2000 kn 0 2 4 6 8 10 12 14 1 2 3 4 5 6 7 8 k s , 1 04 kn /m method no. 500 kn 1000 kn 2000 kn in fig. 2 it is presented the subgrade modulus values (using 8 different methods) for soils c and d. soil c and d are composed of several different layers. therefore, influence factor ki is included in the calculations of modulus ks. in one-layered soil diagram (fig. 1) it can be seen the resembling trends: using methods no. 3 and 7, the results keep a reserve (are not considerable); the results of method no. 6 are strongly dependent of the magnitude of the applied load. using the method no. 1, footing settlements were predicted by the addition method, and then the modulus of subgrade reaction ks was calculated (eq. 1). modulus ks is obtained directly from 67 journal of sustainable architecture and civil engineering 2016/1/14 the definition of winkler’s theory. on the other hand, the other methods are approximations from which the modulus ks is calculated using the other soil and footing properties. therefore, method no. 1 is assumed to be the standard with which the other methods can be compared in order to determine its accuracy. the difference between each method and winkler’s (method no. 1) is calculated from the next equation: (17) the modulus ks is calculated using the other soil and footing properties. therefore, method no. 1 is assumed to be the standard with which the other methods can be compared in order to determine its accuracy. the difference between each method and winkler’s (method no. 1) is calculated from the next equation: (17) difference δ was calculated for each one of the soils and for each one of loading cases (500 kn, 1000 kn and 2000 kn), applying the different ks calculation methods. the unified δ value for each soil is obtained calculating average of the obtained values in each loading case. finally average δ value for one-layered soils (a and b) and average δ value for multi-layered soils (c and d) were obtained. the comparison analysis of these final δ results is presented in figure 5. fig. 3. method comparison with no.1 (winkler’s) method for one-layered a and b geologies (left diagram) and for multi-layered c and d geologies (right diagram). in figure 3 it can be noticed that the closest results to method 1 are obtained with methods no. 8 (autodesk robot) and no. 5 (j. bowles). in the case of one-layered (a and b) soils these methods are very precise. difference δ reach 6 % and 8 %, respectively. in the case of multi-layered (c and d) soils, δ is more considerable: for both is about 12 %. as far as these two mentioned methods (no. 8 and no. 5) are the most exact paths to obtain ks, it is recommended to apply them in the design of building foundations. also in figure 3 it can be seen that when the layer influence factor ki in the calculations of multi-layered soils is introduced, ks accuracy (δ) values changes (in comparison with the case of onelayered soils). for some methods (no. 5 and 8) the difference δ grows about 5-8 %. in other cases (method no. 3, 4, 6 and 7), the difference δ decreases up to 10 % (in this case, the introduction of influence factor ki increases the accuracy of the results). in method no. 2, δ remains similar: it just increases for multi-layered soils up to 2 %. broadly speaking, using any calculation method, the values of δ between one-layered and multi-layered soil do not differ more than 10 %. therefore, the use of layer influence factor ki is justified. constructional analysis structural analysis was carried out, using program autodesk robot. the goal was to explore the changes of internal forces in the structures, using modulus of subgrade reaction obtained by different methods. there were three methods used in the analysis: bowles’s equation (using influence 12 45 19 8 25 48 6 0 5 10 15 20 25 30 35 40 45 50 2 3 4 5 6 7 8 δ , % method no. 14 35 14 12 20 43 12 0 5 10 15 20 25 30 35 40 45 50 2 3 4 5 6 7 8 δ , % method no.   ks,i  ks,1 ks,1 100% difference δ was calculated for each one of the soils and for each one of loading cases (500 kn, 1000 kn and 2000 kn), applying the different ks calculation methods. the unified δ value for each soil is obtained calculating average of the obtained values in each loading case. finally average δ value for one-layered soils (a and b) and average δ value for multi-layered soils (c and d) were obtained. the comparison analysis of these final δ results is presented in fig. 5. fig. 3 method comparison with no.1 (winkler’s) method for one-layered a and b geologies (left diagram) and for multi-layered c and d geologies (right diagram) the modulus ks is calculated using the other soil and footing properties. therefore, method no. 1 is assumed to be the standard with which the other methods can be compared in order to determine its accuracy. the difference between each method and winkler’s (method no. 1) is calculated from the next equation: (17) difference δ was calculated for each one of the soils and for each one of loading cases (500 kn, 1000 kn and 2000 kn), applying the different ks calculation methods. the unified δ value for each soil is obtained calculating average of the obtained values in each loading case. finally average δ value for one-layered soils (a and b) and average δ value for multi-layered soils (c and d) were obtained. the comparison analysis of these final δ results is presented in figure 5. fig. 3. method comparison with no.1 (winkler’s) method for one-layered a and b geologies (left diagram) and for multi-layered c and d geologies (right diagram). in figure 3 it can be noticed that the closest results to method 1 are obtained with methods no. 8 (autodesk robot) and no. 5 (j. bowles). in the case of one-layered (a and b) soils these methods are very precise. difference δ reach 6 % and 8 %, respectively. in the case of multi-layered (c and d) soils, δ is more considerable: for both is about 12 %. as far as these two mentioned methods (no. 8 and no. 5) are the most exact paths to obtain ks, it is recommended to apply them in the design of building foundations. also in figure 3 it can be seen that when the layer influence factor ki in the calculations of multi-layered soils is introduced, ks accuracy (δ) values changes (in comparison with the case of onelayered soils). for some methods (no. 5 and 8) the difference δ grows about 5-8 %. in other cases (method no. 3, 4, 6 and 7), the difference δ decreases up to 10 % (in this case, the introduction of influence factor ki increases the accuracy of the results). in method no. 2, δ remains similar: it just increases for multi-layered soils up to 2 %. broadly speaking, using any calculation method, the values of δ between one-layered and multi-layered soil do not differ more than 10 %. therefore, the use of layer influence factor ki is justified. constructional analysis structural analysis was carried out, using program autodesk robot. the goal was to explore the changes of internal forces in the structures, using modulus of subgrade reaction obtained by different methods. there were three methods used in the analysis: bowles’s equation (using influence 12 45 19 8 25 48 6 0 5 10 15 20 25 30 35 40 45 50 2 3 4 5 6 7 8 δ , % method no. 14 35 14 12 20 43 12 0 5 10 15 20 25 30 35 40 45 50 2 3 4 5 6 7 8 δ , % method no.   ks,i  ks,1 ks,1 100% in fig. 3 it can be noticed that the closest results to method 1 are obtained with methods no. 8 (autodesk robot) and no. 5 (j. bowles). in the case of one-layered (a and b) soils these methods are very precise. difference δ reach 6 % and 8 %, respectively. in the case of multi-layered (c and d) soils, δ is more considerable: for both is about 12 %. as far as these two mentioned methods (no. 8 and no. 5) are the most exact paths to obtain ks, it is recommended to apply them in the design of building foundations. also in fig. 3 it can be seen that when the layer influence factor ki in the calculations of multi-layered soils is introduced, ks accuracy (δ) values changes (in comparison with the case of one-layered soils). for some methods (no. 5 and 8) the difference δ grows about 5-8 %. in other cases (method no. 3, 4, 6 and 7), the difference δ decreases up to 10 % (in this case, the introduction of influence factor ki increases the accuracy of the results). in method no. 2, δ remains similar: it just increases for multi-layered soils up to 2 %. broadly speaking, using any calculation method, the values of δ between one-layered and multi-layered soil do not differ more than 10 %. therefore, the use of layer influence factor ki is justified. structural analysis was carried out, using program autodesk robot. the goal was to explore the changes of internal forces in the structures, using modulus of subgrade reaction obtained by different methods. there were three methods used in the analysis: bowles’s equation (using influence factor for multi-layered soil) (method no. 5), calculation with autodesk robot (method constructional analysis journal of sustainable architecture and civil engineering 2016/1/14 68 no. 8) and winkler’s method (method no. 1). after the analysis, it was noticed that the values of the internal forces obtained from the different three methods were very similar: the differences were up to 1%. as a result, further in this work, only the internal forces obtained using the modulus of subgrade reaction calculated by method no. 5 will be shown. calculation scheme is represented in fig. 4. the modelled structure is a two-storied building. the height of the first storey is 3 m. the distance between the floor of the first storey and the bottom chord of the truss is 3 m. the first floor has five 6 meters long spans. the span of the second floor is 30 m. in the calculations, the transverse frame is being analysed. its step in the longitudinal direction of the building is 6 meters. fig. 4 calculation scheme factor for multi-layered soil) (method no. 5), calculation with autodesk robot (method no. 8) and winkler’s method (method no. 1). after the analysis, it was noticed that the values of the internal forces obtained from the different three methods were very similar: the differences were up to 1%. as a result, further in this work, only the internal forces obtained using the modulus of subgrade reaction calculated by method no. 5 will be shown. calculation scheme is represented in fig. 4. the modelled structure is a two-storied building. the height of the first storey is 3 m. the distance between the floor of the first storey and the bottom chord of the truss is 3 m. the first floor has five 6 meters long spans. the span of the second floor is 30 m. in the calculations, the transverse frame is being analysed. its step in the longitudinal direction of the building is 6 meters. fig. 4. calculation scheme the redistribution of internal forces was explored in the transverse frame of the structure. three different geological situations were assumed in order to carry out the analysis: a) situation no. 1: absolutely rigid soil under all the supports of the building. b) situation no. 2: relatively weak soil (soil e) under all the supports of the building. c) situation no. 3: relatively strong soil (soil f) under supports s1 and s2; relatively weak soil (soil e) under supports s3, s4, s5 and s6. now the soil was chosen to be different from the soil used in the previous chapter. the soil in this chapter was chosen with the purpose to give potentially extreme differences of internal forces. the elastic behaviour of the soil is modelled introducing springs in the situations no. 2 and no. 3. the elastic modulus of those springs is the modulus of subgrade reaction of the considered soils e and f. the properties of soils e and f are shown in table 2. those characteristics have been obtained by evaluating geological boreholes from the same construction site. in spite of their proximity, their characteristics are considerably different. table 2. characteristics of layers of soils e and f layer no. soil hsl, m qc, mpa e0, mpa c', kpa φ, ̊ γ, kn/m3 ν soil e 1 sand 2,1 3,0 9 32 21,0 0,25 2 coarse sand 1,2 6,0 18 33 18,0 0,2 3 coarse sand 1,1 3,0 9 33 17,5 0,2 4 coarse sand 0,8 11,0 33 1,0 37 21,0 0,2 5 sandy silty clay 1,2 6,0 60 70,0 26 23,0 0,3 soil f 3 sand with some gravel 1,1 11 37 1 37 19,5 0,25 4 sand with some gravel 1,6 9 36 1 36 19,0 0,25 the redistribution of internal forces was explored in the transverse frame of the structure. three different geological situations were assumed in order to carry out the analysis: a) situation no. 1: absolutely rigid soil under all the supports of the building. b) situation no. 2: relatively weak soil (soil e) under all the supports of the building. c) situation no. 3: relatively strong soil (soil f) under supports s1 and s2; relatively weak soil (soil e) under supports s3, s4, s5 and s6. now the soil was chosen to be different from the soil used in the previous chapter. the soil in this chapter was chosen with the purpose to give potentially extreme differences of internal forces. the elastic behaviour of the soil is modelled introducing springs in the situations no. 2 and no. 3. the elastic modulus of those springs is the modulus of subgrade reaction of the considered soils e and f. the properties of soils e and f are shown in table 2. those characteristics have been obtained by evaluating geological boreholes from the same construction site. in spite of their proximity, their characteristics are considerably different. the bending moment diagrams under the three different described situations are shown in fig. 5. note: boxes of internal forces of columns have solid lines. boxes of internal forces of beams have dashed lines. values of bending moments in fig. 5 are divided by 527,67 in beams and by 161,7 in columns (maximum values). in fig. 5, it can be noticed that, when the springs are introduced (situation no. 2) instead of rigid supports (situation 1), bending moments in the beams increase up to 43 %. the maximum increase of bending moments can be noticed in beams b1 and b5, in the places, where those beams are connected to columns c1 and c6 respectively. however, the values of bending moments in several beams decrease. the biggest decline of bending moments is noticed in the places, where beams are connected to columns c2 and c5. in these places the values of bending moments de69 journal of sustainable architecture and civil engineering 2016/1/14 table 2 characteristics of layers of soils e and f layer no. soil hsl, m qc, mpa e0, mpa c’, kpa φ, ° γ, kn/m 3 ν soil e 1 sand 2,1 3,0 9 32 21,0 0,25 2 coarse sand 1,2 6,0 18 33 18,0 0,2 3 coarse sand 1,1 3,0 9 33 17,5 0,2 4 coarse sand 0,8 11,0 33 1,0 37 21,0 0,2 5 sandy silty clay 1,2 6,0 60 70,0 26 23,0 0,3 soil f 3 sand with some gravel 1,1 11 37 1 37 19,5 0,25 4 sand with some gravel 1,6 9 36 1 36 19,0 0,25 5 coarse sand 2,0 4 12 33 17,5 0,2 6 coarse sand 0,5 12 36 1 38 21,0 0,2 7 sandy silty clay 1,5 5 50 70 26 23,0 0,3 where: hsl – layer thickness; qc – cone tip resistance; e0 – deformation modulus; c’ – effective cohesion; φ – soil friction angle; γ – weight; ν – poisson’s coefficient. fig. 5 diagrams of bending moments table 3 legend of the diagrams 5 coarse sand 2,0 4 12 33 17,5 0,2 6 coarse sand 0,5 12 36 1 38 21,0 0,2 7 sandy silty clay 1,5 5 50 70 26 23,0 0,3 where: hsl – layer thickness; qc – cone tip resistance; e0 – deformation modulus; c’ – effective cohesion; φ – soil friction angle; γ – weight; ν – poisson’s coefficient. the bending moment diagrams under the three different described situations are shown in fig. 5. note: boxes of internal forces of columns have solid lines. boxes of internal forces of beams have dashed lines. values of bending moments in fig. 5 are divided by 527,67 in beams and by 161,7 in columns (maximum values). fig. 5. diagrams of bending moments table 3. legend of the diagrams case marking note 1. situation no. 1 2. situation no. 2 3. situation no. 3 in figure 5, it can be noticed that, when the springs are introduced (situation no. 2) instead of rigid supports (situation 1), bending moments in the beams increase up to 43 %. the maximum increase of bending moments can be noticed in beams b1 and b5, in the places, where those beams are connected to columns c1 and c6 respectively. however, the values of bending moments in several beams decrease. the biggest decline of bending moments is noticed in the places, where beams are connected to columns c2 and c5. in these places the values of bending moments decreased by up to 21 %. there are also significant differences of bending moments in the columns. bending moments increased by up to 41 % at the top of the columns c1 and c6. introducing different types of soil (situation no. 3) and comparing it to the results obtained from situation no. 2, where there is only one type of soil, changes are also noticeable. the maximum increase of bending moments, 72 %, can be noticed in beam b1, in the place where this beam is connected to column c2. comparing the latter situations, there is a considerable decrease of bending moments in some structures. for example, the bending moment in the midspan of beam b1 was up to 21 %. although the changes of bending moments in columns are not so significant, they should also be evaluated. the most noticeable decrease, 23 % occurred at the top of column c1. the increase of bending moments in columns is not considerable. diagrams of axial forces under three types of soil rigidity situations are represented in fig. 6 those situations are represented in table 3. note: values of axial forces in fig. 6 are divided by the value of maximum axial force 782,76. case marking note 1. situation no. 1 2. situation no. 2 3. situation no. 3 creased by up to 21 %. there are also significant differences of bending moments in the columns. bending moments increased by up to 41 % at the top of the columns c1 and c6. introducing different types of soil (situation no. 3) and comparing it to the results obtained from situation no. 2, where there is only one type of soil, changes are also noticeable. the maximum increase of bending moments, 72 %, can be noticed in beam b1, in the place where this beam is connected to column c2. comparing the latter situations, there is a considerable decrease of bending moments in some structures. for example, the bending moment in the midspan of beam b1 was up to 21 %. although the changes of bending moments in columns are not so significant, they should also be evaluated. the most noticeable decrease, 23 % occurred at the top of column c1. the increase of bending moments in columns is not considerable. journal of sustainable architecture and civil engineering 2016/1/14 70 diagrams of axial forces under three types of soil rigidity situations are represented in fig. 6 those situations are represented in table 3. note: values of axial forces in fig. 6 are divided by the value of maximum axial force 782,76. fig. 6 diagrams of axial forces fig. 6. diagrams of axial forces maximum and minimum axial forces in columns were obtained. however, under all of those situations tension did not occur and the differences of axial forces are very low. as a consequence, maximum axial forces are more relevant and only the changes of maximum axial forces will be discussed. in the column c1 there are no large differences of axial forces under the three situations of soil rigidity. in this column there is no difference between the results obtained from situations no. 2 and no. 1. there are significant changes under the situation no. 3, when axial force decreases by 5 %. in the column c2 the changes of axial forces under situation no. 2 decrease 6 % in comparison to situation no. 1. under the situation no. 3, axial force increases by up to 10 %. axial forces in column c3 under situations no. 1 and no. 2 are similar. however, in the situation no. 3 the axial forces of this column decrease by 15 %. there are no considerable changes of the axial forces in columns c4 and c6. axial forces in column c5 only diverge under the situation no. 1. under the elastic situations (no. 2 and 3) the values of axial forces decreased by 6 % in comparison to situation no. 1. diagrams of lateral forces under three types of soil rigidity cases are represented in fig. 7. those cases are represented in table 3. note: values of lateral forces in fig. 7 are divided by 382,63 in beams and by 73,5 in columns (maximum values). fig. 7. diagrams of shear forces when the springs are introduced (situation no. 2) instead of rigid supports (situation no. 1), the lateral forces in the beams increase by up to 7 %. this maximum increase is noticed in beams b1 maximum and minimum axial forces in columns were obtained. however, under all of those situations tension did not occur and the differences of axial forces are very low. as a consequence, maximum axial forces are more relevant and only the changes of maximum axial forces will be discussed. in the column c1 there are no large differences of axial forces under the three situations of soil rigidity. in this column there is no difference between the results obtained from situations no. 2 and no. 1. there are significant changes under the situation no. 3, when axial force decreases by 5 %. in the column c2 the changes of axial forces under situation no. 2 decrease 6 % in comparison to situation no. 1. under the situation no. 3, axial force increases by up to 10 %. axial forces in column c3 under situations no. 1 and no. 2 are similar. however, in the situation no. 3 the axial forces of this column decrease by 15 %. there are no considerable changes of the axial forces in columns c4 and c6. axial forces in column c5 only diverge under the situation no. 1. under the elastic situations (no. 2 and 3) the values of axial forces decreased by 6 % in comparison to situation no. 1. diagrams of lateral forces under three types of soil rigidity cases are represented in fig. 7. those cases are represented in table 3. note: values of lateral forces in fig. 7 are divided by 382,63 in beams and by 73,5 in columns (maximum values). fig. 7 diagrams of shear forces fig. 6. diagrams of axial forces maximum and minimum axial forces in columns were obtained. however, under all of those situations tension did not occur and the differences of axial forces are very low. as a consequence, maximum axial forces are more relevant and only the changes of maximum axial forces will be discussed. in the column c1 there are no large differences of axial forces under the three situations of soil rigidity. in this column there is no difference between the results obtained from situations no. 2 and no. 1. there are significant changes under the situation no. 3, when axial force decreases by 5 %. in the column c2 the changes of axial forces under situation no. 2 decrease 6 % in comparison to situation no. 1. under the situation no. 3, axial force increases by up to 10 %. axial forces in column c3 under situations no. 1 and no. 2 are similar. however, in the situation no. 3 the axial forces of this column decrease by 15 %. there are no considerable changes of the axial forces in columns c4 and c6. axial forces in column c5 only diverge under the situation no. 1. under the elastic situations (no. 2 and 3) the values of axial forces decreased by 6 % in comparison to situation no. 1. diagrams of lateral forces under three types of soil rigidity cases are represented in fig. 7. those cases are represented in table 3. note: values of lateral forces in fig. 7 are divided by 382,63 in beams and by 73,5 in columns (maximum values). fig. 7. diagrams of shear forces when the springs are introduced (situation no. 2) instead of rigid supports (situation no. 1), the lateral forces in the beams increase by up to 7 %. this maximum increase is noticed in beams b1 71 journal of sustainable architecture and civil engineering 2016/1/14 when the springs are introduced (situation no. 2) instead of rigid supports (situation no. 1), the lateral forces in the beams increase by up to 7 %. this maximum increase is noticed in beams b1 and b5, in the connections to columns c1 and c6. the decrease of lateral forces in some of the beams is also considerable. maximum decrease is noticed in beam b2, in the connection to column c2. this maximum decrease reaches 6 %. when comparing situation no. 2 to situation no. 1, it can be seen, that lateral forces increase in all of the columns of the first floor (columns c1 to c6). the maximum increase, up to 38 %, occurs in columns c1 and c6. comparing the values of the lateral forces obtained from situation no. 3 to the results obtained from situation no. 3, significant changes can be noticed. the maximum increase of lateral forces occurs in beam b2, in its connection to column c2. the values obtained in situation no. 3 are 21 % larger than in situation no. 2. the maximum decrease is also in beam b2. this decrease is noted at the place where the beam b2 is connected to the column c3. the values obtained in situation no. 3 decrease 18 % in comparison to situation no. 2. while comparing the changes of lateral forces in columns under situation no. 3 to situation no. 2, the maximum increase, up to 28 %, can be noticed in columns c4 and c5. the maximum decrease also occurs in the same columns. it is possible because there are many load combinations. this leads to the fact that there are diagrams on both sides of the columns. lateral forces increase on one side and decrease on the other side. 1 the comparable analysis of calculation methods of the modulus of subgrade reaction was performed. when analysing it was assumed that the most realistic results are obtained with the first method (winkler’s). the accuracy of other methods was determined by comparing those methods with the method no. 1 in calculating the difference δ. the closest results to first method were derived from calculation methods no. 5 (bowles) and no. 8 (autodesk robot) where the difference δ does not exceed 12 %. applying methods no. 2, 4 and 6 the value difference δ oscillate vary from 12 % to 25 %. the largest difference from the first method is obtained calculating by methods no. 3 (simplified vesic’s equation) and no. 7 (selvadurai) when the difference δ reaches 48 %. 2 most of the considered methods are dedicated to homogenous soils. however, in practise often occurs that the soil is consisted of many layers, which have different properties. in order to calculate the modulus of subgrade reaction of such soil, it is proposed to use the layer influence factor ki. by some methods (method no. 5 and 8) the difference of methods increased in one-layer case by 5 %. the difference δ of other methods remained similar or even less than δ of these methods in one-layer case. the differences δ, while calculating the coefficient ks by the same method for one-layered and multi-layered soil, never differed more than 10 %. therefore, the application of the coefficient ki is advisable and rational in the determination of the modulus of subgrade reaction of a multi-layered soil. 3 when the analysis of considered building was performed, it was determined that eval-uation of the modulus of subgrade reaction has considerable influence for the internal forces of the structures. redistribution of internal forces occurred with particular intensity when there were modelled different base ground stiffness (situation no. 3) under supports s1 and s2. redistribution of bending moments was the most relevant: under situation no. 3 it increased more than 70 %. moreover, there was a considerable variation of shear forces in the columns. evaluating the base ground stiffness (situation no. 2) and comparing it with the internal forces of the case where the supports are rigid (situation no. 1), the increase reached even 40 %. in beams considerable changes of shear forces were determined introducing the different types of soil (situation no. 3). it exceeded 20 %. the changes of axial forces were not such considerable (up to 10 %). however, the evaluation of those changes is essential. 4 the analysis of structures was performed evaluating the different modulus of subgrade reaction in several cases: bowles’s method (no. 5), winkler’s method (no. 1) and autodesk robot method (no. 8). obtained internal forces were compared in all cases. calculating the stiffconclusions journal of sustainable architecture and civil engineering 2016/1/14 72 ness with method no. 5 (using the influence factor for multi-layered soil ki) and comparing it with the other chosen methods, inconsiderable differences were obtained (up to 1 %). as a consequence, it is obvious that results obtained from method no. 5 are accurate, and that influence factor ki is reliable and appropriate to use in the analysis of multi-layered soils. en 1997-2 (2007) (english): eurocode 7: geotechnical design part 2: ground investigation and testing. bowles, j. e. foundation analysis and design. 5th ed. new york: mc graw-hill; 1997. bjerrum l. contribution to the discussion. sect. 6, 6th e.c.s.m.f.e., 1963; wiesbaden; vol. 2: 135-137. gorbunov-posadov m.i., malikova t. a., solomin v. i. calculation of structures of elastic bed. moscow: stroyizdat; 1984. polshin d. e., tokar r. a. maximum allowable non-uniform settlement of structures. 4th i.c.s.m.f.e., 1957; london; vol. 1: 402-405. rowe, r. k. geotechnical and geoenvironmental engineering handbook. 1st ed., new york, springer science + bussiness media, 2001. sadrekarimi, j. comparative study of methods of determination of coefficient of subgrade reaction. electronic journal of geotechnical engineering, 2009, vol. 14, bund. e. schleicher, f. zur theorie des baugrundes [the theory of soils]. bauingenieur, 1926; 7: 931–935, 949–952. selvadurai, a.p.s. the flexure of an infinite strip of finite width embedded in an isotropic elastic medium of finite extent. int. j. numer. anal. meth. geomech., 1984; 8: 157-166. skempton a. w., mcdonalds d. h. allowable settlements of buildings. proc. i.c.e, 1956; london; vol 5: 727-768. šližytė, d., medzvieckas, j., mackevičius, r. pamatai ir pagrindai [foundations and grounds]. vilnius: technika; 2012. vesic, a. b.beams on elastic subgrade and the winkler’s hypothesis. proceedings of 5th international conference of soil mechanics, 1961; paris: 845-850. terzaghi, k. v. evaluation of coefficient of subgrade reaction, geotechnique,1955; 5(4): 297-326. ziaie-moayed, r., janbaz, m. effective parameters on modulus of subgrade reaction in clayey soils”. journal of applied sciences, 2009; 9 (22): 40064012. zhemochkin b. n., sinitsyn a. p. practical methods of calculation for beams and slabs on elastic foundation without usig the winkler hypothesis. moscow: gosstroyizdat; 1947. ignacio villalon fornes master’s degree student kaunas university of technology, department of building structures. main research area calculation and analysis of building structures adress studentu st. 48, lt-51367, kaunas, lithuania tel.: +370 675 79085 e-mail: naxo. villalon@gmail.com references deividas martinavičius master’s degree student kaunas university of technology, department of building structures. main research area calculation and analysis of building structures adress studentu st. 48, lt-51367, kaunas, lithuania tel.: +370 616 87407 e-mail: deividas. martinavicius@ktu. edu mindaugas gricius master’s degree student kaunas university of technology, department of building structures. main research area calculation and analysis of building structures adress studentu st. 48, lt-51367, kaunas, lithuania tel.: +370 626 71664 e-mail: mindaugas. gricius@ktu.edu šarūnas kelpša lecturer kaunas university of technology, department of building structures main research area reinforced concrete. structural analysis. address studentu st. 48, lt-51367, kaunas, lithuania tel.: +370 37 30 04 73 e-mail: sarunas. kelpsa@ktu.lt mindaugas kasiulevičius director jsc “smailusis skliautas” main research area timber structures. structural analysis adress piliakalnio st. 3, lt-46224 kaunas, lithuania tel.: +370 37 33 04 40 e-mail: mindaugas kasiulevicius@ yachoo.com about the authors journal of sustainable architecture and civil engineering 2020/2/27 108 *corresponding author: nele.nutt@taltech.ee moisture buffer value of composite material made of claysand plaster and wastepaper received 2020/06/02 accepted after revision 2020/05/04 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 108-115 doi 10.5755/j01.sace.27.2.25391 moisture buffer value of composite material made of clay-sand plaster and wastepaper jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.25391 nele nutt* tallinn university of technology, department of civil engineering and architecture, school of engineering, academy of architecture and urban studies, ehitajate tee 5, 19086 tallinn, estonia tallinn university of technology, tartu college, school of engineering, puiestee 78, 51008 tartu, estonia the scope of the nordtest method is to evaluate the moisture buffer value (mbv) for materials exposed to indoor air. the test is intended to simulate daily variations with relative humidity (rh) of 75% during 8 hours and 33% during 16 hours. the specimen made according to a recipe contains the following: waste paper, glue, clay plaster mixture and water. eleven paper plaster mixtures with different percentages were used. test results showed that a large percentage of paper in the plaster increases the mbv. an impressive result, which needs to be studied further, was that the mbv was the highest in the mixture that consisted of 80% paper. keywords: composite material, clay-sand, moisture buffer value, nordtest, wastepaper. ardo kubjas tallinn university of technology, tartu college, school of engineering, puiestee 78, 51008 tartu, estonia due to the deepening problems of environmental pollution and global warming, the interest in environmentally friendly building materials and technology has increased in many fields of production, including in the building materials industry. this article introduces the properties of composite material made of two environmentally friendly materials: clay (clay plaster mixture) and paper. unburnt clay has the most extensive stocks and is one of the most widespread and readily accessible building materials in estonia. clay is a traditional building material that has been used for the construction of buildings and interiors. the on-site supply of material and energy-efficient technology are following the principle of sustainable development. in 2016 approximately 409 million tons of paper and cardboard products were manufactured in the world (forest products statistics), and this number increases every year. the demand for finding new ways to reuse waste, including wastepaper increases as circular economy and recycling becomes more and more popular. introduction 109 journal of sustainable architecture and civil engineering 2020/2/27 the mbv has been studied by several authors (vares et al. 2017, zhang et al. 2017, mazhoud et al. 2015, svennberg 2006, rode 2005). the results of previous laboratory studies of the mbv of interior finishing plaster made of wastepaper (teearu 2018) portray that the paper plaster mbv is excellent (mbv>2.0 = „excellent“) and the mbv of the composite material made of paper and clay (clay plaster mixture) is higher than the mbv of clay plaster (nutt et al. 2020). also, the effects of the technology used to make paper plaster (soolepp 2019) and the ingredients’ (glue mixture) effect on the mbv, and the environmental dangers of the wastewater which emerges when making paper plaster (allikvee 2019) have been studied. our hypothesis is based on our research (nutt et al. 2020) about the hygrothermal performance of clay-sand plaster and paper mixtures mbv. our experiment showed that adding paper to clay plaster mixtures changes the hydrothermal properties of the clay plaster mixture. the research determined that adding paper plaster to clay plaster increased the mbv of the plaster. our hypotheses: _ mbv increases when adding paper plaster mixture to clay plaster mixture. _ adding even a small amount of paper in the mixture has an impact on the mbv by increasing it. _ mbv depends on the amount of paper used. the more significant the proportion of paper in the mixture, the higher the moisture buffering value of plaster mixture. method and equipment in order to determine the moisture buffering characteristics of plaster, the nordtest methodology was used, which established the mbv of composite systems open to the indoor environment (rode 2005). at first, the specimen was kept at a temperature of 23±5⁰c with relative humidity (rh) of 50±5 % until a balance point was reached. balance point was considered to be reached when the change in the mass of two specimens was under 1% during two weigh-ins with 24 hours in-between. when the balanced moisture was established, the specimen was initially kept in an environment with rh of 75% for 8 hours and then in an environment with rh of 33% for 16 hours. throughout the whole experiment, the temperature was 23±5⁰c. the cycle was repeated until the average change in mass δm (g) of three continuous cycles was within 5% and the difference in each cycle of moisture absorption and drying out is smaller than 5% of the average change in mass, δm. nordtest protocol formula for mbvpractical [g/(m 2∙%rh)] calculations (equation 1): 2 the mbv has been studied by several authors (vares et al. 2017, zhang et al. 2017, mazhoud et al. 2015, svennberg 2006, rode 2005). the results of previous laboratory studies of the mbv of interior finishing plaster made of wastepaper (teearu 2018) portray that the paper plaster mbv is excellent (mbv>2.0 = „excellent“) and the mbv of the composite material made of paper and clay (clay plaster mixture) is higher than the mbv of clay plaster (nutt et al. 2020). also, the effects of the technology used to make paper plaster (soolepp 2019) and the ingredients’ (glue mixture) effect on the mbv, and the environmental dangers of the wastewater which emerges when making paper plaster (allikvee 2019) have been studied. our hypothesis is based on our research (nutt et al. 2020) about the hygrothermal performance of clay-sand plaster and paper mixtures mbv. our experiment showed that adding paper to clay plaster mixtures changes the hydrothermal properties of the clay plaster mixture. the research determined that adding paper plaster to clay plaster increased the mbv of the plaster. our hypotheses: 1. mbv increases when adding paper plaster mixture to clay plaster mixture. 2. adding even a small amount of paper in the mixture has an impact on the mbv by increasing it. 3. mbv depends on the amount of paper used. the more significant the proportion of paper in the mixture, the higher the moisture buffering value of plaster mixture. method and equipment in order to determine the moisture buffering characteristics of plaster, the nordtest methodology was used, which established the mbv of composite systems open to the indoor environment (rode 2005). at first, the specimen was kept at a temperature of 23±5⁰c with relative humidity (rh) of 50±5 % until a balance point was reached. balance point was considered to be reached when the change in the mass of two specimens was under 1% during two weigh-ins with 24 hours inbetween. when the balanced moisture was established, the specimen was initially kept in an environment with rh of 75% for 8 hours and then in an environment with rh of 33% for 16 hours. throughout the whole experiment, the temperature was 23±5⁰c. the cycle was repeated until the average change in mass δm (g) of three continuous cycles was within 5% and the difference in each cycle of moisture absorption and drying out is smaller than 5% of the average change in mass, δm. nordtest protocol formula for mbvpractical [g/(m2·%rh)] calculations (equation 1): 𝑀𝑀𝑀𝑀𝐵𝐵%& = )*+, )*./ 0∙( 34.543678) (1) where: mmin/max explain the moisture mass (min and max) in the final sample (g or kg); a – explain the exposed area m2; φ high/low – explain the high/low rh (75-33) levels applied in the measurement. nordtest method says that the specimen needs to be weighed five times in one cycle. we altered the testing method and weighed the specimen two times in one cycle as according to the methodology, only the data from two weigh-ins is necessary to calculate the mbv (equation 1). equipment included a climate chamber rumed 4101 affording rh 20...95% with accuracy ±23% and temperature from 0 to +60°c with accuracy ±0.5°c; memmert incubator oven inb200 (1) where: mmin/max explain the moisture mass (min and max) in the final sample (g or kg); a – explain the exposed area m2; φ high/low – explain the high/low rh (75-33) levels applied in the measurement. nordtest method says that the specimen needs to be weighed five times in one cycle. we altered the testing method and weighed the specimen two times in one cycle as according to the methodology, only the data from two weigh-ins is necessary to calculate the mbv (equation 1). equipment included a climate chamber rumed 4101 affording rh 20...95% with accuracy ±2-3% and temperature from 0 to +60°c with accuracy ±0.5°c; memmert incubator oven inb200 with a temperature range from +30 °c (however, at least 5 °c above ambient) up to +70 °c and digital balance kern plt 1200-3a with an accuracy of 0.001 g. the climate chamber method was used at environment temperature 23±0.5 °c with three specimens of each type. journal of sustainable architecture and civil engineering 2020/2/27 110 the specimen was made according to the recipe that contains: wastepaper (newspaper paper), glue (methylcellulose), clay plaster mixture and water. the total number of specimens was 33 (3 x 11). eleven different percentage plaster mixtures were used where paper plaster proportion were (g) 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%, in addition there were two control groups, paper plaster mixture and clay plaster mixture (fig. 1, table 1). a product by saviukumaja ltd fig. 1 examples of specimen groups, proportion of clay (%) p la st er g ro up p la st er co m po si tio n g ra in s iz e of cl ay p la st er (m m ) p ap er (g ) g lu e (g ) g lu e/ w at er c la y (g ) p ro po rt io n (c la y (% )) p ro po rt io n (p ap er (% )) n um be r of sa m pl es a ve ra ge ar ea (c m 2) a ve ra ge de ns ity (g /c m 3) 1 control paper 500 20/1000 0 0% 100% 3 75 0.3 2 control clay < 0.2 mm 100% 0% 3 83 2.0 3 clay + paper < 0.2 mm 0 20/1000 55 10% 90% 3 71 0.3 4 clay + paper < 0.2 mm 500 20/1000 125 20% 80% 3 70 0.4 5 clay + paper < 0.2 mm 500 20/1000 214 30% 70% 3 72 0.4 6 clay + paper < 0.2 mm 500 20/1000 333 40% 60% 3 70 0.5 7 clay + paper < 0.2 mm 500 20/1000 500 50% 50% 3 67 0.6 8 clay + aper < 0.2 mm 500 20/1000 750 60% 40% 3 69 0.7 9 clay + paper < 0.2 mm 500 20/1000 1166 70% 30% 3 70 0.9 10 clay + paper < 0.2 mm 500 20/1000 2000 80% 20% 3 72 1.1 11 clay + paper < 0.2 mm 500 20/1000 4 500 90% 10% 3 74 1.4 3 with a temperature range from +30 °c (however, at least 5 °c above ambient) up to +70 °c and digital balance kern plt 1200-3a with an accuracy of 0.001 g. the climate chamber method was used at environment temperature 23±0.5 °c with three specimens of each type. plaster mixtures and specimens the specimen was made according to the recipe that contains: wastepaper (newspaper paper), glue (methylcellulose), clay plaster mixture and water. the total number of specimens was 33 (3 x 11). eleven different percentage plaster mixtures were used where paper plaster proportion were (g) 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%, in addition there were two control groups, paper plaster mixture and clay plaster mixture (fig. 1, table 1). a product by saviukumaja ltd was used for clay plaster mixture, and it was a clay finishing plaster consisting of clay and sand with grain size 0-2 mm and had added fibre of the typha spadix. x-ray diffraction analysis helped to determine the mineralogical composition (% of mass) of clay plaster mixture (< 0.2 mm) : quartz 45.6, k-feldspar 6.6, plagioclase 7.9, chlorite 1.5, illite/illitesmectite 20.9, kaolinite 4.1, calcite 8.5, dolomite 4.0, hematite 0.5 and amphibole 0.5 wt% (altmäe et al. 2019). fig. 1. examples of specimen groups, proportion of clay (%) table 1. composition of mixtures plast er grou p plaster composit ion grai n size of clay plast er (mm ) pap er (g) glue (g) glue/wa ter cla y (g) proporti on (clay (%)) proporti on (paper (%)) numb er of sampl es avera ge area (cm2) avera ge densit y (g/cm 3) test report plaster mixtures and specimens was used for clay plaster mixture, and it was a clay finishing plaster consisting of clay and sand with grain size 0-2 mm and had added fibre of the typha spadix. x-ray diffraction analysis helped to determine the mineralogical composition (% of mass) of clay plaster mixture (< 0.2 mm) : quartz 45.6, k-feldspar 6.6, plagioclase 7.9, chlorite 1.5, illite/illite-smectite 20.9, kaolinite 4.1, calcite 8.5, dolomite 4.0, hematite 0.5 and amphibole 0.5 wt% (altmäe et al. 2019). table 1 composition of mixtures the method: nordtest type of product: composite plaster produce name: clay + paper plaster, homemade production: made in a laboratory 111 journal of sustainable architecture and civil engineering 2020/2/27 composition: paper + clay plaster + glue + water, material with homogenous structure description: specimen thickness 2.5 cm, the exposed surface area of a circle with a 9 cm diameter sealing: waterproof nitrile pouch with a thickness of 1.25 mm number of test specimens: 3 test configuration: temperature 23°c, low rh 33% for 16 hours (±10 min), high rh 75% for 8 hours (±10 min) test 1. dates of test 1: 23.06.2019 29.06.2019 test 2. dates of test 2: 02.08.2019 07.08.2019 test 3. dates of test 3: 17.08.2019 25.08.2019 the results nordtest results describe the moisture absorption and separation of plaster mixtures, which is expressed by an index mbv. in actual living spaces, the change in relative humidity is described by mbvpractical (janssen and roels 2009). as a result of the cyclic change of relative humidity, the weight of the specimens also changed in cycles (fig. 2). using the mbv [g/(m2∙%rh)@8/16h] materials can be classified as follows: negligible (0-0.2), limited (0.2-0.5), moderate (0.5-1.0), good (1.0-2.0), and excellent (2.0-) (rode 2005). fig. 2 nordtest test no 1: change in specimens’ mass 5 test 1. dates of test 1: 23.06.2019 29.06.2019 test 2. dates of test 2: 02.08.2019 07.08.2019 test 3. dates of test 3: 17.08.2019 25.08.2019 the results nordtest results describe the moisture absorption and separation of plaster mixtures, which is expressed by an index mbv. in actual living spaces, the change in relative humidity is described by mbvpractical (janssen and roels 2009). as a result of the cyclic change of relative humidity, the weight of the specimens also changed in cycles (fig. 2). using the mbv [g/(m2·%rh)@8/16h] materials can be classified as follows: negligible (0-0.2), limited (0.2-0.5), moderate (0.5-1.0), good (1.0-2.0), and excellent (2.0-) (rode 2005). fig. 2. nordtest test no 1: change in specimens’ mass. plaster group 4 (clay 20% and paper 80%). the continuous line portrays the change in moisture cycles (rh 33% ja rh 75%) in the climate chamber. hypothesis (2): adding even a small amount of paper in the mixture has an impact on the increase of the mbv is correct. all specimens that had paper added to (10-90%) increased the value of their mbv. clay plaster mixture (plaster group 2) has an mbv<2.0 g/(m2·%rh)@8/16h (“good”) which stays in the range of 1.91-1.98 g/(m2·%rh)@8/16h. all the mixtures that had paper added to it (plaster groups 3-11) had an mbv>2.0 g/(m2·%rh)@8/16h which stayed in the range of 2.123.17 g/(m2·%rh)@8/16h (“excellent”) (table 2). hypothesis (1): the mbv increases when adding paper plaster mixture to clay plaster mixture, and hypothesis (3): mbv depends on the amount of paper used. the more significant the proportion of paper in the mixture, the higher the mbv of plaster mixture was partially confirmed. when generally test results show that increasing the proportion of paper in the mixture increases the plaster mixture’s mbv, then in specific ratios, this trend was not noted. all three test results portrayed that the mbv was the highest (accordingly 3.10, 3.17, 3.14 g/(m2·%rh)@8/16h)) when the specimens consisted of 80% paper (plaster group 4). the mbv was even higher than the mbv of specimens that were made only from paper (plaster group 1) (table 2, fig. 3 (a)). hypothesis (2): adding even a small amount of paper in the mixture has an impact on the increase of the mbv is correct. all specimens that had paper added to (10-90%) increased the value of their mbv. clay plaster mixture (plaster group 2) has an mbv<2.0 g/(m2∙%rh)@8/16h (“good”) which stays in the range of 1.91-1.98 g/(m2∙%rh)@8/16h. all the mixtures that had paper added to it (plaster groups 3-11) had an mbv>2.0 g/(m2∙%rh)@8/16h which stayed in the range of 2.123.17 g/(m2∙%rh)@8/16h (“excellent”) (table 2). hypothesis (1): the mbv increases when adding paper plaster mixture to clay plaster mixture, and hypothesis (3): mbv depends on the amount of paper used. the more significant the proportion of paper in the mixture, the higher the mbv of plaster mixture was partially confirmed. when generally test results show that increasing the proportion of paper in the mixture increases the plaster mixture’s mbv, then in specific ratios, this trend was not noted. all three test results portrayed that the mbv was the highest (accordingly 3.10, 3.17, 3.14 g/(m2∙%rh)@8/16h)) when the specimens consisted of 80% paper (plaster group 4). the mbv was even higher than the mbv of specimens that were made only from paper (plaster group 1) (table 2, fig. 3 (a)). plaster group 4 (clay 20% and paper 80%). the continuous line portrays the change in moisture cycles (rh 33% ja rh 75%) in the climate chamber. journal of sustainable architecture and civil engineering 2020/2/27 112 p la st er g ro u p nu m be r p ap er % te st 1 m b v [g /( m 2· % r h )@ 8/ 16 h] m b v cl as si fi ca ti o n te st 2 m b v [g /( m 2· % r h )@ 8/ 16 h] m b v cl as si fi ca ti o n te st 3 m b v [g /( m 2· % r h )@ 8/ 16 h m b v cl as si fi ca ti o n 1 100 2.94 excellent* 3.05 excellent* 2.97 excellent* 3 90 2.99 excellent* 3.01 excellent* 3.10 excellent* 4 80 3.10 excellent* 3.17 excellent* 3.14 excellent* 5 70 2.91 excellent* 3.00 excellent* 3.01 excellent* 6 60 2.99 excellent* 3.04 excellent* 2.94 excellent* 7 50 2.78 excellent* 2.89 excellent* 3.01 excellent* 8 40 2.80 excellent* 2.88 excellent* 2.76 excellent* 9 30 2.65 excellent* 2.78 excellent* 2.68 excellent* 10 20 2.49 excellent* 2.49 excellent* 2.61 excellent* 11 10 2.18 excellent* 2.12 excellent* 2.31 excellent* 2 0 1.91 good* 1.91 good* 1.98 good* table 2 mbv of mixtures fig. 3 (a) mbv, (b) density and clay proportion, (c) mbv and density, (d) mbv and clay proportion *negligible (0-0.2), limited (0.2-0.5), moderate (0.5-1.0) good (1.0-2.0), excellent (2.0-). a c d b 113 journal of sustainable architecture and civil engineering 2020/2/27 the ratio of clay and paper has a strong impact (r2=0,976) on the density of the mixture (fig. 3 (b)). the densities of mixtures (plaster groups 3 – 11) are in the range of ρ=0.3 1.4 (g/cm3) (table 2). the larger the proportion of paper in the mixture, the smaller the density of the mixture. clay plaster mixture (plaster group 2) density is ρ=2.0 g/cm3 and paper plaster (plaster group 1) mixture density is ρ=0.3 g/cm3 (table 2). the density, in turn, had a strong effect on (r2=0,9554) the mbv of composite mixtures. the mbv increased as the density decreased (fig. 3 (c)). the ratio of clay and paper (r2=0,7749) also influenced the mbv. the higher the amount of paper was, the higher was the mbv (fig. 3 (d)). our experiment portrayed that the hydrothermal properties of clay plaster mixture change when the paper is added to the mixture. 1 adding paper to clay plaster mixtures enables the mbv’s classification to change from “good” (1.0-2.0) to “excellent” (>2.0). 2 all the specimen tested in the experiment that had paper added to (10-90%) had a higher mbv (mbv= 2.123.17 g/(m2∙%rh)@8/16h)) then the specimen that was made of clay plaster only. clay plasters mbv=1.91-1.98 g/(m2∙%rh)@8/16h. 3 mbv is dependant on the amount of paper added to the plaster mixture. mbvs of plaster mixtures with different paper ratios differ from each other. paper mixtures mbv=2.12 3.17g/ (m2∙%rh)@8/16h. 4 the ratio of clay and paper and mbv were strongly connected (r2=0,7749). 5 the proportion of paper in the mixture influenced the density of the mixture. the more significant the amount of paper in the mixture, the smaller the density of the mixture was. the density of paper mixtures ρ=0.3– 1.4 g/cm3 and clay plaster ρ=2.0 g/cm3. 6 there was a strong connection (r2=0,976) between the components (clay and paper ratio) of the mixture and density. 7 the higher the density of the mixture, the lower the mbv. 8 there was a secure connection between density and mbv(r2=0,9554). 9 plaster mixture made of 80% paper had the highest mbv (accordingly 3.10, 3.17, 3.14 g/ (m2∙%rh)@8/16h)). conclusions discussion the results of the study introduced in this article confirmed that by adding paper to clay plaster mixtures, the mbv of clay plaster is increased, which creates an opportunity to improve the properties of natural clay plaster and to improve the indoor climate of living spaces when using the created composite material. interior finishing materials have a significant effect on the indoor climate. the moisture buffering ability of materials is connected to the sorption and diffusion abilities. the materials used for interior finishing have an important role in the moisture stabilisation of indoor spaces. household activities affect the humidity in living spaces and as a result relative humidity can become too high or too low. the experiment showed that using wastepaper as a plaster component affects the moisture buffering ability, thus, the plaster mixture passively regulates indoor climate, which in particular is important in the nordic countries where people spend 70% of their time indoors. our hypothesis that adding paper to clay plaster increases the mbv was confirmed. the increase is caused by the difference in the technical properties of paper plaster and clay plaster moisture. previous studies have shown that the technical properties of clay plaster moisture are not as good as the technical properties of paper plaster moisture (altmäe et al. 2019) and the latter can be classified as a material with excellent moisture buffering abilities (teearu 2018). therefore, addjournal of sustainable architecture and civil engineering 2020/2/27 114 ing paper to the plaster mixture increases its mbv. to assess the effect of paper on the plaster’s porosity more precisely it is necessary to study the sorption ability (absorption, desorption) of the plaster mixture. before the results are put into practice in the construction industry it is necessary to study if the natural plasters intended to be used indoors can become suitable environments for microbes and mould to grow in due to their excellent moisture buffering ability. it is also necessary to study the long term effects on the indoor air quality to see if organic compounds are being separated into the air. the issues related to the fire resistance of plasters made of paper need to be studied as well. further research also starts to observe other moisture properties. the method described in the standard ”evs-en iso 12571:2013 hygrothermal performance of building materials and products – determination of hygroscopic sorption properties“ is used to study the sorption of water vapour when determining the hygroscopicity of porous materials. in order to study the conductivity of water vapour, the method from ”evs-en iso 12572:2016 hygrothermal performance of building materials and products determination of water vapour transmission properties cup method“ was used. also, it is energy efficient to use local building material clay, and the use of wastepaper also supports the circular economy and environment-friendly principles. before the results are put into practice in the construction industry it is necessary to study if the natural plasters intended to be used indoors can become suitable environments for microbes and mould to grow in due to their excellent moisture buffering ability. it is also necessary to study the long term effects on the indoor air quality to see if organic compounds are being separated into the air. the issues related to the fire resistance of plasters made of paper need to be studied as well. acknowledgement this study was supported by tartu college of tallinn university of technology. special thanks to aime ruus from tartu college of tallinn university of technology. the authors would like to thank kadri mets for improving the english of the manuscript. altmäe, e., ruus, a., raamets, j., and tungel, e. determination of clay-sand plaster hygrothermal performance: influence of different types of clays on sorption and water vapour permeability. in proceedings of the 9th international cold climate conference: sustainable new and renovated buildings in cold climates, kiruna, sweden, march 12-15, 2018 (johansson, d., bagge, h., and wahlström, å. eds). springer proceedings in energy, springer, cham, 2018, 945−955.https:// doi.org/10.1007/978-3-030-00662-4_80 allikvee, k. paberkrohvi reovee analüüsimine [analysis of paper plaster wastewater]. bachelor thesis. tallinn university of technology, tallinn, 2019. (in estonian). forest products statistics 2018. [www document]. url https://www.fao.org/forestry/statistics/80938/en/ [accessed 6 january 2020]. janssen, h., roels, s. qualitative and quantitative assessment of interior moisture buffering by enclosures. energy build., 2009, 41(4), 382-394.https:// doi.org/10.1016/j.enbuild.2008.11.007 mazhoud, b., collet, f., pretot, s., chamoin, j. hygric and thermal properties of hemp-lime plasreferences ters, buildenviron, 2016; 96: 206-216. https://doi. org/10.1016/j.buildenv.2015.11.013 nutt, n., kubjas, a., nei, l. hygrothermal performance: moisture buffer value of composite material clay-sand plaster made with wastepaper.proceedings of the estonian academy of sciences, 2020; 69(2): 162-177.https://doi.org/10.3176/proc.2020.3.01 rode, c. moisture buffering of building materials. byg dtu-126 report. department of civil engineering, technical university of denmark, kongens lyngby 2005. http://orbit.dtu.dk/fedora/objects/ orbit:75984/datastreams/file_2415500/content [accessed 6 january 2020]. soolepp, m. paberkrohvi tootmisviiside mõju paberkrohvi niiskustehnilistele omadustele [the effects of different production methods to hygrothermal properties of paper plaster], master’s thesis. building tallinn university of technology, tartu, 2019. (in estonian). svennberg, k. moisture buffering in the indoor environment. thesis building physics lth lund university, lund, 2006. http://www.byfy.lth.se/fileadmin/ 115 journal of sustainable architecture and civil engineering 2020/2/27 byfy/files/tvbh-1000pdf/tvbh-1016ksvweb.pdf [accessed 6 january 2020]. teearu, m.-l. paberkrohvi niiskustehniliste omaduste määramine: sorptsioon, veeauru läbilaskvus ning niiskuspuhverdusvõime (determinantion of hygrothermal performance of paper clay: sorption, water vapour permeability and moisture buffering) master’s thesis. tallinn university of technology, tartu, 2018. (in estonian). vares, o., ruus, a., raamets, j., tungel, e. determination of hygrothermal performance of clay-sand plaster: influence of covering on sorption and water vapour permeability. energy procedia, 2017, 132, 267272.https://doi.org/10.1016/j.egypro.2017.09.719 zhang, m., qin, m., chen, z. moisture buffer effect and its impact on indoor environment. procedia eng., 2017, 205, 1123-1129.https://doi.org/10.1016/j.proeng.2017.10.417 about the authors nele nutt a researcher architecture at academy of architecture and urban studies, department of civil engineering and architecture, school of engineering, tallinn university of technology and a senior lecturer at tartu college, school of engineering, tallinn university of technology main research area materials science, architecture and civil engineering. address puiestee 78, 51008 tartu, estonia tel. +372 6204 800 e-mail: nele.nutt@taltech.ee ardo kubjas doctoral student tartu college, school of engineering, tallinn university of technology main research area materials science, transportation and civil engineering. address puiestee 78, 51008 tartu, estonia tel. +372 6204 800 e-mail: ardo.kubjas@taltech.ee this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 20 aesthetics and safety of road landscape: are they related? irina matijošaitienė1*, kristina navickaitė2 1 kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania 2 kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania * corresponding author: irina.matijosaitiene@ktu.lt the problem of unsafe roads is very actual in lithuania. the solution of the problem is usually found in construction of road equipment. the paper covers another solution: the authors analyze road safety through aesthetic features of landscape. the identification of relations between safety and landscape aesthetic features will enable us to enhance safety by modeling road landscape. this untypical approach would lead to both achievements: decrease of road traffic accidents and increase of visual quality of road landscape. the correlation analysis enabled us to identify weak relations between the quantity of car accidents and some aesthetic properties of road landscape. regression analysis revealed the factors described by aesthetic properties which influence the quantity of car accidents on lithuanian roads. keywords: road landscape, aesthetics, safety, correlation analysis, linear regression analysis. darnioji architektūra ir statyba 2012. no. 1(1) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction according to eurostat statistical findings (transport … 2012) about road accidents in eu member countries during 2008, the highest road fatality rates were recorded in lithuania (148), poland (143), romania (142), bulgaria, greece and latvia (all 139) (here the values of road fatality rates are expressed as the number of deaths per million inhabitants). though during the last decade the number of car accidents on lithuanian roads decreased from 5972 in 2001 (1715 accidents per million inhabitants) to 3312 in 2011 (1035 accidents per million inhabitants) (eismo … 2012) and the fatality rates also decreased from 706 in 2001 (202 accidents per million inhabitants) to 297 in 2011 (93 accidents per million inhabitants) the overall road safety in lithuania is not high, having in mind lithuania’s position in the context of other eu member countries. for instance, road fatality rates in sweden and the united kingdom are both 43, in the netherlands 41 and in malta 37 per million inhabitants. lithuania try to solve the problem of unsafe roads through speed restriction on dangerous segments of roads, installation of safety islands, roundabouts etc. though many countries (usa, germany, great britain, australia etc.) involve road landscape aesthetics and design into enhancing of road safety. in these countries creation of an aesthetic road landscape is an essential part of creation a safe driving on the road. literature review revealed some analysis of road safety through the prism of landscape aesthetics. according to the national association of australian state road authorities (naasra) the main goal of road landscaping is „to produce roadways to high safety standards which will also aesthetically integrate with the environment“ (road … 1997). though the road landscape manual (1997) presents the assessment of the road landscape at visual-aesthetic, ecological (environmental) and cultural heritage consideration stages, road safety aspect has to be considered at all stages, including construction, operation and maintenance of roads (road … 1997). according to american experience billboards impact the visual quality of the highway because they obstruct the views of scenic features and the natural landscape (i-15 … 2005). advertising can also distract drivers through messages and products which are not relevant to travelling (road … 1997). j. edquist (2008) analyzed the effect of visual disorder on road safety. chaotically located road signs, advertising, buildings, electrical transmission lines etc. are called here as visual disorder. the scholar carried out the research of simulation of drivers’ behavior at day time. the result of her research revealed that visual disorder in road landscape decrease drivers’ attention while driving and negatively affect safety on the roads. h. antonson with a group of researchers (2009) analyzed the reliance of drivers’ behavior and safety on the road landscape type – open, woodlands or mixed. for the research they used the simulator of driving in these types of landscape. then eighteen research participants were asked to answer the questions about their feelings while driving. the research results indicated that in the open landscape the speed of driving is faster, and that road safety depends on the landscape through which http://dx.doi.org/10.5755/j01.sace.1.1.2613 21 road passes. h. drottenborg (2002) analyzed traffic safety and driving behavior in 10 beautiful and 10 ugly traffic environments. the results confirmed that “aesthetically rewarding traffic environments seem to be beneficial for traffic safety”, and that driving speed is lower in beautiful rather than ugly traffic environments due to more stops in beautiful landscape. research in germany demonstrated that the most part (68%) of all the car accidents happen due to the wrong design of road and its landscape, and because of insufficient informativity of road and its landscape. according to küllers’ model of the basic emotional process, “driving behavior is related to the physical environment, other road users, the driving task, the individual factors and own abilities, and to the interaction among them” (drottenborg, 2002). therefore, this research is concentrated on the physical environment, id est the landscape through which the road passes. accordingly, the aim of the research is to identify if there is a relation between landscape aesthetics and safety on lithuanian roads. 2. methods the research objects are the main lithuanian highways which are marked as the european motorway network corridors or the european highways: a1 road vilnius-kaunas-klaipėda (311.40 km), a2 road vilniuspanevėžys (135.92 km), a3 road vilnius-minsk (belarus) (33.99 km), a5 road kaunas-marijampolė-suwalki (poland) (97.06 km), a6 road kaunas-zarasai-daugavpils (latvia) (185.40 km), a8 road panevėžys-aristava-sitkūnai (87.86 km), a9 road panevėžys-šiauliai (78.94 km), a10 road panevėžys-pasvalys-bauska (latvia) (66.10 km), a11 road šiauliai-palanga (146.85 km), a12 road riga (latvia)šiauliai-tauragė-kaliningrad (russia) (186.09 km), a13 road klaipėda-liepaja (latvia) (45.15 km) and a16 road vilnius-prienai-marijampolė (137.51 km) (fig. 1). the total length of the researched roads is 1512.27 km. only the road segments within the lithuanian borders were considered. the research of aesthetic properties of road landscape was conducted in spring 2010 by employing the photofixation of road landscape and the qualitative survey (matijošaitienė 2011). selected photos of road landscape were used for the qualitative survey. also aesthetic properties of road landscape were used for the survey and for the analysis of aesthetics and road safety: interesting, natural, visually safe, skittish, beautiful, outstanding, harmonious, sophisticated, relaxing, majestic, pleasant, elements match for surrounding environment, left an intense positive impression, willing to drive on this road. these properties were measured by the 5-point semantic differential scale, where 1 meant the least acceptance and 5 meant the most acceptance (matijošaitienė and stankevičė 2011). thus, the aesthetic properties of road landscape are based on respondents’ emotions and their opinion about a certain road landscape. the number of respondents was n=486. pasw statistics 17.0 software was applied for the correlation and regression analysis of the data. correlation analysis was applied for the identification of relations between all or separate variables, and if there was a relation this analysis will enable us to identify the strength of the relation. the variables describing demographic, financial and marital status of respondents are nominal and interval (for the measurement of respondents’ income per month), the variables describing the aesthetic properties of roadscape are ordinal (rank), and the variables describing the quantity of car accidents on the researched roads are scale. therefore, the kendall’s tau_b and spearman’s correlation coefficients were counted. kendall’s tau-b correlation coefficient is used to measure the association between two measured quantities. kendall’s tau-b, unlike tau-a, makes adjustments for ties and is suitable for square tables. in our case we have 15x15 table (according to the number of variables), thereby the table is square. values of kendall’s aesthetics and safety of road landscape: are they related? 24 electrical transmission lines etc. are called here as visual disorder. the scholar carried out the research of simulation of drivers’ behavior at day time. the result of her research revealed that visual disorder in road landscape decrease drivers’ attention while driving and negatively affect safety on the roads. h. antonson with a group of researchers (2009) analyzed the reliance of drivers’ behavior and safety on the road landscape type – open, woodlands or mixed. for the research they used the simulator of driving in these types of landscape. then eighteen research participants were asked to answer the questions about their feelings while driving. the research results indicated that in the open landscape the speed of driving is faster, and that road safety depends on the landscape through which road passes. h. drottenborg (2002) analyzed traffic safety and driving behavior in 10 beautiful and 10 ugly traffic environments. the results confirmed that “aesthetically rewarding traffic environments seem to be beneficial for traffic safety”, and that driving speed is lower in beautiful rather than ugly traffic environments due to more stops in beautiful landscape. research in germany demonstrated that the most part (68%) of all the car accidents happen due to the wrong design of road and its landscape, and because of insufficient informativity of road and its landscape. according to küllers’ model of the basic emotional process, “driving behavior is related to the physical environment, other road users, the driving task, the individual factors and own abilities, and to the interaction among them” (drottenborg, 2002). therefore, this research is concentrated on the physical environment, id est the landscape through which the road passes. accordingly, the aim of the research is to identify if there is a relation between landscape aesthetics and safety on lithuanian roads. 2. methods the research objects are the main lithuanian highways which are marked as the european motorway network corridors or the european highways: a1 road vilnius-kaunas-klaipėda (311.40 km), a2 road vilniuspanevėžys (135.92 km), a3 road vilnius-minsk (belarus) (33.99 km), a5 road kaunas-marijampolė-suwalki (poland) (97.06 km), a6 road kaunas-zarasai-daugavpils (latvia) (185.40 km), a8 road panevėžys-aristavasitkūnai (87.86 km), a9 road panevėžys-šiauliai (78.94 km), a10 road panevėžys-pasvalys-bauska (latvia) (66.10 km), a11 road šiauliai-palanga (146.85 km), a12 road riga (latvia)-šiauliai-tauragė-kaliningrad (russia) (186.09 km), a13 road klaipėda-liepaja (latvia) (45.15 km) and a16 road vilnius-prienaimarijampolė (137.51 km) (fig. 1). the total length of the researched roads is 1512.27 km. only the road segments within the lithuanian borders were considered. fig. 1. research objects the research of aesthetic properties of road landscape was conducted in spring 2010 by employing the photo-fixation of road landscape and the qualitative survey (matijošaitienė 2011). selected photos of road landscape were used for the qualitative survey. also aesthetic properties of road landscape were used for the survey and for the analysis of aesthetics and road safety: interesting, natural, visually safe, skittish, beautiful, outstanding, harmonious, sophisticated, relaxing, majestic, pleasant, elements match for surrounding environment, left an intense positive impression, willing to drive on this road. these properties were measured fig. 1. research objects 22 tau_b range from -1 to +1. spearman’s correlation coefficient (spearman’s rho) is a non-parametric measure of statistical dependence between two variables. it assesses how well the relationship between two variables can be described using a monotonic function. if there are no repeated data values, a perfect spearman correlation of +1 or −1 occurs when each of the variables is a perfect monotone function of the other. for instance, when x was increasing y monotonously increases (not necessarily linearly) or decreases. the spearman correlation coefficient is defined between the ranked variables. for the both correlation coefficients the correlation can be: a) very strong when the value is -1 or +1, b) strong when the value is from -1 to -0.7 or from +1 to +0.7, c) moderate when the value is from -0.7 to -0.5 or from +0.7 to +0.5, d) weak when the value is from -0.5 to -0.2 or from +0.5 to 0.2 and e) very weak when the value is from -0.2 to 0 or from +0.2 to 0. a value of 0 indicates the absence of relation. multiple linear regression analysis was applied for the identification of visual characters of road landscape which influence the quantity of car accidents. because all the variables which represents the visual character of road landscape are ordinal (rank) we make the assumption that the intervals between the ranks are equal. the biggest advantage of regression analysis is that regression model (function which connects variables) is composed. regression model is a statistical model which let forecast the values of one variable through the values of other variables. english geneticist f. galton used the term of regression for the first time during his research on the relation between height of children and their parents (čekanavičius 2008). the literature review revealed many cases of application correlation and regression analyses for the research of landscape. for instance, t. daniel (1976) applied correlation analysis for the research of arizona (usa) woodlands. regression analysis is often used for the practical research: for the forecast of election winners for the political purposes, for the identification of consumer opinion about a product or a service, for the research of landscape. p. cook (1995) applied multiple regression and correlation analyses for the analysis of landscape scenery of great plains in the usa, r. clay (2004, 2000) applied correlation, regression and factor analyses for the research of factors which describe californian road scenery. 3. results the characteristics of demographic, financial and marital status of respondents correlate with variables describing road landscape very weakly: the highest correlation coefficients are rtau_b=0.178 (p=0.000<α=0.05) and rs=0.190 (p=0.000<α=0.05) at the significance level of 0.01. these correlations are between the variable outstanding road landscape and the marital status of respondents. therefore, the conclusion is that demographic and financial characteristics of respondents as well as their marital status do not affect respondents’ opinion and assessment of road landscape views. the analysis of the kendall’s tau_b correlations between road landscape describing variables demonstrate that almost all the describing variables correlate to each other. the exception is the variables beautiful and sophisticated – these variables do not correlate at all rtau_b=0.000 (p=0.000<α=0.05). the most of the correlations are moderate, weak and very weak. the strongest correlation (though it is just a strong correlation) is between the variables interesting and skittish rtau_b=0.848 (p=0.000<α=0.05), majestic and left an intense positive impression rtau_b=0.818 (p=0.000<α=0.05), relaxing and willing to drive rtau_b=0.758 (p=0.000<α=0.05), interesting and left an intense positive impression rtau_b=0.727 (p=0.000<α=0.05) all at the significance level of 0.01. there are some opposite very weak correlations between the variables visually safe and elements match for surrounding environment, visually safe and beautiful, outstanding and elements match for surrounding environment, harmonious and sophisticated, sophisticated and elements match for surrounding environment: the better assessment is for one variable the worse assessment is for another variable in the pair (table 1). the higher quantity of car accidents on the road correlates weakly with relaxation rtau_b=-0.303 (p=0.000<α=0.05), visual safety rtau_b=-0.212 (p=0.000<α=0.05), beauty rtau_b=0.364 (p=0.000<α=0.05), sophistication rtau_b=-0.333 (p=0.000<α=0.05) and elements match for surrounding environment rtau_b=0.273 (p=0.000<α=0.05) (table 1). it is interesting that the more road landscape is relaxing, visually safe and sophisticated the less car accidents happen. the analysis of the spearman’s rho correlations between road landscape describing variables demonstrate that almost all the describing variables correlate to each other. the most of the correlations are strong, moderate, weak and very weak. the strong correlation is between the variables skittish and interesting rs=0.951 (p=0.000<α=0.05), majestic and left an intense positive impression rtau_b=0.930 (p=0.000<α=0.05), relaxing and willing to drive rs=0.888 (p=0.000<α=0.05), interesting and left an intense positive impression rtau_b=0.881 (p=0.000<α=0.05), skittish and left an intense positive impression rtau_b=0.853 (p=0.000<α=0.05), skittish and outstanding rtau_b=0.846 (p=0.000<α=0.05), outstanding and left an intense positive impression rtau_b=0.839 (p=0.000<α=0.05), pleasant and beautiful rtau_b=0.813 (p=0.000<α=0.05), interesting and outstanding rtau_b=0.811 (p=0.000<α=0.05), harmonious and elements match for surrounding environment rtau_b=0.804 (p=0.000<α=0.05), beautiful and elements match for surrounding environment rtau_b=0.776 (p=0.000<α=0.05), majestic and willing to drive rtau_b=0.762 (p=0.000<α=0.05), pleasant and skittish rtau_b=0.760 (p=0.000<α=0.05), pleasant and interesting rtau_b=0.760 (p=0.000<α=0.05), majestic and interesting rtau_b=0.741 (p=0.000<α=0.05), majestic and skittish rtau_b=0.734 (p=0.000<α=0.05), relaxing and visually safe rtau_b=0.720 (p=0.000<α=0.05), pleasant and willing to drive rtau_b=0.718 (p=0.000<α=0.05) all at the significance level of 0.01, left an intense positive impression and willing to drive rtau_b=0.706 (p=0.000=α=0.05) at the significance level of 0.05. there are some opposite weak and very weak correlations between the variables visually safe and beautiful, visually safe and elements match for surrounding environment, outstanding and elements match for 23 surrounding environment, harmonious and sophisticated, beautiful and sophisticated, sophisticated and elements match for surrounding environment: the better assessment is for one variable the worse assessment is for another variable in the pair (table 2). the hihger quantity of car accidents on the road correlates weakly with pleasure rtau_b=0.214 (p=0.00<α=0.05), relaxation rtau_b=-0.406 (p=0.00<α=0.05), visual safety rtau_b=-0.315 (p=0.00<α=0.05), harmony rtau_b=0.217 (p=0.00<α=0.05), naturalness kendall’s tau_b correlation coefficient values pleasant relaxing safe skittish interestin outstandi harmoniou majestic natural beautiful sophisticat left posit impr elemen mat willin to drive car accidents pleasant 1.00 .351 .076 .595** .626** .382 .473* .473* .504* .687* .137 .473* .534* .595** .168 relaxing .351 1.00 .545* .152 .303 .242 .394 .515* .030 .091 .364 .394 .242 .758** -.303 safe .076 .545* 1.00 .121 .212 .030 .182 .364 .121 -.182 .394 .364 -.030 .485* -.212 skittish .595** .152 .121 1.00 .848** .667** .091 .576** .455* .394 .424 .697** .121 .394 .061 interestin .626** .303 .212 .848** 1.00 .636** .182 .606** .545* .364 .394 .727** .152 .424 -.030 outstandi .382 .242 .030 .667** .636** 1.00 .061 .545* .182 .303 .394 .667** -.030 .364 .091 harmonio .473* .394 .182 .091 .182 .061 1.00 .091 .273 .394 -.061 .152 .667** .394 .121 majestic .473* .515* .364 .576** .606** .545* .091 1.000 .273 .273 .364 .818** .061 .576** .000 natural .504* .030 .121 .455* .545* .182 .273 .273 1.00 .576** .182 .394 .303 .212 .121 beautiful .687** .091 -.182 .394 .364 .303 .394 .273 .576** 1.00 .000 .273 .606** .333 .364 sophisticat .137 .364 .394 .424 .394 .394 -.061 .364 .182 .000 1.00 .424 -.152 .364 -.333 left posit impr .473* .394 .364 .697** .727** .667** .152 .818** .394 .273 .424 1.00 .061 .576** .000 elements matc .534* .242 -.030 .121 .152 -.030 .667** .061 .303 .606** -.152 .061 1.00 .364 .273 willing to drive .595** .758** .485* .394 .424 .364 .394 .576** .212 .333 .364 .576** .364 1.00 -.061 car accidents .168 -.303 -.212 .061 -.030 .091 .121 .000 .121 .364 -.333 .000 .273 -.061 1.00 **. correlation is significant at the 0.01 level *. correlation is significant at the 0.05 level strong relation moderate relation weak relation very weak relation table 1. kendall’s tau_b correlation coefficient values spearman’s rho correlation coefficient values pleasant relaxing safe skittish interestin outstandi harmoniou majestic natural beautiful sophisticat left posit impr elemen mat willin to drive car accidents pleasant 1.00 .410 .175 .760** .760** .504 .609* .616* .623* .813** .203 .669* .687* .718** .214 relaxing .410 1.00 .720** .259 .399 .308 .455 .615* .126 .077 .497 .531 .203 .888** -.406 safe .175 .720** 1.00 .140 .308 .098 .301 .483 .161 -.203 .573 .510 -.126 .595* -.315 skittish .760** .259 .140 1.00 .951** .,846** .140 .734** .545 .559 .552 .853** .126 .510 .098 interestin .760** .399 .308 .951** 1.00 .811** .294 .741** .615* .510 .594* .881** .168 .573 -.056 outstandi .504 .308 .098 .846** .811** 1.00 .077 .727** .266 .385 .476 .839** -.021 .483 .147 harmonio .609* .455 .301 .140 .294 .077 1.00 .091 .399 .455 -.189 .224 .804** .531 .217 majestic .616* .615* .483 .734** .741** .727** .091 1.000 .385 .399 .559 .930** .056 .762** -.063 natural .623* .126 .161 .545 .615* .266 .399 .385 1.00 .685* .245 .476 .448 .266 .238 beautiful .813** .077 -.203 .559 .510 .385 .455 .399 .685* 1.00 -.014 .406 .776** .399 .476 sophisticat .203 .497 .573 .552 .594* .476 -.189 .559 .245 -.014 1.00 .587* -.378 .448 -.413 left posit impr .669* .531 .510 .853** .881** .839** .224 .930** .476 .406 .587* 1.00 .056 .706* .056 elements matc .687* .203 -.126 .126 .168 -.021 .804** .056 .448 .776** -.378 .056 1.00 .399 .357 willing to drive .718** .888** .594* .510 .573 .483 .531 .762** .266 .399 .448 .706* .399 1.00 -.098 car accidents .214 -.406 -.315 .098 -.056 .147 .217 -.063 .238 .476 -.413 .056 .357 -.098 1.00 **. correlation is significant at the 0.01 level *. correlation is significant at the 0.05 level strong relation moderate relation weak relation very weak relation table 2. spearman’s rho correlation coefficient values 24 rtau_b=0.238 (p=0.00<α=0.05), beauty rtau_b=0.476 (p=0.00<α=0.05), sophistication rtau_b=-0.413 (p=0.00<α=0.05), and elements match for surrounding environment rtau_b=0.357 (p=0.00<α=0.05). it is also interesting that according to the spearman’s rho correlation coefficient values we got the same result as according to the kendall’s tau_b correlation coefficient values: the more road landscape is relaxing, visually safe and sophisticated the less car accidents happen. the application of the multiple linear regression analysis leads to one regression model. the quantity of car accidents is the dependent variable. according to the anova and coefficients tables prepared by the pasw statistics software we find the point estimates for the regression equation. the statistical acceptance of the coefficients of the model (p-value shall not have to exceed α=0.05) was estimated. then the unstandardized coefficient b as well as the variables, which influence the quantity of car accidents were identified. quantity of car accidents = -33.93 + + 40.98*beautiful –33.05*interesting + + 32.78 * willing to drive – – 29.97 * elements match for surrounding environment – – 19.11*relaxing + 14.8*natural + 8.27*harmonious – – 8.2*sophisticated + 7.11*majestic – 1*visually safe (1) the linearity of the regression equation is approved (according to anova p=0.000<0.05). the hypothesis that the coefficients are equal to zero was rejected (p=0.000<0.05), it means that the regression lines are suitable for making predictions. 4. discussion values of the both kendall’s tau_b and spearman’s correlation coefficients demonstrate weak or very weak relations between the variable quantity of car accidents and other variables describing aesthetics of road landscape. this could happen due to not very detailed information about aesthetic properties of each road landscape. the collected data on aesthetic properties describe the landscape of the whole road instead of description of separate sections of each road. more over the regression equation explains only 50.3% of the dispersion of all the variables. whereas the other very important factors which influence the quantity of car accidents remain unknown. on other hand, the regression equation contains too many independent variables (10 of 14), and the constant is very high (-33.93). in consideration of these facts, more detailed analysis should be carried out. the landscape of each road has to be divided into separate segments according to the landscape type. then for each segment more detailed aesthetic properties has to be evaluated. finally the data on landscape aesthetics has to be compared with the number and types of car accidents for each segment of the road. also more detailed data on road landscape aesthetic properties will let us create the guidelines for the design of an aesthetic and safe road landscape, and to forecast potentially dangerous (unsafe) places of road landscape. 5. conclusions the results of the correlation analysis (both kendall’s tau_b and spearman’s correlation coefficients evaluated) revealed that the road safety described through the quantity of car accidents is weakly related with some aesthetic properties of road landscape. actually, the more landscape is pleasant, beautiful, harmonious, natural and elements match for surrounding environment the more car accidents happen, and the more road landscape is relaxing, visually safe and sophisticated the less car accidents happen. these aesthetic properties have to be considered by the planners while designing and creation of safe road landscape. according to the multiple linear regression analysis the more landscape is beautiful, willing to drive, natural, harmonious and majestic the more car accidents happen on the road, and the more road landscape is interesting, elements match for surrounding environment, relaxing, sophisticated and visually safe the less car accidents happen on the road. still, the coefficients of the independent variables and the constant are too high, therefore the equation need to be revised in further research. (i. gurauskiene, 2006, eco-design methodology for electrical and electronic equipment industry) acknowledgements the authors acknowledge student research fellowship award from the lithuanian science council, as well as lithuanian road administration under the ministry of transport and communication for the provided information about car accidents on lithuanian roads. references antonson h., mardch s., wiklund m., blomqvist g. 2009. effect of surrounding landscape on driving behavior: a driving simulator study. journal of environmental psychology, 29 (4), 493-502. clay g. r., smidt r. k. 2004. assessing the validity and reliability of descriptor variables used in scenic highway analysis. landscape and urban planning, 66 (4), 239-255. clay g. r., daniel t. c. 2000. scenic landscape assessment: the effects of land management jurisdiction on public perception of scenic beauty. landscape and urban planning, 49 (1-2), 1-13. cook p. s., cable t. t. 1995. the scenic beauty of shelterbelts on the great plains. landscape and urban planning, 32 (1), 63-69. čekanavičius v., murauskas g. 2008. statistika ir jos taikymai 2 [statistics and its application 2]. vilnius, tev. daniel t. c., boster r. s. 1976. measuring landscape esthetics: the scenic beauty estimation method. usda forest. service, rocky mountain forest and range experiment station, research paper rm-167, fort collins. drottenborg h. 2002. are beautiful traffic environments safer than ugly traffic environments? doctoral thesis. lund university: studentlitteratur. available at: http://www.getcited.org/ pub/103430785 (accessed 16 may 2012). edquist, j. 2008. the effects of visual clutter on driving performance. doctoral thesis. monash university. available 25 at: http://www.tml.org/legal_pdf/billboard-study-article.pdf (accessed 16 may 2012). eismo įvykių statistika [transport accident statistics], 2012. lietuvos automobilių kelių direkcija prie susisiekimo ministerijos. available at: http://www.lra.lt/lt.php/eismo_ saugumas/eismo_ivykiu_statistika/27 (accessed 16 may 2012). i-15 landscape and aesthetics corridor plan. 2005. nevada dot. available at: http://www.ndotprojectneon.com/feis/i-15_ landscape_corridor_plan.pdf. (accessed 16 may 2012). matijošaitienė, i. 2011. automobilių kelių hedonomiško kraštovaizdžio formavimo principai. daktaro disertacija [the principles of formation of hedonomic road landscape. doctoral thesis]. kaunas: technologija. matijošaitienė, i., stankevičė, i. 2011. hedonomic roadscapes in the context of urban sprawl. the scientific journal of riga technical university, 5, 70-76. road landscape manual. version 1. 1997. queensland government, department of main roads. available at: http:// www.tmr.qld.gov.au/business-and-industry/technicalstandards-and-publications/road-landscape-manual.aspx. (accessed 16 may 2012). transport accident statistics, 2012. european commision eurostat. available at: http://epp.eurostat.ec.europa.eu/statistics_ explained/index.php/transport_accident_statistics. (accessed 16 may 2012). received 2012 05 14 accepted after revision 2012 09 03 irina matijošaitinė – lecturer at kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management. main research areas: road and urban landscape, space syntax, kansei engineering, hedonomics, ergonomics, statistics. address: kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. tel.: +370 606 88819 e-mail: irina.matijosaitiene@ktu.lt kristina navickaitė – bachelor student at kaunas university of technology, faculty of civil engineering and architecture. main research areas: urban crime, road landscape. address: kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. tel.: +370 624 39155 e-mail: kristina.navickaite.fsa.statius@gmail.com 61 journal of sustainable architecture and civil engineering 2019/1/24 *corresponding author: kristo.kalbe@taltech.ee influence of window details on the energy performance of an nzeb received 2018/12/11 accepted after revision 2019/02/12 journal of sustainable architecture and civil engineering vol. 1 / no. 24 / 2019 pp. 61-70 doi 10.5755/j01.sace.24.1.22052 influence of window details on the energy performance of an nzeb jsace 1/24 http://dx.doi.org/10.5755/j01.sace.24.1.22052 kristo kalbe*, targo kalamees tallinn university of technology, department of civil engineering and architecture, nearly zero energy buildings research group, ehitajate tee 5, tallinn 19086, estonia introduction one of the largest sources of heat loss in buildings are the windows. however, windows are also important to increase solar heat gain and provide daylight. it is necessary to understand how window details influence the energy performance of very energy efficient houses. this is valuable information for the design decision making process and may lead to further research or product development. this paper examines the influence of window frame thermal transmittance, window frame width and window installation depth on the energy demand of the building. a single-family prefabricated timber nzeb located in estonia was used as a reference building for this study. the results show that decreasing the thermal transmittance and width of the window frame have a remarkable effect on the energy demand of the nzeb (a variation of 42% and 25% respectively). the effect of optimising window installation depth is insignificant (ca 3% variation of heat demand on most of the window placement range and up to 10% of increase in heat demand when comparing the optimal placement to the least effective one). however, it can further improve the energy performance. keywords: energy performance of buildings, nzeb, timber construction, windows, window installation optimisation. it is generally known that buildings account for the largest amount of energy consumption (directive 2010/31/eu) and thus methods to reduce the energy demand of buildings are recommended. previous studies indicate that a large part of the heat loss in buildings occurs through the windows (grynning et al. 2011). the energy balance of a window and the effect of window properties on the energy demand of a building is a complex interaction of a large array of parameters (grynning et al. 2013). it is stated that when designing passive houses, a common technique is to let a large window area face south and to use small windows facing north to minimise the heat losses through the windows (persson et al. 2006). large windows towards the south help to increase the availability of solar heat gain. as stated by winkler et al. (2017), the solar energy gains are among the most important aspects in the design of very low energy buildings like passive houses. therefore, it is reasonable to research the possibilities of reducing the heat loss through windows or increase the solar gain. as stated by sadineni et al. (2011), there have been significant advances in glazing technologies and as brought out by cuce and riffat (2015), triple glazed low-e glazing can already have a thermal transmittance of only 0.28 w/(m2∙ k), which is nearing the recommended thermal transmittance journal of sustainable architecture and civil engineering 2019/1/24 62 value of 0.15 w/(m2∙ k) for passive house walls (feist et al. 2005). there are also various state-ofthe art glazing technologies such as aerogel, vacuum and switchable reflective or suspended film glazing, which can further improve the energy efficiency of glazing (sadineni et al. 2011). marino et al. (2017) stated that there have been numerous studies about the influence of fenestration on the building energy performance. there have been studies about the window-to-wall ratio and glazing properties (for example bülow-hübe 2001, persson, roos, and wall 2006, leskovar and premrov 2011, ihm et al. 2012, susorova et al. 2013, harmati and magyar 2015). but the effect of window frame parameters is still less studied. it is necessary to understand whether the influence of window frames is significant in very efficient houses. this is valuable information for the design decision making process and may lead to further research or product development. in a recent study, misiopecki et al. (2018) investigated the window installation linear thermal transmittance (ltt) in various window installation methods and positions and found that the variation of the ltt is significant, but there was no further research on the effect of ltt on the overall energy demand nor on the effect of window position to the shading and thus on the availability of solar gains. this study determines the influence of window frame details and the window installation depth on the energy demand of the building. two parameters of the window frame were further examined – the window frame thermal transmittance and the width of the window frame. additionally, an optimisation task was carried out to determine the influence of the window installation depth (influenced by the ltt and solar gain through the windows). it was hypothesised that the impact of window frame properties is significant on the energy balance of the nzeb. a single-family prefabricated timber nzeb located in estonia was used as a reference building for this study. energy balance simulations the energy balance simulations were done using the passive house planning package phpp (passive house institute 2013), which utilises the simplified quasi-steady-state monthly met hod specified in iso 13790:2008. the phpp software has been validated with real-world projects within the cepheus project and proved to be an accurate tool for energy balance simulations for passive house level buildings (schnieders and hermelink 2006). additionally – the phpp software allows detailed input of window reveal and overhang shading data, as well as the input of window frame installation ltt values for each of the window sides. the detailed shading data input allows the examination of the effect of window placement on the solar heat gains and thus on the heat demand. the phpp user manual (passive house institute 2013) states that the algorithms used for the calculation are derived from dynamic building simulations (feist 1998, feist et al. 1998). the climate data used for the calculations is in accordance to the estonian test reference year for energy calculations (kalamees and kurnitski 2006). all of the other boundary conditions are as required in the estonian regulation of methodology for calculating the energy performance of buildings (rt i 19.01.2018; 7). for the annual heat demand, the monthly values are added up, which are found by the following equation (eq. 1.). marino et al. (2017) stated that there have been numerous studies about the influence of fenestration on the building energy performance. there have been studies about the window-to-wall ratio and glazing properties (for example bülow-hübe 2001, persson, roos, and wall 2006, leskovar and premrov 2011, ihm et al. 2012, susorova et al. 2013, harmati and magyar 2015). but the effect of window frame parameters is still less studied. it is necessary to understand whether the influence of window frames is significant in very efficient houses. this is valuable information for the design decision making process and may lead to further research or product development. in a recent study, misiopecki et al. (2018) investigated the window installation linear thermal transmittance (ltt) in various window installation methods and positions and found that the variation of the ltt is significant, but there was no further research on the effect of ltt on the overall energy demand nor on the effect of window position to the shading and thus on the availability of solar gains. this study determines the influence of window frame details and the window installation depth on the energy demand of the building. two parameters of the window frame were further examined – the window frame thermal transmittance and the width of the window frame. additionally, an optimisation task was carried out to determine the influence of the window installation depth (influenced by the ltt and solar gain through the windows). it was hypothesised that the impact of window frame properties is significant on the energy balance of the nzeb. a single-family prefabricated timber nzeb located in estonia was used as a reference building for this study. 2. methods 2.1. energy balance simulations the energy balance simulations were done using the passive house planning package phpp (passive house institute 2013), which utilises the simplified quasi-steady-state monthly method specified in iso 13790:2008. the phpp software has been validated with real-world projects within the cepheus project and proved to be an accurate tool for energy balance simulations for passive house level buildings (schnieders and hermelink 2006). additionally – the phpp software allows detailed input of window reveal and overhang shading data, as well as the input of window frame installation ltt values for each of the window sides. the detailed shading data input allows the examination of the effect of window placement on the solar heat gains and thus on the heat demand. the phpp user manual (passive house institute 2013) states that the algorithms used for the calculation are derived from dynamic building simulations (feist 1998, feist et al. 1998). the climate data used for the calculations is in accordance to the estonian test reference year for energy calculations (kalamees and kurnitski 2006). all of the other boundary conditions are as required in the estonian regulation of methodology for calculating the energy performance of buildings (rt i 19.01.2018; 7). for the annual heat demand, the monthly values are added up, which are found by the following equation (eq. 1.). 𝑄𝑄� = 𝑄𝑄� + 𝑄𝑄� − 𝜂𝜂 𝜂 �𝑄𝑄� + 𝑄𝑄� � (1) where: qh = heat demand, kwh/a; qt = total transmission losses (the values for each building element are summed), kwh/a; qv = ventilation losses, kwh/a; qs = solar heat gains, kwh/a; qi = internal heat gains, kwh/a; η = gain utilisation factor. qt and qs change when the window parameters are changed. qt can be found by the average thermal transmittance of the whole building envelope or as a sum of the specific transmission losses of all the (1) where: qh = heat demand, kwh/a; qt = total transmission losses (the values for each building element are summed), kwh/a; qv = ventilation losses, kwh/a; qs = solar heat gains, kwh/a; qi = internal heat gains, kwh/a; η = gain utilisation factor. qt and qs change when the window parameters are changed. qt can be found by the average thermal transmittance of the whole building envelope or as a sum of the specific transmission methods 63 journal of sustainable architecture and civil engineering 2019/1/24 losses of all the building envelope elements. by only changing the window frame parameters, the transmission losses of all the other building elements remain the same. therefore, the method of summing the specific transmission losses for each element is more useful here. the equation for transmission losses for one building envelope element is as follows (eq. 2.). building envelope elements. by only changing the window frame parameters, the transmission losses of all the other building elements remain the same. therefore, the method of summing the specific transmission losses for each element is more useful here. the equation for transmission losses for one building envelope element is as follows (eq. 2.). 𝑄𝑄� = 𝐴𝐴𝐴 𝐴 𝐴𝐴 𝐴 𝐴𝐴� 𝐴 𝐺𝐺� (2) where: a = area of the building envelope element (e.g. the window frame), m2; u = thermal transmittance coefficient of the building element (e.g. the thermal transmittance of the window frame with the installation thermal bridge effect included), w/(m2k); ft = temperature-correction factor; gt = heating degree hours, kkh/a. by changing the window frame dimensions, the area of the transparent building elements or window glazing is changed, and the shading reduction factor is changed slightly. by changing the window frame placement in the walls, the change of shading reduction factor is more pronounced. the following equation (eq. 3.) shows how the glazing area or reduction factor influence the amount of solar heat gains. 𝑄𝑄� = 𝑟𝑟 𝐴 𝑟𝑟 𝐴 𝐴𝐴 𝐴 𝐺𝐺 (3) where: r = reduction factor for shading, dirt and non-perpendicular incident radiation; g = shgc – total solar energy transmittance value; a = total area of the transparent building elements, m2; g = global solar irradiation as an average for the specific period, kwh/(m2a). 2.2. two-dimensional heat transfer simulations and temperature factor calculation in order to determine the ltt of the window installation junctions, lbnl therm 7.6 was used. it is a two-dimensional conduction heat transfer analysis tool based on finite-element method. the computational method is described more in depth in the therm 7 simulation manual (lbnl 2017). the simulation was performed according to methods, conditions and assumptions specified in iso 10211:2017, iso 10077-1:2017, iso 10077-2:2017 and iso 6946:2017. the ltt or psi (), w/(mk)), for the window installation is found by the following equation (eq. 4.). 𝛹𝛹 = 𝛹𝛹�� − 𝐴𝐴�� 𝐴 𝑙𝑙�� − 𝐴𝐴� 𝐴 𝑙𝑙� (4)𝐴 where: l2d = thermal coupling coefficient from the 2d simulation of the window installation junction, w/(mk); uew = thermal transmittance of the exterior wall in the model, w/(m2k); lew = length of the exterior wall projection in the model, m; uw = thermal transmittance of the window product in the model, w/(m2k); lw = length of the window product projection in the model, m. the heat transfer simulation allows the determination of temperatures throughout the model and calculation of the temperature factor frsi (en iso 13788:2012) by the following equation (eq. 5.). 𝐴𝐴��� =𝐴����������� 𝐴 (5)𝐴 where: tsi = temperature at the internal surface, c; te = outdoor air temperature, c; ti = indoor air temperature, c. (2) where: a = area of the building envelope element (e.g. the window frame), m2; u = thermal transmittance coefficient of the building element (e.g. the thermal transmittance of the window frame with the installation thermal bridge effect included), w/(m2∙ k); ft = temperature-correction factor; gt = heating degree hours, kkh/a. by changing the window frame dimensions, the area of the transparent building elements or window glazing is changed, and the shading reduction factor is changed slightly. by changing the window frame placement in the walls, the change of shading reduction factor is more pronounced. the following equation (eq. 3.) shows how the glazing area or reduction factor influence the amount of solar heat gains. building envelope elements. by only changing the window frame parameters, the transmission losses of all the other building elements remain the same. therefore, the method of summing the specific transmission losses for each element is more useful here. the equation for transmission losses for one building envelope element is as follows (eq. 2.). 𝑄𝑄� = 𝐴𝐴𝐴 𝐴 𝐴𝐴 𝐴 𝐴𝐴� 𝐴 𝐺𝐺� (2) where: a = area of the building envelope element (e.g. the window frame), m2; u = thermal transmittance coefficient of the building element (e.g. the thermal transmittance of the window frame with the installation thermal bridge effect included), w/(m2k); ft = temperature-correction factor; gt = heating degree hours, kkh/a. by changing the window frame dimensions, the area of the transparent building elements or window glazing is changed, and the shading reduction factor is changed slightly. by changing the window frame placement in the walls, the change of shading reduction factor is more pronounced. the following equation (eq. 3.) shows how the glazing area or reduction factor influence the amount of solar heat gains. 𝑄𝑄� = 𝑟𝑟 𝐴 𝑟𝑟 𝐴 𝐴𝐴 𝐴 𝐺𝐺 (3) where: r = reduction factor for shading, dirt and non-perpendicular incident radiation; g = shgc – total solar energy transmittance value; a = total area of the transparent building elements, m2; g = global solar irradiation as an average for the specific period, kwh/(m2a). 2.2. two-dimensional heat transfer simulations and temperature factor calculation in order to determine the ltt of the window installation junctions, lbnl therm 7.6 was used. it is a two-dimensional conduction heat transfer analysis tool based on finite-element method. the computational method is described more in depth in the therm 7 simulation manual (lbnl 2017). the simulation was performed according to methods, conditions and assumptions specified in iso 10211:2017, iso 10077-1:2017, iso 10077-2:2017 and iso 6946:2017. the ltt or psi (), w/(mk)), for the window installation is found by the following equation (eq. 4.). 𝛹𝛹 = 𝛹𝛹�� − 𝐴𝐴�� 𝐴 𝑙𝑙�� − 𝐴𝐴� 𝐴 𝑙𝑙� (4)𝐴 where: l2d = thermal coupling coefficient from the 2d simulation of the window installation junction, w/(mk); uew = thermal transmittance of the exterior wall in the model, w/(m2k); lew = length of the exterior wall projection in the model, m; uw = thermal transmittance of the window product in the model, w/(m2k); lw = length of the window product projection in the model, m. the heat transfer simulation allows the determination of temperatures throughout the model and calculation of the temperature factor frsi (en iso 13788:2012) by the following equation (eq. 5.). 𝐴𝐴��� =𝐴����������� 𝐴 (5)𝐴 where: tsi = temperature at the internal surface, c; te = outdoor air temperature, c; ti = indoor air temperature, c. (3) where: r = reduction factor for shading, dirt and non-perpendicular incident radiation; g = shgc – total solar energy transmittance value; a = total area of the transparent building elements, m2; g = global solar irradiation as an average for the specific period, kwh/(m2∙ a). two-dimensional heat transfer simulations and temperature factor calculation in order to determine the ltt of the window installation junctions, lbnl therm 7.6 was used. it is a two-dimensional conduction heat transfer analysis tool based on finite-element method. the computational method is described more in depth in the therm 7 simulation manual (lbnl 2017). the simulation was performed according to methods, conditions and assumptions specified in iso 10211:2017, iso 10077-1:2017, iso 10077-2:2017 and iso 6946:2017. the ltt or psi (ψ), w/(m∙ k), for the window installation is found by the following equation (eq. 4.). building envelope elements. by only changing the window frame parameters, the transmission losses of all the other building elements remain the same. therefore, the method of summing the specific transmission losses for each element is more useful here. the equation for transmission losses for one building envelope element is as follows (eq. 2.). 𝑄𝑄� = 𝐴𝐴𝐴 𝐴 𝐴𝐴 𝐴 𝐴𝐴� 𝐴 𝐺𝐺� (2) where: a = area of the building envelope element (e.g. the window frame), m2; u = thermal transmittance coefficient of the building element (e.g. the thermal transmittance of the window frame with the installation thermal bridge effect included), w/(m2k); ft = temperature-correction factor; gt = heating degree hours, kkh/a. by changing the window frame dimensions, the area of the transparent building elements or window glazing is changed, and the shading reduction factor is changed slightly. by changing the window frame placement in the walls, the change of shading reduction factor is more pronounced. the following equation (eq. 3.) shows how the glazing area or reduction factor influence the amount of solar heat gains. 𝑄𝑄� = 𝑟𝑟 𝐴 𝑟𝑟 𝐴 𝐴𝐴 𝐴 𝐺𝐺 (3) where: r = reduction factor for shading, dirt and non-perpendicular incident radiation; g = shgc – total solar energy transmittance value; a = total area of the transparent building elements, m2; g = global solar irradiation as an average for the specific period, kwh/(m2a). 2.2. two-dimensional heat transfer simulations and temperature factor calculation in order to determine the ltt of the window installation junctions, lbnl therm 7.6 was used. it is a two-dimensional conduction heat transfer analysis tool based on finite-element method. the computational method is described more in depth in the therm 7 simulation manual (lbnl 2017). the simulation was performed according to methods, conditions and assumptions specified in iso 10211:2017, iso 10077-1:2017, iso 10077-2:2017 and iso 6946:2017. the ltt or psi (), w/(mk)), for the window installation is found by the following equation (eq. 4.). 𝛹𝛹 = 𝛹𝛹�� − 𝐴𝐴�� 𝐴 𝑙𝑙�� − 𝐴𝐴� 𝐴 𝑙𝑙� (4)𝐴 where: l2d = thermal coupling coefficient from the 2d simulation of the window installation junction, w/(mk); uew = thermal transmittance of the exterior wall in the model, w/(m2k); lew = length of the exterior wall projection in the model, m; uw = thermal transmittance of the window product in the model, w/(m2k); lw = length of the window product projection in the model, m. the heat transfer simulation allows the determination of temperatures throughout the model and calculation of the temperature factor frsi (en iso 13788:2012) by the following equation (eq. 5.). 𝐴𝐴��� =𝐴����������� 𝐴 (5)𝐴 where: tsi = temperature at the internal surface, c; te = outdoor air temperature, c; ti = indoor air temperature, c. (4) where: l2d = thermal coupling coefficient from the 2d simulation of the window installation junction, w/(m∙ k); uew = thermal transmittance of the exterior wall in the model, w/(m 2∙ k); lew = length of the exterior wall projection in the model, m; uw = thermal transmittance of the window product in the model, w/(m2∙ k); lw = length of the window product projection in the model, m. the heat transfer simulation allows the determination of temperatures throughout the model and calculation of the temperature factor frsi (en iso 13788:2012) by the following equation (eq. 5.). building envelope elements. by only changing the window frame parameters, the transmission losses of all the other building elements remain the same. therefore, the method of summing the specific transmission losses for each element is more useful here. the equation for transmission losses for one building envelope element is as follows (eq. 2.). 𝑄𝑄� = 𝐴𝐴𝐴 𝐴 𝐴𝐴 𝐴 𝐴𝐴� 𝐴 𝐺𝐺� (2) where: a = area of the building envelope element (e.g. the window frame), m2; u = thermal transmittance coefficient of the building element (e.g. the thermal transmittance of the window frame with the installation thermal bridge effect included), w/(m2k); ft = temperature-correction factor; gt = heating degree hours, kkh/a. by changing the window frame dimensions, the area of the transparent building elements or window glazing is changed, and the shading reduction factor is changed slightly. by changing the window frame placement in the walls, the change of shading reduction factor is more pronounced. the following equation (eq. 3.) shows how the glazing area or reduction factor influence the amount of solar heat gains. 𝑄𝑄� = 𝑟𝑟 𝐴 𝑟𝑟 𝐴 𝐴𝐴 𝐴 𝐺𝐺 (3) where: r = reduction factor for shading, dirt and non-perpendicular incident radiation; g = shgc – total solar energy transmittance value; a = total area of the transparent building elements, m2; g = global solar irradiation as an average for the specific period, kwh/(m2a). 2.2. two-dimensional heat transfer simulations and temperature factor calculation in order to determine the ltt of the window installation junctions, lbnl therm 7.6 was used. it is a two-dimensional conduction heat transfer analysis tool based on finite-element method. the computational method is described more in depth in the therm 7 simulation manual (lbnl 2017). the simulation was performed according to methods, conditions and assumptions specified in iso 10211:2017, iso 10077-1:2017, iso 10077-2:2017 and iso 6946:2017. the ltt or psi (), w/(mk)), for the window installation is found by the following equation (eq. 4.). 𝛹𝛹 = 𝛹𝛹�� − 𝐴𝐴�� 𝐴 𝑙𝑙�� − 𝐴𝐴� 𝐴 𝑙𝑙� (4)𝐴 where: l2d = thermal coupling coefficient from the 2d simulation of the window installation junction, w/(mk); uew = thermal transmittance of the exterior wall in the model, w/(m2k); lew = length of the exterior wall projection in the model, m; uw = thermal transmittance of the window product in the model, w/(m2k); lw = length of the window product projection in the model, m. the heat transfer simulation allows the determination of temperatures throughout the model and calculation of the temperature factor frsi (en iso 13788:2012) by the following equation (eq. 5.). 𝐴𝐴��� =𝐴����������� 𝐴 (5)𝐴 where: tsi = temperature at the internal surface, c; te = outdoor air temperature, c; ti = indoor air temperature, c. (5) where: tsi = temperature at the internal surface, °c; te = outdoor air temperature, °c; ti = indoor air temperature, °c. to avoid mould growth on the thermal bridges, the minimal spot temperature factor should be frsi ≥ 0.80 in the estonian climate (kalamees 2006). reference building as built (nzeb) and as a low energy building (leb) the reference building size and floor plan (fig. 1) are representative to the average estonian single-family house. the total heated area of the reference building is 148 m2. the building is designed journal of sustainable architecture and civil engineering 2019/1/24 64 according to the principles of the passive house method (feist et al. 2005b) and, with the added photovoltaic system, it is also a nearly zero energy building (nzeb) according to the local regulations (rt i 05.06.2015; 15.). the building is located in the inland area of the estonian climate (kalamees and kurnitski 2006). a mechanical ventilation system with heat recovery rate of up to 93% is utilised. the house is built with prefabricated timber elements with 500 mm of blown cellulose insulation in the walls (u = 0.08 w/(m2∙ k)) and 600 mm of blown cellulose insulation on the roof (u = 0.06 w/(m2∙ k)). the insulated timber elements are mounted on a concrete slab with 500 mm of xps insulation underneath (u = 0.06 w/(m2∙ k)). fig. 1 reference building view from southeast (left) and the firstfloor plan (right) to avoid mould growth on the thermal bridges, the minimal spot temperature factor should be frsi ≥ 0.80 in the estonian climate (kalamees 2006). 2.3. reference building as built (nzeb) and as a low energy building (leb) the reference building size and floor plan (fig. 1) are representative to the average estonian singlefamily house. the total heated area of the reference building is 148 m2. the building is designed according to the principles of the passive house method (feist et al. 2005b) and, with the added photovoltaic system, it is also a nearly zero energy building (nzeb) according to the local regulations (rt i 05.06.2015; 15.). the building is located in the inland area of the estonian climate (kalamees and kurnitski 2006). a mechanical ventilation system with heat recovery rate of up to 93% is utilised. the house is built with prefabricated timber elements with 500 mm of blown cellulose insulation in the walls (u = 0.08 w/(m2k)) and 600 mm of blown cellulose insulation on the roof (u = 0.06 w/(m2k)). the insulated timber elements are mounted on a concrete slab with 500 mm of xps insulation underneath (u = 0.06 w/(m2k)). the windows in the reference building have wood-aluminium frames and triple low-e glazing. further details of the installed windows are in table 1. all the given information is also considered in the energy balance calculations. the specific wood-aluminium window frames installed in the building are developed to be used in very efficient houses and have wood fibre insulation covering on the timber frame which in turn is suitable to be covered with additional insulation (for example the exterior wall insulation or wind barrier). in the reference building the window frames were covered with additional wood fibre insulation. see figure 2 for the detailed drawing of a typical junction. about 70% of the window area is facing towards the south – this is a common practice with energy efficient buildings designed for the northern hemisphere. furthermore – the windows have few divisions to maximise the solar gain and minimise the heat loss through the window frames. fig. 1. reference building view from southeast (left) and the first-floor plan (right). table 1. reference building operable and fixed window frame parameters. window type operable fixed frame section threshold bottom top lateral transom bottom top lateral transom frame width (mm) 76 86 86 86 110 86 86 86 110 the windows in the reference building have wood-aluminium frames and triple low-e glazing. further details of the installed windows are in table 1. all the given information is also considered in the energy balance calculations. table 1 reference building operable and fixed window frame parameters window type operable fixed frame section threshold bottom top lateral transom bottom top lateral transom frame width (mm) 76 86 86 86 110 86 86 86 110 frame thermal transmittance (w/(m2∙ k)) 1.00 0.89 0.68 0.68 0.96 0.69 0.52 0.52 0.79 the specific wood-aluminium window frames installed in the building are developed to be used in very efficient houses and have wood fibre insulation covering on the timber frame which in turn is suitable to be covered with additional insulation (for example the exterior wall insulation or wind barrier). in the reference building the window frames were covered with additional wood fibre insulation. see fig. 2 for the detailed drawing of a typical junction. about 70% of the window area is facing towards the south – this is a common practice with energy efficient buildings designed for the northern hemisphere. furthermore – the windows have few divisions to maximise the solar gain and minimise the heat loss through the window frames. an additional model of the reference building was proposed to determine whether the effect of window frame parameters and the installation depth is specific to very efficient buildings. thus, a model with reduced energy performance was proposed, with wall, roof and floor construction corresponding to typical prefabricated low-energy buildings (leb) in estonia. see table 2 for the respective thermal transmittances. everything else was left unchanged. the proposed wall construction for the leb has an insulation layer of 195+45 mm as opposed to the wall construction of the 65 journal of sustainable architecture and civil engineering 2019/1/24 built nzeb which has 500 mm of insulation. the choice of the thinner wall also allows studying the effect of the window installation on different wall thicknesses. in fig. 2 there is also the typical window installation junction of the leb. fig. 2 typical window installation junctions for the nzeb (left) and the leb (right) table 2 thermal envelope parameters of the nzeb and leb versions of the reference building frame thermal transmittance (w/(m2k)) 1.00 0.89 0.68 0.68 0.96 0.69 0.52 0.52 0.79 an additional model of the reference building was proposed to determine whether the effect of window frame parameters and the installation depth is specific to very efficient buildings. thus, a model with reduced energy performance was proposed, with wall, roof and floor construction corresponding to typical prefabricated low-energy buildings (leb) in estonia. see table 2 for the respective thermal transmittances. everything else was left unchanged. the proposed wall construction for the leb has an insulation layer of 195+45 mm as opposed to the wall construction of the built nzeb which has 500 mm of insulation. the choice of the thinner wall also allows studying the effect of the window installation on different wall thicknesses. in figure 2 there is also the typical window installation junction of the leb. table 2. thermal envelope parameters of the nzeb and leb versions of the reference building. part of the thermal envelope thermal transmittance (w/(m2k)) reference building as built (nzeb) reference building as leb external wall 0.08 0.16 roof 0.06 0.07 floor slab 0.06 0.17 fig. 2. typical window installation junctions for the nzeb (left) and the leb (right). 2.4. analysis of the effect of window frame properties for determining the influence of the thermal transmittance of the window frames, a hypothetical window frame with homogeneous properties was proposed. the projected width of the frame section (marked as “w” in figure 2) of the window frame was chosen to be 11 cm, which is a common value among contemporary windows. only the uf value was incrementally changed from 0.5 w/(m2k) to 1.4 w/(m2k) in the energy balance simulations. everything else was left unchanged. for the sensitivity analysis of the influence of window frame width, w (see fig. 2), to the energy balance a similar approach was used. again – a hypothetical homogenous window frame was used in the simulations, but the uf value was left unchanged at 0.8 w/(m2k), corresponding to good thermal quality and the frame width (w) was incrementally changed from 5 to 14 cm. in relation to that the glazing area and the shading reduction factor was changed. the analysis was done for both the nzeb and leb version of the reference building. part of the thermal envelope thermal transmittance (w/(m2∙ k)) reference building as built (nzeb) reference building as leb external wall 0.08 0.16 roof 0.06 0.07 floor slab 0.06 0.17 analysis of the effect of window frame properties for determining the influence of the thermal transmittance of the window frames, a hypothetical window frame with homogeneous properties was proposed. the projected width of the frame section (marked as “w” in fig. 2) of the window frame was chosen to be 11 cm, which is a common value among contemporary windows. only the uf value was incrementally changed from 0.5 w/(m 2∙ k) to 1.4 w/(m2∙ k) in the energy balance simulations. everything else was left unchanged. for the sensitivity analysis of the influence of window frame width, w (see fig. 2), to the energy balance a similar approach was used. again – a hypothetical homogenous window frame was used in the simulations, but the uf value was left unchanged at 0.8 w/(m 2∙ k), corresponding to good thermal quality and the frame width (w) was incrementally changed from 5 to 14 cm. in relation to that the glazing area and the shading reduction factor was changed. the analysis was done for both the nzeb and leb version of the reference building. analysis of the effect of window installation to determine the influence of window installation depth, a series of simulations were done on the basis of the reference building both as nzeb and as leb. the window frame placement (the distance from the window frame midpoint to the façade plane, marked as “d” in fig. 2) was incrementally changed in 14 steps from the outer edge to the inner edge of the window reveal. the steps were 30 mm for the nzeb and 10 mm for the leb version of the building. for each step, a new energy balance calculation was done, considering the changed shading situation and changed window installation thermal bridge. thus, heat-transfer simulations were carried out to determine the ltt or psi values and temperature factor or frsi values for the top, side and bottom section of the window installation for each of the steps and for both versions of the building. on fig. 3 there is an excerpt of the simulated models for the top section of the window installation for both building versions in the extreme and middle positions of the window. on each of the positions depicted, there is also the corresponding window frame midpoint distance from the façade plane (d). as seen – for the nzeb version the distance variation is 39 cm from the outer extreme position to the inner extreme position and 13 cm for the leb version. thus, the innermost position on the nzeb version is more shaded than on the leb version. journal of sustainable architecture and civil engineering 2019/1/24 66 in fig. 4 there is the annual energy balance of the reference building as built. it is observed that the heat loss through windows constitutes a large part of the total heat loss. however, the solar heat through windows contributes a large amount of the gains also and thereof is an important factor. fig. 3 excerpt of the therm models simulated to find window installation ltt values 2.5. analysis of the effect of window installation to determine the influence of window installation depth, a series of simulations were done on the basis of the reference building both as nzeb and as leb. the window frame placement (the distance from the window frame midpoint to the façade plane, marked as “d” in figure 2) was incrementally changed in 14 steps from the outer edge to the inner edge of the window reveal. the steps were 30 mm for the nzeb and 10 mm for the leb version of the building. for each step, a new energy balance calculation was done, considering the changed shading situation and changed window installation thermal bridge. thus, heat-transfer simulations were carried out to determine the ltt or psi values and temperature factor or frsi values for the top, side and bottom section of the window installation for each of the steps and for both versions of the building. on figure 3 there is an excerpt of the simulated models for the top section of the window installation for both building versions in the extreme and middle positions of the window. on each of the positions depicted, there is also the corresponding window frame midpoint distance from the façade plane (d). as seen – for the nzeb version the distance variation is 39 cm from the outer extreme position to the inner extreme position and 13 cm for the leb version. thus, the innermost position on the nzeb version is more shaded than on the leb version. fig. 3. excerpt of the therm models simulated to find window installation ltt values. 3. results in figure 4 there is the annual energy balance of the reference building as built. it is observed that the heat loss through windows constitutes a large part of the total heat loss. however, the solar heat through windows contributes a large amount of the gains also and thereof is an important factor. results fig. 4 energy balance of the reference building as built (nzeb level). heat losses are on the left and gains on the right fig. 4. energy balance of the reference building as built (nzeb level). heat losses are on the left and gains on the right. increasing the window frame thermal transmittance from 0.5 w/(m2k) to 1.4 w/(m2k) increases the net heat demand by 42% on the nzeb version of the reference building (from 16.3 to 23.1 kwh/(m2a)) and by 27% on the leb version (from 29,6 to 37,5 kwh/(m2a)). see figure 5 for a graphical representation of the relation. the variation of the window frame width (w) from 5 to 14 cm results in the increase of the net heat demand from 15.8 to 19.8 kwh/(m2a) on the nzeb (increase of 25%) and from 28.2 to 34.0 kwh/(m2a) on the leb (increase of 21%). in figure 5 there is the corresponding relation. fig. 5. the influence of window frame thermal transmittance (left) and the window frame width (right) to the overall net heat demand of the two versions of the reference building. in table 3 there are the average ltt values and the minimum frsi values for each of the simulated positions for the nzeb version of the reference house. the frsi values which meet the minimum increasing the window frame thermal transmittance from 0.5 w/(m2∙ k) to 1.4 w/(m2∙ k) increases the net heat demand by 42% on the nzeb version of the reference building (from 16.3 to 23.1 kwh/ (m2∙ a)) and by 27% on the leb version (from 29,6 to 37,5 kwh/(m2∙ a)). see fig. 5 for a graphical representation of the relation. the variation of the window frame width (w) from 5 to 14 cm results in the increase of the net heat demand from 15.8 to 19.8 kwh/(m2∙ a) on the nzeb (increase of 25%) and from 28.2 to 34.0 kwh/ (m2∙ a) on the leb (increase of 21%). in fig. 5 there is the corresponding relation. fig. 5 the influence of window frame thermal transmittance (left) and the window frame width (right) to the overall net heat demand of the two versions of the reference building fig. 4. energy balance of the reference building as built (nzeb level). heat losses are on the left and gains on the right. increasing the window frame thermal transmittance from 0.5 w/(m2k) to 1.4 w/(m2k) increases the net heat demand by 42% on the nzeb version of the reference building (from 16.3 to 23.1 kwh/(m2a)) and by 27% on the leb version (from 29,6 to 37,5 kwh/(m2a)). see figure 5 for a graphical representation of the relation. the variation of the window frame width (w) from 5 to 14 cm results in the increase of the net heat demand from 15.8 to 19.8 kwh/(m2a) on the nzeb (increase of 25%) and from 28.2 to 34.0 kwh/(m2a) on the leb (increase of 21%). in figure 5 there is the corresponding relation. fig. 5. the influence of window frame thermal transmittance (left) and the window frame width (right) to the overall net heat demand of the two versions of the reference building. in table 3 there are the average ltt values and the minimum frsi values for each of the simulated positions for the nzeb version of the reference house. the frsi values which meet the minimum fig. 4. energy balance of the reference building as built (nzeb level). heat losses are on the left and gains on the right. increasing the window frame thermal transmittance from 0.5 w/(m2k) to 1.4 w/(m2k) increases the net heat demand by 42% on the nzeb version of the reference building (from 16.3 to 23.1 kwh/(m2a)) and by 27% on the leb version (from 29,6 to 37,5 kwh/(m2a)). see figure 5 for a graphical representation of the relation. the variation of the window frame width (w) from 5 to 14 cm results in the increase of the net heat demand from 15.8 to 19.8 kwh/(m2a) on the nzeb (increase of 25%) and from 28.2 to 34.0 kwh/(m2a) on the leb (increase of 21%). in figure 5 there is the corresponding relation. fig. 5. the influence of window frame thermal transmittance (left) and the window frame width (right) to the overall net heat demand of the two versions of the reference building. in table 3 there are the average ltt values and the minimum frsi values for each of the simulated positions for the nzeb version of the reference house. the frsi values which meet the minimum 67 journal of sustainable architecture and civil engineering 2019/1/24 in table 3 there are the average ltt values and the minimum frsi values for each of the simulated positions for the nzeb version of the reference house. the frsi values which meet the minimum requirement in the estonian climate (kalamees 2006) are marked with a light green background. in table 4 there are the corresponding values for the leb version of the house. the lowest frsi values were on the bottom part of the window frame installation on both building versions. for the top and side part of the window installation, the frsi values were above 0.80 for all of the window frame positions and thus were within the accepted limit. in fig. 6 there is a graphical representation of the average ψ values. table 3 average ltt and minimum frsi values for the window installation junctions on the nzeb d, mm & relative installation depth, % 7 0% 10 8% 13 15% 16 23% 19 31% 22 38% 25 46% 28 54% 31 62% 34 69% 37 77% 40 85% 43 92% 47 100% average ltt, w/(m∙ k) 0.047 0.044 0.042 0.040 0.038 0.037 0.036 0.036 0.036 0.037 0.039 0.041 0.044 0.050 frsi bottom installation 0.787 0.790 0.793 0.797 0.800 0.803 0.803 0.807 0.813 0.817 0.827 0.833 0.840 0.823 the shading effect of the window reveal increases, when moving the window frame towards the interior. in fig. 6 there is a chart to describe this effect on both the nzeb and leb version. table 4 average ltt and minimum frsi values for the window installation junctions on the leb d, mm & relative installation depth, % 7 0% 8 8% 9 15% 10 23% 11 31% 12 38% 13 46% 14 54% 15 62% 16 69% 17 77% 18 85% 19 92% 20 100% average ltt w/(m∙k) 0.043 0.039 0.035 0.032 0.031 0.029 0.028 0.028 0.028 0.028 0.029 0.030 0.031 0.033 frsi bottom installation 0.797 0.803 0.807 0.810 0.813 0.817 0.820 0.823 0.827 0.830 0.837 0.840 0.847 0.853 the maximum difference of the average window installation ltt is 0.014 w/(m∙ k) on the nzeb version and 0.015 w/(m∙ k) on the leb version of the reference building. considering the total length of window installation (87.4 m) and the amount of heating degree hours (107,460 kh) from the base model, the maximum saveable energy amount is 131,488 wh or 131.5 kwh per year or 0.89 kwh/(m2∙ a) on the nzeb. as the total amount of heat losses is 56.7 kwh/(m2∙ a), the saveable amount by window frame installation optimisation is about 1.7%. the corresponding amount on the leb is about 1.08 kwh/(m2∙ a) or 1.2% of the total heat loss of 87.2 kwh/(m2∙ a). the possible energy savings from the lower window installation ltt is however counteracted by the fig. 6 the variation of the window installation ltt (left) and the available solar heat gain (right) in relation to the installation depth on both versions of the reference building fig. 6. the variation of the window installation ltt (left) and the available solar heat gain (right) in relation to the installation depth on both versions of the reference building. the maximum difference of the average window installation ltt is 0.014 w/(mk) on the nzeb version and 0.015 w/(mk) on the leb version of the reference building. considering the total length of window installation (87.4 m) and the amount of heating degree hours (107,460 kh) from the base model, the maximum saveable energy amount is 131,488 wh or 131.5 kwh per year or 0.89 kwh/(m2a) on the nzeb. as the total amount of heat losses is 56.7 kwh/(m2a), the saveable amount by window frame installation optimisation is about 1.7%. the corresponding amount on the leb is about 1.08 kwh/(m2a) or 1.2% of the total heat loss of 87.2 kwh/(m2a). the possible energy savings from the lower window installation ltt is however counteracted by the decrease in solar gain. the amount of available solar heat gain decreases by 7.1% on the nzeb and 2.6 % on the leb when the installation depth of windows is changed from the outermost position to the relative depth of 46% (where the lowest ltt occurs). in figure 7 there are graphs for the relation of the overall net heat demand to the window installation depth on both building versions. the points with minimum heat demand are marked with a red line on the figure. the overall net heat demand varies from 16.6 to 18.2 kwh/(m2a) on the nzeb and from 28.6 to 29.4 kwh/(m2a) on the leb. in the case of the nzeb, the variation in heat demand is only about 3% on the relative installation depth range of 0…69% and only on the innermost window position, the difference with the most effective position reaches 10% (mostly due to decreased solar heat gain). on the leb, the variation in heat demand is 3% within the whole installation depth range. fig. 6. the variation of the window installation ltt (left) and the available solar heat gain (right) in relation to the installation depth on both versions of the reference building. the maximum difference of the average window installation ltt is 0.014 w/(mk) on the nzeb version and 0.015 w/(mk) on the leb version of the reference building. considering the total length of window installation (87.4 m) and the amount of heating degree hours (107,460 kh) from the base model, the maximum saveable energy amount is 131,488 wh or 131.5 kwh per year or 0.89 kwh/(m2a) on the nzeb. as the total amount of heat losses is 56.7 kwh/(m2a), the saveable amount by window frame installation optimisation is about 1.7%. the corresponding amount on the leb is about 1.08 kwh/(m2a) or 1.2% of the total heat loss of 87.2 kwh/(m2a). the possible energy savings from the lower window installation ltt is however counteracted by the decrease in solar gain. the amount of available solar heat gain decreases by 7.1% on the nzeb and 2.6 % on the leb when the installation depth of windows is changed from the outermost position to the relative depth of 46% (where the lowest ltt occurs). in figure 7 there are graphs for the relation of the overall net heat demand to the window installation depth on both building versions. the points with minimum heat demand are marked with a red line on the figure. the overall net heat demand varies from 16.6 to 18.2 kwh/(m2a) on the nzeb and from 28.6 to 29.4 kwh/(m2a) on the leb. in the case of the nzeb, the variation in heat demand is only about 3% on the relative installation depth range of 0…69% and only on the innermost window position, the difference with the most effective position reaches 10% (mostly due to decreased solar heat gain). on the leb, the variation in heat demand is 3% within the whole installation depth range. journal of sustainable architecture and civil engineering 2019/1/24 68 decrease in solar gain. the amount of available solar heat gain decreases by 7.1% on the nzeb and 2.6 % on the leb when the installation depth of windows is changed from the outermost position to the relative depth of 46% (where the lowest ltt occurs). in fig. 7 there are graphs for the relation of the overall net heat demand to the window installation depth on both building versions. the points with minimum heat demand are marked with a red line on the figure. the overall net heat demand varies from 16.6 to 18.2 kwh/(m2∙ a) on the nzeb and from 28.6 to 29.4 kwh/(m2∙ a) on the leb. in the case of the nzeb, the variation in heat demand is only about 3% on the relative installation depth range of 0…69% and only on the innermost window position, the difference with the most effective position reaches 10% (mostly due to decreased solar heat gain). on the leb, the variation in heat demand is 3% within the whole installation depth range. fig. 7 the effect of window installation depth on the reference building heat demand (nzeb version on the left and leb version on the right). the red lines mark the optimal installation depths fig. 7. the effect of window installation depth on the reference building heat demand (nzeb version on the left and leb version on the right). the red lines mark the optimal installation depths. 4. discussion the results indicate that the window frame thermal transmittance and its dimensions indeed influence the overall energy balance of the nzeb by a noticeable margin (over 40%). the effect is less significant on the leb, which indicates that the window frames gain more importance in the overall energy balance as the net heat demand of the building decreases. it follows from this that from a design decision making point of view, the actual window frame product is important. moreover – the window frame width is also important – the net heat demand increases over 20% on both the nzeb and leb versions of the building when the frame width is changed from very shallow to slightly larger than regular. thus, it is not advisable to compare window products by only comparing the total thermal transmittance, as the effect of window frame width to solar heat gain is also noticeable. when only considering the net heat demand, the lowest thermal transmittance and the smallest frame dimensions are preferred, but the increased solar gain might also contribute to overheating. thus, further investigation is applicable to determine design decision making recommendations from the overheating point of view and taking both the heat demand and overheating issues into account. nonetheless – this study shows that the window frame product and its properties should be included in detail to the energy performance calculations of nzebs. concerning the window installation ltt, the results are in conjunction with the study by misiopecki et al. (2018). it is observed that the lowest window installation ltt values are achieved for window positions roughly in the centre of the window reveal for both the nzeb and leb. however, this has an insignificant effect on the overall heat demand compared to the influence of window frame thermal transmittance or the influence of the window frame width. furthermore, it is counteracted by the increasing shading effect of the window reveal once the window is positioned deeper into the wall construction. the negative influence of shading is even more pronounced on the nzeb because of its thicker walls. it is apparent that due to the different overall wall thicknesses, the optimal relative installation depth is different on the two versions of the building. however, the distances from the frame midpoint to the façade plane, at which the net heat demand is the lowest, is about the same on both the nzeb and leb. this is because the influence of the solar gain on the overall building energy balance is greater than the influence of window installation ltt. thus, it is preferable to install the windows towards the outside of the wall construction, but in such a way that the temperature factor frsi is within fig. 7. the effect of window installation depth on the reference building heat demand (nzeb version on the left and leb version on the right). the red lines mark the optimal installation depths. 4. discussion the results indicate that the window frame thermal transmittance and its dimensions indeed influence the overall energy balance of the nzeb by a noticeable margin (over 40%). the effect is less significant on the leb, which indicates that the window frames gain more importance in the overall energy balance as the net heat demand of the building decreases. it follows from this that from a design decision making point of view, the actual window frame product is important. moreover – the window frame width is also important – the net heat demand increases over 20% on both the nzeb and leb versions of the building when the frame width is changed from very shallow to slightly larger than regular. thus, it is not advisable to compare window products by only comparing the total thermal transmittance, as the effect of window frame width to solar heat gain is also noticeable. when only considering the net heat demand, the lowest thermal transmittance and the smallest frame dimensions are preferred, but the increased solar gain might also contribute to overheating. thus, further investigation is applicable to determine design decision making recommendations from the overheating point of view and taking both the heat demand and overheating issues into account. nonetheless – this study shows that the window frame product and its properties should be included in detail to the energy performance calculations of nzebs. concerning the window installation ltt, the results are in conjunction with the study by misiopecki et al. (2018). it is observed that the lowest window installation ltt values are achieved for window positions roughly in the centre of the window reveal for both the nzeb and leb. however, this has an insignificant effect on the overall heat demand compared to the influence of window frame thermal transmittance or the influence of the window frame width. furthermore, it is counteracted by the increasing shading effect of the window reveal once the window is positioned deeper into the wall construction. the negative influence of shading is even more pronounced on the nzeb because of its thicker walls. it is apparent that due to the different overall wall thicknesses, the optimal relative installation depth is different on the two versions of the building. however, the distances from the frame midpoint to the façade plane, at which the net heat demand is the lowest, is about the same on both the nzeb and leb. this is because the influence of the solar gain on the overall building energy balance is greater than the influence of window installation ltt. thus, it is preferable to install the windows towards the outside of the wall construction, but in such a way that the temperature factor frsi is within the results indicate that the window frame thermal transmittance and its dimensions indeed influence the overall energy balance of the nzeb by a noticeable margin (over 40%). the effect is less significant on the leb, which indicates that the window frames gain more importance in the overall energy balance as the net heat demand of the building decreases. it follows from this that from a design decision making point of view, the actual window frame product is important. moreover – the window frame width is also important – the net heat demand increases over 20% on both the nzeb and leb versions of the building when the frame width is changed from very shallow to slightly larger than regular. thus, it is not advisable to compare window products by only comparing the total thermal transmittance, as the effect of window frame width to solar heat gain is also noticeable. when only considering the net heat demand, the lowest thermal transmittance and the smallest frame dimensions are preferred, but the increased solar gain might also contribute to overheating. thus, further investigation is applicable to determine design decision making recommendations from the overheating point of view and taking both the heat demand and overheating issues into account. nonetheless – this study shows that the window frame product and its properties should be included in detail to the energy performance calculations of nzebs. concerning the window installation ltt, the results are in conjunction with the study by misiopecki et al. (2018). it is observed that the lowest window installation ltt values are achieved for window positions roughly in the centre of the window reveal for both the nzeb and leb. however, this has an insignificant effect on the overall heat demand compared to the influence of window frame thermal transmittance or the influence of the window frame width. furthermore, it is counteracted by the increasing shading effect of the window reveal once the window is positioned deeper into the wall construction. the negative influence of shading is even more pronounced on the nzeb because of its thicker walls. it is apparent that due to the different overall wall thicknesses, the optimal reldiscussion 69 journal of sustainable architecture and civil engineering 2019/1/24 ative installation depth is different on the two versions of the building. however, the distances from the frame midpoint to the façade plane, at which the net heat demand is the lowest, is about the same on both the nzeb and leb. this is because the influence of the solar gain on the overall building energy balance is greater than the influence of window installation ltt. thus, it is preferable to install the windows towards the outside of the wall construction, but in such a way that the temperature factor frsi is within safe limits. further optimisation of the installation thermal bridge has little effect and one can omit this in the planning phase of the building, thus simplifying the process. conclusions in this paper, a series of simulation energy analyses were performed to determine the effect of window frame parameters and the window installation depth to the net heat demand of a very energy efficient building. the results show that the window frame thermal transmittance and the width of the window frame have noticeable effect on the total energy demand of the building. however, the influence of window installation depth is insignificant. nevertheless, it is suggested to install the window more to the outside of the wall construction to minimise window reveal and overhang shading. concurrently it is important to keep the temperature factor within safe limits. if that is ensured, further optimisation work is not particularly beneficial. acknowledgment bülow-hübe, h. the effect of glazing type and size on annual heating and cooling demand for swedish offices. report no. tabk--01/1022, 2001. cuce, e., & riffat, s. b. a state-of-the-art review on innovative glazing technologies. renewable and sustainable energy reviews, 2015; 41, 695–714. https://doi.org/10.1016/j.rser.2014.08.084 directive 2010/31/eu. directive 2010/31/eu of the european parliament and of the council on the energy performance of buildings (recast). en iso 13788:2012. en iso 13788:2012 hygrothermal performance of building components and building elements internal surface temperature to avoid critical surface humidity and interstitial condensation calculation methods. feist, w. passive solarenergienutzung im passivhaus; protokollband 13 energiebilanzen mit dem passivhaus projektierungs paket 1998. feist, w., sariri, v., ebel, w., & baffia, e. solareinstrahlung in abhängigkeit von der orientierung und verschattung; protokollband 14 passivhaus-fenster 1998. feist, w., schnieders, j., dorer, v., & haas, a. re-inventing air heating: convenient and comfortable within the frame of the passive house concept. referencesenergy and buildings, 2005a; 37(11), 1186–1203. https://doi.org/10.1016/j.enbuild.2005.06.020 feist, w., schnieders, j., dorer, v., & haas, a. re-inventing air heating: convenient and comfortable within the frame of the passive house concept. energy and buildings, 2005b; 37(11), 1186–1203. https://doi.org/10.1016/j.enbuild.2005.06.020 grynning, s., gustavsen, a., time, b., & jelle, b. p. windows in the buildings of tomorrow: energy losers or energy gainers? energy and buildings, 2013; 61, 185– 192. https://doi.org/10.1016/j.enbuild.2013.02.029 grynning, s., time, b., & uvsløkk, s. an overview and some reflections on energy saving potentials by heat loss reduction through the building envelope. project report to be published within the research centre on zero emission buildings 2011. harmati, n., & magyar, z. influence of wwr, wg and glazing properties on the annual heating and cooling energy demand in buildings. energy procedia, 2015; 78, 2458–2463. https://doi.org/10.1016/j.egypro.2015.11.229 ihm, p., park, l., krarti, m., & seo, d. impact of window selection on the energy performance of residential buildings in south korea. energy policy, 2012; 44, 1–9. https://doi.org/10.1016/j.enpol.2011.08.046 this research utilises measurement data from h2020 project no 754177: “nero cost reduction of new nearly zero-energy wooden buildings in the northern climatic conditions”. the research was co-financed by the estonian research council with personal research funding prg483 “moisture safety of interior insulation, constructional moisture and thermally efficient building envelope”, institutional research funding grant iut1-15, estonian centre of excellence in zero energy and resource efficient smart buildings and districts, zebe, grant tk146 funded by the european regional development fund. the authors would also like to thank sense oü for cooperation of providing data and details about the reference building. journal of sustainable architecture and civil engineering 2019/1/24 70 iso 10077-1:2017. iso 10077-1:2017 thermal performance of windows, doors and shutters -calculation of thermal transmittance -part 1: general. iso 10077-2:2017. iso 10077-2:2017 thermal performance of windows, doors and shutters -calculation of thermal transmittance -part 2: numerical method for frames. iso 10211:2017. iso 10211:2017 thermal bridges in building construction -heat flows and surface temperatures -detailed calculations. iso 13790:2008. en iso 13790:2008 energy performance of buildings calculation of energy use for space heating and cooling 2008. iso 6946:2017. iso 6946:2017 building components and building elements thermal resistance and thermal transmittance calculation methods n.d. kalamees, t. critical values for the temperature factor to assess thermal bridges. proc. estonian acad. sci. eng, 2006; 12, 3–4. kalamees, t., & kurnitski, j. estonian test reference year for energy calculations. proc. estonian acad. sci. eng, 2006; 12, 40–58. lbnl. therm 7 / window 7 nfrc simulation manual 2017. leskovar, v. ž., & premrov, m. an approach in architectural design of energy-efficient timber buildings with a focus on the optimal glazing size in the south-oriented façade. energy and buildings, 2011; 43(12), 3410–3418. https://doi.org/10.1016/j.enbuild.2011.09.003 marino, c., nucara, a., & pietrafesa, m. does windowto-wall ratio have a significant effect on the energy consumption of buildings? a parametric analysis in italian climate conditions. journal of building engineering, 2017; 13, 169–183. https://doi.org/10.1016/j.jobe.2017.08.001 misiopecki, c., bouquin, m., gustavsen, a., & jelle, b. p. thermal modeling and investigation of the most energy-efficient window position. energy and buildings, 2018; 158, 1079–1086. https://doi.org/10.1016/j.enbuild.2017.10.021 passive house institute. passive house planning package version 8 2013. darmstadt. persson, m.-l., roos, a., & wall, m. influence of window size on the energy balance of low energy houses. energy and buildings, 2006; 38(3), 181–188. https://doi. org/10.1016/j.enbuild.2005.05.006 rt i 05.06.2015; 15. hoone energiatõhususe miinimumnõuded (minimum requirements for energy performance of buildings). rt i 19.01.2018; 7. hoone energiatõhususe arvutamise metoodika (methodology for calculating the energy performance of buildings). sadineni, s. b., madala, s., & boehm, r. f. passive building energy savings: a review of building envelope components. renewable and sustainable energy reviews, 2011; 15(8), 3617–3631. https://doi.org/10.1016/j.rser.2011.07.014 schnieders, j., & hermelink, a. cepheus results: measurements and occupants’ satisfaction provide evidence for passive houses being an option for sustainable building. energy policy, 2006; 34(2), 151–171. https://doi. org/10.1016/j.enpol.2004.08.049 susorova, i., tabibzadeh, m., rahman, a., clack, h. l., & elnimeiri, m. the effect of geometry factors on fenestration energy performance and energy savings in office buildings. energy and buildings, 2013; 57, 6–13. https:// doi.org/10.1016/j.enbuild.2012.10.035 winkler, m., antretter, f., & radon, j. critical discussion of a shading calculation method for low energy building and passive house design. energy procedia, 2017; 132, 33–38. https://doi.org/10.1016/j.egypro.2017.09.627 kristo kalbe phd candidate tallinn university of technology, department of civil engineering and architecture, nearly zero energy buildings research group main research area energy performance of prefabricated nzebs address ehitajate tee 5, tallinn 19086, estonia tel. +372 53456148 e-mail: kristo.kalbe@taltech.ee targo kalamees professor tallinn university of technology, department of civil engineering and architecture, nearly zero energy buildings research group main research area building envelope structures; renovation of buildings; hygrothermal behaviour of buildings structures (computer simulations, laboratory experiments, field studies); moisture safety of buildings; boundary conditions for hygrothermal simulations and experiments; building energy consumption and healthy building design; indoor climate and indoor air quality of residential-, office-, and historic buildings address ehitajate tee 5, tallinn 19086, estonia tel. +3726202403 e-mail: targo.kalamees@taltech.ee about the authors 33 recycled aggregate concrete with fluorescent waste glass and coal/ wood ash concrete wastes patricija kara1*, aleksandrs korjakins1 1riga technical university, institute of materials and structures, professor group of building materials and products, 1 kalku str., riga, lv-1658, latvia * corresponding author: patricija.kara@rtu.lv consumption of natural aggregate as the largest concrete component is constantly and rapidly increasing with the increase in the production and utilization of concrete. recycled aggregate is a valuable resource as replacement for virgin aggregate in concrete. in present study is investigated the approach of optimized utilization of concrete aggregate wastes (caw) in concrete. the produced concrete cube specimens with fluorescent waste glass powder/suspension and fly/wood ash after determination of their mechanical properties are recycled and used as partial replacement of natural aggregates in recycled aggregate concrete (rac). therefore, it helps to convert waste product with determined properties into recourse and potentially to reduce the amount of waste disposed and preserve natural resources. the mechanical properties of recycled aggregate concrete are discussed from the point of the potential of its utilization in structural concrete. keywords: fluorescent waste glass suspension, coal/wood ash, recycled concrete aggregate waste. darnioji architektūra ir statyba 2012. no. 1(1) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction concrete as a primary building construction material is the most consumed man-made material in the world. in 2007 the world concrete consumption was 11 billion tons or approximately 11.7 ton for each living human being (mehta 2006, naik 2005, naik 2008). one of the most important parts of concrete is cement as hydraulic binder and production of cement itself is an energy-intensive and highly polluting process which contributes about 5-8% to global co2 emissions and accounts for 3% of total (5% of industrial) energy consumption worldwide. production of each ton of cement results one ton of carbon dioxide (co2) (gartner 2004) into the atmosphere. the aggregates constitute approximately 80% of concrete volume. according to mehta (2006), the global concrete industry consumes about 10 billion tons of sand and rocks and taking into account today’s industry development this number is even higher. concrete being as a primary material in construction industry also is one of the most consuming landfills waste materials. the disposal of the construction and demolition (c&d) waste is becoming increasingly difficult and expensive and also environmental concerns are increasingly limiting the option of landfilling such waste. the scarcity of virgin aggregates and the increasing cost of landfilling the c&d waste are encouraging more valueadded use of recycled aggregate (demolished concrete). production and transport of virgin aggregates generate emissions representing 0.0046 million tons of carbon equivalent for each ton of virgin aggregate, compared to only 0.0024 million tons of carbon equivalent per ton of recycled aggregates (e.p.a. 2003). planners, engineers and public authorities are looking for ways of making reuse of c&d waste and, therefore, there is important concern to find optimal approach of production of concrete with preferably reduced cement volume and equal/improved properties in comparison to conventional concrete, concrete waste utilization and its recycling. in 2002 the total volume of c&d waste was over 1 billion tons annually (mehta, 2002). according to data in 2008, about 300 million tons of c&d waste were generated in the u.s. each year and about 50% of this waste was recovered for recycling and the rest was landfilled (damtoft 2008). recycled aggregate is a valuable resource; valueadded consumption of recycled aggregate, as replacement for virgin aggregate in concrete, can yield significant energy and environmental benefits. concrete produced with coarse recycled aggregate and natural sand differs from normal concrete produced with virgin aggregates in terms of some mechanical properties and durability characteristics. some of these differences depend upon the quality of the original concrete from which the recycled aggregate is obtained for use in recycled aggregate concrete (tavakoli 1996, hansen 1983, shayan 2003). original concrete of relatively low strength tends to produce lower-quality aggregates when compared with higher-strength original concrete as far as the effects on the strength and durability of recycled aggregate concrete are concerned. it has been reported that recycled aggregate concrete with properties http://dx.doi.org/10.5755/j01.sace.1.1.2615 34 in fresh and hardened states that are comparable to those of normal concrete can be produced using coarse recycled aggregate of desired quality and natural sand (shayan 2003, hansen 1992). the use of recycled aggregate in concrete is hindered by its higher water absorption (two to three times that of normal aggregate) and the increased shrinkage of the resulting recycled aggregate concrete. these drawbacks result largely from the cement hydrates (from old concrete) that adhere to the surface of recycled aggregates. it should be noted that most aggregates offer engineering properties that are superior to these of cement hydrates (nassar and soroushian 2012). recycled aggregates constitute only 5% of the total aggregate used in concrete (mehta 2006, naik 2005, naik, 2008). several researchers (salem et al. 2003, buyle-bodin and hadjieva-zaharieva 2002, ravindrarajah 1985) have found increased water absorption, drying shrinkage and particularly air permeability of the recycled aggregate concrete when compared with normal. an initial absorption that is nearly four times that of normal concrete has been measured with recycled aggregate concrete (buyle-bodin and hadjievazaharieva 2002). increased moisture absorption and drying shrinkage of recycled aggregate concrete adversely influence its long-term performance and durability (mehta 2006, neville 2000, basheer et al. 2001). moisture movement in hydrated cement paste influences the drying shrinkage of concrete. large-volume use of recycled aggregate concrete requires resolution of the problems with increased water absorption drying shrinkage resulting concrete. glass is also one of the most popular materials due to progressive growth of urbanization nowadays, but increased production of glass causes also simultaneously the growth of glass wastes. disposal of this waste is a complex problem for many countries in the world. according to data of 2009 in latvia have been imported 42.6 thousand tonnes of glass and the recycling of glass waste was 12.5 thousand tonnes (kara et al. 2012). recycling of post-consumer glass for use as raw material in production of new glass is very limited, mainly due to the mixed-color nature of waste glass. in the sixties, many studies have been devoted to use crushed glass waste as an aggregate for concrete production (pike et al. 1960, schmidt and saia 1963, jonhston 1974). this aggregate was also applied in road construction. the glass waste was also used for production of glass tiles and bricks, wall panels, glass fibre, agriculture fertiliser, landscaping reflective beads and tableware (reindl 1998). the properties of glass seemed comparable to those of large aggregate in terms of constitution, strength and durability, and the larger size of the glass meant lower processing costs. these early attempts however, were unsuccessful due to the alkali– silica reaction (asr) which takes place in the presence of the amorphous waste glass and concrete pore solution with marked strength reduction and simultaneous excessive expansion (shao 2000). due to high disposal costs of glass wastes, the use of glass as concrete aggregate again attracted the attention of researchers and it was found that if glass was ground to a particle size of 300μm or smaller, the asr induced expansion could be reduced and in fact, data reported in the literature that if waste glass finely ground under 75μm, this effect does not occur and mortar durability is guaranteed (shao 2000). the benefits of developing alternative or supplementary cementing materials as partial substitution for ordinary portland cement (opc) powder were described by malhotra and mehta (1996). non-recycled waste glass due to specific chemical composition (with heavy and toxic metals) constitutes a problem for solid waste disposal and therefore it has even more limited market in comparison to mixed-color nature of waste glass (cullet). non-recycled waste glass like fluorescent lamp glass causes a problem for disposal because it is not biodegradable and landfill is not the best environment friendly solution for it. for example, yearly from 300 to 500 tonnes of fluorescent lamps are partially recycled in latvia (kara 2012). the used borosilicate (drl) and leaden silicate (lb) waste glass powders obtained from fluorescent lamp chippings after recycling process which includes lamp classification, glass separation, cleaning from harmful components, crushing into chippings and grinding can be applicable as microfiller in concrete (shakhmenko 2009, kara 2012). waste glass as powder milled to certain surface specific area in order to accelerate beneficial chemical reactions in concrete offers desired chemical composition and reactivity for use it as a supplementary cementitious material (scm) for enhancing the chemical stability, pore system characteristics, moisture resistance and durability of concrete. the beneficial effects of milled waste glass can enhance the residual cement occurring on the surface of recycled aggregates, thus improving the performance characteristics of recycled aggregate concrete (nassar and soroushian 2012). the old mortar / paste clinging to the surface of recycled aggregate are porous in nature due to the presence of large oriented crystals of calcium hydroxide (a product of cement hydration) at the aggregate-remnant interface. when milled waste glass is used in recycled aggregate concrete as partial replacement of cement, it interacts with calcium hydroxide to form calcium silicate hydrate (c-s-h) which is the key binder among cement hydrates. this reaction can enhance the quality of the remnant cement paste on recycled aggregates, thus benefiting the impermeability and dimensional stability of recycled aggregate concrete (nassar and soroushian 2012). in present study is investigated the approach of optimized utilization of concrete aggregate wastes (caw) in concrete. the produced concrete cube specimens with fluorescent waste glass and fly/wood ash after determination of their mechanical properties are recycled and used as partial replacement of natural aggregates in recycled aggregate concrete (rac). therefore, it helps to convert waste product with determined properties into recourse and potentially to reduce the amount of waste disposed and preserve natural resources. 2. methods an experimental study was carried out to investigate the effects on the mechanical properties of concrete with caw obtained from crushed concrete specimens (from previous studies with cement substitution at level of 30% with waste borosilicate (drl) glass chippings obtained from fluorescent lamps and ground into powder with 35 specific surface area of 2310 cm2/g and coal/wood ashes (kara, 2012)) after they have been stored as concrete waste. crushed concrete specimens grains from coal/wood ash concrete, drl – fluorescent waste glass concrete, drls – fluorescent waste glass suspension concrete were separated into fractions (4/8mm, 8/11.2mm, 11.2/16mm) (see fig. 1). ordinary portland cement cem i 42.5n from “kunda nordic” (estonia) was applied as binding agent. cement conforms to standard evs en 197-1:2002 “cement – part 1: composition, specifications and conformity criteria for common cements”. natural local aggregates (gravel, crushed stone and sand) have been used for mix preparation. coal ash wood ash drl drls fig. 1. concrete aggregate wastes sikament 56 polycarboxylat plasticizing agent was added in several concrete mixes. a total of 15 different concrete mixes were prepared. three sets of experiments were hold. the first set of experiments included 7 mixes and was made with natural aggregate substitution by 100%: control mix with gravel 4-11.2mm (named ctrl), control mix with crashed stones 4-11.2mm (named ctrl1), 2 mixes with coal rac 4-11.2mm but different w/c ratios – rc (w/c=0.49) and rc1(w/c=0.59) 4-11.2mm, 1 mix with wood rac (named rw) 4-11.2mm, 1 mix with drl fluorescent waste glass rac 4-11.2mm (named rdrl) and 1 mix with drl fluorescent waste glass suspension rac 4-11.2mm (named rdrls). the second set of experiments included 4 mixes and was made with natural aggregate substitution by 50%: control mix with gravel 4-11.2mm (50%) and crashed stones 4-11.2mm (50%) (named ctrl2), 1 mix with coal rac (50%) 4-11.2mm and with gravel 4-11.2mm (50%) and crashed stones 4-11.2mm (50%) (named rc2), 1 mix with wood rac (50%) 4-11.2mm and with gravel 4-11.2mm (50%) and crashed stones 4-11.2mm (50%) (named rw2), 1 mix with drl fluorescent waste glass suspension rac (50%) 4-11.2mm and with gravel 4-11.2mm (50%) and crashed stones 4-11.2mm (50%) (named rdrls2). the third set of experiments included 4 mixes and was made with natural aggregate substitution by 50% and plasticizer: control mix with gravel 4-11.2mm (50%) and crashed stones 4-11.2mm (50%) (named ctrl3), 1 mix with coal rac (50%) 4-11.2mm and with gravel 4-11.2mm (50%) and crashed stones 4-11.2mm (50%) (named rc3), 1 mix with wood rac (50%) 4-11.2mm and with gravel 4-11.2mm (50%) and crashed stones 4-11.2mm (50%) (named rw3), 1 mix with drl fluorescent waste glass rac (50%) 4-11.2mm and with gravel 4-11.2mm (50%) and crashed stones 4-11.2mm (50%) (named rdrl3). table 1. concrete mix compositions, kg/m3 mix type w/c ratio portland cement cem i 42,5 n gravel (4,0-11,2 mm) crashed stone (4,0-11,2 mm) natural sand (0,3-2,5 mm) quartz sand (0-1,0 mm) caw plasticizer water ctrl 0.49 410 1000 650 119 200 ctrl1 0.49 410 1000 650 119 200 rc 0.49 410 650 119 1000 200 rc1 0.59 410 650 119 1000 242 rw 0.49 410 650 119 1000 200 rdrl 0.49 410 650 119 1000 200 rdrls 0.49 410 650 119 1000 200 ctrl2 0.59 410 500 500 650 119 242 rc2 0.59 410 500 650 119 500 242 rw2 0.59 410 500 650 119 500 242 rdrls2 0.59 410 500 650 119 500 242 ctrl3 0.49 410 845 155 650 119 7 200 rc3 0.49 410 423 77 650 119 500 7 200 rw3 0.49 410 423 77 650 119 500 7 200 rdrl3 0.49 410 423 77 650 119 500 7 200 36 details for different mixes are shown in table 1. all concrete mixes were made with capacity of 6.2 litres. the mixing procedure was following: ▪ mixing of the dry ingredients for 120 s; ▪ adding 70% of the total water for 60 s; ▪ adding the rest of the water and mixing for 60 s. as soon as the mixing finished, abram slump test was carried out for each mix in accordance with lvs en 12350-2:2009 “testing fresh concrete – part 2: slump test”. specimens were cast in 100x100x100 mm plastic or steel moulds, which conform to standard lvs en 12390-1:2009 “testing hardened concrete – part 1: shape, dimensions and other requirements for specimens and moulds”. the moulds were cleaned and lightly coated with form oil before the casting procedure. concrete was compacted on a vibrating table. after that the specimens were covered with polyethylene pellicle and left to set for 24 hours (w/t plasticizing agent) and for 48 hours (with plasticizing agent). then they were removed from moulds and cured in water (with temperature +20±2°c) for 7 days and in curing chamber (with air temperature +20±2°c and relative humidity ≥95%, see figure 1) for other 21 days or until testing, thus conforming to lvs en 12390-2:2009 “testing hardened concrete – part 2: making and curing specimens for strength tests”. to evaluate hardened concrete properties compressive strength test was carried out. before the test, the specimens were dried. the testing was done according to lvs en 12390-3:2009 “testing hardened concrete – part 3: compressive strength of test specimens”. compression testing machine with the accuracy of ±1% was used; the rate of loading was 0.7 mpa/s. compressive strength was conducted up to 112 days. three specimens per mix for each age were prepared and the mean compressive strength value was calculated. the concrete strength containing ground waste glass was compared to the concrete control mix. 3. results and discussion the results for fresh concrete properties – slump test – are summarized in table 2. the slump class for almost all mixes varied between s1 and s2, except for the control mix with plasticizer (ctrl3) and mix with drl fluorescent waste glass suspension caw (rdrls2). coal/wood caw showed better workability on concrete in comparison to fluorescent waste glass caw. that could be described by different water absorption levels of caw in mixes. however, as it is evident from the experiment, additional water amount improved workability of rdrls2 and also decreased the compressive strength value. concrete cubes’ strength tests were carried out after 7, 28, 56, 84 and 112 days. after 7 days of hardening, the first part of samples was tested on compression strength. the specimens were dried before the test. three tests per mix for each age were carried out – to measure the compressive strength. the testing was done according to lvs en table 2. slump test results ctrl ctrl 1 rc rc1 rw rdrl rdrls ctrl2 rc2 rw2 rdrls2 ctrl3 rc3 rw3 rdrl3 slump, mm 30 10 30 40 30 20 20 45 45 50 95 160 20 55 40 slump, class s1 s1 s1 s1 s1 s1 s1 s2 s2 s2 s2/s3 s4 s1 s2 s1 p. kara, a. korjakins 42 the slump class for almost all mixes varied between s1 and s2, except for the control mix with plasticizer (ctrl3) and mix with drl fluorescent waste glass suspension caw (rdrls2). coal/wood caw showed better workability on concrete in comparison to fluorescent waste glass caw. that could be described by different water absorption levels of caw in mixes. however, as it is evident from the experiment, additional water amount improved workability of rdrls2 and also decreased the compressive strength value. concrete cubes’ strength tests were carried out after 7, 28, 56, 84 and 112 days. after 7 days of hardening, the first part of samples was tested on compression strength. the specimens were dried before the test. three tests per mix for each age were carried out – to measure the compressive strength. the testing was done according to lvs en 12390-3:2009 “testing hardened concrete – part 3: compressive strength of test specimens”. compression testing machine with the accuracy of ±1% was used; the rate of loading was 0.7 mpa/s. fig. 2 shows the results from the first set of experiments when natural aggregates were substituted by caw at level of 100%. two kinds of natural aggregates were available during the experiments: gravel and crushed stones. as to the results of the compressive strength of ctrl and ctrl1, they don’t differ so much, however compressive strength of crashed stones was higher than gravel and this natural aggregates were considered more for experiments. at the age of 7 days mixes with wood caw and rdrls showed higher results than mix with drl fluorescent waste glass powder and coal caw. at the age of 28 days the results of caw concrete were lower in comparison to control mixes, only rdrls had higher result for 7-11% in comparison to control mixes. at the age of 56 days all mixes had equal or higher results on compressive strength in comparison to control mixes. the best results were for rw = 66.4mpa and rdrls=66.0mpa, but at the age of 112 day mix rdrls gained higher strength for 8% than mix rw with value of 74mpa. fig. 2. influence of caw (100%) content and curing time on the concrete compressive strength fig. 3 shows the results from the second set of experiments when natural aggregates were substituted by caw at level of 50%. the water amount was increased for this set of experiments in order to improve concrete workability. the compressive strength results were lower for all mixes with caw in comparison to control mixes and only rdrls2 mix at the age of 56 days showed equal result to ctrl2, 60.4mpa, not big difference was observed at later ages of curing specimens. fig. 2. influence of caw (100%) content and curing time on the concrete compressive strength 37 12390-3:2009 “testing hardened concrete – part 3: compressive strength of test specimens”. compression testing machine with the accuracy of ±1% was used; the rate of loading was 0.7 mpa/s. fig. 2 shows the results from the first set of experiments when natural aggregates were substituted by caw at level of 100%. two kinds of natural aggregates were available during the experiments: gravel and crushed stones. as to the results of the compressive strength of ctrl and ctrl1, they don’t differ so much, however compressive strength of crashed stones was higher than gravel and this natural aggregates were considered more for experiments. at the age of 7 days mixes with wood caw and rdrls showed higher results than mix with drl fluorescent waste glass powder and coal caw. at the age of 28 days the results of caw concrete were lower in comparison to control mixes, only rdrls had higher result for 7-11% in comparison to control mixes. at the age of 56 days all mixes had equal or higher results on compressive strength in comparison to control mixes. the best results were for rw = 66.4mpa and rdrls=66.0mpa, but at the age of 112 day mix rdrls gained higher strength for 8% than mix rw with value of 74mpa. fig. 3 shows the results from the second set of experiments when natural aggregates were substituted by caw at level of 50%. the water amount was increased for this set of experiments in order to improve concrete workability. the compressive strength results were lower for all mixes with caw in comparison to control mixes and only rdrls2 mix at the age of 56 days showed equal result to ctrl2, 60.4mpa, not big difference was observed at later ages of curing specimens. in the third experiment set (fig. 4) plasticizer was added into mix keeping the same water amount as in the first set of experiments. plasticizer influenced on workability of control mix and not so much on the caw mixes. coal caw mix had worse workability, rw3 and rdrl3 better as in second experiment set. the compressive strength results of recycled aggregate concrete with fluorescent waste glass and coal/wood ash concrete wastes 43 fig. 3. influence of caw (50%) content and curing time on the concrete compressive strength fig. 4. influence of caw (50%) and plasticizer content and curing time on the concrete compressive strength in the third experiment set (fig. 4) plasticizer was added into mix keeping the same water amount as in the first set of experiments. plasticizer influenced on workability of control mix and not so much on the caw mixes. coal caw mix had worse workability, rw3 and rdrl3 better as in second experiment set. the compressive strength results of rc3 were equal to control mix within the 7 and 28 days, and were higher at the age of 56-112 days. the best result for this group was mix rdrl3 with the value of 76.5 mpa. it is possible to see from present research that recycled concrete aggregate is a valuable resource as replacement for virgin aggregate in concrete carrying some environmental benefits. increasing recycled concrete aggregate content leads to increased water absorption, however it depends on the caw used. as it was observed from the first set of experiments the slump’s value of coal/wood caw mix was equal to control mix, also with modified w/c ratio caw mix’s slump was equal to control mix, and only mixes with fluorescent waste glass suspension were performing better workability except the third set of experiments with plasticizer. that could be described by the morphology of caw grains and also chemical composition of old mortar remained from previous studies (kara 2012). the optimal natural aggregate substitution level with caw in concrete could be around 100% with optimized w/c ratio and needed workability taking into account that compressive strength for concrete structural elements is important at the age of 7 days and 28 days. in comparison to control mix only rw and rdrls mixes could competitive results but taking into account that structural elements compressive strength is in the range up to 50 mpa, the results obtained from this study are satisfied for all mixes. fig. 3. influence of caw (50%) content and curing time on the concrete compressive strength recycled aggregate concrete with fluorescent waste glass and coal/wood ash concrete wastes 43 fig. 3. influence of caw (50%) content and curing time on the concrete compressive strength fig. 4. influence of caw (50%) and plasticizer content and curing time on the concrete compressive strength in the third experiment set (fig. 4) plasticizer was added into mix keeping the same water amount as in the first set of experiments. plasticizer influenced on workability of control mix and not so much on the caw mixes. coal caw mix had worse workability, rw3 and rdrl3 better as in second experiment set. the compressive strength results of rc3 were equal to control mix within the 7 and 28 days, and were higher at the age of 56-112 days. the best result for this group was mix rdrl3 with the value of 76.5 mpa. it is possible to see from present research that recycled concrete aggregate is a valuable resource as replacement for virgin aggregate in concrete carrying some environmental benefits. increasing recycled concrete aggregate content leads to increased water absorption, however it depends on the caw used. as it was observed from the first set of experiments the slump’s value of coal/wood caw mix was equal to control mix, also with modified w/c ratio caw mix’s slump was equal to control mix, and only mixes with fluorescent waste glass suspension were performing better workability except the third set of experiments with plasticizer. that could be described by the morphology of caw grains and also chemical composition of old mortar remained from previous studies (kara 2012). the optimal natural aggregate substitution level with caw in concrete could be around 100% with optimized w/c ratio and needed workability taking into account that compressive strength for concrete structural elements is important at the age of 7 days and 28 days. in comparison to control mix only rw and rdrls mixes could competitive results but taking into account that structural elements compressive strength is in the range up to 50 mpa, the results obtained from this study are satisfied for all mixes. fig. 4. influence of caw (50%) and plasticizer content and curing time on the concrete compressive strength 38 rc3 were equal to control mix within the 7 and 28 days, and were higher at the age of 56-112 days. the best result for this group was mix rdrl3 with the value of 76.5 mpa. it is possible to see from present research that recycled concrete aggregate is a valuable resource as replacement for virgin aggregate in concrete carrying some environmental benefits. increasing recycled concrete aggregate content leads to increased water absorption, however it depends on the caw used. as it was observed from the first set of experiments the slump’s value of coal/wood caw mix was equal to control mix, also with modified w/c ratio caw mix’s slump was equal to control mix, and only mixes with fluorescent waste glass suspension were performing better workability except the third set of experiments with plasticizer. that could be described by the morphology of caw grains and also chemical composition of old mortar remained from previous studies (kara 2012). the optimal natural aggregate substitution level with caw in concrete could be around 100% with optimized w/c ratio and needed workability taking into account that compressive strength for concrete structural elements is important at the age of 7 days and 28 days. in comparison to control mix only rw and rdrls mixes could competitive results but taking into account that structural elements compressive strength is in the range up to 50 mpa, the results obtained from this study are satisfied for all mixes. waste glass as powder ground to certain surface specific area in order to accelerate beneficial chemical reactions in concrete offers desired chemical composition and reactivity for use it as a supplementary cementitious material (scm) for enhancing the chemical stability, pore system characteristics, moisture resistance and durability of concrete. as it was observed from present study, the waste glass mixes acted different from coal/wood ash mixes, but more detailed investigation must be carried out in this field. the next step could be the use of waste glass as cement partial replacement at level of 20-30% in mixes with caw, which could improve the performance characteristics of recycled aggregate concrete and also set of x-ray experiments in order to observe how calcium silicate hydrates are forming. 4. conclusions the effect of caw on compressive strength appears to be dependent on original concrete quality and mix proportions, water/cement ratio and workability. recycled aggregates from demolished concrete are generally produced by crushing, screening and removing the contaminants by water cleaning, air-shifting and magnetic separation. the quality of such aggregate usually is lower due to remained amount of mortar on original aggregate grains. the utilization of recycled aggregates in structural concrete should help to improve the environmental performance of concrete. according up-to-date state of research in the area of recycled aggregates utilization from demolished concrete in structural concrete is technically feasible but limited since it is not recommended to apply this kind of concrete for structural elements which are expected to have high stresses and deformations in service because the long-term behavior is not well-known yet and also it is not recommended due to its uncertain durability performance. in present study recycled aggregates from concrete specimens with known mix composition have performed good mechanical strength results. the best obtained result was for the mixes with waste fluorescent glass caw. substitution of natural aggregates can be one of possibilities to take care of landfills and increase of co2 emissions into the atmosphere in latvia. there are not developed regulatory standards for recycled concrete use in construction in latvia. it would be important to develop and implement the rules of the use of recycled concrete aggregates in structural concrete in latvia after detailed research in this field will be carried out. acknowledgements the financial support of the eraf project nr. 2010/0286/2dp/2.1.1.1.0/10/apia/viaa/033 „high efficiency nanoconcretes” is acknowledged. references buyle-bodin, f., hadjieva-zaharieva r. 2002. influence of industrially produced recycled aggregates on flow properties of concrete. materials and structures. 35. 504-509. damtoft, j. s., 2008. sustainable development and climate change initiatives. cement and concrete research, 38(2). 115-127. epa-530-f06-039. 2006. environmental protection agency, municipal solid waste generation, recycling and disposal in the united states:facts and figures for 2005. epa 530-r-03-017. 2003. background document for life-cycle greenhouse emission factors for clay brick reuse and concrete recycling. gartner, e. 2004. industrially interesting approaches to low co2 cements. cement and concrete research. 34. 1489-1498. hansen, t. c. 1992.recycling of demolished concrete and masonry. taylor & francis. 336. hansen, t. c., narad, h. 1983. strength of recycled concrete made from crushed concrete coarse aggregate. concrete international. 5. 79-83. jonhston, c. d. 1974. waste glass as coarse aggregate for concrete. j test eval. 2(5). 344-350 kara, p., korjakins, a. 2012. concrete with fluorescent waste glass suspension. in: proceedings of 8th international conference: concrete in the low carbon era 2012, dundee, uk. (in press) kara, p., korjakins, a., kovalenko, k. 2012. the usage of fluorescent waste glass powder in concrete. scientific journal of riga technical university, construction science, 13 vol., 26-32. kara, p., korjakins, a., stokmanis-blaus, v. 2012. evaluation of properties of concrete incorporating ash as mineral admixtures. scientific journal of riga technical university, construction science, 13 vol., 17-25. malhotra, v. m, mehta, p. k. 1996. pozzolanic and cementitious materials. in: advances in concrete technology. new york: gordon and breach publishers. mehta, p. k. 2008. greening of concrete industry for sustainable development. concrete international. 23-28. 39 naik, t. r. 2005. sustainability of cement and concrete industries. in: proceedings of the international conference on achieving sustainability in construction, 2005, 141-150. naik, t. r. 2008. sustainability of concrete construction. practice periodical on structural design and construction. 13(2). 98-103. neville, a. m. 2000. properties of concrete. 4th ed. pearson education. pike, r. g, hubbard, newman, d, binary, e.s. 1960. silicate glasses in the study of alkali aggregate reaction. high res. board bull. 275. 39-44 ravindrarajah, sri, r. 1985. properties of concrete made with crushed concrete as coarse aggregate. magazine of concrete research. 37(130). reindl, j. 1998. report by recycling manager, dane county, department of public works, madison, usa. nassar, roz-ud-din, soroushian, p. 2012. srength and durability of recycled aggregate concrete containing milled glass aspartial replacement for cement. construction and building materials. 29. 368-377. salem, r. m., burdette e. g., jackson, n. m. 2003. resistance to freezing and thawing of recycled aggregate concrete. aci materials journal. 100. 216-221. shakhmenko, g., korjakins, a., bumanis, g. 2009. bore-silicate glass waste of lamp as a micro-filler for concrete. scientific journal of rtu construction science. vol. 10, 131-138. shao, y., lefort, t., moras, s., rodriguez, d. 2000. studies on concrete containing ground waste glass. cement and concrete research. 30. 91-100. shayan, a., xu, a. 2003. performance and properties of structural concrete made with recycled concrete aggregate. aci materials journal. 100. 371-380. schmidt, a, saia, whf. 1963. alkali-aggregate reaction tests on glass used for exposed aggregate wall panel work. aci mater j. 60.1235-1236 tavakoli, m., mid, p., soroushian, p. 1996. strengths of recycled aggregate concrete made using field-demolished concrete as aggregate. aci materials journal. 93. 182-190. received 2012 06 19 accepted after revision 2012 09 03 patricija kara – scientific researcher, lecturer at riga technical university, institute of materials and structures, professor group of building materials and products. main research area: reuse of industrial wastes and by-products, concrete micro structural behaviour, concrete fracture, concrete technology, ecological building materials. address: 16 azenes st., riga lv-1048, latvia. tel.: +371 670 89243 e-mail: patricija.kara@rtu.lv aleksandrs korjakins – professor at riga technical university, institute of materials and structures. chair of professor group of building materials and products. main research area: building materials and structures, ecological building materials, reuse of industrial waste. address: 16 azenes st., riga lv-1048, latvia. tel.: +371 670 89248 e-mail: aleksandrs.korjakins@rtu.lv 46 recycling possibilities of sewage sludge from water purification ineta rozenstrauha1*, sergejs survila1, linda krage1, modris drille1, gaida sedmale1 and inese pastare2 1riga technical university, faculty of materials science and applied chemistry, azenes str. 14/24, lv-1048, riga, latvia 2 riga water ltd, z.a.meierovica blwd.1, riga, lv-1050, riga, latvia * corresponding author: ineta@ktf.rtu.lv the sewage sludge from a water purification plant was analysed for recycling to the dense glass-ceramic materials. the sewage sludge containing aluminium compounds and circa 50 % of organic matter was used as a filler, but as the matrix of glass-ceramic was examined an illitic clay from liepa deposit (latvia). the raw materials were investigated by differential-thermal (dta) and x-ray diffraction analysis (xrd). the dense glass-ceramic was produced from the water purification sewage sludge and limeless clay in ratio 10-40 : 90-60. the optimal values of bulk density (2.28 g/cm3) and thermal shrinkage (29 %) for novel materials were observed for glass-ceramic with the sludge additive at amount of 20 wt %, obtained by sintering at temperature 1140 °c. the relationship between thermal treatment conditions and maximal treatment temperature was established. the following crystalline phases for novel materials were detected by xrd analysis: microcline (kalsi3o8), hematite (fe2o3), quartz (sio2) and corundum (al2o3). the physical-chemical properties of novel materials correspond to the dense glass-ceramics composite while the material itself could be applied as building material. keywords: recycling, sewage sludge, glass-ceramics. darnioji architektūra ir statyba 2012. no. 1(1) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction annually increasing amount of dry sewage sludge from water purification gradually increases their storage problem. partly sewage sludge is used as fertilizer in the agriculture or forestry, while still unusable is the part of it containing the harmful admixtures or heavy metals. activated sludge from water purification equipment is assemblage of microorganisms (aerobous and anaerobous) having the ability to absorb the organic pollution and decompose it at the presence of air oxygen or without it. this ability is used for purification of waste or drinking water. activated sludge contains the biologic organisms – bacteria’s, protozoans and other microorganisms where the bacteria’s create the main content in the activated sludge. in most cases the chemical composition of activated sludge can be described by chemical formula c5h7o2n (ledins 2007). as one of the most cheapest and safe methods of elimination of pathogenics in the purification sludge is their composting. the compost produced is used as fertilizer in agriculture and forestry if the pollution of dry matter with hazardous elements does not exceed the threshold limit value (shinogi et al. 2003, lu et al. 2008). as one of the possibilities for recycling of sludge containing large amount of heavy metals or other hazardous elements is their addition to concrete, for example, mix from halfand-half of portland cement and sludge kept either in the autoclave or under pressure. the end-product could be used as building material (cheilas 2007). other possibility for recycling of sewage sludge is to apply it as the filler for clay bricks, described in literature (chih-huang et al. 2003), whereas the limited amount of sludge in bricks is until 20%, thus reaching the requirements of brick’s mechanical and physico-chemical properties. another possibility for recycling of industrial waste, i. e. sewage sludge, is the production of glass-ceramic materials using powder technology and sintering by thermal treatment. only specific glass compositions are suitable precursors for glass-ceramics. some glasses are too stable and difficult to crystallize, such as ordinary window glass, whereas others crystallize too readily in an uncontrollable manner resulting in undesirable microstructures. secondly, heat treatment is a critical factor in attaining acceptable and reproducible products (rawlings et al. 2006, suzuki and tanaka 1999). as the main methods for recycling of sewage sludge the powder technology and one-stage thermal treatment for production of glass-ceramic is selected. the raw materials used for the given studies were sewage sludge from drinking water preparation plant and limeless clay from deposit liepa (latvia). the limeless clay is suitable for press powder-mix while it can form the liquid phase during sintering process which is necessary for creation of glassy matrix to incorporate the part of sewage sludge (sedmalis et al. 2002, sedmale 2010, rawlings et al. 2006, svinka et al. 2011). the advantages of this method – it is simple, http://dx.doi.org/10.5755/j01.sace.1.1.2617 47 economically profitable, necessary equipment is available in already running technologies and obtained products usually are characterized with high mechanical strength. 2. methods the information about used raw material – clay is based on literature data (svinka and lindina 1994, svinka et al. 2011, sedmalis et al. 2002), while the information concerning the used sewage sludge is based on producer’s data. the mineralogical composition was determined by xrd analysis, while the determination of moisture, organic matter and ash content – performed according to the latvian standard (lvs en report 13039:2012). the raw materials were dried for 24 h by 100 ° c temperature and the mixtures were created from 60 to 90 wt % of clay and 40 until 10 wt % of sewage sludge. the compositions were milled in mechanic mill retsch rm100 for 1 hour in order to get the powder fraction with particle’s ∅ ≤ 0.5 mm. discoid samples (∅ = 10 mm) were prepared using weber pw-10 hydraulic press by pressure 6 kn (19.1 mpa) and treated thermally in nabertherm electric furnace (max temperature – 1300 ° c) with following high-temperature treatment rate: increasing rate 3 °c/min until maximal temperature interval 1100 1180 ° c and keeping time by maximal temperature 1 h. the bulk density, water uptake and porosity were measured using standard method (lvs en standard 10545-3:2002). the samples of sewage sludge and sintered glass-ceramic materials made from the already mentioned latvian industrial wastes and clay were analysed by xrd analysis. powdered glass-ceramic materials were used for xrd patterns, recorded on a rigaku ultima+ x-ray diffractometer with 50ma and 40 kv, cu k α radiation. the mineralogical identifications were made using an xrd pattern database (international centre for diffraction data, icdd). 3. results and discussion investigation of raw materials the sewage sludge contains biogenous elements needed for bacteria’s in the activated sludge – nitrogen, phosphorous, oxygen, carbon and hydrogen, as well as some trace of aluminium (al), while as the coagulant in the water purification process the aluminium sulphate (al2(so4)3x18h2o) was used (data from producer). during the entering into the water the hydrolysis of aluminium takes place which resulted with aluminium hydroxide and its polymers. the calculated content of moisture is 84.11 wt %, part of organic matter corresponds to the 55.60 wt %, while the ash content of sewage sludge is 44.03 wt %. table 1. chemical composition of applied clay oxides content, wt % al2o3 16.75 sio2 63.18 cao 0.82 tio2 0.81 mgo 2.07 fe2o3 7.64 na2o 0.14 k2o 3.46 organic substances 0.24 loi (1000 °c) 4.89 by the xrd analysis for sewage sludge treated at temperature 700 ° c as main crystalline phase the quartz (sio2) was detected (see in fig. 1). the clay used as a matrix for glass-ceramic shows the high amount of silica (sio2), alumina (al2o3) and iron oxide (fe2o3) (see in table 1) (sedmalis et al. 2002). the data of chemical and mineralogical compositions of applied clay as well as the ability to make light weight aggregates was obtained from literature (sedmalis et al. 2002, svinka and lindina 1994, svinka et al. 2011). the xrd analysis indicates the presence of illite, kaolinite and quartz, as well as hematite and trace minerals – orthoclase and microcline in the clay (svinka et al. 2011). the ratio of clay and sewage sludge for selected four optimal compositions mixed from the raw materials s1, s2, s3 and s5 are given in table 2. the mentioned mixtures were created in order to detect the possible volume of each addition for production of dense ceramic composites with exact complex of properties – to create a glassy and crystalline phases during thermal treatment. recycling possibilities of sewage sludge from water purification 55 window glass, whereas others crystallize too readily in an uncontrollable manner resulting in undesirable microstructures. secondly, heat treatment is a critical factor in attaining acceptable and reproducible products (rawlings et al. 2006, suzuki and tanaka 1999). as the main methods for recycling of sewage sludge the powder technology and one-stage thermal treatment for production of glass-ceramic is selected. the raw materials used for the given studies were sewage sludge from drinking water preparation plant and limeless clay from deposit liepa (latvia). the limeless clay is suitable for press powder-mix while it can form the liquid phase during sintering process which is necessary for creation of glassy matrix to incorporate the part of sewage sludge (sedmalis et al. 2002, sedmale 2010, rawlings et al. 2006, svinka et al. 2011). the advantages of this method – it is simple, economically profitable, necessary equipment is available in already running technologies and obtained products usually are characterized with high mechanical strength. 2. methods the information about used raw material clay is based on literature data (svinka and lindina 1994, svinka et al. 2011, sedmalis et al. 2002), while the information concerning the used sewage sludge is based on producer’s data. the mineralogical composition was determined by xrd analysis, while the determination of moisture, organic matter and ash content performed according to the latvian standard (lvs en report 13039:2012). the raw materials were dried for 24 h by 100 o c temperature and the mixtures were created from 60 to 90 wt % of clay and 40 until 10 wt % of sewage sludge. the compositions were milled in mechanic mill retsch rm100 for 1 hour in order to get the powder fraction with particle’s ∅ ≤ 0.5 mm. discoid samples (∅ = 10 mm) were prepared using weber pw-10 hydraulic press by pressure 6 kn (19.1 mpa) and treated thermally in nabertherm electric furnace (max temperature – 1300 o c) with following high-temperature treatment rate: increasing rate 3 °c/min until maximal temperature interval 1100 1180 o c and keeping time by maximal temperature 1 h. the bulk density, water uptake and porosity were measured using standard method (lvs en standard 10545-3:2002). the samples of sewage sludge and sintered glass-ceramic materials made from the already mentioned latvian industrial wastes and clay were analysed by xrd analysis. powdered glassceramic materials were used for xrd patterns, recorded on a rigaku ultima+ x-ray diffractometer with 50ma and 40 kv, cu k α radiation. the mineralogical identifications were made using an xrd pattern database (international centre for diffraction data, icdd). 3. results and discussion investigation of raw materials the sewage sludge contains biogenous elements needed for bacteria’s in the activated sludge – nitrogen, phosphorous, oxygen, carbon and hydrogen, as well as some trace of aluminium (al), while as the coagulant in the water purification process the aluminium sulphate (al 2 (so 4 ) 3 x18h 2 o) was used (data from producer). during the entering into the water the hydrolysis of aluminium takes place which resulted with aluminium hydroxide and its polymers. fig. 1. the xrd pattern for sewage sludge treated at temperature 700 o c abbreviation: q – quartz (sio 2 ) the calculated content of moisture is 84.11 wt %, part of organic matter corresponds to the 55.60 wt %, while the ash content of sewage sludge is 44.03 wt %. fig. 1. the xrd pattern for sewage sludge treated at temperature 700o c abbreviation: q – quartz (sio2 ) 48 table 2. content of raw materials in the waste mixtures components, wt % s1 s2 s3 s4 clay from deposit liepa 90 80 70 60 sewage sludge 10 20 30 40 physical-chemical properties of glass-ceramics fig. 2 shows the increase of thermal shrinkage of all investigated series of mixes versus the increasing temperature of thermal treatment. the highest thermal shrinkage values indicate the mixtures s3 and s4 – 35 and 45%, respectively. the curves of shrinkage for composition s3 and s4 became to be sheerer with temperature 1140 ° c, while the shrinkage curves for compositions s1 and s2 are shallow (fig. 2). the highest bulk density (2.36 – 2.39 g/cm3) shows the composition s1 (with 10 wt % of sewage sludge) in temperature range 1140 – 1180 ° c when probably starts the melting process of some crystalline phases in the clay (see fig. 3). whereas for all compositions the similar increase of bulk density until temperature 1160 ° c could be observed. the increase of bulk density until the maximum 2.28 g/cm3 and subsequent slow decrease (from the maximum 2.28 g/cm3 at 1140 ° c temperature) until 2.25 g/cm3 at temperature 1180 ° c) could be observed for composition s2 containing 20 wt % of sewage sludge (see in table 2). for all other compositions (s1, s3 and s4) the bulk density does not have a maximum, while the curves continue to rise even at the higher temperatures than 1180 ° c (fig. 3). recycling possibilities of sewage sludge from water purification 57 fig. 3. the bulk density of materials versus thermal treatment temperature whereas for all compositions the similar increase of bulk density until temperature 1160 o c could be observed. the increase of bulk density until the maximum 2.28 g/cm 3 and subsequent slow decrease (from the maximum 2.28 g/cm 3 at 1140 o c temperature) until 2.25 g/cm 3 at temperature 1180 o c) could be observed for composition s2 containing 20 wt % of sewage sludge (see in table 2). for all other compositions (s1, s3 and s4) the bulk density does not have a maximum, while the curves continue to rise even at the higher temperatures than 1180 o c (fig. 3). fig. 4. the xrd pattern for glass-ceramic s4 sintered at temperature 1100 o c (left) and 1160 o c (right) abbreviations: q – quartz (sio 2 ), m microcline (kalsi 3 o 8 ), h hematite (fe 2 o 3 ) and c corundum (al 2 o 3 ) in general the mineralogical composition of material s4 for both sintering temperatures – 1100 o c and 1160 o c (fig. 4) show similar crystalline phases – microcline (kalsi 3 o 8 ), quartz (sio 2 ), hematite (fe 2 o 3 ) and corundum (al 2 o 3 ) with insignificant higher peaks of intensity for quartz and hematite for material sintered at temperature 1160 o c (fig. 4 right). the discussions on the chemical and mineralogical composition of liepa deposit clay is given in literature (svinka and lindina 1994, svinka et al. 2011). by the xrd analysis in the untreated clay the illite, kaolinite and quartz, as well as hematite and trace minerals – orthoclase and microcline was detected (svinka et al. 2011). the xrd analysis for sewage sludge treated at temperature 700 o c as the main crystalline phase shows the quartz (see fig. 1). whereas according to the producer’s data in the composition of sewage sludge a big amount of alumina due to coagulation’s agent added during the water purification process is present. thus it could be conclude that aluminium in the composition of mixtures after thermal treatment is not involved into the crystalline structure of material. according to literature data (svinka and lindina 1994, svinka et al. 2011) and results of investigation of sewage sludge, the largest amount of quartz, microcline and hematite could be formed on the basis of hightemperature mineralogical transformation of used clay (sedmalis et al. 2002, svinka et al. 2011), while the microcline and corundum partly were formed probably during the reactions between the clay as a matrix and the sewage sludge with high aluminium and some trace of iron content. the orthoclase and microcline due to their fluxing behaviour could be basis of formation of liquid phase during sintering process resulted with high density during sintering of mixtures (wattanasiriwech and wattanasiriwech 2011). the limeless clay is suitable for press powder-mix while it can form the part of liquid phase during sintering process which is necessary for the creation of glassy phase for incorporation of sewage sludge into the glass matrix (sedmale 2010, rawlings et al. 2006, svinka et al. 2011). the rapid increase of thermal shrinkage of mixtures s3 and s4 by temperatures higher than 1140 o c (fig.2) could be explained with the higher sewage sludge content in those compositions (30% for composition s3 and 40% for composition s4, respectively). probably at these temperatures more liquid phase could be created due to the high content of aluminium and other metals in sludge composition. while for compositions s1 and s2 the fig. 4. the xrd pattern for glass-ceramic s4 sintered at temperature 1100o c (left) and 1160o c (right) abbreviations: q – quartz (sio2 ), m microcline (kalsi3o8 ), h hematite (fe2o3) and c corundum (al2o3) i.rozenstrauha, s. survila, l.krage, m. drille, g. sedmale and i. pastare 56 table 1. chemical composition of applied clay oxides content, wt % al 2 o 3 16.75 sio 2 63.18 cao 0.82 tio 2 0.81 mgo 2.07 fe 2 o 3 7.64 na 2 o 0.14 k 2 o 3.46 organic substances 0.24 loi (1000 o c) 4.89 by the xrd analysis for sewage sludge treated at temperature 700 o c as main crystalline phase the quartz (sio 2 ) was detected (see in fig. 1). the clay used as a matrix for glass-ceramic shows the high amount of silica (sio 2 ), alumina (al 2 o 3 ) and iron oxide (fe 2 o 3 ) (see in table 1) (sedmalis et al. 2002). the data of chemical and mineralogical compositions of applied clay as well as the ability to make light weight aggregates was obtained from literature (sedmalis et al. 2002, svinka and lindina 1994, svinka et al. 2011). the xrd analysis indicates the presence of illite, kaolinite and quartz, as well as hematite and trace minerals – orthoclase and microcline in the clay (svinka et al. 2011). the ratio of clay and sewage sludge for selected four optimal compositions mixed from the raw materials s1, s2, s3 and s5 are given in table 2. table 2. content of raw materials in the waste mixtures components, wt % s1 s2 s3 s4 clay from deposit liepa 90 80 70 60 sewage sludge 10 20 30 40 the mentioned mixtures were created in order to detect the possible volume of each addition for production of dense ceramic composites with exact complex of properties to create a glassy and crystalline phases during thermal treatment. physical-chemical properties of glass-ceramics fig. 2 shows the increase of thermal shrinkage of all investigated series of mixes versus the increasing temperature of thermal treatment. the highest thermal shrinkage values indicate the mixtures s3 and s4 – 35 and 45%, respectively. the curves of shrinkage for composition s3 and s4 became to be sheerer with temperature 1140 o c, while the shrinkage curves for compositions s1 and s2 are shallow (fig. 2). fig. 2. the thermal shrinkage of materials versus thermal treatment temperature the highest bulk density (2.36 – 2.39 g/cm 3 ) shows the composition s1 (with 10 wt % of sewage sludge) in temperature range 1140 – 1180 o c when probably starts the melting process of some crystalline phases in the clay (see fig. 3). fig. 2. the thermal shrinkage of materials versus thermal treatment temperaturerecycling possibilities of sewage sludge from water purification 57 fig. 3. the bulk density of materials versus thermal treatment temperature whereas for all compositions the similar increase of bulk density until temperature 1160 o c could be observed. the increase of bulk density until the maximum 2.28 g/cm 3 and subsequent slow decrease (from the maximum 2.28 g/cm 3 at 1140 o c temperature) until 2.25 g/cm 3 at temperature 1180 o c) could be observed for composition s2 containing 20 wt % of sewage sludge (see in table 2). for all other compositions (s1, s3 and s4) the bulk density does not have a maximum, while the curves continue to rise even at the higher temperatures than 1180 o c (fig. 3). fig. 4. the xrd pattern for glass-ceramic s4 sintered at temperature 1100 o c (left) and 1160 o c (right) abbreviations: q – quartz (sio 2 ), m microcline (kalsi 3 o 8 ), h hematite (fe 2 o 3 ) and c corundum (al 2 o 3 ) in general the mineralogical composition of material s4 for both sintering temperatures – 1100 o c and 1160 o c (fig. 4) show similar crystalline phases – microcline (kalsi 3 o 8 ), quartz (sio 2 ), hematite (fe 2 o 3 ) and corundum (al 2 o 3 ) with insignificant higher peaks of intensity for quartz and hematite for material sintered at temperature 1160 o c (fig. 4 right). the discussions on the chemical and mineralogical composition of liepa deposit clay is given in literature (svinka and lindina 1994, svinka et al. 2011). by the xrd analysis in the untreated clay the illite, kaolinite and quartz, as well as hematite and trace minerals – orthoclase and microcline was detected (svinka et al. 2011). the xrd analysis for sewage sludge treated at temperature 700 o c as the main crystalline phase shows the quartz (see fig. 1). whereas according to the producer’s data in the composition of sewage sludge a big amount of alumina due to coagulation’s agent added during the water purification process is present. thus it could be conclude that aluminium in the composition of mixtures after thermal treatment is not involved into the crystalline structure of material. according to literature data (svinka and lindina 1994, svinka et al. 2011) and results of investigation of sewage sludge, the largest amount of quartz, microcline and hematite could be formed on the basis of hightemperature mineralogical transformation of used clay (sedmalis et al. 2002, svinka et al. 2011), while the microcline and corundum partly were formed probably during the reactions between the clay as a matrix and the sewage sludge with high aluminium and some trace of iron content. the orthoclase and microcline due to their fluxing behaviour could be basis of formation of liquid phase during sintering process resulted with high density during sintering of mixtures (wattanasiriwech and wattanasiriwech 2011). the limeless clay is suitable for press powder-mix while it can form the part of liquid phase during sintering process which is necessary for the creation of glassy phase for incorporation of sewage sludge into the glass matrix (sedmale 2010, rawlings et al. 2006, svinka et al. 2011). the rapid increase of thermal shrinkage of mixtures s3 and s4 by temperatures higher than 1140 o c (fig.2) could be explained with the higher sewage sludge content in those compositions (30% for composition s3 and 40% for composition s4, respectively). probably at these temperatures more liquid phase could be created due to the high content of aluminium and other metals in sludge composition. while for compositions s1 and s2 the fig. 3. the bulk density of materials versus thermal treatment temperature 49 in general the mineralogical composition of material s4 for both sintering temperatures – 1100 ° c and 1160 ° c (fig. 4) show similar crystalline phases – microcline (kalsi3o8), quartz (sio2), hematite (fe2o3) and corundum (al2o3) with insignificant higher peaks of intensity for quartz and hematite for material sintered at temperature 1160 ° c (fig. 4 right). the discussions on the chemical and mineralogical composition of liepa deposit clay is given in literature (svinka and lindina 1994, svinka et al. 2011). by the xrd analysis in the untreated clay the illite, kaolinite and quartz, as well as hematite and trace minerals – orthoclase and microcline was detected (svinka et al. 2011). the xrd analysis for sewage sludge treated at temperature 700 ° c as the main crystalline phase shows the quartz (see fig. 1). whereas according to the producer’s data in the composition of sewage sludge a big amount of alumina due to coagulation’s agent added during the water purification process is present. thus it could be conclude that aluminium in the composition of mixtures after thermal treatment is not involved into the crystalline structure of material. according to literature data (svinka and lindina 1994, svinka et al. 2011) and results of investigation of sewage sludge, the largest amount of quartz, microcline and hematite could be formed on the basis of high-temperature mineralogical transformation of used clay (sedmalis et al. 2002, svinka et al. 2011), while the microcline and corundum partly were formed probably during the reactions between the clay as a matrix and the sewage sludge with high aluminium and some trace of iron content. the orthoclase and microcline due to their fluxing behaviour could be basis of formation of liquid phase during sintering process resulted with high density during sintering of mixtures (wattanasiriwech and wattanasiriwech 2011). the limeless clay is suitable for press powder-mix while it can form the part of liquid phase during sintering process which is necessary for the creation of glassy phase for incorporation of sewage sludge into the glass matrix (sedmale 2010, rawlings et al. 2006, svinka et al. 2011). the rapid increase of thermal shrinkage of mixtures s3 and s4 by temperatures higher than 1140 ° c (fig. 2) could be explained with the higher sewage sludge content in those compositions (30% for composition s3 and 40% for composition s4, respectively). probably at these temperatures more liquid phase could be created due to the high content of aluminium and other metals in sludge composition. while for compositions s1 and s2 the content of sewage sludge is lower therefore the curves is more shallow, which is more suitable for production of dense glass-ceramic due to longer sintering interval (rawlings et al. 2006). the increase of bulk density until the maximum 2.28 g/cm3 at 1140 ° c temperature for composition s2 containing 20 wt % of sewage sludge (see in table 2) shows the beginning of sintering interval of composition, while the slow decrease of bulk density from the temperature 1140 ° c until 1180 ° c (fig. 3) shows the continuing of the sintering interval of composition. this composition s2 according to their presented relations between bulk density and thermal shrinkage could be the optimal for production of glass-ceramics while this shows the similar properties to other previously investigated glass-ceramics (rozenstrauha et al. 2011) and could be suitable for running ceramic’s production technologies without significant changes. for compositions s1, s3 and s4 the bulk density curves does not have a maximum, but they continue to ascend. these processes resulted with high thermal shrinkage for compositions s3 and s4 – 35 until 45% (see figure 2), where the shrinkage curves show rapid increase, which could be explained with the melting of crystalline phases containing alkali metals and vaporisation of volatile elements in the compositions content. in this temperature (from 1140 until 1180 ° c) the amount of liquid phase is probably too high (due to the presence of large amount of sewage sludge 30– 40 wt. %, see in table 2) which results in high thermal shrinkage and subsequent weakness of materials shape of compositions s3 and s4. the results of xrd analysis of series s4 sintered at temperature 1100 ° c indicates the following crystalline phases: microcline (kalsi3o8), hematite (fe2o3), quartz (sio2) and corundum (al2o3) (see figure 4). if to compare the mineralogical composition of series s4 at both sintering temperatures (1100 and 1160 ° c), then insignificant higher intensity peaks of quartz and hematite crystalline phases for materials sintered in temperature 1160 ° c (fig. 4, right) could be mentioned. therefore it could be concluded that the formed crystalline phases in temperature 1100 ° c are stable until the temperature 1160 ° c and starts to melt at higher temperatures. this consequence can be suitable for production of investigated materials with longer sintering temperature interval for composition s4. for further investigations of produced novel materials the mechanical properties tests and studies of microstructure are necessary in order to acquire the suitability of products for building ceramics. 4. conclusions the present study was focused on the recycling of sewage sludge from water purification into the glassceramic materials. the novel glass-ceramic composites were produced from both raw materials – sewage sludge (10 – 40 wt %) and limeless clay (90 – 60 wt %) using a simple technology route – powder technology and sintering during one-stage thermal treatment. the optimal bulk density 2.28 g/cm3 observed for composition s2 containing the 20 wt % of sewage sludge, while the composition with highest content of sewage sludge (40 wt %) resulted with high bulk density ratio 2.30 g/cm3 by temperature 1180 ° c, subsequent increasing of density by higher temperatures until 1180 ° c and at the same time the rapid increase of thermal shrinkage 35 – 45 %. the results of xrd analysis of material s4 sintered at temperature 1100 ° c indicate the following crystalline phases: microcline (kalsi3o8), hematite (fe2o3), quartz (sio2) and corundum (al2o3) which is base for crystalline structure of novel materials. 50 the direction of application of produced glassceramics – suitability for building materials could be better evaluated by microstructure studies and mechanical tests. acknowledgements financial support from state research programme “natural resources” no v7793 part no 1.3. “new ceramic products and technologies” is gratefully acknowledged. references cheilas, a., katsioti, m., georgiades, a., malliou, o., teas, c., haniotakis, e. 2007. impact of hardening conditions on to stabilized/solidfied products of cement–sewage sludgejarosite/alunite. cement & concrete composites, vol. 29, 263–269. chih-huang, w., deng-fong, l., pen-chi, c. 2003. utilization of sludge as brick materials. advances in environmental research. vol. 7, 679–685. ledins, v. ūdensapgāde un kanalizācija (water supply and sewerage). 2007. rtu press, riga, 209 p. lu, y., wu, x., guo, j. biological activity during co-composting of sludge issued from the omw evaporation ponds with poultry manure. physico-chemical characterization of the processed organic matter. 2008. waste management, vol. 28, (8), 1375 1385. lvs en report 10545-3:2002. ceramic tiles – part 3. detection of water absorbtion, apparent porosity, apparent and bulk density. riga, 2002. 6 p. lvs en report 13039:2012. soil improvers and growing media determination of organic matter content and ash. riga, 2012. 5 p. rawlings, r. d., wu j. p., boccaccini a. r. glass-ceramics: their production from wastes. review. 2006. j. mater. sci, springer, vol 41, 733-761. rozenstrauha, i., g sosins, l petersone, l krage, m drille and v filipenkov. 2011. production of glass-ceramics from sewage sludge and waste glass. iop conference series: materials science and engineering, 25 (2011) 012016doi:10.1088/1757-899x/25/1/012016 sedmale g. ceramics. chemistry and technology. 2010. isbn 978-9934-10-065-9, rtu press, riga, 2010. 226 p. sedmalis, u., sperberga, i., sedmale, g. 2002. latvijas minerālās izejvielas un to izmantošana (latvian mineral raw materials and usage of them). 2002. rtu press, riga, 2002. 196 p. shinogi, y., yoshida, h. koizumi, t. 2003. basic characteristics of low–temperature carbon products from waste sludge. 2003. advances in environmental research, 2003. 661 665. suzuki, s., tanaka, m. glass – ceramics from sewage sludge ash. 1997. j. mater. sci. vol 32, 1775 1779. svinka, v., bidermanis, l., svinka, r., lindina, l., cimmers, a., timma, i. 2011. termoķīmiskās reakcijas mālu minerālos šūnu keramikas iegūšanai (thermochemical reactions of clay minerals for production of honeycomb ceramics). 2011. scientific journal of riga technical university, material science and applied chemistry, rtu press, riga, vol. 24, 56-60 svinka, v., lindina, l. 1994. the mineralogical composition of latvian clay and the thermochemical reactions during the firing process. latvian journal of chemistry, vol. 3, 295 – 303. wattanasiriwech, d., wattanasiriwech, s. 2011. fluxing action of illite and microcline in a triaxial porcelain body. journal of the european ceramic society, vol. 31, 1371-1376 received 2012 05 31 accepted after revision 2012 09 03 ineta rozenstrauha – assoc. prof. at riga technical university, department of chemistry, faculty of material science and applied chemistry. main research area: glass-ceramics production from various type of industrial waste. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 264 23943 e-mail: ineta.ro@hotmail.com sergejs survila – student at riga technical university, faculty of material science and applied chemistry, department of general chemistry. main research area: recycling of sewage sludge. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 282 77643 e-mail: sergejs.survila@inbox.lv linda krage – assoc. prof. at riga technical university, department of silicate materials, faculty of material science and applied chemistry. main research area: glass-ceramics, concrete and restoration. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 264 32537 e-mail: linda@ ktf.rtu.lv 51 modris drille – assoc. prof. at riga technical university, department of general chemistry, faculty of material science and applied chemistry. main research area: industrial waste recycling, water purification, analytical chemistry. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 291 65350 e-mail: modris@ktf.rtu.lv gaida sedmale – prof. at riga technical university, department of silicate materials, faculty of material science and applied chemistry. main research area: glassy and ceramic materials. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 264 03286 e-mail: gsedamle@ktf.rtu.lv inese pastare – laboratory assistant at riga water ltd. main research area: water analysis and purification. address: z. a. meierovica blwd.1, riga, lv-1050, latvia. tel.: +371 292 45946 e-mail: inesepastare@inbox.lv 40 darnioji architektūra ir statyba 2013. no. 2(3) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction it is not easy to obtain that the formed concrete surface would be free of air pores, honeycombs and other blemishes. at the moment, the main solution for the removal of air bubbles from the surface of concrete is to use various repairing mortars. unfortunately, they change the color of the natural concrete, this process requires an additional work load and, of course, it is not economic (klovas and dauksys 2011). in the building industry, architects and building owners generally have strict requirements for the quality of concrete surface (lemaire et al. 2005, menard 1999). usually, these requirements mainly concern flatness, tint and the absence of bugholes of concrete surface cib report (1973). the evaluation of concrete surface flatness generally does not pose a problem on the building site. however tint and the quantity of bugholes are factors, which often are being considered by the owners, architects and building contractors. according to the guidelines of: aci 309r (2005), aci 116r (2000), aci 309.1r (2008), the most important factors that influence the concrete surface quality are: 1. failings at the projecting and building processes: ▪ sophisticated concrete laying due to the complicated form of the structure element; ▪ inappropriate assembly and maintenance of the formworks; ▪ inappropriate concrete mixture compositions; ▪ lack or over vibrated concrete mixture; ▪ inappropriate supervision of the concrete hardening process. the distribution analysis of concrete horizontal surface air pores albertas klovas1, mindaugas daukšys1, linas levulis2 1kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania 2jsc “mitnija”. palemono st. 3, lt-52159 kaunas, lithuania *corresponding author: albertas.klovas@ktu.lt http://dx.doi.org/10.5755/j01.sace.2.3.2789 the main aim of this article was to determine blemishes of concrete surface as well as to perform the statistical analysis of pores distribution. the quality of the concrete surfaces in this research depended only on the form’s materials that were as follows: wood impregnated with polymeric oil [wpo], wood covered with rubber [wcr], sawn timber [st], metal [m] and plastic [p] formworks. statistical analysis of the results was made. following parameters of the obtained results were calculated: mean value, dispersion, standard deviation and the coefficient of variation. also maximum and minimum values of experimental results are given. intervals of the experimental results are provided for each specimen with the biggest possibility. keywords: concrete surface quality, formwork, statistical analysis. 2. failings due to the outdated building equipment. 3. failings due to the inappropriate usage of building materials: ▪ undesirable usage of mineral and chemical admixtures; ▪ bad evaluation of different cement characteristics. 4. influence of the aggressive environment. bugholes do not affect the structural integrity of concrete, but their presence causes delays in the production schedule due to the need for proper surface treatment before the structure is considered to be finished (reading 1972, shilstone 1979, stamenkovic 1973). formworks are also very important factor for concrete surface quality. scientists have conducted a research using two different types of formworks: controlled permeability (cp) and not permeable formworks. the results have shown that by using cp formworks the pore diameter (mm) of concrete surface has decreased up to 50 %, porosity (%) – up to 45 %, surface hardness (mpa) has increased up to 70 % and blow-hole ratio has decreased up to 90 % comparing with those concrete surfaces using five layer wood-based formworks (coutinho 2001, price 2000, duggan 1992). international council for building research has provided main guidelines how the concrete may be defined referring the surface quality: (heist et al. 2002) ▪ rough class is provided for surfaces where there is no special requirement for finish; ▪ ordinary class applies to surfaces where appearance, whilst a minor factor, is still of some importance; 41 ▪ elaborate class applies to those with definite requirements for visual appearance; ▪ special class applies to those calling for the highest standards of appearance. ▪ guide to concrete construction (1994) provides the main surface blemishes that could be obtained after the concrete process. ▪ blowholes (sometimes called bug holes) are individual rounded or irregular cavities that are formed against the formwork and become visible when it is stripped. small blowholes (less than 10 mm.) tend to be approximately hemispherical while larger ones are irregular and often expose coarse aggregate particles. they tend to be more prevalent towards the top of concrete placement than at the bottom, due to the increased compaction and static head at the bottom layer of the pour. blowholes are caused by the entrapment of air against the inside face of the formwork. ▪ crazing or craze cracking (sometimes called as map cracking) is a network of fine random surface cracks spaced from 10 to 70 mm apart, dividing the surface up into irregular hexagonal areas. they are always most prominent then the surface has been wet and then dries off, leaving the damp cracks outlined against the dry surface. crazing is caused by the shrinkage of the surface layer relative to the base concrete. ▪ dusting. a dusting floor surface is marked by an accumulation of fine material requiring to be swept up after the floor has been used. dusting of the surface is caused by the surface layer being weak and the matrix not properly bonding the fine aggregate particles (suprenant and malisch 1999). ▪ flaking is where discrete pieces of the surface become detached leaving a rough indentation behind. the pieces are usually flat. scaling should not be confused with flaking. scaling is the delamination of the concrete surface when exposed to freeze-thaw cycles and although the appearance is similar, but the mechanism is different. flaking is caused by inappropriate finishing techniques that seal the surface and trap the water which would otherwise have risen to the surface as bleed water (suprenant and malisch 1998). ▪ honeycombing refers to voids in concrete caused by the mortar not filling the spaces between the coarse aggregate particles. it usually becomes apparent when the formwork is stripped, revealing a rough and stony concrete surface with air voids between the coarse aggregate. honeycombing is caused either by the compaction not having been adequate to cause the mortar to fill the voids between the coarse aggregate, or by holes and gaps in the formwork allowing some of the mortar to drain out of the concrete. the outcome of this article was to find how different formworks influence the quality of concrete surfaces. 2. methods jsc “akmenes cementas” (lithuania) portland cement cem ii/a-ll 42.5 r was used for the test. physical and mechanical properties of portland cement cem ii/all 42.5 r are given at the table 1. kvesu quarry sand with the fraction of 0/4, bulk density of 1550 kg/m3 and fineness module of 1.67 was used as fine aggregate. 0/1 sand fraction ( =ρ 1460 kg/m3, fineness module 2.37) was also used as fine aggregate. gravel with the fraction of 4/16 and bulk density of 1327 kg/m3 was used as coarse aggregate. granulometric composition of aggregates is presented at table 2. concrete mixture composition, presented at table 3, was not designed, but selected according to the recommendations of reinforced concrete producers. plasticizing admixture based on polycarboxylatether muraplast fk 801.1 (mc-bauchemie, germany) was used with the solution density of 1.05 g/ml. the total dosage of admixture– muraplast fk 801.1 was 1.4 % of cement. in addition, the pigment bayferrox (basf, germany) was used for the test. approximately 4 % of pigment in respect to the mass of cement was added. also form release agent was used: ortolan sep 711 (mc-bauchemie, germany). during the research, dry aggregates were used for concrete mixtures. cement and aggregates were dosed by weight while water and chemical admixture were dosed by volume. chemical additives in the form of solutions were mixed with water and used in preparation of concrete mixture. concrete mixture was mixed for 3 minutes in the laboratory in forced type concrete mixer. table 1. physical and mechanical properties of portland cement cem ii/a-ll 42.5 r specific surface area, m2/kg 410 particle density, kg /m3 3050 normal consistency of cement paste, % 26.5 initial setting time, min. 195 compressive strength after 2 days / after 28 days, mpa 27.1/54.0 table 2. granulometric composition of aggregates radius of the sieve’s mesh, mm the amount of poured out material, % sand fraction 0/1 sand fraction 0/4 gravel fraction 4/16 16.0 100.00 100.00 98.80 8.0 100.00 100.00 42.10 4.0 100.00 95.10 4.30 2.0 99.80 81.80 1.00 1.0 99.10 54.60 0.52 0.500 77.40 12.40 0.44 0.250 2.20 0.70 0.36 0.125 0.50 0.30 0.32 0.000 0.00 0.00 0.00 42 table 3. concrete mixture compositions materials measurement concrete mixture composition. materials per 1m3 concrete mixture ba1 cement kg 293 water l 158 course aggregate, gravel 4/16 kg 970 fine aggregate, sand 0/4 kg 733 fine aggregate, sand 0/1 kg 277 superplasticizer, muraplast fk 801.1 (1.4 %) l 4.2 pigment, bayferrox kg 11.7 water and cement ratio – 0.540 five different formworks were used for this research: wood impregnated with polymeric oil [wpo]; wood covered with rubber [wcr]; sawn timber [st]; plastic [p] and metal [m] forms. some of them are presented at fig. 1. fig. 1. formworks that were used for the research dimensions of the different formworks: ▪ wood impregnated with polymeric oil [wpo]: 550 x 300 mm; ▪ wood covered with rubber [wcr]: 400 x 400 mm; ▪ sawn timber formwork [st]: 600 x 300 mm; ▪ plastic formwork [p]: 400 x 400 mm; ▪ metal formwork [m]: 400 x 400 mm. concrete surface area of 300 x 300 mm was evaluated. the irrigation corner of plywood using solvent-based form release agent was established. the test took 6 days in order to check the changing of an angle. the results are presented at table 4. the main idea of this research was to conduct the test with the excessive amount of form release agent which was applied on the formwork. this is the most common mistake which is done by the building contractors, where the form release agent is sprayed on the formwork without removing the excessive amount. the air content of concrete mixture was determined according to lst en 12350-7 standard. flow table test for concrete mixtures was conducted according to lst en 12350-5:2009 standard and density of concrete mixtures – lst en 12350-6. technological properties of concrete mixture used in this research were established as follow: consistency of concrete mixture measured by flow table test rate (525 mm) – f4, air content of concrete mixture – 4.0 %, the density of concrete mixture – 2374 kg/m3. the quantity of fine particles (not exceeding 0.25 mm) was 202.671 kg to 1m3 of concrete mixture. the parameters of vibration table: amplitude – 0.5 mm; frequency – 50 hz. environment conditions: 18 °c of temperature and 65 % of relative humidity. vibration time was seven seconds. “imagej” method provides visual information about the quality of concrete surfaces in respect to the ratio between area of blemishes and whole specimen. all the photographs of this research were taken by the htc hd2 with 5 megapixels camera. photos were taken around 30 cm of distance. “imagej” method: 1. image of the concrete surface is imported into the “imagej” program. in this research, images of around 900 cm2 of area were analyzed; 2. picture is set to the 8bit quality. this is done to highlight the blemishes of the surface (fig. 2); 3. image scale is set to the certain known dimension; 4. image colors are changed into the black and white to highlight the blemishes of the surface; 5. the areas of surface blemishes are calculated. table 4. irrigation corner of solvent-based form release agent 24 h 48 h 72 h 96 h 120 h 144 h 168 h nr. form release agent α 90 – α α 90 – α α 90 – α α 90 – α α 90 – α α 90 – α α 90 – α 1 solvent-based (excessive appl.) 40 50 39 51 43 47 48 42 52 38 59 31 44 46 43 fig. 2. image transformation using “imagej” program 3. results concrete specimens were cured in different formworks for 7 days at temperature of 20±2 oc. the appearance of the specimens is presented at fig. 3. a) concrete specimen cured in wood impregnated with polymeric oil formwork b) concrete specimen cured in wood covered with rubber formwork c) concrete specimen cured in metal formwork d) concrete specimen cured in saw timber formwork e) concrete specimen cured in plastic formwork fig. 3. the appearance of concrete specimens after the curing 44 statistical analysis of the results was made. three casting with each formwork were performed. computer programs “mathcad 15” and “excel 2010” were used. following statistical parameters of blemishes area were calculated: mean value (mv), dispersion (d), standard deviation (sd) and the coefficient of variation (cv). also maximum (max) and minimum (min) values of experimental results are given. the biggest relative frequency of experimental results is provided. the results of the statistical analysis are presented at table 5. according to the information provided at table 5, the size of surface blemishes varies between 1.033 mm2 (formwork – metal) to 17.82 mm2 (formwork – wood covered with rubber). the biggest standard deviation (sd) of surface blemishes area is obtained by using formworks: sawn timber (st) (sd = 3.105 mm2) and wood covered with rubber (wcr) (sd = 2.511 mm2). the most porous (n = 106) concrete surface is obtained by using wood covered with rubber formwork. the deviation of surface pores by size varied from 1.45 mm2 to 3.50 mm2. the smallest surface pore by size was 1.499 mm2 and the biggest one – 17.82 mm2. rubber, as material, does not absorb the excessive oil, therefore many little pores appeared. the least porous (n = 12) surface was obtained by using saw timber formwork. the deviation of surface pores by size varied from 3.95 mm2 to 6.18 mm2. the smallest surface pore by size was 1.721 mm2 and the biggest one – 12.868 mm2. the reason could be that timber absorbed the excessive amount of form release oil. in those places where was the lack of oil, bigger surface blemishes appeared. the establishment of surface pores quantity helps to evaluate the concrete quality more accurately. in nowadays, in lithuania only old standard gost 13015.0-83 is being used, where the evaluation factor is the size of blemishes, but there is nothing about the quantity of surface defects. 4. conclusions 1. open sourced computer program “imagej” can be used for the evaluation of concrete surface quality by table 5 statistical analysis of the experimental results formworks parameters wpo wcr st p m n 59 106 12 45 70 mv 4.203 4.155 4.867 1.728 2.133 d 3.665 6.305 9.683 0.456 0.535 sd 1.914 2.511 3.105 0.675 0.732 cv 0.456 0.604 0.638 0.391 0.343 min 1.784 1.499 1.721 1.065 1.033 max 11.230 17.82 12.868 4.717 4.65 rf/i 0.322/ [3.157; 4.530) 0.557/ [1.45; 3.50) 0.500/ [3.95; 6.18) 0.556/ [1.065; 1.627) 0.314/ [1.54; 2.048) calculating the quantity and establishing the dimensions of blowholes, air pores and honeycombs. 2. the most porous concrete surface is obtained by using wood covered with rubber formwork (n = 106). the excessive amount of form release agent was not cleaned from the surface of the formwork and the surface material did not absorb it. 3. the least porous concrete surface is obtained by using sawn timber formwork (n = 12). at this case, the excessive amount of form release agent was absorbed by the timber. 4. the smallest concrete surface pores are obtained by using formwork covered with plastic (referring the distribution of the pores), on the other hand, the biggest pores are obtained by using formwork with the rubber surface material. references aci 309r. guide of consolidation of concrete. 2005. aci committee 309, technical committee document 309r-05 2005, 35. aci 116r. cement and concrete terminology. 2000. american concrete institute. 2000, 73. aci 309.1r. behavior of fresh concrete during vibration. 2008. aci committee 309, technical committee document 309. 1r-08. 2008, 18. cib report no. 24, commission w29. 1973. tolerances on blemishes of concrete, 1973. coutinho, j. s. the effect of controlled permeability formwork (cpf) on white concrete. 2001. aci materials journal. vol. 98. no. 2. 2001, 148–171. duggan, t. enhancing concrete durability using controlled permeability formworks. 1992. 17th conference on our world in concrete and structures. singapure, august 1992: pp. 57–62. klovas, a., daukšys., m. 2011. apdailinio betono paviršiaus kokybė ir defektai // statyba ir architektūra: jaunųjų mokslininkų konferencijos pranešimų medžiaga / kauno technologijos universitetas. kaunas: technologija, 2011. isbn 9786090202555, 99–108. [quality and defects of the decorative concrete surface // civil engineering and architecture: conference of the young scientists, proceedings . 45 / kaunas university of technology. kaunas: technology, 2011. isbn 9786090202555, 99–108] lemaire, g., escadeillas ,g., ringot, e. 2005. evaluating concrete surfaces using an image analysis process. construction and building materials 19 2005, 604 – 611. http://dx.doi.org/10.1016/j.conbuildmat.2005.01.025 menard, j. p. 1999. la qualite pour tous les usages. construction moderne 101 1999, 12. [quality of all uses. construction modern 101. 1999, 12. price, w. f. controlled permeability formwork. 2000. ciria report c511. 2000, 102. reading, t. j. the bug hole problem. 1972 aci journal, proceedings v. 69, no. 22, nov. 1972, 165–177. stamenkovic, h. surface voids can be controlled. 1973. concrete construction, v. 18, no. 12, dec. 1973, 597–598. suprenant, b. a., malisch, w. r. 1998. diagnosing slab delamination. concrete construction january, february and march,1998. suprenant, b. a., malisch, w. r. 1999. sealing effects of finishing tools. concrete construction september 1999, 39–43. shilstone, j. m. surface blemishes in formed concrete.1979. concrete construction, v. 24, no. 11, nov. 1979, 719 and 765. heist, t. c., kaden, r. a., martin, r., meza p. standard specifications for tolerances for concrete construction and materials (aci 117-90) 2002. reported by aci committee 117. 2002. received 2012 11 27 accepted after revision 2013 03 22 albertas klovas – ph.d. student at kaunas university of technology, department of civil engineering technologies. main research area: concrete mixture rheological properties, formed concrete surface quality. address: studentu st. 48, lt-51367, kaunas, lithuania. tel.: +370 619 13266 e-mail: albertas.klovas@ktu.lt mindaugas daukšys – assoc. professor at kaunas university of technology, department of civil engineering technologies. main research area: concrete mixture rheological properties, formed concrete surface quality. address: studentu st. 48, lt-51367, kaunas, lithuania. tel.: +370 37 300479 e-mail: mindaugas.dauksys@ktu.lt linas levulis – quality inspector at jsc “mitnija”. main research area: concrete mixture rheological properties, formed concrete surface quality. address: palemono st. 3, kaunas, lithuania. 29 darnioji architektūra ir statyba 2013. no. 1(2) journal of sustainable architecture and civil engineering issn 2029–9990 space syntax analysis of kaunas: some methodological aspects kęstutis zaleckis*, irina matijošaitienė kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania * corresponding author: kestutis.zaleckis@ktu.lt http://dx.doi.org/10.5755/j01.sace.1.2.2791 space syntax analysis is a well known method. despite the fact of its wide usage some improvements could be offered. while preparing axial map of kaunas it was noted that one single axial map cannot be used for evaluation of global and local integration if the correct results are expected. the possibility to use different maps for evaluation of global and local integration in kaunas is discussed in the article. additional arguments for usage of the concept of continuity lines are presented. the offer to not limit the axial map of the city to formal administrative border of the municipality is explained. keywords: space syntax, axial maps, pedestrian routes, continuity lines, kaunas, lithuania. 1. introduction city is a complex organism and as such it requires complex methods of investigation. complex investigation should consider all levels of urban reality and its social, economic, cultural dimensions. space syntax represents one of the complex methods for urban investigation (hillier b., 2007) because it focusses not on the spatial characteristics itself but on the social uses of the space. in this way the method integrates spatial, social, economic, cultural dimensions. during the preparatory stage of investigation of kaunas spatial structure and its influence on security of inhabitants the following important aspects were noted: ▪ many contemporary cities function as complexes of autonomous subsystems from the point of view of transportation because of the separation of pedestrian and car traffic; ▪ big number of single streets cannot be represented by one single axis because of the curved lines; ▪ formal borders of the city do not represent a real urban system. ▪ the following problems or discrepancy between the formal methodology of space syntax and real situation appear here: ▪ a single axial map for a city is created traditionally. two important features are analyzed on the base of the map: global integration and local integration. it could be concluded that the first one is more focused on the public and private car transport. the second one, because of traditionally used distances or number of steps, is more focused on pedestrian connections. global integration measures accessibility of all axes from all other axes of the system. axes of public and private car transport are the most actual here. pedestrian routes as used within the limited distances are not so important for the global integration. if the map is based on the register of the formal streets then many pedestrian axes are not considered too. when the local integration is measured on the base of distance or the number of conditional steps, some axes of transportation could be excluded as not accessible for the pedestrians, e.g. transport tunnels in the city, transit highways, etc. significance of the above mentioned aspects and existence of at least two autonomous networks of transportation in the city could be illustrated by the presented results of investigation: 17 percent of travels in kaunas are made by walking, 60 percent by public transport, and 23 percent by private cars (vį transporto et al. 2007). it is logical to conclude that different types of travelling are used when going to different destinations, e.g. walking to local center of neighborhood, taking a bus or private car to the city center, taking a private car to suburban shopping mall, etc. of course the bigger part of the axes for the global and local integration maps are the same, but quite significant number of mono-functional axes should be taken into consideration. the fact of existence of separated traffic networks could be illustrated by the notice of the existence of streets and roads as two different types of transit spaces in the modern city. the street could be described as a space that integrates pedestrians, traffic, various cultural and social activities. creation of the streets as spaces suitable for street culture is one of the main aims of new urbanism. road as a transit space intended for cars appeared as the result of modern urbanism and monofunctional zoning of a city. in wider context the fact of partially separated networks of transportation demonstrates 30 the fact of fragmentation of the contemporary cityscape at the all levels of its existence: appearance of white spots in the image of the city (zaleckis 2002), loss of compositional integrity and a-local functional connections, caused by web technologies in the matterscape, increased amount of logical asymmetry in the cityscape (zaleckis 2011), asymmetry, etc. in general it means that contemporary city functions as few quite autonomous sub-systems that are connected not in all points. in such a case creation of one axial map of the city is not correct. significant influence of pedestrian connections on the essential qualities of urban structure was proved by investigations in kaunas downtown area (zaleckis et al, 2012). ▪ formal administrative borders of the city do not reflect the real urban integration as it was mentioned above. in kaunas case the number of bridges and highways outside the city borders (e.g. vilnius-klaipeda road, via baltica, southern bypass) in fact are functioning as a part of the inner urban network of the city. appearance of the features of the peripheral city confirms that fact. at the same time the big suburban settlements as garliava and sargenai are functionally and compositionally integrated into the cityscape of kaunas but formally they must be excluded from the axial map because they are outside of the administrative borders of municipality. ▪ in space syntax analysis the curved streets are shown as a number of direct axes. the above mentioned fact is true even for such obviously integral and the most straight long street of kaunas as savanoriai prospect. in many cases the cut of the street into separate axes do not correspond to reality as a big part of curved streets function as single units in the mentalscape or matterscape of kaunas. proposals: ▪ the two different axial maps should be created for the analysis of global and local integration of the city. map of the local integration should include spaces of the public and semi-public transit pedestrian spaces. at the same time axes that are not accessible for pedestrians and public transport should be excluded from this map. ▪ axial map should not be limited to the formal administrative borders of the city; closely integrated suburban parts and roads should be included in the map; ▪ the aggregation of the segments of curved streets of the city should be respected in the axial maps. in fact it could be done by introduction of continuity lines. according to figueiredo “…the notion of continuity is already embedded in the axial system“ (figueiredo et al. 2004) and the continuity lines represent the chosen movement roads with the higher percent of probability. the aim of the article is to prove or reject the above mentioned proposals. kaunas as one of the objects of investigation within the project is chosen as a laboratory for this task. 2. methods space syntax method is used as the basic method in presented research. two different axial maps of kaunas are created. various characteristics of the maps are compared between themselves and validated for the correspondence to the observed facts of urban life of kaunas. the final conclusion on the acceptance or rejection of the above mentioned proposals is made on the base of the research results. mindwalk software was used for syntax analysis. 3. results the first question could be formulated as following: will the quantitative changes between the axial map without pedestrian routes and with pedestrian routes be significant enough to consider it? to receive the answer two axial maps of kaunas were created. axial map 1 with only formal streets included (fig. 1). axial map 2: the pedestrian routes were included and axes not accessible for pedestrians and public transport were excluded (fig. 2). area of the both maps covered suburban territories that are functionally and compositionally integrated into the city. pedestrian axes embraced the following: ▪ spaces of the courtyards of the modernistic districts in silainiai, kalnieciai, eiguliai, dainava; ▪ pedestrian axes in the parks and city forests; ▪ pedestrian bridges. fig. 1. axial map of kaunas with only formal streets included pedestrian axes in the courtyards of old town and new town were not considered because of the ongoing process of restitution and tendency to close the private spaces for the pedestrian transit in these parts of the city. axes excluded from the map 2: ▪ via baltica; ▪ highway vilnius-klaipeda; ▪ parts of the southern bypass. there were identified 9607 axes in the first map (fig. 1) and 10298 axes in the second map (fig. 2.) the total number of axes in kaunas has increased by 7 percent. if subtracted axes from the map 2 are taken into consideration then pedestrian axes can make up to 10 percent of all axes in the city. having in mind a part of pedestrian journeys in kaunas (17 percent) it is a significant change at the city level. its significance for local integration is even higher because of the concentration of axes in few areas. 31 fig. 2. axial map of kaunas with pedestrian axes included. concentration areas of the pedestrian axes could be identified by the darker zones is the quantitative change reflected in quantitative qualities of axial map? do these changes correspond to the observed processes in kaunas? depth values of the both maps were compared in the beginning of quantitative analysis. visually there were no significant changes at the city level but maximal depth of all system was increased from 67 to 70 when pedestrian axes were added. having in mind relatively small number of added axes the change is quite big. in concentration areas the depth of the territory was increased by 5-7 points. the changes of the depth values reflect an observed specialized, disaggregated use of the public spaces of modernistic districts. local integration values were analyzed in the second step. radius was measured by 3 conditional steps or changes of the direction of the paths. significant changes were noted in the modernistic districts in the streets with a higher concentration of commercial and public buildings, e.g.: local integration value of baltu prospect increased from 2.7556 to 3.21, baltijos street – from 2.4173 to 3.17. at the same time control values of baltu prospect decreased from 4.575 to 3.8528, baltijos street – from 4.111 to 2.924. the similar changes could be seen in the all main streets of modernistic districts. segment of partizanu street and siaures prospect (local integration 3.3005 without pedestrian axes and 3.9628 with pedestrian axes) appeared as clearly expressed local centers. the last change represent quite well in reality observed attractiveness of siaures prospect for various commercial activities even if it is located at the border of the city. interesting fact if analyzing the changes of control values: for siaures prospect it increased from 6.6742 to 14.4861 with pedestrian axes added. if comparing situation with above analyzed streets in silainiai (baltu and baltijos streets) the differences could be explained by configuration of pedestrian routes: courtyards in silainiai are more closed and have limited connections to the streets surrounding blocks; in kalnieciai, because of the original spatial design, they are more oriented towards siaurės prospect and other streets. ukmerges street is a minor street in kalnieciai where a few cafes, local community and recreation center with a pool and new shop are located. its integration values increase from 1.4136 to 2.3473. in general, the identified changes quite well represent the real bigger attractiveness of the above mentioned streets as local linear centers or main streets of the neighborhoods and real use of the courtyards for pedestrian transit. as it could be seen in the fig. 3, significant part of the new pedestrian axes is included into 5 percent of all axes with the highest local integration values. it demonstrates significance of the mentioned pedestrian routes for the local neighborhoods and could be proved by the intensive use of these routes while walking to neighborhood centers, shops, etc. it even was intended in the original design of the modernistic district, e.g. in kalnieciai the shopping centers as vitebskas (now iki) or kalnieciai were reachable by walking and practically without usage of transport roads. the same applies for the public spaces as cecenijos square. the maximal local integration value in the city increased from 4.5512 to 4.5746 with pedestrian axes added. the lowest mark remains the same 0.333. the change of the local integration values of the main streets of the modernistic districts is exceeding the common change of the background. at the same time two important axes of kaunas – savanoriai and veiveriu prospects remain the dominant axes of local and global integration in both maps. it coincides with in reality observed multi-functionality of these axes as the central places of the highest rank. if the theory of central places by christaller is applied to the containment of the city then the above mentioned phenomenon could be explained in its terms: central places of the higher rank perform all functions of the central place of the lower rank and additional functions (leslie 1984). note not directly related to the topic of this article: may be the coincidence of high values of the global and local integration can help to identify the central places of the highest rank in the city? of course such a statement requires a separate investigation. fig. 3. local integration map with pedestrian axes (5 percent of the axes with the highest values are shown in black) 32 fig. 4. local integration map without pedestrian axes (5 percent of the axes with the highest values are shown in black) in both cases (with and without pedestrian axes) the fast choice map remains the same. it corresponds to the local significance of the pedestrian axes and their little influence on city traffic. there are around 1500 streets in kaunas (vį transporto et. al. 2007 ) and 9607 axes in the map. as it was mentioned above, even practically direct streets as savanoriu prospect, according to the rules for axial map making, should be broken into few axes. the human perception plays a very important role when choosing a road for transformation and the big part of the curved streets are percepted and used as integral axes (figueiredo et al. 2004). because of this, the concept of continuity lines was introduced into the axial map. according to l. figueiredo and the mindwalk options the angle smaller than 35 degrees is not percept by us as a change of direction. axes in kaunas map were merged into continuity lines according to the above mentioned criterion. as a result the number of axes in the map was reduced twice: from 9607 to 4812. examples of aggregated continuity fig. 5. proposed continuity lines (shown in black) lines: savanoriai prospect, vilnius street, laisves avenue together with gertrudos street, siaurės prospect, highways around kaunas, karaliaus mindaugo prospect, etc. it looks that the result reflects human perception of kaunas more correctly, but the question till remains open: could be some additional arguments found for the usage of continuity lines in kaunas map? global integration with and without continuity lines was calculated. the obvious differences could be noted between the fig 6 and fig. 7: ▪ there clear zones of integration could be seen in the map without continuity lines; single streets are highlighted in the map with continuity lines. in the first map some minor streets of the local significance are competing with the main streets of the city, e.g.: the value of global integration of ausros street differs from savanoriai prospect only by 0.033 points (0.4743-0.4413=0.033). it means that streets are practically of the same significance for the city. the difference is more realistic in the map with continuity lines: 1.7391-1.2994=0.4397. ▪ integration values of the highways around kaunas are much higher in the map with continuity lines: for via baltica it increased from 0.3803 to 1.9629, for the south roundabout from 0.4156 to 1.907, etc. these changes reflect few in reality observed processes. the first one: active usage of roundabouts not only by transit but by inner transport of the city too. the second one: higher integration values correlate with appearance of suburban shopping malls and other big commercial objects and new housing developments in giraite, sargenai, kleboniskis, ramuciai as elements of peripheral city. ▪ global integration values in the map with continuity lines are falling down in the area around vyduno avenue, new town, old town significantly. it represents these relatively quiet (in the terms of traffic) urban pockets of the city more correctly. ▪ without the continuity lines the most controlling axes in kaunas are veiveriai and savanoriai prospects. in the map with continuity lines the roundabouts become important players here too. control values of the above mentioned roundabouts are much higher in the second case. it corresponds well to the role of these axes as distribution lines of the city. ▪ depth analysis of the global map reflects the significance of integrating roundabouts for creation of the shallow zones around the city. as it was mentioned above the present centers of the peripheral city confirm usage of these axes for global purposes of the city. ▪ local integration values in the map with continuity lines are more correct: the real local axial centers or main streets as zemaiciu street, taikos prospect, kalantos street, raudondvario street and others have the significantly higher values of integration if compared to the surrounding contexts. 33 fig. 6. global integration map without continuity lines (5 percent of the axes with the highest values are shown in black, black dots mark two level crossings) fig. 7. global integration map with continuity lines (5 percent of the axes with the highest values are shown in black, black dots mark two level crossings) ▪ when calculating the aggregation degree of the city with proposed continuity lines the results are following: the aggregation degree without pedestrian axes is equal 0.6832; the aggregation degree with pedestrian axes is equal 0.6292. in both cases it is quite high and according to the urban network toponomy by figueiredo (figueiredo et al. 2007) marks grid type of the city. the increased depth of some areas demonstrates movement towards less aggregated tree type of the urban network in the city. the tree type structure is peculiar for the deep spaces of semi-public courtyards of the modernistic districts. important note: the lower aggregation degree is calculated for the map with the bigger number of axes. it would be logical to predict the opposite situation because in the bigger number of axes the bigger number of continuity lines could be expected. in this case the lower aggregation degree reflects the quality of the spaces of modernistic districts in the city. 4. discussion the received results were validated by the correspondence to the various urban processes in kaunas. can we say that it will be true in all other cases? if speaking about two axial maps with and without pedestrian axes it can give the similar results in the city with quite significant amount of pedestrian axes that do not correspond to axes of transportation. e.g. big territories planned in modernistic manner give a strong argument for creation of two separate maps. new urbanism (apa 2006) tends to integrate pedestrian and car transport. the case of usage of two maps would be obsolete. the same would be true for the analysis of the medieval or 19th century urbanism. in general we can conclude that offer to make two axial maps is the most actual for the cities that were touched significantly by soviet modernistic urbanism. despite the limited actuality various forms of walkable urbanism can call for the suggested improvement of space syntax analysis. the need to create special axial map with pedestrian axes could be very important for the analysis of relations between spatial structure and crimes too, as different parkways, courtyards and other deeper spaces can attract potential criminals. the idea of continuity lines is offered by l. figueiredo. despite the strong supporting arguments it is not very often used in space syntax analysis. the analysis of kaunas gives a strong support for the usage of this idea. interesting note: combination of axial analysis with and without continuity lines may can help to identify the limits of integral corridors of new urbanism. such idea appeared when comparing two maps: single dominant axes are highlighted when continuity lines are modeled in the axial map; without the continuity lines the same integrating axes (e.g. savanoriai or veiveriai prospects) are shown as parts of the clear zones of high global integration. 5. conclusions for kaunas and probably other contemporary cities with big enough percentage of pedestrian axes, it would be more correct to create two axial maps: one for global integration and one for local integration. the map of the local integration should include axes of the public and semi-public pedestrian transit spaces. at the same time axes that are not accessible for pedestrians and public transport should be excluded from this map. the map of the global integration should include all streets and roads used by the car transport. the axial map should not be limited to the formal administrative borders of the city. it should include suburban areas that are functionally and compositionally closely related to the city. the role of the roundabouts around kaunas proved this statement. the integration of curved streets of the city should be respected in the axial maps. in fact it could be done by more active usage of continuity lines. 34 suggested improvements in kaunas case helped to do the following: to identify the main axes of global and local integration more precisely; to evaluate the depth of the map more correctly; to reflect the real street network in more accurate ways, etc. it was validated by the observed real processes of urban life. acknowledgment the research represented in this article was financed by research council of lithuania. agreement no sin– 08/2012. projektą, kurio metu atliktas straipsnyje pristatomas tyrimas, finansavo lietuvos mokslo taryba. sutarties nr. sin–08/2012. references american planning association. 2006. planning and urban design standards. john wiley & sons, inc. figueiredo l., amorim l. 2004. continuity lines: aggregating axial lines to predict vehicular movement patterns. proceedings of the third great asian streets symposium, singapore, national university of singapore. figueiredo l., amorim l. 2007. decoding the urban grid or why cities are neither trees nor perfect grids. .proceedings of the 6th international space syntax symposium, i̇stanbul, 1–16. hillier b. 2007. space is the machine: a configurational theory of architecture. london: space syntax. leslie j. k. 1984. central place theory (scientific geography series). thousand oaks: sage publications. vį transporto ir kelių tyrimo institutas, vgtu teritoriju planavimo mokslo institutas. 2007. kauno miesto dviračių takų specialusis planas [special plan for bicycle routes in kaunas]. zaleckis k. 2002. kai kurie teoriniai ir praktiniai bendrai suvokiamo ir įsivaizduojamo miesto vaizdo nustatymo klausimai. urbanistika ir architektūra = town planning and architecture, 26 (2), 96–106. zaleckis k. 2011. globalizacijos atspindžiai miesto kūne: keletas įžvalgų. logos : religijos, filosofijos, komparatyvistikos ir meno žurnalas, 66, 142–152. zaleckis, k., matijošaitienė i. 2012. hidden urban revolution in kaunas downtown area: 1935-1988-2011. eight international space syntax symposium, january 3-6, 2012, santiago de chile, chile : proceedings, santiago de chile, pontificia universidad católica de chile, 1–16. received 2012 11 07 accepted after revision 2013 01 09 kęstutis zaleckis – professor at kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management. main research areas: urban genotype and phenotype, military architecture, urban history. address: kaunas university of technology, faculty of civil engineering and architecture, studentu g. 48, lt-51367, kaunas, lithuania. tel.: +370 616 28902 e-mail: kestutis.zaleckis@ktu.lt irina matijošaitienė – lecturer at kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management. main research areas: road and urban landscape, space syntax, kansei engineering, hedonomics, ergonomics, statistics. address: kaunas university of technology, faculty of civil engineering and architecture, studentu g. 48, lt-51367, kaunas, lithuania. tel.: +370 606 88819 e-mail: irina.matijosaitiene@ktu.lt 65 journal of sustainable architecture and civil engineering 2020/1/26 corresponding author: rui.cardoso@ubi.pt strengthening haussmannian and ski resorts hotels wall openings with steel beams and steel portal frames received 2019/08/26 accepted after revision 2020/02/01 journal of sustainable architecture and civil engineering vol. 1 / no. 26 / 2020 pp. 65-73 doi 10.5755/j01.sace.26.1.24084 strengthening haussmannian and ski resorts hotels wall openings with steel beams and steel portal frames jsace 1/26 http://dx.doi.org/10.5755/j01.sace.26.1.24084 rui cardoso ph.d, c-made, beira interior university, civil engineering and architecture faculty, 6201-001 covilha, portugal introduction existing structures must be adapted to comply with current standards or for space efficiency requirements. this adaptation may include the need to create openings in existing walls. in load-bearing walls, the introduction of openings modifies locally the loading path, therefore the opening needs to be strengthened. several strengthening techniques can be applied. in this paper, two strengthening practice solutions, based on the introduction of steel beams and steel portal frames currently applied in haussmanian buildings and french alps ski resorts hotels, are described. those practice solutions can be applied to openings in walls with different materials and thicknesses and for a high variety of loads, presenting acceptable results along time. the knowledge presented in this work is intended to give guidance to strengthening guidelines definition and at the same time to support and encourage the development of innovating strengthening techniques. keywords: concrete wall, masonry wall, openings, strengthening, rehabilitation. along time, existing structures are subjected to functional modifications since they have to be adapted to comply with current living standards or space efficiency requirements. such modification may include the addition of windows or doors, openings enlargement and new paths for ventilation and heating systems. all of which, requiring openings to be cut into existing structural walls, (popescu, 2015). this operation can be easily achieved when the wall does not have a load-bearing function, as partition walls, nevertheless, when the walls are load-bearing, creating or enlarging openings in walls changes the load path within the wall and weaken the structure, adversely influencing its behavior, (popescu et al. 2015), (seddon, 1956). a new load path is established and the wall sections adjacent to the opening bear higher loads and the remaining lintel, if existing, is subjected to flexion. since it is expected that the structural elements located in this new path have not been initially designed to withstand those news loads, an appropriate strengthening structure is required to restore the initial load-bearing wall strength, (mohamed et al. 2013). a diversity of strengthening solutions can be applied, such as external composites, externally bonded steel, textile reinforced mortar, section thickness enlargement or by means of a lintel or a portal frame using concrete or steel members or a combination of those previous techniques, (albert et al. 2001), (engel, 2019), (delatte, 2009). nevertheless, currently there is a lack of normative guidelines related to opening strengthening. this paper is focused in the description of a wall opening strengthening technique currently applied in the savoie and haute savoie departments in france and in the haussmann buildings located in paris journal of sustainable architecture and civil engineering 2020/1/26 66 (cardoso et al, 2018, 2019). this technique is based in the introduction of steel beams and steel portal frames in the opening vicinity. the description is based on engineering design work carried by the author at stebat engineering design office based at albertville, france, (cardoso, 2018-a), 2018b)). the result is an original and innovating technical note, which fills an existing gap between construction practices and research and development. the author strongly believes this work will give appropriate orientations in the development of normative strengthening guidelines, supporting the development of innovating strengthening techniques and practices involving sustainability concerns and allowing further knowledge in heritage rehabilitation and strengthening. the organization of the paper is the following: firstly, some backgrounds on wall openings strength and design is delivered, subsequently the strengthening technique is described by means of practices applications, and finally, some conclusions are indicated. wall openings strength and design when loaded vertically, the strength of a wall depends on three main parameters. first, the boundary conditions defined by the number of restrained sides: two, three or four sides. the higher quantity of restrained sides reduces the wall’s deformations, increase its ultimate strength and have a dominant influence on cracking patterns and failure modes. second, the slenderness defining or not a buckling mode, (saheb and desayi, 1990). third, the reinforcement ratio, increasing the ultimate strength, particularly if the reinforcement is placed on both sides of the wall, (fragomeni and mendis, 1997). a lot of research efforts have been done regarding axially loaded walls and to the authors’ knowledge, the design of axially loaded walls is essentially based on column theory. nevertheless when load-bearing walls contain openings, these are a source of weakness and can size-dependently reduce the structures’ stiffness and load-bearing capacity, (mohammed et al. 2013). additionally, the design codes that have been reviewed (aci 2008), (aci 2011), (as 2009), (csa 2004), (ecs 2004), (ecs 2005) do not provide design equations to walls with openings. only some guidelines are provided in the australian and european standards (as3600 2009, ecs 2004), stating that if, simultaneously, the wall is restrained on all sides and enclose an opening with an area less than 1/10 of the total wall area and the height of the opening is less than 1/3 of the wall height, then the effects of this opening on the axial strength can be neglected. a work from (popescu, 2015) indicates that 25% and 50% reductions in the cross-sectional area of the concrete wall caused by the introduction of small openings and large openings reduces its load carrying capacity by nearly 36% and 50%, respectively. for the above-mentioned reasons, when designing concrete or masonry walls with openings, engineers tend to adopt a simplified method consisting in defining a simple design model constituted by a portal frame, fig. 1-a), or isolated columns, fig. 1-b). the ultimate load is governed by the column or lintel beam failure enclosing fig. 1 opening design models innovating technical note, which fills an existing gap between construction practices and research and development. the author strongly believes this work will give appropriate orientations in the development of normative strengthening guidelines, supporting the development of innovating strengthening techniques and practices involving sustainability concerns and allowing further knowledge in heritage rehabilitation and strengthening. the organization of the paper is the following: firstly, some backgrounds on wall openings strength and design is delivered, subsequently the strengthening technique is described by means of practices applications, and finally, some conclusions are indicated. 2. wall openings strength and design when loaded vertically, the strength of a wall depends on three main parameters. first, the boundary conditions defined by the number of restrained sides: two, three or four sides. the higher quantity of restrained sides reduces the wall’s deformations, increase its ultimate strength and have a dominant influence on cracking patterns and failure modes. second, the slenderness defining or not a buckling mode, (saheb and desayi, 1990). third, the reinforcement ratio, increasing the ultimate strength, particularly if the reinforcement is placed on both sides of the wall, (fragomeni and mendis, 1997). a lot of research efforts have been done regarding axially loaded walls and to the authors’ knowledge, the design of axially loaded walls is essentially based on column theory. nevertheless when load-bearing walls contain openings, these are a source of weakness and can size-dependently reduce the structures’ stiffness and load-bearing capacity, (mohammed et al. 2013). additionally, the design codes that have been reviewed (aci 2008), (aci 2011), (as 2009), (csa 2004), (ecs 2004), (ecs 2005) do not provide design equations to walls with openings. only some guidelines are provided in the australian and european standards (as3600 2009, ecs 2004), stating that if, simultaneously, the wall is restrained on all sides and enclose an opening with an area less than 1/10 of the total wall area and the height of the opening is less than 1/3 of the wall height, then the effects of this opening on the axial strength can be neglected. a work from (popescu, 2015) indicates that 25% and 50% reductions in the cross-sectional area of the concrete wall caused by the introduction of small openings and large openings reduces its load carrying capacity by nearly 36% and 50%, respectively. for the above-mentioned reasons, when designing concrete or masonry walls with openings, engineers tend to adopt a simplified method consisting in defining a simple design model constituted by a portal frame, fig. 1-a), or isolated columns, fig. 1-b). the ultimate load is governed by the column or lintel beam failure enclosing the opening. this method provides acceptable results in construction practices, but it is overly conservative. furthermore, the design codes reviewed do not provide any strengthening design guidelines or even strengthening recommendations. in construction practices the load part resisted by the strengthening structure is evaluate following simple engineering judgment, experimental and numerical research is needed to quantify correctly the load resisted by the strengthening components and by the existing wall. opening length opening heigth lintel beam column column opening heigth opening length column column a) opening design portal frame model b) opening design column model fig. 1. opening design models innovating technical note, which fills an existing gap between construction practices and research and development. the author strongly believes this work will give appropriate orientations in the development of normative strengthening guidelines, supporting the development of innovating strengthening techniques and practices involving sustainability concerns and allowing further knowledge in heritage rehabilitation and strengthening. the organization of the paper is the following: firstly, some backgrounds on wall openings strength and design is delivered, subsequently the strengthening technique is described by means of practices applications, and finally, some conclusions are indicated. 2. wall openings strength and design when loaded vertically, the strength of a wall depends on three main parameters. first, the boundary conditions defined by the number of restrained sides: two, three or four sides. the higher quantity of restrained sides reduces the wall’s deformations, increase its ultimate strength and have a dominant influence on cracking patterns and failure modes. second, the slenderness defining or not a buckling mode, (saheb and desayi, 1990). third, the reinforcement ratio, increasing the ultimate strength, particularly if the reinforcement is placed on both sides of the wall, (fragomeni and mendis, 1997). a lot of research efforts have been done regarding axially loaded walls and to the authors’ knowledge, the design of axially loaded walls is essentially based on column theory. nevertheless when load-bearing walls contain openings, these are a source of weakness and can size-dependently reduce the structures’ stiffness and load-bearing capacity, (mohammed et al. 2013). additionally, the design codes that have been reviewed (aci 2008), (aci 2011), (as 2009), (csa 2004), (ecs 2004), (ecs 2005) do not provide design equations to walls with openings. only some guidelines are provided in the australian and european standards (as3600 2009, ecs 2004), stating that if, simultaneously, the wall is restrained on all sides and enclose an opening with an area less than 1/10 of the total wall area and the height of the opening is less than 1/3 of the wall height, then the effects of this opening on the axial strength can be neglected. a work from (popescu, 2015) indicates that 25% and 50% reductions in the cross-sectional area of the concrete wall caused by the introduction of small openings and large openings reduces its load carrying capacity by nearly 36% and 50%, respectively. for the above-mentioned reasons, when designing concrete or masonry walls with openings, engineers tend to adopt a simplified method consisting in defining a simple design model constituted by a portal frame, fig. 1-a), or isolated columns, fig. 1-b). the ultimate load is governed by the column or lintel beam failure enclosing the opening. this method provides acceptable results in construction practices, but it is overly conservative. furthermore, the design codes reviewed do not provide any strengthening design guidelines or even strengthening recommendations. in construction practices the load part resisted by the strengthening structure is evaluate following simple engineering judgment, experimental and numerical research is needed to quantify correctly the load resisted by the strengthening components and by the existing wall. opening length opening heigth lintel beam column column opening heigth opening length column column a) opening design portal frame model b) opening design column model fig. 1. opening design models a) opening design portal frame model b) opening design column model 67 journal of sustainable architecture and civil engineering 2020/1/26 the opening. this method provides acceptable results in construction practices, but it is overly conservative. furthermore, the design codes reviewed do not provide any strengthening design guidelines or even strengthening recommendations. in construction practices the load part resisted by the strengthening structure is evaluate following simple engineering judgment, experimental and numerical research is needed to quantify correctly the load resisted by the strengthening components and by the existing wall. the strengthening openings technique introduction several practices techniques exist to strengthen openings in concrete or masonry walls, as textile reinforced mortar, bonded steel plates, externally bonded fiber reinforced polymers, thickness enlargement or concrete beams, (todut et al., 2015), (triantafillou and papanicolaou, 2006), (li and lim, 2010). in this technical note, a technique based in the introduction of steel beams and steel portal frames is described. two possibilities can be considered, in the first one, the steel structure is positioned laterally on both side of the existing wall and in the second possibility the structure axis is align with the wall longitudinal axis. for both solutions columns can be added at the beam ends, defining a steel portal frame which strengthens at the same time the existing adjacent walls. lateral steel beam strengthening this technique consists in positioning u channel beams on both side of the existing wall as represented in fig. 2. fig. 2-a) is relative to a concrete wall and in fig. 2-b) is relative to a masonry wall. on both cases the steel beams are located precisely bellow the existing floor, nevertheless, when a lintel is present, they can be applied at any level along the lintel height. fig. 2 lateral steel beams strengthening a) concrete wall b) masonry wall 3. the strengthening openings technique 3.1 introduction several practices techniques exist to strengthen openings in concrete or masonry walls, as textile reinforced mortar, bonded steel plates, externally bonded fiber reinforced polymers, thickness enlargement or concrete beams, (todut et al., 2015), (triantafillou and papanicolaou, 2006), (li and lim, 2010). in this technical note, a technique based in the introduction of steel beams and steel portal frames is described. two possibilities can be considered, in the first one, the steel structure is positioned laterally on both side of the existing wall and in the second possibility the structure axis is align with the wall longitudinal axis. for both solutions columns can be added at the beam ends, defining a steel portal frame which strengthens at the same time the existing adjacent walls. 3.2.1lateral steel beam strengthening this technique consists in positioning u channel beams on both side of the existing wall as represented in fig. 2. fig. 2-a) is relative to a concrete wall and in fig. 2-b) is relative to a masonry wall. on both cases the steel beams are located precisely bellow the existing floor, nevertheless, when a lintel is present, they can be applied at any level along the lintel height. a) concrete wall b) masonry wall fig. 2. lateral steel beams strengthening this solution can be applied for different materials and for different wall thicknesses, the concrete wall in fig. 2-a) is 18 cm thick and the masonry wall in fig. 2-b) is 50 cm thick. in fig. 2-a) the strengthening beam is loaded with the upper floor and with the lintel existing along the opening, the bearing load is transmitted to the adjacent wall thought steel columns defining a portal frame. for the masonry wall, fig. 2-b), the load is transmitted directly to the adjacent walls. the steel beams on both sides of the masonry wall are connected together with lnp channels profiles beam, fig. 3a), and the connection between the steel beams and the masonry wall is materialized through adhesive anchor threaded rods, fig. 3-b). a) transversal connection b) load bearing length and connection 3. the strengthening openings technique 3.1 introduction several practices techniques exist to strengthen openings in concrete or masonry walls, as textile reinforced mortar, bonded steel plates, externally bonded fiber reinforced polymers, thickness enlargement or concrete beams, (todut et al., 2015), (triantafillou and papanicolaou, 2006), (li and lim, 2010). in this technical note, a technique based in the introduction of steel beams and steel portal frames is described. two possibilities can be considered, in the first one, the steel structure is positioned laterally on both side of the existing wall and in the second possibility the structure axis is align with the wall longitudinal axis. for both solutions columns can be added at the beam ends, defining a steel portal frame which strengthens at the same time the existing adjacent walls. 3.2.1lateral steel beam strengthening this technique consists in positioning u channel beams on both side of the existing wall as represented in fig. 2. fig. 2-a) is relative to a concrete wall and in fig. 2-b) is relative to a masonry wall. on both cases the steel beams are located precisely bellow the existing floor, nevertheless, when a lintel is present, they can be applied at any level along the lintel height. a) concrete wall b) masonry wall fig. 2. lateral steel beams strengthening this solution can be applied for different materials and for different wall thicknesses, the concrete wall in fig. 2-a) is 18 cm thick and the masonry wall in fig. 2-b) is 50 cm thick. in fig. 2-a) the strengthening beam is loaded with the upper floor and with the lintel existing along the opening, the bearing load is transmitted to the adjacent wall thought steel columns defining a portal frame. for the masonry wall, fig. 2-b), the load is transmitted directly to the adjacent walls. the steel beams on both sides of the masonry wall are connected together with lnp channels profiles beam, fig. 3a), and the connection between the steel beams and the masonry wall is materialized through adhesive anchor threaded rods, fig. 3-b). a) transversal connection b) load bearing length and connection this solution can be applied for different materials and for different wall thicknesses, the concrete wall in fig. 2-a) is 18 cm thick and the masonry wall in fig. 2-b) is 50 cm thick. in fig. 2-a) the strengthening beam is loaded with the upper floor and with the lintel existing along the opening, the bearing load is transmitted to the adjacent wall thought steel columns defining a portal frame. for the masonry wall, fig. 2-b), the load is transmitted directly to the adjacent walls. the steel beams on both sides of the masonry wall are connected together with lnp channels profiles beam, fig. 3-a), and the connection between the steel beams and the masonry wall is materialized through adhesive anchor threaded rods, fig. 3-b). fig. 4 represents a construction drawing relative to an opening strengthening performed in a concrete wall located in a ski resort hotel located in savoie department in france. the opening is 3.00 meters long and the concrete wall is 18 cm thick. before the opening is sawed, two u channel beams constituted with unp240 profiles with a full length of 360 cm, drilled before, are positioned against the concrete wall, 19 hilti concrete wedge anchors hsa m12, 115 mm long, are bored into the wall journal of sustainable architecture and civil engineering 2020/1/26 68 through the profiles elongated holes, fig. 4-b). the distance between connectors is approximately 50 cm. at beam ends and in each wall face, two wedge anchors are bored into the wall. four 6 mm thick steel plate web stiffeners are welded along each bearing length, one on each side of the web, to avoid premature flange buckling and web crushing. the design load, corresponding to one floor, is constituted with a distributed dead load equal to 60 kn/m x 1.35 and a distributed live load equal to 18 kn/m x 1.5. the design bending moment is equal to msd =108 x 3.3 2/8 = 147 kn/m < mrd = 84 kn/m x 2 corresponding to the resistant bending moment of two upn 240. fig. 5 is relative to a construction solution similar to the previous one, but now applied to a masonry wall. this solution was applied in a haussmann building located in paris. the opening length is 340 centimeters long. two unp 300 profiles are positioned against in each side of the wall and just below the upper floor and then the existing wall is sawed along the total height. lnp metallic profiles are welded transversally to the longitudinal profiles to avoid torsion effects in each profile, fig. 5-a). at the bearings and since for masonry wall the bearing stress is limited to 700-2000 kn/m2, heb profiles are are introduced along the thickness wall to spread the beams vertical reaction along the wall masonry, fig. 5-b), avoiding the high stresses around the beam ends has m16 anchor threaded rods. the design load, corresponding to three floors, is constituted with a distributed dead load equal to 72 kn/m x 1.35 and a distributed live load equal to 30 kn/m x 1.5. the design bending moment is equal to msd = 142 x 3.7 2/8 = 243 kn/m < mrd = 148 kn/m x 2 corresponding to the resistant bending moment of two upn 300. a) transversal connection b) load bearing length and connection fig. 3 connections 3. the strengthening openings technique 3.1 introduction several practices techniques exist to strengthen openings in concrete or masonry walls, as textile reinforced mortar, bonded steel plates, externally bonded fiber reinforced polymers, thickness enlargement or concrete beams, (todut et al., 2015), (triantafillou and papanicolaou, 2006), (li and lim, 2010). in this technical note, a technique based in the introduction of steel beams and steel portal frames is described. two possibilities can be considered, in the first one, the steel structure is positioned laterally on both side of the existing wall and in the second possibility the structure axis is align with the wall longitudinal axis. for both solutions columns can be added at the beam ends, defining a steel portal frame which strengthens at the same time the existing adjacent walls. 3.2.1lateral steel beam strengthening this technique consists in positioning u channel beams on both side of the existing wall as represented in fig. 2. fig. 2-a) is relative to a concrete wall and in fig. 2-b) is relative to a masonry wall. on both cases the steel beams are located precisely bellow the existing floor, nevertheless, when a lintel is present, they can be applied at any level along the lintel height. a) concrete wall b) masonry wall fig. 2. lateral steel beams strengthening this solution can be applied for different materials and for different wall thicknesses, the concrete wall in fig. 2-a) is 18 cm thick and the masonry wall in fig. 2-b) is 50 cm thick. in fig. 2-a) the strengthening beam is loaded with the upper floor and with the lintel existing along the opening, the bearing load is transmitted to the adjacent wall thought steel columns defining a portal frame. for the masonry wall, fig. 2-b), the load is transmitted directly to the adjacent walls. the steel beams on both sides of the masonry wall are connected together with lnp channels profiles beam, fig. 3a), and the connection between the steel beams and the masonry wall is materialized through adhesive anchor threaded rods, fig. 3-b). a) transversal connection b) load bearing length and connection 3. the strengthening openings technique 3.1 introduction several practices techniques exist to strengthen openings in concrete or masonry walls, as textile reinforced mortar, bonded steel plates, externally bonded fiber reinforced polymers, thickness enlargement or concrete beams, (todut et al., 2015), (triantafillou and papanicolaou, 2006), (li and lim, 2010). in this technical note, a technique based in the introduction of steel beams and steel portal frames is described. two possibilities can be considered, in the first one, the steel structure is positioned laterally on both side of the existing wall and in the second possibility the structure axis is align with the wall longitudinal axis. for both solutions columns can be added at the beam ends, defining a steel portal frame which strengthens at the same time the existing adjacent walls. 3.2.1lateral steel beam strengthening this technique consists in positioning u channel beams on both side of the existing wall as represented in fig. 2. fig. 2-a) is relative to a concrete wall and in fig. 2-b) is relative to a masonry wall. on both cases the steel beams are located precisely bellow the existing floor, nevertheless, when a lintel is present, they can be applied at any level along the lintel height. a) concrete wall b) masonry wall fig. 2. lateral steel beams strengthening this solution can be applied for different materials and for different wall thicknesses, the concrete wall in fig. 2-a) is 18 cm thick and the masonry wall in fig. 2-b) is 50 cm thick. in fig. 2-a) the strengthening beam is loaded with the upper floor and with the lintel existing along the opening, the bearing load is transmitted to the adjacent wall thought steel columns defining a portal frame. for the masonry wall, fig. 2-b), the load is transmitted directly to the adjacent walls. the steel beams on both sides of the masonry wall are connected together with lnp channels profiles beam, fig. 3a), and the connection between the steel beams and the masonry wall is materialized through adhesive anchor threaded rods, fig. 3-b). a) transversal connection b) load bearing length and connection a) elevation view b) section a-a fig. 4 concrete wall opening strengthening fig. 3. connections fig. 4 represents a construction drawing relative to an opening strengthening performed in a concrete wall located in a ski resort hotel located in savoie department in france. the opening is 3.00 meters long and the concrete wall is 18 cm thick. before the opening is sawed, two u channel beams constituted with unp240 profiles with a full length of 360 cm, drilled before, are positioned against the concrete wall, 19 hilti concrete wedge anchors hsa m12, 115 mm long, are bored into the wall through the profiles elongated holes, fig. 4-b). the distance between connectors is approximately 50 cm. at beam ends and in each wall face, two wedge anchors are bored into the wall. four 6 mm thick steel plate web stiffeners are welded along each bearing length, one on each side of the web, to avoid premature flange buckling and web crushing. the design load, corresponding to one floor, is constituted with a distributed dead load equal to 60 kn/m x 1.35 and a distributed live load equal to 18 kn/m x 1.5. the design bending moment is equal to msd =108 x 3.32/8 = 147 kn/m < mrd = 84 kn/m x 2 corresponding to the resistant bending moment of two upn 240. unp240 elevation hsa m12x115 10+9 wedge anchor 19 elongated holes ø14x28 300 cm 30 cm +-50 cm 210 cm 30 cm a a unp240 elevation hsa m12x115 10+9 wedge anchor 19 elongated holes ø14x28 300 cm 30 cm +-50 cm 210 cm 30 cm a a a-a unp240 unp240 hsa m12x115 19 wedge anchor stiffener 18 cm a) elevation view b) section a-a fig. 4. concrete wall opening strengthening fig. 5 is relative to a construction solution similar to the previous one, but now applied to a masonry wall. this solution was applied in a haussmann building located in paris. the opening length is 340 centimeters long. two unp 300 profiles are positioned against in each side of the wall and just below the upper floor and then the existing wall is sawed along the total height. lnp metallic profiles are welded transversally to the longitudinal profiles to avoid torsion effects in each profile, fig. 5-a). elevation unp300 heb240 heb240 iao slab 340 cm 3 lnp60x60x10 matting 300 cm a a 30 cm30 cm 4 anchor rods has m16 8.8 4 elongated holes ø18x36 adhesive anchors hit-hy-200 heb240 unp300 matting 50 cm lnp 60x60x10 a) elevation view b) section a-a fig. 5. masonry wall opening strengthening at the bearings and since for masonry wall the bearing stress is limited to 700-2000 kn/m2, heb fig. 3. connections fig. 4 represents a construction drawing relative to an opening strengthening performed in a concrete wall located in a ski resort hotel located in savoie department in france. the opening is 3.00 meters long and the concrete wall is 18 cm thick. before the opening is sawed, two u channel beams constituted with unp240 profiles with a full length of 360 cm, drilled before, are positioned against the concrete wall, 19 hilti concrete wedge anchors hsa m12, 115 mm long, are bored into the wall through the profiles elongated holes, fig. 4-b). the distance between connectors is approximately 50 cm. at beam ends and in each wall face, two wedge anchors are bored into the wall. four 6 mm thick steel plate web stiffeners are welded along each bearing length, one on each side of the web, to avoid premature flange buckling and web crushing. the design load, corresponding to one floor, is constituted with a distributed dead load equal to 60 kn/m x 1.35 and a distributed live load equal to 18 kn/m x 1.5. the design bending moment is equal to msd =108 x 3.32/8 = 147 kn/m < mrd = 84 kn/m x 2 corresponding to the resistant bending moment of two upn 240. unp240 elevation hsa m12x115 10+9 wedge anchor 19 elongated holes ø14x28 300 cm 30 cm +-50 cm 210 cm 30 cm a a unp240 elevation hsa m12x115 10+9 wedge anchor 19 elongated holes ø14x28 300 cm 30 cm +-50 cm 210 cm 30 cm a a a-a unp240 unp240 hsa m12x115 19 wedge anchor stiffener 18 cm a) elevation view b) section a-a fig. 4. concrete wall opening strengthening fig. 5 is relative to a construction solution similar to the previous one, but now applied to a masonry wall. this solution was applied in a haussmann building located in paris. the opening length is 340 centimeters long. two unp 300 profiles are positioned against in each side of the wall and just below the upper floor and then the existing wall is sawed along the total height. lnp metallic profiles are welded transversally to the longitudinal profiles to avoid torsion effects in each profile, fig. 5-a). elevation unp300 heb240 heb240 iao slab 340 cm 3 lnp60x60x10 matting 300 cm a a 30 cm30 cm 4 anchor rods has m16 8.8 4 elongated holes ø18x36 adhesive anchors hit-hy-200 heb240 unp300 matting 50 cm lnp 60x60x10 a) elevation view b) section a-a fig. 5. masonry wall opening strengthening at the bearings and since for masonry wall the bearing stress is limited to 700-2000 kn/m2, heb 69 journal of sustainable architecture and civil engineering 2020/1/26 using the same technique, a 100 cm long strengthen opening located in the haute-savoie department, is represented in fig. 6-a). in that case, and as represented in fig. 6-b), beyond the two u channels beams, two columns constituted with unp 120 profiles are positioned against the wall to support the u channel beam ends, defining a portal frame. the u channel beams are linked together through 6 adhesive anchor threaded rods has m16 8.8 from hilti , fig. 6-b). each u channel column is 50 cm high, fig. 7-a) and is fixed through 3 chemical anchor rods has m16 8.8 from hilti, fig. 7-b). a) elevation view b) section a-a fig. 5 masonry wall opening strengthening fig. 3. connections fig. 4 represents a construction drawing relative to an opening strengthening performed in a concrete wall located in a ski resort hotel located in savoie department in france. the opening is 3.00 meters long and the concrete wall is 18 cm thick. before the opening is sawed, two u channel beams constituted with unp240 profiles with a full length of 360 cm, drilled before, are positioned against the concrete wall, 19 hilti concrete wedge anchors hsa m12, 115 mm long, are bored into the wall through the profiles elongated holes, fig. 4-b). the distance between connectors is approximately 50 cm. at beam ends and in each wall face, two wedge anchors are bored into the wall. four 6 mm thick steel plate web stiffeners are welded along each bearing length, one on each side of the web, to avoid premature flange buckling and web crushing. the design load, corresponding to one floor, is constituted with a distributed dead load equal to 60 kn/m x 1.35 and a distributed live load equal to 18 kn/m x 1.5. the design bending moment is equal to msd =108 x 3.32/8 = 147 kn/m < mrd = 84 kn/m x 2 corresponding to the resistant bending moment of two upn 240. unp240 elevation hsa m12x115 10+9 wedge anchor 19 elongated holes ø14x28 300 cm 30 cm +-50 cm 210 cm 30 cm a a unp240 elevation hsa m12x115 10+9 wedge anchor 19 elongated holes ø14x28 300 cm 30 cm +-50 cm 210 cm 30 cm a a a-a unp240 unp240 hsa m12x115 19 wedge anchor stiffener 18 cm a) elevation view b) section a-a fig. 4. concrete wall opening strengthening fig. 5 is relative to a construction solution similar to the previous one, but now applied to a masonry wall. this solution was applied in a haussmann building located in paris. the opening length is 340 centimeters long. two unp 300 profiles are positioned against in each side of the wall and just below the upper floor and then the existing wall is sawed along the total height. lnp metallic profiles are welded transversally to the longitudinal profiles to avoid torsion effects in each profile, fig. 5-a). elevation unp300 heb240 heb240 iao slab 340 cm 3 lnp60x60x10 matting 300 cm a a 30 cm30 cm 4 anchor rods has m16 8.8 4 elongated holes ø18x36 adhesive anchors hit-hy-200 heb240 unp300 matting 50 cm lnp 60x60x10 a) elevation view b) section a-a fig. 5. masonry wall opening strengthening at the bearings and since for masonry wall the bearing stress is limited to 700-2000 kn/m2, heb fig. 3. connections fig. 4 represents a construction drawing relative to an opening strengthening performed in a concrete wall located in a ski resort hotel located in savoie department in france. the opening is 3.00 meters long and the concrete wall is 18 cm thick. before the opening is sawed, two u channel beams constituted with unp240 profiles with a full length of 360 cm, drilled before, are positioned against the concrete wall, 19 hilti concrete wedge anchors hsa m12, 115 mm long, are bored into the wall through the profiles elongated holes, fig. 4-b). the distance between connectors is approximately 50 cm. at beam ends and in each wall face, two wedge anchors are bored into the wall. four 6 mm thick steel plate web stiffeners are welded along each bearing length, one on each side of the web, to avoid premature flange buckling and web crushing. the design load, corresponding to one floor, is constituted with a distributed dead load equal to 60 kn/m x 1.35 and a distributed live load equal to 18 kn/m x 1.5. the design bending moment is equal to msd =108 x 3.32/8 = 147 kn/m < mrd = 84 kn/m x 2 corresponding to the resistant bending moment of two upn 240. unp240 elevation hsa m12x115 10+9 wedge anchor 19 elongated holes ø14x28 300 cm 30 cm +-50 cm 210 cm 30 cm a a unp240 elevation hsa m12x115 10+9 wedge anchor 19 elongated holes ø14x28 300 cm 30 cm +-50 cm 210 cm 30 cm a a a-a unp240 unp240 hsa m12x115 19 wedge anchor stiffener 18 cm a) elevation view b) section a-a fig. 4. concrete wall opening strengthening fig. 5 is relative to a construction solution similar to the previous one, but now applied to a masonry wall. this solution was applied in a haussmann building located in paris. the opening length is 340 centimeters long. two unp 300 profiles are positioned against in each side of the wall and just below the upper floor and then the existing wall is sawed along the total height. lnp metallic profiles are welded transversally to the longitudinal profiles to avoid torsion effects in each profile, fig. 5-a). elevation unp300 heb240 heb240 iao slab 340 cm 3 lnp60x60x10 matting 300 cm a a 30 cm30 cm 4 anchor rods has m16 8.8 4 elongated holes ø18x36 adhesive anchors hit-hy-200 heb240 unp300 matting 50 cm lnp 60x60x10 a) elevation view b) section a-a fig. 5. masonry wall opening strengthening at the bearings and since for masonry wall the bearing stress is limited to 700-2000 kn/m2, heb a) plan view b) elevation view a-a fig. 6 portal frame opening strengthening i fig. 7 portal frame opening strengthening ii a) elevation view b-b b) section c-c profiles are are introduced along the thickness wall to spread the beams vertical reaction along the wall masonry, fig. 5-b), avoiding the high stresses around the beam ends has m16 anchor threaded rods. the design load, corresponding to three floors, is constituted with a distributed dead load equal to 72 kn/m x 1.35 and a distributed live load equal to 30 kn/m x 1.5. the design bending moment is equal to msd = 142 x 3.72/8 = 243 kn/m < mrd = 148 kn/m x 2 corresponding to the resistant bending moment of two upn 300. using the same technique, a 100 cm long strengthen opening located in the haute-savoie department, is represented in fig. 6-a). in that case, and as represented in fig. 6-b), beyond the two u channels beams, two columns constituted with unp 120 profiles are positioned against the wall to support the u channel beam ends, defining a portal frame. the u channel beams are linked together through 6 adhesive anchor threaded rods has m16 8.8 from hilti , fig. 6-b). bay unp140 unp140 unp120 unp120 unp120 c c a a b b concrete wall existing 100 cm20 cm 20 cm unp140 unp120 elevation a-a anchor rods has m16 8.8 4x2 web stiffener 6 mm 6 elongated holes ø18x36 3x2 adhesive anchors hit-hy-200 unp120 a) plan view b) elevation view a-a fig. 6. portal frame opening strengthening i each u channel column is 50 cm high, fig. 7-a) and is fixed through 3 chemical anchor rods has m16 8.8 from hilti, fig. 7-b). unp120 bay unp140 elevation b-b 6 anchor rods has m16 8.8 6 elongated holes ø18x36 adhesive anchors hit-hy-200 210 cm 100 cm unp120 unp140 unp140 m16 8.8 chemical anchor has rods has m16 8.8 3x2 6 chemical anchor stiffener web stiffener web 50 cm 6 mm6 mm a) elevation view b-b b) section c-c fig. 7. portal frame opening strengthening ii this solution allows to diffuse the beam reaction along the wall height, avoiding high stresses around the beam ends chemical anchor rods has m16. 3.2.2 align steel beam strengthening in this technique the opening is strengthened with a beam whose axis is aligned with the existing wall axis. in fig. 8, two bolted steel channels running side by side along the opening and supported by bays created in the adjacent walls are represented. profiles are are introduced along the thickness wall to spread the beams vertical reaction along the wall masonry, fig. 5-b), avoiding the high stresses around the beam ends has m16 anchor threaded rods. the design load, corresponding to three floors, is constituted with a distributed dead load equal to 72 kn/m x 1.35 and a distributed live load equal to 30 kn/m x 1.5. the design bending moment is equal to msd = 142 x 3.72/8 = 243 kn/m < mrd = 148 kn/m x 2 corresponding to the resistant bending moment of two upn 300. using the same technique, a 100 cm long strengthen opening located in the haute-savoie department, is represented in fig. 6-a). in that case, and as represented in fig. 6-b), beyond the two u channels beams, two columns constituted with unp 120 profiles are positioned against the wall to support the u channel beam ends, defining a portal frame. the u channel beams are linked together through 6 adhesive anchor threaded rods has m16 8.8 from hilti , fig. 6-b). bay unp140 unp140 unp120 unp120 unp120 c c a a b b concrete wall existing 100 cm20 cm 20 cm unp140 unp120 elevation a-a anchor rods has m16 8.8 4x2 web stiffener 6 mm 6 elongated holes ø18x36 3x2 adhesive anchors hit-hy-200 unp120 a) plan view b) elevation view a-a fig. 6. portal frame opening strengthening i each u channel column is 50 cm high, fig. 7-a) and is fixed through 3 chemical anchor rods has m16 8.8 from hilti, fig. 7-b). unp120 bay unp140 elevation b-b 6 anchor rods has m16 8.8 6 elongated holes ø18x36 adhesive anchors hit-hy-200 210 cm 100 cm unp120 unp140 unp140 m16 8.8 chemical anchor has rods has m16 8.8 3x2 6 chemical anchor stiffener web stiffener web 50 cm 6 mm6 mm a) elevation view b-b b) section c-c fig. 7. portal frame opening strengthening ii this solution allows to diffuse the beam reaction along the wall height, avoiding high stresses around the beam ends chemical anchor rods has m16. 3.2.2 align steel beam strengthening in this technique the opening is strengthened with a beam whose axis is aligned with the existing wall axis. in fig. 8, two bolted steel channels running side by side along the opening and supported by bays created in the adjacent walls are represented. profiles are are introduced along the thickness wall to spread the beams vertical reaction along the wall masonry, fig. 5-b), avoiding the high stresses around the beam ends has m16 anchor threaded rods. the design load, corresponding to three floors, is constituted with a distributed dead load equal to 72 kn/m x 1.35 and a distributed live load equal to 30 kn/m x 1.5. the design bending moment is equal to msd = 142 x 3.72/8 = 243 kn/m < mrd = 148 kn/m x 2 corresponding to the resistant bending moment of two upn 300. using the same technique, a 100 cm long strengthen opening located in the haute-savoie department, is represented in fig. 6-a). in that case, and as represented in fig. 6-b), beyond the two u channels beams, two columns constituted with unp 120 profiles are positioned against the wall to support the u channel beam ends, defining a portal frame. the u channel beams are linked together through 6 adhesive anchor threaded rods has m16 8.8 from hilti , fig. 6-b). bay unp140 unp140 unp120 unp120 unp120 c c a a b b concrete wall existing 100 cm20 cm 20 cm unp140 unp120 elevation a-a anchor rods has m16 8.8 4x2 web stiffener 6 mm 6 elongated holes ø18x36 3x2 adhesive anchors hit-hy-200 unp120 a) plan view b) elevation view a-a fig. 6. portal frame opening strengthening i each u channel column is 50 cm high, fig. 7-a) and is fixed through 3 chemical anchor rods has m16 8.8 from hilti, fig. 7-b). unp120 bay unp140 elevation b-b 6 anchor rods has m16 8.8 6 elongated holes ø18x36 adhesive anchors hit-hy-200 210 cm 100 cm unp120 unp140 unp140 m16 8.8 chemical anchor has rods has m16 8.8 3x2 6 chemical anchor stiffener web stiffener web 50 cm 6 mm6 mm a) elevation view b-b b) section c-c fig. 7. portal frame opening strengthening ii this solution allows to diffuse the beam reaction along the wall height, avoiding high stresses around the beam ends chemical anchor rods has m16. 3.2.2 align steel beam strengthening in this technique the opening is strengthened with a beam whose axis is aligned with the existing wall axis. in fig. 8, two bolted steel channels running side by side along the opening and supported by bays created in the adjacent walls are represented. profiles are are introduced along the thickness wall to spread the beams vertical reaction along the wall masonry, fig. 5-b), avoiding the high stresses around the beam ends has m16 anchor threaded rods. the design load, corresponding to three floors, is constituted with a distributed dead load equal to 72 kn/m x 1.35 and a distributed live load equal to 30 kn/m x 1.5. the design bending moment is equal to msd = 142 x 3.72/8 = 243 kn/m < mrd = 148 kn/m x 2 corresponding to the resistant bending moment of two upn 300. using the same technique, a 100 cm long strengthen opening located in the haute-savoie department, is represented in fig. 6-a). in that case, and as represented in fig. 6-b), beyond the two u channels beams, two columns constituted with unp 120 profiles are positioned against the wall to support the u channel beam ends, defining a portal frame. the u channel beams are linked together through 6 adhesive anchor threaded rods has m16 8.8 from hilti , fig. 6-b). bay unp140 unp140 unp120 unp120 unp120 c c a a b b concrete wall existing 100 cm20 cm 20 cm unp140 unp120 elevation a-a anchor rods has m16 8.8 4x2 web stiffener 6 mm 6 elongated holes ø18x36 3x2 adhesive anchors hit-hy-200 unp120 a) plan view b) elevation view a-a fig. 6. portal frame opening strengthening i each u channel column is 50 cm high, fig. 7-a) and is fixed through 3 chemical anchor rods has m16 8.8 from hilti, fig. 7-b). unp120 bay unp140 elevation b-b 6 anchor rods has m16 8.8 6 elongated holes ø18x36 adhesive anchors hit-hy-200 210 cm 100 cm unp120 unp140 unp140 m16 8.8 chemical anchor has rods has m16 8.8 3x2 6 chemical anchor stiffener web stiffener web 50 cm 6 mm6 mm a) elevation view b-b b) section c-c fig. 7. portal frame opening strengthening ii this solution allows to diffuse the beam reaction along the wall height, avoiding high stresses around the beam ends chemical anchor rods has m16. 3.2.2 align steel beam strengthening in this technique the opening is strengthened with a beam whose axis is aligned with the existing wall axis. in fig. 8, two bolted steel channels running side by side along the opening and supported by bays created in the adjacent walls are represented. journal of sustainable architecture and civil engineering 2020/1/26 70 this solution allows to diffuse the beam reaction along the wall height, avoiding high stresses around the beam ends chemical anchor rods has m16. align steel beam strengthening in this technique the opening is strengthened with a beam whose axis is aligned with the existing wall axis. in fig. 8, two bolted steel channels running side by side along the opening and supported by bays created in the adjacent walls are represented. fig. 8 opening strengthening fig. 9 align beam strengthening fig. 8. opening strengthening fig. 9 represents the design drawing relative to a concrete wall opening strengthening corresponding to the association of two apartments located in paris. the concrete wall is 15 cm thick, the opening is 3.40 meter long. to achieve the strengthening a specific methodology is applied. first, the opening is created cutting the wall with 1 meter long width and positioning at the same time vertical props, fig. 9-a). this operation is repeated until the entire opening is created. at the end the entire upper structure is held up by vertical props positioned along two rows located on both sides of the wall axis, as represented in fig. 9-b). secondly, all the props located along one row are removed and the first unp channel is positioned. this operation is then repeated for the second props row and the second unp channel is positioned. b b a a concrete wall existing 340 cm20 cm 20 cm bay bay concrete wall swawing vertical prop b-b unp240 vertical prop stiffener 8x1 web 6 mm a) wall cutting and vertical props positioning b) section b-b fig. 9. align beam strengthening as represented in fig. 10-a) , the two u channels are 3.80 meters long and are bolted together using 8 m12 8.8 bolts. web stiffeners 6 mm thick are introduced in the bearing length, as represented in fig. 10-b). the bearing length is 20 cm long and consists in bays created in the existing wall. elevation a-a 340 cm matting 2xunp240 50 cm 8 bolts m12 8.8 8 elongated holes ø14x28 stiffener 8x1 web 6 mm 210 cm b-b 2xunp240 matting 15 cm 8 bolts m12 8.8 stiffener 8x1 web 6 mm a) steel beam strengthening b) fig. 10. elevation view fig. 9 represents the design drawing relative to a concrete wall opening strengthening corresponding to the association of two apartments located in paris. the concrete wall is 15 cm thick, the opening is 3.40 meter long. to achieve the strengthening a specific methodology is applied. first, the opening is created cutting the wall with 1 meter long width and positioning at the same time vertical props, fig. 9-a). this operation is repeated until the entire opening is created. at the end the entire upper structure is held up by vertical props positioned along two rows located on both sides of the wall axis, as represented in fig. 9-b). secondly, all the props located along one row are removed and the first unp channel is positioned. this operation is then repeated for the second props row and the second unp channel is positioned. a) wall cutting and vertical props positioning b) section b-b fig. 8. opening strengthening fig. 9 represents the design drawing relative to a concrete wall opening strengthening corresponding to the association of two apartments located in paris. the concrete wall is 15 cm thick, the opening is 3.40 meter long. to achieve the strengthening a specific methodology is applied. first, the opening is created cutting the wall with 1 meter long width and positioning at the same time vertical props, fig. 9-a). this operation is repeated until the entire opening is created. at the end the entire upper structure is held up by vertical props positioned along two rows located on both sides of the wall axis, as represented in fig. 9-b). secondly, all the props located along one row are removed and the first unp channel is positioned. this operation is then repeated for the second props row and the second unp channel is positioned. b b a a concrete wall existing 340 cm20 cm 20 cm bay bay concrete wall swawing vertical prop b-b unp240 vertical prop stiffener 8x1 web 6 mm a) wall cutting and vertical props positioning b) section b-b fig. 9. align beam strengthening as represented in fig. 10-a) , the two u channels are 3.80 meters long and are bolted together using 8 m12 8.8 bolts. web stiffeners 6 mm thick are introduced in the bearing length, as represented in fig. 10-b). the bearing length is 20 cm long and consists in bays created in the existing wall. elevation a-a 340 cm matting 2xunp240 50 cm 8 bolts m12 8.8 8 elongated holes ø14x28 stiffener 8x1 web 6 mm 210 cm b-b 2xunp240 matting 15 cm 8 bolts m12 8.8 stiffener 8x1 web 6 mm a) steel beam strengthening b) fig. 10. elevation view fig. 8. opening strengthening fig. 9 represents the design drawing relative to a concrete wall opening strengthening corresponding to the association of two apartments located in paris. the concrete wall is 15 cm thick, the opening is 3.40 meter long. to achieve the strengthening a specific methodology is applied. first, the opening is created cutting the wall with 1 meter long width and positioning at the same time vertical props, fig. 9-a). this operation is repeated until the entire opening is created. at the end the entire upper structure is held up by vertical props positioned along two rows located on both sides of the wall axis, as represented in fig. 9-b). secondly, all the props located along one row are removed and the first unp channel is positioned. this operation is then repeated for the second props row and the second unp channel is positioned. b b a a concrete wall existing 340 cm20 cm 20 cm bay bay concrete wall swawing vertical prop b-b unp240 vertical prop stiffener 8x1 web 6 mm a) wall cutting and vertical props positioning b) section b-b fig. 9. align beam strengthening as represented in fig. 10-a) , the two u channels are 3.80 meters long and are bolted together using 8 m12 8.8 bolts. web stiffeners 6 mm thick are introduced in the bearing length, as represented in fig. 10-b). the bearing length is 20 cm long and consists in bays created in the existing wall. elevation a-a 340 cm matting 2xunp240 50 cm 8 bolts m12 8.8 8 elongated holes ø14x28 stiffener 8x1 web 6 mm 210 cm b-b 2xunp240 matting 15 cm 8 bolts m12 8.8 stiffener 8x1 web 6 mm a) steel beam strengthening b) fig. 10. elevation view as represented in fig. 10-a) , the two u channels are 3.80 meters long and are bolted together using 8 m12 8.8 bolts. web stiffeners 6 mm thick are introduced in the bearing length, as represented in fig. 10-b). the bearing length is 20 cm long and consists in bays created in the existing wall. the solution presented in fig. 11 is similar to the previous one, but complementary, vertical steel u channels are connected to the opening lateral sides, fig. 11-a), defining a steel portal frame. the columns and beams define a stiffer structure, when compared to the previous one, and at the same time they strengthen the wall opening lateral sides. the two u channels beams are bolted 71 journal of sustainable architecture and civil engineering 2020/1/26 together trough 6 bolts m12 8.8 inserted in 6 elongated holes. web stiffeners 6 mm thick are located at the u channel beam ends as represented in fig. 11-b). the constructive methodology is also similar to the previous one, but during the positioning of each u channel and before the introduction of the columns it is necessary to underpinned the beam with vertical props, as represented in fig. 11-b). the connection between the u channel and the opening lateral side is materialized trough 5 adhesive anchor threaded rods has m12, fig. 11-a) and fig. 12-a). the connection between the u channel columns and the floor is realized with a steel plates 10 mm thick and one hilty adhesive anchor rod has m10, fig. 12-b) and the connection between each column and the beam is materialized with a steel plate 10 mm thick and two bolts m12 8.8, fig. 12-c). the technique described as been used for opening lengths varying from 1.00 to 3.50 meters. grade 235 steel is used with a yielding strength of 235mpa and with an elastic modulus of 200gpa. this practice construction technique has shown good results along time, being currently a traditional opening strengthening technique. fig. 10 elevation view a) steel beam strengthening b) section b-b fig. 8. opening strengthening fig. 9 represents the design drawing relative to a concrete wall opening strengthening corresponding to the association of two apartments located in paris. the concrete wall is 15 cm thick, the opening is 3.40 meter long. to achieve the strengthening a specific methodology is applied. first, the opening is created cutting the wall with 1 meter long width and positioning at the same time vertical props, fig. 9-a). this operation is repeated until the entire opening is created. at the end the entire upper structure is held up by vertical props positioned along two rows located on both sides of the wall axis, as represented in fig. 9-b). secondly, all the props located along one row are removed and the first unp channel is positioned. this operation is then repeated for the second props row and the second unp channel is positioned. b b a a concrete wall existing 340 cm20 cm 20 cm bay bay concrete wall swawing vertical prop b-b unp240 vertical prop stiffener 8x1 web 6 mm a) wall cutting and vertical props positioning b) section b-b fig. 9. align beam strengthening as represented in fig. 10-a) , the two u channels are 3.80 meters long and are bolted together using 8 m12 8.8 bolts. web stiffeners 6 mm thick are introduced in the bearing length, as represented in fig. 10-b). the bearing length is 20 cm long and consists in bays created in the existing wall. elevation a-a 340 cm matting 2xunp240 50 cm 8 bolts m12 8.8 8 elongated holes ø14x28 stiffener 8x1 web 6 mm 210 cm b-b 2xunp240 matting 15 cm 8 bolts m12 8.8 stiffener 8x1 web 6 mm a) steel beam strengthening b) fig. 10. elevation view fig. 8. opening strengthening fig. 9 represents the design drawing relative to a concrete wall opening strengthening corresponding to the association of two apartments located in paris. the concrete wall is 15 cm thick, the opening is 3.40 meter long. to achieve the strengthening a specific methodology is applied. first, the opening is created cutting the wall with 1 meter long width and positioning at the same time vertical props, fig. 9-a). this operation is repeated until the entire opening is created. at the end the entire upper structure is held up by vertical props positioned along two rows located on both sides of the wall axis, as represented in fig. 9-b). secondly, all the props located along one row are removed and the first unp channel is positioned. this operation is then repeated for the second props row and the second unp channel is positioned. b b a a concrete wall existing 340 cm20 cm 20 cm bay bay concrete wall swawing vertical prop b-b unp240 vertical prop stiffener 8x1 web 6 mm a) wall cutting and vertical props positioning b) section b-b fig. 9. align beam strengthening as represented in fig. 10-a) , the two u channels are 3.80 meters long and are bolted together using 8 m12 8.8 bolts. web stiffeners 6 mm thick are introduced in the bearing length, as represented in fig. 10-b). the bearing length is 20 cm long and consists in bays created in the existing wall. elevation a-a 340 cm matting 2xunp240 50 cm 8 bolts m12 8.8 8 elongated holes ø14x28 stiffener 8x1 web 6 mm 210 cm b-b 2xunp240 matting 15 cm 8 bolts m12 8.8 stiffener 8x1 web 6 mm a) steel beam strengthening b) fig. 10. elevation view fig. 11 steel frame opening strengthening a) steel frame b) opening underpinning the solution presented in fig. 11 is similar to the previous one, but complementary, vertical steel u channels are connected to the opening lateral sides, fig. 11-a), defining a steel portal frame. the columns and beams define a stiffer structure, when compared to the previous one, and at the same time they strengthen the wall opening lateral sides. the two u channels beams are bolted together trough 6 bolts m12 8.8 inserted in 6 elongated holes. web stiffeners 6 mm thick are located at the u channel beam ends as represented in fig. 11-b). the constructive methodology is also similar to the previous one, but during the positioning of each u channel and before the introduction of the columns it is necessary to underpinned the beam with vertical props, as represented in fig. 11-b). elevation 350 cm matting 2xunp300 50 cm 6 bolts m12 8.8 6 elongated holes ø14x28 unp160 unp160 2x1 steel plate 2x1 steel plate 100x200x10 100x160x10 5x2 anchor rods has m12 stiffener 4x1 web 6 mm 210 cm bb c c a a unp300 vertical prop vertical prop stiffener 4x1 web 6 mm a) steel frame b) opening underpinning fig. 11. steel frame opening strengthening the connection between the u channel and the opening lateral side is materialized trough 5 adhesive anchor threaded rods has m12, fig. 11-a) and fig. 12-a). the connection between the u channel columns and the floor is realized with a steel plates 10 mm thick and one hilty adhesive anchor rod has m10, fig. 12-b) and the connection between each column and the beam is materialized with a steel plate 10 mm thick and two bolts m12 8.8, fig. 12-c). a-a 2xunp300 matting 6 bolts m12 8.8 stiffener 4x1 web 6 mm 5x2 anchor rods has m12 2x1 steel plate 100x160x10 unp160 cc d d 2x 2x1 anchor rod has m10 2xunp160 2x1 steel plate 100x160x10 holes ø12 b-b b) column/floor connection 2 x u n p 16 0 2x1 steel plate 100x200x10 2x2 bolts m12 8.8 holes ø14 c-c a) column connection c) column/beam connection fig. 12 – connection detailing the technique described as been used for opening lengths varying from 1.00 to 3.50 meters. grade the solution presented in fig. 11 is similar to the previous one, but complementary, vertical steel u channels are connected to the opening lateral sides, fig. 11-a), defining a steel portal frame. the columns and beams define a stiffer structure, when compared to the previous one, and at the same time they strengthen the wall opening lateral sides. the two u channels beams are bolted together trough 6 bolts m12 8.8 inserted in 6 elongated holes. web stiffeners 6 mm thick are located at the u channel beam ends as represented in fig. 11-b). the constructive methodology is also similar to the previous one, but during the positioning of each u channel and before the introduction of the columns it is necessary to underpinned the beam with vertical props, as represented in fig. 11-b). elevation 350 cm matting 2xunp300 50 cm 6 bolts m12 8.8 6 elongated holes ø14x28 unp160 unp160 2x1 steel plate 2x1 steel plate 100x200x10 100x160x10 5x2 anchor rods has m12 stiffener 4x1 web 6 mm 210 cm bb c c a a unp300 vertical prop vertical prop stiffener 4x1 web 6 mm a) steel frame b) opening underpinning fig. 11. steel frame opening strengthening the connection between the u channel and the opening lateral side is materialized trough 5 adhesive anchor threaded rods has m12, fig. 11-a) and fig. 12-a). the connection between the u channel columns and the floor is realized with a steel plates 10 mm thick and one hilty adhesive anchor rod has m10, fig. 12-b) and the connection between each column and the beam is materialized with a steel plate 10 mm thick and two bolts m12 8.8, fig. 12-c). a-a 2xunp300 matting 6 bolts m12 8.8 stiffener 4x1 web 6 mm 5x2 anchor rods has m12 2x1 steel plate 100x160x10 unp160 cc d d 2x 2x1 anchor rod has m10 2xunp160 2x1 steel plate 100x160x10 holes ø12 b-b b) column/floor connection 2 x u n p 16 0 2x1 steel plate 100x200x10 2x2 bolts m12 8.8 holes ø14 c-c a) column connection c) column/beam connection fig. 12 – connection detailing the technique described as been used for opening lengths varying from 1.00 to 3.50 meters. grade journal of sustainable architecture and civil engineering 2020/1/26 72 the current normative documents as eurocode, beyond others, do not provide any guidelines regarding wall opening strengthening techniques or even the design of openings created in existing walls. in this paper a current practical strengthening technique currently applied in paris haussmann buildings and in savoie and haute-savoie departments ski resort hotels that uses steel profiles to strengthen vertically loaded walls with openings is presented and described and construction design drawings are delivered. this engineering practice presents acceptable results, preserving the carrying capacity of the walls and compensating the wall stiffness reduction being recommended to strengthen walls with openings. currently, in design practice, a simplified method which consists in dividing the wall with openings into isolated columns connected by a beam is adopted, resulting in a slight overdesign for the structural elements, thus providing excessive safety. nevertheless, the degree to which the upgrade system and the existing structural elements share the loads need to be quantify, thus experimental and numerical research should be realized in order to validate accurate and safe design procedures regarding this strengthening technique and to support the development of normative strengthening guidelines. fig. 12 connection detailing a) column connection c) column/beam connection the solution presented in fig. 11 is similar to the previous one, but complementary, vertical steel u channels are connected to the opening lateral sides, fig. 11-a), defining a steel portal frame. the columns and beams define a stiffer structure, when compared to the previous one, and at the same time they strengthen the wall opening lateral sides. the two u channels beams are bolted together trough 6 bolts m12 8.8 inserted in 6 elongated holes. web stiffeners 6 mm thick are located at the u channel beam ends as represented in fig. 11-b). the constructive methodology is also similar to the previous one, but during the positioning of each u channel and before the introduction of the columns it is necessary to underpinned the beam with vertical props, as represented in fig. 11-b). elevation 350 cm matting 2xunp300 50 cm 6 bolts m12 8.8 6 elongated holes ø14x28 unp160 unp160 2x1 steel plate 2x1 steel plate 100x200x10 100x160x10 5x2 anchor rods has m12 stiffener 4x1 web 6 mm 210 cm bb c c a a unp300 vertical prop vertical prop stiffener 4x1 web 6 mm a) steel frame b) opening underpinning fig. 11. steel frame opening strengthening the connection between the u channel and the opening lateral side is materialized trough 5 adhesive anchor threaded rods has m12, fig. 11-a) and fig. 12-a). the connection between the u channel columns and the floor is realized with a steel plates 10 mm thick and one hilty adhesive anchor rod has m10, fig. 12-b) and the connection between each column and the beam is materialized with a steel plate 10 mm thick and two bolts m12 8.8, fig. 12-c). a-a 2xunp300 matting 6 bolts m12 8.8 stiffener 4x1 web 6 mm 5x2 anchor rods has m12 2x1 steel plate 100x160x10 unp160 cc d d 2x 2x1 anchor rod has m10 2xunp160 2x1 steel plate 100x160x10 holes ø12 b-b b) column/floor connection 2 x u n p 16 0 2x1 steel plate 100x200x10 2x2 bolts m12 8.8 holes ø14 c-c a) column connection c) column/beam connection fig. 12 – connection detailing the technique described as been used for opening lengths varying from 1.00 to 3.50 meters. grade the solution presented in fig. 11 is similar to the previous one, but complementary, vertical steel u channels are connected to the opening lateral sides, fig. 11-a), defining a steel portal frame. the columns and beams define a stiffer structure, when compared to the previous one, and at the same time they strengthen the wall opening lateral sides. the two u channels beams are bolted together trough 6 bolts m12 8.8 inserted in 6 elongated holes. web stiffeners 6 mm thick are located at the u channel beam ends as represented in fig. 11-b). the constructive methodology is also similar to the previous one, but during the positioning of each u channel and before the introduction of the columns it is necessary to underpinned the beam with vertical props, as represented in fig. 11-b). elevation 350 cm matting 2xunp300 50 cm 6 bolts m12 8.8 6 elongated holes ø14x28 unp160 unp160 2x1 steel plate 2x1 steel plate 100x200x10 100x160x10 5x2 anchor rods has m12 stiffener 4x1 web 6 mm 210 cm bb c c a a unp300 vertical prop vertical prop stiffener 4x1 web 6 mm a) steel frame b) opening underpinning fig. 11. steel frame opening strengthening the connection between the u channel and the opening lateral side is materialized trough 5 adhesive anchor threaded rods has m12, fig. 11-a) and fig. 12-a). the connection between the u channel columns and the floor is realized with a steel plates 10 mm thick and one hilty adhesive anchor rod has m10, fig. 12-b) and the connection between each column and the beam is materialized with a steel plate 10 mm thick and two bolts m12 8.8, fig. 12-c). a-a 2xunp300 matting 6 bolts m12 8.8 stiffener 4x1 web 6 mm 5x2 anchor rods has m12 2x1 steel plate 100x160x10 unp160 cc d d 2x 2x1 anchor rod has m10 2xunp160 2x1 steel plate 100x160x10 holes ø12 b-b b) column/floor connection 2 x u n p 16 0 2x1 steel plate 100x200x10 2x2 bolts m12 8.8 holes ø14 c-c a) column connection c) column/beam connection fig. 12 – connection detailing the technique described as been used for opening lengths varying from 1.00 to 3.50 meters. grade the solution presented in fig. 11 is similar to the previous one, but complementary, vertical steel u channels are connected to the opening lateral sides, fig. 11-a), defining a steel portal frame. the columns and beams define a stiffer structure, when compared to the previous one, and at the same time they strengthen the wall opening lateral sides. the two u channels beams are bolted together trough 6 bolts m12 8.8 inserted in 6 elongated holes. web stiffeners 6 mm thick are located at the u channel beam ends as represented in fig. 11-b). the constructive methodology is also similar to the previous one, but during the positioning of each u channel and before the introduction of the columns it is necessary to underpinned the beam with vertical props, as represented in fig. 11-b). elevation 350 cm matting 2xunp300 50 cm 6 bolts m12 8.8 6 elongated holes ø14x28 unp160 unp160 2x1 steel plate 2x1 steel plate 100x200x10 100x160x10 5x2 anchor rods has m12 stiffener 4x1 web 6 mm 210 cm bb c c a a unp300 vertical prop vertical prop stiffener 4x1 web 6 mm a) steel frame b) opening underpinning fig. 11. steel frame opening strengthening the connection between the u channel and the opening lateral side is materialized trough 5 adhesive anchor threaded rods has m12, fig. 11-a) and fig. 12-a). the connection between the u channel columns and the floor is realized with a steel plates 10 mm thick and one hilty adhesive anchor rod has m10, fig. 12-b) and the connection between each column and the beam is materialized with a steel plate 10 mm thick and two bolts m12 8.8, fig. 12-c). a-a 2xunp300 matting 6 bolts m12 8.8 stiffener 4x1 web 6 mm 5x2 anchor rods has m12 2x1 steel plate 100x160x10 unp160 cc d d 2x 2x1 anchor rod has m10 2xunp160 2x1 steel plate 100x160x10 holes ø12 b-b b) column/floor connection 2 x u n p 16 0 2x1 steel plate 100x200x10 2x2 bolts m12 8.8 holes ø14 c-c a) column connection c) column/beam connection fig. 12 – connection detailing the technique described as been used for opening lengths varying from 1.00 to 3.50 meters. grade b) column/floor connection conclusions references albert, m.l., elwi, a.e.. and cheng, r.j..j. (2001) „strengthening of unreinforced masonry walls using frps.“ j. compos. constr., 5(2), 76-84. https:// doi.org/10.1061/(asce)1090-0268(2001)5:2(76) american concrete institute (2008). “guide for the design and construction of externally bonded frp systems for strengthening concrete structures.” aci 440.2r-08, farmington hills. american concrete institute (2011). “building code requirements for structural concrete and commentary.” aci318-11, farmington hills m.i. australia standards (2009). “concrete structures.” as3600, sydney, australia. canadian standards association (2004). “design of concrete structures.” can/csa-a23.3, mississauga, ontario. cardoso, r., paiva, a., pinto, j., lanzinha, j. c. (2018) “structural and material characterization of a haussmann building.” urbanism. architecture. constructions, 9(4), 347-356. cardoso, r., paiva, a., pinto, j., lanzinha, j. c. (2019) “structural and material characterization of a haushttps://doi.org/10.1061/(asce)1090-0268(2001)5:2(76) https://doi.org/10.1061/(asce)1090-0268(2001)5:2(76) 73 journal of sustainable architecture and civil engineering 2020/1/26 smann building complex at la madeleine, paris. the first step before sustainable rehabilitation and strengthening.” journal wseas transactions on environment and development. volume 15, art. #2, 14-21 cardoso, r. (2018-a) “paris haussmann building underpinning. a study case.” acta technica napocensis: civil engineering & architecture, 61(2), 40-49. cardoso, r. (2018-b) „haussmann structural floors repairs and strengthening techniques.“ ktu journal of sustainable architecture and civil engineering, 23(2),16-24. https://doi.org/10.5755/j01. sace.23.2.21426 delatte, n. (2009). failure, distress and repair of concrete structures, woodhead publishing, cambridge, uk. https://doi.org/10.1533/9781845697037 engel, p. general rehabilitation techniques using steel. http://www.constructalia.com/english/renovation_with_steel/ii_general_rehabilitation_techniques_using_steel#.vmpsnp6g9wg > (accessed 31.01.19) european committee for standardization (2004). “design of concrete structures part 1-1: general rules and rules for buildings.” eurocode 2 en19921-1, brussels. european committee for standardization (2005). “design of masonry structures part 1.1 general rules for reinforced and unreinforced masonry structures.” eurocode 6 en 1996-1-1, brussels. fragomeni, s., mendis, p. (1997). „instability analysis of normaland high-strength reinforced-concrete walls.“ j. struct. eng., 123(5), doi:10.1061/ (asce)0733-9445(1997)123:5(680). https://doi. org/10.1061/(asce)0733-9445(1997)123:5(680) li, b., lim, c. (2010). „tests on seismically damaged reinforced concrete structural walls repaired using fiber-reinforced polymers.“ j. compos. constr., 14(5), 597-608. https://doi.org/10.1061/(asce) cc.1943-5614.0000110 mohammed, b., ean, l.w., malek, m.a. (2013). „oneway rc wall panels with openings strengthened with cfrp.“ constr. build. mater., 40: 575-83. https://doi. org/10.1016/j.conbuildmat.2012.11.080 popescu, cosmin, (2015) “frp strengthening of concrete walls with openings.” doctoral thesis, luleå university of technology. popescu, c., sas, g., blanksvärd, t., täljsten, b., (2015). „concrete walls weakened by openings as compression members: a review.“ engineering structures, 89, 172-190. https://doi.org/10.1016/j. engstruct.2015.02.006 saheb, s.m., desayi, p. (1990). „ultimate strength of rc wall panels with openings.“ j. struct. https://doi. org/10.1061/(asce)0733-9445(1990)116:6(1565) eng. asce ,116(4), 1565-78. seddon, a.e. (1956). “the strength of concrete walls under axial and eccentric loads.” symposium on the strength of concrete structures, andrew rp, editor, cement and concrete association, london, uk, 445-486. todut, c., dan, d., stoian, v. (2015). „numerical and experimental investigation on seismically damaged reinforced concrete wall panels retrofitted with frp composites.“ compos. struct., 119, 648-65. https:// doi.org/10.1016/j.compstruct.2014.09.047 triantafillou, t. c., papanicolaou, c. g. (2006). „shear strengthening of reinforced concrete members with textile reinforced mortar (trm) jackets.“ materials and structures, 39, 93-103. https://doi. org/10.1007/s11527-005-9034-3 rui cardoso ph.d researcher at c-made c-made, beira interior university, civil engineering and architecture faculty, 6201-001 covilha, portugal civil engineering designer at groupe stebat engineering office albertville, france main research area rehabilitation, strengthening, building heritage address beira interior university, civil engineering and architecture faculty, 6201-001 covilha, portugal. e-mail: rui-cardoso@ubi.pt about the author https://doi.org/10.5755/j01.sace.23.2.21426 https://doi.org/10.5755/j01.sace.23.2.21426 https://doi.org/10.1533/9781845697037 https://doi.org/10.1061/(asce)0733-9445(1997)123:5(680) https://doi.org/10.1061/(asce)0733-9445(1997)123:5(680) https://doi.org/10.1061/(asce)cc.1943-5614.0000110 https://doi.org/10.1061/(asce)cc.1943-5614.0000110 https://doi.org/10.1016/j.conbuildmat.2012.11.080 https://doi.org/10.1016/j.conbuildmat.2012.11.080 https://doi.org/10.1016/j.engstruct.2015.02.006 https://doi.org/10.1016/j.engstruct.2015.02.006 https://doi.org/10.1061/(asce)0733-9445(1990)116:6(1565) https://doi.org/10.1061/(asce)0733-9445(1990)116:6(1565) https://doi.org/10.1016/j.compstruct.2014.09.047 https://doi.org/10.1016/j.compstruct.2014.09.047 https://doi.org/10.1007/s11527-005-9034-3 https://doi.org/10.1007/s11527-005-9034-3 journal of sustainable architecture and civil engineering 2021/1/28 106 *corresponding author: raimondas.sadzevicius@vdu.lt assessment on the technical state of spillway concrete gravity dams in lithuania received 2020/10/12 accepted after revision 2021/05/20 journal of sustainable architecture and civil engineering vol. 1 / no. 28 / 2021 pp. 106-117 doi 10.5755/j01.sace.28.1.27694 assessment on the technical state of spillway concrete gravity dams in lithuania jsace 1/28 http://dx.doi.org/10.5755/j01.sace.28.1.27694 raimondas šadzevičius*, rytis skominas, algirdas radzevičius vytautas magnus university, institute of hydraulic engineering, universiteto 10, lt–53361, akademija, kaunas district, lithuania introduction spillway concrete gravity dams are exposed by loads and environment causing deterioration process. the article presents the concrete structure deteriorations, defects and technical state evaluation results of 34 lithuanian spillway concrete gravity dams performed in 2006–2018. the typical deteriorations are: in piers’– crumbled protective layer of concrete, its corrosion, reinforcement corrosion, cracks in concrete, chipped edges; in spillway constructions’– concrete corrosion, bio–corrosion, concrete corrosion caused by cavitation; in outflow constructions – concrete corrosion, bigger cracks and deformations. according to results of technical state research, it was found that only 3% (1 scgd) dams are in good technical state, 27% (9 scgd) – moderate, 47% (16 scgd) – satisfactory, 12% (4 scgd) – unsatisfactory and 12% (4 scgd) – in critical state. keywords: deterioration, environmental impact assessment, spillway concrete gravity dams, technical state. spillway concrete gravity dams (hereinafter – scgd) are rather popular because they are good enough to a pass a greater floodwater discharges and ice. in lithuania’s conditions such discharges are over 100–150 m3/s (damulevičius and vyčius 2008, damulevičius et al. 2009, ruplys 1988). abroad various propositions are presented (hydraulics of dams and river structures 2004, novak et al. 2007, tanchev 2005). lithuanian scgds are designed, built and maintained in accordance with the requirements of construction technical regulations (str 2.02.06:2004 2004, str 2.05.15:2004 2004, str 2.05.14:2005 2005, str 2.05.18:2005 2005, str 1.03.07:2017 2017, hidrotechnikos statinių projektavimas 2001, hidrotechninė statyba 2000). scgds are usually included into the combined hydroscheme, which include, for example, embankment dam, hydropower plant (hereinafter – hpp) structure and other hydraulic structures. such and the most remarkable lithuanian scgd is in the hydroscheme of kaunas hpp. its maximum afflux (head difference) reaches 20 m, the design flood discharge is 3990 m3/s. nowadays here are possibilities to build a navigation sluice or lift in kaunas hpp hydroscheme and fish pass or fish lift. worldwide scgds that are more impressive are built. the tallest of them are: the grande dixence in switzerland with 285m height (grande dixence dam 2020) and diamer basha (formerly called basha) with 272m height (big dams 2020). many rather large scgds are built in usa, russia and in other countries which are mountainous and where strong, rocky soils prevail. these dams are designed in accordance with the requirements of construction technical regulations (em 1110–2– 1603 1990, em 1110–2–2104 2003, em 1110–2–2100 2005, em 1110–2–2200 1995, em 1110–2–2201 107 journal of sustainable architecture and civil engineering 2021/1/28 1994, sniip 33–01–2003 2004). all the hydraulic structures (hereinafter – hs), including spillway concrete gravity dams, are used in complicated conditions of the environmental impact: they are affected by natural (atmosphere, freezing–thawing cycles, ice and swimming solids or sediments abrasive impact, atmospheric precipitation, wind and storm, wave blows; periodical wetting; solar radiation, collapsing impacts; rockslides, earthquakes, etc.) and various technological factors. due to these factors, various deteriorations appear in the hs constructions; they reduce the bearing capacity of constructions (or spillway) to water pressure, technical state of scgd constructions decreases. causes of distress and deterioration of concrete are described very detail in standard em 1110–2–2002 (em 1110–2–2002 1995). it is known, concrete ageing, vibrations in the foundations, accumulation of sediments, water erosion are main factors that reduces dams resistance to failure (safety of existing dams – evaluation and improvement 1983, icold 1995). the threats (initiating events), 48 hazards, defined may lead to the different modes of failure, are described in work (almog 2011), but some of them – for example, earthquake loading are not actual in lithuania. the numbers of large dams are growing taking only the approximately 36 000 large dams listed in the world register of dams there have been around 300 reported accidents (icold 1995), (icold 2020, chanson 2000). some safety evaluation methods of hpp are described in scientific literature (safety of existing dams – evaluation and improvement 1983). there are about 620 potentially dangerous ponds with hydraulic structures (if water head is 4 m or more or in ponds accumulated water volume is more then 100000m3) in lithuania (tvenkinių katalogas 1998). in lithuania, dams’ observations and, to a certain extent, researches have been carried out since the dams were built, nevertheless the greatest attention has been focused on the field observations of earthfill dams (damulevičius 2001, damulevičius and vyčius 2007, šadzevičius et al. 2013). the biggest hydroschemes in lithuania are: kruonis pshep and kaunas hep. the technical state of these objects is monitored, controlled using regulations for maintenance (šikšnys 2007, skripkiūnas et al. 2006). technical state over 300 dams in lithuania were investigated by the specialists of water and land management faculty at the vytautas magnus university (hereinafter – vdu). main attention has been paid to these reinforced concrete (hereinafter –rc) hydraulic structures and constructions: rc slabs for earthfill dams slope protection (damulevičius and vyčius 2007), (šadzevičius 2002, šadzevičius et al. 2011); culverts and service bridges (natūrinių ir anketinių duomenų… 2009); service bridges in spillways (šadzevičius and mikuckis 2010); retaining (wing) walls (šadzevičius et al. 2009). at the same time studies of hs technical state evaluation were carried out (damulevičius et al. 2001, damulevičius and vyčius 2007, šadzevičius et al. 2013, šadzevičius et al. 2001, patašius et al. 2009). the researches of the scgd reinforced concrete constructions state were carried out in 1999–2005 by the specialists of the department of building constructions in lithuanian university of agriculture; the results were generalized in the report (natūrinių ir anketinių duomenų… 2009) and in the paper‘s (damulevičius et al. 2009), (šadzevičius et al. 2013). analysis of these, early performed investigations results, shows that currently valid dams’ maintenance regulations should be improved, because of insufficient information about the technical state evaluation process, deterioration of concrete on the safety and reliability of rc hydraulic structures. the purpose of this research is to describe the main indices and causes of deteriorations appearing in lithuanian spillway concrete gravity dams, to evaluate the changes of technical state of dams and according to the results of investigation propose the expressions for selecting proper covering concrete layer of designing new reinforced concrete spillways. materials and methods in 2006–2018 the spillway concrete gravity dams were inspected in 15 districts of lithuania: kėdainiai (8 dams), marijampolė (6 dams) and in some other regions of lithuania. taking into account the materials used for construction, the acting head and ground soil, the investigated objects belong to the consequence classes cc1 and cc2 (str 2.02.06:2004 2004). journal of sustainable architecture and civil engineering 2021/1/28 108 the following constructions’ diagnostic methods were used during the investigation of deteriorations’ state changes in spillways: 1. documentation review; 2. visual–instrumental method; 3. nondestructive (instrumental with a rebound hammer of concrete) and destructive (core sampling) methods were used for the estimation of concrete compressive strength in accordance with normative documents en 12504-1:2009, en 12504–2:2012, cen/tr 17086:2020, en 206:2013+a1:2017, laboratory tests for evaluation density (en 12390-7:2019/ac:2021), water absorbability (lst 1413.10:1997/p:2020), frost resistance (lst 1428-17:2016), but all results are not presented in this paper due the size of paper. documentation review – the analysis of design (work drawings and construction projects) and other archival documentation (technical maintenance records, rules of dam maintenance, inspections reports). visual–instrumental method (durcheva 1988, malakhanov 1990) is applied for scgd field investigations. noticed defects (broken corners or edges of surface, stratified concrete, etc.)) and deteriorations (deteriorated and destroyed concrete covering layer, steel corrosion, etc.) and their intensity were analyzed according to dams’ maintenance regulations (em 1110–2–2002 1995, the norwegian regulations for planning… 1996, em 1110–2–4300 1987). during expeditions and field investigations the location of damaged constructions, the types of deteriorations and their geometrical data (area, depth) were determined. using simple instruments (a ruler, sliding caliper, etc.) the detrioration of concrete surfaces, depths and paterns of cracks, deformations, scour, pittings, etc. were established. the photos of typical deteriorations of scgd were taken. according to the results of field investigations the technical state of scgd and whole hydroscheme was evaluated in accordance with deteriorations registered during the field observation and using the methodology given in the lithuanian construction technical regulations (str 1.03.07:2017 2017): scgd and hydroscheme were evaluated as functionally related elements main structures and auxiliary structures. technical state evaluation was performed using quantitative indices and calculating averages of defectiveness points (bu,) in ten points criterion system (0 points – ideal state, 10 points – element’s emergency state) following evaluation criteria given in lithuanian construction technical regulations (str 1.03.07:2017 2017). if one of main elements which determines scgd reliability is evaluated from 8.1 to 10.0 defectiveness points, then the technical state of the whole hydraulic structure is evaluated by the same points. if the main elements with defectiveness points from 8.1 to 10.0 are absent, overall (total) points (bu) of hs technical state are calculated according to the following formula: account the materials used for construction, the acting head and ground soil, the investigated objects belong to the consequence classes cc1 and cc2 (str 2.02.06:2004 2004). the following constructions’ diagnostic methods were used during the investigation of deteriorations’ state changes in spillways: 1. documentation review; 2. visual–instrumental method; 3. nondestructive (instrumental with a rebound hammer of concrete) and destructive (core sampling) methods were used for the estimation of concrete compressive strength in accordance with normative documents en 12504-1:2009, en 12504–2:2012, cen/tr 17086:2020, en 206:2013+a1:2017, laboratory tests for evaluation density (en 12390-7:2019/ac:2021), water absorbability (lst 1413.10:1997/p:2020), frost resistance (lst 1428-17:2016), but all results are not presented in this paper due the size of paper. documentation review – the analysis of design (work drawings and construction projects) and other archival documentation (technical maintenance records, rules of dam maintenance, inspections reports). visual–instrumental method (durcheva 1988, malakhanov 1990) is applied for scgd field investigations. noticed defects (broken corners or edges of surface, stratified concrete, etc.)) and deteriorations (deteriorated and destroyed concrete covering layer, steel corrosion, etc.) and their intensity were analyzed according to dams’ maintenance regulations (em 1110–2–2002 1995, the norwegian regulations for planning… 1996, em 1110–2–4300 1987). during expeditions and field investigations the location of damaged constructions, the types of deteriorations and their geometrical data (area, depth) were determined. using simple instruments (a ruler, sliding caliper, etc.) the detrioration of concrete surfaces, depths and paterns of cracks, deformations, scour, pittings, etc. were established. the photos of typical deteriorations of scgd were taken. according to the results of field investigations the technical state of scgd and whole hydroscheme was evaluated in accordance with deteriorations registered during the field observation and using the methodology given in the lithuanian construction technical regulations (str 1.03.07:2017 2017): scgd and hydroscheme were evaluated as functionally related elements main structures and auxiliary structures. technical state evaluation was performed using quantitative indices and calculating averages of defectiveness points (bu,) in ten points criterion system (0 points – ideal state, 10 points – element’s emergency state) following evaluation criteria given in lithuanian construction technical regulations (str 1.03.07:2017 2017). if one of main elements which determines scgd reliability is evaluated from 8.1 to 10.0 defectiveness points, then the technical state of the whole hydraulic structure is evaluated by the same points. if the main elements with , (1) where: b1, b2, ...., bn – evaluation points of separate hs elements; n – number of evaluated hs elements. the calculated points of hs technical state (bu) are rounded up or down in limits of 0.1(str 1.03.07:2017 2017). results in this paper the results of research and analysis of 34 scgd technical state in 15 districts of lithuania are presented. n bbb b nu +++ = ...21 (1) where: b1, b2, ...., bn – evaluation points of separate hs elements; n – number of evaluated hs elements. the calculated points of hs technical state (bu) are rounded up or down in limits of 0.1(str 1.03.07:2017 2017). in this paper the results of research and analysis of 34 scgd technical state in 15 districts of lithuania are presented. the oldest scgd was built in 1847, the last one in 1997. the investigations were performed in 2006–2018. during the field observation, the main scgd defects were determined; the general evaluation of scgd technical state in defectiveness points were calculated (table 2) in accordance lithuanian construction technical regulations (str 1.03.07:2017 2017). the data of investigated scgd are presented in table 1 and fig. 1. results 109 journal of sustainable architecture and civil engineering 2021/1/28 table 1 the data of spillway concrete gravity dams no. name of hydroscheme year of construction (* year of reconstruction works) year of research general evaluation of scgd state bu, points 1 2 3 4 5 alytus district 1 kumečiai 1968 2009 4.4 jonava district 2 lokys 1988 2011 5.4 3 markutiškiai 1989 2011 6.7 kėdainiai district 4 akademija – dotnuva 1968 2006* 2011 4.6 5 angiriai 1980 2000 2006 3.2 6 kruostas 1953 2013 10 7 labūnava i 1977 2004 2012 4.7 8 labūnava ii 1991 2010 10 9 kėdainiai city 1972 2012 4.0 10 juodkiškis 1980 2001* 2011 4.7 11 urkos 1997 2010 9 kretinga district 12 darbėnai 1932 2009 3.2 13 kretinga park i 1878 1987 2006 3.9 lazdijai district 14 kapčiamiestis 1956 2007 4.1 marijampolė district 15 antanavas 1957 2004*, 2011* 2011 5.2 16 kazlai i 1991 2009 3.8 17 kazlai ii 1935 2006 7.8 18 marijampolė i 1957 2008* 2011 4.5 19 marijampolė ii 1974 2004* 2011 4.4 20 netičkampis 1951, 1991* 2009 7.3 pakruojis district 21 dvariukai 1982 2011 3.7 panevėžys district 22 factory „ekranas“ 1980 2018 3.4 journal of sustainable architecture and civil engineering 2021/1/28 110 no. name of hydroscheme year of construction (* year of reconstruction works) year of research general evaluation of scgd state bu, points 23 jotainiai 1987 2008 4.5 pasvalys district 24 pasvalys city 1895 2008 5.1 25 švobiškis 1919 2008 5.2 prienai district 26 jundeliškes 1958 2011 6.1 raseiniai district 27 paupys 1972 2012 5.5 šilutė district 28 vilkenai 1847 2007 2.8 ukmergė district 29 taujėnai 1985 2010 4.0 30 vepriai 1974 2010 5.6 utena district 31 satarečius 1975 2008* 2010 1.0 telšiai district 32 pasruojė 1964 2012 9.0 33 sukončiai 1953 2012 4.2 34 ubiškė 1977 2012 4.5 fig. 1 the histogram of construction years of investigated objects graphically the results of the scgd erection are presented in fig. 1. the most intensive period of scgd constructing was in 1960–1980. during this period were built 13 investigated objects. according to the data presented in fig. 1 main part of investigated scgd are more than 40 years old, only few objects are exploited less than 30 years. the distribution of the number of investigated scgd in lithuania by district is shown in fig. 2. the results of 34 scgd technical state investigations are presented graphically in fig. 3. summarized results showed that only 3% (1 scgd) dams are in good technical state, 26% (9 scgd) – moderate, 47% (16 scgd) – satisfactory, 12% (4 scgd) – unsatisfactory and 12% (4 scgd) – in critical state. 111 journal of sustainable architecture and civil engineering 2021/1/28 fig. 2 distribution of investigated scgd by district the maximum of dams in critical state (3) was founded in kėdainiai district. scgd in unsatisfactory or critical state can be potencialy dangerous for the dam surroundings and repair works must be performed immediately. kruostas, labūnava ii, urkos scgd in kėdainiai district and pasruojė scgd in telšiai district must be rehabilitated or demolished as quick as possible. fig. 3 scgds technical state category founded in 2006–2018 analysing results of pier constructions’ technical state research it was established that after reconstruction, the state of piers’ constructions in akademija–dotnuva, antanavas, marijampolė i and marijampolė ii and another scgds improved, however in hydroschemes, where the reconstruction haven’t taken place, the state of piers worsens, it has especially worsened in kruostas, netičkampis scgd. main piers’ dete good 3% moderate 26% satisfactory 47% unsatisfactory 12% critical 12% riorations in the investigated scgds are the following: crumbled protective layer of concrete, its corrosion, reinforcement corrosion, cracks in concrete, chipped edges, etc. analysing the results of spillway base technical state research, it was established that before reconstruction in akademija – dotnuva and antanavas scgds, these constructions had been in an unsatisfactory (bad) technical state (6.5 – 7.0 points). the technical state of spillway base was evaluated as average in those scgds, where the reconstruction haven’t taken place, still, the technical state of these constructions has especially worsened in netičkampis scgd (7.5 points, unsatisfactory (bad) state) and kruostas scgd where it has worsened from 5.5 points in 1999 to 10.0 points in 2005–2011. main spillway constructions’ deteriorations in the investigated scgds are the following: concrete corrosion, bio–corrosion, concrete corrosion caused by cavitation etc. analysing the results of outflow constructions’ state research it was found out that before reconstruction in akademija – dotnuva and antanavas scgds, these constructions had been in a very bad state (9.0 points) the failure of the whole structure was possible due to considerable deteriorations of the constructions. the technical state of outflow constructions in other scgds was evaluated as unsatisfactory (6.1–8.0 points) and only in labūnava and kazlai scgds the technical state of these constructions was evaluated as satisfactory (4.1–6.0 points). the main deteriorations of outflow constructions are the signs of concrete corrosion, noticed in all the investigated scgds. deformations of retaining walls were noticed in kėdainiai city, kruostas, marijampolė i, netičkampis scgds. main journal of sustainable architecture and civil engineering 2021/1/28 112 causes of scgds deformations and deteriorations are: insufficient supervision (antanavas and kudirkos naumiestis scgd), poor quality of work and low quality of used construction materials (kruostas scgd). relatively rapid deterioration of kruostas hs was due to low quality of materials – after the core drilling was found clay in some samples (specimen no.7) and laboratory testing of core samples showed the small compressive strength of concrete (table 2). during increased accumulation of deteriorations (in some cases of very aggressive environment (acidic brown water from exploited peatbog), insufficient supervision of hs (e.g. kruostas, kudirkos naumiestis scgd) the scgds technical state changing from unsatisfactory to critical. table 2 the main physical– mechanic properties of concrete in the kruostas scgd structure physical– mechanic properties of concrete thickness of damaged, surface layer, cm specimen number description and location of investigated part compression strength of specimen fcube (mpa) density of hardened concrete ρ, kg/m3 water absorption, wm % frost resistance f, cycles nondestructive method destructive method (cylindrical cores) 1 2 3 4 5 6 7 8 1 wall of turbine hall 19.5 19.5 2227 8.32 34 0 2 wall of hpp from lp side 20.8 14.6 2146 9.23 16 3-5 3 right wall of hpp from lp side 25.0 35.5 2235 8.45 31 1-2 4 l left side of fish pass wall from lp near gates 33.6 24.4 2211 9.37 14 <1 4 r the right side of fish pass wall from lp 30.2 15.2 2071 10.99 1-2 5 ii pier from lp, left side 49.2 42.1 2282 6.14 118 < 1 6 iii pier from lp, left side 49.1 23.4 2245 7.04 75 < 1 7 abutment left side, external 20 cm layer 46.0 27.5 2204 9.32 29 1-10 7 abutment left side, internal layer * 12.4 5.8 remarks: * core no.7 made from two different composition of concrete hpp – hydropower plant, lp– lower pool side. 113 journal of sustainable architecture and civil engineering 2021/1/28 the results of non-destructive testing (table 2) shows that the highest concrete compression strength was determined in the structures of ii and iii piers fcube = 49.2 mpa, the lowest concrete compression strength was foundend in the left abutment fcube = 12,4 mpa. the results of destructive testing shows the lower values of concrete compression strength at the same structures – ii pier fcube = 42.1 mpa and iii pier fcube = 23.4 mpa, left abutment fcube = 5.8 mpa. it is known (šadzevičius et al 2015), that the rebound hammer test shows only the state of the surface of concrete. the surface of concrete has higher values (due carbonisation), so the result of compressive strength obtained by examining the drilled cores is more reliable. discussionthe analysis of results of lithuania scgd technical state evaluation performed in our research shows, that in investigated regions scgd technical state is getting worse, due to insufficient supervision, ageing and deterioration of structures. during normal maintenance of hs the damages are accumulate slowly, so the technical state has remained unchanged than repair works performed in some scgd. analysing the results of scgds constructions’ technical state research it was established that, similar deteriorations are mentioned in the generalized report of state researches of 287 scgds in norway, which can be found in scientific literature (jensen 2001). on the basis of these researches, the main reinforced concrete deteriorations in the investigated dams and their causes were established: reinforcement corrosion (noticed in 19 % of researched dams), concrete corrosion (18 %), deteriorations caused by frost (50 %), concrete erosion (47 %), water leakage (21 %), deformations (20 %), concreting defects (43 %), vertical and horizontal cracks noticed in 53% to 56% of the investigated dams; 36% have map cracking and damages in the dam arches. above listed main causes of hs defects and deteriorations in norway scgd are typical and founded in reinforced concrete hs of lithuania scgd too. the results of field investigations performed on 32 earthfill dams shows, that main damages of rc slabs for slope protection are deterioration of cover layer and collapsing of junctures, noticed in 30% and 50% of objects. (damulevičius, v.; vyčius 2007, šadzevičius 2002, šadzevičius et al. 2011). comparing the research results carried out in 2006–2018 with the results of previous researches (1999–2005) it was found out that the technical state has hardly changed in kruostas, labūnava ii, urkos marijampolė ii, antanavas, pasruojė scgds; the technical state has worsened in akademija–dotnuva, juodkiškis, kazlai, jundeliškes, markutiškiai and netičkampis scgds; the state has improved due to reconstruction in marijampolė i scgd. the worst technical state was established in kruostas and labūnava ii (10.0 points), urkos and pasruojė (9.0 points) scgds. the data of research presented are given for designing new reinforced concrete (hereinafter –rc) spillways or repairing the deteriorated parts of structures timely. 30 40 mm concrete covering layer, protecting reinforcement from corrosion and its condition shows the durability of whole structure. during research it was noticed the 30 mm concrete covering layer (constructed according design norms of former ussr) of reinforced concrete structures was deteriorated very often. if hs are made from concrete with low quality of materials rc surfaces are damaged much more (šadzevičius 2007). the maximum speed of deterioration (pitting) deepening (3.67 ÷ 5.06 mm/year) was noticed in structures made of concrete with low average concrete compression strength fc = 5.1 ÷ 7.1 mpa from antanavas and kazlai old scgd. nowadays covering layer of rc structures must be 40 mm and made from concrete, which compression strength 37 mpa (str 2.05.18:2005 2006). using our estimated durability indices t40mm (šadzevičius et al. 2010) for designed reinforced concrete spillways, can be chosen concrete covering layer of rc structures, that reinforcement won’t uncover during foreseen time: journal of sustainable architecture and civil engineering 2021/1/28 114 fig. 4 the relationship between concrete compression strength fcfrost resistance f and durability indices t40mm based on kruostas scgd technical state investigations t40 mm = –17.6+3.33· fc , (2) where t40 mm – functioning period of a 40 mm thick covering layer of the hs expressed in years; fc – average compression strength of concrete, mpa. the application of proposed dependance (2) is illustrated in fig. 4 calculations performed on kruostas scgd investigation results presented in the table.2. the new dependence concrete compression strength fcfrost resistance f was created on the basis of main physical– mechanic properties of concrete in the kruostas scgd (fig.4). f = 0,0607fc2 0,3827fc + 5,0118 r² = 0,597 0,0 20,0 40,0 60,0 80,0 100,0 120,0 140,0 0 20 40 60 80 100 120 140 0 10 20 30 40 50 t 4 0 m m , y ea rs fr os t r es is ta nc e f, cy cl es concrete compression strength fc, mpa f t40 mm f = 0,0607fc2 0,3827fc + 5,0118 r² = 0,597 0,0 20,0 40,0 60,0 80,0 100,0 120,0 140,0 0 20 40 60 80 100 120 140 0 10 20 30 40 50 t 4 0 m m , y ea rs fr os t r es is ta nc e f, cy cl es concrete compression strength fc, mpa f t40 mm f = 0,0607fc2 0,3827fc + 5,0118 r² = 0,597 0,0 20,0 40,0 60,0 80,0 100,0 120,0 140,0 0 20 40 60 80 100 120 140 0 10 20 30 40 50 t 4 0 m m , y ea rs fr os t r es is ta nc e f, cy cl es f t40 mm f = 0,0607fc2 0,3827fc + 5,0118 r² = 0,597 0,0 20,0 40,0 60,0 80,0 100,0 120,0 140,0 0 20 40 60 80 100 120 140 0 10 20 30 40 50 t 4 0 m m , y ea rs fr os t r es is ta nc e f, cy cl es concrete compression strength fc, mpa f t40 mm conclusions according to the data presented in fig. 4, a 40 mm covering layer made of weak concrete (fc = 5.8 mpa) will be deteriorated in 5 year of functioning, while the one made of strong concrete (fc = 42.1 mpa) will be deteriorated in 122.6 years of functioning. the relationship between frost resistance f and average compression strength of concrete fc could be expressed: f = 0,0607fc2 – 0,3827fc + 5,0118 (3) where f – frost resistance expressed in cycles; fc – average compression strength of concrete, mpa. according to the data presented in fig. 4, the structures in kruostas scgd made from strong concrete (fc = 42.1 mpa) has frost resistance f=118 cycles. these structures are less deteriorated. the most suitable variant for the repair of reinforced concrete in hs is to use cement mortar modified with expansive admixture and to properly prepare the concrete surface (the minimum roughness index of concrete surface must be rimin=2.92) (skominas et al. 2017). 1. according to the technical state investigation of 34 lithuanian spillway concrete gravity dams performed in 2006–2018, the main deteriorations in the structures of investigated objects are: _ in piers’– crumbled protective layer of concrete, its corrosion, reinforcement corrosion, cracks in concrete, chipped edges; _ in spillway constructions’–bio–corrosion, concrete corrosion caused by cavitation; _ in outflow constructions – concrete corrosion, bigger cracks and deformations. 115 journal of sustainable architecture and civil engineering 2021/1/28 references 2. the typical causes of deterioration and deformations of spillway concrete gravity dams are: _ lack of maintenance and insufficient supervision, _ poor quality of work and low quality of used construction materials, _ it was established, that main deteriorations of concrete structures are rapidly in progress and caused by the environmental factors (periodical wetting, freezing–thawing cycles, ice and swimming solids or sediments abrasive impacts, wave blows, cavitation and etc.). 3. according to results of technical state investigations of 34 lithuanian scgd carried out in 2006– 2018 by vdu researchers, it was found that only 3% (1 scgd) dams were in good technical state, 27% (9 scgd) – moderate, 47% (16 scgd) – satisfactory, 12% (4 scgd) – unsatisfactory and 12% (4 scgd) – in critical state. 4. the worst technical state was established in kruostas, labūnava ii, urkos scgd in kėdainiai district and pasruojė scgd in telšiai district, so these dams must be rehabilitated or demolished as quick as possible. 5. according to the results of investigation proposed expressions (2 and 3) for selecting proper covering concrete layer of designing new reinforced concrete spillways. the most suitable variant for the repair of the damaged parts of reinforced concrete spillways is to use cement mortar modified with expansive admixture and to properly prepare the concrete surface. almog, e.; kelham, p.; king, r. modes of dam failure and monitoring and measuring techniques. bristol: environment agency, 2011. big dams. available online: https://www.hydroreview.com/2009/03/01/big-dams/ (accessed on 30 june 2020). cen/tr 17086:2020. further guidance on the application of en 13791:2019 and background to the provisions. chanson, h. a review of accidents and failures of stepped spillways and weirs. proc. instn civ. engrs water and maritime engrg, uk, 2000, vol. 142, pp. 177188. https://doi.org/10.1680/wame.2000.142.4.177 damulevičius, v., rimkus, z., vyčius, j. investigation of the 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baseino gelžbetoninių ramtų plyšių klasifikacija pagal pavojingumą konstrukcijai. water management engineering, 2009, 35(55): pp. 110-116. šadzevičius, r.; sankauskienė; t.; mikuckis, f. durability of concrete covering layer of spillways. proceedings of 15th international conference mechanika, kaunas, lithuania, april 8-9, 2010. kaunas: technologija, 409-414. šadzevičius, r.; vaišvila, k. a.; lindišas, l. the research of deterioration of reinforced concrete stuctures functioning in the alternative level of water 117 journal of sustainable architecture and civil engineering 2021/1/28 about the author this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/ ). engineering constructions, water management engineering, 2001, 18(40): pp. 47-52. šadzevičius, r.; sankauskienė, t.; milius, p. comparison of concrete compressive strength values obtained using rebound hammer and drilled core specimens. rural development 2015: towards the transfer of knowledge, innovations and social progress: proceedings of the 7th international scientific conference, 19-20th november, 2015, aleksandras stulginskis university, lithuania: pp. 1-6. https://doi.org/10.15544/rd.2015.011 šiksnys, a. kruonio hae hidrotechnikos statinių būklės vertinimo metodikos ir vertinimo rodiklių reikšmių nustatymas. kaunas: lžūu, 2007. tanchev, l. dams and appurtenant hydraulic structures. london: taylor&francis, 2005. the norwegian regulations for planning, construction and operation of dams. norway, oslo: norwegian university press, 1996. tvenkinių katalogas. aplinkos apsaugos ministerija, hidrografinio tinklo tarnyba. kaunas, 1998. raimondas šadzevičius assoc.prof. dr. vytautas magnus university, institute of hydraulic engineering main research area the evaluation of technical state of hydraulic structures and agricultural buildings. other directions of research – to evaluate the new principles of repairing or reconstruction, the application of new materials in the reconstruction of hydroshemes and agricultural buildings in lithuania. address universiteto 10, lt–53361, akademija, kaunas district, lithuania tel. +37060097176 e-mail: raimondas.sadzevicius@vdu.lt rytis skominas assoc.prof. dr. vytautas magnus university, institute of hydraulic engineering main research area durability, repair and maintenance of hydraulic structures. other directions of research – green concrete. address universiteto 10, lt–53361, akademija, kaunas district, lithuania tel. +37060014067 e-mail: rytis.skominas@vdu.lt algirdas radzevičius assoc.prof. dr. vytautas magnus university, institute of hydraulic engineering main research area the modelling of sewerage systems, hydraulic structures, application of nano technologies on the improvement of mortars properties. address universiteto 10, lt–53361, akademija, kaunas district, lithuania tel. +37068736574 e-mail: algirdas.radzevicius@vdu.lt journal of sustainable architecture and civil engineering 2020/2/27 96 *corresponding authors: aleksejs.prozuments@rtu.lv, anatolijs.borodinecs@rtu.lv survey based evaluation of indoor environment in an administrative military facilityreceived 2020/06/25 accepted after revision 2020/08/24 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 96-107 doi 10.5755/j01.sace.27.2.26079 survey based evaluation of indoor environment in an administrative military facility jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.26079 aleksejs prozuments*, anatolijs borodinecs*, jurgis zemitis institute of heat, gas and water technology, riga technical university, 6b/6a kipsalas str, riga, latvia. introduction unclassified buildings building sector is a major energy consumer, accounting for 40% of total energy use across the developed countries (yüksek and karadayi 2017), (luo et al. 2019). the energy efficiency of the existing building stock may be substantially reduced through various deep retrofit and energy renovation programs (eliopoulou and mantziou 2017), (borodinecs et al. 2017). however, majority of the energy efficiency incentive programs are focused on residential and public buildings, while the implementation of energy efficiency measures in the so-called unclassified buildings is not adequately addressed by the governmental and municipal support (borodinecs, geikins, and prozuments 2020). unclassified buildings encompass variety of military structures, prison facilities, security force, police and fire station buildings (geikins et al. 2019), (anon 2018). military facilities feature distinctive requirements with regards to building technical and structural design, material use and indoor environmental conditions, as these buildings serve specific purpose and the personnel occupying the premises may wear uniform or protective clothing (administrative staff, special forces, training personnel etc.), that can greatly affect their satisfaction level with thermal comfort and productivity. in order to acquire data on the actual indoor environment conditions and obtain a feedback from the occupying personnel on their satisfaction level with the indoor environment in an administrative military building situated in a special purpose military compound, a series of indoor air quality measurements (temperature, humidity, co2 level) and a survey on indoor air quality and thermal comfort was conducted in different premises of the administrative office building. a total of 73 respondents occupying the building participated in the survey. the results of the conducted survey revealed that there is a high degree of dissatisfaction with the indoor environment in military buildings, that is attributed to inadequate ventilation and overtemperature. that matched the collected indoor environmental quality data, forming a relationship between poor energy management and poor energy efficiency, that can in turn lead to unsatisfactory indoor environmental conditions. the study reiterates the need to address the poor current technical state of unclassified building stock, emphasizes the call for developing clear regulatory requirements for newly-constructed unclassified buildings and thorough feasibility assessment for renovation projects. keywords: thermal comfort, indoor air quality, occupant survey, military buildings. 97 journal of sustainable architecture and civil engineering 2020/2/27 unclassified buildings feature distinctive requirements with regards to indoor environmental conditions (iec), as these buildings serve specific purpose and the personnel occupying the premises may wear uniform or protective clothing (e.g., police officers, firefighters, military personnel etc.), that can greatly affect their satisfaction level with thermal comfort and productivity (wang et al. 2019), (casaru 2009). the majority of unclassified buildings in latvia were constructed during soviet union period between 1945 and 1990, when latvia was part of union of soviet socialist republics (ussr). during that period building design and construction had little or no emphasis on energy efficiency efforts, as the energy prices were relatively low and cost optimization measures focused on short term rather than long term investments, putting fast construction time and use of rigid, durable materials ahead of sustainability strategies, such as building energy performance (carlsmith et al. 1990). these buildings feature heavy brick external walls and unheated attics with poor thermal insulation. one-pipe heating system and natural ventilation are commonly used technical solutions, that is obsolete and inefficient in terms of energy consumption. in addition to initial poor technical conditions, the majority of unclassified buildings have not undergone proper energy management or energy audits due to enhanced security, data protection and limited access to these buildings (borodinecs et al. 2020). energy performance of military buildings according to the data provided by the ministry of economics of the republic of latvia the average annual energy consumption for heating (and ventilation where relevant) in military buildings (constructed before 1990) is 212 kwh/m2, while in some military buildings this figure reaches 300 kwh/m2 (anon n.d.). this indicates the need to perform an energy audit to identify the major factors affecting high energy consumption. fig. 1 shows that the average energy consumption in military buildings reduces in line with the building construction year, suggesting that certain design and construction approaches were implemented to enhance building energy performance over time. fig. 1 calculated and measured total annual energy consumption for heating (and ventilation) in the investigated military facilities the energy performance requirements for military buildings is not defined by any local or regional eu norms, therefore, to perform calculations or set design criteria, energy auditors and engineers typically take into consideration simplified input data that is used for civil buildings (residential, public etc.) (borodinecs et al. 2020). the measured energy consumption in military buildings significantly exceeds that of the residential buildings, that consume on average 180 kwh/m2 per annum. the investigated administrative military building was constructed in 1963 when normative u-value requirements for different building elements were not specified. in fact, up until 1990s in latvia and other post soviet region countries there was not strict regulatory environment with regards to building energy efficiency. after gaining an independence from soviet union, the ministry of architecture and construction of latvia imposed local energy efficiency standard, that was later journal of sustainable architecture and civil engineering 2020/2/27 98 followed by a more stringent national building standard lbn 002 (thonipara et al. 2019). a decade later, after becoming a member of the eu, the local building energy efficiency standards in latvia were tightened further with the general aim to meet the common energy criteria requirements among the eu member countries (anon 2007), however as of today unclassified building stock is still deemed obsolete in terms of energy performance, as only a handful of unclassified buildings were constructed (or renovated) after 1990s to comply with the updated regulatory environment. as such, majority of the military building stock lacks fundamental façade upgrades with added thermal insulation and moisture prevention as well as mechanical ventilation system to provide fresh and conditioned air into premises. according to simulation results conducted for fire stations, a typical façade retrofit of 50mm added external insulation layer to the building facades came out to 30% of total thermal energy savings used for space heating, while a deep retrofit that includes façade renovation, as well as hvac system upgrade including the heat recovery generated 86% of thermal energy savings (borodinecs et al. 2020). oftentimes, poor energy efficiency in the building goes in line with poor indoor comfort, as buildings featuring poor energy performance present considerably higher potential of overcooling/ overheating, draft and other issues compromising indoor environment (wells et al. 2015). for a successful design of healthy, energy efficient and satisfactory indoor environment conditions, it is critical to account for interdependencies in a human-built environment system (šujanová et al. 2019). therefore, this study aims to determine the occupant satisfaction level with the indoor environment in the investigated building and link the factors of the unsatisfactory indoor environment conditions (iec) and the poor energy performance of a building via occupant survey. methods iaq measurements in order to acquire data on the actual indoor environment conditions and obtain a feedback from the occupying personnel on their satisfaction level with the iec in an administrative military facility, a series of iaq measurements (temperature, humidity, co2 level) were carried out and a survey on the occupant satisfaction with the indoor air quality and thermal comfort was conducted in different premises of an investigated military building in riga during the third decade of february 2019. the average recorded temperature in riga during the 7 days of the continuous measurements was 0,4 oc, while the average daytime temperature (during the occupancy hours from 8.00 – 18.00) was 1,3 oc (anon 2019b), (anon 2019a). the extech sd800 co2, temperature and air humidity data logger was used to carry out the measurements. within the framework of this study an administrative military personnel facility was investigated, where a total of 73 respondents of different age and gender participated in the survey. as previously stated, the investigated building feature relatively poor thermal energy performance. occupant survey analysis after the technical inspection relating to the building #11 energy profile, the personnel occupying or performing their duties in the building were asked to fill out a survey. respondents were asked to fill in a questionnaire, consisting of the following questions (table 1). the fig. 2 extech sd800 data logger methods iaq measurements in order to acquire data on the actual indoor environment conditions and obtain a feedback from the occupying personnel on their satisfaction level with the iec in an administrative military facility, a series of iaq measurements (temperature, humidity, co2 level) were carried out and a survey on the occupant satisfaction with the indoor air quality and thermal comfort was conducted in different premises of an investigated military building in riga during the third decade of february 2019. the average recorded temperature in riga during the 7 days of the continuous measurements was 0,4 oc, while the average daytime temperature (during the occupancy hours from 8.00 – 18.00) was 1,3 oc (anon 2019b), (anon 2019a). the extech sd800 co2, temperature and air humidity data logger was used to carry out the measurements. figure 2. extech sd800 data logger. within the framework of this study an administrative military personnel facility was investigated, where a total of 73 respondents of different age and gender participated in the survey. as previously stated, the investigated building feature relatively poor thermal energy performance. occupant survey analysis after the technical inspection relating to the building #11 energy profile, the personnel occupying or performing their duties in the building were asked to fill out a survey. respondents were asked to fill in a questionnaire, consisting of the following questions (table 1). the questionnaire was designed to be brief and concise in order to increase reliability and validity of survey results, following the good survey practice guidelines (anon 1995). 99 journal of sustainable architecture and civil engineering 2020/2/27 questionnaire was designed to be brief and concise in order to increase reliability and validity of survey results, following the good survey practice guidelines (anon 1995). table 1 questionnaire question response options are you generally satisfied with the room temperature? yes/no evaluate your satisfaction/dissatisfaction level with the room temperature? 1 to 7 is there any unwanted air movement in the room, drafts? yes/no are you satisfied with the indoor air quality? yes/no evaluate your satisfaction/dissatisfaction level with the humidity in the room? 1 to 7 are there unpleasant odors in the room? yes/no are you satisfied with the acoustic condition of the room? yes/no additional questionnaire asking to specify sources of dissatisfactory comfort level. n/a thermal energy consumption the special purpose campus, where the administrative building is located contains a total of 15 buildings that serve different functions. the total area of the campus is 190 000 m2 and half of that area is occupied by a series of unclassified and military buildings connected to a district heating system network (military dormitories, warehouses, training facilities etc.). during the survey it was determined that the majority of the buildings have an uneven distribution of heat energy consumption, which is attributed to the fact that special purpose buildings have a rather unpredictable occupancy and occupant activity pattern. that activity pattern largely depends on various factors and is hard to align in a scheduled framework. after an inspection of all 15 buildings situated in the compound, it was determined that only 5 of the buildings were equipped with thermal energy meters (labelled as #5, #11, #12, #13 and #15). heat energy meters were installed mainly in those buildings with more or less regular energy consumption pattern. results and discussion fig. 3 thermal energy consumption (y axis: kwh/m2) in the investigated special purpose compound buildings journal of sustainable architecture and civil engineering 2020/2/27 100 fig. 3 illustrates the thermal energy consumption (kwh/m2) in 5 buildings of the military special purpose compound. buildings are labeled by numbers #5, #11, #12, #13 and #15. as seen in fig. 3 thermal energy consumption in building #13 drops down significantly after 2012, that is attributed to the renovation (building façade and hvac system upgrade). as a result, the average thermal energy consumption reduced from 204 kwh/m2 measured between 2010 and 2012 to 110 kwh/m2 measured between 2013 and 2016. building #11 (fig. 3) corresponds to the administrative building investigated in this study more thoroughly, with comparatively higher energy consumption than other buildings. another building that stands out is building #12 that serves as a dormitory for military personnel. the building features an increased energy consumption due to its age (constructed before 1970s) and is planned to be renovated soon. in this study an administrative military building (#11 in fig. 3) was investigated with regards to its annual energy performance (kwh/m2) and indoor environmental comfort. the research team effortlessly tried to gain access to do thorough measurements in all of the 5 buildings, however, due to security and classified nature of the military compound, the team was only granted access to conduct measurements and occupant survey in building #11, i.e., administrative military building. the investigated building was constructed in 1963 and its annual thermal energy consumption is in the ballpark of 180-220 kwh/m2 annually on average. since the building’s construction, it has not undergone neither any façade retrofits, nor any major system retrofit measures, except for an introduction of mechanical ventilation system, that has been installed in 1980s, however, has not been upgraded since. we were not able to gain more information on the ahu and the frequency (if any) of technical inspection and maintenance of the ahu or the ventilation system, therefore it was difficult to assess the designed performance of the system. the annual energy consumption calculation was carried out according to latvian cabinet of ministers regulation no. 348 “methodology for calculating the energy performance of a building” (minister of economic affairs and communications 2014) (equation 1): eannual = (σuiai + σψjlj + σχk + (vair ∙ c) ∙ 24 ∙ dheat ∙ (tin tout))/(1000 ∙ a) η ∙ (qint + qsol) (1) where: ui – heat transfer coefficient of the building construction element (w/(m 2∙k)); ai – the area of the respective construction element of the building prototype model (m 2); ψi – heat transfer coefficient of the linear thermal bridge (w/(m∙k)); li – length of the linear thermal bridge (m); χk – heat transfer coefficient of the point thermal bridge (w/∙k); vair – ventilation air volumetric flowrate (m3/h); c – air heat capacity per volume = 0.34 (wh/(m3×k)); dheat – number of heating days; tin – average set-point temperature in the assessment (heating or cooling) period ( oc); tout average external temperature in the calculation period ( oc); a – total floor area of the building (m2); η – gain use coefficient for heating in accordance with paragraph 99 of this regulation or standard lvs en iso 13790:2009 l [85]; qint – interior gains of the whole building in the assessment period t (wh); qsol – solar heat gains of the whole building in the assessment period t (wh). 101 journal of sustainable architecture and civil engineering 2020/2/27 the necessary building input data was acquired from building information system (bis) database (anon 2003). to compare the actual (measured) energy consumption vs theoretical (calculated) energy consumption, energy auditing and measurements were conducted in the same set of buildings throughout 2014-2016. as per the obtained results, the total average annual measured energy consumption for military buildings was 230 kwh/m2, while the average calculated energy consumption for military buildings – 153 kwh/m2 (33% lower than measured). the high discrepancy between the calculated and measured data may have occurred due to deviation in the input values (hot water consumption, indoor temperature, supply air exchange rate, airtightness of building envelope etc.) against the actual values. occupant survey analysis occupant survey analysis involved distributing the questionnaire (table 1) to the building occupants. the majority of the personnel occupying the building are dressed in military uniform, that has a clothing factor (clo) of 1.4. this was assumed as the averaged clo value for all building occupants. the metabolic activity rate (met) was assessed as 2.0 which corresponds to medium activity environment, even though for different occupants, the metabolic rate might vary from 1.0 to 3.0 met. it is also important to note that the research team were only granted a limited access to do necessary measurements in the premises of the administrative military building. the team was not authorized to contact the personnel and potential respondents neither in person nor via telephone or e-mail, and the questionnaires were distributed via the responsible administrative officer (team manager), so that the team had no control or any influence to receive as high and accurate response rate as possible or any additional feedback form the respondents. as a result, the number of completed and returned questionnaires was considerably lower than the number of personnel indicated on the administrative building registry. in overall, of presumed 145-150 regular occupants of the building (indicated on the registry), 73 responses came back for further analysis. the occupant survey was distributed in march 2019. the results of the conducted survey distributed to the occupying personnel revealed that there is a high degree of dissatisfaction with the iec in the investigated administrative military building. the majority of the respondents assessed the room temperature as dissatisfactory (43 out of 73). also, most respondents assessed indoor air quality as neutral on the scale from 1 to 7. the low satisfaction rate is attributed to inadequate air exchange and overheating in the warm season, when the heat gains due to solar radiation intensify and the fig. 4 distribution of respondents by age and gender (quantitative values and percentages) (calculated) energy consumption, energy auditing and measurements were conducted in the same set of buildings throughout 2014-2016. as per the obtained results, the total average annual measured energy consumption for military buildings was 230 kwh/m2, while the average calculated energy consumption for military buildings – 153 kwh/m2 (33% lower than measured). the high discrepancy between the calculated and measured data may have occurred due to deviation in the input values (hot water consumption, indoor temperature, supply air exchange rate, airtightness of building envelope etc.) against the actual values. occupant survey analysis occupant survey analysis involved distributing the questionnaire (table 1) to the building occupants. the majority of the personnel occupying the building are dressed in military uniform, that has a clothing factor (clo) of 1.4. this was assumed as the averaged clo value for all building occupants. the metabolic activity rate (met) was assessed as 2.0 which corresponds to medium activity environment, even though for different occupants, the metabolic rate might vary from 1.0 to 3.0 met. it is also important to note that the research team were only granted a limited access to do necessary measurements in the premises of the administrative military building. the team was not authorized to contact the personnel and potential respondents neither in person nor via telephone or e-mail, and the questionnaires were distributed via the responsible administrative officer (team manager), so that the team had no control or any influence to receive as high and accurate response rate as possible or any additional feedback form the respondents. as a result, the number of completed and returned questionnaires was considerably lower than the number of personnel indicated on the administrative building registry. in overall, of presumed 145-150 regular occupants of the building (indicated on the registry), 73 responses came back for further analysis. figure 4. distribution of respondents by age and gender (quantitative values and percentages). the occupant survey was distributed in march 2019. the results of the conducted survey distributed to the occupying personnel revealed that there is a high degree of dissatisfaction with the iec in the investigated administrative military building. the majority of the respondents assessed the room temperature as dissatisfactory (43 out of 73). also, most journal of sustainable architecture and civil engineering 2020/2/27 102 fig. 5 respondents’ satisfaction level with the room temperature (left) and indoor air quality (right) fig. 6 respondents’ satisfaction level with the indoor air humidity and indoor temperature respondents assessed indoor air quality as neutral on the scale from 1 to 7. the low satisfaction rate is attributed to inadequate air exchange and overheating in the warm season, when the heat gains due to solar radiation intensify and the daytime temperature exceeds 20oc (primarily may – september). reducing temperature in certain premises during the warm season would ensure higher iec satisfaction level among the personnel, as well as offer energy savings (if the overheating period overlaps with the heating season). the results of the survey are outlined in fig. 5 and 6. figure 5. respondents’ satisfaction level with the room temperature (left) and indoor air quality (right). figure 6. respondents’ satisfaction level with the indoor air humidity and indoor temperature. the analysis of the survey illustrates the issue of indoor comfort in the studied building. many respondents gave negative ratings on indoor air temperature, relative humidity, and air quality; however, the largest percentage expressed that they are neither satisfied nor dissatisfied with the iaq parameters, giving the score of 4. this may also be linked to some respondents being comfortable at the moment of filling out the questionnaire, or solely not paying full attention to the question subject and completing the survey negligently, which is being observed as a very common response behavior in filling out questionnaires (questback 2019), (stieger and reips 2010). there are numerous factors for negligence in filling out the surveys, e.g., rush, inattentiveness, carelessness, and these factors can not be eliminated completely, however, the percentage of honest and credible responses can be substantially increased by certain mechanisms in the design and the content of the survey (kelley et al. 2003). the survey generated by our team was prepared with full recognition of risks related respondents assessed indoor air quality as neutral on the scale from 1 to 7. the low satisfaction rate is attributed to inadequate air exchange and overheating in the warm season, when the heat gains due to solar radiation intensify and the daytime temperature exceeds 20oc (primarily may – september). reducing temperature in certain premises during the warm season would ensure higher iec satisfaction level among the personnel, as well as offer energy savings (if the overheating period overlaps with the heating season). the results of the survey are outlined in fig. 5 and 6. figure 5. respondents’ satisfaction level with the room temperature (left) and indoor air quality (right). figure 6. respondents’ satisfaction level with the indoor air humidity and indoor temperature. the analysis of the survey illustrates the issue of indoor comfort in the studied building. many respondents gave negative ratings on indoor air temperature, relative humidity, and air quality; however, the largest percentage expressed that they are neither satisfied nor dissatisfied with the iaq parameters, giving the score of 4. this may also be linked to some respondents being comfortable at the moment of filling out the questionnaire, or solely not paying full attention to the question subject and completing the survey negligently, which is being observed as a very common response behavior in filling out questionnaires (questback 2019), (stieger and reips 2010). there are numerous factors for negligence in filling out the surveys, e.g., rush, inattentiveness, carelessness, and these factors can not be eliminated completely, however, the percentage of honest and credible responses can be substantially increased by certain mechanisms in the design and the content of the survey (kelley et al. 2003). the survey generated by our team was prepared with full recognition of risks related respondents assessed indoor air quality as neutral on the scale from 1 to 7. the low satisfaction rate is attributed to inadequate air exchange and overheating in the warm season, when the heat gains due to solar radiation intensify and the daytime temperature exceeds 20oc (primarily may – september). reducing temperature in certain premises during the warm season would ensure higher iec satisfaction level among the personnel, as well as offer energy savings (if the overheating period overlaps with the heating season). the results of the survey are outlined in fig. 5 and 6. figure 5. respondents’ satisfaction level with the room temperature (left) and indoor air quality (right). figure 6. respondents’ satisfaction level with the indoor air humidity and indoor temperature. the analysis of the survey illustrates the issue of indoor comfort in the studied building. many respondents gave negative ratings on indoor air temperature, relative humidity, and air quality; however, the largest percentage expressed that they are neither satisfied nor dissatisfied with the iaq parameters, giving the score of 4. this may also be linked to some respondents being comfortable at the moment of filling out the questionnaire, or solely not paying full attention to the question subject and completing the survey negligently, which is being observed as a very common response behavior in filling out questionnaires (questback 2019), (stieger and reips 2010). there are numerous factors for negligence in filling out the surveys, e.g., rush, inattentiveness, carelessness, and these factors can not be eliminated completely, however, the percentage of honest and credible responses can be substantially increased by certain mechanisms in the design and the content of the survey (kelley et al. 2003). the survey generated by our team was prepared with full recognition of risks related daytime temperature exceeds 20oc (primarily may – september). reducing temperature in certain premises during the warm season would ensure higher iec satisfaction level among the personnel, as well as offer energy savings (if the overheating period overlaps with the heating season). the results of the survey are outlined in fig. 5 and 6. the analysis of the survey illustrates the issue of indoor comfort in the studied building. many respondents gave negative ratings on indoor air temperature, relative humidity, and air quality; however, the largest percentage expressed that they are neither satisfied nor dissatisfied with the iaq parameters, giving the score of 4. this may also be linked to some respondents being comfortable at the moment of filling out the questionnaire, or solely not paying full attention to the question subject and completing the survey negligently, which is being observed as a very common response behavior in filling out questionnaires (questback 2019), (stieger and reips 2010). there are numerous factors for negligence in filling out the surveys, e.g., rush, inattentiveness, carelessness, and these factors can not be eliminated completely, however, the percentage of honest and credible responses can be substantially increased by certain mechanisms in the design and the content of the survey (kelley et al. 2003). the survey generated by our team was prepared with full recognition of risks related to humans’ response behavior and therefore it was carefully reviewed and adjusted before final dissemination to the personnel. 103 journal of sustainable architecture and civil engineering 2020/2/27 when asked to specify the source(-es) of dissatisfaction, most respondents indicated the lack of control over room temperature and excessive heat from direct sunlight (fig. 7) as the main flaws. these two factors can be linked together, suggesting that the building is not equipped neither with temperature sensors and automated ventilation control to account for overheating, nor with the manually adjustable thermostats, which leads to overtemperature if the direct sunlight penetration is not controlled by window blinds. many respondents also pointed out the unpleasant odors and draft from windows as the cause of their dissatisfaction. these factors also indicate on poor tightness of the building envelope, as well as the lack or improper operation of ventilation system. fig. 7 sources of dissatisfaction with the ieq to humans’ response behavior and therefore it was carefully reviewed and adjusted before final dissemination to the personnel. when asked to specify the source(-es) of dissatisfaction, most respondents indicated the lack of control over room temperature and excessive heat from direct sunlight (fig. 7) as the main flaws. these two factors can be linked together, suggesting that the building is not equipped neither with temperature sensors and automated ventilation control to account for overheating, nor with the manually adjustable thermostats, which leads to overtemperature if the direct sunlight penetration is not controlled by window blinds. many respondents also pointed out the unpleasant odors and draft from windows as the cause of their dissatisfaction. these factors also indicate on poor tightness of the building envelope, as well as the lack or improper operation of ventilation system. figure 7. sources of dissatisfaction with the ieq. the technical inspection of the building showed that the mechanical ventilation system may not have been balanced properly, and the ahu equipment does not meet the capacity demand to cool down premised during intense sunlight hours and warm season. the existing ventilation system needs a series of upgrades, including the installation of a more powerful ahu, installation of room temperature sensors and vav dampers, as well as proper system balancing. also, installing manual or automated external blinds coupled with solar sensors would greatly reduce the risk of overheating and glare during intense sunlight hours. human comfort zone and iaq measurements fig. 8 represents the iaq measurements conducted in the building throughout the timeframe of the survey that was occurring during the 7 days period. as it is seen in the graph (fig. 9.), the indoor temperature fluctuated between 21 and 24 oc, which is slightly above the average human comfort temperature stipulated in csa z412-17 “office ergonomics – an application standard for workplace ergonomics” (anon 2012). according to the standard, in the winter conditions the optimum temperature in offices is 22°c with an acceptable range of 2023.5°c. latvian cab. reg. no. 359 “work safety requirements in workplaces” sets the optimum temperature range for category 2 workplaces (work related to medium activity, equivalent to metabolic activity of 2.0-3.0 met) between 16 and 23oc in wintertime (anon 2009), which reiterates that temperature increase over 23oc is simply not justified to meet satisfactory indoor climate. also, it is important to highlight, that the military personnel and the technical inspection of the building showed that the mechanical ventilation system may not have been balanced properly, and the ahu equipment does not meet the capacity demand to cool down premised during intense sunlight hours and warm season. the existing ventilation system needs a series of upgrades, including the installation of a more powerful ahu, installation of room temperature sensors and vav dampers, as well as proper system balancing. also, installing manual or automated external blinds coupled with solar sensors would greatly reduce the risk of overheating and glare during intense sunlight hours. human comfort zone and iaq measurements fig. 8 represents the iaq measurements conducted in the building throughout the timeframe of the survey that was occurring during the 7 days period. as it is seen in the graph (fig. 9), the indoor temperature fluctuated between 21 and 24 oc, which is slightly above the average human comfort temperature stipulated in csa z412-17 “office ergonomics – an application standard for workplace ergonomics” (anon 2012). according to the standard, in the winter conditions the optimum temperature in offices is 22°c with an acceptable range of 20-23.5°c. latvian cab. reg. no. 359 “work safety requirements in workplaces” sets the optimum temperature range for category 2 workplaces (work related to medium activity, equivalent to metabolic activity of 2.0-3.0 met) between 16 and 23oc in wintertime (anon 2009), which reiterates that temperature increase over 23oc is simply not justified to meet satisfactory indoor climate. also, it is important to highlight, that the military personnel and trainees wear uniform when on their duties, therefore to assess the comfort perception of the military personnel in administrative buildings it is important to take into account clothing specifics with regards to their thermal insulation (clo) (goldman and kampmann 2007). national armed forces of the republic of latvia use standard military personnel uniforms with clo value of 1.4, which adds to the comfort temperature sensation and would require slightly lower temperature range than stipujournal of sustainable architecture and civil engineering 2020/2/27 104 lated in the norms. using the online calculator for assessing human thermal comfort based on indoor conditions, occupant metabolic rate and clothing level that was developed at uc berkeley (hoyt et al. 2013) (fig. 8) it can be easily and quickly verified that personnel wearing thicker than normal clothing layers would require substantially lower indoor temperature (20oc instead of 25oc as per the example below) to fulfill their indoor comfort criteria. according to the temperature and humidity graphs (fig. 9), throughout the weekdays the indoor temperature is maintained at 21oc, which given the personnel activity level (met) and thermal insulation (clo) may be perceived as 23-24oc, resulting in negative feedback with regards to not having control over room temperature. this discomfort only intensifies during sunny days when the heat from direct sunlight penetrates into the premises. the weekend temperature (during non-occupancy) is substantially higher (between 22.0 and 24.5oc), which may be related to the fact that the mechanical ventilation system have been turned off and/or that windows have been kept closed for the weekend. the relative humidity ranges over a quite wide span (from 13% to fig. 8 human comfort zone diagram (hoyt et al. 2013) b) t = 20oc, rh = 50%, clo = 1.4 trainees wear uniform when on their duties, therefore to assess the comfort perception of the military personnel in administrative buildings it is important to take into account clothing specifics with regards to their thermal insulation (clo) (goldman and kampmann 2007). national armed forces of the republic of latvia use standard military personnel uniforms with clo value of 1.4, which adds to the comfort temperature sensation and would require slightly lower temperature range than stipulated in the norms. using the online calculator for assessing human thermal comfort based on indoor conditions, occupant metabolic rate and clothing level that was developed at uc berkeley (hoyt et al. 2013) (fig. 8.) it can be easily and quickly verified that personnel wearing thicker than normal clothing layers would require substantially lower indoor temperature (20oc instead of 25oc as per the example below) to fulfill their indoor comfort criteria. figure 8. human comfort zone diagram (hoyt et al. 2013): a) left: t = 25oc, rh = 50%, clo = 1.4; b) right: t = 20oc, rh = 50%, clo = 1.4. according to the temperature and humidity graphs (fig. 9), throughout the weekdays the indoor temperature is maintained at 21oc, which given the personnel activity level (met) and thermal insulation (clo) may be perceived as 23-24oc, resulting in negative feedback with regards to not having control over room temperature. this discomfort only intensifies during sunny days when the heat from direct sunlight penetrates into the premises. the weekend temperature (during non-occupancy) is substantially higher (between 22.0 and 24.5oc), which may be related to the fact that the mechanical ventilation system have been turned off and/or that windows have been kept closed for the weekend. the relative humidity ranges over a quite wide span (from 13% to 41%), with the average humidity on the weekdays – 38.6%, and on the weekend – 20.6%. the recommended relative humidity according to the cab. reg. no. 359 in workspaces is 30-70% (anon 2009). the relative humidity values on the weekend are below the recommended range, while during the weekdays it lies within the recommended range yet converging to the bottom threshold. the relative humidity between 20 and 30% does not cause any direct health issues, and although a long-term exposure to humidity below 25% may cause irritation and headache, there is little experimental evidence to indicate that the mucous membranes of healthy individuals are adversely affected by low relative humidity even after prolonged exposure (arundel et al. 1986). trainees wear uniform when on their duties, therefore to assess the comfort perception of the military personnel in administrative buildings it is important to take into account clothing specifics with regards to their thermal insulation (clo) (goldman and kampmann 2007). national armed forces of the republic of latvia use standard military personnel uniforms with clo value of 1.4, which adds to the comfort temperature sensation and would require slightly lower temperature range than stipulated in the norms. using the online calculator for assessing human thermal comfort based on indoor conditions, occupant metabolic rate and clothing level that was developed at uc berkeley (hoyt et al. 2013) (fig. 8.) it can be easily and quickly verified that personnel wearing thicker than normal clothing layers would require substantially lower indoor temperature (20oc instead of 25oc as per the example below) to fulfill their indoor comfort criteria. figure 8. human comfort zone diagram (hoyt et al. 2013): a) left: t = 25oc, rh = 50%, clo = 1.4; b) right: t = 20oc, rh = 50%, clo = 1.4. according to the temperature and humidity graphs (fig. 9), throughout the weekdays the indoor temperature is maintained at 21oc, which given the personnel activity level (met) and thermal insulation (clo) may be perceived as 23-24oc, resulting in negative feedback with regards to not having control over room temperature. this discomfort only intensifies during sunny days when the heat from direct sunlight penetrates into the premises. the weekend temperature (during non-occupancy) is substantially higher (between 22.0 and 24.5oc), which may be related to the fact that the mechanical ventilation system have been turned off and/or that windows have been kept closed for the weekend. the relative humidity ranges over a quite wide span (from 13% to 41%), with the average humidity on the weekdays – 38.6%, and on the weekend – 20.6%. the recommended relative humidity according to the cab. reg. no. 359 in workspaces is 30-70% (anon 2009). the relative humidity values on the weekend are below the recommended range, while during the weekdays it lies within the recommended range yet converging to the bottom threshold. the relative humidity between 20 and 30% does not cause any direct health issues, and although a long-term exposure to humidity below 25% may cause irritation and headache, there is little experimental evidence to indicate that the mucous membranes of healthy individuals are adversely affected by low relative humidity even after prolonged exposure (arundel et al. 1986). figure 9. measured iaq parameters in an administrative military personnel facility. co2 concentration in non-renovated post soviet union buildings (refer to the introduction for detailed description) is usually lower than in recently constructed buildings, due to lower building envelope tightness (especially along window frames) which results in excessive outdoor air infiltration. as such, the co2 concentration in the investigated building did not present any concern and was in the range of 400-800 ppm on the weekdays, and in the range of 400-600 on the weekend, which is attributed to occupant presence and absence periods. ashrae standard 62.1-2016 ventilation for acceptable indoor air quality recommendations define that indoor co2 concentration level should be kept below 1000 ppm (ansi/ashrae standard 62.1 2016). on the other hand, even co2 concentration as high as 5000 ppm although co2 concentration is not a reliable indicator of overall building air quality, the excessive co2 concentration (>1200 ppm) clearly suggests that there is not enough fresh air supply and sufficient air exchange in the premise. conclusions the energy efficiency requirements for unclassified buildings are not defined in the current regulatory building codes, as this building category accounts for less than 2% of total building stock. unclassified buildings feature variety of structures with broad scope of energy performance criteria and stringent safety (and security) requirements. moreover, according to the worldwide practice, energy efficiency upgrades in this building category has not been at the agenda for national governments and stakeholders. nevertheless, the issue of poor energy conservation and management in those buildings should be addressed in future – by enhancing building envelope (proper thermal insulation, reducing thermal bridges, improving air tightness) and upgrading mechanical systems (energy saving lighting equipment, efficient mechanical ventilation, duct tightness, heat recovery). as a matter of fact, according to a recent study, a typical façade retrofitting package can generate 30% reduction in thermal figure 9. measured iaq parameters in an administrative military personnel facility. co2 concentration in non-renovated post soviet union buildings (refer to the introduction for detailed description) is usually lower than in recently constructed buildings, due to lower building envelope tightness (especially along window frames) which results in excessive outdoor air infiltration. as such, the co2 concentration in the investigated building did not present any concern and was in the range of 400-800 ppm on the weekdays, and in the range of 400-600 on the weekend, which is attributed to occupant presence and absence periods. ashrae standard 62.1-2016 ventilation for acceptable indoor air quality recommendations define that indoor co2 concentration level should be kept below 1000 ppm (ansi/ashrae standard 62.1 2016). on the other hand, even co2 concentration as high as 5000 ppm although co2 concentration is not a reliable indicator of overall building air quality, the excessive co2 concentration (>1200 ppm) clearly suggests that there is not enough fresh air supply and sufficient air exchange in the premise. conclusions the energy efficiency requirements for unclassified buildings are not defined in the current regulatory building codes, as this building category accounts for less than 2% of total building stock. unclassified buildings feature variety of structures with broad scope of energy performance criteria and stringent safety (and security) requirements. moreover, according to the worldwide practice, energy efficiency upgrades in this building category has not been at the agenda for national governments and stakeholders. nevertheless, the issue of poor energy conservation and management in those buildings should be addressed in future – by enhancing building envelope (proper thermal insulation, reducing thermal bridges, improving air tightness) and upgrading mechanical systems (energy saving lighting equipment, efficient mechanical ventilation, duct tightness, heat recovery). as a matter of fact, according to a recent study, a typical façade retrofitting package can generate 30% reduction in thermal fig. 9 measured iaq parameters in an administrative military personnel facility 41%), with the average humidity on the weekdays – 38.6%, and on the weekend – 20.6%. the recommended relative humidity according to the cab. reg. no. 359 in workspaces is 30-70% (anon 2009). the relative humidity values on the weekend are below the recommended range, while during the weekdays it lies within the recommended range yet converging to the bottom threshold. the relative humidity between 20 and 30% does not cause any direct health issues, and although a longterm exposure to humidity below 25% may cause irritation and headache, there is little experimental evidence to indicate that the mucous membranes of healthy individuals are adversely affected by low relative humidity even after prolonged exposure (arundel et al. 1986). co2 concentration in non-renovated post soviet union buildings (refer to the introa) t = 25oc, rh = 50%, clo = 1.4 105 journal of sustainable architecture and civil engineering 2020/2/27 duction for detailed description) is usually lower than in recently constructed buildings, due to lower building envelope tightness (especially along window frames) which results in excessive outdoor air infiltration. as such, the co2 concentration in the investigated building did not present any concern and was in the range of 400-800 ppm on the weekdays, and in the range of 400-600 on the weekend, which is attributed to occupant presence and absence periods. ashrae standard 62.1-2016 ventilation for acceptable indoor air quality recommendations define that indoor co2 concentration level should be kept below 1000 ppm (ansi/ashrae standard 62.1 2016). on the other hand, even co2 concentration as high as 5000 ppm although co2 concentration is not a reliable indicator of overall building air quality, the excessive co2 concentration (>1200 ppm) clearly suggests that there is not enough fresh air supply and sufficient air exchange in the premise. conclusions the energy efficiency requirements for unclassified buildings are not defined in the current regulatory building codes, as this building category accounts for less than 2% of total building stock. unclassified buildings feature variety of structures with broad scope of energy performance criteria and stringent safety (and security) requirements. moreover, according to the worldwide practice, energy efficiency upgrades in this building category has not been at the agenda for national governments and stakeholders. nevertheless, the issue of poor energy conservation and management in those buildings should be addressed in future – by enhancing building envelope (proper thermal insulation, reducing thermal bridges, improving air tightness) and upgrading mechanical systems (energy saving lighting equipment, efficient mechanical ventilation, duct tightness, heat recovery). as a matter of fact, according to a recent study, a typical façade retrofitting package can generate 30% reduction in thermal energy consumption for space heating, while deep renovation measures (including mechanical ventilation system with heat recovery) could result in up to 86% savings. the study results of the analyzed cold period show that humidity and co2 level in an administrative military building remain within the comfort zone, given the relatively high permeability and infiltration degree of an external envelope. measured temperature during the occupancy days remains rather stable at 21oc, which lies within the comfort range. however, the survey results indicate on relatively high level of dissatisfaction with the indoor temperature in the building, that demonstrates a slight disagreement with the measured temperature values, suggesting the periodic and uncontrolled overheating in the premises. provided that military staff occupying the building are wearing uniforms that have a higher clo level than the outfit of an average office individual (1.4 clo and 1.0 clo, respectively), the comfort temperature range for military personnel differs from that specified in the existing building codes for public buildings. as such, the measured actual temperature of 21oc in the administrative office premises might be perceived by the majority of the occupants (particularly those wearing military uniform and having clothing ratio of 1.4) as relatively high, and thus, causing a sense of overheating. in line with the need for renovation of the majority of the existing unclassified buildings, a clear regulatory environment should be established with regards to the thermal comfort criteria in unclassified buildings to address the issue of inadequate temperature settings (for the majority of the occupants) and insufficient ventilation in such buildings. moreover, currently applied practices of designing new construction unclassified buildings have to be thoroughly reviewed, and separate regulatory requirements have to be developed for various types of new construction unclassified buildings (military barracks, administrative offices, training facilities etc.). this study contributes to the existing knowledge of the poor energy management and conservation in unclassified buildings by identifying gaps in iec, while addressing the energy performance of those buildings via occupant survey and indoor air quality measurements. authors acknowledge, that the relatively low number of respondents completing the survey may compromise the credibility of the study results. on the other hand, for the study related to injournal of sustainable architecture and civil engineering 2020/2/27 106 vestigating military facilities that involved onsite technical inspection and occupant survey, such response figure is fairly reasonable. given that military facilities are kept under enhanced security and the access to such buildings is only granted to authorized personnel, our team is proud to have managed pioneer a study that may eventually trigger continuous efforts in addressing the significance of energy performance not only in military facilities, but on a broader 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analysis of cross-country consumption patterns.“ energy policy 129:1156-67. 2019.https://doi.org/10.1016/j. enpol.2019.03.003 wang, lijuan, jungsoo kim, jing xiong, and haiguo yin. „optimal clothing insulation in naturally ventilated buildings.“ building and environment 154:200-210. 2019.https://doi.org/10.1016/j.buildenv.2019.03.029 wells, ellen m., matt berges, mandy metcalf, audrey kinsella, kimberly foreman, dorr g. dearborn, and stuart greenberg. „indoor air quality and occupant comfort in homes with deep versus conventional energy efficiency renovations.“ building and environment 93(p2):331-38. 2015.https://doi.org/10.1016/j. buildenv.2015.06.021 yüksek, izzet and tülay tikansak karadayi. „energy-efficient building design in the context of building life cycle.“ in energy efficient buildings. 2017. https://doi.org/10.5772/66670 about the authors aleksejs prozuments phd researcher, mg. sc. ing. riga technical university, faculty of civil engineering, institute of heat, gas and water technology main research area energy efficiency in buildings, healthy buildings. address 6b/6a kipsalas str, riga, latvia. tel. +371 2919 0871 e-mail: aleksejs.prozuments@rtu.lv anatolijs borodinecs professor, dr sc. ing. riga technical university, faculty of civil engineering, institute of heat, gas and water technology main research area energy efficiency in buildings, renewable energy sources. address 6b/6a kipsalas str, riga, latvia. tel.+371 2607 9655 e-mail: anatolijs.borodinecs@rtu.lv jurgis zemitis postdoctoral researcher, dr. sc. ing. riga technical university, faculty of civil engineering, institute of heat, gas and water technology main research area indoor air quality, heating & ventilation. address 6b/6a kipsalas str, riga, latvia. tel.+371 2836 9940 e-mail: jurgis.zemitis@rtu.lv this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 11 darnioji architektūra ir statyba 2013. no. 1(2) journal of sustainable architecture and civil engineering issn 2029–9990 buildings of performing arts in latvia’s modern movement agate eniņa* riga technical university, faculty of architecture and urban planning, āzenes street 16/20–420, lv-1048, riga, latvia. * corresponding author: e-mail: agate.enina@inbox.lv http://dx.doi.org/10.5755/j01.sace.1.2.2840 after wwii, the soviet iron curtain impeded sharing of knowledge between the baltic socialist republics and other european states. it was necessary to find roundabout ways of introducing the innovative-minded global spirit, combined with the local architectural traditions and the actual possibilities established already in the 1920s and the 1930s. the aim of the article is to recognize the cultural and historic significance of buildings of performing arts, i.e. concert halls, cinemas and theatres, and determine their role in the history of latvian architecture. in order to achieve this, it is necessary to evaluate architectural qualities of performing arts buildings both in the context of stylistic trends of the epoch and in the broader geographical context. uncertain understanding of the place of the latvian cultural heritage on a european level prompted an in-depth analysis of buildings of performing arts in latvia’s modern movement. keywords: cultural heritage, history, latvia’s architecture, performing arts, soviet period. 1. introduction after wwii, the soviet iron curtain impeded sharing of knowledge between the baltic socialist republics and other european states. it was necessary to find roundabout ways of introducing the innovative-minded global spirit, combined with the local architectural traditions and the actual possibilities established already in the 1920s and 1930s. during world war ii, several cities like jelgava and gulbene were almost leveled to the ground; the new principles of land management policy changed the traditional rural landscape. in the post-war period though, a number of significant public buildings, new housing estates, grand civil engineering structures and other buildings were constructed in latvia. today the soviet relics have become part of latvia’s scenery and their preservation and development should be a responsibility of new generations of architects and historians and the general public as well. it is quite important to perform the inventory of buildings of cultural establishments ascertaining their typology and stylistic features. it would allow defining more objectively the place of latvian architecture in the european context, and determining further guidelines for development of cultural heritage. the aim of the study is to make an inventory of buildings of performing arts and their stylistic and functional features, and analyzing an overall development process of various types of buildings in the second half of the 20th century, to determine how the prevailing stylistic trends in the world, having blended with the local building traditions, had influenced and defined the place of latvian architecture and cultural heritage in the european context. 2. methods several research methods have been applied. the study is based on the analysis of the architecture of performing arts buildings. basic information about the buildings has been collected, systematized and classified. a number of unpublished sources and archival materials have been discovered and a method of monographic and historical approach has been used. the buildings have been identified, surveyed and photographed, and a comparative visual analysis has been performed. 3. results in the late 1950s, when construction of large-scale residential districts began in the cities of latvia using prefabricated building constructions (krastiņš et al. 1998), the same degree of industrialisation was also applied to the architecture of public buildings. designing institutes developed several standard designs for movie theaters, rural clubs, community centers and other establishments. designing of the most significant public buildings received 12 wide coverage. numerous sketch design competitions were held, which fostered development of a talented generation of latvian architects. buildings of performing arts were constructed according to individual designs. until the early 1990s, architects’ contribution to modern movement was considerable, and its influence is still present today both in the capital city and in towns. the structural principle of the analytical part is typological. buildings of performing arts are divided in three typological groups – open air stages, which include summer concert halls, movie theatres and theatre buildings. some prominent personalities like architects modris ģelzis and marta staņa played a significant role in introduction of modernist traditions. one of the most wellknown public buildings outside riga is the summer concert hall in jūrmala (architects m. ģelzis and alberts vecsīlis, 1959–1960). the architects took into consideration the picturesque environment creating an open inner space in the wonderful landscape of seaside dunes. the successful setting in the environment allowed avoiding external walls that are usually necessary for acoustic needs. the surrounding dunes are used for relaxation and walks during intermissions. also today this place has still retained the sense of spatial continuity. in the early 1960s, light music had taken centre stage encompassing also art and cinema. in 1965, the popular and beloved composer raimonds pauls became manager of riga light music orchestra. in 1967, the joint concert of light music bands in liepāja on the stage “pūt vējiņi” (“blow, wind, blow”) was given the name “amber of liepāja”. it was attended by about 30,000 spectators (kreituse 2010). the stage “pūt vējiņi” in liepāja was designed in 1961. today, however, it is in a very poor condition and requires extensive modification for its further development. several proposals for transformation were submitted at the open sketch design competition which ended in 2011. all architects mostly used a considerate approach offering to retain the existing stage structure, preserving spatial qualities and a relation with the coastal scenery, creating a new roof construction (fig. 1 and fig. 2). fig. 1. a remodelling proposal for the concert garden “pūt vējiņi” in liepāja. “kokin idea” ltd, 2011 (reconstruction…, 2011) fig. 2. a remodelling proposal for the concert garden “pūt vējiņi” in liepāja. “mark arhitekti” ltd, 2010 (“mark arhitekti” ltd, 2010) the architecture of open-air stages of jūrmala and liepāja tended to retain the relation with the surrounding scenic environment. the main concept was based on transparency of massing and organic continuation of the scenery in the interior. their concepts seem to be inspired by the finnish architect alvar aalto and his humane treatment of landscape transformation. already in the pre-war period, the relationship between the traditions of local building craft and european architecture was quite close in latvia. in order to expand their knowledge, architects travelled around northern europe and visited also largest italian and german cities (kampe 1929). the iron curtain put paid to those trips, however, there were a number of magazines available in russian, which analyzed the works of alvar aalto, le corbusier, niemeyer and other world-renowned architects (современная архитектура 1964–1974, савицкий 1972). assimilation of the traditions of local schools of architecture and the latest trends in modern movement in the world most boldly manifested in several competition entries. the competition entry developed by architect marta staņa in 1968 for an open-air stage in jelgava (“mark arhitekti” ltd, 2009) illustrates the blending of deep-rooted folk traditions and aesthetic principles of modern movement into a single architectural image (fig. 3 and fig. 4). fig. 3. a competition entry for an open-air stage in jelgava, 1968. architect marta staņa. authors of visualisation “mark arhitekti” ltd, 2009 (“mark arhitekti” ltd, 2009) 13 fig. 4. a competition entry for an open-air stage in jelgava, 1968. architect marta staņa. authors of visualisation “mark arhitekti” ltd, 2009 (“mark arhitekti” ltd, 2009) aesthetic qualities of the exposed reinforced concrete structures of the open-air stage and juxtaposition of curves and straight lines bespeak the plastic forms used by le corbusier and niemeyer. the architect had avoided any decorations, using instead a technologically sophisticated structure within a proportionate and well-balanced composition. exposition of structures was a trendy feature. however, such bold ideas could not be implemented in the soviet union because of bureaucratic hurdles, and very often, like in this case, the ideas did not materialize. the design for one of the most well-known buildings in the soviet union, which was designed by latvian architects, was also selected as a result of a competition. in 1956, the state committee for cinematography organized a competition for an architectural solution of the panorama movie theater in riga. first prize was not awarded, but second prize was given to the design elaborated by architects oļģerts krauklis and daina dannenberga. the design was not implemented in latvia. however, after its exhibition in moscow, the movie theater was built in celinograd (now astana in kazakhstan). in 1962, krauklis and dannenberga worked on location in celinograd. according to the architect, it was a real “school of life” (dannenberga 2011) and its outcome was the movie theater with 2500 tiered seats. the building can be used not only for exhibition of films but also as a venue for congresses, conferences and concerts. the acoustic solution was developed by latvian architect alberts vecsīlis. perhaps the high quality of acoustics is the reason allowing using the movie theatre to the present day. the architecture of the building displays features of modern movement. huge expanses of glass alternate with sections of rendered walls. the building has a harmonious image and a clear center of the spatial composition. the ideas of open plan and modern movement rapidly spread in the mid-1960s. movies were acknowledged to be folk art, and movie theatres were built extensively. open design principles have been applied in construction of several movie theatres in the historic centre of riga, e.g. the movie theatre “palladium” and the movie theatre “pionieris”. fig. 5. the foyer of the movie theatre “pionieris”, architect juris pētersons, 1962 (foyer…, 2012) the construction of the movie theatre “palladium” was begun already in 1913. the round shaped auditorium was built in the courtyard of the “perpendicular” art nouveau apartment house (architects edgar friesendorff and otto lantzky, 1910). the existing structures at the back of the plot were remodelled in 1925 in remarkable style of art deco (architect pavils drejmanis). the movie theatre was renovated twice after the fires in 1957 (architects modris ģelzis and artūrs reinfelds) and in 1965 (architect ojārs dombrovskis), each time in up-to-date formal and spatial expression. “palladium” opened its doors again in 2011. it was renovated by an architect office “arhitekti argali” ltd. the auditorium’s powerful and elegantly balanced architecture is retained. nowadays it could seat more than 2000 visitors. in the architecture of the movie theatre “pionieris” (architect juris pētersons, 1962) an attempt has been made to create relative boundaries that would spatially organize the visitors but would not separate the interior spaces from the architectural saturation of the adjacent historic buildings and the greenery of esplanade – one of the central parks of riga – on the opposite side of the street (fig. 5). discussions about the implementation of modernist ideas in the relatively dense urban environment have been initiated in latvia several times. a glass parallelepiped of the new building of the movie theatre “spartaks” (architect marta staņa, 1967) creates a transparent curtain which covers from view the lavishly decorated portal of another movie theatre “splendid palace” (architect fridrihs skujiņš, 1923). perhaps the squalid surroundings, controversial conversion and inappropriate function (the building currently houses a casino) are the reasons preventing local inhabitants from enjoying the architectural qualities of the building. the architecture of the movie theatre seems to be inspired by the works of mies van der rohe who liked multiplication of one structural element. the result is a pure, geometric shape which emphasizes and highlights the basic values of modern movement – asceticism and simplicity (fig. 6). 14 fig. 6. the movie theatre “spartaks”, architect marta staņa, 1967. photography of 1970-ties (movie…, 2012) in ten years modern movement spread to the other cities of latvia as well. the building of the movie theater in daugavpils (architects oļģerts krauklis and maija skalberga, 1981) displays the principles of modern movement and the use of local building materials and building traditions established during the pre-war period (fig. 7 and fig. 10). having resemblance to the house of culture in helsinki, built in 1959 to the design by alvar aalto, the streamlined external contour of the building and a monumental brick wall highlight the expressiveness of the daugavpils movie theater (fig. 9). fig. 7. the movie theatre in daugavpils, architects oļģerts krauklis, m. skalberga, 1981 along with the development of cinema, latvian theatre had great success in the soviet union. the performances of the daile theatre on tour received much acclaim in moscow. fig. 8. a sketch of the daile theatre in riga including a prospective vision of a high-rise, architect marta staņa, 1960-ies fig. 9. house of culture in helsinki, architect alvar aalto, 1958 (krastiņš, 1992a) fig. 10. the movie theatre in daugavpils, architects oļģerts krauklis, m. skalberga, 1981 in 1959, the competition was held, where the design with the motto “1111” by marta staņa and tekla ieviņa won first prize being the best among 26 entries (banga 2012). the complicated designing and construction process lasted 17 years, and architects imants jākobsons and haralds kanders completed the project already after marta staņa’s death. the building of the daile theatre was part of the main urban planning axis of riga or development concept for brīvības iela, with its basic element being “a two-storey paviliontype building raised on pillars at a ground-floor height” (krastiņš 2010). to make the two-storey glass structure appear more effective it was intended to accentuate it with the towers. in the sketch drawn by marta staņa in the 1960s, next to the theatre building there is a high-rise, which was never built (fig. 8). fig. 11. the daile theatre in riga, architects marta staņa, imants jākobsons, haralds kanders, 1959–1976. photography of 1970-ties (daile…, 2012) 15 fig. 12. finlandia concert hall in helsinki, architect alvar aalto, 1962–1975 (krastiņš, 1992b) although in the course of designing the massing of the daile theatre was altered several times, the completed building generally reflects the concept of the original competition entry. a two-storey glass foyer with an integrated auditorium and stage is complemented with a strong dynamic accent. it is enlivened by a relief boasting a dramatic motif of flames by sculptor ojārs feldbergs. the flame motif, the widely used logotype of the theatre, was successfully interpreted by the sculptor, becoming the impressive part of the architectural composition. the theatre building is well perceived from several adjacent streets. its peculiar massing provides interesting views from all sides – the main entrance, the actors’ entrance and the nearby public garden what is very important for such significant public objects. the architecture of the daile theatre relies heavily on reinforced concrete structures and finish materials. concrete columns stand exposed in the interior creating a contrast with the large expanses of glass. the finish of exterior spaces creates a harmonious overall image through the application of reinforced concrete, brown textured bricks, dark anodized aluminium and granite. the architecture of the daile theatre bespeaks national self-confidence through excellence in performing arts and modern movement, which marta staņa explored studying at the faculty of architecture of latvian university under the guidance of ernests štālbergs. she was the first woman who graduated the faculty after the war in 1945. like many other talented architects, in 1951 lecturer marta staņa had to leave the university as “an unwanted follower of rational architecture” (banga 2012). however, difficulties only strengthened architect’s character and today her works can be compared to alvar aalto’s great masterpieces. like finlandia concert hall and convention center in helsinki (weston, 1995) built between 1962 and 1975, the daile theatre is the landmark of the capital city and a unique example of modern movement (fig. 11 and fig. 12). after world war ii, a strong school of architecture with distinctive national features and accents had formed in latvia. the singularity revealed itself directly only occasionally, most often it was indirect and defined by the nature of the materials and structures used, the relation to cultural traditions and folk art, the surrounding environment etc. at the same time architecture became international and it was determined by several factors, namely, the synthesis of values and mass production requirements, standardization of designs and emphasis on functionality at the expense of aesthetic qualities. therefore, the architecture of soviet latvia can be compared to the works of those european architects which reflected a similar understanding of values. quite often the neglected area around the buildings of performing arts hinders perception and understanding of modernist architecture. a larger attention should be paid to the lack of quality of the exterior spaces surrounding the buildings. it is also necessary to explain the ideological role of monumental and decorative arts, the importance of decorative sculpture in organization of interior and exterior spaces and the need of street furniture in the public open space. sometimes as a result of present-day conversions the works of fine arts are lost. a particular attention should be paid to the problems of regeneration of the architecture of the performing arts buildings of the soviet period. 4. discussion several issues arise in the context of preservation and development of the soviet heritage: ▪ the prevailing psychological and political prejudices hinder an objective assessment of the buildings constructed during the respective period. for quite a long time, the architecture of the respective period was associated with the worst manifestations of the regime; therefore the public was not prepared to accept the architecture of these buildings as part of unique cultural heritage. ▪ the role of performing arts buildings constructed during the soviet period in the world cultural heritage of the respective period has not been defined. ▪ today the evaluation of the legacy of the soviet period changes and the attention is paid to individual architects and their creative achievements. ▪ the quality of construction is not always satisfactory and structures are not always durable. ▪ no attention was paid to accessibility of buildings because the soviet statement was “there are no disabled people at all”. it is our task today to find a solution to this problem. in riga, these problems concern several conceptually open design examples, e.g. the state philharmonic (reconstructed after the fire in 1963 by architects modris ģelzis, vera savisko) and the daile theatre. ▪ considering the fact that the buildings are relatively new (not older than 50 years), they are not regarded as a cultural heritage value. nowadays exceptions exist. in 1998 the daile theatre was included into the list of the protected monuments. 5. conclusions there is still an issue of the role of architecture of cultural and entertainment buildings in the context of the world cultural heritage of the respective period. significant buildings of performing arts were built in latvia at the same 16 time when similar buildings appeared in the other european countries. their architectural quality and aesthetic richness is equivalent. this allows treating them as excellent examples of modern movement which need to be preserved and promoted at the european level. focusing on certain architects and their works would be one of the possible ways how to preserve and develop properly architectural heritage of the soviet period and raise awareness of its significance, thus also treating architecture as art. there already have been several retrospective exhibitions which focused on architects modris ģelzis and marta staņa and explored possibilities for conversion of several buildings of the soviet period. the values of modern movement are recognized at a very slow pace in latvia. in future the architecture of modern movement should be divided into several stylistic groups. even though some attempts of stylistic classification of modern movement in latvia already exist, those were felt into neglect. nowadays stylistic varieties can be distinguished taking into account the general evolution of the style blending with local traditions, e.g. regional cubism and minimalism, which would include aesthetics of “boxes”, and plastic humanism, which would refer to modernist attempts to blend with the surrounding environment. similarly, characteristic approaches of certain architects can be distinguished, e.g. avant-garde of marta staņa, regionalism of modris ģelzis or functionalism of oļgerts krauklis etc. thus, it would be easier for the local community to identify them as part of their national architectural and cultural heritage. acknowledgment this work has been supported by the european social fund within the project «support for the implementation of doctoral studies at riga technical university». references banga v. 2012. marta staņa un dailes teātra kolīzijas. in: ābele, k., personība mākslas procesos, neputns, rīga, 2012, 198–212. 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[kreituse, i. 2010. yesteryear latvia 1945–1990. zvaigzne abs, riga, 2009, 134–153.] kampe p. 1929. aleksandrs vanags 1873.–1919. kā cilvēks un kā celtnieks. j. pētersons un biedri, rīga, 1929, 20 lpp. [kampe, p. 1929. aleksandrs vanags 1873.–1919. like a person and like a builder. j. pētersons associate, riga, 1929, 20 p.] “mark arhitekti” ltd, 2009. a competition entry for an open-air stage in jelgava, 1968, picture. material from the archives of„mark arhitekti” ltd. “mark arhitekti” ltd, 2010. a remodelling proposal for the concert garden “pūt vējiņi” in liepāja, picture. material from the archives of„mark arhitekti” ltd. movie theatre “saprtaks”. available at: http://www.citariga.lv/ lat/rigas-apskates-vietas/pirmas-brivvalsts-laiks/kino-riga/ (accessed 20 april 2011). reconstruction proposal for the concert garden “pūt vējiņi” in liepāja. available at: http://www.a4d.lv/lv/projekti/putvejini-konkursa-uzvaretaju-projekts/ (accessed 20 april 2011). sketch by architect m. staņa of 1960-ies of the daile theatre in riga including a prospective vision of a high-rise, picture. material from the archives of architect daina dannenberga. weston, r., 1995, alvar aalto. phaidon press limited, london, 1995, 240 p. савицкий ю. ю, 1972. архитектура капиталических стран. стройиздат, москва, 134 с. [savickij, y.y, the architecture of the capitalistic countries. 1972. stroyizdat, moscow, 134 p.] современная архитектура, 1964–1974. издателъство литературы по строителъству, москва, 1964–1974. [contemporary architecture, 1964–1974. publishing house of construction, moscow, 1964–1974.] received 2012 11 02 accepted after revision 2013 02 22 agate eniņa – phd student at riga technical university, faculty of architecture and urban planning. main research areas: the architecture of cultural and educational establishments in latvia. address: āzenes street 16/20–420, lv-1048, riga, latvia. tel.: +371 283 80477 e-mail: agate.enina@inbox.lv journal of sustainable architecture and civil engineering 2020/2/27 32 corresponding author: etousi@uniwa.gr interaction among social, cultural and environmental factors in vernacular settlements. the case of korogonianika, in lakonia, greece received 2020/06/02 accepted after revision 2020/10/04 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 32-39 doi 10.5755/j01.sace.27.2.27060 interaction among social, cultural and environmental factors in vernacular settlements. the case of korogonianika, in lakonia, greece jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.27060 evgenia tousi architect-urban and regional planner ntua, adjunct lecturer at the school of interior architecture, university of west attica, greece according to literature, the term vernacular architecture describes the type of architecture that is aligned with local environmental, socio-economic and cultural circumstances, constructed during the pre-industrial era (petronotis, 1980). in most of the cases, vernacular architecture involves structures made by local residents. the usage of local materials and the adjustment to the local climate conditions are the two main factors that contribute to the sustainability of vernacular settlements (lejeune,2010). in most of the cases, vernacular settlements reflect an ongoing interaction among socio-economic, cultural and environmental factors. the selected case study, a village in the prefecture of eastern mani, belongs to the regional administrative area of peloponnese. it could be described as a typical case study of the vernacular settlements of southern greece. this peninsula includes 40 dispersed vernacular settlements protected by national legislation law φεκ 594/δ/78. this law enforces specific morphological rules and regulations. archaeological findings in the area reveal settlements that date back to the paleolithic and neolithic era (chapin, et.al. 2014). moreover, pertinent literature stresses the the article presents the main findings of a research focusing on the unique attributes of vernacular architectural heritage of southern greece. the analysis of the interaction between social, cultural and environmental factors, is based on literature review and field work. this interaction is portrayed through the use of a pilot case study, the village korogonianika which is a typical and representative example for all vernacular settlements of eastern mani. field work involves original cartographic depiction, photos, drawings as well as participant observation and interviews. keywords: greek vernacular settlements, environmental assessment, socio-spatial interaction, sustainability. introduction 33 journal of sustainable architecture and civil engineering 2020/2/27 nodal role of the area during the mycenaean era and the bronze age (cavanagh et.al., 2009). findings around 330 a.d. give prominence to the correlation between spatial and socio-economic parameters. thus, the production of space reflects not only the principles of an introverted local community but also the limitations of the natural surroundings (saitas, 2001). the residential patterns met at this early stage of organized settlements are based on local resources and materials as well as small scale socio-spatial networks. in particular, the rough, barren and anhydrous natural scenery determined the production of space and the social physiognomy of the area. the precarious living conditions because of the pirates’ incursions combined with the lack of natural resources, led to the creation of armed patriarchal clans as the basic pattern of socio-spatial structure in the area (ibid). these clans struggled for survival and independence. the rigid codex of principles that affected the organization of vernacular settlements in mani has been documented since the period 330-1453 a.d. (ibid). the christianization procedure of 10th -12th century and the period of frankish occupation (12491262) contributed to the formation of the cultural identity of the area. in particular, most of the vernacular settlements of the area constructed between the years 1263-1453, had been established by members of the despotate of mystras, a semi-autonomous province of the byzantine empire, flourishing between 14th and 15th century a.d. most of them kept the name of the prominent member of the despotate of mystras that establish them, as in the case of korogonianika (village of korogona, koutsilieris, 1993). despite the slight differences between northern and southern vernacular settlements of mani, there are common spatial and social patterns that characterize the construction of buildings, the spatial organization of each settlement and the materials used. this research explores, through the pilot case study, the interaction among socio-economic, cultural and environmental factors. the article attempts to provide interpretations for the physiognomy of the settlement as a whole and the type of buildings met in the area. methods the research comprises field work and literature review on the issue of vernacular settlements in the area of study. the author has visited numerous vernacular settlements in mani, lakonia with the view to organize their main features as far as environmental and socio-economic factors are concerned, focusing on their interaction. furthermore, the author conducted participant observation in the selected pilot case study, the village of korogonianika. the author studied the socio-spatial patterns of the contemporary inhabitants during the summer period and collected information, emphasizing on the use of buildings during the winter period. the author tried to interpret the contemporary physiognomy of the village as far as its location and spatial organization is concerned, as well as the underlying reasons for the construction of the specific architectural forms met in the village. observation and cartographic depiction combined with literature review, offered useful information about the forms and structures. interviews with the owners of the vernacular houses were necessary so as to collect information about the current use of the houses. qualitative research is based on purposive sampling, which is organized in the context of pre-selected criteria, relevant to particular research questions. fifteen owners took part in the research. the research started in 2015 during author’s attendance in the post-graduate program “environmental design of cities and buildings” at hellenic open university and was enriched and updated during 2019. field work includes surveying and original cartographic depiction of the selected case study, original architectural drawings of the main housing types and semi-structured interviews with residents. results and discussion spatial expressions of socio-economic and cultural factors the village of korogonianika, as the majority of vernacular settlements in mani, could be described as an undivided unit consisting of the main core and its’ extensions. according to national census data of the year 1856, the wider area of lagia district, where the village korogonianika belongs, journal of sustainable architecture and civil engineering 2020/2/27 34 had 1776 inhabitants. the population rate was on the increase until the mid-20th century. after the world war ii and the civil war, the majority of the inhabitants of the wider area, migrated to urban areas, mostly in the urban agglomeration of athens -piraeus (leontidou, 2001). since then, there have been recorded only a few permanent citizens. census data of 2001, present only 29 permanent citizens while field work has revealed that today there are only 4 permanent citizens. the village has 32 building complexes. fifteen of them are abandoned and fifteen of them are occupied only during the summer period. only two houses are occupied during the whole year. today, the majority of vernacular settlements of eastern mani, have only few permanent residents. all the constructions had defensive character in order to avoid intruders. this character was expressed through structural elements on the outer side of each building. some examples are the niche-standpoints and the loopholes in the wall. another interesting architectural feature is a type of special construction that could be used from the inside so as to pour hot water or oil on the enemies. another attribute of the vernacular settlements of mani, is the proximity of each housing unit to the other. this is observed only for residences belonging to members of the same clan, as recorded during field work in the village korogonianika (see map 1). the ulterior motive was to found shielding enclaves that could protect the clan in case of an invasion. according to field work the settlement took its complete form during the 19th century. korogonianika had been gradually expanding, keeping as a point of reference bofos’ tower (see map 1). it is until today the only highrise structure of the village (fig.2). athens -piraeus (leontidou, 2001). since then, there have been recorded only a few permanent citizens. census data of 2001, present only 29 permanent citizens while field work has revealed that today there are only 4 permanent citizens. the village has 32 building complexes. fifteen of them are abandoned and fifteen of them are occupied only during the summer period. only two houses are occupied during the whole year. today, the majority of vernacular settlements of eastern mani, have only few permanent residents. all the constructions had defensive character in order to avoid intruders. this character was expressed through structural elements on the outer side of each building. some examples are the niche-standpoints and the loopholes in the wall. another interesting architectural feature is a type of special construction that could be used from the inside so as to pour hot water or oil on the enemies. another attribute of the vernacular settlements of mani, is the proximity of each housing unit to the other. this is observed only for residences belonging to members of the same clan, as recorded during field work in the village korogonianika (see map 1). the ulterior motive was to found shielding enclaves that could protect the clan in case of an invasion. according to field work the settlement took its complete form during the 19th century. korogonianika had been gradually expanding, keeping as a point of reference bofos’ tower (see map 1). it is until today the only high-rise structure of the village (fig.2). map 1: the main core of the vernacular settlement and the two phases of expansion, bofo’s tower within the circle, field work, author’s work. fig.2: the southern side of the settlement of korogonianika, author’s photograph 2019. on the right is the tower that belongs to bofos’ family athens -piraeus (leontidou, 2001). since then, there have been recorded only a few permanent citizens. census data of 2001, present only 29 permanent citizens while field work has revealed that today there are only 4 permanent citizens. the village has 32 building complexes. fifteen of them are abandoned and fifteen of them are occupied only during the summer period. only two houses are occupied during the whole year. today, the majority of vernacular settlements of eastern mani, have only few permanent residents. all the constructions had defensive character in order to avoid intruders. this character was expressed through structural elements on the outer side of each building. some examples are the niche-standpoints and the loopholes in the wall. another interesting architectural feature is a type of special construction that could be used from the inside so as to pour hot water or oil on the enemies. another attribute of the vernacular settlements of mani, is the proximity of each housing unit to the other. this is observed only for residences belonging to members of the same clan, as recorded during field work in the village korogonianika (see map 1). the ulterior motive was to found shielding enclaves that could protect the clan in case of an invasion. according to field work the settlement took its complete form during the 19th century. korogonianika had been gradually expanding, keeping as a point of reference bofos’ tower (see map 1). it is until today the only high-rise structure of the village (fig.2). map 1: the main core of the vernacular settlement and the two phases of expansion, bofo’s tower within the circle, field work, author’s work. fig.2: the southern side of the settlement of korogonianika, author’s photograph 2019. on the right is the tower that belongs to bofos’ family map 1 the main core of the vernacular settlement and the two phases of expansion, bofo’s tower within the circle, field work, author’s work fig. 2 the southern side of the settlement of korogonianika, author’s photograph 2019. on the right is the tower that belongs to bofos’ family 35 journal of sustainable architecture and civil engineering 2020/2/27 this difference among constructions reflects discrepancies on social level. taking into account local cultural values, male-ruled, blood related clans were supposed to be powerful. they had the privilege to build high rise stone-made buildings, while all the others had been forced to keep a low height for their constructions. as a result, two main types of architectural synthesis are observed in mani’s vernacular agglomerations, as in the case of korogonianika. the first type is the rectangle-shaped tower (fig.3) and the other includes ground floor constructions with mezzanine in γlike shape (fig.4). transoms are rather low in all constructions, at about 1.5 meters as measured from the upper side of the floor. this short height of doors is owed to the defensive character of the house. since it did not facilitate a convenient entrance, it was considered to be a suitable strategy so as to repel invaders, as stated by the owners of the houses during the interviews. nuclear families and extended families with plenty of sons and grad-sons were allowed to use higher quality materials for the construction of their houses (kassis, 1980). privileged members of the patriarchic clans, forced families with daughters to use lower quality materials. this fact made the constructions vulnerable and easy to demolish. this issue could be perceived as an explicit spatial depiction of gender discrimination (ibid). fig. 3, 4: 3d view of bofos’ tower and γ-shape plan of a ground floor construction. the two typical housing types met in the village, author’s drawings, field work in any case, all the constructions and land properties were bestowed only to the male descendants. as for the housing facilities, all houses high rise or not, have until today tanks so as to store rainwater for household use. field work has revealed that the village was connected to the national electricity supply network in 1987. the connection to the national fixed telecommunication network was not fulfilled before the mid-90s. in account of all these, all houses had until recently poor facilities. ii. environmental assessment a. location and spatial organization of the settlement apart from the socio-economic and cultural factors, environmental parameters played a predominant role in the production of living space. basic elements of the natural environment as the mountain range of taygetos transfuse semi-mountainous characteristics to the majority of the vernacular settlements of the area of mani, as in the case of korogonianika. the length of the mountain range is 75 km and the width varies between 10 and 20 km., its height varies from 300 to 1214 m. there is also a plateau where the selected case study is located, at about fig. 3, 4 3d view of bofos’ tower and γ-shape plan of a ground floor construction. the two typical housing types met in the village, author’s drawings, field work this difference among constructions reflects discrepancies on social level. taking into account local cultural values, male-ruled, blood related clans were supposed to be powerful. they had the privilege to build high rise stone-made buildings, while all the others had been forced to keep a low height for their constructions. as a result, two main types of architectural synthesis are observed in mani’s vernacular agglomerations, as in the case of korogonianika. the first type is the rectangle-shaped tower (fig.3) and the other includes ground floor constructions with mezzanine in γlike shape (fig.4). transoms are rather low in all constructions, at about 1.5 meters as measured from the upper side of the floor. this short height of doors is owed to the defensive character of the house. since it did not facilitate a convenient entrance, it was considered to be a suitable strategy so as to repel invaders, as stated by the owners of the houses during the interviews. nuclear families and extended families with plenty of sons and grad-sons were allowed to use higher quality materials for the construction of their houses (kassis, 1980). privileged members of the patriarchic clans, forced families with daughters to use lower quality materials. this fact made the constructions vulnerable and easy to demolish. this issue could be perceived as an explicit spatial depiction of gender discrimination (ibid). this difference among constructions reflects discrepancies on social level. taking into account local cultural values, male-ruled, blood related clans were supposed to be powerful. they had the privilege to build high rise stone-made buildings, while all the others had been forced to keep a low height for their constructions. as a result, two main types of architectural synthesis are observed in mani’s vernacular agglomerations, as in the case of korogonianika. the first type is the rectangle-shaped tower (fig.3) and the other includes ground floor constructions with mezzanine in γlike shape (fig.4). transoms are rather low in all constructions, at about 1.5 meters as measured from the upper side of the floor. this short height of doors is owed to the defensive character of the house. since it did not facilitate a convenient entrance, it was considered to be a suitable strategy so as to repel invaders, as stated by the owners of the houses during the interviews. nuclear families and extended families with plenty of sons and grad-sons were allowed to use higher quality materials for the construction of their houses (kassis, 1980). privileged members of the patriarchic clans, forced families with daughters to use lower quality materials. this fact made the constructions vulnerable and easy to demolish. this issue could be perceived as an explicit spatial depiction of gender discrimination (ibid). fig. 3, 4: 3d view of bofos’ tower and γ-shape plan of a ground floor construction. the two typical housing types met in the village, author’s drawings, field work in any case, all the constructions and land properties were bestowed only to the male descendants. as for the housing facilities, all houses high rise or not, have until today tanks so as to store rainwater for household use. field work has revealed that the village was connected to the national electricity supply network in 1987. the connection to the national fixed telecommunication network was not fulfilled before the mid-90s. in account of all these, all houses had until recently poor facilities. ii. environmental assessment a. location and spatial organization of the settlement apart from the socio-economic and cultural factors, environmental parameters played a predominant role in the production of living space. basic elements of the natural environment as the mountain range of taygetos transfuse semi-mountainous characteristics to the majority of the vernacular settlements of the area of mani, as in the case of korogonianika. the length of the mountain range is 75 km and the width varies between 10 and 20 km., its height varies from 300 to 1214 m. there is also a plateau where the selected case study is located, at about in any case, all the constructions and land properties were bestowed only to the male descendants. as for the housing facilities, all houses high rise or not, have until today tanks so as to store rainwater for household use. field work has revealed that the village was connected to the national electricity supply network in 1987. the connection to the national fixed telecommunication network was not fulfilled before the mid-90s. in account of all these, all houses had until recently poor facilities. environmental assessment location and spatial organization of the settlement apart from the socio-economic and cultural factors, environmental parameters played a predominant role in the production of living space. basic elements of the natural environment as the mountain range of taygetos transfuse semi-mountainous characteristics to the majority of the vernacular settlements of the area of mani, as in the case of korogonianika. the length of the mountain range is 75 km and the width varies between 10 and 20 km., its height varies from 300 to 1214 m. there is also a plateau where the selected case study is located, at about 350m height. all the settlements were located far from the coastal zone, in the mainland. taking into consideration the morphology of the scenery, these settlements were geographically isolated from other rural areas of peloponnese. thus, all settlements were secluded and difficult to connect with each journal of sustainable architecture and civil engineering 2020/2/27 36 map 5 greece map of köppen climate classification 350m height. all the settlements were located far from the coastal zone, in the mainland. taking into consideration the morphology of the scenery, these settlements were geographically isolated from other rural areas of peloponnese. thus, all settlements were secluded and difficult to connect with each other. in these introverted communities, the regime of patriarchic clans, as described before, was the norm that ruled every aspect of daily life. as for the climate conditions, according to the koeppen-geiger map of greece (map 5,6), the area of study is characterized as “hot summer mediterranean”. it is an area with high temperatures during the summer period, low level of humidity during the whole year and moderate temperatures during the winter. it is important to mention that during the winter, high winds are recorded. this climatological feature was estimated by traditional craftsmen that chose favorable locations for each and every settlement. the selected positions provided shelter from the wind. another important characteristic is the kind of vegetation met in the area and the available local natural resources. to be more specific, this type of arid climate is associated with indigenous low height flora, mostly bushes and shreds as thyme and prickly pears. the only indigenous trees are olive trees. fertile enclaves are only rare. the area they cover is usually small. from this point of view, the lack of soil fertility was a crucial factor that affected the socio-economic structure of these settlements until the 50s, when massive internal migration was documented. map 5: greece map of köppen climate classification, available at https://el.wikipedia.org/wiki/%ce%91%cf%81%cf%87%ce%b5%ce%af%ce%bf:greece_map_of_k%c 3%b6ppen_climate_classification_(new).svg. the described area, the district of mani, lakonia, is indicated with the red circle. map 6: greece as depicted in the köppen climate classification, «file:world!koppen!map!.png" by murray c. peel is licensed under cc by-sa 4.0, available at https://search.creativecommons.org/photos/1b973098-fa0b4ff8-b204-0ffce08a7938 as for the orientation of each settlement two types have been documented in the area of mani (saitas, 2001). the first type is met in cases where the whole settlement is constructed along a hillside. in such cases, the long side of each house is placed vertical to the contour lines while the narrow one is facing the slope, which has usually view to the sea. the second type is met when the settlement is placed on a plateau, like the selected case study. the main core of the settlement was aligned with the downwind side of the slope, so as to protect all constructions from the high wind (map 1). each settlement has various public and private open spaces, usually oriented south or south east, so as to reap the maximum benefits of sunlight. the most popular one is a type of other. in these introverted communities, the regime of patriarchic clans, as described before, was the norm that ruled every aspect of daily life. as for the climate conditions, according to the koeppen-geiger map of greece (map 5,6), the area of study is characterized as “hot summer mediterranean”. it is an area with high temperatures during the summer period, low level of humidity during the whole year and moderate temperatures during the winter. it is important to mention that during the winter, high winds are recorded. this climatological feature was estimated by traditional craftsmen that chose favorable locations for each and every settlement. the selected positions provided shelter from the wind. another important characteristic is the kind of vegetation met in the area and the available local natural resources. to be more specific, this type of arid climate is associated with indigenous low height flora, mostly bushes and shreds as thyme 350m height. all the settlements were located far from the coastal zone, in the mainland. taking into consideration the morphology of the scenery, these settlements were geographically isolated from other rural areas of peloponnese. thus, all settlements were secluded and difficult to connect with each other. in these introverted communities, the regime of patriarchic clans, as described before, was the norm that ruled every aspect of daily life. as for the climate conditions, according to the koeppen-geiger map of greece (map 5,6), the area of study is characterized as “hot summer mediterranean”. it is an area with high temperatures during the summer period, low level of humidity during the whole year and moderate temperatures during the winter. it is important to mention that during the winter, high winds are recorded. this climatological feature was estimated by traditional craftsmen that chose favorable locations for each and every settlement. the selected positions provided shelter from the wind. another important characteristic is the kind of vegetation met in the area and the available local natural resources. to be more specific, this type of arid climate is associated with indigenous low height flora, mostly bushes and shreds as thyme and prickly pears. the only indigenous trees are olive trees. fertile enclaves are only rare. the area they cover is usually small. from this point of view, the lack of soil fertility was a crucial factor that affected the socio-economic structure of these settlements until the 50s, when massive internal migration was documented. map 5: greece map of köppen climate classification, available at https://el.wikipedia.org/wiki/%ce%91%cf%81%cf%87%ce%b5%ce%af%ce%bf:greece_map_of_k%c 3%b6ppen_climate_classification_(new).svg. the described area, the district of mani, lakonia, is indicated with the red circle. map 6: greece as depicted in the köppen climate classification, «file:world!koppen!map!.png" by murray c. peel is licensed under cc by-sa 4.0, available at https://search.creativecommons.org/photos/1b973098-fa0b4ff8-b204-0ffce08a7938 as for the orientation of each settlement two types have been documented in the area of mani (saitas, 2001). the first type is met in cases where the whole settlement is constructed along a hillside. in such cases, the long side of each house is placed vertical to the contour lines while the narrow one is facing the slope, which has usually view to the sea. the second type is met when the settlement is placed on a plateau, like the selected case study. the main core of the settlement was aligned with the downwind side of the slope, so as to protect all constructions from the high wind (map 1). each settlement has various public and private open spaces, usually oriented south or south east, so as to reap the maximum benefits of sunlight. the most popular one is a type of map 6 greece as depicted in the köppen climate classification available at https://el.wikipedia.org/wiki/%ce%91%cf%81%cf%8 7%ce%b5%ce%af%ce%bf:greece_map_of_k%c3%b6ppen_climate_classification_(new).svg. the described area, the district of mani, lakonia, is indicated with the red circle «file:world!koppen!map!.png" by murray c. peel is licensed under cc by-sa 4.0, available at https://search.creativecommons.org/photos/1b973098-fa0b-4ff8-b204-0ffce08a7938 350m height. all the settlements were located far from the coastal zone, in the mainland. taking into consideration the morphology of the scenery, these settlements were geographically isolated from other rural areas of peloponnese. thus, all settlements were secluded and difficult to connect with each other. in these introverted communities, the regime of patriarchic clans, as described before, was the norm that ruled every aspect of daily life. as for the climate conditions, according to the koeppen-geiger map of greece (map 5,6), the area of study is characterized as “hot summer mediterranean”. it is an area with high temperatures during the summer period, low level of humidity during the whole year and moderate temperatures during the winter. it is important to mention that during the winter, high winds are recorded. this climatological feature was estimated by traditional craftsmen that chose favorable locations for each and every settlement. the selected positions provided shelter from the wind. another important characteristic is the kind of vegetation met in the area and the available local natural resources. to be more specific, this type of arid climate is associated with indigenous low height flora, mostly bushes and shreds as thyme and prickly pears. the only indigenous trees are olive trees. fertile enclaves are only rare. the area they cover is usually small. from this point of view, the lack of soil fertility was a crucial factor that affected the socio-economic structure of these settlements until the 50s, when massive internal migration was documented. map 5: greece map of köppen climate classification, available at https://el.wikipedia.org/wiki/%ce%91%cf%81%cf%87%ce%b5%ce%af%ce%bf:greece_map_of_k%c 3%b6ppen_climate_classification_(new).svg. the described area, the district of mani, lakonia, is indicated with the red circle. map 6: greece as depicted in the köppen climate classification, «file:world!koppen!map!.png" by murray c. peel is licensed under cc by-sa 4.0, available at https://search.creativecommons.org/photos/1b973098-fa0b4ff8-b204-0ffce08a7938 as for the orientation of each settlement two types have been documented in the area of mani (saitas, 2001). the first type is met in cases where the whole settlement is constructed along a hillside. in such cases, the long side of each house is placed vertical to the contour lines while the narrow one is facing the slope, which has usually view to the sea. the second type is met when the settlement is placed on a plateau, like the selected case study. the main core of the settlement was aligned with the downwind side of the slope, so as to protect all constructions from the high wind (map 1). each settlement has various public and private open spaces, usually oriented south or south east, so as to reap the maximum benefits of sunlight. the most popular one is a type of 37 journal of sustainable architecture and civil engineering 2020/2/27 and prickly pears. the only indigenous trees are olive trees. fertile enclaves are only rare. the area they cover is usually small. from this point of view, the lack of soil fertility was a crucial factor that affected the socio-economic structure of these settlements until the 50s, when massive internal migration was documented. as for the orientation of each settlement two types have been documented in the area of mani (saitas, 2001). the first type is met in cases where the whole settlement is constructed along a hillside. in such cases, the long side of each house is placed vertical to the contour lines while the narrow one is facing the slope, which has usually view to the sea. the second type is met when the settlement is placed on a plateau, like the selected case study. the main core of the settlement was aligned with the downwind side of the slope, so as to protect all constructions from the high wind (map 1). each settlement has various public and private open spaces, usually oriented south or south east, so as to reap the maximum benefits of sunlight. the most popular one is a type of plateau, called in the local dialect “rouga”. it could be described as the precursor of the square, during the late medieval era in greece. in most cases, vernacular settlements have at least two of them, the lower and the upper. having a nodal role (lynch, 1960 “nodes”), they organized neighborhood networks, accommodating social interaction in the micro-scale of the settlement, offering as well thermal comfort because of their favorable location. another important element in terms of environmental assessment, is associated with the analogies between the width of each path and the height of surrounding buildings. this varies from 1:1 to 1:1.5 as estimated during field work. this analogy offers sufficient sunlight for a latitude of 36o. this type of spatial organization eliminates the phenomenon of overlapping shadows met in modern metropolitan areas. thus, all public parts of the settlement support not only social interaction but also improve microclimate conditions inside the settlement. buildings: materials, construction methods and architectural elements as far as the buildings are concerned, the axis of the long side is aligned to the east-west direction so as to place the main entrance at the southern side (see map 1). another typical feature of the vernacular architecture of mani is the small size of doors and windows. this feature is associated with the effort to minimize thermal exchange between the interior and the exterior. this means that, besides socio-cultural reasons, environmental conditions affected the size and location of windows and doors. in most of the cases, the windows are placed on the southern or southeastern façade which is usually the long one. there are no windows on the northern side of the house. other small openings along the south or the southeast façade have been documented so as to enrich the amount of natural light entering the house during the winter period. as for the natural ventilation, most of the vernacular houses of mani, have a special opening above kitchen’s celling that functions as a cooling tower. despite all the effort, houses constructed before the 20th century do not offer cross-ventilation. inefficient ventilation and poor natural daylight are the main disadvantages of this type of vernacular architecture. describing the issue of thermal comfort, the interviews revealed that these vernacular constructions exercise high environmental performance during summer and winter mostly because of the high thermal inertia of stone. the majority of the owners reported only limited use of artificial means for cooling during the summer period, mostly fans. as for the winter, a central heating system is rarely documented. when the houses are used during the winter period, the owners prefer gas heaters. as far as materials are concerned, all constructions are built with load-bearing masonry from local limestone. documentation of these settlements has highlighted the phenomenon of consecutive journal of sustainable architecture and civil engineering 2020/2/27 38 constructions, using architectural parts of antecedent periods (saitas,2001). traditional craftsmen seemed to be aware of the perilous seismic activity in the area. earthquakes had long been a potentially hazardous environmental factor, that all constructions had to take into account. from this point of view, the year 1850 is considered to be a milestone for the evolution of local constructions because of the use of lime plaster in internal and external stone-made masonry. this element reinforced the stability of each construction, reducing the width of masonry. moreover, this new material contributed to the creation of load-bearing arches at the upper part of the internal masonry. the load-bearing arches, visible only from the inside facilitated the creation of rooms with larger width. this innovation of the mid-19th century, improved the prevailing living conditions in the vernacular settlements of mani. the higher point of each arch is calculated at about 3.5 meters, according to field work. for houses with a mezzanine, the higher point of the arch is at about 5 meters as calculated from the inside (fig.7). these architectural elements are found at the village of korogonianika as well as in the majority of the vernacular settlements of mani. conclusions nonetheless, mediterranean vernacular architecture is an example for seismic protection, presenting numerous solutions that could help contemporary constructions (correia, et.al, 2015). following its general principles, these buildings present stable connections among all structural parts. another important feature is associated with the reduction of construction weight in accordance with the height of construction. thus, smaller and lighter stones were chosen for the upper part of the masonry. field work has revealed that most of these constructions have provision for horizontal seismic stresses. the use of horizontal wooden beams is an indicator for this assumption. taking into account all these, these vernacular building shells are well adjusted to the environmental conditions offering solutions for a variety of issues, despite the previously mentioned flaws. the production of space in vernacular settlements of southern greece has followed environmental principles affected by socio-economic parameters and cultural values. the interaction between them has led to specific socio-spatial patterns. the once isolated areas of mani, ruled by blood-related clans, offered poor local resources. these stone-made constructions were the only available option. the effort to achieve maximum thermal comfort both the summer and winter period, has contributed to numerous sustainable architectural solutions. the selection of south or south east orientation and the downwind locations are just a few of them. in addition, the thermal inertial of stone combined with the small windows and doors limited the heat exchange between the internal and external environment.there are though some disadvantages related to the choice of small openings on the façades. the main problem is associated with the inefficient sunlight that penetrates inside the house while also the lack of cross ventilation is considered to be significant. today mechanical interventions have ameliorated the former difficult living condiditions. however, in most of the cases, these houses do not achieve to reach the facilities that contemporary constructions offer. from this point of view, there are numerous challenges, despite their significance in fig. 7 section depicting a typical ground floor construction with load-bearing arches, in the village korogonianika, authors work 39 journal of sustainable architecture and civil engineering 2020/2/27 references about the author tousi evgenia dr.architect-urban and regional planner, adjunct academic staff university of west attica, school of applied arts and culture, department of interior architecture main research area sustainable architecture, urban and regional planning. address e-mail: etousi@uniwa.gr terms of cultural heritage. apart form the building shell itself, the lack of facilities and servises combined with the limited employment opportunities make these communities far less competent than the nearby towns and metropolitan areas. numbers of permanent citizens decline year after year, leading to absolute desolation. side effects of this situation are associated with the poor preservation of vernacular building shells, which are in many cases left in despair. from this point of view, the lack of permanent population in such communities should be considered as a major factor that hinders sustainability in terms of social and spatial cohesion. acknowledgement the author would like to thank mr stavros bofos, owner of bofos’ tower and writer, as well as the residents of the vernacular settlement of korogonianika. cavanagh h., cavanagh w., roy j. (2009) “honoring the dead in the peloponnese” , conference proceedings, , 23-25 april, 2009, sparta, peloponnese, the university of nottingham, centre for spartan and peloponnesian studies greece, csps online publication 2 http://www.nottingham.ac.uk/csps/documents/honoringthedead/papadimitriou.pdf chapin a., davis b., banou e., hitchcock, l.,(2014) “the vapheio tholos tomb and the construction of a sacred landscape in laconia, greece”aegaeum 37, physis, l’environnement naturel et la relation homme-milieudans le monde égéen protohistorique actes de la 14e, rencontre égéenne internationale,paris, institut national d’histoire de l’art (inha),1114 décembre 2012, peeters leuven liege correia m., lourenco p., humberto v. (2015) „seismic retrofitting: learning from vernacular architecture“, crc press, taylor and francis group, london ,uk, p.67-80 https://doi.org/10.1201/b18856 grüning, b. & tuma, r. (2017). space, interaction and communication: sociology in dialogue with spatial studies: an introduction. sociologica. 11. 10.2383/88196. kassis k. (1980) “folkloristic of mani”, vol.a, athens (in greek) koutsilieris a. (1993) “history of mani: ancient, medieval and modern”, papadima publications, athens (in greek) lejeune j.f., sabatino m. (2010) „modern architecture and the mediterranean: vernacular dialogs and contested identities“, routhledge, new york, usa https://doi.org/10.4324/9780203871904 leontidou l. (2001) “cities of silence”, cultural foundation of piraeus corporation publications, 2nd edition, athens (in greek). lipovec n.c., balen v.n. (2008) preventive conservation and maintenance of architectural heritage as means of preservation of the spirit of place , raymond lemaire international centre for conservation, ku leuven, belgium, available at https://www.icomos.org/quebec2008/cd/toindex/77_pdf/77-okqk-292.pdf lynch k. (1960) “image of the city”, imt press, usa mantziou l. (2010) “integration of contemporary buildings to mountainous vernacular settlements” conference proceedings national technical university of athens, 16-19 september 2010 retrieved from http://www. ntua.gr/mirc/6th_conference/presentations/1_main_ sessions/7th_session/mantzioy%20l.pdf (in greek) petronotis a., kamilakis p. (1986) “masons of vernacular architecture in the aegean”, http://kpemakrin.mag.sch.gr/smnrgefyr13/aegean.pdf rapoport a. (1969) “house form and culture”, prentice-hall, university of michigan saitas g. (2001) “mani”, melissa publications, athens (in greek) this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 58 analysis of stress concentration area about the brace of the concrete wall at early age antanas žiliukas1, giedrius žiogas1* 1kaunas university of technology, strength and fracture mechanics centre, kęstučio st. 27, lt-44025 kaunas, lithuania * corresponding author: ziogas.giedrius@gmail.com scientists recently focus on concrete’s hardening early age and its influence to solidity of a structure. because of complex physical – chemical processes and developed strains, stresses appear in concrete and after they exceed tensile strength of concrete develops cracks. in practice it is noted that a structure often cracks prior to commencement of exploitation. therefore this article analyzes the influence of stresses caused by autogenous shrinkage over solidity of structure. the importance of stresses caused by concrete shrinkage significantly increases in places where a cross-section shifts. the stress concentration area develops at these points. one of the stress concentration areas is around the formwork’s transverse brace and stresses due to autogeneous shrinkage are solved. to define stresses, analytical and finite element methods are used. the stresses concentration area is calculated more precisely using the finite elements method, the results obtained are exhaustive and it allows to get a clearer picture of stresses. keywords: autogenous shrinkage, cracks, early age, stress concentration area, finite element method. darnioji architektūra ir statyba 2012. no. 1(1) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction in recent years, there have been a number of scientific works where the influence of concrete early age hardening upon development of cracks is researched. while concrete hardens there are complex chemical and physical processes under proceeding, if not controlled they can negatively impact a structure. when cracks appear in reinforced concrete structures, the structure loses solidity, bearing capacity and it has negative impact on exploitation. so it is important to assess impact from concrete shrinkage and to suppose possible areas of stress concentration. a concentration area develops in places where cross-section of structure changes, i. e. decrease (viau 2010). therefore, it is important to know these weak points and to solve the problem as per technological and structural aspect reducing the impact of stresses upon solidity of structure. one of those places is around transverse brace of formworks, where structure is weaken by transverse continuous opening. it is known from practice that cracks are often noticed at these places. it should be noted that similar problems, when the stress concentration fields develop, are researched by scientists (rees et al. 2012, luo et al. 2012 )the peculiarities of monolithic concrete pouring, factors determining the development of cracks as well as prevention methods were partly discussed in the publications analyzed (žiogas and jočiūnas 2007). similar cases where concentration fields of cracks develop are investigated by scientists (rees et al. 2012, luo et al. 2012), who indicate the appearance of cracks because of stress concentration as negative impact on the exploitation of structure. scientific works establish that depending on attenuation of cross-section, stresses can increase from 3 to 4 times. in practice it is noted that a structure often cracks prior to commencement of exploitation. during the hydration a volume of concrete changes and where areas are restricted because of the concrete shrinkage, inward stresses appear in concrete and after they exceed concrete tensile strength cracks appear (hansen 2011). the factors that influence shrinkage of concrete are given in the picture 1 (holt and leivo 2004). as mentioned above, after appearance of concrete strains, tensile stresses appear as well cct e εσ ⋅= . (here: ec – modulus of elasticity of concrete; εc – strain of concrete). when tensile stresses appeared because of strains exceed concrete tensile strength ctmt f>σ cracks occur. this article analyzes the development of concentration area around transverse brace of formwork when autogenous shrinkage strains are present, shrinkage conditional strain is not estimated because the structure are restricted with formworks that prevent moisture loses from the structure. http://dx.doi.org/10.5755/j01.sace.1.1.2619 59 2. methods calculation methods of concrete strain-stress at early age one of the processes causing cracks in concrete at the early stage of hardening is total shrinkage which develops while concrete is hardening. total shrinkage strain consists of two components (eurocode 2, 2005): ▪ drying shrinkage strain; ▪ autogenous shrinkage strain total shrinkage strain values depend on the composition of the mix, water-cement ratio, time of hardening, geometrical characteristics and the surroundings (relative humidity of the air). since the structure is restrained by formwork, concrete strain caused by moisture loss is not considered,but the autogenous shrinkage is proceeded. peak values of total shrinkage strain will be found along the xx direction of the wall. in this case stresses due to the developed strains can be calculated in the following manner: analysis of stress concentration area about the brace of the concrete wall at early age 69 fig. 1. diagram of shrinkage stages and types as mentioned above, after appearance of concrete strains, tensile stresses appear as well cct e εσ ⋅= . (here: e c modulus of elasticity of concrete; ε c – strain of concrete). when tensile stresses appeared because of strains exceed concrete tensile strength ctmt f>σ cracks occur. this article analyzes the development of concentration area around transverse brace of formwork when autogenous shrinkage strains are present, shrinkage conditional strain is not estimated because the structure are restricted with formworks that prevent moisture loses from the structure. 2. methods calculation methods of concrete strain-stress at early age one of the processes causing cracks in concrete at the early stage of hardening is total shrinkage which develops while concrete is hardening. total shrinkage strain consists of two components (eurocode 2, 2005): • drying shrinkage strain; • autogenous shrinkage strain total shrinkage strain values depend on the composition of the mix, water-cement ratio, time of hardening, geometrical characteristics and the surroundings (relative humidity of the air). since the structure is restrained by formwork, concrete strain caused by moisture loss is not considered,but the autogenous shrinkage is proceeded. peak values of total shrinkage strain will be found along the xx direction of the wall. in this case stresses due to the developed strains can be calculated in the following manner: )( · tcxxxx eεσ = (1) where: ε xx – autogenous shrinkage, e c(t) ·modulus of elasticity at age t. to determine autogenous shrinkage according to the following mathematical model (jci technical committee, tazawa and miyazawa, 2002): ( ) tctc cw βεγε ⋅⋅⋅= )/( 0 (2) when 0,2≤w/c≤0,5 : )]/(2,7exp[3070)/( 0 cwcw c −=ε (3) when w/c> 0,5: 80)/( 0 =cw c ε (4) ])(exp[1 0 b t tta −−−=β (5) here ε c(t) ·10 -6 is the autogenous shrinkage of concrete at age t; γ is the coefficient which assesses the variety of cement, γ=1, when regular portland cement is used; ε c0 ·10 -6 are the highest autogenous shrinkage strains of the cement stone with the corresponding ratio of water and binding material w/c; β t is a coefficient which assesses autogenous shrinkage in relation to time; w/c is the watercement ratio; t is age of concrete in days ; t 0 is the initial time of binding in days ; a and b are the coefficients taken from table 1. autogenous shrinkage of concrete (cement c=350 kg/m 3; ,w/c=0,415; concentration of coarse aggregate φ st = 0,375) was calculated using these dependencies. concrete shrinkage early age long term drying autogenous thermal drying autogenous thermal corbanation (1) where: εxx – autogenous shrinkage, ec(t) – modulus of elasticity at age t. to determine autogenous shrinkage according to the following mathematical model (jci technical committee, tazawa and miyazawa, 2002): ( ) tctc cw βεγε ⋅⋅⋅= )/(0 (2) when 0,2≤w/c≤0,5: analysis of stress concentration area about the brace of the concrete wall at early age 69 fig. 1. diagram of shrinkage stages and types as mentioned above, after appearance of concrete strains, tensile stresses appear as well cct e εσ ⋅= . (here: e c modulus of elasticity of concrete; ε c – strain of concrete). when tensile stresses appeared because of strains exceed concrete tensile strength ctmt f>σ cracks occur. this article analyzes the development of concentration area around transverse brace of formwork when autogenous shrinkage strains are present, shrinkage conditional strain is not estimated because the structure are restricted with formworks that prevent moisture loses from the structure. 2. methods calculation methods of concrete strain-stress at early age one of the processes causing cracks in concrete at the early stage of hardening is total shrinkage which develops while concrete is hardening. total shrinkage strain consists of two components (eurocode 2, 2005): • drying shrinkage strain; • autogenous shrinkage strain total shrinkage strain values depend on the composition of the mix, water-cement ratio, time of hardening, geometrical characteristics and the surroundings (relative humidity of the air). since the structure is restrained by formwork, concrete strain caused by moisture loss is not considered,but the autogenous shrinkage is proceeded. peak values of total shrinkage strain will be found along the xx direction of the wall. in this case stresses due to the developed strains can be calculated in the following manner: )( · tcxxxx eεσ = (1) where: ε xx – autogenous shrinkage, e c(t) ·modulus of elasticity at age t. to determine autogenous shrinkage according to the following mathematical model (jci technical committee, tazawa and miyazawa, 2002): ( ) tctc cw βεγε ⋅⋅⋅= )/( 0 (2) when 0,2≤w/c≤0,5 : )]/(2,7exp[3070)/( 0 cwcw c −=ε (3) 80)/( 0 =cw c ε (4) ])(exp[1 0 b t tta −−−=β (5) here ε c(t) ·10 -6 is the autogenous shrinkage of concrete at age t; γ is the coefficient which assesses the variety of cement, γ=1, when regular portland cement is used; ε c0 ·10 -6 are the highest autogenous shrinkage strains of the cement stone with the corresponding ratio of water and binding material w/c; β t is a coefficient which assesses autogenous shrinkage in relation to time; w/c is the watercement ratio; t is age of concrete in days ; t 0 is the initial time of binding in days ; a and b are the coefficients taken from table 1. autogenous shrinkage of concrete (cement c=350 kg/m 3; ,w/c=0,415; concentration of coarse aggregate φ st = 0,375) was calculated using these dependencies. concrete shrinkage early age long term drying autogenous thermal drying autogenous thermal corbanation (3) when w/c> 0,5: analysis of stress concentration area about the brace of the concrete wall at early age 69 fig. 1. diagram of shrinkage stages and types as mentioned above, after appearance of concrete strains, tensile stresses appear as well cct e εσ ⋅= . (here: e c modulus of elasticity of concrete; ε c – strain of concrete). when tensile stresses appeared because of strains exceed concrete tensile strength ctmt f>σ cracks occur. this article analyzes the development of concentration area around transverse brace of formwork when autogenous shrinkage strains are present, shrinkage conditional strain is not estimated because the structure are restricted with formworks that prevent moisture loses from the structure. 2. methods calculation methods of concrete strain-stress at early age one of the processes causing cracks in concrete at the early stage of hardening is total shrinkage which develops while concrete is hardening. total shrinkage strain consists of two components (eurocode 2, 2005): • drying shrinkage strain; • autogenous shrinkage strain total shrinkage strain values depend on the composition of the mix, water-cement ratio, time of hardening, geometrical characteristics and the surroundings (relative humidity of the air). since the structure is restrained by formwork, concrete strain caused by moisture loss is not considered,but the autogenous shrinkage is proceeded. peak values of total shrinkage strain will be found along the xx direction of the wall. in this case stresses due to the developed strains can be calculated in the following manner: )( · tcxxxx eεσ = (1) where: ε xx – autogenous shrinkage, e c(t) ·modulus of elasticity at age t. to determine autogenous shrinkage according to the following mathematical model (jci technical committee, tazawa and miyazawa, 2002): ( ) tctc cw βεγε ⋅⋅⋅= )/( 0 (2) when 0,2≤w/c≤0,5 : )]/(2,7exp[3070)/( 0 cwcw c −=ε (3) when w/c> 0,5: 80)/( 0 =cw c ε (4) ])(exp[1 0 b t tta −−−=β (5) here ε c(t) ·10 -6 is the autogenous shrinkage of concrete at age t; γ is the coefficient which assesses the variety of cement, γ=1, when regular portland cement is used; ε c0 ·10 -6 are the highest autogenous shrinkage strains of the cement stone with the corresponding ratio of water and binding material w/c; β t is a coefficient which assesses autogenous shrinkage in relation to time; w/c is the watercement ratio; t is age of concrete in days ; t 0 is the initial time of binding in days ; a and b are the coefficients taken from table 1. autogenous shrinkage of concrete (cement c=350 kg/m 3; ,w/c=0,415; concentration of coarse aggregate φ st = 0,375) was calculated using these dependencies. concrete shrinkage early age long term drying autogenous thermal drying autogenous thermal corbanation (4) ])(exp[1 0 b t tta −−−=β (5) here εc(t)·10-6 is the autogenous shrinkage of concrete at age t; γ is the coefficient which assesses the variety of cement, γ=1, when regular portland cement is used; εc0·10-6 are the highest autogenous shrinkage strains of the cement stone with the corresponding ratio of water and binding material w/c; βt is a coefficient which assesses autogenous shrinkage in relation to time; w/c is the watercement ratio; t is age of concrete in days; t0 is the initial time of binding in days; a and b are the coefficients taken from table 1. autogenous shrinkage of concrete (cement c=350 kg/m3,w/c=0,415; concentration of coarse aggregate – φst= 0,375) was calculated using these dependencies. table 1. values of coefficients a and b w/c coeff. 0,2 0,3 0,4 0,5 0,6 a 1,2 1,5 0,6 0,1 0,03 b 0,4 0,4 0,5 0,7 0,8 fig. 2 shows the dependencies of concrete stresses due to its autogenous shrinkage and hardening time. these dependencies were obtained using formulas 1 and 5. compressive strength of hardening concrete were obtained by means of an industrial experiment (žiogas et al. 2007), while its tensile strength and modulus of elasticity were calculated using the corresponding formulas and ec2 regulations. modulus of elasticity of concrete are given in table 2. table 2. modulus of elasticity of concrete hardening time, days 1 2 3 7 14 28 ec, mpa 23920 26870 28290 30620 31990 33000 when values of internal stresses are known, the area of stress concentration around the hole can be calculated. stresses are calculated by applying analytical and numerical methods. the former method of calculating the area of stresses concentration uses the recommended formulas (žiliukas et al. 2010). radial normal stresses around hole σrr are obtained from the formula given below: analysis of stress concentration area about the brace of the concrete wall at early age 71 radial normal stresses around hole σ rr are obtained from the formula given below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −− ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 2 2 2 2 2 3 112cos 2 1 2 r a r a r a xxxx rr θ σσ σ (6) here: a is the radius of the hole 10 mm, r is the radius from the centre of the hole to any other point. stresses near the hole are calculated, therefore the radius a=r, and stresses σ rr =0 when r>>a, stresses are calculated according to the formula given below: [ ])2cos(1 2 1 θσσ += xxrr (7) it can be seen from the formula that stresses σ rr depend on angle θ. when θ=0, σ rr ≈ σ xx , when θ =90, σ rr ≈ 0. circular normal stresses are calculated from the formula below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += 4 4 2 2 312cos 2 1 2 r a r a xxxx θ σσ σ θθ (8) when a=r, stresses σ θθ are calculated from : ( )( )θ σ σ θθ 2cos42 2 −= xx (9) the stress concentration, i.e. σ θθ =3 σ xx is formed when angle θ=90°. moving further from the centre of the hole, i.e., when r>>a, stresses change with angle θ, σ θθ(0) =0 ir σ θθ(90) = σ xx. tangential stresses are obtained from the following formula: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −−= 2 2 2 2 3112sin 2 r a r a xx r θ σ σ θ …(10) when a=r, stresses σ rθ are calculated: 0= θ σ r …(11) when angle θ=0, σ rθ =0, circular stresses σ θθ are key stresses σ 1, and radial stresses σ rr are key stresses σ 2 . when a biaxial stress state is present, equivalent stresses are calculated according to mises (liu, 2005): 21 2 2 2 1 σσσσσ −+= i … (12) 3. results and discussion stresses obtained analytically are presented in table 3. while calculating the area of stress concentration, the increment of stresses due to the decreased cross section area a net =a-2r is taken into consideration (nominal stresses) table 3. stresses around the hole calculated hardening time, days stresses , mpa σ nom σ 1 σ 2 σ i,a 1 0,62 1,87 0,62 1,65 2 1,05 3,16 1,05 2,79 3 1,31 3,92 1,31 3,46 7 1,65 4,95 1,63 4,95 14 2,15 6,44 2,15 5,68 28 2,38 7,14 2,38 6,30 (6) analysis of stress concentration area about the brace of the concrete wall at early age 69 fig. 1. diagram of shrinkage stages and types as mentioned above, after appearance of concrete strains, tensile stresses appear as well cct e εσ ⋅= . (here: e c modulus of elasticity of concrete; ε c – strain of concrete). when tensile stresses appeared because of strains exceed concrete tensile strength ctmt f>σ cracks occur. this article analyzes the development of concentration area around transverse brace of formwork when autogenous shrinkage strains are present, shrinkage conditional strain is not estimated because the structure are restricted with formworks that prevent moisture loses from the structure. 2. methods calculation methods of concrete strain-stress at early age one of the processes causing cracks in concrete at the early stage of hardening is total shrinkage which develops while concrete is hardening. total shrinkage strain consists of two components (eurocode 2, 2005): • drying shrinkage strain; • autogenous shrinkage strain total shrinkage strain values depend on the composition of the mix, water-cement ratio, time of hardening, geometrical characteristics and the surroundings (relative humidity of the air). since the structure is restrained by formwork, concrete strain caused by moisture loss is not considered,but the autogenous shrinkage is proceeded. peak values of total shrinkage strain will be found along the xx direction of the wall. in this case stresses due to the developed strains can be calculated in the following manner: )( · tcxxxx eεσ = (1) where: ε xx – autogenous shrinkage, e c(t) ·modulus of elasticity at age t. to determine autogenous shrinkage according to the following mathematical model (jci technical committee, tazawa and miyazawa, 2002): ( ) tctc cw βεγε ⋅⋅⋅= )/( 0 (2) when 0,2≤w/c≤0,5 : )]/(2,7exp[3070)/( 0 cwcw c −=ε (3) when w/c> 0,5: 80)/( 0 =cw c ε (4) ])(exp[1 0 b t tta −−−=β (5) here ε c(t) ·10 -6 is the autogenous shrinkage of concrete at age t; γ is the coefficient which assesses the variety of cement, γ=1, when regular portland cement is used; ε c0 ·10 -6 are the highest autogenous shrinkage strains of the cement stone with the corresponding ratio of water and binding material w/c; β t is a coefficient which assesses autogenous shrinkage in relation to time; w/c is the watercement ratio; t is age of concrete in days ; t 0 is the initial time of binding in days ; a and b are the coefficients taken from table 1. autogenous shrinkage of concrete (cement c=350 kg/m 3; ,w/c=0,415; concentration of coarse aggregate φ st = 0,375) was calculated using these dependencies. concrete shrinkage early age long term drying autogenous thermal drying autogenous thermal corbanation fig. 1. diagram of shrinkage stages and types 60 here: a is the radius of the hole 10 mm, r is the radius from the centre of the hole to any other point. a.žiliukas, g.žiogas 70 table 1 . values of coefficients a and b w/c coeff. 0,2 0,3 0,4 0,5 0,6 a 1,2 1,5 0,6 0,1 0,03 b 0,4 0,4 0,5 0,7 0,8 fig. 2 shows the dependencies of concrete stresses due to its autogenous shrinkage and hardening time. these dependencies were obtained using formulas 1 and 5. compressive strength of hardening concrete were obtained by means of an industrial experiment (žiogas et al. 2007), while its tensile strength and modulus of elasticity were calculated using the corresponding formulas and ec2 regulations. modulus of elasticity of concrete are given in table 2. table 2. modulus of elasticity of concrete hardening time, days 1 2 3 7 14 28 e c , mpa 23920 26870 28290 30620 31990 33000 fig. 2. stresses developed during the hardening of concrete and tensile strength of concrete: calculated and experimental. here : σ xx are internal stresses in concrete caused by autogenous shrinkage; f ct(exp) is the tensile strength of concrete calculated from experimental compressive strength fig. 3. scheme for calculating around the transverse brace of formwork. here : σ xx are the stresses due to autogenous shrinkage of concrete; a is the radius of the hole ; r is a point removed a certain distance from the centre of the hole ; θ is the angle from axis x; t is the thickness of the member; w – is the width of the element when values of internal stresses are known, the area of stress concentration around the hole can be calculated. stresses are calculated by applying analytical and numerical methods. the former method of calculating the area of stresses concentration uses the recommended formulas (žiliukas et al. 2010). fig. 2. stresses developed during the hardening of concrete and tensile strength of concrete: calculated and experimental. here : σxx are internal stresses in concrete caused by autogenous shrinkage; fct(exp) is the tensile strength of concrete calculated from experimental compressive strength a.žiliukas, g.žiogas 70 table 1 . values of coefficients a and b w/c coeff. 0,2 0,3 0,4 0,5 0,6 a 1,2 1,5 0,6 0,1 0,03 b 0,4 0,4 0,5 0,7 0,8 fig. 2 shows the dependencies of concrete stresses due to its autogenous shrinkage and hardening time. these dependencies were obtained using formulas 1 and 5. compressive strength of hardening concrete were obtained by means of an industrial experiment (žiogas et al. 2007), while its tensile strength and modulus of elasticity were calculated using the corresponding formulas and ec2 regulations. modulus of elasticity of concrete are given in table 2. table 2. modulus of elasticity of concrete hardening time, days 1 2 3 7 14 28 e c , mpa 23920 26870 28290 30620 31990 33000 fig. 2. stresses developed during the hardening of concrete and tensile strength of concrete: calculated and experimental. here : σ xx are internal stresses in concrete caused by autogenous shrinkage; f ct(exp) is the tensile strength of concrete calculated from experimental compressive strength fig. 3. scheme for calculating around the transverse brace of formwork. here : σ xx are the stresses due to autogenous shrinkage of concrete; a is the radius of the hole ; r is a point removed a certain distance from the centre of the hole ; θ is the angle from axis x; t is the thickness of the member; w – is the width of the element when values of internal stresses are known, the area of stress concentration around the hole can be calculated. stresses are calculated by applying analytical and numerical methods. the former method of calculating the area of stresses concentration uses the recommended formulas (žiliukas et al. 2010). fig. 3. scheme for calculating around the transverse brace of formwork. here : σxx are the stresses due to autogenous shrinkage of concrete; a is the radius of the hole ; r is a point removed a certain distance from the centre of the hole ; θ is the angle from axis x; t is the thickness of the member; w – is the width of the element stresses near the hole are calculated, therefore the radius a=r, and stresses σrr=0. when r>>a, stresses are calculated according to the formula given below: analysis of stress concentration area about the brace of the concrete wall at early age 71 radial normal stresses around hole σ rr are obtained from the formula given below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −− ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 2 2 2 2 2 3 112cos 2 1 2 r a r a r a xxxx rr θ σσ σ (6) here: a is the radius of the hole 10 mm, r is the radius from the centre of the hole to any other point. stresses near the hole are calculated, therefore the radius a=r, and stresses σ rr =0 when r>>a, stresses are calculated according to the formula given below: [ ])2cos(1 2 1 θσσ += xxrr (7) it can be seen from the formula that stresses σ rr depend on angle θ. when θ=0, σ rr ≈ σ xx , when θ =90, σ rr ≈ 0. circular normal stresses are calculated from the formula below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += 4 4 2 2 312cos 2 1 2 r a r a xxxx θ σσ σ θθ (8) when a=r, stresses σ θθ are calculated from : ( )( )θ σ σ θθ 2cos42 2 −= xx (9) the stress concentration, i.e. σ θθ =3 σ xx is formed when angle θ=90°. moving further from the centre of the hole, i.e., when r>>a, stresses change with angle θ, σ θθ(0) =0 ir σ θθ(90) = σ xx. tangential stresses are obtained from the following formula: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −−= 2 2 2 2 3112sin 2 r a r a xx r θ σ σ θ …(10) when a=r, stresses σ rθ are calculated: 0= θ σ r …(11) when angle θ=0, σ rθ =0, circular stresses σ θθ are key stresses σ 1, and radial stresses σ rr are key stresses σ 2 . when a biaxial stress state is present, equivalent stresses are calculated according to mises (liu, 2005): 21 2 2 2 1 σσσσσ −+= i … (12) 3. results and discussion stresses obtained analytically are presented in table 3. while calculating the area of stress concentration, the increment of stresses due to the decreased cross section area a net =a-2r is taken into consideration (nominal stresses) table 3. stresses around the hole calculated hardening time, days stresses , mpa σ nom σ 1 σ 2 σ i,a 1 0,62 1,87 0,62 1,65 2 1,05 3,16 1,05 2,79 3 1,31 3,92 1,31 3,46 7 1,65 4,95 1,63 4,95 14 2,15 6,44 2,15 5,68 28 2,38 7,14 2,38 6,30 (7) it can be seen from the formula that stresses σrr depend on angle θ. when θ=0, σrr≈ σxx , when θ =90, σrr≈ 0. circular normal stresses are calculated from the formula below: analysis of stress concentration area about the brace of the concrete wall at early age 71 radial normal stresses around hole σ rr are obtained from the formula given below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −− ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 2 2 2 2 2 3 112cos 2 1 2 r a r a r a xxxx rr θ σσ σ (6) here: a is the radius of the hole 10 mm, r is the radius from the centre of the hole to any other point. stresses near the hole are calculated, therefore the radius a=r, and stresses σ rr =0 when r>>a, stresses are calculated according to the formula given below: [ ])2cos(1 2 1 θσσ += xxrr (7) it can be seen from the formula that stresses σ rr depend on angle θ. when θ=0, σ rr ≈ σ xx , when θ =90, σ rr ≈ 0. circular normal stresses are calculated from the formula below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += 4 4 2 2 312cos 2 1 2 r a r a xxxx θ σσ σ θθ (8) when a=r, stresses σ θθ are calculated from : ( )( )θ σ σ θθ 2cos42 2 −= xx (9) the stress concentration, i.e. σ θθ =3 σ xx is formed when angle θ=90°. moving further from the centre of the hole, i.e., when r>>a, stresses change with angle θ, σ θθ(0) =0 ir σ θθ(90) = σ xx. tangential stresses are obtained from the following formula: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −−= 2 2 2 2 3112sin 2 r a r a xx r θ σ σ θ …(10) when a=r, stresses σ rθ are calculated: 0= θ σ r …(11) when angle θ=0, σ rθ =0, circular stresses σ θθ are key stresses σ 1, and radial stresses σ rr are key stresses σ 2 . when a biaxial stress state is present, equivalent stresses are calculated according to mises (liu, 2005): 21 2 2 2 1 σσσσσ −+= i … (12) 3. results and discussion stresses obtained analytically are presented in table 3. while calculating the area of stress concentration, the increment of stresses due to the decreased cross section area a net =a-2r is taken into consideration (nominal stresses) table 3. stresses around the hole calculated hardening time, days stresses , mpa σ nom σ 1 σ 2 σ i,a 1 0,62 1,87 0,62 1,65 2 1,05 3,16 1,05 2,79 3 1,31 3,92 1,31 3,46 7 1,65 4,95 1,63 4,95 14 2,15 6,44 2,15 5,68 28 2,38 7,14 2,38 6,30 (8) when a=r, stresses σθθ are calculated from: analysis of stress concentration area about the brace of the concrete wall at early age 71 radial normal stresses around hole σ rr are obtained from the formula given below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −− ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 2 2 2 2 2 3 112cos 2 1 2 r a r a r a xxxx rr θ σσ σ (6) here: a is the radius of the hole 10 mm, r is the radius from the centre of the hole to any other point. stresses near the hole are calculated, therefore the radius a=r, and stresses σ rr =0 when r>>a, stresses are calculated according to the formula given below: [ ])2cos(1 2 1 θσσ += xxrr (7) it can be seen from the formula that stresses σ rr depend on angle θ. when θ=0, σ rr ≈ σ xx , when θ =90, σ rr ≈ 0. circular normal stresses are calculated from the formula below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += 4 4 2 2 312cos 2 1 2 r a r a xxxx θ σσ σ θθ (8) when a=r, stresses σ θθ are calculated from : ( )( )θ σ σ θθ 2cos42 2 −= xx (9) the stress concentration, i.e. σ θθ =3 σ xx is formed when angle θ=90°. moving further from the centre of the hole, i.e., when r>>a, stresses change with angle θ, σ θθ(0) =0 ir σ θθ(90) = σ xx. tangential stresses are obtained from the following formula: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −−= 2 2 2 2 3112sin 2 r a r a xx r θ σ σ θ …(10) when a=r, stresses σ rθ are calculated: 0= θ σ r …(11) when angle θ=0, σ rθ =0, circular stresses σ θθ are key stresses σ 1, and radial stresses σ rr are key stresses σ 2 . when a biaxial stress state is present, equivalent stresses are calculated according to mises (liu, 2005): 21 2 2 2 1 σσσσσ −+= i … (12) 3. results and discussion stresses obtained analytically are presented in table 3. while calculating the area of stress concentration, the increment of stresses due to the decreased cross section area a net =a-2r is taken into consideration (nominal stresses) table 3. stresses around the hole calculated hardening time, days stresses , mpa σ nom σ 1 σ 2 σ i,a 1 0,62 1,87 0,62 1,65 2 1,05 3,16 1,05 2,79 3 1,31 3,92 1,31 3,46 7 1,65 4,95 1,63 4,95 14 2,15 6,44 2,15 5,68 28 2,38 7,14 2,38 6,30 (9) the stress concentration, i. e. σθθ=3 σxx is formed when angle θ=90°. moving further from the centre of the hole, i. e., when r>>a, stresses change with angle θ, σθθ(0)=0 ir σθθ(90)= σxx. tangential stresses are obtained from the following formula: analysis of stress concentration area about the brace of the concrete wall at early age 71 radial normal stresses around hole σ rr are obtained from the formula given below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −− ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 2 2 2 2 2 3 112cos 2 1 2 r a r a r a xxxx rr θ σσ σ (6) here: a is the radius of the hole 10 mm, r is the radius from the centre of the hole to any other point. stresses near the hole are calculated, therefore the radius a=r, and stresses σ rr =0 when r>>a, stresses are calculated according to the formula given below: [ ])2cos(1 2 1 θσσ += xxrr (7) it can be seen from the formula that stresses σ rr depend on angle θ. when θ=0, σ rr ≈ σ xx , when θ =90, σ rr ≈ 0. circular normal stresses are calculated from the formula below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += 4 4 2 2 312cos 2 1 2 r a r a xxxx θ σσ σ θθ (8) when a=r, stresses σ θθ are calculated from : ( )( )θ σ σ θθ 2cos42 2 −= xx (9) the stress concentration, i.e. σ θθ =3 σ xx is formed when angle θ=90°. moving further from the centre of the hole, i.e., when r>>a, stresses change with angle θ, σ θθ(0) =0 ir σ θθ(90) = σ xx. tangential stresses are obtained from the following formula: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −−= 2 2 2 2 3112sin 2 r a r a xx r θ σ σ θ …(10) when a=r, stresses σ rθ are calculated: 0= θ σ r …(11) when angle θ=0, σ rθ =0, circular stresses σ θθ are key stresses σ 1, and radial stresses σ rr are key stresses σ 2 . when a biaxial stress state is present, equivalent stresses are calculated according to mises (liu, 2005): 21 2 2 2 1 σσσσσ −+= i … (12) 3. results and discussion stresses obtained analytically are presented in table 3. while calculating the area of stress concentration, the increment of stresses due to the decreased cross section area a net =a-2r is taken into consideration (nominal stresses) table 3. stresses around the hole calculated hardening time, days stresses , mpa σ nom σ 1 σ 2 σ i,a 1 0,62 1,87 0,62 1,65 2 1,05 3,16 1,05 2,79 3 1,31 3,92 1,31 3,46 7 1,65 4,95 1,63 4,95 14 2,15 6,44 2,15 5,68 28 2,38 7,14 2,38 6,30 (10) when a=r, stresses σrθ are calculated: analysis of stress concentration area about the brace of the concrete wall at early age 71 radial normal stresses around hole σ rr are obtained from the formula given below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −− ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 2 2 2 2 2 3 112cos 2 1 2 r a r a r a xxxx rr θ σσ σ (6) here: a is the radius of the hole 10 mm, r is the radius from the centre of the hole to any other point. stresses near the hole are calculated, therefore the radius a=r, and stresses σ rr =0 when r>>a, stresses are calculated according to the formula given below: [ ])2cos(1 2 1 θσσ += xxrr (7) it can be seen from the formula that stresses σ rr depend on angle θ. when θ=0, σ rr ≈ σ xx , when θ =90, σ rr ≈ 0. circular normal stresses are calculated from the formula below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += 4 4 2 2 312cos 2 1 2 r a r a xxxx θ σσ σ θθ (8) when a=r, stresses σ θθ are calculated from : ( )( )θ σ σ θθ 2cos42 2 −= xx (9) the stress concentration, i.e. σ θθ =3 σ xx is formed when angle θ=90°. moving further from the centre of the hole, i.e., when r>>a, stresses change with angle θ, σ θθ(0) =0 ir σ θθ(90) = σ xx. tangential stresses are obtained from the following formula: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −−= 2 2 2 2 3112sin 2 r a r a xx r θ σ σ θ …(10) when a=r, stresses σ rθ are calculated: 0= θ σ r …(11) when angle θ=0, σ rθ =0, circular stresses σ θθ are key stresses σ 1, and radial stresses σ rr are key stresses σ 2 . when a biaxial stress state is present, equivalent stresses are calculated according to mises (liu, 2005): 21 2 2 2 1 σσσσσ −+= i … (12) 3. results and discussion stresses obtained analytically are presented in table 3. while calculating the area of stress concentration, the increment of stresses due to the decreased cross section area a net =a-2r is taken into consideration (nominal stresses) table 3. stresses around the hole calculated hardening time, days stresses , mpa σ nom σ 1 σ 2 σ i,a 1 0,62 1,87 0,62 1,65 2 1,05 3,16 1,05 2,79 3 1,31 3,92 1,31 3,46 7 1,65 4,95 1,63 4,95 14 2,15 6,44 2,15 5,68 28 2,38 7,14 2,38 6,30 (11) when angle θ=0, σrθ =0, circular stresses σθθ are key stresses σ1, and radial stresses σrr are key stresses σ2. when a biaxial stress state is present, equivalent stresses are calculated according to mises (liu, 2005): analysis of stress concentration area about the brace of the concrete wall at early age 71 radial normal stresses around hole σ rr are obtained from the formula given below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −− ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 2 2 2 2 2 3 112cos 2 1 2 r a r a r a xxxx rr θ σσ σ (6) here: a is the radius of the hole 10 mm, r is the radius from the centre of the hole to any other point. stresses near the hole are calculated, therefore the radius a=r, and stresses σ rr =0 when r>>a, stresses are calculated according to the formula given below: [ ])2cos(1 2 1 θσσ += xxrr (7) it can be seen from the formula that stresses σ rr depend on angle θ. when θ=0, σ rr ≈ σ xx , when θ =90, σ rr ≈ 0. circular normal stresses are calculated from the formula below: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += 4 4 2 2 312cos 2 1 2 r a r a xxxx θ σσ σ θθ (8) when a=r, stresses σ θθ are calculated from : ( )( )θ σ σ θθ 2cos42 2 −= xx (9) the stress concentration, i.e. σ θθ =3 σ xx is formed when angle θ=90°. moving further from the centre of the hole, i.e., when r>>a, stresses change with angle θ, σ θθ(0) =0 ir σ θθ(90) = σ xx. tangential stresses are obtained from the following formula: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −−= 2 2 2 2 3112sin 2 r a r a xx r θ σ σ θ …(10) when a=r, stresses σ rθ are calculated: 0= θ σ r …(11) when angle θ=0, σ rθ =0, circular stresses σ θθ are key stresses σ 1, and radial stresses σ rr are key stresses σ 2 . when a biaxial stress state is present, equivalent stresses are calculated according to mises (liu, 2005): 21 2 2 2 1 σσσσσ −+= i … (12) 3. results and discussion stresses obtained analytically are presented in table 3. while calculating the area of stress concentration, the increment of stresses due to the decreased cross section area a net =a-2r is taken into consideration (nominal stresses) table 3. stresses around the hole calculated hardening time, days stresses , mpa σ nom σ 1 σ 2 σ i,a 1 0,62 1,87 0,62 1,65 2 1,05 3,16 1,05 2,79 3 1,31 3,92 1,31 3,46 7 1,65 4,95 1,63 4,95 14 2,15 6,44 2,15 5,68 28 2,38 7,14 2,38 6,30 (12) 3. results and discussion stresses obtained analytically are presented in table 3. while calculating the area of stress concentration, the increment of stresses due to the decreased cross – section area anet=a-2r is taken into consideration (nominal stresses). table 3. stresses around the hole calculated hardening time, days stresses, mpa σnom σ1 σ2 σi,a 1 0,62 1,87 0,62 1,65 2 1,05 3,16 1,05 2,79 3 1,31 3,92 1,31 3,46 7 1,65 4,95 1,63 4,95 14 2,15 6,44 2,15 5,68 28 2,38 7,14 2,38 6,30 in the numerical calculation of stresses, the finite element method uses the ansys 12 program; the results obtained are presented in table 4. in the finite element method calculation, a geometrical model is made for ¼ of the structural member, and it is indicated in the program that the member is symmetrical around the x and y axes. such a model does not impact calculation results; besides, fewer computer resources are used. table 4. stresses calculated using the finite element method (with ansys 12 program) hardening time days stresses, mpa margin σxx σ1 σ2 σi,s (σi,s-σi,a)/ σi,s·100% 1 0,57 1,71 0,56 1,71 3,51 2 0,96 2,88 0,95 2,88 3,13 3 1,19 3,57 1,18 3,57 3,08 7 1,65 4,95 1,63 4,95 0,00 14 1,96 5,87 1,94 5,88 3,40 28 2,18 6,47 2,11 6,46 2,48 61 maximum margin is 3,5 % in the analytically and numerically calculated equivalent stresses σi. a.žiliukas, g.žiogas 72 in the numerical calculation of stresses, the finite element method uses the ansys 12 program; the results obtained are presented in table 4. in the finite element method calculation, a geometrical model is made for ¼ of the structural member, and it is indicated in the program that the member is symmetrical around the x and y axes. such a model does not impact calculation results; besides, fewer computer resources are used. maximum margin is 3,5 % in the analytically and numerically calculated equivalent stresses σ i table 4. stresses calculated using the finite element method (with ansys 12 program) hardening time days stresses, mpa margin σ xx σ 1 σ 2 σ i,s (σ i,s -σ i,a )/ σ i,s ·100% 1 0,57 1,71 0,56 1,71 3,51 2 0,96 2,88 0,95 2,88 3,13 3 1,19 3,57 1,18 3,57 3,08 7 1,65 4,95 1,63 4,95 0,00 14 1,96 5,87 1,94 5,88 3,40 28 2,18 6,47 2,11 6,46 2,48 fig. 4. distribution of the area of stress concentration (n/mm 2 ) around the hole (after 3 days of hardening) fig. 5 . comparison of stresses and tensile strengths of concrete. here: σ xx are stresses caused by autogenous shrinkage of concrete; f ct(exp) is the tensile strength of concrete calculated from experimental compressive strength; σ i,a are the stresses obtained using the analitical method; σ i,s are the stresses obtained using the numerical method with program ansys the numerical problem solution allows to calculate the stress distribution around the transverse braces at any angle θ and the radius of the hole. numerical method obtained the stress distribution throughout the structure, which allows a better analysis of the construction work and predict crack growth. numerical method is more accurate and comprehensive as analytical method. it is obvious from the results obtained, that stresses three times as big as those impacting the member σ xx develop near the hole; they exceed the tensile strength of concrete within the first days of hardening. micro cracks appear at these locations even before the exploitation of the structural member begins. fig. 4. distribution of the area of stress concentration (n/mm2) around the hole (after 3 days of hardening) a.žiliukas, g.žiogas 72 in the numerical calculation of stresses, the finite element method uses the ansys 12 program; the results obtained are presented in table 4. in the finite element method calculation, a geometrical model is made for ¼ of the structural member, and it is indicated in the program that the member is symmetrical around the x and y axes. such a model does not impact calculation results; besides, fewer computer resources are used. maximum margin is 3,5 % in the analytically and numerically calculated equivalent stresses σ i table 4. stresses calculated using the finite element method (with ansys 12 program) hardening time days stresses, mpa margin σ xx σ 1 σ 2 σ i,s (σ i,s -σ i,a )/ σ i,s ·100% 1 0,57 1,71 0,56 1,71 3,51 2 0,96 2,88 0,95 2,88 3,13 3 1,19 3,57 1,18 3,57 3,08 7 1,65 4,95 1,63 4,95 0,00 14 1,96 5,87 1,94 5,88 3,40 28 2,18 6,47 2,11 6,46 2,48 fig. 4. distribution of the area of stress concentration (n/mm 2 ) around the hole (after 3 days of hardening) fig. 5 . comparison of stresses and tensile strengths of concrete. here: σ xx are stresses caused by autogenous shrinkage of concrete; f ct(exp) is the tensile strength of concrete calculated from experimental compressive strength; σ i,a are the stresses obtained using the analitical method; σ i,s are the stresses obtained using the numerical method with program ansys the numerical problem solution allows to calculate the stress distribution around the transverse braces at any angle θ and the radius of the hole. numerical method obtained the stress distribution throughout the structure, which allows a better analysis of the construction work and predict crack growth. numerical method is more accurate and comprehensive as analytical method. it is obvious from the results obtained, that stresses three times as big as those impacting the member σ xx develop near the hole; they exceed the tensile strength of concrete within the first days of hardening. micro cracks appear at these locations even before the exploitation of the structural member begins. fig. 5. comparison of stresses and tensile strengths of concrete. here: σxx are stresses caused by autogenous shrinkage of concrete; fct(exp) is the tensile strength of concrete calculated from experimental compressive strength; σi,a are the stresses obtained using the analitical method; σi,s are the stresses obtained using the numerical method with program ansys the numerical problem solution allows to calculate the stress distribution around the transverse braces at any angle θ and the radius of the hole. numerical method obtained the stress distribution throughout the structure, which allows a better analysis of the construction work and predict crack growth. numerical method is more accurate and comprehensive as analytical method. it is obvious from the results obtained, that stresses three times as big as those impacting the member σxx develop near the hole; they exceed the tensile strength of concrete within the first days of hardening. micro cracks appear at these locations even before the exploitation of the structural member begins. after the removal of the formwork, total shrinkage strain due to drying starts developing; its limit value depends on the characteristics of the concrete structure and the surrounding environment. later, both the total shrinkage and stresses round the hole continue increasing, accompanied by the growth of the crack which can be noticed with the naked eye after the removal of the formwork . 4. conclusions 1. an area of stress concentration round the transverse bracing of the formwork, there the value of equivalent stresses is three times as big as the acting stresses appearing due to autogenous strains of concrete. the numerical problem solution allows calculate the stress distribution around the transverse braces at any angle θ and the radius of the hole. 2. the equivalent stresses exceed concrete’s tensile strength during the early days of concrete hardening and cause the opening of a crack. 3. to improve the quality of monolithic reinforced concrete structures as well as the reliability of exploitation, it is necessary to assess all the factors that influence strainstresses behavior: when concrete mix is poured, when it hardens inside the formwork, when the formwork is removed and during the subsequent stages of hardening at surrounding environment. references ansys, release 11.0. documentation for ansys. hansen w. 2011. report on 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[ decisions of construction technologies and estimation quality of kaunas biological wasterwater treatment plant. report of research work (contract no. 8364), kaunas university of technology] received 2012 06 11 accepted after revision 2012 09 03 antanas žiliukas – kaunas university of technology, strength and fracture mechanics centre. main research area: antanas žiliukas at the strength and fracture mechanics centre, kaunas university of technology. from 2000 a. žiliukas has been a director of strength and fracture mechanics centre. he has taken part in international projects related to the design of hydrogen aircraft engines and safety systems for nuclear power plants. the author of more than 20 books, and published over 100 articles. research interest materials mechanics, theory of elasticity and plasticity, fracture mechanics, theory of reliability to students at all levels. address: kęstučio st. 27, lt-44025 kaunas, lithuania. tel.: 8-37-300431 e-mail: antanas.ziliukas@ktu.lt giedrius žiogas – affiliation kaunas university of technology, strength and fracture mechanics centre. main research area: person maintaining a doctor’s thesis. msc (2009, civil engineer). strength and fracture mechanics centre at kaunas university of technology. research interests: fracture mechanics of reinforced concrete structures. address: kęstučio st. 27, lt-44025 kaunas, lithuania. tel.: +370 605 31996 e-mail: ziogas.giedrius@gmail.com 205 journal of sustainable architecture and civil engineering 2021/2/29 *corresponding author: 2002gsa@mail.ru the assessment features of noise pollution in the residential area of the subjects of the russian federation received 2021/04/28 accepted after revision 2021/09/02 the assessment features of noise pollution in the residential area of the subjects of the russian federation jsace 2/29 http://dx.doi.org/10.5755/j01.sace.29.2.29012 gagarin sergey aleksandrovich*, gagarina olga vyacheslavovna, semakina alsu valerievna, platunova guzel rashidovna, rubtsova irina yuryevna udmurt state university, universitetskaya ulitsa, 1/1, izhevsk, udmurt republic, russia journal of sustainable architecture and civil engineering vol. 2 / no. 29 / 2021 pp. 205-215 doi 10.5755/j01.sace.29.2.29012 introduction the distinctive features of the noise protection legislation at the level of 85 subjects of the russian federation are considered. the comparative characteristics of the time parameters “day”, “night” for working days and holidays are given. it is compared with similar indicators of other countries. 46% of subjects considered 7 am as the beginning of the “day” period; 61% considered 22 pm as the beginning of the "night" period. for the first time russia developed the following time periods separately: “day rest”, “evening”, “weekends and holidays”. the penalty system for violation of the noise legislation is analyzed. irkutsk region has the “smallest” fines in russia and novosibirsk and belgorod regions have the “biggest” fines. keywords: noise, law of silence, unreasonable noise, ruhezeiten, hausordnung. the negative impact of noise on human health is well known. numerous scientific publications of both medical and engineering fields are devoted to this topic. this article reveals the problem of noise pollution in the territory of long-term stay of a person, i.e. an apartment. apartment buildings, where the issues of the rules of public behavior are of particular importance, are described in the article. the legal aspects of the problem are considered. the purpose of this article is to conduct a comparative analysis of the regulations on noise exposure restrictions in apartment residential buildings of russia. table 1 presents the results of the noise exposure thresholds for human health based on the results of the expert working group from european regional bureau of the world health organization. in russia, the impact of intermittent noise is assessed by the maximum permissible levels (mpl) according to the equivalent and maximum indicators. table 2 presents the maximum permissible levels of the audible noise for the inner part of housing and the area adjacent to the residential building. journal of sustainable architecture and civil engineering 2021/2/29 206 table 1 effects with sufficient evidence and thresholds for their occurrence (night noise guidelines for europe, 2009) effect signs indicator threshold, db biological effects changes in the cardiovascular system * * restless sleep, fidgeting during sleep lamax,inside 32 changes in the duration of different sleep stages, sleep structure and sleep fragmentation lamax,inside 35 sleep quality waking up at night and / or very early in the morning lamax,inside 42 elongation of the falling asleep stage, difficulty in falling asleep * * sleep fragmentation, reduction of sleep time * * increase in the average level of fidgets during sleep lamax,inside 42 wellness feeling of sleep disturbance lamax,inside 42 use of sleeping pills and sedatives lamax,inside 40 diseases insomnia associated with environmental factors lamax,inside 42 when comparing the mpl values near the house space, the night laeq value in russia is 45 dba that is one of the minimum indicators in comparison with the eu member states (table 3). the main sources of acoustic pollution in residential apartment buildings are external and internal. external sources are primarily represented by traffic noise. the evening time of the day is characterized by a gradual decrease in the intensity of traffic flow; therefore, the contribution of automobile noise turns out to be less significant. at the same time, the maximum noise pressure levels from the loudest types of transport motorcycles are of great importance. the noise in the building space can be caused by car alarms, which, especially at night, causes a negative reaction from the residents. the internal sources of noise, first of all, include repair work inside apartments. loud music, holidays, and anniversaries are usually not regular and * this effect occurs or may occur when exposed to noise, indicators or thresholds cannot be determined. the impact of noise pollution on humans is estimated by several indicators (night noise guidelines for europe, 2009): lnight,outside average annual level of night noise outside buildings lamax maximum corrected noise level laeq – equivalent corrected noise level lamax,inside – maximum level of noise exposure in the bedroom lden – equivalent level of weighted average daily noise lnight – equivalent level of night noise. table 2 maximum permissible level of intermittent noise for accommodation area in russia (sp 2.2.4/2.1.8.562-96, 1997; sp 276.1325800.2016, 2017; snar 2.1.2.264510, 2010) purpose of premises time of day, h equivalent noise level laeq, dba maximum noise level laeq, dba living rooms of apartments in buildings of category a 7.00 – 23.00 35 50 23.00 – 7.00 25 40 living rooms of apartments in buildings of category b and c 7.00 – 23.00 40 55 23.00 – 7.00 30 45 areas directly adjacent to residential buildings, holiday homes, nursing homes for the elderly and disabled 7.00 – 23.00 55 70 23.00 – 7.00 45 60 table 3 country-defined maximum equivalent levels of lnight traffic noise in new residential areas (night noise guidelines for europe, 2009) eu member states lnight,outside france 62 germany 49 spain 45 netherlands 40 austria 50 sweden 51 finland 46 hungary 55 latvia 40 estonia 45 switzerland 50 207 journal of sustainable architecture and civil engineering 2021/2/29 are coordinated with neighbors. in contrast, the sound of working tools (perforator, electric drill and others) causes a sustained negative impact on the emotional state of neighbors. one of the objectives of this work is to quantify the noise pressure level of the indoor environment from the noise sources listed above. literature review the quantitative assessment of noise exposure to humans has a relatively recent history, dating back to 1956, when the ussr adopted the world's first occupational noise standards. the first uk noise abatement law was adopted in 1960 and continues to the present day. each country that has adopted a noise law has its own version, but at the same time they are united by: (ivanov, 2006) _ restrictions of various types of noise sources. _ prohibition of unnecessary redundant signals (for example, audio). _ system for issuing permits and certification of noisy work. _ procedure of verification, examination, and consideration of public complaints about noise sources. _ system of fines and compensations for violation of the law. the most economically developed countries adopted not only noise laws, but also applied aspects of assessing noise pollution. since 2000, several eu directives have been adopted: _ 2000/14/ec noise equipment for use outdoors (2000/14/ec, 2004) _ directive 2002/49/ec of the european parliament and of the council of the (european union directive 2002/49/ec, 2008) _ 2001/с 297/04 of the european parliament and of the council of 4 april 2001 on the approximation of the laws, regulations and administrative provisions of the member states relating to the implementation of good clinical practice in the conduct of clinical trials on medicinal products for human use (2001/с297/04, 2001) _ 2003/10/ес european directives on safety and health at work (2003/10/ес european directives, 2006) the world health organization has recommended guidelines for noise control: _ environmental noise guidelines for the european region, 2018 (environmental noise guidelines for the european region, 2007) _ environmental noise directive 2014, (night noise guidelines for europe, 2009) in russia, the basic principles of environmental protection from noise pollution are mentioned in the federal laws: _ "on environmental protection" 10.01.2002 no. 7-fl (as amended dd. 30.12.2020) _ "on the protection of atmospheric air" 04.05.1999 no. 96-fl (as amended dd. 08.12.2020) _ "on the sanitary and epidemiological well-being of the population" 30.03.1999 no. 52-fl (as amended dd. 13.07.2020). the actual material reflecting the quantitative indicators of noise pressure level regulation in places of human residence and time intervals is concentrated in other regulatory documents: sanitary standards (sp 2.2.4 / 2.1.8.562–96, 1997), building codes and regulations (snar 23-032003, 2003), codes of regulations (sp 276.1325800.2016, 2017; sp 271.1325800.2016, 2016; sp 51.13330.2011, 2011) state standards (gost 22283-88, 1988). another variable that characterizes noise standards in a residential area is the time range. taking into account the physiological need of a person for night rest, more stringent restrictions are proposed for this period. until 2003, there were uniform requirements in russia, according to which journal of sustainable architecture and civil engineering 2021/2/29 208 the daytime period began at 7 am and lasted until 11 pm (sp 2.2.4/2.1.8.562–96, 1997). in the eu states and other continents, differences occur not only in individual countries, but also in administrative divisions, including individual cities. a number of researchers in the eu countries use the global comfort index to assess the negative impact of noise levels on humans (luzzi et al, 2016, luzzi et al, 2019). in addition to the who guidelines (european union directive 2002/49/ec, 2008), it is proposed to take into account new pathologies and discomfort conditions associated with noise: sleep disorders, cognitive disorders, cardiovascular diseases, pregnancy complications. in addition to medical indications, the list of noise sources taken into account was expanded: it was proposed to additionally take into account the so – called "movida" the sound landscape of urban centers. this is the noise of leisure: concerts, discos, parties, etc., thereby justifying the right to rest. dietz t., stern p. (dietz t et al, 2008) propose to involve the interested party (the public) in environmental assessment and decision-making based on a five-stage procedure: information, consultation, involvement, cooperation, empowerment. a significant and large-scale project on the problems of sound insulation in urban residential buildings was the tu0901 project (rasmussen et al, 2014), which was attended by about 90 experts from 29 european countries. the acoustic assessment of buildings is based on their preliminary classification according to the functions performed in them: residential buildings, school buildings, office buildings and commercial buildings, hotels, hospitals and others. when considering the problems of noise pollution in apartment buildings, the following equipment was used: _ ekofizika-110a basic set-110a – 110a-noise meter, spectrum analyzer factory number ba16020. information on entering data into the federal information fund for ensuring the uniformity of measurements, entry number 68002222 (results of si. pct metrology verifications, 2021) _ larson-davis acoustic calibrator cal 200 model. the noise sources were: tools for indoor repair work (makita ga4530 angle grinder (98 db), makita hr2470x15 rotary hammer (105 db), crown st10127-13c impact – free drill (95 db); external noise sources-scher – khan m20 car alarm (100 db at a distance of 1 m), the noise of single motorcycles on deserted night roads honda cb500f road motorcycle when driving at a speed of 100-110 km/h (maximum sound pressure level of 105 dba at a distance of 7.5 m. modeling of acoustic pollution propagation was carried out using the ecolog-shum 2.4.6.6023 software module (developed by integral st. petersburg). materials and methods results of the study general characteristics of the legal regulation of noise exposure in the residential area of russia the main material for the analysis was the differences in the regulatory legal acts of the subjects of the russian federation, dedicated to the problems of noise in the area of human residence. the article considers 85 subjects located in different geographical conditions (from st. petersburg to primorsky territory), with different economic levels of development (from moscow to the khanty-mansiysk autonomous district), territories where worship services and other religious rites and ceremonies are performed within the framework of canonical requirements. "consultantplus" system helped to analyze legal documents of 85 subjects of the russian federation concerning measures of restrictions on excessive noise and measures of administrative influence of violators. the comparison was made based on 13 features that appear in the regional “laws of silence”. 47% out of 85 subjects of the russian federation have special legislation to protect against excessive noise inside housing and surrounding areas. in most cases, the law of silence regulates the 209 journal of sustainable architecture and civil engineering 2021/2/29 time interval for limiting excessive noise and the conditions for its application. in addition, in order to comply with the requirements in such a law, an administrative resource is required, which will be fulfilled with the help of system of fines and restrictions. as a rule, these are the laws "on administrative offenses ..." or "code of administrative offenses" for individual subjects. table 4 presents the main differences that are typical for the regulation of excessive noise in the subjects of the russian federation. table 4 time period of restrictions on excessive noise for the subjects of the russian federation (gagarin et al, 2020) time interval generalization notable differences weekdays day from 6-00 – 22% from 7-00 – 46% from 8-00 – 28% from 9-00 – 4% primorsky territory from 9–00 to 21-00 republic of mordovia from 6-00 to 23-00 lunch break (rest) from 12-00 – 2% from 13-00 – 32% none– 66% khabarovsk territory from 1300 to 15-00 on weekdays, fines are not imposed evening from 19-00 – 1% from 20-00 – 4% from 21-00 – 9% none – 86% repair and construction works are not carried out. night from 21-00 – 7% from 22-00 – 61% from 23-00 – 32% weekends and holidays day from 6-00 – 18% from 7-00 – 20% from 8-00 – 16% from 9-00 – 20% from 10-00 – 22% from 11-00 – 2% from 12-00 – 1% penza region friday and saturday according to the schedule from 6-00 to 23-00 magadan region silence mode from 21-00 to 11-00. night from 18-00 – 1% from 20-00 – 1% from 21-00 – 4% from 22-00 – 59% from 23-00 – 35% the repeatability of time intervals in the "laws of silence" showed that on working days of the week, the "day" period in most cases (46%) coincides with the all-russian period at 7-00. most regions of russia (61%) consider 22-00 as the beginning of the "night" period. for the first time, in russia, some subjects (45%) introduced restrictions on repair and construction work at lunchtime and in the evening. if the middle of the day coincides with a number of foreign countries (13-00 in 32% of russian regions), then the evening period for russia is mainly legally confirmed at 21-00, while in many countries this interval begins at 19-00. for weekends and holidays, the relative majority (59%) also considers 22-00 as the night period. while the beginning of the day has a significant range from 6-00 to 12-00, but 10-00 prevails, the repeatability of which was 22%. further we consider the legal component of the legislation "on silence". the main documents are special law, for example, "on ensuring peace and quiet of citizens in the territory of the samara region", "on ensuring peace and quiet of citizens on the territory of the udmurt republic" and similar ones. 47% of the considered subjects of the russian federation have such laws. other normative legal documents include the law "on administrative offenses", "code of administrative offenses" and others. the system of penalties for violating the silence regime is also noticeably different. most of the subjects have developed a punishment system that takes into account a more severe penalty for repeated violations. the minimum 300 rubles penalty for citizens is provided in the irkutsk region, the maximum 3500 rubles is in the belgorod region, the average is 1000 rubles in russia. officials are punished more severely: 500-1000 rubles in the irkutsk region, 25,000-50,000 rubles in st. petersburg, the national average 5,000-10,000 rubles. the highest amount of the fine is applied journal of sustainable architecture and civil engineering 2021/2/29 210 to legal entities: 1000-2000 rubles in the irkutsk region, 50,000-200,000 rubles in st. petersburg , the national average 15,000-20,000 rubles. the regulatory acts of the subjects of the russian federation provide for cases when it is allowed to temporarily exceed the level of permissible noise. there are generally accepted exceptions, for example, pyrotechnic actions during the new year celebrations, the prevention of offenses, the prevention and elimination of the consequences of accidents, natural disasters, and other emergencies, urgent work related to ensuring the personal and public safety of citizens in accordance with the legislation of the russian federation. the analysis of the regulatory documents of the subjects of the russian federation showed a discrepancy on a number of points: _ performing divine services, other religious rites, and ceremonies within the framework of the canonical requirements of the respective denominations. it is allowed to exceed the noise level. it is found in the legislation of 43% of the considered subjects of the russian federation. _ when carrying out cultural and sports events in accordance with the procedure established by the current legislation. it is allowed to exceed the noise level. it is found in the legislation of 17% of the considered subjects of the russian federation. requirements for the assessment of noise exposure in a residential area in other countries the formation of legislation to limit the noise load at the present stage originates in the uk with the adoption of the national law in 1960. this initiative was supported in other countries: united states (1972), netherlands (1979), france (1985), spain (1993) and denmark (1994), egypt (1994), etc. a number of countries have specific features, for example, australia, usa have the condition “unreasonable noise” that is the noise that is clearly heard from another apartment or room during protected hours and does not require confirmation by instrumental methods (usa, new jersey). in germany, there is the concept of ruhezeiten that is the time during which any noise is strictly prohibited. usually it is from 10:00 pm to 7:00 am the next day, but these rules can be changed at table 5 time period of excessive noise restrictions for different states. (european union directive 2002/49/ ec, 2008; night noise guidelines for europe, 2009; environmental noise guidelines for the european region, 2018; u.s. noise pollution and abatement act of 1972, 1972; shiro kawashima 1995, alice et al, 2019) country / state, city time interval workdays weekends and holidays “day” “night” “day” “night” germany 7-00 – 22-00 22-00 – 7-00 8-00 – 22-00 22-00 8-00 australia 7-00 – 22-00 22-00 – 7-00 9-00 – 22-00 22-00 9-00 finland 6-00 – 22-00 22-00 – 6-00 great britain 8-00 – 22-00 22-00 – 8-00 spain madrid 7-00 – 23-00 23-00 – 7-00 8-00 – 23-00 23-00 8-00 switzerland 8-00 – 22-00 22-00 – 8-00 italy 6-00 – 22-00 22-00 – 6-00 israel 7-00 – 20-00 20-00 – 7-00 7-00 – 17-00 17-00 7-00 china 8-00 – 21-00 21-00 – 8-00 india 8-00 – 22-00 22-00 – 8-00 sweden 7-00 – 22-00 22-00 – 7-00 poland 6-00 – 22-00 22-00 – 6-00 algeria 8-00 – 22-00 22-00 – 8-00 usa / florida 6-00 – 23-00 23-00 – 6-00 10-00 22-00 22-00 – 10-00 usa / georgia 7-00 – 22-00 22-00 – 7-00 the meeting of the house residents. the peoria, illinois noise act (sections 15-75 and 15-77) permits the seizure of vehicles that emit excessive sound caused by audio devices. standards of 14 countries were considered to compare the requirements for noise restrictions in the area of people's residence. when comparing the time intervals in tables 4 and 5, we conclude that there are no fundamental differences between the subjects of the russian federation and the countries under consideration. in russia, we can see a large amplitude in the time range of the beginning of the daily period – from 6-00 to 9-00. 211 journal of sustainable architecture and civil engineering 2021/2/29 modeling of acoustic wave propagation in the apartment building the instrumental equipment determines the characteristics of three types of noise sources: perforator, car alarm, and motorcycles driving at high speed at night. object noise pressure levels, db, in octave bands with geometric mean frequencies in hz laeq lamax measuring (calculation) distance r (m) 31.5 63 125 250 500 1000 2000 4000 8000 sources of constant noise perforator 1.0 99.0 102.0 107.0 104.0 101.0 101.0 98.0 92.0 91.0 105.0 sources of intermittent noise motorcycle 7.5 71.5 78.0 73.5 70.5 67.5 67.5 64.5 58.5 46.0 71.9 105.0 car alarm system 1.0 84.0 87.0 92.0 89.0 86.0 86.0 83.0 77.0 76.0 90.0 100.0 the ecolog-shum program was used to simulate the propagation of acoustic waves to the surrounding area. this is shown in fig. 1 and 2. the movement of noisy cars (motorcycles) at night is episodic and does not occur regularly, so only the maximum noise level was considered in the calculations. in the course of the experiment, the road section adjacent to the residential building at a distance of 23 meters was taken into account. the upper part of fig. 1 shows that at the level of the windows (closed), the lamax decreases to 90 db. double-glazed windows are practically not obstacle for acoustic waves, and for a short time the noise level in the living room reaches more than 85 db. in the lower part, the option of gradual attenuation of noise at a considerable distance is considered. more than 300 meters is necessary for the noise from high-speed riding of motorcycles to reach a level below 70 db. table 6 characteristics of noise sources fig. 1 propagation of the maximum noise level from the motorcycle (s) when driving at a speed of more than 100 km / h system the ecolog-shum program was used to simulate the propagation of acoustic waves to the surrounding area. this is shown in figures 1 and 2. the movement of noisy cars (motorcycles) at night is episodic and does not occur regularly, so only the maximum noise level was considered in the calculations. in the course of the experiment, the road section adjacent to the residential building at a distance of 23 meters was taken into account. the upper part of figure 1 shows that at the level of the windows (closed), the lamax decreases to 90 db. double-glazed windows are practically not obstacle for acoustic waves, and for a short time the noise level in the living room reaches more than 85 db. in the lower part, the option of gradual attenuation of noise at a considerable distance is considered. more than 300 meters is necessary for the noise from high-speed riding of motorcycles to reach a level below 70 db. figure 1 (figure 1). propagation of the maximum noise level from the motorcycle (s) when driving at a speed of more than 100 km / h a more frequent source of exposure to intra-neighborhood noise is car alarms. the option of placing a car in an open guest parking lot 12 meters away from an apartment building is considered. the initial noise intensity of 100 db, measured 1 meter away from the source, taking into account the short duration of the signal in the model and the spherical acoustic wave type, is considered as lamax 78 db. further to the window opening, it decreases to 60 db. in the case of an open window, the maximum noise level should not exceed 40 db (according to russian standards). figure 2 in the lower part shows that at a distance of 60 meters from the car, the permissible maximum noise level in front of the residential building is reached. with the windows open, this distance will be more than 300 meters to achieve a safe level of 40 db. a more frequent source of exposure to intra-neighborhood noise is car alarms. the option of placing a car in an open guest parking lot 12 meters away from an apartment building is considered. the initial noise intensity of 100 db, measured 1 meter away from the source, taking into account the short duration of the signal in the model and the spherical acoustic wave type, is considered as lamax 78 db. further to the window opening, it decreases to 60 db. in the case of an open window, journal of sustainable architecture and civil engineering 2021/2/29 212 the maximum noise level should not exceed 40 db (according to russian standards). fig. 2 in the lower part shows that at a distance of 60 meters from the car, the permissible maximum noise level in front of the residential building is reached. with the windows open, this distance will be more than 300 meters to achieve a safe level of 40 db. fig. 2 propagation of maximum noise level from car alarms figure 2 (figure 2). propagation of maximum noise level from car alarms the propagation of noise during repair work is not typical and depends on factors such as the area and volume of the room where the work is carried out, the reverberation time, the density and geometric dimensions of the obstacle wall. these conditions affect the sound insulation index rw, db, which in russia varies from 50 to 54 and depends on the category of the house. in the course of the experiment, the operation of perforator with an intensity of 105 db was considered. if we consider compliance with all technical standards when building a house, then even the minimum level on the opposite side will be at least 50 db of audible noise. table 2 presents that laeq is defined as 25 30 dba. discussions the european noise control guidelines provide thresholds for night noise levels in sleeping rooms (lamax, inside) and outside (lnight, outside). table 1 shows that “restlessness in sleep” and “micro-awakening” were the most sensitive indicators of noise exposure at night they constituted the threshold value lamax, inside 32 35 db. noise load requirements for russia are laeq 25 dba for high comfort houses of category a and laeq 30 dba for apartments with lower comfort level of category b (sp 2.2.4/2.1.8.562–96, 1997). these standards do not include office space toilet room, kitchen, and hallway. according to the guidelines (night noise guidelines for europe, 2009), noise in the area adjacent to residential buildings is responsible for the quality of sleep: “use of sleeping pills”, the propagation of noise during repair work is not typical and depends on factors such as the area and volume of the room where the work is carried out, the reverberation time, the density and geometric dimensions of the obstacle wall. these conditions affect the sound insulation index rw, db, which in russia varies from 50 to 54 and depends on the category of the house. in the course of the experiment, the operation of perforator with an intensity of 105 db was considered. if we consider compliance with all technical standards when building a house, then even the minimum level on the opposite side will be at least 50 db of audible noise. table 2 presents that laeq is defined as 25 30 dba. the european noise control guidelines provide thresholds for night noise levels in sleeping rooms (lamax, inside) and outside (lnight, outside). table 1 shows that “restlessness in sleep” and “micro-awakening” were the most sensitive indicators of noise exposure at night they constituted the threshold value lamax, inside 32 35 db. noise load requirements for russia are laeq 25 dba for high comfort houses of category a and laeq 30 dba for apartments with lower comfort level of category b (sp 2.2.4/2.1.8.562–96, 1997). these standards do not include office space toilet room, kitchen, and hallway. according to the guidelines (night noise guidelines for europe, 2009), noise in the area adjacent to residential buildings is responsible for the quality of sleep: “use of sleeping pills”, “sleep disturbance” “insomnia” the threshold value lnight, outside -40–42 db. taking into account, in most cases, the impossibility of observing such a strict criterion of the noise level, the members of the working group (night noise guidelines for europe, 2009) proposed 2 variants of the norms: the recommended level of night noise lnight, outside = 40 db and the intermediate target indicator lnight, outside = 55 db. most eu member states, except for france, have adopted this standard (see table 3). russia did not support the recommended level, but the adopted value of the night standard was significantly ahead of the target 45 dba. as mentioned earlier, the time intervals for restricting excessive noise for russia (subjects of the russian federation) and other countries are not fundamentally different. discussions 213 journal of sustainable architecture and civil engineering 2021/2/29 after the introduction of the" law of silence " in 40 subjects of the russian federation, the rights of residents in apartment buildings to favorable conditions have improved. the most effective mechanism in this case was the system of fines. it makes possible to influence the unauthorized actions of neighbors in the house, but weakly protects against excessive external noise. conclusionsproblems caused by excessive noise in places where people live are no less important than diffi-culties caused by occupational noise. if noise was originally considered as an effect of unavoidable human disturbance, then with the adoption of the first laws of silence since the 1970s, this issue has shifted from the field of psychology to a serious environmental problem. industrial noise is relatively easy to control and therefore can be regulated. significant difficulties arise with household noise. there are contradictions between the" freedom " of a person in private life and forced communication with neighbors. the solution to this problem currently lies in the area of improving legislation. in russia there is no federal law of noise now. there are sanitary standards, but they also differ in many federal subjects. it applies to the time interval for the action of standards in the periods: "day", "evening", "night". the physiological needs of a person suggest a duration of up to 10 hours (to ensure sleep protection for 80% of the population), but on average, people spend 7.5 hours in bed. (night noise guidelines for europe, 2009) for most countries and subjects of the russian federation, 15 16 hours are allotted for the night period of the day (due to the restrictions of external noise exposure). sanitary standards, taking into account the negative noise impact in russia, are confirmed by medical indications and correspond to similar requirements in other countries. the main problem is their compliance. if noise from neighbors can be regulated using administrative legislation (republics, regions, territories), then the impact of traffic noise at the moment is often an unsolvable problem. previously, the main types of sources of noise pollution in apartment buildings and the surrounding area were considered. reducing the severity of these problems found a solution in the legislative initiatives of some subjects of the russian federation, for example: _ within six months from the date of the cadastral registration of an apartment building, it is not allowed to carry out reconstruction, redevelopment, repair work (moscow region). _ turning off the sound signal of the triggered vehicle alarm daily and around the clock (nizhny novgorod region). _ failure by the driver or the owner (owner) of the vehicle to repeatedly (two or more times) triggered security alarm (samara region); _ construction works are not allowed, except for driving and vibrating piles, other work that creates noise above the permissible norm (samara region). _ performance of work, the suspension of which is impossible due to production and technical conditions (continuously operating organizations and individual entrepreneurs) (republic of dagestan). another problem related to household noise relates to the area of proving a violation of noise legislation. in russia, penalties can be applied if excessive noise is confirmed by an accredited laboratory, which is difficult to implement in practice. in this regard, the experience of the us state of new jersey is interesting when it is not required to invite a specialized laboratory. with regard to russia, this can be replaced by modern recording devices (for example, smartphone) with the participation of neighbors. it will also be effective to confiscate a vehicle by the municipal authorities if the residents of the house are often disturbed by car alarm, as in the us state of illinois. noteworthy is the experience of germany-ruhezeiten-house rules, when the residents of the house can clarify the rules of the internal order of residence. journal of sustainable architecture and civil engineering 2021/2/29 214 night noise guidelines for europe. copenhagen: who regional office for europe; 2009 207 с. directive 2002/49/ec of the european parliament and of the council of the european union of 25 june 2002 on the assessment and regulation of environmental noise. 2008 18 p. ivanov n.i. the problem of increased noise exposure to the population of the russian federation. proceedings of the conference "protection of the population from increased noise exposure: collection of reports of the scientific and practical conference with international participation. march 21-22, 2006 ", st. petersburg. edited by doctor of technical sciences, professor n.i. ivanova, doctor of medical sciences, professor k. b. fridman; baltic state university, st. petersburg, 2006-17-27 p. 2000/14/ec noise equipment for use outdoors. 2000 5 p. 2001/с 297/04 of the european parliament and of the council of 4 april 2001 10 p. 2003/10/ес european directives on safety and health at wor. 2003 4 p. environmental noise guidelines for the european region. copenhagen, 2018 181 p. сн 2.2.4 / 2.1.8.562-96 шум на рабочих местах, в помещениях жилых, общественных зданий и на территории жилой застройки [sp 2.2.4 / 2.1.8.56296 noise at workplaces, in premises of residential, public buildings and in the territory of residential development], ministry of health of russia, moscow, 1997. 8 p. снип 23-03-2003 защита от шума [snar 23-032003 noise protection], m, stroyizdat., 2003 .-52 p. гост 22283-88 шум авиационный [gost 2228388 aircraft noise. admissible noise levels in the region of dwelling-houses and methods of its measurement], m, 1990 17 p. сп 276.1325800.2016 здания и территории. правила проектирования защиты от шума транспортных потоков [sp 276.1325800.2016 buildings and territories. protection design rules from traffic noise], м, 2017 117 p. сп 271.1325800.2016. свод правил. системы шумоглушения воздушного отопления, вентиляции и кондиционирования воздуха. правила проектирования [cp 271.1325800.2016 noise reduction system of air heating, ventilating and air conditioning. rules of design], м, 20016 -65 p. сп 51.13330.2011 защита от шума [cp 51.13330.2011 sound protection], м, 2011 50 p. https://doi.org/10.1365/s35144-011-0017-6 санпин 2.1.2.2645-10 санитарно-эпидемиологические требования к условиям проживания в жилых зданиях и помещениях [snar 2.1.2.2645 sanitary and epidemiological requirements for living conditions in residential buildings and premises (as amended by snar 2.1.2.2801-10) luzzi, s. et al. environmental noise directive implementation: state of art, public participation and noise awareness. noise theory and practice 2, 2016. pp. 2-15. luzzi s., bartalucci c., di bella a. global comfort in urban planning and acoustic design of buildings. conference 2019. dietz t., stern p. «public participation in environmental assessment and decision making», national academies press. 2008 rasmussen b., machimbarrena m., cost action tu0901. building acoustics throughout europe: towards a common framework in building acoustics throughout europe 1, 2014, available at: http:// www.costtu0901.eu/tu0901-e-books.html. results of si. pct metrology verifications. url: https://fgis.gost.ru/fundmetrology/cm/results (date of access: 28.07.2021) s. a. gagarin, m. wage. правовое регулирование вредного физического воздействия на атмосферный воздух в виде шума в законодательстве субъектов российской федерации: сравнительный анализ [legal regulation of harmful physical effects on atmospheric air in the form of noise in the legislation of the subjects of the russian federation: сomparative analysis] // вестник удмуртского университета. сер. экономика и право. 2020. t. 30, no. 2. p. 249-255. u.s. noise pollution and abatement act of 1972, 1972 28 p. shiro kawashima, a survey of environmental law and policy in japan // north carolina journal of international law and commercial regulation. 1995. vol. 20. no. 2. pp. 232 272. alice h. suter. document from the ips "code. standards and rules. url: http://base.safework. ru/iloenc?print&nd=857100178. (date of access: 28.02.2021). references 215 journal of sustainable architecture and civil engineering 2021/2/29 gagarin sergey aleksandrovich senior lecturer udmurt state university, department of ecology and nature management main research area environmental pollution, acoustics address universitetskaya st. 1/1, izhevsk, udmurt republic, russia e-mail: 2002gsa@mail.ru gagarina olga vyacheslavovna candidate of geographical sciences, associate professor udmurt state university, department of ecology and nature management main research area mathematical modeling of natural processes universitetskaya street 1, izhevsk city 7+3412916433 e-mail: olgagagarina@mail.ru about the authors semakina alsu valerievna candidate of geographical sciences, associate professor udmurt state university, department of ecology and nature management main research area environmental mapping, atmospheric air pollution address universitetskaya st. 1/1, izhevsk, udmurt republic, russia e-mail: alsen13@list.ru platunova guzel rashidovna candidate of biological sciences, аssociate professor udmurt state university, department of ecology and nature management main research area hydrobiology. ecology, geobotany, soil science, hydrobotany, populations, biomorphologists address universitetskaya st. 1/1, izhevsk, udmurt republic, russia e-mail: dyukina-guzel@yandex.ru rubtsova irina yuryevna candidate of geographical sciences, associate professor udmurt state university, department of ecology and nature management main research area medical and environmental assessment of the territory, chemical and physical pollution of the environment address universitetskaya st. 1/1, izhevsk, udmurt republic, russia e-mail: irrubcov@mail.ru this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). journal of sustainable architecture and civil engineering 2023/1/32 224 use of blast furnace dust in the production of asphalt concrete for pavements, performance and environmental contribution received 2022/09/16 accepted after revision 2023/04/17 use of blast furnace dust in the production of asphalt concrete for pavements, performance and environmental contribution jsace 1/32 ricardo ochoa díaz* department of transportation and road engineering, faculty of engineering, pedagogical and technological university of colombia, tunja, colombia andrea pérez rojas faculty of engineering, university of manitoba, winnipeg, manitoba, canada gloria grimaldo león department of industrial engineering, faculty of engineering, university of boyacá, tunja, colombia *corresponding author: ricardo.ochoa@uptc.edu.co https://doi.org/10.5755/j01.sace.32.1.32300 journal of sustainable architecture and civil engineering vol. 1 / no. 32 / 2023 pp. 224-232 doi 10.5755/j01.sace.32.1.32300 abstract introduction this study analyzed the possible use of a residue from the steel industry, blast furnace dust, as aggregate in asphalt mixtures for pavements, as a possible solution to the problems of generation and accumulation of industrial waste in the production of steel, as well as the exploitation of non-renewable materials for infrastructure construction. in the production of steel, solid residues such as slag and blast furnace dust are generated, which become industrial waste. another found issue in pavement construction is the exploitation and use of stone materials are necessary. two test states were selected to achieve the established objective where blast furnace dust totally (100%) or partially (50%) replaced the conventional fine aggregate in an asphalt mixture at the laboratory. the applied methodology consisted of four stages: establishing the properties of the materials, determining the composition of the blast furnace dust, designing each of the mixtures using the ramcodes methodology, and finally performing performance tests such as dynamic modulus and fatigue laws. the results show an acceptable behavior of the blast furnace dust and allow to define that the use of this residue is technically feasible in manufacturing asphalt mixtures for pavements. keywords: blast furnace dust, asphalt mix, modulus, fatigue. blast furnace dust (bfd) is a residue from steelmaking in integrated steel mills. bfd is produced in the blast furnace during the smelting of ores (iron ore, limestone and coke) to produce pig iron. during this transformation, gases and particulate matter are generated that are recovered in the collectors.. (hu et al., 2017). in the only integrated steel company that exists in colombia, acerías paz del río s.a., approximately 7,200 tons of bfd are produced annually in most cases, due to its low use and storage in outdoor patios, this waste has negative environmental impacts. due to the above, the bfd is proposed as an alternative material in the construction of pavements, which in turn allows to face the shortage of natural stone aggregates of quality specifications for the construction of roads. 225 journal of sustainable architecture and civil engineering 2023/1/32 currently, there is a growing interest in using industrial waste as a component in asphalt mixtures, as it has been shown that the addition of some of these wastes significantly improves the mechanical properties of the mixture (pourtahmasb et al., 2015) (delongui et al., 2018), resulting in greater pavement durability. the steel industry is one of the main producers of solid waste globally, which has raised concerns about its environmental impact. however, some of these wastes have been demonstrated to be a sustainable and cost-effective alternative for asphalt mixture production (chen & wei, 2016). in addition, by-products such as slags, blast furnace dust, and others, have also been investigated as possible additions in asphalt mixtures. the incorporation of these wastes into asphalt mixtures can improve their mechanical properties, resulting in greater pavement durability (xie et al., 2017). therefore, the use of waste from the steel industry in asphalt mixtures is an attractive option from an economic and environmental perspective. however, there is very little information in the literature on the use of blast furnace dust (bfd) in asphalt mixtures for pavements. the purpose of this study is to analyze and evaluate the possibility of substituting the fine aggregate, in an asphalt mixture, by bfd, in two proportions: 50% and 100%, and to determine the behavior of the mixtures through the dynamic modulus and fatigue resistance. the experimental design consisted of manufacturing three types of mixtures using the void polygon concept of the ramcodes methodology (sánchez-leal et al., 2011) to determine the adequate content of asphalt cement: a control mixture with natural aggregates (m-0), a mixture substituting 50% of the fine aggregate with bfd (m-50), and a mixture substituting 100% with bfd (m-100). the mixtures were tested on void, stability, and flow parameters to verify compliance with local specifications (invias, 2013), and, finally, the dynamic modulus and fatigue resistance tests were carried out. all the results were compared and analyzed to establish the possibility of using bfd as a material in the manufacture of asphalt mixtures. fig. 1 (a) gravel-type coarse aggregate, (b) sand-type fine aggregate, (c) bfd fine aggregate materials and methodology this section exposes the conditions in which the analyzes and tests were carried out to investigate the behavior of asphalt mixtures with bfd as fine aggregate. as well as the origin and characteristics of the materials used. materials the materials used were natural stone aggregates, bfd, and 80/100 penetration asphalt cement. fig. 1 shows the materials used, conventional stone aggregates and blast furnace dust, which were supplied by the la roca quarry and votorantin-acerías paz del río s.a., respectively. the asphalt binder was supplied by the company incoasfaltos s.a.s. the type of asphalt mixture selected in the investigation was mdc-19 for an nt3 traffic level, following what is specified by colombia’s national roads institute (invias). (a) (b) (c) journal of sustainable architecture and civil engineering 2023/1/32 226 methodology the methodology comprises four organized and scheduled stages, each with its objectives and tasks to be carried out. initially carry out the necessary tests to know the physical-mechanical properties of the bfd and natural aggregates. test results were compared with the general road construction specifications in order to define material compliance or rejection for its use in asphalt concrete. the second stage consisted of carrying out the chemical characterization of the bfd: determination of the composition with the x-ray fluorescence equipment and the crystallographic structure in the x-ray diffractometer. the foregoing, to identify the predominant compounds of the bfd and establish the convenience of its use. risk-free use. in stage 3, the mixtures were designed in their material combinations and dosages using the ramcodes methodology (sánchez-leal, 2009). finally, in stage 4, the dynamic modulus and fatigue tests were carried out on each mixture with the working formula obtained. results were analyzed and thus, the mixture with the best characteristics and behavior was determined. dynamic module to determine the dynamic modulus, the indirect stress test was used, with the procedure of standard ne-12697-26-annex c (aenor, 2012a). three specimens were manufactured for each type of mixture and tested at 5°c, 25°c, and 40°c and a frequency of 10 hz, considering that the dynamic modulus is inversely proportional to the temperature, due to the viscoelastic behavior and the susceptibility of the asphalt cement to changes in temperature, when the temperature increases we will find lower modulus values. (pourtahmasb et al., 2015). with the results of the tests carried out and with the help of the least squares regression, a mathematical function of the type given (eq.1) is adjusted. e = a * eb *t (1) e is the modulus dynamic; t is the temperature of the mixture; a and b are regression constants (aenor, 2012b). fatigue the fatigue test was carried out by indirect traction according to standard bs-en-12697-24 annex e (aenor, 2008) under controlled stress since it has a better correspondence with the working conditions of the mix in the field (pasandín & pérez, 2017). the specimens were tested at a frequency of 2.5 hz and at a controlled temperature of 20 °c. for the test, eight specimens were manufactured with the optimal binder content and for each type of mixture. each group of specimens are divided into four groups, two specimens were tested at different load levels. the selected loads were in the range of 250 kpa to 350 kpa. for each briquette subjected to this test, the life until breakage was determined from the number of load applications that cause breakage. to find the fatigue laws in each type of mixture, whöler’s equation (eq.2) was used. εo = k (nf)-n (2) εo is the horizontal strain of initial tension in με, nf is the number of load cycles until fatigue failure and k and n are constants of the material. 227 journal of sustainable architecture and civil engineering 2023/1/32 results and analysis physical-mechanical characterization of the aggregates table 1 shows the results of the characteristics of the material used as coarse aggregate and table 2 shows the characteristics of the fine aggregates. the results found are compared with the values required for a traffic level of nt-3 and for a hot mix asphalt. the foregoing, considering the general road construction specifications of the national institute of roads invias. as seen in table 1, the material used as coarse aggregate meets the requirements established in the specifications. properties gravel requirements standard test l.a. abrasion, (%) 19.50 <25 astm c131 micro-deval abrasion (%) 19.80 <20 astm d6928 mechanical strength, 10% fine (kn) 122.80 >110 sabs meth 842 soundness na2so4 (%) 1.60 <18 astm c88 fractured particles (%) 94.10 >85 astm d 5821 gsa 2.76 gss 2.70 gsb 2.67 absorption (%) 1.20 astm c127/128 properties results requirements standard test sand bfd plasticity index (%) np np np astm d4318 sand equivalent (%) 68.00 93.80 >50 astm d2414 angularity (%) 46.80 53.00 >45 astm c1252 gsa 2.78 2.73 gss 2.74 2.50 gsb 2.72 2.36 absorption (%) 0.76 5.65 table 1 coarse aggregate characterization results table 2 fine material characterization results gsa: apparent specific gravity; gss: saturated and superficially dry gravity; gsb: bulk specific gravity results in table 2 show that bfd has a low specific gravity, high absorption, high sand equivalent, and high angularity compared to sand. the lower specific gravity influences the greater amount of bfd material necessary in the material dosage to obtain work granulometry. furthermore, its greater absorption is directly related to the greater amount of asphalt cement necessary in the asphalt concretes that use bfd as fine aggregate. chemical characterization of the aggregates table 3 shows the results of the x-ray fluorescence (xrf) essay for each of the aggregates. the main chemical compounds of coarse aggregate are cao, sio2, and al2o3. the main chemical component of the sand is sio2 (88.69%), while this same compound in bfd is only 5.51%. the main chemical constituent of bfd is fe2o3 (77.5%), while in sand, it’s only 0.99%. regarding the volumetric expansion of bfd, due to the low content of cao and mgo, it can be asserted that this material has a low probability of having expansive characteristics. the cao/sio2 ratio estimates the alkalinity level of the materials, according to (gao et al., 2017), alkalinity is classified into three degrees: low alkalinity (< 1.8), intermediate alkalinity (1.8 2.5), gsa: apparent specific gravity; gss: saturated and superficially dry gravity; gsb: bulk specific gravity journal of sustainable architecture and civil engineering 2023/1/32 228 component (% in weight) mgo al2o3 sio2 p2o5 cao mno fe2o3 otros gravel 3.80 9.30 16.60 63.40 0.17 3.04 3.63 sand 1.60 7.30 88.69 0.46 0.99 1.00 bfd 1.00 3.60 5.51 0.20 4.95 3.32 77.50 0.90 fig. 2 diffractogram for bfd table 3 chemical composition of aggregates in xrf and high alkalinity (> 2.5). intermediate or high alkalinities lead to a higher affinity between the asphalt cement and the aggregate (xie et al., 2012). gravel has a cao/sio2 ratio of 3.8, bfd has a 0.9 ratio, and sand has a ratio equal to 0.005. therefore, bfd has a better affinity with the asphalt binder than sand. fig. 2 shows bfd’s diffractogram. iron hydroxides (fe(oh)2) were found, so it is interpreted that the material was wet and had a reaction. there are also forsterite-type magnesium silicates (mg2sio4) generated at high temperatures, and calcium and aluminum silicates such as prehnite (ca2al(si3al)o10(oh)2) and goethite (α-fe 3+o(oh)), which is formed under oxidizing conditions as a product of the weathering of minerals containing iron, were also found. considering that the major chemical component of bfd is fe2o3, it can react with water and form a leachate that may be unfavorable to the environment. it can also have some reaction with cao and mgo, although the content of these components is low. however, it is necessary to further analyze these chemical reactions and establish their potential impact on the environment. mixture design the mixtures were designed under the ramcodes methodology premises, based on obtaining the optimum asphalt cement content with the void polygon. the void polygon is an analytical tool to determine the working formula for any hot-dense asphalt mixture based on the void specifications. the void parameters in an asphalt mix for both marshall and superpave are voids filled with asphalt (vfa), voids in mineral aggregate (vma), and air voids (va). these are analytically and graphically represented within a plane of density against asphalt content (sánchez-leal et al., 2011). table 4 compares the results of the base mix design (m-0) with the mix design with conventional coarse aggregate and with the incorporation of bfd as fine aggregate (m-50 and m-100). table 4 shows the increases in asphalt cement content as the bfd proportion increases, which 229 journal of sustainable architecture and civil engineering 2023/1/32 can be attributed to the bfd texture and porosity and ratified with the result of absorbed asphalt. the stability is higher than the minimum required in specifications but lower than the stability of the base mixture, which can be attributed to the shape and texture of the bfd rounded edges and the higher asphalt cement content in the mixtures. the volumetric properties and other characteristics are within the required range. m-0 mr = 29645e-0.109t r² = 0.984 m-50 mr = 13855e-0.083t r² = 0.9948 m-100 mr = 7256e-0.074t r² = 0.9987 100 1000 10000 100000 0 5 10 15 20 25 30 35 40 45 d yn am ic m od ul e (m pa ) temperature (°c) characteristic unit value requirements m-0 m-50 m-100 aggregate content % 95.20 95.10 95.50 asphalt content % 4.80 5.90 6.20 bulk specific gravity (gmb) g/cm 3 2.38 2.35 2.31 maximum specific gravity (gmm) g/cm 3 2.51 2.46 2.48 stability n 11967 9925 9548 9000 flow mm 3.34 3.01 3.00 2.0 – 3.5 stability/flow kn/mm 3.56 3.31 3.16 3.0 6.0 air voids (va) % 5.15 4.81 5.18 4.0 – 6.0 vam % 15.80 16.22 16.15 >15.0 vfa % 67.42 70.32 67.94 65 75 absorbed asphalt (pba) % 0.24 1.00 1.44 effective asphalt (pbe) % 4.57 4.96 4.85 filler/effective binder 1.10 1.00 1.00 0.8 – 1.2 table 4 results of the characterization and design of the mixtures fig. 3 dynamic modulus master curves dynamic module fig. 3 shows the dynamic modulus trend lines for each of the mixtures tested. mixes m-50 and m-100, which were manufactured with bfd in partial or total replacement of fine aggregate, show lower resilient moduli at 20°c than mix m-0, which did not use bfd. however, at high temperatures, the mixtures m-50 and m-100 present a dynamic modulus greater than the modulus of the control mixture m-0. this can be associated with the high production temperature of bfd, which makes this material capable of absorbing thermal energy and can increase the heat storage effect in asphalt concrete (huang et al., 2012). journal of sustainable architecture and civil engineering 2023/1/32 230 m-0 εo = 2333.3n-0.193 r² = 0.9234 m-50 εo = 1082.2n-0.101 r² = 0.903 m-100 εo = 2782.2n-0.241 r² = 0.9094 100 1000 500 5000 50000 in iti al s tr ai nl (µ ε) number of cycles until failure fig. 4 laws of fatigue for mixtures fatigue fatigue deterioration in asphalt mix layers is the most common deterioration. the test consists of determining the number of load repetitions until failure occurs (nf) and is associated with the ability of the mixture to withstand cyclic traffic loads (li et al., 2013). fig. 4 shows the effort against the number of cycles for the mixtures under study. in the same way, the equations of the fatigue law and the correlation coefficient are shown (r2), which indicates that there is a statistical correlation between the results obtained to determine each fatigue law, given that the r2 coefficients are greater than 0.80. the fatigue law with the greatest slope is the m-0 mixture. the slope of the m-50 mixture fatigue law is slightly less inclined than that of the m-100 mixture. consequently, the m-100 mixture has a better fatigue life for low stresses than the m-50 mixture. the inclusion of bfd in asphalt mixes can cause changes in the properties of the asphalt. the high alkalinity of bfd can affect the asphalt curing process, which can result in a reduction in the durability of the asphalt mix. however, the addition of bfd can also improve certain properties of asphalt mixes, such as resistance to deformation at high temperatures. additionally, the inclusion of bfd in asphalt mixes can improve the adhesion properties of tires to the pavement and the durability of the pavement. bfd can increase the surface texture of the asphalt mix, which can lead to better contact between the tires and the pavement and improved skid resistance. bfd can also improve the resistance to rutting of asphalt mixes, which can result in increased pavement durability and lower maintenance costs. conclusions due to bfd’s porous surface texture, the optimal content of asphalt cement in mixtures m-50 and m-100 was greater than the optimal content of control mixture m-0. the m-50 mix, in which bfd partially replaced the fine natural aggregate, increased by only 1.1% compared to the optimal content of the base mix. similarly, the m-100 mix, in which 100% bfd was used as fine aggregate, increased the optimum asphalt cement content by 1.5%. previous results are supported by the surface texture and the greater bfd absorption compared to sand absorption. the increase in asphalt cement content will be reflected in the cost of the mix. all the mixtures meet stability requirements, but bfd mixtures had lower values than the base mixture, although stability values for m-50 and m-100 mixtures are higher by 10.3% and 6.1. % with respect to the minimum required stability. the stability values for the m-50 mixture decreased by 17% and for the m-100 mixture by 20% compared to the base m-0 mixture. similarly, the flow 231 journal of sustainable architecture and civil engineering 2023/1/32 values in mixtures with bfd are lower than the flow value in the base mixture, however, still within the interval established in the requirement. considering that the stability of a mixture depends on the friction between the particles, which is related to the texture, shape, size and cohesion of the asphalt cement, and because natural coarse aggregate was used, the decrease in stability can be attributed to the increase in the optimal content of asphalt binder. the dynamic modules of bfd mixtures were lower than the modulus of the base mixture. in addition, the dynamic modulus of the mixture in which the fine natural aggregate was totally replaced by bfd (m-100) is lower than the mixture in which the natural aggregate (m-50) was partially replaced. the dynamic modulus decreased by 21.4% and 50.7% in the m-50 and m-100 mixtures, respectively, compared to the modulus of the base mixture. similarly, the value of the dynamic modulus of the m-100 mix showed a decrease of 37.3% compared to the m-50 mix. the dynamic modulus values will affect the structural design of the pavement. finally, the m-50 mix presented better fatigue behavior at lower strains than the conventional mix. as we increase the level of deformation, that is, at high deformations, the m-50 mixture has a shorter life. likewise, considering the number of load repetitions, the m-50 mixture will resist higher initial deformations. the m-100 mix has lower fatigue life at low strains compared to the m-50 mix and the base mix, while at high strains, the m-100 mix has better fatigue life than the m-50 mix and a little less than the base mix. analyzing the m-100 mixture and considering the number of load cycles, it will resist lower initial deformations than the base mixture and less than the m-50 mixture. considering the results, using bfd as a fine aggregate in asphalt mixtures is technically feasible. acceptable stability and adequate fatigue behavior are found with the incorporation of 50% bfd. similarly, with 50% of bfd, a behavior of the dynamic module similar to that of the base mixture is obtained. therefore, it can be established that the substitution of 50% of conventional aggregate bfd guarantees an adequate behavior of the asphalt mixture. technically, the use of bfd in the production of asphalt mixtures for pavements is feasible, but the most important contribution is that with the use of this residue, it contributes to environmental sustainability due to the fact that less exploitation and utilization of waste will be necessary natural materials. in addition, with the use of bfd, storage in yards and pollution caused in steel companies and in nearby towns are reduced. although it is evident that the analyzed properties did not show a significant improvement, it can be established that the use of bfd in asphalt mixtures is not detrimental to the behavior of the mixtures since they meet the requirements established in the standards and can contribute to the environmental impact generated by the exploitation of non-renewable stone materials and the reduction in the storage of low-utilization industrial waste. therefore, it is possible to use bfd in asphalt mixtures, however, further research on the subject is necessary. based on the research findings, the authors recommend further investigation into the use of bfd in asphalt mixtures on topics such as determining the optimal amount of blast furnace dust to be added to asphalt mixtures to achieve desired properties and minimize potential negative effects, durability and long-term performance of pavements containing blast furnace dust, including factors such as resistance to moisture damage and rutting, effects of the use of blast furnace dust on different types of asphalt mixtures and under different environmental conditions. as well as the topic related to the reactions of the chemical components of bfd with water, since it is impossible to avoid water contact with the pavement structure. acknowledgments the authors thank josé manuel sierra, director of the laboratory of materials and pavements of the school of transport and road engineering of the uptc. also, to incitema for the collaboration in carrying out the chemical characterization tests. to the companies: votorantin-acerías paz del río s.a, cantera la roca and incoasfaltos s.a.s., for the supply of materials. journal of sustainable architecture and civil engineering 2023/1/32 232 aenor. (2008). método de ensayo para mezclas bituminosas en calente. parte 24: resistencia a la fatiga. norma española, une-en 126. www.aenor.es aenor, a. e. de n. y certificación. (2012a). mezclas bituminosas. métodos de ensayo para mezclas bituminosas en caliente. parte 26: rigidez (une-en 1269726). www.aenor.es aenor, a. e. de n. y certificación. (2012b). mezclas bituminosas. métodos de ensayo para mezclas bituminosas en caliente. parte 26: rigidez (une-en 12697-26). chen, j. s., & wei, s. h. (2016). engineering properties and performance of asphalt mixtures incorporating steel slag. construction and building materials, 128, 148153. https://doi.org/10.1016/j.conbuildmat.2016.10.027 delongui, l., matuella, m., núñez, w. p., fedrigo, w., silva filho, l. c. p. da, & ceratti, j. a. p. 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(2009). manual de aplicación metodología de analísis y diseño de geomateriales compactados (ramcodes (ed.)). sánchez-leal, f. j., anguas, p. g., larreal, m., & valdés, d. b. l. (2011). polyvoids : analytical tool for superpave hma design. journal of materials in civil engineering, 23(8), 1129-1137. https://doi.org/10.1061/ (asce)mt.1943-5533.0000275 xie, j., wu, s., lin, j., cai, j., chen, z., & wei, w. (2012). recycling of basic oxygen furnace slag in asphalt mixture: material characterization & moisture damage investigation. construction and building materials, 36, 467474. https://doi.org/10.1016/j.conbuildmat.2012.06.023 xie, j., wu, s., zhang, l., xiao, y., liu, q., yang, c., & nie, s. (2017). material characterization and performance evaluation of asphalt mixture incorporating basic oxygen furnace slag (bof) sludge. construction and building materials, 147, 362-370. https://doi.org/10.1016/j.conbuildmat.2017.04.131 about the authors andrea pérez rojas researcher university of manitoba, association of professional engineers and geoscientists of manitoba main research area construction materials, materials science address winnipeg, monitoba, canada tel. +1(204)9622173 e-mail: ing.yasminandrera@gmail.com ricardo ochoa díaz professor pedagogical and technological university of colombia, department of transportation and road engineering main research area pavements, new materials, pavement management, asphalt mixtures, construction materials address north central avenue 39-115, colombia tel. +573138284131 e-mail: ricardo.ochoa@uptc.edu.co gloria grimaldo león professor university of boyacá, department of industrial engineering, faculty of engineering main research area project management, innovation, sustainability address carrera 2ª este no. 64 – 169, colombia tel. +573138284132 e-mail: gegrimaldo@uniboyaca.edu.co this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). journal of sustainable architecture and civil engineering 2021/1/28 80 *corresponding author: darius.pupeikis@ktu.lt possibilities of using building information model data in reinforcement processing plantreceived 2020/07/14 accepted after revision 2021/05/19 journal of sustainable architecture and civil engineering vol. 1 / no. 28 / 2021 pp. 80-93 doi 10.5755/j01.sace.28.1.27593 possibilities of using building information model data in reinforcement processing plant jsace 1/28 http://dx.doi.org/10.5755/j01.sace.28.1.27593 darius pupeikis* mindaugas daukšys, arūnas aleksandras navickas kaunas university of technology, faculty of civil engineering and architecture, studentų st. 48, lt-51367 kaunas, lithuania lina morkūnaitė aalborg university, department of built environment, thomas manns vej 23, 9220 aalborg ø, denmark svajūnas abromas jsc “serfas”, technikos str. 7c, lt-51209 kaunas, lithuania introduction while the aec industry is moving towards digitalization off-site rebar prefabrication became a common practice. now most companies use a long-established standard order processing method, where the customer submits 2d paper or pdf-based drawings. subsequently, the manufacturers are obligated to make additional detailing, redrawing, calculations, and preparation of other required information for manufacturing. thus, in this typical scenario, there is a great repetition of the same tasks, with the obvious loss of time and increased likelihood of human error. however, improvements can be made by the application of advanced digital production workflow and the use of open bim standards (e.g., ifc, xml, bvbs). therefore, this paper presents the typical data flow algorithm in contrast to the automated data flow for reinforcement manufacturing. further, the two approaches are compared and analyzed based on multi-criteria decision making (mcdm) methods. the results have shown promising prospects for companies willing to automate their data flow processes by the use of 3d drawings and digital data from the bim model in their plants. keywords: bvbs, ifc, machine-readable data, reinforcement. building information modelling (bim) technologies are meant to facilitate not only design but also all the life-cycle stages of the project. thus, the use of production raw materials and time to manufacture final products can be optimized by using bim data. to reach this goal, the producers of construction raw materials need to build their product libraries (hamid et al., 2018) using machine-readable data standards intended for the whole supply chain (zhong et al., 2017). this would allow the manufacturers to link their products to the price, pre-inspection (martinez et al., 2019), sustainability factors, technical specifications, etc. in that way, the customers could immediately get information on how much the specific construction products would cost or technically influence the project. this will save the customers and manufacturers time to bid, make decisions or solve issues (maciel and corrêa 2017). using information from the bim platform, the customers could receive their orders much faster and with less chance of error (xu et al., 2020). 81 journal of sustainable architecture and civil engineering 2021/1/28 however, the shift to using bim in manufacturing requires additional training of personnel and the recruitment of new specialists to perform programming of the production equipment and customization of bim data (piroozfar et al., 2019, ignatova et al., 2018). also, companies need to upgrade their manufacturing equipment to be able to take full advantage of bim capabilities (abanda et al., 2017, lee et al., 2019). though, following the experience of other countries, it is highly recommended to introduce bim into manufacturing (wang et al., 2018), as in the future, plants that are incapable to work innovatively, will start to lose orders and customers. there are many ways how bim technology could facilitate manufacturing. yet, the main benefits come from the 3d model and the possibility to automatically generate 2d drawings, which are more detailed and gives a complete view of the designed products (nath et al., 2015, cho et al., 2014, yanga et al., 2020). that being said, 3d models help to reduce errors during product assembly while saving time and cost (yuan et al., 2018). to ensure the usability of bim, it is significant to analyze the data standards compatible with manufacturing machinery (liu et al., 2021, kouhestani and nik-bakht 2020), such as bvbs (bundesvereinigung der bausoftware), xml, or ifc (industry foundation classes). the bvbs standard is widely used for cnc (computer numerically controlled) bending and cutting machines, and it is a 2 item description: 8040 mm total length with two 90 °hooks with a bending diameter of 50 mm, and the length at each end is 2290 mm. bvbs data string: bf2d@hj@runset@iunset@p1@l8040,00@n1@e7,13@d12,00@gb500c@s50,00@v@a@gl2290 @w0@r46@w90@l3320@w0@r46@w90@l2290@w0@c70@ decodification: bf2d: two-dimensional rebar; hj: name of the project; p1: position number; l8040,00: cutting length, [mm]; i: index of respective drawing; n1: number of rebars; e7,13: weight of the bar, [kg]; d12,00: bar diameter, [mm]; gb500nc: steel grade; s50: bending diameter, [mm]; a: layer; gl2290: length at each end, [mm]; r46: assembly position. fig. 1 an example of the bvbs data string of the corresponding item. adapted from (jalali, 2018) fig. 2 the workflow of ifc and bvbs associated with the required information. adapted from (jalali, 2018) journal of sustainable architecture and civil engineering 2021/1/28 82 european standard equipment provider (bvbs – guidelines, 2000). this standard assists the exchange of information between rebar detailing software and cnc bending machines or pps (production planning and scheduling) software without manual intervention. the reinforcement data is exchanged through an ascii (american standard code for information interchange) encoded text file and, as other cad-cam (computer-aided design computer-aided manufacturing) formats like bvbs which is based on 2d drawings (maciel and corrêa, 2016). jalali (2018) in her research presented an example of bvbs data string of corresponding item (fig. 1). the workflow of 3d reinforcement production can be executed in both, ifc or bvbs format. the required information associated with each of the workflows is illustrated in fig. 2. table 1 ifc-based interoperability capabilities of the reviewed bim software tools. adapted from (aram et al 2013b) ifc-based interoperability structural design & analysis detailing scia eng. allplan precast bentley proconcrete tekla structures single rebar elements (geometric representation — ifc entity mapping) extruded & faceted brep — ifcreinforcingbar extruded & faceted brep — ifcreinforcingbar extruded — ifcreinforcingbar (only export) extruded — ifcreinforcingbar rebar groups and assemblies (geometric representation — ifc entity mapping) no extruded & faceted brep — ifcreinforcingbar extruded — ifcreinforcingbar (only export) faceted brep — ifcreinforcingbar mesh (geometric representation — ifc entity mapping) extruded & faceted brep — ifcreinforcingmesh extruded & faceted brep — ifcreinforcingmesh no faceted brep — ifcreinforcingbar rebar basic attributes including name, type, geometry type, ifc guid, bim tool’s guid, location, quantity & volume yes (all) yes (all) yes (all) yes (all) rebar structural attributes length, grade, & bar diameter length, grade, bar diameter & mark number rebar grade, bar diameter, surface attributes & gross/ net cross-section area length, grade, & bar diameter, shape number, hook angle, gross/net weight & gross/net cross section area number of individual rebars in an assembly like a cage or mesh no no no no rebar subassembly attributes (e.g., a group of stirrups in a cage) no all basic attributes as well as length, grade, & size, shape number all basic attributes as well as grade, bar diameter & surface attributes all basic attributes as well as length, grade, bar diameter & shape number according to buildingsmart (2012), the ifc geometric kernel offers three major representation types for solid models including swept solid, brep (boundary representation), and csg (construc83 journal of sustainable architecture and civil engineering 2021/1/28 methodology tion solid geometry). while the support of faceted brep is important to enable clash detection, exported reinforcement models that use faceted brep do not support further geometric detailing of a model as well as identification or editing of an element’s features and increase the model size. aram et al. (2013a) in their work analyzed reinforcement products’ ifc modeling workflows, information creation, and exchange practices during design, manufacturing, and installation phases. based on the results some recommendations were presented. for example, for metadata, the name and description should be provided at the type and assembly level. since one defined type can be used in different locations of a project modeled by different people, owner history should be defined either in the instance level or assembly of identical elements. for geometric representation: (a) extruded solid models through ifcsweptdisksolid (or its subtype ifcsweptdisksolidpolygonal) are recommended; (b) should be defined in the type level, so elements with identical geometry will share one geometric representation. for material definition: (a) should be defined in the type level, (b) in the detailing stage of a project, a material profile should be defined using ifcmaterialprofileset. autodesk revit structure has not yet implemented the ifc schema for reinforcement. according to aram et. al. (2013b) the three detailing software packages (allplan engineering, tekla structures, and bentley proconcrete) as well as scia engineer export some level of reinforcement information through the ifc (table 1). further, in this study, we present two types of manufacturing workflows for construction reinforcement products. the main purpose of this work is to compare the standard (currently used) method in contrast to the proposed digital order fulfillment method and to determine how digital processes facilitate the acquisition of information from work projects during the construction product manufacturing phase. the literature review has revealed that to understand the prospects of bim data use for the production of reinforcement products, it is useful to analyze two types of processing workflows (fig. 3): typical (a) and advanced (b). the typical workflow is based only on human-readable, usually paper-based drawings and corresponding information. furthermore, this production information is typically distributed across the various industry stakeholders. the second one is the advanced workflow method, which relies on the 3d model, and in a perfect case is enriched with attributes. in this study the two algorithms for factory-based reinforcement production represented in fig. 3 were analyzed and put into comparison based on five evaluative criteria: _ k1 – performance, efficiency (production unit per time). the optimization direction is to maximize the criterion. _ k2 – environmental impact (raw materials and energy consumption, waste management). the optimization direction is to minimize the criterion. _ k3 – investments (capital expenditure of hardware and software, machinery, tools, etc.). the optimization direction is to minimize the criterion. _ k4 – training (periodical improvement of employee’s competencies). the optimization direction is to minimize the criterion. _ k5 – quality assurance (reduction of errors). the optimization direction is to maximize the criterion. _ the priority ranking and significance of the evaluation criteria, which could define the choice of digital workflows, were determined using an expert pairwise comparison method adapted from duleba & moslem (2018). subsequently, the two workflow alternativestypical (a1) and advanced (a2) were compared using multicriteria decision making method (mcdm) topsis journal of sustainable architecture and civil engineering 2021/1/28 84 fig. 3 the typical (a) and advanced (b) digital workflows at the reinforcement processing plant . (technique for order preference by similarity to an ideal solution) combined with fuzzy numbers (fn) (nădăban et al., 2016). during the analysis, the evaluation criteria were rated based on linguistic terms by three experts and converted to fn according to triangular distribution. next, the criteria were recalculated in reflection to optimization direction and multiplied by the criteria weights established by the expert pairwise comparison method. finally, the fuzzy positive ideal solution (fpis) and fuzzy negative ideal solution (fnis) were calculated and the distance to each of them found. based on that the closeness coefficient (cc) was established allowing to rank the alternatives in descending order from 1 to 0. 85 journal of sustainable architecture and civil engineering 2021/1/28 the typical workflow starts with the customer placing an order. in this case, the manufacturer receives data in paper-like formats as .pdf, .doc, table-like .xls (not spreadsheet), non-vectorized drawings in .jpg or .pdf, 2d vectorized .dwg, .dxf, etc. subsequently, the received data has to be initially checked for accuracy. as the data is non-readable by machine, only manual data validation and integration is possible, which is a time-consuming and error-prone process. after initial checking of data, the process splits into two parallel processes: the extraction of required quantities for ordering raw materials and generation of detailed technical drawings needed for production machines. at this stage, human intervention is necessary as well, due to the lack of common standards in the manufacturing and construction industries. according to the detailed technical drawings, manufacturing technology sequence, equipment, etc., production planning and distribution of tasks are the next steps in a typical scenario. during a production process, quality inspections are common practice. in this case, quality inspectors are checking product and process-oriented qualitative and quantitative parameters, by measuring, monitoring, and comparing parameters with the design. it takes additional human recourses to check, compare, evaluate and analyze information from distributed sources. finally, when the production process goes to the end, labeling, ce marking, and preparation for logistics are necessary to consider. labeling and ce marking are closely related to collecting information from distributed sources: detailed design, order, document management system, erp (enterprise resource planning) system, etc. logistics strategy is relevant for rational cargo load ratio and “just in time” delivery for the customer. the right side of fig. 3 represents an advanced digital workflow based on machine-readable data and bim technology provided possibilities. nowadays, more and more projects are carried out by applying bim use cases. therefore, the amount of object-based, machine-readable attribute data is raising significantly. this creates a possibility to optimize processes, increase quality, and efficiency. in an advanced way, the customer is delivering orders based on open or proprietary bim or gis data standards. the most widely adopted open standards are the industry foundation classes (ifc) for building industry, bvbs for reinforcement industry, landxml (land extensible markup language) for the infrastructure industry, and citygml (city geographic markup language) for cities and built environment in general. proprietary data standards are more difficult to distinguish because there are a wide variety of software packages intended for bim and gis. some examples of proprietary data standards relevant for digital representation of reinforcement could be .db1 (tekla structures) or .rvt (revit). in the case of the advanced workflow, data standards need to be machine-readable and open, to enable effective data exchange, ensure a smooth validation process and automate/semi-automate other processes. this kind of approach opens the possibility to validate the orders, technical design, data about structures, etc. in an innovative and less error-prone way. to do so rules need to be created which later should be coded, e.g., in xml language and ran through checking algorithms or intended software. another important advantage is related to a quantity take-off operation for ordering and controlling necessary raw materials – bom (bill of materials). however, the preparation of appropriate data for direct upload to manufacturing equipment (cnc machines, robotic hand machine tools, plasma cutters, etc.) is one of the most critical steps. from the perspective of the machine’s data controller, more suitable are open data standards. distribution of manufacturing tasks, processes scheduling, controlling, and monitoring could be done more effectively while using machine-readable data. in terms of quality control, digital data creates an opportunity to change controlling from man-made to sensor-based and semi-automated approaches. the next steps in an advanced digital workflow are related to digital labeling, ce, and coc (certificate of conformance) marking, which especially becomes relevant in a wider bim approach. all construction products must have “digital passports” with the required information about their properties, use possibilities, maintenance, etc. in the case of logistics, the product’s 3d model provides valuable information and creates a possibility to arrange products in particular transport. typical and advanced digital workflows intended for the production of reinfor cement products journal of sustainable architecture and civil engineering 2021/1/28 86 criteria k1 k2 k3 k4 k5 si qi the priority ranking k1 3 3 3 3 12 0.400 1 k2 0 0 2 3 5 0.167 3 k3 0 3 3 2 8 0.267 2 k4 0 1 0 3 4 0.133 4 k5 0 1 0 0 1 0.033 5 total 30 1.00 the priority ranking and importance of the criteria the priority ranking and importance of the criteria resulting from the authors’ subjective opinions are given in table 2. the essence of the expert pairwise comparison method is that all criteria are compared with each other in pairs based on experts’ opinions (duleba & moslem, 2018). if option xi is better than option xj, it is given as “1” and xj as “0”. each evaluation criterion was scored according to the authors’ subjective opinion. each expert fills in the comparison data into paired comparison matrices. after that total pairwise comparison matrix of all experts’ subjective opinions is constructed (table 2). the significance of the criteria is determined by calculating the sum of the lines of each i the variant given in table 2 according to equation (1): 8 (1) the higher the si value, the more efficient the option or the more significant the criterion. the determined priority ranking was as follow: ; (2) there: qi – the subjective significance of criteria. note: when qi < 5%, the latter can be eliminated from further calculations. after that matrix transformation is performed to calculate the kendall concordance coefficient (table 3). table 3. the total transformed pairwise comparison matrix criteria k1 k3 k2 k4 k5 k1 3 3 3 3 k3 0 3 3 2 k2 0 0 2 3 k4 0 0 1 3 k5 0 0 1 0 after performing the calculations, it is necessary to check the kendall concordance coefficient – whether the opinions of the experts coincide (duleba & moslem, 2018). the kendall concordance coefficient was calculated according to equation (3): (3) there: m – number of experts; n – is the number of alternatives being compared; – possible combinations according to experts; – possible combinations according to evaluation criteria; – possible combinations according to reasons; – possible combinations according to experts. the concordance coefficient (w) was obtained equal to 0.87. as it is higher than 0.6, according to kendall’s agreement degree scale (m. g. kendall & b. babington smith, 1939) represented in table 4 it means that expert opinions agree, so the obtained data can be used in further calculations. table 4. kendall’s w agreement degree scale. w interpretation 0 no agreement 0.10 week agreement 0.30 moderate agreement 0.60 strong agreement 1 perfect agreement å = = n k iki xs 1 * . 54231 qqqqq >>>> ( ) ( ) ; 11 4 22 , * , 2* -÷÷ ø ö çç è æ ×+= åå nnmm ccxmx w nm ki ik ki ik 2 mc 2 nc b nc b mc (1) the higher the si value, the more efficient the option or the more significant the criterion. the determined priority ranking was as follow: ; 54231 qqqqq >>>> (2) there: qi – the subjective significance of criteria. note: when qi < 5%, the latter can be eliminated from further calculations. after that matrix transformation is performed to calculate the kendall concordance coefficient (table 3). table 2 the total pairwise comparison matrix table 3 the total transformed pairwise comparison matrix criteria k1 k3 k2 k4 k5 k1 3 3 3 3 k3 0 3 3 2 k2 0 0 2 3 k4 0 0 1 3 k5 0 0 1 0 after performing the calculations, it is necessary to check the kendall concordance coefficient – whether the opinions of the experts coincide (duleba & moslem, 2018). the kendall concordance coefficient was calculated according to equation (3): ( ) ( ) ; 11 4 22 , * , 2* -÷÷ ø ö çç è æ ×+= åå nnmm ccxmx w nm ki ik ki ik (3) 87 journal of sustainable architecture and civil engineering 2021/1/28 table 4 kendall’s w agreement degree scale w interpretation 0 no agreement 0.10 week agreement 0.30 moderate agreement 0.60 strong agreement 1 perfect agreement there: m – number of experts; n – is the number of alternatives being compared; 8 2 mc – possible combinations according to experts; 2 nc – possible combinations according to evaluation criteria; b nc – possible combinations according to reasons; b mc – possible combinations according to experts. workflow comparison based on fuzzy variables table 5 fuzzy preference scale table 6 expert ratings converted to fn linguistic term triangular fn very low (1,1,3) low (1,3,5) average (3,5,7) high (5,7,9) very high (7,9,9) expert 1 k1 k2 k3 k4 k5 a1 (3,5,7) (5,7,9) (1,3,5) (3,5,7) (1,1,3) a2 (7,9,9) (1,3,5) (5,7,9) (5,7,9) (5,7,9) expert 2 k1 k2 k3 k4 k5 a1 (1,3,5) (5,7,9) (1,3,5) (3,5,7) (1,1,3) a2 (7,9,9) (1,3,5) (5,7,9) (5,7,9) (7,9,9) expert 3 k1 k2 k3 k4 k5 a1 (3,5,7) (5,7,9) (1,3,5) (3,5,7) (1,1,3) a2 (7,9,9) (1,3,5) (5,7,9) (5,7,9) (7,9,9) the concordance coefficient (w) was obtained equal to 0.87. as it is higher than 0.6, according to kendall’s agreement degree scale (m. g. kendall & b. babington smith, 1939) represented in table 4 it means that expert opinions agree, so the obtained data can be used in further calculations. five criteria were chosen to compare the typical and advanced data flow algorithms. even though all of the criteria could be evaluated in numerical expressions (efficiencyproduct unit per time; investments-expenditures on new equipment/specialists/training; etc.) for the typical workflow, it is only possible to predict the variables for the advanced workflow, as it is still technically not implemented. therefore, to be able to achieve such comparison fuzzy linguistic variables are introduced. according to nădăban et al. (2016) in real-world situations often there some constraints, objectives, or consequences which cannot be accurately evaluated based on numerical expressions. therefore, linguistic fuzzy variables with assigned respective weights can assist in mcdm methods. fuzzy numbers (fn) are represented as a function commonly used in triangular, trapezoidal, or gaussian shapes. in this study, we have used the triangular distribution of fn combined with the mcdm topsis (technique for order preference by similarity to an ideal solution). topsis is one of the most used mcdm methods which aims at establishing the shortest distance for a chosen alternative to the positive alternative solution (pis) and farthest distance to the negative alternative solution (nis). there are eight main steps while performing fuzzy topsis analysis (nădăban et al., 2016): step 1. assignment rating to the criteria and the alternatives. three experts have weighted the typical (alternative-a1) and advanced (alternative-a2) workflows against five evaluation criteria based on fuzzy variables presented in table 5. subsequently, based on the fuzzy preference scale the recorded linguistic results were converted to fn (table 6). step 2. compute the aggregated fuzzy ratings for alternatives. in accordance with the experts ratings aggregated fuzzy ratings 𝑥𝑥" = $𝑎𝑎!", 𝑏𝑏!", 𝑐𝑐!") journal of sustainable architecture and civil engineering 2021/1/28 88 table 7 aggregated fuzzy ratings k1 k2 k3 k4 k5 a1 (1,4.33,7) (5,7,9) (1,3,5) (3,5,7) (1,2.33,5) a2 (7,9,9) (1,3,5) (5,7,9) (5,7,9) (5,8.33,9) table 8 normalized fuzzy decision matrix table 9 weighted normalized decision matrix are calculated based on the equation (4): 𝑎𝑎!" = min # -𝑎𝑎!" # . , 𝑏𝑏!" = $ % / 𝑏𝑏!" # % #&$ , 𝑐𝑐!" = max # -𝑐𝑐!" # .. (4) the results of the combined expert decision matrix are represented in table 7. k1 k2 k3 k4 k5 direction max min min min max a1 (0.11,0.48,0.78) (0.11,0.14,0.20) (0.20,0.33,1.00) (0.43,0.60,1.00) (0.11,0.26,0.56) a2 (0.78,1.00,1.00) (0.20,0.33,1.00) (0.11,0.14,0.20) (0.33,0.43,0.60) (0.56,0.93,1.00) step 3. compute the normalized fuzzy decision matrix. the normalized fuzzy decision matrix is calculated based on equations (5) or (6): 10 for maximized criteria �̃�𝑟!" = 9 '!" (" ∗ , )!" (" ∗ , (!" (" ∗ : and 𝑐𝑐" ∗ = max ! -𝑐𝑐!". fpis and fnis are calculated based on equations (7) and (8): 𝐴𝐴∗ = (𝑣𝑣"$∗, 𝑣𝑣",∗, … , 𝑣𝑣"-∗), 𝑤𝑤ℎ𝑒𝑒𝑟𝑟𝑒𝑒 𝑣𝑣"" ∗ = max ! -𝑣𝑣!".. (7) 𝐴𝐴+ = (𝑣𝑣"$+, 𝑣𝑣",+, … , 𝑣𝑣"-+), 𝑤𝑤ℎ𝑒𝑒𝑟𝑟𝑒𝑒 𝑣𝑣"" + = min ! -𝑣𝑣!"$. (8) the computed fpis and fnis values for each criterion are represented in table 10. table 10. fpis and fnis values k1 k2 k3 k4 k5 a* (0.04,0.19,0.31) (0.02,0.02,0.03) (0.05,0.09,0.27) (0.06,0.08,0.13) (0.00,0.01,0.02) a(0.31,0.40,0.40) (0.03,0.06,0.17) (0.03,0.04,0.05) (0.04,0.06,0.08) (0.02,0.03,0.03) step 6. compute the distance from each alternative to the fpis and the fnis. the distance from each alternative ai to the fpis and fnis is calculated according to respective equations (9) or (10): 𝑑𝑑!∗ = / 𝑑𝑑$𝑣𝑣"!", 𝑣𝑣""∗) "&$ (9) (5) 10 for minimized criteria �̃�𝑟!" = 9 '" $ (!" , '" $ )!" , '" $ '!" : and 𝑎𝑎" + = max ! -𝑎𝑎!". s wight of the criteria qi given in table 2. the results of the weighted normalized decision matrix are represented in table 9. table 9. weighted normalized decision matrix k1 k2 k3 k4 k5 weight 0.4 0.167 0.267 0.133 0.033 a1 (0.04,0.19,0.31) (0.02,0.02,0.03) (0.05,0.09,0.27) (0.06,0.08,0.13) (0.00,0.01,0.02) a2 (0.31,0.40,0.40) (0.03,0.06,0.17) (0.03,0.04,0.05) (0.04,0.06,0.08) (0.02,0.03,0.03) step 5. compute the fuzzy positive ideal solution (fpis) and fuzzy negative ideal solution (fnis). fpis and fnis are calculated based on equations (7) and (8): 𝐴𝐴∗ = (𝑣𝑣"$∗, 𝑣𝑣",∗, … , 𝑣𝑣"-∗), 𝑤𝑤ℎ𝑒𝑒𝑟𝑟𝑒𝑒 𝑣𝑣"" ∗ = max ! -𝑣𝑣!".. (7) 𝐴𝐴+ = (𝑣𝑣"$+, 𝑣𝑣",+, … , 𝑣𝑣"-+), 𝑤𝑤ℎ𝑒𝑒𝑟𝑟𝑒𝑒 𝑣𝑣"" + = min ! -𝑣𝑣!"$. (8) the computed fpis and fnis values for each criterion are represented in table 10. table 10. fpis and fnis values k1 k2 k3 k4 k5 a* (0.04,0.19,0.31) (0.02,0.02,0.03) (0.05,0.09,0.27) (0.06,0.08,0.13) (0.00,0.01,0.02) a(0.31,0.40,0.40) (0.03,0.06,0.17) (0.03,0.04,0.05) (0.04,0.06,0.08) (0.02,0.03,0.03) step 6. compute the distance from each alternative to the fpis and the fnis. the distance from each alternative ai to the fpis and fnis is calculated according to respective equations (9) or (10): 𝑑𝑑!∗ = / 𝑑𝑑$𝑣𝑣"!", 𝑣𝑣""∗) "&$ (9) (6) the results of the normalized fuzzy decision matrix represented in table 8. k1 k2 k3 k4 k5 weight 0.4 0.167 0.267 0.133 0.033 a1 (0.04,0.19,0.31) (0.02,0.02,0.03) (0.05,0.09,0.27) (0.06,0.08,0.13) (0.00,0.01,0.02) a2 (0.31,0.40,0.40) (0.03,0.06,0.17) (0.03,0.04,0.05) (0.04,0.06,0.08) (0.02,0.03,0.03) step 4. compute the weighted normalized fuzzy decision matrix. a weighted normalized fuzzy decision matrix is calculated by multiplying each of the variables by the wight of the criteria qi given in table 2. the results of the weighted normalized decision matrix are represented in table 9. step 5. compute the fuzzy positive ideal solution (fpis) and fuzzy negative ideal solution (fnis). fpis and fnis are calculated based on equations (7) and (8): 𝐴𝐴∗ = (𝑣𝑣"$∗, 𝑣𝑣",∗, … , 𝑣𝑣"-∗), 𝑤𝑤ℎ𝑒𝑒𝑒𝑒𝑒𝑒 𝑣𝑣"" ∗ = max ! -𝑣𝑣!".. (7) (7) 10 𝐴𝐴+ = (𝑣𝑣"$+, 𝑣𝑣",+, … , 𝑣𝑣"-+), 𝑤𝑤ℎ𝑒𝑒𝑒𝑒𝑒𝑒 𝑣𝑣"" + = min ! -𝑣𝑣!"$. step 6. compute the distance from each alternative to the fpis and the fnis. the distance from each alternative ai to the fpis and fnis is calculated according to respective equations (9) or (10): 𝑑𝑑!∗ = / 𝑑𝑑$𝑣𝑣"!", 𝑣𝑣""∗) "&$ (9) (8) 89 journal of sustainable architecture and civil engineering 2021/1/28 table 10 fpis and fnis values k1 k2 k3 k4 k5 a* (0.04,0.19,0.31) (0.02,0.02,0.03) (0.05,0.09,0.27) (0.06,0.08,0.13) (0.00,0.01,0.02) a(0.31,0.40,0.40) (0.03,0.06,0.17) (0.03,0.04,0.05) (0.04,0.06,0.08) (0.02,0.03,0.03) table 11 distance from fpis and fnis distance from fpis distance from fnis k1 k2 k3 k4 k5 d * k1 k2 k3 k4 k5 da1 0.202 0.080 0.000 0.000 0.017 0.299 0.000 0.000 0.128 0.034 0.000 0.162 a2 0.000 0.000 0.128 0.034 0.000 0.162 0.202 0.080 0.000 0.000 0.017 0.299 the computed fpis and fnis values for each criterion are represented in table 10. discussion concerning the challenges for advanced digital workflow and analysis results step 6. compute the distance from each alternative to the fpis and the fnis. the distance from each alternative ai to the fpis and fnis is calculated according to respective equations (9) or (10): 𝑑𝑑!∗ = / 𝑑𝑑$𝑣𝑣"!", 𝑣𝑣""∗) "&$ (9) 11 𝑑𝑑!+ = / 𝑑𝑑$𝑣𝑣"!", 𝑣𝑣""+) "&$ (10) step 8. rank the alternatives. the alternatives are ranked based on the closeness coefficient from highest being the best alternative, to lowest representing the worst alternative. as in this case, there were only two alternatives, based on the fuzzy topsis results the advanced workflow a2 showed superior results. discussion concerning the challenges for advanced digital workflow and analysis results to move from a typical to advanced method, digital and machine-readable data is of the essence. unfortunately, an advanced digital workflow is currently not a common practice, and several factors are influencing such conditions. firstly, the aec industry is fragmented therefore, there is a lack of data consistency. it is a common practice to build an information model by focusing only on geometry, which is only a part of the semantically enriched bim model. even so, the level of geometrical detail usually is not sufficient enough for the production of reinforcement-based products. it means that highly competitive engineers must detail additionally and adapt particular sets of information for a specific machine and task, which is a time-consuming and error-prone process. furthermore, the involvement of various stakeholders as structural engineers and manufacturers brings into consideration the accountability issues for the final product. another challenge is related to the reliability of data. as a common practice, designers “blindly” use bim libraries, in which usually object attributes are not standardized. therefore, a bunch of mixed and manufacturer/product-specific untrustworthy data gets involved in the projects. depending on the specific product, the use of unstandardized libraries is quite common practice in bim, because it reduces the time for modeling. data exchange possibilities as well play a very important role. aec industry is a huge sector with high fragmentation in information and processes, especially when taking into account the whole building life cycle. that is why even specific tasks (e.g., production of reinforcement-based products) are highly influenced by distributed sources of information prepared by various stakeholders. it shows that data exchange between the industry’s stakeholders is crucial. currently, some of the most common data exchange scenarios intended for reinforcement products are: 1) exchange of geometrical and attribute (10) distance from fpis and fnis is represented in table 11. step 7. compute the closeness coefficient cci for each alternative. the closeness coefficient for each alternative is calculated according to equation (11): 11 𝐶𝐶𝐶𝐶! = /! $ /! $0/! ∗ therefore, the result of closeness coefficient for alternative a1=0.351 and alternative a2=0.649. step 8. rank the alternatives. the alternatives are ranked based on the closeness coefficient from highest being the best alternative, to lowest representing the worst alternative. as in this case, there were only two alternatives, based on the fuzzy topsis results the advanced workflow a2 showed superior results. discussion concerning the challenges for advanced digital workflow and analysis results to move from a typical to advanced method, digital and machine-readable data is of the essence. unfortunately, an advanced digital workflow is currently not a common practice, and several factors are influencing such conditions. firstly, the aec industry is fragmented therefore, there is a lack of data consistency. it is a common practice to build an information model by focusing only on geometry, which is only a part of the semantically enriched bim model. even so, the level of geometrical detail usually is not sufficient enough for the production of reinforcement-based products. it means that highly competitive engineers must detail additionally and adapt particular sets of information for a specific machine and task, which is a time-consuming and error-prone process. furthermore, the involvement of various stakeholders as structural engineers and manufacturers brings into consideration the accountability issues for the final product. another challenge is related to the reliability of data. as a common practice, designers “blindly” use bim libraries, in which usually object attributes are not standardized. therefore, a bunch of mixed and manufacturer/product-specific untrustworthy data gets involved in the projects. depending on the specific product, the use of unstandardized libraries is quite common practice in bim, because it reduces the time for modeling. data exchange possibilities as well play a very important role. aec industry is a huge sector with high fragmentation in information and processes, especially when taking into account the whole building life cycle. that is why even specific tasks (e.g., production of reinforcement-based products) are highly influenced by distributed sources of information prepared by various stakeholders. it shows that data exchange between the industry’s stakeholders is crucial. currently, some of the most common data exchange scenarios intended for reinforcement products are: 1) exchange of geometrical and attribute (11) therefore, the result of closeness coefficient for alternative a1 – 0.351 and alternative a2 – 0.649. step 8. rank the alternatives. the alternatives are ranked based on the closeness coefficient from highest being the best alternative, to lowest representing the worst alternative. as in this case, there were only two alternatives, based on the fuzzy topsis results the advanced workflow a2 showed superior results. to move from a typical to advanced method, digital and machine-readable data is of the essence. unfortunately, an advanced digital workflow is currently not a common practice, and several factors are influencing such conditions. firstly, the aec industry is fragmented therefore, there is a lack of data consistency. it is a common practice to build an information model by focusing only on geometry, which is only a part of the semantically enriched bim model. even so, the level of geometrical detail usually is not sufficient enough for the production of reinforcement-based products. it means that highly competitive engineers must detail additionally and adapt particular sets of information for a specific machine and task, which is a time-consuming and error-prone process. furthermore, the involvement of various journal of sustainable architecture and civil engineering 2021/1/28 90 fig. 4 gartner’s hype curve, 1995. adapted from (linden & fenn, 2003) 13 fig. 4. gartner’s hype curve, 1995. adapted from (linden & fenn, 2003) conclusions even though, the built environment is moving towards digitalization there are still challenges to overcome in order to apply advanced digital workflow and enhance efficiency. on top of the challenges mentioned during the discussion, it is appropriate to notice the training of the whole aec sector supply chain and the need for investments in hardware and software. furthermore, the popularity of bim-based projects in the market, bim demand from the client-side (especially public sector), lack of standards and supportive legislation system, rules, guides, or manuals are the vital components to carry out bim throughout the whole building life cycle as well. in addition, but out of the scope of this research, there are some common challenges related to data consistency and reliability, software and machinery implementation level of bim data standards. according to the results of this study, the following main conclusions were drawn: 1. the digital workflow algorithm proposed in this study showed that a typical workflow does not demand so many investments and training compared to the advanced workflow. however, the potential to increase efficiency, reduce environmental impact and probability of errors, by applying advanced digital workflow methods in the reinforcement processing plant, is promising. 2. the following priority ranking, and significance of the selected rating criteria was obtained using the expert pairwise comparison method: 40.0% performance, efficiency (k1); 26.7% environmental impact (k3); 16.7% investments (k2); 13.3% training (k4); 3.3% quality assurance (k5). the most significant criterion was performance (efficiency). 3. the analysis done using the mcdm fuzzy topsis method for five rating criteria (k1—k5) showed that the advanced production workflow is the most rational alternative for the reinforcement processing plant. the closeness coefficient cca2 for advanced production workflow (alternative a2) is 0.649, which is significantly better in comparison with typical workflow (alternative a1) cca1 = 0 stakeholders as structural engineers and manufacturers brings into consideration the accountability issues for the final product. another challenge is related to the reliability of data. as a common practice, designers “blindly” use bim libraries, in which usually object attributes are not standardized. therefore, a bunch of mixed and manufacturer/product-specific untrustworthy data gets involved in the projects. depending on the specific product, the use of unstandardized libraries is quite common practice in bim, because it reduces the time for modeling. data exchange possibilities as well play a very important role. aec industry is a huge sector with high fragmentation in information and processes, especially when taking into account the whole building life cycle. that is why even specific tasks (e.g., production of reinforcement-based products) are highly influenced by distributed sources of information prepared by various stakeholders. it shows that data exchange between the industry’s stakeholders is crucial. currently, some of the most common data exchange scenarios intended for reinforcement products are: 1) exchange of geometrical and attribute data through open bim standards (.ifc, .bvbs, .xml, etc.); 2) direct use of proprietary (native) data formats and use of intended interfaces of authoring software; 3) extracting data through the api (application programming interface) or bim/cad programming tools (dynamo, generative components, grasshopper, etc.). in the case of exchange through open bim standards, there are some main issues related to: a) too low implementation level into software and especially into machinery equipment. buildingsmart website declares hundreds of software packages compatible with ifc, but the implementation level differs. some are compatible with the ifc4 schema, some are not. significant differences are obvious when we take into consideration particular entities, types, and property sets, which could be extremely relevant for the reinforcement products. the machinery industry does not widely “know” bim standards. that is why ifc implementation level into the reinforcement bending, welding, cutting machines are not sufficient. b) data losses through the exchange process, which is closely subordinated with the implementation level of the ifc schema. those kinds of issues exist due to differences between proprietary and ifc data schemas. direct use of proprietary data standards should be facilitated by the producers of manufacturing equipment. in this case, a specific machine and the data controller must import a proprietary data format suitable for the intended purpose (cutting, welding, bending, etc.). unfortunately, nowadays there is a gap between the equipment manufacturers and bim software vendors. extraction of machinery appropriate data through the bim/cad software api could be the only way to reach demanded data and reduce human intervention as much as possible. however, the api scenario requires information technology specialists with programming skills or highly competitive engineers skilled in object programming tools. nevertheless, the results of this study show great potential for reinforcement manufacturing plants willing to overcome these challenges and adapt the automated workflow. the analysis has revealed that investment evaluation criteria (k3) take second place as a priority for assessed data flow algorithms. as the typical workflow (a1) does not require as many new investments or training (k4) it is found to be superior in 91 journal of sustainable architecture and civil engineering 2021/1/28 conclusions references these two evaluation criteria. however, these factors can be considered short-term in the technology implementation cycle. according to gartner’s hype curve (1995) represented in fig. 4, organizations tend to be easily triggered by new technology and make efforts towards its adaptation (linden & fenn, 2003). though at this time additional investments are necessary for the new technology implementation and training of employees, yet the impact of the new technology is barely visible. hence, at the peak of inflated expectations, many organizations drop the new technology and go back to the old ways, consequently newer reaching the plateau of productivity and losing their primary investments. however, as this research has revealed, the advanced workflow (a2) highly increases the effectiveness (k1) as well as reduces the environmental impact (k2) and the chance of error (k5). therefore, it can be considered as a viable alternative from a long-term perspective. even though, the built environment is moving towards digitalization there are still challenges to overcome in order to apply advanced digital workflow and enhance efficiency. on top of the challenges mentioned during the discussion, it is appropriate to notice the training of the whole aec sector supply chain and the need for investments in hardware and software. furthermore, the popularity of bim-based projects in the market, bim demand from the client-side (especially public sector), lack of standards and supportive legislation system, rules, guides, or manuals are the vital components to carry out bim throughout the whole building life cycle as well. in addition, but out of the scope of this research, there are some common challenges related to data consistency and reliability, software and machinery implementation level of bim data standards. according to the results of this study, the following main conclusions were drawn: 1. the digital workflow algorithm proposed in this study showed that a typical workflow does not demand so many investments and training compared to the advanced workflow. however, the potential to increase efficiency, reduce environmental impact and probability of errors, by applying advanced digital workflow methods in the reinforcement processing plant, is promising. 2. the following priority ranking, and significance of the selected 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sustainable architecture and civil engineering 2021/1/28 about the author darius pupeikis position at the organization head of centre for smart cities and infrastructure at the faculty of civil engineering and architecture main research area bim, digital twins, civil engineering address studentu str. 48-415, lt-51367 kaunas, lithuania tel. +370 689 77371 e-mail: darius.pupeikis@ktu.lt lina morkūnaitė position at the organization msc at department of built environment main research area digital construction, bim, linked building data address thomas manns vej 23, 9220 aalborg ø, denmark e-mail: morkunaite.mail@gmail.com mindaugas daukšys position at the organization prof. at faculty of civil engineering and architecture main research area civil engineering, construction technology address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: mindaugas.dauksys@ktu.lt arūnas aleksandras navickas position at the organization dr. at faculty of civil engineering and architecture main research area digital construction, civil engineering address studentu str. 48, lt-51367 kaunas, lithuania e-mail: arunas.navickas@ktu.lt svajūnas abromas position at the organization constructor-technologist at jsc “serfas” main research area digital construction, civil engineering address technikos str. 7c, lt-51209 kaunas, lithuania e-mail: svaabr@gmail.com this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/ ). 50 darnioji architektūra ir statyba 2013. no. 1(2) journal of sustainable architecture and civil engineering issn 2029–9990 the durability test method for external thermal insulation composite system (etics) used in cold and wet climate countries gintarė griciutė1*, raimondas bliūdžius1 and rosita norvaišienė2 1kaunas university of technology, faculty of civil engineering and architecture, studentų st. 48, lt-51367 kaunas, lithuania 2institute of architecture and construction of kaunas university of technology, tunelio st. 60, lt-44405, kaunas lithuania * corresponding author: gintare.griciute@ktu.lt http://dx.doi.org/10.5755/j01.sace.1.2.2778 the paper proposes the durability prediction method for external thermal insulation composite system (etics), which could be applied in cold and wet climate regions. this improved method is based on the international and nowadays applicable standards for systems service life assessment (etag 004, iso 15462), and completes them with other necessary impact criteria. this study examines the main climate exposures and how these impacts reproduced in the laboratories. the paper analyses the extreme air temperature and rainfall changes, the intensity of ultraviolet radiation (uv) in lithuania. the analysis is based on evaluation of daily and yearly data recorded by meteorological stations. the aim of the research is to compose the accelerated ageing cycle for etics taking into account the characteristics of building materials and identifying the potential degradation factors and indicators. in order to establish the combinations of impacts in ageing cycles, it is necessary the adequate evaluation of intensity of environmental exposures of a certain locality. the basic goal is to create the reliable accelerated ageing cycle which would be as similar as natural ageing. keywords: etics, durability method, service life prediction, cycle, external render. 1. introduction external thermal insulation composite system (etics) is widely used for new construction, reconstruction and renovation of old buildings. the main function of etics is to improve the thermal properties of enclosures and meet the requirements of the national building regulations of thermal performance of buildings. various information about the durability of these systems we can find from the earlier researches (daniotti and paolini 2005, nilica and harmuth 2005, daniotti and paolini 2008, topcu and merkel 2008, stazi et al. 2009). the service life of etics commonly depends on the aging processes of rendering: corrosion, fatigue, loss of colour, staining, soiling, cracking, loss of adhesion, etc. usually renders are exposed to complex atmospheric factors, such as uv radiation, moisture (rain and dew), wind, temperatures changes, which may cause surface cracks, deformations in external thin-layer (tittarelli et al. 2007, ashrae 2007, koči et al. 2012). an external layer of the system, with a typically thickness 1-3mm, must resist the biggest atmospheric effect. thin-layer of render absorbs liquid water into its pores and capillaries. therefore the maximum negative effect occurs in microstructure of render: changes of the internal pore radius of cylindrical pore length bend capillary (bochen et al. 2005, bochen and gil 2009, bochen 2009). it is known, that lower moisture absorption results longer service life (topcu and merkel 2008). accelerated climate ageing investigations are carried out in order to study the durability of various building materials in a substantial shorter time span than natural weather ageing would have allowed. accelerated climate ageing could help to understand degradation processes of etics system. furthermore, accelerated ageing ought to be as similar as natural ageing. several experiments were performed concerning etics service life and different results were obtained due to different test methods (shohet and paciuk 2004, daniotti and paolini 2005, bochen et al. 2005, jelle et al. 2008, daniotti and paolini 2008, bochen 2009, bochen and gil 2009, koči et al. 2012, norvaišienė et al. 2011). the aim of the research is to develop the reliable method of accelerated age ing which could be used to predict the durability of etics under natural ageing conditions. the purpose of this study is to review the previous researches investigating the service life of etics, to examine the main climate exposures and how these may be reproduced and applied in the laboratory conditions. 51 2. methods natural and accelerated ageing tests are extremely important for determination of the ageing characteristics of the materials and prediction of their real durability. many different accelerated ageing tests and evaluation methods have been proposed for predicting and comparing the durability of various kinds of rendering. the essential properties of building products and their durability with respect to climate factors were investigated within a relatively short time compared with natural outdoor climate ageing. researchers tried to find out the correlation between natural and accelerated weathering, but chosen by them climatic impacts of accelerated tests are still different enough (shohet and paciuk 2004, daniotti and paolini 2005, bochen et al. 2005, jelle et al. 2008, daniotti and paolini 2008, bochen 2009, bochen and gil 2009, koči et al 2012). most of these studies were based on the assumption that raised ageing temperatures and water spraying accelerates the reactions responsible for natural ageing. one of the durability investigation methods has been created by finnish researches (nt build 495, 2000). the test method is intended for exposing materials and components used in a building envelope to uv light and table 1. accelerated climatic ageing cycle methods method simulation of climatic impact, oc / duration relative humidity, % observation of deterioration during/after the test equivalence to natural ageinguv rain cold heat nt built 495 +35 ± 5/1h +50 ± 5/1h +75 ± 5/1h spray l/ (m2h) (suggested) 15 ± 2/1h –20 ± 5/1h +23 ± 5/1h 50 ± 10 visual evaluation not estimated j. bochen1 +60/1h spray with gusts/4h –20/4h with uv – open porosity and average pore radius of render 100 cycles equivalent to 1.5–2.7 years j. bochen2 +50/1h spray/0.25h –20/1h with uv – open porosity and average pore radius of render 100 cycles equivalent to 2 years b . d an io tti short-term +35/1h 5 ± 2/1h spray 1 l/(m2h) –20 ± 2/3h +70 ± 2/1h 60 ± 5 microscope analysis water absorption water vapour permeability tensile bond strength of adhesive and base coat to insulator render strip tensile irt, sina, sinb, ti con rhst, degradation survey photos not estimated long-term should be developed e ta g 0 04 heat-rain cycles (80cycle) – +15 ± 5/1h spray 1 l/ (m2 min) – +70 ± 5/3h 30 impact resistance bond strength water vapor permeability visual evaluation the whole service life heat-cold cycles (5 cycles) – – –20 ± 5/16h +50 ± 5/8h 10 freezethaw (30 (cycles) – immersion +23 ± 2/8h –20 ± 2/16h – bond strength visual evaluation heat radiation, water and frost. the results of the test were given as any changes in appearance of the specimens during the test. the description of the cycle is given in table 1. another very similar ageing cycle is proposed by polish scientists j. bochen, s. gil and j. szwabowski (bochen et al. 2005, bochen 2009). the ageing test was carried out in rotational chamber with different impacts of temperatures, relative humidity, uv and rain (table 1). the emphasis has been placed on open capillary porosity, which was examined over time. later on accelerated ageing test has been performed by j. bochen in the same chamber (bochen and gil 2009). the influence of porosity and its structure upon the physical properties of thin-layer external render has been studied after ageing. the results showed that after weathering the changes of porosity, pore structure and chemical microstructure of plaster occurred. this, in turn, have led to thermal and shrinking cracks and weakened the render adhesion to the background. these symptoms were clearly seen on a macro level. the changes of porosity by accelerated ageing and natural weathering were compared (table 1). some researchers seek to find theoretical models capable of predicting rates of rendering natural ageing or 52 their degradation rates (daniotti et al. 2008, daniotti and paolini 2008). b. daniotti suggested experimental program for etics render durability assessment through accelerated laboratory ageing, which is now applied in milan. in order to design the accelerated cycles and assess the proportion between its parts, two ways have been pursued: standard reference (etag 004, 2000, iso 15686-1, 2000, iso 15686-2, 2001) and the analysis of climatic data of milan context (test reference year and uni 10349). author compared results between long-term outdoor exposure and accelerated laboratory ageing cycle. b. daniotti proposed some important conditions regarding etag 004 procedure (daniotti and paolini 2005, daniotti et al. 2008) and stated, that the use of degradation factors and mechanisms should be pointed out in composition of the ageing cycles, in order of ageing phases and maximum intensity of impacts. the test method has been designed in order to compare laboratory ageing and outdoor exposure. the shortages of existing accelerated ageing tests. analyzing overviewed accelerated tests we can state that artificial laboratory tests have advantages and disadvantages. accelerated ageing test, according to nt build 495, in a laboratory always carries the risk that the material might sustain degradation by other mechanisms than those which will take place by natural ageing. the results of the exposure according to this standard should as far as possible be compared with long-term tests performed with the same materials and similar constructions outdoors. the method gives no guidance how the properties of the test specimens should be measured or evaluated after exposure. also, the method does not specify how much the climate exposure and degradation processes are accelerated. analyzing an accelerated cycle created by j. bochen (j. bochen 2009, j. bochen and gil 2009), it was found out that the external layer of rendering was moistened only about 15 minutes during the cycle. is it enough 15 minutes of water spray that render could be completely absorbed by water? also, these two methods (j. bochen and s. gil 2005, j. bochen, 2009) are intended only for external render. etics consists of several layers and it is important to examine the durability of the entire system. the impact of the artificial accelerated cycle should affect not only external layer, but also deeper layers too. by analyzing the durability tests of etics according to etag 004 it is important to pay attention to the few issues: ▪ if the water absorption of system is less than 0.5 kg/m2 after 24 hours, the system will be frost resistant and durable for its whole service life, is this subject true for all kinds of rendering and all climate conditions? ▪ if the defects do not occur after hydrothermal cycling, the system will be weather resistant. is it true? ▪ what kind of decay uv radiation gives to the etics? is it reliable to determine the etics durability by the etag 004 procedure? the accelerated ageing method by b. daniotti includes uv, freeze, heat and rain impacts. after completion of ageing cycles many disruptive and non-disruptive tests are performed for the evaluation of decay (table 1). however, is it necessary to use all these test methods, moreover the earlier studies showed, that the most simple and reliable indicator of render’s ageing is the change of water absorption rate during the ageing. (ashrea 2010, topcu and merkel 2008, norvaišienė et al. 2011, koči et al. 2012) by summarizing all above mentioned accelerated ageing methods, one matter arises: why such climate impacts, durations and amplitudes are chosen for determination of etics durability? most often, accelerated tests applied in durability investigation are based on the complex of extreme conditions imitating the ‘universal environment’ and therefore are inadequate to climatic conditions of a certain locality. when modeling the environmental conditions, it is necessary to find out reasonable testing methods related with the climatic specificity of a certain locality. in order to have more information about the durability of the etics, it is necessary to create the ageing cycles that comply with the terms of use. tests, which incorporate accelerated techniques, can be used when in-use conditions are known, mechanisms of deterioration are understood, key effects causing deterioration have been identified, and the range of effects (application time and severity) can be adequately simulated in a laboratory. 3. experimental in order to find out correlation between the results of short-term and long-term tests, the accelerated and natural weathering has been started. 3.1. material for the modeling of the laboratory accelerated shortterm cycle, the four samples of each etics with dimensions 200×200×50 mm of acrylic, silicate, mineral and silicone renders have been made (fig. 1). method does not specify how much the climate exposure and degradation processes are accelerated. analyzing an accelerated cycle created by j. bochen (j. bochen 2009, j. bochen and gil 2009), it was found out that the external layer of rendering was moistened only about 15 minutes during the cycle. is it enough 15 minutes of water spray that render could be completely absorbed by water? also, these two methods (j. bochen and s. gil 2005, j. bochen, 2009) are intended only for external render. etics consists of several layers and it is important to examine the durability of the entire system. the impact of the artificial accelerated cycle should affect not only external layer, but also deeper layers too. by analyzing the durability tests of etics according to etag 004 it is important to pay attention to the few issues: if the water absorption of system is less than 0.5 kg/m2 after 24 hours, the system will be frost resistant and durable for its whole service life, is this subject true for all kinds of rendering and all climate conditions? if the defects do not occur after hydrothermal cycling, the system will be weather resistant. is it true? what kind of decay uv radiation gives to the etics? is it reliable to determine the etics durability by the etag 004 procedure? the accelerated ageing method by b. daniotti includes uv, freeze, heat and rain impacts. after completion of ageing cycles many disruptive and non-disruptive tests are performed for the evaluation of decay (table 1). however, is it necessary to use all these test methods, moreover the earlier studies showed, that the most simple and reliable indicator of render’s ageing is the change of water absorption rate during the ageing. (ashrea 2010, topcu and merkel 2008, norvaišienė et al. 2011, koči et al. 2012) by summarizing all above mentioned accelerated ageing methods, one matter arises: why such climate impacts, durations and amplitudes are chosen for determination of etics durability? most often, accelerated tests applied in durability investigation are based on the complex of extreme conditions imitating the ‘universal environment’ and therefore are inadequate to climatic conditions of a certain locality. when modeling the environmental conditions, it is necessary to find out reasonable testing methods related with the climatic specificity of a certain locality. in order to have more information about the durability of the etics, it is necessary to create the ageing cycles that comply with the terms of use. tests, which incorporate accelerated techniques, can be used when in-use conditions are known, mechanisms of deterioration are understood, key effects causing deterioration have been identified, and the range of effects (application time and severity) can be adequately simulated in a laboratory. 3. experimental in order to find out correlation between the results of short-term and long-term tests, the accelerated and natural weathering has been started. 3.1. material for the modeling of the laboratory accelerated shortterm cycle, the four samples of each etics with dimensions 200×200×50 mm of acrylic, silicate, mineral and silicone renders have been made (fig. 1). fig. 1. specimens prepared of etics for artificial accelerated exposure (200×200×50 mm) for the natural ageing sample panels 1000×500×50 mm four samples of each type of rendering were exposed on a 56 o slope wooden south facing rack, placed on the flat roof of building (fig.2). during natural ageing relative humidity, uv radiation, wind velocity, temperatures changes and moisture (rain and dew) impacts were recorded by sensors at the meteorological station of institute of architecture and construction. fig. 2. the natural exposure of etics panels (1000×500×50 mm) on the wooden test rack the water absorption, bond strength and macrostructure analysis after 6, 12, 18, 24 months of natural weathering will be measured to estimate the degradation of renders. four samples of each types of rendering coats on plastic strip were made, in order to measure the rate of water absorption of external layer (fig. 3). fig. 3. the samples of external render coats on plastic strips: 1 – acrylic render, 2 – silicate render, 3 – mineral render, 4 – silicon render fig. 1. specimens prepared of etics for artificial accelerated exposure (200×200×50 mm) for the natural ageing sample panels 1000 × 500 × 50 mm four samples of each type of rendering were exposed on a 56o slope wooden south facing rack, placed on the flat roof of building (fig. 2). during natural ageing relative humidity, uv radiation, wind velocity, temperatures 53 changes and moisture (rain and dew) impacts were recorded by sensors at the meteorological station of institute of architecture and construction. method does not specify how much the climate exposure and degradation processes are accelerated. analyzing an accelerated cycle created by j. bochen (j. bochen 2009, j. bochen and gil 2009), it was found out that the external layer of rendering was moistened only about 15 minutes during the cycle. is it enough 15 minutes of water spray that render could be completely absorbed by water? also, these two methods (j. bochen and s. gil 2005, j. bochen, 2009) are intended only for external render. etics consists of several layers and it is important to examine the durability of the entire system. the impact of the artificial accelerated cycle should affect not only external layer, but also deeper layers too. by analyzing the durability tests of etics according to etag 004 it is important to pay attention to the few issues: if the water absorption of system is less than 0.5 kg/m2 after 24 hours, the system will be frost resistant and durable for its whole service life, is this subject true for all kinds of rendering and all climate conditions? if the defects do not occur after hydrothermal cycling, the system will be weather resistant. is it true? what kind of decay uv radiation gives to the etics? is it reliable to determine the etics durability by the etag 004 procedure? the accelerated ageing method by b. daniotti includes uv, freeze, heat and rain impacts. after completion of ageing cycles many disruptive and non-disruptive tests are performed for the evaluation of decay (table 1). however, is it necessary to use all these test methods, moreover the earlier studies showed, that the most simple and reliable indicator of render’s ageing is the change of water absorption rate during the ageing. (ashrea 2010, topcu and merkel 2008, norvaišienė et al. 2011, koči et al. 2012) by summarizing all above mentioned accelerated ageing methods, one matter arises: why such climate impacts, durations and amplitudes are chosen for determination of etics durability? most often, accelerated tests applied in durability investigation are based on the complex of extreme conditions imitating the ‘universal environment’ and therefore are inadequate to climatic conditions of a certain locality. when modeling the environmental conditions, it is necessary to find out reasonable testing methods related with the climatic specificity of a certain locality. in order to have more information about the durability of the etics, it is necessary to create the ageing cycles that comply with the terms of use. tests, which incorporate accelerated techniques, can be used when in-use conditions are known, mechanisms of deterioration are understood, key effects causing deterioration have been identified, and the range of effects (application time and severity) can be adequately simulated in a laboratory. 3. experimental in order to find out correlation between the results of short-term and long-term tests, the accelerated and natural weathering has been started. 3.1. material for the modeling of the laboratory accelerated shortterm cycle, the four samples of each etics with dimensions 200×200×50 mm of acrylic, silicate, mineral and silicone renders have been made (fig. 1). fig. 1. specimens prepared of etics for artificial accelerated exposure (200×200×50 mm) for the natural ageing sample panels 1000×500×50 mm four samples of each type of rendering were exposed on a 56 o slope wooden south facing rack, placed on the flat roof of building (fig.2). during natural ageing relative humidity, uv radiation, wind velocity, temperatures changes and moisture (rain and dew) impacts were recorded by sensors at the meteorological station of institute of architecture and construction. fig. 2. the natural exposure of etics panels (1000×500×50 mm) on the wooden test rack the water absorption, bond strength and macrostructure analysis after 6, 12, 18, 24 months of natural weathering will be measured to estimate the degradation of renders. four samples of each types of rendering coats on plastic strip were made, in order to measure the rate of water absorption of external layer (fig. 3). fig. 3. the samples of external render coats on plastic strips: 1 – acrylic render, 2 – silicate render, 3 – mineral render, 4 – silicon render fig. 2. the natural exposure of etics panels (1000×500×50 mm) on the wooden test rack the water absorption, bond strength and macrostructure analysis after 6, 12, 18, 24 months of natural weathering will be measured to estimate the degradation of renders. four samples of each types of rendering coats on plastic strip were made, in order to measure the rate of water absorption of external layer (fig. 3). method does not specify how much the climate exposure and degradation processes are accelerated. analyzing an accelerated cycle created by j. bochen (j. bochen 2009, j. bochen and gil 2009), it was found out that the external layer of rendering was moistened only about 15 minutes during the cycle. is it enough 15 minutes of water spray that render could be completely absorbed by water? also, these two methods (j. bochen and s. gil 2005, j. bochen, 2009) are intended only for external render. etics consists of several layers and it is important to examine the durability of the entire system. the impact of the artificial accelerated cycle should affect not only external layer, but also deeper layers too. by analyzing the durability tests of etics according to etag 004 it is important to pay attention to the few issues: if the water absorption of system is less than 0.5 kg/m2 after 24 hours, the system will be frost resistant and durable for its whole service life, is this subject true for all kinds of rendering and all climate conditions? if the defects do not occur after hydrothermal cycling, the system will be weather resistant. is it true? what kind of decay uv radiation gives to the etics? is it reliable to determine the etics durability by the etag 004 procedure? the accelerated ageing method by b. daniotti includes uv, freeze, heat and rain impacts. after completion of ageing cycles many disruptive and non-disruptive tests are performed for the evaluation of decay (table 1). however, is it necessary to use all these test methods, moreover the earlier studies showed, that the most simple and reliable indicator of render’s ageing is the change of water absorption rate during the ageing. (ashrea 2010, topcu and merkel 2008, norvaišienė et al. 2011, koči et al. 2012) by summarizing all above mentioned accelerated ageing methods, one matter arises: why such climate impacts, durations and amplitudes are chosen for determination of etics durability? most often, accelerated tests applied in durability investigation are based on the complex of extreme conditions imitating the ‘universal environment’ and therefore are inadequate to climatic conditions of a certain locality. when modeling the environmental conditions, it is necessary to find out reasonable testing methods related with the climatic specificity of a certain locality. in order to have more information about the durability of the etics, it is necessary to create the ageing cycles that comply with the terms of use. tests, which incorporate accelerated techniques, can be used when in-use conditions are known, mechanisms of deterioration are understood, key effects causing deterioration have been identified, and the range of effects (application time and severity) can be adequately simulated in a laboratory. 3. experimental in order to find out correlation between the results of short-term and long-term tests, the accelerated and natural weathering has been started. 3.1. material for the modeling of the laboratory accelerated shortterm cycle, the four samples of each etics with dimensions 200×200×50 mm of acrylic, silicate, mineral and silicone renders have been made (fig. 1). fig. 1. specimens prepared of etics for artificial accelerated exposure (200×200×50 mm) for the natural ageing sample panels 1000×500×50 mm four samples of each type of rendering were exposed on a 56 o slope wooden south facing rack, placed on the flat roof of building (fig.2). during natural ageing relative humidity, uv radiation, wind velocity, temperatures changes and moisture (rain and dew) impacts were recorded by sensors at the meteorological station of institute of architecture and construction. fig. 2. the natural exposure of etics panels (1000×500×50 mm) on the wooden test rack the water absorption, bond strength and macrostructure analysis after 6, 12, 18, 24 months of natural weathering will be measured to estimate the degradation of renders. four samples of each types of rendering coats on plastic strip were made, in order to measure the rate of water fig. 3. the samples of external render coats on plastic strips: 1 – acrylic render, 2 – silicate render, 3 – mineral render, 4 – silicon render fig. 3. the samples of external render coats on plastic strips: 1 – acrylic render, 2 – silicate render, 3 – mineral render, 4 – silicon render it was examined the water absorption of external render layer of etics in order to determine what is the required duration of water impact that render could be completely saturated by water. 3.2. modeling of climate impacts in order to predict service life of etics, the accelerated climatic cycle was composed on the basis of earlier scientific research (shohet and paciuk 2004,topcu and merkel 2008, norvaišienė et al. 2010, jelle et al. 2008) and the statistic data of the lithuanian climate (rsn 156-94, 1995), with respect to the average rain duration, uv radiation and the extreme outdoor temperatures in summer and winter modeling of rain impact. for modeling the rain impact cycle it the water absorption rate was determined (lst en iso 15148, 2004). fig. 4 demonstrates the increment of water absorption intensity during water absorption test for etics samples. 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0 10 20 30 40 50 w a t e r a b s o r p t i o n w a f t e r 4 8 h , k g / m 2 time, h 1 4 3 2 24 fig. 4. water absorption rates of etics samples from water surface: 1 – with acrylic render, 2 – with silicate render, 3 – with mineral render, 4 – with silicone render water absorption curves show, that after immersion of etics samples into the water, the intensity of water absorption slowdown after about 24 h. the same water absorption test was performed with external render coats on plastic strip. the water absorption was measured every 5 minutes (fig. 5). the water absorption slowdown after 4h and later on it continues to absorb water very slowly. fig. 5. water absorption rates of external render samples on plastic strip from water surface: 1 – with acrylic render, 2 – with silicate render, 3 – with mineral render, 4 – with silicon render these tests show that water absorption of whole etic system is more intensive and has higher values of water absorption than water absorption of external render of etics on plastic. for accelerated ageing it is important to analyze the physical changes of whole etic system, although the maximal negative effects of water occurs in external layer of render. from these tests it follows that the duration of rain impact we should chose not less than 4h in order to saturate by water the whole render of etics. on the basis of the climatic data (rsn 156-94, 1995), the average rain duration on the vertical south-west surface in lithuania is about 7h and it repeats about 16 times per 54 year. in order to imitate the rain impact on etics samples the duration of water impact for 7h have been chosen. modeling of cold impact. it has been found out that the cold waves of –1.5 °c degrees temperature in lithuania are repeated approximately 24.16 times, –4.5 °c degrees – 7.44 times, –8 °c degrees – 4.44 and –12 °c degrees – 5.72 times per year (rsn 156-94, 1995). on the basis of earlier scientific research it was estimated correlation between wave period and its amplitude: the period is growing by increasing the amplitude (ramanauskas and stankevičius 1998). following that the cooling waves of –1,5 °c (24.16 times) have very low impact, the optimal variant was chosen: the impact of the annual natural frost cycles on the etics should be imitated by 18 freezing cycles per year each lasting for not less than 7 hours at the ambient air temperature of –12 °c. modeling of heat and uv radiation impacts. the +40 °c heating phase temperature has been chosen as an effective surface temperature due to direct sun irradiation on the surface during mean nebulosity (rsn 156-94, 1995). in order to determine the necessary duration of drying during ageing cycle the drying test of samples has been performed. fig. 6 demonstrates the drying intensity rate during drying test for etics samples. the samples dry out to the original weight within 24 h (at +40 °c). therefore, the duration of heating phase has been adjusted to the need of sufficient drying out of samples during accelerated ageing of samples in the climatic chamber. m o i s t u r e l o s s d u r i n g 2 4 h w a t e r a b s o r p t i o n w a f t e r 4 8 h , k g / m 2 g o f d r y i n g , k g / m 2 0, 0, 0, 0, 0, 0, 0, 0, -1,2 -1 -0,8 -0,6 -0,4 -0,2 0 0 ,1 ,2 ,3 ,4 ,5 ,6 ,7 ,8 0 0 0 10 5 0 timme, 1 20 h 10 t 2 tim 24 me, h 3 1 h 30 5 1 2 4 3 4 20 1 2 4 3 0 0 50 1 4 3 2 25 2 3 4 1 0 4 4 1 fig. 6. drying rates curves of etics samples: 1 – with acrylic render, 2 – with silicate render, 3 – with mineral render, 4 – with silicon render at the same time the uv radiation impact was included. uv makes only 6 %, of the whole solar radiation in lithuania; however, in the spectrum of all solar radiation waves, its impact on the finish material ageing is the most extensive (norvaišienė et al. 2010). the intensity of uv in laboratory accelerated cycle has been calculated on the basis of the highest hourly intensity of solar radiation onto a vertical south surface. in the 290–450 mm uv wave range, under the conditions of the climatic chamber the intensity should be 35–40 w/m2. the calculated uv radiation period embraces 448 h/year. the laboratory accelerated ageing cycle for etics samples is given below (table 2). after 16 cycles (28 days) of spraying, freezing, uv radiation and heating, the water absorption and bond strength will be respectively measured in order to determine the accelerated ageing effect to etics. 16 ageing cycles should be adequate to one natural year. 4. discussion in most the cases the accelerated aging cycles underestimate specifics of country’s geographical location and prevailing climate, therefore these cycles cannot be applied in every climate zone. the intensities of weathering impacts and duration of the accelerated cycles are also not fully assessed. our accelerated aging cycle was based on previous results (norvaišienė et al. 2010) and lithuanian climatological data. the most important climatic factors were selected which were involved into accelerated ageing cycle. during laboratory ageing process the most important weathering impacts and their sets, which determine the ageing and decay of etics are to be modelled. having compared the water absorption of etics samples and samples on plaster strips it has been observed that both cases demonstrated different results. it was experimentally proved, that water absorption rate of external layer on plastic strips increases considerably only during the first 2 h of moistening and after 4 h it fully saturates. so it is obvious that it is not enough 15 minutes to saturate the external layer of etics by water, as proposed in j. bochen’s method. the analysis of water absorption of etic systems has shown that the silicate rendering absorbs the most of all the renderings (0.62 kg/m2 per 24 h), and acrylic rendering – table 2. the accelerated ageing with uv-heating-moistening-freezing impacts description air temperature, °c process total exposure period, h observation of deterioration during/after the test equivalence to natural ageing rain +20 spraying 112 macroscopic analysis water absorption visual evaluation bond strength 28 days ≈ 1 year cold –12 freezing 112 uv radiation 35-40w/m2 and heat +40 uv lamps and heating 448 the phases of one ageing cycle: rain +20 spraying 7 note: repetitions for one natural year weathering imitation – 16 timescold –12 freezing 7 uv and heat +40 drying 28 55 the less of all (0.33 kg/m2 per 24 h). however according to water absorption rates of external layer of rendering the maximal rate of water absorption comes to mineral (0.33 kg/m2 per 24 h) and minimal rate – to acrylic layer (0.17 kg/m2 per 24 h). this means that the initial water absorption rate depends not only on kind of external layer, but of etics deeper layers too, i.e. reinforcement layer. the offered accelerated weathering cycle could be useful for etics manufacturers and it could be used for testing and proof of highly frost-resistant products. the accelerated climatic testing continues and the results will be presented later. correlation between the results obtained from artificial accelerated ageing and the natural weathering will be established. 5. conclusions during the creation of the accelerated ageing cycle the lithuanian climate characteristics and results of earlier research have been taken into account. this accelerated cycle also could be applied for imitation of weathering impacts of rainy localities in middle climate zones. in the climatic chamber the impact of uv radiation has been imitated for 28 hours with intensity of 35–40 w/ m2 and impact of summer heating – by conditioning at +40 °c temperatures. the impact of rain has been imitated by spraying for 7 hours with intensity of 1 l/ (m2∙min). the impact of winter cold has been imitated by 7 hours freezing at –12 °c temperatures. all 16 cycles takes 28 days (about 672 hours). as mentioned above, the created ageing cycle includes the main environmental impacts, however the durations and intensities of cycles are different. our modeled cycle is calculated for certain area, i.e. for lithuanian climate. for determination of durability of etics four evaluation indicators have been chosen: macroscopic analysis, water absorption rate, mechanical adhesive strength and visual monitoring, because these are the sufficient indicators for durability evaluation of systems. these evaluation indicators are considerably simpler than evaluation techniques offered by b. daniotti. the whole accelerated ageing cycle lasts for 28 days which corresponds to about one natural year in the most unfavorable conditions. references bochen j., gil s., szwabowski j. 2005. influence of ageing process on porosity changes of the external plasters. cement and concrete composites, 27, 769–775. http://dx.doi.org/10.1016/j.cemconcomp.2005.01.003 bochen j. 2009. properties of pore structure of thin-layer external plasters under ageing in simulated environment. construction and building materials, 23, 2958-2963. http://dx.doi.org/10.1016/j.conbuildmat.2009.02.041 bochen j., gil s. 2009. study on the microstructure of thin-layer facade plasters of thermal insulating system during artificial weathering. construction and building materials 23, 2559– 2566. http://dx.doi.org/10.1016/j.conbuildmat.2009.02.028 daniotti b., paolini r. 2005. durability design of external thermal insulation composite system with rendering. in: procceedings of the 10dbmc international conference on durability of building materials and components lyon france, 17-20 april 2005 daniotti b., paolini r. 2008. experimental programme to assess etics cladding durability. in: procceedings of the 11dbmc international conference on durability of building materials and components istanbul turkey, 11-14 may 2008 daniotti b., spagnolo s. l., paolini r. 2008. climatic data analysis to define accelerated ageing for reference service life evaluation. in: proceedings of the 11dbmc international conference on durability of building materials and components istanbul, turkey 11-14 may 2008. etag 004.2000. guideline for european technical approval of external thermal insulation composite systems with rendering, european organisation for technical approval. brussels, 2000. 114 p. iso 15686-1. buildings and constructed assets-service life planning. part 1: general principles, 2000. 41 p. iso 15686-2. buildings and constructed assets-service life planning. part 2: service life prediction procedures, 2001. 24 p. jelle b. p., nilsen t., hovde p. j., gustavsen a. 2008. accelerated climate ageing of building materials and application. of the attenuated total reflectance (atr) fourier transform infrared (ftir) radiation experimental method. in: proceedings of the 8th symposium on building physics in the nordic countries, vol. 2. (dtu byg report r-189). koči v., madera j., robert č. r. 2012. exterior thermal insulation systems for aac building envelopes: computational analysis aimed at increasing service life. energy and buildings, 47, 84–90. http://dx.doi.org/10.1016/j.enbuild.2011.11.030 künzel m. 2010. factors determining surface moisture on external walls. in: proceedings of the xi international conference thermal performance of the exterior envelopes of whole buildings 2010. 1–6. lst en iso 15148:2004 hygrothermal performance of building materials and products determination of water absorption coefficient by partial immersion (iso 15148:2002). nilica r., harmuth h. 2005. mechanical and fracture mechanical characterization of building materials used for external thermal insulation composite systems. cement and concrete research, 35, 1641–1645. http://dx.doi.org/10.1016/j.cemconres.2005.04.001 norvaišienė r., burlingis a., stankevičius v. 2010. durability tests on painted facade rendering by accelerated ageing materials science. vol. 16, no. 1, 80–85. norvaišienė r., griciutė g., bliūdžius r., ramanauskas j. 2011. the changes of moisture absorption properties during the service life of external thermal insulation composite system. in: proceedings of the. 20th international baltic conference materials engineering 2011, kaunas lithuania, 13 p. ar viso 98 p. nt build 495. 2000. nordtest method. building materials and components in the vertical position: exposure to accelerated climatic strains. finland, 2000. 4 p. ramanauskas j., stankevičius v. 1998. wather durability of external wall thermal insulation system with a thin-layer plaster finish. civil engineering, vol iv, no 6, 206–213. rsn 156-94. 1995. building climatology. ministry of building and urban development of the republic of lithuania. vilnius, 1995. 136 p. shohet i. m., paciuk m. 2004. service life prediction of exterior cladding components under standard conditions. construction management and economics 22, 1081–1090. http://dx.doi.org/10.1080/0144619042000213274 56 stazi f., perna c. d., munafo p. 2009. durability of 20-year-old external insulation and assessment of various types of retrofitting to meet new energy regulations. energy and buildings, 41, 721–731. http://dx.doi.org/10.1016/j.enbuild.2009.02.008 tittarelli f., moriconi g., bonazza a. 2008. atmospheric deterioration of cement plaster in a building exposed to a urban environment. journal of cultural heritage. 9, 203–206. http://dx.doi.org/10.1016/j.culher.2007.09.005 topcu d., merkel h. 2008. durability of external wall insulation systems with extruded polystyrene insulation boards. in: proceedings of the 11th international conference on durability of building materials and components, istanbul turkey, 2008. received 2012 11 12 accepted after revision 2013 02 23 gintarė griciutė – phd. student at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. main research area: the external thermal insulation composite systems life cycle prediction. address: kaunas university of technology, faculty of civil engineering and architecture, studentų st. 48, lt-51367 kaunas, lithuania. tel.: +370 37 350799 e-mail: gintare.griciute@ktu.lt raimondas bliūdžius – professor at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. main research area: thermal processes in buildings, thermal and hydro properties of building materials and elements. address: kaunas university of technology, faculty of civil engineering and architecture, studentų st. 48, lt-51367 kaunas, lithuania. tel.: +370 37 350799 e-mail: raimondas.bliudzius@ktu.lt rosita norvaišienė – chief engineer-researcher at kaunas university of technology, institute of architecture and construction, science laboratory of building thermal physics. main research area: sustainable building materials; durability testing of building materials; damage due to moisture penetration. address: kaunas university of technology, institute of architecture and construction, tunelio st., 60, lt-51367 kaunas, lithuania. tel.: +370 37 350799 e-mail: rosita.norvaisiene@ktu.lt journal of sustainable architecture and civil engineering 2023/1/32 162 adaptive workplace with indoor health and comfort approach toward sustainable city received 2022/10/15 accepted after revision 2023/03/17 adaptive workplace with indoor health and comfort approach toward sustainable city jsace 1/32 hilma tamiami fachrudin department of architecture, faculty of engineering, universitas sumatera utara, indonesia *corresponding author: hilma@usu.ac.id https://doi.org/10.5755/j01.sace.32.1.32519 journal of sustainable architecture and civil engineering vol. 1 / no. 32 / 2023 pp. 162-171 doi 10.5755/j01.sace.32.1.32519 abstract introduction the covid-19 pandemic has an impact on public health, including workplace occupant. the spread of the coronavirus occurs a lot in the workplace. indoor health and comfort play an important role in providing a healthy and comfortable workplace. work patterns during the covid-19 pandemic have changed with the work from home and physical distancing policies. the arrangement of the workplace interior accompanied by indoor health comfort can affect the work experience of occupant. this study aims to produce an adaptive workplace layout design with an indoor health and comfort approach based on occupant perception toward sustainable city. this study uses mix methods with observation and questionnaire survey techniques. the object of research is ten offices in the medan city, indonesia. observations were made to analyze the layout of the workplace, then questionnaires were distributed to employees to analyze their perceptions of comfort and the application of health protection in the workplace. the variables are lighting, ventilation, temperature and humidity, distance of workbench, and health protection. the results showed that the workplace must provide good air quality with the exchange of air through ventilation. workbench spacing and the use of barriers are most recommended. a workplace with cubical layouts can be arranged parallel to the desk divider as a screen between desks. whereas in a workplace with non-cubical layouts, work desks can use zig-zag or non-parallel seating arrangements and dividers between tables. office buildings should prepare a workplace that concerned with space efficiency and comfortable indoor space. keywords: adaptive, indoor health and comfort, sustainable city, workplace design. adaptive architecture is the capacity of buildings and humans to adapt that supports dynamic interactions between buildings and their users. the adaptive architecture design strategy has 6 strategies, namely available, flexible, refutable, scalable, movable, and reusable (schimdt, 2009). adaptive architecture ideally responds to the needs of sustainable architecture because it arises from the use of various spatial components. each time the space is moved, it creates new spatial interaction between the interior and the exterior. adaptive architecture answers the need for spatial savings which refers to the use of built forms, resulting in environmental diversity, including the complexity and variability of exterior components (demers et al., 2014). adaptive architecture focuses on buildings or their components that are specifically designed to be able to adapt both to the surrounding environment, its occupants, and the objects in it (schnädelbach, 2010). this adaptation mechanism can be done automatically or with human intervention. an exploratory space also has space flexibility which is realized by the use of built-in furniture that can be arranged according to the type of item. in designing an adaptive and exploratory space, 163 journal of sustainable architecture and civil engineering 2023/1/32 designers need to pay attention to the influence of lighting, space area, flexibility, furniture, and spatial quality on the performance they want to present in a space (sharfina and purwanita, 2015). adaptability allows to enhance the user’s wellbeing and safety by achieving comfort, health, security, indoor environmental quality, life quality as well as a good interactivity with the building and other users (naqib, 2009). several studies have linked the concept of indoor health and comfort with the concept of adaptive space (naqib, 2009) and green workplaces (wardhani et al., 2020). workplace before the pandemic, using an open concept to support the flexibility of residents. the co-working space concept supports performance efficiency and is more flexible (nediari et al., 2021). corridors in the workplace should avoid two-way traffic. corridors for two people to walk should have a minimum width of 1.2 1.5 meters. some activities can be done in one room only. during the covid-19 pandemic, work patterns changed and some employees worked from home (kaushik and guleria, 2020). the quality of the indoor environment is related to occupants satisfaction in the workplace. besides affecting health, it also affects employees productivity (esfandiari, et al., 2017). workplace depends on the condition of the building and its urban context. workplace interior arrangement considering the main building with better attributes and performance levels in terms of location, design, construction and management, which makes retrofitting workplace interiors more effective and environmental impact and improvement of employee work experience (gou, 2016). energy efficiency is one of the indicators for realizing sustainable city. there are several benefits of energy efficiency, one of which is to create a healthy indoor living environment with healthy air temperatures, humidity levels, noise levels and improved quality (sodiq et al., 2019). the indoor environment quality can affect the health, comfort and productivity of employees. the use of materials with low emissions can reduce indoor pollutants (gou, 2016). one of the challenges during the post-civod-19 pandemic is to provide a comfortable and safe workplace from coronavirus transmission. workplace design adaptation is needed as a facility for employees. in addition, indoor health and comfort which is part of the green building principle are considered in providing a healthy workplace. this study aims to produce an adaptive workplace layout design with an indoor health and comfort approach based on occupant perception toward sustainable city. workplace workplace in the office is divided into private space as much as 70-80% and shared space as much as 20-30%. in facilitating activities in the workplace, space efficiency is needed that adapts to technology that leads to transformation (nediari et al., 2021). in the workplace, a good quality indoor environment can increase worker productivity (vgbc, 2019). office buildings are occupied by many tenants so efforts are needed to make workplaces with green interiors which are the result of green buildings (gou, 2016). according to nediari et al. (2021), the arrangement of office interiors after the pandemic must pay attention to distance, furniture layout, and air conditioning systems. a safe workplace arrangement has an individual distance in the workplace of 2 meters or 6 feet and the furniture layout is back to back. the size of the office desk has been reduced from 1.8 m to 1.4 m. use of panels between employees is required. the covid-19 pandemic has resulted in changes in work patterns and the provision of workplaces. working from home is one way to reduce the number of employees working in one workplace at the same time. things that need to be considered in the wfh (working from home) concept and working in an office during a pandemic include human connectivity, maintaining normality, social distancing, infrastructure, collaboration, security, policy frameworks, and emotional well-being (kaushik and guleria, 2020). journal of sustainable architecture and civil engineering 2023/1/32 164 indoor health and comfort is one of the principles in green building (gbci, 2018). efforts to apply the green concept to buildings must be supported by green behavior by users (fachrudin, h. t. et al., 2021). some recommendations for workplace design to obtain a usable indoor environmental quality according to ashrae (2020) consist of dilute, exhaust, control, and cleaning. dilute requires increased ventilation to enter outside air, for example by disabling demand-control ventilation (dcf), increasing the setpoint of the outside air damper or minimum airflow, operating the air handling unit with 100 percent outside air if possible, maintaining the system ventilation operates for a long time and applies a sequence of air cleaning before and after occupancy. exhaust is concerned with keeping the exhaust air in the restroom operating continuously. there are several recommendations for humidity control in the room, namely installing a humidity sensor to maintain a relative humidity of 40-60%, deactivating resetting the air release temperature during humid weather, and ensuring the hot water heating system is activated to control humidity. air purification recommends upgrading the filter to merv-13, adding a portable room air purifier with a hepa or high-merv filter, installing ultraviolet lamps in workplace or air-handling equipment, and retrofitting the air-handling equipment with a suitable air-purifying device. recommendations for maintaining indoor quality in the workplace during a pandemic (guo et al., 2021) are: ventilation with adequate outside air and effective airflow patterns are the most important strategies to reduce the risk of sars-cov-2 transmission; supply as much outdoor air as possible; hvac related devices open 2 hours before and after occupancy; using a portable room air purifier; maintain filters regularly; on ac devices (eg. ahu) should disable sector recirculation; it is also recommended to maintain negative pressure in the toilet and regularly check the water seal; control the temperature between 17 and 28◦c and control the relative humidity between 40% and 70%; maintain physical distance; hand hygiene; respiratory etiquette; and proper use of face masks. contribution to the comfort and well-being of building occupants can be made by setting minimum standards for indoor air quality (iaq), consisting of mechanically ventilated rooms and naturally ventilated rooms (usgbc, 2019). minimum indoor air quality performance contributes to occupant comfort and well-being (gbi index, 2011). workplace should provide sufficient fresh air supply for at least 90% of the clean area of the occupied building and conduct indoor air quality testing (vgbc, 2019). air quality can affect occupants and improve their well-being. building sick syndrome is characterized by cases of respiratory disease in building occupants. this should be addressed with a good indoor environmental quality. maintaining workplace air quality is done by optimizing air circulation and sunlight entering the workplace; air conditioning filter cleaning; conducting engineering to prevent transmission such as installing barriers or glass screens for workers serving customers, arranging seating to be one meter apart at the desk/work area, during meetings, in the canteen, during breaks, and others (kemenkes ri, 2020). indoor health and comfort can be achieved by providing adequate ventilation of the room with outside air and introducing a network of indoor air quality sensors (rehva, 2020). air quality in the workplace must be improved and is a concern for architects and interior designers because it affects the health and productivity of occupants (esfandiari et al., 2017). a good interior layout arrangements and ventilation systems are needed in the workplace. indoor health and comfort can be measured from the introduction of outdoor air, co2 monitoring, environmental tobacco smoke control, chemical pollutants, exterior views, visual comfort, thermal comfort, and acoustic comfort (gbci, 2016) and (gbci, 2018). use of natural or mechanical ventilation; upgrading filters where appropriate and monitoring hvac can provide indoor health and comfort (ecdc, 2020). indoor health and comfort 165 journal of sustainable architecture and civil engineering 2023/1/32 this research uses qualitative and quantitative methods. the data collection technique was by conducting observations in ten office building in medan city, indonesia. the workplaces that are the object of research are five workplaces using cubical concept layout, and five non-cubical workplaces. observations were made to analyze the layout of the workplace and its suitability for indoor health and comfort. observations were made on the location of windows and ventilation as a source of natural lighting and airing, artificial lighting used, ventilation systems used including the direction of the wind from the air conditioner in the room, the layout of the furniture and health protection applied to the workplace. then, survey with questionnaire was conducted to occupants of the office buildings to get employee’ perceptions of the indoor and health comfort in the workplace. there are 123 occupants became respondents in this research. the variables of the indoor health and comfort are lighting, ventilation, thermal and humidity, work furniture distance and health protection in the workplace. questionnaire forms were given to employees using a likert scale of 1-5. lighting consists of the use of natural lighting in the workplace, the presence of open glass on each side of the room, the comfort of indoor light, natural lighting, and artificial lighting. ventilation consists of the availability of ventilation, the availability of clean air in the room, and efforts to enter clean air into the room. thermal and humidity consist of the temperature in the room and the use of air conditioning. distance regarding workplace layouts focuses on the distance between work desks, limiting work desks and limiting the number of people in closed spaces. health protection consists of implementing work from home and providing equipment for health protection. the analysis used is descriptive analysis. the analysis results are input in preparing an adaptive workplace design layout in the post-pandemic covid 19 with an indoor health and comfort approach. methods results and discussion lighting lighting is an important part of the workplace. some rooms use natural lighting and some rely on artificial lighting. some workplaces have good lighting, but there is workplace that place work desks away from light sources. so they added a lamp on the desk. lighting helps occupants in carrying out their activities. workplace with glass windows can take advantage of sunlight for natural lighting into the room (fachrudin et al., 2022). fig. 1 natural lighting in workplace ventilation efforts to clean the air by entering fresh air from outside are following the recommendations of gbci (2018). it is important to clean indoor air to get good air quality (rehva, 2020). mechanical ventilation and natural ventilation can be used to maintain indoor air quality (usgbc, 2019). ventilation in the workplace is used to enter sunlight and fresh air from outside. in a workplace with a cubical layout, the building envelope uses glass but is not used to enter sunlight and fresh air from outside. meanwhile, in workplaces with non-cubical layouts, ventilation is used to enter fresh air from outside by opening the windows twice a day. opening windows during peak hours are recommended by ashrae (2020) and rehva (2020) and optimizing sunlight is recommended by kemenkes ri (2020). journal of sustainable architecture and civil engineering 2023/1/32 166 fig. 2 ventilation in workplace thermal dan humidity in a closed workplace with a centralized air system, it is better to use a co2 detector and air filter so that indoor air quality is maintained (ashrae, 2020; rehva, 2020; ecdc, 2020 and kemenkes ri, 2020). based on observation, ac used in all workplaces is set at a temperature of 22fig. 3 temperature control in workplace with split ac system 25◦c. in a workplace that uses a centralized air conditioning system, employees cannot control the temperature in the room. whereas in a workplace with split ac, employees can can determine the temperature of the ac themselves.temperature and humidity settings in all workplaces have complied with ashrae (2020) regulations. distance workplaces with cubical layouts have a workbench distance of 1 until 1.2 m and a divider between tables. setting the distance of the workbench is adjusted to the needs of space for work and circulation in the space. while the workplace with a non-cubical layout has a distance between tables of 1 m and without borders. virus transmission will become easier. based on information from the office manager, employee who infected the coronavirus is who sit under or in front of an ac source. during the covid 19 pandemic, in a workplace with a non-cubical concept, several residents were found to be positive for covid 19. then the manager took a work from home policy to reduce the number of occupants in one room every day and use barriers between tables. the use of a barrier between work desks is recommended by kemenkes ri (2020) to prevent the transmission of the covid 19 virus in the workplace. health protection health protection is carried out by all of workplaces. before entering the workplace, residents must wash their hands, check body temperature and wear masks. while in the room, residents must wear masks and use hand sanitizer after handling objects. workplaces are sprayed with disinfectant at least once a week to prevent the spread of coronavirus. all health protection in the workplace has been carried out in accordance with recommendations from the indonesian ministry of health (2020). indoor and health comfort analysis of indoor and health comfort based on employee perceptions from a questionnaire survey. there are five variables asked to respondents. the results of the analysis show that lighting has a mean value of 3.19; ventilation has a mean value of 3.20; thermal and humidity have a mean value of 2.99; distance has a mean value of 3.75 and health protection has a mean value of 4.23 (table 1). this shows that health protection and distance of workbench are prioritized in the workplace to support workplace comfort. 167 journal of sustainable architecture and civil engineering 2023/1/32 in the indoor health and comfort workplace there are five variables, namely lighting, ventilation, thermal and humidity, distance of workbench and health protection (table 2). lighting ventilation thermal distance health protection mean 3.19 3.20 2.99 3.75 4.23 table 1 mean value source: analysis table 2 indoor health and comfort analysis variables mean lighting maximizes the use of natural lighting 3.32 a workplace has many glass openings in every part of the room 3.31 the light in the workplace is uncomfortable/glare in the morning making it difficult for occupant to focus on the screen 2.28 too much natural light in the workplace 2.53 occupant needs natural light from outside 4.12 workplaces rely on artificial lighting (eg lamps) 3.58 ventilation workplace has window/ventilation to enter clean air into the workspace 3.48 clean air in the workplace is not enough 2.98 the air in the workplace feels stuffy 2.41 ventilation in the workplace is not effective 2.80 every 4 hours or so the windows in the workplace must be opened to intake clean air 3.38 door in workplace must be opened to intake clean air 3.33 toilet has ventilation 3.86 thermal and humidity the air temperature in the workplace is too hot 2.26 the air temperature in the workplace is too cold 2.70 the air temperature in the workplace can be controlled 4.12 workplace uses central air conditioning 2.88 distance the work table has a minimum distance of 1 meter 4.00 cubical work table 3.50 the work table has a divider 3.54 there is a limitation on the number of people in a closed room 3.96 health protection work from home (wfh) 3.91 wash hand 4.50 checks body temperature 4.37 masker 4.67 hand sanitizer 4.72 take advantage of lunch time to breathe fresh air outdoors 4.20 disinfectan in workplace 3.25 source: analysis journal of sustainable architecture and civil engineering 2023/1/32 168 in lighting, respondents need natural light from outside in addition to using artificial lighting in the room. sunlight can be entered through the provision of windows. however, it is necessary to consider the dimensions of the window so that the light entering the room does not cause glare in the room. the use of artificial lighting must adjust to the level of lighting or lux. according to gbci (2018), optimization of lighting in the workplace can be adjusted to the layout of the work desk and the placement of light points. in ventilation, respondents want the ventilation to be opened to enter fresh air from outside into the workplace, including the toilet. the placement of doors and windows that can be opened can adopt a cross-ventilation system so that air can enter all parts of the workplace. regarding thermal and humidity, respondents stated that the air temperature in the workplace should be controlled. in a workplace with a centralized ac system, the air temperature is set centrally. standard air temperature is 24◦c 27◦c with a relative humidity of 60% (gbci). the workplace should not be too cold so that users feel comfortable and electricity consumption is not wasteful. the placement of the work table should not be directly under or facing the direction of the wind from the air conditioner. in the distance of workbench, respondents want a cubical workbench or use a barrier with a minimum distance of 1 meter between tables. the divider between work desks can reduce physical contact and the spread of the virus between employees. then the number of people in the workplace should be limited. circulation paths in the workplace should be wider so that when employees pass each other they can keep their distance. health protection efforts in the workplace must be carried out, for example by providing a place to wash hands, occupants using masks in the room, having hand sanitizers on each workbench and periodically spraying the workplace with disinfectant. adaptive workplace layout design based on the results of the analysis, an adaptive workplace that supports a sustainable city is that prioritizes indoor health and comfort. workplace layout design should consider health and comfort in the room, work desk settings, and health protection. an open workplace must be managed by using a divider on each workbench. the distance between the work table and circulation in the room should be considered so that it meets the established physical distancing requirements. ventilation for air circulation ventilation for air circulation divider between tables indoor plant a workplace that arranges desks in a row is a flexible space. in the workplace, work activities, team meetings, and discussions can be carried out. in cubical workplaces, work activities are carried out in each cubicle. meetings are held in the meeting room. the meeting rooms provided are flexible because they are used for small and large capacities (fig. 4). the provision of flexible space is following research from konieczna (2018) which states that in adaptive architecture there is a level of flexibility, where adaptation to space is controlled directly by humans. the room can be used for various activities, enlarged or narrowed by using hinges, rails, and bearings on the room divide. air quality is an important thing in space. the exchange of air in the room can be done by making cross ventilation and opening windows periodically to get fresh air. setting a temperature between 17-28◦c and humidfig. 4 workplace layout with cubical concept 169 journal of sustainable architecture and civil engineering 2023/1/32 indoor plant ventilation for air circulation ventilation for air circulation divider between tables ity 40%-70% in the room is recommended according to ashrae (2020). the addition of plants in the room can help absorb co2. the distance between the workbench should be at least 1 meter by using a barrier between the workbench. in a workplace with a cubical layout, the desk divider can be a screen between the desks (fig. 4). in a workplace with a non-cubical layout, the seating arrangements between work desks can be arranged in a zig-zag or unequal manner and between desks (fig. 5). circulation in the room fig. 5 workplace layout with noncubical concept should be wider than before the covid 19 pandemic. the corridors in the workplace should have a minimum width of 1.2 1.5 meters and avoid two-way traffic (nediari, et al., 2021). the application of health protection such as periodically disinfecting the workplace, washing hands before entering the workplace, measuring temperature, and using masks in the workplace, is highly recommended to become a habit at this time, according to instructions from kemenkes ri (2020). design considerations with an indoor health and comfort approach can provide a sustainable and comfortable design for residents. this design can be applied to the post-pandemic covid 19 thereby reducing the spread of the virus in the workplace (nediari et al., 2021) and improving the performance of its occupants (vgbc, 2019). conclusion indoor health and comfort is one of the principles in green buildings. this principle aims to provide a comfortable and healthy indoor space. the workplace layout design concept is based on data collection by means of observation to obtain workplace conditions based on the location of ventilation, use of natural and artificial air, lighting, the layout of the furniture and applied health protection. in addition, employees provide their perceptions through questionnaires regarding the implementation of indoor health and comfort in the workplace. a workplace that meets the principles of indoor health and comfort can improve the performance of its occupants and reduce the spread of viruses in the space. workplaces during the post-covid-19 pandemic require adaptation. air quality regulation and workplace layout are important concerns to suppress the spread of the virus and improve occupant health. setting the distance between the work desk and the seat should be at least 1.2 meter by providing a barrier on each work desk. workplace ventilation is used to change the air in the room and enter sunlight into the space. indoor air must flow so that indoor air conditions are maintained. health protection is carried out before occupants enter the workplace and when in the workplace. based on the results of user observations and perceptions, an adaptive workplace layout design can be developed that meets indoor health and comfort standards and meets the needs of employees as users. adaptation of the workplace layout related to the concept of sustainability. this adaptation effort aims to provide a healthy and hygienic workplace. office buildings should prepare a workplace that is not only concerned with space efficiency but also provides a healthy and comfortable indoor journal of sustainable architecture and civil engineering 2023/1/32 170 space. this has an impact on productivity and work comfort for residents. but all these efforts must be supported by the new normal behaviors of space users. the workplace layout design is expected to be a model for the workplace in office buildings. funding the research does not receive external funding. acknowledgment author would like to thank to all office managers and respondents who have helped the process of collecting data in this research. ashrae. (2020). updated ashrae® recommendations for covid-19, providing insights for today’s hvac system designer. engineers newsletter. vol. 49-2. https://www.tranehk.com/files/news/engrnewsletter/trane%20engineers%20newsletter_ vol49_2.pdf. accessed 18 march 2021. demers, claude, andré potvin, dan hélène giguère-duval. (2014). inhabiting adaptive architecture: environmental delight in adaptable spaces. proceeding of international conference on adaptation and movement in architecture (icama2013). ecdc. (2020). heating, ventilation and air-conditioning systems in the context of covid-19: first update. european centre for disease prevention and control. 10 november 2020. stockholm: ecdc, online available, https://www.ecdc.europa. eu/sites/default/files/documents/heating-ventilation-air-conditioning-systems-in-the-con text-of-covid-19-first-update.pdf, accessed 8 march 2021. fachrudin h. t., fachrudin k. a. (2021). factors influencing energy conservation application in green campus design based on green behavior. international journal of energy economics and policy. vol. 11. no. 4. pp.511-520. https://doi.org/10.32479/ ijeep.11355 fachrudin h. t., fachrudin k. a., pane i. f., (2022). workplace design concept based on indoor environmental quality analysis to prevent coronavirus transmission, civil engineering and architecture, vol. 10, no. 1, pp. 121 130, 2022. https://doi. org/10.13189/cea.2022.100111 gbci. (2016). greenship existing building version 1.1, divisi rating dan teknologi green building council indonesia. green building council indonesia. juni 2016, www.gbcindonesia.org . gbci. (2018). greenship new building version 1.2, divisi rating dan teknologi green building council indonesia. green building council indonesia. november 2018. references gbi index. (2011). green building index assessment criteria for nreb, first edition, version 1.1. greenbuildingindex sdn bhd (845666-v).. https:// www.greenbuildingindex.org/files/resources/ gbi%20tools/gbi%20nreb%20nonresidential%20existing%20building%20tool%20v1.1%20 final.pdf. accessed 12 april 2021. gou z. (2016). green building for office interiors: challenges and opportunities. facilities. vol. 34. no. 11/12. pp. 614-629. emerald group publishing limited 0263-2772. https://doi.org/10.1108/f-04-2015-0022 guo m., xu p., xiao t., he r., dai m., miller s. l. (2021). review and comparison of hvac operation guidelines in different countries during the covid-19 pandemic. building and environment. 187. 107368. https://doi.org/10.1016/j.buildenv.2020.107368 kaushik m., guleria n. (2020). the impact of pandemic covid -19 in workplace. european journal of business and management. vol. 12. no.15. 2020. kemenkes ri. (2020). keputusan menteri kesehatan republik indonesia nomor hk.01.07/ menkes/328/2020. panduan tentang pencegahan dan pengendalian corona virus disease 2019 (covid-19) di tempat kerja perkantoran dan industri dalam mendukung keberlangsungan usaha pada situasi pandemi. [decree of the minister of health of the republic of indonesia number hk.01.07/ menkes/328/2020. guidelines on prevention and control of corona virus disease 2019 (covid-19) in office and industrial workplaces in supporting business continuity in pandemic situations]. http:// hukor.kemkes.go.id/uploads/produk_hukum/ kmk_no__hk_01_07-menkes-328-2020_ttg_ panduan_pencegahan_pengendalian_covid-19_ di_perkantoran_dan_industri.pdf, accessed 8 march 2021. nakib f. 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(2019). lotus buildings in operation v1, technical manual, lotus bio v1 updated version technical manual september 2019. https://vgbc. vn/en/lotus-bio/, accessed 16 april 2021. wardhani d. k., susan, anastasia m., setiando m. j. (2020). indoor health and comfort for the green workplace at university. arteks, jurnal teknik arsitektur. vol. 5. issue 3. december 2020. https://doi. org/10.30822/arteks.v5i3.582 about the authorhilma tamiami fachrudin lecturer department of architecture, faculty of engineering, universitas sumatera utara main research area architecture and urban design address jalan perpustakaan, gedung j07, kampus usu, medan, indonesia tel. +6281376998695 e-mail: hilma@usu.ac.id this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). journal of sustainable architecture and civil engineering 2022/1/30 142 this study investigates the impact of window-to-wall ratio (wwr) and shading coefficients (sc) as passive design strategies to optimise daylight in an opaque brick double-skin façade (dsf) of an education building in depok, indonesia. a sample education building was simulated with dialux software for calculating the daylight distribution due to wwr on a daily basis during normal office hours. the optimum amount of window size and glazing were investigated for a typical floor plate area of 315.16m2. wwr was considered from 30% to 60% at 10% intervals in a horizontal and vertical expanding method of window. the simulations were performed in two sky conditions (sunny sky and standard cie overcast sky) on different dates using glazing material of different sc. the primary findings of this study are that 40% wwr with sc 0.42 and 60% wwr with sc 0.95 achieve the best results for the north and south façade respectively of a dsf building. keywords: daylight performance, double skin façade, shading coefficient, window-to-wall ratio. window-to-wall ratio as a mode of daylight optimization for an educational building with opaque double-skin façadereceived 2021/09/07 accepted after revision 2022/02/01 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 142-152 doi 10.5755/j01.sace.30.1.29744 window-towall ratio as a mode of daylight optimization for an educational building with opaque doubleskin façade jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.29744 ova candra dewi, kartika rahmasari, tika ardina hanjani department of architecture, faculty of engineering, universitas indonesia, kampus baru – ui depok, 16424, indonesia agust danang ismoyo department of technic architecture, faculty of engineering, university of mercu buana, kembangan – meruya, 11650, indonesia amardeep m. dugar lighting research and design, chennai 600102 tn, india introduction *corresponding author: amdugar@lighting-rnd.in abstract the department of energy states that lighting consumes about 25% of all the electricity consumed by buildings and 40% by commercial buildings (iea 2010; “data & statistics iea” n.d.). however, about half of all that electricity can be saved with the use of appropriate daylight strategies (lechner 2015). a rational use of daylight significantly reduces the energy used for electric lighting (burmaka et al. 2020). a study indicates that a 40% reduction in lighting energy consumption can reduce the overall energy consumption by 17% (tsangrassoulis et al. 2017) appropriate daylight strategies enable the capture and delivery of daylight deep inside interior spaces (ullah 2019). for this reason, daylight should be considered as a replacement for electric light as well as the reduction of energy usage for lighting (iea 2010). electric lighting is a controllable man-made 143 journal of sustainable architecture and civil engineering 2022/1/30 source that is easier to both study and engineer for achieving specific outcomes. daylight however is a natural source that is more difficult to control considering its daily and annual dynamics, which produce different outcomes in different locations and weather conditions (knoop et al. 2020). daylight admitted into interior spaces via building openings to replace or supplement electric lighting is used as a passive strategy to reduce energy consumption from electric lighting (chi et al. 2018). daylighting with appropriate window shape, size in terms of wwr, and glazing can also significantly reduce the need for electric lighting as well as provide comfort and energy savings in buildings (alhagla et al. 2019; zazzini et al. 2020). while high illuminance and colour identification provided by daylight enhance conditions for vision, it can also produce high luminance reflections on display screens and solar glare discomfort (mahdavi et al. 2013). a study reports that the electrical energy used for lighting in the asean countries (indonesia, malaysia, philippines, singapore, and thailand) is about 20% to 24% of the total energy consumption in education buildings (cammarano et al. 2015). additionally, a study dealing with daylight in tropical areas indicates that most occupants prefer working under daylight (hirning et al. 2017). therefore, utilization of daylight in the context of energy savings also covers for visual needs (“data & statistics iea” n.d.; dilaura and houser 2011). however, most education buildings are dependent more on electric lighting despite the fact that energy savings between 20-70% can be achieved through daylight. double skin façade (dsf) plays an essential role in providing an environmental solution to climatic conditions where facades influence the daylight illuminance (chi et al. 2018). dsfs are used as a passive strategy to moderate indoor conditions of hot climates (zazzini et al. 2020). dsf as the outer skin with different materials ranges from fully glazed to opaque façades that absorb and reflect solar radiation (barbosa and alberto 2019). dsfs can minimize heat exchanges between the indoor and outdoor environments, thereby being useful in tropical climates (halawa et al. 2018). the opaque external dsf layer works as a solar protection panel, which allows this application without shading devices (barbosa and alberto 2019). as dsf usage might lead to a reduction of the quantity of daylight entering into space it is highly related to the window size (moscoso et al. 2021). daylight penetration from windows results in non-uniform spatial distribution of illuminance where high illuminance is experienced on areas next to openings, which then decreases progressively towards peripheral walls (zazzini et al. 2020). the fenestration system should consider window shape, window-to-wall ratio (wwr), and glazing type as higher wwr can provide higher illuminance and better daylight distribution within the room (alhagla et al. 2019). sometimes, even the shape and orientation of the glazing may lead to different wwr needs (shameri et al. 2011; iea 2010). although lighting in a space via daylight penetration can be uniformly distributed with the appropriate use of wwr, inappropriately planned daylight can also become a source of excessive heat gain (kontadakis et al. 2017). shading coefficient (sc), which is defined as the solar radiation ratio with solar protection to solar radiation without solar protection, has been used to represent the solar shading performance of glazed areas (gordon 2014; lechner 2015). this implies that glazing materials and orientation play a significant role in providing broad daylight yet avoiding solar radiation that may increase energy usage. when daylight illuminates transparent materials, light is partially absorbed, reflected, and transmitted on both sides of the glazing surface (liébard and herde 2008). due to these geographical differences, appropriate use of daylight can vary from sun and skylight exposure. a study reports that daylight in tropical areas can be optimized when the wwr ranges between 25-35% without installing a dsf (mahdavi et al. 2013). however, the average wwr required for a single-skin facade in tropical areas ranges between 25-50% (pemerintah provinsi dki jakarta 2012). another study reports that the most optimum solution with the least mean distance to the utopia points is the combination of wwr 30%, wall reflectance of 0.8, and south orientation in tropical area (mangkuto et al. 2016). wwr performances depend on numerous parameters such journal of sustainable architecture and civil engineering 2022/1/30 144 as window dimensions, external climatic conditions in terms of clear or overcast skies, and glazing materials (zazzini et al. 2020; lechner 2015). however the reasons for using daylight in architecture extend from those of a practical nature, including energy conservation, cost factors, and health and wellbeing, to those of a more intangible, aesthetic nature (richard 2009). this study aims to investigate the impact of wwr and sc as passive design strategies to optimise daylight in an opaque dsf of an education building in depok, indonesia. methods research framework the research workflow and methodology applied in this study is by simulation using relevant software as shown in figure 1. the simulations were conducted in dialux software developed by dial on a model that represents the first-floor area of an educational building. dialux utilizes radiosity as the simulation algorithm, which can be applied to validate lighting simulations that show very good agreement with the reference values in cases with a point source of light (davoodi 2016; mangkuto 2016). dialux can easily and efficiently predict the daylight illuminance and its consequences in any building irrespective of its construction (ahmad et al. 2020). the algorithm validation (castillo-martinez et al. 2017) and accuracy of prior versions of dialux have been verified against the analytical test cases of cie 1717:2006 (mangkuto 2016). a study also concludes that dialux 4.8 shows a margin of relative error lower than 30% in all case studies for traditional and standard cie overcast skies (acosta et al. 2015). parametric modelling on existing data was conducted with parametric variables such as existing sc, wwr and sky condition to understand the existing condition without a reflective device to enable daylight further penetration into the room corner. after the initial data investigation, different scenarios are proposed with multiple combinations of sc and wwr to arrive at the most effective condition. the study limits its scope only to sc and wwr of dsf, hence other devices such as interior ceiling reflectors are not considered in the simulations. fig. 1 research framework: daylight optimization process and tools simulation setting the simulation model is based on an educational building with a secondary opaque facade built-in 2015, as shown in figure 2. opaque facade is used as the primary building material for the facade to prevent excessive heat gain and act as a shading device. within this study, five stories of secondary opaque facade models with different orientations, window to wall ratio percentages, and different light transmittance glass were used. each opaque module is 10m2 with spaces about 0,277 m among each module to let the daylight in. between the wall and the secondary facade, there is an unconditional space of 1.35m in figure 3. according to the sun path diagram in indonesia, sun position will change every half a year in the north and south side periodically as shown in figure 3. therefore simulation runs were carried 145 journal of sustainable architecture and civil engineering 2022/1/30 fig. 2 nano technology laboratory for higher education in depok, indonesia out for depok (357°n, 6° 21’ 41’ ‘ s and 106°49’30” e) at 10 am on 21st march, 21st june and 21st december with two models facing north and south facade based on its sun path as shown in figure 4. additionally the dynamic nature of the indonesian sky causes daylight conditions to change rapidly in a short span of time. therefore each model was simulated under two different skies: the standard cie overcast sky and sunny sky, during summer and winter solstice with several wwr and glazing sc in northand south-facing facade orientations. tropical areas typically receive long sun hours and massive amounts of daylight throughout the year, where each direction can receive equal amounts of light as others: a north window can receive as much light as a south window (lechner 2015). the typical floor plate used in this simulation is the first floor focusing on two areas: the north-facing floor with an area of 164.2m2 and the south-facing floor with an area of fig. 3 façade details: (a) elevation (b) section (a) (b) journal of sustainable architecture and civil engineering 2022/1/30 146 fig. 4 sun path diagram on a) december 21st, b) march 21st, and c) june 21st at 13am fig. 5 first floor layout plan from the selected model comprising laboratories and meeting room with total area of 315.15m2 table 1 calculated building parameters 150.96m2, as shown in figure 5. single glazing material with clear sc 0.95 and reflective sc 0.42 are used in this study since it has a secondary facade with a 1.3m gap to reduce solar radiation between its skin to absorb, reflect and transmit daylight. these two glazing materials are based on jakarta’s governor regulation no. 38/2012 vol.1 (pemerintah provinsi dki jakarta 2012). (a) (b) (c) a series of simulations using dialux software were performed in two sky conditions (cie overcast sky and sunny sky) with height calculation parameter of 0.8m and setting of the area as parameter ceiling height (m) wall thickness (m) surface reflection coefficient of ceiling / wall / floor value 3.8 0.12 0.7 / 0.5 / 0.1 shown in table 1. the outcomes acquired from 32 simulations were analysed and categorized as shown in table 2. according to indonesian national standard (sni), average illuminance (eavg) of 250 lux was considered for a visual task carried out in educational buildings and 500 lux for a laboratory (sni 2004). the amount of daylight received was classified based on user-defined illuminance threshold intervals of three categories such as insufficient if less than 250 lux, sufficient if in the range of 251-500 lux, and excessive if more than 500 lux. 147 journal of sustainable architecture and civil engineering 2022/1/30 the first sets of simulations were performed using the existing building condition. in order to determine the optimum percentages of sc and wwr, at first both north and south facades were considered 25% as per the existing condition and the daylight illuminance was determined. then the percentage of wwr was changed starting from 30% up to 60% with a 10% step interval (shaeri et al. 2019). the lower limit was set at 30% wwr considering the fact that the existing building with 25% wwr had low daylight penetration. the upper limit was set at 60% wwr to avoid glare and heat gain from excessive daylight. the second sets of simulation were conducted using single glazing materials of clear sc 0.95 and reflective sc 0.42. the results were then compared based on the wwr effects under the sunny sky and cie overcast sky for daylight optimization. existing condition the simulation result for the existing condition performed under a sunny sky and cie overcast sky show that despite 25% wwr with single glazing of sc 0.95, daylight penetration was low due to the secondary facade influence. the illuminance on both northand south-facing sides of the floor do not meet the required minimum standards for eavg, as shown in figure 6, and table 2. studies reveal that simulated values of eavg for overcast skies can vary considerably due to the refraction and scattering of daylight (kondáš, and darula, 2014; kensek and suk, 2011). results (b) cie sunny sky on 21st december sc = 0.95, wwr = 25% (c) cie overcast on 21st june sc = 0.95, wwr = 25% (d) cie overcast on 21st december sc = 0.95, wwr =25% (a) cie sunny sky on 21st june sc = 0.95, wwr = 25% fig. 6 daylight simulation for existing condition table 2 existing scenario with sc 0.95 and 25% wwr sc – orientation wwr eavg overcast (lx) eavg sunny (lx) march june dec march june dec 0.95 – north 25% 69.1 85.9 94.2 46.9 628 71.6 0.95 – south 25% 70.9 99 109 278 772 182 journal of sustainable architecture and civil engineering 2022/1/30 148 proposed conditions the simulation results using different wwr with sc 0.42 as shown in figure 7 and table 3, and sc 0.95 as shown in figure 8 and table 4 vary due to the tropical sun path e.g. eavg lowering at 35% wwr and reaching excessively high levels for the north orientation. under the sunny sky condition, the eavg achieved with sc 0.42 on north-facing floor in june with 60% wwr is 473.7 lux meeting the comfortable standard. however, the south-facing floor is not able to meet the illuminance standard even with 60% wwr. conversely, under cie overcast sky conditions the eavg achieved do not meet the minimum standards under any wwr. sc – orientation wwr eavg overcast (lx) eavg sunny (lx) march june dec march june dec 0.42 – north 30% 45.4 41.7 45.7 51.4 331 34.9 40% 138 122 130 126 506 98.6 50% 149 129 142 145 609 107 60% 157.9 156.6 162 163.4 731 147 0.42 – south 30% 65.8 49.2 54 59.7 38.7 85.2 40% 136 120 129 125 484 98.1 50% 163 141 155 129 511 241 60% 171.6 170 176 164.1 554.9 248 table 3 proposed scenarios with sc 0.42 and different wwr fig. 7 comparison of eavg a) north orientation and b) south orientation with sc 0.42 (a) (b) sc – orientation wwr eavg overcast (lx) eavg sunny (lx) march june dec march june dec 0.95 – north 30% 106 92.4 101 106 728 77.1 40% 137 121 130 134 506 98.6 50% 149 129 142 145 913 107 60% 140 122 134 136 934 101 0.95 – south 30% 122 106 117 97.3 83.1 195 40% 151 134 144 120 104 213 50% 163 141 155 129 111 241 60% 183 159 175 147 126 287 table 4 proposed scenarios with sc 0.95 and different wwr 149 journal of sustainable architecture and civil engineering 2022/1/30 fig. 8 comparison of eavg a) north orientation and b) south orientation with sc 0.95 (a) (b) under the sunny sky condition, the eavg achieved with sc 0.95 on the north-facing floor in june for most wwr are in excess of 900 lux thereby causing glare. however, on the south-facing floor in december with 60% wwr, this material provides 154 lux, which is insufficient for the user as shown in figure 8. conversely, under cie overcast sky conditions with 60% wwr, the highest eavg achieved is 176 lux on the south-facing floor during december, while on the north-facing floor it is 162 lux. both these outcomes do not provide sufficient illuminance for the user. discussion sc – orientation wwr eavg overcast (lx) eavg sunny (lx) march june dec march june dec 0.42 – north 40% 138 122 130 126 506 98.6 0.95 – south 60% 183 159 175 147 126 287 table 5 proposed scenario with mixed-usage of sc and wwr as investigated and documented in this study, the eavg in an existing education building with an opaque dsf having 25% wwr do not meet sufficient illuminance standards. therefore, various combinations of sc and wwr have been applied by simulation to arrive at the most suitable fenestration detail for a building with an opaque dsf. table 5 shows the results of a proposed mixeduse scenario of glazing and wwr. a 40% wwr is more effective for daylight optimization on the north-facing facade during sunny sky conditions because it produces less direct glare compared to wwr 50% and 60%. similarly, a 60% wwr is more effective for daylight optimization on the south-facing facade during overcast sky conditions as it maximises the amount of daylight entering the space. application of reflective glazing with sc 0.42 on the north-facing facade produces more uniform daylight and recorded 506 lux in june. application of clear glazing with sc 0.95 produces more uniform daylight on the south-facing facade and recorded 126 lux in june. therefore, the following mixed usage combination of clear and reflective glazing materials along with wwr is proposed to optimize the building’s effective exposure to the sun: _ north-facing facade – 40% wwr with reflective glazing sc 0.42 _ south-facing facade – 60% wwr with clear glazing sc 0.95 the above results support the study (nordin et al. 2019) that although a higher range of wwr with 40% at north-facing facade and 60% at south-facing facade may produce glare, the secondary facade is able to filter excessive light radiation and consequent heat gain. however, supplemental electric lighting will be required in this building to meet the minimum illuminance standard especially during overcast sky conditions. this shows that although sc and wwr can mitigate journal of sustainable architecture and civil engineering 2022/1/30 150 lighting-related energy requirements, education buildings still have to depend on supplemental electric lighting. additionally, although window height is important to provide a higher illuminance (sánchez-tocino et al. 2019), in case of different heights of room and materials used for the secondary façade, the outcome may vary. architects and planners in order to reduce energy gain from sun radiation generally tend to use fenestration details that at some point can block daylight out completely. this study shows that secondary opaque dsfs with an appropriate combination of sc and wwr can be used as a fenestration detail in tropical climatic conditions to optimize daylight and reduce energy usage along with adding to reasons of aesthetics, health and wellbeing. daylight can be creatively harnessed with a fenestration detail that combines sc and wwr to improve the aesthetics and energy performance of buildings. however, daylight cannot be used as a sole source of illumination even in tropical regions as this study shows that supplemental illumination might be required in the form of electric lighting during certain times of year. additionally, it is important to note the various limitations of this study: firstly, the generalizability of this study requires further exploration; secondly, this study limits the interference of human behaviour towards lighting use that may impact its energy use; thirdly, other external factors that may interfere with the amount of daylight received were not considered in this study. therefore further research is required in other types of secondary facades that will provide further guidance for daylight design in tropical areas. acknowledgment all authors contributed equally in the preparation of this manuscript. the authors gratefully acknowledge support from the department architecture, faculty of engineering, universitas indonesia, especially dr. toga h. panjaitan. the authors thank bayu ariaji wicaksono and herdinal muhammad boer for support in undertaking the preliminary study. the authors also thank the anonymous reviewers for their valuable comments. conclusions acosta, i., muñoz, c., esquivias, p., moreno, d., and navarro, j. september 2015. “analysis of the accuracy of the sky component calculation in daylighting simulation programs”. solar energy 119:54-67. https://doi.org/10.1016/j.solener.2015.06.022 ahmad, asim, anil kumar, om prakash, and ankish aman. 2020. “daylight availability assessment and the application of energy simulation software a literature review.” materials science for energy technologies 3: 679-89. 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i. alonso alonso, a. vallelado alvarez, m. garcía zamora, e. francés caballero, m. marcos-fernández, s. schellini, and a. galindo-ferreiro. 2019. “the effect of light and outdoor activity in natural lighting on the progression of myopia in children.” journal francais d’ophtalmologie 42, no. 1: 2-10. https://doi.org/10.1016/j.jfo.2018.05.008 shaeri, j., habibi a., yaghoubi m. and chokhachian, journal of sustainable architecture and civil engineering 2022/1/30 152 a. 2019. “the optimum window-to-wall ratio in office buildings for hot-humid, hot-dry, and cold climates in iran.” environments 6 (4) 45. https://doi. org/10.3390/environments6040045 shameri, m. a., m. a. alghoul, k. sopian, m. fauzi m. zain, and omkalthum elayeb. 2011. “perspectives of double skin façade systems in buildings and energy saving.” renewable and sustainable energy reviews 15, no. 3: 1468-75. https://doi.org/10.1016/j. rser.2010.10.016 sni. 2004. sni 16-7.62-2004 : pengukuran intensitas penerangan di tempat kerja. tsangrassoulis, a., a. kontadakis, and l. doulos. 2017. “assessing lighting energy saving potential from daylight harvesting in office buildings based on code compliance & simulation techniques: a comparison.” procedia environmental sciences 38: 420-27. https://doi.org/10.1016/j. proenv.2017.03.127 ullah, irfan. 2019. “heliostats daylighting system for multi-floor buildings.” journal of daylighting 6, no. 2: 202-9. https://doi.org/10.15627/jd.2019.18 zazzini, paolo, alessandro romano, alessio di lorenzo, valeria portaluri, and alessandro di crescenzo. 2020. “experimental analysis of the performance of light shelves in different geometrical configurations through the scale model approach.” journal of daylighting 7, no. 1: 37-56. https://doi. org/10.15627/jd.2020.4 about the authors ova candra dewi lecturer department of architecture, faculty of engineering, universitas indonesia main research area architecture and sustainability address kampus baru ui depok, indonesia 16424 tel. +62217863514 e-mail: ova.candewi@ui.ac.id this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). kartika rahmasari postgraduate student department of architecture faculty of engineering, universitas indonesia main research area architecture and sustainability address kampus baru ui depok, indonesia 16424 tel. +62217863514 e-mail: kartika.rahmasari@ui.ac.id tika ardina hanjani postgraduate student department of architecture, faculty of engineering, universitas indonesia main research area architecture and sustainability address kampus baru ui depok, indonesia 16424 tel. +62217863514 e-mail: tika.ardina@ui.ac.id agust danang ismoyo lecturer department of technic architecture, faculty of engineering, universitas mercu buana main research area lighting design address kembangan meruya, indonesia 16650 tel. +628161132228 e-mail: agustdanang@gmail.com amardeep m. dugar founder and principal lighting research & design main research area lighting design and sustainability address flat-3 bhavana apartment, f-142 8th cross street, anna nagar (east), chennai india 600 102 tel. +919445549567 e-mail: amdugar@lighting-rnd.in 43 journal of sustainable architecture and civil engineering 2019/2/25 *corresponding author: anne.g.lien@sintef.no costs and procurement for cross-laminated timber in mid-rise buildings received 2018/12/11 accepted after revision 2019/02/25 journal of sustainable architecture and civil engineering vol. 2 / no. 25 / 2019 pp. 43-52 doi 10.5755/j01.sace.25.2.22099 costs and procurement for cross-laminated timber in mid-rise buildings jsace 2/25 http://dx.doi.org/10.5755/j01.sace.25.2.22099 anne gunnarshaug lien*, nicola lolli sintef building and infrastructure, norway introduction the objective of this paper is to report on and analyse strategies for cost reduction, design processes and procurement models of a wooden nearly zero energy building (nzeb) in norway. this publication is part of the dissemination activities of the eu horizon 2020 project nero, whose scope is to demonstrate the feasibility of cost reduction of nzebs built in wood in the nordic countries. case buildings from estonia, finland, norway and sweden are studied with respect to their technological solutions, energy use and construction cost. the norwegian building investigated in this paper is the moholt allmenning, a newly built student accommodation located in moholt, trondheim. interviews with the building’s owner and the contractor were carried out to obtain information on the decision-making process during the procurement phase, the planning phase and the execution phase. the results show that the environmental goal and the requirement for the use of wood set out in the tender announcement were decisive driving forces for the selection of cross-laminated timber (clt) in the final design. the results also show that the cost of using clt in student residences is competitive when compared to using concrete and steel. given the requirement for minimal greenhouse gas (ghg) emissions from materials production in nzebs, the use of clt is, however, a better choice. keywords: clt, cross-laminated timber, nzeb, procurement, ghg emissions, architecture competition the moholt allmenning was commissioned by sit (studentsamskipnaden i gjøvik, ålesund and trondheim) in 2013 through a design competition named moholt 50/50. sit is a student welfare organisation that plan, build and run student accommodations. the moholt allmenning (moholt 50-50 trondheim) is an extension of the old moholt student residence complex in trondheim, see fig. 1. the new construction consists of five nine-storey towers. each floor typically accommodates 15 residential units, with a total of 632 units. located on the five ground levels are a healthcare centre, fitness centre, hairdresser, shared laundry and an international food shop. the new complex also hosts a kindergarten for 171 children as well as an activity centre with public library. the student rooms include private bathrooms and are organised in a y-shaped layout around the common area/kitchen/dining area. the towers are built with cross-laminated timber (clt) as load-bearing systems. inside, the wood surfaces are exposed and are clearly visible in the student apartments. the building’s energy efficiency solutions were designed to comply with the norwegian passive house standard (ns 3700, 2013). journal of sustainable architecture and civil engineering 2019/2/25 44 wooden nearly zero energy buildings (nzebs) in norway norway is yet to specify nearly zero energy buildings (nzebs) (directive 2010/31/eu, 2010) as a target for the energy performance of norwegian buildings. the most ambitious energy performance target for buildings, available in the norwegian regulations so far, is the norwegian passive house standard (ns 3700, 2013). this standard specified a slightly more ambitious building energy performance target than that of the currently enforced norwegian building code (tek17). other benchmarks that define building energy performance and environmental goals are available, such as breeam-nor and zero emission building (zeb). the latter specifically targets the buildings’ lifecycle greenhouse gas (ghg) emissions due to the energy use from the production of the building materials up to and including the buildings’ demolition. given the lack of a norwegian definition of nzebs, the labelling (in terms of energy) of the moholt allmenning is therefore compared to the requirements set in tek17. the energy meter from one of the residential towers of the moholt allmenning shows that the building used 80 kwh/m2 in 2017. this includes electricity for heating, domestic hot water, lighting, appliances, ventilation and water pumps. since the moholt allmenning uses less energy than the limits defined in tek17 (which is set to 95 kwh/m2y for residential buildings), the building is placed in energy class a, according to the norwegian energy classification (energimerking). the use of wood in building construction has a significant potential for reducing ghg emissions (skullestad et al. 2016, skaar et al. 2017, malmqvist et al. 2018, østnor et al. 2018). moreover, the benefits of urban densification in terms of reduced lifecycle ghg emissions for transport and building construction is undoubted (bergesen et al. 2017, göswein et al. 2017, fercovic and gulati 2016). in this respect, the current norwegian building industry is investigating the opportunities for combining the goals of urban densification with the use of wood in building construction. the recent construction of a mixed-used tower (residential, hotel, swimming pool, offices, restaurants) that is 80 metres high with 18 floors in mjøsa – being erected with clt and glulam elements – sets a new benchmark for the use of engineered wood in building construction (mjøstårnet, moelven). the shift from concrete to wood in the norwegian building industry requires a tremendous effort in order to be realised. currently, the concrete industry is responsible for the majority of large constructions being erected in norway as a result of installing concrete floors in 70% and 45% of non-residential buildings and apartment buildings, respectively (betongelement foreningen 2017). wooden elements are mostly used for frames of small buildings (such as single-family houses and cabins), frames of non-load-bearing facades and for cladding (treindustrien.no). the use of wood in large buildings also requires additional safety and attention with respect to fire safety and noise propagation; this is likely to introduce additional cost to the building process in order to satisfy the current building requirements (structural timber association 2014, buchanan et al. 2014, hoeller et at. 2017, pagnoncelli and morales 2016). the aim of this work is to give an insight into the decision-making process before and during the construction of the moholt allmenning. special focus is given to the procurement route and the cost reduction strategies used in the process. this work is part of the horizon 2020 nero project, which “develops and demonstrates nearly zero energy wood buildings design processes and procurement models with reduced cost for large-scale use in the northern climatic conditions and on performance level of near zero and beyond” (nero wood for zero). the objective of the nero project implies that the choice of design process and procurement model influences the final cost of a wooden nzeb building. the work presented in this paper aims at finding what type of relationship exists between the design process, the procurement model and the final cost of the building. methods structured interviews were carried out with the stakeholders of the moholt allmenning during the autumn of 2018. at that time, the buildings had been occupied for two years. three interviews were carried out: two with the building owner, sit, and one with the contractor. from sit, the head of project development (1) and the project leader for moholt allmenning (2) were interviewed. the http://energimerking.no 45 journal of sustainable architecture and civil engineering 2019/2/25 results project leader holds their role for four years, spanning the procurement process, the planning process and the erection of the buildings. from the contractor, the project leader was interviewed (3). in addition, a site tour was given and led by the building manager. documents from the competition period were analysed. these comprised the competition programme and the invitation to prequalification, which was issued to “wildcard” architects as part of the norwegian wildcard programme to encourage the growth of newly established architecture firms (wildcard, 2011). the interviews were based on a guideline developed in the nero project. the mapping of the procurement route shown in fig. 3 was, in the end, discussed with the project leader from sit and adjusted. the aim of the interviews was to answer the following main question: “what is the relationship between the objectives of the project, the use of clt, the procurement process, costs and the degree of innovation?” the questions asked to the interviewees were structured under four themes (procurement process, use of clt, innovation and cost) and they were: _ introduction _ what role did you have in the project? (owner, buyer, project developer, architect, contractor) _ what functional and technical requirements were defined for the building? _ does your company have a strategy document for environmental goals in procurement and implementation? _ the procurement process and implementation model _ can you describe the procurement route? _ what was the criteria for the tender competition? _ which contractual form was chosen? _ was there a kind of cooperation? _ use of clt _ why was clt chosen? _ did the parties have experience with the use of clt? _ will you use clt in future projects? _ innovation _ what was the level of innovation in the project? _ cost _ what was the cost in relation to the budget? _ what was the connection between procurement, contracts and costs? _ what are the expectations of the future impact on costs of an increased market share for clt? _ do trust, enthusiasm and coherent goals have a bearing on the quality and cost of the building? the main phases of the building process followed the timeframe below: 2012–2013: planning and design phase with architecture competition in the spring of 2013. 2013–2015: procurement and cooperation phase. 2015–2016: construction phase. the procurement route and the design phase step by step: 1. sit (the building owner) defined the limit and goals for energy use, co2 emissions and cost of the building. 2. an open prequalification competition (with negotiation) for wildcard architects was announced and four architect firms were chosen. journal of sustainable architecture and civil engineering 2019/2/25 46 3. sit arranged a workshop for the wildcard firms and 50 other attendants to get input to the architecture competition. 4. an architecture competition for the four firms was carried out. the winner was mdh architects, together with arne henriksen architects as the coaching firm and masu planning (from copenhagen) as landscape architects. the winning design was proposed with a steel and concrete structure and brick as cladding to integrate the new design with the existing buildings. 5. sit was then contacted by trebruk and itre, who encouraged the use of clt in the design instead of the proposed steel and concrete structure because of the lower ghg emissions of wood and its competitive cost. 6. a project team consisting of sit, mdh architects and consultants engaged by sit developed the pre-project for the tender announcement with a goal for 50% co2 reduction compared to a steel and concrete building in accordance with the norwegian building code of 2010. the energy performance should meet the passive house standard. 7. a prequalification phase was initiated, and four contractors were chosen. 8. the four contractors, with their consultants, mdh architects, and professionals from sit were trained by trebruk and itre on how to build with clt. they also visited clt projects in norway. 9. the contractor, veidekke as, won the competition for the prime contract with cooperation. 10. sit, mdh architects and veidekke, with their consultants, developed the project in cooperation to be a cost-effective project. 11. the board of sit approved the comprehensive contract with veidekke, and the building process could start. 12. the system for involving planning in engineering (ipp) was followed, during both the cooperation phase and the detailed design phase. 13. involving planning (ip) was carried out throughout the construction phase and the “porsche system” of construction (described later in the paper). 14. due to the use of clt instead of cast-in-place concrete, the construction phase was shortened by four months. environmental goals and architecture competition the goals for energy use, co2 emissions and construction cost were defined from the start. student apartments in norway should be built within a certain cost limit to achieve public grants from the norwegian public authorities. the owner (sit) had previous experience of the difficulties in keeping the total cost of the student housing below the initially defined limit, so the criteria for the tender announcement were therefore set to obtain the best building quality within the required cost limit. sit strategy aims for architectural qualities and environmental goals for student accommodation projects, including universal design, being good examples of high energy efficiency buildings (meeting passive house standard or higher energy performance), use of renewable energy and reduction of ghg emissions. sit therefore defined a template for the procurement process and construction process with defined demands for environmental goals. architecture competitions have often been used by sit because they are the best opportunity to obtain a high-quality architecture that provides a good environment for the students. specifically, for the moholt 50/50, an important goal was to achieve an innovative design with the best solutions for blending the new design in to the existing student residence complex. sit was encouraged to go for a wildcard competition. wildcard is a norwegian register for young architect firms founded in 2011. for the competition, the wildcard firm could bring along an experienced firm as a “coach47 journal of sustainable architecture and civil engineering 2019/2/25 ing firm”. an open prequalification competition was announced for firms in the norwegian wildcard register. criteria for the prequalification was based on understanding of the task, description of the team and how the team is put together, and relevant reference projects. four firms were chosen. they participated in a workshop together with sit, the municipality of trondheim, residents from the moholt student complex, neighbours, representatives from the universities and the norwegian state housing bank. the intention was for the participants to understand the user’s needs and to receive and give input for defining the criteria of the architecture competition before its official announcement. during this workshop, sit got to know the four architect firms and the firms became acquainted with sit’s vision and goals for the moholt 50/50. criteria for selecting the winning project were the architectural quality, social and environmental values and the capability to implement the proposed design. the four entries to the competition turned out to be very different and represented a wide range of solutions for the moholt area. this gave sit an overview of the feasibilities for the area and helped them to understand the best design strategy. the four entries were presented to a jury and to a fig. 2 site plans of the four competing entries (source: jury report 2013), the winning entry (upper-right) concentrated the building volume around the common area, the “allmenning”. the other entries had different levels of dispersed infill of the area journal of sustainable architecture and civil engineering 2019/2/25 48 committee from sit. the jury gave a report and suggested a winner. the sit committee evaluated the entries, the presentations from the competitors and the report from the jury and gave their recommendation to the sit board for decision. the winning team was mdh architects, with arne henriksen architects as the coaching firm and masu planning (from copenhagen) as landscape architects. the winning entry had steel and concrete as the load-bearing system and brick as cladding – in line with the existing part of the student residence area. the criteria for the architecture competition had no requirements regarding the use of specific structural systems for the design. the decision to use clt came at the end of the design competition, on suggestion from trebruk as as a “wood promoter” and itre as a clt adviser. this was in line with sit’s strategy for low ghg emissions. the board then agreed on assessing clt constructions for moholt 50/50. the board of sit visited clt producers and clt buildings in austria and clt buildings in norway, and listened to experts and experience from other builders. the board was, in the end, convinced that clt construction would be good for the users, good for the environment and that the costs would not be higher than construction in steel and concrete. tender announcement and contracts sit is not a public organisation, but is based on an “act of law” from 1948. rules for public procurement are to be followed only when public grants cover more than 50% of the total cost of a building project. for moholt 50/50, only 37% of the cost was covered by public grants. irrespective, the board of sit always recommend arranging a tender competition. four contractors were invited for prequalification for an invited tender announcement. the four contractors had little or no experience in building with clt. to prepare and motivate the contractors for the bid with clt, sit arranged a special course for them together with the architects, the consultants, the “wood promoters” and the clt producers. they also visited norwegian clt projects together. the pre-project, with its goals of clt usage and environment and quality performance, was then developed by sit, mdh architects and the consultants engaged by sit to define the tender competition. the contract form which was used was the “prime contract with cooperation”, during the planning phase and “prime contract” for the construction phase. the criteria for the tender competition were: _ 50% of crediting points were given to the final price (total tender cost, proportion for additional payment (mark-up payment), and cost per hour); and _ 50% of crediting points were given to the contractor’s qualifications and ability to cooperate (cv and references for key personnel, the implementation/execution model during the design and construction phase, references for buildings meeting passive house standard and the use of clt, and a system for follow-up during the guarantee period). the contractor veidekke won the competition. the cooperation phase lasted for about four months. during this time, the ipp method (involving planning and design) was used. during the cooperation period, cost-effective and smart solutions were developed. this resulted in an extension to the size of the projects from providing for 465 students up to 632 students. the towers were extended from eight to nine storeys. all parts of the design team worked together to develop the solutions that were the basis for the prime contract for the construction. sit, the architects, the consultants, the contractor and some of the material suppliers were involved. the foundation for the cost-effective solutions chosen were the cooperation between the building owner, the architect, the consulting engineers and the contractor. 49 journal of sustainable architecture and civil engineering 2019/2/25 the construction phase one of the criteria for the tender competition was the process to be used for implementing the design in the construction phase. the winning contractor uses the “porsche system”, which is used for planning and implementation based on processes in the car industry. according to the “porsche system”, the implementation plan is followed weekly and the time allocated to each activity is adjusted to match the plan. this ensures that all the activities at the building site follow the same plan. the construction time was 20 months and the involved parties (suppliers, the contractor, consultants, and so on) planned the construction phase together during the previous cooperation phase to optimise the work schedule. discussion mid-rise buildings of more than four storeys built with clt are quite a novelty in norway because norwegian contractors have very little experience with the use of clt. the contractor veidekke defined a company strategy that follows national goals for the reduction of ghg emissions. about 75% of all dwellings in norway are wooden detached houses or other kinds of small wood houses, but the current trend shows that building density in norwegian cities is increasing, with more mid-rise apartment buildings and fewer detached houses being built. this may result in a shift away from small wooden dwellings towards concrete apartment buildings. a more ghg-friendly development for the future might, however, be a development that moves towards apartment buildings with clt constructions. the advantages of building with clt, according to the interviewed stakeholders of the moholt 50/50 competition, are: _ the embodied ghg emissions from the material are lower; _ a good indoor climate is provided; _ the low density of the structural frame simplifies the foundation design; _ the construction time is faster with clt than with concrete; _ the working conditions on site are improved, with less dust, noise and better temperatures; and _ total costs, including the financial costs, are competitive compared with other solutions. the disadvantages are: _ the cost for clt elements is high; _ there is a lack of experience and knowledge among architects, consultants and contractors; and _ there is a lack of pre-accepted solutions for fire and noise protection. the experience from the moholt project shows that innovative solutions are developed both during the early design phase and during the cooperation phase before the contracting phase. clt was used for load-bearing constructions and for floors above the second floor. wood surfaces are exposed in the ceilings and in at least one wall in each student apartment. the corridors and the kitchen have exposed wood in the ceilings and the walls. the roof, stairs and lift shaft are also made of clt. the owner stated that the façade solution is the most innovative solution of the project; to avoid damage due to shrinkage of the wood construction, a “telescope façade of wood” was developed. the façade cladding is built like pine shells, overlapping each other. costs moholt 50/50 got financial grants from the public enterprise enova for building to meet the passive house standard, which requires better energy performance than the national building code. they also received grants from the public enterprise innovation norway for the development of the clt concept, for educating contractors and for fire safety testing. sit is satisfied with the experience of building moholt and is optimistic about the costs. the project leader at sit believes that journal of sustainable architecture and civil engineering 2019/2/25 50 the cost for clt buildings will be more competitive than concrete buildings once all actors in the building market have gained enough experience and knowledge. according to the project leader at the contractor veidekke, the cost for building with clt compared to steel and concrete varies greatly for different building types. apartment buildings, kindergartens and other buildings with relatively small rooms are easy to build with clt, while office buildings – with the need for large open areas and flexibility – are more challenging. clt elements are more expensive than concrete elements, but the financial costs are lower due to the shorter erection time for the building. the total cost for moholt 50/50 and for new clt apartment buildings are, therefore, promising. the contractor also stated that all parts in the project must invest resources to be winners in a new market. the contractor, however, has more focus on the environmental issues than on the costs and believes that demand for solutions with reduced ghg emissions will be a growth market. developing the project and building the design team the list above for the procurement route and design phase is, at first sight, long and complex. the complexity is due to the owner, sit, taking an active part in developing the project and in building a knowledgeable design team. a large part of the definition work is done in the early planning phase in cooperation between the owner, the architect, the contractor and the consultants. in fig. 3, the key stages of the procurement route are mapped to show the connections between all actions. trust between all parties is vital for a positive end result. the contractor stated that sit made a good foundation for trust throughout the whole process of planning and construction. when they gave the information about building with clt to the four competing prequalified contractors before the tender competition, a mutual understanding was established between the purchaser and the bidders. a common understanding is that the procurement process can be used to secure both the good team work in all stages, and a high-quality end product. fig. 3 mapping the procurement route, development of the project and building up of the design team the work presented in this paper aims to discover the type of relationship that exists between the design process, the procurement model and the final cost of clt buildings. the results show that the purchaser’s knowledge and experience, the environmental goal and the request for the use of wood in the tender announcement were decisive driving forces for conclusion 51 journal of sustainable architecture and civil engineering 2019/2/25 fig. 4 erection of a tower at moholt allmenning. the wood elements and prefabricated bathrooms are added floor by floor. photo: sit using clt for moholt allmenning. the results also show that the construction costs of clt buildings are competitive when compared to similar buildings built in concrete and steel. for nzebs, which are subject to restrictions on ghg emissions from materials production, the use of clt is, however, a better choice than the use of steel and concrete. it is crucial that the project owners have good knowledge of the qualities they want to achieve, and knowledge about how to ask for these qualities in the bid announcement. poor specification will give the contractors the opportunity to win the competition on low price but with a low-quality end product. good specification is therefore crucial for obtaining the desired qualities for the building. it is not easy to predict how costs may develop for clt buildings once more experience is achieved. more experience will, however, always result in increased efficiency. a growing demand for low-ghg solutions will most likely result in a demand from public building developers for clt buildings. this is what the market needs to achieve the experience necessary to develop competitive, cost-effective solutions. acknowledgement this work was financed thanks to the contribution of the eu horizon 2020 nero – nearly zero energy wooden buildings in nordic countries, grant agreement 754177. referencesbergesen j.d., suh s., baynes t.m., musango j.k., environmental and natural resource implications of sustainable urban infrastructure systems, environmental research letters, 12 (12) (2017). https://doi. org/10.1088/1748-9326/aa98ca betongelement foreningen, årsmelding 2017 (concrete elements ‘society, year book 2017) buchanan a., östman b., frangi a., fire resistance of timber structures, national institute of standards and technology, 2014. https://doi.org/10.6028/ nist.gcr.15-985 directive 2010/31/eu of the european parliament and of the council of 19 may 2010 on the energy performance og buildings (recast). fercovic j., gulati s., comparing household greenhouse gas emissions across canadian cities, regional science and urban economics, 60 (2016) 96–111. https://doi.org/10.1016/j.regsciurbeco.2016.06.010 göswein v., krones j., celentano g., fernández j.e., habert g., embodied ghgs in a fast-growing city: looking at the evolution of a dwelling stock using structural element breakdown and policy scenarios, journal of industrial ecology, 22 (6) (2018) 1339–1351. https://doi.org/10.1111/jiec.12700 hoeller c., mahn j., quirt d., schoenwald s., zeitler b., apparent sound insulation in cross-laminated timber buildings, in: nrc publications archive, national research council canada, 2017. https://doi. org/10.1121/1.4987243 malmqvist t., erlandson m., francart n., kellner j., minskad klimatpåverkan frpn flerbostadshus, stockholm 2018 norsk standard (2013) ns 3700:2013, kriterier for passivhus og lavenergibygninger – boligbygninger. oslo: standard norge. pagnoncelli l., morales f., cross-laminated timber system (clt): laboratory and in situ measurements of airborne and impact sound insulation, euroregio 2016, porto, portugal, european acoustic association. journal of sustainable architecture and civil engineering 2019/2/25 52 skaar c., solem b., rüther p., composite floors in urban buildings: options for a low carbon building design, 6th forum wood building nordic trondheim 17, trondheim norway, 2017. skullestad j.l., bohne r.a., lohne j., high-rise timber buildings as a climate change mitigation measure – a comparative lca of structural system alternatives, energy procedia, 96 (2016) 112–123. https://doi.org/10.1016/j.egypro.2016.09.112 structural timber association, fire safety in timber buildings, in: structural timber engineering bulletin 7, 2014. østnor t., faanes s., lædre o., laminated timber versus on-site cast concrete: a comparative study, in: proc. 26th annual conference of the international group for lean construction (iglc), gonzález, v.a. (ed.), chennai, india, (2018) 1302–1312. https://doi. org/10.24928/2018/0313 directive 2010/31/eu: https://eur-lex.europa.eu/legal-content/en/txt/?uri=celex%3a32010l0031, last accessed 07/02/19. tek17: www.dibk.no/byggereglene/byggteknisk-forskrift-tek17/, last accessed in 2019. moholt 50-50 trondheim: www.arkitektur.no/moholt-5050, last accessed in 2018. energimerking: www.energimerking.no/no, last accessed in 2018. treindusrtien: www.treindustrien.no, last accessed in 2018. nero wood for zero: www.neroproject.net, last accessed in 2018. mjøstårnet, moelven: www.moelven.com/mjostarnet, last accessed in 2018. wildcard: www.arkitektur.no/om-wildcardordningen, last accessed in 2019. about the authors anne gunnarshaug lien senior research scientist sintef building and infrastructure main research area energy efficiency in buildings and architecture address høgskoleringen 7b, 7465 trondheim, norway e-mail: anne.g.lien@sintef.no nicola lolli research scientist sintef building and infrastructure main research area energy efficiency in buildings address høgskoleringen 7b, 7465 trondheim, norway e-mail: nicola.lolli@sinte https://eur-lex.europa.eu/legal-content/en/txt/?uri=celex%3a32010l0031 https://eur-lex.europa.eu/legal-content/en/txt/?uri=celex%3a32010l0031 http://www.dibk.no/byggereglene/byggteknisk-forskrift-tek17/ http://www.dibk.no/byggereglene/byggteknisk-forskrift-tek17/ http://www.arkitektur.no/moholt-5050 http://www.arkitektur.no/moholt-5050 http://www.energimerking.no/no http://www.treindustrien.no http://www.neroproject.net http://www.moelven.com/mjostarnet/ http://www.moelven.com/mjostarnet/ http://www.arkitektur.no/om-wildcardordningen http://www.arkitektur.no/om-wildcardordningen mailto:nicola.lolli@sintef.no 47 darnioji architektūra ir statyba 2013. no. 3(4) journal of sustainable architecture and civil engineering issn 2029–9990 ultra-high performance concrete mixes with reduced portland cement content detlef heinz, tobias gerlicher, liudvikas urbonas* technische universität münchen, cbm centre for building materials, baumbachstr. 7, d-81245 münchen, germany *corresponding author: urbonas@tum.de http://dx.doi.org/10.5755/j01.sace.3.4.4569 ultra-high performance concrete (uhpc) usually contains a very high proportion of ordinary portland cement which requires a high amount of energy for its production. the present investigations aimed at systematically developing uhpc produced with supplementary cementitious materials to achieving strengths above 150 mpa at an age of 28 days under normal conditions or above 200 mpa with heat treatment. the cement was replaced with different amounts of ground granulated blast furnace slag and fly ash. the effect on the workability of fresh concrete and the evolution of compressive strength was investigated. a reduction in water and super plasticizer requirement was obtained with these materials. however, compressive strength decreases with the content of mineral additions. this loss could be partly compensated by increasing the fineness of the slag or fly ash. it was found that the type and dosage of superplasticizer have a significant effect on strength development. an appropriate choice of materials enabled the achievement of strengths above 200 mpa after heat treatment for concrete made with binders containing 25% portland cement and 75% slag. keywords: binder, fly ash, ggbs, mineral additions, uhpc. 1. introduction contemporary uhpc is produced with a high content of portland cement (dafstb 2008) whose production requires considerable amounts of energy. thus the development of new uhpc compositions with less portland cement clinker is of economical and ecological importance. in the present investigations, ground granulated blast-furnace slag and fly ash were used as alternative cementitious materials to replace portland cement in the reference mix m2q. as well as comparable workability, strengths similar to the reference mix were required. new mix compositions were designed based on the knowledge of the hydration of m2q, the reactivity of the new components and the packing density of the particles in the mix as whole. 2. methods the packing density of the mixes was determined according to schwanda (schwanda 1966). the fresh concrete was characterized by measuring slump flow with the haegermann cone according to en 1015-3, but without jolting. the relative yield stress and viscosity were measured using a rotation viscometer to provide a better description of fresh concrete workability. the relative yield stress was determined using the herschelbulkley model and the relative viscosity with the bingham model, see (metzger 2006). the specimens were demoulded after 24 hours and either stored in water at 20°c until testing or heat treated for 24 hours at 90°c (age one to three days) and then stored at 20°c/65% rh. the heat treated specimens were investigated before and after heat treatment, i.e. at an age of 3 days, and then at ages of 7, 28, 56, 90 days and 2 years. the specimens stored in water at 20°c were investigated at the same ages as the heat treated specimens. the composition of the young concrete was investigated in situ seven minutes after water addition and up to the time of setting using x-ray diffraction. a position sensitive detector was used with cu ka radiation. a scintillation detector was used for the analysis of powder prepared from the hardened concrete specimens, (gerlicher et al. 2009). the silicate phases were investigated using 29si-nmr spectroscopy. this combined approach enabled the quantification of the amounts of crystalline and amorphous silicate phases. 3. reference concrete composition the m2q (maximum grain size 0.5 mm) mix was used as the initial reference composition (tab. 1). the phase composition of specimens stored in water at 20°c and heat treated at 90°c determined by x-ray diffraction and nmr spectroscopy are shown in fig. 1. in the case of the specimens stored in water, it is apparent 48 that the amount of c-s-h increases with age because of the reaction of silica fume with portlandite. after 28 days the reaction was still incomplete, cf. fig. 2. table 1. reference concrete composition constituents m2q cement kg/m³ 876 silica fume kg/m³ 142 water kg/m³ 187 superlasticizer kg/m³ 13 quartz flour kg/m³ 218 quartz sand kg/m³ 985 m2q 0 10 20 30 40 50 60 0 7 14 21 28 age [days] s i c on te nt [m ol % ] cem cem_ht sf sf_ht csh csh_ht quarz fig. 1. silicate phases in m2q determined by nmr spectroscopy. after water storage at 20°c and before and after heat treatment at 90°c (ht) heat treatment accelerated the reaction of the silica fume to c-s-h which was to a large extent complete after 7 days. in contrast to the specimens stored in water, the cement did not react appreciably following heat treatment (age 3 days). at an age of 28 days about 80% of the cement was still present as unreacted clinker in the concrete. the amount of c-s-h was observed to increase in the heat treated concretes by 18% between 28 days and 2 years. because of the pozzolanic reaction of the silica fume, an increase of 67% was determined for the specimens stored in water at 20°c. thus without heat treatment more c-s-h formed over two years resulting in a degree of hydration of the silica fume similar to that of the heat treated concrete. after two years more cement had reacted in the concrete which had not been heat treated, fig. 2. the measurements did not reveal a reaction of the quartz components. 4. use of ground granulated blast-furnace slag (ggbs) ground granulated blast-furnace slags of different fineness were used to replace portland cement in the reference mix m2q at 15, 35, 55 and a maximum of 75 vol.%. the effect of superplasticizer type and dosage on the workability of the fresh concrete and the compressive strength of the hardened concrete was investigated. at first, the cement was replaced by ggbs similar in fineness to the cement (< 40µm). since the lower surface area of ggbs requires less wetting than cement and the reaction of ggbs is slower, slump flow increased considerably with the amount of ggbs at constant water content of the mix. consequently, the water content was reduced to obtain workability comparable to the reference m2q, i.e. a slump flow of approximately 25 cm. this resulted in a reduction of water/binder ratio. increasing amounts of ggbs also led to lower compressive strengths. in the case of the concrete with 15% replacement, the 28 d compressive strength was 188 mpa, similar to the strength of the reference concrete stored in water. with heat treatment, the strengths were near the reference concrete. heat treatment enabled strengths above 200 mpa for cement replacement up to 55%, see (gerlicher et al. 2008). the investigations on the phase composition of fresh concrete up to first setting with in situ x-ray diffraction showed, as expected, a decrease in the amount of clinker phases and the formation of ettringite and portlandite. no change in the amount of quartz flour was apparent. the amount of portlandite decreased with ggbs content, (gerlicher et al. 2009). even after prolonging the measurement to 84 hours, no portlandite was present in the mix with 75% replacement. fig. 2. unreacted silicate phases after storage in water at 20°c and heat treatment at 90°c (ht) at ages of 28 days (left) and 2 years (right). ggbs-35 and ggbs-75 concretes with 35 vol.% and 75 vol.% replacement of cement by ggbs, respectively. ht: heat treated concrete 49 in investigations on concrete with ggbs, nmr spectroscopy revealed higher degrees of hydration of portland cement at high ggbs contents. a reduction in the degree of hydration of silica fume due to the production of less portlandite was also observed (fig. 2). it is apparent that heat treatment resulted in a premature standstill of the ggbs reaction. like the reference mix m2q, heat treatment caused a rapid reaction of the silica fume in concrete with 35 vol.% replacement of cement by ggbs (ggbs-35). no further reaction was detectable after 7 days. without heat treatment, the silica fume continued reacting, almost reaching the strength of the heat treated concretes after 2 years. both cement and ggbs in heat treated concretes only reached a low degree of hydration which barely changed in the following 2 years (fig. 2). like the reference mix m2q, more c-s-h was formed after two years if heat treatment was not applied. the amount of c-s-h in the heat treated concrete increased by about 11% between 28 days and 2 years. an increase of as much as 80% owing to the reaction of the silica fume was observed during the same time period for the concrete stored in water at 20°c. even after two years, no appreciable silica fume reaction was observed for the concrete with 75% replacement by ggbs (ggbs-75) and not subjected to heat treatment. although heat treatment accelerated the pozzolanic reaction, only 20% of the ggbs reacted, see fig. 2. a fine ggbs (< 10 µm) was used in further investigations. the increased fineness affected the workability and strength of the concretes. lower slump flow and higher compressive strengths were measured (gerlicher et al. 2008). the ability of superplasticizers based on polycarboxylate ether to liquefy the mixes was investigated. it was found that superplasticizer dosage and type have a significant effect on strength development. it was possible to reduce the dosage considerably from 4.2 (sp1) to 1.5 wt.% (sp2) with respect to cement weight. the low dosage had a decisive effect on the strength development of the concretes. with a suitable choice of materials, it was therefore possible to achieve strengths over 200 mpa after heat treatment with only 25% cement and 75% ggbs similar in fineness to the cement (fig. 3). 0 50 100 150 200 250 300 m2q-sp1 m2q-sp2 ggbs-75sp1 ggbs-75sp2 c om pr es si ve s tre ng th [m p a] 7d 28d 7d-ht 28d-ht fig. 3. comparison of the effectiveness of superplasticizers sp1 and sp2 for concrete adjusted to the same workability and with the same water content with respect to the binder, i.e. sum of cement and ggbs. ht: heat treated concretes 5. use of fly ash the effect of fly ash as a pozzolanic binder component on the workability of the fresh concrete and the compressive strength of the hardened concrete was investigated. the differently reactive constituents of the reference mix were partly or completely replaced by fly ashes of different fineness. it was shown in (heinz et al. 2009) that the replacement of cement by fly ash reduces the requirement on water and superplasticizer of the mix. however, compressive strength is lower at higher replacement levels. this loss of strength can be partly compensated by increasing the fineness of the fly ash. if fly ash is substituted for quartz flour, the fineness of the fly ash determines the workability of the fresh concrete. independent of fly ash fineness, the strength of the reference mix with quartz flour was achieved. based on the results obtained on the substitution of individual mix components in (heinz et al. 2009), different levels of combined replacement were considered by taking packing density and the chemical reactivity of the components into account. the two mixes m1f and m2f in tab. 2 were designed (gerlicher et al. 2009a). table 2. composition of mixes m2q, m1f, m2f composition m2q m1f m2f cement kg/m³ 876 747 572 fly ash kg/m³ 0 244 487 silica fume kg/m³ 142 121 144 water kg/m³ 187 187 187 superplast. kg/m³ 13 13 13 quartz flour kg/m³ 218 0 0 quartz sand kg/m³ 985 1039 871 in the following, two 4-component systems comprising cement, fly ash of medium fineness, silica fume and quartz are considered. the systems are characterized by a reduced proportion of the energy-intensive materials cement and quartz flour. the optimized mixes m1f and m2f exhibited the same workability properties as the initial mix m2q. however, the mix m2f rapidly stiffened after initial good workability (fig. 4). strength decreases with increasing fly ash content and simultaneous cement reduction (fig. 5). the compressive strength of the heat treated concretes was well over 200 mpa. owing to the high cost and scarcity of silica fume, the replacement of this material is of economic interest. the partial and complete replacement by processed fly ash (< 10 µm) had been investigated (heinz et al. 2009). as well as differing chemically from silica fume, this material is finer possessing a higher specific surface. starting from the reference mix m2q, 25, 50 and 100 vol.% of the silica fume was replaced by processed fly ash in mixes sa25, sa50 and sa100, respectively. the resulting enhanced water requirement of the fly ash concretes had a pronounced effect on fresh concrete consistency. 50 despite smaller particle surface areas for wetting, the lower packing density of the particles worsened workability. to be able start mixing the concrete with complete replacement at all, it was necessary to raise the superplasticizer dosage by 39%. this concrete was then, however, high viscous. 0 1 2 3 4 5 6 7 8 9 10 m2q m1f m2f r el at iv e vi sc os ity [n m m m in ] 0 5 10 15 20 25 30 r el at iv e yi el d st re ss [n m m ] relative viscosity relative yield stress fig. 4. relative yield stress and viscosity of the mix m2q and the optimized mixes m1f and m2f 0 50 100 150 200 250 300 m2q m1f m2f c om pr es si ve s tre ng th [m p a] 7d 28d 7d-ht 28d-ht fig. 5. compressive strength of m2q and the optimized mixes m1f and m2f. ht: heat treated concrete owing to the slow hydration reaction of fly ash, the strength development of the concretes stored in water at 20°c became slower with decreasing silica fume content. thus the 28 day strength decreased with the fly ash content of the mix. in the case of the heat treated concretes, the strength of the reference mix can be reached for replacement up to 50 %. the strength of the concrete completely without silica fume (sa100) was lower, but still well above 200 mpa. it should be taken into account that mix sa100 was produced with a higher superplasticizer dosage which delays strength development, see fig. 6. 0 50 100 150 200 250 300 m2q sa25 sa50 sa100 c om pr es si ve s tre ng th [m p a] 7d 28d 7d-ht 28d-ht fig. 6. compressive strength in dependence of proportion of silica fume replaced by sifted fly ash, ht: heat treated concrete 6. conclusions owing to the energy intensive production of portland cement clinker and its high content in state-of-the art ultra high performance concrete (uhpc), the present research focuses on the reduction of the portland cement content of uhpc while maintaining good workability and 28 day compressive strengths above 200 mpa after heat treatment at 90°c for 24 hours. investigations on the effect of binder composition on workability, the hydration process and strength development showed that this could be achieved by the use of ground granulated blast-furnace slag (ggbs) und fly ash as a binder component. the replacement of portland cement by ggbs or fly ash is shown to reduce the requirement of the mix on water and superplasticizer. however, compressive strength also decreases with replacement level. this can be largely compensated by increasing the fineness of the ggbs and fly ash. although the reduction in portland cement content in concretes made with ggbs enhanced the degree of hydration of the cement, the degree of hydration of the silica fume was lowered because less portlandite was available for the pozzolanic reaction. apparently, the reaction of the ggbs came to a standstill after heat treatment. investigations with different types of superplasticizer showed that superplasticizer dosage and type have a significant effect on strength development. with a suitable choice of materials strengths above 200 mpa were achieved with only 25% portland cement and 75% ggbs after heat treatment. good fresh concrete workability and high strengths were obtained for separate replacement of cement or quartz flour by fly ashes of different quality. a combined replacement of cement and quartz flour also proved favourable for fresh and hardened concrete properties. exchanging silica fume for processed fly ash led to coarsening of the mix as a whole and, as expected, deterioration of workability. the production of concrete with complete replacement of the silica fume by fly ash was 51 only possible with an increased superplasticizer dosage. it is possible to reach the strength of the reference mix for replacement levels up to 50%. even the strength of concrete without silica fume was still above 200 mpa. acknowledgment the investigations were performed in the project “binder optimization” within the priority programme spp 1182 funded by the german research foundation (dfg) on sustainable construction with uhpc. the authors thank the dfg for funding this project. references dafstb-sachstandsbericht 2008. „ultrahochfester beton“ heft 561, deutscher ausschuss für stahlbeton, beuth-verlag, berlin. gerlicher, t., heinz, d., and urbonas l. 2008. effect of finely ground blast furnace slag on the properties of fresh and hardened uhpc. in: proceedings of the second international symposium on uhpc, universität kassel, pp. 367–374. gerlicher, t., hilbig, h., and heinz, d. 2009. einfluss des hüttensandmehleinsatzes auf den hydratationsverlauf von ultrahochfestem beton. in: proceedings of the 17th internationale conference on building materials (ibausil), weimar, pp. 02-0596 – 02-0598. gerlicher, t., leonhardt, s., heinz, d., and urbonas, l. 2009. einfluss des steinkohlen-flugascheeinsatzes auf die frisch und festbetoneigenschaften von ultrahochfestem beton, in: proceedings of the 17th internationale conference on building materials (ibausil), weimar , pp. 01–1091 – 01–1098. heinz, d., and gerlicher, t. 2009. eigenschaften ultrahochfester betone mit zementklinkerarmen bindemittelsystemen. im rahmen des dfg spp 1182 nachhaltiges bauen mit ultrahochfestem beton (uhpc) / technische universität münchen.. – zwischenbericht. mezger, t.-g. 2006. das rheologie handbuch, 2. auflage, vincentz network, hannover. schwanda, f. 1966. das rechnerische verfahren zur bestimmung des hohlraumes und zementleimanspruches von zuschlägen und seine bedeutung für den spannbetonbau. in: zement und beton, v. 37, pp. 8–17. received 2013 06 11 accepted after revision 2013 07 23 detlef heinz – prof. dr., head of chair of mineral engineering at technische universität münchen, cbm centre for building materials. main research area: recycling of secondary raw materials in construction materials, cement – development and application, concrete additions, durability of mineral building materials, ultra high performance concrete. address: technische universität münchen, cbm centre for building materials, baumbachstr. 7, d-81245 münchen, germany. tel.: +49 89 28927056 e-mail: heinz@tum.de tobias gerlicher – phd sudent at technische universität münchen, centre for building materials. main research area: ultra high performance concrete. e-mail: tobias.gerlicher@web.de liudvikas urbonas – dr., head of working group binders and concrete additions at technische universität münchen, cbm centre for building materials. main research area: cement chemistry, binders with gypsum, durability of mineral building materials, ultra high performance concrete. address: technische universität münchen, cbm centre for building materials, baumbachstr. 7, d-81245 münchen, germany. tel.: +49 89 28927056 e-mail: urbonas@tum.de 17 darnioji architektūra ir statyba 2013. no. 1(2) journal of sustainable architecture and civil engineering issn 2029–9990 challenges and dimensions of sustainability in social housing: general consideration and the case of kaunas indrė gražulevičiūtė-vileniškė*, jūratė kamičaitytė-virbašienė, artūras narvydas kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania * corresponding author: indre.grazuleviciute@ktu.lt http://dx.doi.org/10.5755/j01.sace.1.2.2873 the article is aimed to discuss and reconsider the concept and challenges of the social housing in the world and in lithuania. the research consists of three major parts. in the first part the evolution of social housing from the 18th century until nowadays was analyzed and evaluated and the main trends of architectural expression of social housing were distinguished and shortly characterized. the second part was devoted to the introduction of the dimension of sustainability in the design of affordable housing. the idea of sustainable architecture and the trends of its expression were presented and the composite trends of social housing in urban settings with dimensions of sustainability were formulated and characterized. the third part of the research dealt with the local specifics of the city of kaunas: the possibilities of localization of the social housing of different trends were analyzed and the experimental design of the social housing complex demonstrating the possibilities of application of environmentally friendly technologies and the potential of rehabilitation of neglected urban areas was shortly presented. keywords: social housing, sustainable architecture, kaunas, lithuania. 1. introduction relevance of the research. the term “social housing” can be interpreted differentially in various political and institutional contexts; generally this term refers to the rental housing units, owned and managed by the state or nonprofit institutions or by public-private partnerships aimed at providing accommodation that is affordable to eligible households whose needs are not met by the market (dght, 2012; hhc, 2012; sf, 2012). this research was induced by the lack of the social housing in lithuania and particularly in kaunas and the challenges of creating the environmentally sustainable social housing in urban settings. however, the deeper analysis of the issue revealed the more global perspective, contradictions and ambiguities related with the social housing and the issue of sustainability in this context: 1) the basic challenge underlying the idea of social housing is how to create the adequate living conditions with minimal possible economic costs. the extreme results of this challenge can be either the very high quality housing that is as equally expensive to construct and to rent as commercial development or low cost but poor quality development that soon degrades into slums; 2) the economic constraints are not the only challenge in the social housing sector. subsidized housing is a subject of strong ethical and social sensitivity. the issues of social stigmatization and social segregation should be dealt with extreme precaution in the social housing area. the social paradox of the subsidized housing is that even if the planning and design is done with the extreme precaution and devotedness of architects and institutions involved the results can be shockingly unexpected. take the new gourna village designed by h. fathy, which had all the features of environmentally friendly, socially responsible and economically feasible design, but still ended as a failure (steele, 1989); 3) the third complex challenge – the socioeconomic, sociocultural, and environmental responsibility – was added to this contradictory puzzle with the increasing environmental awareness and the rise of the concept of sustainability. it can be predicted that with the continuous growth of the world’s population, which had recently reached seven billion, the demand for the affordable housing and the pressure on the environment by the construction industry will increase in the future. the showcase of this process will be the developing countries in asia, africa, and latin america, which simultaneously have to cope with the unauthorized urban growth. the populations in the majority of the postcommunist transition countries are shrinking. nevertheless, these countries still face the problem of affordable housing. high percentage of urban poor or those social groups, who cannot afford any form of private housing or high rents, are present in countries like ukraine, latvia, and lithuania. in the year 2004 lithuanian residents who could not afford to 18 purchase or rent their own housing were demanding 8500 social housing units. currently this demand is circa 26 000 housing units. some applicants are doomed to wait for the social housing even for 20 years. circa 3 billion litas are needed in order to meet this demand and this makes the social housing one of the most costly areas of social care. the social housing units constitute only three percent of the total housing stock in lithuania (las…, 2010; sf…, 2012). the situation in transition countries can be referred as the soviet paradox: the majority of the housing stock, except the higher quality apartments for the communist party officials, of this period was designed and constructed as economy class flats. the poor quality of works and materials is evident in many cases as well. some skeptics note that the housing stock of the soviet period, which, in fact constitutes the majority of urban fabric of transitional countries, can degrade into slums and urban ghettoes, if no measures will be taken (tung 2000; milerius et al. 2009). the issues discussed above justify the relevance of this research, which is aimed to review the history and trends of social housing and to propose the classification of the social housing models, to analyze the possibility to introduce the dimension of sustainability into the design and construction of the social housing, and to formulate the proposals for development of social housing in kaunas. 2. methods in order to understand the general and local aspects of social housing and the dimension of sustainability in designing and constructing the affordable housing units, the complex methodology of the research was formulated. the research includes: the analysis of literature in order to determine the stages of development and challenges of social housing; the analysis of projects and examples in order to determine the trends of social housing; comparison and generalization in order to distinguish and characterize general models of social housing; analysis on site in the city of kaunas and the analysis of maps and aerial photographs in order to explore the dimension of contextuality and to find the possible congruencies between the type and design of the social housing and the qualities of the surrounding environment; experimental design by a. narvydas in order to demonstrate the possibilities of architectural expression, sustainable design and possible links with the context of the project of the subsidized housing; generalization and formulation of the conclusions. 3. results 3.1. development and trends of social housing analysis of literature has demonstrated that the development of the social housing is closely related with the industrial revolution and its outcomes. the two extremes of the mere necessity of workforce and the effectiveness on the one hand and the utopian thought on the other had defined the landscape of what nowadays could be seen as the predecessors of the social housing during the 18th and 19th centuries. the early examples of the worker housing provided by the state or factory owners are the housing for the salt-works workers in the arc-et-senans designed by n. ledoux and the housing constructed for the industrial workers in the british factories of industrial revolution in the 19th century (samalavičius 2008). however, throughout the 19th century the problem of providing at least the decent housing for the population of growing cities remained unsolved and, in fact, had aggravated in some aspects. the notorious dumbbell tenements in new york city were the example of the misery of the urban poor. house and garden magazine of that period wrote: “the dumbbell block is perhaps the worst type of tenement ever allowed in a modern, enlightened community. the halls and ten of the fourteen rooms on each floor are dark and ill-ventilated, dependent for light and air solely upon narrow airshafts which give little or no light below the top floors” (adnc 2012). harsh social criticisms, for example the j. riis’s investigative journalism “how the other half lives” and the increasing understanding of the human needs and rising living standards had caused the breakthrough in social housing development in pre-war, inter-war and post-war 20th century (tung 2001). this point in history marked the clear understanding of difference between the cheap commercial housing and the social housing: the first category was profit oriented and the owners did not care about the living conditions as far as the profits kept flowing and the authorities imposed no requirements and penalties; meanwhile, the social housing was aimed to improve the existing human misery caused by the cheep tenements and unauthorized housing. literature demonstrates that the structure, architectural expression, location and links with context of social housing are closely linked with the development of the styles and trends of the modern and contemporary architecture throughout the 20th and 21st centuries (table 1). the first worth mentioning examples corresponding to the concept of social housing were the so called “idealistic” or showcase examples. these housing units for workers, the prominent examples of which were constructed in germany and austria, were the great social success, as running water and sanitary facilities were not common feature of worker housing at that time. the classic example of this stage is the karl marx-hoff by karl ehn in vienna with service facilities, abundant parkland (only 18.5 percent of the 1000 m long and 156 000 m² large area was built up in this housing estate, with the rest of the area developed into play areas and gardens) and expressive high quality architecture was the actual glorification of the working class and the “ring-road of the proletariat” (tung 2001, vd 2012, kmh 2012). strong social commitment of the early 20th century architectural avant-garde was manifested in the ideas of the proponents of industrially prefabricated affordable housing and expressed in the condensed manner in the iconic quote by le corbusier (1985) published in 1923: “a great epoch has begun. there exists a new spirit. industry, overwhelming us like a flood which rolls on towards its destined ends, has furnished us with new tools adapted to this new epoch. the equilibrium of society today depends on it. architecture has for its first duty, in this period of renewal, that of bringing about a revision of values, a revision of the constituent elements of the house. <…> industry on the grand scale must occupy itself with building and establish the elements of the house on a mass-production basis. we must create the mass-production spirit. the spirit of constructing mass19 production houses. the spirit of living in mass production houses. the spirit of conceiving mass-production houses.” the törten housing estate built in 1926–1928 in dessau is the example of this functionalist mass-production attitude towards the affordable living space (te 2012). the törten estate was made famous and saved by the names and fame of w. gropius and bauhaus; however, there are numerous less successful examples like the universally known and the most quoted notorious pruitt-igoe case, which well embodied the gap between the good intentions of functionalist design and inhumane environments it can create. another affordable housing concept form the modernist era can be referred to as the large housing units concept. these are the large vertical housing units with integrated service facilities, roof gardens, and “the streets in the sky”, i.e. the deck access scheme, constructed in the following decades after the world war ii. the brutalism style, taking its name from the french expression for the architectural concrete – béton brut and declaring the honest use of construction materials, was predominant during that time. le corbusier’s unité d’habitation is considered the prototype and the iconic example of this architectural trend. even if the realizations of the housing units concept can be traced back to the communal houses of the pre-war soviet russia (including the most widely known narkomfin building), the post-war brutalism architects, such as alison and peter smithsons, jack lynn and ivor smith had created the most characteristic examples like robin hood gardens in london and park hill in sheffield (melvin 2008). table 1. trends and models of social housing of the 20th and 21st centuries trend of social housing historical period and region of formation and development basic idea and features chrestomatic examples of architectural expression pr ew ar p er io d idealistic, showcase model interwar period, mainly in western europe blocks with relatively small flats with basic amenities, showcase modernist architecture, abundant green spaces, service facilities including laundries, kindergartens, doctor office etc. großsiedlung britz hufeisensiedlung (“horseshoe estate”), bruno taut, martin wagner, 1925–1930, berlin karl marx-hof, karl ehn, 1927–1930, vienna torten housing estate, walter gropius, 1926, dessau siemensstadt housing estate, hans scharoun, martin wagner, walter gropius, otto, bartning, fred forbat, hugo haring, paul rudolf henning, 1929–1934, berlin. po st w ar p er io d functionalist concept from interwar period up to now, in developed and developing countries housing units of different size constructed of standardized prefabricated building parts pruitt-igoe housing scheme, minoru yamasaki, 1954, st. louis, missouri functionalist approach to the housing problem in the soviet union and socialist countries from 1950s until the collapse of the soviet regimes multi-flat, multi-storey housing units constructed of standardized prefabricated building parts mass housing projects implemented in the soviet union and socialist countries large housing units concept from post-war period up to now, in developed and developing countries large housing units with communal facilities unité d’habitation, le corbusier, 1947–1952, marseille park hill, jack lynn and ivor smith, 1957–1961, sheffield pedregulho housing, affonso eduardo reidy, 1950–1952, rio de janeiro regionalist concept from the second half of the 20th century up to now, in developed and developing countries interpretation and application of local building traditions, techniques and materials dareeya housing, hasan fathy, 1975, dariyah, saudi arabia new gourna village, hasan fathy, 1945–1948, new gourna, egypt structuralist concept from the second half of the 20th century up to now, the united states, europe and other developed countries architecture facilitating and fostering social relations, housing complexes composed of repetitive structural units habitat 67, moshe safdie, 1967, montreal, canada. mountain dwellings, bigbjarke ingels group, 2008, copenhagen postmodernist or individualist concept from the second half of the 20th century up to now, the united states, europe and other developed countries individual approach to each case, unique expressive designs, community involvement extra vert housing, hamonic + masson, 2011, paris ecological concept from the second half of the 20th century up to now, in developed and developing countries minimizing energy consumption, introduction of green technologies and vegetation block 103, stern, 1980’s, berlin bedzed, bill dunster, 2000–2002, hackbridge, london realistic concept or “slum upgrading” second half of the 20th century, in developing countries in asia, africa, latin america legalizing and upgrading of infrastructure and buildings in existing (often illegal) settlements slum networking, from 1987, india 20 the sixties and seventies were marked by the shifts in the architectural thought and diverse criticisms from architectural and social points of view of the modernist concepts of affordable housing. jane jacobs (1961) criticized the entire idea of modernist urban planning based on the free plan and strict functional zoning, seeing the multifunctionality as the main driver of the healthy and lively cities. the good example of such criticism is her ideas on the deck access scheme preferred by the brutalism architects: “not only are these interior parts of the buildings streets in the sense that they serve the comings and goings of residents, most of who may not know each other or recognize, necessarily, who is a resident and who is not. they are streets also in the sense of being accessible to the public. they have been designed in an imitation of upperclass standards for apartment living without upper-class cash for doormen and elevator men. anyone at all can go into these buildings, unquestioned, and use the traveling street of the elevator and the sidewalks that are the corridors. these interior streets, although completely accessible to public use, are closed to public view and they thus lack the checks and inhibitions exerted by eye-policed city streets.” o. newman’s research (1973) on the modernist housing estates and crime also contributed to this area. his study of new york has demonstrated the higher crime rate in highrise blocks of flats with abundance of open space around than in more densely built low-rise housing projects. the main newman’s conclusion was that the failure of these estates could be conclusively linked to the modernistic architecture and urban design (utdps, 2012). the strong opponent of functionalism ch. jencks (1987) thus described the detonation of the notorious pruitt-igoe housing scheme at 3.32 pm on 15 july 1972: “pruitt-igoe was constructed according to the most progressive ideals of ciam (the congress of international modern architects) and it had won an award from the american institute of architects when it was designed in 1951. it consisted of elegant slab blocks fourteen storeys high with rational “streets in the air” (which were safe from cars, but as it turned out, not safe from crime); “sun, space, and greenery”, which corbusier had called the “three essential joys of urbanism” (instead of conventional streets, gardens, and semi-private space, which he banished). it had a separation of pedestrian and vehicular traffic, the provision of play space, and local amenities such as laundries, crèches, and gossip centres all rational substitutes for traditional patterns. moreover, its purist style, its clean, salubrious hospital metaphor, was meant to instil, by good example, corresponding virtues in the inhabitants. good form was to lead to good content, or at least good conduct; the intelligent planning of abstract space was to promote healthy behavior.” t. turner (2008) thus has described the philosophical and ideological climate of the sixties and seventies: “since then, the pessimists have been able to gather much evidence for their view that human society is incapable of progress: stalin’s great terror, the second world war, the holocaust, the atomic bomb, the vietnam war, the 300 lesser wars between 1945 and 1990, the industrialization of agriculture, environmental degradation and destruction of the world’s primeval forests. it is no wonder that so many academic disciplines talk of “postmodernism””. discontent with design limitations and rules imposed by modernism finally resulted in the shift towards what is often called the postmodernism in architectural design and planning. according to t. turner (2008), in architecture, postmodernism means anything that comes after the modern movement. the main identified shortcomings of the modern movement in architecture were its internationalism, universalism and functional minimalism (jencks, 1987; welsch, 2004). thus, it is not surprising, that multidimensionality, multivalency, complexity, individualism, pluralism, traditionalism, and symbolism were identified as the solutions for these problems (welsch, 2004; turner, 2008). according to t. turner (2008), “instead of trying to create a rationalist utopia, with a place for everything and everything in its place, postmodern planners have embraced the concept of diversity”. the same trend of course is applied to the social housing. the idea of diversity means, that local traditions, craftsmanship, details and features could be integrated in the design and the local populations could have their say. this approach is embodied in the works of h. fathy. as he noted in his work “architecture for the poor”, “in nature, no two men are alike. even if they are twins and physically identical, they will differ in their dreams. the architecture of the house emerges from the dream; this is why in villages built by their inhabitants we will find no two houses identical. this variety grew naturally as men designed and built their many thousands of dwellings through the millennia. but when the architect is faced with the job of designing a thousand houses at one time, rather than dream for the thousand whom he must shelter, he designs one house and puts three zeros to its right, denying creativity to himself and humanity to man. as if he was a portraitist with a thousand commissions and painted only one picture and made nine hundred and ninety nine photocopies. but the architect has at his command the prosaic stuff of dreams. he can consider the family size, the wealth, the social status, the profession, the climate, and at last, the hopes and aspirations of those he shall house. as he cannot hold a thousand individuals in his mind at one time, let him begin with the comprehensible, with a handful of people or a natural group of families which will bring the design within his power. once he is dealing with a manageable group of say twenty or thirty families, then the desired variety will naturally and logically follow in the housing.” the multivalency of the postmodern design allows to search for individual solutions for each individual case of social housing and to take into account not only the light, space, greenery and functionality, as the modernists did, but also local traditions, ecological precautions, esthetic and psychological aspects. even if the design and construction of affordable housing is still restricted by the limited costs, the original idea or expressive design can save the project. this is the postmodernist paradox in a positive sense: the social housing project can become an urban landmark and icon. looking back at the history of architecture in general and of social housing in particular, it is possible to conclude, that both modernist and postmodernist concepts have their 21 own advantages and shortcomings. the analysis of the strengths and weaknesses of above distinguished trends of social housing (table 2) helps further constructing the argument on the prospects of the social housing with diverse architectural expression and the strong dimension of sustainability. 3.2. introduction of sustainability concept into social housing the last decades of the 20th century can be characterized by the re-estimation of values in virtually all areas (turner, 2008). these ideas had crystallized into the concept and strategies of sustainable development. sustainable development stands for meeting the needs of present generations without jeopardizing the ability of future generations to meet their own needs; the issue of sustainability can be analyzed in four overlapping dimensions, i.e. social, cultural, economic, and environmental and is applied to virtually all aspects of life (benson and roe, 2000; jdsd, 2002; ec, 2012). in its strategy for sustainable development the european union declares (reussd, 2009; ec, 2012) the goals to “achieve a continuous long-term improvement of quality of life through the creation of sustainable communities able to manage and use resources efficiently, able to tap the ecological and social innovation potential of the economy and in the end able to ensure prosperity, environmental protection and social cohesion.” the european union key priority challenges of sustainability are: climate change and clean energy, sustainable transport, sustainable consumption and production, conservation and management of natural resources, public health, social inclusion, demography and migration, global poverty and sustainable development challenges (reussd, 2009; ec, 2012). regarding these shifts in understanding of sociocultural and socioeconomic development and ecology, it is not surprising that the field of architectural design seriously takes into account these obligations to the environment, the present and future generations. the sector of social housing is extremely important and sensitive in this regard. in order to analyze the dimension of sustainability in the design of the social housing it is necessary to define and characterize the concept of sustainable architecture. the review of literature shows the proliferation of terms used to describe the designs based on some principles of sustainability: “sustainable architecture”, “environmentally responsible architecture”, “green architecture”, “ecological architecture”, “eco-architecture”. even if the first post-war attempts to design with nature not against it can be dated to sixties and seventies, there is still confusion in defining and characterizing this architectural trend. the term “sustainability” is in use for more than 20 years now, though the internet search engines do not provide the satisfactory straightforward definition of sustainable architecture. in our pervious researches (kamičaitytė-virbašienė and gražulevičiūtė-vileniškė 2010, 2011) we defined the sustainable architecture as the architecture entirely based on the principles of sustainable development. the sustainability table 2. strengths and weakness of the main trends of social housing trend of social housing strengths weaknesses idealistic, showcase model high quality architecture and public spaces high costs. show case models often remain only the positive examples, but are not introduced on the wider scale functionalist concept low costs, use of prefabricated elements and possibility of mass-production uniformity, functional minimalism, often associated with dreariness and boredom by the society, low selfidentification with architecture and environment large housing units large housing blocks include various services and amenities. large scale buildings can become prominent architectural examples like le corbusier’s unité d’habitation and pedregulho housing by affonso eduardo reidy safety problems in stairwells and other inner spaces of communal use, sense of isolation of community, the aesthetics of béton brut and other ideas of brutalism are often rejected by the society and communities as dull and inhumane regionalist concept respect for and use of local traditions and materials resulting in low costs and in architectural aesthetics acceptable to society and communities, respect for traditional lifestyles, continuity and evolution of architectural traditions strengthening of social segregation as wealthier social classes may appreciate modern construction techniques and materials and trendy cosmopolitan architectural aesthetics structuralist concept respect for social interactions, distinctive architecture structuralist designs may not always produce the desirable effect of social condenser postmodernist or individualist concept search for individual solutions for individual problems, diversity, inventiveness, unusual solutions, attractive designs acceptable to society postmodernist architectural experiments can result in kitsch ecological concept use of renewable and recyclable resources, respect for environment, promotion of biodiversity and environmentally friendly lifestyles extreme care for ecology may result in a secondary treatment of social issues. some of environmentally friendly technologies are expensive and require special maintenance realistic concept or “slum upgrading” low costs, preservation of local communities improvements may not eliminate social segregation, stigmatization, and safety problems 22 of the building should be programmed in the stage of design and be present throughout the entire cycle of the existence of the building: form the design and preparation of the construction site to the demolition or reuse of the building or conversion of the site. the sustainable architecture not only should embody the principles of sustainability itself; it also should enhance the sustainable development of the environment: to promote the rational use of energy and resources, social cohesion, preservation of historic and natural environment, and contribute to the improvement of general quality of life. several trends of sustainable architecture can be distinguished based on the research by j. wines (2000). the table 3 shows the trends of sustainable architecture and their characteristic contextual environment. different documents, organizations, and designers provide different ideas and guidelines on how to design sustainable buildings. these ideas can be expressed in abstract principles, such as contextuality and legibility, social and ecological responsibility, psychological and aesthetic acceptability, durability and flexibility (kamičaitytėvirbašienė and gražulevičiūtė-vileniškė 2010, 2011) or in very concrete guidelines, such as (wines, 2000): smaller buildings, use of recycled and renewable materials, use of lowembodied-energy materials, use of harvested lumber, water catchment systems, low maintenance, recycling of buildings, preservation of the natural environment, energy efficiency, solar orientation, access to public transportation. table 4 demonstrates the possibilities of design of social housing with the dimension of sustainability. below we discuss diverse ways how the four basic dimensions of sustainability can be integrated into the design of the affordable housing. social sustainability. social inclusion and cohesion, social diversity are the important aspects of sustainability regarding social housing. this can be achieved by urban infill thus creating social mix, by compact multifunctional development with public spaces, and by involvement of community and future residents. the applicants for the social housing can be very diverse: those, who want but cannot substantially improve their living conditions because of various reasons and those, who do not want to put any effort and take the social care for granted. the involvement of the applicants in the design and even construction of social housing could be a good means for social cohesion and inclusion and help distinguishing between these two groups. c. cumberlidge and l. musgrave (2007) present numerous examples of involvement of socially vulnerable groups into design and construction projects. luis blanc apartment building in paris is a good example of a social housing unit built as an urban infill in the historic environment (falkenberg 2008). cultural sustainability. high quality aesthetics, psychological acceptability, identification with the living environment, contextuality, cultural continuity and evolution are important for sustainable social housing designs. cultural continuity and evolution can be maintained through the regionalist designs, involvement of local materials and craftsmanship. involvement of artist into social projects and creating unique expressive designs are good ways to create a cultural phenomenon out of a social housing. expressive exteriors should be favored even if they are kind of fasadisms, hiding traditional flats. scattered-site public housing project in charleston in the united states started table 3. trends of sustainable architecture (wines, 2000; kamičaitytė-virbašienė and gražulevičiūtė-vileniškė, 2010, 2011) trend short description characteristic environment (hu – historic urban center and historic suburbs; iu – inner urban areas; pu – suburban and periurban areas; rl – rural landscape; nl – natural landscape) characteristic functions and scale (ac – architectural complexes; lpc – large scale public and commercial buildings; mpcr – medium scale public, commercial, residential buildings; si – small scale buildings, mainly individual houses) aesthetization of eco-technologies aesthetics created by ecological technologies and environmentally friendly innovations hu, iu, pu, rl, nl ac, lpc, mpcr, si building-garden concept integration of the garden into building iu, pu mpcr, si building-landscape concept integration of architecture into landscape rl, nl ac, lpc interpretation of natural forms architecture takes inspiration from the forms of nature and cosmology; characteristic organic shapes pu, rl, nl mpcr, si adaptation of traditional building forms and techniques adaptation of vernacular building traditions and materials, interpretation of ethnic architectural forms pu, rl, nl mpcr, si coherence of sustainable architecture and built historic urban environment visual continuity, evolution of and adding new values to historic urban environment hu ac, mpcr, si 23 table 4. composite trends of social housing in urban settings with dimensions of sustainability social housing trend introduction of dimension of sustainability into social housing trends abbreviation realization possibilities functionalist concept introduction and aesthetization of eco-technologies building-garden concept sustainable functionalism sf introduction of low cost eco-technologies roof terraces with gardens urban gardening large housing units concept introduction and aesthetization of eco-technologies building-garden concept sustainable housing complexes shc introduction of low cost eco-technologies roof terraces with gardens regionalist concept adaptation of traditional building forms and techniques introduction of eco-technologies sustainable regionalism sr construction from wood or mud brick, buildings strongly adapted to local climatic conditions involvement of the residents into design and construction activities urban gardening structuralist concept introduction and aesthetization of eco-technologies sustainable structuralism ss introduction of low cost eco-technologies roof terraces with gardens urban gardening postmodernist or individualist concept introduction and aesthetization of eco-technologies building-garden concept interpretation of natural forms coherence of sustainable architecture and built historic urban environment environmentally friendly postmodernism efp solutions, strongly related to context, involvement of future residents into building design, involvement of artists, individual, expressive, unexpected and even ironic designs ecological concept introduction and aesthetization of eco-technologies building-garden concept interpretation of natural forms coherence of sustainable architecture and built historic urban environment ecological sustainability ecols adaptation of existing housing stock urban infill adaptive re-use of non-residential buildings reuse of building materials, such as shipping containers use of renewable and recyclable materials urban gardening realistic concept introduction of eco-technologies adaptation of traditional building forms and techniques coherence of sustainable architecture and built historic urban environment economic sustainability econs adaptation of existing housing stock urban infill upgrading of existing residential buildings reuse of building materials involvement of the residents into design and construction activities urban gardening in the late 1980s adopted the form of traditional charleston single house, thus not only contributing to the solution of the social problems but also to the continuity and extension of the city’s architectural culture (tung 2001). the row houses initiative in houston demonstrated the possibility to involve artists and community into socially sensitive project (cumberlidge and musgrave 2007). mountain dwellings designed by bjarke ingels group in copenhagen are a good example of non-traditional individual approach to housing and of remarkable design (ad 2012). economic sustainability. energy efficiency, sustainable consumption and production are equally important for economic and environmental sustainability. even if achieving high energy efficiency or constructing a passive social housing require more costs, this would allow to spend from 3 to 5 times less on maintenance (sf 2012). the affordable housing projects aimed at improving the quality of life of the poor can require some contribution – financial or in a form of work – by its intended beneficiaries. social housing and slum upgrading projects (slum networking in india) in developing countries demonstrate the social and economic benefits of this approach. for example, the elemental project in chile provides housing as a baseline service for individuals to adapt and extend as their social and economic conditions change (cumberlidge and musgrave 2007). environmental sustainability. climate change, sustainable energy and transport, preservation and sustainable management of natural resources are important ecological aspects that can be addressed in the social housing projects. the use of local and renewable resources, technological improvements, application of ecological technologies can become an integral part of the social housing design. the use of shipping containers in the temporary housing projects currently is trendy and environmentally sustainable practice (sch 2011). the ivory park ecocity project in johannesburg in south africa has demonstrated that the application of ecological technologies in solving social problems is not a prerogative of developed countries (cumberlidge and musgrave 2007). 24 3.3. challenges of social housing in kaunas current situation of social housing in kaunas. kaunas, the second largest city in lithuania with its current population of 321 200 inhabitants (kms 2012), has to deal with similar social housing problems as the other urban settlements of the country. the municipality of kaunas currently has more than 3000 applications for social housing. several strategies were considered for solving this problem: purchasing or renting flats in the existing apartment blocks, building new social housing units. real estate developers propose the municipality to purchase or to rent newly built apartments in commercial development housing projects, considering such private-public partnership as the fast and the most appropriate solution for the problem. the idea of subsidized renting is difficult to implement due to the peculiarities of the real-estate market in lithuania, where the official market for rent is nearly inexistent. thus current situation of the social housing in the city demonstrates that neither strategy has adequately solved the problem yet (sf, 2012). possible types and locations of social housing in kaunas. the shifts of the economic situation and the consequent shifts of the real estate prices in this decade have demonstrated that the social housing sector needs diverse and flexible solutions not limited to business-as-usual functionalist designs. the affordable housing solution can range from the realistic concept of upgrading and adapting of the existing buildings to the ecological and postmodernist concepts, aimed at changing the negative image of the subsidized housing. the realistic (econs) and ecological (ecols) social housing concepts can be beneficial in the periods of economic downturns, when vacant properties that have low demand in the real estate market can be purchased or rented by the municipality and adapted to the social housing needs. the postmodernist or individualist (efp), structuralist (ss), regionalist (sr) and even large housing units (shc) social housing concepts can be implemented with the purpose of raising the prestige of the social housing, as currently it is often viewed as a sign of lower social status or even social stigma. municipality often has to deal with the protests of communities when renting or purchasing the flats for the social housing use (sf, 2012). the expressive architecture of the social housing units and the public spaces created around them could foster urban renewal in a wider scale. the map in the fig. 1. demonstrates the possible contextual links between the trends of sustainable social housing identified in the previous section and the areas of kaunas city of different character. the map was designed after considering not only environmental aspects, but also the urban morphology, functions, heritage values, and local identities of different areas in kaunas city. the postmodernist or individualist (efp), ecological (ecols) and realistic (econs) social housing concepts can be used in historic center and suburbs and territories of former fortress. in the territories of valuable relics of rural landscape priority should be given to the ecological (ecols) and postmodernist or individualist (efp) concepts. in the territories of lowrise residential housing and public and commercial objects (mostly the peripheral parts of the city) the functionalist (sf), regionalist (sr), postmodernist or individualist (efp) concepts should be chosen as the trends for social housing, though ecological (ecols) and realistic (econs) concepts are also possible. in the territories of high-rise residential housing and public and commercial objects (modernist residential districts) the functionalist (sf), structuralist (ss) and even large housing units (shc) concepts can be chosen as the main trends for social housing, though ecological (ecols) concept is also possible. in the territories of industrial and commercial objects the most appropriate trends can be functionalist (sf), brutalist (shc) and structuralist (ss) concepts of social housing. functionalist (sf), structuralist (ss) and postmodernist or individualist (efp) concepts can be the most suitable in the areas of commercial, public and residential objects (for ex.: urban corridors, territorial neighborhoods centers). outcomes of the experimental design of sustainable social housing in kaunas. the results of the experimental design by a. narvydas illustrate the concept of postmodernist or individualist social housing (efp), aimed at changing the image of such development and demonstrating the possibility of sustainable urban regeneration induced by the social housing project. highly devastated plot was chosen near the garrison camp in panemune residential area at the eastern part of kaunas city. the main idea of this project was to implement the concept of the “city within a city”, consisting of 14 autonomous, but also jointly connected buildings. each building was carried out for commercial, recreational, and residential functions. commercial and residential functions are separated by the first-floor terrace, which could be used as possible place for maintaining private gardens. the height of the buildings is 4 floors plus roof terrace because contextual building type is low-rise single-family housing; other architectural features such as buildings location, forms, sizes, scales, colors also highly correspond with the contextual environment. the whole complex consists of 168 social apartments, creating a total 26,880 m² of residential and commercial spaces. the conceptual formation of adjacent areas is also proposed: the areas for further residential and commercial development, green spaces and links, riverfront and recreational infrastructure are designated (fig. 2). the energy supply for the whole complex would be provided from the sustainable systems such as: solar panels, wind turbines and geothermal energy. in order to provide solar energy solar panels would be installed on the roof of each building (it would cover 5376 m², providing 20 percent of required energy). another 10 percent would be provided by the wind power. it is proposed to install 19 turbines in the adjacent park area. the remaining energy (about 70 percent) would be obtained by geothermal energy; vertical collectors would be installed at the basement of each building. 25 fig. 1. hypothetical zones of social housing with dimensions of sustainability fig. 2. the conceptual formation of adjacent areas and proposed spatial pattern of the social housing quarter in panemune fig.3. the experimental design solutions of social housing quarter in panemune representing the postmodernist or individualist concept (efp) the use of ecological building materials is proposed in the experimental design: flat laminated wood panel façade is chosen, it consists of a steel frame (made from recycled materials), insulation, and pressed wood decorative panels. it was proposed to green the roof terrace as well: part of the roof terraces will be planted with native plant species: woody shrubs and herbaceous plants. system of rain water collection will be equipped: rain water accumulated on the roof will be filtered and collected in a tank in the basement; from there it will be used for watering plants in the roof terrace. the main result of the project – concentrated living and working spaces, created new attraction point at highly abandoned site of kaunas city by implementing principles of sustainable housing design. the main dimensions of sustainability implemented in this project are: the introduction of eco-technologies and building-garden concept, multi-functionality and fostering of social relations, improvement of environmental quality of adjacent areas, and coherence of sustainable architecture and built historic urban environment (the chosen building type, so-called morphotype, highly corresponds with panemune urban structure and spatial pattern) (fig. 3). 4. conclusions 1. the history and evolution of the social housing projects beginning with the start of the 20 th century demonstrate the relevance of this issue both in modernist and postmodernist architectural movements and strongly confirm and expand the social dimension in architecture present from the times of vitruvius. 2. the experience of the 20 th century and the failure of many functionalist affordable housing projects demonstrate that there is no universal model for social housing. on the other hand, experience demonstrates that even theoretically the most culturally and socially sensitive projects sometimes are doomed to failure. this shows the complexity and contradictions of socially orientated architecture in constantly changing economic and environmental conditions and proves that the individual problem needs individual solution. 3. in order to understand better the diversity of the models for social housing and the possibilities to modify and combine them for the better outcome, we had distinguished eight trends of architectural expression and organization of social housing idealistic showcase model, functionalist concept, large housing units concept, regionalist concept, structuralist concept, postmodernist or individualist concept, ecological concept, realistic concept or “slum upgrading” and demonstrated the possibilities to integrate the dimension of sustainability in this field. 4. the site and context of the social housing project are not less important than its type and design. the analysis demonstrates that from the one hand the social housing high-rise housing commercial obj. green spaces riverfront infrastructure fig. 2. the conceptual formation of adjacent areas and proposed spatial pattern of the social housing quarter in panemune the use of ecological building materials is proposed in the experimental design: flat laminated wood panel façade is chosen, it consists of a steel frame (made from recycled materials), insulation, and pressed wood decorative panels. it was proposed to green the roof terrace as well: part of the roof terraces will be planted with native plant species: woody shrubs and herbaceous plants. system of rain water collection will be equipped: rain water accumulated on the roof will be filtered and collected in a tank in the basement; from there it will be used for watering plants in the roof terrace. the main result of the project – concentrated living and working spaces, created new attraction point at highly abandoned site of kaunas city by implementing principles of sustainable housing design. the main dimensions of sustainability implemented in this project are: the introduction of eco-technologies and buildinggarden concept, multi-functionality and fostering of social relations, improvement of environmental quality of adjacent areas, and coherence of sustainable architecture and built historic urban environment (the chosen building type, socalled morphotype, highly corresponds with panemune urban structure and spatial pattern) (fig. 3). 26 fig. 3. the experimental design solutions of social housing quarter in panemune representing the postmodernist or individualist concept (efp) 4. conclusions 1. the history and evolution of the social housing projects beginning with the start of the 20th century demonstrate the relevance of this issue both in modernist and postmodernist architectural movements and strongly confirm and expand the social dimension in architecture present from the times of vitruvius. 2. the experience of the 20th century and the failure of many functionalist affordable housing projects demonstrate that there is no universal model for social housing. on the other hand, experience demonstrates that even theoretically the most culturally and socially sensitive projects sometimes are doomed to failure. this shows the complexity and contradictions of socially orientated architecture in constantly changing economic and environmental conditions and proves that the individual problem needs individual solution. 3. in order to understand better the diversity of the models for social housing and the possibilities to modify and combine them for the better outcome, we had distinguished eight trends of architectural expression and organization of social housing – idealistic showcase model, functionalist concept, large housing units concept, regionalist concept, structuralist concept, postmodernist or individualist concept, ecological concept, realistic concept or “slum upgrading” – and demonstrated the possibilities to integrate the dimension of sustainability in this field. 4. the site and context of the social housing project are not less important than its type and design. the analysis demonstrates that from the one hand the social housing projects should be “better located within the network of opportunities in cities” as the c. cumberlidge and l. musgrave (2007) note in order to avoid social segregation, the formation of ghettoes and the nonsustainable urban expansion. from the other hand, new projects can become catalysts for revitalization of deprived urban areas. our analysis of possible locations of different trends of sustainable social housing in the territory of kaunas demonstrates the importance of the coherence between the context and the trend of architecture. 5. the results of experimental design of sustainable social housing in kaunas by a. narvydas show possible individual solution for the particular place. the abandoned plot surrounded by single-family housing and objects of cultural heritage in the garrison camp in panemune is transformed into a quarter of social housing. proposed architectural expression and urban form of the quarter is consistent with the contextual architectural urban and natural environment using the principle of nuance (new development corresponds with the context according the location, size, scale, from, and colors of houses). 6. the use eco-technologies in the experimental social housing project is proposed: solar panels, wind turbines, geothermal energy, to use ecological building materials, to collect rain water, and to green roof terrace. 7. the designed quarter will be multi-functional complex, which will additionally create jobs and will foster social relations of inhabitants of the quarter. the qualitative changes of adjacent neglected areas are also planned: conversion of car parking garages into green recreational space – community park, the areas for further residential and commercial development, riverfront and recreational infrastructure are designated. thus the proposals of the project even exceed the limits of postmodernist social housing concept by creating a sense of community and catalyzing positive qualitative changes of abandoned adjacent areas. references the architecture and development of new york city. living together. tenements (adnc). 2012 columbia university. available at: http://ci.columbia.edu/0240s/0243_2/0243_2_ s1_2_text.html (accessed 17 may 2012). arch daily. 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available at: http://www.viennadirect.com/sights/marx.php (accessed 18 may 2012). received 2012 11 15 accepted after revision 2013 02 01 indrė gražulevičiūtė-vileniškė – associated professor at kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management. main research areas: valuation and preservation of cultural heritage, management of rural-urban interface, sustainable architecture. address: kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. tel.: +370 37 451546 e-mail: indre.grazuleviciute@ktu.lt 28 jūratė kamičaitytė-virbašienė – associated professor at kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management. main research areas: landscape visual quality analysis, evaluation and regulation by means of environmental design, methods of planned activity or object visual impact assessment, analysis of social preferences evaluating landscape visual quality and use of the analysis results in territory planning, sustainable architecture. address: kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. tel.: +370 37 451546 e-mail: jurate.kamicaityte@ktu.lt artūras narvydas – bachelor and master studies at kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management. main research area: sustainable architecture, social housing. address: kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. tel.: +370 672 91269 e-mail: archiz@mail.com 3 darnioji architektūra ir statyba 2013. no. 4(5) journal of sustainable architecture and civil engineering issn 2029–9990 relevance and extent of ecological architecture indrė gražulevičiūtė-vileniškė* kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania *indre.grazuleviciute@ktu.lt http://dx.doi.org/10.5755/j01.sace.4.5.5664 1. introduction the definition of ecology itself and the homocentric nature of architectural design, urban planning, and landscape architecture (thompson 2007) show us that sustainable design cannot be limited with site reclamation and renaturalization or seeking just to minimize or eliminate the harm to the environment without considering cultural, aesthetic, psychological, social, economic and other issues. today we observe the trend of merging the concept of ecology with the human sphere. actually, the ideas of differently merging the ecological concepts with human life had emerged with the start of the 20th century. take for example urban ecology, cultural ecology or ecoaesthetics. the nowadays widespread concept of sustainability encompasses multiplicity of fields and dimensions and allows us analyzing in its frame not only the issues of ecology, but also of social, cultural, and economic sustainability in the areas of architecture, urbanism, landscape architecture, territorial planning, heritage preservation etc. 2. conference “ecological architecture” in order to provide the possibilities for dissemination, discussions, and questioning of these sustainability ideas in different spheres and searching for the links between them, scientific and popular events of various levels are welcome. international scientific conference “ecological architecture”, which is organized by the department of architecture and land management of kaunas university of technology, is one of the first periodically organized scientific conferences in lithuania providing the forum for discussions of the applications of principles of sustainability and ecological ideas in the fields of architecture, urbanism, landscape architecture and other areas concerning management and formation of environment. as the concept of sustainability, at least in theory, becomes the dominating paradigm of development of societies and environment and the ideas of ecological lifestyles and environmental preservation become widespread. the aim of the conference – to link aesthetic, psychological, local identity and technological aspects of sustainable and ecological design in different areas – is undoubtedly relevant for lithuanian and regional development of research and studies. the conference “ecological architecture” has a prehistory, which also illustrates the gradual entrenchment of the ideas of sustainability in the discussions and research of architecture and related areas. the department of architecture and land management starting from the year 1995, when the studies of architecture where reestablished in kaunas university of technology, organizes scientific thematic conferences aimed at discussing relevant questions of architecture, urbanism, and land management. during the last conferences the relevance of the application of the principles of sustainability became evident: in 2007 the conference was held under the title “developing and developed landscape” and was aimed at discussing the interdisciplinary aspects of landscape development; in 2008 the conference was entitled “problems of horizontal and vertical urban development” and was devoted to the problematic of compact cities and urban sprawl; in 2009 the conference was organized under the title “ideas of sustainability in architecture and territorial planning”. starting from the year 2011, this conference, periodically organized by the department, gained the permanent title of “ecological architecture” reflecting the contemporary trends and the status of the international conference. the researchers from france, latvia, poland, and scientists and practitioners architects from lithuanian science and study institutions participated in the first conference “ecological architecture” held in 2011. starting from the year 2011, the conference is held every second year in rotation with international scientific conference “advanced construction” organized by the faculty of civil engineering and architecture of kaunas university of technology. in order to get closer to general public and professional community, this year conference “ecological architecture” was organized as a part of kaunas architecture festival, which took place in the city of kaunas in september and october. the festival was dedicated to waterfronts: historic cities and their links with rivers. thus “ecological architecture” in 2013 was also dedicated to city center revitalization, city and . editors word 4 water, landscapes and water. other topics of presentations, including the application of the principles of sustainability and ecological design to architecture, planning, and construction, critical approach to principles of sustainability and ideas of ecological design, influence of sustainable and ecological design on expression and development of contemporary architecture, digital design for sustainability etc., were also welcomed. the researchers from poland, greece, estonia and lithuanian science and studies institutions had participated in the conference including the invited speakers prof. friedrich kuhlmann and jekaterina balicka from estonian university of life sciences, prof. andrzej tokajuk from bialystok university of technology, and prof. anna januchta-szostak from poznan university of technology. comparing with the previous conferences organized by the department including the “ecological architecture” of 2011, it can be noted that the array and the understanding of the topics have expanded from the green roofs and straw bale houses to the flood management and sustainable urban drainage systems, cityscape and identity, sustainability and globalization, critique of the idea of ecological architecture, cultural heritage and sustainability, sustainable rural-urban interface. the website of the conference with the conference program, the book of abstracts, some photographs and general information can be accessed using the following link: http://ktu.lt/saf/turinys/international-conferenceecological-architecture. 3. review of articles the present issue of the journal of sustainable architecture and civil engineering mainly publishes the articles further elaborating the topics discussed during the conference “ecological architecture”: heritage preservation and sustainability, sustainability and globalization, city and water, sustainable rural-urban interface. 3.1. heritage preservation. sustainability has strong temporal and intergenerational dimensions that are underlined in its definition (throsby, 2002). evaldas ramanauskas and liucijus dringelis in their article “the inheritance of the soviet period: should it be evaluated?” discuss the soviet experience in landscape formation and settlement planning and the need for its present evaluation. they note that some features of urban and rural settlements, designed during the soviet period, today could be attributed to sustainable urbanism: systematic approach, integrity, assessment of natural conditions, sensitivity towards community needs, attention towards public spaces, and, especially, green areas. the authors maintain that the legacy and experience of the soviet era should not be wasted. they also note that “…in order to save the country’s residential construction experience, as well as maintain the historic urban diversity, it is important to evaluate planning and design work of the residential areas, which was carried out during the 50-year period.” this is especially relevant today, when we see the tendency to forget the soviet era researchers, planners, their accomplishments and to see the documents accumulated in archives as mere curiosity, considering these works irrelevant for the present day, because they were implemented under different ideological and economic system. the theme of the urban legacy of the past and its present day preservation and use issues is continued in the article by katarzyna hodor and julia klimek entitled “attempts and methods for revitalizing the centers of small localities. selected examples”. the article deals with renovation, revitalization, and management of small urban settlements in poland and presents two different examples the village stary paczków nearby opole rich in cultural resources and small town zabierzów in southern poland nearby krakow under pressure for rapid change and development – which allow authors to showcase different methods of analysis and management proposals aimed at preserving local identity and heritage and at the same time improving the quality of life for inhabitants. the article underlines the importance of such actions: “…the risk associated with the loss of individual landscape features of small towns may be irreversible and may lead to the loss of tangible and intangible landscape values.” in the practices of landscape architecture, architecture, and urban design it is crucial to understand that the concept of “empty space” does not exist and we always have some kind of natural and cultural context (stauskas 2009). domenico chizzoniti, letizia cattani, and luca preis in the article entitled “the memorial museum of jewish culture in prague. an example of urban regeneration” present the methodology and the alternative proposals for the intervention in the historic urban fabric of prague. the box-like modernist design proposals in the historic fabric could be discussed; however, two useful principles can be undoubtedly drawn from this research: the thorough analysis, good knowledge and appropriate interpretation of local history; the design principle of elaborating different alternatives that afterwards could be reconsidered and may point to their synthesis or to radically new design proposals. 3.2. sustainability and globalization. local identity is crucial to social, cultural, and even economic sustainability. the question of identity faces new threats and new development trends under globalizing forces. giedrė gudzinevičiūtė-vilkelė and evaldas ramanauskas in their article entitled “the impact of the specific elements of globalization on the spatial structure of lithuanian towns and their valuation” analyze the problem of consumer culture and its architectural manifestations in the townscapes of small settlements in lithuania. they underline the negative impact of uniform functionalist architecture of large shopping centers, compare them with standard housing schemes of the soviet period, which today pose many problems in the countries of the former soviet bloc. they propose the way of compromise: the uniform logos of commercial institutions would represent the recognizable globalizing trend but the adaptive re-use of the existing buildings should be favoured instead of new construction. 3.3. city and water. one of the major focuses of the conference this year was city and water. several articles dedicated to large and small scale water management projects and experience are presented in this issue of the 5 journal. their topics range from the influence of water on city’s identity to concrete examples and design proposals. in the article “the role of the river in the city centre and its identity” justina mačiukėnaitė and ingrida povilaitienė focus on lithuania and on the role of the rivers in the historical development and present identity of the cities, although they touch some european examples in order to show that the enhancement of the water in the cityscape and the maintenance of local identity can be achieved both by large scale interventions (as in the case of arhus) or just changing the attitude towards the river (as in the case of the urban “beach” in paris). according to j. stuart-murray (2007) in landscape architecture “more recently, perhaps because of the growing incidence of unpredictable weather patterns, which have led to increased frequencies of flooding, concerns have turned to the management of man-made hydrology. most sustainable urban design and landscape architecture is now typified by articulations of best practice in sustainable urban drainage systems.” the research by anna januchta-szostak presented in the article “multifunctional riverside buffer parks – the research on nature-urban revitalisation of river valleys” is the example of several trends of contemporary sustainable landscape architecture and environmental management: revitalization of urban river spaces, flood management, riverside buffer parks. the comprehensive study presents the evaluation of riverside revitalization projects with the system of criteria, the methodology for creation of riverside buffer parks, and the application of the research outcomes and guidelines in the design of park in poznan. niki manou-andreadis and maria milona in the article “water designing for sustainability, purity and comfort” discuss the historical and architectural-urban relevance of water in human living environment and underline water’s significance in development of tourism facilities. the authors present five realized examples of their small-scale water designs in recreation institutions in greece, discuss their environmental, psychological, aesthetic, social benefits and the links with historic tradition. 3.4. rural-urban interface. simona basilico, patricio eduardo enriquez, massimiliano bevacqua, and fabio villa touch a very important issue of rural-urban interconnections in their article “agricultural land into the city: 5 environmentally sustainable ecological parks”. as an opposition of the urbanization of the countryside they propose some naturalization and “ruralization” of the abandoned and faceless urban areas in the city of vigevano (italy), which, after proposed interventions, would have not only ecological, but also social recreational and educational benefits. the mentioned above articles confirm the attitude maintained by the conference “ecological architecture” that sustainability in architecture and related fields can be approached from many different points of view and, simultaneously, the common, integrating points can be traced. it is possible to conclude with the words of niki manou-andreadis and maria milona that “in a holistic view, sustainable architecture could be an interconnected network of natural and social systems that provides a diverse range of environmental, cultural and economic benefits.” references stauskas v. 2009. kai kurie šiuolaikinės architektūros aspektai [some aspects of contemporary architecture]. urbanistika ir architektūra, 5(33), 270–278. stuart-murray j. 2007. the practice of sustainable landscape architecture. in: benson j. f., roe m. landscape and sustainablity. abingdon, taylor & francis, 222–235. thompson i. 2007. the ethics of sustainability. in: benson j. f., roe m. landscape and sustainablity. abingdon, taylor & francis, 16–35. throsby d. 2002. economics and culture. cambridge, cambridge university press. indrė gražulevičiūtė-vileniškė – associated professor at kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management. main research areas: valuation and preservation of cultural heritage, management of rural-urban interface, sustainable architecture. address: kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. tel.: +370 37 451546 e-mail: indre.grazuleviciute@ktu.lt 5 journal of sustainable architecture and civil engineering 2021/2/29 *corresponding author: rongrong.yu@uon.edu.au comparing architects’ perceptions of the usefulness of digital design environments with their aspirations for sustainable design in australia received 2021/01/22 accepted after revision 2021/06/18 journal of sustainable architecture and civil engineering vol. 2 / no. 29 / 2021 pp. 5-20 doi 10.5755/j01.sace.29.2.28355 comparing architects’ perceptions of the usefulness of digital design environments with their aspirations for sustainable design in australia jsace 2/29 http://dx.doi.org/10.5755/j01.sace.29.2.28355 rongrong yu* school of engineering and built environment, griffith university, gold coast, australia michael j. ostwald unsw built environment, university of new south wales, sydney, australia introduction this paper uses a combined method – survey and semi-structured interviews – to evaluate the perceived effectiveness of digital design environments for supporting architects’ sustainable design practices. in most contemporary firms, architects’ sustainable design aspirations are reliant on the use digital design tools and associated computational platforms. past research, however, suggests that a level of uncertainty exists about whether these tools and platforms are sufficient for this purpose. to investigate this issue in an australian context, architects were invited to take part in an online survey to identify general trends and perceptions, leading to a series of semi-structured interviews, to analyse the issues in detail. the survey results (n = 70) suggest that despite considering sustainable design an important objective in their design practice, participants believe that digital design tools require further development and improvement. detailed interviews (n = 15) then identified specific factors affecting the usefulness of digital design tools. these results enhance our understanding of australian architects’ experiences using digital design tools. it also contributes to improving the tools that support sustainable design practices throughout the architectural, engineering and construction industry. keywords: sustainable design practice, sustainable design digital tools, architectural design practice. the united nations’ (2015) sustainable development goals (sdgs) articulate the critical importance of sustainable design in the architectural, engineering and construction (aec) industry. buildings and construction generate 36% of global energy use and 39% of energy-related carbon dioxide (co2) emissions (abergel et al., 2017). these emissions have increased in recent years, reaching 10 gtco2 in 2019, the highest level on record (iea, 2020). sustainable design for the built environment seeks to reduce the ecological footprints of national and regional economies. in australia, sustainable design principles are embedded in the graduate competencies and professional education of architects. they are also intrinsic to the australian national construction code (ncc 2019) and to the state environment planning policies (sepps) which govern building design. as such, like many other countries in the world, sustainable design practices are vitally important across australia’s aec sector. journal of sustainable architecture and civil engineering 2021/2/29 6 some of the most important mechanisms used to support aec professionals to design in a sustainable way are software tools and platforms, which are collectively called “digital design environments” (ddes). aec professionals use ddes to model environmental and socioeconomic issues when developing and constructing building designs (akadiri et al., 2012). ddes support architects and engineers to incorporate large volumes of contextual data – from energy, daylighting and hydraulics to planning codes, embodied energy and supply chain efficiency – into the performance analysis and optimization of design alternatives. architects use ddes to supplement their knowledge and experience with computational decision support systems that can provide real-time feedback during the optimisation and analysis processes (coorey & jupp, 2014). past research examining ddes and sustainable design has traditionally focused on technical capacity and accuracy (peters, 2010). for example, research has identified dde’s low levels of user-friendliness and integration with cad software (weytjens & verbeeck, 2010), lack of capacity for life cycle assessment (naboni, 2014), and problems associated with early design phases, excessive data-input, poor component libraries (weytjens & verbeeck, 2010). such ineffective aspects of ddes in relation to sustainable design processes, may result in architects avoiding ddes completely, or using them selectively and inexpertly during the design process, potentially leading to suboptimal performance of buildings. such past research into ddes has shaped their technical development, but technology adoption, acceptance and application decisions are as much a reflection of user experiences and organisational aspirations, as of actual dde capacity to support sustainable design practice (liu et al., 2018; sepasgozar & davis, 2018). it is these last two factors – concerning designers’ views about the effectiveness of ddes and their aspirations for producing sustainable design – that are the catalysts for this paper. furthermore, past research has shown that these perceptual and aspirational factors vary in different countries and in response to diverse industry contexts. australian examples and research are well represented in technical research into ddes, but there are fewer examples which consider perceptions and aspirations, and none which consider both. thus, this paper addresses a research gap associated with the perceived effectiveness of digital design environments for supporting australian architects’ sustainable design goals. to address this knowledge gap, this paper explores the overlap between two related research questions. 1. what are architects’ attitudes to, and experiences of, using ddes to design sustainable buildings? 2. how is sustainable design considered within architectural practice? rather than using these two questions to frame distinct and separate answers, this paper looks at the overlap between them, which provides an indication of where challenges and opportunities exist in architectural practice. for example, by combining answers to these questions it is possible to determine if architects’ aspirations to produce sustainable buildings are supported by existing software tools. conversely, the capacity of current tools may exceed organisational needs, providing scope for expansion of those needs for limited investment. to answer these research questions, and examine what the implications of both are, this paper uses a combined method: survey and semi-structured interviews. the survey is of architects practicing in australia (n = 70) and the interviews are of 15 experienced architects. the following sections provide an introduction to sustainable design practices, and a background on research into sustainable ddes. thereafter, the survey and interview methods are described, along with their application, results and interpretation. in the case of the survey, all results are reported, whereas only those interview results that support interpretation of the survey are included here. the paper concludes with a summary of results, their implications and methodological limitations. 7 journal of sustainable architecture and civil engineering 2021/2/29 ddes and sustainability one widely accepted definition of “sustainability” involves meeting “the needs of the present without compromising the ability of future generations to meet their own needs” (report, 1987, p 41). sustainability affects society, the environment and economy in different ways. the building industry is often identified as having the potential to substantially reduce energy requirements – consumed in the construction process, used during a building life-cycle, and embodied in its demolition stage – through sustainable design (akadiri et al., 2012; biswas, 2014). the intention of sustainable design is to “eliminate negative environmental impact completely through skilful, sensitive design” (mclennan, 2004, p 5). in practice, to achieve this goal often requires architects to use ddes to support the creation of efficient and responsive buildings, which meet environmental, social and economic demands. typically, ddes are used for modelling, analysis and optimisation of design options, in order to select the best solution from potential candidate solutions. sustainable design practitioners use multiple ddes in their workplaces. three interconnected and overlapping types of ddes are a useful starting point for understanding them and the research undertaken in this field: (i) stand-alone sustainable design analysis and simulation tools, (ii) architectural design software that integrates building performance analysis or simulation, and (iii) parametric simulation tools. in the first category are analysis and simulation software for sustainable design which were, originally created as stand-alone tools. for example, energyplus is opensource software, which has the advantage of flexibility. sefaira is a component of the sketchup platform, which has a broad user base and is relatively user-friendly and easy to learn. ecotect was developed by autodesk and in 2015 it was merged into revit to support integration throughout the design process. past research has used energyplus for simulation of indoor climates (buechler et al., 2017) and optimizing of cooling loads and daylighting levels in buildings (samaan et al., 2018). from these examples it is also apparent that over time, the first category of ddes is gradually merging into the second. the second category of ddes integrate sustainable design software into a larger platform. examples of these ddes include autocad, solidworks and microstation, all of which support fast numerical and geometric operations and include functions for modelling and simulating various aspects of sustainability. building information modelling (bim) platforms, like autodesk revit or archicad, also often feature integrated building performance analysis or simulation capacity, such as green building studio. xu et al. (2018) conducted a survey (20 responses) to examine the use of bim in the aec industry, particularly on the application of this software to sustainable design. their results indicate that bim software is predominately useful in the areas of analysis and visualization, but also supports orientation of projects and modelling of daylighting, ventilation and energy efficiency. their research suggests that the most two common issues with these types of software are: designers’ inadequate knowledge or practical experience using the software, and a lack of their clients’ appreciation of the applications and benefits of the software. the third category of ddes for sustainability is parametric software. yu et al. (2013) define parametric design as “a dynamic, rule-based process controlled by variations and constraints, in which multiple design solutions can be developed in parallel” (p 622). two of the advantages of parametric design are that it can support decision optimisation and that some parametric tools can be customised to suit specific building performance requirements. examples of parametric design tools are generativecomponents by bentley and digital project by gehry technologies. among the most commonly used parametric tools are rhino, a stand-alone nurbs-based 3d modelling tool, and grasshopper, a graphical algorithm editor which is integrated into rhino as a plug-in. some examples of grasshopper plug-in tools used for energy simulation are honeybee and ladybug. those tools assist designers to generate multiple compliant design solutions and then test building performance for each solution. however, evaluating and selecting design candidate solutions background journal of sustainable architecture and civil engineering 2021/2/29 8 can be difficult and time-consuming (wynn & clarkson, 2018). one of the advantages of parametric ddes is that they can support serial and parallel optimization and analysis. in a parametric dde, sets of input design variables are evolved automatically by an algorithm in order to achieve more compliant or optimal outputs. for example, contextual data such as sunlight direction can be input and analysed within a dde. sustainability performance analysis of this type is studied in various ways. for example, multi-parametric façade elements in a bim model can be examined, so that designers can better consider energy performance while they are modelling geometries (schlueter & thesseling, 2008). bernal (2011) proposed a design model that combines parametric modelling technologies with a performance-based design paradigm. with similarities to schlueter and thesseling’s (2008) model, bernal provides real-time feedback on the building performance index. he et al. (2020) explored the use of a parametric design, simulation and analysis method (integrating computational fluid dynamics) to simulate wind environments for architectural design. research into ddes and sustainability to a significant extent, the effectiveness of sustainable design practice is tied up in the capacity of ddes to answer users’ needs. the research cited in each of the three types of ddes above tends to be technical in nature, considering solutions to improve building performance modelling (he et al., 2020; schlueter & thesseling, 2008). in contrast, multiple studies have examined the reasons why ddes have not been more widely adopted, and these point to problems of individual perception and to organisational factors (sepasgozar and davis 2018; liu et al. 2018). such human factors can differ between regions, highlighting the need for national or regional studies into both sustainable design practices and architects’ perceptions of the usefulness of ddes for supporting sustainable design. for example, utilising focus group interviews (26 participants), martek et al. (2019) investigated four organisational and contextual barriers to creating sustainable buildings in australia: (i) problems of socio-spatial embedding, (ii) lack of end-user demand, (iii) limited user awareness and (iv) industry. reflecting several of these problems, whittem and roetzel (2019) explored postoccupancy practices in australia, through interviews with six practitioners, identifying three barriers: client’s attitudes to sustainability, the impacts of “cost-engineering” on building performance, and procurement and contractual methods which discourage detailed modelling and post-completion assessment. these barriers, and availability of appropriate ddes, are factors in australia’s capacity to conform to the un’s sdgs (loh et al. (2020). soebarto et al. (2015) conducted an online survey with participants in australia, uk, india and usa, to explore architects’ views on the difficulties of using building performance simulations (bps). results of their study suggest that most architects do not include bps in their design process. some of the reasons for this include the high cost of software, the cost of outsourcing bps to external consultants, and architect’s contractual fee structures. in an international study, oliveira et al. (2017) used semi-structured interviews and focus groups (26 participants) to investigate architects’ early-stage design decisions when using energy modelling tools in their design practice. naboni (2014) interviewed sustainable design experts from ten leading architectural companies, showing that these architectural firms have design strategies and digital tools in place to facilitate their sustainable design, agendas. weytjens and verbeeck (2010) used interviews with nine architects and a survey to examine the use of energy evaluation tools in the architectural industry, finding that better tools and ddes are needed. the studies described in this section are just a few examples of the extensive body or technical research into ddes for sustainable design that exist, as well as research into the barriers to dde adoption for such purposes. in such research it is notable that in australia, as in most of the international research, perceptual and organisational issues are typically not covered. a further observation is that only one of the studies cited in the previous section had more than 20 participants, which partially reflects the limited pool of expert respondents in most countries, 9 journal of sustainable architecture and civil engineering 2021/2/29 including australia. to respond to this situation, this paper is focused on the junction between architects’ perceptions of, or aspirations for, sustainable design and their views about the capacity of ddes to assist sustainable design. the combined method used in this paper balances the need for in-depth data gathering with a survey to attract a larger number of responses than are found in most previous studies. this research employs a combined method – online survey and semi-structured interviews – to explore two research questions about (1) architects’ experiences of, and attitudes to using ddes to design sustainable buildings, and (2) the ways sustainable design is considered within architectural practice. the specific questions developed for both the survey and the interviews are synthesised from the literature reviewed. these questions combine general, demographic or fact-finding queries, with more nuanced and focused prompts. survey despite small response rates, research into ddes in architecture often employs surveys to comment on broad trends in the field. for the present paper, an online survey containing 25 questions was sent to people employed in architectural practices in australia. the survey notes and explanations made it clear that it was seeking people who (i) had used ddes to support the production of sustainable designs and (ii) possessed professional qualifications in the architectural field. these factors limited the potential number of responses but also sought to find the most experienced participants who could provide the most valid and informed answers. the survey included multiple choice questions, likert-scale questions and “open text” questions. some of the questions were ‘general’ in nature, to construct a broader picture of the field, whereas others addressed specific issues aligned to the aims of this paper. there were four parts to the questionnaire. 1. demographic questions (age, gender, location and specific design area). 2. participants’ views regarding the use of ddes in their architectural design practices (including digital design tools applied in various design stages, the benefits of using digital design tools, etc). this section provides context for the next two, by asking broad questions about participant’s experience using ddes. 3. architects’ evaluation of sustainable design goals and applications within their practices (including whether or not their workplace has been actively pursuing sustainability objectives, and whether it forms an important part of their strategic plan). this section addresses research question 2. 4. architects’ experiences using ddes to support sustainable design practices (including which particular sustainable ddes they use, at what design stages they are used, which tool features are considered most important, and whether or not the current sustainable ddes are considered helpful in achieving the architect’s sustainable design goals). this section addresses research question 1. semi-structured interviews the interview has been the most common method used in past research to investigate australian architects’ attitudes to sustainability and technology. interviews, which are ideal for collecting detailed responses to issues, can be semi-structured, lightly structured or in-depth (mason, 1994). the semi-structured interview calls for the use of predesigned questions, which focus the participant’s answers on the desired information, while also giving them some flexibility to explore issues. for the present research, the interview questions were designed to respond to gaps identified in the literature about the conjunction between sustainable design practice and aspirations (future-focused) and digital design tools for supporting sustainable practice (present-focused). the interview questions allow for open responses and to develop a conversational interchange, research method journal of sustainable architecture and civil engineering 2021/2/29 10 revealing deeper aspects of the issue being investigated. some questions were also designed with follow-up prompts or clarifications. importantly, by setting the scope at the start of the interview, the more open-ended questions retained a focus on the key research themes. table 1 shows the predesigned prompts including three background questions and 10 focused on the main themes. table 1 interview questions background questions: 1 how many years of professional architectural working experience do you have? 2 what types of buildings are your main focus? 3 where are you currently working, and where have you worked previously? main themes: 1 what are the main digital tools you are using in your practice? 2 what do you think of current digital tools, in terms of their capacity to support or challenge design thinking and creativity? 3 what do you feel is the extent, of the application of sustainable design principles in current architectural design practice? 4 is sustainable design currently considered at every scale in your practice, in the projects that your workplace undertakes? if not, then what obstacles are currently preventing that? in your experience do clients care about sustainability? 5 what do you think of current digital tools, in terms of their ability to support sustainable design? what do you think are the biggest challenges currently in this area? 6 what do you think about the possible future directions of architectural design for sustainability? 7 do you predict that computational design tools will play an increasingly large part in the future of sustainable design? do you think that advanced artificial intelligence (ai) computing, may eventually change the role of architects? 8 what do you think may be the future direction for sustainable design? 9 how could sustainable design principles be more widely applied? 10 do you think that computational design tools will play a more or less important role in promoting sustainable design? table 2 codes for interview content main themes codes sustainable design practice designer’s current practice clients aspect of sustainable design considered evaluation of sustainable design practices regulation variation between practices future of sustainable design future trend promoting of sustainable design digital design tools digital thinking and computational design digital design tools improvement of digital design tools for the present paper, participants in the online survey were invited to take part in a detailed, follow-up interview. thus, like the survey respondents, interview participants were working in australian architectural practices, possessed professional qualifications in architecture and had at least five years’ experience using ddes. the interviews typically took 30 minutes to complete and the content was transcribed and coded using nvivo. three main themes and 11 codes were developed from the literature review, and cross-referenced with the survey results. as with the survey, one set of codes is about background conditions and the other two address the research questions (table 2). 11 journal of sustainable architecture and civil engineering 2021/2/29 70 participants took part in the survey, although some did not complete all questions. for some questions there were as few as 57 complete responses, whereas for others it was 70. because of this, the data is typically reported here as the percentage of the total number of responses to the question. participants included architectural specialists in residential (n = 33), commercial (n = 18), health (n = 8), recreational and educational building design (n = 18). some (n = 6) participants also identified expertise in urban design, landscape architecture and interior design (note that participants were able to identify multiple specialist areas). participants were based in multiple cities throughout australia, although the majority were from brisbane, sydney and melbourne. 69.7% of the participants identified as male and 30.3% as female. participants were mostly in their 30s (31.82%), 40s (27.27%) or 50s (25.76%), with relatively few in their 20s (15.15%). digital design tools in architectural design practice the second section of the survey focused on participants’ perceptions about ddes. questions focused on the specific tools they were using, the design stages they applied them to, the features participants favoured and their experiences using these tools. participants were allowed to select multiple answers for this question, since they may use multiple ddes in their design practice. fig. 1 shows the digital tools participants used in their practices. revit and sketchup are the most commonly used ddes, accounting for 57.81% and 48.44% respectively. these are followed by archicad (37.50%) and autocad (35.94%). geometric modelling-focused tools such as rhino (12.50%), grasshopper (14.60%) and 3dmax (17.19%) were the lowest percentage. other tools that designers used included the adobe suite (photoshop, illustrator, indesign), lumion, vectorworks, navisworks, dynamo, bim 360, microstation, vary and enscape. results fig. 1 digital design tools used by participants (note that participants could select multiple tools) figure 1. digital design tools used by participants (note that participants could select multiple tools). the digital tools participants commonly use across design stages (pre-design, concept design, schematic design, detail design and developed design) are identified in figure 2. across these stages, participants mostly used revit and archicad, except for pre-design and concept design stages, where sketchup dominated. revit is used more towards the later design stages (typically developed design). additionally, in the open text responses participants mentioned that “it is not easy to use the available digital tools for the concept design stage”. figure 2. digital tools participants use in different design stages in figure 3, participant’s opinions about the benefits of using ddes and the design processes that ddes assist are identified. in this data, 63.33% of participants considered visual representation the most important benefit of using digital design tools. this is followed by multidisciplinary collaboration (11.67%), intradisciplinary collaboration (10.00%), flexible and friendly user interface (8.33%) and rule-based design generation (6.67%). in terms of the design process, synthesis is considered the most important process that these tools assist (47.46%), followed by analysis (22.03%) and evaluation (30.51%). synthesis in architecture refers to the merging of information that is relevant to the design the digital tools participants commonly use across design stages (pre-design, concept design, schematic design, detail design and developed design) are identified in fig. 2. across these stages, participants mostly used revit and archicad, except for pre-design and concept design stages, where sketchup dominated. revit is used more towards the later design stages (typically developed design). additionally, in the open text responses participants mentioned that “it is not easy to use the available digital tools for the concept design stage”. in fig. 3, participant’s opinions about the benefits of using ddes and the design processes that ddes assist are identified. in this data, 63.33% of participants considered visual representation the most important benefit of using digital design tools. this is followed by multidisciplinary collaboration (11.67%), intradisciplinary collaboration (10.00%), flexible and friendly user interface (8.33%) journal of sustainable architecture and civil engineering 2021/2/29 12 fig. 2 digital tools participants use in different design stages figure 1. digital design tools used by participants (note that participants could select multiple tools). the digital tools participants commonly use across design stages (pre-design, concept design, schematic design, detail design and developed design) are identified in figure 2. across these stages, participants mostly used revit and archicad, except for pre-design and concept design stages, where sketchup dominated. revit is used more towards the later design stages (typically developed design). additionally, in the open text responses participants mentioned that “it is not easy to use the available digital tools for the concept design stage”. figure 2. digital tools participants use in different design stages in figure 3, participant’s opinions about the benefits of using ddes and the design processes that ddes assist are identified. in this data, 63.33% of participants considered visual representation the most important benefit of using digital design tools. this is followed by multidisciplinary collaboration (11.67%), intradisciplinary collaboration (10.00%), flexible and friendly user interface (8.33%) and rule-based design generation (6.67%). in terms of the design process, synthesis is considered the most important process that these tools assist (47.46%), followed by analysis (22.03%) and evaluation (30.51%). synthesis in architecture refers to the merging of information that is relevant to the design project, to create appropriate architectural responses to the specified context. the cognitive importance of visual representation (63.33%) is that in the early design stages it supports concept development by “off-loading cognition” (schön & wiggins, 1992; schön, 1992). figure 3. uses of digital design tools (left). design process which digital design tools assist (right). table 3 reports the likert scale results for participants’ evaluation of current ddes. most participants agree that such tools, systems and platforms assist them to formulate sustainable design solutions. in answering the question about their proficiency in using these tools, and the impact of this, responses tended to be neutral and with less agreement. this result may also reflect some ambivalence about ddes, as one participant commented: “overreliance on digital design can have a negative influence on the free-flowing nature of design. software cannot replace good basic designs.” table 3. participants’ evaluation of digital design tools (strongly agree = 5, agree = 4, neutral = 3, disagree = 2, strongly disagree = 1). question mean sd 1 digital design tools assist me in formulating my design solution. 4.12 0.80 2 my proficiency level in the use of digital design tools has a big impact on my design. 3.34 1.24 the open questions were included to explore participants’ experiences using ddes and not all participants chose to answer these. two participants who did, stated that utilisation of these tools allowed them to integrate and optimise designs for better outcomes. conversely, four participants expressed the view that modern technological tools were akin to a drawing board that can be used to produce design documents but should only support the design process not replace it. two participants believed that digital design tools should support and facilitate transmission of ideas about site-specific and well-considered design outcomes, but rarely results in such approaches. 4.2. sustainable design goals in architectural practice the third section of the survey gathered participants’ opinions regarding the application of sustainable design in their design practice (table 4). from this data we can see that most participants and rule-based design generation (6.67%). in terms of the design process, synthesis is considered the most important process that these tools assist (47.46%), followed by analysis (22.03%) and evaluation (30.51%). synthesis in architecture refers to the merging of information that is relevant to the design project, to create appropriate architectural responses to the specified context. the cognitive importance of visual representation (63.33%) is that in the early design stages it supports concept development by “off-loading cognition” (schön & wiggins, 1992; schön, 1992). table 3 reports the likert scale results for participants’ evaluation of current ddes. most participants agree that such tools, systems and platforms assist them to formulate sustainable design solutions. in answering the question about their proficiency in using these tools, and the impact of this, responses tended to be neutral and with less agreement. this result may also reflect some ambivalence about ddes, as one participant commented: “overreliance on digital design can have a negative influence on the free-flowing nature of design. software cannot replace good basic designs.” fig. 3 uses of digital design tools (left). design process which digital design tools assist (right) table 3 participants’ evaluation of digital design tools question mean sd 1 digital design tools assist me in formulating my design solution. 4.12 0.80 2 my proficiency level in the use of digital design tools has a big impact on my design. 3.34 1.24 (strongly agree = 5, agree = 4, neutral = 3, disagree = 2, strongly disagree = 1) 13 journal of sustainable architecture and civil engineering 2021/2/29 the open questions were included to explore participants’ experiences using ddes and not all participants chose to answer these. two participants who did, stated that utilisation of these tools allowed them to integrate and optimise designs for better outcomes. conversely, four participants expressed the view that modern technological tools were akin to a drawing board that can be used to produce design documents but should only support the design process not replace it. two participants believed that digital design tools should support and facilitate transmission of ideas about site-specific and well-considered design outcomes, but rarely results in such approaches. sustainable design goals in architectural practice the third section of the survey gathered participants’ opinions regarding the application of sustainable design in their design practice (table 4). from this data we can see that most participants agree that their workplace actively pursues sustainable objectives and that sustainability is important in their practice. table 4 participant’s evaluation of how sustainable design is applied in their practice question mean sd 1 my workplace actively pursues sustainability objectives in relation to preliminary client design work. 3.95 0.89 2 setting up sustainability objectives is an important part of my design practice. 4.09 0.82 (strongly agree = 5, agree = 4, neutral = 3, disagree = 2, strongly disagree = 1) fig. 4 identifies the applications or areas of sustainable design that participants considered most important. participants were allowed to select multiple answers for this question. the results show that energy (38.60%) and heating/cooling (26.32%) are weighted more highly than other applications. participants also stated in the open-text responses, that all aspects of sustainable design were important to them, including passive sun control, waste, ventilation and global footprint. the open questions also asked participants’ opinions about sustainable design in their practice. four responded that they always try to incorporate passive solar design strategies and cross ventilation for heating and cooling, fig. 4 aspects of sustainable design considered to be most important agree that their workplace actively pursues sustainable objectives and that sustainability is important in their practice. table 4. participant’s evaluation of how sustainable design is applied in their practice (strongly agree = 5, agree = 4, neutral = 3, disagree = 2, strongly disagree = 1). question mean sd 1 my workplace actively pursues sustainability objectives in relation to preliminary client design work. 3.95 0.89 2 setting up sustainability objectives is an important part of my design practice. 4.09 0.82 figure 4 identifies the applications or areas of sustainable design that participants considered most important. participants were allowed to select multiple answers for this question. the results show that energy (38.60%) and heating/cooling (26.32%) are weighted more highly than other applications. participants also stated in the open-text responses, that all aspects of sustainable design were important to them, including passive sun control, waste, ventilation and global footprint. figure 4. aspects of sustainable design considered to be most important the open questions also asked participants’ opinions about sustainable design in their practice. four responded that they always try to incorporate passive solar design strategies and cross ventilation for heating and cooling, and consider this essential to a good design outcome. two participants emphasised that a focus on local sustainable and healthy production and sourcing of materials and systems is crucial. there were also participants who noted that sustainable design is “not used heavily in practice”. 4.3. evaluating ddes in sustainable design practice the final section of the survey examines the effectiveness of ddes in sustainable design practice (table 5). the data shows that participants generally had a positive attitude towards current ddes, and tended to agree that they are helpful, especially for the design analysis and optimization processes to support sustainability. however, the mean score was only moderately positive (3.59 – 3.91), which and consider this essential to a good design outcome. two participants emphasised that a focus on local sustainable and healthy production and sourcing of materials and systems is crucial. there were also participants who noted that sustainable design is “not used heavily in practice”. evaluating ddes in sustainable design practice the final section of the survey examines the effectiveness of ddes in sustainable design practice (table 5). the data shows that participants generally had a positive attitude towards current ddes, and tended to agree that they are helpful, especially for the design analysis and optimization processes to support sustainability. however, the mean score was only moderately positive (3.59 – 3.91), which suggests there is room for improvement and that ddes could be even more effective for enabling sustainable design practices. journal of sustainable architecture and civil engineering 2021/2/29 14 fig. 5 shows the ddes that participants use for sustainable design, and surprisingly it records that 65.52% do not personally use ddes for sustainability modelling and support. this finding is in stark contrast to the aspirations and claims recorded previously in the survey, and it highlights either the lack of appropriate sustainable design tools or other barriers to adoption of ddes for sustainable design. 10.34% of the participants were using rhino/grasshopper, followed by safaira (8.62%) and ecotect (8.62%). use of vasary and green building studio are each 5.17% and energyplus is 3.45%. participants also listed other tools they use including archicad for sun studies, empirical design principle, climate consultant, vasari, dynamo and refinery. several participants noted that specialist external energy consultants are involved in their design projects, suggesting that sustainability modelling and analysis largely occur outside the design practices. rhino and grasshopper were used more frequently than traditional energy simulation tools in ddes. this may be due to the flexible features of the parametric tools which allow for customisation for specific design project needs. table 5 participants’ evaluation of ddes for sustainability in their practice question mean sd 1 sustainable design digital tools are helpful with sustainable goal setting. 3.69 0.84 2 sustainable design digital tools are helpful during design analysis. 3.87 0.73 3 sustainable design digital tools are helpful during design optimisation. 3.91 0.78 4 the sustainable design digital tools being used are effective in achieving sustainable design goals. 3.59 0.85 (strongly agree = 5, agree = 4, neutral = 3, disagree = 2, strongly disagree = 1) fig. 5 participant use of sustainable design digital tools suggests there is room for improvement and that ddes could be even more effective for enabling sustainable design practices. table 5. participants’ evaluation of ddes for sustainability in their practice. (strongly agree = 5, agree = 4, neutral = 3, disagree = 2, strongly disagree = 1). question mean sd 1 sustainable design digital tools are helpful with sustainable goal setting. 3.69 0.84 2 sustainable design digital tools are helpful during design analysis. 3.87 0.73 3 sustainable design digital tools are helpful during design optimisation. 3.91 0.78 4 the sustainable design digital tools being used are effective in achieving sustainable design goals. 3.59 0.85 figure 5 shows the ddes that participants use for sustainable design, and surprisingly it records that 65.52% do not personally use ddes for sustainability modelling and support. this finding is in stark contrast to the aspirations and claims recorded previously in the survey, and it highlights either the lack of appropriate sustainable design tools or other barriers to adoption of ddes for sustainable design. 10.34% of the participants were using rhino/grasshopper, followed by safaira (8.62%) and ecotect (8.62%). use of vasary and green building studio are each 5.17% and energyplus is 3.45%. participants also listed other tools they use including archicad for sun studies, empirical design principle, climate consultant, vasari, dynamo and refinery. several participants noted that specialist external energy consultants are involved in their design projects, suggesting that sustainability modelling and analysis largely occur outside the design practices. rhino and grasshopper were used more frequently than traditional energy simulation tools in ddes. this may be due to the flexible features of the parametric tools which allow for customisation for specific design project needs. fig. 6 shows the design stages in which participants typically use ddes to support sustainability and their primary features that participants use. from these results we can see that ddes are more likely to be applied in the concept design stage (29.82%) when designers are developing their initial ideas. schematic design (24.56%) is the next more common, followed by developed design (17.54%), pre-design (15.79%) and detail design (12.28%). the primary features of ddes that 15 journal of sustainable architecture and civil engineering 2021/2/29 fig. 6 the design stage in which the participants most typically apply ddes for sustainability (left). the primary feature of ddes that participants apply within their sustainable design practice (right) figure 5. participant use of sustainable design digital tools figure 6 shows the design stages in which participants typically use ddes to support sustainability and their primary features that participants use. from these results we can see that ddes are more likely to be applied in the concept design stage (29.82%) when designers are developing their initial ideas. schematic design (24.56%) is the next more common, followed by developed design (17.54%), predesign (15.79%) and detail design (12.28%). the primary features of ddes that participants use most often are weather or climate data (36.84%) and 3d model building (22.81%), followed by optimization of design (21.05%) and energy analysis (17.54%). figure 6. the design stage in which the participants most typically apply ddes for sustainability (left). the primary feature of ddes that participants apply within their sustainable design practice (right). focusing on sustainable design, figure 7 shows the features of ddes that participants most favour. 31.58% consider the most important feature of ddes is their integration of a best practice design knowledge base, to assist designers in intelligent decision making. that feature is followed by support for high-quality 3d modelling of proposals (15.79%). only 12.28% of participants identify energy analysis results and friendly user interfaces. based on these results, a capacity for transferable export/import from other design software was considered the least critical (3.51%). participants use most often are weather or climate data (36.84%) and 3d model building (22.81%), followed by optimization of design (21.05%) and energy analysis (17.54%). focusing on sustainable design, fig. 7 shows the features of ddes that participants most favour. 31.58% consider the most important feature of ddes is their integration of a best practice design knowledge base, to assist designers in intelligent decision making. that feature is followed by support for high-quality 3d modelling of proposals (15.79%). only 12.28% of participants identify energy analysis results and friendly user interfaces. based on these results, a capacity for transferable export/import from other design software was considered the least critical (3.51%). fig. 7 primary dde features that participants favour figure 7. primary dde features that participants favour. the open questions in the survey were used to explore participants’ views about current ddes. some participants viewed autodesk’s move to a subscription licensing model as undermining their sustainable design goals, while grasshopper’s open-source approach was more supported. participants also argued that it was important that tools possess a capacity to present information to clients, in such a way as to explain sustainable principles and easily modify designs based on those principles. this was also considered necessary for balancing costs and time investment in such a way that clients can appreciate and embrace sustainability. some participants noted that a seamless data exchange between software systems would be beneficial. other comments touched upon specific building codes (ncc and australian standards) discussing embodied energy in design and construction options for single residences, and a shift in the goals of state-wide certification systems (basix), including targets for construction waste. participants expressed the view that there was a need to reward higher sustainability “ratings” or “scores” with incentives, rather than focusing on minimum standards. participants also voiced the opinion that ddes shouldn’t be a replacement for design professionals having fundamental knowledge of sustainable design practices from the outset. 4.4. selected interview results two sets of interview coding results are reported in this section to support interpretation of the survey results. figure 8 shows the coding percentage of the 15 interviewees’ answers. this data indicates that the most discussed theme was the use of digital design tools in architects’ current practice. this is followed by: evaluation of sustainable design practice, aspects of sustainable design considered and promoting sustainable design. this confirms that digital design tools play an important role in architects’ design practice and that architects do consider sustainable design issues during the design process. furthermore, while both “designers’ current practice” and “digital design tools” were, for obvious reasons, central issues explored in the interviews, several others issues were also common. for example, the capacity of ddes to support “evaluation of design options”, their capacity to “promote sustainable design”, and the ways they support “design thinking” were all common, and arguably closely related, themes. conversely, “budget”, “clients briefs” and “regulations” – all prominent factors identified in the open questions in the survey were used to explore participants’ views about current ddes. some participants viewed autodesk’s move to a subscription licensing model as undermining their sustainable design goals, while grasshopper’s open-source approach was more supported. participants also argued that it was important that tools possess a capacity to present information to clients, in such a way as to explain sustainable principles and easily modify designs based on those principles. this was also considered necessary for balancing costs and time investment in such a way that clients can appreciate and embrace sustainability. some participants noted journal of sustainable architecture and civil engineering 2021/2/29 16 that a seamless data exchange between software systems would be beneficial. other comments touched upon specific building codes (ncc and australian standards) discussing embodied energy in design and construction options for single residences, and a shift in the goals of state-wide certification systems (basix), including targets for construction waste. participants expressed the view that there was a need to reward higher sustainability “ratings” or “scores” with incentives, rather than focusing on minimum standards. participants also voiced the opinion that ddes shouldn’t be a replacement for design professionals having fundamental knowledge of sustainable design practices from the outset. selected interview results two sets of interview coding results are reported in this section to support interpretation of the survey results. fig. 8 shows the coding percentage of the 15 interviewees’ answers. this data indicates that the most discussed theme was the use of digital design tools in architects’ current practice. this is followed by: evaluation of sustainable design practice, aspects of sustainable design considered and promoting sustainable design. this confirms that digital design tools play an important role in architects’ design practice and that architects do consider sustainable design issues during the design process. furthermore, while both “designers’ current practice” and “digital design tools” were, for obvious reasons, central issues explored in the interviews, several others issues were also common. for example, the capacity of ddes to support “evaluation of design options”, their capacity to “promote sustainable design”, and the ways they support “design thinking” were all common, and arguably closely related, themes. conversely, “budget”, “clients briefs” and “regulations” – all prominent factors identified in technology adoption models – were rarely mentioned. variation between practice were mentioned by some participants since for sustainable design practice different practices adopted different approaches (some were due to the scope of service they provide). fig. 8 coding of interview content technology adoption models – were rarely mentioned. variation between practice were mentioned by some participants since for sustainable design practice different practices adopted different approaches (some were due to the scope of service they provide). figure 8. coding of interview content. figure 9 shows the negative or positive experience in each of the codes. these results indicate that on average, architects had more negative than positive experiences when considering sustainable design practice, digital design tools, their current practice and available budgets. indeed, only dde’s capacity to “promote sustainable design”, support “future trends” and improve “client briefs” achieved more positive than negative mentions. as an example of why these results are useful, budgets were only rarely mentioned in the interviews (figure 8), but of these, 11 out of 13 identified financial impediments to sustainable design and the use of dde. similarly, regulation, which was also only rarely mentioned, was overwhelmingly viewed as a negative influence on sustainable design and use of ddes. the capacity of digital design tools to support sustainable design received the highest positive and negative results, although organisational incapacity to use ddes or achieve sustainable goals was the second greatest negative. for the category “variation between practice”, responses were mostly neutral although some referred to negative experiences. this is because some participants noted that sustainable design was not considered important by some design practices. one participant commented: “australia's been very slow in adopting minimum performance standards for buildings, … new zealand was doing it for houses 15 years before we were”. these last two sets of results provide additional nuance when reviewing the survey results, because both were regarded as important factors in the survey. but in the interviews, the capacity to use ddes to achieve sustainable outcomes, and to meet practice objectives, prompted more pessimistic than optimistic answers. fig. 9 shows the negative or positive experience in each of the codes. these results indicate that on average, architects had more negative than positive experiences when considering sustainable design practice, digital design tools, their current practice and available budgets. indeed, only dde’s capacity to “promote sustainable design”, support “future trends” and improve “client briefs” achieved more positive than negative mentions. as an example of why these results are useful, budgets were only rarely mentioned in the interviews (fig. 8), but of these, 11 out of 13 identified financial impediments to sustainable design and the use of dde. similarly, regulation, which was also only rarely mentioned, was overwhelmingly viewed as a negative influence on sustainable 17 journal of sustainable architecture and civil engineering 2021/2/29 design and use of ddes. the capacity of digital design tools to support sustainable design received the highest positive and negative results, although organisational incapacity to use ddes or achieve sustainable goals was the second greatest negative. for the category “variation between practice”, responses were mostly neutral although some referred to negative experiences. this is because some participants noted that sustainable design was not considered important by some design practices. one participant commented: “australia’s been very slow in adopting minimum performance standards for buildings, … new zealand was doing it for houses 15 years before we were”. these last two sets of results provide additional nuance when reviewing the survey results, because both were regarded as important factors in the survey. but in the interviews, the capacity to use ddes to achieve sustainable outcomes, and to meet practice objectives, prompted more pessimistic than optimistic answers. fig. 9 the negative or positive experience in each of the coding figure 9. the negative or positive experience in each of the coding 5. conclusion this paper set out to investigate the two research questions and the relationship between them. first, what are architects’ attitudes to, and experiences of, using ddes to design sustainable buildings? second, how is sustainable design considered within architectural practice? these two questions have both been separately considered in the past, and in other countries, but not recently and not in an australian context. furthermore, the combination of questions supports an investigation of correlation or symmetry in relation between perceptions of dde capacity and aspirations for sustainable design. starting with the first question, the main digital design tools used were revit and sketchup; the former of which was used across all design stages, while the latter was mainly used at the concept design stage. integrated sustainable design tools – ecotect, green building studio and sefaira – exist for both revit and sketchup, however most architects (65.52%) admitted to not using these for complex environmental modelling, but rather outsourcing them. among ddes, the embedded sustainability tools in rhino and grasshopper were applied more often than traditional, stand-alone energy simulation tools, which suggests a need for flexible customised parametric design tools in facilitating sustainable design. stronger integration of sustainable tools in ddes was also identified as the main way of facilitating architects’ decision-making for design, a finding which reflects that of past research (jansen and bosch (2005). architects generally do not have the time nor inclination to learn new specialised software systems. for existing dde, the data identifies interoperability as a weakness, and that visual representation and collaboration in sustainable design were the most needed features of ddes for architects. for the second question, and not surprisingly, most architects argued that their workplaces actively pursued sustainable objectives. furthermore, in relation to specific aspects of sustainable design goals, most participants confirmed that all aspects of sustainable design were important, including heating/cooling, passive sun control, waste/ventilation/energy and global footprint. when considering these factors in parallel with the first research question, several areas of asymmetry or misalignment are evident. for example, while participants strongly affirmed their aspirations for designing sustainable buildings, they identified significant barriers, most of which were technical (e.g. about dde capacity) this paper set out to investigate the two research questions and the relationship between them. first, what are architects’ attitudes to, and experiences of, using ddes to design sustainable buildings? second, how is sustainable design considered within architectural practice? these two questions have both been separately considered in the past, and in other countries, but not recently and not in an australian context. furthermore, the combination of questions supports an investigation of correlation or symmetry in relation between perceptions of dde capacity and aspirations for sustainable design. starting with the first question, the main digital design tools used were revit and sketchup; the former of which was used across all design stages, while the latter was mainly used at the concept design stage. integrated sustainable design tools – ecotect, green building studio and sefaira – exist for both revit and sketchup, however most architects (65.52%) admitted to not using these for complex environmental modelling, but rather outsourcing them. among ddes, the embedded sustainability tools in rhino and grasshopper were applied more often than traditional, stand-alone energy simulation tools, which suggests a need for flexible customised parametric design tools in facilitating sustainable design. stronger integration of sustainable tools in ddes was also identified as the main way of facilitating architects’ decision-making for design, a finding which reflects that of past research (jansen and bosch (2005). architects generally do not have the time nor inclination to learn new specialised software systems. for existing dde, the data identifies interoperability as a weakness, and that visual representation and collaboration in sustainable design were the most needed features of ddes for architects. conclusions journal of sustainable architecture and civil engineering 2021/2/29 18 for the second question, and not surprisingly, most architects argued that their workplaces actively pursued sustainable objectives. furthermore, in relation to specific aspects of sustainable design goals, most participants confirmed that all aspects of sustainable design were important, including heating/cooling, passive sun control, waste/ventilation/energy and global footprint. when considering these factors in parallel with the first research question, several areas of asymmetry or misalignment are evident. for example, while participants strongly affirmed their aspirations for designing sustainable buildings, they identified significant barriers, most of which were technical (e.g. about dde capacity) rather than about cost, time, or legislation. because the context for both the surveys and interviews was ddes and sustainability, such an emphasis may be explained as a form of confirmation bias, but the ‘positive/negative’ codings suggest that it may be more than this. possibly more than budget, legislation or organisational factors – the lack of integrated, easy to use tools for modelling sustainability in ddes may be a major factor. for example, participants expressed relatively positive attitudes towards current dde tools for sustainability and generally agreed that current tools are helpful, but also admitted to now using advanced tools for design analysis and optimization processes. the results also indicate that there is significant room for improvement in current ddes’ capacity to assist architects’ sustainable design practices. additionally, most architects stated that both regulations and their client’s requirements are vitally important in driving their sustainable design goals. although outsourcing of building performance analysis is financially beneficial, the extra communication required with external consultants sometimes delays the design process and can make their processes more complicated. outsourcing of building performance analysis tasks can also lead to missed opportunities for conducting such analysis tasks during the early stages of the design process, which could benefit the design as a holistic entity, rather than serving to simply obtain a certificate from a consultant to meet the regulatory requirement. therefore, to a certain extent, architects themselves need to be able to conduct building performance analysis and optimisation. another issue to be mindful of is the practical operability of current ddes for sustainable design, as one architect stated he hoped for the existence of “a tool that could come into my skillset that i could use… [and for which] i didn’t need to do huge amounts of training”. there are several practical limitations to this research. firstly, 70 survey responses and 15 interviews is not a particularly large sample (although it is still larger than all but one of the previous studies undertaken into this particular issue and context). the response rate was partially a result of the limited pool of architects currently working within australia and who are experienced in both sustainable design and associated software tools and platforms. the low numbers of participants also preclude more detailed statistical analyses or considerations of issues on demographic grounds (by gender, age or location). an expansion of this study could include larger samples from other international regions, to provide more statistically significant results. the results of this paper seek to enhance our understanding of architects’ experiences in relation to achieving sustainable design goals using ddes. it provides insights and new knowledge about the processes that support sustainable design solutions and architects’ aspirations to achieve them. these findings can potentially identify new strategies for increasing the application and adoption of sustainable design principles, and facilitate enhancements to sustainable design practices. references abergel, t., dean, b., & dulac, j. 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(2013). comparing designers’ problem-solving behavior in a parametric design environment and a geometric modeling environment [article]. buildings, 3(3), 621-638. https://doi.org/10.3390/buildings3030621 about the authors rongrong yu lecturer architecture & design, school of engineering and built environment, griffith university, gold coast, australia main research area computational design, design cognition address griffith university, g39 room 3.30, gold coast campus, southport, qld, 4222, australia e-mail: rongrong.yu@uon.edu.au phone: +61 7 5552 7618 orcid id: 0000-0001-6948-9543 michael j. ostwald professor, associate dean of research main research area architectural computing and visualisation methods, data visualisation and computational design address unsw built environment, faculty of arts, design & architecture, room 4026, level 4, red centre west wing, unsw sydney 2052 e-mail: m.ostwald@unsw.edu.au phone: 02 90659708 orcid id: 0000-0001-6210-6984 this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 63 journal of sustainable architecture and civil engineering 2020/2/27 several studies have shown that developing countries like nigeria that need infrastructures are top markets for architecture, engineering, and construction (aec) industry. owing to inadequate resources and economic downturn, policies regarding sustainable development and construction have gained remarkable attention. the adoption of new technologies and their effective implementation have become the only way for closing the gap with developed countries (akdag and maqsood, 2019). the construction industry is envisioned as the major driver of the economy with 5% increase in gdp growth, other sectors like health, education, transportation and the likes depend heavily on the construction industry (olanrewaju et al., 2018). the industry is divided into three sectors which include; informal sector, commercial sector, and public sector. building information modeling (bim) has greater relevance for commercial and public subsectors (alufohai, 2012). the introduction of technology to activities in the construction industry has proven beyond every reasonable doubt that the future of the industry is hinged on its adoption of technological innovations in its *corresponding author: oludolapoolanrewaju2012@gmail.com current state of building information modelling in the nigerian construction industry received 2020/01/22 accepted after revision 2020/06/19 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 63-77 doi 10.5755/j01.sace.27.2.25142 current state of building information modelling in the nigerian construction industry jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.25142 oludolapo ibrahim olanrewaju*, sunday ajiboye babarinde, comfort salihu dollahills research lab, dollasoft technologies, lagos, nigeria introduction building information modelling (bim) has been applied to various aspects of construction processes in developed countries but nigeria is yet to realize the full potentials of bim. it has greater relevance for the commercial and public subsectors as it enhances construction productivity. this study examines the current state of bim in the nigerian construction industry. the study adopted a quantitative research approach by eliciting primary data through a questionnaire which was administered to 150 respondents, of which 90 were returned and considered valid for further analysis. the data were analyzed using mean item score and pearson correlation. it was revealed that bim awareness level is only high at the design stage of a building life cycle while it is extremely low at the construction and facility management stages. also, the commonly used bim compliant software packages in the nigerian construction industry were identified to be: autodesk quantity takeoff, revit architecture, and sketchup. however, the study recommends stakeholders education, openness to new technologies, investment in bim research, and policy development. keywords: building information modelling, bim, construction industry, built environment professionals, nigeria. journal of sustainable architecture and civil engineering 2020/2/27 64 activities (maurico, 2001). bim has also been highlighted by the aec industry as a powerful design and management tool that has significant advantages over the building life cycle, design and management (yan and damian, 2008). bim acronym stands for building information model, building information modelling and building information management (babarinde, 2017). according to royal institution of chartered surveyors [rics] (2014), the concept of bim has no accepted definition due to its ever-evolving nature where new areas and frontiers are creeping into the boundaries of what it could be defined as. various definition of bim exists each of them characterized by certain key point such as in referring to bim as a “product”, a “process”, “technology”, an “innovation” or a “strategy” (babarinde, 2017). penttilä (2006) stated that “bim involves the process, policies and technology interactions to produce a method for managing importance of building design and project data in digital format or virtual through the building life cycle”. also, it is believed that bim connects all the professionals in the construction industry, this allows for information sharing within the project context and hence promotes collaborative work among professionals such as architects, contractors, surveyors, designers, and owners on a common information system. furthermore, bim was described as a digital representation of physical and functional characteristics of a facility creating a shared knowledge resource for information about it and thus forming a reliable basis for decisions during its life cycle, from conception to demolition (eastman et al., 2011; snook 2011; suranga and weddikkara, 2012). many researchers have explored the concept of bim as regards developing countries. for instance, akdag and maqsood (2019) highlighted the potentials of bim for developing countries using pakistan as the study area. similarly, olawumi and chan (2018) explored bim implementation and practices in developed economies by developing a benchmarking model that will enhance bim adoption and implementation in developing countries. furthermore, anifowose et al. (2018) assessed the adoption level of bim by the selected nigerian professionals in the built environment and revealed that less than 50% of the professionals were familiar with bim concept. few studies on bim and lack of requisite knowledge were revealed as the major deterrent to bim adoption. gamil and rahman (2019) investigated the awareness of yemen construction practitioners on the adoption of bim and identification of the dominant challenges of implementing bim in the life cycle of a construction project. even though bim provides solutions to the numerous problems inherent in the construction industry (eastman et al., 2011; aryani et al., 2013; kushwaha, 2016), it is still confronted with several challenges in the nigerian construction industry. in addition, usman (2015) stated that the individuals’ readiness presents a greater setback to bim than the process, management, and technology involved in its adoption. bim has received considerable attention in developing countries over the last decade. hence this research seeks to examine the current state of bim in the nigerian construction industry. bim use and construction professionals bim as a tool for various stakeholders of the construction industry, its usage varies from the inception of the construction to the final stage of the building whole lifecycle. various professionals like the architects, builders, estate surveyors, structural engineers, services engineer, and facility managers whose duties at times may be superimposed into various professions. the following are bim uses at different stages of a building life cycle: design stage design is usually carried out by the design team which usually comprises the architects, structural engineers, services engineer and builders depending on the project complexity. the design stage of the building occupies a vital position in the life of the building which is the stage in which all the decisions pertaining to what the building will be and consists of is made. the major uses of bim in the design stage lie in construction planning, visualization, cost estimation, 3d coordination, constructability analysis, prefabrication, sequencing and incorporating sustainability issues in the 65 journal of sustainable architecture and civil engineering 2020/2/27 design (schueter and thessling, 2008; foster, 2011). the design team is then required to produce the requirement of the client in an understandable format to all the expected project team, especially the client who is to be the financier of the project. the design team must of a necessity ensure the buildability, aesthetics, structural ability, and functionality of the building (babarinde, 2017). construction / building stage at this stage, the design has been completed and the actual construction of the facility is in progress, issues regarding building, financing and management of the facility have been finalized. the contractors have been selected and the design team of the client assumes an oversight and supervisory role to the construction stage, the contractor(s) is provided with the design details and the 3d model of the building in which he offers definite and concise addition as regards his expert knowledge on the constructability and variety of issues likely to be experienced in the course of the building use (babarinde, 2017). authors like eastman et al. (2011) and azhar et al. (2012), have highlighted construction monitoring and modelling, and fabrication as the anchor uses of bim tools in the construction stage of a building. the bim model enables the contractor’s team (architect, quantity surveyors, engineers, masons and other professionals as their service may be required) to visualize a progressive stage by stage construction process simulation, this eases the work of all parties involved by enabling the various professionals to settle constructability, durability, cost efficiency and suitability issues in the construction process. operation / facility management stage this stage of the building process has been discovered by various researchers to suffer a high level of neglect which has resulted in gross infrastructural decay in the nation. this problem can be eased by the use of bim-compliant software for managing the building incorporating operation and management decisions into the design of the facilities in which the function of each space has been decided, the maintenance has been planned and scheduled, the functionality of the components inherent in the facilities can carry the expected population without deficiencies. moreover, as stated by patacas et al. (2014) that the future of effective and efficient facility management rests on the hoar of how readily the industry has adopted the bim for the management of buildings especially high-rise building emerging in the state, which is known to present to facility managers great challenges because of the numerous aspects and component inherent in such structures. thus, this function of the facility managers is further divided into various subtasks in which bim can enhance the productivity levels of these tasks include maintenance scheduling using the construction model. building system analysis, this is done to determine the building condition, also the asset management function can be carried out using bim with the spaces adequately allotted to each use with available visual simulation tools available on bim platform, more importantly, the record model is done incorporating changes made to the building use and spaces the post-construction phase (jordani, 2010; reddy, 2012).the task of operation and management is solely the work of the facility managers which are sometimes carried out by other professionals like quantity surveyors and estate surveyors due to the lack of proliferation and adequacy of such well trained and certified facility managers (jordani, 2010). bim will enable them to carry out well-planned maintenance which is strictly adhered to, this is a new way of managing building which bim is championing its course (babarinde, 2017). bim-compliant software used by professionals building information modelling as explained earlier has three basic components which include the software used for carrying out modelling activities by the professionals in the construction industry as discussed above. table 1 gives a breakdown analysis of the various software including details of the software, its bim-related use, professionals commonly involved in its use, and bim-related services it offers to the professionals. journal of sustainable architecture and civil engineering 2020/2/27 66 s/n software use professionals services available 1. tekla structures steel and concrete detailing, structural models structural, steel and civil engineers structural designer, tedds, bimsight 2. archicad architectural bim cad architects parametric modelling and design, data interchange, remote access and collaboration 3. archifm asset planning, maintenance, reporting services facility managers, estate surveyors bim computer aided facility management software 4. green building studio analysis of green building requirement, energy analysis, interoperability green building experts, designers, contractors and planners bim-green building standards integration module. 5. masterbill integrated cad and bim enabled measurement module quantity surveyors, estate surveyors, project schedulers bim enabled estimating and scheduling (4d bim). 6. revit architecture architectural designs, structural and mep modelling architects, services and civil engineers 4d bim modelling and parametric design 7. skecthup architectural and mechanical design and models, interior design, architects, mechanical and interior designers. 3d modelling 8. powercivil integrated site, building and aerial planning design team site development 9. digital project information sharing and interoperability of various cad softwares. architects, modelers, schedulers architectural computer aided design 10. navisworks manage complement 3d design packages, 4d time simulation architects, quantity surveyors, scheduler, project managers. roamer, publisher, clash detective, autodesk renderer, quantification, timeliner, animator, scripter 11. autodesk quantity takeoff quantity take-offs quantity surveyors, scheduler 3d and cad enabled quantity taking off 12. vico software virtual construction, quantity take-offs, project scheduling, cost estimation, production control. contractors, quantity surveyors, scheduler, 5d bim virtual construction 13. bentley bim suite architectural designs, structural and mep modelling, architects, services and civil engineers architectural, engineering and construction, 3d modelling 14. qs cad quantity take-offs quantity surveyors 3d and cad enabled quantity taking off table 1 bim software and tools analysis source: ibrahim and abdullahi (2016); babarinde (2017). 67 journal of sustainable architecture and civil engineering 2020/2/27 the adoption of bim as a way of representing building information in 3d and other obtainable dimensions has ushered the construction industry into a new digital construction renaissance, where projects are being built twice, once in the computer and then once flawlessly on-site (building information modelling guide, 2013). all over the world, bim is significantly modifying the way that the construction industry creates and cares for its assets; this is because, it allows organizations to identify and resolve issues before they happen, optimize outcomes and reduce process waste, especially rework. bim has a potential to be used at all stages of the project life-cycle from being used by the owner, by the design team, by the contractor and by the facility managers (grilo and jardim-goncalves, 2010). in fact, bim is very essential at all stages of the project lifecycle: from being used by the client to understand and express the project’s requirements, to the design team from the conceptual design to the full development of the project, to the contractor to manage the project from site clearing to the commissioning and by the facility manager from operation to decommissioning phases. the future of bim will lead to virtual project designs and construction approach, with a project being completely simulated before being undertaken for real (froese, 2010). adoption of building information modelling as a practice and culture in different countries varies as a result of their perception of new technological innovations and the necessary framework for adopting the innovation. the only project in which bim is implemented fully i.e from conception to construction stage in nigeria is the eko-atlantic city project which commenced in 2010 and still ongoing. the project is aimed at restoring land lost to coastal erosion over the last century (adelekan, 2012). it is a public-private partnership-based type of project between south energy x and lagos government. it uses an information-sharing platform referred to as eko-atlantic mobile application (eama) and augmented reality (ar). the eama is an easy to use application which is regularly updating project presentation, featuring an enhanced virtual tour; this enables easy navigation for the users across the construction works by moving their mobile devices around (olugboyega, 2016). various countries of the world are striving to enshrine bim into construction activities, with the united kingdom being at the forefront of this, they necessitated and mandated it that all public projects should be carried out using the bim thus showing their national disposition to the bringing bim as the model for all projects (babarinde, 2017). as stated by jensen and johannesson (2014), bim use is observed to be very limited and recommendations were made for cooperation with governmental authorities towards formulating standard and guidelines related to bim, these were observed to be obtainable in denmark and iceland. wong et al. (2008) positioned the north america and scandinavian regions of the world as the construction industry leaders in bim development and implementation with the adoption by project team professionals soaring from 17% in 2007 to 71% in 2012 putting them in the mainstream of bim usage (mcgraw hill construction, 2013). this dramatic change was catalyzed by the establishment of a national 3d-4dbim program through its public buildings services (pbs) office. similarly, in the united states (us) significant increases were recorded following the release of two major reports by national institute of standards and technology (nist) that measured the cost implications of interoperability issues witnessed in the us construction industry. united kingdom (uk) is also an emerging world leader in the implementation of bim, with the country’s building and construction authority championing its cause by mandating its use on public sector projects by 2015 (granholm, 2011). singapore has adopted the industry foundation classes (ifc) as a basis of standard for bim implementation in their country, hence localizing the standards to design standards in their country (buildingsmart, 2012). adoption of building information modelling journal of sustainable architecture and civil engineering 2020/2/27 68 figure 1. corporate tower. figure 2. azuri peninsula sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 3. marina residences figure 4. southern boulevard. sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 5. eko pearl towers figure 6. atlantic resort (internal). sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) fig. 1 corporate tower sources: eko brochure (2013); south energy (2013); olugboyega (2016). figure 1. corporate tower. figure 2. azuri peninsula sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 3. marina residences figure 4. southern boulevard. sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 5. eko pearl towers figure 6. atlantic resort (internal). sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) fig. 2 azuri peninsula sources: eko brochure (2013); south energy (2013); olugboyega (2016). figure 1. corporate tower. figure 2. azuri peninsula sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 3. marina residences figure 4. southern boulevard. sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 5. eko pearl towers figure 6. atlantic resort (internal). sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016). fig. 3 marina residences sources: eko brochure (2013); south energy (2013); olugboyega (2016). fig. 4 southern boulevard figure 1. corporate tower. figure 2. azuri peninsula sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 3. marina residences figure 4. southern boulevard. sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 5. eko pearl towers figure 6. atlantic resort (internal). sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) eko atlantic city and bim adoption the history of eko atlantic city (eac) can be traced back to 2003 when lagos state government was in search of the best way to solve coastal erosion problems at the bar beach off victoria island. between 2003 and 2005, efforts were channelled towards investigating the project feasibility in solving coastal erosion problems. this gave birth to a new city with the sole purpose of protecting shorelines and providing more housing unit (eko atlantic, 2016). eac is a unique city intended to originate from the atlantic ocean and is being created to revamp the shorelines of victoria island that have been destroyed as a result of coastal erosion. the construction of the city was executed under a public-private partnership between south energy x nigeria limited (senl) and lagos state government. the city is aimed at making nigeria one of the attractive tourist destination in africa which will foster economic development (channels television, 2010; ajibade, 2017). in terms of power administration, the city is categorized as its metropolis and will operate on its administration. it will likewise be a seaward financial zone and permit free movement of capital by speculators (olugboyega, 2016). the city is specially designed for a wide range of activities including financial, residential, tourists’ accommodation, commercial and leisure activities. upon completion of the project, it is expected to accommodate 250,000 inhabitants and 150,000 commuters. in addition, it is anticipated to have 10 districts which include; business districts, harbor lights, marina districts, downtown, eko island, avenues, four bridges, eko drive, east side marina and ocean front. the design of the city is exceptional as it encompasses independent power supply and water treatment, advanced telecommunications, low carbon footprint, no on-street parking, international school and hospital which were all included in eac bim model (south energy, 2013; channels television, 2014; eko atlantic, 2016). oyedeji (2014) added that most buildings in the eac project were high-rise buildings with setbacks to minimize the effect of shadows on infrastructures. some of these buildings are named as follows; eko corporate tower, eko boulevard, le reve tower, afren tower, eko 69 journal of sustainable architecture and civil engineering 2020/2/27 pearl towers (champagne pearl, white pearl, black pearl, indigo pearl, and acqua pearl), azuri peninsula, arep towers, international school, atlantic business and residence, eko mall, eko energy estate, 3-marinas, and eko atlantic medical centre (cf. olugboyega, 2016). in terms of value, meseko (2014) revealed the cost of waterfront and inner-city plots to be $2,000/ sqm and $1,000/sqm respectively while the estimated project cost stood at $6 billion. olugboyega (2016) acknowledged the vital role played by bim in eac project as it ensures that all aspect of the project was fully captured without omissions. bim is a significant tool in the enhancing lifecycle and knowledge sharing in the construction project (olanrewaju et al., 2020). despite this importance, bim is yet to be fully implemented in most construction projects as anifowose et al. (2018) recorded a 40% level of awareness. the eac project demonstrated the significant benefits that can be derived from the full implementation of bim in the nigerian construction industry. fig.1-6 shows some of the bim models developed for the eac project. methods fig. 5 eko pearl towers sources: eko brochure (2013); south energy (2013); olugboyega (2016). fig. 6 atlantic resort (internal) sources: eko brochure (2013); south energy (2013); olugboyega (2016). figure 1. corporate tower. figure 2. azuri peninsula sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 3. marina residences figure 4. southern boulevard. sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 5. eko pearl towers figure 6. atlantic resort (internal). sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 1. corporate tower. figure 2. azuri peninsula sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 3. marina residences figure 4. southern boulevard. sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) figure 5. eko pearl towers figure 6. atlantic resort (internal). sources: eko brochure (2013); south energy (2013); olugboyega (2016) sources: eko brochure (2013); south energy (2013); olugboyega (2016) the research process for this study is divided into four distinctive processes namely; literature survey, questionnaire design and distribution, questionnaire collection and data analysis, and presentation of the result as shown in fig. 7. a similar approach was adopted in olanrewaju and okorie (2019) for dividing research into stages. to achieve the objectives of this study, a literature survey was conducted on bim uses, bim and software packages.the quantitative research approach was adopted for this study. furthermore, the review of relevant literature resulted in the formulation of a structured questionnaire based on 5-point likert-scale measurement. collins (2010) maintains that likert scales are effective to elicit participants’ opinions on various statements. fig. 7 research processes methods the research process for this study is divided into four distinctive processes namely; literature survey, questionnaire design and distribution, questionnaire collection and data analysis, and presentation of result as shown in figure 7. similar approach was adopted in olanrewaju and okorie (2019) for dividing research into stages. to achieve the objectives of this study, a literature survey was conducted on bim uses, bim and software packages. quantitative research approach was adopted for this study. furthermore, the review of relevant literature resulted in formulation of a structured questionnaire based on 5-point likert-scale measurement. collins (2010) maintains that likert scales are effective to elicit participants’ opinions on various statements. questionnaires were administered to the relevant built environment professionals based in lagos, the commercial city of nigeria. the scope of this study was limited to lagos due its remarkable growth and demands for infrastructure development. a recent study revealed that the state has received huge investments over the years which includes; lekki free trade zone, eko atlantic city, dangote petroleum refinery, island international airport lekki and deep sea port (ogunde et al., 2017). out of one hundred and fifty (150) questionnaires were distributed, ninety (90) were completed and returned, and this resulted in a response rate of 60%. the response rate achieved in this survey provides reasonable data for analysis based on collins (2010). figure 7. research processes ibm spss version 23 and microsoft excel were used for data analysis. the study adopted descriptive (mean item score) and inferential (pearson correlation) statistics to analyze data obtained from respondents. mean item score (mis) was used to rank the awareness of bim uses. the variables were rated against a scale to assist in assessing the significance of each bim uses. the scale was then transformed into an average otherwise known as mean item score (mis) for each factor to determine the ranks of the different factors. it is represented mathematically below: 𝑀𝑀𝑀𝑀𝑀𝑀 = !"!#$""#%"##&"$#"% ("!#""#"##"$#"%) …………………………………………………………… (equation 1) literature survey 13 bim uses were identified 14 bim compliant software packages were identified questionnaire design and distribution the identified bim uses and software packages were used to design the questionnaire. questionnaire collection and data analysis data collected from questionnaires were subjected to mean item score (mis) and pearson correlation analysis presentation of result and discussion analysis results were presented in form of tables and charts 150 questionnaires were distributed and 90 were retrieved discussion of results was done by linking the findings of this study to existing literatures on bim journal of sustainable architecture and civil engineering 2020/2/27 70 questionnaires were administered to the relevant built environment professionals based in lagos, the commercial city of nigeria. the scope of this study was limited to lagos due to its remarkable growth and demands for infrastructure development. a recent study revealed that the state has received huge investments over the years which includes; lekki free trade zone, eko atlantic city, dangote petroleum refinery, island international airport lekki and deep seaport (ogunde et al., 2017). out of one hundred and fifty (150) questionnaires were distributed, ninety (90) were completed and returned, and this resulted in a response rate of 60%. the response rate achieved in this survey provides reasonable data for analysis based on collins (2010). ibm spss version 23 and microsoft excel were used for data analysis. the study adopted a descriptive (mean item score) and inferential (pearson correlation) statistics to analyse data obtained from respondents. mean item score (mis) was used to rank the awareness of analyse bim uses. the variables were rated against a scale to assist in assessing the significance of each bim uses. the scale was then transformed into an average otherwise known as mean item score (mis) for each factor to determine the ranks of the different factors. it is represented mathematically below: methods the research process for this study is divided into four distinctive processes namely; literature survey, questionnaire design and distribution, questionnaire collection and data analysis, and presentation of result as shown in figure 1. similar approach was adopted in olanrewaju and okorie (2019) for dividing research into stages. to achieve the objectives of this study, a literature survey was conducted on bim uses, bim and software packages. quantitative research approach was adopted for this study. furthermore, the review of relevant literature resulted in formulation of a structured questionnaire based on 5-point likert-scale measurement. collins (2010) maintains that likert scales are effective to elicit participants’ opinions on various statements. questionnaires were administered to the relevant built environment professionals based in lagos, the commercial city of nigeria. the scope of this study was limited to lagos due its remarkable growth and demands for infrastructure development. a recent study revealed that the state has received huge investments over the years which includes; lekki free trade zone, eko atlantic city, dangote petroleum refinery, island international airport lekki and deep sea port (ogunde et al., 2017). out of one hundred and fifty (150) questionnaires were distributed, ninety (90) were completed and returned, and this resulted in a response rate of 60%. the response rate achieved in this survey provides reasonable data for analysis based on collins (2010). figure 1. research processes ibm spss version 23 and microsoft excel were used for data analysis. the study adopted descriptive (mean item score) and inferential (pearson correlation) statistics to analyze data obtained from respondents. mean item score (mis) was used to rank the awareness of bim uses. the variables were rated against a scale to assist in assessing the significance of each bim uses. the scale was then transformed into an average otherwise known as mean item score (mis) for each factor to determine the ranks of the different factors. it is represented mathematically below: 𝑀𝑀𝑀𝑀𝑀𝑀 = %&'()&*(+&,(-&.(&/ (&'(&*(&,(&.(&/) …………………………………………………………… (equation 1) literature survey 13 bim uses were identified 14 bim compliant software packages were identified questionnaire design and distribution the identified bim uses and software packages were used to design the questionnaire. questionnaire collection and data analysis data collected from questionnaires were subjected to mean item score (mis) and pearson correlation analysis presentation of result and discussion analysis results were presented in form of tables and charts 150 questionnaires were distributed and 90 were retrieved discussion of results was done by linking the findings of this study to existing literatures on bim (1) scale mis decision/remark 5 4.50 to 5.00 highly aware 4 3.50 to 4.49 aware 3 2.50 to 3.49 neutral 2 1.50 to 2.49 less aware 1 0.00 to 1.49 not aware results and discussions where; n1= number of respondent(s) for ‘not aware’, n2= number of respondent(s) for ‘less aware’, n3= number of respondent(s) for ‘neutral’, n4= number of respondent(s) for ‘aware’ and n5= number of respondent(s) for ‘highly aware. table 2 shows the decision rule for mis. table 2. decision rule for mis scale mis decision/remark 5 4.50 to 5.00 highly aware 4 3.50 to 4.49 aware 3 2.50 to 3.49 neutral 2 1.50 to 2.49 less aware 1 0.00 to 1.49 not aware source: morenikeji (2006) correlation is a statistical measure that describes the degree or level of relationship between two variables. it was used to determine the strength of relationship between the building stages of bim uses. this is based on the decision rules given below: • rule 1: if p value > 0.05; then there is no significant relationship. • rule 2: if p value < 0.05; then there is significant relationship. the general formula is given below as: 𝑟𝑟 = 34567 (45)(48) √[345.7(45).][346. 7(46).] …………………………………………(equation 2) where; r = pearson correlation, n= number of data, ʃxy =sum of product of x and y, ʃx = sum of x, ʃy = sum of y, ʃx2 = sum of squared x and ʃy2 = sum of squared y. results and discussions characteristics of respondents the characteristics of the respondents were categorized using the gender, profession, academic qualification, working experience and type of practice. figure 2 shows that 80% were male while 20% female. figure 3 shows the profession of the respondents, 24% were quantity surveyors having a majority, followed by builders and civil engineers with 20%, following closely by architects with 19% and estate surveyors with 17%. figure 4 shows the academic qualification of the respondents, 1% of the respondents were doctorate degree holders, 40% had bachelor’s degree, 34% higher national diploma holders, 22% were master’s degree holders, and 3% were national diploma holders. figure 5 shows the working experience of the respondents, 40% of the respondents have 5-10 years of working experience, 32% had less than 5 years working experience, 12% had 11-15 years, 10% had 16-20 years with the lowest being 21 years and above having 6%. (2) where; n1= number of respondent(s) for ‘not aware’, n2= number of respondent(s) for ‘less aware’, n3= number of respondent(s) for ‘neutral’, n4= number of respondent(s) for ‘aware’ and n5= number of respondent(s) for ‘highly aware. table 2 shows the decision rule for mis. table 2 decision rule for mis source: morenikeji (2006). correlation is a statistical measure that describes the degree or level of relationship between two variables. it was used to determine the strength of the relationship between the building stages of bim uses. this is based on the decision rules given below: _ rule 1: if p-value > 0.05; then there is no significant relationship. _ rule 2: if p-value < 0.05; then there is significant relationship. the general formula is given below as: where; r = pearson correlation, n= number of data, ∑xy = sum of product of x and y, ∑x = sum of x, ∑y = sum of y, ∑x2 = sum of squared x and ∑y2 = sum of squared y. characteristics of respondents the characteristics of the respondents were categorized using the gender, profession, academic qualification, working experience and type of practice. fig. 8 shows that 80% were male while 20% female. fig. 9 shows the profession of the respondents, 24% were quantity surveyors having a majority, followed by builders and civil engineers with 20%, following closely by architects with 19% and estate surveyors with 17%. fig. 10 shows the academic qualification of the respondents, 1% of the respondents were doctorate degree holders, 40% had bachelor’s degree, 34% higher national diploma holders, 22% were master’s degree holders, and 3% were national diploma holders. fig. 11 shows the working expe71 journal of sustainable architecture and civil engineering 2020/2/27 rience of the respondents, 40% of the respondents have 5-10 years of working experience, 32% had less than 5 years working experience, 12% had 11-15 years, 10% had 16-20 years with the lowest being 21 years and above having 6%. awareness level of bim uses in the nigerian construction industry table 3 shows thirteen (13) bim uses categorized into three stages of building construction (design stage, construction / building stage, and operation / facility management stage). under design stage, seven (7) bim uses were identified with mean score ranging between 2.800 and 3.322. these bim uses at design stage ranged from cost estimation to sequencing which is the least ranged. to get the bim use respondents are very much aware of at the design stage, a mean score threshold of 3.000 was set. as a result, only six (6) bim uses were above 3.000 and considered significant. these bim uses are: cost estimation (mean = 3.322; sd = 1.069; t = -1.578; α = 0.872), construction planning (mean = 3.311; sd = 1.056; t = -1.697; α = 0.875), 3d coordination (mean = 3.144; sd = 1.250; t = -2.698; α = 0.872), prefabrication (mean = 3.067; sd = 1.216; t = -3.381; α = 0.870), visualization (mean = 3.044; sd = 1.090; t = -3.963; α = 0.877), and constructability analysis (mean = 3.022; sd = 1.196; t = -3.766; α = 0.868). under construction / building stage, three (3) bim uses were identified with a mean score ranging between 2.789 and 3.033. bim uses at construction/building stage ranged from construction monitoring to fabrication which is the least ranged. to get the bim use respondents are very much aware of at the construction/building stage, a mean score threshold of 3.000 was also set. as a result, only one (1) bim use was above 3.000 and considered significant. this bim use is construction monitoring (mean = 3.033; sd = 1.106; t = -4.002; α = 0.872). under operation / facility management stage, three (3) bim uses were identified with a mean score ranging between 2.489 and 2.900. bim uses at operation/facility management stage ranged from asset management to record modelling which is the least ranged. to get the figure 2. gender figure 3. profession figure 4. academic qualification figure 5. working experience awareness level of bim uses in the nigerian construction industry table 3 shows thirteen (13) bim uses categorized into three stages of building construction (design stage, construction / building stage, and operation / facility management stage). under design stage, seven (7) bim uses were identified with mean score ranging between 2.800 and 3.322. these bim uses at design stage ranged from cost estimation to sequencing which is the least ranged. to get the bim use respondents are very much aware of at the design stage, a mean score threshold of 3.000 was set. as a result, only six (6) bim uses were above 3.000 and considered significant. these bim uses are: cost estimation (mean = 3.322; sd = 1.069; t = -1.578; ∝ = 0.872), construction planning (mean = 3.311; sd = 1.056; t = -1.697; ∝ = 0.875), 3d coordination (mean = 3.144; sd = 1.250; t = -2.698; ∝ = 0.872), prefabrication (mean = 3.067; sd = 1.216; t = -3.381; ∝ = 0.870), visualization (mean = 3.044; sd = 1.090; t = -3.963; ∝ = 0.877), and constructability analysis (mean = 3.022; sd = 1.196; t = -3.766; ∝ = 0.868). under construction / building stage, three (3) bim uses were identified with mean score ranging between 2.789 and 3.033. these bim uses at construction / building stage ranged from construction monitoring to fabrication which is the least ranged. to get the bim use respondents are very much aware of at the construction / building stage, a mean score threshold of 3.000 was also set. as a result, only one female 20% male 80% quantity surveyor 24% architect 19% estate surveyor 17% builder 20% civil engineer 20% ordinary national diploma 3% higher national diploma 34% bachelor degree 40% masters degree 22% doctorate degree 1% less than 5 years 32% 5-10 years 40% 11-15 years 12% 16-20 years 10% 21 and above years 6% figure 2. gender figure 3. profession figure 4. academic qualification figure 5. working experience awareness level of bim uses in the nigerian construction industry table 3 shows thirteen (13) bim uses categorized into three stages of building construction (design stage, construction / building stage, and operation / facility management stage). under design stage, seven (7) bim uses were identified with mean score ranging between 2.800 and 3.322. these bim uses at design stage ranged from cost estimation to sequencing which is the least ranged. to get the bim use respondents are very much aware of at the design stage, a mean score threshold of 3.000 was set. as a result, only six (6) bim uses were above 3.000 and considered significant. these bim uses are: cost estimation (mean = 3.322; sd = 1.069; t = -1.578; ∝ = 0.872), construction planning (mean = 3.311; sd = 1.056; t = -1.697; ∝ = 0.875), 3d coordination (mean = 3.144; sd = 1.250; t = -2.698; ∝ = 0.872), prefabrication (mean = 3.067; sd = 1.216; t = -3.381; ∝ = 0.870), visualization (mean = 3.044; sd = 1.090; t = -3.963; ∝ = 0.877), and constructability analysis (mean = 3.022; sd = 1.196; t = -3.766; ∝ = 0.868). under construction / building stage, three (3) bim uses were identified with mean score ranging between 2.789 and 3.033. these bim uses at construction / building stage ranged from construction monitoring to fabrication which is the least ranged. to get the bim use respondents are very much aware of at the construction / building stage, a mean score threshold of 3.000 was also set. as a result, only one female 20% male 80% quantity surveyor 24% architect 19% estate surveyor 17% builder 20% civil engineer 20% ordinary national diploma 3% higher national diploma 34% bachelor degree 40% masters degree 22% doctorate degree 1% less than 5 years 32% 5-10 years 40% 11-15 years 12% 16-20 years 10% 21 and above years 6% figure 2. gender figure 3. profession figure 4. academic qualification figure 5. working experience awareness level of bim uses in the nigerian construction industry table 3 shows thirteen (13) bim uses categorized into three stages of building construction (design stage, construction / building stage, and operation / facility management stage). under design stage, seven (7) bim uses were identified with mean score ranging between 2.800 and 3.322. these bim uses at design stage ranged from cost estimation to sequencing which is the least ranged. to get the bim use respondents are very much aware of at the design stage, a mean score threshold of 3.000 was set. as a result, only six (6) bim uses were above 3.000 and considered significant. these bim uses are: cost estimation (mean = 3.322; sd = 1.069; t = -1.578; ∝ = 0.872), construction planning (mean = 3.311; sd = 1.056; t = -1.697; ∝ = 0.875), 3d coordination (mean = 3.144; sd = 1.250; t = -2.698; ∝ = 0.872), prefabrication (mean = 3.067; sd = 1.216; t = -3.381; ∝ = 0.870), visualization (mean = 3.044; sd = 1.090; t = -3.963; ∝ = 0.877), and constructability analysis (mean = 3.022; sd = 1.196; t = -3.766; ∝ = 0.868). under construction / building stage, three (3) bim uses were identified with mean score ranging between 2.789 and 3.033. these bim uses at construction / building stage ranged from construction monitoring to fabrication which is the least ranged. to get the bim use respondents are very much aware of at the construction / building stage, a mean score threshold of 3.000 was also set. as a result, only one female 20% male 80% quantity surveyor 24% architect 19% estate surveyor 17% builder 20% civil engineer 20% ordinary national diploma 3% higher national diploma 34% bachelor degree 40% masters degree 22% doctorate degree 1% less than 5 years 32% 5-10 years 40% 11-15 years 12% 16-20 years 10% 21 and above years 6% figure 2. gender figure 3. profession figure 4. academic qualification figure 5. working experience awareness level of bim uses in the nigerian construction industry table 3 shows thirteen (13) bim uses categorized into three stages of building construction (design stage, construction / building stage, and operation / facility management stage). under design stage, seven (7) bim uses were identified with mean score ranging between 2.800 and 3.322. these bim uses at design stage ranged from cost estimation to sequencing which is the least ranged. to get the bim use respondents are very much aware of at the design stage, a mean score threshold of 3.000 was set. as a result, only six (6) bim uses were above 3.000 and considered significant. these bim uses are: cost estimation (mean = 3.322; sd = 1.069; t = -1.578; ∝ = 0.872), construction planning (mean = 3.311; sd = 1.056; t = -1.697; ∝ = 0.875), 3d coordination (mean = 3.144; sd = 1.250; t = -2.698; ∝ = 0.872), prefabrication (mean = 3.067; sd = 1.216; t = -3.381; ∝ = 0.870), visualization (mean = 3.044; sd = 1.090; t = -3.963; ∝ = 0.877), and constructability analysis (mean = 3.022; sd = 1.196; t = -3.766; ∝ = 0.868). under construction / building stage, three (3) bim uses were identified with mean score ranging between 2.789 and 3.033. these bim uses at construction / building stage ranged from construction monitoring to fabrication which is the least ranged. to get the bim use respondents are very much aware of at the construction / building stage, a mean score threshold of 3.000 was also set. as a result, only one female 20% male 80% quantity surveyor 24% architect 19% estate surveyor 17% builder 20% civil engineer 20% ordinary national diploma 3% higher national diploma 34% bachelor degree 40% masters degree 22% doctorate degree 1% less than 5 years 32% 5-10 years 40% 11-15 years 12% 16-20 years 10% 21 and above years 6% fig. 8 gender fig. 9 profession fig. 10 academic qualification fig. 11 working experience journal of sustainable architecture and civil engineering 2020/2/27 72 bim use respondents are very much aware of at the construction/building stage using the same mean threshold previously used, no bim use at the operation/facility management stage was above 3.000. this indicates that majority of the respondents are not very much aware of the use of bim at the operation/facility management stage. table 3 awareness of bim uses s/n variables mean sd t-value α p-value r design stage 1 cost estimation 3.322 1.069 -1.578 0.872 0.118 1 2 construction planning 3.311 1.056 -1.697 0.875 0.093 2 3 3d coordination 3.144 1.250 -2.698 0.872 0.008 3 4 prefabrication 3.067 1.216 -3.381 0.870 0.001 4 5 visualization 3.044 1.090 -3.963 0.877 0.000 5 6 constructability analysis 3.022 1.196 -3.766 0.868 0.000 6 7 sequencing 2.800 1.083 -6.131 0.872 0.000 7 construction / building stage 8 construction monitoring 3.033 1.106 -4.002 0.872 0.000 1 9 maintenance scheduling 2.967 0.930 -5.443 0.875 0.000 2 10 fabrication 2.789 1.107 -6.096 0.868 0.000 3 operation / facility management stage 11 asset management 2.900 1.112 24.735 0.888 0.000 1 12 building system analysis 2.589 1.059 -8.163 0.883 0.000 2 13 record modelling 2.489 1.008 -9.513 0.881 0.000 3 sd = standard deviation; r = rank; α = cronbach’s alpha. correlation analysis was used to show the relationship between the awareness levels at different stages of a building as shown in table 4. the results from the correlation analysis show that there is a strong and significant relationship between the level of awareness at the design stage and construction stage (r = .647, p < .001). there is a weak but significant relationship between the level of awareness at the design stage and operation/facility management stage (r = .301, p = .004). lastly, it was revealed that there is a fairly strong relationship between construction/building stage and operation/facility management stage (r = .509, p < .001). table 4 correlation matrix for bim awareness at different stages of a building **. correlation is significant at the 0.01 level (2-tailed). stages 1 2 3 1 design stage 1 2 construction / building stage .647** 1 3 operation / facility management stage .301** .509** 1 73 journal of sustainable architecture and civil engineering 2020/2/27 fig. 12 shows the model for bim uses awareness at different stages of a building in nigeria. it is evident that the awareness level is only high at the design stage. this result validated previous researches by thurairajah and goucher (2013); raphael and priyanka (2014); wu et al. (2014a); wu et al. (2014b); and sunil et al. (2017) where it was stated that most of bim related developments are in the pre-construction area of cost management. fig. 12 model for current bim uses and awareness at different stages of a building in nigeria figure 7. bim compliant software usage and awareness conclusions this study has presented results of a questionnaire survey with the main aim to ascertain the current state of bim in the nigerian construction industry. the analysis revealed that bim is central to successful management of construction project but most stakeholders in nigeria are not aware of it uses at the operation / facility management stage of a building. it is also evident from the results that bim awareness level is only high at the design stage of a building. the study also modelled the current state of bim in the nigerian construction industry indicating the level awareness of each bim uses. most construction professionals are not very much aware of the use of bim for sequencing, maintenance schedule, fabrication, asset management, building system analysis, and record modelling. furthermore, this study revealed the commonly used bim compliant software packages in the nigerian construction industry to be: autodesk quantity takeoff, revit architecture, and sketchup. it is evident that the use of bimcompliant software in the nigerian construction industry is poor as most built environment professionals such as architects use it to compile layouts, develop architectural plans, and design conceptual elements. the study generated a number of practical implications which maybe applicable to other developing countries. firstly, it created a road map for nigerian construction industry stakeholders on the areas of bim usage. this would be of great benefit as regards policy formulation for bim and as well make stakeholders be aware of the areas that require considerable attention for bim to be fully implemented in the nigerian construction industry. secondly, the output of this research will also be useful to the academicians as it would aid the effective and efficient development of academic syllabus for built environment courses to include the areas of bim usage with low level of awareness. research limitations and future directions regardless of the findings of this research, it still has some potential shortfalls. the sample size was relatively small and the geographical area covered is small which may affect the generalization of the research. future research may consider wide geographical area which can cover all or major states in fig. 13 bim compliant software usage and awareness bim compliant software usage and awareness in the nigerian construction industry fig. 13 shows the bim compliant software usage and awareness in the nigerian construction industry. fourteen (14) bim compliant software packages were identified from the literature. 75% of the respondents were aware of revit architecture while 65% use it, 92% were of bentley bim suite while 12% use it, 86% were aware of archicad while 36% use it, 85% were aware of sketchup while 59% use it, 92% were aware of navisworks manage while 56% use it, 90% were aware of autodesk quantity takeoff while 69% use it, and 90% were aware of qs cad while 25% use it. furthermore, 42% were aware of tekla structures while 17% use it, 38% were aware of vico software while 9% use it, 48% were aware of archifm while 37% use it, 8% were aware of green building studio while 2% use it, 10% were aware of digital project while 1% use it, 69% were aware of masterbill while 21% use it, and 75% were aware of powercivil while 19% use it. on average, it can be deduced that the majority of the respondents are aware of bim compliant softand sunil et al. (2017) where it was stated that most of bim related developments are in the preconstruction area of cost management. figure 12. model for current bim uses and awareness at different stages of a building in nigeria bim compliant software usage and awareness in the nigerian construction industry figure 13 shows the bim compliant software usage and awareness in the nigerian construction industry. fourteen (14) bim compliant software packages were identified from literature. 75% of the respondents were aware of revit architecture while 65% use it, 92% were of bentley bim suite while 12% use it, 86% were aware of archicad while 36% use it, 85% were aware of sketchup while 59% use it, 92% were aware of navisworks manage while 56% use it, 90% were aware of autodesk quantity takeoff while 69% use it, and 90% were aware of qs cad while 25% use it. furthermore, 42% were aware of tekla structures while 17% use it, 38% were aware of vico software while 9% use it, 48% were aware of archifm while 37% use it, 8% were aware of green building studio while 2% use it, 10% were aware of digital project while 1% use it, 69% were aware of masterbill while 21% use it, and 75% were aware of powercivil while 19% use it. on average, it can be deduced that majority of the respondents are aware of bim compliant software packages but cannot purchase it due to its high cost. also, the technicalities of bim compliant software packages and inadequate personnel training has also prevented most professionals in the nigerian construction industry from using bim compliant software packages. the commonly used software packages were autodesk quantity takeoff, revit architecture, and sketchup. these software packages were also identified in previous researches (dare-abelet al., 2014; ibem and laryea, 2014; and al-matarneh and fethi, 2017) as cad tools that allow architects to develop architectural plans, compile layouts, and design conceptual elements and present complete design drawings on the computer before presentation to the clients (ibem et al., 2018). nigerian construction industry design stage construction / building stage operation / facility management stage cost estimation construction planning 3d coordination prefabrication visualization constructability analysis sequencing construction monitoring maintenance scheduling fabrication asset management building system analysis record modellinglow level of awareness high level of awareness legend bim building construction stages bim uses journal of sustainable architecture and civil engineering 2020/2/27 74 conclusions ware packages but cannot purchase it due to its high cost. also, the technicalities of bim compliant software packages and inadequate personnel training has prevented most professionals in the nigerian construction industry from using bim compliant software packages. the commonly used software packages were autodesk quantity takeoff, revit architecture, and sketchup. these software packages were also identified in previous researches (dare-abelet al., 2014; ibem and laryea, 2014; and al-matarneh and fethi, 2017) as cad tools that allow architects to develop architectural plans, compile layouts, and design conceptual elements and present complete design drawings on the computer before presentation to the clients (ibem et al., 2018). this study has presented the results of a questionnaire survey with the main aim to ascertain the current state of bim in the nigerian construction industry. the analysis revealed that bim is central to the successful management of construction project but most stakeholders in nigeria are not aware of it uses at the operation/facility management stage of a building. it is also evident from the results that bim awareness level is only high at the design stage of a building. the study also modelled the current state of bim in the nigerian construction industry indicating the evel of awareness of each bim uses. most construction professionals are not very much aware of the use of bim for sequencing, maintenance schedule, fabrication, asset management, building system analysis, and record modelling. furthermore, this study revealed the commonly used bim compliant software packages in the nigerian construction industry to be: autodesk quantity takeoff, revit architecture, and sketchup. the use of bim-compliant software in the nigerian construction industry is poor as most built environment professionals such as architects use it to compile layouts, develop architectural plans, and design conceptual elements. the study generated several practical implications which may apply to other developing countries. firstly, it created a road map for nigerian construction industry stakeholders on the areas of bim usage. this would be of great benefit as regards policy formulation for bim and as well make stakeholders aware of the areas that require considerable attention for bim to be fully implemented in the nigerian construction industry. secondly, the output of this research will also be useful to the academicians as it would aid the effective and efficient development of academic syllabus for built environment courses to include the areas of bim usage with the low level of awareness. research limitations and future directions regardless of the findings of this research, it still has some potential shortfalls. the sample size was relatively small and the geographical area covered is small which may affect the generalization of the research. future research may consider a wide geographical area which can cover all or major states in nigeria. another limitation of this study is the number of bim compliant software and usage considered. a further study may include more bim compliant software and usage not included in this study. recommendation the following recommendations were suggested: _ stakeholders education: stakeholders of the construction industry should be educated on how to use bim compliant software packages throughout the life cycle of a building and its benefits; _ openness to new technologies: stakeholders of the construction industry should be open to adopting new construction technologies which will increase the productivity of construction works; _ investment in bim research: government should invest heavily on bim-related research to enhance the body of knowledge on bim in nigeria and develop a suitable framework for bim implementation; and _ policy development: government should enact policies that will encourage the implementation of bim in nigeria. 75 journal of sustainable architecture and civil engineering 2020/2/27 references acknowledgement this research study was supported by the research funding of dollahills research lab, dollasoft technologies. the authors appreciate the reviewers for their valuable comments and suggestions towards improving the initial and subsequent drafts of this paper. adelekan, i. 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(eds), proceedings of the 12th international conference on computing in civil and building engineering (icccbe xii) & 2008 international conference on information technology in construction (incite 2008), 16th-18th october 2008, beijing, china. this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 19 journal of sustainable architecture and civil engineering 2022/1/30 *corresponding author: achernila@gmail.com the issue of post-industrial brownfields in piraeus, greece: suggesting international best practices in the era of globalization received 2021/12/22 accepted after revision 2022/02/11 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 19-31 doi 10.5755/j01.sace.30.1.30375 the issue of postindustrial brownfields in piraeus, greece: suggesting international best practices in the era of globalization jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.30375 abigail chernila fulbright research grantee to greece in partnership with the university of west attica, school of civil engineering tousi evgenia dr. architect-urban and regional planner ntua, adjunct lecturer, university of west attica, department of interior architecture introduction abstract piraeus, greece’s capital port city since the ancient times, is now home to many abandoned industrial sites that present an opportunity for revitalization through regeneration. this article presents applications of brownfield regeneration policies from the united states environmental protection agency and the eu brodise program for the case of piraeus, greece. the paper includes a theoretical framework that introduces the historical patterns of development through globalization and changing economic systems that led to the presence of brownfield sites around the world. the research utilizes field work at major brownfield sites in piraeus including site visits and stakeholder interviews, alongside literature review. the ultimate goal of the article is to exemplify areas of proven brownfield regeneration success internationally that can be applied to future policies to support efficient, transparent, and sustainable regeneration projects in greece. keywords: brownfields, de-industrialization, policy, sustainability, urban regeneration. this paper presents a general overview of industrial brownfield sites around the port of piraeus in the capital of greece and makes suggestions for further development and improvement, taking into account international best practices. reflecting on the european and american brownfield regeneration experience, we highlight the brodise program from spain, italy, and portugal, to outline policies useful for initiating the regeneration process, alongside the us epa’s grant structure, to outline potential funding mechanisms in greece. additionally, we aim to use differences in the epa structure as a potential blueprint for brownfield policy in greece: the us takes a centralized approach towards brownfield management with funding, programs, and regional offices put in place by the epa. conversely, greece does not currently have a national-level policy on brownfields and typically follows a case-by-case strategy, with regeneration projects decided by political or municipal authorities (tousi and serraos, 2020). as a result, this paper highlights the current absence of policy in greece and provides examples of successful policies from the international experience for potential future application. journal of sustainable architecture and civil engineering 2022/1/30 20 the history of the area of piraeus dates back to the ancient times as a significant centre for maritime activities. during the ottoman period, piraeus lost its prominence and it was not until the liberation from the ottoman regime (1821) that piraeus regained its role as a major port. in 1833 athens became the capital of the new greek state and piraeus functioned as the capital’s central port. after the 19th century, piraeus became also a hub for manufacturing activity. according to literature, industrial activity in greece followed different patterns than in the traditional industrial centres of the global north. in particular, after wwii, urbanization procedures were not followed by analogous industrial growth. on the contrary, emphasis was placed on tourism and on the construction sector (lefebvre, 2007). the expansion of the tertiary sector during the 1980s is strongly connected to the decline of manufacturing activity in piraeus. thus, after the 1980s piraeus experienced rapid de-industrialization procedures that affected the physiognomy of the urban fabric. gradually, scattered brownfield sites emerged around the port and along pireos avenue. without a consistent legal framework and action taken on a case-by-case basis, some of the brownfield sites in piraeus have been repurposed. however, today the majority of brownfield land sits derelict. during the past ten years, cross-border economic transactions have altered the existing urban balance, affecting brownfield management in the area. the opening up of the local economy to foreign investors has led to the inauguration of a new era of economic activity, influencing the existing land uses. to facilitate these new transnational financial collaborations, the new master plan of piraeus includes regeneration proposals at some of the area’s significant brownfield sites. from this point of view, the paper tries to define the crucial issues related to industrial brownfields, focusing on suggestions for future development. taking into consideration international experience on brownfield management and regeneration, the paper attempts to suggest good practices from abroad that might provide suitable analogies for the case of piraeus. using key-categories of funding and r&d strategies, the paper presents useful planning tools derived from the european union’s policies and programs, in addition to practices of the american environmental protection agency. given the current urban planning policies in the area, this paper makes suggestions for incorporating sectoral focus on brownfield redevelopment. particularly, these policies revolve around the contemporary “plan for integrated urban development” of piraeus. this type of plan has been introduced to the greek legislation since 1999, following the general concept of sustainable development. it is linked to law ν. 2742/1999, and especially to article 12. using the three main pillars of sustainability, “society-environment and economy”, these plans are considered useful guidelines for municipalities and local authorities so as to implement strategic interventions in degraded enclaves. they recognise the opportunities and challenges of the areas and offer a multilevel socio-economic and geographical analysis of the selected area. funding for these interventions is offered by the european union’s espa program, which aims to improve urban living conditions. the plan of integrated urban development in piraeus proposes seven areas of intervention, using 15 action groups and 66 actions, according to pertinent sources panagiotakis (2016) and argyropoulos (2020). the seven enclaves selected for regeneration are located along the waterfront (mikrolimano, karaiskaki stadium, neo faliron, palataki, hellenic naval academy) and within the city’s core, peripheral to the center of piraeus (karava, maniatika, agios dionisios drapetsonas). the main goal of the plan is to transform piraeus into an international hub for business and tourism by increasing competitiveness and by supporting investments in research and innovation. this approach is strongly connected to the goals of blue economy where maritime activities are of high priority. nonetheless, the regulatory plan of athens (2014), provides an eminent role for piraeus as an international point of reference, strengthening the already existing port activities and offering connection to the airport by expansion of the blue metro line. furthermore, the plan recommends strategies for sustainable mobility, suggesting new pedestrian routes and a bike path around the municipality. in addition, green policies are proposed for existing buildings, such as 21 journal of sustainable architecture and civil engineering 2022/1/30 green roof tops and vertical gardens. moreover, the plan puts emphasis on cultural heritage with its focus on management of listed monuments: mostly neoclassical and post-industrial buildings that have fallen into disuse over time. we note that the plan does not include brownfields as one of the categories of intervention, rather, select brownfield sites are included as a part of the policies regarding the aforementioned listed monuments and estates along pireos avenue. last but not least, the social goals of the plan target reducing unemployment and extreme poverty in piraeus. fig. 1 the areas proposed for regeneration according to the “plan for integrated urban development” of piraeus, authors’ work methods in this context, this paper provides useful strategies derived from the international experience so as to better facilitate the plan’s goals to foster socio-spatial cohesion in piraeus. given the lack of consistent policy on brownfields in the area, future urban interventions might overlook specificities connected to brownfield rehabilitation and regeneration. thus, the paper puts in the forefront significant issues for further consideration and application. with the view to highlight different shades of the brownfield management issue, this paper seeks to draw attention to the specificities of the selected case studies relevant to the unique historical evolution and cultural heritage of piraeus, making proposals for future application. the methods used during the research comprise of both field work and literature review. this field work has included visits to relevant sites throughout piraeus to record contemporary conditions, interviews with relevant stakeholders, and studies of the varying states of preservation. the authors have visited numerous scattered post-industrial facilities located in the regional administrative area of piraeus: already re-generated brownfield sites, key business hubs, museums, administrative buildings, derelict refuge housing, cultural hubs, and transportation centers. the authors have also conducted 20 semi-structured interviews on living conditions with relevant stakeholders in the area including students and professors, local residents, civil servants, and small business owners. this research has taken place in a preliminary period from 2018-2019 and has been updated and upgraded in the current academic year of 2021-2022. this work represents the first conclusions and results of ongoing quantitative research gathering data on desired land uses at current brownfield sites, which will be completed by may 2022. findings from authors prior research have also been evaluated so as to adumbrate the contemporary situation of piraeus’ brownfields. the authors have studied publications relevant to de-industrialization and brownfield redevelopment, focusing both on the impact of de-industrialization and on international best practices and strategies for post-industrial sites. moreover, the authors have delved into the case of piraeus in greece, so as to reveal the specificities of time and place which characterize the greek example. thus, the literature review includes publications that focus on the case of southern eujournal of sustainable architecture and civil engineering 2022/1/30 22 rope, greece, and in particular piraeus. furthermore, archival material from the greek ministry of public works has been studied so as to create cartographic depictions that illustrate the spatial distribution of industrial land uses in the regional administrative area of attica. theoretical framework about de-industrialization to analyse and interpret the nature and role of post-industrial brownfield sites, it is important to briefly review the international experience on the de-industrialization process. the phenomenon of de-industrialization is strongly associated with technological advancements in the manufacturing sector and globalization. according to saskia sassen (2005), after world war ii, new forms of economic transactions were observed, where key-financial institutions (insurance funds, nonbank corporations etc.) and the equities market play a nodal role crucial in the transformation of the urban economy in many areas around the world (ibid). this transition to the global market replaced the traditional fordist model and the so called “chain production”. according to sassen (2005) one of the key-aspects of de-industrialization is the increasing mobility of capital as a result of the improvement of information services. since the 1960s, accretive privatizations combined with cross-border economic transactions have altered traditional economic patterns. furthermore, the liberation of the headquarters from the location of manufacturing units altered existing balances: this affected the identity of metropolitan areas, as the re-location of manufacturing units overseas transformed the economic structure and organization of cities, thereby affecting the existing land uses and the social synthesis of the urban fabric. in this new socio-economic context, the role of metropolitan areas has severely changed. gradually, certain districts inside the city became strongly connected to the global market, accommodating international economic transactions. by acquiring an international architectural style and by changing the existing land uses, many metropolitan areas around the world became the global centres of today. examining new york, london and tokyo, the traditional centres analysed in sassen’s 2005 work, it is evident that their physiognomies have changed severely with globalization. in most cases, the opening up of local economies to the global market has evident spatial side-effects. the transformation of the existing land uses and the application of contemporary urban planning strategies are often linked to gentrification procedures. as described in vanessa’s watson work “the planned city sweeps the poor away”, the level of influence is strongly associated with pre-existing local conditions and local policies. (watson,2009). from this point of view, different cities experience the socio-spatial effects of globalization differently. however, the emergence of post-industrial brownfield sites created a challenge of worldwide significance: to find sustainable strategies to repurpose former industrial sites and facilities. brief overview of the international experience on de-industrialization according to international literature, there is a clear distinction between “positive” and “negative” de-industrialization (rowthorn and wells, 1987; clavijo et al., 2014). the first type refers to the shrinkage of industry because of the transition of former industrial workers into the service sector as a consequence of the new interrelations among different economic sectors; while the second focuses on the degradation of former industrial centres due to the emergence of new areas of strategic interest. in the first case, de-industrialization is perceived as a positive externality of successful urban development, with noticeable improvement on citizens’ living conditions. on the contrary, the second type of de-industrialization is linked to the re-location of manufacturing units, followed by job losses and often by long-term unemployment. such examples are found in the united kingdom with the cases of manchester and glasgow (schett, 2012). statistical data reveals that in 1913 manchester was an international centre for cotton production but by 1992 it lost 44,9% of its population due to the gradual reduction of the manufacturing activity (ibid). london on the other hand has managed to change its economic structure rapidly to keep up with the new forms 23 journal of sustainable architecture and civil engineering 2022/1/30 of economic transactions, leading it to be described as one of the first global cities of the world, alongside tokyo and new york (sassen, 2005). on the other side of the atlantic, areas like pennsylvania and ohio, which help make-up the “rust belt”, have experienced severe changes because of the de-industrialization process. significant job losses and population decline dramatically affected their physiognomy (fukuyama, 1999). however, other north american cities have achieved balance between former industrial growth and recent transnational changes by emphasizing opportunities for research and development. new york serves as an example of this path of development (leeman, 2007). the issue of post-industrial brownfields is significant for cities located in the global south as well. the rapid changes in china and the east asia pacific region towards new forms of services and new technologies have had a major impact on the organization and structure of urban areas. according to wang (2013), these alterations are responsible for the presence of a large number of brownfield sites in large and medium chinese cities. factories constructed during the period 19581961, known as the “great leap forward”, are now obsolete and derelict. according to pertinent literature, brownfield management and regeneration in asia is strongly informed by strategies employed in the global north; however, in practice this has often meant that specificities of time and place have been overlooked (roy and ong, 2011). this uptake of planning principles from the global north and the resulting standardization of forms and morphologies in brownfield regeneration in asian cities is further perpetuated by the frequent comparison of cities from both regions (roy and ong, 2011; watson, 2009). as wang (2013) notes, partial clean-up is common, which raises concerns for human health, further highlighting the need for public awareness and risk acceptance in the field of brownfield regeneration. in african cities, the management of industrial brownfield sites is connected with the confinement of urban sprawl and the overall upgrade of the surrounding areas, known as the co-location phenomenon (smith, 2010). the applied polices are incorporated into the framework for social and spatial cohesion following regeneration patterns from the usa and australia (van rooyen, 2001). in the former ussr countries, socio-political facets were a main driver behind the formation of brownfield sites. during the 1990s, political changes in the former ussr countries altered the prior manufacturing model, leaving many brownfield sites behind (schett, 2012). following these socio-political transformations, the fall of the berlin wall affected eastern german metropolitan areas, which experienced a sudden de-industrialization process. cities like leipzig and cologne previously contained many brownfield sites, however, today most have been repurposed, largely due to effective policies at the national level in germany (dixon and raco, 2007). it is important to mention that at the european union level, there is no single definition for a brownfield site: there are different approaches to the issue and a variety of sites with different scales and former uses (grimski et.al, 2001). since the losses in coal, steel, and textile manufacturing in the 1980s, many european cities have followed different brownfield management strategies to refurbish abandoned industrial sites (ibid). with the strategy of reinforcing compact urban forms, many countries like germany, the netherlands, and the uk focus on brownfield management in order to offer social and spatial cohesion in major metropolitan areas. across southern europe similar patterns of spontaneous industrial growth have shaped the physiognomy of cities. as globalization increased, localized production lost competitiveness leading to deindustrialization and high unemployment (gambarotto et al. 2019). while some of this deindustrialization can be attributed to costly changes required to adhere to european union policies upon becoming a member state, the eu does not have coordinated policies for governing industrial change or brownfield regeneration. as a result, eu countries have national-level approaches to brownfield policies at various levels of development and centralization. since greece’s industrial activities mainly supported textiles, apparel, and metal products, the country faced additional journal of sustainable architecture and civil engineering 2022/1/30 24 challenges with price competitiveness after adjusting to wto agreements (such as the multifibre arrangement in 1974 which allowed for quota restrictions on textiles) and after crowding out by eastern european and asian production of housing sector goods (gambarotto et al. 2019). today, lower domestic manufacturing in greece and higher presence of abandoned industrial sites, create a significant opportunity for brownfield regeneration. results and discussion policies on industrial brownfields: lessons from the international experience revitalizing brownfield sites in greece is a key policy initiative set by the european commission. the commission sees a lack of urban green space for the country’s residents and notes challenges in the preservation of coastal and marine areas. according to the european commission’s 2019 environmental implementation review for greece, the challenges currently accompanying brownfield regeneration are due to the following factors: “(i) a high concentration of human activity and land use; (ii) a lack of political will; (iii) no comprehensive planning for the preservation and management of these areas; (iv) inadequate control mechanisms; and (v) a lack of coordination between the relevant authorities.” liddle (2009) has also recognized significant levels of clientelism that obstruct regeneration efforts, despite eu driven efforts on culture, tourism, and agriculture. the european commission’s september and june 2021 enhanced surveillance report outlined a suggestion for greece to develop an integrated geospatial data mapping tool by year end-2021, as detailed below: 1. develop a state infrastructures registry to encapsulate technical and geospatial information about all public infrastructure projects to enable better planning and management of these projects, including for construction and maintenance purposes 2. develop an integrated geospatial data mapping tool (single digital map) to increase transparency to investors concerning land use rules across greece and reduce unpredictability in relation to investment licensing decisions the creation of this single digital map would centralize data on land ownership, occupancy, and contamination, which is expected to help reduce current unpredictability on licensing for real estate investments. while measures to reach this goal were still not in place as of 3q2021, under greece’s recovery and resilience plan the country is targeting a contract awarded for creation of a unified digital map by 4q2022. policies and expertise from the european union: brodise program the brownfield decontamination in southern europe (brodise) program was an eu-level initiative in 2015 that focused on public and private collaboration for soil decontamination and brownfield regeneration in bilbao, spain, sexial, portugal, and trieste, italy. the project developed a common conceptual model for standard data collection at brownfield sties, utilized new technology for measuring soil contamination, developed a pre-commercial procurement (pcp) procedure, and created an open dialogue for researchers, smes and companies that provide decontamination solutions. given that piraeus does not currently have a database that records the contamination present at its brownfield sites, we believe that the scenario system used in the brodise program would benefit parties interested in redevelopment. the brodise system has guidelines on how to measure and record contamination data at each site and offers various policy guidelines based on the desired use of each site, in order to lower the costs associated with regeneration (park, 2019). policies are broken into the following scenarios: 1. residential land use desired in presence of high concentration level of contaminants 2. mixed land use or parceling out desired based on presence of varying concentration levels of contaminants 3. industrial land use desired in presence of high concentration level of contaminants 25 journal of sustainable architecture and civil engineering 2022/1/30 this system of land use subdivision allows for remediation of higher cost zones only when residential use is desired or in the presence of high concentration levels of contaminants. this increases cost effectiveness, as less remediation is required when industrial use is desired or for land with lower known concentrations of contaminants. in regards to testing contamination present at various sites, the brodise methodology of 500 sq meter surface field tests with 100m minimum distance between test sites, may be applied in piraeus since there is not presently a uniform method to obtain or store this information. to achieve a balance of cost-savings and accuracy, only one test may be required where high pollution is known to be present, whereas multiple tests with the same results will be required to confirm contamination concentration at sites with unknown pollutant levels (bedin, 2019). in addition, applicable coring and water samples along with chemical analysis on soil and groundwater are necessary to determine the concentration of subterraneous contamination. this data combined with the land-geological-morphological data should then be used to develop a site sample that can analyze the environment and health risks from contamination at each site. we believe the pcp methodology proposed by the brodise program could also be applied to the case of piraeus to outline simultaneous research and development by different suppliers competing in different phases of development. this can enable simultaneous identification of the best value solutions, make use of competitive development, and ensure risk-benefit sharing of market conditions. the research and development schedule may include testing suppliers simultaneously for the following three phases: (1) solution, exploration, and technical design, (2) prototyping, and (3) field testing; with the final supplier chosen for each consecutively as follows: (1) most economically advantageous offer, (2) ability to best meet stakeholders’ needs, and (3) robustness at that unique site (bedin, 2019). to ensure fair competition, we uphold the brodise policy that the start of the tendering procedure should be published with a description of the scope, scale, and estimated value of the contracts in addition to application procedures both in the official journal of the eu and on the project websites (bedin, 2019). all submissions should be made public in order to prevent discrimination and the contracts should state the terms and conditions, deliverables expected, timeline, and financial payment schedule. the general financing guidelines of value-for-money, transparency, and ethics should also be maintained for the case of greece. these include selecting services that offer the maximum benefit for the cost and meet the requirements in the most cost-effective way, ensuring fair competition and non-discrimination in addition to record keeping for accountability, and prohibiting conflicts of interest. the brodise program offers a technical example for the soil testing, r&d, and pcp stages of a brownfield regeneration project that is in line with the standards and best practices of the european union. for the financing of case-by-case projects, we look to the funding mechanisms used in the united states. lessons from the united states environmental protection agency the environmental protection agency (epa) is an independent executive agency of the federal government of the united states that works to improve and protect environmental and human health outcomes. the epa writes national level regulations after congress passes an environmental law, and it enforces the national standards that it sets with regional offices around the us. while the administrative organization and structure of authorities of the epa differs from the institutional organization in greece, certain epa funding mechanisms for brownfield regeneration could be utilized in the case of piraeus. epa assessment grants provide funding for brownfield inventories, planning, environmental assessments, and community outreach. applied to the case of greece, this type of grant could supjournal of sustainable architecture and civil engineering 2022/1/30 26 port the creation and maintenance of a database in each municipality that maps out abandoned land and includes details on contamination present. the epa also has revolving loan fund grants which provide funding to capitalize loans that are used to clean up brownfield sites, along with cleanup grants that provide funding to carry out cleanup activities at brownfield sites owned by the applicant. these grants can be used on a site-by-site basis to support the funding of proposed regeneration projects. this type of funding may present an opportunity to prevent future brownfield sties as additional industrial sites become obsolete given shifts towards decarbonation: companies or current land owners could proactively use this funding to cleanup newly obsolete factories before the sites may reach more challenging levels of degradation. additionally, the epa offers multipurpose grants that provide funding to conduct a range of assessment and cleanup activities at one or more brownfield sites in a target area. in greece, a similar version of these grants may be created to provide funding for archaeological research at necessary brownfield sites. finally, a version of the epa’s job training grants, which provide environmental training for residents impacted by brownfield sites in their communities, may be created to increase local employment and training on reclamation of contaminated brownfield land. through this variety of grants, the us has seen success in brownfield regeneration at a local level, as municipal governments and residents are encouraged to collaborate on revitalization projects. we see this participatory urban planning method as key to the case of greece, due to high rates of home ownership and strong intergenerational community ties resulting in residents maintaining significant interest in their localities. focusing on the case of piraeus piraeus is the main port of athens and one of the most important ports of the mediterranean region. during the late 19th and the early 20th century, piraeus focused on industrial activity to such an extent that scholars describe the area as the “greek manchester” (kotea, 1995). the area has had a dynamic history since the ancient times, with archaeological findings suggesting that the area has been inhabited at least since the 26th century bc. piraeus experienced the prosperous times of the ancient golden era (5th and 4th century b.c.) and later became a part of the roman and byzantine empires. given the geographical distance between istanbul and athens, piraeus lost some of its pertinence during the byzantine era and gradually became degraded. following the liberation from the ottoman regime and the nomination of athens as the capital of the new greek state (1833), piraeus prevailed again as a focal point for the capital’s economic activity. the urban development of that time focused not only on maritime activities and trade but also on industrial production. moreover, the refugee inflow during the interwar period after the 1922 asia minor catastrophe, led to further development of the industrial activity in the area. according to literature (sarigiannis, 2000) there is an evident socio-spatial pattern regarding the location of the refugee settlements; in the urban periphery, near the existing industrial units. additionally, there are cases where new manufacturing units were erected after the refugee settlement (ibid). the refugees became the new force that fostered the ongoing industrial activity in the area, creating working class suburban neighborhoods all around central piraeus (tousi, 2014). unfortunately, wwii and the civil war, severely affected the development of piraeus. piraeus experienced heavy bombings that resulted in near-total destruction of the port area. the port of piraeus authority was responsible for returning the port to its pre-war form and modernizing both the port and the area of greater piraeus (hadjimanolakis, n.d.). after the 1960s, piraeus managed to recover from wwii damages and setbacks, with most manufacturing units remaining active. however, the excessive evolution of the tertiary sector during the 1980s and the 1990s altered the existing balances. according to pertinent literature, the majority of piraeus’ factories fell into disuse during this period (tousi and konstantinos, 2020). whereas manufacturing, light industry, and processing accounted for nearly 20% of the country’s gdp 27 journal of sustainable architecture and civil engineering 2022/1/30 fig. 2 location of industrial uses in the capital of greece, authors’ work fig. 3 location of industrial uses around piraeus port, authors’ work in the 1970s, by the mid2010s this sector accounted for less than 6% of gdp (kanoupakis, 2017). this is further demonstrated by a decrease in operation permits for manufacturing sites, with the country reporting 1,156 new permits granted and 739 permits extended in 2001 but only 302 new permits granted and 307 extended in 2015, according to the hellenic statistical authority. as a result of this shift away from manufacturing, many brownfield sites around piraeus port and in the greater piraeus region have appeared since the mid-1990s, which we depict in figures 2 and 3. during the last decade, the cooperation between piraeus port authority and the chinese firm cosco, has influenced the forthcoming regeneration projects. given that cosco has leased piers ii and iii for 35 years, urban development in the area will inevitably become connected with the company’s interests. on account of this, the new masterplan of piraeus includes regeneration proposals for some of the area’s most significant brownfield sites that today sit derelict (fig. 2). given the ancient past of the piraeus region, there are archaeological concerns at many sites (ibid). from this point of view, piraeus’ brownfields are strongly associated with issues of cultural management. consequentially, the presence of archaeological remains introduces a sizeable legal and administrative consideration for moving forward with future land uses. permission for state owned land must come from the archaeological service of the ministry of culture, which may be regionally handled by the local ephorate of antiquities or general directorates, which go through the central archaeological council for advising for decisions whether a land-use request may be accepted (hartzoulaki, 2019). additionally, outside of ancient archaeological considerations, some of these brownfield sites have been classified as listed architectural monuments, which requires that any regeneration at the site must maintain the original façade of the building (law 3028, 2002). the current heightened foreign interest in piraeus (following cosco’s 2016 investment) presents an economic opportunity for the municipality through tourism. the oecd found that only 16.5% of cruise ship passengers stay in piraeus, with the average expenditure per cruise visitor in piraeus rarely exceeding eur 20. due to the location of the cruise ports relative to the most attractive parts of piraeus, most passengers only pass through the area before commuting to the athens journal of sustainable architecture and civil engineering 2022/1/30 28 city center (oecd, 2017). while piraeus itself hosts an impressive archaeological museum and pedestrian streets with restaurants, shopping, and art galleries, the lack of hotels and public transportation options from the port present barriers to keeping visitors within the municipality. tourists often opt for private tour buses that skip over piraeus and head directly to athens, to circumvent the lack of translation and information on routes, stops, and schedules. the oecd also found that the immediate surroundings of the port further perpetuate the perception that piraeus is not an area to visit, but a pass-through city on the way to athens. improving tourism within piraeus can contribute to the local government’s goal of job creation to help the municipality’s high rate of youth unemployment. attica may also experience environmental benefits from keeping visitors in piraeus for longer, as it can help reduce hyper tourism in the center of athens, lower pollution and improve air quality, and prevent an intensifying urban heat island effect by reducing both the number of vehicles and individuals in the city center at any given time. given the current case-by-case strategy of brownfield regeneration, one-off regeneration projects have begun across the greater piraeus area. one such example is the new building complex at the papastratos tobacco industry in piraeus, which has created office facilities at the prior tobacco warehouses of the piraeus port plaza (asimakopoulou, 2021). progress has also been made at drapetzona, one of the listed monuments on the shore of peripheral area of piraeus. in recent years the seafront area below the prior industrial site has been transformed into a boardwalk, bike path, and café area, as shown in fig. 5 and fig. 6. this part of the larger brownfield site is well attended by local residents as it offers an outdoor meeting place with parking available. however, the majority of the land remains idle, given the need to maintain the façade of the prior factories onsite due to drapetzona’s chemicals and fertilizers factory’s classification as a listed architectural monument. overall, this case-by-case method differs broadly from the successful strategies from abroad, which further emphasizes the need for a centralized approach that includes surveying, cartographic depiction, assessment of current sites, and financial instruments mentioned. early results of authors’ ongoing surveys of residents and visitors in attica show a clear preference for regeneration projects that create public greenspaces at current brownfield sites. these include community gardens, parks, nature trails, and outdoor athletic fields. after preference for green space, stakeholders also expressed interest in transforming brownfields to host cultural sites, museums, galleries, and exhibition spaces. according to ongoing field work, citizens seem to converge to the importance of brownfield management, with some noting that there is a lack of consultation of the general public on these issues and little movement to begin regeneration processes. taking into consideration field work findings, the local community’s outlook on brownfield regeneration includes undoubtedly participatory forms of planning and design so as to enhance top-down policies with a bottom-up perspective. from this point of view, local residents’ vision for the future of drapetzona’s brownfield sites fig. 4 currently derelict building in piraeus to be transformed into a museum according to the new masterplan, authors’ field work 2021 29 journal of sustainable architecture and civil engineering 2022/1/30 fig. 5 the brownfield site of the chemicals and fertilizers factory in drapetzona before the regeneration of the waterfront, authors’ field work, 2019 fig. 6 the brownfield site of chemicals and fertilizers factory in drapetzona, regeneration of the waterfront and derelict post-industrial facilities, authors’ field work, 2021 ascribes high significance on the preservation of urban collective memory. according to the interviews, local residents propose solutions that combine industrial architectural monuments with land uses that cover their contemporary needs. policies that fail to incorporate citizens’ opinions would probably neglect a wide range of critical factors that affect the physiognomy of the area (low socio-economic strata, high unemployment rates, high population density, poor housing facilities, scarce landscaped outdoor spaces etc.). regeneration projects that facilitate a market driven approach have already been documented across the mediterranean region, as in the case of barcelona, presenting a tourism-led gentrification process (cocola-gant, et.al, 2020). to avoid this socio-spatial pattern in piraeus, local communities should be perceived as an important stakeholder in the planning process. the risk of creating urban spaces for visitors and investors could be counterbalanced by collaborative and inclusive forms of planning, so as to foster social cohesion in piraeus. conclusions deindustrialization has impacted economies and cities globally and will continue to do so as technology and environmental considerations continue to adapt. since the 1990s greece has experienced deindustrialization and increased reliance on imports, as evidenced by a nearly a 20% decrease in the use of domestic production to meet domestic demand compared to 1995 levels (kanoupakis, 2017). the urban landscape of deindustrialization in piraeus, while challenging in its current condition, presents opportunities for economic, environmental, and spatial benefits for residents. however, these opportunities will require an organized, centralized policy approach to address the area’s unique challenges. the current legislation is fragmented with small pieces of information scattered inside different laws on environmental specifications, military facilities, the attica regulatory plan, and the local general urban plan (tousi and konstantinos, 2020). journal of sustainable architecture and civil engineering 2022/1/30 30 references given the history and scale of deindustrialization in greece, the country would benefit from centralized brownfield-specific legislation with national standards for decontamination, licensing, coordination among authorities, and archaeological considerations to help streamline and add transparency to the regeneration process. as lefebvre (2007) describes, tourist consumption in areas surrounding athens’ monuments and sites along with disorganized new constructions around the city center, has created a cycle of economic reliance on tourism and the construction center in greece. this rapid form of expansion has created a network further perpetuated and maintained by the network of continued construction. given these specificities of the economic network in greece, which differs from those of the traditional industrial centers post de-industrialization, brownfield regeneration has the ability to help maintain both the shape of the city and the country’s unique economic model. the country should take into account the lessons from international experience on brownfields including eu-level suggestions for national digital cartographic depiction of sites, the brodise program’s pcp system, and the us epa’s funding options. while the case of piraeus presents unique challenges given archaeological findings, current lack of cartographic data, and fragmented legislation, once progress is made in these capacities the area has opportunity for significant benefits to the local community and economy given its strategic location. the municipality has the chance to define its history of deindustrialization as “positive”, by better utilizing both international economic interest and touristic opportunities in the area to increase employment and improve local facilities and conditions. with a more centralized approach towards brownfield management that takes local residents’ needs into account, alongside focus on marketing the already-present tourist attractions, we believe piraeus can shift from a pass-through point, to an innovative and green hub for both its current population and future visitors. acknowledgements this research is sponsored by the fulbright foundation in greece, with support from the university of west attica, department of civil engineering. argyropoulos, d., στρατηγικη μελετη περιβαλλοντικων επιπτωσεων (ς.μ.π.ε.) του ειδικου χωρικου σχεδιου (ε.χ.ς.) περιοχης αγιου διονυσιου δημου πειραιa. 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development. 46th isoca rp congress 2010, nairobi, kenya, 2010. tousi, evgenia and konstantinos, serraos. brownfield management in greece, the case of piraeus. journal of sustainable architecture and civil engineering, 2020. us epa. types of epa brownfield grant funding. us epa, 2020. van rooyen, ej, integrated development and the brownfield phe¬nomena, journal of public administration, 2001; 36(1): 61-80. wang q., brownfield remediation and redevelopment in china: legal and regulatory frameworks, processes and actions. graduate school of architecture, planning, and preservation columbia university, 2013. watson v., the planned city sweeps the poor away. urban plan¬ning and 21st century urbanisation. 2009; https://doi.org/10.1016/j.progress.2009.06.002 72(3): 151-193. this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). journal of sustainable architecture and civil engineering 2022/1/30 106 life cycle environmental and cost analysis of building insulated with hemp fibre compared to alternative conventional insulations – a swedish case study *corresponding author: skaev07@student.lnu.se life cycle environmental and cost analysis of building insulated with hemp fibre compared to alternative conventional insulations – a swedish case study received 2021/12/19 accepted after revision 2022/04/19 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 106-120 doi 10.5755/j01.sace.30.1.30357 jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.30357 mathilda hult, sara karlsmo linneaus university, faculty of technology department of building technology, universitetsplatsen 1, 352 52 växjö, sweden summary this study presents a comparative life cycle analysis (lca) and life cycle costing (lcc) assessments of hemp fibre and conventional alternative insulations for the climate shell of a building. the conventional alternative insulations compared to the hemp fibre are cellulose and glass wool. the object of the analysis is a one-story single-family house, in växjö, sweden, and the lifetime of the house is set to 50 years. the lca focuses on the global warming potential (gwp) impact and the lcc during the lifetime of the different insulations for the building are calculated using the net present value method. the results show that the net gwp-impact for hemp fibre insulation is about 10 % lower and the cost is about 20 % higher than the conventional glass wool alternative. furthermore, the analysis shows that cellulose insulation has slightly lower gwp-impact and nearly the same cost as the glass wool alternative. sensitivity analyses regarding five different issues were performed and these show that: for cellulose coming from recycled paper, it contributed to less fossil emissions than non-recycled paper. if the data source for glass wool insulation is changed from environmental product declarations (epd) to generic data, the greenhouse gas emissions increased. by replacing district heating system with geothermal heating system, fossil gwp-impacts also increased while the lcc analysis shows that operating costs is reduced. if the fuel is changed from diesel to electricity, fossil emissions are reduced over the life cycle of the building. if only part a1 – a5 is reported, as required for the swedish climate declaration, the results point to the outcomes that glass wool insulation gives the least fossil gwp-impact while the hemp fibre gives the least net gwp-impact. keywords: life cycle analysis, life cycle cost, climate impact, hemp fibre insulation, cellulose insulation, glass wool insulation, residential building. 107 journal of sustainable architecture and civil engineering 2022/1/30 with the growing concerns of climate changes, the paris agreement and the european union’s net emissions targets have influenced the building sector in sweden to become more climate neutral (european commission u.å.a; europeiska rådet 2021). according to the managing authority boverket (2021b), the building sector accounted for a fifth of sweden’s total greenhouse gas (ghg) emissions, in 2018. kosiński, brzyski, szewczyk & motacki (2018) and zampori, dotelli & vernelli (2013) claim that the choice of building materials has a significant effect on emissions of ghg. in addition to the building’s operational phase, the production of various building materials causes emissions of ghg, where the emissions vary greatly depending on the material (boverket 2021a; treloar, fay, ilozor & love 2001). to facilitate the choice of building materials with less climate impact, from 2022 onwards there will be requirements for a climate declaration in sweden (ministry of the environment 2020). increased environmental awareness and an increased interest in sustainable, ecological and renewable materials means that the use of more environmentally friendly insulation is expected to increase. this is supported by many studies and has led to an increased demand for industrial hemp in the world, especially in europe (kymäläinen & sjöberg 2008; kallakas, närep, närep, poltimäe & kers 2018; bouloc, allegret, & arnaud 2013). there are limited studies of hemp fibre as insulation material in the swedish context, which may be due to the fact that hemp fibre has been illegal to grow in sweden since the 1970s, but in 2003 certain plants can be approved for cultivation (kunglig majestäts kansli 1972). like the rest of the world, there is an interested in hemp fibre, especially in europe (bouloc, allergret & arnaud 2013). according to a study conducted by zampori, dotelli & vernelli (2013) in australia, hemp fibre insulations result in less emissions of co₂e compared to glass wool, for example. in addition to different climate impacts, insulation materials also have different costs, which can affect the choice of material (kymäläinen & sjöberg 2008). cellulose is another material which has had a small share in the insulation market, which might be due to limited knowledge of the material’s moisture absorption capacity (tumusiime, kirabira & mmusinguzi 2020; lopez hurtado, rouilly, vandenbossche & raynaud 2016). cellulose insulation is interesting to study as it exhibits low environmental impact (sohn et al. 2017). presently, the common insulation material in sweden is mineral wool, which has dominated the market in northen europe by representing 57 % of the market shares (sohn et al. 2017). there is an idea that purchase price can be a reason why conventional insulation maintains its market share (zabalza bribián, valero & aranda usón 2011). according to emblemsvåg (2003) the result of an lcc can justify environmental change. by calculating a building’s environmental impact with an lca and complementing this with a life cycle cost (lcc), a more comprehensive picture of the building’s climate impact and cost can be made visible and understood. as we enter a new epoch of great focus on what needs to be done for the good of the planet, the discussion should be about what is required when the decision itself is made. this study investigates which choice of insulation material is most environmentally friendly and what the choice of the most environmentally friendly material will cost in a life cycle perspective. this is a decision that we believe many individuals can face and is crucial for the selection of a sustainable building material. this study examines the environmental and economic consequences of the decision to choose between three different insulation materials for the construction of a single-family house in sweden. the purpose of the study is to provide more basis for the choice of insulation material looking into the climateand cost implication of hemp fibre, cellulose and glass wool insulation. case study house the insulation needed in a standard one-floor swedish single-family house is analysed to evaluate the implications of the different insulation materials, see figure 1. introduction journal of sustainable architecture and civil engineering 2022/1/30 108 fig. 1 an illustration of the house (a) and a drawing of the floorplan (b) (a) (b) table 1 wall thickness [mm], roof thickness [mm], gross floor area [m²], habitable area [m²], ceiling height [mm], roof slope [°] and u-value [w/( m²k)] house model building information hemp fibre cellulose glass wool wall thickness 375 350 345 roof thickness 227,7 224,7 224,2 gross floor area 176,8 175,3 175,0 habitable area 153,0 153,0 153,0 ceiling height 2500 2500 2500 roof slope 24 24 24 table 2 u-value [w/( m²k)] u-value of building components building component u-value slab 0.13 exterior wall 0.14 window 0.9 front door 1.3 front door 1.1 roof 0.07 methodology the construction consists of a wooden frame with a wooden facade. the design of the construction when calculating and modelling the building follows references for construction in sweden (svenskt trä 2014a; 2014b, 2015). in the study, the insulation material in the house are varied between hemp fibre, cellulose and glass wool. the different thermal conductivity of the insulation materials required that in some cases the wall thickness had to be altered to achieve the same u-value in the climate shell, see table 1 and 2. the study is dethe lca focused on the environmental consequences while the lcc highlighted the economic aspect of the insulations. lca the method used for the study was an attributional lca. this was carried out according to the normative standard sustainability of construction works evaluation of buildings’ environmental performance calculation method (ss-en 15978: 2011). in order to be able to compare, the functional unit was chosen to be kilograms of carbon dioxide equivalents per square meter of habitable limited by looking only at the house model’s climate screen. the house’s energy use follows swedish building code’s (bbr) requirements for energy use of detached houses located in växjö, sweden. the number of residents in the house is calculated as 4 people and thus the house’s heat recovery (ftx) ventilation and water use are calculated according to these conditions. in the study, the house is assumed to be heated with district heating (eriksson, hult & karlsmo 2021). 109 journal of sustainable architecture and civil engineering 2022/1/30 area [kg co2e / m 2 habitable area], as the habitable area do not change due to increased insulation volume. the goal of the lca was that the result should be able to facilitate the decision-making process for house manufacturers and house buyers. the system boundaries of the study are defined as follows: _ the examined materials were those that affects the u-value of the climate screen and eventually affected by a change in wall thickness. _ the study does not include stages that were similar for house models when using the different insulations. _ the environmental impact was limited to emissions of kilograms of co2e. _ the time horizon of the analysis was set to 50 years _ the study covers carbon flows in the following stages: product stage (a1 – a3) transport (a4), waste (a5), operating energy (b6), transport of waste (c2), waste management (c3), landfill (c4) and profits outside the system limit (d). further detailed regarding the study’s boundaries is found in eriksson, hult & karlsmo (2021). _ data on the insulation materials were obtained primarily from epds (type iii) produced for sweden and secondarily from generic data. the different building materials from epds did not have the same functional unit, therefor the data needed to be recalculated with a comparable unit. detailed regarding the study’s data are documented in eriksson, hult & karlsmo (2021). _ data on other materials were retrieved primarily for generic data and secondarily from epds. _ data were reviewed and evaluated based on the acquisition method (if the data was credible), age, geographical area, technology of production and method of verification (if the data was complete) in accordance with the methodology of pedersen weidema & suhr wesnæs (1996). _ in the study, the transports were limited to being calculated with generic data and data from epd in stage a4. in the remaining stages, the transports with a truck with a maximum load of 26.1 tonnes were calculated. _ emissions in stage a4a were calculated by multiplying the mass of the materials [kg] by the factor for a4 from the epd or the generic data. other transports were calculated with tons of material multiplied by the truck’s maximum weight and multiplied by the distance. per full truck, return only own weight. _ in phase c2, the transports were divided up so that certain materials could be recovered for energy through firing and others ended their life cycle as landfills. for more detailed boundaries see the bachelor thesis (eriksson, hult & karlsmo 2021). quantity calculation the materials which were taken in account are those within the system boundaries: wood, plaster, insulation in loose wool and board form, cellular plastic, concrete 30/37, reinforcement, osb boards, concrete boilers, baseboard, plastic film and windows and doors. to ensure data quality, pedersen weidema & suhr wesnæs’s (1996) procedure was followed. the operating phase (b6) was calculated in vip-energy (version 4) software. the building’s energy performance calculations were conducted in accordance with ss-en 15978 2011. vip-energy is validated according to: leed, breeam and ansi ashrae-140. calculation methods in the program for the one-dimensional and two-dimensional building components are valid according to the standard iso 10211:2007 (strusoft 2020). input data for vip-energy are presented in table 3. table 4 shows the different analyzes performed in the study, the sensitivity analyzes were done to examine the sensitivity of different parameters by changing key values and assumptions. journal of sustainable architecture and civil engineering 2022/1/30 110 input data description parameter input value comments climate climate data växjö (1981 – 2010) building location (kap. 3 objektbeskrivning in the study by: eriksson, hult & karlsmo 2021)) horizontal angle 20 ° to account for shading from nearby objects (dodoo, yao ayikoe tettey & gustavsson 2017; strusoft 2020) wind load that hit the building 70 % slightly protected from nearby surroundings (strusoft 2020) solar reflection against ground 20 % share of solar reflected from the ground into building (strusoft 2020) indoor temperature and heat gains lightning and appliance 2,06 w/m2 building empty mon-fri 7–16/weekends 9–15, other time 4 persons in the building (sveby 2012) persons 2,4 w/m2 80 w/person (sveby 2012) hot water 2,3 w/m2 standard (strusoft 2020) heating 30/21 °c highest/lowest (boverket u.å.) ventilation supply air 600 pa/ 55 % fan pressure/fan efficiency (strusoft 2020) exhaust air 500 pa/ 55 % fan pressure/fan efficiency (strusoft 2020) air change rate 0,35/0,1 l/sm2 building occupied/empty (bfs 2011:6) the analysis that was made why it was made sensitivity analysis: cellulose to investigate how the recycled raw material affects the result, the cellulose was chosen to be compared. new raw material in relation to recycled. sensitivity analysis: glass wool to investigate whether the type of input data affected the result, the glass wool insulation was replaced. from epd to the national board of housing, building and planning’s climate database. sensitivity analysis: heating system to investigate the sensitivity in the choice of the heating system, geothermal heat pump (which has a sharply rising popularity in sweden) was compared with district heating (common in växjö). sensitivity analysis: fuel as electric cars are advocated for being more environmentally friendly than diesel cars, a study was conducted to see how the choice of transport of materials affects a building’s total emissions. sensitivity analysis: biogenic carbon as the managing authority boverket (2021a) does not require biogenic carbon to be included in the climate declaration, an alternative climate declaration was developed without biogenic carbon in stages a1 – a5. to be set against a climate declaration where the biogenic carbon is included. the climate declaration includes: steps a1 – a3, a4 and waste from a5. lcc the lcc follows the same stages and system boundaries as the lca and is finally calculated according to the procurement authority’s general calculation. for comparison, the functional unit was chosen in swedish crowns per square meter of habitable area [sek / m2 habitable area]. the goal of the lcc was, like the lca, to be able to facilitate the decision-making process for home builders and home buyers. the prices were retrieved primarily from the bidcon database bidcon updates prices twice a year (consultec byggprogram ab u.å.). secondly (hemp and cellulose) from their retailers. table 3 input data for the parameters in energy calculation table 4 table of completed analyzes 111 journal of sustainable architecture and civil engineering 2022/1/30 the results of the study are reported in table 5 where the mass and gwp emissions for the materials of the different house models during the product phase (a1 – a3) are shown, the biogenic carbon in the material is reported as negative values. the house model with hemp fibre has the largest mass and the house model with glass wool has the smallest mass. during the product phase, the house model with glass wool has the highest net emission and the house model with hemp fibre has the lowest net emission. results table 5 mass per square meter habitable area [kg/m² habitable area] and global warming potential per square meter habitable area [co₂e/m² habitable area] material mass (kg/m² habitable area) gwp (co₂e/m² habitable area) hemp fibre cellulose glass wool hemp fibre cellulose glass wool fossil biogenic fossil biogenic fossil biogenic hemp fibre board 7.8 4.7 -9.5 l o o s e wool 20.0 12.4 -25.1 cellulose board 6.4 4.8 -8.2 l o o s e wool 16.3 12.2 -21.1 glass wool board 3.4 2.7 l o o s e wool 8.7 7.7 wood 61.2 58.7 59.4 5.3 -96.1 5.1 -92.3 5.1 -93.3 concrete 331.8 329.4 328.8 48.0 47.6 47.6 gypsum board 16.6 16.6 16.6 4.7 4.7 4.7 eps 5.3 5.3 5.3 21.4 21.2 21.1 rebar 3.7 3.6 3.6 2.7 2.7 2.7 roof tile 27.5 27.2 27.1 6.2 6.1 6.1 osb board 5.4 5.4 5.4 2.4 -8.5 2.4 -8.5 2.4 -8.5 window 5.7 5.7 5.7 14.0 14.0 14.0 door 0.8 0.8 0.8 4.5 4.5 4.5 balcony door 0.5 0.5 0.5 1.2 1.2 1.2 pe-foli 20 mm 0.2 0.2 0.2 0.9 0.9 0.9 asphalt saturated felt 6.0 5.9 5.9 5.1 5.0 5.0 amount 491.9 481.7 471.0 133.4 -139.2 132.3 -130.1 125.5 -101.8 net amount -5.8 2.3 23.7 lca table 6 shows the lca of hemp fiber, cellulose, and glass wool that were used as insulation materials in house. the largest emissions came from material production (a1 – a3), followed by the combustion of organic material (waste and building materials) in the final stage (c3). the emissions in c3 correspond to the combustion of the biogenic carbon from a1 – a3 and a5. the largest uptake of biogenic carbon was in the product phase (a1 – a3) and in material waste (a5). the negative value in stage d shows how much emissions the energy recovery (stage c3) comjournal of sustainable architecture and civil engineering 2022/1/30 112 phase gwp hemp fibre cellulose glass wool fossil biogenic fossil biogenic fossil biogenic a1 – a3 133.4 -139.2 132.3 -130.1 125.5 -101.8 a4 10.9 11.45 11.3 a5 5.4 -11.1 5.2 -10.4 5.3 -4.9 b6 30.0 30.1 30.0 c2 3.5 3.5 3.4 c3 150.2 140.3 111.9 c4 0.1 0.1 0.1 d -54.2 -50.2 -36.8 amount 273.8 -150.3 270.7 -140.4 250.6 -112.0 net amount 123.5 132.3 138.6 phase cellulose recycle cellulose unused fossil biogenic fossil biogenic a1 – a3 122.4 -146.6 132.3 -130.1 a4 12.0 11.5 a5 5.1 -10.5 5.2 -10.4 b6 30.1 30.1 c2 3.5 3.5 c3 157.0 140.3 c4 0.1 0.1 d -57.9 -50.2 amount 272.2 -157.1 270.7 -140.4 net amount 115.1 132.3 table 6 lca for the house model [kg co₂e/m² habitable area] pensated outside the system limit. in steps a4, b6, c2 and c4, there are small differences between the different houses. the house model with glass wool has the highest net emissions during the life cycle and the house model with hemp fibre has the lowest net emissions. analysis of cellulose the results of the sensitivity analysis in the lca of the different raw materials for cellulose are presented in table 7. the cellulose production based on unused paper as raw material has the highest net emission compared to the cellulose based on recycled paper. cellulose with recycled paper has the lowest net emission of all insulation materials in the study. table 7 lca and sensitivity analysis for unused and recycled raw material for cellulose [kg co₂e/m² habitable area] sensitivity analysis of glass wool the results of the emissions over the life cycle of glass wool for changed input data is shown in table 8. the generic data source results in higher net ghg emissions than the data based on the epd. sensitivity analysis of heating system the results in table 9 show how the energy use, the fossil emissions and the operating costs vary between geothermal and district heating as a heat source in the house models during their life113 journal of sustainable architecture and civil engineering 2022/1/30 table 8 lca and sensitivity analysis for glass wool [kg co₂e/m² habitable area] phase glass wool generic data glass wool epd fossil biogenic fossil biogenic a1 – a3 129.7 -101.8 125.5 -101.8 a4 11.4 11.3 a5 5.4 -10.2 5.3 -10.2 b6 30.0 30.0 c2 3.4 3.4 c3 111.9 111.9 c4 0.1 0.1 d -36.8 -36.8 amount 254.9 -112.0 250.6 -112.0 net amount 143.0 138.6 table 9 energy use, fossil emissions and operating costs for the house models with district heating system or geothermal heating system [kwh /m²year, kg co₂e/m² habitable area, sek/m² habitable area] insulation energy consumption [kwh/m²year] fossil emission [kg co₂e/m² habitable area] operating cost [sek/m² habitable area] district geothermal district geothermal district geothermal hemp fibre 63.9 45.8 30.0 107.6 2071 616 cellulose 64.1 45.6 30.1 107.2 2077 613 glass wool 63.9 45.8 30.0 107.6 2071 616 time. the highest energy use is linked to district heating, the largest fossil emissions are linked to geothermal heat and the highest operating cost occurs when using district heating. sensitivity analysis of fuel the results for transport with electricity as fuel are shown in table 10 and this is compared with. the result shows that the fossil emissions reduced by 5.6 – 5.8 kg co₂e per m² habitable area depending on which insulation material is used in the house. phase fuel hemp fibre cellulose glass wool fossil biogenic fossil biogenic fossil biogenic a1 – a3 133 -139.2 132.3 -130.1 125.5 -101.8 a4 8.0 8.6 8.5 a5 5.4 -11.1 5.2 -10.4 5.3 -4.9 b6 30.0 30.1 30.0 c2 0.7 0.7 0.7 c3 150.2 140.3 111.9 c4 0.0 0.0 0.0 d -54.2 -50.2 -36.8 amount 268.0 -150.3 267.1 -140.4 245.1 -112.0 net amount 117.7 126.6 133.1 table 10 sensitivity analysis with electric transports [kg co₂e/m² habitable area] journal of sustainable architecture and civil engineering 2022/1/30 114 climate declaration (a1 – a5) insulation with biogenic carbon without biogenic carbon hemp fibre -0.7 149.7 cellulose 8.5 149 glass wool 30.1 142.1 lcc phase hemp fibre cellulose glass wool investment 3906 3267 3302 operation 2071 2077 2071 final handling 448 443 443 total 5467 4830 4861 table 11 climate declaration with and without biogenic carbon (a1 – a5) [kg co2e/m² habitable area] sensitivity analysis of biogenic carbon (a1 – a5) the results of the climate declaration (in lca phases a1 – a5) are shown in table 11. the house model with glass wool as an insulation material has the highest net emissions and the house model with hemp fiber as an insulation material has the lowest net emissions when the biogenic carbon is included. when only the fossil emissions are considered, the house model with hemp fibre has the highest fossil emissions and the house model with glass wool has the lowest. table 12 results from the net present value method [sek/m² habitable area] discussion if only the investment cost is studied, the data shows that hemp fibre is by far the most expensive, see table 13. lcc the result of the lcc according to the net present value method is presented in table 12. this shows that the highest cost during the entire life cycle is borne by the house model with hemp fibre insulation and the lowest cost house is borne by the house model with glass wool insulation. table 13 cost of insulation spread over square meters of habitable area [sek/ m² habitable area] cost hemp fibre cellulose glas wool wall 300,547 212,517 186,433 roof 615,600 44,549 139,424 total amount 916,147 357,066 325,857 the most unexpected with the study it was a surprisingly small difference in the energy consumption between the insulation materials during the b-phase. it was also unexpected that the climate declarations do not include biogenic carbon which we shows can have a large impact on the total emissions. the results of the lca study show that the house model that is insulated with hemp fibre has the smallest net emissions over the entire life cycle and thus means the best choice for the environment. the results show that due to the increased volume of materials, hemp fibre insulation contributes 9 % more fossil emissions than glass wool insulation. on the other hand, hemp can bind 34 % more co2 and thus the net emissions will be 12 % less emissions compared to the choice of glass wool. that insulating materials such as glass wool contribute to higher net emissions 115 journal of sustainable architecture and civil engineering 2022/1/30 than the organic insulating ring materials is confirmed by results from other studies conducted by zabalza bribián, valero & aranda usón (2011). this study does not show that cellulose has better environmental performance than hemp, which dickson & pavia (2021) study does. the reason is that our study only looks at the carbon flows in lca, while dickson & pavia’s study (2021) includes four different parameters for lca, including acidification. this shows the importance of clarifying what the studies examine, the system boundaries and the scope of the study. during the product phase (a1 – a3) there are large differences between the different materials, the hemp house stores more carbon dioxide in the organic building materials than what is emitted to produce all other materials in the building. in terms of the total amount of insulation material in the houses alone, hemp fibre insulation contributes to a net emission of -17.46, cellulose with -12.29 and glass wool with 10.34 kg co₂e / m² habitable area. our results shows like dickson & pavia (2021) and zampori, dotelli & vernelli (2013) that plant-based material like hemp has lower gwp than rock wool because the material binds more carbon dioxide and need less energy in the product phase of the material. despite the high heat capacity of hemp fibre and cellulose, the density is not high enough to store heat in the material, which means that stage b does not differ significantly between the materials. the study shows that the combustion of materials in stage c, contributes to large emissions. it would therefore be good to reuse the material as far as possible, to create a long waterfall effect. none of the insulation materials showed negative net emissions over the entire life cycle in the building. this means that no house became a coal sink. had the materials been recycled in the final stage instead of being burned as zabalza bribián, valero & aranda usón (2011) strongly advocated, it could have had an effect on the result for hemp and cellulose houses, see chapter 6.3.1.2 in our study (eriksson, hult & karlsmo 2021). the results of the economic analysis, see figure 2, show that the choice of hemp fibre is 20 % more expensive than the traditional glass wool insulation in sweden, which is also reported in a study by dickson & pavia (2021). the cost of insulation per square meter habitable area showed fig. 2 differences between epd and generic data in different designs of the material glass wool that hemp fibre is 2.8 times more expensive than glass wool and 2.6 times more expensive than cellulose insulation, see table 13. cost of insulation based on square meters habitable area [sek / m² habitable area]. study agrees with kymäläinen & sjöberg (2008) study which showed that the bast fibre insulation has double the price compared to conventional insulation. the difference in this study shows that the cost of hemp fibre insulation is almost three times higher. it is in particular the loose wool insulation of hemp that stands out with a 4.4 times higher price than glass wool loose wool. the increase is due to a higher purchase price / volume of materials and the fact that the house with hemp insulation needed thicker walls to achieve the same u-value as the glass journal of sustainable architecture and civil engineering 2022/1/30 116 fig. 3 climate declaration with (a) the biogenic carbon in the hemp fibre, cellulose and glass wool house in stages a1 a5 and (b) without the biogenic carbon in the hemp fibre, cellulose and glass wool house in stages a1 – a5. (a) (b) and cellulose house types. the cheapest is the cellulose insulation with 35 sek / habitable area (approx. 1 %) compared to the glass wool, see figure 2. the cellulose in this study had a lower price than those shown in a study done by kymäläinen & sjöberg (2008). the price difference may be due to the fact that their input data for costs were from 2005 and 2007, respectively, and this study collected data during april 2021. the result for the climate declaration, see figure 3, shows the major impact that the inclusion of biogenic carbon has on the result for the climate declaration. this shows that if the national board of housing, building and planning or sis does not introduce guidelines that biogenic carbon must be reported (or if the national board of housing, building and planning does not publish value of biogenic carbon) in the climate declaration, the organic materials can have high fossil emissions. this means that materials such as hemp fibre insulation will not be seen as an advantageous material. as the national board of housing, building and planning & the swedish environmental fig. 4 different emissions during the life cycle with hemp fibre, cellulose (unused), cellulose (recycled) and glass wool insulation protection agency (2019) point out that the construction sector has great opportunities to become environmentally friendly by using biomaterials such as carbon sinks, it should be of the utmost importance to report the biogenic carbon. the sensitivity analysis shows that the biogenic carbon entails major changes in the result of the materials’ climate impact. discussion about the impact of input data on the result (islam, jollands & setunge 2015; pedersen weidema & suhr wesnæs 1996) justified a study of input data in the form of a sensitivity analysis. the sensitivity analysis for the raw material, see figure 4, to the insulation material reported that cellulose on recycled paper had the lowest net emissions. when comparing all materials over the 117 journal of sustainable architecture and civil engineering 2022/1/30 fig. 5 differences between epd and generic data looking at the glass wool insulation entire life cycle, it can be concluded that cellulose on recycled paper gives the lowest net emissions and would thus have been the material that would have been preferred with regard to the environmental aspect. the sensitivity analysis for glass wool, see figure 5, reported that the difference between input data was 3 % for net emissions during the life cycle. the reason may come from the fact that the generic data is based on an average of several epds and has a 25 % surcharge on net emissions. sis (ss-en 15978: 2011) and the national board of housing, building and planning (boverket 2021c) call for the use of epds in the first instance. although there are difficulties in keeping databases up to date, the climate database should be so, as all data comes from a recently published test version (islam, jollands & setunge 2015; boverket 2021a). one conclusion of this result is that the data source is important for the result. the results of the sensitivity analysis show that the choice of heating system, see figure 6, had the greatest impact during the building’s life cycle, both net emissions and operating costs varied greatly between the different heating systems. this is due to the low values of net emissions that veab (u.å.) generated by their district heating production. the values from the rock heat depend on the electric mix used. the electricity mix can vary between different countries and thus give different outcomes on the result depending on in which country the building is located (trafikverket 2021; energi företagen 2020; dixit et al. 2010). as the operation accounts for about 32 % of the total costs, it can be concluded that the operation has a predominant significance of the building’s cost of living and the choice of heat source affect this cost. the sensitivity analysis that studied fuels for the transports shows that the building’s net emissions were affected over its life cycle. transportation powered by electricity instead of diesel reduced net emissions. most of the transports are carried out in the final stage of the house (c2, c3), which is estimated at 50 years from today. according to dixit et al. (2010), transport will over time be developed with more fuel-efficient methods and more efficient energy consumption. this means that the result of the sensitivity analysis provides a better picture of how future technology will affect the net emissions for the building during the life cycle. as the development of both lca and lcc is complex and extensive, system boundaries were defined to clarify which different parameters the study takes into account. in order to focus on the most important parameters, certain parts of the lca and lcc were omitted. for example, only carbon flows are studied, which means that other interesting environmental factors are overlooked. some influence of the system boundaries’ assumption that certain stages are equal and should not be examined may have affected the result. for example, the construction phase is assumed to be the same between the different models, technically they are the same, but the density of the materials and the difference in the gross floor area may have meant that this aspect was journal of sustainable architecture and civil engineering 2022/1/30 118 conclusions important. through the choice of system boundaries, the result is affected and this can, according to islam, jollands & setunge (2015) and senga kiessé et al. (2017) make the result difficult to assess. when the number of elections is reduced, according to senga kiessé et al. (2017) that the result becomes more subjective but that it also creates uncertainty as this neglects the sensitive interaction. if the study had been ongoing for a longer period, more parameters could have been included in the study. the time aspect affects the choice of system boundaries. the results of the study can be complicated to compare with other studies as the system boundaries can differ considerably. strengths of the study is the sensitivity analyses that shows what happens when the numbers are changed. however, more insulation materials and house models could be considered, in further sensitivity analyses. notwithstanding, the study is sufficient enough to draw conclusions, to fill gaps in knowledge and hopefully inspires more scientific studies in this field. bouloc p., allegret, s. & arnaud l. (red.) (2013). hemp: industrial production and uses. oxfordshire, boston: cabi international, ss. 3-25, 238-313.https://doi. org/10.1079/9781845937935.0000 bfs 2011:6. boverkets byggregler allmänna föreskrifter och råd [the national board of housing, building and planning’s building regulations general regulareferences tions and advice] (consolidated version). karlskrona: boverket. boverket (2021a). klimatdeklaration av byggnader [climate declaration of buildings]. https://www.boverket. se/sv/byggande/hallbart-byggande-och-forvaltning/ klimatdeklaration/ [2021-04-06] boverket (2021b). utsläpp av växthusgaser från bygg if the climate goals are to be achieved, the construction sector must make changes, but it is important to make the right changes. this study shows that the greatest impact on net emissions during the building’s life cycle comes from the choice of heating system. the difference between switching from district heating to geothermal heating resulted in an increase in net emissions by 63 %. although the choice of heat source affects net emissions the most, the study shows that the choice of insulation material has effects in ghg emissions. in the house model, the choice of hemp fibre insulation results in a net emission reduction of 12 % compared with glass wool insulation. cellulose resulted in a 5 % reduction in net emissions compared to glass wool insulation. hemp insulation contributes to climate impact with a net emission of 124, cellulose 132 and glass wool 139 co₂e per m² habitable area. the choice of insulation material affects the cost of building the model house. when choosing hemp fibre insulation instead of glass wool, the price increases by 20 %. if cellulose is used instead, the price will be similar (the reduction is 0.01 %). choosing hemp fibre insulation gives a cost of 5467 sek per m² habitable area, cellulose 4830 and glass wool 4861 sek per m² habitable area. as biogenic carbon has shown a major impact on the results of this study, and in particular on climate declarations, the concept of biogenic carbon and its entity should be developed and clarified by institutes for standards to create transparency and to take the time aspect of biomaterial renewal time into account biogenic carbon. the system boundaries are central to lca and lcc studies as these define the scope of the study and thus shape the result. it should be emphasized that the results of this study must always be interpreted within the context of the study. declaration of competing interest this research was supported by linnaeus university växjö, sweden. the authors declare that there is no financial interests for the study and they have no personal relationships that can affect the result. acknowledgments the authors acknowledge ylva eriksson who has participated in the bachelor thesis that forms the basis of the article and prof. ambrose dodoo for reading the manuscript, leaving critical comments and analytical support. 119 journal of sustainable architecture and civil engineering 2022/1/30 och fastighetssektorn [emissions of greenhouse gases from the construction and real estate sector]. https:// www.boverket.se/sv/byggande/hallbart-byggande-och-forvaltning/miljoindikatorer---aktuell-status/ vaxthusgaser/ [2021-03-25] boverket (2021c). om boverkets klimatdatabas [about the national board of housing, building and planning’s climate database]. https://www.boverket.se/sv/byggande/hallbart-byggande-ochforvaltning/klimatdeklaration/klimatdatabas/om-klimatdatabasen/ [2021-05-07] boverket (u.å.). vilken innetemperatur ska användas vid energiberäkning? 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(2013). life cycle assessment of hemp cultivation and use of hempbased thermal insulator materials in buildings. environmental science & technology, 47(13), p. 7413 7420. https://doi.org/10.1021/es401326a about the authors mathilda hult graduated student, bachelor’s degree linneaus university, faculty of technology department of building technology address universitetsplatsen 1, 352 52 växjö, sweden tel: +46 (0)772-28 80 00 e-mail: manmk09@student.lnu.se sara karlsmo graduated student, bachelor’s degree linneaus university, faculty of technology department of building technology address universitetsplatsen 1, 352 52 växjö, sweden tel: +46 (0)772-28 80 00 e-mail: skaev07@student.lnu.se this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 85 journal of sustainable architecture and civil engineering 2019/2/25 *corresponding author: vytautas.baltus@ktu.lt parametric architecture today and tomorrow received 2018/10/01 accepted after revision 2019/01/12 journal of sustainable architecture and civil engineering vol. 2 / no. 25 / 2019 pp. 85-89 doi 10.5755/j01.sace.25.2.21698 parametric architecture today and tomorrow jsace 2/25 http://dx.doi.org/10.5755/j01.sace.25.2.21698 vytautas baltus*, laura jankauskaite-jureviciene, tadas zebrauskas kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania introduction in the past fifteen years’ avant-garde architectural practice has been developing in the field of parametric design at the phenomenal speed. this success can be attributed to the development of advanced computer software, previously used for animation and rendering. the parametric design method uses advanced computer scripts which transforms mathematic algorithms of relations between parameters into creations of complex geometries, which were almost impossible to produce and even imagine without it. intriguingly, there are examples of parametric design logics to find form and test structural tensions predating computers i.e. structural tests of a. gaudi (fig. 1), f. otto, l. moretti. question remains will these mathematical equations inputted thru scripting language as algorithms will add additional value to the design, or traditional, intuitive way of designing still can be relevant enough in 21st century. there are doubts that without deep intellectual background parametric design process can play for the play’s sake with the shapes of objects, buildings and urban structures. keywords: parametric design, architecture, urban. parametric design has its roots in the digital animation techniques, but recently, with emerge of advanced design systems and scripting techniques, it became dominant style for avant-garde practice, which “sell” projects to clients as performative solutions based on what clients want their buildings to achieve spectacular views, efficient circulation, improved working conditions, increased productivity, better use of resources and materials, more efficient communication. architects do not talk about meaning, symbolism, metaphors, or even aesthetics. they know exactly what clients want and work with software, diagrams, parameters and spreadsheets. they never can tell what a building will look like until they consult every member on their team and run their designs through numerous variations before a particular version appears, based on allowing the data to emerge into a particular form. and the final form gets chosen out of numerous others that look only slightly different. these design methods follow a certain formulaic pattern of creating buildings based on calculation or programming rather than inspiration. so it is hard to expect masterpieces like chappelle notre-dame-du-haut de ronchamp (fig. 2) or yoyogi national gymnasium, that were done as artistic and intuitive work that required a mixture of intuition, mathematics and geometry. there is less place for emotional architecture. architects are looking for reasons for every curve and spike. they seem afraid of being accused as “artistic” or even “wasteful” (belogolovsky, 2015). journal of sustainable architecture and civil engineering 2019/2/25 86 the fascination with technology is a way of introducing new formal vocabulary that is going to explore certain spatial configurations that our mind has difficulty imagining. parametric design encapsulates superior capacity to articulate programmatic complexity and our effort of putting it all into algorithms and scripts instead of hand sketch are compensated by adding superior intelligence layer, rewarding us with exploration of generated surprising discoveries of unimagined design outcomes. in the future architects, or even clients will explore the whole range of possible solutions that the variability of the initial parameters allows. discussion fig. 1 structural test of sagrada familia by a. gaudi fig. 2 chappelle notredame-du-haut de ronchamp by le corbusier not everyone, however, is enamoured by computer design or the promise of parametric systems. christopher alexander, even in 1965, warned that architects might “fatally distort the nature of design by restating design problems solely for the purpose of using the computer.” (schumacher, 2009) he did not believe that there were design problems environmental or architectural so complex that they require a computer to solve, and he was not convinced that architects would not oversimplify design complexity to meet the limited input and operational capacities of their computers. the computer could not keep pace with the facility of human intuition for inventing architectural forms and deriving design solutions for complex problems. mathematical parametric and algorithmic procedures most often have proven far too rigid to productively engage the complex cultural, societal, economic and political projects facing architects today. designing buildings and cities using parametric and scripting design tools may often appear visually stunning, but for the most part these designs tend to incorporate far too many blind assumptions to be able to respond with nuance to real world situations. moving away from delimiting input techniques derived building forms and urban typologies, but the design vanguard has begun focusing more on the performative and affective qualities of architecture. the parametric design generates geometry from the definition of a family of initial parameters and the design of formal relations they keep with each other. algorithms are used as a primary design methodology which employs computer scripting, thus, excluding initial and intuitive design idea, hand sketch of final geometry at first (fig. 3). nevertheless, advocates of parametric design argue that such an innovative adaptation of architecture and urbanism retools and adapts the discipline to the demands of the socio-economic era. parametric design techniques employment of animation, simulation and form-finding tools, as well as parametric modelling and scripting addresses societal demand and inspires a new collective movement with radically new ambitions and values. thus, we are confronted with a new style rather than just with a set of techniques. above aesthetic recognisability it transforms into a sense of epochal phenomenon. modernism was accused of single style dullness, while parametric design allows continuous differentiation, versioning and customisation. virtuosity and refinement, facilitated by the develop87 journal of sustainable architecture and civil engineering 2019/2/25 ment of parametric design tools and scripts allow precise formulation and execution of intricate correlations between elements and subsystems. shared concepts, computational techniques, formal repertoires and tectonic logics that characterise this work are crystallising into a solid new paradigm of architecture. fig. 3 example of algorithm design method fig. 4 zaha hadid’s architects parametric design example for urban structure creative exploitation of parametric design systems articulates increasingly complex social processes. aesthetically it is the elegance of ordered complexity and the sense of seamless fluidity, akin to natural systems. architectural progression of styles proceeds together with innovations of collective endeavour, cumulative advancements in technology. each style has its core of principles and a characteristic way of tackling design tasks. the parametric design programme consists of methodological rules: some tell us what paths to avoid and other what pats to pursue. it formulates strictures that prevent relapse into old patterns and preferred techniques as guiding principles that allow to work forward. the defining principles of parametric design style are reflected in taboos and dogmas of contemporary avant-garde design culture: avoiding rigid geometric primitives like squares, triangles and circles, to avoid simple repetition of elements and consider all forms to be parametrically malleable, differentiate gradually, correlate systematically (fig. 4). designer’s realisation of unique formal and organisational opportunities are afforded by the continuous advancement of the sophisticated computational geometry design processes. scripting and parametric modelling are essential to compete today within avant-garde scene and mastering and advancing in these techniques is a must for an architect. however, the advancements of techniques should go hand in hand with formulation of further ambitions and goals, such as rationality of parametric design, which, still in it’s implementational infancy, might involve accentuation, figuration and responsiveness able to produce modulations of morphologies and powerful architectural or urban effects facilitating field orientation. although no unique optimal solution exists and each computation is different, characteristic patterns emerge in different regions of the parametric space. le corbusier’s theoretical statement on urbanism starts with eulogy of the straight line and the right angle as means by which man conquers nature. contrast of man’s way with the donkey’s way is depicted in the city of tomorrow as follows: “man walks in a straight line because he has a journal of sustainable architecture and civil engineering 2019/2/25 88 goal and knows where he is going; he has made up his mind to reach some particular place and he goes straight to it. the donkey meanders along, meditates a little in his scatter-brained and distracted fashion, he zig-zags in order to avoid larger stones, or to ease to climb, or to gain a little shade; he takes the line of least resistance.” (le corbusier, 1925) le corbusier admires urban order of romans and rejects sentimental attachment to the picturesque irregularity of medieval cities: “the curve is ruinous, difficult and dangerous; it is a paralysing thing.” le corbusier insists that “the house, the street, the town should be ordered; if they are not ordered, they oppose themselves to us.” le corbusier’s limitation is not his insistence upon order, but his limited concept of order in terms of classical geometry. phenomena like the “donkey’s path” and the urban patterns resulting from unplanned settlement processes can now be analysed and appreciated in terms of their underlying logic and rationality. le corbusier realised that although “nature presents itself to us as a chaos, the spirit which animates nature is a spirit of order.” however, understanding of nature’s order was limited by the science of his day. today we can reveal the complex order of those apparently chaotic patterns by means of simulating them. modernism was founded on the concept of universal space. parametric design differentiates fields. there are no platonic, discrete figures or zones with sharp outlines. there are no more landmarks to hold on, no axis to follow and no more boundaries to cross. parametric design concept of deep relations also leads to multiple adaptations that trigger ordered complexity and replaces monotony of planned developments or disorienting visual chaos. it further intensifies correlations, involving systematic modulation of tectonic features. parametric design is able to further coordinate pragmatic concerns and articulate them with all their rich differences and relevant associations. the overall idea of parametric design holds an important strategic potential for creating a positive impact on the environment of architectural and especially urban design field, due to its important practical, economical, or later even maybe measured ecological dimension that can be added as one of the parameters in the algorithm. only in last decade parametric modelling gone from being a mathematical trick employed by gaudi, otto, sutherland and some engineers to being a regular part of architectural practice. in architecture parametric modelling is complemented by an utilitarian dogma for exploring all possibilities offered by such model. this exploration is facilitated both through modification of model parameters and their relationships. in present day parametric modelling is no longer the exclusive domain of overtly parametric tools, but parametric equations quietly drive many bim tools, they manifest in textural script languages and are exposed by graph-based visual scripting interfaces. parametric modelling is present, in some form, on most contemporary architectural projects and probably will be a must for future profession. conclusions we have all at some point used a spreadsheet to solve a specific mathematical problem. starting with intentionally chosen values, and under certain rules that we have imposed on the system when setting it up, we are able to instantly obtain very complex results, which also, can be immediately recalculated by simply tweaking the original parameters. but, what if we could mimic this process with geometry? the ground of parametric design is the generation of geometry from the definition of a family of initial parameters and the design of the formal relations they keep with each other. it is about the use of variables and algorithms to generate a hierarchy of mathematical and geometric relations that allow you to generate a certain design, but to explore the whole range of possible solutions that the variability of the initial parameters may allow. 89 journal of sustainable architecture and civil engineering 2019/2/25 the benefits of this process are immediate. it is a huge leap in the quality of our process, since we are not bound by our tools anymore; now it will be us who design our own tools. on the other hand, parametric design is fundamental when minimising the effort needed to create and test design variants. generating an automated process eliminates tedious repetitive tasks, the need for complicated calculations on the fly, the possibility of human error, and generates huge shifts in the outcomes with slight variations of the original parameters. parametric thinking introduces the shift in the mindset between the search for an specific static and defined formal solution, and the design of the specific stages and factors used to achieve it. it is the use of algorithms and advanced computational techniques not for the sake of drawing shapes, but creating formal possibilities. it is not about producing a solution, but the family of possible outcomes. it is the shift from using cad software as a representation tool, to do it as a design tool. it is, altogether, the new paradigm. referencesglancey j. 2017. what’s so great about the eiffel tower? london, lawrence king publishing, 140-141. belogolovsky v. 2015. conversations with architects in the age of celebrity. berlin, dom publishers. 30-31. le corbusier. 1929. urbanisme. new york, payson & clarke ltd., 5-18. schumacher p. 2009. parametric patterns. archit design, 79: 28-41.https://doi.org/10.1002/ad.976 about the authorsvytautas baltus lecturer kaunas university of technology, faculty of civil engineering and architecture main research area architectural design address studentu str. 48-309, lt-51367 kaunas tel. +370 606 30306 e-mail: vytautas.baltus@ktu.lt laura jankauskaitejureviciene lecturer kaunas university of technology faculty, of civil engineering and architecture main research area architectural design address studentu str. 48-309, lt-51367 kaunas tel. +370 688 74418 e-mail: laura.jankauskaitejureviciene@ktu.lt tadas zebrauskas lecturer kaunas university of technology faculty of civil engineering and architecture main research area architectural design address studentu str. 48-309, lt-51367 kaunas tel. +370 618 32820 e-mail: tadas.zebrauskas@ktu.lt https://doi.org/10.1002/ad.976 3 darnioji architektūra ir statyba 2013. no. 2(3) journal of sustainable architecture and civil engineering issn 2029–9990 the landscape of panemunė castles: value and protection problems jūratė jurevičienė, marija burinskienė* vilnius gediminas technical university, research institute of territory planning, saulėtekio av. 11, vilnius, lithuania *corresponding author: marija.burinskiene@vgtu.lt http://dx.doi.org/10.5755/j01.sace.2.3.3981 the article studies historic and cultural value of landscape having formed in the mid-section of the right bank of nemunas river (between jurbarkas and kaunas). the article gives methodological principles and criteria based on which a historic expressiveness of landscape is assessed. a historic value of the study territory is described, also its unique features in the context of lithuania, and the relevant aspects of cultural cognitive potential. it is revealed that till now the largest attention has been paid to the existing buildings of panemunė (gelgaudai, vytėnai), raudonė and raudondvaris residential castles, however, they are only partly integrated into the local social structure. when forming landscape the sites of the former crusader castles on the nemunas riverbank, namely seredžius ii (palocėliai, the supposed site of dubysenburg) and dubysa ii (pilaitė) are insufficiently respected. the expressiveness of medieval defensive structures and the spatial interaction of their remains create in the study territory an important but yet unusable potential of mental landscape. keywords: panemunė castles, nemunas valley landscape, historic and cultural potential of the territory. 1. introduction lithuania has several regions distinguished for their exclusive historic and cultural value. one of those is the valley and its surroundings situated in the middle part of nemunas river. it is obvious, that vilnius, trakai and kaunas castles in a present-day lithuanian understanding of historic and cultural heritage were and still are the structures of great significance, having acquired even a status of national symbols. however, the image of midsection of panemunė (the term refers to the territory situated on the bank of nemunas river) has remained fragmentary and is related only to residential masonry castles built in the renaissance period and later reconstructed, the role of which in the history of lithuania was of no particular importance. the article studies the most valuable features of landscape having formed on the right bank of nemunas river valley, in the section between jurbarkas and kaunas cities. in the article the landscape of this section is termed as the landscape of panemunė castles with the emphasis on its mental aspect1 and a visual domination of three residential masonry castles: panemunė, raudonė and raudondvaris. it is believed that landscape, which is formed seeking for sustainability, must integrate and reflect all the layers of historic and cultural value having formed in a course of territorial evolution, paying the largest attention to the most important of them. the article is based on the currently available results of archaeological, historical 1 in article 1 of the european landscape convention the landscape is described as part of the land, as perceived by local people or visitors. and architectural investigations of the study area, also on the method of historical reconstruction and the recently implemented exploratory, architectural and landscape investigations2. according to the general plan of the territory of republic of lithuania the panemuniai region, based on the character of its cultural values and territorial distribution of the types of accumulation areas, is attributed to one of the five regions of lithuania with the dominating historical heritage. the plan indicates that the main historical weight in this region is represented by liškiava, merkinė, alytus, punia, pypliai, seredžius and veliuona mounds, panemunė castles, kaunas city and padubysiai archaeological memorial complex (general plan of the territory of republic of lithuania 2002). however, it could be stated that the current level of exploration of the cultural value of the territory between kaunas and jurbarkas does not correspond to its significance being declared. up to now, only single objects of immovable cultural heritage and some urbanized locations of this area have been studied. comprehensive and complex investigations from the point of view of heritage protection were carried out only in panemunė, raudonė and raudondvaris castles. historians and archaeologists have made several studies of the lithuanian and crusader castle sites that have not survived on the right bank of the nemunas river, however, no systematic territorial investigations 2 in 2012, the vgtu territorial planning institute started implementing a scientific research project “innovative regeneration methods of architectural heritage: panemunė castles“, supported by the research council of lithuania (project no. vat-12053). 4 were implemented. though the former territorial system of defensive fortifications, created by lithuanians during the lithuanian-teutonic wars, has been mentioned in the works of many historians, the exact site and the evolution of important parts of the system have not been known yet (kvizikevičius 2003). insufficient historical investigations create preconditions for studying only the separate aspects of the cultural value of this landscape. 2. research methodology in a present-day postmodern society the value of landscape is sought to be unclosed in various aspects. in various european countries, when studying a particular case of landscape, depending on its origin, context, the problem to be analysed and the aim of work, several models are often applied. if still two decades ago when studying landscape the largest attention was paid for identifying the historic and architectural significance of buildings and their ensembles of exclusive value, at this time the largest importance is attached to the landscape as a whole in order to emphasize interaction between its separate parts. the object to be protected is often termed as the whole environmental fabric making the landscape. a special importance is also given to the subjective values of site identity. since landscape heritage is the result of the past cultural human activities and the creation of today’s cultural and social opinions, its origin is sometimes termed as “doubly cultural” (fairclough 2008). in lithuania, in the works related to the landscape problems landscape is still understood as a territorial analogue or even as the whole of its missing greenery. however, another attitude is being gradually established that the value for landscape, as for any other object, is given by society, and the protection of its cultural value in all its forms grows from the values assigned to it by the users of the territory – “how much and how we would talk about the surrounding universe and its features, essentially, we talk about the fact of how we perceive it” (zaleckis 2011). one of the aims of the european landscape convention related to the cultural heritage protection is to assess the landscapes defined depending on the particular values assigned to them by the interested parties and the population concerned. a strategy of creating democratic environment requires giving a possibility to local communities to express their opinion about the cultural value of the environment. the burra charter has given a recognizing that cultural importance of building or site was extended to its setting, its contents and the knowledge that pertained to it. it emphasized that “cultural significance is embodied in the place itself, its fabric, setting, use, associations, meanings, records, related places and related objects” (icomos australia, 1999). in lithuania, a mental aspect of landscape conception has been legitimated in the currently-valid regulations of international level (european landscape convention 2010, article 1a), however, it is only fragmentary reflected in the national legal acts regulating territorial management. definitions of landscape, given in the national legal acts, do not reveal its nature – landscape is described as a territorial combination of natural and (or) anthropogenic components of the land surface, whereas, cultural landscape is defined as a landscape created by human activities and reflecting its coexistence with the environment (law on protected areas of the republic of lithuania 2001, law on protection of immovable cultural heritage of the republic of lithuania 2004), or a landscape purposefully formed and satisfying the needs of biological, psychological (information, aesthetic), social, ergonomic (suitability to the activities) or economic environmental quality in living, working and recreation (the list of landscape policies of the republic of lithuania 2004). different documents of territorial planning of lithuania give references to the territorial coherence of landscape’s material parts (general plans of the republic of lithuania or of different municipalities, special plans of protected areas), however, investigations of landscape as of a mental object are still left for the future, and no general methodology for investigating this field has been developed. in an emotional reflection of landscape a symbolic value is interlaced with historic, associative and aesthetic aspects. recently, it is more often spoken about “spirit of place” (genius loci), though there is neither its research methodology nor the obligation to study it when preparing territorial planning documents. lithuania in this respect is not an exception – no exact criteria for the conformity of genius loci to the list of the world heritage have been formulated (cleere 1995). in lithuania, state and municipal institutions could act as the organizers of special plans for landscape development, but because of expensive and longlasting process the plans are initiated only in exceptional cases. landscape in this research is studied as a field of interaction between its territorial elements, components and functional sociotopes. the main approach is that an integral unity of landscape components is one of the underlying peculiarities of its cultural value determined by the landscape origin itself. also, a methodical approach is used that historical value is not stable, it is necessary to expand it with new aspects – a valuable object shall be not only old but also shall preserve for the past and living generations the memory of important (i.e. selected) past events (fish 2008). the paper studies both the present and the fragmentary survived or unrecognizably extinct spatial, semantic and functional relations between residential, defensive and communication infrastructure objects. taking into account that the study region is attributed to one of the five regions of historical domination in lithuania and following a methodical approach of the end of the 20th century that when aiming at adaptability of work results it is advisable to analyse the most relevant and problematic elements and relations of the system (leach 2000), this work studies no other material and functional objects of the landscape. for the research the nested analysis method3 was chosen, more and more often used in studying cultural phenomena. it allows distinguishing the most relevant at the time being cultural value aspects of the study landscape without seeking for systematic perfection of research. in order to reveal the cultural value a diachronic investigation 3 a cultural philosopher nerijus milerius describes this research method as “nest in a nest“. 5 was used to define the changes in panemunė landscape in the period of essential historical breaks of the region: in the 14th and 15th century, in the 19th century and in the beginning of the 20th century, in soviet times and today. the currently started inquiry of the residents of raudonė settlement, the aim of which is to find out what aspects of the living environment, functions, cultural values are the most important for the local residents and how they are related to the castles, is supposed to correct the research results of panemunė landscape cultural value. 3. cultural value and adjustment for tourism the most attractive tourism objects in panemunė region still remain the masonry castles. castles are considered the main tourist attraction objects also in other european countries. already the romanticism epoch has attached to the medieval castles the significance of conveyor of european cultural identity. though each of medieval castles in europe had its own distinctive features of use and purpose, they always expressed the power and territorial control of the seignior (creighton 2005) – the features that stimulate their visitors to become identified with the castles. in lithuania, during the period of overdue romanticism those attributes of value were transferred to the nation. already since the end of the 19th century people searched in landscape for the relics reflecting the national ideals. however, the buildings of panemunė, raudonė or raudondvaris castles, representing by their architecture the already post-vytautas the great period not related to the fights with crusaders, were reflected in the lithuanian fiction, publications, arts and photography not so vividly and unambiguously symbolically as vilnius, trakai or kaunas castles. the masonry castles of panemunė region did not become an integral and unambiguous part of the majestic past of lithuania. a famous lithuanian writer jonas biliūnas, when describing his impressions of the journey along nemunas river in 1905, wonders and asks: “...and there peeps out from between the forest a manor or an old and already decrepit tower reminding by its crenelated peak that of a fortress of medieval ages, – a great while stands on a steep riverbank and finally vanishes beyond... and once again there comes an idea: for what purpose the tower has been built?..”. in the study territory, panemunė, raudonė and raudondvaris residential castles are up to now the main architectural objects due to their volume, scale and dominating position in the territorial silhouettes and perspective views that open from the main approaches. for the visitors, travelling along the former samogitian (žemaičių) road or coming from the northward settlements, the views of the castles are not obscured by other structures. the parks surrounding all the three castles isolate them from the adjacent settlements that still preserve plenty of objects of ancient architecture as well as low-value soviet buildings. the existing road network of the study territory also proves that the complexes of castles are poorly integrated into the common transport and communication structure. the research showed that a conditional expressiveness of territorial isolation of castle complexes can be related also to the social isolation of the castles. panemunė castle, having three high and the northern one-storey (not restored) blocks forming a close courtyard and accessed only through the northern gates of the castle, is connected to the adjacent settlement by only one minor road. the castle, in contrast to the adjacent buildings of vytėnai silesian monastery, by the purposes of its use is not adjusted for local community needs, though it holds a variety of cultural public events organized by the vilnius academy of arts (the user of the castle). the ensemble of raudonė buildings, comprised of the palace and the mill, is a partially open structure of volumes which, having found itself on the edge of existing settlement, is connected to its residential zone by two streets. though surrounded by the park from three sides, the castle ensemble is integrated into the structure of settlement spaces. the building of the former raudonė palace is occupied by the elementary school of the settlement which, though being at risk to be closed due to a decreasing number of pupils, is used for various events of local community. it’s hardly credible that castle is part of a mental landscape of the local residents – over the last several years, during consideration of various territorial planning documents in jurbarkas municipality, no responses or requests of the local residents have been received related to panemunė or raudonė castles. the buildings of raudondvaris castle complex, though also surrounded by the park from three sides, create a structure of volumes open to the environment. the raudondvaris complex, functionally divided by different users, serves various purposes (from the use for representative national celebrations to residential purpose), however, the cultural events held there are also visited by the local residents, and the park often hosts the community feasts. the increase of the number of visitors and activities in the castles meets the expectations of the local residents to have more possibilities for jobs near their home. from this point of view, the national and local interests are promoting each other. it is supposed that in future the interpreted history of the castles will play a more important role in the mental landscape of the local communities. one can guess also that local “humble values” will deserve more attention of the tourists. the current research showed that the archaeological value of the area has not been properly represented. a unique component of the cultural landscape of panemunė area – the remains of the former crusader castles – is not included into the list of the cultural heritage objects protected by state and is not adjusted for visitors. though “landscape is one of the main three (next to the written and archaeological) sources of knowledge of the past” (vaitkevičius 2010) no investigations have been made yet to determine what was the interaction between the crusader castles, the so-called motte and bailey castles, built on the nemunas riverbank to block the lithuanian veliuona and seredžius castles and the other defensive and auxiliary buildings and surrounding settlements. territorial interaction between the defensive buildings and fortifications, built by lithuanians and crusaders in the pre-christian period, is not seen, though based on the medieval logic of defence the functioning castles had to be surrounded with wide open spaces created by felling. at present, the other objects of archaeological heritage having survived in this area are also not indicated – 6 the sites of former settlements or burial-grounds. though panemunė, raudonė and raudondvaris castles were studied by archaeologists in different periods, as rasa čepaitienė (2004) states, “today archaeology becomes attractive and popular also due to the fact that its material reflects a daily life of simple people – our ancestors”. this layer of archaeological heritage in the study region has not been properly discovered and interpreted. typological structure of landscape elements can be methodically changed. in respect of rearrangement possibilities, it is important to determine the “tolerance limits” of changes. in the territory of raudonė castle a graveyard has still survived with a monument for the soviet soldiers killed in 1941–1944, the adjacency of which reduces the value of both the castle ensemble and the graveyard. in the framework of panemunė cycle route project it is planned to join to one system the already built segments of panemunė cycle route in šakiai and jurbarkas regions. in jurbarkas region it is planned to build the cycle track which will run from raudonė to seredžius. the partially constructed cycle route creates possibilities to feel a variation of close and open spaces, a variety of castles, settlements and natural views, creates preconditions to emphasize an emotional suggestibility of the landscape. a properly selected place for the track allows creating a landscape plot close to baroque aesthetics and expanding in time – having mounted up to raudonė settlement a view of the castle is unclosed, further, when driving several kilometres along the slope of kartupėnai mound the landscape of nemunas riversides is gradually showed up. having passed nine kilometres from raudonė the cycle track curves uphill to the panemunė castle park, behind which a view of šilinė inn suddenly appears. at žvyriai, behind the oak grove, the cycle track turns to skirsnemunė settlement, at molynė village goes down to nemunas and on its eight kilometres way to jurbarkas the track winds through the open nemunas riverbank. fig. 2. the north-eastern tower of raudonė castle and the graveyard of the soviet soldiers planned to be removed from the park of the castle in the territory, the major part of which is covered with forests and parks, formation of spacious visual relations is a continuous task of territorial management and supervision. the plan of panemuniai regional park management anticipates unclosing the objects and views of natural and cultural heritage with the help of felling. currently, one of the most important mounds in the history of lithuania – kartupėnai mound with an ancient settlement which is also the site of the bisenė castle, known as the very first fig. 1. the accessibility of panemunė castles by land and waterways 7 lithuanian castle to have been attacked and burnt down by the crusaders – has not been yet adjusted for observation and visiting, though it has survived in the adjacency of panemunė castle (the mound’s visual protection zone borders the defined territory of panemunė castle). a similar situation could be found at raudonėnai mound with the settlement, the mounds of jautakiai and ringovė and belvederis defensive fortification which are still overgrown with forest. however, the concrete solutions of the territorial management, the places and volumes of felling, and the access and observation sites could be determined only having implemented a complex investigation of natural and cultural values of the territory and of their presentation possibilities. territorial infrastructure of the area of panemunė castles creates preconditions to present landscape in a different way and enables to unclose and perceive the different aspects of its value. there are preconditions to form the view of the area in a linear time, comprising the complexes of panemunė, raudonė and raudondvaris castles situated on the left bank of nemunas, the already unclosed for observation seredžius and veliuona mounds, pilaičiai and palocėliai sites of an ancient castles. the riverbank and the southern valley of nemunas was an especially attractive place for creating ancient settlements. it remained vital also in later times and in the beginning of soviet period. at present, the riverbank is almost unused, almost dead and shrubby, and the former relationship between the settlements and the riverbank are cut. already in the last century, when during reconstruction the samogitian (žemaičių) road was heightened, a functional as well as a spatial relationship between the settlements and the nemunas was lost. under the project “construction of mobile piers for the development of nemunas touring route”, implemented in the framework of the national investment promotion program by alytus district municipality, šakiai district municipality and kaunas district municipality, the mobile piers were constructed in vilkija, kulautuva, zapyškis and raudondvaris settlements. though large european union funds were invested into the infrastructure of inland waterways, navigation in nemunas river is still stagnant. fig. 3. a view of panemunė castle from the road kaunas – klaipėda. in 2011, with the help of felling the fragmentary views of the castle were opened in recent years, a number of important works were implemented to restore and adjust the cultural heritage of panemunė area. from the point of view of visual relations and cultural value of landscape one of the most significant works was the elimination of critical condition of raudonė castle tower and restoration of its masonry – in 2005 the tower was re-opened for the visitors to observe the nemunas valley. many valuable aspects of the landscape of nemunas valley, representing integral interaction of history and natural values, still remain unclosed, however, with many regrets for insufficiently used possibilities to rapidly develop mass tourism, for the meantime one can be glad of avoiding aggressive commercialization impact on the authenticity of surroundings. from the point of view of physical condition of castle buildings the largest danger for them is caused by moisture – moisture-related problems cannot be solved locally in each building but only by assessing them all in a context of landscape. a complex of raudondvaris castle structures was formed on a clayey hill situated on the top of nevėžis valley. the surface has been changed several times, however a high groundwater was always a big problem for construction activities (bertašius 2011). sources of moisture, worsening the condition of buildings of panemunė and raudonė castles, are not only the pedestals of manor walls covered with excess soil in soviet times when levelling courtyards, but also the culverts of ponds having seen no repairs for a long time, as well as the trees growing close to the manor walls and casting a shadow on the buildings. local communities, used to live in panemunė area, have been disappearing like in other lithuanian villages. with the decreasing number of children the building of raudonė castle will be forced to look for another user. however, the adjustment of high cultural value landscape merely for the purposes of visiting tourism and not for the needs of local community can result not in its revival but in irreversible degradation processes of the cultural value of landscape. 4. conclusions 1. in lithuania, a general methodology for identifying valuable features of historic and cultural landscape has not been yet developed. no consequent studies have been taken to examine the expressiveness of the cultural value of landscape in the dominating regions of lithuanian historic heritage. territorial coherence of the material parts of landscape is considered in several territorial planning documents, however, no fundamental scientific research is currently carried out to study landscape as a mental object. 2. the mid-section of panemunė is a unique representer of two military systems of the 13th–15th century: the aggressive teutonic and the defensive lithuanian. the landscape of the right riverbank section between jurbarkas and kaunas still reflects a distinct semantic and spatial composite interaction of lithuanian defensive castles, their contraposition to the teutonic castles used to be built on the riverbank, and the authenticity of local natural components. those territorial features create in the context of lithuania the exclusive historic and cultural value of the study territory and shall be treated as the essential resource for the development of cultural tourism. 3. at present, the main works of restoration, adjustment and renovation of the mid-section of panemunė are carried 8 out in the residential masonry castles situated in the upper terrace of the nemunas slope: panemunė (gelgaudai, vytėnai), raudonė and raudondvaris castle complexes. the lowest amount of works is being implemented in the ensemble of raudonė castle, the building of the former palace of which is the only castle building used for direct needs of local community. whereas, in panemunė castle, distinguished for its exclusively high architectural and historic value, the currently implemented multi-stage project of its adjustment for tourism needs is not intended for the development of interaction between the castle and the local community and for the strengthening of the castle’s integration into the local social structure. 4. a contraposition of lithuanian and crusader castles and the former tension between them has not been properly represented in the territory. the importance of the territory, as of a unique east european medieval military theatre having personified one and a half hundred years of lithuanian resistance to crusader expansion, has not been emphasized. when forming the territory the insufficient role is given to the forms of local terrain and to the survived defensive structures and their relics. due to insufficient historic and archaeological research the sites of the ancient crusader castles are not unambiguously localised, their supposed sites are not visually emphasized. 5. the current multiple transport and communication infrastructure of the territory (the former samogitian (žemaičių) road, local roads, cycle track (with two operating sections), pedestrian tracks and nemunas river piers) creates preconditions to develop a complicated mental landscape based on a developing plot. by opening the views on the castles from the main observation places, by strengthening spatial relations between lithuanian castles and the sites of the ancient crusader castles and using additional information and interpretation measures the historic and cultural potential of this landscape would be comprehensively disclosed. with rapid changes in the social structure and the system of values of both the tourists and the panemunė region inhabitants it is necessary to seek for the new ways of cognition and propagation of a cultural value of this unique landscape by also involving local communities into the heritage protection processes. references almonaitis v. 2003. vokiečių ordino dubysos pilis. seredžius. vilnius, versmė. bertašius m. 2011. raudondvario dvaro sodyba. in: archeologiniai tyrinėjimai lietuvoje 2011 metais. vilnius, lietuvos archeologijos draugija, 243–246. biliūnas j. 2007. ir rados stebuklas. vilnius, lietuvos rašytojų sąjungos leidykla. burra charter: the australia icomos charter for places of cultural significance. 1999. australia icomos, available at: http://australia.icomos.org/wp-content/uploads/burra_ charter.pdf (accessed 29 march 2013). cleere h. 1995. cultural landscapes as world heritage. conservation and management of archaeological sites, 1(1), 63–6. creighton o. h. 2005. castles and landscapes. power, community and fortification in medieval england. london, equinox publishing. čepaitienė r. 2004. nuo indianos džons iki laros kroft arba kintantis praeities vaidmuo šiandienos pasaulyje. miestų praeitis, 1, 7–41. european landscape convention. 2000. council of europe. available at: http://conventions.coe.int/treaty/commun/ quevoulezvous.asp?nt=176&cm=8&cl=eng (accessed 29 march 2013). fairclough g. 2008. new heritage, an introductory essay people, landscape and change. in fairclough g., harrison r., jameson j. h. jnr., schofied j. the heritage reader. london, routledge, 297–312. fish s. 2008. administration of historical heritage in germany: a national report. in: fish s. national approaches to the governance of historical heritage over time. a comparative report. amsterdam, nld: ios press. jurbarko rajono 2011–2015 metų starteginis plėtros planas (patvirtintas jurbarko rajono savivaldybės tarybos 2010 m. rugsėjo 30 d. sprendimu nr. t2-270). available at: http:// www.jurbarkas.lt/index.php?1517086044 (accessed 29 march 2013). jurbarko rajono savivaldybės teritorijos bendrasis planas, patvirtintas jurbarko rajono savivaldybės tarybos 2008 m. kovo 27 d. sprendimu nr. t2–81, teritorijų planavimo dokumentų registro registracijos nr. 000941000643. kvizikevičius l. 2003. seredžius archeologijos šaltinių duomenimis. in: lietuvos valsčiai. seredžius. vilnius, versmė, 117–124. leach n. 2000. rethinking architecture. london and new york, routledge. lietuvos respublikos kraštovaizdžio politikos krypčių aprašas. žin., 2004, 174–6443, 6 str. lietuvos respublikos nekilnojamojo kultūros paveldo apsaugos įstatymas, žin., 2004, nr. 153–5571. lietuvos respublikos saugomų teritorijų įstatymo pakeitimo įstatymas, žin., 2001 12 28, nr. 108–3902; žin., 2010 06 22, nr. 81–4229. lietuvos respublikos teritorijos bendrasis planas. lr seimo nutarimas nr. ix-1154, 2002 m. spalio 29 d. panemunių regioninio parko tvarkymo planas, patvirtintas lietuvos respublikos aplinkos ministro 2010 m. birželio 14 d. įsakymu nr. d1-499. vaitkevičius g., kiškienė m. l. 2010. kreivasis miestas. 2010. in: miestų praeitis 2, vilnius. lii. zaleckis k. 2011. globalizacijos atspindžiai miesto kūne: keletas įžvalgų. logos, 66, 142–152. received 2013 04 02 accepted after revision 2013 05 22 9 jūratė jurevičienė – researcher, vilnius gediminas technical university, research institute of territory planning. main research area: research in cultural heritage. address: saulėtekio av. 11, vilnius, lithuania. tel.: (8 5) 274 5210 e-mail: jurate.jureviciene@vgtu.lt marija burinskienė – professor, vilnius gediminas technical university, research institute of territory planning. main research area: urban planning. address: saulėtekio av. 11, vilnius, lithuania. tel.: (8 5) 274 4720 e-mail: marija.burinskiene@vgtu.lt journal of sustainable architecture and civil engineering 2022/2/31 96 study of the influence of indoor plants as an indicator of biophilic design on co2 concentrations in a classroom of higher education institute *corresponding author: kavathekar.anita@gmail.com study of the influence of indoor plants as an indicator of biophilic design on co2 concentrations in a classroom of higher education institute received 2022/02/23 accepted after revision 2022/05/04 journal of sustainable architecture and civil engineering vol. 2 / no. 31 / 2022 pp. 96-108 doi 10.5755/j01.sace.31.2.30791 jsace 2/31 http://dx.doi.org/10.5755/j01.sace.31.2.30791 ar. anita k. kavathekar* sinhgad college of architecture, pune 411038 sp pune university maharashtra, india dr. shaila bantanur bms school of architecture, bangalore 560064, visvesvaraya technological university, karnataka 590018, india introduction abstract urbanization in indian metropolitan cities deteriorating the outdoor environment by polluting water, soil, and air to a great extent. some of the cities are at a fatal level of contamination affecting indoor environments. many studies had reported the impact of a high level of co2 indoors on the occupants. its effect depends upon the concentration of co2, the duration of exposure, and the concentration of oxygen (o2). still the effects range from increased respiratory rates to cardiac ailments and carcinoses. india is a developing country so the sustainable and affordable approaches will be more applicable in this context. this study tries to find a well-grounded way to improve indoor air quality. the current pilot study focuses on examining the effect of indoor plants on indoor air quality by measuring co2 levels. this study has used three different species of plants for three different classrooms of higher education institutes. the study was performed in an unsealed environment where air velocity and co2 were measured. statistical analysis results show that indoor co2 concentration has been reduced by 11% than outdoors after placing the plants. this study also shows the correlation between co2 concentration and the distance from the plant using the pearson correlation coefficient. hence indoor vegetation can be considered a sustainable way of purifying the air and altering the microclimate of the classrooms for the well-being of the occupants. keywords: biophilic design, classroom, co2 concentration, indoor air quality, indoor plants. globalization had a great impact on the entire world. it had increased urbanization to a great extent. now it is projected that by 2050, 70 % of the population will live in the cities (browning et al., 2014). for india, it is the most significant phenomenon of the 20th century that has affected all aspects of national life (jaysawal & saha, 2014). this urbanization is limiting access to open green spaces and people cannot explore the outdoors. the design of our physical surroundings, including landscapes and buildings, can have a meaningful impact on psychological states and wellbeing (coburn et al., 2019). people spend almost 90% of their time indoors whether it is a residence or a workspace. urban development is getting congested affecting ventilation around and across the buildings with reduced ventilation rates. thus, urban areas are often associated with 97 journal of sustainable architecture and civil engineering 2022/2/31 poor air quality. in india, pollution emerges from households and ambient air, thereby majority of the population is exposed to indoor and outdoor pollution (bhargava et al., 2021). in the year 2017, the number of deaths due to air pollution (both indoor and outdoor) in india were about 1.2 million (health effects institute 2019). a growing body of scientific study indicates that humans need daily contact with nature to be productive and healthy (downton et al., 2017). so, bringing natural elements indoors (biophilic design) has received increased attention recently due to its potential health benefits, human fitness, and quality of life (yin, 2019; calabrese, 2015). thus, indoor environmental quality and its comfort have an important role to play for the occupants in terms of their physical as well as psychological health. it was observed that the studies based on indoor plants and indoor environmental quality were from places like the netherlands, taiwan, united arab emirates (uae), etc. (mangone et al., 2014; han, 2020; jung & awad, 2021), with significantly different climatic contexts than india. these studies were conducted in a sealed environment where doors and windows were closed and air conditioning was on mode. these sealed environments were representative of the conditions that would be normal for hot or cold regions. the higher education sector in india is expanding at a great rate with 45000-degree colleges and diploma institutes having an enrollment of 25.9 million students (higher education summit, & ernst & young, 2012). with this number, the design and comfort of the indoor environment of the classroom become very crucial. however, the classrooms in india rely majority on the natural light and ventilation. the studies about indoor plants and indoor environmental quality were hardly found in the indian context. hence understanding the impact of plants on the indoor environment in the natural condition where doors and windows were kept open and conducting the study, became important or relevant to the context. this research aims to evaluate the sphere of influence of indoor plants on indoor air quality for carbon dioxide (co2) concentration in a classroom. the objectives of the study were to develop a method of data collection and its validation through the experimental setup for documenting parameters of the indoor environment like co2 concentration and to explore the relationship between measured data of parameters and the position of plants. the hypotheses of this study were as follows: hypothesis 1: plants at different distances and with the same green coverage ratio have different effects on the objective physical environment in terms of air quality such as co2 concentration, there is a correlation between co2 concentration and distance away from the plant. hypothesis 2: plants have affected indoor air quality by reducing indoor co2 concentrations than outdoor co2 concentrations in the classroom. hypothesis 3: all plant species used in the experiment has different ability to absorb the co2 concentration. literature review biophilic design biophilia means the innate affection towards nature and natural elements. innate means hereditary and hence part of ultimate human nature (kellert, 2018). the term was coined by e.o. wilson and further developed by researchers like s. kellert, and browning. these researchers have come up with different dimensions, and patterns of biophilic design. the 14 patterns identified by browning et al. (2014) prioritize the most significant nature-health relationships in the built environment, which are supported by the well building standard rating system. the international well building institute is a public benefit corporation whose mission is to improve human health and wellbeing in buildings and communities across the world. recent studies examining students’ exposure to nature found the amount of vegetation and surroundings of campus significantly predicted school-wide student performance (i.e., standardized test scores, graduate rates) (pan et al., 2014). during their time in classrooms, students are required to focus, absorb information, journal of sustainable architecture and civil engineering 2022/2/31 98 and actively reflect on this information. these tasks, call upon students’ directed attention, and resources, which are susceptible to fatigue (van den bogerd et al., 2020). one study proposes that the inclusion of biophilic elements such as plants, natural landscapes, light, and water in learning spaces, such as classrooms, supports the learning ability and can also generate a sustainable, inspiring, and innovative learning environment (abdelaal, 2019). many studies with different objectives were carried out and found that reduction in health complaints of students by 21% (fjeld, 2000), stress reduction among the students (li & sullivan, 2016), reduction in blood pressure (yin, 2019) when biophilic design attributes used in the classrooms. one study mentions that biophilic design requires repeated and sustained engagement with nature for its continuous benefits (downton et al., 2017). it was found that there is an improvement in cognitive functions, creativity, short-term memory, and the attention capacity of occupants after introducing plants into the built environment (kavathekar & bantanur, 2021). hence, plants were used indoors as one of the indicators of biophilic design for this study. benefits of indoor plants from an evolutionary history aspect, plants were of crucial importance for survival. humans were dependent on plants as a food resource, for shelter, and as an indicator of water. so, on the theoretical ground presence of plants was an integral part of the human environment of evolutionary adaptation (grinde & patil, 2009). kellert argues that visual representations of nature, symbols of nature, nature views, indoor plants, and other natural objects and design elements appeal to this innate affinity and so can evoke positive experiences in the built environment. plants are the most common element of nature and are also often regarded as the most representative of nature. even within a manmade structure, it is true. (hartig et al., 2008). plants used for indoor environments have pleasing aesthetic features, and their associated microbiome has been greatly disregarded (brilli et al., 2018). plants used in workspaces show that the introduction of living plants in individual worktops & breakout has significantly changed perceived health & several performance metrics (attention, creativity, productivity) (hähn et al., 2020). when potted plants were used in learning environments such as classrooms, it was reported that students had greater attention, more positive lecture evaluation (van den bogerd et al., 2020), and good conduct as fewer punishments for misbehavior (han, 2009) (bringslimark et al., 2009). indoor plants are used for psychological as well as physiological well-being for their ability to clean air. during photosynthesis, plants take in more co2 through their stomata, they also absorb contaminants. a diverse range of indoor air pollutants can be phyto-remediated with the help of potted plants. absorption of co2 releasing of o2 is also dependent on the amount of natural or artificial light, the leaf area of the plant (park et al., 2010). temperature influences the voc emission from building materials along with air velocity and humidity. similarly, relative humidity affects the emission of formaldehyde in particleboard. hence plants not only clean air by the process of photosynthesis and phytoremediation but also can control temperature and relative humidity which can control the airborne pollutants (aini jasmin et al., 2012a). some studies showed that after placing the plants indoors co2 levels were increased and got stabilized (jung & awad, 2021; h. kim et al., 2016; smith & pitt, 2011) whereas few studies noted a continuous decreasing trend (bhargava et al., 2021; pamonpol et al., 2020; pegas et al., 2012). plants help achieve thermal comfort and it was observed that the effect of plants on thermal comfort was not reduced overtime or by season (mangone et al., 2014). it was noticed that continuous reduction in sick building syndrome (h. h. kim et al., 2013) and ocular discomfort symptoms (h. kim et al., 2016) with plant interventions. however, it was seen in the review paper (han & ruan, 2020) that, only 18.75% were field experiments conducted in living environments, whereas 76.04% were conducted using laboratory experiments, of which 66.34% were performed in small fumigation chambers. therefore, 99 journal of sustainable architecture and civil engineering 2022/2/31 whether the results of these studies can be directly generalized or applied to actual life situations is yet to be determined. for instance, pollutant concentrations and volatilization rates in fumigation chambers are typically higher than those in actual environments. however, such studies were hardly found in the unsealed environment in the indian context. the study also states that the capacity of the indoor plants in removing air pollutants needs to be quantitatively assessed in realistic scenarios (brilli et al., 2018). hence the study is conducted in the actual classroom with live settings. indoor air quality (iaq) indoor environmental comfort was categorized into visual, thermal, acoustical comfort, and air quality (mujan et al., 2019). whilst poor air quality remains a global issue (world health organization 2014). indoor air pollution has become a major concern in india in recent past years. numerous epidemiological studies have demonstrated associations between pollutants in outdoor air (primarily pm10, pm2.5, and ozone) and both morbidity (illness) and mortality (death) (sundell et al., 2011). air composed of 21% o2 and 0.033% co2 taken in by people from the normal atmosphere becomes 16-17% o2 and 4% co2 content during discharge from the lungs. this change leads to a rapid rise in co2 content in environments like schools, shopping malls, and hospitals, where people tend to congregate. co2 concentration is currently adopted as a key parameter for ventilation and iaq evaluation. almeida (almeida et al., 2017) explains through literature, how co2 is an important parameter while studying iaq. co2 is the most used indicator of ventilation efficiency since it is a product of respiration and school and college buildings typically maintain high levels of occupancy during large periods of the day. co2 has been reported to cause breathing problems, inattentiveness, and headaches (almeida et al., 2017). although it does not harm the human body by itself, an increase in its concentration often indicates a deterioration in thermal conditions or an increase in other pollutants. increased co2 levels were found to reduce short-term students’ attention performance in experimental studies with 20 cluster-randomized classrooms in germany and 51 primary schools in portugal (pulimeno et al., 2020). one study in scotland has observed that an increase in co2 concentration of 100 ppm was associated with 0.4 days of missed school per child per year. the same study mentioned that despite of differences in climate and method of classroom ventilation, there was consistency in results for increased indoor co2 concentration in school was an important public health issue (gaihre et al., 2014). how to sustain good iaq with low energy consumption is an important aspect of designing the built environment (pamonpol et al., 2020). considering the exponential growth of higher education institutes in india, this study aimed to analyse the effect of indoor plants on improving the iaq while focusing on co2 in the classroom. methods and materials to find out the effect of indoor plants on indoor air quality in terms of co2 concentration the field experiment was carried out in a classroom of an educational institute. a pilot study started in november 2021 and it still going on as a long-term research project for the author. experiment methodology design assumptions and limitations the selection of instruments was based on literature study, accuracy limits, indian society of heating, refrigerating, and air conditioning engineers (ishare) standards, and economical constraints. the study presented in the paper was a pilot study so the experiment was focused on the co2 concentration of three classrooms with three types of species. it was assumed that the quality of air due to the plant effect will be changing as pollutants in actual space in natural ventilation mode do not maintain constant concentration. similarly, the study has considered the plants, potting soil, and container as a whole unit. so, the influence of plants, potting soil, and the container was not seen differently. journal of sustainable architecture and civil engineering 2022/2/31 100 pilot case experiment building description the chosen institutional building is established in the mid-nineties and is situated in the core city. the building was abutting a busy road. building construction material was an rcc structure with 0.23 m partition walls of burnt bricks, flooring of mosaic tiles, door and windows were of teak wood with paint finish. surface finishes were cement plaster, and walls and ceiling were painted with distemper paints one decade back. the classroom has furniture like student tables (mild steel), stools (wood (varnished) and mild steel (oil painted)), teacher tables (wood and laminated ply), and soft boards with jute-based fabric covering. tabletops for students were of pinewood and three years old, storage cabinets were kept of oil painted mild steel. environmental parameter measurement methodology the selected classrooms were of the same area and volume. the area of the classrooms was a 76 sq.m. area. the rooms were divided into a ten-point grid to form approximately equal ten parts of the room. now, the centre of each part is a measuring point for data collection. air velocity and co2 concentration were measured at all these points with the instruments mentioned in table 1. this study was conducted in the winter season (november and december). the outdoor temperature was 23-24 ℃, so the indoor temperature was within comfort conditions as per mentioned by the (ishare). few research studies mentioned data collection point one, readings were taken at the centre (shree et al., 2019a; shree et al., 2019b; jung & awad, 2021) or only two points depending upon occupancy and plant position (kim et al., 2013; han, 2019; 2020) but the current study had collected data uniformly throughout the classroom. similarly, the study by bhargava et al. (2021) sr. no. environmental parameter instrument specification cronbach alpha (reliability test of the instruments) 1 carbon dioxide lutron co2 meter gch 2018 range 0 4000 ppm resolution 1ppm accuracy ± 40 ppm ≤ 1000 ppm 0.999 2 air velocity hotwire anemometer lutron am-4204 measurement: m/s range 0.2 20.0m/s resolution 0.1 m/s accuracy ± 5% +1d 0.972 fig. 1 sketch and image of the classroom showing plants at the center table 1 list of instruments used for experiments for different parameters mentioned the readings taken by moving the instrument around the room (bhargava et al., 2021). whereas the current study mentioned systematic arrangements of data collection points. the literature study documented the frequency of reading thrice a week (kim et al., 2013) with nine readings, and the second was with continuous reading with data loggers, the frequency was every 6 min., 30 data points were recorded (han, 2019). for this study frequency of reading was one per week and a total of six readings were measured. as this was a pilot project, methods tested in this experiment will be applied to a greater extent in the form of a long-term project. during the data collection, all the windows and doors were 101 journal of sustainable architecture and civil engineering 2022/2/31 open whereas artificial lights and fans were switched off. for the study duration growth of the plants was not considered as these plants were slow-growing plants. for the long duration study, the growth of the plant would be considered as one of the parameters. readings were taken in the non-occupancy mode because of pandemic conditions (lockdown due to covid-19 restriction). an equal number of plants were kept in three classrooms referring to table 2. green coverage ratio diameter of plant/pot no. of plants 6 0.45 0.6 m 14 5 0.45 0.6 m 11 4 0.45 0.6 m 9 3 0.45 0.6 m 7 2 0.45 0.6 m 5 table 2 shows the green coverage ratio and number of plants a previous study by han (2019) states that installing one large potted plant and one small potted plant per 6 m2 floor area in a room whereas us studies have also recommended placing at least one (15.24 cm) potted plant per 9 m2 floor area in a room was sufficient to clean air (han, 2019). the green coverage ratio was derived from the literature study (han, 2009; 2019; 2020). based on the literature study, plant requirement for air quality was developed for a 100 sq.m. area which is dependent upon the diameter of the plant. whereas the study by bhargava et al. (2021) had not mentioned the relation between room area and the number of plants placed for the experiments (bhargava et al., 2021). the selection of the plant species was based on pollutants that can be removed, dimension, daylight/ shade tolerant, sustained to temperature variation, vulnerability to pests & diseases, and maintenance (han, 2009). plants were selected as per table 3. ten numbers of each, rhapis excelsa (lady palm), areca palm, and dracaena reflexa (song of india) were placed in three different classrooms. the plants were kept in the centre of the classrooms which coincides with one of the data collection points. plants were of 0.45-0.50 m diameter mean foliage and 1.1 m in height. the plants kept in the class were in healthy condition and were in nursery bags only. soil is nursey red soil and during the entire experiment, no fertilizers and pesticides were applied to the plants. image name rhapis excelsa (lady palm) areca palm dracaena reflexa (song of india) plant dimension dia.0.55 ht.1.1 dia.0.45 ht.0.9 dia.0.55 ht.1.0m daylight/ shade tolerant very tolerant of shade and dry air prefer a part-shade setting need indirect light and warm temperatures sustained temperature variation 16-27 °c 18-25°c 19-24°c maintenance only feed the plant once a year easy to grow and maintain it is relatively easy to care pollutants that can be removed formaldehyde, ammonia, and xylene benzene, carbon monoxide, formaldehyde, trichloroethylene, xylene xylene, trichloroethylene, and formaldehyde (green planner, n.d.) table 3 details of selected plant species journal of sustainable architecture and civil engineering 2022/2/31 102 empirical readings readings were taken before placing the plants. the next sets were done after one week and the frequency of the readings was per week. data was collected to each grid point at the 0.9 m level. this was the breathing zone when students were in the seating position. as mentioned above, while taking measurements doors and windows were kept open. readings of the immediate outdoor were also taken at the same time to have parity. while taking the reading average indoor air velocity was ranging from 0.00 to 0.07 m/s. statistical analysis the purpose of the study was to understand the sphere of the influence of the plant on the quality of air. so, the data has been compiled for six weeks. the collected data passed the normality test and then the mean was taken for each data point. to find out the correlation, the point where plants were kept was considered as the reference point. considering that as a reference, the co2 concentration of all other points was plotted against the distance and was arranged in an increased order. the statistical analyses were conducted using ibm spss 28.0. to understand the correlation between co2 concentration and the distance from the plant, pearson correlation coefficient was used. to find out the difference between the indoor and outdoor co2 concentrations, an independent t-test was used as the samples were independent. one-way anova was used to compare the co2 concentration absorption ability of three species. rhapis areca song of india 0.00 2.00 4.00 6.00 0.00 10.00 20.00 30.00 40.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 0.00 2.00 4.00 6.00 0.00 10.00 20.00 30.00 40.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 0.00 2.00 4.00 6.00 0.00 20.00 40.00 60.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 0.00 2.00 4.00 6.00 0.00 10.00 20.00 30.00 40.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 0.00 2.00 4.00 6.00 0.00 10.00 20.00 30.00 40.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 0.00 2.00 4.00 6.00 0.00 20.00 40.00 60.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 0.00 2.00 4.00 6.00 0.00 10.00 20.00 30.00 40.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 0.00 2.00 4.00 6.00 0.00 10.00 20.00 30.00 40.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 0.00 2.00 4.00 6.00 0.00 20.00 40.00 60.00 d is ta nc e (m ) increased co2 in ppm scatter plot of distance vs increased co2 results plant effect on indoor co2 concentration with respect to distance hypothesis 1: there is a correlation between co2 concentration and the distance away from the plant. the scatter plots of three plants in table 4 show the relation between distance and increased co2 concentration still, statistical tests were performed to find the level of significance for the same. to test the first hypothesis, pearson’s correlation coefficient was found for three species shown in table 5. table 4 the scatter plot shows the relationship between distance vs co2 concentration table 5 pearson correlation coefficient for three species rhapis areca song of india correlations distance increased co2 (ppm) distance increased co2 (ppm) distance increased co2 (ppm) pearson correlation 1 .823** pearson correlation 1 .769** pearson correlation 1 .573 sig. (2-tailed) .003 sig. (2-tailed) .003 sig. (2-tailed) .084 **. correlation is significant at the 0.01 level (2-tailed). **. correlation is significant at the 0.01 level (2-tailed). 103 journal of sustainable architecture and civil engineering 2022/2/31 to find out the correlation between co2 concentration and distance from the plant, pearson correlation was used after performing a normality test on data. the pearson correlation coefficient shown in table 5 between distance and increased co2 concentration is 0.823, 0.769 significance at the 0.01 level, for rhapis and areca respectively. for song of india plants, it was 0.573. data were analysed for linear regression to find out the strength of the model as shown in table 6. the values of r and squared r were promising for rhapis and areca, 0.823, 0.839 (r2), and 0.677, 0.704 (r2) with a p-value of 0.003 and 0.001 respectively. while song of india shows a low r-value with no statistical significance. the unstandardised predicted value was found in linear regression and plotted on a scatter plot along with the original values. the model was checked for its goodness of fit. scatter plots in fig. 2 show that the observed values and unstructured values were coincides closely with rhapis, areca, and song of india. while for rhapis, and song of india it was getting apart after 5.5m. whereas for areca data points coincide with predicated values even after 6.0m. plant r r2 durbin-watson f sig. rhapis 0.823 0.677 1.12 16.77 0.003 areca 0.839 0.704 1.964 21.407 0.001 song of india 0.593 0.352 0.623 4.345 0.710 table 6 linear regression data analysis to find out the strength of the model fig. 2 scatter plot of the predicted value of increased co2 concentration by distance rhapis areca song of india page 1 of 1 rhapis areca song of india page 1 of 1 rhapis areca song of india page 1 of 1 rhapis areca song of india journal of sustainable architecture and civil engineering 2022/2/31 104 comparison of indoor and outdoor co2 concentration hypothesis 2: plants have affected indoor air quality by reducing indoor co2 concentrations than outdoor co2 concentrations in the classroom. the performance of the mentioned three species was compared to how much indoor co2 concentration is less than outdoors. data were tested for their normality and an independent t-test was used to compare. as the data was not paired and the comparison was between two sets, an independent t-test was used. as the difference was checked for either more or less hence significance of one-sided p was considered. one-sided p values for rhapis (0.004) and song of india (0.022) were less than 0.05 whereas for areca it is 0.05 as per table 7. sig. t df significance one-sided p two-sided p avg_102_ rhapis .012 -3.357 10 .004 .007 avg.co2_203_areca .014 -1.807 10 .050 .101 avg_202_ song of india .236 -2.304 10 .022 .044 table 7 results independent t-test of three species comparing indoor and outdoor co2 concentrations comparison of ability to absorb co2 of three species hypothesis 3: all plant species used in the experiment has different ability to absorb the co2. three species were compared for their ability to absorb carbon dioxide. as data had passed the statistical normality test, one way anova test was used as the data was not paired and there were more than two data sets. results were shown in table 8. it was found that all p values were greater than 0.05. (i) var00013 (j) var00013 mean difference (i-j) sig. rhapis areca -12.27500 .575 song of india .35000 1.000 areca rhapis 12.27500 .575 song of india 12.62500 .553 song of india rhapis -.35000 1.000 areca -12.62500 .553 table 8 result of one-way anova comparing performance in terms of absorbing co2 concentration of three species discussion hypothesis 1(there is a correlation between co2 concentration and the distance away from the plant) gets supported for rhapis and areca plants. rhapis and areca plants indicate a positive correlation between distance and increased co2 concentration is significant at a 1% level. whereas the third plant song of india did not show the significance level. so, hypothesis 1 was partially supported. it shows that as one moves away from the plants, the co2 concentration was increasing. while studying the plants and air quality, han (han, 2019) observed that the co2 concentration was higher near the plant regardless of the number of plants. in the current study, the green coverage ratio is constant but the correlation with distance is significant for the two species. co2 concentration has increased away from the plant which contradicts to literature. han experimented with almost sealed environments hence direct comparison may not be appropriate. even han (han, 2019) had also checked the effect of plants at 1.5 and 3.0 m distances. table 6 showed the r-value measures 105 journal of sustainable architecture and civil engineering 2022/2/31 the degree of relationship between the actual values and the predicted values of the increased co2 concentrations. the coefficient value (r) of 0.823, 0.839 for rhapis and areca, indicates that the relationship between distance and the increased co2 concentrations is quite strong and positive. thus, the value of r square is 0.677, 0.704 means that about 67.70% and 70.4% of the variation in co2 concentrations is explained by the estimated simple regression that uses distance as the independent variable and the r square value is significant at 3% and 1 % level for rhapis and areca respectively. the scatter plots in fig. 2 showed that the model was working efficiently till 5.5m for rhapis and song of india plants while for areca it would work for more than 6.0m. this means the influence of these plants could work 5.0-6.0 m range. so, in a classroom plant can be placed at the mentioned distance for improved air quality. however, the study by the researcher mentioned that irrespective of the green coverage ratio and distance from the plant, co2 was significantly greater in the presence of indoor plants than in the absence of indoor plants (han, 2019). hypothesis 2 (plants have affected indoor air quality by reducing indoor co2 concentrations than outdoor co2 concentrations in the classroom) gets supported. the results of table 7 indicate that the absorbing capacity of rhapis, areca, and song of india is significant concerning outdoor co2 concentration with a one-sided p-value of 0.004, 0.050, and 0.022 respectively. hence the hypothesis got accepted. the indoor co2 is significantly less than outdoor. for the areca plant, a one-sided p-value is 0.005 which is on the border. so, it needed further investigation to confirm the results. while the study by bhargava et al. (2021) found that with the increase of areca palm plants from three to nine, a reduction in the co2 level was recorded from 10.2% to 44.76% in respective experimental rooms (bhargava et al., 2021). hypothesis 3 (all plant species used in the experiment has different ability to absorb the) is tested with the anova test. while comparing these three species as shown in table 8, in terms of absorbing the capacity of co2 amongst these three, the p-value for all these species was more than 0.05. so, the hypothesis gets rejected. it has been noted that all three species perform equally. the results of the current study corroborate with the study by aini jasmin et al. (2012) where rhapis and dracaena species were used in a similar experimental room as mentioned here. as per the current study, the co2 absorption ability of the rhapis plant was better than song of india, and song of india was better than areca. the results coincide with the other studies for rhapis but not for the areca plant for co2 absorption ability. the study observed that the areca palm had a better co2 absorption capacity (jung & awad, 2021; kulkarni & zambare, 2018). the study explains the effect of the indoor plant on the physical environment. this research has also observed the co2 absorption ability of different plant species although the classrooms have the same area and volume and the number of plants was also the same. from the current study, it can be inferred that for improved air quality, plants can be kept at a 5.0-6.0 m distance. the findings of this study have bridged the gap in research regarding the conducting unsealed environment instead of enclosed fumigation chambers and sealed environments. the study has contributed to finding the correlation of change in co2 concentration with respect to distance away from the plant. the findings will be applicable in terms of quantification of green coverage ratio to distance for improving the air quality of the classrooms where the occupancy is high for a longer time. in the indian context, such a method has not yet been used for unsealed rooms. this is an energy-free method for regulating indoor air quality and immediate surroundings. future scope as the current study is a pilot study, further investigation will help to find more robust findings. further study could be conducted in a regular working classroom by placing indoor plants in a classroom and studying objective thermal comfort and subjective visual comfort. conclusion journal of sustainable architecture and civil engineering 2022/2/31 106 references acknowledgment we thank dr. sachin adnaik for his help in statistical analysis. we also thank the principal sir and the teaching and non-teaching staff of the institute for their support and co-operation. abdelaal, m. s. 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(2019). bringing nature indoors with virtual reality: human responses to biophilic design in buildings [harvard university]. https://doi.org/http:// nrs.harvard.edu/urn-3:hul.instrepos:42013069 journal of sustainable architecture and civil engineering 2022/2/31 108 this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). about the authors ar. anita k. kavathekar associate professor sinhgad college of architecture, pune411038 sp pune university maharashtra, india main research area biophilic design, indoor environmental quality, built environment, architectural design theory. address pune, maharashtra tel.: 9881720569 e-mail: kavathekar.anita@gmail.com dr. shaila bantanur director and professor bms school of architecture, bangalore 560064 main research area sustainability practices and awareness in rural areas, lighting analysis in rural areas, sustainability and green buildings. address avalahalli, doddaballapur main road, yelahanka, bengaluru – 560064 tel.: 8978577592 e-mail: shailabunty@gmail.com journal of sustainable architecture and civil engineering 2022/1/30 50 *corresponding author: bemanian@modares.ac.ir role of the architectural application of nature in improving the quality of semantic depth in iranian urban housingreceived 2021/12/09 accepted after revision 2022/02/10 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 50-64 doi 10.5755/j01.sace.30.1.30226 role of the architectural application of nature in improving the quality of semantic depth in iranian urban housing jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.30226 mohammadhossein azizibabani ph.d. student in architecture, department of architecture, faculty of arts, tarbiat modares university, tehran, iran. mohammadreza bemanian professor at the department of architecture, faculty of arts, tarbiat modares university, tehran, iran. introduction abstract the purpose of this study is to investigate the effects of the architectural application of nature’s (aan) components in improving the quality of semantic depth in iranian urban housing to determine the most effective architectural indicators in this context. this research uses a mixed methodology in terms of the data’s nature, and the research method is descriptive-analytical (causal and comparative). the components and indicators related to the aan have been collected through the study of theoretical foundations and literature review. to determine the relationship between these components and the semantic depth variable in housing design, the method of logical reasoning has been employed. data were collected through a questionnaire with the participation of 96 occupants of phase 1 of ekbatan residential town, to determine the perceived quality of research variables. the results of regression analysis on quantitative data confirm the research hypothesis regarding the key role of maintaining the principle of spatial hierarchy in increasing the possibility of understanding the semantic layers in housing that most of them exist due to the presence of various manifestations of nature. keywords: architectural application of nature, semantic depth, spatial hierarchy, qualitative aspects of nature, iranian urban housing. nature has always been the context of human activities, and the construction of any kind of buildings that aims to meet human needs and expectations always requires touching nature and contemplating the threefold relationship between man, nature, and architecture. this relationship depends on the position of nature and its related components in the worldview, culture, and lifestyle of society. there is also an obvious interaction between the architecture form and content with nature. concerning the development of human settlements, the two approaches of overcoming nature or interacting with it are more theoretically discussed. the first approach whose intellectual roots date back to the late renaissance considers nature as a mechanism whose order is mechanical (nasr, 1996). according to this view, architecture operates using a human-centered approach 51 journal of sustainable architecture and civil engineering 2022/1/30 to overcoming nature, regardless of the limitations and potentials of the context and relying on technology capabilities. the basis of the second approach is taking advantage of the potentials of nature to provide the proper conditions for human comfort (noghrekar, 2013). in this regard, iranian architects have succeeded in creating an environment conducive to human habitation in harsh climates by making proper use of the capabilities of the earth and elements such as water, wind, plants, knowledge of the principles of shading, and understanding the properties of natural elements and materials. the difference between a house and a shelter is providing the necessities to meet the psychological and spiritual needs of man along with his material needs. therefore, housing is not a purely functional subject and the presence of semantic layers in its spaces is effective in meeting human high-levels needs. nature has always been respected from the perspective of the monotheistic worldview and islamic culture that prevails in iranian society, and it is a sacred thing that has been considered as a sign of the presence of god. therefore, from the perspective of iranian-islamic culture, the application of natural elements or their dominated rules and qualities in architectural design can be an important factor in inducing implicit and explicit concepts and values through creating semantic layers in housing design and this process ultimately leads to improved quality of semantic depth in housing design. in this regard, nature appears in the architecture of traditional iranian houses, sometimes as objective forms and sometimes as qualities derived from the conceptual, functional, and formal features of natural elements. but in new types of urban housing, especially apartment complexes, there are many restrictions on direct contact with nature in the interior of the residential units. this shows the importance of landscape design in open spaces of these complexes and the application of subjective qualities derived from nature and its objective aspects. in other words, it can be acknowledged that the architectural application of nature (aan) creates the main semantic layers of the house, which in their absence, a house has no different from a shelter. therefore, this study was conducted to investigate the effects of the aan’s components on improving the quality of semantic depth in iranian urban housing to present practical strategies in new types of urban housing. in this regard, the following questions are raised: what components of aan affect the quality of semantic depth in iranian urban housing? what is the mechanism of the effects of these components in improving the quality of semantic depth? theoretical foundations and literature review nature is the source of responding to human physical and spiritual needs and inspires him in his creations and initiatives. the relationship between architecture and nature, generally, can be investigated in three periods: pre-modern, modern, and postmodern. the general concept of nature in the pre-modern era was known as the origin and essence of things. in this context, the cosmic character of nature has taken precedence over its terrestrial character (falahat & shahidi, 2010). after the industrial revolution and the advancement of technology and the prevalence of humanist thought, especially in western societies, the concept of nature was considered equivalent to the whole material world, which includes all beings and resources needed for industrial development. in this view, nature has been dominated by man to meet his material needs and functionalism has been the dominant aspect of architecture. the purpose of architecture was limited to meeting the material and in some cases the psychological human needs. in the postmodern era, ecosystems and the type of relationship between living things and the environment were considered by architects, the result of which was the emergence of concepts such as sustainability, climatic architecture, eco-architecture, biophilic design, and so on. during this period, technology sided with nature to resolve the crisis of modernist thoughts. among these concepts, the biophilic design which is based on the biophilia theory was developed and adapted within the architectural domain, at the beginning of the 21st century (zhong, schroder, & bekkering, in press). based on the biophilia hypothesis by wilson (1984;1993) biophilia is ‘the innately emotional affiliation of human beings journal of sustainable architecture and civil engineering 2022/1/30 52 to other living organisms.’ after humans migrated to the built environment, we inherited a need for nature, which evolved into ‘thinking about nature’. kellert (1993;2008) defines biophilia values as ‘utilitarian, naturalistic, scientific, aesthetic, symbolic, humanistic, moralistic, dominionistic, and negativistic’. he also defines biophilic design as ‘a deliberate attempt to satisfy the need of contact with natural systems and processes in the contemporary built environment, and to improve people’s physical and mental health, productivity and wellbeing’. the development of any kind of human settlement requires concentrating on the threefold relationship between man, nature, and architecture. gruter (1987) categorizes three practical approaches to these relationships. in his view, in the schools of thought of nature opposition, man and nature have no relation with the supernatural world, and the goal of man during his presence in this world is only the material exploitation of nature to meet the needs of his material dimension. the objective manifestation of such an approach in architecture is mainly related to the architectural developments after the industrial revolution and the period of modern architecture. nature disparity schools of thought have sought to humanize nature. from the viewpoint of these schools, man and nature have two completely different essences. therefore, the main strategy in architecture has been to separate man from nature. in naturalistic schools of thought, the main approach is to naturalize man. from the viewpoint of these schools, any transcendental realm is within this nature, and the only way to reach it is to conform to nature. the view of naturalism has existed in eastern schools for a long time, but a kind of formal naturalism can also be sought in the form of organic architecture in the west. the main difference between eastern and western schools of thought in this area is the general view of god. in the eastern schools, nature is a sacred thing and their status has risen to the level of divinity and in some cases, they turn to the worship of nature. but in western naturalistic schools of thought, the dignity of divinity is diminished and the gods are equivalent to nature. noghrekar (2013) confirms this classification and introduces nature making schools of thought on the relationship between man, nature, and architecture. in these schools of thought, which are in line with the iranian-islamic culture, nature is a part of man and acquires its identity from him, but both have a divine essence. numerous studies have examined the role of nature and its related elements in iranian architecture. afshari basir et al (2017) have investigated the presence of water, plant, and light elements in traditional houses in yazd and concluded that these buildings are designed concerning nature. adeli (2013), outlines two fundamental principles of human and nature’s intrinsic unity and human perfectionism about the human-nature relationship within the framework of islamic ontology. daneshjoo et al (2015) have concluded that the use of natural-based materials and natural forms has had the greatest impact on how to tend to nature in contemporary iranian architecture. keramati (2007) believes that nowadays the component of nature in architecture is so poor so that the triple relation of man, nature, and architecture is unrecognizable. daeipour (2014) believes that nature’s presence plays a positive role in gaining a sense of place in traditional iranian houses which is due to the ability to activate human sensory, activity, and semantic perceptions. mehdi nejad et al. (2012) believe that it is not planned for the beauty of nature and the reason for this beauty is the correct response to the performance that converts natural beauty into an intrinsic and unconscious feature and they propose to pay attention to the geometry in the natural elements to enjoy this kind of beauty. khakzand and ahmadi (2007) believe that the presence of nature’s spirit in architecture leads to its promotion. mamani et al. (2018), believe that the principles of iranian architecture are derived from a rational logic and these principles are found in nature as a divine creation so any artifact that is compatible with these principles is committed to nature and god and respects human beings and human reason. the position of nature from the perspective of iranian islamic culture and the review of literature is evidence that the presence of various manifestations of nature is an important factor in improving the quality of semantic depth in housing design. but architectural subtleties play an important role 53 journal of sustainable architecture and civil engineering 2022/1/30 in inducing these meanings, therefore, investigation of the presence of nature in the architecture of traditional iranian houses can be effective in finding the components of the aan and related indicators to improve the quality of semantic depth in new species of urban housing. semantic components of the architectural application of nature the presence of nature in iranian architecture, especially in the residential environment, has always been either in the form of objective elements or qualities, laws, or institutional mechanisms of nature. these items, which in this research were called “architectural application of nature’s components”, can be classified based on their representative indicators in architecture in the form of three formal, conceptual, and functional factors. the first component that its indicators mainly appear in the architectural forms is unity. the unity of nature idea is a strong metatheoretical theme in several scientific and environmental fields and the reason of adaptation this idea to these fields is to give rise to an inspiring, optimistic, socially-responsive, and environmentally-friendly worldview (marshall, 1999). leibniz believes that monads, as inseparable components in nature, have unity. according to this view, the universe is an organized system in which infinite types of monads have been combined to create a harmonious whole (copleston, 1993). therefore, the quality of unity is present in almost all natural systems and elements, also based on the position of nature in iranian islamic culture, its use in architecture refers to the oneness of god. transparency is another semantic component related to the aan which its architectural indicators are reflected in the form, space structure, and details. transparency and the absence of clear boundaries are obvious features in most natural landscapes. also, the presence of water and light in the traditional houses of iran is one of the primary priorities, which is a manifestation of transparency and purity. there are basically two ways of transparency in architecture; literal transparency indicates how clear the visual boundary between the interior and the exterior space is, and phenomenal transparency which defines a type of architectural organization and is seen spatially in the form of ambiguity and uncertainty in spatial boundaries. the most prominent feature of this organization is that it is possible to have a simultaneous perception of different spatial locations, just as the metaphorical meaning of the term (easy to perceive or detect) indicates (rowe & slutzky, 1963). honesty is considered one of the greatest moral virtues and an attribute of the essence of god. since nature is one of the manifestations of god in iranian culture, therefore, it is free from all lies. the indicators of this quality in architecture are mainly related to the materials, static, and the functionality of the building’s elements. a true architecture can be defined when the intention and spaces truly serve the function they simply should. the main point is to allow the building to speak of its nature and intention through the materials used, spaces designed or the structure built (harries, 1984). hierarchy is one of the principles governing natural collections, components, and phenomena. the existence of beings is a function of a defined hierarchy whose undeniable role in defining the components of a collection and identifying them is important. hierarchical order defines the position and value of each component of a whole as well as the value of a whole individually and relative to other collections (naghizadeh, 2012). types of hierarchies in the man-made environment can be divided into two categories: legal and real hierarchies. the dimensions of the hierarchy can also be divided into neighborhood, functional, transit, and spatial hierarchy, which the last one is so important in iranian traditional houses and is related to the principles of privacy and introversion. in addition to these four components, due to the position of nature in iranian islamic culture, the presence of objective forms of nature can also enhance the semantic depth in housing design. nature’s objective presence has always been observed in iranian architecture in three appearances of primary, secondary, and abstract. primary nature’s appearance refers to the concept of nature journal of sustainable architecture and civil engineering 2022/1/30 54 that has not been transformed by man (spirn, 2000, p. 41). in this regard, the possibility of visual relation with the sky, benefiting from sunshine, wind, planting, and the presence of water in the central courtyard can be mentioned as indicators of the primary appearance of nature in iranian architecture. the abstract appearance of nature is mainly manifested in the form of patterns and abstract forms of natural elements in the decorations or form of the building components. although the relationship with the primary and abstract appearance of nature in architecture is effective in providing suitable climatic conditions and increasing the quality of sensory beauty. but due to the cultural context and the symbolic role of natural elements, the application of these components can also enhance the semantic depth in architecture. aan’s components are not the only factors that promote semantic depth in residential environments, and this is highly dependent on the mental background of the target community, which originates from cultural and social contexts. but in this study, considering the position of nature in iranian culture and the symbolic role of natural elements, the objective forms of the presence of nature in architecture including primary and abstract appearance along with qualities such as unity, transparency, honesty, and hierarchy were considered as the semantic components of the aan. each of these components, depending on how they are used, can be effective in improving the quality of semantic depth in architecture from the perspective of the worldview and cultural context of the target community. indicators related to these components which have been collected through literature review are presented in table 1. table 1 indicators related to the semantic components of the aan c o m po ne nt s indicators descriptions and figures source u ni ty modular design fig. 1. modular system in an iranian traditional house (pirnia m. , 1992) holistic approach (harmony with urban fabric in terms of orientation, building materials, full and empty spaces, and so on ) fig. 2. historical context of yazd (vincent, 2014) using logical, numerical and geometric proportions fig. 3. application of the enclosed rectangle in a regular hexagon in the proportions of traditional iranian houses (hejazi, 2009) similar proportions in decorations and geometric structure fig. 4. the yard enclosure is a constructor of dividing lines tabatabai’s house in kashan (ansari & ebrahimi, 2010) 55 journal of sustainable architecture and civil engineering 2022/1/30 c o m po ne nt s indicators descriptions and figures source tr an sp ar en cy mass reduction due to the dominance of space over mass (embedding the central courtyard and so on) fig. 5. the transparency created by the installation of the central courtyard and the permeability of the wallsgolshan house in yazd (noghrekar, 2008) (mazaheri, dezhdar, & mousavi, 2018) (momeni, 2018) visual continuity due to the sequence of spaces and the permeability of the walls use of reflection phenomena and translucent openings fig. 6. tabatabai’s house in kashan h on es ty compatibility of the facade and its backspaces fig. 7. method of transfer of forces in the structure of an iranian traditional house authors using functional components in the building (pirnia, 1997) demonstrating the transfer of forces in the structure of building properly and the use of self-static forms and materials (bemanian & amini, 2011) using primary color and texture of natural materials authors h ie ra rc hy functional and visual separation of different areas outside and inside the house fig. 8. real hierarchy (a) and customary hierarchy (b) (shia, 2007) (tabibian, charbgoo, & abdolahimehr, 2012) customary separation of areas on the way to the house avoiding indoor visibility from outside fig. 9. avoiding indoor visibility from outside in an iranian traditional house journal of sustainable architecture and civil engineering 2022/1/30 56 research methodology the investigation of theoretical foundations and review of the literature shows that the presence of objective examples of nature besides the adaptation of nature’s qualities and laws in architecture has been the main factor in promoting semantic depth in the traditional iranian houses. the presence of the primary and abstract appearance of nature, in addition to the functions related to the regulation of environmental conditions and aesthetics, also have a semantic burden due to the symbolic role of the natural elements. the qualities of honesty, transparency, unity, and hierarchy, regardless of their effects on functionalism, formal aesthetics, and maintaining privacy in the iranian houses, also include spiritual concepts. the important point is to create the necessary context to understand these semantic layers. therefore, it is hypothesized that observing the principle of spatial hierarchy, considering its effects on increasing the privacy of housing, provides the necessary basis for mental preparation and the possibility of personal privacy and thinking about the semantic layers of housing which large amounts of them are created by improving the quality of applying the primary appearance of nature. therefore, it is hypothesized that the application of the principle of the spatial hierarchy will have the greatest role in improving the quality of semantic depth in housing. this research uses a mixed methodology in terms of the data’s nature, and the research method is descriptive-analytical (causal and comparative). semantic components of the aan and their related indicators were collected through reviewing the literature using the qualitative content analysis method. the perceived qualities of these components are considered as independent variables of research which the perceived quality of semantic depth in housing is a dependent variable on them. to investigate the relationship between these variables a survey was conducted in phase 1 of ekbatan residential town in tehran. in this regard, the results of the authors’ observations on recognizing the indicators related to the research variables were provided to the residents in the form of photos or architectural drawings along with a questionnaire.the questionnaire consists of 29 questions. six of which relate to the socio-demographic variables including age, sex, education, marital status, residence history, and ownership status. nineteen questions relate to determining the perceived qualities of the indicators of dependent variables (the components of aan), and four questions relate to determining the perceived c o m po ne nt s indicators descriptions and figures source p ri m ar y ap pe ar an ce communicating with the sky, surrounding landscapes and natural elements fig. 10. appropriate proportions for visual communication with the skyplacing pool, trees and wind catcher in the central courtyard authorsplacing pool, waterfront, trees, and plants in the open spaces providing airflow and sunlight in the living space a bs tr ac ti on a pp ea ra nc e using abstract forms of natural elements in the motifs and decorations fig. 11. abstract patterns of nature in borojerdiha’s house in kashan (makinejad, 2008) 57 journal of sustainable architecture and civil engineering 2022/1/30 quality of semantic depth in housing. the scale of the questionnaire is based on the 5-point likert scale that to present the regression equation related to the effects of independent variables on semantic depth, the data have been fuzzy based on the following table and formula. to aggregate the occupants’ views, the average of the fuzzy numbers is obtained from the following equation. fuzzy number =(l, m, u) f.ave= ( ∑𝑙𝑙𝑙𝑙 𝑛𝑛𝑛𝑛 + ∑𝑚𝑚𝑚𝑚 𝑛𝑛𝑛𝑛 + ∑𝑢𝑢𝑢𝑢 𝑛𝑛𝑛𝑛 ) = (l, m, u) number of fuzzy numbers =n 𝑥𝑥𝑥𝑥 = 𝐿𝐿𝐿𝐿 + 𝑀𝑀𝑀𝑀 + 𝑈𝑈𝑈𝑈 3 (l, m, u) = fuzzy number n = number of fuzzy numbers after calculating the average of fuzzy numbers, the following equation is used to de-fuzzy. fuzzy number =(l, m, u) f.ave= ( ∑𝑙𝑙𝑙𝑙 𝑛𝑛𝑛𝑛 + ∑𝑚𝑚𝑚𝑚 𝑛𝑛𝑛𝑛 + ∑𝑢𝑢𝑢𝑢 𝑛𝑛𝑛𝑛 ) = (l, m, u) number of fuzzy numbers =n 𝑥𝑥𝑥𝑥 = 𝐿𝐿𝐿𝐿 + 𝑀𝑀𝑀𝑀 + 𝑈𝑈𝑈𝑈 3 the process of collecting data was in the spring of 2021 and the statistical sample includes 96 occupants of phase 1 of ekbatan residential town. to determine the importance of the effectiveness of each of the semantic components of aan in improving the quality of semantic depth, regression analysis was performed on the obtained results of the questionnaire. field study fig. 12 location of the ekbatan residential town. source: (yasemi, 2016) a field study has been conducted in the southern part of phase one of ekbatan residential town located in the west of tehran (district 5). the initial design of this town is related to the period when the functionalism of modern architecture dominated the housing construction projects in iran, but landscape design, relationship with natural elements in the open spaces, and the presence of indicators related to this research’s variables in the design of this complex have been the reasons of its selection for the basis of the field study. the initial purpose of building ekbatan was to settle the surplus population of tehran. the construction of ekbatan was started in 1975 and at this time in 2021, this town consists of three phases including 33 blocks and 15675 residential units. the results of recognizing the indicators related to the research variables in the southern part of the first phase of ekbatan residential town are shown in table 3. table 2 the equivalent of triangular fuzzy numbers to the 5-point likert spectrum. source: (habibi, izadyar, & sarafrazi, 2014) (0,0,0/25)(0,0/25,0/50)(0/25,0/50,0/75)(0/50,0/75,1/00)(0/75,1/00,1/00) very lowlowmoderatehighvery high journal of sustainable architecture and civil engineering 2022/1/30 58 table 3 recognizing the semantic components of the aan in the ekbatan residential town. source: authors co m po ne nt s indicators descriptions figures u ni ty using module due to the nature of mass housing, the dimensions of volumetric composition components have been designated modularly. fig. 13. volumetric unity in ekbatan residential town. source: (yasemi, 2016) holistic approach (harmony with urban fabric in terms of orientation, building materials, full and empty spaces, and so on ) according to the modular design of the blocks, similar details in architectural forms, and using single material in the facades, the project is being seen as a coherent complex. using logical, numerical and geometric proportions the components of the volumetric composition have geometrically fixed proportions. fig. 14. fixed proportions in volumetric composition components. source: authors similar proportions in decorations and geometric structure no items were observed. tr an sp ar en cy mass reduction due to the dominance of space over mass (embedding the central courtyard and so on) the design of the volumetric module has been based on reducing the mass and increasing the negative spaces. fig. 15. reducing mass and increasing negative spaces in volumetric composition. source: authors visual continuity due to the sequence of spaces and the permeability of the walls the combination of positive and negative spaces and the diverse geometry of the plan reduce the rigidity of the form to some extent, however, the form is not visually permeable. use of reflection phenomena and translucent openings the horizontal stretched windows create less transparency compared with full-length windows. regarding the use of the reflection phenomenon due to the installation of ponds and fountains, etc., no significant case was observed. 59 journal of sustainable architecture and civil engineering 2022/1/30 co m po ne nt s indicators descriptions figures h on es ty compatibility of the facade and its backspaces the design of the facades does not represent the residential space and has mainly had a formal approach. fig. 16. view from different sides of the blocks. source: authors using functional components in the building the design of the volumetric composition and its related elements and details is quite functional. demonstrating the transfer of forces in the structure of building properly and the use of self-static forms and materials the forms are cubic and visually stable. using primary color and texture of natural materials the facade of the project is made from concrete with the primary color of cement. h ie ra rc hy functional and visual separation of different areas outside and inside the house at the scale of phase 1, the hierarchy of public, semi-public, semi-private (block lobby and floor lobby), and private (residential unit) spaces were observed. also, the separation of public, private, and service spaces at the level of residential units is evident. fig. 17. separation of public and semi-public spaces at the town level. source: authors customary separation of areas on the way to the house the negative spaces in the volumetric composition act as a semi-public space in the pedestrian access hierarchy of blocks. avoiding indoor visibility from outside the entrance of most residential units has a functional and visual filter space. fig. 18. separation of different areas at the level of residential units. source: authors journal of sustainable architecture and civil engineering 2022/1/30 60 co m po ne nt s indicators descriptions figures p ri m ar y ap pe ar an ce communicates with the sky, surrounding landscapes and natural elements on the upper floors, the northern units have a good view of the mountains of tehran. the central green space in each neighborhood unit has also provided the possibility of proper visual communication with the primary appearance of nature, from inside the residential unit. fig. 19. communication with the primary appearance of nature from inside the units and in the open spaces of the complex. source: authors placing pool, waterfront, trees, and plants in the open spaces the form of the blocks is designed in such a way as to create open spaces that can act as semi-public shared spaces. the greenery of these spaces has increased over time. fig. 20. greenery of negative spaces in volumetric composition. source: authors providing airflow and sunlight in the living space the blocks are stretched from west to east. the volumetric composition is such that the shading of the blocks on each other is reduced and most residential units can benefit from the desired airflow. fig. 21. formation of volumetric composition with the approach of maximum use of airflow and sunlight. source: authors a bs tr ac tio n a pp ea ra nc e using abstract forms of natural elements in the motifs and decorations no case was observed in the architecture of the whole project. this indicator is mostly seen in connection with the decorations and interior furniture of the units, which did not exist in the original design. fig. 22. association of natural patterns in the geometry of the plan. source: authors using abstract forms of natural elements in the forms of building components the plan of the blocks in phase one is reminiscent of the repetition of hexagonal patterns in nature. 61 journal of sustainable architecture and civil engineering 2022/1/30 results fig. 23 percentage of perceived quality of variables. source: authors the results of recognition of the variables' indicators and other technical documents of the ekbatan town were added to the questionnaire. in addition to the request for determining the perceived quality of the mentioned indicators, a request for determining the quality of semantic depth has also been submitted separately. based on the study of theoretical foundations and review of literature, it was found that architectural application of the four components of unity, transparency, honesty, and hierarchy, along with the presence of primary and abstract appearance of nature improves the quality of semantic depth in housing design. in statistical analysis, the quality of semantic depth is considered as a dependent variable on the 6 mentioned variables (semantic components of the aan). the descriptive results related to the percentage of perceived quality of independent and dependent variables are presented in figure 23. the results of the correlation test between the semantic depth variable and the semantic components of the aan show significant relationships. there was also no collinearity between the independent variables. these correlation coefficients confirm the establishment of the first condition for regression analysis. regression analysis coefficients are presented in table 5. these coefficients indicate that the components of the hierarchy and transparency have the greatest role in predicting changes of the semantic depth variable. table 4 pearson correlation coefficients between independent variables and semantic depth. source: authors honesty primary appearance hierarchy abstraction appearance transparency unity semantic depth pearson correlation .378** .387** .538** .359** . 407** .388** sig. (2-tailed) .000 .000 .000 .000 .000 .000 n 96 96 96 96 96 96 table 5 regression analysis coefficients. source: authors model unstandardized coefficients standardized coefficients t sig. collinearity statistics b std. error beta tolerance vif (constant) -0.168 .059 -2.840 .006 honesty 0.162 .074 .157 2.182 .032 .895 1.117 primary appearance 0.210 .080 .187 2.621 .010 .908 1.101 hierarchy 0.403 .072 .402 5.615 .000 .901 1.110 abstraction appearance 0.124 .060 .147 2.058 .043 .906 1.104 transparency 0.313 .077 .287 4.065 .000 .925 1.081 unity 0.148 .057 .186 2.610 .011 .912 1.097 a. dependent variable: semantic depth primary appearance honesty hierarchy abstraction appearance transparency unity semantic depth journal of sustainable architecture and civil engineering 2022/1/30 62 discussion and conclusion one of the main factors in making a difference in the concept of the house with shelter is the quality of semantic depth in housing design. housing is not a purely functional subject, and in a meaningless home, it is not possible to respond to the higher residential needs of human beings, so the presence of semantic layers in residential environments is necessary to provide a platform for growth and excellence of human personality. understanding the semantic layers of residential environments is deeply dependent on the cultural context of the target community and the individual’s mental readiness to face the signs and symptoms that convey concepts. due to the position of nature in the iranian-islamic culture, qualitative improvement of components of the aan is one of the main factors of improving the quality of semantic depth in housing design. the important point is the quality of applying these components and providing a context in which the person can be able to mentally concentrate and understand the concepts of components of the aan. the results of the present study confirm that observing the principle of spatial hierarchy which separation of areas, installation of filter spaces, and control of visual communication between areas are its architectural indicators alongside applying the transparency component are key factors in improving the quality of semantic depth in iranian urban housing design. this relationship can be interpreted from this perspective that observance of the principle of the spatial hierarchy provides the necessary basis for the mental preparation of residents to understand the semantic layers resulting from the presence of other semantic components of the architectural application of nature. transparency is also the most important factor in creating a visual connection between residents and aspects of nature from the interior spaces. therefore, it is another key component in improving the quality of semantic depth in housing architecture. based on the importance of each component of the aan in improving the quality of semantic depth in housing design, the following strategies and tactics are proposed in the design of contemporary urban housing. table 6 proposed strategies and tactics to enhance the semantic depth quality in housing design based on the importance of semantic components of the aan (source: authors) semantic components of the aan strategies tactics h ie ra rc hy observing the spatial hierarchy concerning access from public spaces to private spaces designing neighborhood units and semi-public and semi-private spaces at the neighborhood level observing the visual privacy of indoor spaces in apartment complexes functional and visual separation of the areas at the residential unit level avoiding the placement of the openings of residential units in front of each other blocking the direct sight of the entrance to other indoor spaces by using hashti. considering the proper depth for terraces observing the visual privacy of the courtyards and interiors in single-family houses avoiding the access of strangers to the courtyard by applying height restrictions on the residential urban fabric and arranging for openings providing visual privacy by planting avoiding direct sight from the entrance to the yard functional and visual separation at home level tr an sp ar en cy the dominance of space over mass creating porosity in architectural volumes continuity of visual corridors visual communication between interior and exterior spaces by using appropriate openings visual continuity in the separation of interior spaces 63 journal of sustainable architecture and civil engineering 2022/1/30 semantic components of the aan strategies tactics p ri m ar y ap pe ar an ce avoiding blocking visual corridors to natural elements suitable designing of the residential urban fabric to maintain the visual communication of the house with the sky and other natural elements planting trees and plants in the yard and making it possible to communicate with them using suitable openings to maintain the visual communication of the main spaces with the plants and trees in the courtyard of single-family houses h on es ty observing the principle of honesty in designing form and details avoiding the use of vain elements without a structural or functional role in the building coordinating building facades, dimensions of openings, materials, etc. with interior spaces avoiding unnecessary decoration u ni ty creating harmony in the residential urban fabric in terms of form, the orientation of buildings, density and occupancy area developing appropriate regulations regarding compliance with occupancy and density observing the geometrical proportions between different elements residential units separation and building design based on appropriate base modules observing the geometrical proportions between different elements residential units separation and building design based on appropriate base modules a bs tr ac ti on ap pe ar an ce the application of abstract appearance of nature designing patterns based on the abstraction of nature references adeli, s. nature and architecture in islamic 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(g. memarian, ed.) tehran: iust; 1992. pirnia, m. stylistics of iranian architecture. (g. memarian, ed.) tehran: sorush danesh; 1997. rowe, c., & slutzky, r. transparency: literal and phenomenal. perspecta; 1963. https://doi.org/10.2307/1566901 shia, e. with the city and region in iran. tehran: iust; 2007. spirn, a. w. language of landscape (later printing edition ed.). new haven: yale university press; 2000. tabibian, m., charbgoo, n., & abdolahimehr, e. (2012). the principle of hierarchy reflection in islamic iranian cities. armanshahr architecture & urban development, 2012; 4(7), 63-76. vincent, j. biomimetics in architectural design. intelligent buildings international, 2014;12, 1-12. wilson, e.o. biophilia: the human bond with other species. ma: harvard university press, cambridge; 1984. wilson, e.o. biophilia and the conservation ethic. in: kellert, s.r., wilson, edward osborne (eds.), the biophilia hypothesis. island press; 1993. yasemi, m. ekbatan residential town. retrieved from memarima: http://www.memarima.ir/, 2016. zhong, w., schroder, t., & bekkering, j. biophilic design in architecture and its contributions to health, well-being, and sustainability: a critical review. frontiers of architectural research, (in press). about the authors mohammadhossein azizibabani ph.d. student in architecture department of architecture, faculty of arts, tarbiat modares university, tehran, iran main research area affordable housing design, sustainable design address faculty of arts, tarbiat modares university, tehran, iran tel. +989120929844 e-mail: m.azizibabani@modares.ac.ir mohammadreza bemanian professor at the department of architecture faculty of arts, tarbiat modares university, tehran, iran main research area iranian islamic architecture, architectural planning and management address faculty of arts, tarbiat modares university, tehran, iran tel. +98(21)82883711 e-mail: bemanian@modares.ac.ir this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 33 journal of sustainable architecture and civil engineering 2021/2/29 *corresponding author: ghadayounis@uomosul.edu.iq design strategies for healing internal environments and workplaces a theoretical framework received 2021/02/11 accepted after revision 2021/07/05 journal of sustainable architecture and civil engineering vol. 2 / no. 29 / 2021 pp. 33-48 doi 10.5755/j01.sace.29.2.28497 design strategies for healing internal environments and workplaces a theoretical framework jsace 2/29 http://dx.doi.org/10.5755/j01.sace.29.2.28497 ghada m. younis* the university of mosul, college of engineering, department of architecture, mosul, iraq introduction the purpose of this paper is to construct a theoretical framework for designing healing environments by drawing from existing research. the approach of the paper surveys the literature on how elements of the design have been brought to bear on healing. this effort leads to a holistic approach that considers multiple dimensions of healing as both an individual and social process. the findings of the paper are harnesses that knowledge to provide a theoretical framework based on three design strategies: 1) supporting strategies that use specific elements to reinforce physical health, vital life energy, and psychological well-being; 2) balancing strategies that are oriented toward harmonizing those elements; and 3) nourishing strategies that address emotions, spiritual life, and the soul. originality, in summary, this paper traces efforts to harmonize individual human health with the built environment across time and uses related knowledge to crystallize a new theoretical framework. it is hoped that this survey of the literature may add to holistic and systemic understandings of healing environments. keywords: healing environments, salutogenesis, biophilic architecture, anthroposophical healing, healthy city profiles. the concept of healing is based on the creation of natural features around human habitation, artificial healing, one of the most important proposals associated with a hospital environment that fits a person's lifestyle. the study focuses on building a framework for designing strategies for the treatment of the built environment, reviewing specific health architectural studies as a first step: identifying the natural health features or general health appearance of the built environment, and the second step: spiritual, building a typical model the modern industrial-era hospital is not only architecturally fragmented as a structure, reflecting the needs of bureaucracy, but it is also fragmented as a process, making it difficult for staff to truly cooperate. as a result, it is usually only the symptoms that receive treatment and not the underlying and more complex origin or cause of the illness. kimball, for example, (2005) described modern hospital structures as "paternalistic, fragmented, independent silos, top-down, top-heavy, bureaucratic, multiple layers, hierarchical, like a bureaucracy state, lack of two-way communication, physician-centric, model-driven clinical model. of business". this is a rather strong condemnation journal of sustainable architecture and civil engineering 2021/2/29 34 of the healthcare systems that prevails in much of the world, but unfortunately, it appears to be accurate. even empirical studies reinforce that conclusion. for example, badash (2017) found that " the current health care system in the united states (us) is characterized by high costs and adverse patient outcomes". the article aims to define the main design strategies of healing internal environments, as presented below, this paper identifies three basic sets of strategies for designing healing environments and workplaces. first, there are supporting strategies that use specific elements to reinforce physical health, vital life energy, and psychological well-being. a large body of research has emphasized the role played by natural light, color, surfaces, spaces, sounds, and other elements. alone or together, they are associated with positive health, and more specifically with health that is 1) physical, 2) part of the vital life energy; and 3) psychological. recognizing the importance of those elements and implementing them in the context of healing is what represents supporting strategies. second, there are balancing strategies that are oriented toward harmonizing those elements. the work of asmussen in particular calls attention to the importance of having elements combine, and building design comes together, in a manner that reinforces the various dimensions of human health. here, the central concept is the manifestation of opposing yet complementary forces, one that achieves a higher sense of unity, or one that moves from thesis and antithesis to a new thesis. as described in the earlier part of the paper, a sense of harmony, balance, and equilibrium is directly related to health and healing. a balance of design and its elements is therefore reflected in a balance of dynamic life experiences. balance is essential for spiritual well-being, as well as for the spiritual health of the soul. third, there are nourishing strategies that address emotions, spiritual life, and the soul. we may not be able to design the atmosphere of the area, but we can design air-conditioning facilities, which show how the area is used, acquired, and how much it is valued. this third strategy, in a sense, goes beyond the basics. it involves concepts and forces across all levels of the body, mind, spirit, and soul. here, too, asmussen contributed by developing an architecture that reinforced the life-sustaining factor of healing. architecture has the task of making people feel belong and at peace with their world. additionfig. 1 a theoretical framework of design strategies in support of health and healing first, there are supporting strategies that use specific elements to reinforce physical health, vital life energy, and psychological well-being. a large body of research has emphasized the role played by natural light, color, surfaces, spaces, sounds, and other elements. alone or together, they are associated with positive health, and more specifically with health that is 1) physical, 2) part of the vital life energy; and 3) psychological. recognizing the importance of those elements and implementing them in the context of healing is what represents supporting strategies. second, there are balancing strategies that are oriented toward harmonizing those elements. the work of asmussen in particular calls attention to the importance of having elements combine, and building design comes together, in a manner that reinforces the various dimensions of human health. here, the central concept is the manifestation of opposing yet complementary forces, one that achieves a higher sense of unity, or one that moves from thesis and antithesis to a new thesis. as described in the earlier part of the paper, a sense of harmony, balance, and equilibrium is directly related to health and healing. a balance of design and its elements is therefore reflected in a balance of dynamic life experiences. balance is essential for spiritual well-being, as well as for the spiritual health of the soul. third, there are nourishing strategies that address emotions, spiritual life, and the soul. we may not be able to design the atmosphere of the area, but we can design air-conditioning facilities, which show how the area is used, acquired, and how much it is valued. this third strategy, in a sense, goes beyond the basics. it involves concepts and forces across all levels of the body, mind, spirit, and soul. here, too, asmussen contributed by developing an architecture that reinforced the life-sustaining factor of healing. architecture has the task of making people feel belong and at peace with their world. additionally, this third strategy also speaks to the quality of emotional nourishment, and joy. a roadmap of the theoretical approach is provided in figure 1 below. figure 1: a theoretical framework of design strategies in support of health and healing the three strategies described above are not entirely new or invented; they are reformulations of existing approaches that account for how wide and deep the research field is, and that also account for the latest developments in the literature. before delving into the literature and extracting the most useful insights, it is important to define terms and concepts. definitions of healing are abundant but among the most compelling is that of jonas et al. (2003): "healing is a dynamic process of recovery, repair, restoration, and transformation of the mind, body, and soul on the path to becoming more whole. healing occurs at many levels of the human system— mental, physical, emotional and spiritual". the definition of health above also recognizes that the true nature of illness and disease is more systemic than suggested by mainstream medicine. the process of healing, as explained by day (2003) should be understood in the context surrounding the individual, family, and society. when a person’s ally, this third strategy also speaks to the quality of emotional nourishment, and joy. a roadmap of the theoretical approach is provided in fig. 1. the three strategies described above are not entirely new or invented; they are reformulations of existing approaches that account for how wide and deep the research field is, and that also account for the latest developments in the literature. before delving into the literature and extracting the most useful insights, it is important to define terms and concepts. definitions of healing are abundant but among the most compelling is that of jonas et al. (2003): "healing is a dynamic process of recovery, repair, restoration, and transformation of the mind, body, and soul on the path to becoming more whole. healing occurs at many levels of the human system—mental, physical, emotional and spiritual". the definition of health above also recognizes that the true nature of illness and disease is more systemic than suggested by mainstream medicine. the process of healing, as explained by day (2003) should be understood in the context surrounding the individual, family, and society. when a person’s systems – mental, physical, emotional, and spiritual – are thrown off balance and into 35 journal of sustainable architecture and civil engineering 2021/2/29 a state of disequilibrium, there are often symptoms that manifest as physical problems. so, what is often regarded as a disease is in reality the outward manifestation of a more underlying or systemic problem. fortunately, the human body still retains its inherent and instinctual capacity to return to a state of internal stability, to a normal state of homeostasis and full balance. healing and healthcare, therefore, are partly about reconnecting the individual patient with this inherent capacity. day (2003) also added that the healing process involves an individual integrating the different levels of physical, emotional, and spiritual life, including the soul. the perspective described above is compatible with an approach known as anthroposophical medicine, which also approaches human health from a systemic or holistic perspective. more specifically, the anthroposophical concept, conceives of the human organism as a manifestation of multiple elements including physical forces, formative growth forces, and an interacting anima, or soul, as outlined by (sparby, 2020) (kienle et al. 2019). from this perspective, human existence can be thought of as a kind of system of systems, complete with sensory, motor, nervous, and circulatory systems, and, finally, with an additional geist, or spirit, involved in individual expression and reflection. it is important to note that scholars are not the only ones crystallizing definitions of health. the world health organization (who), as an international organization affiliated with the united nations, described health in its constitution in holistic terms: “health is a state of complete physical, mental and social well-being, not just the absence of illness” (who, 1948). the literature has also a section included efforts to move towards a holistic definition of a healing environment. in this effort, jonas define a healing environment as follows:, (jonas et al. 2003) “an an ideal environment for healing the system and environment that contains people, morals, treatments, and their psychological and physical boundaries. its purpose is to provide conditions that promote and support the healing power of participants, their relationships, and their environment. this area may include general and specific physical, behavioral, psychological, social and spiritual components including treatment". one attractive aspect of this definition is that it builds upon a holistic conceptualization of health to merge structure and process, that is, combining the ideas of a healthy built environment with professional practices, allowing healthcare providers to actualize their natural and professional talents. the next section consists of an extended literature review that is divided into three parts, each corresponding with a different set of design strategies: supporting, balancing, and nourishing. the research methodology is in building a comprehensive conception of studies related to the description, interpretation, and evaluation of healing environments as a theoretical base that is a guide that supports designers of health buildings. main strategies of healing design (literature review) this document emphasizes design approaches that address design elements that promote and enhance self-healing capacity to create interiors that define a healthy lifestyle and are especially important for sick or safe people. three basic techniques are considered here as flow: supporting strategies there is a large and growing body of research on the elements that are most critical to supporting healing and healing environments. regarding specific elements, zetterquist (2009) pointed out that color can nourishes people not just in terms of their senses but also emotionally. from this perspective, color is not only an aesthetic property but can exert a subtle emotional or psychological effect and create a different mood. vienneau (2019), too, recently focused on the element of color, noting that there has been a shift and that healthcare settings, colors "… such as gold curries, kiwi vegetables, crimson, and caribbean blues are now considered as stimulant healing tools and therefore can directly promote healing ".water, in addition to color, plays a role in healing environments as a symbol of peace, tranquility, and life. water can be associated with energy, movement, and journal of sustainable architecture and civil engineering 2021/2/29 36 abundance, which contribute to a sense of belonging. this natural phenomenon is often found in hospital gardens, which are often associated with the power of cosmic art (stark, 2000). empirical findings support the observations above. the study of multiple sclerosis patients by zetterquist (2009), for example, found that sunlight, color, and surfaces all exerted beneficial psychological influences. in addition, stichler (2001) persuasively he argued that "natural views, natural light, soothing colors, therapeutic sounds, and human family interactions can improve the healing process". another important factor is odor, especially the relationship between smell and health, and this access is the basis of aromatherapy. in this approach, rooms with a pleasant aroma of nature, flowers, and greenery, thus evoking a sense of vitality (day, 2003). numerous scholars have been inspired to illustrate or test, with empirical research, the issues and questions arising in the field. here, it is important to note the work of mirkine (1996) and specifically the paper “physical, spiritual, emotional, and psychological features in motivational buildings healing.” this research refers to the architectural building environment having the capacity to either strengthen or weaken the human immune system. some of the factors involved are physical, such as a sufficient oxygen level or the presence of toxic chemical compounds, while other factors are sensory and include a comfortable temperature and a sense of open space and personal mobility, which has a psychological influence on the immune system as well. some hospitals calculate these physical and sensory factors when evaluating policies and practices (mirkine,1996). indeed, what is important to recognize in this field is that there is a mutually reinforcing relationship between theory and empirical research. thus far, most of the literature surveyed has concerned itself with healing and the healing environment as they relate to hospitals, nursing homes, and other healthcare settings. scholars have also recognized the importance of these principles in other settings, and in fact, numerous institutions and companies have translated those principles into practice. here, it is important to note the development of a closely related research field, that of ergonomics, which has as one goal the shaping of the workplace environment so that it accommodates human factors. the research exploring this field includes boff's (2006) "revolutions and shifting paradigms in human factors and ergonomics," and gainer's (2008) "history of ergonomics and occupational therapy," and rucker's (2016) "the interesting history of workplace wellness." within the context of healing environments but still related to ergonomics, gray and birrell (2014) conducted a study that found that human-centric, biophilic designs for the workplace can "it improves productivity, improves pressure, improves well-being, promotes a co-operative work environment and promotes job satisfaction, thereby contributing to a higher workplace." in a similar vein, wallmann-sperlich et al. (2019) explained that biophilic methods bring a natural environment to the workplace, and “preliminary data show positive effects on reducing stress and high productivity in the workplace”. more recently, biophilic architecture, which includes green and intelligent buildings, mitigates negative influences on health from indoor work and exerts a positive influence, reinforcing physiological prosperity and psychological health:( asim and shree, 2019) "in terms of efficiency, popularity, and productivity indoors, it is seen as a catalyst for constructive thinking and improving creativity…, which can improve mental performance, reduce stress, and provide peace of mind within the built environment.". some of the principles described above have been extended to other employment settings. vienneau (2019), for example, considered correctional environments such as prisons, and observed the following: “noise pollution noise (i.e., "unwanted noise") is a common problem in correctional facilities due to overcrowding, sliding doors, loud speakers, working equipment, and televisions. it is widely known that excessive noise can cause communication problems, but can also affect physical well-being ”. 37 journal of sustainable architecture and civil engineering 2021/2/29 in this research field, a critical tipping point seems to be the realization that virtually every design principle mentioned above in the context of healthcare may also be applied to society at large. for example, make the case convincingly: we also suggest that through the use of biophilic design traditional planning for traditional preservation will be improved as it will incorporate human physical, social and psychological well-being. the purpose of biophilic design is to integrate social and environmental sciences to produce human settlements that support human ecosystems.…”( baldwin, powell, and kellert (2011). why do researchers even go down this road of inquiry? what motivates extending these concepts and principles to the urban infrastructure? one justification is because society as a whole suffers from the illness, that is, the average person suffers from the "discontents" of "civilization" as sigmund freud might say – especially when one considers that life expectancy rates are declining in much of the developed world. ho and hendi (2018), for instance, found that life expectancy was falling in high-income countries, reversing a historic trend: "most of the countries most leading in the study experienced a decline in life expectancy between 2014-15; of 18 countries, 12 face a decline in the life expectancy of women and 11 experience a decrease in the life expectancy of men". regarding falling life-expectancy rates, the most recent studies highlight the negative health influence of obesity, a cause of type-2 diabetes, heart disease, and a myriad of other health problems. suicide and the opioid addiction crisis in the united states also contribute to the reversal of life expectancy rates such that they are now decreasing in many countries. berdine (2019) observed that in the us, the center for disease control has reported falling life-expectancy rates for three years in a row and that it is not caused by elderly people dying sooner but rather by more young people dying sooner: " the increase in mortality rates among young people is due to general suicide and opioid overdoses in particular". in mainstream society, few people imagine that a building's architecture can have such a profound effect on human health, but decades of research suggest that this is the case. lundin (2015), for example, believes that architecture, despite being a non-medical medium, can indirectly support the recovery process by offering "functional possibilities" and "supportive space" for therapeutic experiences (lundin, 2015). in some ways, modern society had to come to this realization the hard way by discovering an association between certain buildings and their materials and sickness. lee and van orden (2008), for example, noted how in the 1970s scientists linked lung diseases to asbestos, a fire-retardant commonly sprayed on interior walls in the united states. this situation led to political controversy, multiple lawsuits, and many cases of lung disease. as inspectors turned their attention to industrial buildings and workplaces, they discovered a myriad of other materials that made people sick, along with related problems of ventilation (marinelli and bierman, 1995) and chemical irritation of the eyes, nose, and throat, skin, and nerves (goodish, 1995). many of these problems raised awareness about the importance of the built environment in human health. in hindsight, western societies had shown concerns over unhealthy urban conditions in previous centuries. back in the early 19th-century, the built environment could be described as unhealthy, even sick. davies (2015), for example, conducted an in-depth historical study and found that sickness and death in that era were due to a confluence of eight problems related to the built environment, and these are listed below. 1. overcrowding. this increased exposure to infectious communicable diseases. 2. a lack of freshwater, plumbing, and sewage treatment. at that time, it was common for the fecal material of both humans and horses to contaminate the water supply. 3. a lack of personal hygiene in the general population. these unsanitary conditions allowed the disease to proliferate. journal of sustainable architecture and civil engineering 2021/2/29 38 4. a lack of building regulations and housing codes. this deficiency led to many buildings with overcrowding, a lack of ventilation, and an absence of sunlight, increasing the risk of respiratory disease. 5. pollution. this toxic discharge resulted from industrial plants and a reliance on coal to heat homes. 6. dangerous working conditions in mines and factories. 7. population density. this entails the concentration of poor people in certain parts of the city. 8. inadequate medical infrastructure. this speaks to the population’s limited degree of medical knowledge and irregular access to medical care (481). a breakthrough of sorts was made in the mid-19th century with john snow’s map of the cholera outbreak in london. this was one of the first scientific milestones in linking the built environment and its configuration to disease. as described by sarkar and webster (2017), in 1851 john snow used point mapping to trace the origin of the cholera outbreak to one single contaminated source of water. sarkar and webster (2017) were understandably impressed by the progress made since then: "for the first time in human history, we are now in a position to track down health organizations for the best diversity in urban planning. in a few months at the time of writing, the uk will have fig. 2 john snow’s 1851 map of the cholera outbreak in london 1. overcrowding. this increased exposure to infectious communicable diseases. 2. a lack of freshwater, plumbing, and sewage treatment. at that time, it was common for the fecal material of both humans and horses to contaminate the water supply. 3. a lack of personal hygiene in the general population. these unsanitary conditions allowed the disease to proliferate. 4. a lack of building regulations and housing codes. this deficiency led to many buildings with overcrowding, a lack of ventilation, and an absence of sunlight, increasing the risk of respiratory disease. 5. pollution. this toxic discharge resulted from industrial plants and a reliance on coal to heat homes. 6. dangerous working conditions in mines and factories. 7. population density. this entails the concentration of poor people in certain parts of the city. 8. inadequate medical infrastructure. this speaks to the population’s limited degree of medical knowledge and irregular access to medical care (481). a breakthrough of sorts was made in the mid-19th century with john snow’s map of the cholera outbreak in london. this was one of the first scientific milestones in linking the built environment and its configuration to disease. as described by sarkar and webster (2017), in 1851 john snow used point mapping to trace the origin of the cholera outbreak to one single contaminated source of water. sarkar and webster (2017) were understandably impressed by the progress made since then: "for the first time in human history, we are now in a position to track down health organizations for the best diversity in urban planning. in a few months at the time of writing, the uk will have unparalleled national data infrastructure and evidence-based evidence for the relationship between city planning and planning and specific health outcomes" (figure 2). figure 2: john snow’s 1851 map of the cholera outbreak in london source: harvard university, the prediction project (2020) thus, as demonstrated by sarkar and webster (2017), the study of healthy and unhealthy built environments has moved beyond depending on a few lone individuals or institutions, who in turn rely on sparse sets of data. the 1980s was a turning point with the introduction of geographic information systems (gis). today, such analysis can also incorporate big data, data linkage, crowdsourcing, crowd computing, and artificial intelligence (ai). the time appears to be right for the extension of healing environments to the wider urban setting (capolongo, 2018). guan, roös, and jones, d. s. (2018) echoed the importance of these principles. fortunately, a theory has been put into practice in various cities around the world – in parts of those cities, as a start – including singapore, hong kong, and elsewhere. tan et al. (2019), for example, unparalleled national data infrastructure and evidence-based evidence for the relationship between city planning and planning and specific health outcomes" (fig. 2). thus, as demonstrated by sarkar and webster (2017), the study of healthy and unhealthy built environments has moved beyond depending on a few lone individuals or institutions, who in turn rely on sparse sets of data. the 1980s was a turning point with the introduction of geographic information systems (gis). today, such analysis can also incorporate big data, data linkage, crowdsourcing, crowd computing, and artificial intelligence (ai). the time appears to be right for the extension of healing environments to the wider urban setting (capolongo, 2018). guan, roös, and jones, d. s. (2018) echoed the importance of these principles. fortunately, a theory has been put into practice in various cities around the world – in parts of those cities, as a start – including singapore, hong kong, and elsewhere. tan et al. (2019), for example, conducted a study of 326 older people in hong kong and tainan (taiwan region), which was designed to understand how adults view the urban green spaces (ugss), and found that positive relationships have been found between the health facility and the perceived safety in ugs. relationships were stronger for older adults living alone ”. in this effort to apply healing principles and practices to the wider built environment, or to assess and evaluate those programs that have already been implemented, one useful tool that may be used in this extension, in this expansion, is the biophilic healing index. this index can be used to predict and measure the effects of the built environment on well-being. salingaros (2020) is among the researchers most active in this area and describes the field as follows: “the proposed "biophilic healing index" a number from 0 to 20 allows us to quickly examine those aspects of human health that have been improved due to environmental geometry. biophilia refers to human reactions to living organisms and to the very special 'biophilic' geometry of our environment". source: harvard university, the prediction project (2020) 39 journal of sustainable architecture and civil engineering 2021/2/29 salingaros (2020) also explained that the positive effects of biophilia are produced "1) in close proximity and visible interactions with plants, animals, and other humans; and 2) positive feedback on artificial insemination following geometric rules…" (13). seriously, these statements are now being investigated because people in such biophilic structures produce areas of emotional response "that can be measured by medical senses such as heart rate, skin temperature, and behavior, adrenaline level, student size, etc.". given the benefits outlined above, beatley and newman (2013) contributed arguments to the discussion by extending the concept of health to human security in a larger sense: "biophilic cities are cities that provide close and daily contact with nature, the surrounding environment, but also seek to promote awareness and care of this species. biophilic cities, it is said here, are also sustainable and strong cities. achieving the conditions of a living city will go a long way in promoting social and environmental resilience, in the face of climate change, natural disasters and economic uncertainty and the various fears that cities will face in the future.". the context above is one in which physical and physiological factors are interrelated, making it is possible to conceive of the biophilic healing index and its measure of the degree to which something is biophilic. in the list below, each item on the index is assigned a numerical value of 0 (none), 1 (some), or 2 (a large amount), yielding a total whose maximum is 20. there are 10 components in the biophilic index as listed by salingaros (2020). 1. sunlight: the best from many indicators. 2. color: variety and combination of hues. 3. gravity: balance and balance about a straight axis. 4. fractals: things that happen on a depleted scale. 5. curves: on small, medium and large scales. 6. details: meant to attract the eye. 7. water: sound and visibility. 8. health: living plants, animals, and other people. 9. representation of nature: natural decoration, realistic paintings, sculptures and symbolic sculptures. 10. organized-complexity: intricate yet coherent designs. salingaros (2020) has also presented this index as a kind of equation as follows: biophilic index = light + color + gravity + fractals + curves + detail + water + life + representations-of-nature + organized-complexity. it is important to note that some cities have already had experience with metrics and evaluations of biophilic urban projects. xue et al. (2019) studied this issue in their paper, “from biophilic design to biophilic urbanism: stakeholders’ perspectives,” finding that in singapore the concepts of “biophilic infrastructure,” “sensorial design,” and “green space place-making” considered by stakeholders to be most cost-effective strategies” (195). numerous scholars have been working along parallel lines. liao (2019), for example, argued that it is time that cities be redesigned so that they reflect the principles discussed here: “deliberate efforts are needed to improve the ecosystem functions of green urban areas, including parks, streams and river streams, planting roads, etc., to turn it into a real infrastructure or what benedict and mcmahon (2002) are all a ‘life support system’, without any disruption to urban development". as suggested in the trajectory of this survey thus far, the principles of health, healing environments, and biophilic built environments have expanded across time to include non-healthcare settings and urban infrastructure. balancing strategies scholarship has effectively addressed many of the topics related to the concept of balancing strategies. zborowsky and kreitzer (2009), for example, whose work lends itself to hypothesis generation and testing, emphasized the importance of a three-dimensional relationship between journal of sustainable architecture and civil engineering 2021/2/29 40 people seeking a balance of body, mind, and soul, places based on wellness, and process as defined by efficiency and sustainability. such a model is illustrated below in fig. 3. a similar and related model – entirely consistent with those included above – is furnished by macallister, bellanti, and sakallaris (2016), who identified that a balance among elements is instrumental in a patient's healing experience, as illustrated in fig. 4 below. the concept of moderation also focused on the work of mahmood and tayib (2020), which found that there are three key elements to building a fig. 3 optimal healing environments it is important to note that some cities have already had experience with metrics and evaluations of biophilic urban projects. xue et al. (2019) studied this issue in their paper, “from biophilic design to biophilic urbanism: stakeholders’ perspectives,” finding that in singapore the concepts of “biophilic infrastructure,” “sensorial design,” and “green space place-making” considered by stakeholders to be most cost-effective strategies” (195). numerous scholars have been working along parallel lines. liao (2019), for example, argued that it is time that cities be redesigned so that they reflect the principles discussed here: “deliberate efforts are needed to improve the ecosystem functions of green urban areas, including parks, streams and river streams, planting roads, etc., to turn it into a real infrastructure or what benedict and mcmahon (2002) are all a ‘life support system’, without any disruption to urban development". as suggested in the trajectory of this survey thus far, the principles of health, healing environments, and biophilic built environments have expanded across time to include non-healthcare settings and urban infrastructure. 2.2 balancing strategies scholarship has effectively addressed many of the topics related to the concept of balancing strategies. zborowsky and kreitzer (2009), for example, whose work lends itself to hypothesis generation and testing, emphasized the importance of a three-dimensional relationship between people seeking a balance of body, mind, and soul, places based on wellness, and process as defined by efficiency and sustainability. such a model is illustrated below in figure 3. figure 3: optimal healing environments adapted from zborowsky and kreitzer (2009) a similar and related model – entirely consistent with those included above – is furnished by macallister, bellanti, and sakallaris (2016), who identified that a balance among elements is instrumental in a patient's healing experience, as illustrated in figure 4 below. the concept of moderation also focused on the work of mahmood and tayib (2020), which found that there are three key elements to building a healing environment: (1) appearance, (2) privacy, and (3) comfort and control. this is consistent with methods such as kienle et al. (2019), excluding anthroposophical medicine is also derived from both consensus-based and traditional and complementary medicine (t&cm) programs: "one important aspect of t&cm is to focus on patient-centered and multidisciplinary care as well as the integration of cultural perspectives on a variety of settings. it can contribute to the well-being and well-being of the people as part of the united nations sustainable development goals". this observation, among many others, moves towards a more holistic view of health and healing environments. the built environment surrounding the patient, along with the kinds of treatment given adapted from zborowsky and kreitzer (2009) healing environment: (1) appearance, (2) privacy, and (3) comfort and control. this is consistent with methods such as kienle et al. (2019), excluding anthroposophical medicine is also derived from both consensus-based and traditional and complementary medicine (t&cm) programs: "one important aspect of t&cm is to focus on patient-centered and multidisciplinary care as well as the integration of cultural perspectives on a variety of settings. it can contribute to the well-being and well-being of the people as part of the united nations sustainable development goals". this observation, among many others, moves towards a more holistic view of health and healing environments. the built environment surrounding the patient, along with the kinds of treatment given to the patient, is supremely important in this larger system of health. as will be shown, the combination of shapes, sounds, color, light, and other elements all affect a person in profound ways; they can create relief and bliss or, conversely, tension and stress. one of the tasks in this review is to identify the combinations of environmental elements which are most recognized by scholarship as exerting a positive influence on health and healing. in this research field, the work of ulrich (1984) is significant because it initiated a round of empirical analyses that lasted for decades. in that 1984 study, it was found that patients' recovery times were shorter for patients who had an immediate view of nature, of trees than it was for patients who faced a white wall (ulrich, 1984). this suggests that there is an equilibrium or balance between a patient's physical body and nature. later, many other studies would confirm and refine the finding that the human body benefits through direct exposure to natural environments. several years later, venolia (1988) argued that a healthy environment should accommodate the multiple levels of interaction between caregivers and patients. more specifically, venolia (1988) identified eight essential elements that should be brought together into a larger whole, most of which, in the decades to come, were further studied by scholars in the research area: 1. improve communication with nature, culture, and society. 2. enable the level of confidentiality required of the patient. 3. reduce physical damage. 4. space expansion with various incentives and various meanings. 5. encouraging and providing time for rest and peace. 6. allow people to interact with the environment. 7. balance and stability over flexibility. 8. the situation should be good. what is crucial to remember about these elements is that their presence in the built environment can manifest into a patient’s physical space as healing effects. in contrast, the absence or the opposites of these elements, when countering these eight basic principles, can manifest as detrimental influences on a patient’s health. 41 journal of sustainable architecture and civil engineering 2021/2/29 another interesting balancing strategy with non-western and chinese origins is that of feng shui. as described by mainenti (2018), this attention to the orientation and relationship between the built environment and cardinal directions is thought to play a factor in healing. also, as described by mak and ng (2008) in their paper, “feng shui: alternative framework for complexity in design, ”this traditional approach is ready to introduce the built environment:“ feng shui is a traditional chinese philosophy aimed at creating harmony between nature, buildings, and people ”. one well-known aspect of feng shui is the balance between the opposing yet complementary forces of yin and yang, with details about this knowledge contained in the yi jing or book of changes (unschuld, 1986). like contemporary systems theory and complexity theory, ancient chinese civilization also focused on the relationship between micro and macro, that is, between the individual and the larger environment. in this worldview, the individual is a part of the rhythms of astronomical, meteorological, climatic, and epidemiological cycles (needham, 2000). in addition to the concept of yin and yang, feng shui also has the five phases of north (water), east (wood), south (fire), west (metal), and center (earth), all of which factor into traditional chinese approaches to healing environments (mainenti, 2018). the basic concept of feng shui has been applied in western research. obiozo and smallwood (2017), for example, analyzed construction sites in terms of feng shui principles: "stress-related conditions from the construction environment that have no psychological and environmental implications lead to workers' injuries, and exclude their performance, as well as the cohesive integration of the workplace as a highly beneficial environment." and feng shui principles as a response to the psychological and constructive risks to construction through the expansion of construction sites ". granted, in the west, there is some disagreement over whether or not feng shui, as part of ancient chinese cosmology, is real science. this question might be answered more definitively one way or the other if and when a new scientific paradigm emerges, one with new technological tools with which to test related hypotheses. other scholars have developed ideas along similar lines, as have architects. consider, for example, erik asmussen's principles of life-enhancing designs, a topic addressed in the literature (coates, 2001). asmussen's architecture goes beyond matters of superficial appearance and reflects deeper functional and even spiritual elements. this involves the emergence of an architectural language merging artificial and organic forms, heightening one's sense of aliveness and participation in the outside world. asmussen's buildings are widely regarded as life-enhancing in that patients are empowered and can strengthen the vital life force. asmussen pointed out that architecture, in addition to efficiently provide for human needs, has the task of making people feel like ownership and beauty in the natural world. buildings that create a sense of harmony between artificial and nature and space, a higher sense of unity, can catalyze human self-healing and self-renewal of nature (coates, 2001). asmussen's architecture embodies seven vital principles of life-supporting design that are intended to support health and healing. these are listed below and then summarized in turn. it is important to remember that they are not intended to exist in isolation but rather in a unified balance(coates, 2001). 1. unity of form and function 2. unity 3. physical modification 4. it is in harmony with nature and space 5. living wall 6. color light and color vision 7. powerful balance of local experience first, there is the principle of unity of form and function, thus fusing the artificial and the natural in a way that enhances the mission or goal of the setting. second, there is polarity, or the inclusion journal of sustainable architecture and civil engineering 2021/2/29 42 of complementary opposites, including the rhythmic process of expansion and contraction: "to say those contrasting elements are polar is to say that they are at once different yet inseparably related" (coates, 2001). third, there is metamorphosis, meaning that things are not always what they appear and forms, surfaces, and colors can create new spaces and experiences at any moment. fourth, there is a sense of harmony with nature and the site such that the building feels like it belongs there. fifth, there is the concept of a living wall in that "downward-bearing load" and "upward-striving support" should be visible in the shape and surfaces of walls and windows, thus allowing the entire building to assume the qualities of a living and breathing organism (coates, 2001). sixth, there should be a sense of color luminosity and color perspective, and this is accomplished through the application of partially transparent layers of paint, thus creating a bright, luminescent surface that also has depth and richness. seventh, there is the principle of the dynamic equilibrium of spatial experience, which as explained by coates (2001) offers both security or intimacy and freedom: "consistency and flexibility, balancing and balancing, secure intimacy and increased openness are maintained in a critical and dynamic balance with the ever-changing experience of movement and relaxation. however whether one is moving or resting there is always a sense of dynamic balance where the seed of anti-space energy already contains the moment and the current. of equality and balance in all systems. nourishing strategies a closely related but distinct area of research includes that of strategies that nourish the spirit or soul. these strategies speak to a deeper level of influence by the elements concerned, and to a more profound sense of health and stability. for example, stark (2001) noted how certain "axes" factor into healing environments, and these include cosmic principles of life and earth energy, topography and guidance, healing gardens and water use, interior spaces and energy flow, and finally building's occupational practices or rituals. along similar lines, day (2003) conceived of healthy buildings as those that nourish life's vitality, its physical, mental, and spiritual vitality. fusing elements into a nourishing influence is an effort reflected in the work of dijkstra, pieterse, and pruyn (2006), for example, who examined the interplay of many factors: "best results have been obtained, especially for sunlight, windows, scents, and seating arrangements. inconsistent results have been obtained with sound, environment, landscape, television and several interventions." similarly, the benefits of providing sick children with “environmental exposure, play activities and testing spaces,” and found that they not only help children, give them the freedom to be a child again, not just a sick child, but also help student nurses gain “… broader understanding of health care without -biomedical. it changed their learning and opened their eyes to the holistic approach to caring for sick children ”(van der riet et al. 2017). nature is an element that has received considerable research attention. as observed by hand et al. (2017), nature supports children’s health: "children, in particular, are thought to show a deeper involvement in life (biophilia), and health disorders, such as attention deficit hyperactivity disorder, depression, obesity, and depression, are caused by a lack of contact with wildlife, which is called environmental disturbance.". olivos-jara (2020) also conducted an empirical study showing that for children, nature can have a positive psychological influence and reinforce their emotional intelligence. a study of how medical gardens can nourish and improve health care knowledge for patients with alzheimer’s and dementia. the authors found that gardens stimulated mental regeneration and had other positive physical, social, and psychological effects. as they conclude: "treatment gardens should be expanded to quickly locate more patients. future indicators for the construction of 43 journal of sustainable architecture and civil engineering 2021/2/29 health gardens with a focus on patient experience are directed" (uwajeh, polay, and iyendo, 2018) running parallel with research on nature, scholars have turned their attention to the nourishing potential of art and its creation, something that invariably involves color. arts-based activities have been found to promote healing. for example, abulawi, walker, and boyko (2019) conducted an empirical study whose participants included children from the ages of three to 18, parents, medical staff, and four teams of designers. art-based research activities and less formal discussions led to the conclusion that creating art can be part of the healing process. (abulawi, walker, and boyko, 2019). another factor or factor, which often gets little attention from research, is how history and cultural values can nourish emotional and spiritual health. jeong (2019), for example, has learned how the new seoul daehan hospital, which is part of the seoul national university medical center (snu) campus and hospital, is integrated with the historical site of kyungmo palace in a way that reflects traditional architectural styles. as described by jeong (2019): "snu medical campus and hospital is an excellent case study of the future of using cultural heritage sites as places of healing. the construction of a healing space for medical sites that use a historical and cultural site provides a new meaning to cultural heritage through its sustainable use". what is interesting about the jeong study is that while many scholars have focused on the role of nature, few have considered the potential of historical sites as healing environments. historical fig. 4 a framework for optimal healing environments and hospital, is integrated with the historical site of kyungmo palace in a way that reflects traditional architectural styles. as described by jeong (2019): "snu medical campus and hospital is an excellent case study of the future of using cultural heritage sites as places of healing. the construction of a healing space for medical sites that use a historical and cultural site provides a new meaning to cultural heritage through its sustainable use". what is interesting about the jeong study is that while many scholars have focused on the role of nature, few have considered the potential of historical sites as healing environments. historical sites may be of particular value for traditional and collectivist cultures, like those in asia. figure 4. figure 4: a framework for optimal healing environments source: adapted from macallister, bellanti, and sakallaris (2016) as demonstrated by decades of detailed scholarship, the potential nourishing effects of the surrounding environment, which includes many diverse elements, is a significant factor in healing. table s1 shows an overview of the theoretical framework of the study. 3. discussion and conclusion this paper engaged in a sustained review of the literature that confirms the value of three overlapping and mutually reinforcing strategies. academic research has engaged with the many elements of healing environments, along with systemic and holistic worldviews and perspectives. the exciting promise of this research field is one reason why the world now sees the extension of its elements and principles to settings beyond healthcare. at first, ergonomic, anthroposophical, and biophilic principles were extended to the workplace, to correctional facilities, and limited spaces or specific buildings. in time, these proposals could and should form the basis for a bold reformulation of life and healing. empirical testing has also shed light on just how significant these elements are. it is possible to consider the literature in its totality and propose a new theoretical framework consisting of three strategies. first, the paper has identified the importance of supporting strategies that use specific elements to reinforce physical health, vital life energy, and psychological well-being. this is an important preliminary step because it is necessary to identify specific elements. as shown in the paper, among the most important elements are light, shape, color, surfaces, and related ones such as nature and water. at this first stage, their combination, integration, or balancing is not the primary concern. in other words, supporting strategies tend to focus on the identification and distinguishing of specific elements and observations of how they support healing. second, the balancing elements take the theoretical construct to a higher level in that this level begins to situate and juxtapose the elements together. the goal of this effort is to reach a state of equilibrium between the elements such that it promotes the body's sense of equilibrium, in effect using the built sites may be of particular value for traditional and collectivist cultures, like those in asia. fig. 4. as demonstrated by decades of detailed scholarship, the potential nourishing effects of the surrounding environment, which includes many diverse elements, is a significant factor in healing. table s1 shows an overview of the theoretical framework of the study. this paper engaged in a sustained review of the literature that confirms the value of three overlapping and mutually reinforcing strategies. academic research has engaged with the many elements of healing environments, along with systemic and holistic worldviews and perspectives. the exciting promise of this research field is one reason why the world now sees the extension of its elements and principles to settings beyond healthcare. at first, ergonomic, anthroposophical, and biophilic principles were extended to the workplace, to correctional facilities, and limited spaces or specific buildings. in time, these proposals could and should form the basis for a bold reformulation of life and healing. empirical testing has also shed light on just how significant these elements are. it is possible to consider the literature in its totality and propose a new theoretical framework consisting of three strategies. first, the paper has identified the importance of supporting strategies that use specific elements to reinforce physical health, vital life energy, and psychological well-being. this is an important preliminary step because it is necessary to identify specific elements. as shown in the paper, among the most important elements are light, shape, color, surfaces, and related ones such as nature and water. at this first stage, their combination, integration, or balancing is not the primary concern. in other words, supporting strategies tend to focus on the identification and distinguishing of specific elements and observations of how they support healing. source: adapted from macallister, bellanti, and sakallaris (2016) discussion and conclusion journal of sustainable architecture and civil engineering 2021/2/29 44 table 1 shows an overview of the theoretical framework of the study basic vocabulary minor vocabulary possible values and physical characteristics d es ig n st ra te g ie s, e m pl oy m en t o f se lf -h ea lin g p ro ce ss s up po rt s tr at eg y physical support space character human scale reduce sharpness, the geometry of space space components character daylighting natural ventilation use of raw materials reduce environmental pollution of noise reduce electromagnetic pollution emf relationship of a space character personalization way-finding flexibility empowerment simulation coherence affordance control restoration vital support (life-energy) harmony with nature implantation at nature use of natural materials exposure of biological rhythm of nature (seasons, daily cycle) aspects of natural metaphors renewable breathing (contraction &expansion) growth fluidity & movement living wall interaction between enclosure& eligibility psychological support phenomenal impressions comfortable space pleasure space desirable space rewarding space prevent implicit passive feeling confusion of understanding difficulty the frustration of hard decision maker deny from neutral space lack of control disturbance of huge volume ugly of poor impressions sensitive responses cold, hard, bad, pollute, pure, warm, smooth…. ext change of character change of color change of smell change of light 45 journal of sustainable architecture and civil engineering 2021/2/29 basic vocabulary minor vocabulary possible values and physical characteristics d es ig n st ra te g ie s, e m pl oy m en t o f se lf -h ea lin g p ro ce ss b al an ce s tr at eg y the balance of life components balance of basic components lifestyle (body, soul, spirit) balance of dynamic life experience lifestyle (life energy) individual &group, participations &isolation, mental image & reality, static & dynamic space impression stability vs variation, order vs chaos, symmetry v's asymmetry, shelter v's openness, quite v's crowded balance of surroundings, environment components nature and quality of the environment (natural or manufacture) n ou ri sh m en t s tr at eg y soul nourishment-life factor nourishment genius loci (belonging to the natural world) renovation meaning derived from the cosmic renewal of nature orientation and the biological clock emotional nourishment brightness of daylight brightness of color nature elements (water, gardens, wild) second, the balancing elements take the theoretical construct to a higher level in that this level begins to situate and juxtapose the elements together. the goal of this effort is to reach a state of equilibrium between the elements such that it promotes the body's sense of equilibrium, in effect using the built environment to mirror and reinforce, physical health. from this perspective, balancing strategies are oriented toward integrating and transcending elements to reach a higher level of harmony. third, this paper has identified nourishing strategies for the spirit and soul. this level may incorporate or assimilate supporting and balancing strategies but the difference is that they speak to a higher level of spiritual consciousness and being. at first glance, the topic of healing environments seems narrow but this paper demonstrated that it is not. the topic is multi-dimensional and includes a wide spectrum of sub-0topics, some of them, such as feng shui, stretching back to antiquity. in large part, the latest developments may be seen as a reaction to the unhealthy state of cities and workplaces, a legacy of the industrial revolution. this paper calls for further research on the subjects raised above, including for more empirical studies on how healing principles may be evaluated once put into practice. 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(2009). healing environments: element of retreat, thesis in architecture. montana state university. ghada younis assistant professore department of architecture, college of engineering, university of mosul, mosul, iraq main research area architectural design address mosul, iraq. tel.+9647701786191 e-mail:ghadayounis@uomosul.edu.iq about the author this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 7 journal of sustainable architecture and civil engineering 2019/1/24 *corresponding author: targo.kalamees@taltech.ee energy performance, indoor air quality and comfort in new nearly zero energy day-care centres in northern climatic conditions received 2018/12/11 accepted after revision 2019/01/14 journal of sustainable architecture and civil engineering vol. 1 / no. 24 / 2019 pp. 7-16 doi 10.5755/j01.sace.24.1.22180 energy performance, indoor air quality and comfort in new nearly zero energy day-care centres in northern climatic conditions jsace 1/24 http://dx.doi.org/10.5755/j01.sace.24.1.22180 kalle kuusk tallinn university of technology, estonia ahmed kaiser aalto university, finland nicola lolli sintef, norway jan johansson växjö kommun, sweden tero hasu kouvola innovation ltd., finland anne gunnarshaug lien sintef, norway endrik arumägi, kristo kalbe, jaanus hallik tallinn university of technology, estonia jarek kurnitski aalto university, finland targo kalamees* tallinn university of technology, estonia the european energy policy pushes the member states to transform building stock into nearly zeroenergy buildings (nzeb). this paper is focused on data collected from existing nzeb day-care centres, in order to be able to assess possible differences between predicted and actual energy and indoor environmental performance. building structures, service systems and the indoor climate and energy performance of five day-care centres were investigated in estonia, finland and norway. indoor climate condition measurements showed that in general, the thermal environment and indoor air quality corresponded to the highest indoor climate categories i and ii (en 15251). building heating and ventilation systems in studied buildings are working without major problems. good indoor climate conditions journal of sustainable architecture and civil engineering 2019/1/24 8 were also reflected in the occupant satisfaction questionnaires. for most of the studied buildings, over 80% of the people marked all indoor environment condition parameters (thermal comfort, indoor air quality, acoustics, odour and illuminance) acceptable. the thermal environment in the cooling season was reported problematic because it was lower than the minimum temperature for indoor climate category ii. energy consumption analysis showed that measured real energy use was higher, or even significantly higher, than the energy use calculated during the design phase. potential causes of the higher actual energy consumption are caused by differences of measured and designed solutions, methodology of the energy calculations, and the differences in user behaviour. lessons learnt from previously constructed day-care centres can be utilised in the planning and design of new nzebs. keywords: indoor thermal conditions, indoor air quality, occupant satisfaction, energy consumption, nzeb, day-care centres. by the end of 2020 (2018) for buildings occupied and owned by public authorities), all new buildings should comply with the energy performance of buildings directive (epbd, 2010) obligations. many member states (ms) have already shifted minimum requirements to the cost optimal level. kurnitski et al., (2018)as the latter was needed for comparing with the national nzeb requirements. in this comparison, various technical solutions were selected so that the building complied with ec recommendations. then the technical solutions were adjusted to achieve the closest compliance with the national nzeb requirements in the four selected eu countries. the technical solutions showing the highest energy performance highlighted the strictest national nzeb requirements. energy performance with national nzeb solutions was benchmarked against the ec recommendation by using input data representing a standard use and applying the iso 52000-1:2017 primary energy factors (pef showed that the direct comparison of the building energy performance between the ec recommendation and the national nzeb primary energy values produced inconsistent results because of the variation of both the primary energy factors and the energy calculation input data in national regulations. this complicates free movement of goods and services and overall export between member states. more information is needed on what kind of building properties are required in different countries to guarantee fulfilment of nzeb requirements. fisk (2017) showed, by literature review, that ventilation rates in classrooms often fall far short of the minimum ventilation rates specified in standards. it is important to assure healthy and clean environments to children in day-care centres because wheezing and other breathing related issues in preschool children are common (grigg and ducharme, 2019) and more than half of all school children have some kind of allergic condition (asthma, eczema and seasonal allergic rhinitis) (haanpää et al., 2018). kolarik et al. (2016) showed a statistically significant inverse relationship between sick-leave and the ventilation air exchange rate in day-care centres. therefore, it is extremely important that energy savings do not bring about a deterioration of the indoor climate. it is quite common that the real measured building energy consumption is much higher than the predicted consumption during design (de wilde, 2014; desideri et al., 2012). this performance gap hinders the realisation of energy conservation targets. achieving nearly zero-energy buildings (nzeb) needs multi-attribute assessment (zavadskas et al., 2017), as in addition to nearly zero or a very low amount of energy required, this required energy should be provided to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby. to guarantee nearly zero or a very low amount of energy use, the building envelope and service systems should be very effective. heat loss of the building envelope depends on thermal transmittance u, w/(m2 ∙ k), linear thermal transmittance ψ, w/(m∙k), point thermal transmittance χ, w/k, and airtightness of the building envelope q50, m 3/(hm2). bikas and chastas (2014) showed that in all climatic zones, the reduction of the thermal transmittance leads to a significant reduction in the primary energy consumption by end use, and in the energy requirements for heating. for example, the thermal transmittance of the external walls for nzeb should be 5% of older buildings thermal introduction 9 journal of sustainable architecture and civil engineering 2019/1/24 transmittance in latvia, 10% in estonia and up to 50% in portugal (kalamees et al., 2016). ilomets et al., (2017) showed that that thermal bridges contribute more than 30% of the total transmission heat loss, depending on the wall insulation thickness. levinskyte et al., (2016) showed that when effective solutions for linear thermal bridges are used, the same energy efficiency of the building can be reached using less thermal insulating layers and windows and doors of a lower thermal behaviour, if a building with better energy characteristics is designed. the existing situation of airtightness of the building envelope is often not sufficient (banionis et al., 2013). better information about effective energy performance measures helps design and construct buildings with a smaller performance gap. in addition to operational energy use, embodied energy (kylili et al., 2016) is also important, as the latest epbd targets decarbonised building stock by 2050 (epbd, 2018). greater use of woodbased materials helps to reduce fossil energy use and to mitigate climate change. the primary energy used and the co2 emission resulting from production are lower for wood-framed constructions than for concrete-framed constructions (gustavsson and joelsson, 2010). this paper is focused on data collected from existing nzeb day-care centres, in order to be able to assess possible differences between predicted and actual energy and indoor environmental performance. the main objectives of current study are: _ to determine the technical solutions of modern, energy efficient, and nzeb day-care centres; _ to find out possible differences between predicted and actual energy and indoor environmental performance; _ to map the shortcomings that should be considered when designing future nzeb day-care centres. lessons learnt from previously constructed nzeb buildings can be utilised in the planning and design of new nzebs. methods studied buildings the energy use, indoor climate, and building envelope structures were investigated in five daycare centres in three countries, table 1, table 2, and fig. 1. most of the day-care centres were wooden buildings. table 1 basic information of studied day-care centres building description estonia 1 estonia 2 finland 1 finland 2 norway 1 construction year 2017 2017 2015 2014 2013 net floor area, m² 1539 1172 1170 1192 950 mean occupant density, 10 m²/person 12 m²/person 10 m²/person 10 m²/person 14.4 m²/person ventilation system supply-exhaust air handling units with heat recovery heating system / heat source floor and radiator heating /gas boiler floor and radiator heating / gshp floor and radiator heating/gas boiler floor heating / ground source heat pump (gshp) radiator heating / gshp cooling system / source none cooling coil in ventilation / gshp cooling coil in ventilation / air heat pump none cooling coil in ventilation / gshp on site renewable energy systems none pv-panels 17 kw none geothermal heat solar collectors 6m2 designed energy performance certificate (epc) c (minimum requirements) a (nzeb) c (minimum requirements) b (low energy building) ns 3700 (norwegian ph) heating degree days, tb 17 ºc 4220 4220 4392 4392 4302 vent. airflow rate 1.6 l/(m2 s) 2.5 l/(m2 s) 2.4 l/(m2 s) heat recovery efficiency 75 % 67 % 76 % 85 % specific fan power 2.0 kw/(m3/s) ≈2.0 kw/(m3/s) 1.85 kw/(m3/s) 1.9 kw/(m3/s) 1.3 kw/(m3/s) journal of sustainable architecture and civil engineering 2019/1/24 10 table 2 characteristics of building envelope estonia 1 estonia 2 finland 1 finland 2 norway 1 thermal transmittance u, w/(m² k) exterior walls 0.19 0.13 0.17 0.15 0.09 roof 0.10 0.06 0.09 0.08 0.09 ground floor 0.20 0.09 0.16 0.16 0.08 doors 1.00 1.10 1.00 1.00 0.80 windows 1.00 0.85 1.00 0.84 0.80 window g-value 0.25-0.50 <0.50 0.36 0.36 0.37 airtightness q50, m 3/(h∙m2) 3.8* 0.6 2.0 0.36 0.14 building structures timber frame concrete elements timber frame timber frame cross laminated timber * measured value estonia 1 estonia 2 finland 1 norway 1 finland 2 fig. 1 studied day-care centres evaluating energy consumption and indoor climate energy audits were done for each building to show the energy consumption. the information regarding energy consumption (electricity, space heating together with ventilation air heating (heat) and domestic hot water (dhw)) was measured and data was collected from building managers. heating energy consumption is normalised to the standard year climate conditions. to compare the gap between designed and measured energy consumption levels, we have used the following equation (equation 1): performance gap = 100 × (measured �m� – designed (d)) measured (m) % (1) indoor climate conditions were evaluated according to the standard en-15251 (2007). indoor environment quality is divided into four categories: i, ii, iii and iv, table 3. category i represents the highest level of expectation and is recommended for spaces occupied by sensitive persons such as the elderly and children. category ii represents normal conditions and should be used as the target for new and renovated buildings. category iii is the minimum an existing building should reach, while category iv represents ieq that should be acceptable for only a limited part of the year. table 3. indoor temperature range in different climate categories indoor climate parameter theating, ºc t<19 or t>25 22±3 22±2 22±1 tcooling, ºc t<22 or t>27 24.5±2.5 24.5±1.5 24.5±1 co2, ppm >1200 <1200 <900 <750 evaluating energy consumption and indoor climate energy audits were done for each building to show the energy consumption. the information regarding energy consumption (electricity, space heating together with ventilation air heating (heat) and domestic hot water (dhw)) was measured and data was collected from building managers. heating energy consumption is normalised to the standard year climate conditions. to compare the gap between designed and measured energy consumption levels, we have used the following equation (equation 1): estonia 1 estonia 2 finland 1 norway 1 finland 2 fig. 1 studied day-care centres evaluating energy consumption and indoor climate energy audits were done for each building to show the energy consumption. the information regarding energy consumption (electricity, space heating together with ventilation air heating (heat) and domestic hot water (dhw)) was measured and data was collected from building managers. heating energy consumption is normalised to the standard year climate conditions. to compare the gap between designed and measured energy consumption levels, we have used the following equation (equation 1): performance gap = 100 × (measured �m� – designed (d)) measured (m) % (1) indoor climate conditions were evaluated according to the standard en-15251 (2007). indoor environment quality is divided into four categories: i, ii, iii and iv, table 3. category i represents the highest level of expectation and is recommended for spaces occupied by sensitive persons such as the elderly and children. category ii represents normal conditions and should be used as the target for new and renovated buildings. category iii is the minimum an existing building should reach, while category iv represents ieq that should be acceptable for only a limited part of the year. table 3. indoor temperature range in different climate categories indoor climate parameter theating, ºc t<19 or t>25 22±3 22±2 22±1 tcooling, ºc t<22 or t>27 24.5±2.5 24.5±1.5 24.5±1 co2, ppm >1200 <1200 <900 <750 (1) indoor climate conditions were evaluated according to the standard en-15251 (2007). indoor environment quality is divided into four categories: i, ii, iii and iv, table 3. category i represents the estonia 1 estonia 2 finland 1 finland 2 norway 1 fig. 1 studied day-care centres 11 journal of sustainable architecture and civil engineering 2019/1/24 highest level of expectation and is recommended for spaces occupied by sensitive persons such as the elderly and children. category ii represents normal conditions and should be used as the target for new and renovated buildings. category iii is the minimum an existing building should reach, while category iv represents ieq that should be acceptable for only a limited part of the year. indoor climate conditions measurements (air temperature, rh, air velocity, co2) were conducted across the occupancy period from monday to friday during both heating (winter), and cooling (summer) seasons of occupancy. measurements were conducted in all buildings in at least 2–4 rooms during the heating and cooling periods. the temperature and humidity were measured with portable data loggers. airflow was measured using the supply and exhaust air airflows. indoor climate conditions were also assessed with occupant surveys delivered to employees. the survey included six questions regarding indoor environment quality including; thermal comfort, indoor air quality, acoustics, odour, and illuminance. thermal comfort, iaq, illuminance, and acoustics were assessed with a four-point scale from clearly acceptable to clearly unacceptable. odour was scaled with six possible answers from no odour to overpowering odour. thermal sensation was also surveyed with six possible answers from hot to cold. table 3 indoor temperature range in different climate categories indoor climate parameter iv iii ii i theating, ºc t<19 or t>25 22±3 22±2 22±1 tcooling, ºc t<22 or t>27 24.5±2.5 24.5±1.5 24.5±1 co2, ppm >1200 <1200 <900 <750 resultsmeasurements thermal comfort during the heating season, the room temperature corresponded to indoor climate category i or ii criteria 87% 100% of the time, fig. 2, fig. 3. during the cooling season correspondence to indoor climate category i or ii criteria was much smaller: 21% 54% of time in estonia, 15% 37% in finland, and in norway 100% of the time. thermal environment during the cooling season is in fig. 2 thermal comfort results in studied day-care centres during heating season fig. 3 thermal comfort results in studied day-care centres during cooling season day-care centre en 15251 classification: estonia 1 estonia 2 finland 1 finland 2 norway day-care centre en 15251 classification: estonia 1 estonia 2 finland 1 finland 2 norway fig. 3 journal of sustainable architecture and civil engineering 2019/1/24 12 indoor climate categories iii and iv because the measured room temperature was lower than the minimum temperature for indoor climate category ii. indoor air quality indoor air quality was evaluated based on indoor co2 concentration measurements during heating (fig. 4) and cooling (fig. 5) seasons. during the heating season, the indoor air quality corresponded to indoor climate category i or ii criteria 65 99% of time and during the cooling season 64 100% of time. average co2 levels were in the acceptable level, table 4. fig. 4 indoor air quality results during heating season fig. 5 indoor air quality results during cooling season table 4 average co2 levels and ventilation air flow during occupancy period in studied day-care centres co2 level during occupancy, ppm occupant (satisfaction), % estonia 1 estonia 1 finland 1 finland 2 norway heating season 547 808 501 553 497 cooling season 516 496 410 424 359 day-care centre en 15251 classification: estonia 1 estonia 2 finland 1 finland 2 norway day-care centre en 15251 classification: estonia 1 estonia 2 finland 1 finland 2 norway fig. 5 indoor air quality results during cooling season. table 4. average co2 levels and ventilation air flow during occupancy period in studied day-care centres. co2 level during occupancy, ppm occupant (satisfaction), % estonia 1 estonia 1 finland 1 finland 2 norway day-care centre en 15251 classification: estonia 1 estonia 2 finland 1 finland 2 norway fig. 5 indoor air quality results during cooling season. occupant surveys the overall indoor environment was very good as occupant satisfaction was 90% or more, table 5. table 5 summary of occupant satisfaction with the indoor climate occupant (satisfaction), % estonia 1 estonia 2 finland 1 finland 2 norway overall indoor environment 100 100 94 93 90 thermal environment 100 100 100 82 90 indoor air quality 100 100 88 100 80 illuminance level 100 100 100 100 100 acoustic level 100 100 100 88 91 odour intensity 100 100 81 94 90 13 journal of sustainable architecture and civil engineering 2019/1/24 table 6 presents annual delivered and primary energy use in the studied day-care centers. energy use in the norwegian day-care center was lower than designed. in other day-care centers this was contrariwise. the energy performance certificate was two to four classes lower in the studied buildings, fig. 6 left. the performance gap varied between 25 % 67% and it was larger in more energy efficient buildings, fig. 6 right. energy performance table 6 annual energy use in studied day-care centres energy use, kwh/(m2 a) estonia 1 estonia 2 finland 1 finland 2 norway delivered energy designed 146 45 133 71 71 measured 202 125 327 121 46 performance gap 28% 64% 59% 41% -54% energy performance value (primary energy) designed 189 83 169 152 measured 251 249 401 258 performance gap 25% 67% 58% 41% measured real energy use was higher, or even significantly higher, than the energy use calculated during the design phase. raide et al. (2015) monitored and simulated performance of energy use, indoor climate, and building service systems of the day-care center that was designed according to passive house standards. buildings did not meet the desired levels because of a lack of robust project leadership and final component selection. because of a too simplified control of building service systems and over optimistic and inadequate assumptions in energy calculations and initial data, energy performance targets were not realised. the energy performance gap was larger for more energy efficient buildings. when energy use is small, then small changes may cause a large relative difference. arumägi and kalamees (2016) showed that in designing of very energy efficient buildings, more thorough analyses are needed in the very first stage of the design, to find suitable solutions and possible compromises. if, in today’s design practice, during the preliminary design phase, only minor analysis is done, then design practice should change when moving towards nzeb. norwegian day-care center that was designed, constructed and commissioned according to passive house standards fulfilled epc promises. even more – measured real energy use was smaller fig. 6 comparison between designed and real measured energy performance certificate (left) and dependence of performance gap on designed energy performance certificate in buildings where energy performance targets were not fulfilled table 6. annual energy use in studied day-care centres. energy use, kwh/(m2 a) estonia 1 estonia 2 finland 1 finland 2 norway delivered energy designed 146 45 133 71 71 measured 202 125 327 121 46 performance gap 28% 64% 59% 41% -54% energy performance value (primary energy) designed 189 83 169 152 measured 251 249 401 258 performance gap 25% 67% 58% 41% fig. 6 comparison between designed and real measured energy performance certificate (left) and dependence of performance gap on designed energy performance certificate in buildings where energy performance targets were not fulfilled discussion measured real energy use was higher, or even significantly higher, than the energy use calculated during the design phase. raide et al. (2015) monitored and simulated performance of energy use, indoor climate, and building service systems of the day-care center that was designed according to passive house standards. buildings did not meet the desired levels because of a lack of robust project leadership and final component selection. because of a too simplified control of building service systems and over optimistic and inadequate assumptions in energy calculations and initial data, energy performance targets were not realised. the energy performance gap was larger for more energy efficient buildings. when energy use is small, then small changes may cause a large relative difference. arumägi and kalamees (2016) showed that in designing of very energy efficient buildings, more thorough analyses are needed in the very first stage of the design, to find suitable solutions and possible compromises. if, in today’s design practice, during the preliminary design phase, only minor analysis is done, then design practice should change when moving towards nzeb. norwegian day-care center that was designed, constructed and commissioned according to passive house standards fulfilled epc promises. even more – measured real energy use was smaller than discussion journal of sustainable architecture and civil engineering 2019/1/24 14 than designed. a more accurate and robust commissioning, design and construction process is needed for future nzeb day-care centers. the exact reason of higher energy use was difficult to determine. the total energy use was measured, but there lack detailed and separated energy measuring of energy use in smaller subdivision. for future nzeb day care centers we recommend measuring separately: _ heat consumption for room heating, heating of ventilation air, heating of dhw, _ electricity consumption for fans-pumps, appliance-lightning, cooling _ on-site energy production: heat, electricity. potential reasons for the higher measured energy use are caused by the methodology of the energy calculations and the differences in user behavior. some of the appliances, which may have a significant share of the buildings overall energy consumption, like hot kitchens, missing of heat recovery unit in kitchens, swimming pools, and outdoor lighting, are not taken into account in the energy calculations. indoor temperature during the heating season tended to be higher than the +21 ºc used in the energy calculations. measurements showed that occupants preferred an indoor temperature around +22…+23 ºc. also usage activity and occupant density influence energy use. sekki et al. (2015) studied day-care centers in finland and showed that the more m2/child, the more energy the building consumes (even then, there were great variations between the buildings (sekki et al., 2015b)). therefore, we recommend making energy simulations based as much as possible on the future building’s usage profile, as well as standard simulations. the designed delivered energy use in finnish day care center 2 was 71 kwh/(m2∙k). sankelo et al. (2018) showed that with the similar initial investment cost it would be possible to reach to much lower energy use and cost optimal levels for day-care centres lie on 35 – 40 kwh/(m2∙k) for buildings with gshp and 70 – 80 kwh/(m2∙k) for buildings with district heating. thermal environment corresponded to the climate categories i and ii better during heating season. during summer season the room temperature was too cool mainly because of low spring-summer period. even though measured ventilation air flow rates did not fulfill designed values, based on co2 levels, indoor air quality targets were fulfilled most of the time. this indicates that window airing was used to compensate for missing ventilation airflow. window airing does not provide any heat recovery or filtration possibilities. this could cause a deterioration of indoor air quality (depending on the location of the building) and energy performance. conclusions indoor climate condition measurements showed that, in general, the thermal environment and indoor air quality in 5 modern day-care centres in estonia, finland and norways corresponded to the highest indoor climate categories i and ii (en 15251). building heating and ventilation systems in the studied buildings are working without major problems. good indoor climate conditions were also reflected in the occupant satisfaction questionnaires. for most of the studied buildings, over 80% of the people marked all indoor environment condition parameters (thermal comfort, indoor air quality, acoustics, odour and illuminance) as acceptable. energy consumption analysis showed that problems exist between the calculated and measured values. in most of the studied buildings, measured energy consumption is higher or even significantly higher than designed values. potential causes of the higher actual energy consumption are caused by differences between measured and designed solutions, the methodology of the energy calculations and the differences in user behaviour. some of the appliances, which may have a significant share of the buildings overall energy consumption, like hot kitchens, swimming pools and outdoor lighting are not taken into account in the energy calculations. indoor temperature in the heating season tended to be higher than the 21 ºc used in the energy calculations. measurements showed that occupants prefer an indoor temperature of around 22…23 ºc. 15 journal of sustainable architecture and civil engineering 2019/1/24 this research utilises measurement data from h2020 project no 754177: “nero cost reduction of new nearly zero-energy wooden buildings in the northern climatic conditions”. the research was co-financed by the estonian research council with personal research funding prg483 “moisture safety of interior insulation, constructional moisture and thermally efficient building envelope”, institutional research funding grant iut1-15, estonian centre of excellence in zero energy and resource efficient smart buildings and 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veld, p.o. ‘t, kuusk, k., silva, s., 2016. what kind of heat loss requirements nzeb and deep renovation sets for building envelope?, in: central europe towards sustainable building 2016: innovations for sustainable future, cesb 2016. university centre for energy efficient buildings czech technical university in prague, 22– 24 june 2016 prague, czech republic, pp. 137–144. kolarik, b., andersen, z.j., ibfelt, t., engelund, e.h., møller, e., bräuner, e.v., 2016. ventilation in day care centers and sick leave among nursery children. indoor air 26, 157–167. https://doi.org/10.1111/ina.12202 kurnitski, j., ahmed, k., hasu, t., kalamees, t., lolli, n., lien, a., johan, t., jan, j., 2018. nzeb energy performance requirements of four north ... against official recommendations of european commission, in: proceedings of the rehva annual meeting conference low carbon technologies in hvac. 23 april 2018, brussels, belgium, p. 8. kylili, a., fokaides, p.a., seduikyte, l., 2016. sustainability tools for the assessment of construction materials and buildings. journal of sustainable architecture and civil engineering 16, 61–69. https:// doi.org/10.5755/j01.sace.16.3.16172 levinskyte, a., banionis, k., geleziunas, v., 2016. the influence of thermal bridges for buildings energy consumption of “a” energy efficiency class. journal of sustainable architecture and civil engineering 15, 47–58. https://doi.org/10.5755/j01.sace.15.2.15351 journal of sustainable architecture and civil engineering 2019/1/24 16 raide, i., kalamees, t., mauring, t., 2015. lessons learnt from the first public buildings in estonia intended to be passive houses. proceedings of the estonian academy of sciences 64, 157. https://doi. org/10.3176/proc.2015.2.04 sankelo, p., jokisalo, j., nyman, j., vinha, j., sirén, k., 2018. cost-optimal energy performance measures in a new daycare building in cold climate. international journal of sustainable energy 1–19. https://doi.org/10.1080/14786451.2018.1448398 sekki, t., airaksinen, m., saari, a., 2015a. impact of building usage and occupancy on energy consumption in finnish daycare and school buildings. energy and buildings 105, 247–257. https://doi. org/10.1016/j.enbuild.2015.07.036 sekki, t., airaksinen, m., saari, a., 2015b. measured energy consumption of educational buildings in a finnish city. energy and buildings 87, 105–115. https://doi.org/10.1016/j.enbuild.2014.11.032 zavadskas, e.k., antucheviciene, j., kalibatas, d., kalibatiene, d., 2017. achieving nearly zero-energy buildings by applying multi-attribute assessment. energy and buildings 143, 162–172. https://doi. org/10.1016/j.enbuild.2017.03.037 kalle kuusk senior research scientist tallinn university of technology, estonia main research area energy performance of buildings address ehitajate tee 5, tallinn e-mail: kalle.kuusk@taltech.ee jan johansson energy manager växjö kommun, sweden main research area energy performance of buildings address västra esplanaden 18, växjö e-mail: jan. johansson3@vaxjo.se endrik arumägi senior research scientist tallinn university of technology, estonia main research area energy performance of buildings address ehitajate tee 5, tallinn e-mail: endrik. arumagi@taltech.ee jarek kurnitski adjunct professor aalto university, finland main research area energy performance of buildings address otakaari 1 b, espoo e-mail: jarek.kurnitski@aalto.fi ahmed kaiser doctoral candidate aalto university, finland main research area energy performance of buildings address otakaari 1 b, espoo e-mail: kaiser.ahmed@aalto.fi nicola lolli research scientist sintef, norway main research area energy performance of buildings address strindveien 4, trondheim e-mail: nicola.lolli@ sintef.no tero hasu specialist kouvola innovation ltd., finland main research area energy performance of buildings address paraatikenttä 4, kouvola e-mail: tero.hasu@kinno.fi anne gunnarshaug lien senior research scientist sintef, norway main research area energy performance of buildings address strindveien 4, trondheim e-mail: anne.g.lien@ sintef.no kristo kalbe expert tallinn university of technology, estonia main research area energy performance of buildings address ehitajate tee 5, tallinn e-mail: kristo.kalbe@ taltech.ee jaanus hallik doctoral candidate tallinn university of technology, estonia main research area energy performance of buildings address ehitajate tee 5, tallinn e-mail: jaanus.hallik@ taltech.ee targo kalamees professor tallinn university of technology, estonia main research area energy performance of buildings address ehitajate tee 5, tallinn e-mail: targo. kalamees@taltech.ee about the authors 35 journal of sustainable architecture and civil engineering 2019/2/25 *corresponding author: lars.gullbrekken@sintef.no towards upgrading strategies for nzeb-dwellings in norway received 2018/11/15 accepted after revision 2019/05/02 journal of sustainable architecture and civil engineering vol. 2 / no. 25 / 2019 pp. 35-42 doi 10.5755/j01.sace.25.2.22067 towards upgrading strategies for nzebdwellings in norway jsace 2/25 http://dx.doi.org/10.5755/j01.sace.25.2.22067 lars gullbrekken*, berit time sintef building and infrastructure, trondheim, norway introduction recent work suggests that upgrading in line with the norwegian building regulations or by upgrading to the requirements of the national passive house norm, ns3700, can enable nzeb level to be achieved. the aim of this work is to explore the typical norwegian housing typologies and some important characteristics of the building envelope for these houses from different decades. the exploration involved surveying the typical technical qualities of norwegian housing and how these have evolved – providing an important foundation to work addressing strategies and methods for upgrading dwellings to nzeb level in the next phases of the ongoing research project. the results of this work show that the building norms and practices developed throughout the years have made dwellings more moisture resilient, with an increased drying-out potential through mechanical ventilation, control of the air change rate and the use of more vapour-open wind barriers in the building envelope. based on this, the work to follow will suggest strategies for upgrading to nzeb level, solutions for upgrading building envelope components to high performance level and a methodology for risk reduction of moisture problems in the upgraded dwellings from the different decades. keywords: building physics; moisture resilience; energy upgrading of buildings; nzeb; dwellings. norwegian tradition of wooden houses norwegian residential buildings are largely detached wooden houses, 60% of which are detached houses built between 1960 and 1990 and are by now 30–60 years old. (sentralbyrå., 2010.) this building stock is now rapidly reaching a stage where major renovations need to take place. the annual number of new dwelling units passed 40,000 in the period from 1970 to 1975. in comparison, the dwelling stock increased by 32,000 in 2017 (ssb, 2018). the large number of completed detached houses in the 1960s, 1970s and 1980s, together with strict rules from the norwegian housing bank for obtaining mortgages, have led to the building typology of this period being quite homogeneous (see fig. 1). the population of detached houses often consist of a concrete or masonry basement. further, the houses have a wood-frame exterior wall construction with mineral wool insulation, and a wooden exterior cladding. the building envelope and technical system are less energy efficient than similar houses of today and hence, a potential for energy saving renovation exists (risholt, 2013). some examples of the development of the prefabricated houses are given in table 1. journal of sustainable architecture and civil engineering 2019/2/25 36 fig. 1 dwellings units completed in the period from 1951 to 1993. the results are sorted by type of house: one-family houses, divided small houses and large houses. (myhre, 1995) table 1 typical examples of the development of prefabricated houses from 1950 to 1990 (støa, 2018) 1945–1960 post-war houses 1960–1970 prefabricated houses 1970–1980 second-generation prefabricated houses 1980–1990 architectural release (photo: systemhus) 37 journal of sustainable architecture and civil engineering 2019/2/25 towards nzeb upgrading actions to reduce the greenhouse gas emissions from buildings are important, since buildings account for 10% of global co2 emissions (agency, 2010). according to the the european union directive 2010/31 (council, 2010) and norwegian government (kmd, 2017), all new buildings should be built according to nzeb level by 2020. . risholt (2013) has demonstrated that this is possible also for upgrading of dwellings, in theory, and lien et al. (2017) in practise. to save energy in the building sector, it is necessary to increase the focus on upgrading of the existing building stock. according to risholt (2013), the energy use of norwegian single-family houses was 30 twh in 2009. by upgrading the building envelope of detached houses built before 1990, a potential energy saving of 8 twh was found. risholt (2013) studied the possibility of renovating a norwegian single-family house to become a zero energy building (zeb) while at the same time meeting cost and quality requirements. she focused on single-family houses built in the 1980s and found that norwegians spend huge sums of money on the upgrading of kitchens and bathrooms. some of the houses were already renovated; however, no correlation was found between the number of building defects and the renovation status. two possible strategies for renovating to zero energy standards were identified. the first option was the façade solution, which included upgrading the thermal properties of walls, windows and doors as well as installation of balanced ventilation and renewable energy production on site (e.g bipv). the second option was a more ambitious strategy, which included upgrading of the building envelope to passive house level, installation of ventilation and renewable energy production on site (e.g bipv). the renovation of most wooden dwellings aims for energy levels that are similar to the original standard; this often happens because of poor energy advice(risholt, 2013). only half of the renovations taking place in norway include energy renovation. (risholt, 2013)( bjørnstad 2015). building components have a service life of 30–50 years and are typically only replaced when needed, we therefore may risk “energy lock-in” if, for example, the cladding is replaced without adding insulation at the same time, or if the roofing is replaced without extending the overhang and preparing for additional wall insulation. along with energy advises we also experience a need for generic moisture safety advises. in upgrading projects, insulation on the exterior face of the construction often creates typical questions like: “what is required on the internal side of the construction?” or “is the airtightness and the vapour resistance of the existing vapour barrier and internal layers high enough to avoid problems?” today there exist no tools that can give a straight answer to this question without assessing the construction in each individual case. some relevant information exists, but the information is scattered and several sources have to be used. aim of work the aim of this work has been to explore the typical norwegian housing typologies and some important characteristics of the building envelope for housing from the different decades studied. the exploration involved the surveying of the typical technical qualities of norwegian housing, looking into how these have evolved over the years. this forms an important foundation to work addressing strategies and methods for upgrading dwellings to nzeb level in the next phases of the ongoing research project. methodsthis study is conducted primarily as a literature and document study. norwegian building rules1 from the last 60 years have been used, as has the norwegian knowledge system byggforskserien (the building research design sheets) and trehusboka (the nor1 norwegian building rules from 1965-2017 available from: https://www.regjeringen.no/no/tema/plan-bygg-og-eiendom/ bygningsregelverket-fra-1965--20172/bygningsloven/id2590707/ journal of sustainable architecture and civil engineering 2019/2/25 38 wegian wooden house book). norwegian technical approvals for building products over the last 30 years have also been used. a technical approval indicates that a construction product is considered to be suitable for use and meets the requirements of the building regulations for the uses and conditions specified in the approval document. trehusboka (granum h, lundby se, 1952) is a reference series for wooden houses in norway and was first published in 1952. the following versions of trehusboka have been reviewed and applied this work: 1952, 1958, 1961, 1965, 1970, 1980, 1990, 1997, 2007. the book has been in line with practise throughout the years and the continuous update of trehusboka makes it a unique reference series. byggforskserien2 is a series of documented solutions for those who build, run projects and manage buildings in norway. byggforskserien has co-existed with the norwegian building rules and building practises for 60 years and is the most widely used system for building engineering solutions in norway. the solutions in byggforskserien have always been better than, or according to, the building regulations. instructions in byggforskserien therefore show and document the development of regulations and technical solutions and are a unique source for studying (the technical) development of norwegian housing models. the study is limited to norwegian dwellings, but it is likely that the study and findings herein will have a great transfer value to other countries with a long history of wooden houses. building regulations development for thermal insulation according to myhre (1995), the main purpose of the norwegian building regulations of 1949 was to provide a satisfactory indoor climate. the requirements of 1965 barely even involved updating the thermal insulation level to that already commonly practised in construction (granum, 1989). however, the thermal insulation level requirements were tightened in 1985. during the 1980s it was common to construct walls with 150 mm thick insulation and roofs with 200 mm thick insulation. windows with low emission layers gained market share during the same period (granum, 1990), as shown in table 2. table 3 shows how the insulation levels recommended by the norwegian building research institute have steadily increased in the period from 1952 to today. building part 1949 1965 1985 1987 tek97 tek07 tek10/tek17 * * ** wall [w/m²k] 0.70– 1.05 0.46– 0.58 0.35 0.30 0.22 0.18 0.18 0.22 window [w/m²k] 2.7 2.4 1.6 1.2 0.80 1.2 door [w/m²k] 2.0 2.0 1.6 1.2 0.80 1.2 roof [w/m²k] 0.70– 1.05 0.41– 0.46 0.23 0.20 0.15 0.13 0.13 0.18 basement walls [w/m²k] 1.16– 1.86 1.57– 2.33 0.8 0.8 0.22 0.18 0.18 0.22 floor towards external air [w/m²k] 0.41– 0.46 0.23 0.20 0.15 0.15 0.10 0.18 slab on ground [w/m²k] 0.3 0.30 0.15 0.15 0.10 0.18 window area [m²/ m² heated area] 0.15 0.2 0.2 0.2 0.25 0.25 air change rate, n50 [1/h] at 50 pa 4 4 4 2.5 0.6 1.5 *energy measures method. **minimum requirements for the building part, which imply stricter requirements for other building parts to fulfil the overall energy norm. 2 byggforskserien available at https://www.byggforsk.no/ table 2 technical minimum demands for energy performance/thermal insulation given for building envelope parts according to the norwegian building regulations throughout the studied years. tek97 means 1997 and so on 39 journal of sustainable architecture and civil engineering 2019/2/25 discussion from the beginning of the 1950s it was considered profitable to use mineral wool insulation in roof and wall constructions instead of the old materials such as clay and sawdust (granum and lundby, 1952). by the end of the 1950s, most houses were constructed with mineral wool insulation in the outer constructions (myhre, 1995). the thermal conductivity of the mineral wool has been lowered from 0.041 w/mk in 1958 down to today’s value of 0.031-0.034 w/mk. vapourand wind barrier moisture characteristics a moisture-safe wood-frame construction assumes a low vapour and air permeability on the internal, warm face of the construction and a high vapour permeability on the external, cold face of the construction (thue et al., 1996; vinha, 2007). based on laboratory measurements on insulated wood-frame walls with different insulation materials and different vapour barrier vapour permeabilities, thue et al. (1996) recommend the use of pe-foil as a vapour barrier. further, a ratio between the diffusion resistances of the wind barrier and the vapour barrier larger than ten was recommended in order to avoid interstitial condensation problems. in addition, a moisture-safe construction assumes a vapour-open wind barrier in order to dry out excessive moisture. table 4 shows the vapour diffusion resistance of the typical materials/product categories used for wind and vapour barriers in the period 1960–2007. for some of the values a span in reported. in these cases the vapour diffusion resistance is varying with the thickness of the material. table 3 recommendations given in byggforskserien regarding technical demands energy performance/ thermal insulation for building envelope parts throughout the studied years. empty cells mean no distinct recommendations table 4 vapour diffusion resistances (sd-values) for typical materials/ product categories used for vapourand wind barriers in the period from 1960 to 2007. cited from byggforskserien, trehusboka and technical approvals. empty cells means that no value has been found in the references building part 1950–1970 1970–1980 1980–1990 1990–2000 wall [w/m²k] 0.30 0.30 0.30 0.18 window [w/m²k] 2.4 1.2 door [w/m²k] 2.4 1.2 roof [w/m²k] 0.30 0.30 0.23 0.15 floor towards external air [w/m²k] 0.30 0.30 0.23 0.15 slab on ground [w/m²k] 0.30 0.15 window area [m²/m²] 0.15 0.20 air change rate (at 50 pa) [1/h] 4 material 1960 1970 1980 1990 2007 recommendation vapour barrier >10 m >10 m >10 m >10 m > 10 m plastic-coated cardboard 50 m 10-15 m plastic foil, polyethylene 15–30 m 25-100 m 70–100 m 70–100 m asphalt-coated cardboard 15 m 15 m 20 m recommendation wind barrier < 1.9 m < 1.9 m < 1.9 m < 1.7 m < 0.5 m impregnated fibre boards 0.1-0.4 m 0.1-0.4 m 0.2-0.3 m 0.2-0.3 m gypsum board 13 mm < 0.1 m < 0.1 m 0.1–0.15m < 0.1 m wind barrier foils < 0.1 m < 0.1 m building envelope thermal insulation development since 1950, there have been increasingly strict building regulations concerning the technical demands for building parts. in recent decades the revisions have been more frequent but the minimum demands for heat insulation of building parts have, to a large extent, been constant since journal of sustainable architecture and civil engineering 2019/2/25 40 1987. however, during this period, the requirement for the air change rate of the building envelope has been lowered from 4 to 1.5 h-1 (at 50 pa pressure difference). the requirement for high-performance heat recovery of the ventilation air was added in 2010, requiring balanced ventilation (an improved mechanical ventilation system where both the air inlet and outlet are controlled by fans). the frequent revisions during the 2010s can be explained by an increased focus on energy use in buildings – by the norwegian government in particular. during this period, the norwegian passive house standard was developed and was first published in 2010 (ns3700, 2010). ventilation strategies throughout the years heat loss from infiltration and ventilation represented about one-third of the total heat loss from a typical detached one-family houses built before 1990 (granum, 1990). as table 2 shows, no requirements for air infiltration through the building envelope were given before 1987. air leaks in the outer part of the construction are referred to as infiltration. the infiltration rate varies by local wind conditions, type of building, type of construction and craftmanship. natural ventilation strategies, where the air exchange is driven by thermal buoyancy, were common in small houses up to about 1980. from 1980 it was more common to install mechanical ventilation systems in new dwellings. these systems have fans, which drag air out of the building, providing steadier ventilation rates compared to natural ventilation systems (myhre, 1995). during the late 1990s and early 2000s, it became increasingly common to install balanced ventilation systems, even in small houses. a heat recovery unit makes it possible to utilise the energy content of the outlet air. as a result of increasingly strict demands for building infiltration during the 2010s, the focus on infiltration through the building envelope has increased. according to tek 17 (2018), the maximum limit of air infiltration is set to 1.5 air changes per hour at 50 pa pressure difference. the increasing focus on building infiltration has led to a positive focus on air tightening, especially air tightening of the wind barrier. an airtight wind barrier is, together with an airtight vapour barrier, not only a measure to save energy, but also a measure to avoid building defects caused by, for example, convection of warm, humid indoor air through the structure (langmans et al., 2010; gullbrekken et al., 2016). development of building products according to the early editions of trehusboka from 1952 and through the decades that followed, different types of cardboard were used both for the vapour and wind barrier. plastic-coated cardboard was used as a vapour barrier and asphalt-coated cardboard was used as a wind barrier. concerning vapour diffusion resistances for vapour barriers, the recommendations in the different editions of trehusboka and byggforskserien have been constant from 1950 to today. the recommendations concerning vapour diffusion resistances for the wind barrier were constant from 1950 to 2007. in 2007 the recommendations were lowered to one-quarter of the existing demands. findings in the studies of (thue et al., 1996; vinha, 2007), as well as the increased typical wall insulation thickness (from 150 mm to 200 mm), implied a need for larger dry-out capacity due to the increased amount of wood and hence an increased possibility of built-in moisture. new building products were introduced, including large-format wind barrier foils which entered the norwegian market during the 1990ies. these new products had a higher water vapour permeability (e.g sd-values from 0,02-0,06 m) compared to the traditional wind barriers and the use of large-format rolls made it easier to achieve high air-resistance performance. measures – moisture safety and energy performance an nzeb upgrading of a dwelling implies a need to focus on additional insulation on the exterior or interior face of the existing construction and the overall consequences of this. the upgrading measures can often be performed in different steps. in order to secure high architectural and technical performance, joints between the different building parts have to be planned. one typical practical example is that additional exterior wall insulation affects the roof overhang of the specific 41 journal of sustainable architecture and civil engineering 2019/2/25 conclusions building and should be accounted for when the roof is upgraded. in addition to lowering energy consumption, the addition of insulation in different building parts is increasing the moisture mould growth potential of these constructions in general (gullbrekken et al., 2015). however, by replacing the existing wind barrier with a modern product (vapour open foil), the vapour resistance of the wind barrier is lowered and the dry-out potential of the construction increases. in addition, these modern wind barriers often imply a lower air permeability of the construction, which increases the moisture robustness (relander, 2011). installation of balanced ventilation is lowering the humidity level of the internal air and hence further increasing the moisture robustness of the construction. such actions are of great importance both for the builders and the owners. a risk assessment tool based on fault tree analysis could be applied and a way forward, considering the moisture safety of the existing and upgraded solution to make it easier to get a simplified overview of the situation and to make correct choices for different constructions. the general method is described in iec 61025 (2006). previously, (arfvidsson et al., 2016) presented a method for risk analysis of energy upgrading of historical buildings. the method included measurements and assessments of each specific building. in order to give practical advice to the building industry, a more general assessment method is needed, one that focuses on energy upgrading of small norwegian houses built in the period 1950–1990. a considerable proportion of detached houses from the 1960s and 1970s have already been upgraded to some extent – the implications of this must be included in the risk assessment tool. in order for a building to reach nzeb level, the heat loss through the building envelope needs to be relatively small, and the building likely needs to be equipped with energy producing products. the nzeb level is still being debated internationally and is not yet defined. the research project of which this work is a part, is aiming at making a definition of nzen level for upgrading of dwelling. anyhow, the energy consumption and production must be documented. however, there is a question of how much extra insulation the different building parts need. according to the study of risholt (2013), façade improvements have higher impact on the heat loss than improvements to other building parts. this is confirmed in the study of skeie et al. (2014) and is mainly explained by improved airtightness and hence lowered infiltration loss (skeie et al., 2014). according to skeie et al. (2014), improvement of the u-value of windows or reduction of the window area, is the single building envelope improvement measure that has the largest energy saving potential. further, a description of a three-step upgrading of the building envelope of existing detached houses from the 1960s, 1970s and 1980s is presented in lien et al. (2017). this three-step method includes the upgrading of the roof construction, exterior wall construction and floor construction. the study of lien et al. 2017 includes upgrading up to the current norwegian building regulations (tek17) and to the norwegian passive house requirements (ns3700). however, upgrading to tek17 level requires installation of more renewable energy production compared to the ns3700 level in order to fully balance the energy consumption. previous work suggests that upgrading to nzeb level can be reached by upgrading in line with the norwegian building regulation or by upgrading to the requirements of ns3700. however, dependent on the definition of nzeb, upgrading to the current building regulations requires installation of renewable energy production on the dwelling in order to fully balance the energy consumption (zero energy building level). the results of this work show that building norms and practices throughout the years have made dwellings more moisture resilient, with an increased drying-out potential through mechanical ventilation, control of the air change rate and more vapour-open wind barriers in the building envelope. based on this survey, the work to follow will suggest strategies for upgrading to nzeb level, solutions for upgrading building envelope components to high performance level and a methodology for risk reduction of moisture problems in the upgraded dwellings from the different decades. journal of sustainable architecture and civil engineering 2019/2/25 42 acknowledgements this paper has been written within the research project “energy upgrading of wooden dwellings to nearly zero energy level” (opptre). the authors gratefully acknowledge the support from the opptre partners and the research council of norway. references agency ie. 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(2018) presentation in the research project opptre. 03.09.2018. trondheim. tek17 (2018) forskrift om tekniske krav til byggverk (in norwegian). lovdata. visited 06.11. 2018 https:// lovdata.no/dokument/sf/forskrift/2017-06-19-840 thue jv, skogstad hb, et al. (1996) wood frame walls in cold climate – vapour barrier requirements. journal of thermal insulation and building envelopes 20: 63–75. https://doi. org/10.1177/109719639602000106 vinha j. (2007) hygrothermal performance of timber-framed external walls in finnish climatic conditions: a method for determining the sufficient water vapour resistance of the interior lining of a wall assembly. phd-thesis. tampere university of technology. about the authors lars gullbrekken phd, researcher sintef building and infrastructure main research area building physics address høgskoleringen 7b 7046 trondheim berit time phd, chief scientist sintef building and infrastructure main research area building physics climate adaptation address høgskoleringen 7b 7046 trondheim https://www.ssb.no/bygg-bolig-og-eiendom/artikler-og-publikasjoner/storste-boligvekst-pa-tolv-ar https://www.ssb.no/bygg-bolig-og-eiendom/artikler-og-publikasjoner/storste-boligvekst-pa-tolv-ar https://www.ssb.no/bygg-bolig-og-eiendom/artikler-og-publikasjoner/storste-boligvekst-pa-tolv-ar 51 water designing for sustainability, purity and comfort niki manou-andreadis, maria milona* aristotle university of thessaloniki faculty of engineering school of architecture, 22, tritis septemvriou ave, gr-54636, thessaloniki, greece . *corresponding author: m.milona@nimand.gr http://dx.doi.org/10.5755/j01.sace.4.5.4722 the objective of this paper is to present designs involving water and architecture and explore this dual impact that water has on human lives and the environment. on one hand, architects use materials and forms to communicate ideas, while at the same time the use of water elements could become a point of gathering, a source of power, a place of culture and reflection, or a place of imagination. many examples of history will be mentioned, where connections among people, water and environment were fortified. for example, in ancient greece, “balaneion” was called the bath, where all social events were discussed and sometimes many philosophical declamations took place. people need connections to the past in order to help them make some sense of the increasingly complex world. nowadays, sustainable architecture encourages the use of water for many environmental and social reasons. water could be effective at cooling interior spaces, and when combined with plants it could provide natural air conditioning. this paper will highlight some recent innovations, which we have already accomplished on our projects. the use of vertical wall of plants and waterworks is able to enhance interior spaces and provide comfort to their users by achieving energy efficiency and at the same time creating positive impacts on health, safety and community welfare. in a holistic view, sustainable architecture could be an interconnected network of natural and social systems that provides a diverse range of environmental, cultural and economic benefits. keywords: greek baths “balaneion”, sustainable architecture, sustainable tourism development, water features. 1. introduction water can enliven architecture and then both of them could create unique and unusual projects. the purpose of this paper is to identify the meaning of integrating water in our architectural design not only for aesthetic purposes but also for environmental too. since recently global world has confronted many challenges due to climate change, architects should adopt and develop a sustainable approach. sustainable architecture should consider how to use water, how to use this vital element which is mysteriously beautiful when combined in architectural designs. these days, more than ever, that water supply becomes increasingly scarce in many regions, such as the mediterranean and particularly greece – where our studied projects took place –, that suffer from droughts and have experienced increased levels of irrigation, architects could use in their designs recycled water devices. due to the continuous progress of technology, once again, architects should take the responsible role of balancing this relationship between people’s actions and natural resources. more specifically, the rhythms of human beings on the one hand and nature on the other hand are driven totally separate. according to brundtland report, “any development should meet the needs of the present without compromising the ability of future generations to meet their own needs” (brundtland 1987). therefore, it is urgent to look back in history where many examples of architecture integrated with water can be noticed and evaluate this relationship in order to comprehend the meaning of those two elements, which contribute to creating sustainable communities. 2. methods the methodology of the research would try to emphasize the relationship of architecture and water in order to realize and evaluate how these two elements could be interconnected. more specifically, it is essential to underline that sustainable architecture could promote the interaction of environmental, socio-cultural and economic issues in order to preserve nature and provide welfare to social communities as well as to protect cultural heritage and eventually to provide economic growth for people, respectively. subsequently, the use of water could contribute darnioji architektūra ir statyba 2013. no. 4(5) journal of sustainable architecture and civil engineering issn 2029–9990 52 on all the aforementioned sustainable aspects either by cooling particular areas or by creating emotions and featuring as a meeting point so as to encourage connections among people, water and environment. the research will point out: a) the significance of water over many centuries and especially its implementation in ancient greek baths in order to understand the influences on our current designs, b) the analysis of literature studying concrete philosophers and architects and their views upon water, c) analysis of global trends related to sustainability in the tourism sector, which is characterized of leisure activities, in order to determine our intentions on applying water features on hotel resorts, d) the analysis of projects which have been completed in order to explore the integration of water into architectural proposals not only for aesthetic reasons but also for environmental, e) conclusions, where the key role of architects on sustainability issues is underlined and the importance of using that natural element, water, which contributes on obtaining environmental friendly buildings, creates welfare for social communities and leads on economic growth. 3. results 3.1. references of water in ancient greece: the case of “balaneion”. in previous centuries architecture was organized in relation to water, such examples are baths and spas in ancient greece. more specifically, “balaneion” implies a bath, which was too popular in greek culture and society. according to bonneville “the history of public baths begins in greece in the sixth century b.c. (bonneville 1994). it is where the greek community has exercised both physically and intellectually. over years, this communal and almost daily activity, bathing, was evolved as a high art as people were socialized, gathered and relaxed over these community centers. furthermore, public baths have been integrated into the social system as meeting points. many ancient greeks organized social events with their friends or colleagues, philosophers gave their declamations, even politicians attempted to get closer with their voters in order to influence them for their causes. sometimes, these baths accommodated various other spaces, such as libraries as well as restaurants. therefore it is obvious, that greek baths became focal points for social and recreational activity. “balaneion” and its architecture became a precursor for current spa centers, as we will conceptualize further on through the description of particular projects. 3.2. the significance of water. in many cases, architects achieve to integrate water into the built environment forming it in such a way that there is no discrimination between these two elements. moreover, both of them, architecture and water, could motivate people to use their senses, as they create distinctive sights, sounds and touches. more specifically, sounds of water are variable; it could splash against things or could move around solid objects or it could even fall on a surface and create different forms every time. additionally, it can offer some connections with nature or eliminate noises that are not desirable. in this case, when the sound of water is almost inexistent, people could find emotional rescue and live some moments of relaxation and meditation. victor schauberger, an austrian naturalist, indicated this magical role of water in an undistributed environment, such as the austrian forests, by spending many years observing them (callum 1997). furthermore, according to thales of miletus and plato, two philosophers in ancient and classical greece respectively, “water would be the start of all things”. rivers and projects with water features can be found in all cultures. also, stephen crafti refers in his book h2o architecture, that the role of water is not just to impress visitors but when it is applied with skill and imagination, it can even strengthen architectural forms and provide environmental, social and economical benefits for the building’s users (crafti 2005). “water can be experienced in a whole variety of ways. it creates different kinds of atmosphere and moods that appeal to our feelings” (woodward 2005). finally, the reflection of water on different surfaces could give meaning to a building. it has the ability to add an element of imagination either by converting the solidity of a building material to a more temporary one, as well as it could fill shadows with light in many other cases. therefore, it is clear that water’s beauty is in its fluidity, transparency and reflexiveness. 3.3. waterworks contributing on sustainable tourism development. one of our main cooperations is related to touristic resorts, as various hoteliers assign us to design and apply sustainable solutions to them. we are aware that the tourism sector confronts many environmental impacts that occur due to climate change and decreased amount of natural resources. therefore, it is urgent for this industry to start taking responsibility in order to implement environmental, social and economic sustainability. these distinguished resorts should be characterized of an excellent designed environment in order to respond to global tourism pressures and market needs. also, they should contain leisure facilities, which incorporate features of natural beauty and satisfy visitor’s preferences, who seek for a unique holiday experience. water has been a prime motivator of leisure and we, as architects, should attempt to persuade the hotel shareholders that waterworks contribute at some point on the cooling effect and therefore should be integrated into our architectural proposals. that is why we proposed diverse artificial water facilities for every studied project in order to apply cooling devices, which would produce better quality and more comfortable indoor and outdoor environmental areas. at this point it should be mentioned that this conventional environmental control for closed spaces is called microspace environment creation while the placement of water facilities throughout outdoor spaces in order to create a wide range of thermal environments is called macro space. every project which is going to be analyzed has its own potential and our aim was to provide inspired solutions that fulfill the needs and wishes of both the customers and the hotel managers. in any case, all our architectural projects are characterized by a people-focused approach and highlight this relationship between the built environment and the natural environment with people’s best quality of 53 life. applying this natural element is essential, as water could invite someone to touch it. also it could captivate the eye at a distance as well as it could provide a refreshing sense. 3.4. a channel of water in lindian village, lardos, rhodes. first of all we will analyze a channel of water 260 m long, which has been designed among various complicated architectural arrangements in a hotel complex called “lindian village” that is situated in a greek island in the eastern aegean sea, rhodes (fig. 1). it was constructed in 2004 and was proposed not just for decorative and aesthetic reasons but also for environmental benefits. the channel takes advantage of the spring and summer breezes, which are frequent on the island, in order to improve the thermal comfort in the surrounding area. actually, we were aware that this channel of water could play a significant role in the landscape design of the project as it could be integrated among the proposed number of buildings constructed and present an intrinsic quality of movement and noise as well as of sparkle and coolness. especially, as rhodes is characterized of hot and dry climate, applying this water channel could offer either interesting walking and bicycle trails for people or even more a magnificent view which visitors could enjoy from their balconies. fig. 1. a channel of water in lindian village, rhodes, greece additionally, we were influenced of the fact that ancient greek cities were mostly developed near water so that societies were able to benefit with access to trade not only of products but also of ideas, including language, writing and technology. many cultural events were organized in the towns surrounding by those water features. therefore, it can be mentioned that a channel of water not only played an important role in country’s geography but also could be the life blood in contemporary greek civilization. 3.5. a water-wall in oceania club, nea moudania, halkidiki. the second project which is going to be presented is a water wall designed in 2005 for a hotel “oceania club” situated in northern greece (fig. 2). this external water wall, 15.50 m long and 12 m high, covers a high retaining wall and is directly revealed since it is a welcoming element for the guests visiting the swimming pools and at the same time it is a way to allow a cooling breeze to circulate. in addition, it was designed to provide as natural a space as possible, where visitors could relax and at the same time experience the various aspects of water, such as the swimming pools, the sea and the water wall. also, the reflective quality produced provides a seductive logic and charm while at the same time it creates interesting sounds. in terms of the cooling effect, it can be said that these types of water elements contribute on an improvement on the thermal comfort of the visitors. according to many studies water walls present a lower albedo than other building materials used. therefore, they can play a key role in the overall design concept, especially in resorts situated in coastal areas as they could take advantage of the sea breeze effect too. fig. 2. a water-wall in oceania club, halkidiki, greece 3.6 water features in sani beach club, sani, halkidiki. the next which will be analyzed is a project completed in 2010 which reveals the construction of a spa center in “sani beach club” situated in northern greece. in this case, water has been used in the reception area of the center both for reference to the history of spas in ancient greece and also, for environmental purposes as it provides a spot of coolness and serenity for the visitors as soon as they enter the building. more specifically, water runs over a glass of 260 mm height and 360 mm width and forms rhythmic patterns by running down through the whole surface (fig. 3). fig. 3. a water-wall in sani beach club, halkidiki, greece according to greek history, in mid-2nd millenium bc many bathing practices such as small bathtubs, wash basins 54 and foot baths took place at knossos, crete as well as in akrotiri, santorini. those public baths, which contributed on people’s hygiene and relaxation consist the foundation for current modern spa facilities. furthermore, hippocrates (460-370 bc), the most celebrated physician of antiquity, underlined the significance of thermal water for therapeutic purposes such as healing skin diseases as well as for relieving muscular and joint pain. plato, a greek philosopher, also believed in therapeutic benefits of hot bath and mineral waters. fig. 4. a pond of water in sani beach club, halkidiki, greece it has already been mentioned that “balaneion” created the social and architectural context for one of the earliest forms of spa in ancient greek civilization. many social gatherings centered on these public baths. subsequently, those communal bathing facilities that took place in ancient greece, are exerted a formative influence in current development of spa centers. furthermore, a pond of water combined with native plants has been placed in the courtyard of the spa center (fig. 4). it acts as a cooling zone to its own meso-space, which due to its evaporation achieves to lower the temperature of the environment. this is important especially during spring and summer periods, when the spa-center is open for the public. waterworks in this scheme achieve three goals; the first one is to enhance spa center’s aesthetic appeal. the second goal is to make a direct reference to ancient greek baths and the third one is to attempt to be a successful device of climate control. 3.7. fountain in sani beach hotel, sani, halkidiki. in 2011, the hotel managers of “sani beach hotel” were looking for a new approach for the external area of the entrance of the hotel. we thought up that an ideal solution that would work harmonically with the overall concept of the hotel would be a fountain on exceptional dimensions of 31 m long and 9 m wide with terraced levels that use recycled water (fig. 5). additionally, that would show the essential mobility of water and could be a symbol of what the visitors would expect to meet inside the hotel. at the same time an improvement of the microclimatic conditions through evaporation could be accomplished. fig. 5. a fountain in sani beach hotel, halkidiki, greece in ancient greece, cities such as athens, corinth used to develop various fountains. those constructed elements were featured as terminating points of aqueducts that brought water down from mountains in order to offer drinking water. one example could be the “enneacrounos”, a fountain built from the athenian ruler peisistratos, and contributed on providing better quality of water to local residents. therefore, it can be mentioned that from a historical perspective, fountains used to play a significant role on improving the life of a community while in contemporary greek architecture, those water features could contribute on successful and recognizable place or building making. 3.8. ponds of water and green wall in sani beach hotel, sani, halkidiki. finally, in the recently renovation of the pool bar area in “sani beach hotel”, we were influenced of the continuously growing need for sustainable tourism development and we proposed not only small ponds of water but also a green wall, that would be placed in a central point of the pool-bar area (fig. 6). in this case, there would be opportunities provided for people’s interaction and leisure while at the same time thermal comfort would be improved within the indoor area. moreover, our intention behind that project was to provide environmental friendly spaces that people could use as a meeting point and feel comfortable despite the high temperatures of summer periods. more specifically, we attempted to moderate extreme temperatures, by decreasing it approximately 50c, in order to avoid the continuous use of the mechanical cooling system. subsequently, that could contribute on energy savings as less electricity would be required. as the project has just been completed in april 2013 we cannot provide any quantitative data. however, we 55 could certainly assure the shareholders of the hotel for an expected reduction on energy consumption. fig. 6. small ponds of water and a green wall from the point of applying a green wall (fig. 7) in the specific project, we could achieve to transfer features of nature, such as green plants, in the internal environment. through that we accomplished to obtain environmental, recreational and healthy benefits for the hotel’s clients by enhancing air quality as well as by lowering temperatures inside the building during summer period. fig. 7. a green wall in sani beach hotel, halkidiki, greece according to available data that focuses on indoor air quality, it is essential for architects to choose materials which on the one hand would increase ventilation rates and on the other hand they would avoid common contaminants, such as vocs, that are harmful for people. therefore, that contaminated air should be replaced with fresher and cleaner air, where in our case that green wall containing a range of plants, could attain to that. furthermore, this green wall improves aesthetically the environment in order to satisfy the hotel shareholders, while at the same time it improves the air quality in order to satisfy the visitors. the various plants applied could absorb carbon dioxide and replace it with oxygen through the photosynthesis effect. from a psychological viewpoint, many studies have indicated that visitors would take into account the presence of green plants in the indoor environment and would consider positively the benefits acquired. subsequently, that would make them experience happiness, relaxation and a sense of desire to stay longer in this area as well as to re-visit this destination, which was our primary intention.from the viewpoint of the hotel managers that would also benefit them as on the one hand this vertical wall could provide the maximum green space with minimum use of floor space and on the other hand the specific space would be more energy efficient as less air-condition systems would be used and that would reduce their operational costs. also, they would provide more attractive and healthy living environment for their visitors as well as they would improve their environmental image. 4. conclusions as architects, we use materials and forms in every design proposed in order to communicate ideas and to create environments which encourage the interaction between people and nature. in reality, these materials and forms should highlight the significance of natural environment as well as accomplish welfare among people. as has been outlined on all the aforementioned projects, water, as a natural material with invariable identity, could be integrated properly in our architectural designs and create unique environments. in addition both hoteliers and customers could realize its significant quality and the benefits acquired through it. water improves not only aesthetically the spaces but also contributes on the environmental performance of every design. especially, it is essential to be applied when we attempt to improve the microclimatic conditions of a place. that would result to decrease temperatures and obtain thermal comfort as well as to promote communication and interaction among people because water could be featured as a meeting point. actually, our aim should always be to provide sustainable solutions and create environments that enhance the social, cultural, environmental and economic aspects of each building’s users. references albrecht benno. blue in architecture: water civilisations and climate change. 2012. available at: http://rice.iuav.it/345/1/ albrecht.pdf (assessed 15-06-2013). betsky a. 1995. take me to the water. architectural design profile, 113, 9–15. callum c. 1997. the magic & majestry of water. nexus magazine dykstra l. 2007. aqua house (thesis, masters of architecture unitec new zealand). elliott j., johns n. 1993. the influence of international tourism trends on the design of leisure resorts. international journal of contemporary hospitality management, 5 (2), 6–9. http://dx.doi.org/10.1108/09596119310036566 flesche f., burchard c. 2005. water house. prestel verlag, munich, berlin, london, new york. gómez f., pérez cueva a., valcuende m., matzarakis a. 2013. research on ecological design to enhance comfort in open spaces of acity (valencia, spain). utility of the physiological equivalent temperature (pet). ecological engineering 57, 27– 39. http://dx.doi.org/10.1016/j.ecoleng.2013.04.034 grimshaw n. british pavilion, expo 92. architectural design profile, 113, 37. grimshaw n. chiasma-helsinki museum of contemporary art. architectural design profile, 113, 45. 56 jones j. water-designing for plenty and purity. architectural design profile, 113, 17–21. mayson whalley j. 1988. water in the landscape. landscape and urban planning, 16 , 145–162. http://dx.doi.org/10.1016/0169-2046(88)90040-0 moore c. the potential for wonder. architectural design profile, 113, 23–29. nobuya nishimura, tomohiro nomura, hiroyuki iyota, shinya kimoto. 1998. novel water facilities for creation of comfortable urban micrometeorology. solar energy, 64 (4–6), 197–207. http://dx.doi.org/10.1016/s0038-092x(98)00116-9 smith a., michael pitt m. 2011. sustainable workplaces and building user comfort and satisfaction. journal of corporate real estate . 13(3), 144-156. http://dx.doi.org/10.1108/14630011111170436 wang w., tian z, ding y. 2013. investigation on the influencing factors of energy consumption andthermal comfort for a passive solar house with water thermal storage wall. energy and buildings, 64, 218–223. http://dx.doi.org/10.1016/j. enbuild.2013.05.007 world commission on environment and development (wced), our common future (new york: oxford university press, 1987), 8. received 2013 07 01 accepted after revision 2013 10 30 niki manou-andreadis – dipl architect eng – civil engineer, assistant professor in architectural design and technology at the school of architecture, faculty of engineering aristotle university of thessaloniki. main research area: sustainable architecture, technology of building skins designed with building physics criteria, energy performance of double skin facades, materials science and engineering, use of environmental friendly materials. address: 22, tritis septemvriou ave, gr-54636, thessaloniki, greece. tel.: +30 2310 240778 e-mail: nimand@nimand.gr maria milona – dipl. architect eng at school of architecture, faculty of engineering aristotle university of thessaloniki, msc in sustainable development (expected) at international hellenic university, school of economics & business administration. main research area: sustainable architecture, sustainable tourism development. address: 22, tritis septemvriou ave, gr-54636, thessaloniki, greece. tel.: +30 2310 240778 e-mail: m.milona@nimand.gr 5 journal of sustainable architecture and civil engineering 2022/2/31 *corresponding author: heidi.turunen@aalto.fi research dialogue between materials and products in architecture received 2022/02/31 accepted after revision 2022/06/01 journal of sustainable architecture and civil engineering vol. 2 / no. 31 / 2022 pp. 5-20 doi 10.5755/j01.sace.31.2.30963 research dialogue between materials and products in architecture jsace 2/31 http://dx.doi.org/10.5755/j01.sace.31.2.30963 heidi turunen aalto university, department of architecture, school of arts design and architecture, otaniementie 14, 02150 espoo, finland introduction abstract the materials life cycle consists of several phases. if application areas are targeted for architecture, comprehending the demands of the end-use phase might not be clear at the research and development phase, leading to an entity appearing fragmented. the aim of this study is to help bring order to the material research or development phases. the objective is to generate a review tool, which helps to observe different areas where architecture operates, and contemplate simultaneously the aspects during the different phases of the material development. the review tool of the material life cycle consists of tracking the raw materials until the re-used raw material, resulting in eight different stages of the material life cycle. in addition, each of the eight stages of the material life cycle is possible to observe with the five different viewpoints, which are present in architecture. these eight material life cycle stages and five aspects have been formulated as a chart. the chart consists of 40 different approaches facilitating discussion between different operators during the different phases of the material development. the chart might help set goals, frame areas, and improve comprehension of the research and development processes of the materials, especially when interdisciplinarity is involved in the research process. keywords: architecture, interdisciplinarity, materials development, materials life cycle, materials research. in architecture, construction materials have certain characteristics and aspects to fulfil depending on where and how they are applied. traditionally, practitioners have obtained an intrinsic understanding of the materials by gathering knowledge when interacting with the materials on a practical level. professionals, who are specialised in understanding the role of materials or methods in constructing, such as construction workers, craftspeople, builders, and architects, must understand the relatively simple processes involved therein. due to this basic understanding, the communication between professionals is effortless because the targets are easy to discuss; the concepts are clear; and the materials or processes are well known. though, when new technologies or materials are intended to be applied in the construction industry, special expertise is required (giesekam et. al 2016). in architecture, materials are not just thought to constitute the protective shells, carry loads, or divide spaces. the material palette utilised in architecture is in general extremely versatile. different materials must play well together leading to a meaningful and pleasant spatial experience, noting the function of the building, demands of the user, cultural aspects of the context, and overall cost of the constructing. without a holistic perspective, the outcomes might be very practical or technically competent, but they may not necessarily be easy to implement in a living environment, where various aspects are meaningful. journal of sustainable architecture and civil engineering 2022/2/31 6 due to the new demands of sustainability, which can be an enabler of cross-disciplinary co-operation, to improve the material palette for architecture, new methods for co-work may be a requirement. currently, the materials variety is much wider (ballard bell and rand 2014), and there is the possibility to design materials with the help of technology (ballard bell and rand 2006). as such, it may be wise to recognise those areas with the greatest potential for cross-disciplinary development. in architecture, the development of commercial products might involve many steps, and along the journey of the material, professionals involved in the design or construction phase might not have had a role in that process nor had an opportunity to influence the material characteristics in relation to the intended end use. in architecture, traditional methods and best practices exist, which may be considered, when developing new products for the market. in general, the designed outcomes are customised, but there is demand, due to large production units, for including repetition in the designs (gulling 2018). when processes become complicated, the knowledge and skills involved turn out to be fragmented due to specialisation (hirshinger et. al 2006). this fragmentation may be an undesirable trait in cross-disciplinary material research and development. in fragmented specialisations, the processes are led by experts from different disciplines focused on specific phases, methods, or processes, and they are not necessarily concerned with the designed outcome or entity. due to this, the fragmented knowledge at the level of materials is fused to one selected best outcome with a hierarchical evaluation by several experts during the process. as such, a wide comprehension of the entire material life cycle might be helpful to comprehend. in addition to this, it might be beneficial to understand the mindset of a person – an architect – who can influence the material selection in a building or living environment and can be educated to focus on the use-phase of the building. by combining these two aspects of the life cycle and where the architecture exists, the process and the outcome can be approached more holistically to facilitate materials research and development. consequently, the main objective of this study is to facilitate co-operation in architecturally related materials research and development. when objectives and research tasks were examined empirically from an architectural point of view, a large gap was found between the preliminary research and the commercial products. this may be due to different emphases, objectives and practices of research and development activities as well as different stages of the process. after noticing the gap, the intention arose to approach the research and development tasks with valued aspects in the final products, and to reflect the knowledge to the different stages of the material research and development process. the results of research and development tasks, if they are intended to support product development, must take into account the stage of use and the user. the architect is an expert who is aware or the requirements of both of these. materials research has several tools, but lacks a connection to architectural practices and values when the goal is to develop materials for architecture. in practice, valuable and meaningful information can be produced at the intersection of different stages in the research and development process and valued aspects in architecture. the related task has been to develop a chart-based review method generating valuable information for facilitating materials research and development. generally, material scientists or other material-related experts are exceedingly aware of the processing methods and technical aspects of materials during materials development. however, there remains some disconnect between this knowledge and its practical application in architecture. given this, the aim of the study has been to generate knowledge of aspects valued in the combination of the life cycle of materials and architecture and provide the information to those involved in the material development work. the applications of the method presented in this paper are highly practical. the method generates knowledge of the user of the building at the level of experiencing the surroundings with their senses. in addition, with the assistance of the method, it is possible to discuss the profitability of the material from the point of view of material economy, social influence, or technology. these emphasised aspects might not be clear among individuals with specific tasks at the material research stage. 7 journal of sustainable architecture and civil engineering 2022/2/31 fractured material development materials research and development cover already in themselves various disciplines. the goals can vary from developing existing materials with enhanced properties to entirely new materials. on a practical level, the research and development may concentrate on developing natural materials or artificial materials. the result of both can be materials with more refined characteristics. at its simplest, materials research and development may concentrate on only improvements to one material whilst a more advanced study can concentrate on adjusting several parameters due to a combination of different materials. for instance, smart materials or semi-smart materials have a specific functionality, property, or change in appearance (ritter 2007). currently, the design of materials can be elevated to an even more advanced level with bio-design, where materials are or have been living during the life cycle of an organism (antonelli 2014), or those materials can be adjusted by means of chemistry. similarly, materials can reach a next level in design due to metamaterials, which are engineered to achieve outcomes, which may not exist in nature. wide themes, in which a multidisciplinary approach is required, could be a replacement for plastics with bio-based alternatives, leading to sustainable construction materials, or production of super-materials with currently unidentified features. moreover, material research may apply knowledge of various disciplines to obtain pre-set targets. prior to that, the knowledge of experts, disciplines, or demands to facilitate research and development is valued and required. in the study of materials, the research phase differs substantially from the product development phase. materials research is typically conducted prior to the product design phase, especially in the cases where the end uses are not strictly defined. in the product development phase, the outcomes are defined more accurately. the frames for the development work have been documented, for instance, at the design brief, where the objectives are presented and delivered for developers, participants, or stakeholders. in the research phase, experts from the various fields might be present, and knowledge sharing of different disciplines is exceedingly valuable. in scientific research projects, the practical end-use application might not be specified precisely in the research phase. due to this, even if the potentials and properties of the material has been established to a certain level, these do not necessarily guide or determine the development process towards a certain product. this may be due to the fact that in materials research and development, scientists may study materials from specific viewpoints, such as at the level of the chemical composition. in between chemically modified materials and the end-use application of a material, there is long journey to bridge. role of materials in architecture in architectural design, both technological aspects and artistic creativity are present. architecture can be thought of as the practical fulfilment of different functions whilst, in contrast, architectural construction has a close relationship to the artistic approach (mordaunt crook 1987). in architecture, this differentiation has been considered to be significant, especially after the industrial revolution (giedion 2008). the twofold approach of technology and art can be zoomed in and observed in limited sections. the chosen materials, for instance, can be in their smaller constitutive parts observed from the standpoint of both domains. at this level, the aspects can be related, for instance, to technical features or artistic creativity in materials. various viewpoints of architecture architecture can be observed from various viewpoints. in addition to just evaluating different aspects of a material, such as material properties or artistic potentials, there are present aspects, which are meaningful in architecture on a wider perspective. the meaningful aspects can be observed from the perspective of an architectural historian (giedion 2008). the observation can focus on an architect as designer where different disciplines are present within which architecture journal of sustainable architecture and civil engineering 2022/2/31 8 operates (aalto 1978). the topic can be approached from the perspective of values, which affect the work of an architect (ukabi 2015). in addition, the focus can be directed to the framework of architectural design (eilouti 2018). above mentioned wider perspectives have been compiled in table 1. in that table, the content of each of the above mentioned perspectives have been grouped and colour coded to fit the technical, social, human, spatial experience, cultural, economic or miscellaneous sub-frames. the purpose of this list is to facilitate the comparison of different contents from broader perspectives, but also to note similarities. the most common aspects in these four broader perspectives seem to be related to the social and techno-scientific sub-frames. these are present in all of the four above mentioned broader perspectives. in addition to these, human and cultural aspects were common as well as spatially bound experiences. the economic aspects are present in all perspectives, except in the final perspective. in that case, the frame is narrower than the other perspectives, due to a focus on the design process. the reason for this might be that economic aspects can be comprehended as enablers to the design task. due to this role, these are clarified prior to the design task. table 1 different aspects which are valuable or present in architecture or architects’ work sorting or selecting materials numerous aspects influence how a material is selected to fit the design needs. these aspects have been mapped and studied recently from the standpoint of architecture (wastiels et. al 2007), (wastiels and wouters 2008). the aspects are related, for instance, to the material experience. a researcher, who works with materials, may not concentrate on the aspects, which are related to aesthetic issues or how materials feel to the touch (wilkes et. al. 2016). experiencing a material is a multisensory experience, where space and time have a role embedded with significances (fujisaki et. al 2015). at a practical level, sensory-related experiences might concern the visuality or acoustic aspects of materials. both aspects can provide spatial feedback of the surroundings for the experiencer and are valuable to recognise when selecting the materials for a built environment. aspects related to the use or maintenance of materials generate knowledge for the selection phase, when evaluating if the material is valuable to be selected. in addition, the quality of the materials in general and the profitability of the materials in terms of costs are taken into account in somehow when the architect selects the materials. the material selection and evaluation can focus on the surfaces or the other visible parts of a building. the selection process might focus on completing the specific use of a single room with suitable material choices or on a certain need for creating a specific atmosphere. in addition, the evaluation can focus on structures, which divide or create spaces. due to these aspects, in the architectural design process, various aspects must to be considered at the material level. 9 journal of sustainable architecture and civil engineering 2022/2/31 during the design phase of the construction process, the architect makes decisions when selecting unprocessed materials or commercial products composed of certain materials. the materials selection of the design phase can be based on a certain frame or criteria. this frame can be facilitated to comprehend the entity and demands of the research or development processes. recently, there has been studies on the selection method of an architect or designer (karana et. al 2008), (wastiels and wouters 2012) and on the developing tools to aid materials selection (karana et. al 2010). the decisions of architects or designers may be based on tacit knowledge, which steers the design process forward unconsciously. this tacit knowledge is formed from past experiences. when selecting materials, some decisions are based on reasoning, and those are the results of evaluation and comparison. an architect or designer can execute selections with the help of material samples provided by manufacturers. in addition to these, the selection can be based on previous well-chosen and successful selections. moreover, materials libraries act as a bridge between designers and scientists (wilkes et. al 2016). knowledge generation and sharing in the design process and constructing phase, various experts from different disciplines are often involved. the information exchanged between participants can be shared in the form of various types of documents. in that process, the drawings represent one method to share information. for knowledge sharing during the construction period of a building, meaningful information can be collected in a “building description” (rakennusselostusohje 2015) or “construction description” (rakennustapaselostus 2016). these are both made by utilising text forms. in the field of design, a more-or-less similar approach is termed the “product design specification” (rodgers and milton 2011). these documents encapsulate the project in a written format. with their help, the information of separate, but meaningful, aspects can be provided to people involved in the project, even in the early phases. these documents condense aspects, which are necessary to know even when the actual design work has not yet begun. information collection is important to facilitate and frame the design phase. materials are present in these specifications to some extent, though the focus is more on a designed object or building. at the material level, several methods to organise, comprehend, and share knowledge are common. in particular, these are valuable, when developing new products, evaluating material choices, or assessing the impacts of life cycles. the assistance can be in several forms, such as checklists during the product design phase to facilitate the discussion between engineers and designers (rousseaux et. al 2017). when evaluating the effects of materials, selections can be based on favouring green choices (spiegel and meadows 2010) or following the iso 14040 standard at life cycle assessments (lca) (iso 2006). in addition to lca, which concentrates on minimising environmental impacts, other analysis tools can be employed, such as life cycle costing (lcc), which concentrates on costs during the life cycle, and sustainable life cycle assessment (slca), which focusses on impacts related to socio-economic aspects (halog et. al 2016). in recent years, the sustainability of materials and material cycles have aroused interest among consumers (peters 2011). the aim is that waste materials, agricultural materials, or single-use materials can be taken back into the material loop (peters 2011). for industry, eco-tools are valuable to reduce environmental impacts, when developing processes and products. these can be designated into four categories: ‘inventory tools, improvement tools, prioritisation tools, and management tools’ (van berkel et al. 1997). for example, the materials, energy, and toxicity (met) matrix is one inventory tool that has been developed to analyse materials, assessing their impacts on the environment (van berkel et al. 1997). in addition, there are several eco-design tools which are purely aimed to facilitate choice evaluation within the construction industry (rousseaux et. al 2017). in addition to the abovementioned, the design phase or process can be directed to focus on a certain frame, such as ‘modular design, design for material substitution, design for disassembly (dfda), design for recycling or design for life extension (ljungberg 2007). journal of sustainable architecture and civil engineering 2022/2/31 10 this paper presents a method to facilitate multidisciplinary materials research and development from the viewpoint of architecture. the method is based on different aspects as to how architecture related material research can be framed and later observed. the outcome of the research is a flexible chart. the chart can be employed as a tool to generate valuable knowledge for the materials research phase. in addition to facilitating materials research, the chart can be used creatively as a checklist or a reminder to map various aspects, which must be taken into account when materialised outcomes in the research are related in the buildings or living environments. the chart can also be utilised to determine the boundaries to the research work in a way that the people involved in the process are able to succinctly comprehend the idea of the material. the chart can be seen a notebook or classification platform with which to generate remarks on the desired material features. another use of the chart could be to collect important information to be shared, such as the building specification utilised in architecture. in this paper, the chart has been presented with a case example. with the case example, the aim has been to disclose how the knowledge facilitating the research can be produced. as previously mentioned, the chart is generated to recognise different viewpoints, which can facilitate the mapping and collecting of valuable knowledge for research. the viewpoints are a combination of different steps of the material development phases and other diverse aspects, which are present in architecture or architectural design. depending on the focus or demands of the materials research or development task, the viewpoints can be narrowed to focus on just the essential aspects, or the chart can be utilised as a whole to gain a comprehensive overview, especially when the research scope is not yet defined. in the chart, the considerations for what is needed to be taken into account, excludes detailed technical material properties or manufacturing details. these aspects are important and can be discussed in small groups of experts during the development work. in addition, the excluded research areas, which might not get the full benefit of the chart, could include technical materials, such as the functional layers in the building envelope, or fittings, such as supplies for hvac installations. these might not necessarily possess an important role in the spatial experience from the viewpoint of architecture. in generally, the functional material layers are defined by civil engineering, and the materials are hidden inside of the wall structures. the fittings, such as supplies for hvac installations, are usually produced from standard materials. in addition, the materials or products are not in general defined by an architect. however, the chart might be beneficial, especially when mapping knowledge in architecture, when new supplies for hvac installations are developed, or there is a demand to understand detailed technical information of materials. structure of the chart the chart consists of horizontal and vertical aspects (table 2). the eight steps in the chart (marked 1 – 8) present the journey of a material from raw material to the re-use of the material. horizontally, on the top of the chart, there are placed five aspects, which are present in material development (marked a – e). those aspects are based on alvar aalto’s listing within which architecture operates (aalto 1978). the reason for selecting alvar aalto’s listing was because the definitions were comprehensive enough, but not too complex. in addition, he participated in practical design work, and contemplated the relationships between the construction of materials and structures in his writings (aalto 1978). the horizontal aspects indicate how architecture can be approached from the viewpoint, which is familiar in the culture of designing and constructing. the information discloses views on how an architect observes materials in the built environment. overall, the eight steps in the life cycle of a material, and aalto’s five-part classification generate 40 different valuable aspects as to how materials research in architecture can be observed. the objective of the chart is to facilitate research and development phase (a2, b2, c2, d2, e2), which is also present at the chart. the gathered information from other 35 viewpoints, excluding results: review method structuring valuable information for research 11 journal of sustainable architecture and civil engineering 2022/2/31 the mentioned five horizontal thematic areas of research and development phase, are fed into this phase. in addition, at the research and development phase it is possible to generate knowledge various aspects related to materials. at this point, the chart can aid in identifying boundaries and limitative aspects. vertical thematic areas the vertical thematic areas include eight steps. each of the steps presents a different phase in the life cycle of the materials. the aim of this has been to divide the life cycle of the materials into smaller parts for more specific observations. due to this, more detailed and focused knowledge can be generated to facilitate research. the vertical thematic areas during the material life cycle are: table 2 the chart presents the vertical and horizontal aspects within which architecture operates during the life cycle of the material. the research and development phase is highlighted in the table (a2, b2, c2, d2, e2) 1. raw material, 2. material research and development, 3. product, 4. commercialisation, 5. use, 6. maintenance, 7. end use, 8. re-used raw material. the first phase, raw material, consists of simple processes prior to delivering the material for sale or further developed raw material. material research and development is the phase to which the work of this paper is aimed—to facilitate research by collecting valuable information generated with the help of the chart. at this stage, the research work can be executed at universities, research institutes, or commercial companies. the research work can vary due to the objectives, research material, and research facilities of the interested parties. the knowledge generation in the research and development phase can be related to mapping research facilities, suitable tests, research methods, or the desired skills of the researchers. in the produced phase, the knowledge generation can be related to the qualities and requirements of the end use of the material before the material is launched onto the markets. in the commercialisation phase, the potential challenges and boundaries of the material are discussed when the material is developed for the market, or the material is part of a commercial product. in the use phase, the knowledge generation is related to daily life and use of the material, and in the maintenance phase, an understanding can be generated as to the serviceability of the material. at the end of the material life cycle, there are possibilities to generate knowledge of the potential end uses of the material. if the material can be utilised as a raw material again, the aspects can be pondered in the re-used raw material phase. at best, the material life cycle and knowledge generation may start again in the first phase, raw material, and the material loop is closed. journal of sustainable architecture and civil engineering 2022/2/31 12 horizontal thematic areas in the horizontal thematic areas, the materials can be classified into five different aspects for observation. this division is based to alvar aalto’s notions of the aspects which are present in architecture. the division was selected because it is general enough to fit the scheme of multidisciplinary material research, and flexible enough to include different considerations, which the constantly evolving field of architecture faces intermittently. the horizontal thematic areas include the following: a. technical aspects, b. human aspects, c. psychological aspects, d. social aspects, e. economic aspects. in this study, the technical aspects include the measured data of materials, and methods for how to process materials. in addition, these include interpretations and evaluations on a general level, such as how the material can tolerate water. this section can generate knowledge as to how the material can be modified, or what kind of technical knowledge is valuable. in addition, it is possible to consider manners, tasks, practicalities, methods, or machines. moreover, any necessary or existing technical information can be discussed in this section. valuable knowledge can be generated if the emphasis is on how the technical aspects fit the demands of research, development, or design. the desired information might be applied on a wider basis than in the regular technical data sheets or process overviews. in addition, the information may be tied to design practices. the information outside of the technical data sheets might deal with aspects, such as moisture sensitivity, weathering, wearing, and tearing of the material. aspects included in the technical thematic areas are wide and extensively present in architecture. human, psychological, social, and economic aspects are present in materials, but they might not have been studied that widely compared to the technical aspects of materials from the viewpoint of science. in human aspects, the safety of the material and its adaptation to human use can be considered. in psychological aspects, the materials can be observed from the viewpoint of material experiences. the focus here can be on how the material affects the experiencer or experienced space, noting that the experiences are personal. sensing the material through touch or experiencing the space where the material is utilised might be worth considering in order to ascertain if the material is optimal for a given purpose. when thinking of the relationship between material and society, there might also be a demand to consider themes, such as how the material fits to the existing culture and traditions and how the material adapts to living environments in general. the wise use of resources could be included as the focus of the last section, economic aspects. review process material development is a long-lasting process influenced by various aspects. thus, the aim of the review method is not to create a permanent structure but an active review method, which varies depending on the different material research tasks, end-use visions, frames where the material would be used, and disciplines of the persons involved. due to this lively nature, the focussed observation areas can be narrowed very tightly, if the observed areas are desired to be specific. the observation areas can be selected according to needs, such as product from the viewpoint of psychology, use of the material from the viewpoint of society, or maintenance of the material from the viewpoint of economy. in turn, the observation points can be selected for only a certain phase of the material life cycle, such as maintenance observed from all five horizontal thematic areas in which architecture operates. consequently, the direction of the observation can generate different knowledge. the chart can be observed from raw material towards products, where the starting platform is wider, due to delimiting knowledge. from the opposite side, the chart can be observed according to the demands of the use phase towards raw materials. in this case, the aim is to curate the right material 13 journal of sustainable architecture and civil engineering 2022/2/31 to be developed among the draft materials. the demands of use-phase visions limit and frame the material research. due to these aspects, the observation direction from the material towards products, or in the reverse order, can generate different results. the process starts by defining the preliminary research approach. in the process, all 40 aspects or selected aspects according the defined research approach are present. in the selected scope, the framing can be limited, such as a. technical aspects and 3. product, which generates a narrower view to understand these valuable aspects. the knowledge here is generated with the help of questioning. the nature of the question – answer – question method is mostly achieved through debate, where the aim is to encourage knowledge to emerge. the reason for this method is that most of the information regarding the scientific research might be clear for the professionals in specific areas but opaque to all other participants. the knowledge might not be visible at all, or the knowledge exists as tacit knowledge. due to nature of tacit knowledge, it can be difficult to share with others. with the help of the systematic method presented in the article, the knowledge has a better possibility of being revealed and shared. after answers have been generated, the final focus on the narrow topic may reveal a more accurate comprehension. after that, the generated information can be fed into the research and development process of the material. this final phase provides advice on how to proceed further. (see table 3). table 3 process for utilising the chart journal of sustainable architecture and civil engineering 2022/2/31 14 increasing knowledge with questions in the review process, the research data is collected in the requisite frames, or all 40 aspects, with the help of question generation. the objective is to return the strictly limited and framed knowledge back to the materials research to facilitate discussion. in addition, the aim is to generate research objectives more comprehensively. the first question round is generated to survey and study the material whilst further questions, if needed, can generate more specific knowledge. if the chosen method of observation in the first step (see table 3) is chosen to be very narrow, as the material produced is observed at the intersection of psychology (c. psychology 3. product, see table 2), the questions can be related to the experiences, which the material awakens, when experiencing the material as a spatial experience in the proposed physical space. on a practical level, the outcomes of the questions can be notions that the material muffles or reflects sounds; both of these affect the acoustic experience. when developing answers for the questions generated for the second round, the outcomes may be that the acoustic properties might need some improvements during the research phase. as a result of the process, more specific knowledge can be generated to serve the material development. on a practical level, the observation could concentrate on how to adjust or improve the acoustic properties when additives are planned to be mixed into the material. evaluation: testing review method the review method has been tested in practice by evaluating an early phase material research studies. in this practical test, the perspective where the questions have been approached involves the research material cellulose. the preliminary objective of the cellulose research includes knowledge generation of the potentials of this abundant material for new research openings. among several material cases, foam material was selected to reveal the method presented in this paper (fig. 1). the sketch material reveals how the method can be utilised if evaluating the potentials of early stage materials research. the selected foam material has been developed during design driven value chains in the world of cellulose, dwoc 2.0 research project, 2015 – 2018. cellulose is a material which appears as a structural material in plants or tree trunks. the cellulosic materials are derived from renewable resources and are inherently biodegradable. the raw material of this case study is wood-based cellulose. in architecture, cellulose as a material in products has been utilised in insulation materials or building papers. the review method has been preliminarily tested with one dwoc 2.0 material research case. the results of three other dwoc 2.0 cases were presented in a short conference paper at the proceedings of the nordic wood biorefinery conference (turunen 2018). in the conference paper of the conference proceedings, the cases have been observed in either a bottom-up approach from materials towards products or vice versa in a top-down approach. in this study, the life cycle of the material is widened to cover raw materials and re-used raw materials. the case study of foam material was observed from one vertical aspect a. technical aspects, but in all the life cycle stages of the material from 1. raw material to 8. re-used raw material. the purpose of the evaluated case study presented in this article is to reveal general information to assist the architect in the early stages of the material development. due to this, the views on how questions are created have been based on the approach and mind set of architects. if the observer would represent another field, the questions and information collected would have a different emphasis. in both observation tasks, however, the results of the inquiry are tied to architecture and facilitate research and development of architecture-related materials, regardless of the evaluator’s background. the reason for this is that the framing directs the process to stay within the boundaries of the architecture. research material case in this article, the method is evaluated with a material sample, where cellulose was foamed and then compressed into stiff boards. the foamed material may be utilised as a structural material. in 15 journal of sustainable architecture and civil engineering 2022/2/31 this study, the material has been modified by patterning the material, printing on the material, and shaping the material with a commercial water jet cutter. the material samples were early phase sketch materials, anticipating future research in the field of architecture. with the assistance of the review method, the material cases were studied, which in turn generated a deeper knowledge. fig. 1 foamed material on the right: patterned foam, printed foam, water jet-cut foam, and foam utilised as a structural material. photos eeva suorlahti phase is aimed at collecting information on how the research can proceed further. this means gathering information on what kinds of knowledge, tests, or processes might be beneficial to serve the research. in the fourth phase, more knowledge was generated utilising more specific questions, notions, and comments. the second round of questions is not necessary if the first phase managed to generate enough information regarding the material. in the case of foam material, the second question round can be related to map specific technical methods how to obtain information, such as defining next steps when measuring air permeability. foamed material, 2017-2018 team: heidi turunen aalto, jani lehmonen vtt soft cellulose foam has been pressed to make stiff boards. the density of the boards is adjustable. the bending stiffness of the material has been tested to be 2.95 ± 0.43 mpa, which turned out to be better than commercial peeled plaster board. the bending stiffness of the plaster board was 1.13 ± 0.13 mpa. in addition, when comparing the maximum deflection of foamed material to peeled plaster board, the measure of the foamed material was 14.45 ± 0.38 mm, and plaster board just 0.5 ± 0.1 mm. the foamed material boards can be post-processed in various ways. in this research, patterns have been pressed on the foam. a commercial printer has been tested to print thin lines. the aim of the printing was generating knowledge how ink spreads on top of the board. the printing quality was superior. in addition, the material was tested on water jet cutter. the quality of the cutting edge was sharp, and material did not absorb water. a 1:1 scale sample was made to present an early phase sketch, if the foamed material could be considered to replace gypsum boards. future application areas for foamed materials could be in indoors, where stiff boards are required in vertical or horizontal applications, and where it is desirable for the material to be recyclable, reusable and bio-based. review process in the chart, all 40 aspects were tested to fit cellulosic research. in this preliminary study, the foamed material was observed from raw material towards products, meaning that the end use of the material was not defined. due to this, the scope of the future application areas was wider than if reviewed the other way round. the results presented in this paper were limited to cover a. technical aspects from the horizontal thematic area, and 1. raw material to 8. re-used raw material. results of testing the knowledge is possible to assort with help of the assistance of 40 different viewpoints. the chart follows four phase paths (table 3). in the case of the foam material, only selected aspects are shown, the journey of the material from a technical point of view. in this article, the first round of questions is presented using simplified concepts marked in the table (table 4). an example of a simplified concept is; available technical information (a3) and the question; what are the available technical information of the foamed material (see also table 3). after that, in the third phase, the answers are created according to the questions. the answers were, for example, the high air permeability of the material. the fourth and final phase is aimed at collecting information on how the research can proceed further. this means gathering information on what kinds of knowledge, tests, or processes might be beneficial to serve the research. in the fourth phase, journal of sustainable architecture and civil engineering 2022/2/31 16 more knowledge was generated utilising more specific questions, notions, and comments. the second round of questions is not necessary if the first phase managed to generate enough information regarding the material. in the case of foam material, the second question round can be related to map specific technical methods how to obtain information, such as defining next steps when measuring air permeability. in the case of the foam material, the first round answers have been analysed, and the condensed information has been summarised below briefly in written form to provide an impression of the type of gathered information. foamed material a. technical aspects: 1. raw material to 8. re-used raw material technical aspects: when evaluating the foamed material with the help of the chart, it is worth noting that the production processes of the raw material (a1) can be relatively simple and well known, but the limitative aspects need to be mapped from the viewpoint of architecture. these can include aspects, such as the quality of the product as well as amounts of the potential production volumes. these considerations as to whether the material is wise to use from the standpoint of material properties are important to recognise at an early phase. for example, there is a notion in foam material that cellulose tends to get wet easily. on a practical level, the foamed material in this case has been analysed from the viewpoint of processing possibilities. these processes were water jet cutting, printing, pressing patterns, and constructing three-dimensional structures. when analysing the cases with the help of the chart, it was clear that more testing of the processing of the material is required. in addition, identifying the limitations and studying, for instance, the customisation potentials of the material would be beneficial to comprehend the potential end uses. in the product phase (a3), it is possible to identify the technical properties of the material. in the foam material case, these can include water tolerance, fire resistance, uv-resistance, surface sensitivity, chemical resistance, and the potential external dimensions of the material. table 4 in the chart, it is possible to select certain aspects or utilise the whole chart for knowledge generation 17 journal of sustainable architecture and civil engineering 2022/2/31 in this phase, it is possible to generate preliminary information of the tests, which are required to ascertain the potentials of the material on a technical level. in addition, it might be valuable at this phase to consider how the variations of the customisation possibilities might serve various end-products. when materials are aimed at commercialisation, various aspects must be clarified prior to that. information for that phase can be generated with the help of the frame commercialization (a4). the mapped data can increase the reliability of the material, when evaluating suitable end uses. in the case of the foam materials, the potential information for the technical datasheets or design principles may help guide the research and development phase to comprehend the material potentials. in the use phase (a5), information of a certain scenario can be generated as to how the material is expected to be utilised, allowing researchers to feed the resulting information into the research phase. the scenarios regarding how to use the foam material may lead researchers to consider aspects, such as the potential accumulation of dirt and dust on top of the relatively soft and fibrous material. in this phase, it might be wise to consider if unwanted additives or chemicals may be released during the use of the material. the gathered information can be fed into the research and development phase, where improvements and testing can be performed in anticipation of these concerns. feedback from the maintenance phase (a6) to the research and development phase would include knowledge generation of cleaning possibilities and the limitations, which the material sets for the maintenance customs. in the case of foamed material, cleaning with a wet cloth is not practical and requires consideration in the research and development phase if cleaning is desired in the maintenance phase. similarly, replacing broken or worn material can be considered in this phase. the consideration here is related to the repair methods or the possibilities for affixing a replacement. in the end use phase (a7), the consistency of the material can be considered from the viewpoint of potential re-use, and this information can be fed into the research and development phase. the aspects considered in the case of foamed material may be concentrated on noting the potential additives or chemicals planned for inclusion in the material. additives or chemicals might prevent or complicate re-use or recycling of the material. this is due to the fact that separating the ingredients in the material may be difficult, if materials are merged together, for example chemically. in addition, additives or chemicals may disrupt the biodegradability. in the early phase of the material development, the notion that the foamed material may be recycled among newspaper waste was considered from the viewpoint of additives. the last observed phase, re-used raw material (a8) generates knowledge as to where and how the material can be re-used, and what must be considered when returning the material back into the material loop. in the case of the foamed material, re-use among composites might be a valuable aspect to consider. discussion different material research and development cases can vary significantly due to the researched materials, processing methods, facilities, end applications, and customs in the materials research and development phase. however, tools have been developed to steer the process in the desired direction. the tools are often related to understanding and analysing material impacts from the viewpoint of environmental issues and sustainability. in architecture, the design processes tend to be complex due to unique outcome of the buildings in a living environment and the different demands of the users. in addition, the aspects are bound to cultures and practices. the nature of the designed outcomes is often one-off or even experimental. in human-related aspects, the interpretation is dependent on a designer, user, or experiencer. contemplating the previously mentioned aspects, gathering precise information might not be a clear process to filter the information back to the phases of materials research and development. thus, the objective of this paper is to generate a tool to facilitate materials research and development. the tool is observed from the viewpoint of architecture, but it is not designed to make the role of an architect unnecessary. understanding the aspects included in architectural design is a journal of sustainable architecture and civil engineering 2022/2/31 18 long learning process, where architects reflect their personal history, experiences, and learnings from previous design tasks. due to this, it cannot be assumed that all valuable information could be filtered to serve materials research and development solely with the help of this review method. instead, the focus is to open the mindset of the participants to versatile approaches, where architecture and materials can merge, and to facilitate effortless interactions with the participants of the research. otherwise, the use of the chart might be a superficial shortcut, lacking in depth. the primary assumption of the chart is that the materials would come back into use in a loop. this can be taken into account in the material design phase. while the materials involved in architecture might not return to serve only architectural applications later on, they can be utilised in other product fields as a new raw materials. due to this, it might be wise to survey other potential re-use possibilities at an early stage of the material research and development, not just those which are related to architecture or the construction industry. in recent years, material selection has broadened in architecture, resulting in the inclusion of various disciplines in the research and development process. given these developments, this paper focusses on a tool for recognising aspects, which might be beneficial when researching and developing materials for use in architecture. the focus of the study has been aimed especially at projects in which various disciplines are included. in terms of the role of the architect, the focus has been on which aspects an architect emphasis when performing a design task or when defining materials or products for use. the result is a systematic tool for knowledge generation to facilitate discussion during materials research and development. the principles of the tool mirror the aspects, which architects focus on and favour when evaluating suitable choices during the construction process or prior to that, and it simultaneously identifies what kind of information is valuable to notice. the aim of the tool has been to return the information back into the materials research or development phase. with the help of the chart, it is possible for all to comprehend different viewpoints related to the materials life cycle. the chart consists of 40 viewpoints related to how materials research or development can be approached. these viewpoints are generated from the horizontal aspects, which are considered vital in architecture. based on alvar aalto’s notions, these horizontal aspects include the categories of technical, human, psychological, social, or economic aspects. in contrast, the vertical aspects focus on the life cycle of the materials. the vertical viewpoints are different stages of the life cycle: raw material, material research and development, product, commercialisation, use, maintenance, end use, and re-used raw material. the chart has been tested with an early stage material research project, where the case material is foamed and pressed cellulose. the practical application of the chart presented in this paper is to facilitate knowledge generation for material research and development when developing new or recycled materials for architecture. in other words, the researched material might contain great potential, but the view is narrow, or the product exists, but a suitable material is not yet available. in both cases, knowledge generation allows for a more comprehensive comprehension of the demands before the start of the research and development phase. in addition, the chart can assist researchers in comprehending aspects-related materials research and development. this utilisation is similar to how a building specification document facilitates architectural design. as well, the chart can be utilised as a flexible tool to reveal the necessities of a certain material from different viewpoints. the chart can also be employed as a checklist to survey valuable aspects to facilitate research and development. further studies related to the topic could concentrate on the 40 frames. these considerations may be related to how valuable and meaningful information can be revealed more accurately. in particular, when there is demand to adapt various end uses, properties, or qualities of materials for the practical work of research and development. conclusion 19 journal of sustainable architecture and civil engineering 2022/2/31 acknowledgements this work was supported by tekes, the finnish funding agency for technology and innovation (currently business finland), and the finnish cultural foundation: kalle ja dagmar välimaan rahasto and suomen hypoteekkiyhdistyksen rahasto. aalto a (schildt g ed.), sketches. cambridge (mass.): the mit press; 1978. p. 60-61, 97. antonelli p (foreword), myers w. bio design: nature, science, creativity. new york: thames & hudson; 2014. p. 7. ballard bell v, rand p. materials for design. london: princeton architectural press; 2006. p. 10. ballard bell v, rand p. materials for design 2. new york: princeton architectural press; 2014. p. 8. van berkel r, willems e, lafleur m. development of an industrial ecology toolbox for the introduction of industrial ecology in enterprises. journal of cleaner production, 1997; 5 (1-2): 12-13, 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(ed). material world 2. innovative materials for architecture and design. amsterdam: frame publishers, basel: birkhäuser; 2006. p 24. iso 14040:2006. environmental management life cycle assessment principles and framework. iso international organization for standardization. references karana e, hekkert p, kandachar p. material considerations in product design: a survey on crucial material aspects used by product designers. materials and design 2008; 29: 1081-1089. https://doi. org/10.1016/j.matdes.2007.06.002 karana e, hekkert p, kandachar p. a tool for meaning driven materials selection. materials and design 2010; 31: 2932. https://doi.org/10.1016/j.matdes.2009.12.021 ljungberg l y. materials selection and design for development of sustainable products. materials and design 2007; 28: 475. https://doi.org/10.1016/j. matdes.2005.09.006 mordaunt crook j. the dilemma of style, architectural ideas from the picturesque to the post-modern. london: john murray ltd.; 1987. p. 11 peters s. 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john wiley & sons, inc. 2010. turunen h. nwbc 2018: proceedings of the 8th nordic wood biorefinery conference. vtt technology 340. espoo: vtt technical research centre of finland; 2018. p. 75-78. accessed 20.3.2022. available from www.vtt.fi/inf/pdf/technology/2018/t340.pdf journal of sustainable architecture and civil engineering 2022/2/31 20 about the author this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). ukabi e. conserving the architects’ jewel in the 21st century. frontiers of architectural research 2015; 5 (1): 12. wastiels l, wouters i. architects‘ considerations while selecting materials. materials and design 2012; 34: 584-593. https://doi.org/10.1016/j.matdes.2011.05.011 wastiels l, wouters i. material considerations in architectural design: a study of the aspects identified by architects for selecting materials. undisciplined! proceedings of the design research society conference 2008, sheffield hallam university, sheffield, uk, 16-19 july 2008; 2009; 379: 1-13. accessed 20.3.2022. available from https://core.ac.uk/download/pdf/100022.pdf wastiels l, wouters i, lindekens j. material knowledge for design the architect’s vocabulary. proceedings of iasdr 07, iasdr 2007 international association of societies of design research, emerging trends in design research, hong kong, november 12-15, 2007: 2007:. 1-16. wilkes s, wongsriruksab s, howesc p, gamestera r, witcheld h, conreene m, laughlina z, miodownik m. design tools for interdisciplinary translation of material experiences. materials and design 2016; 90: 1228. https://doi.org/10.1016/j.matdes.2015.04.01 heidi turunen aalto university, department of architecture, school of arts design and architecture adress otaniementie 14, 02150 espoo, finland tel. +358 40 536 0880 e-mail: heidi.turunen@aalto.fi 27 journal of sustainable architecture and civil engineering 2020/1/26 corresponding author: boduralper@yandex.com an investigation on post-disaster housing resident satisfaction in subaşı after the marmara earthquake received 2019/07/29 accepted after revision 2020/01/17 journal of sustainable architecture and civil engineering vol. 1 / no. 26 / 2020 pp. 27-35 doi 10.5755/j01.sace.26.1.22465 an investigation on post-disaster housing resident satisfaction in subaşı after the marmara earthquake jsace 1/26 http://dx.doi.org/10.5755/j01.sace.26.1.22465 alper bodur ondokuz mayıs university, faculty of architecture, ilkadım, samsun, 55100, turkey this paper is the result of a survey that aims to learn the perceptions and evaluations of the people living in permanent residences after the marmara earthquake. in doing so, it guides the decision-makers and researchers about the features that should be in the planning stage of permanent residences and to bring out some points that they should take into account in the future. within the extent of the study, permanent houses which have been built in subaşı village, yalova, turkey have been analyzed in the meaning of post-earthquake housing applications after the marmara earthquake on 17 august 1999. in the research, the planning of the houses built in subaşı village, the overall evaluations about the design, the principles of entitlement, the planning method of the permanent houses, and the demographic features of the householders are evaluated. for this reason, a questionnaire was created to understand the thoughts of the respondents. in this sense, users’ satisfaction was examined through the survey which based on interviews with the householders. within the questionnaire, the users have answered some questions such as demographic characteristics, economic conditions, and the degree of previous house satisfaction, the physical, social, environmental features of the permanent houses, social relations, and general perceptions. in doing this, users were asked to evaluate the positive and negative aspects of the project. one of the most critical problems in the area is transportation. on the other hand, problems have also emerged in the social relations of people settled in permanent residences after a physically destructive earthquake. in general, participants have definite opinions about the houses on earthquake resilience, size, and location of residential interiors, visual privacy, and lighting. also, they have negative notions about auditory privacy, heating, transportation to the city center, relations with relatives, problemsolving with neighbors, municipal services. as a result of the research, it is observed that the permanent residential areas in subaşı could not unite with the existing city. the findings suggest that the permanent residences in the research area produced for the people who suffered from the earthquake have not been able to meet the needs of the households sufficiently. besides, looking at the results of the study from a broad perspective, it is necessary to evaluate the subject holistically so that the permanent houses do not create new problems for the despairing households. keywords: earthquake, post-disaster housing, residential satisfaction. journal of sustainable architecture and civil engineering 2020/1/26 28 turkey is one of the countries suffering from earthquakes concerning its geological and topographical features (limoncu and bayulgen, 2005). the country has had 285 medium and large quakes in which 100,000 people missed their lives, 170,000 people were wounded, and 650,000 housing has experienced severe destruction within the years 1900-2010 (pampal and ozmen, 2015; yamalı et al., 2015). the most devastating one was an earthquake which emerged on 17 august 1999 in the marmara region of turkey. the quake provoked a tremendous loss of life and assets, corrupted the social and financial structures of the country in an almost irreparable way and gained its way into one of the most devastating earthquakes of history records (oztekin and yıldırım, 2015). according to the turkish prime ministry crisis management center, the earthquake caused the death of 17.479 people and 43,953 wounded (ozmen, 2000). the centers of i̇stanbul, kocaeli, sakarya, bolu, bursa, zonguldak, eskişehir and yalova provinces influenced significantly by the quake (tas et al., 2011). the earthquake further damaged 213,843 housing blocks which are the most significant number of dwelling units demolished by an earthquake in the devastated areas in turkey (ganapati, 2013). fig. 1 shows the position of regions corrupted on 17 august marmara earthquake. introduction fig. 1 the position of regions corrupted on 17 august marmara earthquake (source: kadıoglu, 2005) 2015). the most devastating one was an earthquake which emerged on 17 august 1999 in the marmara region of turkey. the quake provoked a tremendous loss of life and assets, corrupted the social and financial structures of the country in an almost irreparable way and gained its way into one of the most devastating earthquakes of history records (oztekin and yldrm, 2015). according to the turkish prime ministry crisis management center, the earthquake caused the death of 17.479 people and 43,953 wounded (ozmen, 2000). the centers of i̇stanbul, kocaeli, sakarya, bolu, bursa, zonguldak, eskişehir and yalova provinces influenced significantly by the quake (tas et al., 2011). the earthquake further damaged 213,843 housing blocks which are the most significant number of dwelling units demolished by an earthquake in the devastated areas in turkey (ganapati, 2013). figure 1 shows the position of regions corrupted on 17 august marmara earthquake. fig. 1. the position of regions corrupted on 17 august marmara earthquake (source: kadoglu, 2005) however, many problems come into being. the people whose houses demolished or heavily damaged had some problems such as economic, social, housing etc. for instance, the government built many permanent houses in the marmara region. indeed, all over the world, the states reveal various methods to cope with the housing problem which occurs after earthquakes (tas et al., 2007). according to federal emergency management agency (1998), there are four distinct extending phases after disasters in the housing improvement method: (1) spontaneous shelter (first 72 hours), (2) emergency shelter (first 60 days), (3) temporary housing (first year and beyond) and (4) permanent housing fema, 1998). the short and long-term housing recovery is thus a crucial viewpoint of post-disaster rebuilding (freeman, 2004; mukherji, 2015). permanent housing is the last stage to afford long-term permanent housing solutions for disaster victims (fema, 1998). permanent housing, post-disaster housing, in other words, is named by united nations (1982) as housing policies and applications following a disaster for joining the urgent, temporary and permanent sheltering requirements of the survivors of the disaster (un, 1982). another definition of post-disaster housing by the disaster and emergency management authority of turkey (afad) is that it is a lawful residence built by state or particular organizations for those who experienced radical destruction from disasters (afad, 2014). permanent houses are not houses constructed in a very different way from those produced before the quake. nevertheless, one of the most significant exceptions is that post-disaster housing is built very fast and supports to respond to the regular way of living situations. as it should be in residential however, many problems come into being. the people whose houses demolished or heavily damaged had some problems such as economic, social, housing etc. for instance, the government built many permanent houses in the marmara region. indeed, all over the world, the states reveal various methods to cope with the housing problem which occurs after earthquakes (tas et al., 2007). according to federal emergency management agency (1998), there are four distinct extending phases after disasters in the housing improvement method: (1) spontaneous shelter (first 72 hours), (2) emergency shelter (first 60 days), (3) temporary housing (first year and beyond) and (4) permanent housing fema, 1998). the short and long-term housing recovery is thus a crucial viewpoint of post-disaster rebuilding (freeman, 2004; mukherji, 2015). permanent housing is the last stage to afford long-term permanent housing solutions for disaster victims (fema, 1998). permanent housing, post-disaster housing, in other words, is named by united nations (1982) as housing policies and applications following a disaster for joining the urgent, temporary and permanent sheltering requirements of the survivors of the disaster (un, 1982). another definition of post-disaster housing by the disaster and emergency management authority of turkey (afad) is that it is a lawful residence built by state or particular organizations for those who experienced radical destruction from disasters (afad, 2014). 29 journal of sustainable architecture and civil engineering 2020/1/26 permanent houses are not houses constructed in a very different way from those produced before the quake. nevertheless, one of the most significant exceptions is that post-disaster housing is built very fast and supports to respond to the regular way of living situations. as it should be in residential buildings manufactured under natural circumstances, many factors such as cultural, environmental and economic factors should be planned in post-disaster housing. permanent houses are to build for the psychologically, culturally and economically affected people whose expectations of the built environment in which they will live for an extended period as well as fitting the housing needs (tas et al., 2007). within the extent of the study, permanent houses which have been built in subaşı village, yalova, turkey have been analyzed in the meaning of post-earthquake housing applications after the marmara earthquake on 17 august 1999. furthermore, overall evaluations are made about the satisfaction of the houses before the quake, the plan and construction phases of the permanent houses, the demographic features of the participants. within the context, this article aims to guide the decision-makers and researchers about the features that should be in the planning stage of permanent residences and to bring out some points that they should take into account in the future. methodology in the study, it is aimed to learn the perceptions and evaluations of the people living in permanent residences after the marmara earthquake about their permanent residences. the field of the study is the permanent residences built in subaşı village, yalova regarding that yalova was the place where the loss of life and property was the most intense after the earthquake of august 17, 1999. the sample was randomly chosen from the dwellings. the questionnaire was created to understand the feelings of the householders. after selecting the sample and designing the questionnaire, a total of 17 face-to-face interviews were started. although the sample size seems to be relatively small, the findings provide sufficient statistical information about the overall satisfaction of the respondents. within the questionnaire, the users have answered some questions such as demographic characteristics, economic conditions, the degree of previous house satisfaction, the physical, social, environmental features of the permanent houses, social relations, and general perceptions. in doing so, users were asked to evaluate the positive and negative aspects of the project. as aforementioned, the case study area is subaşı permanent residences in yalova province which is located in the east shoreline of marmara sea. fig. 2 shows the location of subaşı permanent residences site plan. as the smallest city in turkey with a complete area of 847 km² (marka, 2010), it is influenced by the seismic moves towards the forearms of the north anatolian fault band (url-1). following the 1999 marmara quake, 2,504 people died, and 6,042 people were injured in yalova. 9.462 houses and 727 workplaces severely; 7.917 houses and 1.036 workplaces moderately; fig. 2 map of turkey showing the location of subaşı permanent residences site plan buildings manufactured under natural circumstances, many factors such as cultural, environmental and economic factors should be planned in post-disaster housing. permanent houses are to build for the psychologically, culturally and economically affected people whose expectations of the built environment in which they will live for an extended period as well as fitting the housing needs (tas et al., 2007). within the extent of the study, permanent houses which have been built in subaş village, yalova, turkey have been analyzed in the meaning of postearthquake housing applications after the marmara earthquake on 17 august 1999. furthermore, overall evaluations are made about the satisfaction of the houses before the quake, the plan and construction phases of the permanent houses, the demographic features of the participants. within the context, this article aims to guide the decision-makers and researchers about the features that should be in the planning stage of permanent residences and to bring out some points that they should take into account in the future. methodology in the study, it is aimed to learn the perceptions and evaluations of the people living in permanent residences after the marmara earthquake about their permanent residences. the field of the study is the permanent residences built in subaş village, yalova regarding that yalova was the place where the loss of life and property was the most intense after the earthquake of august 17, 1999. the sample was randomly chosen from the dwellings. the questionnaire was created to understand the feelings of the householders. after selecting the sample and designing the questionnaire, a total of 17 face-to-face interviews were started. although the sample size seems to be relatively small, the findings provide sufficient statistical information about the overall satisfaction of the respondents. within the questionnaire, the users have answered some questions such as demographic characteristics, economic conditions, the degree of previous house satisfaction, the physical, social, environmental features of the permanent houses, social relations, and general perceptions. in doing so, users were asked to evaluate the positive and negative aspects of the project. as aforementioned, the case study area is subaş permanent residences in yalova province which is located in the east shoreline of fig. 2. map of turkey showing the location of subaş permanent residences site plan journal of sustainable architecture and civil engineering 2020/1/26 30 12.685 houses and 1.881 workplaces were slightly damaged (ozmen, 2000). fig. 3 shows the earthquakes around yalova between the years 1900 and 2013. fig. 3 earthquakes around yalova between the years 1900 and 2013 (source: kurt ve haybat, 2014) fig. 2. map of turkey showing the location of subaş permanent residences site plan following the 1999 marmara quake, 2,504 people died, and 6,042 people were injured in yalova. 9.462 houses and 727 workplaces severely; 7.917 houses and 1.036 workplaces moderately; 12.685 houses and 1.881 workplaces were slightly damaged (ozmen, 2000). figure 3 shows the earthquakes around yalova between the years 1900 and 2013. fig. 3. earthquakes around yalova between the years 1900 and 2013 (source: kurt ve haybat, 2014) following the earthquake, the turkish administration started to tackle housing regeneration to provide units to homeowners (ganapati, 2013). subsequently, the project management unit was set up for the construction of the permanent houses supported by external sources (tas et al., 2011). after the quake, a total of 43,053 permanent houses were constructed in different provinces and districts, in 27 various settlement areas (18 of turkey’s ministry of public works and settlement, the remaining 9 of the prime ministry project implementation unit) (tas et al., 2011; erten, 2003). in subaş, yalova 3002 permanent houses were constructed to settle 12.000 people. following the earthquake, the turkish administration started to tackle housing regeneration to provide units to homeowners (ganapati, 2013). subsequently, the project management unit was set up for the construction of the permanent houses supported by external sources (tas et al., 2011). after the quake, a total of 43,053 permanent houses were constructed in different provinces and districts, in 27 various settlement areas (18 of turkey’s ministry of public works and settlement, the remaining 9 of the prime ministry project implementation unit) (tas et al., 2011; erten, 2003). in subaşı, yalova 3002 permanent houses were constructed to settle 12.000 people. fig. 4 a subaşı permanent residence (source: personal archives) fig. 4. a subaş permanent residence (source: personal archives) while six housing types were built after the marmara earthquake, only two different housing types were constructed in subaş. the former model has 12 units, and the latter has 6. a photo from subasi permanent apartments is shown in figure 4. both block prototypes are comprised of a ground floor and two floors, 95 m2 residential area, three rooms, and one living room. fig. 5. a floor plan of subaş permanent houses (source: personal archives) the contract for the projects was on 16 06 2000. the area was delivered to the constructors by the ministry of public works and settlement on 28 06 2002. hence, the dwellings, which are planned to be finished in about five months, can be completed in about nine months from the place of delivery. finally, 3002 houses were built in subasi. figure 5 shows a floor plan of the permanent residences. while six housing types were built after the marmara earthquake, only two different housing types were constructed in subaşı. the former model has 12 units, and the latter has 6. a photo from subasi permanent apartments is shown in fig. 4. both block prototypes are comprised of a ground floor and two floors, 95 m2 residential area, three rooms, and one living room. 31 journal of sustainable architecture and civil engineering 2020/1/26 survey results the contract for the projects was on 16 06 2000. the area was delivered to the constructors by the ministry of public works and settlement on 28 06 2002. hence, the dwellings, which are planned to be finished in about five months, can be completed in about nine months from the place of delivery. finally, 3002 houses were built in subasi. fig. 5 shows a floor plan of the permanent residences. fig. 5 a floor plan of subaşı permanent houses (source: personal archives) fig. 4. a subaş permanent residence (source: personal archives) while six housing types were built after the marmara earthquake, only two different housing types were constructed in subaş. the former model has 12 units, and the latter has 6. a photo from subasi permanent apartments is shown in figure 4. both block prototypes are comprised of a ground floor and two floors, 95 m2 residential area, three rooms, and one living room. fig. 5. a floor plan of subaş permanent houses (source: personal archives) the contract for the projects was on 16 06 2000. the area was delivered to the constructors by the ministry of public works and settlement on 28 06 2002. hence, the dwellings, which are planned to be finished in about five months, can be completed in about nine months from the place of delivery. finally, 3002 houses were built in subasi. figure 5 shows a floor plan of the permanent residences. in the study, the demographic characteristics of the participants, such as the number of people in the household, the average monthly income were gathered. also, thoughts about earthquake resistance, interior size, indoor locations, also needed places, redundant areas, privacy, warming, transportation, neighborhood relations, the presence of green space, missing facilities, the desired location and questions about general services were asked. at first, the participants answered questions about demographic characteristics and pre-earthquake housing. according to the results of the study, the participating families consisted of 2 (35.3%) and 4 (23.5%) people. according to the majority of respondents have earnings between 1000 tl and 1900 tl (equivalent to us$ 187.68us$ 356.59) (url-2). before the earthquake, they principally lived in the middle of altinova subprovince which is at the center of the yalova province. pre-earthquake housing was mostly (64.7 %) apartment buildings. the extent of the pre-earthquake dwellings was mainly among 100-130 m2 (41.2%) and 80-100 m2 (29.4%). 76.5% of the participants were owners of the pre-earthquake residence. the apartments were severely damaged (52.9%) or destroyed (41.2) in the quake. some of the families inhabiting in subasi permanent housing come from yalova and some from central and eastern black sea region of turkey. all participants were satisfied with the location of their previous housing. nearly all participants were satisfied with the size and the place of their previous home. when asked to the participants about earthquake resilience of their permanent residences, 94.1% of the households think that their houses are resilient. in the evaluations on the size of the interiors, the participants are satisfied with living room (88.2%), rooms (41.2%), kitchen (82.4%), bathroom (94.1%), toilets (94.1%), and balconies (58.8%). when asked about the location of permanent residences, they are satisfied with living room (%82.4), rooms (94.1%), kitchen (82.4%), bathroom (88.2%), toilets (94.1%), balconies (70.6%). the participants indicated that they need a storehouse (58.8%), and a big bathroom (5.9%). some said that there is no need for extra space (35.3%). most of the items they could bring from their old journal of sustainable architecture and civil engineering 2020/1/26 32 evaluation houses (70.6%) were appropriate to fit into permanent housing. participants often wanted to live in their previous houses (82.4%) if there were any possibility. 88.2% of the families believe that visible confidentiality was realized between residences while 70.6% of them believe that no audible isolation was provided. more than half of the participants expressed that (70.6%) are not satisfied with warming. 64.7% of them responded that they are satisfied with lighting and ventilation. nearly all respondents do not complain about fitment. half of them have got difficulties to go to the city center. 94.1% of the participants have entrance to the city or district center by minibus. more than half of the participants are going to the city center rarely, the others almost every day. mainly, most of the respondents said the neighborhood relationships are well. besides, the percentage of participants who endure their conversation with their kin and friends are low. meetings with neighbors to solve problems are very low at 5.9%. nearly half of them is satisfied with the green areas. all respondents said that there is a need for a hospital in the precinct. similarly, the participants also stated that there is a demand of shopping center (47.1%), business center (41.2%), entertainment center (52.9%), mosque (29.4%) and sports hall (52.9%) in the location. all the participants noted that the waste is not taken in time. so, they are mostly (82.4%) not satisfied with the municipality services. in general, all of the participants were satisfied with the location and size of their old houses. however, almost half of the permanent residences do not like the size of the rooms and balconies of the permanent housing. they are not satisfied with the location of the balconies. the most important reason for this is that there is no user participation in the planning phase of the project. in permanent residences, they need a separate area such as a warehouse. the point that residential structures do not have flexible designs does not allow the housing units to be converted into viable needs. houses do not hold the chance to enlarge if demanded. it is an essential problem for families who want to experience old living conditions and comfort. most of the participants could be able to fit their old belongings in their permanent residences. it can be said that this situation is caused by necessity when the losses of the people whose houses are destroyed are taken into consideration in the economic conditions after the earthquake. satisfied with visual privacy, participants experience problems with auditory privacy and the heating system of the house. the main reason for this is the permanent housing construction system. the houses were built with a tunnel formwork system for quick completion. as a result, auditory problems occurred in buildings. the state, which was under pressure to relocate the people whose houses were destroyed after the earthquake, wanted to construct the houses as soon as possible. as a result, the houses have been built more rapid and economical in construction methods, thus resulted in a compromise on quality. one of the most critical problems in permanent housing is the transportation problem. the distance of the area to the city center is an essential problem for the households who want to maintain their old habits. the distance provides a living for the households below the old living standards. in this sense, permanent residences do not provide the expected benefits. on the other hand, problems have also emerged in the social relations of people settled in permanent residences after a physically destructive earthquake. for instance, in case of a collective decision to solve the problems in the building, adequate communication with the neighbors cannot be ensured, and participation in the meeting is insufficient. there is also a decrease in the relations and communication of the participants with their relatives. besides, participants are not satisfied with the amount of green space in permanent residences, which are more rural than in the city center. the participants think that the municipality does not provide adequate services to permanent residences. however, the presence of municipal services has vital significance for improving the quality of life of people residing in permanent residences. 33 journal of sustainable architecture and civil engineering 2020/1/26 fig. 6 shows the overall satisfaction with the factors related to the survey. in general, participants have definite opinions about their new houses on earthquake resistance, size, and location of residential interiors, visual privacy, and lighting, additionally, they have negative thoughts about auditory privacy, heating, transportation to the city center, relations with relatives, problem-solving with neighbors, municipal services. these findings suggest that the permanent residences produced for the people who suffered from the earthquake have not been able to meet the needs of the households sufficiently. fig. 6 overall comparison of the factors fig. 6. overall comparison of the factors figure 6 shows the overall satisfaction with the factors related to the survey. in general, participants have definite opinions about their new houses on earthquake resistance, size, and location of residential interiors, visual privacy, and lighting, additionally, they have negative thoughts about auditory privacy, heating, transportation to the city center, relations with relatives, problem-solving with neighbors, municipal services. these findings suggest that the permanent residences produced for the people who suffered from the earthquake have not been able to meet the needs of the households sufficiently. journal of sustainable architecture and civil engineering 2020/1/26 34 acknowledgment disasters are one of the most critical issues to deal with. various rehabilitative studies are carried out for families affected by disasters to return to normal living conditions. central and local governments have initiated many activities to prevent specific problems such as housing related to disasters. one of the regenerative actions of the governments is to construct post-disaster housing after a catastrophic disaster. post-disaster housing is essential to vulnerable families so that all will be capable of returning to a suitable living condition as before the disaster. nevertheless, as permanent houses are built very fast, it is crucial that the living standard of permanent housing should be suitable with the prior usage of the users. in this sense, post-use evaluations of permanent housing are getting a value to understand the issue. within the scope, permanent residences in subaşı village, yalova province in turkey have been reviewed in the study. this study was aimed to determine the characteristics that contribute to user satisfaction in the selected area. in doing so, a survey was carried out in the field, and user satisfaction was tried to be revealed. after the survey, some results emerged to evaluate the permanent residences on the area. one of the most important results of the study is that the post-disaster houses in subası cannot unite with the existing city, thus reducing the quality of life of the householders. the householders have had to adapt to a different culture, even within the same city. for this reason, it is inevitable to build permanent housing areas in the process of integration with the existing city in the broader frame. more significantly, the affected householders could not have the opportunity to participate in the project during the planning and design phases. houses have not been created in a way to answer the real needs of users. it means that the needs of households have not been appropriately addressed during the planning and design of houses. accordingly, user participation in residential planning after a disaster is a crucial requirement for future housing projects. in conclusion, looking at the results of the study from a broad perspective, it can be said that any mistakes made in the planning stage of the post-disaster housing cause dilemmas in practice. in this regard, it is necessary to evaluate the subject holistically so that the permanent houses do not create new problems for the despairing households. conclusion this article is based on the presentation of an assessment on housing satisfaction in post disaster housing: yalova subasi case presented at the 5th international conference s.arch-2018. the author wishes to thank the respondents who helped him in the survey. references afad, explanatory disaster management terms dictionary, disaster and emergency management authority, ankara, turkey, 2014. erten, g, what is the place of quake housings in our design and planning culture?, mimarlık, 309, (2003), 48. fema, a housing recovery strategy for a new madrid earthquake, draft report of the housing recovery working group, a fema / federal cusec initiative, usa, 1998. freeman, p. k., allocation of post-disaster reconstruction financing to housing, building research and information, 32, (2004), 5, pp. 427-437. https://doi. org/10.1080/0961321042000221016 ganapati, n. e., measuring the processes and outcomes of post-disaster housing recovery: lessons from gölcük, turkey, nat. hazards, 65, (2013), 3, pp. 1783-1799. https://doi.org/10.1007/s11069-0120442-8 kurt, s., and haybat, h., evaluation of location selection in yalova in terms of geomorphologic features and natural risks, urban and urbanization, pp. 673-688. efe, r., onay, t.t., sharuho, i., atasoy, e. (eds.), st. kliment ohridski university press, sofia, bulgaria, isbn: 978-954-07-3772-0, 2014. limoncu, s. and bayulgen, c., türkiye’de afet sonrası yaşanan barınma sorunları, ytu faculty of arhttps://doi.org/10.1080/0961321042000221016 https://doi.org/10.1080/0961321042000221016 https://doi.org/10.1007/s11069-012-0442-8 https://doi.org/10.1007/s11069-012-0442-8 35 journal of sustainable architecture and civil engineering 2020/1/26 about the author chitecture e-journal, 1, (2005), 1, pp. 18-27. marka, yalova investment report, eastern marmara development agency, kocaeli, turkey, 2010. mukherji, a., from tenants to homeowners: housing renters after disaster in bhuj, india, housing studies, 30, (2015), 7, pp. 1135-1157. https://doi.org /10.1080/02673037.2015.1008423 ozmen, b., damages of 17 august 1999 i̇zmit gulf earthquake, turkish earthquake foundation, ankara, turkey, 2000. oztekin, k. and yıldırım, s.t., building, constructed regions and the earthquake in kocaeli, e-journal of new world sciences academy natural and applied sciences, 2, (2007), 1, pp. 22-29. pampal, s. and ozmen, b., earthquakes are natural disasters? to cope with earthquakes, efil yayınevi yayınları, ankara, turkey, 2015. tas, n., cosgun, n. and tas, m., a qualitative evaluation of the earthquake permanent housings in turkey in terms of user satisfaction-kocaeli, gundogdu permanent housing model, building and environment, 42, (2007), 9, pp. 3418-3431. https://doi. org/10.1016/j.buildenv.2006.09.002 tas, n., tas, m. and cosgun, n., permanent housing production process after 17 august 1999 marmara earthquake in turkey, international journal of strategic property management, 15, (2011), 3, pp. 312-328. https://doi.org/10.3846/1648715x.2011.617863 un, shelter after disaster: guidelines for assistance, office of the united nations disaster relief coordinator (undro), united nations, new york, usa, 1982. url-1, http://sgdd.org.tr/wp-content/uploads/ 2017/06/yalova.pdf, data retrieved 26.03.2018. url-2, http://paracevirici.com, date retrieved 07.01.2019. yamalı, m. s., akgün, y. and karaveli, a. s., an evaluation of emergency accommodation units after earthquake, the third international conference on earthquake engineering and seismology, i̇zmir, turkey, 2015, pp. alper bodur asst. prof. dr. ondokuz mayıs university, faculty of architecture main research area disaster management, post disaster housing, social housing, building sciences, fire safety. address faculty of architecture, ondokuz mayıs university, guzel sanatlar kampusu, ilkadim, 55139 samsun, turkey. tel. +903623121919 / 4768 e-mail: boduralper@yandex.com https://doi.org/10.1080/02673037.2015.1008423 https://doi.org/10.1080/02673037.2015.1008423 https://doi.org/10.1016/j.buildenv.2006.09.002 https://doi.org/10.1016/j.buildenv.2006.09.002 https://doi.org/10.3846/1648715x.2011.617863 3 darnioji architektūra ir statyba 2013. no. 1(2) journal of sustainable architecture and civil engineering issn 2029–9990 building information modeling in architectural digital design education: questions and answers gintaris cinelis1*, vytautas janilionis2 1 kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management, studentu st. 48, lt-51367 kaunas, lithuania 2 kaunas university of technology, faculty of fundamental sciences, department of applied mathematics, studentų st. 50, lt-51368 kaunas, lithuania * corresponding author: g.cinelis@ktu.lt http://dx.doi.org/10.5755/j01.sace.1.2.3281 the paper presents the results of two last year’s research in digital education computing using object-oriented building modeling methods including parametric modeling, component-based design approaching to the concept of building information modeling (bim) as a base concept of contemporary architectural digital design. this paper summarizes results of research in bim application in architectural design, attempts to determine the problems, capture the trends of object-oriented modeling in computer aided architectural design (caad) education. the results of the analysis of various aspects of bim using surveys of architecture postgraduate students and undergraduate students of the last year are discussed. the methods of statistics for analysis of data are used. the interrelations between various factors of building information modeling as a part of caad education are investigated. the results of the work could be important for the definition of the guidelines for the future of architectural digital design education. keywords: building information modeling (bim), computer-aided architectural design (caad) education, object-oriented building modeling. 1. introduction there is a lot of debate referring to the building information modeling problem that is defined by the acronym “bim”. there is not so much hesitation why and what for we need bim in general. the importance of bim for the architecture and building in the phases of formation of conception, design, construction and maintenance was discussed in the papers (garba et.al. 2004, ibrahim 2006, cinelis 2010, cinelis 2011). however, some important questions remain: why the process of the adoption and use of bim in the designing and construction practice is slow despite the fact that the appropriate software is available and the subject is taught in universities and architectural schools for rather long period? what is the relation between education background and bim progress? our assumption is that the reasons are particularly determined in the academic area. the academic experiment was made while looking for the answers to some of these questions. the paper includes the results of the research and experiment conducted purposefully for two recent years at university. it also includes the experience of teaching of the caad subject based on object-oriented building modeling which is the base of the bim. the problem was analyzed and generalized using the feedback from the postgraduate architecture students in the form of structured surveys. the results of the work could help positively influence and redefine the content and attitudes in caad subjects where bim methods are used. the problems related to object-oriented building modeling and bim in education and their adoption processes in architectural and construction practice are also discussed in some papers. in the article (warr 2012) the author analyses different components of the problem of building information modeling. he explores the aspects of information technology, the economic aspects, the problems of copyright of bim, the choice of bim applications, seamless connection with the databases and compatibility of the formats, systems interoperability that detain the process of the prevalence of bim. as a conclusion the author proposes an “open mind” approach to the problem accepting the differences of the information technology today. 4 m. a. ambrose (2007, 2009) discusses how bim alters the way composition, scale and abstraction are addressed in design studio displacing the primacy of abstract conventions with the methodology based on systems and holistic relationships thinking and explores how the academy might prepare students of architecture for a digital practice based on the virtual building model and database management. dokonal w. (2008) in his research investigates the state of digital design in small town europe and tries to give an answer of how they as teachers and architects can give recommendations on how to teach design the new generation of architects while predicting the future of bim. the paper by m. ibrahim (2006) also looks for the answers to similar questions: to understand the needs and identify the directions where the architectural education should go when “we shift the focus toward bim based cad in design schools” and “what does it mean to teach modeling versus teaching drafting”? p. russell and d. elger (2008) point out that, as the effect of the new bim paradigm, not only students become able to use particular bim software but also learn to take the leadership in building information management. this also means understanding and controlling how the building information flows, how the methodologies that are used by the consulting engineers affect the building models, and knowing what kind of logical inconsistencies can threaten the design intention. p. sanguinetti (2009) examines the interoperability issues between design and analysis in professional practice and presents the results of the case study mapping the activities of two interdisciplinary student teams in the early design phases of a bim-enabled project and proposes a curricular structure expanding professional roles. the authors of the study (wang and wei, 2012) present an architectural education system that includes the visual organization of architectural knowledge and the establishment of teaching process management system with the application named aeim (architectural education information model). the paper by s. boeykens and h. neuckermans (2008) discusses advantages and limitations of different representation types, illustrated with examples from current commercial building information modeling applications. the authors present arguments to adapt a hybrid approach, where multiple representations should form a series of interfaces to interact with a building model. 2. methods the research conducted during the last two last years was both theoretical and experimental. following methods of the work and research were used: conceptual architectural design with computational design tools, experimental parametric object-oriented architectural modeling (aec modeling), interchange of designing data, critical analysis and surveying, analysis using descriptive statistics. for the evaluating of the associations cramer’s v measure of associations and the test independence based on chi-square statistics were used in this work. the computation work was implemented with the statistics analysis software spss (norušis, 2008). it is important to realize and to define common objectives of the course that relate also to its contents: ▪ parallel using two caad software environments to explore main objects and phases (procedures) of the object-oriented building modeling while generating and editing the complete building information model; ▪ using formal and non-formal analysis methods to define important issues of digital design using bim and to track the interrelations between various factors of modeling process. bim in our opinion should be considered not as a definite software product or identified with it. bim is an approach, an ideology of the construction activity that should outlive the design because the data of bim will be used when designing is over. on the other hand a valuable complete bim requires software capable to handle appropriate problems but inevitably having both advantages and disadvantages. the idea to use two applications revit architecture and autocad architecture in one course (4 academic hours in a week) was challenging from the point of view of the time budget. what were the main issues of our course based on object-oriented building modeling? we sought to make the course rather problem-oriented than object-oriented, to prepare the students to accept and handle the situation where bim is a means of interoperability, where interdisciplinary approach to designing, construction and maintenance is feasible. the students in the course fulfilled two exercises of conceptual modeling and the final work as a bim of the building and its surroundings. appropriate topics starting from conceptual modeling were presented parallel in both software environments. important idea was to underline the evolutionary aspects of bim instead of static fixation of earlier developed paper sketches. another substantial issue was the aspect of associativity between various parts of geometric model and non-geometric documentation elements of the project that should set up from the very beginning of the design and help to control the alteration of quatitative design parameters during designing process. thus the value of information emerged during real-time feedback thanks to the extracted information for decision making in early design stages. the quality of the final design is achieved when the comparisons of the design alternatives are possible. as an illustration of the significance of the integrated information of bim implemented in one semester was the heating energy analysis of concurrent architectural design solutions (cinelis, 2011). recent years of the evolution of caad software have an evident impact to the functions of semi-automatic conversion of various objects of computer graphics and aec objects in their diverse combinations. those functions provide great possibilities for digital design when used in an expedient and creative ways. this was also one of the main points in the course. 5 3. results and discussion at the end of the last course totally 59 students expressed their opinions in the survey that included five logical parts reflecting various aspects of the problem (fig. 1). the survey process and results were in no way related to the marks of students. many of postgraduate students as the young professionals had already had some architectural working experience. the first part included three main and one additional question about their level of knowledge of information technology (it) and computers in general, knowledge and practise from various fields of computer graphics (cg), computer aided design systems and particularly autocad (cad). that was an attempt to capture the level of computing competence of the students in general in expectation to find the factors and associations with the positive or negative attitude to bim.the second part comprises of three conceptual questions evaluating the complexity / simplicity, viability in the future and positive / negative influence to architectural creativity of bim. in the third part two questions were included about the use and viability of intelligent parametric aec objects in comparison with simple two-dimensional drawings and non-parametric three-dimensional cad objects. the fourth part forms a group of four questions intended to evaluate the efficiency of the use of the aec objects and various typical aec modeling procedures. the efficiency is considered as the ability to achieve the result using less time, actions, mental efforts or the ability to make the work easier. this part is not software-dependent and evaluates the technology in general. the last fifth part was created in order to compare two software environments revit architecture and autocad architecture from the point of view of functionality and behavior of definite parametric objects. the answers of the questionnaire were measured in ordered scale (for example, “little-good-very goodexcellent”) or as the simple lists of names in nominal scale (for example, “room/space wall roof …”). considered as the ability to achieve the result using less time, actions, mental efforts or the ability to make the work easier. this part is not software-dependent and evaluates the technology in general. the last fifth part was created in order to compare two software environments revit architecture and autocad architecture from the point of view of functionality and behavior of definite parametric objects. the answers of the questionnaire were measured in ordered scale (for example, “little-good-very goodexcellent”) or as the simple lists of names in nominal scale (for example, “room/space wall roof …”). more than a half of young architects as the respondents believe they are only on the second level (“good”) in the measure scale of it knowledge (fig. 2) what does not create very good assumption for digital design computing competence and particularly for bim. we expect to achieve more promising chart that would be symmetrical in comparison with the recent one and with the score approaching to 57.6 % for the third level (“3 very good”) in the nearest future. the numbers of working fields related to computer graphics (information visualization, modeling, rendering, animation, gis) is rather equally distributed among fig. 1. the aspects of the assessment of architectural digital design competence and bim fig. 2. evaluation of it and computer knowledge fig. 1. the aspects of the assessment of architectural digital design competence and bim 6 more than a half of young architects as the respondents believe they are only on the second level (“good”) in the measure scale of it knowledge (fig. 2) what does not create very good assumption for digital design computing competence and particularly for bim. we expect to achieve more promising chart that would be symmetrical in comparison with the recent one and with the score approaching to 57.6 % for the third level (“3 very good”) in the nearest future. considered as the ability to achieve the result using less time, actions, mental efforts or the ability to make the work easier. this part is not software-dependent and evaluates the technology in general. the last fifth part was created in order to compare two software environments revit architecture and autocad architecture from the point of view of functionality and behavior of definite parametric objects. the answers of the questionnaire were measured in ordered scale (for example, “little-good-very goodexcellent”) or as the simple lists of names in nominal scale (for example, “room/space wall roof …”). more than a half of young architects as the respondents believe they are only on the second level (“good”) in the measure scale of it knowledge (fig. 2) what does not create very good assumption for digital design computing competence and particularly for bim. we expect to achieve more promising chart that would be symmetrical in comparison with the recent one and with the score approaching to 57.6 % for the third level (“3 very good”) in the nearest future. the numbers of working fields related to computer graphics (information visualization, modeling, rendering, animation, gis) is rather equally distributed among fig. 1. the aspects of the assessment of architectural digital design competence and bim fig. 2. evaluation of it and computer knowledge fig. 2. evaluation of it and computer knowledge the numbers of working fields related to computer graphics (information visualization, modeling, rendering, animation, gis) is rather equally distributed among respondents (fig. 3): approximately each one quarter of respondents (fig. 3): approximately each one quarter of them have the knowledge and experience respectively in one, two, three or four fields. this index reflects rather good activity of the students in the cg area. the knowledge and experience of cad systems different than autocad are not high (fig. 4). in our opinion, this illustrates the fact that people do not have enough motivation and feel no necessity to invest the time into the studies of alternative systems while being students. the distribution of the percentage of the answers about the complexity of parametric architectural programs in the second part of the survey is astonishing (fig. 5). this explains one of the reasons why the adoption of bim is not an explosive process. this question was intentionally provided with five classes of answers and definite detailed descriptions of them to avoid rough evaluations and misinterpretations. the majority of the respondents (83.1 %) believe that the use of the software demands the extensive efforts and time investment. only very small number (8.5 %) of them rates the programs as relatively easy to adopt and no one thinks it could be productively used immediately. on the other hand, it seems that we can be rather optimistic about the nearest future of digital architectural design if we look to the results of next two questions (fig. 6 and fig. 7). almost half of the architects are going to use bim and the other half of them will definitely use bim in the future. even the larger part (61 %) of the respondents are sure that the software is capable to support creative architectural design work and the third of them have positive attitude in this respect. however the distribution of opinions and the graphic character of the shapes of the next two charts differ from previous ones significantly when non-parametric 2d drawings and 3d objects are compared with object-oriented modeling (fig. 8 and fig. 9). the peaks of the arch of both charts are shifted to the left, which means that the architects have more skepticism to bim in this respect and in some cases it will not be used in favour of usual simple 2d or especially 3d geometry. the aim of the fourth part of the survey was to find out the most efficient and challenging types of aec objects (fig. 10) and most efficient and challenging typical procedures of generating and editing of the design solutions (fig. 11). there was no surprise that the distributions of the fig. 3. evaluation of computer graphics knowledge fig. 4. evaluation of cad knowledge fig.5. evaluation of complexity of object-oriented programs fig. 6. evaluation of viability of object-oriented modeling fig. 7. evaluation of the impact to creativity of objectoriented modeling fig. 3. evaluation of computer graphics knowledge them have the knowledge and experience respectively in one, two, three or four fields. this index reflects rather good activity of the students in the cg area. the knowledge and experience of cad systems different than autocad are not high (fig. 4). in our opinion, this illustrates the fact that people do not have enough motivation and feel no necessity to invest the time into the studies of alternative systems while being students. respondents (fig. 3): approximately each one quarter of them have the knowledge and experience respectively in one, two, three or four fields. this index reflects rather good activity of the students in the cg area. the knowledge and experience of cad systems different than autocad are not high (fig. 4). in our opinion, this illustrates the fact that people do not have enough motivation and feel no necessity to invest the time into the studies of alternative systems while being students. the distribution of the percentage of the answers about the complexity of parametric architectural programs in the second part of the survey is astonishing (fig. 5). this explains one of the reasons why the adoption of bim is not an explosive process. this question was intentionally provided with five classes of answers and definite detailed descriptions of them to avoid rough evaluations and misinterpretations. the majority of the respondents (83.1 %) believe that the use of the software demands the extensive efforts and time investment. only very small number (8.5 %) of them rates the programs as relatively easy to adopt and no one thinks it could be productively used immediately. on the other hand, it seems that we can be rather optimistic about the nearest future of digital architectural design if we look to the results of next two questions (fig. 6 and fig. 7). almost half of the architects are going to use bim and the other half of them will definitely use bim in the future. even the larger part (61 %) of the respondents are sure that the software is capable to support creative architectural design work and the third of them have positive attitude in this respect. however the distribution of opinions and the graphic character of the shapes of the next two charts differ from previous ones significantly when non-parametric 2d drawings and 3d objects are compared with object-oriented modeling (fig. 8 and fig. 9). the peaks of the arch of both charts are shifted to the left, which means that the architects have more skepticism to bim in this respect and in some cases it will not be used in favour of usual simple 2d or especially 3d geometry. the aim of the fourth part of the survey was to find out the most efficient and challenging types of aec objects (fig. 10) and most efficient and challenging typical procedures of generating and editing of the design solutions (fig. 11). there was no surprise that the distributions of the fig. 3. evaluation of computer graphics knowledge fig. 4. evaluation of cad knowledge fig.5. evaluation of complexity of object-oriented programs fig. 6. evaluation of viability of object-oriented modeling fig. 7. evaluation of the impact to creativity of objectoriented modeling fig. 4. evaluation of cad knowledge the distribution of the percentage of the answers about the complexity of parametric architectural programs in the second part of the survey is astonishing (fig. 5). this explains one of the reasons why the adoption of bim is not an explosive process. this question was intentionally provided with five classes of answers and definite detailed descriptions of them to avoid rough evaluations and misinterpretations. the majority of the respondents (83.1 %) believe that the use of the software demands the extensive efforts and time investment. only very small number (8.5 %) of them rates the programs as relatively easy to adopt and no one thinks it could be productively used immediately. on the other hand, it seems that we can be rather optimistic about the nearest future of digital architectural design if we look to the results of next two questions (fig. 6 and fig. 7). almost half of the architects are going to use bim and the other half of them will definitely use bim in the future. even the larger part (61 %) of the respondents the knowledge and experience of cad systems different than autocad are not high (fig. 4). in our opinion, this illustrates the fact that people do not have enough motivation and feel no necessity to invest the time into the studies of alternative systems while being students. the distribution of the percentage of the answers about the complexity of parametric architectural programs in the second part of the survey is astonishing (fig. 5). this explains one of the reasons why the adoption of bim is not an explosive process. this question was intentionally provided with five classes of answers and definite detailed descriptions of them to avoid rough evaluations and misinterpretations. the majority of the respondents (83.1 %) believe that the use of the software demands the extensive efforts and time investment. only very small number (8.5 %) of them rates the programs as relatively easy to adopt and no one thinks it could be productively used immediately. on the other hand, it seems that we can be rather optimistic about the nearest future of digital architectural design if we look to the results of next two questions (fig. 6 and fig. 7). almost half of the architects are going to use bim and the other half of them will definitely use bim in the future. even the larger part (61 %) of the respondents are sure that the software is capable to support creative architectural design work and the third of them have positive attitude in this respect. fig. 3. evaluation of computer graphics knowledge fig. 4. evaluation of cad knowledge fig.5. evaluation of complexity of object-oriented programs fig. 6. evaluation of viability of object-oriented modeling fig. 7. evaluation of the impact to creativity of objectoriented modeling fig. 5. evaluation of complexity of object-oriented programs 7 are sure that the software is capable to support creative architectural design work and the third of them have positive attitude in this respect. respondents (fig. 3): approximately each one quarter of them have the knowledge and experience respectively in one, two, three or four fields. this index reflects rather good activity of the students in the cg area. the knowledge and experience of cad systems different than autocad are not high (fig. 4). in our opinion, this illustrates the fact that people do not have enough motivation and feel no necessity to invest the time into the studies of alternative systems while being students. the distribution of the percentage of the answers about the complexity of parametric architectural programs in the second part of the survey is astonishing (fig. 5). this explains one of the reasons why the adoption of bim is not an explosive process. this question was intentionally provided with five classes of answers and definite detailed descriptions of them to avoid rough evaluations and misinterpretations. the majority of the respondents (83.1 %) believe that the use of the software demands the extensive efforts and time investment. only very small number (8.5 %) of them rates the programs as relatively easy to adopt and no one thinks it could be productively used immediately. on the other hand, it seems that we can be rather optimistic about the nearest future of digital architectural design if we look to the results of next two questions (fig. 6 and fig. 7). almost half of the architects are going to use bim and the other half of them will definitely use bim in the future. even the larger part (61 %) of the respondents are sure that the software is capable to support creative architectural design work and the third of them have positive attitude in this respect. however the distribution of opinions and the graphic character of the shapes of the next two charts differ from previous ones significantly when non-parametric 2d drawings and 3d objects are compared with object-oriented modeling (fig. 8 and fig. 9). the peaks of the arch of both charts are shifted to the left, which means that the architects have more skepticism to bim in this respect and in some cases it will not be used in favour of usual simple 2d or especially 3d geometry. the aim of the fourth part of the survey was to find out the most efficient and challenging types of aec objects (fig. 10) and most efficient and challenging typical procedures of generating and editing of the design solutions (fig. 11). there was no surprise that the distributions of the fig. 3. evaluation of computer graphics knowledge fig. 4. evaluation of cad knowledge fig.5. evaluation of complexity of object-oriented programs fig. 6. evaluation of viability of object-oriented modeling fig. 7. evaluation of the impact to creativity of objectoriented modeling fig. 6. evaluation of viability of object-oriented modeling respondents (fig. 3): approximately each one quarter of them have the knowledge and experience respectively in one, two, three or four fields. this index reflects rather good activity of the students in the cg area. the knowledge and experience of cad systems different than autocad are not high (fig. 4). in our opinion, this illustrates the fact that people do not have enough motivation and feel no necessity to invest the time into the studies of alternative systems while being students. the distribution of the percentage of the answers about the complexity of parametric architectural programs in the second part of the survey is astonishing (fig. 5). this explains one of the reasons why the adoption of bim is not an explosive process. this question was intentionally provided with five classes of answers and definite detailed descriptions of them to avoid rough evaluations and misinterpretations. the majority of the respondents (83.1 %) believe that the use of the software demands the extensive efforts and time investment. only very small number (8.5 %) of them rates the programs as relatively easy to adopt and no one thinks it could be productively used immediately. on the other hand, it seems that we can be rather optimistic about the nearest future of digital architectural design if we look to the results of next two questions (fig. 6 and fig. 7). almost half of the architects are going to use bim and the other half of them will definitely use bim in the future. even the larger part (61 %) of the respondents are sure that the software is capable to support creative architectural design work and the third of them have positive attitude in this respect. however the distribution of opinions and the graphic character of the shapes of the next two charts differ from previous ones significantly when non-parametric 2d drawings and 3d objects are compared with object-oriented modeling (fig. 8 and fig. 9). the peaks of the arch of both charts are shifted to the left, which means that the architects have more skepticism to bim in this respect and in some cases it will not be used in favour of usual simple 2d or especially 3d geometry. the aim of the fourth part of the survey was to find out the most efficient and challenging types of aec objects (fig. 10) and most efficient and challenging typical procedures of generating and editing of the design solutions (fig. 11). there was no surprise that the distributions of the fig. 3. evaluation of computer graphics knowledge fig. 4. evaluation of cad knowledge fig.5. evaluation of complexity of object-oriented programs fig. 6. evaluation of viability of object-oriented modeling fig. 7. evaluation of the impact to creativity of objectoriented modeling fig. 7. evaluation of the impact to creativity of object-oriented modeling however the distribution of opinions and the graphic character of the shapes of the next two charts differ from previous ones significantly when non-parametric 2d drawings and 3d objects are compared with object-oriented modeling (fig. 8 and fig. 9). the peaks of the arch of both percentage of answers were in rather broad range: from most challenging “connections / forms between objects” procedure (almost 31 %) and most efficient “wall” (almost 20 %) object to the least problematic “floor / slab” object (5 %) and “concept” (5 %) procedure. as it was expected the charts tend to appear not strictly symmetrical in the same figure because it was allowed to designate fully freely the types and the number of the objects and procedures. significant generalization of that part were two classifications of the efficiency classes of the types of objects (table 1) and procedures (table 2) with the threshold value between 14 % and 16 %. the last part of the questionnaire was intended for the comparison of main objects and procedures of the systems revit architecture and autocad architecture (aca) and included twelve questions (table 3) with assigned four answer options (fig. 12). it is not surprising that revit hits most of the positions because it is a modern program designed for an architect trying to capture a large part of the intuitive behavior of the architectural design process. it could be only astonishing that the number of votes for revit for all questions except one is significantly bigger in comparison with aca. in our opinion it could be at least two reasons of that occurrence. firstly, the respondents are students who keep in their minds the requirements for the academic designs that are not the same as the requirements for real-life projects. secondly, informal direct talks to the people prompt the conclusion that one of the reasons of that could be a psychological factor that can be described as “better is the thing i know better”. we implemented statistical analysis to estimate relationship between answers to questions from different logical parts of questionnaire (see fig. 1). two statistically significant associations from the same two parts were found. there is a significant relationship between answers to question 3.2 “is the object-oriented modeling more promising in all cases in comparison with the simple nonparametric 3d geometric modeling?” and answers to question of priority between revit and aca 5.8 “which system has more efficient functions of the wall generating and editing?” (cramer’s v coefficient c v =0.337, p<0.05). there is also the relationship between answers to the same question 3.2 and answers to question from the same part 5.2 “which system can be pointed out as more smooth when converting the conceptual model to detailed design representation?” (cramer’s v coefficient c v =0.421, p<0.05). therefore we can predict with the probability of 0.95 that the respondents who preferred revit in questions 5.2 and 5.8 also evaluated higher parametric aec models in general. in other words the people who appreciate the functionality of parametric architectural objects tend to use the program like revit. some other relations point out the significance of general computing and digital design competence when we analyze the relations between pairs of answers to questions from the parts 1 and 2 of the questionnaire. there are the significant associations between the question 1.1 “how do you evaluate your knowledge about it and computers in general?” and the question 2.2 “are you going to use the object-oriented modeling in your activity in the future?” (spearman’s correlation coefficient r s =0.292, p<0.05). also two other correlations could be marked out: the question 1.3 “how do you evaluate your knowledge about cad?” with 2.1 “do you consider the object-oriented programs as complicated or simple ones?” (r s =0.295, p<0.05) and the question 1.3 with 2.2 (r s =0.297, p<0.05). these correlations can be interpreted that people with higher general it and cad competence tend to accept easier bim and are more motivated using it. fig. 8. object-oriented modeling versus 2d drawing fig. 9. object-oriented modeling versus non-parametric 3d models fig. 10. evaluation of aec objects types fig. 11. evaluation of generating and editing procedures of aec design solutions fig. 8. object-oriented modeling versus 2d drawing percentage of answers were in rather broad range: from most challenging “connections / forms between objects” procedure (almost 31 %) and most efficient “wall” (almost 20 %) object to the least problematic “floor / slab” object (5 %) and “concept” (5 %) procedure. as it was expected the charts tend to appear not strictly symmetrical in the same figure because it was allowed to designate fully freely the types and the number of the objects and procedures. significant generalization of that part were two classifications of the efficiency classes of the types of objects (table 1) and procedures (table 2) with the threshold value between 14 % and 16 %. the last part of the questionnaire was intended for the comparison of main objects and procedures of the systems revit architecture and autocad architecture (aca) and included twelve questions (table 3) with assigned four answer options (fig. 12). it is not surprising that revit hits most of the positions because it is a modern program designed for an architect trying to capture a large part of the intuitive behavior of the architectural design process. it could be only astonishing that the number of votes for revit for all questions except one is significantly bigger in comparison with aca. in our opinion it could be at least two reasons of that occurrence. firstly, the respondents are students who keep in their minds the requirements for the academic designs that are not the same as the requirements for real-life projects. secondly, informal direct talks to the people prompt the conclusion that one of the reasons of that could be a psychological factor that can be described as “better is the thing i know better”. we implemented statistical analysis to estimate relationship between answers to questions from different logical parts of questionnaire (see fig. 1). two statistically significant associations from the same two parts were found. there is a significant relationship between answers to question 3.2 “is the object-oriented modeling more promising in all cases in comparison with the simple nonparametric 3d geometric modeling?” and answers to question of priority between revit and aca 5.8 “which system has more efficient functions of the wall generating and editing?” (cramer’s v coefficient c v =0.337, p<0.05). there is also the relationship between answers to the same question 3.2 and answers to question from the same part 5.2 “which system can be pointed out as more smooth when converting the conceptual model to detailed design representation?” (cramer’s v coefficient c v =0.421, p<0.05). therefore we can predict with the probability of 0.95 that the respondents who preferred revit in questions 5.2 and 5.8 also evaluated higher parametric aec models in general. in other words the people who appreciate the functionality of parametric architectural objects tend to use the program like revit. some other relations point out the significance of general computing and digital design competence when we analyze the relations between pairs of answers to questions from the parts 1 and 2 of the questionnaire. there are the significant associations between the question 1.1 “how do you evaluate your knowledge about it and computers in general?” and the question 2.2 “are you going to use the object-oriented modeling in your activity in the future?” (spearman’s correlation coefficient r s =0.292, p<0.05). also two other correlations could be marked out: the question 1.3 “how do you evaluate your knowledge about cad?” with 2.1 “do you consider the object-oriented programs as complicated or simple ones?” (r s =0.295, p<0.05) and the question 1.3 with 2.2 (r s =0.297, p<0.05). these correlations can be interpreted that people with higher general it and cad competence tend to accept easier bim and are more motivated using it. fig. 8. object-oriented modeling versus 2d drawing fig. 9. object-oriented modeling versus non-parametric 3d models fig. 10. evaluation of aec objects types fig. 11. evaluation of generating and editing procedures of aec design solutions fig. 9. object-oriented modeling versus non-parametric 3d models charts are shifted to the left, which means that the architects have more skepticism to bim in this respect and in some cases it will not be used in favour of usual simple 2d or especially 3d geometry. the aim of the fourth part of the survey was to find out the most efficient and challenging types of aec objects (fig. 10) and most efficient and challenging typical procedures of generating and editing of the design solutions (fig. 11). there was no surprise that the distributions of the percentage of answers were in rather broad range: from most challenging “connections / forms between objects” procedure (almost 31 %) and most efficient “wall” (almost 20 %) object to the least problematic “floor / slab” object (5 %) and “concept” (5 %) procedure. as it was expected the charts tend to appear not strictly symmetrical in the same figure because it was allowed to designate fully freely the types and the number of the objects and procedures. percentage of answers were in rather broad range: from most challenging “connections / forms between objects” procedure (almost 31 %) and most efficient “wall” (almost 20 %) object to the least problematic “floor / slab” object (5 %) and “concept” (5 %) procedure. as it was expected the charts tend to appear not strictly symmetrical in the same figure because it was allowed to designate fully freely the types and the number of the objects and procedures. significant generalization of that part were two classifications of the efficiency classes of the types of objects (table 1) and procedures (table 2) with the threshold value between 14 % and 16 %. the last part of the questionnaire was intended for the comparison of main objects and procedures of the systems revit architecture and autocad architecture (aca) and included twelve questions (table 3) with assigned four answer options (fig. 12). it is not surprising that revit hits most of the positions because it is a modern program designed for an architect trying to capture a large part of the intuitive behavior of the architectural design process. it could be only astonishing that the number of votes for revit for all questions except one is significantly bigger in comparison with aca. in our opinion it could be at least two reasons of that occurrence. firstly, the respondents are students who keep in their minds the requirements for the academic designs that are not the same as the requirements for real-life projects. secondly, informal direct talks to the people prompt the conclusion that one of the reasons of that could be a psychological factor that can be described as “better is the thing i know better”. we implemented statistical analysis to estimate relationship between answers to questions from different logical parts of questionnaire (see fig. 1). two statistically significant associations from the same two parts were found. there is a significant relationship between answers to question 3.2 “is the object-oriented modeling more promising in all cases in comparison with the simple nonparametric 3d geometric modeling?” and answers to question of priority between revit and aca 5.8 “which system has more efficient functions of the wall generating and editing?” (cramer’s v coefficient c v =0.337, p<0.05). there is also the relationship between answers to the same question 3.2 and answers to question from the same part 5.2 “which system can be pointed out as more smooth when converting the conceptual model to detailed design representation?” (cramer’s v coefficient c v =0.421, p<0.05). therefore we can predict with the probability of 0.95 that the respondents who preferred revit in questions 5.2 and 5.8 also evaluated higher parametric aec models in general. in other words the people who appreciate the functionality of parametric architectural objects tend to use the program like revit. some other relations point out the significance of general computing and digital design competence when we analyze the relations between pairs of answers to questions from the parts 1 and 2 of the questionnaire. there are the significant associations between the question 1.1 “how do you evaluate your knowledge about it and computers in general?” and the question 2.2 “are you going to use the object-oriented modeling in your activity in the future?” (spearman’s correlation coefficient r s =0.292, p<0.05). also two other correlations could be marked out: the question 1.3 “how do you evaluate your knowledge about cad?” with 2.1 “do you consider the object-oriented programs as complicated or simple ones?” (r s =0.295, p<0.05) and the question 1.3 with 2.2 (r s =0.297, p<0.05). these correlations can be interpreted that people with higher general it and cad competence tend to accept easier bim and are more motivated using it. fig. 8. object-oriented modeling versus 2d drawing fig. 9. object-oriented modeling versus non-parametric 3d models fig. 10. evaluation of aec objects types fig. 11. evaluation of generating and editing procedures of aec design solutions fig. 10. evaluation of aec objects types percentage of answers were in rather broad range: from most challenging “connections / forms between objects” procedure (almost 31 %) and most efficient “wall” (almost 20 %) object to the least problematic “floor / slab” object (5 %) and “concept” (5 %) procedure. as it was expected the charts tend to appear not strictly symmetrical in the same figure because it was allowed to designate fully freely the types and the number of the objects and procedures. significant generalization of that part were two classifications of the efficiency classes of the types of objects (table 1) and procedures (table 2) with the threshold value between 14 % and 16 %. the last part of the questionnaire was intended for the comparison of main objects and procedures of the systems revit architecture and autocad architecture (aca) and included twelve questions (table 3) with assigned four answer options (fig. 12). it is not surprising that revit hits most of the positions because it is a modern program designed for an architect trying to capture a large part of the intuitive behavior of the architectural design process. it could be only astonishing that the number of votes for revit for all questions except one is significantly bigger in comparison with aca. in our opinion it could be at least two reasons of that occurrence. firstly, the respondents are students who keep in their minds the requirements for the academic designs that are not the same as the requirements for real-life projects. secondly, informal direct talks to the people prompt the conclusion that one of the reasons of that could be a psychological factor that can be described as “better is the thing i know better”. we implemented statistical analysis to estimate relationship between answers to questions from different logical parts of questionnaire (see fig. 1). two statistically significant associations from the same two parts were found. there is a significant relationship between answers to question 3.2 “is the object-oriented modeling more promising in all cases in comparison with the simple nonparametric 3d geometric modeling?” and answers to question of priority between revit and aca 5.8 “which system has more efficient functions of the wall generating and editing?” (cramer’s v coefficient c v =0.337, p<0.05). there is also the relationship between answers to the same question 3.2 and answers to question from the same part 5.2 “which system can be pointed out as more smooth when converting the conceptual model to detailed design representation?” (cramer’s v coefficient c v =0.421, p<0.05). therefore we can predict with the probability of 0.95 that the respondents who preferred revit in questions 5.2 and 5.8 also evaluated higher parametric aec models in general. in other words the people who appreciate the functionality of parametric architectural objects tend to use the program like revit. some other relations point out the significance of general computing and digital design competence when we analyze the relations between pairs of answers to questions from the parts 1 and 2 of the questionnaire. there are the significant associations between the question 1.1 “how do you evaluate your knowledge about it and computers in general?” and the question 2.2 “are you going to use the object-oriented modeling in your activity in the future?” (spearman’s correlation coefficient r s =0.292, p<0.05). also two other correlations could be marked out: the question 1.3 “how do you evaluate your knowledge about cad?” with 2.1 “do you consider the object-oriented programs as complicated or simple ones?” (r s =0.295, p<0.05) and the question 1.3 with 2.2 (r s =0.297, p<0.05). these correlations can be interpreted that people with higher general it and cad competence tend to accept easier bim and are more motivated using it. fig. 8. object-oriented modeling versus 2d drawing fig. 9. object-oriented modeling versus non-parametric 3d models fig. 10. evaluation of aec objects types fig. 11. evaluation of generating and editing procedures of aec design solutions fig. 11. evaluation of generating and editing procedures of aec design solutions significant generalization of that part were two classifications of the efficiency classes of the types of objects (table 1) and procedures (table 2) with the threshold value between 14 % and 16 %. the last part of the questionnaire was intended for the comparison of main objects and procedures of the systems revit architecture and autocad architecture (aca) and included twelve questions (table 3) with assigned four answer options (fig. 12). it is not surprising that revit hits most of the positions because it is a modern program designed for an architect trying to capture a large part of the intuitive behavior of the architectural design process. it could be only astonishing that the number of votes for revit for all questions except one is significantly bigger in comparison with aca. in our opinion it could be at least 8 two reasons of that occurrence. firstly, the respondents are students who keep in their minds the requirements for the academic designs that are not the same as the requirements for real-life projects. secondly, informal direct talks to the people prompt the conclusion that one of the reasons of that could be a psychological factor that can be described as “better is the thing i know better”. we implemented statistical analysis to estimate relationship between answers to questions from different logical parts of questionnaire (see fig. 1). two statistically significant associations from the same two parts were found. there is a significant relationship between answers to question 3.2 “is the object-oriented modeling more promising in all cases in comparison with the simple non-parametric 3d geometric modeling?” and answers to question of priority between revit and aca 5.8 “which system has more efficient functions of the wall generating and editing?” (cramer’s v coefficient cv = 0.337, p < 0.05). there is also the relationship between answers to the same question 3.2 and answers to question from the same part 5.2 “which system can be pointed out as more smooth when converting the conceptual model to detailed design representation?” (cramer’s v coefficient cv = 0.421, p < 0.05). therefore we can predict with the probability of 0.95 that the respondents who preferred revit in questions 5.2 and 5.8 also evaluated higher parametric aec models in general. in other words the people who appreciate the functionality of parametric architectural objects tend to use the program like revit. some other relations point out the significance of general computing and digital design competence when we analyze the relations between pairs of answers to questions from the parts 1 and 2 of the questionnaire. there are the significant associations between the question 1.1 “how do you evaluate your knowledge about it and computers in general?” and the question 2.2 “are you going to use the object-oriented modeling in your activity in the future?” (spearman’s correlation coefficient rs = 0.292, p < 0.05). also two other correlations could be marked out: the question 1.3 “how do you evaluate your knowledge about cad?” with 2.1 “do you consider the object-oriented programs as complicated or simple ones?” (rs = 0.295, p < 0.05) and the question 1.3 with 2.2 (rs = 0.297, p < 0.05). these correlations can be interpreted that people with higher general it and cad competence tend to accept easier bim and are more motivated using it. table 1. efficiency classes of the aec objects table 2. efficiency classes of the procedures 4. conclusions the results of the survey evaluating general computing literacy of the students were important to ascertain a lack of the basic expertise in information technology in the early years of studies. the same is true when speaking about knowledge of cad systems other than autocad that is used in many subjects in universities. the architectural schools have to seek for a broader and deeper it understanding what will also be a good assumption and intellectual basis for the bim and digital design computing competence in the future. after the research it is evident that the respondents took the factor of complexity of bim software very seriously and this was not influenced by any other factors because almost every respondent pointed out the same answer. this could be interpreted as one of the most significant impediments in the process of wider adoption of bim. on the other hand there are positive attitudes clearly visible when evaluating the factors of viability and the impact to creativity of bim methods. most efficient average efficient most challenging 1. 3 wall (19.7 %) 1. 6floor (10.3 %) 1. 10 terrain (22.7 %) 2. & 3. 2 – room, 9 window / door (14.1 %) 2. 4 gridlines (9.0 %) 2. 7 roof (15.1 %) 3. 1 mass (7.3 %) 3. 5 curtain wall, 8-stair (14.3 %) most efficient average efficient most challenging 1. 3 concept generating (23.0%) 1. 4 visibility and level of abstraction of objects (10.6 %) 1. 5 connections of objects (30.7 %) 2. 6 dimensioning (17.7 %) 2. 2 conversion of the concept (22.8 %) 3. 3 selection of objects (15.9 %) 3. 7 project management (15.8 %) 5.1 which system do you prefer in the point of view of 3d modeling of architectural objects? 5.2 which system can be pointed out as more smooth when converting the conceptual model to detailed design representation? 5.3 in which system the concept and techniques of associativity between different parts of design can be used more efficiently? 5.4 which program has better functionality of transferring of the models from one program to the other one? 5.5 which system in your opinion has better practical use of non-geometric data integration methods? 5.6 in which system the issues of the whole project management are solved better? 5.7 which system has more efficient functions of generating and editing of the mass objects? 5.8 which system has more efficient functions of the wall objects generating and editing? 5.9 which system has more efficient functions of the slab / floor objects generating and editing? 5.10 which system has more efficient functions of the curtain wall objects generating and editing? 5.11 which system has more efficient functions of the roof / roof slab objects generating and editing? 5.12 in which application the principle of open architecture of the system is used more successfully (the styles, the types, families; their modification / transfering between projects, program versions; the functionality of the ifc format; transferring of dimensions and fonts; application of the interface programming languages). fig. 12. comparison of the applications table 3. questions for comparison of aec objects and procedures of revit and aca fig. 12. comparison of the applications table 1. efficiency classes of the aec objects most efficient average efficient most challenging 1. 3 – wall (19.7 %) 1. 6 – floor (10.3 %) 1. 10 – terrain (22.7 %) 2. & 3. 2 – room, 9 – window / door (14.1 %) 2. 4 – gridlines (9.0 %) 2. 7 – roof (15.1 %) 3. 1 mass (7.3 %) 3. 5 – curtain wall, 8 – stair (14.3 %) table 2. efficiency classes of the procedures most efficient average efficient most challenging 1. 3 – concept generating (23.0%) 1. 4 – visibility and level of abstraction of objects (10.6 %) 1. 5 – connections of objects (30.7 %) 2. 6 – dimensioning (17.7 %) 2. 2 – conversion of the concept (22.8 %) 3. 3 – selection of objects (15.9 %) 3. 7 – project management (15.8 %) 9 4. conclusions the results of the survey evaluating general computing literacy of the students were important to ascertain a lack of the basic expertise in information technology in the early years of studies. the same is true when speaking about knowledge of cad systems other than autocad that is used in many subjects in universities. the architectural schools have to seek for a broader and deeper it understanding what will also be a good assumption and intellectual basis for the bim and digital design computing competence in the future. after the research it is evident that the respondents took the factor of complexity of bim software very seriously and this was not influenced by any other factors because almost every respondent pointed out the same answer. this could be interpreted as one of the most significant impediments in the process of wider adoption of bim. on the other hand there are positive attitudes clearly visible when evaluating the factors of viability and the impact to creativity of bim methods. the results of survey confirm the statement that mainly because of the various problems of graphical representation of the bim architectural information, the relevance of traditional both two-dimensional cad drawings and non-parametric three-dimensional models still remains. it is likely that they will be used in rather wide extent in combination with bim in the nearest future. in addition bearing in mind the versatility of the geometric language the architectural schools should keep 2d drawing and 3d modeling in their curriculum. these objects and methods still cannot be fully replaced by bim in practice. one of the essential results was the discovery of the most challenging and the most efficient aec objects and typical aec procedures using classifications based on the survey statistics. the classifications could be used both as the reference to caad teachers to let them know which bim topics should be enhanced during the course and as the recommendations to software developers in order to create more convincing caad procedures. searching for the answer to one of the most popular questions in designing practice the comparison of two architectural bim applications were fulfilled. the results indicated clear tendency among architecture students in most cases with much higher rates for revit. in some cases it could be used for reference. however in our opinion we should not extrapolate these results to the whole architectural community in general mainly because of the limited real designing experience of the students. the answers of the survey and preliminary analysis of the bim situation in designing and construction business promote new questions for the future. one of the most interesting and important questions is: how we can handle the diversity of computer aided design data that is varied by its nature to provide a fluid communication channel from the project originators and architects to constructors and maintainers? acknowledgement the authors wish to thank the architecture students who took part in the survey process. references ambrose, m. a. 2007. bim and integrated practice as provocateurs of design education, caadria 2007 [proceedings of the 12th international conference on computer aided architectural design research in asia] nanjing (china) 19-21 april 2007. ambrose, m. a. 2009. bim and comprehensive design studio education, proceedings of the 14th international conference on computer aided architectural design research in asia / yunlin (taiwan) 22-25 april 2009, pp. 757–760. boeykens s., neuckermans, h. 2008. representational limitations and improvements in building information modeling, architecture in computro [26th ecaade conference proceedings / isbn 978-0-9541183-7-2] antwerpen (belgium) 17-20 september 2008, pp. 35–42. cinelis, g., vasylius, a. 2011. the role of geometric models’ conversion as the base of digital tools of bim for sustainable architectural design. proceedings of the international conference “ecological architecture 2011”. kaunas, lithuania 13 october, p.85–92. cinelis, g. 2010. on building information modeling in early design phases: a case study of bim-based architectural competition. proceedings of the 2nd international conference “advanced construction” 11-12 november, kaunas, lithuania, technologija. p. 33–39. table 3. questions for comparison of aec objects and procedures of revit and aca 5.1 which system do you prefer in the point of view of 3d modeling of architectural objects? 5.2 which system can be pointed out as more smooth when converting the conceptual model to detailed design representation? 5.3 in which system the concept and techniques of associativity between different parts of design can be used more efficiently? 5.4 which program has better functionality of transferring of the models from one program to the other one? 5.5 which system in your opinion has better practical use of non-geometric data integration methods? 5.6 in which system the issues of the whole project management are solved better? 5.7 which system has more efficient functions of generating and editing of the mass objects? 5.8 which system has more efficient functions of the wall objects generating and editing? 5.9 which system has more efficient functions of the slab / floor objects generating and editing? 5.10 which system has more efficient functions of the curtain wall objects generating and editing? 5.11 which system has more efficient functions of the roof / roof slab objects generating and editing? 5.12 in which application the principle of open architecture of the system is used more successfully (the styles, the types, families; their modification / transfering between projects, program versions; the functionality of the ifc format; transferring of dimensions and fonts; application of the interface programming languages). 10 dokonal, w. 2008. what is the state of digital architectural design?, sigradi 2008 [proceedings of the 12th iberoamerican congress of digital graphics] la habana cuba 1-5 december 2008. garba, s. b. and mohammad a. h. 2004. a review of object oriented cad potential for building information modeling and life cycle management, edesign in architecture: ascaad’s first international conference on computer aided architectural design, 7-9 december 2004, kfupm, saudi. ibrahim, m. 2006. to bim or not to bim, this is not the question how to implement bim solutions in large design firm environments, communicating space(s) [24th ecaade conference proceedings / isbn 0-9541183-5-9] volos (greece) 6-9 september 2006, pp. 262–267. norušis m. j. 2008. ibm spss statistics 19 guide to data analysis. prentice hall, 672 p. russell p., elger, d. (2008). the meaning of bim, architecture in computro [26th ecaade conference proceedings / isbn 978-0-9541183-7-2] antwerpen (belgium) 17–20 september 2008, pp. 531-536. sanguinetti, p. 2009. bim in academia: shifting our attention from product to process, t. tidafi and t. dorta (eds) joining languages, cultures and visions: caadfutures 2009, pum, 2009, pp. 395-409. wang, y., wei z. 2012. caad education in the panorama of architectural education system: a research on visualisation of the educational tools, proceedings of the 17th international conference on computer aided architectural design research in asia / chennai 25-28 april 2012, pp. 579–588. warr d. 2012. uk bim has government impetus. available at: http://communities.bentley.com/communities/other_ communities/be_careers_network_for_academia/b/news/ archive/2012/02/14/uk-bim-has-government-impetus.aspx (accessed 14 february 2012) received 2013 01 09 accepted after revision 2013 02 26 gintaris cinelis – kaunas university of technology, assoc. prof., department of architecture and land management main research areas: computer aided architectural design (caad). address: studentų g. 48, lt-51367 kaunas. tel.: +370 37 300451 e-mail: g.cinelis@ktu.lt vytautas janilionis – kaunas university of technology, assoc. prof., department of applied mathematics. main research areas: statistical analysis of data, mathematical modeling and simulation. address: studentų st. 50, lt-51368 kaunas. tel.: +370 37 300301 e-mail: vytautas.janilionis@ktu.lt 61 darnioji architektūra ir statyba 2013. no. 2(3) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction alkaline activation is a chemical process in which a powder material of an alumosilicate nature, such as clay, is mixed with an alkaline activator to produce a paste that is able to set and harden in short time (duxson et al. 2007), (pacheco-torgal et al. 2008), (fernández-jiménez et al. 2008), (xu and van deventer 2000). the properties and characteristics (strength, shrinkage, porosity, etc.) of the resulting materials depend on nature of the raw materials and on process variables (activator, curing temperature and time, etc.). these materials, frequently termed alkaline inorganic polymers or geopolymers, constitute a new family of products which among other interesting properties can combine qualities typical of cements with those of traditional ceramics and zeolites (dimas et al. 2009). inorganic polymers possess good mechanical properties, including fire and acid resistance. mentioned properties make geopolymers as alternative construction material. it is reasonable to emphasize that the type and nature of the used starting material will directly affect the final physical and chemical properties of geopolymer (komnitsas et al. 2009). the suitability of chemically and thermally activated quaternary clays of latvia as raw material for geopolymer binders ingunda sperberga1*, andris cimmers1, maris rundans1, dainida ulme1, linda krage1, inese sidraba2 1 riga technical university, faculty of material science and applied chemistry, azenes str. 14/24, riga, lv-1048, latvia 2 university of latvia, faculty of geography and earth sciences, raina blvd. 19, riga, lv 1586, latvia *corresponding author: sperberga@ktf.rtu.lv http://dx.doi.org/10.5755/j01.sace.2.3.2848 it is now accepted that new binders are needed to replace portland cement (pc) for enhanced environmental and durability performance. the urge to reduce emissions of carbon and the fact that pc structures having built a few decades ago are already facing disintegration problems points out the handicaps of pc binders. research works carried out in developing of alkali-activated binders show that this new type of binder could have a huge potential to become as alternative building material. latvian quaternary clays were studied from the point of view of the national economy, analyzing the physical properties and chemical composition of those sediments in connection with the possibilities of their utilization in the manufacture of geopolymer materials. quaternary clay minerals dominate by illite with admixture of chlorite. quaternary clay typically is rich in fine, scattered carbonates. the aim of this study was to synthesize geopolymer product from illite clays of latvia under alkaline activation. results of the investigations showed the influence of alkalies on the transformation of clay/illite structure by curing of activated clays at different temperatures for various time. obtained results showed that illite-based clays of latvia could play a role of the raw material for production of geopolymer binders. keywords: alkaline activation, inorganic polymers, mechanical strength, quaternary clays of latvia. illite clayey deposits are one of the dominating mineral raw materials in the sedimentary cover at present area of latvia. the quaternary clays of latvia are useful for various kinds of traditional ceramic production such as bricks, building blocks, roof tiles as well as sorbents and precursors for promoting of sinterability of new ceramic products. quaternary clay deposits mostly are of glaciolacustrine origin and formed in the pleistocene glacial meltwater basins. their grain-size is various, content of clay minerals are dominated by illite (75-80 %) with admixture of kaolinite (kurss and stinkule 1997). preliminary studies (granizo et al. 2002), (yip et al. 2003), (yip et al. 2005), (dombrowski et al. 2007), (yip et al. 2008) have shown that the addition of moderate amount of calcium containing material can have a significant effect on the mechanical properties of final material. besides illite and kaolinite mentioned clays as natural additives contain carbonates such as calcite (caco3) and dolomite (camg(co3)2). the aim of this study was to synthesize geopolymer product from illite-based quaternary clays of latvia under alkaline and thermal activation. 62 2. methods in order to investigate the effect of the activator on the properties of material obtained from ap, sp and pr clays 5 and 6 m koh solutions were used. the potassium hydroxide solution was obtained by dissolving dried pellets of 99 % purity in distilled water. thus the obtained activator was added to the clay powders and mechanically mixed. afterwards cylindric samples (h = 20 mm, d = 20 mm) were made in plastic way with 25 % of average moisture content in order to obtain good paste workability. one set of prepared samples was stored in the ambient atmosphere of the laboratory. another set of prepared samples were allowed to cure at 40, 60, 80 and 100 oc temperature for 4, 3, 2 and 1 hour, accordingly and afterwards stored at an ambient atmosphere of the laboratory for testing. compressive strength of samples was tested 7, 14, 21 and 28 days after synthesis. compressive strength of samples was determined on the hardened geopolymer materials using compressive strength test set “compression test plant toninorm, toni-technic by zwick” (300 kn workload). fourier transform infrared spectroscopy was carried out on powders of activated clays (after hardening) using ftir spectrophotometer 21 prestige, shimadzu corp. in transmittance mode (interval of wave number ranging was 1300-400 cm-1). all clays and some activated materials were characterised by x-ray diffraction (model rigaku ultima+, japan, with cukα radiation at a scanning interval from 2θ = 10–60o and speed 4 o/min). the mineralogical identifications were made using an xrd pattern database (international centre for diffraction data, icdd). 3. results and discussion three quaternary clays of latvia (ap, sp and pr) with different si/al ratio used for geopolymer synthesis were characterised by means of chemical analysis (table 1). results of chemical composition show that si/al ratio varies from 2.7 (clay pr), 3.5 (clay sp) and up to 3.8 (clay ap). table 1. chemical composition of the used quaternary clays (weight %) oxides clay ap clay sp clay pr sio2 53.82 51.82 45.95 al2o3 14.32 14.69 17.07 fe2o3 5.76 5.47 6.78 tio2 0.53 0.59 0.58 cao 6.93 8.27 5.95 mgo 2.56 2.52 3.86 na2o 0.42 0.53 0.17 k2o 3.40 3.35 3.93 loi 12.26 12.76 15.71 loi: loss on ignition at 1000 °c. all clays were characterized by x-ray diffraction analysis (fig. 1). figure shows that the basic clay mineral is illite with some content of kaolinite. besides all clays contain more or less carbonates, such as calcite and dolomite, but clay pr – plagioclase as well. clays are more or less rich in quartz. fig. 1. x-ray diffractograms of the used clays: i – illite, k – kaolinite, q – quartz, c – calcite, d – dolomite, p – plagioclase compressive strength measurements are widely used as an indicator to assess the success of inorganic polymer technology. this is due to the low cost, simplicity as well as due to the fact that strength development is a primary measure of the utility of these materials in various applications (provis et al. 2005). curing took place at different temperatures for 7 up to 28 days in order to enhance structural bonding and then the hardened products were subjected to mechanical (compressive) strength testing. table 2 presents the initial compressive strength of three carbonates containing clays synthesized using an alkaline activator (5m and 6m koh solution) and cured (thermally activated) for different time at different temperatures. table 2. initial mechanical (compressive) strength of materials raw material curing temperature, °c mechanical strength, mpa after 7 day hardening after 14 day hardening 5 m koh 6 m koh 5 m koh 6 m koh clay ap 20 0 0 0 3.7 40 0 3.9 3.8 6.0 60 3.8 4.0 8.9 7.5 80 4.3 4.0 9.1 8.3 100 0 4.0 4.6 7.4 clay sp 20 0 0 3.6 4.1 40 4.0 4.8 8.9 9.5 60 7.8 7.6 11.2 8.3 80 5.8 5.3 8.7 8.3 100 4.6 4.9 7.7 9.2 clay pr 20 3.8 5.0 4.5 5.3 40 4.4 10.5 5.3 10.9 60 8.9 10.6 20.5 21.2 80 28.1 34.0 33.3 36.0 100 44.2 49.9 52.1 58.4 the general trends observed from table 2: mechanical strength of alkali activated clays are greatly dependent on (1) source material and (2) curing conditions. during the alkali attack of the alumosilicate material containing clays, an initial nucleation phase takes place where the alumosilicate species are dissolved. when the nuclei reach a critical size, they start to crystallize, but this is a very slow process so it 63 may be completed after a definite time depending on clay composition. depending on the different sio2/al2o3 ratio in the used clays (2.7 for clay pr, 3.5 for clay sp and 3.8 for clay ap) decreases the initial rate of the hardening. clay pr with smaller sio2/al2o3 ratio possesses higher initial mechanical strength in comparison with clays ap and sp. comparative results of mechanical strength of chemically and thermally activated clays after 28 day hardening are shown in figures 2 and 3. fig. 2. mechanical strength of samples activated with 5 m koh after 28 days of hardening. both figures show that strengths have increased with increasing of curing temperature only for clay pr (using for activation both 5m and 6m koh solution). clay ap showed the best values of mechanical strength cured at 60 °c temperature (using for activation 5m koh solution) and at 40 °c temperature (using 6m koh). clay sp showed higher mechanical strength activated by 5m koh solution and cured at 60 oc temperature. fig. 3. mechanical strength of samples activated with 6 m koh after 28 days of hardening. comparing results on obtained activated clays by different koh solutions, obviously not always higher concentration of koh solution facilitates the dissociation of different silicate and aluminate species, but prevents further polymerization resulting in lower compressive strength. on the other hand, with the rising of curing temperature increases mechanical strength up to definite value afterwards mechanical strength decreases because both the connectivity of silicate anions may be reduced resulting thus in poor polymerization and increases the amount of unreacted material so leading to the lowering of the strength values. it is known that the type of cation involved in the activation reaction differently affects the microstructural development of the material. the presence of alkali metal cation plays a catalytic role, controls all stages of inorganic polymer formation, in particular gel hardening and crystallization and enables an appropriate structure formation (phair and van deventer 2002), (xu and van deventer 2000). al-si mineral with higher content of na2o (plagioclase in pr clay) positively affect the geopolymerisation in koh solution. thus the best mechanical strength values have been reached using pr clay – 60 and 65 mpa depending on activator alkalinity (5m or 6m koh). factor playing an important role during activation process is the calcium content in clays. it is stated that the form of added ca2+ plays a significant role in determining the mechanical properties of the final material (yip et al. 2004). all clays contain calcite (in addition clay pr – calcium containing plagioclase) (see fig.1) being not chemically inert in the alkaline activated systems. calcite obviously is beneficial because it diminish the amount of dissolved water preventing the hydraulic attack. some authors (yip and van deventer 2003) reported that calcium increases mechanical strength after alkaline activation due to the formation of caal-si amorphous structures. it was found the development of calcium silicate hydrate and possibly coexistence with geopolymeric gel reinforcing the geopolymeric structure and as the result increasing of the mechanical strength. fig. 4 shows the xrd diffractogramms of the activated pr clay in comparison with unactivated one. xrd analysis reveals the formation of new phase (csh) – only in activated samples. furthermore it could be noticed the decrease of intensities of the present phases – kaolinite, illite and calcite. there is also registered halo peak between 2θ = 26° and 28° (marked with red semicircle) and is attributed to an amorphous silicate phase consisting of a sio4 tetrahedra sharing oxygen atoms and lacking a long-range order. halo peak for sample cured at 100 °c temperature is higher than that of sample cured at 60 °c temperature confirming the different mechanical strength values of the obtained samples. ftir analysis shows increased sensitivity for structures of short-range structural order and is considered as an appropriate technique for studying the structural evolution of amorphous alumosilicates exhibiting high heterogeneity (lee and van deventer 2002). infrared absorption bands enable identification of specific molecular components and structures. the difference in absorption frequencies among activated clays predicts transformation taking place during material synthesis. the ftir spectra of chemically and thermally activated clays are shown in fig. 5. all observed peaks were quite broad absorption bands, indicating the structural disorder in the silicate network and thus the amorphous character of the gelatinous silicate phases. the peaks at 470 cm-1 are attributed to in-plane bending of si-o and al-o linkages originating from within individual tetrahedra (van jaarsveld et al. 2002). this is a result of the presence of kaolinite some part of which remaining unreacted. 64 the peak at approximately 671 cm-1 (only for activated pr clay) represents the functional group of alo2. broad band at 802 cm-1 is attributed to the symmetric stretching of the si-o-si bonds (lee and van deventer 2003). very small peak at 879 cm-1 (only for activated pr clay) corresponds to dissolved silicate and/or alumosilicate species and indicates that dissolution of source clay have taken place (rees et al. 2007). fig. 5. ftir spectra of activated clays (all clays activated with 6 m koh and cured at 100 °c temperature): a – clay pr, b – clay sp and c – clay ap characteristic vibrations at 1033 cm-1 have been assigned to asymmetric stretching of al-o and si-o bonds originating from within individual tetrahedra. all characteristic vibrations around 1087 cm-1 are a major fingerprint of the geopolymer matrix and define the aluminium incorporation. this absorption band is attributed to asymmetric and symmetric vibrations of si-o-si and si-o-al bonding individual alo4 and sio4 tetrahedrons of geopolymers (barbosa et al. 2000). 4. conclusions illite-based geopolymer product through activating of three quaternary clays of latvia by koh solution was investigated. in this study the effect of curing temperature on the mechanical properties of different quaternary clays was investigated by measuring compressive strength over time. depending on the different sio2/al2o3 ratio in the used clays (2.7 for clay pr, 3.5 for clay sp and 3.8 for clay ap) decreases the initial rate of hardening. the best initial rate of hardening showed clay pr with smaller sio2/al2o3 ratio. it can be also concluded that with the increase of si/al ratio in the source clays appears the difference in the mechanical strength measurements with the increasing of curing temperature higher than 20 °c. curing temperature had not an essential influence on mechanical strength of activated clay ap and sp, but strength increased with increasing of curing temperature only for activated clay pr (using for activation both 5m and 6m koh solution) reaching 60 and 65 mpa, accordingly. ftir spectra and xrd results confirmed the differences among activated clays developing the diverse final strength of the obtained samples. acknowledgment the research work was carried out in the frame of erdf project „elaboration of innovative low temperature composite materials from local mineral raw materials” (no. 2010/0244/2dp/2.1.1.1.0/10/apia/viaa/152). fig. 4. x-ray diffractograms of unactivated pr clay (a) and activated ones: b – activated with 6 m koh and cured at 60 oc temperature, c – activated with 6 m koh and cured at 100 °c temperature 65 references barbosa v. f. f., mackenzie 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materials. ceramic transactions, 153, 187–209. yip c. k., lukey g. c., van deventer j. s. j. 2005. the coexistence of geopolymeric gel and calcium silicate hydrate at the early stage of alkaline activation. cement and concrete research, 35, 9, 1688–1697. http://dx.doi.org/10.1016/j.cemconres. 2004.10.042 yip c. k., van deventer j. s. j. 2003. microanalysis of calcium silicate hydrate gel formed within a geopolymeric binder. journal of materials science, 38, 3851–3860. http://dx.doi.org/10.1016/j.cemconres.2004.10.042 received 2012 11 30 accepted after revision 2013 04 22 ingunda sperberga – assoc. prof. in riga technical university, faculty of material sciences and applied chemistry, institute of silicate materials. main research area: mineral raw materials of latvia and their use for material obtaining. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 26272343 sperberga@ktf.rtu.lve-mail: 66 andris cimmers – senior researcher in riga technical university, faculty of material sciences and applied chemistry, institute of silicate materials. main research area: using of local mineral raw materials for material development. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 294 93745 e-mail: cimmers@ktf.rtu.lv maris rundans – master’s degree student in riga technical university, faculty of material sciences and applied chemistry, institute of silicate materials. main research area: using of mineral raw materials for obtaining of ceramic products. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 293 24526 e-mail: maris87@inbox.lv dainida ulme – master’s degree student in riga technical university, faculty of material sciences and applied chemistry, institute of silicate materials. main research area: using of local clays for obtaining of geopolymer materials. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 271 68237 e-mail: dainidaulme@gmail.com linda krage – assoc. prof. in riga technical university, faculty of material sciences and applied chemistry, institute of silicate materials. main research area: conservation and restoration of stone materials, development of products from local mineral raw materials. address: azenes str. 14/24, riga, lv-1048, latvia. tel.: +371 264 32537 e-mail: linda@ktf.rtu.lv inese sidraba – researcher in university of latvia, faculty of geography and earth sciences. main research area: geology of local mineral raw materials. address: raina blvd. 19, riga, lv 1586, latvia. tel.: +371 294 10589 e-mail: inese@ktf.rtu.lv 29 journal of sustainable architecture and civil engineering 2019/1/24 *corresponding author: kristina.mjornell@ri.se moisture safety of wooden buildings – design, construction and operation received 2018/12/16 accepted after revision 2019/02/05 journal of sustainable architecture and civil engineering vol. 1 / no. 24 / 2019 pp. 29-35 doi 10.5755/j01.sace.24.1.22341 moisture safety of wooden buildings – design, construction and operation jsace 1/24 http://dx.doi.org/10.5755/j01.sace.24.1.22341 kristina mjörnell* rise research institutes of sweden, eklandagatan 86, 412 66 gothenburg, sweden division of building physics, lund university, box 118, 221 00 lund, sweden lars olsson rise research institutes of sweden, eklandagatan 86, 412 66 gothenburg, sweden introduction during the last decade, building in wood has increased, mainly due to environmental awareness and targets to decrease the carbon footprint originated from the production of building materials. new technologies such as clt (cross laminated timber) have accelerated the construction of multi-story wooden buildings. the clt structure has been used both for housing and offices. due to the extensive size of the buildings and relatively fast assembly of the buildings, weather protection has not always been used. it is commonly known that building materials sensitive to moisture need to be protected against high moisture conditions and water during construction. if this is not done, there is an increased risk of microbial growth which can result in health problems for future users of the building, extensive costs for the remediation and exchange of materials, but also lack of trust in the construction industry. there are disagreements between the building industry and researchers how sensitive wooden buildings are to exposure to high moisture levels and water during storage at sites and construction. based on results from several research projects studying moisture conditions both in the laboratory and in the field, recommendations for procurement, storage and handling of wood during construction to assure moisture safety are suggested in this paper. keywords: clt, guidance, massive wooden buildings, moisture safety, mould growth. the nordic countries have a long tradition to build in wood. wood is suitable for construction of buildings since it is a common, inexpensive, durable material with a long lifetime, if not exposed to extreme conditions. during the last decades many swedish municipalities have shown increased interest in building in wood to strive towards ambitious environmental targets considering low carbon footprint housing. this has led to many national initiatives promoting wood for new urban developments, (trästad 2018) and (smart housing småland 2018). due to the increased interest for wooden buildings by the market, new technologies based on cross-laminated timber (clt) which gives a higher rigidity and strength to wooden structures have been developed, enabling the evolution of high-rise buildings. clt panels are laminated wood products and systems based on prefabricated elements made of 3-7 perpendicular oriented layers of parallel boards glued together (trästad 2018). the advantages of building with clt are journal of sustainable architecture and civil engineering 2019/1/24 30 many from a lifecycle perspective, partly because of the low environmental impact (embodied energy), prefabrication, which means efficient production which reduces construction time, but also providing a better working environment and minimizing waste. the construction and technology are imported from central europe. lately, a lot of attention has been paid to moisture issues, especially when clt buildings are erected without weather protection. the suppliers claim that weather protection is not necessary, whereas the researchers fear that exposure to rain during erection might cause damages and problems with mould growth in the future. in some cases, it is practically impossible to arrange weather protection since the width and height of the construction would require very complicated fasteners to cope with the wind loads from the tent, fig. 1-3. many buildings in sweden, both new and old, suffer from moisture-related problems causing both decreased durability and mould growth which may affect the indoor air quality with negative consequences on health. the national board of housing, building and planning in sweden carried out fig. 1 examples of moisture critical construction methods are multi-storey buildings constructed without weather protection and storing wood and insulation material wrapped in plastic sheeting at the building site fig. 2 the left building is a multi-story wooden building assembled without weather protection and the right is a multi-storey building assembled with weather protection without weather protection. the suppliers claim that weather protection is not necessary, whereas the researchers fear that exposure to rain during erection might cause damages and problems with mould growth in the future. in some cases, it is practically impossible to arrange weather protection since the width and height of the construction would require very complicated fasteners to cope with the wind loads from the tent, fig. 1-3. fig. 1a and 1b. examples of moisture critical construction methods are multi-storey buildings constructed without weather protection storing wood and insulation material wrapped in plastic sheeting at the building site. fig. 2a and 2b. the left building is a multi-story wooden building assembled without weather protection and the right is a multi-storey building assembled with weather protection. without weather protection. the suppliers claim that weather protection is not necessary, whereas the researchers fear that exposure to rain during erection might cause damages and problems with mould growth in the future. in some cases, it is practically impossible to arrange weather protection since the width and height of the construction would require very complicated fasteners to cope with the wind loads from the tent, fig. 1-3. fig. 1a and 1b. examples of moisture critical construction methods are multi-storey buildings constructed without weather protection storing wood and insulation material wrapped in plastic sheeting at the building site. fig. 2a and 2b. the left building is a multi-story wooden building assembled without weather protection and the right is a multi-storey building assembled with weather protection. a a b b without weather protection. the suppliers claim that weather protection is not necessary, whereas the researchers fear that exposure to rain during erection might cause damages and problems with mould growth in the future. in some cases, it is practically impossible to arrange weather protection since the width and height of the construction would require very complicated fasteners to cope with the wind loads from the tent, fig. 1-3. fig. 1a and 1b. examples of moisture critical construction methods are multi-storey buildings constructed without weather protection storing wood and insulation material wrapped in plastic sheeting at the building site. fig. 2a and 2b. the left building is a multi-story wooden building assembled without weather protection and the right is a multi-storey building assembled with weather protection. without weather protection. the suppliers claim that weather protection is not necessary, whereas the researchers fear that exposure to rain during erection might cause damages and problems with mould growth in the future. in some cases, it is practically impossible to arrange weather protection since the width and height of the construction would require very complicated fasteners to cope with the wind loads from the tent, fig. 1-3. fig. 1a and 1b. examples of moisture critical construction methods are multi-storey buildings constructed without weather protection storing wood and insulation material wrapped in plastic sheeting at the building site. fig. 2a and 2b. the left building is a multi-story wooden building assembled without weather protection and the right is a multi-storey building assembled with weather protection. 31 journal of sustainable architecture and civil engineering 2019/1/24 fig. 3 new office building with clt (crosslaminated timber) framework assembled without weather protection a b fig. 3a and 3b. new office building with clt (cross-laminated timber) framework assembled without weather protection. many buildings in sweden, both new and old, suffer from moisture-related problems causing both decreased durability, mould growth which may affect the indoor air quality with negative consequences on health. the national board of housing, building and planning carried out a nationwide study of buildings’ energy use, technical status and indoor environment, named the betsi study. the material is unique, as it is based on investigations of a stochastic selection of 1800 buildings (boverket 2009). the estimation was that approximately 66 per cent of all buildings in sweden had some type of damage and 45 percentage of these damages were caused by moisture which could have an impact on the indoor environment. however, most shortcomings that were registered were not of a serious nature. the cost for remedying all identified damage and meeting needs for maintenance was estimated to between 230 and 330 billion sek (approximately 23-33 billion euros), also including measures for decreasing noise levels in schools. in addition to high costs for remediation, the customers, tenants and users of the buildings lose confidence in the building industry when their buildings are exposed to moisture problems. these problems could have been avoided if moisture issues had been focused on and dealt with throughout the building process. a method for including moisture safety in the building process (byggaf) was developed ten years ago and is referred to in the swedish building regulation bbr and is quite widely used in the swedish building sector. the purpose of the method is to help all the stakeholders involved to work with moisture safety activities and to document them in a structured way. the method includes a number of routines, templates and checklists for clients to formulate requirements for moisture safety and to follow up and document the measures carried out by different participants. there are also tools for architects and design engineers, such as lists of references to literature, checklists and design examples to use for dry building design. for contractors, specific routines have been developed for moisture control during construction. the method has been applied to several building projects. based on the experience from these projects, the method and the tools have been evaluated and revised, (mjörnell et al 2012, byggaf 2018). byggaf gives guidance on a very general level and does not provide advice on choice of design of constructions and materials or how to handle wood at the construction site. thus, a specific guide for controlling moisture and mould in wooden constructions exposed to the outdoor climate is needed. a guide with recommendations, based on former research studies performed by the authors, is presented in this paper. fig. 3a and 3b. new office building with clt (cross-laminated timber) framework assembled without weather protection. many buildings in sweden, both new and old, suffer from moisture-related problems causing both decreased durability, mould growth which may affect the indoor air quality with negative consequences on health. the national board of housing, building and planning carried out a nationwide study of buildings’ energy use, technical status and indoor environment, named the betsi study. the material is unique, as it is based on investigations of a stochastic selection of 1800 buildings (boverket 2009). the estimation was that approximately 66 per cent of all buildings in sweden had some type of damage and 45 percentage of these damages were caused by moisture which could have an impact on the indoor environment. however, most shortcomings that were registered were not of a serious nature. the cost for remedying all identified damage and meeting needs for maintenance was estimated to between 230 and 330 billion sek (approximately 23-33 billion euros), also including measures for decreasing noise levels in schools. in addition to high costs for remediation, the customers, tenants and users of the buildings lose confidence in the building industry when their buildings are exposed to moisture problems. these problems could have been avoided if moisture issues had been focused on and dealt with throughout the building process. a method for including moisture safety in the building process (byggaf) was developed ten years ago and is referred to in the swedish building regulation bbr and is quite widely used in the swedish building sector. the purpose of the method is to help all the stakeholders involved to work with moisture safety activities and to document them in a structured way. the method includes a number of routines, templates and checklists for clients to formulate requirements for moisture safety and to follow up and document the measures carried out by different participants. there are also tools for architects and design engineers, such as lists of references to literature, checklists and design examples to use for dry building design. for contractors, specific routines have been developed for moisture control during construction. the method has been applied to several building projects. based on the experience from these projects, the method and the tools have been evaluated and revised, (mjörnell et al 2012, byggaf 2018). byggaf gives guidance on a very general level and does not provide advice on choice of design of constructions and materials or how to handle wood at the construction site. thus, a specific guide for controlling moisture and mould in wooden constructions exposed to the outdoor climate is needed. a guide with recommendations, based on former research studies performed by the authors, is presented in this paper. a nationwide study of buildings’ energy use, technical status and indoor environment, named the betsi study. the material is unique, as it is based on investigations of a stochastic selection of 1800 buildings (boverket 2009). the estimation was that approximately 66 per cent of all buildings in sweden had some type of damage and 45 percentage of these damages were caused by moisture, which could have an impact on the indoor environment. however, most shortcomings that were registered were not of a serious nature. the cost for remedying all identified damage and meeting needs for maintenance was estimated to between 230 and 330 billion sek (approximately 23-33 billion euros), also including measures for decreasing noise levels in schools. in addition to high costs for remediation, the customers, tenants and users of the buildings lose confidence in the building industry when their buildings are exposed to moisture problems. these problems could have been avoided if moisture issues had been focused on and dealt with throughout the building process. a method for including moisture safety in the building process (byggaf) was developed ten years ago and is referred to in the swedish building regulation bbr and is quite widely used in the swedish building sector. the purpose of the method is to help all the stakeholders involved to work with moisture safety activities and to document them in a structured way. the method includes a number of routines, templates and checklists for clients to formulate requirements for moisture safety and to follow up and document the measures carried out by different participants. there are also tools for architects and design engineers, such as lists of references to literature, checklists and design examples to use for moisture safety design. for contractors, specific routines have been developed for moisture control during construction. the method has been applied to several building projects. based on the experience from these projects, the method and the tools have been evaluated and revised, (mjörnell et al 2012, byggaf 2018). byggaf gives guidance on a very general level and does not provide advice on choice of design of constructions and materials or how to handle wood at the construction site. thus, a specific guide for controlling moisture and mould in wooden constructions exposed to the outdoor climate is needed. a guide with recommendations, based on former research studies performed by the authors, is presented in this paper. methods methods used to investigate moisture condition in swedish wooden buildings a few years ago, there were two large national research initiatives on durability in wooden buildings “future wooden buildings” and “woodbuild”. the outcome of these projects was presented in a number of scientific publications but also as recommendations to the national building industry in sweden. (mundt-petersen 2013, johansson 2014, olsson 2014). journal of sustainable architecture and civil engineering 2019/1/24 32 as part of the program, a number of field studies were made in order to increase knowledge on the hygro-thermal conditions that wooden buildings are exposed to during their lifetime including both construction and operation phase. moisture and temperature conditions in wood were investigated in 24 prefabricated detached houses, three wooden house factories and two apartment buildings, (olsson 2014). wooden sills frequently become wet due to rain during construction. there was however a disagreement between the wooden house industry and the researchers how much water is absorbed and how fast the moisture is drying out. therefore, a laboratory study was designed in order to examine whether wooden sills and wooden studs can withstand short-term exposure to free water, before or after the wall design is closed up with tight layers, and whether there is any risk of mould growth, (olsson and mjörnell 2012). moisture is not only a problem during the erection of wooden buildings but also during the use phase. during the last few decades well-insulated, rendered, unventilated and undrained stud walls have been very popular in sweden. unfortunately, this structure has shown to be sensitive to moisture, especially driving rain. experience from surveys of more than a hundred buildings shows that the problem is that moisture enters the structure – for example, at joints, poor connections to windows and doors, or at fixing studs wetting the materials inside the stud wall and causing mould growth. the damage is never visible on the surface of the wall but is hidden within the wall. the only way to detect the damage is to measure the moisture conditions inside the wall. a national survey was carried out in order to determine the extent of the problem and any connection to local climates, orientation, frequency and direction of driving rain, design of connections, type of plaster (thin or thick), and insulation material (mineral wool or cellular plastic) etc. (samuelsson et al 2008). in addition to that, a number of mock-ups of rendered stud walls of existing and new designs have been tested in the laboratory, complemented by theoretical investigations of heat and moisture conditions in the walls. complementary laboratory studies have been carried out to study how the water droplets enter different types of holes and slits and how different conditions such as pressure difference, the shape of the opening, surface material and dams affect the leakage. (olsson 2018a, olsson 2018b). results results from former research studies on moisture conditions in swedish wooden buildings the results from one of the investigations consist of data on exposure climates during the construction process, moisture ratios in wood and microbiological analyses of wood at all stages from storage at the factory until assembly at site. the conclusion from the study was that climatic conditions to which wood is normally exposed during the construction stage do not seem to contribute to the growth of mould, provided that the wood has not been exposed to free water or has been kept under damp conditions for longer periods of time at favourable temperatures. in this study, microbial growth was found on almost one-third of all the samples taken and elevated and high moisture ratios were found in one-third of all the samples. since the exposure conditions depend to a very large extent on the weather conditions while the building is being erected and before it is weatherproof, the results also seem to indicate that wood can have collected microbial growths before it has reached the manufacturer’s stores or production in the factory. the results of the field measurements at the building sites show that, regardless of the particular manufacturer, the most moisture-exposed and, at the same time, probably the most critical, part of the structure is generally the bottom edge of the outer wall and the sill. the risk of materials being damp, and of microbial growth, can however be reduced by appropriate changes to the method of erection and modifications of the design, or by better weather protection or coverage at the site (olsson et al 2011). 33 journal of sustainable architecture and civil engineering 2019/1/24 the results from the laboratory study on wooden stud walls show that all sill designs tested in the study were damaged by extensive mould growth if they were subjected to water for as short a time as one or three days. mould growth occurred mainly on the material surfaces facing the direction in which drying-out was impeded by the moisture barrier, steel plates or other materials that were damp or impermeable to water vapour. the drying time for sills was at least three to six weeks, depending on the design. many surfaces had no visible mould growth, but when examined under a microscope, the mould growth was extensive. this strengthens the view that microbial analyses are necessary in order to safely determine whether the wood is contaminated by mould. (olsson and mjörnell 2012). the results from this study form the basis for the guidelines for the construction industry on how to design, use, and handle wood in exterior wall designs presented in this paper. recommendations based on research on moisture conditions in swedish wooden buildings in case unforeseen wetting or moistening occur: if there is any suspicion that wood or wooden constructions have been exposed for prolonged moistening or high relative humidity in the surrounding air, a microbiological analysis is needed, or the material needs to be substituted or planed. if the wood or wooden structure has been exposed to short-term shallow moistening caused by precipitation or other water, the moist surfaces of the wood should be dried out immediately, within one day, and be checked by moisture content measurements. if still moist, drying should continue followed by a microbiological analysis. an alternative measure could be to substitute the material or plane away affected parts. if the wood or wooden structure has been exposed for short-term but deep or long-term moistening (several days) precipitation or other water, the wood should be dried out and the drying process should be checked by measuring the moisture content. after finished drying, a microbiological analysis should be made to ensure that there is no presence of microbiological growth. alternatively, the wood should be substituted, or the surface should be planed. by the time the house is tight, and the surfaces are not in direct contact with outdoor air the following should be applied: the climate should be controlled. the moisture content in the indoor air should be restricted and additional moisture should be prevented by for example ventilation or dehumidification. continuous monitoring of relative humidity and temperature is needed to control the amount of additional moisture and assure a sufficiently dry drying climate. heating usually speeds up the evaporation of moisture from materials and could be a prerequisite for reducing the drying time in order to keep the time plan of construction. increased temperature often leads to an increased moisture content in the air and risk of condensation or high moisture levels at cold surfaces or in air-leaky structures. good air-tightness is needed to avoid moist air to penetrate through the wooden structure. perform moisture rounds at the building site, at least ones a week, proposed according to the routine in byggaf (byggaf 2018). discussion the main problem with wood as a construction material is that it is sensitive to moisture and water causing mould and in several cases rot damages, as well as insect pests, which might cause indoor air problems but also structural failures shortening the lifetime of the building. during the construction phase, there is a high risk of microbiological growth if the wood is exposed to water. if the wood has been exposed to water or high moisture levels there the margins are small before mould starts to grow. at favourable conditions such as high temperatures and humidity, which is common during summertime, mould growth may start within a few weeks but if the wood gets wet, mould growth may occur within a few days. there are also risks for cracks due to shrinking when the wood dries, which may affect tight layers in the house. at low temperatures, the mould growth is slower but on the other hand, the drying out takes much longer time. also, well-insujournal of sustainable architecture and civil engineering 2019/1/24 34 lated buildings have a lower drying out potential than poorly insulated buildings. drying of wood is quite slow, especially if the water has been sucked into joints or connections between wood and other materials. there is a disagreement in the construction sector whether it is necessary to use weather protection when assembling wooden buildings. on the other hand, there is no doubt that wood must be protected from moisture and water. to neglect wetting or moistening of wood during construction could imply costs for repairing damages which must be calculated for. such damages also involve an increased cost for investigation, microbiological analyses, drying out, decontamination of surfaces or substitution of materials. if weather protection is not used, extensive control of moisture conditions and microbiological growth on wood constructions is needed to assure moisture safety throughout the construction time. the risk of damages can be reduced by using weather protection. conclusions during the last decades, many swedish municipalities have required building in wood to meet the ambitious environmental targets involving decreasing the carbon footprint. the advantages of wood construction may be jeopardized if subjected to discussions about moisture risks and increased costs and environmental impact due to a replacement of material in case of damages. the best strategy to assure a moisture safe construction is to make sure that wood is not exposed to water or long periods of high relative humidity, which means that moisture safe, robust structures, weather protection and moisture safe construction methods must be used. to neglect moisture safety could imply a high risk of damage with extensive costs for investigations, decontamination or substitution of material, and time delays as consequences. acknowledgment the research which forms the basis of the recommendations presented in this paper was carried out within the research programs “framtidens trähus” (future wooden buildings) and “woodbuild” founded by vinnova, sweden’s innovation agency. references boverket (2009). så mår våra hus – redovisning av regeringsuppdrag beträffande byggnaders tekniska utformning m. m. isbn pdf: 978-91-86342-29-6. byggaf (2018). method for moisture safety in the building process. http://www.fuktcentrum.lth.se/ verktyg-och-hjaelpmedel/fuktsaekert-byggande/ byggaf-metoden/ access date 2018-12-18. früwald-hansson, e., bardage, s. and thelandersson, s. (2013) modelling the risk for mould growth on timber stored outdoors protected from rain. proceedings of 44th irg annual meeting in stockholm, irg/wp 13-20529. johansson, p. (2014). determination of the critical moisture level for mould growth on building materials, rapport tvbh-1020 lund 2014. https://lup.lub.lu.se/ search/publication/72d4403b-3b90-4c71-9aee-8aa8dbebc79e mjörnell, k., arfvidsson, j., & sikander, e. (2012). a method for including moisture safety in the building process. indoor and built environment, 21(4), 583– 594. https://doi.org/10.1177/1420326x11428340 mundt-petersen s. o. (2013) moisture safety in wood frame walls blind evaluation of the hygrothermal calculation tool wufi 5.0 using field measurements and determination of factors affecting the moisture safety. tvbh-3059. olsson, l. mjörnell, k. johansson, p. (2011). moisture and mould in prefabricated timber frame constructions during production until enclosure of the house: proceedings of the 9th nordic symposium on building physics (nsb 2011), tampere, finland, may 29-june 2, 2011, pp. 339-346. olsson, l., mjörnell, k. (2012). laboratory investigation of sills and studs exposed to rain, proceedings of the 5th ibpc, kyoto, japan, may 28-31, 2012. olsson, l. (2014). moisture conditions in exterior wooden walls and timber during production and use. licentiate thesis 2014:2 chalmers university of technology. isbn no. 1652-9146. olsson, l. (2018a). rain resistance of façades with façade details: a summary of three field and laboratory studies. journal of building physics, 41(6), 521– 532. https://doi.org/10.1177/1744259117713265 olsson, l. (2018b). driving rain tightness, intrusion rates and phenomenology of leakages in defects of facades: a new calculation algorithm. phd the35 journal of sustainable architecture and civil engineering 2019/1/24 sis. chalmers university of technology. isbn: 97891-7597-813-0. smart housing småland (2018). http://smarthousing.nu/en/ access date 2018-12-17. samuelson, i., mjörnell, k., jansson, a. (2008). moisture damage in rendered, undrained, well insulated stud walls. proceedings of the 8th symposium on building physics in the nordic countries, vol. 3, p 1253-1260. copenhagen, denmark ss-en 12865. thelandersson, s., isaksson, t. (2013) mould resistance design (mrd) model for evaluation of microbiological growth under varying climate conditions. building environment (65), pp 18-25. https://doi. org/10.1016/j.buildenv.2013.03.016 trästad 2012, wood city sweden (2018). http:// www.trastad.se/english/ access date 2018-12-17. kristina mjörnell vp businessand innovation area sustainable cities and communities rise research institutes of sweden adjunct professor division of building physics at lund university main research area moisture safety, energy efficient buildings, sustainable renovation address eklandagatan 86, 412 66 gothenburg tel. +46 730 88 57 45 e-mail: kristina.mjornell@ri.se about the authorslars olsson senior researcher rise research institutes of sweden main research area moisture safety, rain intrusion, facades, wooden structures, quality assurance address box 857, 501 15 borås, sweden tel. +46 705 85 09 08 e-mail: lars.olsson@ri.se 14 building a green roof in lithuania james n. ferguson1* 1 senojo miesto architektai (sma), šv. ignoto 5, lt-01120 vilnius, lithuania * corresponding author: ferguson_vilnius@yahoo.com green roofs are relatively new to lithuania. traditionally, such earth structures were used for partially submerged food cellars and bomb shelters. however, one sees more and more architects opting for green roofs as an alternative to large flat roofs. the advantages are many fold. a green roof is not only a pleasing aesthetic alternative, but it helps retain thermal energy and provides for better surface drainage for expansive roofed structures. this paper examines the origins, basic principles and benefits of green roofs, noting examples and a chart indicating various green roof systems. the international standard is largely set by the forschungsgesellschaft landschaftsentwicklung landshaftsbau e. v., or more simply fll, first developed in germany in the 1970s. i have designed five green roof projects in lithuania. two are located in trakai, two in vilnius, and one in the ignalina region. precedents are cited, along with photos, technical drawings, structural details, materials specifications and the ecological benefits these roofs provide in urban and rural environments. in conclusion, green roofs are a relative low cost alternative to flat roofs, which provide greatly enhanced benefits. as a result, european cities have set targets for the percentage of green roofs constructed each year, and the european union has offered financial aid and assistance in meeting these targets. hopefully, this will encourage more lithuanian developers, architects, and engineers to consider green roofs as a viable solution. keywords: green roofs, sustainable design, architecture. darnioji architektūra ir statyba 2012. no. 1(1) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction it has been a long uphill battle to interest clients in green roofs, solar power and other forms of passive energy roofs, since i came to lithuania in 1997. my first major commission came in 2005, when asked to re-design an antique automobile museum in trakai. the client had to go underground with his museum to satisfy trakai historic planning ordinances and what better way to top such a museum than with a green roof that melded into the surrounding landscape with guest houses built atop in the traditional style, effectively disguising the 4000 sq. meter museum below. since that time, i’ve had the opportunity to design several other green roofs, ranging from a residential complex in užupis to a roof top for the ruins of a 19th century stone barn at paliesiaus estate in the ignalina region (fig. 1). currently, i am working on a green roof for a new sports hall for the american international school fig. 1. paliesiaus estate, ignalina region http://dx.doi.org/10.5755/j01.sace.1.1.2612 15 of vilnius. surprisingly, what links all these roofs is not their environmental benefits, but rather their adaptability to historical sites in urban, small town and rural settings. the last 7 years have seen the proliferation in sustainable design in lithuania, due to greater awareness in alternative forms of construction and increased availability of products in the country. there is even now a solar panel manufacturing plant outside vilnius, which should make these panels more affordable in the years to come. in this paper i will demonstrate the advantages of a green roof over traditional roof types, and how such roofs can be integrated with other passive energy systems like solar panels to reduce energy needs. 2. origins the green roof is certainly nothing new. roofs made of earth go back to prehistoric times and were used for habitation and food storage. a thick green roof provided protection against piercing cold or searing heat, with examples found as far distant as norway and tanzania. thick mud walls combined with a timber frame and earth roof served as the basis for the famous pueblo architecture of the american southwest. a reed underlayer would swell during rains to become virtually waterproof against the elements. these traditional forms of architecture gave way to other forms over the centuries. roof gardens were revived in the late 19th and early 20th century. these terraced roofs were seen as a luxurious addition to city hotels as well as rural mansions, offering great views across the city and country estates. le corbusier was the first modern architect to champion the roof garden in his immuebles-villa of 1925, and incorporated roof gardens into his early villa designs. however, as christian werthmann noted in his book green roof – a case study, le corbusier’s vision gained little traction, despite the popularity of flat roofs among developers. it wouldn’t be until the 1970s that green roofs took hold in germany, with advocates stressing its environmental benefits. a number of pioneering studies were done in regard to effective waterproofing materials, the best organic covers and the benefits such roofs provided. the forschungsgesellschaft landschaftsentwicklung landshaftsbau e. v., or more simply fll, was formed during this time with a commitment to green roof design. studies revealed the most drought-resistant plants with the least amount of subsoil for lightweight, low-maintenance roofs that would “green” cities like stuttgart. today, germany leads the world in adding approximately 8 square kilometers of green roofs per year, which amounts to 7% of all new roofs in the country. 3. basic principles there are essentially two types of roofs with vegetation – the green roof and the roof garden. the green roof is an extensive roof with minimal soil mix or mineral substrate supporting a thin layer of vegetation, usually sedum, which requires little maintenance. the roof garden is more intensive, using a greater amount of topsoil to allow for a richer variety of plant life and formation of small hills, and is usually accessible to people. there are many hybrid forms, adapted to specific environments. the green roof is the most common as it is the most cost-effective. there is little additional cost in providing a thin layer of topsoil to support sedum, which can survive in most locations. sedum, or stonecrop, comes in many varieties and colors, has very shallow roots and can absorb up to 50% of its weight in rainwater, thereby alleviating drainage problems typically associated with flat roofs. the lightweight roof (37 kg/m³) can be adapted to virtually any building without added structural support. it comes in blankets that can be rolled out on a minimum of 20 mm of mineral substrate. it also comes in easy to grow kits for smaller roofs. typically, these roofs are not accessible and require minimal upkeep. the garden roof offers a wider range of opportunities, especially for those who want to make the roof an active part of the building, as le corbusier had envisioned in his five points of architecture. a minimum of 150 mm of topsoil is required to grow a greater variety of plant life. this of course adds considerable weight to the roof and would require additional structural reinforcement. however, the benefits often outweigh the costs, as the roof literally becomes an extension of the building and can be used in a number of creative ways, as was the case with le corbusier’s la tourette monastery in southern france. hybrid roofs combine features noted above as well as introduce additional elements such as small structures and passive energy systems like solar and wind power. a great number of creative designs have been proposed, such a mvrdv’s dutch pavilion for the hanover exposition of 2000, which was an artificial ecosystem based on various dutch landscapes with modern wind turbines. 4. benefits these roofs provide a number of positive features. typically they are seen as ecological improvements, providing an additional layer of green to a city, or melding a building into a rural landscape so that it looks less intrusive. the major benefit of a green roof is stemming the flow of water off a roof. hard roofs offer no resistance to rain water. during a heavy rainstorm, massive amounts of water flood an often overloaded city drainage system. a green roof or garden roof absorbs and filters rainwater, relieving the amount of water flowing into a rain water drainage system. another benefit is noise reduction. it has been shown that a typical lightweight green roof reduces sound by 5 decibels. the thicker the roof garden the more noise is dampened. this is particularly beneficial in loud urban environments. a thin sedum-covered rooftop blocks out uv light, increasing the life of the waterproof membrane. the roots do not penetrate membranes, but an additional protective layer is advisable for wind blown seeds that may take root on the roof. a green roof also serves as a passive roof covering that lessens heat gain. typical roof surface materials often absorb heat and make a building harder to ventilate and 16 cool in warm months. even the lightest green roof is a vast improvement over typical asphalt and gravel flat roofs. a thicker roof garden would provide an additional layer of thermal insulation in winter. still the greatest benefit is increasing the amount of green space in a city. it has been shown that cities with the largest percentage of green roofs, like stuttgart, have actually seen a slight ambient decrease in air temperature. typical roofing materials increase the heat in a city, making some cities incredibly stifling during the hottest summer months. active roof gardens not only increase the biodiversity of a city, but provide a new level of agricultural gardening in densely packed cities. all this additional vegetation also helps absorb the high levels of carbon dioxide common in metropolitan centers. 5. projects the urban green roof i’ve had the opportunity to design two urban green roofs in vilnius. both share the similar feature of being extensions of the surrounding hillside, as to satisfy municipal zoning conditions. the first was a terraced garden roof for a residential complex in užupis. the client wanted 40 individual units built into a hillside with underground parking. there was a limited amount of space to achieve the number of units the client desired. i used a green terrace to provide for a second level of outdoor living for the units above. as this would all be active space, i proposed the structure be designed to support a minimum of 30 centimeters of topsoil with a combination of terrace features. unfortunately, the project was not realized due to the economic crisis of 2008. since then i have been working on a new sports hall for the american international school of vilnius. the school is located on a narrow strip of land on the north side of subačius st., neighboring two historic monasteries. there was a limited amount of space between the school and the steep hillside which was under protection. we were able to get preliminary approval from the municipal planning and the cultural heritage departments by burying the sport hall into part of the hillside, which had once served as a playground. the sports hall literally became an extension of the hillside with an earth roof, making it invisible from the air. we recently completed a preliminary technical project, pending approval of the detail plan. the roof structure is made from 10 cm deep corrugated metal sheets supported by pre-fabricated steel trusses at 6 meters on center. a 5 cm air space separates the insulated layer from the earth roof, with drainage filtered to a channel at the juncture with the hillside, which feeds into the storm water drainage system. table 1. green roof systems (conversion factor 1 inch = 2.54 cm) 17 fig. 2. site model both projects presented numerous challenges. as is often the case in such projects, the developers wanted to maximize the building intensity of the site. both sites were irregular in shape and didn’t allow for conventional building solutions. the green roofs grew out of largely pragmatic responses to the sites, not ecological ones. once the clients became interested in the ecological benefits, the focus shifted toward creating sustainable designs that in the first case would attract prospective homeowners and in the second case eu funding. the school is now seeking funding for a geothermal system to heat and cool the school and sports hall. going underground two other opportunities for green roofs arose in trakai, where my wife and i have done several small projects and have an ongoing site improvement project with the trakai national historic park at užutrakis. we were first approached by a client looking to expand an antique automobile museum he had received approved for construction. he owned a highly visible site with an historic brick house at one corner that had to be restored to its original appearance. his collection of antique cars had greatly increased since he first considered the project and had since bought neighboring parcels of land, which allowed him up to 4000 square meters of underground area. the city was keen on the idea, as they felt it would be a valuable new tourist attraction, but the national park was skeptical of such a large underground structure and roof top. we alleviated the national park’s concern by landscaping the roof top in keeping with the contours of the original site. the roof structure is a two-way reinforced concrete slab with reinforced concrete columns with massive reinforced capitals. the structural engineer expressed concerned over the load of the landscaping on the roof slab, but there are many ways to alleviate such loads by forming contours and hills out of lightweight materials and laying a relatively light subsoil on top, using the hidden space for light wells or storage. christian werthmann noted the innovative ideas of michael van valkenburgh in the green roof he designed for the existing headquarters of the american society of landscape architects in washington, dc. construction began in 2006 with one-quarter of the underground structure complete by 2008, at which time work was suspended due to the crisis. the owner continues his efforts to secure financing to complete the project. during this time we received a commission for a second large project in trakai, the reconstruction of the nendre restaurant into a hotel and spa complex, approximately 2500 square meters. the greatly expanded structure grew out of the original footprint of the building and continued along the ridge facing the lake. the green roof would have risen from grade to the high point of the roof. it was quite a departure from the traditional forms that the national park advocated, but we were able to convince the park that this was the best solution to the site as it would have a low profile toward the castle and be far less intrusive than is the original nendre structure. unfortunately, the client chose not to proceed with the project beyond the approved proposal and detail plan. j. n. ferguson 20 sustainable designs that in the first case would attract prospective homeowners and in the second case eu funding. the school is now seeking funding for a geothermal system to heat and cool the school and sports hall. going underground two other opportunities for green roofs arose in trakai, where my wife and i have done several small projects and have an ongoing site improvement project with the trakai national historic park at užutrakis. we were first approached by a client looking to expand an antique automobile museum he had received approved for construction. he owned a highly visible site with an historic brick house at one corner that had to be restored to its original appearance. his collection of antique cars had greatly increased since he first considered the project and had since bought neighboring parcels of land, which allowed him up to 4000 square meters of underground area. the city was keen on the idea, as they felt it would be a valuable new tourist attraction, but the national park was skeptical of such a large underground structure and roof top. we alleviated the national park’s concern by landscaping the roof top in keeping with the contours of the original site. the roof structure is a two-way reinforced concrete slab with reinforced concrete columns with massive reinforced capitals. the structural engineer expressed concerned over the load of the landscaping on the roof slab, but there are many ways to alleviate such loads by forming contours and hills out of lightweight materials and laying a relatively light subsoil on top, using the hidden space for light wells or storage. christian werthmann noted the innovative ideas of michael van valkenburgh in the green roof he designed for the existing headquarters of the american society of landscape architects in washington, dc. construction began in 2006 with one-quarter of the underground structure complete by 2008, at which time work was suspended due to the crisis. the owner continues his efforts to secure financing to complete the project. fig. 3. site section during this time we received a commission for a second large project in trakai, the reconstruction of the nendre restaurant into a hotel and spa complex, approximately 2500 square meters. the greatly expanded structure grew out of the original footprint of the building and continued along the ridge facing the lake. the green roof would have risen from grade to the high point of the roof. it was quite a departure from the traditional forms that the national park advocated, but we were able to convince the park that this was the best solution to the site as it would have a low profile toward the castle and be far less intrusive than is the original nendre structure. unfortunately, the client chose not to proceed with the project beyond the approved proposal and detail plan. a protective green roof we were approached to design a country tourism complex on the grounds of the former paliesiaus estate in the ignalina region in 2008. the only remaining structures were two stone barns that served the estate, both in very bad condition. the first barn (see figure 1) was able to be restored, since it still had its structure relatively intact, but the more interesting semi-circular barn was in a complete state of ruins. the question became whether to reconstruct the second barn to its original appearance or take another approach. i suggested stabilizing the ruins and placing a green roof over the structure to protect it. the three wedge-shaped rooms could be converted into a spa to serve the guest rooms in the other restored barn. both the cultural heritage dept. in utena and the city commission in ignalina liked the idea and approved all the documents. the shed roof is approximately 900 square meters in area and is constructed from glu-lam beams atop similar glu-lam girders, supported by 33 cm. diameter wood laminated columns, with an 8 cm. insulated layer and a 10 cm. ventilated air space below the 15 cm. earth covering. the ventilated air space will help to avoid condensation between the insulation and the earth covering. construction began in late 2011, and the first part of the project should be complete by january, 2013. fig. 3. site section 165.60 (12.88) 164.20 (11.48) 163.60 (10.88) 161.60 (8.88) 159.82 (7.10) 156.60 (3.88) 152.72 (0.00) 151.42 (-1.30) 150.42 (-2.30) 160.42 (7.70) 163.60 (10.82) 161.82 (9.20) 158.60 (5.88) 155.22 (2.50) 152.70 (0.00) 150.42 (-2.30) 18 a protective green roof we were approached to design a country tourism complex on the grounds of the former paliesiaus estate in the ignalina region in 2008. the only remaining structures were two stone barns that served the estate, both in very bad condition. the first barn (see figure 1) was able to be restored, since it still had its structure relatively intact, but the more interesting semi-circular barn was in a complete state of ruins. the question became whether to reconstruct the second barn to its original appearance or take another approach. i suggested stabilizing the ruins and placing a green roof over the structure to protect it. the three wedgeshaped rooms could be converted into a spa to serve the guest rooms in the other restored barn. both the cultural heritage dept. in utena and the city commission in ignalina liked the idea and approved all the documents. the shed roof is approximately 900 square meters in area and is constructed from glu-lam beams atop similar glu-lam girders, supported by 33 cm diameter wood laminated columns, with an 8 cm insulated layer and a 10 cm ventilated air space below the 15 cm earth covering. the ventilated air space will help to avoid condensation between the insulation and the earth covering. construction began in late 2011, and the first part of the project should be complete by january, 2013. building a green roof in lithuania 21 fig. 4. section drawing fig. 5. roof detail 6. conclusions the green roof is a relatively low cost solution that has been demonstrated to have many benefits to the building owner, both in terms of pragmatic concerns and environmental impact. yet, there is only a relative handful of earth roofs in lithuania. waterproofing remains the principal concern, but lightweight sedum roofs can be installed on virtually any existing flat roof, increasing the life span of the roof, reducing heat gain, and easing storm water drainage. william mcdonough and michael braungart noted in their book, cradle to cradle, that they convinced ford motor company of the benefit of green roofs, retrofitting sedum roofs on existing manufacturing plants, greatly reducing cooling costs in summer. new roofs can be designed with greater landscaping loads in mind and formed into existing hillsides or used to “conceal” buildings in urban and historically significant locations. we found that building context models for the american international school and the užupis housing project convinced city and cultural heritage department officials that the new proposed buildings would have a relatively low impact on sensitive sites. however, it is important to think beyond individual solutions and pursue broad range planning, as has been the case in stuttgart, germany, where city officials have set long term goals for the percentage of green roofs. building a green roof in lithuania 21 fig. 4. section drawing fig. 5. roof detail 6. conclusions the green roof is a relatively low cost solution that has been demonstrated to have many benefits to the building owner, both in terms of pragmatic concerns and environmental impact. yet, there is only a relative handful of earth roofs in lithuania. waterproofing remains the principal concern, but lightweight sedum roofs can be installed on virtually any existing flat roof, increasing the life span of the roof, reducing heat gain, and easing storm water drainage. william mcdonough and michael braungart noted in their book, cradle to cradle, that they convinced ford motor company of the benefit of green roofs, retrofitting sedum roofs on existing manufacturing plants, greatly reducing cooling costs in summer. new roofs can be designed with greater landscaping loads in mind and formed into existing hillsides or used to “conceal” buildings in urban and historically significant locations. we found that building context models for the american international school and the užupis housing project convinced city and cultural heritage department officials that the new proposed buildings would have a relatively low impact on sensitive sites. however, it is important to think beyond individual solutions and pursue broad range planning, as has been the case in stuttgart, germany, where city officials have set long term goals for the percentage of green roofs. fig. 4. section drawing fig. 5. roof detail 19 6. conclusions the green roof is a relatively low cost solution that has been demonstrated to have many benefits to the building owner, both in terms of pragmatic concerns and environmental impact. yet, there is only a relative handful of earth roofs in lithuania. waterproofing remains the principal concern, but lightweight sedum roofs can be installed on virtually any existing flat roof, increasing the life span of the roof, reducing heat gain, and easing storm water drainage. william mcdonough and michael braungart noted in their book, cradle to cradle, that they convinced ford motor company of the benefit of green roofs, retrofitting sedum roofs on existing manufacturing plants, greatly reducing cooling costs in summer. new roofs can be designed with greater landscaping loads in mind and formed into existing hillsides or used to “conceal” buildings in urban and historically significant locations. we found that building context models for the american international school and the užupis housing project convinced city and cultural heritage department officials that the new proposed buildings would have a relatively low impact on sensitive sites. however, it is important to think beyond individual solutions and pursue broad range planning, as has been the case in stuttgart, germany, where city officials have set long term goals for the percentage of green roofs. the eu is now actively promoting green roofs in new construction across europe. similar measures can be adopted in cities in lithuania, which would encourage developers, architects and engineers to consider green roofs in their new designs. the forschungsgesellschaft landschaftsentwicklung landshaftsbau (fll) provides the necessary standards. the main website is in german, but various translations can be found on other websites. (i. gurauskiene, 2006, ecodesign methodology for electrical and electronic equipment industry). references betsky a. 2002. landscrapers: building with the land. thames and hudson. breuning j., yanders, a. 2008. edition of the green roofing guideline, introduction to the fll guidelines for the planning, construction and maintenance of green roofing. costanzo, m. 2006. mvrdv: works and projects 1991-2006, dutch pavilion. skira. margolis l., robinson, a. 2007. living systems. birkhäuser. mcdonnough w., braungart m. 2002. cradle to cradle. north point press. werthmann ch. 2007. green roof – a case study. princeton architectural press. individual projects cited as examples can be viewed at: http://www.ferguson-studio.com (accessed 17 may 2012). received 2012 06 21 accepted after revision 2012 09 03 james n. ferguson – architect at senojo miesto architektai (sma). address: senojo miesto architektai (sma), šv. ignoto 5, lt-01120 vilnius, lithuania. e-mail: ferguson_vilnius@yahoo.com journal of sustainable architecture and civil engineering 2020/1/26 36 *corresponding author: etousi@uniwa.gr policies for environmental awareness in tourist accommodation. the case of greece received 2019/06/28 accepted after revision 2020/01/21 journal of sustainable architecture and civil engineering vol. 1 / no. 26 / 2020 pp. 36-46 doi 10.5755/j01.sace.26.1.23607 policies for environmental awareness in tourist accommodation. the case of greece jsace 1/26 http://dx.doi.org/10.5755/j01.sace.26.1.23607 orfanoudaki chara architect, post-graduate student, environmental design, school of science and technology, hellenic open university, parodos aristotelous 18,26335, patra, greece tousi evgenia* dr.architect-urban and regional planner, adjunct academic staff, environmental design, school of science and technology, hellenic open university, parodos aristotelous 18,26335, patra, greece introduction keywords: energy efficiency, tourist accommodation, greece, energy upgrading. tourism is the third largest socio-economic activity in the european union (juul, 2015). non-residential buildings represent 25% of the total number of buildings in europe, with hotels and restaurants possessing 11% of it (economidou, et al., 2011). the highest energy consumption in the tourist area can be found in the subareas of transportation and accommodation. regarding the area of accommodation, there is a great demand for cooling/heating systems, lighting, laundry facilities, kitchens, swimming pools and salt water desalination (coastlearn, 2019). moreover, increased tourist activity in recent years has been putting pressure on the natural and the human environment since it results in an expansion of the building area and the necessary infrastructures, an increasing demand for energy, and perturbation of ecosystems (parpairi, 2016). furthermore, hotel accommodation is considered to comprise buildings of the tertiary sector with the highest energy consumption, as they are structures with various operational features and a large number of users (farrou, 2013). as regards greece, tourism is the main pillar of economy, contributing to the country’s gdb by 18% in total, possessing 23.1% of the total workforce in 2015 (wttc, 2016). electricity is the main source of energy used in hotel accommodation around greece. it is used for air conditioning, lighting, laundry machines, tumble dryers and appliances used in the kitchen (maleviti etc, 2011). petroleum is the fuel ranking second in use, mainly covering the need for heating and hot water, while liquid gas is used for covering the same needs but in fewer hotels (ibid). natural gas is used mainly in hotels located in urban centres, where there is access to natural gas supply. in addition to high energy consumption in the buildings of the tourism sector, there is also a high demand for water supply (ghaitidak &yadav, 2013). this phenomenon is crucial for some areas in greece. typical examples of such areas are those with serious water scarcity during the period of increased tourist activity. such areas are the aegean islands during the summer months (alexandri, 2012). 37 journal of sustainable architecture and civil engineering 2020/1/26 the importance of this issue is presented in a 2015 report of the world economic forum on global hazards, where water crisis is ranked as the greatest impact of hazards worldwide (waterfootprintnetwork, 2017). on account of all these, modern economies have implemented green policies on the sector of tourism as a necessary step for sustainable development. after the 90s, environmental awareness programs like the “international hotels environmental initiative” (ihei) state the ever-increasing interest for sustainable tourist accommodation. the contribution of the sector of tourism in the field of energy efficiency has been expressed through agenda 21 for tourism and travel industry. agenda 21 focuses on resource management and energy use in order to improve environmental standards. despite the criticality of the issue, former studies lack sector specialisation, examining together different types of tourist facilities and accommodation (becken et.al, 2001). one such example is the commercial buildings energy consumption and expenditure undertaken by the u.s. energy information administration (eia, 1995). another issue is the lack of comprehensive research on energy use patterns as far as tourist accommodation is concerned (becken et.al, 2001). in the previous decades, various research programs based on pilot case studies aimed at the improvement of the ecological footprint of tourist accommodation. as for the european union, policies associated with eu targets for 2020 and 2050, conclude to programs like the nezeh (nearly zero energy hotels). this program is considered to be a direct response to the european directive on the energy performance of buildings (2010/31/eu, epbd recast). its scope was to foster large scale renovations of existing hotels into nearly zero energy buildings (nzeb). greece as a member state of the european union, participated in the nezeh program. however, a variety of interrelated factors affecting the role and function of the tourist industry in greece sets barriers to energy efficiency. taking into consideration all the above along with the fact that in greece there are no statistical data for energy consumption in the tourism sector, this research provides useful information regarding environmental awareness in tourist accommodation. the aim of this research is not only to designate the implemented good practices but also to highlight the crucial factors that impede further development on the field. in this context, this research presents an assessment of the effectiveness of the green tourism program which has contributed to the energy upgrading of the existing hotels in greece during the period 2007-2013. methods the methods used in this research include literature review on the issue of energy efficiency in tourist accommodation combined with analysis of official statistical data taken from the hellenic statistical authority and the ministry of economy. furthermore, field work was conducted in the area of attica. to be more specific, following a request to the relative department of the greek ministry of finance, unpublished data of the green tourism project were supplied and analysed by the authors. these data, presented in this paper, outline the situation in greece regarding recent green strategies followed after the kyoto protocol. moreover; the research has carried out an in-depth investigation into the case of the metropolitan area of the capital of greece through field work. this area was selected as a characteristic case study because of the fact that there is significant tourist inflow throughout the whole year. field work focused on qualitative research with the help of structured interviews addressed to the hoteliers involved in the green tourism program. the thematic units of the questionnaire included the number and sort of completed interventions on the building shell, the application of renewable energy sources, the percentage of energy saving, the percentage of the reduction of water consumption and the percentage of capital amortization. the study draws useful conclusions concerning the policies implemented to date, providing guidelines for further improvement considering energy consumption of building shells in the tourist industry in greece. journal of sustainable architecture and civil engineering 2020/1/26 38 although hotels in greece comprise 0,26% of the total number of buildings according to a study in 2007, they consume 29% of the energy consumed totally by the private sector (maleviti etc, 2011). consequently, they demonstrate very high rates of energy consumption, using mainly electricity and petroleum, as they keep a large number of different appliances and provide various services (ibid). more analytically, as illustrated in the graph1, hotels in greece display an average energy consumption of 290 kwh / m2 / year, 48% of which is for heating and cooling, 7% is for lighting, 13% for hot water and 25% for cooking (nezeh, 2016). after the kyoto protocol, changes in european and greek legislation led to a number of measures for energy upgrade and certification of buildings of all kinds of usage, including tourist accommodation. a concise analysis of relevant legislation is cited further below for a better description of the green tourism programme, which is the main policy of the country for upgrading hotel accommodation in terms of energy. the kyoto protocol recognises that developed countries are responsible for the emission of greenhouse gases and includes the necessary steps for a long run response to the challenges of climate change caused by an increase in results graph 1 energy consumption in hotels (nezeh,2016) the man-made emissions of greenhouse gases (unfccc, 2019). according to this, the countries that have signed pledge to reduce gas emissions during the first period of assuming responsibility (2008-2012) by at least 5% by the year 2012 with specific actions according to the policy and measures to be defined (υpεκα). legislation led to a number of measures for energy upgrade and certification of buildings of all kinds of usage, including tourist accommodation. a concise analysis of relevant legislation is cited further below for a better description of the green tourism programme, which is the main policy of the country for upgrading hotel accommodation in terms of energy. the kyoto protocol recognises that developed countries are responsible for the emission of greenhouse gases and includes the necessary steps for a long run response to the challenges of climate change caused by an increase in the manmade emissions of greenhouse gases (unfccc, 2019). according to this, the countries that have signed pledge to reduce gas emissions during the first period of assuming responsibility (2008-2012) by at least 5% by the year 2012 with specific actions according to the policy and measures to be defined (υpεκα). graph 1: energy consumption in hotels (nezeh,2016) greece signed the protocol in april 1998, together with the other member states of the eu and the european commission. all eu member states sanctioned the protocol in may 2002. greece sanctioned it with the law 3017/2002 (fεκ α'117) (υpεκα).on this basis and with the aim to comply with the kyoto protocol and the agreement-framework of the united nations for the climate change, the european commission issued guideline 91 (91/2002/εc) in 2002, where the term “energy efficiency of buildings” was mentioned for the first time. in addition, measures for the reduction of energy consumption associated with buildings were suggested. greece conformed to 2008 guideline 91, when law 366 (l.3661/2008,fεκ α'89) was issued, where it was reported that the regulation for energy consumption of buildings was to be set, which foresees the minimum requirements for energy efficiency of buildings. in 2010, the european union issued guideline 31 (2010/31/εu), where it was stipulated that after 2020 all newly erected buildings will have to be of zero energy consumption. greece incorporated guideline 31 into law 4122 (l.4122/2013, fεκ α'42), in which energy efficiency of buildings was mentioned. in the same direction, with the aim to reduce energy consumption from conventional sources and promote sustainable development in the member states of the union, in 2010 the european commission announced energy strategy “europe 2020”, which is widely known also as “strategy 20-20-20” (georgarakis etc,2017). regarding energy consumption of buildings in greece, initially with the presidential decree of 1.6/1979 there was an introduction of the regulation for thermal insulation of buildings (r.t.b), which defined the requirements for thermal insulation of all newly erected buildings. in 2002, the buildings energy efficiency regulation (κενακ) was enacted, which replaced the r.t.b and defined the minimum energy efficiency requirements of buildings. in 2010, kenak (κ.υ.α 5825/2010) was greece signed the protocol in april 1998, together with the other member states of the eu and the european commission. all eu member states sanctioned the protocol in may 2002. greece sanctioned it with the law 3017/2002 (fεκ α’117) (υpεκα).on this basis and with the aim to comply with the kyoto protocol and the agreement-framework of the united nations for the climate change, the european commission issued guideline 91 (91/2002/εc) in 2002, where the term “energy efficiency of buildings” was mentioned for the first time. in addition, measures for the reduction of energy consumption associated with buildings were suggested. greece conformed to 2008 guideline 91, when law 366 (l.3661/2008,fεκ α’89) was issued, where it was reported that the regulation for energy consumption of buildings was to be set, which foresees the minimum requirements for energy efficiency of buildings. in 2010, the european union issued guideline 31 (2010/31/εu), where it was stipulated that after 2020 all newly erected buildings will have to be of zero energy consumption. greece incorporated guideline 31 into law 4122 (l.4122/2013, fεκ α’42), in which energy efficiency of buildings was mentioned. in the same direction, with the aim to reduce energy consumption from conventional sources and promote sustainable development in the member states of the union, in 2010 the european commission announced energy strategy “europe 2020”, which is widely known also as “strategy 20-20-20” (georgarakis etc,2017). regarding energy consumption of buildings in greece, initially with the presidential decree of 1.6/1979 there was an introduction of the regulation for thermal insulation of buildings (r.t.b), which defined the requirements for thermal insulation of all newly erected buildings. in 2002, the buildings energy efficiency regulation (κενακ) was enacted, which replaced the r.t.b and defined the minimum energy efficiency requirements of buildings. in 2010, kenak (κ.υ.α 5825/2010) was issued. kenak had been forceable from 2010 to 2017, when it was reviewed with fεκ β’ 2367/12-7-2017 and was replaced with the new kenak, which incorporated the new european 39 journal of sustainable architecture and civil engineering 2020/1/26 guideline 31 of 2010.the purpose of kenak is to specify and institutionalize the energy planning of the building sector, according to the european instructions for saving energy and protecting the environment (fek 5447/b/5-12-2018). kenak configures a context of principles and rules with the aim to improve the energy efficiency of buildings by reducing the consumption of conventional energy for heating, cooling, air conditioning and lighting of spaces as well as the production of hot water for use, without disturbing the conditions of thermal and visual comfort (fεκ β΄ 407, 2010). in this spirit, the “green tourism” programme was an initiative of the greek department of tourism, in the context of the “competitiveness and entrepreneurship” european project 20072013. the main target was the support of investments in hotels and tourist accommodation of the greek domain so that environmental awareness and corporate social responsibility of businesses would be developed, the services offered as well as their environmental performance would be upgraded and appropriate infrastructure would be created in order to fulfill the criteria required so as to be certified according to one of the existing certification systems for their environmental behaviour (φεκ 2763, 2014). in this direction, the businesses interested were called to submit their propositions whose aim was to upgrade infrastructures and their operation ecologically, always taking into consideration both each place’s geological features and each business’s particularities (fεκ 2763, 2014). in a more detailed analysis, the programme required a set of targets which had to involve the improvement of energy efficiency of the hotel and accommodation buildings resulting in saving energy, managing water and the waste produced by them as well as incorporating procedures of briefing and sensitizing everyone involved (entrepreneurs, employees and guests) to the environmental policy followed by each business (fεκ 2763, 2014). as a result of the above, tourist businesses that would choose to apply directional interventions would enjoy reduced operating costs by adopting a system of ecological operation and certification, they would correspond to the increasing global trend for more ecological forms of tourism and would contribute to the protection of the environment (fεκ 2763,2014). each business’s investment project had to involve part of the eligible actions defined in the programme, which followed five directions: _ energy saving by improving energy efficiency of premises and using renewable sources of energy (r.s.e.) _ water saving by installing appropriate systems and applications _ management of solid and liquid waste by incorporating appropriate technology applications and adopting a proper policy. _ development of ecological systems of management and certification of businesses for their implementation _ briefing and promotion of each business’s environmental policy as well as the green interventions it has made. following the submission of the investment projects and the approval of businesses that would be given a subsidy amounting to 45% of the investment cost, there was a time limit of twenty-four (24) months to make and present the interventions (fεκ 2763, 2014). for the coordination, management and implementation of the programme’s actions, the “intermediary authority of competitiveness and entrepreneurship business project” was created (fεκ β’ 1690/2010 and fεκ 352 β/19-2-13), named with the abbreviation εfepae. according to unpublished data obtained from efepae, exclusively for the requirements of this study, there were two hundred and thirty-six (236) businesses approved nationwide, most of which are located in crete (51), central macedonia (39), south aegean (32), thessaly (18), attica (18) and the ionian islands (16). the interest shown by each one of the above districts in upgrading its hotel force perhaps can be correlated with the number of visitors (demand) they have during the summer and the occupancy findings journal of sustainable architecture and civil engineering 2020/1/26 40 of beds they display. according to a study by the hellenic statistical authority -elstat (map 2a), the highest rate of bed occupancy in hotel accommodation took place in crete in 2017, followed by the ionian islands (63,7%), south aegean (62%), attica (50,5%) and central macedonia (49,1%). the island of crete as well as the southern aegean area belongs to the hottest climate zone of greece as described in map 2, meaning that there is a great demand for cooling a/c systems during the summer, which results in high energy consumption. map 2 greek climate zones (mitsopoulos, bellos and tzivanidis, 2018), bed occupancy on hotel accommodation per district, in greece elstat,2017) the interest shown by each one of the above districts in upgrading its hotel force perhaps can be correlated with the number of visitors (demand) they have during the summer and the occupancy of beds they display. according to a study by the hellenic statistical authority -elstat (map 2a), the highest rate of bed occupancy in hotel accommodation took place in crete in 2017, followed by the ionian islands (63,7%), south aegean (62%), attica (50,5%) and central macedonia (49,1%). the island of crete as well as the southern aegean area belongs to the hottest climate zone of greece as described in map 2, meaning that there is a great demand for cooling a/c systems during the summer, which results in high energy consumption. map 2 and 2a: greek climate zones (mitsopoulos, bellos and tzivanidis, 2018), bed occupancy on hotel accommodation per district, in greece elstat,2017) graph 3: percentage of hotels participating in the programme categorized according to the climate zone, authors’ work graph 3 percentage of hotels participating in the programme categorized according to the climate zone, authors’ work the interest shown by each one of the above districts in upgrading its hotel force perhaps can be correlated with the number of visitors (demand) they have during the summer and the occupancy of beds they display. according to a study by the hellenic statistical authority -elstat (map 2a), the highest rate of bed occupancy in hotel accommodation took place in crete in 2017, followed by the ionian islands (63,7%), south aegean (62%), attica (50,5%) and central macedonia (49,1%). the island of crete as well as the southern aegean area belongs to the hottest climate zone of greece as described in map 2, meaning that there is a great demand for cooling a/c systems during the summer, which results in high energy consumption. map 2 and 2a: greek climate zones (mitsopoulos, bellos and tzivanidis, 2018), bed occupancy on hotel accommodation per district, in greece elstat,2017) graph 3: percentage of hotels participating in the programme categorized according to the climate zone, authors’ work 41 journal of sustainable architecture and civil engineering 2020/1/26 chart 4 percentage of the 5 proposed directions chosen by enterprises in each region (source: data form the ministry of finance _ authors’ work) of the five directions proposed by the programme, the one preferred the most was category 1: “energy efficiency upgrade and utilization of renewable sources of energy (r.s.e.) with the aim of saving energy” (chart 5). in the context of this category, businesses had to do some (or all) of the following actions (fεκ 2763, 2014): 1. energy upgrade of the building shell 2. interventions for saving energy at the e/m facilities of the building and all other facilities 3. upgrading the system of natural/artificial lighting 4. replacement of electricity or other conventional fuels with natural or liquid gas 5. installation of a system for a joint production of heat and electricity 6. utilization of rse for the production of heating/cooling or electricity 7. installation of a system for energy management (bems) the energy efficiency upgrade by utilizing gdb showed the highest percentage of choice (31,88%) among businesses in total, obviously with the relevant interventions in the building shell and electrical and mechanical system facilities (chart 5). this particular decision made by the hoteliers is undoubtedly related to the assessment criteria of the programme, taking into consideration the fact that those whose investment plan aimed at saving primary energy, achieved the highest scores as depicted in table 6. this decision increased their chances of eligibility and potential to receive a subsidy of up to 100% of the budget for certain tasks (fεκ 2763, 2014). together with the incentives for business ranking, we reckon that the high percentage of the above eligible expenses are to do with the immediate and, at the same time, permanent benefits resulting from these interventions, as they involve upgrading and renovating the existing buildings/building facilities as well as reducing operating costs of the business as a result of the reduction of energy consumption. consequently, business owners moved primarily in this direction while aiming at recuperating their investment the quickest possible (it emerges from the reduction of operating costs), maximizing their profit and upgrading their property, which results in the property’s added value being increased. in the second and third place of preference, was the of the hotels selected to receive subsidies, only one hundred and two (102) managed to complete the project, most of which, as shown on chart 4 are located in crete, central macedonia and south aegean. of the hotels selected to receive subsidies, only one hundred and two (102) managed to complete the project, most of which, as shown on chart 4 are located in crete, central macedonia and south aegean. chart 4: percentage of the 5 proposed directions chosen by enterprises in each region (source: data form the ministry of finance _ authors’ work) of the five directions proposed by the programme, the one preferred the most was category 1: “energy efficiency upgrade and utilization of renewable sources of energy (r.s.e.) with the aim of saving energy” (chart 5). in the context of this category, businesses had to do some (or all) of the following actions (fεκ 2763, 2014): 1. energy upgrade of the building shell 2. interventions for saving energy at the e/m facilities of the building and all other facilities 3. upgrading the system of natural/artificial lighting 4. replacement of electricity or other conventional fuels with natural or liquid gas 5. installation of a system for a joint production of heat and electricity 6. utilization of rse for the production of heating/cooling or electricity 7. installation of a system for energy management (bems) the energy efficiency upgrade by utilizing gdb showed the highest percentage of choice (31,88%) among businesses in total, obviously with the relevant interventions in the building shell and electrical and mechanical system facilities (chart 5). journal of sustainable architecture and civil engineering 2020/1/26 42 development of green policies/procedures, integration of standards and the development and application of water saving systems (20,85% and 19,40% respectively) (chart 5). these choices can be justified by the particularly favorable rating awarded by the programme for certification on the basis of certain standards primarily as well as for the reduction of water supply in the process (table 6). chart 5 percentage of the 5 proposed directions chosen by enterprises in each region (source: data form the ministry of finance _ authors’ work) chart 5: percentage of the 5 proposed directions chosen by enterprises in each region (source: data form the ministry of finance _ authors’ work) this particular decision made by the hoteliers is undoubtedly related to the assessment criteria of the programme, taking into consideration the fact that those whose investment plan aimed at saving primary energy, achieved the highest scores as depicted in table 6. this decision increased their chances of eligibility and potential to receive a subsidy of up to 100% of the budget for certain tasks (fεκ 2763, 2014). together with the incentives for business ranking, we reckon that the high percentage of the above eligible expenses are to do with the immediate and, at the same time, permanent benefits resulting from these interventions, as they involve upgrading and renovating the existing buildings/building facilities as well as reducing operating costs of the business as a result of the reduction of energy consumption. consequently, business owners moved primarily in this direction while aiming at recuperating their investment the quickest possible (it emerges from the reduction of operating costs), maximizing their profit and upgrading their property, which results in the property’s added value being increased. in the second and third place of preference, was the development of green policies/procedures, integration of standards and the development and application of water saving systems (20,85% and 19,40% respectively) (chart 5). these choices can be justified by the particularly favorable rating awarded by the programme for certification on the basis of certain standards primarily as well as for the reduction of water supply in the process (table 6). assessment criteria score of businesses not required to keep accounts score of businesses keeping accounts development of environmental standards certification with iso 1400 or emas or easy emas and with ecolabel 22 22 certification only with emas/ easy emas 18 18 certification only with iso 1400 or with ecolabel 16 16 primary energy saving and environmental criteria primary energy saving (pes%) 20 15 reduction of water consumption (from public water network) (rwc %) 15 12 reduction of carbon dioxide emissions (rcde %) 15 12 reduction of litter/waste volume (rlwv) 13 10 reduction of water consumption (from public water network) (rwc %) 15 12 reduction of carbon dioxide emissions (rcde %) 15 12 reduction of litter/waste volume (rlwv) 13 10 table criteria of assessment and scores of businesses for green tourism program (source fεκ 2763, 2014_ authors’ work) 43 journal of sustainable architecture and civil engineering 2020/1/26 analysing the selected interventions, it emerges that hotel owners preferred to make drastic changes that concerned upgrading only the building shell. this approach is associated with the fact that such a choice upgrades their property both in terms of energy and aesthetics and results in an immediate reduction of operating costs. this means a quick recuperation of the investments and an increase in the value of the property. regarding the remaining categories that concerned water saving and waste management, fewer drastic interventions were selected by simply acquiring new equipment/machinery that would save water and contribute to waste management respectively. possible reasons for deciding on these interventions could be the following: 1. a lack of awareness among hotel owners regarding new technologies and a possible lack of expertise among the suppliers/installers responsible. the people in charge of each accommodation building opted for familiar and easy interventions without searching for innovative systems to which local installers may not be accustomed and which might have an increased cost of supply and installation in greece. 2. the desire to avoid extensive intervention to the building, which could involve a long period of the hotel being out of service. here, we ought to take into account that some districts, i.e. attica, have an increased number of tourists visiting all year round, not only during the summer season as it happens with the islands. in addition, extensive intervention regarding the buildings in the historical center of athens requires approval by many authorities and services, which in many cases is impossible due to legal issues or construction impediments (e.g. buildings protected by law, old structures in which extensive interventions are not possible, etc). 3. owners’ low environmental awareness, which leads them to more superficial interventions owing to a more immediate financial effect and profit for them. potentially, hotel owners’ interest may not be the very reason for the existence of the project, which is the protection of the environment, the reduction of pollutants emitted, sustainability etc, but the partial co-financed upgrade of their property with a simultaneous reduction of expenses. as for the area of attica, ten hotels managed to complete the suggested interventions. according to field work, the majority of hotels that took part in the green tourism program have given emphasis on the reduction of the electrical power consumption. only two focused on water saving strategies. for the reduction of the electrical energy consumption most of the hotels upgraded their cooling-heating system with the help of geothermal techniques or/and replacement of outdated machinery. two of them applied natural gas system combined with solar panels for warm water supply. only one hotel has made interventions on the building shell so as to improve not only the energy efficiency of the building but also its aesthetic value (table 7). moreover, only one hotel replaced all the old light bulbs with new that contribute to energy saving. regarding the strategies for water consumption, one hotel used special filters for water saving replacing all the old equipment (table 7). furthermore, all of the hotels described the interventions as beneficial for the hotel’s function, mentioning that this might have contributed to a slight increase in tourists’ preference. according to the field work conducted in the area of attica, the reduction of energy consumption varied between 12 and 40%. the 40% was achieved by only one hotel that implemented a radical geothermal technique. the percentage of the water saving was rather low, varied from 10 to 20%. as for the capital amortization, only three hotels managed to gain profit from the investment, succeeding in amortizing their investment by 20-40%. all the other hotels that took part in the research present low percentage of capital amortization. according to the interviews, bureaucracy is the key-obstacle. in addition, small family businesses do not seem to benefit from this type of programme since they use their own financial resources rather than conglomerate funding. as a consequence, the majority of hotels proposed larger amount of allowance as a critical factor for further development. discussion journal of sustainable architecture and civil engineering 2020/1/26 44 concluding with the intention of creating a “toolkit” of ways to save energy in hotels in greece, we suggest the following steps and actions: _ energy inspection/issuing c.e.u. according to kenak: the first step which will reveal the problems and energy consuming procedures of a hotel is the conduction of energy inspection by an eligible inspector. during an energy inspection, there must be proposed ways of improving the condition outlined and an action plan must be determined in conjunction with the owner, where the targets and priorities of interventions will be illustrated, always with a relation between cost-benefit in mind, defining the time period of the investment being recuperated. _ interventions of energy upgrading. subsequently, all the interventions determined during energy inspection must be carried out, with a view to reducing hotel energy consumption and the greenhouse gases produced. _ a second energy upgrade, where the new rank of the building will be defined and the current energy ranking will be illustrated. the areas where energy can be saved in an existing hotel is cooling/heating the interior spaces, producing warm water supply and warming pool water (in case there is a heated pool), lighting, electrical appliances used and waste management. at the same time, raising guest and staff awareness of the environmentally friendly policy of the accommodation plays an important role further supporting the effort (i.e. not washing room towels daily) (parpairi, 2016) and reducing possible waste owing to each guest’s different sense of thermal comfort when given the option of regulating the room’s cooling/heating systems manually. the best way in which a hotel could adopt a bioclimatic behaviour is by integrating r.s.e (heating solar system, photovoltaic panels, table 7 data selected through field work regarding the interventions made with the help of the programme green tourism in hotels located at the metropolitan area of attica, the capital of greece. the names of the hotels are not mentioned so as to provide anonymity to the participant of the qualitative research. (authors’ work) hotels category according ot stars number of rooms number of beds interventions hotel 1 4 80 144 1. a/c for the whole building 2. external elevator for people with disabilities 3. natural gas for hot water supply 4. automatic watering at all balconies that have plants 5. electric lightbulbs for energy saving 6. special filters for water saving in all the wash-basins 7. informative leaflets in the rooms that describe the interventions 8. new photocopy machines that save energy hotel 2 4 25 77 1. thermal façade systems 2. (a/c) inverter 3. low energy consumption tvs 4. new low energy consumption refrigerators hotel 3 no data available no data available 1. interventions for energy saving 2. water saving systems hotel 4 4 38 78 1. solar panels for hot water supply hotel 5 4 142 252 1. geothermal energy systems conclusions 45 journal of sustainable architecture and civil engineering 2020/1/26 wind turbines) (maroulas, 2011) for the production of electricity and heating. regarding lighting, although there was not relevant legislation up until recently, european guidelines are now followed in order to define energy efficiency of light systems, namely the amount of light (lumen) produced by a certain quantity of energy (watt) (ibid). despite the efforts made across europe for a sustainable development of the tourist industry through european guidelines and co-financed projects, like espa (i.e. green tourism), in greece there is no relevant legislation yet to assess hotels on the basis of environmental criteria (vasilatou, 2013). assessment of accommodation as well as its classification by way of stars is usually carried out with quantitative criteria (size, beds, facilities, etc) and not qualitative ones regarding their environmental awareness (ibid). at the same time, for all interventions conducted by means of the “green tourism” programme (apart from the three examples published on the project’s web page) there are no quantitative data to prove the tangible upgrade of accommodation as well as the water and energy saving. in addition to this, hotels completing the procedure of upgrading through the green tourism programme are very few in comparison with the number of the existing tourist accommodation businesses in greece. another crucial matter concerns the fact that the hellenic statistical authority does not have data regarding emissions of greenhouse gases categorized by the type of tourist accommodation nationwide. according to all this, the green tourism project may have been the most important policy for the improvement of energy efficiency of tourist accommodation in greece; however, there are many steps to be taken until there is a considerable decrease in the environmental impact tourist activities have on countries like greece, where tourism is an essential part of the economy. acknowledgment the authors would like to thank the ministry of finance of greece and the intermediary authority εfepae for providing unpublished data for the requirements of this study. alexandri, ε. (2012). sustainable design. patra: university of patra_school of architecture. becken, susanne & frampton, chris & simmons, david. (2001). energy consumption patterns in the accommodation sector the new zealand case. ecological economics. 39. 371-386. https:// doi.org/10.1016/s0921-8009(01)00229-4 coastlearn. (n.d.). retrieved february 2, 2019 from http://www.coastlearn.org/tourism/why_problems. html commission directive 91 (2002).energy efficiency of buildings european directive 31 (2010). energy performance of buildings farrou, i. (2013). investigation of energy performance and climate change adaptation strategies of hotels in greece. london: brunel university. fek 1690 b (2010). assignment of responsibilities for the programs “green tourism” and “ alternative tourism “ to efepae. athens: newspaper of the government fek 117 a (2016). framework for the establishment of private investment aid schemes for regional and economic development. athens: newspaper of the government fek 2367 b’ (2014). amendment of the implementation guide of the program “green tourism” athens: newspaper of the government fek 2763 b’ (2017). new kenak (building energy efficiency regulation). athens: newspaper of the government fek 352 b’ (2013). amendment of the assignment of responsibilities for the programs “green tourism” and “ alternative tourism “ to efepae. athens: newspaper of the government fek 407 b’ (2010). approval of building energy efficiency regulation. athens: newspaper of the government fek 5447/b (2018). approval of national plan to increase the number of buildings with near-zero energy consumption. athens: newspaper of the government georgarakis, ν., georgiou, π., lampropoulou, μ. (2017). evaluation and policy proposals for energy. athens: national center of social research references https://doi.org/10.1016/s0921-8009(01)00229-4 https://doi.org/10.1016/s0921-8009(01)00229-4 journal of sustainable architecture and civil engineering 2020/1/26 46 ghaitidak, d., & yadav, k. (2013, february 10). characteristics and treatment of greywater-a review. environmental science and pollution research, p. 2795. https://doi.org/10.1007/s11356-013-1533-0 greek law 3661 (2008). measures to reduce energy consumption of buildings and other provisions. athens: newspaper of the government greek law 4122 (2013). energy performance of buildings harmonization with directive 2010/31 / eu of the european parliament and other provisions. athens: newspaper of the government kya (joint ministerial decision) (2010). approval of building energy efficiency regulation. athens: newspaper of the government maleviti, e., mulugetta, y., & wehrmeyer, w. (2011, december 1). energy consumption and attitudes for the promotion of sustainability in buildings-the case of hotels. international journal of energy sector management, pp. 213-227. https://doi. org/10.1108/17506221211242077 maroulas, b. (2011). renewable energy sources. in v. maroulas, v. malakasis, d. bikas, s. keidou, & s. spyropoulou, energy planning guide bioclimatic architecture and energy saving (pp. 105-125). thessaloniki: ktirio magazine. mitsopoulos, g., bellos , e.,tzivanidis, c. (2018).financial and energetic optimization of greek buildings insulation. designs magazine,volume 2,issue 3. https://doi.org/10.3390/designs2030034 musall, e., weiss, t., voss, k., lenoir, a., donn, m., cory, s., & garde, f. (2010). http://www.enob.info/ fileadmin/media/projektbilder/enob/thema_nullenergie/eurosun_conference_graz_2010_net_ zero_energy_solar_buildingsx.pdf. retrieved from http://www.enob.info nezeh. (2016, march 5). http:// www.nezeh.eu /assets/media/pdf/ d2449.7%20position%20paper_ gr_en .pdf. retrieved from nezeh: www.nezeh.eu oikonomidou, μ., atanasiu, b., despret, c., maio, j., nolte, i., & rapf, o. (2011). europes buildings under the microscope. bpie. parpairi, κ. (2016). sustainability and energy use in small scale greek hotels: energy saving strategies and environmental policies. sbe16thessaloniki. thessaloniki. https://doi.org/10.1016/j.proenv.2017.03.099 unfccc. (n.d.). unfccc. retrieved february 28, 2019, from status of ratification of the convention: https://unfccc.int/process/the-convention/ w h a t i s t h e c o n ve n t i o n / s t a t u s o f ra t i f i c a t i on-of-the-convention water footprint network. (2017, ιανουάριος 18). http://waterfootprint.org/en/water-footprint/business-water-footprint/. retrieved from water footprint network: www.waterfootprint.org wttc. (2016). https://www.wttc.org/-/media/ files/reports/economic-impact-research/countries-2016/greece2016.pdf. retrieved from wttc: https://www.wttc.org vasilatou, h. (2013) eco-friendly hotel business in greece. peiraus:university of peiraus υpεκα. (2019). hellenic ministry of environment and energy. retrieved february 25, 2019, from http://www.ypeka.gr/default.aspx?tabid chara orfanoudaki architect, post-graduate student environmental design, school of science and technology, hellenic open university main research area architect engineer, sustainable design of buildings. address parodos aristotelous 18,26335, patra, greece e-mail: chara.orfan@labarch.gr tousi evgenia dr. architect-urban and regional planner, adjunct academic staff environmental design, school of science and technology, hellenic open university main research area environmental design of cities and buildings. address parodos aristotelous 18,26335, patra, greece e-mail: etousi@uniwa.gr about the authors https://doi.org/10.1007/s11356-013-1533-0 https://doi.org/10.1108/17506221211242077 https://doi.org/10.1108/17506221211242077 https://doi.org/10.3390/designs2030034 https://doi.org/10.1016/j.proenv.2017.03.099 https://doi.org/10.1016/j.proenv.2017.03.099 mailto:e-mail:chara.orfan@labarch.gr mailto:etousi@uniwa.gr journal of sustainable architecture and civil engineering 2023/1/32 186 theoretical evaluation of structural insulated panel walls in baltic climatic conditions received 2022/12/14 accepted after revision 2023/04/17 theoretical evaluation of structural insulated panel walls in baltic climatic conditions jsace 1/32 anatolijs borodinecs*, vladislavs jacnevs riga technical university, faculty of civil engineering, department of heat engineering and technology, kipsalas st. 6a, lv-1048, riga, latvia *corresponding author: anatolijs.borodinecs@rtu.lv https://doi.org/10.5755/j01.sace.32.1.32982 journal of sustainable architecture and civil engineering vol. 1 / no. 32 / 2023 pp. 186-195 doi 10.5755/j01.sace.32.1.32982 abstract introduction the reduction of construction costs as needed to increase construction productivity forces to the introduction of alternative construction solutions. thus, the share of structural insulated panels for single-family houses is increasing. despite the fact it is a widely used technology in the usa, there is a significant information gap for safe application in baltic climatic conditions. the dynamic hygrothermal simulations delphin was used to evaluate risks of mold growth and interstitial condensation. the city of riga was selected to evaluate the hydrothermal performance of sip panels. the different indoor air parameters were considered for in-depth evaluation. it was found that there is no harmful interstitial condensation and mold risk stayed at a relatively low level. however, wall orientation plays a significant role in whole year moisture accumulation dynamic. keywords: sip, deplphin, hydrothermal performance, interstitial condensation. structural insulated panel (sip) is a composite building material which consists of three main layers: one core layer and two skin layers. usually a thicker core layer is made of non-structural materials, such as extruded and expanded polystyrene (xps/eps), as well as polyurethanes (pur) (panjehpour et al., 2013). however, more specific materials could be found in different sips. for instance, in scs (steel-concrete-steel) sip a lightweight/normal concrete is used (mugahed amran et al., 2020), while for a skin layer production cement, plywood, sheet metal or oriented strand board (osb) may be chosen. these layers are connected to each other by dint of an adhesive (ahmad kayello, 2018). first introduced in north america and being quite new, this material has not yet gained a widespread recognition around the world, due to a firmly ingrained approach in housing sector in the form of timber-framed construction in current building industry. however, this is gradually changing as there is a tendency to invest in innovative solutions in order to overcome modern day challenges, and these changes make sips more in demand today (harris et al., 2019). sips are utilized in the construction of floors, external walls, ceilings etc., where the thickness of the insulation differs according to the needed thermal insulation value. panels can be produced in large units with prefabricated openings for windows and doors. then these large-sized elements are ready to be delivered directly to the construction site (švajlenka & kozlovská, 2022). like any other building material, sip has its advantages and flaws. as it was mentioned earlier, sips are prefabricated structures, so they have advantages of controlled quality, reduced material losses, fast construction, less required labour and, consequently, lower total costs (panjehpour et al., 2013). furthermore, more classic structural insulated panels (osb-insulation-osb) are lightweight and have great energy performance characteristics (phillips et al., 2021). some of the flaws 187 journal of sustainable architecture and civil engineering 2023/1/32 of sip panels are as follows: a core is usually made from a non-eco-friendly artificial material, which under normal conditions is rather flammable; panels are air-impermeable, so indoor environment might be exposed to risk of high humidity level; sips do not have a high load-bearing capacity, therefore it is necessary to ensure a reinforcement against different kinds of loads (mohammadabadi et al., 2021). it is evaluated that water and the subsequent accumulation of moisture in building structure is the cause of approximately three-quarters of all building damages. thus, the management of water in buildings is one of the most important factors affecting a building service life. there are four main mechanisms of moisture transport in buildings: vapour diffusion, air movement, capillary suction, and fluid flow (bastien & winther-gaasvig, 2018). the transfer of water vapour by diffusion, which is primarily considered in scope of this paper, occurs when the difference in vapour pressure between two sides of a building structure takes place. the common practice to prevent vapour diffusion in cold climate is to add vapour barrier (or retarder) on the interior side of the insulation (cammalleri et al., 2003). it can be stated that unlike sip walls, performance of widely used timber frame walls regarding a water vapour diffusion was largely investigated during past years. numerous studies were carried out in temperate maritime climates using perspective renewable hemp-based insulation materials (latif et al., 2014), (latif et al., 2015). after experiments conducted in more severe climate regions, a group of estonian researchers suggested that a wind barrier plays a crucial role in terms of condensation and mould growth risk inside a wall structure (pihelo et al., 2016), (pihelo & kalamees, 2016). obtaining similar results, geving et all. observed no significant difference in relative humidity levels when installing vapour barriers with high (sd = 40 m) and low (sd = 2 m) water vapour resistance, however this requires thick (50 mm) layer of wind barrier made of wood fibre board (geving et al., 2015). finally, morelli et all. came to a conclusion that generally cellulose insulation showed lower relative humidity levels than mineral wool insulation, however, depending on internal humidity classes possible safe solution for wind-vapour barrier ratio varies from 1:10 to 1:1.5 (morelli et al., 2021). several studies have been conducted considering sip-based huts exposed to canadian artic climate. the primary focus of these studies was the examination of attics and various sip joints in terms of airtightness and hygrothermal performance. it has been examined that the weakest point occurred at the joint of 3 building envelope structures meet each other (for example, two aligned wall structures and a ceiling structure). moreover, a large air leakage through such joints, where a structure highly relies on a tape seal, could be reduced intending to avoid possible condensation, snow, and frost accumulation (a kayello et al., 2013), (ahmad kayello et al., 2017). although most often sip building failures are related to rainwater penetration into an enclosure or warm air leakage from interior space structure, there is a hypothesis which states that under cold climate conditions wall siding could act as a vapour retarder and could initiate damaging condensation. an example of such situation was noticed in sip walls with vinyl siding in alaska (trechsel et al., 2010). so-called glaser method, a steady-state condition principle for a prediction of a maximum interstitial condensation and annual moisture balance, is often being practiced in latvia. nevertheless, it is considered as an assessment method rather than precise data interpretation, that does not provide highly accurate results (bsi, 2012). the aim of this study is to apply a dynamic hygrothermal simulation approach to evaluate the reliability of utilizing a conventional wall structure in latvian climate. the main limitation of this study is absence on national data on wind driven rain. data from meteonorm was used for calculations. despite the fact that many study addressed hydrothermal performance of sip panels, there is a lack of data on such construction behavior in baltic climatic conditions. the practical significance of this study is data for energy auditors journal of sustainable architecture and civil engineering 2023/1/32 188 and engineers on sustainability of such construction. also, study addressed evlauation of hydrothermal performances based on real measurements in bathrooms. however measurements and simulation took place for the total duration of the simulation was 19 days, this brings initial information on possible risk. fig. 1 outdoor climate data methods to achieve the determined goal, further dynamic hygrothermal simulations were executed in delphin 6.1 software. delphin is designed to simulate the combined transport of heat, air, moisture, and other penetrable matter in porous building materials. this tool is widely used in scientific community and has been validated by many researchers in their recent works (claude et al., 2019), (fantucci et al., 2017), (pihelo et al., 2020), (wang & ge, 2018). unfortunately, it is challenging to acquire all necessary climate data for latvian cities, so the outdoor climate data for the simulation of the wall in the city of riga was obtained from meteonorm 8.1.1 software, taking into account ambient temperature, relative humidity, wind driven rain, short wave solar radiation and sky radiation (see fig. 1). with a purpose to check data from meteonorm, it was decided to gather data from a local weather station as well. as it can be seen in fig. 2, monthly average temperature values from meteonorm calculated from a period of 2000-2019 were in a good agreement with the graph plotted using values from the local station. this information was found to be reliable for subsequent usage. -5 0 5 10 15 20 25 ja n fe b m ar ap r m ay ju n ju l au g se p oc t no v de c te m pe ra tu re , o c meteonorm (2000-2019) local station (2009-2021) fig. 2 comparison of average month temperature values for riga 189 journal of sustainable architecture and civil engineering 2023/1/32 30 50 70 90 110 1 10 19r el at iv e hu m id ity , % day 18 20 22 24 26 1 10 19 te m pe ra tu re , o c day table 1 properties of simulated materials a wall selected for a hygrothermal analysis is not yet a very commonly applied solution for a single-family dwelling in latvia, therefore there is a lack of experience related to performance of such a structure in the local environment. the examined wall has sip-based structure (see fig. 3) and it consists of 11-mm osb, 180-mm eps insulation layer, another 11-mm osb, wind barrier (sd = 0.02 m) and 12.5-mm cement board. some used material properties can be found in table 1, however, the wind barrier is excluded from the simulation as a material layer and appears only as an additional equivalent of air layer thickness (sd) between external osb and cement board. delphin id material bulk density, kg/m3 thermal conductivity, w/(m*k) water vapour diffusion resistance factor, water uptake coefficient, kg/(m2*s0.5) 650 osb 595.0 0.130 165 0.002 187 expanded polystyrene board 23.0 0.036 96 0.00001 654 cement board 1158.7 0.313 26.4 0.014 inclination of simulated wall is 90°, orientation is 0° (north-facing wall). initial temperature was set to 20°c, and relative humidity to 80 %. fig. 3 studied sip wall fig. 4 measured boundary condition data for the bathroom simulation the experiments were made in two different climates. in the beginning, the indoor climate was chosen to be calculated, based on input weather data, according to din en 15026 and wta leaflet 6.2 for increased moisture load. the range of temperature during a year is 20–25°c, the range of relative humidity levels is 35-65 %, the overall simulation lasted 3 full years. then real measured values (specifically temperature and relative humidity, which have higher values than in the prior climate data set) from the bathroom of the apartments located in riga were set as indoor boundary conditions. data acquisition was executed using hobo u12-013 data loggers from 10-th to 28-th of november with 5-minutes intervals (see fig. 4). the total duration of the simulation was 19 days. (a) (b) journal of sustainable architecture and civil engineering 2023/1/32 190 since osb is a wood-based building material, which is especially susceptible to mould and moisture damages, three 1-mm thick layers of osb in the above-mentioned simulations were monitored: (a) layer just before eps (closer to the inner surface), (b) layer just after eps (closer to outer surface), (c) layer before wind barrier. to evaluate the risk of mould growth inside the selected wall structure, the so-called vtt model, which is implemented in delphin, is suitable. the original vtt model was created in finland by hukka and vittanen (hukka & viitanen, 1999) and gained an extensive recognition over the years. to perform an assessment, it is necessary to set relative humidity, temperature, and specific parameters related to examined material structure. as an output, the mould index is obtained (mi, ranges from 0 to 6, that means no growth and 100 % coverage of the surface, respectively), which represents the damage of materials by mould (fantucci et al., 2017). an interpretation and evaluation of mould growth risk based on mould index offers a traffic light classification: if no risk is presented, the traffic light remains green. this classification applies to interfaces which are not in direct contact with the inside air for mi<2 (several local mould growth colonies on surface (microscope)) that was chosen as the evaluation criterium to stay on the safe side (viitanen et al., 2015). regarding the parameters needed to be determined, it was fairly noticed that mostly unclear and ambiguous suggestions exist so far (johansson et al., 2021). for this purpose, default values from wufi mold index vtt add-on for osb were used – for this reason material type and surface type were selected to be “sensitive” to mould growth, while mould growth decline rate was set as “almost no decline”. results and discussion fig. 5 demonstrates that no condensation occurred at any time of the simulation in every controlled layer as the relative humidity level did not exceed 95 %, which is a threshold for over hygroscopic moisture defined in delphin. layers (b) and (c) have similar profiles, yet more pronounced fig. 5 temperature and relative humidity inside examined wall within 3 years, (a) layer before eps, (b) layer after eps, (c) layer before wind barrier (a) (b) (c) 191 journal of sustainable architecture and civil engineering 2023/1/32 relative humidity fluctuations characterize (c) layer since it is located closer to outer surface and is exposed to outdoor climate. fig. 6 presents a comparison of modelling results where the two earlier defined climates were applied. the corresponding graphs of (b) and (c) layer have a quite minor diversity in both parameters. despite this, outcome in (a) layer for bathroom climate shows greater temperatures during the whole period of simulation (that distinguishes the mentioned climate data set) and slightly higher relative humidity levels, which at the same time do not exceed 1.5 % limit, so it can be stated that in this particular situation indoor data set with increased temperature and moisture load has relatively little impact on the wall’s hygrothermal performance. fig. 6 temperature and relative humidity inside examined wall from 10th to 28-th of november: outdoor climate – din en 15026 and wta 6.2 (left), outdoor climate – measured data (right), (a) layer before eps, (b) layer after eps, (c) layer before wind barrier (a) (b) (c) journal of sustainable architecture and civil engineering 2023/1/32 192 fig. 7 relative humidity profile of the examined wall (coordinate 0 m displays the outdoor surface), outdoor climate – din en 15026 and wta 6.2 (a), outdoor climate – measured data (b) fig. 8 vtt mould index of examined wall in (c) layer before wind barrier according to fig. 7, a shortterm increase in humidity and temperature inside a thermal envelope does not affect the operation quality of the structure. the relative humidity level increased insignificantly, while condensation took place only in the cement board regardless of the provided climate. although the mass density of condensed liquid water in the board has separate peaks during the years, the maximum reached values do not exceed 31.1 kg/m3 and all accumulated condensate dries out in a spring-summer period (outdoor climate din en 15026 and wta 6.2). as expected, the most critical osb layer with respect to possible mould growth is (c) layer (see fig. 8), where the peak mi value is only 0,31, which is far from described limit of 2. it is worth noting that the graph has a stable profile, which means that it has reached the maximum mi and will not rise in future, whilst mi in (a) and (b) layer tend to be even closer to 0, hence the wall structure is assumed to be completely mould safe. however, wall orientation plays an import role. as it can be seen from fig. 9, the south oriented wall has a better drying potential. fig. 9 presents interface between external osb and eps. in case of north wall relative humidity doesn’t drop below 60 %. (b) (a) 193 journal of sustainable architecture and civil engineering 2023/1/32 fig. 9 temperature and relative humidity for different wall orientation in the current study, simulations of sip wall and assessment of its hygrothermal performance in latvian climate conditions were conducted. results reveal that, in general, the wall appeared to be suitable for both investigated indoor climate cases. all the examined osb layers stayed below condensation limit, which is outreached only in the outdoor cement board layer, nonetheless, conclusions journal of sustainable architecture and civil engineering 2023/1/32 194 even there a condensate does not accumulate and evaporates freely throughout the year. the vtt mould model also shows that there is a small and harmless amount of expected mould. in addition, it was observed that increased temperature and relative humidity levels indoors do not largely affect these parameters inside the wall – the effect evidently falls towards the outdoor surface. in order to expand knowledge about the moisture damage resistance of sip walls, as well as other parts of a building enclosure, and about interaction with interior spaces of increased moisture and temperature loads, further investigation should be carried out. this should include models validated by real measured data that would represent an influence of a long-term operation under simulated extreme conditions. the sip panels could be recommended for application in baltic climatic conditions. however, some extra stimulation may be required in case of north oriented wall in combination with high internal moisture loads. for example, for such premises as sauna, small spa etc. also, ventilation plays an important role to minimalize risks of interstitial condensation and mould growth. future work will be focused on estimation of internal moisture loads in different type of rooms with a special focus on bathrooms. acknowledgment this work has been supported by the european regional development fund project ‘a new concept for low-energy eco-friendly house’, grant agreement no 1.1.1.1/19/a/017. this study has been carried out in collaboration with modular timber frame house manufacturer “wwl houses” ltd. bastien, d., & winther-gaasvig, m. (2018). influence of driving rain and vapour diffusion on the hygrothermal performance of a hygroscopic and permeable building envelope. energy, 164. https://doi. org/10.1016/j.energy.2018.07.195 bsi. (2012). iso 13788:2012 hygrothermal performance of building components and building elements internal surface temperature to avoid critical surface humidity and interstitial condensation calculation methods. building standard institute, 1. cammalleri, v., senior, a. i. a., manager, p., & gumpertz, s. (2003). condensation in the building envelope: expectations and realities. sspc 2003: the industrial protective coatings conference and exhibit, ernest n. morial convention center, new orleans, la, 26 29 october 2003. claude, s., ginestet, s., bonhomme, m., escadeillas, g., taylor, j., marincioni, v., korolija, i., & altamirano, h. 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(2022). efficient and sustainable wood-based constructions. in efficient and sustainable wood-based constructions. https://doi.org/10.1007/978-3-030-87575-6 trechsel, h. r., bomberg, m. t., & tsongas, g. (2010). case studies of moisture problems in residences. in moisture control in buildings: the key factor in mold prevention-2nd edition. https://doi. org/10.1520/mnl11553m. https://doi.org/10.1520/ mnl18-2nd-eb viitanen, h., krus, m., ojanen, t., eitner, v., & zirkelbach, d. (2015). mold risk classification based on comparative evaluation of two established growth models. energy procedia, 78. https://doi.org/10.1016/j.egypro.2015.11.165 wang, l., & ge, h. (2018). stochastic modelling of hygrothermal performance of highly insulated wood framed walls. building and environment, 146. https://doi.org/10.1016/j.buildenv.2018.09.032. https://doi.org/10.14305/ibpc.2018.ms-3.05 about the authors vladislavs jacnevs assistant department of heat engineering and technology, faculty of civil engineering main research area building physics, measurements of indoor air parameters address kipsalas str. 6a 533, riga, lv-1048, latvia e-mail: vladislavs.jacnevs@edu.rtu.lv this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). anatolijs bodinecs lead researcher department of heat engineering and technology, faculty of civil engineering main research area building physics, buildings energy efficiency, hvac energy performance address kipsalas str. 6a 539, riga, lv-1048, latvia e-mail: anatolijs.borodinecs@rtu.lv 49 journal of sustainable architecture and civil engineering 2021/2/29 *corresponding author: bemanian@modares.ac.ir investigation of the effects of applying social sustainability components on residential satisfaction received 2021/06/07 accepted after revision 2021/07/13 journal of sustainable architecture and civil engineering vol. 2 / no. 29 / 2021 pp. 49-61 doi 10.5755/j01.sace.29.2.29217 investigation of the eeffects of applying social sustainability components on residential satisfaction jsace 2/29 http://dx.doi.org/10.5755/j01.sace.29.2.29217 mohammadhossein azizibabani, mohammadreza bemanian*, mansour yeganeh faculty of art, tarbiat modares university, tehran, iran introduction today, decades after the emergence of the concept of sustainable development, the long-term positive effects of achieving sustainable development goals in all environmental, economic, and social dimensions on the quality of human life are undeniable. the purpose of this research is to explain the mechanism of effects of applying the social sustainability components on the level of residential satisfaction in the scale of residential complexes. the research uses a mixed (quantitative and qualitative) methodology in terms of the nature of the data and the research method is descriptive-analytical (causal and comparative). the conceptual model of the research, which includes the relationships between the variables of perceived quality of social sustainability components, residential desires associated with these components, perceived quality of housing architecture, and residential satisfaction, has been proposed based on the study of theoretical foundations through logical reasoning method. this model has been tested through obtained data from a questionnaire in a field study conducted in the baghe behesht residential complex in the saadatabad neighborhood of tehran. according to the results, the application of the components of social sustainability has a significant effect on residential satisfaction by improving the quality of housing architecture, and in conditions of qualitative deficiency in social sustainability components, residential desires associated with these components will reduce the perceived quality and the level of residential satisfaction. keywords: social sustainability, residential satisfaction, residential desires, perceived quality, residential complex. nowadays, moving towards achieving sustainable development goals in various fields, including architecture and urban planning, is known as a necessity than a choice. the application of the components of sustainable design in architecture is the main solution to achieve the goals of sustainable development in this field. in this regard, most of the conducted researches have focused on the environmental and economic dimensions of sustainability. the goals related to these two dimensions of this concept will be mainly achieved by conserving resources and energy and moving towards the use of renewable energies in the long term. in addition to finding a comprehensive solution for environmental and economic considerations, the main challenge of sustainable architecture is achieving an appropriate level of quality of life and preserving cultural and social values along with providing environmental comfort (kim, 1998). the second part of this challenge journal of sustainable architecture and civil engineering 2021/2/29 50 which is related to residential buildings is more important, and also is presented as a subset of social sustainability issues. social sustainability is based on the general view of the status of social justice for the present and future generations and adherence to its principles can affect activities related to the construction of residential environments. although the issue of energy and resource consumption in residential buildings, especially in developing countries, is important and this is related to environmental and economic goals of sustainability, but providing comfort and tranquility in residential environments is a vital point. it should be noted that achieving the desired goals should be in the short term or at the very beginning of the work cycle of residential buildings. in fact, this refers to the well-known definition of sustainable development, which was presented in the brundtland report as follows: development that meets the needs of the present without compromising the ability of future generations to meet their own needs (wced, 1987). therefore, improving the quality of life through environmental design is an issue that has been addressed as the concept of residential satisfaction. the concept of satisfaction refers to a wide range of desires to meet the basic or transcendent needs of human beings (rafieian, aminsalehi, & taghvaei, 2011) which are necessary to ensure human comfort and tranquility in residential environments. numerous factors including cultural, economic, household livelihoods, climatic conditions, and construction technologies affect the formation of housing and urban fabrics and housing has mutually a significant effect on the lifestyle and cultural pattern of residence. therefore, housing is considered beyond a basic need for human beings. in this regard, residential satisfaction is a concept based on the perception of space and depends on the quality of responding to a set of residential needs that are rooted in culture, lifestyle, geography and climate. in definition, residential satisfaction is the result of peoples’ understanding of the differences between their preferences and aspirations and standards and the actual housing conditions (campbell, converse, & rodgers, 1976). in other words, residential satisfaction is the result of the comparison between residential conditions and residential desires that several factors, including cultural, economic conditions and social status of residents play a role in this analogy. the environmental and economic effects of applying sustainability components in architecture are more tangible on large scales that may not affect the quality of human life directly. therefore, the present research has investigated the effects of the architectural application of social sustainability components on the level of residential satisfaction at the residential complexes scale. this research was carried out aimed to explain the mechanism of the relationship between the quality of social sustainability components in architecture and the level of residential satisfaction. in this regard, the following questions are raised: which components of social sustainability in architecture play a key role in improving the level of residential satisfaction? how is the mechanism of the effect of social sustainability components on the quality of housing architecture and residential satisfaction? this research uses a mixed (quantitative and qualitative) methodology in terms of the nature of the data and the research method is descriptive-analytical (causal and comparative). theoretical foundations and literature have been reviewed to identify the components and indicators of social sustainability in architecture, and residential satisfaction in the scale of the architectural quality of residential complexes. to extract the indicators related to the mentioned variables, the content analysis method has been used. in this regard, the content unit is sentences and words that were related to the variables. categories and subcategories have been extracted from the existing literature and then have been classified. the conceptual model of the research and relationships between the variables have been determined using the logical reasoning method. the conceptual model should be tested in an experimental study, so the baghe behesht residential complex in the research methodology 51 journal of sustainable architecture and civil engineering 2021/2/29 theoretical foundations saadatabad neighborhood of tehran city has been considered as a case study. the data related to the variables have been obtained through a questionnaire and the method of path analysis was used to verify the conceptual model. to answer the first research question, regression analysis on the collected data has been used to determine the key components of social sustainability in improving the level of residential satisfaction. in this analysis, the level of residential satisfaction has been considered as a dependent variable on the application of the components of social sustainability. concerning the second question, the conceptual model of the research has been evaluated through the amos-version 24 software. the concept of residential satisfaction studies on residential satisfaction can be divided into three categories based on the general view, objectives, and scope of research. according to the general view, a group of researchers investigated residential satisfaction as a criterion for determining the quality of the living environment (marans & rodgers, 1975; galster & hesser, 1981; cutter, 1982). the other researchers consider this concept as a predictor of the residents' behavior regarding residential mobility, improving housing status, or adaptation to the current situation (separe, 1974; premius, 1986). according to the objectives, researches on residential satisfaction are divided into three categories. some researchers have sought to determine the relationships between factors affecting residential satisfaction (garcia, 1994; amerigo & aragones, 1997; varady, preiser, & wolfgang, 1998; parkes, kearns, & atkinson, 2002; choudhury, 2005; fallahi, hariza, husniyah, & abdul rahim, 2015). some other researchers have focused on predicting residential satisfaction in residential environments (theodori, 2001; ogu, 2002). moreover, the third group of researchers has investigated settlements based on factors affecting residential satisfaction (lu, 1999; russell & james, 2008; azimi & esmaeilzadeh, 2017; azizibabani & bemanian, 2019). according to the scope, researches on residential satisfaction are divided into three categories. a group of researchers has investigated residential satisfaction at the scale of urban apartments to residential complexes (zabihi, habib, & rahbarimanesh, 2011; abbaszadeh, gohari, & askari rabori, 2017). another group has examined this concept at the neighborhood or urban scale (dekker, de vos, musterd, & van kempen, 2011; azemati, pourbagher, & rostami, 2017). moreover, another group has examined this concept on the scale of urban geography (theodori, 2001). the concept of residential satisfaction contains a wide range of studies, but most of them were empirical and haven't led to a theoretical model or theory. therefore, basic theoretical studies on the concept of residential satisfaction are listed in table 1. the concept of social sustainability the emergence of the concept of social sustainability coincided with the presentation of the brundtland report on various dimensions of sustainable development in 1987. in the beginning, the environmental dimension of sustainable development was more important compared to other dimensions, but over time the importance of all environmental, economic, and social dimensions was equal in development-related activities (colantonio & lane, 2007). the social dimension of sustainable development provides the context for strengthening social solidarity, increasing the level of social interactions, and creating equality for access to public facilities such as health, education, transportation, housing, etc (mckenzie, 2004). according to qanbari and farhadi (2017), the foundations of sustainable social development are equality (creating equal opportunities for all members of society), diversity (possibility of racial and cultural diversity), solidarity, quality of life (meeting basic needs and hierarchical needs), and democratic government. thin et al. (2002), introduce social justice, social solidarity, participation, and security as four criteria of sustainable social development. murphy (2012) concluded that the four main pillars of social sustainability are justice, participation, awareness for sustainability and social solidarity. weingaertner and moberg journal of sustainable architecture and civil engineering 2021/2/29 52 table 1 basic theoretical research on the concept of residential satisfactio title researcher description sociological theory of home adjustment (reimer, 1943) according to this theory, the variables that determine human residential needs change under the influence of two factors of time and type of household. residential mobility (rossi, 1955) according to this theory, residential mobility is defined as a natural part of every family life cycle. therefore, people change their place of residence to meet their residential needs that are affected by time. some of the most important factors affecting the change of residential needs and desires that have been discussed in the context of this theory are the number of family members, aging, and changing social status of the family. after the emergence of this theory, the concept of residential mobility was more investigated in the researches. migration as an adjustment to environmental stress (wolpert, 1966) wolpert believed that the hypotheses about economic, climatic, aesthetic, etc. factors regarding residential mobility are all minor factors and none of them can be considered as a determining criterion in the residential mobility behavior of residents. he believed that environmental stress is a determining factor in residents’ behavior regarding residential mobility in an urban environment, and some of the sub-factors of stress include heavy traffic, noise, light, air and water pollution, and lack of outdoor space. he developed an environmental model which showed the impact of these variables on the migration decision of residents. a theory of family housing adjustment (morris & winter, 1975) morris and winter provide a conceptual and theoretical framework for studying the behavior of households in adapting to a residential environment. according to their theory, each family evaluates its housing according to cultural and family norms and seeks to meet the normative housing deficits. residential mobility, relocation based on household needs, or adjustment of the family desires and needs based on current housing status are some of the measures that can be taken in this regard which may be done when restrictions prevail over behavioral patterns. a theory of the purposes of human life (marans & rodgers, 1975) marans & rodgers have presented a conceptual framework based on maslow's (1958) theory of the level of human needs to determine the quality of urban life in three spatial scales, which includes objective and subjective data. these three spatial scales include community (country-city), neighborhood, and private home. according to this theory, people's assessment of their satisfaction in the three mentioned scales depends on their personal characteristics and residential satisfaction in every scale affects the others. fig. 1. a broad model framework for investigating subjective assessment of determinants of satisfaction with the residential environment the concept of residential satisfaction contains a wide range of studies, but most of them were empirical and haven't led to a theoretical model or theory. therefore, basic theoretical studies on the concept of residential satisfaction are listed in table 1. table 1: basic theoretical research on the concept of residential satisfaction title researcher description sociological theory of home adjustment (reimer, 1943) according to this theory, the variables that determine human residential needs change under the influence of two factors of time and type of household. residential mobility (rossi, 1955) according to this theory, residential mobility is defined as a natural part of every family life cycle. therefore, people change their place of residence to meet their residential needs that are affected by time. some of the most important factors affecting the change of residential needs and desires that have been discussed in the context of this theory are the number of family members, aging, and changing social status of the family. after the emergence of this theory, the concept of residential mobility was more investigated in the researches. migration as an adjustment to environmental stress (wolpert, 1966) wolpert believed that the hypotheses about economic, climatic, aesthetic, etc. factors regarding residential mobility are all minor factors and none of them can be considered as a determining criterion in the residential mobility behavior of residents. he believed that environmental stress is a determining factor in residents’ behavior regarding residential mobility in an urban environment, and some of the sub-factors of stress include heavy traffic, noise, light, air and water pollution, and lack of outdoor space. he developed an environmental model which showed the impact of these variables on the migration decision of residents. a theory of family housing adjustment (morris & winter, 1975) morris and winter provide a conceptual and theoretical framework for studying the behavior of households in adapting to a residential environment. according to their theory, each family evaluates its housing according to cultural and family norms and seeks to meet the normative housing deficits. residential mobility, relocation based on household needs, or adjustment of the family desires and needs based on current housing status are some of the measures that can be taken in this regard which may be done when restrictions prevail over behavioral patterns. a theory of the purposes of human life (marans & rodgers, 1975) marans & rodgers have presented a conceptual framework based on maslow's (1958) theory of the level of human needs to determine the quality of urban life in three spatial scales, which includes objective and subjective data. these three spatial scales include community (country-city), neighborhood, and private home. according to this theory, people's assessment of their satisfaction in the three mentioned scales depends on their personal characteristics and residential satisfaction in every scale affects the others. figure 1: a broad model framework for investigating subjective assessment of determinants of satisfaction with the residential environment. source: (marans & rodgers, 1975) residential satisfaction theory (glaster, 1985) as the cognitive psychology trend grew, glaster developed a theory of residential satisfaction based on psychology. glaster describes the psychological structure of the concept of residential satisfaction as follows: source: (marans & rodgers, 1975) 53 journal of sustainable architecture and civil engineering 2021/2/29 title researcher description residential satisfaction theory (glaster, 1985) as the cognitive psychology trend grew, glaster developed a theory of residential satisfaction based on psychology. glaster describes the psychological structure of the concept of residential satisfaction as follows: each person's cognitive structure acts as a source of coping with life situations and leads to adaptation or incompatibility with living conditions. in this process, each person's mental schemas play a vital role as a benchmark. regarding housing, if people's perceptions of housing conditions meet or exceed their mental standards, residential satisfaction would be high. otherwise, people will resort to adaptive processes such as redefining their desires and needs and changing their assessment of the current housing conditions or will not be able to tolerate the current housing conditions and will make broad changes in housing or move to another place. glaster believes that the aspects of the living environment that have the greatest impact on the level of residential satisfaction do not necessarily determine the priority of residents in the improvement of the living environment. therefore, he introduces a new social index to assess the residential preferences of individuals under the title of “marginal residential improvement priority”. according to the psychological structure of this index, people consciously or unconsciously prioritize different aspects of the residential environment based on their preferences. according to the results of glaster’s field study, regardless of the dissatisfaction in which aspect of the living environment, people give the priority to improving the quality of the housing unit to improve the level of residential satisfaction. theoretical model of amerigo & aragones (amerigo & aragones, 1997) the approach of amerigo and aragones in the study of residential satisfaction is to provide a conceptual framework for studying the relationship between personal characteristics and the residential environment in providing residential satisfaction. their approach goes beyond providing a conceptual model of satisfaction, examines the interaction between the personal characteristics and the residential environment, and analyzes various cognitive, emotional, and behavioral interactions in the context of this relationship. according to this model, the objective attributes of the residential environment, when evaluated by the person, become subjective and bring a degree of satisfaction. thus, mental characteristics are influenced by the personal characteristics of individuals. each person's cognitive structure acts as a source of coping with life situations and leads to adaptation or incompatibility with living conditions. in this process, each person's mental schemas play a vital role as a benchmark. regarding housing, if people's perceptions of housing conditions meet or exceed their mental standards, residential satisfaction would be high. otherwise, people will resort to adaptive processes such as redefining their desires and needs and changing their assessment of the current housing conditions or will not be able to tolerate the current housing conditions and will make broad changes in housing or move to another place. glaster believes that the aspects of the living environment that have the greatest impact on the level of residential satisfaction do not necessarily determine the priority of residents in the improvement of the living environment. therefore, he introduces a new social index to assess the residential preferences of individuals under the title of “marginal residential improvement priority”. according to the psychological structure of this index, people consciously or unconsciously prioritize different aspects of the residential environment based on their preferences. according to the results of glaster’s field study, regardless of the dissatisfaction in which aspect of the living environment, people give the priority to improving the quality of the housing unit to improve the level of residential satisfaction. theoretical model of amerigo & aragones (amerigo & aragones, 1997) the approach of amerigo and aragones in the study of residential satisfaction is to provide a conceptual framework for studying the relationship between personal characteristics and the residential environment in providing residential satisfaction. their approach goes beyond providing a conceptual model of satisfaction, examines the interaction between the personal characteristics and the residential environment, and analyzes various cognitive, emotional, and behavioral interactions in the context of this relationship. according to this model, the objective attributes of the residential environment, when evaluated by the person, become subjective and bring a degree of satisfaction. thus, mental characteristics are influenced by the personal characteristics of individuals. figure 2: a systemic model of residential satisfaction. source: (amerigo & aragones, 1997) theoretical model of mccrea (mccrea, 2007) mccrea sought to find the relations between the objective dimensions of the urban environment and the mental evaluations based on them, as well as the effects of psychological processes and residential mobility on these relations. his findings indicate a weak correlation between the objective dimensions of the environment and the subjective assessments based on it. this indirect relation arises from the effect of people's comparative standards on their mental perception of the objective aspects of the environment. the concept of social sustainability the emergence of the concept of social sustainability coincided with the presentation of the brundtland report on various dimensions of sustainable development in 1987. in the beginning, the environmental dimension of sustainable development was more important compared to other fig. 2. a systemic model of residential satisfaction source: (amerigo & aragones, 1997) theoretical model of mccrea (mccrea, 2007) mccrea sought to find the relations between the objective dimensions of the urban environment and the mental evaluations based on them, as well as the effects of psychological processes and residential mobility on these relations. his findings indicate a weak correlation between the objective dimensions of the environment and the subjective assessments based on it. this indirect relation arises from the effect of people's comparative standards on their mental perception of the objective aspects of the environment. journal of sustainable architecture and civil engineering 2021/2/29 54 (2011) recognized accessibility (job, open space, neighborhood services), social capital, health, social cohesion, local participation, and a sense of place as indicators of social sustainability. the theoretical foundations of social sustainability show that any actions that might change basic social relations are not acceptable in the process of development. the purposes of any kind of development should more focus on improving the quality of humans’ life and meeting their needs. therefore, the general strategy regarding the issue of social sustainability is social development based on responding to welfare, cultural and psychological needs, the need for adaptability, and the need for growth and prosperity (nazarpour, 2000). the components of social sustainability can be summarized into four groups: social justice, security, participation, and standard (quality) of living. the indicators of these components, which are related to the design of the environment, are shown in table 2. a part of the questionnaire which was distributed among participants (residents of the baghe behesht complex) was based on measuring the perceived quality of these indicators in the living space, and the other part measures their willingness to apply these indicators. table 2 components and indicators of social sustainability in relation to architectural design components and indicators no social justice access to the facilities 1 the similarity of units in having good light and view 2 proper access to municipal services 3 security physical security in the interior spaces 4 feeling of psychological security in the interior spaces 5 physical security in the open spaces of the residential complex 6 feeling of psychological security in the open spaces of the residential complex 7 participation a sense of belonging to the complex 8 opportunity to establish social interactions with neighbors 9 standard of living quality of environmental comfort inside residential units 10 quality of environmental comfort in open and semi-open spaces of the complex 11 quality of housing response to residential needs 12 derived from: (qanbari & farhadi, 2017; murphy, 2012; weingaertner & moberg, 2011; thin, lockhart, & yaron, 2002) the effects of the components of social sustainability on residential satisfaction regarding the relationship between social sustainability and residential satisfaction, karuppannan & sivam (2011) examined the impact of urban form on social sustainability and residents' satisfaction at the neighborhood level. the results of this study demonstrated that the provision of high quality and well-located open space at the precinct level, mixed land use and good accessibility to the public realm and social infrastructure play an important role in increasing social sustainability and residents’ satisfaction. howley et al. (2009) believe that it is not only high density per se that is the source of dissatisfaction for residents but rather other related factors such as environmental quality, noise, lack of community involvement, traffic and lack of services and facilities. ríos & moreno-jiménez (2012) focused on the concepts of place identity, social identity, residential satisfaction and community participation among immigrant and native populations. they found that greater place identity was seen to be linked with greater community participation and residential satisfaction. ibrahim (2020) assessed the level of satisfaction with public housing offered by the uae government to its citizens. the survey results show that the majority of residents are mostly satisfied, although the overall level of satisfaction with the functionality of the building and public facilities provided was generally higher than that related to the social environment in the residential district. 55 journal of sustainable architecture and civil engineering 2021/2/29 according to the results obtained from the study of basic theories on the concept of residential satisfaction, the scale of the investigation of this concept is important in determining the variables and indicators involved. in the case of measuring residential satisfaction on the scale of residential complexes, three main variables play role in determining residential satisfaction as follows: the quality of housing architecture, which includes formal, functional, and semantic dimensions. quality of social sustainability components and finally, residential desires associated with social sustainability. another point about the qualities of variables is the necessity to measure the perceived qualities, which is possible to measure their impacts on residential satisfaction. the variables of residential desires associated with social sustainability and perceived quality of social sustainability were measured in the four titles of social justice, participation, security, and standard of living by the 12 indicators mentioned in table 1. the measurement of the perceived quality of housing architecture has also been done in three material, psychological and semantic dimensions as described in table 3. qualitative aspects of housing architecture no semantic quality using symbols and signs formed based on culture and beliefs 1 transfer of concepts through using semantic components such as light, water, etc. 2 application of various geometries in the plan to transmit meanings of shapes 3 using various colors and textures to transmit their related meanings 4 functional quality providing physical security and environmental comfort 5 compatibility of dimensions of spaces with considered functions 6 quality of functional relationships between spaces 7 formal quality preserving static and visual balance in architectural forms 8 the aesthetic quality of the design 9 compatibility of architectural forms with the surrounding urban fabric 10 table 3 indicators of different aspects of the quality of housing architecture determinant indicators of residential satisfaction are defined based on meeting the residential needs of the target community according to table 4. the validity of the questionnaire was confirmed by interviewing a group of experts, and the indicators for measuring the variables were developed on this basis. derived from: (bemanian & zandi, 2018; altman, 1975; naghizadeh, 2012; raeisi, 2019; pirnia, 1997) table 4 indicators of residential satisfaction based on meeting residential needs residential satisfaction indicators based on meeting residential needs no residential needs of the material dimension responding to physical functions 1 providing physical security 2 providing necessary daylight for spaces 3 providing climatic comfort 4 residential needs of the psychological dimension preservation of individual and family boundaries 5 providing a context for understanding sensory beauty 6 inducing a sense of peace and psychological security 7 providing a context to promote social interactions 8 residential needs spiritual dimension providing a context for individual and family privacy 9 providing a context for understanding the concepts of natural phenomena 10 providing a context to understand the spiritual beauty and flourishing of cultural values 11 derived from: (raeisi, 2019; bemanian & zandi, 2018; altman, 1975; azizibabani & bemanian, 2019) journal of sustainable architecture and civil engineering 2021/2/29 56 the theoretical framework of the research is explained based on the relationship of variables so that the residential desires of residents regarding the application of the components of social sustainability in architecture form the basis of initial expectations and are considered as an independent variable in this study. although personal and cultural factors affect these residential desires but examining how they are affected is not within the scope of this study. perceived quality of applying indicators of social sustainability has been considered as a dependent of mentioned residential desires. in this regard, it is hypothesized that the perceived quality of a component will decrease due to the increase residential satisfaction indicators based on meeting residential needs no residential needs of the material dimension responding to physical functions 1 providing physical security 2 providing necessary daylight for spaces 3 providing climatic comfort 4 residential needs of the psychological dimension preservation of individual and family boundaries 5 providing a context for understanding sensory beauty 6 inducing a sense of peace and psychological security 7 providing a context to promote social interactions 8 residential needs spiritual dimension providing a context for individual and family privacy 9 providing a context for understanding the concepts of natural phenomena 10 providing a context to understand the spiritual beauty and flourishing of cultural values 11 the theoretical framework of the research is explained based on the relationship of variables so that the residential desires of residents regarding the application of the components of social sustainability in architecture form the basis of initial expectations and are considered as an independent variable in this study. although personal and cultural factors affect these residential desires but examining how they are affected is not within the scope of this study. perceived quality of applying indicators of social sustainability has been considered as a dependent of mentioned residential desires. in this regard, it is hypothesized that the perceived quality of a component will decrease due to the increase in its related residential desire, and the reason for such a hypothesis is the increase in the level of initial expectations about that component. in addition, the variable of perceived quality of housing architecture is affected by the perceived quality of social sustainability components and all three variables will affect residential satisfaction. the conceptual figure 3: conceptual model of the effects of the components of social sustainability on residential satisfaction. source: authors in its related residential desire, and the reason for such a hypothesis is the increase in the level of initial expectations about that component. in addition, the variable of perceived quality of housing architecture is affected by the perceived quality of social sustainability components and all three variables will affect residential satisfaction. the conceptual model of these relations is depicted in fig. 3. to verify the conceptual model and answer the research questions, the mentioned relations between the variables should be tested in a real context. in this regard, baghe behesht residential complex located in saadatabad neighborhood of tehran has been selected due to having a desirable level of indicators related to the variables of the conceptual model. the level of occupancy in the complex is such that the dominance of open spaces over masses is evident, and the landscape design of this complex has fig. 3 conceptual model of the effects of the components of social sustainability on residential satisfaction source: authors field study fig. 4 (1) hierarchy in the open spaces of the complex. (2) overview of the complex from the south side. (3) semipublic spaces for social interactions. (4) forest parks on the south side of the complex source: authors field study to verify the conceptual model and answer the research questions, the mentioned relations between the variables should be tested in a real context. in this regard, baghe behesht residential complex located in saadatabad neighborhood of tehran has been selected due to having a desirable level of indicators related to the variables of the conceptual model. the level of occupancy in the complex is such that the dominance of open spaces over masses is evident, and the landscape design of this complex has led to improving the quality of social interaction spaces between residents. the forest park on the south side of the complex, which is exclusively available to residents, is considered as a context for social interactions between them. the hierarchy of public, semi-public, and semi-private spaces in the level of the complex is customary observed, and the proper separation of pedestrian paths from vehicle paths has made it possible to form the context of interactions of different social groups from residents of a block to residents of a neighborhood unit and residents of the whole complex. the physical control of the interior spaces of the complex and the inclusion of active and passive surveillance in the open spaces has led to an increase in the quality of indicators of physical security. also, the design of the site and locating of the masses have been done based on the climatic characteristics of tehran, which leads to the provision of comfortable conditions to an acceptable level at the participatory spaces. figure 4: (1) hierarchy in the open spaces of the complex. (2) overview of the complex from the south side. (3) semi-public spaces for social interactions. (4) forest parks on the south side of the complex. source: authors a questionnaire with the participation of 251 residents was used to measure the variables related to the conceptual model and explain the relationship between them. data were collected and analyzed between january to april 2021. the questionnaire which was designed based on a 5point likert scale, consists of 45 questions in four sections that directly measure the indicators presented in tables 2, 3, and 4. regarding the 12 indicators of table 2, in addition to the perceived field study to verify the conceptual model and answer the research questions, the mentioned relations between the variables should be tested in a real context. in this regard, baghe behesht residential complex located in saadatabad neighborhood of tehran has been selected due to having a desirable level of indicators related to the variables of the conceptual model. the level of occupancy in the complex is such that the dominance of open spaces over masses is evident, and the landscape design of this complex has led to improving the quality of social interaction spaces between residents. the forest park on the south side of the complex, which is exclusively available to residents, is considered as a context for social interactions between them. the hierarchy of public, semi-public, and semi-private spaces in the level of the complex is customary observed, and the proper separation of pedestrian paths from vehicle paths has made it possible to form the context of interactions of different social groups from residents of a block to residents of a neighborhood unit and residents of the whole complex. the physical control of the interior spaces of the complex and the inclusion of active and passive surveillance in the open spaces has led to an increase in the quality of indicators of physical security. also, the design of the site and locating of the masses have been done based on the climatic characteristics of tehran, which leads to the provision of comfortable conditions to an acceptable level at the participatory spaces. figure 4: (1) hierarchy in the open spaces of the complex. (2) overview of the complex from the south side. (3) semi-public spaces for social interactions. (4) forest parks on the south side of the complex. source: authors a questionnaire with the participation of 251 residents was used to measure the variables related to the conceptual model and explain the relationship between them. data were collected and analyzed between january to april 2021. the questionnaire which was designed based on a 5point likert scale, consists of 45 questions in four sections that directly measure the indicators presented in tables 2, 3, and 4. regarding the 12 indicators of table 2, in addition to the perceived field study to verify the conceptual model and answer the research questions, the mentioned relations between the variables should be tested in a real context. in this regard, baghe behesht residential complex located in saadatabad neighborhood of tehran has been selected due to having a desirable level of indicators related to the variables of the conceptual model. the level of occupancy in the complex is such that the dominance of open spaces over masses is evident, and the landscape design of this complex has led to improving the quality of social interaction spaces between residents. the forest park on the south side of the complex, which is exclusively available to residents, is considered as a context for social interactions between them. the hierarchy of public, semi-public, and semi-private spaces in the level of the complex is customary observed, and the proper separation of pedestrian paths from vehicle paths has made it possible to form the context of interactions of different social groups from residents of a block to residents of a neighborhood unit and residents of the whole complex. the physical control of the interior spaces of the complex and the inclusion of active and passive surveillance in the open spaces has led to an increase in the quality of indicators of physical security. also, the design of the site and locating of the masses have been done based on the climatic characteristics of tehran, which leads to the provision of comfortable conditions to an acceptable level at the participatory spaces. figure 4: (1) hierarchy in the open spaces of the complex. (2) overview of the complex from the south side. (3) semi-public spaces for social interactions. (4) forest parks on the south side of the complex. source: authors a questionnaire with the participation of 251 residents was used to measure the variables related to the conceptual model and explain the relationship between them. data were collected and analyzed between january to april 2021. the questionnaire which was designed based on a 5point likert scale, consists of 45 questions in four sections that directly measure the indicators presented in tables 2, 3, and 4. regarding the 12 indicators of table 2, in addition to the perceived field study to verify the conceptual model and answer the research questions, the mentioned relations between the variables should be tested in a real context. in this regard, baghe behesht residential complex located in saadatabad neighborhood of tehran has been selected due to having a desirable level of indicators related to the variables of the conceptual model. the level of occupancy in the complex is such that the dominance of open spaces over masses is evident, and the landscape design of this complex has led to improving the quality of social interaction spaces between residents. the forest park on the south side of the complex, which is exclusively available to residents, is considered as a context for social interactions between them. the hierarchy of public, semi-public, and semi-private spaces in the level of the complex is customary observed, and the proper separation of pedestrian paths from vehicle paths has made it possible to form the context of interactions of different social groups from residents of a block to residents of a neighborhood unit and residents of the whole complex. the physical control of the interior spaces of the complex and the inclusion of active and passive surveillance in the open spaces has led to an increase in the quality of indicators of physical security. also, the design of the site and locating of the masses have been done based on the climatic characteristics of tehran, which leads to the provision of comfortable conditions to an acceptable level at the participatory spaces. figure 4: (1) hierarchy in the open spaces of the complex. (2) overview of the complex from the south side. (3) semi-public spaces for social interactions. (4) forest parks on the south side of the complex. source: authors a questionnaire with the participation of 251 residents was used to measure the variables related to the conceptual model and explain the relationship between them. data were collected and analyzed between january to april 2021. the questionnaire which was designed based on a 5point likert scale, consists of 45 questions in four sections that directly measure the indicators presented in tables 2, 3, and 4. regarding the 12 indicators of table 2, in addition to the perceived led to improving the quality of social interaction spaces between residents. the forest park on the south side of the complex, which is exclusively available to residents, is considered as a context for social interactions between them. the hierarchy of public, semi-public, and semi-private spaces in the level of the complex is customary observed, and the proper separation of pedestrian paths from vehicle paths has made it possible to form the context of interactions of different social groups from residents of a block to residents of a 57 journal of sustainable architecture and civil engineering 2021/2/29 neighborhood unit and residents of the whole complex. the physical control of the interior spaces of the complex and the inclusion of active and passive surveillance in the open spaces has led to an increase in the quality of indicators of physical security. also, the design of the site and locating of the masses have been done based on the climatic characteristics of tehran, which leads to the provision of comfortable conditions to an acceptable level at the participatory spaces. a questionnaire with the participation of 251 residents was used to measure the variables related to the conceptual model and explain the relationship between them. data were collected and analyzed between january to april 2021. the questionnaire which was designed based on a 5-point likert scale, consists of 45 questions in four sections that directly measure the indicators presented in tables 2, 3, and 4. regarding the 12 indicators of table 2, in addition to the perceived quality, residential desires have also been measured. in addition to these 45 questions, demographic data including age, gender, marital status, ownership status, and length of residence in the complex were also collected. however, the study of the effects of demographic variables on conceptual model variables has not been fig. 5 average percentage of indicators related to research variables quality, residential desires have also been measured. in addition to these 45 questions, demographic data including age, gender, marital status, ownership status, and length of residence in the complex were also collected. however, the study of the effects of demographic variables on conceptual model variables has not been in the scope of this research and no strong statistical relationship was found in this regard. the average percentage of each of the indicators related to the research variables is shown in the figure 5. figure 5: average percentage of indicators related to research variables. source: authors results regarding the first research question, the results of regression analysis of the relationship between different components of the perceived quality of social sustainability with the residential satisfaction show that the role of the component of the standard of living in predicting changes of residential satisfaction variable was more than other components. in this model, r square = 0.468. table 5: regression model of the relationship between perceived quality of the components of social sustainability and residential satisfaction. source: authors coefficientsa model unstandardized coefficients standardized coefficients t sig. b std. error beta 1 (constant) .136 .031 4.336 .000 perceived quality of the justice component .147 .033 .277 4.374 .000 perceived quality of the security component .201 .042 .306 4.766 .000 perceived quality of the participation component .081 .040 .133 2.029 .044 perceived quality of the standard of living component .360 .057 .405 6.375 .000 a. dependent variable: residential satisfaction regarding the second question of the research, according to the results of the conceptual model test based on quantitative data, residential desires related to social sustainability components have had a reverse effect on the perceived quality of these components and residential satisfaction. there is also a direct relationship between the perceived quality of social sustainability components and the perceived quality of housing architecture and residential satisfaction. amosquality, residential desires have also been measured. in addition to these 45 questions, demographic data including age, gender, marital status, ownership status, and length of residence in the complex were also collected. however, the study of the effects of demographic variables on conceptual model variables has not been in the scope of this research and no strong statistical relationship was found in this regard. the average percentage of each of the indicators related to the research variables is shown in the figure 5. figure 5: average percentage of indicators related to research variables. source: authors results regarding the first research question, the results of regression analysis of the relationship between different components of the perceived quality of social sustainability with the residential satisfaction show that the role of the component of the standard of living in predicting changes of residential satisfaction variable was more than other components. in this model, r square = 0.468. table 5: regression model of the relationship between perceived quality of the components of social sustainability and residential satisfaction. source: authors coefficientsa model unstandardized coefficients standardized coefficients t sig. b std. error beta 1 (constant) .136 .031 4.336 .000 perceived quality of the justice component .147 .033 .277 4.374 .000 perceived quality of the security component .201 .042 .306 4.766 .000 perceived quality of the participation component .081 .040 .133 2.029 .044 perceived quality of the standard of living component .360 .057 .405 6.375 .000 a. dependent variable: residential satisfaction regarding the second question of the research, according to the results of the conceptual model test based on quantitative data, residential desires related to social sustainability components have had a reverse effect on the perceived quality of these components and residential satisfaction. there is also a direct relationship between the perceived quality of social sustainability components and the perceived quality of housing architecture and residential satisfaction. amossource: authors in the scope of this research and no strong statistical relationship was found in this regard. the average percentage of each of the indicators related to the research variables is shown in the fig. 5. regarding the first research question, the results of regression analysis of the relationship between different components of the perceived quality of social sustainability with the residential satisfaction show that the role of the component of the standard of living in predicting changes of residential satisfaction variable was more than other components. in this model, r square = 0.468. regarding the second question of the research, according to the results of the conceptual model test based on quantitative data, residential desires related to social sustainability components have had a reverse effect on the perceived quality of these components and residential satisfaction. there is also a direct relationship between the perceived quality of social sustainability components and results journal of sustainable architecture and civil engineering 2021/2/29 58 table 5 regression model of the relationship between perceived quality of the components of social sustainability and residential satisfaction source: authors coefficientsa model unstandardized coefficients standardized coefficients t sig. b std. error beta 1 (constant) .136 .031 4.336 .000 perceived quality of the justice component .147 .033 .277 4.374 .000 perceived quality of the security component .201 .042 .306 4.766 .000 perceived quality of the participation component .081 .040 .133 2.029 .044 perceived quality of the standard of living component .360 .057 .405 6.375 .000 a. dependent variable: residential satisfaction the perceived quality of housing architecture and residential satisfaction. amos-version 24 was used to determine the degree of these relations, which the results are shown in fig. 6. fig. 6 the results of conceptual model path analysis version 24 was used to determine the degree of these relations, which the results are shown in figure 6. figure 6: the results of conceptual model path analysis. source: authors discussion and conclusion according to the results of the analysis of the data obtained from the field study, the variable of residential satisfaction in the scale of the architectural quality of residential complexes is a function of the variables of perceived quality of housing architecture, perceived quality of application of the components of social sustainability and residential desires associated with these components. beta coefficients in the model show that the variables of residential desires associated with the components of sustainability and perceived quality of housing architecture had a direct impact on residential satisfaction, but the perceived quality of sustainability components didn't have a significant impact on residential satisfaction and this variable has a significant effect on the residential satisfaction through the variable of housing architecture quality. as residential desires associated with the components of social sustainability increase, the perceived quality of these components and residential satisfaction will decrease equally due to the level of expectations increases. it can be interpreted that in proportion to the increase in the human desire for a particular aspect of the quality of a product, its shortcomings attract more human attention and lead to dissatisfaction with the performance of the product. therefore, the quality deficiency in these components should be noted in interpreting the inverse relationship between the variables involved in the research model. in other words, in situations where the quality of the sustainability components is somewhat high, there will be no relationship between perceived quality, desires, and residential satisfaction, or this relationship will not necessarily be reversed. in addition, it is concluded that the perceived quality of the component of living standards, which is generally related to the housing response to human residential needs, has the greatest impact on improving the quality of housing and the level of residential satisfaction. subsequently, residential satisfaction resulting from the application of the components of social sustainability in architecture source: authors according to the results of the analysis of the data obtained from the field study, the variable of residential satisfaction in the scale of the architectural quality of residential complexes is a function of the variables of perceived quality of housing architecture, perceived quality of application of the components of social sustainability and residential desires associated with these components. beta coefficients in the model show that the variables of residential desires associated with the components of sustainability and perceived quality of housing architecture had a direct impact on residential satisfaction, but the perceived quality of sustainability components didn't have a significant impact on residential satisfaction and this variable has a significant effect on the residential satisfaction through the variable of housing architecture quality. as residential desires associated with the components of social sustainability increase, the perceived quality of these components and residential satisfaction will decrease equally due to the level of expectations increases. it can discussion and conclusion 59 journal of sustainable architecture and civil engineering 2021/2/29 be interpreted that in proportion to the increase in the human desire for a particular aspect of the quality of a product, its shortcomings attract more human attention and lead to dissatisfaction with the performance of the product. therefore, the quality deficiency in these components should be noted in interpreting the inverse relationship between the variables involved in the research model. in other words, in situations where the quality of the sustainability components is somewhat high, there will be no relationship between perceived quality, desires, and residential satisfaction, or this relationship will not necessarily be reversed. in addition, it is concluded that the perceived quality of the component of living standards, which is generally related to the housing response to human residential needs, has the greatest impact on improving the quality of housing and the level of residential satisfaction. subsequently, residential satisfaction resulting from the application of the components of social sustainability in architecture has been due to the improvement of living standards by improving the quality of housing architecture. this result is consistent with glaster's theory about the importance of housing architecture quality in improving residential satisfaction. future researches based on the conceptual model of this research help refine it and in this regard, it is suggested that different case studies be investigated with different qualities of the components of social sustainability. it is also recommended that future studies focus on the impact of personal and cultural factors on research 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(2011). relevance between acquiescence of habitations and impacts on relationships (case study: ekbatan and behjatabad tehran). hoviatshahr, 5(8), 103-118. mohammadhossein azizibabani ph.d. student in architecture, department of architecture, faculty of art, tarbiat modares university, tehran, iran main research area affordable housing design, sustainable design address faculty of art, tarbiat modares university, tehran, iran. tel. +989120929844 e-mail: m.azizibabani@modares.ac.ir mohammadreza bemanian professor department of architecture, faculty of art, tarbiat modares university, tehran, iran main research area iranian islamic architecture, architectural planning and management address faculty of art, tarbiat modares university, tehran, iran. tel. +98(21)82883711 e-mail: bemanian@modares.ac.ir mansour yeganeh assistant professor department of architecture, faculty of art, tarbiat modares university, tehran, iran main research area architecture and converging technologies, behavioral and cognitional territories in architecture, new methods in architectural design, modeling and fabrication. architecture and renewable and new energies address tel. +98(21)8288371108 e-mail: yeganeh@modares.ac.ir about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 33 the role of the river in the city centre and its identity justina mačiukėnaitė*, ingrida povilaitienė kaunas university of technology, institute of architecture and construction, tunelio st. 60, lt-44405 kaunas, lithuania *corresponding author: justina.maciukenaite@gmail.com http://dx.doi.org/10.5755/j01.sace.4.5.4820 since the first human beings started to live sedentary lifestyle, the rivers have had significant role in the life of people and in the development of the settlement. the main functions of the river were: protection, crafts related with water and maintenance of industrial enterprises. therefore, the shape of the city that time highly depended on the river. however, nowadays the connection between the society and river is unclear. according to the historical and scientific literature, the changes of the river role for the city centre and its identity will be analysed. current situation in lithuania through the prism of implemented practical projects will be revealed. review of successful practical experience abroad will be made and the examples of the river embankment design in the centre cities in denmark, slovenia, austria and france will be presented in this paper. keywords: river influence, embankment, riversides, urban identity, urban development. 1. introduction nowadays the eco-movement, eco-lifestyle, eco-food, eco-materials and other eco-ideas are spreading across the world. nature by itself and what comes from it have become more significant than human made things. this trend is observed in the field of architecture and urbanism as well. people prefer spending their leisure time in the nature or at least they are trying to find public recreational spaces in the urban areas. rivers, lakes and other water reservoirs with their waterfronts could play quite significant role here. due to this, the flurry of the city and river reconnection is among architects, urban planners, government representatives and businessmen for a while. however this point of view (friendly point of view to the nature) was not the same in all times. the relationship between the man and water, the functional usage of the river and the influence, what river had made for the people life, has been changing for several times throughout the history. the aim of this paper is to review the changes of the river role in the centres of lithuanian cities and reveal the today’s peculiarities of riversides management. besides the river had not only different significance depending on the time but also the different points of view were dominating and the different issues were relevant even in the same period. especially it is distinctly visible nowadays. there are scientists and theorists who pay their attention to the river however they are looking through the prism of their interests and sometimes they are looking from the different sides. due to this the short review of the different aspects of riverside management in the scientific literature (1) will be done in this paper. furthermore, the analysis of the historical changes of river role (2) in the city and especially in the city centre will be done. the reasons of historical changes (why), circumstances (when) and consequences (how) will be analysed. definitely, not all of the changes affected city in the positive way. therefore the main relevant problems of the river in the city centre (3) we face-in today will be discussed here as well. the current role of the river in the centres of lithuanian cities and in their identity (4) will be analysed by reviewing the riversides management projects implemented recently. finally the tendencies of riversides management abroad (5) will be discussed (what are the priorities, how the river participates in the life of the city as part of one sustainable structure). 2. methods the analytical, comparative, descriptive methods were applied to prepare this paper. in order to get the complete view of current situation of the river role for the city centre, the detail analyse of historical sources, architectural and urban planning theoretical researches has been done. majority of the monographs, studies or articles touch the relevant topic just in a fragmentary way or just from one point of view. therefore this paper is an attempt to analyse the most important individual observations. comparative method was applied: to compare the opinion differences between the theorists; to reveal the changes of the river role throughout the history and find out darnioji architektūra ir statyba 2013. no. 4(5) journal of sustainable architecture and civil engineering issn 2029–9990 . 34 how the river impacted the identity of settlement; to check how the theoretical knowledge was adapted in the different practical projects in lithuania and abroad. descriptive method was applied to reveal peculiarities of practical development of the riversides. the examples of successfully implemented management projects of riversides in lithuania and abroad were described in this paper. it can be stated that nowadays the tendency of adapting riverside area for public needs is observed. therefore in foreign examples riverside has clear and appropriate functions and the riverside as the public space fully represents the main open space in the city centre. unfortunately, the lithuanian case is not so successful. despite that according valid juridical base the riverside should be left unbuilt, this requirement is more orientated to the ecological protection of the river, not for the public interest. 3. a variety of opinions on the river role river and its influence for the city centre is quite broad topic. therefore it is discussed in different aspects in the lithuanian and foreigner scientists’ works of urban planning theory and history. although there is a possibility to classify (though quite roughly) all these different points of view accordingly to the main object of the interests: ▪ function (river as a ”functional cog”) ▪ society (river as public, open space) ▪ ecology (river as ecological stabilizer) ▪ visibility (river as formant of visual identity) under the cover of the first group “functional cog” there are the scientists and urban planners who analyse river as a part of urban structure, however they bring out just the functional importance and tangible benefits. le corbusier, one of the pioneers of what is now called modern architecture, especially highlighted the functional importance of the river. in his opinion, river is the infrastructural object, something like liquid railway (rekevičius 2010). although, it is very technical point of view, more humane thoughts about river could be found in the researches of other authors. according ch. alexander, the need that people have for water is vital and profound. he wrote “…people will build places near the water because it is entirely natural; but that land immediately along the water’s edge must be preserved for common use. to this end the roads which can destroy the water edge must be kept back from it and only allowed near it when they lie at right angles to it.”(alexander et al. 1977). this quote expresses importance of riverside as public, open place and space. possibilities of embankment development as open space for city dwellers were analysed in the aesthetic, compositional approach by c. moughtin (1999). the formation of the embankment is described by k. lynch (1990) as well. furthermore, there are even standards and design strategies created for the riversides planning (buttler et al., 2006). following overall strategies for the design of a successful waterfront area continuity, variety, sequence, and connection should be considered. danish architect and urban design consultant j. gehl (2010) has focused on improving the quality of urban life by creating humanistic open spaces (including riversides) and re-orienting city design towards the pedestrian and cyclist. this perception of the riverside as public space is mostly common among lithuanian urban designers and architects as well. development of the river embankment in the context of the other open spaces is discussed in the works of a. miškinis (1991), k. šešelgis (1996), j. vanagas (2008). k. jakovlevas-mateckis analyses river from the ecological perspective. he claims that rivers and riversides are a part of natural frame and its carry out essential ecological compensation function. riverside slopes and its greenery and even brushwood are like the lungs of the city and it encourages formation of horizontal and vertical air flow. this process ensures clean air flow and polluted air displacement into the upper layers of the atmosphere. the riverside buffer, where, according to the laws of lithuania, urbanization is not allowed, should be left unbuilt and the width of it should not be narrowed. during the process of shaping the urban environment, closer attention should be paid for the river identity enhancement, visual quality significance, improvement of the access to the water and increase of recreation opportunities for the urban community (jakovlevas-mateckis 2006). river, as one of the most relevant factors for the visual identity, is touched in many of the studies that deal with peculiarities of settlements. valleys of nemunas and neris, their influence for the kaunas identity have been analysed by j. bučas (1994), m. purvinienė (1980), j. kamičaitytėvirbašienė (2005). the thorough examination about the river influence on vilnius visual identity has been made in the monograph “protection and development principles of vilnius visual identity” by z. j. daunora, s. kirvaitienė, a. vyšniūnas (2004). the proposals for the development of neris riversides are discussed in the articles of p. zaviša (2012), j. glemža (2011), m. kajackaitė (2011). certainly, there are more aspects of the river role for the city centre, which might be not so substantial. however these “subtopics” still are quite meaningful and should be mentioned as they closely interact, overlap and influence the main objects of interest, which were defined before. the changes of river influence for the urban structures throughout the history have been analysed by t. grunskis and l. nekrošius (2004). g. milerytė (2008) has made the case study and collected the information about the role of the rivers in kaunas city life in interwar period. after industrial revolution not a few enterprises have been left along the river. nowadays, when the eco-movement is going on, the conversion of industrial areas (especially the ones, which remained in the central parts of the cities or along the rivers and today are abandoned) is very topical issue. therefore k. matulevičius and j. šliogerienė (2011), e. garrick and i. alistratovaitė (2005), l. nekrošius (2006) focused their interest on the conversion of industrial areas in the river embankments (experience in lithuania and in foreign countries). besides, from time to time the individual opinions about the river are revealed in the publicist articles, personal interviews or public events. summarizing, it can be stated that such broad discussion not only in the scientific studies of lithuanian and foreign scientists, but also in the other media streams, shows that the topic of the river role in the city centre and in the life of people is very relevant. 35 4. retrospective point of view (lithuanian case) inevitably, the urban development is influenced by political, sociocultural events (both in global and in local scales). the most significant events in lithuania, that have had an impact on the evolution of the settlements and that have changed the relation between rivers and human were: establishment of lithuania state (baltic tribes unification) in the 13th century; victorious battle of grunwald in the 15th century; wallach reform in the 16th century; the third partition of the polish–lithuanian commonwealth in 1795; the declaration of independence during the interwar period; the annexation of lithuania by the soviet union (1940–1990) and the restoration of lithuania’s independence in 1990. the changes in town and the river’s functions depending on the historic evolution of lithuanian settlements are showed in table 1. there is an opinion that river trade in lithuania started in 5th–7th century. the goods could have been transported by the trade route of nemunas (žulkus 2002). the trade was very important in the mediaeval times, although till the 13th century the conditions for the trade were not very favourable because of political and military emergencies. craft and trade of lithuanian cities were hindered by existing well developed cities of rus and constant struggle with the teutonic order. klaipėda was the first settlement which was granted cities rights (in 1254). however, it belonged to the livonian order. the provision of the selfgovernment and trade rights for the cities (in the grand duchy of lithuania) started only by the end of 14th century. situation has changed and more favourable conditions for the commercial development (including river trade) were formed when the teutonic forces were finally defeated in the battle of grunwald in 1410. the stage of maturation and prosperity of lithuanian settlements started. (šešelgis 1996). however, from the middle of 17th century till the end of 18th century political and economic cataclysms (struggles for power and domination between the nobility, plague and famine) led the country to the decadence (grunskis et al. 2004). the network of settlements was thinned out. the population decreased so much that many towns turned into rural villages or become extinct. global industrialisation process, which has had a huge impact to the urban and economic development of the world cities, affected lithuania as well. subsequent changes of table 1. the historic evolution of lithuanian settlements and the relationship changes between town and the river’s functions period conditions main function of the settlements/ other functions location of the settlements main function of the river/ other functions 13th–15th century unfavorable: wars with crusaders; competition with other rus towns defense/ trade, administration strategically important locations: nearby castles and fortresses; along the rivers or lakes. defensive barrier/ logistics, fishery, crafts, trade, maintenance 15th–16th century more favorable: in 1410 the crusaders were defeated in the battle of grunwald trade/ administration (autonomy), defense by important land roads trade, fishery, logistics, crafts/ maintenance 16th–17th century favorable: economic and cultural prosperity trade/ administration, agriculture (in the small settlements) intensive colonization of užnemunė: settlements in the new places; growing of the former settlements trade, fishery, logistics, crafts/ maintenance 17th centuryend of the 18th century unfavorable: famine, plague; disagreements among nobility defense/ trade, administration remained at the former locations: only few new settlements were established in the areas where the density of populations was not high. defensive barrier/ logistics, fishery, crafts, trade, maintenance 1795–1918 more favorable: technical achievements in19th century; growth of capitalist relations trade/ administration nearby newly built routes: railway lines; highways trade, fishery, logistics, industry/ maintenance 1918–1940 more favorable: reform of agriculture; the abolition of serfdom trade/ administration remained at the former locations: reconstruction of the settlements destroyed during the first world war trade, fishery, logistics, industry/ maintenance 1940–1990 depending on the type of settlement: central; assisting; not being developed administration/ trade (?) the unified system of settlements: developing of the former settlements; design and building of the new settlements maintenance, industry/ trade, fishery, logistics 1990–now depending on the political strategy: decreasing population; economic crisis; lack of the investment administration/ (?) remained at the former locations: urban sprawl around the biggest cities recreation (?) fishery (?)/ logistics (?) industry (?) maintenance (?) 36 the lithuanian settlements structure also were influenced by a wider modernisation process, where social change and economic development were closely related with technological innovations. the majority of lithuanian lands, after the third partition of the polish–lithuanian commonwealth in 1795, were under control of imperial russia. the way of urban development changed substantially. cities were planned in consistent and regular basis, thought like a part of russian empire urban system. in the discussed context, riverside evolution as the city’s public space was closely related with trading ports and markets. public space along the river was evolving as far as trade, crafts and other activities related with water were developed in the city. from the early 20th century, dams and hydroelectric power plants were started to build. the riversides have become a strategically important place for the setting up the industry, since river facilitated the transportation of raw materials and other goods. despite the fact that during the interwar period the significance of the rivers as transportation axes was reduced because of rising of other transport routes (land roads, railways) development, there were new functions for the river found. it started to be used for the recreational purpose and river travel has attracted much interest. colossal alterations happened while lithuania was in the soviet union. changes touched landscape of both rural and urban areas. the reclamation decreased ecological stability. the negative consequences of it were: uncontrolled rivers mode, drought, overgrowth, decline of the species diversity, deflation increases and etc. most of the stream and some rivers turned into canals (kraštovaizdžio formavimosi… 2008). still during the soviet years, rivers were used quite intense. self-propelled and towed barges floated by the rivers and the regular tours of high-speed passenger ships were organised. river water also was used for maintenance of metal processing, chemical and paper plants. 5. challenges of the river role in the city centre today according to the historical retrospective and present situation of the river role in the city centres there could be some relevant problems distinguished we face today. ▪ functional issues. the role of the river by itself is significantly decreasing. functional potential of the river is not used sufficiently including inland waterway transport (passenger and goods transportation), water tourism and fishery (recreational and commercial fishing). after the restoration of lithuanian independence, the functional role of the river in lithuanian cities has not increased, but only eroded further. according to the data of lithuanian department of statistics about the passenger and goods transportation via water routes from 1995 till 2012, the functional use of the rivers has been growing while general passenger transportation has been decreasing. however, this growth was not as fast as it could be expected. definitely, the scale of transportation is highly influenced by the general economy. the highest level was reached in 2008, when there was economic boom and after that it started to fall down. the impact of global economic crisis was not so significant in the sector of goods transportation (it recovered in a year) as it was in the sector of passengers’ transportation (the marginal growth was observed just from 2012). in any case, it can be predicted that the significance of the waterway transport will increase in the future depending on the growth of global economy and will take more significant part in the field of transportation due to the possibility to transport high dimensional loads and due to the lower costs. ▪ social benefits and loss. in lithuanian case, not only the river is losing it’s function, riversides is on this way as well. global trends reveal riverside as pubic, open spaces. however in lithuania, (except few successful examples) riverside is still considered as a way (route) to reach the place where to spend leisure time and not as the final destination (transit versus stay in). there are cases where the main function along the river is transit or the degradation of the previous function led to the situation where no function is at all and the area is abandoned and unused while it could be nice public space. for example, the river embankments are occupied by industrial buildings and the riversides are enclosed from society. such buildings are along the rivers embankments in klaipeda, kaunas cities centres and etc. moreover, green riversides are without functional script – the potential is not used like island of nemunas river in kaunas city centre or green place close to neris river in vilnius centre. on the other hand, nowadays there are some good initiatives to change the situation which will be discussed in the next chapter. ▪ ecological problems. the situation of river water quality is not the biggest ecological issue in lithuania (most of the rivers meet the criteria of good and moderate water quality classes (aplinkos ministerija 2011)). however, there are not enough equipped green spaces along the rivers in the cities which could be an integral part of urban green spaces system and which not only could fulfil the social aspect as public space but also would guarantee the ecological balance of the city. after the industrial revolution growth of industry is threatening the world with the ecological problems. the car cult was huge in 20th century in europe but still is vital in lithuania: the roads were built along the riversides, open spaces were converted into parking place and the link between river and society was lost in city centre (gehl 2010). for example kaunas city centre where the karalius mindaugas street (which goes along the nemunas river) was widened and narrow embankment part with steep slope was formed to separate pedestrian flows from the flows of motor vehicles during the 37 soviet period. moreover garage of shopping mall is made above this street close to nemunas river in 2007. ▪ challenges of visual identity. there are a lot of examples around the world where the river is the main formant of the identity of the city. however, in lithuania river always has been the border of the city (protection from the world outside), not the axis. it is sad to admit, but the river (valuable feature) given by nature is not accepted as something exceptional or peculiar. almost all of the biggest lithuanian cities are located near the rivers (vilnius, kaunas, klaipeda, panevezys). rivers and their slopes are defined as the most valuable attributes of urban identity in the strategic planning documents of these cities. however, the first association of almost of all of these cities is related with some single (usually architectural) object, but not with water or river. klaipeda is the exception here as it is port city, city by the sea. tempting idea is, that such river as it is in venice, amsterdam or hamburg (integral and important part of the city’s identity) gradually will come from the strategic plans of the cities to the society’s perception. 6. lithuanian and european examples lithuanian case. the perception about turning to the cities’ rivers slowly proceeds in lithuania. many architectural, urban contests, workshops were designed to revitalize rivers of cities centres and still appear. taking into account vilnius city example, creative architectural workshop for vilnele’s riversides revitalization was presented in 2008. although the revival works of territory moved a little, students and young people prefer to spend their time close to the river. there are art and cultural centres formatting (vilniaus architektūros… 2008). neris’ embankments revitalization ideas were presented during workshop “design forum” in 2009. guggenheim museum contest was organized to reveal the idea how is possible to revive neris riverside forming its territory as social place. however, neris embankments are still green place without clear zoning or some architectural elements nevertheless is favourite citizens open green place. according to g. čaikauskas, territory „could be saved, maybe still preserved as the green space and authentic place for people to communicate“(čaikauskas 2009). also, well-known revitalization projects (“memelis city” quarter, “sea gates” quarter and etc.) of dane riversides and industry territory close to dane river outfall and kursiai lagoon were prepared in klaipeda city. moreover, the project of commercial function quarter was implemented close to žvejai street. the building-up was formatted close to dane river and cafes with outdoor terraces let enjoy the flowing watercourse (fig. 1). dane riverside is adjusted in front of these buildings as well: the paths were made, benches were set. however, the benches were fixed in close to the dane river, but they were not oriented and turned away from the water. fig. 1. klaipėda riverfront, lithuania (klaipėda.... 2011) despite the fact that, the development of “memelis’ city” quarter is left in project stage, “sea gates” quarter work is in process: riverfront historical buildings were restored and renewed, cafes, hotel rooms were established inside. besides, dane riverside was developed, castle harbour was expended, lightning, benches were installed and pedestrians’ paths were created. moreover, after big, isolated industry territory reconstruction work close to dane riverside and kursiai lagoon appeared a possibility to reopen dane riverside to city’s residents, tourists (jūros vartai… 2013). on the other hand, there are still closed and not adapted dane riversides for using left. there are lithuanian resorts with exceptional recreational potential like druskininkai, birstonas, which are situated in nemunas loops. furthermore, these towns like urban phenomenon do not compete with nature, but organically merge with present natural environment and the role of the river in cities centers is exploited too. for example, according to general plan of druskininkai and survey of present situation, nemunas riverside is being used actively by city’s guests, residents all over the year (druskininkų savivaldybės teritorijos… 2012). nemunas riverside is rich with greenery, planted parks. there are pathways, cycling routs paved. also, relaxation zones are established even pier is made. what is more, riversides are lively not only because of pedestrians, cyclists, but fishermen are spread too (fig. 2). on the other hand, more access and connections with the other nemunas’ riverside is needed. fig. 2. druskininkai riverfront in spring, lithuania (druskininkai... 2009) birstonas is other resort example, situated in nemunas loops regional park territory and riverside distinguishes with possibility to look over nemunas river clearly. here is pier, pathways as well as other infrastructure installed (birštono savivaldybės teritorijos… 2010). in spite of that, 38 mixed use zones are missing. therefore, the view from the other riverside is not such clear and the connection with nemunas river is not perceptible. the focus point is kaunas city settled close to nemunas and neris rivers’ junction. kaunas is another example with big theoretical attempts to revitalize riversides of city‘s centre and attract society. there are many contests done: architecture and urban design competition for the central part development of kaunas city in the valley of the nemunas river (2003), right bank of neris river concept symposium (2007), lituanica – creative workshop (2009), island of nemunas river contest in kaunas (2010), conceptual contest of kaunas castle’s site and neighbouring territories (2011), building and planning contest of brasta’s quarter (brasta street 22, 22a ir 24 in kaunas) (2012) (lietuvos architektų sąjungos… 2013). according to the kaunas city general plan project (2013), there are many bridges marked with a goal to connect opposite riversides and open city centre and river for society. island of nemunas river is marked as public interest area, the opposite riverside close to h. and o. minkovskių street is marked as mixed-built-up, public interest area and extensively used green space. while the riverside of nemunas and neris rivers’ junction (in old town) is set as extensively used green space and opposite embankment is set as intensively built territories (kauno miesto bendrasis… 2013). however, after so many contests and guidelines of general plans (2003, 2013) implementation of the projects moves in small steps. the open spaces close to river or riversides of city centre are realized not completely and management works are in different stage. for instance, the santaka park revitalization work is mostly implemented in old town. considering existing situation, bushes and trees were cut close to river, new paths were paved, and relief was adjusted close to kaunas castle. also, the zones for kids, athletes with outdoor equipment were installed. now bicycle path will be paved to connect cycle rout (kauno miesto… 2013). besides, western part of the park side is left as natural shore where opportunity to walk and enjoy nemunas and neris rivers’ junction is retained. in the southern side of the park beach zone is prepared with sand, just any equipment is not constructed. moreover, stadium is equipped in the east side of santaka park. santaka park with several zoning parts is favourite and visited by kaunas people especially during summer time (fig. 3). fig. 3. santaka park in kaunas, lithuania (santaka... 2013) not so far from santaka park, close to vytautas’ the great church, daugirdas amphitheatre with cafe is adapted to the nemunas riverside. this place is used as a public open space for concerts, art performances and etc. impressive view opens from amphitheatre because it is integrated in front of nemunas’ river. during the summer this riverside is used frequently. moreover, pier is installed in this territory as well. also, island of nemunas river is another important city centre open space in new town close to karalius mindaugas street. despite of many designed conceptual projects this island is still natural and the territory is not developed enough, just sport arena is embedded in island’s east side and green open space is left behind its back. this central natural park could be popular among citizens, but still is not strong functional script adapted to gather people there. furthermore, karalius mindaugas street is a big infrastructure territory which physically and psychologically cut island of the nemunas river from urban system as well as from society. therefore, narrow, long pathway close to the nemunas river steep slopes is not pleasant and save place for walking or cycling (fig. 4). fig. 4. island of nemunas’ river in kaunas, lithuania (photo by i. povilaitienė) european case. the same problems as lost river function in urban space and human life, importance of cars, transport corridors which increasing the gap between society and cities’ rivers existed in europe. however, the consciousness about the role of the river as a perfect recreational urban place in city centre strengthened earlier than in lithuania – in the end of 20th century. people, planners turned to human dimension, the car apotheosis finished. urban planners tried to adapt city spaces, to open natural areas more for pedestrians, cyclists than vehicles. the process of returning the riversides to the people has started. for instance, the river in arhus, denmark, which was converted into street in the 1930s, was changed into open space for people in 1998 and work continued until 2008 (fig. 5, fig. 6). the river and its riversides became the most popular recreational space in the city (gehl 2010). extraordinary riversides’ planning example fitted for human dimension – ljubljana riverside in the old town of ljubljana city centre. this great example shows how river could be used as pleasant and relaxing space in the city centre these days. “due to the very dense mediaeval city structure, the ljubljanica river corridor was the most important open space of the mediaeval urban area” (urbem 2004). moreover, it was a place for bathing in the city centre until 39 the late fifties of the 20th century. according to literature analysis, in 1929, architect jose plecnik (jožef plečnik) managed to fix ljubljana river high vertical concrete walls into human acceptable space for different uses of riverside. though by the beginning of the twenty-first century the river lost its initial recreational function, the streets, and river surroundings were used for vehicles. however, after refurbishment of the banks of the river ljubljanica the river regained its earlier, lost role and its function and ljubljana city got european prize for urban public space competition in 2012 (the european prize… 2013). nowadays there are many spatial uses and activities: bikeways, social events, footpaths etc. moreover, many ramps, terraces, pontoons are made close to river (fig.7). fig. 5. arhus river converted into street in the arhus city centre, 1993 (arhus... 2013) fig. 6. arhus city centre after reopened river, 2008, denmark (arhus... 2013a) fig. 7. ljublijana riverside, slovenia (liublijana… 2013) otherwise, there is no grand revitalization projects focusing attention to the rivers in cities centres. the most important is interpreted new function of the river and the biggest task is to find a key how to fulfil the main goal – to keep cities riversides vital. like paris plage close to seine river or vienna’s the strandbar herrmann place near danube canal where people enjoy river during summertime. for example, the paris plage is opened four weeks from 20 july. the riverside becomes car-free place that time – “a seine-side holiday” space (fig. 8). there is possibility to find everything like being by the seaside: sand, deckchairs and etc. (mairie de paris … 2013). also, many installations and new open beach bars, cafes close to danube canal attract people in vienna (vienna’s canal grande…,2013). fig. 8. paris riverside in summer, france (paris... 2012) furthermore, well known examples are amsterdam, venice and stockholm cities where water never lost its importance and is identity in city core during many ages. in addition, the human-river-urban system exists in harmony and constantly until nowadays. 7. conclusions 1. considering the review of scientific and historical literature, it becomes clear that the role of rivers in city centres is multi-faceted. quite roughly, it can be classified by the main object of interest: a) functional role of the river, b) social role of the river; c) the ecological role of river; d) visual role of the river for the city centre. 2. in the course of history, political and sociocultural events always have influence on urban development and shape of the city. such events also affected the river role for the city centre, as well as influenced the relationships between river and human. depending on that, usually one of the four dimensions (functional, social, ecological or visual) of river role was dominating. 3. according to the literature analysis and empirical researches, the function of the river is not clear in the centres of lithuanian cities nowadays. also, weak social, visual, ecological and identity formation factors led up to the lost role of the river in urban and social context. 4. comparing foreign projects of riversides revitalization with the lithuanian ones, it is obvious that the potential of the river here is untapped and managed insufficiently. all the dimensions of river role (functional, social, ecological and visual) should be developed equally, without overwhelming each other, in order to achieve the 40 most optimal results of riverside regeneration. however the majority of the conceptual ideas are still left in theoretical stage. 5. on the basis of the implemented riversides’ projects abroad the management tendencies of rivers and riversides in the city centre can be distinguished: the river is interpreted as an important axis of city centre with strong visual and ecological role in urban space. also, aspects of sustainability and riversides adapted for social place are the trend of river management nowadays. acknowledgment the research represented in this article was financed by research council of lithuania. agreement no vat – 60/2012. straipsnis parengtas pagal lietuvos mokslo tarybos finansuojamo projekto tyrimų medžiagą. sutarties nr. vat – 60/2012. references alexander ch., ishikawa s., silverstein m., jacobson m., fiksdahlking i., angel sh. 1977. a pattern language: towns, buildings, construction. new york, oxford university press. arhus river converted into street in the arhus city centre, 1993, denmark. 2013. available at: (http://www.advokatgruppen. dk) (accessed 25 june 2013). arhus city centre after reopened river, 2008, denmark. 2013a. available at: (http://www.travelweekly.com) (accessed 25 june 2013). bučas 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(accessed 29 june 2013). vanagas j. 2008. urbanistikos pagrindai [urban basics]. vilnius, technika. vienna’s canal grande – the donaukanal and its attractions. 2011. available at: http://news.viennaresidence.com/blog/ danube-canal (accessed 1 july 2013). vilniaus architektūros parkas. 2008. vilnelės pakrančių sutvarkymo architetktūrinės kūrybinės dirbtuvės 2008 m. available at: http://www.archparkas.vilnius.lt/index.php? 775884593 (accessed 25 may 2012). zavaiša p. 2012. urbanistinio identiteto paieškos vilniuje išnaudojant esamą situaciją [the search for urban identity in vilnius by exploiting the current situation]. in: proceedings of the 6th lithuanian urban forum 2012, vilnius, technika, 66–69. žulkus v. 2002. viduramžių klaipėda [medieval klaipeda]. kaunas, spindulys. received 2013 07 22 accepted after revision 2013 10 10 justina mačiukėnaitė – kaunas university of technology, institute of architecture and construction, centre of territory planning. main research area: urban planning. address: tunelio st. 60, lt-51367 kaunas. tel.: +370 676 48778 e-mail: justina.maciukenaite@gmail.com ingrida povilaitienė – kaunas university of technology, institute of architecture and construction, centre of territory planning. main research area: urban planning. address: tunelio st. 60, lt-51367 kaunas. tel.: +370 609 50483 e-mail: i.lipnickyte@gmail.com 26 darnioji architektūra ir statyba 2013. no. 2(3) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction due to the various useful properties of the lightweight concrete, application of this construction material for the civil engineering purposes becomes more and more popular. lightweight concrete provides low density, which reduces dead loads in constructions and good thermal conductivity, which allows using it in building envelope construction elements as effective thermal insulation and load bearing material. lightweight concrete application in construction reduces building costs, eases construction and has the advantage of being a relatively ‘green’ building material (tommy y. lo et al. 2006). nowadays various lightweight concrete types are invented for using at the construction sites. expanded clay, shale or glass as well as natural porous materials like vermiculite or pumice are typically used as aggregates in the lightweight concrete mixtures. lightweight concrete made from expanded glass granules is one of the latest types of concrete. it is made by incorporating the expanded glass granules into the cement paste matrix. the density of expanded glass could vary from 480 to 1600 kg/m3 (us patent 7695560, 2011). lightweight concrete specimen’s density made with expanded clay aggregate could be 1.6 times higher compared to the concrete specimen made with expanded glass aggregates mechanical and thermal properties of lightweight concrete made from expanded glass girts bumanis*, diana bajare, aleksandrs korjakins institute of materials and structures, faculty of civil engineering, riga technical university, kalku st.1, lv 1658, riga, latvia. *corresponding author: girts.bumanis@rtu.lv http://dx.doi.org/10.5755/j01.sace.2.3.2790 lightweight concrete has become a popular construction material because of several advantages it holds over conventional concrete. lightweight concrete is characterized by good compressive strength, durability and the most important advantages – low density and improved properties of thermal conductivity. typical lightweight concrete aggregates are expanded clay or shale, natural porous materials like vermiculite or pumice. in this research, new type of lightweight aggregates was used, namely, expanded glass granules made from waste glass. loose bulk density, water absorption, material density and material porosity were determined for the expanded glass granules. microporosity of granules was observed and visual inspection of their microstructure was done by using scanning electron microscope (sem). the aim of the study was to identify a relation between mechanical and thermal properties of the lightweight concrete made from expanded glass aggregates. six different concrete mixes with different amount of expanded glass granules and quartz sand were produced. properties of fresh concrete like density and flow table test were tested. flexural and compressive strength as well as density, water absorption and porosity were determined for 28 days old lightweight concrete samples. thermal conductivity of lightweight concrete was determined and relation between thermal and mechanical properties was identified. keywords: expanded glass granules, kightweight concrete, mechanical and thermal properties. (j. jasaitiene et al. 2010). however wasserman and bentur showed that the same aggregate density does not lead to the same concrete strength (wasserman, bentur 1998). traditional lightweight concrete application in construction industry is precast lightweight concrete blocks made from expanded clay aggregates or foamed concrete blocks. castin-place lightweight concrete application in construction industry has become popular in recent years. lightweight concrete made from expanded glass granules provides both casting types. it could be used as pre-casted concrete for production of blocks and cast-in-place lightweight concrete. cast-in-place concrete provides much wider range of concrete application e.g. wall structures, floor thermal insulation and floor and roof screeds. regarding to the recycling of the deconstruction materials several investigations were performed by different researchers. consequently model of recycling lightweight concrete with aggregates containing expanded glass has been proposed. the researchers concluded that recycling of concrete made from lightweight aggregates improves life cycle of the material, and there is no more remaining waste concrete from the lightweight concrete with aggregates containing expanded glass. the materials could be brought 27 back to the life cycle of a product as much as it is possible to innovate production processes and concrete waste material from expanded glass aggregates can be incorporated into the recycling process (d. kralj 2009). because of the low density of expanded glass granules the compressive strength of this material is relatively low. for aggregates with density less than 1000kg/m3, the elastic modulus and the compressive strength of aggregate concrete are strongly affected by the volume fraction of aggregate (y. ke et al. 2009). producers of lightweight expanded glass granules indicate the compressive strength from 0.45−0.55mpa. by incorporating such material in cement matrix concrete compression strength could be limited due to the expanded glass granule compressive strength. lightweight aggregate outer shell thickness, macroporosity and broken grains percentage all affect the aggregate strength (y. ke et al. 2009). the weakest component of lightweight aggregate concrete is not the cement matrix or the interfacial transition zone but the aggregates. so the mechanical performances of lightweight concrete are not only controlled by the cement matrix quality but also the aggregate volume in concrete and the aggregates properties (chi jm 2003). mechanical properties of the lightweight concrete therefore are ensured by the strength of cement matrix and particle packing. there are two basic ways of increasing compressive strength of this composite material. one of them is to change expanded glass granule volume in lightweight concrete mixture. therefore, the strength is obtained by the cement paste volume changes in concrete mixture design. other option is improving of the lightweight concrete mechanical properties by incorporating fine aggregates as sand in the concrete mixture design. the optimal amount of expanded glass aggregate and the corresponding strength of cement mortar matrix can be determined and suitable expanded glass pellet can be chosen for an allotted concrete density and compressive strength (r. nemes 2006). both solutions affect thermal properties of the lightweight concrete. in order to increase the mechanical strength, specimen’s thermal insulation capacity should be slightly reduced because with the increase in density the compressive strength increases faster than the coefficient of thermal conductivity (j. jasaitiene et al. 2010). since sand and cement paste provides high thermal conductivity increasing their volume in lightweight concrete could lead to the thermal conductivity and density increase of the material. to perform a research on the thermal conductivity and compression strength changes due to the expanded glass granule volume and sand incorporation effect, both methods were tested. the amount of sand aggregate in lightweight concrete affects its mechanical and physical properties, such as strength, material density and thermal conductivity. the influence of different sand quantity on the properties of lightweight concrete made from expanded glass aggregates was tested. various lightweight concrete mixtures were prepared to identify relation between mechanical and thermal properties of incorporating various amounts of expanded glass granules and sand in the mixtures including three lightweight concrete mixtures with different expanded glass granule amount and three lightweight concrete mixtures with different amount of sand. mechanical and physical properties were tested and thermal conductivity were observed. 2. methods cement the materials used in this study were commercially available raw materials, cementations materials and admixtures. cem i 42.5n cement was produced in cement production plant cemex in latvia. physical and mechanical properties of cement were tested and results are given in table 1. the chemical composition of cement was tested and results are given in table 2. expanded glass granules expanded glass granules used in this research are commercially available material made by penostek. granule fraction 0/5mm was used in lightweight concrete (fig. 1). fig. 1. expanded glass granules physical and mechanical properties of the expanded glass granules were determined including bulk density, thermal conductivity, compressive strength and water absorption. the bulk density of expanded glass granules were 187-230 kg/m3, the material density was from 250– 280 kg/m3. the water absorption was 120–130 % by dry sample mass. the thermal conductivity of 40 mm thick granule layer was from 0.069–0.071 w/(m·k). grading analysis for expanded glass granules was applied to obtain grading curves for further lightweight concrete mixture design. grading analysis is given in fig. 2. sizes of the granules ranged from 0.25mm to 5.6 mm. since most particles are in range of 0.5–4mm, this is important factor for concrete mixture design, because particle distribution affects lightweight concrete mechanical properties. expanded glass granule pore structure analysis was performed at the faculty of material science and applied chemistry of the riga technical university. mercury intrusion porosimeter pore master 33 (mip) was used to measure pore size distribution in the interval from 0.0064 to 950 µm and porosimeter nova 1200е pore size distribution in the interval from 0.35 to 200 nm. expanded glass granules with fraction 0.5/1mm, 2/4mm and 4/5.6mm were tested. 28 fig. 2. expanded glass granule grading analysis different methods for pore structure investigations were used because mip measures refer mainly to the large capillary porosity while gas sorption method measures the finest pores more accurately, as it is suggested by j. thomas and h. jennings (thomas j. and jennings h. 2009). defined pore radius showed negligible difference between various fractions of expanded glass granules. as it is seen from the table 3, pore radius varies from 0.586 to 3.35 nm for expanded glass granules with fraction 0.5/1 mm and from 0.586 to 0.758 nm for fraction 4/5.6mm. pore volume is 2.056–7.113x10-4 cm3/g for granule fraction 0.5–1mm. table 1. physical and mechanical properties of portland cement cement producer, type setting start time, h setting end time, h compressive strenght, mpa blaine fineness cm2/g particles 45µm sieve, % particles 30µm sieve, % normal consistency, %1d 7d 14d 28d cem i 42.5n 2:52 3:23 14.0 27.7 43.3 53.6 3862 3.5 10.7 27.0 table 2. chemical properties of portland cement cement producer, type compound, % sio2 al2o3 fe2o3 cao mgo so3 na2o k2o tio2 cl cem i 42.5n 19.33 4.26 3.05 61.94 3.19 3.18 0.16 1.26 0.28 0.07 mineralogical compound, % naeq lsf sr ar c3s c2s c3a c4af cemex cem i 42.5n 0.99 101.32 2.65 1.39 63.23 7.75 6.12 9.28 at the same time granules with fraction 4/5.6 mm have volume 1.354–8.636x10-3 cm3/g. it may be concluded that fraction 0.5-1mm have pores with less radius than fraction 4/5.6 mm. pore surface area was 0.2809-4.996 m2/g for granule 0.5/1mm fraction. it is larger for granules with fraction 4/5.6mm ranging from3.031–14.83 m2/g. pore structural analysis results are given in table 3. micro structural analysis of the glass granules has been done by scanning electron microscope tescan mira\ lmu field-emission-gun. pore size and its distribution in expanded glass granules were observed and granule internal and external wall thickness was determined. in addition, energy-dispersive x-ray spectroscopy (edx) was used to determine the chemical characterization of expanded glass granules. overall view of expanded glass granules with fraction 2/4mm is given in fig.3 and fig.4. internal pore diameter varies from 79.58–453.60 µm. pores with smaller diameter are concentrated close to the granule surface while inside the granule pore diameter was from 135.52– 453.60 µm. expanded glass granule external walls have much denser structure than the internal granule structure. external walls consisted of much smaller pores and the thickness of pore walls increased. granule outer shell must provide closed structure to avoid any interaction between granule inside structure and outer environment. due to the brittle structure of granule walls, holes in the granule surface have formed that could lead to the further wall collapse and granule pores could fill with outer substance. table 3. expanded glass granule pore structural analysis granule fraction, mm sample weight, g sample volume, cm3 pore radius, nm pore volume, cm3/g pore surface area, m2/g 0.5–1 0.4264 0.7814 1.550–3.353 2.056–7.113x10-4 0.281–4.996 2–4 0.3705 1.2290 1.700–3.809 1.038–7.533x10-3 2.641–12.230 4–5.6 0.1938 0.7226 1.750–3.758 1.354–8.636x10-3 3.031–14.830 29 content, limestone powder and chemical admixtures for all six mixtures was constant, cement amount being 480 kg, limestone powder amount – 118.8 kg and chemical admixtures – 0.7 kg, 0.02 kg and 0.5 kg respectively. the chemical admixtures were used to ensure workability of lightweight concrete and to control setting time of concrete. first, three mixes with different amount of expanded glass granules were prepared. the chosen amount of expanded glass granules were 300 kg, 400 kg and 500 kg. the amount of necessary water was chosen to ensure lightweight concrete constant workability. due to the high water absorption of expanded glass granules, the amount of water increased proportionally to the amount of expanded glass granules added to the mix. to ensure proper workability and fresh concrete properties, water cement ratio was increased. the water cement ratio for mixture gg300 was 0.81 and it increased to 0.97 for mixture gg500. the other three concrete mixtures were with different sand amount and constant expanded glass granules amount in the mass of cement. the 0.3/2.5 mm sand fraction was used to improve concrete packing and mechanical properties. sand was added in amount of 100, 200 and 300 kg respectively. as it is seen in table 4, with the additional incorporation of sand in the mixture, w/c ratio increased to 0.97 due to the higher amount of fine aggregates to ensure same workability as control mixture. w/c ratio was equal for all three mixtures with incorporated sand. lightweight concrete mixing procedure consisted of dosage of materials and homogenization of dry mixture with electric hand mixer. half of necessary water was added and mixing continued for 1 minute. rest of water was added and mixture was mixed for 1 minute. if additional water was necessary mixing continued for 30 seconds. mixture was cast in prismatic molds 40x40x160mm. for thermal conductivity plates with dimension 300x300x50mm were prepared. molds were filled by half and then evened with trowel, and then rest of mold was filled. fresh lightweight concrete properties were determined. cone slump test and consistence of fresh mortar by flow fig. 3. expanded glass granule inner pore microstructural analysis with sem fig. 4. expanded glass granule outer shell microstructural analysis with sem lightweight concrete mixture composition six different mixtures of lightweight concrete with expanded glass granules were prepared (table 4). cement table 4. lightweight concrete mixture design mixture proportion (by mass) gg300 gg400 gg500 s100 s200 s300 cement cemex cem i 42,5n 480 480 480 480 480 480 limestone powder 118.8 118.8 118.8 118.8 118.8 118.8 chemical admixtures methocel 327 0.7 0.7 0.7 0.7 0.7 0.7 hostapur 0.02 0.02 0.02 0.02 0.02 0.02 na rodanide 0.5 0.5 0.5 0.5 0.5 0.5 expanded glass granules 0/5mm 300 400 500 400 400 400 sand – – – 100 200 300 water 389 440 465 465 465 465 w/c ratio 0.81 0.92 0.97 0.97 0.97 0.97 30 table method were performed for all six concrete mixtures and was tested according to lvs en 12350-2 and lvs en 1015-3. fresh concrete density was determined according to lvs en 12350-6. physical properties of hardened concrete samples like density (lvs en 12390-7:2009), water absorption and thermal conductivity were tested. for water absorption test samples were immersed into water for 72h+2h and weighted. then samples were dried until constant dry mass was obtained. thermal conductivity was performed with heat flow meter instrument lasercomp fox 660 for dry lightweight samples with dimensions of 300x300x50mm. flexural and compressive strength were obtained according to lvs en 1015-11. 3. results lightweight concrete with increased amount of expanded glass granules results of fresh concrete properties for all six mixtures are given in table 5. the w/c ratio was choose according to cone slump of lightweight concrete mixtures gg300 and gg400 was identical – 240 mm. cone slump decreased to 210 mm for mixture gg500due to the higher amount of expanded glass granules added. consistence of fresh mortar (by flow table method) for lightweight concrete mixture gg300 with less granules show the highest flow table result of 185 mm even with lowest w/c ratio. the consistence of mixture with increased amount of granules is reduced to 179 mm for gg400 and 148 mm for gg500. additional amount of water did not increase workability for the chosen mixture composition. w/c ratio for compositions with constant amount of expanded glass granules and different amount of sand was constant. fresh concrete density decreased from 809 kg/m3 to 663 kg/m3for mixtures gg300 and gg400 respectively. density of fresh concrete decreased to 647 kg/m3 for mixture with increased amount of expanded glass granules (gg500). table 5. fresh concrete properties mixture design flow table, mm cone slump, mm fresh concrete density, kg/m3 gg300 185 240 809 gg400 179 240 663 gg500 148 210 647 s100 178 240 656 s200 144 180 797 s300 137 150 837 mechanical properties of lightweight concrete are given in table 6. flexural and compressive strength results indicate that the highest flexural and compressive strength was for the concrete with lowest amount of expanded glass granules (gg300).the increase of expanded glass granules in the mixture from 300 kg to 500 kg decreased the flexural strength of samples from 1.7 to 1.5mpa. compressive strength for mixture gg300 sample was 5.8mpa and decreased to 4.1 and 4.0mpa for samples gg400 and gg500 respectively. strength reduction between gg400 and gg500 was insignificant– only 0.1mpa. table 6. mechanical properties of hardened concrete mixture design flexural strength, 28d, mpa compressive strength, 28d, mpa gg300 1.7 5.8 gg400 1.6 4.1 gg500 1.5 4.0 s100 1.2 3.2 s200 1.6 3.8 s300 1.8 4.5 physical properties of hardened lightweight concrete with increased amount of expanded glass granules are given in table 7. the lightweight concrete density was measured for dry samples and water saturated samples. samples with different expanded glass granule content provide density 685 kg/m3 for mixture gg300, 561 kg/ m3 for mixture gg400 and 558 kg/m3 for mixture gg500. the density of water saturated sample was 905 mkg/m3 for gg300; 767 kg/m3 for gg400 and 753 kg/m3 for gg300. the water absorption of samples increased from 30 % for gg300 to 35 % for gg500. thermal conductivity for samples with different expanded glass granules content decreased from 0.163 w/(m·k) for sample gg300 to 0.141 w/(m·k) for sample gg400. further conductivity improvement was insignificant – 0.140 w/(m·k) for mixture gg500 (table 7). mixtures with increased amount of sand the workability of the lightweight concrete was decreased by adding extra sand to the mixture (table 5). flow table result for mixture s100 was 178mm, for mixture s200 – 144mm and for mixture s300 – 137mm. the cone slump was significantly reduced by incorporation of extra sand. s100 concrete showed similar result to the samples without sand – 240mm (table 5). the cone slump for other concrete mixtures with higher sand content (s200 and s300) decreased to 180 mm and 150 mm respectively. the fresh concrete density depends from extra incorporation of sand. mixture s100 provided fresh concrete density 656 kg/m3, s200 – 797kg/m3 and s300 – 837 kg/m3. lightweight concrete samples with sand incorporation in mixture provided strength increase (table 6). mixture s100 samples provides flexural strength of 1.2mpa; s200 – 1.6mpa and s300 – 1.8mpa. in comparison to the samples without sand incorporation, the flexural strength was higher only for sample s300. compressive strength increase was observed for mixture s100 being 3.2mpa, for mixture s200 – 3.8mpa and for mixture s300 – 4.5mpa. the density of lightweight concrete with incorporated sand increased from 523 to 699 kg/m3 (s100 to s300) (table 7).the density of water saturated samples was from 757 to 913 kg/m3. the density of lightweight concrete increased due to increase of the sand content in concrete 31 mixture. water absorption of samples decreased from 44 to 33 %. due to incorporation of extra sand in the mixture of lightweight concrete thermal conductivity decreases. the thermal conductivity decreased to 0.138 w/(m·k) for mixture s100 compare with sample without sand gg400 (0.141 w/(m·k)). the further increase of sand amount in lightweight concrete mixture provides improvement of thermal conductivity to 0.161 w/(m·k) (s200) and to 0.177 w/(m·k) (s300) (table 7). 4. discussion lightweight concrete made from expanded glass granules provide different mechanical and physical properties affected by chosen concrete mixture design. the chosen quantity of expanded glass granules in concrete mixture provides different material density, water absorption, strength and thermal properties of lightweight concrete. significant difference of lightweight concrete properties between mixture gg300 and gg400 was observed. concrete density decreased from 685 to 561 kg/m3, thermal conductivity – from 0.163 to 0.140w/(m·k), compressive strength – from 5.8 to 4.1mpa. further increase of expanded glass granules amount (see gg500) did not improve concrete properties considerably. it is under question, whether it is economically rentable to use increased quantity of expanded glass granules in mixture design without gaining considerable concrete properties improvement. the different situation was observed for samples with extra sand incorporation in the lightweight concrete mixture. due to extra incorporation of sand in the mixtures material density increased and mechanical properties improved. the density of samples increased from 523 to 651 kg/m3 and water absorption decreased from 44 % to 30 %. thermal conductivity increased from 0.138 to 0.177 w/(m·k) due to extra sand incorporation in the mixture (from 100 to 300 kg). flexural and compressive strength increased from 1.2–1.8mpa and 3.2–4.5mpa respectively. relation between thermal and mechanical properties was identified. from the economical point of view the increase of expanded granules in the mixture (see gg400 and gg500) is not recommended due to the insignificant difference between compressive strength and thermal conductivity results of mixtures gg400 and gg500. mixtures from s100 to s300 provide higher difference in mechanical and thermal properties. the compressive strength improvement and thermal conductivity increase was obtained by the increasing amount of sand in lightweight concrete mixture. 5. conclusions the identified lightweight concrete properties were affected by quantity of expanded glass granule and sand content in mixture design. by changing the quantity of expanded glass granules and the amount of incorporated sand in lightweight concrete mixture different lightweight concrete properties could be obtained. the compressive strength of lightweight concrete with expanded glass granules could vary from 4.0 to 5.8mpa for samples with different quantity of expanded glass granules and from 3.2 to 4.5mpa for lightweight concrete with incorporated sand. thermal conductivity decreases with the increasing amount of expanded glass granules and increases with sand incorporation in lightweight concrete mixture. lightweight concrete made with expanded glass granules could be used as an insulation material with marginally low thermal conductivity and the strength of concrete could vary due to the chosen concrete mixture. the thermal conductivity of lightweight concrete with expanded glass granules is limited by the thermal properties of cement paste and the expanded glass granule properties. this research concludes that further increasement of expanded glass granule amount in mixture design did not provide considerably better concrete thermal conductivity what is important for producers and consumers. by increasing expanded glass amount in lightweight concrete its density could be reduced from 685 to 561 kg/m3 and thermal conductivity – from 0.163 to 0.140 w/(m·k). the constant amount of expanded glass granules and different amount of sand to mixture design provide increaset of concrete density as well as its strength and thermal conductivity properties. the density of lightweight concrete with sand incorporation in the mixture increases from 523 to 651 kg/m3. the increase of thermal conductivity from 0.138 to 0.177 w/(m·k) was significant for samples with higher amount of sand. by defining concrete properties according to its application, the appropriate lightweight concrete mixture design could be chosen. table 7. physical properties of lightweight concrete with expanded glass granules mixture design density (dry), kg/m3 density (water saturated), kg/m3 water absorption, % thermal conductivity, w/(m·k) gg300 685 905 30 0.163 gg400 561 767 32 0.141 gg500 558 753 33 0.140 s100 523 757 44 0.138 s200 645 859 33 0.161 s300 699 913 30 0.177 32 acknowledgment the support of sakret ltd. is acknowledged. references chi jm, huarg r, yang cc, chang jj. effects of aggregate properties on the strength and stiffness of lightweight concrete. cem concr compos 2003; 25 (2): 197–205. http://dx.doi.org/10.1016/s0958-9465(02)00020-3 jasaitiene, j., ivanauskas, e., dauksys, m. 2010. investigation of lightweight concrete with porous aggregates. in: preceeding of the 2nd international conference advanced construction, lithuania, 2010. jennings, h., thomas, j. j. 2009. materials of cement science primer. a final report submitted to the infrastructure technology institute for tea-21 funded projects designated a474 northwestern university, evanston. ke, y., beaucor, a. l., ortola, s., dumontet, h., cabrillac, r. 2009. influence of volume fraction and characteristics of lightweight aggregates on the mechanical properties of concrete. in: construction and building materials 23. p. 2821– 2828. http://dx.doi.org/10.1016/j.conbuildmat.2009.02.038 kralj, d. 2009. experimental study of recycling lightweight concrete with aggregates containing expanded glass. in: process safety and environmental protection 87, p. 267– 273. http://dx.doi.org/10.1016/j.psep.2009.03.003 nemes, r. 2006. lightweight concrete made with expanded glass aggregate. budapest university of technology and economics, budapest. tommy y. lo, tang, w. c., cui, h. z. the effects of aggregate properties on lightweight concrete. building and environment 42. 2007. us patent 7695560. strong, lower density composite concrete building material with foam glass aggregate. 2011. wasserman r, bentur a., interfacial interaction in lightweight aggregate concretes and their influence on the concrete strength. cem concr compos 1996; 14(4): 239–48. received 2012 11 28 accepted after revision 2013 03 18 girts bumanis – b.sc.ing., research assistant at institute of materials and structures, faculty of civil engineering, riga technical university. main research area: lightweight concrete, hp concrete materials, geopolymers. address: kalku iela 1, lv 1658, riga, latvia. tel.: +371 260 62011 e-mail: girts.bumanis@rtu.lv diana bajare – dr.sc.ing., associated professor at the institute of materials and structures, faculty of civil engineering, riga technical university. main research area: hp and uhp concrete, lightweight concrete, geopolymer technology, ceramic, waste recycling in building materials, passive cooling systems, restoration of historical structures and others. address: kalku iela 1, lv 1658, riga, latvia. tel.: +371 296 87085 e-mail: diana.bajare@rtu.lv aleksandrs korjakins – dr.sc.ing., professor at the institute of materials and structures, faculty of civil engineering, riga technical university. main research area: hp and uhp concrete, lightweight concrete, geopolymer technology, ceramic, waste recycling in building materials, passive cooling systems and others. address: kalku iela 1, lv 1658, riga, latvia. tel.: +371 264 22442 e-mail: aleks@latnet.lv 58 the effect of the u value in the energy performance of residential buildings in greece dimitrios bikas, panagiotis chastas* aristotle university of thessaloniki, dept. of civil engineering, laboratory of building construction and building physics, 54124 thessaloniki, greece. *corresponding author: pchastas@civil.auth.gr http://dx.doi.org/10.5755/j01.sace.6.1.5950 according to the european 2012/31/ee directive all new buildings until 31/12/2020 and all new buildings occupied by public authorities until 31/12/2018 should be buildings with nearly zero energy consumption. many countries of the european union have established legislation with provisions for the energy performance of the buildings with a further goal to reach the nearly zero energy consumption building. in greece there is a presence of this attempt from the year 2010 with the regulation of the energy performance in buildings (κενακ, 2010). this was a first attempt for upgrading the energy performance and for establishing the energy inspection of buildings and the relative provisions. in order to achieve the goal and fulfill the requirements of the european legislation a further attempt should be focused in interventions such as lower u value limits in the opaque building elements of the building envelope and windows, in upgrading the energy efficiency of hvac systems and even the use of renewable sources to cover a percentage of the energy requirements of the buildings. this study aims to evaluate the effect of the reduction of the u value of the opaque building elements in the energy requirements and consumption in residential buildings in greece, according the climatic zone that is located, as a step closer to the nearly zero energy consumption building. keywords: nearly zero energy building, residential buildings, energy consumption, u value, opaque building elements. darnioji architektūra ir statyba 2014. no. 1(6) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction greece is one of the one of the 27 state members of the european union that has established commitments towards the nearly zero energy building, such as penalties for energy performance requirement non-compliance and incentives for nearly zero energy buildings and for rent of energy efficient buildings (ó broin, mata, göransson, & johnsson, 2013). this is presented by the greek regulation of energy performance of buildings (kenak) which with the laws 3851/2010 and 3889/2010 regulates the basic principles of operation and management of energy performance and the basic legislation for renewable energy. the regulation of energy performance of buildings aims to improve the energy efficiency of new buildings in greece and of the building stock that is consisted of buildings which have incomplete or inadequate thermal protection. its goal is to reduce the consumption of conventional energy for heating, cooling, air conditioning, lighting and hot water while ensuring the comfort of the interior of buildings. this is achieved with energy efficient design of the building envelope, use of energy efficient building materials and electrical/mechanical equipment, renewable energy sources and chp systems (τοτεε20701−1, 2010). with all these efforts for energy upgrading of buildings in line with the greek legislation in 2013 by law 4122/2013 the european 2012/31/ee directive. its aim is to review periodically the provisions on energy performance of buildings aiming all new buildings until 31/12/2020 and all new buildings occupied by public authorities until 31/12/2018 to be buildings with nearly zero energy consumption. in order to achieve the demanding minimum requirements of the energy performance in buildings, interventions are proposed in the international literature for the energy upgrading of the opaque surface of the building envelope with new lower requirements of the u value and higher thickness of the insulating material or improved window glazing forms (thalfeldta, pikas, kurnitski, & voll, 2013). also another approach is the upgrading of the hvac systems of the building in order to reduce the annual energy consumption with improvements of the efficiency ratio and the automation of the systems. furthermore the use of renewable sources of energy, such as photovoltaic systems, micro-wind turbines etc. is considered in order to cover a percentage of the energy requirements of the building (desideri et al., 2013). 59 this study aims to evaluate the attempts of the energy upgrading of the opaque surface of the building envelope in residential buildings in greece. furthermore is to quantify the effect of the reduction of the u value of the opaque building elements to the annual primary energy consumption by end use and the annual requirements for heating and cooling depending of the climatic zone that is located. 2. methods 2.1. the effect of the u value in the consumption of energy in this analysis was examined the effect of the reduction of the u value in the energy performance of residential buildings and specifically in the annual primary energy consumption by end use and the annual energy requirements for heating and cooling. the typical construction that was examined is provided for tests by iso 13790/2008 (table 1) and takes no account of thermal bridges. table 1. dimensions of construction (iso13790, 2008) building element area (m2) west wall 10.08 window glazing 7.00 north wall 15.40 south wall 15.40 east wall 10.08 floor 19.80 roof-ceiling 19.80 the effect of the u value was examined for the opaque building elements that compose the building envelope of residential buildings in greece (table 2). table 2. maximum value of thermal transmittance (w/m2.k) per climatic zone in greece according to the regulation of energy performance in buildings building elements climatic zone α climatic zone β climatic zone γ climatic zone δ external flat or inclined roof 0.50 0.45 0.40 0.35 external vertical building elements 0.60 0.50 0.45 0.40 windows and doors 3.20 3.00 2.80 2.60 flooring over pilotis 0.50 0.45 0.40 0.35 to calculate the contribution of the reduction of u value in the consumption of energy the maximum u value (table 2), depending on the climatic zone, of all building elements is imported. then the u value of the examined element is changing with a descending step 0.05 w/m2.k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones that greece is divided according to the climatic conditions of each region. 2.2. climatic zones of greece according to the regulation of energy performance in buildings according to kenak greece is divided into four climatic zones depending on the heating degree days of each region. the schematic depiction (fig. 1) defines the regions located in the four climatic zones, from the warmer (climatic zone a) to the coldest (climatic zone δ). in each region of a climatic zone that is located in an altitude over 500 meter, is considered to be in the next colder climatic zone than the one they are originally located. all regions located in climatic zone δ regardless of altitude are included in this zone (τοτεε20701−3, 2010). fig. 1. climatic zones of greece (τοτεε20701−3, 2010) 2.3. software tee kenak the software that was used for this analysis is tee kenak. this software is used to process the energy inspection of buildings and to issue the energy performance certificate. also is used for calculations and the classification that is required for the study of energy efficiency in buildings, boilers and heating and air conditioning systems. it was developed by the group of energy conservation, the institute for environmental research and sustainable development and the national observatory of athens in the framework of the cooperation program with the technical chamber of greece (tee). it was created in accordance with european and national standards, the greek regulation of energy performance of buildings and the associated technical instructions of the technical chamber of greece (totee). the core of the calculations of the software is based on the pre-existing software epa-nr (version 1.7.6.19), which was developed under the european programme intelligent energy of europe, 17th gd eu (eie/04/125/s07.38651), and has been suitably modified to be consistent with the national requirements in greece, as provided in regulation of energy performance in buildings and related technical instructions of the technical chamber of greece. the software uses the monthly method for the calculation of the energy requirements and consumption for heating and cooling as it is defined by iso 13790/2008. this method includes the calculation of the heat transfer by transmission 60 and ventilation, the calculation of the annual energy requirements and energy consumption for heating and cooling and the solar and internal heat gains (iso13790, 2008). for the completeness of this analysis it was considered a theoretical heating system with an oil boiler with an efficiency ratio 0.935, a distribution network of hot water for the transmittance of the heat with an efficiency ratio 0.95, terminal units (radiators) with an efficiency ratio 0.93 and supporting units with power 0.1 w/m2. for the air conditioning system was considered a theoretical cooling system with air-cooled heat pumps with an eer 3.0 and an average monthly coverage of the required cooling energy 0.5, a distribution network with an efficiency ratio 1.0, terminal units with efficiency ratio 0.93 and supporting units with power 0.0 w/m2 (τοτεε20701−1, 2010). 3. results 3.1. vertical building elements of the opaque surface of the building envelope the reduction of the u value (fig. 2) in climatic zone a by 0.01 w/m2.k leads to a reduction in the annual energy requirements for heating 0.518 kwh/m2 and in climatic zone b 0.562 kwh/m2. the same change of the u value leads to a reduction of 1.032 kwh/m2 in zone γ and 1.364 kwh/m2 in zone δ (table 3). fig. 2. reduction of annual energy requirements for heating for the change of u value of the vertical building elements for the four climatic zones fig. 3. reduction of annual energy requirements for cooling for the change of u value of the vertical building elements for the four climatic zones fig. 4. reduction of annual primary energy consumption by end use for the change of u value of the vertical building elements for the four climatic zones the annual energy requirements for cooling appear to have small changes in all four climatic zones between the original and the final u value (fig. 3). a decrease 0.075 kwh/m2 is observed in climatic zone a and a decrease 0.073 kwh/m2 in climatic zone b. an increase 0.011 kwh/m2 is observed in climatic zone γ and 0.057 kwh/m2 in climatic zone δ for the reduction of the u value by 0.01 w/m2.k (table 3). the reduction of the u value in climatic zone a (fig. 4) by 0.01 w/m2.k leads to a reduction in the annual primary energy consumption by end use 0.733 kwh/m2 and in climatic zone b 0.793 kwh/m2. in climatic zones γ and δ the same change of the u value leads to a reduction of 1.331 kwh/m2 in zone γ and 1.725 kwh/m2 in zone δ (table 3). table 3. effect of the reduction of the u value by 0.01 w/m2.k to the annual energy requirements for heating and cooling and the annual primary energy consumption by end use vertical building elements reduction of u value 0.01 w/m2.k climatic zone a climatic zone b climatic zone γ climatic zone δ annual primary energy consumption by end use (kwh/m2) -0.733 -0.793 -1.331 -1.725 annual energy requirements for heating (kwh/m2) -0.518 -0.562 -1.032 -1.364 annual energy requirements for cooling (kwh/m2) -0.075 -0.073 +0.011 +0.057 evaluation as it is observed (fig. 5) the reduction of the energy requirements for heating follows about the same change as the effect of the reduction of the u value between the four climatic zones and for a point of reference the values of climatic zone a. from the transaction from climatic zone a to b the changes in these parameters are minor with a percentage 6.6–8.5 %. from climatic zone a to γ a difference is observed of 99.4–105.6 % and from climatic zone a to δ 163.4–173.2 %. 61 fig. 5. the reduction of the u value and of the annual energy requirements for heating between the four climatic zones between the reduction in the primary energy consumption by end use and the effect of the u value a significant difference is observed in the percentage change (fig. 6). the percentage change of the effect of the reduction of the u value from climatic zone a to β is 8.2 %, from zone a to γ 81.7 % and from zone a to δ 135.5. the average percentage change in the reduction of the primary energy consumption by end use from climatic zone a to b is 2.9 %, from zone a to γ is 56.5 % and from zone γ to δ is 85.8 %. this can be explained by the influence of a number of other parameters to the final calculation of the primary energy by end use such as the technical parameters of the heating and cooling system (efficiency ratio, eer, automation of hvac systems etc.) and the indicators used for the calculation of the contribution of the form of energy source. fig. 6. the reduction of the u value and of the annual primary energy consumption by end use between the four climatic zones 3.2. building element flooring over pilotis the reduction of the u value in climatic zone a (fig. 7) by 0.01 w/m2.k leads to a reduction in the annual energy requirements for heating 0.227 kwh/m2 and in climatic zone b 0.246 kwh/m2. in climatic zones γ and δ the same change of the u value leads to a reduction of 0.444 kwh/m2 in zone γ and 0.574 kwh/m2 in zone δ (table 4). in the annual energy requirements for cooling (fig. 8) an increase 0.024 kwh/m2 is observed in climatic zone a, in climatic zone b 0.025 kwh/m2, in climatic zone γ 0.045 kwh/m2 and in climatic zone δ 0.058 kwh/m2 for a reduction of the u value by 0.01 w/m2.k (table 4). fig. 7. reduction of annual energy requirements for heating for the change of u value of the building element flooring over pilotis for the four climatic zones fig. 8. reduction of annual energy requirements for cooling for the change of u value of the building element flooring over pilotis for the four climatic zones fig. 9. reduction of annual primary energy consumption by end use for the change of u value of the building element flooring over pilotis for the four climatic zones the reduction of the u value in climatic zone a by 0.01 w/m2×k leads to a reduction in the annual primary energy consumption by end use (fig. 9) 0.293 kwh/m2 and in climatic zone b 0.320 kwh/m2. in climatic zones γ and δ the same change of the u value leads to a reduction of 0.550 kwh/m2 in zone γ and 0.706 kwh/m2 in zone δ (table 4). 62 table 4. effect of the reduction of the u value by 0.01 w/m2.k to the annual energy requirements for heating and cooling and the annual primary energy consumption by end use flooring over pilotis reduction of u value 0.01 w/m2.k climatic zone a climatic zone b climatic zone γ climatic zone δ annual primary energy consumption by end use (kwh/m2) -0.293 -0.320 -0.550 -0.706 annual energy requirements for heating (kwh/m2) -0.227 -0.246 -0.444 -0.574 annual energy requirements for cooling (kwh/m2) +0.024 +0.025 +0.045 +0.058 evaluation as it is observed (fig. 10) the reduction of the energy requirements for heating follows about the same change as the effect of the reduction of the u value between the four climatic zones and for a point of reference the values of climatic zone a. from the transaction from climatic zone a to b the changes in these parameters are minor with a percentage 0.0–8.2 %. from climatic zone a to γ a difference is observed of 86.0–95.1 % and from climatic zone a to δ 140.7–152.2 %. fig. 10. the reduction of the u value and of the annual energy requirements for heating between the four climatic zones fig. 11. reduction of annual primary energy consumption for the change of u value of the vertical building elements for the four climatic zones between the reduction in the primary energy consumption by end use and the effect of the u value a significant difference is observed in the percentage change (fig. 11). the percentage change to the effect of the reduction of the u value from climatic zone a to β is 9.0 %, from zone a to γ 87.5 % and from zone a to δ 140.8 %. the average percentage change in the reduction of the primary energy consumption by end use from climatic zone a to b is 0.0 %, from zone a to γ is 48.8 % and from zone γ to δ is 74.4 %. 3.3. building element roof the reduction of the u value (fig. 12) in climatic zone a by 0.01 w/m2.k leads to a reduction in the annual energy requirements for heating 0.190 kwh/m2 and in climatic zone b 0.209 kwh/m2.in climatic zones γ and δ the same change of the u value leads to a reduction of 0.373 kwh/m2 in zone γ and 0.510 kwh/m2 in zone δ (table 5). fig. 12. the reduction of the u value and of the annual energy requirements for heating of the building element roof between the four climatic zones in the annual energy requirements for cooling (fig. 13) a decrease 0.094 kwh/m2 is observed in climatic zone a, in climatic zone b 0.082 kwh/m2, in climatic zone γ 0.046 kwh/m2 and in climatic zone δ 0.026 kwh/m2 for a reduction of the u value by 0.01 w/m2.k (table 5). fig. 13. reduction of annual energy requirements for cooling for the change of u value of the building element roof for the four climatic zones the reduction of the u value in climatic zone a by 0.01 w/m2.k leads to a reduction in the annual primary 63 energy consumption by end use (fig. 14) 0.300 kwh/m2 and in climatic zone b 0.323 kwh/m2. in climatic zones γ and δ the same change of the u value leads to a reduction of 0.508 kwh/m2 in zone γ and 0.671 kwh/m2 in zone δ (table 5). fig. 14. reduction of annual primary energy consumption by end use for the change of u value of the building element roof for the four climatic zones table 5. effect of the reduction of the u value by 0.01 w/m2.k to the annual energy requirements for heating and cooling and the annual primary energy consumption by end use roof inclined or flat reduction of u value 0.01 w/m2.k climatic zone a climatic zone b climatic zone γ climatic zone δ annual primary energy consumption by end use (kwh/m2) -0.300 -0.323 -0.508 -0.671 annual energy requirements for heating (kwh/m2) -0.190 -0.209 -0.373 -0.510 annual energy requirements for cooling (kwh/m2) -0.094 -0.082 -0.046 -0.026 evaluation between the reduction in the energy requirements for heating and the effect of the u value (fig. 15) a significant difference is observed in the percentage change. the percentage change to the effect of the reduction of the u fig. 15. the reduction of the u value and of the annual energy requirements for heating between the four climatic zones value from climatic zone a to β is 9.8 %, from zone a to γ 96.2 % and from zone a to δ 168.0 %. the average percentage change in the reduction of the energy requirements from climatic zone a to b is 0.0 %, from zone a to γ is 84.9 % and from zone γ to δ is 137.9 %. fig. 16. reduction of annual primary energy consumption by end use for the change of u value of the building element roof for the four climatic zones between the reduction in the primary energy consumption by end use and the effect of the u value a significant difference is observed in the percentage change (fig. 16). the percentage change to the effect of the reduction of the u value from climatic zone a to β is 7.6 %, from zone a to γ 69.2 % and from zone a to δ 123.5 %. the average percentage change in the reduction of the primary energy consumption by end use from climatic zone a to b is 0.0 %, from zone a to γ is 49.6 % and from zone γ to δ is 75.1 %. 4. discussion in the typical construction that was examined in this study the reduction of the u value appears to have significant influence in all the opaque building elements. the greater reduction in the energy requirements and primary energy consumption by end use is observed in the vertical building elements in all four climatic zones. this could be explained from the fact that they cover a significant percentage of the area of the building envelope. this reduction in the other building elements is about 50 % of the reduction of the vertical building elements. the reduction increases during the transaction from climatic zone a to climatic zone δ. between climatic zones a and b the change in the reduction of the energy requirements for heating for the descending step of the u value is about 0.0–9.8 %. but in climatic zone γ an increase 81.7–96.2 % and in climatic zone δ 135.5–168.0 % is observed in all the opaque building elements of the building envelope. in the primary energy consumption by end use the vertical building elements appears to have twice the reduction of the other building elements in all climatic zones. this reduction increases from climatic zone a to b about 7.6–9.0 %, from b to γ 69.2–87.5 % and from γ to δ 123.5–140.8 % in all the building elements. this lower effect of the u value in the primary energy by end use could be explained by the influence of a number of other 64 parameters to the final calculation of the primary energy such as the technical parameters of the heating and cooling system (efficiency ratio, eer, automation of hvac systems etc.) and the indicators used for the calculation of the contribution of the form of energy source. the effect of the u value in the change of energy requirements for cooling is about 90.0 % lower than the energy requirements for heating and the primary energy consumption by end use. an increase or a decrease is observed depending on the building element and the climatic zone. from climatic zone γ to δ an increase is mainly observed however its importance is minor due to the from the fact that is lower up to 90.0 % than the annual requirements for heating which overrides this difference and lead to a reduction of the annual primary energy consumption by end use. this increase could be explained from the fact that the reduction of the u value prevents outer temperatures, which are lower than climatic zones a and b, to be transferred in the internal of the building and reduce its temperature. a reduction of the u value of 60 % from the maximum u value of all opaque building elements, in the typical construction of this study, leads to reduction 29.2 % in the annual primary energy consumption by end use in climatic zone a, in climatic zone b 27.9 %, in zone γ 27.9 % and in climatic zone δ 27.5 %. 5. conclusions the reduction of the u value of the opaque building elements of the building envelope is a first approach for the energy upgrading of buildings and a step closer to the buildings with nearly zero energy consumption. in all climatic zones the reduction of the u value leads to a significant reduction in the primary energy consumption by end use and in the energy requirements for heating. with the reduction of their u value a significant reduction to the energy requirements for heating is observed, with an increase from climatic zone α to δ between 137,9 % and 173,2 %, depending on the building element. the same trend is observed in primary energy consumption by end use with an increase from climatic zone α to δ between 74,4 % and 85,8 %. the reduction of the energy requirements for cooling seems to be minor in relation to the energy requirements for heating and the primary energy consumption. these reductions could lead up to 30 % lower energy consumption in residential buildings as a result of this study. however there is a distance from the final goal of the nearly zero energy building as the increase of the thickness of the insulating material should be considered in a cost optimal way. as a result other interventions and approaches could be considered, such as the effect of thermal transmittance of the windows of residential buildings in the energy consumption and the air tightness of the building. windows with energy effective materials or increased number of window glazing could also be considered. furthermore the upgrading of the efficiency of the hvac systems and their automations would probably lead to a reduction of the energy consumption. another approach that could be considered in this evaluation is the use of photovoltaic systems for the reduction of the energy consumption or other renewable energy sources and the use of solar panels for the reduction of the energy requirements for hot water. on the way to meet the requirements of the nearly zero energy building only a combination of solutions, in a cost optimal way, would give the expected result. acknowledgment this study was carried out for a diploma thesis in the msc program “environmental protection and sustainable development” of the department of civil engineering of aristotle university of thessaloniki. this paper was completed as a part of this msc program and co-financed by the act “scholarships program ssf (state scholarships foundation/iky) with an individualized assessment process of the academic year 2012-2013” from resources of the operational program “education and lifelong learning”, of the european social fund (esf) and the nsrf (20072013). references desideri u., arcioni l., leonardi d., cesaretti l., perugini p., agabitini e.evangelisti n., 2013. design of a multipurpose “zero energy consumption” building according to european directive 2010/31/eu: architectural and technical plants solutions. energy, elsevier, vol. 58, 157–167. iso13790, 2008. energy performance of buildings calculation of energy use for space heating and cooling. ó broin e., mata é., göransson a., johnsson f., 2013. the effect of improved efficiency on energy savings in eu-27 buildings. energy, elsevier, vol. 57, 134–148. thalfeldta m., pikas e., kurnitski j., voll h., 2013. facade design principles for nearly zero energy buildings in a cold climatic. energy and buildings, elsevier, vol. 67, 309–321. http://dx.doi.org/10.1016/j.enbuild.2013.08.027 κενακ, 2010. αριθ. δ6/β/οικ. 5825. ΄εγκριση κανονισμού ενεργειακής απόδοσης κτιρίων εφημερίς της κυβερνήσεως της ελληνικής δημοκρατίας, 5333–5356, [regulation of energy performance in buildings]. τοτεε 20701−1. 2010. αναλυτικές εθνικές προδιαγραφές παραμέτρων για τον υπολογισμό της ενεργειακής απόδοσης κτιρίων και την έκδοση του πιστοποιητικού ενεργειακής απόδοσης. εφημερίς της κυβερνήσεως της ελληνικής δημοκρατίας, vol. 1387, 21435–21442. [technical instructions of the technical chamber of greece detailed national standards and parameters for calculating the energy performance of buildings and issuing energy performance certificate]. τοτεε 20701−3, 2010. κλιματικά δεδομένα ελληνικών περιοχών. εφημερίς της κυβερνήσεως της ελληνικής δημοκρατίας vol. 1387, 21435–21442. [technical instructions of the technical chamber of greece climatic data of greek regions]. received 2013 12 16 accepted after revision 2014 02 08 65 dimitrios bikas – professor, director laboratory of building construction and building physics, vice chairman of the dept. of civil engineering. main research area: building construction, building physics, energy efficiency of buildings, sustainable building. address: aristotle university of thessaloniki, dept. of civil engineering, laboratory of building construction and building physics, 54124 thessaloniki, greece. tel.: +30 2310 995763, +30 6972096311 e-mail: bikasd@civil.auth.gr panagiotis chastas – civil engineer and msc “environmental protection and sustainable development” graduate, school of civil engineering of aristotle university of thessaloniki (auth). main research area: life cycle analysis and energy performance in residential buildings. address: aristotle university of thessaloniki, dept. of civil engineering, laboratory of building construction and building physics, 54124 thessaloniki, greece. tel.: +30 6976500057 e-mail: pchastas@civil.auth.gr 5 journal of sustainable architecture and civil engineering 2020/1/26 *corresponding author: ausra.mlinkauskiene@ktu.lt bim integration possibilities in different study cycles of architecture study programme received 2019/06/22 accepted after revision 2019/12/15 journal of sustainable architecture and civil engineering vol. 1 / no. 26 / 2020 pp. 5-17 doi 10.5755/j01.sace.26.1.22393 bim integration possibilities in different study cycles of architecture study programme jsace 1/26 http://dx.doi.org/10.5755/j01.sace.26.1.22393 aušra mlinkauskienė*, laura jankauskaitė-jurevičienė kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania per christensen via architectural technology and construction management chr. m. østergaards vej 4, dk 8700 horsens, demmark luca finocchiaro, gabriele lobaccaro department of architecture and technology, norwegian university of science and technology, alfred getz vei 3 _ no 7491 trondheim, norway european countries are developing or implementing policies that promote or require the use of information modelling in the architecture, engineering, construction and manufacture sectors. the integration of building information modelling (bim) to these sectors includes social, economic, political, legal and other aspects. this is why the implementation of bim requires an integrated and broad approach that includes not only the bim implementation and development strategy in designing companies but also in the field of education and professional training. the article discusses the potential of integrating bim in different study programs and the possibilities of international cooperation in interdisciplinary bim projects. the different levels of bim will be explored in connection to different curricula. particular attention is paid to the compatibility and applicability of design and innovative technology solutions using bim methodology and the development of co-operation between higher education institutions in the nordic region [1]. the aim of this paper is to carry out a comparative analysis and present the integration model of building information modeling (bim) into the architecture programmes in different study cycles based on the example of nordic countries. objectives: _ to provide bim use opportunities in 3 years bachelor level based on engineeering architecture study programme of via university college; _ to provide bim use opportunities in 5 years integrated studies based on architecture studies programme of kaunas university of technology; _ to provide bim use opportunities in the 2 years master of science program in sustainable architecture at the norwegian university of science and technology; _ to perform comparative analysis between different countries and different study cycles; _ to provide a possible model for integration of the international bim project in different study cycles. keywords: building information modelling (bim), architecture studies. journal of sustainable architecture and civil engineering 2020/1/26 6 bim use opportunities in bachelor studies introduction architecture studies shall be balanced between the theoretical and practical aspects of architectural training and shall ensure the acquisition of: an ability to create architectural designs that satisfy both aesthetic and technical requirements; an adequate knowledge of the history and theories of architecture and the related arts, technologies and human sciences; a knowledge of the fine arts as an influence on the quality of architectural design; an adequate knowledge of urban design, planning and the skills involved in the planning process; an understanding of the relationship between people and buildings, and between buildings and their environment, and of the need to relate buildings and the spaces between them to human need and scale; an understanding of the profession of architecture and the role of the architect in society, in particular in preparing briefs that take account of social factors; an understanding of the methods of investigation and preparation of the brief for a design project; an understanding of the structural design, constructional and engineering problems associated with building design; an adequate knowledge of the physical problems and technologies and of the function of buildings so as to provide them with internal conditions of comfort and protection against the climate; the necessary design skills to meet building users requirements within the constraints imposed by cost factors and building regulations; an adequate knowledge of the industries, organisations and procedures involved in translating design concepts into buildings and integrating plans into overall planning [2]. nowadays it is very important for an architect to adapt today’s technologies and to be able to work in a team with engineering specialties. this is possible to do with bim technologies. in this definition, technological processes occupy an important place in architectural studies. even some of the above are focused on digitization and technological processes: an ability to create architectural designs that meet both aesthetic and technical requirements; an understanding of the structural design, constructional and engineering problems associated with building design; adequate knowledge of the physical problems and technologies and the function of buildings so as to provide them with internal comfort and protection conditions against the climate; necessary design skills to meet building user requirements within the limits imposed by cost factors and building regulations; an adequate knowledge of the industries, organizations and procedures involved in translating design concepts into buildings and integrating plans into general planning. architectural technology and construction management programme of via university college in accordance with the rules for the study programmes, cf. ministerial order no. 715 of 7 july 2009 on the professional bachelor programme in architectural technology and construction management, the academy profession programme in construction technology and the academy profession programme in surveying and mapping, parts of the discipline-specific contents of the three programmes are common, as illustrated in fig.1 [3]. the architectural technology and construction management programme has duration of 3½ years and is made up of seven semesters totalling 210 ects, which are composed of a number of compulsory and elective programme elements, including internship and bachelor project. the compulsory programme elements are common to all programmes offered in denmark. however, the individual institution has defined the elective programme elements. a further description of these appears from the common and institution-specific part, respectively. the architectural technology and construction management programme is also offered in danish. the danish title is bygningskonstruktøruddannelsen. the distribution of ects points on compulsory and elective programme elements, including internship and bachelor project, is illustrated in the following fig. 2 [3]. bim is an integrated approach to digitize the construction process. throughout the building’s lifecycle, from conception to demolition, the digital building models will be the focal point for all con7 journal of sustainable architecture and civil engineering 2020/1/26 struction activities of the project and the cooperation between the different parties. bim is both a model and a methodology. bim means closer cooperation between all parties and branching out to each player participating in a project. the implementing network for digital construction was formed in 2005 and consists of the 7 largest organizations in the construction industry in denmark. the network was formed to carry out awareness and implementation of digital construction in the construction industry and was until 28.02.2011 responsible for development, content and operation of the portal www.detdigitalebyggeri.dk the association “bips” took over the operation of the portal first march 2011. since the beginning and up until now there have continuously been taken initiatives to meet those, in the legislation, increased demand for digitization, so that the development is also reflected in the classroom. bim implementation on the programme is based on bim guides developed by pennsylvania state university, with its bim applications (bim uses). there will be variations in relation to teaching depending on the actual location and in relation to the teaching of the danish and international classes. fig. 2 the compulsory and elective elements of the architectural technology and construction management programme fig. 1 programme structure 2 constructional and engineering problems associated with building design; adequate knowledge of the physical problems and technologies and the function of buildings so as to provide them with internal comfort and protection conditions against the climate; necessary design skills to meet building user requirements within the limits imposed by cost factors and building regulations; an adequate knowledge of the industries, organizations and procedures involved in translating design concepts into buildings and integrating plans into general planning. bim use opportunities in bachelor studies architectural technology and construction management programme of via university college in accordance with the rules for the study programmes, cf. ministerial order no. 715 of 7 july 2009 on the professional bachelor programme in architectural technology and construction management, the academy profession programme in construction technology and the academy profession programme in surveying and mapping, parts of the discipline-specific contents of the three programmes are common, as illustrated in figure 1 [3]: figure 1. programme structure the architectural technology and construction management programme has duration of 3½ years and is made up of seven semesters totalling 210 ects, which are composed of a number of compulsory and elective programme elements, including internship and bachelor project. the compulsory programme elements are common to all programmes offered in denmark. however, the individual institution has defined the elective programme elements. a further description of these appears from the common and institution-specific part, respectively. the architectural technology and construction management programme is also offered in danish. the danish title is bygningskonstruktøruddannelsen. the distribution of ects points on compulsory and elective programme elements, including internship and bachelor project, is illustrated in the following figure 2 [3]: 2 constructional and engineering problems associated with building design; adequate knowledge of the physical problems and technologies and the function of buildings so as to provide them with internal comfort and protection conditions against the climate; necessary design skills to meet building user requirements within the limits imposed by cost factors and building regulations; an adequate knowledge of the industries, organizations and procedures involved in translating design concepts into buildings and integrating plans into general planning. bim use opportunities in bachelor studies architectural technology and construction management programme of via university college in accordance with the rules for the study programmes, cf. ministerial order no. 715 of 7 july 2009 on the professional bachelor programme in architectural technology and construction management, the academy profession programme in construction technology and the academy profession programme in surveying and mapping, parts of the discipline-specific contents of the three programmes are common, as illustrated in figure 1 [3]: figure 1. programme structure the architectural technology and construction management programme has duration of 3½ years and is made up of seven semesters totalling 210 ects, which are composed of a number of compulsory and elective programme elements, including internship and bachelor project. the compulsory programme elements are common to all programmes offered in denmark. however, the individual institution has defined the elective programme elements. a further description of these appears from the common and institution-specific part, respectively. the architectural technology and construction management programme is also offered in danish. the danish title is bygningskonstruktøruddannelsen. the distribution of ects points on compulsory and elective programme elements, including internship and bachelor project, is illustrated in the following figure 2 [3]: http://www.detdigitalebyggeri.dk http://www.detdigitalebyggeri.dk journal of sustainable architecture and civil engineering 2020/1/26 8 bim uses progression through the semesters. the progression of bim uses through the constructing architect courses´ semesters happens via 5 focus areas: 1. basic modelling and extraction from drawings; 2. quantity take-offs; 3. utilization of the properties data, incl. establishment of own properties data; 4. visualization; 5. integration with other software applications (hereafter called programs). bim use opportunities in 5 years integrated studies based on architecture studies programme of kaunas university of technology structure of the architecture study programme. the aim of the architecture study programme, taught at the faculty of civil engineering and architecture of ktu is: to provide the knowledge to understand the socio-cultural and technological content of architecture, to express it through architectural artistic means, to develop the ability to identify and solve architectural problems by applying interdisciplinary knowledge, to develop research and design skills and the ability to visualize architectural solutions. the duration of the study programme in ktu is five years and it meets the new requirements of the directive. practical professional work oriented subjects take more than 50 credits of the architectural design and urban planning programme. this corresponds to the need to strengthen the practical part of preparation of architects, established in the directive, and informally it also meets the requirement to make architecture the component of the studies. so far, this requirement was meet in programmes of other universities of lithuania by including design and supporting, serving modules. as the programme is taught at the faculty of civil engineering and architecture, it is beneficial for group work of the future architects and civil engineers. base on the presented information it can be stated that the content of architecture integrated studies provides students with the necessary theoretical knowledge and practical skills, specified in directive 2013/55/eu of the european parliament and of the council of 20 november 2013, as well as programmes of higher education of this field in other countries of the european union. the five year architecture study programme consists of the following parts: 1) design based, 2) research based, 3) practice based, 4) test based (according to students’ needs), 5) general required. by the university selected parts study programme consist following parts: 1) general subjects of university studies, 2) subjects of the study field, 3) practice, 4) final degree project, 5) optional subjects (according to students’ needs). the total scope of the programme of architectural studies is 300 cr., from 15 cr. or 5 percent of the entire scope of the study programme is allocated to general university study subjects, 225 cr. or 75 percent – to subjects of the study field, practice is 18 cr. or 6 percent., and the final degree project consists of 30 cr. or 10 percent of the entire scope of the study programme. the optional subjects are given 12 cr. or 4 percent of the entire scopes of the study programme. the chronological order of individual subjects of the study programme in the semester is based on the necessity of preparation for studies of that subject. practical design modules and theoretical, technological modules are placed in accordance with the principle of consistency, starting with improvement of knowledge from simple analysis of architectural object and submission of design proposals – a mono-functional object, and later, obtaining professional knowledge for design of a multifunctional architectural object. during the 7th and 8th semesters students gain knowledge on both the level of static design (architectural), and formation of the environment (urbanistic), and will receive the architect’s qualification degree after finishing the final degree project [4]. the programme based on principles of interdisciplinary, creativity and innovation, critical thinking and problem solving ensures adaptation of graduates in the ever-changing and diverse multicultural, technological, social contexts. all of this determines its uniqueness and appeal. 9 journal of sustainable architecture and civil engineering 2020/1/26 the principles of formation of the study programme and its learning outcomes: _ design and problem tasks oriented environment: the study programme is based on design tasks, the developed critical thinking, problem tasks and other concepts of modern educational sciences. students are encouraged to work in groups to develop critical thinking, organizational skills and to seek creative solutions to real existing architectural problems and challenges. _ the didactical system of the study programme is based on the approach that the lecturer must only be there for support, helping find various ways to solve problems, instead of an omniscient authority. each study module must find its most appropriate and efficient learning/teaching methods. _ interdisciplinary, creativity, critical thinking and developed imagination must conclude the basis of the study programme. students of various years and fields, as well as students of different modules must be encouraged to work together to find innovative ways to solve practical problems. _ the study programme implements the principle, based on good knowledge of the needs of the client and technological solutions – “architectural form follows content”. in this respect the programme in ktu is different from other programmes, in which the artistic architectural expression is the priority. adapting the architecture study program to the needs of nowadays, special attention has to be given to the integration of bim in study process. bim integration capabilities by 3 focus areas: 1. integration to elective subjects; 2. the development of design based subjects; 3. cooperation with praxis subjects (join project). bim implementation to the elective subjects based on software development. students have possibilities to learn specific programs, which are integrated to the modules: cad/cam fabrication, fig. 3 structure of the ktu architectural study programme 4 design of a multifunctional architectural object. during the 7th and 8th semesters students gain knowledge on both the level of static design (architectural), and formation of the environment (urbanistic), and will receive the architect’s qualification degree after finishing the final degree project [4]. figure 3. structure of the ktu architectural study programme the programme based on principles of interdisciplinary, creativity and innovation, critical thinking and problem solving ensures adaptation of graduates in the ever-changing and diverse multicultural, technological, social contexts. all of this determines its uniqueness and appeal. the principles of formation of the study programme and its learning outcomes:  design and problem tasks oriented environment: the study programme is based on design tasks, the developed critical thinking, problem tasks and other concepts of modern educational sciences. students are encouraged to work in groups to develop critical thinking, organizational skills and to seek creative solutions to real existing architectural problems and challenges.  the didactical system of the study programme is based on the approach that the lecturer must only be there for support, helping find various ways to solve problems, instead of an omniscient authority. each study module must find its most appropriate and efficient learning/teaching methods.  interdisciplinary, creativity, critical thinking and developed imagination must conclude the basis of the study programme. students of various years and fields, as well as students of different modules must be encouraged to work together to find innovative ways to solve practical problems.  the study programme implements the principle, based on good knowledge of the needs of the client and technological solutions – “architectural form follows content”. in this respect the programme in ktu is different from other programmes, in which the artistic architectural expression is the priority. adapting the architecture study program to the needs of nowadays, special attention has to be given to the integration of bim in study process. bim integration capabilities by 3 focus areas: 1. integration to elective subjects; 2. the development of design based subjects; 3. cooperation with praxis subjects (join project). bim implementation to the elective subjects based on software development. students have possibilities to learn specific programs, which are integrated to the modules: cad/cam fabrication, web looping, parametric animation and installation, virtual reality generation and activation. bim implementation to the design based subjects based on adaptation in speciality. student can get basics about bim process in journal of sustainable architecture and civil engineering 2020/1/26 10 web looping, parametric animation and installation, virtual reality generation and activation. bim implementation to the design based subjects based on adaptation in speciality. student can get basics about bim process in architectural design subjects: architectural experiment, architectonic development, urban planning, research project and final degree project. and 3th focus area for bim implementation to the architecture study programme based on praxis subjects, especially join project. this multidisciplinary subject joins students with different specialities: architects, civil engineers, automatic engineers, urban engineers, building engineers and electrical engineers. main aim of this subject: to provide a better understanding of the design process with bim, learn to work in team and defend their professional interest in the project. sustainable architecture programme of norvegian science and technology university the msc program in sustainable architecture at ntnu aims at educate and train building professionals in learning, using and developing competitive methods and solutions of bioclimatic architecture towards reduction of ghg emissions of the built environment. learning outcomes of the program have been defined in accordance with the united nations framework convention on climate change according to which greenhouse gas emissions concentration in the atmosphere should be significantly limited if we want to “prevent dangerous anthropogenic interference with the climate system”. scientific knowledge of different nature is used, throughout the two years of studies, as the platform for the architectural design of buildings characterized by low environmental impact. cooperation between architects and engineers represents, in this regard, a fundamental key aspect. the program, moreover, is based on the assumption that multidisciplinary collaboration cannot be thought on a theoretical basis but can be learned only “learning by doing” through practical experiences. the program is therefore open to students with both background, architecture and engineer and they are usually balanced in number and nationality. the curriculum of the msc in sustainable architecture is structured around three main concerns related to the environmental impact of the built environment (climate and environmental performance of buildings; materials’ durability and environmental impact; integrated energy design processes and energy systems). in each semester, students acquire specific knowledge and relevant competences for lowering ghg emissions of buildings. the first semester, based on a tight comparison between climatic data and human comfort requirements, focuses on passive bioclimatic strategies for energy efficiency and performance-driven design processes. the second semester bim use opportunities in master studies fig. 4 structure of the msc program in sustainable architecture at ntnu 5 architectural design subjects: architectural experiment, architectonic development, urban planning, research project and final degree project. and 3th focus area for bim implementation to the architecture study programme based on praxis subjects, especially join project. this multidisciplinary subject joins students with different specialities: architects, civil engineers, automatic engineers, urban engineers, building engineers and electrical engineers. main aim of this subject: to provide a better understanding of the design process with bim, learn to work in team and defend their professional interest in the project. bim use opportunities in master studies sustainable architecture programme of norvegian science and technology university the msc program in sustainable architecture at ntnu aims at educate and train building professionals in learning, using and developing competitive methods and solutions of bioclimatic architecture towards reduction of ghg emissions of the built environment. learning outcomes of the program have been defined in accordance with the united nations framework convention on climate change according to which greenhouse gas emissions concentration in the atmosphere should be significantly limited if we want to “prevent dangerous anthropogenic interference with the climate system”. scientific knowledge of different nature is used, throughout the two years of studies, as the platform for the architectural design of buildings characterized by low environmental impact. cooperation between architects and engineers represents, in this regard, a fundamental key aspect. the program, moreover, is based on the assumption that multidisciplinary collaboration cannot be thought on a theoretical basis but can be learned only “learning by doing” through practical experiences. the program is therefore open to students with both background, architecture and engineer and they are usually balanced in number and nationality. the curriculum of the msc in sustainable architecture is structured around three main concerns related to the environmental impact of the built environment (climate and environmental performance of buildings; materials’ durability and environmental impact; integrated energy design processes and energy systems). in each semester, students acquire specific knowledge and relevant competences for lowering ghg emissions of buildings. the first semester, based on a tight comparison between climatic data and human comfort requirements, focuses on passive bioclimatic strategies for energy efficiency and performance-driven design processes. the second semester addresses issues related to the environmental impact of materials, their durability and understanding of buildings’ life cycle. in that regard, students generally work with the transformation of an existing building. during the third semester, students are introduced to integrated energy design processes, relating environmental performance issues are to alternative energy systems, renewable energy systems’ integration, and zero emission buildings targets [5]. figure 4. structure of the msc program in sustainable architecture at ntnu the program accounts for a total of 120 ects and is divided, as all courses at ntnu, in modules of 7,5 ects. as for the whole faculty of architecture and design, design courses account for 15 credits while theory courses account for 7,5 each. in every semester, a combined theory and design course – where a different theory package is meant to provide a scientific basis for the development of integrated design processes accounts for a total of 22,5 credits. design and theory courses, accounting for 15 and 7,5 credits respectively, are evaluated separately and on the basis of independent assignments. remaining 7,5 credits per semester are used in the first semester for an introductory course on concepts and strategies for sustainable architecture, for multidisciplinary experts in team course (run by ntnu in collaboration with all faculties) 11 journal of sustainable architecture and civil engineering 2020/1/26 swot analysis addresses issues related to the environmental impact of materials, their durability and understanding of buildings’ life cycle. in that regard, students generally work with the transformation of an existing building. during the third semester, students are introduced to integrated energy design processes, relating environmental performance issues are to alternative energy systems, renewable energy systems’ integration, and zero emission buildings targets [5]. the program accounts for a total of 120 ects and is divided, as all courses at ntnu, in modules of 7,5 ects. as for the whole faculty of architecture and design, design courses account for 15 credits while theory courses account for 7,5 each. in every semester, a combined theory and design course – where a different theory package is meant to provide a scientific basis for the development of integrated design processes accounts for a total of 22,5 credits. design and theory courses, accounting for 15 and 7,5 credits respectively, are evaluated separately and on the basis of independent assignments. remaining 7,5 credits per semester are used in the first semester for an introductory course on concepts and strategies for sustainable architecture, for multidisciplinary experts in team course (run by ntnu in collaboration with all faculties) in the second and an elective course in the third one. within each course, high demands are made towards the development of integrated solutions taking into account concerns related to users and environmental context. interdisciplinary co-operation aims to let students explore the potential of integrated design methods and acquire valuable competences for their future praxis as building professionals. students develop a 30 ects master thesis in the fourth and last semester. theses are generally presented in the form of research reports, design projects or a combination of the two. besides students learn different kinds of digital tools during the program, no specific module about bim has been implemented until today in the program. however, a first small attempt was done last year within the laboratory of the first semester in which a session of tutorial on how to create a simple bim model in revit and export it in different simulations environments for conducting further energy analyses has been introduced. this session was ideated after having experienced of international students that in their background had the ability to model a building only in revit environment. furthermore in several occasions, it has been discussed about the possibility of inserting a bim module in the second semester, mostly for its potential for a fast accounting of materials and related emissions. this should facilitate design taking related to choice of materials and effort into minimizing the use of high-impact materials through optimization of number and dimensions of different elements (i.e. beams and columns as structure elements, dimension and number of openings, cladding elements etc.). a few students have developed their master thesis with the purpose of analysing the potential of bim in emissions accounting and its current use in norwegian companies. these works have been developed under the supervision of teachers responsible of the second semester. using and integrating the bim method in different study cycles in order to find out the possibilities of using and integrating the bim method in different study cycles, swot analysis was carried out in the following programs: bsc architectural technology and construction management (via university college), integrated studies architecture (ktu), msc sustainable architecture (ntnu) [6]. in all programmes was mentioned as a strength architecture connection with the civil engineering. bsc and integrated studies (ktu and via university college) contains both architectural and engineering disciplines and msc (ntnu) studies has a multidisciplinary nature: the program is open to both architects and engineers. that aspect gives the possibilities to introduce the bim complex in a holistic way. one more strength was settled down in all programs: students are trained to use the digital tools and to implement it in different kind of design processes. by comparing the strengths of the programmes, it has been noted that there are no tuition fee in danish and norwegian higher journal of sustainable architecture and civil engineering 2020/1/26 12 table 1 scot/swot analysis example internal external strengths what’s strong about your study programme, for example: bim use opportunities, education and professional training, student projects, software/equipment, qualification of staff in bim projects, financial support, staff training. challenges (weaknesses) what presents challenges, such as: financial support, short-staffed, space and time limitations, software/ equipment, staff training. note: strengths can also be weaknesses — a long-tenured staff may have a lot of experience, but they may be too set in their ways, or have stale ideas. opportunities opportunities are the thing your school/university has no control over, but could potentially take advantage of. for example: grants, partnerships, change in demographics, etc. try to think outside of the box on these. your ability to see opportunities coming could be significant. threats what external threats exist that could harm bim using/integration in study programme? some examples: the economic downturn, elimination of funding, university policy changes, etc. education institutions, while 70% lithuanian students and 100% international students in lithuania pay a tuition fee and it is the weakness of the programme. one more of the strengths of the studied programmes is the available or planned equipment, which students can use for their studies. this strength was mentioned in the analysis of bsc and integrated studies programs: via for 5 years has bim laboratory, while ktu expects to open the smart cities and infrastructure center into 2019. ntnu has a bim laboratory at the faculty of engineering in trondheim and a well-established research group in ntnu gjøvik. recently, the faculty of architecture and design at ntnu declared bim as an area for strategic development within the institute of architecture and planning. few of the most important strengths were mentioned of all three countries: close collaboration with researchers’ community, staff training in the field of bim. besides ktu mentioned students participation in international/national competitions, where students are implementing bim in their projects and ntnu mentioned possibility of developing a thesis based on bim knowledge and/or practice coupled with professional training in companies’ leaders in the bim sector. the fact that the bsc program contains both architectural and engineering disciplines gives possibilities. however, this strength has also a weakness imbedded. in the multidisciplinary content of the program, the engineering disciplines are described but the actual 3d engineering models (structural and hvac) are missing, that gives a less understanding and since the students are making individual projects, it is impossible for the engineering lecture staff to serve all students with individual models. all universities in their programs analysis noticed that there is a lack of bim competencies in lecturer staff and in ktu highlighted big business of teaching staff. despite many calls for developing individual competences among the teachers’ staff, there is still reluctance to develop the necessary skills. ktu also highlighted the lack of student motivation, which was not mentioned by the other two schools. most likely, this is related to paid studies in lithuania, which results in less students focusing on studies and more on job. in addition, student’s motivation to use bim is reducing after students returns from internship in the industry or in the architectural company, some of them experienced only a very limited use of bim implementation. this weakness was mentioned in two programs bsc and integrated studies. one more weakness of the programs was common for two hei (ktu and ntnu) the focus on integrated design processes represents a quality of the program but it is often challenging to ensure architectural quality in all the design projects. one special strength was setted down as also as challenge in ntnu diversity among students is generally reflected in different expectations, learning methods and experiences. this generally represent a richness of the program but can also be a challenge when defining teaching methodology and contents fulfilling different expectations, especially that there is a lack of a dedicated module, laboratory and/or course of bim in the msc program in sustainable architecture. 13 journal of sustainable architecture and civil engineering 2020/1/26 as one of the opportunities, in all programs swot analysis was mentioned the opportunity to establish cross-disciplinary cooperation among the different faculties or with different universities in the international level to run “a real bim-project” with all the respective disciplines involved with fully supplied discipline-models. one opportunity was settled dawn by ktu, also could be treated as a threat – from the 1st of july 2022 will become compulsory to use bim methods for the design and construction of all newly constructed complex and high value public sector buildings, but architects’ chamber of lithuania (a professional self-governing organization of certified architects) opposes mandatory introduction of bim, because that the lithuanian market is not ready for it and any forced application of technology is to be considered only as an attempt to restrict competition. architects’ chamber of lithuania is afraid of that the consequence of this design is probably the multiplication of typical buildings. therefore, in one hand this new law could be as an opportunity for adaptation bim into high education, because of strengthening the competences of digitalization of architecture students and increased involvement of students in international projects and opportunities for internships abroad, but in other hand as a threat, because architects’ chamber of lithuania is against it. via university college, see the opportunity of development of the educational bim-lab. in bim lab there should be opportunities to develop solid bim-projects where participation should be determinated by the educational discipline (arch – struc – hvac) and ntnu, see the opportunity of out of the lab into the city: organize visit on site for showing bim potentialities in construction management or visit in factories/great firms for bim design. understanding of architecture as use of standard commercially available components limiting freedom and creativeness in the design process was settled down not only in ktu swot analysis, but also in ntnu. via university college mentioned that greater savings in education could also affect the overall focus on bim implementation. in the coming 3 years the program suffer from an annual savings. changes in legislation and policy of the ktu and the ministry of education and science, influencing the instability of the study program in ktu. permanent change causes the demotivation of academic staff, and it will not be desirable to work with new methods. ntnu mentioned special threats, which are connected with their program: the largest concern is that of shifting too much the focus of the program from environmental impact analyses and sustainability concerns into construction and management. introducing bim might further increase complexity within the design process, resulting in lower attention towards sustainability concern. one more threat was mentioned by via university college – the lack of use of the ifc – format in the industry, which means small support from the industry and also from the government. a student survey was conducted to find out students’ opinions and knowledge about bim. the aim of this survey was to find out how they understand the bim term, which software’s they learned during the studies and etc. their experience will help to improve bim teaching methods in the architecture program. in the survey participated: 21 architecture program students from ktu (18 bsc level students (19 – 8 semester and 2 – 6 semester) and 3 msc students); 19 msc level sustainable architecture program students from ntnu and 80 bsc level architectural technology and construction management students from via (50 danish students and 30 international students). ntnu students are with different background: 86% have bsc diploma in architecture, 10 % building engineering and 4 % other. to the question „how do you understand what is bim (building information modelling)” 48 % of ktu students, 20 % via students and 28 % ntnu students answered that bim is digital processing and simulation of geometric and physical data in a construction process and subsequent operational phase; that bim is process, which covers the whole life-cycle of the building answered 14 % of student’s opinion survey about bim journal of sustainable architecture and civil engineering 2020/1/26 14 ntnu students, 29 % of via students and 10 % ktu students. 29 % via students and 28 % ntnu students answered that bim is digitization of construction and building operations, while just 10 % of ktu students picked this answer. biggest part of respondents understand bim meaning right. 8 0 10 20 30 40 50 60 70 80 up to 1 y. 1-2 y. more than 2 y. do not marked how many years have you been working at the architectural company? ktu ntnu via (50 danish students and 30 international students). ntnu students are with different background: 86% have bsc diploma in architecture, 10 % building engineering and 4 % other. to the question „how do you understand what is bim (building information modelling)” 48 % of ktu students, 20 % via students and 28 % ntnu students answered that bim is digital processing and simulation of geometric and physical data in a construction process and subsequent operational phase; that bim is process, which covers the whole life-cycle of the building answered 14 % of ntnu students, 29 % of via students and 10 % ktu students. 29 % via students and 28 % ntnu students answered that bim is digitization of construction and building operations, while just 10 % of ktu students picked this answer. biggest part of respondents understand bim meaning right. questions “do you work” and “how many years“ have you been working in the architectural company was given to find out do the students have work experience and after that they were asked to answer question "does the company where are you working use the bim method?" from the answers, we see that 71% ktu and ntnu students and only 14 % of via students have work experience in the architectural company. in the survey, one of the most important questions was “does the company where are you working use the bim method?” 60 % architectural companies, where ktu students are working, are using bim. ntnu survey results show that 53 % architectural companies, where ntnu students are working, are using bim. 2/3 of via respondents said that their company use bim. from the survey, we can do the conclusion that mostly architectural companies work with auto cad and/or revit. that shows that the architectural environment is to a certain degree prepared for the bim but they do not need this method because there are not a certain need from the customers also based on the legislation of research countries. it was interesting to find out which software’s ktu, via and ntnu students learned during the studies and compare their knowledge’s with what they need, therefore was given the question “what software’s did you learn to use during your studies?” to this question were asked to answer all respondents. results shows that 100 % of respondents from ktu learned to use autocad and just 29 % revit. these two software’s are taught in ktu architecture programme. comparing the via situation, we see opposite results 100 % of students learned revit, because it is the overall chosen software in the programme, and sketch up with 38 %, because it is taught in the international programme. ntnu survey shows, that 38% respondents learned revit, 19 % autocad during their studies. some of respondents wrote other software’s, which they learned during the study years: photoshop, coreldraw, rhinoceros, grasshopper and kangaroo physics. from the software’s, which students learned, we can do the conclusion that majority of programs are used for visualizations and design creation. majority of respondents think that it is important for the architect to be able work in the bim method: ktu 57 % (very important) and 19 % (important); via – 38 % (very important) and 46 % (important); ntnu 29 % (very important) and 48 % (important). majority of respondents are very much interested: 0 20 40 60 80 100 revit autocad archicad sketchup 3d max solibri what software did you learn to use during your studies? ktu ntnu via questions “do you work” and “how many years“ have you been working in the architectural company was given to find out do the students have work experience and after that they were asked to answer question “does the company where are you working use the bim method?” from the answers, we see that 71% ktu and ntnu students and only 14 % of via students have work experience in the architectural company. in the survey, one of the most important questions was “does the company where are you working use the bim method?” 60 % architectural companies, where ktu students are working, are using bim. ntnu survey results show that 53 % architectural companies, where ntnu students are working, are using bim. 2/3 of via respondents said that their company use bim. from the survey, we can do the conclusion that mostly architectural companies work with auto cad and/or revit. that shows that the architectural environment is to a certain degree prepared for the bim but they do not need this method because there are not a certain need from the customers also based on the legislation of research countries. it was interesting to find out which software’s ktu, via and ntnu students learned during the studies and compare their knowledge’s with what they need, therefore was given the question “what software’s did you learn to use during your studies?” to this question were asked to answer all respondents. results shows that 100 % of respondents from ktu learned to use autocad and just 29 % revit. these two software’s are taught in ktu architecture programme. comparing the via situation, we see opposite results 100 % of students learned revit, because it is the overall chosen software in the programme, and sketch up with 38 %, because it is taught in the international programme. ntnu survey shows, that 38% respondents learned revit, 19 % autocad during their studies. some of respondents wrote other software’s, which they learned during the study years: photoshop, coreldraw, rhinoceros, grasshopper and kangaroo physics. from the software’s, which 8 0 10 20 30 40 50 60 70 80 up to 1 y. 1-2 y. more than 2 y. do not marked how many years have you been working at the architectural company? ktu ntnu via (50 danish students and 30 international students). ntnu students are with different background: 86% have bsc diploma in architecture, 10 % building engineering and 4 % other. to the question „how do you understand what is bim (building information modelling)” 48 % of ktu students, 20 % via students and 28 % ntnu students answered that bim is digital processing and simulation of geometric and physical data in a construction process and subsequent operational phase; that bim is process, which covers the whole life-cycle of the building answered 14 % of ntnu students, 29 % of via students and 10 % ktu students. 29 % via students and 28 % ntnu students answered that bim is digitization of construction and building operations, while just 10 % of ktu students picked this answer. biggest part of respondents understand bim meaning right. questions “do you work” and “how many years“ have you been working in the architectural company was given to find out do the students have work experience and after that they were asked to answer question "does the company where are you working use the bim method?" from the answers, we see that 71% ktu and ntnu students and only 14 % of via students have work experience in the architectural company. in the survey, one of the most important questions was “does the company where are you working use the bim method?” 60 % architectural companies, where ktu students are working, are using bim. ntnu survey results show that 53 % architectural companies, where ntnu students are working, are using bim. 2/3 of via respondents said that their company use bim. from the survey, we can do the conclusion that mostly architectural companies work with auto cad and/or revit. that shows that the architectural environment is to a certain degree prepared for the bim but they do not need this method because there are not a certain need from the customers also based on the legislation of research countries. it was interesting to find out which software’s ktu, via and ntnu students learned during the studies and compare their knowledge’s with what they need, therefore was given the question “what software’s did you learn to use during your studies?” to this question were asked to answer all respondents. results shows that 100 % of respondents from ktu learned to use autocad and just 29 % revit. these two software’s are taught in ktu architecture programme. comparing the via situation, we see opposite results 100 % of students learned revit, because it is the overall chosen software in the programme, and sketch up with 38 %, because it is taught in the international programme. ntnu survey shows, that 38% respondents learned revit, 19 % autocad during their studies. some of respondents wrote other software’s, which they learned during the study years: photoshop, coreldraw, rhinoceros, grasshopper and kangaroo physics. from the software’s, which students learned, we can do the conclusion that majority of programs are used for visualizations and design creation. majority of respondents think that it is important for the architect to be able work in the bim method: ktu 57 % (very important) and 19 % (important); via – 38 % (very important) and 46 % (important); ntnu 29 % (very important) and 48 % (important). majority of respondents are very much interested: 0 20 40 60 80 100 revit autocad archicad sketchup 3d max solibri what software did you learn to use during your studies? ktu ntnu via 15 journal of sustainable architecture and civil engineering 2020/1/26 students learned, we can do the conclusion that majority of programs are used for visualizations and design creation. majority of respondents think that it is important for the architect to be able work in the bim method: ktu 57 % (very important) and 19 % (important); via – 38 % (very important) and 46 % (important); ntnu 29 % (very important) and 48 % (important). majority of respondents are very much interested: ktu 48 %, via – 28 %, ntnu – 15 % or interested: ktu 28 %, via – 40 %, ntnu – 54 %, into bim modelling. in this survey, respondents were asked to answer to few open questions. to the question, “which characteristics and potentialities of bim are you mostly interested in?” respondents mentioned: 3d models creation; connecting the same model with different parts of the project; cooperation between different specialists; an opportunity to edit the project and see the changes very fast in all parts of the project; the concept of open data and interaction between different software; quick estimate preparation; data sheets; project management. to the question, “what skills should you gain during architectural studies that enables you to work on the bim method?” respondents mentioned 3d models, quick estimate preparation; data sheets; ability to work with different software; revit, making schedules majority respondents answered to the final open question, “in which semester should be integrated course how to use bim method?”, that integration of bim should start from the first semester and to be used in all studies. fig. 5 structure of integration of the international bim project in different study cycles in via college, denmark, the progression of bim uses through the constructing architect courses´ semesters happens via 5 focus areas: 1. basic modelling and extraction from drawings; 2. quantity take-offs; 3. utilization of the properties data, incl. establishment of own properties data; 4. visualization; 5. integration with other software applications (hereafter called programs). in ktu architectural study programme progression of bim uses going by 3 main focus areas: 1. integration to elective subjects; 2. the development of design based subjects; 3. cooperation with praxis subjects (join project). model for integration of the international bim project in different study cycles 9 ktu 48 %, via – 28 %, ntnu – 15 % or interested: ktu 28 %, via – 40 %, ntnu – 54 %, into bim modelling. in this survey, respondents were asked to answer to few open questions. to the question, “which characteristics and potentialities of bim are you mostly interested in?” respondents mentioned: 3d models creation; connecting the same model with different parts of the project; cooperation between different specialists; an opportunity to edit the project and see the changes very fast in all parts of the project; the concept of open data and interaction between different software; quick estimate preparation; data sheets; project management. to the question, “what skills should you gain during architectural studies that enables you to work on the bim method?” respondents mentioned 3d models, quick estimate preparation; data sheets; ability to work with different software; revit, making schedules majority respondents answered to the final open question, “in which semester should be integrated course how to use bim method?”, that integration of bim should start from the first semester and to be used in all studies. model for integration of the international bim project in different study cycles. in via college, denmark, the progression of bim uses through the constructing architect courses´ semesters happens via 5 focus areas: 1. basic modelling and extraction from drawings; 2. quantity take-offs; 3. utilization of the properties data, incl. establishment of own properties data; 4. visualization; 5. integration with other software applications (hereafter called programs). in ktu architectural study programme progression of bim uses going by 3 main focus areas: 1. integration to elective subjects; 2. the development of design based subjects; 3. cooperation with praxis subjects (join project). in ntnu sustainable architecture study programme a first attempt was done in the laboratory of the first semester in which a session of tutorial on how to create a simple bim model in revit and export it in different simulations environments for conducting further energy analyses has been introduced. figure 5. structure of integration of the international bim project in different study cycles conclusions  in swot analysis was find out that in bsc architectural technology and construction management (via university college), integrated studies architecture (ktu), msc sustainable architecture (ntnu) programmes was mentioned as the strengths: architecture connection with the civil engineering; in via and ntnu there are no tuition fee, while 70% lithuanian students and 100% international students in lithuania pay a tuition fee and it is the weakness of the lithuanian programme; close collaboration with researchers’ community, staff training in the field of bim.  all universities in their programs swot analysis noticed that there is a lack of bim competencies in lecturer staff and in ktu highlighted big business of teaching staff and the lack of student motivation, which was not mentioned by the other two schools.  as one of the opportunities, in all programs swot analysis was mentioned the opportunity to in t e r n a t io n a l b im p r o je c t kaunas university of technology practice based subject 3 ects elective subject 6 ects design based subject 12 ects via university college norvegian science and technoogy university design based subject 20 ects eleective subject 10 ects design based subject 15 ects 5th semester 6th semester 5th semester 4th semester 5th semester 1st semester journal of sustainable architecture and civil engineering 2020/1/26 16 in ntnu sustainable architecture study programme a first attempt was done in the laboratory of the first semester in which a session of tutorial on how to create a simple bim model in revit and export it in different simulations environments for conducting further energy analyses has been introduced. conclusions “nordplus” projekto pagalba statybos ir architektūros fakultete tobulinamos studijų programos: https://saf.ktu.edu/news/nordplus-projekto-pagalba-statybos-ir-architekturos-fakultete-tobulinamos-studiju-programos/, 2017-09-07. project execution planning guide-v2.0: bim project execution planning guide, 2018-06-20. ia university college, architectural technology & construction management study programme: https:// en.via.dk/programmes/technology-and-construction/architectural-technology-bachelor , 2018-06-20. kaunas university of technology, architecture study programme: https://admissions.ktu.edu/?study-program=v-architecture, 2018-06-20. norvegian science and technoogy university, sustainable architecture study programme: https:// www.ntnu.edu/studies/mssusarc, 2018-06-20. the researchers of the ktu saf, together with colleagues from the nordic countries, examined bim prospects in studies: https://fcea.ktu.edu/news/ the-researchers-of-the-ktu-saf-together-withcolleagues-from-the-nordic-countries-examinedbim-prospects-in-studies/, 2018-10-22. references _ in swot analysis was find out that in bsc architectural technology and construction management (via university college), integrated studies architecture (ktu), msc sustainable architecture (ntnu) programmes was mentioned as the strengths: architecture connection with the civil engineering; in via and ntnu there are no tuition fee, while 70% lithuanian students and 100% international students in lithuania pay a tuition fee and it is the weakness of the lithuanian programme; close collaboration with researchers’ community, staff training in the field of bim. _ all universities in their programs swot analysis noticed that there is a lack of bim competencies in lecturer staff and in ktu highlighted big business of teaching staff and the lack of student motivation, which was not mentioned by the other two schools. _ as one of the opportunities, in all programs swot analysis was mentioned the opportunity to establish cross-disciplinary cooperation among the different faculties or with different universities in the international level to run “a real bim-project” with all the respective disciplines involved with fully supplied discipline-models. _ understanding of architecture as use of standard commercially available components limiting freedom and creativeness in the design process was settled down in ktu and ntnu swot analysis. as special weakness was mention just in ktu swot analysis: permanent changes in legislation and policy of the ktu and the ministry of education and science causes the demotivation of academic staff, and it will not be desirable to work with new methods. _ in the students survey participated 120 students (21 ktu, 19 ntnu, 80 via). in the survey was find out that biggest part of students from all countries understand bim meaning; the possibilities which this method is giving, but face with the problem, that bim is not very popular between architectural companies as architectural environment is just to a certain degree prepared for the bim and they do not need this method because there are not a certain need from the customers also based on the legislation of all countries. 17 journal of sustainable architecture and civil engineering 2020/1/26 aušra mlinkauskienė associate professor kaunas university of technology, faculty of civil engineering and architecture main research area cultural heritage, protected areas, cultural landscapes, urban structures. address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 300450 e-mail: ausra.mlinkauskiene@ktu.lt. about the authors laura jankauskaitėjurevičienė lecturer kaunas university of technology, faculty of civil engineering and architecture main research area cultural heritage, architectural design, hbim, parametric architecture. address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 300450 e-mail: laura.jankauskaitejureviciene@ktu.lt per christensen lecturer – bim coordinator master of ict and learning via architectural technology and construction management main research area bim processes and legislation cscl computer supported collaborative learning. address chr. m. østergaards vej 4, dk 8700 horsens tel. +45 87 55 40 00 e-mail: pc@via.dk luca finocchiaro associate professor norwegian university of science and technology, department of architecture and technology main research area architectural design, climate changes, zero emission buildings, sustainable architecture. address alfred getz vei 3 _ no 7491 trondheim e-mail: luca.finocchiaro@ntnu.no gabriele lobaccaro researcher norwegian university of science and technology, department of architecture and technology main research area environmental engineering, climate models, urban planning, sustainable architecture, building physics. address alfred getz vei 3 _ no 7491 trondheim e-mail: gabriele.lobaccaro@ntnu.no mailto:ausra.mlinkauskiene@ktu.lt mailto:laura.jankauskaite-jureviciene@ktu.lt mailto:laura.jankauskaite-jureviciene@ktu.lt mailto:pc@via.dk mailto:luca.finocchiaro@ntnu.no mailto:gabriele.lobaccaro@ntnu.no journal of sustainable architecture and civil engineering 2019/1/24 44 *corresponding author: stig.geving@ntnu.no the effect of repeated moisture cycles on the air tightness of traditional clamped vapour barrier joints received 2018/12/11 accepted after revision 2019/02/05 journal of sustainable architecture and civil engineering vol. 1 / no. 24 / 2019 pp. 44-51 doi 10.5755/j01.sace.24.1.22159 the effect of repeated moisture cycles on the air tightness of traditional clamped vapour barrier joints jsace 1/24 http://dx.doi.org/10.5755/j01.sace.24.1.22159 stig geving*, øyvind norvik norwegian university of science and technology, dept. of building and environmental technology, høgskoleringen 7a, no-7491 trondheim, norway lars gullbrekken sintef building and infrastructure, no-7491 trondheim, norway introduction in this study it has been investigated whether and to what extent, repeated moisture cycles affect the air leakage through clamped overlap joints in the vapour barrier layer. use of clamped joints is a traditional way to make airtight joints in the windand vapour barrier used in wood frame walls in norway and other countries. a laboratory test has been carried out, with a total of 63 pressure tests, being carried out on 9 test samples, consisting of overlap joints of 0.15 mm polyethylene film clamped between a wooden batten and stud. each sample was tested seven times after repeated drying and humidification, where the moisture values of the sub-cycles were chosen to represent the annual variations of indoor relative humidity. the laboratory test materials were mounted with machine nails with various center spacing (150 mm, 300 mm and 450 mm). the overlap joints of the vapour barrier were in the end of the test sealed with adhesive tape, revealing to what extent this over a longer period of time will be beneficial. the results showed that the first moisture cycle (drying) resulted in significant increase of air leakage for all the sample variants. throughout the moisture cycles, a further strong leakage development for center spacing 450 mm was observed, which was less for 300 mm, and non-existent for 150 mm. the gain of using structural adhesive tape was found to largely depend on the level of perforation resulting from the nails and their center distance. adhesive tape on the joints resulted in the greatest reduction in leakage numbers where the center distance between the nails was high, i.e. the reduction was 58% for center distance 450 mm. however, with shorter center distance the use of tape only decreased the air leakage between 22-39%, revealing the fact that a large part of the joint leakage is through the nail perforations. keywords: vapour barrier, air tightness, clamped joint, building envelope. air leakages through building envelopes lead to higher energy consumption, may result in moisture accumulation problems in the building envelope, and it may also affect the indoor air quality (airaksinen et al. 2003, janssens and hens 2003, relander et al. 2012, tuominen et al. 2014, kalamees et al. 2017). the requirements regarding reduced energy demand in buildings are continuously tightened and by 2020 all new buildings in norway are required to be almost zero energy buildings (epbd 2016, tek17 2017). therefore, the requirements for airtightness in the norwegian building regulations were strengthened in 2017, from 2.5 air changes per hour at 50 pa (volume normalized) for residential buildings and 1.5 for other buildings, to 0.6 for all buildings (tek17 2017). 45 journal of sustainable architecture and civil engineering 2019/1/24 the airtightness of the building envelope is achieved through the durability and connectivity of the air barrier to other building components (kalamees et al. 2017). typical building envelope constructions, both in norway and other countries, use clamped joints as a traditional way to attain airtight joints in the windand vapour barrier layer. the airtightness of clamped joints depends on several parameters including geometry of the wooden batten, type of fixing and center to center distance of the fixings. some of these parameters have already been investigated in several laboratory studies summarized and discussed in (gullbrekken et al., 2012a; gullbrekken et al., 2012b). they found that nails account for higher air leakage rates than screws. wetting and drying cycles (imitating the yearly relative humidity variations) resulted in higher air leakages due to shrinking and swelling of the wooden battens. in addition, the center to center distance of 600 mm between fixings generally resulted in higher air leakage rates compared to shorter center to center distances such as 300 mm and 150 mm. however, the effect of several years of cyclic shrinking and swelling of wood materials used in clamped joints and their influence on the airtightness of the building envelope, have not yet been investigated. the aim of this study is to investigate how the airtightness of clamped vapour barrier joints are affected by several drying and wetting cycles caused by moisture variations in indoor environment. the durability of the joint is presumably unaffected by material degradation, but the function is affected by the shrinking and swelling of the wooden materials. methodsgeneral the general concept of the laboratory test was to expose clamped vapour barrier joints to several repeated cycles of drying and wetting. this was done to simulate the yearly shrinking and swelling of the wood close to the joint, which again is expected to influence negatively on the air tightness of the joint. a short description of the chosen procedure is given in the following: 1. different test samples of clamped vapour barrier joints were made. 2. the test samples were wetted to a “high” wooden moisture content (typical summer condition). 3. the test samples were mounted on a test box and air leakage of the samples were measured. 4. the test samples were dried to a “low” wooden moisture content (typical winter condition). 5. the test samples were again mounted on a test box and air leakage of the samples were measured. 6. pt 2-5 were repeated three times, simulating 2,5 years starting with summer condition and ending in a winter condition. this gave six air leakage tests for each test sample. 7. to see the effect of taping of joints, the joints were taped and a final air leakage test were made. to assess the practical implications of the measured air leakages, the resulting air change rate at 50 pa was estimated for two different case buildings, see chapter “numerical estimation for case buildings”. material and test samples a typical clamped vapour barrier joint in wood frame walls are made by nailing or screwing a wooden batten to the wooden stud with the overlap vapour barrier joint in between. the battens were chosen with dimension 36 x 48 mm (width x thickness). in norwegian building tradition it is normally recommended to use batten thickness between 11-36 mm to clamp the overlap vapour and wind barrier joints. for thicker battens the potential to get a gap between the batten and stud due to the yearly shrinking of the batten is higher, and thereby giving a reduced pressure on the overlap joint. the reason for chosing a batten with thickness of 48 mm is that it has become usual in norway recent years to mount 50 mm mineral wool (and using 48 mm battens) on the internal side of the vapour barrier. this makes it possible to mount for instance electric cables in this layer without perforating the vapour barrier. to fix the battens machine nails with dimension 3,2 x 90 mm were used. three different center to center (“cc”) distances of the nails were used; 150, 300 and 450 mm. the battens were nailed to a stud with dimension 36 x 98 mm. the reduced stud journal of sustainable architecture and civil engineering 2019/1/24 46 dimension (normal thickness is 148 mm or thicker) is assumed not to have any effect on the differential movements between stud, batten and nail. both battens and studs consisted of norway spruce class c24. each test sample consisted of two joints each 900 mm long, see fig. 1, i.e. total length 1,8 m per sample. three samples for each center to center fig. 1 assembly of the test samples. two 1000 mm studs are placed in a mounting rack. then the pe-foil is mounted before the 1000 mm long batten is nailed to the stud. the joint ends was taped to avoid unintentional air leakage, so the joint length was a little bit shorter than the stud/batten (900 mm) to mount for instance electric cables in this layer without perforating the vapour barrier. to fix the battens machine nails with dimension 3,2 x 90 mm were used. three different center to center (“cc”) distances of the nails were used; 150, 300 and 450 mm. the battens were nailed to a stud with dimension 36 x 98 mm. the reduced stud dimension (normal thickness is 148 mm or thicker) is assumed not to have any effect on the differential movements between stud, batten and nail. both battens and studs consisted of norway spruce class c24. each test sample consisted of two joints each 900 mm long, see fig. 1, i.e. total length 1,8 m per sample. three samples for each center to center distance (150, 300 and 450 mm) were produced, i.e. a total of 9 samples were made. the nail gun pressure was set to give a surface immersion for the nail head of approximately 1-2 mm. fig. 1. assembly of the test samples. two 1000 mm studs are placed in a mounting rack. then the pefoil is mounted before the 1000 mm long batten is nailed to the stud. the joint ends was taped to avoid unintentional air leakage, so the joint length was a little bit shorter than the stud/batten (900 mm). 2.3. wetting and drying procedure the intention of the drying and wetting procedure described in chapter 2.2 was to simulate the yearly moisture cycles that the wood close to the vapour barrier joint (wooden batten and inner half of wooden stud) experiences. simulations of the hygrothermal conditions in a south facing wood frame wall were conducted with wufi-2d (künzel 1995). the wood frame wall had the following layers from inside; 13 mm gypsum board, 48 mm mineral wool/48 x 48 mm wooden batten, 0,15 mm polyethylene foil, 198 mm mineral wool/198 x 48 mm wooden stud, 13 mm gypsum board, 25 mm ventilated air layer and 18 mm wooden cladding. as external climate the moisture design reference year (mdry) for gardermoen was chosen, a weather station close to oslo in the south of norway. as internal climate a moisture excess of 4 g/m3 in the heating season (outdoor temperature below + 5 °c) was chosen based on findings of geving and holme (2012), with linear transition to 1,5 g/m3 at external temperatures above 15 °c. after the first period of stabilization, the simulations showed that the moisture content will oscillate between 7.8 and 12.7 weight% for the inner half of the wood stud and between 9 and 14,2 weight% for the wooden batten. on the basis of these results, the target values for the experimental setup were chosen to 7 weight% (winter condition) and 14 weight% (summer condition). distance (150, 300 and 450 mm) were produced, i.e. a total of 9 samples were made. the nail gun pressure was set to give a surface immersion for the nail head of approximately 1-2 mm. wetting and drying procedure the intention of the drying and wetting procedure described in chapter “material and test samples” was to simulate the yearly moisture cycles that the wood close to the vapour barrier joint (wooden batten and inner half of wooden stud) experiences. simulations of the hygrothermal conditions in a south facing wood frame wall were conducted with wufi-2d (künzel 1995). the wood frame wall had the following layers from inside; 13 mm gypsum board, 48 mm mineral wool/48 x 48 mm wooden batten, 0,15 mm polyethylene foil, 198 mm mineral wool/198 x 48 mm wooden stud, 13 mm gypsum board, 25 mm ventilated air layer and 18 mm wooden cladding. as external climate the moisture design reference year (mdry) for gardermoen was chosen, a weather station close to oslo in the south of norway. as internal climate a moisture excess of 4 g/m3 in the heating season (outdoor temperature below + 5 °c) was chosen based on findings of geving and holme (2012), with linear transition to 1,5 g/m3 at external temperatures above 15 °c. after the first period of stabilization, the simulations showed that the moisture content will oscillate between 7.8 and 12.7 weight% for the inner half of the wood stud and between 9 and 14,2 weight% for the wooden batten. on the basis of these results, the target values for the experimental setup were chosen to 7 weight% (winter condition) and 14 weight% (summer condition). drying and wetting were performed in an oven at 70 °c to speed up the process. the wetting was performed by installing the samples and a specific amount of water in a sealed air and water vapour tight box positioned inside the oven, see fig. 2. the temperature stratification inside the box was controlled fig. 2 set up of test box for the wetting procedure. the box was then placed in the oven drying and wetting were performed in an oven at 70 °c to speed up the process. the wetting was performed by installing the samples and a specific amount of water in a sealed air and water vapour tight box positioned inside the oven, see fig. 2. the temperature stratification inside the box was controlled by thermocouples. during the drying and wetting, the wood moisture content was controlled by measuring the electrical resistance between two electrodes positioned in two of the wood samples. in addition all the samples were weighed before the different airtightness measurements. each wetting and drying cycle lasted in average 145 and 115 hours respectively. finally, the dry weight of the samples were measured by dryng in the oven at 110 °c. by extracting the weight of the polyethylene foil, tape and nails the average moisture content of the wood could be calculated for every part of the test cycle. fig. 2. set up of test box for the wetting procedure. the box was then placed in the oven. 2.4. air leakage testing the resistance to penetration of air through pinched joints in the vapour barrier was tested in accordance with en 12114 (en12114 2000). the air leakage was measured at a pressure difference of 20, 30, 50, 70 and 90 pa. by linear interpolation of the measurement values the air leakage at 50 pa pressure difference was calculated. the airtight box used for the moistening of the samples was also used for the air leakage measurements. the pe-foil of the samples was positioned between a sealing gasket on the airtight box and a sealing gasket on a wooden frame fixed with bolts with a specific momentum, see fig. 3. the airtightness of the airtight box including the gaskets was accounted for by measuring the air leakage at 50 pa pressure difference with an airtight polyethylene foil (no joints) as a sample. this was done after each of the different test sequences. the leakage values ranged from 0,17 to 3,65 litre/h at 50 pa, which was subtracted from the previous ordinary air leakage test. at the end of the test (after the last drying) the overlap joint was taped without demounting the sample or the wooden batten. the top overlap of the polyethylene foil was portruding approx. 2 cm to the side of the batten, allowing the joint to be sealed with a special polyethylene tape (45 mm wide). 47 journal of sustainable architecture and civil engineering 2019/1/24 by thermocouples. during the drying and wetting, the wood moisture content was controlled by measuring the electrical resistance between two electrodes positioned in two of the wood samples. in addition all the samples were weighed before the different airtightness measurements. each wetting and drying cycle lasted in average 145 and 115 hours respectively. finally, the dry weight of the samples were measured by dryng in the oven at 110 °c. by extracting the weight of the polyethylene foil, tape and nails the average moisture content of the wood could be calculated for every part of the test cycle. air leakage testing the resistance to penetration of air through pinched joints in the vapour barrier was tested in accordance with en 12114 (en12114 2000). the air leakage was measured at a pressure difference of 20, 30, 50, 70 and 90 pa. by linear interpolation of the measurement values the air leakage at 50 pa pressure difference was calculated. the airtight box used for the moistening of the samples was also used for the air leakage measurements. the pe-foil of the samples was positioned between a sealing gasket on the airtight box and a sealing gasket on a wooden frame fixed with bolts with a specific momentum, see fig. 3. the airtightness of the airtight box including the gaskets was accounted for by measuring the air leakage at 50 pa pressure difference with an airtight polyethylene foil (no joints) as a sample. this was done after each of the different test sequences. the leakage values ranged from 0,17 to 3,65 litre/h at 50 pa, which was subtracted from the previous ordinary air leakage test. fig. 3 assembly of the sample to the airtight box for air lekage testing. to the right is shown the final testing with taped joints fig. 3. assembly of the sample to the airtight box for air lekage testing. to the right is shown the final testing with taped joints. 2.5. numerical estimation for case buildings in order to evaluate the practical implications of the measured air leakages two case buildings has been investigated; a single family house and an office building with heated area/volume of respectively 140 m2/336 m3 and 12870 m2/46191 m3. the resulting air change rate for the two case buildings has been estimated by use of the results from the air leakage measurements. the estimated air change rate only included leakages through the joints in the vapour barrier. this means that the air leakage resistance from other material layers such as interior cladding and wind barrier are not accounted for. in order to calculate joint lengths in the two case houses some assumptions and simplifications have been made: all the air leakages in the buildings is through the clamped joints in the vapour barrier (no leakages through the roof). pe-foil with a length of 15 m and a width of 2,6 m. clamped joints at bottom and head sills, corners and around the windows this gave a total clamped joint length for the single family house and the office building of respectively 320 m and 5052 m. 3. results and discussion 3.1.experimental study the real moisture content of the wooden part of the test samples are shown in fig. 4. as the figure shows the high level (summer condition) varies between 11,9 to 14,7 weight%, with an average of 13,3 weight%. the low level (winter condition) varies between 5,7 to 6,5 weight%, with an average of 6,0 weight%. this is considered reasonable close to the target values for the experimental setup (14 and 7 weight%). threaded bolt gasket rack airtight box sample gasket frame nut frame at the end of the test (after the last drying) the overlap joint was taped without demounting the sample or the wooden batten. the top overlap of the polyethylene foil was portruding approx. 2 cm to the side of the batten, allowing the joint to be sealed with a special polyethylene tape (45 mm wide). numerical estimation for case buildings in order to evaluate the practical implications of the measured air leakages two case buildings has been investigated; a single family house and an office building with heated area/volume of respectively 140 m2/336 m3 and 12870 m2/46191 m3. the resulting air change rate for the two case buildings has been estimated by use of the results from the air leakage measurements. the estimated air change rate only included leakages through the joints in the vapour barrier. this means that the air leakage resistance from other material layers such as interior cladding and wind barrier are not accounted for. in order to calculate joint lengths in the two case houses some assumptions and simplifications have been made: _ all the air leakages in the buildings is through the clamped joints in the vapour barrier (no leakages through the roof). journal of sustainable architecture and civil engineering 2019/1/24 48 _ pe-foil with a length of 15 m and a width of 2,6 m. _ clamped joints at bottom and head sills, corners and around the windows this gave a total clamped joint length for the single family house and the office building of respectively 320 m and 5052 m. experimental study the real moisture content of the wooden part of the test samples are shown in fig. 4. as the figure shows the high level (summer condition) varies between 11,9 to 14,7 weight%, with an average of 13,3 weight%. the low level (winter condition) varies between 5,7 to 6,5 weight%, with an average of 6,0 weight%. this is considered reasonable close to the target values for the experimental setup (14 and 7 weight%). results and discussion fig. 4 moisture content (including standard deviation) of wooden samples during the test cycle measured by drying and weighing fig. 4. moisture content (including standard deviation) of wooden samples during the test cycle measured by drying and weighing. the measured air leakage through the different vapour barrier joints are shown in fig. 5. all the measurements show that initially before any drying the joints are very airtight, between 0,9 to 4,5 litre/hm, with cc 450 mm nail distance giving the higher value. after the first cycle of drying the air leakage is increasing to between 32 to 40 litre/hm. this is caused by the shrinking of the wooden batten and stud when going from a moisture content of approximately 14 weight% to 6 weight%. the shrinkage is causing an increased air gap between the batten and stud where air leakage can occur, see fig. 6. after the first wetting cycle up to approximately 13 weight% the air leakage is reduced again, however to a somewhat higher level than the initial air leakage. for the remaining drying and wetting cycles we observe that for the samples with cc 450 mm the air leakage is increasing dramatically for each cycle, especially after each period of drying. the air leakage after the second drying cycle has increased 97% compared to the air leakage after the first drying cycle. between the second and third drying cycle the increase in air leakage is 45 %. for cc 150 mm and cc 300 mm we do however not see the same effect, i.e. the air leakage is approximately the same after each drying period. this indicate that a center to center distance between the nails of up to approximately 300 mm may be acceptable, but the clamping effect may not be durable for repeated yearly moisture cycles for center to center distances above 300 mm. it should however be noted that the current study only included 2,5 yearly cycles, while we would expect the life cycle of the building to give at least 50 yearly cycles. this could lead to increased air leakage also for cc 150 mm and cc 300 mm. we do for instance observe a small increase in air leakage between the first and second drying cycle (20% increase) for cc 300 mm. the effect of shrinkage and swelling on the air leakage is obviously also dependant on the thickness of the wooden batten, which is thicker than the recommended maximum thickness for battens used for clamping vapour barrier joints (approximately 36 mm according to norwegian tradition). a thick batten will in total have a larger shrinkage/swelling compared to a thinner batten, meaning that the potential for creating an air gap like shown in fig. 6 is larger. other parameters that may affect the shrinkage (given the variation in yearly moisture content is the same) is the length of the nail and the design of the nail (surface texture etc). the effect of taping the overlap joint is relatively strong, reducing the air leakage with 58%, 39% and 22% for the cc 450 mm, cc 300 mm and cc 150 mm respectively. one could have expected that the taping should have reduced the air leakage close to the initial level before the first drying cycle, however this is far from happening. one possible explanation is that a large part of the air leakage during dry conditions is through the fixing holes of the nails through the vapour barrier. this is anyway an interesting finding even for cases when all the joints are taped, since there will always be a number 0 2 4 6 8 10 12 14 16 initial dry 1 moist 1 dry 2 moist 2 dry 3 m oi st ru e co nt en t ( w ei gh t% ) cc 450 mm cc 300 mm cc 150 mm the measured air leakage through the different vapour barrier joints are shown in fig. 5. all the measurements show that initially before any drying the joints are very airtight, between 0,9 to 4,5 litre/hm, with cc 450 mm nail distance giving the higher value. after the first cycle of drying the air leakage is increasing to between 32 to 40 litre/hm. this is caused by the shrinking of the wooden batten and stud when going from a moisture content of approximately 14 weight% to 6 weight%. the shrinkage is causing an increased air gap between the batten and stud where air leakage can occur, see fig. 6. after the first wetting cycle up to approximately 13 weight% the air leakage is reduced again, however to a somewhat higher level than the initial air leakage. for the remaining drying and wetting cycles we observe that for the samples with cc 450 mm the air leakage is increasing dramatically for each cycle, especially after each period of drying. the air leakage after the second drying cycle has increased 97% compared to the air leakage after the first drying cycle. between the second and third drying cycle the increase in air leakage is 45 %. for cc 150 mm and cc 300 mm we do however not see the same effect, i.e. the air leakage is approximately the same after each drying period. this indicate that a center to center distance between the nails of up to approximately 300 mm may be acceptable, but the clamping effect may not be durable for repeated yearly moisture cycles for center to center distances above 300 mm. it should however be noted that the current study only included 2,5 yearly cycles, while we would expect the life cycle of the building to give at least 50 yearly cycles. this could lead to increased air leakage also for cc 150 mm and cc 300 mm. we do for instance observe a small increase in air leakage between the first and second drying cycle (20% increase) for cc 300 mm. the effect of shrinkage and swelling on the air leakage is obviously also dependant on the thickness of the wooden batten, which is thicker than the recommended maximum thickness for battens used for clamping vapour barrier joints (approximately 36 mm according to norwegian tradition). a thick batten will in total have a larger shrinkage/swelling compared to a thinner batten, 49 journal of sustainable architecture and civil engineering 2019/1/24 fig. 5 average air leakage (including standard deviation) through the different samples during the drying and wetting cycles. the results are given per meter joint for the three different center to center distances of the nails; 150, 300 and 450 mm fig. 6 shrinkage of the wooden batten and stud reduces the clamping effect by creating an air gap where air might leak of holes through the vapour barrier from the nails or screws. the configuration of fixing method when using wooden battens at the interior side of the vapour barrier may therefore be of interest even when taping of joints are used. fig. 5. average air leakage (including standard deviation) through the different samples during the drying and wetting cycles. the results are given per meter joint for the three different center to center distances of the nails; 150, 300 and 450 mm. fig. 6. shrinkage of the wooden batten and stud reduces the clamping effect by creating an air gap where air might leak. 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 450 mm 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 300 mm 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 150 mm of holes through the vapour barrier from the nails or screws. the configuration of fixing method when using wooden battens at the interior side of the vapour barrier may therefore be of interest even when taping of joints are used. fig. 5. average air leakage (including standard deviation) through the different samples during the drying and wetting cycles. the results are given per meter joint for the three different center to center distances of the nails; 150, 300 and 450 mm. fig. 6. shrinkage of the wooden batten and stud reduces the clamping effect by creating an air gap where air might leak. 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 450 mm 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 300 mm 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 150 mm of holes through the vapour barrier from the nails or screws. the configuration of fixing method when using wooden battens at the interior side of the vapour barrier may therefore be of interest even when taping of joints are used. fig. 5. average air leakage (including standard deviation) through the different samples during the drying and wetting cycles. the results are given per meter joint for the three different center to center distances of the nails; 150, 300 and 450 mm. fig. 6. shrinkage of the wooden batten and stud reduces the clamping effect by creating an air gap where air might leak. 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 450 mm 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 300 mm 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 150 mm of holes through the vapour barrier from the nails or screws. the configuration of fixing method when using wooden battens at the interior side of the vapour barrier may therefore be of interest even when taping of joints are used. fig. 5. average air leakage (including standard deviation) through the different samples during the drying and wetting cycles. the results are given per meter joint for the three different center to center distances of the nails; 150, 300 and 450 mm. fig. 6. shrinkage of the wooden batten and stud reduces the clamping effect by creating an air gap where air might leak. 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 450 mm 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 300 mm 0 20 40 60 80 100 120 initial dry 1 moist 1 dry 2 moist 2 dry 3 tape a ir le ak ag e, li tr e/ hm cc 150 mm meaning that the potential for creating an air gap like shown in fig. 6 is larger. other parameters that may affect the shrinkage (given the variation in yearly moisture content is the same) is the length of the nail and the design of the nail (surface texture etc). the effect of taping the overlap joint is relatively strong, reducing the air leakage with 58%, 39% and 22% for the cc 450 mm, cc 300 mm and cc 150 mm respectively. one could have expected that the taping should have reduced the air leakage close to the initial level before the first drying cycle, however this is far from happening. one possible explanation is that a large part of the air leakage during dry conditions is through the fixing holes of the nails through the vapour barrier. this is anyway an interesting finding even for cases when all the joints are taped, since there will always be a number of holes through the vapour barrier from the nails or screws. the configuration of fixing method when using wooden battens at the interior side of the vapour barrier may therefore be of interest even when taping of joints are used. numerical estimation for case buildings the estimated air leakage at 50 pa for the two case building is shown in fig. 7, based on the initial leakage, after the third drying cycle and after taping of the joint. in general we see much lower air change rate for the office building than the single family house. this is as expected since the office building have a much lower ratio between area of exterior walls and building volume, than the single-family house. if we compare with the maximum air leakage requirement of 0,6 1/h at 50 pa, we find that the leakage through the clamped joints (after the third drying) only accounts for between 6-15% (single family house) and 0,7-1,7% (office bulding) of the air leakage requirement. if we omit the results for the 450 mm nail distance, the air leakage accounts for between 6-8% (single family house) and 0,7-0,9% journal of sustainable architecture and civil engineering 2019/1/24 50 (office building) of the passive house requirement. this means that if the target value for airtightness for example is close to 0,6 1/h, the leakage through the clamped joints will not be critical in regard to reaching this goal. this especially applies for larger buildings with a low ratio between wall area and volume. if however the target value is closer to 0,2 1/h, the air leakage through the clamped joints is of growing relative importance, especially for smaller houses. from fig. 7 we also see that the relative improvement of taping the joint compared to an ordinary clamped joint is not big, especially for the larger building. the latest years, especially for passive houses projects in norway, we have seen air leakage numbers at 50 pa measured down to 0,1 0,2 1/h. these projects typically have extensive use of tape products at the vapour and wind barrier joints. the results of this study rise the question whether all this use of expensive tape products at the overlap joints are necessary, at least when a wooden battens anyway will be used at the interior side of the vapour barrier. fig. 7 estimated air leakage at 50 pa (normalized by volume) for the singlefamily house and office building. it is asumed there is no other leakage path than the clamped vapour barrier joints in the walls, see details in chapter “numerical estimation for case buildings” 3.2. numerical estimation for case buildings the estimated air leakage at 50 pa for the two case building is shown in fig. 7, based on the initial leakage, after the third drying cycle and after taping of the joint. in general we see much lower air change rate for the office building than the single family house. this is as expected since the office building have a much lower ratio between area of exterior walls and building volume, than the single-family house. if we compare with the maximum air leakage requirement of 0,6 1/h at 50 pa, we find that the leakage through the clamped joints (after the third drying) only accounts for between 6-15% (single family house) and 0,7-1,7% (office bulding) of the air leakage requirement. if we omit the results for the 450 mm nail distance, the air leakage accounts for between 6-8% (single family house) and 0,7-0,9% (office building) of the passive house requirement. this means that if the target value for airtightness for example is close to 0,6 1/h, the leakage through the clamped joints will not be critical in regard to reaching this goal. this especially applies for larger buildings with a low ratio between wall area and volume. if however the target value is closer to 0,2 1/h, the air leakage through the clamped joints is of growing relative importance, especially for smaller houses. from fig. 7 we also see that the relative improvement of taping the joint compared to an ordinary clamped joint is not big, especially for the larger building. the latest years, especially for passive houses projects in norway, we have seen air leakage numbers at 50 pa measured down to 0,1 0,2 1/h. these projects typically have extensive use of tape products at the vapour and wind barrier joints. the results of this study rise the question whether all this use of expensive tape products at the overlap joints are necessary, at least when a wooden battens anyway will be used at the interior side of the vapour barrier. fig. 7. estimated air leakage at 50 pa (normalized by volume) for the single-family house and office building. it is asumed there is no other leakage path than the clamped vapour barrier joints in the walls, see details in chapter 2.5. 4. conclusions this study has investigated whether and to what extent, repeated moisture cycles affect the air leakage through clamped overlaps in the vapour barrier layer. the results showed that the first drying cycle (from summer to winter conditions) resulted in significant increase of air leakage for all the sample variants. throughout the moisture cycles, a further strong leakage development for center to center nail spacing 0 0,02 0,04 0,06 0,08 0,1 cc 450 mm cc 350 mm cc 150 mm ai r ch an ge r at e (1 /h ) single-family house initial dry 3 tape 0 0,002 0,004 0,006 0,008 0,01 0,012 cc 450 mm cc 350 mm cc 150 mm ai r ch an ge r at e (1 /h ) office building initial dry 3 tape 3.2. numerical estimation for case buildings the estimated air leakage at 50 pa for the two case building is shown in fig. 7, based on the initial leakage, after the third drying cycle and after taping of the joint. in general we see much lower air change rate for the office building than the single family house. this is as expected since the office building have a much lower ratio between area of exterior walls and building volume, than the single-family house. if we compare with the maximum air leakage requirement of 0,6 1/h at 50 pa, we find that the leakage through the clamped joints (after the third drying) only accounts for between 6-15% (single family house) and 0,7-1,7% (office bulding) of the air leakage requirement. if we omit the results for the 450 mm nail distance, the air leakage accounts for between 6-8% (single family house) and 0,7-0,9% (office building) of the passive house requirement. this means that if the target value for airtightness for example is close to 0,6 1/h, the leakage through the clamped joints will not be critical in regard to reaching this goal. this especially applies for larger buildings with a low ratio between wall area and volume. if however the target value is closer to 0,2 1/h, the air leakage through the clamped joints is of growing relative importance, especially for smaller houses. from fig. 7 we also see that the relative improvement of taping the joint compared to an ordinary clamped joint is not big, especially for the larger building. the latest years, especially for passive houses projects in norway, we have seen air leakage numbers at 50 pa measured down to 0,1 0,2 1/h. these projects typically have extensive use of tape products at the vapour and wind barrier joints. the results of this study rise the question whether all this use of expensive tape products at the overlap joints are necessary, at least when a wooden battens anyway will be used at the interior side of the vapour barrier. fig. 7. estimated air leakage at 50 pa (normalized by volume) for the single-family house and office building. it is asumed there is no other leakage path than the clamped vapour barrier joints in the walls, see details in chapter 2.5. 4. conclusions this study has investigated whether and to what extent, repeated moisture cycles affect the air leakage through clamped overlaps in the vapour barrier layer. the results showed that the first drying cycle (from summer to winter conditions) resulted in significant increase of air leakage for all the sample variants. throughout the moisture cycles, a further strong leakage development for center to center nail spacing 0 0,02 0,04 0,06 0,08 0,1 cc 450 mm cc 350 mm cc 150 mm ai r ch an ge r at e (1 /h ) single-family house initial dry 3 tape 0 0,002 0,004 0,006 0,008 0,01 0,012 cc 450 mm cc 350 mm cc 150 mm ai r ch an ge r at e (1 /h ) office building initial dry 3 tape this study has investigated whether and to what extent, repeated moisture cycles affect the air leakage through clamped overlaps in the vapour barrier layer. the results showed that the first drying cycle (from summer to winter conditions) resulted in significant increase of air leakage for all the sample variants. throughout the moisture cycles, a further strong leakage development for center to center nail spacing 450 mm was observed, which was less for 300 mm, and non-existent for 150 mm. the gain of using structural adhesive tape was found to largely depend on the level of perforation resulting from the nails and their center distance. adhesive tape on the joints resulted in the greatest reduction in leakage numbers where the center distance between the nails was high, i.e. the reduction was 58% for center distance 450 mm. however, with shorter center distance the use of tape only decreased the air leakage between 22-39%, revealing the fact that a large part of the joint leakage is through the nail perforations. an estimation of the relative importance of air leakage through this type of overlap joints were made for a small and large type of building. the relative importance was not found to be big, since the estimated total air leakage through the overlap joints at 50 pa accounts only for between 6-8% (single family house) and 0,7-0,9% (office building) of the passive house requirement. the results also showed that although there is a positive effect of taping the overlap joint, the effect seems to be reduced by air leakages through the fixing holes of the nails through the vapour barrier. conclusions references aho, h., vinha, j., korpi, m. (2008). implementation of airtight constructions and joints in residential buildings. in the nordic journal of building physics, the 8th symposium on building physics in the nordic countries june (vol. 16). airaksinen, m., pasanen p. o, kurnitski j., seppänen o. (2003). “microbial contamination of indoor air due 51 journal of sustainable architecture and civil engineering 2019/1/24 to leakages from crawl space: a field study.” indoor air 14: 55-64. https://doi.org/10.1046/j.16000668.2003.00210.x bracke, w., van den bossche n.., janssens a. (2014). airtightness of building penetrations: air sealing solutions, durability effects and measurement uncertainty. 35th conference: ventilation and airtightness in transforming the building stock to high performance (aivc-2014), aivc. epbd, c. a. (2016). “implementing the energy performance in buildings directive (epbd).” ca epbd iii, lisbon, portugal: ca epbd. en12114 (2000) thermal performance of buildings air permeability of building components and building elements laboratory test method. standard norge geving, s. and holme j. (2012) “mean and diurnal indoor air himidity loads in residential buildings.” journal of building physics 35 (4): 392-421. https:// doi.org/10.1177/1744259111423084 gullbrekken l, bergby j.c, geving s, et al. (2012a) measurements of air leakage through clamped joints. 7th international buildair symposium. stuttgart. germany gullbrekken l, bergby j.c, uvsløkk s, et al. (2012b) improvement of traditional clamped joints in vapour and wind barrier layer for passive house design. passivhus norden conference. trondheim. norway janssens, a. and h. hens (2003). “interstitial condensation due to air leakage: a sensitivity analysis.” journal of thermal envelope and building science 27(1): 1529. https://doi.org/10.1177/1097196303027001002 kalamees, t., alev ü., pärnalaas m (2017). “air leakage levels in timber frame building envelope joints.” building and environment 116: 121-129. https://doi. org/10.1016/j.buildenv.2017.02.011 künzel, h. m., (1995) simultaneous heat and moisture transport in buildings components – oneand two-dimensional calculation using simple parameters. (phd). irb verlag, germany. relander, t.o., holøs s. and thue j. v. (2012). “airtightness estimation—a state of the art review and an en route upper limit evaluation principle to increase the chances that wood-frame houses with a vapour-and wind-barrier comply with the airtightness requirements.” energy and buildings 54: 444452. https://doi.org/10.1016/j.enbuild.2012.07.012 tek17 (2017). forskrift om tekniske krav til byggverk. [regulations on technical requirements for buildings]. kommunal og moderniseringsdepartementet. oslo. norway. (in norwegian) tuominen, p., r. holopainen, l. eskola, j. jokisalo, m. airaksinen (2014). “calculation method and tool for assessing energy consumption in the building stock.” building and environment 75: 153-160. https://doi.org/10.1016/j.buildenv.2014.02.001 stig geving professor norwegian university of science and technology, dept. of building and environmental technology main research area heat and moisture transfer in buildings and building components, with a special emphasis on envelope design, moisture simulations, moisture damages and practical moisture handling in the building process. building physical issues in regard to energy retrofits and energy efficient buildings such as passive houses and zero energy buildings has also been a focus the recent years address høgskoleringen 7a, no-7491 trondheim, norway tel. +47-92299576 e-mail: stig.geving@ntnu.no øyvind norvik msc student (during execution of laboratory study) norwegian university of science and technology, dept. of building and environmental technology main research area airtightness of vapour barrier joints address høgskoleringen 7a, no-7491 trondheim, norway tel. +47-90924412 e-mail: oyvind.norvik@kjellmark.no lars gullbrekken researcher sintef building and infrastructure, no-7491 trondheim, norway main research area heat and moisture transfer in buildings and building components, with special emphasis on ventilated sloped wooden roofs, airtightness of wind and vapour barrier address høgskoleringen 7b, no-7491 trondheim, norway tel. +47-45474324 e-mail: lars.gullbrekken@sintef.no about the authors 53 journal of sustainable architecture and civil engineering 2020/2/27 *corresponding author: eng.fp@frederick.ac.cy an overview of the existing schemes and research trends in financing the energy upgrade of buildings in europe received 2020/03/10 accepted after revision 2020/06/21 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 53-62 doi 10.5755/j01.sace.27.2.25465 an overview of the existing schemes and research trends in financing the energy upgrade of buildings in europe jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.25465 christiana panteli frederick university, cyprus, school of engineering, 7, y. frederickou str. pallouriotisa, nicosia 1036 cyprus cleopa gmbh, neuendorfstr. 18b lt-16761 hennigsdorf, germany eglė klumbytė, rasa apanavičienė kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania paris a. fokaides* frederick university, cyprus, school of engineering, 7, y. frederickou str. pallouriotisa, nicosia 1036 cyprus kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania financial supporting schemes for the energy upgrading of the building sector in europe constitute one of the major policies of the european union (eu). since the beginning of the 2000s, dozens of funding programs and initiatives have been announced by the european commission (ec). it is a fact that the majority of these policies have borne fruit, as the metrics on both energy savings in the building sector and the promotion of renewable energy in the built environment have turned the eu into a global pioneer. this paper attempts to give a brief overview of the main policy and financial tools for the energy upgrading of the built environment in europe. emphasis is placed on three major mechanisms, which concern different-scale projects: crowdfunding projects, public-private co-financing projects, and large-scale projects funded by financial institutions such as european investment bank (eib). some of the significant findings of this study revealed that the energy-related funding schemes penetration defers in european member states in terms of advancement and implementation status. reference is also made to recently implemented eu funded research programs in this field. this work aspires to constitute a reference study for future research activities in the field of financial supporting schemes for energy upgrading of buildings in europe. keywords: funding schemes, crowdfunding, public-private-partnership, energy upgrade, buildings, energy efficiency. journal of sustainable architecture and civil engineering 2020/2/27 54 introduction ec european commission epbd energy performance of buildings directive ppp public-private partnership eib european investment bank epcs energy performance certificates sfsb smart finance for smart buildings pda project development assistance ets emission trading scheme the 2012 energy efficiency directive established and mandate a set of measures dedicated to the achievement of the 20% energy efficiency target by 2020 (ec 2012). according to the directive, the european union (eu) countries are required to improve energy efficiency in all stages of the energy chain. on 30th november 2016, the european commission (ec) amended the energy efficiency directive to include a new energy efficiency target of a 30% reduction in energy by 2030. individual national energy efficiency targets and action plans have been set from european union (eu) countries to achieve the eu’s 2020 target. the recently revised (december 2018) energy performance of buildings directive (epbd) is the main legislative instrument developed to realize the savings potential in the buildings sector targeting the long term decarbonization of the eu buildings stock (ec 2010). given that the buildings account for almost 40% of the eu energy consumption, the importance of the implementation of ebbd is vital for achieving eu energy savings and carbon emission targets as well as to contribute to the kyoto protocol targets. the concerted action epbd is the board established by the european commission in order to capitalize on, and foster, the directive’s implementation in the 28 member states (ec 2020). early efforts concentrated on energy performance certificates (epcs) – who could use them, their form and content, and keeping track of them even after implementation. later, however, issues gradually emerged – how good and reliable were they? could they be used for informed decisions related to investment? was there to be any quality control and enforcement by authorities, or was this just another piece of paper that someone needed to obtain and include in a purely administrative check, if any? these still partially open questions are creating room for improvements. according to dovjak and kukec, 2019 (dovjak & kukec 2019), the consumption of heating oil between new and old building varies substantially with new buildings considered more effective (3-5 l/m2/year) compared to older buildings (25-60 l/m2/year). currently, about 35% of europe’s buildings are more than 50 years old. improving the energy efficiency of the existing building stock will significantly reduce energy consumption and co2 emissions (ec 2020b). the scope of this study is to present a comprehensive overview of the existing funding schemes in the eu for the energy upgrade of buildings. following the introductory part, the study presents some crucial aspects of the european energy policy in the field, presenting some major supporting instruments. an analysis of the funding schemes in three different levels, according to the scale of investment, is presented in the third section of the study. particularly the study analyses funding schemes for small scale projects (crowdfunding), mid-scale projects (public-private partnership ppp), and large-scale projects funded by european investment bank (eib) and other funding institutions. the main findings of the study are presented in the conclusions section. list of abbreviations ppas power purchase agreements esco energy service companies epc energy performance contracting eersf energy efficiency and renewable sources fund eeef european energy efficiency fund erdf the european regional development fund jessica the joint european support for sustainable investment in city areas elena the european local energy assistance 55 journal of sustainable architecture and civil engineering 2020/2/27 under the existing epbd, the following measures must be applied: _ buildings offered for rental or sale should enclose energy performance certificates (epcs); _ eu member states must establish inspection schemes of heating and air conditioning systems or measures with equivalent effect; _ all the newly constructed buildings should be nearly zero-energy by 31 st december 2020 (after 31 december 2018 for new public buildings occupied and owned by public authorities); _ eu member states must establish national minimum energy performance requirements for new buildings, for the major renovation of buildings, and the replacement or retrofitting of building elements; and _ eu member states should prepare national financial measures for improving the energy efficiency of the building sector. the eu has released different support schemes and financial programs for the successful implementation of energy efficiency projects (pyrgou et, al. 2016, kylili & fokaides 2015, fokaides & kylili 2014). even though the eu has increased the public finance dedicated to energy efficiency, public funds alone are not sufficient for a clean energy transition. infor this transition to happen, there is a need to trigger private energy efficiency investments. in this perspective, in 2018, the ec has released the smart finance for smart buildings (sfsb) initiative under ‘clean energy for all europeans’ communication as an effort to mobilize private financing on renewables sources and energy efficiency in buildings. the sfsb initiative aims to reinforced longer-term investments on energy projects in the building sector by allocating €18 billion between 2014 and 2020. the current investment status lacks motivation from the investors resulting in low energy renovation rates (~1% /year) (ec 2019), while financial institutions arrange loans based on credits and property values discouraging the vulnerable consumers from investing in energy efficiency measures. to change these practices, sfsb target in three main goals: _ to trigger private investments in energy efficiency through the intelligent use of eu grants as a guarantee. as part of the sfsb initiative, the commission in conjunction with eib, developed the ‘’guarantee facility’’ model under which the financial institutions can benefit from partial coverage of financial losses (70%) when they deal with the uncertainty of innovative energy projects. this flexible model allows the development of innovative financing programs for the energy renovation of buildings by commercial banks or other intermediaries. _ help investors and financial institutions to assess the risks associated with energy investments as well as the obtained benefits by providing the de-risking energy efficiency platform (deep 2020). the platform is an open-source database that contains data on energy efficiency projects, including monitoring, benchmarking and risk assessments. the users can use the platform to gain insights on energy investments risks based on real data, benchmark their projects compared to others as well as contribute for database enrichment _ offer technical and financial support to private and public building owners to implement investments in ambitious energy projects by setting up project development assistance (pda) facilities such as elena and pda h2020. elena is managed by the eib and provides financial support to large-scale energy-related projects above €30 million. the pda h2020 supports the development of small and medium-scale energy projects of at least €7.5 million. the latest development concerning funding schemes developed by the eu for its member states concerns the innovation fund (ec 2020c) (see fig. 1). this initiative constitutes a financial support program that origins out of the eu emission trading scheme (ets). the rationale behind this project is that part of the revenues, which results from carbon trading in the eu, will be invested in innovative projects related to the decarbonisation of the eu economy. the processor of the innovation fund is the ner300, which allowed the investment of over 2 billion eur in the eu from overview of the eu policy for the energy upgrade of buildings in europe journal of sustainable architecture and civil engineering 2020/2/27 56 5 fig. 1 the innovation fund (2020-2030) of the european union for investments for the decarbonization of the european market the latest development concerning funding schemes developed by the eu for its member states concerns the innovation fund (ec 2020c) (see fig. 1). this initiative constitutes a financial support program that origins out of the eu emission trading scheme (ets). the rationale behind this project is that part of the revenues, which results from carbon trading in the eu, will be invested in innovative projects related to the decarbonisation of the eu economy. the processor of the innovation fund is the ner300, which allowed the investment of over 2 billion eur in the eu from 2012 to 2019. the new funding scheme is 5 times larger compared to its predecessor, and its scope is much wider, emphasizing the field of energy storage, as well as on energy intensive industries. the commission also established the ‘’eu building stock observatory’’ which is used to track and publish energy performance related indicators of buildings across europe (ec 2020d). 3.funding schemes for the energy upgrade of buildings in europe in this section, an overview of the main funding schemes in europe for different scale projects is presented. particularly funding schemes for small-scale projects initiated by the private sector (crowdfunding), medium scale projects in which the private and public sector collaborate (ppp) and large-scale project funded by the public sector are presented. the analysed schemes, as well as their relation with the private and the public sector, are depicted in fig. 2. the rationale of the study is that funding is classified in three levels of investment bottom layer investments are represented by a crowdfunding methodology for project of small entity (of max interventions of €100,000). second layer investments are proposed for medium size projects (up to €2 m) using public – private partnership (ppp) solution while for large scale projects, top investments layer concerns funding opportunities at the european level (eg eib) 2012 to 2019. the new funding scheme is 5 times larger compared to its predecessor, and its scope is much wider, emphasizing the field of energy storage, as well as on energy intensive industries. the commission also established the ‘’eu building stock observatory’’ which is used to track and publish energy performance related indicators of buildings across europe (ec 2020d). in this section, an overview of the main funding schemes in europe for different scale projects is presented. particularly funding schemes for small-scale projects initiated by the private sector (crowdfunding), medium scale projects in which the private and public sector collaborate (ppp) and large-scale project funded by the public sector are presented. the analysed schemes, as well as their relation with the private and the public sector, are depicted in fig. 2. the rationale of the study is that funding is classified in three levels of investment: _ bottom layer investments are represented by a crowdfunding methodology for project of small entity (of max interventions of €100,000). _ second layer investments are proposed for medium size projects (up to €2 m) using public – private partnership (ppp) solution while for large scale projects, _ top investments layer concerns funding opportunities at the european level (eg eib) crowdfunding crowdfunding is considered to be an alternative practice of raising finance through standardized online processes. the crowdfunding has grown exponentially since 2012 to have considerable advantages compared to traditional financial instruments (candelise, 2015). traditionally, financing a project will require a large investments from a few individuals who will invest a large amount of money. crowdfunding adopts a different mechanism that engages a large number of possible funders who are willing to invest in the implementation of a project or idea through the internet. the users have the option to choose among different investment options, therefore, covering different financial status. the online process of collecting the finances increases the speed of transacfig. 1 the innovation fund (2020-2030) of the european union for investments for the decarbonization of the european market funding schemes for the energy upgrade of buildings in europe fig. 2 energy upgrade funding schemes of the private and public sector, versus the scale of the project 6 fig. 2 energy upgrade funding schemes of the private and public sector, versus the scale of the project 3.1 crowdfunding crowdfunding is considered to be an alternative practice of raising finance through standardized online processes. the crowdfunding has grown exponentially since 2012 to have considerable advantages compared to traditional financial instruments (candelise, 2015). traditionally, financing a project will require a large investments from a few individuals who will invest a large amount of money. crowdfunding adopts a different mechanism that engages a large number of possible funders who are willing to invest in the implementation of a project or idea through the internet. the users have the option to choose among different investment options, therefore, covering different financial status. the online process of collecting the finances increases the speed of transaction processing and the rate of raising funds. this has led to the discussion of whether such an alternative finance tool could be used in energy efficiency investments towards cleaner energy systems. beyond an alternative method for raising funds, crowdfunding allows communities and citizens to become shareholders and share investments on energy projects (cf4ee 2020). these approaches unlock new business models and can change the role of passive consumers to producers allowing citizens and individuals to become shareholders and benefit from the return on the investment. a presentation of crowdfunding’s rationale is depicted in fig. 3. currently, the existing crowdfunding platforms for environmental campaigns mostly dominated by renewable energy projects. the most famous among the renewables are the photovoltaic and wind projects followed to a lesser extent by biomass and hydropower. nonetheless, the degree of which this alternative financing method could be exploited still remains far from its full potential, especially for energy efficiency projects. as analysed and found out by other eu-funded projects such as citizenergy and crowdfundres, there are significant barriers preventing individuals from understanding and investing through alternative financing mechanisms. local authorities can play a significant role in bridging public and alternative financial tools, given that the combination of such an investment will be a far more efficient technic of financing energy projects. this combination will enable ambitious energy tion processing and the rate of raising funds. this has led to the discussion of whether such an alternative finance tool could be used in energy efficiency investments towards cleaner energy systems. beyond an alternative method for raising funds, crowdfunding allows communities and citizens to become shareholders and share investments on ener57 journal of sustainable architecture and civil engineering 2020/2/27 fig. 3 the major steps of crowdfunding of projects for energy upgrade of buildings 7 projects to be implemented using citizen’s collaboration while accelerating the implementation of eu’s energy targets. fig. 3. the major steps of crowdfunding of projects for energy upgrade of buildings 3.2 public-private partnerships (ppps) public-private partnerships (ppps) is the collaboration of public and private sector for the purpose to implement public projects to use the resources and expertise of the private sector. ppps allow largescale government projects to be implemented in cases where the public sector is facing capital intensive projects, or more efficient services are required. the collaboration with the private sector can bring new solutions and finance, while the risks and responsibilities are being shared. this collaboration enables governments to focus on policy, planning, and regulation and the public sector to benefit from receiving the operating profits once the project is complete (savas & savas, 2000). fig. 4 represents the main stages of ppp projects. in the energy sector, the main public-private agreements concern clean technology and energy efficiency and energy and power. in the first sector, renewable energies, power purchase agreements (ppas) and carbon capture and storage are included, whereas, in the latter, ppas, including transmission, distribution, and fuel supply are found. according to the ‘’review of the european ppp market in 2018’’ published by the european investment bank, the value of ppp investments in eu market in 2018 was eur 14.6 billion, of which seven projects were implemented in the environment and energy sector for a total value of eur 2 billion (eib 2020). while the number of ppps in the energy sector that reached financial close has been relatively low in the last couple of years, their potential and impact are undoubtedly high. moreover, the participation of energy service companies (escos) in ppp projects can be of high added value for ppp studies due to their focussed know-how, a high degree of specialisation and innovativeness. such examples of successful projects are the berlin energy saving partnerships and hungary “szemünk fenye program”. the first refers to the successful retrofit for public buildings initiated in berlin in cooperation with berlin energy agency (bea). based on energy performance contracting (epc) mechanisms and joint collaboration with escos, a 26% energy gy projects (cf4ee 2020). these approaches unlock new business models and can change the role of passive consumers to producers allowing citizens and individuals to become shareholders and benefit from the return on the investment. a presentation of crowdfunding’s rationale is depicted in fig. 3. currently, the existing crowdfunding platforms for environmental campaigns mostly dominated by renewable energy projects. the most famous among the renewables are the photovoltaic and wind projects followed to a lesser extent by biomass and hydropower. nonetheless, the degree of which this alternative financing method could be exploited still remains far from its full potential, especially for energy efficiency projects. as analysed and found out by other eu-funded projects such as citizenergy and crowdfundres, there are significant barriers preventing individuals from understanding and investing through alternative financing mechanisms. local authorities can play a significant role in bridging public and alternative financial tools, given that the combination of such an investment will be a far more efficient technic of financing energy projects. this combination will enable ambitious energy projects to be implemented using citizen’s collaboration while accelerating the implementation of eu’s energy targets. public-private partnerships (ppps) public-private partnerships (ppps) is the collaboration of public and private sector for the purpose to implement public projects to use the resources and expertise of the private sector. ppps allow large-scale government projects to be implemented in cases where the public sector is facing capital intensive projects, or more efficient services are required. the collaboration with the private sector can bring new solutions and finance, while the risks and responsibilities are being shared. this collaboration enables governments to focus on policy, planning, and regulation and the public sector to benefit from receiving the operating profits once the project is complete (savas & savas, 2000). fig. 4 represents the main stages of ppp projects. fig. 4 the major steps of private-public-partnership for medium-scale projects related to energy upgrade of buildings 8 efficiency improvement was achieved over 1,400 successfully renovated buildings. similarly, the “szemünk fenye program” upgraded the indoor-lighting and heat supply in municipal and educational institutions in hungary, based on multiyear service contracts (‘szemünk fenye program 2020). the best value-for-money esco provider was selected by the ministry of education, based on specific criteria such as pricing, experience, terms of the financial package, etc. similar successful projects such as ‘energy efficiency and renewable sources fund’ (eersf) are also documented in bulgaria. fig. 4. the major steps of private-public-partnership for medium-scale projects related to energy upgrade of buildings 3.3 eu public funds for energy efficiency the ambitious targets set by the eu concerning the energy efficiency under the objectives of the 2020 and 2030 energy packages, aroused the need to increase the number of measures towards the clean energy transition. in this perspective, the number of public funds needed for the period 2021-2030 to reach the eu's energy and climate objectives for 2030 will be €177 billion per year (ec 2015). currently, there are more than 60 eu funds available (euro funding database) concerning the energy sector, in which the most well-known are the european energy efficiency fund (eeef), the european regional development fund (erdf), the joint european support for sustainable investment in city areas (jessica) and the european local energy assistance (elena). § the european energy efficiency fund (eeef) (ec 2020e) is an initiative between the european commission, the european investment bank (eib), the cassa depositi e prestiti (cdp), and deutsche bank. eeef aims to support the eu target towards clean energy transition by providing financing to public projects related to energy saving and efficiency, renewable energy, and clean urban transport projects. beneficiaries of the fund could also be private entities in collaboration with public authorities § the european regional development fund (erdf) (ec 2020f) is a financial instrument under the eu cohesion policy planning to deploy €20 billion from 2014-2020. this funding instrument aims to reduce regional disparities among different eu regions and to reinforce economic growth, sustainable development, and job creation. the joint european support for sustainable journal of sustainable architecture and civil engineering 2020/2/27 58 in the energy sector, the main public-private agreements concern clean technology and energy efficiency and energy and power. in the first sector, renewable energies, power purchase agreements (ppas) and carbon capture and storage are included, whereas, in the latter, ppas, including transmission, distribution, and fuel supply are found. according to the ‘’review of the european ppp market in 2018’’ published by the european investment bank, the value of ppp investments in eu market in 2018 was eur 14.6 billion, of which seven projects were implemented in the environment and energy sector for a total value of eur 2 billion (eib 2020). while the number of ppps in the energy sector that reached financial close has been relatively low in the last couple of years, their potential and impact are undoubtedly high. moreover, the participation of energy service companies (escos) in ppp projects can be of high added value for ppp studies due to their focussed know-how, a high degree of specialisation and innovativeness. such examples of successful projects are the berlin energy saving partnerships and hungary “szemünk fenye program”. the first refers to the successful retrofit for public buildings initiated in berlin in cooperation with berlin energy agency (bea). based on energy performance contracting (epc) mechanisms and joint collaboration with escos, a 26% energy efficiency improvement was achieved over 1,400 successfully renovated buildings. similarly, the “szemünk fenye program” upgraded the indoor-lighting and heat supply in municipal and educational institutions in hungary, based on multiyear service contracts (‘szemünk fenye program 2020). the best value-for-money esco provider was selected by the ministry of education, based on specific criteria such as pricing, experience, terms of the financial package, etc. similar successful projects such as ‘energy efficiency and renewable sources fund’ (eersf) are also documented in bulgaria. eu public funds for energy efficiency the ambitious targets set by the eu concerning the energy efficiency under the objectives of the 2020 and 2030 energy packages, aroused the need to increase the number of measures towards the clean energy transition. in this perspective, the number of public funds needed for the period 2021-2030 to reach the eu’s energy and climate objectives for 2030 will be €177 billion per year (ec 2015). currently, there are more than 60 eu funds available (euro funding database) concerning the energy sector, in which the most well-known are the european energy efficiency fund (eeef), the european regional development fund (erdf), the joint european support for sustainable investment in city areas (jessica) and the european local energy assistance (elena). _ the european energy efficiency fund (eeef) (ec 2020e) is an initiative between the european commission, the european investment bank (eib), the cassa depositi e prestiti (cdp), and deutsche bank. eeef aims to support the eu target towards clean energy transition by providing financing to public projects related to energy saving and efficiency, renewable energy, and clean urban transport projects. beneficiaries of the fund could also be private entities in collaboration with public authorities _ the european regional development fund (erdf) (ec 2020f) is a financial instrument under the eu cohesion policy planning to deploy €20 billion from 2014-2020. this funding instrument aims to reduce regional disparities among different eu regions and to reinforce economic growth, sustainable development, and job creation. the joint european support for sustainable investment in city areas (jessica) (ec 2020g) is an initiative by the european commission in collaboration with the european investment bank (eib) and the council of europe development bank (ceb) to support sustainable urban development. jessica supports investments financially on sustainable urban-renewal projects within the european union with the option of using some of the eu structural funds. 59 journal of sustainable architecture and civil engineering 2020/2/27 research projects for financial schemes for the energy upgrade of buildings _ the european local energy assistance (elena) (eib 2020b) is a joint initiative by the eib and the european commission for technical and economic assistance on projects related to energy efficiency, renewable energy, and urban transport programs. elena supports projects above €30 million and covers up to 90% of technical assistance/project development costs. as of may 2019, 56 projects are ongoing under the elena fund, of which 1 in lithuania, 1 in greece, 3 in germany, 4 in germany, and 4 in poland. the ec is supporting several projects in the context of development and roll-out of innovative energy efficiency financing services. among them, the following had the highest impact on the development of the financing schemes for energy projects support in the eu: 1. citynvest – increasing the capacity in cities for innovative financing of energy efficiency (citynvest 2015-2018). this project strives to introduce innovative financing models in three pilot regions and to conduct a broad capacity-building program in 10 countries, related to specific financial instruments/business models. 2. citizee – citizen financing for energy efficiency (citizee 2019-2022). this project strives to support european public authorities to increase energy efficiency in the building sector by attracting private investments through crowdfunding and cooperative financing schemes. 3. enpc-intrans – capacity-building in energy performance contracting in european markets in transition (enpc-intrans 2015-2017). this project aspired to increase the use of technologies used to support energy efficiency in public buildings. this goal was achieved by the joint collaboration of public authorities and smes in setting-up and use adapted enpc models for ee services. 4. eesi 2020 – the european energy service initiative towards the eu 2020 energy-saving targets (eesi 2020), which aimed at fostering the use of energy performance contracting in major cities and metropolitan regions across europe. 5. enerfund an energy retrofit funding rating tool (enerfund 2016-2019). this project has developed a tool for identifying in-depth renovation opportunities based on different parameters such as epc data, the number of certified installers, governmental schemes are running, etc. the aim was to enable building owners to make smart energy renovation decisions. 6. crowdfundres unleashing the potential of crowdfunding for financing renewable energy projects (crowdfundres 2015-2018). provides different layers of promotion (i.e., definition of toolkits/guidelines/recommendations for a wide range of stakeholders such as project’s promoters/holders, project’s backers/investors, definition of case studies, organisation and delivery of engagement events for selected stakeholders and general public) of crowdfunding as a financing tool for energy efficiency projects 7. citizenergy the european platform for citizen investment in renewable energy (citizenergy 2014-2017). this project allows european citizens to participate in the eu’s energy mix by giving them a chance invest in renewable energy projects of their own decision. under this eu funded project, an eu res platform has been developed in which the european citizens can financially contribute and connect with each other 8. enershift – social housing innovative financing tender for energy (enershift 2016-2020). this project aimed at energy renovation public housing in liguria through innovative financing mechanisms by launching tenders for esco’s energy performance contracting (epc) and low public fund an overview of the eu funded research projects implemented from 2015 onwards for the upgrade of the energy performance of buildings is provided in table 1. journal of sustainable architecture and civil engineering 2020/2/27 60 project brief description implementation period coordinator citynvest (2015-2018) supports the energy renovation of public buildings and introduction of innovative financing models in three regions: belgium, bulgaria and spain. the citynvest project document the successful financing models applied in the euroepan union and create new models based on energy performance contracting (epc), third party financing (tpf), revolving funds, cooperatives and others 2015 2018 climate alliance klima-buendnis alianza del clima e.v. citizee (2019-2022) citizee is a european funded project in the context of h2020 aimed to increase the energy efficiency investments in the building sector. the project supports public authorities to develop attractive financial models to trigger private investments 2019-2022 wirtschaft und infrastruktur gmbh & co planungs kg enpc-intrans (2015-2017) this h2020 european funded project aspired to increase the use of technologies used to support energy efficiency in public buildings. this goal was achieved by the joint collaboration of public authorities and smes in setting-up and use adapted enpc models for ee services 2015-2017 deutsche gesellschaft fur internationale zusammenarbeit (giz) gmbh eesi 2020 this european funded project supports the energy plans of nine major cities and metropolitan regions in europe by enabling the long term implementation of energy performance contracting (epc) 2013-2016 berliner energieagentur gmbh enerfund (2016-2019) enerfund is a european funded project which assesses deep renovation opportunities in buildings by developing a rating tool based on a set of parameters such as: epc data, number of certified installers, governmental schemes running, etc 2016-2019 technologiko panepistimio kyprou crowdfundres (2015-2018) crowdfundres supports the development of renewable energy investments in european union by enabling the use of crowdfunding. this european funded project brings together three target groups: renewable energy project developers, crowdfunding platforms and public. 2015-2018 wirtschaft und infrastruktur gmbh & co planungs kg citizenergy (2014-2017) this project allows european citizens to participate in eu’s energy mix by give them the chance invest in renewable energy projects of their own decision. under this eu funded project, an eu res platform has been developed in which the european citizens can financially contribute and connect with each other 2014-2017 ateknea solutions catalonia enershift (2016-2020) this eu funded project aims to trigger energy retrofitting of social housing in liguria region by launching tenders for esco’s energy performance contracting (epc) and low public fund. 2016-2020 regione liguria table 1 overview of eu funded research projects implemented from 2015 onwards for the upgrade of the energy performance of buildings 61 journal of sustainable architecture and civil engineering 2020/2/27 references the purpose of this study was to present the main financing tools for the energy upgrading of buildings in europe. particular emphasis was placed both on the presentation of european policy and the analysis of crowdfunding, ppp, and public financing instruments. this work may form the basis for further research activities in the field of energy upgrades of buildings in europe. some of the significant findings of this study revealed that the energy-related funding schemes penetration defers in european member states in terms of advancement and implementation status. taking, for example, the 56 projects which are currently implemented in terms of the elena funding scheme, only 2 are realized in the three baltic eu member states, and just one in the post-2008 eu member states (bulgaria, romania, croatia). the situation is similar for southern eu member states, with just 1 project being implemented in greece, cyprus, malta, and portugal. on the other hand, countries like denmark, germany or the netherlands present high numbers in elena projects (8, 4 and 4 respectively). the numbers are similar for other funding schemes related to buildings energy efficiency. it goes without saying that if no concrete actions are taken in this field, the gap between south-eastern europe on the one hand and central-north europe on the other will be increasing. as an important parameter that must be stated in the stage is the national energy efficiency financial mechanisms of eu ms. no country can ignore the development, social and economic opportunities that are being unleashed by relevant energy efficiency policies and measures around the world. therefore eu member states must be give primary consideration in national energy policies and energy efficiency financial schemes that should be integrated into mainstream economic planning of local government and business development processes in general. the imperative norm that any project idea to be implemented in this field should consider this chasm and take the appropriate actions to boost the economic 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(2015). competitive auction mechanisms for the promotion renewable energy technologies: the case of the 50 mw photovoltaics projects in cyprus. renewable and sustainable energy reviews, 42, 226-233.https://doi.org/10.1016/j.rser.2014.10.022 pyrgou, a., kylili, a., & fokaides, p. a. (2016). the future of the feed-in tariff (fit) scheme in europe: the case of photovoltaics. energy policy, 95, 94-102https://doi.org/10.1016/j.enpol.2016.04.048 savas, e. s., & savas, e. s. (2000). privatization and public-private partnerships. about the authors christiana panteli research associate in cleopa gmbh and a phd student frederick university, cyprus, school of engineering main research area energy and buildings, digital construction design tools address neuendorfstr. 18b lt-16761 hennigsdorf, germany tel.: +49 3302 / 2069295 e-mail: cpanteli@cleopa.de eglė klumbytė lecturer kaunas university of technology, faculty of civil engineering and architecture main research area construction management, building sustainability address 48, studentu str., 51367, kaunas, lithuania tel.: +370 (37) 300 000 e-mail: egle.klumbyte@ktu.lt rasa apanavičienė associate professor kaunas university of technology, faculty of civil engineering and architecture main research area construction management, building sustainability address 48, studentu str., 51367, kaunas, lithuania tel.: +370 (37) 300 000 e-mail: rasa.apanaviciene@ktu.lt paris fokaides assistant professor frederick university, cyprus, school of engineering, and a chief researcher at kaunas university of technology, faculty of civil engineering and architecture main research area sustainable energy systems, energy and buildings address 7, frederickou str., 1036, nicosia, cyprus tel.: +35722 394394 e-mail: eng.fp@frederick.ac.cy this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 52 clay based poultices for desalination of building materials janina setina1*, svetlana kirilova1 1riga technical university, azenes 14/24, riga lv-1048, latvia * corresponding author: janina@ktf.rtu.lv one of the major threats affecting the lifetime of cultural monuments and residential buildings are the water-soluble salts raising the necessity for desalination activities. in the following paper three clay-based compositions have been studied by varying ratio of binder (clay) to filler (sand and cellulose) as follows: clay to sand mass ratio 1:2, 1:5 and clay/sand/cellulose mass ratio of 1:4,5:0,5. the experimental examination of desalination compositions included determination of density, drying shrinkage, pore size distribution using mercury porosimetry before and after exposure to the solutions of water soluble salts. in order to control desalination process quantitative and qualitative analysis of ions of soluble salts (distribution profiles of nitrate, chloride and sulphate ions as well as crystalline phases of the samples by using chemical and xrd analysis) in both material – poultice, as well as salinated building material have been performed. the obtained results have shown that the main parameter determining salt transport mechanisms and desalination efficiency is pore size distribution of the substrate and poultice as well as nature and ratio of the binder and filler. obtained experimental data can be used for further research as well as planning of practical restoration activities in environments with high concentration of water-soluble salts. keywords: clay-based poultices, building materials, desalination. darnioji architektūra ir statyba 2012. no. 1(1) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction deterioration of the natural and artificial stone materials used in industrial and historical constructions is caused by the simultaneous interaction of different factors such as environmental contamination, weather (humidity, freeze and thaw etc.) and presence of different water-soluble salts. solutions of salts may crystallize in pores of the stone material causing an increased pressure and formation of micro-cracks or interact chemically with material constituents (carretero et al. 2006). therefore, a large part of the preventative and restoration activities are devoted to decreasing the salt concentration in building materials. different methods are available for this purpose depending on particular environmental conditions, physical and chemical properties of the contaminated object as well as its historical background. the most common desalination technique is desalination poultices made of a mixture of clay minerals (zeolite, kaolinite or bentonite), sand and cellulose (lubelli and hees 2010). desalination process can be performed by two main mechanisms: diffusion and advection. the pore size distribution and volume of the pores both in substrate and poultice plays an important role in desalination process. in order to achieve fast and effective desalination it is recommended to perform it by the advection mechanism with simultaneous wetting function. in order to achieve it pore size distribution must be broad, i. e. poultice has to contain both small pores which provide salt extraction and large reservoir pores which provide wetting of the substrate (lubelli and hees 2010). even though this method is attractive due to its simplicity, effective desalination and use of local raw materials, more explicit examination of desalination mechanisms is necessary. the desalination process normally consists of two major stages, i. e. selection and studies of desalination composition and control of desalination process. in the first step the material with the highest ability to adsorb common soluble salts causing stone disintegration such as chlorides, sulphates and nitrates is chosen depending on a particular masonry and object subjected for desalination. the control of desalination process is performed by quantitative and qualitative analysis of the salt ion concentration in different height and depth of both desalination poultice as well as contaminated building material (setina et al. 2009). the following paper reflects the studies concerning properties and desalination ability of clay based poultices applied to an artificial stone material, low temperature burned brick “sencis”, contaminated with water soluble sodium salts, i. e. chlorides, sulphates and nitrates as well as modelling of desalination process in laboratory conditions. http://dx.doi.org/10.5755/j01.sace.1.1.2618 53 2. methods the current study has been elaborated in two stages: selection and examination of clay based desalination compositions and control of desalination process. three clay based compositions have been studied by varying ratio of binder (clay) and filler (sand and cellulose) as follows: clay to sand ratio 1:2, 1:5 and clay/sand/cellulose ratio of 1:4, 5:0,5. the following compositions have been chosen based on results found in literature (lombardo and simon, 2006) in order to study the effect of the addition of cellulose compared to the clay/sand mixture traditionally used for desalination of historical monuments in latvia (krage et al. 2006). the quaternary clay from broceni (latvia) was used for experiments. the pure clay was used as a reference for the studied desalination compositions. the specimens with above mentioned compositions were prepared in a rectangular shape (20x25x54 mm). after drying and hardening in a room temperature volume and density of the specimens was calculated based on their weight and size (table 1). table 1. physical properties of different clay based composition weight, g v, cm3 ρ, g/cm3 clay 39,6 25,61 1,54 clay/sand 1:2 59,9 29,36 2,04 clay/sand 1:5 55,3 32,72 1,69 clay/sand/cellulose 1:4,5:0,5 38,98 30,99 1,26 the dynamics of the drying were studied by monitoring the weight loss of the specimens with different binder to filler ratios. after hardening the drying shrinkage was determined. the functional serving time of the poultice is determined by these properties. porosity of the specimens was determined by mercury porosimetry (autopore iv). the mineralogical composition of broceni clay and sand was analysed by x-ray powder diffraction (difractometer rigaku optima plus) using cukα radiation. the second step of investigations included desalination of artificially salinated brick “sencis” (produced in factory “lode”) by application of tested clay based poultices in order to evaluate and compare their desalination ability. prior to the experiment, brick was salinated with the solutions of nacl, nano3, na2so4 for 90 days. in order to allow the diffusion of salt solution only in one direction e. g. only through one of the rectangular faces of salinated specimen, the five other sides were covered with paraffin. the uncovered faces of salinated samples were coated with a 2 cm thick layer of a clay based poultice. salt extraction has been monitored in depth of 10mm both in removed poultice and the treated brick using chemical analysis and x-ray diffraction (xrd). chemical analysis has been performed using merckoquant® test strips (paper chromatography) for determination of so42-, no3and cl ions in the samples of interest. 3. results and discussion properties of the clay based poultice study of the drying process showed that clay specimens with admixture of sand (1:2 and 1:5) exhibit shorter drying time (2 days) compared to the pure clay and a mixture of clay, sand and cellulose (3 days) (fig. 1). however, the lowest drying shrinkage was observed for the compositions with higher proportion of the filler, i. e. clay/sand mixture with the ratio of 1:5 and clay/sand/ cellulose mixture with the ratio of 1:4, 5:0,5 (table 2). table 2. drying shrinkage of different clay based compositions composition drying shrinkage (%) clay 6,42 clay/sand 1:2 5,13 clay/sand 1:5 4,63 clay/sand/cellulose 1:4,5:0,5 4,92 results obtained from mercury porosimetry performed for the clay based samples with different binder to filler j. setina, s. kirilova 63 table 2. drying shrinkage of different clay based compositions composition drying shrinkage (%) clay 6,42 clay/sand 1:2 5,13 clay/sand 1:5 4,63 clay/sand/cellulose 1:4,5:0,5 4,92 fig. 1. weight loss due to drying in time for the specimens with different binder to filler ratio results obtained from mercury porosimetry performed for the clay based samples with different binder to filler ratios showed that clay samples without additives mainly contain pores in a size range from 0,01 to 0,2 µm (fig. 2). fig. 2. pore size distribution for the clay sample without additives samples with clay/sand ratio of 1:5 exhibit two main pore size ranges – from 0,01 to 0,4 µm and from 2 to 20 µm (fig.3). fig. 1. weight loss due to drying in time for the specimens with different binder to filler ratio 54 ratios showed that clay samples without additives mainly contain pores in a size range from 0,01 to 0,2 µm (fig. 2). fig. 2. pore size distribution for the clay sample without additives samples with clay/sand ratio of 1:5 exhibit two main pore size ranges – from 0,01 to 0,4 µm and from 2 to 20 µm (fig.3). fig. 3. pore size distribution for the samples with clay/sand ratio of 1:5 finally, mixture of clay, sand and cellulose exhibits a broad pore size distribution but the main fraction is in the range from 3 to 500 µm (fig. 4). crystalline phases determined by x-ray diffraction for broceni clay are kaolinite, illite, calcite, dolomite and quartz. sand contains mainly quartz. fig. 4. pore size distribution for the samples with clay/sand/ cellulose ratio of 1:4, 5:0,5 properties of the contaminated substrate as mentioned, a building material typical for latvian cultural heritage was selected for artificial salination and desalination in laboratory conditions – low temperature burned brick „sencis” with the properties close to historical bricks. the average porosity of brick is 23–24 % and density – 1.80 g/cm3. the results obtained from the xrd performed for the brick “sencis” before salination indicated such crystalline phases as spinel (mgal2o4), quartz (sio2), hematite (fe2o3), and microcline (kalsi3o8). after exposure to salt solutions for 90 days same crystalline phases were determined as before salination and additionally thenardite (na2so4) and mirabilite (na2so4·10h2o) for the samples exposed to 0,1 m na2so4 solution, halite (nacl) for the samples exposed to 1 m nacl solution and sodium nitrate (nano3) for the samples exposed to 1 m nano3 solution. as it can be seen salts do not interact with the material since no products of chemical interaction were determined by xrd. chemical analysis using merckoquant® test strips was performed for the brick before and after exposure to salt solutions in different depths (fig. 5). it can be seen that salts are mainly concentrated next to the surface of the brick (1-15 mm depth). nitrate ions exhibit very low concentration compared to sulphate and chloride ions. modeling of desalination process according to the methodology of desalination described before, one surface of salinated brick was covered with 2 cm thick layer of lime mortar. clay based poultice 55 was kept wet for 20 days. after drying and removal of application the amount of cl, no3and so42ions were analysed both in clay-based poultice as well as desalinated material in 10 mm depth. results of chemical analysis for the brick and poultice after desalination are given in table 3 and table 4 respectively. it can be seen that the concentration of water soluble salts in substrate decreases drastically after application of the clay based poulticessulphate ions are completely removed whereas only traces of chloride ions and low concentrations of nitrate ions are present in substrate after desalination. chemical analysis of the poultice after removal from the contaminated substrate shows that concentration of the salts is significant in the poultices (table 4). xrd analysis of the poultices before and after applying them to the substrate have been performed in order to observe migration of the water soluble salts from contaminated substrate into the poultice. the results show that before application main crystalline phases of the clay/sand mixture 1:5 were quartz, plagioclase, calcite, dolomite and illite (fig. 6). after removal of the application from the substrate contaminated with water-soluble salts, the crystalline phases determined by x-ray diffraction were identical to the ones in the mixture of origin and additionally the crystalline phases of water soluble salts have been observed (fig. 7). all studied compositions showed acceptable desalination efficiency and thus can be used for desalination of the brick “sencis” however the most economically feasible options are the compositions with higher ratio of filler, e. g. clay/sand ratio of 1:5 and clay/sand/cellulose ratio of 1:4, 5:0,5. the latter composition exhibited longer drying time and it has a better adhesion with substrate due to cellulose armature and low mass. however, an advantage of the poultice with clay/sand ratio of 1:5 is its relatively low drying shrinkage which is an important parameter for the desalination poultices. j. setina, s. kirilova 65 samples exposed to 1 m nano 3 solution. as it can be seen salts do not interact with the material since no products of chemical interaction were determined by xrd. chemical analysis using merckoquant® test strips was performed for the brick before and after exposure to salt solutions in different depths (fig. 5). fig. 5. results of chemical analysis for the brick “sencis” after exposure to the salt solutions for 90 days in different depths it can be seen that salts are mainly concentrated next to the surface of the brick (1-15 mm depth). nitrate ions exhibit very low concentration compared to sulphate and chloride ions. modeling of desalination process according to the methodology of desalination described before, one surface of salinated brick was covered with 2 cm thick layer of lime mortar. clay based poultice was kept wet for 20 days. after drying and removal of application the amount of cl , no 3 and so 4 2 ions were analysed both in clay-based poultice as well as desalinated material in 10 mm depth. results of chemical analysis for the brick and poultice after desalination are given in table 3 and table 4 respectively. table 3. concentration of salt ions in brick “sencis” before and after desalination using clay-based poultices salt ions before desalination after desalination (brick in 10 mm depth) clay/sand 1:2 clay/sand 1:5 clay/sand/cellulose 1:4,5:0,5 cl (mg/l) 2700 50 traces traces so 4 2 (mg/l) 1800 0 0 0 no 3 (mg/l) 50 10 <10 <10 it can be seen that the concentration of water soluble salts in substrate decreases drastically after application of the clay based poulticessulphate ions are completely removed whereas only traces of chloride ions and low concentrations of nitrate ions are present in substrate after desalination. chemical analysis of the poultice after removal from the contaminated substrate shows that concentration of the salts is significant in the poultices (table 4). table 4. concentration of salt ions in clay based poultices after desalination salt ions poultices after desalination (in 10mm depth) poultices after desalination (in 10mm depth) clay/sand 1:5 clay/sand/cellulose 1:4,5:0,5 cl (mg/l) 1500 2300 2500 so 4 2 (mg/l) 1200 1500 1500 no 3 (mg/l) 10 25 25 xrd analysis of the poultices before and after applying them to the substrate have been performed in order to observe migration of the water soluble salts from contaminated substrate into the poultice. the results show fig. 5. results of chemical analysis for the brick “sencis” after exposure to the salt solutions for 90 days in different depths table 3. concentration of salt ions in brick “sencis” before and after desalination using clay-based poultices salt ions before desalination after desalination (brick in 10 mm depth) clay/sand 1:2 clay/sand 1:5 clay/sand/cellulose 1:4,5:0,5 cl(mg/l) 2700 50 traces traces so42(mg/l) 1800 0 0 0 no3(mg/l) 50 10 <10 <10 table 4. concentration of salt ions in clay based poultices after desalination salt ions poultices after desalination (in 10mm depth) poultices after desalination (in 10mm depth) clay/sand 1:5 clay/sand/cellulose 1:4, 5:0,5 cl(mg/l) 1500 2300 2500 so42(mg/l) 1200 1500 1500 no3(mg/l) 10 25 25 56 chemical analysis performed for the poultices after desalination (table 4) showed rather high concentration of cl-, so42and no3ions. xrd analysis demonstrated the presence of the crystalline phases of the salts in a clay based poultice removed from the contaminated substrate which confirms the migration of salts from the substrate into the poultice. thus, the salt ions are transported from the salinated substrate to the poultice and accumulate in it. xrd analyses of desalinated brick in different depth did not show presence of the crystalline salts as nacl, na2so4, nano3 which confirms the efficiency of the studied clay based compositions. 4. conclusions the compositions with broceni clay/sand ratio of 1:2 and 1:5 as well as clay/sand/cellulose ratio 1:4, 5:0,5 have been studied. the results obtained in the following study have shown that the main parameter determining salt transport mechanisms and desalination efficiency is pore size distribution of the substrate and poultice as well as nature and ratio of the binder and filler. the compositions with higher binder to filler ratio exhibit broader pore size distribution and higher desalination efficiency. based on obtained results clay based application with clay/sand/cellulose ratio of 1:4, 5:0,5 and clay/sand ratio of 1:5 can be recommended as effective desalination compositions. obtained experimental data can be used for further research for desalination of different construction materials as well as planning of practical restoration activities in environments with high concentration of water-soluble salts. clay based poultices for desalination of building materials 66 that before application main crystalline phases of the clay/sand mixture 1:5 were quartz, plagioclase, calcite, dolomite and illite (fig. 6). fig. 6. difractogram for the clay/sand 1:5 mixture before application on contaminated substrate after removal of the application from the substrate contaminated with water-soluble salts, the crystalline phases determined by x-ray diffraction were identical to the ones in the mixture of origin and additionally the crystalline phases of water soluble salts have been observed (fig. 7). fig. 7. difractogram for the clay/sand 1:5 mixture after removal from the substrate contaminated with 0,1 m nano 3 all studied compositions showed acceptable desalination efficiency and thus can be used for desalination of the brick “sencis” however the most economically feasible options are the compositions with higher ratio of filler, e.g. clay/sand ratio of 1:5 and clay/sand/cellulose ratio of 1:4,5:0,5. the latter composition exhibited longer drying time and it has a better adhesion with substrate due to cellulose armature and low mass. however, an advantage of the poultice with clay/sand ratio of 1:5 is its relatively low drying shrinkage which is an important parameter for the desalination poultices. chemical analysis performed for the poultices after desalination (table 4) showed rather high concentration of cl , so 4 2 and no 3 ions. xrd analysis demonstrated the presence of the crystalline phases of the salts in a clay based poultice removed from the contaminated substrate which confirms the migration of salts from the substrate into the poultice. thus, the salt ions are transported from the salinated substrate to the poultice and accumulate in it. xrd analyses of desalinated brick in different depth did not show presence of the crystalline salts as nacl, na 2 so 4 , nano 3 which confirms the efficiency of the studied clay based compositions. 4. conclusions the compositions with broceni clay/sand ratio of 1:2 and 1:5 as well as clay/sand/cellulose ratio 1:4,5:0,5 have been studied. fig. 6. difractogram for the clay/sand 1:5 mixture before application on contaminated substrate clay based poultices for desalination of building materials 66 that before application main crystalline phases of the clay/sand mixture 1:5 were quartz, plagioclase, calcite, dolomite and illite (fig. 6). fig. 6. difractogram for the clay/sand 1:5 mixture before application on contaminated substrate after removal of the application from the substrate contaminated with water-soluble salts, the crystalline phases determined by x-ray diffraction were identical to the ones in the mixture of origin and additionally the crystalline phases of water soluble salts have been observed (fig. 7). fig. 7. difractogram for the clay/sand 1:5 mixture after removal from the substrate contaminated with 0,1 m nano 3 all studied compositions showed acceptable desalination efficiency and thus can be used for desalination of the brick “sencis” however the most economically feasible options are the compositions with higher ratio of filler, e.g. clay/sand ratio of 1:5 and clay/sand/cellulose ratio of 1:4,5:0,5. the latter composition exhibited longer drying time and it has a better adhesion with substrate due to cellulose armature and low mass. however, an advantage of the poultice with clay/sand ratio of 1:5 is its relatively low drying shrinkage which is an important parameter for the desalination poultices. chemical analysis performed for the poultices after desalination (table 4) showed rather high concentration of cl , so 4 2 and no 3 ions. xrd analysis demonstrated the presence of the crystalline phases of the salts in a clay based poultice removed from the contaminated substrate which confirms the migration of salts from the substrate into the poultice. thus, the salt ions are transported from the salinated substrate to the poultice and accumulate in it. xrd analyses of desalinated brick in different depth did not show presence of the crystalline salts as nacl, na 2 so 4 , nano 3 which confirms the efficiency of the studied clay based compositions. 4. conclusions the compositions with broceni clay/sand ratio of 1:2 and 1:5 as well as clay/sand/cellulose ratio 1:4,5:0,5 have been studied. fig. 7. difractogram for the clay/sand 1:5 mixture after removal from the substrate contaminated with 0,1 m nano3 57 acknowledgements the research work was carried out in the frame of erdf project „high performance nanoconcretes” (no2010/0286/2dp/2.1.1.1.0/10/apia/viaa/033). references carretero, m. i., barnabé, j. m., galán, e. (2006). application of sepiolite-cellulose pastes for the removal of salts from building stones. applied clay science, 33, 43-51. krage, l., vitina, i., ingune, s., sidraba, i. (2006). desalination of stone objects in latvia. in: proceedings of the arcchip workshops, 2006. vol.5, 287-294. lombardo, t., simon, s. (2006). laboratory study on desalination by poultices. european research on cultural heritage, 5. lubelli, b., van hees, r. p. j. (2010). desalination of mansonry structres: fine tuning of pore size distribution of poultices to substrate properties. journal of cultural heritage, 11, 10-18. setina, j., krage, l., svare, j., kirilova, s. (2009). simulation of desalination processes using lime based mortars. chemine technologija, 1, 30-36. received 2012 08 09 accepted after revision 2012 09 03 janina setina – senior research scientist at riga technical university, institute of silicate materials. main research area: cement, concrete science and technology. address: azenes str. 14/24, riga lv-1048, latvia riga technical university, institute of silicate materials. tel.: +371 29674640 e-mail: janina@ktf.rtu.lv svetlana kirilova – chemical technologist. main research area: cement, concrete science and technology; glass science and technology. address: cempu 13, valmiera lv-4201, latvia valmiera glass fiber jsc plc. tel.: +371 25445385 e-mail: svetlanak@vss.lv 26 ecology of city: levels and components mindaugas staniūnas1* 1 vilnius gediminas technical university, faculty of environmental engineering, sauletekio ave. 11, lt-10223 vilnius, lithuania * corresponding author: mindaugas.staniunas@vgtu.lt currently, more than half of the world‘s population live in urban areas and thus cities have become areas of intensive intersections of interests. as a major place for business, living and gathering cities (via citizens) create great pressure on nature; thus, cities can be treated as “battlefields” particularly considering citizens needs and environment. the article discusses current conception of “ecology of a city” at different scales while highlighting the need of a comprehensive approach. a two layer method is proposed, i. e., 1) global and 2) local stages according to which cities can be regarded as: 1) exporters of ecological burden and 2) internal producers of pollution. although both processes are interrelated and intertwined separate responsible components of each layer are extracted: at a global level the main input from cities comes from energy and waste management sectors while at a local level the key problems are air pollution and noise. the article argues that ecological assessment necessary in urban planning should be done based on aforementioned scheme and calls for the development of it. keywords: urban ecology, level, component, assessment, impact. darnioji architektūra ir statyba 2012. no. 1(1) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction urban ecology is a phenomenon that gets lots of attention nowadays; it attracts developers and investors, politicians and citizens, manufacturers and users, stakeholders and professionals with a different interest. to some extent cities and environment or combination of both can be identified not only as a very common issue but at the same time virtually fashionable. “urban”, “ecology” and their derivatives are the labels often to be stuck on almost everything; for instance, urban clothing, music, environmentally friendly products, eco-driving, ecodistricts, sustainability, etc. urbanization studies constantly increases and although urbanization can be studied from different perspectives (e. g. social, economic) according to a recent research, the major subject categories are environmental sciences, ecology, environmental studies, etc. (wang et al. 2012). there are many drivers of the topic, but the key drivers promoting discussions are likely to be only two: 1) the rapid growth of the world population and 2) environmental changes it causes. increasing population is a recent process that started in 1950, from then on (i. e. within 60 years) the world population more than doubled: the united nations populations fund (unfpa) reports that there are 7 billion people in the world and other billion is soon expected (unfpa 2011). furthermore, the world becomes more and more urban in character and cities are growing almost everywhere: more than half of the world’s population lives in cities and in about 35 years additional 25% is expected (unfpa 2011). this issue is especially vital in developed regions, for instance, in the european union (eu) 68% of the total population already live in urban areas (eurostat, 2011). hence, assuming global trends it can be prognosticated that cities will remain the major places of living and human activities (pickett et al. 2011). human activities inevitably cause disturbances of the environment unnatural environmental series of changes are other actor that attracts majority of attention. this issue is a double-sided and can be analysed from two perspectives: on the one hand people are responsible for environmental changes (e. g. loss of biodiversity, land degradation) but on the other hand these environmental changes simultaneously affect people life (e. g. floods, uv radiation). world health organization (who) groups health impacts into three parts: 1) direct (e. g. water shortage, heat waves), 2) “ecosystemmediated” (e. g. mental health, reduced food yields) and 3) indirect health impacts (e. g. population displacement conflict, inappropriate adaptation and mitigation) (who 2012). having in mind that majority the world’s population lives in cities all these procedures are extremely important in urban areas. furthermore, in essence cities face similar environmental problems such as poor air quality, high levels of traffic and ambient noise, greenhouse gas emissions, generation of waste, etc. (ec 2006). basically, cities combine urban, environmental and social issues at the same time and in one place, hence, the concept of sustainability is touched. a complex issue and http://dx.doi.org/10.5755/j01.sace.1.1.2614 27 numerous attempts to solve it has done unsuspected damage, which is well spotted out by macgregor-fors (2011): “synonyms of basic urban ecology terms have been used by researches to describe different environmental conditions, while similar conditions are often describes using diverse terms”. as a result there are articles that are devoted solely for reviewing of various environmental indicators (böhringer and jochem 2007; singh et al. 2009). lastly, more than 20 years passed but sustainable development was not realized anywhere (millennium ecosystem assessment 2005). the article aims to describe “ecology of a city” from an urban planner’s perspective: an urbanist is one of the key persons that are responsible for urban development, hence, future of a city. however, the article aims to consider solely about “ecology of a city” and thus firstly it seeks to analyse what is a difference between sustainability in general and its ecological “ingredient”. secondly, it tries to sort city’s ecology in accordance with impact it has on the environment. finally, an aggregated scheme for understanding of city’s ecology is proposed. 2. sustainability vs. ecology already has been mentioned that sustainable development has not been realized anywhere (millennium ecosystem assessment, 2005) logically one can assume that the same situation occurs with all its compounds, i. e. economy, society and ecology and thus that means that there is no possible solution. a model that works in practice does not exist so it is impossible to find it. however, the question is not unresolvable – the solution does exist because of crucial difference between sustainability in general and its compounds separately. such statement requires further explanation and a comprehensive context. speaking about sustainability in general and its constantly failing implementation in practice, one can hypothesize that it occurs due to the nature of a process, i. e. its flexibility. that means that sustainability is not a fixed and final result, which once reached will last forever. regularly new issues and problems arise echoing a normallife set of series of actions (e. g. environmental conditions, human needs, political systems, etc.) which continually develops. that is to say that what was right and important yesterday may not be valid and essential today. furthermore, in a real world dynamics of processes are strengthened and accelerated by large sustainability’s concept and thus the problems that arise cannot be answered right away. for instance, if emission (pollution) of greenhouse gases were stabilized today, concentration of carbon dioxide (co2) in the atmosphere (it is crucial for global environmental changes) would stabilize only after 100-300 years and a sea level rise due to melting of glaciers would last for thousand years (aresta 2010; ipcc, 2007a). the same lagging is common to other sustainability components, for example, if in libya investments in education, drinking water infrastructure, etc. were made after changes in politics everything has to be started over again. therefore, in practice a delay is an integral part of sustainable development; it is a constant process occurring continuously over a period of time and thus perpetual alterations have to be done (fig. 1 upper curve). and exactly at this point, i. e. the action of correcting something, sustainability in general is different from its separate elements. it is extremely well noticeable if environmental issue is considered. cogitating about environment specialists highlight irreversibility, i. e. in the real world an absolute environmental limit exists, which once crossed leads into changes that cannot be undone or altered. for instance, currently such situation occurs with some plant/animal species that are put on the edge of extinction. a finite result is essentially different from dynamical and flexible process of sustainability: when the limit is reached any contraactions become meaningless and negotiations are already impossible (fig. 1 lower curve). this fact is neatly presented by albert arnold gore (a former vice president of the united states and democratic party presidential candidate; nobel peace prize laureate in 2007) in a documentary “an inconvenient truth”. the scene (77 minute) shows scales that balances two different things: on the one side there are gold bars and on the other side – the entire planet. at that very moment a. gore ponders that such weighting is a false choice for two reasons from which the first is – “if we don’t have a planet…” hence, the major aim considering ecological compound of sustainability is not to “lose”, i. e. do not over abuse the planet and do not exceed the critical level. this task remains within any field of actions and urban planning is not an exception, it is a subcomponent of a larger global ecology. the meaning of the word “ecology” was significantly modified since its introduction in the xix century: it changed from an exceptionally biological science to a much broader field incorporating other areas of natural and non-natural sciences (wittig 2009) and thus currently four different meanings of the term can be recognised (haila and levins 1992). m. staniūnas 32 fig. 1. sustainability vs. ecology the concept “urban ecology” is a compound of two terms and as a result it is a complex concept that has different dimensions. in essence urban ecology is an applied science (niemelä, kotze and yli-pelkonen 2009) and this branch of ecology can be used on two different levels depending on the standpoint (alberti et al. 2003; wittig 2009, pickett et al. 2011). the first – natural science level describes ecosystems in cities in terms of biophysical, ecological, etc. processes, i.e. area of biology that is concerned with cities. the second one – political and urban planning level – describes issues of urban design programmes, planning the environmental amenities of cities for people and mitigation of negative environmental impacts of cities. strictly speaking the main object of urban ecology is urban ecosystems, which are densely populated and has a high degree of built structures and infrastructure, thus it does not incorporate the remote areas affected by energy and material transformations generated in urban core (pickett et al., 2011; wittig, 2009). ecological scholars (alberti et al. 2003, grimm et al. 2000, mcdonnell et al. 2009) have been highlighting the shortcomings of traditional (narrow) conception of urban ecology for some time already: basically, current studies analyses how urban territories alter natural environment, what influence these territories have on particular species (animals, birds, plants, etc.) or compare urban ecosystems with suburban. in other words, it means that humans (i.e. citizens) a priori are treated as “something” that hovers somewhere above, is exceptional, not typical, single and having minimal contact. this conception is very narrow-minded because reality is clearly different: in fact, the cities are mostly affected by citizens but not somebody else (e.g. birds, frogs, trees, etc.). ecologists even call the cities “a human dominated ecosystem” (vitousek et al. 1997). therefore, in a broader sense urban ecology includes less densely populated areas (for instance, sparsely settled villages) and integrates various areas of science, political decisions and planning that improve living conditions but simultaneously alter environment (alberti et al. 2003, wittig 2009, pickett et al. 2011). and although from traditional standpoint the boundaries of urban ecosystems are often set by administrative units in practice many occurring processes extend beyond these boundaries: they affect other areas directly as well as remotely (alberti et al. 2003, pickett et al. 2011). hence, if artificial limitation on issue is not the aim, then urban ecology (or ecology of cities) has to be evaluated comprehensively, in a full context, dealing with all aspects and especially paying attention to citizens – a propulsive element of the system. following the above mentioned logic it seems useful to take glance at the most important ecological problems at a global scale. probably in a global ecological context it will become clear what is “input” of cities and what is important for cities. that will present compounds of the broader understanding, when cities are treated as 1) an outer, external player as well as discusses about 2) what and how affects city’s “inner” ecology, i.e. what is substantial for a city not globally but locally, within its boundary. it is important to highlight that the paper aims at urban planning issues but not at biology field. 3. “inner” and “outer” ecology identification of the world’s worst ecological issue is not very hard; however, with one exception. even the worst and obvious problems can be criticized and diminished depending on one’s point of view, that is to say that everything is relative. therefore, a double-checking practice was used in this article and a statement was assessed two times: firstly, it is checked if the statement is endorsed by the experts in general and, secondly, it is checked if there are any facts that validate it. if the majority of experts agree upon the phenomenon and there are facts proving the accuracy then it is believed that the phenomenon is correct. such an assessment is not officially binding, but author believes it is the most proper one. fig. 1. sustainability vs. ecology the concept “urban ecology” is a compound of two terms and as a result it is a complex concept that has different dimensions. in essence urban ecology is an applied science (niemelä, kotze and yli-pelkonen 2009) and this branch of ecology can be used on two different levels depending on the standpoint (alberti et al. 2003; wittig 2009, 28 pickett et al. 2011). the first – natural science level – describes ecosystems in cities in terms of biophysical, ecological, etc. processes, i. e. area of biology that is concerned with cities. the second one – political and urban planning level – describes issues of urban design programmes, planning the environmental amenities of cities for people and mitigation of negative environmental impacts of cities. strictly speaking the main object of urban ecology is urban ecosystems, which are densely populated and has a high degree of built structures and infrastructure, thus it does not incorporate the remote areas affected by energy and material transformations generated in urban core (pickett et al., 2011; wittig, 2009). ecological scholars (alberti et al. 2003, grimm et al. 2000, mcdonnell et al. 2009) have been highlighting the shortcomings of traditional (narrow) conception of urban ecology for some time already: basically, current studies analyses how urban territories alter natural environment, what influence these territories have on particular species (animals, birds, plants, etc.) or compare urban ecosystems with suburban. in other words, it means that humans (i. e. citizens) a priori are treated as “something” that hovers somewhere above, is exceptional, not typical, single and having minimal contact. this conception is very narrow-minded because reality is clearly different: in fact, the cities are mostly affected by citizens but not somebody else (e. g. birds, frogs, trees, etc.). ecologists even call the cities “a human dominated ecosystem” (vitousek et al. 1997). therefore, in a broader sense urban ecology includes less densely populated areas (for instance, sparsely settled villages) and integrates various areas of science, political decisions and planning that improve living conditions but simultaneously alter environment (alberti et al. 2003, wittig 2009, pickett et al. 2011). and although from traditional standpoint the boundaries of urban ecosystems are often set by administrative units in practice many occurring processes extend beyond these boundaries: they affect other areas directly as well as remotely (alberti et al. 2003, pickett et al. 2011). hence, if artificial limitation on issue is not the aim, then urban ecology (or ecology of cities) has to be evaluated comprehensively, in a full context, dealing with all aspects and especially paying attention to citizens – a propulsive element of the system. following the above mentioned logic it seems useful to take glance at the most important ecological problems at a global scale. probably in a global ecological context it will become clear what is “input” of cities and what is important for cities. that will present compounds of the broader understanding, when cities are treated as 1) an outer, external player as well as discusses about 2) what and how affects city’s “inner” ecology, i. e. what is substantial for a city not globally but locally, within its boundary. it is important to highlight that the paper aims at urban planning issues but not at biology field. 3. “inner” and “outer” ecology identification of the world’s worst ecological issue is not very hard; however, with one exception. even the worst and obvious problems can be criticized and diminished depending on one’s point of view, that is to say that everything is relative. therefore, a double-checking practice was used in this article and a statement was assessed two times: firstly, it is checked if the statement is endorsed by the experts in general and, secondly, it is checked if there are any facts that validate it. if the majority of experts agree upon the phenomenon and there are facts proving the accuracy – then it is believed that the phenomenon is correct. such an assessment is not officially binding, but author believes it is the most proper one. hence, the world’s greatest ecological problem (in general it is acknowledged and facts exist) is global climate change, frequently described as a threat to humanity’s future (ipcc, 2007b, mcmichael et al. 2003, unep, unicef, who, 2002, parry, 2007). in general, climate change itself is not dangerous: it is resonant turn of events that is so much important, for instance, temperature extremes, droughts, floods, etc. and in recent decades majority of problems are caused by global warming. global warming or to be more precise increasing concentration of greenhouse gases is caused by many anthropogenic activities, e. g. industrial processes or farming. various activities are responsible for different gases; however, in the world as well as in the european union the biggest share of emission belongs to carbon dioxide and methane. in 2004 carbon dioxide amounted up to 77% and methane – 14% of the world’s total greenhouse gas emission; in 2009 in the eu (eu-27) 80% of emission belonged to carbon dioxide and 9% to methane (barker et al. 2007, unfcc, 2009). at a global scale from 1970 until 2004 (only in 34 years) emission of carbon dioxide and methane increased by 80% and 40% respectively (barker et al. 2007). the above mentioned information should help reflecting upon the raised question: “what is “input” of cities”? in general, it is clear that an answer must be connected with greenhouse gas emission particularly its management (decline). in other words it should answer how cities can mitigate its input to global warming. however, if practical implementation is a target then it is required to know who, where and why generates emission. although the intergovernmental panel on climate change (ipcc) indicates a few sectors that are extremely responsible for greenhouse gas emission, for instance, energy, industrial processes or waste management, a unique global understanding does not exist: various international organizations give slightly different descriptions. basically, the difference lies in aggregation process because various operations can be counted in several sectors, for example, transport can be assigned to energy sector but on the other hand taking into account today’s importance and intensity of the sector it can be treated individually. however, in accordance with the reports of the most influential international organizations (e. g. ipcc, oecd, un), the most responsible sector contributing to global greenhouse gas emission is energy sector. the same situation is in the eu where energy sector is responsible for 80% of the total greenhouse gas emission, further goes agriculture (10%), industrial processes (7%), waste management (3%) and solvents (unfccc, 2009). therefore, “outer” ecology of a city is nothing more but greenhouse gas emission, which is generated in order to fulfil city’s energy demand and thus the objective of “outer” 29 ecology is city’s energy management. carbon dioxide plus methane are two gases that make 89% of the total eu emission; hence, management of these gases must get the biggest attention. tracing that the major polluter in cities is energy sector is not very hard – statistical information shows a strong gap between energy and other sectors. a recorded gap has other advantage: being so big it clearly indicates the key problem; nevertheless, it is hard to indicate other (second, third, etc.) responsible activities. it is to say that further top-bottom approach will not give clear and unambiguous results: difference between emissions wanes, sectorial dependency fades, etc. however, seeking for solutions applicable to practice a common concept and unified action plan are required. it must be highlighted that speaking about ecological simulation of cities such unanimous indicators have not existed for a very long time. slightly more than a decade ago in 1999 the eu started an international project – the european common indicators initiative – which focused on helping local authorities monitor environmental sustainability of its urban environment (tarzia 2003). such practical aim required moderate number of indicators and thus only the key ones were selected. the final set consists of merely 10 indicators, which in principle are applicable to any city of the union. last but not least important is the fact that initiative tried to involve as much participants as possible starting from experts, governmental, eu and national institutions and finishing with public. the organisation for economic co-operation and development (oecd) also supports the idea of minimizing the number of indicators and gives a felicitous explanation: a shorter list with basic indicators is easier understandable for public and thus ensures a clear and tight cooperation between local authority and citizens (oecd 2008). actually, “easier understandable” means literally “understandable” because in most cases people simply do not know about city’s future, they are unable to read the information. the above mentioned list consists of the following indicators: 1) citizen satisfaction with the local community, 2) local contribution to global climatic change, 3) local mobility and passenger transportation, 4) availability of local public open areas and services, 5) quality of local ambient air, 6) children’s journey’s to and from school, 7) sustainable management of the local authority and local business, 8) noise pollution, 9) sustainable land use and 10) products promoting sustainability (ec, 2012). the aim of the initiative was vast, cumulative and touching sustainability issue as a whole; hence, not all indicators are concerned with ecology. exceptional relations with climate change has only one indicator (i. e. the second: local contribution to global climatic change) and it validates the earlier discussed logical sequence. a special methodology was developed for indicators and thus following the description of the second indicator 4 key stones can be selected. they will benefit to the further development of city’s ecology. first and one of the most important tasks is determining a city’s “input”, contribution to global climatic changes. in this particular case we speak about identification of further (going after energy sector) elements that remained unclear before. the methodology confirms that many sectors are responsible for greenhouse gas emission; however “the energy sector, together with the waste management sector, represent the main focus for action by the local authority” (ec 2012), i. e. it is affirmed that considering ecology of city there are only two – the energy and the waste management – sectors that are really important. the waste management sector is responsible for 3% of the total emission but even 3/4 of the gases come from landfills (unfccc, 2009) and thus this is a sector, which is much easier and cheaper to manage than, for instance, industrial processes. moreover, it is worth noting that implementing kyoto’s flexible mechanisms the most common ones are related to these two sectors: the lion’s share of projects (about 67%) are in energy industries while the second place (about 14%) is taken by waste handling and disposal (unfccc 2012). secondly, the methodology quite explicitly discloses the energy sector, i. e. analyses its elements. the energy sector is particularly different if compared to the waste management sector because it consists of many parts (e. g. energy generation and demand in industry, households, transportation, etc.) and thus to determine these single elements would be a time consuming procedure. furthermore, a threat exist that in such case integrity will be lost and it would be very unfavourable for urban planning procedures. upholding entirety of the concept the methodology suggests disaggregation of the energy sector based on consumption analysis; hence, there are 4 parts: 1) residential, 2) commercial, 3) industrial and 4) transportation. thirdly, if cities are being analysed in a context of global ecological issues one crucial fact becomes evident: any city occupies a limited plot of land, i. e. it has administrative boundaries; ecological problems behave totally differently as they do not “know” boundaries. therefore, the methodology proposes substitution of geographical/ administrative limitations with responsibility and thus two new phrases arise: “debt emissions” and “credit emissions”. for instance, a city consumes energy for street lighting and although the energy comes from a power plant that is far away from the city this emissions should be assigned to the city. it is its demand and requirement that is to say its “debt emissions”. the model works vice versa, for example, if a big city has waste incineration plant it can “import” wastes from other cities and gain “credits”. the final assessment should involve three stages: 1) emission that is generated within geographical/administrative boundary plus 2) “debt emissions” and minus 3) “credit emission”. lastly, the question about values arises. in general, when referring to boundaries absolute values are being used; however, the methodology stresses the importance of comparative values. normally lots of actions and procedures that occur in a city are not manageable with common urban planning tools, for instance, wind turbines contribute to the use of renewables, but they can be erected only on sites that favour adequate wind. hence, the methodology proposes to use absolute and comparative values simultaneously and additionally monitor alteration of emissions. further discussing about city’s ecological framework it is useful to remember a question that was raised at the outset, i. e. what is important for cities and why cities 30 are important? in essence the question consists of two elements: inner and outer impact. the above mentioned indicator supplements the main “culprit” (i. e. the energy sector) with the waste sector and explains the second part of the question enough comprehensively. that means that in cities these two sectors are mainly responsible for global warming or to be more precise not the sectors themselves but the emissions. the phrase “enough comprehensively” means that speaking about ecological issues at global scale extremely precise result is not necessary (and probably not possible) and proper management of only two sectors could help achieving good results. however, the first part of a question is still not answered, i. e. what is important for cities, for their inner life and processes? there is a huge difference between “inner” and “outer” city life: things important in a city can be completely nonessential at a global scale and vice versa. to illustrate such independence two examples are discussed. for instance, a main street of a city with 100000 citizens runs through living districts. due to constant and intensive traffic flow people that live near that street are exposed to a high level of noise and have poor air quality. that means that living conditions in these districts are dangerous and habitants suffer from disturbances. however, at a global scale greenhouse gas emission from a traffic fleet of 100000 cars (a car for each inhabitant) is statistically insignificant. as already has been mentioned this model works on contrary too. for example, due to global warming droughts become more frequent in africa and thus it becomes harder to get an access to drinking water, water shortage occurs. meanwhile a huge problem in africa (locally) this issue is physically not perceptible for citizens of industrialized countries and thus is not important for most of them. citizens of the usa or the eu can simply open water tap whenever they need water or worse – to buy a bottle of water. it can be stated that each city has individual character and its processes are somewhat unique. nevertheless, if practical implementation is the aim then a common understanding and action plan are the necessary conditions. hence, the major problems of cities inner processes have to be identified and grouped. the european common indicators initiative has two indicators that could have relations with ecology, but this time with “inner” ecology. these indicators are the fifth and eighth: quality of local ambient air and noise pollution. quality of ambient air as well as global warming is determined by particular hazardous pollutants, but in this case the consequences are extremely well visible at a local level, e. g. asthma, decline of working capability, heart diseases, etc. it is investigated that the main pollutants of ambient air in european cities are mainly linked with combustion processes in 1) mobility, 2) heating systems and 3) industries (european commission, 2012). the methodology of the fifth indicator indicates 7 major pollutants, which are following: 1) sulphur dioxide, 2) nitrogen dioxide, 3) carbon monoxide, 4) volatile organic compounds, 5) particulate matter, 6) ozone and 7) lead. noise pollution as well as quality of ambient air is directly related to human health. furthermore, it is a local problem that occurs only in particular places. the eighth indicator describes noise pollution as unwanted or harmful sound created by human activities; sound can be generated from traffic (i. e. road, rail, air) and from sites of industrial activity (european commission, 2012). it is interesting to note that here we see the same mixture of energy and industry activities, the key difference is that here local impact is more severe. 4. results and discussion the results are expressed graphically in fig. 2. an important moment is a direction of arrows: it indicates direction of city’s ecological impact, which can be outer (arrow points up) or inner (arrows point in). capital letters indicate components of city’s ecology: 1) greenhouse gases, 2) quality of ambient air and 3) noise pollution. the main shortcoming of a model is limited “inner” ecology because it basically regards only citizens welfare and ignores the rest, i. e. flora and fauna. however, the principle idea of the model is a critical threshold or limit and thus it allows some losses, but only some. in this particular case “some” means that these losses are not crucial to the specific population and do not cause irreversible changes. therefore, exceeding of the critical level is not allowed. ecology of city: levels and components 35 noise pollution as well as quality of ambient air is directly related to human health. furthermore, it is a local problem that occurs only in particular places. the eighth indicator describes noise pollution as unwanted or harmful sound created by human activities; sound can be generated from traffic (i.e. road, rail, air) and from sites of industrial activity (european commission, 2012). it is interesting to note that here we see the same mixture of energy and industry activities, the key difference is that here local impact is more severe. 4. results and discussion the results are expressed graphically in fig. 2. an important moment is a direction of arrows: it indicates direction of city’s ecological impact, which can be outer (arrow points up) or inner (arrows point in). capital letters indicate components of city’s ecology: 1) greenhouse gases, 2) quality of ambient air and 3) noise pollution. the main shortcoming of a model is limited "inner” ecology because it basically regards only citizens welfare and ignores the rest, i.e. flora and fauna. however, the principle idea of the model is a critical threshold or limit and thus it allows some losses, but only some. in this particular case “some” means that these losses are not crucial to the specific population and do not cause irreversible changes. therefore, exceeding of the critical level is not allowed. fig. 2. ecology of city 5. conclusions although ecology of city is a very common phrase nowadays it yet lacks unification and thus to develop a city’s development plan that would consider ecological aspect is a tricky question. ecological element is one of the sustainability’s compounds but it is in essence different: it has limits while sustainability is a dynamic process. taking into account the major environmental problems and international initiatives it has been proposed to set only two stages of city’s ecology. the results are expressed graphically in fig. 2 and differ according to the impact they have on the surroundings. if the impact is oriented outwards then it is regarded as city’s “outer” ecology otherwise it is “inner” ecology (i.e. it has impact within administrative boundaries). “outer” ecology is concerned with emissions of greenhouse gases, basically, from energy and waste management sectors and “inner” ecology is related with two components: ambient air and noise pollution. the above mentioned levels and components form a framework for city’s ecology according to which ecological assessment so necessary in urban planning should be done. however, this job still requires further elaboration. fig. 2. ecology of city 5. conclusions although ecology of city is a very common phrase nowadays it yet lacks unification and thus to develop a city’s development plan that would consider ecological aspect is a tricky question. ecological element is one of the sustainability’s compounds but it is in essence different: it has limits while sustainability is a dynamic process. taking into account the major environmental problems and international initiatives it has been proposed to set only two stages of city’s ecology. the results are expressed graphically in fig. 2 and differ according to the impact they have on the surroundings. if the impact is oriented outwards then it is regarded as city’s “outer” ecology otherwise it is “inner” ecology (i. e. it has impact within administrative boundaries). “outer” ecology is concerned with emissions 31 of greenhouse gases, basically, from energy and waste management sectors and “inner” ecology is related with two components: ambient air and noise pollution. the above mentioned levels and components form a framework for city’s ecology according to which ecological assessment so necessary in urban planning should be done. however, this job still requires further elaboration. 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breuste, a. k. hahs, eds. ecology of cities and towns: a comparative approach. new york: cambridge university press, 523-529. who. 2012. climate change and human health. availale at: http:// www.who.int/globalchange/environment/en/index.html (accessed 10 may 2012). received 2012 05 30 accepted after revision 2012 09 03 mindaugas staniūnas – assistant at vilnius gediminas technical university, faculty of environmental engineering. main research area: urban planning and ecology. address: vilnius gediminas technical university, faculty of environmental engineering, sauletekio ave. 11, lt-10223 vilnius, lithuania. tel.: +370 5 274 4719 e-mail: mindaugas.staniunas@vgtu.lt 15 journal of sustainable architecture and civil engineering 2021/1/28 political economy of straw houses: traditional and contemporary way of enhancing sustainability of the buildings received 2020/09/29 accepted after revision 2020/12/22 journal of sustainable architecture and civil engineering vol. 1 / no. 28 / 2021 pp. 15-25 doi 10.5755/j01.sace.28.1.27711 political economy of straw houses: traditional and contemporary way of enhancing sustainability of the buildings jsace 1/28 http://dx.doi.org/10.5755/j01.sace.28.1.27711 introduction cities, as production and consumption hubs, cause significant amount of global co2 emissions and energy consumption. climate change challenges world’s welfare due to the global warming. cities’ environmental footprint can be reduced with the help of energy efficient and sustainable built environment which can further contribute to the wellbeing and welfare of the urban population contributing to the solution of the fuel poverty. straw is a traditional and contemporary material having outstanding technical characteristics (e.g. thermal insulation). straw is a traditional material as it has been used in sheltering starting from the ancient times. straw is a contemporary material as it is used even in small buildings with the help of innovations. furthermore, it is a cost effective material from initial investment as well as maintenance and repair aspects. straw houses can reduce energy consumption. this can reduce countries’ trade deficit due to the reduced demand for energy import, contributing to the solution of the fuel poverty. straw is environmental friendly natural material. constructing straw houses is important for sustainable living. giving importance to the straw house construction can help reduction in the co2 emission and in the energy consumption. based on an in-depth literature review, this paper investigates political economy of straw houses and straw houses’ contribution to the sustainability performance of the built environment. this paper introduces to the literature political economy of the straw houses and provides recommendations on how to widespread the use of straw houses. keywords: energy, environment, housing, politics, political economy of straw houses. *corresponding author: egemens@alumni.bilkent.edu.tr egemen sertyesilisik* gozuyilmaz engineering and marine industries ltd., izmir, turkey seyma yilmaz cevher cam, sumer mah. denizli, turkey begum sertyesilisik izmir democracy university, faculty of architecture, department of architecture, izmir, turkey as none of the countries has unlimited financial power, efficient allocation of budget is important to generate welfare and to enable sustainable development. climate change has started to challenge world’s welfare. effective fight against the climate change requires interdisciplinary action due to its consequences. consequences of the climate change have started to become a threat for rights (levy and patz, 2015). wallimann-helmer (2019) has emphasized the importance of the justice in managing climate change. especially, thanks to the kyoto protocol and paris agreement many countries come together to reduce their co2 emissions, and to reduce their environmental footprint. at this stage finding solution to unsustainable urbanization can support fight against climate change. even if cities cover approximately 2% of the land surface of the world, they consume majority of energy and emit 75% of co2 (united nations, 2014; sertyesilisik & sertyesilisik, 2015: journal of sustainable architecture and civil engineering 2021/1/28 16 83). the building sector’s consumption of 40% of main energy usage is a sample for levermore (2008)’s statement who indicates that the built environment consumes big amount of energy and material (levermore, 2008). european union’s targets for 2020, 2030 and 2050 regarding reduction in the greenhouse gas emissions and increase in the energy efficiency (european union website, n.d.) emphasize need for and importance of improving sustainability performance of the built environment. construction of environmental friendly houses like straw houses can reduce environmental harm caused by the construction industry (ci) and the built environment. straw houses can contribute to the protection of the world’s resources and for enhancing sustainability performance of the built environment. furthermore, straw houses can contribute to the circular economy as they enable waste material to be used as an input. political economy of straw/straw houses is related with the political economy of sustainability and sustainable development. the three pillars of sustainability and political economy are interrelated. sustainability is an important topic of the global political economy (the world bank, 1982; loshaj, 2016). global environmental policies’ topic can be covered by the global political economy which “… is the politics of international economic activities” (e.g. trade, international politics on economic integrations, etc.) (goldstein & pevehouse, 2015: 371). political economy is also concerned with the sustainable development as it is related with “… determining what political and/or economic factors … are restricting the courses of action toward sustainable development” (branco, 2008; rogers & boyd, 2008; loshaj, 2016: 5). straw and straw houses can have potential to contribute to the establishment of the sustainable built environment and to the solution of the fuel poverty problem. based on an in depth literature review, this paper investigates the political economy of straw houses and straw houses’ contribution to the sustainability performance of the built environment. traditional and contemporary usage of straw in the built environment although straw has been used in construction since the paleolithic age (langlois, 2017), straw gained its popularity in late 1800s with the invention of baling machines (steen, steen, & bainbridge, 1994). similarly, straw houses have been widespread in nebreska due to the scarcity of other building materials (amazon nails, 2001) and they date back to 1800s as they are durable (nunan, 2010). contribution of the straw bale’s usage as a construction material to the reduction in the housing costs has further resulted in widespread use of the straw houses (king, 2006; offin, 2010). straw houses are cost effective as straw is easy to find and construct (magwood, 2014) straw is a widely available material. for example, in north america, the amount of straw produced annually is enough for residential building construction (garas, allam, & el dessuky, 2009). apart from residential architecture, many churches, schools, and community and youth centers have been constructed by people who will take advantage of the building to be built (magwood, et al., 2005). thanks to the different-sized modular units, the usage of straw bales could reduce buildings’ construction time period, and the construction waste (walker, thomson & maskell, 2016). furthermore, its construction technique is basic and it enables design flexibility (king, 2006). research in the field of different usage of straw further contributes to its widespread [e.g., the ‘modcell®’ (balehaus at bath n.d.; guarneri, 2014: 732; modcell, n.d.]. nowadays, there are ongoing attempts to construct eco-friendly buildings with biodegradable and renewable building materials because of the depletion of the sources and deteriorated world habitat. kołakowski (2005) stated that straw, which is a raw, traditional and grown naturally material, is one of these building materials (jagielak, 2015: 1). amazon nails (2011) indicates that approximately 1000 new structures per year are built in the world. furthermore, prof. rueger prepared a map in 2010 which shows that there are approximately 700 straw bale dwellings in france, 150 in germany, and 104 in austria (atkinson, 2010). straw is used both in traditional and contemporary ways. traditional usage of straw: traditional construction with straw bales can be pointed off under 3 main types: load-bearing systems as in nebraskan style, non-load-bearing systems, and hybrid systems 17 journal of sustainable architecture and civil engineering 2021/1/28 (magwood, mack, & therrien, 2005). load bearing system is the original one which was firstly used by the nebraskan settlers in the usa (jones & breese, 2009). the bales are pinned to foundation and to each other to be able to carry the wooden roof structure (magwood, 2014). walker, et al., (2016) indicated that the original usage way of the straw bale is still an effective way for low-rise buildings. moreover, if straws are baled, massed, elaborated, and plastered with any earthen renders, they could bear residential scaled loads (bendapudi, potnuru, varanasi & saha, 2012). one of the most important advantages is simplicity of its execution. this method is the easiest way for building load bearing structure as the non-professionals can build their small scale building with the help of basic guides (myhrman & macdonald, 1997). another advantage of this method is less usage of wood or steel in the construction (wilson, 1995). the second method is the non-loadbearing system where wood, steel or concrete frameworks carry the roof whereas the bales act as an infill material (jagielak, 2015). in other words, load-bearing mission is transferred to column and beams, thereby, bales turn into just an infill material for the structure. in this method, it is possible to prevent the straw bales from being affected by adverse weather conditions by starting construction from the structural system and roof (walker, et al., 2016). even if the high insulation properties of straw are utilized in this method, this method is less sustainable compared to the first one due to the need for large amount of timber/steel (amazon nails, 2011). in the third method which is the hybrid method, the most suitable features of the previous two methods are used as straw bales act as a bearer with the main structure, and at the same time provide design flexibility (magwood, et al., 2005). apart from these methods, bales can be used as flooring and ceiling material with their high insulation properties (atkinson, 2010). contemporary usage of straw: nowadays, different methods are being researched to use the straw bale more efficiently and to spread the usage area. prefabricated panel systems could be shown as an example of these researches. researchers at the university of bath’s building research establishment (bre) centre for innovative construction materials had developed new ways of using straw bales for construction which is ‘modcell®’(balehaus at bath, n.d.). in this system, which is developed based on the prefabrication method, the straw in the timber frames makes use of the fast and flexible design of modularity (modcell, n.d.). it is seen that straw has expanded its usage area in contemporary architecture with this prefabrication method, which can be used in the construction of many structures which all have different scales and flow schemes such as school buildings (e.g., glenfrome primary school, waterfoot primary school), student centers (e.g., harlow learning center), media centers (e.g., knowle west media centre), residences (e.g., shirehampton eco-homes bristol), co-houses (e.g., lilac affordable co-houses, balehaus at bath), cafes (e.g., holme lacy campus cafe), and visitor centers (e.g., hengistbury head visitor centre) (modcell, n.d.). another example of the new way of the straw bale usage is the panel-cladding used in the résidence jules ferry building with an eight-story in st-dié-des-vosges in france (walker, et al., 2016). considering that the traditional way of the straw bale is mostly used in small-scale buildings, it can be said that with the advancing technology in contemporary architecture, the range of building types and the building scale which are constructed by using straw have been expanded. magwood et al. (2005) stated that commercial buildings could be more suitable for construction with straw bale than residential buildings because they are prefabricated and modular. furthermore, straw houses and straw can support sustainable contemporary life. after excessive natural disasters, scarcities, and global warming issues, people are seeking a new way of life that is healthy, sustainable, and harmless to the nature. straw bale construction is one of the original techniques for creating that kind of living area (guarneri, 2014). strawbale village proposal by one community can be given as an example of this new way of sustainable contemporary life (one community, 2020). one community -which proposes mini-village models with different eco-building methodsbenefits in their second proposed village from the modular and expandable nature of the straw bales for creating a sustainable, accessible, and collective way of living (one community, 2020). journal of sustainable architecture and civil engineering 2021/1/28 18 straw and sustainability straw houses have various benefits. they perform well especially with regard to: sustainability, energy efficiency, embodied energy, water efficiency, embodied water, and embodied carbon. ci is a carbon-emission intensive industry. furthermore, many of the construction products have high amount of embodied carbon. today, in many countries, there is an increasing tendency to reduce the negative impacts of the ci on the environment with the help of sustainable and green construction. straw bale usage in the construction can reduce the greenhouse gas emissions significantly reducing carbon footprint and embodied carbon of the building (jones & breese, 2009). straw is one of the natural building materials which has many different advantageous features in terms of sustainable construction. contrary to the intensive energy consumption, carbon emission and water consumption in the modern building material production process, straw is more environment-friendly (walker, et al., 2016). straw which is a waste material, is a natural and renewable material which reduces the environmental footprint of the building throughout its lifecycle (bendapudi, et al., 2012). furthermore, usage of straw as a building material, instead of burning it, can contribute to the waste recycling in a sustainable way (nunan, 2010). the usage of locally available straw can further reduce embodied carbon, carbon emissions, energy and transportation cost, as well as support the local economy. furthermore, considering the demolition processes of buildings, straw does not cause environmental pollution as it is dissolved in nature easier. energy efficiency and embodied energy: ci is energy intensive. more than 30% of the worldwide energy consumption results from the ci (andrić, et al., 2017). straw has low embodied energy. the choice of straw bale wall with 6:1:1 section of plaster can be a better selection than traditional construction style of wooden frame with brick siding thanks to its six times lower embodied energy (offin, 2010). embodied energy value of the straw bale has various values depending on analysis type with different parameter [e.g. 0,24 mj/kg (north, n.d.; offin, 2010: 35), 0,4 mj/kg (edminster & alcorn, 1995; offin, 2010: 35), 0,0014 mj/kg (bre, 2001; offin, 2010: 35)]. as ci is carbon emission intensive, improvement of the energy efficiency is important and it can be supported by the usage of straw-bale due to its high thermal insulation value (amazon nails, 2001). this can enhance reduction in the heating and cooling loads. reduction in the rural populations’ dependence on the coal can contribute to the sustainable development (bendapudi, et al., 2012). this reduction can take place with the usage of straw as a main building material as it is a local and waste product of harvested grain. houses constructed with straw generally do not require any additional wall insulation as r-value for straw bale walls ranges between r-17 and r-65 (stone, 2003; offin, 2010). for this reason, considering increase in the world population and global warming, the straw bale structure can be adopted as a housing solution which can contribute to the reduction in the usage of fossil fuels (kennedy, smith & wanek, 2015). embodied water: buildings consume important amount of energy and water (during construction, material manufacturing phase) in the production/manufacturing phase as well as in the occupation and maintenance phase. water usage is a significant environmental problem especially in hot and dry climates. all products need water to be produced. as the total water used in whole stages of the production chain means virtual water, the more the material is processed, the more virtual water is consumed. as straw bales do not undergo industrial processing, the virtual water value is less than many other modern construction materials (e.g., steel, concrete). the considerable amount of water usage for straw bale occurs during the growing process of grains. initial investment, operation and maintenance costs: straw houses have relatively low initial investment, operation and maintenance costs. this potential advantage of the straw houses can contribute to the environmental, social and economic sustainability as well as to the affordability of housing (table 1). straw houses can be considered as a solution to the affordable housing scarcity problem. straw houses are cost effective enabling cost savings throughout the building life cycle periods especially in the construction and maintenance period as they can enable reduction in the labor cost due to the easy/simple construction process and as they can enable 19 journal of sustainable architecture and civil engineering 2021/1/28 reduction in the heating and ventilation due to their high heat insulation (garas et al., 2009). simplistic building method of straw can enable unexperienced people to participate in the design and construction processes (jones & breese 2009). the cost of a straw bale building varies by: region, climate, codes and permit requirements; the method of construction as well as the size and design of the building (woolley & kimmins, 2000); the price paid per bale and distance of the place from where the straw is purchased (steen et al., 1994). furthermore, straw houses’ operation period is cost effective due to the energy efficiency and reduced energy cost. for example, in mongolia, straw bale buildings have approximately 80% less energy consumption compared to the conventional buildings (bainbridge, 2004; garas et al., 2009). the heating costs of straw houses can be reduced by 75% annually compared to traditional residential buildings (jones & breese, 2009:14). straw can balance the air conditions inside of the houses which can give an opportunity to reduce maintaining cost of the building (steen et al., 1994). according to a study of the canada mortgage and housing corporation, the usage of heating energy for space in the straw bale houses is at least 20% lower than the modeled traditional houses (technical series 02-115. 2002; garas et al., 2009). life of straw houses can last for hundred years with very low maintenance costs (steen et al., 1994: 38-39). table 1 examples of main characteristics of straw houses which can contribute to the sustainability and affordability of houses its long life duration and low maintenance costs (steen et al., 1994) its contribution to the reduction in the usage of fossil fuels (kennedy, smith & wanek, 2015) high thermal insulation value (amazon nails, 2001; stone, 2003; offin, 2010; garas et al., 2009) low embodied energy (offin, 2010) reduced energy demand (bainbridge, 2004; garas et al., 2009) and reduced heating costs (jones & breese, 2009; technical series 02-115. 2002; garas et al., 2009) low embodied carbon (jones & breese, 2009) its contribution to waste recycling (nunan, 2010) easy and fast construction (jones & breese 2009; nunan, 2010) moisture and fire related concerns are among the main concerns which need to be addressed throughout the entire lifecycle of the straw houses starting from the design phase so that sustainability and affordability of houses can be achieved (magwood, et al., 2005). as the moisture content over the acceptable ratios can cause serious health problems as it can cause moisture and reproduction of mold spores, straw bale designers and researchers need to give a special attention to this issue (king, 1998). the effective solutions to deal with problems related with water and vapor depend on the climate and region of the building (carfrae, 2011). for example, marc rosenbaum suggests that in cold climates, vapor-retardant paint should be used on the interior wall, whereas in hot and humid climates, this paint should be used on the exterior (wilson, 1995). another precaution to prevent moisture is placement of the air barrier between the bottom of the bales and the footing as the bales can be recommended to be raised approximately 20 cm above ground level (steen et al., 1994). furthermore, detailing of windows is essential measure to prevent from moisture leakage (kennedy et al., 2015). despite of the concerns for the moisture, steen et al. (1994) state that there are straw bale buildings which don’t have any problem of deterioration of the bales in washington which receive 75 inches of rain per year from 1970s and 1980s (steen et al., 1994). fire resistance is another important aspect of straw houses. plastered straw bale walls have lower fire risk than traditional timber frame walls (steen et al., 1994). in accordance with the statements of the canada mortgage and housing corporation, it has been proved that straw bales have high fire resistance (steen et al., 1994). fire retardants (e.g. aluminum sulfate) can be applied to the bale to reduce fire journal of sustainable architecture and civil engineering 2021/1/28 20 risk of the building (myhrman & macdonald, 1997). the greatest risk of fire, however, can emerge due to loose straw that can agglomerate on the worksite. as especially in windy conditions, the flames can easily spread through these straws, sweeping loose straw and storing away from building is an important issue (myhrman & macdonald, 1997). political economy of straw houses political economy of straw houses is related with the straw’s performance and effects regarding to the three pillars of sustainability (fig. 1). straw houses can have impacts and contributions to these three pillars of sustainability which can act as drivers for increasing demand for them (fig.1). straw and straw houses can have impact on the environmental sustainability with the help of their low environmental footprint due to their energy efficiency, water efficiency, low embodied energy, carbon and water as well as their contribution to the circular economy. straw can substitute some of the materials having higher embodied energy, carbon, and water as well as reduce their market share. according to peñaloza et al. (2018: 1025), there is a necessity to urgent mitigation measures for ci’s ghg emissions as it causes “19% of the global ghg emissions.” (peñaloza et al., 2018: 1025). as building straw houses can help to protect the environment, they can help governments and ngos to reduce their spending to protect the environment. protecting environment and reducing air pollution can make people healthier reducing their health care spending. straw and straw houses can contribute to the social sustainability due to relatively fast and easy construction process, relatively low construction/initial investment cost, operation and maintenance costs heating and cooling costs (due to relatively low active heating and ventilation requirements). easy construction process can enable creation of job opportunities for relevant workforce or they can enable the potential home owners to build their own houses. fast construction process can enable demand for housing to be fulfilled fast even in the post-emergency or post-disaster phases. using straw is relatively faster option for the construction in terms of both preparation and execution process (e.g. no curing or drying period for the straw; no fabrication process for the straw) (nunan, 2010). easy and fast construction process of straw houses as well as their relatively low initial investment, operation and maintenance cost can enable straw houses to act as affordable housing and post-disaster housing. these potential benefits of straw houses can support welfare and wellbeing of the occupants. straw and straw houses can have impact on the economic sustainability and welfare creation. enhanced circular economy can reduce the demand for and consumption of the raw materials which can be used in other value added production processes and products. furthermore, potential contributions of the straw houses in reducing environmental footprint of the ci can contribute to the wellbeing of the occupants and to reduce health care spending. potential contribution of the straw and straw houses to the reduction in the energy demand (bainbridge, 2004; garas et al., 2009) for construction and operation of the built environment can strengthen countries’ economy through reduced energy deficiency. as ci is responsible for at least 30% of the global energy consumption (andrić et al., 2017), energy efficiency is important to reduce energy trade gap and to enhance sustainable development (berk & cin, 2018). even in developed countries energy trade deficiency plays an important role in the economy. for example, energy caused america’s trade gaps (tsafos, 2018). governments can invest more owing to this kind of energy saving which will enhance welfare of the people. they can allocate their budget more on investment to respond to their societies’ needs. furthermore, people who have reduced their energy spending, can spend more on leisure and on other investments which can make economy vivid and lead to the economic development. these examples reveal that straw houses are among the other factors which can influence the sustainable development. environmental, social, economic, political, legal, technical and innovation aspects can act as constructs of the political economy of straw houses (fig.1). they can act as enablers for wide spread21 journal of sustainable architecture and civil engineering 2021/1/28 ing straw material usage and straw houses’ constructions. these constructs influence each other. among these constructs, political and economic factors can act as key enablers and drivers for straw and straw houses (fig. 1). for example, townsend et al. (2018)’s research on the availability of wheat straw for bioenergy generation in england, revealed the importance of pricing policy and its impact on the motivation of farmers for exploring innovative ways for increasing straw supply. furthermore, policies and economic decisions encouraging research and development activities on innovative ways of using straw can further contribute to the wide spreading of straw material and straw houses. there are various examples for research and developments which can contribute to the innovations having potential to contribute to the widespread usage of straw [e.g. enhancing durability of straw focusing on straw types’ water sorption in wall construction (yin, et al., 2018); usage of different straw types (lavender and barley) as bio aggregates in earth bricks (giroudon et al., 2019); enhancing efficiency in the straw resources’ usage (straw return versus usage of straw briquette fuel as a substitute for rural heating coal) (zhang et al., 2019); investigation of straw’s usage in methane production (guo et al., 2019); optimum straw return-to-field ratio (liu et al., 2019); hygrothermal and funistatic properties of two new straw blocks on the northern wall of a solar greenhouse (ren et al., 2019), etc.]. fig. 1 political economy aspects of the straw houses effective policies, laws, and regulations need to be in integrity and in compliance with the global climate justice and urban climate justice. bulkeley et al. (2013) have emphasized the relationship between climate change politics and justice. furthermore, michalec et al. (2019) introduced smart and just city concept (michalec et al., 2019). based on the undp (2016)’s definition of human development, alves & mariano (2018) have emphasized relationship between climate justice and human development. urban climate justice can influence emergence of new laws which can contribute to the sustainable development and encourage construction of environmental friendly buildings and cities. how to implement these new laws is also part of the political economy. “…the political economy endeavors to connect political and economic procedures within a nation.” (the world bank, 1982; loshaj, 2016: 4). examples for such procedures can include water reforms or ways for implementation of new laws (the world bank, 1982; loshaj, 2016). effectiveness of policies, laws, and regulations is related with their economic impacts which can influence supply of and demand for straw based materials and straw houses. governments can encourage businessmen to build journal of sustainable architecture and civil engineering 2021/1/28 22 straw houses. governments can reduce taxes or give subsidies to the businessmen who want to build straw houses or who want to invest in innovations related with straw materials. furthermore, effectiveness of the policies, laws and regulations depends on the stakeholders’ contribution as well as on the systematic approach. main stakeholders and their main roles in enhancing political economy of the straw and straw houses have been illustrated in the fig. 2. climate change policies (both mitigation and adaptation policies) can be managed in an integrated way with the help of effective urban governance and with the participation of local governments (lee & painter, 2015). furthermore, political feasibility depends on societal transformation and social justice (patterson et al., 2018). effectiveness of the climate policies and their acceptance can be further enhanced in case policy makers consider long-term effects of climate policy (bretschger, 2017). furthermore, academics and researches can collaborate further to enhance effectiveness and widespread usage of straw in the ci through their research and development activities. research funds can encourage their research activities in this field. these funds together with effectively allocated subsidies to the manufacturers can foster widespread usage of this traditional material as a contemporary material in contemporary built environments. architecture and civil engineering undergraduate education curriculums can be effective tools to enhance future construction professionals’ knowledge on and preference of straw materials usage in an innovative and contemporary way. fig. 2 main stakeholders and their main roles in enhancing political economy of the straw and straw houses political economy of straw houses needs to be considered as inputs to the housing policies. sustainability and affordability performance of straw houses highlight their important role in housing policies and sustainable development policies. a – main institutions and their main roles in enhancing political economy of the straw and straw houses; b – main individuals in enhancing political economy of the straw and straw houses. a b 23 journal of sustainable architecture and civil engineering 2021/1/28 conclusions references humanity’s environmental footprint has been asymptotically increased since the first industrial revolution. humans should use the world’s natural resources more efficiently, as failure to do so can obstacle sustainable living on earth. straw, as a traditional and contemporary material, can provide sustainable solutions. straw and straw houses can contribute to dealing with this challenge as they can support and protect nature and natural resources with the help of their low embodied energy, carbon and water. their potential contribution to the three pillars of sustainability and to the sustainable development make them a subject of the political economy. this paper focused on the political economy of straw houses and straw houses’ contribution to the sustainability performance of the built environment. political economy aspects of straw houses were explained under the environmental, social, economic, political, legal, technical and innovation categories which are interrelated. these categories are the main pillars of the political economy of straw houses and their effectiveness and success depends on the successful management of their relationship and their impact to each other as well as on the effective contributions of all stakeholders. further studies can focus on how to widespread straw material usage in developing and underdeveloped countries to fulfill their sustainable development needs. alves, m.w.f.m., mariano, e.b. climate justice and human development: a systematic literature review. journal of cleaner production, 2018; 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(2014). making better buildings: a comparative guide to sustainable construction for homeowners and contractors. canada: new society publishers. retrieved from https://0-ebookcentral-proquest-com. divit.library.itu.edu.tr magwood, c., mack, p., & therrien, t. more straw bale building: a complete guide to designing and building with straw. gabriola island, b.c., canada: new society, 2005. michalec, a.o., hayes, e., longhurst, j. building smart cities, the just way. a critical review of “smart” and “just” initiatives in bristol, uk. sustainable cities and society, 2019; 47: 101510. https://doi.org/10.1016/j.scs.2019.101510 myhrman, m. a., macdonald, s. o. build it with bales: a step-by-step guide to straw-bale construction, tuscon, az: out on bale; 1997. retrieved january 15, 2018, from http://www.dcat.net/about_dcat/images/biwb/ biwb%20v2%20all%20pages.pdf modcell n.d. sustainable pre-fab straw bale panel construction. retrieved january 24, 2018, from http:// www.modcell.com/ nunan, j. complete guide to alternative home building materials & methods including sod, compressed earth, plaster, straw, beer cans, bottles, cordwood, and many other low cost materials. atlantic publishing group, ocala, florida; 2010. offin, m. straw bale construction: assessing and minimizing embodied energy. masters dissertation, environmental studies, queen’s university, kingston, ontario, canada; 2010. one community (march 29, 2020). “straw bale village one community pod 2”. retrieved november 25, 2020, from https://www.onecommunityglobal.org/ straw-bale-village/ patterson, j.j., thaler, t., hoffmann, m., hughes, s., oels, a., chu, e., mert, a., huitema, d., burch, s. & jordan, a. political feasibility of 1.5c societal transformations: the role of social justice. current opinion in environmental sustainability, 2018; 31: 1-9. https:// doi.org/10.1016/j.cosust.2017.11.002 ren, j., zhao, z., zhang, j., wang, j., guo, s., sun, j. study on the hygrothermal properties of a chinese solar greenhouse with a straw block north wall. energy & buildings, 2019; 193, 127-138. https://doi. org/10.1016/j.enbuild.2019.03.040 rogers, p., boyd, j. a. an introduction to sustainable development. publisher: routledge; 2008. peñaloza, d., erlandsson, m., berlin, j., wålinder, m., falk, a. future scenarios for climate mitigation of new construction in sweden: effects of different technological pathways. journal of cleaner production, 2018; 187: 1025-1035. https://doi.org/10.1016/j.jclepro.2018.03.285 sertyesilisik, b., sertyesilisik, e. sustainability leaders for sustainable cities, in: leadership and sustainability in the built environment. routhledge taylor & francis group new york; 2015. 25 journal of sustainable architecture and civil engineering 2021/1/28 about the author steen, a. s., steen, b., bainbridge, d. a. the straw bale house. white river junction, vermont: chelsea green publishing; 1994. stone, n. thermal performance of straw bale wall systems, ecological building network (ebnet); 2003. retrieved from http://www.ecobuildnetwork.org/pdfs/ thermal_properties.pdf technical series 02-115. energy use in straw bale houses. canada mortgage and housing corporation; 2002. http://buildingsgroup.nrcan.gc.ca the world bank. world development report 1982: agriculture and economic development. new york: oxford university press; 1982. townsend, t.j., sparkes, d.l., ramsden, s.j., glithero, n.j., wilso p. wheat straw availability for bioenergy in england. energy policy, 2018; 122: 349-357. https:// doi.org/10.1016/j.enpol.2018.07.053 tsafos, n. can energy close america’s trade deficit?, the center for strategic and international studies, july 10, 2018 http://www.csis.org/analysis/can-energy-close-americas-trade-deficit un. the future we want: sustainable cities; 2014. http:// www.un.org/en/sustainablefuture/cities.shtml#facts walker, p., thomson, a., & maskell, d. straw bale construction. in nonconventional and vernacular construction materials. cambridge, usa: elsevier science & technology, 2016: 127-155. https://doi.org/10.1016/ c2014-0-00842-8 wallimann-helmer, i. justice in managing global climate change. in: letcher, t. (ed.) managing global warming: an interface of technology and human issues. london cambridge, academic press, 751-768; 2019. https:// doi.org/10.1016/b978-0-12-814104-5.00026-0 wilson, a. straw: the next great building material? environmental building news 4, no.3 (may-june): 1, 11-16; 1995. retrieved january 23, 2018, from https://www.buildinggreen.com/feature/straw-next-great-building-material woolley, t. m., & kimmins, s. “green building handbook: volume 2: a guide to building products and their impact on the environment” (vol. 2). london. e & fn spon: taylor & francis group, 2000. yin, x., lawrence, m., maskell, d., ansell, m. comparative micro-structure and sorption isotherms of rice straw and wheat straw. energy & buildings, 2018; 173: 11-18. https://doi.org/10.1016/j.enbuild.2018.04.033 zhang, s., deng, m., shan, m., zhou, c., liu, w., xu, x., yang, x. energy and environmental impact assessment of straw return and substitution of straw briquettes for heating coal in rural china. energy policy, 2019; 128: 654-664. https://doi.org/10.1016/j.enpol.2019.01.038 egemen sertyesilisik position at the organization freelance consultant in gozuyilmaz engineering and marine industries ltd. main research area sustainability, sustainability policies, political economy address gozuyilmaz engineering and marine industries ltd., izmir, turkey e-mail: egemens@alumni.bilkent.edu.tr this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/ ). şeyma yilmaz position at the organization msc architect in cevher cam main research area sustainability, construction project management address cevher cam, sumer mah. denizli, turkey e-mail: seyma.ylmaz.93@gmail.com begum sertyesilisik position at the organization professor, izmir democracy university, faculty of architecture, department of architecture main research area sustainability, construction project management address izmir democracy university, faculty of architecture, department of architecture, izmir, turkey e-mail: begum_sertyesilisik@hotmail.com 12 darnioji architektūra ir statyba 2014. no. 1(6) journal of sustainable architecture and civil engineering issn 2029–9990 design and analysis of technical fabric confined sand wall under dynamical impact load lazazi menaa1*, ali bouafia2, a/k cherifi3 1 department of civil engineering, university of medea, algeria. 2 department of civil engineering, university of blida, algeria. 3* department of mechanical engineering, usthb university, algeria. * corresponding author: lazazimenaa@yahoo.fr http://dx.doi.org/10.5755/j01.sace.6.1.4691 confining granular materials still a very benefic practice to achieve civil different engineering works. in this paper, the design and analysis of a wall shaped structure made of technical fabric-confined sand will be exposed. this composite structure, made of local materials, where, polyvinyl chloride (pvc) technical fabric constitutes a containing envelope and sand a filler material. designed wall represents a good sustainable development project (idea) to build single story buildings in hot and humid inaccessible areas (sahara); alternatively, it may provide many other geotechnical applications as retaining walls etc. an experimental campaign to identify the mechanical and physical properties of the studied structure was conducted. earlier, and not exposed here, a design and analysis of a 1/5 scale model is achieved to evaluate a bearing ability of the wall under vertical compressive and horizontal flexural loads is done. test to evaluate energy dissipative power of the wall under impact has been also conducted and discussed. keywords: bearing wall, dynamic load, impact load, technical textile, confined sand, protection structure. 1. introduction idea of soil confining, applied in civil engineering (geotechnics), is relatively older: we can refer to classical used in practice gabion retaining walls, where the material (stone) is confined within steel net. geobag structures (geoconteners), using the same practice, developed a few years ago, had allowed the conception of many geotechnical and civil engineering works (xu, and huang 2009). mariotti and millot (1986) have made banquettes with confined sand, using geotextile bags to reinforce the subgrade of ballast rails in morocco. geoconteners, according french standards and definitions of the company “international geosynthetic society”, can describe all alveolar structures obtained by alternative connection of flexible or rigid textile bands. in this context, reiffsteck (1998) had developed an experimental model analyzing a three-dimensional honeycomb structure made of geotextile for use in slope stabilization. panoply of studies have identified the most influential parameters on the behavior of the designed structural cell, it is mainly geometrical and mechanical parameters (shimizu and inui 1990; rajagopal, krishnaswany and madhavi, 1999). this confirms previously published work results, showing that the confinement leads to an improvement of the strength for materials with lower cohesion. the unreinforced and reinforced materials show the same angle of internal friction, while the latter have a high apparent cohesion due to the confinement. as example, reiffsteck (1996) find out that apparent cohesion for composites made with two different aggregates varies from 156 to 190 kpa. a technical fabric was used for the first time in confining to make out an envelope within which sand is carefully compacted to obtain a composite vertical wall. filler works under both shear and compression, while the fabric works in tension (vacilkov and simvulidi, 1985). thanks to the confinement effect and compatibility of deformations and symbiosis collaboration between the fabric and the sand, the structure could assume a sufficient bearing capacity once subjected to vertical or / and horizontal loads, while the qualities of shear and / or damping are desired. analysis of the dissipative power is conducted basing on founded works in the literature. we can cite the work where long geotextile bags with confined sand, were used to constitute an energy dissipative structure by mobilizing elasto-plastic deformation (mougin, perrotin, mommesim, tonnelo, and agbossou 2005). besides, a known “pneusolstructure” conception, with qualities of energy absorbing is considered as cheaper alternative (esbeling, nguyen, modercin, ursat, 1994) compared with classical protective dikes (nicot, gotteland, bertrand and lambert, 2007). 13 the objective of this work is to conduct an experimental campaign devoted to the evaluation of all aspects of the mechanical and physical behavior of the studied wall 2. architectural and structural design the designed wall made of local materials, is characterized by its light weight, easiness of its transportation, installation and implementation. the studied wall should be used as a bearing structural element, to implement a circular in plan single story temporary building (figs. 1a and 1b), which may be located in difficulty accessible areas (sahara) (menaa, 1990). the trapezoidal cross section of the wall, with desired thickness and height involves its good acoustic and thermal insulation, especially in hot and humid areas (fig. 2). for its efficiency working, it is recommended to protect the technical fabric with special revetment in order avoiding vandalism acts since fabric is conceived to resist to ultraviolet rays. another alternative of use of designed wall is antiimpact protection structure. the analyzed composite wall could marry constructions (as petrochemical storage tanks), to receive and absorb potential impact loads. the study focuses on the analysis of composite wall, vertically sited and associated to a lightly reinforced concrete facing to endure and dissipate impact energy, in practice until 1000 kj (figs. 3a and 3b). habitation area fig. 1a. circular in plan mono-story habitation building wall with confined sand fig. 1b. vertical cross of habitation building 1 2 fig. 2. vertical cross section of the wall. legend: 1 – fabric envelope; 2 – filler sand protected tank fig. 3a. impact protective structure protective wall with cofined sand protected tank fig. 3b. vertical cross of protective structure 3. experimental study 2.1. characterization of the constituent materials the technical fabric consists of a polyester reinforcing fabric (support), coated with four layers of polyvinyl chloride (pvc); it has been tested under axial tension using standardized fabric bands (astm d1682); results are comparable to those find in the literature (andrewers 1984). the filler material (sand) is characterized through its water content, density, and particle size distribution. according to the lcpc classification, used sand is close to the coarse one. results of this characterization are earlier presented (menaa, benouali and bouafia2007). 2.2. confinement effect vulgarization 2.2.1. testing method the parameters governing the shear behavior of sands were evaluated by triaxial compression test, using specimens (17.5 cm x 7 cm) and shear casagrande box, using specimens (2.07 cm x 6 cm) to test direct shear box were performed. these tests under a confining pressure of 0.3 mpa were conducted to peak characteristics given in table 1. table 1. results of the shear test type of sand c’ (kpa) j’ (°) direct shear triaxial test coarse sand 0 41.74 confined coarse sand 160 63.66 54.39 14 fig. 4. deviatoric stress-strain curve 2.2.2. results and discussion effect of confinement is highlighted throughout improvement of the intrinsic characteristics of tested material. results show significant differences between the confined sand and sand alone (figs. 4, 5, 6); pure sand presents zero cohesion while the confined one presents about 160 kpa cohesion. moreover, friction angle increases with about 12.70°, witch represents an improvement about of 30 %. furthermore, deformability at failure of confined sand is twice greater than of pure sand. this deformability seems to be related to a mobilized friction within the sand particles. besides, it can be noted that, the values of the angle of dilation about of 12.80° and a poisson’s ratio about of 0.30. fig. 5. volumic deformation curve fig. 6. intrinsic curve 2.3. study of mechanical behavior keys parameters of the wall 2.3.1. behavior under compression the compression test was conducted on 20 cm cubic specimens (fig. 7a) using a press of 20 kn range. the results of the compression test are shown in figure 8. 2.3.2. bending behavior a three point bending test was conducted on prismatic specimens (20 x 20 x 60) cm3 (fig. 7b) on the same press previously used. results are shown in figure 9. a) b) fig. 7. photos of tested specimens:a) cubic specimen (20x20x20) cm3; b) prismatic specimen (20x20x60) cm3 2.3.3. shear behavior the shear test was also conducted on cubic specimens (20 x 20 x 20) cm3 (fig. 7 a) using a specially designed testing stand. all results are shown in figure 10. fig. 8. stress-strain compression curve fig. 9. stress-strain bending curve fig. 10. stress strain shear curve 2.3.4. effect of sand type the effect of the quality of used sand on the specimen’s deformation is clearly observed. deformations are larger with fine sand (sand dunes) than coarse sand (concrete 15 sand), while, well graded sand deforms faster and set off to a stationary elastic state (fig. 11). failure takes place close to line of stitching for strength of 14.6 kn. these results, valid in both compression and shear, seem correlated with those obtained by other studies using geotextiles as an alternative of our technical material. fig. 11. effect of type of sand 2.3.5. influence of fabric assemblage in this test, the compression strength of cubic confined sand specimens is recorded for different types of assemblage: by sewing and thermo-welding. in the first case, the failure occurs at the line of stitching for a force value about of 15 kn; for the second case, we observe a higher tensile strength (about 75 kn), which corresponds to approximately five times the first value. it can be concluded that the thermo-welded linkage leads to a more efficient assemblage (fig. 12). fig. 12. effect of assemblage type 2.3.6. effect of loading surface study of the relationship between the charged surface and the volume of confined sand is evaluated by compression tests at constant deformation. accordingly, cubic specimens were tested considering two different loading surfaces: loading surfaces of (10 x 10) cm ² and (20 x 20) cm². the results are shown in figure 13. the shapes of the stress – strain curves show the same tendency in both cases of loading area. for the same volume of confined sand and a given stress level, mobilized deformations are rapidly reached when the load area is important; it can be concluded that, the confining fabric enclosure probably tends more rapidly to elastic behavior. fig. 13. effect of loading surface 2.3.7. effect of loading cycle in order to evaluate the behavior of confined models after plastic deformation mobilization, compression tests under repeated cyclic load of 100 kn, on cubic fabricconfined sand specimens were carried out. the testing results are shown in figure 14; a stiffening of the specimen is observed for a more high loading cycle. fig. 14. loading cycles curves 2.4. scaled model testing 2.4.1. study of a wall bearing capacity analyzed wall can work in two positions (vertical or horizontal) and under any loading case; three testing cases of a 1/5 scaled model were carried out: first, under lateral loading with a vertical position, then, the vertical wall is loaded simultaneously (vertical and lateral loads); finally, the wall horizontally located, is subjected to a vertical compression loading. in this paper, only results of the first case are presented. the laterally loading test shows a good bearing capacity of the wall, while remaining within the elastic stress diapason (menaa, amar bouzid and benouali, 2009). the same model is used later to analyze the dissipative power of studied wall (fig. 15a and b). 16 a) b) fig. 15. testing cases of scaled model 2.4.2. study of a wall dissipative power scaled models of varying thickness sizes (e) and diaphragm spacing (s) (fig. 16) are tested under the same conditions to measure the impact force and then estimate the rate or dissipation index (ad). this index is defined as the ratio between the static weight of the launched ball (m) and the measured dynamic force (d) respectively. this study leads to evaluate the optimal variant of the wall to perform an optimal protection against impacts. d m ad = (1) 2.4.2.1. experimenting stand design the experimental device consists of a suspended pendulum with a fixed steel ball at its lower end. a sensor, fixed to the support frame, for measuring the impact force is located behind a tested wall (fig. 17). the various cases are obtained by combinations of different thicknesses (e = 10, 20, 30) cm, and different spacing (s = 10, 20, and 30) cm, with or without concrete facing: 1 – virgin sand 2 composite fabric-confined sand wall, and 3 – the same composite wall associated with a concrete facing. launching intensity is about 1000 j. fig. 16. horizontal cross section of wall fig. 17. impact testing device table 2. ad results for different combinations of (e) and (s) e (cm) 10 20 30 s (cm) 30 20 10 30 20 10 30 20 10 ad (%) 20,1 30,2 35,1 36,2 40,1 46,1 45,2 50,1 55,3 2.4.2.2. results the impact forces transmitted through the composite structure were measured and compared; the objective is to determine the values of dissipation for the different cases of composite walls (table 2; fig. 18). the model made with a thickness e = 20 cm and spacing s = 20 cm gives an index of dissipation close to 40.1 %. this value is in the neighborhood of to the median test results; hence, this case can be considered, as early, as an ideal model to design dissipative and protection structures against impact. figure 19 shows optimization of wall models using (ad – s) and (ad – e) relations. fig. 18. histogram of 03 testing cases fig. 19. geometrical optimization of the model 4. general conclusion and perspectives experimental campaign achieved on cubic and prismatic specimens can lead to determine, through appropriate calculus, the equivalent mechanical characteristics of the wall, in particular, the modulus of longitudinal compression (e), the bending stiffness modulus (ef) and the shear modulus (g). 17 for small deformations, the initial modulus of elasticity is in the order of 10.50 mpa; the value of the secant modulus increases to the value of 74 mpa, approximately seven times the value of the initial modulus. furthermore, results of tested reduced model show a good bearing capacity of the wall, while remaining within the elastic range. the analysis of the capacity of energy dissipation of the studied structure leads to discuss an alternative application as protection against shock impacts. as perspectives, a numerical analysis of the wall using a 3d finite elements simulation code can be initiated in the future to validate the experimental results and define the behavior of more or less complex studied structure. acknowledgement we thank professor b. s. vacilkov for his valuable advices and guidance. we also thank the director of the laboratory of materials and structures ‘cnerib’ and technicians for their assistance and cooperation to carry out the necessary tests related to the present study. references andrewers, k. uniaxial strength testing of woven and nonwoven geotextiles. journal of geotextiles and geomembrane, 1(1), (1984), pp 41–55. http://dx.doi.org/10.1016/0266-1144(84)90004-9 astm d1682. standard test method for tensile strength of geotextiles, geomembranes and related products. esbeling, g., nguyen t. l., modercin i., ursat p. pneusol at the bussang pass. third international conference on case histories in geotechnical engineering, st louis missouri, june 1993, (1994). mariotti, m., millot, m. développement de l’utilisation de géotextiles performants dans la stabilité des voies ferrées au maroc. service voies et ouvrages d’art. rapp. oncf – maroc 86-01, (1986). menaa, l. a pvc textile-sand wall analysis under lateral load (in russin). thèse de doctorat, département de structures, institut de génie civil de moscou, (1990). menaa, l., benouali, a/h, bouafia, a. caractérisation mécanique de modèles cubiques en sable confiné. 14ème conférence régionale africaine de mécanique des sols et de géotechnique, yaoundé, cameroun, (2007), pp. 373–378. menaa l., amar bouzid dj. and. benouali a. h. experimental and numerical analysis of a pvc textile-confined sand structure. contemporary engineering sciences, vol. 2, no. 4, (2009), pp 179–190. mougin, j. p., perrotin, p., mommesim, m., tonnelo, j., agbossou a. rock fall impact on reinforced concrete slab : an experimental approach. international journal of impact engineering. 31(1), (2005), pp 169–183. http://dx.doi.org/10.1016/j.ijimpeng.2003.11.005 nicot, f., gotteland, p., bertrand, d., and lambert, s. multi-scale approach to geocomposite cellular structures subjected to impact. international journal for numerical and analytical methods in geomechanics, 31(1), (2007), pp 1477–1515. http://dx.doi.org/10.1002/nag.604 rajagopal k., krishnaswany n. r., madhavi latha g. behaviour of sand confined with single and multiple geocells. geotextiles and geomembranes, 17(1), (1999), pp 171–184. http://dx.doi.org/10.1016/s0266-1144(98)00034-x reiffsteck, p. expérimentation et modélisation de structures en sol renforcé par un géotextile tridimensionnel alvéolaire. revue française de géotechnique, 82(1), (1998), pp 55–65. reiffsteck, p. etude du comportement mécanique du géotextile tridimensionnel alvéolaire armater. analyse numérique et expérimentale. thèse de doctorat, université blaise pascal, (1996). shimizu, m., inui, t. increase in the bearing capacity of ground with geotextile wall. iv congrés international des géotextiles, vol 1, (1990), p. 254. vacilkov b. s., simvulidi t. design and study of technical pvc textile-ground walls. moscow (in russian), (1985). xu, y. f., huang, j. case study on earth reinforcement using soil bags. geosynthetics in civil and environmental engineering, 8(1), (2009), pp 597–602. http://dx.doi.org/10.1007/978-3-540-69313-0_111 received 2013 06 26 accepted after revision 2013 09 25 lazazi menaa – department of civil engineering, university of medea, algeria. main research area: civil engineering; geotechnics and materials. address: bp 120university of medeamedea, 26000algérie. tel.: +213 772 26 40 90 e-mail: lazazi.menaa@yahoo.fr ali bouafia – department of civil engineering, university of blida, algeria. main research area: soil mechanics; geotechnics. address: university of blidablida 9000algérie. tel.: +213 771759496 e-mail: bouafia1@yahoo.fr m/karib cherifi – department of mechanical engineering, university of bab ezzouar, algeria. main research area: soil mechanics; geomecanics; materials. address: university of babezzouaralger 16000algérie. tel.: +213 21503510 e-mail: acherifi_consult@yahoo.fr 35 darnioji architektūra ir statyba 2013. no. 1(2) journal of sustainable architecture and civil engineering issn 2029–9990 investigation of physical and chemical properties of low-temperature hydraulic binder from latvia’s raw materials inta barbane*, inta vitina, lauma lindina, linda krage riga technical university, institute of silicate materials, azenes street 14/24, lv-1048, riga, latvia * corresponding author: inta.barbane@rtu.lv http://dx.doi.org/10.5755/j01.sace.1.2.2838 a necessity of compatible material to historical romancement for restoration needs has led to research of artificially made binders from mixtures of clay and dolomite. low temperature hydraulic binder or so called dolomitic romancement synthesis of mixture composed from local quaternary period clay and dolomite (both in powder state) in mass ratio 24:76 is discussed in this paper. the chemical composition of the raw materials was analyzed. specimens were prepared by homogenizing the mixture of requisite amounts of clay and dolomite in dry state and shaping samples measuring 56x26x6 mm by semidry pressing. after firing at temperatures between 650 and 1050°c crystalline phases formed in samples were determined by xrd. afterwards, water was added to the samples and formation of new crystalline phases was detected in the period of 28 days. natural dolomitic marl was treated at the same conditions in order to compare the crystalline phases formed in naturally and artificially made binders. the results of xrd analysis show that crystalline phases of synthesized composition after firing are equal to crystalline phases in dolomitic marl fired at the same temperature. the main crystalline phases are quartz (sio2), calcium oxide (cao), dicalcium silicate (2cao•sio2), tricalcium aluminate (3cao•al2o3), gehlenite (2cao•al2o3•sio2) and magnesium oxide (mgo). chemical and mineralogical composition that is close to historical material is one of the main requirements for restoration materials as they provide compatibility. keywords: clay, compatibility, crystalline phases, dolomite, low-temperature binder. 1. introduction one of historically widely used low-temperature binders has been romancement – i.e. natural cement, produced from clay containing carbonatic rocks. during 19th/20th century it was the main hydraulic binder applied for the construction of buildings. (varas et al. 2005) historical romancement was a natural hydraulic binder produced by firing marl (mineral composed from 60–75 % calcite or dolomite and 25–40 % clay) below its’ sintering temperature (800–1200°c) and grinding. this type of binder firstly was patented by james parker in 1796. romancement distinguished itself from other hydraulic binders by short setting time (usually 7–20 min), warm brown color and good durability. (kozlowski et al. 2004) in latvia, in contrast to other parts of europe, dolomitic romancement was used. however since the middle of 20th century its production has been stopped. (grosvalds et al. 1997) at the same time, there is a great necessity for compatible materials for restoration purposes. thus the aim of given research was to synthesize a hydraulic binder with chemical and mineralogical composition close to historical dolomitic romancement. 2. methods 2.1. raw materials in order to obtain a mixture with chemical composition identical to historical dolomitic romancement from quaternary period clay and dolomite full chemical analysis of raw materials was carried out. in addition, local dolomitic marl (dzukste deposit, latvia) – raw material of natural dolomitic romancement – was also analyzed. the results of chemical analysis are shown in table 1. content of carbonates (caco3 + caco3∙mgco3) in clay reaches 23 %. it is calculated according to loss of ignition (loi) at 1000 °c, which corresponds to co2 that is released from carbonates. xrd diffraction analysis (fig. 1) approves that clay from deposit spartaks is typical carbonate clay. dominant clay mineral is illite. kaolinite, microcline, plagioclase and quartz are also detected. dolomite from deposit kranciems contains 88 % carbonates (mostly dolomite) and 12 % impurities as quartz and clay minerals (fig. 2). cao/mgo ratio is 1.56. the cao/ mgo mass ratio of pure dolomite is 1,39. (kurss et al. 1997) 36 fig. 1. xrd of clay from spartaks deposit, latvia fig. 2. xrd of dolomite from kranciems deposit, latvia chemical analysis (table 1) shows that carbonate (caco3 + caco3∙mgco3) content in dolomitic marl from deposit dzukste is 80 % and the rest 20 % are clay minerals and quartz. it is approved by xrd analysis (fig. 3): dolomite, illite and quartz are the only crystalline phases detected in marl before firing. fig. 3. xrd of dolomitic marl from dzukste deposit, latvia 2.2. experimental procedure in order to synthesize artificial dolomitic fastsetting cement, local raw materials – quaternary period clay (spartaks deposit, latvia) and dolomite (kranciems deposit, latvia) in mass ratio 24:76 were used. the choice of mass ratio is based to chemical composition of dolomitic marl from which historically dolomitic romancement was produced. both the chemical and crystalline composition of the raw materials were analyzed. specimens were prepared by weighing the requisite amounts of raw materials – clay and dolomite – and homogenizing the mixture in dry state. plate samples were shaped under the pressure of 20 mpa (by adding 10 % water), dried and fired in the temperature range of 650–1050 ºc in 50 ºc steps with the holding time at each temperature for 2 hours. after firing water was added to samples for hydraulic hardening. natural dolomitic marl was parallely treated at the same conditions. development of phases in obtained material depending on production temperature has been investigated immediately after firing and after hydraulic hardening for 3, 7 and 28 days. chemical and crystalline composition has been compared in fired natural dolomitic marl and synthesized mixture. table 1. chemical composition of raw materials for low temperature fast-setting cement, mass % sample component dolomitic marl (dzukste deposit) quaternary period clay (spartaks deposit) dolomite (kranciems deposit) error ± absolute % loss of ignition at 400 ºc 0.64 1.70 0.60 0.3 loss of ignition at 1000 ºc 37.87 11.62 38.87 0.3 sio2 13.26 49.52 8.47 0.5 cao 25.87 9.04 27.88 0.5 mgo 16.15 3.48 17.83 0.5 al2o3 4.77 14.84 4.92 0.5 fe2o3 0.85 5.07 0.58 0.1 na2o 0.03 0.50 0.11 0.01 k2o 0.10 3.39 0.21 0.01 cao/mgo 1.60 – 1.56 – 37 2.3. analytical techniques in order to detect chemical and mineralogical composition both of raw materials as well as the synthesized compositions, the following methods were used: 1) full chemical analysis (carried out according to en 196-2 and a laboratory manual for architectural conservators (teutonico, j. m., 1988)); 2) xrd (rigaku ultima + with cukα. radiation at scanning interval 0–60° (2θ) and speed 2°/min); 3) dta/tg (setaram setsys evolution – 1750). 3. results dta analysis of synthesized composition (fig. 4) shows two endothermic effects in temperature interval 124–227 °c which corresponds to release of adsorbed and chemically bounded water from clay minerals. two sharp endothermic effects at temperatures 777 °c and 853 °c represents dissociation of dolomite and calcite respectively. (svinka et al. 2011) total mass loss reaches 32.6 %. fig. 4. dta and tg of synthesized mixture before firing the results of xrd analysis show that crystalline phases of synthesized composition after firing are equal to crystalline phases in dolomitic marl fired at the same temperature (fig. 5). the main crystalline phases are quartz (sio2), calcium oxide (cao), dicalcium silicate (2cao∙sio2), tricalcium aluminate (3cao∙al2o3), gehlenite (2cao∙al2o3∙sio2) and magnesium oxide (mgo). some portlandite (ca(oh)2) is detected because of rapid reaction between cao and water in moist environment. fig. 5. xrd of natural dolomitic marl and synthesized composition after firing at 900 °c temperature difference is notable in free cao content – there is more of it in synthesized composition than in marl after firing. the relative changes of the amount of crystalline phases were observed by measurement of the characteristic peaks of each phase at equal conditions. formation of two main cement minerals depending on firing temperature is shown in fig. 6 and fig. 7. the tendency is similar for both – synthesized composition and natural dolomitic marl. crystallization of dicalcium silicate (2cao∙sio2) and tricalcium aluminate (3cao∙al2o3) begins at 800 °c temperature and increases at higher temperatures. dicalcium silicate crystallization reaches maximum at 950°c. fig. 6. the changes of amount of dicalcium silicate crystalline phase depending on the firing temperature fig. 7. the changes of amount of tricalcium aluminate crystalline phase depending on the firing temperature crystalline phases after hydration are the same in both – fired marl and synthesized material. they are following: calcite (caco3), quartz (sio2), periclase (mgo), portlandite (ca(oh)2), gehlenite (2cao∙al2o3∙sio2), brucite (mg(oh)2), dicalcium silicate (2cao∙sio2) and calcium aluminate hydrates (mostly 4cao∙al2o3∙13h2o) (fig. 8). when water is added to the mixture, rapid formation of calcium aluminate hydrates occurs. hydration is completed in few hours. the calcium aluminate hydrates mainly are detected to be 4cao∙al2o3∙13h2o. in the specimens fired above 800 ºc after 28 days of hydration xrd analysis shows that more 4cao∙al2o3∙13h2o is formed in samples fired at higher temperatures (beginning with 900 ºc). rapid formation of this phase provides quick setting. 38 hydration of dicalcium silicate is slow. even after 28 days of hydraulic hardening there still is significant amount of unhydrated mineral in the specimens. fig. 8. xrd of synthesized mixture after firing at 900 °c temperature and hydraulic hardening for 3, 7 and 28 days the chemical as well as mineralogical composition of synthesized binder closely conforms with marl’s composition (table 2). table 2. comparison of chemical composition of synthesized binder and dolomitic marl, mass % sample component synthesized composition dolomitic marl (deposit dzukste) error ± absolute % sio2 28.07 21.56 0.3 cao 40.15 42.07 0.5 mgo 24.80 26.26 0.5 al2o3 5.06 7.76 0.5 fe2o3 1.04 1.38 0.1 na2o 0.04 0.05 0.01 k2o 0.32 0.16 0.05 4. discussion the formation of cement minerals is possible just after the dissociation of dolomite, when free cao is released. accordingly to data obtained by dta analysis, it occurs at 777 °c temperature. this is approved by xrd analysis, which detects 2cao∙sio2 and 3cao∙al2o3 crystalline phases present already at temperatures above 800 °c. hydraulic hardening could not be achieved without formation of cement minerals. tricalcium aluminate provides quick setting (characteristic to romancement), but dicalcium silicate – gradual growth of strength which is important for longevity of mortar. the results of xrd analysis approve that these minerals have been formed in synthesized compositions after firing at temperatures higher than 800°c. it is complicated to detect cement minerals’ hydration products by xrd analysis, because calcium aluminate hydrates form fine crystals or stay at amorphous state, but all dicalcium silicate hydration products are gel-like with indefinite structure. (hughes et al. 2009) the main difference between synthesized binder and burned natural dolomitic marl is in the content of free lime – it is higher in synthesized composition and could be caused by lower compactness of grains during firing process. temperatures above 900 °c are inappropriate in order to obtain hydraulic binder from dolomite and clay, due to the formation of inactive mgo (periclase) which hydrates slowly and may cause damage after application of it in mortar. in addition, crystallization of gehlenite (mineral without hydraulic activity) occurs starting with 850 °c temperature and higher. this phase also is undesirable if a binder with high hydraulicity is required. 5. conclusions crystalline phases of artificially synthesized composition (24 % clay and 76 % dolomite) after firing are equal to crystalline phases in dolomitic marl fired at the same temperatures. they are quartz (sio2), calcium oxide (cao), dicalcium silicate (2cao∙sio2), tricalcium aluminate (3cao∙al2o3), gehlenite (2cao∙al2o3∙sio2) and magnesium oxide (mgo). chemical and mineralogical composition of mixture closely conforms with natural marl’s composition. difference is notable in free cao content – there is more of it in synthesized composition than in marl after firing. crystallization of dicalcium silicate (2cao∙sio2) and tricalcium aluminate (3cao∙al2o3) in both – synthesized composition and natural dolomitic marl – begins at 800 °c temperature and increases at higher temperatures. dicalcium silicate crystallization reaches maximum at 950 °c. crystalline phases after hydration are calcite (caco3), quartz (sio2), periclase (mgo), portlandite (ca(oh)2), gehlenite (2cao∙al2o3∙sio2), brucite (mg(oh)2), dicalcium silicate (2cao∙sio2) and calcium aluminate hydrates (mostly 4cao∙al2o3∙13h2o). the calcium aluminate hydrates mainly are detected to be 4cao∙al2o3∙13h2o. in the specimens fired above 800 ºc after 28 days of hydration xrd analysis shows that more 4cao∙al2o3∙13h2o is formed in samples fired at higher temperatures (beginning with 900 ºc). the hydration of dicalcium silicate occurs relatively slow. after 28 days considerable amount of this mineral has remained. temperature of 800–850 °c has been chosen as optimal for production of hydraulic binder from mixture of clay and dolomite similar to natural dolomitic romancement. acknowledgement the research work was carried out in the frame of erdf project „elaboration of innovative low temperature composite materials from local mineral raw materials” (no 2010/0244/2dp/2.1.1.1.0/10/apia/viaa/152). references grosvalds i., lagzdina s., sedmalis u. 1997. dolomitic romancement – low temperature hydraulic binder. in: abstracts of 10th international congress on the chemistry of cement, gothenburg, sweden, 1997, vol. 2, 52–55. hughes d. c., jaglin, d., kozłowski r., mucha d. 2009. roman cements – belite cements calcined at low temperature. cement. concr. res., 39 (2), 77–89. http://dx.doi.org/10.1016/j.cemconres.2008.11.010 39 kozlowski r., adamski g., mucha d. 2004. roman cements – key materials in effectively restoring the built heritage of the 19th century/early 20th century. in: scientific journal of riga technical university, material science and applied chemistry, riga, latvia, 2004, vol. 8, 102–109. kurss v., stinkule a. 1997. latvijas derīgie izrakteņi [mineral resources of latvia]. riga, lu, 122. lvs en 196-2:2005. test methods of cement. svinka v., bidermanis l., svinka r., lindina l., cimmers a., timma i. 2011. termoķīmiskas reakcijas mālu minerālos šūnu keramikas iegūšanai [thermochemical reactions of clay minerals for production of honeycomb ceramics]. in: scientific journal of riga technical university, material science and applied chemistry, riga, latvia, 2011. vol. 24, 56–60. teutonico j.m. 1988. a laboratory manual for architectural conservators. iccrom, rome, 35–52. varas m., alvarezdebuergo, m., fort, r. 2005. natural cement as the precursor of portland cement: methodology for its identification. cement. concr. res., 35 (11), 2055–2065. http://dx.doi.org/10.1016/j.cemconres.2004.10.045 received 2012 11 29 accepted after revision 2013 02 19 inta barbane – b.sc.ing., m.sc.student, science assistant at riga technical university (rtu), faculty of material science and applied chemistry, institute of silicate materials. main research area: chemical analyses of historic mortars, restoration of stone materials, synthesis of new binders for restoration needs. address: riga technical university, institute of silicate materials, azenes street 14/24, lv-1048, riga, latvia. tel.: +371 670 89140 e-mail: inta.barbane@rtu .lv inta vitina – dr.sc.ing., leading researcher at riga technical university (rtu), faculty of material science and applied chemistry, institute of silicate materials. main research area: research of stone materials of latvian monuments, analysis of stone corrosion, supervision of restoration activities. address: riga technical university, institute of silicate materials, azenes street 14/24, lv-1048, riga, latvia. tel.: +371 670 89140 e-mail: vitina@ktf.rtu.lv lauma lindina – dr.sc.ing., researcher at riga technical university (rtu), faculty of material science and applied chemistry, institute of silicate materials. main research area: clay mineralogy and x-ray diffraction analysis. address: riga technical university, institute of silicate materials, azenes street 14/24, lv-1048, riga, latvia. tel.: +371 676 15560 e-mail: laumalindina@inbox.lv linda krage – dr.sc.ing., associate professor, leading researcher at riga technical university (rtu), faculty of material science and applied chemistry, institute of silicate materials. main research area: restoration and conservation of stone materials; inorganic binders. address: riga technical university, institute of silicate materials, azenes street 14/24, lv-1048, riga, latvia. tel.: +371 676 15560 e-mail: linda@ktf.rtu.lv journal of sustainable architecture and civil engineering 2018/2/23 86 *corresponding author: julius.endzelis@gmail.com comparison between modular building technology and traditional construction received 2018/08/24 accepted after revision 2018/11/05 journal of sustainable architecture and civil engineering vol. 2 / no. 23 / 2018 pp. 86-95 doi 10.5755/j01.sace.23.2.21579 comparison between modular building technology and traditional construction jsace 2/23 http://dx.doi.org/10.5755/j01.sace.23.2.21579 julius endzelis*, mindaugas daukšys kaunas university of technology, faculty of civil engineering and architecture studentu str. 48, lt-51367 kaunas, lithuania introduction this article presents a comparison of modular construction technology with traditional construction based on the results of the survey. the aim of the survey was to find out experts opinion about modular construction, the innovative way of building and its advantages and disadvantages compared to traditional building method. the results of the survey showed that modular construction has more pros than cons compared with the traditional construction method and is more economical and saves more time and materials. the most important criteria that demonstrates the clear advantage of modular construction technology is the duration of construction, the quality of work performed, and the safety of work. this research is based on master thesis topic. keywords: modular construction, metal frame module, wooden frame module, traditional construction. modern building technologies are so advanced that simply just by choosing the structure of a building it will be built in a few days or weeks. the construction time has been significantly shortened, construction has become more sustainable. modular construction technology (3d volumetric construction) is one such construction technology. every year, both investors and ordinary consumers are showing increasing interest in modular homes and it is quickly becoming the new way in home building comparing to the traditional construction. this type of construction has a lot of advantages against traditional construction, such as shorter construction time, higher quality and possibly saving some money. more and more clients want a multi-storey health care or educational institutions made out of modules. in the lithuanian market, the main companies involved in the production of modules are jsc „scandi house“, jsc „ryterna“, jsc „kagesa“, jsc „wilbergs group“. modular construction is a process in which several modules of the same house are manufactured at the factory, and at the same time construction site and foundation work is being carried out. the publication (modular building institute, 2010) present the factors that have the greatest impact on the productivity of the construction industry. one of these factors is the modular construction, which reduces the cost of the project, shortens the work schedules, improves the quality of the building and reduces the need for workers and material cost on the construction site. the authors (jellen and memari 2013) describe the types of modular homes, their construction advantages, applications and challenges in the modular home sector. smith (2016) describes non-site generated modules, their benefits, and when it‘s best to use them instead of traditional construction. generalova et al (2016) discusses the temporary use of modular elements in construction. 87 journal of sustainable architecture and civil engineering 2018/2/23 it is emphasized that modular structures can shorten the duration of a project, reduce costs and improve construction productivity. it is written about russia‘s extensive experience in the development of reinforced concrete modules. it also describes perspectives and relevance not only at low elevations, but also in the construction of multi-storey and high-rise modular constructions. the authors (shafari et al 2017) describes innovative, integrity-enhancing multi-storey building modular systems. zhang et al (2016) looks at the history of industrialization in the chinese construction industry and discusses the prospects for using bim (building information modelling) in modular and industrial construction. it discusses the use of advanced tools, including a 3d laser scanner to collect real-world information and to use robotized all-station (tacheometer) for quick installation. the authors (lopez and froese 2016) provide a detailed analysis of the cost of the two main categories of prefabricated houses – panel and modular. the main goal of the study is to provide information on the implications and compromises of both construction methods for construction of a single family home, as well as to determine which option is more cost-effective. ding et al (2017) describes the quasi-static cspsw (corrugated steel plate shear wall) method for walls with and without openings to assess seismic influences on walls. two different cases of side force countermeasures are discussed. several design recommendations are also provided, which will be useful for using the cspsw method in the seismic zone. the authors (mohsen et al 2008) discuss in their work with the simphony.net application‘s ability to analyze design and construction work. the analysis was carried out both before and after project implementation, in order to predict the construction efficiency and duration, and to give access to alternative construction scenarios. the authors (lee et al 2016) suggest optimizing the construction process at the factory stage using matrix of dependency structure, which takes into account the process approach based on construction information flow at work. kamali and hewage (2016) discusses the methodology used to identify and select appropriate life cycle indicators (spis) that value sustainability in the construction of modular and traditional homes. the authors identified spi indicators for assessing the life cycle of buildings. it also conducted a survey in its study to assess the application of sustainability indicators for comparing modular and traditional construction. the authors (molavi and barral 2016) provide a simple explanation of modular and panel systems and propose construction project design methods based on project type to avoid various disadvantages in sustainable modular construction. the authors (kamali and hewage 2016) discuss the production of different types of modules for production at the plant and for their assembly on the construction site. it also describes the benefits of modules such as time, life expectancy, price and nature conservation. matei (2017) writes about the next generation of “ten fold” modules that do not need to install a foundation or hire a crane. eagle (2014) writes about building a hospital using modules. the article also mentions the benefits of modular construction such as lower costs and time. sevenson (2015) writes about a 3d-printed and built modular house that can withstand a magnitude 9.0 earthquake, based on the richter scale. the authors (ngo et al 2009) describe the work done by the metal frame modular house in order to determine whether this construction method is more environmentally friendly. the results are compared with the usual construction method. the authors (larsson et al 2012) present a logical outline for an innovative architectural stacking methodology based on three swedish timber construction systems and how much stories each system is capable of producing which is up to 20 stories. aaron morby (2017) writes that tide construction, with funding from investor greystar, is planning to build modular building containing of two towers 44 and 38 storeys on former essex house site near to east croydon station, greater london. this work seeks to find out why in foreign countries the popular way of building is not promoted in the lithuania, to review the advantages and disadvantages of modular construction and the main criteria that determine the choice of modular construction technology. journal of sustainable architecture and civil engineering 2018/2/23 88 in the website https://docs.google.com/forms a survey was prepared with questions that help to uncover expert opinions about modular construction technology in comparison to traditional construction. three types of building construction were selected for the study as alternatives (fig. 1): _ calcium silicate bricks masonry building – a1. this is the most widespread construction method in lithuania and other neighboring countries. all walls (load bearing and not load bearing) of this building are masonry of ceramic or calcium silicate bricks. example of residential building is given in fig. 1a. _ wooden frame module – a2. these modules are made of wooden frame and are intended for the construction of one or multiple storeys. the module is made using high quality wood that meets the requirements of the standards used in the country. example of wooden frame module is given in fig. 1b (https://inhabitat.com). methods c) metal frame module building (lawson and ogden, 2008) building are masonry of ceramic or calcium silicate bricks. example of residential building is given in figure 1a.  wooden frame module – a2. these modules are made of wooden frame and are intended for the construction of one or multiple storeys. the module is made using high quality wood that meets the requirements of the standards used in the country. example of wooden frame module is given in figure 1b (https://inhabitat.com).  metal frame module – a3. the modules are made of metal frame and are designed for both lowrise and multi-storey buildings. the metal frame is designed to accommodate future loads. frame elements can be interconnected by screw couplings or welded together. example of metal frame module is given in figure 1c (lawson and ogden 2008). a) calcium silicate bricks masonry building (www.ober-haus.lt) b) wooden frame module building (https://inhabitat.com) c) metal frame module building (lawson and ogden, 2008) building are masonry of ceramic or calcium silicate bricks. example of residential building is given in figure 1a.  wooden frame module – a2. these modules are made of wooden frame and are intended for the construction of one or multiple storeys. the module is made using high quality wood that meets the requirements of the standards used in the country. example of wooden frame module is given in figure 1b (https://inhabitat.com).  metal frame module – a3. the modules are made of metal frame and are designed for both lowrise and multi-storey buildings. the metal frame is designed to accommodate future loads. frame elements can be interconnected by screw couplings or welded together. example of metal frame module is given in figure 1c (lawson and ogden 2008). a) calcium silicate bricks masonry building (www.ober-haus.lt) b) wooden frame module building (https://inhabitat.com) c) metal frame module building (lawson and ogden, 2008) building are masonry of ceramic or calcium silicate bricks. example of residential building is given in figure 1a.  wooden frame module – a2. these modules are made of wooden frame and are intended for the construction of one or multiple storeys. the module is made using high quality wood that meets the requirements of the standards used in the country. example of wooden frame module is given in figure 1b (https://inhabitat.com).  metal frame module – a3. the modules are made of metal frame and are designed for both lowrise and multi-storey buildings. the metal frame is designed to accommodate future loads. frame elements can be interconnected by screw couplings or welded together. example of metal frame module is given in figure 1c (lawson and ogden 2008). a) calcium silicate bricks masonry building (www.ober-haus.lt) b) wooden frame module building (https://inhabitat.com) c) metal frame module building (lawson and ogden, 2008) a) calcium silicate bricks masonry building (www.ober-haus.lt) b) wooden frame module building (https://inhabitat.com) _ metal frame module – a3. the modules are made of metal frame and are designed for both low-rise and multi-storey buildings. the metal frame is designed to accommodate future loads. frame elements can be interconnected by screw couplings or welded together. example of metal frame module is given in fig. 1c (lawson and ogden 2008). during the study, the wall and roof parts of each of the 3 possible variants were designed to meet the requirements of thermal resistance a ++ (fig. 2). following the design of the wall, using the autodesk revit software, 3 versions of the same 5 floor residential building were designed (modular wooden frame, modular metal frame and masonry building). outside dimensions of the building are 30.6x13.5x16.2m. all three versions of the residential building use paroc mineral wool as a thermal insulation. the only difference between versions is that modular buildings have thermal insulation between framing (fig. 3). both modular versions of a building contain 24 units in one floor (120 units in total for a building). by designing all three options, the autodesk revit program counted the cost of materials for each option, and the sistela program counted the construction cost of each option construction. fig. 1 three types of building construction 89 journal of sustainable architecture and civil engineering 2018/2/23 figure 1. three types of building construction during the study, the wall and roof parts of each of the 3 possible variants were designed to meet the requirements of thermal resistance a ++ (figure 2). following the design of the wall, using the autodesk revit software, 3 versions of the same 5 floor residential building were designed (modular wooden frame, modular metal frame and masonry building). a) 3d view b) a-a cros-section view c) floor plan view d) b-b cros-section view figure 2. example of 5-storey residential building outside dimensions of the building are 30.6x13.5x16.2m. all three versions of the residential building use paroc mineral wool as a thermal insulation. the only difference between versions is that modular buildings have thermal insulation between framing (figure 3). both modular versions of a building contain 24 units in one floor (120 units in total for a building). by designing all three options, the autodesk revit program counted the cost of materials for each option, and the sistela program counted the construction cost of each option construction. a b b a figure 1. three types of building construction during the study, the wall and roof parts of each of the 3 possible variants were designed to meet the requirements of thermal resistance a ++ (figure 2). following the design of the wall, using the autodesk revit software, 3 versions of the same 5 floor residential building were designed (modular wooden frame, modular metal frame and masonry building). a) 3d view b) a-a cros-section view c) floor plan view d) b-b cros-section view figure 2. example of 5-storey residential building outside dimensions of the building are 30.6x13.5x16.2m. all three versions of the residential building use paroc mineral wool as a thermal insulation. the only difference between versions is that modular buildings have thermal insulation between framing (figure 3). both modular versions of a building contain 24 units in one floor (120 units in total for a building). by designing all three options, the autodesk revit program counted the cost of materials for each option, and the sistela program counted the construction cost of each option construction. a b b a c) floor plan view d) b-b cros-section view figure 2. example of 5-storey residential building a a b b c) floor plan view d) b-b cros-section view figure 2. example of 5-storey residential building a a b b a) 3d view b) a-a cros-section view c) floor plan view d) b-b cros-section view fig. 2 example of 5-storey residential building after calculating the estimate of each possibility, it was possible to see the price of 1m2 living space, the duration of work, the need of human resources and mechanisms. the following evaluation criteria were selected for measuring the comparison of selected type of building construction: _ k1 – 1m 2 installation cost, eur/m2; _ k2 – construction time (work carried out consistently), work days; _ k3 – work safety during construction work, points; _ k4 – environmental protection, points; _ k5 – man-hours, h/m 2, h/m2; _ k6 – quality of work performed, points; _ k7 – machine-hours, h/m 2. evaluation criteria for each type of building construction are different (table 1). the following multi-criteria evaluations were used to conduct the study: _ expert multi-criteria assessment – this research method has allowed to identify the most important criteria using the survey; _ theoretical multi-criteria assessment – this evaluation method has allowed to identify the most important criteria from the collected data; _ complex multi-criteria assessment – this assessment method has allowed to identify the most important criteria using the results of expert and theoretical evaluation; _ multi-criterion utility method – this evaluation method has made it possible to determine which alternative is the rational option from the three analysed options. journal of sustainable architecture and civil engineering 2018/2/23 90 b) roof system details figure 3. examples of structure system details of 3 versions of the same residential building after calculating the estimate of each possibility, it was possible to see the price of 1m2 living space, the duration of work, the need of human resources and mechanisms. the following evaluation criteria were selected for measuring the comparison of selected type of building construction:  k1 – 1m2 installation cost, eur/m2;  k2 – construction time (work carried out consistently), work days;  k3 – work safety during construction work, points;  k4 – environmental protection, points;  k5 – man-hours, h/m2, h/m2;  k6 – quality of work performed, points;  k7 – machine-hours, h/m2. evaluation criteria for each type of building construction are different (table 1). table 1. comparison of selected type of building construction type of building construction options calcium silicate bricks masonry building wooden frame module metal frame module 1m2 installation cost, eur/m2 734.77 704.74 679.28 construction time, work days; 210 126 126 work safety during construction work, points 5 8 8 environmental protection, points 5 8 8 man-hours, h/m2, h/m2 9.8 5.2 5.4 quality of work performed, points 6 8 8 machine-hours, h/m2 1.49 0.89 0.79 78 65 11 2 4 31 10 9 4 6 73 51 89 2 1. gypsum plaster d=20mm, λ=0.57w/mk; 2. monolithic concrete – d=200mm, λ=2.5 w/mk; 3. slope forming thermal insulation layer 4. tyvek airguard reflective; 5. paroc extra plus – d=500mm, λ=0,036w/mk; 6. paroc cortex – d=50mm, λ=0.033w/mk; 7. mida bipol – d=8mm, λ=0.17w/mk; 1. gypsum plaster d=20mm, λ=0.57w/mk; 2. osb panel – d=10mm, λ=0.13w/mk; 3. cross laminated timber 30x50mm, every 1200mm λ=0.18w/mk; 4. paroc extra plus – d=30mm, λ=0,036w/mk; 5. tyvek airguard reflective; 6. cross laminated timber 150x50mm, every 1200mm λ=0.18w/mk; 7. paroc extra plus – d=150mm, λ=0,036w/mk; 8. slope forming thermal insulation layer 9. tyvek housewrap 10. paroc extra plus – d=350mm, λ=0.036w/mk; 11. mida bipol – d=8mm, λ=0.17w/mk; 1. gypsum plaster d=20mm, λ=0.57w/mk; 2. osb panel – d=10mm, λ=0.13w/mk; 3. tyvek airguard reflective; 4. square metal profile 100x100mm, every 2000mm λ=50w/mk; 5. paroc extra plus – d=100mm, λ=0,036w/mk; 6. slope forming thermal insulation layer 7. tyvek housewrap 8. paroc extra plus – d=550mm, λ=0.033w/mk; 9. mida bipol – d=8mm, λ=0.17w/mk; calcium silicate bricks masonry building wooden frame module building metal frame module building a) wall system details 6 7 5 3 1 4 2 9 6 7 10 3 8 5 4 2 1 7 10 3 5 8 4 2 1 6 9 1. gypsum plaster (r=1300kgm3) d=20mm, λ=0.57w/mk; 2. ceramic blocks keraterm 25 – d=250mm, λ=0.22w/mk; 3. tyvek airguard reflective; 4. paroc extra plus – d=320mm, λ=0.036w/mk; 5. paroc cortex – d=50mm, λ=0.033w/mk; 6. decorative plaster – d=30mm, λ=0.8 w/mk; 7. insulation pin – d=450mm; 1. gypsum boards (r=1300kgm3) d=25mm, λ=0.57w/mk; 2. tyvek airguard reflective; 3. paroc extra plus – d=100mm, λ=0.036w/mk; 4. cross laminated timber 100x100mm, every 1200mm λ=0.18w/mk; 5. osb panel – d=10mm, λ=0.13w/mk; 6. paroc extra plus – d=300mm, λ=0.036w/mk; 7. paroc cortex – d=50mm, λ=0.033w/mk; 8. fully ventilated air gap / t profile – d=30mm; 9. façade panel tectiva 10. insulation pins – d=400mm; 1. gypsum board (r=1300kgm3) d=25mm, λ=0.57w/mk; 2. tyvek airguard reflective; 3. paroc extra plus – d=100mm, λ=0.036w/mk; 4. square metal profile 100x100mm, every 2000mm λ=50 w/mk; 5. osb panel – d=10mm, λ=0.13w/mk; 6. paroc extra plus – d=350mm, λ=0.036w/mk; 7. paroc cortex – d=50mm, λ=0.033w/mk; 8. fully ventilated air gap / t profile – d=30mm; 9. fasadinė plokštė tectiva 10. insulation pins – d=450mm; calcium silicate bricks masonry building wooden frame module building metal frame module building a) wall system details 6 7 5 3 1 4 2 9 6 7 10 3 8 5 4 2 1 7 10 3 5 8 4 2 1 6 9 1. gypsum plaster (r=1300kgm3) d=20mm, λ=0.57w/mk; 2. ceramic blocks keraterm 25 – d=250mm, λ=0.22w/mk; 3. tyvek airguard reflective; 4. paroc extra plus – d=320mm, λ=0.036w/mk; 5. paroc cortex – d=50mm, λ=0.033w/mk; 6. decorative plaster – d=30mm, λ=0.8 w/mk; 7. insulation pin – d=450mm; 1. gypsum boards (r=1300kgm3) d=25mm, λ=0.57w/mk; 2. tyvek airguard reflective; 3. paroc extra plus – d=100mm, λ=0.036w/mk; 4. cross laminated timber 100x100mm, every 1200mm λ=0.18w/mk; 5. osb panel – d=10mm, λ=0.13w/mk; 6. paroc extra plus – d=300mm, λ=0.036w/mk; 7. paroc cortex – d=50mm, λ=0.033w/mk; 8. fully ventilated air gap / t profile – d=30mm; 9. façade panel tectiva 10. insulation pins – d=400mm; 1. gypsum board (r=1300kgm3) d=25mm, λ=0.57w/mk; 2. tyvek airguard reflective; 3. paroc extra plus – d=100mm, λ=0.036w/mk; 4. square metal profile 100x100mm, every 2000mm λ=50 w/mk; 5. osb panel – d=10mm, λ=0.13w/mk; 6. paroc extra plus – d=350mm, λ=0.036w/mk; 7. paroc cortex – d=50mm, λ=0.033w/mk; 8. fully ventilated air gap / t profile – d=30mm; 9. fasadinė plokštė tectiva 10. insulation pins – d=450mm; calcium silicate bricks masonry building wooden frame module building metal frame module building a) wall system details 6 7 5 3 1 4 2 9 6 7 10 3 8 5 4 2 1 7 10 3 5 8 4 2 1 6 9 1. gypsum plaster (r=1300kgm3) d=20mm, λ=0.57w/mk; 2. ceramic blocks keraterm 25 – d=250mm, λ=0.22w/mk; 3. tyvek airguard reflective; 4. paroc extra plus – d=320mm, λ=0.036w/mk; 5. paroc cortex – d=50mm, λ=0.033w/mk; 6. decorative plaster – d=30mm, λ=0.8 w/mk; 7. insulation pin – d=450mm; 1. gypsum boards (r=1300kgm3) d=25mm, λ=0.57w/mk; 2. tyvek airguard reflective; 3. paroc extra plus – d=100mm, λ=0.036w/mk; 4. cross laminated timber 100x100mm, every 1200mm λ=0.18w/mk; 5. osb panel – d=10mm, λ=0.13w/mk; 6. paroc extra plus – d=300mm, λ=0.036w/mk; 7. paroc cortex – d=50mm, λ=0.033w/mk; 8. fully ventilated air gap / t profile – d=30mm; 9. façade panel tectiva 10. insulation pins – d=400mm; 1. gypsum board (r=1300kgm3) d=25mm, λ=0.57w/mk; 2. tyvek airguard reflective; 3. paroc extra plus – d=100mm, λ=0.036w/mk; 4. square metal profile 100x100mm, every 2000mm λ=50 w/mk; 5. osb panel – d=10mm, λ=0.13w/mk; 6. paroc extra plus – d=350mm, λ=0.036w/mk; 7. paroc cortex – d=50mm, λ=0.033w/mk; 8. fully ventilated air gap / t profile – d=30mm; 9. fasadinė plokštė tectiva 10. insulation pins – d=450mm; 1. gypsum plaster d=20mm, λ=0.57w/mk; 2. osb panel – d=10mm, λ=0.13w/mk; 3. tyvek airguard reflective; 4. square metal profile 100x100mm, every 2000mm λ=50w/mk; 5. paroc extra plus – d=100mm, λ=0,036w/ mk; 6. slope forming thermal insulation layer 7. tyvek housewrap 8. paroc extra plus – d=550mm, λ=0.033w/ mk; 9. mida bipol – d=8mm, λ=0.17w/mk; 1. gypsum plaster (r=1300kgm3) d=20mm, λ=0.57w/mk; 2. ceramic blocks keraterm 25 – d=250mm, λ=0.22w/mk; 3. tyvek airguard reflective; 4. paroc extra plus – d=320mm, λ=0.036w/mk; 5. paroc cortex – d=50mm, λ=0.033w/mk; 6. decorative plaster – d=30mm, λ=0.8 w/mk; 7. insulation pin – d=450mm; 1. gypsum boards (r=1300kgm3) d=25mm, λ=0.57w/mk; 2. tyvek airguard reflective; 3. paroc extra plus – d=100mm, λ=0.036w/ mk; 4. cross laminated timber 100x100mm, every 1200mm λ=0.18w/mk; 5. osb panel – d=10mm, λ=0.13w/mk; 6. paroc extra plus – d=300mm, λ=0.036w/mk; 7. paroc cortex – d=50mm, λ=0.033w/mk; 8. fully ventilated air gap / t profile – d=30mm; 9. façade panel tectiva 10.insulation pins – d=400mm; 1. gypsum board (r=1300kgm3) d=25mm, λ=0.57w/mk; 2. tyvek airguard reflective; 3. paroc extra plus – d=100mm, λ=0.036w/ mk; 4. square metal profile 100x100mm, every 2000mm λ=50 w/mk; 5. osb panel – d=10mm, λ=0.13w/mk; 6. paroc extra plus – d=350mm, λ=0.036w/mk; 7. paroc cortex – d=50mm, λ=0.033w/mk; 8. fully ventilated air gap / t profile – d=30mm; 9. fasadinė plokštė tectiva 10. insulation pins – d=450mm; 1. gypsum plaster d=20mm, λ=0.57w/mk; 2. monolithic concrete – d=200mm, λ=2.5 w/mk; 3. slope forming thermal insulation layer 4. tyvek airguard reflective; 5. paroc extra plus – d=500mm, λ=0,036w/mk; 6. paroc cortex – d=50mm, λ=0.033w/mk; 7. mida bipol – d=8mm, λ=0.17w/mk; 1. gypsum plaster d=20mm, λ=0.57w/mk; 2. osb panel – d=10mm, λ=0.13w/mk; 3. cross laminated timber 30x50mm, every 1200mm λ=0.18w/mk; 4. paroc extra plus – d=30mm, λ=0,036w/mk; 5. tyvek airguard reflective; 6. cross laminated timber 150x50mm, every 1200mm λ=0.18w/mk; 7. paroc extra plus – d=150mm, λ=0,036w/mk; 8. slope forming thermal insulation layer 9. tyvek housewrap 10. paroc extra plus – d=350mm, λ=0.036w/mk; 11. mida bipol – d=8mm, λ=0.17w/mk; a) wall system details b) roof system details fig. 3. examples of structure system details of 3 versions of the same residential building 91 journal of sustainable architecture and civil engineering 2018/2/23 table 1 comparison of selected type of building construction type of building construction options calcium silicate bricks masonry building wooden frame module metal frame module 1m2 installation cost, eur/m2 734.77 704.74 679.28 construction time, work days; 210 126 126 work safety during construction work, points 5 8 8 environmental protection, points 5 8 8 man-hours, h/m2, h/m2 9.8 5.2 5.4 quality of work performed, points 6 8 8 machine-hours, h/m2 1.49 0.89 0.79 the distribution of respondents who participated in the survey by work experience in the field of construction is presented in fig. 4. in total 20 respondents participated in the survey. 40% of the respondents belonged to a group of 1-5 years of experience, 5% belonged to a group of 6-10 years of experience, 45% belonged to a group of 11-20 years of experience, and 10% of the respondents belonged to a group of 21 and more years of experience. it can be seen that results fig. 4 distribution of respondents according to available work experience in the field of construction the following multi-criteria evaluations were used to conduct the study:  expert multi-criteria assessment – this research method has allowed to identify the most important criteria using the survey;  theoretical multi-criteria assessment – this evaluation method has allowed to identify the most important criteria from the collected data;  complex multi-criteria assessment – this assessment method has allowed to identify the most important criteria using the results of expert and theoretical evaluation;  multi-criterion utility method – this evaluation method has made it possible to determine which alternative is the rational option from the three analysed options. results the distribution of respondents who participated in the survey by work experience in the field of construction is presented in figure 4. in total 20 respondents participated in the survey. 40% of the respondents belonged to a group of 1-5 years of experience, 5% belonged to a group of 6-10 years of experience, 45% belonged to a group of 11-20 years of experience, and 10% of the respondents belonged to a group of 21 and more years of experience. it can be seen that the vast majority of respondents were 11-20 years old with experience in the field of construction. figure 4. distribution of respondents according to available work experience in the field of construction the distribution of the respondents view on the survey question is presented in figure 5. a b 40% 5% 45% 10% respondents work experience in the field of construction 1-5 yrs 6-10 yrs 11-20 yrs 21yrs and more 20% 55% 25% which way of the construction is cheaper? rate from 0 to 2 points. give a higher score for a cheaper way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 10% 45% 45% which way do you think the construction takes less time? rate from 0 to 2 points. give a higher score for a faster way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] the vast majority of respondents were 11-20 years old with experience in the field of construction. the distribution of the respondents view on the survey question is presented in fig. 5. the fig. 5 shows opinion of 20 experts. 7 questions were given to the each of the experts where every question represented different criteria for the assessment. as the figure shows most of the respondents choose wooden frame module as more favorable survey answer. after an expert evaluation of the criteria, it was obtained that the construction time, the value of which is 20.5%, is the most important criterion, second most important is the value of the installation of 1m2, which is 19.8% (fig. 6). the quality of performed works (18.4%), safety of work during construction (15.3%), and environmental protection (11.5%) are in the order of success. the smallest value is the human work of 1m2 installed (8.6%) and the working time of machinery for 1m2 installation (6.0%). after an expert evaluation, the coefficient of concordance is 0.843, which indicates that the expert opinion is evenly distributed and the survey is reliable. after evaluation of the theoretical criteria, it was obtained that the main criteria is the human work for 1 m2 installed, the value of which is 26.68%, the importance of mechanisms for 1 m2 installed, having a value of 24.86%, is after it (fig. 7). the construction time is 18.22%, the environmental protection and work safety is 12.5%, and the quality of work performed is 4.94%. the lowest value is 1m2 installation cost 0.3%. after completing the complex criterion evaluation, it was obtained that construction time, the significance of which is 31.63%, is the most important criteria, and the importance of the human work for 1 m2 installed is still important, with a value of 19.39% (fig. 8). the following is in order of safety of works during construction work 16.15%, the duration of machinery working on 1m2 is 12.55%, and the environmental protection 12.11%. the minimum value is the quality of work performed 7.68% and 1m2 installation cost 0.5%. next, the significance was evaluated of all alternatives using performance-degree comparison. after an expert comparison of the alternatives, the most important alternative was the modular design of the building of wooden frame (a2) with a value of 99.68%, second is the modules with journal of sustainable architecture and civil engineering 2018/2/23 92 the following multi-criteria evaluations were used to conduct the study:  expert multi-criteria assessment – this research method has allowed to identify the most important criteria using the survey;  theoretical multi-criteria assessment – this evaluation method has allowed to identify the most important criteria from the collected data;  complex multi-criteria assessment – this assessment method has allowed to identify the most important criteria using the results of expert and theoretical evaluation;  multi-criterion utility method – this evaluation method has made it possible to determine which alternative is the rational option from the three analysed options. results the distribution of respondents who participated in the survey by work experience in the field of construction is presented in figure 4. in total 20 respondents participated in the survey. 40% of the respondents belonged to a group of 1-5 years of experience, 5% belonged to a group of 6-10 years of experience, 45% belonged to a group of 11-20 years of experience, and 10% of the respondents belonged to a group of 21 and more years of experience. it can be seen that the vast majority of respondents were 11-20 years old with experience in the field of construction. figure 4. distribution of respondents according to available work experience in the field of construction the distribution of the respondents view on the survey question is presented in figure 5. a b 40% 5% 45% 10% respondents work experience in the field of construction 1-5 yrs 6-10 yrs 11-20 yrs 21yrs and more 20% 55% 25% which way of the construction is cheaper? rate from 0 to 2 points. give a higher score for a cheaper way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 10% 45% 45% which way do you think the construction takes less time? rate from 0 to 2 points. give a higher score for a faster way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] the following multi-criteria evaluations were used to conduct the study:  expert multi-criteria assessment – this research method has allowed to identify the most important criteria using the survey;  theoretical multi-criteria assessment – this evaluation method has allowed to identify the most important criteria from the collected data;  complex multi-criteria assessment – this assessment method has allowed to identify the most important criteria using the results of expert and theoretical evaluation;  multi-criterion utility method – this evaluation method has made it possible to determine which alternative is the rational option from the three analysed options. results the distribution of respondents who participated in the survey by work experience in the field of construction is presented in figure 4. in total 20 respondents participated in the survey. 40% of the respondents belonged to a group of 1-5 years of experience, 5% belonged to a group of 6-10 years of experience, 45% belonged to a group of 11-20 years of experience, and 10% of the respondents belonged to a group of 21 and more years of experience. it can be seen that the vast majority of respondents were 11-20 years old with experience in the field of construction. figure 4. distribution of respondents according to available work experience in the field of construction the distribution of the respondents view on the survey question is presented in figure 5. a b 40% 5% 45% 10% respondents work experience in the field of construction 1-5 yrs 6-10 yrs 11-20 yrs 21yrs and more 20% 55% 25% which way of the construction is cheaper? rate from 0 to 2 points. give a higher score for a cheaper way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 10% 45% 45% which way do you think the construction takes less time? rate from 0 to 2 points. give a higher score for a faster way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] c d e f g figure 5. distribution of respondents' opinions according to the submitted questionnaire questions the figure 5 shows opinion of 20 experts. 7 questions were given to the each of the experts where every question represented different criteria for the assessment. as the figure shows most of the respondents choose wooden frame module as more favorable survey answer. after an expert evaluation of the criteria, it was obtained that the construction time, the value of which is 20.5%, is the most important criterion, second most important is the value of the installation of 1m2, which is 19.8% (figure 6). the quality of performed works (18.4%), safety of work during construction (15.3%), and environmental protection (11.5%) are in the order of success. the smallest value is the human work of 1m2 installed (8.6%) and the working time of machinery for 1m2 installation (6.0%). 35% 55% 10% which construction method when building a house has the smallest chance of an accident to happen? rate from 0 to 2 points. give a higher score to a safer way. [calcium silicate bricks masonry building] [wooden frame module] 0% 60% 40% which way of building a house will leave the least amount of construction waste and air pollution? rate from 0 to 2 points. give a higher score to a greener way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 10% 40%50% which way of building a house on a construction site will require the least human work to install 1m2? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 25% 30% 45% which way will the house be better built(quality wise)? rate from 0 to 2 points. give a higher score a better way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 30% 45% 25% which method of construction will require the least machinery? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] c d e f g figure 5. distribution of respondents' opinions according to the submitted questionnaire questions the figure 5 shows opinion of 20 experts. 7 questions were given to the each of the experts where every question represented different criteria for the assessment. as the figure shows most of the respondents choose wooden frame module as more favorable survey answer. after an expert evaluation of the criteria, it was obtained that the construction time, the value of which is 20.5%, is the most important criterion, second most important is the value of the installation of 1m2, which is 19.8% (figure 6). the quality of performed works (18.4%), safety of work during construction (15.3%), and environmental protection (11.5%) are in the order of success. the smallest value is the human work of 1m2 installed (8.6%) and the working time of machinery for 1m2 installation (6.0%). 35% 55% 10% which construction method when building a house has the smallest chance of an accident to happen? rate from 0 to 2 points. give a higher score to a safer way. [calcium silicate bricks masonry building] [wooden frame module] 0% 60% 40% which way of building a house will leave the least amount of construction waste and air pollution? rate from 0 to 2 points. give a higher score to a greener way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 10% 40%50% which way of building a house on a construction site will require the least human work to install 1m2? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 25% 30% 45% which way will the house be better built(quality wise)? rate from 0 to 2 points. give a higher score a better way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 30% 45% 25% which method of construction will require the least machinery? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] c d e f g figure 5. distribution of respondents' opinions according to the submitted questionnaire questions the figure 5 shows opinion of 20 experts. 7 questions were given to the each of the experts where every question represented different criteria for the assessment. as the figure shows most of the respondents choose wooden frame module as more favorable survey answer. after an expert evaluation of the criteria, it was obtained that the construction time, the value of which is 20.5%, is the most important criterion, second most important is the value of the installation of 1m2, which is 19.8% (figure 6). the quality of performed works (18.4%), safety of work during construction (15.3%), and environmental protection (11.5%) are in the order of success. the smallest value is the human work of 1m2 installed (8.6%) and the working time of machinery for 1m2 installation (6.0%). 35% 55% 10% which construction method when building a house has the smallest chance of an accident to happen? rate from 0 to 2 points. give a higher score to a safer way. [calcium silicate bricks masonry building] [wooden frame module] 0% 60% 40% which way of building a house will leave the least amount of construction waste and air pollution? rate from 0 to 2 points. give a higher score to a greener way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 10% 40%50% which way of building a house on a construction site will require the least human work to install 1m2? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 25% 30% 45% which way will the house be better built(quality wise)? rate from 0 to 2 points. give a higher score a better way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 30% 45% 25% which method of construction will require the least machinery? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] c d e f g figure 5. distribution of respondents' opinions according to the submitted questionnaire questions the figure 5 shows opinion of 20 experts. 7 questions were given to the each of the experts where every question represented different criteria for the assessment. as the figure shows most of the respondents choose wooden frame module as more favorable survey answer. after an expert evaluation of the criteria, it was obtained that the construction time, the value of which is 20.5%, is the most important criterion, second most important is the value of the installation of 1m2, which is 19.8% (figure 6). the quality of performed works (18.4%), safety of work during construction (15.3%), and environmental protection (11.5%) are in the order of success. the smallest value is the human work of 1m2 installed (8.6%) and the working time of machinery for 1m2 installation (6.0%). 35% 55% 10% which construction method when building a house has the smallest chance of an accident to happen? rate from 0 to 2 points. give a higher score to a safer way. [calcium silicate bricks masonry building] [wooden frame module] 0% 60% 40% which way of building a house will leave the least amount of construction waste and air pollution? rate from 0 to 2 points. give a higher score to a greener way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 10% 40%50% which way of building a house on a construction site will require the least human work to install 1m2? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 25% 30% 45% which way will the house be better built(quality wise)? rate from 0 to 2 points. give a higher score a better way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 30% 45% 25% which method of construction will require the least machinery? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] c d e f g figure 5. distribution of respondents' opinions according to the submitted questionnaire questions the figure 5 shows opinion of 20 experts. 7 questions were given to the each of the experts where every question represented different criteria for the assessment. as the figure shows most of the respondents choose wooden frame module as more favorable survey answer. after an expert evaluation of the criteria, it was obtained that the construction time, the value of which is 20.5%, is the most important criterion, second most important is the value of the installation of 1m2, which is 19.8% (figure 6). the quality of performed works (18.4%), safety of work during construction (15.3%), and environmental protection (11.5%) are in the order of success. the smallest value is the human work of 1m2 installed (8.6%) and the working time of machinery for 1m2 installation (6.0%). 35% 55% 10% which construction method when building a house has the smallest chance of an accident to happen? rate from 0 to 2 points. give a higher score to a safer way. [calcium silicate bricks masonry building] [wooden frame module] 0% 60% 40% which way of building a house will leave the least amount of construction waste and air pollution? rate from 0 to 2 points. give a higher score to a greener way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 10% 40%50% which way of building a house on a construction site will require the least human work to install 1m2? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 25% 30% 45% which way will the house be better built(quality wise)? rate from 0 to 2 points. give a higher score a better way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] 30% 45% 25% which method of construction will require the least machinery? rate from 0 to 2 points. give a higher score to a less demanding way. [calcium silicate bricks masonry building] [wooden frame module] [metal frame module] metal frame (a3) of 98.48% by importance (fig. 9). the least significant alternative is a traditional calcium silicate bricks masonry building (a1) with a value of 68.76%. after theoretical comparison of the alternatives the most important alternative is the modular building of the wooden modules (a2) with a value of 99.41%, followed by the metal frame modules (a3) with the value of 97.2% (fig. 10). the least significant alternative is a traditional calcium silicate bricks masonry building (a1) with a value of 64.42%. fig. 5 distribution of respondents’ opinions according to the submitted questionnaire questions a) b) c) d) e) f) g) 93 journal of sustainable architecture and civil engineering 2018/2/23 after an expert evaluation, the coefficient of concordance is 0.843, which indicates that the expert opinion is evenly distributed and the survey is reliable. figure 6. results of expert multi-criteria assessment after evaluation of the theoretical criteria, it was obtained that the main criteria is the human work for 1 m2 installed, the value of which is 26.68%, the importance of mechanisms for 1 m2 installed, having a value of 24.86%, is after it (figure 7). the construction time is 18.22%, the environmental protection and work safety is 12.5%, and the quality of work performed is 4.94%. the lowest value is 1m2 installation cost 0.3%. figure 7. results of theoretical multi-criteria assessment after completing the complex criterion evaluation, it was obtained that construction time, the significance of which is 31.63%, is the most important criteria, and the importance of the human work for 1 m2 installed is still important, with a value of 19.39% (figure 8). the following is in order of safety of works during construction work 16.15%, the duration of machinery working on 1m2 is 12.55%, and 19,81 20,53 15,27 11,46 8,59 18,38 5,97 0 5 10 15 20 25 k1, 1m2 installation cost (eur / m2) k2, construction time, (work days) k3, work safety during construction work (points) k4, environmental protection (points) k5, man hours (h/m2) k6, quality of work performed (points) k7, machine hours, (h/m2) pe rc en ta ge expert multi-criteria assessment 0,30 18,22 12,50 12,50 26,68 4,94 24,86 0 5 10 15 20 25 30 k1, 1m2 installation cost (eur / m2) k2, construction time, (work days) k3, work safety during construction work (points) k4, environmental protection (points) k5, manhours(h/m2) k6, quality of work performed (points) k7, machinehours (h/m2) pe rc en ta ge theoretical multi-criteria assessment after an expert evaluation, the coefficient of concordance is 0.843, which indicates that the expert opinion is evenly distributed and the survey is reliable. figure 6. results of expert multi-criteria assessment after evaluation of the theoretical criteria, it was obtained that the main criteria is the human work for 1 m2 installed, the value of which is 26.68%, the importance of mechanisms for 1 m2 installed, having a value of 24.86%, is after it (figure 7). the construction time is 18.22%, the environmental protection and work safety is 12.5%, and the quality of work performed is 4.94%. the lowest value is 1m2 installation cost 0.3%. figure 7. results of theoretical multi-criteria assessment after completing the complex criterion evaluation, it was obtained that construction time, the significance of which is 31.63%, is the most important criteria, and the importance of the human work for 1 m2 installed is still important, with a value of 19.39% (figure 8). the following is in order of safety of works during construction work 16.15%, the duration of machinery working on 1m2 is 12.55%, and 19,81 20,53 15,27 11,46 8,59 18,38 5,97 0 5 10 15 20 25 k1, 1m2 installation cost (eur / m2) k2, construction time, (work days) k3, work safety during construction work (points) k4, environmental protection (points) k5, man hours (h/m2) k6, quality of work performed (points) k7, machine hours, (h/m2) pe rc en ta ge expert multi-criteria assessment 0,30 18,22 12,50 12,50 26,68 4,94 24,86 0 5 10 15 20 25 30 k1, 1m2 installation cost (eur / m2) k2, construction time, (work days) k3, work safety during construction work (points) k4, environmental protection (points) k5, manhours(h/m2) k6, quality of work performed (points) k7, machinehours (h/m2) pe rc en ta ge theoretical multi-criteria assessment the environmental protection 12.11%. the minimum value is the quality of work performed 7.68% and 1m2 installation cost 0.5%. figure 8. results of complex multi-criteria assessment next, the significance was evaluated of all alternatives using performance-degree comparison. after an expert comparison of the alternatives, the most important alternative was the modular design of the building of wooden frame (a2) with a value of 99.68%, second is the modules with metal frame (a3) of 98.48% by importance (figure 9). the least significant alternative is a traditional calcium silicate bricks masonry building (a1) with a value of 68.76%. figure 9. comparison of the degrees of utility of alternatives according to the experimental significance of the schedule 0,50 31,63 16,15 12,11 19,39 7,68 12,55 0 5 10 15 20 25 30 35 k1, 1m2 installation cost (eur / m2) k2, construction time, (work days) k3, work safety during construction work (points) k4, environmental protection (points) k5, manhours(h/m2) k6, quality of work performed (points) k7, machinehours (h/m2) pe rc en ta ge complex multi-criteria assessment 68,76 99,68 98,48 0 20 40 60 80 100 120 a1, calcium silicate bricks masonry building a2, wooden frame module a3, metal frame module pe rc en ta ge experimental alternative significance fig. 6 results of expert multi-criteria assessment fig. 7 results of theoretical multi-criteria assessment fig. 8 results of complex multi-criteria assessment journal of sustainable architecture and civil engineering 2018/2/23 94 the complex alternative comparison has shown that the most important alternative is the modular building with the wooden frame (a2) with value of 99.63%, followed by the modules of the metal frame modular building (a3), which is 98.32%. the least significant alternative is a traditional calcium silicate bricks masonry building (a1) with a value of 68.16%. fig. 9 comparison of the degrees of utility of alternatives according to the experimental significance of the schedule fig. 10 comparison of degrees of utility of alternatives according to the complex significance the environmental protection 12.11%. the minimum value is the quality of work performed 7.68% and 1m2 installation cost 0.5%. figure 8. results of complex multi-criteria assessment next, the significance was evaluated of all alternatives using performance-degree comparison. after an expert comparison of the alternatives, the most important alternative was the modular design of the building of wooden frame (a2) with a value of 99.68%, second is the modules with metal frame (a3) of 98.48% by importance (figure 9). the least significant alternative is a traditional calcium silicate bricks masonry building (a1) with a value of 68.76%. figure 9. comparison of the degrees of utility of alternatives according to the experimental significance of the schedule 0,50 31,63 16,15 12,11 19,39 7,68 12,55 0 5 10 15 20 25 30 35 k1, 1m2 installation cost (eur / m2) k2, construction time, (work days) k3, work safety during construction work (points) k4, environmental protection (points) k5, manhours(h/m2) k6, quality of work performed (points) k7, machinehours (h/m2) pe rc en ta ge complex multi-criteria assessment 68,76 99,68 98,48 0 20 40 60 80 100 120 a1, calcium silicate bricks masonry building a2, wooden frame module a3, metal frame module pe rc en ta ge experimental alternative significance after theoretical comparison of the alternatives the most important alternative is the modular building of the wooden modules (a2) with a value of 99.41%, followed by the metal frame modules (a3) with the value of 97.2% (figure 10). the least significant alternative is a traditional calcium silicate bricks masonry building (a1) with a value of 64.42%. figure 10. comparison of degrees of utility of alternatives according to the complex significance the complex alternative comparison has shown that the most important alternative is the modular building with the wooden frame (a2) with value of 99.63%, followed by the modules of the metal frame modular building (a3), which is 98.32%. the least significant alternative is a traditional calcium silicate bricks masonry building (a1) with a value of 68.16%. conclusions 1. coefficient of concordance of the survey is 0.843, which indicates that the expert opinion is evenly distributed and the survey is reliable. most of the respondents choose wooden frame module as more favorable survey answer 2. using complex criteria evaluation, the most important criteria is construction time (k2), the significance of which is 31.63%, followed by the man-hours (k5) with a value of 19.39%. the following is in order of work safety during construction work (k3) 16.15%, the machine-hours (k7) is 12.55%, and the environmental protection (k4) 12.11%. the minimum value is the quality of work performed (k6) 7.68% and 1m2 installation cost (k1) 0.5%. 3. using complex alternative comparison the most important alternative is the modular building with the wooden frame (a2) with value of 99.63%. references a. c. jellen, a. m. memari. the state-of-the-art application of modular construction to multi-story residential buildings, 1st residential building design & construction conference – february 20-21, 2013 at sands casino resort, bethlehem, 2013; 284-293. a. morby. green light for world's tallest modular tower in croydon. construction enquirer, 2017, available at: https://www.constructionenquirer.com/2017/12/04/green-light-for-worlds-tallest-modular-tower-incroydon/ 68,16 99,63 98,32 0 20 40 60 80 100 120 a1, calcium silicate bricks masonry building a2, wooden frame module a3, metal frame module pe rc en ta ge complex alternative significance conclusions 1 coefficient of concordance of the survey is 0.843, which indicates that the expert opinion is evenly distributed and the survey is reliable. most of the respondents choose wooden frame module as more favorable survey answer 2 using complex criteria evaluation, the most important criteria is construction time (k2), the significance of which is 31.63%, followed by the man-hours (k5) with a value of 19.39%. the following is in order of work safety during construction work (k3) 16.15%, the machine-hours (k7) is 12.55%, and the environmental protection (k4) 12.11%. the minimum value is the quality of work performed (k6) 7.68% and 1m2 installation cost (k1) 0.5%. 3 using complex alternative comparison the most important alternative is the modular building with the wooden frame (a2) with value of 99.63%. 95 journal of sustainable architecture and civil engineering 2018/2/23 references a. c. jellen, a. m. memari. the state-of-the-art application of modular construction to multi-story residential buildings, 1st residential building design & construction conference – february 20-21, 2013 at sands casino resort, bethlehem, 2013; 284-293. a. morby. green light for world’s tallest modular tower in croydon. construction enquirer, 2017, available at: https://www.constructionenquirer. com/2017/12/04/green-light-for-worlds-tallestmodular-tower-in-croydon/ a. eagle. speed to market: hospitals tap modular construction to meet building demand, health facil manage, 2014; 27(5):18-23. b. sevenson. chinese unveil mysterious 3d printed house – built out of unique material, able to withstand devastating earthquakes, 3dprint.com, 2015, available at: https://3dprint.com/82322/chinese-3d-modular-homes/ d. lopez, t. froese. analysis of costs and benefits of panelized and modular prefabricated homes, procedia engineering, 2016; 145:1291-1297. https:// doi.org/10.1016/j.proeng.2016.04.166 e. m. generalova, v. p. generalov, a. a. kuznetsova. modular buildings in modern construction, procedia engineering, 2016; 153:167-172. https://doi. org/10.1016/j.proeng.2016.08.098 j. lee, m. park, h. lee, t. kim, s. kim, h. hyun. workflow dependency approach for modular building construction manufacturing process using dependency structure matrix (dsm), ksce journal of civil engineering, 2017; 21:1525-1535. https://doi. org/10.1007/s12205-016-1085-1 j. molavi, d. l. barral. a construction procurement method to achieve sustainability in modular construction, procedia engineering, 2016; 145:13621369. https://doi.org/10.1016/j.proeng.2016.04.201 j. zhang, y. long, s. lv, y. xiang. bim-enabled modular and industrializes construction in china, procedia engineering, 2016; 145:1456-1461. https://doi. org/10.1016/j.proeng.2016.04.183 m. kamali, k. hewage. development of performance criteria for sustainability evaluation of modular versus conventional construction methods, journal of cleaner production, 2017; 142:3592-3606. https://doi.org/10.1016/j.jclepro.2016.10.108 m. kamali, k. hewage. life cycle performance of modular buildings: a critical review. renewable and sustainable energy reviews, 2016; 62:1171-1183. https://doi.org/10.1016/j.rser.2016.05.031 m. larsson, a. kaiser, u. a. girhammar. multi-storey modular manoeuvres – innovative architectural stacking methodology based on three swedish timber building systems, auckland, new zealand 15-19 july 2012, world conference on timber engineering, 2012; 63-72. i. matei. ten fold and the mobile house of the future, urbanizehub, 2017, available at: http://urbanizehub.com/ten-fold-mobile-house-future/ o. mohsen, p. knytl, b. abdulaal, j. olearczyk, m. al-hussein. simulation of modular building construction, proceedings of the 20018 winter simulation conference, 2008; 2471-2478. https://doi. org/10.1109/wsc.2008.4736356 p. sharafi, m. mortazavi, b. samali, h. ronagh. interlocking system for enhancing the integrity of multi-storey modular buildings, automation in construction, 2018; 85:263-272. https://doi. org/10.1016/j.autcon.2017.10.023 r. e. smith. off-site construction implementation resource: off-site and modular construction explained, national institute of building sciences, 2016; 1-6. the modular building institute. improving construction efficiency & productivity with modular construction, 2010, available at: https://cdn.ymaws.com/www.nibs. org/resource/resmgr/oscc/osmc_explained.pdf t. ngo, r. crawford, p. mendis. embodied energy analysis of prefabricated reusable building modules for a multi-residential building, 47th anzses annual conference, 2009; 1-10. y. ding, e. deng, l. zong, x. m. dai, n. y. chen. cyclic tests on corrugated steel plate shear walls with openings in modularizes-construction, journal of constructional steel research, 2017; 138:675-691. https://doi.org/10.1016/j.jcsr.2017.08.019 julius endzelis master faculty of civil engineering and architecture main research area construction technology address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: julius.endzelis@gmail.com mindaugas daukšys dr. faculty of civil engineering and architecture main research area civil engineering, construction technology address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: mindaugas.dauksys@ktu.lt about the authors https://doi.org/10.1016/j.proeng.2016.04.166 https://doi.org/10.1016/j.proeng.2016.04.166 https://doi.org/10.1016/j.proeng.2016.08.098 https://doi.org/10.1016/j.proeng.2016.08.098 https://doi.org/10.1007/s12205-016-1085-1 https://doi.org/10.1007/s12205-016-1085-1 https://doi.org/10.1016/j.proeng.2016.04.201 https://doi.org/10.1016/j.proeng.2016.04.183 https://doi.org/10.1016/j.proeng.2016.04.183 https://doi.org/10.1016/j.jclepro.2016.10.108 https://doi.org/10.1016/j.rser.2016.05.031 https://doi.org/10.1109/wsc.2008.4736356 https://doi.org/10.1109/wsc.2008.4736356 https://doi.org/10.1016/j.autcon.2017.10.023 https://doi.org/10.1016/j.autcon.2017.10.023 https://doi.org/10.1016/j.jcsr.2017.08.019 46 darnioji architektūra ir statyba 2013. no. 2(3) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction the world is facing an unprecedented challenge to reduce emissions of greenhouse gases, such as co2, to limit global warming and climate change. cementitious materials, mainly concrete, have a big role to play in assuming a sustainable future. every year about 1.5 m3 (3 tonnes) is produced for every person on the planet and this success is due to the widespread availability of the raw materials, its low cost and flexibility (scrivener 2012). the reduction of energy consumption in construction and the solution of environmental problems by recycling of industrial and domestic waste is a relevant problem. recycling is an important environmental and economical alternative for each material class, mainly for those that do not decompose easily in nature, such as glasses – not decomposed by microbial nor by atmospheric precipitation for thousand years (delben et al. 2007). finely ground glass waste having a particle size finer than 38 μm have pozzolanic behaviour and concrete containing ground glass exhibits a higher strength at both the early and late ages compared to fly ash concrete (shao et al. 2000). sahayan and xu (2004) mentioned that fine glass powder could replace up to 30 % of portland cement. within last decade most of research was carried out on utilization of glass waste in concrete as fine and coarse aggregates, mostly on mechanical properties of concrete, but only little research was carried out on the investigation of thermal properties of cement paste with fluorescent lamp glass waste, glass cullet and coal/wood ashes patricija kara*, aleksandrs korjakins riga technical university, institute of materials and structures, chair of building materials and products, 1 kalku str., riga, lv-1658, latvia *corresponding author: patricija.kara@rtu.lv http://dx.doi.org/10.5755/j01.sace.2.3.2781 the thermal character of cement hydration reactions causes concrete to endure temperature changes during the first days after casting. the present research intends to evaluate the influence on the temperature of hydration of cement paste mixes with local industrial wastes such as lamp glass waste powder/suspension, glass cullet, bottom/fly coal/wood ashes substitution at level of 20% and 30%. the temperature of hydration of cement paste mixes was investigated by using specially designed equipment. the temperature of hydration inside of the cement paste specimens was continuously monitored at least up to 20 h after production at ambient air temperature 20±2°c. the results showed that cement paste substitution with lamp glass waste and coal/wood bottom ashes at level of 30% has influence on the peak temperatures of hydration with decrease from 58.8°c to 46.3°c and cement paste substitution with flint glass at level of 20% decrease temperature of hydration for around 19°c in comparison to control cement paste mix. keywords: thermal properties, fluorescent lamp glass waste, borosilicate lamp glass waste, glass cullet, ash. thermal properties of such concretes (poutos et al. 2008). topcu and canbaz (2004) concluded that when glass waste aggregates are used the workability of concrete is unaffected but the compressive, flexural and indirect tensile strength decrease in proportion to an increase in glass waste content. this finding is in general agreement with results obtained by park et al. (2004). improvements in cullet production methods were shown by sangha et al. (2004) to produce concrete which was stronger than that made with natural aggregate in tension and compression when cement was replaced with glass cullet at levels of 60 %. significantly higher temperatures were generated during hydration of concrete made with glass aggregates than with natural aggregates; this trend was more marked with green glass than concrete made with amber or clear glass (poutos et al. 2008). it was suggested by poutos that if concrete made with glass aggregates is used for construction, there may be potential for two important applications, namely, cold weather concreting and for buildings to maintain greater temperature stability. the hydration of a concrete mixture is a process that liberates heat and the rate of heat generation is accelerated with an increase in concrete temperature. concrete is a poor conductor of heat, and the rate of heat evolution due to the hydration process is, therefore, much greater than 47 the rate of heat dissipation. the development of high concrete temperatures causes a number of effects that show to be detrimental to long-term concrete performance. high concrete temperatures increase the rate of hydration, thermal stresses, the tendency for drying shrinkage cracking, permeability, and decrease long-term concrete strengths, and durability as a result of cracking. the higher the curing temperature is, the faster are the reactions between cement and water, and consequently the shorter becomes the setting time. spontaneous dissolution of cement begins in the initial or preparatory phase, immediately after its contact with water. small amounts of ettringite, calcium silicate hydrates (c-s-h) and calcium hydroxides (ch) are produced in the solid phase. this process lasts about 6 hours. in the second stage the formation of calcium silicate hydrate (c-s-h) continues. calcium aluminate trisulphate hydrate, the so-called ettringite (aft), forms during the reaction of aluminium compounds in clinker with gypsum. the highest concentration of this hydrate is reached at the end of the second phase. this phase lasts from the 6th until the 24th hour. the processes that occur after 24 hours of hydration are called crystallization stage. in this stage aft compounds react with the remaining clinker minerals and form calcium aluminate monosulpahte (afm) hydrates. c-s-h and ch content and crystal size increase. hydration of clinker minerals are exothermic reactions and therefore a certain amount of heat is released when cement is mixed with water. the biggest amount of heat is released during the hydration of c3a and c3s, whereas c2s reaction with water liberates very little heat (taylor 1997). heat liberation during cement curing has practical significance for concrete placing at low temperatures. on the other hand, big heat release has a negative impact in the manufacture of massive concrete structures. high temperature inside a massive structure and low temperature on the surface may cause the development of unfavorable stresses and cracking. specifications for temperature rise and differentials in massive pours require attention. a default peak temperature of 70°c is prudent as it would virtually eliminate the possible problem of delayed ettringite formation (def). while def is uncommon, it can cause enormous damage. many specifiers focus on the temperature differential within the concrete mass and a value of 20 °c is often specified. however, in my experience which is primarily in temperate and tropical zones, most thermal cracking has been caused by external restraint of massive concrete elements by a rigid substrate during cooling. the attention on the differential temperature requirement in temperate conditions often leads to excessive insulation and increases both the peak temperature and the volume of concrete that reached high temperature. therefore, to reduce a minor potential problem, the more likely problem is exacerbated. many specifications limit concrete placement temperature to 32 °c or less. in massive elements, very high replacement levels of fly ash and ggbs are extremely useful to limit temperature rise. the elevated temperature means that the in-situ maturity is high at relatively early ages so that acceptable strength and penetrability properties do not take long to develop. there are many situations where in-situ maturity monitoring can reduce unnecessary over-design of concrete mixes. an unnecessary impediment to sustainability and solving potentially serious thermal issues are the limits on supplementary cementing material replacement levels in many specifications. one does need to be cautious when using high replacement levels of fly ash in thin or suspended elements where the concrete could dry out and not develop the required properties. well-meaning specifications which extend the compliance testing age for concrete specifically to enable high replacement levels without considering insitu development of strength and other properties can be problematic (aldred, 2012). there is no information about influence of fluorescent lamp glass waste on the temperature of hydration in cement paste and concrete. therefore, in present study was investigated the influence of fluorescent lamp glass waste as cement component in cement paste mix on the temperature of hydration and for comparison were also investigated cement paste mixes substituted with bottom/fly ashes. 2. methods ordinary portland cement cem i 42.5n was applied as a binding agent. cement conforms to standard evs en 197-1:2002. sikament 56 polycarboxylates plasticizing agent was added to several cement paste mixes. borosilicate (drl) and fluorescent (lb) lamp glass waste powders that were obtained from lamp chippings were received from a local lamp recycling centre (kara et al. 2012). borosilicate glass is a type of glass with the main glass-forming constituents – silica and boron oxide. borosilicate glass has a very low thermal expansion coefficient (3.3 x 10−6/k), about one-third that of ordinary glass and less dense than ordinary glass. the addition of lead oxide to glass raises its refractive index and lowers its working temperature and viscosity. the presence of lead is used in glasses absorbing gamma radiation and x-rays, used in radiation shielding (e.g. in cathode ray tubes, where lowering the exposure of the viewer to soft x-rays is of concern). the high ionic radius of the pb2+ ion renders it highly immobile in the matrix and hinders the movement of other ions; lead glasses therefore have high electrical resistance, about two orders of magnitude higher than sodalime glass (108.5 vs 106.5 ohm·cm, dc at 250°c). leadcontaining glass is therefore frequently used in fluorescent light fixtures. the fineness of powders was obtained by the blaine apparatus testing bluhm&feuerherdt gmbh (50ml) using a method with the prior need to prior measure of density of the powder with a pyknometer in accordance with en 196-6. drl lamp chippings were ground for 30 and 60 minutes to a blaine fineness of 608 m2/kg and 746 m2/kg accordingly in laboratory planetary ball mill retsch pm400 (with rotation speed 300 min-1). lb lamp chippings were ground for 30 and 60 minutes to a blaine fineness of 542 m2/kg and 576 m2/kg accordingly. additionally, drl lamp chippings were also ground for 60 minutes in water environment with water/glass (160/90) weight proportion in order to obtain glass waste suspension and improve fineness of particles (kara, 2012). glass cullet was obtained from the beer bottles (green, 48 amber and flint colours) which were collected from the local glass bottle return point and manually crashed in the laboratory. green, amber and flint glass chippings were ground for 30 minutes to a blaine fineness of 460 m2/kg, 540 m2/kg and 500 m2/kg accordingly. coal and wood bottom ash were obtained from local sources in latvia. coal bottom ash (ca) and wood bottom ash (wa) were ground for 30 minutes to a blaine fineness of 849 m2/kg and 660 m2/kg accordingly. coal & wood fly ash (fa) with blaine fineness of 995 m2/kg was obtained outside from latvia. the chemical composition of drl, lb, coal/ wood bottom ashes and portland cement is given in the table 1. table 1. the chemical composition of lamp glass waste, bottom ashes and portland cement (kara 2013) bulk oxide, % mass drl lb wood ash coal ash pc cao 1.320 5.110 13.5 20.42 67.01 bao 1.63 2.362 0.13 0.21 0.04 al2o3 2.600 1,220 16.72 3.59 5.260 sio2 71.140 55.04 49.69 59.93 18.74 k2o 1.702 1.881 1.592 5.636 0.727 na2o 3.301 12.354 0.431 1.274 0.382 fe2o3 0.170 0.196 9.5 1.91 2.030 mno 0.006 0.011 0.193 0.469 0.059 mgo 0.615 2.946 5.132 3.505 1.812 tio2 0.006 0.027 0.84 0.193 0.261 so3 0.045 0.264 0.552 0.024 3.004 p2o5 0.023 0.038 0.865 1.723 0.151 b2o3 16,63 0 0 0 0 pbo 0 18.30 0 0 0 total 99.19 99.74 97.55 98.88 99.48 the experimental programme to measure the temperature of hydration of cement paste mixes with lamp glass waste, glass cullet and ashes was divided in two sets. first set of experiments for lamp glass waste and ashes was hold at vgtu using following equipment (fig. 1): cement paste mixes were cast in demountable 100·100·100 mm plywood moulds with a thermocouple (connected to a data transmitting device) polipropylene straw located in the center of one face of each mould. four moulds were placed separately into four metal boxes with 30 mm thick insulation layer of polystyrene foam. second set of experiments for glass cullet was hold at rtu using newly designed equipment with improved insulation, cement paste mixes were cast in demountable 150·150·150 mm plywood moulds with a thermocouple (connected to a data transmitting device) copper tube located in the center of one face of each mould. four moulds all together were placed into one plywood box with 50mm insulation layer of finnfoam (fig. 1). the temperature was continuously monitored at least up to 20 h after production at ambient air temperature 20 ± 1°c. fig. 1. equipment to measure hydration temperature inside of the concrete mixes: left at vgtu and right at rtu in total, 34 cement paste mixes were prepared (table 2). however, w/c ratio strongly influence the hydration process, the purpose of the investigation was also to maintain the similar workability of the mixes (kara 2013), therefore the w/c was not constant for all mixes. portland cement was substituted at level of 20 and 30 % with lamp glass waste. table 2. the cement paste compositions mix type grinding time, min cement replacement volume, % w/c ratio portland cement cem i 42,5 n, g lb powder glass,g drl powder glass,g drl glass suspension,g coal ash,g wood ash,g plasticizer, g water, g ctrl1 0 0 0.314 1000 ------314 lb1 30 20 0.314 800 200 -----314 lb2 30 30 0.314 700 300 -----314 drl1 30 20 0.314 800 -200 ----314 drls1 30 30 0.310 700 --400 ---ctrl2 0 0 0.273 1000 -----10 273 drl2 30 20 0.273 800 -200 ---10 273 lb3 30 20 0.273 800 200 ----10 273 ca1 30 30 0.285 700 ---300 --285 49 3. results fig. 2 illustrates the relationship between temperature and time during the first 20 hours of hydration for lb1, lb2, drl1, ctrl1 and drls1 mixes. the peak value of the temperature within the cement paste specimen was clearly defined and took place approximately 10 h after casting for all mixes. the highest temperature (67 ºc) achieved by ctrl1 occurred 9 h after casting. the generated temperatures during hydration of drl1 and lb1 mixes were almost equal to ctrl1. the highest rise of temperature (59ºc) for drls1 occurred 9 h after casting and showed lower result for almost 14 % in comparison to ctrl1. the highest rise of temperature (68.4 ºc) for drl1 occurred 10 h after casting, for lb1 occurred 10 h after casting with value of 67.8 ºc, for lb2 occurred 11 h after casting with value of 62.5 ºc. the temperature of hydration of lb2 was for 8 % lower than lb1. fig. 2. relationship between temperature and time during hydration for drl/lb glass waste powder and drl glass waste suspension cement paste mixes mix type grinding time, min cement replacement volume, % w/c ratio portland cement cem i 42,5 n, g lb powder glass,g drl powder glass,g drl glass suspension,g coal ash,g wood ash,g plasticizer, g water, g wa1 30 30 0.285 700 ----300 -285 cwa1 30 30 0.285 700 ---150 150 -285 fa1 0 30 0.360 700 fly ash: 300 360 ctrl3 0 0 0.285 1000 ------285 ca2 30 30 0.243 700 ---300 -10 243 wa2 30 30 0.243 700 ----300 10 243 ctrl4 0 0 0.243 1000 -----10 243 drlca1 30 30 0.261 700 300 --90 --285 lbca1 30 30 0.261 700 -300 -90 --285 drlwa1 30 30 0.261 700 300 ---90 -285 lbwa1 30 30 0.261 700 -300 --90 -285 drl3 60 30 0.285 700 300 -----285 lb4 60 30 0.285 700 -300 ----285 drls2 60 30 0.285 700 585.5 drllb1 60 30 0.285 700 150 150 ----285 drl4 60 30 0.273 700 300 ----10 273 lb5 60 30 0.273 700 -300 ---10 273 drllb2 60 30 0.230 700 150 150 ---10 230 ctrl5 0 0 0.285 3000 ------855 a1 30 20 0.285 2400 amber glass, 600 g 855 g1 30 20 0.285 2400 green glass, 600 g 855 f1 30 20 0.285 2400 flint glass, 600 g 855 a2 30 30 0.285 2100 amber glass, 900 g 855 g2 30 30 0.285 2100 green glass, 900 g 855 f2 30 30 0.285 2100 flint glass, 900 g 855 table 2 continuation. the cement paste compositions 50 fig. 3 illustrates the relationship between temperature and time during the first 40 hours of hydration for drl2, lb3 and ctrl2 mixes. the peak value of the temperature within the control cement paste specimen ctrl2 was clearly defined and took place approximately 17h after casting. the highest temperature achieved by ctrl2 was 79.4 ºc. fig. 3. relationship between temperature and time during hydration for drl and lb glass waste powder cement pastes with a plasticizing agent the peak values of the temperature within the drl2 and lb3 cement paste specimens were hindered and defined 23 h and 22 h after casting with values 63 ºc and 64 ºc correspondingly. fig. 4 illustrates the relationship between temperature and time during the first 20 hours of hydration for ca1, wa1, cwa1 and fa1 ash cement pastes and control cement paste ctrl3. the peak value of the temperature within the control cement paste specimen ctrl3 took place approximately 10 h after casting with value of 59 ºc. the generated temperatures during hydration of cement pastes made with bottom coal ash ca1 (53ºc) and bottom wood ash wa1 (55ºc) were lower in comparison to ctrl3. the cement paste with mixed wood and coal bottom ashes content showed lower peak value of 46.6 mºc which is 21 % lower than ctrl3 peak. the hydration of cement paste with coal/wood fly ash was hindered and peak was 16h after casting and was 52 mºc. fig. 4. relationship between temperature and time during hydration for ca, wa, cwa and fa ash cement pastes fig. 5 illustrates the relationship between temperature and time during the first 40 hours of hydration for ca2 and wa2 ash cement pastes with plasticizing agent, fa1 ash cement paste without plasticizing agent and control specimen ctrl4. the peak value of the temperature within the control cement paste specimen ctrl4 took place approximately 14 h after casting with value of 64 ºc. the generated temperatures during hydration of cement pastes made with bottom coal ash ca2 and bottom wood ash wa2 were lower in comparison to the control specimen ctrl4 with values of 52 m ºc and 50 m ºc correspondingly and hydration was also hindered for 10 hours in comparison to ctrl4. as it can be seen fa1 mix with the peak value of the temperature is reached almost by the same time as peak of ctrl4 and almost the same peak value of the temperature as for ca2 and wa2. the w/c ratio was higher for fa1 than for ca2 and wa2 due to the necessity of obtaining equal workability of the mixes. fig. 6 illustrates the relationship between temperature and time during the first 20 hours of hydration for drl and lb glass waste powder cement pastes with wa and ca ashes and control specimen ctrl3. as it was mentioned above the peak value of the temperature within the control cement paste specimen ctrl3 took place approximately 10h after casting with value of 59 ºc. it can be seen that hydration for all mixes was 12h after casting. addition of wa into the mix with lb glass waste lowered hydration temperature in comparison to control mix for almost 19 %. fig. 5. relationship between temperature and time during hydration for ca2 and wa2 ash cement pastes with a plasticizing agent, and fa1 ash cement paste without a plasticizing agent fig. 6. relationship between temperature and time during hydration for drl and lb glass waste powder cement pastes with wa and ca ashes 51 fig. 7 illustrates the relationship between temperature and time during the first 20 hours of hydration for drl3, lb4, drls2, drllb1 and ctrl3. it can be seen that hydration temperature peaks took place within 10–13h after casting; significant difference in peak values in comparison to all mixes shown at fig.6 was only for drllb1 with peak temperature of 46.3 °c which is lower for 21.5 % in comparison to ctrl3. significant workability of the mix drllb1 in comparison to other mixes with the same w/c ratio was observed. fig. 7. relationship between temperature and time during hydration for drl and lb glass waste powder/drl glass waste suspension cement pastes ground for 60 minutes fig. 8 illustrates the relationship between temperature and time during the first 40 hours of hydration for drl4, lb5, drllb2 and ctrl2. it can be seen that hydration peaks for mixes drl4, lb5, drllb2 took place within 20–25 h after casting and were also hindered for 9 hours in comparison to ctrl4. drllb2 had lower w/c ratio due to very good workability and equal temperature of hydration with drl4. the best value of temperature of hydration was for mix lb5 (49.6 °c). fig. 9 illustrates the relationship between temperature and time during the first 20 hours of hydration for ctrl5, a1, g1 and f1. it can be seen that hydration temperature peaks for ctrl5 took place within 8h after casting with highest value of 93.6 °c. fig. 8. relationship between temperature and time during hydration for drl and lb glass waste powder/drl glass waste suspension cement pastes ground for 60 minutes with a plasticizing agent fig. 9. relationship between temperature and time during hydration for amber, green and flint glass waste powder cement pastes ground for 30 minutes the hydration process of glass cullet cement pastes with 20 % cement substitution was hindered for 5 hours in comparison to ctrl5 (fig. 9). the highest value of the hydration temperature was for amber glass – 83,9 °c and the lowest for flint glass – 74,4 °c. cement substitution with glass cullet at level of 30 % didn’t show so big difference for temperature of hydration among the amber, green and flint glass in comparison to cement substitution with 20 % (fig. 10). as it can be seen the hydration peaks have same values around 80 °c which are lower for about 14 °c in comparison to control mix ctrl5. fig. 10. relationship between temperature and time during hydration for amber, green and flint glass waste powder cement pastes ground for 30 minutes 4. discussion the highest temperature rise and the greatest heat loss in cement paste occur during the first day of curing. afterwards the transfer of heat slows down considerably and temperature rise in cement paste is insignificant. in the present study the maximum temperature during first day in cement paste was 68.4 °c at ambient air temperature 20±1 °c, which is rather high and therefore portland cement is not recommended for placing concrete in massive structures, for example. properties like workability and temperature of hydration are developed through pozzolanic reaction between amorphous silica in the supplementary cementitious materials and portlandite, (ca(oh)2), released during cement hydration and formation of insoluble calcium 52 silicate hydrates (c–s–h) (cook, 1986). the lamp glass waste and bottom ashes react pozzolanic to calcium silicate hydrates (c-s-h) and calcium aluminate hydrates (c-a-h), and due to alkaline activation to aluminosilicate gels. the pozzolanic reaction of them is influenced by the reactivity and the interaction of different elements such as si, al, the alkalis and others. particle size is influential in controlling the mechanism of pozzolanic reactions. the hydration of cement paste mix produces ca(oh)2 and it is consumed during pozzolanic reaction. mixes composed of particles whose size is the smallest and surface area is the largest have the largest consumption of ca(oh)2. dyer and dhir (2001) concluded that increased ca(oh)2 levels observed in glassbearing blends may be a result of glass constituents being incorporated into c–s–h in the place of ca from the cement powder, resulting in excess ca(oh)2 the pore solution. it was observed that the cement substitution at level of 30 % with glass waste ground for 60 minutes significantly influences on the workability of the mixes with low water absorption in comparison to the mixes with bottom ashes. portland cement with substitution at level 30 % with glass waste powder ground for 30 minutes showed slightly lower results in range of 2–3 °c difference in comparison to portland cement control mix, and as far as glass waste was additionally was ground for 60 minutes in dry/water environment the peak temperatures were already lower up to 59 °c and for lb glass even 53 °c. the lowest peak temperature 46.3°c was for mix with drl & lb glass waste (drllb1) and similar to the peak temperature 46.6 °c of mix cwa1 with coal & wood bottom ashes. somehow, mixes with two waste products like drl & lb or ca & wa showed lower temperature peaks of hydration and performed better workability. it could be explained by the chemical composition of the combined waste materials. it was observed that the hydration temperature rises when cement substitution with green and flint glass increased up to 30 %, except amber glass when temperature went down. therefore, the optimal cement substitution with green and flint glass is at level of 20 % with significant temperature of hydration for flint glass. it was observed that a plasticizing agent had slight effect on the temperature decrease in the range of 3–4 °c. 5. conclusions lamp glass waste, glass cullet and ashes have significant influence on the temperature of hydration in cement paste. lower temperatures are generated during hydration of cement pastes (w/c = 0.285) substituted with lamp glass waste and bottom ash at level of 30 %, and flint glass – at level of 20 %. the temperature decrease from 58.8 °c to 46.3 °c is observed for cement paste mixes with lamp glass waste (drllb1) and from 58.8 °c to 46.6 °c for mixes with bottom ash (cwa1), and for flint glass from 93.6 °c to 74.4 °c. the cement paste mixes with glass waste ground for 60 minutes, flint glass ground for 30 minutes perform better workability, low water absorption in comparison to the mixes with bottom ash. it can be concluded that the temperature rise declines as the quality of lamp glass waste improves: as finer are lamp glass waste particles (blaine fineness above 600 kg/m2), less water is required to achieve the desired mix workability, lower is temperature of hydration of cement paste and higher is compressive strength. acknowledgment the financial support of the eraf project nr. 2010/ 0286/2dp/2.1.1.1.0/10/apia/viaa/033 „high efficiency nanoconcretes” is acknowledged. the authors gratefully acknowledge the help of the vgtu civil engineering centre and scientific institute of thermal insulation in providing the laboratory equipment to determine temperature of hydration of cement paste mixes and blaine fineness in the present investigation. references aldred, j. 2012. removing impediments to the more sustainable use of concrete. in: proceedings of 8th international conference: concrete in the low carbon era 2012, dundee, uk, 17–32. cook dj. 1986. natural pozzolans. cement replacement materials, vol. 3. london, surrey university press, 1–39. delben, a. a. s. t., menezes, delben, f. l., j. r., coelho, m. b., ribeiro, r. f. 2007. effect of glass cullet on thermal properties of kaolinite. journal of thermal analysis and calorimetry, vol. 87(3), 879–882. http://dx.doi.org/10.1007/s10973-006-7681-4 dyer td, dhir rk. 2001. chemical reactions of glass cullet used as cement component. journal of materials in civil engineering, vol. 13, no. 6, 412–417. ] http://dx.doi.org/10.1061/(asce)0899-1561(2001)13:6(412) kara, p., korjakins, a. 2012. concrete with fluorescent waste glass suspension. in: proceedings of 8th international conference: concrete in the low carbon era 2012, dundee, uk, 719– 728. kara, p., korjakins, a., shakhmenko, g., 2012. high efficiency nanoconcrete containing local industrial by-products and wastes, abstract book of 17th international conference on mechanics of composite materials, jurmala, latvia, pp. 11. kara, p., korjakins, a., kovalenko, k. 2012. the usage of fluorescent waste glass powder in concrete. scientific journal of riga technical university, construction science, vol. 13, 26–32. http://dx.doi.org/10.2478/v10311-012-0004-z kara, p., korjakins, a., stokmanis-blaus, v. 2012. evaluation of properties of concrete incorporating ash as mineral admixtures. scientific journal of riga technical university, construction science, vol. 13, 17–25. http://dx.doi.org/10.2478/v10311-012-0003-0 kara p., 2013. rheological and strength performance of cement paste with ground fluorescent lamp glass waste and ash. in: proceedings of international conference: civil engineering 13’, jelgava, latvia. park sb, lee bc, kim jh. 2004. studies on mechanical properties of concrete containing waste glass aggregate. cement and concrete research, vol. 34(12), 2181–2189. http://dx.doi.org/10.1016/j.cemconres.2004.02.006 53 poutos k. h., alani a. m., walden p. j., sangha c. m. 2008. relative temperature changes within concrete made with recycled glass aggregate. construction and building materials, vol. 22, 557–565. http://dx.doi.org/10.1016/j.conbuildmat.2006.11.018 sangha cm, alani am, walden pj. 2004. relative strength of green glass cullet concrete. magazine of concrete research, vol. 56(5), 293–297. http://dx.doi.org/10.1680/macr.2004.56.5.293 sahayan a, xu a. 2004. value-added utilization of waste glass in concrete. cement and concrete research, vol. 34, 81–89. http://dx.doi.org/10.1016/s0008-8846(03)00251-5 shao y., lefort t., moras s., rodriguez d. 2000. studies on concrete containing ground waste glass. cement and concrete research 30, 91–100. http://dx.doi.org/10.1016/s0008-8846(99)00213-6 skrivener, k. 2012. nanoscience for sustainable cementitious materials. proceedings of 40th ict convention/symposium 22nd march 2012, 27–34. taylor, h. f. w. 1997. cement chemistry, 2nd edition, thomas telford, london, isbn 0727725920, vol. 2, p. 459. http://dx.doi.org/10.1680/cc.25929 topcu ib, canbaz m. 2004. properties of concrete containing waste glass. cement and concrete research, 34(2), 267–74. http://dx.doi.org/10.1016/j.cemconres.2003.07.003 received 2012 11 7 accepted after revision 2013 03 18 patricija kara – scientific researcher, lecturer at riga technical university, institute of materials and structures, chair of building materials and products. member of lvs stk 30 eurocode sub-committee. main research area: concrete technology, recycling of industrial wastes and by-products in concrete, environmental management, eco-construction materials. address: 1 kalku str., riga lv-1658, latvia. tel.: +37167089243 e-mail: patricija.kara@rtu.lv aleksandrs korjakins – professor at riga technical university, institute of materials and structures, head of chair of building materials and products. main research area: building materials and structures, ecological building materials, reuse of industrial waste. address: 1 kalku str., riga lv-1658, latvia. tel.: +37167089248 e-mail: aleksandrs.korjakins@rtu.lv 121 journal of sustainable architecture and civil engineering 2021/2/29 *corresponding author: rami-hamad@hotmail.com; rami@icem.edu.om critical factors affecting the success of construction projects in oman received 2021/06/12 accepted after revision 2021/09/14 critical factors affecting the success of construction projects in oman jsace 2/29 http://dx.doi.org/10.5755/j01.sace.29.2.29269 rami j.a. hamad* international college of engineering and management, p.o. box 2511, c.p.o seeb, p.c. 111, oman bassam a. tayeh civil engineering department, islamic university of gaza, p.o. box 108, gaza strip, palestine hamdan a. al aisri arabian industry projects, muscat, oman journal of sustainable architecture and civil engineering vol. 2 / no. 29 / 2021 pp. 121-138 doi 10.5755/j01.sace.29.2.29269 introduction construction in oman is an important sector that contributes greatly to the country’s economic growth. recently, the construction projects in oman have been delayed which has led to delays in the projects’ completion and sometimes to their failure. this study aims to examine the critical factors affecting the success of construction projects in oman. the extent to which factors related to project parties affect this success was assessed. a quantitative approach based on systematic literature review and questionnaire survey technique was used. the factors were identified and classified into six main categories, namely, time; finance; project designing, planning and scheduling; quality; project progress and development; and environment and nature. the factors are also classified as client-, consultant-, contractorand externalrelated factors. this study was conducted by distributing questionnaires to people who experienced working in the public and private construction sectors in oman. relative importance index method was used for analysis. results show that quality is the most important amongst the six investigated categories, followed by time; finance; project progress and development; project designing, planning and scheduling; and environment and nature. the client-related factors have the highest impact on the success of construction projects in oman, followed by consultant-, contractorand external environment-related factors. the selection of a low bid, rather than accurate and reliable bids, and the quality and experience of the project team and labour are the most significant factors affecting the success of construction projects in oman. the contractors’ administrative corruption, indiscipline and dishonesty and the frequent equipment breakdowns are the two least important factors affecting the success of construction projects. the government should encourage clients to improve their procurement strategies and force the construction companies to implement innovative approaches to project delivery. keywords: construction orojects, critical success factors, oman, project success, relative importance index. the construction industry is important in the economy of countries (chan et al., 2004; el-hallaq & tayeh, 2016). the different types of construction projects include buildings, roads and bridges. oman’s construction sector has grown from us$ 4.9 billion in 2013 to us$ 5.2 billion in 2014 and is estimated to reach us$ 5.6 billion in 2015 (mordor intelligence, 2017). the omani government’s ninth five-year development plan 2016–2020 and the oman vision 2020 support the growth in the construction industry by focusing on investments in transport infrastructure (e.g. seaports, railway lines and airports), utility facilities, affordable housing and special economic zones (global data, 2017; building and construction authority singapore, 2017). under the ninth five-year development plan 2016–2020, the government is investing omr 66.0 billion (us$ 171.7 billion) until 2020 to develjournal of sustainable architecture and civil engineering 2021/2/29 122 op the overall infrastructures (global data, 2018). in addition, the omani government aims to attract foreign investments by simplifying the relevant rules and regulations (mordor intelligence, 2017). project success has no accepted universal definition (nguye & chovichien, 2013). the definition of the success of construction projects varies amongst stakeholders. a project is considered successful if the objectives and expectations are achieved. these objectives and expectations may include different issues, such as technical, financial, educational, social and professional issues (parfitt & sanvido, 1993). in the 1980s, a construction project is considered successful if it is completed within the specified time, budget and required standard of quality in addition to customers’ satisfaction (khosravi & afshari, 2011). the success of a construction project is measured using two categories: small and large viewpoints. the former is measured by time, cost and quality of completion in addition to the completion performance and safety; the latter is assessed by completion time, stakeholders’ satisfaction and completion facilities and operation (lim & mohamed, 1999; abu aisheh et al., 2021). however, defining project success has remained unclear for construction professionals; thus, numerous studies on the critical factors affecting the success of construction projects have been conducted in the past years (chan et al., 2004; wang & huang, 2006; ramlee et al., 2016; das & ngacho, 2017; tayeh et al., 2018). different critical success factors (csfs), such as safety, quality, time and scheduling, planning, resources, cost and finance, technology, environment, organisation, management, experience, size and type of previous projects, have been defined by several researchers; however, no general agreement has been identified (belassi & tukel, 1996; ramlee et al., 2016; alzahrani & emsley, 2013; babu & sudhakar, 2015; maliha et al. 2021). chan et al. (2004) classified csfs into five categories: project-related, project procedures, project management actions, human-related and external environmental factors. babu (2015) categorised csfs into 10 main groups: cost, time, quality, productivity, client satisfaction, community, people, health and safety, innovation and learning and environmental factors. ramlee et al. (2016) summarised the csfs identified by several researchers to include cost, time, quality, satisfaction, management, safety, technology, organisation, environment and resources. all researchers have agreed that cost, time and quality are important csfs, whereas 50% of these researchers have considered management, technology, organisation and satisfaction as important csfs. babu and sudhakar (2015) summarised the most important csfs within the project life cycle as clarity of project objectives, top management support, efficiency of project manager, efficiency of project team members, detailed plan of the project activities or schedule, effective communication between client and project team members, quality of suppliers and subcontractors, client approvals, monitoring and feedback, suitable technology and communication network and troubleshooting of unexpected crisis and problems. kylindri et al. (2012) summarised the specific success dimensions identified by other researchers and found that cost, time, quality, efficiency, performance and technical success factors have been excessively researched. other factors, such as client satisfaction, safety, team creativity, knowledge and project management process, must be further explored. al-tmeemy & harun (2011) and raphael (2016) defined a construction project as successful if it satisfies the specified completion time, total cost, agreed technical specifications of the project and clients’ and customers’ expectations. these project success measures depend on various factors, such as client, contractor, project team, nature of the project, location and size of the project, technology to be used, contract type and risks involved (tayeh et al., 2020c). abdul-rahman et al. (2011) identified the possible causes of financial-related problems that contribute to project delays and found that the instability of the contractor’s financial background, the unavailability of a project financer and poor cash flow management are major factors contribute to project delays. a well-managed cash flow improves the time performance of the project; con123 journal of sustainable architecture and civil engineering 2021/2/29 versely, poor cash flow leads to project failure (abdul-rahman et al., 2011). tanzi and davoodi (1998) and gillanders (2014) stated that countries with high corruption rate have worse infrastructures than other countries. tayeh et al. (2018) confirmed that the availability of funding and regularity of payments affect the project’s progress and success considerably. abdul-rahman et al. (2009) revealed that project delay depends greatly on the client’s poor financial management and difficulties in obtaining funding from financers. homthong and moungnoi (2016) stated that clients should pay contractors on time to eliminate any delay in the project. yong and mustaffa (2012) determined that the client’s financial capability and delay of progress payments are the two top client-related factors affecting the construction projects in malaysia. the contractor’s unstable financial situation and inability to perform the work and pay salaries, subcontractors and other expenses affect the project progress negatively and thus lead to project failure (tayeh et al., 2018). oyewobi et al. (2015) stated that variations during construction are time consuming and costly because they increase construction costs and time by 34% and 29.5%, respectively. these variations also increase project rework and demolition and thus lead to client dissatisfaction and project failure. frequent equipment breakdowns in construction sites are a common problem that increases the downtime and requires costly repair (tsado & theophilus, 2014). chan et al. (2004( and akanni et al. (2015) reported that the external factors that affect the construction projects include economic, social, political, physical, industrial, legal, cultural and technological factors. physical factors include climatic condition, weather, natural disaster (e.g. storm, fire and landslide) and unexpected geological conditions. akanni et al. (2015) found that climatic condition and weather factors are the most important amongst all 29 external factors investigated. fong and choi (2000) stated that the selection process of reliable bids is critical for clients who are seeking for successful projects. this process must not be based on underor overweighed quality, time and cost criteria. muhwezi et al. (2014) identified the csfs related to clients and arranged them in the following order: corruption, poor cash flow, change orders, delay in payments and changes in materials and design. yong and mustaffa (2012) reported that the client’s excessive variations during construction are the third most important factor that affects the construction projects in malaysia. tayeh et al. (2018) emphasised the importance of the time of the design stage for the successful implementation of projects. delays during the design stage lead to an overall delay in the work and thus affect the success of the project. muhwezi et al. (2014) ranked the client’s delay in approving design documents as the sixth top client-related factor. tayeh et al. (2018) observed that the quality and experience of the design team considerably affect the quality and outcomes of the project. homthong and moungnoi (2016) determined that the adequate experience of project participants is the second highest critical affecting factor of the success of a project because successful projects require an experienced team to execute the work. muhwezi et al. (2014) identified the csfs related to contractors and arranged them in the following order: dishonesty, inadequate contractor experience, incompetent project manager, inappropriate construction methods and poor site management. tayeh et al. (2018) stated that the contractor’s experience in performing the work is the highest contractor-related affecting factor of construction project success. yong and mustaffa (2012) determined that the quality of subcontractors and skills of workers are two top contractor-related factors affecting the success of construction projects in malaysia. homthong and moungnoi (2016) suggested that the availability of skilled and experienced personnel is the second highest human resource-related affecting factor of project operations and progress. the external factors that affect construction projects are economic, social, political, physical, industrial, legal, cultural and technological factors. muhwezi et al. (2014) stated that identifying the occurrence of external factors and controlling them are difficult because these factors originate from sources outside the project. abdul-rahman et al. (2009) confirmed that financial market instability, journal of sustainable architecture and civil engineering 2021/2/29 124 including inflation of material prices, wages and transportation cost, significantly affects cash flow and leads to project delays. yong & mustaffa (2012) reported that the weather condition factor is the least significant amongst 15 critical factors affecting the success of construction projects in malaysia. al harthi (2005) investigated the effect of variation orders in construction projects in oman. it was found that costly and time-consuming variation orders appear during construction work and are considered the primary causes of delays and disputes; thus, serious cost impacts and project failure occur. oyegoke and al kiyumi (2017) identified the most important factors affecting the success of mega construction projects in oman; these factors include selecting the lowest price tendering, rather than the optimal value tender; the financial situation of the main contractor; delay in decision making by clients; poor contractor planning; and cost and time overruns in projects. al maktoumi et al. (2020) studied the causes of the delays in construction project in oman and investigated the effects of such delays. it was found that the delay of construction project completion in oman was mainly due to client-related factors followed by equipment-related factors, and material related factors. the client’s delay in providing the contractors with the necessary facilities, equipment and sufficient time and the delay in making decisions are the most important factors affecting the construction project progress in oman. al adawi et al. (2020) studied the impact of governmental stakeholders on the progress of projects in oman. it was found that governmental authorities, through lengthy approval processes, have a crucial effect on delaying the projects completion and hence lead projects to fail. the approval process in oman is very slow, and the average duration needed for obtaining a single approval from governmental authorities is two to four weeks. although building information modeling (bim) technology is not new to the construction industry, limited research on bim implementation had been conducted in developing countries, such as gcc countries. results of the few research studies conducted in ksa, uae, turkey and iraq revealed that most of the construction companies lack knowledge and awareness of building information modeling (bim) technology. the implementation of bim technology in construction projects is still at slow rate in the middle east, especially in sultanate of oman (darwish et al.; 2020; al-ashmori et al., 2020; umar, 2021). only 20% of construction companies in middle east are using bim in their projects (gerges et al., 2017). due to the lack of knowledge and implementation of bim, the authors did not consider the implementation of bim technology as a critical factor affecting the success of construction projects in oman. limited works have been conducted to analyse the success of construction projects in oman and define the critical factors affecting the success of the omani construction industry (oyegoke and al kiyumi, 2017; al maktoumi et al., 2020). there are contradictions in the research results and lack of common agreement amongst researchers on the critical factors affecting the construction projects. it is evident that there is a high need to conduct more research studies to investigate the main factors which lead to success or failure of construction projects in the sultanate of oman. additional studies should be conducted to examine the impact of these factors on the omani economy for improving the efficiency of construction projects in oman. in the present study, the critical success factors affecting the success of construction projects in oman and their impact on the omani construction sector are investigated using a quantitative approach based on systematic literature review and questionnaire survey technique. the criteria to measure the success of a project are evaluated in terms of time and scheduling, finance and cost, design and planning, quality, progress and productivity, and environment. the extent to which factors related to clients, consultant, contractor and external environment affect the success of construction projects in oman is also assessed. table 1 summarizes the critical factors used in the current study with their references from the previous studies. according to the literature review, the studied factors were classified into four broad categories, namely, client-, consultant-, contractorand external-related factors. 125 journal of sustainable architecture and civil engineering 2021/2/29 table 1 factors used in the questionnaire category factors related to factors references time client client delay in decision-making oyegoke & al kiyumi, 2017; das & ngacho, 2017; al maktoumi et al.,2020. client client delay in payments abdul-rahman et al., 2009; abdulrahman et al., 2011. client delay in providing temporary utilities of water, electricity, and a/c for construction site tayeh et al., 2018; al adawi et al., 2020; al maktoumi et al.,2020. client/ consultant delay in design (drawings) approval. muhwezi et al., 2014; tayeh et al., 2016; das& ngacho, 2017; oyegoke & al kiyumi, 2017. client/ consultant delay in approving materials babu, 2015; tayeh et al., 2016; das & ngacho, 2017. contractor project manager delay in making and issuing decisions babu, 2015; das & ngacho, 2017; contractor unrealistic project timelines oyegoke & al kiyumi, 2017; das & ngacho, 2017; al maktoumi et al.,2020. contractor shortage and delay in material supply akanni et al., 2015; al maktoumi et al.,2020. external delay in issuing approvals by authorities tayeh et al., 2016; al adawi et al., 2020. finance client lack of project financing abdul-rahman et al., 2009; abdulrahman et al., 2011. client/ contractor poor cash flow (irregular cash flow) abdul-rahman et al., 2009; abdulrahman et al., 2011; albhaisi, 2016. client/ contractor/ consultant financial corruption abdul-rahman et al., 2009; abdulrahman et al., 2011; gillanders, 2014; albhaisi, 2016. contractor contractor’s unstable financial situation abdul-rahman et al., 2009; abdulrahman et al., 2011; alzahrani & emsley, 2013; tayeh et al., 2016. external poor economic conditions abdul-rahman et al., 2009; abdulrahman et al., 2011. external inflation (material prices, labor, and transportation costs) abdul-rahman et al., 2009; abdulrahman et al., 2011; akanni et al., 2015. project designing, planning and scheduling client inadequate information provided by a client during feasibility studies chan et al., 2004; babu & sudhakar, 2015; das & ngacho, 2017; tayeh et al., 2017; al maktoumi et al.,2020. consultant misunderstanding of owner requirement and project objectives muhwezi et al., 2014; homthong & moungnoi, 2016; das & ngacho, 2017; tayeh et al., 2018; tayeh et al., 2019. consultant insufficient data collection and survey prior to design muhwezi et al., 2014; babu & sudhakar, 2015; das & ngacho, 2017; tayeh et al., 2018. consultant errors in design and failure to satisfy design objectives muhwezi et al., 2014; babu & sudhakar, 2015; babu, 2015. contractor ineffective project planning and schedule al-tmeemy & harun, 2011; das & ngacho, 2017; oyegoke & al kiyumi, 2017. journal of sustainable architecture and civil engineering 2021/2/29 126 category factors related to factors references quality client selection of a low bid, rather than an accurate and reliable bid fong & choi, 2000; chan et al., 2004; meland et al., 2011; oyegoke & al kiyumi, 2017. contractor/ consultant unqualified/inadequate experienced labor and team muhwezi et al., 2014; babu, 2015; das & ngacho, 2017; al maktoumi et al.,2020. contractor incompetent project manager babu & sudhakar, 2015; babu, 2015; tayeh et al., 2020a. contractor unqualified suppliers al maktoumi et al., 2020; alzahrani & emsley, 2013. contractor unqualified sub-contractors das & ngacho, 2017; al maktoumi et al., 2020. contractor poor quality of materials homthong & moungnoi, 2016; al maktoumi et al., 2020; tayeh et al., 2020b. project progress and development client design changes and variations during construction work al harty, 2005; oyewobi et al.,2016; das & ngacho, 2017; al maktoumi et al., 2020. client lack of incentives for contractors to follow project schedule chan et al., 2004; chen et al., 2021. client/ consultant/ contractor poor communication and coordination with other project parties chan et al., 2004; wang & huang, 2206; babu & sudhakar, 2015; homthong & moungnoi, 2016; das & ngacho, 2017; nguye & chovichien, 2013; tayeh et al., 2018; malik et al.,2021. consultant inadequate project management assistance al-tmeemy & harun, 2011; babu & sudhakar, 2015. consultant poor supervision of consultant to contractor activities chan et al., 2004; homthong & moungnoi, 2016. contractor poor site management and supervision by a project manager belassi & tukel, 1996; homthong & moungnoi, 2016. contractor poor risk management and inappropriate handling of unexpected problems and crises alzahrani & emsley, 2013; homthong & moungnoi, 2016. contractor inadequate implementation of health and safety procedures chan et al., 2004; homthong & moungnoi, 2016; tayeh et al., 2018; mahfuth et al.,2019. contractor lack of materials akanni et al., 2015; al maktoumi et al.,2020. contractor frequent equipment breakdowns tsado & theophilus, 2014; homthong & moungnoi, 2016; al maktoumi et al.,2020. contractor administrative corruption, indiscipline, and dishonesty alzahrani & emsley, 2013; gillanders, 2014; muhwezi et al., 2014. contractor shortage of labor and equipment belassi & tukel, 1996; akanni et al., 2015; al maktoumi et al., 2020. environment external emergence of natural factors, such as rainstorms, windstorms, and floods akanni et al., 2015; das & ngacho, 2017; tayeh et al., 2018. 127 journal of sustainable architecture and civil engineering 2021/2/29 date collection method quantitative research is usually conducted to quantify a problem by creating numerical data or data that can be converted into applicable statistics (fellows & liu, 1997). in this study, a quantitative approach was used as the main method to obtain appropriate and accurate data. data collection was conducted by distributing questionnaires to people who have a long work experience in the public and private construction sectors in oman. data analysis was conducted using relative importance index method. these respondents were clients, sponsors, project managers, project team members, contractors and people involved in the project implementation. the questions in the questionnaires were formulated based on the data collected from the literature review and interviews conducted with key people in the construction industry. the critical factors used in designing the questionnaire are summarized in table 1. the studied factors are classified into four broad categories, namely, client-, consultant-, contractorand external-related factors. research location and duration this study was conducted in muscat governorate during two different periods from october 2017 to march 2018 and from january to april 2021. sample size and population one hundred fifty questionnaires were distributed. the total number of the collected questionnaires was 77, which represents 51% of the total distributed copies. the number and classification of the respondents were 17 client representatives, 23 contracting engineers, 10 project managers, 23 architects and consulting engineers and 4 site supervisors. the respondents had 5–28 years of experience in the construction industry. questionnaire design the questionnaires were designed on the basis of the objectives of the study, literature review outcomes and personal interviews with experts in the omani construction sector. the questionnaire has 43 questions, which were divided into two main groups, namely, general and specific questions. general questions include multiple-choice questions about personal and organisational information (four items). subject-related specific questions include five-point likert scale questions, which measure the level of agreement of respondents on the proposed factors of project success. the levels of agreement used were presented as follows: 1 = strongly disagree, 2 = disagree, 3 = neither agree nor disagree, 4 = agree and 5 = strongly agree. a total of 39 factors affecting the success of construction projects were identified and divided into the following main categories. methodology _ time _ finance _ project designing, planning and scheduling _ quality _ project progress and development _ environment and nature data analysis the contribution and ranking of each of the factors as perceived by the respondents are analysed using relative importance index (rii) method (muhwezi et al., 2014). equation (1) is used to calculate the rii, and the results are summarised in table 2. 8 iii. project designing, planning and scheduling iv. quality v. project progress and development vi. environment and nature data analysis the contribution and ranking of each of the factors as perceived by the respondents are analysed using relative importance index (rii) method (muhwezi et al., 2014). equation (1) is used to calculate the rii, and the results are summarised in table 2. 𝑅𝑅𝑅𝑅𝑅𝑅 = ∑𝑊𝑊𝐴𝐴. 𝑁𝑁 , (1) where w – weight given to each factor by the respondents and ranges from 1 to 5 a – highest response weight (5) n – total number of respondents study limitation the first limitation of the current study is the relatively small number of respondents. although there are significant conclusions made based on the responses obtained from the survey respondents, the findings may not accurately reflect the opinion of the entire professionals in the omani construction sector. secondly, this study was conducted in the muscat governorate and all questionnaires were distributed amongst professionals who are working in muscat. the limitations identified by this study suggest that further studies should be conducted targeting the construction professionals who are working in cities other than muscat to increase the sample size and maximise the accuracy of the current results. 3. results and discussion 3.1. general information of the respondents the respondent sample includes 17 client representatives, 27 contracting engineers and supervisors, 10 projects managers and 23 consulting architects/engineers. a total of 58% of the respondents work in various government construction projects, whereas 42% of them work in private construction projects. a total of 27, 23, 19, 5 and 3 of the respondents have total years of experience of 1–5, 6–10, 11–15, 16–20 and above 20 years, respectively. therefore, the respondents are adequately qualified to answer the distributed set of questions. table 2 rii, mean score and rank for all factors used in the study. category factors related to factors rank mean score std. dev. rii time external delay in issuing approvals by authorities. 1 3.51 1.02 0.702 client consultant delay in design (drawings) approval 2 3.41 1.19 0.682 client client delay in payments. 3 3.38 0.98 0.676 client client delay in decision-making. 4 3.35 0.98 0.670 client consultant delay in approving materials. 5 3.32 1.23 0.664 contractor delay and shortage in material supply. 6 3.32 1.08 0.664 contractor unrealistic project timelines. 7 3.24 1.14 0.648 client delay in providing temporary utilities of water, electricity, and a/c for construction site. 8 3.11 1.26 0.622 (1) where w – weight given to each factor by the respondents and ranges from 1 to 5 a – highest response weight (5) n – total number of respondents journal of sustainable architecture and civil engineering 2021/2/29 128 table 2 rii, mean score and rank for all factors used in the study category factors related to factors rank mean score std. dev. rii time external delay in issuing approvals by authorities. 1 3.51 1.02 0.702 client consultant delay in design (drawings) approval 2 3.41 1.19 0.682 client client delay in payments. 3 3.38 0.98 0.676 client client delay in decision-making. 4 3.35 0.98 0.670 client consultant delay in approving materials. 5 3.32 1.23 0.664 contractor delay and shortage in material supply. 6 3.32 1.08 0.664 contractor unrealistic project timelines. 7 3.24 1.14 0.648 client delay in providing temporary utilities of water, electricity, and a/c for construction site. 8 3.11 1.26 0.622 contractor project manager delay in making and issuing decisions. 9 3.05 1.08 0.610 overall 3.30 0.660 finance contractor contractor’s unstable financial situation. 1 3.41 1.21 0.682 client lack of project financing. 2 3.35 1.32 0.670 external inflation (material prices, labor, and transportation costs). 3 3.19 1.17 0.638 client contractor consultant financial corruption. 4 3.00 1.53 0.600 external poor economic conditions. 5 2.95 1.29 0.590 client contractor poor cash flow (irregular cash flow). 6 2.95 1.10 0.590 overall 3.14 0.628 project designing, planning and scheduling client inadequate information provided by a client during feasibility studies. 1 3.19 1.22 0.638 consultant errors in design and failure to satisfy design objectives. 2 3.08 1.19 0.616 consultant insufficient data collection and survey prior to design. 3 3.00 1.33 0.600 contractor ineffective project planning and schedule. 4 2.92 1.38 0.584 consultant misunderstanding of owner requirement and project objectives. 5 2.84 1.30 0.568 overall 3.01 0.601 quality client selection of a low bid, rather than an accurate and reliable bid 1 3.65 1.46 0.730 contractor consultant unqualified/ inadequate experienced labor and team 2 3.65 1.25 0.730 contractor unqualified sub-contractors 3 3.54 1.02 0.708 contractor unqualified suppliers 4 3.46 1.30 0.692 contractor poor quality of materials 5 3.19 1.13 0.638 contractor incompetent project manager 6 2.86 1.25 0.572 overall 3.39 0.678 129 journal of sustainable architecture and civil engineering 2021/2/29 study limitation the first limitation of the current study is the relatively small number of respondents. although there are significant conclusions made based on the responses obtained from the survey respondents, the findings may not accurately reflect the opinion of the entire professionals in the omani construction sector. secondly, this study was conducted in the muscat governorate and all questionnaires were distributed amongst professionals who are working in muscat. the limitations identified by this study suggest that further studies should be conducted targeting the construction professionals who are working in cities other than muscat to increase the sample size and maximise the accuracy of the current results. results and discussion category factors related to factors rank mean score std. dev. rii project progress and development client design changes and variations during construction work. 1 3.54 1.14 0.708 consultant inadequate project management assistance 2 3.30 1.18 0.660 client lack of incentives for contractors to follow project schedule 3 3.22 1.20 0.644 contractor poor site management and supervision by a project manager. 4 3.16 1.14 0.632 contractor lack of materials 5 3.11 1.20 0.622 contractor shortage of labor and equipment 6 3.08 1.04 0.616 client consultant contractor poor communication and coordination with other project parties. 7 3.08 1.26 0.616 consultant poor supervision of consultant to contractor activities 8 3.05 1.10 0.610 contractor poor risk management and inappropriate handling of unexpected problems and crises 9 3.05 1.13 0.610 contractor inadequate implementation of health and safety procedures 10 2.95 1.18 0.590 contractor administrative corruption, indiscipline, and dishonesty 11 2.73 1.22 0.546 contractor frequent equipment breakdowns 12 2.62 1.01 0.524 overall 3.08 0.615 environment external emergence of natural factors, such as rainstorms, windstorms, and floods 1 2.78 1.18 0.556 general information of the respondents the respondent sample includes 17 client representatives, 27 contracting engineers and supervisors, 10 projects managers and 23 consulting architects/engineers. a total of 58% of the respondents work in various government construction projects, whereas 42% of them work in private construction projects. a total of 27, 23, 19, 5 and 3 of the respondents have total years of experience of 1–5, 6–10, 11–15, 16–20 and above 20 years, respectively. therefore, the respondents are adequately qualified to answer the distributed set of questions. critical factors affecting the success of construction projects in oman table 2 lists the riis for all factors used in this study. these factors, which affect the success of construction projects in oman, are classified into six main categories, namely, time; finance; project designing, planning and scheduling; quality; project progress and development; and environment and nature. the overall rii of the main categories is presented in table 3. journal of sustainable architecture and civil engineering 2021/2/29 130 table 3 shows that quality factors are the most important factors amongst the six investigated categories, whereas the environmental category is the least. the mean rii of quality factors category is 0.678, followed by time; finance; project progress and development; project designing, planning and scheduling; and environmental factors with the riis of 0.66, 0.628, 0.615, 0.601 table 3 overall mean riis of main categories category rii rank quality 0.678 1 time 0.660 2 finance 0.628 3 project progress and development 0.615 4 project designing, planning and scheduling 0.601 5 environment 0.556 6 and 0.556, respectively. this finding is consistent with the findings of ramlee et al. (2016) in which cost, time and quality were found the three main important csfs of construction projects, whereas safety, environment and resources were the least important ones. quality factors the results, presented in table 2, show that selecting a low bid, rather than an accurate and reliable bid, is a significant quality-related affecting factor of the success of construction projects in oman with an rii of 0.73. similarly, the quality of project team and experience of labour significantly affect the success of construction projects in oman, followed by the quality of subcontractors, suppliers and materials with riis of 0.73, 0.708, 0.692 and 0.638, correspondingly. although the quality and efficiency of the project manager are crucial, they rank the least quality-related factor that affects the success of construction projects in oman with an rii value of 0.572. values exceeding 0.5 are considered of large effects. these finding are consistent with the previous studies in which the selection criteria and tendering evaluation are considered important success factors of construction projects (fong & choi, 2000; chan et al., 2004; meland et al., 2011; oyegoke & al kiyumi, 2017). meland et al. (2011) argued that a high focus on price in the tendering evaluation of construction projects deteriorate the project outcome in terms of cost and quality. time factors table 2 shows that the delay in obtaining approvals from government authorities and the delay of clients and consultants in approving the drawings are two major time-related factors affecting the success of omani construction projects with riis of 0.702 and 0.682, respectively. these findings are consistent with the results obtained from previous studies in which the delays in obtaining the approvals of local authorities are considered a dominant affecting factor of the success of any development (ratcliffe & stubbs, 2003; evans, 2004; al adawi et al., 2020). although the delay in obtaining the approval of project management on critical issues, such as scope, resources and major tasks, is considered a significant factor that can derail a project from the beginning. the results show that the delay in obtaining internal approvals of the project manager is the least important time-related affecting factor of the overall success of the construction projects in oman with an rii of 0.610. finance factors the results of the present study, as summarised in table 2, confirm that the instability of the contractor’s financial background and the unavailability of a project financer are the two major financial-related factors affecting the success of construction projects in oman. the two factors have riis of 0.682 and 0.670, which imply high significance. these findings are consistent with the results obtained by abdul-rahman et al. (2011) who found that the client’s insufficient financial resources and the contractor’s unstable financial background are the most significant factors that lead to project delay. 131 journal of sustainable architecture and civil engineering 2021/2/29 although the client and contractor’s poor cash flow management is a significant reason for project failure, the results show that this factor with an rii of 0.59 is the least important financial-related affecting factor of the success of construction projects in oman. this factor ranks the least, but its rii exceeds 0.5 indicating that this factor is as important as the other factors. project progress and development factors the results of the present study, as summarised in table 2, show that the design changes and variations during the construction work exhibit a significant negative impact on the project performance and progress, thereby leading to project failure. this factor has an rii of 0.708. this finding is consistent with the findings of oyewobi et al. (2015) who found that variations during construction are time consuming and costly because they increase construction costs and time by 34% and 29.5%, respectively. the consultant shares advice, makes recommendations, solves problems and determines the optimal actions to be undertaken during the project duration to improve the project progress. poor project management assistance provided by the consultant to the project team leads to a disastrous result in the construction projects. this finding is confirmed by the survey results, where it ranks as the second significant factor that leads to construction project failure in oman with an rii of 0.66. however, the failure of equipment has subsequent impacts on the progress of the work and delivery of the services, this factor ranks the least project progress and development-related factors affecting the success of construction projects in oman with an rii of 0.524. project designing, planning and scheduling factors the study results, as presented in table 2, indicate that inadequate information provided by the client during feasibility studies ranks the major factor related to project designing, planning and scheduling with an rii of 0.638. the pre-construction information provided by the client to the contractors and designers during tendering, designing and planning stages must be clear, understandable, concise and in a convenient form to enable distinct performance of duties. consultants’ errors in design and failure to satisfy the design objectives rank the second factor with an rii of 0.616, whereas consultants’ misunderstanding of the client’s requirements and the project objectives is the least important with an rii of 0.568. environment and nature factors in the present study, the effect of bad weather conditions, such as rainstorms, winds, tornadoes and floods, is one of the least factors affecting the success of construction projects in oman. this factor has an rii of 0.556, which exceeds 0.5 and thus indicates that it is as important as the remaining factors. this finding contradicts with the results of previous research studies. chan et al. (2004( and akanni et al. (2015) stated that climatic condition and weather factors rank as the second most important amongst all external factors investigated in their studies. contribution of the project team in the success of construction projects in oman the results presented in tables 4–6 indicate that the factors related to the client have the highest impact on the success of construction projects in oman, followed by those related to the consultant and contractor with overall riis of 0.655, 0.635 and 0.624, respectively. client-related factors affecting the success of construction projects in oman the summary of results in table 4 indicates that quality, time and project progress are the most important categories related to the client’s role in the success of construction projects. the results of the current study are similar to the findings obtained in previous studies (fellows & liu, 1997; fong & choi, 2000; yong & mustaffa, 2012, al maktoumi et al., 2020). specifically, the respondents agree that the client’s selection of a low bid, rather than an accurate and reliable bid, is the key journal of sustainable architecture and civil engineering 2021/2/29 132 table 4 riis of clientrelated factors category factors rii time delay in approving the design drawings 0.682 client delay in payments 0.676 client delay in decision-making 0.670 delay in approving materials 0.664 delay in providing temporary utilities of water, electricity, and a/c for construction site 0.622 overall 0.663 finance lack of project financing 0.670 financial corruption 0.600 poor cash flow (irregular cash flow) 0.590 overall 0.620 project designing, planning and scheduling inadequate information provided by a client during feasibility studies 0.638 overall 0.638 quality selection of a low bid, rather than an accurate and reliable bid 0.730 overall 0.730 project progress and development design changes and variations during construction work 0.708 lack of incentives for contractors to follow project schedule 0.644 poor communication and coordination with other project parties 0.616 overall 0.656 client related factors-overall 0.655 client-related affecting factor of the construction projects in oman with an rii of 0.73, followed by the client’s design change and variation orders during a construction work with an rii of 0.708. delays during the design stage lead to an overall delay in the work and thus affect the success of the project. the findings of previous research studies carried out by muhwezi et al. (2014) and tayeh et al. (2018) are supported by the current results, which show that the client’s delay in design approvals is the third highest client-related factor with an rii of 0. 682. the availability of funding, regularity of payments, and the client’s poor financial management affect the project’s progress and success considerably (abdul-rahman et al., 2009; yong and mustaffa, 2012; homthong and moungnoi, 2016; tayeh et al., 2018). these findings are consistent with the current results, where a lack of project financing and the client’s delay in payments are highly important with riis of 0.67 and 0.676, respectively. consultant-related factors affecting the success of construction projects in oman similar to client-related factors, qualityand time-related factors are the most important categories related to the consultant’s role in construction project success. the respondents of the current survey agree that the quality and the experience of the consultant team and designers are crucial success factors with an rii of 0.73, as summarised in table 5. this finding matches with the findings of previous studies conducted by homthong and moungnoi (2016) and tayeh et al. (2018), where the quality, experience of the design team and experience of project participants considerably affect the quality and outcomes of the project because successful projects require an experienced team to execute the work. the current results indicate that the consultant’s delays in approving the design drawings and materials significantly affect the overall delay of the construction project and thus the project success. 133 journal of sustainable architecture and civil engineering 2021/2/29 the riis of these factors are 0.682 and 0.664, respectively. the design activity is broadly conducted by consultants to translate the client’s goals and concepts into workable construction systems. muhwezi et al. (2014) analysed the consultant’s misunderstanding of the client’s requirement; this factor is significant with an rii of 0.742. in the present study, the consultant’s misunderstanding of the client’s requirement and project objectives has been found as the least important consultant-related affecting factor of the success of construction projects in oman. the rii of this factor is 0.568, which exceeds 0.5 and thus indicates that it is as important as the remaining factors. table 5 riis of consultantrelated factors category factors rii time delay in approving the design drawings 0.682 delay in approving materials 0.664 overall 0.673 finance financial corruption 0.600 overall 0.600 project designing, planning and scheduling errors in design and failure to satisfy design objectives 0.616 insufficient data collection and survey prior to design 0.600 misunderstanding of owner requirement and project objectives 0.568 overall 0.595 quality unqualified/ inadequate experienced team 0.730 overall 0.730 project progress and development inadequate project management assistance 0.660 poor communication and coordination with other project parties 0.616 poor supervision of consultant to contractor activities 0.610 overall 0.629 consultant related factors-overall 0.635 contractor-related factors affecting the success of construction projects in oman similar to consultant-related factors, table 6 shows that quality, time and finance factors are the most important categories related to the contractor’s role in construction project success. the respondents of the current survey agree that the quality and experience of the contractor team and labour are the most important factors related to the contractor’s role in ensuring the success of the construction project. this result is consistent with the findings obtained in previous studies (yong & mustaffa, 2012; muhwezi et al., 2014; homthong & moungnoi, 2016; tayeh et al., 2018). unqualified/inadequately experienced labour, unqualified subcontractors and unqualified suppliers are identified as the key factors related to contractors with riis of 0.73, 0.708 and 0.692, respectively, tayeh et al., 2018 stated that the contractor’s financial situation and inability to perform the work affect the project progress negatively and thus lead to project failure. this finding is nearly similar to the current results, where the contractor’s unstable financial situation with an rii of 0.682 is the fourth highest contractor-related factor. contrary to the findings of muhwezi et al. (2014), the current results show that several contractor-related factors slightly influence the success of construction projects in oman; these factors include incompetent project manager with an rii of 0.572, administrative corruption, indiscipline and dishonesty with an rii of 0.546 and frequent equipment breakdowns with an rii of 0.524. journal of sustainable architecture and civil engineering 2021/2/29 134 external factors the current study states that the delay of government authorities in issuing approvals with an rii of 0.702 is the key external affecting factor of the success of construction projects in oman. the financial stability report of oman indicated that the inflation rate increased from 0.1% in 2015 to 2.8% in march 2017, and the rate is expected to increase to an average of 4.1% in 2017 and stabilise at approximately 3% in 2020 (central bank of oman, 2017). this increase in the inflation rate significantly affects the construction sector in oman, as confirmed by the current study. table 7 shows that the respondents of the survey agree that inflation rate, increase in material prices and labour and transportation costs greatly affect the success of construction projects in oman with an rii of 0.638 which is matching the finding of abdul-rahman et al. (2009). the severe weather condition, which is a physical factor with an rii of 0.556, is the least external affecting factor of the success of construction projects in oman. this finding is consistent with that of yong & mustaffa table 6 riis of contractorrelated factors category factors rii time shortage and delay in material supply 0.664 unrealistic project timelines 0.648 project manager delay in making and issuing decisions 0.610 overall 0.641 finance contractor’s unstable financial situation 0.682 financial corruption 0.600 poor cash flow (irregular cash flow) 0.590 overall 0.624 project designing, planning and scheduling ineffective project planning and schedule 0.584 overall 0.584 quality unqualified/ inadequate experienced labor and team 0.730 unqualified sub-contractors 0.708 unqualified suppliers 0.692 poor quality of materials 0.638 incompetent project manager 0.572 overall 0.668 project progress and development poor site management and supervision by a project manager 0.632 lack of material 0.622 shortage of labor and equipment 0.616 poor communication and coordination with other project parties 0.616 poor risk management and inappropriate handling of unexpected problems and crises 0.610 inadequate implementation of health and safety procedures 0.590 administrative corruption, indiscipline, and dishonesty 0.546 frequent equipment breakdowns 0.524 overall 0.595 contractor related factors-overall 0.624 135 journal of sustainable architecture and civil engineering 2021/2/29 based on the above-mentioned discussions and the opinions of the respondents, the following conclusions can be drawn based 1. factors related to quality rank the most important amongst the investigated factors that affect the success of construction projects in oman 2. factors related to clients are the most important, followed, in sequence, by those related to consultant, contractor and external environment. 3. the most important factor affecting the success of projects in oman are the selection of the lowest bid, and the quality and experience of the project team. 4. the least important factors affecting the success of construction projects in oman are the contractors’ administrative corruption, indiscipline and dishonesty and the frequent equipment breakdowns. to improve the construction industry in oman, the following actions are recommended by the authors: 1. a non-profit independent organisation should be established to conduct workshops for sharing best practices and strengthening public awareness on the impact of construction on the national economy. 2. the government should force the construction companies to improve both procurement strategies and approaches to project delivery. 3. the government should facilitate the foreign direct investment by simplifying procedures and providing a smooth investment environment. recommendation for future studies 1. further studies that target the construction professionals working in cities other than muscat should be conducted to increase the sample size and maximise the accuracy of the current results. 2. future studies on the government’s responsibilities in ensuring the success of construction projects should be performed. conflict of interest the authors declare that they have no conflict of interest. acknowledgements declared none. table 7 riis of external factors category factors rii time delay in issuing approvals by authorities 0.702 overall 0.702 finance inflation (material prices, labor, and transportation costs) 0.638 poor economic conditions 0.590 overall 0.614 environmental emergence of natural factors, such as rainstorms, windstorms, and floods 0.556 overall 0.556 external related factorsoverall 0.622 conclusions and recommendations (2012), who reported that the weather condition factor is the least significant amongst 15 critical factors affecting the success of construction projects in malaysia. journal of sustainable architecture and civil engineering 2021/2/29 136 abdul-rahman, h., takim, r., & min, w. j. 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(2012). analysis of factors critical to construction project success in malaysia, engineering, construction and architectural management, 19 (5), 543-556. https://doi. org/10.1108/09699981211259612 rami hamad assistant professor international college of engineering and management main research area construction management structural engineering concrete technology address p.o. box 2511, c.p.o seeb, p.c. 111, oman tel.: 0096871938475 e-mail: rami@icem.edu.om bassam a. tayeh associate professor islamic university of gaza main research area construction management structural engineering concrete technology address p.o. box 108, gaza strip, palestine, e-mail: btayeh@iugaza.edu.ps hamdan a. al aisri hse advisor arabian industry projects main research area construction management address p.o. box 2511, c.p.o seeb, p.c. 111, oman e-mail: hamdanalesry@gmail.com about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 153 journal of sustainable architecture and civil engineering 2022/1/30 structural assessment of the sustainability of the historical clock tower as a landmark *corresponding author: merve.ozkaynak@hotmail.com structural assessment of the sustainability of the historical clock tower as a landmark received 2021/04/13 accepted after revision 2022/01/10 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 153-162 doi 10.5755/j01.sace.30.1.28882 jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.28882 merve özkaynak, burçin şenol şeker amasya university, faculty of architecture, amasya, turkey abstract in the historical process, many tools have been used to measure time. with technological advances, clock towers were built with mechanical clocks. but today, rather than their original function, historic urban centers have become an image of cities. first built in europe, clock towers were built in various cities of anatolia during the ottoman period. the protection and sustainability of clock towers, which are one of physical identity, is important for the continuity of cultural heritage. determining the damages that earthquakes will contribute to the protection and sustainability of clock towers. in the study, the historical clock tower in çorum was modeled in three dimensions and subjected to static and dynamic analysis. in static analysis, it is seen that the upper part of the main entrance door and dynamic analyses increase in the transition from the octagonal plan in the lower region to the circular cross-sectional zone in the upper region. also, it was determined that the maximum values of deformations appeared as displacement in orthogonal directions at the top of the tower. as a result, as a strengthening proposal, it is thought that iron tensioners passing through the stirrup plane of the entrance door conveyor belt should be added. keywords: clock tower, dynamic analysis, finite element analysis, static analysis, urban identity. introduction kevin lynch (1960) in the cities of boston, jersey city and los angeles in his book “the image of the city”, urban identity components of physical identity components into five groups as include paths, node, district, and landmark. landmarks, which are the unique images of the city, which are called the symbols and totems of the cities, provide the definition of the city, and create the sense of belonging to the citizens. buildings that are the reference point of the city, symbolize a city or region, provide distinctiveness from other settlements, and add identity to the place are defined as landmarks. lynch (1960) referred to these signs as a physical object such as a building, sign, store, or mountain. landmarks such as the eiffel tower, statue of liberty, burj khalifa, burj al arab hotel, sydney opera house or the egyptian pyramids have become the symbols of the cities they belong to and have played an important role in the recognition of the cities. mechanical clocks, invented to measure the concept of time that is important to humanity, were in the towers or building facades built. the clock towers, which are a sign of power and wealth, started to be built in the ottoman empire after europe and spread rapidly in anatolia. today, clock journal of sustainable architecture and civil engineering 2022/1/30 154 towers with different architectural styles and typological characteristics form an important part of cultural and architectural heritage. the clock towers, which were built as an independent structure or as part of the historical structure, are important landmarks that form the silhouettes of the historical city centers today. clock towers, one of the images of cities, must be preserved for cultural sustainability. in this context, this study aims to investigate the structural behavior of historical clock towers in turkey, which is located on important earthquake fault lines, and to present proposals for restoration works to be carried out. the architectural features of the clock towers, which are one of the symbols of historical cities, have been researched in the architectural literature for their preservation and sustainability. the effects of clock towers in different cities on the urban identity, visual effects on the silhouettes of cities, and creating a square were investigated from an architectural and design perspective (gelmez & altıntaş, 2018; gulick, 2007; hung, 2003). in addition to architectural research, in engineering and earthquake engineering, studies on clock towers have been researched the behavior of structures under static and dynamic effects, and restoration suggestions were made. the fact that the building material of the historical clock towers is stone increases the risk of demolition and damage due to the delicateness and structural irregularity of the structure (ferraioli, miccoli, & abruzzese, 2017). there are various studies on this subject in the literature; improvement and strengthening recommendations are presented with linear and nonlinear analyses. in this context; zarandi and maheri (2008) examined the dynamic properties of brick masonry towers by including ground parameters. towers with different heights, material properties, and geometry were subjected to detailed analysis in the finite element environment according to the location of the earthquake epicenter and the intensity of the earthquake for different ground types. as a result, the effect of the relevant parameters on the dynamic behavior of the towers has been determined. mirtaheri, abbasi, and salari (2017) presented data on a historic minaret in iran in the first stage, including geometry and material properties. he then measured the structure with the devices and determined the dynamic characteristics of the minaret. by modeling the minaret in three dimensions in the numerical environment, the results obtained were compared with the results of the experiments, and recommendations were presented. şeker (2015) examined the structural behavior of two separate historical clock towers built on existing historical buildings in amasya province. in the study, static and dynamic analyses of towers modeled in three dimensions in a numerical environment were performed. during the earthquake, it was determined that the additions reduced the strength of the existing historical structure. girardi, padovani, and pellegrini (2017) tested a newly developed application for modal analysis of masonry structures in a clock tower in lucca. in this method, the effects of the stress area consisting of thermal changes are taken into account in the calculation of structure natural frequencies and mode shapes. akbaş and çakır (2014) analyzed based on the performance of a historic clock tower in eastern turkey. korumaz et al. (2017), attia, sayed, and abdel-haleem (2010), mustafaraj and yardım (2016), and pavlovic, trevisani, and cecchi (2016) created a three-dimensional model of a historical tower (minaret or clock tower) in a finite element environment and its static and dynamic analyzes were made. it has determined the difficult parts of the building and the parts that need improvement. soyluk and i̇lerisoy (2013) analyzed the model of the dolmabahçe historical clock tower in istanbul in a finite element environment with ground effects. milania, shehua, and valentea (2017) analyzed the historical clock tower using non-linear static procedures. sarhosis, fabbrocino, formisano, and milani (2017) proposed a formula for estimating the precision of towers, taking into account the parameters of the fragility and cross-sectional area of masonry towers with different geometries. acito, bocciarelli, chesi, and milani (2014) analyzed non-linear static (pushover and kinematic limit analysis) under two main seismic events of a clock tower. 155 journal of sustainable architecture and civil engineering 2022/1/30 history of clock towers as landmarks although the clock was first developed in the east in the historical process, clock towers were first built in the west. in 1386, the oldest tower clock was placed in salisbury cathedral in england. in 1389, a clock tower that rings every quarter-hour was built in rouen, france (rossum, 2003). clock tower construction, which became widespread in europe in the 14th century, started in the ottoman empire at the end of the 16th century and spread from west to east in the 18th and 19th centuries (acun, 2008). the first clock tower in the ottoman period was built in bosnia-herzegovina in 1579 by bosna governor ferhat pasha (acun, 1993). the first clock tower in anatolia was built in safranbolu in 1797 (figure 2a) (acun, 1994). clock towers were built throughout the ottoman empire during the reign of ii. abdülhamit in 1901, when he directed the governors to build clock towers with the cülus, which gold coin distributed by the sultan (acun, 2008). tower and facade clocks in every town in europe were first built in the ottoman period to adopt western culture. however, since the european clock was not used in the ottoman empire yet, it was built to show the power of the state, as it has symbolic meanings. (kokal, 2007). mechanical clocks have been attracted by the public since their first arrival in istanbul and have spread rapidly in mosques, timing houses, building facades, and residences (üçsu, 2011). clock towers, usually built by courtiers or governors, were built in historical city centers and on the peaks of settlements. clock towers are in areas such as mosques, churches, palaces, mansions, and municipalities overlooking the public squares. squares designed around clock towers in europe began to emerge in the ottoman empire (figure 2b). clock towers, which are an indispensable part of life in the historical process, have become an important part of the urban fabric. today, it has become one of the components of the identities of historical cities. çorum clock tower architectural properties çorum clock tower is in the city square in the historical city center of çorum province (figure 3). around the clock tower, there is a mosque, church, turkish bath, ottoman bazaar, khan, and government house. according to the inscription of the building on the round-arched door of the clock tower opening to the south, it was built by beşiktaş guard çorumlu hasan pasha in 1896 during the abdulhamid period. (acun, 2011). built with yellow-cut stone material, the body section of the tower sits on an octagonal pedestal. the octagonal pedestal of the clock tower at an altitude of 28 meters is 3.90 meters long (acun, 1994). the shoe on the octagonal pedestal passes to the trunk. there is a tower balcony at the top of the body. literature review of contextual and conceptual foundations fig. 1 examples of clock towers a)castello estense in ferrara b)piazza cattedrale in ferrara (gürcu, 2016) (a) (b) fig. 2 clock tower in anatolia a) safranbolu clock tower (özkaynak, 2018) b)tokat clock tower (özkaynak, 2020) (a) (b) journal of sustainable architecture and civil engineering 2022/1/30 156 an 81-step staircase leads to the tower balcony section through the round-arched door (acun, 1994). the honorary part of the building is surrounded by iron railings. above the tower balcony is a square-form mansion. there is one hour on the four fronts of the pavilion section and there are diamond-shaped windows on the dials. the top of the structure is covered with a lead-covered dome. the section between the pedestal part of the structure and the balcony was built in the form of a minaret, while the top section of the balcony was built in the form of european clock towers. fig. 3 çorum clock tower (url-1) methods in this study, it was aimed to restore a historical clock tower, which is a landmark of a city, in accordance with the earthquake, and to protect it during the earthquake and its sustainability. in this context, the behaviour of the historical çorum clock tower, which was chosen as a sample, was examined by using the records of a large earthquake that took place before. in this study, which is a case study for clock towers, the historical tower was first modelled in 3d. in the second stage, the static analysis of the structure was made according to the physical and mechanical material properties of the model using the ansys program. in the third stage, mode shapes were obtained by modal analysis of the historical tower. finally, maximum stress values and total deformation values in east-west and north-south directions were obtained by time history analysis under the erzincan earthquake records in 1992. as a result of the findings, structural assessment of the historical clock tower was determined during earthquake, and a restoration proposal was made for the sustainability of the city’s landmark. material properties to analyze the structural assessment of historical buildings during the earthquake, it is necessary to determine the material properties. because of the cultural value of historical buildings, destructive experiments and samples cannot be taken on the building. regarding the heterogeneous structure of the tower, the real mechanic and physical properties can be calculated approximately. in the clock tower investigated in this study, it is seen that sandstone, which has the same characteristics as other historical buildings in the region, was used. the results of the test on stone samples taken from a historical mosque in the district of merzifon near the building are given in table 1 (şeker, çakır, doğangün, & uysal, 2014). the properties given below are also used for the analysis of the clock tower. structural analysis it is necessary to make some acceptances for the analysis of masonry structures with complex geometry and heterogeneous material properties such as historical towers. firstly, when material properties are taken into account, tydryk (2017) the mechanical and physical properties of table 1 physical and mechanical properties of the materials used in the clock tower structure material modulus of elasticity (young modulus)(pa) poisson’s ratio specific bulk density (kg/m³) mean compressive strength (mpa) mean tensile strength (mpa) masonry 1,018e+10 0,17 2358 50,92 5,092 157 journal of sustainable architecture and civil engineering 2022/1/30 the masonry wall are defined according to a different unit and mortar strengths. in this way, the mechanical and physical properties of the wall can be determined depending on the strength of the units that make up the masonry structure. these obtained features are assigned as material properties to the model created in the finite element environment and static and dynamic analyses are conducted. in terms of modeling, this material, which is assigned as a single gross part in the tower finite element environment, is connected to the floor by built-in bearing and it is accepted that the parts that make up the structure are fully connected and there are no deformations such as deterioration or disintegration. the structure is analyzed according to these acceptances. the three-dimensional model of the tower is seen in figure 4. the structure is analyzed by accepting linear elastic material under its load. although the material can work beyond linear, this analysis is useful for determining the forced regions of the structure in the first place and for detailed determination of the load flow. in such highly delicate structures, this analysis fig. 4 çorum clock tower finite element model results can yield valuable results. ansys finite element program was used in the analysis for this purpose. in the analysis, the finite element solid 186, available in the ansys library, with displacement on all three axes, was considered. fig. 5 çorum clock tower static analysis total deformation distribution static analysis the clock tower finite element model has been analysis by ansys. the model consists of 40517 nodes and 12624 elements in total. the results of the analysis are shown in figure 5. the study also covered the drucker-prager material model (betti & vignoli, 2008). when the results of the analysis are evaluated, it is seen that the deformations have maximum values at the top of the tower and the values towards the lower regions decrease. the maximum deformation value is 0.78 mm mpa. when the movement of the deformation shape in the finite element environment is examined, it is determined that the deformations are concentrated in the sections where the tower section expands in the lower regions and the upper areas of the entrance door below it. side openings can be expected in these regions because of vertical weight (figure 6). when the static analysis stress distribution is examined, it is seen that the stresses reach maximum values in the upper region of the main entrance gate in the lower region. with the increase of vertical loads in this region, stresses occur where the arched part of the main door that creates the gap is located, and over time it becomes a stretch of pulling and becomes able to break the stability of this region by opening the keystone. an improvement should include increasing the thickness of this area or a tensioner system that will connect the arch points (figure 7). fig. 6 çorum clock tower deformation distribution on x-axis by static analysis5 6 journal of sustainable architecture and civil engineering 2022/1/30 158 fig. 7 çorum clock tower static analysis maximum principal stress distribution modal analysis with modal analysis, which constitutes an important part of dynamic analysis, free vibration mode shapes of the structure are determined. this analysis informs about the way the structure moves during the earthquake, and accordingly, the forced areas of the structure can be determined. a total of 200 mode shapes were discussed table 2 modal analysis periods and mass participation ratios mode period mass participation ratios x axis y axis 1 0.39151 0.000100468 0.393824 2 0.38391 0.39180 0.00010 3 0.084036 0.226211 0.00010 4 0.082474 0.000216 0.21047 according to the article specified in the earthquake regulation, which stipulates that the active mass in both directions should be handled not less than 90% of the total building mass. the mod contribution rates and periods of the most effective of these mode shapes were calculated and given in table 2 (figures 8 and 9). when the active mode shapes are examined, it is observed that the main movement is a displacement in two directions, and in the form of another effective mode in the advancing modes, the off-plane behavior of the parts close to the upper regions of the tower is effective with the displacement. with these displacement patterns, it is determined that the structure will be intensified in the lower regions of the tower, in the transition from the octagonal planned part to the circular area above, and the lower areas of the tower balcony part. time history analysis the geography of turkey is in a large earthquake zone. many different fault lines are active in turkey. the north anatolian fault line is one of them. there have been some very damaging earthquakes on this line in the past. the clock tower researched in this study is also located on this fault line. therefore, it is important to examine the structural assessment during the earthquake. for this purpose, the structure was analyzed in the field of time definition in both orthogonal directions and the results obtained were given. in this analysis method, the structure was examined under the 1992 erzincan earthquake record, which was effective in the region. the records of earthquake acceleration, east-west, and north-south direction were applied to the structure in the same direction of the structure. the time step was taken as 0.005 and the 10 sec time frames 159 journal of sustainable architecture and civil engineering 2022/1/30 fig. 8 çorum clock tower modal analysis 1st and 2nd mode shapes fig. 9 çorum clock tower modal analysis 3rd and 4th mode shapes containing the maximum values of acceleration was discussed in the analysis. as a result of the analysis, stresses and deformations of the structure were calculated. earthquake acceleration values are seen in figure 10. when figure 11 is examined, it is seen that the maximum stresses occur in the tower transition zone. as a result of horizontal displacement, which is effective in dynamic analysis, it is determined that these regions will be subjected to large tensile stresses by shifting similarly to the movement of the built-in beam. it is seen that the maximum stress generated in the 10-sec depress recording is 12.15 mpa and this value occurs at 2.965 s. when the deformation change in figure 12 is examined, it is observed that the maximum deformation occurs at the top point of the tower as displacement. the horizontal displacement value is 52.21 mm. the ratio of horizontal disfig. 10 erzincan earthquake acceleration record values(mm/sn2) journal of sustainable architecture and civil engineering 2022/1/30 160 placement to tower height is 52.21/27500=0.001898 and remains below the 0.003 limits given in the regulation. when the analysis results in figure 13 are examined, it is seen that the prime stress values formed in this direction (north-south) analysis reached 8.85 mpa, which is also in the same region but lower. it can be considered that the entrance door cavity causes this stress differentiation. again, it was determined that the total deformation value reached 48.593 mm, which was aha? low. the ratio of horizontal displacement to tower height is 48,593/27500=0.00177, which is considerably lower than the 0.003 limits given in the tydryk (2017). fig. 13 erzincan earthquake north-south direction analysis t= 3.035 sn principal stress values distribution fig. 11 erzincan earthquake east-west direction analysis t= 2.965 sn principal stress values distribution fig. 12 erzincan earthquake east-west direction analysis t= 2.96 sn total deformation values distribution 161 journal of sustainable architecture and civil engineering 2022/1/30 fig. 14 erzincan earthquake north-south direction analysis t=3.04 seconds total deformation values distribution historical buildings are the most important structures that reflect the historical, cultural, social, and economic structures of the cities, the traditions, and customs of the past civilizations, the construction techniques, and the materials they use. the components of urban identity must be preserved and onto future generations with their sustainability. in this context, historical buildings need to be strengthened with appropriate techniques and methods to increase their resilience to external influences. with today’s technology, appropriate interventions can be made timely and accurately by detecting areas of such artifacts that can be easily examined in a finite element environment, especially in the face of the most important destructive impact, such as earthquakes. in this study, the historical clock tower of çorum, an image of the city, was subjected to static and dynamic analysis. as a result, it was determined that the upper area of the tower entrance door and the tower crossing area are sensitive areas to deformation and strain. çorum clock tower, one of the components of urban identity, can be protected by strengthening operations from the designated points. also, with the method applied in this study, the earthquake behavior of clock towers should be examined, protected, and onto future generations. it is expected that the findings from this study will be a guide for the experts working in this field. conclusions referencesacito, m., bocciarelli, m., chesi, c., milani, g. collapse of the clock tower in finale emilia after the may 2012 emilia romagna earthquake sequence: numerical insight. engineering structures, 2014; 72, 70-91. https:// doi.org/10.1016/j.engstruct.2014.04.026 acun, h. saray-bosna ve travnik saat kuleleri x. vakıf haftası kitabı (pp. 295-298): c. başbakanlık genel müdürlüğü yayınları; 1993. acun, h. anadolu saat kuleleri; 1994. acun, h. saat kulesi. i̇stanbul: türkiye diyanet vakfı; 2008 (35). acun, h. osmanlı i̇mparatorluğu saat kuleleri. ankara: atatürk kültür merkezi yayınları; 2011. akbaş, b., çakır, f. performance-based evaluation of historical structures. paper presented at the workshop on seismicity of historical structures, i̇stanbul. 2014. attia, w. a., sayed, t. a. e., abdel-haleem, a. a. behavior, repair & strengthening of historic stone masonry towers. paper presented at the second international conference on construction in developing countries, cairo, egypt, 2010. betti, m., vignoli, a. modelling and analysis of a romanesque church under earthquake loading: assessment of seismic resistance. engineering structures, 2008; 30, 352-367. https://doi.org/10.1016/j.engstruct.2007.03.027 ferraioli, m., miccoli, l., abruzzese, d. seismic risk assessment of the santa maria a vico bell tower. ambient vibration measurements and numerical model tuning. paper presented at the 3rd international conference on protection of historical constructions lisbon, portugal. 2017. gelmez, e., altıntaş, m. clock towers as the focus of city square: the changing scale of nusretiye clock tower. the turkish online journal of design, 2018; 8(1), 79-96. https://doi.org/10.7456/10801100/008 girardi, m., padovani, c., pellegrini, d. effects of the stress field on the dynamic properties of masonry bell journal of sustainable architecture and civil engineering 2022/1/30 162 towers. paper presented at the xxiii congresso associazione italiana di meccanica teorica e applicata aimeta, salerno, italy. 2017. gulick, j. images of an arab city. journal of the american institute of planners, 2007; 29(3), 179-198. https:// doi.org/10.1080/01944366308978063 gürcu, l. t. (2016). 19. yüzyıl osmanlı dönemi saat kuleleri bağlamında istanbul nusretiye saat kulesi ve koruma projesi. mimar sinan fine arts university. hung, w. monumentaltiy of time: giant clok, the drum tower, the clock tower. in r. s. nelson & m. olin (eds.), monuments and memory, made and unmade (vol. 5, pp. 107-132): the university of chicago press; 2003. kokal, ö. saat kuleleri. yapı dergisi, 2007. korumaz, m., betti, m., conti, a., tucci, g., bartoli, g., bonora, v., korumaz, a. g., fiorini, l. an integrated terrestrial laser scanner (tls), deviation analysis (da) and finite element (fe) approach for health assessment of historical structures.a minaret case study. engineering structures, 2017; 153, 224-238. https://doi. org/10.1016/j.engstruct.2017.10.026 lynch, k. (1960) the image of the city. cambridge: technology press. milania, g., shehua, r., valentea, m. seismic assessment of masonry towers by means of nonlinear static procedures. paper presented at the xth international conference on structural dynamics, rome. 2017. https://doi.org/10.1016/j.proeng.2017.09.022 mirtaheri, m., abbasi, a., salari, n. a seismic behavior and rehabilitation of the historic masonry minaret by experimental and numerical methods. asian journal of civil engineering, 2017; 18(5), 807-822. mustafaraj, e., yardım, y. determination of structural behavior of a unreinforced masonry clock tower using fem analysis. american journal of engineering research, 2016; 5(1), 100-104. özkaynak, m. (2018). personal archive. özkaynak, m. (2020). personal archive. pavlovic, m., trevisani, s., cecchi, a. experimental and numerical analysis of a historical bell tower. world academy of science, engineering and technology international journal of civil, environmental, structural, construction and architectural engineering, 2016; 10(12), 1413-1420. rossum, g. d. v. yaşanan zaman ölçülen zaman. sanat kültür antika dergisi, 2003; (20), 18. sarhosis, v., fabbrocino, f., formisano, a., milani, g. seismic vulnerability of different in geometry historic masonry towers. paper presented at the 6th eccomas thematic conference on computational methods in structural dynamics and earthquake engineering, greece. 2017. https://doi. org/10.7712/120117.5585.17918 soyluk, a., i̇lerisoy, z. y. dynamic analysis of dolmabahce masonary clock tower. građevinar, 2013; 65(4), 345-352. https://doi.org/10.14256/jce.885.2012 şeker, b. ş. behavioural assessment of clock towers subsequently added to historic structures. građevinar, 2015; 67(9), 879-886. şeker, b. ş., çakır, f., doğangün, a., uysal, h. investigation of the structural performance of a masonry domed mosque by experimental tests and numerical analysis, earthquakes and structures, 2014; 6(4), 335-350. https://doi.org/10.12989/eas.2014.6.4.335 tydryk. (2017). tarihi yapılar için deprem risklerinin yönetimi kılavuzu. ankara, turkey: general directorate of foundation. url-1. retrieved 10.04.2021, 2021, from www.kulturportali.gov.tr üçsu, k. (2011). osmanlı i̇stanbul’unda zamanı belirlemek için kullanılan araçlar, mekanlar ve ilgili uzmanlar. i̇stanbul university. zarandi, s., maheri, m. r. seısmıc vulnerability of historical brick masonry towers. paper presented at the the 14 th world conference on earthquake engineering, beijing, china. 2008. about the author merve özkaynak position at the organization amasya university, faculty of architecture, department of architecture main research area urban identity, historical environment, building design. address amasya university, faculty of architecture, department of architecture, yeşilırmak campus, floor 3, room no:311. tel. +903582500017 e-mail: merve.ozkaynak@hotmail.com this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). journal of sustainable architecture and civil engineering 2023/1/32 196 mineral additives based on industrial waste for modifications of bitumen polymers received 2022/10/13 accepted after revision 2023/04/17 mineral additives based on industrial waste for modifications of bitumen polymers jsace 1/32 g. aitkaliyeva*, a. amitova satbayev university, institute of geology, oil and mining, satbayev st. 22, almaty, kazakhstan m. yelubay toraighyrov university, department of chemistry and chemical technology, lomov st. 64, pavlodar, kazakhstan d. vaičiukynienė kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania a. ismailova, g. ibraimbayeva international educational corporation (kazgasa), faculty of building technologies, infrastructure and management, ryskulbekova 18, almaty, kazakhstan *corresponding author: g.aitkaliyeva@satbayev.university https://doi.org/10.5755/j01.sace.32.1.32505 journal of sustainable architecture and civil engineering vol. 1 / no. 32 / 2023 pp. 196-204 doi 10.5755/j01.sace.32.1.32505 abstract the increase in cost of carbonaceous materials, as well as significant costs of industrial waste, have prompted scientists to use alternative raw materials as components of the construction industry. this study investigated the suitability of waste products from the coke industry as modifying agents for polymer bitumen. the by-product of the coking industry reaches a high level of silicon and is called siliconcontaining additive (sca), the composition of which is similar to the mineral solutions for bitumen. in this article, the results of using sca as standard additives for modified polyethylene terephthalate (pet) with bitumen waste is presented. using the simdist boiling point distribution method, simulated high temperature distillation by gas chromatography, differential thermal (dta) analyzes, and other methods of physicchemical properties of bitumen after adding of sca were studied. it was revealed that the connection and consumption of additives occurs because of the content of aromatic components, as well as an increase in the consumption of bitumen characteristics. thus, the presented method for obtaining road surfaces based on pet waste and coke production waste meet the requirements of sustainable development, which implements both a significant use of industrial waste as secondary products and their processing into a new product using an energy-saving technology that reduces the consumption of raw materials and resources. keywords: bitumen, chemical industry waste, mineral additives, modifiers, road materials, silicon-containing additive. 197 journal of sustainable architecture and civil engineering 2023/1/32 introduction it is known (zhang et al. 2022) that bitumen is one of the most important components of asphalt concrete, characterizing the strength and service life of road surfaces. as a result of numerous studies of various characteristics of bitumen, it has been found that bitumen modification can minimize the problems associated with damage to road materials, an increase in the frequency of their laying, as well as maintenance and repair costs (yaro et al., 2021). various polymeric materials are used as modifiers for bituminous binders, such as thermoplastic polymers (polyethylene, polypropylene, polyvinyl chloride, etc.), thermoplastic elastomers (styrene butadiene styrene (sbs), styrene isoprene styrene (sis), etc.). however, the use of polymers according to azahroosh et al. (2020) is limited due to the following disadvantages: their disproportionate effect on asphalt viscosity, incompatibility with the bituminous matrix and, most importantly, high cost. in this regard, the use of waste that has no residual value and causes a serious environmental problem plays a leading role as a green investment movement (santagata et al., 2007; abdul-rauf et al., 2010). waste rubber (nongnard et al., 2004) and used car tires in the form of crumbs and rubber powder are of great interest for the modification of bituminous binders. research by adhikari et al., (2000); de almeida junior et al. (2012); jamal et al. (2020) showed that waste rubber tires could be incorporated into an asphalt mix to improve asphalt pavement performance. therefore, mashaan et al. (2013) describes the improvement in the stability and adhesion of asphalt mixtures after the introduction of crumb rubber. however, the authors (porto et al., 2019) concluded that a large number of factors could influence the characteristics and mechanical properties of the rubber/ bitumen system, such as rubber size and content, chemical structure, particle surface properties (granulation in ambient conditions, environment / cryogenic grinding of tire rubber), method and conditions for obtaining a mixture). scientists believe that the rubber content of about 4% does not have a significant effect on the operational and mechanical properties of bitumen, and increasing the content to 20% is unsuitable. another waste used to modify asphalt mixes for non-rigid pavement construction is crushed concrete. the use of these wastes has a number of benefits, including increased pavement productivity, since it involves the production of new road materials by crushing old roads and using these materials as the base layer for a new asphalt pavement (jung et al., 2020; atisan et al., 2009; milad et al., 2018). however, the use of recycled concrete crushed stone as a modifier requires the removal, destruction and transformation of concrete into a material of a certain quality and size. the paper (remišová et al., 2017) concluded that additives in the form of various fabrics, fibers, zeolites, etc. do not affect the structure of bitumen, therefore, modification does not occur, and however, a change in the properties of bitumen is observed. there is considerable interest in plastic waste, such as polyethylene terephthalate (pet) waste, as modifiers. our works (aitkaliyeva et al., 2022) have previously shown the possibility of their use for modifying bitumen binders. high compatibility of pet with bitumen due to the formation of new oxygen-containing functional groups in the composition of new materials, as well as an increase in the content of asphaltene components in the composition of coatings, which indicates hardening with bituminous binders and an improvement in their viscosity-temperature stability. possible directions for further improvement of the properties of bitumen and polymer-modified bitumen are functionalization and development of new additional additives by zhu j. et al. (2014). in this direction, developments in the field of new additives for compatibility and improvement of adhesion are useful. mineral clays composed of tetrahedral layers of silicate and octahedral sheets of hydroxide martínez-anzures et al. (2018) were studied as modifiers in the polymer of bituminous binders by zapién-castillo et al. (2016). these include montmorillonite, rectorite and kaolinite, which are journal of sustainable architecture and civil engineering 2023/1/32 198 important due to their effective use in asphalt modification technology (hernandez et al., 2006; yu et al., 2007). to reduce the cost of the resulting modified bitumen, some waste and by-products of production can be of great success, which can be used as an alternative to kaolinite and montmorillonite. therefore, studies aimed at studying the possibility of the potential use of industrial waste as mineral additives for the modification of polymeric bitumen are relevant. to fill a gap in research, as well as to improve the efficiency of using the bitumen/pet flex system described in our previous work (aitkaliyeva et al., 2022), here we report the use of coke production waste as a mineral additive for modifying a polymer–bitumen binder. methods property requirement value needle penetration depth, 0,1 mm at 25 °с 70-100 73 ductility, mm 70 70 softening point, °с 43-52 52 table 1 the main properties of bitumen fig. 1 laboratory material sca at room temperature materials asphalt binder was road oil bitumen with 70/100 penetrationgrade. the properties of the binder are presented in table 1. polyethylene terephthalate (pet) waste, the main characteristic of which is presented in aitkaliyeva g. et al. (2022) served as a polymer for bitumen modification. a silicon-containing additive (sca) as a modifying agent for the polymer of bituminous binders was studied. sca a production waste from the calcination of crude petroleum coke at the “upnk-pv llp” plant of kazakhstan. the sample, designated as sca, can be seen in fig. 1, the physical properties are presented in table 2. study of the composition of the siliconcontaining additive the composition of the additive was studied on an x-ray innov-x systems instrument and an x’ pert mpd pro (panalytical) diffractometer. the infrared spectra of the sample were obtained on a bruker tensor ii ir fourier instrument. preparation of modified bitumen and study of its main properties to carry out the modification of bitumen, the method of physical mixing in one stage was used. table 2 physical properties of the additive physical properties value silicon content 20,06 appearance bulk mass color light gray solubility in water not soluble mass fraction of moisture, % no more 3,5 the base bituminous binder was heated to a fluid state of about 160°c, the pet modifier was added in an amount of 4% in the constant mixing mode, and the sca was added for 10 min and continuously mixed for 3 h to complete the sample preparation. the amount of sca introduced was 5, 10, 20, 30, and 40%. the choice of this method is due to the advantage from a practical point of view (porto m. et al. 2019), as it is simple to implement and involves a single step using classic paving equipment. 199 journal of sustainable architecture and civil engineering 2023/1/32 to identify the potential for practical application of the silicon-containing additive, the physic chemical and performance properties of initial and modified bitumen were investigated. study of the composition and properties of bitumen to study the change in the compositions and properties of bitumen before and after modification, the methods simdist boiling point characterization/ distribution (astm d7169), high temperatures simulated distillation by gas chromatography. to study changes in thermochemical and physical parameters during heating of bitumen and its modified sample, the method of differential thermal (dta) and thermogravimetric (tga) analyzes were used, performed on a q-1000d derivatograph in air in the temperature range from 20 to 1000 °c. the dynamic viscosity and density of samples of initial and modified bitumen were evaluated at 100°c using a stabinger svm 3001 viscometer. study of the performance properties of bitumen studies of the penetration of bituminous binders were carried out according to standard methods in astm d-5, softening point (astm d36), ductility (astm d113). results and discussion study of the possibility of using sca as a bitumen modifier the main physical and chemical characteristics of sca are shown in fig. 2, 3 and table 3. this additive has a fine grinding, which determines its good adsorbing properties for bitumen. ref. code score scale factor chemical formula 96-810-4313 23 0.553 si 8.00 o 24.00 al 4.00 96-152-5556 8 0.410 o 81.08 a l8.00 si 28.00 fig. 2 x-ray diffraction pattern of a silicon-containing additive sample table 3 xrd analysis of sca fig. 3 ir spectrum of coke production ash sca on the diffraction pattern, the silicon-containing additive (fig. 2) is presented as a predominantly amorphous phase, as evidenced by broad peaks in the range. x-ray phase analysis revealed a high content of silica and aluminum, which is confirmed by the results of x-ray fluorescence analysis (table 4). the ir spectrum of coke ash (fig. 3) contains peaks related to methylene and aromatic functional groups, and the presence of absorption bands in the range of 1100-100 cm-1, characteristic of si-o-si, bands in the 665 670 cm-1 can probably be attributed to the content of sic6h5. the presence of metal oxides in the composition of the sca will have an activating effect on the formation of structure in bitumen and positively affect the ability of bitumen to adhere to the mineral substrate. in this regard, it was decided to use this additive a waste product of the coke industry as a modifier for polymer bitumen binders. journal of sustainable architecture and civil engineering 2023/1/32 200 element content, % si 20.06 fe 9.90 al 13.96 ni 1.48 cu 0.35 zn 4.28 ca 5,40 pb 1.34 nb 0.37 mg 0.54 pd 1.44 ag 2.47 cd 2.04 sn 2.32 sb 2.05 remain 32.00 table 4 content of metals in sca study of the composition and properties of modified pmb the influence of the sca on the properties of the modified bitumen are presented in tables 5, 6 and fig. 4. table 5 represents the results of the distillation temperature distribution by the simulated distillation and gas chromatography (gc) method, which separates the individual hydrocarbon components in the order of their boiling points (villalanti d.c. et al. 2006). the results show that the introduction of sca into the composition of the bitumen polymer leads to an increase in the initial boiling point of the binder, which is caused by the weighting of the bitumen from c25 to c28. when comparing the thermal curves of the decomposition of bitumen samples (fig. 4), there is a difference in the kinetics of their oxidation in the temperature range of 210–900°c. on the example of thermogravimetric curve readings in the specified interval, a significant change in the weight loss mode of the sample without sca is observed, losing most of its mass (72.7%), for modified bitumen with sca, the weight loss decreases to 48.7%, which is consistent with the results of table 5. according to the results of the study of the composition and properties of bitumen before and after the introduction of sca, it can be concluded that with an increase in the content of the additive in bitumen, an improvement in the thermal stability of bitumen is noted, as well as a weighting of its composition. sample initial 5% 10% 20% 30% 40 % boiling point, с 401 403,7 405,8 408,3 418,6 429,6 fraction 1% 425 433,6 435,5 440,9 451,9 455,3 the amount of carbon at the start of boiling с25 с25 с25 с26 с27 с28 table 5 results of hightemperature simulated distillation of bitumen samples property initial pet sca content, % 5 10 30 40 viscosity, mpa*s 3463,7 3894,4 8968,7 11278,0 12946,0 13782,0 density, g/cm3 0,9559 0,9762 0,9890 1,0057 1,0098 1,0134 table 6 study of the physical and chemical characteristics of bitumen before and after modification the results of the table 6 shows that the viscosity is related to the content of sca in bitumen, therefore, the introduction of waste significantly increases the resistance to deformation of bitumen, since high viscosity is an indicator of high resistance to flow (escobar-medina et al. 2021). escobar-medina et al. (2021) believe that an increase in viscosity is achieved due to the physicochemical composition of the modifier, its texture and surface area, because of which a network of fibers is formed throughout the bitumen matrix. the data in table 6 indicate that starting from a concentration of 5 wt. % viscosity more than doubles; therefore, our applied waste is also able to form a local network structure, serve as a support, reinforcing the bitumen matrix and improving its resistance to deformation. with an increase in the amount of sca, an increase in viscosity is noted, however, it is important to remember that supersaturation with this additive is possible and the formation of large agglomerates characterized by negative properties in the asphalt mix. thus, in work of caro et al. (2016) it was found that at elevated concentrations of the additive, interaction between the fibers is induced, which leads to increased fragility of asphalt concrete mixtures. 201 journal of sustainable architecture and civil engineering 2023/1/32 fig. 4 derivatogram of a sample of the bitumen: a – original; b – polymer modified bitumen in the amount of 4 %; c – polymer modified bitumen with the addition of sca in the amount of 5% (a) (b) (c) an increase in viscosity and density may also indicate an increase in the content of aromatic components in bitumen (jiang et al., 2020), which certainly has a positive effect on the cohesive strength of the binder. however, it should be noted that the ir spectra show no changes in the functional groups after the introduction of the sca, which indicates the interaction of the additive and bitumen through physical adsorption. zhou et al. (2011); liu (2009) think that in polymer-modified bitumens, the stabilizer improves the stability of heat preservation due to the formation of a stable adsorption layer at the interface between the bitumen and polymer phases. table 7 data indicates a decrease in penetration by about 20% with the introduction of sca in an amount of 5%. with an increase in the concentration of sca, the value of penetration decreases, which indicates an increase in the stiffness and hardness of the bitumen. it is known (jeffry et al. journal of sustainable architecture and civil engineering 2023/1/32 202 2018) that high stiffness leads to low susceptibility to high temperature. according to brown et al. (2009), bitumen exhibits high resistance to cracking at penetrations above 30 mm when properly mixed and compacted. according to the results of table 7, it can be seen that because of the introduction of sca, an increase in the ductility values of the modified bitumen is observed, so for a sample with a content of 5% sca, a value of 40 mm is reached. however, as the concentration of the additive increases, a decrease in the values of plasticity is noted. the authors of jeffry et al. (2018) attribute this to an increase in the adhesion of bitumen, which is caused by the formation of a strong bond between bitumen and the additive. property value pet 5 10 20 30 40 needle penetration depth, 0,1 mm at 25 °с 62 49 46 41 40 38 ductility, mm 38 40 39 34 33 30 softening point, °с 56 59 60 62 63 64 table 7 change in the main properties of bitumen with the addition of sca the softening temperature of bitumen after the introduction of sca for 5% increased by 3 °c, with an increase in the concentration of introduced sca, an increase in this indicator is observed. a high softening temperature indicates that bitumen can withstand a certain temperature level before the transition from solid to liquid phase (jeffry et al., 2018). according to the data obtained, the addition of sca increases the softening point, provides a low sensitivity of the modified bitumen to temperature. the authors of martínez-anzures et al. (2018) believe that the addition of mineral additives according to stokes’ law can have a positive effect to reduce the difference between the densities of the continuous and suspended phases and increase the viscosity of the system, which improves the aging properties of the bituminous binder at high temperatures and provides improved stability. conclusions in the present work, we studied the possibility of using sca waste from the coke-chemical industry as a mineral additive for modifying polymer-bitumen binders. based on the research, it can be concluded that the modification of pmb during the introduction of sca is achieved through physical interaction, and increased rigidity and temperature resistance, which together indicates their improved performance properties, characterizes the resulting bitumen. the optimal concentration of the introduced additive was 5%, the increase of which will not lead to significant changes in the physical and operational characteristics of the binders. we hope that the resulting binders based on waste will solve the problems of using pmb technologies in the road industry, while meeting the requirements of sustainable development. this is achieved by using a significant amount of industrial waste as secondary raw materials, processing them into a new product using energy-saving technology, which reduces the consumption of natural resources and prevents the formation of hazardous substances and accidents. acknowledgment this research has been funded by the science committee of the ministry of education and science of the republic of kazakhstan (grant no. ар09259187 «development of an innovative way of using hard-to-use household waste in the production of environmentally friendly building materials»). 203 journal of sustainable architecture and civil engineering 2023/1/32 aatheesan, t., arulrajah, a., newman, g., bo, m.w., & wilson, j. 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(2014). polymer modification of bitumen. advances and challenges, 1838. https://doi.org/10.1016/j.eurpolymj.2014.02.005 about the authors yelubay madeniyet candidate of science (catalysis), associate professor toraighyrov university, department of chemistry and chemical technology main research area catalysis, petrochemistry, oil and gas processing, processing and disposal of industrial waste, environmental protection, processing of waste oils address lomov str., 64, pavlodar, republic of kazakhstan, 140008 tel.: +77056124252 e-mail: madik_chimik@mail.ru gulzat aitkaliyeva phd, associate professor satbayev university (k.satbayev kazakh national research technical university), department of geology, oil and mining main research area the extraction and transportation of oil, the processing and recycling of industrial wastes, the protection of the environment and obtaining new materials based on them address satbayev 22, almaty, republic of kazakhstan, 050013 tel. +7 7071225811 e-mail: g.aitkaliyeva@satbayev. university, gulzat_slyashevna@mail.ru danutė vaičiukynienė dr. professor kaunas university of technology main research area synthetic zeolites, special building mixes, use of waste materials in geopolymer materials of cement systems, alkaline activated materials address studentu str., 48, kaunas, lithuania, lt-51367 tel.: +37065766815 e-mail: danute.vaiciukyniene@ktu.lt aigul amitova phd, head of department satbayev university (k.satbayev kazakh national research technical university), department of geology, oil and mining main research area synthesis of thermosensitive polymers, hydrogels, production of new materials from production waste address satbayev 22, almaty, republic of kazakhstan, 050013 tel. +7 7012042408 e-mail: a.amitova@satbayev.university aiganym ismailova phd, associate professor international educational corporation (kazgasa), department of building technologies, infrastructure and management main research area synthesis of new multi-purpose materials, synthesis of building materials based on industrial materials address ryskulbekova st 18, almaty, republic of kazakhstan, 050043 tel.: +77001987717 e-mail: i-smile@list.ru gulnaz ibraimbayeva candidate of technical sciences, associate professor international educational corporation (kazakh leading academy of architecture and civil engineering) main research area the development of composition and technology, the study of the properties of building materials address ryskulbekova st 18, almaty, kazakhstan, 050043 tel.:+7701-172-60-20 e-mail: gulnazik1971@mail.ru this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 59 darnioji architektūra ir statyba 2013. no. 3(4) journal of sustainable architecture and civil engineering issn 2029–9990 investigation of width of vertical cracks in reinforced concrete box-girder viaducts saulius zadlauskas1*, mindaugas augonis1 and laimonas krašauskas2 1kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania 2se “transport and road research institute”, i. kanto g. 25, p.o. box 2082, 44009 kaunas, lithuania *corresponding author: saulius.zadlauskas@stud.ktu.lt http://dx.doi.org/10.5755/j01.sace.3.4.3277 the article examines the effect of dynamic loads on crack width of decks of prestressed reinforced concrete frame (boxgirder) viaducts. the experimental measurement of the changes in width of vertical cracks of pareizgupis viaduct resulting from the loads of moving heavy weight vehicles was made. during testing, four-axle vehicles with weights of around 40 tonnes were used and they were driven over the viaduct deck at the speed of 20–40 km/h. the stresses in prestressed reinforcement were analysed, calculated and compared to the results obtained during testing. having evaluated theoretically the elastoplastic operation of concrete, the width of a vertical crack was measured in the middle part of the viaduct. keywords: stressed reinforced concrete, crack width, stresses, precompression, elastoplastic deformations. 1. introduction bridge structures are constantly affected by dynamic loads caused by transport flows. dynamic loads caused by moving heavy weight vehicles are one of the main problems for bridge designers. in some cases dynamic loads are more important than static loads especially when analysing the cracking of reinforced concrete bridges. investigators (hamed, e., frosting, y. 2004 and huang, d. z., wang, t. l., shahaway, m. 1993) note that the cracks in most stressed reinforced concrete bridges opened by the effect of dynamic loads and overloads. a lot of research has been done on the dynamic effect of heavy weight vehicles on uncracked prestressed concrete bridges with a double t cross-section. (li, c. y. 1996 and bruni et al. 2003), however little research has been carried out on the cracked box girder bridges. when cracks appear in the beams of box-girder bridges (viaducts), linear analysis of reinforced concrete structures describing the effect of static and dynamic loads becomes invalid (moghimi, h., ronagh, h. r. 2007) and it is necessary to apply nonlinear analysis of reinforced concrete structures when analysing the limit states of bridge safety and operational suitability. there are many bridges in lithuania that have a deck with stressed reinforced concrete box girders and double t girders. in the old (operated for 20–30 years) stressed reinforced concrete box girder bridges very common damage is the cracking of girder webs shear and normal sections. most of cracks and damage were found in stressed reinforced concrete frame box girder viaducts that had been operated for around 30 years. (augonis et al. 2012). dynamic loads in the bridges and especially viaducts of old construction designed according to the russian design code (ch-200, 1962, ch-365, 1967) have been evaluated insufficiently. this code states that dynamic coefficient should be calculated according to the length of a bridge span not taking into account the possibility of deterioration of roadway pavement, pits and deck deformations (deflections) during bridge operation. the experimental research on dynamic and static deflections of road pavement roughness of the three viaducts (babtai, gėluva and pareizgupis) carried out by the authors (zadlauskas, s., augonis, m. 2012) showed that dynamic deflection and dynamic coefficient depended greatly on road pavement roughness. dynamic coefficient of the viaducts with uneven roadway surface was 20–30% higher than that of the viaducts with even roadway surface. dynamic coefficient is a very important parameter when calculating cracking moment of a structure as the deflection also. investigators (gomez navaro and lebet, 2001) note that due to the increase of cyclic loads that are formed when heavy weight vehicles move over a bridge, normal cracks open up in the tensile concrete zone. analyzing the cracking of double t and box girders under the loads of heavy weight vehicles, the scientists (sasaki et al. 2010) noticed that shear cracks open in the webs of double t girders due to more intensive transport flows. 60 this article analyses the vertical cracks opened up in the 5th segment of middle span of the pareizgupis viaduct (fig. 1), discusses the effect of dynamic loads on the cracked girders and presents experimental measurement of the changes in width of vertical cracks. when evaluating the elastoplastic operation of concrete (according to the nonlinear analysis of reinforced concrete structures), the stresses of prestressed reinforcement in a vertical crack zone have been calculated theoretically. 2. the experimental measurements of normal cracks width variation the pareizgupis viaduct has shear cracks (marked in green) and vertical cracks (marked in red) opened up in the middle segments (5 and 6, fig. 2) of girder b of the middle span. the viaduct has been designed according to the russian design code (ch-200, 1962, ch-365, 1967) which stated that the crack forming in the deck girders of reinforced concrete bridges was not allowed. it was found out during the inspection of viaduct structure that stressed tendons were highly affected by corrosion and some wire bunches were broken in the 5th segment of girder “b” (in the location of vertical cracks) (fig. 3). there are 24 high-strength stressed wire bunches at the bottom of this girder with the total cross-sectional area of 113 cm2. having inspected in detail these wire bunches, it was determined that 2.5 wire bunches were broken and 2 wire bunches were greatly subject to corrosion and were released. more than 300 heavy weight vehicles move over this viaduct per day and they affect corroded tendons additionally. in order to examine the effect of dynamic loads on the viaduct deck (especially in the cracked girder “b”), the changes in width of vertical cracks under the loads of heavy weight vehicles moving over a deck have been measured experimentally. testing was conducted in april 2011. the changes in width of vertical cracks were measured in the place of stressed reinforcement by electronic and mechanical sensors (fig. 4). the widths of opened up cracks were measured before the arrangement of sensors: the width of the first crack was 0.35 mm (60 mm measurement base), the width of the second crack was 0.40 mm (35 mm measurement base), the width of the third crack was 0.50 mm (56 mm measurement base). the changes in width of viaduct vertical cracks were measured using a four-axle vehicle with the weight of around 40 tonnes and it was driven over the viaduct deck in the speed of 30 km/h. the experimental measurements of the changes in width of vertical cracks are presented in table 1. the experimental measurements of the width changes of the second vertical crack were chosen for more detailed analysis of viaduct deck cracking. this change in crack width was measured by an electronic sensor and a mechanical indicator (precision of 0.01). they produced the same results. fig. 1. the pareizgupis viaduct plan, segment numeration and cross section in meters fig. 2. girder “b”of the pareizgupis viaduct in klaipėda direction. opened vertical and shear cracks 61 3. experimental results and their analysis when the corrosion of prestressed reinforcement and the elastoplastic operation of cracked concrete part were evaluated, the width of vertical crack and stresses in stressed tendons were calculated theoretically. having evaluated the initial crack width and the change in crack width obtained during testing, the width of a vertical crack is calculated according to the following formula: www initial,ktotal,k ∆+= (1) it was obtained that fig. 4. experimental measurement of the changes in width of vertical cracks table 1. experimental measurement of the changes in width of vertical cracks test number number of axles weight of a vehicle, t speed of movement km/h change in width of 2 crack ∆w, mm change in width of 3 crack ∆w, mm 1 4 40 30 0.07 0.09 2 4 40 30 0.06 0.07 3 4 40 30 0.06 0.07 4 4 40 30 0.07 0.08 5 4 40 30 0.07 0.07 average 4 40 30 0.066 0.07 the experimental measurements of the width changes of the second vertical crack were chosen for more detailed analysis of viaduct deck cracking. this change in crack width was measured by an electronic sensor and a mechanical indicator (precision of 0.01). they produced the same results. 3. experimental results and their analysis when the corrosion of prestressed reinforcement and the elastoplastic operation of cracked concrete part were evaluated, the width of vertical crack and stresses in stressed tendons were calculated theoretically. having evaluated the initial crack width and the change in crack width obtained during testing, the width of a vertical crack is calculated according to the following formula: www initial,ktotal,k δ+= (1) it was obtained that mm.w total,k 470= . according to the snip method, the long-term vertical crack width of ~0.4mm under the self weight is obtained when ~7-8 wire bunches do not operate in the crosssection. the effects of cyclic and dynamic loads, which are very important in bridges and viaducts, are not evaluated in this case. it has to be noted that the diameter of a wire bunch, which is reduced in proportion to the amount of corroded reinforcement, has a great influence in these calculations. if approximately 4-5 wire bunches would not operate in the cross-section (which was found during the visual inspection), the long-term width of a vertical crack (not evaluating cyclic and dynamic loads) is equal to ~0.17 mm, i. e. almost two times less than it was obtained during the inspection. contrary results were obtained by calculating crack width under the load of a vehicle (~40 t) standing on one girder, which produces the additional bending moment of 1.079 mnm in the cross-section. in this case, we obtain that the experimental short-term value of vertical crack width will be reached when 1.5 wire bunches will not operate. on the ground of practical measurement notice it can be accepted that around 20% of load on one girder move to the adjacent girder over a diaphragm. in this case, the crack of mentioned size would be formed when ~4-5 wire bunches are not operating. more detailed examination of the increase in stresses of both cases showed that they were equal to ~40mpa. the dependence of the change in width of vertical crack on the cross-sectional area of stressed reinforcement (evaluating the fact that load of moving heavy weight vehicle is carried by 1 or 2 or 1.2 girders) is presented in figure 5. using the experimental values relative deformations in stressed tendons are calculated as follows: 0020.l/l == δε (2) having calculated tensile stresses in stressed tendons under the loads of heavy weight vehicles (not evaluating the effect of tensile concrete) according to the relative deformations, we obtain: mpa.e ss 3601800000020 =⋅=⋅= εσ . thus, the obtained value differs from the calculated value by 9 times. in order to check the accuracy of results, the increase of stresses in reinforcement only under a transport load (not taking into consideration the operation of tensile concrete) was calculated additionally (fig. 6). the first crack (1) the second crack (2) the third crack (3) . according to the snip method, the long-term vertical crack width of ~0.4mm under the self weight is obtained when ~7-8 wire bunches do not operate in the cross-section. table 1. experimental measurement of the changes in width of vertical cracks test number number of axles weight of a vehicle, t speed of movement km/h change in width of 2 crack δw, mm change in width of 3 crack δw, mm 1 4 40 30 0.07 0.09 2 4 40 30 0.06 0.07 3 4 40 30 0.06 0.07 4 4 40 30 0.07 0.08 5 4 40 30 0.07 0.07 average 4 40 30 0.066 0.07 fig. 3. the general view of corroded tendons in the location of opened vertical cracks fig. 4. experimental measurement of the changes in width of vertical cracks 62 the effects of cyclic and dynamic loads, which are very important in bridges and viaducts, are not evaluated in this case. it has to be noted that the diameter of a wire bunch, which is reduced in proportion to the amount of corroded reinforcement, has a great influence in these calculations. if approximately 4-5 wire bunches would not operate in the cross-section (which was found during the visual inspection), the long-term width of a vertical crack (not evaluating cyclic and dynamic loads) is equal to ~0.17 mm, i. e. almost two times less than it was obtained during the inspection. contrary results were obtained by calculating crack width under the load of a vehicle (~40 t) standing on one girder, which produces the additional bending moment of 1.079 mnm in the cross-section. in this case, we obtain that the experimental short-term value of vertical crack width will be reached when 1.5 wire bunches will not operate. on the ground of practical measurement notice it can be accepted that around 20% of load on one girder move to the adjacent girder over a diaphragm. in this case, the crack of mentioned size would be formed when ~4–5 wire bunches are not operating. more detailed examination of the increase in stresses of both cases showed that they were equal to ~40mpa. the dependence of the change in width of vertical crack on the cross-sectional area of stressed reinforcement (evaluating the fact that load of moving heavy weight vehicle is carried by 1 or 2 or 1.2 girders) is presented in figure 5. using the experimental values relative deformations in stressed tendons are calculated as follows: 0020.l/l == ∆ε (2) having calculated tensile stresses in stressed tendons under the loads of heavy weight vehicles (not evaluating the effect of tensile concrete) according to the relative deformations, we obtain: mpa.ess 3601800000020 =⋅=⋅= εσ . thus, the obtained value differs from the calculated value by 9 times. in order to check the accuracy of results, the increase of stresses in reinforcement only under a transport load (not taking into consideration the operation of tensile concrete) was calculated additionally (fig. 6). fig. 6. the design scheme of stresses in reinforcement not taking into consideration the operation of tensile concrete the tension stiffening was not evaluated for the reason of small measurement base. the space between cracks is ~500 mm and measurement base – 40 mm. so, the influence of tensile concrete would not affect the result significantly. stresses in reinforcement are equal to ~100 mpa not taking into consideration the effect of a diaphragm and ~80 mpa when evaluating the effect of a diaphragm. therefore, we cannot evaluate the state of stresses in reinforcement on the ground of the width of short-term crack determined experimentally. it has to be noted that the calculations of crack width were also made in the interval in which the crack cannot open up theoretically; thus, the produced results cannot be totally accurate. the increase of stresses in reinforcement of ~300 mpa theoretically is obtained when 7–8 wire bunches are broken (in the examination of girder 1) under the total bending moment of 7,659 mnm (from a decking and a truck). fig. 5. the dependence of vertical crack width on the cross-sectional area of stressed reinforcement 63 4. conclusions ▪ having performed the experimental measurements of the changes in width of vertical cracks of the pareizgupis viaduct under the loads of moving heavy weight vehicles, it was found out that the crack width increased by around 0,066 mm. ▪ it is not possible to evaluate the potential level of prestressed reinforcement corrosion based on the width of long-term vertical crack determined experimentally because cyclic and dynamic loads are of great importance in this case. ▪ on the ground of the width of short-term vertical crack determined experimentally, the potential level of prestressed reinforcement corrosion was calculated theoretically. it was obtained that, after evaluating the possible effect of a diaphragm in the section, 4–5 wire bunches do not operate, which was found out during the inspection. references augonis, m., zadlauskas, s., rudžionis, ž., pakalnis, a. 2012. the analysis of reinforced concrete box-girder viaduct defects and their estimation. the baltic journal of road and bridge engineering 7 (1), 13–21. http://dx.doi.org/10.3846/bjrbe.2012.02 bruni, s., beretta, m., bocciolone, m., 2003. simulation of bridge heavy road vehicle interaction and assessment of structure durability. international journal of vehicle design 20 (1), 70–85. ch 200-62. technical design conditions of reinforced concrete motorway and town bridges and overflows (технические условия проектирования желез нодорожных автодорожных и городских мостов и труб). моsсow, 1962, 190 p. (in russian). ch 365-67. design regulations for the structures of reinforced concrete and concrete bridges and overflows (указания по проектированию железобетонных и бетонных конструкций мостов и труб) моsсow, 1967, 147 p. (in russian). gomez navaro, m., lebet, j. – p. 2001. concrete cracking in composte bridges: tests, models and design proposals. struct. eng. int. (iabse, zurich, switzerland), 11 (3), 184– 190. hamed, e., frosting, y. 2004. free vibrations of cracked prestressed concrete beams. journal of engineering structures (26), 1611–1621. huang, d. z., wang, t. l., shahaway, m. 1993. impact studies of multigirder concrete bridges. journal of structural engineering 119 (8), 2387–4020. http://dx.doi.org/10.1061/(asce)0733-9445(1993)119:8(2387) li, c. y. 1996. bridge vibration and impact under moving vehicles. in proceedings of the 1996 3rd joint conference on engineering systems design and analysis 81 (9), 17–23. sasaki, k. k., peret, t., araiza, j. c., hals, p. 2010. failure of concrete t-beam and box-girder highway bridges subjected to cyclic loading from traffic. journal of engineering structures (32), 1838–1845. zadlauskas, s., augonis, m. 2012. the infuence of dynamic loads on prestressed concrete box-girder viaduct deflection. in: proceeding of 17th internanional conference mechanika 2012, kaunas lithuania, 345–350 received 2013 01 31 accepted after revision 2013 05 20 saulius zadlauskas – ph.d. student at kaunas university of technology, faculty of civil engineering and architecture, department of building structures. main research area: durability of engineering structures, static and dynamic research of bridges. address: kaunas university of technology, faculty of civil engineering and architecture, department of engineering structures, studentu st. 48, lt-51367. tel.: +370 37 300473 e-mail: saulius.zadlauskas@stud.ktu.lt mindaugas augonis – associated professor at kaunas university of technology, faculty of civil engineering and architecture, department of building structures. main research area: durability of engineering structures, strength and stability of reinforced concrete structures. address: kaunas university of technology, faculty of civil engineering and architecture, department of engineering structures, studentu st. 48, lt-51367. tel.: +370 37 300473 e-mail: mindaugas.augonis@ktu.lt laimonas krašauskas – chief of department of bridges research. main research area: static and dynamic research of bridges. address: i. kanto st. 25, p.o. box 2082, 44009 kaunas, lithuania. tel.: +370 37202390 e-mail: l.krasauskas@tk 67 lightweight concrete with aggregates made by using industrial waste diana bajare, janis kazjonovs*, aleksandrs korjakins riga technical university, faculty of civil engineering, kalku st. 1, lv-1658, riga, latvia. *corresponding author: janis.kazjonovs@rtu.lv http://dx.doi.org/10.5755/j01.sace.4.5.4188 the disposal and treatment of solid and hazardous industrial waste is quite expensive for any industry; therefore it brings challenges to find a solution that permits to obtain new, usable products by waste utilization in a technically and economically sustainable as well as environmentally friendly way. the production of lightweight concrete by using aggregates made by industrial by-products and hazardous solid waste such as expanded fly ash, slag, sludge etc. is well known. this research provides possibilities to reuse waste called nonmetallic product (nmp) from aluminium scrap recycling factories for the manufacturing of lightweight expanded clay aggregates and lightweight concrete. characterization of nmp is described in the preliminary publications (bajare et al. 2012). the manufacturing cycle of lightweight expanded clay aggregates were simulated in laboratory by sintering the clay waste mixes in the rotary furnace up to 1200°c. lightweight expanded clay aggregates with rather different pore structure were obtained due to slight variations of mixture composition and sintering temperature. produced aggregates were with bulk density from 320 kg/m3 to 620 kg/m3. different types of lightweight aggregates were used to produce lightweight concretes. mechanical, physical and thermal conductivity tests were performed for hardened concrete specimens according to standard procedures. keywords: lightweight concrete, expanded clay aggregate, industrial waste. 1. introduction lightweight aggregates are granular and porous materials with a bulk density in a range of 280 kg/m3 to 1100 kg/m3, depending on the type and grading size (owens, 1993). for their low density, good thermal and acoustic insulation, and good fire resistance properties, lightweight aggregates have become a focus of interest. they are an essential component in a variety of building materials such as prefabricated structural units, lightweight concretes, especially in high-rise buildings, as well as track ballasts and road coatings, along with bituminous materials and other geotechnical applications (babu and babu, 2004). lightweight concrete can be defined as the product resulting from the binding of lightweight aggregate particles or fragments with a binder, usually artificial cement, and water. the term lightweight concrete is used for concrete with a density of less than 1800 kg/m3 (mehta and monteiro, 2006). quite often, the aggregates comprise the weakest component within the concrete. the greater the aggregate strength and density, the higher will be the concrete strength. factor like the water–cement (w/c) ratio also has a great influence on the concrete properties (short and kinniburgh, 2007). when the water/cement ratio of concrete increases, the number of pores within the cement paste and in the aggregate/cement paste interfacial zone increases as well. an increase in pore numbers within the cement paste and in the aggregate/cement paste interfacial zone leads to a corresponding decrease in concrete strength (tommy and tang, 2007). the disposal and treatment of solid and hazardous industrial waste is quite expensive for any industry, therefore it brings challenges to find a solution that permits to obtain new, usable products by waste utilization in a technically and economically sustainable as well as environmentally friendly way. the production of lightweight concrete by using aggregates made by industrial by-products and hazardous solid waste such as expanded fly ash, slag, sludge etc. is well known (naik and moricioni, 2006; gonzálezcorrochano et al. 2011; shinzato and hypolito, 2005). in study lightweight aggregate was sintered by incorporation of sludge which was a gas former to the mixture of clay that is conformed in spherical form and heat treated at high temperatures around 1100-z°c (pinto et al. 2004). the voids are generated by the combustion or gasification of the waste included in mass of the aggregate. this research provides possibilities to reuse waste called non-metallic product (nmp) from aluminium scrap darnioji architektūra ir statyba 2013. no. 4(5) journal of sustainable architecture and civil engineering issn 2029–9990 68 recycling factories for the manufacturing of lightweight expanded clay aggregate and lightweight concrete. the consumption of aluminium waste is rising continuously worldwide, which is great stimulus for developing a nonwaste technology (shen and forssberg, 2003; lucheva et al. 2005; samuel, 2003). this work is based on a previous research, where investigation on how the type of clay, the type and amount of nmp and the sintering temperature affect the properties of the sintered lightweight aggregate. it was concluded that the maximum expansion temperature of lightweight aggregate increases proportionally to a higher amount of the nmp proportion in the clay composition, i.e., every composition has its own maximum expansion temperature. the nmp here was considered as foaming agent (lvs, 2002). the goals of this experimental work are: 1) to produce lightweight aggregate of nmp and clay in a laboratory rotary kiln in different sintering temperatures; 2) to produce lightweight concrete by using them. the mechanical, physical properties for the produced aggregates and lightweight concrete will be analyzed as well. 2. methods raw materials in the current study lightweight expanded clay aggregates and nmp from aluminium scrap recycling factories in different compositions. the chemical composition of clay and nmp was determined according to lvs en 196-2 with the sensibility of ±0.5 wt% (table 1) (bajare at al. 2012).were produced from clay with a high content of carbonates. table 1. basic chemical composition of clay and nmp (wt%) clay nmp ignition loss, 1000°c 13.60 6.21 al2o3 14.34 63.19 sio3 50.22 7.92 cao 8.54 2.57 so3 0.07 0.36 tio2 0.56 0.53 na2o 0.43 3.84 k2o 3.09 3.81 mgo 3.07 4.43 fe2o3 5.74 4.54 others >2.60 the x-ray diffraction analysis (xrd) was used for determination of changes in the mineralogical composition of nmp during the heat treatment. according to the xrd of nmp, the following toxic impurities were eliminated by heat treatment at the temperature of 1100°c: aluminium nitride (aln), iron sulphite (feso3) and aluminium chloride (alcl3) (table 2). emissions of gases (the smell of ammonia was detected) during high-temperature treatment of nmp are used as initiator to create an extra porous structure of the sintered ceramic bodies. the clay with high carbon content was mixed with nmp in two different proportions. obtained compositions were named la and lb, corresponding to 9.1% and 23.1% of nmp by weight, respectively. this kind of selection was on the basis of the previous investigations (bajare at al. 2012). table 2. basic mineral composition of clay and nmp clay nmp nmp (treated at 1100°c) sio2 al2o3 al2o3 caco3 fealo3 feal2o4 kal2(si3alo10)(oh)2 mgal2o4 mgal2o4 na(k)alsi3o8 sio2 α-sio2 al2si2o5(oh)4 al sio2 camg(co3)2 feso3 aln alcl3 al(oh)3 production of lightweight expanded clay aggregates the clay and nmp mixtures were milled and homogenized with planetary ball mills. the particle size of the mix was determined by particle size analyzer zetaplus. effective diameter of mix was 54 µm, median diameter – 8.7 µm, but mean diameter – 11.3 µm. a controlled amount of water of 20 – 25% was added to the homogenized mixtures. green pallets with a spherical shape and diameter from 5 to 10 mm were prepared by granulating technique. next step was the drying process in room temperature for 24 h and, subsequently, dried in an oven at 105°c for 48 h. fig. 1. melting behavior of the base powder mixture la and lb prior to sintering the dry pallets in laboratory rotary kiln, determination of the melting behavior of the base powder mixture la and lb using hesse® heating microscope was done (fig. 1). the heating rate till 500°c was 80°c/min, but till 1350°c – 15°c/min. it has results in the rotary kiln indicated that the sintering starts at a temperature, which is 20 – 30°c lower than determined in the heating microscope. the temperature for the kiln was set to 1180°c for both 69 aggregate compositions. the mixture la in this temperature expanded more than mixture lb sintered in the same temperature. it can be concluded that in the same temperature with less nmp content in the mixture, lightweight expanded clay aggregate with lower density can be obtained. sintering of the pallets was carried out in a rotary kiln made by the heat treatment equipment company keramserviss (fig. 2). the length of the tube is 200 cm, its internal diameter – 6.7 cm. the rotary kiln has three zones with a thermocouple in each, where the central zone is with the highest temperature. the temperature can be set manually by the user. the pallets in the kiln were placed in a continuous flow by using special equipment. in the entering zone the pallets were gradually heated to the sintering temperature to avoid their damage and uneven pore distribution. the whole sintering process ranged from 10 to 15 minutes until the necessary viscosity was achieved to generate and trap the gases inside the lightweight expanded clay aggregate. due to the rotating speed 20 rpm and the constant kiln incline of 1°, the granules moved through all heating zones. the produced granules where from 4 to 11.2 mm in diameter. fig. 2. laboratory rotary kiln for lightweight aggregate production lightweight concrete design in order to obtain comparative data, the experimental lightweight concrete was produced by using both laboratory produced lightweight aggregates la and lb and commercially available a1, a2 and b1. ordinary portland cement cem i 42.5 n was used as a binding agent. sand from 0–4 mm was used as an additional aggregate for better particle distribution in the concrete composition. in some compositions undensified commercial silica fume product (sf) elkem microsilica 971u was used. concrete compositions were produced with the water cement ratio of 0.46. the first one was designed with a cement content of 348 kg/m , where the main variable in the concrete composition was lightweight expanded clay aggregate, la, a1, a2, lb and b1 and was marked with a prefix c before the aggregate marking. concrete compositions with aggregates la, a1 and a2 were named as low strength concrete. concrete compositions with aggregates lb and b1 were named as high strength concrete accordingly. the second concrete composition was produced with an increased amount of cement – 425 kg/m3, sf, additional admixture superplasticizer and varied with aggregates lb and b1. they were named as high strength lightweight concrete with silica fume and were marked with a prefix cc before the aggregate marking. the lightweight expanded clay aggregates were used in a pre-wetted condition so that water content in the cement paste does not change by water absorption of the aggregates. concrete compositions are summarized in table 3. concrete compositions were mixed with high speed paddle mixer according to the following procedure: first, dry components were mixed for 1 minute, then 2/3 of water amount was added and mixed for 1 minute. during the next step of mixing the remaining water was incorporated together with admixtures. to determine the mechanical and physical properties concrete specimens (4 × 4 × 16 cm) were prepared by using steel moulds. consolidation was done by using vibrating table. nine specimens were prepared for each composition. the specimens were cured in curing room. the compressive and flexural strength was determined at the age of 3 and 28 days according to en 12390. the tests were performed 24 h after the specimens were removed from the curing room. physical properties, like water absorption and bulk density, were determined after 28 days. table 3. the amount of materials for 1m3 of concrete mixture, kg low strength lightweight concrete high strength lightweight concrete high strength lightweight concrete with silica fume materials cla ca1 ca2 clb cb1 cclb ccb1 portland cement cem i 42.5 n 348 348 348 348 348 425 425 sand (0 4 mm) 822 822 822 822 822 829 829 la 232 lb 445 341 a1 227 a2 230 b1 568 436 silica fume 55 55 admixtures superplasticizer 2 2 2 2 2 7 7 water 160 160 160 160 160 195 195 total 1564 1559 1562 1777 1900 1852 1947 3 70 the thermal conductivity of 30 × 30 × 5 cm thick plate specimens was measured using a heat flow meter (lasercomp® fox 600). the specimens were tested in airdry conditions. 3. results and discussion physical and mechanical properties of the lightweight expanded clay aggregates in order to compare the produced lightweight expanded clay aggregates la and lb with the commercially available alternatives, different lightweight concrete compositions containing different aggregates were prepared. commercially available lightweight expanded clay aggregates, named a1, a2 were compared with produced aggregate la and b1 with lb. the bulk density and particle density of aggregates were measured in accordance with en 1097-3 and en 1097-6. crushing strength was done by a standard method mentioned in gost 10268-80 for a relative comparison between the aggregates. the bulk, particle density and crushing strength for these aggregates are shown in table 4 and 5. bulk density of aggregates is ranging from 320 kg/m3 to 360 kg/m3, where the produced aggregate la has the lowest bulk density of 320 kg/m3 (table 4). higher difference between the aggregates is observed in crushing strength, where la has 0.81 mpa, but a1 and a2 has 1.36 mpa and 1.49 mpa, respectively. table 4. physical and mechanical properties of lightweight expanded clay aggregates bulk density, kg/m3 particle density, kg/m3 crushing strength, mpa la 321.1 600.0 0.81 a1 360.5 588.5 1.36 a2 362.2 594.2 1.49 lb has lower bulk density (620 kg/m3) comparing to the bulk density of aggregate b1 (830 kg/m3). aggregate b1 is with higher crushing strength of 12.21 mpa, where the produced aggregate lb has 4.21 mpa. the aggregate density is one of the main criteria, which is taken into account measuring the aggregate quality and thereafter its influence on the mechanical behavior of lightweight concrete. table 5. physical and mechanical properties of lightweight expanded clay aggregates bulk density, kg/m3 particle density, kg/m3 crushing strength, mpa lb 624.2 1154.2 4.21 b1 834.3 1471.7 12.21 water absorption for the aggregates was measured after 30 minutes, 1, 24 and 48 hours (en 1097-6). the results are shown in fig. 3. in the first 30 minutes aggregates absorb about 80% of the total amount of water absorbed in 48 hours. for commercially available aggregates a1 and a2 the water absorption after 48 hours (~18%) is higher than for the produced aggregate la (~12%). the produced aggregate lb showed lower water absorption after 48 hours (~9.5%) than b1 (~12%), which means that less additional water will be necessary to add in the concrete mixing process. fig. 3. water absorption of aggregates vs. time function fig. 4. low strength lightweight concrete specimen and aggregates la physical and mechanical properties of the lightweight concrete specimens density and water absorption of lightweight concrete specimens are shown in fig. 5 and 6. low strength concrete cla, ca1 and ca2 bulk density ranged from 1550 kg/m3 to 1600 kg/m3 (table 6). high strength lightweight concrete clb, cb1 and cclb samples showed bulk density under 2000 kg/m3, ranging from 1800 to 1920 kg/m3, but concrete composition ccb1 showed result 2020 kg/m3 (table 7). a clear trend was observed that lower bulk density concrete samples showed higher water absorption. for concrete cla, ca1, ca2, clb and cb1 water absorption varied from 7.5% to 8.6%, but for high strength lightweight concrete with sf the result was lower ranging from 4.3% to 4.6%. despite the fact that water absorption of lightweight aggregates a1 and a2 was almost two times lower, the influence to the concrete water absorption was insignificant (difference between cla and cla1, cla2 was 0.2%–0.3%). it might be explained by the pre-wetting of the lightweight aggregates, because in this case the free water in fresh concrete is not taken away by the aggregates, thereby not influencing the porosity and water absorption of concrete. 71 table 6. bulk density and water absorption of low strength lightweight concrete concrete composition bulk density, kg/m3 water absorption, % cla 1580 8.4% ca1 1670 8.6% ca2 1620 8.8% table 7. bulk density and water absorption of high strength lightweight concrete with and without sf concrete composition bulk density, kg/m3 water absorption, % clb 1800 7.5% cb1 1920 7.8% cclb 1890 4.3% ccb1 2020 4.6% the results of concrete compressive and flexural strength at 3 and 28 days are shown in fig. 7 and 8. comparing the aggregate crushing strength in table 4 and 5, it is concluded that the achieved level of concrete strength was directly proportional to the aggregates crushing strength as well as to the aggregate density. high strength concrete specimens with sf, cclb and ccb1 showed higher strength after 28 days than clb and cb1, respectively. however, it was lower after 3 days, which might be explained by higher admixture content delaying the hydration processes in cement paste and sf addition (it increases the final strength due to puzzolanic reactions). for concrete specimens clb and cclb with produced aggregate lb compressive strength after 28 days was 32 mpa and 43 mpa reaching 34 % increase. as it was expected, concrete specimens with a use of b1 as aggregate showed higher compressive strength after 28 days, where for concrete specimens cb1 and ccb1 it was 54 mpa and 62 mpa, reaching 15 % increase. the same trend was observed in flexural strength results, where for clb, cb1, cclb and ccb1 after 28 days it was 5.5 mpa, 6.7 mpa, 6.9 mpa and 7.6 mpa, respectively. in the production of low strength concrete specimens cla, ca1 and ca2 aggregates la, a1 and a3 were used. all specimens showed similar results in compressive strength after 28 days ranging from 20 to 24 mpa, and in flexural strength ranging from 4 to 5 mpa (fig. 6 and 7). there is no significant difference between mechanical properties of 3 and 28 days old specimens. thermal conductivity of low strength lightweight concrete specimens the thermal conductivity of 30 × 30 × 5 cm thick plate specimens was measured using a heat flow meter fig. 5. bulk density of lightweight concrete, kg/m3 fig. 6. water absorption of lightweight concrete 72 (lasercomp® fox 600). the specimens were tested in airdry conditions. thermal conductivity of the lightweight concrete is shown in table 8. it is seen that for all concrete cla, ca1 and ca2 samples the conductivity varies in the range from 0.31 w/mk to 0.33 w/mk. table 8. lightweight concrete thermal conductivity thermal conductivity, w/mk cla 0.315 ca1 0.327 ca2 0.311 4. conclusions lightweight aggregate with different density (from 320 kg/m3 to 620 kg/m3) and crushing strength (from 0.8 mpa to 4.2 mpa) can be produced by using laboratory rotary kiln with the identical sintering temperature of 1180°c and regime, but changing nmp amount in composition of fig. 7. compressive strength of lightweight concrete fig. 8. flexural strength of lightweight concrete raw materials. they can substitute commercially available lightweight aggregates in low and high strength lightweight concrete. laboratory sintered aggregates la and lb are with significantly lower water absorption up to 12% compared with the commercially available aggregates a1 and a2 (~18%). the water absorption for laboratory sintered aggregates is equivalent to high strength aggregates b1 (~12%). obtained concrete bulk densities ranged from 1600 kg/ m3 to 2020 kg/m3. hardened concrete bulk density for cla, ca1 and ca2 was from 1550 kg/m3 to 1600 kg/m3, therefore it was declared as lightweight concrete. high strength lightweight concrete clb, cb1 and cclb samples showed bulk density under 2000 kg/m3, but concrete composition ccb1 showed result 2020 kg/m3. concrete made with lightweight aggregates with lower crushing strength and bulk density showed lower mechanical properties. low strength lightweight concrete specimens cla, ca1 and ca2 showed similar results in compressive strength after 28 days ranging from 20 to 24 mpa, and in 73 flexural strength ranging from 4 to 5 mpa. compressive strength of high strength lightweight concrete clb and cb1 were 32 and 54 mpa after 28 days, and flexural strength were 5.5 and 6.7 mpa, respectively. additional sf and admixture improved the mechanical properties of cclb and ccb1, where compressive strength after 28 days were 43 and 62 mpa, and in flexural strength 6.9 and 7.6 mpa. acknowledgement the research work was carried out in the frame of the latvian council of science project: “development of sustainable effective lightweight construction materials based on industrial waste and local resources” (no. z12.0412). references babu k. g., babu d.s., cement and concrete composites 26; 2004, 605 p. bajare d., korjakins a., kazjonovs j., rozenstrauha i. pore structure of lightweight clay aggregate incorporate with nonmetallic products coming from aluminium scrap recycling industry. journal of the european ceramic society 32 2012, 141–148 p. gonzález-corrochano b., alonso-azcárate j., rodas m., barrenechea j. f., luque f. j. microstructure and mineralogy of lightweight aggregates produced from mining and industrial wastes. construction and building materials 25 2011, 3591–3602 p. lo. tommy y., tang w. c., cui h. z. the effects of aggregate properties on lightweight concrete. building and environment 42 2007, 3025–3029 p. lucheva b, tsonev t, petkov r. non-waste aluminium dross recycling. journal of the university of chemical technology and metallurgy 2005;40(4):335–8. mehta p. k., monteiro p. j. m. concrete, microstructure, properties and materials. new york: mcgraw-hill companies; 2006. naik t. r., moricioni g. environmental-friendly durable concrete made with recycled materials for sustainable concrete construction. milwaukee, 2006, 13 p. owens, p. l. 1993. lightweight aggregates for structural concrete. structural lightweight aggregate concrete, 1–18. pinto s., rosenbom k., machado v. m., labrincha j. a., ferreira v. m. incorporation of sludge in light expanded clay aggregates. key engineering materials, 2004, 1391–1394 p. samuel m. a new technique for recycling aluminium scrap. journal of materials processing technology 2003; 135(1):117–24. http://dx.doi.org/10.1016/s0924-0136(02)01133-0 shen h, forssberg e. an overview of recovery of metals from slags. waste management 2003; 23:933–49 p. shinzato mc, hypolito r. solid waste from aluminium recycling process: characterization and reuse of its economically valuable constituents. waste management 2005; 25:37–46. http://dx.doi.org/10.1016/j.wasman.2004.08.005 short a., kinniburgh w. lightweight concrete. 3rd ed. london: applied science publishers; 1978, 321 p. received 2013 04 23 accepted after revision 2013 10 29 diana bajare – dr. sc. ing., associated professor at the institute of materials and structures, faculty of civil engineering, riga technical university. main research area: hp and uhp concrete, lightweight concrete, geopolymer technology, ceramic, waste recycling in building materials, passive cooling systems, restoration of historical structures and others. address: kalku iela 1, lv 1658, riga, latvia. tel.: +371 29687085 e-mail: diana.bajare@rtu.lv janis kazjonovs – bsc. ing., technician at the institute of materials and structures, faculty of civil engineering, riga technical university. main research area: lightweight concrete, passive cooling systems, innovative building materials address: kalku iela 1, lv 1658, riga, latvia. tel.: +371 26590735 e-mail: janis.kazjonovs@rtu.lv aleksandrs korjakins – dr. sc. ing., professor at the institute of materials and structures, faculty of civil engineering, riga technical university. main research area: hp and uhp concrete, lightweight concrete, geopolymer technology, ceramic, waste recycling in building materials, passive cooling systems and others. tel.: +371 26422442 e-mail: aleks@latnet.lv 27 darnioji architektūra ir statyba 2014. no. 1(6) journal of sustainable architecture and civil engineering issn 2029–9990 complex model for assessment of ex-industrial building conversion options into lofts mindaugas daukšys1*, justas pilipavičius2, ala daugėlienė1 1*kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania 2jsc “lidl”, naugarduko str. 102, lt-03160 vilnius, lithuania. *corresponding author: mindaugas.dauksys@ktu.lt http://dx.doi.org/10.5755/j01.sace.6.1.6308 industrial decline and a changing real estate market have led to large numbers of industrial buildings becoming outdated, redundant or obsolete, implicating social and economic problems. a solution may be found through the conversion of abandoned industrial buildings into housing, as it is an attractive adaptation option, given the tight housing market in lithuania. now that loft apartments have become a trendy style of living, there are also barriers to lofts development, which invariably concern cost. therefore the loft conversion developers should perform complex analysis and versatile evaluation of ex-industrial building in order to determine the success of investment project. the objective of the research presented in this paper is to develop a complex assessment model for ex-industrial property conversion options. to that end, firstly a review of the literature is conducted to identify the existing lofts conversion practice and explore their social and economic feasibility. afterwards, a model for the assessment of non-residential property conversion options is presented. based to the theoretical assumptions and a study of the existing practice three alternatives are suggested and implicated in the multiple criteria evaluation: hard loft, new hard loft and soft loft. the findings of a certain case study investigation revealed the best option for ex-industrial building transformation into living space, providing the best financial benefit of investment project, so-called new hard loft. keywords: conversion, ex-industrial building, loft, real estate development. 1. introduction economic decline in lithuania and a changing real estate market have led to large numbers of industrial buildings becoming outdated, redundant or obsolete. obsolescence is perceived as a problem of economic and social decline. economically, a vacancy of building affects its owner directly. for society, an abandoned building presents problems of insecurity and social uncertainty and may bring about criminality ranging from vandalism and graffiti to break-ins, illegal occupancy and fires (remøy and voordt, 2007). at the same time such redundant buildings also have indirect effects through the negative image that they give to the surrounding area. a solution may be found through the conversion of abandoned industrial buildings into housing, as it is an attractive adaptation option, given the tight housing market in lithuania. adaptability as a mean of increasing usability and extending buildings functional lifespan has been discussed in architecture since the 1960s (remøy and wilkinson, 2012). it is broadly interpreted with definitions referring to “change of use”, maximum “retention” of original structure and fabric, and extending “useful life”. adaptation can occur “within use” and “across use”; for example, a factory building can undergo adaptation and remain a factory (within use adaptation) or it may change use to residential and be classed as “across use” adaptation (ellison and sayce, 2007). remøy and wilkinson (2012) analyzed sustainable adaptation of vacant office buildings and defined conversion, or fitting a new use to an existing building, as a form of sustainable development for buildings that have outlived their original use and become obsolete. they distinguished three drivers for buildings conversion to housing social, economic and environmental. social driver is the renewed appeal for city center living and planning policies that reinforce this interest. the economic reason for the interest in adaptation is the growing perception that old buildings are often cheaper to convert to new uses than to demolish and rebuild (coutts, 2012; bullen, 2007). these conversion projects will only be interesting to developers if they are economically feasible. the environmental importance of this trend is that extending the useful life of existing buildings supports the key concepts of sustainability by lowering material, transport and energy consumption and pollution. 28 the conversion of non-residential property such as factories, warehouses or office blocks into apartments have taken place across a wide range of cities in europe, north america, australia and asia (hamnett, 2009). this process was first identified in research papers of zukin (1982, 1989) in her analysis of the soho area of downtown manhattan. it involved the conversion of old industrial buildings in the former garment area into large, open plan residential ‘lofts’, often of 2000 square feet or more floor area. according to hamnett (2009) loft conversions can be seen as a specific physical form of central and inner city gentrification associated with the transformation of previous industrial and commercial urban uses to ‘post-industrial’ residential uses. the consequent demand for central and inner city residential property is very strong and it becomes profitable for developers to convert ex-industrial or commercial property to residential. the term “loft” has come to represent a desirable type of dwelling space (open, bright, modern) and is associated with a wide spectrum of building types. lofts were originally popular amongst artists and bohemians because of their affordability and versatility. now that loft apartments have become a trendy style of living and so popular, loft living is anything but affordable. but as consumer demand for loftstyle homes continues to soar, there are also barriers to lofts development, which invariably concern cost. therefore the developers should perform complex analysis and versatile evaluation of ex-industrial building that can determine the success of investment project. the objective of the research presented in this paper is to develop an assessment model for non-residential property conversion options, which enables developers increase the effectiveness of investment projects. 2. methods in order to understand the general and local aspects of non-residential property conversion into apartments, the complex methodology of the research was formulated. the research includes: the analysis of literature in order to determine the stages of development and challenges of non-residential property conversion; the identification of potential alternative decisions of lofts conversion based to the theoretical assumptions and a study of the existing practice and the formulation of conversion projects development model, which enables real estate developers evaluate and select conversion option providing with increased effectiveness of investment. this is followed by the application of developed model to a real case study by consideration of various conversion options and implementation of multiple criteria evaluation methods. the developed assessment model for non-residential property conversion options is presented in fig. 1. the authors suggest the proper ex-industrial building conversion alternative can be selected by performing four essential analyses assessment of a building’s technical condition, determination of the technical feasibility of converting a building to a residential use, evaluation of project attraction for the consumers and multi-criteria assessment of building’s conversion alternatives. thus, first of all, the technical conditions of selected exindustrial buildings have to be assessed. the determination of the present technical condition of a building is subject to qualified technical investigation and historical inspection. a building inspection should be requested by developers in their own best interest prior to initiation of investment project. based on the results of the building inspection, the risk resulting from a loss or decrease in building functionality can be estimated. the risks can be expressed as costs associated with necessary repairs or reduction of building use as well as potential health hazards to the occupants and surrounding environment or even loss of life. it is possible to deduce forecasts of building technical development and model different strategies for repair, modernization, and conversion. the second step in evaluating the ex-industrial buildings conversion options is the research on their adaptability to the residential premises. to determine the technical feasibility of converting a building to an alternative use the following criteria are considered: size and height of building, building structure, building envelope and cladding, internal space, layout and access, building engineering systems, acoustic separation, fire safety and means of evacuation. all industrial buildings to be reconstructed into living premises should conform the complex of legal requirements for residential buildings, such as mechanical strength and stability, hygiene, health and environmental safety, noise insulation, energy saving and heat retention. one of the most important factors preventing conversion of industrial buildings into living space is their thermal insulation. as the thermal insulation of outdated industrial buildings is much worse than one required for residual use buildings. problems with any of the above-mentioned requirements fulfilment may impact on the implementation of conversion; this is the way changing of building’s use makes the designer’s job more difficult. at the same time large spaces and high ceiling of industrial buildings are a positive feature for lofts: it implies the application of various non-standard solutions. another important factor, which can impact the adaptability of ex-industrial property, is manufacturing process previously held in the building and its residual damage to human health. constructions of former industrial buildings and site soils, depending on the activities of the industrial object, may contain toxic, mutagenic or carcinogenic materials, which may eventually lead to health problems of residents of such premises (labutyte, 2012). therefore it is necessary to analyze the production processes, which took place in the building, their effects and possible residual harm for human health. it is obligatory to inquire about the history of the industrial building and to find out information about incidents and accidents that could have contaminated the premises. design and construction of loft apartments should correspond to all sanitation conditions that are obligatory for residential buildings without any threat for human health for the following reasons: excretion of harmful gases; hazardous particles and gases occurrence in the air; dangerous radiation; water and soil pollution and poisoning of living organisms; inappropriate disposal of wastewater, smoke, solid or liquid waste; moisture of 29 building constructions or internal moisture of buildings. if pollution norms are exceeded, neutralization of pollutants and its costs should be considered and the following analysis carried out: ▪ evaluation of the possibility of hazardous materials liquidation from the future housing site; ▪ economic impact of cleanup on the profitability of the project. prior to the development of conversion projects, all possible options must be analyzed. the other step in the assessment of adaptability of industrial building to the residential use is the analysis of the project attractiveness for the client. most of industrial buildings can be converted into the living space; however, not all of them are worth such conversion. the loft wave, which becomes more and more popular, together with the proponents of this lifestyle involves those people who are chasing fashion as well. fig. 1. complex model for assessment of ex-industrial building conversion options into lofts 30 according to the internet survey, conducted in marchapril of 2011 by lithuanian daily “lietuvos rytas”, more than a third of respondents (38 %) would eagerly purchase loft-type apartments because of their affordability. the uniqueness of the project was indicated as the second important reason (35 %) for the popularity of investing into former industrialized areas and lofts apartments. since lofts attract people due to their nonstandard and exceptional appearance, the places where they are located should also look exceptionally like, for example, water tower, clock tower on the upper floor of a factory or the upper floor of a skyscraper. therefore, the past activities in buildings are very important for conversion project’s liquidity in the context of attractiveness to the client in such a way that not so many people would like to live in former prison, psychiatric hospital or crematorium. moreover, the number of industrial buildings in the central or picturesque parts of the city is limited, and, in the course of time, they acquire a long-lasting value. the main problem faced by people living in lofts in lithuania is the real estate taxation applicable to commercial premises, which, under the laws of the republic of lithuania, is obligatory for all owners of commercial premises without consideration that commercial activities are not carried out any more. besides, changing the use of real estate property from industrial to residential is a lengthy and complicated process. therefore, consumers, purchasing a loft apartment with remaining industrial use, face limited opportunities to buy it. all the mentioned aspects must be considered in depth prior to decision on investing in conversion of any industrial building. hence, in the last step the authors recommend an assessment of different ex-industrial building’s conversion options in regard to the financial benefit for developers and cost-efficiency and functionality of the conversion itself. to determine the value and the utility degree of different ex-industrial building conversion alternatives under consideration and to establish the priority order of their implementation, multi-criteria decision-making methods (mcdm) can be used effectively. the authors suggest applying topsis method for selection of conversion alternatives for ex-industrial buildings, according to research of antucheviciene et al. (2011), who presented evaluation of different methods and measuring objective congruence (incongruence) of the obtained results and proved that the final decision should be adopted by giving the priority to the results of copras and topsis methods. a set of criteria was developed according to the economic and social aspects of non-residential property adaptation. the topsis method, like most of the mcdm methods, needs the criteria weights, which can be determined by pairwise comparison method ahp (analytic hierarchy process) or ranking expertise method. based on the judgments of experts, the weights of the criteria are determined, and the concordance of expert judgments is verified. once the alternatives for lofts conversion are selected, it can be implemented for the ex-industrial property conversion assessment regarding its economical feasibility. 3. results proposed non-residential property conversion model is applied to the case study to determine an adequate lofts conversion option providing efficient investment for developers. the case study is the complex of ex-industrial buildings “kauno pieno centras” located on the riverside in the inner city (fig. 2). the building of central dairy (total floor area 2622 m2) is selected for lofts conversion analysis (fig. 3). the first step in assessment of selected ex-industrial building is determination of the present technical condition according to the qualified technical investigation and historical inspection. the complex was built in 1936. since the start of kaunas dairy centre operation to its suspension in 2007 the main production activity carried out in the facilities was milk production, mainly the production of ice cream. fig. 2. complex of buildings “kauno pieno centras” (www.bing. com/maps/) fig. 3. central dairy building based on the results of the building inspection, the general physical depreciation of selected buildings complex can be defined according to the general wear and tear rates of separate building’s structures. although it was estimated that general physical depreciation rate of central dairy is 59,6 %, it is still suitable for the future development, repair, modernization or conversion. the second step in evaluating the ex-industrial building conversion options is determination of the technical feasibility of converting to the residential use. the following criteria were considered: 31 ▪ manufacturing process previously held in the building and its residual damage to human health – milk production processes, which took place previously in the dairy, do not belong to the hazardous activities; the building corresponds to all sanitation conditions that are obligatory for residential premises without any threat for human health. ▪ building structure, building envelope and cladding, building engineering systems – all structures of central dairy building conform main construction requirements for residential buildings, such as mechanical strength and stability, hygiene, health and environmental safety, noise insulation; at the same time building’s envelope, cladding and all engineering systems need to be renovated or rehabilitated. ▪ internal space and layout large spaces and high ceiling (6 m height) of the central dairy imply the application of various non-standard solutions: it can be split up into the separate apartments with installed entresols. ▪ other criteria – positive decision on the change of real estate property use from industrial to residential; advantageous location in the inner city of kaunas, on the riverside, etc. after the technical feasibility of converting is assessed, the social factors of conversion are evaluated. there are certain characteristics that are essential to loft living, which can attract or repel the potential clients: popular style of living, open space and versatility. in our case, the central dairy building can be represented as a perfect option for lofts apartments with high ceilings, large windows, exposed building materials and open concept living (fig. 4). another great aspect of analyzed option is the opportunity for eclectic design and decorating. besides, the floor plan can be altered at any time. fig. 4. internal space of central dairy located in the inner city of kaunas the building offers the location and opportunities of city life with far more space than average apartment and, possibly, a shorter commute to work. furthermore, manufacturing process previously held in the complex gives a positive image of building itself due to the sentimental feelings for living in former ice-cream factory. the case study investigates the selection of central dairy building conversion option that provides costefficiency and functionality of the conversion as well as financial benefit for its developers. based to the theoretical assumptions and a study of the existing practice three potential alternative decisions for central dairy conversion are suggested and implicated in the multiple criteria evaluation. the alternatives include hard loft (alternative a1), new hard loft (alternative a2) and soft loft (alternative a3). all the selected options are evaluated according to the general development project – to create 2467 m2 of living space in the central dairy building by constructing 23 loft apartments with utility premises in the basement and 50 parking spaces around the building. the a1 alternative – a hard loft is defined as a space transformed from an old, non-residential building like a warehouse, mill or factory to a residential dwelling (dolan, 2012). a true hard loft is characterized by high ceilings, open spaces, concrete ceilings and floors, exposed brick walls, duct work, electrical and plumbing, large windows and an urban location. the a2 alternative – a new hard loft is built to look and feel like hard lofts but offering advantages of modern building practices and materials (paterson, 2013). these lofts share the same characteristics of the true hard lofts (such as high ceilings, exposed brick and duct work, large windows etc.) but they are more habitable and comfortable than true hard lofts. new-builds embrace proper heating, electrical, plumbing and high efficiency windows and doors. essentially, new hard lofts have the best of both worlds. the a3 alternative – a soft loft approaches new hard loft in that it is newly constructed, but with some of the characteristics of a hard loft such as high ceilings, big windows and open concept floor plans (paterson, 2013). this type of lofts typically gain some of the subtleties instead of concrete floors they may have broadloom or hardwood; instead of exposed ductwork and piping these areas are encased in drywall; they may have upscale kitchens and baths. soft lofts have more in common with traditional apartments than a true hard loft. for the comparison of suggested alternatives a criteria system was developed and adapted for calculations that were performed to determine the priorities of loft conversion alternatives. the following criteria were taken into consideration including development project net present value (npv) c1, internal rate of return (irr) c2, profitability index (pi) c3, complexity of the development c4, duration of construction project c5 and the attractiveness of the project to market c6. initial data for multiple criteria decision-making was derived from the findings of the calculations on investment projects financial feasibility and in-depth analysis of selected loft conversion options as well as market demand in lithuania. criteria c1, c2 and c3, representing the investment efficiency, are calculated for the expected duration of conversion project from two to three years and project funding by equity financing (60 %) and bank loan (40 %) with discount rate of 5 %. the criteria c1, 32 c2, c3 and c6 are expected to reach their maximum values, while criteria c4 and c5 are targeted to minimum. the initial data for multiple criteria evaluation of loft conversion alternatives are presented in table 1. table 1. initial data criteria dimensions optimization direction alternatives a1 (hard loft) a2 (new hard loft) a3 (soft loft) c1 thousand ltl max 118 881 920 c2 % max 4 16 11 c3 max 1.04 1.17 1.14 c4 points min 4 7 8 c5 months min 6 12 15 c6 points max 5 8 4 the subjective weight of the attributes was determined by using expert pairwise evaluation as a subjective approach. pairwise evaluation of the criteria provided by experts is presented in table 2. table 2. subjective weights of criteria criteria total c1 c2 c3 c4 c5 c6 weight 0.193 0.183 0.213 0.113 0.133 0.163 1.00 multicriteria analysis of selected alternatives was performed applying topsis method. by applying this approach the efficiency of the alternatives of loft conversion has been determined and following priorities for the alternatives was obtained: a2, a3, a1. the calculation results are given in table 3. table 3. data obtained by applying topsis approach alternatives a1 (hard loft) a2 (new hard loft) a3 (soft loft) efficiency value, % 35 100 59 priority order 3 1 2 the findings of study suggest real estate developers that they can have the best financial benefit by converting central dairy building into new hard lofts. 4. conclusions currently, loft-type apartments have become a trendy style of living, reflecting social and financial status of the owner. loft conversions have grown in popularity for a number of social and environmental factors, including the growing interest in sustainability and energy efficiency. located in attractive locations, once-abandoned industrial buildings have become a marketable product for real estate developers. therefore, businessmen and real estate agents are eagerly investing in lofts. most of ex-industrial buildings can be converted into the living space; however, such conversion projects will only be interesting to developers if they are economically feasible. consequently, loft conversion developers should perform complex analysis and versatile evaluation of ex-industrial building that can determine the success of investment project. thus the complex model for assessment of non-residential property conversion into loft is presented in the paper. the developed model provides real estate developers with a needed support in defining the adaptability of exindustrial building for conversion as well as selecting appropriate loft conversion option in order to increase the effectiveness of investment project. the proper conversion alternative can be selected by performing four essential stages of analysis – assessment of building’s technical condition, determination of building’s technical feasibility for loft conversion, evaluation of project attractiveness for consumers and selection of the most efficient conversion alternative by implementation of multi-criteria decisionmaking methods. proposed model was applied to the case study – central dairy conversion into residential use investment project. three ex-industrial building conversion alternatives were suggested and implicated in the multiple criteria evaluation: hard loft, new hard loft and soft loft options. the findings revealed that the best option for the selected ex-industrial building transformation into living space, providing the best financial benefit of investment project, is new hard loft. references antucheviciene j., zakarevicius a. and zavadskas e. k. 2011. measuring congruence of ranking results applying particular mcdm methods. informatica, 22(3), 319–338. apklausa: už loftus kai kurie pasiryžę mokėti kaip už namus [survey: some people are ready to pay the house price for a loft]. 2011. available at: http://www.lrytas.lt/13069390381305626024-apklausa-u%c5%be-loftuskai-kurie-pasiry%c5%be%c4%99-mok%c4%97ti-kaipu%c5%be-namus.htm#.uubnavzbsy4 (accessed 15 january 2014) bullen p. a. 2007. adaptive reuse and sustainability of commercial buildings. facilities, 25 (1/2), 20–31. http://dx.doi.org/10.1108/02632770710716911 coutts j. 2012. loft conversions. west sussex, u.k.: john wiley & sons. dolan t. 2012. live-work planning and design: zero-commute housing. hoboken, n. j. : john wiley & sons. ellison l., sayce s. 2007. assessing sustainability in the existing commercial property stock. property management, 25 (3), 287–304. http://dx.doi.org/10.1108/02637470710753648 hamnett c. 2009. city centre gentrification: loft conversions in london’s city fringe. urban policy and research, 27 (3), 277–287. http://dx.doi.org/10.1080/08111140903132200 labutytė, i., 2012. gruntas, ant kurio gyvename: kaip jo užterštumas per ilgą laiką paveikia žmonių sveikatą [primer on which we live: how the pollution in the long term impacts on human health]. available at: http://www.technologijos. lt/p/spausdinti?name=s-24984 (accessed 15 january 2014) paterson j. 2013. hard lofts, soft lofts: what’s the difference? available at: http://www.realestateproarticles.com/art/6902/ 263/hard-lofts-soft-lofts-what-s-the-difference.html (accessed 15 january 2014) 33 remøy h. t., van der voordt t. j. m. 2007. a new life: conversion of vacant office buildings into housing. facilities, 25 (3/4), 88-103. http://dx.doi.org/10.1108/02632770710729683 remøy h. t., wilkinson s. j. 2012. office building conversion and sustainable adaptation: a comparative study. property management, 30 (3), 218–231. http://dx.doi.org/10.1108/02637471211233738 zukin s. 1982. loft living as ‘historic compromise’ in the urban core: the new york experience. international journal of urban and regional research, 6, 256–267. http://dx.doi.org/10.1111/j.1468-2427.1982.tb00577.x zukin s. 1989. loft living: culture and capital in urban change. new brunswick, n. j.: rutgers university press. received 2014 01 28 accepted after revision 2014 02 24 mindaugas daukšys – assoc. professor at kaunas university of technology, department of civil engineering technologies. main research area: real estate management, construction management, construction technologies. address: studentu st. 48, lt-51367, kaunas, lithuania. tel.: +370 37 300479 e-mail: mindaugas.dauksys@ktu.lt justas pilipavičius – msc., project manager in the joint stock company “lidl”. main research area: real estate development, real estate management. address: naugarduko str. 102, lt-03160, vilnius, lithuania. tel.: +370 693 00683 e-mail: justas.pilipavicius@gmail.com ala daugėlienė – phd, lecturer at kaunas university of technology, department of civil engineering technologies. main research area: real estate management, facility management, construction management and economics. address: studentu st. 48, lt-51367, kaunas, lithuania. tel.: +370 37 300487 e-mail: ala.daugeliene@ktu.lt 183 journal of sustainable architecture and civil engineering 2022/1/30 porous ceramics as sustainable material can become and, in some industries, already are used to achieve environmental applications considering their properties. research on important composition properties helps to identify the best product to be used in construction industry with a priority of a minimum number of raw materials and simplest and energy-efficient technology during production process. the elaborated research identifies compositions with glass waste, clay, and soot with minimum volume density within the range of chosen product line. water absorption, thermal conductivity, and compressive strength were researched to identify possible applications of elaborated material in construction industry. keywords: porous ceramics, glass, clay, waste materials. porous ceramics produced from glass and clay *corresponding author: aleksandrs.korjakins@rtu.lv porous ceramics produced from glass and clay received 2020/09/05 accepted after revision 2021/09/26 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 183-191 doi 10.5755/j01.sace.30.1.27604 jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.27604 pavels tihomirovs, aleksandrs korjakins riga technical university, department of building materials and products, institute of materials and structures, faculty of civil engineering, kalku street 1, riga abstract introduction today, improving energy and environmental performance is a key goal, of the construction industry and it is strategically important for achieving sustainability of construction materials. the development of new ecological insulation materials produced from municipal waste, ground glass waste, combustion waste, and raw materials is a topical problem in latvia. the effective properties of porous ceramics are depending on the microstructure as the result of fabrication technology. exploration of the relation between properties of material and microstructure can be used to quantify the influence of microstructure on properties of porous ceramic. one of the basic and important microstructural information is the pore volume fraction (porosity). a very important property of porous materials is their mechanical strength, which is mainly due to their composition and structure, preparation and treatment of raw materials as well as the technology of production. the second important property of porous materials is thermal conductivity. these two important properties are being evaluated in the research about porous ceramics. the utilization of waste glass in a porous material for construction industry is an important issue to be researched. “the versatility of the glass-ceramic production process is manifested by the many wastes that have been used as raw materials for glass-ceramics, which include coal fly ash…, mud from zinc hydrometallurgy …, slag from steel production …, ash and slag from waste incinerators …, red mud from alumina production …, waste glass from lamp and other glass products … as well as electric-arc furnace dust and foundry sands …. “. (rawlings, 2006). journal of sustainable architecture and civil engineering 2022/1/30 184 following raw materials glass waste, clay and a gasifier have been applied for obtaining porous ceramic, and sintering technology was the subject of this research. virtually all ceramic materials are constructed systems consisting of crystalline, glass, and gas phases (дятлова, 2012) in general, the temperature of the ceramic sintering process is between 800°c and 1200°c. fabrication temperature, which is used in the production of foam glass is in the range 790°c and 860°c (можегов, 2000), and in the range 700°c and 920°c (rautanen, 2020). the temperature of sintering depends on the gasifier used (dorokhova, 2017), (yakub, 2012). according to previously made researches the basic principle of porous material manufacture on a basis of glass waste using sintering methods of powder is to generate a gas in glass at the temperature between 700°c and 900°c (дятлова, 2012), (можегов, 2000), (rautanen, 2020), (dorokhova, 2017). the gas expands thus forming a structure of cells and producing a porous body. during the process of fabrication from green body to end product the material expands. the aim of the research is to elaborate the optimal composition of porous ceramics based on waste glass as raw materials with minimum number kind of raw materials with additives and low sintering temperature. materials compositions has been made according to previous researches and technologies elaborated by other researchers (dorokhova, 2017), (chen, 2021),. (капустинский, 2010), (погребенский, 2001), (апкарьян, 2009), (дамдинова, 2014), (rincon, 2018). following raw materials have been taken for preparing mixes for manufacturing porous ceramics: waste glass, clay, charcoal, sawdust, soot, and anthracite. part ingredient volume from the total raw material volume, % sio2 45.67 al2o3 12.27 fe2o3 5.34 tio2 0.67 cao 11.60 co2 11.22 k2o+na2o 4.56 part ingredient volume from the total raw material volume, % sio2 from 69 till 74% na2o from 10 till 16% cao from 5 till 14% mgo from 0 till 6% al2o3 from 0 till 3% other parts from 0 till 5% table 1 clay chemical composition table 2 glass chemical composition the ability of the clay to expand is very important in the porosity process. clays with good superficial properties contain illite, montmorillonite, iron oxide, aluminum oxide and calcium compounds, feldspar, dolomite, and quartz. clays are aluminosilicate materials with high sio2 (in our case 45.67%) and low al2o3 (12.27%) content, which participate in the formation of the ceramic partition. the low al2o3 content helps to reduce the softening temperature to 380°c and the resulting inflation temperature to 530°c. the high content of fe2o3 (5.34%) and cao 11.6% reduces the crystallization rate and temperature of sio2. sio2 and fe2o3 affect the viscosity, melt surface tension. the clays from the production plant of ltd. “ceplis” have been used as raw material in the mixes.. chemical composition of the clay is shown in table 1. chemical composition of used soot is c (94.84%), h (0.88%), s (0.01%), o (4.25%, other parts (0.02%). glass waste has been obtained from window glass. the chemical content of this one is shown in table 2. 185 journal of sustainable architecture and civil engineering 2022/1/30 sawdust obtained from the mixed hardwood and conifers was dried in an oven at 60° c for 48 hours before applying. glass waste was ground to a powder substance to a powder substance in planetary ball mill retsch pm400. glass was sieved through a 500 mkm sieve. based on the former researches three mixtures have been designed for investigation of the influence of different kinds of raw materials on the properties of porous ceramic. mixtures content by weight is shown in table 3. methods experiment nr. molten glass, % burning temperature, °c time of burning, minutes soot, % clay, % water, % x1 x2 x3 1 2 3 4 5 6 2.3.1. experiment 89.500 850 60 0.179 10.321 10.000 2.3.2. experiment 89.500 850 120 0.179 10.321 10.000 2.3.3. experiment 89.500 850 180 0.179 10.321 10.000 2.3.4. experiment 89.500 800 60 0.179 10.321 10.000 2.3.5. experiment 90.320 800 120 0.200 9.480 10.000 2.3.6. experiment 90.320 800 180 0.200 9.480 10.000 2.3.7. experiment 89.500 900 60 0.179 10.321 10.000 2.3.8. experiment 90.320 900 120 0.200 9.480 10.000 2.3.9. experiment 89.500 900 180 0.179 10.321 10.000 2.3.10. experiment 90.000 800 180 0.179 9.821 10.000 2.3.11. experiment 90.000 800 60 0.179 9.821 10.000 2.3.12. experiment 90.000 800 120 0.179 9.821 10.000 2.3.13. experiment 90.000 850 180 0.179 9.821 10.000 2.3.14. experiment 90.000 850 60 0.179 9.821 10.000 2.3.15. experiment 90.000 850 120 0.179 9.821 10.000 2.3.16. experiment 90.000 900 180 0.179 9.821 10.000 2.3.17. experiment 90.000 900 60 0.179 9.821 10.000 2.3.18. experiment 90.000 900 120 0.179 9.821 10.000 2.3.19. experiment 89.000 800 180 0.179 10.821 10.000 2.3.20. experiment 89.000 800 60 0.179 10.821 10.000 2.3.21. experiment 89.000 800 120 0.179 10.821 10.000 2.3.22. experiment 89.000 850 180 0.179 10.821 10.000 2.3.23. experiment 89.000 850 60 0.179 10.821 10.000 2.3.24. experiment 89.000 850 120 0.179 10.821 10.000 2.3.25. experiment 89.000 900 180 0.179 10.821 10.000 2.3.26. experiment 89.000 900 60 0.179 10.821 10.000 2.3.27. experiment 89.000 900 120 0.179 10.821 10.000 table 3 research compositions journal of sustainable architecture and civil engineering 2022/1/30 186 after weighing the raw materials were mixed by food mixer 1340 in dry conditions for 10 minutes. water was added continuously mixing during additional 10 minutes. the mix was molded in cube forms 50 * 50 * 50 mm and plate forms 300 * 300 * 30 mm , preparing samples for conductivity tests. molded compositions were left curing for 24 hours at room temperature. dried samples were fired in an oven for sintering. the operating temperature of each gasifier must be 50-70°c higher than the initial temperature of the melting glass powder. the softening temperature and the rate of increase of the partial pressure must be low. there were elaborated nine burning schemes (see fig. 1…fig. 9) fig. 1 burning scheme with maximum temperature 800°c during 60 minutes fig. 2 burning scheme with maximum temperature 800°c during 120 minutes fig. 1 burning scheme with maximum temperature 800°c during 60 minutes fig. 2 burning scheme with maximum temperature 800°c during 120 minutes fig. 3 burning scheme with maximum temperature 800°c during 180 minutes fig. 4 burning scheme with maximum temperature 850°c during 60 minutes fig. 5 burning scheme with maximum temperature 800°c during 120 minutes fig. 3 burning scheme with maximum temperature 800°c during 180 minutes fig. 4 burning scheme with maximum temperature 850°c during 60 minutes fig. 5 burning scheme with maximum temperature 800°c during 120 minutes fig. 3 burning scheme with maximum temperature 800°c during 180 minutes fig. 4 burning scheme with maximum temperature 850°c during 60 minutes fig. 5 burning scheme with maximum temperature 800°c during 120 minutes fig. 6 burning scheme with maximum temperature 850°c during 180 minutes fig. 7 burning scheme with maximum temperature 900°c during 60 minutes fig. 8 burning scheme with maximum temperature 900°c during 120 minutes fig. 6 burning scheme with maximum temperature 850°c during 180 minutes fig. 7 burning scheme with maximum temperature 900°c during 60 minutes fig. 8 burning scheme with maximum temperature 900°c during 120 minutes fig. 6 burning scheme with maximum temperature 850°c during 180 minutes fig. 7 burning scheme with maximum temperature 900°c during 60 minutes fig. 8 burning scheme with maximum temperature 900°c during 120 minutes three factor experiment was performed taking into estimation three parameters: x1ground glass % in the whole composition, x2burning temperature °c; x3 – time of burning in minutes. after weighing the raw materials were mixed by food mixer 1340 in dry conditions for 10 minutes. water was added continuously mixing during additional 10 minutes. the mix was molded in cube forms 50 * 50 * 50 mm and plate forms 300 * 300 * 30 mm , preparing samples for conductivity tests. molded compositions were left curing for 24 hours at room temperature. dried samples were fired in an oven for sintering. the operating temperature of each gasifier must be 50-70°c higher than the initial temperature of the melting glass powder. the softening temperature and the rate of increase of the partial pressure must be low. there were elaborated nine burning schemes (see fig. 1…fig. 9) fig. 1 burning scheme with maximum temperature 800°c during 60 minutes fig. 2 burning scheme with maximum temperature 800°c during 120 minutes fig. 3 burning scheme with maximum temperature 800°c during 180 minutes fig. 4 burning scheme with maximum temperature 850°c during 60 minutes fig. 5 burning scheme with maximum temperature 800°c during 120 minutes fig. 6 burning scheme with maximum temperature 850°c during 180 minutes fig. 7 burning scheme with maximum temperature 900°c during 60 minutes fig. 8 burning scheme with maximum temperature 900°c during 120 minutes 1 2 3 4 5 6 7 8 187 journal of sustainable architecture and civil engineering 2022/1/30 fig. 9 burning scheme with maximum temperature 900°c during 180 minutes after burning finishing and forms cooling, the samples were demolded and prepared for testing. the compression strength tests and thermal conductivity tests have been performed by universal testing system zwick 100 and fox600. density and water absorption have been measured in the framework of research. the porosity of the samples has been evaluated by microscope veho dx-3. two kinds of forms were used for burning the samples: metal for 50*50*50 mm samples (fig.10-11) and metal for 300*300*30 mm samples. fig. 9 burning scheme with maximum temperature 900°c during 180 minutes after burning finishing and forms cooling, the samples were demolded and prepared for testing. the compression strength tests and thermal conductivity tests have been performed by universal testing system zwick 100 and fox600. density and water absorption have been measured in the framework of research. the porosity of the samples has been evaluated by microscope veho dx-3. 9 fig. 10 metal form fig. 11 burning form made from metal10 11 two kinds of forms were used for burning the samples: metal for 50*50*50 mm samples (fig.1011) and metal for 300*300*30 mm samples. foil for 50*50*50 mm samples was used to let samples be taken out. forms contain holes to evenly heat the samples. some of the samples after burning can be seen in fig. 12-14. fig. 12 burning temperature 850°c 120 min fig. 13 burning temperature 850°c 120 min fig. 14 burning temperature 850°c 60 min fig. 15 sample under microscope (850°c 120 min.) (sample from the plate form) 12 13 14 15 journal of sustainable architecture and civil engineering 2022/1/30 188 results of water absorption tests of porous ceramic samples are shown in table 4. table 4 water absorption test results experiment sample nr. weight after sintering, g volume density, kg/m3 weight after 6 days, g water absorption, % 3-1 46.00 494.19 77.80 69.13% 3-1-1 31.10 259.60 89.60 188.10% 3-2 32.40 345.97 62.50 92.90% 3-2-1 46.90 358.20 85.80 82.94% 3-3 40.20 378.75 68.80 71.14% 3-3-1 33.30 376.70 59.50 78.68% 3-4 47.60 364.94 77.20 62.18% 3-4-1 37.00 341.44 70.10 89.46% the increase of samples volume and volume density of the ceramic samples were measured. prepared samples were tested for compressive strength. the results of the experiment are shown in table 5. results table 5 experiment results experiment nr. volume increase after sintering, times compressive strength, mpa volume density, kg/m3 2.3.1. experiment 4.69 1.06 306.00 2.3.2. experiment 4.18 0.45 232.13 2.3.3. experiment 4.68 1.19 329.53 2.3.4. experiment 5.04 0.69 299.70 2.3.5. experiment 4.66 1.31 318.86 2.3.6. experiment 4.26 1.38 296.47 2.3.7. experiment 4.73 0.81 317.94 2.3.8. experiment 4.37 0.70 291.70 2.3.9. experiment 4.32 0.80 271.67 2.3.10. experiment 4.68 1.40 326.59 2.3.11. experiment 4.54 1.25 311.64 2.3.12. experiment 5.05 1.31 295.37 2.3.13. experiment 4.17 0.81 274.37 2.3.14. experiment 4.91 0.84 271.36 2.3.15. experiment 4.42 1.19 264.64 2.3.16. experiment 4.31 1.31 322.08 2.3.17. experiment 5.18 0.74 328.04 2.3.18. experiment 4.84 0.51 285.39 2.3.19. experiment n/a 1.35 291.85 189 journal of sustainable architecture and civil engineering 2022/1/30 volume density of the obtained samples is in the range from 232.13 to 329.64 kg/m3 (table 5) with minimal value for experiment nr. 2.3.2. volume density of the obtained ceramic depends on content of the raw materials– more volume of clay increases the density in the final product. the density depends on the sintering temperature as well. the compressive strength of the obtained samples is in the range from 0.45 mpa to 1.41 mpa depending on the burning temperature and composition (see table 5). the obtained thermal conductivity for samples from experiment nr. 2.3.2. is 0.088 w/(m k) with a sample thickness 51 mm. volume of expanded samples increase from 3,68 till 5,18 times from the initial volume. measured water absorption of the porous ceramic samples is in the range from 62.18% till 188,10%, which may be evaluated as high. sizes of the pores are in the range 0.12 -3.40 mm (see fig. 15). by analysis of obtained experimental results of elaborated compositions by software statistica the optimal parameters of porous ceramics, such as volume density of 249 kg/m3 can be achieved by temperature 852°c with a sintering period of maximum temperature 124 minutes. discussion during previous researches according to made experiments, it was found that the range of the melting temperatures is from 850°c to 1200°c depending on the composition of the raw materials. after the specified temperature limit, the solid phase increases, and the gas phase in the material decreases, as a result of which the sample becomes dense and ineffective as insulation porous ceramic material. the process of forming the ceramic structure is created in the following stages of coagulation-> sintering -> pore formation. the coagulation structure is formed by the action of intermolecular forces between the clay particles at the interlayers of the liquid medium, forcing the filler from the substance onto the surface layer during granulation. during drying, a condensation structure forms after the removal of the liquid phase. as a result of heating, the amorphous structure is formed by burning the glass-ceramics with intermediate pores forming a solid uniform system. in the general case, as the volume density increases, the compressive strength also increases. the density and size of the pores depend on the sintering temperature and the amount of the gasifier. as the sintering temperature increases, the volume density decreases, the number of pores increases, and the mechanical strength decrease. the strength of a ceramic product is affected by various modified additives that are used to form the structure of the ceramic product. the duration of foaming also affects the pore structure and accordingly also to the compressive strength. at the longer foaming time, the gas pressure in the pores increases, in result the pore’s size increases and makes the pore partitions more fragile, which leads to a decrease in compressive strength. experiment nr. volume increase after sintering, times compressive strength, mpa volume density, kg/m3 2.3.20. experiment 5.13 1.20 310.13 2.3.21. experiment 3.99 1.22 320.78 2.3.22. experiment 4.45 0.73 285.24 2.3.23. experiment 4.06 1.41 310.62 2.3.24. experiment 4.26 0.72 255.24 2.3.25. experiment 4.09 0.90 310.17 2.3.26. experiment 4.90 1.11 326.71 2.3.27. experiment 3.68 1.31 329.64 journal of sustainable architecture and civil engineering 2022/1/30 190 achieved thermal conductivity of 0.088 w/(m k), which is similar to the performance of porous construction products in this group of construction materials. water absorption depends on the shape of the pores, the amount of opened pores and sizes of the pores. the shape and size of the pores depend on the composition, amount of gasifier, temperature, and time of burning. to achieve the lowest water absorption results, it is necessary to elaborate compositions with a larger number of closed pores. references chen y., wang n., ola o., xia y., zhu y. porous ceramics: light in weight but heavy in energy and environment technologies. mater. sci. eng. r reports, vol. 143, p. 65, jan. 2021, https://doi.org/10.1016/j. mser.2020.100589 dorokhova e. s., zhernovaya n. f., bessmertnyi v. s., zhernovoi f. e., tarasova e. e. control of the structure of porous glass-ceramic material. glas. ceram., vol. 74, no. 3, pp. 95-98, 2017, https://doi. org/10.1007/s10717-017-9936-x luckham p. f., rossi s. colloidal and rheological properties of bentonite suspensions. adv. colloid interface sci., vol. 82, no. 1, pp. 43-92, 1999, https:// doi.org/10.1016/s0001-8686(99)00005-6 monich p. r., romero a. r., höllen d., bernardo e. porous glass-ceramics from alkali activation and sinter-crystallization of mixtures of waste glass and residues from plasma processing of municipal solid waste. j. clean. prod., vol. 188, pp. 871-878, jul. 2018, https://doi.org/10.1016/j.jclepro.2018.03.167 rautanen j., jääskeläinen t. process for producing foam glass. ep 3 656 747 a1, 2020. rawlings r. d., wu j. p., boccaccini a. r. glass-ceramics: their production from wastes. a review. springer science and business media llc, 2006; [online]. available: https://core.ac.uk/download/pdf/294576.pdf. rincón a., desideri d., bernardo e. functional glass-ceramic foams from ‚inorganic gel casting‘ and sintering of glass/slag mixtures. j. clean. prod., vol. 187, pp. 250-256, 2018, https://doi. org/10.1016/j.jclepro.2018.03.065 yakub i., du j., soboyejo w. o. mechanical properties, modeling and design of porous clay ceramics. mater. sci. eng., vol. a 558, pp. 21-29, 2012. https:// doi.org/10.1016/j.msea.2012.07.038 апкарьян а.с., абакумов е. п., христюков в. г. способ изготовления пеностеклокерамики [method of making foam glass ceramics]. рф 2374191, 2009. дамдинова д. р., анчилоев н. н., павлов в. е. пеностекла системы стеклобой глина гидроксид натрия:составы, структура и свойства. строительные материалы, no. 8, 2014, accessed: may 05, 2021. [online]. available: https://cyberleninka.ru/article/n/penostekla-sistemy-stekloboy-glina-gidroksid-natriya-sostavy-struktura-i-svoystva. дятлова е. м. химическая технология керамики и огнеупоров [chemical technology of ceramics and refractories]. 2012. капустинский н. н., кетов п. а,. кетов ю. а. способ получения пеностеклянных изделий [method of obtaining foam glass products]. ru 2453510, 2010. можегов в. с., ли чи-тай, суворов с.а., шевчик а.п., способ получения пеностекла [method of obtaining foam glass]. ru2187473c2, 2000. погребенский г. м., искоренко г.и., канев в.п. способ изготовления гранулированного пеностекла из стеклобоя [method of manufacturing granulated foam glass from cullet]. рф 2162825, 2001. conclusions it was obtained experimentally that the sintering temperature of a porous ceramic material can be reduced to 800-850°c by creating a ceramic composition with a glass content of 89% -90% and using soot as a gas generating agent in amount 0.179-0.200%. by analysing water absorption results (from 62.33% to 188.10%) it can be concluded that all the tested samples have a large number of open pores, therefore the water absorption is high. the obtained thermal conductivity result is 0.088 w/(m k) for composition 850°c during 120 minutes indicates that the obtained tested samples are close to diatomite thermal insulation materials (0.115 0.162 w/(m k)). the obtained increase in volume during the sintering process in comparison to the initial volume is from 3 to 5 times, which corresponds to other researches (rautanen, 2020). 191 journal of sustainable architecture and civil engineering 2022/1/30 pavels tihomirovs position at the organization phd student main research area building materials, porous ceramics, recycling of glass. address riga technical university, department of building materials and products kalku street 1, riga lv1658 tel. +371 67089248 e-mail: mans.pasts@gmail.com about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). aleksandrs korjakins position at the organization professor, head of department of building materials and products main research area building materials, porous ceramics, uhpc and light concrete, recycling, insulation materials, ecological materials applying waste from agricultural industry. address riga technical university, department of building materials and products kalku street 1, riga lv1658 tel. +371 67089248, +371 26422442 e-mail: aleksandrs.korjakins@rtu.lv 42 darnioji architektūra ir statyba 2014. no. 1(6) journal of sustainable architecture and civil engineering issn 2029–9990 recycling of glass wastes in latvia – its application as cement substitute in self-compacting concrete patricija kara* riga technical university, institute of materials and structures, department of building materials and products, 1 kalku str., riga, lv-1658, latvia. *corresponding author: patricija.kara@rtu.lv http://dx.doi.org/10.5755/j01.sace.6.1.6127 the rate of treated waste glass within the last 10 years has risen up to 25 % due to improved waste glass collecting system in latvia, however the glass waste recycling infrastructure is still up to date issue due to absence of local recycling companies. application of glass wastes as cement substitute has significant effect on the properties of concrete making it eco-friendly construction material with several benefits like: decrease of accumulated glass wastes in landfills, the reduction of non-renewable natural resource consumption, the reduction of cement content up to 20–30 % and the reduction of greenhouse gas emission. in the present investigation was evaluated the effectiveness of ground soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp waste chips, borosilicate glass coming from incandescent light bulb waste chips, soda-lime glass cullet coming from beverage containers on workability, compressive strength and frost resistance of self-compacting concrete. keywords: glass wastes, scc. 1. introduction recycling of glass wastes in latvia approximately 50,000 tonnes of glass packaging waste is generated annually in latvia (see table 1). there are no recycling facilities for glass in latvia (ec.europa.lv), most of the glass waste is landfilled or exported by several companies dealing with preparation of glass for re-use to the neighbor countries. the opportunities for the recovery and recycling of different packaging waste vary between the countries. in latvia, there is the only one lamp recycling centre in the baltic states located in liepaja, which in 2012 recycled 159 tonnes of lamp glass waste (see fig. 1). fig. 1. incandense lamp and fluorescent tubes recycling statistics (www.meteo.lv) in estonia, glass packaging factory exists (jarvakandi klaas), but it requires a very good quality (the quality from the glass collected through the deposit system is good, but the quality from the glass collected through the containers is mostly not good enough (mixed glass)) and does not accept the green glass. some of the glass is used to produce street pavements, stones etc, the rest is still exported. several other recycling projects are in a certain stage, getting 50 % support from the eu cohesion program. but they are still unable to proceed, as there is no clarity around the waste sector is still too big for the financial institutions to provide rest of the financing (ec.europa.ee). there are four glass recycling companies in lithuania (cjsc “kauno stiklas”, jsc “warta glass panevėžys”, cjsc “alytaus keramika”, cjsc “stikloporas”) which have quite a high glass recycling capacity (54.7 kt/a) (ec.europa.lt), thus, this waste is even imported. in conjunction with economic growth and increased consumption, packaging amounts (defined as all products made of any materials of any nature to be used for the containment, protection, handling, delivery and presentation of goods that, when discarded) ending up in waste streams during all this time were increasing. packaging waste was generated along with municipal waste (household and commercial waste). due to a lack of a separate collection system, packaging waste has mainly been disposed of at 43 landfills. although certain steps to promote recovery and recycling have been taken, comprehensive reporting on the whole packaging waste management chain has not been performed. the total amount of separately collected packaging waste was less than 5 % of the total municipal waste stream in 2002. and that indicated a weakness in the existing reporting/collection system. when, for example, estonia introduced an excise tax on beverage packaging in 1997, with the goal of increasing recovery and recycling, due to high tax rate, almost all of the companies fulfilled packaging waste recovery targets. in 2003 a new instrument – a deposit system for glass bottles to increase reuse of refillable glass packaging was introduced in latvia. the packaging waste management system in latvia became based on the “producer responsibility” principle producers and importers are required to organise the packaging waste management system. there were recently founded packaging management organisations whose aim is to improve the situation by establishing separate collection systems also promoting the collection and primary sorting of packaging waste due to that mostly depends on the goodwill and awareness of the public, as so called habit of each citizen to sort wastes at the first place. in 2013 waste sorting (mainly waste glass and plastics) has become more popular in latvia than it was in the previous years. this is evidenced by presence of special waste separation containers and drop-off points for wastes in latvia. however, there is still absence of factories that could recycle glass wastes and latvian recycling infrastructure is based mostly on limited operations like: waste glass collection, sorting and export to eu. as there is absence of data in statistics, as it can be seen from table 1, there is no complete statistics on waste glass collected and recycled amount in latvia, according to the regulations the total amount which should be recycled yearly is 50 %, and that is shown but other items are not reflected in the last year reports. according to eurostat statisticdata available, the amount of collected waste glass (container) from 2008 to 2011 year increased approximately 2 times. this can be explained by the fact that latvian population became more interested in the clean environment, more information about sorting and recycling were delivered to the public. also eurostat statistics shows progress for 2010 in latvia, the amount of collected glass was 8848 t and the amount of treated glass waste was 2800 t and that is 30 %, which is better result than in 2002. in 2012 were collected around 9200 t of waste glass (container glass and other separately collected glass), 22 t were treated and 49 t were disposed in landfills. the rest of waste glass was, probably, exported to other countries: lithuania, belorussia, ukraine and poland. however, amount of collected waste container glass decreased in 2012, while the total amount of collected waste glass increased. application of waste glass powder as cement substitute in self-compacting concrete rapid depletion of resources and concerns over degradation of the environment has led to a growing emphasis on sustainable development (meyer, 2002). as a result, the construction industry is required to adopt environmentally friendly practices and make judicious use of natural resources. the most important political development over recent years has been the increasing commitment by industrialised countries to reduce co2 emissions (damtoft et al., 1999). portland cement production is third largest contributor of co2 emissions after the energy and transportations sectors (hansen et al., 2007). for every tonne of portland cement produced, cement plants generate approximately one tonne of carbon dioxide (davidovits, 1993). the concrete industry can address growing environmental and energy concerns by minimizing the cement content in concrete required to meet the required performance levels; this goal can be accomplished by replacing as much of portland cement as possible with pozzolanic supplementary cementitious materials (scms) (meyer, 2009). recycling of glass waste by converting it to aggregate not only saves landfill space but also reduces the demand for extraction of natural raw material for construction activity (rakshvir and barai, 2006). if 30 % of portland cement is replaced with waste glass in good structural table 1. packaging waste recycling statistics in latvia within 2003–2011 years (statistical reports 2005–2013) year l at vi an p ur ch as ed gl as s pa ck ag in g w as te (t ) t he im po rt ed gl as s pa ck ag in g w as te (t ) e xp or te d gl as s pa ck ag in g w it h go od s (t ) g en er at ed g la ss pa ck ag in g w as te (t ) r eu se d gl as s pa ck ag in g w as te (t ) t he c ol le ct ed g la ss pa ck ag in g w as te (t ) g la ss p ac ka gi ng w as te e xp or te d fo r re cy cl in g (t ) g la ss p ac ka gi ng w as te r ec yc le d in l at vi a (t ) t he to ta l v ol um e of r ec yc le d gl as s pa ck ag in g (% ) r ec la im ed g la ss pa ck ag in g w as te (t ) r ec la im ed g la ss pa ck ag in g vo lu m e (% ) 2003 32585 45034 15826 62193 29010 15829 3333 12523 26 15856 26 2004 44416 55817 18307 73771 27201 24014 7474 14503 30 11851 16 2005 260 4 110 58565 ------5786 21558 47 ------2006 9682 19445 16609 63639 5173 ---10970 23998 55 ------2007 9202 30592 4555 78973 87 ---13122 22917 46 10 ---2008 ----* ------66788 ------15324 35424 ---------2009 ---------44323 ------6692 19690 ---------2010 ---------51896 ------7648 24704 ---------2011 ---------51967 ------7731 26814 ---------* --- data is not reflected in the reports 44 concrete made with 320 kg/m3 of portland cement then co2 emissions into atmosphere will be reduced from 0.41 to 0.29 tonnes of green house gas emissions. a number of research studies have been performed within the last years. park et al. (2004) reported that the compressive, tensile, and flexural strengths of concrete containing waste glass as fine aggregate demonstrated a decreasing tendency with increase in the mixing ratio of the waste glass. dyer (2001) reported that cullet from container glass clearly undergoes a pozzolanic reaction when combined with portland cement up to 30 % replacement in concrete without any long term detrimental effects. the influence of supplementary cementitious materials like fly ash and waste glass has impact on workability and can significantly improve rheological properties. the effects of particle size on reactivity of pozzolanic scms and glass has been demonstrated (day, 1994; shi, 2001), where increased fineness led to an increase in early age compressive strength, even in the absence of activators. in some cases, the compressive strength of specimens made with glass powder as an scm demonstrated a higher compressive strength than those made with an equivalent amount of fly ash (shao et. al., 2000; schwarz, 2008). concrete durability to a large extent depends on its mechanical strength, which in turn depends on the concrete mixture proportions as well on the placing conditions. in fact, concrete mechanical strength increases by decreasing the mixing water for a given cement amount, but the less the water is in the concrete mixture, the more the concrete placing is difficult due to its workability loss. self-compacting concrete with a certain amount of very fine glass particles as a filler, together with a viscosity modifying agent able to keep fresh concrete viscous enough to avoid bleeding and segregation (corinaldesi and moriconi, 2005). one of the commonly used filler to increase packing density is condensed silica fume which is a relatively high cost material. in the recent years waste glass powder ground to particle size less than 100 µm (no alkali-silica reaction had been detected with particle sizes up to 100 µm (corinaldesi et al., 2005)) in a dry environment or in a wet environment to receive finer particle size (kara, 2013) becomes quite popular material to substitute cement and aggregates. wood ash used as a partial replacement for ordinary portland cement at replacement levels up to 10 % by total binder weight can produce structural grade concrete or mortar with acceptable strength properties (ban and ramli, 2011). a major portion (approximately 70 %) of the wood waste ash produced is landfilled as a common method of disposal. as wood waste ash consists of highly fine particulate matters, which can be easily rendered airborne by winds, such a means of waste disposal may result in subsequent problems, namely, respiratory health problems to residents dwelling near the disposal site of the ash material. hence, disposal of wood waste ash by means of landfilling require a properly engineered landfill which have implications in terms of the cost of disposal. 2. materials and methods a commercial portland cement cem i 42.5n (bogue calculation from xrd c3s – 5.4, c2s – 19.3, c3s – 51.7, c4af – 9.9, gypsum – 5.0) was used. portland cement compressive strength at the age of 28 days was 55 mpa, initial setting time 102 min, final setting time 202 min. fig. 2. container glass recycling process in laboratory conditions portland cement was substituted at 2 levels – 20 % and 30 % with waste glass powder or bottom ash per mass of portland cement. soda-alkaline earth-silicate glass (named as lb) coming from low pressure mercury-discharge lamp waste chips, borosilicate glass (named as drl) coming from incandescent light bulb waste chips, soda-lime glass cullet (named as a – amber colour glass bottles, g – green colour glass bottles, f – flint colour glass bottles) coming from beverage containers crashed manually under laboratory conditions were used for production of waste glass powder (see fig. 2). fig. 3. grading curves of waste glass powders, bottom ashes and portland cement used in the study waste glass chips were washed, dried and ground for 30 minutes into powder in laboratory planetary ball mill retsch pm400 (with rotation speed 300 min-1). sika viscocrete d 132-2 plasticizing agent was employed for preparing concrete mixes at a dosage of 1.8 % by weight of cement. local gravel and sand from natural sources were used in the experimental work. the used gravel had 45 a nominal maximum size of 11.2 mm. the used sand had a nominal size of 1mm and 2,5mm. bottom coal ash (named as ca) and wood ash (named as wa) were obtained from local sources in latvia. the chemical composition and fineness of waste glass and bottom ashes measured in conformance with en 196-6 (blaine method) are given in table 2. particle size distribution of waste glass powders, ashes and portland cement is shown in figure 3. fifteen different scc concrete mixtures were produced: one reference mixture, 10 mixtures with 20 % and 30 % portland cement substitution with waste glass (drl/lb/amber/green or flint) and 4 mixtures with 20 % and 30 % portland cement substitution with bottom ash (coal or wood) (see table 4). all mixtures were essentially self-compacting concrete and the mixture composition was constant for all mixtures, w/c = 0.4 was applied for reference mixture and water/binder = 0.4 was applied for mixtures with portland cement substitution with waste glass powder or ashes. reference mixture composition (kg/m3): cement – 450, silica fume – 80, sand 0.3/2.5mm – 600, sand 0/1mm – 360, gravel 4/11.2mm – 700, water – 180, plasticizer – 8. the mixing of concrete batches was performed in the spiral vortex concrete mixer for 3 minutes (see fig. 4). tests were conducted on fresh concrete to determine the slump flow (bs en 12350-8:2010), l box ratio (lvs en 12350-10:2010) and v – funnel values (bs en 123509). for each concrete mixture, three 100∙100∙100 mm concrete specimens were cast into the steel moulds for the determination of compressive strength. after casting all concrete specimens were covered with polyethylene wrap. after 36 hours specimens were removed from the moulds and cured in water tank for 28 days in a curing chamber (at temperature +20±2°c and relative humidity ≥95 %) until the tests were carried out. compressive strength of concrete specimens was determined at the age of 7, 28 and 90 days according to lvs en 12390-3:2009. the frost resistance tests were carried out in accordance with гост 10060.0-95, гост 10060.1-95, гост 10060.295 and гост 26134-84. accelerated frost test method was used and strength losses in the specimens were measured recording the ultrasonic velocity changes; further details of the specimen preparation and method description are available in (kara, 2013). concrete specimens which were subjected to frost tests had prismatic shape with internal dimensions of 60∙60∙180 mm. three specimens per each mixture were prepared. all specimens were marked with measuring points – 4 points forming two diagonals on two opposite long sides of the specimens and 1 centre point on each short side in order to record the ultrasonic velocity in the same places. one diagonal length is 15 cm, which is a tuner base at the same time (distance between the contact elements) for portable tester “uk-1401” (see fig. 5). for the most accurate results, the ultrasonic velocity of each diagonal was measured 3 times. the concrete specimens were saturated in 5 % saltwater at a temperature of 18 ± 2 °c for 3 days, on 4th day ultrasonic pulse velocity and weight measurements were performed before freeze-thaw cycling. specimens freezing procedure was carried out in accordance with гост 10060.1-95 in the climatic chamber ilka ktk800 (veb maschinenfabrik nema netzschkau, 1988) at a temperature –18 ± 2 °c and thawing in 5 % salt-water at a temperature of 18 ± 2 °c. decrease of ultrasonic velocity and mass of the specimens were recorded after 8th, 13th, 20th, 30th and 45th cycle. if the decrease of ultrasonic velocity didn’t exceed 5 % and decrease of weight didn’t exceed 3 %, it is considered that the specimen has passed number of cycles and frost resistance tests were continued. fig. 4. concrete batch mixing in the spiral vortex concrete mixer table 2. the chemical composition and fineness of glass waste powders, ashes and portland cement name bulk oxide, mass (%) fineness m2/kgsio2 al2o3 fe2o3 cao na2o k2o mno mgo tio2 so3 p2o5 portland cement 20.31 4.13 3.26 60.64 0.51 1.07 0.05 2.06 0.34 2.95 0.12 389 drl glass powder 71.14 2.60 0.17 1.320 3.30 1.70 0.006 0.62 0.006 0 0.023 608 lb glass powder 65.52 1.22 0.11 5.11 12.35 1.88 0.01 2.95 0.027 0.14 0.038 542 flint glass powder 69.61 1.34 0.08 11.30 11.21 0.56 0.008 0.46 0.028 0.13 0.021 502 green glass powder 67.8 1.53 0.36 10.93 11.09 0.55 0.018 1.58 0.06 0.04 0.02 463 amber glass powder 69.26 1.42 0.36 10.93 11.43 0.55 0.02 3.08 0.06 0.04 0.02 542 wood ash 40.69 14.1 8.29 13.5 0.43 1.34 0.178 3.49 0.631 0.55 0.745 660 coal ash 59.93 3.59 1.91 20.42 1.27 5.36 0.47 3.5 0.193 0.02 1.72 849 46 fig. 5. prismatic shape concrete specimens for frost resistance test 3. results and discussion in order to have better overview of the effect on concrete mixture workability of application of different waste glass powders and ashes as portland cement substitutes vicat needle penetration measurements were carried out on cement pastes containing waste glass powders and ashes according to bs en 196-3 and performed on zwick/roell toniset automatic vicat needle instrument. the results are shown in table 3 and indicate that waste glass powders and ashes have a retarding effect on setting. it can be seen that the substitution of portland cement at levels from 20 % to 30 % with waste glass can significantly increase the workability of concrete, especially for concrete mixtures with 30 % portland cement substitution. this attributed to the weaker cohesion between the glass aggregates and the cement paste due to their smooth surfaces. in the case of the paste containing f glass (20 %), the initial setting time was delayed by 11 minutes relative to the reference ctrl paste. in the case of the paste containing lb glass (20 %), the initial setting time was delayed by 31 minutes relative to the reference ctrl paste. f glass performed worse workability and lb glass performed the best workability in comparison to other four glasses. it was observed that concrete mixture with drl waste glass powder is always more viscous than concrete mixture with lb waste glass powder. initial setting time of lb cement paste was delayed for 14 minutes in comparison to drl cement paste. in the case of the paste containing bottom ashes, the initial setting times were delayed up to 51 minutes when the level of substituted cement was lower and was 20 %. it could be described by high water absorption of bottom ashes in concrete mixture, especially of coal bottom ashes. all concrete mixtures had slump flow over 600 mm (see table 4) and did not exhibit segregation except mixture 7 where w/c could be lower. l-box ratios (see table 4) varied from 0.83 to 0.90, the results indicates that scc mixtures with waste glass powder prepared in this study achieved adequate passing ability and maintained sufficient resistance to segregation. the v-funnel test time was 3.5– 6 s, the best time for lb glass and worse time for drl glass concrete mixture. table 3. setting time of cement paste mortars with portland cement substitution with waste glass powders and ashes cement paste mortar’s type substitution level, % setting time initial time, h final time, h ctrl 0 1:42 3:22 drl 20 1:59 3:54 drl 30 2:20 3:15 lb 20 2:13 3:26 lb 30 2:28 3:56 f 20 1:53 3:45 f 30 2:14 3:07 a 20 2:10 4:11 a 30 2:23 3:43 g 20 2:09 3:13 g 30 2:17 3:33 wa 20 2:33 3:21 wa 30 2:04 3:05 ca 20 2:07 3:02 ca 30 1:40 4:49 the tests results for compressive strength are summarized in table 4. each given value is the average of three measurements. it can be seen that the use of recycled glass waste and bottom ash as a portland cement replacement decreases the compressive strength of the scc mixtures compared with the reference mixture, except for mixtures with drl glass for all ages and amber glass at the age of 28 and 90 days. park et al. (2004) found that addition of 30 % of waste glass to concrete caused a decrease of 4 % in compressive strength, compared with its reference mixtures. in the present investigation the decrease of compressive strength at the age of 28 days was up to 8 % for concrete mixture with waste glass powder (30 %). the equal compressive strength of concrete mixture with drl waste glass powder (20 %) to reference mixture could be attributed to the effect of pozzolanic reactions and the high degrees of strength enhancement were obtained when the pozzolanic effect became significant at the late age of 90 days. as it can be seen that a smaller particle size of the ground glass resulted in a higher activity of glass with lime, however the workability of concrete mixture with drl waste glass powder was lower, compressive strength was higher in comparison to other concrete mixtures in this investigation. the bottom ash concrete mixtures performed lower compressive strength results in comparison to waste glass concrete mixtures. however, as it can be seen coal bottom ash always perform better compressive strength results and worse workability, when wood bottom ash perform better workability which is quite important for scc concrete mixtures, in turn the compressive strength for mixtures with wood bottom ash might be raised by addition of several chemical admixtures. mineral admixtures in frost-resistant concrete especially with the large water requirements are undesirable. at the same time, it can be seen that concrete with non47 large maintenance of waste glass powders (in case of scc concrete mixtures) may be satisfactory for frost resistance. table 5. decrease of ultrasonic pulse velocity, % concrete mixture number of freeze-thaw cycles for the frost resistance class determination f50 f75 f100 f150 f200 8 13 20 30 45 ctrl -0.5 0 -1.8 -3.7 -4.9 2 -0.9 -2.17 -3.5 -5.0 3 -1.75 -3.56 -4.89 4 -1.95 -3.87 -5.0 5 -4.5 6 0 -2 -4.9 7 -4.9 8 -2.0 -2.0 -5.0 9 -4.9 10 -1 0 -4.8 11 -4.9 12 -1.0 -2.0 -5.0 13 -4.7 14 -1.0 -2.0 -4.9 15 -4.5 the results (see table 5) show that all mixtures belong to 1st or 2nd class: 1st class – non-large frost resistance (f = 50 to 150) and 2nd class – large frost resistance (f = 150 to 300). the experiments showed that addition of waste glass powder decrease the frost resistance however by proper mixture composition selection and application of waste glass powder the frost resistance can be significantly improved. 4. conclusions in the present investigation designed scc concrete mixtures with waste glass powders as portland cement substitute demonstrated reasonable improvement on workability, compressive strength and frost resistance. the slump flow, flow ratio, and v-funnel of recycled glass scc mixtures increased with the increase of recycled glass powder content. the best results for concrete workability were performed with soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp waste chips as cement component in concrete. the flow ratios varied from 0.83 to 0.90. the compressive strength of recycled glass powder scc mixtures decreased with the increase of recycled glass powder content (addition of 10 % of waste glass powder by weight approximately decreases compressive strength for 10 mpa). the difference in results for different waste glass powders could be explained by its chemical composition and fineness, when fineness sometimes even more important for scc concretes. addition of waste glass powder in concrete performed satisfied results and can be considered as one of the option to reduce accumulated waste in latvia, where glass recycling problems are still upto-date. references ban, c. c., ramli, m. 2011. the implementation of wood waste ash as a partial cement replacement material in the production of structural grade concrete and mortar: an overview. resources, conservation and recycling 55, 669–685. http://dx.doi.org/10.1016/j.resconrec.2011.02.002 bs en 12350-8:2010 testing fresh concrete. self-compacting concrete. slump-flow test bs en 12350-9 testing fresh concrete. self-compacting concrete. v-funnel test bs en 196-3 2005+a1:2008 methods of testing cement. determination of setting times and soundness. corinaldesi v., moriconi g. 2005. reological study of blended cement concrete, cement combinations for durable concrete, thomas thelford, 211–218. table 4. fresh and hardened properties of scc mixtures with waste glass powder and bottom ash as a portland cement component in concrete mixture name of substitute of portland cement portland cement, kg/m3 substitute of portland cement, kg/m3 slump flow diameter, mm v-funnel test l-box ratio compressive strength, mpa frost resistance class7d 28d 90d ctrl 450 0 620 5 0.87 52 73 87 f200 2 drl 360 90 620 6 0.84 51 74 88 f150 3 drl 315 135 635 5 0.86 49 71 82 f100 4 lb 360 90 635 4 0.87 41 63 78 f100 5 lb 315 135 650 3.5 0.89 37 54 63 f50 6 f 360 90 640 5 0.87 44 65 80 f100 7 f 315 135 660 4 0.90 42 60 69 f50 8 a 360 90 625 5 0.86 44 65 79 f100 9 a 315 135 645 4 0.87 42 60 70 f50 10 g 360 90 620 5 0.85 43 64 78 f100 11 g 315 135 630 4.5 0.86 41 62 70 f50 12 wa 360 90 615 5 0.84 43 62 73 f100 13 wa 315 135 620 4 0.85 39 60 61 f50 14 ca 360 90 610 5 0.83 48 68 81 f100 15 ca 315 135 605 4 0.84 46 64 73 f50 48 corinaldesi v., gnappi g., moriconi g., montenero a. 2005. reuse of ground waste glass as aggregate for mortars. waste management, 25(2), 197–201. http://dx.doi.org/10.1016/j.wasman.2004.12.009 damtoft j. s., herfort d., yde e. 1999. concrete binders, mineral additions and chemical admixtures: state of the art and challenges for the 21st century, creating with concrete, thomas telford publishing, london, uk, 153–168. davidovits j. 1999. global warming impact on the cement and aggregates industries, world resources review, vol. 6, no.2, 263–278. day r. l., shi c. 1994. influence of fineness of pozzolan on the strength of lime natural-pozzolan cement pastes. cement and concrete research, vol. 24, 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michigan: american concrete institute, 1-12 / online http://www.columbia.edu/cu/civileng/meyer/publications/ publications/2002_04_shahpaper.pdf meyer c. 2009. the greening of the concrete industry, cement and concrete composites, vol. 31(8), 601–605. http://dx.doi.org/10.1016/j.cemconcomp.2008.12.010 park s. b, lee b. c, kim j. h. 2009. studies on mechanical properties of concrete containing waste glass aggregate. cement and concrete research, 34(12), 2181–2189. http://dx.doi.org/10.1016/j.cemconres.2004.02.006 rakshvir m., barai s. v. 2006. studies on recycled aggregatesbased concrete. waste management research 24(3), 225–33. http://dx.doi.org/10.1177/0734242x06064820 shao y, lefort t., moras s., rodriguez d. 2000. studies on concrete containing ground waste glass. cement and concrete research, vol. 30(1), 91–100. http://dx.doi.org/10.1016/s0008-8846(99)00213-6 schwarz n., neithalath n. 2008. influence of a fine glass powder on cement hydration: comparison to fly ash and modeling the degreeof hydration. cement and concrete composites, vol. 30, 486–96. http://dx.doi.org/10.1016/j.cemconcomp.2008.02.001 shi c., day r. l. 2001. comparison of different methods for enhancing reactivity of pozzolans. cement and concrete research, vol. 31, 813–818. http://dx.doi.org/10.1016/s0008-8846(01)00481-1 statistical report on packaging waste and recovery in the republic of latvia in 2003 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2005, 11 p. statistical report on packaging waste and recovery in the republic of latvia in 2004 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2006, 11p. statistical report on packaging waste and recovery in the republic of latvia in 2005 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2007, 11 p. statistical report on packaging waste and recovery in the republic of latvia in 2006 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2008, 11 p. statistical report on packaging waste and recovery in the republic of latvia in 2007 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2009, 11 p. statistical report on packaging waste and recovery in the republic of latvia in 2008 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2010, 11 p. statistical report on packaging waste and recovery in the republic of latvia in 2009 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2011, 11 p. statistical report on packaging waste and recovery in the republic of latvia in 2010 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2012, 12 p. statistical report on packaging waste and recovery in the republic of latvia in 2011 according to the european commission decision 2005/270/ec, riga, the ministry of environmental protection and regional development, 2013, 12 p. veidmane k., valiukaite v., morkvenas z., dudutyte z. 2004. waste management in the baltic states, 60 p. гост 10060.0-95 бетоны. методы определения морозостойкости. общие требования [concretes. methods for the determination of frost-resistance. general requirements] гост 10060.1-95 бетоны. базовый метод определения морозостойкости [concretes. basic method for the determination of frost-resistance] гост 10060.2-95 бетоны. ускоренные методы определения морозостойкости при многократном замораживании и 49 оттаивании [concretes. rapid method for the determination of frost-resistance by repeated alternated freezing and thawing] гост 26134-84 бетоны. ультразвуковой метод определения морозостойкости [concretes. ultrasonic method of frost resistance determination] received 2014 01 05 accepted after revision 2014 02 16 patricija kara – scientific researcher, lecturer at riga technical university, institute of materials and structures, department of building materials and products. rilem affiliate member, tc 219-acs and tc 225-sap. member of lvs stk 30 eurocode sub-committee. main research area: concrete technology, waste glass recycling, recycling of industrial wastes and by-products in concrete, environmental management, eco-construction materials. address: 1 kalku str., riga lv-1658, latvia. tel.: +371 670 89243 e-mail: patricija.kara@rtu.lv journal of sustainable architecture and civil engineering 2019/1/24 78 *corresponding author: delphine.bard@construction.lth.se acoustic comfort investigation in residential timber buildings in sweden received 2018/11/29 accepted after revision 2019/02/11 journal of sustainable architecture and civil engineering vol. 1 / no. 24 / 2019 pp. 78-89 doi 10.5755/j01.sace.24.1.22068 acoustic comfort investigation in residential timber buildings in sweden jsace 1/24 http://dx.doi.org/10.5755/j01.sace.24.1.22068 delphine bard*, lund university, lth, department of technical acoustics, john ericssons väg 1, lund, sweden saint-gobain nordic & baltic delegation, robert jacobsens vej 62a, 2300 københavn s denmark nikolaos-georgios vardaxis lund university, lth, department of technical acoustics, john ericssons väg 1, lund, sweden elin sondergard saint-gobain nordic & baltic delegation, robert jacobsens vej 62a, 2300 københavn s denmark introduction this article presents parts of a wide survey on acoustic comfort in swedish family buildings, specifically with focus on timber light-weight buildings. the scope of the whole research is to investigate acoustic comfort dimensions after collecting and combining data from standardized acoustic measurements and subjective responses from a questionnaire survey. certain noise sources were reported as dominant within living environments, impact noise from neighbors being the most important. installation noise from inside the building and outdoor low-frequency noise disturb also a lot. however, the overall level of acoustic comfort in contemporary wooden buildings seems satisfactory. keywords: acoustic comfort, field measurements, noise annoyance, subjective responses. this article concerns investigation of acoustic comfort in contemporary swedish timber buildings. the results presented are part of a wider research project about acoustic comfort in family apartments in sweden, including timber structures as well as typical heavy-weight concrete or mixed structure types (e.g. steel and concrete). to implement this study data from standardized acoustic measurements in the sample building structures were utilized. then an acoustic survey was setup for the residents of the test buildings: they were invited to fill in a questionnaire in their living environment. the overall scope of the research project is to collect and combine acoustic data and subjective responses from residents in order to develop approaches for the concept of acoustic comfort. the only description offered for the concept of acoustic comfort in the existing literature is the following: “a concept characterized by absence of unwanted sound, desired sounds with the right level and quality, opportunities for acoustic activities without annoying other people” as stated by rasmussen and rindel (2010). we would also add in that definition: “a concept with opportunities for supportive acoustic conditions according to the activities taking place”. for instance, different demands for acoustic conditions in a flat exist when residents cook, sleep, read or play the piano. furthermore, the above statements describe how acoustic comfort is relevant to a person as a receiver of sound and a source: somebody can be disturbed by noise from others or by their own 79 journal of sustainable architecture and civil engineering 2019/1/24 methods sounds or by the idea that they might disturb others around them. consequently, there can be conflicts or discomfort due to various situations related to noise sound in living environments. current standardized methods for airborne sound reduction and impact noise measurements have been used to assess sound insulation of building components (iso717 1996, iso140 1998, iso16283 2014, en iso12354 2017) but also as means to evaluate acoustic comfort in flats. as we analyzed in a review paper of relevant building acoustic surveys (vardaxis et.al. 2018), the measured descriptors derived from the iso standard measurements are highly associated to the subjective noise annoyance responses of the residents in multistory buildings. however, the acoustic indicators represent sound transmission between building elements, they do not represent directly any acoustic comfort index. for this research project we have setup a questionnaire design which includes noise annoyance from several sources in buildings alongside other important variables such as: size of home, living density in flats, characterization and emotional reaction to acoustic conditions at home and demographic data. in this article we present parts of the collected data with a main focus on noise annoyance in timber buildings; we demonstrate results of the whole sample which includes concrete buildings too, for a comparison of the differences regarding the wooden structures. our research design includes 101 different building units (different addresses) of 34 different structures types: concrete or timber buildings and mixed structures. thus the sample of buildings is 34 blocks (1 or more units each) with different structures: 25 hw buildings, 7 lw and 2 mixed structures: the term heavy-weight (hw) refers to concrete buildings and the term light-weight (lw) refers to wooden buildings. hw have a structure with concrete beams, floor and support walls: they can have concrete panels, brick walls (any kind or brick) or prefabricated panels (concrete, heavy or light) for walls. lw have wooden beams, floor and support walls: they utilize wooden elements, light bricks or prefabricated light-weight panels for wall components. fig. 1 impact sound levels l’n,w (left) and airborne sound reduction levels r’w (right) for all sample buildings of the research project: hw buildings with purple lines, lw wooden buildings with bold black lines 2 iso16283 2014, en iso12354 2017) but also as means to evaluate acoustic comfort in flats. as we analyzed in a review paper of relevant building acoustic surveys (vardaxis et.al. 2018), the measured descriptors derived from the iso standard measurements are highly associated to the subjective noise annoyance responses of the residents in multistory buildings. however, the acoustic indicators represent sound transmission between building elements, they do not represent directly any acoustic comfort index. for this research project we have setup a questionnaire design which includes noise annoyance from several sources in buildings alongside other important variables such as: size of home, living density in flats, characterization and emotional reaction to acoustic conditions at home and demographic data. in this article we present parts of the collected data with a main focus on noise annoyance in timber buildings; we demonstrate results of the whole sample which includes concrete buildings too, for a comparison of the differences regarding the wooden structures. methods our research design includes 101 different building units (different addresses) of 34 different structures types: concrete or timber buildings and mixed structures. thus the sample of buildings is 34 blocks (1 or more units each) with different structures: 25 hw buildings, 7 lw and 2 mixed structures: the term heavy-weight (hw) refers to concrete buildings and the term light-weight (lw) refers to wooden buildings. hw have a structure with concrete beams, floor and support walls: they can have concrete panels, brick walls (any kind or brick) or prefabricated panels (concrete, heavy or light) for walls. lw have wooden beams, floor and support walls: they utilize wooden elements, light bricks or prefabricated light-weight panels for wall components. figure 1: impact sound levels 𝐋𝐋𝐋𝐧𝐧𝐧𝐧𝐧 (left) and airborne sound reduction levels 𝐑𝐑𝐋𝐧𝐧 (right) for all sample buildings of the research project: hw buildings with purple lines, lw wooden buildings with bold black lines. following the european or iso standards and previous research (negreira 2016, hagberg 2018, ljungren et.al. 2014, hagberg and bard 2014), sound transmission was measured between two typical adjacent rooms, one above another, always bedrooms or living rooms, typical of the building’s floor plan and representative of everyday acoustic conditions. the room above is the sending test room and the one below is the receiving test room; that acoustic data included airborne sound measurements (sound speaker source above, microphone positions below), impact sound measurements (standardized tapping machine or other impact sources above, microphone positions 50 63 80 100 125 160 200 250 315 400 500 630 800 1k 1.25k 1.6k 2k 2.5k3.15k 4k 5k frequency bands in hz 0 10 20 30 40 50 60 70 80 im p a ct s o u n d le ve ls in d b measurement curves of impact sound level 50 63 80 100 125 160 200 250 315 400 500 630 800 1k 1.25k 1.6k 2k 2.5k3.15k 4k 5k frequency bands in hz 20 30 40 50 60 70 80 90 a ir b o rn e s o u n d le ve ls in d b measurement curves of airborne sound level following the european or iso standards and previous research (negreira 2016, hagberg 2018, ljungren et.al. 2014, hagberg and bard 2014), sound transmission was measured between two typical adjacent rooms, one above another, always bedrooms or living rooms, typical of the building’s floor plan and representative of everyday acoustic conditions. the room above is the sending test room and the one below is the receiving test room; that acoustic data included airborne sound measurements (sound speaker source above, microphone positions below), impact sound measurements (standardized tapping machine or other impact sources above, microphone positions below) and reverberation time measurements (impulse response measurement with sound source and microphones in the same test room) for the receiving room. journal of sustainable architecture and civil engineering 2019/1/24 80 fig. 1 presents the measurement curves for impact sound levels l’n,w and airborne sound reduction levels r’w for all sample structures. hw concrete buildings follow a similar trend with less dispersion around that except few cases of much higher or lower performance, especially in cases of impact sound which is the most critical for acoustic comfort (hagberg 2018, ljungren et.al. 2014). for the lw curves the behavior is dissimilar, with wider dispersion between them in the whole frequency range for both cases of impact and airborne sound. however, the highest and lowest values in curves belong mostly to hw cases, as can be seen in fig. 1 and also table 1. impact sound index in db airborne sound reduction index in db l’n,w l’n,w + c50-2500 l’n,w + c100-2500 r’w r’w + c50-3150 r’w + c100-3150 type: n mean (range) mean (range) heavy-weight (hw) 25 50 (38-64) 50.2 (40-65) 49.7 (39-64) 59.3 (46-67) 57.7 (44-64) 58.1 (44-65) light-weight (lw) 7 48.8 (45-55) 52.4 (49-59) 49.6 (47-54) 58.1 (48-68) 55.5 (48-63) 56.4 (48-65) all structures 34 49.8 (38-64) 50.8 (40-65) 49.7 (39-64) 59 (46-68) 57.2 (44-64) 57.6 (44-65) table 1 presents some statistics for the single number quantities for the sample measurements, the indices for airborne and impact sound characterization calculated according to the relevant iso standards. note that measurements in this study have a frequency range between 50-5000hz and the single number indices are calculated from 50 hz, which is the standard requirement in scandinavia. most data were acquired by a national swedish research database: the green building database. the building regulations in sweden demand a minimum level of sound level difference of d’nt,w,50 = 52 db from the space outside to inside a dwelling and highest impact sound levels of l’nt,w,50 = 56 db. those descriptors are equal to r’w +c50-3150 and l’n,w +c50-2500 respectively when no flanking transmission has been measured. however, other european countries have not that strict limits while the official requirement of the iso standard is 100-3150hz for airborne sound and 100-2500hz for impact sound measurements (boverket, 2016). furthermore, self-reported data was collected with the development of a social survey, using a questionnaire for the residents developed according to (iso-15666 2003). the survey aimed to capture several aspects that we consider part of the overall acoustic comfort concept: there is special focus on targeting all possible noise types and other variables relevant to noise annoyance. the questionnaire was distributed using post mail (one copy for every test flat, a web link was provided too): an invitation letter was sent first with the questionnaire, then two reminder letters followed within a month. the questions analyzed in this article are presented in table 2, with some statistics which refer to the subjects (residents) living in lw wooden buildings only. the subjects sample have an age span of 18-85 years and have spent at least 12 months in their flat, which were basic requirements for the survey. also they should have normal hearing, thus subjects who use hearing aids at home were filtered out of the data. tenants who live on the top floor were filtered out too, since they do not have neighbors on the floor above and their perception of noise annoyance is probably different. finally, after filtering, 85 responses for lw subjects were collected: 37 male, 45 female (3 did not report gender). the gender distribution was the same for the 375 subjects of the total sample (lw and hw) split in 43% men and 55% women. the overall response rate was 28% in both cases of lw and hw buildings. fig. 2 presents the distribution of observations in the overall research sample grouped by structure blocks, so one can see hw and lw observations together. table 1 single number quantities of acoustic descriptors for the sample buildings 81 journal of sustainable architecture and civil engineering 2019/1/24 the distribution of our observations grouped in different structures (or building blocks) is uneven: most blocks have less than 10 observations. however, 5 hw and 1 lw blocks, have 50% of the total observations (187 out of 375). for the case of lw wooden structures, a certain structure provided 59% of the total lw sample: that was a building block of 4 building units (8 separate addresses) of the exact same wooden structure type. fig. 2 histogram of the total research sample: observations grouped in building blocks and different structure types 4 of observations in the overall research sample grouped by structure blocks, so one can see hw and lw observations together. figure 2: histogram of the total research sample: observations grouped in building blocks and different structure types. the distribution of our observations grouped in different structures (or building blocks) is uneven: most blocks have less than 10 observations. however, 5 hw and 1 lw blocks, have 50% of the total observations (187 out of 375). for the case of lw wooden structures, a certain structure provided 59% of the total lw sample: that was a building block of 4 building units (8 separate addresses) of the exact same wooden structure type. results and discussion histograms of questions 1-3 are illustrated in figure 3. as can be observed, most subjects stayed at their house for 1-5 years, about 71% while only 9% have lived for more than 10 years. that situation is indicative of mobility in swedish apartments since there are new buildings erected and inhabited, while in parallel a shortage of house supply makes lots of tenants to rely on short-term rentals and move frequently between rented flats. for the lw cases, tenants have evenly spent from 1-10 years in the building but the wooden structures of our sample are contemporary: the oldest one was finished and occupied in 2008. question 2 (fig. 3) concerns apartment size (in square meters): the distribution of this variable is close to normal, with most flats being between 60 and 80 sq., one third of the total sample. for the wooden buildings case, this is still true: 32 of the 85 lw flats are between 60-80 sq. (ca. 38%) but the overall lw data concern bigger flats. for instance, 37% of the lw flats are bigger than 80 sq. which can be justified as wooden buildings in sweden are new and have bigger size. the number of flat tenants is important for the parameter of living density. as illustrated in question 3 (fig. 3) one or two persons live in most flats in both hw and lw structures, while only 20% of the cases concern 3 tenants or more in a flat. for wooden buildings, it is only 12% of flats with 3 or more tenants, while 34 persons live alone (40%). then, question 4 deals with the presence of children in the house, which is an important factor for the status of the tenants (family with children at home), the living density and the possible presence of noise at their own home due to children. overall, 23% of the survey flats have children at home, while for the wooden buildings sample this percentage is almost half namely 14% (12 out of 85). question 5 aimed at nuisances that affect the decisions of the tenants that much as to move out from a residency. about 8% of the total subjects would consider moving out due to noise pollution in their living environment: this corresponds to a small percentage for lw buildings (only 2%) but a considerable percentage for hw concrete buildings (9%). that is a first indication that wooden 0 5 10 15 20 25 30 35 sample building block index 0 10 20 30 40 50 n u m b er o f o bs e rv a tio n s mixed structures hw: heavyweight lw: lightweight histograms of questions 1-3 are illustrated in fig. 3. as can be observed, most subjects stayed at their house for 1-5 years, about 71% while only 9% have lived for more than 10 years. that situation is indicative of mobility in swedish apartments since there are new buildings erected and inhabited, while in parallel a shortage of house supply makes lots of tenants to rely on short-term rentals and move frequently between rented flats. for the lw cases, tenants have evenly spent from 1-10 years in the building but the wooden structures of our sample are contemporary: the oldest one was finished and occupied in 2008. question 2 (fig. 3) concerns apartment size (in square meters): the distribution of this variable is close to normal, with most flats being between 60 and 80 sq., one third of the total sample. for the wooden buildings case, this is still true: 32 of the 85 lw flats are between 60-80 sq. (ca. 38%) but the overall lw data concern bigger flats. for instance, 37% of the lw flats are bigger than 80 sq. which can be justified as wooden buildings in sweden are new and have bigger size. the number of flat tenants is important for the parameter of living density. as illustrated in question 3 (fig. 3) one or two persons live in most flats in both hw and lw structures, while only 20% of the cases concern 3 tenants or more in a flat. for wooden buildings, it is only 12% of flats with 3 or more tenants, while 34 persons live alone (40%). then, question 4 deals with the presence of children in the house, which is an important factor for the status of the tenants (family with children at home), the living density and the possible presence of noise at their own home due to children. overall, 23% of the survey flats have children at home, while for the wooden buildings sample this percentage is almost half namely 14% (12 out of 85). question 5 aimed at nuisances that affect the decisions of the tenants that much as to move out from a residency. about 8% of the total subjects would consider moving out due to noise pollution in their living environment: this corresponds to a small percentage for lw buildings (only 2%) but a considerable percentage for hw concrete buildings (9%). that is a first indication that wooden multistory residencies in sweden can offer better acoustic conditions compared to typical concrete structures, but they were also designed to fulfil higher acoustic criteria. questions 6 and 7 refer to noise sources unmentioned in the questionnaire but might be of concern for the residents in the survey buildings. specifically, 20% of hw and 22% of lw tenants have alternative sources of disturbance in question 6. question 7 shows that 56% of those replied being somewhat or fairly annoyed. additionally, about 30% of those commented on the nature of the additional source: most of them referred to construction noise from building sites next to their house. that refers to a common situation in swedish housing where new buildings are constructed or existing ones get renovated, thus there are many construction sites producing noise next to dwellresults and discussion journal of sustainable architecture and civil engineering 2019/1/24 82 table 2 questionnaire data and initial statistics for the wooden building sample questions n: replies mean std. 1. how long have you lived in your home? (years) 83 5.96 4.11 2. what is the size of your home? (in square meters) 72 80.10 16.78 3. how many people, including you, are currently living in your home? 80 1.73 0.75 4. do you have children living with you on a regular basis? (1:no, 2:yes) 81 1.15 0.36 5. are you considering moving from your home due to noise pollution? (1:no, 2:yes) 83 1.02 0.15 6. is there any other disturbing source of noise in or close to your home that we have not addressed? (1:no, 2:yes) 84 1.22 0.42 7. if so, please indicate the level of disturbance: (1:not at all, 2:slightly, 3:moderately, 4:very, 5:extremely) 23 1.91 0.85 8. how pleased are you with the sound environment in your home? (1:very pleased, 2:fairly pleased, 3:neither pleased or displeased, 4:fairly displeased, 5:very displeased) 81 1.75 1.06 9: thinking about the last 12 months, when you are here at home… 9.a. how much do you think about not disturbing your neighbours when you e.g. play music, close doors, or walk around? 82 2.34 1.09 9.b. how disturbed/bothered do you think your neighbours are from the noise you make? (1:not at all, 2:slightly, 3:moderately, 4:very, 5:extremely) 82 1.26 0.58 10: thinking about the last 12 months, when you are here at home, with the windows and doors shut, how much disturbed are you by: 10.a. noise from machines or appliances inside the building? (refrigerator, freezer, washer, dryer, lift, ac, ventilation, water pipes, flushing toilets) 82 1.86 0.78 10.b. low-frequency noise from a neighbour’s sound system, tv or computer, coming through the walls? 82 1.21 0.51 10.c. low-frequency noise from a neighbour’s sound system, tv or computer, coming through the floor or ceiling? 81 1.42 0.69 10.d. sound of neighbours talking, coming through the walls? 82 1.07 0.47 10.e. sound of neighbours talking, coming through the floor or ceiling? 81 1.22 0.63 10.f. sound of neighbours walking, slamming doors and dropping things, thuds from children playing, coming through the floor or ceiling? 82 2.04 1.01 10.g. sound of walking in shared spaces of the building (staircase, hallway, etc.)? 82 1.40 0.78 10.h. low-frequency noise (rumbling, muffled sound) from outside sources such as music, traffic and ventilation? (1:not at all, 2:slightly, 3:moderately, 4:very, 5:extremely) 82 1.67 0.77 11: how would you rate your normal quality of sleep? (1:very good, 2:good, 3:neither good or bad, 4:bad, 5:verybad) 82 2.26 1.05 12: in a regular week, how often does noise disturb your sleep? (1:not at all, 2:1-2 times/week, 3:3-4 times/week, 4:5-6 times/week, 5:every night) 83 1.35 0.88 13: thinking about the last 12 months, when you are here at home with the windows and doors shut, how much is your sleep disturbed by: 13.a. noise from machines or appliances inside the building? (refrigerator, freezer, washer, dryer, lift, ac, ventilation, water pipes, flushing toilets) 84 1.33 0.55 13.b. low-frequency noise from a neighbour’s sound system, tv or computer? 84 1.11 0.35 13.c. sound of neighbours talking? 84 1.10 0.48 13.d. sound of neighbours walking, slamming doors and dropping things, thuds from children playing? 84 1.52 0.87 13.e. sound of walking in shared spaces of the building (staircase, hallway, etc.)? 84 1.24 0.70 13.f. low-frequency noise (rumbling, muffled sound) from outside sources such as music, traffic and ventilation? (1:not at all, 2:slightly, 3:moderately, 4:very, 5:extremely) 84 1.33 0.71 14. age (derived from the question “what year where you born?”) 82 58 19.13 15. what is your highest completed level of education? (1:primary school, : high school, 3:college/university) 83 2.34 0.8 16.what is your current occupation? (1:student, 2:stay at home, 3:on sick leave, 4:leave of absence, 5:unemployed, 6:employed currently, 7:other) 83 6.25 1.14 83 journal of sustainable architecture and civil engineering 2019/1/24 ings. other additional noise types were unidentified installation noise and machinery noise (e.g. few tenants commented on some noise types that sound like washing machine or ventilation). the satisfaction related to the acoustic living environment has been included as a variable (question 8, fig. 3) which has been used in past surveys too (bradley 2001, hongisto et.al. 2015). as illustrated up to 77% of subjects are very pleased or fairly pleased with their sound climate, only 11% are fairly or very displeased. for lw buildings the satisfaction ratings are even better with 80% of lw tenants being fairly or very pleased and 11% being fairly displeased. fig. 3 questions 1-3 and 8. histograms of questionnaire replies grouped in different structure types for the sample buildings 6 (1:student, 2:stay at home, 3:on sick leave, 4:leave of absence, 5:unemployed, 6:employed currently, 7:other) 1. how long have you lived in your home? 2. what is the size of your home? 3. how many people, including you, are currently living in your home? 8. how pleased are you with the sound environment in your home? figure 3: questions 1-3 and 8. histograms of questionnaire replies grouped in different structure types for the sample buildings. questions 6 and 7 refer to noise sources unmentioned in the questionnaire but might be of concern for the residents in the survey buildings. specifically, 20% of hw and 22% of lw tenants have all structures 0 10 20 30 40 0 20 40 60 80 100 120 140 160 180 n u m b er o f o bs e rv a tio n s hw 0 10 20 30 40 years 0 20 40 60 80 100 120 140 160 180 lw 0 10 20 30 40 0 20 40 60 80 100 120 140 160 180 all structures 0 50 100 150 200 0 10 20 30 40 50 60 70 80 n u m b e r o f o b se rv a tio n s hw 0 50 100 150 200 size in sq.m. 0 10 20 30 40 50 60 70 80 lw 0 50 100 150 200 0 10 20 30 40 50 60 70 80 all structures 0 2 4 6 8 0 20 40 60 80 100 120 140 160 n u m b e r o f o b se rv a tio n s hw 0 2 4 6 8 number of flat tenants 0 20 40 60 80 100 120 140 160 lw 0 2 4 6 8 0 20 40 60 80 100 120 140 160 all structures 1 2 3 4 5 0 10 20 30 40 50 n u m b e r o f o b se rv a tio n s hw 1 2 3 4 5 questionnaire replies in scale: 1:very pleased, 2:fairly pleased, 3:neither pleased or displeased, 4:fairly displeased, 5:very displeased 0 10 20 30 40 50 lw 1 2 3 4 5 0 10 20 30 40 50 questions 9.a and 9.b, fig. 4, are inspired by the definition of acoustic comfort provided by rasmussen and rindel (2010) and relate to the perception of oneself as a source of noise for others. in 9.a. tenants self-reported that they think, up to some extend, about not causing noise annoyance to their neighbors their own activities. specifically, 47% of the total subjects replied that they think journal of sustainable architecture and civil engineering 2019/1/24 84 moderately, very or extremely about not disturbing their neighbors. but the lw percentage is lower at 34%; this happens probably due to increased acoustic comfort sense in wooden buildings so the residents have to think less about noise annoyance in general, both as receivers or sources of noise. then in 9.b the majority of subjects think that their neighbors are not at all or slightly disturbed by the noise they make: this applies for 93% of the total subjects and 100% of the lw tenants. in fig. 5 all the histograms of replies in question module 10 are presented, regarding daytime noise annoyance at home and which noise sources cause higher disturbances. the annoyance ratings were given in a likert type 5-point-scale with the range: 1-not at all, 2-slightly, 3-moderately, 4-very, 5-extremely. specifically, in 10.a. it can be observed that 51% of lw tenants reported slightly annoyed by machine and installations noise (e.g. washing machine, dryer, water pipes, flushing toilets) in their flat, 33% not at all and 14% are moderately to extremely annoyed. for question 10.b. (fig. 5) just 14% of the lw tenants are slightly disturbed by neighbors’ low-frequency noise propagating through walls while only 2% are moderately to extremely annoyed. thus, those neighbors’ low-frequency noise types seem to create bigger disturbances through floors in apartments. in question 10.d. (fig. 5) it seems that 93% of lw tenants are not at all annoyed by neighbors’ talking coming through walls and in 10.e. as well 81% of lw tenants replied as not at all annoyed by neighbors’ airborne noise propagating through floors (9% are slightly disturbed, 5% are moderately to extremely annoyed). that is another indication of high acoustic comfort with sufficient airborne sound insulation in swedish timber buildings. (80% not at all disturbed, few did not reply). for the same question of sound transmission but through floors, in 10.c, 28% of lw tenants reported slightly annoyed by neighbors’ low-frequency noise propagating through floors while 5% are moderately to extremely annoyed (62% not at all). impact noise (stepping, kids playing, slamming doors dropping objects) propagating through floors is one of the typical disturbances in family building apartments, known by many previous studies (vardaxis et.al.). in question 10.f. in fig. 5, the 46% of the tenants self-reported as slightly annoyed by neighbors’ impact sounds while 20% report moderately to extremely annoyed. further, in question 10.g. can be observed that 20% of lw tenants are slightly annoyed by noise in shared spaces (hallway, staircases) and 7% are moderately to extremely annoyed. finally, 10.h. concerns outside low-frequency noise (such as traffic, music, ventilations) for which the responses suggest that 44% of lw tenants are slightly annoyed while 8% are moderately to extremely annoyed: that is another significant high response for a known noise source. questions 11, 12 and 13 in fig. 6 comprise the module in the questionnaire regarding noise annoyance during sleep; it includes the same questions as module question 10 without differentiation 7 alternative sources of disturbance in question 6. question 7 shows that 56% of those replied being somewhat or fairly annoyed. additionally, about 30% of those commented on the nature of the additional source: most of them referred to construction noise from building sites next to their house. that refers to a common situation in swedish housing where new buildings are constructed 9.a. how much do you think about not disturbing your neighbours when you e.g. play music, close doors, or walk around? 9.b. how disturbed/bothered do you think your neighbours are from the noise you make? questionnaire replies in scale: 1:not at all, 2:slightly, 3:moderately, 4:very, 5:extremely. figure 4: questions 9.a and 9.b. histograms of questionnaire replies for the subjects residing in wooden buildings. or existing ones get renovated, thus there are many construction sites producing noise next to dwellings. other additional noise types were unidentified installation noise and machinery noise (e.g. few tenants commented on some noise types that sound like washing machine or ventilation). the satisfaction related to the acoustic living environment has been included as a variable (question 8, figure 3) which has been used in past surveys too (bradley 2001, hongisto et.al. 2015). as illustrated up to 77% of subjects are very pleased or fairly pleased with their sound climate, only 11% are fairly or very displeased. for lw buildings the satisfaction ratings are even better with 80% of lw tenants being fairly or very pleased and 11% being fairly displeased. questions 9.a and 9.b, figure 4, are inspired by the definition of acoustic comfort provided by rasmussen and rindel (2010) and relate to the perception of oneself as a source of noise for others. in 9.a. tenants self-reported that they think, up to some extend, about not causing noise annoyance to their neighbors their own activities. specifically, 47% of the total subjects replied that they think moderately, very or extremely about not disturbing their neighbors. but the lw percentage is lower at 34%; this happens probably due to increased acoustic comfort sense in wooden buildings so the residents have to think less about noise annoyance in general, both as receivers or sources of noise. then in 9.b the majority of subjects think that their neighbors are not at all or slightly disturbed by the noise they make: this applies for 93% of the total subjects and 100% of the lw tenants. in figure 5 all the histograms of replies in question module 10 are presented, regarding daytime noise annoyance at home and which noise sources cause higher disturbances. the annoyance ratings were given in a likert type 5-point-scale with the range: 1-not at all, 2-slightly, 3moderately, 4-very, 5-extremely. specifically, in 10.a. it can be observed that 51% of lw tenants reported slightly annoyed by machine and installations noise (e.g. washing machine, dryer, water pipes, flushing toilets) in their flat, 33% not at all and 14% are moderately to extremely annoyed. for question 10.b. (fig. 5) just 14% of the lw tenants are slightly disturbed by neighbors’ lowfrequency noise propagating through walls while only 2% are moderately to extremely annoyed.thus, those neighbors’ low-frequency noise types seem to create bigger disturbances through floors in apartments. 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m b e r o f o b se rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m b e r o f o b se rv a tio n s fig. 4 questions 9.a and 9.b. histograms of questionnaire replies for the subjects residing in wooden buildings 85 journal of sustainable architecture and civil engineering 2019/1/24 fig. 5 daytime noise annoyance, questions 10.a-10.h. histograms of questionnaire replies for the subjects residing in wooden buildings between horizontal and vertical sound transmission, i.e. from walls or floors respectively. question 11 concerns the quality of sleep of the subjects: 20% self-report to have a bad sleep while 68% report having good or very good sleep quality. however, bad sleep quality is not necessarily connected to acoustic conditions. then, question 12 records how often a subject is annoyed during sleep by any noise: 11% reported disturbed 1-2 times per week and 8% at least 3-4 times per week (79% not at all). as observed by replies in question 13.a 13.f in fig. 6, the same types of noise affect daytime and sleeping time response towards noise disturbance. specifically, machinery/installations noise 8 daytime noise annoyance questions 10.a. noise from machines or appliances inside the building? (refrigerator, freezer, washer, dryer, lift, ac, ventilation, water pipes, flushing toilets) 10. b. low-frequency noise from a neighbour’s sound system, tv or computer, coming through the walls 10.c. low-frequency noise from a neighbour’s sound system, tv or computer, coming through the floor or ceiling 10.d. sound of neighbours talking, coming through the walls 10.e. sound of neighbours talking, coming through the floor or ceiling 10.f. sound of neighbours walking, slamming doors and dropping things, thuds from children playing, coming through the floor or ceiling 10.g. sound of walking in shared spaces of the building (staircase, hallway, etc.)? 10.h. low-frequency noise (rumbling, muffled sound) from outside sources such as music, traffic and ventilation? questionnaire replies in scale: 1:not at all, 2:slightly, 3:moderately, 4:very, 5:extremely. figure 5: daytime noise annoyance, questions 10.a-10.h. histograms of questionnaire replies for the subjects residing in wooden buildings. 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s journal of sustainable architecture and civil engineering 2019/1/24 86 fig. 6 sleeping time noise annoyance, questions 11-13.h. histograms of questionnaire replies for the subjects residing in wooden buildings 9 questionnaire replies in scale: 1:not at all, 2:slightly, 3:moderately, 4:very, 5:extremely. figure 5: daytime noise annoyance, questions 10.a-10.h. histograms of questionnaire replies for the subjects residing in wooden buildings. sleeping time noise annoyance questions 11. how would you rate your normal quality of sleep? 12. in a regular week, how often does noise disturb your sleep? 13.a. noise from machines or appliances inside the building? (refrigerator, freezer, washer, dryer, lift, ac, ventilation, water pipes, flushing toilets) 13.b. low-frequency noise from a neighbour’s sound system, tv or computer? 13.c. sound of neighbours talking? 13.d. sound of neighbours walking, slamming doors and dropping things, thuds from children playing? 13.e. sound of walking in shared spaces of the building (staircase, hallway, etc.)? 13.f. low-frequency noise (rumbling, muffled sound) from outside sources such as music, traffic and ventilation? 1 2 3 4 5 1:very good, 2:good, 3:neither good or bad, 4:bad, 5:very bad 0 10 20 30 40 50 60 70 80 n um b er o f o bs er va tio n s 1 2 3 4 5 1:not at all, 2:1-2 times/week, 3:3-4 times/week, 4:5-6 times/week, 5:every night 0 10 20 30 40 50 60 70 80 n um b er o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s 1 2 3 4 5 replies 0 10 20 30 40 50 60 70 80 n u m be r o f o bs e rv a tio n s (26% slightly annoyed, 3% at least moderately-extremely annoyed) alongside neighbor’s impact noise (25% reported slightly annoyed, 9% moderately-extremely) and outside low-frequency noise (15% slightly and 6% at least moderately annoyed. furthermore, some personal and socioeconomic data was gathered in the questionnaire as well. regarding question 14, the distribution of age for the whole sample is close to a balance where at least 40 observations exist for every category of ages between 20-80 years old. only subjects of age 18-85 years old were allowed to take part in the study. about 40% of the total subjects are below 40 years old, 30% are between 40-60 and 30% are older than 60. however, residents of lw 87 journal of sustainable architecture and civil engineering 2019/1/24 buildings are older than hw buildings: specifically, 25% of lw residents are below 40 years old, 22% are between 40-60 and 53% are older than 60. the education status of tenants was recorded too: most subjects have completed university studies (53%) in both cases of hw (54%) and lw (53%) buildings. the occupation status is the topic of question 16: most participants are in the categories of currently employed or reported “other”, which mostly means pensioner as it was commented. again it is observed the for the total sample there are 57% employed tenants and 24% pensioners while for the lw buildings there is only 43% of currently working tenants and 48% of pensioners. this study presents data from a building acoustic survey in contemporary swedish structures: the aspects of acoustic comfort in wooden buildings are in the focus of the research, as well as relevant information on light-weight (lw) family residencies in sweden. the study sample of wooden buildings contains 7 different structures and questionnaire responses from 85 tenants. an overall level of high acoustic comfort is indicated by the self-reported data of lw tenants, with low annoyance responses and only few complaints about the acoustic environment at home. the timber buildings of our sample were maximum 10 years old at the time of the data collection; the swedish timber dwellings are also bigger than the average size suggested by a total research sample including many concrete structures. additionally, most lw residents live alone or with another tenant and only 14% of them have children at home. the situation is different in concrete hw buildings, were 23% of subject have children at home and the living density is higher. consequently, the practical conditions for lw tenants are better to ensure less noise annoyance from others inside their own flat. the self-reported satisfaction for lw buildings is very high: 80% of lw tenants being fairly or very pleased. summing up the noise types that cause the biggest annoyance for residents in the wooden buildings of our sample are: home machinery and installations, impact noise caused by neighbors and outside low-frequency noise; the latter concerns mostly noise sources such as road traffic (vehicle sounds), music from cars, shops, cafes, bars or outer installations such as ventilation from shops, restaurants etc. there is emphasis on the low frequency content of outside noise sounds because that can still propagate in the form vibrations inside apartments with closed windows and doors, while the middle and higher frequencies are usually filtered out from the building façade. additionally, if we consider that it is acceptable or at least unavoidable for some residents to be slightly annoyed by a certain noise type in their living environment then we could rank the most disturbing noise source according to the amount of subjects that self-report to be moderately, very or extremely annoyed. that would make sense since for the above three noise types the percentage of subjects reporting slightly annoyed varies between 44-51%, so there is no extreme difference in those cases for a sample of 85 subjects. consequently, impact noise from neighbors (through floors) would be summarized as the most important noise type (20%), home installations (14%) would be the second biggest annoyance and outside low-frequency noise would come third (8%). the questionnaire data indicates also some disturbance due to: low-frequency noise from neighbors’ sound system (tv or computer) through floors or ceilings and noise in common spaces of the building (corridors, staircases). all the analyzed noise disturbances are typical noise problems in living environments (ljungren et.al. 2014, ljungren et.al. 2017, vardaxis et.al. 2017). similar responses were recorded for sleeping time noise annoyance. most tenants did not report any sleep interruptions in swedish wooden buildings (79%) but some reported frequent annoyance during sleep (8%). with a ranking approach as before, impact noise from neighbors (through floors) remains the most important noise type (9%), outside low-frequency noise is second highest this time (6%) and installation noise comes third (3%). conclusions journal of sustainable architecture and civil engineering 2019/1/24 88 finally, it is important to notice that in our study sample the tenants of wooden buildings are of higher age (53% older than 60) than those in typical concrete swedish buildings; additionally, most of them are pensioners or not currently employed. thus there is an imbalance concerning age distribution in the lw sample presented here: it might not be representative of the whole population of wooden building tenants in sweden. boverket, boverket’s building regulations – mandatory provisions and general recommendations, bbr, sweden, boverket the swedish national board of housing, building and planning, 2016. bradley j.s., “deriving acceptable values for party wall insulation from survey results”, proceeding inter-noise 2001, hague, netherlands, 2001. en iso 12354 “building acoustics – estimation of acoustic performance of buildings from the performance of elements, – part 1: airborne sound insulation between rooms, – part 2 :impact sound insulation between rooms” (international organization for standardization, geneva, switzerland), 2017. hagberg k., bard d., “low frewquency sound transmission in multifamily wooden houses” inter-noise 2014, melbourne, australia, 2014. hagberg k., management of acoustics in lightweight structures, doctoral thesis, engineering acoustics, lth, lund university, 2018. hongisto v., mäkilä m., suokas m., satisfaction with sound insulation in residential dwellings – the effect of wall construction, building environment 86, 2015, 309-320. https://doi.org/10.1016/j.buildenv.2014.12.010 iso 140 “acoustics – measurement of sound insulation in buildings and of building elements, – 4:field measurements of airborne sound insulation between rooms, – 7:field measurements of impact sound insulation of building elements” (international organization for standardization, geneva, switzerland), 1998. iso 15666 “acoustics assessment of noise annoyance by means of social and socio-acoustic surveys” (international organization for standardization, geneva, switzerland), 2003. iso 16283 “field measurement of sound insulation in buildings and of building elements, part 1: airborne sound insulation, part 2: impact sound insulation” (international organization for standardization, geneva, switzerland), 2014. iso 717 “acoustics – rating of sound insulation in buildings and of buildings elements. – 1:airborne sound insulation, – 2:impact sound insulation” (international organization for standardization, geneva, switzerland), 1996. ljunggren f., simmons c., hagberg k., “correlation between sound insulation and occupants’ perception – proposal of alternative single number rating of impact sound”, applied acoustics 85, 2014, 57-68. https://doi.org/10.1016/j.apacoust.2014.04.003 ljunggren f., simmons c., hagberg k., “findings from the akulite project: correlation between measured vibro-acoustic parameters and subjective perception in lightweight buildings” proceedings inter-noise 2013, innsbruck, austria, 2013. ljunggren f., simmons c., öqvist r., “correlation between sound insulation and occupants’ perception – proposal of alternative single number rating of impact sound-part ii”, applied acoustics 123, 2017. https://doi.org/10.1016/j.apacoust.2017.03.014 ljunggren f., simmons c., öqvist r., “evaluation of impact sound insulation from 20hz”, proceedings 24th international congress on sound and vibration, icsv24, london, united kingdom, 2017. milford i., høsøien c.o., løvstad a., rindel j. h., klæboe r., “socio-acoustic survey of sound quality in dwellings in norway”, proceedings inter-noise 2016, hamburg, germany, 2016. negreira j., vibroacoustic performance of wooden buildings, doctoral thesis, engineering acoustics, lth, lund university, 2016. rasmussen b., rindel j.h., sound insulation between dwellings requirements in building regulations in europe, j. applied acoustics 71, 2010, 373-385. https://doi.org/10.1016/j.apacoust.2009.08.011 simmons c., chapter 6: developing a uniform questionnaire for socio-acoustic surveys in residential buildings. in: building acoustics throughout europe, vol. 1: towards a common framework in building acoustics throughout europe, 2013, 102-124. simmons c., hagberg k., backman e., “acoustical performance of apartment buildings – resident’s survey and field measurements”, akulite report 2 (2011), sp report 58, 2011. simmons c., ljunggren f., “aku20 – searching for optimal single number quantities in en iso 717-2 correlating field measurements 20-5000hz to occupant’s ratings of impact sounds – new findings for concrete floors”, euronoise 2015, maastricht, netherlands, 2015. references 89 journal of sustainable architecture and civil engineering 2019/1/24 vardaxis n.-g., bard d., persson waye k., review of acoustic comfort evaluation in dwellings – part i: associations of acoustic field data to subjective responses from building surveys, building acoustics, 25(2), 2018, 151–170. https://doi. org/10.1177/1351010x18762687 delphine bard associate professor lund university, lth, department of technical acoustics main research area building acoustics, room acoustics, noise and vibrations, physical modelling, auralization, acoustic laboratory management, standardized and experimental measurements address john ericssons väg 1, lund, sweden.tel. e-mail: delphine.bard@ construction.lth.se nikolaos-georgios vardaxis phd student lund university, lth, department of technical acoustics main research area building acoustics, room acoustics, architectural design, noise and vibrations, data analysis, statistical modelling, standardized and experimental measurements address john ericssons väg 1, lund, sweden.tel. e-mail: nikolas.vardaxis@ construction.lth.se elin sondergard manager for off-site construction saint-gobain nordic & baltic delegation main research area off-site construction address robert jacobsens vej 62a, 2300 københavn s, denmark. e-mail: elin.sondergard@saint-gobain.com about the authors journal of sustainable architecture and civil engineering 2021/1/28 56 *corresponding author: diana.bajare@rtu.lv investigation of social opinion on green lifestyle and ecofriendly buildings. decision making criteria received 2020/12/07 accepted after revision 2021/01/19 journal of sustainable architecture and civil engineering vol. 1 / no. 28 / 2021 pp. 56-71 doi 10.5755/j01.sace.28.1.28092 investigation of social opinion on green lifestyle and eco-friendly buildings. decision making criteria jsace 1/28 http://dx.doi.org/10.5755/j01.sace.28.1.28092 vladimirs šatrevičs, irina voronova riga technical university, kalnciema street, room 412, riga, lv-1048 diana bajare* institute of materials and structure, faculty of civil engineering, riga technical university introduction the present paper develops decision-making criteria through literature research to assess the social opinion on green life style and eco-friendly buildings. validity of criteria was ensured among company executives and academic staff, based on elaborated criteria small pilot survey was performed and analysed. current research focuses on the influence of demographic variables (e.g., age, gender) and individual subjective characteristic factors; external influencing factors (e.g., social norms, policies) are not used. according to the research results, our concept helps to outline the most crucial factors in industry regarding customer subjective requirements on eco-friendly building and innovative building materials. nowadays companies need to meet customer requirements in order to adjust them in terms of eco-innovation approach and industry’s green ecosystem development and remove the gaps in value preposition. this paper helps to investigate respondents’ awareness, requirements, and willingness-to-pay for the eco-friendly houses. keywords: sustainable development, eco-friendly-house, green life style awareness, eco-innovation, willingness to pay, eco-feedback eco-friendly homes need to be integrated with energy economical technologies to avoid wasting resources and increase customers` comfort. though the green-house technologies and assessment tools are utilized in the housing market, problems like cost, comfort and performance expectation issues in client behaviours should be disclosed. the aim of the study is to identify factors that influence the decision to choose green lifestyle, new eco-building materials and discuss them in focus groups in order to develop a valid questionnaire. the main task of the study is to develop a valid questionnaire for opinion assessment. the present research develops a questionnaire survey, investigates the willingness-to-pay (wtp) and awareness factors that have the influence on eco-friendly houses. respondents’ priorities and awareness towards eco-friendly houses: like eco design, air ventilation, sound protection, illumination, and also the management of house performance are known, analysed and discussed. according to the respondents’ awareness and factor priorities, along with behaviour model the conceptual guidance for eco-friendly developers, designers, and engineers in developing eco-house with best performance and price may well be elaborated. 57 journal of sustainable architecture and civil engineering 2021/1/28 the full research design is explained on fig.5, but shortly we built a conceptual model (fig. 2) for the questionnaire dimensions, then used systematic literature review as main methodology to elaborate criteria for the survey and validated them in focus groups (during 2 weeks, interviews among company executives and academic staff were conducted). the authors chose triangulation to ensure the research validity and reliability (data validation through expert focus groups, expert interviews, and feedback from pilot groups). after obtaining the survey questions, we conducted a small pilot study among respondents to ensure that all questions are finally valid and to have preliminary results for the upcoming big scale survey which will be performed later. our future research direction will be to identify correlations among factors. recycling and energy efficiency are the most contemporary approahes important for the european union green policy in order to enhance environmental sustainability (hinchliffe and akkerman 2017). in this context, engineering products with eco-efficiency, selection of environmental-friendly materials and technologies to meet requirements with a low environmental impact is extremely topical. so, there is an increased consideration of the design concept and material selection concurrently at the early stage of the product development (shqipe buzuku 2017). as a result, eco-design tools are necessary to minimize the environmental impact due to the product’s materials and related processes. but these tools need to satisfy customers and collaborate with the entrepreneurial ecosystem in order to create a circular economy. geissdoerfer (geissdoerfer et al. 2017) defined a circular economy as “a regenerative system in which resource input and waste, emission, and energy leakage are minimised by slowing, closing, and narrowing material and energy loops. this can be achieved through long-lasting design, maintenance, repair, reuse, remanufacturing, refurbishing, and recycling.” a circular economy is built upon industrial ecology, eco-efficiency, cradle-to-cradle manufacturing, as well as sustainable production and consumption (kuo and smith 2018). the provision of information about others’ energy consumption and one’s own performance, a process called eco-feedback, could thus improve household energy conservation (kuo et al. 2018). the collaborative environment with clusters of industrial technologies, materials and engineering reveals up possibilities to upgrade the eco-house practices of companies towards an customized innovation strategy requiring understanding of market demand structure. another objective of innovation strategies is to promote the increasing awareness of sustainable materials, using different activities like dissemination of results, virtual and physical user-experiences with models, prototypes and concepts (cicconi 2020). only several studies have been conducted to explore the relationship between eco-house factors and energy consumption behaviour (shen et al. 2020). however awareness and dissemination can raise residents’ sense of responsibility to increase energy efficiency to some level, but such efforts seldom translate into changing the responsible energy consumption of a customers (azar and al ansari 2017). usually in situation when individuals realize environmental impact and receive information on how to improve one’s own eco-behaviour, their could change their behaviour (asensio and delmas 2015). for instance, a study conducted in sweden showed that although households have awareness of the issue of energy conservation, they lack sufficient knowledge about how to reduce their energy consumption (vassileva and campillo 2014). many research shows that lifestyle and perceived value of comfort define an individual’s participation in energy-saving programs and products (thondhlana and kua 2016). overall eco-environmental behaviour and attitude is positively related to willingness to buy energy-efficient products (trotta 2018). in this paper, the research focuses on current awareness of sustainable materials and eco-building usability and maintenance. we also try to assess factors which customers find important when selecting appropriate building in order to provide guidance for eco-friendly house developers. the ecofriendly framework to provide a more precise understanding of the consumer behaviour towards eco-friendly products and services, we provide a concept analysis. the eco-innovation approach has been emphasized since the 1990s based on the concept presented by claude fussler and peter james (fussler 1996). these authors determined that eco-innovation is a ‘process of developing new products, journal of sustainable architecture and civil engineering 2021/1/28 58 processes, and services, which generates value for the company and for the customer, along with a reduction in environmental impact’ (den hond 1997). bitencourt (2020) sees eco-innovation as ‘research and contribution for ecological economics’ (bitencourt et al. 2020). they investigate the main drivers (capabilities and resources) and results (consumer value) of eco-innovation. another significant factor of ecological awareness – acknowledge of environmental impact of on ecosystems (carson 1962), is one of the aspects which affects consumers’ decision. we have a practical approach to consumer choices; consumer behavior research could be concentrated more on studying actual product decision rather than environmental attitudes (rokka and uusitalo 2008). move towards understanding ‘actual behaviours within their decision-making contexts’ (lockrey et al. 2018). there are a plenty of strategies designed to implement sustainable development, such as the case of eco-efficiency ‘which establishes the relationship between economy and ecology’ (vasquez et al. 2019) (vasquez et al. 2019). in 1898, a theory of communication called the aida model (attention, interest, desire, and action) was developed based on a study of the life insurance industry that describes the cognitive phases experienced by an individual receiving a new idea or a new product (michaelson and stacks 2011). according to heath and feldwick (2008), the aida (awareness, interest, desire, and action) model contains ‘a four-step formula to get attention, attract interest, create desire, and then take action’ that is the purchase (heath and feldwick 2008). this model is very crucial in assessing the impact of advertising since it is helping to control every step of the psychological transformation up to the purchase made by the individuals (kojima et al. 2010). although the model is very old and has a variety of modifications, the basic principle remains unchanged and is still useful nowadays, so we use it to explain a customer decision process. another widely adopted socio-psychology theoretical model is the theory of planned behaviour (tpb) (ajzen 1991). the tpb suggests that ‘an individual’s behaviour is entirely determined by intention and perceived behavioural control’, and the willing to buy is also defined by perceived behavioural control, individual`s attitude and other subjective norms. customers still need to receive awareness of a product, then show interest in the product according to the benefits of the product, and then show a desire to have these products since they satisfy they demand and decide to purchase (michaelson and stacks 2011). however, echegaray and hansstein (2017) argue ‘there might be a gap between an intention and behaviour since an intention to do something cannot always be translated directly into action’ (echegaray and hansstein 2017). it means that even if a customer is willing to pay (intention or desire), the action itself could require something more. there are also external factors important for society in eco-innovation, besides personal satisfaction. the human development index (hdi) demonstrates that eco-innovation is promoted in countries with environmental problems (sarasini 2009, bitencourt et al. 2020). as methodological research gimenez (2012) recommended to take into account eco-innovation and relationship with ‘eco-demands of all stakeholders’ (gimenez et al. 2012). so, in these countries it is necessary to provide more advantages to raise awareness and it should be a significant part of the research. based on the results of the 20 bm frameworks analysis, biloslavo et.al (2018) proposed a new bm framework termed “value triangle” (vt).(biloslavo et al. 2018). the vt (value triangle) defines ‘co-create value within a business ecosystem that includes society and natural environment’ (stubbs and cocklin 2008). more specifically, the value triangle is showing how company co-creates and co-delivers value with its stakeholders and capture economic value from it (fig. 1). the framework is developed by using richardson (2008) three main components: value proposition, value co-creation and co-delivery system, and the value capture system (richardson 2008). the value proposition includes: public value, customer value, partner value. value created by a company is delivered to different stakeholders. in the value triangle value is received by customers, partners, suppliers, social actors and by the company itself (biloslavo et al. 2018). from biloslavo (2018) analysis is 59 journal of sustainable architecture and civil engineering 2021/1/28 concluded that the knowledge relating to the sustainability and eco-values as such a collaboration, co-creation, are drivers to deliver a sustainability. we also believe the current study gives basis for rethink and change the company’ behaviour forward to the process of developing a eco-system according to the sustainability, but we wish to contribute more in this research in customer value proposition. the innovation is, of course, considered as organizational involving the reorganization of structures, processes, new approaches of management, organizational systems (klewitz and hansen 2014, de oliveira brasil et al. 2016). in order to build green value proposition for customers or society, designers and engineers should propose certain tools for eco-innovation. fig. 1 the value triangle (vt) source: (biloslavo et al. 2018) according to scientists ‘eco-innovation has the capacity to attract green profitability by reducing the environmental impact and creating value for customers and reducing costs’ (andersen 2008, arundel and kemp 2009). so, we expect to build a customer behaviour model which is strongly linked to the eco-innovation concept and creating value for customers while reducing costs by investigation of main drivers that affect customers decision. the customer behaviour model for ecoinnovation products as one of crucial aspects, our model is consideration that environment-related behaviour could be culturally and regionally different (gallego-álvarez and ortas 2017). thus, variation in the level of individualism among countries could influence the eco-innovation results (bitencourt et al. 2020). the difference between country awareness and individual responsibility is possible to overcome through dissemination of knowledge about awareness and eco-efficiency (cucuzzellaa et al. 2020). nonetheless, consumers tend to focus on egoistic product attributes (schuitema and de groot 2015). willingness to pay (wtp) is usually seen as the hicksian consumer surplus measure, and is often defined as the actual price paid (atinkut et al. 2020), so in some countries individual responsibility will prevail over egoistic decision (e.g. price). the studies we examined/overviewed have demonstrated that customers behaviours in energy and water consumption of eco-houses, their awareness, perceptions, according to environmentally friendly products are important (scott and vigar-ellis 2014). customers who respect environment are purchasing the eco-friendly products. awareness of an individual in concerns about the environmental is one of the determinants for environmental friendly behaviours (leszczyńska 2015). koenig-lewis et al. (2014) also supporting environmental friendly behaviour correlation with willing to buy purchase practice and it is affected by social concern, not only rational. (koenig-lewis et al. 2014). so, we put these factors as other non-price factors affecting a customer choice (fig.2). perceived benefits are an important factors of willingness to buy eco-friendly products (kayaman and arasli 2007, kearney 2014). packaging materials, manufacturing technology, and market appeal are necessary criteria (nguyen et al. 2020) to be incorporated into the model. the studies examined also showed that consumers are willing to buy an eco-friendly products as long as the quality is higher than usual products (d’souza et al. 2007), so quality should be considered. van birgelen et al. concluded that ‘consumers are willing to trade off almost all product attributes in favour of environmentally friendly packaging of beverages, except for taste and price.’ (van birgelen et al. 2009). journal of sustainable architecture and civil engineering 2021/1/28 60 young (2008) showed customers of unbranded products are showing less than 10% environmental aspect interest (young 2008), as a result design is one of the significant factors in the model. individual values are also important in defining eco-friendly behaviours (zhang et al. 2018). individual subjective factors such as the degree of awareness, responsibility, environmental values, external factors have important role in affecting eco-friendly behaviours (zhang et al. 2018). fig. 2 the customer behaviour model. choice is affected by cultural differences and individualism. source: developed by the authors based on classical models and the value triangle in order to build a final model of customer behaviour (fig.2) we chose rationalisation we decided to use the classical model with certain eco-benefits (customer values on the left) and perceived consumer costs (scott and vigar-ellis 2014, magnier and crié 2015, lindh, olsson, et al. 2016) on fig. 2. so, the main aspect in our model is price and non-price factors decision. in order to make model simple, we non-price factors price factors building materials functions manufacturing technology market appeal eco-friendly effects (e.g. biodegradable, non-toxic) source: developed by the authors based on classical models and the value triangle grouped all factors into several dimensions: building materials functions (benefits), manufacturing technology benefits (green values), market appeal (design and quality), and factors with eco-friendly effects (e.g. biodegradable, non-toxic, energy saving, and other environmental values the could be important for customers). literature review methods on eco-friendly products and services in this paper we do not focus on factors influencing certain pro-environmental behaviour or price-based behaviour. there is a plenty of research that indicate limited value of sociodemographic characteristics for defining environmentally friendly behaviours of customers (stern et al. 1995). other studies focus only demographics factors (mcdonald and dunbar 2012), these studies showed that the willingness to buy eco-friendly products is highly related to demographics. the results concluded that the age group and marital status have an great impact on willingness to buy eco-friendly products (shahsavar et al. 2020). non/demographic factors that influence eco-friendly behaviours, were grouped as ‘psychographics, knowledge, beliefs, and attitudinal variables’ (laroche et al. 2002, szerényi et al. 2011). later, ‘perceived consumer effectiveness, environmental knowledge, and environmental concern’ were also respected as important variables on eco-friendly behaviours, while environmental concern was the most respected (do paco and raposo 2009, meyer and liebe 2010) followed by perceived consumer effectiveness (albayrak et al. 2011, fisher et al. 2012). some studies also showed that the education level and income level have a positive impact on the eco-friendly behaviour and eco-friendly willingness to buy as well as demographics (chan 2001, junaedi 2012, tran 2014). so, we tried to go through phenomenological approach, and did not put any theoretical findings as hypothesis. but we payed attention to the educational level, age, and other factors as possible correlations. fig. 3 preliminary search results source: developed by the authors using the vosviewer 61 journal of sustainable architecture and civil engineering 2021/1/28 fig. 4 preliminary clusters search results for buildings source: developed by the authors using the vosviewer table 1 elaborated criteria based on the systematic literature review the literature research in order to reveal theoretical findings for the questionnaire was performed from the 1rst of june 2020 till the 20th of june 2020. the first stage of our literature analysis was using keywords in the web of science database: awareness, sustainable development. we found 217 116 papers, which was a rather considerable amount. after adding a new keyword – “eco” we found 19 636. during the introduction phase with the most relevant papers, new keywords were found: ecological awareness, eco-innovation, willingness to pay, and eco-feedback. after the preliminary search, we started to narrow the search and used the following search formula according to our research goals: ( eco-innovation ) or ( eco-house or eco-building ) and ( ecological and awareness ) with 674 papers. after using the content analysis platform, we found 6976 links and 6 clusters with 271 items (fig. 3) in the vosviewer software (web of science database). in order to build a framework, we chose most relevant links (fig.4) in the vosviewer results. as it could be seen, the most relevant clusters include several common links as keywords. after selecting most relevant papers based on results (40 papers in the web of science) we synthesised the following criteria and used dimensions (groups) created throughthe concept analysis (fig.2) table 1 shows the elaborated criteria based on our literature review (for full list of factors see appendix 1). authors dimensions/groups price building material functions/ functionality manufacturing technology market appeal/design/ appearance eco-friendly effects/ environmental impacts (nguyen et al. 2020) yes functionality new and advanced technology for production visually attractive graphic design biodegradable, non-toxic, easily decomposed, reusable recyclable, paperbased, natural and organic sources of materials used in production, (scott and vigar-ellis 2014) yes no data eco-friendly manufacturing process. no data recyclability and reusability (young 2010) yes no data no data no data mostly recycling (lindh, williams, et al. 2016) yes no data no data design reusable (magnier and crié 2015) yes yes, enlargement no data design, shape, size biodegradability, recyclability and reusability. (lewis and stanley 2012) no data no data no data no data biodegradability, recyclability and reusability. journal of sustainable architecture and civil engineering 2021/1/28 62 authors dimensions/groups price building material functions/ functionality manufacturing technology market appeal/design/ appearance eco-friendly effects/ environmental impacts (bertolini et al. 2016, herbes et al. 2018) life cycle assessment (palombini et al. 2017, boesen et al. 2019) eco-friendly raw materials (mueller et al. 2010, reimann et al. 2010, gwozdz et al. 2015, tait et al. 2016, wagner et al. 2019) design subfactors: s1 minimal/ minimalistic reduced,timeless silhouettes s2 durable – robust, high-quality fabrics s3 multifunctional – functional (e.g., reversible) garment s4 dynamic – good fit/size (e.g., adjustable for mobility or growth) s5 unique – uncommon style s6 decorated xcreative/ (wagner et al. 2019) (verghese and lewis 2007) functionality (martinho et al. 2015) mostly price quality, functionality design sustainability (chalal et al. 2020) energy consumption heating system, energy ratings, energy usage in kwh energy savings, efficiency control e.g. through smartphone (atinkut et al. 2020) social responsibility of respondent (cognitiveness): knowledge of eco-efficiency, perception and attitude of environment (positive/neutral), conscience (concerned, not concerned), eco-experience. wtp factors: gender, age, education, family size, source of income 63 journal of sustainable architecture and civil engineering 2021/1/28 the empirical research based on theoretical findings was performed from the 5th of july 2020 till the 20th of july 2020. expert interviews and focus groups for data validation were conducted from the 5th of july 2020 till the 20th of july 2020. the authors’ scheme of research design could be seen on fig. 5. multiple techniques were used to improve the construct validity and reliability and improve scientist’ judgments and data truthfulness. in order to validate the survey instrument in the same type of atmosphere and execution in which it was designed to be used, a pilot test conducted on small respondent population was run. during 2 weeks, interviews among company executives and academic staff were carried out. all respondents agreed to evaluate the survey questions. the analysis of the independent variables in the pilot test suggested that 7% of questions needed some further clarification (see table 2). prior to moving forward with the actual research, these questions were re-written and given during the interviews for cross-checking and clarity review. prior to obtaining the final results, the authors used the modified questionnaire, for the survey questions. the authors modified the original method with statistical evidence. based on provided feedback during the interviews, the authors stated that the pilot survey showed a deep consideration about the green-style. this situation was recognised by the authors as a sign of good awareness about the green-style. authors dimensions/groups price building material functions/ functionality manufacturing technology market appeal/design/ appearance eco-friendly effects/ environmental impacts (gill et al. 2010, 2011, ridley et al. 2013, elsharkawy and rutherford 2015, pretlove and kade 2016) smart heat control (overheating), water and energy use. pv availability. the passive house planning package (maruejols et al. 2013) green efficiency (huebner et al. 2013, jones et al. 2015) thermal comfort (zeng et al. 2018) yes window blinds, retrofit fabrics, more efficient equipment, indoor air quality (ventilation), smart temperature, acoustic, reliability (guarantees), use of land visual, aesthetic, decoration discussion and validation of the elaborated criteria: the case of latvia source: developed by the authors journal of sustainable architecture and civil engineering 2021/1/28 64 the expert survey and reference groups are the second most important research phase. with the help of the experts representing a building industry, the authors identified the significance coefficients of the factors influencing customers’ behaviour. the objective of the interviews was to explore the factor evaluation practices in the building industry in latvia, so that this information could be used to develop a questionnaire for the quantitative study. on the basis of the information provided by the experts and recommendations regarding enterprises, a list of corrections was suggested. the expert reference group (5 experts) discussion allowed to improve validity of the research. during the interviews and expert focus groups, the authors repeated or clarified questions that may have been unclear to the respondents. the recording device was used during interviews, but the authors entered those interviews results manually as text conclusions into standard word processing documents. the purpose of the questions was to determine experiences, perceptions, and the ideas of executives and non-executives about the process of selecting and assessing certain eco-house benefits. the authors chose triangulation to ensure validity and reliability of the research (data validation through expert focus groups, expert interviews, and feedback from pilot groups. fig. 5 the scheme of the research design 5. pilot survey (random respondents) 6. survey revision through interview (manufacturing branch, experts and academic stuff) data validation 1. categories and factors developed through literature review. 3. categories obtained through academic focus group discussion (academics, discussion). 2. categories developed through experts’ focus group (exploratory, industry experts). source: developed by the authors table 2 questions needed to be modified based on the pilot survey description of original questions 1h. long life cycle and cost management (repair) (20% of misinterpretation) 1k. passive house benefits. (40% of misinterpretation) 4e. eco-efficient production processes and raw materials in connection with the use of natural resources (eco-efficiency) (15% of misinterpretation) 4f. corporate social responsibility through participation in associations and government environmental programs (30% of misinterpretation) the authors developed evaluation based on interviews, with evaluation from five-point likert scale (1 – not important, 5 – strong) source: developed by the authors 65 journal of sustainable architecture and civil engineering 2021/1/28 after the discussion with the experts, new questions were added: 2d. total quality management production. production certificates; 2e. synchronization and continuity of the production process. smart factory, robotization, high production quality and 4f. corporate social responsibility through participation in associations and government programs that protect nature. interpreting the pilot results after considering the survey results, the questionnaire was used in the ilot survey. the simple analysis for 15 respondents was presented, the elaboration of eco-innovation marketing strategies was based on the previously created model (fig. 6 based on fig. 5. steps 1–5). as a result of implementing a new concept of eco-innovation value, now it is possible to assess the impact on different change elements. fig. 6 (visualization) shows the most important factor contribution. fig. 6 most valued factors (5 – very important) in % of total respondents 0% 10% 20% 30% 40% 50% 60% 70% 80% lowest price with conventional non-toxic materials the average price of an eco-house with eco-friendly materials that also provide energy efficiency very expensive smart eco-houses made from environmentally friendly materials, which also provide maximum energy efficiency and excellent design ecohouse with raw materials not toxic to the environment(non-toxic) eco-houses with raw materials that are environmentally efficient in terms of the use of environmental resources (eco-efficiency) source: the pilot survey table 3 please prioritize answers from 1 to 5 source: the pilot survey priority points good price 1 22 good design 2 21 very high energy efficiency of materials, components and systems, which can significantly reduce costs 3 18 eco raw materials 4 18 smart home options that allow you to automatically remotely control the consumption of resources (heat, electricity, water, etc.) 5 15 environmentally friendly manufacturing technology 6 11 based on the new results, we could evaluate the priority of basic elements (table 3) according to respondents’ subjective values. lastly, the most valued elements (at least 50% of respondents) are represented in table 4. journal of sustainable architecture and civil engineering 2021/1/28 66 conclusions the present paper has provided a detailed framework for prioritization of factors based on the literature research with an empirical example for the specific latvian situation. first, the authors have observed the eco-friendly/green life style methodology and created the questionnaire design (fig. 2). second, the important conclusion associated with the assessment of factors and corrections has been made, and a validated list of factors has been presented (appendix 1). third, a new assessment concept has been drawn/elaborated and a short analysis of possible strategies has been proposed, which is convenient for eco-innovation companies. in latvia, eco-houses with environment friendly materials yet not expensive (price over design decision) are more popular than luxury and stylish ones with a high price. fast response of strategies to rapidly changing market conditions becomes the most demanded topic for eco-house developers. within the framework of the present research, an integrated framework has been proposed for the wood manufacturing company using the approach augmented with the presented methodology to obtain criteria weights and prioritize alternative elements, which could be used even for eco-innovative companies. finally, according to the empirical results, we interpreted results for a better understanding of the certain factor (value) effect on customer behaviour. the proposed approach shows correlation of the existing elements with awareness of pilot study respondents. majority of the respondents consider green environment (80%). at the same time, they are not willing to pay premium for fully green houses, showing cost orientation. customers expect “very high energy efficiency of materials, components and systems, which can significantly reduce costs” which is the 3rd important value. but still – design is very important for customers, especially concerning reliability and repair (75% and 70% accordingly). the limitations of the research can be discussed since latvia has a specific geo-political and economic position (global innovation index 44 out of 127 and, compared to other eu countries, latvian r&d expenditure is greatly reduced – 0.4% of the gdp in 2016 (eu, 2018; wipo, 2017). future research in the baltic states could concompany or reject this limitation for greater population. latvia is a good case for analysis since it has open market with perfect logistic value chains and works as a bridge between eastern and western europe. for this reason, the research results are crucial for wood manufacturing companies in small countries with the target of becoming both locally and internationally competitive in the european markets. as for practical implication of the research case, it allows eco-innovative companies to assess their strategic posture with the presented method and follow the discussed strategic gaps both for the domestic and international markets. in the future research we will provide a mathematical model based on the factor analysis using spss, which will be the example of using our tool for wood manufacturing companies. question description % of respondents 1a. raw materials and components provide good air circulation (ventilation), thus good air quality 60% 1g. high energy efficiency of materials, heating units and systems (for example, windows, heat resistance of walls, energy efficiency of the heating system) 80% 3b. reliable, durable design, high-quality fabrics 75% 3d dynamic design (easy to repair, complemented, suitable for various styles); good fit / size (e.g., adjustable for mobility or growth) 70% 3e. unique, unusual uncommon style 60% 4c. raw materials not toxic to the environment 85% 4g. the use of natural raw materials in the product and production. 60% source: the pilot survey table 4 result interpretation for transformational factors 67 journal of sustainable architecture and civil engineering 2021/1/28 references summarizing the results, it can be concluded that preliminary results show respondents’ practicality towards green life-style. “eco building with raw materials that are friendly to the environment are more important” in comparison to “expensive smart 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position at the organization: prof., dr.oec. riga technical university, faculty of engineering economics and management, faculty of engineering economics and management, riga, latvia main research area risk management, operations research, expert evaluations, statistics, factor analysis and correlations, insurance, financial management address, 6 kalnciema street, room 316, riga, lv-1048` e-mail: irina.voronova@rtu.lv diāna bajare position at the organization: prof., dr.sc.ing. institute of materials and structures, department of building materials and products, riga, latvia main research area recycling and energy efficiency, innovative building materials, eco-houses, eco-innovation address, 6b kipsalas street, riga, lv-1048, latvia ` e-mail: diana.bajare@rtu.lv 65 journal of sustainable architecture and civil engineering 2022/1/30 the growth of cities often disordered brings several mobility challenges, both in guaranteeing public transport and creating pedestrian-friendly urban spaces. this paper aims to identify the walkability drivers in urban areas and investigate walkability behavior. the survey was carried out in southern brazil, with a sample of 439 respondents. data were subject to factorial analysis, regression analysis, and variance analysis. the analysis revealed four walkability drivers that explain pedestrian behavior: (i) infrastructure, (ii) traffic conditions and behavior, (iii) built and natural environments, and (iv) social relations. the results show that built and natural environments and social relations were the most significant aspects in explaining walkability’s overall perception. concerning socio-demographic aspects, the study points out that (i) men feel safer than women when walking in the neighborhood; (ii) the presence of trees and attractive places along the street increases the walking behavior of nonsedentary people; and (iii) the perception of the neighborhood’s beauty increases with age. the research provides contributions regarding understanding the interrelated aspects of walkability behavior. finally, the study offers relevant evidence for social researchers and urban planners by identifying walkability drivers and supporting political and academic debate elements. keywords: sustainable city, pedestrian behavior, walkability, survey, brazil. walkability drivers for sustainable cities: a pedestrian behavior survey received 2021/09/06 accepted after revision 2022/02/04 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 65-77 doi 10.5755/j01.sace.30.1.29756 walkability drivers for sustainable cities: a pedestrian behavior survey jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.29756 jennifer domeneghini federal university of rio grande do sul (ufrgs) janaina macke university of caxias do sul (ucs) joão alberto rubim sarate* federal university of rio grande do sul (ufrgs) introduction urbanization occurs at an unprecedented rate, with the projection that three-quarters of the world’s population will live in urban environments by 2050 (bibri & krogstie, 2017). this estimate indicates that cities play critical roles in providing urban environmental quality to the population at a minimum acceptable standard and climate change challenges (bibri & krogstie, 2017; iwan & poon, 2018). the shape of contemporary cities has been seen as a source of environmental resources and social problems, such as the consumption of around 70% of the world’s resources, being large consumers of energy and contributors to the emissions of gases that cause the greenhouse effect (bibri & krogstie, 2017). the challenges related to cities are due to population density and the intensity of economic and social activities related to the inefficiency of environmental resources (bibri & krogstie, 2017) and other factors such as inadequate urban projects, social deprivation, mobility, and ineffective accessibility, increased need for transport, public safety, decreasing health, traffic congestion, among others (bibri & krogstie, 2017). abstract *corresponding author: jasarate@gmail.com journal of sustainable architecture and civil engineering 2022/1/30 66 the idea of making cities more sustainable has grown in importance in several fields of knowledge, such as urban planning, environment, and public policy management (cerutti et al., 2019; jayakody et al., 2018). among the dimensions of a sustainable city, walkability has been identified as one of the central axes of quality of life in sustainable cities (jayakody et al., 2018). walkability is one of the strategic elements that are part of urban mobility in general and is characterized both by the study of the physical means that provide walking and by the qualitative aspects about what motivates people to walk in the urban space (ewing et al., 2006; jayakody et al., 2018). in addition to these two approaches, the nature of walking can be motivated by physical activity or as an active means of transportation (livi & clifton, 2004). regardless of the motivation, improving the walkability of a city has a direct impact in several fields, such as recreation studies (haq, 2011; frank et al., 2010), urban design (su et al., 2017; cerin et al., 2006), public health, transportation planning (leslie et al., 2005; cerin et al., 2006; lo, 2009), and quality of life (macke et al., 2018; lee, 2008; litman, 2003). for this reason, researchers and public managers are increasingly interested in understanding pedestrians’ behavior, perceptions, and attitudes and the relationship of this perception with the physical environment (livi & clifton, 2004; zuniga-teran et al., 2017). many researchers have analyzed urban transformations and the impact on walkability (su et al., 2019; habibian & hosseinzadeh, 2018; riggs, 2017), but more work needs to be done on studies that include both objective and subjective data to analyze the individual behavior of pedestrians according to the morphology of the spaces. the tools used to verify walkability have generally been poorly adapted to capture the characteristics of the built environment and attitudes and behaviors about walking, and since they were not originally designed to access pedestrians’ perception of these issues (livi & clifton, 2004). the tools that assess walkability fail to access different types of walking behavior, and they do not link pedestrian behavior with the definition of a sustainable city (su et al., 2017). a sustainable city requires improvements in quality and safe access to active mobility, which demands knowledge and understanding of the pedestrians’ perception of their walking behaviors and the walkability drivers. according to socio-demographic features, these gaps and the debate about walkability in sustainable cities lead to this paper’s primary objective: to identify the walkability drivers in urban areas and investigate the perception of walkability. the survey was carried out in southern brazil, in which the attitudes and behaviors about walking of 439 respondents were investigated. this paper is organized as follows. after this introduction, the theoretical background of walkability is presented. the third section describes the methodological steps, procedures, and criteria. the fourth section presents and discusses the study results. finally, the conclusion section highlights the study’s theoretical and applied contributions. walkability urban planning is gradually changing, with goals to modify pedestrian streets’ landscapes that favor walking and improve urban sustainability (su et al., 2019; habibian & hosseinzadeh, 2018; riggs, 2017). most research still focuses only on one type of walking: physical activity or walking as a mode of transport, aiming to learn more about one type or another. these surveys’ common point focuses on pedestrians’ perception (livi & clifton, 2004). in recent years, there has been an increase in popularity and accessibility indexes, creating measures that assess both the built form and residents’ needs. accessibility, or just access, refers to the ability to achieve the desired goods, services, and activities, and walking provides essential mobility; that is, many people depend on walking to access activities, such as medical services, education, and work (litman, 2003; ewing et al., 2006; lo, 2009). accessibility can be assessed using surveys with residents, field surveys, and geographic information systems to determine the portion of essential destinations that can be conveniently reached through travel on foot, in par67 journal of sustainable architecture and civil engineering 2022/1/30 ticular by disadvantaged populations (litman, 2003), which is vital in considering the assessment of the walkability of cities. walkability offers various benefits, including accessibility, cost savings for the consumer and public economy, more efficient land use, habitability, public health, and economic development (litman, 2003; manaugh & el-geneidy, 2011). pedestrians can walk for several purposes: access a destination as a means of transport, exercise, leisure, or some combination (livi & clifton, 2004). however, the walking behavior’s complexity extends beyond the physical, social, and psychological and motivations, perception of security, ability to move around, personal attributes, income so essential to the decision to walk (livi & clifton, 2004). there are several elements and variables to be considered regarding the walk. as the physical characteristics, qualities of urban design, and individual reactions determine the capacity of the general passage of a street, what we mean by the way people feel about the street as a place to walk (litman, 2003; leslie et al., 2005; ewing et al., 2006; owen et al., 2007). the main elements of local mobility are proximity and connectivity, with proximity being related to mixed land uses that create shorter distances between homes and destinations such as shops or work, and connectivity is the variety of routes to the destination (owen et al., 2007; lo, 2009; frank et al., 2010; habibian & hosseinzadeh, 2018). in several studies analyzed by lo (2009), many measures overlap when it comes to the analysis of pedestrians’ walking capacity, such as maintenance of sidewalks and continuity, connectivity between streets, safety in crossings, absence of heavy traffic and high speed, traffic protection, the density of land use, diversity of land use, presence of vegetation, visual interest and perception of security. different studies show that it is necessary to consider several drivers for walking, mobility, and pedestrians to enable the subsequent measurement of these items (litman, 2003; leslie et al., 2005; lo, 2009). however, physical resources individually may not tell us much about the experience of walking down a specific street, as they do not capture people’s general perceptions of the environment on the streets, perceptions that can have problematic or subtle relationships with physical characteristics (leslie et al., 2005; ewing & handy, 2009; manaugh & el-geneidy,2011). perception can result from interactions between past experiences, culture, and interpretation of the perceived drivers such as physical characteristics, urban design qualities, and individual characteristics that can influence how an individual feels about the environment as a place to walk (ewing & handy, 2009). thus, it is considered that the attributes of the built environment can be measured both objectively (for example, using data from geographic information systems) and subjectively (for example, using questionnaires (leslie et al., 2005; cerin et al., 2006; owen et al., 2007). a tool that has been used for walkability analysis is the walk score, which has been recognized as valid and reliable for estimating access to nearby facilities a critical component of the physical activity environment. however, there is still no determination whether this tool relates to other components such as connectivity on the streets, access to public transport, residential density, and crime. even so, these factors can be measured in gis and correlated to walk scores, which offer quick and easy-to-use support for considering neighborhood density and close accesses (carret al., 2010; su et al., 2017). another study was carried out in neighborhoods in maryland, where three neighborhoods were assessed. the instrument was designed to make an initial assessment of pedestrian behaviors, including those related to transportation and physical activity, attitudes about walking, perceptions about the built environment, and some demographic information (livi & clifton, 2004). this instrument was based on the partnership for a walkable america (pwa), which consists of perception issues addressing sidewalks, pedestrian crossings, safety, and fun. this was the model considered for elaborating the questionnaire applied in the study, as it offers considerations of different elements and consideration of people’s perceptions. journal of sustainable architecture and civil engineering 2022/1/30 68 the study by adkins and colleagues (2017) analyzed 17 research on the environment versus mobility issue showed that the environment has more effects on walking and physical activity for disadvantaged people than favored groups and that disadvantaged populations face more walking problems tranquility, safety, and health. the research by moura and colleagues (2017) considered different pedestrian groups (adults, children, the elderly, pedestrians with reduced mobility) and travel purposes (utilitarian and leisure), considering different factors. the results showed that different groups of pedestrians and reasons for travel significantly impact the assessment of walking ability (moura et al., 2017), so the importance of considering these variables when assessing walkability (moura et al., 2017; aghaabbasi et al., 2018). emerging evidence supports a link between the built environment in the neighborhood and physical activity, showing that improving the built environment to facilitate and increase physical activity is related to people’s health (livi & clifton, 2004; frank et al., 2010). therefore, walkability is increasingly gaining attention as a critical issue in promoting healthy, environmentally friendly, and socially active practices, as it provides social, environmental, and economic benefits. besides, in many cases, the only way for people to access daily activities is on foot. besides, walkability brings life to the streets and makes them habitable, contributing to safer environments (moura et al., 2017; habibian & hosseinzadeh, 2018). these elements make the study of walkability critical in the ever-increasing search for sustainable cities and prioritizing active mobility, such as walking. method questionnaire design the questionnaire was adapted from livi & clifton (2004), in which walkability is defined “upon the ease of street crossings, sidewalk continuity, local street network characteristics, and topography” (livi & clifton, 2004, p. 4). the variable referring to “during the winter, sidewalks are kept clear of snow” was changed for the perception of walkability, considering this weather phenomenon is not common in the region studied. a likert scale of 5 points (1 = strongly disagree; 5 = strongly agree) was used for the variables for assessing walkability. the original questionnaire, published in english, was translated into portuguese, and two translators performed a content validity test. three researchers from the social theory research group carried out the questionnaire layout adjustments and slight adjustments of the portuguese language in face-to-face meetings. the pilot test was carried out on ten respondents before the sample was applied, and small semantic adjustments were made to facilitate the respondents’ understanding. the questionnaire was constructed subdivided into two parts: the first part was composed of 31 closed questions on the assessment of walkability; the second contained 11 variables on socio-demographic data (gender, age, the primary mode of transport, possession of a driving license, owns a dog, owns a car, has children under 5, neighborhood and city). survey procedures data were collected between june and august 2019 by volunteer university students who regularly participate in the research group’s activities. the questionnaires were printed, and people were interviewed in public and open places, in squares and parks. the field researchers went through previous training. the 439 respondents interviewed were informed about their voluntary participation, the anonymity of the answers, and the use of the answers only for academic purposes. the average response time of 15 minutes was sufficient to answer the questionnaire. data analysis the answers were initially prepared in an electronic spreadsheet, and, later, they were organized in the spss software (statistical package for the social sciences), version 20 for windows® for data analysis. 69 journal of sustainable architecture and civil engineering 2022/1/30 the data were analyzed using descriptive statistics, factor analysis, linear regression, and analysis of variance. descriptive statistics were used for the socio-demographic characterization of the sample. factor analysis is used to summarize and reduce data (hair et al., 2003), and it was used to identify the walkability drivers. linear regression was used to identify the relative weight of the variables (hair et al., 2003) in the general perception of walkability. finally, analysis of variance was used to identify significant differences in mean (hair et al., 2003) between perceptions according to the respondent’s socio-demographic profile. results: analysis and discussion the context: passo fundo region in south brazil the survey was conducted in the passo fundo region, located in the rio grande do sul (the southernmost state in brazil). the city of passo fundo is the principal city in the region (29.61% of respondents). the city has an estimated population of 203,275 people in 2019 and a municipal human development index (mhdi) of 0.776, according to the ibge (2019). cities are considered small and medium-sized, and mhdis levels are between medium and high (ibge, 2019). all cities are based mainly on agriculture (especially the small cities). passo fundo is the largest city. it is also considered a hub in commerce, industry, education, and health, a nationally recognized medical hub (the city has nine hospitals), and a national capital of culture (having nine higher education institutions). identification and analysis of walkability drivers descriptive analysis revealed the sample’s main characteristics concerning the family: 61.3% are women; 49.5% of respondents are up to 36 years of age (sample mean: 37 years); 17.8% have children under five years old; 57.2% have a dog. regarding means of transportation: 74.2% have a car; 75.9% have a driver’s license; 65.9% have the car as the primary means of transportation, while only 16.9% have walking as the primary means of transportation. regarding walking habits, sedentary behavior was defined as less than 20 minutes a day; they represent 54.8% of the sample. of the total sample (n = 439), 12.1% walk more than 3 km per day. the primary trips are close to home (33.11%) and close to school or work (28.17%). for 44.1% of respondents, the seasons do not interfere with the habit of walking. besides, 66.0% usually walk alone, and 38.7% usually walk at night. 55.6% say it is possible to go to work or school on foot, but only 34.62% usually do so. considering the main reasons for walking: 55.8% walk because it is an opportunity to do physical activity and 18.9% walk for practicality, indicating that urban design favors walkability for this portion of the sample. regarding the main reasons that hinder or limit the habit of walking: 54.67% of respondents point out the lack of time as a limiting issue for walking, and 14.58% point out the lack of security as a limiting factor for the practice of walking. when asked what factors would make them walk more: 36.88% would walk more if there were good sidewalks, 31.21% would walk more if there were more and better public lighting on the roads, and 24.15% would walk more if there were more parks and squares. this research aims to go beyond the walkability assessment made by livi & clifton (2004). the data were subjected to factor analysis using pca (principal component analysis) through the varimax rotation. missing cases were excluded by listwise treatment (this option means that any case that failed to answer a question is disregarded in the analysis). the index of kaiser-meyer-olkin (kmo) adequacy of the sample was 0.726, and bartlett’s test of sphericity (significant to 0.000) indicated the factorability of data (hair et al., 2003). the factorial analysis’s final model is formed by 12 variables, indicating that six were left out of the model. these variables were removed, one by one, using commonality as a criterion. in addition to the variables provided for in the study by livi & clifton (2004), a variable for the general assessjournal of sustainable architecture and civil engineering 2022/1/30 70 ment of walkability was added, used as a dependent variable in the linear regression analysis: walk “generally speaking, it is easy to walk in my neighborhood”. the total explained variance of the model was 61,768%, with the “infrastructure” driver explaining 17,571%; the “traffic conditions and behavior” explaining 16,287%; the “built and natural environments” explaining 15,233% and, finally, the “social relations” driver explaining 12,678%. the analysis results converged in 5 iterations, and the cronbach’s alpha for the scale was 0.762, which indicates a satisfactory result for an exploratory study (hair et al., 2003). table 1 factorial results for walkability driver items loading mean standard deviation infrastructure (0.761)* inf1–sidewalks are safe and clear of litter, leaves, poles, and other obstacles. 0.839 2.46 1.114 inf2 sidewalks are safe for people with mobility disabilities. 0.785 2.12 1.024 inf3–there are enough sidewalks 0.731 2.80 1.214 traffic conditions and behavior (0.651)* tcb1 -drivers drive at a safe speed. 0.700 2.75 0.999 tcb2–drivers usually respect pedestrians. 0.691 2.74 1.059 tcb3–there are sufficient traffic signals and wellmarked crosswalks. 0.676 2.78 1.178 tcb4–traffic signals allow enough time to cross the street. 0.638 3.16 1.103 built and natural environments (0.666)* bne1–there are trees and attractive places along the street. 0.853 3.39 1.086 bne2–there are benches and places to sit. 0.693 3.15 1.217 bne3–my neighborhood is attractive and enjoyable to walk in. 0.626 3.52 1.027 social relations (0.604)* sor1–there are commercial areas within walking distance of my residence. 0.818 3.36 1.307 sor2–i often see people walking and cycling in my neighborhood. 0.767 3.51 1.109 * cronbach’s alpha the infrastructure driver (m = 2.458; sd = 1.117) includes the variables: (i) “sidewalks are safe and clear of litter, leaves, poles and other obstacles”; (ii) “sidewalks are safe for people with mobility disabilities”; and (iii) “there are enough sidewalks”. this dimension was the one that presented the lowest averages, which suggests that respondents are not satisfied with sidewalks’ infrastructure. in the study by moura et al. (2017), similar results were found. pedestrians, representing the elderly and with reduced mobility, were affected by the sidewalk’s sufficient width, which does not accommodate this type of population becomes an inconvenience when walking. the study results by aghaabbasi and colleagues (2018) show that sidewalks are an essential driver in bringing safety, especially for people with reduced mobility. moreover, jayakody et al. (2018) found that sidewalks must be free of obstacles and leveled to access people with reduced mobility. another component pointed out that favored infrastructure environments are more walkable (such as places with adequate sidewalks) than disadvantaged environments (frank et al., 2005; adkins et al., 2017 & lo, 2009), which proves that infrastructure is one of the points to consider making the place more walkable. 71 journal of sustainable architecture and civil engineering 2022/1/30 the traffic conditions and behavior driver (m = 2,846; sd = 1,088) embraces the variables: (i) “drivers drive at safe speed”; (ii) “drivers usually respect pedestrians”; (iii) “there are sufficient traffic signals and well-marked crosswalks”; and (iv) “traffic signals allow enough time to cross the street”. the averages of three variables are less than three, which indicates that respondents assess that traffic conditions are considered flawed and that drivers do not drive safely, respecting pedestrians. in this line, providing traffic safety is one aspect that needs to be improved, as it is related to the adoption of walking as transportation (cerin et al., 2006). cities should consider infrastructure items such as safety and lighting lanes in the traffic safety infrastructure (cerutti et al., 2019). less walkable areas have larger blocks, fewer intersections, and greater distance at intersections (leslie et al., 2005; lo, 2009), making it difficult to cross the roads. the built and natural environments driver (m = 3.356; sd = 1.110) comprises the variables: (i) “there are trees and attractive places along the street”; (ii) “there are benches and places to sit”; and (iii) “my neighborhood is attractive and enjoyable to walk in”. respondents’ assessment of this driver was better than that of previous drivers. the presence of resting places, such as seats, is attractive to people, but these are sometimes not used due to a “sense of protection”. still, they are essential to encourage walkability (jayakody et al., 2018). another point is that green spaces contribute to people’s quality of life, promoting several benefits, such as reducing urban heat, improving air quality, valuing property, and, mainly, psychological benefits, by providing relaxation and recreation (frank et al., 2005; haq, 2011; lo, 2009). just as respondents noted trees’ presence on the streets they walk on, land-use planners must recognize the need to walk spatially the same and the health benefits provided in built environments. typical approaches to improving street landscapes include providing green belts and sidewalks, building benches and shelters, balancing streets with pedestrian widths, and installing pedestrian crossings (cerutti et al., 2019; su et al., 2017). the social relations driver (m = 3,438; sd = 1,213) encompasses the variables: (i) “there are commercial areas within walking distance of my residence”; and (ii) “i often see people walking and cycling in my neighborhood”. this dimension was the one that presented the highest averages, which suggests that respondents are satisfied with social relations as an element for walkability perception. in the study by lee (2008), it was found that individuals care more about perceptual perspectives than with environmental perspectives, which goes against what was found in the result above, showing the high degree of relationship in social aspects and not in physical aspects as infrastructure. regarding the infrastructure of the neighborhood, moura et al. (2017) point out that the lack of immediate commerce impacts the convenience of walking to reach these places due to factors such as the concentration of commerce in a few streets and with a predominance of homes and services, that is, the diversity of use of the neighborhood is low, which prevents people from choosing to walk (frank et al., 2005; leslie et al., 2005; ewing et al., 2006; owen, 2007; jayakody et al., 2018). places with active façades, which have shops on the ground floor, are pleasant for pedestrians who travel these places and have a more significant population when they can be reached on foot. the ability to walk dramatically impacts the community’s habitability, the streets being an important aspect when they provide places where people interact with their community (litman, 2003). the social factor is an essential component for people to walk, and, for this reason, the increase in the mix of land use should be a practical approach for the construction of coexistence streets (su et al., 2017; su et al., 2019). in short, as our cities face pressure to run out of cars, the challenge is not merely to create “walkability” but to create great walkable streets that encourage activity, observation and experience, beauty, and visual interest (riggs, 2017). therefore, the improved walkability increases accessibility, community livability, improves public health and supports strategic economic development, land use, and equity (litman, 2003; su et al., 2019). the relationship between walkability variables and general perception “in general, walking in my neighborhood is easy” was tested by linear regression using the stepwise method (table 2). the asjournal of sustainable architecture and civil engineering 2022/1/30 72 table 2 linear regression model model r r square adjusted r square st. error of the estimate durbin-watson 1 0.454a 0.206 0.204 0.896 2 0.566b 0.321 0.317 0.830 3 0.592c 0.351 0.346 0.812 4 0.606d 0.367 0.361 0.803 5 0.613e 0.375 0.368 0.799 6 0,618f 0.382 0.372 0.796 1.854 sumptions of homoscedasticity, multicollinearity and normal distribution of errors were achieved for linear regression analysis. the regression results show that six variables in the model are significant for walkability and represent 37.2% (r2 = 0.372, p <0.05) of the general perception of the walkability: bne3 my neighborhood is attractive and pleasant to walk, sor2 i often see people walking and cycling in my neighborhood, inf3 there are enough sidewalks, tcb2 drivers tend to respect pedestrians, inf2 sidewalks are safe for people with motor disabilities, bne1 there are trees and places attractive to along the street. the results show that among the model variables, two belong to the walkability driver “built and natural environments”, two variables belong to the driver “infrastructure”, one variable belongs to the driver “social relations”, and one to the “traffic conditions and behavior”. the durbin-watson test was used to detect the presence of autocorrelation (dependence) in the residuals of a regression analysis (hair et al., 2003). the model’s test value (1.854) indicates that we can state that the waste is independent with a 95% confidence level. in other words, the perception of walkability depends significantly on the performance of these variables (table 3). the perception of walkability can be written as follows: walk = 0.259 *bne3 + 0.319 * sor2 + 0.104*inf3 + 0.118* tcb2 + 0.094* inf2+ 0.090* bne1 (1) the variable with the most significant weight in the general perception of walkability is “sor2 i often see people walking and cycling in my neighborhood” (beta = 0.319; sig. 0.0000). one of the explanations for the presence of pedestrians and cyclists is that for physical activity, no urban element is more important than the streets, as these are where active trips to work, shop, get involved in other daily activities take place (ewing et al. 2006). the bicycle also appears on the a. predictors: (constant), bne3 – my neighborhood is attractive and enjoyable to walk in. b. predictors: (constant), bne3 – my neighborhood is attractive and enjoyable to walk in, sor2 – i often see people walking and cycling in my neighborhood c. predictors: (constant), bne3 – my neighborhood is attractive and enjoyable to walk in, sor2 – i often see people walking and cycling in my neighborhood, inf3 – there are enough sidewalks d. predictors: (constant), bne3 – my neighborhood is attractive and enjoyable to walk in, sor2 – i often see people walking and cycling in my neighborhood, inf3 – there are enough sidewalks, tcb2 – drivers usually respect pedestrians e. predictors: (constant), bne3 – my neighborhood is attractive and enjoyable to walk in, sor2 – i often see people walking and cycling in my neighborhood, inf3 – there are enough sidewalks, tcb2 – drivers usually respect pedestrians, inf2 sidewalks are safe for people with mobility disabilities f. predictors: (constant), bne3 – my neighborhood is attractive and enjoyable to walk in, sor2 – i often see people walking and cycling in my neighborhood, inf3 – there are enough sidewalks, tcb2 – drivers usually respect pedestrians, inf2 sidewalks are safe for people with mobility disabilities, bne1 – there are trees and attractive places along the street. g. dependent variable: walk generally speaking, it is easy to walk in my neighborhood. 73 journal of sustainable architecture and civil engineering 2022/1/30 table 3 linear regression coefficients final model unstandardized standardized t sig. b std. error beta (constant) 0.801 0.193 4.155 0.000 bne3 – my neighborhood is attractive and enjoyable to walk in 0.253 0.045 0.259 5.639 0.000 sor2 – i often see people walking and cycling in my neighborhood 0.288 0.038 0.319 7.641 0.000 inf3 – there are enough sidewalks 0.086 0.037 0.104 2.351 0.019 tcb2 – drivers usually respect pedestrians 0.112 0.040 0.118 2.762 0.006 inf2 sidewalks are safe for people with mobility disabilities 0.093 0.044 0.094 2.114 0.035 bne1 – there are trees and attractive places along the street. 0.084 0.042 0.090 1.994 0.047 streets as a healthy and sustainable means of transport and physical activity (kellstedt et al., 2020). when these streets provide the right places (such as sidewalks, bike lanes), there is an incentive for more people to be present on the streets (zuniga-teran et al., 2017). the second variable with the most significant evaluation is “bne3 my neighborhood is attractive and enjoyable to walk in” (beta = 0.259; sig. 0.0000). the neighborhood configuration can influence the decision to walk, indicating that the neighborhood’s physical structure is one of the key elements to explain walking patterns (larrañaga et al., 2009; nieuwenhuijsen, 2020). another reason cited by leslie et al. (2005) was that, in neighborhoods with high walking rates, residents reported that attributes related to residential density, the combination of land use (access and diversity), and the connectivity of the streets have higher values than residents who live in neighborhoods with low circulation. these issues are related to living together since walking becomes a pleasant activity in terms of interaction with people, the natural and built environment, and other pedestrians (moura et al., 2017). the other variables there are enough sidewalks, drivers usually respect pedestrians, sidewalks are safe for people with mobility disabilities, and the presence of trees and attractive places along the street indicate that the characteristics of the neighborhood influence people’s walks. these results corroborate zuniga-teran and colleagues’ (2017) findings, suggesting that a neighborhood that offers traffic safety combined with design elements improves the walking experience, including the nearby green space and easy access to these spaces. providing commercial destinations near residential areas (diversity of land use) with high residential density can encourage people to walk. places with good infrastructure attract people, and for that, it is necessary: continuous and preserved sidewalks, the appropriate location of urban furniture, which also contribute so that people with reduced mobility can also enjoy these public spaces, absence of high and high-speed traffic, trees street and landscaping and safety issues, both real and perceived by pedestrians (larrañaga et al., 2009; lo, 2009). all these aspects contribute to the streets being quality places for walking. identifying statistical differences between the respondents’ averages were carried out through the analysis of variance (anova). the purpose of this analysis was to identify differences in behavior according to the different profiles of respondents, especially between the sedentary and active groups. the sedentary profile (walking less than 20 minutes a day) represents 54.8% of the sample. statistically significant differences (p <0.050) were identified for: sedentary lifestyle, sex, and age group (table 5). a. dependent variable: walk generally speaking, it is easy to walk in my neighborhood. journal of sustainable architecture and civil engineering 2022/1/30 74 table 4 statistical differences between the respondents’ averages through anova variable f sig. result time spent walking per day 1099.89 0.000 non-sedentary people spend more time walking. 3.895 0.049 men spend more time walking. distance walking per day 333.10 0.000 non-sedentary people walk longer distances. 6.413 0.012 men walk longer distances compared to women. drivers drive at a safe speed 3.243 0.001 the perception that drivers drive at safe speeds increases with age. felling safe walking in the neighborhood 11.585 0.001 men feel safer than women when walking in the neighborhood. 2.055 0.032 people aged between 28 and 36 years old feel safer than others. sidewalks safety for people with mobility disabilities 5.660 0.014 non-sedentary people consider the sidewalks safer than sedentary people. 5.281 0.000 people aged between 28and 36-years old feel consider the sidewalks unsafety. presence of benches and places to sit 6.140 0.014 non-sedentary people agree that there are more benches and places to sit than sedentary ones. presence of trees and attractive places along the street 4.430 0.036 non-sedentary people agree that there are more trees and attractive places to sit than sedentary ones beauty of neighborhood area 2.221 0.020 the perception of the beauty of the neighborhood increases with age. ease of walking in the neighborhood. 5.710 0.017 non-sedentary people find walking in the neighborhood easier than sedentary ones. 4.484 0.035 men find walking in the neighborhood easier than women. both “time spent walking per day” and “distance walking per day” showed statistically significant differences regarding sex and physical inactivity (p <0.050): men and active people spend more time walking and travel greater distances per day. men also perceive that walking in the city is more accessible than women. regarding physical inactivity, the results show that this driver was the one that presented the most significant number of different perceptions. the perception of active people differs from the perception of sedentary people concerning four aspects (p <0.050): (i) sidewalk’s safety for people with mobility disabilities; (ii) presence of benches and places to sit; (iii) presence of trees and attractive places along the street; and (iv) ease of walking in the neighborhood. in all these aspects, active people have more favorable evaluations than sedentary people, showing that adopting walking habits also improves the city’s perception as a space that provides active mobility, social interaction, and quality of life (leslie et al., 2005). regarding the differences in perception according to the age group (p <0.050), the results show that older people have the perception that drivers drive more safely (perhaps because respondents have designed their attitudes in the assessment) and also has a more positive evaluation about urban space since the perception of the beauty of the neighborhood increases with age. the age group between 28 and 36 years old showed a difference in perception in two aspects (p <0.050): (i) they have higher felling safe walking in the neighborhood, and (ii) they consider sidewalk’s unsafety for people with mobility disabilities. the first aspect is related to urban violence, while the second is to perceive the need for pedestrians’ infrastructure (jayakody et al., 2018; mouraet al., 2017; cerin et al., 2006). 75 journal of sustainable architecture and civil engineering 2022/1/30 there is growing concern among nations about issues related to sustainability. researchers and urban planners have sought to identify the variables and methods to measure how sustainable a city is and how it impacts the lives of the people who live there, always seeking to minimize environmental impacts and improve the quality of life and the environment. one way is to consider active mobility, such as walking, which, in addition to not polluting, improves people’s health and well-being, but it also needs qualified environments for its encouragement. sustainable mobility is a positive indicator of what we all want replacing pollution, crime, traffic accidents as indicators of what we do not want and thus becomes a focus for collective action and involvement that recreates the community and takes care of each other and the places they share. this study aimed to identify the walkability driver in urban areas and investigate walkability drivers according to socio-demographic features. four walkability drivers were identified: infrastructure, traffic conditions and behavior, built and natural environments, and social relations. these drivers include both physical and psycho-social aspects linked to walkability. in this way, the study contributed to filling the gap of accessing subjective data to analyze pedestrians’ behavior according to the spaces’ morphology by identifying attitudes and behaviors about walking. regarding respondents’ general perception about the ease of adopting walking as active mobility, two aspects were more significant: the attractiveness and pleasure of walking in the neighborhood and the adhesion of more people walking and cycling. this result shows the importance of thinking and designing the neighborhoods, considering the infrastructure and the natural environment that privilege social interaction and active mobility. finally, socio-demographic aspects related to walkability were identified: the need to improve public security for women, young people, and the elderly; improve the quality of sidewalks for people with mobility disabilities; increase the presence of benches and places to sit, to encourage people who are sedentary or have reduced mobility; increase the number of trees and attractive places along the street, to encourage coexistence and improve the feeling of security. walkability is a central element in planning a sustainable city, and several drivers need to be reviewed. over the years, walking has taken on an exceptional character, as if it were not a natural alternative for human displacement. urban spaces are still, for the most part, idealized from the vehicle’s perspective, especially in developing countries. as the results pointed out, the design of spaces is fundamental to stimulate coexistence in urban life. thus, walkability depends on an understanding of walking behavior according to the morphology of the spaces. in sum, this work contributes theoretically and practically to several approaches. first, it identifies the walkability drivers in urban areas to provide the citizens’ perception of walkability as a subjective analysis. second, it explains socio-demographic 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s.e., guertin d.p., going s.b. designing healthy communities: testing the walkability model. frontiers of architectural research, 2017; 6(1): 6373. https://doi.org/10.1016/j.foar.2016.11.005 this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). about the authors jennifer domeneghini federal university of rio grande do sul (ufrgs) main research area territorial development adress rua sarmento leite, 320/5 andar porto alegre – 90050170 brasil tel.: +55 51 98538-7414 e-mail: jennidomeneghini@gmail.com janaina macke university of caxias do sul (ucs) main research area territorial development adress r. francisco getúlio vargas, 1130 – caxias do sul – 95.020972 brasil tel.: +55 54 98135-0241 e-mail: janaina.macke@gmail.com; jmacke@ucs.br joão alberto rubim sarate federal university of rio grande do sul (ufrgs) main research area territorial development adress r. simões lopes neto, 522/1001 – caxias do sul – 95.054-400 brasil tel.: +55 54 98135-0429 e-mail: jasarate@gmail.com journal of sustainable architecture and civil engineering 2020/2/27 116 *corresponding author: mindaugas.dauksys@ktu.lt research on installation technology of floating stone columnsreceived 2020/09/02 accepted after revision 2020/09/24 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 116 -125 doi 10.5755/j01.sace.27.2.27580 research on installation technology of floating stone columns jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.27580 vytenis girčys, mindaugas daukšys*, svajūnas juočiūnas kaunas university of technology, faculty of civil engineering and architecture, studentų str. 48, lt-51367 kaunas, lithuania introduction in this study three already finished projects in lithuania were investigated, the problems faced in the projects were examined, and the main advantages and drawbacks of the chosen geopile installation technology were identified. three alternative solutions for geopile installation were selected for the investigation: driving a hollow steel pipe into the ground using a deep vibrator and using geosynthetic material to reinforce soils (a1); driving a closed-ended hollow steel pipe into the ground and using geosynthetic material to reinforce soils (a2); driving an open-ended hollow steel pipe into the ground and using geosynthetic material to reinforce soils (a3). those alternatives were evaluated according to the following criteria: geopile installation cost (k1), level of mechanization (k2), load bearing capacity (k3), installation options (k4), impact on the environment (k5), duration of the installation of geopiles (k6). in order to find out the significance of the evaluation criteria a survey questionnaire and a ranking procedure were used. the same order of criteria importance, namely k1>k3> k2>k4>k6>k5, was obtained using the selected rank-order weighting method. basing on the selected criteria, a rational option for geopile foundations was identified using the multi-criteria assessment method topsis. the results show that driving an open-ended hollow steel pipe into the ground and using geosynthetic material to reinforce soils (a3) is the most rational option for the installation of geopiles in the investigated finished projects in lithuania. this article is based on master thesis topic “research on installation technology of geopiles”. keywords: ground properties, floating stone columns, geopiles, geopile installation technology. with the rapid development of urbanization level and changing climatic conditions, lithuania is increasingly facing negative water effect on roads, street sites and city infrastructure. construction starts in places where people would never have thought about them before. increasingly, structures are being erected in peat-lands or flooded areas. as cities grow and expand, the infrastructure they need is growing and expanding too. in 2018 alone, the lithuanian government allocated almost half a billion euros for the development of road infrastructure. the infrastructure construction industry often usually faces peaty or flooded areas and related problems. all over the world, including lithuania, the aim is to build roads, railways or footpaths so that they can be used as long as possible. there are several ways to deal with the construction of new roads or buildings in the face of unfavourable building conditions. 117 journal of sustainable architecture and civil engineering 2020/2/27 in literature, geopiles are called differently: geosynthetic piles, ground piles, stone columns, etc. geopiles are a type of piles. their main distinguishing feature is that the geopiles aggregate is an impermeable, draining, mostly mineral material. construction waste ground to a medium fraction may also be used as aggregate. since geopiles can only take on very small transverse loads, they are most often used in places where such loads are virtually non-existent, underneath bollards, roads or railways, transport infrastructure structures, building floors or storage sites (pivarč 2011, tandel 2013, ng 2014, das 2014, ng 2015, ng 2016). there are various technologies for laying geopile foundations in the world, but only the most popular and the most widespread technologies are analysed in this article. at present only two technologies are used in lithuania: geopile installation driving a forged pipe and geopile installation driving a close-ended hollow steel tube. in order to ensure the bearing capacity of geopiles, it is the most appropriate to use an open-ended hollow steel pipe using geosynthetic material as driving an open-ended hollow steel tube pushes the tube until a response is achieved, and the response can be achieved for a variety of reasons (weak soil compression, suction, a stronger soil interlayer or larger stone). the use of an open-ended hollow steel pipe technology ensures the load-bearing capacity of the geopiles, thus protecting the structure from collapse. installation of geopiles using a deep vibrator is the most common method in south america, africa and southern europe due to the prevalence of water-saturated thick layers of fluid clay. geopiles installed using a deep vibrator are often referred to as crushed stone pillars. crushed stone pillars are installed from the bottom up. during vibration, reversible movement (two steps up, one down) is used to press the column aggregate (crushed stone, gravel or gravel sand) from the cavity in the upper part of the vibrator into the clutch soil. this allows to compact the poured aggregate and increase the diameter of the column (sližytė 2012). the installation of such columns using vibration in clay soil is sometimes referred to as vibrational soil replacement, although this term is not precise local soil is not replaced but pushed aside, filling the cavity formed by the vibrator with coarse aggregate. it is desirable to use crushed stone or gravel as an aggregate, although in exceptional cases sand could be used if it were too difficult and expensive to bring coarse aggregate. using this technology, the installation of columns next to each other can create a reinforced base pillow. however, this technology is not widespread in lithuania, and even little known. this is due to the technological difficulty of installing long piles when using a deep vibrator. usually the length of the piles using this technology is 6-7 meters. however, in lithuania, where soil reinforcement is required, strong soil is found in deeper layers. crushed stone columns are installed at the locations provided in the project. inventory steel pipe 3050 cm in diameter with a special closing and opening spike is plunged into the soil through the entire depth of the substrate deformation zone or to a strong soil where the weak soil layer is thinner than the deformation zone. by dredging the inventory pipe, the soil is compacted, as in the case of a pile, in a zone of approximately 3 d (where d is the diameter of the pipe). water from the soil is squeezed through adjacent previously made rubble columns, resulting in a significant compaction of soil. deep soil vibrator is a device for spreading and compacting coarse soil in weak soils. this device is mounted on a pile-driver. there are different types and capacities of deep soil vibrators. geopile installation technology driving an open-ended hollow steel pipe using geosynthetic material can only be used in low adhesion soils. soil adhesion cu <15 kpa (peat, soft clay). the strength of these geopiles is higher due to the use of the geosynthetic material. as geotextile takes over tensile stresses, small transverse stresses can also be transmitted to the pile. as the aggregate is poured into the geosynthetic material, it does not mix with the weak soil, forming a round cross-sectional pile (sližytė 2012). journal of sustainable architecture and civil engineering 2020/2/27 118 this technology is the fastest for geopile installation, but its use is limited due to the high vibration pressure in the pipe. the minimum distance from existing structures must be at least 25m. the aggreagte in the geotextile is compacted by pulling the forged pipe. after installation, the pile-driver moves to the design position of the next pile. often, several inventory pipes with special heads are used so that the pile-driver does not have to wait for the geotextile bag to be filled. geopile installation technology driving an open-ended hollow steel pipe using geosynthetic material can be used in low adhesion or medium-strength soils (sarvaiya 2017). soil adhesion cu <30 kpa (peat, soft clay, loose soils, construction waste). the strength of these geopiles is higher due to the use of the geotextile shell. as geotextile takes over tensile stresses, small transverse stresses can also be transmitted to the pile. as the aggregate is poured into the geosynthetic material, it does not mix with the weak soil, forming a round cross-sectional pile (sližytė 2012). with this technology, geopiles are installed at a slightly slower rate than with a forged pipe, but due to the minimal vibrations generated during installation, these piles can be installed close to existing structures, it is only necessary to provide a protective distance for the drilling head. the minimum distance from existing structures must be at least 0.8 m (sližytė 2012). the aim of this work is to investigate three finished projects in lithuania, to examine the problems faced in the projects, and to identify the main advantages and drawbacks of the chosen geopile installation technology. methods for the analysis of geopile foundation installation three finished projects in lithuania were chosen for the research. information about the chosen projects is provided in table 1. three alternative solutions for geopile installation in this research were selected for the analysis: _ driving a hollow steel pipe into the ground using a deep vibrator and using geosynthetic material to reinforce soils (a1); _ driving a close-ended hollow steel pipe into the ground and using geosynthetic material to reinforce soils (a2); _ driving an open-ended hollow steel pipe into the ground and using geosynthetic material to reinforce soils (a3). the geopile foundation alternatives chosen in the article will be evaluated according to the following criteria: k1 pile installation cost (eur) is a quantitative, economic indicator that measures the cost of installing one meter of pile. the cost is calculated based on the analysis of the completed projects. k2 the level of mechanization is a qualitative indicator expressed in terms of the degree of mechanics involved. this indicator is determined by an expert method. k3 load-bearing capacity is a qualitative score-based indicator that measures the ability of geopiles to withstand loads transmitted by structures. the bearing capacity of geopiles depends on the ground conditions, the dimensions of the pile, the method of installation, etc. the indicator is determined by an expert method. k4 installation options a qualitative, score-based indicator that assesses the complexity of geopile installation, site conditions, and access. the indicator depends on the power and quantity of machinery used, materials needed for installation, etc. this indicator is determined by an expert method. k5 impact on the environment a qualitative indicator of the environmental damage caused by the installation of geopiles (noise, vibration, earthworks, etc.). the indicator depends on the pile-driving technique, the method of pile-driving, the materials used for piles, etc. this indicator is determined by an expert method. k6 duration of the installation of geopiles is a score-based quantitative indicator that measures the duration of pile installation. this indicator is determined by an expert method. 119 journal of sustainable architecture and civil engineering 2020/2/27 investigation object advantage of used technology disadvantage of used technology object no 1: construction work for the modernization of rambynas border checkpoint. problem: geological surveys have shown that 5-6 m thick peat and silt layers are found throughout the area. because the area is very large and the layer of weak soil is thick, replacing a weak soil with a strong one would be very expensive, so it was decided to look for alternative ways to reinforce the foundation. solution: to transfer the loads acting on the area into strong soils that lie deeper beneath the whole area, geopiles have been designed. the geopiles are arranged in a 2.6 × 2.6 m grid, with a pile diameter of 0.8 m and a pile length ranging from 6 to 7 m. by using prefabricated reinforced concrete slabs to increase the footprint of the 1.2 × 1.2 × 0.15 m piles, this solution saves even more time on contract work. the geo-grid structure is equipped with a geo-grid-reinforced soil dam. in total, more than 5.600 geopiles have been installed. the piles are installed driving an open-ended hollow steel pipe using geosynthetic material. ensures that the pile is installed to the required depth. no high vibrations. can be installed with lower efficiency machinery. a large amount of fossil soil is generated, which is unsuitable for further work and needs to be removed from the construction site, resulting in additional transport costs for soil. object no. 2: installation of vaižganto street in utena between j.basanavičiaus and pievu streets. problem: geological surveys have revealed that there is peat under a large part of the newly designed street. because of the high thickness of the peat layer, replacing a weak soil with a strong one would be very costly, so it was decided to look for alternative ways to reinforce the foundation. solution: it was decided to install the street structure on the platform of geopiles and geogrids. the geopiles are arranged in a 2.2 × 2.2 m grid, with a pile diameter of 0.8 m and a pile length of about 11 m. to increase the footprint of the 1.2 × 1.2 × 0.15 m piles, pre-fabricated reinforced concrete slabs further save time on contract work. the geo-grid structure is equipped with a geo-grid-backed platform. in total 840 geopiles are installed. the piles are installed driving an open-ended hollow steel pipe using geosynthetic material. ensures that the pile is installed to the required depth. no high vibrations. can be installed with lower efficiency machinery. a large amount of fossil soil is generated, which is unsuitable for further work and needs to be removed from the construction site, resulting in additional transport costs for soil. object no. 3: reconstruction of state road no.144 jonava kėdainiai šeduva from 76.4 to 90.508 km. problem: geological surveys have shown that under the reconstructed road there are layers of weak gray soil with a thickness of up to 12 m. replacing a weak soil with a strong one would be very expensive, so it was decided to look for alternative ways to reinforce the foundation. solution: it was decided to install the road structure on the platform of geopiles and geogrids. the geopiles are arranged in a grid of 1.5 × 1.5 m, a pile diameter of 0.6 m and a pile length of up to 13.5 m. a 22000 m geotextile shell was used. the geo-grid structure is equipped with a geo-grid-backed platform. the piles are installed driving an open-ended hollow steel pipe using geosynthetic material. piles are installed faster. there is no additional soil to be removed from the construction site. it is difficult to ensure that the piles are sufficiently deepened into the supporting soil. due to the high vibration, the surrounding soil is liquefied, making it difficult for construction machinery and workers to move. high-capacity construction machinery is required to forge the pipe. table 1 information about the chosen projects journal of sustainable architecture and civil engineering 2020/2/27 120 a questionnaire was prepared based on the analysis of literature sources and selected geopile technology assessment criteria. this questionnaire was sent to companies operating in lithuania, which specialize in geopile installation or have facilities to install it. survey participants were able to rank the criteria in the questionnaire to find out the significance of the criteria. respondents were asked to record scores from 1 to 10 for each criterion, which would indicate the importance of the criteria. the evaluation is carried out in the following way: first, the most important evaluation criterion is selected, the significance of which is equal to 10 scores (there may be several criteria). the remaining criteria are then compared to the most important criterion. the purpose of quantitative multiple criteria decision making (mcdm) methods is to determine the best of the alternatives to be compared or to rank them in relation to the purpose of the assessment. one of the most important components of these methods is the weighting of the criteria used in the research. the importance of individual criteria describing the influence of the research object on the examined aim is different, therefore it is important to determine the significance of the criteria, i. y. their weights (podvezko 2013, simanavičienė 2015). most of the currently known and applied multi-criteria weighting methods are based on expert assessment. the subjective basis for determining criteria weights is based on expert assessment. the opinions of individual experts are often contradictory and sometimes may be contradictory; therefore, the importance and priority of the individual expert evaluation criteria will vary. assessment depends on the qualifications of the experts, the specifics of the job, the interest in obtaining certain assessment results, seniority and so on. criteria weights as summarized averages of expert opinions can be used in a multi-criteria assessment if consistency in the expert assessments has been identified, i. y. opinions have been shown to be statistically consistent. the kendall’s coefficient of concordance can be used to determine the consistency of assessment (herve 2007). whatever the subjective method of weighting, the assessment process should start with the ranking of the criteria. ranking is the procedure when the most important criterion is given the highest rank – rank one, the second most important rank two and so on, i.e., the last criterion is given the rank m, where m is the number of criteria to be compared. equivalent criteria are given the same value the arithmetic mean of ordinary ranks. the method is easy to apply in practice, but it should be emphasized that the method has low accuracy. regardless of the assessment methods used, expert assessments are marked as cik (i = 1,..., m; k = 1,..., r), where m is the number of criteria used, r is the number of experts (ginevičius. 2004). assessment results are placed in the matrix c = || cik ||. a number of criteria weighting algorithms can be introduced where criteria weighting rankings are used. the purpose of conversion is to assign weights in descending order of rank. thus the top rank (first) is given the highest value. the most accurate result is provided by the linear transformation of assessment. in this case, the values of the criteria weights can be calculated according to (1) equation: here: m is the number of criteria to be compared; r number of experts the purpose of quantitative multiple criteria decision making (mcdm) methods is to determine the best of the alternatives to be compared or to rank them in relation to the purpose of the assessment. one of the most important components of these methods is the weighting of the criteria used in the research. the importance of individual criteria describing the influence of the research object on the examined aim is different, therefore it is important to determine the significance of the criteria, i. y. their weights (podvezko 2013, simanavičienė 2015). most of the currently known and applied multi-criteria weighting methods are based on expert assessment. the subjective basis for determining criteria weights is based on expert assessment. the opinions of individual experts are often contradictory and sometimes may be contradictory; therefore, the importance and priority of the individual expert evaluation criteria will vary. assessment depends on the qualifications of the experts, the specifics of the job, the interest in obtaining certain assessment results, seniority and so on. criteria weights as summarized averages of expert opinions can be used in a multi-criteria assessment if consistency in the expert assessments has been identified, i. y. opinions have been shown to be statistically consistent. the kendall’s coefficient of concordance can be used to determine the consistency of assessment (herve 2007). whatever the subjective method of weighting, the assessment process should start with the ranking of the criteria. ranking is the procedure when the most important criterion is given the highest rank – rank one, the second most important rank two and so on, i.e., the last criterion is given the rank m, where m is the number of criteria to be compared. equivalent criteria are given the same value the arithmetic mean of ordinary ranks. the method is easy to apply in practice, but it should be emphasized that the method has low accuracy. regardless of the assessment methods used, expert assessments are marked as cik (i = 1,..., m; k = 1,..., r), where m is the number of criteria used, r is the number of experts (ginevičius. 2004). assessment results are placed in the matrix c = || cik ||. a number of criteria weighting algorithms can be introduced where criteria weighting rankings are used. the purpose of conversion is to assign weights in descending order of rank. thus the top rank (first) is given the highest value. the most accurate result is provided by the linear transformation of assessment. in this case, the values of the criteria weights can be calculated according to (1) equation: (1) here: m is the number of criteria to be compared; r number of experts. determination of criterion weights using direct and indirect assessments. these methods have a higher accuracy compared to the ranking method. applying the direct criterion weighting method, the sum of all assessment weightings cik must be equal to 1 (or 100%). the method of indirect criteria weighting uses the selected scoring system (5, 10, 20, etc.) (ginevičius, 2004). assessments can be repeated. the criteria weights are calculated on the basis of direct and indirect assessment according to (2) equation: (2) å å å = = = -+ -+ = m i r k ik r k ik i cm cm 1 1 1 )1( )1( w å å å = = == m i r k ik r k ik i c c 1 1 1w (1) determination of criterion weights using direct and indirect assessments. these methods have a higher accuracy compared to the ranking method. applying the direct criterion weighting method, the sum of all assessment weightings cik must be equal to 1 (or 100%). the method of indirect criteria weighting uses the selected scoring system (5, 10, 20, etc.) (ginevičius, 2004). assessments can be repeated. the criteria weights are calculated on the basis of direct and indirect assessment according to (2) equation: 121 journal of sustainable architecture and civil engineering 2020/2/27 table 1 initial matrix a of alternative solutions criterions alternative solutions k1, pile installation cost k2, the level of mechanization k3, load-bearing capacity k4, installation options k5, impact on the enviroment k6, duration of the installation a1 … … … … … … a2 … … … … … … a3 … … … … … … the topsis method was chosen for the multi-criteria assessment. the essence of the method is to determine which solution is the closest or the farthest to the ideal point. this means that the best solution will be the closest to the ideal and the worst will be the farthest. assume that the values of each indicator are constantly increasing or decreasing. it is then possible to determine the "ideal" solution that consists of the best indicator values and the "negatively ideal" solution that consists of the worst indicator values. to apply the proximity to the ideal point method, it is necessary to construct a solution matrix or provide data on alternative solutions (simanavičienė, 2015). normalization of matrix b to matrix . because the b measurement criteria in the matrix are different units of measurement, we cannot compare alternative engineering solutions. for this reason, it is necessary to normalize the matrix b, i. y. resized to dimensionless dimensions. matrix b normalization is performed using the vector normalization method (simanavičienė, 2015) according to (3) equation: (3) here: xij – i – line and j – column of matrix. table 1. initial matrix a of alternative solutions kriterijai criterions alternative solutions k1, pile installation cost k2, the level of mechanization k3, loadbearing capacity k4, installation options k5, impact on the enviroment k6, duration of the installation a1 … … … … … … a2 … … … … … … a3 … … … … … … … … … … … … optimality min max max max min min theoretical significance, % … … … … … … following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (4) equation (simanavičienė 2015): b* = [b] · [q], (4) the ideal best condition a+ (the best value) variant is adjustable by (5) equation (simanavičienė 2015): b å = = m i ij ij ij x x x 1 2 å = m i ijx 1 2 … … … … … … optimality min max max max min min theoretical significance, % … … … … … … the purpose of quantitative multiple criteria decision making (mcdm) methods is to determine the best of the alternatives to be compared or to rank them in relation to the purpose of the assessment. one of the most important components of these methods is the weighting of the criteria used in the research. the importance of individual criteria describing the influence of the research object on the examined aim is different, therefore it is important to determine the significance of the criteria, i. y. their weights (podvezko 2013, simanavičienė 2015). most of the currently known and applied multi-criteria weighting methods are based on expert assessment. the subjective basis for determining criteria weights is based on expert assessment. the opinions of individual experts are often contradictory and sometimes may be contradictory; therefore, the importance and priority of the individual expert evaluation criteria will vary. assessment depends on the qualifications of the experts, the specifics of the job, the interest in obtaining certain assessment results, seniority and so on. criteria weights as summarized averages of expert opinions can be used in a multi-criteria assessment if consistency in the expert assessments has been identified, i. y. opinions have been shown to be statistically consistent. the kendall’s coefficient of concordance can be used to determine the consistency of assessment (herve 2007). whatever the subjective method of weighting, the assessment process should start with the ranking of the criteria. ranking is the procedure when the most important criterion is given the highest rank – rank one, the second most important rank two and so on, i.e., the last criterion is given the rank m, where m is the number of criteria to be compared. equivalent criteria are given the same value the arithmetic mean of ordinary ranks. the method is easy to apply in practice, but it should be emphasized that the method has low accuracy. regardless of the assessment methods used, expert assessments are marked as cik (i = 1,..., m; k = 1,..., r), where m is the number of criteria used, r is the number of experts (ginevičius. 2004). assessment results are placed in the matrix c = || cik ||. a number of criteria weighting algorithms can be introduced where criteria weighting rankings are used. the purpose of conversion is to assign weights in descending order of rank. thus the top rank (first) is given the highest value. the most accurate result is provided by the linear transformation of assessment. in this case, the values of the criteria weights can be calculated according to (1) equation: (1) here: m is the number of criteria to be compared; r number of experts. determination of criterion weights using direct and indirect assessments. these methods have a higher accuracy compared to the ranking method. applying the direct criterion weighting method, the sum of all assessment weightings cik must be equal to 1 (or 100%). the method of indirect criteria weighting uses the selected scoring system (5, 10, 20, etc.) (ginevičius, 2004). assessments can be repeated. the criteria weights are calculated on the basis of direct and indirect assessment according to (2) equation: (2) å å å = = = -+ -+ = m i r k ik r k ik i cm cm 1 1 1 )1( )1( w å å å = = == m i r k ik r k ik i c c 1 1 1w (2) the topsis method was chosen for the multi-criteria assessment. the essence of the method is to determine which solution is the closest or the farthest to the ideal point. this means that the best solution will be the closest to the ideal and the worst will be the farthest. assume that the values of each indicator are constantly increasing or decreasing. it is then possible to determine the “ideal” solution that consists of the best indicator values and the “negatively ideal” solution that consists of the worst indicator values. to apply the proximity to the ideal point method, it is necessary to construct a solution matrix or provide data on alternative solutions (simanavičienė, 2015). normalization of matrix b to matrix b . because the b measurement criteria in the matrix are different units of measurement, we cannot compare alternative engineering solutions. for this reason, it is necessary to normalize the matrix b, i. y. resized to dimensionless dimensions. matrix b normalization is performed using the vector normalization method (simanavičienė, 2015) according to (3) equation: the topsis method was chosen for the multi-criteria assessment. the essence of the method is to determine which solution is the closest or the farthest to the ideal point. this means that the best solution will be the closest to the ideal and the worst will be the farthest. assume that the values of each indicator are constantly increasing or decreasing. it is then possible to determine the "ideal" solution that consists of the best indicator values and the "negatively ideal" solution that consists of the worst indicator values. to apply the proximity to the ideal point method, it is necessary to construct a solution matrix or provide data on alternative solutions (simanavičienė, 2015). normalization of matrix b to matrix . because the b measurement criteria in the matrix are different units of measurement, we cannot compare alternative engineering solutions. for this reason, it is necessary to normalize the matrix b, i. y. resized to dimensionless dimensions. matrix b normalization is performed using the vector normalization method (simanavičienė, 2015) according to (3) equation: (3) here: xij – i – line and j – column of matrix. table 1. initial matrix a of alternative solutions kriterijai criterions alternative solutions k1, pile installation cost k2, the level of mechanization k3, loadbearing capacity k4, installation options k5, impact on the enviroment k6, duration of the installation a1 … … … … … … a2 … … … … … … a3 … … … … … … … … … … … … optimality min max max max min min theoretical significance, % … … … … … … following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (4) equation (simanavičienė 2015): b* = [b] · [q], (4) the ideal best condition a+ (the best value) variant is adjustable by (5) equation (simanavičienė 2015): b å = = m i ij ij ij x x x 1 2 å = m i ijx 1 2 (3) here: xij – i – line and j – column of matrix following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (4) equation (simanavičienė 2015): the topsis method was chosen for the multi-criteria assessment. the essence of the method is to determine which solution is the closest or the farthest to the ideal point. this means that the best solution will be the closest to the ideal and the worst will be the farthest. assume that the values of each indicator are constantly increasing or decreasing. it is then possible to determine the "ideal" solution that consists of the best indicator values and the "negatively ideal" solution that consists of the worst indicator values. to apply the proximity to the ideal point method, it is necessary to construct a solution matrix or provide data on alternative solutions (simanavičienė, 2015). normalization of matrix b to matrix . because the b measurement criteria in the matrix are different units of measurement, we cannot compare alternative engineering solutions. for this reason, it is necessary to normalize the matrix b, i. y. resized to dimensionless dimensions. matrix b normalization is performed using the vector normalization method (simanavičienė, 2015) according to (3) equation: (3) here: xij – i – line and j – column of matrix. table 1. initial matrix a of alternative solutions kriterijai criterions alternative solutions k1, pile installation cost k2, the level of mechanization k3, loadbearing capacity k4, installation options k5, impact on the enviroment k6, duration of the installation a1 … … … … … … a2 … … … … … … a3 … … … … … … … … … … … … optimality min max max max min min theoretical significance, % … … … … … … following the normalization of matrix b, a weighted normalized matrix b*of alternative solutions is created. to this end the normalized matrix b is multiplied by the vector of criteria weight using (4) equation (simanavičienė 2015): b* = [b] · [q], (4) the ideal best condition a+ (the best value) variant is adjustable by (5) equation (simanavičienė 2015): b å = = m i ij ij ij x x x 1 2 å = m i ijx 1 2 (4) journal of sustainable architecture and civil engineering 2020/2/27 122 ( ) { };;;,1//min,/max 321' ++++ = þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ijjiji (5) ( ) { };;;,1//max,/min 321' ---= þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ij j iji (6) (5) and the ideal worst condition a(the worst value) are found by (6) equation (zavadskas, e. k. 2001): (6) distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed according to (7,8) equations (simanavičienė 2015): , (7) , (8) the relative proximity of compared options to the ideal option is found, i.e. criterion is calculated using (9) equation (simanavičienė, 2015): , ; when (9) having the criterion value calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion . in the last stage the degree of utility of compared options is calculated using (10) equation: (10) the most rational engineering option is the one with the highest value (simanavičienė 2015). then the degree of utility’s calculated according to equation 10 to compare the value of the analysed option with the value of the ideal option. results as the technology of geopile foundation installation is specific in lithuania and all over the world, only 18 respondents were able to answer the questionnaire. the distribution of respondents who participated in the survey according to their current position is presented in figure 1. ( ) { };;;,1//min,/max 321' ++++ = þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ijjiji ( ) { };;;,1//max,/min 321' ---= þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ij j iji + = + -=å j n j iji aas 1 ),1( mi = = -=å j n j iji aas 1 ),1( mi = ic -+ + = ii i i ss s c mi ,1= ]1,0[îic ic ic ln %100 max, , ×= i li l c c n (7) (5) and the ideal worst condition a(the worst value) are found by (6) equation (zavadskas, e. k. 2001): (6) distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed according to (7,8) equations (simanavičienė 2015): , (7) , (8) the relative proximity of compared options to the ideal option is found, i.e. criterion is calculated using (9) equation (simanavičienė, 2015): , ; when (9) having the criterion value calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion . in the last stage the degree of utility of compared options is calculated using (10) equation: (10) the most rational engineering option is the one with the highest value (simanavičienė 2015). then the degree of utility’s calculated according to equation 10 to compare the value of the analysed option with the value of the ideal option. results as the technology of geopile foundation installation is specific in lithuania and all over the world, only 18 respondents were able to answer the questionnaire. the distribution of respondents who participated in the survey according to their current position is presented in figure 1. ( ) { };;;,1//min,/max 321' ++++ = þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ijjiji ( ) { };;;,1//max,/min 321' ---= þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ij j iji + = + -=å j n j iji aas 1 ),1( mi = = -=å j n j iji aas 1 ),1( mi = ic -+ + = ii i i ss s c mi ,1= ]1,0[îic ic ic ln %100 max, , ×= i li l c c n (8) results the ideal best condition a+ (the best value) variant is adjustable by (5) equation (simanavičienė 2015): and the ideal worst condition a(the worst value) are found by (6) equation (zavadskas, e. k. 2001): distances between the real option ai and the ideal best condition a +, as well as between the real option ai and the ideal worst condition a are computed according to (7,8) equations (simanavičienė 2015): the relative proximity of compared options to the ideal option is found, i.e. criterion ci is calculated using (9) equation (simanavičienė, 2015): (5) and the ideal worst condition a(the worst value) are found by (6) equation (zavadskas, e. k. 2001): (6) distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed according to (7,8) equations (simanavičienė 2015): , (7) , (8) the relative proximity of compared options to the ideal option is found, i.e. criterion is calculated using (9) equation (simanavičienė, 2015): , ; when (9) having the criterion value calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion . in the last stage the degree of utility of compared options is calculated using (10) equation: (10) the most rational engineering option is the one with the highest value (simanavičienė 2015). then the degree of utility’s calculated according to equation 10 to compare the value of the analysed option with the value of the ideal option. results as the technology of geopile foundation installation is specific in lithuania and all over the world, only 18 respondents were able to answer the questionnaire. the distribution of respondents who participated in the survey according to their current position is presented in figure 1. ( ) { };;;,1//min,/max 321' ++++ = þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ijjiji ( ) { };;;,1//max,/min 321' ---= þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ij j iji + = + -=å j n j iji aas 1 ),1( mi = = -=å j n j iji aas 1 ),1( mi = ic -+ + = ii i i ss s c mi ,1= ]1,0[îic ic ic ln %100 max, , ×= i li l c c n (9) having the criterion ci value calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion ci. in the last stage the degree of utility nl of compared options is calculated using (10) equation: (5) and the ideal worst condition a(the worst value) are found by (6) equation (zavadskas, e. k. 2001): (6) distances between the real option ai and the ideal best condition a+, as well as between the real option ai and the ideal worst condition aare computed according to (7,8) equations (simanavičienė 2015): , (7) , (8) the relative proximity of compared options to the ideal option is found, i.e. criterion is calculated using (9) equation (simanavičienė, 2015): , ; when (9) having the criterion value calculated, the priority rank of compared options is made. in our case, the best option is the one that has the highest value of criterion . in the last stage the degree of utility of compared options is calculated using (10) equation: (10) the most rational engineering option is the one with the highest value (simanavičienė 2015). then the degree of utility’s calculated according to equation 10 to compare the value of the analysed option with the value of the ideal option. results as the technology of geopile foundation installation is specific in lithuania and all over the world, only 18 respondents were able to answer the questionnaire. the distribution of respondents who participated in the survey according to their current position is presented in figure 1. ( ) { };;;,1//min,/max 321' ++++ = þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ijjiji ( ) { };;;,1//max,/min 321' ---= þ ý ü î í ì =úû ù êë é ÷ ø öç è æ îî= aaamijjxjjxa ij j iji + = + -=å j n j iji aas 1 ),1( mi = = -=å j n j iji aas 1 ),1( mi = ic -+ + = ii i i ss s c mi ,1= ]1,0[îic ic ic ln %100 max, , ×= i li l c c n (10) the most rational engineering option is the one with the highest value (simanavičienė 2015). then the degree of utility’s calculated according to equation 10 to compare the value of the analysed option with the value of the ideal option. as the technology of geopile foundation installation is specific in lithuania and all over the world, only 18 respondents were able to answer the questionnaire. the distribution of respondents who participated in the survey according to their current position is presented in fig. 1. the first survey questionnaire was answered mainly by company managers and salespeople, the number of respondents 8, which made up 44%. in the second place design engineers, 7 respondents, which made 39%, and in the third place according to the number of answers were work supervisors, 3 respondents, which made up 17%. the answers to the survey were distributed according to 123 journal of sustainable architecture and civil engineering 2020/2/27 the occupations of the respondents. for design engineers the most important assessment criterion was bearing capacity, while managers ranked the installation price as the most important. after ranking the criteria, it was found that the most important criterion when choosing geopile installation technology is installation price (eur/m), the second place – load-bearing capacity (in scores), the third place installation technology mechanization level (in scores), the fourth place – pile installation possibilities (in scores), the fifth place the duration of pile installation (in scores), and the sixth place – the impact of pile installation techfig. 1 distribution of respondents by position fig. 1. distribution of respondents by position the first survey questionnaire was answered mainly by company managers and salespeople, the number of respondents 8, which made up 44%. in the second place design engineers, 7 respondents, which made 39%, and in the third place according to the number of answers were work supervisors, 3 respondents, which made up 17%. the answers to the survey were distributed according to the occupations of the respondents. for design engineers the most important assessment criterion was bearing capacity, while managers ranked the installation price as the most important. after ranking the criteria, it was found that the most important criterion when choosing geopile installation technology is installation price (eur/m), the second place – load-bearing capacity (in scores), the third place installation technology mechanization level (in scores), the fourth place – pile installation possibilities (in scores), the fifth place the duration of pile installation (in scores), and the sixth place – the impact of pile installation technology on the environment (in scores). criteria are ranked applying the direct ranking method (selected score scale 6 ... 1), which means that the highest scoring criterion will receive the highest rank score, i.e. 6; the second will receive 5 and so on. fig.2. the scores obtained by the criteria in the survey of respondents fig. 1. distribution of respondents by position the first survey questionnaire was answered mainly by company managers and salespeople, the number of respondents 8, which made up 44%. in the second place design engineers, 7 respondents, which made 39%, and in the third place according to the number of answers were work supervisors, 3 respondents, which made up 17%. the answers to the survey were distributed according to the occupations of the respondents. for design engineers the most important assessment criterion was bearing capacity, while managers ranked the installation price as the most important. after ranking the criteria, it was found that the most important criterion when choosing geopile installation technology is installation price (eur/m), the second place – load-bearing capacity (in scores), the third place installation technology mechanization level (in scores), the fourth place – pile installation possibilities (in scores), the fifth place the duration of pile installation (in scores), and the sixth place – the impact of pile installation technology on the environment (in scores). criteria are ranked applying the direct ranking method (selected score scale 6 ... 1), which means that the highest scoring criterion will receive the highest rank score, i.e. 6; the second will receive 5 and so on. fig.2. the scores obtained by the criteria in the survey of respondents in order to determine a rational geopile installation solution, a multi-criteria task is solved, i.e. three alternatives are compared by assessing them according to 6 criteria, and the initial matrix is presented in table 2. table 2. initial matrix a of alternative solutions kriterijai criterion alternative solutions k1 k2 k3 k4 k5 k6 a1 9.0 28 25 20 27 30 a2 11.0 27 31 24 21 28 a3 12.5 27 29 31 18 24 18.9 47.3 49.3 44.0 38.7 47.5 optimality min max max max max max theoretical significance, % 28.6 19.5 23.8 14.3 4.8 9.5 å = m i ijx 1 2 fig. 3. criteria weight distribution by theoretical significance nology on the environment (in scores). criteria are ranked applying the direct ranking method (selected score scale 6 ... 1), which means that the highest scoring criterion will receive the highest rank score, i.e. 6; the second will receive 5 and so on. fig. 2 the scores obtained by the criteria in the survey of respondents fig. 3 criteria weight distribution by theoretical significance journal of sustainable architecture and civil engineering 2020/2/27 124 in order to determine a rational geopile installation solution, a multi-criteria task is solved, i.e. three alternatives are compared by assessing them according to 6 criteria, and the initial matrix is presented in table 2. table 2 initial matrix a of alternative solutions criterion alternative solutions k1 k2 k3 k4 k5 k6 a1 9.0 28 25 20 27 30 a2 11.0 27 31 24 21 28 a3 12.5 27 29 31 18 24 in order to determine a rational geopile installation solution, a multi-criteria task is solved, i.e. three alternatives are compared by assessing them according to 6 criteria, and the initial matrix is presented in table 2. table 2. initial matrix a of alternative solutions kriterijai criterion alternative solutions k1 k2 k3 k4 k5 k6 a1 9.0 28 25 20 27 30 a2 11.0 27 31 24 21 28 a3 12.5 27 29 31 18 24 18.9 47.3 49.3 44.0 38.7 47.5 optimality min max max max max max theoretical significance, % 28.6 19.5 23.8 14.3 4.8 9.5 å = m i ijx 1 2 fig. 3. criteria weight distribution by theoretical significance 18.9 47.3 49.3 44.0 38.7 47.5 optimality min max max max max max theoretical significance, % 28.6 19.5 23.8 14.3 4.8 9.5 a multi-criteria assessment was performed and it was found, that that a rational geopile installation technology is the use of an open-ended hollow steel pipe using geosynthetic material. this is not the cheapest way to install a pile, but it is in the most optimal of all criteria. this technology has a particularly wide range of installation options, good load-bearing capacity and assurance of load-bearing capacity. fig. 4. schedule of alternate utility degrees. here: a1 – driving a hollow steel pipe into the ground using a deep vibrator and using geosynthetic material to reinforce soils; a2 – driving a closed end hollow steel pipe into the ground and using geosynthetic material to reinforce soils; a3 – driving an open-ended hollow steel pipe into the ground and using geosynthetic material to reinforce soils a multi-criteria assessment was performed and it was found, that that a rational geopile installation technology is the use of an open-ended hollow steel pipe using geosynthetic material. this is not the cheapest way to install a pile, but it is in the most optimal of all criteria. this technology has a particularly wide range of installation options, good load-bearing capacity and assurance of loadbearing capacity. conclusions 1. according to the survey questionnaire data, the ranking order of the assessment criteria is as follows: installation cost (eur), load-bearing capacity (in scores), mechanization level of the installation technology (in scores), pile installation possibilities (in scores), duration of pile installation (in scores), impact of pile installation technology on environment (in scores). 2. a multi-criteria assessment was performed and it was found that a rational geopile installation technology is the use of an open-ended hollow steel pipe using geosynthetic material. the use of this technology provides minimal restrictions to installation possibilities, and the installed piles have good filtration and mechanical properties. 3. the most economical way for installation of one meter geopile is the use of deep vibrator technology. however, this technology can rarely be applied in lithuania and the installed piles eventually lose their filtering properties. 4. the highest load-bearing capacity is obtained in geopiles that are fitted with a closed-ended hollow steel pipe using geosynthetic material technology. however, this technology generates high vibrations that can spread very far through the fluid layers of the soil, thus undermining the foundations and stability of the surrounding structures. fig. 4 schedule of alternate utility degrees conclusions 1 according to the survey questionnaire data, the ranking order of the assessment criteria is as follows: installation cost (eur), load-bearing capacity (in scores), mechanization level of the installation technology (in scores), pile installation possibilities (in scores), duration of pile installation (in scores), impact of pile installation technology on environment (in scores). a1 – driving a hollow steel pipe into the ground using a deep vibrator and using geosynthetic material to reinforce soils; a2 – driving a closed end hollow steel pipe into the ground and using geosynthetic material to reinforce soils; a3 – driving an open-ended hollow steel pipe into the ground and using geosynthetic material to reinforce soils 125 journal of sustainable architecture and civil engineering 2020/2/27 2 a multi-criteria assessment was performed and it was found that a rational geopile installation technology is the use of an open-ended hollow steel pipe using geosynthetic material. the use of this technology provides minimal restrictions to installation possibilities, and the installed piles have good filtration and mechanical properties. 3 the most economical way for installation of one meter geopile is the use of deep vibrator technology. however, this technology can rarely be applied in lithuania and the installed piles eventually lose their filtering properties. 4 the highest load-bearing capacity is obtained in geopiles that are fitted with a closed-ended hollow steel pipe using geosynthetic material technology. however, this technology generates high vibrations that can spread very far through the fluid layers of the soil, thus undermining the foundations and stability of the surrounding structures. referencesk.s. ng, s.a.tan. design and analyses of floating stone columns. soils and foundations 2014;54(3):478-487. https://doi.org/10.1016/j.sandf.2014.04.013 a. k. das, k. deb. modeling of uniformly loaded circular raft resting on stone column-improved ground. soils and foundations 2014;54(6):1212-1224.https:// doi.org/10.1016/j.sandf.2014.11.014 k.s. ng, s.a.tan. simplified homogenization method in stone column designs. soils and foundations 2015;55(1):154-165.https://doi.org/10.1016/j. sandf.2014.12.012 k.s. ng, t. m. tung. coupled discrete-continuum method for studying load-deformation of a stone column reinforces rail track embankments. procedia engineering 2016;142:139-145.https://doi.org/10.1016/j.proeng.2016.02.024 sližytė, d., medzvieckas, j., mackevičius, r. pamatai ir pagrindai: vadovėlis. vilnius: technika, 2012, 241 p. isbn 978-609-457-176-3. simanavičienė r., cibulskaitė j. sprendimo, gauto topsis metodu, patikimumo analizė. lithuanian journal of statistics. 2015, vol54, no 1:110-118. podvezko v., podviezko a. naujos absoliutaus daugiakriterio vertinimo galimybės. liatuvos matematikos rinkinys. lmd darbai. 2013, b54:.54-59.https://doi. org/10.15388/lmr.b.2013.11 tandel y.k., solanki c.h. desai. a.k laboratory experimental analysis. on encapsulated stone column. archives of civil engineering, lix, 3, 2013.https://doi. org/10.2478/ace-2013-0020 pivarč j. stone columns determination of the soil improvement factor. slovak journal of civil engineering vol. xix, 2011, no. 3, 17 21,https://doi. org/10.2478/v10189-011-0014-z sarvaiya h. k., solanki c. h. a study on effects of geosynthetic encasement on floating stone column international journal of civil engineering and technology volume 8, issue 1, january 2017, pp. 891-899. http://www.iaeme.com/ijciet/index.asp herve a. the kendall rank correlation coefficient. 2007.https://personal.utdallas.edu/~herve/abdi-kendallcorrelation2007-pretty.pdf ginevičius r., podvezko v. assesing the accuracy of expert methods. 2004. about the authors vytenis girčys master at faculty of civil engineering and architecture main research area civil engineering address studentu str. 48, lt-51367 kaunas, lithuania e-mail: vyteni.gircys@gmail.com mindaugas daukšys dr. at faculty of civil engineering and architecture main research area civil engineering, construction technology address studentu str. 48, lt-51367 kaunas, lithuania tel. +370 37 300473 e-mail: mindaugas.dauksys@ktu.lt svajūnas juočiūnas lecturer at faculty of civil engineering and architecture main research area civil engineering, construction technology address studentu str. 48, lt-51367 kaunas, lithuania e-mail: svajunas.juociunas@ktu.lt this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 5 journal of sustainable architecture and civil engineering 2020/2/27 *corresponding author: etousi@uniwa.gr brownfield management in greece. the case of piraeus received 2020 01 26 accepted after revision 2020 08 23 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 5-15 doi 10.5755/j01.sace. 27.2.25175 brownfield management in greece. the case of piraeus jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.25175 tousi evgenia* dr.architect-urban and regional planner ntua, adjunct lecturer, university of west attica, department of interior architecture serraos konstantinos professor, national technical university of athens, school of architecture the article presents the contemporary condition in greece as far as brownfield management is concerned. the analysis of the key-obstacles is illustrated through the case of piraeus. research includes literature review and field work. major piraeus’ brownfield sites are classified according to international categorizations. research findings are depicted in thematic maps, using as key-categories the former use, the current use, the system of ownership, the presense of monuments of industrial architectural heritage, the presence of archaealogical sites. this cartographic depiction functions as a necessary tool for policy making on urban regeneration. the conclusions derived from field work provide useful information for further investigation. the ultimate purpose of the article is to highlight the current challenges and potentialities, making the appropriate connections with the international experience on the field. keywords: brownfields, urban regeneration, de-industrialization, greece. the issue of brownfield management has been attracting scientific interest since the 90s in many countries around the world. strongly associated with the stages of the capitalistic system, brownfields have usually a central role in urban planning policies (nebojša, 2015). definitions offered by international literature either focus on environmental damage (epa, 2011; hsrc, 2006) or on dereliction (dixon, 2007 and alker et.al., 2000). the scale of brownfield sites varies widely, from small storage facilities to factories, abandoned military bases, former quarries, sites of former extractive activities and so on. these differences on the scale of the site combined with the variety of former uses have led to methodological problems. moreover, market driven limitations hinder further development especialy in cases that are not attractive to private investors (cpre, 2009). another crucial issue is the fact that many countries lack national environmental standards and cohesive legal framework. from this point of view, greece and many other member states of the european union, face multiple challenges on redeveloping brownfield sites, despite the existing european guidelines. for the european union, the first attempt to handle the brownfield issue dates back to the mid-nineties, when programs urban i and ii were implemented ( pérez, et.al., 2015). these programs have been part of the overall socio-economic cohesion policies of the european union as expressed in the single european act of 1987. a few years later the clarinet (contaminated land reintroduction journal of sustainable architecture and civil engineering 2020/2/27 6 methods habilitation network for environmental technologies in europe) action complemented previous policies. however, many member states of the european union follow different procedures on brownfield redevelopment. in particular, in countries like greece, there is a lack of cohesive national framework that is able to incorporate all the different cases of brownfield rehabilitation and reuse. the national legislation on the issue is fragmental characterized by deficiency of sustainable approach. furthermore, there are no cartographic data or other forms of digital information describing the accurate location of brownfield sites. in addition, there is no public institution with specialized jurisdiction on brownfield management. moreover, complex administrative structures and procedures are responsible for delays in implementing environmental legislation (eu,2019). the observation of these problems was the starting point of this research which tries to portray the contemporary situation in greece, focusing on piraeus, as a pilot case study. the selection of piraeus as a case study is associated with the fact that this area hosts one of the major ports in europe. today, piraeus accommodate appropriately one million visitors per year according to oecd report (oecd, 2017). it is the largest cruise port in balkans (ibid). apart form this, it is one of the major terminals for cargo ships after the collaboration between the piraeus port authority (ppa) and the chinese firm cosco. the piraeus port authority, established during the 30s, run multiple facilities as container handling area, car handling area, cruise shipping area, passenger shipping area and ship repair area (chlomoudis, 2015). all these different land uses are located in the central part of the port and the peripheral municipalities that belong to the regional administrative area of piraeus. in 2008, negotiations between the chinese firm cosco and ppa led to a 35-year contract that allows cosco to operate piers ii and iii of piraeus port (van der putten, et.al., 2016). this contract has affected the neighboring land uses, influencing the redevelopment of abandoned brownfield sites. on account of all these, this case study highlights the significance of brownfield reuse in the era of globalization, where urban planning policies are influenced by cross-border collaborations. piraeus port is becoming a prominent case study as a focal point for maritime transportations (soltaniehha et.al., 2014) from this point of view, brownfield management in this area could be considered as a high priority. the main purpose of this research is to stress the importance of this issue, presenting the current challenges and potentialities. the methods used include review of international literature and field work. literature review focuses not only on scientific papers related to the issue but also on the pertinent greek legislation, so as to provide a succinct overview of the legal framework. furthermore, the research has taken into consideration three main types of categorization; brm (brownfield revitalization methodology), cabernet classification and classification based on former use (petrikova, 2012). the aim is to investigate in depth the regional administrative area of piraeus in light of brownfield management. to begin with, brm organizes all brownfield sites into four categories based on the type of site. to the first category, named a, belong abandoned buildings while category b consists of contaminated land with or without buildings. category c comprises under-functioning buildings that have been incorporated into an urban redevelopment program. category d consists of facilities that are currently in use, characterized as suitable for redevelopment. nonetheless, these areas have not been assigned to a statutory urban redevelopment program. on the other hand, cabernet classification focuses on economic parameters, having three major categories. the first category named a-type sites, involves brownfield areas that attract private investors while categories b and c, collect the less appealing brownfields to private investors. to the c-type sites, belong brownfields that have potential for redevelopment only by public funding because of their unfavorable location or their high level of contamination. the last major categorization, takes into account the former use of the site. in view of this approach, all brownfield sites are organized into the following groups (petrikova, 2012): 7 journal of sustainable architecture and civil engineering 2020/2/27 _ former industrial areas _ landfills _ former military facilities abandoned mining facilities abandoned transportation facilities abandoned buildings of all uses abandoned under construction buildings _ former agricultural facilities used for intensive farming. table 1 socio-economic attributes of the participants in the qualitative research (gender and educational level) gender educational level male female other primary school degree secondary degree tertiary degree 13 17 0 3 17 10 on account of all these, the conducted field work in piraeus was necessary so as to gather information for the most important brownfield sites. the criteria for the selection of the depicted brownfield sites were the location and the size of the area they cover. the aim was to organize the pieces of information according to the three previously mentioned methods. the first step was to identify the brownfields within the urban fabric of piraeus, using the official master plan that illustrates the current land uses. following the identification of brownfields, the next step was to gather data regarding the following categories: _ presence of new land uses _ property ownership _ presence of hardcore brownfield sites _ type of old use _ presence of buildings characterized officially as landmarks of industrial architectural heritage _ year of construction (for brownfield sites that include buildings) _ year of dsicontinuance of function (for brownfields that include buildings) these data have been accumulated through queries to official public authorities as the municipality of piraeus and the historic archive of piraeus. moreover, field work involved multiple visits to the brownfield areas and 30 semi-constructed interviews with members of the local community, either residents or people working in the regional administrative area of piraeus. the interviews had been collected during the period 10th of may-30th of june of 2019. the interview guide focused on participants’ perspective on the future redevelopment of the area around the port and the contribution of brownfield sites to the new masterplan. the participants shared different socio-economic attributes (educational level, sector of employment, age and gender) as presented in the tables below. table 2 socio-economic attributes of the participants in the qualitative research, age and years living or/and working in piraeus age (years) years living or/and working in piraeus 20-35 36-45 45-55 55-67 more than 67 1-5 6-15 16-25 more than 25 10 4 6 3 7 6 4 9 11 table 3 socio-economic attributes of the participants in the qualitative research, type of employment type of employment self employed employee retired unemployed student/part time worker 6 5 8 6 5 journal of sustainable architecture and civil engineering 2020/2/27 8 results these participants were chosen using the method of purposeful random sampling so as to increase credibility. the qualitative research was vital so as to comprehend the emerging tedencies among the members of the local community as far as brownfield redevelopment is concerned, taking into account the suggested new land uses around the port. the information gathered from the interviews combined with the cartographic data is able to offer useful evidence so as to outline the major key-obstacles that hinder sustainable urban development. brief overview of the greek legislation on brownfields and the case of piraeus research results follow three directions, as presented in the following chapters. first and foremost, the analysis of the pertinent legal framework, reveals the fragmentary character of the current legislation, while the description of the physiognomy of brownfield land in an area of strategic interest as piraeus, portrays the significance of the issue. finally, the classification of brownfields in piraeus according to the three international methods, provides a well documented approach, organizing and categorizing different cases of brownfield land. research findings are illustrated in thematic maps as the first step of an overall cartographic depiction of brownfields at local and regional level. these maps could function as a useful tool so as to monitor future development in the area, by recording all new land uses located on former brownfield sites. moreover, mapping of different variables affecting brownfield areas could offer a well rounded perspective on the contemporary problems and conflicts that urban planning should resolve. research also presents local community’s concerns on the new patterns of urban development around piraeus port owed to the presence of foreign investors. according to the environmental implementation review of the european union (2017), greece faces numerous challenges in the field of environmental protection (eu, 2019). one major issue is associated with the closure of illegal landfills combined with the treatment of hazardous wastes. another target regards the implementation of the urban waste water treatment directive of the eu. based on eu’s review, greece should establish an efficient national environmental protection system, able to raise awareness. in addition, it is necessary to create the right incentives for sustainable investments. at national level, the environmental specifications for cleaning contaminated land are described in chapter 7 of the law κυα 24944/1159/06. despite the fact that allusion has been made in a variety of statutory acts, there is no specialized legal framework regarding soil protection. standards for relative field studies are presented in law κυα 24944/1159/2006. various scattered excerpts concerning brownfields are found in laws referring to soil and water protection as presented in the following table (table 4). this fragmental legal framework is considered as one of the key-obstacles that hinder further development. apart from the above mentioned laws, it is important to summarize the legislation referring to former military facilities, as presented in the table (table 5). former military facilities are considered to be important brownfield sites, able to redevelop for the benefit of the local communities. such brownfields could be found in the urban agglomeration of metropolitan areas as in the case of thessaloniki. it is important to mention that the concept of “strategic investment” was introduced in the greek legislation with the law n3894/2010. this law focused on the exploitation of public property. these strategic investments are inaugurating the new era of transnational collaborations. these collaborations often conclude to the construction of flagship projects located in areas of strategic interest. piraeus offers opportunities for redevelopment because of the presence of brownfield sites. in particular, the zone around the port attracts private local and foreign investors, especially the last ten years. as for the legal framework influencing brownfield management in piraeus, besides the above mentioned, the “attica regulatory plan” of 2014 and the local general urban plan play a predominant role. on the one hand “attica regulatory plan” highlights the supralocal significance of piraeus port and on the other local urban plan defines land uses and facilities. on account of the fact that the new 9 journal of sustainable architecture and civil engineering 2020/2/27 table 4 greek legislation related to brownfield land, authors’ categorization regulatory plan emphasizes on limiting urban sprawl (kaltsa, 2015), brownfield redevelopment could be perceived as a necessary tool so as to achieve resielience and sustainability in terms of urban planning. moreover, the geopolitical position of the port and the recent cross-border collaborations have altered the land uses around it affecting brownfield areas as well. these new land uses are associated with the new type of development met during the last years because of the thirty-five year lease between the local authorities and the chinese firm cosco. as presented in the next chapter, cruise ship terminals, luxury hotels and related land uses are to be located around the port transforming the character of the existing urban fabric. table 5 greek legislation concerning former military facilities, authors’ categorization law year short description n1650 1986 a general law for environmental protection κυα 26857/553 1988 measures and restrictions for the protection of underground water from polluted substances κυα 80568/4225 1991 methods and restrictions for using silt coming from urban effluent for agricultural purposes κυα 114218 1997 standards for soil waste management κυα 50910/2727 2003 measures and conditions for soil waste management. national and regional management planning. κυα 13588/725 2006 measures and restrictions for dangerous waste complying with the european guideline 91/689/εοκ κυα 24944/1159 2006 replacement of number 19396/1546/1997 ministerial decision approval of general technical standards for hazardous waste management, according to the article 5 (paragraph β) kya 13588/725, complying with european guideline number 91/15 6/ εκ law year short description ν1337 1983 establishment of urban reorganization enterprise (in greek-epa), assignation of former military land property to the local municipalities ν2745 1999 reorganization of former military land-renewal of assigned former military bases/procedure of urban planning and design ν2984 2002 economic resources coming from the exploitation of the military property attributed to the redevelopment of the site ν3883 2010 assignation of military property to public authorities ν4407 2016 article 16: exploitation of abandoned military facilities in the context of strategic planning physiognomy of brownfield land in piraeus since the early antiquity, piraeus port had an important geopolitical position. however, the sequence of historical events had driven the area to desolation and depopulation. the city had been mostly deserted throughout the ottoman occupation of greece. after the liberation of greece from the ottoman regime and the nomination of athens as the new capital, piraeus gradually regained its power and significance, constituting the base for the industrial development of the capital of greece. in the dawn of the 19th century, the area attracted internal migrants journal of sustainable architecture and civil engineering 2020/2/27 10 fig. 6, 7 year of construction and year of discontinuance of function, authors’ work fig. 8, 9 landmark industrial buildings and type of old use, authors’ work that used to work either at the local factories or in the sector of constructions (leontidou,1989). the refugee inflow subsequent to the asia minor catastrophe in 1922, brought more than 40.000 refugees at piraeus port (pentzopoulos,1962). the urban refugee settlements had been constructed outside the boundaries of the urban agglomeration of piraeus in a distance of 3 to 4 kilometers (sarigiannis, 2000). next to them industrial units had been located. under the pressure of the refugee issue, piraeus was gradually forming its industrial physiognomy (see map 6). the period of prosperity covered more than three decades until the late eighties, when the sector of industry experienced an unprecedented downfall (see map 7). until the mid-nineties the majority of factories had stopped functioning, creating large brownfield areas around the port or along the major transportation roads (see map 8). the main type of brownfields, according to the former use, is abandoned industrial facilities but there are also scattered enclaves of derelict buildings in the post-refugee urban neighborhoods of piraeus (see map 9). 11 journal of sustainable architecture and civil engineering 2020/2/27 types of brownfields in piraeus piraeus has many different types of brownfields, varying from vacand buildings, derlict land, abandoned land and buildings (see map 8). the research has focused on the most important brownfields according to their location and the size of the area they cover. among piraeus’ brownfields there are areas that seem to have attributes of hardcore brownfield sites. they are not only abandoned for many decades but also not incorporated into an overall urban renewal program (see map 11). it is important to mention that most of the brownfield sites belong to type a and b, according to cabernet classification but there are also types -c, located far from the port in the peripheral post refugee areas, as depicted in map 12. these c-types include mostly abandoned refugee houses and blocks of flats constructed during the 30s. one key-obstacle is the fact that there are many different stakeholders involved since property ownership varies widely. as shown in map 10, many brownfields belong to private owners, some to the municipality of piraeus and the peripheral municipalities, others to the national bank of greece and to the pubic power corporation s.a. this factor will probably temporize the redevelopment process since it is difficult to achieve consensus among multiple actors. the absence of an overall plan for brownfield redevelopment in areas like piraeus, has led to the implementation of case-by-case strategies. as a result a few brownfields have already been redeveloped and are now hosting new uses, mostly commercial (see map 13). the cost of redevelopment has been in most of the cases covered by private funding. the new master plan, which was the result of recent negotiations among chinese investors and local authorities, suggested new uses for some areas around the port. these uses included among other luxury hotel, shopping mall, cruise ship passenger stations and a floating ship repair dock. this is a typical example of the new era in terms of globalization. however, the central archaeological council (kas) reviewed proposed investments related to its jurisdiction and ordered revisions. in particular, kas consulted that the proposed area for hosting a large cruise-ship passenger station in the south zone of the port, named drapetsona, is not able to accommodate a large mall of 24,000 m2 as well. according to kas this proposal exceeded the carrying capacity of the area. this decision was also associated with the fact that there are remains of the long walls, constructed during the 4th century bc. this area has also archaeological findings of themistocles’ grave, as shown in map 11. on account of all these, brownfields in piraeus are often mixed or near archaeological sites. the lack of cartographic depiction complicates the decision making in such cases with the view not only to preserve elements of cultural heritage but also to recommend new uses. this means that the areas of archaeological interest should be digitally depicted so as to be compared with the geographical location of brownfield sites. this procedure could clarify the borders of each type of area assisting the strategic priority planning. based on the conducted qualitative research, local community supports the creation of an open green space at the large brownfield site of drapetsona rather than commercial or industrial uses. moreover, the majority of the participants expressed skepticism on the possible impact that the new land uses are bound to have. they claim that such new uses may widen the gap between upgraded and degraded areas within the bordrers of the regional administrative area of piraeus. the last ten years the presence of foreign investors alters former balances. new approaches on urban and regional planning are bound to transform the identity of the wider area around the port. because of its geopolitical relevance and position, piraeus has attracted chinese private investors, turning the national port into a major node for the new silk road (van der putten et.al.,2016). recent negotiations have led to the establishment of a chinese key station inside the port of piraeus, linking maritime and land transport routes. this new form of cooperation orders new directions in urban planning that are going to affect the identity of brownfields in the future. however, the reuse of brownfields in piraeus could function as a tool for sustainable urban planning, intensifying socio-spatial cohesion. journal of sustainable architecture and civil engineering 2020/2/27 12 fig. 12, 13 piraeus brownfields according to cabernet classification and new uses, authors’ work fig. 10, 11 property ownership and hardcore brownfield sites in piraeus, authors’ work flagship projects as the luxury hotels might initiate gentrification procedures according to the opinion of the participants. the majority of the participants stressed, though, the significant contribution of the existing brownfield sites to the possible urban regeneration of the area. almost all of them, correlated the existence of brownfields with urban blight, mentioning the urgent need for urban renewal. however, only a few participants (5 women and 3 men) stated clearly that the new land uses might prove beneficial for the local community. nevertheless, they all agreed on the fact that the new land uses around the port, should be chosen in compliance with the needs of the local community. 13 journal of sustainable architecture and civil engineering 2020/2/27 discussion on account of all the previously mentioned, the sense of place has changed dramatically over the past decades. traditional forms of inter-state cooperation have given way to new types of development, with innovative technologies facilitating cross-border collaborations. apart from the old centers of global economy, strategic territories are emerging in cities that are not considered to be global. the municipality of piraeus in greece is a typical example of such development due to the recent opening up of the greek economy to foreign investors. piraeus has been the main port of greece since the 5th century bc and is today one of the largest ports in the eastern mediterranean sea. despite its contemporary geopolitical significance and all the subsequent changes on urban planning strategies, there is a lack of consistent policy concerning brownfield redevelopment. it is important to mention, that piraeus and greece in general, have not even reached the first stage of an international classification, (adams and de souza,2007), involving the encounter between cost and risk management. this means that there is plenty of room for improvement as far as brownfield management is concerned. expanding the discussion on brownfields beyond piraeus and greece, authors have attempted to illustrate the condition of brownfield recording in eu. taking into consideration the presence or absence of digital record, authors have assesed the situation within the borders of the european union. to fullfil this purpose authors have studied a variety of sources and the available relatively recent data as the european commission’s 5th framework program, key action “the city of tomorrow and cultural heritage” and “the scale and nature of european brownfields” (oliver, et.al., 2005). according to these sources there are significant discrepancies among the member states of the european union as far as the recording of brownfield land is concerned. to update the relatively recent data, authors consulted eu’s conference report the“brownfield redevelopment in the eu”, published in 2019. according to this last report, there are still barriers to overcome as the inadequate, conflicting or changing legal frameworks of the member states and the absence of cooperation of public authorities (dg environment, 2019). based on the relatively recent available data, there are countries that have complete data bases like germany, france and poland (olivier, et.al., 2005) as well as countries that do not have any type of digital data for brownfields. in the middle, one is able to find countries that lack systematic recording at national level but offer data bases for specific regions like milan in italy. countries as greece, bulgaria, hungary, slovakia and slovenia, seem to have deficiency of digital data. this issue is rather significant in areas like piraeus where the presence of foreign investors shapes in multiple ways the prevailing urban planning strategies. conclusions focusing on greece, the lack of systematic digital depiction is a major obstacle for further development. in areas like piraeus, the deficiency of cartographic data leads to fragmentary policies. taking into consideration the fact that these brownfields could create an urban network of multiple uses it is vital to suggest a pilot cartographic depiction, able to reveal the exact location of brownfield site, offering also information about ownership status, level of contamination and neighboring land uses. the enforcement of an urban planning program which aims at brownfield redevelopment could protect socio-economic cohesion in such areas. this could also set barriers to market driven policies that ignore citizens΄ needs. another critical factor is associated with the urban blight met in the post refugee urban areas. this situation affects not only the quality of life but also the prices of land in such areas. furthermore, the presence of archaealogical sites near brownfields complicates an already bewildering situation. a beneficial factor, though, for accelerating redevelopment by reducing rehabilitation’s cost is the low level or the absence of soil contamination in most of the cases. undoubtedly, the issue of brownfield redevelopment is strongly associated with urban planning policies and environmental strategies. from this point of view, a sustainable brownfield policy should achieve balance among social, economic and environmental factors so as to avoid gentrijournal of sustainable architecture and civil engineering 2020/2/27 14 references fication (raco, 2007;ponzini,2010 and watson,2009). for this reason, policy makers should take into consideration all the vulnerable groups that are associated with the brownfield areas. moreover, it is vital to keep balance between public and private sector, especially in areas like piraeus that attract foreign investors. this balance may be expressed as a consensus among different stakeholders like the local community, the investors and the state. however, such an effort might be a complicated procedure, since different actors have different perspective on brownfield redevelopment. skepticism on this aspect of the issue is also found in international literature as many scholars claim stakeholder’s theory to craft legal process. using the suggestion “do the right thing” they try to address morality in urban brownfield redevelopment (pointdexter, 1995). taking into consideration all these, one is able to comprehend the complexity of the issue in terms of sustainability. in cases like piraeus, pressures exercised by foreign investors are bound to shape the urban environment in ways other than public benefit. thus, the existence of a strong national legislative framework combined with explicit urban renewal programs may function as a shield against gentrification. to conclude, city’s transformations should not be implemented in ways that either harm the environment or the social cohesion (harvey,2013). from this point of view, brownfield redevelopment could either lead to resilient compact cities or end up to severe gentrification, especialy in cases like piraeus, where abandoned brownfield sites challenge the contemporary socio-spatial cohesion of the city. acknowledgements the authors would like to thank the historic archive of piraeus and the municipality for their valuable support during the research. adams d., de souza c. 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(2005). the scale and nature of european brownfield, https://www.researchgate.net/publication/228789048_ the_scale_and_nature_of_european_brownfield 15 journal of sustainable architecture and civil engineering 2020/2/27 oecd (2017) cruise shipping and urban development. the case of piraeus., case specific policy analysis, international transport forum, available at https://www.itf-oecd.org/sites/default/files/docs/ cruise-shipping-urban-development-piraeus.pdf pentzopoulos,d., (1962) the balkan exchange of minorities and its impact upon greece, mouton and co, paris. pérez a.p., peláez sánchez s., van liedekerke m. (2015) “remediated sites and brownfields success stories in europe”. a report of the european information and observation network’s national reference centres for soil (eionet nrc soil), european commission institute for environment and sustainability, land resources management poindexter g. ( 1995) addressing morality in urban brownfield redevelopment: using stakeholder theory to craft legal process, 15 va. envtl. l.j. 37 http:// heinonline.org/hol/ landingpage?handle=hein.journals/velj15&div=9&id=&pa ge= ponzini d. (2010) “bilbao effects and narrative defects: a critical rearrraisal of an urban rhetoric” working papers of the program “ villes et territoires”, paris,sciences po. , http://blogs.sciences-p o.fr/recherche-villes/, retrived 17/6/2017 raco m. (2007) „building sustainable communities: spatial policy, place imagina-tions and labour mobility in post-war britain“ policy press, bristol. https://doi.org/10.2307/j.ctt9qgpxs sarigiannis g. (2000) athens 1830-2000, symmetria publications, athens (in greek) sassen s. (2005) “the global city: introducing a concept”, brown journ al of world affairs, winter/ spring 2005, volume xi, issue 2. soltaniehha m., peric a, schol b. (2014) the port of piraeus: industrial zone or urban continuity, 5th isocarp congress 2014, available at https://www. academia.edu/8315681/the_port_of_piraeus_industrial_zone_or_urban_continuity van der putten f., montesano f.s., van de ven j., van ham p. (2016) the geopolitical relevance of piraeus and china’s new silk road for southeast europe and turkey, chapter 1 greece: piraeus and the maritime silkroad, p.11-20, the clingendael institute, hague available at https://www.clingendael.org/sites/default/files/ pdfs/report_the%20geopolitical_relevance_of_piraeus_and_china’s_new_silk_road.pdf watson v. (2009) „the planned city sweeps the poor away. urban planning and 21st century urbanization“ progress in planning 72 (2009) 151-193, elsevier, available at http://www.wiego.org/sites/wiego. org/files/publications/files/watson_planned.city_. sweeps.poor_.away_.pdf https://doi.org/10.1016/j. progress.2009.06.002 tousi evgenia dr.architect-urban and regional planner, adjunct academic staff university of west attica, school of applied arts and culture, department of interior architecture main research area sustainable urban and regional planning. address e-mail: etousi@uniwa.gr serraos konstantinos professor national technical university of athens, school of architecture main research area sustainable urban and regional planning. address e-mail: kserraos@arch.n tua.gr about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). journal of sustainable architecture and civil engineering 2020/2/27 40 *corresponding author: m.azizibabani@modares.ac.ir investigating the impact of the prefabrication concept on the design and selection of building components, case study: peripheral walls in mass housing projects received 2020/05/29 accepted after revision 2020/09/29 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 40-52 doi 10.5755/j01.sace.27.2.26389 investigating the impact of the prefabrication concept on the design and selection of building components, case study: peripheral walls in mass housing projects jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.26389 mohammadhossein azizibabani*, khosro daneshjoo department of architecture, faculty of art, tarbiat modares university, tehran, iran saeid saharkhizan department of structural engineering, international institute of earthquake engineering and seismology (iiees), tehran, iran today, prefabrication is considered as one of the concepts of industrialization in response to the growing needs of human societies for development. it is particularly important to address this concept in mass housing projects. the most important goals in adopting the prefabrication approach are to increase construction speed and quality and reduce costs. a review of the literature on prefabrication illustrates the importance of design for manufacturability and design for assembly concepts about components of prefabricated systems. in this regard, this research has been carried out to identify the criteria and indicators for selection of prefabricated peripheral walls and to design a system based on updatable databases to select proper options according to the importance of criteria and indicators in various mass housing projects. the research method is descriptive-analytical. the results indicate the necessity of involving building material suppliers in designing the mentioned system. therefore, it is envisaged to continuously import new material specifications in the form of suggested options by the material suppliers in the system’s database. the criteria and indicators of peripheral wall selection extracted from the literature review of prefabrication and an analytic hierarchy process structure is proposed to obtain the appropriate options considering the importance of criteria and indicators. to determine the scoring criteria for options, on the one hand, the standards set for the technical specifications of materials were discussed and on the other hand, samples including materials and peripheral wall systems were investigated based on the prefabrication criteria. keywords: prefabrication, industrialization, design for manufacturability, design for assembly, analytic hierarchy process. 41 journal of sustainable architecture and civil engineering 2020/2/27 the widespread and increasing need for human societies to develop construction suggests the necessity of employing new building systems and materials and modern construction methods based on these main goals; increasing construction speed as well as reduction of building weights, costs, and environmental effects. in this regard, the concept of industrialization to meet these goals is important. industrialization is considered as a transition from the traditional stages to optimally exploit human resources and raw materials along with maintaining the quality and value of the produced product to meet the needs of the market and economic efficiency so that using modern technologies in a systematic structure leads used resources operate at the best level of efficiency. increasing the speed and quality of construction along with reducing the time and price of the work are the benefits of industrialization (eghbali & hessari, 2013). industrialization, which has to be employed as an effective strategy in the restructuring of the construction system, seeks its objectives with a systematic approach by applying a chain of actions and processes as follows: _ detailed planning and implementation of systematic monitoring of the design and construction process with the help of integrated management. _ application of modern materials and technologies and mass production of building components. _ the stimulation of demand for integration and concentration of consumption market especially in new towns and worn-out urban fabrics. _ the preparation of the building site from urban design and infrastructure power of view. _ promoting industrialization and training skilled workers and experts. _ developing prefabrication systems. investigating the challenges faced with prefabrication methods is particularly important especially in mass housing projects. prefabrication refers to the process of producing components of a system outside the location of its establishment and carrying them to be assembled in the designated place. the earliest examples of prefabricated buildings in the 17th century have been built in the uk as buildings made of wooden panels that were portable and had the capability of disassembly (eghbali & hessari, 2013). today the concept of prefabrication in the construction industry is associated with industrial manufacture and assembly. in this regard, using similar building components is of particular importance to enable mass production in the factories. despite the advantages of prefabrication methods, using them in mass housing projects especially in less developed regions can bring some challenges in architectural design and construction and maintenance of projects (azman, ahamad, majid, & hanafi, 2010; manley, mckell, & rose, 2009). therefore, there are many types of research in different aspects of prefabrication that can be mentioned. goulding et al. (2015) have examined the economic challenges facing prefabricated methods. mao et al. (2013) have examined the technical obstacles and restrictions of prefabricated methods. blismas et al. (2006), as well as arif and rahimian (2012), investigated the benefits of prefabricated methods in their research. taghdiri and ghanbarzade (2015) investigated the benefits of prefabricated compared to conventional construction methods and concluded that various prefabricated benefits have different values, in this regard, better management on improving the quality of precast products has the most value. most of the studies have achieved the conclusion that overcoming challenges facing prefabricated methods is based on the continuous cooperation among all stockholders in the design, assembly, and installation stages of building components (kpmg, 2016). concerning the prefabrication policies in different countries, in china after the emergence of the environmental crisis in the 70s, the central government considered the prefabrication approach as the main strategy to diminish the bad effects of the construction industry on the environment (li et al., 2014; dou et al., 2019). in this regard, the prefabrication building’s codes were published and financial incentives for prefabrication buildings were specified by the government. in the us, the prefabrication introduction journal of sustainable architecture and civil engineering 2020/2/27 42 approach dates back to the 30s. on that decade the production of affordable mobile houses had been industrialized. in the 70s, due to the emergence of the sustainable development theory, prefabrication was considered as one of the main strategies to diminish the bad effects of the building industry on the environment, so in 1976, the us department of housing and urban development established industry standards for prefabrication buildings (wilson, 2012). prefabrication construction in the uk dates back to the years between two world wars, on those years, this approach was developed due to the lack of expert workers and building materials (howes, 2002). after the second world war prefabrication construction was more prevailed due to the needs of fast reconstruction therefore in 1950 about 34% of london’s residential buildings were constructed using prefabrication methods (ibid). in 1965 the uk government developed a five years program to build half a million houses per year, so the prefabricated approach was more prevailed (millins et al., 2006). peripheral walls are the basis of building facades and contain large amounts of finishing works. these components have great impacts on energy waste, so they are important in prefabrication construction. this applied research reviewed the principles and concepts related to industrialization and prefabrication and extracted the goals, criteria, and indicators of achieving them, to determine a structure for the selection of peripheral walls system in the mass housing projects in iran. in this regard, according to the climatic, economic, cultural, and social conditions and level of available facilities and technologies in each region, the importance of derived indicators in determining the type of peripheral walls may be different. therefore, this research provides the necessary basis to design an application that contains the technical specifications of peripheral walls systems with continuous updating capability and providing the possibility of determining the importance of criteria and indicators to introduce suitable alternatives according to project conditions. the research questions are as follows: _ what are the goals and criteria of prefabrication in mass housing projects? _ what are the indicators of peripheral wall selection based on prefabrication goals in mass housing projects? the importance of prefabrication and its related concepts today, it is largely accepted that the industrialization in the construction has uncontested and substantial advantages in comparison with traditional construction. traditional methods of construction may cause the following problems that can be solved by using industrialized construction. _ waste of resources such as; energy, manpower, capital, time, and materials during the design, construction, operation, and demolition cycles of the buildings. _ the lack of comprehensive and effective control of constructions. _ lack of integrity in planning and activities this shows the importance of the prefabrication concept as one of the necessities of industrialized construction. the review of literature on prefabrication and its related concepts shows the importance of standardization in the process of design and production of a prefabricated system’s components. in this regard wuni & shen (2019) believe that standardization leads to diminishing the complexity of the design and the costs of construction, also the design of prefabricated buildings can be diversified by the customization of the component’s production line. standardization in the prefabrication approach brings the possibility of mass production and accelerates the construction (gao et al, 2019).). concerning the advantages of the prefabrication approach in residential projects, kibert (2012) and li et al. (2014) have mentioned some items like (1) fast return on investment for developers (2) costs reduction for residents (3) safe working conditions for construction workers and (4) waste minimization due to the high precision and repeatable production. rod (2015) and steinhardt & manley (2016) believe that it is easier to standardize the components of residential buildings. design for manufacturability (dfm) and design for assembly (dfa) are two bases of the prefabrication concept. dfm is the process of designing parts, components, or products for ease of 43 journal of sustainable architecture and civil engineering 2020/2/27 fig. 1 typical stages in a dfma procedure manufacturing with an end goal of making a better product at a lower cost. this would be possible by simplifying, optimizing, and refining the product design. the following are the requirements and benefits of dfm that should be considered in the design phase of the product: source: (boothroyd, 2005). _ reducing the variation in system’s components _ reducing the time and cost of the production _ simplifying the production methods _ simplifying and standardization where ever possible dfa seeks to simplify the product, so the cost of the assembly process is reduced. dfa also includes a set of measures for combining parts to form the final product. economical and technical justifications of using prefabricated methods in the field of the construction industry depend on technical measures in the architectural design phase (stoll, 1986). therefore, the assembly of the manufactured components in the building site can be done by the minimum construction operations, which causes accurate implementation, higher speed, and lower costs, so the desired goals will be more accessible (riba, 2013). dfm and dfa concepts should always be considered simultaneously in the prefabricated projects so the concept of design for manufacturability and assembly (dfma) has emerged in the literature of prefabrication (bogue, 2012). the primary studies on dfa date back to the research of boothroyd and dewhurst (1987) which resulted in the extraction of actions during the design stages to achieve the optimal results in the assembly of the components. the main point in the design stage is to reduce the number of components types to reduce the probability of errors in the assembly stage. every part of a prefabricated system must be in coordination with other parts during the normal operation of the system and also should be separable from other components (emmatty & sarmah 2012). dfm related studies are also concerned with finding materials and methods of producing prefabricated system’s components with a reduction in production costs, and ease of assembly (ibid). both issues are highly important in prefabricated projects and this indicates the necessity of addressing the concept of design for manufacturability and assembly (dfma). dfma consists of stages shown in fig 1.the benefits and guidelines of dfma are presented in table 1. journal of sustainable architecture and civil engineering 2020/2/27 44 table 1 general dfma guidelines and their benefits guidelinesbenefits minimize the part count improved reliability, reduced purchasing and inventory costs, simplified assembly use standard, off-the-shelf parts rather than custom components reduced costs, lower purchasing lead times, potentially greater reliability minimize and standardize the use of fasteners/ design for efficient joining and fastening reduced costs, simplified assembly, improved reliability, simplified repair and maintenance use as few dissimilar materials as possiblesimplified jointing, fewer manufacturing processes minimize the use of fragile parts cost reductions due to fewer part failures, easier handling and assembly do not over-specify tolerances or surface finisheasier manufacture and reduced fabrication costs design for ease of fabrication cost reductions from the elimination of complex fixtures and tooling consider modular designsreduced costs due to simplified assembly and test aim for mistake-proof designs cost reductions by eliminating need to re-work incorrectly assembled parts design for simple part orientation and handling cost reductions due to non-valueadded manual effort or dedicated fixturing design with predetermined assembly technique in mind cost reductions from use of proven/ known techniques consider design for automated/ robotic assemblypotential cost reduction over manual methods prefabrication approach in peripheral walls today, buildings use about 40% of the total global energy consumption (attmann, 2010). the external envelope system of the building which non-load-bearing peripheral walls are of its main components is a significant contributor to the corresponding energy demand and indoor comfort conditions. non-load-bearing walls generally can be classified from the aspects of function, position in the structure, and the type of materials. these components have significant impacts on the building energy performance and its related costs and also the thermal and acoustic comfort of the occupants. earthquake data in different parts of the world show the importance of the seismic performance of these walls and the necessity of their coordination with the whole structure (noorifard.et.al, 2016). according to the concepts of dfm and dfa, in the case of the possibility of defining a factory production line for the components of a wall, and predicting the necessary preparations to assemble the components at the construction site, the prefabricated concept can be allocated to the system (gao.et.al, 2019). however, the use of any material with these conditions can not necessarily lead to the achievement of the intended goals for prefabrication. most studies have stated that the main objectives of using prefabricated systems are to increase the quality and speed and reduce the cost of construction (eghbali & hessari, 2013; gao.et.al, 2019; bogue, 2012; emmatty & sarmah, 2012; kibert, 2012; li et. al, 2014). quality includes a wide range of aspects from aesthetical to functional, which according to the purpose of this study, it is important to measure the quality in the proposed ranking system, so source: (bogue, 2012). 45 journal of sustainable architecture and civil engineering 2020/2/27 table 2 non-load-bearing walls classification n on -l oa dbe ar in g (n on st ru ct ur al ) w al ls f u nc ti o n peripheral walls fig. 2. walls classification base on function shared walls with neighbors with interior shared spaces partition walls p o si ti o n in t he s tr u ct u re infill walls fig. 3. infill wall 6 non-loadbearing (nonstructural) walls shared walls with neighbors figure 2: walls classification base on function with interior shared spaces partition walls position in the structure infill walls figure 3: infill wall partition wall type of materials discrete walls made of blocks continues walls made of panels these components have significant impacts on the building energy performance and its related costs and also the thermal and acoustic comfort of the occupants. earthquake data in different parts of the world show the importance of the seismic performance of these walls and the necessity of their coordination with the whole structure (noorifard.et.al, 2016). according to the concepts of dfm and dfa, in the case of the possibility of defining a factory production line for the components of a wall, and predicting the necessary preparations to assemble the components at the construction site, the prefabricated concept can be allocated to the system (gao.et.al, 2019). however, the use of any material with these conditions can not necessarily lead to the achievement of the intended goals for prefabrication. most studies have stated that the main objectives of using prefabricated systems are to increase the quality and speed and reduce the cost of construction (eghbali & hessari, 2013; gao.et.al, 2019; bogue, 2012; emmatty & sarmah, 2012; kibert, 2012; li et. al, 2014). quality includes a wide range of aspects from aesthetical to functional, which according to the purpose of this study, it is important to measure the quality in the proposed ranking system, so the criterion for evaluation of measurable qualities are national or international standards and codes. in this framework the following factors and their evaluation criteria are important in the selection of peripheral walls in a prefabricated system:  fire resistance (inbc: part 3; isiri:12055-1)  energy performance (inbc: part 19)  acoustic performance (inbc: part 18; iso717-1)  the possibility of industrial production (inbc: part 11)  seismic performance (inbc: part 6) partition wall ty pe o f m at er ia ls discrete walls made of blocks continues walls made of panels the criterion for evaluation of measurable qualities are national or international standards and codes. in this framework the following factors and their evaluation criteria are important in the selection of peripheral walls in a prefabricated system: _ fire resistance (inbc: part 3; isiri:12055-1) _ energy performance (inbc: part 19) _ acoustic performance (inbc: part 18; iso717-1) _ the possibility of industrial production (inbc: part 11) _ seismic performance (inbc: part 6) _ other indicators: durability, maintenance and transportation costs, environmental impacts the ability to recycle materials, and so on. (expert questionnaire) the criteria and indicators in fig. 4 are considered as the decision-making basis in the selection of the peripheral walls in a prefabricated system. the method of content analysis based on the literature review was deployed to extract the indicators of the three main criteria of prefabrication. in this regard, an analytic hierarchy process (ahp) method can be used to compare the proposed options and choose the preferred option based on the importance of criteria and indicators under the structure in fig. 5. source: authors. journal of sustainable architecture and civil engineering 2020/2/27 46 fig. 5 the hierarchical structure of comparing the proposed options in determining the type of peripheral walls the require ments of the proposed ranking system 7 § other indicators: durability, maintenance and transportation costs, environmental impacts the ability to recycle materials, and so on. (expert questionnaire) the criteria and indicators in figure 4 are considered as the decision-making basis in the selection of the peripheral walls in a prefabricated system. the method of content analysis based on the literature review was deployed to extract the indicators of the three main criteria of prefabrication. in this regard, an analytic hierarchy process (ahp) method can be used to compare the proposed options and choose the preferred option based on the importance of criteria and indicators under the structure in figure 5. figure 4. criteria and indicators of the selection of the peripheral walls in the framework of prefabrication figure 5. the hierarchical structure of comparing the proposed options in determining the type of peripheral walls 7 § other indicators: durability, maintenance and transportation costs, environmental impacts the ability to recycle materials, and so on. (expert questionnaire) the criteria and indicators in figure 4 are considered as the decision-making basis in the selection of the peripheral walls in a prefabricated system. the method of content analysis based on the literature review was deployed to extract the indicators of the three main criteria of prefabrication. in this regard, an analytic hierarchy process (ahp) method can be used to compare the proposed options and choose the preferred option based on the importance of criteria and indicators under the structure in figure 5. figure 4. criteria and indicators of the selection of the peripheral walls in the framework of prefabrication figure 5. the hierarchical structure of comparing the proposed options in determining the type of peripheral walls fig. 4 criteria and indicators of the selection of the peripheral walls in the framework of prefabrication based on the criteria of the prefabricated approach, the proposed ranking system should include the following requirements for selecting superior choices about the peripheral walls. _ the possibility of determining the importance of different levels of criteria and applying changes in their values based on situations and desired goals. _ the possibility of loading different proposed options and introduce their technical specifications to enrich the data bank of the system. _ determining the maximum and minimum scores on quantities and qualities of the technical specifications of each option based on available standards. therefore, the following workflow is being proposed for the ranking system. the proposed system should be available for all stockholders to select the proper option about the peripheral walls by determining the value of criteria and indicators of prefabrication based on the features of their projects. the procedure is as follows: the manufacturer of the product, after obtaining the necessary quality approvals, submit a request for registration of materials in the proposed ranking system data7  other indicators: durability, maintenance and transportation costs, environmental impacts the ability to recycle materials, and so on. (expert questionnaire) the criteria and indicators in figure 4 are considered as the decision-making basis in the selection of the peripheral walls in a prefabricated system. the method of content analysis based on the literature review was deployed to extract the indicators of the three main criteria of prefabrication. in this regard, an analytic hierarchy process (ahp) method can be used to compare the proposed options and choose the preferred option based on the importance of criteria and indicators under the structure in figure 5. figure 5. the hierarchical structure of comparing the proposed options in determining the type of peripheral walls 47 journal of sustainable architecture and civil engineering 2020/2/27 fig. 6 the workflow of the proposed system of ranking investigation of the common samples base. after confirming the technical specifications based on the inquiry from the certification authorities (road, housing and urban development research center of iran), regarding the indicators for which there is a quantitative national or international standards, the system offers a point to each index by comparing technical specifications with other materials in the database. to determine the score of indicators which require experimental vision, technical specifications of materials with a questionnaire based on comparison with some of the basic materials that are addressed in the samples, are being referred to the group of system’s partner specialist. therefore, all the materials in the system database are ranked in terms of quality and technical specifications, and it will be possible to introduce samples that are compatible with the value set for the selection criteria, based on the ahp selection process. this part of the study deals with the samples which include the common materials of the prefabricated peripheral walls. the requirements for entering any new option in the proposed ranking system are to pass quality tests and obtain approvals related to the road, housing, and urban development research center of iran. therefore, the qualitative evaluation of materials is done according to the approved technical specifications and comparison with the relevant standards. regarding indicators for which there are no specific standards, the sources of evaluation are interviews with experts, including civil engineers and architects involved in construction projects. the purpose of the investigation of the samples is to achieve a scale to determine the score of different qualitative aspects of the proposed materials. it is more important about indicators for which no specific standards have been set. therefore, it has been tried that samples include a wide range of common materials in the iranian construction market in terms of qualitative characteristics, technical specifications, methods of assembly, unit size, and price. findings 8 the requirements of the proposed ranking system based on the criteria of the prefabricated approach, the proposed ranking system should include the following requirements for selecting superior choices about the peripheral walls.  the possibility of determining the importance of different levels of criteria and applying changes in their values based on situations and desired goals.  the possibility of loading different proposed options and introduce their technical specifications to enrich the data bank of the system.  determining the maximum and minimum scores on quantities and qualities of the technical specifications of each option based on available standards. therefore, the following workflow is being proposed for the ranking system. figure 6. the workflow of the proposed system of ranking. source: authors the proposed system should be available for all stockholders to select the proper option about the peripheral walls by determining the value of criteria and indicators of prefabrication based on the features of their projects. the procedure is as follows: the manufacturer of the product, after obtaining the necessary quality approvals, submit a request for registration of materials in the proposed ranking system database. after confirming the technical specifications based on the inquiry from the certification authorities (road, housing and urban development research center of iran), regarding the indicators for which there is a quantitative national or international standards, the system offers a point to each index by comparing technical specifications with other materials in the database. to determine the score of indicators which require experimental vision, technical specifications of materials with a questionnaire based on comparison with some of the basic materials that are addressed in the samples, are being referred to the group of system’s partner specialist. therefore, all the materials in the system database are ranked in terms of quality and technical specifications, and it will be possible to introduce samples that are compatible with the value set for the selection criteria, based on the ahp selection process. investigation of the common samples source: authors. the investigation of samples aimed to achieve a suitable scale to determine the weights of the indicators in the ahp process for the selection of the peripheral walls system. the literature review shows the importance of three criteria of construction speed, costs, and quality in the prefabrication approach which include the mentioned indicators in table 4. to adapt the different conditions existed for building projects, the importance of criteria and resulting indicators may be different and this affects the selection of systems for the building components. in the following table, the proposed domain of scores is given to indicators that can be the main source of the decision making regarding the selection of the peripheral walls. these scores are determined based on the necessities of national building codes and standards and expert questionnaire. journal of sustainable architecture and civil engineering 2020/2/27 48 sa m pl e ti tle description advantages disadvantages related images l ig ht w ei gh t p er lit e bl oc ks these blocks are produced using mineral or artificial material as coarse material and cement base materials as a sticky one. the important advantages of these blocks can be attributed to their thermal insulation properties, which in some regions of iran provide the requirements of the national codes without the need for additional layers. the most important disadvantages of this option can be pointed out to the multiplicity of the later stages (finishing work), high water uptake and ultimately slow execution rates. _ thermal and acoustic insulation _ low weight _ fire resistant _ needs to later stages _ assembly speed _ high amount of mortar and plaster _ recyclability _ high disposal value fig. 7. lightweight perlite blocks 9 this part of the study deals with the samples which include the common materials of the prefabricated peripheral walls. the requirements for entering any new option in the proposed ranking system are to pass quality tests and obtain approvals related to the road, housing, and urban development research center of iran. therefore, the qualitative evaluation of materials is done according to the approved technical specifications and comparison with the relevant standards. regarding indicators for which there are no specific standards, the sources of evaluation are interviews with experts, including civil engineers and architects involved in construction projects. the purpose of the investigation of the samples is to achieve a scale to determine the score of different qualitative aspects of the proposed materials. it is more important about indicators for which no specific standards have been set. therefore, it has been tried that samples include a wide range of common materials in the iranian construction market in terms of qualitative characteristics, technical specifications, methods of assembly, unit size, and price. table 3: descriptive and analytic features of samples sample title description advantages dis advantages related images lightweigh t perlite blocks these blocks are produced using mineral or artificial material as coarse material and cement base materials as a sticky one. the important advantages of these blocks can be attributed to their thermal insulation properties, which in some regions of iran provide the requirements of the national codes without the need for additional layers. the most important disadvantages of this option can be pointed out to the multiplicity of the later stages (finishing work), high water uptake and ultimately slow execution rates. thermal and acoustic insulation low weight fire resistant needs to later stages assembly speed high amount of mortar and plaster recyclability high disposal value figure 7: lightweight perlite blocks. source: authors autoclaved aerated concrete (aac) blocks these blocks are made of a specific type of porous light concrete, which is mainly made of silica, cement, and lime. this product consists of two main processes; forming porosity in grout (a mixture of cement, lime, and silica powder) and curing. sticky materials (mainly cement and lime) react in an autoclave with silica materials and give hydrated calcium silicate. these blocks are fire resistant with low thermal conductivity. the use of these materials leads to a nodiffusion of the flame (bastani & ilani, 2011). aac blocks are insulated against sound and heat due to their low special weight, so it is not necessary to use additional insulation layers and this can reduce the cost of construction and prevent waste of capital. high compressive strength thermal and acoustic insulation low weight fire resistant needs to later stages assembly speed high amount of mortar and plaster recyclability high disposal value figure 8: the thermal resistant comparison between aac blocks wall and other walls. source (bastani & ilani, 2011) source: authors. a ut oc la ve d ae ra te d co nc re te (a a c) b lo ck s these blocks are made of a specific type of porous light concrete, which is mainly made of silica, cement, and lime. this product consists of two main processes; forming porosity in grout (a mixture of cement, lime, and silica powder) and curing. sticky materials (mainly cement and lime) react in an autoclave with silica materials and give hydrated calcium silicate. these blocks are fire resistant with low thermal conductivity. the use of these materials leads to a nodiffusion of the flame (bastani & ilani, 2011). aac blocks are insulated against sound and heat due to their low special weight, so it is not necessary to use additional insulation layers and this can reduce the cost of construction and prevent waste of capital. _ high compressive strength _ thermal and acoustic insulation _ low weight _ fire resistant _ needs to later stages _ assembly speed _ high amount of mortar and plaster _ recyclability _ high disposal value fig. 8. the thermal resistant comparison between aac blocks wall and other walls 9 this part of the study deals with the samples which include the common materials of the prefabricated peripheral walls. the requirements for entering any new option in the proposed ranking system are to pass quality tests and obtain approvals related to the road, housing, and urban development research center of iran. therefore, the qualitative evaluation of materials is done according to the approved technical specifications and comparison with the relevant standards. regarding indicators for which there are no specific standards, the sources of evaluation are interviews with experts, including civil engineers and architects involved in construction projects. the purpose of the investigation of the samples is to achieve a scale to determine the score of different qualitative aspects of the proposed materials. it is more important about indicators for which no specific standards have been set. therefore, it has been tried that samples include a wide range of common materials in the iranian construction market in terms of qualitative characteristics, technical specifications, methods of assembly, unit size, and price. table 3: descriptive and analytic features of samples sample title description advantages dis advantages related images lightweigh t perlite blocks these blocks are produced using mineral or artificial material as coarse material and cement base materials as a sticky one. the important advantages of these blocks can be attributed to their thermal insulation properties, which in some regions of iran provide the requirements of the national codes without the need for additional layers. the most important disadvantages of this option can be pointed out to the multiplicity of the later stages (finishing work), high water uptake and ultimately slow execution rates. thermal and acoustic insulation low weight fire resistant needs to later stages assembly speed high amount of mortar and plaster recyclability high disposal value figure 7: lightweight perlite blocks. source: authors autoclaved aerated concrete (aac) blocks these blocks are made of a specific type of porous light concrete, which is mainly made of silica, cement, and lime. this product consists of two main processes; forming porosity in grout (a mixture of cement, lime, and silica powder) and curing. sticky materials (mainly cement and lime) react in an autoclave with silica materials and give hydrated calcium silicate. these blocks are fire resistant with low thermal conductivity. the use of these materials leads to a nodiffusion of the flame (bastani & ilani, 2011). aac blocks are insulated against sound and heat due to their low special weight, so it is not necessary to use additional insulation layers and this can reduce the cost of construction and prevent waste of capital. high compressive strength thermal and acoustic insulation low weight fire resistant needs to later stages assembly speed high amount of mortar and plaster recyclability high disposal value figure 8: the thermal resistant comparison between aac blocks wall and other walls. source (bastani & ilani, 2011) source: (bastani & ilani, 2011). h a ya t w al l p an el s the middle layer of these panels is made of polystyrene foam which is a product of the petrochemical industry and is composed of small crystals that expand under pressure and vapor. the side layers of these panels are attached to the center using special lace, which increases the strength and adhesion between the layers. the outer layers of these panels are made of lightweight concrete with special properties such as thermal and sound insulation, frostbite resistance, and a reduction of damage caused by the earthquake. _ low weight _ thermal and acoustic insulation _ low amount of debris _ fire resistant _ assembly speed _ recyclability _ high disposal value fig. 9. details of hayat wall panels 10 sample title description advantages dis advantages related images hayat wall panels the middle layer of these panels is made of polystyrene foam which is a product of the petrochemical industry and is composed of small crystals that expand under pressure and vapor. the side layers of these panels are attached to the center using special lace, which increases the strength and adhesion between the layers. the outer layers of these panels are made of lightweight concrete with special properties such as thermal and sound insulation, frostbite resistance, and a reduction of damage caused by the earthquake. low weight thermal and acoustic insulation low amount of debris fire resistant assembly speed recyclability high disposal value figure 9: details of hayat wall panels 3d panels with concrete cover these panels have an intermediate core of polystyrene or polyurethane, and two layers of steel mesh are placed on either side. after the installation, the sides of these panels would be sprayed by concrete. assembly speed low amount of debris thermal and acoustic insulation needs to later stages recyclability high disposal value high weight fire resistant high amount of mortar and plaster figure 10: details of a 3d panel easywall light weight panels these panels are made of fiber cement board for the panel facings with an interior composite core material of lightweight concrete mix made from ordinary portland cement, additives, aggregates, admixtures and expanded polystyrene assembly speed no plaster needs thermal and acoustic insulation fire resistant low amount of debris resistance to lateral forces recyclability figure 11: easywall detail. source: authors table 3 descriptive and analytic features of samples 49 journal of sustainable architecture and civil engineering 2020/2/27 sa m pl e ti tle description advantages disadvantages related images 3d p an el s w it h co nc re te c ov er these panels have an intermediate core of polystyrene or polyurethane, and two layers of steel mesh are placed on either side. after the installation, the sides of these panels would be sprayed by concrete. _ assembly speed _ low amount of debris _ thermal and acoustic insulation _ needs to later stages _ recyclability _ high disposal value _ high weight _ fire resistant _ high amount of mortar and plaster fig. 10. details of a 3d panel 10 sample title description advantages dis advantages related images hayat wall panels the middle layer of these panels is made of polystyrene foam which is a product of the petrochemical industry and is composed of small crystals that expand under pressure and vapor. the side layers of these panels are attached to the center using special lace, which increases the strength and adhesion between the layers. the outer layers of these panels are made of lightweight concrete with special properties such as thermal and sound insulation, frostbite resistance, and a reduction of damage caused by the earthquake. low weight thermal and acoustic insulation low amount of debris fire resistant assembly speed recyclability high disposal value figure 9: details of hayat wall panels 3d panels with concrete cover these panels have an intermediate core of polystyrene or polyurethane, and two layers of steel mesh are placed on either side. after the installation, the sides of these panels would be sprayed by concrete. assembly speed low amount of debris thermal and acoustic insulation needs to later stages recyclability high disposal value high weight fire resistant high amount of mortar and plaster figure 10: details of a 3d panel easywall light weight panels these panels are made of fiber cement board for the panel facings with an interior composite core material of lightweight concrete mix made from ordinary portland cement, additives, aggregates, admixtures and expanded polystyrene assembly speed no plaster needs thermal and acoustic insulation fire resistant low amount of debris resistance to lateral forces recyclability figure 11: easywall detail. source: authors e a s yw a l l l ig ht w ei g ht p an el s these panels are made of fiber cement board for the panel facings with an interior composite core material of lightweight concrete mix made from ordinary portland cement, additives, aggregates, admixtures and expanded polystyrene _ assembly speed _ no plaster needs _ thermal and acoustic insulation _ fire resistant _ low amount of debris _ resistance to lateral forces _ recyclability fig. 11. easywall detail 10 sample title description advantages dis advantages related images hayat wall panels the middle layer of these panels is made of polystyrene foam which is a product of the petrochemical industry and is composed of small crystals that expand under pressure and vapor. the side layers of these panels are attached to the center using special lace, which increases the strength and adhesion between the layers. the outer layers of these panels are made of lightweight concrete with special properties such as thermal and sound insulation, frostbite resistance, and a reduction of damage caused by the earthquake. low weight thermal and acoustic insulation low amount of debris fire resistant assembly speed recyclability high disposal value figure 9: details of hayat wall panels 3d panels with concrete cover these panels have an intermediate core of polystyrene or polyurethane, and two layers of steel mesh are placed on either side. after the installation, the sides of these panels would be sprayed by concrete. assembly speed low amount of debris thermal and acoustic insulation needs to later stages recyclability high disposal value high weight fire resistant high amount of mortar and plaster figure 10: details of a 3d panel easywall light weight panels these panels are made of fiber cement board for the panel facings with an interior composite core material of lightweight concrete mix made from ordinary portland cement, additives, aggregates, admixtures and expanded polystyrene assembly speed no plaster needs thermal and acoustic insulation fire resistant low amount of debris resistance to lateral forces recyclability figure 11: easywall detail. source: authors source: authors. e u r o p a n e l s ys te m these panels consist of two galvanized steel that the space between them is filled with high-density polystyrene (20 kg/m3) inside a special device and form an integrated panel. these panels are produced in two forms (normal and special) based on the position of the studs. _ assembly speed _ resistance to lateral forces _ thermal and acoustic insulation _ low amount of debris _ low weight _ fire resistant _ high amount of mortar and plaster _ recyclability fig. 12. section of the europanel 11 sample title description advantages dis advantages related images europanel system these panels consist of two galvanized steel that the space between them is filled with high-density polystyrene (20 kg/m3) inside a special device and form an integrated panel. these panels are produced in two forms (normal and special) based on the position of the studs. assembly speed resistance to lateral forces thermal and acoustic insulation low amount of debris low weight fire resistant high amount of mortar and plaster recyclability figure 12: section of the europanel. source: authors findings the investigation of samples aimed to achieve a suitable scale to determine the weights of the indicators in the ahp process for the selection of the peripheral walls system. the literature review shows the importance of three criteria of construction speed, costs, and quality in the prefabrication approach which include the mentioned indicators in table 4. to adapt the different conditions existed for building projects, the importance of criteria and resulting indicators may be different and this affects the selection of systems for the building components. in the following table, the proposed domain of scores is given to indicators that can be the main source of the decisionmaking regarding the selection of the peripheral walls. these scores are determined based on the necessities of national building codes and standards and expert questionnaire. table 4. determining the scores of the indicators of prefabrication for peripheral walls in residential use. criteria indicators assigned scores for ahp process score reference 0,1 2,3 4,5 construction speed need for later stages high (finishing and hard works) moderate (finishing works) low expert questionnaire amount of wet working high moderate low assembly speed (m2/day) 10-29 30-59 60 and upper costs unit price (m2) the scores are determined based on the minimum and maximum price of materials in the data bank list price of the current year disposal value (%) 10 and upper 5-9 1-4 expert questionnaire need for insulation sound and thermal insulation sound or thermal insulation no need inbc (part 18 & 19); isiri: 8568-3, 11058, 8621 quality compressive strength (kg/cm2) 10-19 20-39 40 and upper inbc (part 6) weight of every square meter of the wall (kg/ m2) 120 and upper 50-119 less than 50 source: authors. journal of sustainable architecture and civil engineering 2020/2/27 50 criteria indicators assigned scores for ahp process score reference 0,1 2,3 4,5 c on st ru ct io n s pe ed need for later stages high (finishing and hard works) moderate (finishing works) low expert questionnaire amount of wet working high moderate low assembly speed (m2/day) 10-29 30-59 60 and upper c o st s unit price (m2) the scores are determined based on the minimum and maximum price of materials in the data bank list price of the current year disposal value (%) 10 and upper 5-9 1-4 expert questionnaire need for insulation sound and thermal insulation sound or thermal insulation no need inbc (part 18 & 19); isiri: 8568-3, 11058, 8621 q u al it y compressive strength (kg/cm2) 10-19 20-39 40 and upper inbc (part 6) weight of every square meter of the wall (kg/ m2) 120 and upper 50-119 less than 50 resistance to lateral forces (kg/cm2) 20-40 40-60 60 and upper service life (year) 10-19 20-39 40 and upper expert questionnaire thermal resistance (m2.k/w) less than 1 1-2 more than 2 inbc (part 19) recyclability (%) 10-39 40-79 80 and upper expert questionnaire disposal value (%) 10 and upper 5-9 1-4 expert questionnaire fire – resistance (minute) 60-179 180-239 240 and upper inbc (part 3) amount of debris in case of destruction high (winning parts) moderate (nonwinning parts) low (nonwinning parts) expert questionnaire weighted sound reduction index (rw) 30-39 40-49 50 and upper inbc (part 18) table 4 determining the scores of the indicators of prefabrication for peripheral walls in residential use. the review of theoretical foundations and literature shows that the prefabrication approach as one of the basic requirements of industrialization contains three main criteria; quality, construction speed, and reduction of costs. based on the prefabrication literature if necessary arrangements for industrial manufacturing and assembly of different components of the building were forecasted, the prefabrication concept would be assigned to the manufacturing process of each component of the system and consequently the whole construction system theoretically. however, an investigation of the peripheral wall samples shows that if the components of the system are larger, lighter, and needless of finishing or mortar to be assembled, it is practically more in line with the nature of prefabrication concept. the importance of prefabrication criteria may be different due to the conclusion 51 journal of sustainable architecture and civil engineering 2020/2/27 project type, scale, financial resources, the place of the construction site, and so on. the existence of a wide range of different materials and systems based on the prefabricated approach in many cases, especially mass housing projects, has made the optimal selection for project participants a complex matter. this indicates the necessity of the development of a systematic order of the selection of materials and methods of construction and the various components of prefabricated systems based on the importance of prefabrication criteria. in this research, the conceptual design of this system regarding the selection of peripheral walls in the form of an updatable database is presented. due to the possibility of differences in the value of criteria related to prefabrication, a selection approach based on ahp has been adopted in the system. it is possible to generalize this system to the other components of the building in future research. referencesarif, m., goulding, j., & rahimian, f. p. promoting off-site construction: future challenges and opportunities. journal of architectural engineering, 2012; 18(2): 75-87.https://doi.org/10.1061/(asce) ae.1943-5568.0000081 attmann, o. green architecture: advanced technologies and materials, new york: mcgraw hill; 2010 azman, m., ahamad, m., majid, t., & 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housing policy in the uk. palgrave.2006.https://doi.org/10.1007/9780-230-80268-1 noorifard a, mehdizadeh saradj f, vafamehr m. conceptual assessment of seismic performance of nonstructural walls in conventional medium rise buildings according to the experiences of past earthquakes. bsnt. 2016; 6 (3) :38-50. riba. riba plan of work 2013 designing for manufacture and assembly. london: royal institute of british architects (riba); 2013. rod, s. why sweden beats the world hands down on prefab housing. the chartered institute of building; 2015. steinhardt, d. a., & manley, k. adoption of prefabricated housing-the role of country context. sustainable cities and society, 2016; 22, 126-135.https:// doi.org/10.1016/j.scs.2016.02.008 stoll, h. w. design for manufacture: an owerwiew. applied mechanics reviews, 1986; 39(9), 1356. https://doi.org/10.1115/1.3149526 taghdiri, a., & ghanbarzade, s. advantages of prefabrication construction in comparison with conventional construction. armanshahr architecture & urban development journal, 2016; 8 (15): 18-25. wilson, b. an examination of electricity consumption patterns in manufactured housing units. housing policy debate. 2012: 22(2), 175-199. https://doi. org/10.1080/10511482.2011.648204 wuni, i. y., & shen, g. q. critical success factors for modular integrated construction projects: a review. building research & information, 2019. https://doi. org/10. 1080/09613218.2019.1669009. about the authors mohammadhossein azizibabani ph.d. student architecture, department of architecture, faculty of art, tarbiat modares university, tehran, iran main research area affordable housing design, sustainable design. address faculty of art, tarbiat modares university, tehran, iran tel. +989120929844 e-mail: m.azizibabani@modares.ac.ir khosro daneshjoo assistant professor the department of architecture, faculty of art, tarbiat modares university, tehran, iran main research area technical architecture, architectural structures. address faculty of art, tarbiat modares university, tehran, iran tel. +982182883753 e-mail: khdaneshjoo@modares.ac.ir saeid saharkhizan ph.d. student earthquake engineering and seismology, international institute of earthquake engineering and seismology, tehran, iran main research area structural engineering. address tel. +989127188946 e-mail: saeid.saharkhizan@stu.iiees.ac.ir this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 67 reinforcement corrosion degree effect on adhesion with concrete andrius kielė, vitoldas vaitkevičius, vytautas sasnauskas, danutė vaičiukynienė*, rėda bistrickaitė kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. *corresponding author: danute.palubinskaite@ktu.lt http://dx.doi.org/10.5755/j01.sace.7.2.6871 a number of aggressive substances influence reinforced concrete building structures’ decay and corrosion processes. in this research work the influence of steel reinforcement corrosion degree on its adhesion to concrete strength characteristics was determined. two 14 mm diameter reinforcement steel types: ribbed (bst500s) and smooth (a240c) were used in the work. the mass loss of steel reinforcement due to the corrosion was calculated. after the explosion in different solutions: 10 % of nacl, hcl and nh4no3 the weight of steel reinforcement with smooth surface decreases for 1-8 %, while the mass loss of ribbed reinforcement was 2–13 % in comparison with control of steel reinforcement samples, which exposure in water. it was found that both smooth and ribbed steel reinforcement influenced by nh4no3 solution corroded more intensively. the adhesion of this type of reinforcement (influenced by nh4no3 solution) to the concrete was the lowest: the adhesion of smooth steel reinforcement decreased till 76 % compared to the control concrete specimens adhesion and ribbed steel reinforcement was 92 %. the unaffected steel reinforcement samples adhesion to concrete was the highest (46.33 kn and 59.875 kn, this is corresponds 100 %).the potentiometric measurements showed that the most favorable probability of steel reinforcement corrosion to perform is when the steel reinforcement is exposed to nh4no3 solution, potential difference is < -350 mv. keywords: reinforcement, concrete, corrosion degree. 1. introduction metals’ corrosion is usually defined as degradation of the properties as a result of chemical and electrochemical reaction with environment. corrosion is a self-contained conversion of metals into raw ores (ohtsu et al., 2011). the different damages are experienced because of metal corrosion; this problem is relevant for manufacturing production processes (elgarf,1997). reinforced concrete is a widely used building material. the use of steel reinforcement in concrete structures provides more strength and maintains required shape and dimensions of the material, but a number of aggressive substances can affect reinforced concrete building structures’ decay and corrosion processes (yoon et al., 2000). the influence of carbonates, sulfates, chlorides and frost-thaw cycles are the main reasons of reinforced concrete structures deterioration. the carbonation processes occurring in concrete structures absorbing co2 and moisture, decrease concrete ph and determine corrosion processes in steel reinforcement concrete (shima et al., 1999, vidal et al., 2007, zhang et al., 2010). when the reinforced concrete structures are influenced by sulphates, the former new crystalline structures in concrete significantly increase its volume and this is resulted by various sizes of gaps and cracks (novak, et al., 2001; kanakubo et al., 2008; kayyali and yeomans, 1995). the chlorides operating in steel reinforcement concrete, destroys oxidized iron passive layer and further the oxidation processes take place intensively. so, it is necessary to protect reinforced concrete structures from the aggressive effects of aqueous solutions, because water is the catalyst of chemical reactions of aggressive components in alkaline concrete environment (alonso et al., 1998; imperatore and rinaldi, 2009; kurahashi and oshita, 2009, 2004; o’brien corporation, 2004, alonso et al., 1998). mechanical strength of steel reinforcement and concrete adhesion depends on the surface of the reinforcement, physical-mechanical properties of concrete, load direction, stress state, and other factors. the measurement methods of reinforced concrete qualitative corrosion process, determining the corrosion process and intensity are classified into: a) visual inspection of the reinforced concrete structure determining the uniformity of corrosion, the nature and the color of corrosion products, their adhesion with metal, etc.; b) the assessment of the environment, where the reinforced concrete structure corrosion processes take place, i.e., the nature of the sediments, turbidity, etc.; darnioji architektūra ir statyba 2014. no. 2(7) journal of sustainable architecture and civil engineering issn 2029–9990 68 c) the use of indicators for cathode and anodic areas distribution on the surface of reinforced concrete structures which allows to determine the solution color change. the weight method is the main quantitative reinforced concrete construction corrosion process determination method. the thickness of corrosive steel reinforcement layer is directly proportional to the sample mass change when corrosion in reinforced concrete structures has continuous and even nature. corrosion rate k is expressed by the sample mass change per surface area and time unit (eq. 1) (vidal et al., 2007): reinforcement corrosion degree effect on adhesion with concrete andrius kielė 1 , vitoldas vaitkevičius 1 , vytautas sasnauskas 1 , danutė vaičiukynienė 1* , rėda bistrickaitė 1 kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania *corresponding author: danute.palubinskaite@ktu.lt a number of aggressive substances influence reinforced concrete building structures’ decay and corrosion processes. in this research work the influence of steel reinforcement corrosion degree on its adhesion to concrete strength characteristics was determined. two 14 mm diameter reinforcement steel types: ribbed (bst500s) and smooth (a240c) were used in the work. the mass loss of steel reinforcement due to the corrosion was calculated. after the explosion in different solutions: 10% of nacl, hcl and nh 4 no 3 the weight of steel reinforcement with smooth surface decreases for 1-8%, while the mass loss of ribbed reinforcement was 2-13% in comparison with control of steel reinforcement samples, which exposure in water. it was found that both smooth and ribbed steel reinforcement influenced by nh 4 no 3 solution corroded more intensively. the adhesion of this type of reinforcement (influenced by nh 4 no 3 solution) to the concrete was the lowest: the adhesion of smooth steel reinforcement decreased till 76% compared to the control concrete specimens adhesion and ribbed steel reinforcement was 92%. the unaffected steel reinforcement samples adhesion to concrete was the highest (46.33 kn and 59.875 kn, this is corresponds 100%).the potentiometric measurements showed that the most favorable probability of steel reinforcement corrosion to perform is when the steel reinforcement is exposed to nh 4 no 3 solution, potential difference is < -350 mv. keywords – reinforcement, concrete, corrosion degree 1. introduction metals’ corrosion is usually defined as degradation of the properties as a result of chemical and electrochemical reaction with environment. corrosion is a self-contained conversion of metals into raw ores (ohtsu et al. 2011). the different damages are experienced because of metal corrosion; this problem is relevant for manufacturing production processes (elgarf 1997). reinforced concrete is a widely used building material. the use of steel reinforcement in concrete structures provides more strength and maintains required shape and dimensions of the material, but a number of aggressive substances can affect reinforced concrete building structures’ decay and corrosion processes (yoon et al. 2000). the influence of carbonates, sulfates, chlorides and frost-thaw cycles are the main reasons of reinforced concrete structures deterioration. the carbonation processes occurring in concrete structures absorbing co 2 and moisture, decrease concrete ph and determine corrosion processes in steel reinforcement concrete (shima et al. 1999, vidal et al. 2007, zhang et al. 2010). when the reinforced concrete structures are influenced by sulphates, the former new crystalline structures in concrete significantly increase its volume and this is resulted by various sizes of gaps and cracks (novak et al. 2001, kanakubo et al. 2008, kayyali and yeomans 1995). the chlorides operating in steel reinforcement concrete, destroys oxidized iron passive layer and further the oxidation processes take place intensively. so, it is necessary to protect reinforced concrete structures from the aggressive effects of aqueous solutions, because water is the catalyst of chemical reactions of aggressive components in alkaline concrete environment (alonso et al. 1998, imperatore and rinaldi 2009, kurahashi and oshita 2009, 2004 o’brien corporation 2004, alonso et al. 1998). mechanical strength of steel reinforcement and concrete adhesion depends on the surface of the reinforcement, physical-mechanical properties of concrete, load direction, stress state, and other factors. the measurement methods of reinforced concrete qualitative corrosion process, determining the corrosion process and intensity are classified into: a) visual inspection of the reinforced concrete structure determining the uniformity of corrosion, the nature and the color of corrosion products, their adhesion with metal, etc.; b) the assessment of the environment, where the reinforced concrete structure corrosion processes take place, i.e., the nature of the sediments, turbidity, etc.; c) the use of indicators for cathode and anodic areas distribution on the surface of reinforced concrete structures which allows to determine the solution color change. the weight method is the main quantitative reinforced concrete construction corrosion process determination method. the thickness of corrosive steel reinforcement layer is directly proportional to the sample mass change when corrosion in reinforced concrete structures has continuous and even nature. corrosion rate k is expressed by the sample mass change per surface area and time unit (eq. 1) (vidal et al. 2007): k m s = ⋅ δ τ (1) where: δm is the mass change, s is the area; τ is time. the necessary large number of samples is the disadvantage of steel reinforcement corrosion weight method, as one sample gives only one point of ”corrosion rate − time” dependency. ; (1) where: δm is the mass change, s is the area; t is time. the necessary large number of samples is the disadvantage of steel reinforcement corrosion weight method, as one sample gives only one point of ”corrosion rate time” dependency. the released or absorbed gas volume during corrosion is measured using volume method for the detection of steel reinforcement corrosion degree. hydrogen is released during steel reinforcement corrosion processes and hydrogendepolarization. oxygen is absorbed if corrosion processes take place in an oxygenated depolarization. corrosion meter determines hydrogen volume during corrosion. corrosive steel reinforcement weight is calculated according to the reaction equation when gas volume is known. the volume method evaluates corrosion process kinetics of an individual sample. however, this method is more complicated and is not accurate when corrosion takes place with mixed oxygen–hydrogen depolarization. the purpose of this scientific research work was to determine the influence of steel reinforcement corrosion degree on its adhesion to concrete and concrete’s strength characteristics. 2. materials and methods two 14 mm diameter reinforcement steel types: ribbed (bst500s) and smooth (a240c) were used in the work. their chemical composition is given in table 1. each reinforcement type was grouped into five groups with three 125 mm long bars. each group was exposed by different solutions: ▪ group 1 was the control group; it was stored under normal (laboratory)conditions; ▪ group 2 had water impact; ▪ group 3 had 10 % of nacl solution impact; ▪ group 4 had 10 % of hcl solution impact; ▪ group 5 had 10 % of nh4no3 solution impact. all steel reinforcement groups were exposed for six months. reinforcing steel respectively corroded and the appropriate layer of rust were formed on the surface. steel exposed to ammonium nitrate solution corroded most of all. the composition of steel corrosion products was determined by xrd analysis. corrosion product analysis was determined by diffractometer dron – 6. note: cuka radiation, ni filter, the detector movement step was 0.02 °, the intensity of the measurement time step was 0.5 s, and tube voltage was 30 kv, the current was 20 ma. after six months of the exposure in different environments, all types of steel reinforcement samples were embedded in 100x100x100mm size concrete cubes. portland cement cem i 42.5 n (ma) lst en 1971 (the specific surface was 310 m2/kg, setting start was 150 min, the early strength after 2 days was 24.3 mpa, and the standard strength after 28 days was 57.4 mpa) was used. the composition of the concrete was estimated and c20/25 class samples (table 2) were formed. corroded steel reinforcement was embedded in concrete cube center, in an upright position with overhanging 25 mm bar from the cube (fig. 1). concrete samples were stored in water for 28 days in order to reach the standard strength. steel reinforcement from concrete cubes was pushed out after 28 days. the force required to push out the reinforcement from concrete cube, i.e., the force of steel reinforcement adhesion with concrete, was fixed. table 2. composition of 1m3 of concrete c 20/25 materials the amount of 1m3 of concrete mixture, kg portland cement 280.0 kg water 166 kg coarse aggregate (gravel) 4/16 mm fraction 1010.0kg fine aggregate (sand) 0/4 mm fraction 850.0 kg superplasticizer, muraplast fk 63.3“ 1.4 kg water-cement ratio w/c = 0.59 density of the concrete ρb =2306 kg/m3 tonitechnik 2020.0600/132/02 computerized press was used for measuring the strength of concrete specimens and deformations. measurement range was 0 ... 600 kn; measurement rate was 0 ... 1.0 n/mm2×s, load rate was (0.6 ± 0.4) mpa/s. the device elcometer 331 was used to measure the probability of reinforcement corrosion in concrete. copper sulphate electrode was used for potentiometric measurements. reinforcement corrosion probability was defined when the potential value between the reinforcement bar in concrete and the standard electrode was used. table 1. chemical composition of used reinforcements reinforcement steel mark chemical composition, % c 100 si 100 mn 100 p 1000 s 1000 cr 100 ni 100 cu 100 mo 1000 v 1000 n2 1000 ceq 100 n 1000 ti 1000 b 1000 as 1000 bst500s 17 20 57 12 32 7 12 26 9 3 9 30 a240c 18 8 54 11 44 2 2 2 7 5 0,8 5 69 fig. 1. concrete samples with embedded steel reinforcement after the crushing test 3. results and discussion formed on the sample the surface of reinforcement, rust were selected from the smooth and ribbed steel reinforcement groups of samples, which were affected by nacl, hcl, and nh4no3 solutions. the rust layer was negligible on the other concrete samples that were exposed to h2o and controls. according to the xrd it was determined that sodium chloride crystals, iron oxide and iron oxide hydrates dominated in the corrosion products after the steel reinforcement sample treatment by nacl solution (fig. 2). after six months, according to xrd, crystallized ferric chloride dominated in steel reinforcement corrosion products of smooth reinforcement samples exposed to hcl (fig. 3). akagenite (ferric chloride, version) and traces of quartz (fig. 3, a) were detected on ribbed bars near the dominant crystallized ferric chloride. nh4no3 prevailed in rust of smooth and ribbed steel reinforcement samples, affected by nh4no3 solution. traces of ni(no3)2(nh3)6 were detected in rust of smooth reinforcement. sio2 and feo(oh)2 compounds were find in the corrosion products of ribbed steel reinforcement samples treated with nh4no3. steel reinforcement samples were weighed before and after corrosion test in order to evaluate the degree of corrosion more exactly. determinated weight losses are presented in column diagrams (fig. 5). the greatest weight losses for corroded smooth and ribbed steel reinforcement fig. 2. xrd of smooth (a) and ribbed (b) reinforcements affected by 10% of nacl aqueous solution a b a b fig. 3. xrd of smooth (a) and ribbed (b) reinforcements affected by 10% of hcl aqueous solution 70 were detected for the samples treated with nh4no3 solution. the lowest corrosion degree of steel reinforcement samples were for that samples which held in the air and affect with water (groups i and ii). the corrosion rate (kl) of steel reinforcement was calculated according to the formula (eq. 2) (astm g1-03 1999): a b fig. 4. xrd of smooth (a) and ribbed (b) reinforcements affected by 10% of nh 4 no 3 aqueous solution after six months, according to xrd, crystallized ferric chloride dominated in steel reinforcement corrosion products of smooth reinforcement samples exposed to hcl (fig. 3). akagenite (ferric chloride, version) and traces of quartz (fig. 3, a) were detected on ribbed bars near the dominant crystallized ferric chloride. nh 4 no 3 prevailed in rust of smooth and ribbed steel reinforcement samples, affected by nh 4 no 3 solution. traces of ni(no 3 ) 2 (nh 3 ) 6 were detected in rust of smooth reinforcement. sio 2 and feo(oh) 2 compounds were find in the corrosion products of ribbed steel reinforcement samples treated with nh 4 no 3 . steel reinforcement samples were weighed before and after corrosion test in order to evaluate the degree of corrosion more exactly. determinated weight losses are presented in column diagrams (fig. 5). the greatest weight losses for corroded smooth and ribbed steel reinforcement were detected for the samples treated with nh 4 no 3 solution. the lowest corrosion degree of steel reinforcement samples were for that samples which held in the air and affect with water (groups i and ii). the corrosion rate (kl) of steel reinforcement was calculated according to the formula (eq. 2) (astm g1-03 1999): , mm / year; (2) where: k is the coefficient, k = 8.76·e4; w is weight loss, g; s is the damaged surface area, cm 2 ; h – reinforcement length, cm; h = 12.5 cm; d – metal density, g/cm 3 ; d = 7.85 g/cm 3 ; t – testing time, val.; t = 1.5 year = 13140 h. steel reinforcement corrosion degree of testing samples on the next stage was calculated according to the given formula no 2, and the results are presented in table 3. the maximum corrosion rate was in the samples of group 5, the minimal was in group 1 of steel corrosion samples. steel reinforcement corrosion weight loss products are presented in fig. 5. deformation curves of the steel reinforcement samples were determinate as well. steel reinforcement was squeezed and concrete cube crashed after the overloading of the steel reinforcement samples by compressive load. sample deformation and load dependence is curved, the deviation from the straight line increases with increasing load and stress. concrete test cubes were loaded with a constant load. the test data are presented in fig. 6. a b fig. 5. steel corrosion weight loss of smooth (a) and ribbed (b) reinforcement after 6 months tds wk kl ⋅⋅ ⋅ = hrrs ⋅⋅⋅+⋅⋅= ππ 22 2 table 3. determination of corrosion degree reinforcement types corrosion degree, mm/year ribbed smooth group 1. 0 0 group 2. 0.0257 0.0125 group 3. 0.0521 0.0320 group 4. 0.0827 0.0653 group 5. 0.1626 0.0980 , mm / year; (2) where: k is the coefficient, k = 8.76·e4; w is weight loss, g; s is the damaged surface area, cm2; hrrs ⋅⋅⋅+⋅⋅= ππ 22 2 h – reinforcement length, cm; h = 12.5 cm; d – metal density, g/cm3; d = 7.85 g/cm3; t – testing time, val.; t = 1.5 year = 13140 h. steel reinforcement corrosion degree of testing samples on the next stage was calculated according to the given formula no 2, and the results are presented in table 3. the maximum corrosion rate was in the samples of group 5, the minimal was in group 1 of steel corrosion samples. steel reinforcement corrosion weight loss products are presented in fig. 5. a b fig. 4. xrd of smooth (a) and ribbed (b) reinforcements affected by 10% of nh4no3 aqueous solution table 3. determination of corrosion degree reinforcement types corrosion degree, mm/year ribbed smooth group 1. 0 0 group 2. 0.0257 0.0125 group 3. 0.0521 0.0320 group 4. 0.0827 0.0653 group 5. 0.1626 0.0980 deformation curves of the steel reinforcement samples were determinate as well. steel reinforcement was squeezed and concrete cube crashed after the overloading of the steel reinforcement samples by compressive load. sample deformation and load dependence is curved, the deviation from the straight line increases with increasing load and stress. concrete test cubes were loaded with a constant load. the test data are presented in fig. 6. the minimum force of steel reinforcement adhesion to the concrete was set in the samples of group 5. ribbed steel reinforcement adhesion force of this group decreased by 92 %, and smooth reinforcement decrease was 76 % in comparison to the control samples (group 1) adherence force. fig. 5. steel corrosion weight loss of smooth (a) and ribbed (b) reinforcement after 6 months a b 71 fig. 6. the relative force changes of steel reinforcement adhesion with concrete the reinforced concrete samples corrosion conditions predictions dependence on the corrosion time was determined using a copper/copper sulfate electrode (table 5). direct potentiometry (zhang et al., 2010) was measured on eight test points as shown in test scheme (fig. 7). table 5. corrosion criteria in steel reinforcement concrete samples, using a variety of standard electrodes (according to astm c876-91) copper/copper sulfate electrode; measured potential, mv corrosion conditions > -200 slight (10 % probability of corrosion) -200...-350 the medium < -350 high (> 90 % probability of corrosion) <-500 particularly expected the potential jump, called the electrode potential is formed during electrode and solution contact. metal cations’ transition from the solid phase to liquid or liquid to the solid is the reason of its appearance. the appeared negative charge electrostatically attracts metal cations passed to the solution that are located at the metal negative surface. fig. 7. corrosion potential measurement scheme: 1–8 points of measurement, 9 – reinforcement, thickness 14 mm, 10 – reinforced concrete cube the potentiometric measurements showed that the most favorable probability for corrosion is in group 5, where the steel reinforcement was exposed to nh4no3 solution. the potential difference is equal to -350 mv. however, the corrosion rate is likely to decrease in time (fig. 8). fig. 8. corrosion conditions prediction dependence on the corrosion time using copper/copper sulfate electrode in steel reinforcement concrete samples 72 the lowest probability for corrosion is in the group 3, where the steel reinforcement was exposed by nacl solution, and the potential difference was > -200 mv. 4. conclusions 1. the mass loss of steel reinforcement due to the corrosion was calculated. after the explosion in different solutions: 10 % of nacl, hcl and nh4no3 the weight of steel reinforcement with smooth surface decreases for 1–8 %, while the mass loss of ribbed reinforcement was 2–13 % in comparison with control of steel reinforcement samples, which exposure in water. 2. the xrd analysis of all the samples showed that sodium chloride nacl dominate in the samples of the steel reinforcement corrosion products in group 3; ferric chloride crystallized fecl2 × 4h2o in group 4, and ammonium nitrate nh4no3 in group 5. 3. it was found that both smooth and ribbed steel reinforcement influenced by nh4no3 solution corroded more intensively. the adhesion of this type of reinforcement (influenced by nh4no3 solution) to the concrete was the lowest: the adhesion of smooth steel reinforcement decreased till 76 % compared to the control concrete specimens adhesion and ribbed steel reinforcement was 92 %. the unaffected steel reinforcement samples adhesion to concrete was the highest (46.33 kn and 59.875 kn, this is corresponds 100 %). 4. the potentiometric measurements showed that the most favorable probability of steel reinforcement corrosion to perform is when the steel reinforcement is exposed to nh4no3 solution, potential difference is < -350 mv. acknowledgements this work has been supported by the european social fund within the project “development and application of innovative research methods and solutions for traffic structures, vehicles and their flows”, project code vp1-3.1šmm-08-k-01-020. references standard practice for preparing, cleaning and evaluating corrosion test specimens. astm g1-03 (1999). alonso c., andrade c., rodriguez j., diez j. m. 1998. factors controlling cracking of concrete affected by reinforcement corrosion. materials and structures, 31(7), 435–441. http://dx.doi.org/10.1007/bf02480466 elgarf m. s. 1997. mangat bond characteristics of corroding reinforcement in concrete beams. materials and structures, 32, 89–97. imperatore s., rinaldi z. 2009. mechanical behaviour of corroded rebars and influence on the structural response of r/c elements. concrete repair, rehabilitation and retrofitting ii, 489–495. yoon s., wang k., weiss w. j., shah s. p. 2000. interaction between loading, corrosion, and serviceability of reinforced concrete. aci materials journal, 97 (6), 637–644. kanakubo t., oyado m., saito y. 2008. study on local bond behaviour between corroded reinforcement and concrete. the 3rd acf international conference, 1146–1152. kayyali o. a., yeomans s. r. 1995. bond and slip of coated reinforcement in concrete. construction and buildings material, 9(4), 219–226. kurahashi t., oshita h. 2009. shape determination of 3-d reinforcement corrosion in concrete based on observed temperature on concrete surface. computers and concrete, 1(7), 63–81. novak p., mala r., joska l. 2001. influence of pre-rusting on steel corrosion in concrete. cement and concrete research, 31(4), 589–593. http://dx.doi.org/10.1016/s0008-8846(01)00459-8 ohtsu m., mori k., kawasaki y. 2011. corrosion process and mechanisms of corrosion-induced cracks in reinforced concrete identified by ae analysis. strain, 47(s2), 179–186. http://dx.doi.org/10.1111/j.1475-1305.2010.00754.x shima h., chou l., okamura h. 1999. micro and macro models for bond in reinforced concrete. journal of the faculty of engineering, 39 (2). 133–194 vidal t., castel a., françois r. 2007. corrosion process and structural performance of a 17 year old reinforced concrete beam stored in chloride environment. cement and concrete research, 37(11), 1551–1561. http://dx.doi.org/10.1016/j.cemconres.2007.08.004 zhang r., castel a., françois r. 2010. concrete cover cracking with reinforcement corrosion of rc beam during chlorideinduced corrosion process. cement and concrete research, 40(3), 415–425. http://dx.doi.org/10.1016/j.cemconres.2009.09.026 2004 o’brien corporation. test repot study of 6n hcl corrosion on commercial 316 ss, hastelloy c-22 and true tube variants. april 2004. received 2014 04 22 accepted after revision 2014 05 28 vitoldas vaitkevičius – associate professor at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. main research area: ultra high performance concrete, high strength concrete, secondary raw materials, concrete additives. address kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu str. 48, lt-51367. tel.: +370 37 300465 e-mail: vitoldas.vaitkevicius@ktu.lt 73 andrius kielė – master at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. main research area: special-purpose cement concretes, concrete additives. address: kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu str. 48, lt-51367. tel.: +370 37 300465 e-mail: andrius.kiele@gmail.com vytautas sasnauskas – associate professor at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. main research area: natural zeolites, cement supplementary materials. address: kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu str. 48, lt-51367. tel.: +370 37 300465 e-mail: vytautas.sasnauskas@ktu.lt danutė vaičiukynienė –professor at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. main research area: synthesis of zeolites, zeolite modification and their sorption properties, use of zeolite in cement and concrete systems, special-purpose cement systems. address: kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu str. 48, lt-51367. tel.: +370 37 300465 e-mail: danute.palubinskaite@ktu.lt rėda bistrickaitė – lecturer at kaunas university of technology, faculty of civil engineering and architecture, department of building structures. main research area: research of concrete and reinforced concrete innovative structures, mechanics of layered structures, new composite materials. address: kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu str. 48, lt-51367. tel.: +370 37 300465 e-mail: reda.bistrickaite@ktu.lt journal of sustainable architecture and civil engineering 2020/2/27 16 *corresponding author: pelkkim@uamont.edu architect familiarity and perceptions surrounding sustainable design, leed, and engineered wood products in arkansasreceived 2020/01/17 accepted after revision 2020/09/16 journal of sustainable architecture and civil engineering vol. 2 / no. 27 / 2020 pp. 16-31 doi 10.5755/j01.sace.27.2.25104 architect familiarity and perceptions surrounding sustainable design, leed, and engineered wood products in arkansas jsace 2/27 http://dx.doi.org/10.5755/j01.sace.27.2.25104 gabrielle sherman college of forestry, agriculture and natural resources, university of arkansas at monticello; monticello, ar 71656, usa tamara walkingstick university of arkansas cooperative extension service, university of arkansas division of agriculture, little rock, ar 72204, usa kenneth wallen, matthew pelkki* college of forestry, agriculture and natural resources, university of arkansas at monticello; monticello, ar 71656, usa the sustainable building design movement has gained momentum within the united states in recent years. this has led to a proliferation of green building certification programs like leadership in energy and environmental design (leed) and the development of engineered wood products (ewp) like cross laminated timber (clt). often, architects serve as the conduit between green building construction material and their use in construction. there is need to investigate the perceptions and practices of architects on the topic of green building certification and ewps. in partnership with the american institute of architects (aia), this study surveyed registered architects practicing in arkansas to a) examine interest in and application of leed certification and b) beliefs related to sustainability, affordability, and availability of ewps. results suggest a majority of architects surveyed have interest in the leed program and have previously earned leedcertification for a building design. respondents rated the importance of improving human health and wellbeing as especially high but appear to doubt the ability of ewp to contribute to sustainable design. analysis revealed that clt use is significantly lower than that of more typical ewps such as plywood panels and glue laminated timber. architects also indicated that the affordability and availability of modern ewp represent significant barriers to their utilization within the state. to increase the rate of sustainable development, it will be necessary to highlight benefits to human and environmental health and generate interest amongst architectural clientele. keywords: cross laminated timber, building design, green building certification, mass timbers. 17 journal of sustainable architecture and civil engineering 2020/2/27 sustainability is a hallmark of community planning and development, and public policy, with human-environmental benefits possible through conscientious, environmentally-friendly design choices (ortiz, castells, and sonnemann 2009). efforts to institutionalize pathways to such choices – e.g., those that guide building construction materials – have led to organizations like the u.s. green building council (usgbc) and the leadership in energy and environmental design (leed) criteria. building construction, in addition to maintenance and operation, account for one-third of global energy use, with roughly 11% of energy sector emissions originating from the construction industry (jain, mital, and syal 2013; un iea 2017). engineered wood products (ewps) offer a structural material alternative to steel and concrete construction that can mitigate energy consumption from buildings. in the case of building construction with ewps or other sustainable materials, the choice to consider or pursue sustainable design and materials is often initialized early in the process by a client or architect. regarding architects, few studies assess this groups familiarity with, use of, and opinions on sustainable design, leed, and ewps, particularly in regions with established forest-products sectors and developing ewp markets. as such, this research examines perceptions of sustainable design, leed certification, and ewps among architects practicing in arkansas. introduction literature review of contextual and conceptual foundations leed certification and sustainability goals the leed certification systems is a widely recognized and implemented framework for green building design and has evolved over the years to accommodate a growing number of environmental concerns (matisoff, noonan, and mazzolini, 2014; amiri, ottelin, and sovari 2019). its criterion of sustainability for both old and new construction is comparable to that of other international green building rating systems, such as the uk-based building research establishment environmental assessment method (breeam) and japan’s comprehensive assessment system for building environmental efficiency (casbee) (ahmed, hasan, and mallick, 2018). whether the evaluation is made through a credit-earning system or benchmark assessment, certification for the majority of green building systems is awarded to construction surpassing some set threshold of ecological efficacy and energy performance (ahmed, hasan, and mallick, 2018). within leed, certification is tiered based on the number of points awarded, with four levels of compliance available: certified, silver, gold, and platinum. earlier iterations tended to emphasize over-simplified denominations of material sustainability based on single-attribute criteria such as recyclability (usgbc 2019a). a review of leed buildings in new york found that only buildings of the gold tier and higher produced statistically significant reductions in energy consumption (scofield 2013). meanwhile, findings surrounding the energy saving potential of occupied leed certified buildings reveal that on average, commercial leed buildings of medium energy use yield energy savings of 19-39% as compared to equivalent non-leed counterparts, depending on factors such as age and climate (newsham, mancini, and birt 2009). however, this trend alone does not fully reveal the reality of energy use in leed buildings, as energy use rates have been found to vary widely amongst individual buildings, and, in fact, 28-35% of leed certified buildings were found to use more energy per unit floor area than non-leed buildings (newsham, mancini, and birt 2009). amiri and others (2019) found that the energy efficiency of buildings with lower levels of leed certification was questionable, especially at the “certified” level. in response to these shortcomings, a new version of the system, known as leed v4, was introduced (scofield 2013). currently, leed specifies six targeted credit categories through which up to 100 certification points are awarded. in total, they include location and transport, sustainable sites, water efficiency, energy and atmosphere, material and resources, and indoor environmental quality (usgbc 2019a). ten additional points, known as innovation and regional priority credits, may be awarded to a project based on its ability to address local, specific environmental concerns (usgbc 2019b). by adhering to leed’s accreditation guidelines and requirements within these journal of sustainable architecture and civil engineering 2020/2/27 18 credit categories, buildings can meet the sustainability goals (usgbc 2019a). sustainability goals, referred to as impact categories, were developed as means of addressing the question of what a leed building should accomplish (usgbc 2019b). in total, there are seven categories, each with its own set of indicators of compliance (table 1). leed v4 impact category description reverse contribution to global climate change reduce co2 emissions associated with building operations, transportation, material use, water consumption, and energy utilization enhance individual human health and well-being improve comfort of building occupants and reduce exposure to harmful element protect and restore water resources promote water conservation and water quality preservation. preserve natural hydrological cycles protect, enhance and restore biodiversity and ecosystem services improve habitat conservation opportunities, ecosystem services, and species diversity on a local and global level promote sustainable and regenerative material resource cycles reduce negative environmental impacts produced by raw material extraction through renewable material life-cycles build a greener economy raise the value of green buildings and support green industries through financial incentives enhance social equity, environmental justice, community health and quality of life create a strong sense of place and resilient living communities. promote human rights and environmental justice table 1 the seven leed impact categories with corresponding descriptions engineered wood products if sustainability is to be given a central position in community planning and development, a potential route to address traditional building design shortcomings is via emergent engineered wood products (ewps). engineered wood products provide performance and cost improvements over traditional sawn lumber (van de lindt et al. 2010). cross-laminated timbers (clt) are a rapidly emerging structural ewps, and is an alternative to steel and concrete, due to their seismic resistance, elasticity, structural strength, and dimensional stability (van de lindt et al. 2010; ritter, skog, and bergman 2011). the environmental benefits of clt include improved use of natural resources, carbon storage, and ecosystem improvement (ritter, skog, and bergman 2011). sustainable design and architect perspectives architects play a key role in the promotion sustainable design frameworks like leed, particularly those that can increase sustainability and the use of forest products that benefit economies and ecosystems (o’connor et al. 2004). furthermore, the fact that leed participation is voluntary on the part of architects and their clientele stresses that from interest, to design, to construction, the success of leed is partially dependent on cognitive and experiential elements like attitudes, interests, experiences, and familiarity. as such, this research builds on the empirical basis of previous assessments of wood-products sector stakeholders and architects (franzini, toivonen, and toppinen 2018; mat’ová and kaputa 2018) alongside a theoretical framework informed by attitude research and volitional behavior, e.g., the theory of planned behavior (tpb) (ajzen 1991; bysheim and nyrud 2009), a conceptualization of direct experience (heberlein 2012), and past work on familiarity (hammitt 1979; peterson and vaske 2017; oku and fukamachi 2006). 19 journal of sustainable architecture and civil engineering 2020/2/27 attitudes attitudes represent an indispensable concept to assess an individual’s positive-to-negative evaluation of a phenomenon, for example, a stakeholder’s evaluation of local timber extraction (allport 1935; eagly and chaiken 2007). in the context of sustainability and wood products, previous studies reveal positive evaluations of and attitude towards leed and ewps among architects, but not necessarily leed among clientele (usgbc 2019b; ross, woxblom, and mccluskey 2010). for example, research conducted on members of the triangle chapter of the usgbc in north carolina show that barriers to sustainable design stem from a reluctance on the part of developers and investors to commit to the initial higher costs of sustainable design, regardless of cost saving features associated with the long-term operation of green building (knowles et al. 2011). in the context of ewps, bysheim and nyrud (2009) found architects’ attitude towards wood as a structural material was a significant predictor of their intention to use wood in construction. these studies and other, stress the importance of understanding attitude towards certain characteristics of sustainable building design and ewps as essential information for these sectors to be successful. for example, gosselin et al. (2017) found architects had a positive attitude towards wood’s characteristic, “ease of use”; in contrast, “fire resistance” was associated with a negative attitude. experience and familiarity regular, direct experience can have a positive effect on intentions and subsequent behavior (heberlein 2012). similarly, familiarity is viewed as an important component of environmental sustainability preference (hammitt 1979). a critical element of the leed and ewps context that is in line with this perspective is that few clt structures exist in the united states, which limits opportunities for architects to gain first-hand experience and familiarity. familiarity with clt and other modern ewps has been reported as low amongst architects across the united states. a 2015 study found that only 4.3% of responding architects were “very familiar” with clt construction (mallo and espinoza 2015). surveys of architectural firms indicated that 42.3% had learned of clt through magazines and 20.3% through the internet (mallo and espinoza 2015). only 17.5% gained primary information through professional conferences and workshops. as such, knowledge, experience, and familiarity regarding engineered wood products remains nascent among architects in the united states. (mallo and espinoza 2015). the research that does exist, on both leed certification and ewps, has largely been concentrated in regions outside the us south, such as the pacific northwest region. aside from architects, general audiences also lack experience and familiarity with ewps and expresses concern regarding both the safety of these structures in the event of fire and their environmental impacts (larasatie et al. 2018; gosselin et al. 2017). for example, when asked questions about their perceptions of wood use, general audiences tend to view wood construction as a contributor to deforestation. from this perspective, like architects, clients may have a varied attitudes, knowledge, and experience and familiarity with leed and/or ewps. research objectives a dearth of literature exists that examines the views of architects within localized us regions that have substantial forest resources and timber markets, like those in the southeastern united states. arkansas, for example, maintains significant forest resources and timber industry interests but little is known of architects’ perspectives on leed and ewps. in anticipation of emergent opportunities for sustainable building design initiatives with ewps, there is a need to focus on architects within this region to better understand their perspective. accordingly, this study poses the following research questions: rq1a. what level of familiarity/experience do arkansas-based architects have with leed certification? rq1b. to what extent do arkansas-based architects perceive their clients to have familiarity/experience with leed? journal of sustainable architecture and civil engineering 2020/2/27 20 methods rq2. what are arkansas-based architects’ attitudes towards leed and leed sustainability goals in the context building design? rq3. what level of familiarity/experience do arkansas-based architects have with ewps? rq4a. what are arkansas-based architects’ attitudes towards the characteristics of ewps, in comparison to steel/concrete? rq4b. what level of concerns with ewps do arkansas-based architects express? study context structural wood use in the united states is highest in the western states and lowest in the south (kozak and cohen 1999). in arkansas, to date, over 200 leed certified buildings have been erected, but ewp use is minimal (usgbc 2019c). in 2019, the university of arkansas’ fayetteville campus began construction of student dormitories that use prefabricated clt panels imported from europe (black 2017). other projects incorporating non-clt wood products have been assembled within arkansas to demonstrate the aesthetic value and cost-effectiveness of wood-framed construction. one example is el dorado high school, which prominently features glue-laminated timber as both a structural and externally visible component. however, these few examples demonstrate the limited accessibility and high cost of projects incorporating clts. yet, the southern us produces more than 50% of the nation’s construction lumber (howard and jones 2013). over the last 40 years, forests in the u.s. south have been accumulating biomass at a rate of more than 2 billion cubic feet for year since 1963 (wear and greis 2012). this increase in forest biomass is an opportunity for economic development and alleviate environmental concern of forest overstocking, which can have deleterious effects on forest health. data collection to collect information from arkansas-based architects, a questionnaire was developed that focused on sustainable building design, leed certification and sustainability goals, and ewps, including clt. question design followed previous studies that employed likert-scales type items (sutton 1998; wastiels and wouters 2012). following an initial question formulation stage, a draft questionnaire was piloted and administered to four registered architects practicing in arkansas to assess clarity and wording; results and feedback were incorporated into the final questionnaire. the final version of the questionnaire was approved by the university of arkansas at monticello institution review board (fnr 1-185). the study population was architects holding a membership with the arkansas chapter of the american institute of architects (aia). to reach this target group, we contacted organizational leadership to facilitate member participation. the resulting sample frame consisted of all active, registered aia members (n = 589). the aia distributed a questionnaire link via their electronic mailing list, with each recipient provided access to the questionnaire hosted by qualtrics. data collection occurred between june and august 2018. following the initial invitation to participate, a reminder email was distributed to the sample approximately every two-weeks until no new responses were obtained. after data collection, data were cleaned in accordance with standard survey practices (ruel, wagner, and gillespie 2015; vaske 2008). measures to assess what level of familiarity and experience arkansas-based architects have with leed certification, one likert-scale type question asked, “are you interested in leed compliant building design?” (1 = yes, 2 = no, 3 = somewhat); and four questions asked, “what levels of leed certification did you apply for [your building designs receive] before [after] 2014?” (1 = certified, 2 = silver, 3 = gold, 4 = platinum, 5 = none). to assess the extent to which arkansas-based architects 21 journal of sustainable architecture and civil engineering 2020/2/27 perceive their clients to have familiarity/experience with leed, two questions asked, “are your clients interested in leed compliant building design” (1 = yes, 2 = no, 3 = somewhat); and “have you developed leed compliant building designs for a client” (1 = yes, 2 = no). to gauge opinions on the seven sustainability goals derived from leed v4 impact categories, participants were asked, “how important a consideration are these sustainability goals to you when designing a building?” (1 = not at all important, 5 = extremely important). the leed v4 impact categories summarize intended outcomes of any leed project. these goals include: “reverse contribution to global climate change”, “enhance individual human health and well-being”, “protect and restore water resources”, “protect, enhance, and restore biodiversity and ecosystem services”, “promote sustainable and regenerative material resources cycles”, “build a greener economy”, and “enhance social equity, environmental justice, and community quality of life” (owens, rohloff, and rosenberg 2013). for the purposes of this questionnaire, the wording of these seven sustainability goals derived from these impact categories were modified to improve clarity and specificity (table 2). table 2 comparison of leed v4’s impact categories and the sustainability goals in the questionnaire presented to arkansas architects leed v4 impact category sustainability goal 1 reverse contribution to global climate change mitigating global climate change 2 enhance individual human health and well-being improving human health and well-being 3 protect and restore water resources protecting, conserving, and restoring water resources 4 protect, enhance and restore biodiversity and ecosystem services protecting and restoring natural ecosystems and biodiversity 5 promote sustainable and regenerative material resource cycles increasing use of renewable/recyclable materials to reduce environmental impacts 6 build a greener economy building an economy that reduces environmental risks and ecological scarcities 7 enhance social equity, environmental justice, community health and quality of life creating a strong sense of place that is socially and environmentally inclusive next, to examine arkansas-based architects’ attitude towards leed and leed sustainability goals (derived from leed v4 impact categories) in the context building design, one semantic differential scale questions asked, “overall, how would you rate your experience(s) with the leed certification system” (1 = extremely negative, 5 = extremely positive). to assess levels of familiarity and experience with ewps, two questions asked, “prior to this survey, how familiar were you with these wood products?” (1 = not at all, 5 = a great deal) and “have you used these wood products in your building designs?” (1 = yes, 2 = no). attitude towards ewp was first assessed by asking participants, “how well do engineered wood products—like laminated beams and cross-laminated timber—perform in the face of natural forces in comparison to steel and concrete construction?” (1 = much worse, 5 = much better). next, participants were asked their opinion of ewp performance under select natural conditions (fire, earthquake, flooding, tornado, and seasonal climate cycles) compared to steel/concrete, i.e., “how important a consideration are these sustainability goals to you when you use engineered wood products (or considering using them) in your building design?” (1 = not at all important, 5 = extremely important). finally, to examine what level of concern arkansas-based architects express towards ewps factors (in terms of safety, durability, client acceptance, cost/price, assembly complication, aesthetic journal of sustainable architecture and civil engineering 2020/2/27 22 results value, environmental impacts, availability/sourcing, and prestige), participants were asked, “to what extent do these considerations limit your use of engineered wood products in your building designs” (1 = not at all, 5 = a great deal). the last section of the survey instrument asked standard sociodemographic questions. analysis standard descriptive statistics were generated for data exploration and initial summary of responses. non-response bias was tested by using late responses as a proxy for non-respondents to test for non-response bias (ruel, wagner, and gillespie 2015). t-tests were used to compare earlyand late-responses for significant differences using α=0.05. the next stage of analysis involved a series of single factor analysis of variance (anova). this allowed for comparisons to be drawn between categories for multi-faceted questions. with this, it was possible to determine whether significant differences existed between these categories. mean scores were compared with a tukey’s test. a series of paired two-sample t-tests were also used to compare the sample means for architect and client interest in leed and paired questions involving the seven leed sustainability goals with regards to design only and design with engineered wood products. in total, 88 responses were received for the questionnaire. however, four answer sets were discarded due to a lack of any response on questions. out of the remaining 84 responses, 67 were entirely complete and 17 were partially complete. using the american association for public opinion research (aapor) outcome rate calculator (aapor 2016), we calculated a response rate of 14.3%. the average time on this questionnaire was 7 minutes and 26 seconds. response rates of similar surveys of architects (bysheim and nyrud 2009; wear and greis 2012) were between 11.6 and 21.4 percent. in all 19 questions, no significant differences were found between early and late responders, inferring a lack of non-response bias. of the respondents, 76.8% were male and 23.2% female. a majority of 89.7% self-identified as white. black or african american respondents made up 2.9% of the sample group, and 7.6% identified their race as “other”. additionally, 55.7% of respondents stated they were not a member of the us green building council, while 44.3% indicated that they were. when asked to report the highest level of education attained, 75% of respondents indicated a bachelor’s degree as their answer. a smaller percentage of 23.5% have received a master’s degree, and 1.5% have graduate at the phd level. additionally, at 71%, a large majority of respondents indicated that their highest educational degree was received at the university of arkansas. results indicated that architects held some interest in leed certification, with 67.9% affirming an interest in the program. they were also asked to evaluate the interests of their clients. architects perceive that their clients possess less interest in leed, with 59.5% stating that their clients were only somewhat interested. a paired two-sample t-test revealed that architects reported significantly greater interest in leed certification for themselves than what they feel their clients hold (“architects”; x− = 1.7, s = 0.5… “clients”; x− = 1.0, s=0.6… “t-test”; t(9.9)… “p value”; p<0.05). within the sample group, 67.5% of architects affirmed they had previously developed leed-compliant designs, while 32.5% had not. amongst those respondents that had designed for leed, 7.5% had not received certification prior to 2014, the year in which leed v4 was introduced. conversely, 27.5% of respondents have not received leed certification for any project developed after 2014. of those that applied prior to 2014, a combined 38.3% received either the gold or platinum rating for a submitted design. for versions of leed preceding v4, only designs at these levels are considered substantially efficient in terms of energy use and renewability (scofield 2013). following 2014 and the introduction of v4, 23.6% of architects who had successfully applied for certification received the gold and platinum ratings. 23 journal of sustainable architecture and civil engineering 2020/2/27 age respondents 18-24 1 25-35 13 36-44 24 45-54 15 55-64 8 65+ 8 highest level of education respondents bachelor’s degree 51 master’s degree 16 phd 1 table 3 reported demographic data of aia arkansas registered architects. respondents reported on age and education level when rating the importance of sustainability goals in relation to engineered wood product use, “increasing use of renewable/recyclable materials to reduce environmental impacts” received the highest score, while “mitigating global climate change” once again received the lowest score (“increasing use of renewable/recyclable materials”; x̅ = 3.9, sd = 0.8… “mitigating global climate change”; x̅ = 3.3, sd = 1.2) . anova indicated a difference in the means, and tukey’s means difference test (α=0.05) determined that the score related to “renewable material use”, “sense of place”, and “improving human health and wellbeing” differed significantly from ratings assigned to “mitigating global climate change” (figure 2). figure 1—ranked mean importance of leed derived sustainability goals by aia architects in arkansas in 2018. error bars represent 1 standard error. categories with different letter subscripts are significantly different (α= 0.05). [a] [ab] [ab] [ab] [ab] [b] [b] 3 3,5 4 4,5 improving human health protecting water resources creating a strong sense of place increasing use of renewable/recyclable… protecting and restoring natural… building an economy that reduces… mitigating climate change importance rating su st ai na bi lit y g oa l when rating the importance of sustainability goals in relation to engineered wood product use, “increasing use of renewable/recyclable materials to reduce environmental impacts” received the highest score, while “mitigating global climate change” once again received the lowest score (“increasing use of renewable/recyclable materials”; x̅ = 3.9, sd = 0.8… “mitigating global climate change”; x̅ = 3.3, sd = 1.2) . anova indicated a difference in the means, and tukey’s means difference test (α=0.05) determined that the score related to “renewable material use”, “sense of place”, and “improving human health and wellbeing” differed significantly from ratings assigned to “mitigating global climate change” (figure 2). figure 1—ranked mean importance of leed derived sustainability goals by aia architects in arkansas in 2018. error bars represent 1 standard error. categories with different letter subscripts are significantly different (α= 0.05). [a] [ab] [ab] [ab] [ab] [b] [b] 3 3,5 4 4,5 improving human health protecting water resources creating a strong sense of place increasing use of renewable/recyclable… protecting and restoring natural… building an economy that reduces… mitigating climate change importance rating su st ai na bi lit y g oa l in regards to the reported importance of sustainability goals in relation to building design, improving human health and well-being received the highest mean score, while mitigating global climate change (“improving human health and well-being”; x− = 4.4, sd = 0.7… “mitigating global climate change”; x− = 3.7, sd = 1.2) received the lowest. based on 1-way anova results, a significant difference was present amongst the mean scores. results of the tukey’s means test indicate that the sustainability goal surrounding human health significantly differs from mitigating climate change and building an economy that reduces environmental risks and ecological scarcities (fig. 1). fig. 1 ranked mean importance of leed derived sustainability goals by aia architects in arkansas in 2018 error bars represent 1 standard error. categories with different letter subscripts are significantly different (α= 0.05) when rating the importance of sustainability goals in relation to engineered wood product use, “increasing use of renewable/recyclable materials to reduce environmental impacts” received the highest score, while “mitigating global climate change” once again received the lowest score (“increasing use of renewable/recyclable materials”; x− = 3.9, sd = 0.8… “mitigating global climate change”; x− = 3.3, sd = 1.2). anova indicated a difference in the means, and tukey’s means difference test (α=0.05) determined that the score related to “renewable material use”, “sense of place”, and “improving human health and wellbeing” differed significantly from ratings assigned to “mitigating global climate change” (fig. 2). journal of sustainable architecture and civil engineering 2020/2/27 24 fig. 2 ranked mean importance of sustainability goals as they relate to the use of engineered wood products by architects in arkansas, 2018 black bars are used to indicate the standard error of each category. categories with different letter subscripts are significantly different (α = 0.05) sustainability goal mean importance rating standard error p-value building design wood use building design wood use mitigating global climate change 3.71 3.26 0.181 0.169 0.0004 improving human health and well-being 4.41 3.82 0.055 0.126 <0.000 protecting, conserving, and restoring water resources 4.16 3.50 0.085 0.139 <0.000 protecting and restoring natural ecosystems and biodiversity 4.06 3.69 0.090 0.120 0.0028 increasing use of renewable/recyclable materials to reduce environmental impacts 4.07 3.88 0.070 0.078 0.0628 building an economy that reduces environmental risks and ecological scarcities 3.91 3.60 0.097 0.127 0.0156 creating a strong sense of place that is socially and environmentally inclusive 4.10 3.84 0.113 0.151 0.0132 table 4 comparison of mean importance ratings of sustainability goals in relation to building design and the use of engineered wood products by architects in arkansas next, the mean importance ratings issued to each sustainability goal were compared between general building design and building design using engineered wood products. for these t-tests, significant differences were found to exist between all but one paired set of answers: 1) mitigating global climate change (p<0.05), 2) improving human health and well-being (p<0.05), 3) protecting, conserving and restoring water resources (p<0.05), 4) protecting and restoring natural ecosystems and biodiversity (p = 0.00), 5) increasing use of renewable/recyclable materials to reduce environmental impacts (p = 0.06), 6) building an economy that reduces environmental risks and ecological scarcities (p = 0.01), 7) creating a strong sense of place that is socially and environmentally inclusive (p = 0.01). no difference could be detected for the “increasing use of renewable/recyclable materials to reduce environmental impacts” goal. for every other goal category, mean importance ratings provided by architects were significantly lower when considering the use of engineered wood products (table 4). next, the mean importance ratings issued to each sustainability goal were compared between general building design and building design using engineered wood products. for these t-tests, significant differences were found to exist between all but one paired set of answers: 1) mitigating global climate change (p<0.05), 2) improving human health and well-being (p<0.05), 3) protecting, conserving and restoring water resources (p<0.05), 4) protecting and restoring natural ecosystems and biodiversity (p = 0.00), 5) increasing use of renewable/recyclable materials to reduce environmental impacts (p = 0.06), 6) building an economy that reduces environmental risks and ecological scarcities (p = 0.01), 7) creating a strong sense of place that is socially and environmentally inclusive (p = 0.01). no difference could be detected for the “increasing use of renewable/recyclable materials to reduce environmental impacts” goal. for every other goal category, mean importance ratings provided by architects were significantly lower when considering the use of engineered wood products (table 4). architects’ familiarity with four specific engineered wood products: plywood panels, glue-laminated timber, cross-laminated timber (clt), and dowel-laminated timber (dlt) is shown in figure 3. from 77 responses, it was concluded that architects hold a significantly greater familiarity with plywood panels and gluelaminated timber over clt and dlt. of all the products, dlt received the lowest score of familiarity (“plywood panels”; x̅ = 4.2, sd = 0.9… “glue-laminated timber”; x̅ = 4.1, sd = 0.9… “clt”; x̅ = 3.3, sd = 1.0… “dlt”; x̅ =2.4, sd = 1.1… “p value”; p<0.05). architects have incorporated engineered wood products into their building designs. out of the 77 respondents, 83.1% affirmed their use of plywood panels, while 89.6% had incorporated glue-laminated timber into a previous design. mean usage rates for these two products did not differ significantly. clt and dlt were reported to have been used by 20.8% and 7.8% of respondents, respectively. the use of clt and dlt both differed from all other products and was found to be considerably lower than plywood panels or glue-laminated figure 2—ranked mean importance of sustainability goals as they relate to the use of engineered wood products by architects in arkansas, 2018... black bars are used to indicate the standard error of each category. categories with different letter subscripts are significantly different (α= 0.05). [a] [a] [ab] [ab] [ab] [ab] [b] 3 3,5 4 increasing use of renewable/recyclable materials creating a strong sense of place improving human health protecting and restoring natural ecosystems building an economy that reduces environmental risks and scarcities protecting water resources mitigating climate change importance rating su st ai na bi lit y g oa l next, the mean importance ratings issued to each sustainability goal were compared between general building design and building design using engineered wood products. for these t-tests, significant differences were found to exist between all but one paired set of answers: 1) mitigating global climate change (p<0.05), 2) improving human health and well-being (p<0.05), 3) protecting, conserving and restoring water resources (p<0.05), 4) protecting and restoring natural ecosystems and biodiversity (p = 0.00), 5) increasing use of renewable/recyclable materials to reduce environmental impacts (p = 0.06), 6) building an economy that reduces environmental risks and ecological scarcities (p = 0.01), 7) creating a strong sense of place that is socially and environmentally inclusive (p = 0.01). no difference could be detected for the “increasing use of renewable/recyclable materials to reduce environmental impacts” goal. for every other goal category, mean importance ratings provided by architects were significantly lower when considering the use of engineered wood products (table 4). architects’ familiarity with four specific engineered wood products: plywood panels, glue-laminated timber, cross-laminated timber (clt), and dowel-laminated timber (dlt) is shown in figure 3. from 77 responses, it was concluded that architects hold a significantly greater familiarity with plywood panels and gluelaminated timber over clt and dlt. of all the products, dlt received the lowest score of familiarity (“plywood panels”; x̅ = 4.2, sd = 0.9… “glue-laminated timber”; x̅ = 4.1, sd = 0.9… “clt”; x̅ = 3.3, sd = 1.0… “dlt”; x̅ =2.4, sd = 1.1… “p value”; p<0.05). architects have incorporated engineered wood products into their building designs. out of the 77 respondents, 83.1% affirmed their use of plywood panels, while 89.6% had incorporated glue-laminated timber into a previous design. mean usage rates for these two products did not differ significantly. clt and dlt were reported to have been used by 20.8% and 7.8% of respondents, respectively. the use of clt and dlt both differed from all other products and was found to be considerably lower than plywood panels or glue-laminated figure 2—ranked mean importance of sustainability goals as they relate to the use of engineered wood products by architects in arkansas, 2018... black bars are used to indicate the standard error of each category. categories with different letter subscripts are significantly different (α= 0.05). [a] [a] [ab] [ab] [ab] [ab] [b] 3 3,5 4 increasing use of renewable/recyclable materials creating a strong sense of place improving human health protecting and restoring natural ecosystems building an economy that reduces environmental risks and scarcities protecting water resources mitigating climate change importance rating su st ai na bi lit y g oa l 3,53 mean ratings for each sustainability goal are provided under both the building design and wood use categories. p-values are provided to indicate significant differences between means 25 journal of sustainable architecture and civil engineering 2020/2/27 figure 3—mean reported familiarity of engineered wood products amongst architects in arkansas, 2018. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). the limiting factors of greatest impact included cost/price, availability/sourcing, durability, and client acceptance. cost/price and availability/sourcing were found to differ significantly from environmental impacts, safety, and prestige (“cost/price”; x̅ = 4.2, sd = 1.0… “availability/sourcing”; x̅ = 3.9, sd = 1.1… “durability”; x̅ = 3.8, sd = 1.0… “client acceptance”; x̅ =3.8, sd = 1.2… “assembly complication”; x̅ = 3.6, sd = 1.1… “aesthetic value”; x̅ = 3.6, sd = 1.2… “environmental impacts”; x̅ = 3.2, sd = 1.1… “safety”; x̅ = 3.2, sd = 1.3… “prestige” = x̅ = 2.0, sd = 1.2… “p value”; p<0.05).the former categories were ranked as having the greatest ability to limit wood product use, while the latter factors were of lesser impact. out of all factors, prestige was reported as having the lowest degree of impact, and significantly differed from all other categories (figure 5). [a] [a] [b] [c] 0 1 2 3 4 plywood panels glue-laminated timber cross-laminated timber dowel-laminated timber familiarity rating figure 4—mean usage of engineered wood products in architectural designs amongst architects in arkansas, 2018. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). [a] [a] [b] [b] 0 0,2 0,4 0,6 0,8 1 glue-laminated timber plywood panels cross-laminated timber dowel-laminated timber use rating fig. 3 mean reported familiarity of engineered wood products amongst architects in arkansas, 2018 black bars indicate standard error. categories with different letter subscripts are significantly different (α = 0.05) figure 3—mean reported familiarity of engineered wood products amongst architects in arkansas, 2018. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). the limiting factors of greatest impact included cost/price, availability/sourcing, durability, and client acceptance. cost/price and availability/sourcing were found to differ significantly from environmental impacts, safety, and prestige (“cost/price”; x̅ = 4.2, sd = 1.0… “availability/sourcing”; x̅ = 3.9, sd = 1.1… “durability”; x̅ = 3.8, sd = 1.0… “client acceptance”; x̅ =3.8, sd = 1.2… “assembly complication”; x̅ = 3.6, sd = 1.1… “aesthetic value”; x̅ = 3.6, sd = 1.2… “environmental impacts”; x̅ = 3.2, sd = 1.1… “safety”; x̅ = 3.2, sd = 1.3… “prestige” = x̅ = 2.0, sd = 1.2… “p value”; p<0.05).the former categories were ranked as having the greatest ability to limit wood product use, while the latter factors were of lesser impact. out of all factors, prestige was reported as having the lowest degree of impact, and significantly differed from all other categories (figure 5). [a] [a] [b] [c] 0 1 2 3 4 plywood panels glue-laminated timber cross-laminated timber dowel-laminated timber familiarity rating figure 4—mean usage of engineered wood products in architectural designs amongst architects in arkansas, 2018. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). [a] [a] [b] [b] 0 0,2 0,4 0,6 0,8 1 glue-laminated timber plywood panels cross-laminated timber dowel-laminated timber use rating architects’ familiarity with four specific engineered wood products: plywood panels, glue-laminated timber, cross-laminated timber (clt), and dowel-laminated timber (dlt) is shown in fig. 3. from 77 responses, it was concluded that architects hold a significantly greater familiarity with plywood panels and glue-laminated timber over clt and dlt. of all the products, dlt received the lowest score of familiarity (“plywood panels”; x− = 4.2, sd = 0.9… “glue-laminated timber”; x− = 4.1, sd = 0.9… “clt”; x− = 3.3, sd = 1.0… “dlt”; x− =2.4, sd = 1.1… “p value”; p<0.05). architects have incorporated engineered wood products into their building designs. out of the 77 respondents, 83.1% affirmed their use of plywood panels, while 89.6% had incorporated glue-laminated timber into a previous design. mean usage rates for these two products did not differ significantly. clt and dlt were reported to have been used by 20.8% and 7.8% of respondents, respectively. the use of clt and dlt both differed from all other products and was found to be considerably lower than plywood panels or glue-laminated timber. dlt received the lowest use rating (“plywood panels”; x− = 0.8, sd = 0.4… “glue-laminated timber”; x− = 0.9, sd = 0.3… “clt”; x− = 0.21, sd = 0.4… “dlt”; x− = 0.08, sd = 0.3) (fig. 4). fig. 4 mean usage of engineered wood products in architectural designs amongst architects in arkansas, 2018 black bars indicate standard error. categories with different letter subscripts are significantly different (α = 0.05) figure 3—mean reported familiarity of engineered wood products amongst architects in arkansas, 2018. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). the limiting factors of greatest impact included cost/price, availability/sourcing, durability, and client acceptance. cost/price and availability/sourcing were found to differ significantly from environmental impacts, safety, and prestige (“cost/price”; x̅ = 4.2, sd = 1.0… “availability/sourcing”; x̅ = 3.9, sd = 1.1… “durability”; x̅ = 3.8, sd = 1.0… “client acceptance”; x̅ =3.8, sd = 1.2… “assembly complication”; x̅ = 3.6, sd = 1.1… “aesthetic value”; x̅ = 3.6, sd = 1.2… “environmental impacts”; x̅ = 3.2, sd = 1.1… “safety”; x̅ = 3.2, sd = 1.3… “prestige” = x̅ = 2.0, sd = 1.2… “p value”; p<0.05).the former categories were ranked as having the greatest ability to limit wood product use, while the latter factors were of lesser impact. out of all factors, prestige was reported as having the lowest degree of impact, and significantly differed from all other categories (figure 5). [a] [a] [b] [c] 0 1 2 3 4 plywood panels glue-laminated timber cross-laminated timber dowel-laminated timber familiarity rating figure 4—mean usage of engineered wood products in architectural designs amongst architects in arkansas, 2018. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). [a] [a] [b] [b] 0 0,2 0,4 0,6 0,8 1 glue-laminated timber plywood panels cross-laminated timber dowel-laminated timber use rating figure 3—mean reported familiarity of engineered wood products amongst architects in arkansas, 2018. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). the limiting factors of greatest impact included cost/price, availability/sourcing, durability, and client acceptance. cost/price and availability/sourcing were found to differ significantly from environmental impacts, safety, and prestige (“cost/price”; x̅ = 4.2, sd = 1.0… “availability/sourcing”; x̅ = 3.9, sd = 1.1… “durability”; x̅ = 3.8, sd = 1.0… “client acceptance”; x̅ =3.8, sd = 1.2… “assembly complication”; x̅ = 3.6, sd = 1.1… “aesthetic value”; x̅ = 3.6, sd = 1.2… “environmental impacts”; x̅ = 3.2, sd = 1.1… “safety”; x̅ = 3.2, sd = 1.3… “prestige” = x̅ = 2.0, sd = 1.2… “p value”; p<0.05).the former categories were ranked as having the greatest ability to limit wood product use, while the latter factors were of lesser impact. out of all factors, prestige was reported as having the lowest degree of impact, and significantly differed from all other categories (figure 5). [a] [a] [b] [c] 0 1 2 3 4 plywood panels glue-laminated timber cross-laminated timber dowel-laminated timber familiarity rating figure 4—mean usage of engineered wood products in architectural designs amongst architects in arkansas, 2018. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). [a] [a] [b] [b] 0 0,2 0,4 0,6 0,8 1 glue-laminated timber plywood panels cross-laminated timber dowel-laminated timber use rating the limiting factors of greatest impact included cost/price, availability/sourcing, durability, and client acceptance. cost/price and availability/sourcing were found to differ significantly from environmental impacts, safety, and prestige (“cost/price”; x− = 4.2, sd = 1.0… “availability/sourcing”; x− = 3.9, sd = 1.1… “durability”; x− = 3.8, sd = 1.0… “client acceptance”; x− =3.8, sd = 1.2… “assembly complication”; x− = 3.6, sd = 1.1… “aesthetic value”; x− = 3.6, sd = 1.2… “environmental impacts”; journal of sustainable architecture and civil engineering 2020/2/27 26 seventy respondents supplied an answer to this question of ewp performance compared to steel and concrete. the mean scores were determined for fire, earthquake, flooding, tornado, and seasonal climate cycles (“fire”; x̅ = 0.2, sd = 1.0… “earthquake”; x̅ = 0.5, sd = 0.8… “flooding”; x̅ = -0.5, sd = 0.9… “tornado” = x̅ = -0.2, sd = 0.9… “seasonal climate cycles”; x̅ = 0.1, sd = 1.0… “p value”; p<0.05). responses differed significantly from 0 for the performance of engineered wood products when exposed to earthquakes, fire, tornados, and flooding. no difference was detected for seasonal climate cycles. engineered wood product performance under earthquake conditions was rated the highest, while flood performance received the lowest score. based on anova, the performance ratings for earthquake was significantly different from seasonal climate cycles, tornado, and flooding (figure 6). comparing responses regarding concerns and limitations associated with engineered wood actually and the stated use of those products allows and exploration of the real impact of those concerns. flooding was the natural force most likely inhibit the wood use due to its low performance rating amongst architects (figure 6), and similarly concluded that cost/price was the limiting factor most likely to influence use (figure 5). figure 5—ranked mean scores for factors which limit use of engineered wood products in architectural designs. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). [a] [a] [ab] [ab] [abc] [abc] [bc] [c] [d] 1 1,5 2 2,5 3 3,5 4 4,5 cost/price availability/sourcing durability client acceptance assembly complication aesthetic value environmental impacts safety prestige limitation score li m iti ng f ac to r fig. 5 ranked mean scores for factors which limit use of engineered wood products in architectural designs black bars indicate standard error. categories with different letter subscripts are significantly different (α = 0.05) fig. 6 mean performance ratings of engineered wood products relative to steel and concrete construction by architects in arkansas 5. discussion 5.1. familiarity and experience with leed certification? respondents were largely both interested in and engaged with the leed certification program, with roughly two thirds of respondents indicating prior participation. this suggests that concepts such as sustainable design and green building certification have already gained a degree of traction within the state of arkansas. however, aia architects also believe that their clientele were significantly less interest in leed certification than the architects themselves. this may represent a barrier to a more consistent and widespread application of the leed program, as paying clients ultimately retain control over major design decisions. architects, however, can serve as an essential component to promoting the benefits of green design and thus generate interest from their clients. addressing the concerns and priorities held by architects interested in environmental design, especially in relation to engineered wood products can promote the recognition of ewps as environmentally sustainable design elements. 5.2. attitude towards leed and sustainability goals out of the seven sustainability goals derived from the leed v4’s impact categories, improving human health and wellbeing was rated as being the most important. to promote leed within the region, it will likely be necessary to emphasize the positive effects that green design has on factors such as the physical and mental health of occupants. to that end, previous research has uncovered a link between certified green buildings and improved respiratory health, as well as a reduction in self-reported stress and depression amongst occupants of leed certified buildings (o’connor et al. 2004). in addition to improving human wellbeing, the sustainability goal of protecting water resources was also amongst those rated highly by respondents. with leed v4’s heightened focus on renewable material cycles and wood use, ecosystem benefits deriving from sustainable forest management, such as water quality figure 6—mean performance ratings of engineered wood products relative to steel and concrete construction by architects in arkansas. black bars indicate standard error. categories with different letter subscripts are significantly different (α= 0.05). [a] [ab] [b] [b] [b] -1 -0,5 0 0,5 1 earthquake fire seasonal climate cycles tornado flooding performance rating n at ur al f or ce black bars indicate standard error. categories with different letter subscripts are significantly different (α = 0.05) x− = 3.2, sd = 1.1… “safety”; x− = 3.2, sd = 1.3… “prestige” = x− = 2.0, sd = 1.2… “p value”; p<0.05).the former categories were ranked as having the greatest ability to limit wood product use, while the latter factors were of lesser impact. out of all factors, prestige was reported as having the lowest degree of impact, and significantly differed from all other categories (fig. 5). seventy respondents supplied an answer to this question of ewp performance compared to steel and concrete. the mean scores were determined for fire, earthquake, flooding, tornado, and seasonal climate cycles (“fire”; x− = 0.2, sd = 1.0… “earthquake”; x− = 0.5, sd = 0.8… “flooding”; x− = -0.5, sd = 0.9… “tornado” = x− = -0.2, sd = 0.9… “seasonal climate cycles”; x− = 0.1, sd = 1.0… “p value”; p<0.05). responses differed significantly from 0 for the performance of engineered wood products when exposed to earthquakes, fire, tornados, and flooding. no difference was detected for seasonal climate cycles. engineered wood product performance under earthquake conditions was rated the highest, while flood performance received the lowest score. based on anova, the performance ratings for earthquake was significantly different from seasonal climate cycles, tornado, and flooding (fig. 6). comparing responses regarding concerns and limitations associated with engineered wood actually and the stated use of those products allows and exploration of the real impact of those concerns. flooding was the natural force most likely inhibit the wood use due to its low performance rating amongst architects (fig. 6), and similarly concluded that cost/price was the limiting factor most likely to influence use (fig. 5). 27 journal of sustainable architecture and civil engineering 2020/2/27 discussion familiarity and experience with leed certification? respondents were largely both interested in and engaged with the leed certification program, with roughly two thirds of respondents indicating prior participation. this suggests that concepts such as sustainable design and green building certification have already gained a degree of traction within the state of arkansas. however, aia architects also believe that their clientele were significantly less interest in leed certification than the architects themselves. this may represent a barrier to a more consistent and widespread application of the leed program, as paying clients ultimately retain control over major design decisions. architects, however, can serve as an essential component to promoting the benefits of green design and thus generate interest from their clients. addressing the concerns and priorities held by architects interested in environmental design, especially in relation to engineered wood products can promote the recognition of ewps as environmentally sustainable design elements. attitude towards leed and sustainability goals out of the seven sustainability goals derived from the leed v4’s impact categories, improving human health and wellbeing was rated as being the most important. to promote leed within the region, it will likely be necessary to emphasize the positive effects that green design has on factors such as the physical and mental health of occupants. to that end, previous research has uncovered a link between certified green buildings and improved respiratory health, as well as a reduction in self-reported stress and depression amongst occupants of leed certified buildings (o’connor et al. 2004). in addition to improving human wellbeing, the sustainability goal of protecting water resources was also amongst those rated highly by respondents. with leed v4’s heightened focus on renewable material cycles and wood use, ecosystem benefits deriving from sustainable forest management, such as water quality improvement, could be presented to architects as a highlight of green building certification and sustainably produced clt. respondents appear mindful of the environmental impacts associated with their designs, and thus it will be important to demonstrate the sustainable practices which contribute to clt and other engineered wood products. it is understood that timber sequesters atmospheric carbon, while regular harvests allow newly regenerated forest stands to continue removing it through the processes of growth and respiration (fell 2011) in one case, a cradle to gate life cycle analysis on glue-laminated timbers produced in the us southeast showed that every cubic meter of glue-laminated material had a sequestered a net 1,083 kg of co2 (bergman and bowe 2011). despite this, architects within arkansas appear to believe that engineered wood products are less capable of promoting the sustainability goals of “protecting and restoring natural ecosystems and biodiversity” and “protecting, conserving, and restoring water resources”. this may indicate that architects remained concerned about wood construction’s contribution to deforestation and environmental degradation. architects may not be equally receptive to all facets of environmental protection and ecosystem restoration. one sustainability goal which did not rate especially high with arkansas architects is “mitigating global climate change”. this issue may not resonate as strongly with architects or their clientele within the target region, and thus demonstrations of leed and clt’s carbon reduction potential may not serve to generate interest. alternatively, it is possible that architects and their clients may not be aware how one building or one design can mitigate climate change, or how long-term sequestration of carbon in wood products as well as forests is a viable strategy for carbon sequestration, especially when carbon trading programs often do not grant carbon credits for increased use of wood. familiarity and experience with ewps architects tended to be most familiar with well-established and prolific examples of engineered wood products, which is intuitively sound. plywood panels and glue-laminated timber are esjournal of sustainable architecture and civil engineering 2020/2/27 28 conclusions pecially popular design elements incorporated into a broad spectrum of architectural plans. no significant difference in familiarity was detected between these two products, with both having received the highest mean familiarity scores amongst the ewps presented. on the other hand, clt was a relatively lesser known material as compared to the aforementioned examples, which should not register as particularly unexpected given its slow adoption within the us. unsurprisingly, actual use of newly developed ewps such as clt and dlt are significantly lower than that of plywood panels and glue-laminated timber. attitude and concern towards ewps out of all potential limiting factor to ewps within the state, cost, availability, duration and client acceptance rated the highest in terms of degree of impact. previous research on the subject indicated that information barriers were amongst the chief limiters to ewp adoption but architects within this study region largely rate their knowledge of material as moderate to high, and thus cite other practical challenges as primary barriers (ahn et al. 2013). with costs being one of the greatest concerns, it should be noted that the cost competitiveness of a clt will often be dependent on the specifications of the building itself and the region in which it is erected. in scenarios in which clt is utilized, costs could be reduced when exposed wood is featured as an interior component (woodworks 2012). furthermore, reductions in construction time commonly associated with clt structures would further contribute to cost savings (woodworks 2012). in terms of availability and client acceptance, however, historically low demand within the region may impede adoption as opportunities to demonstrate the functional and aesthetic properties of new ewps are lacking. future projects cannot be expected to propagate without both the interest of property owners and the means to deliver limitations and future research of important note for this study is the possibility of bias in the respondent sample pool. as participation was entirely voluntary, it is possible that only architects especially interested in leed or environmental sustainability elected to respond. additionally, these results are only applicable to aia members within arkansas and may not be representative of all architects in the state. despite these limitations, this study illustrates the impressions that even environmentally conscientious architects hold about engineered wood and leed design, and thus study may serve as a valuable starting point for generating further interest amongst architects for these topics. regarding the data collection of this study, there is potential for ambiguity due to the nonspecific language used in some questions. asking architects to rate the importance of certain environmental goals may not be direct enough a question to ascertain what is truly meant by respondents. the issues related to wood use are complex, and other research as utilized a combination of qualitative and quantitative methods (o’connor et al. 2004; bysheim and nyrud 2009) to identify, if not avoid, ambiguity in data. we found that architects in arkansas are generally knowledgeable and interested in leed certification, but that their clientele are significantly less concerned with leed standards. while all sustainability goals are moderately to strongly important to architects in the state, there are significant differences in this importance. improving human health and well-being is significantly more important that building a green economy or mitigating climate change. hemström and others (2017) obtained similar results from architects in sweden. arkansas and swedish architects share similar importance on renewable/recyclable materials and construction costs arkansas architects expressed a belief that using ewps are less capable than other materials in protecting water quality and restoring natural ecosystems. yilmaz and bakis (2015) found that intensive use of natural resources created the perception of negative environmental impacts from wood 29 journal of sustainable architecture and civil engineering 2020/2/27 references use. in the u.s. south, plantation forestry has converted nearly 16.5 million hectares of natural forest since 1950 (wastiels and wouters 2012). certainly, this could lead to the perception that wood use is not particularly friendly to the environment and reduce the effort architects put into investigating wood use (hemström, mahapatra, and gustavsson 2017; mahapatra and gustavsson 2008). the use of emergent engineered wood products remains relatively low within the state of arkansas although interest and participation in the green building certification program, leed, appears to be quite high. although the perception is that clt performs comparably to steel and concrete construction, limited local manufacturing opportunities and increased cost incurrence, and inexperience with clt design and construction are likely the most prominent factors limiting further product use. a potential solution may be to facilitate collaborative development, design, and construction (gosselin et al. 2017). that is, sustainable design may have a higher probability of success when the forest and wood-products industry, developer and construction firms, and architects are incentivized to develop local collaborations in regions with the necessary private and public natural resources management infrastructure, like the southeastern us and eastern arkansas. acknowledgements funding for this research was provided by the usda wood innovations 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(412) 980-1818 e-mail: gabrielle.sherman@ maine.edu about the authors tamara walkingstick associate professor associate director for extension arkansas forest resource center main research area forest resources. address 2301 s. university ave. little rock, ar 722044940 tel. (501) 671-2000 e-mail: twalkingstick@uaex. edu kenneth wallen assistant professor university of arkansas at monticello college of forestry, agriculture & natural resources main research area forest resources. address p.o. box 3468 110 university ct. monticello, ar 71655 tel. (870) 460-1494 e-mail: wallen@uamont.edu matthew pelkki professor george h. clippert endowed chair university of arkansas at monticello college of forestry, agriculture & natural resources. main research area forest resources address p.o. box 3468 110 university ct. monticello, ar 71655 https://www.worldgbc.org/sites/default/files/ unep%20188_gabc_en%20%28web%29.pdf. us green building council, leed v4 (2019a), https://new.usgbc.org/leed-v4. us green building council, leed v4 building design + construction guide, (2019b), https://www.usgbc. org/guide/bdc#rp_overview. us green building council, usgbc arkansas (2019c), https://www.usgbc.org/usgbc-arkansas. van de lindt, j.w., pei, s., pryor, s.t., shimizu, h., isoda, h., experimental seismic response of a full-scale six-story light-frame wood building, journal of structural engineering 136 (10) (2010) 1262-1272, https:// doi.org/10.1061/(asce)st.1943-541x.0000222 vaske, j. j. survey research and analysis: applications in parks, recreation and human dimensions. venture publishing. state college, pa, us. 2008. wastiels, l., wouters, i., architects’ considerations while selecting materials. materials and design, 34 (2012), 584-593.https://doi.org/10.1016/j.matdes.2011.05.011 wear, d.n., greis, j.g., the southern forest futures project: summary report, usda forest service southern research station general technical report srs-168, (2012) 68. woodworks, cross laminated timber makes its mark with the long hall, woodworks (2012), https://www. woodworks.org/wp-content/uploads/clt-milestone-montana.pdf. yilmaz, m, bakis, a., sustainability in the construction sector, social and behavioral sciences, 19 (2015) 2253-2262.https://doi.org/10.1016/j.sbspro.2015.06.312 this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 34 darnioji architektūra ir statyba 2014. no. 1(6) journal of sustainable architecture and civil engineering issn 2029–9990 research of alkali silica reaction in concrete with active mineral additives audrius grinys*, vytautas bocullo, algirdas gumuliauskas kaunas university of technology, faculty of civil engineering and architecture, studentu g. 48, lt-51367 kaunas, lithuania. *corresponding author: audrius.grinys@ktu.lt, http://dx.doi.org/10.5755/j01.sace.6.1.6354 this paper analyses the effect of mineral additives on alkali silica reaction. amorphous sio2 contained in concrete aggregate is known for reactions with na2o and k2o that cause concrete expansion and cracking. concrete expansion is the result of silicates reaction (asr). alkali silica gel is a reaction product having expanding properties. expanding silica gel creates stress that causes concrete cracking. the paper investigates the elimination of the negative effect of asr by using fly ash as active mineral additive. in the tests active mineral additive (fly ash) is expected to reduce the effect of alkali silica reaction and volumetric strain. keywords: alkali silica reaction, mineral additives, fly ash, hydrated silicates, concrete, bonding agent. 1. introduction asr i.e. reaction of alkali and silica gel in granular matrix composites, is destruction caused by adverse chemical reactions between the alkali present in hardened concrete (na2o and k2o) and reactive silica or carbonate components present in the aggregates (gumuliauskas, navickas, 2007). such corrosion may even lead to structure failures; therefore it is very important to find ways to reduce it and produce alkali silica reaction resistant concrete. this issue has been investigated for more than 70 years; numerous tests have been conducted and described in scientific papers. during cement hardening sio2 reacts with na2o and k2o and hydrosilicate crystals of alkali metals with variable content of crystalized water are formed on the surface of reactive aggregates. such corrosion of concrete becomes especially visible on the surface of concrete structures, where pieces of opal aggregates are pressed out from the surface layer (balandis et al., 2006). in this case concrete destruction is caused by alkalisilica reaction (asr) in concrete mixture. usually alkali – silica reaction is an acid-base reaction between calcium hydroxide (ca(oh)2), otherwise known as portlandite, and silicic acid (h4sio4) or si(oh4), otherwise known as pozzolanic reaction, schematically represented as follows: ca(oh)2 + h4sio4 → ca2+ + h2sio42-+2h2o → cah2sio4 ∙ 2h2o (balandis et al., 2006) three conditions must be met for asr to occur: the reactive aggregate, high concentration of alkali in concrete pore solutions and humid environment of concrete (berube et al., 2002). asr occurs in concrete between silica present in the aggregate and alkali and hydroxide ions present in pore solutions forming liquid alkali silica gel. this gel absorbs water and may increase in volume and exert an expansive pressure inside the material. usually concrete expansions are in direct proportion to alkali concentration (berube et al., 2003). the composition of asr gel in exterior concrete structures may be different. the most common molar ratios of gel composite materials are 0.05 – 0.6 (na2o+k2o)/sio2 and 0 – 0.2 (cao+mgo)/sio2. the ratios may be different in places that are further from the reaction site, especially in reactions with calcium. t. knudsen and n. thaulow (1975) determined that in the majority of tested gels the molar ratio of na2o/sio2 ranged between 0.2 and 0.5 and cao content in asr gels ranged between 0 % and 20 %. michael thomas (2001) found that aggregate contained gel in 7-years-old concrete has a steady ca/si ratio of approx. 0.25 and k/ si ratio between 0.1–0.3. the bigger is the ca/si ratio, the smaller is the k/si ratio. the experimental test conducted by hou et al. (2004) showed that the gel of alkali hydrosilicate (a-s-h), similar to the gel reaction product (asr), is not formed when the paste of portlandite or portland cement containing calcium hydrosilicate with high calcium content and low silica content can react with silica. under the said conditions, additional calcium hydrosilicate is formed in the reaction of ca(oh)2 with melting silica, or gradual polymerization of calcium hydrosilicate. a-s-h, where polymerization prevails, is formed after the depletion of portlandite and complete polymerization of calcium hydrosilicate. 35 basing on the aforementioned test results we may state that the formation of alkali hydrosilicates in the cement paste and concrete, involving the ordinary course of cement hydration reaction, increases the solution’s ph. oh ions react with reactive aggregate and consume the silica released in the reaction with ch and thus forming c-s-h until the entire ch present in the reaction zone is combined. according to r. dron and f. brivot (1993), the gel of hydrosilicate formed during the reaction is scattered far away from aggregate micropores and the channels connecting them. the gel reacts with ca2+ ions and expands causing the concrete to crack. however, it is not clear why the gel builds expansive pressure in the pores. z. p. bažant and a. steffens (2000) raised a hypothesis that concrete cracking is caused by the expansive pressure concentrated at the boundaries of the aggregate and cement paste, where the expansive pressure displaces the gel into surrounding pores. when these pores are filled, the pressure is released through the cracks. analysing the structure of concrete many researchers, including g. m. idorn (2001) and g. goltermann (1995), have concluded that aggregate expansion by the pressure created inside the aggregate is not homogeneous. such non-homogeneous expansion creates stress that is released by causing concrete to crack. based on the analysis of crack patterns japanese researchers tsuneki ichikawa and masazumi miura (2007) a modified mechanism of asr, in which a reaction rim generated around the asr-affected aggregate plays a significant role in the deterioration of concrete. their tests showed that alkali silicate cannot build the expansive pressure unless the aggregate is tightly pressed by the reaction rim. the reaction rim is slowly generated from the alkali silicate that covers the asr affected aggregate. the consumption of alkali hydroxide by the asr induces the dissolution of ca2+ ions into the pore solution. the alkali silicate then reacts with ca+ ions to convert to an insoluble tight and rigid reaction rim. the reaction rim allows the penetration of alkaline solution but prevents the leakage of viscous alkali silicate, so that the alkali silicate generated afterward by the asr is accumulated in the aggregate to give an expansive pressure enough for cracking the concrete. very tiny aggregate such as fly ash may not cause the deterioration of concrete, since the asr is completed before the formation of reaction rims. 2. experiment and active substance the aim of this paper is to determine the reactivity of aggregates obtained from the quarries in the nemunas and the neris river basins in lithuanian territory on alkali – silica reaction and to propose active mineral admixtures to prevent the deterioration of concrete. another objective is to propose and to test the methodology for the calculation of active mineral admixture content in order to neutralize portlandite in the process of alkali – silica reaction of the aggregates. for the experiment described in this paper fly ash from poland was used as an active mineral additive that supresses alkali – silica reaction. fly ash is one of the coal combustion products consisting of fine particles that are usually removed through the chimney with flue gas. according to the content of calcium oxide fly ash is divided into two groups: a group containing above 5 % cao (f class) and a group containing 15–35 % cao (c class). fly ash with low cao content mainly consists of silica dioxide and aluminium oxide in the form of aluminate glass with a certain amount of aluminium silicates and mullite crystals. free cao in class f fly ash reacts with alite (c3a) and forms calcium hydraluminates. such fly ash has binding properties (skripkiūnas, 2007). shafaatian et al. studies the mechanism of fly ash action in reducing asr effect. the experiments showed that fly ash reduces the amount of ohions in the solution, increases the strength of concrete specimens (yositake et al., 2013), (shafaatian et al., 2012) and reduces the dissolution of aggregates containing silica dioxide (shafaatian et al., 2012). usually, the expansion caused by asr can be controlled by replacing 25 % of the cement with fly ash. thomas et al. (2010) found that in cases where 25 % and 40 % of portland cement were replaced by fly ash concrete selling and cracking significantly reduced in all mixtures with different reactive aggregates. although mixtures with 40 % of fly ash were tested (thomas et al., 2010), only up to 30 % of portland cement by weight can be replaced by fly ash of class f because higher content of fly ash in the cement paste may have a negative effect on concrete strength (gengying li, 2006). such a situation limits the use of fly ash. gengying li (2006) proposes to mix nano-sio2 into fly ash. a small amount of nano-sio2 added to fly ash increases its pozzolanic activity and speeds up the pozzolanic reaction and thus improves concrete strength. the tests showed that nano-sio2 increases not only early but also later-age strength of concrete. in general, concrete with fly ash has a longer setting time and this is the reason for lower early-age strength compared to the strength after the same curing time in concrete with portland cement (olba, 2008). yoshitake et al. (2013), however, reported higher later-age strength of such concretes. it should be noted that the young modulus in concrete with fly ash is 1.2 times higher than in concrete without this admixture. esteves et al. (2012) also investigated the using of bio -mass fly ash as a pozzolanic admixture. although this type of ash is categorized as class c, it was found to have a positive effect of reducing the expansion caused by asr. 3. bonding agent cement as the main bonding agent was replaced by fly ash in the experiment. the selection of cement type is as much important as the type of aggregate because silica oxide and silica acid present in the aggregate react with alkali and oxides present in the cement. since water-soluble sodium and potassium oxides (na2o and k2o) present in the cement combine with oh ions and participate in asr reaction (astm c 1293), therefore the total alkali content calculated as na2oekv may not exceed 0.8 %. since the effect of mineral admixture was investigated, it was important to have the portland free of any impurities. to this end portland cement of class cem i 42.5 n produced 36 by ab “akmenės cementas”, i.e. pure portland cement with the compressive strength of 42.5 mpa with normal hardening rate was used in the experiment. composition off the cement: 63,13 % cao; 20,48 % sio2; 5,55 % al2o3; 3,58 % fe2o3; 0,73 % so3; 3,99 % mgo. mineral composition of the clinker is presented in table 1. table 1. composition of clinker c3s, % c2s, % c3a, % c4af, % 56,60 15,76 8,59 10,85 fly ash from poland was used as an active admixture of the composition presented in table 2. table 2. composition of fly ash substance test result (wt %) loss on ignition 5,74 so3 2,15 chlorides (cl-) <0,01 free cao 0,01 total cao 2,44 active sio2 37,33 sio2 48,79 al2o3 25,24 fe2o3 5,30 sio2 + al2o3 + fe2o3 79,33 mgo 2,37 soluble phosphates like p2o5 0,00222 (22 ± 1 mg/kg) na2o 0,86 k2o 3,56 na2oekv. 3,20 4. aggregates alkali present in the cement and water react with sio2 present in the aggregate. rocks, such as opal, chalcedony, chert, flint and similar types of rock with a large amount of amorphous sio2, mixed with sand and gravel grains most often cause the adverse reaction. therefore quarries uncontaminated with the said rocks are of great value (hou et al., 2004). for the variety of results, quarries of different contamination by such reactive particles were selected. the following quarries of the neris and the nemunas river basins in kaunas region were selected: ▪ kvesai quarry (the nemunas river basin); ▪ rizgonys quarry (the neris river basin); ▪ zatyšiai quarry (the neris river basin). historically, the quarries of the nemunas river basin are polluted with flint rock, therefore the kvesai quarry is taken as polluted with reactive rock, whereas rizgonys and zatyšiai quarries of the neris basin are much cleaner, although in practice all lithuanian quarries are more or less polluted with reactive rocks. thus, the biggest expansion is the most likely in specimens made with the aggregate from kvesai quarry, although the layers in every quarry are different and the final result might not be as predicted. two aggregate sizes were used for the experiment: coarse aggregate of 4/8 fraction and fine aggregate of 0/4 fraction. concrete mix, where alkali – silica reaction was most likely to occur, was used in the experiment as the control mix. a particularly reactive aggregate – chert of 4/8 fraction – was selected as the course aggregate in this mix. a qualitative x-ray analysis of the aggregates was done. x-ray diffraction curves of the specimens were obtained by diffractometer dron 6 (bourevestnik inc., russia) using monochromatized cu kα radiation (ni filter, step width of 0,020, counting time per step 0,5 s, plate voltage ua = 30 kv, current i = 20 ma). the test results showed (fig. 1–3) that all aggregates contained limestone (caco3) several varieties of sio2 and other minerals that do not participate in alkali – silicate reaction. the x-ray image of carbonate chert (fig. 3) distinguished of all other images: the mountain-shape concentration of peaks shows that the aggregate contains amorphous sio2, which reacts with the alkali and causes degradation. aggregates from the quarries were cleaner; the x-ray of the aggregate from kvesai quarry shows only small “peak mountains” between peaks that indicate the possible presence of amorphous sio2 fig. 1. a – caco3; b – sio2 (quartz); c – camg(co3)2; d – na al si3 o8 fig. 2. a sio2 (silica); b – caco3; c – camg(co3)2; d – (na, ka)(si3al)o8 37 fig. 3. a – caco3; b – sio2 (silica); c – sio2 (cristobalite) methodology for the neutralization of alkali-driven concrete degradation perennial and comprehensive studies of alkali – silica reaction enable to presume that 3 components are present in the process: amorphous sio2 (chert and flint), sodium and potassium hydroxide and calcium hydroxide. these components react in two stages (gumuliauskas, navickas 1992): ▪ at first sodium and potassium hydroxides react with amorphous sio2 forming alkaline hydrosilicate (water glass) that does not have any adverse effect on concrete, if only staining; ▪ in the second step the alkaline hydrosilicate reacts with calcium hydroxide ca(oh)2 (portlandite) that is produced after alite 3cao ∙ sio2, and later belite cao ∙ sio2, bind with water forming insoluble colloidal substance that builds a semipermeable membrane around the reactive particle of the aggregate. this membrane enables only unidirectional movement of materials accompanied by high osmotic pressure. the only way to prevent the adverse effect of the interaction of reactive aggregates with the alkali of cement clinker is to prevent the reaction of alkali and aggregate reaction products with cement clinker mineral hydrolysis product ca(oh)2, i.e. the cement must contain very fine pozzolanic admixtures, such as tripoli or crushed chert (at least 20 % of clinker weight) that would immediately react forming calcium silicates (gumuliauskas, navickas 1993); such reactive sio2 may be find in ground blast furnace slag, fly ash or sio2 micro-particles. in the binding process of concrete, at first portlandite ca(oh)2 is formed from alite (3cao ∙ sio2), the content of which in the clinker ranges between 45–60 % (50 % in average), and later from belite (2cao ∙ sio2), the content of which ranges between 20–30 % : 2(3cao ∙ sio2) + 6h2o = 3cao ∙ 2sio2 ∙ 3h2o + 3ca(oh)2, 2(2cao ∙ sio2) + 4h2o = 3cao ∙ 2sio2 ∙ 3h2o + ca(oh)2. during concrete settling, while the surface of concrete is moisturized, cement hydration degree reaches 0,5–0,6. reactive pozzolanic admixtures, i.e. reactive sio2, bind the released portlandite into hydrosilicates of higher or lower basicity: ca(oh)2 + sio2 = cao ∙ sio2 ∙ h2o for this reaction to occur the content of reactive [sio2]act must be [sio2]akt = 60/74 ca(oh)2 = 0.81 ca(oh)2 (1) the amount of portlandite ca(oh)2 in concrete formed from alite, which accounts for ½ of clinker cement (c) weight, is: c.0.32c0.650.5 c oh32sio3cao ca(oh)3 5.0ca(oh) 22 2 2 ⋅=⋅⋅= =⋅ ⋅⋅ ⋅= c.0.16c32.06.081.0]sio[ act 2 ⋅=⋅⋅⋅= c. 100 16.0 100 ][sio p act 2 ⋅== xx . 16.0 100 c16.0 ccp cb + ⋅ =−= x b b (2) it is recommended to bind approximately 0,5–0,7 (0,6 in average) content of portlandite with reactive pozzolans to avoid the consequences if of alkali reaction with reactive aggregates, i.e. volume deformations. therefore the content of [sio2]act should be: c.0.32c0.650.5 c oh32sio3cao ca(oh)3 5.0ca(oh) 22 2 2 ⋅=⋅⋅= =⋅ ⋅⋅ ⋅= c.0.16c32.06.081.0]sio[ act 2 ⋅=⋅⋅⋅= c. 100 16.0 100 ][sio p act 2 ⋅== xx . 16.0 100 c16.0 ccp cb + ⋅ =−= x b b (3) the percentage concentration (x) of [sio2]act in pozzolanic admixtures must be known: c.0.32c0.650.5 c oh32sio3cao ca(oh)3 5.0ca(oh) 22 2 2 ⋅=⋅⋅= =⋅ ⋅⋅ ⋅= c.0.16c32.06.081.0]sio[ act 2 ⋅=⋅⋅⋅= c. 100 16.0 100 ][sio p act 2 ⋅== xx . 16.0 100 c16.0 ccp cb + ⋅ =−= x b b (4) the content of pozzolanic admixtures in relation to the base quantity of the cement cb to produce the concrete of required strength is calculated from the equation: c.0.32c0.650.5 c oh32sio3cao ca(oh)3 5.0ca(oh) 22 2 2 ⋅=⋅⋅= =⋅ ⋅⋅ ⋅= c.0.16c32.06.081.0]sio[ act 2 ⋅= ⋅⋅⋅= c. 100 16.0 100 ][sio p act 2 ⋅== xx . 16.0 100 c16.0 ccp cb + ⋅ =−= x b b (5) using the data of fly ash given in table 2 in equation 5, we calculate that 25,8 wt % of fly ash must be added to neutralize the alkali – silica reaction of concrete. 5. results the specimens were measured after 3, 6 and 9 months following the beginning of the experiment. after the measuring the volumetric strains were calculated. the effect of fly ash used as the mineral admixture was determined by analysing the relation between the average volumetric strain and the content of fly ash in concrete mix in the batch of specimens with the same content of the fly ash. fig. 4. average volumetric strains of specimens after 3 months 38 measuring results obtained 3 month after the beginning of the experiment (fig. 4) showed that in general the biggest deformations and expansion of the volume of specimens was observed in specimens with the aggregate from kvesai quarry. the volumetric strain in specimens made of concrete mix with aggregate from this quarry and 0 % of fly ash was 0,0220, i.e. several times higher compared to specimens of the same composition with aggregates from rizgonys and zatyšiai quarries. in some cases even contraction of the prism volume was observed in specimens with aggregates from the latter quarries. the volume decreases due to concrete contraction during curing. the volumetric strains in all specimens after 3 months of curing were very low and the change in size did not depend on the fly ash content in the mix. this implies that after 3 months of curing in sodium hydroxide solution of +20 0c, the alkali – silica reaction did not occur due to low temperature of the solution and/or because the specimens were not saturated with na+ ions that did not increase the total alkali content in the mix. after 6 months of soaking in naoh solution much higher deformations of specimens were observed (fig. 5). from figure 5 we may see that, similar to the results obtained after 3 months of curing, the biggest volumetric strains were observed in specimens with aggregates from kvesai quarry. the only difference was that the strains were more regular. this is evidenced by the resulting functional relationship between the deformations and fly ash content. the analysis of obtained data showed that the empirical coefficient of fly ash content and the average volumetric strains in specimens with aggregates from kvesai quarry was 0.9005, and the correlation coefficient was 0.9489. it should be also noted that already after 6 months of curing the volumetric strains in specimens with the aggregate from kvesai quarry (0,0395 %) have almost reached the limit of 0,04 %. this limit is established by the canadian standards association (csa) (shehata, thomas 2002). volumetric strains are several times lower in specimens with the same aggregate but higher content of fly ash (25 %, 30 %); therefore it is clear that mineral admixture, active fly ash is our case, has a positive effect. such a reaction in specimens with aggregate from this quarry could have been influenced by several factors. firstly, the limestone caco3 present in the aggregate could have been bound by non-crystalline and/or microcrystalline sio2, and thus the quartz present in the aggregate could have been deformed and cause the alkali – silica reaction. according to the obtained results we may see that alkali – silica reaction is the strongest in these specimens. most probably it is because of the presence of more reactive rocks than in the aggregates from rizgonys or zatyšiai quarries. alkali – silica reaction processes in specimens with aggregates from zatyšiai quarries are weaker. volumetric strains in these specimens are much lower and less dependent on the content of mineral admixture. as seen from the x-ray images, the aggregate from this quarry mostly contains sio2 with crystalline matrix. the volumetric strains after 6 months of curing are the lowest in specimens containing the aggregate from rizgonys quarry. they do not depend on the content of fly ash either. no alkali – silica reaction was observed in these specimens after 6 months of curing (fig. 5). fig. 5. average deformations after 6 months volumetric strains observed after 6 months in specimens with chert aggregate are not significant compared to specimens with the aggregate from kvesai quarry (fig. 5); however a strong relationship between the volumetric strain and the content of fly ash is observed. in these specimens alkali – silica reaction (fig. 6) is much more prominent compared to specimens made of other concrete mixes. figure 6 illustrates a pressed out granule of the aggregate, an indication of alkali – silica reaction. such behaviour was observed in the majority of specimens with reactive chert aggregate. along with the pressed out granules we may see a cracking pattern (fig. 7). fig. 6. a granule of aggregate pressed outside the specimen surface visual changes were observed even in specimens with 25 % of fly ash; however no apparent changes were seen in specimens with 30 % of fly ash. therefore, we may state that 30 % of mineral admixture (fly ash) is enough to prevent the alkali – silica reaction even in a very aggressive environment, which in our case was 1 n naoh solution of 20 0c, when the aggregate is reactive chert. 39 fig. 7. a visible cracking pattern in the specimen with rocks after 6 months in alkaline environment generally, the alkali – silica reaction was the most significant in the specimens with chert aggregate after 6–9 months (fig. 8). the deformation of these specimens was the most prominent in the said curing period. figures 8 and 9 illustrate that 30 % of fly ash is sufficient to prevent the alkali – silica reaction even when a very aggressive aggregate is used. fig. 8. average volumetric strains in specimens after 9 months fig. 9. relationship between volumetric strains and fly ash content using the volumetric strain measurement results at 9 months and in view of different fly ash content, reliable firstdegree equations were developed (fig. 9), where correlation coefficients, subject to the type of aggregate, change in the interval 0,71… 0,91. the effect of alkali – silica reaction was visually seen in the last stage of the experiment. almost all specimens, where chert was used as the coarse aggregate and cement was replaced by 25 % and 0 % of fly ash, have cracked, granules of the aggregate were pressed out from the surface, various swellings, which were not seen before, were observed on the sides of the prisms (fig. 10). fig. 10. a specimen after 9 months curing in aggressive environment it should be also noted, that visual symptoms of expansion were also observed in specimens containing the aggregate from kvesai quarry and 0 % of fly ash. specimens of this batch also bore a slight cracking pattern. these specimens demonstrated the biggest volumetric strains after 3 and 6 months. 6. discussion cracking of concrete structure, due to asr, is caused by the expansion of calcium hydrosilicate gel – a product of a chemical reaction (asr) between the reactive silica contained in the aggregates and the alkalis within the cement paste. active mineral admixtures, such as pozzolans, chert, silica-fume, fly ash, slag etc. help to mitigate the negative effect of asr. the aim of using the said mineral admixtures is to bind the alkalis within the cement paste before the final setting of concrete and to prevent the degradation resulting from the expansion of silica gel. asr is actively investigated and mitigation methods to prevent asr are being developed. researchers and engineers working in this field face numerous difficulties. they try to find the most optimal and universal method to prevent the alkali – silica reaction. another important issue is to find out how the gel, being a liquid substance, can damage such a solid material as concrete. a number of hypotheses have been suggested by the researchers; however the phenomenon has not been fully investigated. in cases when very reactive aggregates are used, 50 % of cement have to be replaced by fly-ash or slag to control the asr. unfortunately, such a high content of pozzolanic admixtures has a negative effect on concrete strength. adding of several types of admixtures, for instance fly ash with silica-fume, help to avoid the negative outcomes. the 40 proven synergic effect of the said substances enables to reduce the content of the admixtures used in the cement mix. the studies of asr are very important. the negative effect of asr can manifest in spite of preventive measures. for this reason further investigations in this field are necessary because there are still many unanswered questions. answers must be found in order to successfully mitigate the damage of asr. 7. conclusions specimens where examined every 3 month and further findings where observed. no significant symptoms of asr were noticed in the first three months of the experiment. after 6 months the following asr indications were observed: ▪ expansions of the tested prisms; ▪ visually apparent cracking pattern on the specimen surface; ▪ pressed out granules of the aggregate on the specimen surface. after 9 months of the experiment the asr indications were more apparent. the available data suggest the process of alkali – silica reaction in the specimens. the relationship between the average volumetric strain and the fly ash content became apparent after 6, while at three months since the beginning of the experiment such relationship was not present. the analysis of experimental data shows that deformations are less significant in specimens with a higher content of fly ash used as an active mineral admixture. the same trend was observed in specimens of all types of concrete mix, except for the specimens with the aggregate from rizgonys quarry after 6 months in aggressive environment. after 9 months, however, minor but typical deformations were also seen in specimens with the said aggregate. indications of alkali – silica reaction were especially noticeable in specimens with the aggregate from kvesai quarry, where the most significant deformations in prisms with 0 % fly ash reached 0,0395 %. the deformations had the highest functional dependency on the fly ash content in the mix, the correlation coefficient r = 0,9489. indication of alkali – silica reaction, namely pressed out granules of the aggregate and cracking pattern was also observed after 6 months in specimens with very reactive aggregate (chert). these specimens demonstrated big deformations at 9 months since the beginning of the experiment. according to all criteria, the strongest manifestation of alkali – silica reaction was observed in specimens with carbonate chert. 30 % of fly ash in concrete mix was enough to stop the alkali – silica reaction. references standard test method for determination of length change of concrete due to alkali-silica reaction astm c 1293. balandis, a. et al. 2006 . 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ash concrete incorporating nano – sio2, cement and concrete research 34 (6): p. 1043-1049 doi: 10.1016/j.cemconres.2003.11.013. lingård, j. et al. 2011 . alkali-silica reactions (asr): literature review on parametres influencing laboratory perfomance testing, cement and concrete research 42 (2): p. 223–243 doi: 10.1016/j.cemconres.2011.10.004. lst 1974:2012 olba, k. h. 2008. specifying fly ash for use in concrete. silver spring: nrmca, http://www.nrmca.org/research/cif%20 spring%2008%20fly%20ash.pdf> 41 rilem tc 191-arp shafaatian, s. m. h et al. 2013. how does fly ash mitigate alkalisilica reaction (asr) in accelerated mortar bar test?, cement & concrete research 37: p. 143–153 doi: 10.1016/j.cemconcomp.2012.11.004 shehata, m. h., thomas. m. d. a., 2002. use of ternary blends containing silica fume and fly ash to suppress expansion due to alkali–silica reaction in concrete, cement and concrete research volume 32, issue 3, march 2002, pages 341–349. doi: 10.1016/s0008-8846(01)00680-9 skripkiūnas, g. 2007. statybinių konglomeratų struktūra ir savybės. kaunas: technologija: 334 p. isbn 978-9955-686-50-7. thomas, m. d. et al. 2010. effect of fly ash on the expantion of concrete due to alkali – silica reaction – exposure site studines, cement and concrete composites 33 (3): p. 359– 367 doi: 10.1016/j.cemconcomp.2010.11.006 turanli, l. et al. 2003. use of ground clay brick as puzzolanic material to reduce the alkali-silica reaction, cement and concrete research 33 (10) 1539-1542 doi: 10.1016/s00088846(03)00101-7. vektatris, b.; vilkas, v. 2006. betono tvarumas. betono sulfatinė ir šarminė korozija, atsparumas šalčiui ir karbonizacijai. tyrimai ir prevencinės priemonės [monografija]. kaunas: technologija, prieiga per internetą: < www. balkonurenovacija.lt/betono_korozija.pdf>. received 2014 02 04 accepted after revision 2014 02 24 audrius grinys – doctor of technology sciences, assoc. professor of the department of building materials at kaunas university of technology. main research area: ready mix and precast concrete technology, chemical additive of concrete, concrete deformability, concrete strength and utilization of waste materials. address: studentų g. 48, lt–51367 kaunas, lithuania. tel.: +37065690441 e-mail: audrius.grinys@ktu.lt vytautas bocullo – master graduated degree of the department of building materials at kaunas university of technology. main research area: concrete asr. address: studentų g. 48, lt–51367 kaunas, lithuania. tel.: +37068248654 e-mail: donbocullo@gmail.com algirdas gumuliauskas – department of building materials at kaunas university of technology. main research area: concrete asr. address: studentų g. 48, lt–51367 kaunas, lithuania. tel.: +37061651042 e-mail: agum@takas.lt 19 darnioji architektūra ir statyba 2013. no. 3(4) journal of sustainable architecture and civil engineering issn 2029–9990 landscape protection and management guidelines for roads: problems and amendments for lithuanian legal acts irina matijošaitienė1*, ona samuchovienė2 1*kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management, studentu st. 48, lt-51367 kaunas, lithuania 2uab “infraplanas”, k. donelaicio st. 55-2, lt-44245 kaunas, lithuania *corresponding author: irivarl@yahoo.com http://dx.doi.org/10.5755/j01.sace.3.4.4779 in 2011 the ministry of environment of the republic of lithuania ordered to prepare the “landscape protection and management guidelines for roads and railways”. integration of the trends of the politics of lithuanian republic and the requirements of legislation, which is related to landscape protection and management, into the road development system is only a part of all the tasks of these guidelines. this part, including the analysis of lithuanian legal acts, identification of their problems and proposal of amendments, is presented in this paper. as a result, the amendments were proposed for lithuanian legal acts regarding the road landscape evaluation methodology, visual impact of roads on the environment, road signs, advertising regulation and planting near the roads. keywords: legal act, legislation, road, road landscape. 1. introduction in the lithuanian landscape according to the importance roads are in the second place after the rivers and streams: it is estimated that there are approximately 22.2 thousand kilometers of rivers and streams which total about 76.8 thousand kilometers in length (aplinkos … 2012); the total length of roads and streets equals to 82 thousand kilometers, where 21.3 thousand kilometers are the roads of state importance and more than 60 thousand kilometers are the roads and streets of local importance (municipalities) (lietuvos … 2012b). due to this reason, the sustainable road designing and maintenance are significant for the promotion of our country image, natural and cultural heritage, preservation of bio-diversity, protection of landscape identity and value. the project “landscape guidelines for lithuanian roads and railway” is being implemented in 2011-2013 by the ministry of environment of the republic of lithuania. the guidelines “landscape protection and management guidelines for roads and railways” in the frame of the project are prepared by specialists of jsc “infraplanas” and other scientific institutions, as well as the authors of the paper. the guidelines are developed in order to increase the understanding of society, private institutions and authorities about meaning, values, role and changes of state roads. the project is going to the end, and there are the main landscape designing principles which should be followed when planning, designing, building, reconstructing or mending lithuanian state roads formulated. guidelines are going to be published at the end of 2013 year and intended for representatives of authorities (municipality, environmental protection and cultural heritage specialists, designers, engineers, builders and managers) in order to find easier decisions when adjusting requirements of traffic safety and designing with landscape value protection and improvement, that the road would be both comfortable to use and picturesque to see. when preparing the guidelines and trying to integrate requirements of lithuanian landscape policy and other landscape protection and management legislations to road development system the analysis of lithuanian legal acts has been performed, main problems have been formulated, conflict decisions and amendments of legal acts have been introduced. the offers for legal acts and the arranged guidelines have to ensure development of identity of lithuania and its ethnographic regions, single landscape units, protection and multiplying of ecological and aesthetics values, expedient designing of road landscape and general improvement of lithuanian image when constructing, rebuilding and maintaining the roads. 2. analysis and proposals in accordance with the european convention on landscape (europos … 2000), every country seeking to implement the landscape policy, undertakes to adopt the legal 20 acts designed for protection, management and/or planning of landscape. presently, the main legal acts for landscape protection are the documents of territorial planning, assessment of the effect on the environment and other environmental legal acts, cultural heritage and international legal acts. this structure is supplemented by the road design and planning legal acts with reference to landscape, relief, vegetation, etc. the guidelines “landscape protection and management guidelines for roads and railways” is the first strategic document for protection of the landscape of roads and railways in lithuania. according to the legal acts of the republic of lithuania in effect today, the building of motorways and highways, also, of roads with four or more lanes or reconstruction of roads with fewer than four lanes, by building four or more lanes (when building or reconstructing a continuous section of 10 km or longer) is included into the list of types of the planned economic activity, the impact of which on the environment is to be assessed. the selection procedure for the environmental impact assessment (eia) must be carried out in building regional roads longer than 2 km and those having four or more lanes, also, in reconstructing the roads by building four or more lanes (when building or reconstructing the road shorter than 10 km, but longer than 2 km long continuous route). this paper represents the review of legal acts grouped according to themes, and the suggestions for their amendments. the suggestions are only preliminary requiring thorough analysis and motivated substantiation. their final formulation will be presented only after preparing the landscape guidelines. 2.1. legal acts related to territorial planning in these legal acts the aims to create preconditions for maintaining or reconstructing landscape ecological equilibrium are specified (lietuvos … 2004b). in addition, they contain the cases when the private land can be taken for public purposes followed by compensation for the property. the acts provide for the motivated substantiation of the taking of land (lietuvos … 2011a) and for the ways of compensation (lietuvos … 2005b). the general plans do not deal with the issues of aesthetic visual quality of the roads and their landscape. the master plan of the territory of the republic of lithuania (lietuvos … 2002) promotes the expansion and improvement of the transit roads for tourist mobility which, for the most part, coincide with the main motorways, and specialized tourist routes. in addition, the planned urban integration axes are also provided. the recreation sector identifies the development of educational tourism and recreation in nature as one of the priorities. but tourist attraction and recreation objects are connected by the roads of different categories which are supposed to be representative of the country, promoting tourism and convenient for the users; the roadscape should be attractive and not boring. the main priority in the structure of transportation and communication infrastructure is given to the development of automobile transport. the master plans of vilnius city (vilniaus … 2007), kaunas county (kauno … 2009) and klaipėda region municipality (klaipėdos … 2005) provide for the new communication routes and building of the deficient junctions for motorways. the problem: nonexistence of landscape management strategy for the sideways and in the neighborhood of railway lines. a too complicated procedure of taking land for public purposes (e.g. for landscape management near the roads and railways) is applied. the proposed amendments: regarding the legal acts related to territorial planning, integration of landscape through master plans and taking of land for public purposes is proposed. the order of the minister of the environment of the republic of lithuania „on the approval of the rules for preparation of the master plan of the county‘s territory, for the master plan of the municipality territory and for the master plans of the cities and towns“ (lietuvos ... 2004a) is proposed to be supplemented by the following proposals: to develop vegetation along the roads, to establish the newly designed vegetation zones on the roadsides, to mark not only planned, reserved and taken territories for the communication systems, but also for the related environment, on the drawings of the communication and engineering infrastructures. this proposal can also serve as the tool for placing responsibility for vegetation, so that the proposal is applied not only for the road manager, whose powers are limited by the traffic safety requirements and the lack of free land nearby the roads. these requirements can be also applied for the owners of logistics, commercial and other territories, whose plots border on the roadband, and whose development change the highway environment dramatically. even though according to the lithuanian law on roads (lietuvos ... 1995), vegetation is attributed to the „concept of the road“, it is a complicated task to take the land from the owners for the purpose of vegetation, because to this effect, the substantiation of taking of land must be provided (following the decision of the government of lithuania „on the submission of the request to take the land for public purposes and the rules of investigation of the request and the preparation of projects for taking the land for public purposes and the approval of the rules for its implementation“ (lietuvos ... 2005b)). therefore, there exixts the possibility to propose the amendment of the law on land (lietuvos ... 2004c), so that it can be applied to the design of landscape along the roads. the order of the lr communication minister and lr environment minister „on the approval of the rules of preparation of special plans for means of communication“ (lietuvos ... 2006a) is proposed to be supplemented by the requirement that in conducting the evaluation of the impact on the environment, special attention should be given to the impact of communication infrastructure on the environment, also, in the stage of the analysis of the current condition, visual resources of the roaside landscape should be evaluated and the possible utilization of these resources should be proposed; the proposals for roadscape management should be submitted at the implementation stage. in preparing the detailed plans at the stage of the analysis of the present condition, visual quality of the lanscape should be evaluated. 21 2.2. legal acts related to the issues of environmental impact assessment these legal acts clearly define the concept of landscape and its management for the purpose of economic activity, including building of the planned new roads, (lietuvos ... 2005a), the scope of evaluation of the impact on the landscape, the impact reduction strategy in selecting the measures (lietuvos ... 2006b), also, they provide for the ecological equilibrium of the landscape, landscape geoecological equilibrium, protection of landscape diversity, its uniqueness and specific features; the legal acts also provide for the adaptation of the complexes of cultural landscape and its objects for exposure to the visitors (lietuvos ... 2001a). they regulate public relations in the area of environment protection, set the main rights and responsibilities of legal and physical entities towards the preservation of biological diversity, ecosystems and landscape typical to the lithuanian republic, thus, ensuring healthy and clean environment, sustainable utilization of natural resoures within the territorial waters, continental shelf and economic zones (lietuvos ... 2011b). the problem: nonexistence of the roadscape assessment methodology; inadequate certainty of the qualification of the organizers of the eia. the proposed amendments: presently, in accordance with the law on the assessment of the planned economic activity on the environment (lietuvos … 2005a) the organizer of the eia can be any specialist with a scientific degree, thus, all parts of the assessment of the effect on the environment can be prepared by a single specialist. accordingly, the quality of the assessment of different parts is inadequate and the proposed protection measures often lack competence. consequently, the proposal is to set detailed rules related to education and qualification requirements for the person, including the environment evaluator, in preparing each part of the eia. the order of the lr environment minister “on the approval of the preparation of provisions for the program and report of the assessment of the impact on the environment” (lietuvos … 2006b) delivers inadequate instructions on landscape assessment which have influence on differing and frequently incompetent assessment of the landscape. for this reason, there is a proposal to work out methodology in which detailed criteria requiring obligatory assessment are set. the following are the possible assessment criteria: vividness, integrity, diversity, naturalness, picturesqueness, infrequency, cultural changes, as well as relief, vegetation, water, colors, exceptionality, also, such features as recreational, historical, informative, scientific, geological, natural, cultural, ethnic or rich in biological diversity. 2.3. legal acts related to road design these legal acts give but a very general description of roundabouts and vegetation of the surroundings (lietuvos … 2012a). the vgtu road research institute has prepared (not approved yet) a new road division study “the analysis of the purpose of the road network element and preparation of development plan” which identifies the roads recommended to be widened, unchanged or even narrowed. “the rules for highways and motorways design” (rhmd 13) being prepared by the same author, are going to present the regulations of incorporation of roads in the landscape with regard to the relief, relation to the water pools, as well as other environmental aspects. currently, technical regulation for roads ktr 1.01:2008 (lietuvos … 2008c) describing roads and design materials, parameters (profiles, safety requirements, recommended distances for vegetation, etc.) is in force. the problem: insufficient regulation of landscape protection and management, insufficient amount of proposals for design including the design of roadscape and environmental measures, implementation and maintenance. the proposed amendments: the first edition of rhmd 13 lacks environment evaluation and protection measures, including landscape protection, analysis of the procedures; therefore, there is a proposal to specify road evaluation procedures in regard of the classification and nature of construction works. in addition, there is a proposal for the lithuanian road administration to supplement the existing recommendations for environmental protection measures with the new document “landscape protection and management apr-kat 13”. this document should specify detailed recommendations for road design. for this purpose the design manual for roads and bridges (design … 2001) issued by highway agency of great britain is recommended to use. 2.4. legal acts related to road signs and proposals for the system of road information the resolution of the government of the republic of lithuania “on the approval of traffic rules regulations” (lietuvos … 2008e) lacks provisions on the information system for natural and cultural values. the problem: the roadside information system lacks consistency, and in some places there is an insufficient number of road signs. the proposed amendments: this legal act is to be supplemented by providing for the creation of new road signs to inform on the natural and cultural values within the territory of lithuania. in addition, comprehensive amendment of the act providing for the reorganization of the roadside information system which would cover consistent development and adequate and sufficient location of road signs is necessary. currently, the present information system is under study, therefore, new road signs have not been introduced and the issue has not been thoroughly analyzed yet. 2.5. the legal acts related to the regulation of the outside advertising these legal acts do not sufficiently regulate the location, exterior and siting of advertising hoardings at the roadsides (lietuvos … 1992; lietuvos … 2000; lietuvos … 2001b). the problem: insufficient regulation of advertising hoardings at the roadsides. the proposed amendments: specific conditions for using land and forests (lietuvos … 1992) provide for prohibition of advertising hoarding solely in the road 22 protection zones, but their location outside the zones is not regulated (e.g. abundance of different advertising hoardings along the a1 road vilnius-kaunas). consequently, there is a proposal to provide for higher requirements for visual quality of the landscape, leaving the existing road protection zones without introduction of any changes. also, the proposal is to establish practical measures for regulating the installation of advertising hoardings in compliance with the amendments of the lr law on advertising (lietuvos … 2001b), since according to this law the permissions for the installation of the hoardings are issued by relevant municipalities which operate instruments for restrictions on the location and type of advertisements. there is a recommendation to change the provisions on visual pollution caused by advertising hoardings. 2.6. legal acts related to vegetation these legal acts provide for the responsibilities of the communication ministry and give definitions for vegetation and its management along the motorways (lietuvos … 2007). they set the requirements for vegetation along the roads in the territories of natural frame (lietuvos … 2010c) and describe cases when transplanting of trees and bushes to be protected is carried out (lietuvos … 2008a). following the lr government resolution “on the approval of the list of the criteria according to which trees and shrubs growing in the non-forest land are assigned to those to be protected and on the assignment of trees and shrubs to those to be protected” (lietuvos … 2008d), the road lane can be not nearer than 1 m from the side of the trench, padding or excavation (i.e. it can be farther away than 1 m), therefore, this lane area covers practically all roadside alleys, etc. the lr communication ministry’s order “on the approval of the description of procedure for cutting and pruning of trees and shrubs growing along the roadside of the state motorways and in the protection zones of railways and their equipment, possibly causing danger for safe traffic” (lietuvos … 2008b) instructs that for cutting of trees and shrubs in the lanes of the road of state importance the permission is not required. it is in these places that the removal of vegetation along the roads of state or local importance is carried out to prevent obstruction. point 33.3 of the order of the lr environment minister “on the approval of the regulation rules for keeping trees and shrubs, water pools in the vegetation zones, lawns and flowerbeds” limits the height of tree crowns, which causes problems for lorries, because they can damage them through breaking branches. the problem: some of legal acts protect trees, others issue permissions for cutting them down, which leads to the absence of regulation to secure trees and plants by means of speed limit or partitions in the most dangerous sections. the proposed amendments: there is a proposal to supplement the lr government’s resolution “on the approval of the list of the criteria according to which trees and shrubs growing in the non-forest land are assigned to those to be protected and the assignment of trees and shrubs for those to be protected” (lietuvos … 2008d) in the following way: the alleys, according to regions, etc. are to be assigned to those to be protected by recommending to build partitions for road safety. not all the alleys are to be selected, but only those which are the most valuable and so far unprotected. the lr communication ministry’s order “on the approval of the procedure of pruning and cutting of trees and shrubs growing along the roads of state importance and railways and their constructions in the protection zones which threaten traffic safety (lietuvos … 2008b)” should be basically amended due to the conflict described in section 2. there is also a proposal to apply these requirements for the regional roads and roads of local importance. the lr environment minister’s order “on the approval of the procedure of cutting, transplanting or other kind of removal of trees and bushes to be protected, of execution of and the issue of permissions for these works and compensation for the value of the removed trees and shrubs” (lietuvos … 2008a) is preliminarily proposed to be supplemented in the following way: if the trees to be cut down or transplanted are too big, it is appropriate to replant them by trees and shrubs of the same species of trees and shrubs. replanting should be done with trees of the cross-section not smaller than 10 cm. the distance from the roadside and the way of replanting trees and shrubs should be predicted in advance (so that construction machines and mechanisms can move along without obstruction). however, there is one essential drawback of this proposal: if there emerges the need to take some private land for replanting vegetation, this will not be possible until the project of taking of land for public purposes is implemented. after taking the land, construction/ reconstruction works start immediately, and it is only after that the planting of trees is possible. from the order of the lr environment ministry “on the amendment of the approval of the provisions of the natural framework (carcass)” (lietuvos … 2010c) point 6.1., the word “sanitary” should be eliminated, because the road sanitary protection zones do not exist any longer. in addition, there is no recommendation to plant vegetation on the roadsides within the territory of natural carcass: if the speed is big, the zone of 3 – 15 meters at the minimum from the side of the road lane, according to the safety requirements, should be left free from vegetation. besides, vegetation is not recommended along the local communication roads which are not long (up to 1 km) and are designed for taking agricultural machines to the field or back to the farm, i.e. in the open agricultural territories. 2.7. planning recommendations the lithuanian road administration under the ministry of communication issued “recommendations for environmental tools for design, implementation and maintenance (protection of biological diversity)” in 2010 (lietuvos … 2010a). this is one of a few documents describing some of the roadscape design aspects. the recommendations describe the selection of the route and its longitudinal profile, the adaptation of bridges and viaducts for migration of wild animals and their adjustment to the landscape. the document gives a detailed description of the selection of landscape elements, their location with regard to the road or natural elements, their materials, color solutions, selection of type, parameters and materials of fences and enclosure borders, selection of double-leaf gates and horizontal barriers, installation of single-leaf gates and ramps, advantages and disadvantages. 23 “the recommendations for environmental tools for design, implementation and maintenance (traffic noise reduction)” (lietuvos … 2010b) say that the measure for reduction of traffic – caused noise is selected on the base of several criteria , including aesthetics, in accordance with the criteria of landscape, public safety, etc. the selection of route and preparation of practical solutions for spatial design, selection of partitions and noise reduction installations to avoid negative visual effect on the landscape are thoroughly described. the proposals for installation of wooden, brick, concrete, metal, transparent and plastic noise gates in the urbanized, suburban, rural and out-of-town environment are submitted. a detailed description of the architectural design of noise gates is provided to harmonize the gate with the environment. to achieve the latter aim, it is recommended to follow two essential principles of aesthetic combination, i.e. stylistic integrity of the structure and the landscape. the recommendations for the construction of mounds relating them to the visual quality of the landscape, the principles of vegetation and its assortment of the roadside are provided. 3. discussion lithuanian legal acts contain the following provision: the council’s directives bind the member states to carry out a comprehensive evaluation of direct or indirect impact on the landscape, however, concrete actions and methods are not specified, thus, regarding them the responsibility of the member state in accordance with the legislation of that state. it can be stated that road designing in the lithuanian legal acts is carried out based on documents of territorial planning, environmental impact assessment and other environmental legal acts, legal acts of cultural heritage, also, on other specific road designing and planning legal acts where landscape is involved (relief, vegetation, etc.). however, these documents lack legal and practical compatibility between roadscape and traffic safety, e.g. cutting down of trees at the roadsides, which in some cases is necessary for the sake of safety, has a negative effect on the aesthetic quality of the landscape. the review of the relevant lithuanian legal acts showed that legal acts regulating landscape protection, fail to ensure sustainable road development, therefore, an integrated publication to present the main principles of incorporation of roads into the landscape is necessary. the publications of this type (planning manuals, guidelines) are available in other foreign countries. their experience can be a good example in developing landscape protection and management guidelines for lithuanian roads. none of all lithuanian legal acts require mandatory evaluation of the aesthetic visual impact of the road on the environment. the analysis of the lithuanian legal acts showed that: ▪ there is no strategy of road landscape management in lithuania; the procedure of taking land for public needs (for landscape management near the roads) is complicated; ▪ the methodology for road landscape evaluation is non-existing, besides, the qualification of eia developers is insufficient; ▪ the regulation of landscape protection and management is insufficient. in addition, there is a lack of proposals for design, realization and maintenance of highway landscape and environment implements; ▪ the integrated and comprehensive information system (signs) covering natural and cultural values, is nonexistent; ▪ there is a need for a more exacting regulation for building of advertising stands along the highways; ▪ there are contradictions between the existing legal acts: some acts are meant to protect trees, others issue permissions for cutting them near the roads, while the problem could be solved by limiting the speed or by railing off the most dangerous sections of the road, thus, saving the roadside vegetation. 4. conclusions the preliminary proposals submitted for improvement of the lithuanian legislation can regulate roadscape design through master plans and taking of land for public purposes. the essential proposals are the following: ▪ to work out the road landscape evaluation methodology involving detailed criteria of the obligatory assessment of visual impact of the road on the environment. the qualification and education of the developer of each part of the eia should be specifically regulated; ▪ a document with specified recommendations for the design of the lithuanian road landscape should be prepared; ▪ in carrying out the evaluation of the effect on the environment, visual effect of the communication infrastructure on the environment should be taken into consideration, visual resources of the roadside landscape should be evaluated, the possibilities for utilization of these resources and detailed proposals for landscape management should be offered; ▪ it is necessary to analyze the existing system of road signs and, if necessary, it should be expanded to an integral and easily understood system with the information on the cultural values in lithuania; ▪ the requirements for visual quality of the landscape should be provided, the provisions for the visual pollution caused by advertising billboards should be amended, the amendments of the lr law on advertising on the regulation of practical installation of advertising billboards should be provided; ▪ it is highly recommended to preserve the most 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(2000. lietuvos respublikos reklamos įstatymas. valstybės žinios, 2000.07.31, nr. 641937. lietuvos respublikos seimas. 1995. lietuvos respublikos kelių įstatymas. valstybės žinios, 1995.05.26, nr. 44-1076. lietuvos respublikos vyriausybė. 1992. nutarimas nr. 343 „dėl specialiųjų žemės ir miško naudojimo sąlygų“. valstybės žinios, 1992.05.12, nr. 22-652. vilniaus miesto bendrasis planas iki 2015 m. 2007. available at: http://www.vilnius.lt/bplanas/index.php?mid=65&lang=lt (accessed 15 march 2010). received 2013 07 13 accepted after revision 2013 07 29 25 irina matijošaitienė – associated professor at kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management. main research areas: urban and road landscape, space syntax, kansei engineering, hedonomics, ergonomics, statistics. address: studentu st. 48, lt-51367 kaunas, lithuania. tel.: +370 37 300456 e-mail: irivarl@yahoo.com, irina.matijosaitiene@ktu.lt ona samuchovienė – environmental senior epecialist, master of geography, joint stock company “infraplanas”. main research area: environmental impact assessment, assessment of roads, railways, wind power plants impact on landscape and land use. address: k. donelaičio st. 55-2, lt-44245 kaunas, lithuania. tel.: +370 37 407548 e-mail: o.samuchoviene@infraplanas.lt 233 journal of sustainable architecture and civil engineering 2023/1/32 plywood panel with uhmw polyethylene board ballistic resistance received 2022/11/22 accepted after revision 2023/04/21 plywood panel with uhmw polyethylene board ballistic resistance jsace 1/32 elina barone*, edvins velicko, baiba gaujena, martins vilnitis riga technical university, faculty of civil engineering, department of building technology, kipsalas street 6a, riga, lv-1048, latvia *corresponding author: elina.barone@rtu.lv https://doi.org/10.5755/j01.sace.32.1.32822 journal of sustainable architecture and civil engineering vol. 1 / no. 32 / 2023 pp. 233-243 doi 10.5755/j01.sace.32.1.32822 abstract introduction in this study, bullet-proof building panels are investigated. the aim of this work is to verify whether the polyethylene-plywood panels withstand frontal impact with high-speed projectiles. ultra-high molecular weight polyethylene (uhmwpe) is a promising ballistic material due to its favorable properties – significant impact toughness and a high strength-to-weight ratio, meantime it is lightweight. by setting different parameters such as laminated plywood width and various uwhmpe facade layers, the protective effect of the panels and their performance characteristics are discussed using a 9 mm caliber handgun glock 17 luger bullets. the results show positive results – 3 of 4 combinations resist the bullet. the board with an arrangement of 2x32 cm laminated plywood outside and uhmwpe material inside the room captures 4 bullets; the bullets pass through the plywood layer and stop in the polyethylene. the experiment also tested individual uhmwpe panels at 2 different thicknesses to monitor the damage to the material. the results of this study will be useful in designing ballistic panels for buildings like unclassified buildings (army headquarters, safe rooms) from small arms weapons also for individual use. keywords: ballistic, composite panels, plywood, shooting range, uhmwpe. ballistic defense continues to be one of the important areas for research and development in the civilian and military areas. designing adequate protection for buildings and structures is complex due to the many technical requirements and factors that influence effectiveness. regardless of life expectancy, a unique parameter in the construction of all military facilities is the specifications related to the building’s force protection – the structure’s inherent ability to provide safety and security and customary conditions to the occupants and equipment inside. (borodinecs et al., 2019, 2022; sanborn, 2018) therefore, for relatively impact fragile civil buildings, wall reinforcement is significant. traditional explosion-proof walls usually use high-strength concrete or are equipped with many steel bars to achieve wall reinforcement. this method is complicated by high-cost construction and increases the structure’s weight. more importantly, it takes time to repair. (wu et al., 2021) for this reason, this paper proposes relatively light ultra-high molecular weight polyethylene uhmwpe material connected with laminated plywood. plywood combined with polyethylene is not yet widely used as a composite material, leading to scientific interest in using new materials but available in the market for ballistic defense. there are many studies regarding uhmwpe material and its response to ballistic effects. still, most of these studies are for body armor, not building materials. applying prefabricated building modules significantly reduces on-site installation time and allows correct material specification and energy simulation due to precise measurements. (borodinecs et al., 2017, 2019, 2020, 2022) journal of sustainable architecture and civil engineering 2023/1/32 234 the performance of uhmwpe in combination with plywood has not been investigated so far. the authors tested plywood for ballistic resistance (barone et al., 2022). both theoretical and experimental results showed that 3x28 mm plywood retained the bullet to a penetration depth of 64 mm and was the only bulletproof material compared to building materials such as spruce clt or pine logs. therefore, plywood was used as the uhmwpe layer variation in this experiment. even though ballistic testing of clt indicates that the material’s inherent penetration resistance is significantly more excellent than lumber and plywood that are commonly used in temporary military structures. (sanborn, 2018; sanborn et al., 2019) currently, wood is not assessed for the design of a protective system beyond use as a pre-detonation screen because of its low strength compared to steel and concrete. (sanborn, 2018). the general uhmwpe production process involves the fiber manufacture in a high-temperature gel-spinning process and then coated in resin, stacked crosswise to the desired thickness, and hot pressed. (sanborn, 2018; van dingenen, 1989) as commercially, the uhmwpe board is one of the most promising materials, researchers develop design and synthesis methods and specify the requirements for protection levels and zones. uhmwpe is a suitable material not only for light armor applications where high-velocity impacts are predominant (carrillo et al., 2011a; crouch, 2021; firouzi et al., 2022). the research on uhmwpe in composites has mainly been focused on anti-shrapnel penetration, and there is little research on its anti-blast performance. (wu et al., 2021) wu x. et al. researched uhmwpe-based material and found that there should be a certain distance between the protective plate and the wall to be protected in the actual situation. and they dispute the fire safety of this material. (ur rehman et al., 2021; wu et al., 2021) uhmwpe has properties such as low water absorption. the material is non-toxic, odorless, has good thermal insulation properties, has a simple chemical composition and structure, is chemically and radiatively neutral, has a low coefficient of friction and resistance to abrasion and wear, and has a significant impact on toughness (wood w, 2012). it has a low density (930–950 kg/m3), and it is lightweight (karmakar, 2022), which makes it the best material in terms of a high strengthto-weight ratio (karmakar, 2022; wood w, 2012). uhmwpe material has high energy dissipation capability due to the large deformation. due to its excellent impact resistance and low enough density, uhmwpe fiber has broad application potential in ballistic protection and material weight reduction. (cao et al., 2021) uhmwpe fiber name is dyneema sk60/cuben fiber is at present the strongest synthetic fiber in the world, being 10 times stronger than steel and 50% stronger than aramid fiber (tensile strength of 2.7 gpa). (dyneema® composite fabrics (dcf) and cuben fiber explained | hyperlite mountain gear, n.d.; van dingenen, 1989) however, compression and shear modulus will often be limited when using only dyneema fibers in a composite. (van dingenen, 1989) uhmwpe has shown higher energy absorption capacity at higher impact velocities than at lower velocities. (sanborn, 2018). the material used in the study is pe1000. it has a molecular weight of 5–9·106 g/mol, is tear and impact resistant, and remains flexible even at low temperatures – operating temperatures from – 250 °c to +80 °c. it is noise-absorbing and a suitable dielectric. however, uhmwpe is poorly used in the construction sector. polyethylene cannot be glued together, so mechanical joining or welding (only for certain types) must be used. (e-plastena.lv/polietilēns, n.d.) there are studies on the replacement of pile cushions with uhmwpe (tulatorn et al., 2015), uhmwpe beam study (attwood et al., 2016), and low-speed testing of uhmwpe beams (karthikeyan et al., 2013). k. sanborn comments that uhmwpe itself lacks the overall strength and stiffness for use as a structural panel (sanborn, 2018). the uhmwpe–plywood building panels are intended to be used alone or in combination for protection against small caliber and standard caliber projectiles or blast splinters, protecting against direct or accidental shots. cao et al. have studied that for a 20 mm uhmwpe laminate, the pen235 journal of sustainable architecture and civil engineering 2023/1/32 etration depth is approximately more than half the thickness of the laminate, and the back face deformation and delamination are significant (karmakar, 2022). several investigations (koene et al., 2013; koene & broekhuis, 2017, 2019) have argued about the penetration into wood-based materials and wood. authors developed non-load-bearing panels for the walls of the buildings, made using prefabricated press-formed uhmwpe in varying configurations with birch plywood. its thickness and brand were chosen because it is relatively commonly used but at the same time thick enough and of high strength/hardness to predict the retention of a 9 mm caliber bullet. also (sanborn, 2018) selected 1 inch (2.54 cm) thick uhmwpe in the experiments. as well as they could act as a “net” within the composite, deforming and perforating and providing significant energy loss to the projectile by dissipating its energy over a larger area and thus reducing its ability to penetrate (sanborn, 2018) uhmwpe combined with clt material lacks the overall strength and stiffness for use as a structural panel. the negative aspect is that uhmwpe material is expensive compared to other bulletproof materials such as fiberglass, metal plates, etc. (sanborn, 2018) the numerical outcomes reveal the hybridization and distinctive stacking sequence of hybrid composites show a critical response to the ballistic performance. the outcomes additionally show that energy absorption capacity and ballistic limit velocity are delicate to projectile nose shape. (karthick & ramajeyathilagam, 2022). the aim of this work is to verify whether the polyethylene-plywood panels withstand ballistic loads using 9 mm caliber glock 17 luger bullets. both material coefficients of thermal expansion are not close – for uhmwpe, it is α=2·10-6 k (rama sreekanth & kanagaraj, 2014), but for plywood (temperature 20 °c and 65% relative humidity) α=28–31·10-6 k. methods the authors designed non-load-bearing walls of the buildings, made using uhmwpe in different configurations of press-formed panels with birch plywood. the experiment occurred under controlled conditions at the riga shooting range. the air temperature during the experiment ranged from +5.1…+7.0 °c (january), and the relative humidity ranged from 65…70% (measured over 2 hours). a semi-professional shooter fired the bullets, thus bringing the situation closer to reality. due to the limited test conditions, en1522/23 requirements were not completed, such as: _ a count of specimens – a minimum of 3 specimens are required for each design variant. _ the foil shot indication plate was not used. _ the room temperature must be not less than 12.7 °c to qualify for the official ballistic rating of the polyethylene-plywood panels designed. the material damage results are described in the research work based on photographic recordings during the experiments. possible material damage and ballistic resistance of the panel, depending on the material of the panel façade, were considered. sample panels were prepared from uhmwpe 150 mm wide and 20 mm thick and laminated plywood 32 mm (1 mm of each side is the lamination) thick with dimensions 500x500 mm. they were mechanically fastened using spec 17 galvanized yellow screws ø 6 mm to a specially prepared wooden support (1000 mm high, 1500 mm wide) to test the material sample resistance to a fire 9 mm lead bullet. (table 1) plywood samples were made from lf-cpr/ce-dop-01 – riga® birch plywood (as latvijas finieris) with a laminated surface coating, glued with phenolic formaldehyde glue, ext glue quality, service class 2. harmonized technical specification with en 13986+a1:2015. the research limit was to use uhmwpe material in only one layer because the uhmwpe material is not the most cost-effective (table 1). the future projections are to use recycled uhmwpe material, thus reducing panel costs and increasing sustainability. journal of sustainable architecture and civil engineering 2023/1/32 236 by en1522/23 and en1063, a 9 mm luger cartridge for all tests was used. the experimental bullet was a standard 9 mm full metal copper jacket with 9 mm, 9x19 mm “parabellum-luger” ammunition with a weight of 8 grams. this cartridge type is used in tests where the structure or material to be tested (certified) has a declared ballistic resistance of fb2/br2. the designed plate shall have the characteristic of preventing projectiles from penetrating at least 9 mm caliber cartridges. the glock 17 pistol was used in the experiment. it belongs to the austrian company glock gmbh glock series pistols. the glock 17 pistol is chambered for 9 mm luger cartridges. the specimen is mounted on a frame to reduce relaxation on impact, avoiding any indirect absorption of the energy generated by the shot by the mechanisms. the samples were tested without back support (carrillo et al., 2011a). according to standard en 1063, there are expected to have three shots for each specimen. thus similarly, in this experiment, 2-4 attempts were made. the number of shots to each sample was chosen based on the expectations of the highest resistance as no. 1_2 was the flattest and most economical material; thus 4 shots were fired. that was the only exception, as 2 shots were taken on the other specimen. the specimens were tested at the impact velocity of 330 m/s, a 10-meter distance to the target, with a steel projectile considered to be non-deformable, with a diameter of 9 mm and a mass of 8 grams. based on the calculations made with these data, the impact energy or energy used to assess the damage caused by the projectile was calculated. this energy was calculated using equation (eq.1) w!"# = $ ∙'! ( = ),))+ ∙,,) ! ( = 435.6 j (1) e, j – is the kinetic energy of the projectile, m, kg – the mass, and v, ms-1 – the velocity of the shot. the energy is obtained using these values as the projectile’s energy that hits the sample. when the projectile manages to pass through the objective and residual velocity/energy is zero, as there is no perforation. (carlucci & jacobson, 2018; carrillo et al., 2011b; sanborn, 2018). material thickness (mm) density (kgm-3) weight (kgm-2) price (€m-2) uhmw pe1000 (white) 20 930 23.25 310.29 uhmw pe1000 (green) 25 930 18.60 256.29 plywood 32 mm 32 670 21.44 26.06 plywood 2x32 mm 64 670 42.88 52.12 table 1 the econometric indicators of the materials used (prices august 02, 2022) experimental part this research is limited to the following: _ glock 17 arm weapon with a bullet velocity of 400 m/s. _ bullet’s ogive-shaped nose. _ random angle focusing on the perfect outcome, like a 90° angle between the bullet and a surface. _ the shooting range temperature is +6–7 °c in january. _ two materials were used– plywood and uhmwpe. first, the experiment tested individual uhmwpe panels and laminated plywood material to monitor the ballistic damage. four different material samples were tested in the first part: 237 journal of sustainable architecture and civil engineering 2023/1/32 fig. 1 sample no.1, 32 mm thick birch plywood “riga” front face after firing _ material sample no.1 is a 32 mm thick birch plywood board “riga” with surface coating. _ material sample no. 2 is a 32 mm thick birch plywood board “riga” with surface coating – 2 layers, mechanically joined with four spec 17 metal screws ø6 mm. total thickness 64 mm. _ material sample no. 3: uhmw pe1000, white – thickness 20 mm. _ material sample no. 4: uhmw pe1000, green – thickness 25 mm. second, the experiments were about uhmwpe in different configurations with plywood. plywood and polyethylene boards separately. the samples were tested with a glock 17 pistol and a 9 mm luger cartridge. shots were fired from a 10 m distance. the air temperature at the shooting range at the time was +7 °c, with a relative humidity of 65 %. first, sample no 1 (see fig. 1 and fig. 2) was tested. the plywood material did not stop the bullet as it was predicted. fig. 2 sample no.1, 32 mm thick birch plywood “riga” back face after firing fig. 3 sample no.2 birch plywood “riga” 2x32mm front face after firing fig. 4 sample no.2 birch plywood “riga” 2x32mm back face after firing fig. 5 sample no.3 uhmw pe1000, 150 mm wide board, thickness 20 mm, white fig. 6 sample no.4 uhmw pe1000, 150 mm wide board, thickness 25 mm, green 1 2 sample no.2: 32 mm thick birch plywood “riga” (with surface coating) 2 layers, mechanically joined with four screws. total thickness 64 mm. see fig. 3 and fig. 4. two shots were fired with a glock 17 pistol. also, double plywood did not stop the bullets. 3 4 the third and fourth materials uhmwpe sheets 150 mm wide, 20 mm, and 25 mm thick, uhmw pe1000 white and green color, respectively were tested next. shots were fired from 10 m. the air temperature at the shooting range at the time was +7 °c, with a relative humidity of 70 %. shots were fired with a glock 17 pistol, using 9x19 mm luger cartridges. uhmwpe stopped no bullets in samples 3 and 4. see fig. 5 and fig. 6. 5 6 journal of sustainable architecture and civil engineering 2023/1/32 238 table 2 bullet resistance of polyethylene – plywood panels panel no. panel position projectile penetrated the material bullet stopped in experimental penetration depth, mm 1_1 front 20 mm uhmwpe 9mm luger yes >53 back 32 mm plywood 1_2 front 32 mm plywood no uhmwpe 53 ± 1 back 20 mm uhmwpe 2_1 front 20 mm uhmwpe no plywood, 2nd board 61 ± 1 back 2x32 mm plywood 2_2 front 2x32 mm plywood no uhmwpe 74 ± 1 back 20 mm uhmwpe fig. 7 plate 1_1.uhmwpe 20 mm – plywood 32 mm front face fig. 8 plate 1_1. uhmwpe 20 mm – plywood 32 mm side face plywood-polyethylene boards. materials separately did not stop the bullet; thus, the second part of the experiment was to verify if the combination of the prior two materials was successful. therefore, the authors designed load-bearing and non-load-bearing panels for the walls of the buildings, made using uhmwpe in different configurations of press-formed panels with birch plywood. the combinations are also seen in table 2. panel no. 1_1. uhmwpe 20 mm – plywood 32 mm did not stop the bullet from glock 17 pistol. the polyethylene layer was shot through, and the bullet penetrated the plywood. the plywood has delaminated 11 cross-laminated birch plywood sheets (1.45 mm thick each) in the adhesive layer (fig. 7, fig. 8), which have damage in the third wood veneer layer (not in the adhesive layer). the material did not stop all two control bullets. 7 8 panel no. 1_2. sample 1_2 consists of 32 mm plywood followed by uhmwpe 20 mm as the second layer. the handgun fired four shots. the plate stopped the bullet on the first shot (fig. 9). the bullets penetrated plywood, but the uhmwpe stopped the bullet. local deformations in the polyethylene were found, coinciding with the bullet’s trajectory. after the sample panel was extruded (fig. 10), a deposit at the extrusion mid-point was found, presumably due to rapid internal temfig. 9 plate 1_2. plywood – uhmwpe fig. 10 plate 1_2. plywood 32 mm – uhmwpe 20 mm after firing 9 10 239 journal of sustainable architecture and civil engineering 2023/1/32 perature fluctuations. since uhmwpe material has a melting point of 130 °c, a short-term impact at this temperature will not cause permanent deformation. the shooter performed three more control shots. all bullets were intercepted, including no.2 and no.3, fired closely and stuck in the same channel. no deformation increase in the polyethylene facade was detected when bullet no.3 struck bullet no.2. possibly, the energy of the fired bullet was partially transferred to the existing channel of bullet no.2. the temperature rose; however, the energy was not sufficient for the proceeding of deformation. the maximum experimental penetration depth was measured as 53 mm. sample 2_1 consists of uhmwpe 1000 – 1 layer and 32 mm thick birch plywood “riga” (with surface coating) double. total thickness 84 mm. (20 mm + 2x32 mm) (fig. 11). the bullet embedded into the second plywood board. the experimental penetration depth was measured as 61 mm. it was seen that the bullet penetrated the polyethylene and plywood’s first layer but was stuck in the second plywood layer. the ballistic experiment revealed that the arrangement of the polyethylene layer influences the ballistic response. sample 2_2 consists of 32 mm thick birch plywood “riga” with two layers of surface coating and 20 mm uhmwpe. total thickness 84 mm (2 x 32 mm + 20 mm) (fig. 12) the plate retained the bullet. the bullet was shot through 2 layers of plywood and stopped in the polythene. the experimental penetration depth was measured as 74 mm. we detected no local deformation of the facade in the polyethylene. fig. 11 plate 2_1. uhmwpe 20 mm – plywood 32 mm fig. 12 plate 2_2. plywood 2x32 mm – uhmwpe 20 mm11 12 in the first part of the experiments, no sample of the plate material (without combining them) stopped the fired cartridge bullets. the observations showed that uhmwpe panels and plywood at 20 mm and 25 mm thickness alone are unsuitable for practical use in protection against small and standard caliber projectiles. discussion fig. 13 the experimental penetration depth (mm) of the bullet for each plate combination fig. 13 shows that the uhmwpe board in the front and the plywood board in the second layer (1_1) do not stop the bullet. but if there are two plywood boards (2_1), the bullet stops in the second plywood board, making a 61 mm penetration depth (marked). the 1_2 variation of 32 mm plywood first and uhmwpe 20 cm second journal of sustainable architecture and civil engineering 2023/1/32 240 fig. 14 measurements of penetration depths made 61 mm terminal in a sample. but with 2x32 mm plywood, it is a 74 mm terminal. as this researched wall is a retrofitting wall, the thinnest wall is 52 mm of these boards to protect residents of the building. the experimental penetration depth was measured manually using a steel bar with a diameter of 3 mm and a ruler with an accuracy of 1mm. (fig. 14). to compare the results with sanborn, where the uhmwpe panel was mechanically affixed to the two clt sections due to concerns with bonding the materials. this uhmwpe panel was one inch thick (25.4 mm) and placed between the 2-ply and 3-ply sections of clt. specimens with fiber-based ballistic panels also increased the ballistic resistance of the panel and were significantly lighter than the product with metal plates. (sanborn et al., 2018) fiber-based ballistic panels are expensive despite their excellent performance (carrillo et al., 2011b). the aim of this work is completed – the polyethylene-plywood panels in the right order withstand frontal impacts of high-speed projectiles using 9 mm caliber glock 17 luger bullets. the best sequence for the bullet resistance was 1x32mm plywood and uhmwpe as an inner layer. bullets were embedded in polyethylene. uhmwpe’s hardness combined with plywood is bullet impact resistant for the bullet’s initial speed of up to 400 m/s. these boards can be bullet-proof walls (at least non-bearing). the uhmw polyethylene begins to melt after receiving the initial load from the bullet. melting means the kinetic energy is sufficient to heat the polyethylene to 130 °c. plate 1_2 consists of two 32 mm thick plywood layers outside mechanically bonded to a 20 mm thick uhmw polyethylene plate inside, which can qualify for ballistic resistance class fb2/br2 to en1063 and en10522/10523. birch plywood 32 mm thick absorbs the kinetic energy of a bullet to such an amount that the residual energy is insufficient to penetrate a 20 mm thick uhmw polyethylene sheet. after the shot, it is possible to visually restore the panel with different options, like increased temperature by fusing the uhmwpe material). still, it is unlikely that this repaired area would have the same level of protection against the next potential bullet. alternatively, the hole/channels can be recessed/replaced with a stronger material (e.g., metal rod). this can be done immediately, so there are no open channels for an imminent attack (shot). the next experiment would be varying the thicknesses of the plywood and uhmwpe boards (notably, the thickness of plywood could likely be reduced in tests 2_1 and 2_2) to make sure the min(a) (b) (c) 241 journal of sustainable architecture and civil engineering 2023/1/32 imal possible thickness is used for the maximum lightness of the wall, as well as in combination with other ballistic materials, like aramid fiberboard (borodinecs et al., 2022). computer simulation would be considered for further study. these loads are not static and dynamic but high-velocity impact loads that make the simulation labor-intensive. conclusion ultra-high-molecular-weight polyethylene (uhmwpe) has many advantages, including ballistic protection, especially when combined with known materials such as laminated plywood. in panels designed from several materials with different physical properties, each material’s position (order) in the panel structure is essential. the material order can have a significant effect on the ability of the panel to resist ballistic loads. various laminated plywood and uhmwpe specimens were tested for ballistic resistance. separately they did not receive the ballistic limit, in contrast, specimen layers: plywood outside (at least 32 mm) – uhmwpe inside (20 mm) obtained relevant results than opposite order. thus, it can achieve the qualification for ballistic resistance class fb2/br2 to en1063 and en10522/10523. these panels can be a part of walls of various shelters like unclassified buildings, such as army headquarters, and safe rooms because of their relatively light density. the polyethylene-plywood plates could be used in structures in the arctic regions where temperatures are permanently low (down to -70°c). because of the radio-impermeability property of polyethylene, the boards could be used both for the construction of residential arctic complexes (screw piles, for instance) and for scientific structures, protecting with boards the radio-communication equipment that is essential for the development of the arctic region and military applications as well. the arctic region is considered the most promising region in terms of natural resources. as world history shows, most of the world’s major armed conflicts occur in natural resource-rich regions; the use of panels will be appropriate to the risks involved. acknowledgment this research was supported by riga technical university’s doctoral grant program. attwood, j. p., russell, b. p., wadley, h. n. g., & deshpande, v. s. 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(2018). ballistic performance of enhanced cross-laminated timber (eclt). wit transactions on the built environment, 180, 267-278. https://doi.org/10.2495/ susi180241 tulatorn, v., ouajai, s., yeetsorn, r., & chanunpanich, n. (2015). mechanical behavior investigation of uhmwpe composites for pile cushion applications. kmutnb international journal of applied science and technology, 1-12. https://doi.org/10.14416/j. ijast.2015.08.001 ur rehman, z., niaz, a. k., song, j. il, & heun koo, b. (2021). excellent fire-retardant properties of cnf/ vmt based lbl coatings deposited on polypropylene and wood-ply. polymers, 13(2), 1-13. https://doi. org/10.3390/polym13020303 van dingenen, j. (1989). high performance dyneema fibres in composites. materials & design, 10(2), 101-104. https://doi.org/10.1016/s02613069(89)80021-4 wood w. (2012). processing, wear, and mechanical properties of polyethylene composites prepared with pristine and organosilane-treated carbon nanofibers. materials science. https:// w w w . s e m a n t i c s c h o l a r. o rg / p a p e r / p r o c e s s ing%2c-wear%2c-and-mechanical-properties-of-with-wood/696d10cd6ceb864433bf3ca43886e7d803b8f3c0 wu, x., tang, b., & li, h. (2021). research on the effect of uhmwpe cavity protection board on rapid enhancement of wall anti-blast performance. iop conference series: earth and environmental science, 647(1), 012084. https://doi.org/10.1088/17551315/647/1/012084 243 journal of sustainable architecture and civil engineering 2023/1/32 about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). elina barone researcher, ph.d. student riga technical university, faculty of civil engineering, department of building technology main research area bullet-proof wood-based buildings, wood materials address kipsalas street 6a-348, lv-1048, riga, latvia tel. +371 29810867 e-mail: elina.barone@rtu.lv edvins velicko master student riga technical university, faculty of civil engineering, department of building technology main research area wood-based buildings, polyethylene, shooting address kipsalas street 6a, lv-1048, riga, latvia tel. +371 29439998 e-mail: edvins.velicko@edu.rtu.lv baiba gaujena associate professor riga technical university, faculty of civil engineering, department of building technology main research area sustainable construction, eco-materials, energy efficiency, building structures address kipsalas street 6a, lv-1048, riga, latvia tel. +371 26327631 e-mail: baiba.gaujena@rtu.lv martins vilnitis professor, dean of faculty of civil engineering riga technical university, faculty of civil engineering main research area sustainable construction address kipsalas street 6a-343, lv-1048, riga, latvia tel. +371 29439998 e-mail: martins.vilnitis@rtu.lv 27 the impact of the specific elements of globalization on the spatial structure of lithuanian towns and their valuation giedrė gudzinevičiūtė-vilkelė*, evaldas ramanauskas kaunas university of technology, institute of architecture and construction,tunelio st. 60, lt-44405 kaunas, lithuania. *corresponding author: giedre.gudzineviciute@ktu.lt http://dx.doi.org/10.5755/j01.sace.4.5.4836 processes and occurrences in the world are becoming more and more globalized and that is reflected in lithuanian towns as well. depending on scale of globalization, towns take new expression with unified symbols, the uniform elements of urban space, separate objects, networks, etc. these objects mainly are dedicated to develop the spheres of services and commerce. very often these objects and their networks do not take into account place and do not reflect its singularity, but only form and expand unified symbols of their own. in such way urban localities, where these objects are developed, are decreased and belittled. unified view usually does not take into account exceptional current urban, architectural, natural, landscape and identity conditions. paper analyses current situation of these globalization elements, their meaning to the landscape and spatial structure of lithuanian urban spaces. new constructions confirm characteristic feature for nowadays globalization: territories of historic urban structures and their synthesis change all the time. urban environments are shaped by maintaining specific existing identity roles and further developing the town that is formed by global processes that stimulate changes of its identity. size of new constructions and quality of architectural-urban solutions that are based only on economic aims, show the weakness of urban thought and understanding of globalization, weak abilities to request possibilities that are given by globalization to cherish town identity but not to suppress it. under conditions of globalization it is important that towns could save the most important – national and regional identities. after that they should save local identity, natural surroundings, town silhouette, form, and architectural character. analyzing lithuanian towns and clear reflections of globalization in their spatial structure, there could be consumption culture excluded as separate expression that alters the identity of cities and towns with global elements. during lithuanian cities and towns identity research it was established that the identity and local architecture were saved mainly by creating small shops that do not require huge spaces and there are possibilities to organize them in existing reconstructed buildings. such types of “shops near home” quite often are organized in existing buildings, and from outside they might be recognizable by names or logos. huge shopping centers are usually organized in new big buildings, where besides shopping people can find other services or entertainments. these buildings usually are standardized, very similar in their form and architecture, minimally adapted to urban surrounding, they do not reflect, continue and form local architecture traditions, townscape, aesthetic view, but destroy it. keywords: aesthetics, architecture, identity, globalization, town. 1. introduction nowadays many processes around us are understood and valuated through the prism of globalization. currently ongoing urbanization and urban sprawl are valued as specific expression of globalization that is induced by human life changes, development of technologies, etc. together with globally activated social, economic, cultural factors, form and inside of towns changes as well. new requirements of town development and formation appear. because of globalization’s specific feature to standardize everything around, the threat to the identity of cities, towns and villages emerges. today this question is emphasized in by the relevant concept of sustainable development. it tries to solve the problems of urban sprawl, urbanization control, preservation of natural surrounding and others. globalization – process, occurring in social space, including different spheres of activities of society, country and other social organizations. it reveals itself by more intensive connections, mobility and other characteristics in the scale of the whole world. this concept means, that social, political and economic activity exceed country borders and events, decisions or activities in one region might be meaningful to the individuals or societies in the other region darnioji architektūra ir statyba 2013. no. 4(5) journal of sustainable architecture and civil engineering issn 2029–9990 28 of the world. from the architectural-urban point of view the globalization might be seen as building architecture and the uniformity of town spaces caused by it. as the phenomenon, globalization and its interaction with other processes and objects is analyzed by the specialists from many different fields: architectural, urban (dringelis et al. 2006), philosophical (bauman 2002; castells 2005), cultural (petrušonis 2005; butkus 2011; samalavičius 2002; held 2002), identity (rubavičius 2005), heritage protection (čepaitienė 2006) and else. the aim of the paper is to discuss specific elements of globalization and their impact on lithuanian cities and towns. the tasks of the paper are to distinguish especially influential, easily recognizable globalization related objects – elements of the urban spaces, to compare and evaluate them. in order to receive the results of the paper, specific object selection and comparative methodologies were used. the globalization elements analyzed in the paper are architectural objects or their parts that are used for commercial purposes. the paper also evaluates such aspects as developed of commercial networks, their structure and identity in small or large towns. 2. globalization influence to the identity of towns spatial structure globalization in lithuania appears in different ways. similarly as in all the world, people’s life, living surroundings and habits become more and more global by the wide use of modern technologies, traveling, keeping mobile and else. globalization in lithuania as in all the world touches various spheres of human life – from wide social, to very narrow personal, political, worldview and else. of course, much stronger globalization affects larger urban places – naturally here intersect more global connections and nets with objects existing there. the bigger town is, the bigger global pressure it feels. but together with that it gets more global possibilities too. accordingly the residents of cities and towns – in more global surroundings they live, the more possibilities they have getting global and creating new global surroundings. one of the main globalization problems in towns and people’s life appears when there is an urge to save the local identity. for the person to save personal identity is much easier, in spite of that he is affected by global factors. it is his own choice to take part in many processes and to became global. in urban places regulation of globalization is much harder, because of functioning of separate people, their groups, local and foreign companies that create different products, give services and develop their networks. according to m. castells (2005), „new global economics and forming information society gain new – megacity – spatial form that becomes apparent in various social and geographical contexts.“ this megacity may be understood also in the figurative way that it is not only very large city or town – it might be really small town that belongs to the global net. analyzing globalization and identity in the urban space, it can be identified (morkūnienė 2003) that under conditions of globalization, tension appears in urban culture between such objects: ▪ between global and local. that problem is expressed by question how different, small country might slowly join to the society of the world by saving its roots and cultural identity that in a big part is reflected in the cities and towns; ▪ between traditions and modernism. this problem appears by willingness to save variety of cultures under conditions of globalization. willingness to improve, to live modern life is related with the wish to save distinctive, characteristic urban spaces, forms and else; ▪ between long-term and short-term aims. now usually instant aims dominate and problems are solved hastily. on the other hand, a lot of problems require strategies and discussed actions. identity of the town is shaped when urban structures interact with natural surroundings. even if identity and its continuity before some time were not held as significant urban or socio-cultural valuable thing, now they became very important. identity and distinction problem was raised by town’s significance in the process of globalization. so the most important becomes question if town is able to keep all its identities among economic, cultural, technologic globalization or it becomes just a place where global processes happen. new constructions confirm characteristic feature for nowadays globalization – territories of historic urban structures and their synthesis change all the time. urban environments are shaped by maintaining specific existing identity roles and further developing the town that is formed by global processes that stimulate changes of its identity. size of new constructions and quality of architecturalurban solutions that are based only on economic aims, show the weakness of urban thought and understanding of globalization, weak abilities to request possibilities that are given by globalization to cherish town identity but not to suppress it. “concrete physical elements of urban development may expose or may equalize visual expression of the landscape, together identity and uniqueness of landscape characteristics.” (laukaitytė-malžinskienė 2008). so it is commendable conception of landscape or town character – it is unique and recognizable totality of elements that is not making the locality better or worst, but make it exceptional and unrepeatable from other localities. urban development through concrete physical elements also may expose or may equalize expression of town and its wholeness identity and uniqueness. one more specific town and culture identity field is cultural heritage. „it is more than buildings, it covers identity of all town, town is analyzed as totality of different qualitative layers“ (petrušonis 2005). such treatment reflect the fact that town may be interpreted in different ways. on the other hand, problems of identity can’t be linked only with history – they have to be analyzed in the context of nowadays problems. in order to achieve the 29 sustainable development, it must be taken into account that the information about the identity of the locality has to be flexible for its more dynamic use in the changing current world. according to v. petrušonis (2005), “codes of identity models must be such that they would not contradict to historical context and while in the mind of the planner spontaneous changes are going, it would ensure frankness to the modern context.” so, identity must be created such that it would reflect historic development, but at the same time it must be adapted to nowadays surroundings and their changes. under conditions of globalization it is important that towns could save the most important – national and regional identities. after that they should save local identity, natural surroundings, town silhouette, form and architectural character. 3. insight on the elements of globalization in the towns of lithuania analyzing lithuanian towns and clear reflections of globalization in their spatial structure, the consumption culture could be excluded as separate expression that alters the identity of cities and towns with global elements. in the article the consumption culture as the reflection of globalization is analyzed in 4 different situations according to the expression and functioning principles: 1. standardization. all of us are able to observe and aesthetically evaluate unified, typical architecture of commercial and service networks in many lithuanian cities and towns where these networks develop their activity. 2. recognizable elements. probably it would be hard to find commercial business network that would not seek to distinguish oneself from others. by creating easily recognizable symbols, names and other elements that usually are used even creating their architecture, these networks try to occupy niche in the business world and make its activity more popular. 3. subsidiary means in architecture, design and visual expressions – commercials, advertisements and their stands in the spaces of towns, on the facades of the buildings and else. the aim of these commercials is to stimulate the usage and to affect the behavior of people, to socially orientate them. 4. in these standardized, easily recognizable, advertised objects and oldest globalization activity – trade, huge masses of people are involved. standard architecture and commercials stimulate people to join these global networks and indirectly support their further development by visiting them. so it is indirectly confirmed that developed trade and offered activities are acceptable and valuable. during the research of identity of lithuanian cities and towns it was established, that the identity and local architecture was in the most cases saved by creating small shops that do not require huge spaces and there are possibilities to organize them in currently existing reconstructed buildings. such types of “shops near home” quite often are organized in existing buildings and from outside might be recognizable by the names or logos. huge shopping centers are usually organized in new large buildings where besides shopping people can find other services or entertainments. abroad these centers mostly are visited once a week. these buildings usually are standardized, very similar in their form and architecture, minimally adapted to urban surrounding, they do not reflect, continue and form local architecture traditions, townscape, aesthetic view, but destroy it. glancing at these buildings the question may arise how these buildings may be valuable and how people may relate them with one but not other lithuanian city or town. their expression is anonymous – they are not connected with locality, do not preserve its current and make recognizable only the network which they represent. here may stand the question: if such building would be taken away from the territory of the town – would local people miss it? would they miss it like they would miss the church or other close and dear object taken away? on the other hand creation of commercial networks as the process of globalization is not new. once the religious globalization was intensively going on and the network of churches in the urban places was created too. the only difference, that every church was built different. function is the same, size, form, surface materials – different. adapted to local landscape and architectural traditions they continued traditions of locality identity. according to v. rubavičius (2005), very important aspect must be underlined – “town identity exist only if local people support it by their way of life. according to that, it is important not only memory, but also variety of town life and historical its continuity.” so it is very important to know the history of town, its development evolution, know and recognize the distinguishing features and plan town identity continuity by supporting them. the contemporary shopping centers and some catering services networks might be compared with the soviet era multi-flat standardized housing that was built not even in one country, but in the whole soviet region. from the time perspective it is possible to evaluate objectively if these buildings became a very valuable architecture, if even a small part of them is considered built heritage, etc. the standardized architecture of the soviet time construction and the contemporary shopping centers demonstrates that functionality here is considered more important than all other architectural and urban characteristics. now function goes in front of the form and this in some way ensure further development of such “architecture”. such standardization is easily defined in the architecture of commercial buildings. of course, some standardization appears in cultural, sport and other buildings too, but not on that scale as on commercial buildings. this shows, that now, during globalization time, money is able to do all and to go through all. unique, exceptional, with local characteristics architecture of lithuanian cities and towns is important part of our culture. with discussed commercial buildings and 30 their architectural expression, the foreign culture is repeated and conveys the lost traditions. all this is based on the shortterm economic aims. similar threats, like danger to lose local identity are accepted not only locally, but internationally too. analyzing the concept of culture l. donskis (1993) emphasized such borders of the cultural function of the town: “speech of cultural forms is understandable only by humans; culture as huge text can be red also only by humans. if culture is authentically and adequately “read”, in real life it becomes the thing, without which humanity can not exist – collective experience and its models, collective memory and its forms.” lithuania, being in cultural joint and cherishing its own cultural traditions from the past, distinguishes itself with valuable and significant historical and cultural heritage, original interaction of different cultural traditions and free expression that has to be preserved and continued even in the global world. 4. valuation of the elements of globalization in the urban places of lithuania how these objects affect urban places of lithuania and their identity, what information they provide? large shopping centers and services networks fist of all locate their nodes in the biggest urban places, later thicken the network in the smaller urban places and so on. along urban place size and probable flows of visitors, the node often gets bigger or smaller “package” of goods or services, trade area, number of boutiques or services. since most of such shopping and service nodes are divided to the different levels, so mentioned aspects becomes typical and unified for each level. this of course reflects on the surface of buildings – in its size, facades, materials. in such way object becomes easily recognizable in any place and gives a signal to the people with primary information – what, how many, what level you may expect and get. in such way expectations become very similar and they are fulfilled similarly, because one network offers its standardized services and quality. discussed commercial buildings, as usual elements of globalization can be found in almost all urban places of lithuania. depending on the people flows – potential customers, different size shops are built, but their architecture and expression is uniform (fig. 1– 3). fig 1. shopping center maxima in lazdijai (shopping… 2013a) fig 2. shopping center rimi in alytus (shopping… 2013) fig 3. shopping center rimi in marijampolė (shopping... 2013c) such anonymous architecture, that does not create new aesthetical quality, looks alike to logistics, warehouse, vehicle service buildings (fig. 4, fig. 5). fig 4. logistic center in vilnius (logistic… 2013) fig 5. vehicle service center in vilnius (vehicle… 2013) 31 nowadays the architecture of the shopping centers encumbers urban spaces, obstructs and covers significant objects – cultural heritage objects, monuments, even urban structure of historic urban center or other urban area (fig. 6, fig. 7). fig 6. shopping center akropolis in kaunas (shopping… 2009) fig 7. shopping center maxima in marijampolė. behind shopping center – st. archangel mykolas basilica (shopping… 2013b) developing aesthetically valuable architecture and environment in lithuanian cities and towns, also admitting the processes of globalization, it is possible to create new values by using existing buildings and urban spaces. in such way the continuous identity and distinctiveness of urban space would be saved, local globalization would be ensured. logos taken from the existing, architecturally, culturally and aesthetically valuable building might be easy changed by other ones (fig. 8–10). fig 8. shop maxima in existing building in šilutė. (shop… 2013) fig 9. shop maxima in existing building in vilnius (foto andriaus ufarto/bfl) (shop… 2013a) fig 10. shop maxima in the multi flat house in vilnius, a. smetonos st. (shop… 2013b) in such a way the further existence of the valuable buildings is ensured on the other hand, would towns have the same valuable buildings left if the symbols and names from the contemporary shopping centers would be taken away? only anonymous boxes without any architecture that do not enrich our town’s spatial structures, but only depreciate it, would remain. 5. conclusions 1. influence of globalization is felt in the entire world, in lithuania as well. this process is almost not controlled, because there are no physical borders between countries, possibilities to travel daily become better, information technologies have improved. there is only chance to choose the way how to globalize – unconditionally accepting new processes or regulating them according to local traditions. 2. consumption culture as one of clearly visible and understood reflections of globalization might be divided to 4 groups that all together or separately form and change identity of lithuanian urban places. that is standardization, usage stimulation, recognizable elements, commercials and advertisements, other processes that are orientated to conscious stimulation of using. 3. shopping networks usually are developed by building new typical buildings that do not create new architectural value, but depreciate spatial structure of urban 32 places. because of their influence lithuanian cities and towns get uniformed, that weakens their local identity. 4. if globalization aspects will rise, than new, not valuable architecture may weaken or destroy local identity of urban spaces. this is the base for higher requirements for new shopping networks buildings, also base for requirements of local urban history and its specifics respect. 5. in order to preserve the local identity of the spaces of cities and towns, it is necessary to review planning rules and design requirements of commercial and services networks buildings. acknowledgment the research represented in this article was financed by research council of lithuania. agreement no. vat60/2012. straipsnis parengtas pagal lietuvos mokslo tarybos finansuojamo projekto tyrimų medžiagą. sutarties nr. vat60/2012. references bauman z. 2002. globalizacija: pasekmės žmogui. vilnius, strofa. butkus t. s. 2011. miestas kaip įvykis: urbanistinė kultūrinių funkcijų studija. kaunas, kitos knygos. castells m. 2005. informacijos amžius: ekonomika, visuomenė ir kultūra. t. 1. tinklaveikos visuomenės raida. kaunas, piligrafija ir informatika. čepaitienė r. 2006. kultūros paveldas ir lietuviškasis tapatumas. in: kultūros paveldas ir visuomenė xxi a., nacionaliniai ir tarptautiniai aspektai. vilnius, 111–118. donskis l. 1993. moderniosios kultūros filosofijos metmenys. vilnius, mokslo ir enciklopedijų leidykla. morkūnienė j. 2003. globalizacija: taikos kultūra, žinių visuomenė, tolerancija. kaunas, aušra. held d. ir kt. 2002. globaliniai pokyčiai: politika, ekonomika ir kultūra. vilnius, margi raštai. laukaitytė-malžinskienė g. i. 2008. kraštovaizdžio vizualinės raiškos savitumo apsauga didmiesčio priemiestinėse teritorijose. urbanistika ir architektūra, 2(32), 103–112. dringelis l. ir kt. 2006. lietuvos regionų gyvenamųjų vietovių urbanistinės plėtros tyrimai. ataskaita. kaunas, kauno technologijos universitetas. logistic center in vilnius. 2013. available at: http://www. statybuprieziura.lt/projektai/igyvendinti/logistikos-centras (accessed 27 june 2013). petrušonis v. 2005. vietovės kultūrinio tapatumo ontologija. urbanistika ir architektūra, 2(29), 55–62. rubavičius v. 2005. miesto tapatumas ir išskirtinumas globalizacijos sąlygomis. urbanistika ir architektūra, 4(29), 157–163. samalavičius a. 2002. nuo masinės kultūros kritikos iki kultūros globalizacijos. kultūros barai, 4(449), 2–5. shop maxima in existing building in šilutė. 2013. available at: http://www.miestai.net/forumas/showthread.php?t=3960 (accessed 27 june 2013). shop maxima in existing building in vilnius (foto andriaus ufarto/bfl). 2013a. available at: at: http://www.balsas.lt/ naujiena/245085/maxima-uzdaro-septynias-parduotuves (accessed 27 june 2013). shop maxima in the multi flat house in vilnius, a. smetonos st. 2013b. available at: http://www.dizaja.lt/index.php?nr=25 (accessed 27.06.2013). shopping center akropolis in kaunas. 2009. available at: kaunas: verčiame naują puslapį. kauno miesto savivaldybės 20072008 veiklos ataskaita (accessed 27 june 2013). shopping center rimi in alytus. 2013. available at: http://www. alytausgidas.lt/lt/fotogalerija/alytus-nuo-1990-m/prekyboscentras-rimi-2008-m (accessed 27 june 2013). shopping center maxima in lazdijai. 2013a. available at: http://dzukuzinios.lt/lazdijuose-atidaryta-antra-maximaparduotuve (accessed 27 june 2013). shopping center maxima in marijampolė. behind shopping center – st. archangel mykolas basilica. 2013b. available at: google street view http://maps.google.com/map (accessed 27 june 2013). shopping center rimi in marijampolė. 2013c. available at: http:// klaipeda.diena.lt/naujienos/ekonomika/-rimi-atidaro-naujaparduotuve-marijampoleje-283102 (accessed 27 june 2013). vehicle service center in vilnius. 2013. available at: http:// augejas.lt/objektai/autoservisas-wirtgen-vilnius (accessed 27.06.2013). received 2013 07 24 accepted after revision 2013 10 10 giedrė gudzinevičiūtė-vilkelė – junior researcher at kaunas university of technology, institute of architecture and construction. main research area: territory planning, urbanism, globalization. address: tunelio st. 60, lt-44405, kaunas lithuania. tel.: +370 37 451372 e-mail: giedre.gudzineviciute@ktu.lt evaldas ramanauskas – project researcher at kaunas university of technology, institute of architecture and construction. main research area: territory planning, land property, public interest. address: tunelio st. 60, lt-44405, kaunas lithuania. tel.: +370 37 451372 e-mail: evaldas.ramanauskas@ktu.lt 40 effects of interaction of static load and frost on damage mechanism of concrete elements marta kosior-kazberuk1* 1bialystok technical university, faculty of civil engineering and environmental engineering, wiejska 45e, 15-351 bialystok, poland * corresponding author: m.kosior@pb.edu.pl frost damage is typical material deterioration in concrete structures subjected to external environmental conditions. however, the weather conditions do not make the sufficient factor causing the worsening of the concrete properties. concrete structures with frost damage in service are subjected to loadings. the investigation was carried out with the primary objective to assess the influence of interaction of mechanical load and freeze-thaw cycles on damage process of concrete. the salt scaling process was observed for beam specimens subjected to cyclic freezing and thawing in third-point loading condition. the damage development due to internal cracking was monitored using fracture mechanics parameters. keywords: concrete, cyclic freezing and thawing, scaling, bending, fracture mechanics, interaction. darnioji architektūra ir statyba 2012. no. 1(1) journal of sustainable architecture and civil engineering issn 2029–9990 1. introduction under severe freezing climate conditions, frost action is probably the most important cause of deterioration of exposed concrete structures. even in structures with airentrained concrete, frost damage can occur under certain circumstances. usually, the weather conditions do not make the sufficient factor causing the worsening of the concrete properties. damage evolution as well as the concrete resistance to freezing and thawing have been of great concern of researchers for many years (pigeon et al. 1996, jana 2004, pentala 2006, valenza and scherer 2007). two types of damage to concrete may occur as a result of cyclic freezing and thawing: ▪ surface scaling, ▪ internal cracking. surface scaling is generally found where the surface of concrete is subjected to weak solutions of salt, typically used for de-icing purposes. internal freeze-thaw damage results from expansive stresses generated by water on freezing when the pore structure of the concrete is saturated above a critical value, and leads to internal microcracking. internal damage, which is likely to occur in concrete subjected to long-term wet/saturated conditions (fagerlund 2002), is manifested macroscopically by irreversible tensile deformation and randomly oriented microcracking (pigeon et al. 1996). hence, the freezing and thawing action can be looked upon as a very complex fatigue crack propagation process (hasan et al. 2008). the most of previous works on the freeze-thaw durability of concrete have been focused on the mechanical property degradation (e. g. modulus and strength), weight change, length change, microstructural change or ultrasonic signature change after different numbers of freeze-thaw cycles, sometimes in the presence of salt solution (cao and chung 2002). performance deterioration caused by a monodamaging process, such as freeze-thaw, is not consistent with real conditions to which concrete structures are actually exposed. it has been found that the deterioration of concrete could be accelerated when subjected to multidamaging processes, e. g. simultaneously exposed to external load, freeze-thaw cycles and chloride or sulphate attack. it is necessary to understand how the resulting stresses influence the concrete resistance to freezing and thawing. however, there are very few test results considering the effects of interaction of mechanical loading and cyclic freezing and thawing, and in large part, they concern the effect of internal damage on concrete properties (zhou et al. 1994, sun et al. 1999, yu et al. 2008). the analysis of research results, described in literature, has showed there is the lack of information concerning the influence of the tensile stress on the typical process of surface scaling due to freezing liquid contact with selected surface of element tested, which is the frequent situation in service life of concrete and reinforced concrete structures (şahmaran and li 2007). since salt scaling is superficial, it does not affect mechanical integrity of a concrete body. however, this damage renders material susceptible to ingress of moisture and aggressive species that threaten durability (valenza ii and scherer 2007). the concrete is a heterogeneous material of high compressive strength, but its resistance to cracking is http://dx.doi.org/10.5755/j01.sace.1.1.2616 41 low. the destruction of concrete under the influence of external loads is affected, among other things, by material discontinuities, disruptions, and local differences in mechanical properties of material. the local accumulations of stress caused by external pressures occur in the vicinity of concrete defects (gettu et al. 1990, jenq and shah 1991). they can cause violent propagation of damage, and finally lead to the destruction of the entire element. the most dangerous concentrators of stress are the tips of cracks where the greatest stress values are achieved (schlangen and garboczi 1997). in the progress of freezing and thawing, recurrent frost expanding and penetration compressive stress act on concrete, each cycle produce freeze-thaw inner stress in concrete interior, the stress causes inner flaws of concrete expand, accumulate and form new damage. freeze-thaw cycles and loads are both repetitive actions that cause accumulated physical damages in concrete. as the essential development and important supplement of fracture mechanics, damage mechanics is the part of material structure distortion and wreck theory, it emphasize the influence of material damage to mechanical properties, also the evolutive process and rules of materials or structure damage. fracture mechanics can help analyze the response of microstructure to external load (shah et al. 1995, bažant 2002, wang et al. 2010). so, it is reasonable and feasible to study the freeze-thaw damage rules of concrete by using fracture mechanics parameters. the critical stress intensity factor and the critical crack tip opening displacement, along with the young’s modulus, are sufficient to characterize the fracture resistance of concrete. the methods of fracture mechanics were approved in structural design by the latest proposal of ceb-fip model code (2010). two different approaches to the estimation of cyclic freezing and thawing influence on concrete properties were presented in the paper. the analysis of interaction of load and freeze-thaw cycles with chloride exposure regime on surface scaling process of concrete was performed. the fracture parameters were used to assess the internal cracking progress in concrete. the investigation was not intended to perfectly simulate loading and exposure conditions, but to begin to make the preliminary understanding about the complex deterioration mechanisms of concrete in real service life conditions. 2. methods specimen preparation the tests were carried on for non-air-entrained concrete as well as for air-entrained concrete. the cement (cem i 42,5) content in concretes tested was constant – 350 kg/m3, and water to cement ratio was equal to 0,40. the natural aggregate with maximum diameter of 8 mm was used. the air-entraining agent content was 0,10% related to cement mass. after demoulding the specimens were stored in water with temperature 20 ± 2 ° c. the compressive strength, tested after 28 days of curing, was equal respectively 59,7 mpa for non-air-entrained concrete and 55,2 mpa for concrete with aea. estimation of scaling resistance the specimens sizes were 80×120×1100 mm. every series was composed of 3 replicates. the concrete resistance to surface scaling due to cyclic freezing and thawing with de-icing salt saturation (3% nacl solution) was determined using the procedure described in pkn-cen tc 12390-9:2007. in order to realize the interaction of freezethaw cycles and load the beam specimens were tested in third-point loading condition. the load was realized using lever gears. the tensile stress ratio c was 0,0 (control specimens); 0,17 and 0,50 with respect to the failure stress. the arrangement of test stand was presented in fig. 1. the scaled material was collected from the top surface of specimen, which was subjected to tensile stress. the deicing salt solution was kept on the top of specimen thanks to the rubber sheet glued to all surfaces of the specimen except the test surface. the edge of the rubber sheet reached 20 mm above the test surface. top specimen surface (total area for every specimen was equal to 45000 mm2) was saturated with demineralized water during 72 hours. immediately before the specimens were placed in the freezing chamber, the demineralized water was replaced with 3% nacl solution. the freezing medium was prevented from evaporating by applying a flat polyethylene sheet. the loading devices with specimens were placed in freezing chamber. m. kosior-kazberuk 48 fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 o c to – 18 o c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles m n was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freeze-thaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 o c to 18 o c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor s ic k and the critical crack tip opening displacement ctod c were determined using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in three-point bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. a) b) fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 °c to – 18 °c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles mn was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freezethaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 °c to 18 °c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor m. kosior-kazberuk 48 fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 o c to – 18 o c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles m n was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freeze-thaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 o c to 18 o c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor s ic k and the critical crack tip opening displacement ctod c were determined using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in three-point bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. a) b) fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. and the critical crack tip opening displacement ctodc were determined 42 using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in threepoint bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. m. kosior-kazberuk 48 fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 o c to – 18 o c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles m n was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freeze-thaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 o c to 18 o c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor s ic k and the critical crack tip opening displacement ctod c were determined using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in three-point bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. a) b) fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. after the initial cycle, each loading and unloading cycle was finished in about 1 min. the test result is a loadcmod curve with several loading-unloading cycles. based on the load-cmod relation, the fracture parameters and young’s modulus can be calculated. the p-cmod curve was prepared for each specimen. typical test result (obtained for control concrete without aea) was presented in fig. 3. according to rilem recommendations (1990) the young’s modulus e is calculated from the equation effects of interaction of static load and frost on damage mechanism of concrete elements 49 after the initial cycle, each loading and unloading cycle was finished in about 1 min. the test result is a load-cmod curve with several loading-unloading cycles. based on the load-cmod relation, the fracture parameters and young’s modulus can be calculated. the p-cmod curve was prepared for each specimen. typical test result (obtained for control concrete without aea) was presented in fig. 3. fig. 3. typical experimental load-cmod plot according to rilem recommendations (1990) the young’s modulus e is calculated from the equation ],/[)(6 2 010 bdcvsae i α= (1) where c i is the initial compliance calculated from load-cmod plot (fig. 3), s, a 0 , d, b are geometrical characteristics of specimen. the critical effective crack length a c (a c = a 0 + stable crack growth at peak load) is determined from equation (1) for calculated value of young’s modulus and the unloading compliance c u measured at the maximum load (figure 3). using an iteration process, the critical effective crack length a c is found when equation (2) is satisfied: ],/[)(6 2 1 bdcvsae ucc α= (2) the critical stress intensity factor is calculated according to relationship ( ) ( ) , 2 5,03 2 1 max bd fas wpk ccs ic απ += (3) where p max – the measured maximum load, ,/ 0 lsww = and w0 – self-weight of the beam. the critical crack tip opening displacement is calculated as: ( ) ( ) ( )( )[ ] ,149,1081,11 )(5,06 2/1 2 1 2 2 11max ββαβ α −−+− + = c cc c bed vsawp ctod (4) in which c aa / 0 =β . in equations (1), (2), (3), (4) v 1 (α 0 ), v 1 (α c ), v 1 (α c1 ), f(α c1 ) are geometric functions, described in details by shah et al. (1995). simultaneously, the changes in compressive strength due to frost action were monitored, using cubic specimens 100×100×100 mm, subjected to the same freeze-thaw regime as specimens for fracture parameters testing. 3. results and discussion scaling resistance of concrete subjected to static load the test results for both non-air-entrained and air-entrained concretes are presented in fig. 4 and 5. the analysis of test results showed the significant influence of considered range of stress on the increase in mass of material scaled from the specimen surface subjected to cyclic freezing and thawing. the increased susceptibility to surface scaling was observed for both concretes, with and without air-entraining admixture, (1) where c i is the initial compliance calculated from load-cmod plot (fig. 3), s, a0, d, b are geometrical characteristics of specimen. effects of interaction of static load and frost on damage mechanism of concrete elements 49 after the initial cycle, each loading and unloading cycle was finished in about 1 min. the test result is a load-cmod curve with several loading-unloading cycles. based on the load-cmod relation, the fracture parameters and young’s modulus can be calculated. the p-cmod curve was prepared for each specimen. typical test result (obtained for control concrete without aea) was presented in fig. 3. fig. 3. typical experimental load-cmod plot according to rilem recommendations (1990) the young’s modulus e is calculated from the equation ],/[)(6 2 010 bdcvsae i α= (1) where c i is the initial compliance calculated from load-cmod plot (fig. 3), s, a 0 , d, b are geometrical characteristics of specimen. the critical effective crack length a c (a c = a 0 + stable crack growth at peak load) is determined from equation (1) for calculated value of young’s modulus and the unloading compliance c u measured at the maximum load (figure 3). using an iteration process, the critical effective crack length a c is found when equation (2) is satisfied: ],/[)(6 2 1 bdcvsae ucc α= (2) the critical stress intensity factor is calculated according to relationship ( ) ( ) , 2 5,03 2 1 max bd fas wpk ccs ic απ += (3) where p max – the measured maximum load, ,/ 0 lsww = and w0 – self-weight of the beam. the critical crack tip opening displacement is calculated as: ( ) ( ) ( )( )[ ] ,149,1081,11 )(5,06 2/1 2 1 2 2 11max ββαβ α −−+− + = c cc c bed vsawp ctod (4) in which c aa / 0 =β . in equations (1), (2), (3), (4) v 1 (α 0 ), v 1 (α c ), v 1 (α c1 ), f(α c1 ) are geometric functions, described in details by shah et al. (1995). simultaneously, the changes in compressive strength due to frost action were monitored, using cubic specimens 100×100×100 mm, subjected to the same freeze-thaw regime as specimens for fracture parameters testing. 3. results and discussion scaling resistance of concrete subjected to static load the test results for both non-air-entrained and air-entrained concretes are presented in fig. 4 and 5. the analysis of test results showed the significant influence of considered range of stress on the increase in mass of material scaled from the specimen surface subjected to cyclic freezing and thawing. the increased susceptibility to surface scaling was observed for both concretes, with and without air-entraining admixture, fig. 3. typical experimental load-cmod plot the critical effective crack length ac (ac = a0 + stable crack growth at peak load) is determined from equation (1) for calculated value of young’s modulus and the unloading compliance cu measured at the maximum load (figure 3). using an iteration process, the critical effective crack length ac is found when equation (2) is satisfied: effects of interaction of static load and frost on damage mechanism of concrete elements 49 after the initial cycle, each loading and unloading cycle was finished in about 1 min. the test result is a load-cmod curve with several loading-unloading cycles. based on the load-cmod relation, the fracture parameters and young’s modulus can be calculated. the p-cmod curve was prepared for each specimen. typical test result (obtained for control concrete without aea) was presented in fig. 3. fig. 3. typical experimental load-cmod plot according to rilem recommendations (1990) the young’s modulus e is calculated from the equation ],/[)(6 2 010 bdcvsae i α= (1) where c i is the initial compliance calculated from load-cmod plot (fig. 3), s, a 0 , d, b are geometrical characteristics of specimen. the critical effective crack length a c (a c = a 0 + stable crack growth at peak load) is determined from equation (1) for calculated value of young’s modulus and the unloading compliance c u measured at the maximum load (figure 3). using an iteration process, the critical effective crack length a c is found when equation (2) is satisfied: ],/[)(6 2 1 bdcvsae ucc α= (2) the critical stress intensity factor is calculated according to relationship ( ) ( ) , 2 5,03 2 1 max bd fas wpk ccs ic απ += (3) where p max – the measured maximum load, ,/ 0 lsww = and w0 – self-weight of the beam. the critical crack tip opening displacement is calculated as: ( ) ( ) ( )( )[ ] ,149,1081,11 )(5,06 2/1 2 1 2 2 11max ββαβ α −−+− + = c cc c bed vsawp ctod (4) in which c aa / 0 =β . in equations (1), (2), (3), (4) v 1 (α 0 ), v 1 (α c ), v 1 (α c1 ), f(α c1 ) are geometric functions, described in details by shah et al. (1995). simultaneously, the changes in compressive strength due to frost action were monitored, using cubic specimens 100×100×100 mm, subjected to the same freeze-thaw regime as specimens for fracture parameters testing. 3. results and discussion scaling resistance of concrete subjected to static load the test results for both non-air-entrained and air-entrained concretes are presented in fig. 4 and 5. the analysis of test results showed the significant influence of considered range of stress on the increase in mass of material scaled from the specimen surface subjected to cyclic freezing and thawing. the increased susceptibility to surface scaling was observed for both concretes, with and without air-entraining admixture, (2) the critical stress intensity factor is calculated according to relationship effects of interaction of static load and frost on damage mechanism of concrete elements 49 after the initial cycle, each loading and unloading cycle was finished in about 1 min. the test result is a load-cmod curve with several loading-unloading cycles. based on the load-cmod relation, the fracture parameters and young’s modulus can be calculated. the p-cmod curve was prepared for each specimen. typical test result (obtained for control concrete without aea) was presented in fig. 3. fig. 3. typical experimental load-cmod plot according to rilem recommendations (1990) the young’s modulus e is calculated from the equation ],/[)(6 2 010 bdcvsae i α= (1) where c i is the initial compliance calculated from load-cmod plot (fig. 3), s, a 0 , d, b are geometrical characteristics of specimen. the critical effective crack length a c (a c = a 0 + stable crack growth at peak load) is determined from equation (1) for calculated value of young’s modulus and the unloading compliance c u measured at the maximum load (figure 3). using an iteration process, the critical effective crack length a c is found when equation (2) is satisfied: ],/[)(6 2 1 bdcvsae ucc α= (2) the critical stress intensity factor is calculated according to relationship ( ) ( ) , 2 5,03 2 1 max bd fas wpk ccs ic απ += (3) where p max – the measured maximum load, ,/ 0 lsww = and w0 – self-weight of the beam. the critical crack tip opening displacement is calculated as: ( ) ( ) ( )( )[ ] ,149,1081,11 )(5,06 2/1 2 1 2 2 11max ββαβ α −−+− + = c cc c bed vsawp ctod (4) in which c aa / 0 =β . in equations (1), (2), (3), (4) v 1 (α 0 ), v 1 (α c ), v 1 (α c1 ), f(α c1 ) are geometric functions, described in details by shah et al. (1995). simultaneously, the changes in compressive strength due to frost action were monitored, using cubic specimens 100×100×100 mm, subjected to the same freeze-thaw regime as specimens for fracture parameters testing. 3. results and discussion scaling resistance of concrete subjected to static load the test results for both non-air-entrained and air-entrained concretes are presented in fig. 4 and 5. the analysis of test results showed the significant influence of considered range of stress on the increase in mass of material scaled from the specimen surface subjected to cyclic freezing and thawing. the increased susceptibility to surface scaling was observed for both concretes, with and without air-entraining admixture, (3) where pmax – the measured maximum load, ,/0 lsww = and w0 – self-weight of the beam. the critical crack tip opening displacement is calculated as: effects of interaction of static load and frost on damage mechanism of concrete elements 49 after the initial cycle, each loading and unloading cycle was finished in about 1 min. the test result is a load-cmod curve with several loading-unloading cycles. based on the load-cmod relation, the fracture parameters and young’s modulus can be calculated. the p-cmod curve was prepared for each specimen. typical test result (obtained for control concrete without aea) was presented in fig. 3. fig. 3. typical experimental load-cmod plot according to rilem recommendations (1990) the young’s modulus e is calculated from the equation ],/[)(6 2 010 bdcvsae i α= (1) where c i is the initial compliance calculated from load-cmod plot (fig. 3), s, a 0 , d, b are geometrical characteristics of specimen. the critical effective crack length a c (a c = a 0 + stable crack growth at peak load) is determined from equation (1) for calculated value of young’s modulus and the unloading compliance c u measured at the maximum load (figure 3). using an iteration process, the critical effective crack length a c is found when equation (2) is satisfied: ],/[)(6 2 1 bdcvsae ucc α= (2) the critical stress intensity factor is calculated according to relationship fas k s ic απ = (3) ( ) ( ) ( )( )[ ] ,149,1081,11 )(5,06 2/1 2 1 2 2 11max ββαβ α −−+− + = c cc c bed vsawp ctod (4) in which aa /= . 1 (α c ), v 1 (α c1 ), f(α c1 ) are geometric functions, described in details by shah et al. (1995). simultaneously, the changes in compressive strength due to frost action were monitored, using cubic specimens 100×100×100 mm, subjected to the same freeze-thaw regime as specimens for fracture parameters testing. 3. results and discussion scaling resistance of concrete subjected to static load the test results for both non-air-entrained and air-entrained concretes are presented in fig. 4 and 5. the analysis of test results showed the significant influence of considered range of stress on the increase in mass of material scaled from the specimen surface subjected to cyclic freezing and thawing. the increased susceptibility to surface scaling was observed for both concretes, with and without air-entraining admixture, × × effects of interaction of static load and frost on damage mechanism of concrete elements 49 after the initial cycle, each loading and unloading cycle was finished in about 1 min. the test result is a load-cmod curve with several loading-unloading cycles. based on the load-cmod relation, the fracture parameters and young’s modulus can be calculated. the p-cmod curve was prepared for each specimen. typical test result (obtained for control concrete without aea) was presented in fig. 3. fig. 3. typical experimental load-cmod plot according to rilem recommendations (1990) the young’s modulus e is calculated from the equation ],/[)(6 2 010 bdcvsae i α= (1) where c i is the initial compliance calculated from load-cmod plot (fig. 3), s, a 0 , d, b are geometrical characteristics of specimen. the critical effective crack length a c (a c = a 0 + stable crack growth at peak load) is determined from equation (1) for calculated value of young’s modulus and the unloading compliance c u measured at the maximum load (figure 3). using an iteration process, the critical effective crack length a c is found when equation (2) is satisfied: ],/[)(6 2 1 bdcvsae ucc α= (2) the critical stress intensity factor is calculated according to relationship fas k s ic απ = (3) ( ) ( ) ( )( )[ ] ,149,1081,11 )(5,06 2/1 2 1 2 2 11max ββαβ α −−+− + = c cc c bed vsawp ctod (4) in which aa /= . 1 (α c ), v 1 (α c1 ), f(α c1 ) are geometric functions, described in details by shah et al. (1995). simultaneously, the changes in compressive strength due to frost action were monitored, using cubic specimens 100×100×100 mm, subjected to the same freeze-thaw regime as specimens for fracture parameters testing. 3. results and discussion scaling resistance of concrete subjected to static load the test results for both non-air-entrained and air-entrained concretes are presented in fig. 4 and 5. the analysis of test results showed the significant influence of considered range of stress on the increase in mass of material scaled from the specimen surface subjected to cyclic freezing and thawing. the increased susceptibility to surface scaling was observed for both concretes, with and without air-entraining admixture, (4) in which caa /0=β . in equations (1), (2), (3), (4) v1(α0), v1(αc), v1(αc1), f(αc1) are geometric functions, described in details by shah et al. (1995). simultaneously, the changes in compressive strength due to frost action were monitored, using cubic specimens 100×100×100 mm, subjected to the same freeze-thaw regime as specimens for fracture parameters testing. 3. results and discussion scaling resistance of concrete subjected to static load the test results for both non-air-entrained and airentrained concretes are presented in fig. 4 and 5. the analysis of test results showed the significant influence of considered range of stress on the increase in a) b) (4) 43 mass of material scaled from the specimen surface subjected to cyclic freezing and thawing. the increased susceptibility to surface scaling was observed for both concretes, with and without air-entraining admixture, although, the dosage of aea assured very good scaling resistance for control unload concrete specimens. the influence of the tensile stress on scaling was observed after 14 cycles of the freezing and thawing. the differences in mass of material, scaled from specimens subjected to various stress levels, increased together with the number of cycles. besides, for specimens loaded the greater scatter of measurements was noticed. m. kosior-kazberuk 50 although, the dosage of aea assured very good scaling resistance for control unload concrete specimens. the influence of the tensile stress on scaling was observed after 14 cycles of the freezing and thawing. the differences in mass of material, scaled from specimens subjected to various stress levels, increased together with the number of cycles. besides, for specimens loaded the greater scatter of measurements was noticed. fig. 4. mean mass of scaled material m vs. freeze-thaw cycles number n as well as stress level c for non-air-entrained concrete fig. 5. mean mass of scaled material m vs. freeze-thaw cycles number n as well as stress level c for air-entrained concrete in case of the unloaded concrete specimens, after the initial rapid growth in mass of scaling, the slowdown of the process was observed and then the mass of scaling accumulated gradually. for loaded concrete specimens, the mass of the scaling increase was almost linear together with the number of cycles, for both stress levels. after 28 cycles the mass of scaled material for stress level c = 0,17 was ca. 30% greater, and for c = 0,50 twice greater in comparison to the scaling from unloaded concrete surface. after 56 cycles, the loss in material for lower stress level was twice greater and for higher stress – more than three times greater than the mass of scaling for unloaded concrete. in case of the air-entrained concrete, the greater relative difference in mass of material scaled from concrete subjected to load was pointed out in comparison to control concrete. the tensile stress level c = 0,17 caused four times increase and stress level c = 0,50 – five times increase in the amount of scaled material. however, the airentraining of concrete influenced the limitation of the susceptibility for scaling in comparison to the concrete without admixture. in considered range of external load of specimens in third point bending test, the rate of damage progress increased with the increase in applied stress value. considering the mass of scaled material after n cycles as a measure of accumulated damages, it is possible to evaluate the number of cycles after that, the scaling achieves unacceptable volume, for assessed stress level. unacceptable level of scaling can be determined arbitrarily, regarding durability requirements, or on the basis of standards for different concrete elements. the dependence can be useful for predicting concrete ability to scaling according to the tensile stress level. changes in fracture parameters of concrete due to cyclic freezing and thawing the fracture parameters were determined on the basis of p–cmod curves obtained for concrete specimens. the effect of freezing and thawing on concrete properties was referee to the results obtained for reference specimens cured in water. the force p plotted versus cmod measured for air-entrained concrete after 350 cycles and control concrete were presented in fig. 6. fig. 4. mean mass of scaled material m vs. freeze-thaw cycles number n as well as stress level c for non-air-entrained concrete m. kosior-kazberuk 50 although, the dosage of aea assured very good scaling resistance for control unload concrete specimens. the influence of the tensile stress on scaling was observed after 14 cycles of the freezing and thawing. the differences in mass of material, scaled from specimens subjected to various stress levels, increased together with the number of cycles. besides, for specimens loaded the greater scatter of measurements was noticed. fig. 4. mean mass of scaled material m vs. freeze-thaw cycles number n as well as stress level c for non-air-entrained concrete fig. 5. mean mass of scaled material m vs. freeze-thaw cycles number n as well as stress level c for air-entrained concrete in case of the unloaded concrete specimens, after the initial rapid growth in mass of scaling, the slowdown of the process was observed and then the mass of scaling accumulated gradually. for loaded concrete specimens, the mass of the scaling increase was almost linear together with the number of cycles, for both stress levels. after 28 cycles the mass of scaled material for stress level c = 0,17 was ca. 30% greater, and for c = 0,50 twice greater in comparison to the scaling from unloaded concrete surface. after 56 cycles, the loss in material for lower stress level was twice greater and for higher stress – more than three times greater than the mass of scaling for unloaded concrete. in case of the air-entrained concrete, the greater relative difference in mass of material scaled from concrete subjected to load was pointed out in comparison to control concrete. the tensile stress level c = 0,17 caused four times increase and stress level c = 0,50 – five times increase in the amount of scaled material. however, the airentraining of concrete influenced the limitation of the susceptibility for scaling in comparison to the concrete without admixture. in considered range of external load of specimens in third point bending test, the rate of damage progress increased with the increase in applied stress value. considering the mass of scaled material after n cycles as a measure of accumulated damages, it is possible to evaluate the number of cycles after that, the scaling achieves unacceptable volume, for assessed stress level. unacceptable level of scaling can be determined arbitrarily, regarding durability requirements, or on the basis of standards for different concrete elements. the dependence can be useful for predicting concrete ability to scaling according to the tensile stress level. changes in fracture parameters of concrete due to cyclic freezing and thawing the fracture parameters were determined on the basis of p–cmod curves obtained for concrete specimens. the effect of freezing and thawing on concrete properties was referee to the results obtained for reference specimens cured in water. the force p plotted versus cmod measured for air-entrained concrete after 350 cycles and control concrete were presented in fig. 6. fig. 5. mean mass of scaled material m vs. freeze-thaw cycles number n as well as stress level c for air-entrained concrete in case of the unloaded concrete specimens, after the initial rapid growth in mass of scaling, the slowdown of the process was observed and then the mass of scaling accumulated gradually. for loaded concrete specimens, the mass of the scaling increase was almost linear together with the number of cycles, for both stress levels. after 28 cycles the mass of scaled material for stress level c = 0,17 was ca. 30% greater, and for c = 0,50 twice greater in comparison to the scaling from unloaded concrete surface. after 56 cycles, the loss in material for lower stress level was twice greater and for higher stress – more than three times greater than the mass of scaling for unloaded concrete. in case of the air-entrained concrete, the greater relative difference in mass of material scaled from concrete subjected to load was pointed out in comparison to control concrete. the tensile stress level c = 0,17 caused four times increase and stress level c = 0,50 – five times increase in the amount of scaled material. however, the air-entraining of concrete influenced the limitation of the susceptibility for scaling in comparison to the concrete without admixture. in considered range of external load of specimens in third point bending test, the rate of damage progress increased with the increase in applied stress value. considering the mass of scaled material after n cycles as a measure of accumulated damages, it is possible to evaluate the number of cycles after that, the scaling achieves unacceptable volume, for assessed stress level. unacceptable level of scaling can be determined arbitrarily, regarding durability requirements, or on the basis of standards for different concrete elements. the dependence can be useful for predicting concrete ability to scaling according to the tensile stress level. changes in fracture parameters of concrete due to cyclic freezing and thawing the fracture parameters were determined on the basis of p–cmod curves obtained for concrete specimens. the effect of freezing and thawing on concrete properties was referee to the results obtained for reference specimens cured in water. the force p plotted versus cmod measured for air-entrained concrete after 350 cycles and control concrete were presented in fig. 6.effects of interaction of static load and frost on damage mechanism of concrete elements 51 fig. 6. p–cmod curves for air-entrained concrete after 350 cycles and reference concrete cured in water from the p–cmod plot, one can see that the initial part of the curve for reference concrete is almost linear and the strain of the notch tip under tension increases with increasing load. after the linear portion of p–cmod curve, deviation from linear response is observed and the tension strain reaches the maximum value, which indicates the onset of crack initiation at the tip of the notch. after the point of maximum tension, the curve exhibits increasing load until reaching the peak. therefore, the load at which the tension reaches its maximum value is the initial cracking load. for extremely damaged concrete, the linear portion of p–cmod curve is very short, the maximum load is achieved quickly, and the strain softening is observed. in the process of degradation the concrete behaviour is more ductile in comparison to reference concrete but the maximum load (p max ) is strongly limited. the fracture parameters s ic k and ctod c as well as the measured maximum load p max , the critical effective crack length a c related to depth of specimen d, young’s modulus e and compressive strength f cm determined for concrete without aea and for air-entrained concrete were presented in tables 1 and 2, respectively. the results for frozen as well as reference specimens were given. table 1. properties of concrete without air-entraining agent feature 90 cycles 150 cycles 200 cycles frozen reference frozen reference frozen reference p max [n] 3900 3850 4415 5100 4300 5000 a c /d [-] 0,397 0,412 0,446 0,458 0,438 0,433 s ic k [mn/m 3/2 ] 1,033 1,003 1,366 1,536 1,060 1,239 ctod c [m⋅10 -5 ] 1,377 1,403 1,758 1,763 2,014 1,428 e [mpa] 21015 24143 28125 35117 17092 36214 f cm [mpa] 66,0 61,8 50,1 65,8 37,5 67,8 the specimens of non-air-entrained concrete were subjected to 200 cycles of freezing and thawing. the fracture parameters undergo greater changes than compressive strength under frost attack. after initial slight improvement of properties, the fracture parameters were influenced by frost action. for frozen specimens the value of s ic k decreased and the ctodc increased, which means that the fracture process (stable crack propagation) appeared for greater crack opening displacement. after 150 cycles the reference concrete was characterized by higher critical stress intensity factor and higher value of young’s modulus than frozen concrete, but the values of ctod c were comparable for both of them. after 200 cycles significant decrease in the mechanical as well as fracture properties of concrete subjected to freezing and thawing was found. table 2. properties of concrete with air-entraining agent feature 200 cycles 350 cycles frozen reference frozen reference p max [n] 5230 5450 1750 5750 a c /d [-] 0,430 0,423 0,434 0,424 s ic k [mn/m 3/2 ] 0,763 0,841 0,274 0,887 ctod c [m⋅10 -5 ] 1,626 1,510 1,911 1,693 e [mpa] 31940 34080 9350 32190 f cm [mpa] 59,5 62,4 29,0 61,5 fig. 6. p–cmod curves for air-entrained concrete after 350 cycles and reference concrete cured in water from the p–cmod plot, one can see that the initial part of the curve for reference concrete is almost linear and the strain of the notch tip under tension increases with increasing load. after the linear portion of p–cmod curve, deviation from linear response is observed and the tension strain reaches the maximum value, which indicates the onset of crack initiation at the tip of the notch. after the point of maximum tension, the curve exhibits increasing load until reaching the peak. therefore, the load at which the tension reaches its maximum value is the initial cracking load. for extremely damaged concrete, the linear portion of p–cmod curve is very short, the maximum load is achieved quickly, and the strain softening is observed. in the process of degradation the concrete behaviour is more ductile in 44 comparison to reference concrete but the maximum load (pmax) is strongly limited. the fracture parameters and ctodc as well as the measured maximum load pmax, the critical effective crack length ac related to depth of specimen d, young’s modulus e and compressive strength fcm determined for concrete without aea and for air-entrained concrete were presented in tables 1 and 2, respectively. the results for frozen as well as reference specimens were given. the specimens of non-air-entrained concrete were subjected to 200 cycles of freezing and thawing. the fracture parameters undergo greater changes than compressive strength under frost attack. after initial slight improvement of properties, the fracture parameters were influenced by frost action. for frozen specimens the value of m. kosior-kazberuk 48 fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 o c to – 18 o c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles m n was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freeze-thaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 o c to 18 o c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor s ic k and the critical crack tip opening displacement ctod c were determined using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in three-point bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. a) b) fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. decreased and the ctodc increased, which means that the fracture process (stable crack propagation) appeared for greater crack opening displacement. after 150 cycles the reference concrete was characterized by higher critical stress intensity factor and higher value of young’s modulus than frozen concrete, but the values of ctodc were comparable for both of them. after 200 cycles significant decrease in the mechanical as well as fracture properties of concrete subjected to freezing and thawing was found. table 2. properties of concrete with air-entraining agent feature 200 cycles 350 cycles frozen reference frozen reference pmax [n] 5230 5450 1750 5750 ac /d [-] 0,430 0,423 0,434 0,424 m. kosior-kazberuk 48 fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 o c to – 18 o c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles m n was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freeze-thaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 o c to 18 o c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor s ic k and the critical crack tip opening displacement ctod c were determined using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in three-point bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. a) b) fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. [mn/m3/2] 0,763 0,841 0,274 0,887 ctodc [m×10-5] 1,626 1,510 1,911 1,693 e [mpa] 31940 34080 9350 32190 fcm [mpa] 59,5 62,4 29,0 61,5 the specimens of air-entrained concrete were subjected to 350 cycles. the results presented in table 2 show similar changes in fracture parameters to the concrete without aea. the concrete microstructure deterioration due to freezing caused the decrease in the maximum load, critical stress intensity factor, young’s modulus and the increase in the critical crack tip opening displacement. generally, the air-entrained concrete is characterized by smaller value of m. kosior-kazberuk 48 fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 o c to – 18 o c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles m n was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freeze-thaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 o c to 18 o c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor s ic k and the critical crack tip opening displacement ctod c were determined using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in three-point bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. a) b) fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. than non-air-entrained concrete. table 1. properties of concrete without air-entraining agent feature 90 cycles 150 cycles 200 cycles frozen reference frozen reference frozen reference pmax [n] 3900 3850 4415 5100 4300 5000 ac /d [-] 0,397 0,412 0,446 0,458 0,438 0,433 m. kosior-kazberuk 48 fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 o c to – 18 o c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles m n was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freeze-thaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 o c to 18 o c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor s ic k and the critical crack tip opening displacement ctod c were determined using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in three-point bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. a) b) fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. [mn/m3/2] 1,033 1,003 1,366 1,536 1,060 1,239 ctodc [m×10-5] 1,377 1,403 1,758 1,763 2,014 1,428 e [mpa] 21015 24143 28125 35117 17092 36214 fcm [mpa] 66,0 61,8 50,1 65,8 37,5 67,8 the air-void system resulting from air-entraining treatment forms additional pores in concrete microstructure, which are the stress concentrators responsible for fracture. even though the concrete is recognized to be quasibrittle material (gettu et al. 1990), in the process of degradation the material showed more ductile characteristics than reference concrete. through experimental study presented, it was found that steady crack propagation stage exist before unstable fracture. the longer critical effective crack length ac and greater value of ctodc, needed for failure, is characteristic for damage concrete. similar changes in concrete behavior were noticed by hanjari et al. (2011) during bond properties examination and by li et al. (2011) during testing the flexural fatigue influence on concrete frost resistance. conclusions two types of concrete damage due to cyclic freezing and thawing were studied. the interaction of load and freeze-thaw cycles with chloride exposure regime on surface scaling process of concrete was analyzed. the internal cracking progress in concrete was characterized using fracture parameters. the tests were carried on for nonair-entrained as well as for air-entrained concretes. as the results of investigations, it was found that interaction of load and cyclic freezing and thawing in the presence of de-icing salt accelerates the process of surface scaling of concrete. in considered range of stress subjected to beams in three-point bending test, the rate of damages accumulation increased with the increase in stress, but the rate of damage accumulation was changing during longterm test. the complete p–cmod curves were measured from fracture tests on both frozen and reference concrete specimens. the fracture parameters of concrete were strongly influenced by cyclic freezing and thawing. it was found that the material damaged, due to cyclic freezing and thawing, is more ductile than undamaged one. the critical stress intensity factor and crack tip opening displacement can be valuable measures described the concrete degradation due to accumulation of physical damages in its microstructure. acknowledgements minister of science and higher education has supported the research work presented in this paper, project number s/wbiis/2/12. 45 references bažant, z. p. 2002. concrete fracture models: testing and practice. engineering fracture mechanics, 69, 165-205. cao, j., chung, d. d. l. 2002. damage evolution during freezethaw cycling of cement mortar, studied by electrical resistivity measurement. cement and concrete research, 32, 1657-1661. ceb-fip model code 2010 final draft. fagerlund, g. 2002. mechanical damage and fatigue effects associated with freeze-thaw of materials. in proc of 2nd international rilem workshop on frost resistance of concrete, essen, 18-19 april 2002, 117-132. gettu, r., bažant, z. p., karr, m. e. 1990. fracture properties and brittleness of high-strength concrete. aci materials journal, 6, 608-618. hanjari, k. z., utgenannt, p., lundgren, k. 2011. experimental study of the material and bond properties of frost-damaged concrete. cement and concrete research, 41, 244-254. hasan, m., ueda, t., sato, y. 2008. stress-strain relationship of frost-damaged concrete subjected to fatigue loading. journal of materials in civil engineering, 1, 37-45. jana, d. 2004. concrete, construction or salt – which causes scaling? concrete international, 11, 31-38. jenq, y. s., shah, s. p. 1985. a two parameter fracture model for concrete. journal of engineering mechanics, 111, 1227-1241. jenq, y-s., shah, s. p. 1991. features of mechanics of quasibrittle crack propagation in concrete. international journal of fracture, 51, 103-120. li, w., sun, w., jiang, j. 2011. damage of concrete experiencing flexural fatigue load and closed freeze/thaw cycles simultaneously. construction and building material, 25, 2604-2610. penttala, v. 2006. surface and internal deterioration of concrete due to saline and non-saline freeze-thaw loads. cement and concrete research, 36, 921-928. pigeon, m., marchand, j., pleau, r. 1996. frost resistant concrete. construction and building materials, 10, 339-348. pkn-cen/ts 12390-9:2007 testing hardened concrete – part 9: freeze-thaw resistance – scaling. rilem committee on fracture mechanics of concrete – test methods: determination of the fracture parameters ( m. kosior-kazberuk 48 fig. 1. sketch of specimen subjected to three-point bending test the single cycle duration was 24 hours with temperature change from 20 o c to – 18 o c. every 7 days nacl solution was exchanged. the material that scaled from the test surface was collected and dried to constant weight. the amount of the scaled material per unit area after n cycles m n was evaluated for each measuring occasion and each specimen. the specimens were subjected to 56 freeze-thaw cycles, the number suggested for unmodified concrete. fracture parameters determination the specimens for fracture parameters evaluation were subjected to cyclic freezing in air and thawing in water. the temperature changed from -18 o c to 18 o c. the duration of single cycle was 8 hours and the freezing period duration was 6 hours. the freezing and thawing process was finished 1 day before testing. the critical stress intensity factor s ic k and the critical crack tip opening displacement ctod c were determined using procedure described in rilem draft recommendation (1990), based on the fracture model elaborated by jenq and shah (1985). the fracture parameters were assessed in three-point bend test on beams with initial notches. the specimen sizes were 100×100×400 mm, and the initial saw-cut notch depth was equal to 30 mm and width was 3 mm. the geometry of specimen and the way of load were presented in fig. 2a. each series was composed of 4 replicates. a) b) fig. 2. fracture testing configuration and geometry of specimen: (a) the way of load; (b) the place of cmod measurement the closed-loop testing machine with crack mouth opening displacement (cmod) as the feedback signal was used to achieve a stable failure. the crack mouth opening displacement and the applied load were recorded continuously during the test. the cmod, indicated in fig. 2b, was measured by means of clip gauge. to measure the crack mouth opening displacement (cmod) a pair of knife edges was attached to two sides of a notch performed on the lower surface of the beam. the rate of loading was controlled by a constant rate of increment of cmod so that the peak load was reached in 5 min. the beam was monotonically loaded up to the maximum load. the applied load was reduced after the load passed the maximum value and was at about 95% of the peak load. then, the applied load was reduced to zero and the reloading was applied. the specimen was cyclically loaded up to failure. and ctodc) of plain concrete using three-point bend tests. materials and structures, 23, 1990, 457-460. schlangen, e., garboczi, e. j. 1997. fracture simulations of concrete using lattice models: computational aspects. engineering fracture mechanics, 57, 319-332. şahmaran, m., li, v. c.: de-icing salt scaling resistance of mechanical loaded engineered cementitious composites. cement and concrete research, 37, 1035-1046. shah, s. p., swartz, s. e., ouyang, ch. 1995. fracture mechanics of concrete: applications of fracture mechanics to concrete, rock and other quasi-brittle materials. john wiley & sons, inc., new york. sun, w., zhang, y. m., yan, h. d., mu, r. 1999. damage and damage resistance of high strength concrete under the action of load and freeze-thaw cycles. cement and concrete research, 29, 1519-1523. valenza ii, j. j., scherer, g. w.: a review of salt scaling: i. phenomenology. cement and concrete research, 37, 1007-1021. wang, j. j-a., liu, k.c., naus, d. 2010. a new method for determining the fracture toughness of concrete materials. cement and concrete research, 40, 497-499. yu, h., sun, w., zhang, y. m., guo, l., li, m.: durability of concrete subjected to the combined actions of flexural stress, freeze-thaw cycles and bittern solutions. journal of wuhan university of technology, 6, 893-900. zhou, y., cohen, m. d., dolch, w. l. 1994. effect of external loads on the frost-resistant properties of mortar with and without silica fume. aci materials journal, 6, 595-601. received 2012 06 04 accepted after revision 2012 09 03 marta kosior-kazberuk – associate professor at bialystok university of technology, faculty of civil and environmental engineering, department of building structures. main research area: concrete and reinforced concrete structures, durability of building materials and structures with emphasis on assessment methods, sustainable development in concrete technology. address: wiejska 45e, 15-351 bialystok, poland. tel.: +48 85 746 96 94 e-mail: m.kosior@pb.edu.pl 85 journal of sustainable architecture and civil engineering 2022/2/31 *corresponding author: amela@uniwa.gr effects of the covid -19 pandemic on the use and attitudes towards urban public spaces received 2022/06/01 accepted after revision 2022/09/27 journal of sustainable architecture and civil engineering vol. 2 / no. 31 / 2022 pp. 85-95 doi 10.5755/j01.sace.31.2.31545 effects of the covid -19 pandemic on the use and attitudes towards urban public spaces jsace 2/31 http://dx.doi.org/10.5755/j01.sace.31.2.31545 athina mela*, george varelidis laboratory of urban planning and architecture, department of civil engineering, school of engineering, university of west attica, 250 thivon & p.ralli str., 12241 athens, greece introduction abstract the benefits of interaction with urban public space, particularly green spaces are numerous for citizens, especially those who live in metropolitan areas. the outbreak of the pandemic, as well as the restrictive measures put in place to prevent the virus’s spread, caused enormous changes in people’s daily lives and activities. using a structured questionnaire, the current study intends to capture the shift in attitudes and perceptions of residents of the attica region during the 2nd wave of restriction measures (7/11/20 – 3/7/21). during the pandemic, visitation in urban public spaces increased, according to the data. the great majority of participants preferred to visit mostly urban public areas within walking distance of their residence (up to 15 minutes), especially in the afternoon and relatively frequently, with 45 percent claiming to visit them “daily” or “3-4 times a week,” and only 3% claiming “never”. the analysis showed an increase in the visits during the pandemic from participants who reported better-perceived quality of the spaces, better accessibility, safety during the day, and a feeling of relaxation in the free public spaces of their area. additionally, those reported living in areas with many available spaces were more likely to increase the frequency of visits during the pandemic. keywords: covid -19, green spaces, public spaces, urban mobility. the urban public space consisted of streets, parks, squares, and playgrounds that are designed for public use by the community’s residents. the morphology of cities is changing as a result of ever-intensifying and rising urbanization, often leading to quick degradation of urban public space and a reduction in vegetation in cities (jayasinghe, hemakumara, and hewage 2021). the covid-19 pandemic was not only a global public health emergency but also had a significant impact on global social cohesiveness and urban sustainability (addas and maghrabi 2022). numerous studies have shown that the presence of sufficient quality and quantity of urban green space, as a primary element of the city system, is critical in defining a high standard of life in large urban centers. green spaces and parks in cities are important for preserving the microclimate, improving soil fertility, and increasing the overall urban resilience (lee and kim 2015). also, urban public space engagement has been found to have a significant positive impact on citizens’ health as well as their social growth and interaction (burnett et al. 2021). this has resulted in a renewed emphasis on public space and the significance of long-term management (glavan et al. 2022). journal of sustainable architecture and civil engineering 2022/2/31 86 ιn order to reduce the spread of the pandemic, the greek government imposed a series of emergency regulations aimed at restricting mobility and preventing crowding. social distance measurements have restricted a variety of social, economic, and educational activities, as well as residents’ mobility. repeated lockdowns also had an impact on working conditions. measurements such as the implementation of teleworking, shift work, and the gradual arrival of employees were encouraged and implemented to relieve traffic on public transportation (campisi et al. 2020; noszczyk, gorzelany, and kukulska-kozie 2022). also, global trends in access and usage of urban public spaces are continually shifting (honey-rosés, anguelovski, bohigas et al. 2020). the greek government has discouraged access to and usage of public spaces, especially urban parks, and squares, throughout numerous phases of the pandemic due to repeated lockdowns enforced to control the virus’s spread. there were periods when only the most urgent of reasons could justify leaving home (work, helping a familiar person, a short walk for physical activity on the borders of the municipality, etc) (politis et al. 2021). the discouragement of citizens from visiting and staying in open public spaces, particularly parks, has posed challenges to urban environments and citizen activity. to prevent health hazards, the number of park visitors decreased substantially in many cities during the strict lockdowns. several studies have found that free public spaces and especially urban parks are important for pandemic mitigation because they allow people to engage in outdoor activities while reducing the risk of virus infection (ugolini et al. 2020; addas and maghrabi 2022). as a result of the literature research, it was discovered that the new reality of the pandemic had a substantial impact on individuals’ attitudes about public space, particularly urban green areas, squares, and playgrounds (nikolaidou 2019; venter et al. 2021). in greece, only a few studies have been conducted to investigate the impact of the pandemic on residents’ attitudes toward free public spaces (kehagia et al. 2020; vatavali et al. 2020). taking into account this research gap, the goal of this study was to examine the impact of the covid-19 pandemic on the use and visitation of open urban areas in attica, greece’s most populated region, from a variety of perspectives. the current study is part of a larger examination of data from multidisciplinary research on public space and the impact of the pandemic on citizens’ physical and mental health. because of the vast amount of data and the nature of the research, it was decided that the current study would only look into (a) how mobility and visitation in free urban public spaces changed during the pandemic, (b) why residents chose to visit free public spaces during the pandemic, and (c) the possible relationship between urban characteristics of free public spaces and visitation. the current study can help with spatial, urban, and comparative analyses of public space strategically. furthermore, establishing conclusions regarding residents’ attitudes about the city’s public infrastructure might aid decision-makers in better understanding the importance and universality of urban public spaces in meeting human needs. as a result, in a post-pandemic future, a sustainable redesign of their public space may become more viable. this cross-sectional survey took place in athens, greece from 27 april to 27 june 2021, during the second wave of restriction measures (i.e., curfew, social distancing measures, etc ). the sample consisted of 745 residents of attica, greece, aged over 18 years old whose participation was voluntary and consensual, and answers were self-reported after the provision of detailed information about the nature and the scope of the research by the researchers. for the needs of the present study, convenient and snowball sampling techniques were used. the sample was recruited through invitation via personal e-mails and social media posts on facebook and instagram. questionnaires were distributed to each participant separately, while some participants forwarded the questionnaire to their friends and family. methods 87 journal of sustainable architecture and civil engineering 2022/2/31 tool and measures for this survey, a questionnaire was created consisting of questions that were frequently requested in this scientific field during the pandemic time, such as vatavali et al. 2020, and xie et al, 2020. sociodemographic measures were collected, including gender, ethnicity, age, place of residence, marital status, having children, house size (square footage), educational status, occupation, and annual income. characteristics of public spaces referred to quantity (i.e., “there are many free public spaces (squares, parks, playgrounds, groves, etc.) in your area”), quality (i.e., “the quality of free public spaces in your area is very good”), safety during day and night (i.e., “free public spaces in your area provide a sense of security during the day/night”), maintenance (i.e., “free public spaces in your area are well maintained”), mobility information (i.e., “your visits in public spaces in your area have decreased due to the pandemic”), etc. answers were collected either through a likert-type scale ranging from 1 (strongly disagree) to 5 (strongly agree) or from close-ended questions of multiple choices. statistical analysis spss, pasw statistics 18, was used for the statistical analysis. for quantitative variables, relative and absolute frequencies were used. multivariable logistic regression analysis was used to examine associations between the frequency of visits to free public spaces and their availability, quality, accessibility, maintenance, safety during the day, safety during the night, and feeling of relaxation, as well as age, gender, education level, employment status and having children. multiple linear regression was used to estimate the relationship between the decrease in the frequency of visits to free public spaces during the period of the covid-19 pandemic and their availability, quality, accessibility, maintenance, safety during the day, safety during the night, and feeling of relaxation, as well as age, gender, working hours and having children. the independent variables of both linear and regression models were established using a stepwise method. initially, all variables were included in each model, and then progressively removed until reaching the best predictive adequacy of the model. statistical significance was set at p <0.05. results survey responders in total, 745 people from the attica region participated in the questionnaire survey. over 72.3% identified as female, 26.6% as male, and 1.1% as “other”. over 98.9% identified as greek and 1.1% chose another ethnicity. nearly half of the responders (49.5%) belonged to the age group 18 – 30, 23.6% were 31-40 years old, 14.6% were 41-50 years old and 3% were above 60 years old. the lower household income classes represented in the data were <10,000 euros annually (42%) and the highest >30,000 euros annually (4.8%). almost 58.4% had completed a bachelor degree and 30.3% had completed a master degree or ph.d. only 21.1% of the people who participated had children. almost 35.3% came from the central sector of athens, 17.2% from the southern sector of athens, 14.5% from the northern sector of athens, 12.3% from the western sector of athens, 8.6% from piraeus regional unit, 6.3% from east attica regional unit and 5.8% form west attica regional unit. the pattern of urban public spaces visitation the patterns that follow citizens’ visits to urban public spaces during the pandemic were divided into four sections: frequency of urban public space visits during the week (fig. 1), the time spent going to the urban public destination (square, park, grove, playground) from their home (fig. 2), the preferred period during the day for this visit (fig. 3), and finally the type of activities for which they chose to visit the urban public spaces during the pandemic (fig. 4). the findings revealed that the vast majority of participants use the urban public places in their area, with 13% responding they visit them “every day,” 32 % responding “3-4 times a week,” 32 % stating “twice a week,” 16 % stating “once a week,” and 3 % claiming “none.” journal of sustainable architecture and civil engineering 2022/2/31 88 variable categories n (total=745) % gender male 198 26.6 female 539 72.3 other 8 1.1 ethnicity greek 737 98.9 other 8 1.1 age 18-30 369 49.5 31-40 176 23.6 41-50 109 14.6 51-60 69 9.3 >60 22 3 residency northern sector of athens 108 14.5 western sector of athens 92 12.3 central sector of athens 263 35.3 southern sector of athens 128 17.2 east attica regional unit 47 6.3 west attica regional unit 43 5.8 piraeus regional unit 64 8.6 marital status not married 323 43.4 married 150 20.1 in a relationship 232 31.1 divorced 25 3.4 table 1 socio-demographic characteristics of survey responders variable categories n (total=745) % marital status widowed 5 0.7 na/other 10 1.3 having children yes 157 21.1 no 583 78.3 na/other 5 0.7 age of children <18 102 65 education status primary/se condary school 5 0.7 high school 79 10.6 university/ college 435 58.4 msc/phd 226 30.3 occupation state employee 87 11.7 private employee 335 45 freelance 127 17 occupation unemployed 147 19.7 retired 22 3 na/other 27 3.6 income (yearly) <10,000 313 42 10,000-20,000 235 31.5 20,000-30,000 64 8.6 >30,000 36 4.8 na/other 97 13 it’s also clear that well over half of the residents preferred to be within walking distance of their homes, with 18% saying it takes less than 5 minutes, 48 % saying it takes 5 to 15 minutes, 21 % saying it takes 15 to 25 minutes, 7 percent saying it takes 25-35 minutes, and only 4% saying it takes more than 35 minutes. these findings are in complete agreement with government recommendations to avoid long-distance travel between municipalities to limit the possibility of congestion in inter-municipal centers of interest as well as the transmission of viral load from heavy regions to lighter ones. when questioned what period during the day they prefer to visit the urban public places, 66 % answered “after 18.00,” 25 % answered “14.00-18.00,” 13 % answered “12.00-14.00,” 19 % answered “9.00 -12.00,” and 3 % answered, “before 09.00.” 89 journal of sustainable architecture and civil engineering 2022/2/31 fig. 1 frequency of urban public space visits during the week 3% 16% 32% 32% 13% 0% 5% 10% 15% 20% 25% 30% 35% none 1 day 2 days 3-4 days every day frequency per week fig. 2 time spent going to the urban public destination (square, park, grove, and playground) 18% 48% 21% 7% 4% 0% 10% 20% 30% 40% 50% 60% < 5 min 5-15 min 15-25 min 25-35 min >35 min cost time 3% 19% 13% 25% 66% 0% 10% 20% 30% 40% 50% 60% 70% before 09.00 09.00-12.00 12.00-14.00 14.00-18.00 after 18.00 period fig. 3 the preferred period during the day for this visit frequency per week cost time journal of sustainable architecture and civil engineering 2022/2/31 90 87% 37% 13% 9% 27% 25% 49% 11% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% use of free public spaces fig. 4 type of activities for which they chose to visit the urban public spaces during the pandemic in addition, respondents were given the option of responding to a multiple-choice question on the motivations that drive them to be in urban public spaces during the pandemic. the vast majority of the sample (87%) chose “for a walk,” followed by 49% “to meet friends,” 37% “to feel close to nature,” 27% “for physical exercise,” 25% “to walk the pet,” 13% “accompany a family member,” 11% “for a picnic,” and 9% “for biking,” according to the results (fig. 4). relationship between urban characteristics of free public spaces and visitation the univariate linear regression analysis showed an increase in the visit to urban public spaces during the pandemic among participants who reported better-perceived quality (b=0.13, p=0.02), accessibility (b=0.16, p=0.01), safety during the day (b=0.16, p<0.01) and feeling of relaxation (b=0.28, p<0.01). additionally, those reported living in areas with many available free public spaces were more likely to increase the frequency of visits during the pandemic (b=0.06, p<0,01). an increase in the visit to free public spaces was also found in employed individuals (b=0.06, p=0.01), as well as in those with a higher education degree (b=0.06, p=0.03). on the contrary, those having children were less likely to increase the frequency of visits (b=-0.08, p<0.01). also, people older than 60 years of age were less likely to increase their visits to free public spaces during the pandemic compared to those aged 18-30 years (b=-0.16, p<0.01). use of free public spaces the rise of the pandemic has proved the significance of sustainable planning and maintenance of public spaces for residents, particularly in big urban areas. the pandemic has remained a visible and ever-changing threat to people until now, with no evidence of a decisive escalation of the health threat. its consequences may be seen in the public space in a variety of ways, and it is expected to create new conditions for public space management and planning. the covid-19 pandemic revealed the vulnerabilities of greek public space, particularly in the region of attica (vatavali et al. 2020). the current study investigated 745 individuals in the attica region, which is host to greece’s capital and contains the majority of the country’s heavily populated districts. the survey gathered information on the people of attica’s perceptions of public spaces. the findings revealed that the great majority of individuals prefer a) free public spaces that are within walking distance of their house, i.e. up to 15 minutes, which is in line with government restrictions. during this time, there were suggestions and restrictions for brief mobility in regions adjacent to the residence and inside the municipality’s boundaries. this is also in line with comparable research and polls undertaken in cities across discussion 91 journal of sustainable architecture and civil engineering 2022/2/31 table 2 univariate linear regression analysis between urban characteristics of free public spaces and visitation b std. error p-value quality 0.13 0.06 0.02 accessibility 0.16 0.06 0.01 maintenance 0.02 0.05 0.62 safety during day 0.16 0.06 0.00 safety during night 0.07 0.04 0.07 relaxation 0.28 0.05 0.00 availability of free public spaces not many available (ref.) (ref.) (ref.) many available 0.06 0.02 0.00 gender male (ref.) (ref.) (ref.) female 0.03 0,02 0,21 age 18-30 (ref.) (ref.) (ref.) 31-40 -0.04 0.02 0.10 41-50 -0.03 0.03 0.29 51-60 -0.05 0.03 0.106 >60 -0.16 0.05 0.00 having children no (ref.) (ref.) (ref.) yes -0.08 0.02 0.00 employment status unemployed (ref.) (ref.) (ref.) employed 0.06 0.02 0.01 b std. error p-value education status basic education (ref.) (ref.) (ref.) higher education 0.06 0.03 0.03 area of residency north (ref.) (ref.) (ref.) west 0.04 0.03 0.23 central 0.04 0.03 0.20 south 0.05 0.03 0.13 east 0.04 0.04 0.31 west attica -0.03 0.04 0.43 pireus -0.05 0.04 0.18 distance from fps <=15 min (ref.) (ref.) (ref.) 15-25 min 0.00 0.02 0.88 >25 min -0.06 0.03 0.05 house sqm <30 (ref.) (ref.) (ref.) 30-50 0.02 0.06 0.69 50-70 0.03 0.06 0.61 70-100 -0.02 0.05 0.72 >100 -0.01 0.06 0.86 working hours due to covid-19 same (ref.) (ref.) (ref.) less 0.02 0.03 0.60 more -0.02 0.02 0.36 europe during the pandemic, which revealed individuals’ preference for urban public spaces near their homes (xie et al. 2020; ugolini et al. 2020). we may claim that a sustainable urban design in the post-pandemic period should contain an extended network of public spaces and green spaces, even before we look at the quality concerns, which provide us with even more information about the importance of these places. as a result, it will enable urban dwellers to be within walking distance of such a destination. this is a major premise of the “city of ten minutes”, the “green city” theory, and the concept of urban acupuncture (honey-rosés, anguelovski, chireh et al. 2020; van vliet et al. 2021). the number of visits to the urban public spaces increased throughout the pandemic period, with journal of sustainable architecture and civil engineering 2022/2/31 92 more than 40% of respondents visiting the free urban areas several times a week, according to the findings as has been found in other relevant studies worldwide (derks, giessen, and winkel 2020; grima et al. 2020). of course, the new data and requirements that emerge as a result of pandemics are likely to change the demands for the distribution and organization of public places within the urban fabric (honey-rosés, anguelovski, bohigas, et al. 2020). the increasing visitation in these areas, as evidenced by other surveys, confirms the high need for local green spaces or neighborhood parks that serve as destinations for a variety of activities essential to everyone’s health and socializing. the number of inhabitants who chose to walk and exercise in public places is high, which is consistent with worldwide research. the focus on walking is most likely connected to the pandemic’s negative impact on residents’ physical and mental health, which directly explains people’s aim to attend public areas more frequently from this perspective. the frequency of visits by residents is increasing, and the phenomenon of certain inhabitants visiting the locations almost every day is highlighted (chen et al. 2022). in light of the pandemic, new designs are being considered that will favor uses and practices that will work best in pandemic distancing conditions, such as creating more space for personalized leisure and sports activity instead of team sports and places that encourage crowding, the development of smart applications that will recognize the need for periodic cleaning and sanitizing of urban equipment based on visitation data collection, expanding roads and pathways to make it easier for pedestrians to move and engage in safe sports activities such as jogging and running, etc (sun 2020; honey-rosés, anguelovski, chireh, et al. 2020; ugolini et al. 2020). one of the major goals of the study was to determine how residents’ participation in urban public places changed when the covid-19 regulations were implemented. several surveys have been conducted across european countries with very interesting results, such as the fact that during the first wave of the pandemic, nearly two-thirds of those who had frequently visited urban green spaces, stopped visiting them. this result can be attributed to government restrictions, while 1/3 continued to visit urban green spaces, a fact that condemns the human need for interaction with public space is indisputable even in the most adverse conditions (ugolini et al. 2020). during the pandemic, participants who reported improved perceived quality, better accessibility, developed a sense of security during the day and a sense of relaxation during their stay in these spaces, increased their visits, according to univariate linear regression analysis. this is in line with study findings, which suggest that good quality public open spaces, as well as a sense of relaxation and satisfaction while visiting them, are a strong motivator for citizens’ mobility (madureira et al. 2018; ernawati, surjono, and sudarmo 2018; sepe 2021; wu et al. 2015; zhang, cao, and han 2021). also, the findings suggest that changes in visitor behavior, particularly the choice of urban space visits for socializing purposes, show the significance of public space to citizens’ harmonious social development (mccormack et al. 2010). furthermore, individuals who said they lived in a location with a lot of available urban public spaces were more likely to increase their visit frequency during the pandemic (grima et al. 2020). those with children, on the other hand, were less inclined to increase the number of visits (fitzpatrick, drawve, and harris 2020; yamazaki et al. 2021; derks, giessen, and winkel 2020; uchiyama and kohsaka 2020). this emphasizes the evident need to encourage individuals with children to use public places in cities more frequently, therefore making them more child-friendly. the same phenomenon happened to persons over 60, who were less likely than those aged 18-30 to increase their visits during the pandemic (burnett et al. 2021). as a result, public space cannot be built solely to meet the requirements of certain groups, as this contradicts the notion of public space as a space for all (mela 2022; venter et al. 2021; 2020; yi et al. 2021). a more in-depth examination of the issues concerning the unique features of public space, as well as their interaction with individuals’ perceptions about them, is considered important. a potential area of research might be how the specific characteristics of the spaces can be factors of attraction for the residents, while at the same time, in times of public health crisis, this attractiveness can be an exacerbating factor in terms of, for example, viral load. it is considered appropriate in the management issues that arise 93 journal of sustainable architecture and civil engineering 2022/2/31 in relevant circumstances: a) to spread knowledge about the beneficial effects of citizen interaction with the public space, particularly during times of social distancing; b) to strengthen citizens’ awareness of the safest ways to use public space; c) to facilitate thoughtful planning and management of existing public spaces, eliminating the gap generated by urban space deterioration by emphasizing the diversity and local characteristics of public space, and significantly improving urban equipment; and d) to demonstrate continuous evaluation and re-checking of the condition of public spaces at the local level by competent agencies in order to constantly adapt to new data and citizens’ requirements (chen et al. 2022). the findings of this study are intended to aid in a better understanding of citizens’ patterns of activity in urban public areas throughout the pandemic time. the present study focused on the investigation of visitation patterns and the analysis of the elements that may have influenced them, which was undertaken on inhabitants of attica during the second wave of the pandemic and studied the probable benefits of their connection with the urban public space. the data analysis revealed that the number of visitors to open public places rose throughout the pandemic period, with the great majority of the sample visiting them multiple times during the week, particularly in the afternoon. leisure, exercise, and socializing are all factors in how they choose to spend their time in parks, squares, and playgrounds of their city. in addition, the sample revealed a definite preference for regions that are within walking distance of it (up to 15 minutes away). one of the study’s key findings is that people who reside in places with more and better urban public spaces are more inclined to visit them in the future. this emphasizes the need of having many, high-quality, secure, and easily accessible public urban spaces in every community, particularly during times of crisis. a resilient and sustainable society that can rapidly and efficiently overcome crises requires the design of a sustainable 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https://doi. org/10.3390/su13031558 mela athina phd candidate uniwa, civil engineer (msc), scientific associate laboratory of urban planning and architecture, school of engineering, department of civil engineering, university of west attica main research area sustainable urban design, urban public spaces, urban green spaces, resilient built environment, participatory design, urban adaptation. address university of west attica, 250 thivon & p.ralli str., 12241 athens, greece e-mail: mela.athina.civeng@gmail.com, amela@uniwa.gr about the authors varelidis george professor (architect engineer n.t.u.a. – urban planner) head of the department of civil engineering school of engineering, university of west attica main research area urban planning, urban renovations, environmental planning, architectural design and construction technology, spatial planning. address university of west attica, 250 thivon & p.ralli str., 12241 athens, greece e-mail: gvarel@uniwa.gr this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). journal of sustainable architecture and civil engineering 2023/1/32 172 environmental impact analysis of functional retrofitting measures in buildings received 2021/12/22 accepted after revision 2022/09/23 environmental impact analysis of functional retrofitting measures in buildings jsace 1/32 sushil kumar solanki* school of planning and architecture, new delhi, india rishabh rastogi savills property services (india) private limited, india *corresponding author: sushilsolanki@spa.ac.in https://doi.org/10.5755/j01.sace.32.1.30374 journal of sustainable architecture and civil engineering vol. 1 / no. 32 / 2023 pp. 172-185 doi 10.5755/j01.sace.32.1.30374 abstract introduction a large number of existing building stock in india was built before the implementation of government guidelines mandating the green building codes. these buildings have been operating with various inefficiencies pertaining to their resource consumption and emissions. literature suggests that the option of functional retrofitting of building has a potential to reduce this inefficiency by up to 50%. this paper investigates this potential by analysing actual cases of functional retrofitting of buildings (for achieving greater operational efficiency) in indian context. the environmental impact analysis in this study includes the impact categories of primary energy demand, global warming potential, abiotic depletion potential, ozone depletion potential and water resource consumption for both pre-retrofit and post-retrofit scenario of building. the results are then correlated to the initial cost of functional retrofitting for each case in order to identify the inter-relationship and trend with respect to the level of intervention opted for the cases. keywords: functional retrofitting, operational efficiency, environmental impact. there is an understanding that the environmental impact of new construction is more than an alternative of retrofitting (rodríguez, et al., 2017) (power, 2008) however, there can be various configurations of building retrofitting (structural as well as functional), the environmental impact and cost implications of which can be studied and analysed in-depth for indian context, a) to identify their variation across various retrofitting configurations for a building and, b) to understand the relationships of various environmental factors and parameters for decision-making. the growing population and increase in the demand of infrastructure, housing and other buildings has resulted in enhanced construction activities, and caused a shortage of conventional building materials, and increase in the quantity of wastes and pollution levels. to ensure sustainable growth, urban areas and buildings need to provide environment-friendly, innovative, and productive techniques to ensure better quality of living. (rastogi & paul, 2020) buildings and construction projects are planned and developed to deliver the expectations of not only professionals, clients and stakeholders, but also the users of the buildings and the community. in addition to the fulfilment of structural and functional qualities, the buildings support daily user activities, and also need to ensure that they fulfil the environmental performance. it has been observed that retrofitting can significantly help an existing structure to improve its environmental performance efficiency. (seshadhri & paul, 2017). 173 journal of sustainable architecture and civil engineering 2023/1/32 according to a report published by teri in 2019, there is a need for building retrofitting as a large number of existing building stock of india was built before the green building market in india had access to advanced and efficient energy saving technologies and mandating compliance to green building code. majority of the buildings within the typologies of commercial office spaces, healthcare infrastructure and hospitality, were planned without major attention to climate responsive passive design strategies and environment friendly active systems (teri 2019). this leads to an inefficient functioning of these buildings throughout their service life (60 years) causing monetary losses (which are unnecessary and avoidable) to the organizations. these inefficiencies in energy consumption can be reduced through retrofitting measures by up to 50%. (khosla & janda, 2019) such inefficiencies and inadequacies of construction projects and buildings, and the growing need for enhanced quality and environmental performance of the buildings provides opportunities for the enhancement of research and development of new, strengthened and augmented systems, with appropriate processes and methodologies and processes. (paul & seth, 2017). these value-adding aspects can prove to be highly beneficial when considered to expedite the construction and retrofitting processes, and can further act as catalysts of growth in economic activities and help in the improvement of social indicators of the nation. (mittal, paul, & sawhney, 2019) and the fact that green building market share of retrofit measures is expected to rise to approximately 25-40% in the next decade (green building retrofit and renovation, 2009) (word green building trends, 2018) suggests that, there is a great potential for optimizing the operational efficiency of these building typologies by adopting various strategies of energy-retrofitting. even as standardization of designs, planning, methodologies and processes can aid in maximizing the value and benefit from an existing or new building, peculiarities of projects, site, environmental requirements can compel the project managers, architects and other professionals to improvise, modify and apply in different processes and needs of retrofitting in different buildings. (paul, khursheed, & singh, 2017) it will also be useful for stakeholders, decision makers and project managers and decision makers to rearrange and prioritize their maintenance and management processes in accordance with importance, availability of funds, etc. (seshadhri & paul, 2018). existing literature pertaining to retrofitting compares and analyses specific components for building retrofitting with respect to cost and environmental impact parameters. however, there is a lack of a comprehensive study of the impact of different layers of retrofitting configurations (equipment, service systems, envelope and deep retrofitting) of buildings. (bostenaru, 2004) (konstantinou & knaack, 2011) (el-darwish & gomaa, 2017) (jafari, 2018). various international literatures discuss the economic implications and environmental impact of building energy retrofitting of detached and semi-detached row houses, and other residential establishments (vrijders & delem, 2009) (jafari, 2018) however, results of these literatures are in various international contexts and only explore the system retrofit options pertaining to building heat demands. the literature suggests that additional results may be obtained by analysing other retrofit case scenarios. various literature indicates that there is a gap with respect to the assessment of environmental impact through life cycle energy analysis (including embodied energy, operational energy and demolition energy) of building retrofitting cases in indian context (power, 2008) (rodríguez, et al., 2017) (rawat, divahar, & kulshrestha, 2019) it also suggests a lack of an in-depth understanding of inter-relationship of cost, environmental impact and operational efficiency with the level of retrofitting intervention done for a building in indian context. inefficiencies in supervision and assessment of the processes and materials used can lead to delays in retrofitting and construction processes. this may, in turn, impact project performance severely, leading to cost overruns, disputes, arbitration and even abandonment of the project. (mittal, paul, rostami, riley, & sawhney, 2020). journal of sustainable architecture and civil engineering 2023/1/32 174 hence, this research focuses on analysing the environmental impact of energy efficient functional retrofit measures for buildings in indian context. the research will also attempt to identify the relationship between various decision parameters including, level of intervention, achieved operational efficiency, environmental impact and incurred costs. retrofitting of buildings retrofitting is a process of adding or providing something with a feature or a component which was not a part of it during its initial manufacturing or construction. in building construction paradigm, retrofitting can be defined as adding or providing an existing building with features or components to which were not the part of its original structure or building plan, when it was constructed. these new features or components can range from replacement of existing equipment of a building to strengthening of the entire building structure. in the context of built environment, it is described as substantial physical change (as compared to the existing building details) at building level. it is also used interchangeably with terms such as, ‘refurbishment’, ‘conversion’ or ‘refit’. a building once constructed will continue to serve its purpose for a long period termed as the service life of a building (which can be 50-70 years). however, a building continuously deteriorates because of environmental wear and tear during its entire service life. this eventually results in weakening the building structure and renders it unsafe or not fit for public use. it is this stage, when the building is said to have reached its end-of-life phase. this situation might also arise because of a recent disaster (fire, earthquake, flood, etc.) and can make the building unfit for use well before its anticipated service life. in such scenarios, structural strengthening of such a building through retrofitting can be an option to prolong its service life and continue its usage. deterioration of a building structure is not the only reason for retrofitting. current paradigm of sustainability and sustainable built environment demands the reduction of greenhouse gas emission, improving energy and resource consumption and reducing the overall environmental impact (as directed by the sdgs of un). this resulted in development of a new typology of building retrofitting which is focussed in achieving energy efficiency and reduce environmental impact of the existing building stock of the cities, termed as building energy retrofits. this includes the replacement of existing equipment and service systems of building with energy efficient alternatives, improving the indoor environment quality for better physical and psychological comfort through changes in envelope, lighting, building material, etc. similarly, there can be various other reasons for retrofitting an existing building; however, the underlying purpose is to make the building fit for its existing or redefined use as well as enhance it. in order to achieve this purpose, a whole building retrofitting activity can be broadly divided into structural (strengthening the building structure) and functional (replacement and addition of building service systems) retrofitting. these broad categories can be further sub-divided on the basis of measures taken for retrofitting or the reason for which the building is retrofitted. functional retrofitting this category of retrofitting focuses on the replacement and modifications of building systems for its redefined use or enhancement of operational efficiency of the building. the measures of functional retrofitting of buildings can be broadly divided into equipment, service systems, building envelope and deep retrofitting, which is the optimized combination of other three measures. there are specific challenges associated to the analysis, design and execution of these retrofitting measures and can be an influencing factor for their selection. functional retrofitting of a building might or might not be carried out along with structural retrofitting of an existing building and completely depends upon the requirements of building and its stakeholders. 175 journal of sustainable architecture and civil engineering 2023/1/32 the approaches of functional retrofitting of can be broadly divided into four categories, equipment retrofitting, service system retrofitting, building envelope retrofitting and deep retrofitting, which will be discussed in detail in this section of the report. these approaches can be implemented for a retrofitting project in isolation or in combination with other approaches to achieve and optimized solution. selection of this combined optimized retrofit solution is based on various social, economic and environmental factors which are guided by the goals and need of the project itself. equipment retrofitting an equipment retrofit involves replacement and modification of existing service equipment or fixtures/appliances of an existing building such as, chiller, boiler, ac units (split, fcus, ahus, etc.), light fixtures, electrical fixtures, appliances, etc. this level of retrofit aims at reducing the energy consumption of the building as a whole by use of energy efficient (star rated) fixtures and equipment. the upgrades of fixtures and equipment pertaining to the plumbing and sanitation system help in efficient consumption of water and reduce waste generated by the building. these measures result in reduction in environmental degradation because of building operation. service system retrofitting a service system retrofit aims at achieving higher efficiency of building services by improving the design, typology and components of those services. this includes improvement and replacement of distribution system of various services of the building such as, hvac, plumbing, electrical layouts, etc. these upgrades are focussed on designing the systems for future use of the building, which result in reduction of the resource consumption of the entire building. for example, upgrades of the hvac system in hospitals might involve the usage of variable refrigerant volume (vrv) systems and a flexible chilled water distribution to cater to variable requirements of different building zones. these new systems might be coupled with an integrated building management systems (bms) for their effective monitoring and control to continuously improve the resource consumption efficiency of whole building. bms uses an automated computer-based control system which monitors a buildings ventilation, lighting, power systems, disaster response systems, fire systems and security systems, on predefined parameters, benchmarks and tolerances. building envelope retrofitting building envelope retrofit focusses on improving the indoor environment quality (ieq) of a building. ieq of a building includes factors such as, ambient temperature, relative humidity levels, wind speed, light intensity levels (lux), noise levels, etc. which are under the larger umbrella of thermal, visual and auditory comfort of building occupants. this typology of retrofitting modifies or replaces the existing exterior walls of the building with materials (of the wall section) which have better performance than existing features with respect to its thermal insulation (transmittance, u-value), sound insulation, surface reflective index, etc. deep retrofitting der, or deep energy retrofit, can be understood as an energy conservation measure used in existing structures, which also serves the purpose of overall improvement of the performance of the building. a deep energy retrofit can also be defined as a construction process and whole-building analysis, the aim of which is to achieve minimisation of on-site energy use in a structure by 50% or more, in comparison to the baseline energy use (this uses utility bills analysis for calculation). the process makes use of existing materials, technologies and construction practices. this type of retrofitting process helps to achieve multi-fold benefits that extend beyond energy cost savings, as compared to conventional energy retrofits. the process can also involve approaches of functional retrofitting of buildings journal of sustainable architecture and civil engineering 2023/1/32 176 remodelling of the building in order to achieve synchronisation in indoor air quality, energy, thermal comfort and durability. conventional energy retrofits typically emphasise on isolated system upgrades (i.e. hvac equipment and lighting). while these retrofits have been observed to be fast and simple, they may often miss the opportunity to save more energy in a cost-effective manner. both conventional and deep energy retrofits follow different approaches and methodologies, and lead to different outcomes. 1 pre-planning stage 1.1 establish performance baselines (inspection, energy audit, energy baseline) 1.2 develop project goals and performance metrics (annual energy target or reduction goal, establish non-energy goals) 2 planning stage 2.1 analysis of probable retrofit solutions 2.2 design of the best valued retrofit solution (based on cost-benefit ratio or payback period and aligned with the objectives and goals) 2.3 planning of the construction phase (schedule and cost baseline, procurement plan, monitoring and control plans) 3 construction stage 3.1 procurement as per the plan (execution agencies, service components, materials, etc.) 3.2 monitoring and control of the construction 4 test out and inspection stage 4.1 testing and commissioning of installed components 4.2 verification of installation and performance of retrofit measures 5 post-occupancy stage 5.1 behavioral adjustments and short-term targets for users/occupants 5.3 performance feedbacks table 1 project processes of functional retrofitting of buildings a building affects the environment throughout its life, right from the construction (pre-use phase) to building operation (use phase) and eventually the end-of life phase. during pre-use phase the construction activities generate a significant amount of solid waste, embodied energy associated to building material is added and subsequent ghg emissions take place. during the operational phase, a building consumes energy and various resources to function effectively and cater to user requirements which also results in ghg emissions. the repair and maintenance activities during operational phase results in recurring embodied energy and the subsequent ghg emissions take place. eventually, during the eol phase of building, demolition waste is generated which requires energy for transportation and processing. however, the environmental impact of buildings includes various other categories and parameters apart from the energy consumption and ghg emissions which are discussed below. environmental impact 177 journal of sustainable architecture and civil engineering 2023/1/32 impact category impact parameters energy consumption (abiotic depletion potential) life cycle energy demand, cumulative energy demand global warming potential life cycle ghg emissions (co2, co, ch4 in gaseous state) acidification potential emission of so2, nox, hcl (in gaseous state) eutrophication potential emission of nox (gaseous) and po4, nh3 (aqueous) ozone depletion potential emissions of chlorofluorocarbons and hydrochlorofluorocarbons water consumption resource depletion abiotic depletion potential (adp) this includes the depletion of natural non-renewable resources of the planet in the terms of oil, gas and coal reserves. 𝐸𝐸𝐸𝐸! = $ 𝐵𝐵𝐵𝐵" 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒!," $ "%! 𝐸𝐸𝐸𝐸& = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒&,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸' = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒',".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸( = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒(,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸) = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒),".𝐵𝐵𝐵𝐵" $ "%! bk = quantity of resource utilized per functional unit; ec1,k = total world reserves of that resource global warming potential (gwp) it is calculated as a sum of ghg emissions multiplied by their respective gwp factors. 𝐸𝐸𝐸𝐸! = $ 𝐵𝐵𝐵𝐵" 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒!," $ "%! 𝐸𝐸𝐸𝐸& = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒&,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸' = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒',".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸( = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒(,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸) = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒),".𝐵𝐵𝐵𝐵" $ "%! bk = emission of ghg ‘k’; ec2,k = gwp factor relative to co2 acidification potential (ap) it is based on contributions of so2, nox, hcl, nh3 and hf to potential formation of h+ ions. 𝐸𝐸𝐸𝐸! = $ 𝐵𝐵𝐵𝐵" 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒!," $ "%! 𝐸𝐸𝐸𝐸& = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒&,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸' = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒',".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸( = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒(,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸) = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒),".𝐵𝐵𝐵𝐵" $ "%! bk = emission in kg per functional unit of gas ‘k’; ec4,k = ap factor relative to so2 eutrophication potential (ep) it is defined as potential of a product or process to cause over-fertilization of a land or water resource. 𝐸𝐸𝐸𝐸! = $ 𝐵𝐵𝐵𝐵" 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒!," $ "%! 𝐸𝐸𝐸𝐸& = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒&,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸' = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒',".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸( = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒(,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸) = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒),".𝐵𝐵𝐵𝐵" $ "%! bk = emission of nitrogen and phosphorous based species ‘k’; ec5,k = ep factor relative to po4 2ozone depletion potential (odp) this indicates the potential of emissions of cfcs and hcs which deplete the ozone layer of atmosphere. 𝐸𝐸𝐸𝐸! = $ 𝐵𝐵𝐵𝐵" 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒!," $ "%! 𝐸𝐸𝐸𝐸& = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒&,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸' = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒',".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸( = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒(,".𝐵𝐵𝐵𝐵" $ "%! 𝐸𝐸𝐸𝐸) = $𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒),".𝐵𝐵𝐵𝐵" $ "%! bk = emission ozone depleting gas ‘k’; ec3,k = odp factor relative to cfc-11 table 2 environmental impact categories table 3 definitions and formulas environmental impact categories / parameters following are the indicators for various categories of environmental impact for a building during its construction, operation and demolition phases. the below stated parameters can be assessed by breaking down all the processes into sub-processes and various products used within those processes for the construction (or retrofitting) of a building. the inputs and outputs within these sub-processes help in quantitative assessment of the various impact parameters and analyse the overall environmental impact potential of a building. systematic approach for such an assessment is the life cycle assessment (lca) approach as defined by the iso 14040 for environmental impact analysis. journal of sustainable architecture and civil engineering 2023/1/32 178 fig. 1 system boundary of lca study (source iso 14040) fig. 2 life cycle energy of a building (cabeza et al. 2014) adopted framework for environmental impact analysis the approach of life cycle energy analysis (lcea) is adopted to assess the primary energy demand (in gj) and adp of the buildings for post retrofit scenario. this approach is based on the general principles of lca as outlined in iso 14040 and is used to quantify the effects of a product or process on the environment during the different stages of its life cycle. life cycle energy of the building is the sum of the all the energies incurred in its life cycle as evident from the above diagram (fig. 2). it is thus expressed as: lce = eei + eer + oe + de. where, lce = life cycle energy, eei = initial embodied energy, eer = recurring embodied energy, oe = operational energy, de = demolition energy (demolition + transportation + disposal). environmental impact analysis of functional retrofit cases 179 journal of sustainable architecture and civil engineering 2023/1/32 a similar approach was adopted for analysing the ghg emissions to determine the global warming potential of the buildings for post-retrofit scenario. this includes the assessment of emissions during; a) construction phase (embodied carbon calculations) which involves the emissions associated to demolition process (demolition activities and waste disposal) & construction activities, transportation of demolition waste (away from site), and emissions associated to consumed materials; b) operation phase which involves emissions because of fuel usage of building by assessing energy consumption of building using simulation software, and recurring embodied carbon because of maintenance and repair activities of building; c) end of life phase of building which involves emissions associated with demolition process (demolition, transportation & waste disposal). hence, ghg emissions were calculated for the entire life cycle of building. the ozone depletion potential of buildings is calculated with respect to the refrigerant charge of hvac systems (centralised ac systems as well as the unitary systems) and also includes the additional refrigerant required because of 2% leakage per year. water resource consumption was calculated in kl/year for the building which included the domestic and flushing water demand, irrigation water demand, and cooling tower make-up water demand. the life cycle calculations for above environment impact categories were done with an assumption that the buildings will continue to operate for the next 50 years. this calculation is done for both preand post-retrofit scenario of considered cases to assess the change in environmental impact. and this calculation does not include the structural strengthening or structural retrofit that the building might require in order to extend its service life. details of functional retrofit cases basis of selection of cases building retrofit cases having major interventions in three different levels of retrofit interventions (building envelope, equipment & service systems & deep retrofitting) were considered. cases with a primary goal of improving energy efficiency or transforming the building into an environment friendly building were considered. table 4 functional retrofit cases table 5 functional retrofit case project details sr. no. typology year of completion retrofitting type case-1 private office headquarters (mumbai) 2009 deep retrofitting (hvac [equipment and distribution system], lighting equipment, support systems, envelope changes, interior layout change) case-2 private office headquarters (mumbai) 2013 equipment | service system | building envelope (hvac [equipment and distribution system], lighting equipment, support systems, envelope enhancements) case-3 office space for lease (delhi) ongoing equipment | service system | building envelope (hvac [equipment], lighting, envelope (façade) replacement) case-1 case-2 case-3 age of building 82 years (1939) 49 years (1972) 21 years (2000) retrofitting of building initiated – 2009 completed – 2010 completed – 2010 initiated – 2019 ongoing project location churchgate, mumbai, maharashtra churchgate, mumbai, maharashtra new friends colony, delhi climate zone warm and humid warm and humid composite total built-up area 10,250 sqm 3,826 sqm 7840 sqm number of floors 1 part basement + ground + 6 storey | height – 23m 2 basements + ground + 6 storey | height – 19m 2 basements + ground + 9 storey | height – 35m cost of retrofitting 24.75 crore inr 24150 inr/sqm 5.82 crore inr 18476 inr/sqm 6.5 crore inr 8300 inr/sqm occupancy 450 people 100 people 375 people journal of sustainable architecture and civil engineering 2023/1/32 180 retrofitting configuration of case-1 consists of, the building envelope changes involving replacement and redesign of external fenestrations to doubly glazed aluminium frame windows with enlarged size, and changes in the central shaft of the building which was converted to an atrium. there were changes in the hvac system including replacement of water-cooled chiller to aircooled chillers, and change in the hvac layout including ducts, shafts and equipment. there were major changes in the internal layout of the building in order to enhance daylight penetration within the building. there were minor changes in the mep systems of building, with energy efficient fixtures replacing the conventional fixtures (lighting and plumbing). the overall environmental impact benefit received because of implementation of these retrofit measures is shown in table 6. environmental impact analysis of considered retrofit cases table 6 environmental impact analysis for case-1 environmental impact category pre-retrofit scenario post-retrofit scenario benefit primary energy demand(gj) 1,71,575.29 1,41,839.28 – 29,736.01 (21.13%) abiotic depletion potential coal 7.28e-10 5.48e-10 overall reduction of 24.67%oil 9.35e-10 7.05e-10 gas 4.60e-09 3.46e-09 ghg emissions (gwp) (mt of co2eq) 21,352.64 16,441.65 – 4,910.99 (23.00%) ozone depletion potential (w.r.t. cfc-11) 40.10 0.00 – 40.10 (100%) water consumption (litres per year) 81,11,876 30,94,608 – 50,17,268 (61.85%) environmental impact category pre-retrofit scenario post-retrofit scenario benefit primary energy demand (gj) 92,830.47 78,916.31 -13,914.16 (14.99%) abiotic depletion potential coal 4.00e-10 3.34e-10 overall reduction of 16.5%oil 5.14e-10 4.29e-10 gas 2.53e-09 2.11e-09 ghg emissions (gwp) (mt of co2eq) 11,638.76 9,777.74 -1,861.02 (15.99%) ozone depletion potential (w.r.t. cfc-11) 17.82 0.00 -17.82 (100%) water consumption (litres per year) 38,23,024 36,02,150 -2,20,874 (5.78%) table 7 environmental impact analysis for case-2 retrofitting configuration of case-2 consists of, the hvac system changes in which the water-cooled chillers were replaced by more efficient chillers with high cop. the hvac distribution is modified by using ahus for each floor as opposed to the original system which consisted of 2 ahus for entire building. there were minor changes in building envelope involving replacement of single glazed windows with double glazed windows for the building. the overall environmental impact benefit received because of implementation of these retrofit measures is shown in table 7. retrofitting configuration of case-3 consists of major changes in building envelope involving replacement of single glazed structural glazing with double glazed structural glazing for the building. the overall environmental impact benefit received because of implementation of these retrofit measures is shown in table 8. 181 journal of sustainable architecture and civil engineering 2023/1/32 environmental impact category pre-retrofit scenario post-retrofit scenario benefit primary energy demand (gj) 1,37,110.49 1,19,776.47 -17,334.02 (12.64%) abiotic depletion potential coal 7.35e-10 6.32e-10 overall reduction of 13.92%oil 9.44e-10 8.13e-10 gas 4.64e-09 4.00e-09 ghg emissions (gwp) (mt of co2eq) 21,160.22 18,306.22 -2,854.00 (13.49%) ozone depletion potential (w.r.t. cfc-11) 35.64 0.00 -35.64 (100%) water consumption (litres per year) 67,92,524 65,53,063 -2,39,461 (3.52%) table 8 environmental impact analysis for case-3 primary energy demand | global warming potential (gwp) in case-1, the substantial changes were observed in building envelope, hvac equipment and distribution as well as the lighting system (in relation to the changes in internal layout of building) resulted in a reduction of energy consumption and gwp during the operational phase of building. recurring embodied energy and embodied carbon for post retrofit configuration of building is significantly lower than the original configuration. this results in reduction of primary energy demand and gwp of building. in case-2, the substantial changes included, building envelope, hvac equipment and distribution. these resulted in an overall reduction of primary energy demand and gwp of building, however, not as significant as in case-1. similarly in case-3, the substantial changes were seen in building envelope. this results in lower benefits (lowest among the three cases) for the post retrofit scenario of building. abiotic depletion potential (adp) adp only included the resource consumption (coal, oil and gas) during the operational phase of building for post retrofit scenario and is directly related to the energy consumption of building. the graph above shows the average reduction in consumption of resources and follows a similar trend as the primary energy demand and gwp with highest reduction being achieved in the case-1 and lowest being achieved in case-2. ozone depletion potential (odp) the odp is dependent upon type of refrigerant used and its total replacements during operational phase of building. for all the three cases, old hvac equipment was replaced. this resulted in a change of refrigerant from r-22 to r134a, in which the latter has ‘0 odp’. hence, this resulted in a reduction of 100% for all the three cases for their post retrofit scenarios. water consumption in case-1, the water consumption reduction is maximum because of the change in cooling tower make-up water demand. as the new hvac system consists of an air-cooled chiller for the building as opposed to the water-cooled chiller for pre-retrofit phase of building. this removed the component of ‘make-up water’ for post retrofit scenario of building, thereby reducing the total water consumption. however, in case-2 and case-3, there was no significant reduction in total water demand and the slight reduction which can be observed from the graph above is because of reduction in the cooling tower operation time for post retrofit scenario. results and discussions journal of sustainable architecture and civil engineering 2023/1/32 182 overall variation in environmental impact hence, highest environmental benefits (21-25%) were observed for case-1 with deep retrofitting involving changes in internal layout of building, the external envelope, equipment of service systems and distribution. environmental benefits (15-16%) for case-2 with service systems and building envelope retrofitting, are significantly lower as compared to case-1. least benefits (1214%) were observed for case-3 with building envelope retrofitting), which is not a significant decrease as compared to case-2. the energy performance index (epi) reduces by 25% for case-1 (to 66.97 kwh/ sqm/year), 16% for case-2 (to 109.34 kwh/sqm/year), and 14% for case-3 (to 83 kwh/sqm/year). fig. 3 environmental impact variation across all cases as per the analysis of considered cases, functional retrofitting of building for energy efficiency provides significant benefits of up to 25% for the deep retrofitting case with respect to environmental impact reduction and resource consumption reduction. substantial component of these benefits is associated with the operational phase of the building which is a direct result of implementing energy efficient retrofits in considered cases. it was also observed that the environmental impact reduction (with respect to ped, adp and gwp) increases with the increase in level of intervention for building retrofitting. this study explores the potential of environmental impact reduction of building through implementation of functional energy retrofit measures in buildings in indian context. large number of existing building stock in india will require retrofitting interventions in the next couple of decades. and the retrofitting measures for energy efficiency in buildings will prove to be significantly beneficial for reducing the environmental impact of the old buildings. this study helps in developing an understanding of the achieved environmental impact reduction and operational efficiency with the incurred initial costs for implementing the energy efficiency functional retrofitting measures in buildings, and prove to be beneficial in decision making process. conclusion 183 journal of sustainable architecture and civil engineering 2023/1/32 future scope of the study results in this study cannot be generalized to all retrofitting cases as they are based on three considered cases. hence, similar analysis can be conducted for more cases of building retrofitting in india in order to generalize the result for each climatic zone in india. results in this study can be validated by studying other examples of functional retrofitting of buildings for energy efficiency and relating it to the inter-relationship graph obtained in this study. fig. 4 interrelationship graph between environmental impact reduction and incurred cost referencesbostenaru, d. m. 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engineering 77. united nations environment programme, ed. 2011. towards a green economy: pathways to sustainable development and poverty eradication. nairobi, kenya: unep. x.w. zou, patrick, rodney stewart, morshed alam, edoardo bertone, and oz sahin. 2016. “retrofitting public buildings for energy and water efficiency.” 1. sbenrc project 1.43. australia: sustainable built environment national research centre. https://sbenrc.com.au/ app/uploads/2015/11/sbenrcp1.43_progressreport1may2016_retrofitguidelines_forweb.pdf. about the authors risabh rastogi architect savills property services (india) private limited main research area building retrofitting address savills property services (india) private limited, futura, magarpatta road, 411 028, india e-mail: rishabh.rastogi123@gmail.com sushil kumar solanki associate professor lecturer school of planning and architecture, new delhi main research area building rehabilitation and retrofitting address indraprastah estate, ito, new delhi, india tel.: +91-8823098230 e-mail: sushilsolanki@spa.ac.in this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 3 darnioji architektūra ir statyba 2014. no. 2(7) journal of sustainable architecture and civil engineering issn 2029–9990 architecture as a second nature amal wasfi amcordic design and consulting, 1108-3740 albert street, burnaby, bc, canada. *corresponding author: amal@amcordic.com http://dx.doi.org/10.5755/j01.sace.7.2.5981 the paper suggests a new sustainable approach of building design. this approach makes architecture welded into nature. it functions in the same way as ecologies. the functional concepts in the fields of biology and ecology are used to suggest the techniques to create a new architecture. mimicking the organism systems and processes in nature using new cybernetic technology are the new techniques for “biointeractive buildings”. the resulting “modern ecologies” based on a “second nature” unify the natural and the artificial into one entity. this ecology would be a continual dynamic relationship between matter, energy, and information in a specific medium (environment). it would be hard to separate what is life and what is matter. these smart buildings, in some ways, would “come alive”. keywords: ecological approach, biomimicry , sustainable architecture, passive architecture, interactive architecture. 1. introduction environmentalism has come a long way since its inception in the era of the industrial revolution. mainly, there were two types of environmental movements in the west: the naturalists or preservationists who are concerned with the preservation of species of plant and animal life and the conservationists who are concerned with the efficient utilization of natural resources. the aim of the conservationists is the proper use of nature in the interest of the humankind; whereas the preservationists sought the protection of nature from humans and they advocate the idea of separating wilderness areas from civilized areas (naess,1999). the common thread running through the conservationist’s perspectives is their focus on intelligent and informed management of the environment to fit man. they feel relatively free to trade-off environmental quality for economic benefit (glow, 1992). their viewpoints embody the western faith in the mastery of nature: as nature is something to exploit in a way that should last as long as possible. on the other side, the preservationists believe in the importance of ecological species but they consider human species separate and harmful to nature. according to the preservationists, the human should physically be separated from what they call “wilderness”. in this paper a new approach towards the relation between human and nature is suggested. the new approach should emerge with an explicit rejection of the idea of man’s supposed separation from and possibly domination over nature. this new perspective should come from the ecological trend that considers man as one of the species in the ecosphere, part of and dependant on the rest of nature. and the goal is to focus on how to live in harmony with the rest of the other species and live in peace with nature. this perspective promotes a more radical analysis of the industrial society itself. the current trend of using technology is to go against nature to control it. if the philosophy of this industrial society is responsible for a general disruption of the ecosphere, which is detrimental, then the problem is more than inefficient practices of exploiting nature. the problem lies in the deep relation between man and nature. human should see themselves as part of nature. every technological invention and innovation should be inspired and work in harmony with nature not against it. similar to the way that all the systems in our body work in harmony, any invented system should be part of the whole nature. that philosophy will make a substantial difference in resolving environmental problems. 2. how can we imply this perspective to our buildings? 2.1. goals for a new design the suggested new ecological approach should lead to a new architectural model to rebuild the relation between architecture and nature. starting with a historical view, i’ll show how architecture evolved independent of nature since the industrial revolution. lately, however the relation between architecture and nature started to rebuild itself. truly interested in this above mentioned transition, i will attempt to discuss the potential and critical path from the past to the present. the scientific revolution made a crucial change on the whole way of approaching the world. architecture which usually reflects the philosophy of its period faced a 4 major change. after the modern revolution the classic way of ornament (which was part of the classic architecture theme) was considered an arbitrary beauty (freigang and kremeier, 2003). c. perrault in the seventeenth century distinguished between the arbitrary beauty and the positive beauty. he argued that positive beauty comprised three factors: richness of material, precision of execution and symmetry. c. perrault meant rational, geometric, largely orthogonal order. his universal beauty became the basis for neoclassic, which we now see to have been the ultimate origin of a technologically rational, gridded architecture. in 1908 a. loos published his famous essay “ornament and crime” in which he wrote: “modern ornament has no forbears and no descendant, no past and no future, it is joyfully welcomed by uncultivated people to whom the true greatness of our time is a closed book and is after a short time rejected.” this stricture against the invention of ornament went to the degree they considered ornament is a crime (gans and kuz, 2003). in 1924 l. sullivan published his book “a system of architectural ornament according to the philosophy of man power”. in his book he advocates the idea of geometrical figures. design became a tool to redesign the whole society to be more materialist and to express the triumph of the man upon nature. the shape of the building should follow the functions inside the building and no other meaning should be embedded “the form is inherent in the specific task” (sullivan,1967). in the sixties of the 20th century a new argument started to take place about the cultural dimension. the architecture of our cities should search for a meaning and nothing exists in isolation. to summarize this emerging movement as hegel sees it: “symbolic art seeks the perfect unity of form and content that classic art finds and romantic art transcends” (ameriks, 2002). the social crisis of industrialization leads to new investigations searching for a holistic cultural vision. building as a part of the context, (the place and the time), became part of the design principles for the post-modern architecture. 2.2. strategies context. our main strategy is to change the meaning of context and how to deal with context. the traditional meaning of context. post-modern architecture started to reflect the spirit of the place, which is represented by the surrounding buildings, and the spirit of the time. architecture, from the sixties of the last century, sought to work as part of the city style. it worked in harmony with the urban context. the meaning of the context was limited to the human achievements and cultural values. the broader world with its nature was neglected. the built environment was the focus and the human needs were the aim. that was the basic assumption for the meaning of context. the environmental crisis lately forced people to rethink this trend. the suggested new meaning of context. a need for new attitudes towards “nature/earth” became urgent. new visions started to emerge concerning our relation with nature. a new way of viewing and valuing nature started to develop. the earth is a super-natural place that embraces many life-forms living harmoniously. architecture which represents the man made environment should respond to its natural milieu, implying “appropriateness” and “harmony” within the larger context. better to build systems connecting the outside natural world with the inner life by making the inner part of the outside. by this we exceed the traditional meaning of the city as context for our new buildings by another meaning for context which is the entire natural world around. we replace the goal to satisfy the human needs by a larger goal to satisfy all the natural species on earth. this is a new holistic approach with a new assumption. nature as a guide. design should be approached as a way of risk taking instead of reducing the risk. “our ideas we have had and evaluation we have made are free for recycling” (gans and kuz, 2003). let us be opened to make a total change to our prevailing concepts. we should create a balanced world where the built environment works in total harmony with nature. instead of superimposing form, the architect’s responsibility would be to let the form unify with the whole context. in order to reach that, the new system should work similar to the natural world not alien from it. it is better to start with conceiving, then transforming, the natural systems with its complicated processes. from that we can move to initiate new architecture. this new “digestive building system” would function to support the ecosystem. this way we are exceeding the traditional green building practices and similar efforts. the goal of traditional green practices is to look for less harm that is done by an alien, juxtaposed system, while our goal is to create buildings that function like nature. this natural philosophy conceives of the universe as an organism and the work of architecture as an organic operation. the organic approach here is a mode rather than a model, as a program rather than a form. forming here is a dynamic process. in this dynamic process of forming the “architectural form”, we create a best and stable relation between built and natural environment. this new architecture is welded into nature and the whole is a single body animated by a single spirit. architecture is a form that includes the pattern of human behaviour, which is natural and can work in unity with the rest of nature. in this context there is continuity between object (architecture), environment and behaviour. we can call this architecture a “second nature”. flowing from this “second nature”, a new design approach termed bio-mimicry has a highly promising design mechanism. 2.3. design techniques biomimicry. biomimicry is the imitation of the models, systems, and elements of nature for the purpose of solving complex human problems (from bios, meaning life, and mimesis, meaning to imitate) is a design discipline that seeks sustainable solutions by emulating nature’s timetested patterns and strategies, e.g., a solar cell inspired by a leaf (biomimetics..., 2014). the term organic, first appears as dynamic rather than static concept of nature in artistic and scientific terms. and what distinguishes organism is the 5 evolving, developing processes.”the gestalt of an organism accounts for the complexity of its life cycle as it gradually develops yet somehow retains its identity” (gans and kuz, 2003). according to the oxford dictionary, the term “organism” is directly related to the term “organization”. there is a long tradition of defining organism as a selforganizing being. in multi cellular term, “organism” describes the whole hierarchical assemblage of systems. in biomimicry, we look at nature as model, mentor, and measure (evans, 2014): model: biomimicry is a new science that studies nature’s models and then emulates these forms, processes, systems, and strategies to solve human problems – sustainably. mentor: biomimicry is a new way of viewing and valuing nature. it introduces an era based not on what we can extract from the natural world, but what we can learn from it. measure: biomimicry uses an ecological standard to judge the sustainability of our innovations. after 3.8 billion years of evolution, nature has learned what works and what lasts. the bio-mimicry “helix” will be introduced here as a continuous model illustrating two integral products of the bio-mimicry process organs and organisms (benyus, 2011). this metaphorical approach to the definition embellished the primary goal of bio-mimicry – to visualize man-made systems and products as natural processes. the concept of biomimicry is often oversimplified into a linear process to create a design emulating the observation or the shape only. bio-mimitics is also typically mistaken for biotechnology as it does not exploit “bio-assisted” processes such as using green algae to treat waste water. according to e. royall (2010), as natural systems evolving continuously to meet dynamic changes, biomimicry is considered to be a spiralling, continuous process, taking nature as inspiration to generate “organs” (individual products) or “organisms” (systems and processes) for the purpose of integration into a sustainable system. the “helix” model of biomimicry reflects a number nuances. primarily the model is spiral. this represents the idea of biomimicry as a continuously evolving process, infinitely seeking a closer fit to the fluctuating environment. this model reflects continuous feedback and repeated fine-tuning required to adapt “organs” and “organisms” to the environment. organs include singular products like photovoltaic cells or fibber optics, while organisms are systems such as smart grid or cities (royall, 2010). biomimicry differs from other “bio-approaches” by consulting organisms and ecosystems and applying the underlying design principles to our innovations. this approach introduces an entirely new realm for entrepreneurship that can contribute not only innovative designs and solutions to our problems but also to awakening people to the importance of conserving the biodiversity on earth that has so much yet to teach us. a sincere search effort for principles from this forming model should make moot the distinctions between organic and inorganic. this technique leads to a harmonious environment. others think that the larger medium – ecology – can lead to better environmental solutions. design ecologies. recently new terms entered the field of architecture to describe the ability of the new architecture to meet changing needs with respect to evolving environmental demands. some of these practices called responsive architecture which describe the new buildings that measure actual environmental conditions (via sensors) to enable these buildings to adapt their form, shape, color or character responsively via actuators (wigginton and harris, 2002). responsive architectures distinguish themselves from other forms of interactive design by incorporating intelligent and responsive technologies into the core elements of a building’s fabric. for example: by incorporating responsive technologies into the structural systems of buildings, architects have the ability to tie the shape of a building directly to its environment (responsive..., 2014). other practices and research went step further to what they call interactive architecture. interactive architecture signifies a field of architecture in which objects and space have the ability to meet changing needs with respect to evolving individual, social, and environmental demands. the convergence of embedded computation and kinetics in architectural form with the intention to involve human and environmental responses creates an architecture that could be termed interactive or responsive, but can also be cybernetic. such systems must utilize a definition of interaction as circular, or they are merely “reacting” and not “interacting”. according to l. bilung (2000), reactive systems are unlike the transformational systems: “unlike transformational systems which operate on inputs available at the beginning, reactive and interactive systems maintain an ongoing series of interactions”. reactive systems follow a pace dictated by the environment. the environment determines when the systems must react and provides inputs. the systems respond to the inputs by possibly sending outputs to the environment (bilung, 2000). the new concept in interactive architecture – cybernetics – is to make people interact with architecture; the relation in this model is dialectical, as the building adapts itself to the environment and to the human needs, while the building at the same time changes the user behaviour. the people who use these buildings should not be thought of as “users” but instead as “participants”. m. novak uses the term transactive intelligence, to define architectural intelligence that not only interacts, but that transacts and transforms both the user and itself (silva, 2005). in the 1980s and 1990s, an explosion of development began to take place within the field of computer science. out of this, fields such as “intelligent environments” (ie) were formed to study spaces with embedded computation and communication technologies, creating spaces that bring computation into the physical world. intelligent environments are defined as spaces in which computation is seamlessly used to enhance ordinary activity (tilder and blostein, 2009). the advantages of the digital realm. “life adds “information to matter” to make adaptable shapes and 6 systems” (benyus, 2011). the same concept should be applied to the human industry and human constructions. smart buildings, able to make decisions, actions and evolving at the same time, can be developed from this application. some research had been done in this respect to get a human-like reaction. collective behaviour started to take place in the digital realm. actually in parallel to advances in ecological design, the digital realm has proliferated, becoming ubiquitous as our prosthetic extension to the world. during its first half-century the digital realm has generally been a top-down system. according to p. hasdell (2006), the potential of the digital – as complex autonomous systems that behave in ways more akin to living things in the natural world – is only now beginning to be actualized. as the digital realm evolves, new forms of distributed computing are employing cognitive, sensory, and interactive abilities, such as inbuilt feedback mechanisms and predictive and collective behaviours. the overall characteristics of our digital technology more closely approximate, and are able to interact with, human and natural systems. as n. k. hayles (1999) points out, essential decision-making processes in complex systems have developed in ways that now require both human and computer input. in this concept the natural and the artificial are increasingly united. the developing second order of cybernetic theory has a big role in this respect. the development of distributed cognitive environments in which humans and computers interact in hundreds of ways daily often unobtrusively has transformed data and information into a flow independent of its material base and creating the possibility for a new condition that links data and computer networks with human networks. n. k. hayles (1999) speaks of this condition not as dichotomy between the real and virtual but rather as space in which the natural and artificial are increasingly entwined. the 2005 united nations international telecommunications union report, “the internet of things”, outlines an increasing degree of embedded computing within our everyday environments, a proliferation of computing to the extent that interactions between multiple embedded parts may in the near future, outnumber actual human-computer interactions. this ubiquitous distributed computing will impact our notion of the environment and the interaction between entities (artificial or natural) within those environments (hayles, 1999; hasdell, 2006; tilder and blostein, 2009). this conceptually is related to the field of cybernetics or more precisely “new” or “second order” cybernetics in its rediscovery and redefinition in the 1970s. in the 1970s, new cyberneticians emerged in multiple fields, but especially in biology. the ideas of h. maturana, f. varela and h. atlan, according to j. p. dupuy (1982), “realized that the cybernetic metaphors of the program upon which molecular biology had been based rendered a conception of the autonomy of the living being impossible”. consequently, these thinkers were led to invent a new cybernetics. chilean biologists f. varela and h. maturana defined the term auto-poiesis as a conceptual mechanism: “an auto-poietic is a machine organized, (defined as a unity), as a network of processes of production (transformation and destruction of components which (i) through their actions and transformations continuously regenerate and realize the network of processes (relations) that produced them and (ii) constitute it as a concrete unity in space in which they (the components) exist by specifying the topological domain of its realization as such a network.” auto-poiesis or “self-creation” describe the cybernetic or regulating systems that give rise to and maintain biological cells and living systems within this concept (glow, 1992). the flow of energy and matter (molecules) is considered integral to the overall autonomy of the system as is the systems processes of cognition. because h. maturana’s and f. varella’s cybernetic theory of auto-poiesis refers to closed or bounded biological systems – in other words an organism’s capacity to make and maintain itself – it allows innumerable parallels to a more biological definition of ecology (gans and kuz, 2003). more specifically, as computing develops, employing cognitive, sensory, and interactive attributes as inbuilt feedback mechanisms, the overall behavioural characteristics of a digital system are increasingly able to engage the complex dynamics of both human and natural systems. emerging fusions of the natural and the digital are only just beginning to engage issues of biomimesis, emergent properties, environmental responsiveness, autonomous behaviours, and artificial ecosystems, in which a truly hybrid natural and digital environment, a “second nature” arises. second nature as it is commonly understood is an acquired behaviour practiced long enough to become innate or “natural”. it is also a learned physical or emotional response that modifies our relation to the world and allows us in this case to access both the natural and digital. emerging fields of research on morphological, digital and media ecologies are beginning to extend the concept of ecology beyond the natural biotope. recently, some researchers started to consider ecology as not the exclusive domain of the biologist. ecology can share commonalities and relationships facilitated by increasingly open “meshwork” between the physical and the virtual, the nature and the “second nature” and make them one unity. ecology in this meaning includes nature, second nature, and the virtual world. 2.4. examples m. wigginton and j. harris (2002) in their book “intelligent skin” give a good practical example of design ecology. it highlights an exciting new approach to the area, where the shell of the building responds to external changes and internal demands similar to the animal’s skin. the prime objective is to control internal environments through a responsive building fabric rather than by an energy consuming building services systems. the authors examine the potential for integral intelligence which is similar to the brain when it is connected to the building envelope-skin. they are suggesting an architecture model with flexible movable skin (giving some wall sections as a model for skin) working through a computing system. in his model 7 there is a continuous exploring and evolution of information technology and smart materials which have allowed a new category of bio mimicry design to be created (wigginton and harris, 2002). the eastgate centre in harare, zimbabwe, typifies the best of green architecture and ecologically sensitive adaptation. the country’s largest office and shopping complex is an architectural marvel in its use of biomimicry principles. the mid-rise building, designed by architect m. pearce, has no conventional air-conditioning or heating, yet stays regulated year round with dramatically less energy consumption using design methods inspired by indigenous zimbabwean masonry and the self-cooling mounds of african termites (atkinson, 1995; doan, 2012; pearce, 2014). termites in zimbabwe build gigantic mounds inside of which they farm a fungus that is their primary food source. the fungus must be kept at exactly 30.56 degrees celsius, while the temperatures outside range from 1.67 degrees celsius at night to 40 degrees celsius during the day. the termites achieve this remarkable feat by constantly opening and closing a series of heating and cooling vents throughout the mound over the course of the day. with a system of carefully adjusted convection currents, air is sucked in at the lower part of the mound, down into enclosures with muddy walls, and up through a channel to the peak of the termite mound. the industrious termites constantly dig new vents and plug up old ones in order to regulate the temperature (doan, 2012). the eastgate centre, largely made of concrete, has a ventilation system which operates in a similar way as shown in figures 1 and 2. outside air that is drawn in is either warmed or cooled by the building mass depending on which is hotter, the building concrete or the air. it is then vented into the building’s floors and offices before exiting via chimneys at the top. the complex also consists of two buildings side by side that are separated by an open space that is covered by glass and open to the local breezes. air is continuously drawn from this open space by fans on the first floor. it is then pushed up vertical supply sections of ducts that are located in the central spine of each of the two buildings. the fresh air replaces stale air that rises and exits through exhaust ports in the ceilings of each floor. ultimately it enters the exhaust section of the vertical ducts before it is flushed out of the building through chimneys (doan, 2012). the eastgate centre uses less than 10 percent of the energy of a conventional building its size (pearce, 2014). these efficiencies translate directly to the bottom line: eastgate’s owners have saved 3.5 million $ alone because of an air-conditioning system that did not have to be implemented. outside of being eco-efficient and better for the environment, these savings also trickle down to the tenants whose rents are 20 percent lower than those of occupants in the surrounding buildings (atkinson, 1995; doan, 2012). who would have guessed that the replication of designs created by termites would not only provide for a sound climate control solution but also be the most cost-effective way for humans to function in an otherwise challenging context (doan, 2012). fig. 1. the self-cooling mounds of african termites (doan, 2012) fig. 2. the concept behind zimbabwe passive design (doan, 2012) another approach was that of mit’s intelligent room project directed by m. coen, which was created to experiment with different forms of natural, multimodal human-computer interaction (hci) by embedding computational smarts into everything with which the users come in contact. the goal was to allow computers to participate in activities that have never previously involved computation and to allow people to interact with computational systems the way they would with other people (atkinson, 1995). the developments in ie were essentially fuelled by the concept of “ubiquitous computing” (a term coined in 1988 by m.weiser as a postdesktop model of human-computer interaction) (brooks and coen, 1994). 8 ubiquitous computing can be defined as computation thoroughly integrated into everyday objects and activities, and is often regarded as the intersection of computer science, behavioural sciences, and design. in ubiquitous computing, a user engages many computational devices and systems simultaneously in the course of ordinary activities, and may not necessarily even be aware that they are doing so. m. weiser described this as “the age of calm technology, when technology recedes into the background of our lives” (atkinson, 1995). another example can be seen through founder t. d’estree sterk and partner r. skelton. they are working on shape-changing “building envelopes” using “actuated tensegrity” structures – a system of rods and wires manipulated by pneumatic “muscles” that serve as the building’s skeleton, forming the framework of all its walls. sensor/computer/actuator technologies are used to produce d’estree sterk’s intelligent envelopes and structures that “seek fresh relationships between the “building” and “use””, according to interactive architecture organization. the buildings are covered by skins with the ability to alter their shape as the social and environmental conditions of the spaces within and around each building change. by connecting the skeleton to embedded, intelligent systems, d’estree sterk and his crew are creating smart structures that are light, robust and capable of making extensive shape changes without consuming a lot of energy (butcher, 2006). 2.5. the suggested model this paper is suggesting an integrated model that is connecting all the above designing techniques while adding new dimensions. we aim to create a real continuity between objectarchitecture, environment and human behaviour as the main three bases for which is called a “second nature”. we are looking forward for architecture that can keep a symbiotic relation with nature and humans. we talked and expanded about how architects can design a building to work like an organism. it may have systems of senses, bones (structure), muscles (moving parts), skins (shell) and a brain (digital) that know how to respond. also this adaptable architecture can satisfy the human needs too. this arises from the building’s ability to predict the behaviour and needs of the inhabitants by having observed them over a period of time. this building, instead of being programmed to perform certain actions, essentially programs itself by monitoring the environment and sensing actions performed by the users. at the same time these buildings have an effect on the users’ behaviour. there is a strong connection between the two, buildings and inhabitants. architecture should work similar and in total harmony with nature and humans. connected deeply through a “multiple-loop” system in which one enters into a “conversation”: a continual and constructive information exchange between nature and human. that goes to the degree that it becomes part of that natural entity and it is hard to know the edges between the three. the relation in this model is totally dialectical; it goes further than mimicking. these smart buildings, in some ways, would “come alive” and may do more. i will call this ambitious architecture a “smart dialectical architecture”. 3. conclusion this paper demonstrates that all the current environmental trends come up with only partial solutions. they started from the assumption that there is a separation between human and nature. this artificial separation works mostly for the human advantage. a new ambitious environmental approach is suggested. this trend should start based on a new interactive philosophy between human, architecture, and nature. the core of this approach is: human is part of this ecosphere and should work in harmony within the ecosphere. the relationships are symbiotic where all entities are contributing to the whole ecosphere. coming from this philosophy, the paper suggests a new model of building design that makes architecture work in total harmony with and welded into nature. it functions in the same way as ecologies. the functional concepts in the fields of biology and ecology are used to suggest the techniques to create a new architecture. mimicking the processes in nature using new cybernetic technology are the new techniques for “bio-interactive buildings”. the resulting “modern ecologies” based on a “second nature” unify the natural and the artificial into one entity. this ecology would be a continual dynamic relationship between matter, energy, and information in a specific medium (environment). the relationship in this design model is totally dialectical going further than just mimicking. it would be hard to separate what is life and what is matter. these smart buildings, in some ways, would “come alive”. acknowledgement to professor john robinson, i thank him for his guidance throughout his great course (history and philosophy of environmental thought) and for inspiring me to go far to pursue the ideas of sustainability. references ameriks k. 2002. hegel’s aesthetics: new perspectives on its response to kant and romanticism. bulletin of the hegel society of great britain, 6(45), 72–92. atkinson j. 1995. emulating the termite. the zimbabwean review 3(1), 16–19. benyus j. 2011. biomimicry is innovation inspired by nature. scientific american, october, 1–3. bilung l. 2000. specification and design of reactive systems. doctoral thesis submitted to university of california, berkeley. biomimetics. available at: http://en.wikipedia.org/wiki/ biomimetics (accessed 24 april 2014). brooks r. a., coen m. 1994. the intelligent room project, aizu, japan. butcher d. 2006. shape-shifting structures adapt to environment. industry market trend, september, 1–2. doan a. 2012. biomimetic architecture. available at: http:// inhabitat.com/building-modelled-on-termites-eastgatecentre-in-zimbabwe (accessed 24 april 2014). dupuy j. p. 1982. the autonomy of social reality: on the contribution of the theory of systems to the theory of society. 9 in: khalil e. l., boulding k. e. (eds.) order and complexity. cambridge, cambridge university press. evans m. what is biomimicry? design emulating nature. available at: http://sustainability.about.com/od/greenbuilding/a/ what-is-biomimicry.htm (accessed 24 april 2014). freigang c., kremeier j. 2003. architectural theory: from the renaissance to the present”. taschen. gans d., kuz. 2003. organic approach to architecture. wiley academy. glow m. 1992. alienation from nature: marx and environmental politics. alternatives, ucl press. hasdell, p. 2006. artificial ecologies: second nature emergent phenomena in constructed digital – natural assemblages. leonardo electronic almanac 7(14). available at: http:// leoalmanac.org/journal/vol_14/lea_v14_n07-08/phasdell. asp> (accessed 24 april 2014). hayles n. k. 1999. an interview/dialogue with albert borgmann and n. k. hayles on humans and machines. available at: http://www.press.uchicago.edu/misc/chicago/borghayl. html (accessed 24 april 2014). naess a. 1999). the shallow and the deep, long-range ecology movements: a summary. in: witoszek n., brennan, a. (eds.) philosophical dialogues: arne naess and the progress of ecophilosophy. oxford, new york, rowman and littlefield publishers inc., 3–7. pearce m. eastgate development harare. available at: http://www. mickpearce.com/works/office-public-buildings/eastgatedevelopment-harare/ (accessed 24 april 2014). responsive architecture. available at: http://en.wikipedia.org/ wiki/responsive_architecture (accessed 24 april 2014). royall e. 2010. defining biomimicry: architectural applications in systems and products. utsoa seminar in sustainable architecture. sullivan l. h. 1967. a system of architectural ornament according to the philosophy of man power. new york, eakins press. silva c. 2005. liquid architectures: marcos novak’s territory of information. master thesis submitted to louisiana state university. tilder l., blostein b. 2009. design ecologies. essays on the nature of design. new york, princeton architectural press. wigginton m., harris j. 2002. intelligent skin. oxford, butterworth-heinemann. received 2014 01 07 accepted after revision 2014 05 09 amal wasfi – ceo, amcordic design and consulting, bc, canada; graduate student, university of british columbia, sala, vancouver, canada. main research area: sustainable architecture. address: 1108-37 40 albert street, burnaby, bc, canada. e-mail: amal@amcordic.com e lectronic version available w w w. s a c e . k t u . l t 75 jsace 3/8 journal of sustainable architecture and civil engineering vol. 3 / no. 8 / 2014 pp. 75-82 doi 10.5755/j01.sace.8.3.7472 © kaunas university of technology received 2014/06/30 accepted after revision 2014/09/03 obtaining porous ceramics using shredded paper and foamglass pellets aleksandrs korjakins*, liga upeniece, liga tomase riga technical university, institute of materials and structures department of building materials and products kalku street 1, lv-1658, riga, latvia *corresponding author: aleksandrs.korjakins@rtu.lv within this research, carbonized clay, chamotte, as well as burn–out additives – widespread fillers (shredded paper and foamglass pellets) are used for the acquisition of porous ceramics, despite the fact that these fillers are not frequently used as burnable filler in traditional ceramics. the investigation of optimal mix content of raw materials, burning treatment was developed for obtaining improved mechanical properties of porous ceramics. the physical-mechanical properties of obtained ceramics were evaluated. proportion of dry clay, shredded paper, foamglass pellets, chamotte and water used in the investigations varied, changing the amount of fillers in order to obtain the samples with better mechanical properties. components of dry mixture for samples with shredded paper are dosed according to mass, where dry, milled clay was 63 – 69 %, shredded paper 2 – 12 %, water – 25%, but chamotte 0 – 4 %. when making porous ceramics using foamglass pellets as burnable filler, clay and water were used, where dry, milled clay was 57 – 69 %, water – 25 %, but foamglass pellets 6 – 18 %. following results were obtained for the samples with shredded paper used as a filler: shrinkage after the drying from 1.33 % up to 8.78 %, shrinkage after burning – 3.33-11.56%, density – 1256.64-1567.97 kg/m3, water absorption – 9.23-16.70 % and compressive strength – 1.17-4.66 mpa. while for samples with foamglass pellets used as a filler following results were obtained: shrinkage after the drying – 2.22 – 3.08%, shrinkage after burning – 5.44 – 6.11 %, density – 861.71 – 1178.34 kg/ m3, water absorption – 8.33 – 10.21 % and compressive strength – 1.15 – 1.94 mpa. porous ceramic materials obtained within this research are breathing; they are not only thermally stable materials, but also resistant to thermal impacts, corrosion and are easy in processing. obtained results of the research testify that these porous ceramics materials have great potential of application, but speaking about the material usage for load-bearing constructions, strength indicators must be improved by following researches using nanoadditives, the fillers such as glass and fire clay, developing the technology of producing (mix contents, drying and burning processes) ceramics which improve compressive strength indicators of the sample. the following investigation will be devoted to developing more effective material with relation density/ stiffness by controlling thermal conductivity properties. keywords: : ecological materials, insulation material, ceramics, production waste obtaining porous ceramics using shredded paper and foamglass pellets http://dx.doi.org/10.5755/j01.sace.8.3.7472 journal of sustainable architecture and civil engineering 2014/3/8 76 introduction within last hundred years, ceramics as the material has changed a lot due to the modernization of traditional ceramics industry and implementation of new and unusual functions in modernized ceramics. nowadays ceramics is modern material which can be successfully used in numerous spheres – from materials of ceramics up to social life, construction and other traditional products of ceramics up to the present time miniature computers, television, cars, planes and spacecraft and other modern technique developments. current general civilization progress is not conceivable without ceramics (sedmale 2010). due to its unique featured, modernized ceramics can and could be used as replacement material instead of other usual materials in building sector and as the material of new possibilities for innovative technology systems. in order to provide successful operation of those materials, ceramic constructions must be suitable for particular materials and production processes. from the point of perspective of ceramics materials, it is planned not only to replace traditional ceramics, but to develop completely new solutions from traditional materials. ceramics materials are not used in construction very frequently, but in electric and thermal isolation because it has high resistance indicators and very low thermal expansion. on the contrary characteristics of ceramics materials are particularly stable because plastic deformations almost do not exist. strength in a compression can be reached ten times more than in the bend and tension. in comparison with metals, ceramics materials are suitable for high temperatures because only particularly high temperatures can affect ceramics materials. those materials offer equally perfect features for corrosion and wear resistance (indriksone 2013). regardless of the modernization of ceramics and numerous changes, it is well known and used from ancient times and its raw material – clay is widely spread in the upper seams of earth (kurshs and stinkule 1997). porous ceramics nowadays are successfully used in the filtration and has a high potential of usage also in the production of heat insulation materials thus obtaining the material which combine high resistance that can compete with other heat insulation and constructive materials. problem of house renovation is very actual in latvia and other eastern europe countries, and it requires not only enormous investments but also evaluation of different benefits. besides economically opportune heat insulation materials which are flammable, less respiratory and produced abroad, we can also place materials of porous ceramics which have been produced from local raw materials, are inflammable, do not mildew, rot, are respiratory and harmless for the environment and people living in a house. nowadays porous ceramic can be obtained in several ways: using contents of monofraction raw materials, foam formation method, using burn-out additive method and forming of pores in a chemical way. within this research, burn-out additive method is used. the basis of this method is mixing fire-resistant material with hard and burn-out organic substances. sawdust is traditionally burnable filler used for production of the porous ceramics. it is widely researched both in latvia by obtaining samples with a strength of 10 mpa to 12 mpa in a density up to 1.5 g/cm3, by using 25 % woodchip and burning the clay in a 950 – 960 °c temperature (sedmale et al. 2009) as well as in leading russian scientific centers, where samples were obtained that were up to 17 mpa strong upon compression (salahov et al. 2011). comparatively low resistance at the high porosity can be mentioned as obstacle for the development of porous ceramics heat insulation, but application of nanotechnologies can be considered as solution thus forming ceramic solid matter nano-crystals (salahov et al. 2008). it is known that mechanical strength can be significantly improved when grain size is reduced to e lectronic version available w w w. s a c e . k t u . l t 77 nanometer scale. composites with nanograins have several advantages in that they possess improved properties (such as mechanical, electrical, thermal, ionic conducting, catalytic, and optical). besides, nanoscale ceramic powders offer the possibility of manufacturing dense ceramics at low sintering temperature (khalil 2012). within the research widespread fillers – shredded paper and foamglass pellets, which are not frequently used as burnable filler in traditional ceramics, were used for the acquisition of porous ceramics. carbonized clay with volume mass – 1600 kg/m3 and humidity level of 24 % as well as ground chamotte were used for sample preparation, where the organic filler – shredded paper and nonorganic foamglass pellets are used as burnable filler. the chemical composition of clay is given in table 1. used materials component sio 2 al 2 o 3 fe2o3 mno amount, % 49.5 13.04 5.14 0.071 component mgo na 2 o k 2 o p 2 o 5 amount, % 3.68 0.63 3.64 0.138 component tio 2 cao cr 2 o 3 so 3 amount, % 0.757 8.69 0.008 0.05 component other amount, % 14.656 abbreviation c la y, % w at er , % s hr ed de d pa pe r, % c ha m o tt e, % f o am g la ss pe ll et s, % sp6 69 25 6 sp2c4 69 25 2 4 sp12 63 25 12 fp6 69 25 6 fp9 66 25 9 fp12 63 25 12 fp18 57 25 18 table 1 chemical composition of clay table 2 composition of the samples the regular foamglass grain size used in present research was in the range 4-8 mm. the bulk density of these pellets is 150 kg/m3 and volume density is 270 kg/m3. paper is shredded in 7mm wide strips, grammage 80g/m2. proportion of dry clay, shredded paper, chamotte and water used in the investigations varied, changing the amount of shredded paper, and amount of chamotte in order to obtain the samples with better mechanical properties. components of dry mixture were dosed according to mass, where dry, milled clay was 63 – 69 %, shredded paper 2 – 12 %, water – 25%, but chamotte 0 – 4 %. when making porous ceramics using foamglass pellets as burnable filler, clay and water were used. all the components were dosed according to mass, where dry, milled clay was 57 – 69 %, water – 25 %, but foamglass pellets 6 – 18 %. for greater visibility the composition of the samples is shown in table 2. mould at the size 5x5 cm for sides was used for samples (6 samples of each composition) where foamglass pellets and shredded paper was utilized as burnable filler. journal of sustainable architecture and civil engineering 2014/3/8 78 methods when making the porous ceramic material, great attention has been paid to the raw material in the clay and mineralogical and chemical composition. during the presented research quartz has been not used in porous ceramics producing. since it reduces the technological characteristics – complicates sintering process, also reduces strength and, in certain cases, frost resistance of the samples as well. as well quartz worsens the plastics of ceramic mass, but reduces the contraction of the sample after drying and burning. cao and mgo (table 1) existing in their composition promote sintering of ceramics mass, advancing formation of pores. in the beginning, clay was dried in the drying oven and ground in retsch pm 400 mill for 30 minutes in dry condition. when all of the required components are prepared, they are dosed in the required amount and mixed in dry condition, gradually adding water till the sufficiently homogenous mixture for sample making is obtained. samples were dried in two different ways: using the dry in natural conditions for 7 days and artificial drying in binder fed drying-case for 48 hours at 70°c. shrinkage of samples was evaluated for fig. 1 sample burning graph after burning samples were refrigerated for 48 hours by gradual decrease of their temperature from 1090 °c to 20 °c . fig. 1. sample burning graph sample preparation process is summarized in table 3. table 3. sample preparation process abbre viation preparation of the components dosage and mixing burning refrigerating sp2c4 clay was dried in drying oven and ground for 30 minutes. chamotte was dried. all the componen ts were dosed according their mass and mixed in dry condition, gradually adding water all the samples were burnt 1 time by gradual increase of temperatu re. max.temp erature was 1090ºc 48 hours by temperat ure decheas e to 20 ºc. sp6 clay was dried in drying oven and ground for 30 minutes. sp12 fp6 fp9 fp12 fp18 water absorption, volumetric mass and compressive strength were stated for the obtained samples. water absorption of the samples was evaluated using standart test method for water absorption of plastics astm d570but compressive strength of the samples were tested in accordance with latvian standart (lvs) en 679:2005 “determination of the compressive strength of autoclaved aerated concrete”. 4. results the goal of the given research is to obtain a porous ceramic material with specific features of strength and density, thus achieving a material that could be used to insulate buildings and burnable fillers, such as shredded paper and foamglass pellets were used for its production. to achieve the goal of the research it was necessary to select the composition of formation mixture, drying and burning regimes and determine the physical – mechanical and structural parameters of ceramic samples and to select the best composition of formation mixture and drying/burning regimes in order to obtain porous and at the same time resistant materia using the local clay as the main material. several types of porous ceramic materials were obtained during research. compressive strength tests were performed, as well as their density and water absorption was determined. volumetric mass of samples where shredded paper was used as the burnable filler in the amount of 2-12%, reached 1256.64 – 1567.97 kg/m3, by respective decrease of volumetric mass if the amount of burnable filler are increased. while the volumetric mass of samples where foamglass pellets were used as the burnable filler was from 861.71 kg/m3, if the amount of filler is 18 %, to 1178.34 kg/m3, if the amount of foamglass pellets is 6 % (see fig. 2). fig. 2. volumetric mass of the samples shrinkage of samples was stated after their drying and after burning. for samples where foamglass pellets were used as the burnable filler, shrinkage after the natural drying was from 1.33 % up to 6.89 %, and the least shrinkage was recognized at the greatest amount of paper 12 %, but the greatest shrinkage at the amount of paper 6 %. after the natural drying the shrinkage was from 2.22 % up to 8.78 % accordingly and the least shrinkage was recognized upon the usage of 12 % of shredded paper, but the greatest upon the usage of 2 % of shredded paper and 4 % of chamotte. by the summarization of obtained results it can be seen that shrinkage after the natural drying is 1.1 – 1.7 less that shrinkage after the artificial drying. shrinkage after the natural drying of samples where foamglass pellets were used as burnable filler, is from 2.22 % up to 3.08 %, and the least shrinkage was recognized for the samples with greater content of foamglass pellets (18%), but the greatest – for the samples with least content of foamglass pellets (6%). shrinkage after the burning of samples where shredded paper was used as burnable filler was from 3.33 % to 11,56 %, but for the samples, where foamglass pellets was used – 5.44 %– 6.11 %, in both cases the least shrinkage was recognized for the samples with greater content of the burnable filler (see fig.3.). each of the above mentioned cases. after drying samples were burnt one time by gradual increase of temperature. within the range of temperature 0 °c up to 150 °c, samples were kept for 3 hours in order to ensure that upon the vaporization of excessive water there are no cracks in the porous ceramic samples. temperature in the range from 150-800 °c was increased per 5 °c/min or 130 min in total, but from 800-1090 °c per 2 °c/min or 145 min in total. at the maximal temperature 1090 °c, samples were kept for 2 hours in order to completely burn all of them (see fig.1). after burning samples were refrigerated for 48 hours by gradual decrease of their temperature from 1090 °c to 20 °c . sample preparation process is summarized in table 3. water absorption, volumetric mass and compressive strength were stated for the obtained samples. water absorption of the samples was evaluated using standart test method for water absorption of plastics astm d570but compressive strength of the samples were tested in accordance with latvian standart (lvs) en 679:2005 “determination of the compressive strength of autoclaved aerated concrete”. abbreviation p re pa ra ti o n o f th e co m po ne nt s dosage and mixing burning refrigerating sp2c4 clay was dried in drying oven and ground for 30 minutes. chamotte was dried. all the components were dosed according their mass and mixed in dry condition, gradually adding water all the samples were burnt 1 time by gradual increase of temperature. max. temperature was 1090ºc 48 hours by temperature dechease to 20 ºc. sp6 clay was dried in drying oven and ground for 30 minutes. sp12 fp6 fp9 fp12 fp18 table 3 sample preparation process e lectronic version available w w w. s a c e . k t u . l t 79 after burning samples were refrigerated for 48 hours by gradual decrease of their temperature from 1090 °c to 20 °c . fig. 1. sample burning graph sample preparation process is summarized in table 3. table 3. sample preparation process abbre viation preparation of the components dosage and mixing burning refrigerating sp2c4 clay was dried in drying oven and ground for 30 minutes. chamotte was dried. all the componen ts were dosed according their mass and mixed in dry condition, gradually adding water all the samples were burnt 1 time by gradual increase of temperatu re. max.temp erature was 1090ºc 48 hours by temperat ure decheas e to 20 ºc. sp6 clay was dried in drying oven and ground for 30 minutes. sp12 fp6 fp9 fp12 fp18 water absorption, volumetric mass and compressive strength were stated for the obtained samples. water absorption of the samples was evaluated using standart test method for water absorption of plastics astm d570but compressive strength of the samples were tested in accordance with latvian standart (lvs) en 679:2005 “determination of the compressive strength of autoclaved aerated concrete”. 4. results the goal of the given research is to obtain a porous ceramic material with specific features of strength and density, thus achieving a material that could be used to insulate buildings and burnable fillers, such as shredded paper and foamglass pellets were used for its production. to achieve the goal of the research it was necessary to select the composition of formation mixture, drying and burning regimes and determine the physical – mechanical and structural parameters of ceramic samples and to select the best composition of formation mixture and drying/burning regimes in order to obtain porous and at the same time resistant materia using the local clay as the main material. several types of porous ceramic materials were obtained during research. compressive strength tests were performed, as well as their density and water absorption was determined. volumetric mass of samples where shredded paper was used as the burnable filler in the amount of 2-12%, reached 1256.64 – 1567.97 kg/m3, by respective decrease of volumetric mass if the amount of burnable filler are increased. while the volumetric mass of samples where foamglass pellets were used as the burnable filler was from 861.71 kg/m3, if the amount of filler is 18 %, to 1178.34 kg/m3, if the amount of foamglass pellets is 6 % (see fig. 2). fig. 2. volumetric mass of the samples shrinkage of samples was stated after their drying and after burning. for samples where foamglass pellets were used as the burnable filler, shrinkage after the natural drying was from 1.33 % up to 6.89 %, and the least shrinkage was recognized at the greatest amount of paper 12 %, but the greatest shrinkage at the amount of paper 6 %. after the natural drying the shrinkage was from 2.22 % up to 8.78 % accordingly and the least shrinkage was recognized upon the usage of 12 % of shredded paper, but the greatest upon the usage of 2 % of shredded paper and 4 % of chamotte. by the summarization of obtained results it can be seen that shrinkage after the natural drying is 1.1 – 1.7 less that shrinkage after the artificial drying. shrinkage after the natural drying of samples where foamglass pellets were used as burnable filler, is from 2.22 % up to 3.08 %, and the least shrinkage was recognized for the samples with greater content of foamglass pellets (18%), but the greatest – for the samples with least content of foamglass pellets (6%). shrinkage after the burning of samples where shredded paper was used as burnable filler was from 3.33 % to 11,56 %, but for the samples, where foamglass pellets was used – 5.44 %– 6.11 %, in both cases the least shrinkage was recognized for the samples with greater content of the burnable filler (see fig.3.). the goal of the given research is to obtain a porous ceramic material with specific features of strength and density, thus achieving a material that could be used to insulate buildings and burnable fillers, such as shredded paper and foamglass pellets were used for its production. to achieve the goal of the research it was necessary to select the composition of formation mixture, drying and burning regimes and determine the physical – mechanical and structural parameters of ceramic samples and to select the best composition of formation mixture and drying/ burning regimes in order to obtain porous and at the same time resistant materia using the local clay as the main material. several types of porous ceramic materials were obtained during research. compressive strength tests were performed, as well as their density and water absorption was determined. volumetric mass of samples where shredded paper was used as the burnable filler in the amount of 2-12%, reached 1256.64 – 1567.97 kg/m3, by respective decrease of volumetric mass if the amount of burnable filler are increased. while the volumetric mass of samples where foamglass pellets were used as the burnable filler was from 861.71 kg/m3, if the amount of filler is 18 %, to 1178.34 kg/m3, if the amount of foamglass pellets is 6 % (see fig. 2). results fig. 2 volumetric mass of the samples fig. 3 average shrinkage after the burning of the samples, which were dried for 48 hours at 70°c shrinkage of samples was stated after their drying and after burning. for samples where foamglass pellets were used as the burnable filler, shrinkage after the natural drying was from 1.33 % up to 6.89 %, and the least shrinkage was recognized at the greatest amount of paper 12 %, but the greatest shrinkage at the amount of paper 6 %. after the natural drying the shrinkage was from 2.22 % up to 8.78 % accordingly and the least shrinkage was recognized upon the usage of 12 % of shredded paper, but the greatest upon the usage of 2 % of shredded paper and 4 % of chamotte. by the summarization of obtained results it can be seen that shrinkage after the natural drying is 1.1 – 1.7 less that shrinkage after the artificial drying. shrinkage after the natural drying of samples where foamglass pellets were used as burnable filler, is from 2.22 % up to 3.08 %, and the least shrinkage was recognized for the samples with greater content of foamglass pellets (18%), but the greatest – for the samples with least content of foamglass pellets (6%). shrinkage after the burning of samples where shredded paper was used as burnable filler was from 3.33 % to 11,56 %, but for the samples, where foamglass pellets was used – 5.44 %– 6.11 %, in both cases the least shrinkage was recognized for the samples with greater content of the burnable filler (see fig.3.). fig. 3. average shrinkage after the burning of the samples, which were dried for 48 hours at 70°c compressive strength was determined for all the samples, the resulting values can be seen in fig.4. fig. 4. compressive strength of the samples, mpa greatest compressive strength – 4.66 mpa has been stated for the samples, where 2 % of shredded paper and 45 % of chamotte were used as a filler, where chamotte provides necessary stiffness by making stable frame during the sample burning process. compressive strength of other samples where shredded paper was used as a filler, was from 1.17 mpa to 1.54 mpa, by respective increase upon decreasing of the amount of filler. in samples where foamglass pellets were used instead of shredded paper, the compressive strength is from 1.15 mpa up to 1.94 mpa by respective increase upon decreasing of the amount of filler. water absorption of the samples was obtained during the research, which is summarized in table 4. obtained data demonstrates that the greatest water absorption – 16.70 % is for the samples with filler of 12 % paper, but the least – 8.33 % for samples with 18 % of foamglass pellets. totally the difference between the volume of water absorption for samples with shredded paper filler and foamglass pellet filler is 4.58 % – 50.12 %. table 4. water absorption of the samples amount of filler water absorption, % 6 % shredded paper 9.23 2 % shredded paper, 4 % chamotte 10.70 12 % shredded paper 16.70 6 % foamglass pellets 9.55 9 % foamglass pellets 10.21 12 % foamglass pellets 9.11 18 % foamglass pellets 8.33 5. discussion during the research the acquisition of porous ceramics was practically demonstrated by using shredded paper and foamglass pellets as the filler upon changing the amount and type of filler and obtaining the material with various physically mechanic features. volumetric mass of samples where shredded paper was used as the burnable filler in the amount of 2-12 %, reached 1256.64 kg/m3 – 1567.97 kg/m3, while the volumetric mass of samples where foamglass pellets were used as the burnable filler was from 861.71 kg/m3, if the amount of filler is 18 %, to 1178,34 kg/m3. the efficiency of application a shredded paper is very low, since reducing volume density to about 20 %, the strength of the ceramics is reducing for almost 10 times. it may be explained by chips form of paper particles that create a lot of plain voids in the specimens destroying homogeneity of material structure. at the same time particles of paper absorb the water from the mix and worse plasticity of this one. density of porous ceramics samples can be easily regulated by changing the amount and type of foamglass pellets, but if the amount of filler is increased and amount of water is kept at the same level, plasticity of the mixture decreases and it is more difficult to get homogeneous mixture as well as to work it in the moulds. besides the decrease of plasticity we must also consider the decrease of compressive strength which is obtained by increasing the porosity of sample (decrease of density) therefore recognition and acquisition of mutual proportion between the density and resistance of sample plays essential role thus ensuring the acquisition of optimal material. resistance indicators for the samples where shredded paper is used as the filler, are from 1.17 mpa up to 4.66 mpa, but for samples with foamglass pellets – 1.15 mpa up to 1.94 mpa. there were a lot of shrinkage cracks in the specimens with foamglass pellets as fillers. this fact can explain low strength properties of the ceramic specimens. obtained results of the research testify that these porous ceramics materials have great potential of application, but speaking about the material usage for loadbearing constructions, strength indicators must be improved by following researches using nanoadditives, the fillers such as glass and fire clay, developing the technology of producing (mix contents, drying and burning processes) ceramics which improve resistance indicators of the sample. shrinkage of obtained samples with foamglass pellets after the drying is from 1.33 mpa up to 8.78 % which due to the information mentioned in literature sources (рыбьев et al 1987) means that listed clay is less plastic (shrinkage less than 6 %) and medium plastic (shrinkage from 6 % up to 10%). journal of sustainable architecture and civil engineering 2014/3/8 80 compressive strength was determined for all the samples, the resulting values can be seen in fig.4. greatest compressive strength – 4.66 mpa has been stated for the samples, where 2 % of shredded paper and 45 % of chamotte were used as a filler, where chamotte provides necessary stiffness by making stable frame during the sample burning process. fig. 3. average shrinkage after the burning of the samples, which were dried for 48 hours at 70°c compressive strength was determined for all the samples, the resulting values can be seen in fig.4. fig. 4. compressive strength of the samples, mpa greatest compressive strength – 4.66 mpa has been stated for the samples, where 2 % of shredded paper and 45 % of chamotte were used as a filler, where chamotte provides necessary stiffness by making stable frame during the sample burning process. compressive strength of other samples where shredded paper was used as a filler, was from 1.17 mpa to 1.54 mpa, by respective increase upon decreasing of the amount of filler. in samples where foamglass pellets were used instead of shredded paper, the compressive strength is from 1.15 mpa up to 1.94 mpa by respective increase upon decreasing of the amount of filler. water absorption of the samples was obtained during the research, which is summarized in table 4. obtained data demonstrates that the greatest water absorption – 16.70 % is for the samples with filler of 12 % paper, but the least – 8.33 % for samples with 18 % of foamglass pellets. totally the difference between the volume of water absorption for samples with shredded paper filler and foamglass pellet filler is 4.58 % – 50.12 %. table 4. water absorption of the samples amount of filler water absorption, % 6 % shredded paper 9.23 2 % shredded paper, 4 % chamotte 10.70 12 % shredded paper 16.70 6 % foamglass pellets 9.55 9 % foamglass pellets 10.21 12 % foamglass pellets 9.11 18 % foamglass pellets 8.33 5. discussion during the research the acquisition of porous ceramics was practically demonstrated by using shredded paper and foamglass pellets as the filler upon changing the amount and type of filler and obtaining the material with various physically mechanic features. volumetric mass of samples where shredded paper was used as the burnable filler in the amount of 2-12 %, reached 1256.64 kg/m3 – 1567.97 kg/m3, while the volumetric mass of samples where foamglass pellets were used as the burnable filler was from 861.71 kg/m3, if the amount of filler is 18 %, to 1178,34 kg/m3. the efficiency of application a shredded paper is very low, since reducing volume density to about 20 %, the strength of the ceramics is reducing for almost 10 times. it may be explained by chips form of paper particles that create a lot of plain voids in the specimens destroying homogeneity of material structure. at the same time particles of paper absorb the water from the mix and worse plasticity of this one. density of porous ceramics samples can be easily regulated by changing the amount and type of foamglass pellets, but if the amount of filler is increased and amount of water is kept at the same level, plasticity of the mixture decreases and it is more difficult to get homogeneous mixture as well as to work it in the moulds. besides the decrease of plasticity we must also consider the decrease of compressive strength which is obtained by increasing the porosity of sample (decrease of density) therefore recognition and acquisition of mutual proportion between the density and resistance of sample plays essential role thus ensuring the acquisition of optimal material. resistance indicators for the samples where shredded paper is used as the filler, are from 1.17 mpa up to 4.66 mpa, but for samples with foamglass pellets – 1.15 mpa up to 1.94 mpa. there were a lot of shrinkage cracks in the specimens with foamglass pellets as fillers. this fact can explain low strength properties of the ceramic specimens. obtained results of the research testify that these porous ceramics materials have great potential of application, but speaking about the material usage for loadbearing constructions, strength indicators must be improved by following researches using nanoadditives, the fillers such as glass and fire clay, developing the technology of producing (mix contents, drying and burning processes) ceramics which improve resistance indicators of the sample. shrinkage of obtained samples with foamglass pellets after the drying is from 1.33 mpa up to 8.78 % which due to the information mentioned in literature sources (рыбьев et al 1987) means that listed clay is less plastic (shrinkage less than 6 %) and medium plastic (shrinkage from 6 % up to 10%). fig. 4 compressive strength of the samples, mpa compressive strength of other samples where shredded paper was used as a filler, was from 1.17 mpa to 1.54 mpa, by respective increase upon decreasing of the amount of filler. in samples where foamglass pellets were used instead of shredded paper, the compressive strength is from 1.15 mpa up to 1.94 mpa by respective increase upon decreasing of the amount of filler. amount of filler water absorption, % 6 % shredded paper 2 % shredded paper, 4 % chamotte 12 % shredded paper 6 % foamglass pellets 9 % foamglass pellets 12 % foamglass pellets 18 % foamglass pellets 9.23 10.70 16.70 9.55 10.21 9.11 8.33 table 4 water absorption of the samples water absorption of the samples was obtained during the research, which is summarized in table 4. obtained data demonstrates that the greatest water absorption – 16.70 % is for the samples with filler of 12 % paper, but the least – 8.33 % for samples with 18 % of foamglass pellets. totally the difference between the volume of water absorption for samples with shredded paper filler and foamglass pellet filler is 4.58 % – 50.12 %. discussion during the research the acquisition of porous ceramics was practically demonstrated by using shredded paper and foamglass pellets as the filler upon changing the amount and type of filler and obtaining the material with various physically mechanic features. volumetric mass of samples where shredded paper was used as the burnable filler in the amount of 2-12 %, reached 1256.64 kg/m3 – 1567.97 kg/m3, while the volumetric mass of samples where foamglass pellets were used as the burnable filler was from 861.71 kg/m3, if the amount of filler is 18 %, to 1178,34 kg/m3. the efficiency of application a shredded paper is very low, since reducing volume density to about 20 %, the strength of the ceramics is reducing for almost 10 times. it may be explained by chips form of paper particles that create a lot of plain voids in the specimens destroying homogeneity of material structure. at the same time particles of paper absorb the water from the mix and worse plasticity of this one. density of porous ceramics samples can be easily regulated by changing the amount and type of foamglass pellets, but if the amount of filler is increased and amount of water is kept at the same level, plasticity of the mixture decreases and it is more difficult to get homogeneous mixture as well as to work it in the moulds. besides the decrease of plasticity we must also consider the decrease of compressive strength e lectronic version available w w w. s a c e . k t u . l t 81 which is obtained by increasing the porosity of sample (decrease of density) therefore recognition and acquisition of mutual proportion between the density and resistance of sample plays essential role thus ensuring the acquisition of optimal material. resistance indicators for the samples where shredded paper is used as the filler, are from 1.17 mpa up to 4.66 mpa, but for samples with foamglass pellets – 1.15 mpa up to 1.94 mpa. there were a lot of shrinkage cracks in the specimens with foamglass pellets as fillers. this fact can explain low strength properties of the ceramic specimens. obtained results of the research testify that these porous ceramics materials have great potential of application, but speaking about the material usage for load-bearing constructions, strength indicators must be improved by following researches using nanoadditives, the fillers such as glass and fire clay, developing the technology of producing (mix contents, drying and burning processes) ceramics which improve resistance indicators of the sample. shrinkage of obtained samples with foamglass pellets after the drying is from 1.33 mpa up to 8.78 % which due to the information mentioned in literature sources (рыбьев et al 1987) means that listed clay is less plastic (shrinkage less than 6 %) and medium plastic (shrinkage from 6 % up to 10%). total shrinkage of the drying and burning for both samples is from 4.66 % up to 12.11 % which confirm to the total shrinking level from 5 % up to 18 % mentioned in literature sources (higerovics et al. 1972). by the application of natural drying the main advantages are the less shrinkage, less consumption of resources and more easy technological process if we compare with the artificial drying. but at the same time artificial drying provides essential decrease of drying time thus speeding up the process of material production. water absorption for both types of obtained samples was from 8.33 % up to 16.70 % which confirm to the total shrinkage level from 8 % up to 20 % mentioned in literature sources (higerovics et al. 1972). decreasing water absorption with increasing volume of glass pellets in ceramic may be explained by decreasing permeability of materials for water due to covering inner surface of voids by glass. it means the obtained material should improve the thermal insulation properties by saving breathing possibility. if we compare foamglass pellets and shredded paper fillers, the second one has the deficiency of heterogeneous structure of pore which is related to the orientation of shredded paper and its disposition in the sample that has negative effect to the physical and mechanic features of samples by decreasing their compressive strength. but the following must be considered – usage of shredded paper in the production of porous ceramics can be more effective by additional treatment before mixing with clay and other fillers. the following investigation will be devoted to developing more effective material with relation density/stiffness by controlling thermal conductivity properties. within the research samples of porous ceramics were developed upon application of two different burnable fillers – foamglass pellets and shredded paper by stating the shrinkage (after the artificial and natural drying), density, water absorption and compression strength of acquired samples. following results were obtained for the samples with shredded paper used as a filler: shrinkage after the drying from 1.33 % up to 8.78 %, shrinkage after burning – 3.33-11.56%, density – 1256.641567.97 kg/m3, water absorption – 9.23-16.70 % and compressive strength – 1.17-4.66 mpa. while for samples with foamglass pellets used as a filler following results were obtained: shrinkage after the drying – 2.22 – 3.08%, shrinkage after burning – 5.44 – 6.11 %, density – 861.71 – 1178.34 kg/m3, water absorption – 8.33 – 10.21 % and compressive strength – 1.15 – 1.94 mpa. by comparing the features of both obtained materials we can see that samples with shredded conclusions journal of sustainable architecture and civil engineering 2014/3/8 82 paper used as the filler have better compressive strength indicators, but samples with foamglass pellets – less density. if we compare the shrinkage, samples with the paper used as the filled have less shrinking of the dry after the burning. therefore for the acquisition of necessary strength and density indicators of the material, in the following researches it is essential to find the optimal filler and its amount. porous ceramic materials after improvement of their strength properties can be used as constructive building materials, they are breathable, do not rot and they are resistant against heat and thermal impact, corrosion, deterioration and aggressive environment. production of porous ceramics materials where foamglass pellets are used as the burnable filler, allows create more effective ceramics, creating high added value for the final product. aleksandrs korjakins professor riga technical university, institute of materials and structures, head of department of building materials and products main research area building materials an building technology address kalku street 1 lv-1658, riga, latvia tel. +371 26422442 e-mail: aleks@latnet.lv liga upeniece phd student riga technical university, institute of materials and structures, department of building materials and products main research area ecological materials, ceramic address kalku street 1 lv-1658, riga, latvia tel. +371 26356332 e-mail: liga.upeniece@rtu.lv brian o’rourke ms. student riga technical university, department of building materials and products main research area building materials an building technology address kalku street 1 lv-1658, riga, latvia tel. +371 28635851 e-mail: liga.tomase@rtu.lv about the authors acknowledgment khalil k. a.. 2012. advanced sintering of nano-ceramic materials, ceramic materials – progress in modern ceramics. isbn: 978-953-51-0476-6, intech, 66. higerovičs m. 1972. autoru kolektīvs. būvmateriāli. – rīga, zvaigzne, 325. indriksone e. 2013. silīcija karbīda keramika. īpašība sun izmantošanas iespējas. rīga, 83. kurshs v., stinkule a. 1997. latvijas derīgie izrakteņi. riga, the university of latvia, 67. latvian standart lvs en 679:2005, 2005. determination of the compressive strength of autoclaved aerated concrete. рыбьев и.а. kоллектив авторов. 1987. общий курс строительных материалов. москва, вышая школа, 583. references sedmale g. 2010. keramika. ķīmija un tehnoloģija. rīga, rtu izdevniecība, 225. sedmale g., cimmers a., sedmalis u. 2009. charasteristics of illite clay and compositions for porous building ceramics production, institue of silicate materials, riga technical univesity, issn 1392 -1231, chemine technologija, volume 2 (51). salahov a., tagirov l., salahova r., parfenov v., ljadov n. 2011. поры и прочностные характеристики строительных материалов, строительные материалы, volume 12, 25 -27 salahov a., livada a., salahova r. 2008. нанотехнология – гарантия заданных свойств керамических материалов,строительные материалы, 27-29. standart test method for water absorption of plastics astm d570, 1998 (2010). the financial support of the latvian council of science is acknowledged (project 12.0412). 21 journal of sustainable architecture and civil engineering 2022/2/31 *corresponding author: ahlam.labin@aabu.edu.jo sustainable neighbourhood evaluation criteria – design and urban values (case study: neighbourhoods from al-mafraq, jordan) received 2022/03/22 accepted after revision 2022/08/09 journal of sustainable architecture and civil engineering vol. 2 / no. 31 / 2022 pp. 21-38 doi 10.5755/j01.sace.31.2.30953 sustainable neighbourhood evaluation criteria – design and urban values (case study: neighbourhoods from al-mafraq, jordan) jsace 2/31 http://dx.doi.org/10.5755/j01.sace.31.2.30953 ahlam eshruq labin*, saqer sqour, abdelmajeed rjoub, rami al shawabkeh, safa al husban al al-bayt university, faculty of engineering, architecture engineering, mafraq 25113, jordan introduction abstract a sustainable neighbourhood is critical in preserving the environment for future generations, as various societies are suffering from increasing reliance on vehicles and low social interaction. this study aims to compare two neighbourhoods in terms of implementing the sustainable neighbourhood criteria. this study is based on eight sustainable neighbourhood evaluation criteria related to design and urban values are: regional issues, compacted form, mixed land-use, connectivity, pedestrian-oriented building, public sphere of the neighbourhood, relationship with transit, and walkability. university district and jordan villa compound newly developed residential neighbourhoods located in al-mafraq city in jordan were chosen as a case study to evaluate the sustainable neighbourhood criteria. the primary and secondary data were obtained from various resources, including; previous studies that related to the topic, site surveys and personal interviews. the results show that the university district is more sustainable and walkable than the jordan villa compound; due to several reasons as the grid pattern of planning and the high population density. the importance of this study comes from implementing the sustainable neighbourhood evaluation criteria to develop communities to become more sustainable and walkable. keywords: neighbourhood, sustainable neighbourhood, walkability. people have tended to live close together in fragmented areas. they share a place for practical, economical, sociological, and psychological reasons and form a neighbourhood. the clustering of these neighbourhoods has created towns, villages, and cities (kohon 2018). the neighbourhood is a social, economic, and physical environment; the social dimension includes residents’ daily needs, a variety of housing types and tenure patterns, and social diversity such as; age, income, and cultural background. the economic dimension includes the availability of several house’ prices and various services and amenities. and the physical dimension includes design and planning values (abbas and najat 2019). a neighbourhood is the crucial planning entity in modern residential planning theories. recently, the goal of urban planning and housing projects has been to provide an appropriate setting for people to live now and in the future that is environmentally, socially, and economically healthy; a place that is safe, well planned, and built to last which forms the concept of a sustainable neighbourhood (butera 2018). journal of sustainable architecture and civil engineering 2022/2/31 22 literature review urbanisation and industrialisation produce several communities’ troubles; many communities are challenging the growing dependence on vehicles, resulting in low-density development and sprawling development patterns. the most significant theories in urban planning are by clarence stein and henry wright. in an illustration of the town plan called “a town for the motor age” they highlighted that the primary purpose was to construct a town for the automobile age (sharifi 2016). globally, climate change is another problem resulting from urbanisation due to decreased dependence on walkability and high reliance on vehicles. as a result, people realised that there is an urgent need to use sustainable approaches to dealing with the climate change phenomenon, as in most city centres, the focus is on the streets and traffic movement, which means pedestrians are limited on the sidewalks (butera 2018). several initiatives to solve the problems of urbanisation; un-habitat (2013) proposes a method that examines existing sustainable urban planning theories in order to build a sustainable relationship between urban inhabitants and urban space. it is built on three pillars: vibrant street life, walkability, and affordability. the fundamental characteristics of a sustainable neighbourhood include social sustainability through having good environmental potential, such as garden provision and proximity to parks (choguill 2007, al-hagla 2008, and hong 2011). sustainable communities’ components include governance, transport and connectivity, services, environment, economy, housing and the built environment, sociology, and culture (al-haggle 2008, review 2004). the main objectives of this study are to: 1. determine the sustainable neighbourhood criteria related to the design and urban values. 2. evaluate the chosen case studies in terms of applying the sustainable neighbourhood criteria. the study relies on relevant literature on sustainable neighbourhoods such as un-habitat (2013), elgadi and ismail (2016), jasim et al. (2018), abbas and najat (2019), al-hagla (2008), azmi and karim (2012), and knapskoga et al. (2019) to develop an evaluation model. a physical survey was conducted to assess the sustainable neighbourhood indicators for jordan villa compound and the university district in al-mafraq city, jordan, by field observation at the site. neighbourhood planning from unplanned housing design to the industrial revolution, the concept of neighbourhood unit was influenced by suffocating traffic, the regression of the city environment, high overcrowding, the distance from basic community facilities, and the insecurity of children going to school (kohon 2018). clarence perry's model, which he developed in 1929, provided explicit recommendations for the spatial allocation of houses and community services. perry proposed the neighbourhood concept as a means of addressing transportation issues; accessible from the place of residence to the community centre and elementary schools are considered basics. residents can obtain appropriate access to community services such as adequate shared play spaces, an elementary school, retail shops, and facilities in the neighbourhood. according to clarence perry's model, the neighbourhood unit occupies about 160 acres with a population of between 5,000 and 6,000 people. this improves the low-density dwelling district with10 families per acre population. it is expected that the children walk from their houses more than one-quarter mile to the elementary school, which has between 1,000 and 1,200 students (singhal 2011, azmi and abdul karim 2012). perry's determined six essential elements of good neighbourhood design: 1. for a safer environment, the main street should form the neighbourhood’s boundaries; consequently, it should not run through the residential areas. 2. for low-volume traffic movement, cul-de-sacs are used to plan the internal streets that permeate the residential area. 23 journal of sustainable architecture and civil engineering 2022/2/31 3. the population should be sufficient to sustain the elementary school in the neighbourhood. 4. the neighbourhood's focal point is the elementary school, which is placed parallel to the neighbourhood's boundaries with other services; 5. the neighbourhood's maximum radius should be no more than a quarter-mile, which is the maximum distance a child can walk to any elementary school; 6. the shops should be located at the significant traffic crossroads at the edge of the neighbourhoods. arnold whittick (1974) defined a neighbourhood, as “an integrated and planned urban area related to the larger community of which it is a part, and consisting of residential districts, schools, shopping facilities, religious buildings, open spaces, and service industry”, a neighbourhood as a scheme of arrangement for the family life community (kohen 2018). a neighbourhood means a physical environment in which essential community facilities are within walking distance; a setting in which residents can easily walk to a shopping centre and children will not have to cross crowded streets on their way to school, where employees can find the appropriate transportation to and from work. it is a residential area with a playground nearby where children can play in a safe and healthy setting (engelyan et al. 2005, azmi and abdul karim 2012). a playground is a gathering place where residents socialise and children play. every dwelling unit should be within a quarter-mile to a half-mile of it. while the shops should be located on the main streets and near the intersections of primary or secondary thoroughfares; to be easily accessible by both pedestrian and vehicular traffic, the average walking distance of the service area is between a quarter-mile to one mile (sharifi 2016). nowadays, there are several contemporary neighbourhood’s movements, such as. a. the compacted city is one of the contemporary residential neighbourhood concepts based on the self-sufficient residential neighbourhoods concerning their daily needs. walking to the centre takes about 10-15 minutes. the local centres with mixed land-use are connected with other centres by public transport. the main goal is to reduce the use of cars and rely mainly on public transportation (abbas and najat 2019, hamdan et al. 2021). b. urban villages, the concept of urban villages is based on independent communities grouped around a defined high-density centre in order to achieve a balance between housing, work and urban life. the scale of the urban villages provides ease of walking and emphasises mixed land-use, which provides an enjoyable and visually rich urban environment through a variety of building styles and attractive facades. this pattern offers a friendly pedestrian environment that calms the traffic movement and enhances the priority of pedestrians over cars (abbas and najat 2019, hamdan et al. 2021). c. the new urbanisation movement was called the “livable neighbourhood”. it focuses on designing neighbourhoods based on a human scale and achieving the inhabitants’ social needs (sharifi 2016, abbas and najat 2019). the term 'new urbanisation' includes a range of ideas related to the residential neighbourhood, such as: traditional neighbourhoods and new traditional neighbourhoods. traditional neighbourhood seeks to create compacted neighbourhoods; containing different types of residential units, a friendly pedestrian environment, mixed land-use, and a well-defined identity that encourages citizens to take responsibility for the preservation and development of the environment. thus, the daily activities are within walking distance as the residential units are near transport stations, connected to networks of streets and close to commercial and institutional activities (carmona 2015, abbas and najat 2019, sqour et al. 2022b). new traditional neighbourhood seeks to design small towns returning to the traditional patterns of small towns that are walkable and have a clear urban structure, a combination of uses and sevejournal of sustainable architecture and civil engineering 2022/2/31 24 ral types of housing units. moreover, it is characterised by a harmonious design of its buildings and spaces. it strives to provide a physical environment that encourages the social interaction and street patterns that allow for walkability with a collective sense of a traditional town (abbas and najat 2019). d. pedestrian enclaves are defined as a balanced mixed land-use within a half-mile radius, or five minutes walking distance from the transit station, which is smaller than the town and contains housing, offices, retail, and daycare shops. it creates an environment that provides a variety of transportation options. thus, the other features of the pedestrian enclaves come from giving an equilibrium distribution of jobs, housing and services (stanislava and chin 2019). e. transport-oriented development, caltrop peter applied the idea of urban planning and design in traditional neighbourhood development into a regional context by connecting existing places and new communities along transit corridors using light rail technology. thus, each transit station can stimulate a mixed land-use, a high-density planned neighbourhood within a radius of 400-800 meters, organised around pedestrian-friendly streets, squares, and parks (walters and luise 2004). f. smart development, which aims to create an active and compacted neighbourhood, serves as a critical component in reducing urban growth and conserving the local environment by emphasising the development of mixed land-use, various transportation options, and several housing types, as well as adopting effective locations that increase the population density around centres to reduce the distance from the daily activities, thereby lowering the infrastructure cost and conserving the open spaces (quan 2019, antwi-afaria et al. 2021). sustainable neighbourhood sustainability is known as a development that meets the needs of the present without compromising the ability of future generations to meet their own needs. nowadays, neighbourhoods are constantly implementing adjustments to become more sustainable. there are a variety of sustainable approaches to neighbourhood application, such as the social approach, which understands the neighbourhood as a ‘community’ (choguill 2007, al-hagla 2008). the ecological approach emphasises on neighbourhood's particular site attributes. it describes the neighbourhood as an ecosystem environment that creates its own microclimatic conditions while providing the essential local habitat for humans with enough comfort and sustenance (butera 2018). the major goals of the sustainable neighbourhoods are to reduce greenhouse gas emissions by reducing dependency on automobiles, creating a healthy environment by promoting an active lifestyle (especially walking), increasing street safety by reducing vehicle/pedestrian collisions, increasing accessibility and freedom of choice by making more facilities accessible locally, equity and social inclusion by offering a diverse selection of facilities within easy walking distance, increasing the value of local community by facilitating accessible social networks, and increasing local self-determination by increasing inhabitants control (al-hagla 2008, hong 2011). a sustainable neighbourhood is a safe, well-planned, and long-lasting environment in which people can live at the present time and in the future that is environmentally, socially, and economically healthy (elgadi and ismail 2016; kohon 2018). greening the environment, reducing greenhouse gas emissions, and allowing people to live comfortably by providing secure neighbourhoods that minimise resource exhaustion, cultural disruptions, environmental degradation, and social instability are all strategies that could be used to achieve sustainability (engelyan et al. 2005, jiboye and ogunshakin 2010, antwi-afaria et al. 2021). the sustainable neighbourhood is socially cohesive and diverse, with a mix of housing types and employment opportunities, and it gives priority to walking, cycling and public transit. also, it encourages energy efficiency. at the same time, residential areas are located near recreational and commercial facilities with pedestrian and bike networks (hong 2011). 25 journal of sustainable architecture and civil engineering 2022/2/31 according to al-hagla (2008), the community perspective of a sustainable neighbourhood includes; the social provision that improves access to facilities, built space, and open space, economic sustainability, such as job opportunities and economic buoyancy, social sustainability that contains health, community safety, and equity and choice. while there are two perspectives on applying sustainability, they are: global ecology and natural resources. the global ecology dimension includes climate, stability, energy in transport, energy in buildings, and biodiversity. and the natural resources dimension provides air quality, water, land, soil, and minerals. sustainable neighbourhood criteria one of the initiatives is to design a neighbourhood that improves the inhabitant’s walkability, which means that the planning and design desires will be enhanced toward a more sustainable life (al-hagla 2008). al-hagla (2008) evaluated the sustainability performance as combining three separate green space typologies: parks and gardens, children's play areas, and sports facilities. al-hagla (2008) identified three key characteristics of open space in the sustainable neighbourhood: space management, space function, and the role of items inside areas. accordingly, he concluded a parameter for assessing the performance of the sustainable community. another study was conducted to measure the willingness to buy houses in sustainable neighbourhoods in malaysia. it concludes that the house buyers are ready to buy houses in a sustainable community, so the governments are responsible for putting a vision and guidelines for the sustainable neighbourhood (hong 2011). azmi and karim (2012) investigate the link between walkability and a sustainable neighbourhood. they created a model that incorporated three key elements: neighbourhood design, neighbourhood walkability, and the applicability of sustainable concepts. neighbourhood walkability promotes facility accessibility, measuring the distance to community facilities and assessing the willingness to walk before deciding to drive. moreover, the adaptability of a sustainable neighbourhood includes several principles, such as location and clustering of community facilities, for example; local shops, playgrounds, and schools, react to places such as hot climate conditions, which affects walking, and diversity, which affects the safety and convenience while walking. un-habitat (2013) proposed an approach to promote sustainable urban development by establishing livable and efficient neighbourhoods. this approach is based on five principles that support three key features of a sustainable community: compact, integrated, and interconnected. 1. adequate space for streets and an efficient street network. the street network should occupy at least 30% of the land and at least 18 km of street length per km². 2. there is a high population density of at least 15,000 people per km², which means 150 people/ ha or 61 people per acre. 3. mixed land-use, at least 40% of floor space should be allocated for economical use in any neighbourhood. 4. social combination, the availability of houses in different price ranges and tenures in any given neighbourhood, 20% to 50% of the residential floor area should be for low-cost housing; and each tenure type should not be more than 50% of the total. 5. limited land-use specialisation, this is to limit single function blocks or neighbourhoods; single function blocks should cover less than 10% of any neighbourhood. sharifi (2016) traced the evolution of the 20th century planning movements to see how the principles have changed and how successful they have been in addressing the requirements of sustainable development. sharifi studied garden city, neighbourhood unit, modernism, neo-traditionalism, and eco-urbanism, respectively. journal of sustainable architecture and civil engineering 2022/2/31 26 elgadi and ismail (2016) reviewed the sustainable neighbourhood indicators and development. they found that the sustainable neighbourhood indicators for several countries are generally similar and only differ depending on their regional climate characteristics. a comparative study was accomplished to analyse the sustainability of six residential districts. the study relies on six architectural and planning criteria are; diversity, compactness, residential density, mixed land uses, transportation network efficiency, and permeability; the criteria were identified as sustainable factors for appraising the residential neighbourhood (jasim et al. 2018). jasim et al. (2018) concluded the main features of the sustainable neighbourhood that are transportation network efficiency, including two indicators: transportation network area, which must be sufficient, convenient, and not less than 30% of the neighbourhood area, and transportation network length. the neighbourhood’s population reaches 5,000 people per square kilometre for each community, equivalent to 150 people per hectare. arrange mixed land-use by allocating no less than 40% of the neighbourhood's area to economic uses. improve social unity, which means 20-50% housing units must be provided to low-income people, and each type of tenure should not exceed 50% of the total housing units in the neighbourhood. and the area of any use must be not less than 10% of the area specified for the neighbourhood (jasim et al. 2018). abbas and najat (2019) proposed several principles to achieve the development of the residential neighbourhood, including integrating the social, economic, and environmental aspects with the principles of the sustainable neighbourhood. they concluded that the sustainable residential neighbourhood model contains components of regional development as well as sustainability qualities. knapskoga et al. (2019) measure walkability in several neighbourhoods. they proposed several criteria for evaluating walkability that is divided into three groups: infrastructure and traffic, urbanity, and surroundings and activities. these criteria may be used to develop cities and areas to become more walkable and sustainable. based on the previous literature review, there are eight sustainable neighbourhood criteria, namely, regional issues, compacted form, mixed land-use, connectivity, pedestrian-oriented building, the public sphere of the neighbourhood, relationship with transportation, and walkability. 1. regional issues include the development of previously urbanised land, the proximity of the new product to the existing infrastructure, integration with public transport systems, the arranged growth of neighbourhoods in a rational manner within a comprehensive regional plan, and preserving open spaces (un-habitat 2013, elgadi and ismail 2016, jasim et al. 2018, abbas and najat 2019). 2. the compacted form includes arranging the neighbourhood around a well-defined centre and emphasising the boundaries of the neighbourhood (un-habitat 2013, elgadi and ismail 2016, jasim et al. 2018, abbas and najat 2019). 3. mixed land-use, which includes multiple types of activities focus activities on focal points, diversity of retail and service activities and integration of residential, economic, administrative and civil uses (un-habitat 2013, elgadi and ismail 2016, jasim et al. 2018, abbas and najat 2019). 4. connectivity indicator includes connection to the traffic network, safe pedestrian movement, providing green pedestrian paths, easy access to activities and residential movement paths directed to pedestrians and bicycles (un-habitat 2013, elgadi and ismail 2016, jasim et al. 2018, abbas and najat 2019). 5. pedestrian-oriented building indicator includes a human scale of buildings, attractive facades of buildings, defining streets and squares by the surrounding buildings and diversity in shapes and styles of buildings (elgadi and ismail 2016, jasim et al. 2018, abbas and najat 2019, sqour et al. 2022). 27 journal of sustainable architecture and civil engineering 2022/2/31 6. the public sphere of the neighbourhood indicator includes an emphasis on the locations of civil buildings, emphasise public spaces as places to accommodate social interactions, and emphasises on the third place like cafes and restaurants (elgadi and ismail 2016, jasim et al. 2018, abbas and najat 2019). 7. relationship with transportation indicator includes a convenient street for transportation and accessibility to bus stops (un-habitat 2013, elgadi and ismail 2016, jasim et al. 2018, abbas and najat 2019). 8. walkability indicator is divided into three groups: infrastructure and traffic, urbanity, and surroundings and activities (al-hagla 2008, azmi and abdul karim 2012, knapskoga et al. 2019). study area al-mafraq governorate is located in the northeast of jordan, 60 kilometers east of amman. it covers 26552 km2. it had a population of 58000 in 2017, making up 5.8% of jordan's population (sqour et al. 2016, department of statistics 2017). the study’s area is located in al-mafraq's new city centre, which contains two newly developed neighbourhoods, jordan villa compound (fig. 2) and the university district (fig. 3). the project provides an integrated environment with services and infrastructure, where roads, sidewalks, the electricity network, government schools, a commercial mall, retail shops, a mosque, public squares, and green open spaces with a total of 1343 housing units. it is located along the amman-damascus international highway, opposite the southern gate of al-albayt university and king talal military hospital (fig. 1). the residential units in the neighbourhoods provide several types, including: _ type a includes independent villas with various areas, a 217 m2 built-up area, is constructed on a plot of 350 m2, and a 250m2 built-up area and is constructed on a plot of 500m2-600m2. _ type b includes attached villas. each villa has a built-up area of 197 m2 and is constructed on a plot of 250–350 m2. _ type c includes 190 landed independent houses. each unit has a built-up area of 184m2 and it is constructed on a plot of 400 m2. methodology fig. 1 the master plan of the new city centre of al-mafraq journal of sustainable architecture and civil engineering 2022/2/31 28 _ type d includes 40 flats arranged in 10 residential buildings of two levels. each building has four flats with a 150m2 built-up area. _ type e includes flats built in residential buildings of four levels that offer 930 units with a 150m2 built-up area. the two neighbourhoods in al-mafraq, jordan were chosen by referring to officials of the municipality, the gis database delivered by the department of statistics census and land plots in the lands and survey department were used to identify the demographic features of the neighbourhood. the reason for choosing these neighbourhoods is the sustainability applicable in the development of the geographical area. the research has two sample schemes; the first sample represents jordan villa comfig. 2 jordan villa compound fig. 3 the university district pound with private houses of type a and type b, and the second sample scheme represents the university district containing landed houses of type c, flats of type d and type e (fig. 1). jordan villa compound includes 183 units built on 114000m2; it is characterised by a low population density of 920 residents. while the university district has 1160 residential units constructed on 247420m2. it is characterised by a high population density of around 5800 residents. the average number of household members is five persons. most residents work in governmental jobs near the neighbourhoods, such as al-albayt university or in the private sector in al-mafraq. to make the dwellings affordable for the households, the stone wasn’t used to cover the facades. concrete was used as a building material for the housing units in the two neighbourhoods, and solar panels were used for more energy efficiency in the jordan villa compound; as the units’ area is bigger than it in the university district. data collection this study is based mainly on the literature review to collect the secondary data; eight sustainable neighbourhood criteria were determined: regional issues, compacted form, mixed land-use, connectivity, pedestrian-oriented building, the public sphere of the neighbourhood, relationship with transportation, and walkability. then a physical survey was conducted to assess the sustainable neighbourhood criteria for jordan villa compound and the university district by field observation. the physical survey was used to collect the data and test the criteria by observation. observations can provide and reconfirm important information that can support the survey results. the combination of observation and surveys is a critical methodological approach for this study to observe how the existing conditions of the residential areas (functional, physical, social and psychological) influence sustainability. notes and picture taking of the residential areas should be the method of recording observations. results according to hong (2011) and after the field observations at jordan villa compound and the university district, they achieved some dimensions of sustainable neighbourhoods as; they are socially cohesive and diverse, with a mix of housing types and employment opportunities, and it gives priority to walking. also, they encourage energy efficiency by using the solar energy and sun panels. but the recreational and commercial facilities are not enough and need to improve. 29 journal of sustainable architecture and civil engineering 2022/2/31 table 1 conceptual model s u st ai na bl e n ei g hb o u rh o o d c ri te ri a criteria detailed indicators regional issues development of previously urbanised land proximity of the new development to the existing infrastructure integration with public transport systems neighbourhoods growth in a rational manner within a comprehensive regional plan preserving open spaces compacted form organise the neighbourhood around a well-defined centre emphasise the boundaries of the neighbourhood mixed landuse various types of activities focus activities on focal points diversity of retail and service activities integration of residential, economic, administrative and civil uses connectivity connected to traffic network safe pedestrian movement provide green pedestrians path easy access to activities residential movement paths directed to pedestrians and bicycles pedestrianoriented building human scale of buildings attractive facades of buildings defining streets and squares by the surrounding buildings diversity in shapes and styles of buildings public sphere of the neighbourhood emphasis on the locations of civil buildings emphasise public spaces as places to accommodate social interactions emphasis on the third place (cafes restaurants) relationship with transit provide convenient streets for transportation bus stops walkability infrastructure and traffic street or road character, pedestrians infrastructure, crossings, traffic volumes, speed levels, pollution and noise, traffic safety, universal design, and public transport connectedness urbanity density, proximity, connectedness, scale, orientation of buildings, block size, permeability, pedestrian network, urban structure, parking lots, urban space and parks, green, and street furniture surroundings and activities destinations, activities, people walking or staying, facades, mix of functions, vibrancy, maintenance, experienced safety, and wayfinding journal of sustainable architecture and civil engineering 2022/2/31 30 based on literature review there are eight sustainable neighbourhood criteria: regional issues, compacted form, mixed land-use, connectivity, pedestrian-oriented building, the public sphere of the neighbourhood, relationship with transit, and walkability (table 1). regional issues include development of previously urbanised land, the proximity of the new development to the existing infrastructure, integration with public transport systems, the neighbourhoods grow in a rational manner within a comprehensive regional plan, and preserving open spaces. all regional issues were considered while planning jordan villa compound and university district except the indicator of integration with public transport systems (table 2). the compacted form includes organising the neighbourhood around a well-defined centre and emphasising the neighbourhood’s boundaries. jordan villa compound and university district fulfil the two indicators (table 2). mixed land-use is essential to accommodate residents' daily requirements while minimising urban sprawl. economically mixed land-uses emphasise reducing long commutes, creating of self-sufficient neighbourhoods through the integration of residential, commercial, administrative, and civil services, allowing people to live close to their workplaces and shops (abbas and najat 2019). mixed land-use includes several indicators such as various types of activities, focus activities on focal points, diversity of retail and service activities and integration of residential, economic, administrative and civil uses. jordan villa compound and university district fulfil all indicators except integration of residential, economical, administrative and civil uses as the residential area is separate from other activities (table 2). there are multiple types of activities at jordan villa compound and university district, such as a play area, schools, shops and commercial mall, which are focused on focal points and are accessible to the residents of the neighbourhoods (fig. 1). connectivity aims to connect neighbourhoods with their surroundings by using hierarchical street designs (abbas and najat 2019). the connectivity indicator includes connection to the traffic network, safe pedestrian movement, providing green pedestrian paths, easy access to activities and residential movement paths directed to pedestrians and bicycles. jordan villa compound and university district satisfy all indicators except providing the green pedestrians paths (table 2). the pedestrian-oriented building criterion includes the human scale of buildings (sqour et al. 2022a) as the residential units vary from one floor to four floors, attractive facades of structures by using a pleasing height and suitable materials, defining streets and squares by the surrounding buildings and diversity in shapes and styles of buildings as there are several dwelling types in the neighbourhoods (abbas and najat 2019). diversity in shapes and styles of buildings isn’t available in the jordan villa compound as there is a typical pattern of building with various areas (table 2). neighbourhood design should include appropriate public spaces in which buildings and their features are organised to encourage pedestrians to walk and emphasise the relationship of buildings with streets in terms of proper setbacks and the creation of streets and squares with dynamic character. the intensive construction density and mixed land-use should be encouraged during neighbourhood design (abbas and najat 2019). the public sphere of the neighbourhood criterion includes emphasis on the locations of civil buildings, emphasis on public spaces as places to accommodate social interactions and focus on the third place like cafes and restaurants. jordan villa compound and university district satisfy all indicators excluding the indicator of emphasis in the third place (table 2). the neighbourhood structure must be adequately connected to public transportation in order to encourage users to use it. transportation should follow direct and logical routes to various destinations so that the routes work efficiently, and the transit points must be safe, comfortable, and 31 journal of sustainable architecture and civil engineering 2022/2/31 table 2 sustainable neighbourhood criteria and indicators criteria and indicators jordan villa compound university district criterion 1: regional issues 1 development of previously urbanised land √ √ 2 the proximity of the new development to the existing infrastructure √ √ 3 integration with public transport systems x x 4 neighbourhoods growth in a rational manner within a comprehensive regional plan √ √ 5 preserving open spaces √ √ regional issues score 4/5 4/5 criterion 2: compacted form 1 organise the neighbourhood around a well-defined centre √ √ 2 emphasise the boundaries of the neighbourhood √ √ compacted form score 2/2 2/2 criterion 3: mixed land-use 1 various types of activities √ √ 2 focus activities on focal points √ √ 3 diversity of retail and service activities √ √ 4 integration of residential, economic, administrative and civil uses x x mixed land-use score 3/4 3/4 criterion 4: connectivity 1 connected to traffic network √ √ 2 safe pedestrian movement √ √ 3 provide green pedestrians path x x 4 easy access to activities √ √ 5 residential movement paths directed to pedestrians and bicycles √ √ connectivity score 4/5 4/5 criterion 5: pedestrian-oriented building 1 human scale of buildings √ √ 2 attractive facades of buildings √ √ 3 defining streets and squares by the surrounding buildings √ √ 4 diversity in shapes and styles of buildings x √ pedestrian-oriented building score 3/4 4/4 criterion 6: the public sphere of the neighbourhood 1 emphasis on the locations of civil buildings √ √ 2 emphasise public spaces as places to accommodate social interactions √ √ 3 emphasis on the third place (cafes restaurants) x x the public sphere of the neighbourhood score 2/3 2/3 criterion 7: relationship with transit 1 provide convenient streets for transportation √ √ 2 bus stops x x relationship with transit score 1/2 1/2 journal of sustainable architecture and civil engineering 2022/2/31 32 well-designed (abbas and najat 2019). the relationship with transit includes a convenient street for transportation and accessibility to bus stops. based on the site visit, bus stops cannot be accessed by residents at jordan villa compound and the university district (table 2). the walkability criterion includes three groups of indicators: infrastructure and traffic, urbanity, and surroundings and activities. the score was arranged from 0-3; if the neighbourhood isn’t walkable, it is given 0, if the neighbourhood is somewhat walkable, it is given 1, if it is walkable, it is given 2, and if the neighbourhood is highly walkable, it is given 3. infrastructure and traffic indicator includes several attributes such as; street or road character that affect pedestrians’ walkability, whereas the use of street increases the walkability and the use of road decreases it. the availability of the sidewalks as a pedestrian infrastructure inspires pedestrians to walk. crossings as barriers and detours decrease the willingness of pedestrians to walk. if traffic volume and the speed level are high, that decreases the walkability. contrary relationship between pollution and noise and pedestrians’ walkability. while high traffic safety, universal design, and connectivity to public transit increase walkability. the highest score of infrastructure and traffic indicator is 27, if the neighbourhood achieves the attributes of high walkability. the urbanity indicator contains several attributes that affect walkability. population density, proximity and short distance, connected to the city structure, the building scale as small blocks, and the high permeability of the neighbourhood increase the pedestrians’ walkability. other attributes, such as building orientations, where pedestrians’ walkability increases if buildings are oriented along the street, while walkability decreases if buildings recede from the road. the urban structure of neighbourhoods affects walkability; the grid pattern increases walkability, and cul-de-sac decreases walkability. as well as, the increasing of parking lots negatively affects walkability. however, growing urban space and parks, trees on the streets, and street furniture all contribute to increasing walkability. the highest score on urbanity indicator is 39 if the neighbourhood achieves the attributes of high walkability. surroundings and activities indicator contains several attributes that positively affect walkability, such as; multiple destinations, multiple activities, many people walking or staying, a high mix of function, high vibrancy and high maintenance. moreover, the feel of safe and easy wayfinding rises the pedestrians’ walkability. the highest score for surroundings and activities indicator is 27 if the neighbourhood achieves the attributes of high walkability. walkability in jordan villa compound the first group of indicators is infrastructure and traffic; jordan villa compound achieves all indicators except the connectivity with public transportation. the second group is the urbanity indicators, the density is low, and the buildings are close together, so the walking distance is short. the district isn’t connected to the city structure, and the urban design is on a pedestrian scale. the residential buildings in the community are oriented along the street and built head-to-head to the sidewalk, which improves walkability. another relevant indicator is block size, which is small. permeability is low as the urban design of the neighbourhood is based on the cul-de-sac pattern, so pedestrians cannot choose between routes and take shortcuts. furthermore, the pedestrian network has a coherent area as no infrastructure creates barriers, and there are urban spaces and parks where pedestrians can stay, socialise, play and spend time. there isn’t enough street furniture and there aren’t enough street trees because of the desert weather where the district is located (table 3). in the last group of indicators, surroundings and activities, there are limited destinations and activities in the jordan villa compound, which decrease the pedestrian walkability and pleasure while walking in the area. few people are walking or staying in the open spaces; the dwellings have closed facades because of the fences around the villas and similarities in facade patterns. there are insufficient functions, only the play area. good maintenance and experienced safety are high, and easy wayfinding (table 3). 33 journal of sustainable architecture and civil engineering 2022/2/31 indicators attributes highly walkability walkable somewhat walkable not walkable infrastructure and traffic street or road character street √ road pedestrians infrastructure sidewalks √ no sidewalks crossings defined crossing at the same level √ barriers and detours for pedestrians traffic volumes low √ high speed levels low √ high pollution and noise low √ high traffic safety high √ low universal design high accessibility √ low accessibility public transport connectedness route connected to bus stops √ route not connected to bus stops infrastructure and traffic indicator score 24 urbanity density high √ low proximity short distance √ long distance connectivity connected to the city structure √ its own structure scale pedestrians √ vehicles oriented orientation of buildings buildings oriented along the street √ building receded from the street block size small blocks √ long/large blocks permeability high permeability √ not permeable pedestrian network coherent pedestrian network short cuts √ infrastructure as barriers for pedestrians urban structure grid √ cul de sac parking lots few √ many, making barriers urban space and parks many √ few/none green street trees, parks et. √ non greenery street furniture many √ few/none urbanity indicator score 22 surroundings and activities destinations multiple √ few or no one activities multiple √ few or no one people walking or staying many √ few or no one facades active √ closed mix of functions high √ low vibrancy high √ low maintenance high √ low experienced safety feels safe √ feels non safe wayfinding easy √ not easy surroundings and activities indicator score 16 walkability score 62 table 3. walkability in jordan villa compound journal of sustainable architecture and civil engineering 2022/2/31 34 walkability in the university district the university district achieves all the attributes of the infrastructure and traffic indicator except the connectivity with the public transportation. urbanity indicator score is 32, the density is high, the buildings are close together, so the walking distance is short. the district isn’t connected to the city structure, and the urban structure is on a pedestrian scale. the residential buildings in the district are oriented along the street and built head-to-head to the sidewalk, which improves walkability. another relevant attribute is block-size which is small, the permeability is high, and pedestrians can choose between routes and take shortcuts. furthermore, the pedestrian network has a coherent area as there is no infrastructure that creates barriers, and there are urban spaces and parks where pedestrians can stay, socialise, play and spend time. analyse (table 4). table 4 walkability in the university district indicators attributes highly walkability walkable somewhat walkable not walkable infrastructure and traffic street or road character street √ road pedestrians infrastructure sidewalks √ no sidewalks crossings defined crossing at the same level √ barriers and detours for pedestrians traffic volumes low √ high speed levels low √ high pollution and noise low √ high traffic safety high √ low universal design high accessibility √ low accessibility public transport connectedness routs connected to bus stops √ routs not connected to bus stops infrastructure and traffic indicator score 24 urbanity density high √ low proximity short distance √ long distance connectivity connected to the city structure √ its own structure scale pedestrians √ vehicles oriented orientation of buildings buildings oriented along street √ building receded from the street block size small blocks √ long/large blocks permeability high permeability √ not permeable pedestrian network coherent pedestrian network short cuts √ infrastructure as barriers for pedestrians urban structure grid √ cul de sac parking lots few √ many, making barriers urban space and parks many √ few/none green street trees, parks √ non greenery street furniture many √ few/none 35 journal of sustainable architecture and civil engineering 2022/2/31 indicators attributes highly walkability walkable somewhat walkable not walkable urbanity indicator score 32 surroundings and activities destinations multiple √ few or no one activities multiple √ few or no one people walking or staying many √ few or no one facades active √ closed mix of functions high √ low vibrancy high √ low maintenance high √ low experienced safety feels safe √ feels non safe wayfinding easy √ not easy surroundings and activities indicator score 18 walkability score 74 the last indicator is surroundings and activities; university district has few destinations and activities, which decreases the pleasure of pedestrian walking. walking or staying outside almost table 5 sustainable neighbourhood criteria score sustainable neighbourhood principles jordan villa compound university district 1 regional issues 4 4 2 compacted form 2 2 3 mixed land-use 3 3 4 connectivity 4 4 5 pedestrian-oriented building 3 4 6 the public sphere of the neighbourhood 2 2 7 relationship with transit 1 1 8 walkability 62 74 total score 81 94 are experienced by few people. the facades of the residential buildings are active facades. there aren’t enough functions, only the play area and vibrant street life, good maintenance, experienced safety is high, and easy wayfinding is understood (table 4). the sustainable neighbourhood score for the university district is 94, which is higher than the sustainable neighbourhood score for the jordan villa compound, which is 81 (table 5). the sustainable neighbourhood score was calculated for both jordan villa compound and the university district by summing all the principles scores (regional issues, compacted form, mixed land-use, connectivity, pedestrian-oriented building, the public sphere of the neighbourhood, relationship with transit and walkability). a neighbourhood is an area for residents to live, communicate, and get suitable access to community services. while a sustainable neighbourhood is an appropriate environment for people to live now and in the future that is environmentally, socially, and economically healthy; a place that is safe, well planned, and built to last. the importance of this study comes from employing the sustainable neighbourhood indicators to develop communities to become more sustainable, and producing a parameter that could be applied internationally; thus, it can be used to assess the sustainable neighbourhood. conclusion journal of sustainable architecture and civil engineering 2022/2/31 36 the present research explores an evaluation process for two newly developed neighbourhoods in al-mafraq in the northeast of jordan. jordan villa compound and the university district were chosen to be the cases in the study. to begin the research a set of criteria was developed to evaluate the sustainable neighbourhood. those criteria are grouped into eight components: regional issues, compacted form, mixed landuse, connectivity, pedestrian-oriented building, public sphere of the neighbourhood, relationship with transit and walkability, each of these components has its own attached attributes. after the physical survey was conducted, the results show that the social dimension is achieved by meeting the residents’ daily needs, supporting the variety of housing types and tenure patterns, and supporting the social diversity such as age, income, and cultural background. the economic dimension is achieved by offering several house’ prices and various services and amenities. moreover, the two neighbourhoods achieve most of the sustainable neighbourhood principles. in spite of the fact that the two neighbourhoods are close together, the sustainable neighbourhood score for the university district is 95, which is higher than the sustainable neighbourhood score for the jordan villa compound, which is 82. the reason is the availability of various house types, such as landed houses, flats of two-story buildings, and flats in four-level buildings. also, the dwelling facades at the university district were active. at the same time, it was closed at the jordan villas compound as the villas have more privacy and have fences around each unit, which prevent social interaction. additionally, the permeability in the university district is higher than in the jordan villa compound due to the urban design; the grid pattern was used to organise the neighbourhood activities at the university distract while the cul-de-sac pattern was used in the jordan villa compound. university district is more sustainable; as it is more walkable than jordan villa compound due to several reasons; firstly, the urbanity indicator of the university district is higher than jordan villa compound as the permeability and population density is high, while the population density is low at the jordan villa compound. secondly, surrounding and activities indicator is higher in the university district due to the high density, thus more people are walking or staying in the public spaces than in jordan villa compound. several factors affect the pedestrian’s walkability, including infrastructure and traffic, urbanity, and surroundings and activities. the urban design pattern affects walkability since the grid pattern of the neighbourhood increases walkability while the cul-de-sac pattern decreases walkability. moreover, high population density, connection with public transit, and the availability of multiple types of activities are factors that increase pedestrian walkability. the most critical factor that decreases the sustainable score in both jordan villa compound and the university district are: connected to public transport is unavailable and the green areas are limited due to the desert weather. while the indicator that raises the sustainability score for the two neighbourhoods and encourages the residents to live there are: the proximity to job opportunities, high safety in the neighbourhoods, and availability of essential facilities such as schools, universities, mosques, and government hospitals such as king talal hospital and women and children’s hospital. abbas, s.s., najat, r. f. residential neighbourhood development, analytical study of residential projects in contemporary trends. iraqi journal of architecture and planning, 2019; 15(1): 76-92. al-hagla, k. s. towards a sustainable neighbourhood: the role of open spaces. international journal of architectural research, 2008; 2:162-177. antwi-afaria, p., owusu-manub, d.g., thomas, ng s., asumadud, g. modeling the smartness or smart development levels of developing countries' cities. journal of urban management, 2021;10 (4): 369381. https://doi.org/10.1016/j.jum.2021.06.005 references 37 journal of sustainable architecture and civil engineering 2022/2/31 azmi, d.i., abdul karim, h. implications of walkability towards promoting sustainable urban neighbourhood. procedia social and behavioral sciences, 2012; 50: 204-213. https://doi.org/10.1016/j. sbspro.2012.08.028 butera, f.m. sustainable neighbourhood design in tropical climates. urban energy transition (second edition), renewable strategies for cities and regions, 2018; 51-73. https://doi.org/10.1016/b9780-08-102074-6.00017-6 carmona, m. re-theorizing contemporary public space: a new narrative and a new normative. journal of urbanism, 2015; 8 (4): 374-405. https:// doi.org/10.1080/17549175.2014.909518 choguill, c. l. the search for policies to support sustainable housing. habitat international, 2007; 31: 143-149. https://doi.org/10.1016/j.habitatint.2006.12.001 department of statistics. census of 2017. elgadi, a.a. and ismail, l.h. a review of sustainable neighbourhood indicators for urban development in libya. arpn journal of engineering and applied sciences, 2016; 11 (4). engel yan, j, kennedy, c. saiz, s. and pressnail, k. toward sustainable neighbourhood: the need to consider infrastructure interactions. canadian journal of civil engineering, 2005; 32: 45-57. https://doi. org/10.1139/l04-116 jasim, i. a., farhan, s. l. and attalla, a. t. sustainable neighbourhood comparative analysis of al kut neighbourhoods. journal of university of babylon for engineering sciences jubes, 2018; 26 (9): 302317. https://doi.org/10.29196/jub.v26i2.500 jiboye, a. d., ogunshakin, l. the place of the family house in contemporary oyo town, nigeria. journal of sustainable development, 2010; 3 (2): 117-128. https://doi.org/10.5539/jsd.v3n2p117 hamdan, h.a.m, andersen, p.h., boer, l. stakeholder collaboration in sustainable neighbourhood projects-a review and research agenda. sustainable cities and society, 2021; 68. https://doi.org/10.1016/j. scs.2021.102776 hong, t. measuring the willingness to bay for houses in a sustainable neighbourhood. international journal of environmental, cultural, economic and social sustainability, 2011; 7:1-12. https://mpra. ub.uni-muenchen.de/id/eprint/30446. https://doi. org/10.18848/1832-2077/cgp/v07i01/54854 knapskoga, m., hagena, o.h., tennøya, a., rynning, m.k. exploring ways of measuring walkability. transportation research procedia, 2019; 41: 264282. https://doi.org/10.1016/j.trpro.2019.09.047 kohon, j. social inclusion in the sustainable neighbourhood? idealism of urban social sustainability theory complicated by realities of community planning practice. city, culture and society, 2018; 15: 1422. https://doi.org/10.1016/j.ccs.2018.08.005 quan, s. j. smart design for sustainable neighbourhood development. energy procedia, 2019; 158: 6515-6520. https://doi.org/10.1016/j.egypro.2019.01.108 review e. skills for sustainable communities: the office of the deputy prime minister in sustainable communities: quality with quantity, riba, london, great britain, 2004. on web www.architecture.com sharifi, a. from garden city to eco-urbanism: the quest for sustainable neighbourhood development. sustainable cities and society, 2016; 20: 1-16. https://doi.org/10.1016/j.scs.2015.09.002 singhal, m. neighbourhood unit and its conceptualization in the contemporary urban context. institute of town planners, india journal, 2011; 8187 sqour, s., rjoub, a., alshawabkeh, r., al husban, s., al-taani, m.a.sh., eshruq labin, a. humanizing unfriendly buildings and spaces by architectural thought (case study: houses from jordan). civil engineering and architecture, 2022a; 10 (3): 1047-1055, 2022. https://doi.org/10.13189/cea.2022.100321 sqour, s., tarrad, m., alshawabkeh, r., eshruq labin, a. contribution of society and owners of buildings in conservation of architectural heritage in the arab world. (case study: "rawdat sudair, saudi arabia"). international journal of sustainable development and planning, 2022b; 17 (1): 127-133. https:// doi.org/10.18280/ijsdp.170112 sqour, s. m., rjoub, a., tarrad, m. development and trends of urban growth in mafraq city, jordan. architecture research, 2016; 6 (5): 116-122. doi: 10.5923/j.arch.20160605.02. stanislava, a., chin, j.t. evaluating livability and perceived values of sustainable neighbourhood design: new urbanism and original urban suburbs. sustainable cities and society, 2019; 47. https://doi. org/10.1016/j.scs.2019.101517 un-habitat. a new strategy of sustainable neighbourhood planning, 2013. at website: (http://unhabitat.org/wp-content/uploads/2014/05/5-principles web.pdf) walters, d., luise, l. design first -design-based planning for communities. first published, architectural press, oxford-uk, 2004. whittick, a. encyclopedia of urban planning. mcgraw-hill press, 1974. journal of sustainable architecture and civil engineering 2022/2/31 38 about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). dr. ahlam eshruq labin assistant professor architecture engineering department, faculty of engineering, al al-bayt university, jordan main research area architecture, housing theories and urban planning. address almafraq, jordan tel. 00962786744165 e-mail: ahlam.labin@aabu.edu.jo dr. saqer sqour associate professor architecture engineering department, faculty of engineering, al al-bayt university, jordan main research area architecture, history and theory of architecture and urbanism. islamic. architecture. address irbid, jordan tel. 00962797785367 e-mail: s_sqour@aabu.edu.jo dr. abdelmajeed rjoub professor architecture engineering department, faculty of engineering, al al-bayt university, jordan main research area housing theories and urban planning. address al mafraq, jordan tel. 00962779525000 e-mail: rjoub@aabu.edu.jo dr. rami al shawabkeh associate professor, head of architecture engineering department faculty of engineering, al al-bayt university, jordan main research area architecture -sustainable urban design. address amman, jordan tel. 00962779244849 e-mail: sh.rami83@aabu.edu.jo dr. safa al husban associate professor architecture engineering department, faculty of engineering, al al-bayt university, jordan main research area architectural design. address al mafraq, jordan tel. 00962772323043 e-mail: safaalhusban@aabu.edu.jo journal of sustainable architecture and civil engineering 2014/4/9 26 jsace 4/9 journal of sustainable architecture and civil engineering vol. 4 / no. 9 / 2014 pp. 26-34 doi 10.5755/j01.sace.9.4.7357 © kaunas university of technology received 2014/06/17 accepted after revision 2014/10/21 roundabouts as an effective tool of traffic management robert ziolkowski* bialystok university of technology, faculty of civil and environmental engineering wiejska st. 45e, 15-351 bialystok, poland *corresponding author: robert.ziolkowski@pb.edu.pl roundabouts as an effective tool of traffic management introduction driving speed is one of the most important factors in road safety and speed not only affects the severity of a crash, but is also related to the risk of being involved in a crash. inappropriate speed is responsible for more than a third of all fatal accidents occurring on roads. in poland every year majority of all traffic accidents occur in urban areas from which most is recorded at junctions and their vicinity. hence it is of great importance to effectively manage speed and enforce speed limits on existing road network. replacing already existing threeor four-arm junctions by roundabouts and construction new ones is considered to be a good solution for safety improvements and also are pointed to be within traffic calming features but their effectiveness is influencing by type, shape and geometry of the junction. the aim of this paper is to analyse the effectiveness of chosen traffic calming measures in comparison with the effectiveness of roundabouts. research area was located in city of bialystok, poland and included a group of commonly applied physical measures together with small and mini roundabouts. measurements of instantaneous speed by utilizing gps data logger and assessment of the extent impact of selected tcms on drivers’ manoeuvres were undertaken to develop the investigation. keywords: traffic safety, speed, roundabouts, traffic calming measures, influencing zone. traffic management is related to planning, coordinating, controlling and organizing traffic to achieve efficiency and effectiveness of the existing road capacity. this includes techniques and strategies that generally are used to mitigate congestion, minimize delays, ensure smooth, fast but safe and economically reasonable conditions for vehicular movement from one place to another and are intended to improve traffic safety for all road users. special attention in terms of traffic safety is given to speed management that emerges from the need to limit the negative effects of excessive and inappropriate speeds. both excessive speed (driving above the speed limits) and inappropriate speed (driving too fast for the prevailing conditions, but within the limits) are within a definition of speeding and are very dangerous and undesirable. speeding is being a causation factor in around one third of fatal accidents while speed is an aggravating factor in the severity of all accidents and more than two-thirds of these casualties occur at urban junctions. furthermore it has also serious consequences on the environment and energy consumption. hence arises the necessity of speed control and management. http://dx.doi.org/10.5755/j01.sace.9.4.7357 27 journal of sustainable architecture and civil engineering 2014/4/9 sped management can be defined as a set of measures to limit the negative effects of excessive and inappropriate speeds and incorporate a wide range of measures. special group that is distinguished within speed management creates traffic calming which is defined as the management of inappropriate vehicular speeds and volumes through educational, enforcement and engineering measures so that minimize their negative impacts on residents, pedestrians bicyclists and schools. traffic calming measures (tcms) are put in place on roads for the intention of slowing down or reducing motor-vehicle traffic to acceptable level as well as to improve safety for pedestrians and cyclists [o’flaherty 2006, guidelines 2006, mini roundabouts 2012]. the main objective underlying traffic calming are to: _ reduce the higher speeds of vehicles in the traffic stream(s), _ create road conditions which encourage motorists to drive carefully and calmly, _ remove extraneous car and commercial vehicle traffic from the road being calmed, _ improve amenity and enhance the environment, _ reduce accident numbers and severity however the key objective is that of reducing high vehicle speed. traffic calming schemes incorporate a wide range of measures although the effectiveness of this varies according to the measures employed. specific measures may be grouped into four categories [pennsylvania’s 2008]: _ vertical deflection (road humps, bumps, lumps and tables, cushions, rumble strips, raised crosswalks and intersections), _ horizontal deflection (curb-extension, chicane, gateway, raised median island, traffic circle), _ physical obstruction (semi and diagonal diverter, right-in and righ-out island, raised median through intersection, street closure), _ signs and pavement markings. educational and enforcement cannot be underestimated in creation drivers’ behaviour nevertheless engineering solutions related to changes of physical alignments of the street are most commonly used. within spot traffic restraints from among a number of currently available devices vertical shifts placed on streets are the most effective in speed reduction [ziolkowski and saleh 2013] but their effectiveness is reduced to a very short section hence particular attention should be given to their location. due to constraints limiting their usage those measures are mainly applied in residential streets in vicinity of places of a particular care due to the presence of children or where unprotected road users casualties are likely to occur. another solution aiming at traffic calming although not very often met in undeveloped countries due to relatively high implementing costs are area-wide schemes. through traffic is then removed from residential streets by implementing street closures or one-way systems or by establishing road streets hierarchy. opposite to calmed area main roads do not involve the use of vertical shifts and are improved in order to carry a larger traffic volume without additional delays or more accidents. those solutions reduce a number of traffic accidents more effectively in residential streets than on main roads. roundabout is type of circular intersection in which road traffic flows in one direction around a central island. according to [nchrp report 2000] there are three distinct types of circular intersections: _ rotaries – old-style circular intersections common to the united states prior to the 1960’s, characterized by a large diameter that typically results in travel speeds within the circulatory roadway that exceed 50 km/h (30 mph), roundabouts as a tool of traffic managem journal of sustainable architecture and civil engineering 2014/4/9 28 _ neighborhood traffic circles – typically built at the intersections of local streets for reasons of traffic calming and/or esthetics. the intersection approaches may be uncontrolled or stopcontrolled. _ roundabouts circular intersections with specific design and traffic control features. these features include yield control of all entering traffic, channelized approaches, and appropriate geometric curvature to ensure that travel speeds on the circulatory roadway are typically less than 50 km/h, _ signalized traffic circles are circular intersections where traffic signals are used to control one or more entry–circulating point. this solution is not very common due to different operational characteristics from yield-controlled roundabouts, with queue storage within the circulatory roadway and progression of signals required. according to polish standards [wytyczne 2001] roundabout is defined as a circulatory intersection with a one-way circular roadway around a curb central island for circulating traffic with a small exception given to mini roundabouts which offer most of the benefits of regular roundabouts but are characterized by a small diameter and traversable island. depending on the size of central island and inscribed circle diameter roundabouts are classified as: large, medium, small and mini. modern roundabouts require entering traffic to yield to traffic already in the circle and optimally observe various design rules to increase safety. they are used extensively worldwide to reduce accidents, traffic delays, fuel consumption, air pollution and construction costs, while increasing capacity and enhancing intersection beauty. they have been successfully used to control traffic speeds in residential neighborhoods and are accepted as one of the safest types of intersection design though study of safety in bialystok [ziolkowski 2013] have showed that roundabouts can be a place for a cumulative high number of collisions. considering roundabout as a mean of traffic calming they can be used in place of a traditional stop intersection or traffic signal. roundabouts require drivers to slow down to a speed that allows them to comfortably maneuver around the circle in a counterclockwise direction. the primary benefit of them is speed control and reduction in angle and turning collisions. from the safety point of view what matters is the number of collision points in a junction at which road users may possibly come into conflict with each other (fig. 1). the fewer the potential conflict points, the safer the junction is (fig. 1). another aspect is the vehicle passing speed which while passing a roundabout is relatively low. single-lane small and mini roundabouts are considered to be the safest in those terms. conventional roundabouts are appropriate for major collectors and arterials where they can reduce accidents and assist traffic flow. mini roundabouts should only be used on distributors and minor collectors within residential areas where they increase the intersection capacity and promote safety [mini roundabouts 2012]. effectiveness is reduced to a very short section hence particular attention should be given to their location. due to constraints limiting their usage those measures are mainly applied in residential streets in vicinity of places of a particular care due to the presence of children or where unprotected road users casualties are likely to occur. another solution aiming at traffic calming although not very often met in undeveloped countries due to relatively high implementing costs are area-wide schemes. through traffic is then removed from residential streets by implementing street closures or one-way systems or by establishing road streets hierarchy. opposite to calmed area main roads do not involve the use of vertical shifts and are improved in order to carry a larger traffic volume without additional delays or more accidents. those solutions reduce a number of traffic accidents more effectively in residential streets than on main roads. 2. roundabouts as a tool of traffic management roundabout is type of circular intersection in which road traffic flows in one direction around a central island. according to [nchrp report 2000] there are three distinct types of circular intersections: rotaries old-style circular intersections common to the united states prior to the 1960’s, characterized by a large diameter that typically results in travel speeds within the circulatory roadway that exceed 50 km/h (30 mph), neighborhood traffic circles – typically built at the intersections of local streets for reasons of traffic calming and/or esthetics. the intersection approaches may be uncontrolled or stop-controlled. roundabouts circular intersections with specific design and traffic control features. these features include yield control of all entering traffic, channelized approaches, and appropriate geometric curvature to ensure that travel speeds on the circulatory roadway are typically less than 50 km/h, signalized traffic circles are circular intersections where traffic signals are used to control one or more entry–circulating point. this solution is not very common due to different operational characteristics from yield-controlled roundabouts, with queue storage within the circulatory roadway and progression of signals required. according to polish standards [wytyczne 2001] roundabout is defined as a circulatory intersection with a one-way circular roadway around a curb central island for circulating traffic with a small exception given to mini roundabouts which offer most of the benefits of regular roundabouts but are characterized by a small diameter and traversable island. depending on the size of central island and inscribed circle diameter roundabouts are classified as: large, medium, small and mini. modern roundabouts require entering traffic to yield to traffic already in the circle and optimally observe various design rules to increase safety. they are used extensively worldwide to reduce accidents, traffic delays, fuel consumption, air pollution and construction costs, while increasing capacity and enhancing intersection beauty. they have been successfully used to control traffic speeds in residential neighborhoods and are accepted as one of the safest types of intersection design though study of safety in bialystok [ziolkowski 2013] have showed that roundabouts can be a place for a cumulative high number of collisions. considering roundabout as a mean of traffic calming they can be used in place of a traditional stop intersection or traffic signal. roundabouts require drivers to slow down to a speed that allows them to comfortably maneuver around the circle in a counterclockwise direction. the primary benefit of them is speed control and reduction in angle and turning collisions. from the safety point of view what matters is the number of collision points in a junction at which road users may possibly come into conflict with each other (fig. 1). the fewer the potential conflict points, the safer the junction is (fig. 1). another aspect is the vehicle passing speed which while passing a roundabout is relatively low. singlelane small and mini roundabouts are considered to be the safest in those terms. figure 1. conflict points on roundabout, t-junction and four-arm junction [mini roundabouts 2012]. conventional roundabouts are appropriate for major collectors and arterials where they can reduce accidents and assist traffic flow. mini roundabouts should only be used on distributors and minor collectors within residential areas where they increase the intersection capacity and promote safety [mini roundabouts 2012]. 3. sustainable traffic safety sustainability in general means that everything that we need for our survival and well-being depends, either directly or indirectly, on our natural environment [allen ..., 1980]. however when it comes to road infrastructure and traffic safety it is more appropriate to speak about sustainable development as “likely to achieve lasting satisfaction of human needs and improvement of the quality of human life” [sustainable safety 2010] and sustainable safety the approach to achieve and manage road safety. sustainable safety is based on five principles: functionality of roads, homogeneity of speed, predictability of roads, forgiveness of road/street environment and state awareness by the road users. the principles originally were based on scientific research and theories from traffic engineering, biomechanics and psychology but after first few years experiences they have been expanded and presently also include infrastructure, vehicles, intelligent transport system, education and enforcement of laws and regulations. in a sustainably safe traffic system the main objective is preventing severe crashes and eliminating severe injuries fig. 1 conflict points on roundabout, t-junction and four-arm junction [mini roundabouts 2012] 29 journal of sustainable architecture and civil engineering 2014/4/9 sustainable traffic safety problem of excessive speed in bialystok a) posted speed 70 km/h when crashes occur as much as possible and in instances where prevention is not yet possible, the probability of severe injury should be reduced to almost zero. roads and vehicles must be adapted to the human capabilities and the human has to be educated enough to be able to operate a vehicle on a road in a safe manner. in this terms highly dangerous in traffic remains large differences in speed and mass that the human being has to deal with so the fundamental is effective speed management. 3. problem of excessive speed in bialystok the problem of speeding drivers is widely common in poland in both rural roads and urban areas. polish experiences show that depending on the type of cross section the average percentage of drivers exceeding existing speed limits in rural roads ranges from 50 to over 70% while in cities this value ranges from 20 to 65%. the highest percentage of speeding drivers (up to 90%) was recorded on through roads in small towns [gaca et al. 2004]. in bialystok the number of speeding drivers is very troublesome and depends on road hierarchy, its function, geometry characteristics and posted speed limits. previous studies [ziolkowski 2012] have showed that the percentage of drivers exceeding speed limits vary from 32% (dual carriageway with speed limit of 70 km/h) to even 100% (single carriageway with a speed limit of 40km/h). the study has also revealed that in general non-intrusive administrative regulations as a tool of speed management are of low efficiency and traffic flow characterizes with a high heterogeneity (fig. 2) which is very unfavourable in terms of traffic safety/drivers’ behaviour. a) posted speed 70 km/h b) posted speed 50 km/h fig. 2. speed distribution in relation to type of a road and posted speed limit a) dual carriageway, b) single carriageway the need for more effective traffic management arises from low effectiveness of administrative tools and results in the common use of physical solutions of tcms such as: speed humps, cushions and raised pedestrian crossings, intersections or median islands. hence the aim of this paper was to compare the efficiency between the use of roundabouts with the use of physical features in terms of their influence on drivers’ violence maneuvers and speed homogeneity. 4. research area and methodology of data collection research area included mini and small roundabouts and chosen measures of traffic calming put in the streets located in bialystok. test drives were conducted in free flow driving conditions in order to avoid any disturbances arising from the presence of other road users. the summary characteristics of selected roundabouts are presented in table 1 and the view of two examples of analysed roundabouts are presented in fig. 3. the data was collected by utilizing gps data logger which allowed to monitor and record second-by-second in-field vehicle position and speed along tested sections. the vehicle’s speed and position was collected by a test car in 1s interval during peak-off hours. the test vehicle was a passenger car and the employed drivers were suggested to drive according to their natural driving patterns. as a result a number of individual speed profiles for test sections have been achieved. speed profiles with abnormal driving patterns were excluded from calculations of average speed profile. table 1. geometry characteristics of selected roundabouts type of roundabout geometry parameters central island diameter [m] inscribed circle diameter [m] circulatory roadway [m] small (s1) 21 34 4,25 small (s2) 19,5 35 5,5 small (s3) 24 40 4,8 mini (m_1) 4,5 15 5,5 mini (m_2) 10 21 5 a) b) b) posted speed 50 km/h when crashes occur as much as possible and in instances where prevention is not yet possible, the probability of severe injury should be reduced to almost zero. roads and vehicles must be adapted to the human capabilities and the human has to be educated enough to be able to operate a vehicle on a road in a safe manner. in this terms highly dangerous in traffic remains large differences in speed and mass that the human being has to deal with so the fundamental is effective speed management. 3. problem of excessive speed in bialystok the problem of speeding drivers is widely common in poland in both rural roads and urban areas. polish experiences show that depending on the type of cross section the average percentage of drivers exceeding existing speed limits in rural roads ranges from 50 to over 70% while in cities this value ranges from 20 to 65%. the highest percentage of speeding drivers (up to 90%) was recorded on through roads in small towns [gaca et al. 2004]. in bialystok the number of speeding drivers is very troublesome and depends on road hierarchy, its function, geometry characteristics and posted speed limits. previous studies [ziolkowski 2012] have showed that the percentage of drivers exceeding speed limits vary from 32% (dual carriageway with speed limit of 70 km/h) to even 100% (single carriageway with a speed limit of 40km/h). the study has also revealed that in general non-intrusive administrative regulations as a tool of speed management are of low efficiency and traffic flow characterizes with a high heterogeneity (fig. 2) which is very unfavourable in terms of traffic safety/drivers’ behaviour. a) posted speed 70 km/h b) posted speed 50 km/h fig. 2. speed distribution in relation to type of a road and posted speed limit a) dual carriageway, b) single carriageway the need for more effective traffic management arises from low effectiveness of administrative tools and results in the common use of physical solutions of tcms such as: speed humps, cushions and raised pedestrian crossings, intersections or median islands. hence the aim of this paper was to compare the efficiency between the use of roundabouts with the use of physical features in terms of their influence on drivers’ violence maneuvers and speed homogeneity. 4. research area and methodology of data collection research area included mini and small roundabouts and chosen measures of traffic calming put in the streets located in bialystok. test drives were conducted in free flow driving conditions in order to avoid any disturbances arising from the presence of other road users. the summary characteristics of selected roundabouts are presented in table 1 and the view of two examples of analysed roundabouts are presented in fig. 3. the data was collected by utilizing gps data logger which allowed to monitor and record second-by-second in-field vehicle position and speed along tested sections. the vehicle’s speed and position was collected by a test car in 1s interval during peak-off hours. the test vehicle was a passenger car and the employed drivers were suggested to drive according to their natural driving patterns. as a result a number of individual speed profiles for test sections have been achieved. speed profiles with abnormal driving patterns were excluded from calculations of average speed profile. table 1. geometry characteristics of selected roundabouts type of roundabout geometry parameters central island diameter [m] inscribed circle diameter [m] circulatory roadway [m] small (s1) 21 34 4,25 small (s2) 19,5 35 5,5 small (s3) 24 40 4,8 mini (m_1) 4,5 15 5,5 mini (m_2) 10 21 5 a) b) sustainability in general means that everything that we need for our survival and well-being depends, either directly or indirectly, on our natural environment [allen ..., 1980]. however when it comes to road infrastructure and traffic safety it is more appropriate to speak about sustainable development as “likely to achieve lasting satisfaction of human needs and improvement of the quality of human life” [sustainable safety 2010] and sustainable safety the approach to achieve and manage road safety. sustainable safety is based on five principles: functionality of roads, homogeneity of speed, predictability of roads, forgiveness of road/street environment and state awareness by the road users. the principles originally were based on scientific research and theories from traffic engineering, biomechanics and psychology but after first few years experiences they have been expanded and presently also include infrastructure, vehicles, intelligent transport system, education and enforcement of laws and regulations. in a sustainably safe traffic system the main objective is preventing severe crashes and eliminating severe injuries when crashes occur as much as possible and in instances where prevention is not yet possible, the probability of severe injury should be reduced to almost zero. roads and vehicles must be adapted to the human capabilities and the human has to be educated enough to be able to operate a vehicle on a road in a safe manner. in this terms highly dangerous in traffic remains large differences in speed and mass that the human being has to deal with so the fundamental is effective speed management. the problem of speeding drivers is widely common in poland in both rural roads and urban areas. polish experiences show that depending on the type of cross section the average percentage of drivers exceeding existing speed limits in rural roads ranges from 50 to over 70% while in cities this value ranges from 20 to 65%. the highest percentage of speeding drivers (up to 90%) was recorded on through roads in small towns [gaca et al. 2004]. in bialystok the number of speeding drivers is very troublesome and depends on road hierarchy, its function, geometry characteristics and posted speed limits. previous studies [ziolkowski 2012] have showed that the percentage of drivers exceeding speed limits vary from 32% (dual carriageway with speed limit of 70 km/h) to even 100% (single carriageway with a speed limit of 40km/h). the study has also revealed that in general nonintrusive administrative regulations as a tool of speed management are of low efficiency and traffic flow characterizes with a high heterogeneity (fig. 2) which is very unfavourable in terms of traffic safety/drivers’ behaviour. the need for more effective traffic management arises from low effectiveness of administrative1 tools and results in the common use of physical solutions of tcms such as: speed humps, cushions and raised pedestrian crossings, intersections or median islands. hence the aim of this paper was to compare the efficiency between the use of roundabouts with the use of physical features in terms of their influence on drivers’ violence maneuvers and speed homogeneity. fig. 2 speed distribution in relation to type of a road and posted speed limit a) dual carriageway, b) single carriageway journal of sustainable architecture and civil engineering 2014/4/9 30 research area included mini and small roundabouts and chosen measures of traffic calming put in the streets located in bialystok. test drives were conducted in free flow driving conditions in order to avoid any disturbances arising from the presence of other road users. the summary characteristics of selected roundabouts are presented in table 1 and the view of two examples of analysed roundabouts are presented in fig. 3. the data was collected by utilizing gps data logger which allowed to monitor and record second-by-second in-field vehicle position and speed along tested sections. the vehicle’s speed and position was collected by a test car in 1s interval during peakoff hours. the test vehicle was a passenger car and the employed drivers were suggested to drive according to their natural driving patterns. as a result a number of individual speed profiles for test sections have been achieved. speed profiles with abnormal driving patterns were excluded from calculations of average speed profile. research area and methodology of data collection results and analyses a) b) fig. 3. roundabouts subject to analysis a)mini roundabout m_1, b) small roundabout s_2 5. results and analyses as a result a number of individual speed profiles were achieved (fig. 4a) based on which average individual speed profiles were developed (fig. 4b). using these profiles drivers’ behaviour in vicinity of roundabouts and selected tcms were developed by assessing the influencing zones and speed differences between the beginning point set at the latest position where the vehicle’s speed remained at a constant level in approach section and the end point set at a point where vehicle reached the lowest speed (fig. 3b). end points were located before the yield line at the entrance in case of roundabouts and over a placement of a specific tcm. to evaluate traffic homogeneity in vicinity of traffic calming measures speed distribution charts were elaborated and are presented in fig. 5 and 6. a) b) fig. 4. individual speed profiles in vicinity of a selected tcm a) summary chart, b) average speed chart a summary of the characteristics of key speed parameters produced in vicinity of tcms are provided in table 2 and they present differentiated impact of analysed tcms on average spot speed. table 2. key speed parameters for analysed street sections. street mean speed v m [km/h] standard deviation v 85 v 15 [km/h] type of calming measure tuwima 19,4 1,53 4,2 raised junction pułaskiego 21,8 3,85 9 raised pedestrian crossing wschodni a 21,1 3,88 6,9 rounded speed bumps kruczkow skiego 17,7 3,05 7,1 flat speed bump kruczkow skiego 20,0 3,14 6,6 rounded speed bump brzechwy 29,1 9,8 22,1 speed cushion pogodna 58,3 8,96 17,2 raised median island the lowest average speed v m =17.7 km/h is recorded for flat speed bump while the highest value v r =58.3 km/h is registered for raised median island. hardly no differences can be seen between mean speed values recorded in vicinity of varied vertical deflections and the difference between the lowest and the highest values is only 4.1 km/h. the presence of raised median island has no distinct influence on average speed when compare to an average speed on a similar section without such a feature. the difference does not exceed a value of 3 km/h. the shape of a speed bump does not seem to substantially influence on drivers and the difference is only 2.3 km/h with almost the same standard deviation. results provided in table 2 show that the presence of speed cushion positively affects drivers who in its vicinity slow down but not as much as in vicinity of vertical shifts were mean speed value is lower by about 31%. on the other hand not all of the drivers passing through the cushion are slowing down equally which results in high speed variations and unfavourably high diversity (v 85 -v 15 =22.1 km/h). presented data shows that high heterogeneity is also characteristic around raised median island (v 85 -v 15 =17.2 km/h). in vicinity of vertical shifts the a) b) fig. 3. roundabouts subject to analysis a)mini roundabout m_1, b) small roundabout s_2 5. results and analyses as a result a number of individual speed profiles were achieved (fig. 4a) based on which average individual speed profiles were developed (fig. 4b). using these profiles drivers’ behaviour in vicinity of roundabouts and selected tcms were developed by assessing the influencing zones and speed differences between the beginning point set at the latest position where the vehicle’s speed remained at a constant level in approach section and the end point set at a point where vehicle reached the lowest speed (fig. 3b). end points were located before the yield line at the entrance in case of roundabouts and over a placement of a specific tcm. to evaluate traffic homogeneity in vicinity of traffic calming measures speed distribution charts were elaborated and are presented in fig. 5 and 6. a) b) fig. 4. individual speed profiles in vicinity of a selected tcm a) summary chart, b) average speed chart a summary of the characteristics of key speed parameters produced in vicinity of tcms are provided in table 2 and they present differentiated impact of analysed tcms on average spot speed. table 2. key speed parameters for analysed street sections. street mean speed v m [km/h] standard deviation v 85 v 15 [km/h] type of calming measure tuwima 19,4 1,53 4,2 raised junction pułaskiego 21,8 3,85 9 raised pedestrian crossing wschodni a 21,1 3,88 6,9 rounded speed bumps kruczkow skiego 17,7 3,05 7,1 flat speed bump kruczkow skiego 20,0 3,14 6,6 rounded speed bump brzechwy 29,1 9,8 22,1 speed cushion pogodna 58,3 8,96 17,2 raised median island the lowest average speed v m =17.7 km/h is recorded for flat speed bump while the highest value v r =58.3 km/h is registered for raised median island. hardly no differences can be seen between mean speed values recorded in vicinity of varied vertical deflections and the difference between the lowest and the highest values is only 4.1 km/h. the presence of raised median island has no distinct influence on average speed when compare to an average speed on a similar section without such a feature. the difference does not exceed a value of 3 km/h. the shape of a speed bump does not seem to substantially influence on drivers and the difference is only 2.3 km/h with almost the same standard deviation. results provided in table 2 show that the presence of speed cushion positively affects drivers who in its vicinity slow down but not as much as in vicinity of vertical shifts were mean speed value is lower by about 31%. on the other hand not all of the drivers passing through the cushion are slowing down equally which results in high speed variations and unfavourably high diversity (v 85 -v 15 =22.1 km/h). presented data shows that high heterogeneity is also characteristic around raised median island (v 85 -v 15 =17.2 km/h). in vicinity of vertical shifts the as a result a number of individual speed profiles were achieved (fig. 4a) based on which average individual speed profiles were developed (fig. 4b). using these profiles drivers’ behaviour in vicinity of roundabouts and selected tcms were developed by assessing the influencing zones and speed differences between the beginning point set at the latest position where the vehicle’s speed remained at a constant level in approach section and the end point set at a point where vehicle reached the lowest speed (fig. 3b). end points were located before the yield line at the entrance in case of roundabouts and over a placement of a specific tcm. to evaluate traffic homogeneity in vicinity of traffic calming measures speed distribution charts were elaborated and are presented in fig. 5 and 6. a summary of the characteristics of key speed parameters produced in vicinity of tcms are provided in table 2 and they present differentiated impact of analysed tcms on average spot speed. the lowest average speed v m =17.7 km/h is recorded for flat speed bump while the highest value type of roundabout geometry parameters central island diameter [m] inscribed circle diameter [m] circulatory roadway [m] small (s1) 21 34 4,25 small (s2) 19,5 35 5,5 small (s3) 24 40 4,8 mini (m_1) 4,5 15 5,5 mini (m_2) 10 21 5 table 1 geometry characteristics of selected roundabouts a) b) fig. 3 roundabouts subject to analysis a)mini roundabout m_1, b) small roundabout s_2 31 journal of sustainable architecture and civil engineering 2014/4/9 v r =58.3 km/h is registered for raised median island. hardly no differences can be seen between mean speed values recorded in vicinity of varied vertical deflections and the difference between the lowest and the highest values is only 4.1 km/h. the presence of raised median island has no distinct influence on average speed when compare to an average speed on a similar section without such a feature. the difference does not exceed a value of 3 km/h. the shape of a speed bump does not seem to substantially influence on drivers and the difference is only 2.3 km/h with almost the same standard deviation. results provided in table 2 show that the presence of speed cushion positively affects drivers who in its vicinity slow down but not as much as in vicinity of vertical shifts were mean speed value is lower by about 31%. on the other hand not all of the drivers passing through the cushion are slowing down equally which results in high speed variations and unfavourably high diversity (v 85 -v 15 =22.1 km/h). presented data shows that high heterogeneity is also characteristic around raised median island (v 85 -v 15 =17.2 km/h). in vicinity of vertical shifts the speed variations is much lower and do not exceed 9 km/h. the most favourable situation in this terms is observed in case of raised junction where v 85 -v 15 =4.2 km/h. figures 5 and 6 present charts of speed distributions in vicinity of chosen physical traffic calming measures. considering influencing zones in nearness of tcms the largest extent is achieved for raised junction where average deceleration distance is 105 m and the shortest average braking distance (52 m) is for raised median island. street mean speed v m [km/h] standard deviation v 85 v 15 [km/h] type of calming measure tuwima 19,4 1,53 4,2 raised junction pułaskiego 21,8 3,85 9 raised pedestrian crossing wschodnia 21,1 3,88 6,9 rounded speed bumps kruczkow skiego 17,7 3,05 7,1 flat speed bump kruczkowskiego 20,0 3,14 6,6 rounded speed bump brzechwy 29,1 9,8 22,1 speed cushion pogodna 58,3 8,96 17,2 raised median island a) b) table 2 key speed parameters for analysed street sections fig. 4 individual speed profiles in vicinity of a selected tcm a) summary chart, b) average speed chart journal of sustainable architecture and civil engineering 2014/4/9 32 analysing the effectiveness of roundabouts as a calming tool in terms of their affecting the average speed it emerges from fig. 6 that the presence of these junctions essentially decrease vehicular speed and this influence depends on the type and size of roundabout. average speed before roundabout influencing zone (v b ) is clearly related to the size of roundabout and decreases with the decrease in size of island diameter. on average, for small roundabouts v b =43.34 km/h and is higher than v b recorded in vicinity of mini roundabouts (v b =30.91 km/h). similar relationship is evident in terms of speed on circulatory roadway (v r ). average vehicular speed registered for small roundabout v r =22.7 km/h is about 34% higher than average v r for mini roundabouts (14.9 km/h) recorded for mini roundabouts. the size of small roundabouts’ central island diameters, opposite to mini roundabouts, do not seem to affect distinctly on speed on circulatory roadway. the difference between maximum and minimum value of v r within small roundabouts is 3.57 km/h while between mini roundabouts that difference is much higher and results in a value of 8.58 km/h. in terms of speed reduction, as a result of roundabout presence, an average value (v b -v r ) for small roundabouts is 20,67 km/h and is about 25% higher in comparison with speed reduction in vicinity of mini roundabouts. that difference can be explained by the geometry characteristics and horizontal alignment of adjacent streets which prevent drivers from speeding. considering the influence of type of roundabout on drivers braking decision small roundabouts have a greater impact on drivers in comparison fig. 5 distribution of instantaneous speed in vicinity of a) flat speed bump and b) rounded speed bump fig. 6 distribution of instantaneous speed along a) raised median island and b) speed cushion b) a) b) a) 33 journal of sustainable architecture and civil engineering 2014/4/9 with mini roundabouts. drivers that approach the intersection start to slow down from an average distance of 115 m from small roundabouts and 88 m from mini roundabouts. however these values differ a lot depending on the type of roundabout and within a group of small roundabouts the achieved values of braking distance range from 59 m to 192 m. within mini roundabouts these values range from 51 m to 117 m. b) fig. 5. distribution of instantaneous speed in vicinity of a) flat speed bump and b) rounded speed bump a) b) fig. 6. distribution of instantaneous speed along a) raised median island and b) speed cushion considering influencing zones in nearness of tcms the largest extent is achieved for raised junction where average deceleration distance is 105 m and the shortest average braking distance (52 m) is for raised median island. fig. 7. average speed in vicinity of roundabouts depending on the type of junction analysing the effectiveness of roundabouts as a calming tool in terms of their affecting the average speed it emerges from fig. 6 that the presence of these junctions essentially decrease vehicular speed and this influence depends on the type and size of roundabout. average speed before roundabout influencing zone (v b ) is clearly related to the size of roundabout and decreases with the decrease in size of island diameter. on average, for small roundabouts v b =43.34 km/h and is higher than v b recorded in vicinity of mini roundabouts (v b =30.91 km/h). similar relationship is evident in terms of speed on circulatory roadway (v r ). average vehicular speed registered for small roundabout v r =22.7 km/h is about 34% higher than average v r for mini roundabouts (14.9 km/h) recorded for mini roundabouts. the size of small roundabouts’ central island diameters, opposite to mini roundabouts, do not seem to affect distinctly on speed on circulatory roadway. the difference between maximum and minimum value of v r within small roundabouts is 3.57 km/h while between mini roundabouts that difference is much higher and results in a value of 8.58 km/h. in terms of speed reduction, as a result of roundabout presence, an average value (v b -v r ) for small roundabouts is 20,67 km/h and is about 25% higher in comparison with speed reduction in vicinity of mini roundabouts. that difference can be explained by the geometry characteristics and horizontal alignment of adjacent streets which prevent drivers from speeding. considering the influence of type of roundabout on drivers braking decision small roundabouts have a greater impact on drivers in comparison with mini roundabouts. drivers that approach the intersection start to slow down from an average distance of 115 m from small roundabouts and 88 m from mini roundabouts. however these values differ a lot depending on the type of roundabout and within a group of small roundabouts the achieved values of braking distance range from 59 m to 192 m. within mini roundabouts these values range from 51 m to 117 m. 6. conclusions this study evaluated the impact of small and mini roundabouts on vehicle’s speed in comparison with the impact of chosen traffic calming measures. conducted measurements of instantaneous speed were employed to evaluate the effectiveness of roundabouts as a tool of traffic management in terms of speed reduction in comparison with typically installed traffic calming measures. overall, it was found that the presence of roundabouts influence drivers’ speed and behaviour depending on the type and size of a roundabout. fig. 7 average speed in vicinity of roundabouts depending on the type of junction this study evaluated the impact of small and mini roundabouts on vehicle’s speed in comparison with the impact of chosen traffic calming measures. conducted measurements of instantaneous speed were employed to evaluate the effectiveness of roundabouts as a tool of traffic management in terms of speed reduction in comparison with typically installed traffic calming measures. overall, it was found that the presence of roundabouts influence drivers’ speed and behaviour depending on the type and size of a roundabout. the presence of roundabouts positively decreases the average vehicle’s speed. mini roundabouts in this terms are more effective and average passing speed is lower by 34% as compared to the average speed in vicinity of small roundabouts. on the other hand it must be noticed that high heterogeneity of obtained results within mini roundabouts shows the need for further investigations in this scope on a wilder scale. comparing the influence of roundabouts on average passing speed with such an influence of chosen tcms vertical deflections such as speed bumps and raides intersections prove to be most effective measures in speed spot reduction. however considering the driving style it must be emphasized that for drivers it is very important to drive smoothly without the necessity of violent speed reduction. in this light the use of small and mini roundabouts is reasonable. the current study evaluated also high variety of results in terms of braking distance within small roundabouts. some ambiguous results within analysed roundabouts reveal and highlight the need for in-depth research in terms of assessing the severity of maneuvers and range of the influence zone of specific tcms and roundabouts. based on that it will be possible to evaluate more firm and clear conclusions especially within groups of roundabouts regarding design suggestions for specific purposes. conclusions allen r.: how to save the world. barnes noble books, 1980. gaca. s.; jamroz. k.; ząbczyk. k. 2004. system monitorowania zachowań kierujących pojazdami w polsce [monitoring system of drivers’ behaviour]. vi konferencja bezpieczeństwa ruchu drogowego, zegrze 2004. guidelines for traffic calming, i.m.e.s.a. municipal guidelines, edition mg2, durban 2006. mini roundabouts, good practice guidance. county surveyors society, department for transport, 2012. referencesnchrp report. roundabouts: an informational guide. second edition. transportation research board, us department of transportation federal highway administration, fhwa-rd-00-067, 2000. o’flaherty c.: “transport planning and traffic engineering”, elsevier 2006. pennsylvania’s trafffic calming handbook, publication no. 383 january 2001. sustainable safety: principles, misconceptions, and relations with other visions. svow institute for road safety research, leidschendam, 2010 journal of sustainable architecture and civil engineering 2014/4/9 34 traffic calming guidebook, borough of state college, 2008. wytyczne projektowania skrzyżowań drogowych. część ii – ronda [guidebook for junction design. part ii roundabouts]. gddkia, warszawa 2001. ziolkowski r., saleh w.: traffic calming measures: technically efficient to achieve their goals?, 6th international symposium on travel demand management, dalian 2013. ziolkowski, r.: wpływ środków uspokojenia ruchu na prędkość pojazdów w warunkach miejskich [influence of traffic calming measures on speed in cities], przeglad komunikacyjny, 2012 (4): 24-30. ziolkowski, r.: analiza bezpieczeństwa ruchu drogowego na wybranych skrzyżowaniach w białymstoku [analyses of traffic safety on chosen junctions in bialystok], przeglad komunikacyjny, 2013 (8): 18-21. ziolkowski, r.: analiza funkcjonowania obwodnicy śródmiejskiej w białymstoku [functional analyses of city bypass in bialystok], magazyn autostrady [highway magazin], 2014, nr 1-2. about the author robert ziolkowski lector, researcher bialystok university of technology, department of road engineering main research area traffic engineering, speed management, its address wiejska st. 45e, 15-351 bialystok, poland tel. +48 797 995 989 e-mail: robert.ziolkowski@pb.edu.pl journal of sustainable architecture and civil engineering 2021/2/29 62 *corresponding author: dtsirigo@civil.auth.gr energy and aesthetic upgrading interventions: assessing urban block renovation scenarios received 2021/05/26 accepted after revision 2021/09/02 journal of sustainable architecture and civil engineering vol. 2 / no. 29 / 2021 pp. 62-82 doi 10.5755/j01.sace.29.2.29176 energy and aesthetic upgrading interventions: assessing urban block renovation scenarios jsace 2/29 http://dx.doi.org/10.5755/j01.sace.29.2.29176 dimitra tsirigoti*, dimitrios zenginis, dimitrios bikas aristotle university of thessaloniki, faculty of engineering, department of civil engineering, laboratory of building construction and building physics, po box 429, 54124 thessaloniki, greece introduction the target towards carbon neutral cities emerges as a new way to mitigate the environmental pollution and the indisputable climate change, but it can also be the chance for the overall improvement of the quality of life by promoting the upgrading of the often low aesthetic quality of the urban environments. the objective of the research is to investigate renovation strategies at the city scale that will not only reduce the energy demand, but they will also promote the improvement of the city’s aesthetics. two different typologies of urban block forms of the greek city are examined, and four scenarios of renovation interventions are analysed according to energy and aesthetic criteria. the heating and cooling load demand is calculated through simulations for the four renovation scenarios which include: _ the improvement of the thermal insulation of the building’s shells. _ the use of phase change materials. _ the construction of green roofs. _ the integration of passive solar and shading systems. the findings of the research prove that the energy interventions at the urban block scale can define the degree of efficiency in the energy performance level without compromising aesthetics, as the added value resulting from higher aesthetics is a basic criterion for the overall improvement of the quality of life. keywords: energy efficiency, urban block form, energy renovation, city aesthetics, pcm, green roof, passive solar systems. sustainable urban development has been a major target during the last decades. as cities are complex systems, their sustainability depends on the development in multiple levels. therefore, different approaches have been proposed towards a sustainable urban development. among these approaches and strategies are the examination of sustainable urban forms, the implementation of sustainable transportation, the integration of renewable energy in the urban environment, the promotion of recycling, the waste and water management etc. at the same time the institutional framework in many countries has also been targeted in promoting the sustainability of the urban environments, especially in the building sector where the majority of countries have set stricter building codes fostering energy efficiency following the recast european directive 2010/31/eu on the energy performance of buildings (van oorschot, hofman, and halman 2016) and directive 2012/27/eu on energy efficiency (european union 63 journal of sustainable architecture and civil engineering 2021/2/29 2012). the institutional framework for the energy efficiency of buildings is also recently being reformed under the recommendation 2016/1318 of the european commission (european union commission 2016) for the promotion of nearly zero energy buildings and the revised energy performance of buildings directive 2018/844 (epbd 2018). the eu aims to be climate neutral until 2050 by proposing a european climate law to turn this political commitment into a legal obligation (a european green deal | european commission n.d.). under this direction, there have been many efforts to upgrade the existing building stock as there is a large amount of buildings which has been built in the past with low energy efficiency standards. on 14 october 2020 the commission published a new strategy for renovation called “a renovation wave for europe – greening our buildings, creating jobs, improving lives” (com(2020)662) (renovation wave | energy n.d.). moreover, there is a broad research for tools, strategies and campaigns for existing buildings targeting to a zero energy development (r2cities: residential renovation towards nearly zero energy cities n.d.), (renovate europe n.d.), climate neutral cities (clue n.d.) or innovative renovation strategies for building facades (tsikaloudaki et al. 2019). in addition, except from the energy efficiency, other aspects of building renovation are often considered for the existing buildings stock. low construction quality and low aesthetics are often apparent in low energy efficient buildings. in most european cities there is a large amount of building stock both in the central areas and in the periphery of large cities which has been built in previous decades which has not been maintained properly for a longtime and in most cases, it cannot meet the contemporary needs in terms of quality of life, energy efficiency, economic viability and environmental protection (robust and reliable technology concepts and business models for triggering deep renovation of residential buildings in eu | 4rineu project | h2020 | cordis | european commission n.d.). apparently, a sustainable approach should target at an integrated renovation of existing buildings as, on the one hand, the majority of city centers have already been built and on the other hand, a new building replacing a demolished one would need many years to counterbalance the embodied energy loss from the demolition (craun 2012). the evaluation of the building stock has been a challenging issue during the past few years. there is a broad research focusing on the energy consumption of the residential building stock (sabunas and kanapickas 2017) and on the investigation of renovation interventions of single family houses taking into account the target for nearly zero energy buildings (nzeb) (serghides et al. 2015), or in apartment buildings, including scenarios for green roofs (karteris et al. 2016) or sunspaces (fotopoulou et al. 2018). many investigators have been trying to develop methods for evaluating the existing building stock of cities through the definition of building typologies (aksoezen et al. 2015), building archetypes (mata, sasic kalagasidis, and johnsson 2014), (caputo, costa, and ferrari 2013), urban block typologies (tsirigoti and tsikaloudaki 2018). other researches have proposed methodologies for defining retrofit strategies with the aid of data-driven approaches (ali et al. 2020) or other statistical methods (fracastoro and serraino 2011) in order to reduce the complexity of the urban tissue and the large number of building typologies of cities. among the various characteristics used in order to categorize the building stock is the age and the construction type of buildings, the building height, the surface to volume ratio, the floor area ratio (far) and other geometry factors such as road width, height to width ratio (h/w), plan proportions etc. several studies focus on all periods of construction including heritage (energy renovation of heritage buildings | interreg europe n.d.) or listed buildings, while others mainly focus on the non-protected building stock. retrofit strategies include building shell interventions in order to reduce the heat flow through journal of sustainable architecture and civil engineering 2021/2/29 64 the building elements or more advanced interventions including lighting and heating system replacement, renewable energy sources (res) installations or even more innovative or hybrid technologies. in the first category the most common method used is the thermal insulation of the buildings’ exterior surfaces. the renovation strategies could target on both the horizontal and vertical exterior surfaces, but the most common technology used is the addition of exterior thermal insulation composite systems (etics) in building facades and roofs. concerning the energy renovation of facades, except from the conventional type of etics, there are also passive techniques in order to increase solar heat gains and the addition of shading for reducing cooling load. the addition of attached sunspaces is the most commonly used passive solar technology in building renovation, followed by the construction of double skin facades. green facades have also been applied in many cases in order to improve the energy efficiency of buildings and to provide a new greener aesthetic in cities. green roof construction in existing buildings has also been examined as an energy upgrade renovation strategy of the building shell which can at the same time reduce heating and cooling load and improve the urban microclimate of cities. a more innovative energy renovation technology of the building shell has been the use of phase change materials (pcm) which could increase the building’s thermal mass without adding significant weight to the construction. in existing buildings not all interventions that can be used in new buildings are applicable, because it is not always easy to integrate all systems in existing structures due to structural or constructional barriers. in the second category there are several kinds of installations of more efficient hvac systems with fuels with less pollutant emissions, and several types of renewable energy sources systems, such as photovoltaics, ground source heat pumps (gshp) etc. there are also hybrid systems combining both approaches to maximize the efficiency of the interventions and to provide an integrated method for retrofitting buildings (aesthetic, lighting, energy, acoustics etc.) (e2vent h2020 project n.d.), (ferrante et al. 2019). most of the hybrid approaches target on specific energy rating or even on nearly zero energy buildings. these technologies and strategies are mainly targeted to the renovation of individual buildings resulting in a fragmented renovation of the building stock. this leads to a low impact of the renovation efforts on the overall city and on the inability to plan a wide scale renovation strategy at the city scale. another issue resulting from this fragmented renovation is the low aesthetics of the city. on the one hand, there is no uniform renovation vision and each building is renovated without taking into account the condition of neighboring buildings and the overall image of the city and, on the other hand, the different strategies of renovation designed in adjacent buildings create an even larger uniformity on the appearance of the façades. this is why there have been efforts to apply renovation strategies in a larger scale (mastrucci et al. 2014), (serrano-jimenez, barrios-padura, and molina-huelva 2017), (rovers, n.d.) in order to improve the overall quality of the building stock at urban scale and to design renovation in a more sustainable way in terms of promoting at the same time energy efficiency, quality of life, aesthetic quality and economy of scale. the form and the energy profile of the greek building stock the greek city consists of a variety of building forms according to the period of construction, the distance from the city center and the building use. in most cases the central areas present higher 65 journal of sustainable architecture and civil engineering 2021/2/29 densities than more distant areas and the buildings form a continuous urban tissue as they are attached to each other. on the other hand, urban tissues appear to be more discontinuous in the periphery of city centers, while building heights remain relatively high in both cases. in even more distant areas, the urban tissue has lower building heights and lower density. except from the form of historic buildings, most building forms which have been built after the 50’s have been largely defined by the building regulations’ restrictions and rules. the multifamily apartment building, which is the most common building type met in the greek city after the 50’s, can be easily analysed by examining the regulatory limitations and restrictions of each period. even though the architectural form of the city can significantly vary, many building types follow common rules of form and geometry. the apartment buildings are characterized by typical floor plans. the ground floor has either a larger height when it has a commercial use, or it is elevated from the ground by 1.5 m when it houses an apartment. as a result of the typical floor plan, the facades also present a typical distribution of openings which is repeated in all typical floors. finally, balconies have also typical form and dimensions in all floors. this means that the form of the greek city in its best or worst architecture is characterized by a kind of uniformity resulting from the square urban grid and the dominant building type which has been developed as a result of a series of building regulations. as there are very few unbuilt spaces in the city centers, and the majority of existing buildings have been built between 1950 and 1980 it can be easily concluded that the construction of these buildings cannot meet the contemporary qualitative requirements in order to cover users’ needs and contemporary criteria of quality. the main constructional system of these buildings is reinforced concrete load bearing structure and double brick masonry walls. as far as it concerns energy consumption most of these buildings present low performance as they have been built during periods where thermal insulation of the building shell was mandatory or even in earlier periods when the contemporary thermal insulation materials were unknown. in addition, the overall construction and aesthetic quality remains low due to the fact that all interventions that have been made on the buildings since their original construction have been implemented in a random and arbitrary way without any central planning or design concept. these, interventions can be grouped into two main categories: first, several building elements have been added on building facades over the years, such as window shutters, shading overhangs, mechanical equipment for heating, cooling and hot water etc. second, old and degraded materials and building elements have not been replaced since their original construction or they have spontaneously been replaced in some apartments by the owners while in others they remain in their original form. broken shading overhangs, eroded railings, or partially damaged façade claddings or exterior coatings on building facades define the appearance of many greek buildings. as it can be easily concluded, the built environment of the greek city faces issues of degradation due to three main factors: low construction quality, low energy performance and low aesthetic quality. the lack of renovation for many years has led to the emergent need for a renovation strategy that will promote the improvement of these three parameters at the same time in order to upgrade the quality of the built environment in the greek city. during the past decade the greek state has promoted some efforts to improve one of these three parameters -the energy performance of these buildingsmainly through economic incentives, which were imposed in order to comply with the european directives for the energy performance of buildings. all efforts intended to improve only the energy performance of buildings without considering any other aspects of improvement of the overall quality of buildings and especially their aesthetic quality. on the contrary, many of these interventions contributed to a further degradation of the aesthetic and construction quality of the buildings. journal of sustainable architecture and civil engineering 2021/2/29 66 the effort to improve the energy performance of buildings in greece begun in 2008 with the funding for the replacement of old air conditioning installations in residencies. split unit systems were replaced by new ones in the same random positions as the old ones. the installation of solar thermal collectors for domestic hot water became more and more common on the rooftops of private houses or apartment buildings which were also promoted by state funding. subsidies for the installation of domestic photovoltaics were also promoted by the state to promote res. solar thermal collectors or photovoltaics were installed on flat or inclined roofs in a random way. the promotion of replacement of existing central oil-based heating systems with natural gas local heating systems followed the same irrational positioning of the natural gas units on the buildings facades as well. in 2010, after the implementation of the national regulation for the energy performance of buildings (kenak) (greek regulation for the energy performance of buildings, fek 2367 2017), followed several programs with subsidies for upgrading the energy performance of buildings which among others included building shell thermal insulation interventions, shading systems installation or replacement of older ones. in 2011 the “energy saving in the housing sector program i” was launched and in 2018 and in 2019 followed the “energy saving in the housing sector program ii”. recently, the “energy saving and energy autonomy in the housing sector” has been announced. all these interventions, repeated in almost all buildings, resulted in even lower aesthetic image of the city, which in addition the degradation of many other elements of the facades such as railings, awnings and window casements have led to a crucial question for the future interventions targeting to the improvement of the energy performance of buildings. scope and objective the scope of the research is to investigate smart renovation strategies at the city scale which can contribute at the same time on the limitation of carbon gas emissions, the improvement of the city’s aesthetics and the improvement of the overall quality of the city. the three main objectives of the research are: a. to prove that a sustainable energy performance renovation strategy could be more efficient if implemented at the urban block scale instead of the building scale, as it can provide added value on the aesthetics and building construction quality. b. to investigate ways for the design and implementation of energy upgrading strategies on urban blocks. c. to assess and compare the energy savings of the proposed renovation strategies. the basic research question is if the tools targeted to the future energy performance improvement of buildings could also be used as a challenge to improve the overall quality of the buildings, taking into account the aesthetic parameter and the improvement of not only energy efficiency but also of the overall quality of construction. the research intends to propose ways of transforming the energy improvement of buildings into a challenge for the holistic regeneration of the cities’ overall quality. for the scope of the study, two typical urban blocks with different form and geometry are analyzed in order implement well known energy improvement strategies which can as well promote the aesthetic upgrading of the buildings. the research intends to prove that aesthetic and energy improvement strategies and technologies, applied not in individual buildings but in urban blocks, can be combined in order to promote an integrated regeneration of the city’s quality. the recent recast energy performance regulation and the economic incentives it can provide to the owners if used for the design and implementation of interventions at the urban block scale can provide the opportunity for a holistic regeneration of the greek cities. 67 journal of sustainable architecture and civil engineering 2021/2/29 description of the analysed cases as mentioned above, two models of typical urban blocks are analysed in order to implement several renovation strategies and to compare their efficiency according to form and geometry factors. the first urban block is of discontinuous form, meaning that buildings are detached, while the second urban block is of continuous form, with buildings attached to the neighboring buildings in both their sides. the plans and 3d drawings of the two examined urban bocks are presented in fig. 1 and fig. 2, while parameters of geometry and size are presented in table 1. methods ub plot surface (m2) exposed shell (m2) volume (m3) road width (m) height (m) n. of floors coverage ratio floor area ratio surface to volume (s/v) 1 d 3608 8965 17271 10 13 4 0.4 1.4 0.5 2 c 6864 33835 102391 10 22 7 0.7 4.7 0.3 table 1 description of geometry parameters of the two examined urban blocks overall quality of construction. the research intends to propose ways of transforming the energy improvement of buildings into a challenge for the holistic regeneration of the cities’ overall quality. for the scope of the study, two typical urban blocks with different form and geometry are analyzed in order implement well known energy improvement strategies which can as well promote the aesthetic upgrading of the buildings. the research intends to prove that aesthetic and energy improvement strategies and technologies, applied not in individual buildings but in urban blocks, can be combined in order to promote an integrated regeneration of the city’s quality. the recent recast energy performance regulation and the economic incentives it can provide to the owners if used for the design and implementation of interventions at the urban block scale can provide the opportunity for a holistic regeneration of the greek cities. methods 2.1. description of the analysed cases as mentioned above, two models of typical urban blocks are analysed in order to implement several renovation strategies and to compare their efficiency according to form and geometry factors. the first urban block is of discontinuous form, meaning that buildings are detached, while the second urban block is of continuous form, with buildings attached to the neighboring buildings in both their sides. the plans and 3d drawings of the two examined urban bocks are presented in fig. 1 and fig. 2, while parameters of geometry and size are presented in table 1. fig. 1. 3d representation drawing and plan of urban block typology 1 fig. 2. 3d representation drawing and plan of urban block typology 2 table 1. description of geometry parameters of the two examined urban blocks overall quality of construction. the research intends to propose ways of transforming the energy improvement of buildings into a challenge for the holistic regeneration of the cities’ overall quality. for the scope of the study, two typical urban blocks with different form and geometry are analyzed in order implement well known energy improvement strategies which can as well promote the aesthetic upgrading of the buildings. the research intends to prove that aesthetic and energy improvement strategies and technologies, applied not in individual buildings but in urban blocks, can be combined in order to promote an integrated regeneration of the city’s quality. the recent recast energy performance regulation and the economic incentives it can provide to the owners if used for the design and implementation of interventions at the urban block scale can provide the opportunity for a holistic regeneration of the greek cities. methods 2.1. description of the analysed cases as mentioned above, two models of typical urban blocks are analysed in order to implement several renovation strategies and to compare their efficiency according to form and geometry factors. the first urban block is of discontinuous form, meaning that buildings are detached, while the second urban block is of continuous form, with buildings attached to the neighboring buildings in both their sides. the plans and 3d drawings of the two examined urban bocks are presented in fig. 1 and fig. 2, while parameters of geometry and size are presented in table 1. fig. 1. 3d representation drawing and plan of urban block typology 1 fig. 2. 3d representation drawing and plan of urban block typology 2 table 1. description of geometry parameters of the two examined urban blocks overall quality of construction. the research intends to propose ways of transforming the energy improvement of buildings into a challenge for the holistic regeneration of the cities’ overall quality. for the scope of the study, two typical urban blocks with different form and geometry are analyzed in order implement well known energy improvement strategies which can as well promote the aesthetic upgrading of the buildings. the research intends to prove that aesthetic and energy improvement strategies and technologies, applied not in individual buildings but in urban blocks, can be combined in order to promote an integrated regeneration of the city’s quality. the recent recast energy performance regulation and the economic incentives it can provide to the owners if used for the design and implementation of interventions at the urban block scale can provide the opportunity for a holistic regeneration of the greek cities. methods 2.1. description of the analysed cases as mentioned above, two models of typical urban blocks are analysed in order to implement several renovation strategies and to compare their efficiency according to form and geometry factors. the first urban block is of discontinuous form, meaning that buildings are detached, while the second urban block is of continuous form, with buildings attached to the neighboring buildings in both their sides. the plans and 3d drawings of the two examined urban bocks are presented in fig. 1 and fig. 2, while parameters of geometry and size are presented in table 1. fig. 1. 3d representation drawing and plan of urban block typology 1 fig. 2. 3d representation drawing and plan of urban block typology 2 table 1. description of geometry parameters of the two examined urban blocks fig. 1 3d representation drawing and plan of urban block typology 1 fig. 2 3d representation drawing and plan of urban block typology 2 several assumptions about the orientation, road width and climatic conditions have been made in order to eliminate these parameters from the results, making conclusions about form and geometry clearer. both urban blocks are considered to have the same orientation (00) meaning that the north axis is parallel to the narrow side of the urban block plan. the road width for all the streets surrounding the urban block is 10 m, while the two urban blocks are situated in greek climatic zone c. greece is divided in four climatic zones (a, b c and d) according to the national energy performance of buildings regulation, with zone a representing the warmest climatic zone while zone d the coldest (greek regulation for the energy performance of buildings, fek 2367 2017). in detail, the investigation is carried out for the climatic conditions of the city of thessaloniki, which corresponds to a mediterranean climate with hot and quite dry summers and relatively dry winters. monthly average temperatures and monthly solar radiation values for the city of thessaloniki are presented in fig.3 (a and b). journal of sustainable architecture and civil engineering 2021/2/29 68 ub plot surface (m2) exposed shell (m2) volume (m3) road width (m) height (m) n. of floors coverage ratio floor area ratio surface to volume (s/v) 1 d 3608 8965 17271 10 13 4 0.4 1.4 0.5 2 c 6864 33835 102391 10 22 7 0.7 4.7 0.3 several assumptions about the orientation, road width and climatic conditions have been made in order to eliminate these parameters from the results, making conclusions about form and geometry clearer. both urban blocks are considered to have the same orientation (00) meaning that the north axis is parallel to the narrow side of the urban block plan. the road width for all the streets surrounding the urban block is 10 m, while the two urban blocks are situated in greek climatic zone c. greece is divided in four climatic zones (a, b c and d) according to the national energy performance of buildings regulation, with zone a representing the warmest climatic zone while zone d the coldest (greek regulation for the energy performance of buildings, fek 2367 2017). in detail, the investigation is carried out for the climatic conditions of the city of thessaloniki, which corresponds to a mediterranean climate with hot and quite dry summers and relatively dry winters. monthly average temperatures and monthly solar radiation values for the city of thessaloniki are presented in fig.3 (a and b). a b fig. 3. a. monthly average temperature and b. monthly solar radiation for the city of thessaloniki the research investigates the way the urban block form and geometry can affect the performance of energy upgrading strategies and installations. therefore, four different energy upgrading scenarios are analysed for each urban block according to energy efficiency criteria: 1. building shell thermal insulation. 2. green roof construction. 3. smart materials use (phase change materials). 4. passive solar systems (sunspaces). the four scenarios are also designed according to three main aesthetic criteria:  the vertical organization of all mechanical installations in specific positions of the building facades.  the pre-installation design of solar collectors and / or photovoltaic panels. ub plot surface (m2) exposed shell (m2) volume (m3) road width (m) height (m) n. of floors coverage ratio floor area ratio surface to volume (s/v) 1 d 3608 8965 17271 10 13 4 0.4 1.4 0.5 2 c 6864 33835 102391 10 22 7 0.7 4.7 0.3 several assumptions about the orientation, road width and climatic conditions have been made in order to eliminate these parameters from the results, making conclusions about form and geometry clearer. both urban blocks are considered to have the same orientation (00) meaning that the north axis is parallel to the narrow side of the urban block plan. the road width for all the streets surrounding the urban block is 10 m, while the two urban blocks are situated in greek climatic zone c. greece is divided in four climatic zones (a, b c and d) according to the national energy performance of buildings regulation, with zone a representing the warmest climatic zone while zone d the coldest (greek regulation for the energy performance of buildings, fek 2367 2017). in detail, the investigation is carried out for the climatic conditions of the city of thessaloniki, which corresponds to a mediterranean climate with hot and quite dry summers and relatively dry winters. monthly average temperatures and monthly solar radiation values for the city of thessaloniki are presented in fig.3 (a and b). a b fig. 3. a. monthly average temperature and b. monthly solar radiation for the city of thessaloniki the research investigates the way the urban block form and geometry can affect the performance of energy upgrading strategies and installations. therefore, four different energy upgrading scenarios are analysed for each urban block according to energy efficiency criteria: 1. building shell thermal insulation. 2. green roof construction. 3. smart materials use (phase change materials). 4. passive solar systems (sunspaces). the four scenarios are also designed according to three main aesthetic criteria:  the vertical organization of all mechanical installations in specific positions of the building facades.  the pre-installation design of solar collectors and / or photovoltaic panels. the research investigates the way the urban block form and geometry can affect the performance of energy upgrading strategies and installations. therefore, four different energy upgrading scenarios are analysed for each urban block according to energy efficiency criteria: 1. building shell thermal insulation. 2. green roof construction. 3. smart materials use (phase change materials). 4. passive solar systems (sunspaces). the four scenarios are also designed according to three main aesthetic criteria: _ the vertical organization of all mechanical installations in specific positions of the building facades. _ the pre-installation design of solar collectors and / or photovoltaic panels. _ the unified constructional and architectural form for sun spaces and shading devices. in the first axis of the research, all the above-mentioned interventions are designed and simulated in order to calculate heating and cooling demand. the research intends to assess each one of the four interventions in order to define the degree that it can contribute in the reduction of energy demand for heating and cooling. the energyplus 9.2.0 software, which is one of the most commonly used programs for modeling the energy performance in buildings, has been used for the energy simulations. all the simulations have been run for one year, using the standard iwec weather files of thessaloniki city. with regard to the heat balance algorithm, the conduction transfer function is employed for all the investigated scenarios except for the pcm because of its nonlinear behavior. thus, in case of the pcm, the conduction finite difference algorithm (confd), that provides the opportunity to simulate materials with variable properties such as pcm, was used. within this respect, the confd method is coupled with an enthalpy-temperature function to simulate phasechange processes. furthermore, the default confd model with 20 time steps per hour is used to assess the annual energy demand for all the examined cases, as recommended by (tabares-velasco, christensen, and bianchi 2012). in the second axis of the research, an aesthetic approach of the interventions in an overall urban block architectural design is proposed for each urban block. the design intends, on the one hand to prove that similar energy upgrading interventions can be applied at the urban block scale (as opposed to individual buildings) without compromising the aesthetic quality of the city and on the other hand it intends to give directions on how to develop guidance for developing policies and strategies in order to promote the energy upgrading interventions according to the urban block form and geometry. a b fig. 3 a. monthly average temperature and b. monthly solar radiation for the city of thessaloniki 69 journal of sustainable architecture and civil engineering 2021/2/29 buildings’ construction and operation conditions several assumptions have also been made for the buildings’ construction and operation parameters. it has been assumed that all buildings have residential use on all typical floors and a retail use on the ground floor, meaning they have a similar operation and occupation schedule, respectively. according to the greek building legislation framework, residence and retail are occupied 18h and 9h per day, respectively. in addition, both residence and retail zones are temperature – controlled using the ideal load hvac system, which removes the heat at 100% efficiency in order to supply conditioned air to the zones, meeting the load demands. therefore, hvac system schedules were matched to the occupancy schedules and a dual setpoint thermostat was selected to control the indoor temperature. the thermostat setpoint was set to 20 °c for heating and 26 °c for cooling, as recommended by the greek regulation for the energy performance of buildings (greek regulation for the energy performance of buildings, fek 2367 2017) for residential and retail building uses. as far as ventilation is concerned, a constant rate of 1.25 ach and 1.75 ach is considered for hygienic purposes during the occupied hours in terms of residence and retail, respectively, while an additional night ventilation is introduced between 22:30 and 07:00. in addition, all buildings also have the same constructional system of concrete load bearing elements and brick masonry walls (which is the most typical construction system used in the greek apartment buildings). description of the energy upgrading intervention scenarios first, a base case scenario has been considered in order to be compared with all the intervention scenarios. for the base case scenario all building elements (walls, roofs, beams and columns) have been assumed to be non – insulated, having poor airtightness, with an infiltration rate equal to 2 ach during the whole day. a. thermal insulation scenario the first scenario includes the conventional thermal insulation of the building shell, according to the minimum permitted values of the national energy performance of buildings regulation (kenak) for refurbished buildings, as well as the buildings’ airtightness improvement, as the infiltration rate is considered equal to 1 ach. additional interventions are considered in the other three scenarios. the u-values of all building elements for the base case scenario and for the four upgrading scenarios, where thermal insulation is added on the building shell, are presented in table 2. building element description base case scenario thermal insulation scenarios u-value (w / m2k) u-value (w / m2k) walls exterior reinforced concrete elements 3.25 0.45 exterior brick masonry 1.72 0.45 slabs interior r.c. slabs 2.74 2.74 flat roof 2.11 0.40 reinforced concrete slab on ground 2.65 0.75 openings windows 5.81 2.80 doors 5.81 2.80 table 2 material’s thermal properties description for the base case scenario and for the thermal insulation scenarios journal of sustainable architecture and civil engineering 2021/2/29 70 b. green roof scenario as the existing buildings’ structural system has not been designed to carry the loads of a green roof, for the second scenario an extensive green roof type has been considered for all the flat roof surfaces of the urban block. extensive green roof types are thin lightweight roof systems that typically have a planting media measuring 6 to 20 cm. for the simulations, a 9 cm soil has been considered, corresponding to a u-value of 0.3 w / m2. k. c. phase change materials scenario for scenario 3 the phase change materials (pcm) taken into account are embedded in a 3 cm smart board in all the exterior walls and all walls facing a non-heated space, in order to both reduce the energy demands and to improve the indoor thermal comfort. for the continuous form urban block pcm board have also been placed in the adjacent walls between buildings in both sides. regarding the pcm thermophysical properties, a smart board with a phase change temperature of 25 °c, a phase change enthalpy equal to 110 kj / kg and a thermal conductivity λ = 0.23 w / m . k has been considered. d. passive solar and shading scenario the fourth scenario concerns the installation of passive solar and shading systems. sunspaces are proposed for balconies, and the buildings’ last floor recession and the design of shading as well. they are closed volumes, constituted by transparent surfaces, adjacent to the buildings which reduce heating load through solar gains. the glass material is assumed to be the same as the glass material of the transparent elements of the buildings in scenarios 1-4, with a u-value equal to 2.8 w / m2 . k, as specified in table 2, and a solar heat gain coefficient equal to 0.45. furthermore, in order to avoid summer overheating, sunspaces are modelled to be opened between the middle of may and the end of september as well as to be equipped with shading devices. in detail, for an efficient use of solar heat gains, sunspaces transparent surfaces are provided with an external movable shading device. from october to the middle of may, these devices are pulled back in order to maximize solar gains. on the contrary, from the middle of may to october, the shading devices are lowered with slats set to 90 degrees to minimize solar heat gains. design of the interventions for the improvement of building aesthetics four main criteria were applied: first, the arrangement of mechanical installations on building facades and the design of vertical cladding elements behind which all installations (air conditioning units / natural gas units etc.). the appropriate ventilation is provided by using perforated cladding or horizontal blinds on steel structure. second, passive solar systems in the form of sun spaces are used in order not only to improve energy performance, but also in order to provide a common structure for shading elements which are intended to replace the existing awnings. shadings systems in balconies are also used often not only for shading needs, but also in order to protect from the wind, rain, dust or even for providing a more private space protected from the sight of neighbors. third, solar collectors for hot water and photovoltaics are also considered in terms of a pre-installation design in roof tops. this strategy intends to prevent future random positioning of such installations and to create a ready to use substructure which will be integrated in the urban block form. fourth, green roofs have also been designed on rooftops in order to take into account the previously mentioned installation of solar systems on the rooftops and to produce a unified aesthetic quality on the urban blocks skyline. 71 journal of sustainable architecture and civil engineering 2021/2/29 all the above-mentioned aesthetic interventions were adjusted in the form and geometry of each of the two examined urban blocks and are presented in detail in the following sections. a. urban block 1 the discontinuous typology examined is characterized by the fact that the front and rear façade have openings and balconies while the side facades have a larger opaque surface as they have very few small openings or no openings at all, depending on the position of the staircase. this is the reason why these side walls have been chosen as more appropriate for placing all the necessary mechanical equipment. a large surface of the façade remains opaque and is considered suitable for placing a second skin, which is designed in an appropriate distance from the existing wall, in order to have enough space for the mechanical equipment that is intended to cover. for the sunspaces positioning, a sun study has been performed in order to define the most effective way to design these spaces. as sun spaces are supposed to be deactivated during the summer months, by opening all their façade transparent leaves, the sun study was performed for the heating period. the direct solar availability for the 21st of december has been considered (fig. 4) and as it is obvious, only the south oriented last floor balconies of the buildings have direct sunlight during december. therefore, the sunspaces have been designed only in these balconies (fig. 5). however, in the corners of the urban blocks, due to the geometry of the crossing streets sunspaces have been proposed for the south-east and south-west balconies in all floors. these sunspaces might not be as effective in terms of solar gains, but they can still contribute, and they can also function as a restraint zone for heat loss. fig. 4 sun study showing the sun position the 21st of december at noon achieve maximum efficiency) and they are installed in random positions resulting not only on the bad aesthetics of the fifth façade of the building (e.g. the flat roof), but also on the inefficient utilization of the surface of the roof. the situation is similar with the residential photovoltaics which cover the rooftops of buildings altering the aesthetic of the city to the worse. solar collectors or photovoltaic panels pre-installation surfaces have been designed on the rooftops of the buildings. the surfaces are inclined according to the need for maximum direct solar radiation (30o) and they are positioned in the perimeter of the rooftops to leave the space unified for other uses (including green roof installation). fig. 4. sun study showing the sun position the 21st of december at noon fig. 5. perspective view showing interventions in the urban block typology 1 for corner and middle positioned buildings b. urban block 2 in the continuous typology of urban block 2 which is examined, in contrast to the discontinuous form (urban block 1), the buildings are attached to each other forming a unified façade which has openings and balconies both towards the street and towards the uncovered space at the center of the urban block (inner court). however, the façade elements are interrupted by a regulatory limitation which imposes the distance of balconies from the plots side boundary. according to this restriction the urban block façade has vertical opaque surfaces between the buildings extended in all floors and having a 2 m width. this space could be appropriate for installing all mechanical equipment which can be hidden behind the construction of a second skin extending in all floors between the buildings’ balconies. for the sunspaces positioning, a sun study has been performed for this typology as well in order to define the most effective way to design these spaces. the direct solar availability for the 21st of december has been calculated as presented in fig. 6 and, as it is obvious, only the last two floors of the achieve maximum efficiency) and they are installed in random positions resulting not only on the bad aesthetics of the fifth façade of the building (e.g. the flat roof), but also on the inefficient utilization of the surface of the roof. the situation is similar with the residential photovoltaics which cover the rooftops of buildings altering the aesthetic of the city to the worse. solar collectors or photovoltaic panels pre-installation surfaces have been designed on the rooftops of the buildings. the surfaces are inclined according to the need for maximum direct solar radiation (30o) and they are positioned in the perimeter of the rooftops to leave the space unified for other uses (including green roof installation). fig. 4. sun study showing the sun position the 21st of december at noon fig. 5. perspective view showing interventions in the urban block typology 1 for corner and middle positioned buildings b. urban block 2 in the continuous typology of urban block 2 which is examined, in contrast to the discontinuous form (urban block 1), the buildings are attached to each other forming a unified façade which has openings and balconies both towards the street and towards the uncovered space at the center of the urban block (inner court). however, the façade elements are interrupted by a regulatory limitation which imposes the distance of balconies from the plots side boundary. according to this restriction the urban block façade has vertical opaque surfaces between the buildings extended in all floors and having a 2 m width. this space could be appropriate for installing all mechanical equipment which can be hidden behind the construction of a second skin extending in all floors between the buildings’ balconies. for the sunspaces positioning, a sun study has been performed for this typology as well in order to define the most effective way to design these spaces. the direct solar availability for the 21st of december has been calculated as presented in fig. 6 and, as it is obvious, only the last two floors of the fig. 5 perspective view showing interventions in the urban block typology 1 for corner and middle positioned buildings journal of sustainable architecture and civil engineering 2021/2/29 72 green roofs are designed on the rooftop surface of each building and some pergolas for climbing plants are also added in order to provide shading. solar collectors and photovoltaic panels, as already mentioned before, are not included in this study in terms of energy efficiency as they are not a part of the building shell, however they are considered as a possible future installation on the rooftops which might influence the aesthetic appearance of the city. in most cases there are no rules for their installation (except from the need to be inclined in order to achieve maximum efficiency) and they are installed in random positions resulting not only on the bad aesthetics of the fifth façade of the building (e.g. the flat roof), but also on the inefficient utilization of the surface of the roof. the situation is similar with the residential photovoltaics which cover the rooftops of buildings altering the aesthetic of the city to the worse. solar collectors or photovoltaic panels pre-installation surfaces have been designed on the rooftops of the buildings. the surfaces are inclined according to the need for maximum direct solar radiation (30o) and they are positioned in the perimeter of the rooftops to leave the space unified for other uses (including green roof installation). b. urban block 2 in the continuous typology of urban block 2 which is examined, in contrast to the discontinuous form (urban block 1), the buildings are attached to each other forming a unified façade which has openings and balconies both towards the street and towards the uncovered space at the center of the urban block (inner court). however, the façade elements are interrupted by a regulatory limitation which imposes the distance of balconies from the plots side boundary. according to this restriction the urban block façade has vertical opaque surfaces between the buildings extended in all floors and having a 2 m width. this space could be appropriate for installing all mechanical equipment which can be hidden behind the construction of a second skin extending in all floors between the buildings’ balconies. for the sunspaces positioning, a sun study has been performed for this typology as well in order to define the most effective way to design these spaces. the direct solar availability for the 21st of december has been calculated as presented in fig. 6 and, as it is obvious, only the last two floors of the buildings have direct sunlight during december. therefore, the sunspaces for the reduction of heating loads have been designed only in these floors. fig. 6 sun study showing the sun position the 21st of december at noon buildings have direct sunlight during december. therefore, the sunspaces for the reduction of heating loads have been designed only in these floors. it should be noted that in this typology the last floor is recessed from the subjective floor and the geometry of the sunspace follows the geometry of the recession in order to comply with the regulatory restriction which imposed the recession of the last floor in the first place. for this reason, the sunspace is designed with inclined roof surfaces which besides the morphological reasons should also contribute on the efficiency of the sunspaces, as the sun rays hit the inclined glass more vertically (fig. 7). fig. 6. sun study showing the sun position the 21st of december at noon the design of the sunspaces in the last floor of this typology includes sunspaces in all orientations as these floors have increased heat losses. the last floor has always larger heat losses from the building shell compared to inferior floors due to the upper slab facing the interior. in this case the last floor has a recession which increases the surface of the exposed shell even more due to the geometry of the recession. the north facing buildings of the urban block are in an even more disadvantaged situation as solar availability is low due to orientation. therefore, the sunspaces are designed mainly as heat restraint zones as in the case the orientation (north oriented facades) of the building does not favor passive solar gains. this choice has also architectural advantages as owners of these last recessed floors often construct illegal shading overhangs, awnings or even pergolas as these verandas suffer from the exterior climatic conditions (wind, rain, sun) in which they are exposed due to the fact that they are in a height where normally wind speed and sun radiation is higher and rainfall is harder as there are no obstructions from the neighboring buildings at this level. in the subjective floor the sunspaces’ design follows the same geometry as in typology 1 including sunspaces in all balconies for the fifth floor and in the corners of the urban block as well. solar collectors or photovoltaic panels’ pre-installation surfaces have been designed inclined according to the need for maximum direct solar radiation on the rooftop’s south perimeter in an analogous way as in urban block typology 1. these surfaces are also a safety boundary towards the rooftops edge (replacing existing railings). green roofs are designed, on the rooftops surface of each building in the remaining free space. fig. 7. perspective view showing interventions in the urban block typology 2 it should be noted that in this typology the last floor is recessed from the subjective floor and the geometry of the sunspace follows the geometry of the recession in order to comply with the regulatory restriction which imposed the recession of the last floor in the first place. for this reason, the sunspace is designed with inclined roof surfaces which besides the morphological reasons should also contribute on the efficiency of the sunspaces, as the sun rays hit the inclined glass more vertically (fig. 7). 73 journal of sustainable architecture and civil engineering 2021/2/29 buildings have direct sunlight during december. therefore, the sunspaces for the reduction of heating loads have been designed only in these floors. it should be noted that in this typology the last floor is recessed from the subjective floor and the geometry of the sunspace follows the geometry of the recession in order to comply with the regulatory restriction which imposed the recession of the last floor in the first place. for this reason, the sunspace is designed with inclined roof surfaces which besides the morphological reasons should also contribute on the efficiency of the sunspaces, as the sun rays hit the inclined glass more vertically (fig. 7). fig. 6. sun study showing the sun position the 21st of december at noon the design of the sunspaces in the last floor of this typology includes sunspaces in all orientations as these floors have increased heat losses. the last floor has always larger heat losses from the building shell compared to inferior floors due to the upper slab facing the interior. in this case the last floor has a recession which increases the surface of the exposed shell even more due to the geometry of the recession. the north facing buildings of the urban block are in an even more disadvantaged situation as solar availability is low due to orientation. therefore, the sunspaces are designed mainly as heat restraint zones as in the case the orientation (north oriented facades) of the building does not favor passive solar gains. this choice has also architectural advantages as owners of these last recessed floors often construct illegal shading overhangs, awnings or even pergolas as these verandas suffer from the exterior climatic conditions (wind, rain, sun) in which they are exposed due to the fact that they are in a height where normally wind speed and sun radiation is higher and rainfall is harder as there are no obstructions from the neighboring buildings at this level. in the subjective floor the sunspaces’ design follows the same geometry as in typology 1 including sunspaces in all balconies for the fifth floor and in the corners of the urban block as well. solar collectors or photovoltaic panels’ pre-installation surfaces have been designed inclined according to the need for maximum direct solar radiation on the rooftop’s south perimeter in an analogous way as in urban block typology 1. these surfaces are also a safety boundary towards the rooftops edge (replacing existing railings). green roofs are designed, on the rooftops surface of each building in the remaining free space. fig. 7. perspective view showing interventions in the urban block typology 2 the design of the sunspaces in the last floor of this typology includes sunspaces in all orientations as these floors have increased heat losses. the last floor has always larger heat losses from the building shell compared to inferior floors due to the upper slab facing the interior. in this case the last floor has a recession which increases the surface of the exposed shell even more due to the geometry of the recession. the north facing buildings of the urban block are in an even more disadvantaged situation as solar availability is low due to orientation. therefore, the sunspaces are designed mainly as heat restraint zones as in the case the orientation (north oriented facades) of the building does not favor passive solar gains. this choice has also architectural advantages as owners of these last recessed floors often construct illegal shading overhangs, awnings or even pergolas as these verandas suffer from the exterior climatic conditions (wind, rain, sun) in which they are exposed due to the fact that they are in a height where normally wind speed and sun radiation is higher and rainfall is harder as there are no obstructions from the neighboring buildings at this level. in the subjective floor the sunspaces’ design follows the same geometry as in typology 1 including sunspaces in all balconies for the fifth floor and in the corners of the urban block as well. solar collectors or photovoltaic panels’ pre-installation surfaces have been designed inclined according to the need for maximum direct solar radiation on the rooftop’s south perimeter in an analogous way as in urban block typology 1. these surfaces are also a safety boundary towards the rooftops edge (replacing existing railings). green roofs are designed, on the rooftops surface of each building in the remaining free space. fig. 7 perspective view showing interventions in the urban block typology 2 methods energy efficiency assessment of the interventions first the heating and cooling load demand has been calculated for the base case scenario of each one of the two urban block typologies. then, the heating and cooling load demand has been calculated for each one of the four scenarios of the two examined typologies. the results of the heating and of the cooling demand of the base case, compared to the four scenarios for the two urban blocks, are presented in fig. 8 and fig. 9. fig. 8 comparison of the heating demand between the continuous and the discontinuous urban block form for all the examined scenarios results 3.1. energy efficiency assessment of the interventions first the heating and cooling load demand has been calculated for the base case scenario of each one of the two urban block typologies. then, the heating and cooling load demand has been calculated for each one of the four scenarios of the two examined typologies. the results of the heating and of the cooling demand of the base case, compared to the four scenarios for the two urban blocks, are presented in fig. 8 and fig. 9. for ub1 heating demand is calculated to be 187.4 kwh/m2 for the base case scenario and it is reduced to 81 kwh/m2, 79.0 kwh/m2 80.2 kwh/m2and 79.3 kwh/m2 for scenario 1, 2, 3, and 4 respectively. cooling demand is calculated to be 27.1 kwh/m2 for the base case scenario and it is reduced to 14.0 kwh/m2, 12.2 kwh/m2, 13.2 kwh/m2 and 13.3 kwh/m2 for scenario 1, 2, 3, and 4 respectively. for ub2 heating demand is calculated to be 164.0 kwh/m2 for the base case scenario and it is reduced to 68.5 kwh/m2, 67.2 kwh/m2 68.4 kwh/m2and 66.4 kwh/m2 for scenario 1, 2, 3, and 4 respectively. cooling demand is calculated to be 21.4 kwh/m2 for the base case scenario and it is reduced to 10.8 kwh/m2, 9.3 kwh/m2, 10.4 kwh/m2 and 10.1 kwh/m2 for scenario 1, 2, 3, and 4 respectively. as it can be remarked, both heating and cooling demand are significantly reduced in all scenarios when compared to the base case scenario. the energy demand for heating and cooling is more than halved. the effect of all interventions on the reduction of the heating demand is more intense than the reduction for the cooling demand. it is also important to note that for the base case and all interventions scenarios urban block 1 presents higher values for both heating and cooling load demand than urban block 2, which means that the more compact urban block form appears to have a better energy performance in all cases. however, it is important to examine the effect of each one of these interventions on the energy demand of each urban block to assess their efficiency and to compare the scenarios. fig. 8. comparison of the heating demand between the continuous and the discontinuous fig. 9. comparison of the cooling demand between the continuous and the discontinuous journal of sustainable architecture and civil engineering 2021/2/29 74 for ub1 heating demand is calculated to be 187.4 kwh/m2 for the base case scenario and it is reduced to 81 kwh/m2, 79.0 kwh/m2 80.2 kwh/m2and 79.3 kwh/m2 for scenario 1, 2, 3, and 4 respectively. cooling demand is calculated to be 27.1 kwh/m2 for the base case scenario and it is reduced to 14.0 kwh/m2, 12.2 kwh/m2, 13.2 kwh/m2 and 13.3 kwh/m2 for scenario 1, 2, 3, and 4 respectively. for ub2 heating demand is calculated to be 164.0 kwh/m2 for the base case scenario and it is reduced to 68.5 kwh/m2, 67.2 kwh/m2 68.4 kwh/m2and 66.4 kwh/m2 for scenario 1, 2, 3, and 4 respectively. cooling demand is calculated to be 21.4 kwh/m2 for the base case scenario and it is reduced to 10.8 kwh/m2, 9.3 kwh/m2, 10.4 kwh/m2 and 10.1 kwh/m2 for scenario 1, 2, 3, and 4 respectively. as it can be remarked, both heating and cooling demand are significantly reduced in all scenarios when compared to the base case scenario. the energy demand for heating and cooling is more than halved. the effect of all interventions on the reduction of the heating demand is more intense than the reduction for the cooling demand. it is also important to note that for the base case and all interventions scenarios urban block 1 fig. 9 comparison of the cooling demand between the continuous and the discontinuous urban block form for all the examined scenarios table 3 improvement for the heating and the cooling demand (percentage of reduction) for the discontinuous and the continuous urban block form through the thermal insulation scenario (1). comparison to the base case (all floors) urban block form heating demand cooling demand total demand discontinuous 56.8 % 48.3 % 55.7 % continuous 58.2 % 49.5 % 57.2 % results 3.1. energy efficiency assessment of the interventions first the heating and cooling load demand has been calculated for the base case scenario of each one of the two urban block typologies. then, the heating and cooling load demand has been calculated for each one of the four scenarios of the two examined typologies. the results of the heating and of the cooling demand of the base case, compared to the four scenarios for the two urban blocks, are presented in fig. 8 and fig. 9. for ub1 heating demand is calculated to be 187.4 kwh/m2 for the base case scenario and it is reduced to 81 kwh/m2, 79.0 kwh/m2 80.2 kwh/m2and 79.3 kwh/m2 for scenario 1, 2, 3, and 4 respectively. cooling demand is calculated to be 27.1 kwh/m2 for the base case scenario and it is reduced to 14.0 kwh/m2, 12.2 kwh/m2, 13.2 kwh/m2 and 13.3 kwh/m2 for scenario 1, 2, 3, and 4 respectively. for ub2 heating demand is calculated to be 164.0 kwh/m2 for the base case scenario and it is reduced to 68.5 kwh/m2, 67.2 kwh/m2 68.4 kwh/m2and 66.4 kwh/m2 for scenario 1, 2, 3, and 4 respectively. cooling demand is calculated to be 21.4 kwh/m2 for the base case scenario and it is reduced to 10.8 kwh/m2, 9.3 kwh/m2, 10.4 kwh/m2 and 10.1 kwh/m2 for scenario 1, 2, 3, and 4 respectively. as it can be remarked, both heating and cooling demand are significantly reduced in all scenarios when compared to the base case scenario. the energy demand for heating and cooling is more than halved. the effect of all interventions on the reduction of the heating demand is more intense than the reduction for the cooling demand. it is also important to note that for the base case and all interventions scenarios urban block 1 presents higher values for both heating and cooling load demand than urban block 2, which means that the more compact urban block form appears to have a better energy performance in all cases. however, it is important to examine the effect of each one of these interventions on the energy demand of each urban block to assess their efficiency and to compare the scenarios. fig. 8. comparison of the heating demand between the continuous and the discontinuous fig. 9. comparison of the cooling demand between the continuous and the discontinuous presents higher values for both heating and cooling load demand than urban block 2, which means that the more compact urban block form appears to have a better energy performance in all cases. however, it is important to examine the effect of each one of these interventions on the energy demand of each urban block to assess their efficiency and to compare the scenarios. a. thermal insulation scenario the comparison between the base case scenario and scenario 1 (thermal insulation scenario) is presented in table 3. as it is observed for the discontinuous urban block form, the total energy demand is reduced by 55.7 % while, for the continuous urban block form, it is reduced by 57.2 %. this urban block form for all the examined scenarios urban block form for all the examined scenarios fig. 10. comparison of the total demand between the continuous and the discontinuous urban block form for all the examined scenarios a. thermal insulation scenario the comparison between the base case scenario and scenario 1 (thermal insulation scenario) is presented in table 3. as it is observed for the discontinuous urban block form, the total energy demand is reduced by 55.7 % while, for the continuous urban block form, it is reduced by 57.2 %. this means that the thermal insulation of the building shell can have a stronger effect on the energy efficiency of continuous urban forms. for urban block 2, both the heating and the cooling demand present a larger percentage of reduction in this upgrading intervention scenario. the difference in the percentage reduction of the total energy demand between the discontinuous and the continuous form indicates that the building shells’ thermal insulation renovation scenario can, by 1.5 %, be more efficient according to the urban blocks form and geometry. table 3. improvement for the heating and the cooling demand (percentage of reduction) for the discontinuous and the continuous urban block form through the thermal insulation scenario (1). comparison to the base case (all floors) urban block form heating demand cooling demand total demand discontinuous 56.8 % 48.3 % 55.7 % continuous 58.2 % 49.5 % 57.2 % b. pcm scenario the comparison between the base case scenario and scenario 2 (pcm scenario) is presented in table 4. as it is observed for the discontinuous urban block form, the total energy demand is reduced by 57.5 % while, for the continuous urban block form, it is reduced by 58.7 %. this means that the increase in the fig. 10 comparison of the total demand between the continuous and the discontinuous urban block form for all the examined scenarios means that the thermal insulation of the building shell can have a stronger effect on the energy efficiency of continuous urban forms. for urban block 2, both the heating and the cooling demand present a larger percentage of reduction in this upgrading intervention scenario. the difference in the percentage reduction of the total energy demand between the discontinuous and the continuous form indicates that the building shells’ thermal insulation renovation scenario can, by 1.5 %, be more efficient according to the urban blocks form and geometry. 75 journal of sustainable architecture and civil engineering 2021/2/29 b. pcm scenario the comparison between the base case scenario and scenario 2 (pcm scenario) is presented in table 4. as it is observed for the discontinuous urban block form, the total energy demand is reduced by 57.5 % while, for the continuous urban block form, it is reduced by 58.7 %. this means that the increase in the effect of the thermal mass of the building does not alter the fact that the continuous form presents a higher percentage improvement in comparison to the base case. both the heating and the cooling demand present a larger percentage of reduction for this upgrading intervention scenario. it is also interesting to note that the pcm can improve the energy performance of thermally insulated urban blocks of discontinuous form by 4.0 % and of continuous urban blocks by 3.5 %. this means that increasing thermal mass could be a more effective intervention on insulated discontinuous buildings than on insulated continuous urban blocks. urban block form heating demand cooling demand total demand discontinuous 57.8 % 55.1 % 57.5 % continuous 59.0 % 56.4 % 58.7 % c. green roof scenario the third upgrading scenario consists of the construction of a green roof on the rooftop of all buildings of each examined urban block. as it has been mentioned the u-value of the roof is reduced by 0.1, but the green roof also contributes on the increase of thermal mass of the roof and of the reduction of incident solar radiation. this means that it is expected to reduce further the heating and cooling load demand of the urban block compared to scenario 1. it can be remarked by the percentages presented in table 5 that the green roof can reduce the heating load demand table 4 improvement for the heating and the cooling demand (percentage of reduction) for the discontinuous and the continuous urban block form through the pcm scenario (2). comparison to the base case (all floors) table 5 improvement for the heating and cooling demand (percentage of reduction) for the discontinuous and the continuous urban block form through the green roof scenario (3). comparison to the base case (all floors) urban block form heating demand cooling demand total demand discontinuous 57.2 % 51.2 % 56.5 % continuous 58.3 % 51.5 % 57.5 % of urban block (ub) 1 (discontinuous) by 57.2 % and of urban block 2 (continuous) by 58.3 % as far as it concerns cooling load demand it is remarked that it is reduced by 51.2 % for ub 1 and by 51.5 % for ub 2. finally, the total energy demand is reduced by 56.5 % and by 57.5 % for urban block 1 and 2 respectively. the comparison of the intervention to the base case scenario shows that this intervention scenario (green roof) can be more effective in the continuous urban block form, but this conclusion is rather forced by the very high effect of the thermal insulation on the reduction of the total energy demand of the urban blocks. the comparison of scenario 1 (thermal insulation) and scenario 3 (green roof) urban block form heating demand cooling demand total demand discontinuous 1.0 % 5.6 % 1.7 % continuous 0.2 % 4.0 % 0.7 % table 6 improvement for the heating and cooling demand (percentage of reduction) for the discontinuous and the continuous urban block form through the green roof scenario (3). comparison to scenario 1 (all floors) shows that the energy saving effect of the green roof is 1.7 % for the discontinuous form and 0.7 % for the continuous form, which means that the green roof is more effective on the insulated discontinuous form (table 6). in fact, this intervention could be considered to have a significant contribution mainly in the cooling load demand as the heating load demand improvement is very small in both cases. journal of sustainable architecture and civil engineering 2021/2/29 76 table 7 improvement for the heating and cooling demand (percentage of reduction) for the discontinuous and the continuous urban block form through the green roof scenario (3). comparison to scenario 1 (last floor) urban block form heating demand cooling demand total demand discontinuous 3.5 % 15.2 % 5.1 % continuous 3.5 % 15.5 % 5.0 % table 8 improvement for the heating and the cooling demand (percentage of reduction) for the discontinuous and the continuous urban block, through the passive solar and shading scenario (4). comparison to the base case (all floors) urban block form heating demand cooling demand total demand discontinuous 57.7 % 51.1 % 56.9 % continuous 59.5 % 53.1 % 58.8 % as the effect of the green roof is mostly limited to the last floors’ energy demand, it is also interesting to examine the change of the heating and the cooling load only in the last floor of each urban block. the comparison between the last floor of scenario 1 and scenario 3 is presented in table 7. the improvement in the heating energy demand is 3.5% for both urban blocks, while the cooling load demand is slightly higher in urban block 2 (15.5 % in contrast to 15.2 % of urban block 1). however, when the total energy demand is considered the green roof can provide almost equal improvement for both urban blocks as the difference is less than 0.1 %. table 9 improvement for the heating and the cooling demand (percentage of reduction) for the discontinuous and the continuous urban block, through the passive solar and shading scenario (4). comparison to scenario 1 (last floor) urban block form heating demand cooling demand total demand discontinuous 7.95 % 17.58 % 9.22 % continuous 10.14 % 32.24 % 13.03 % d. passive solar and shading scenario the effect of sunspaces and shading on the overall energy demand of the urban block is examined. as it is observed by the percentages of improvement of the heating and cooling load demand presented in table 8 the total load demand improvement of this intervention, compared to the base case scenario, is 56.9 % for the discontinuous urban block and 58.8 % for the continuous urban block. the contribution of the sunspaces on the last floor is obviously more important as in this floor, for both examined urban blocks, passive solar gains are significantly increased. the comparison of the last floor’s energy demand in the case of scenario 1 (thermal insulation) and scenario 4 (sunspaces) proves that the sunspaces’ intervention is far more effective in the continuous urban block form as the reduction of the total energy demand is 13.03% in comparison to 9.22% for the discontinuous form (table 9). it is also important to note that the effect of this intervention scenario in cooling load demand is very important, as it can contribute on the reduction of cooling load demand between 17.58 % and 32.24% for the discontinuous and the continuous form respectively. this reduction is due to shading design which obviously reduces significantly the direct solar radiation, especially in the continuous form (urban block 2) which due to the last floor’s recession is far more exposed to direct solar radiation than urban block 1. comparative assessment of the energy efficiency of the interventions in this section a comparative analysis of the above-mentioned interventions is described. first, the comparison among the three interventions to scenario 1 (thermal insulation) is presented in order to draw conclusions on the most energy efficient intervention for each period (heating and cooling) and for the whole year period as well. second, the comparison of the three interventions to scenario 1 is presented according to the urban block form to draw conclusions on the significance of form for the choice of the most efficient intervention. 77 journal of sustainable architecture and civil engineering 2021/2/29 the comparison of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) to scenario 1 (thermal insulation) (fig. 11) shows that for the heating load demand for ub1 the pcm intervention can provide the higher percentage of reduction. in this case, it is evident that the fact that the other two interventions cannot be installed in all floors is rather decisive. however, for ub2 the most efficient fig.11 heating demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig. 12 cooling demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig. 13 total demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig.11. heating demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig. 12. cooling demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig. 13. total demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) according to the above-mentioned comments, a renovation priority strategy should first target on discontinuous forms of urban blocks which demand more energy for heating and cooling. however, for already thermally insulated urban blocks, renovation including pcm, green roofs or sunspaces could improve more the efficiency of continuous forms and, among the examined scenarios, the renovation strategy which is more efficient in this case is the passive solar and shading scenario. fig.11. heating demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig. 12. cooling demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig. 13. total demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) according to the above-mentioned comments, a renovation priority strategy should first target on discontinuous forms of urban blocks which demand more energy for heating and cooling. however, for already thermally insulated urban blocks, renovation including pcm, green roofs or sunspaces could improve more the efficiency of continuous forms and, among the examined scenarios, the renovation strategy which is more efficient in this case is the passive solar and shading scenario. fig.11. heating demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig. 12. cooling demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) fig. 13. total demand improvement (percentage of reduction) of scenarios 2 (pcm), 3 (green roof) and 4 (passive solar) in comparison to scenario 1 (thermal insulation) according to the above-mentioned comments, a renovation priority strategy should first target on discontinuous forms of urban blocks which demand more energy for heating and cooling. however, for already thermally insulated urban blocks, renovation including pcm, green roofs or sunspaces could improve more the efficiency of continuous forms and, among the examined scenarios, the renovation strategy which is more efficient in this case is the passive solar and shading scenario. intervention is the construction of sunspaces and shading devices (scenario 4). for the cooling load demand, it is concluded that for both urban blocks the contribution of pcm is more significant than green roofs and passive solar and shading scenario (fig. 12), as it can provide a decrease between 13.3 % and 13.7 % depending on the form of the urban block. this however might have to do more with the fact that the melting point temperature chosen for the simulation of the pcm (25 oc) favors the phase change of the pcm during the cooling period. for the whole year period, it is concluded that the results are similar to those for the heating period (fig. 13), as in the greek climate heating degree days significantly exceed cooling degree days (tsikaloudaki, laskos, and bikas 2012). especially in the continuous urban block form, the sunspaces and shading are the most efficient scenario and considering that this intervention can only be installed in the last floor of urban block 1 it can also be considered as a very efficient one in terms of the energy improvement it can provide. the green roof scenario appears to be more efficient in the case of the discontinuous urban block and this intervention is mostly efficient during the cooling period as it has a very small contribution on the percentage of improvement during the heating period and especially for the continuous form (urban block 1) where the improvement is very small. it is also remarkable that all three interventions contribute more in the percentage reduction of the cooling load demand, which means that they are expected to be even more efficient in warmer climatic zones of greece (zone a and zone b). according to the above-mentioned comments, a renovation priority strategy should first target on discontinuous forms of urban journal of sustainable architecture and civil engineering 2021/2/29 78 blocks which demand more energy for heating and cooling. however, for already thermally insulated urban blocks, renovation including pcm, green roofs or sunspaces could improve more the efficiency of continuous forms and, among the examined scenarios, the renovation strategy which is more efficient in this case is the passive solar and shading scenario. in this research four intervention scenarios in two typical urban blocks have been examined, in order to compare renovation strategies in terms of the energy efficiency of the urban blocks and to propose a way to improve city aesthetics at the same time. the results of the research showed that among all the interventions, the most efficient one is the conventional thermal insulation of the building shell. urban block form and geometry can affect the energy efficiency of the thermal insulation renovation scenario by 1.5%, with the continuous form presenting higher efficiency. this percentage could be translated into thousands of kw/h saved, by considering only the difference in urban form. prioritization of renovation in areas with discontinuous urban block forms could be an effective strategy for the renovation of the existing building stock. however, it has already been proved by the current energy performance renovation practices that this intervention (e.g. thermal insulation) cannot significantly promote the aesthetic improvement of the greek city, except if additional measures are also considered for arranging mechanical installations and shading devices in an uniform way. on the other hand, in most existing buildings increasing the thickness of thermal insulation layer, beyond a certain point, is not feasible considering that there are several limitations of constructional, architectural, or functional nature. for example, increasing wall thickness beyond a certain point is not possible due to the building’s position near the plot boundaries. moreover, it can reduce daylighting access in the interior space or significantly reduce the width of balconies which can in some cases become too narrow to be functional. therefore, beyond the conventional scenario of thermal insulation, other strategies for improving further the energy performance of buildings should be considered. among the other three interventions examined, it is has been proved that the pcm intervention scenario and the passive solar and shading scenario could be the most efficient ones in terms of energy load demand reduction -depending on the form of the urban blockespecially for the cooling period where the load demand has been calculated to be significantly improved. the result of the research cannot be easily compared to existing research on renovation strategies, as in most cases the examination scale of the researches refers at the building scale. this research examined the results in a cumulative perspective assessing the whole energy demand at the urban block scale. the improvement of the passive solar intervention scenario resulted in a reduction of the heating load between 57.7 % and 59.5 %. similar research (assimakopoulos et al. 2020) for the city of athens resulted in a range of heating load demand reduction between 35 % and 60 % according to the examined floor. for the cooling load demand the current research resuted in a reduction between 51.1 % and 53.1 %. the research of asimakopoulos et al. concluded in a range of 32 % to 51 % according to the floor examined. considering the difference in scale and the difference in climate (athens belongs to climatic zone b), the results could be considered to be in accordance. it should be noted that the pcm scenario is, besides the thermal insulation scenario, the only one which can be implemented in all floors, as the passive solar and shading scenario can be implemented only in floors with unobstructed solar radiation while, the green roof can obviously be constructed on the roof of the last floor. pcm research on cooling energy saving is not easy to be compared to the current research results for several reasons. the main reasons are, the scale of the intervention, the building typology used for the simulations and the different melting point and thickness of the examined pcm material. a similar research at the building scale (two storey dediscussion 79 journal of sustainable architecture and civil engineering 2021/2/29 tached building) for athens concluded that the pcm can provide a cooling demand saving between 2.3 % and 3.5 % depending on the pcm melting point temperature (ascione et al. 2014). the current research concludes in a 13.3 % – 13.7 % improvement which is much higher improvement. this difference can be interpreted by the larger scale of the intervention which seems to optimize the use of pcm and the difference in climate between athens and thessaloniki. of course, further research is needed in order to define the most efficient strategy for the energy and aesthetic regeneration of the city. it is evident that the efficiency of each renovation strategy depends on several crucial factors which should be taken into account. the efficiency of each intervention scenario should be further examined according to the following factors which might differ significantly in the urban tissue or among different cities. first, the examination of different road width is essential in a further research as solar gains may vary significantly in case of wider streets. especially the passive solar and shading scenario which is largely affected by the solar access should be analysed in the case of different width of the streets. second, as the climatic conditions are a decisive factor when examining energy efficiency strategies, it is necessary to analyse the examined scenarios for all four climatic zones of greece. third, it should also be mentioned that this study is limited to the examination of one basic orientation for both urban blocks. results may vary in different orientations as solar access may change according to the street network and the geometry of the urban tissue. especially, the interventions of scenario 3 could have a significantly different contribution on the energy demand for heating and cooling. an overall strategy for the city regeneration should also take into account all possible orientations at the urban scale. fourth, this research examined two typologies of different form. more generalized results demand the further examination of urban typologies at the city scale. finally, as all interventions are dependent to the economic cost and the payback period of the initial investment it is also important to examine how these interventions are related to a cost benefit analysis. conclusion the way towards climate neutral cities and the target for nearly zero energy buildings, demand the improvement of the building stock in terms of energy efficiency. the conventional thermal insulation strategies that are mostly applied, despite the important contribution on decreasing heating and cooling energy load demand, should also be combined with other passive energy improvement strategies. these strategies can be a starting point for improving the aesthetic quality of the city. this research proposed an intervention strategy at the urban block scale in order to achieve both energy efficiency and improvement of the aesthetic quality of the city. total (heating and cooling) demand reduction has been proved that might be reduced between 55.7 % and 58.5 % according to the intervention scenario chosen. the maximum value corresponds to the passive solar and shading scenario. obviously, at the urban block scale it is necessary to consider urban form and urban geometry parameters in order to define the efficiency of the interventions. on the one hand, it has been proved that all interventions cannot be implemented at the same extend, as for example passive solar interventions depend on the solar access and green roofs depend on the available surface which relates to the urban block’s geometry. on the other hand, the extent to which each intervention can be implemented could be decisive for the energy performance improvement of the urban block, but in this case other parameters could also be important, as more extensive interventions imply higher investment cost. this research proved the importance of passive solar and shading strategies on both the improvement of energy efficiency and the city aesthetics. journal of sustainable architecture and civil engineering 2021/2/29 80 the pcm could provide a significant improvement in the energy efficiency ranging from 57.5 % to 58.7 % according to the urban block form, but as extensive construction works in the interior of buildings should be performed, their application should be carefully considered on a cost benefit analysis. green roofs can provide better results in cases where the decrease of cooling demand is a priority as it has been calculated that they can provide a reduction in cooling load demand ranging from 4 to 5.5 % compared to the thermal insulation scenario. however, green roofs can as well promote aesthetics, improve microclimate and citizen’s wellbeing, they are considered an important strategy for the quality of life in contemporary cities. finally, it has been proved that energy renovation strategies when implemented at the urban block scale (instead of fragmented individual buildings interventions) can contribute not only at the environmental improvement but also at the aesthetic regeneration of the city. references acknowledgment funding: this research is co-financed by greece and the european union (european social fund esf) through the operational programme «human resources development, education and lifelong learning 2014-2020» in the context of the project “sustainable interventions for the energy and aesthetic improvement of the city” (mis 5047805)”. van oorschot j. a. w. h., hofman e., halman j. i. m. upscaling large scale deep renovation in the dutch residential sector: a case study. in energy procedia; 2016. https://doi.org/10.1016/j.egypro.2016.09.165 european union. directive 2012/27/eu of the european parliament and of the council of 25 october 2012 on energy efficiency, amending directives 2009/125/ec and 2010/30/eu and repealing directives 2004/8/ec and 2006/32/ec. official journal of the european union 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org/10.1016/j.apenergy.2013.08.045 journal of sustainable architecture and civil engineering 2021/2/29 82 dimitra tsirigoti postdoc researcher aristotle university of thessaloniki, faculty of engineering, department of civil engineering main research area sustainable architecture, urban morphology, energy efficiency, energy renovation, building construction address university campus po box 429, 54124 thessaloniki, greece tel. 00306977666283 e-mail: dtsirigo@civil.auth.gr dimitrios zenginis phd candidate aristotle university of thessaloniki, faculty of engineering, department of civil engineering main research area energy efficiency, phase change materials (pcm), building construction address university campus po box 429, 54124 thessaloniki, greece tel. 00306977285829 e-mail: dzengini@civil.auth.gr about the authors dimitrios bikas professor emeritus aristotle university of thessaloniki, faculty of engineering, department of civil engineering main research area sustainable buildings, building construction, environmental design and assessment address university campus po box 429, 54124 thessaloniki, greece tel. 0030995763 e-mail: bikasd@civil.auth.gr this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 163 journal of sustainable architecture and civil engineering 2022/1/30 educational buildings should provide a secure, healthy, and comfortable indoor environment for students since they spend a noteworthy part of their time inside. the present study aims to identify and assess the key indicators related to the light and air quality of a campus classroom, which contributes to the health of students. the indicators are chosen from an existing green rating tool, the well building standard (wbs). the research methodology consists of three main phases; indicator selection, impact assessment, and validation process. the engagement of stakeholders was taken into the account in the entire research framework. the research findings showed that there is a considerable gap among the acceptable range of indoor air and the light quality of the classroom. this led to verifying various health issues among the students, including dryness and irritation of the skin and eyes, and consequently increased their dissatisfaction rate. the study provides some significant insights based on the obtained results, highlighting the importance of incorporating student health and wellness into educational building design and operations, including visual comfort and indoor air quality conditions, which are often worse than the stipulations in standards. keywords: educational buildings, indoor air and light quality, well building standard (wbs), health issues. indoor air and light quality assessment in a university campus classroom *corresponding author: farzaneh.aliakbari@polito.it indoor air and light quality assessment in a university campus classroom received 2021/12/13 accepted after revision 2022/03/21 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 163-182 doi 10.5755/j01.sace.30.1.30328 jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.30328 farzaneh aliakbari, sara torabi moghadam, and patrizia lombardi interuniversity department of regional and urban studies and planning, politecnico di torino, viale mattioli 39, turin 10125, italy abstract introduction studies on the health and wellness of occupants have received much attention in recent years among scholars. the health-centered approach regarding occupants is at the heart of two sustainable development goals (sdgs) of 3 “ensure healthy lives and promote well-being for all at all ages” and 4 “ensure inclusively and quality education for all and promote lifelong learning opportunities for all” (azizibabani & dehghani, 2017; bortolini & forcada, 2021; costanza et al., 2016; lynch, 2016). as stated by the national institute for occupational safety and health (niosh), indoor environmental quality (ieq) refers to the environmental quality of the buildings, in relation to the health and wellness of occupants (h. abdulaali et al., 2020; cdc indoor environmental quality niosh workplace safety and health topic, 2019; liang et al., 2014; torabi & mahdavinejad, 2021). the ieq is determined by a range of environmental factors, such as thermal comfort, lighting, acoustic quality, and indoor air quality (h. abdulaali et al., 2020; arif et al., 2016; liang et al., 2014; sarbu & sebarchievici, 2013). journal of sustainable architecture and civil engineering 2022/1/30 164 it is well accepted that indoor air and light quality issues have negative impacts on human health (lee & lee, 2019; marchetti et al., 2019; pacitto et al., 2020). particularly, students are considered more vulnerable to the poor ieq since they spend a noteworthy part of their time in the scholastic environment (arcega-cabrera et al., 2018; ferguson & solo-gabriele, 2016; iglesias-gonzález et al., 2020; ma et al., 2019; turunen et al., 2014). therefore, the educational buildings should provide a secure, healthy, and comfortable indoor environment for students (bortolini & forcada, 2021; zhu et al., 2021; zinzi et al., 2021). this study is motivated by the main concern of poor ieq in the campus buildings, which can lead to health issues, high virus transmission rates, and reductions in learning performance in the long term (annesi-maesano et al., 2013; daisey et al., 2003; turunen et al., 2014; veenhoven, 1989; zhu et al., 2021). to date, many studies have conducted research about the ieq influences on the health and wellness of students in educational buildings (badeche & bouchahm, 2021; jamaludin et al., 2016; tahsildoost & zomorodian, 2018). these studies have focused on the ieq assessment concept in campuses and its relationship with the satisfaction level of students, employing different quantitative and qualitative methodologies (e.g., measurements, surveys) (jamaludin et al., 2016; tahsildoost & zomorodian, 2018; turunen et al., n.d., 2014). a recent study has introduced a ‘green’ building as a building that reduces the negative impacts on the environment during its lifecycle. moreover, it focused on assessing green buildings through the environmental building rating systems (shamseldin, 2021). another study conducted a comprehensive literature review regarding the impact of ieq on the health and wellbeing of occupants (h. s. abdulaali et al., 2020). this study introduces malaysia’s green building index (gbi) and highlights the ieq as a fundamental criterion of the green building rating system to be considered while designing, constructing, and operating a building (either residential or non-residential) (h. s. abdulaali et al., 2020). moreover, the evaluation of ieq and student satisfaction levels regarding a campus building has been conducted by mohd amri sulaiman et al. (sulaiman et al., 2013), based on four main ieq parameters—thermal comfort, auroral comfort, indoor air quality, and lighting through on-site measurements and a questionnaire survey (sulaiman et al., 2013). similarly, another study has investigated the use of quantitative and qualitative methods (i.e., measurements of ieq parameters and post-occupancy evaluation) to explore the performance level of the building and user satisfaction, according to the gbi (khamidi et al., 2013). the above-mentioned studies have measured different ieq parameters, such as temperature, and humidity, for their specific case study in order to assess the sustainability level of the building. in addition, they analyzed the satisfaction level of users of the place by utilizing questionnaire surveys. however, none of the previous studies has selected key indicators relying on a green rating tool and measured the impact of ieq parameters in relation to the students’ health. in detail, they have not specifically focused on the measured-based process and have not compared their indicators assessment results with the targets of a rating system and standard. due to the complexity of this research field, this paper aims to identify and assess the key indicators related to the light and air quality of a campus classroom, which contributes to the health of students. it, therefore, addresses the following research questions: “what are the key indicators related to the light and air quality which contribute to the health of students? and how these indicators can be selected and assessed?”. this study selects a specific measure-based tool and its relative indicators to realistically measure the most important factors of ieq in the campus buildings influencing student health and wellness. at present, the green school concept is of great importance and efforts are being made to raise awareness of sustainable development (meiboudi et al., 2018; zhao et al., 2015). in 2018, a comprehensive review on six green school rating systems which have been distributed worldwide was conducted (meiboudi et al., 2018). these global rating systems were developed in various 165 journal of sustainable architecture and civil engineering 2022/1/30 countries, including the building research establishment environmental assessment method (breeam) in the united kingdom, leadership in energy and environmental design (leed) in the united states, foundation for environmental education (fee) for eco-schools in europe, green star education in australia, comprehensive assessment system for building environmental efficiency (casbee) in japan, and china society for urban studies (csus) in china (meiboudi et al., 2018). moreover, the university of indonesia (ui) green metric world university ranking has been introduced as an international rating system to assess the situation of green campuses (uwi, 2016). in 2016, the well building standard (wbs) for educational facilities in the united states was launched, to work beside leed and other global green systems, with the intent to monitor the features of the built environment and address issues related to human health (educational facilities pilot addenda | well v1, n.d.; the well building standard-v1, 2016). wbs is a wellknown green building assessment system that assesses educational sustainability performance and certifies health and wellbeing in the built environment (heath et al., 2018; the well building standard-v1, 2016). the wbs assesses the ieq on human health through the set of various indicators of air, light, and comfort. particularly, the wbs indicators are based on a human-centered orientation approach (educational facilities pilot addenda | well v1, n.d.; the well building standard-v1, 2016). all the existing sustainability and green rating tools differ in their structural features, such as the weighting schemes and the assessment ranking (ali & al nsairat, 2009). moreover, they take into consideration the various environmental issues and intend to promote environmental health, as well as human health and wellbeing (meiboudi et al., 2018). in this research, the wbs is chosen due to its multidisciplinary performance and its suitability to deal with health and wellness aspects. the methodological framework proposed for this study consists of three major phases: indicator selection (phase i), impact assessment (phase ii), and validation process (phase iii). the aim of phase i, indicator selection, was to reduce the number of non-practical and inefficient indicators and to maintain those which are most adequate to perform a concrete ieq assessment. although a vast number of indicators exist for the assessment of ieq performance, it is not helpful to have more and more indicators (j.-j. wang et al., 2009). on the contrary, fewer indicators may sometimes be more advantageous for evaluating the relative issues. generally, the selection of indicators requires consideration of those which are smart; that is, specific, measurable, achievable, relevant, and time-bound (ho et al., 2021; ishak et al., 2019). this phase was divided into three steps: pre-selection, filtration, and final selection. the procedure starts from the comprehensive review of wbs indicators to preselect them. regarding the filtration process, stakeholders’ opinions have been taken into account. the ieq assessment at the sustainable campus requires the comprehensive vision of different expertise in various sectors (yusoff & sulaiman, 2014). hence, multiple stakeholders in the selection of indicators should be involved who can influence or will be influenced by the recognition of objectives (dente, 2014). to this end, this study first has performed the stakeholders’ analysis employing the power-interest grid in order to identify the relevant experts in light and air sectors. afterward, a specific questionnaire was designed to select the most important indicators according to the stakeholders’ opinions. the questionnaire proposed a voting scale for the experts in relation to their preferred indicators. in the questionnaire, the authors avoided expressing any personal preferences and played only the role of analysts (løken, 2007). at this stage, in order to select the final set of indicators, the availability of data was taken into account since they should be measurable, achievable, straightforward, and cost-effective (ishak et al., 2019). in phase ii, the impact of the selected indicators was assessed. the impact assessment procedure was performed based on the literature review, technical documents investigation, focus methodology journal of sustainable architecture and civil engineering 2022/1/30 166 groups with stakeholders, data measurements, elaboration of geometric data, and in-situ analysis (torabi moghadam et al., 2018). the purpose was to measure the indicators in quantitative and qualitative ways to verify if they meet the targets defined by wbs. according to the wbs, if the evaluated indicators do not meet those targets, various health issues among the users might happen (the well building standard-v1, 2016). into this, in phase iii (validation process) a further survey has been launched to validate the primary research findings from phase ii. the survey intends to engage the students to verify which health issues are common among the students during their presence at the location considering their perceptions. moreover, their satisfaction level is evaluated through the questionnaire. furthermore, the study involved specialized doctors to verify the stated health issues by the students and identify the factors that affect their health. this is because it should consider the specialized doctors’ assessments rather than only the students’ responses to a questionnaire. table 1 shows the schematic overview of the research methodology, as described above. table 1 research methodology overview phases steps methods outputs i. in di ca to r se le ct io n pre-selection protocol review consider all wbs indicators filtration stakeholders’ analysis employing the power-interest grid select the most important indicators according to the stakeholders’ opinionslaunch of questionnaire final selection data analysis select those indicators where the data is available and measurable ii . i m pa ct a ss es sm en t data collection literature review measure the value of each indicator if they meet the targets defined by wbs technical documents investigation focus groups with stakeholders data measurements elaboration of geometric data in-situ analysis ii iva lid at io n pr oc es s students’ survey and specialized doctors’ engagement questionnaire and diagnosis involve the specialized doctors to verify the stated health issues by the students and identify the factors that affect their health verify the health issues among students and satisfaction level during their presence hours case study the polytechnic university of turin (polito) is located in the city of turin in italy, and it has a continental temperate climate. a large size classroom, ‘’classroom 1’’, located at the main campus of the polito, built-in 1958, was chosen as a case study to implement and test the proposed methodology. the ease of accessibility to the classroom to perform different in-situ analyses, the presence of sensors, and the availability of data were the main reasons to select ‘’classroom 1’’. the classroom area is about 318.11 m2 and its volume is almost 1460 m3 possessing 408 seats. the air conditioning of the classroom is supplied by an air handling unit (ahu) (noussan et al., 2017). 167 journal of sustainable architecture and civil engineering 2022/1/30 the heating, ventilation, and air conditioning (hvac) system of the classroom consists of a compressor, a condenser, an expansion valve, and an evaporator. hvac systems follow a thermodynamic process to remove heat from one place, replace it with cold air, and expel the hot air to the outside atmosphere (talei et al., 2021). they take the most power consumption to carry out the indoor environmental comfort (hamidi et al., 2021). the classroom hvac system has fig. 1 polito, campus in corso duca degli abruzzi, classroom 1. source: photo by polito data lab, october 2019 been working since 1991 and the operation hours are 8:00 am to 7:00 pm from monday to friday and from 8:00 am to 2:00 pm on saturday. the commercial building management system for hvac (desigotm) developed by siemens is the basis of the control system for the classroom (noussan et al., 2017). in the building renovation process in 2015, new automatic windows were installed. however, the window operations are not controlled by the desigotm software. the data related to the air quality (e.g., temperature, relative humidity, and co2) has been measured by the hvac system of the classroom from 2011 up to now. fig. 1 shows an interior picture of the classroom. results this section reports the results of each phase, and it discusses the significance of the findings. the outcomes obtained from the application of the methodology in the case study (classroom 1) are outlined below; phase i — indicator selection the pre-selection started from 94 indicators, which were the total indicators of wbs classified into seven categories: air, water, nourishment, light, fitness, comfort, and mind. as the case study was a classroom which is an interior part of the building, the indicators that did not have any impact on ieq were discarded, i.e., water, nourishment, mind, and fitness. at this point, the number of indicators was reduced to 50. the filtration started with the design of the specific online questionnaire to select the final set of indicators. initially, the stakeholders were identified among academic experts in the field of energy and through the interests-power grid were mapped. afterward, the online questionnaire was launched among those 80 selected stakeholders. the goal of the voting process was to identify the most significant indicators relative to the indoor air and light quality of the classroom, which can affect the health of students. by considering the opinion of all the experts in the field, it was possible to carry out a pre-selection of indicators and rate the importance of the different issues for ieq assessment. the experts were asked to answer the questions based on an ordinal scale of 0 to 4 (0 = not important to 4 = very important and dk (does not know)), in order to express their preferences. in particular, the experts rated each indicator according to three main criteria—(i) understandability, (ii) measurability, and (iii) relevancy. based on the experts’ answers, the indicators were first ranked from the most preferred to the fewer ones. then, formula (1) was employed to select the limited number of indicators (rasali et al., 2016). the average rate (x) of indicators was calculated by summing the total rates of all indicators (q) and dividing it by the total number of indicators (z). by this method, the indicators which had the total rate (y) more than the average rate (x) in each category were selected. journal of sustainable architecture and civil engineering 2022/1/30 168 q/z = x if y ≥ x → select the indicator (1) the results of the questionnaire highlighted the 12 most important indicators categorized into comfort, air, and light. they highly voted those indicators that affected the ieq issues, in terms of student health and, hence, the less important indicators were ranked at the bottom of the list. the data availability and measurability were also considered to select the final set of indicators. in this phase, the comfort category was eliminated, as the data related to its indicators were not available to be assessed. therefore, the final selection led to selecting 7 indicators. the data relating to the selected indicators were collected from the existing databases (i.e., data lab and building area) of the polito campus. table 2 shows the list of the final seven indicators and explains their objective and unit. table 2 the final set of indicators, source wbs (the well building standard-v1, 2016) category code indicator objective unit air a1 humidity control; relative humidity to provide adequate humidity levels by limiting the growth of pathogens, reducing exhaust gases, and preserving thermal comfort. % a2 smoking ban; indoor smoking ban to avoid smoking, reduce air pollution, and decrease the exposure of non-smokers to smoke. _ a3 air filtration; particle filtration to eliminate indoor and outdoor air pollution through air filtration. % light l1 daylighting fenestration; window sizes for working and learning spaces to reduce excessive radiation and make the exposure of the occupants to daylight better by increasing fenestration parameters. % l2 daylighting fenestration; window transmittance in working and learning areas to reduce excessive radiation and make the exposure of the occupant to daylight better by increasing fenestration parameters. nm l3 right to light; window access for working & learning spaces to increase occupant exposure to daylight and increase outside view by reducing the distance of workstations or desks to a window or atrium. m l4 solar glare control; daylight management to avoid sun glare by obstructing or mirroring direct sunlight from occupants. _ phase ii — impact assessment within phase ii, the impact of the final seven selected indicators was assessed for classroom 1 to explore the indoor air and light quality, and consequently, their impact on student health. table 3 summarizes how each indicator was evaluated illustrating the assessment methods (the description of how the indicator can be measured), type (quantitative vs. qualitative), and data sources (a list of resources that were used in developing the assessment of the indicators). 169 journal of sustainable architecture and civil engineering 2022/1/30 table 3 summarization of overall assessment of indicators, source (gorini et al., 2008; gualano et al., 2014; the well building standard-v1, 2016; valente et al., 2007) the upcoming part is dedicated to the assessment of indicators, which was thoroughly examined in the case study. in this part, the wbs requirements for each indicator, their assessment procedure, and evaluation results are fully described. _ indicator a1. humidity control; relative humidity (rh) requirements of wbs: according to wbs, at least one of the following is required: a an air conditioning system capable of maintaining the relative humidity between 30% and 50% during all presence hours, by reducing or increasing the humidity to the air. b the humidity level modeled in the location for at least 95% of all the working hours of the year is within 30–50%. buildings that are in humid areas are recommended to follow this feature (the well building standard-v1, 2016). assessment process: this indicator was assessed through specific measurements obtained from different networks of probes, sensors, data logs, and software. the data acquisition was achieved, at a time resolution of 15 minutes, for the whole year of 2019. the data was collected by the living lab of the polito campus, written partly in the perl script and partly in the r language, and was based on a microsoft sql server database for long-term storage. the data points related to every minute were exported into a text document and, after that, were imported into an ms sql server 2012 relational database and aggregated to a 15-minute basis. fig. 2 indicates the arrangement of rh, temperature (t) values, and their correlation in 2019. according to figure 2, the trend of changes in rh values experienced an enormous escalation from june/july/august to february/march. looking at more details, rh began at 85 % on 9/6/2019, which was the highest humidity in 2019. despite the highest value in june, the amount of rh then declined significantly and fell to the lowest rates of 10 % and 0 % on the 13th, and 20th of january and 13th of september, respectively. considering the measurements, of 11,845 rh base detections every 15 minutes, only 2833 rh detected points were within 30–50% during presence times in the year 2019 (8:00 am to 7:00 pm from monday to friday; 8:00 am to 2:00 pm on saturday). code unit assessment method type data source a1 % calculations/measurement quantitative data measured by data lab at polito campus a2 policy document/ visual inspection qualitative literature review a3 % calculations/measurement quantitative regional agency for environmental protection (arpa) piemonte, italy l1 % architectural drawing/ visual inspection quantitative/ qualitative architectural drawing documents created by building area at polito campus l2 nm architectural drawing/ architect qualitative technical office at polito campus l3 m architectural drawing/ visual inspection quantitative/ qualitative architectural drawing documents created by building area at polito campus l4 architectural drawing/ visual inspection quantitative/ qualitative architectural drawing documents created by building area at polito campus journal of sustainable architecture and civil engineering 2022/1/30 170 in addition to the rh, the air temperature was also measured by the hvac system. despite having reached a peak of 35 °c in january/february 2019, the changes in the temperature value had a period of stability from may to october (with an average of 23°c). what stands out in figure 2 is that the trend then escalated slowly from october to december 2019. the figure also illustrates the correlation between the changes of t and rh amount in 2019. with respect to the information given by the graph, the humidity values experienced a significant rise in rh from march to may 2019 with a peak of 83 % on 8/5/2019, while the temperature showed an enormous decline during that period and remained stable from 4/5/2019 to 31/10/2019. the rh then saw a significant reduction and fell to 7 % on 22/12/2019. despite fluctuating heavily between 4/1/2019 and 18/4/2019, the trend of t changed, then remained steady at 50 %. to conclude, the t values were quite stable during the period and did not change with high fluctuations, while the rh values changed rapidly. the reason for this is that the air handling unit (ahu) of the classroom measures the rh without controlling it, and the ventilation system of the classroom is obsolete; whereas the temperature of the classroom is controlled by the hvac system and the above measurement confirm the stable variations in the t values. evaluation result: according to the measurements, not all of the rh values were in the required range (30–50%), and only a few days and hours matched with the wbs requirements. _ indicator a2. smoking ban; indoor smoking ban requirements of wbs: the following building policy is required: a smoking and e-cigarettes are prohibited indoors (the well building standard-v1, 2016). assessment process: since 10 january 2005, the anti-smoking law banned smoking in all public indoor spaces in italy (gorini et al., 2008; gualano et al., 2014; valente et al., 2007). awareness of the building policy and an in-situ visualization has outlined that smoking is forbidden inside the polito campus building and classrooms. evaluation result: the smoking ban indicator for classroom 1 met the wbs requirements. _ indicator a3. air filtration; particle filtration requirements of wbs: at least one of the following requirements should be encountered in the buildings: a the filters with merv13 (or higher) are used in the air conditioning system to filter outdoor air. fig. 2 rh and t measurements at classroom 1 for 2019, source: living lab polito 171 journal of sustainable architecture and civil engineering 2022/1/30 b the pm10 and pm2.5 levels of the outdoor air measured within 1.6 km of the building for 95% of yearly hours are less than the limits indicated in the well air quality standards feature (the well building standard-v1, 2016). assessment process: this indicator was assessed by an energy simulation software, which checks all the filters located in the ventilation system of the classroom to determine the minimum efficiency rate value (merv). the calculation process was carried out considering the particle size range [nm], average minimum particle size efficiency (pse) designator (%), and fractional efficiency (%). table 4 demonstrates the results of the fractional efficiency merv calculations for the filters. table 4 fractional efficiency merv calculations particle size range[nm] fine filter #1 fine filter #2 fine filters #3 & #4 lower limit upper limit geometric mean fractional efficiency [%] average minimum pse [%] fractional efficiency [%] average minimum pse designator [%] fractional efficiency [%] average minimum pse designator [%] 300 400 346.41 78.73 87.85 80.25 89 78.18 87.06 400 550 469.04 86.36 87.72 85.79 550 700 620.48 90.89 92.49 90.51 700 1000 836.66 95.4 95.54 93.75 1000 1300 1140.18 99.6 97.69 97.18 98.22 96.43 97.10 1300 1600 1442.22 99.6 97.83 96.42 1600 2200 1876.17 98.32 98.72 97.18 2200 3000 2569.05 99.40 99.13 98.35 3000 4000 3464.10 99.60 99.83 99.30 99.60 98.60 99.20 4000 5500 4690.42 99.80 99.50 99.00 5500 7000 6204.84 99.90 99.70 99.40 7000 10000 8366.60 100 99.90 99.80 minimum efficiency reporting value (merv) merv 15 merv 15 merv 15 evaluation result: from the measurements, it was outlined that all the filters placed inside the ahu of the classroom correspond to merv 15 and the filtration system was better than the minimum required. _ indicator l1. daylighting fenestration; window sizes for working and learning spaces requirements of wbs: the following conditions should be observed in facades with regularly occupied spaces: a on the external facades, the window–wall ratio should be between 20% and 60%. if the ratio is over 40%, it requires exterior shading or tunable glazing, which is able to control unwanted heat gain and glare. b if the ratio is between 40% and 60%, the windows should be located at least 2.1 m above the floor (the well building standard-v1, 2016). journal of sustainable architecture and civil engineering 2022/1/30 172 assessment process: this indicator was assessed in three steps. in the first step, architectural drawings (dwgs) of the classroom (e.g., section, plan, and view) were utilized to measure the window and wall areas. the window–wall ratio calculations followed formula (2): (windows area/walls area) × 100 % = ratio, if ∑ ratio > 40% → windows need external shadings. (2) the classroom had a total of three exterior walls (2 walls a + 1 wall b) and 13 windows that varied in size (5 windows on each wall a + 3 windows on wall b). the results of the measurements were as follows: wall a:( windows area/walls area) × 100%, [(208×150)+(224×150)+(240×150)+(257×150)+(270×150)]÷13166.28=13% wall b:( windows area/walls area) × 100%, [(240×165)+(240×165)+(283×165)]÷646697=19%, ∑ ratio = ( 2 ratio wall a) + ratio wall b, (2×13%)+19%=45%. according to these calculations, the total window-wall ratio was about 45%. in the second step, the distances of walls and windows were measured, using the dwgs. the measurements outlined that all the windows were located 3.5 m above the floor. at the third step, an in-situ survey was implemented, which confirmed the presence of exterior blinds attached to the windows of the classroom. figure 1 shows an interior picture of the classroom, with the exterior blinds on the windows. evaluation result: according to the measurements, the window-wall ratio in classroom 1 was more than 40% and the distance of windows from the floor is more than 2.1 m. moreover, the windows had exterior shadings, and the indicator fulfilled the wbs target. _ indicator l2. daylighting fenestration; window transmittance in working and learning areas requirements of wbs: the following visible transmission (vt) conditions should be met for all non-decorative glazing: a all glazing located 2.1 m above the floor should have a vt of 60% or more. b all glazing (excluding skylights) located equal to or less than 2.1 m from the floor should have a vt of 50% or more (the well building standard-v1, 2016). assessment process: to assess this indicator, the distances between all windows and the floor were measured using the architectural drawings, and it was determined that all the windows were located 3.5 m above the floor. moreover, the technical office of the polito campus (the relevant experts) confirmed that all the glazing used in the campus building had a visible transmission (vt) of 60%. evaluation result: the indicator met the wbs requirements regarding the glazing vt conditions. _ indicator l3. right to light; window access for working and learning spaces requirements of wbs: the following conditions should be met in the buildings: 173 journal of sustainable architecture and civil engineering 2022/1/30 a the distance between 75% of workstations or desks from an atrium or a window that has e the possibility to see the outside should be 7.5 m. b the distance between 95% of all workstations from an atrium or a window that has the possibility to see the outside should be 12.5 m (the well building standard-v1, 2016). assessment process: this indicator was assessed using architectural drawings (dwgs) of the classroom to measure the distance between students’ chairs and desks from the windows. the measurements showed that 84% of desks had a 7.5 m distance from windows without views to the exterior, as the windows of the classroom were located 3.5 m above the floor and students were unable to see the outside. figure 1 shows the location of windows in the classroom. evaluation result: the indicator did not meet the wbs requirements since the windows only had the function of providing light, and there was no visual view to the outside. _ indicator l4. solar glare control; daylight management requirements of wbs: in regularly occupied spaces (excluding lobbies), if the distance between all the glazing and the floor is more than 2.1 m, at least one of the following is required: a automatic or manually controllable interior window shading, or blinds preventing excessive radiation. b automatic exterior shading systems to block excessive sunlight. c interior light shelves to reflect sunlight onto the ceiling. d a window glazing system with a micro-mirror film that reflects sunlight upwards. e a variable transparency glazing, such as electrochromic glass, can decrease the light and heat transfer by 90% or more (the well building standard-v1, 2016). indicator assessment: to assess this indicator, an onsite visualization of the classroom was implemented. in addition, the distances between windows and floors were measured, utilizing the architectural drawings (dwgs) of the classroom. the dwgs measurements indicated that windows were located 3.5 m above the floor. furthermore, an onsite survey outlined the interior blinds attached to the glazing. the blinds were controllable through an electrical component. figure 1 shows the presence of interior blinds on the windows. evaluation result: the indicator met the wbs target since the presence of blinds which were controllable through an electrical component that manually control the excessive radiation. table 5 summarizes the wbs requirements and the results of the impact assessment. over the seven indicators, five (a2, a3, l1, l2, and l4) totally met the requirements of the wbs, while the indicators a1 and l3 did not. the results obtained from the impact assessment of indicator a1 showed that the ventilation system was not working appropriately. moreover, the rh level was not between 30–50% in all of the presence hours. according to the wbs, a low level of humidity may cause health symptoms, such as skin dryness and irritation of the skin, eyes, throat, and mucous membranes. however, a high humidity level can lead to respiratory symptoms, especially in sensitive persons (the well building standard-v1, 2016). regarding indicators a2 and a3, no incompatible situation was observed in the evaluation process. as indicated previously, smoking was forbidden in the entire campus and the filtration system was in a good condition. therefore, they will probably not cause journal of sustainable architecture and civil engineering 2022/1/30 174 any health issues among the students relying on the wbs target. moreover, the window sizes and, consequently, the window–wall ratio (indicator l1) and their transmittance rate (indicator l2) were in the acceptable range. regarding indicator l3, the location of windows 3.5 m above the floor (and, thus, obviously above the heads of students) led to a lack of view to the exterior. as indicated in the wbs, having no views to the outside may cause some psychological issues for students, such as depression and distraction during the time (shamseldin, 2021; the well building standard-v1, 2016). in contrast with this issue, all the windows had exterior and interior blinds (indicator l4), which were able to control the unwanted heat and light gain to the classroom. thus, this may not cause exhaustion and discomfort among students. the primary research achievements and comparing them with wbs needed to be validated and verified whether the indicated health issues were really felt by students. into this, phase iii, as a validation process was designed. phase iii — validation process a second online survey was launched to verify the results obtained in phase ii to validate the primary research findings, regarding the health symptoms experienced by students. this survey was designed in order to compare the health issues indicated by the wbs and the real symptoms felt by students. as anticipated, the health issues indicated by the wbs due to poor air and light quality of the classroom were dryness and irritation of the skin and/or eyes, throat, mucous membranes, respiratory irritation and allergies, depression, and distraction. to this end, the questionnaire comprised four main close-ended questions, starting with a general question asking their gender as a socio-demographic variable (q1) (numata et al., 2021). the main body of the questionnaire was designed according to consider the health of students. q2 was related to the health symptoms due to the poor air quality of the classroom, while q3 asked for details of the problems caused by poor light quality. in addition, q4 evaluated the general health and satisfaction rate of the students of the classroom (prozuments et al., 2020). moreover, an open-ended question, q5, was added, which asked whether the students have any suggestions for the future improvements of indoor air and light quality of the classroom. the questionnaire is shown in table 6. category indicator code wbs requirement (the well building standard-v1, 2016) data verified air a1 the rh was between 3050% at all presence hours x a2 indoor smoking was forbidden in the classroom  a3 filters had merv 13 or higher  light l1 if window–wall ratio was between 40-60%, the external shadings were required  l2 all glazing has a vt of more than 60%  l3 the distance between 75% of students’ desks from a window which could see the outside was 7.5 m x l4 the distance between all the glazing and the floor was more than 2.1 m and the windows had blinds  table 5 data verification results for indicators 175 journal of sustainable architecture and civil engineering 2022/1/30 table 6 student health questionnaire the questionnaire was launched in december 2019, the same year of the data collection. even if the capacity of the classroom was 408 seats, during the research period (2019), only 120 students were present, and 91 students have filled in the online questionnaire. the precipitated students were composed of 35 males, 38 females, and 18 of them preferred not to say about their gender. afterward, the data was accurately analyzed and elaborated. according to the questionnaire responses, some health symptoms were almost unnoticeable among the students in the classroom, such as mucous membranes and throat, with 88 and 78 unnoticeable responses, respectively, given by the students (see fig. 3). however, dryness and irritation of the skin and eyes were reported, with 60 noticeable responses. in addition, about 58 students felt depression and only 12 students did not have any issue with distraction, while 42 of them were always distracted and 40 students were rarely distracted. fig. 3 shows the health symptoms of respondents, related to the indoor air and light quality of the classroom. dear students, this questionnaire was designed to evaluate your health and satisfaction rate about the indoor air and light quality of classroom 1 on the main campus during your presence. please answer the following questions considering your real feelings and perceptions. questions responses 1. please indicate your gender? female male prefer not to say 2. did you have any of the following health symptoms in the past 6 months? noticeable unnoticeable rarely noticeable dryness and irritation of the skin or/and eyes throat mucous membranes respiratory irritation and allergies 3. did you have any of the following psychological and neurological disorders in the past 6 months? noticeable unnoticeable rarely noticeable depression distraction 4. are you satisfied with very dissatisfied dissatisfied satisfied very satisfied lighting in the classroom? the ventilation system of the classroom? please indicate your motivation… 5. do you have any suggestions for the future indoor air and light quality improvement of the campus? if yes, please write here. journal of sustainable architecture and civil engineering 2022/1/30 176 based on 76 satisfied responses over 91, the feedback highlighted that almost all the students were satisfied with the lighting situation in the classroom, while they were not satisfied with the ventilation system (60 dissatisfaction responses). the high rate of satisfaction with the lighting system of the classroom confirmed that it was in good condition, while only 24% of students were satisfied with the ventilation system, accounting for the least number of students. fig. 4 illustrates the satisfaction rate of students related to the indoor air and light quality of the classroom. some of the students also provided their motivations for their dissatisfaction. they stated that “the air seems very dense, and we cannot breathe well, the windows are never open” and “we would like a slightly brighter light, the air in the class does not seem fresh, it’s too hot and humid”. some students suggested installing better air conditioners and also air cleaning, which will be helpful for having fresh air in the classroom. notably, students’ answers are often subjective and can be influenced by a plethora of external factors unrelated to the air and light issues. moreover, due to the fact that the life and activity of students take place inside and outside the university campus, their health is also being influenced by external factors that must be taken into account. hence, also the specialized doctors’ assessments have been considered rather than only the students’ responses to a questionnaire. fig. 3 health symptoms related to indoor air and light quality fig. 4 satisfaction rate related to indoor air and light quality of the classroom according to the analysis, the health symptoms felt by students, such as irritation and allergies, were due to inappropriate levels of rh in the classroom, as was seen in the impact assessment result for indicator a1. besides, the lack of external and natural light caused depression and distraction among a major part of students, confirming the validity of the assessment results for indicator l3. 177 journal of sustainable architecture and civil engineering 2022/1/30 the research results showed that it is important to consider and integrate all the three above-mentioned phases engaging the relevant stakeholders to measure accurately the air and light quality in an educational building. a set of indicators have been identified as the most important ones that contribute significantly to the health of students in the classroom. the impact assessment came up with two main issues, which were lastly verified by the specialized doctors. a poor level of humidity and an inappropriate position of windows in the classroom has led to the students’ health issues such as irritation and allergies, depression, and distraction. the use of assessment tools helped in defining the targets to be met and standardizing the procedure. hence, three significant insights are provided based on the key findings of the present study and interviews with experts. by doing this, the study intends to promote a high level of indoor air and light quality, in order to improve the health of students. the given insights take into account social, environmental, and economic aspects intending to aid designers to make better decisions in the design phases of the project by linking to the different sdgs, to better reflect the idea behind it. _ adapting the hvac system of the classroom: the design of hvac systems is a challenging engineering task that requires experienced decision-making (calero-pastor et al., 2017). moreover, the properties of hvac systems are very important for health purposes, and their adaption can help to reduce the risk of various infectious diseases which are transmittable by the ventilation system (chirico et al., 2020; mohammadi nafchi et al., 2021). the indoor temperature and humidity are high in a building; the virus transmission reduces. however, it is important to change the indoor air with fresh outdoor air (chipalkatti et al., 2021; haque & rahman, 2020; j. wang et al., 2020). the simulation results and relevant experts’ advice demonstrated that the hvac system of the classroom has no device to control the rh; thereby, the rh is not at an appropriate level at all during the presence hours. considering the present case study, it is quite probable that the infection risk of viruses, such as the novel coronavirus causing covid-19, could be increased during the present time, due to the inappropriate ventilation rate and rh level, especially when the rh is low. therefore, adapting the hvac system of the classroom is a vital point to improve the indoor air quality and advance the health of students. (link with sdgs 3, 4, 7, 13, 16, 11). _ using photocatalytic oxidation technology in the central ventilation system: photocatalytic oxidation technology plays an important role in human health, by purifying the indoor air. this technology has been used in various places, such as buildings materials, ventilation systems, and furniture (yu & brouwers, 2009). therefore, according to the expert opinions, using this technology in the central ventilation system of the classroom may help to remediate indoor air pollution and help to decrease possible health issues among the students. (link with sdgs 3, 4, 7, 11, 13). _ using active shading systems: active shading systems fall into three categories: integrated renewable energy shading, kinetic shading, and smart glazing (al dakheel & tabet aoul, 2017). dynamic shading systems minimize building energy consumption, balance ieq, and improve occupant visual and thermal comfort (al dakheel & tabet aoul, 2017; shamseldin, 2021). these systems fold, slide, expand, shrink, and transform in the shading devices if exposed to mechanical, chemical, or electrical drivers (al dakheel & tabet aoul, 2017). in the studied classroom, the glazing shadings were not automatic, but are manually controllable by the students through an electrical component. therefore, in the classroom, daylight could have undesirable side effects, such as unwanted heat gains and glare. in this regard, installing automatic shading devices and light sensors is vital to reduce excess heat gain and glare, thus improving the indoor light quality of the classroom, as well as student health. (link with sdgs 3,4, 7,13). discussion and future insights journal of sustainable architecture and civil engineering 2022/1/30 178 the present study addressed the need for the selection of the indicators from the green rating tool which assesses the indoor air and light quality of a campus classroom, which contributes significantly to the health of students. in this route, among various campus green rating tools, the wbs was selected due to its suitability to deal with health and wellness aspects. the set of seven indicators was selected through the comprehensive review of wbs protocol, stakeholder engagement, and data analysis. afterward, the value of each selected indicator was measured employing different assessment methods to verify if those values meet the wbs targets in terms of wellness and health of students. additionally, the health issues among students and their satisfaction level during their presence hours, have been analyzed by specialized doctors. the authors point out some of the most relevant findings of the present study which cover three points: it is crucial to engage the expert stakeholders in the process of the indicator’s selection: in fact, engaging the stakeholders led to considering different technical aspects. hence, a specific questionnaire was developed and filled out by relevant experts in the field, with the aim of selecting the most relevant indicators that mainly contribute to indoor air and light quality and, consequently, student health and wellness. the indicators need to be measured by collecting real data: after selecting the indicators, the necessary data was collected through the indicated methods shown in table 2 to assess the impacts of indicators in the specific case study. it is notable to say that there is a need to preprocess the data in order to prepare accurate, reusable, and elaborated information. the social aspects such as students’ perception should be integrated into the process: this study emphasized the importance of integrating the social aspects into the technical ones engaging the students. into this, the specific questionnaire has been distributed among the students, and consequently, their responses showed that two health symptoms were the most widespread; (i) dryness and irritation of the skin about 66%, and (ii) eye and respiratory irritation and allergies about 52 %. the students’ answers were well aligned with the out-of-range indoor air and light quality in the classroom. the used methodology is capable of being easily generalized and replicable in different similar contexts collecting the specific data and information. indeed, this flexible approach leads to a wider contribution that has been brought to the current state of the art. as a preliminary theoretical framework proposed by this study, the outcome helps designers to consider the indoor air and light quality issues from the early phase of the project with specific attention to social, institutional, and technical aspects. finally, the theoretical framework represents a substantial step towards sustainable development in the context of campus buildings. the main limitation of the present study was related to a lack of appropriate data for assessing a higher number of indicators. therefore, the indicators will need to be extended and revised through the use of specialized tools in the future with specific attention to the covid-19 situation. author contributions formal analysis, investigation, methodology, computational analysis, original draft preparation writing, graphic material elaboration, and scenario formulation: f.a.; formal analysis, investigation, computational analysis, original draft preparation, reviewing, and supervision: s.t.m.; methodology, reviewing and supervision: p.l. all authors have read and agreed to the published version of the manuscript. funding this research received no external funding. conclusions 179 journal of sustainable architecture and civil engineering 2022/1/30 acknowledgments the authors would also like to acknowledge the contributions of giovanni carioni, fabrizio tonda roc, paolo tronville, monica garis, carlo deregibus, and all the green team experts, who helped in the fulfillment of the present research results and data collection. the authors would like to also thank two anonymous reviewers for their constructive and precious comments which significantly improve this work. conflicts of interest the authors declare no conflict of interest. references abdulaali, h. s., usman, i. m. s., hanafiah, m. m., abdulhasan, m. j., hamzah, m. t., & nazal, a. 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(2021). on the built-environment quality in nearly zero-energy renovated schools: assessment and impact of passive strategies. energies, 14(10), 2799. https://doi.org/10.3390/en14102799 about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). sara torabi moghadam assistant professor interuniversity department of regional and urban studies and planning, politecnico di torino address viale mattioli 39, turin 10125, italy tel. +39 0110907438 e-mail: sara.torabi@polito.it patrizia lombardi full professor interuniversity department of regional and urban studies and planning, politecnico di torino address viale mattioli 39, turin 10125, italy tel. +39 0110907458 e-mail: patrizia.lombardi@polito.it 139 journal of sustainable architecture and civil engineering 2021/2/29 *corresponding author: jurgis.zemitis@rtu.lv a case study of thermal comfort in a temporary shelter received 2021/06/04 accepted after revision 2021/08/30 a case study of thermal comfort in a temporary shelter jsace 2/29 http://dx.doi.org/10.5755/j01.sace.29.2.29240 jurgis zemitis*, anatolijs borodinecs, raimonds bogdanovics, aleksandrs geikins riga technical university, heat, gas and water technology institute, kispalas street 6a, lv-1048, riga, latvia journal of sustainable architecture and civil engineering vol. 2 / no. 29 / 2021 pp. 139-148 doi 10.5755/j01.sace.29.2.29240 introduction in latvia to perform covid-19 tests as well as for temporary shelters in case of a local disease outbreak the persons were located in special tents. such practice was not only performed locally but also in other countries like the usa, uk, russia, etc. the wide usage of tents was possible as the outbreak happened during the warm period of the year. at the same time, the indoor climate of tents can be quite unbearable during the warm summer days. also, the situation was not getting better as fast as the prognosis, and the crisis was still ongoing during the winter period. therefore, to test the thermal comfort of such temporary shelter’s measurements were performed. the thermal comfort was measured in a tent from 27th may to 28th september 2020. the data was logged with three different measuring devices inside of the shelter as well as outside air parameters like temperature and solar radiation was logged. the results show the rapidly changing indoor temperature which reaches 40°c during the daytime and falls to 10°c at night. the data of the globe thermometer to analyze the influence of radiation from tent canvas was also studied and showed that there is no noticeable heat radiation from external walls. the pmv measurements showed that the thermal comfort is very low as the pmv values were outside the range of -1 to 1 for 57% of the time. the influence of the precipitation was also noted, and the results showed that the adiabatic cooling effect is very variable but in general does not noticeably change the indoor temperature, the average temperature decrease was only 1 °c, but for a specific case it reached 10°c. keywords: covid-19, temporary shelter, tent, thermal comfort. the year 2020 was lived in the sign of covid-19 pandemic. this affected the whole world, caused many deaths, and changed the everyday life of almost every person. as the hospitals in many countries were not capable to take up the high number of patients and at the same time ensure safe testing of inhabitants many temporary shelters were installed. in latvia to perform covid tests as well as for temporary shelters in case of a local disease outbreak the persons were located in special tents. such practice was not only performed locally but also in other countries like the usa, uk, russia, spain, italy, etc. such shelters could also be used to set up mobile vaccination points as this becomes the major weapon to fight the pandemic. also, tent-like shelters are often used in cases of refugee camps. at the end of the year, 2014 more than eight million people were living in encampments (unhcr 2014) in addition to this more than nineteen million new people were displaced due to natural hazards in 2015 (idmc 2017). by the year 2021, the number of refugees has grown to new heights and is estimated to be 26.4 million people, from whom approximately 3 million are located in europe (unhrc 2021). journal of sustainable architecture and civil engineering 2021/2/29 140 the wide usage of tents in the first month of the pandemic was possible as the outbreak started in spring and went on during the warm period of the year. at the same time, the indoor climate of tents can be quite unbearable during the warm summer days. also, the situation is not getting better as fast as anticipated and the crisis was also ongoing during the winter period and following summer. this means that some type of climatic systems must be installed for the tent-type shelters in cold climate countries to heat them during cold periods and cool during the summertime. however, it is necessary to measure the thermal comfort parameters for such a temporary shelter to see how it can be improved. thermal comfort is defined as a state of satisfaction with the thermal conditions of the environment. it is also considered as a lack of negative feelings caused by the thermal effects of the environment. assurance of thermal comfort requires the thermal stability of the human through maintenance of the thermal balance between body heat production and loss. (matusiak 2010; rupp, vásquez, and lamberts 2015; van hoof 2008; de dear et al. 2013). the thermal comfort is often expressed in pmv and ppd indices, however, the existing studies (susanti 2015; bouden and ghrab 2005; nicol, humphreys, and roaf 2012) show that in the case tents are located in a hot and humid area the results of ppd index incorrectly assess how the persons feel and pmv-ppd models have some limitations. this is backed up by a separate investigation in tianjin (yang et al. 2016). it shows that persons like soldiers and officers can adapt to the thermal environment and tolerate wider temperature fluctuations. the thermal comfort is affected by a complex interaction of various environmental aspects as well as characteristics of the tent – used materials, heating systems, location, natural ventilation options, etc. (potangaroa and hynds 2008). as thermal comfort is linked to the state of mind the stressful conditions of lockdown and pandemic could also affect the evaluation of the environment. this was studied in a paper (thapa et al. 2021) which found that the productivity and overall comfort declined with the increase in the days of lockdown, which signifies the psychological impacts of the restrictions. however, the results were not conclusive as no real environmental measurements were possible, therefore it was not possible to make further analysis of thermal comfort. also, the age of the occupants can play a role in how the thermal comfort is felt as indicated in a study (dobravalskis, šeduikyte, and didz iariekyte 2020) regarding elderly care centers and for children in daycare centers (kuusk et al. 2019). the influence of natural air infiltration must be taken into account, although this is a complex calculation a dynamic grid model method has been developed and validated in a study (bilous, deshko, and sukhodub 2020). the study established that the energy consumption of a building at the normative value of the air exchange rate and the calculated value of the natural component of the air exchange rate could differ by up to 50–75%. for thousands of years, a tent has probably been the basic form of emergency shelter. tents are relatively quick and simple to erect, they are more acceptable to host nations than more permanent forms of shelter, and remain flexible for later changes to planning or relocation (susanti 2015). however, the tents are different, with various shapes and made of specific fabrics. a study (gooijer et al. 2019) analyzed the influence of the material of tents on thermal comfort and it showed that the fabric has no influence on the heat transport at the same time it can strongly affect the water vapor transport and that the condensation cannot be prevented. in a study (obyn, van moeseke, and virgo 2015) a model was created for predicting the thermal behavior of the family shelter for emergencies used by the unhcr, the ifrc, and icrc. the results of the model were relevant and may reproduce the actual behavior of a tent, as well for belgium than for other climatic conditions. the deviation between calculated and measured internal temperatures was in ranges between 1.6°c and 2.5°c. an existing study (crawford, manfield, and mcrobie 2005) that focused on the thermal comfort of a tent located in a cold climate showed that there is a dramatic variation in temperature with height, 141 journal of sustainable architecture and civil engineering 2021/2/29 which is undesirable. also, the stratification would be a problem especially during nighttime which would lead to low temperatures and the necessity to rely on personal insulation. in theory, this could be improved by increased air mixing through ventilation. a study (rachel 2001) has also tested a liner that can be easily installed in a tent and provides good insulation and reduced heat loss. however, the stratification problem still stands, and floor insulation must be provided. another study (manfield, ashmore, and corsellis 2004) regarding tents in cold climate states that liners can have a significant effect upon improving thermal comfort inside a tent but a more holistic approach must be applied and future research should be upon how to involve displaced persons in equipping their shelter. for example, through the use of sleeping bags. a previously published paper (huang 2008) analyses six models for predicting temperature ratings of sleeping bag systems depending on the skin temperature and metabolic rate. thermal comfort through sleeping bag and clothing insulation adaption can ensure that the thermal comfort is kept even in high altitude hiking under extreme weather conditions (cena, davey, and erlandson 2003). the thermal discomfort problem occurs also during hot periods of the year. according to a study (albadra et al. 2017), the comfort temperature ranges from 17.2°c to 28.4°c if the adaptive model is applied. still, the temperature in the tents and refugee camps can be outside this range. in general, the existing tents even with improvements are not capable to ensure a pleasant indoor thermal environment (poschl 2019) and therefore must be equipped with additional hvac systems. higher comfort parameters can be achieved if the temporary shelter is developed not as a tent but as a mobile energy shelter house (kim et al. 2015), however, this is a more complex and expensive solution and is often not possible in a short period of time. in this paper, we aim to study the thermal comfort of a temporary shelter located on the 56th parallel in northern europe during the summer period. measurements of outside and indoor temperatures at various heights are performed and pmv values are calculated. the data is analyzed to see how the indoor temperature changes depending on the outside parameters such as temperature, solar radiation, and precipitation. the information is needed for further studies and for the development of a mobile modular energy unit (mmeu) which would be used to ensure pleasant indoor thermal comfort through ventilation and air cooling. methods the study was conducted from 27th may to 28th september 2020, which corresponds to the summer and early fall seasons. the measurements were done in a tent with a floor area of 54 m2 and an approximate volume of 100 m3 (see fig. 1). the studied tent was a military type. the external fabric of the tent was of dark green, waterproof pvc material with the option to add an additional cotton insulation layer. the estimated air permeability of the tent was not measured but according to existing publications (cornaro et al. 2015) could be about 35 m3/h/m2 at a pressure of 50 pa while thermal conductivity λ of the external material is 27 w/mk. the data was logged with three different measuring devices – 4 channel thermometer pce-t390 (accuracy at 23°c ±0.4% + 1°c) located in the middle of the tent at heights 0.1, 1.1, 1.8, and 2.2 m, two temperature/relative humidity loggers hobo ux100-023 (accuracy: ±0.21°c from 0° to 50°c; fig. 1 pictures of the experimental setup and ongoing measurement process fig. 2 schematic layout of the measurement setup in the tent during the experiment, the tent was kept closed and without occupants, so the air exchange was only dependent on natural causes like wind speed. at various moments, the tent was ventilated with precooled air to see how the temperature changes. the air volume for cooling purposes was 350 m3/h which was provided by ahu of a mobile modular energy unit. the temperature of the supply air was in the range of 5 to 15°c. a more detailed description of the mmeu, operational parameters and the potential energy consumption can be found in a separate publication (bogdanovics, raimonds; borodinecs, anatolijs; zemitis, jurgis; zajacs 2021). the moments when the environmental system was operating were noted and afterward, these times were excluded from the thermal comfort analysis. fig. 1 pictures of the experimental setup and ongoing measurement process fig. 2 schematic layout of the measurement setup in the tent during the experiment, the tent was kept closed and without occupants, so the air exchange was only dependent on natural causes like wind speed. at various moments, the tent was ventilated with precooled air to see how the temperature changes. the air volume for cooling purposes was 350 m3/h which was provided by ahu of a mobile modular energy unit. the temperature of the supply air was in the range of 5 to 15°c. a more detailed description of the mmeu, operational parameters and the potential energy consumption can be found in a separate publication (bogdanovics, raimonds; borodinecs, anatolijs; zemitis, jurgis; zajacs 2021). the moments when the environmental system was operating were noted and afterward, these times were excluded from the thermal comfort analysis. fig. 1 pictures of the experimental setup and ongoing measurement process fig. 2 schematic layout of the measurement setup in the tent during the experiment, the tent was kept closed and without occupants, so the air exchange was only dependent on natural causes like wind speed. at various moments, the tent was ventilated with precooled air to see how the temperature changes. the air volume for cooling purposes was 350 m3/h which was provided by ahu of a mobile modular energy unit. the temperature of the supply air was in the range of 5 to 15°c. a more detailed description of the mmeu, operational parameters and the potential energy consumption can be found in a separate publication (bogdanovics, raimonds; borodinecs, anatolijs; zemitis, jurgis; zajacs 2021). the moments when the environmental system was operating were noted and afterward, these times were excluded from the thermal comfort analysis. fig. 1 pictures of the experimental setup and ongoing measurement process fig. 2 schematic layout of the measurement setup in the tent during the experiment, the tent was kept closed and without occupants, so the air exchange was only dependent on natural causes like wind speed. at various moments, the tent was ventilated with precooled air to see how the temperature changes. the air volume for cooling purposes was 350 m3/h which was provided by ahu of a mobile modular energy unit. the temperature of the supply air was in the range of 5 to 15°c. a more detailed description of the mmeu, operational parameters and the potential energy consumption can be found in a separate publication (bogdanovics, raimonds; borodinecs, anatolijs; zemitis, jurgis; zajacs 2021). the moments when the environmental system was operating were noted and afterward, these times were excluded from the thermal comfort analysis. fig. 1 pictures of the experimental setup and ongoing measurement process journal of sustainable architecture and civil engineering 2021/2/29 142 accuracy: ±2.5% from 10% to 90% rh) placed at the two opposite corners 15 cm above floor level and 1m from walls and testo 480 with a full set of measuring probes to measure operative temperature and pmv/ppd which was placed at different locations to see the influence of radiant temperature (see fig. 2). the outside air parameters were measured using thermocouples while for solar radiation on horizontal plane gbs01 (measuring range 1400 w/m2 and accuracy ±5% plus ±50 w) was used. the data was logged with 5-minute increments. fig. 2 schematic layout of the measurement setup in the tent fig. 1 pictures of the experimental setup and ongoing measurement process fig. 2 schematic layout of the measurement setup in the tent during the experiment, the tent was kept closed and without occupants, so the air exchange was only dependent on natural causes like wind speed. at various moments, the tent was ventilated with precooled air to see how the temperature changes. the air volume for cooling purposes was 350 m3/h which was provided by ahu of a mobile modular energy unit. the temperature of the supply air was in the range of 5 to 15°c. a more detailed description of the mmeu, operational parameters and the potential energy consumption can be found in a separate publication (bogdanovics, raimonds; borodinecs, anatolijs; zemitis, jurgis; zajacs 2021). the moments when the environmental system was operating were noted and afterward, these times were excluded from the thermal comfort analysis. during the experiment, the tent was kept closed and without occupants, so the air exchange was only dependent on natural causes like wind speed. at various moments, the tent was ventilated with precooled air to see how the temperature changes. the air volume for cooling purposes was 350 m3/h which was provided by ahu of a mobile modular energy unit. the temperature of the supply air was in the range of 5 to 15°c. a more detailed description of the mmeu, operational parameters and the potential energy consumption can be found in a separate publication (bogfig. 3 left: interior of the mmeu; right: schematic of the mmeu system fig. 1 pictures of the experimental setup and ongoing measurement process fig. 2 schematic layout of the measurement setup in the tent during the experiment, the tent was kept closed and without occupants, so the air exchange was only dependent on natural causes like wind speed. at various moments, the tent was ventilated with precooled air to see how the temperature changes. the air volume for cooling purposes was 350 m3/h which was provided by ahu of a mobile modular energy unit. the temperature of the supply air was in the range of 5 to 15°c. a more detailed description of the mmeu, operational parameters and the potential energy consumption can be found in a separate publication (bogdanovics, raimonds; borodinecs, anatolijs; zemitis, jurgis; zajacs 2021). the moments when the environmental system was operating were noted and afterward, these times were excluded from the thermal comfort analysis. fig. 1 pictures of the experimental setup and ongoing measurement process fig. 2 schematic layout of the measurement setup in the tent during the experiment, the tent was kept closed and without occupants, so the air exchange was only dependent on natural causes like wind speed. at various moments, the tent was ventilated with precooled air to see how the temperature changes. the air volume for cooling purposes was 350 m3/h which was provided by ahu of a mobile modular energy unit. the temperature of the supply air was in the range of 5 to 15°c. a more detailed description of the mmeu, operational parameters and the potential energy consumption can be found in a separate publication (bogdanovics, raimonds; borodinecs, anatolijs; zemitis, jurgis; zajacs 2021). the moments when the environmental system was operating were noted and afterward, these times were excluded from the thermal comfort analysis. 143 journal of sustainable architecture and civil engineering 2021/2/29 danovics, raimonds; borodinecs, anatolijs; zemitis, jurgis; zajacs 2021). the moments when the environmental system was operating were noted and afterward, these times were excluded from the thermal comfort analysis. the results of temperature measurements in the tent at a height of 1,1m and outside air temperature can be seen in fig. 4. the data shows the temperature fluctuation during the measurement period. the white gaps without the data occur as the measurement device had to be stopped for maintenance and data reading. the absolute indoor temperature maximum in the measuring period was +41°c while the minimum +7°c. the outside temperature was in the range of +8.1°c to +29.9°c, with an average value of +18.4°c. the average indoor temperature was +21.1°c, although it seems reasonable value, the number of hours when the temperature exceeds +27°c is very high – 148 h or 20% from all the measured hours. the calculated degree hours above +27°c are 644. this means that the tent has serious overheating issues if the same approach as for buildings is applied. the usual guidelines state that the temperature should not exceed the limit temperature (+27°c) by more than 100 or 150-degree hours (°ch) in non-residential buildings, depending on the specific country. the data analysis shows that the indoor temperature rapidly rises approximately 1 h before the outside air temperature starts to rise. the calculated average temperature difference between indoor temperature and outside temp. is +2.9°c, however as the temperature evens out during the night time this value is skewed to zero. at the same time, the temperature indoors exceeds outside air temperature by more than 5°c for 522 h or 71% of the time. 10-degree difference is for 412 hours or 56% of the measurement period. results and discussion fig. 4 temperature at 1,1 m height in the middle of the tent and outside air temperature for the whole measurement period fig. 3 left: interior of the mmeu; right: schematic of the mmeu system results and discussion the results of temperature measurements in the tent at a height of 1,1m and outside air temperature can be seen in fig. 4. the data shows the temperature fluctuation during the measurement period. the white gaps without the data occur as the measurement device had to be stopped for maintenance and data reading. the absolute indoor temperature maximum in the measuring period was +41°c while the minimum +7°c. the outside temperature was in the range of +8.1°c to +29.9°c, with an average value of +18.4°c. the average indoor temperature was +21.1°c, although it seems reasonable value, the number of hours when the temperature exceeds +27°c is very high – 148 h or 20% from all the measured hours. the calculated degree hours above +27°c are 644. this means that the tent has serious overheating issues if the same approach as for buildings is applied. the usual guidelines state that the temperature should not exceed the limit temperature (+27°c) by more than 100 or 150-degree hours (°ch) in non-residential buildings, depending on the specific country. the data analysis shows that the indoor temperature rapidly rises approximately 1 h before the outside air temperature starts to rise. the calculated average temperature difference between indoor temperature and outside temp. is +2.9°c, however as the temperature evens out during the night time this value is skewed to zero. at the same time, the temperature indoors exceeds outside air temperature by more than 5°c for 522 h or 71% of the time. 10-degree difference is for 412 hours or 56% of the measurement period. fig. 4 temperature at 1,1 m height in the middle of the tent and outside air temperature for the whole measurement period for deeper data analysis and to see how the temperatures are divided depending on height see fig. 5 which shows results for june 6th. it shows all the measured indoor temperatures as well as the outside temperatures according to the official meteo.lv data, locally measured outdoor temperatures also periods of rain are marked. the minimal temperatures for all heights are similar 14.4°c but the maximal 26.5, 29.3, 32.5, 35.0°c increase with height. for deeper data analysis and to see how the temperatures are divided depending on height see fig. 5 which shows results for june 6th. it shows all the measured indoor temperatures as well as the outside temperatures according to the official meteo.lv data, locally measured outdoor temperatures also periods of rain are marked. the minimal temperatures for all heights are similar 14.4°c but the maximal 26.5, 29.3, 32.5, 35.0°c increase with height. the data analysis shows that the average temperature difference depending on the height varies throughout the day (fig. 6). during the night-time, there is no temperature gradient depending on the measurement height while in the daytime it reaches maximal values. the results show that when the temperature rises or falls it happens more rapidly closer to the ceiling. this means that the temperature closer to the floor level is more stable. the temperature fluctuations at 0.1m high at the given date are 12.1°c, while for 1.1, 1.8, and 2.2 m height 14.9, 18.1 and 20.8°c, respectively. as fig. 5 indicates that there is a temperature fall during the rain period, the data was analyzed to find the effect and whether it is linked with the rain intensity and amount. however, the available data from local meteo stations only provide data about the hourly rain intensity and does not show journal of sustainable architecture and civil engineering 2021/2/29 144 fig. 5 data of measured temperature and rain occurrence for 6th june fig. 6 temperature gradient changes depending on the height on 6th june fig. 5 data of measured temperature and rain occurrence for 6th june the data analysis shows that the average temperature difference depending on the height varies throughout the day (fig. 6). during the night-time, there is no temperature gradient depending on the measurement height while in the daytime it reaches maximal values. the results show that when the temperature rises or falls it happens more rapidly closer to the ceiling. this means that the temperature closer to the floor level is more stable. the temperature fluctuations at 0.1m high at the given date are 12.1°c, while for 1.1, 1.8, and 2.2 m height 14.9, 18.1 and 20.8°c, respectively. fig. 6 temperature gradient changes depending on the height on 6th june as fig. 5 indicates that there is a temperature fall during the rain period, the data was analyzed to find the effect and whether it is linked with the rain intensity and amount. however, the available data from local meteo stations only provide data about the hourly rain intensity and does not show the precise time of the rain period. the logged data was structured and filtered for the periods which had rain. afterward, the temperature difference which occurs during the rain period was calculated, and the respective precipitation was noted. the results are shown in fig. 7. the positive values show that the temperature decreases in a given hour, while the negative that it increases. the data are shown for indoor temperatures measured at 1,1 m height. in 11 of 19 cases, the temperature decreased. a single point stands out which shows that the temperature in a one-hour interval decreased by 10 degrees. it fig. 5 data of measured temperature and rain occurrence for 6th june the data analysis shows that the average temperature difference depending on the height varies throughout the day (fig. 6). during the night-time, there is no temperature gradient depending on the measurement height while in the daytime it reaches maximal values. the results show that when the temperature rises or falls it happens more rapidly closer to the ceiling. this means that the temperature closer to the floor level is more stable. the temperature fluctuations at 0.1m high at the given date are 12.1°c, while for 1.1, 1.8, and 2.2 m height 14.9, 18.1 and 20.8°c, respectively. fig. 6 temperature gradient changes depending on the height on 6th june as fig. 5 indicates that there is a temperature fall during the rain period, the data was analyzed to find the effect and whether it is linked with the rain intensity and amount. however, the available data from local meteo stations only provide data about the hourly rain intensity and does not show the precise time of the rain period. the logged data was structured and filtered for the periods which had rain. afterward, the temperature difference which occurs during the rain period was calculated, and the respective precipitation was noted. the results are shown in fig. 7. the positive values show that the temperature decreases in a given hour, while the negative that it increases. the data are shown for indoor temperatures measured at 1,1 m height. in 11 of 19 cases, the temperature decreased. a single point stands out which shows that the temperature in a one-hour interval decreased by 10 degrees. it the precise time of the rain period. the logged data was structured and filtered for the periods which had rain. afterward, the temperature difference which occurs during the rain period was calculated, and the respective precipitation was noted. the results are shown in fig. 7. the positive values show that the temperature decreases in a given hour, while the negative that it increases. the data are shown for indoor temperatures measured at 1,1 m height. in 11 of 19 cases, the temperature decreased. a single point stands out which shows that the temperature in a onefig. 7 change in indoor air temperature depending on precipitation rate happened during a hot summer day on june 13th when in time from 15:20 to 16:10 the temperature decreased from 31.8 to 21.8 degrees. on average the temperature decreased by only 1 degree. as the results indicate there are no direct relations between the precipitation rate and temperature change. this could be explained by the fact that the temperature is affected not only by the occurrence of rain but also by factors like outside temperature, the indoor temperature at the start of the rain, solar radiance, wind, etc. for the analysis of the results, only the cases when rain happened during the daytime (from 12:00 to 20:00) were looked at. as for the night period, the indoor temperature is already low, and the cooling effect of the rain cannot take place. fig. 7 change in indoor air temperature depending on precipitation rate the indoor air temperatures and how they change during the rain periods are shown in fig. 8. this figure in higher detail shows the adiabatic cooling effect. it can be seen that in 10 of 13 occurrences or 77 percent of rain periods the temperature, at least for some time, dropped. the information about the rain was available with a time interval of 1 hour, therefore the temperature increase could be explained by the fact that the rain lasted for a shorter amount of time, but it was not noted. fig. 8 change in indoor air temperature during the precipitation to see how the thermal comfort varies in the temporary shelter the measured predicted mean vote (pmv) was analyzed. the pmv more specifically indicates the thermal comfort of the premise than just air temperature. for the pmv calculations, it was assumed that the persons located in the tent are with a clothing level of 1 clo and activity of 1 met. fig. 9 shows the calculated pmv in the period from 2nd to 14th july. the results shown that the values for given time period the pmv value was in 145 journal of sustainable architecture and civil engineering 2021/2/29 hour interval decreased by 10 degrees. it happened during a hot summer day on june 13th when in time from 15:20 to 16:10 the temperature decreased from 31.8 to 21.8 degrees. on average the temperature decreased by only 1 degree. as the results indicate there are no direct relations between the precipitation rate and temperature change. this could be explained by the fact that the temperature is affected not only by the occurrence of rain but also by factors like outside temperature, the indoor temperature at the start of the rain, solar radiance, wind, etc. for the analysis of the results, only the cases when rain happened during the daytime (from 12:00 to 20:00) were looked at. as for the night period, the indoor temperature is already low, and the cooling effect of the rain cannot take place. the indoor air temperatures and how they change during the rain periods are shown in fig. 8. this figure in higher detail shows the adiabatic cooling effect. it can be seen that in 10 of 13 occurrences or 77 percent of rain periods the temperature, at least for some time, dropped. the information about the rain was available with a time interval of 1 hour, therefore the temperature increase could be explained by the fact that the rain lasted for a shorter amount of time, but it was not noted. fig. 8 change in indoor air temperature during the precipitation happened during a hot summer day on june 13th when in time from 15:20 to 16:10 the temperature decreased from 31.8 to 21.8 degrees. on average the temperature decreased by only 1 degree. as the results indicate there are no direct relations between the precipitation rate and temperature change. this could be explained by the fact that the temperature is affected not only by the occurrence of rain but also by factors like outside temperature, the indoor temperature at the start of the rain, solar radiance, wind, etc. for the analysis of the results, only the cases when rain happened during the daytime (from 12:00 to 20:00) were looked at. as for the night period, the indoor temperature is already low, and the cooling effect of the rain cannot take place. fig. 7 change in indoor air temperature depending on precipitation rate the indoor air temperatures and how they change during the rain periods are shown in fig. 8. this figure in higher detail shows the adiabatic cooling effect. it can be seen that in 10 of 13 occurrences or 77 percent of rain periods the temperature, at least for some time, dropped. the information about the rain was available with a time interval of 1 hour, therefore the temperature increase could be explained by the fact that the rain lasted for a shorter amount of time, but it was not noted. fig. 8 change in indoor air temperature during the precipitation to see how the thermal comfort varies in the temporary shelter the measured predicted mean vote (pmv) was analyzed. the pmv more specifically indicates the thermal comfort of the premise than just air temperature. for the pmv calculations, it was assumed that the persons located in the tent are with a clothing level of 1 clo and activity of 1 met. fig. 9 shows the calculated pmv in the period from 2nd to 14th july. the results shown that the values for given time period the pmv value was in to see how the thermal comfort varies in the temporary shelter the measured predicted mean vote (pmv) was analyzed. the pmv more specifically indicates the thermal comfort of the premise than just air temperature. for the pmv calculations, it was assumed that the persons located in the tent are with a clothing level of 1 clo and activity of 1 met. fig. 9 shows the calculated pmv in the period from 2nd to 14th july. the results shown that the values for given time period the pmv value was in divided by the ranges as follows: 2 to 3 4%; 1 to 2 12%; 0 to 1 -22%, 0 to -1 22%, -1 to -2 23%, -2 to -3 18%. this means that it was outside the reasonable range from -1 to 1 for 57% of the time. divided by the ranges as follows: 2 to 3 4%; 1 to 2 12%; 0 to 1 -22%, 0 to -1 22%, -1 to -2 23%, 2 to -3 18%. this means that it was outside the reasonable range from -1 to 1 for 57% of the time. fig. 9 values of pmv in the tent from 2nd to 14th july to see how the pmv change depending on the specific location in the tent, for some time the measuring device was placed close to the external envelope of the tent. the results are shown in fig. 10. the results show that the thermal comfort is at a very low level as for 63% of the time it is outside the range of +1 to -1. to see if the shelter envelope heats up and emits radiation to inside the globe and indoor air temperatures are compared in fig. 11. results show that the temperatures are close with an average difference of 0.5°c and maximal temperature difference +1.8°c and -1.7°c. from 907 measuring points, 715 or 79% indicate that the globe temperature is higher. fig. 10 calculated values of pmv in the tent from 19th to 23rd july fig. 11 indoor air and globe temperature in the tent from 19th to 23rd july fig. 9 values of pmv in the tent from 2nd to 14th july journal of sustainable architecture and civil engineering 2021/2/29 146 to see how the pmv change depending on the specific location in the tent, for some time the measuring device was placed close to the external envelope of the tent. the results are shown in fig. 10. the results show that the thermal comfort is at a very low level as for 63% of the time it is outside the range of +1 to -1. to see if the shelter envelope heats up and emits radiation to inside the globe and indoor air temperatures are compared in fig. 11. results show that the temperatures are close with an average difference of 0.5°c and maximal temperature difference +1.8°c and -1.7°c. from 907 measuring points, 715 or 79% indicate that the globe temperature is higher. fig. 10 calculated values of pmv in the tent from 19th to 23rd july fig. 11 indoor air and globe temperature in the tent from 19th to 23rd july divided by the ranges as follows: 2 to 3 4%; 1 to 2 12%; 0 to 1 -22%, 0 to -1 22%, -1 to -2 23%, 2 to -3 18%. this means that it was outside the reasonable range from -1 to 1 for 57% of the time. fig. 9 values of pmv in the tent from 2nd to 14th july to see how the pmv change depending on the specific location in the tent, for some time the measuring device was placed close to the external envelope of the tent. the results are shown in fig. 10. the results show that the thermal comfort is at a very low level as for 63% of the time it is outside the range of +1 to -1. to see if the shelter envelope heats up and emits radiation to inside the globe and indoor air temperatures are compared in fig. 11. results show that the temperatures are close with an average difference of 0.5°c and maximal temperature difference +1.8°c and -1.7°c. from 907 measuring points, 715 or 79% indicate that the globe temperature is higher. fig. 10 calculated values of pmv in the tent from 19th to 23rd july fig. 11 indoor air and globe temperature in the tent from 19th to 23rd july divided by the ranges as follows: 2 to 3 4%; 1 to 2 12%; 0 to 1 -22%, 0 to -1 22%, -1 to -2 23%, 2 to -3 18%. this means that it was outside the reasonable range from -1 to 1 for 57% of the time. fig. 9 values of pmv in the tent from 2nd to 14th july to see how the pmv change depending on the specific location in the tent, for some time the measuring device was placed close to the external envelope of the tent. the results are shown in fig. 10. the results show that the thermal comfort is at a very low level as for 63% of the time it is outside the range of +1 to -1. to see if the shelter envelope heats up and emits radiation to inside the globe and indoor air temperatures are compared in fig. 11. results show that the temperatures are close with an average difference of 0.5°c and maximal temperature difference +1.8°c and -1.7°c. from 907 measuring points, 715 or 79% indicate that the globe temperature is higher. fig. 10 calculated values of pmv in the tent from 19th to 23rd july fig. 11 indoor air and globe temperature in the tent from 19th to 23rd july the results of temporary shelter thermal parameter measurements show that the temperature in the tent changes rapidly during the daytime and can reach +41°c while the minimum was +7°c. the average temperature was +21.1°c. the high temperature variance between day and nighttime is due to small thermal mass as the temporary shelter is made of very light material. therefore, to maintain a comfortable indoor temperature it would be necessary both to heat and cool the shelter even during the warm period of the year. sometimes this could be overlooked in cases when a rapid need for a larger amount of temporary shelters is necessary would it be in case of pandemic, migrant crisis or any other. the difference between the temperatures at various heights during daytime reached 5.6, 5, and 6,7°c between t0,1 and t1,1, t1,1 and t1,8, t1,8 and t2,2 respectively. the maximal temperature difference between the temperature at 0,1 and 2,2 meters reached 12,7°c. this indicates about air stratification which is caused by the lack of air exchange or air movement. in the case of air mixing, it would be expected that the temperatures even out and this could be utilized to increase thermal comfort during nighttime. conclusions 147 journal of sustainable architecture and civil engineering 2021/2/29 the globe temperature analysis showed that the heat radiation from external walls does not affect the operative temperature noticeably. the average difference between the global temperature and indoor air temperature difference was only 0.5°c. the pmv study, which is based on the operative temperature as well as air velocity and relative humidity, shows that for 60% of the time the pmv value is outside the range of -1 to +1. this indicates that the tent produces very poor thermal comfort parameters. from this time pmv value was above +1 for 12% of the time and below -1 for 48% of the time. this indicates that during the night time even during the summertime persons would feel cold without an extra level of insulation. the results partially coincide with the existing studies as they also state the high ppd of persons located in temporary shelters. although these experiments were performed in indonesia and italy, countries with different climatic conditions than latvia. the study also tested the hypothesis that precipitation noticeably affects indoor temperature. the results showed that during the rain time the temperature decreases for 77 percent of rain occurrences. the influence on temperature is noticeable and, in most cases, close to 5°c. however, the temperature change was not related to the precipitation amount. also, the average temperature decrease was only 1°c±2.96, but for a specific case, even a 10°c decrease was reached. the study is limited by the fact that in a real case scenario the temporary shelter would be occupied by persons. this would influence the door opening and therefore the air circulation in the tent. due to this, the expected indoor temperatures would be lower during the daytime. as for the nighttime, the indoor temperature should be higher in the case of persons using it, as they would be emitting heat from their bodies. the study regarding the temperature drop caused by precipitation should also be continued and improved, as during the measurement period there was a small number (13) of rain occurrences during the daytime. for future studies thermal comfort of temporary shelter equipped with mmeu could be carried out, to study the impact of such a device and its potential to increase thermal comfort. acknowledgment this work has been supported by the european regional development fund within the activity 1.1.1.2 “post-doctoral research aid” of the specific aid objective 1.1.1 “to increase the research and innovative capacity of scientific institutions of latvia and the ability to attract external financing, investing in human resources and infrastructure” of the operational programme “growth and employment” (no. 1.1.1.2/viaa/1/16/033). references albadra, d., m. vellei, d. coley, and j. hart. 2017. “thermal comfort in desert refugee camps: an interdisciplinary approach.” building and environment 124. https://doi.org/10.1016/j.buildenv.2017.08.016 bilous, i. yu, v. i. deshko, and i. o. sukhodub. 2020. “building energy modeling using hourly infiltration rate.” magazine of 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www.unhcr.org/statisticalyearbook/2014-annex-tables.zip. unhrc. 2021. “refugee data finder.” 2021. https:// www.unhcr.org/refugee-statistics/. yang, hao, yingni jiang, jingbo liu, and zhengguo gong. 2016. “the field investigation on thermal comfort of tent in early autumn of tianjin.” matec web of conferences 61: 2-5. https://doi. org/10.1051/matecconf/20166101001 149 journal of sustainable architecture and civil engineering 2021/2/29 jurgis zemitis associate professor riga technical university, heat, gas and water technology institute main research area energy performance of buildings, ventilation, heating address kispalas street 6a, lv1048, riga, latvia tel.+ 371 28369940 e-mail: jurgis.zemitis@ rtu.lv anatolijs borodinecs professor riga technical university, heat, gas and water technology institute main research area energy performance of buildings, hvac systems, thermal bridges address kispalas street 6a, lv1048, riga, latvia tel.+ 371 26079655 e-mail: anatolijs. borodinecs@rtu.lv raimonds bogdanovics researcher riga technical university, heat, gas and water technology institute main research area energy performance of buildings, centralized heating systems, renewable resources address kispalas street 6a, lv1048, riga, latvia tel.+ 371 25450508 e-mail: raimonds. bogdanovics@rtu.lv aleksandrs geikins researcher riga technical university, heat, gas and water technology institute main research area energy performance of buildings, hvac systems address kispalas street 6a, lv1048, riga, latvia tel.+ 371 27262222 e-mail: aleksandrs. geikins@rtu.lv about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 83 journal of sustainable architecture and civil engineering 2014/4/9 jsace 4/9 journal of sustainable architecture and civil engineering vol. 4 / no. 9 / 2014 pp. 83-90 doi 10.5755/j01.sace.9.4.7129 © kaunas university of technology received 2014/05/16 accepted after revision 2014/09/01 numerical simulation of a site response analysis with strata software ana nicuţă, alexandra alisa găină* “gheorghe asachi” technical university, faculty of civil engineering and building services 43 d. mangeron, 700050 iași, romania *corresponding author: alisa.gaina@yahoo.com numerical simulation of a site response analysis with strata software http://dx.doi.org/10.5755/j01.sace.9.4.7129 the analysis of the ground foundation must take into consideration two main aspects: a simulation of the ground motion as close as possible to reality and the correlation of the ground motion with existing geological conditions. thus, it can be distinguished two main functions of the soils: the function of a dynamic filter for the seismic movement that come from the source, and the function of a deformable spring for the buildings whose support is. in this paper, the behavior of a site was analyzed from the site response point of view, using different accelerograms of romanian’s earthquake. these accelerograms were recorded during the 1977, 1986 and 1990 earthquakes. in order to perform equivalent linear site response analysis we use the strata software for a homogeneous soil layer with more than 10 meters depth. the soil type and the velocity layering were considered constant on the entire soil deposit. the analysis was done both on cohesive and cohesionless soils. the final results have been mapped in terms of soil dynamic characteristics, accelerograms and acceleration response spectrum, under different earthquake excitations. keywords: accelerograms, earthquake, site response, soil dynamic, strata. romania is one of the european countries with intense seismic activity. over the time, the country was shaken by several earthquakes, the majority of them having the epicentral in vrancea, by far the most seismically active zone of romania (vlad and vlad 2008). three major earthquakes that occurred in vrancea had a considerable impact both on the population and on the buildings. these earthquakes are: march 4, 1977 vrancea earthquake with m g-r = 7.2 magnitude (pomonis, coburn and ledbetter 1990), being the first strong seismic motion recorded in romania, august 31, 1986 with m g-r = 7.0 magnitude and may 30, 1990 (m g-r = 6.7), and may 31, 1990 (m g-r = 6.1) (balan et al. 1983, sokolov, boese and wenyel 2008, vlad and vlad 2008). march 4, 1977 earthquake is considered to be, because of its effects, one of the most devastating seismic shocks occurred in romania. there were recorded victims and important material loss, especially in the urban centres with high population density and constructions, the majority of them in the south country. the reinstatement in exploitation conditions of the building, as soon as possible, involved high financial efforts. after 1986 and 1990 earthquake no material damage introduction journal of sustainable architecture and civil engineering 2014/4/9 84 and victims were recorded. due to this records obtained during this earthquakes it was possible to define the main characteristics of the romania seismicity and to draw seismic maps with acceleration distribution for the entire territory. concerns regarding anti-seismic insurance appeared with the population growth centres in seismic areas, with the increase in volume and height of the important constructions. the prevention of urban centres decline and reduction of the city expansion are current issues in many states. in order to prevent the occupation of new sites, the engineers have as principal purpose to increase the building’s service life through flexibility and adaptability, and to renovate the existing buildings with design to grow their lifetime (mahin 2008). because of these aspects mentioned above, it is required to take into consideration, in designing a new building, the impact on the environment. the concept of sustainable design or so-called green buildings is based on lower consumption and protection of the environment. this concept applied on earthquake engineering design implies other aspects like durability, longevity, efficient design methods and efficient structural methods. recently, on the romanian territory large numbers of earthquakes was recorded with small and moderate intensity. this high seismic activity, which in a first stage induces a positive effect on the compaction of the ground surface, can also have negative effects regarding the subsequent stresses and strains, which affect primarily the mechanical characteristics, thus their resistance. therefore, the necessity of knowing the behaviour of the soil subjected to dynamic loads is required under the conditions mentioned above. the present paper aims to develop a numerical simulation of horizontally layered soil deposits (cohesive and cohesionless), to a depth up to 100 m, in order to evaluate soil effects under different earthquake excitations. an equivalent linear site response analysis is performed by using strata software. in romania, the design of structures for earthquake excitation is based on eurocode 8 and romanian designing code p100/2013. these norms give some general elements regarding the seismic effects on sites recorded during the time. in relation to the average shear waves in the first 30 m, according with ec 8 first part, the soils are classified in five categories a, b, c, d and e (eurocode 8 1998) for the response spectrum analysis of a site it is necessary to highlight the dynamic characteristics of the studied soil, namely stiffness and material damping. soil stiffness is characterized by wave velocity (v s ) or shear modulus (g) (zhang, andrus and juang 2005). through previous studies were able to estimate the dynamic soil properties (g/g max variation and d with γ) both for sandy and clayey soils (ishibashi and zhang 1993). estimation of the shear modulus and damping curves may be obtained from laboratory measurements a soil samples or derived from empirical models based on soil type and other variables (kottke and rathje 2009). there are some empirical model developed by richard et al. 1970, seed and idriss 1970, hardin and drnevich 1972, zen et al. 1978, gei 1983, seed et al. 1986, sun et al. 1988, geomatrix 1990, vaucetic and dobry 1991, epri 1993, darendeli and stokoe 2001, etc. (jafarian, haddad and javdanian 2014, kottke and rathje 2009, zhang, andrus and juang 2005) the main factors that influence g/g max and d are: confining pressure (σ’ m ) plasticity index (pi), over consolidation ratio (ocr), frequency (f) and number of cycles of loading (n) (bahar, saci, louadj and vicens 2012). in general, the evaluation of the dynamic soil properties are made by means of “in situ” tests (down-hole, up-hole, cross-hole, dynamic penetration, spectral analysis of surface waves) or laboratory tests (resonant column, cyclic simple shear, cyclic torsional shear and cyclic triaxial). input data for the site response analysis 85 journal of sustainable architecture and civil engineering 2014/4/9 in this paper, for the analysis of the seismic site response it was used the characteristic curves proposed by idriss (1990) for sands and clays. the carried out simulations took into consideration physical and mechanical characteristics of the romanian’s soils. the numerical simulations were performed by using strata software. due to the variation of the shear deformation and seismic motion intensity, both for the cohesive and cohesionless soils, for the studied soil deposit it was performed an equivalent linear site depth [m] cohesionless soil (sand) cohesive soil (clay) unit weight γ [kn/m3] v s [m/s] unit weight γ [kn/m3] v s [m/s] 0-5 17.5 50 18.5 150 5-30 18.0 100 18.5 200 30-50 18.0 150 19.0 300 50-70 18.5 200 19.5 400 bedrock 22.0 750 22.0 750 table 1 minimum element thicknesses (mm) for typical fire resistance periods (minutes) (nsai, 2005) earthquake year pga (m/s2) pgv (m/s) pgd (m) 4 martie 1977 1.949 0.719 1.631 31 august 1986 0.838 0.075 0.014 30 mai 1990 0.662 0.064 0.011 table 2 characteristics values of the accelerograms recorded in 1977, 1986 and 1990 on n-s direction response analysis. according to the soil type and stratigraphy, it was introduced in the program, as input values, a number of average characteristics of the soil deposit depending on its physical state, highlighted in table 1. the input motions defined in the program are represented by the accelerograms of 1977, 1986 and 1990 earthquake, recorded by the seismic station of incerc bucharest. in the program it was considered those accelerograms recorded on the n-s direction of the earthquake motion. in table 2 the main characteristics of the accelerograms defined in the program are presented. the location of the input motion is considered to be at the top of the bedrock. seed and idriss (1970) introduced for the first time the equivalent-linear analysis approach, being a referenced point for the subsequent researches (matosovic and hashash 2012). in order to evaluate the soils from the site response analysis point of view, it has been considered, as output data, for both cohesive and cohesionless soil deposit, the following results after running strata software: damping ratio, shear modulus profile, spectral ratio, accelerations response spectrum at the surface and at the bedrock. in the graphic representations it was used the following notations: case 1 for the 1977 acceleration data, case 2 for 1986 acceleration data and case 3 for 1990 acceleration data. results and discussions 2. input data for the site response analysis in romania, the design of structures for earthquake excitation is based on eurocode 8 and romanian designing code p100/2013. these norms give some general elements regarding the seismic effects on sites recorded during the time. in relation to the average shear waves in the first 30 m, according with ec 8 first part, the soils are classified in five categories a, b, c, d and e (eurocode 8 1998) for the response spectrum analysis of a site it is necessary to highlight the dynamic characteristics of the studied soil, namely stiffness and material damping. soil stiffness is characterized by wave velocity (v s ) or shear modulus (g) (zhang, andrus and juang 2005). through previous studies were able to estimate the dynamic soil properties (g/g max variation and d with γ) both for sandy and clayey soils (ishibashi and zhang 1993). estimation of the shear modulus and damping curves may be obtained from laboratory measurements a soil samples or derived from empirical models based on soil type and other variables (kottke and rathje 2009). there are some empirical model developed by richard et al. 1970, seed and idriss 1970, hardin and drnevich 1972, zen et al. 1978, gei 1983, seed et al. 1986, sun et al. 1988, geomatrix 1990, vaucetic and dobry 1991, epri 1993, darendeli and stokoe 2001, etc. (jafarian, haddad and javdanian 2014, kottke and rathje 2009, zhang, andrus and juang 2005) the main factors that influence g/g max and d are: confining pressure (σ’ m ) plasticity index (pi), over consolidation ratio (ocr), frequency (f) and number of cycles of loading (n) (bahar, saci, louadj and vicens 2012). in general, the evaluation of the dynamic soil properties are made by means of “in situ” tests (down-hole, up-hole, cross-hole, dynamic penetration, spectral analysis of surface waves) or laboratory tests (resonant column, cyclic simple shear, cyclic torsional shear and cyclic triaxial). in this paper, for the analysis of the seismic site response it was used the characteristic curves proposed by idriss (1990) for sands and clays. the carried out simulations took into consideration physical and mechanical characteristics of the romanian’s soils. the numerical simulations were performed by using strata software. due to the variation of the shear deformation and seismic motion intensity, both for the cohesive and cohesionless soils, for the studied soil deposit it was performed an equivalent linear site response analysis. according to the soil type and stratigraphy, it was introduced in the program, as input values, a number of average characteristics of the soil deposit depending on its physical state, highlighted in table 1. table 1. soil profile for sand and clay deposit depth [m] cohesionless soil (sand) cohesive soil (clay) unit weight γ [kn/m 3 ] v s [m/s] unit weight γ [kn/m 3 ] v s [m/s] 0-5 17.5 50 18.5 150 5-30 18.0 100 18.5 200 30-50 18.0 150 19.0 300 50-70 18.5 200 19.5 400 bedrock 22.0 750 22.0 750 the input motions defined in the program are represented by the accelerograms of 1977, 1986 and 1990 earthquake, recorded by the seismic station of incerc bucharest. in the program it was considered those accelerograms recorded on the n-s direction of the earthquake motion. in table 2 the main characteristics of the accelerograms defined in the program are presented. the location of the input motion is considered to be at the top of the bedrock. table 2. characteristics values of the accelerograms recorded in 1977, 1986 and 1990 on n-s direction earthquake year pga (m/s 2 ) pgv (m/s) pgd (m) 4 martie 1977 1.949 0.719 1.631 31 august 1986 0.838 0.075 0.014 30 mai 1990 0.662 0.064 0.011 3. results and discussions seed and idriss (1970) introduced for the first time the equivalent-linear analysis approach, being a referenced point for the subsequent researches (matosovic and hashash 2012). in order to evaluate the soils from the site response analysis point of view, it has been considered, as output data, for both cohesive and cohesionless soil deposit, the following results after running strata software: damping ratio, shear modulus profile, spectral ratio, accelerations response spectrum at the surface and at the bedrock. in the graphic representations it was used the following notations: case 1 for the 1977 acceleration data, case 2 for 1986 acceleration data and case 3 for 1990 acceleration data. 3.1. results obtained for the cohesive soil deposit according to the idriss (1990) empirical model for clays it was possible to evaluate, using strata software, the degradation of the shear modulus and damping ratio curves for a cohesive deposit soil, presented in fig. 1 and fig. 2. fig. 1. variation of damping ratio (d) under different earthquake excitations (cohesive soil) case 3 case 2 case 1 minimum average maximum fig. 1 variation of damping ratio (d) under different earthquake excitations (cohesive soil) journal of sustainable architecture and civil engineering 2014/4/9 86 fig. 2. degradation of shear modulus (g) under different earthquake excitations (cohesive soil) it can be noted that, the most unfavorable behavior of the shear modulus and damping ratio (fig. 1 and fig. 2) is the one in which it was used as input ground motion 1977 earthquake accelerogram. fig. 3. maximum shear-strain for different earthquake excitations (cohesive soil) furthermore, in fig. 3 it can be observed that the degradation curve of the cohesive soil is bigger in the first case than in the others, a fact that confirms the statements mentioned above. the median value of shear-strain is equal with 0.046% at 100 m depth. fig. 4. spectral ratio between surface and bedrock (cohesive soil) fig. 4 shows spectral ratio between surface and bedrock for the considered layer of cohesive soil deposit in relation with the maximum, minimum and average values. the main parameters that influence the site response are input ground motions, wave velocity profile and material nonlinearity (matosovic and hashash 2012, graizer 2011, luke and liu 2008). these parameters are expressed by the acceleration response spectrum in order to determine a site response analysis it is necessary to determine the acceleration response spectrum at the surface and at the bedrock. thus, in fig. 5 and fig. 6 the acceleration response spectrum for the three considered cases are compared. fig. 5. acceleration response spectrum at the surface (cohesive soil) the maximum acceleration that corresponds to the first case, having the value as max =1.043 g, compared to the second and third case, where as max is 0.466 g and 0.387 g, respectively. these values are specific to the acceleration response spectrum at the surface (fig. 5). case 1 case 2 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 case 1 case 2 case 3 minimum average maximum minimum average maximum case 1 case 2 case 3 the median value of shear-strain is equal with 0.046% at 100 m depth. fig. 4 shows spectral ratio between surface and bedrock for the considered layer of cohesive soil deposit in relation with the maximum, minimum and average values. the main parameters that influence the site response are input ground motions, wave velocity profile and material nonlinearity (matosovic and hashash 2012, graizer 2011, luke and liu 2008). fig. 4 spectral ratio between surface and bedrock (cohesive soil) results obtained for the cohesive soil deposit according to the idriss (1990) empirical model for clays it was possible to evaluate, using strata software, the degradation of the shear modulus and damping ratio curves for a cohesive deposit soil, presented in fig. 1 and fig. 2. it can be noted that, the most unfavorable behavior of the shear modulus and damping ratio (fig. 1 and fig. 2) is the one in which it was used as input ground motion 1977 earthquake accelerogram. furthermore, in fig. 3 it can be observed that the degradation curve of the cohesive soil is bigger in the first case than in the others, a fact that confirms the statements mentioned above. fig. 2. degradation of shear modulus (g) under different earthquake excitations (cohesive soil) it can be noted that, the most unfavorable behavior of the shear modulus and damping ratio (fig. 1 and fig. 2) is the one in which it was used as input ground motion 1977 earthquake accelerogram. fig. 3. maximum shear-strain for different earthquake excitations (cohesive soil) furthermore, in fig. 3 it can be observed that the degradation curve of the cohesive soil is bigger in the first case than in the others, a fact that confirms the statements mentioned above. the median value of shear-strain is equal with 0.046% at 100 m depth. fig. 4. spectral ratio between surface and bedrock (cohesive soil) fig. 4 shows spectral ratio between surface and bedrock for the considered layer of cohesive soil deposit in relation with the maximum, minimum and average values. the main parameters that influence the site response are input ground motions, wave velocity profile and material nonlinearity (matosovic and hashash 2012, graizer 2011, luke and liu 2008). these parameters are expressed by the acceleration response spectrum in order to determine a site response analysis it is necessary to determine the acceleration response spectrum at the surface and at the bedrock. thus, in fig. 5 and fig. 6 the acceleration response spectrum for the three considered cases are compared. fig. 5. acceleration response spectrum at the surface (cohesive soil) the maximum acceleration that corresponds to the first case, having the value as max =1.043 g, compared to the second and third case, where as max is 0.466 g and 0.387 g, respectively. these values are specific to the acceleration response spectrum at the surface (fig. 5). case 1 case 2 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 case 1 case 2 case 3 minimum average maximum minimum average maximum case 1 case 2 case 3 fig. 2. degradation of shear modulus (g) under different earthquake excitations (cohesive soil) it can be noted that, the most unfavorable behavior of the shear modulus and damping ratio (fig. 1 and fig. 2) is the one in which it was used as input ground motion 1977 earthquake accelerogram. fig. 3. maximum shear-strain for different earthquake excitations (cohesive soil) furthermore, in fig. 3 it can be observed that the degradation curve of the cohesive soil is bigger in the first case than in the others, a fact that confirms the statements mentioned above. the median value of shear-strain is equal with 0.046% at 100 m depth. fig. 4. spectral ratio between surface and bedrock (cohesive soil) fig. 4 shows spectral ratio between surface and bedrock for the considered layer of cohesive soil deposit in relation with the maximum, minimum and average values. the main parameters that influence the site response are input ground motions, wave velocity profile and material nonlinearity (matosovic and hashash 2012, graizer 2011, luke and liu 2008). these parameters are expressed by the acceleration response spectrum in order to determine a site response analysis it is necessary to determine the acceleration response spectrum at the surface and at the bedrock. thus, in fig. 5 and fig. 6 the acceleration response spectrum for the three considered cases are compared. fig. 5. acceleration response spectrum at the surface (cohesive soil) the maximum acceleration that corresponds to the first case, having the value as max =1.043 g, compared to the second and third case, where as max is 0.466 g and 0.387 g, respectively. these values are specific to the acceleration response spectrum at the surface (fig. 5). case 1 case 2 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 case 1 case 2 case 3 minimum average maximum minimum average maximum case 1 case 2 case 3 fig. 2 variation of damping ratio (d) under different earthquake excitations (cohesive soil) fig. 3 maximum shear-strain for different earthquake excitations (cohesive soil) 2 3 87 journal of sustainable architecture and civil engineering 2014/4/9 fig. 2. degradation of shear modulus (g) under different earthquake excitations (cohesive soil) it can be noted that, the most unfavorable behavior of the shear modulus and damping ratio (fig. 1 and fig. 2) is the one in which it was used as input ground motion 1977 earthquake accelerogram. fig. 3. maximum shear-strain for different earthquake excitations (cohesive soil) furthermore, in fig. 3 it can be observed that the degradation curve of the cohesive soil is bigger in the first case than in the others, a fact that confirms the statements mentioned above. the median value of shear-strain is equal with 0.046% at 100 m depth. fig. 4. spectral ratio between surface and bedrock (cohesive soil) fig. 4 shows spectral ratio between surface and bedrock for the considered layer of cohesive soil deposit in relation with the maximum, minimum and average values. the main parameters that influence the site response are input ground motions, wave velocity profile and material nonlinearity (matosovic and hashash 2012, graizer 2011, luke and liu 2008). these parameters are expressed by the acceleration response spectrum in order to determine a site response analysis it is necessary to determine the acceleration response spectrum at the surface and at the bedrock. thus, in fig. 5 and fig. 6 the acceleration response spectrum for the three considered cases are compared. fig. 5. acceleration response spectrum at the surface (cohesive soil) the maximum acceleration that corresponds to the first case, having the value as max =1.043 g, compared to the second and third case, where as max is 0.466 g and 0.387 g, respectively. these values are specific to the acceleration response spectrum at the surface (fig. 5). case 1 case 2 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 case 1 case 2 case 3 minimum average maximum minimum average maximum case 1 case 2 case 3 fig. 6. acceleration response spectrum at the bedrock (cohesive soil) the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 6 are: as max =0.631 g for 1977 earthquake, as max = 0.409 g, for 1986 and as max =0.408 g for 1990. 3.2. results obtained for the cohesionless deposit as in the first case, an evaluation of the shear modulus and damping ratio curves was done, but in this situation for a cohesionless soil deposit, using the idriss (1990) empirical model for sands. fig. 7. damping ratio (d) profile under different earthquake excitations (cohesionless soil) fig. 8. degradation of shear modulus (g) under different earthquake excitations (cohesionless soil) according to the fig. 7 and fig. 8, also for the noncohesive soil, it was observed that the most unfavorable results correspond to the first case. in the first case, spectral ratio has a minimum variation in relation with the average value of the three considered cases (fig. 9). the median value of shear-strain is equal with 0.108% at 100 m depth (fig. 10). fig. 9. spectral ratio between surface and bedrock (cohesionless soil) case 3 case 2 case 1 minimum average maximum case 3 case 2 case 1 minimum average maximum case 1 case 2 case 3 minimum average maximum case 3 case 2 case 1 maximum average minimum fig. 6. acceleration response spectrum at the bedrock (cohesive soil) the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 6 are: as max =0.631 g for 1977 earthquake, as max = 0.409 g, for 1986 and as max =0.408 g for 1990. 3.2. results obtained for the cohesionless deposit as in the first case, an evaluation of the shear modulus and damping ratio curves was done, but in this situation for a cohesionless soil deposit, using the idriss (1990) empirical model for sands. fig. 7. damping ratio (d) profile under different earthquake excitations (cohesionless soil) fig. 8. degradation of shear modulus (g) under different earthquake excitations (cohesionless soil) according to the fig. 7 and fig. 8, also for the noncohesive soil, it was observed that the most unfavorable results correspond to the first case. in the first case, spectral ratio has a minimum variation in relation with the average value of the three considered cases (fig. 9). the median value of shear-strain is equal with 0.108% at 100 m depth (fig. 10). fig. 9. spectral ratio between surface and bedrock (cohesionless soil) case 3 case 2 case 1 minimum average maximum case 3 case 2 case 1 minimum average maximum case 1 case 2 case 3 minimum average maximum case 3 case 2 case 1 maximum average minimum fig. 6. acceleration response spectrum at the bedrock (cohesive soil) the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 6 are: as max =0.631 g for 1977 earthquake, as max = 0.409 g, for 1986 and as max =0.408 g for 1990. 3.2. results obtained for the cohesionless deposit as in the first case, an evaluation of the shear modulus and damping ratio curves was done, but in this situation for a cohesionless soil deposit, using the idriss (1990) empirical model for sands. fig. 7. damping ratio (d) profile under different earthquake excitations (cohesionless soil) fig. 8. degradation of shear modulus (g) under different earthquake excitations (cohesionless soil) according to the fig. 7 and fig. 8, also for the noncohesive soil, it was observed that the most unfavorable results correspond to the first case. in the first case, spectral ratio has a minimum variation in relation with the average value of the three considered cases (fig. 9). the median value of shear-strain is equal with 0.108% at 100 m depth (fig. 10). fig. 9. spectral ratio between surface and bedrock (cohesionless soil) case 3 case 2 case 1 minimum average maximum case 3 case 2 case 1 minimum average maximum case 1 case 2 case 3 minimum average maximum case 3 case 2 case 1 maximum average minimum these parameters are expressed by the acceleration response spectrum in order to determine a site response analysis it is necessary to determine the acceleration response spectrum at the surface and at the bedrock. thus, in fig. 5 and fig. 6 the acceleration response spectrum for the three considered cases are compared. the maximum acceleration that corresponds to the first case, having the value as max =1.043 g, compared to the second and third case, where as max is 0.466 g and 0.387 g, respectively. these values are specific to the acceleration response spectrum at the surface (fig. 5). the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 6 are: as max =0.631 g for 1977 earthquake, as max = 0.409 g, for 1986 and as max =0.408 g for 1990. fig. 5 acceleration response spectrum at the surface (cohesive soil) fig. 7 damping ratio (d) profile under different earthquake excitations (cohesionless soil) fig. 8 degradation of shear modulus (g) under different earthquake excitations (cohesionless soil) fig. 6 acceleration response spectrum at the bedrock (cohesive soil) results obtained for the cohesionless deposit as in the first case, an evaluation of the shear modulus and damping ratio curves was done, but in this situation for a cohesionless soil deposit, using the idriss (1990) empirical model for sands. according to the fig. 7 and fig. 8, also for the non-cohesive soil, it was observed that the most 5 7 6 8 journal of sustainable architecture and civil engineering 2014/4/9 88 unfavorable results correspond to the first case. in the first case, spectral ratio has a minimum variation in relation with the average value of the three considered cases (fig. 9). the median value of shear-strain is equal with 0.108% at 100 m depth (fig. 10). compared to the cohesive soil deposit, the maximum value of acceleration response spectrum for non-cohesive soil corresponds to the second case, having the value of as max = 0.434 g (fig. 11). the values for the second case and third case are 0.278 g and 0.246 g, respectively. it can be also noticed that the values of spectral accelerations are lower compared to the cohesive soil. the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 12 are: as max =0.626 g for 1977 earthquake, as max = 0.408 g, for 1986 and as max =0.411 g for 1990. in fig. 13, fig. 14 and fig. 15 the acceleration data recorded at the surface with the software strata for a cohesive soil deposit are represented. fig. 6. acceleration response spectrum at the bedrock (cohesive soil) the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 6 are: as max =0.631 g for 1977 earthquake, as max = 0.409 g, for 1986 and as max =0.408 g for 1990. 3.2. results obtained for the cohesionless deposit as in the first case, an evaluation of the shear modulus and damping ratio curves was done, but in this situation for a cohesionless soil deposit, using the idriss (1990) empirical model for sands. fig. 7. damping ratio (d) profile under different earthquake excitations (cohesionless soil) fig. 8. degradation of shear modulus (g) under different earthquake excitations (cohesionless soil) according to the fig. 7 and fig. 8, also for the noncohesive soil, it was observed that the most unfavorable results correspond to the first case. in the first case, spectral ratio has a minimum variation in relation with the average value of the three considered cases (fig. 9). the median value of shear-strain is equal with 0.108% at 100 m depth (fig. 10). fig. 9. spectral ratio between surface and bedrock (cohesionless soil) case 3 case 2 case 1 minimum average maximum case 3 case 2 case 1 minimum average maximum case 1 case 2 case 3 minimum average maximum case 3 case 2 case 1 maximum average minimum fig. 10. maximum shear-strain for different earthquake excitations (cohesionless soil) compared to the cohesive soil deposit, the maximum value of acceleration response spectrum for non-cohesive soil corresponds to the second case, having the value of as max = 0.434 g (fig. 11). the values for the second case and third case are 0.278 g and 0.246 g, respectively. it can be also noticed that the values of spectral accelerations are lower compared to the cohesive soil. the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 12 are: as max =0.626 g for 1977 earthquake, as max = 0.408 g, for 1986 and as max =0.411 g for 1990. fig. 11. acceleration response spectrum at the surface (cohesionless soil) fig. 12. acceleration response spectrum at the bedrock (cohesionless soil) in fig. 13, fig. 14 and fig. 15 the acceleration data recorded at the surface with the software strata for a cohesive soil deposit are represented. in fig. 16, fig. 17 and fig. 18 the acceleration data recorded at the surface with the software strata for a cohesionless soil deposit are represented. fig. 13. acceleration of 4 march, 1977 earthquake at the surface, direction ns –strata (cohesive soil) fig. 14. acceleration of 31 august, 1986 earthquake at the surface, direction ns – strata (cohesive soil) minimum average maximum case 3 case 2 case 1 case 2 case 1 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 fig. 9 spectral ratio between surface and bedrock (cohesionless soil) fig. 10 maximum shear-strain for different earthquake excitations (cohesionless soil) 9 10 fig. 10. maximum shear-strain for different earthquake excitations (cohesionless soil) compared to the cohesive soil deposit, the maximum value of acceleration response spectrum for non-cohesive soil corresponds to the second case, having the value of as max = 0.434 g (fig. 11). the values for the second case and third case are 0.278 g and 0.246 g, respectively. it can be also noticed that the values of spectral accelerations are lower compared to the cohesive soil. the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 12 are: as max =0.626 g for 1977 earthquake, as max = 0.408 g, for 1986 and as max =0.411 g for 1990. fig. 11. acceleration response spectrum at the surface (cohesionless soil) fig. 12. acceleration response spectrum at the bedrock (cohesionless soil) in fig. 13, fig. 14 and fig. 15 the acceleration data recorded at the surface with the software strata for a cohesive soil deposit are represented. in fig. 16, fig. 17 and fig. 18 the acceleration data recorded at the surface with the software strata for a cohesionless soil deposit are represented. fig. 13. acceleration of 4 march, 1977 earthquake at the surface, direction ns –strata (cohesive soil) fig. 14. acceleration of 31 august, 1986 earthquake at the surface, direction ns – strata (cohesive soil) minimum average maximum case 3 case 2 case 1 case 2 case 1 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 fig. 10. maximum shear-strain for different earthquake excitations (cohesionless soil) compared to the cohesive soil deposit, the maximum value of acceleration response spectrum for non-cohesive soil corresponds to the second case, having the value of as max = 0.434 g (fig. 11). the values for the second case and third case are 0.278 g and 0.246 g, respectively. it can be also noticed that the values of spectral accelerations are lower compared to the cohesive soil. the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 12 are: as max =0.626 g for 1977 earthquake, as max = 0.408 g, for 1986 and as max =0.411 g for 1990. fig. 11. acceleration response spectrum at the surface (cohesionless soil) fig. 12. acceleration response spectrum at the bedrock (cohesionless soil) in fig. 13, fig. 14 and fig. 15 the acceleration data recorded at the surface with the software strata for a cohesive soil deposit are represented. in fig. 16, fig. 17 and fig. 18 the acceleration data recorded at the surface with the software strata for a cohesionless soil deposit are represented. fig. 13. acceleration of 4 march, 1977 earthquake at the surface, direction ns –strata (cohesive soil) fig. 14. acceleration of 31 august, 1986 earthquake at the surface, direction ns – strata (cohesive soil) minimum average maximum case 3 case 2 case 1 case 2 case 1 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 fig. 11 acceleration response spectrum at the surface (cohesionless soil) fig. 12 acceleration response spectrum at the bedrock (cohesionless soil) 11 12 89 journal of sustainable architecture and civil engineering 2014/4/9 using the acceleration data recorded on romania territory during 1977, 1986 and 1990 earthquake, empirical model proposed by idriss (1990) and strata software we can make predictions on the dynamic behavior for different sites. from the results obtained, using the program strata for a clayey and sandy soil deposit, it was found that seismic propagation of the waves is directly related to the type of the earth, and its physical and mechanical characteristics. also, the type of soil directly influences spectral ratio and acceleration response spectrum. this work presents a preliminary study on evaluation of the shear modulus and damping ratio curves. for future researches we will intend to analyze an equivalent-linear modeling of site response based on cohesive soil deposit such as bahlui clay. conclusions fig. 15. acceleration of 30 may, 1990 earthquake at the surface direction ns – strata (cohesive soil) fig. 16. acceleration of 4 march, 1977 earthquake at the surface, direction ns (cohesionless soil) fig. 17. acceleration of 31 august, 1986 earthquake at the surface, direction ns (cohesionless soil) fig. 18. acceleration of 30 may, 1990 earthquake at the surface direction ns (cohesionless soil) 5. conclusions using the acceleration data recorded on romania territory during 1977, 1986 and 1990 earthquake, empirical model proposed by idriss (1990) and strata software we can make predictions on the dynamic behavior for different sites. from the results obtained, using the program strata for a clayey and sandy soil deposit, it was found that seismic propagation of the waves is directly related to the type of the earth, and its physical and mechanical characteristics. also, the type of soil directly influences spectral ratio and acceleration response spectrum. this work presents a preliminary study on evaluation of the shear modulus and damping ratio curves. for future researches we will intend to analyze an equivalent-linear modeling of site response based on cohesive soil deposit such as bahlui clay. acknowledgment the authors would like to thank to ellen m. rathje and albert kottke, for free use of strata software. references balan s., and others 1983. cutremurul de pământ din românia de la 4 martie 1977 [the romania earthquake of 4 march 1977].editura academiei. bahar r., saci l., louadj s., vicens e. 2012. numerical evaluation of shear modulus degradation and damping curves of algerian soils using geophysical tests. in: 15 th world conference on earthquake engineering. lisbon, portugal. eurocode 8 1998: design of structures for earthquake resistance. part 1: general rules, seismic actions and rules for buildings. graizer v. 2011. treasure island geotechnical array – case study for site response analysis. in: 4 th iaspei/ iaee international symposium: effects of surface geology on seismic motion. california, united states of america. incerc bucure ti, 2004. available at: http://www.incerc2004.ro/accelerograme.htm (accessed 10 march 2014). ishibashi i., zhang x. 1993. unified dynamic shear modulus and damping ratio of sand and clay. in: soils and foundations, japan. 1993, vol. 33, 182-191. jafarian y., haddad a., javdanian h. 2014. predictive model for normalized shear modulus of cohesive soils. in: acta geodynamica et geomaterial, vol. 11, 1(173), 89-100. luke b., liu y. 2008. site response zones and short-period earthquake ground motion projections for las vegas basin. in: journal of earth system science, 2(117), 757-772. http://dx.doi.org/10.1007/s12040-008-0059-1 mahin s., (2008). sustainable design considerations in earthquake engineering. in: the 14 th woeld conference on earthquake engineering, beijing, china. matosovic n., hashash y. 2012. practices and procedures for sitespecific evaluations of earthquake ground motions. available at: http://www.national-academies.org/trb/bookstore. pomonis a., coburn a.w., ledbetter s. (1990). the vrancea romania earthquakes of 30-31 may 1990. a field report by e.e.f.i.t. rathje e. m., kottke a. 2013. strata. available at: https://nees.org/resources/strata. sokolov v., boese m., wenyel f. 2008. shakemap methodology based on fourier amplitude spectra and its application for the case of vrancea earthquakes in romania. in: the 14 th woeld conference on earthquake engineering, beijing, china. fig. 15. acceleration of 30 may, 1990 earthquake at the surface direction ns – strata (cohesive soil) fig. 16. acceleration of 4 march, 1977 earthquake at the surface, direction ns (cohesionless soil) fig. 17. acceleration of 31 august, 1986 earthquake at the surface, direction ns (cohesionless soil) fig. 18. acceleration of 30 may, 1990 earthquake at the surface direction ns (cohesionless soil) 5. conclusions using the acceleration data recorded on romania territory during 1977, 1986 and 1990 earthquake, empirical model proposed by idriss (1990) and strata software we can make predictions on the dynamic behavior for different sites. from the results obtained, using the program strata for a clayey and sandy soil deposit, it was found that seismic propagation of the waves is directly related to the type of the earth, and its physical and mechanical characteristics. also, the type of soil directly influences spectral ratio and acceleration response spectrum. this work presents a preliminary study on evaluation of the shear modulus and damping ratio curves. for future researches we will intend to analyze an equivalent-linear modeling of site response based on cohesive soil deposit such as bahlui clay. acknowledgment the authors would like to thank to ellen m. rathje and albert kottke, for free use of strata software. references balan s., and others 1983. cutremurul de pământ din românia de la 4 martie 1977 [the romania earthquake of 4 march 1977].editura academiei. bahar r., saci l., louadj s., vicens e. 2012. numerical evaluation of shear modulus degradation and damping curves of algerian soils using geophysical tests. in: 15 th world conference on earthquake engineering. lisbon, portugal. eurocode 8 1998: design of structures for earthquake resistance. part 1: general rules, seismic actions and rules for buildings. graizer v. 2011. treasure island geotechnical array – case study for site response analysis. in: 4 th iaspei/ iaee international symposium: effects of surface geology on seismic motion. california, united states of america. incerc bucure ti, 2004. available at: http://www.incerc2004.ro/accelerograme.htm (accessed 10 march 2014). ishibashi i., zhang x. 1993. unified dynamic shear modulus and damping ratio of sand and clay. in: soils and foundations, japan. 1993, vol. 33, 182-191. jafarian y., haddad a., javdanian h. 2014. predictive model for normalized shear modulus of cohesive soils. in: acta geodynamica et geomaterial, vol. 11, 1(173), 89-100. luke b., liu y. 2008. site response zones and short-period earthquake ground motion projections for las vegas basin. in: journal of earth system science, 2(117), 757-772. http://dx.doi.org/10.1007/s12040-008-0059-1 mahin s., (2008). sustainable design considerations in earthquake engineering. in: the 14 th woeld conference on earthquake engineering, beijing, china. matosovic n., hashash y. 2012. practices and procedures for sitespecific evaluations of earthquake ground motions. available at: http://www.national-academies.org/trb/bookstore. pomonis a., coburn a.w., ledbetter s. (1990). the vrancea romania earthquakes of 30-31 may 1990. a field report by e.e.f.i.t. rathje e. m., kottke a. 2013. strata. available at: https://nees.org/resources/strata. sokolov v., boese m., wenyel f. 2008. shakemap methodology based on fourier amplitude spectra and its application for the case of vrancea earthquakes in romania. in: the 14 th woeld conference on earthquake engineering, beijing, china. 17 18 fig. 17 acceleration of 31 august, 1986 earthquake at the surface, direction ns (cohesionless soil) fig. 18 acceleration of 30 may, 1990 earthquake at the surface direction ns (cohesionless soil) fig. 15. acceleration of 30 may, 1990 earthquake at the surface direction ns – strata (cohesive soil) fig. 16. acceleration of 4 march, 1977 earthquake at the surface, direction ns (cohesionless soil) fig. 17. acceleration of 31 august, 1986 earthquake at the surface, direction ns (cohesionless soil) fig. 18. acceleration of 30 may, 1990 earthquake at the surface direction ns (cohesionless soil) 5. conclusions using the acceleration data recorded on romania territory during 1977, 1986 and 1990 earthquake, empirical model proposed by idriss (1990) and strata software we can make predictions on the dynamic behavior for different sites. from the results obtained, using the program strata for a clayey and sandy soil deposit, it was found that seismic propagation of the waves is directly related to the type of the earth, and its physical and mechanical characteristics. also, the type of soil directly influences spectral ratio and acceleration response spectrum. this work presents a preliminary study on evaluation of the shear modulus and damping ratio curves. for future researches we will intend to analyze an equivalent-linear modeling of site response based on cohesive soil deposit such as bahlui clay. acknowledgment the authors would like to thank to ellen m. rathje and albert kottke, for free use of strata software. references balan s., and others 1983. cutremurul de pământ din românia de la 4 martie 1977 [the romania earthquake of 4 march 1977].editura academiei. bahar r., saci l., louadj s., vicens e. 2012. numerical evaluation of shear modulus degradation and damping curves of algerian soils using geophysical tests. in: 15 th world conference on earthquake engineering. lisbon, portugal. eurocode 8 1998: design of structures for earthquake resistance. part 1: general rules, seismic actions and rules for buildings. graizer v. 2011. treasure island geotechnical array – case study for site response analysis. in: 4 th iaspei/ iaee international symposium: effects of surface geology on seismic motion. california, united states of america. incerc bucure ti, 2004. available at: http://www.incerc2004.ro/accelerograme.htm (accessed 10 march 2014). ishibashi i., zhang x. 1993. unified dynamic shear modulus and damping ratio of sand and clay. in: soils and foundations, japan. 1993, vol. 33, 182-191. jafarian y., haddad a., javdanian h. 2014. predictive model for normalized shear modulus of cohesive soils. in: acta geodynamica et geomaterial, vol. 11, 1(173), 89-100. luke b., liu y. 2008. site response zones and short-period earthquake ground motion projections for las vegas basin. in: journal of earth system science, 2(117), 757-772. http://dx.doi.org/10.1007/s12040-008-0059-1 mahin s., (2008). sustainable design considerations in earthquake engineering. in: the 14 th woeld conference on earthquake engineering, beijing, china. matosovic n., hashash y. 2012. practices and procedures for sitespecific evaluations of earthquake ground motions. available at: http://www.national-academies.org/trb/bookstore. pomonis a., coburn a.w., ledbetter s. (1990). the vrancea romania earthquakes of 30-31 may 1990. a field report by e.e.f.i.t. rathje e. m., kottke a. 2013. strata. available at: https://nees.org/resources/strata. sokolov v., boese m., wenyel f. 2008. shakemap methodology based on fourier amplitude spectra and its application for the case of vrancea earthquakes in romania. in: the 14 th woeld conference on earthquake engineering, beijing, china. fig. 15. acceleration of 30 may, 1990 earthquake at the surface direction ns – strata (cohesive soil) fig. 16. acceleration of 4 march, 1977 earthquake at the surface, direction ns (cohesionless soil) fig. 17. acceleration of 31 august, 1986 earthquake at the surface, direction ns (cohesionless soil) fig. 18. acceleration of 30 may, 1990 earthquake at the surface direction ns (cohesionless soil) 5. conclusions using the acceleration data recorded on romania territory during 1977, 1986 and 1990 earthquake, empirical model proposed by idriss (1990) and strata software we can make predictions on the dynamic behavior for different sites. from the results obtained, using the program strata for a clayey and sandy soil deposit, it was found that seismic propagation of the waves is directly related to the type of the earth, and its physical and mechanical characteristics. also, the type of soil directly influences spectral ratio and acceleration response spectrum. this work presents a preliminary study on evaluation of the shear modulus and damping ratio curves. for future researches we will intend to analyze an equivalent-linear modeling of site response based on cohesive soil deposit such as bahlui clay. acknowledgment the authors would like to thank to ellen m. rathje and albert kottke, for free use of strata software. references balan s., and others 1983. cutremurul de pământ din românia de la 4 martie 1977 [the romania earthquake of 4 march 1977].editura academiei. bahar r., saci l., louadj s., vicens e. 2012. numerical evaluation of shear modulus degradation and damping curves of algerian soils using geophysical tests. in: 15 th world conference on earthquake engineering. lisbon, portugal. eurocode 8 1998: design of structures for earthquake resistance. part 1: general rules, seismic actions and rules for buildings. graizer v. 2011. treasure island geotechnical array – case study for site response analysis. in: 4 th iaspei/ iaee international symposium: effects of surface geology on seismic motion. california, united states of america. incerc bucure ti, 2004. available at: http://www.incerc2004.ro/accelerograme.htm (accessed 10 march 2014). ishibashi i., zhang x. 1993. unified dynamic shear modulus and damping ratio of sand and clay. in: soils and foundations, japan. 1993, vol. 33, 182-191. jafarian y., haddad a., javdanian h. 2014. predictive model for normalized shear modulus of cohesive soils. in: acta geodynamica et geomaterial, vol. 11, 1(173), 89-100. luke b., liu y. 2008. site response zones and short-period earthquake ground motion projections for las vegas basin. in: journal of earth system science, 2(117), 757-772. http://dx.doi.org/10.1007/s12040-008-0059-1 mahin s., (2008). sustainable design considerations in earthquake engineering. in: the 14 th woeld conference on earthquake engineering, beijing, china. matosovic n., hashash y. 2012. practices and procedures for sitespecific evaluations of earthquake ground motions. available at: http://www.national-academies.org/trb/bookstore. pomonis a., coburn a.w., ledbetter s. (1990). the vrancea romania earthquakes of 30-31 may 1990. a field report by e.e.f.i.t. rathje e. m., kottke a. 2013. strata. available at: https://nees.org/resources/strata. sokolov v., boese m., wenyel f. 2008. shakemap methodology based on fourier amplitude spectra and its application for the case of vrancea earthquakes in romania. in: the 14 th woeld conference on earthquake engineering, beijing, china. 15 16 fig. 15 acceleration of 30 may, 1990 earthquake at the surface direction ns – strata (cohesive soil) fig. 16 acceleration of 4 march, 1977 earthquake at the surface, direction ns (cohesionless soil) fig. 10. maximum shear-strain for different earthquake excitations (cohesionless soil) compared to the cohesive soil deposit, the maximum value of acceleration response spectrum for non-cohesive soil corresponds to the second case, having the value of as max = 0.434 g (fig. 11). the values for the second case and third case are 0.278 g and 0.246 g, respectively. it can be also noticed that the values of spectral accelerations are lower compared to the cohesive soil. the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 12 are: as max =0.626 g for 1977 earthquake, as max = 0.408 g, for 1986 and as max =0.411 g for 1990. fig. 11. acceleration response spectrum at the surface (cohesionless soil) fig. 12. acceleration response spectrum at the bedrock (cohesionless soil) in fig. 13, fig. 14 and fig. 15 the acceleration data recorded at the surface with the software strata for a cohesive soil deposit are represented. in fig. 16, fig. 17 and fig. 18 the acceleration data recorded at the surface with the software strata for a cohesionless soil deposit are represented. fig. 13. acceleration of 4 march, 1977 earthquake at the surface, direction ns –strata (cohesive soil) fig. 14. acceleration of 31 august, 1986 earthquake at the surface, direction ns – strata (cohesive soil) minimum average maximum case 3 case 2 case 1 case 2 case 1 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 fig. 10. maximum shear-strain for different earthquake excitations (cohesionless soil) compared to the cohesive soil deposit, the maximum value of acceleration response spectrum for non-cohesive soil corresponds to the second case, having the value of as max = 0.434 g (fig. 11). the values for the second case and third case are 0.278 g and 0.246 g, respectively. it can be also noticed that the values of spectral accelerations are lower compared to the cohesive soil. the maximum values of acceleration response spectrum at the bedrock highlighted in fig. 12 are: as max =0.626 g for 1977 earthquake, as max = 0.408 g, for 1986 and as max =0.411 g for 1990. fig. 11. acceleration response spectrum at the surface (cohesionless soil) fig. 12. acceleration response spectrum at the bedrock (cohesionless soil) in fig. 13, fig. 14 and fig. 15 the acceleration data recorded at the surface with the software strata for a cohesive soil deposit are represented. in fig. 16, fig. 17 and fig. 18 the acceleration data recorded at the surface with the software strata for a cohesionless soil deposit are represented. fig. 13. acceleration of 4 march, 1977 earthquake at the surface, direction ns –strata (cohesive soil) fig. 14. acceleration of 31 august, 1986 earthquake at the surface, direction ns – strata (cohesive soil) minimum average maximum case 3 case 2 case 1 case 2 case 1 case 3 minimum average maximum minimum average maximum case 3 case 2 case 1 1413 fig. 14 acceleration of 31 august, 1986 earthquake at the surface, direction ns – strata (cohesive soil) fig. 13 acceleration of 4 march, 1977 earthquake at the surface, direction ns – strata (cohesive soil) in fig. 16, fig. 17 and fig. 18 the acceleration data recorded at the surface with the software strata for a cohesionless soil deposit are represented. journal of sustainable architecture and civil engineering 2014/4/9 90 balan s., and others 1983. cutremurul de pământ din românia de la 4 martie 1977 [the romania earthquake of 4 march 1977].editura academiei. bahar r., saci l., louadj s., vicens e. 2012. numerical evaluation of shear modulus degradation and damping curves of algerian soils using geophysical tests. in: 15th world conference on earthquake engineering. lisbon, portugal. eurocode 8 1998: design of structures for earthquake resistance. part 1: general rules, seismic actions and rules for buildings. graizer v. 2011. treasure island geotechnical array – case study for site response analysis. in: 4th iaspei/ iaee international symposium: effects of surface geology on seismic motion. california, united states of america. incerc bucurești, 2004. available at: http://www. incerc2004.ro/accelerograme.htm (accessed 10 march 2014). ishibashi i., zhang x. 1993. unified dynamic shear modulus and damping ratio of sand and clay. in: soils and foundations, japan. 1993, vol. 33, 182191. jafarian y., haddad a., javdanian h. 2014. predictive model for normalized shear modulus of cohesive soils. in: acta geodynamica et geomaterial, vol. 11, 1(173), 89-100. luke b., liu y. 2008. site response zones and shortperiod earthquake ground motion projections for las vegas basin. in: journal of earth system science, 2(117), 757-772. http://dx.doi.org/10.1007/ s12040-008-0059-1 ana nicuţă head of department gheorghe asachi” technical university transportation infrastructure and foundations department main research area geotechnical engineering, foundations under special conditions, soil dynamics address 43 d. mangeron, 700050 iasi, romania tel. +40740823522 e-mail: nicutaana@yahoo.com alexandra alisa găină phd student gheorghe asachi” technical university transportation infrastructure and foundations department main research area geotechnical engineering and soil dynamics address 43 d. mangeron, 700050 iasi, romania tel. +40747877217 e-mail: alisa.gaina@yahoo.com the authors would like to thank to ellen m. rathje and albert kottke, for free use of strata software. acknowledgment mahin s., (2008). sustainable design considerations in earthquake engineering. in: the 14thwoeld conference on earthquake engineering, beijing, china. matosovic n., hashash y. 2012. practices and procedures for site-specific evaluations of earthquake ground motions. available at: http:// www.national-academies.org/trb/bookstore. pomonis a., coburn a.w., ledbetter s. (1990). the vrancea romania earthquakes of 30-31 may 1990. a field report by e.e.f.i.t. rathje e. m., kottke a. 2013. strata. available at: https://nees.org/resources/strata. sokolov v., boese m., wenyel f. 2008. shakemap methodology based on fourier amplitude spectra and its application for the case of vrancea earthquakes in romania. in: the 14thwoeld conference on earthquake engineering, beijing, china. vlad i., vlad m., 2008. behavior of dwellings during strong earthquakes in romania. in: the 14thworld conference on earthquake engineering, beijing, china. kottke a., rathje e. 2013. technical manual for strata. peer report, universitz of california, berkeley. zhang j., andrus r. d., juang c.h. 2005. normalized shear modulus and material damping ratio relationship. in: journal of geotechnical and geoenvironmental engineering 4(453), 453464. http://dx.doi.org/10.1061/(asce)10900241(2005)131:4(453) references about the authors 39 journal of sustainable architecture and civil engineering 2022/2/31 *corresponding author: 90136@uotechnology.edu.iq investigating the impact of educational space design in fostering social distancing: a case study of the university of technology buildings, iraq received 2022/02/21 accepted after revision 2022/06/01 journal of sustainable architecture and civil engineering vol. 2 / no. 31 / 2022 pp. 39-57 doi 10.5755/j01.sace.31.2.30746 investigating the impact of educational space design in fostering social distancing: a case study of the university of technology buildings, iraq jsace 2/31 http://dx.doi.org/10.5755/j01.sace.31.2.30746 ahmed m. hameed al-delfi*, abdullah s. salman university of technology iraq, department of architecture, baghdad, iraq introduction abstract in the light of the ongoing outbreak of epidemics, the iraqi government ordered the temporary closure of university buildings and explicit compliance with social distancing, fearing increased infection rates among the large numbers of students. this closure, and the fear of infection, acted as an obstacle for users of educational spaces. to overcome this challenge, the study aimed to investigate the impact of educational space design on the effectiveness of social distancing to reduce the spread of epidemics. the shape, area, and furniture arrangement pattern were determined in the study of educational spaces design as a spatial configuration through the level of wayfinding and permeability. to better understand the relationship between the design of the current educational spaces and the effectiveness of social distancing, this study used a visual survey, field visits, and a quantitative method using a space syntax analysis. and the analysis was carried out on various models of educational spaces design in three elected samples of the buildings of the technological university baghdad, iraq. the analysis values were represented in quantitative tables to illustrate the values of the space syntax attributes and charts showing measures of permeability and wayfinding in all the analysed models. the study results show an impact and a close relationship between the elements of educational space design as a spatial composition and the effectiveness of social distancing. this relationship is formed by the effect of the shape, space, and furniture arrangement pattern in changing the values of spatial space relationships. furthermore, permeability and wayfinding as spatial characteristics depend on those relationships and control users’ circulation within the educational space, which is essential in determining the effectiveness of social distancing. keywords: educational space design, university buildings, social distancing, space syntax. after the outbreak of (covid-19) worldwide, iraq witnessed many waves of epidemics during this period. in response, the iraqi government took strict measures, including implementing forced social distancing, following who’s recommendations as preventive measures to reduce the spread of epidemics (who, 2020). social distancing is the most effective strategy for reducing the spread of epidemics, especially in cramped spaces within buildings where many people are present (prem et al., 2020). the iraqi government has repeatedly ordered the temporary closure of university buildings and explicit compliance with social distancing, fearing increased infection rates among the large numbers of students. this closure, and the fear of infection, acted as an obstacle for most university building users in educational activities (ayyildiz and taskin gumus, 2021). journal of sustainable architecture and civil engineering 2022/2/31 40 literature review furthermore, to overcome this challenge, many questions have arisen about the problems of designing existing university buildings and how to improve their ability to adapt to new and emerging needs with pandemic outbreaks (güzelci et al., 2020; ian taylor, 2021, p. 188). accordingly, and with the importance of ensuring continuity of use and at the same time preventing epidemics, the design of architectural spaces must be studied and evaluated from the perspective of epidemic prevention (megahed and ghoneim, 2020; salama, 2020); these include educational spaces in university buildings. the fact that educational space is one of the essential factors in supporting the success of the educational environment that embraces students and faculty (menon and suresh, 2020). however, the educational process as an activity practiced in the spaces of university buildings is an essential part of this process based on participation and social interaction between students and faculty, especially in co-working spaces, laboratories, and classrooms (alnusairat et al., 2020). that is, part of the educational activity is the social aspect. thus, educational spaces can increase the spread of potential infections among users. after this saying, the educational spaces must architecturally have spatial characteristics that facilitate compliance with social distancing among users. these spatial solutions are critical because of the approach of conducting educational activities in university buildings, which means more potential risks in increasing the spread of epidemics. university of technology buildings have a range of facilities, some educational establishments, and others administrative and service buildings. three samples of educational buildings were elected to study the design of educational spaces in terms of shape, area, and furniture arrangement pattern. achieving continuity in the use of spaces with effective implementation of social distancing is one aspect of improving the ability of educational buildings to adapt to emerging requirements during pandemic outbreaks (güzelci et al., 2020). the study aimed to investigate the impact of educational space design on the effectiveness of social distancing to reduce the spread of epidemics. achieving the aim of this study requires careful evaluation of the spatial configuration of the current educational space and a better understanding of users’ internal circulation toward creating an enhanced spatial design that fosters compliance with social distancing within the educational space. more specifically, this study seeks to answer the following research questions: 1. how do elements of educational space design impact the effectiveness of social distancing? 2. what is the appropriate design for an educational space with an excellent social distancing effectiveness level? the study used the space syntax analysis through the level of permeability and wayfinding, as they are influential factors in facilitating the implementation of social distancing (abdul nasir et al., 2021). the space syntax is a method to describe, analyse and measure spatial relationships of spatial configuration within or outside architectural spaces (jiang and claramunt, 2002). this analysis provides clear explanations about the potential impact of educational space design as a spatial composition on the level of social distancing effectiveness. previous studies that dealt with the architectural design of public buildings from the viewpoint of epidemic prevention emphasized the critical role of the building’s layout and architectural spaces in achieving a safe and healthy internal environment that protects humans from the risks of the spread of epidemics (andrei fezi, 2021, p. 2; fezi, 2020; salman and hameed, 2021a). in addition, health and epidemic-free educational spaces positively affect students’ health and productivity and achieve quality and continuity of use of these spaces (deshmukh, 2021). however, one of the lessons learned from the outbreak of the (covid-19) pandemic and subsequent epidemics was the detection of some design problems and challenges, as well as the limited capacity of existing buildings such as homes, commercial buildings, university buildings, and other buildings to face the risk of epidemics (megahed and ghoneim, 2020). the effects of this are some of the alerts that motivated architecture professionals to rethink the interior and exterior design of buildings and to develop health standards and approaches that are more effective in preventing current and future epidemics. 41 journal of sustainable architecture and civil engineering 2022/2/31 educational space design studies dealing with the evaluative issues of indoor spaces towards increasing the effectiveness of social distancing; among these studies is a study conducted by abdul nasir et al. (2021). to evaluate the layout of a multi-story recreational building and study spatial organization and management factors that affect the effectiveness of social distancing by focusing on the level of permeability and finding the way as indicators of the building’s spatial configuration. the study methodology used the method of space syntax analysis by determining the depth, connectivity, and integration (abdul nasir et al., 2021). either about the relationship between the implementation of social distancing and the layout pattern of common and public indoor spaces in residential buildings, a study conducted by kareem and baper (2021). to examine the strength and direction of relationships between common indoor spaces and epidemic control indicators and determine the practical pattern of indoor space planning. the study also adopted an integration, connectivity, and visibility analysis using the space syntax method (kareem and baper, 2021). also, about the existing educational buildings and how to improve their ability to adapt to the emerging needs of the (covid-19) pandemic, the study of güzelci et al. (2020) provides a new algorithm for post-occupancy assessment of existing school buildings and provides solutions to improve the adaptability of these buildings. the study used two-dimensional plans of indoor spaces as input to the analysis process using (rhino/grasshopper and the add-on galapagos) (güzelci et al., 2020). also, concerning strengthening the design of the indoor environment to meet the current challenge of reconfiguring standard physical settings with social distancing measures, a study conducted by ugail et al. (2021). to produce appropriate design solutions, the user can choose the most feasible option on the move, addressing the limitations and requirements of specific physical spaces such as space dimensions, door position, windows, corridors, and variables related to the indoor airflow pattern (ugail et al., 2021). finally, among studies on the relationship between space resilience and reducing the spread of the epidemic is a study conducted by salman and hameed (2021b). this study showed the types and approaches of flexibility in space regulation. it determined the fundamental dimension of architectural composition regarding the degree of connection or isolation to reduce the spread of epidemics. this study theoretically sought to develop internal space assessment and design criteria to increase the building’s effectiveness in resisting epidemics from an architectural perspective (salman and hameed, 2021b). despite the above studies, a range of building design elements adopts diverse analysis approaches toward reducing the spread of epidemics on the one hand and increasing the effectiveness of social distancing on the other. however, no study examined the impact of educational space design (in terms of space shape, area, and furniture arrangement pattern) on the effectiveness of social distancing. therefore, an accurate evaluation should conduct using space syntax analysis to investigate the impact of the educational space design for university buildings on the effectiveness of social distancing. space, in general, can be interpreted from the physical side as a three-dimensional field consisting of a set of physical elements that have specific characteristics connected according to relationships to meet users’ basic needs and requirements. the design of that space is the set of processes for planning and designing spaces within buildings (ching and binggeli, 2018, pp. 2–34). either for the educational space, it is part of the academic environment. it is the product of design processes that depend on a relationship between space forms and learning practices according to specific objectives to achieve users’ educational activities (gislason, 2010). space’s connection to the educational process is at several functional levels, including; a space for lectures, laboratories, seminars, conferences, and research (research laboratories and faculty offices). in addition, the educational space includes a range of social relationships. consequently, it has several determinants of its composition in terms of signature, area, and space suited to the type of educational activities carried out (ilvitskaya et al., 2019). therefore, this study’s scope will determine the shape, area, and furniture arrangement pattern as physical journal of sustainable architecture and civil engineering 2022/2/31 42 variables in the educational space design. physically, space design is an essential platform for forming and managing occupants’ circulation within space (omer and goldblatt, 2017). also, the movement of occupants in architectural spaces is a crucial factor reflected in the effectiveness of social distancing (usman et al., 2020). the outbreak of the epidemics in this era refers to many risks that inevitably affect the future of humanity and a new normal lifestyle that deals with the design aspects that, in turn, affect people’s health (megahed and ghoneim, 2020). infection is transmitted either directly through droplets or indirectly after touching the contaminated surfaces (jang et al., 2020). especially within narrow spaces, which raises alerts about new space designing guidelines. the practice of social distancing and spatial isolation has proven to be relatively effective in controlling infection in health care facilities (lewnard and lo, 2020). social or physical distancing is a kinetic-spatial mechanism that maintains a distance between persons in public places of at least 2m (6 feet). it prevents people from gathering and staying in crowds and reduces direct contact with people in internal and external spaces (cdc, 2021). the primary purpose of social distancing is to prevent the spread of infectious diseases and viruses, which are transmitted quickly to humans through physical contact between people (wilder-smith and freedman, 2020). the social distancing and reducing the spread of (covid-19) permeability space spatial characteristics educational spaces in university buildings are usually designed with different shapes, areas, and patterns to arrange furniture depending on the type of educational function, the design objective of that space, and the changing needs that arise due to unavoidable circumstances. for example, implementing the safe distance of social distancing and fulfilling functional requirements have become an urgent need after the outbreak of epidemics (güzelci et al., 2020). on the other side, many spatial studies confirm that the occupants’ movement, in general, is directly affected by spatial relationships within the space system, where this relativity depends on spatial composition characteristics that create a network of visual and motor relationships that contribute to the understanding and assimilation of the place (haq, 2003; zerouati and bellal, 2020). accordingly, and what it takes to understand the impact of user circulation on the social distancing effectiveness, the designer must predict the movement paths the users will follow. in addition to identifying the reasons for users’ gathering in some zones from the educational space. the spatial characteristics of space that the study will address are: the level of space permeability in architecture indicates the implicit spatial quality of spaces from the point of entry to the farthest point in space (mclane, 2013, p. 6). furthermore, the space permeability level allows a description of spatial efficiency and analysis of the hierarchy of indoor spaces in the building (mustafa and hassan, 2013). accordingly, the level of permeability provides an understanding of the spatial arrangement priorities in terms of the educational uses position, the hierarchy between public and private, and the depth of distance between parts of the space. thus, the increasing depth of a specific point within space away from the entry point indicates a decrease in the level of permeability and vice versa (mclane, 2015). in the context of educational spaces that meet multiple educational uses. zoning and prioritizing places of practice for these educational uses based on permeability can be crucial in increasing the effectiveness of social distancing among occupants (abdul nasir et al., 2021). educational spaces must be designed based on determining the most connected areas between occupants and making them at the lowest depth near the entry point and vice versa to adapt these spaces to social distancing. in spatial studies, permeability is associated with accessibility and visibility. it indicates the connectivity between spatial points, allowing easy and direct access to the other space points. the contiguity relationship between points describes direct permeability, while the convergence relationship describes the indirect permeability of space (beck and turkienicz, 2009). visibility refers to 43 journal of sustainable architecture and civil engineering 2022/2/31 visual connectivity between spatial space points, as noted by hanson (1999), permeability (where you can go), and visibility (what you can see). and they are closely related through spatial layers, transparency, intersectional penetration of volume, and the disintegration of boundaries (hanson, 1999, p. 54). the space syntax tool the research will adopt to study permeability is the visibility map, usually used to study visibility variables (turner et al., 2001). the term “wayfinding” dates back to the middle of the last century when kevin lynch first mentioned it in his book the image of the city. to understand people’s cognitive and analytical abilities toward the built environment and classify elements that prevent people from getting lost in urban spaces through experimental processes (lynch, 1962, p. 5). the wayfinding around explaining the relationship between space and human behavior is trying to clarify decision-making processes on finding the appropriate way from root to destination when they waste people in space (maghool et al., 2018). concerning space design and guidance strategies that contribute to raising the level of wayfinding within buildings, many spatial studies have referred to the possibility of using architectural space and indoor processing as a visual guide for people to determine their direction. for example, in architectural spaces such as halls, corridors, stairs, and elevators, an asymmetrical layout pattern is used for indoor spaces, uncomplicated linear paths, and other spatial characteristics that facilitate direction determination and path selection. either indoor processor includes space shape, structure and boundaries, wall color, changes in floor design, furniture type, use of lighting to maximize focus on a given space, ceiling processors, utilization of function points, markings, and other tools and equipment (arendholz and becker, 2015; chen et al., 2021; peponis et al., 1990). these design treatments reduce people’s chances of getting lost and spatial anxiety, and getting lost results in lower spatial efficiency and greater reliance on help from other people to locate (lawton, 1996). thus, people who are unsure where they are and how to get to their destination will intersect with other people within space (devlin, 2014). these indiscriminate intersections, which can increase physical connectivity and user convergences, are not commensurate with the implementation of social distancing within spaces. the wayfinding is impacted by the implicit intelligibility of space as spatial configuration through reconnaissance movement and spatial cognition. the reconnaissance movement is directly between the point of origin and the intended destination in spaces with excellent clarity. however, the mysterious spaces tend to be more complex and indirect (yun and kim, 2007). in space syntax methodology, intelligibility is measured by correlating the connectivity with global integration (hillier, 1996, p. 245). therefore, the wayfinding depends on intelligibility and accessibility within space, which can be measured by obtaining connectivity and global integration; since the origin of the reconnaissance movement lies in reaching the destination, the more synthetic steps, the more words and the path can be more complex during the movement (beck and turkienicz, 2009). as a result, users’ mobility within the educational space is complicated, affecting their compliance with social distancing. the space syntax tool the research will adopt to study wayfinding is the axial map, usually used to study people’s internal circulation (omer and goldblatt, 2017). wayfinding case study the elected study case is the buildings of the university of technology in baghdad, first rusafa. it can be accessed through muhammad al-qasim street, surrounded by it on the east side, opposite al-shaab stadium, and from the other side al-sina’a street. the university has a range of buildings, some scientific engineering departments, and other administrative and service buildings, established in 1975 as one of iraq’s ministry of higher education and scientific research universities. the study selected three samples of the university of technology buildings, namely the architectural engineering department, the civil engineering department, and the control and systems engineering department. they are public buildings that provide an essential service to journal of sustainable architecture and civil engineering 2022/2/31 44 the community: university education, which has been significantly affected by the conditions of epidemic outbreaks. the research was limited to studying the design of internal educational spaces for these buildings. these spaces are used for educational functions at multiple levels and stages, such as faculty offices, classrooms for theoretical lectures, laboratories, libraries, and co-working spaces. and are used by large numbers of employees and various categories such as students, faculty, and staff. the last is one of the justifications for electing that is directly influencing the issue of social distancing (a large number of users and the time they stay in educational spaces). these buildings are also architecturally different in the design of educational spaces from the spectrum of shape, area, and furniture arrangement pattern, as shown in table 1. table 1 the most crucial information of the case study (author) first sample building of architectural engineering department description: it’s one of the scientific departments of the university of technology. it was built in the seventies of the last century and used by more than (500) persons, faculty, staff, and students to study architectural engineering. the building consists of four floors; the ground floor includes classrooms for theoretical lessons and architectural design workshops, as shown in fig. 1. building plan: fig. 1. the ground floor plan of the architecture eng. dep. building (authors), based on the projects dep. design of educational spaces: shape area furniture arrangement pattern _ rectangular. _ (85 127) m2. _ grid. _ linear. _ external-central. second sample building of civil engineering department description: it’s one of the oldest scientific departments at the university of technology. it was built in the nineties of the last century. it was used as a department to study civil engineering, comprising three disciplines in civil engineering for more than (850) persons, faculty, staff, and students. the building consists of three floors, with a range of educational spaces, including classrooms and laboratories, as in fig. 2. 45 journal of sustainable architecture and civil engineering 2022/2/31 first sample building of architectural engineering department building plan: fig. 2. the ground floor plan of the civil eng. dep. building (authors), based on the projects dep. design of educational spaces: shape area furniture arrangement pattern _ octagonal. _ rectangle triangle corner. _ (75 250) m2. _ grid. _ linear. _ inner-central. third sample building of control and systems engineering department description: the building was built in 2008, considered one of the university’s modern buildings. it was used as a department to study the control and systems engineering for more than (400) persons, faculty, staff, and students. the building consists of four floors, with educational spaces on the ground floor, such as laboratories, and one as a multi-purpose classroom, as shown in fig. 3. building plan: fig. 3. the ground floor plan of the control and systems eng. dep. building (authors), based on the projects dep. design of educational spaces: shape area furniture arrangement pattern _ square. _ part of a circle. _ (88 275) m2. _ grid. _ linear. _ central. journal of sustainable architecture and civil engineering 2022/2/31 46 the research methodology used in this study is a visual survey, field visits, and quantitative analysis using a space syntax method to investigate the impact of educational spaces design on the effectiveness of social distancing. the research examined the shape, area, and furniture arrangement pattern as design variables for space. at the same time, permeability and wayfinding are the spatial characteristics variables of educational spaces design. fig. 4 shows the structure of the research methodology used in the study, which began first, reviewing previous studies dealing with keywords on the architectural design of spaces from a social distancing and epidemic prevention perspective to extract the research problem. the research methodology classification and coding fig. 4 a diagram of research methodology (authors) previous studies, which included keywords on spatial formation factors affecting social distancing and the method of analysing the construction of the space sentence, were then reviewed to determine the essential characteristics of educational space as spatial configuration. secondly, determine the case study and elect three samples according to several election justifications that ensure that the profound results of the study are applicable in most educational spaces of iraqi universities. the study then nailed the collection of data and information through field visits to the buildings and a visual survey of the plans for educational spaces design. the design of educational spaces has been classified and coded into various models in shape, space, and furniture arrangement patterns to provide the data required in space syntax analysis. it is an objective analysis tool that works to find the best results that can describe the relativity between research variables. the visibility graph analysis and axial map analysis using (depthmapx) were adopted to examine visual integration, connectivity, choice, and intelligibility as key indicators in the space syntax methodology for evaluating spatial composition characteristics, namely the permeability and wayfinding. accordingly, the space syntax analysis of all educational spaces design models in each sample was performed separately. then the values were represented by tables and charts to facilitate an accurate interpretation of the results. third, the results were discussed to explain the impact of educational space design on the effectiveness of social distancing among users. finally, the study methodology concludes by extracting the conclusions that illustrate the relational characteristic of educational space design as a spatial composition, with specific spatial characteristics that form users’ circulation, which controls the level of social distancing effectiveness within the educational space. the study results can provide a theoretical understanding of designing, evaluating, and using educational spaces in university buildings in compliance with social distancing. for analysis and comparison, the design of educational spaces for elected samples of the study case was classified and coded into a set of different models in terms of shape (x.1), space (x.2), and furniture arrangement pattern (x.3) (güzelci et al., 2020; hassan and megahed, 2021; ugail et al., 2021), as shown in table 2. 47 journal of sustainable architecture and civil engineering 2022/2/31 analyses tool and search indicators table 2 classification and coding of the modules (authors) elements classification and coding shape x.1 rectangular (x.1.1) square (x.1.2) octagonal (x.1.3) triangle corner (x.1.4) part of a circle (x.1.5) area x.2 large (x.2.1) medium (x.2.2) small (x.2.3) (275 200) m2. (199 100) m2. (99 25) m2. furniture arrangement pattern x.3 linear (x.3.1) grid (x.3.2) mixed (x.3.3) external-central (x.3.4) inner-central (x.3.5) source (s): authors. this study attempts to answer research questions about the impact of educational space design elements on the effectiveness of social distancing. research requires a quantitative analysis tool that works to find the best results that can describe the relationship between educational space design and the social distancing effectiveness. the study used the space syntax methodology since those most recent spatial studies dealing with the research context above confirmed the role of the space syntax methodology and its ability to explain human behaviors and social activities, including the potential movement of occupants from the perspective of the spatial configuration of architectural and urban spaces (kishimoto and taguchi, 2014; omer and goldblatt, 2017; shahbazi et al., 2018). in addition, recent architectural studies conducted after the outbreak of the (covid-19) epidemic demonstrated the possibility of journal of sustainable architecture and civil engineering 2022/2/31 48 using the space syntax methodology in studies dealing with the layout of public buildings from the perspective of reducing the spread of epidemics (abdul nasir et al., 2021; kareem and baper, 2021). space syntax space syntax originated and developed in the 1970s at the bartlett unit for architectural studies, university college, london. it is a method for quantifying, analysing, and measuring the spatial relationships in buildings and urban structures (jiang and claramunt, 2002). it is also an objective method for evaluating and investigating spatial relationships between the morphological structure of architectural spaces and social events (shahbazi et al., 2018). technically, the space syntax is defined as a set of techniques to represent and analyse planning and spatial configuration of all types. it means examining the spatial relationship between each unit within the space system, just like examining a word within the text and its relationship to other words (hillier, 1999; hillier et al., 1987). description and measurement of the spatial configuration of spaces using the method of space syntax, based on more than one method of analysis. the analysis will be conducted using the following two methods: _ visibility graph analysis (aga): the initial idea of this analysis came from areas of visibility that were visible from a particular point. in other words, the basis for this type of analysis is the reflection of light that determines the patterns of people’s motor behavior in space (jiang and claramunt, 2002; montello, 2007). by the vga, visual integration and connectivity values can be obtained as explanatory indicators of space permeability level (mclane, 2015). _ axial map analysis (ama): axial lines (axial map) are a graphical diagram that derives from the catalysis of streets and open spaces. this diagram is developed on special software, and it is the basis of the space syntax. the axial map is straight lines of vision and access (shahbazi et al., 2018). and it consists of the lowest and longest straight lines covering all parts of space, and this method reflects the space system’s comprehensive motor pathways (omer and goldblatt, 2017). also, by the ama, choice and intelligibility values can be obtained as explanatory indicators of space wayfinding level (turner et al., 2001). the study depends on the use of depthmapx, which alasdair turner created at university college london, an application based on computer-assisted mathematical algorithms. the program was first designed in 1998 as a simple processor program (turner, 2004). and it is possible to analyse the spatial relationships of architectural and urban spaces quantitatively. the program analyses many measurements that are divided into two parts: _ global measurements: reflect the relationship between any point in the space system with all system parts. _ local measurements: the relationship between any point in the system, and the points directly associated with it, depends only. appropriate indicators for analysis of spatial relationships of educational space, which can be invested in this research, have been determined as follows: _ space syntax indicators in the vga method: the attributes of the space syntax were examined through the vga method using the following indicators; first, visual integration is a global metric. it represents the number of visual steps to be taken from any point within space to see the points in the complex (turner, 2004, p. 1). accordingly, the more excellent the integration value, the closer connecting a point to other points within the space’s spatial configuration (shahbazi et al., 2018). integration indicates the visibility and accessibility of a point within space according to the connection of accessibility and visibility to space permeability (beck and turkienicz, 2009); this means that the higher the integration value, the more strongly connected and integrated the spatial configuration is, which means the higher the accessibility and visibility. thus, the level of space permeability is excellent. secondly, connectivity is a local measure representing the number of points within space that can be 49 journal of sustainable architecture and civil engineering 2022/2/31 fig. 5 a diagram to illustrate the relationship between research indicators (authors) directly seen from a point in the space complex (turner, 2004, p. 16). a high connectivity value indicates more visual connections between points within the architectural space, which means a more direct correlation between the space parts, that is, more pathways of movement and vision and, therefore, an excellent indicator of space permeability. _ space syntax indicators in the ama method: the attributes of the space syntax were examined through the ama method using the following indicators; first, the choice is a general measure of the flow rate of occupants’ movement in space. space offers a high probability of choices from many of the shortest connectivity paths that intersect with that space (shahbazi et al., 2018). if the choice value of the space complex is high, this means easy and smooth movement within space, and thus an excellent indicator of the level of wayfinding within space. secondly, intelligibility is the correlation factor between connectivity and global integration. and it relates to the arrangement of the relationship of parts to each. hillier (1996) defines it as a “relationship analysis between how the complex can be seen in its parts and its general pattern” as a distribution of integration (hillier, 1996, p. 171). and the scattered figure can represent intelligibility analysis. suppose the scattered points form a straight line that rises at 45 degrees from the bottom left to the top right. in that case, this refers to a strong relationship between local connectivity and global integration. thus, the system will be apparent (hillier, 1996, p. 94). by linking clarity to the wayfinding (yun and kim, 2007), a high intelligibility value can be an excellent indicator of the wayfinding level in space. as previously addressed, the relationship between research indicators becomes as shown in fig. 5. _ spatial characteristics scales: the research adopted the attributes of space syntax, visual integration, connectivity, choice, and intelligibility as indicators to evaluate the spatial characteristics of space. it is necessary to provide measurable scales in determining the level of permeability and wayfinding. the study identified three different scales: excellent, average, and poor, as shown in table 3. the research indicators identified in this paragraph are essential parameters in determining the users’ circulation within the educational space, which can be a reference for the level of effectiveness of social distancing. table 3 three scales for the level of permeability and wayfinding (authors) scale wayfinding permeability excellent the space has a higher average value of choice and intelligibility (900-600). the space has a higher average value of visual integration and connectivity (300-500). normal the space has a median average value of choice and intelligibility (600-300). the space has a median average value of visual integration and connectivity (100-300). poor the space has a lower average value of choice and intelligibility (300-0). the space has a lower average value of visual integration and connectivity (0-300). journal of sustainable architecture and civil engineering 2022/2/31 50 the space syntax analysis of models for designing educational spaces was carried out using (vga) and (ama). first, the analysis began to accurately interpret the results by measuring the visual integration, connectivity, choice, and intelligibility of each sample separately. then the values are represented by a quantitative table that includes; the design models, their numbers, and the values obtained from the analysis process (higher values are highlighted in red and lower values in blue and median values in orange). finally, the chart was used to compare the different models for educational spaces design in all samples in terms of permeability and wayfinding scales. this analysis was conducted as follows: analysis of first sample models in the first sample, the design of educational spaces was in six models in terms of shape, rectangular (x.1.1), and in terms of area; medium (x.2.2) and small (x.2.3) with three patterns to arrange furniture; linear (x.3.1), grid (x.3.2) and external-central (x.3.4). the results of this analysis are shown in table 4. results and analysis table 4 the analyses summarize the first sample models (authors) based on (vga&ama) design space model x.1.1 x.1.1 x.1.1 x.1.1 x.1.1 x.1.1 x.2.2 x.2.2 x.2.2 x.2.3 x.2.3 x.2.3 x.3.1 x.3.2 x.3.4 x.3.1 x.3.2 x.3.4 model numbers 1st 2nd 3rd 4th 5th 6th method space syntax attributes avg. avg. avg. avg. avg. avg. vga visual integration 11.46 10.6 11.75 12.82 13.91 11.38 vga connectivity 286.11 234.67 340.24 297.95 289.63 222.02 ama choice 745.65 702.95 375.82 510.06 411.2 182.81 ama intelligibility r2 r2 r2 r2 r2 r2 0.88472 0.975 0.964002 0.937947 0.94815 0.954353 analysis of second sample models in the second sample, the design of educational spaces was in six models; in terms of shape, they are octagonal (x.1.3) and rectangular-triangle corners (x.1.4). and in terms of the area, they are large (x.2.1), with three patterns to arrange furniture; linear (x.3.1), networked (x.3.2), and inner-central (x.3.5). the results of this analysis are shown in table 5. table 5 the analyses summarize the second sample models (authors) based on (vga&ama). design space model x.1.3 x.1.3 x.1.3 x.1.4 x.1.4 x.1.4 x.2.1 x.2.1 x.2.1 x.2.1 x.2.1 x.2.1 x.3.1 x.3.2 x.3.5 x.3.1 x.3.2 x.3.5 model numbers 1st 2nd 3rd 4th 5th 6th method space syntax attributes avg. avg. avg. avg. avg. avg. vga visual integration 11.61 11.908 12.67 14.43 11.86 57.43 vga connectivity 357.11 409.91 454.14 384.91 317.82 885.06 ama choice 895.977 1017.85 1613.57 896.56 599.87 1203.4 ama intelligibility r2 r2 r2 r2 r2 r2 0.887697 0.976593 0.987974 0.890721 0.961636 0.915676 51 journal of sustainable architecture and civil engineering 2022/2/31 analysis of third sample models in the third sample, the design of educational spaces was also in six models; in terms of shape, they are square (x.1.2) and part of a circle (x.1.5). and in terms of the area, they are medium (x.2.2), with three patterns to arrange furniture; linear (x.3.1), grid (x.3.2), and external-central (x.3.4). the results of this analysis are shown in table 6. table 6 the analyses summarize the third sample models (authors) based on (vga&ama) design space model x.1.2 x.1.2 x.1.2 x.1.5 x.1.5 x.1.5 x.2.2 x.2.2 x.2.2 x.2.2 x.2.2 x.2.2 x.3.1 x.3.2 x.3.4 x.3.1 x.3.2 x.3.4 model numbers 1st 2nd 3rd 4th 5th 6th method space syntax attributes avg. avg. avg. avg. avg. avg. vga visual integration 11.73 10.83 13.29 10.94 13.09 12.34 vga connectivity 380.4 334.13 504.51 280.74 284.42 237.39 ama choice 646.42 934.27 523.99 22.81 11.11 48.02 ama intelligibility r2 r2 r2 r2 r2 r2 0.887732 0.97588 0.962018 0.916647 0.916051 0.959171 according to the values obtained using (vag) in the space syntax analysis, as shown in tables 4, 5, 6. the lowest visual integration value was (10.6) for the second model in the first sample. and the median value of the visual integration was (14.43) for the fourth model in the second sample. in comparison, the highest value was (57.43) for the sixth model in the second sample. visual connectivity values, the lowest value was (222.02) for the sixth model in the first sample. and the median value of visual connectivity was (357.11) for the first model in the second sample. in comparison, the highest value was (885.06) for the sixth model in the second sample. this means that the sixth model in the second sample with the highest visual integration value is the same as the highest value for connectivity. this difference in visual integration and connectivity values between the models can be justified. because the sixth model in the second sample is less in-depth and has many points with direct visual contact within the space than the two models mentioned previously, as shown in fig. 6. therefore, creating an excellent visual extension and ample space for students’ circulation directly connected to the seating results from the space design. furthermore, this provided a large field of visibility that could increase the level of permeability, thus increasing the effectiveness of social distancing. fig. 6 the second sample 6th model: (a) visual integration graph, and (b) connectivity graph, (authors) based on (vga) (a) (b) 15 second sample. in comparison, the highest value was (885.06) for the sixth model in the second sample. this means that the sixth model in the second sample with the highest visual integration value is the same as the highest value for connectivity. this difference in visual integration and connectivity values between the models can be justified. because the sixth model in the second sample is less in-depth and has many points with direct visual contact within the space than the two models mentioned previously, as shown in fig. . therefore, creating an excellent visual extension and ample space for students’ circulation directly connected to the seating results from the space design. furthermore, this provided a large field of visibility that could increase the level of permeability, thus increasing the effectiveness of social distancing. as for the values obtained using (ama) in the space syntax analysis, as shown in tables (4), (5), (6), the lowest value for selection was (11.11) for the fifth model in the third sample. and the median value of choice was (646.42) for the first model in the third sample. in comparison, the highest value was (1613.57) for the third model in the second sample. the lowest value was (0.88472) for the first model in the first sample in intelligible values. and the median value for intelligibility was (0.93795) for the fourth model in the first sample. in comparison, the highest value was (0.98797) for the third model in the second sample. this means that the third model in the second sample with the highest choice value is the same as the highest value for intelligibility because this model has a high value of integration and connectivity. this case can be justified in the values of choice and clarity; in fact, the third model in the second sample is less deep and has many shortest paths that intersect directly between points within the space than the two models mentioned previously, as shown in fig. . therefore, more intelligible movement paths are provided in the users’ circulation area, leading to accessibility from the entry point to the seating and back, resulting from the space design. furthermore, this has provided an intelligibility flow of movement at a high level that can contribute to increasing the level of wayfinding and thus increasing the effectiveness of social distancing. (b) intelligibility (a) choice (b) (a) fig. 7. the second sample 3rd sample: (a) choice graph, and (b) intelligibility graph, (authors) based on (ama). fig. 6. the second sample 6th sample: (a) visual integration graph, and (b) connectivity graph, (authors) based on (vga). as for the values obtained using (ama) in the space syntax analysis, as shown in tables 4, 5, 6, the lowest value for selection was (11.11) for the fifth model in the third sample. and the median value of choice was (646.42) for the first model in the third sample. in comparison, the highest value was (1613.57) for the third model in the second sample. the lowest value was (0.88472) for the first model in the first sample in intelligible values. and the median value for intelligibility was (0.93795) for the fourth model in the first sample. in comparison, journal of sustainable architecture and civil engineering 2022/2/31 52 (a) choice (b) intelligibility fig. 7 the second sample 3rd model: (a) choice graph, and (b) intelligibility graph, (authors) based on (ama) fig. 8 a chart shows scales of permeability and wayfinding in all models (authors) depending on (vga & ama) 15 second sample. in comparison, the highest value was (885.06) for the sixth model in the second sample. this means that the sixth model in the second sample with the highest visual integration value is the same as the highest value for connectivity. this difference in visual integration and connectivity values between the models can be justified. because the sixth model in the second sample is less in-depth and has many points with direct visual contact within the space than the two models mentioned previously, as shown in fig. . therefore, creating an excellent visual extension and ample space for students’ circulation directly connected to the seating results from the space design. furthermore, this provided a large field of visibility that could increase the level of permeability, thus increasing the effectiveness of social distancing. as for the values obtained using (ama) in the space syntax analysis, as shown in tables (4), (5), (6), the lowest value for selection was (11.11) for the fifth model in the third sample. and the median value of choice was (646.42) for the first model in the third sample. in comparison, the highest value was (1613.57) for the third model in the second sample. the lowest value was (0.88472) for the first model in the first sample in intelligible values. and the median value for intelligibility was (0.93795) for the fourth model in the first sample. in comparison, the highest value was (0.98797) for the third model in the second sample. this means that the third model in the second sample with the highest choice value is the same as the highest value for intelligibility because this model has a high value of integration and connectivity. this case can be justified in the values of choice and clarity; in fact, the third model in the second sample is less deep and has many shortest paths that intersect directly between points within the space than the two models mentioned previously, as shown in fig. . therefore, more intelligible movement paths are provided in the users’ circulation area, leading to accessibility from the entry point to the seating and back, resulting from the space design. furthermore, this has provided an intelligibility flow of movement at a high level that can contribute to increasing the level of wayfinding and thus increasing the effectiveness of social distancing. (b) intelligibility (a) choice (b) (a) fig. 7. the second sample 3rd sample: (a) choice graph, and (b) intelligibility graph, (authors) based on (ama). fig. 6. the second sample 6th sample: (a) visual integration graph, and (b) connectivity graph, (authors) based on (vga). the highest value was (0.98797) for the third model in the second sample. this means that the third model in the second sample with the highest choice value is the same as the highest value for intelligibility because this model has a high value of integration and connectivity. this case can be justified in the values of choice and clarity; in fact, the third model in the second sample is less deep and has many shortest paths that intersect directly between points within the space than the two models mentioned previously, as shown in fig. 7. therefore, more intelligible movement paths are provided in the users’ circulation area, leading to accessibility from the entry point to the seating and back, resulting from the space design. furthermore, this has provided an intelligibility flow of movement at a high level that can contribute to increasing the level of wayfinding and thus increasing the effectiveness of social distancing. 16 fig. 6. a chart shows scales of permeability and wayfinding in all models (authors) depending on (avg & ama). as shown in fig. 6, measurements of the level of permeability and wayfinding can be determined. according to the above values of visual integration, connectivity, choice, and intelligibility, and the scales previously determined in the search indicators paragraph. so, this showed that the sixth model in the second sample had an excellent level of permeability. in opposite, the poor level of permeability was for the sixth model in the first sample. in comparison, the average level of permeability was in the first model in the second sample. as for the level of wayfinding, it showed that the third model in the second sample had an excellent level. in opposite, the poor level of the wayfinding for the fifth model. in comparison, the poor level of permeability was in the first model of the third sample. as a result, there are different scales of the level of permeability and wayfinding between the analysed models. this can be attributed to the difference in the values of visual integration, connectivity, and the value of choice and intelligibility for those spaces. finally, these research results can generally be invested in discussing the study’s most important findings to extract significant conclusions. discussion: educational space design: the educational space is a fixed place for students and staff to perform various educational functions. the design of these spaces was in different shapes and areas, and their differences in the pattern of arranging furniture. the analysis results of those different models showed many weaknesses in the inability of some space design models to facilitate compliance with social distancing, mainly models 4th, 5th, and 6th in the third sample, as shown in fig. 6. the main reason for this is the low level of spatial space characteristics, mainly due to the weak changing spatial relationships in the design of these different spaces in terms of the shape, space, and pattern of arranging furniture. this has led to the inability of a space design to reduce physical convergences between users, thus more gatherings of users simultaneously. impact of educational space design: the shape, area, and furniture arrangement pattern as spatial variables in space design have an essential effect in drawing the motor behavior of users as the circulation within space. for example, the shape of the educational space design features close longitudinal and transverse sides such as rectangular, square, and rectangular with triangular corners. this shape provides as shown in fig. 8, measurements of the level of permeability and wayfinding can be determined. according to the above values of visual integration, connectivity, choice, and intelligibility, and the scales previously determined in the search indicators paragraph. so, this showed that the sixth model in the second sample had an excellent level of permeability. in opposite, the poor level of permeability was for the sixth model in the first sample. in comparison, the average level of permeability was in the first model in the second sample. as for the level of wayfinding, it showed that the third model in the second sample had an excellent level. in opposite, the poor level of the wayfinding for the fifth model. in comparison, the poor level of permeability was in the first 53 journal of sustainable architecture and civil engineering 2022/2/31 model of the third sample. as a result, there are different scales of the level of permeability and wayfinding between the analysed models. this can be attributed to the difference in the values of visual integration, connectivity, and the value of choice and intelligibility for those spaces. finally, these research results can generally be invested in discussing the study’s most important findings to extract significant conclusions. discussion educational space design: the educational space is a fixed place for students and staff to perform various educational functions. the design of these spaces was in different shapes and areas, and their differences in the pattern of arranging furniture. the analysis results of those different models showed many weaknesses in the inability of some space design models to facilitate compliance with social distancing, mainly models 4th, 5th, and 6th in the third sample, as shown in fig. 8. the main reason for this is the low level of spatial space characteristics, mainly due to the weak changing spatial relationships in the design of these different spaces in terms of the shape, space, and pattern of arranging furniture. this has led to the inability of a space design to reduce physical convergences between users, thus more gatherings of users simultaneously. impact of educational space design: the shape, area, and furniture arrangement pattern as spatial variables in space design have an essential effect in drawing the motor behavior of users as the circulation within space. for example, the shape of the educational space design features close longitudinal and transverse sides such as rectangular, square, and rectangular with triangular corners. this shape provides intelligible motion paths parallel to the longitudinal sides of space and an appropriate visibility field from the entry to the farthest point directly connected to the seats. this means creating excellent spatial relationships that increase the level of permeability and wayfinding within space, thereby increasing the effectiveness of social distancing. an area in the educational space design and its impact on the effectiveness of social distancing depends on the proportion of the empty area (space available for students’ circulation) to the space area. the larger the proportion of empty area, the better the spatial relationships and the greater the spatial separation between seating seats. this means that increasing empty area in space design increases movement streamlining and accessibility to the intended point, thereby increasing the effectiveness of social distancing achieved by preventing or reducing the most physical contact points between users. the furniture arrangement pattern in the educational space design has an essential impact on the effectiveness of social distancing. that element defines the paths and direction of movement and the circulation mechanism and significantly affects the space’s spatial relationships. the linear and inner-central pattern streamlines intelligible movement and makes selecting the appropriate path to access the intended point. as a result, this achieves an excellent level of permeability, wayfinding, and reducing confusion and random intersections between users, thus increasing the effectiveness of social distancing. appropriate design: based on the analysis of different models for designing educational spaces, some indicators have emerged about the elements of designing the appropriate educational space from the spectrum of promoting compliance with social distancing. the study determined the appropriate educational space design for physical interaction between users with compliance with social distancing; in terms of space shape, rectangular or square shape, and terms space area, large area (200 m2), and more. as for the furniture arrangement pattern, linear or inner-central arrangement of furniture within the educational space, considering the functional performance criteria of the edjournal of sustainable architecture and civil engineering 2022/2/31 54 ucational space. finally, the study recommends some general guidelines that could enhance the effectiveness of social distancing within the educational space, as follows: _ adopt the flexible pattern of arranging furniture that works on the plains of changing the configuration of the place to suit the increased effectiveness of social distancing. _ space design in a shape and area encourages the implementation of a one-way internal movement path rather than the opposite direction to produce possible intersections between students in the circulation area. _ placing the place that meets temporary educational uses (short stay within the educational space) at a lower depth near the entry point, in contrast to the permanent uses. _ use spatial markers as a mentoring mechanism, especially in first-stage students’ educational spaces, to improve wayfinding and reduce indiscriminate movement within space. conclusion the study proved that there is an impact and a close relationship between elements of educational space design and the effectiveness of social distancing. the effect of the space shape is based on the possibility of providing intelligible movement pathways and an appropriate area of visibility. the impact of the area in space design is also manifested through the proportion of the empty area (space available for students’ circulation) to the space area. it controls movement streamlining and accessibility within space. while the furniture arrangement pattern has the most significant impact as it determines the direction of movement, the circulation mechanism, and the user’s points of presence within the space. the close relationship between the educational space design and the effectiveness of social distancing is formed by correlating the shape and area of the space and the furniture arrangement pattern in determining the movement and visual relations of the spatial configuration. these relations, in turn, impact the permeability and wayfinding as spatial characteristics that control the user’s circulation. the latter is one of the essential factors in the level of effectiveness of social distancing. after recent outbreaks of epidemics appear, the importance of conducting spatial analysis to assess the design of existing university buildings to reduce the spread of current and future epidemics. so, this study demonstrates the possibility of the syntax method in investigating the impact of educational space design in fostering social distancing, the space design in terms of the shape and area of the space, and the furniture arrangement pattern using the level of permeability and wayfinding. the study results support the possibility of usable educational spaces while complying with social distancing. in terms of the architectural design of the educational space, the study found that the space in the shape of a rectangle or square with a large area (200 m2) and more with a linear or inner-central pattern for arranging furniture, as a design for an educational space appropriate in promoting social distancing compliance. adopt the flexible pattern of arranging furniture with the appropriate shape and area for space design, taking into account the streamlining of movement and spatial arranging priorities for uses according to the appropriate depth and using guidance mechanisms to improve wayfinding. those can be future standards for designing educational spaces to reduce the spread of epidemics. as a recommendation for future studies, it is essential to evaluate data of furniture type, shape, dimensions, and even functions type (dynamic and static) and the potential number of space users. these variables can be addressed from the perspective of fostering social distancing in future research. 55 journal of sustainable architecture and civil engineering 2022/2/31 abdul nasir, n.a.b., hassan, a.s., khozaei, f. and abdul nasir, m.h. bin. investigation of spatial configuration management on social distancing of recreational clubhouse for covid-19 in penang, malaysia. international journal of building pathology and adaptation, 2021; 39(5): 782-810. https://doi. org/10.1108/ijbpa-08-2020-0072 alnusairat, s., al maani, d. and al-jokhadar, a. 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28(1): 103121. https://doi.org/10.1068/b2684 ugail, h., aggarwal, r., iglesias, a., howard, n., campuzano, a., suárez, p., maqsood, m., et al. 57 journal of sustainable architecture and civil engineering 2022/2/31 about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). social distancing enhanced automated optimal design of physical spaces in the wake of the covid-19 pandemic. sustainable cities and society, 2021; 68: 102791. https://doi.org/10.1016/j. scs.2021.102791 usman, m., lee, t.-c., moghe, r., zhang, x., faloutsos, p. and kapadia, m. a social distancing index: evaluating navigational policies on human proximity using crowd simulations. mig ‚20: motion, interaction and games, new york, 2020; 10: 1-6. https://doi.org/10.1145/3424636.3426905 who. considerations for public health and social measures in the workplace in the context of covid-19. world health organisation, 2020; 6. wilder-smith, a. and freedman, d.o. isolation, quarantine, social distancing and community containment: pivotal role for old-style public health measures in the novel coronavirus (2019-ncov) outbreak. journal of travel medicine, 2020; 27(2): 1-4. hhttps://doi.org/10.1093/jtm/taaa020 yun, y.w. and kim, y.o. the effect of depth and distance in spatial cognition. proceedings, 6th international space syntax symposium, i̇stanbul, 2007; 49: 1-13. zerouati, w. and bellal, t. evaluating the impact of mass housings: in-between spaces, spatial configuration on users, social interaction. frontiers of architectural research, 2020; 9(1): 34-53. https://doi. org/10.1016/j.foar.2019.05.005 ahmed m. hameed al-delfi postgraduate student university of technology iraq, architectural engineering department, baghdad, iraq main research area my research interests focus on architectural design and healthy buildings. address bismayah city, baghdad, iraq tel. +9647717389377 e-mail: 90136@uotechnology.edu.iq abdullah s. salman professor prof, university of technology iraq, architectural engineering department, baghdad, iraq main research area architectural design, architectural design theory, architectural ethics philosophy. address baghdad, iraq tel. +9647702924472 e-mail: abdullah.s.salman@uotechnology.edu.iq journal of sustainable architecture and civil engineering 2015/1/10 40 jsace 1/10 journal of sustainable architecture and civil engineering vol. 1 / no. 10 / 2015 pp. 40-49 doi 10.5755/j01.sace.10.1.9980 © kaunas university of technology received 2014/10/30 accepted after revision 2015 03 13 brutalism in poland on the example of the architecture of krakow wojciech niebrzydowski bialystok university of technology, faculty of architecture oskara sosnowskiego st. 11, 15-893 bialystok, poland brutalism in poland on the example of the architecture of krakow http://dx.doi.org/10.5755/j01.sace.10.1.9980 corresponding author: w.niebrzydowski@pb.edu.pl the impact of brutalism on polish architecture has not been recognized. therefore this academic problem still needs thorough researches. the relevant study results are presented in the article. they are claimed to be precursory and they bring new knowledge to the history of architecture in the 20th century. brutalist style became popular in western europe in the late 1950s, then spread all over the world and passed in the 1970s. brutalism in polish architecture was developed later than in the rest of the world and it did not become such a dominant trend as in other countries, however many elements and forms of this style could be also seen in poland. research conducted by the author in recent years led to formulation and classification of brutalist attributes and elements in world architecture. this systematics has become the base for further research of polish architecture. in this article, the author focuses on the architecture of krakow, i.e. the city, where brutalist influences were particularly evident. he has choosen five the most representative buildings from the period 1956–1989 and analyses their forms and spatial arrangement. after that the author describes the key features that connect examined buildings with brutalism, such as: heaviness, massiveness, severity, expressiveness, exhibition of construction and internal functions in architectural form, chiaroscuro effects. besides, the brutalist elements of the buildings are also examined; these include: three-dimensional facades, overhanging solids, rhythmically repeated modules, staircase towers, pedestrian bridges and courtyards, rough textures of concrete, brick and plaster. finally the author distinguishes several ways of devaluation of brutalist buildings, which are unfortunately evident in krakow. he emphasizes the great importance of the relevant architecture heritage protection, as the brutalist architecture is still underestimated in poland. keywords: brutalism, krakow, polish architecture, theory and history of architecture. introduction brutalism was present in the world-wide architecture from the end of the 1940s to the 1970s. it was born in great britain and was called new brutalism. its main advocates were architects alison and peter smithson and a critic and historian of architecture reyner banham. they were convinced of necessity to return to the roots of modernism and the deep reform of this trend. they also opposed to post-war tendencies which headed for decorative modernism called new humanism. the smithsons preferred raw aesthetics and simple forms and emphasised ethical values of architecture, such as sincerity in exposing materials and structure of building. a definition of new brutalism was included in three points by banham: “1, memorability as an image; 2, clear exhibition of structure; and 3, valuation of materials «as found»” (1955). according to werner nehls “new brutalism was the first step of the incoming anti-functional architecture” (1967). however it wasn’t evident in the forms of buildings designed by the smithsons at the time. this happened due to the fact that they were 41 journal of sustainable architecture and civil engineering 2015/1/10 looking for an architecture reflecting everyday life of english society after the end of the world war ii. life conditions were very difficult at that time and the period was marked by the post-war trauma. as anthony vidler writes “new brutalism was born out of the post-war culture of «austerity britain»” (2011) which marks could be seen in simple and severe forms of the first completed buildings. much more complex and expressive forms were designed in other countries which were reached by ideas of new brutalism. these ideas found favourable conditions but were stripped of the smithsons’ ethical assumptions. thus, new brutalism as a specific architectural ethic had not stood the test of time and transformed into architectural style. “as it became clear to banham [...] his desire to characterize and thereby establish a new ethic of architecture called new brutalism inevitably, in global dissemination, degenerated into a rough concrete style, married to the parallel fashion for megastructures in the quest for «new» monumentality. the ethic, he concluded [...] had indeed become no more than aesthetic.” (may 2013) another architect who had a particular impact on brutalist aesthetics was le corbusier. in his works, symptoms of the rejection of smooth, sterile aesthetics of the machine for the benefit of more complex structures and stronger articulation of solids, which create architectural form, could be already seen at the beginning of the 1930s. le corbusier considered that aesthetic doctrine of early modernism became too tight for him. in a way, he distanced from the ideas of functionalism. “my house is practical. i thank you, as i might thank railway engineers, or the telephone service. you have not touched my heart. but suppose that walls rise towards heaven in such a way that i am moved. i perceive your intentions. your mood has been gentle, brutal, charming or noble. the stones you have erected tell me so. [...] by the use of raw materials and starting from conditions more or less utilitarian, you have established certain relationships which have aroused my emotions. this is architecture.” (le corbusier 1927) le corbusier began to put form before function. he decided to create more sensual and expressive architecture, in which emotional experience played the leading role. he rejected white, box-like buildings for the benefit of sculptural, heavy forms, as it can be seen in unite d`habitation in marseille (1947-1952) and in many other of his post-war buildings. brutalist style became popular in western europe (france – le corbusier, switzerland – atelier 5, italy – vittoriano vigano, germany – oswald mathias ungers) in the 1950s, and then it reached japan with le corbusier`s students (kunio mayekawa, junzo sakakura, kenzo tange). later on, it was popularized in the usa (by louis kahn, marcel breuer and paul rudolph). it took on different forms in each of these countries, because “the nature of brutalism is not a universal entity, but actually quite a regionalist concept” (parnell 2012). in eastern europe, after the world war ii, socialist realism style reigned in the architecture, that is why brutalism reached these countries with a delay. however, after the period of architectural aesthetics being imposed by the communist authorities, designers took ideas from the west with euphoria. for example interesting, brutalist buildings appeared in former yugoslavia. after the earthquake in 1963, many concrete buildings were built in skopje, among which four brutalist skyscrapers were outstanding, namely, goce delcev dormitories, which were designed by georg konstantinovski, paul rudolph’s student. besides, brutalism left a stamp on the architecture of former czechoslovakia, especially after the prague spring in 1968. it reached also baltic republics, where cultural edifices and sport buildings were built in this style, e.g. the palace of sports in vilnius (designed by e. khlomauskas, j. kruklis, z. landsbergis, built in 1964). the aim of this article is to prove that brutalist trend was present also in poland. this issue was absent in former academic works, so far. neither the studies on architecture in the period of socialism focused on the problem of brutalism, nor the publications touched the subject matter, except of a few publications that included only a brief mention of the brutalist tendencies, as the book on the polish church architecture by konrad kucza-kuczynski (1991), or in the monograph about the architecture of krakow in the 1960s by malgorzata wlodarczyk (2006). notwithstanding, the city of krakow is journal of sustainable architecture and civil engineering 2015/1/10 42 particularly important for the development of brutalism in poland. therefore, brutalist tendencies in polish architecture are examined in the paper on the example of krakow. buildings in this style were built from the end of the 1950s to the 1980s. brutalist influences are evident in their forms, although some of the buildings presented in the article include also elements of other tendencies. five buildings, with different functions and built in different years, have been analysed. their features and elements showing the bonds with brutalism have been discussed. the author emphasizes also relationship between polish brutalist architecture and the general brutalist architectural movement in the world. he concludes how important is to protect the heritage of brutalism, which is still underestimated in poland and is often in poor condition. the author distinguishes several ways of devaluation of brutalist buildings, which are unfortunately evident in krakow. deeply rooted opinion that brutalism, as a style of the second part of the 20th century, had marginal meaning for the development of polish architecture, requires verification. however, this objective should be seen in a broader perspective on the global architecture of the period. therefore, the author of this article had studied literature on brutalism in different countries, including significant book of reyner banham “the new brutalism: ethic or aesthetic?” (1966), early articles of peter and alison smithson, monographs on the work of brutalist architects, the newest publications about brutalism (articles in “clog” and “october – mit magazine”, book by alexander clement) and many others. recent research conducted by the author led to formulation and classification of brutalist attributes and elements in architecture over the world. this systematics has become the base for further researches of polish architecture and comparative analysis. the main hypothesis assumes that brutalism in polish architecture was developed later then in the world and it did not become such a dominant trend as in western countries, but many elements and forms of this style are also visible in poland. the main aim of the author’s research is to determine the impact of brutalist style on projects and buildings of polish architects between 1956 and 1989. for the purpose of this article such comprehensive task was reduced to the brutalist architecture in krakow. the author has conducted appropriate research in situ and prepared photographic documentation of more than twenty buildings. after the analysis, based on the developed classification of brutalist elements, he has choosen five the most representative buildings from different years of the period under examination. due to the very limited literature on brutalism in poland he relied mainly on foreign literature and sought analogies between polish and international architecture. methods results after the world war ii, poland got under the influences of the soviet union. for architects, the period of stalinism meant the lack of creative freedom and implied the necessity of creating in the style imposed by the authorities. after the 20th congress of the communist party of the soviet union, the period of stalinism ended; and when boleslaw bierut, the communist president of poland, died, the breakthrough came in 1956. the so called “little stabilisation” and partly opening on the western culture and art came and proceed for the following years. polish architects eagerly came back to the ideas of pre-war modernism, which had been forbidden so far. they started to get the information about last tendencies in world-wide architecture, including brutalism, which was reflected in new designs and buildings. it was particularly evident in krakow, the former capital of poland and strong cultural center in the southern part of the country. many talented architects of older and younger generation gathered in this town after the world war ii. they were mostly connected with the faculty of architecture at the krakow university of technology. it was a dynamic university, opening to the world and maintaining many contacts with architects abroad. thanks to it, krakow became a city in the avant-garde of polish architecture. wlodarczyk notices the characteristic feature of those days architecture in krakow. “ideas were derived from european modernism close to brutalism, national italian school (neo-futuristic trend) and french school (neo-expressionism). there were not so many possibilities to design directly in the international style.” (2006) 43 journal of sustainable architecture and civil engineering 2015/1/10 polish architecture was in a difficult situation, despite the rejection of socialist realism, at the end of the 1950s. the role of architect in the socialist country was restricted. from architect-artist he became one of many participants of design-building process. primarily quantity and not quality was important in project offices, because they were categorized as manufacturing businesses. there was shortage of building materials and available ones were generally of poor quality. in addition, the flow of information and trade press from the west was limited and provided mainly through private channels. it seems significant that in the period of socialism none of le corbusier’s books was translated into polish. there should be a greater admiration for the architects who in those difficult times were trying to design original buildings and were guided by innovative ideas. the biprocemwap office building wojciech bulinski was one of those architects. in the years 1958–1960 he designed a big office building called biprocemwap, which was completed in 1963 (fig. 1). le corbusier’s influences can be seen in this building. bulinski wrote about his project: “this individual project was for a young architect (just four years after studies) ambitious and extremely difficult. i was fascinated by le corbusier’s architecture and used a «free facade» with the withdrawal of pillars inside and independent «free plan»” (bialkiewicz, kadluczka, zin 1995). the form of the building consists of three parts. the main block is located at a city square (now partly occupied by a building of a hotel) while the two side wings are parallel to adjacent streets. the main part is seven floors high while the wings reach height of five floors. in order that the side wings would not towered visually over adjacent, historic buildings, the highest floor was withdrawn. such an approach honouring the existing context was uncommon not only in poland but also in other countries. it is worth recalling that the global discussion on the role of context in urban environment was started by an american brutalist architect paul rudolph (moholy-nagy, rudolph, schwab 1970). the shape of the main block of biprocemwap was also a result of analyses of the surroundings. it is not an ordinary rectangular prism but it is slightly bent according to the course of morawskiego street. the ground floor differs from the higher floors because it is partially open (there are clear similarities to the icon of brutalism – unite d’habitation in marseille). the structural system of the building is exposed. round poles in the background and the raw of massive pillars, widening upward as corbusian pilotis, in the front can be noticed. the facade above is made of strips of glazing separated by the lines of ceilings. this horizontal pattern is divided by alternating rhythms of thin vertical ribs made of precast concrete. these elements resemble brise soleil or ondulatoires (used by le crobusier in the monastery of la tourette). the division of the interior into office rooms is reflected by the system of ribs. there is a pavilion with a coffee bar on the roof of the building. its form is dynamic thanks to curled canopy. the visible constructional and functional structure of building is a typical feature of the brutalist architecture. fig. 1 wojciech bulinski, the biprocemwap office building in krakow, 1958–1963 – view of the front facade [photo: w. niebrzydowski] channels. it seems significant that in the period of socialism none of le corbusier’s books was translated into polish. there should be a greater admiration for the architects who in those difficult times were trying to design original buildings and were guided by innovative ideas. 1. the biprocemwap office building wojciech bulinski was one of those architects. in the years 1958–1960 he designed a big office building called biprocemwap, which was completed in 1963 (fig. 1). le corbusier’s influences can be seen in this building. bulinski wrote about his project: “this individual project was for a young architect (just four years after studies) ambitious and extremely difficult. i was fascinated by le corbusier’s architecture and used a «free facade» with the withdrawal of pillars inside and independent «free plan»” (bialkiewicz, kadluczka, zin 1995). fig. 1. wojciech bulinski, the biprocemwap office building in krakow, 1958–1963 – view of the front facade [photo: w. niebrzydowski] the form of the building consists of three parts. the main block is located at a city square (now partly occupied by a building of a hotel) while the two side wings are parallel to adjacent streets. the main part is seven floors high while the wings reach height of five floors. in order that the side wings would not towered visually over adjacent, historic buildings, the highest floor was withdrawn. such an approach honouring the existing context was uncommon not only in poland but also in other countries. it is worth recalling that the global discussion on the role of context in urban environment was started by an american brutalist architect paul rudolph (moholy-nagy, rudolph, schwab 1970). the shape of the main block of biprocemwap was also a result of analyses of the surroundings. it is not an ordinary rectangular prism but it is slightly bent according to the course of morawskiego street. the ground floor differs from the higher floors because it is partially open (there are clear similarities to the icon of brutalism – unite d’habitation in marseille). the structural system of the building is exposed. round poles in the background and the raw of massive pillars, widening upward as corbusian pilotis, in the front can be noticed. the facade above is made of strips of glazing separated by the lines of ceilings. this horizontal pattern is divided by alternating rhythms of thin vertical ribs made of precast concrete. these elements resemble brise soleil or ondulatoires (used by le crobusier in the monastery of la tourette). the division of the interior into office rooms is reflected by the system of ribs. there is a pavilion with a coffee bar on the roof of the building. its form is dynamic thanks to curled canopy. the visible constructional and functional structure of building is a typical feature of the brutalist architecture. bulinski designed side facades in contrast to the front facade. they are partly massive and windowless. their grey texture is divided by recessed lines and resembles beton brut. in fact, it is a wall covered with a rough plaster. the architect applied this approach to induce the illusion of concrete surface. exposed concrete was rarely used in those days, mainly because of low quality of building services. grey cement plaster with thick aggregate became an ersatz of beton brut for polish brutalists. bulinski designed side facades in contrast to the front facade. they are partly massive and windowless. their grey texture is divided by recessed lines and resembles beton brut. in fact, it is a wall covered with a rough plaster. the architect applied this approach to induce the illusion of concrete surface. exposed concrete was rarely used in those days, mainly because of low quality of building services. grey cement plaster with thick aggregate became an ersatz of beton brut for polish brutalists. journal of sustainable architecture and civil engineering 2015/1/10 44 the municipal exhibition pavilion – bunker of art the first decade after the world war ii was a time of raising the country from ruins – reconstruction of industry and providing people with houses. after this period, the authorities decided that the time for facilities ensuring higher needs had come. the end of the 1950s and the beginning of the 1960s brought a mass construction of buildings of culture and art. architectural styles characterized by emotions and strong, individual forms, such as brutalism, were particularly appropriate. an interesting art gallery was built in krakow on this wave. the municipal exhibition pavilion was built within the historic centre of krakow and close to planty park. the project was made by krystyna rozyska-tolloczko in 1959, and the construction was completed in 1965. the building was built in the place of previously demolished historic structures. one of them (eighteenth-century tenement house) survived in a state of ruin, and rozyska-tolloczko decided to restore it and join in the form of new building. such an individual approach to design task was opposite to the modernist inclinations for universal solutions. the quest for “the unique solution to an unique situation” (banham 1966) was highlighted by many brutalist architects (paul rudolph in the project of the administrative centre of new heaven inserted large neo-gothic town hall in brutalist mega-structure). the form of the building is very simple – it is actually one large cuboid. two-thirds of the height of the solid is a windowless concrete wall, above which there is a strip of glazing, and the whole is crowned by a horizontal line of a flat roof. this structure is divided only by the facade of the surviving tenement house and its pitched roof covered with tiles. the architectural value of the building lies above all in the original texture and sophisticated details. the concrete surface of the facades is a work of art in itself. the sculptor antoni hajdecki helped in its design. the concrete walls were poured in specifically shaped formwork. horizontal formwork boards were set in different positions and trimmed in a different way. their imprint created a relief extending continuously through the entire building. three-dimensional treatment of the texture gave expressive result and interesting effect of chiaroscuro. brutalist architects indulged in experiments over the rough textures of the walls and often applied reliefs in concrete. the solution adopted in the pavilion in krakow stands out even among the best-known world examples. banham wrote about brutalism as “an architecture of massive plasticity and coarse surfaces” (1966) and this statement is confirmed by the pavilion. the only accents in the building are two entrances. “one of the entrance portals is a form of concave cutting into the reinforced concrete surface and suggesting that we are dealing with a large solid of concrete, the other one is convex, sophisticated form of a roof.” (kozlowski 2006) the sculptural canopy is particularly interesting and looks like a concrete, curved ribbon which smoothly flows into a bridge leading to the entrance (fig. 2). soft, smooth shapes of the roof contrast with the angular, rough texture of walls. the bridge was an element often used in brutalist architecture (e.g. the smithsons and their “street-decks”). fig. 2 krystyna rozyska– tolloczko, the municipal exhibition pavilion – bunker of art in krakow, 1959–1965 – the main entrance [photo: w. niebrzydowski] 2. the municipal exhibition pavilion – bunker of art the first decade after the world war ii was a time of raising the country from ruins – reconstruction of industry and providing people with houses. after this period, the authorities decided that the time for facilities ensuring higher needs had come. the end of the 1950s and the beginning of the 1960s brought a mass construction of buildings of culture and art. architectural styles characterized by emotions and strong, individual forms, such as brutalism, were particularly appropriate. an interesting art gallery was built in krakow on this wave. the municipal exhibition pavilion was built within the historic centre of krakow and close to planty park. the project was made by krystyna rozyska-tolloczko in 1959, and the construction was completed in 1965. the building was built in the place of previously demolished historic structures. one of them (eighteenth-century tenement house) survived in a state of ruin, and rozyska-tolloczko decided to restore it and join in the form of new building. such an individual approach to design task was opposite to the modernist inclinations for universal solutions. the quest for “the unique solution to an unique situation” (banham 1966) was highlighted by many brutalist architects (paul rudolph in the project of the administrative centre of new heaven inserted large neo-gothic town hall in brutalist mega-structure). the form of the building is very simple – it is actually one large cuboid. two-thirds of the height of the solid is a windowless concrete wall, above which there is a strip of glazing, and the whole is crowned by a horizontal line of a flat roof. this structure is divided only by the facade of the surviving tenement house and its pitched roof covered with tiles. the architectural value of the building lies above all in the original texture and sophisticated details. the concrete surface of the facades is a work of art in itself. the sculptor antoni hajdecki helped in its design. the concrete walls were poured in specifically shaped formwork. horizontal formwork boards were set in different positions and trimmed in a different way. their imprint created a relief extending continuously through the entire building. three-dimensional treatment of the texture gave expressive result and interesting effect of chiaroscuro. brutalist architects indulged in experiments over the rough textures of the walls and often applied reliefs in concrete. the solution adopted in the pavilion in krakow stands out even among the best-known world examples. banham wrote about brutalism as “an architecture of massive plasticity and coarse surfaces” (1966) and this statement is confirmed by the pavilion. the only accents in the building are two entrances. “one of the entrance portals is a form of concave cutting into the reinforced concrete surface and suggesting that we are dealing with a large solid of concrete, the other one is convex, sophisticated form of a roof.” (kozlowski 2006) the sculptural canopy is particularly interesting and looks like a concrete, curved ribbon which smoothly flows into a bridge leading to the entrance (fig. 2). soft, smooth shapes of the roof contrast with the angular, rough texture of walls. the bridge was an element often used in brutalist architecture (e.g. the smithsons and their “street-decks”). it was important to emphasize the aspect of movement and circulation of people. it was important to emphasize the aspect of movement and circulation of people. the municipal exhibition pavilion provoked great discussion. its avant-garde and distinctive form was a shock for the residents of krakow. they named the building “the bunker” (such comparisons are accompanied by many brutalist buildings in the world) and this term has clung to it permanently. today, the official name of the pavilion is bunker of art. 45 journal of sustainable architecture and civil engineering 2015/1/10 the polonia college building in the 1960s, brutalist style became extremely popular in architecture of universities in the west. this aesthetics was considered to be the most proper for such type of buildings, because it emphasized durability, power and dignity – attributes connected with knowledge and science. “received as architectural art, brutalist buildings were associated with creativity, individualism, and high intellectual and cultural achievefig. 3 dariusz kozlowski, tomasz mankowski, the polonia college building in krakow–przegorzaly, 1975–1983 – complex composition of the side facade [photo: w. niebrzydowski] fig. 2. krystyna rozyska–tolloczko, the municipal exhibition pavilion – bunker of art in krakow, 1959–1965 – the main entrance [photo: w. niebrzydowski] the municipal exhibition pavilion provoked great discussion. its avant-garde and distinctive form was a shock for the residents of krakow. they named the building “the bunker” (such comparisons are accompanied by many brutalist buildings in the world) and this term has clung to it permanently. today, the official name of the pavilion is bunker of art. 3. the polonia college building in the 1960s, brutalist style became extremely popular in architecture of universities in the west. this aesthetics was considered to be the most proper for such type of buildings, because it emphasized durability, power and dignity – attributes connected with knowledge and science. “received as architectural art, brutalist buildings were associated with creativity, individualism, and high intellectual and cultural achievement. likewise they were appreciated as challenging, enlivening environments able to invigorate the social and intellectual climate of the academic community.” (sroat 2005) this trend reached poland at the end of the 1960s. the polonia college building of the jagiellonian university in krakow-przegorzaly was built in the years 1975–1983 (fig. 3). it is one of the most distinctive examples of brutalism in poland, because it has exclusively brutalist features, without traces of other styles. tomasz mankowski and dariusz kozlowski were its designers. they did not hide their fascination with brutalist architecture – mankowski was louis kahn’s student and kozlowski admired british brutalists. the building consists of four wings, encircling the courtyard, which is the solution often encountered in brutalist architecture. precursors of brutalism were fascinated by centripetal arrangements, as exemplified by the smithsons’s, john voelcker’s, leslie martin’s and colin st. john wilson’s projects. the courtyard is a reflection of the idea of a common space, where social contacts cumulate like in the ancient forum. according to the ideas of brutalism, mankowski and kozlowski showed the internal functional structure in the form of the building, especially the circulation routes. staircases were pulled out from the wings of the building and placed in the vertical solids. the entrance to the courtyard was emphasised by the outer reinforced concrete bridge. rooms for other functions were also articulated in the facades. “separated forms – blocks of rooms with loggias and bay windows, galleries, staircases, housing clusters, halls, auditorium room – create the composition of the building.” (kozlowski 2001) in addition, a monolithic reinforced concrete structure, which elements – pillars and beams – were cutting the brick walls, was exposed in facades of the building. however, the form of the building is shaped mainly by articulated angular solids. they are arranged in such a way, that they form deep offsets, both horizontally and vertically. due to differences in the height of each part of the building, its silhouette has dynamic line. the composition of the facade is vertical in character. freedom in combination of different elements of the form, gave the effect of irregularity and picturesqueness, which many brutalist architects were searching for. ment. likewise they were appreciated as challenging, enlivening environments able to invigorate the social and intellectual climate of the academic community.” (sroat 2005) this trend reached poland at the end of the 1960s. the polonia college building of the jagiellonian university in krakow-przegorzaly was built in the years 1975–1983 (fig. 3). it is one of the most distinctive examples of brutalism in poland, because it has exclusively brutalist features, without traces of other styles. tomasz mankowski and dariusz kozlowski were its designers. they did not hide their fascination with brutalist architecture – mankowski was louis kahn’s student and kozlowski admired british brutalists. the building consists of four wings, encircling the courtyard, which is the solution often encountered in brutalist architecture. precursors of brutalism were fascinated by centripetal arrangements, as exemplified by the smithsons’s, john voelcker’s, leslie martin’s and colin st. john wilson’s projects. the courtyard is a reflection of the idea of a common space, where social contacts cumulate like in the ancient forum. according to the ideas of brutalism, mankowski and kozlowski showed the internal functional structure in the form of the building, especially the circulation routes. staircases were pulled out from the wings of the building and placed in the vertical solids. the entrance to the courtyard was emphasised by the outer reinforced concrete bridge. rooms for other functions were also articulated in the facades. “separated forms – blocks of rooms with loggias and bay windows, galleries, staircases, housing clusters, halls, auditorium room – create the composition of the building.” (kozlowski 2001) in addition, a monolithic reinforced concrete structure, which elements – pillars and beams – were cutting the brick walls, was exposed in facades of the building. however, the form of the building is shaped mainly by articulated angular solids. they are arranged in such a way, that they form deep offsets, both horizontally and vertically. due to differences in the height of each part of the building, its silhouette has dynamic line. the composition of the facade is vertical in character. freedom in combination of different elements of the form, gave the effect of irregularity and picturesqueness, which many brutalist architects were searching for. kozlowski believed that “for brutalism there was nothing more natural than the brick” (2001). brownish-red bricks with deep welds form a rough texture of most of walls. alhough, the smooth concrete is equally important textural material, which contrasts with the brick walls. it is used in elements which require to be emphasised. an overhanging reinforced concrete bay window is the most important of these elements. it is used as a repeatable module, enabling architects to obtain varied rhythms on the facades. the monolithic structure of the bay window is made of reinforced concrete poured into a steel form. massiveness and almost defensive character typifies the building. the significant thickness of the walls is highlighted by deep installation of windows. some of them are just narrow slits, which an observer reads as cracks, a dark voids in the wall. journal of sustainable architecture and civil engineering 2015/1/10 46 the aesthetic principle of “solid – void” was often used in brutalist architecture. the interiors of the buildings are similarly raw. the same brick dominates there, and the brutalist character is highlighted by industrial lamps and electrical cables running on the surface of the walls. the church of saint jadwiga the queen during the first decades after the war the authorities tried to fight manifestations of religious life, that is why they did not give permissions to build new churches. the brutalist aesthetics became characteristic of the great wave of polish sacral architecture, which came in the early 1970s. it was not restricted to the construction of churches, but additional buildings with various functions (educational, cultural, sports) were also built. thanks to this, parish centres appeared, which “aim was to maintain local activities and gather artistic and intellectual elites” (bialkiewicz, kadluczka, zin 1995). the church of saint jadwiga the queen was such a multi-centre, built in the years 1979–1988 according to romuald loegler’s and jacek czekaj’s project. the building is an example of late modernism in which brutalist aesthetics was juxtaposed with elements of high-tech. this combination is typical for the final phase of brutalism in the west. during the design, loegler and czekaj applied “a method based on the spatial concept of cube as a symbol of order” (szafer 1988), involving the adaptation of a cube as a parent module from which the whole architectural concept arises. this method was clearly reflected in the form of the church and its interior. the main solid of the church consists of “quarters of a cube, diagonally cut and adjoined with glazing at vertical edges and skylights on the roof at the horizontal edges. the presbytery is emphasised by two of these parts elevated above” (kucza-kuczynski 1991). thus, the form of the church is a cube, which is deconstructed, broken into smaller fragments and bonded by glazing continuing throughout the building. the building is dynamic thanks to this deconstruction, however large surfaces of concrete walls make the impression of severity and monumentality. despite the fact that the main axis of the church runs diagonally, the main entrance is placed in the side facade. this facade was designed differently than the others – its wall waves in a very expressive way and there grows out a slender belfry in the shape of a cylinder (fig.4). shapes of squares (on the ceiling) and circles (holes in the railing of the choir) appear in the interior. it is worth recalling that these basic geometric figures and solids (such as cube and cylinder) are the elements which louis kahn applied favourably in his brutalist buildings. another aspect characteristic of the brutalism is treating the building as a concrete sculpture and highlighting the circulation elements. the church of saint jadwiga the queen stands on a large pedestal like an exhibit in a museum and monumental stairs and ramps lead to it. a homogeneous texture of the facades bonds the fragmented form of the building. it is beton brut in a pure form. concrete surfaces were formed in fig. 4 romuald loegler, jacek czekaj, the church of saint jadwiga the queen in krakow, 1979–1988 – front view [photo: w. niebrzydowski] fig. 4. romuald loegler, jacek czekaj, the church of saint jadwiga the queen in krakow, 1979– 1988 – front view [photo: w. niebrzydowski] shapes of squares (on the ceiling) and circles (holes in the railing of the choir) appear in the interior. it is worth recalling that these basic geometric figures and solids (such as cube and cylinder) are the elements which louis kahn applied favourably in his brutalist buildings. another aspect characteristic of the brutalism is treating the building as a concrete sculpture and highlighting the circulation elements. the church of saint jadwiga the queen stands on a large pedestal like an exhibit in a museum and monumental stairs and ramps lead to it. a homogeneous texture of the facades bonds the fragmented form of the building. it is beton brut in a pure form. concrete surfaces were formed in the moulds of narrow and short boards which were set vertically. wood grains and joints of the boards are clearly visible. the texture gives raw and clumsy impression and it was contrasted with the smoothness and high-tech of glazing and skylights. two side wings of low buildings with a rectory, catechetical rooms, a cultural centre, a sport club and facilities of sisters of nazareth are adjacent to the cube of the church. between the church and the side buildings, the courtyard was designed. it has become an important gathering place for people. 5. the forum hotel the last example of brutalist architecture in krakow is the forum hotel, which construction was very long and extended from 1974 to 1988 (fig. 5). it was designed by the team led by janusz ingarden. the forum hotel was for the authorities of krakow a prestigious building. it was supposed to be the largest of its kind and also the most modern in the city. brutalist style was considered as the most appropriate to emphasize the individuality and importance of the building which should become a modern landmark of the city. the selection of the hotel’s location wasn’t accidental. it was built in a prominent place at the vistula river, in a short distance from the wawel royal castle. the building is a kind of megastructure – 110 meters long and about 40 meters high. its form is bent according to the shoreline of the river. the main block is raised high above the ground on several vertical service towers (concrete pillars are hidden in the structure of the towers). the construction of a hanging platform (massive reinforced concrete beams and slabs), on which other floors are set, is exposed. the northern facade, from the side of the river, is less expressive due to the horizontal composition (strips of windows and walls). whereas, the southern side of the building is extremely expressive and dynamic. three towers divide the main block. the middle one is the most massive and has a distinctive, convex window. the facade is three-dimensional – composed of repeating units (hotel rooms). these rectangular modules are twisted and overhung. the articulation of overhanging elements is one of the attributes of brutalism. on the roof there is a cafe pavilion, which form additionally diversifies the silhouette of the building. under the main block, there are pavilions with an entrance hall, restaurants and shops. their walls of glass are in contrast with grey rough plaster on the building. the moulds of narrow and short boards which were set vertically. wood grains and joints of the boards are clearly visible. the texture gives raw and clumsy impression and it was contrasted with the smoothness and high-tech of glazing and skylights. two side wings of low buildings with a rectory, catechetical rooms, a cultural centre, a sport club and facilities of sisters of nazareth are adjacent to the cube of the church. between the church and the side buildings, the courtyard was designed. it has become an important gathering place for people. 47 journal of sustainable architecture and civil engineering 2015/1/10 fig. 5 janusz ingarden, the forum hotel in krakow, 1974–1988 – view from the south [photo: w. niebrzydowski] fig. 5. janusz ingarden, the forum hotel in krakow, 1974–1988 – view from the south [photo: w. niebrzydowski] the forum hotel resembles japanese metabolism and buildings of architects such as kenzo tange, kiyonori kikutake and kisho kurokawa. in the 1970s a slogan “we are building the second japan” was popular in poland, which was trying to catch up economically developed countries. probably, that is why the influences of architecture from asia are so clear in forum. the hotel was used only for 14 years (that is as long as its construction lasted) and was closed in 2002. discussion on the basis of analyses of krakow buildings’ forms the key features and elements connecting them with brutalism can be distinguished. referring to banham`s definition of new brutalism, it can be concluded that the analysed buildings meet all three conditions. first, they expose their construction – pillars, beams, bearing walls, slabs. second, they utilize materials in accordance with the principle of “as found” showing raw surfaces of concrete or brick. the biprocemwap building and the forum hotel are the exceptions, where an aesthetic role of rough concrete plays grey, coarse plaster. third, every building is distinctive and memorable – is an unified visual image. in the forms of the buildings, not only the load bearing structure but also the internal, functional structure is seen. in biprocemwap the system of offices reflects the rhythm of brise soleil, in the forum hotel rooms are in the form of overhanging rectangular modules, and staircases are placed in the towers. there are staircases in vertical solids at the polonia college building, and the rooms are accented by reinforced concrete bay windows. the importance of a presbytery and an altar in the church of saint jadwiga the queen was highlighted by making the form higher. brutalists particularly emphasized the role of circulation and movement of people. it can be seen in the forms of buildings and their surroundings. “through walkways, plazas, terraces, and useable rooftops, which were frequently characteristic of brutalist buildings and were often paved in the same concrete or brick material as the buildings themselves, architects believed they were shaping engaging environments that would revive public life.” (sroat 2005) the same happens in the buildings in krakow – there are useable roofs in biprocemwap and forum, courtyards in polonia college and the church, bridges in bunker of art and polonia college. forms of the buildings are complex, expressive and sculptural. they are shaped in a way that encourages people to watch them from different points, forcing curious observers to move around them. they look interestingly, even from a distance, due to the dynamic shapes. the facades of the buildings are three-dimensional, shaped by coming forward and backward solids, overhanging elements and rhythmically repeated modules. such sculptural solutions of the facades provide expressive chiaroscuro effects. the play of light and shadow is also visible in the micro scale on rough textures of the walls, especially on the concrete relief of bunker of art, beton brut of the forum hotel the last example of brutalist architecture in krakow is the forum hotel, which construction was very long and extended from 1974 to 1988 (fig. 5). it was designed by the team led by janusz ingarden. the forum hotel was for the authorities of krakow a prestigious building. it was supposed to be the largest of its kind and also the most modern in the city. brutalist style was considered as the most appropriate to emphasize the individuality and importance of the discussion building which should become a modern landmark of the city. the selection of the hotel’s location wasn’t accidental. it was built in a prominent place at the vistula river, in a short distance from the wawel royal castle. the building is a kind of megastructure – 110 meters long and about 40 meters high. its form is bent according to the shoreline of the river. the main block is raised high above the ground on several vertical service towers (concrete pillars are hidden in the structure of the towers). the construction of a hanging platform (massive reinforced concrete beams and slabs), on which other floors are set, is exposed. the northern facade, from the side of the river, is less expressive due to the horizontal composition (strips of windows and walls). whereas, the southern side of the building is extremely expressive and dynamic. three towers divide the main block. the middle one is the most massive and has a distinctive, convex window. the facade is three-dimensional – composed of repeating units (hotel rooms). these rectangular modules are twisted and overhung. the articulation of overhanging elements is one of the attributes of brutalism. on the roof there is a cafe pavilion, which form additionally diversifies the silhouette of the building. under the main block, there are pavilions with an entrance hall, restaurants and shops. their walls of glass are in contrast with grey rough plaster on the building. the forum hotel resembles japanese metabolism and buildings of architects such as kenzo tange, kiyonori kikutake and kisho kurokawa. in the 1970s a slogan “we are building the second japan” was popular in poland, which was trying to catch up economically developed countries. probably, that is why the influences of architecture from asia are so clear in forum. the hotel was used only for 14 years (that is as long as its construction lasted) and was closed in 2002. on the basis of analyses of krakow buildings’ forms the key features and elements connecting them with brutalism can be distinguished. referring to banham`s definition of new brutalism, it can be concluded that the analysed buildings meet all three conditions. first, they expose their construction – pillars, beams, bearing walls, slabs. second, they utilize materials in accordance with the principle of “as found” showing raw surfaces of concrete or brick. the biprocemwap building and the forum hotel are the exceptions, where an aesthetic role of rough concrete plays grey, coarse plaster. third, every building is distinctive and memorable – is an unified visual image. in the forms of the buildings, not only the load bearing structure but also the internal, functional structure is seen. in biprocemwap the system of offices reflects the rhythm of brise soleil, in the forum hotel rooms are in the form of overhanging rectangular modules, and staircases are placed in the towers. there are staircases in vertical solids at the polonia college building, and the rooms are accented by reinforced concrete bay windows. the importance of a presbytery and an altar in the church of saint jadwiga the queen was highlighted by making the form higher. journal of sustainable architecture and civil engineering 2015/1/10 48 brutalists particularly emphasized the role of circulation and movement of people. it can be seen in the forms of buildings and their surroundings. “through walkways, plazas, terraces, and useable rooftops, which were frequently characteristic of brutalist buildings and were often paved in the same concrete or brick material as the buildings themselves, architects believed they were shaping engaging environments that would revive public life.” (sroat 2005) the same happens in the buildings in krakow – there are useable roofs in biprocemwap and forum, courtyards in polonia college and the church, bridges in bunker of art and polonia college. forms of the buildings are complex, expressive and sculptural. they are shaped in a way that encourages people to watch them from different points, forcing curious observers to move around them. they look interestingly, even from a distance, due to the dynamic shapes. the facades of the buildings are three-dimensional, shaped by coming forward and backward solids, overhanging elements and rhythmically repeated modules. such sculptural solutions of the facades provide expressive chiaroscuro effects. the play of light and shadow is also visible in the micro scale on rough textures of the walls, especially on the concrete relief of bunker of art, beton brut of the church and brick surfaces of polonia college. not all textures are rough – smooth concrete or glass is in contrast with them. the aesthetic principle of contrast is not only seen in the way of combining materials but also in the general approach in shaping the architectural form. it is worth noticing that in bunker of art and the church, architects opposed the dominant, rectilinear geometry to curvilinear geometry, just to accentuate entrances to the buildings. furthermore, all buildings in krakow present the basic aesthetic features attributed to the brutalist architecture: heaviness, massiveness, severity, monumentality. their designers were trying to take into account the context in which they were designing, and were aspiring to an individual, unique solution. some of the discussed buildings have brutalist features as well as elements of other styles, what is in general characteristic of polish architecture. world architectural ideas flowed to the socialist poland with a delay and with more or less difficulties. typically, they were not adopted in the pure form but mixed with other doctrines or changed due to local conditions. in poland, the brutalist style did not develop as much as in the west and the number of buildings completed here is not too large. the most interesting of them should be preserved due to their architectural values and testimony of a bygone era. the problem is the negative public perception of such buildings and the resistance of the authorities and some architects in considering their value. nowadays, brutalist buildings are threatened by various actions changing their form or by demolitions. paradoxically, less expressive structures which are more neutral, not thumping over stamp-solutions, have more chances to survive. in the case of brutalist architecture in krakow, there can be distinguished several ways of devaluation of noticeable buildings, from relatively “mild” to the totally devastating: 1 in recent years, covering the facades of buildings with commercials, including large format banners, has become notorious. it leads to a total illegibility of architectural forms. the disused forum hotel has become the biggest advertising board in poland. huge billboards cover its entire northern facade and side walls. 2 buildings, which were closing major view axes or were clearly exposed in the urban landscape, have been hidden behind new structures, often presenting much lower architectural values. the biprocemwap building was obscured by a new hotel built in front of its facade. “from the vistula river and kosciuszko street deflection of the office building, its modernist yet articulated facade, butterfly roof of the pavilion are no longer visible, … hello sadness.” (urbanska 2003) bunker of art has become obscured by the structure of new coffee bar which does not fit into brutalist style of the building. 3 the rebuilding often changes and distorts the original form of the buildings. sometimes relatively small changes, such as replacement of windows or plastering the concrete conclusions 49 journal of sustainable architecture and civil engineering 2015/1/10 wojciech niebrzydowski assistant prof., phd architect bialystok university of technology, faculty of architecture, department of housing architecture main research area theory and history of architecture in the 20th century, brutalism, housing architecture address oskara sosnowskiego st. 11, 15-893 bialystok, poland tel. +48 503 045 722 e-mail: w.niebrzydowski@pb.edu.pl surfaces affect the character of architecture. sacral buildings are generally kept in a state close to the original one but there are also changes – raw concrete of the church of saint jadwiga the queen disappeared under layers of paint. 4 often, the final step before the demolition of the building is its negligence leading to ruin. the forum hotel is practically disused and decaying. for several years there has been a discussion about the possibility of its demolition. 5 fortunately, the demolitions have not affected brutalist buildings in krakow, but in nearby katowice, the perfect example of polish brutalism – the railway station (designed by j. mokrzynski, w. klyszewski, w. wierzbicki, built in the years 1969–1973) was demolished, despite many protests of architects and historians. nowadays, not many polish buildings from the second half of the twentieth century are listed as historical monuments. however, architects and authorities, have a chance to identify buildings that should be protected as so called “goods of contemporary culture”. the era of brutalism passed away, but it is expected that the most of interesting buildings demonstrating the presence of this style in architecture will survive. banham r. the new brutalism. the architectural review, 1955; vol. 118 (december): 354-361. banham r. the new brutalism: ethic or aesthetic?. new york – stuttgart: reinhold publishing corporation – karl krämer verlag; 1966. bialkiewicz z.j., kadluczka a., zin b. (eds) prace polskich architektów na tle kierunków twórczych w architekturze i urbanistyce w latach 1945–1995 [works of polish architects on the background of creative directions in architecture and urban planning in the years 1945-1995]. krakow: wa pk; 1995. kozlowski d. nowy brutalizm w krakowie, albo prawda architektury kolegium polonijnego uj [new brutalism in krakow or the truth of the architecture of polonia college of the jagiellonian university]. polski cement, 2001; vol. 15 (3): 8-9, 36. kozlowski d. (ed.) architektura betonowa 2006 [concrete architecture 2006]. krakow: polski cement; 2006. kucza-kuczynski k., nowe koscioly w polsce [new churches in poland]. warszawa: instytut wydawniczy pax; 1991. le corbusier. towards a new architecture. london: architectural press; 1927. referencesmay k. (ed.) brutalism. canada: clog; 2013. moholy-nagys., rudolph p., schwab g. the architecture of paul rudolph. new york – washington: praeger publishers; 1970. nehls w., new brutalism: beginn einer neuen epoche. baumeister, 1967; jg. 64 (1): 75-85. parnell s. brute forces. architectural review, 2012; vol. 231 (6): 18-19. sroat h. brutalism: an architecture of exhilaration. paper presented at the conference paul rudolph symposium, university of massachusetts dartmouth; 13 april 2005. szafer t.p. współczesna architektura polska [polish modern architecture]. warszawa: arkady; 1988. urbanska m.a. krakow en face: w poszukiwaniu straconego modernizmu [krakow en face: in search of lost modernism]. a&b, 2003; vol. 129 (4): 72-75. vidler a. another brick in the wall. october – mit magazine, 2011; vol. 136 (1): 105-132. wlodarczyk m. architektura lat 60-tych w krakowie [architecture in the sixties in krakow]. krakow: wydawnictwo wam; 2006. about the author 5 journal of sustainable architecture and civil engineering 2022/1/30 *corresponding author: etousi@uniwa.gr urban acupuncture as a method of open space regeneration in greek ex-refugee areas.the case of nikea, piraeus received 2021/07/13 accepted after revision 2022/03/17 journal of sustainable architecture and civil engineering vol. 1 / no. 30 / 2022 pp. 5-18 doi 10.5755/j01.sace.30.1.29423 urban acupuncture as a method of open space regeneration in greek ex-refugee areas.the case of nikea, piraeus jsace 1/30 http://dx.doi.org/10.5755/j01.sace.30.1.29423 evgenia tousi, maro sinou, antonia peroul university of west attica, school of applied arts and culture, department of interior architecture introduction abstract the paper explores the potential of implementing the principles of urban acupuncture in a selected greek case study, taking into account international experience in the field. the research includes literature review and field work. the area of study is nikea, an ex-refugee urban area in the attica metropolitan region. it was founded during the 1930s to host refugees from asia minor. the initial hippodamian grid offers beneficial intermediate communal spaces inside each city block and there are also larger green spaces in proximity. however, the area suffers from urban blight owed largely to the poor quality of preservation of the old refugee housing estates. a mixture of factors contributes to the complex contemporary situation characterized by opportunities and challenges. on the one hand, there is great potential for regenerating the existing intermediate communal spaces and on the other decaying refugee houses and vulnerable households intricate the already convoluted situation. the paper provides cartographic depiction and categorization of the existing open spaces highlighting also contemporary socio-spatial challenges and market driven limitations. the research describes the obstacles that hinder the activation of “urban sensitive points” in terms of urban acupuncture, also advocating for possible solutions. the paper opens dialogue on the greek case study in terms of urban acupuncture with the view to suggest strategies to foster socio-spatial cohesion in degraded ex -refugee urban areas. this is a pilot case study with further application in other post-refugee urban areas in greece that share common socio-spatial attributes. thus, the topic of the paper may have a greater impact within the greek urban context. keywords: sustainability, urban acupuncture, urban planning, greece, ex-refugee urban areas. urban acupuncture focuses on small scale neuralgic interventions with direct impact on urban morphology and microclimate. taking into account a variety of factors, from socio-cultural context to environmental upgrade, urban acupuncture contributes to the creation of functional public spaces. according to literature, the micro-grids of urban acupuncture challenge conventional infrastructural planning and design (apostolou, 2015). with plenty of locally oriented experimental approaches, international experience outlines the significance of small-scale interventions; they are envisaged as key-generators for changing urban surroundings. from this point of view, urban acupuncture is considered to be a holistic socio-environmental theory that goes from micro to macro. in particular, the healing of nodal urban points may progressively transform the whole urban fabric (ibid). the origins of the concept derive from the traditional method of acupuncjournal of sustainable architecture and civil engineering 2022/1/30 6 ture. the main idea revolves around the application of pressure on specific points of the body so as to ameliorate health conditions. similarly, well-targeted small-scale projects find analogies with this healing method, aiming at the relief of the built environment (daugelaite and grazuleviciute-vileniske, 2018). based on localized approaches, urban acupuncture introduces the perception of the city as a living organism. this means that urban regeneration will be achieved through the remediation of urban parts. these interventions may be both individual and systematic, comprehended as a network of urban points or dots. international literature offers a variety of examples and case studies in the realm of urban acupuncture and tactical urbanism. these terms are not synonyms, yet they employ similar practices. the work of the pioneering architect marco casagrande, the theoretical work of j.lerner and the work of iaconesi and persico, focusing on emotional landmarks and digital urban acupuncture (iaconesi and persico, 2014) could be perceived as important theoretical and practical contributions. moreover, the dotank in brooklyn, new york, the “labplatz” project in berlin (2012) and the international movement of “chair bombing” are some of the most influential tactical urbanism initiatives. as far as greece is concerned, there are only rare initiatives in the field of urban acupuncture. one such example is the program “this is athens-πολη²” implemented in the municipality of athens, the capital of greece. the program offers financial support to collaborative initiatives so as to improve urban infrastructure and microclimate conditions. the interventions include among others, urban agriculture facilities, vertical urban gardens, green corridors and pocket parks, artificial lighting of public spaces with the help of renewable energy technologies and eco-friendly urban furniture. furthermore, academic dialogue on the issue has clarified the importance of urban acupuncture for greek cities so as to combat climate change and thermal heat island in metropolitan areas (agathangelidis, et.al., 2020 and santamouris et.al., 2018). urban green might prove beneficial for the improvement of the local microclimatic conditions in a megacity like athens (papangelis at.al, 2012). on account of these techniques, this paper explores the potentialities and challenges of the implementation of urban acupuncture analyzing a greek case study, taking into consideration the specificities of the greek urban development. the area of focus is a typical ex-refugee urban area in attica, designed during the 30s for the rehabilitation of the refugee population after the asia minor catastrophe in 1922. apart from the metropolitan attica region, refugee settlements are found also in many urban areas of greece. based on their initial urban design, the majority of these areas has open spaces inside each city block and pedestrian corridors that connect the blocks to each other. local residents use these spaces in various ways, giving them a semi-private semi-public sense. these open spaces could function as a springboard for further development. speaking about the area of focus, the presence of many scattered open spaces was the motive to explore the urban acupuncture potential, taking into account possible key-obstacles. in particular, field work analysis provided useful pieces of information not only for the barriers but also for the beneficial factors that facilitate the urban acupuncture perspective. the ultimate purpose of the paper is to open scientific dialogue on greek case studies, suggesting possible ways to overcome the barriers that impede the implementation of urban acupuncture. methods research is based on literature review and field work. research stages are illustrated in figure 1. delving into international literature, authors have identified the value of strategic small-scale interventions in order to regenerate a blighted urban district. furthermore, literature review includes pieces of information related to the multiple forces that shaped greek metropolitan areas, highlighting local specificities. in particular, authors studied the interwar refugee rehabilitation and the postwar urbanization in greece. the main research questions include: 7 journal of sustainable architecture and civil engineering 2022/1/30 _ the identification of the sensitive points of the area in terms of urban acupuncture, meaning the urban spots that could provide a greater positive impact if regenerated according to citizens needs _ the key-obstacles that hinder the activation of the “sensitive urban points” of the area in terms of urban acupuncture. to answer these questions field work was an important stage of the research, since these topics are not covered in pertinent literature. to be more specific, field work is divided into three stages. the first stage included identification of the “sensitive urban points” of the area as well as cartographic depiction of all the available open spaces in the municipality of nikea, while the second comprise categorization of the sites. for the categorization of the sites, critical parameters were the size of the site, the neighboring land uses and the presence or absence of decayed refugee housing complexes. during the third stage, authors delved into the key-obstacles as derived from direct observations. mapping and photographic documentation were used as tools for describing the factors that have detrimental effect on the urban acupuncture perspective. finally, regarding the above-mentioned material, authors identified the positive attributes of the selected case study that may facilitate the implementation of tactical urbanism. the methodology presented here might be suitable for other post-refugee urban areas in greece, that share common attributes with the selected case study. fig. 1 research scheme, authors’ work urban acupuncture and tactical urbanism: their potential impact on the greek case study urban acupuncture represents the “extra-small”, a notion contradictory to “extra-large” that prevailed during the previous decades. extra-large projects are connected with top-down, high-tech monoculture protocols while extra-small usually with bottom-up decentralized, often low-cost projects (lydon and garcia, 2015). the term was coined by manuel de sola-morales (1999) a spanish architect who focused on minimum interventions that achieve maximum effect. his work on the “urban skin” paved the way for further application of the method. following his example, other architects and urban planners like marco casagrande and jaime lerner became key-advocates of the urban acupuncture method as an effective approach to ameliorate urban stress. urban acupuncture is presented also as a method to surpass economic impediments and to lessen bureaucratic requirements (balicka et.al, 2021). as a fast-track planning method, urban acupuncture includes projects able to trigger direct upgrade in the quality of the adjacent enclaves. to identify these crucial urban spots, the so called “sensitive urban points”, it is important to proceed to an in-depth analysis of numerous social, cultural and spatial factors and their synergies (de sola morales, 2008). thus, the selection of urban spots for intervention is not random nor optheoretical context journal of sustainable architecture and civil engineering 2022/1/30 8 portunistic; it is the product of a profound analysis. this fact differentiates the urban acupuncture method from other types of small-scale interventions in the realm of tactical urbanism. in this respect, the terms urban acupuncture and tactical urbanism are not synonyms; they both however employ a similar range of practices. urban acupuncture has the intention to provide a more responsive urban environment for all social groups. claiming the “right to the city” as described in the work of henri lefebvre, urban acupuncture indicates the importance of re-programming the public space so as to serve a greater purpose; the achievement of a sustainable urban environment. most of the projects exercise a high degree of reversibility leaving room for corrective measures compared to large-scale urban interventions. explorations in micro-scale urbanism include also impromptu bottom-up initiatives that express localized needs, introducing participatory urban spaces. this approach reveals the transformative power of citizen-led action. focusing on the “citizens’ perspective”, small scale interventions highlight the unexploited opportunities of the bottom-up initiatives. contemporary findings on urban dynamics instigate the ever-growing interest on interventions in the small scale of the city. as stated in pertinent literature “cities need big plans and small tactics, so as to raise public awareness and interest (lyndon and garcia, 2015). this thesis reveals a differentiation between strategies (from a top-down strategic planning standpoint) and tactics. strategies refer to a kind of master-planning key-policy while tactics serve the ever-changing citizens’ needs. nonetheless, tactics and strategies are of equal value and could be used as complimentary tools for urban renewal. furthermore, a combination of small-scale methods could also benefit areas like the selected case study where there is an evident lack of urban infrastructure. using urban acupuncture as a compass to navigate within the complex ex-refugee urban fabric, the emphasis on urban infrastructure upgrade could undoubtedly benefit the area of study. form this point of view, tactical urbanism comprises a range of planning and design strategies so as to improve inefficient urban infrastructure by employing low-cost, usually small-size, often temporarily or non-spatial means. (balicka et.al, 2021). it is also referred as “guerrilla urbanism”, “pop-up urbanism”, “city repair” or “diy (do-it-yourself) urbanism”. the term was introduced after translating michel certeau’s book the practice of everyday life in 1984, where he used the term in order to distinguish the scale of the mentioned practices compared to “strategic urbanism”. the term was broadly popularized though, by m.lyndon and t.garcia in 2015 through their book tactical urbanism: short-term action for long-term change. the initial rise of tactical urbanism in north america was underpinned by citizens’ return to the urban centers combined with financial factors associated with the great recession of 2007. the necessity for fast, low-cost and high-impact urban improvements was introduced in a globalized context of perpetually strained resources in the aftermath of the urban sprawl. this turn to small scale interventions was also corroborated by landscape architects and artists. according to literature, art installations of the 70s provided commentary on allocation and use of public space (lydon and garcia, 2015). from this point of view the work of bonnie ore sherk was a representative example. the series of art installations in san francisco was an inspiration for the improvement of urban infrastructures (ibid). in 2010, the activities of the new urbanist “cnu nextgen” group, supported the further application of the method through recommendations for the city of new orleans so as to deal with the damages of the hurricane katrina (balicka et.al, 2021). since 2010, tactical urbanism has been an emerging trend in many cities all over the globe (angelidou, 2019). to be more specific, the method was used in christchurch in new zealand following an earthquake and in france at paris plages, a famous long term tactical urbanism intervention. the reasons for its success may be associated with the level of complexity met in contemporary urban surroundings, where a linear, top-down approach does not fulfill citizens’ needs (balicka, et.al., 2021). considering the competing views and the diverse demands of different stakeholders, decision making might be a rather intricate and long process. thus, small scale experimental 9 journal of sustainable architecture and civil engineering 2022/1/30 approaches could better facilitate the purpose of improving the urban environment. despite their slight differences, both urban acupuncture and tactical urbanism reinforce social and spatial cohesion, avoiding the dichotomy of upscale and degraded urban enclaves. based on literature, increasing socio-spatial inequalities challenge social cohesion in urban europe (cassiers, and kesteloot, 2012). to analyze present-day societal and spatial dynamics, one should reckon the fact that european cities display a variety of socio-spatial structures. as for the wider area of athens, the capital of greece, vertical segregation (maloutas, 2007) and spatial patterns depended on historical and socio-political parameters, create a specialized urban context. to be more specific, the phenomenon of vertical segregation involves socio-economic discrepancies among the tenants of the same building, with the lower socio-economic strata occupying the lower floors. from this point of view, the social role of open public spaces is increased so as to offer a homogenous urban experience to all citizens. focusing on the case of greek metropolitan areas, the refugee rehabilitation of the interwar period (1930s) shaped the urban fabric in such a way that large scale interventions could be perceived as synonyms to large scale demolitions. high building density in nikea (fig.2), does not allow large scale interventions, reaching at least 9.436,14 citizens per km2. thus, nikea is one of the most populated municipalities in the attica region (report inemy, 2015). today, the presence of vulnerable households in the old refugee houses (low income, low educational level and immigrants) requires socially and culturally sensitive localized gestures so as to avoid severe gentrification in the area (tousi, 2014 and 2019). in this urban context, mobilization of capital, resources and administrative services at different scales is necessary so as to forge new institutional arrangements. according to the greek urfig. 2 aerial view taken in 1953, the selected case study, the post-refugee area of nikea, source: technical services of the municipality of nikea, archival material ban planning legislation, the value of open public spaces was adequately acknowledged during the 1980s with the law 1337/1983 and the presidential decree 23.02.1987 (papageorgiou and gemenetzi, 2017). since then, effort has been made so as to protect urban and peri-urban green. furthermore, unexploited urban empty spaces are at the forefront the last couple of years so as to reinforce socio-spatial cohesion in greek metropolitan areas. on account of all these, this paper explores the potentialities and challenges of the implementation of urban acupuncture in dense greek urban complexes, as in the case of the ex-refugee neighborhoods, taking into consideration the international experience in the field and the special circumstances in the area of study. this special urban context refers also to the unique character of the existing open public spaces. according to the masterplan of the area, they are officially declared public spaces , however they feel like private because of the way the citizens use them. these spaces include the communal spaces inside each city block as well as the pedestrian corridors that connect one city block to another. since the first establishment of the refugee settlement, the residents use these intermediate spaces for a variety of household activities (e.g., laundry, hirschon 2004 and tousi, 2014). they also place tables and chairs in the communal spaces and between buildings so as to organize afternoon gatherings, offering a sense of social solidarity at neighborhood level (tousi, 2014 and 2019). journal of sustainable architecture and civil engineering 2022/1/30 10 as de sola morales (2008) puts emphasis on the spaces between the buildings and the activities of citizens, it is of great interest to look in depth the selected case study so as to explore the potential of applying urban acupuncture and tactical urbanism methods. moreover, the great number of scattered open spaces in the area combined with their unique social and cultural character could serve as a motive for creating a network of synergic open spaces in the area. this network could improve the living conditions in the area as well as the microclimate conditions taking in terms of both socio-cultural and environmental factors. to combat the ramifications of the economic crisis of 2008, forms of tactical urbanism could provide viable solutions in the area of study, including the local community in the decision-making process. a brief overview of the socio-spatial specificities of the ex-refugee urban quarters according to literature, the urban growth met in european mediterranean cities, is described as a hybrid urban model, something between compact cities and excessive sprawl (kiousopoulos and tousi, 2017). attica metropolitan region follows a multi-core urban development, with many different centers of various importance and influence. major demographic flows during the 20th century have strongly affected the physiognomy of metropolitan attica region, where the selected case study belongs. these flows determined the urban geometry and morphology as well as the social synthesis of the greek urban areas. thus, contemporary environmental and social challenges are strongly connected to the demographic flows and the policies implemented afterwards. the first important demographic flow was the refugee population as a consequence of the asia minor catastrophe in 1922. more than 1.500.000 refugees found shelter in greece, 48% of whom resided in the wider area of the urban conglomeration of athens-piraeus (pentzopoulos,1962). in spite of their gradual urban assimilation¹, they suffer today from various problems owed largely to their first foundation and the polices followed afterwards. furthermore, alterations in urban planning legislation during the 60s and 70s allowed the construction of higher building volumes, deteriorating the microclimatic conditions of the existing urban centers and the refugee areas. higher population density, overlapping shadows among buildings, insufficient sunlight, poor natural ventilation are only a few of the problems affecting the quality of life in the ex-refugee urban areas. these urban problems combined with air pollution, photochemical smog and airborne particulates led to the extensive suburbanization of attica region after the 1990s. this suburbanization process affected the refugee areas as well; a significant portion of the population abandoned the old refugee apartments (see pictures 3 and 4). simultaneous to this middle-class outflow (maloutas et.al, 2001), was the inflow of economic immigrants after the 1990s, mostly from balkan countries and the former ussr. after 2005, immigrants from asian countries are observed in the ex-refugee urban neighborhoods because of the low rents (tousi, 2014). they mostly reside in degraded refugee housing complexes characterized by poor facilities (e.g., lack of central heating, see pictures 3 and 4). on account of these conditions, one of the crucial issues is the decay of the old refugee housing complexes that today host fig. 3 rental apartments in nikea, contemporary condition, authors’ field work, 2014 1 the refugee housing enclaves were founded 1 to 4 kilometers outside the boundaries of the existing urban structures, usually near industrial units (sarigiannis, 2000). this planning choice was associated with social exclusion and segregation according to pertinent sources (leontidou, 2017). 11 journal of sustainable architecture and civil engineering 2022/1/30 fig. 4 abandoned refugee housing complexes, contemporary condition, authors’ field work, 2014 vulnerable households – mostly immigrants and low-income elderly people (tousi, 2014). this situation is challenging social cohesion, leading neighbourhoods to urban blight. moreover, high population density, inefficient open spaces, poor thermal comfort, energy poverty and lack of holistic planning are some other noteworthy issues. however, despite this unfortunate condition, there are some potentialities, such as the presence of scattered open spaces of different scales, that could be regenerated in terms of urban acupuncture to reinforce urban compactness. the role of open spaces in nikea. sensitive urban points for further consideration the urban history of the area of nikea is strongly associated with the asia minor catastrophe in 1922. before the refugee rehabilitation, the area had not been an organized urban suburb (hirschon, 1989). one important factor that still affects the physiognomy of the area is the presence of a communal open space inside each city block. this open intermediate space was the borderline between private and public, a multi-functional semi-private, semi-public space that fostered social networks at neighborhood level. after the first refugee settlement, social networks at the neighborhood level served as a shield against social exclusion (hirschon, 1989). from this point of view, the presence of communal open space in the middle of each city block was rather significant. it offered a suitable field for social exchange and interaction. thus, apart from their environmental value, these spaces have a special sentimental and symbolic value in terms of urban collective memory. nonetheless, through the lapse of time, changes in the urban fabric have transformed the existence and quality of these open spaces. in some cases, the demolition of the old refugee housing complexes, the distribution of properties to the refugee descendants, and the construction of new multi-storey blocks of flats have led to the extinction of the intermediate communal space. despite these alterations, the area preserves today a significant number of open spaces, as presented in table 5 and in fig.6. the intermediate open spaces as well as the pedestrian alleys could be perceived as sensitive urban points in terms of urban acupuncture. as presented in table 5, categories a, b, and c comprise variations of the intermediate communal space inside the city blocks, while categories d and e, include open spaces outside the blocks, mostly squares and parks. in particular, there are only four spaces of more than 500m2 in the vicinity. categories a, b, c refer to enclaves inside the initial refugee urban core, counting 41 open spaces. the first three categoresults and discussion table 5 categorization of available open spaces in the area of study, authors work category coding number of spaces available area prevailing neighboring land uses presence of old refugee houses a 12 less than 40 m2 mostly residential yes b 20 40 m2 to 90 m2 mostly residential yes c 9 90 m 2 to 100 m2 mostly residential rare d 25 100 m2 to 500 m2 residential/commercial no e 4 more than 500 m2 residential/educational no journal of sustainable architecture and civil engineering 2022/1/30 12 ries are strongly associated with the derelict refugee housing complexes, as presented in table 5. apart from their significant number, another advantage is the fact that they are easily accessible since they are found in the middle of each city block. as for the surrounding land uses, they are mostly residential with some exceptions of commercial and educational uses, near the larger open spaces (categories d and e). the existing narrow corridors between the old refugee houses (see fig.6) could be transformed into green corridors with suitable design solutions. nonetheless, this is something fig. 6 sensitive urban points in the area of study according to field work, authors’ work map 7 different scales of open spaces in the municipality of nikea, undergraduate thesis, antonia perouli, 2020, university of west attica, school of interior architecture that the citizens have already tried to implement using their own means and aesthetics as presented in pictures 9 and 10. from this point of view, all these scattered open spaces could become a sustainable green network able to improve microclimate conditions, with greenways and green corridors to complete the patchwork of small and large green open spaces in the area. in particular, the small open spaces could function as pocket parks, redesigned in terms of urban acupuncture. according to literature, even the small urban voids could be exploited in creative ways so as to foster socio-spatial cohesion and improve thermal comfort. following key-design parameters as indicated in international literature (sinou, 2013) these small open 13 journal of sustainable architecture and civil engineering 2022/1/30 table 8 table presenting the keyparameters for successful design of small-scale public spaces, (according to sinou 2013) fig. 9, 10 communal public corridors inside the city blocks, vegetation and residents’ decorative elements, authors’ field work, 2020 spaces have the potentiality to transform the general physiognomy of the area, improving also microclimatic conditions. these key parameters could be summarized in the table 8 (according to sinou, 2013). unfortunately, despite potentialities, there are certain challenges. as illustrated in the pictures 11 and 12, these intermediate open spaces have inefficient design, being used as auxiliary spaces outside the houses. there are also illegal ground floor constructions that occupy communal public space as illustrated in map 11 and figures 11,12. the only official approach related to urban regeneration dates back to the 1990s. however, this regeneration process did not meet citizens’ needs. it focused on redesigning the intermediate spaces in the city blocks by placing concrete jardinières without taking into account users’ activities. these flower-boxes where not accompanied by benches or other infrastructure that could support the formation of a focal-meeting point (see sinou, 2013) and thus the citizens continued to bring their own chairs for their evening gatherings even after the completion of the regeneration project. the way in which plants were placed did not key categories key parameters space _ surfaces _ focal point _ space identity _ size environment _ location and linkage _ environmental performance (adjustment to local climate conditions) society _ users _ accessibility _ amenities/activities _ safety/maintenance journal of sustainable architecture and civil engineering 2022/1/30 14 fig. 11, 12 typical examples of illegal ground floor construction (in front of the refugee housing complex) on the intermediate communal space of the city block, nikea, tousi, 2019 take into consideration the flows and gatherings of locals either residents or passers-by. this topdown approach could not be described as efficient considering the special networks expanded on the intermediate public spaces of the area. the pedestrian routes created during this regeneration project have been since occupied as unofficial parking areas. (fig. 14, 15). thus, another important issue affecting the quality of existing open spaces is the lack of parking spots in the area. as a result, parts of the existing open spaces are used for parking (see picture 14). as observed during fieldwork, the post-refugee urban core suffers from urban blight without being included in strategic planning. especially during the economic crisis of 2008, no funds were allocated for the regeneration of the area. given the location of a new metro station in the area, there are concerns for the future of the degraded enclaves. the increasing interest from private investors raises skepticism on the potential type of future development of the area. if we combine this with the fact that most of the refugee descendants rent the old refugee houses to vulnerable households, then the risk of gentrification could be a possible future scenario. to resist market driven solutions, it important to organize grassroot efforts to improve the urban environment with effective citizens-led, low-cost interventions. the multiple owners of each refugee apartment fig. 13 illegal ground floor constructions in the intermediate space of each city block, inside the circle is the location of the new metro station that is a part of the blue metro line which connects piraeus port to the national airport eftherios venizelos, authors’ field work 2021 15 journal of sustainable architecture and civil engineering 2022/1/30 (refugee descendants) could be perceived as another barrier to overcome. from this point of view, strong community driven initiatives should motivate the owners of the refugee houses to participate in the procedure with the view to preserve the identity of the area. the rapid upgrading of the area around the new metro station would induce further gentrification procedures within the ex-refugee urban core (see fig.13). general guidelines for further application and research. obstacles, advantages and recommendations the results of this research involve key obstacles and key advantages as well as potential recommendations for the future development of the area. the analysis of the former is presented in three subject areas following the three pillars of sustainability: environmental/spatial, social/ cultural and economic (see table 16). all recommendations have taken into consideration the specificities of time and space as presented in the previous chapters so as to propose viable solutions for the selected case study. these recommendations might focus on forms of tactical urbanism and urban acupuncture as well as officialy planned proposals. a combination of bottom-up and top-down approaches in the area may benefit the efficient regeneration of the degenerated urban ex-refugee core. the problem of the decaying refugee housing reserve is so severe that official actions should be taken (issues of maintainance and responsibility sharing). from this point of view, a mixture of planning methods could help the amelioration of this intricate situation. to be more specific, state authorities should delve into the case of nikea so as to reach a decision on which refugee houses could be preserved. then it is important to understand residents’ perspectives on the future development of the area, to bridge the gap between adminisrtative authorities/experts and residents. the following table presents the identification of obstacles and advantages of the area that could be either used in top-down or bottom-up planning procedures. the below mentioned positive and negative attributes could be used to detect the “sensitive urban points” as mentioned in relevant urban acupuncture literature (see theoretical framework) and to set a solid framework to prioritize the necessary actions for the improvement of the quality of life in the area. table 16 illustrates key-obstacles and key-advantages in the area while table 17 presents recommendations to overcome the obstacles. according to the analysis of the area, all intermediate city block spaces could be perceived as “sensitive urban points” in terms of urban acupuncture. to activate these spaces a set of actions should be taken to successfully surpass the key-obstacles mentioned above. moreover, a combination of bottom-up and top-down approaches could benefit the inclusive planning of the area so as to eliminate the risk of gentrification. fig. 14, 15 the urban regeneration of the 1990s, concrete jardinières, pedestrian routes occupied as parking spots, author’s field work 2020 journal of sustainable architecture and civil engineering 2022/1/30 16 table 16 key-obstacles for activating the sensitive urban points of the area and advantages of the existing urban environment regarding the future development of the area, authors work table 17 recommendations to overcome key-obstacles, authors work main categories key obstacles for activating the “sensitive urban spots” key advantages identified environmental / spatial illegal extensions occupying communal areas open space availability decaying building stock different space scales former non effective regeneration in the ‘90s, lack of “focal point” see sinou,2013 proximity to large green areas lack of parking spots leads to cars occupying communal areas existing spontaneous indigenous vegetation overlapping shadows among buildings poor natural ventilation in some cases because of the irregular placement of the illegal extensions fragmented pedestrian routes low levels of noise and air pollution social / cultural unclear distinction between public/private, residents placing private objects on the communal space there is a warm atmosphere in communal open spaces owed to the local social networks presence of vulnerable households that are at risk of exclusion. fear of severe gentrification after urban regeneration strong sense of community & interaction sense of neighborhood, solidarity networks economic lack of funding proximity to new metro stations identification of buildings with demolition possibility low land prices might attract private investors (around 1100 euros/m2 ) complex ownership status proximity to supralocal cultural uses (e.g. katrakeio theater) and athletic facilities recommendations possible method _ reinforcement of accessibility and connectivity of open urban space network _ creation of focal points in each city block according to users’ activities _ explore sustainable mobility (pedestrian, bicycle routes etc.) _ legalize or demolish illegal extensions or annexes to existing houses in order to define the actual size of the open space _ evaluation-thorough study of existing refugee stock in terms of static adequacy. _ enhance existing vegetation _ define parking zones both bottom-up and top-down bottom-up initiative to identify the “focal points” of each city block concerning the existing outdoor activities and pedestrian flows top-downto officially define pedestrian routes and cycling routes top-down top-down bottom-up and top-down top-down _ study in depth the existing social networks so as to offer the necessary infrastructure and urban furniture _ study existing and potential uses _ define the limits between private and public space _ inclusive community committee (representation of all population groups) bottom-up initiative to create a user-friendly intermediate urban space/ urban infrastructure with the help of tactical urbanism bottom-up initiative so as to define uses in the open space of each city block bottom-up initiative to motivate all residents and owners to participate _ state and eu funding opportunities form the municipality or central government _ clarification of the ownership status and the demolition process of the perilous condition buildings some citizens-led actions could motivate local municipal authorities to register for relevant eu’s funding programs bottom up and top-down (cooperation among residents and municipal authorities) 17 journal of sustainable architecture and civil engineering 2022/1/30 it has become clear from the study that the implementation of small interventions in the realm of urban acupuncture is bound to create significant potential in ex-refuge areas. the investigation has shown that in these areas, space availability is limited and the quality of existing space is poor, however social cohesion is strong, deriving from common history and difficulties of the past and present. high building density leads to localized small-scale gestures. the lack of funds in the aftermath of the economic crisis of 2008 could be counterbalanced by forms of tactical urbanism with low-cost interventions. citizen-led initiatives could improve urban infrastructure in the area (urban furniture and vegetation). however, issues relevant to the preservation of the old refugee houses require official support from the state. a combination of bottom-up and top-down strategies and tactics could benefit the area the most. despite the difficulties, several sustainability goals are considered as possible to implement, thereby forming a more holistic strategy that can improve the built and unbuilt environment, as well as citizen’s living conditions in the area. given the pilot character of this study, research methodology might find analogies with other ex-refugee urban areas in greece so as to activate their “sensitive urban points” in terms of urban acupuncture. acknowledgements the authors would like to thank the us fulbright student research grantee to greece, ms abigail chernila, for editing the manuscript. references agathangelidis i., cartalis c., santamouris m., urban morphological controls on surface thermal dynamics: a comparative assessment of major european cities with a focus on athens, greece. climate. 10.3390/cli8110131, 2020, available at https://www. researchgate.net/publication/345898495_urban_ morphological_controls_on_surface_thermal_dynamics_a_comparative_assessment_of_major_european_cities_with_a_focus_on_athens_greece https://doi.org/10.3390/cli8110131 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https://www.researchgate.net/publication/320012015_spatial_environmental_planning_ in_athens_and_thessaloniki pentzopoulos d., the balkan exchange of minorities and its impact upon greece. mouton and co, the hague, 1962. https://doi.org/10.1515/9783112415863 rontos, k. mavroudis, c. georgiadis, t., suburbanization: a post world war ii phenomenon in the athens metropolitan area, greece, 2006, available at https:// www.researchgate.net/publication/23732333_suburabout the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). tousi evgenia dr.architect-urban and regional planner, adjunct lecturer university of west attica, school of applied arts and culture, department of interior architecture main research area sustainable architecture, urban and regional planning adress e-mail: etousi@uniwa.gr maro sinou dr. architect-professor university of west attica, school of applied arts and culture, department of interior architecture main research area sustainable architecture, urban planning and design adress e-mail: msinou@uniwa.gr antonia perouli interior designer, graduate student university of west attica, school of applied arts and culture, department of interior architecture main research area sustainability in urban design and interior space adress e-mail: antoniaperouli@gmail.com banization_a_post_world_war_ii_phenomenon_in_ the_athens_metropolitan_area_greece santamouris m., ban-weiss g., osmond, p., paolini, r., synnefa a., cartalis c., muscio a., zinzi m., morakinyo t., ng e., tan z., takebayashi, h., sailor d., crank, p., taha, h. pisello, a.l., rossi f., zhang j., kolokotsa d., progress in urban greenery mitigation science assessment methodologies advanced technologies and impact on cities, journal of civil engineering and management., 2018, 24. 638-671. https://doi. org/10.3846/jcem.2018.6604 sarigiannis g.m., athens 1830-2000, athens, symmetria publications, 2000 sinou, m., parameters contributing to the design of a successful urban pocket park, 2013 available at https:// www.researchgate.net/publication/260862210_parameters_contributing_to_the_design_of_a_successful_urban_pocket_park tousi e., how socio-spatial transformations affect the use of public space. a case study from the greek urban reality“. design principles and practices: an international journal, common ground publishing, university of illinois research park, volume 6, 2013, issn 2325-1328.https://doi.org/10.18848/2325-1328/cgp/ v06i03/38505 tousi e. (2014) ο αστικός χώρος ως πεδίο μετασχηματισμών υπό το πρίσμα του προσφυγικού ζητήματος. η περίπτωση της ευρύτερης περιοχής αθήνας-πειραιά [urban socio-spatial transformations in the light of the refugee issue. the case of the urban agglomeration of athens-piraeus]. phd thesis, national technical university of athens, school of architecture, sector of urban and regional planning, available at https://thesis.ekt.gr/thesisbookreader/ id/42796#page/1/mode/2up (in greek) 83 journal of sustainable architecture and civil engineering 2021/2/29 *corresponding author: mahdavinejad@modares.ac.ir past and future trends on the effects of occupant behaviour on building energy consumption received 2021/03/01 accepted after revision 2021/08/04 journal of sustainable architecture and civil engineering vol. 2 / no. 29 / 2021 pp. 83-101 doi 10.5755/j01.sace.29.2.28576 past and future trends on the effects of occupant behaviour on building energy consumption jsace 2/29 http://dx.doi.org/10.5755/j01.sace.29.2.28576 mahsa torabi, mohammadjavad mahdavinejad* high-performance architecture laboratory, department of architecture, tarbiat modares university, tehran, iran introduction in recent decades, the need for an accurate evaluation of energy use in buildings has become increasingly growing due to the rise in environmental awareness and political pressure around the world. the estimation of energy consumption is, therefore, a crucial criterion during building early-stage design. this paper investigates the recent trends and achievements in modelling occupant behaviour in energy simulation studies and aims to highlight achievements and research gaps in the domain. this study presents a state-of-the-art theoretical review of the research background through published papers in leading journals within this research domain. the main goals of this study lay in the two layers of determining recent research trends and crucial findings in the subject of occupants’ behaviour and energy consumption, and more importantly, to identify research gaps for future studies. this research review highlights several areas for future research including studying behaviour in different countries considering various climate, cultures and comfort preferences affecting energy-driven behaviour and conducting similar studies in different building typologies and occupancies. moreover, based on the reviewed article, it is clear that evaluating occupant behaviour as an independent variable on a larger scale energy analysis in urban studies needs to be addressed in future studies. the authors found a lack of comprehensive approaches to comfort and considering all forms of comfort while studying behaviour and consumption in recent studies. it is recommended that further investigation of behaviour and total energy consumption regarding occupant real comfort conditions be conducted. keywords: building energy consumption, occupant behaviour, thermal comfort, energy efficient architecture, consumption prediction. the building sector is the largest energy-consuming sector, accounting for 40% of the final energy consumption globally and an equally important source of carbon emissions. it also declares in less developed regions, energy use in buildings represents as much as 80% of the total energy use (delzendeh, wu, lee, & zhou, 2017). thus, predicting energy consumption is becoming more important in the design and construction of buildings, from the early design stages to the post-occupancy and demolish phase in building life cycle (bemanian & torabi, 2019). energy consumption in buildings is related to various factors including construction details, material specifications, climate, location, passive and active design strategies, the quality of the installed hvac (heating, ventilation, and air condition) system, maintenance, and occupant’s interaction with the building (becchio, bello, corgnati, & ingaramo, 2016; song, zhou, zhang, zheng, & yan, 2017). the relation journal of sustainable architecture and civil engineering 2021/2/29 84 and interaction of these elements in a building are morphed in the early stages of design, which implicate the importance of evaluation and assessment in this phase. the utilization of simulation tools and running energy consumption studies in the design process help architects estimate the energy demand of the initial design and give them the chance to alter the design in order to enhance efficiency. therefore, the accuracy of the energy simulation study is of great importance because not only it can change the architectural design output but also it can guide the whole design toward fulfilling sustainable and environmental-driven aims. although the current trend of building design has benefited a lot from energy calculating assistant tools, several studies in recent years showed that there is a remarkable difference between the predicted and actual energy consumption of buildings which needs more investigation (kim et al., 2017; ouf, issa, & merkel, 2016; pellegrino, simonetti, & chiesa, 2016; virote & neves-silva, 2012). cali et al. reported that the actual consumption amount is sometimes up to 3 times greater than the estimated amount in design (z. yu, li, li, han, & zhang, 2015). the result of a similar study by norfor et al. represents a more than 50% increase in actual energy consumption. in their study, researchers measured the actual annual energy consumption of a three-story office building located in newjersey. the annual consumption was 325 kwh/m2, which is over twice the predicted value of 125 kwh/m2. researchers introduced several reasons as a cause of this gap, for instance, this performance gap can be due to the difference between the building design and the as-built or this might be the result of equipment and material specifications (norford, socolow, hsieh, & spadaro, 1994). besides the mentioned factors, another influential factor in real energy consumption is building occupants by the means of their presence and thermal behaviour which forms their interactions with the buildings. occupant interaction with the building can vary a lot including opening windows and blinds, use of hvac systems, changes in setpoints due to thermal preference, maintenance and equipment efficiency, use of equipment and lightings, using hot water, etc (delzendeh et al., 2017; gilani, brien, gilani, & brien, 2017). occupants and their thermal behaviour are taken into account in simulation studies but recent studies have revealed that this factor has a great direct influence on total consumption and is more complex and dynamic than was assumed till now (becchio et al., 2016; kim et al., 2017; leroy & yannou, 2018). nevertheless, real-time energy use evaluation has been studied in numerous research projects. for example, in a study by yun et al. on two identical flats within the same building block, the analysis demonstrated a significant difference between the total energy consumption. researchers introduced differences in occupancy levels and duration and variations in the occupants’ thermal preferences as the key reasons for different total energy use which highlights the pivotal role of occupants in energy consumption and building environmental footprint (yun, choi, & kim, 2014). a study on the energy consumption of six commercial buildings in south africa (with hot and dry climates) reported that 56% of the actual energy consumption was consumed during nonworking hours, which in simulation studies was not considered. to be more detailed, the reason for this remarkable gap is that occupant behaviour was not modeled in primary energy studies based on reality. in this case, researchers determined that occupants failed to turn off the hvac system and lights before vacating the building, which results in doubling the total consumption (alam, bao, zou, & sanjayan, 2017). in another study, martinaitis and zavadskas conducted five different studies to evaluate the efficiency of the current simulation tool, even with accurate models. researchers concluded that human behaviour and occupant preferences were the main two reasons for the observed gap between prediction and real-time energy consumption (s. wang, kim, & johnson, 2017). despite active research being undertaken in this area, the findings are still sparse and fragmented and, therefore, there is a real need for international collaboration in the sharing of collected data and discovered findings. this paper aims to conduct a comprehensive review of existing studies 85 journal of sustainable architecture and civil engineering 2021/2/29 in a specific domain, to discover the effectiveness of occupant behaviour on energy consumption and environmental footprint in residential buildings. this study aims to identify the latest research trends, point out major findings achieved and facilitate future works and projects to fill the gaps in the edge of knowledge. sampling review papers usually start with a process of ‘search’ for relevant articles, using citation indexes against predetermined criteria for eligibility to provide a list of papers relating to the research area. to reduce bias, a clear approach for research was adopted, including both quantitative and qualitative analysis as well as reviews and technical notes. therefore, science direct as the leading citation index organization was used. for this study, the terms “building energy” and “occupant” were used to select any paper where it was found in the title, abstract, and or keywords. to limit this wide scope with more than a thousand papers and to focus closely on the influence of behaviour on building energy consumption, another search was made through the database using more relevant keywords. as a result, both “occupant behaviour” and “energy consumption” have been repeatedly used in the title and keywords. following this selection process, a search up to 2019 identified more than 44 research papers for this review. publication date material and method fig. 1 number of related papers by publication date 4 113 fig. 1. number of related papers by publication date 114 2.2.2. leading countries in the field: 115 fig. 2 demonstrates the scheme of the most active countries in this field. the radius of the circle shows 116 the number of published papers while the colour indicates gdp (gross domestic product) in 2020_as 117 one of the criteria for economic developments of the country. the data used in this section is based on 118 the affiliation of the corresponding author who is responsible for the project and academic contacts 119 about the research. 120 based on reviewed papers in this study, the united states and the republic of china are the leading 121 countries in this field, followed by respectively republic of korea, canada and netherlands, along 122 with the uk, with the most published papers in this field in the studied period. european researchers 123 are also active in this research area in contrast to researchers from developing countries in central 124 asia, the middle east, and also africa with no studies on the list. it can be concluded from the data 125 that the most active countries in the field, are also among the countries with the world's highest 126 economic level while less active countries are mainly from developing economies. the exceptions are 127 recently growing economies (such as brazil, india and saudi arabia) with high gdp and limited or 128 no contribution to the research. it is anticipated to have researchers from these countries to investigate 129 occupant's behavioural impact or pattern on their building sector in following years. 130 131 132 1 2 4 4 5 5 4 6 6 7 0 2 4 6 8 1994 1997 2011 2012 2014 2015 2016 2017 2018 2019 n um be r o f p ap er s year publication date the selected papers for review were published between 1994 till 2019 with ascending trends. the majority of papers were published between 2011 and 2020, although early examples of such studies were published in the 1990s. the ascending trend in publication through the 1990s and 2010s is observed in fig. 1; however, the number of publications falls around the 2000s. to fill that gap, the authors added a qualitative research method to find hot topics for this gap time and to validate the findings of the review study. this was conducted using the opinion of experts and researchers of energy conservation, which will be thoroughly discussed in the following “discussion” sections. leading countries in the field fig. 2 demonstrates the scheme of the most active countries in this field. the radius of the circle shows the number of published papers while the colour indicates gdp (gross domestic product) in 2020_as one of the criteria for economic developments of the country. the data used in this section is based on the affiliation of the corresponding author who is responsible for the project and academic contacts about the research. based on reviewed papers in this study, the united states and the republic of china are the leading countries in this field, followed by respectively republic of korea, canada and netherlands, along with the uk, with the most published papers in this field in the studied period. european researchers are also active in this research area in contrast to researchers from developing countries in central asia, the middle east, and also africa with no studies on the list. it can be concluded from the data that the most active countries in the field, are also among the countries with the world’s highest economic level while less active countries are mainly from developing economies. the exceptions are recently growing economies (such as brazil, india and saudi arabia) with high gdp and limited or no contribution to the research. it is anticipated to have researchers from these countries to investigate occupant’s behavioural impact or pattern on their building sector in following years. journal of sustainable architecture and civil engineering 2021/2/29 86 while fig. 2 shows the leading countries in this field of research, fig. 3 shows the distribution of nations whose thermal behaviour has been studied. these pictures show some similarities and analogies. a similar pattern in both pictures shows that researchers are more inclined to research their own countries, such as usa, canada, china and european union. this is rational since most of the papers are derived from funded projects aiming to qualify the impact of the study on their stakeholders. the graph also shows that the academic community has neglected some parts of the world, as a result, a vast region is observed with almost no research to address occupants’ energy-driven behaviour. fig. 3 frequency and geographical distribution of investigated cases 5 fig 2geographic distribution of active countries 133 while fig. 2 shows the leading countries in this field of research, fig. 3 shows the distribution of 134 nations whose thermal behaviour has been studied. these pictures show some similarities and 135 analogies. a similar pattern in both pictures shows that researchers are more inclined to research their 136 own countries, such as usa, canada, china and european union. this is rational since most of the 137 papers are derived from funded projects aiming to qualify the impact of the study on their stakeholders. 138 the graph also shows that the academic community has neglected some parts of the world, as a result, 139 a vast region is observed with almost no research to address occupants' energy-driven behaviour. 140 the geographical distribution of published papers shows the necessity of conducting similar researches 141 in less regarded regions that have consumed more than 25% of total global primary consumption in 142 2017. this region includes africa, central asia, the middle east, and south america (feng, yan, & 143 wang, 2016). 144 it is important to bear in mind that occupant behaviour is a dependent variable that is known to be 145 affected by cultural, geographical and climatic variables; therefore, to study the effect of this variable 146 on energy consumption, researchers should consider the influence of location and culture and aim to 147 conduct occupant behaviour studies locally. 148 149 fig. 3. frequency and geographical distribution of investigated cases 150 another noteworthy point derived from fig. 2 and fig. 3 is that pioneer countries in this area have 151 followed two opposite trends. some of them like the united states and canada have published one of 152 the first papers in this area in the 1990s and continued working on this subject in the following years 153 till now. in analogy, another pioneer country, japan, directed the research flow toward other realms. 154 in the next years, other papers also studied japanese occupants and their thermal behaviour by non-155 japanese researchers. this suggests a good method and sets a good example for less developed 156 countries in this field to collaborate with researchers from other countries to study the energy-driven 157 behaviour of their nation to fill the knowledge gap in the research literature and improve management 158 in energy-consuming sectors. 159 fig. 2 geographic distribution of active countries 4 113 fig. 1. number of related papers by publication date 114 2.2.2. leading countries in the field: 115 fig. 2 demonstrates the scheme of the most active countries in this field. the radius of the circle shows 116 the number of published papers while the colour indicates gdp (gross domestic product) in 2020_as 117 one of the criteria for economic developments of the country. the data used in this section is based on 118 the affiliation of the corresponding author who is responsible for the project and academic contacts 119 about the research. 120 based on reviewed papers in this study, the united states and the republic of china are the leading 121 countries in this field, followed by respectively republic of korea, canada and netherlands, along 122 with the uk, with the most published papers in this field in the studied period. european researchers 123 are also active in this research area in contrast to researchers from developing countries in central 124 asia, the middle east, and also africa with no studies on the list. it can be concluded from the data 125 that the most active countries in the field, are also among the countries with the world's highest 126 economic level while less active countries are mainly from developing economies. the exceptions are 127 recently growing economies (such as brazil, india and saudi arabia) with high gdp and limited or 128 no contribution to the research. it is anticipated to have researchers from these countries to investigate 129 occupant's behavioural impact or pattern on their building sector in following years. 130 131 132 1 2 4 4 5 5 4 6 6 7 0 2 4 6 8 1994 1997 2011 2012 2014 2015 2016 2017 2018 2019 n um be r o f p ap er s year publication date the geographical distribution of published papers shows the necessity of conducting similar researches in less regarded regions that have consumed more than 25% of total global primary consumption in 2017. this region includes africa, central asia, the middle east, and south america (feng, yan, & wang, 2016). 87 journal of sustainable architecture and civil engineering 2021/2/29 it is important to bear in mind that occupant behaviour is a dependent variable that is known to be affected by cultural, geographical and climatic variables; therefore, to study the effect of this variable on energy consumption, researchers should consider the influence of location and culture and aim to conduct occupant behaviour studies locally. another noteworthy point derived from fig. 2 and fig. 3 is that pioneer countries in this area have followed two opposite trends. some of them like the united states and canada have published one of the first papers in this area in the 1990s and continued working on this subject in the following years till now. in analogy, another pioneer country, japan, directed the research flow toward other realms. in the next years, other papers also studied japanese occupants and their thermal behaviour by non-japanese researchers. this suggests a good method and sets a good example for less developed countries in this field to collaborate with researchers from other countries to study the energy-driven behaviour of their nation to fill the knowledge gap in the research literature and improve management in energy-consuming sectors. building type fig. 4 demonstrates the type and typology of studied cases in the reviewed papers. as shown in the graph, the majority of researches in this field have focused on the occupants of residential buildings. that is because of the longer occupancy period and variation in the energy behaviours of occupants. the role of occupants in energy consumption is less-regarded in commercial and educational buildings. energy specialists tend to investigate the energy consumption affected by behaviour mainly in residential buildings (paper, 2017). studying occupant-driven energy loads in public types of buildings will have a significant impact on future building design because individual occupants do not have full control of a building’s hvac and lighting systems in these buildings. this can enhance the potential for other forms of interaction with the building to provide comfort conditions (delzendeh et al., 2017; martinaitis & zavadskas, 2015). as a result, a wider range of variety in occupant behaviour in schools and offices is anticipated, which requires further investigation. moreover, based on previous bps (building performance simulation) studies, occupancy default profile may vary a lot from the real behaviour, which makes the simulation results sometimes inaccurate(s. wang et al., 2017). consequently, the need for accurate profiles, with an approach to culture and climate is of great importance. o’brien. gaetani, et al. conducted an international survey of 274 bps users and developers and found that occupancy assumption in current energy simulation does not align with the complex behaviour occupants show in buildings and is much simpler than state-of-the-art findings. they also mentioned that simulation users are aware of deficiencies in occupancy profile assumptions and they are open to utilizing more detailed occupancy profiles in their modelling (brien et al., 2016). fig. 4 studied cases by building type and typology 7 200 fig. 4. studied cases by building type and typology. 201 2.2.4. climate 202 another criterion for categorizing reviewed researches on this subject is based on the climate of the 203 studied cases. fig. 5 demonstrates the number of studied cases categorized by their climate classes 204 based on koppen-geiger climatic classification. 205 the köppen-geiger climate classification divides climates into five classes: 206 a (tropical), b (dry), c (temperate), d (continental), and e (polar). the second letter shows the 207 seasonal precipitation type: f (no dry season), w (winter dry), or s (summer dry). the third letter 208 indicates the warmth of the summer: a (hot summer), b (warm summer), c (cool summer), d (cold 209 summer), h (hot arid) and k (cold arid). in this climatic system, class names show the most remarkable 210 climatic features of regions in form of three-letters codes. 211 as shown in the chart below, among reviewed papers, several studies have chosen cases from the same 212 climate, for example, roughly 40% of investigated cases belong to the climate class of cfa (humid 213 subtropical climates). cfa climate, which normally is seen on eastern coasts of continents covers, parts 214 of europe, the united states and china, brazil, australia, etc. this climate class has temperate weather, 215 without dry seasons with hot summer. it is mostly humid and a steady rate of precipitation is observed 216 among seasons(canan, golasi, falasca, & salata, 2020; chen & chen, 2013; solutions, beck, & 217 rubel, 2006). 218 initially, it might be assumed to be in response to the high population of this area. this is whilst, there 219 are numerous climates with several times more population that have received scant attention such as 220 b (arid), d (continental), some of c (moderate) and a (tropical) (solutions et al., 2006). the lack of 221 researches in the aforementioned climatic regions, which mostly covers developing countries, again 222 highlights the necessity of investigating the effect of occupant behaviour on building energy 223 consumption in these areas. 224 225 226 fig. 5. frequency of studied climates 227 1 2 1 18 7 1 1 2 6 3 5 0 5 10 15 20 aw af bwh cfa cfb csa csb cwa dwa dfa dfb n um be r o f p ap er s climate classification journal of sustainable architecture and civil engineering 2021/2/29 88 in contrast to the majority of papers dealing with occupants and their behaviour in residential and commercial buildings, schaumann et al. considered simulating occupancy patterns at hospital buildings. as defined by the authors, it is expected that conventional occupant modelling and simulation formalisms may not be suitable in process-driven facilities such as hospitals, airports, train stations, and factories. the authors conducted a new multiagent simulation framework to account for the peculiarities in the modelling of occupancy in such process-driven facilities (schaumann, breslav, goldstein, khan, & kalay, 2017). another noteworthy point extracted from the graph is that some specific building typologies are more popular among scientists and others are neglected in reviewed papers. for instance, different typologies of residential buildings are investigated in several studies to answer different research questions, while there was no study evaluating occupant-driven energy load in high-rise commercial buildings. as the graph demonstrates, among the studied papers, low-rise buildings have drawn more attention in contrast to mid-rise or high-rise buildings. this might be due to the higher frequency and lower level of complexity of the low-rise building. the results show that less than 20% of studied cases were selected from high-rise buildings. considering growing attention to high-rise multifunctional buildings in current metropolises, as well as developed construction techniques, it sounds that occupant behaviour in high-rise buildings should be regarded with much interest in the future. climate another criterion for categorizing reviewed researches on this subject is based on the climate of the studied cases. fig. 5 demonstrates the number of studied cases categorized by their climate classes based on koppen-geiger climatic classification. the köppen-geiger climate classification divides climates into five classes: a (tropical), b (dry), c (temperate), d (continental), and e (polar). the second letter shows the seasonal precipitation type: f (no dry season), w (winter dry), or s (summer dry). the third letter indicates the warmth of the summer: a (hot summer), b (warm summer), c (cool summer), d (cold summer), h (hot arid) and k (cold arid). in this climatic system, class names show the most remarkable climatic features of regions in form of three-letters codes. as shown in the chart below, among reviewed papers, several studies have chosen cases from the same climate, for example, roughly 40% of investigated cases belong to the climate class of cfa (humid subtropical climates). cfa climate, which normally is seen on eastern coasts of continents covers, parts of europe, the united states and china, brazil, australia, etc. this climate class has temperate weather, without dry seasons with hot summer. it is mostly humid and a steady rate of precipitation is observed among seasons(canan, golasi, falasca, & salata, 2020; chen & chen, 2013; solutions, beck, & rubel, 2006). fig. 5 frequency of studied climates 7 200 fig. 4. studied cases by building type and typology. 201 2.2.4. climate 202 another criterion for categorizing reviewed researches on this subject is based on the climate of the 203 studied cases. fig. 5 demonstrates the number of studied cases categorized by their climate classes 204 based on koppen-geiger climatic classification. 205 the köppen-geiger climate classification divides climates into five classes: 206 a (tropical), b (dry), c (temperate), d (continental), and e (polar). the second letter shows the 207 seasonal precipitation type: f (no dry season), w (winter dry), or s (summer dry). the third letter 208 indicates the warmth of the summer: a (hot summer), b (warm summer), c (cool summer), d (cold 209 summer), h (hot arid) and k (cold arid). in this climatic system, class names show the most remarkable 210 climatic features of regions in form of three-letters codes. 211 as shown in the chart below, among reviewed papers, several studies have chosen cases from the same 212 climate, for example, roughly 40% of investigated cases belong to the climate class of cfa (humid 213 subtropical climates). cfa climate, which normally is seen on eastern coasts of continents covers, parts 214 of europe, the united states and china, brazil, australia, etc. this climate class has temperate weather, 215 without dry seasons with hot summer. it is mostly humid and a steady rate of precipitation is observed 216 among seasons(canan, golasi, falasca, & salata, 2020; chen & chen, 2013; solutions, beck, & 217 rubel, 2006). 218 initially, it might be assumed to be in response to the high population of this area. this is whilst, there 219 are numerous climates with several times more population that have received scant attention such as 220 b (arid), d (continental), some of c (moderate) and a (tropical) (solutions et al., 2006). the lack of 221 researches in the aforementioned climatic regions, which mostly covers developing countries, again 222 highlights the necessity of investigating the effect of occupant behaviour on building energy 223 consumption in these areas. 224 225 226 fig. 5. frequency of studied climates 227 1 2 1 18 7 1 1 2 6 3 5 0 5 10 15 20 aw af bwh cfa cfb csa csb cwa dwa dfa dfb n um be r o f p ap er s climate classification 89 journal of sustainable architecture and civil engineering 2021/2/29 initially, it might be assumed to be in response to the high population of this area. this is whilst, there are numerous climates with several times more population that have received scant attention such as b (arid), d (continental), some of c (moderate) and a (tropical) (solutions et al., 2006). the lack of researches in the aforementioned climatic regions, which mostly covers developing countries, again highlights the necessity of investigating the effect of occupant behaviour on building energy consumption in these areas. research type in the field of aec (architecture, engineering and construction), the majority of studies deal with energy consumption or other derived parameters, thus it is anticipated that most researches are conducted with quantitative methods. as the graph shows 75% percent of papers, report the result of quantitative researches while only 25% were carried out through qualitative methods. qualitative researches to categorize the reviewed papers based on their research methods, there would be two groups of qualitative and quantitative papers. qualitative researches can be categorized into three classes based on their main objectives and goals as shown in fig. 6. more than half of the qualitative pa fig. 6 research type and major issues 8 228 2.3. research type: 229 in the field of aec (architecture, engineering and construction), the majority of studies deal with 230 energy consumption or other derived parameters, thus it is anticipated that most researches are 231 conducted with quantitative methods. as the graph shows 75% percent of papers, report the result of 232 quantitative researches while only 25% were carried out through qualitative methods. 233 234 2.3.1. qualitative researches: 235 to categorize the reviewed papers based on their research methods, there would be two groups of 236 qualitative and quantitative papers. qualitative researches can be categorized into three classes based 237 on their main objectives and goals as shown in fig. 6. more than half of the qualitative papers are 238 review papers, which investigate, summarize and outline recent trends in this area of research. in 239 undertaking this paper, we focused more on quantitative researches because of their larger number, 240 more notable achievements, and the researcher’s inclination toward them. 241 242 fig. 6. research type and major issues 243 244 2.3.2. quantitative researches: 245 the majority of papers in this area investigate responses to the research question by quantifying the 246 collection and analysis of data. this type of research is further discussed in this section from two 247 perspectives: the main subject and applied methodology. similar to qualitative papers, more than half 248 of the quantitative studies focused on energy consumption (65%). among all quantitative reviewed 249 papers, the most popular subject that has drawn the researcher’s attention is that to what extent and 250 how occupant behaviour can affect energy consumption (becchio et al., 2016; burgas, melendez, & 251 colomer, 2014; deng & chen, 2019; engvall, lampa, levin, wickman, & öfverholm, 2014; leroy 252 & yannou, 2018; norford et al., 1994; park & kim, 2012; peng, rysanek, nagy, & schlüter, 2018; 253 rafsanjani & ahn, 2016; rafsanjani, ahn, & chen, 2018; santin, 2011; song et al., 2017; virote & 254 neves-silva, 2012; z. wang, zhao, lin, zhu, & ouyang, 2015; s. wei, jones, & de wilde, 2014; y. 255 wei et al., 2019; xie, pan, jia, xu, & huang, 2019; zhun yu, fung, haghighat, yoshino, & morofsky, 256 2011; yu zhun jerry, haghighat, fung, morofsky, & yoshino, 2011; yun et al., 2014; yun & kim, 257 2012). many studies focused on a single form of energy consumption (either heating, cooling, 258 electricity, dhw (demanded hot water), etc.) and dismissed the impact of occupants on other types 259 of energy consumption. this is in analogy with the fundamentals of building physics in which building 260 pers are review papers, which investigate, summarize and outline recent trends in this area of research. in undertaking this paper, we focused more on quantitative researches because of their larger number, more notable achievements, and the researcher’s inclination toward them. quantitative researches the majority of papers in this area investigate responses to the research question by quantifying the collection and analysis of data. this type of research is further discussed in this section from two perspectives: the main subject and applied methodology. similar to qualitative papers, more than half of the quantitative studies focused on energy consumption (65%). among all quantitative reviewed papers, the most popular subject that has drawn the researcher’s attention is that to what extent and how occupant behaviour can affect energy consumption (becchio et al., 2016; burgas, melendez, & colomer, 2014; deng & chen, 2019; engvall, lampa, levin, wickman, & öfverholm, 2014; leroy & yannou, 2018; norford et al., 1994; park & kim, 2012; peng, rysanek, nagy, & schlüter, 2018; rafsanjani & ahn, 2016; rafsanjani, ahn, & chen, 2018; santin, 2011; song et al., 2017; virote & neves-silva, 2012; z. wang, zhao, lin, zhu, & ouyang, 2015; s. wei, jones, & de wilde, 2014; y. wei et al., 2019; xie, pan, jia, xu, & huang, 2019; zhun yu, fung, haghighat, yoshino, & morofsky, 2011; yu zhun jerry, haghighat, fung, morofsky, & yoshino, 2011; yun et al., 2014; yun & kim, 2012). many studies focused on a single form of energy consumption (either heating, cooling, electricity, dhw (demanded hot water), etc.) and dismissed the impact of occupants on other types of energy consumption. this is in analogy with the fundamentals of building physics in which building is defined as a system with different formats of energy inputs. hence, for measuring energy consumption, we need to consider all forms of energy consumption. in other words, some of the studies focused on space heating and/or cooling (engvall et al., 2014; park & journal of sustainable architecture and civil engineering 2021/2/29 90 kim, 2012; santin, 2011; song et al., 2017; z. wang et al., 2015; s. wei et al., 2014; yun & kim, 2012; yun & steemers, 2011) or even lighting (virote & neves-silva, 2012; yun & kim, 2012). they mainly studied how and to what extend occupants’ behaviour can affect the specific type of consumption, neglecting that there are some underlying formats of energy that can be affected by occupants at the same time such as energy demand associated with dhw and use of equipment. therefore, considering only one kind of energy use cannot reflect the performance of a building under the effects of different behaviours. for example, becchio et al. studied variation in energy use in a midrise apartment in italy. they measured energy consumption by the heating load, electricity use, and hot water demand. the result showed the difference between the estimated energy consumptions and the monitored data, which revealed a noticeable gap in different forms of energy consumption with a higher amount for real end uses: +50% for space heating, +19% for dhw, and +16% for electricity use. the results not only discovered a greater unprecedented discrepancy between estimated and real use but also revealed that the discrepancy exists in different formats of energy consumption to a different amount. in other words, no single form of energy consumption (space heating, space cooling, lighting, dhw, etc.) can represent the total consumption in a building and none of them can be taken into account solely. consequently, in order to study occupant behaviour effect on building energy consumption, hot water, space cooling, lighting as well as heating and ventilation should be considered as a package (becchio et al., 2016). fig. 7 type of research independent variable 9 is defined as a system with different formats of energy inputs. hence, for measuring energy 261 consumption, we need to consider all forms of energy consumption. in other words, some of the studies 262 focused on space heating and/or cooling (engvall et al., 2014; park & kim, 2012; santin, 2011; song 263 et al., 2017; z. wang et al., 2015; s. wei et al., 2014; yun & kim, 2012; yun & steemers, 2011) or 264 even lighting (virote & neves-silva, 2012; yun & kim, 2012). they mainly studied how and to what 265 extend occupants' behaviour can affect the specific type of consumption, neglecting that there are some 266 underlying formats of energy that can be affected by occupants at the same time such as energy demand 267 associated with dhw and use of equipment. therefore, considering only one kind of energy use cannot 268 reflect the performance of a building under the effects of different behaviours. for example, becchio 269 et al. studied variation in energy use in a midrise apartment in italy. they measured energy 270 consumption by the heating load, electricity use, and hot water demand. the result showed the 271 difference between the estimated energy consumptions and the monitored data, which revealed a 272 noticeable gap in different forms of energy consumption with a higher amount for real end uses: +50% 273 for space heating, +19% for dhw, and +16% for electricity use. the results not only discovered a 274 greater unprecedented discrepancy between estimated and real use but also revealed that the 275 discrepancy exists in different formats of energy consumption to a different amount. in other words, 276 no single form of energy consumption (space heating, space cooling, lighting, dhw, etc.) can 277 represent the total consumption in a building and none of them can be taken into account solely. 278 consequently, in order to study occupant behaviour effect on building energy consumption, hot water, 279 space cooling, lighting as well as heating and ventilation should be considered as a package (becchio 280 et al., 2016). 281 282 fig. 7. type of research independent variable 283 some of the studied papers addressed the important factor of comfort in studying occupant's energy-284 driven behaviour to some extends, in form of thermal comfort (kim et al., 2017; newsham, 1997; 285 pellegrino et al., 2016), visual comfort (kim et al., 2017; yun & kim, 2012) and air quality (engvall 286 et al., 2014; iwashita & akasaka, 1997; kim et al., 2017). kim et al investigate the optimal occupant 287 behaviour that can simultaneously reduce total energy consumption and improve indoor comfort. they 288 used an energy simulation and particle swarm optimization algorithm in modeling a school in five 289 different cities. they managed to decrease energy consumption by 14.6 % in comparison to the basic 290 model only by optimizing occupant's interaction with the building (kim et al., 2017). in another study, 291 some of the studied papers addressed the important factor of comfort in studying occupant’s energy-driven behaviour to some extends, in form of thermal comfort (kim et al., 2017; newsham, 1997; pellegrino et al., 2016), visual comfort (kim et al., 2017; yun & kim, 2012) and air quality (engvall et al., 2014; iwashita & akasaka, 1997; kim et al., 2017). kim et al investigate the optimal occupant behaviour that can simultaneously reduce total energy consumption and improve indoor comfort. they used an energy simulation and particle swarm optimization algorithm in modeling a school in five different cities. they managed to decrease energy consumption by 14.6 % in comparison to the basic model only by optimizing occupant’s interaction with the building (kim et al., 2017). in another study, pellegrino et al, simulated and validated data about indoor air quality in 18 typical indian apartments and compared the effect of the low-cost intervention for reducing energy demand. results revealed that indoor air is more stable and independent from the outdoor thermal condition, than simulation suggests. they mentioned that leaving simulation input to the default schedule for occupancy, internal loads, and natural ventilation can increase inaccuracy significantly. they also showed that the use of night natural ventilation has a pivotal effect on the thermal performance of buildings in the city of kolkata (pellegrino et al., 2016). 91 journal of sustainable architecture and civil engineering 2021/2/29 researchers also paid attention to the impact of occupant behaviour on the economic side of the building sector (mohamed, al-habaibeh, abdo, & elabar, 2015; s. wang et al., 2017; yun & steemers, 2011). in a study, ahemd et al. evaluate the effect of domestic energy consumption and occupants’ behaviour pattern on the national scale energy consumption in libya and how this could affect the peak demand, capacity and energy budget. the result of their study reveals that energy-conscious behaviour coupled with utilizing more efficient appliances and lighting systems could significantly save energy up to a large power station of 2 gw (mohamed et al., 2015). determining behaviour deriver (alam et al., 2017; hong et al., 2015) and occupancy pattern (yun & kim, 2012) for enhancing the accuracy of simulation results was also among the topics in the reviewed papers with less frequency. bedir and kara in their paper analyzed electrical appliance use in the dutch housing stock and identified behavioural patterns and profiles of electricity consumption. the result of their study can lead to more accurate results of simulation studies for reporting electricity needs (bedir & kara, 2017). this was an example of a limited number of papers focusing on occupancy profile because the majority of researches regard the dependant variable with a psychological approach including biological, psychological, socioeconomic, sociodemographic, and contextual factors, which is out of the scope of this review. research variables the second most popular issue among the reviewed papers was conducted aiming to configure near-real occupancy scenarios. only 11% of the reviewed studies deal with the behaviour patterns or occupancy profile in response to the urgent demand for accurate occupancy patterns utilized in simulation tools (bedir & kara, 2017; z. yu et al., 2015; yun & kim, 2012). in terms of the parameters influencing occupants’ energy behaviours, comfort conditions (thermal, visual, and air quality) have been taken into account in 20% of papers. considering the fact that indoor environmental quality (ieq) factors may have a contradictory impact on different forms of comfort conditions, almost in all research, occupants’ behaviour was studied assuming only one form of table 1 dependent variable in studied papers parameter variable number percentage energy consumption total load 15 43% space heating & cooling load 1 2.8% only space cooling load 1 2.8% only space heating load 5 14% overall 22 63% thermal comfort ppd 2 6% cidh 1 2.8% overall 3 8.5% visual comfort lux 2 6% occupant pattern 2 6% profile 2 6% framework 1 2.8% overall 4 11% finance 2 6% air quality co2 1 2.8% ventilation rate and air temperature 1 2.8% overall 2 6% journal of sustainable architecture and civil engineering 2021/2/29 92 comfort condition. this has been either iaq (indoor air quality) (iwashita & akasaka, 1997; kim et al., 2017), thermal (kim et al., 2017; newsham, 1997; pellegrino et al., 2016), or visual comfort(kim et al., 2017; yun & kim, 2012). researchers measured the cidh (comfort indoor degree hours) or ppd (predicted percentage of dissatisfied) index as indicators for comfort conditions. it is important to keep in mind that occupant behaviour is a dynamic phenomenon and building occupants change their behaviour to provide general comfort conditions, therefore there is a crucial gap in this area and need occupant energy-driven behaviour to be addressed under complete comfort conditions. in the bottom, 6% of the quantitative papers addressed financial issues (mohamed et al., 2015; s. wang et al., 2017) and almost the same amount investigate air quality (measuring the co2 concentration, ventilation rate, etc.). table 2 reports a quantitative summary of the investigated independent variables. results show that the effect of occupant behaviour on visual comfort in buildings has not been investigated sufficiently. considering visual conditions as an important part of overall comfort in future studies can fill this gap. this can be conducted by measuring the illuminance level, as an important, measurable, and comprehensive variable to assess visual comfort and functionality of a space. methods for data collection experimental methods to cluster the applied methodology, three major methods and combinations of them can summarize how researchers collect data in quantitative studies: simulation studies, experiments, and questionnaires. as shown in fig. 8 the majority of the studies in this realm are conducted by experimental studies. the most implemented field measurement methods are pre and post-occupancy surveys as well as occupant monitoring using sensors or observation, and questionnaires. experiment has been the sole method of the study or in some cases has been backed up with simulation(becchio et al., 2016; norford et al., 1994; rafsanjani & ahn, 2016; xie et al., 2019; yun et al., 2014) or data analysis(pellegrino et al., 2016). a few studies used a hybrid method for data collection and benefit from all three methods to evaluate their research hypothesis precisely(song et al., 2017; z. wang et al., 2015). it is also observed that researchers regard simulations and survey evenly in this area. besides quantitative methods, researchers also used descriptive and analytical methods as well although they are applied in fewer studies(alam et al., 2017; mohamed et al., 2015; yun & steemers, 2011). in a comprehensive study, gilani and o’brien provide a complete description of in-situ monitoring methods, technologies, and challenges to study occupant’s behaviour. they highlighted the fig. 8 diagram of data collecting method frequency in quantitative researches. 12 by mixed research methods, such as adding surveys to traditional sensor-based monitoring campaigns. 364 next, the authors discuss some of the major methodological challenges including (gilani et al., 2017). 365 366 fig. 8. diagram of data collecting method frequency in quantitative researches. 367 2.5.2 simulation: 368 simulation is the second most popular method in quantifying the effect of occupant behaviour on 369 building energy consumption. in recent years with the advent of new software and analysis engines, 370 there are numerous options ahead of researchers for making a simulation model. accuracy and valid 371 results, ease of application, and model-making process are the most important criteria to choose 372 software in simulation studies. fig. 9 summarizes the application of software in behaviour studies. as 373 shown in the graph energyplus (pellegrino et al., 2016; xie et al., 2019; yun et al., 2014)and dest 374 (rafsanjani & ahn, 2016; z. wang et al., 2015) are widely used to simulate the energy-driven 375 behaviour of occupants. 376 377 378 fig. 9. the most popular software 379 feng et al. in their paper discuss an important challenge in bps. they determined an adequate number 380 of simulations for statistically representative probabilistic building performance in commercial 381 buildings. in their research, they focused on the appropriate repetition in occupant behaviour 382 simulation. by comparing the results of space cooling consumption with several input time intervals, 383 they recommended 10 repetitions as appropriate simulation repetition and temporal discretization in 384 building simulation considering occupant behaviour (feng et al., 2016). 385 386 2.5.3 questionnaire: 387 advantages as the reality of the obtained data, the potential for large sample size and long-term data collection at relatively low cost, and future sensing technologies. they also find the shortcomings of this method of study in the issues with stand-alone and connected sensors, impediments to achieving a large sample size, the hawthorne effect, and the errors of self-reporting. they also emphasized the benefits, afforded by mixed research methods, such as adding surveys to traditional sensor-based monitoring campaigns. next, the authors discuss some of the major methodological challenges including (gilani et al., 2017). 93 journal of sustainable architecture and civil engineering 2021/2/29 simulation simulation is the second most popular method in quantifying the effect of occupant behaviour on building energy consumption. in recent years with the advent of new software and analysis engines, there are numerous options ahead of researchers for making a simulation model. accuracy and valid results, ease of application, and model-making process are the most important criteria to choose software in simulation studies. fig. 9 summarizes the application of software in behaviour studies. as shown in the graph energyplus (pellegrino et al., 2016; xie et al., 2019; fig. 9 the most popular software 12 by mixed research methods, such as adding surveys to traditional sensor-based monitoring campaigns. 364 next, the authors discuss some of the major methodological challenges including (gilani et al., 2017). 365 366 fig. 8. diagram of data collecting method frequency in quantitative researches. 367 2.5.2 simulation: 368 simulation is the second most popular method in quantifying the effect of occupant behaviour on 369 building energy consumption. in recent years with the advent of new software and analysis engines, 370 there are numerous options ahead of researchers for making a simulation model. accuracy and valid 371 results, ease of application, and model-making process are the most important criteria to choose 372 software in simulation studies. fig. 9 summarizes the application of software in behaviour studies. as 373 shown in the graph energyplus (pellegrino et al., 2016; xie et al., 2019; yun et al., 2014)and dest 374 (rafsanjani & ahn, 2016; z. wang et al., 2015) are widely used to simulate the energy-driven 375 behaviour of occupants. 376 377 378 fig. 9. the most popular software 379 feng et al. in their paper discuss an important challenge in bps. they determined an adequate number 380 of simulations for statistically representative probabilistic building performance in commercial 381 buildings. in their research, they focused on the appropriate repetition in occupant behaviour 382 simulation. by comparing the results of space cooling consumption with several input time intervals, 383 they recommended 10 repetitions as appropriate simulation repetition and temporal discretization in 384 building simulation considering occupant behaviour (feng et al., 2016). 385 386 2.5.3 questionnaire: 387 yun et al., 2014)and dest (rafsanjani & ahn, 2016; z. wang et al., 2015) are widely used to simulate the energy-driven behaviour of occupants. feng et al. in their paper discuss an important challenge in bps. they determined an adequate number of simulations for statistically representative probabilistic building performance in commercial buildings. in their research, they focused on the appropriate repetition in occupant behaviour simulation. by comparing the results of space cooling consumption with several input time intervals, they recommended 10 repetitions as appropriate simulation repetition and temporal discretization in building simulation considering occupant behaviour (feng et al., 2016). questionnaire fig. 10 shows the number of studied cases in an individual paper according to the research method. as the graph shows, the highest numbers of monitored cases in research, are observed in survey-based papers. researchers prefer questionnaires for collecting data when investigating behaviour on large scale is needed. among the reviewed papers in the current study, questionnaires with an average of 372 have the most cases. however far more questionnaires are needed in calculation-based studies. ahmed et al. collected 429 valid questionnaires to evaluate the effect of domestic energy consumption behaviour on overall energy consumption in libya and the way it affects the peak demand, capacity, future trends, and national energy budget (mohamed et al., 2015). yun and steemers in their research investigated the significance of behavioural, physical, and socio-economic parameters on cooling demand in residential buildings through 2718 buildings in columbia state, usa(yun & steemers, 2011). in researches using simulation for data collection, a considerably lower number of studied cases is observed. the decrease in the number fig 10 number of studied cases in a single research according to data collection method (exp= experimental methods, q= questionnaire, s=simulation and model making) 13 fig. 10 shows the number of studied cases in an individual paper according to the research method. 388 as the graph shows, the highest numbers of monitored cases in research, are observed in survey-based 389 papers. researchers prefer questionnaires for collecting data when investigating behaviour on large 390 scale is needed. among the reviewed papers in the current study, questionnaires with an average of 391 372 have the most cases. however far more questionnaires are needed in calculation-based studies. 392 ahmed et al. collected 429 valid questionnaires to evaluate the effect of domestic energy consumption 393 behaviour on overall energy consumption in libya and the way it affects the peak demand, capacity, 394 future trends, and national energy budget (mohamed et al., 2015). yun and steemers in their research 395 investigated the significance of behavioural, physical, and socio-economic parameters on cooling 396 demand in residential buildings through 2718 buildings in columbia state, usa(yun & steemers, 397 2011). in researches using simulation for data collection, a considerably lower number of studied cases 398 is observed. the decrease in the number of cases in the simulation-based or assisted method is due to 399 the time-consuming process of simulation, which is still a challenge to apply white-model simulations. 400 in some studies, however, the researcher decides to evaluate, support, or boost data from the 401 questionnaires, with an experimental method, such as field measurement. in these cases due to time 402 consuming and difficult process of in-situ measurement, the number of studied cases drops 403 remarkably. experimental methods are also applied as the data collection method in research, 404 especially in cases that accuracy and thorough analysis of the mechanism of energy consumption was 405 of great importance rather than figuring the pattern in vast samples. 406 407 fig 10. number of studied cases in a single research according to data collection method (exp= 408 experimental methods, q= questionnaire, s=simulation and model making) 409 410 simulation as the third method of data collection was also used extensively, mostly in studies with a 411 limited domain of research. among the reviewed papers, a simulation was taken into account in 412 projects with a limited number of cases (“bp-stats-review-2018-all-data,” n.d.; kim et al., 2017; 413 newsham, 1997; pellegrino et al., 2016; xie et al., 2019). this method is not suggested in large-scale 414 studies due to modeling difficulties, calculation inaccuracies and limited computing power of current 415 devices and software. on an urban scale normal statistical method was applied (alam et al., 2017; 416 mohamed et al., 2015). in a number of studies, three methods of data gathering were applied in order 417 to understand the subject deeper (deng & chen, 2019; song et al., 2017; z. wang et al., 2015; c. yu, 418 du, & pan, 2019). this type of hybrid data-gathering method is yet rare to find. 419 420 1 101 201 301 401 501 601 n um be r o f s tu di ed c as es individual paper exp exp+q exp+s exp+q+s q s journal of sustainable architecture and civil engineering 2021/2/29 94 of cases in the simulation-based or assisted method is due to the time-consuming process of simulation, which is still a challenge to apply white-model simulations. in some studies, however, the researcher decides to evaluate, support, or boost data from the questionnaires, with an experimental method, such as field measurement. in these cases due to time consuming and difficult process of in-situ measurement, the number of studied cases drops remarkably. experimental methods are also applied as the data collection method in research, especially in cases that accuracy and thorough analysis of the mechanism of energy consumption was of great importance rather than figuring the pattern in vast samples. simulation as the third method of data collection was also used extensively, mostly in studies with a limited domain of research. among the reviewed papers, a simulation was taken into account in projects with a limited number of cases (“bp-stats-review-2018-all-data,” n.d.; kim et al., 2017; newsham, 1997; pellegrino et al., 2016; xie et al., 2019). this method is not suggested in largescale studies due to modeling difficulties, calculation inaccuracies and limited computing power of current devices and software. on an urban scale normal statistical method was applied (alam et al., 2017; mohamed et al., 2015). in a number of studies, three methods of data gathering were applied in order to understand the subject deeper (deng & chen, 2019; song et al., 2017; z. wang et al., 2015; c. yu, du, & pan, 2019). this type of hybrid data-gathering method is yet rare to find. discussion as mentioned in section 2 of this paper, the impact of occupant’s behaviour on building consumption is a growing research interest. numerous studies have investigated the direct or indirect impact of occupants and their behaviour on the energy consumption in different buildings with the ultimate goal of reducing the total energy use or mitigating the performance gap between the predicted and actual energy consumption of buildings. this paper reviewed the most recent related publications related to occupant energy behaviour in buildings to identify different scientific approaches to studying the complex behaviour of occupants and how it affect total energy consumption in buildings. to reach this, reviewed papers were categorized in terms of different perspectives such as building type, building typology, building morphology, dependent variables, research type, data gathering method, number of cases, climate, and location distribution. the evolutionary trend of research the number of projects regarding occupant-driven building energy is truly increasing through the studied period especially after 2011. among the studies period, there were years with a significantly fewer number of published papers. to determine the trends and hot topics, the authors decided to conduct a qualitative method with the tool of interviews. the aim of the qualitative section of the study is first to help gathering information on independent variables, scope, goals, and other characteristics of the researches in gap years and secondly, to validate the reliability of the trends derived from papers. as mentioned previously, selected participants in the interviews are experts and certified specialists in simulation and building energy studies. the interview continued to reach repetitive results, which shows the saturation. the result of the interview analysis was in convergence with the review study. it reveals that respectively comfort conditions (fabi, andersen, corgnati, & olesen, 2012; hong et al., 2015; rafsanjani & ahn, 2016; salcido, raheem, & issa, 2016; z. wang et al., 2015; s. wei et al., 2014), payback period, and financial aspect of energy conservation strategies (juodis, jaraminiene, & dudkiewicz, 2009; nicol & humphreys, 2002; sorrell, dimitropoulos, & sommerville, 2009) are the hottest research topics in the 2000s. in fig. 11 (underlined items are added from a qualitative method.) fig. 11 shows the evolutionary trend of the research community in this field and summarizes the most remarkable milestones and achievements per year. as the figure shows, the trend of scientific studies commenced proving the gap between anticipated and real consumption and estimating the amount of this gap roughly. in the next level, researchers focused on the leading rea95 journal of sustainable architecture and civil engineering 2021/2/29 sons for this gap, most consider them as single-external-nonrelated factors (such as clo-factor, met factor, interactions with building, etc.). in the second decade, more researches with diverse approaches, are observed investigating the side effects of this discrepancy and a further investigation of the reasons. for instance, some researches have been conducted with an economic approach dealing with the financial break of sustainable building projects due to inaccuracy of energy estimation and payback period (sorrell et al., 2009) as well as other researches investigating difficulties in modelling behaviour due to psychological reasons (indraganti & rao, 2010; juodis et al., 2009; leroy & yannou, 2018). as the research in this area continued, more projects aimed to mitigate this gap, not considering the origins and essence of influential factors, but the effects and consequences. in the last section of the studied period, which is still being pursued, researchers have found out that as many influencing factors as possible should be addressed simultaneously. they managed to tie them up under the occupants’ comfort (deng & chen, 2019; engvall et al., 2014; kim et al., 2017; pellegrino et al., 2016). in recent publications, researchers have focused on the relation of comfort conditions and related energy consumption by new methods and utilizing advanced technologies (hong et al., 2015; marique, de meester, de herde, & reiter, 2014; rafsanjani et al., 2018). this recent trend has succeeded to mitigate the gap more than ever, therefore it is still a popular research trend in recent years. the investigations of this study that result in determining the scientific trend in this area are totally in line with other reviews although it adds more insights to them. o’brien et al. in a paper investigate the most recent achievements in occupant behaviour research. they categorize research stages into phases of data collection, modelling and simulation and explain fundamentals through literature. they emphasize the remaining questions to be addressed in future studies. they speculate that occupant modeling and simulation are still in the primitive phase. they refer to gartner’s hype cycle and evaluate occupant researches in the early stages (gilani et al., 2017). modelling occupant behaviour according to the reviewed papers, it is concluded that one of the main reasons for energy simulation inaccuracy is the inaccurate assumption for occupant behaviour. in other words, occupants’ active and passive energy behaviours (including window opening, use of solar shading and blinds, adjusting hvac set points, use of hot water, etc.) are not considered completely and correctly in current energy analysis tools. thus, there is a noticeable demand to improve the results of energy modeling by reflecting the behaviour of occupants in simulation studies. this can be fulfilled by defining more accurate and near-real occupancy profiles in energy simulation tools, however, it could not be done without facing several challenges; the main challenge in this part is the complexity and dynamic nature of occupants’ energy behaviour, which is influenced by various 15 publications, researchers have focused on the relation of comfort conditions and related energy 464 consumption by new methods and utilizing advanced technologies (hong et al., 2015; marique, de 465 meester, de herde, & reiter, 2014; rafsanjani et al., 2018). this recent trend has succeeded to 466 mitigate the gap more than ever, therefore it is still a popular research trend in recent years. 467 468 469 fig. 11. timeline of highlights: occupant behaviour in energy simulation studies. 470 the investigations of this study that result in determining the scientific trend in this area are totally in 471 line with other reviews although it adds more insights to them. o’brien et al. in a paper investigate the 472 most recent achievements in occupant behaviour research. they categorize research stages into phases 473 of data collection, modelling and simulation and explain fundamentals through literature. they 474 emphasize the remaining questions to be addressed in future studies. they speculate that occupant 475 modeling and simulation are still in the primitive phase. they refer to gartner’s hype cycle and 476 evaluate occupant researches in the early stages (gilani et al., 2017). 477 478 table 2. summary of data from quantitative reviewed papers 479 author year dependent variable data gathering method climate* location building type building typology building morpholog y number of studied cases in the paper 1 z. deng q. chen (deng & chen, 2019) 2019 ec questionnaire & simulation & experiment dfa west lafayette commercial mid-rise detached 20 2 c. yu et al. (c. yu et al., 2019) 2019 ec questionnaire & simulation & experiment cwa hong kong residential high-rise detached 988 3 j. xiea et al. (xie et al., 2019) 2019 ec experimental & simulation cwa shanghai residential high-rise detached 315 4 j. rouleau et al. (rouleau, gosselin, & blanchet, 2019) 2019 experimental & simulation dfb quebec city residential high-rise na 40 5 h. nabizadeh rafsanjani et al. (rafsanjani et al., 2018) 2018 ec experimental bsk nebraska educational low-rise detached 2 fig. 11 timeline of highlights: occupant behaviour in energy simulation studies journal of sustainable architecture and civil engineering 2021/2/29 96 author year dependent variable data gathering method climate* location building type building typology building morphology number of studied cases in the paper 1 z. deng q. chen (deng & chen, 2019) 2019 ec questionnaire & simulation & experiment dfa west lafayette commercial mid-rise detached 20 2 c. yu et al. (c. yu et al., 2019) 2019 ec questionnaire & simulation & experiment cwa hong kong residential high-rise detached 988 3 j. xiea et al. (xie et al., 2019) 2019 ec experimental & simulation cwa shanghai residential high-rise detached 315 4 j. rouleau et al. (rouleau, gosselin, & blanchet, 2019) 2019 experimental & simulation dfb quebec city residential high-rise na 40 5 h. nabizadeh rafsanjani et al. (rafsanjani et al., 2018) 2018 ec experimental bsk nebraska educational low-rise detached 2 6 m. oritz p. bluyssen (ortiz & bluyssen, 2018) 2018 questionnaire cfb amsterdam residential low-rise semidetached 316 7 y. leroy, b. yannou (leroy & yannou, 2018) 2018 ec questionnaire cfb (majority) france residential national scale 8 y. peng et al. (peng et al., 2018) 2018 ec experimental cfb switzerland commercial mid-rise semidetached 11 9 l. songa et al.(song et al., 2017) 2017 ec** questionnaire & simulation & experiment cfa shanghai residential high-rise detached 10 10 j. kim et al.(kim et al., 2017) 2017 ec thermal comfort visual comfort air quality simulation cfa, dfb, dwa, dwa, dwa london, new york, seoul, beijing, ulsan educational mid-rise detached 5 11 m. bedir, e. cara(bedir & kara, 2017) 2017 ob*** pattern questionnaire & experiment cfb netherlands. residential low-rise & mid-rise attached 323 12 s. wanga, a. kim, e. johnson(s. wang et al., 2017) 2017 financial issue simulation csb bellevue in washington state commercial mid-rise detached 100 13 c. becchio et al.(becchio et al., 2016) 2016 ec experiment & simulation cfa csa turin residential mid-rise detached 1 14 m. ouf, m. issaa, p. merkelb(ouf et al., 2016) 2016 ec experiment dfb manitoba educational low-rise detached 126 15 h. nabizadehrafsanjani, a. changbumahna(rafsanjani & ahn, 2016) 2016 ec experiment & simulation dfa nebraska commercial mid-rise detached 16 m. pellegrino, m. simonetti, g. chiesa(pellegrino et al., 2016) 2015 thermal comfort simulation aw kolkata residential mid-rise attached 1 17 z. yu et al. (z. yu et al., 2015) 2015 ec experiment cfa honzyo, tohoku japan residential low-rise detached 1 table 2. summary of data from quantitative reviewed papers 97 journal of sustainable architecture and civil engineering 2021/2/29 author year dependent variable data gathering method climate* location building type building typology building morphology number of studied cases in the paper 1 z. deng q. chen (deng & chen, 2019) 2019 ec questionnaire & simulation & experiment dfa west lafayette commercial mid-rise detached 20 2 c. yu et al. (c. yu et al., 2019) 2019 ec questionnaire & simulation & experiment cwa hong kong residential high-rise detached 988 3 j. xiea et al. (xie et al., 2019) 2019 ec experimental & simulation cwa shanghai residential high-rise detached 315 4 j. rouleau et al. (rouleau, gosselin, & blanchet, 2019) 2019 experimental & simulation dfb quebec city residential high-rise na 40 5 h. nabizadeh rafsanjani et al. (rafsanjani et al., 2018) 2018 ec experimental bsk nebraska educational low-rise detached 2 6 m. oritz p. bluyssen (ortiz & bluyssen, 2018) 2018 questionnaire cfb amsterdam residential low-rise semidetached 316 7 y. leroy, b. yannou (leroy & yannou, 2018) 2018 ec questionnaire cfb (majority) france residential national scale 8 y. peng et al. (peng et al., 2018) 2018 ec experimental cfb switzerland commercial mid-rise semidetached 11 9 l. songa et al.(song et al., 2017) 2017 ec** questionnaire & simulation & experiment cfa shanghai residential high-rise detached 10 10 j. kim et al.(kim et al., 2017) 2017 ec thermal comfort visual comfort air quality simulation cfa, dfb, dwa, dwa, dwa london, new york, seoul, beijing, ulsan educational mid-rise detached 5 11 m. bedir, e. cara(bedir & kara, 2017) 2017 ob*** pattern questionnaire & experiment cfb netherlands. residential low-rise & mid-rise attached 323 12 s. wanga, a. kim, e. johnson(s. wang et al., 2017) 2017 financial issue simulation csb bellevue in washington state commercial mid-rise detached 100 13 c. becchio et al.(becchio et al., 2016) 2016 ec experiment & simulation cfa csa turin residential mid-rise detached 1 14 m. ouf, m. issaa, p. merkelb(ouf et al., 2016) 2016 ec experiment dfb manitoba educational low-rise detached 126 15 h. nabizadehrafsanjani, a. changbumahna(rafsanjani & ahn, 2016) 2016 ec experiment & simulation dfa nebraska commercial mid-rise detached 16 m. pellegrino, m. simonetti, g. chiesa(pellegrino et al., 2016) 2015 thermal comfort simulation aw kolkata residential mid-rise attached 1 17 z. yu et al. (z. yu et al., 2015) 2015 ec experiment cfa honzyo, tohoku japan residential low-rise detached 1 author year dependent variable data gathering method climate* location building type building typology building morphology number of studied cases in the paper 18 a. mohamed et al.(mohamed et al., 2015) 2015 ob financial results in large scale questionnaire (available data) bwh the middle east and north africa (mena) region, residential low-rise attached 429 19 z. wang et al.(z. wang et al., 2015) 2015 ec questionnaire & simulation & experiment cfa cfa cfa shanghai, chongqing, jiangsu. residential high-rise detached 27 20 g. yun, j. choi, j. kim(yun et al., 2014) 2014 ec experiment & simulation dwa suwon, korea office midrise attached 2 21 k. engvalla et al.(engvall et al., 2014) 2014 ec questionnaire (available data) cfb stockholm residential low-rise & midrise detached 374 22 l. burgas, j. melendez, j. colomer(burgas et al., 2014) 2014 ec experiment cfa girona educational low-rise & midrise & highrise detached 10 23 g. young yun, h. kim, j.tai kim(yun et al., 2014) 2012 visual comfort ec occupancy pattern experiment dwa seoul office low-rise attached 4 24 j. virotea, r. nevessilvab(virote & neves-silva, 2012) 2012 ec simulation not stated not stated na na detached na 25 j.s. park, h.j. kimb(park & kim, 2012) 2012 ec questionnaire & experiment dwa seoul residential low-rise & midrise detached 139 26 o. santin(santin, 2011) 2011 ec questionnaire cfb netherlands utrecht hague residential low-rise detache , semidetached, terraced and corner houses, maisonettes and flats. 313 27 g. young yun, k. steemers(yun & steemers, 2011) 2011 ec questionnaire colombia state, us residential low-rise & midrise detached, attached 2718 28 z. yu et al.(yu zhun jerry et al., 2011) 2011 ec questionnaire & experiment dfb, cfa, cfa, cfa, af, cfa hokkaido, tohoku, hokuriku, kanto, kansai, kyushu residential low-rise detached 66 29 z. yua et al.(zhun yu et al., 2011) 2011 ec questionnaire & experiment dfb, cfa, cfa, cfa, af, cfa hokkaido, tohoku, hokuriku, kanto, kansai, kyushu residential low-rise & midrise detached 67 30 g. newsham (newsham, 1997) 1997 thermal comfort simulation dfa toronto office low-rise single, southfacing room 1 31 g. iwashita, h. akasaka(iwashita & akasaka, 1997) 1997 ventilation rate questionnaire & experiment cfa kagoshima, the southern part of japan, residential high-rise detached 8 32 l.k. norford et al.(norford et al., 1994) 1994 ec experiment & simulation cfa central new jersey office midrise detached 1 ec – energy consumption ob – occupant behaviour * based on koppen-geiger climatic classification journal of sustainable architecture and civil engineering 2021/2/29 98 psychological, climatic and contextual factors. therefore, occupants’ interaction with the building needs to be studied in a multidisciplinary approach to incorporate driving factors from sociological, psychological, economics, engineering, and design perspectives to obtain a much more accurate occupancy profile. this way, real-time interactions with the building can be correctly reflected and help in generating more realistic assumptions in building energy prediction. an alarming point observed in the reviewed papers is that researchers need to pay attention to the level of simplification in modelling real conditions. occupants change behaviour to provide comfort, often regardless of energy. the sensible and crucial factor for the occupant is total comfort. that is in analogy with some researches in which only one format of energy consumption or one form of comfort condition is addressed. this is due to the complexity in comfort calculation and is an attempt to simplify the condition. in some iterations, the researcher may manage to reduce energy consumption under simplified comfort conditions by changing the behaviour but has exerted a negative impact on other types of comfort. for instance, interactions with windows, shades, and blinds can help to provide thermal comfort and reducing consumption while simultaneously may hurt visual comfort and overall shows a negative effect on comfort condition. it is highly recommended to investigate the differences made by occupant behaviour on energy consumption in near-real conditions. to address this flaw in more developed researches is needed. measuring and monitoring ieq can be a good way to evaluate comfort conditions while behaviour changes. accordingly, researchers and scholars in this field need to pay more attention to comfort conditions and apply more accurate modelling of the real environment. moreover, there is a strong need to bring scientific achievement into comfort simulation and apply more advanced calculations and simulation tools in this regard. in this paper, a comprehensive literature review was conducted by elaborating a theoretical framework to study the potential impact of occupant behaviour on energy consumption in buildings from all over the world. this literature review aims to look into remarkable achievements and knowledge gap in this field of research, as well as investigating significant trends in the last three decades as a required step for predicting future trends in this topic. the result of this review showed that the occupant behaviour has a big impact on energy consumption and the comfort condition, which has not been reflected accurately in simulation studies due to its dynamic and complex nature. the analysis of the literature highlight that a comprehensive approach to identifying the effect of occupants’ behaviour in real comfort condition has not yet been conducted. most studies focus on either determining occupant’s simplified interaction with the building or monitoring energy consumption under one form of comfort (either thermal, visual, etc.) which is not an extraction of real condition in the built environment. neglecting the fact that different forms of comfort are interwoven and inseparable in real conditions, has lead to inaccuracy in simulation results. it is also ignored that indoor environmental factors may have a contradictory effect on different forms of comfort. in this sense, authors suggest conducting similar research considering real comfort conditions via experiments and in-situ studies and using cidh based assessment. the results also revealed that a significant number of existing studies focused on evaluating energy-sensitive behaviour in specific regions and cultures from developed countries. currently, modelers in regions with a limited research background in this area, tend to generalize the results of available studies, which results in wrong assumptions, and inaccuracy of simulation results. considering socio-cultural forces in forming occupant behaviour, there is a strong need to conduct more research in less regarded regions. also with the advent of new technology in simulating occupant behaviour, such as smart learning agents and meta-models, it is anticipated that this field of 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(2011). behavioural, physical and socio-economic factors in household cooling energy consumption. applied energy, 88(6), 2191-2200. https://doi.org/10.1016/j.apenergy.2011.01.010 mahsa torabi researcher hal (high-performance architecture) main research area energy simulation modeling, life cycle assessment, artificial intelligence in architecture occupant behaviour address department of architecture, faculty of art and architecture, tarbiat modares university, al-ahmad, tehran iran. tel. +989125146905 e-mail: mst.torabi@modares.ac.ir mohammadjavad mahdavinejad professor department of architecture, & dean of highperformance architecture laboratory, tarbiat modares university, tehran, iran main research area high-performance architecture, designerly approach to computational energy address department of architecture, faculty of art and architecture, tarbiat modares university, al-ahmad, tehran iran. tel. +98-21-82883739. e-mail: mahdavinejad@modares.ac.ir about the authors this article is an open access article distributed under the terms and conditions of the creative commons attribution 4.0 (cc by 4.0) license (http://creativecommons.org/licenses/by/4.0/). 54 darnioji architektūra ir statyba 2014. no. 2(7) journal of sustainable architecture and civil engineering issn 2029–9990 concept of smart city: first experience from city of riga zajacs aleksandrs*, zemitis jurgis ,tihomirova kristina, borodinecs anatolijs riga technical university, faculty of civil engineering, institute of heat, gas and water technology, azenes str. 16/20, lv-1010, riga, latvia. *corresponding author: aleksandrs.zajacs@rs.lv http://dx.doi.org/10.5755/j01.sace.7.2.6932 growing concern of smart city development and urban resilience has become increasingly embedded in urban planning, national security and energy policy. one of the main city documents focused on actions and measures to be implemented in city is sustainable energy action plan. taking into account specifics of modern cities and future city development at smart city level the existing sustainable energy action plans should be enhanced. nowadays it is necessary to bring existing standalone energy actions at cross sector level in order to ensure urban resilience. currently there are 3414 cities across the europe and eastern partners which already have developed sustainable energy action plan. the paper draws attention to areas with high impact to smart city development. in terms of smart cities the most powerful actions are those which directly affect at least these three sectors – energy, ict and transport. paper provides some good practice examples from city of riga. the losses of the heat transmitted to consumers by jsc “rigas siltums” – main heat supplier of riga have been decreased by 667 thous. mwh or 2.45 times in comparison to year 1996/1997. following the completion of reconstruction of the boiler houses, construction of a biofuel fired water heating boiler, construction of the biofuel fired cogeneration plant, installation of flue gas condensers for biofuel fired boilers at the dhp the share of biofuel utilisation within the fuel balance of the jsc „rīgas siltums” will reach 20.4 % in fiscal year 2013/2014. the total energy produced from renewable energy sources since 01.01.1996 until 8.04.2014 is 920463.107 mwh. the project “heat meters automatic remote reading system” proved to be a successful and reliable solution for the control and accounting of consumed heat, as well as related tasks enabling “online communication” with 8000 individual heating units throughout the riga city. development and introduction of electric cars and filling station infrastructure in riga was one more step on the way to the smart city status. despite a fairly long payback period electric cars are quite beneficial solution for some companies whose activities are related with vehicles’ high mileage within the city as llc “rigas satiksme”. keywords: smart city, sustainable resources, urban resilience. 1. introduction during recent years, people have become aware that environment in the city is comprehensive resource that requires smart management. this has lead to increased need for use of sustainable resources and development of sustainable cities with integrated smart disciplines – economics, energies, technologies, architecture and politics. major attention must also be paid to city resilience planning due to its importance for any city’s development as well as the national securitization process by becoming better prepared and more responsible for national risk management. city security and public resilience have become increasingly embedded in urban planning, national security and energy policy (coaffee j., 2008). city designers should remember that a smart city involves not only smart technologies, but also smart economy, governance, mobility, living, environment and people (giffinger et al., 2007). the key concepts of urban resilience are sustainability and adaptation to climate changes (leichenko r., 2011). by words “city resilience” typically is understood – sustainable energy management, securing stable energy supply, reducing energy consumption, developing renewable energy sources (coaffee j., 2008) and also security policy focused on terrorist hazards and natural disasters (collier et al., 2013). this paper explains the synergy between main city dimensions such as energy, economics and stakeholders and different urban sector development levels. the aim of this paper was to draw attention to areas with high impact to smart city development process. 55 2. city strategic energy action plan modern cities can achieve eu20-20-20 goal only by improvements in all major sectors such as buildings, energy and transport. each european city is free to choose their approach for achievement of eu20-20-20 target. the main document which defines actions and measures to be implemented in each city in order to reach co2 reduction by 20 % is sustainable energy action plan (seap). according to covenant of mayor (www.covenantofmayors.eu) data there are 3414 cities across the europe and eastern partners which already have sustainable energy action plan. typical sustainable energy action plan is focused on standalone actions such as insulation of buildings, use of efficient lighting, local renewable energy sources and etc. nowadays the existing seap should be enhanced taking into account requirements for smart cities. although there is no global definition of smart city (neirotti et al., 2014) the smart cities general concept can be characterized as improvement of urban performance by implementation of information and communication technologies (ict) and by engagement of stakeholders. in addition more crosssector energy actions should be introduced. currently there are activities to start standardization activities in field of sustainable development and smart cities (marsal_llacuna et al., 2014). efficiency and impact of each energy action should be evaluated on 3d scale taking into account sector, city dimension and implementation scale. the major city dimensions which characterize each energy action are “energy and technology”, “economics and finance” and “organization and stakeholders”. interaction between city dimensions and scale for each sector is shown in fig. 1. each indicator impact is evaluated at implementation scale. this approach enables us to understand whether the implementation of actions is proportional to the city’s scale and dimension in each sector. fig. 1. evaluation of dimension and scale of energy actions for example, if city wants to realize existing building renovation at city scale the “economics and finance” and “organization and stakeholders” should be addressed at proper level. the public/private finances should be used including esco (energy service company) model and active work with wide range of stakeholder groups is necessary. example of “energy and technology” indicator of building renovation process at different scale is shown in fig. 2. fig. 2. example of building renovation process on “energy and technology” dimension in case of building renovation the component scale includes single building renovation. the district scale may include grouped building renovation. according to borodinecs et al. (2013) the estimated savings can be about 10 % due to grouping development, compared to the component scale renovation. the city scale renovation can include analysis of different building renovation scenarios and future city energy flow planning. as mentioned above, nowadays cross-sector energy action is one of main parts of smart city. as a rule the cross sector action needs to have information and communication technologies. as an example of cross sector action smart electricity grids supporting filling of electric cars can be mentioned. such solution enable charging load of electric vehicles (ev) to be shifted to off-peak periods, thereby significantly reducing both generation and network investment needs and enables customers to schedule charging intelligently (morgan, 2012). 3. designing of smart city urban growth and social changes is a rapid and never ending process nowadays. adapting to the challenges require ways for efficient development of smart city. the models of smart cities should contain a lot of important compounds: social network, economics, community capacity, infrastructure, geographical location of city ecosystem services, political will and history also (collier et al., 2013). the development process must be related to civil protection, risk assessment and evaluation of the post risk strategies. the plans should cover all city communications (heat, gas 56 and water networks and distribution systems, starting from protection of the sources until the end consumer). only the synergy between all compounds can guarantee resilient evolution of intelligent and smart environment. of course, the urban communities must be central component of stakeholders in evolution process. it is essential to provide possibilities of sharing the experience about smart city design and planning between cities and communities. most successful and beneficial projects have to be repeated and recreated widely in europe considering local differences in technical features of infrastructure. in terms of smart cities the most powerful actions are those which directly affect at least these three sectors – energy, ict and transport. dissemination of such projects across the europe will be possible due the fact that the projects have already been approved and implemented in other cities. also energy saving potential can be assessed more accurately and possible shortcomings or limitations considered due to existing experience. it can be called good practice, which in the context of interreg ivc programme is defined as an initiative (e.g. methodologies, projects, processes, techniques) undertaken in one of the programme’s thematic priorities which has already proved successful and which has the potential to be transferred to a different geographic area. proved successful is where the good practice has already provided tangible and measurable results in achieving a specific objective. the good practice examples and detailed descriptions could be found following the link – http://i4c.eu/fichegoodpractices.html?id=234. 4. cross-sector actions in district heating district heating network the joint stock company „rīgas siltums” is the biggest district heating company in latvia and in the baltic countries which is engaged in the production, transmission, distribution and sales of heat, the simultaneous production of heat and generation of power in cogeneration plants, as well as the servicing of district heating networks and systems in riga city. heat is produced in 43 heat sources, including 5 district heating plants (dhp) and 38 automated gas-fired boiler houses (bh). security of district heating and amount of transmission heat losses directly depend upon the technical condition of heat networks and their elements. in the result of the work invested over a long period of time the losses of the heat transmitted to consumers of city of riga have decreased by 667 thous. mwh or 2.45 times in comparison to year 1996/1997 (fig. 3.). during last fiscal year the joint stock company implemented large scale reconstruction of a section of the district heating network main pipeline section m-1 with the total length of 1228 m along brīvības street, where the obsolete pipelines were replaced by new 600 mm preinsulated pipelines, which were installed according to the non-channel technology and equipped with a special alarm system which permits to find the location of a damage in a fast and accurate manner and connected to the automatic remote reading system. co-financing of the european union cohesion fund was used for implementation of this project. fig. 3. heat losses in district heating network [source: annual report, jsc „rīgas siltums”, 2012] heat production from renewable energy sources for the future sustainable development of the district heating system, a few important production development projects have been implemented during the last years, which will allow to achieve considerable savings of fuel and to diversify the fuel, thus improving security of heat supply. the reconstruction of the boiler house at gaileņu street 14 was implemented in fiscal year 2011/2012. the obsolete water heating boilers were replaced and two water heating condensation type boilers with the heating capacity of 1.8 mw were installed. condensation type boilers provide the operational efficiency of boilers which is 7–15 % above that of traditional boilers. the joint stock company, complying with the principle of economic profitability and state support for use of renewable energy resources in energy, plans to expand the use of bio-fuel in heat supply and to reduce heat losses in the district heating transmission; co-funding of the european union funds will be used for these purposes also in future. according to the current trends of the jsc „rīgas siltums” in the upgrading of the heat sources the share of natural gas is to be decreased by increasing the share of biofuel in the fuel balance and the technologies ensuring the highest possible efficiency of the operation of facilities are to be used. the construction of the biofuel fired cogeneration plant of dhp “ziepniekkalns” with heat capacity up to 22 mw and the electrical capacity up to 4 mw was completed in february 2013. the co-financing of the cohesion fund of the european union has been granted for the implementation of this project. it is planned to use biofuel, i.e. wood chips, in this cogeneration plant. the implementation of this project will result in the increase of the share of biofuel in the fuel balance of the jsc „rīgas siltums” by 4.7 %. modernisation of the dhp „zasulauks”, which includes construction of a biofuel fired water heating boiler with the heating capacity of 20 mw which will operate at a high degree of efficiency and automation, without permanent operating personnel was completed in may 2013. the implementation of this project will result in the 57 increase of the share of biofuel in the fuel balance of the jsc „rīgas siltums” by 6.3 %. the implementation of the project „installation of flue gas condensers for biofuel fired boilers at the dhp „vecmīlgrāvis” within the framework “measures for improving efficiency of district heating systems” of the operational program “infrastructure and services” in april 2014 will result in the increase of the share of biofuel in the fuel balance of the jsc „rīgas siltums” by 1 % on average. following the completion of implementation of the above referred projects the share of biofuel utilisation within the fuel balance of the jsc „rīgas siltums” will reach 20.4 % in fiscal year 2013/2014 (fig. 4.). the total energy produced from renewable energy sources since 01.01.1996 until 8.04.2014 is 920463.107 mwh. fig. 4. the increase of the share of biofuel utilisation in heat sources, % [source: annual report, jsc „rīgas siltums”, 2012] heat meters automatic remote reading system in jsc “rigas siltums» riga city. there are four main steps. each building with heat substation and heat meter is equipped with automatic remote reading system, which is used for data reading of heat consumption (in accordance with client need, it can be connected to other data reading, such as cold, hot water or electricity). in addition, there is an antenna placed outside of a building. the data transfer is done by radio waves to special transponders and base stations (not only radio waves, but also gsm or fixed data connection can be used) figure 5. further all data by fixed network is transferred to central data base. from this point, there are two possibilities how the data can be used – web interface, where operators can use the information by connection points or by clients, for example in on-line form all heat meters can be read. second option is related to commercial readings such as invoice preparation. data is collected in oracle data base and then after processing all the invoices can be generated. all data from all 8000 heat meters can be accessed in three hours. fig. 5. automatic remote reading system concept before implementation of this system employees of the heat supply company jsc “rīgas siltums” had to read data from meters on the first day of each month directly in each object and form report on energy consumption. afterwards employees have to enter received readings into the data base. automatic meter remote reading system makes records for all heat meters data in a given time by writing in the current system, excluding human factors on current data quality and minimizing potential errors. reading data at a specific time enables accurate heat data analysis and evaluation of each user’s heat consumption dynamics. this system can be linked to other it systems for technical, analytical or customer services needs. total contract amount was 1.87 million lvl excluding vat, or 2.26 million lvl with vat. the main benefits of implementing this practice are as follows: ▪ operative information on heat loses and operation of heat meters. the potential heat problems can be quickly identified and remedied, improving the quality of services; ▪ less time-consuming billing; ▪ a smaller amount of error due to automatic data entry; ▪ broader customer service options; ▪ optimization of human resources. ▪ possibility to prevent theft of heating unit equipment ▪ transmission of conjugate data such as state of alarm surveillance system of pre-insulated district heating pipes 5. cross-sector actions in transport sector urban growth and social changes nowadays is a rapid process. adapting development and introduction of electric cars and filling station infrastructure in riga was approved by riga city council in the riga city sustainable energy action plan 2010–2020th (seap). with the acceptance of riga city council riga municipal limited liability company “rigas satiksme” has attracted on lease agreement basis five electric cars for use of its technical services, whose daily work is connected to monthly run in average 2000km. because of relatively high cost of introduction of electric cars, it pays off only with relatively high mileage. for a majority of phev (plug-in hybrid electric vehicles) designs and vehicle classes, phevs show a payback period of less 58 than 6 years. however, many of the common components of tco (e.g. maintenance costs, title and registration renewal costs, and salvage value) are not represented in all studies, and payback period is shown to vary between 6 and 12 years (baha m. al-alawi, thomas h. bradley, 2012). in 2013 the state was supported introduction of electric cars and development of filling stations infrastructure (fig.6.) in co-financing from climate change financial instrument. after this riga city council has taken the next step and has sponsored project “electric fast filling station placement schemes for the development of riga” realization. it should be noted that the government is interested in promoting the use of electric cars, improving urban air quality and mitigation of global climate change. fig. 6. scheme of fast charging points distribution in development stage in riga. [source:http://www.latvenergo.lv/portal/page/portal/latvian/ latvenergo/main_page/korp_atbildi/uzlades_punktu_ karte/] selected electronic car type is manufactured by the finnish company “valmet automotive”, designed from norway, and already passed performance tests in the nordic countries. this type of car is well known in europe as several thousands are already sold. these cars are front – wheel driven, with two front seats and 800 litres car trunk. with one charging time the electric car is able to go 120– 150 km, the time spent for one charge is 6–8 hours, and this type of car can develop a speed of 112 km / h. the warranty period is two years or 150 000 km. charging is carried out in the normal grid with capacity 220v. 6. conclusions the smart city development process is a complex process affected by a wide range of different factors. the most important parts are economic, politic and social sectors and the engagement of wide range of stakeholders, which should be dynamic, flexible and ready to changes. currently there are 3414 cities across the europe and eastern partners which already have developed sustainable energy action plan. the overall aim of these plans is to reduce energy demand and to provide the smart use of resources and make the basic contribution in advancement of cities environment, climate and community health. taking into account the modern requirements to city energy consumption and co2 emissions, the standalone energy actions should be integrated at cross sector level. in order to insure urban resilience, all energy actions should be adequately addressed at all city dimensions and scale. only the synergy in these areas guarantees the evolution of intelligent and smart environment. as an example of cross-sector actions is introduction of information and communication technologies in city’s infrastructure providing an opportunity for development of urban resilience. jsc “rigas siltums” takes part in the development of “riga city sustainable energy action plan for smart cities 2014–2020” to significantly exceed the 2020 targets: increase energy efficiency and share of use of renewable energy sources and to further reduction of co2 emissions. district heating network is a subject of constant improvement and in the result of the work invested over a long period of time the losses of the heat transmitted to consumers of city of riga have decreased by 667 thous. mwh or 2.45 times in comparison to year 1996/1997. following the completion of reconstruction of the boiler houses, construction of a biofuel fired water heating boiler, construction of the biofuel fired cogeneration plant, installation of flue gas condensers for biofuel fired boilers at the dhp the share of biofuel utilisation within the fuel balance of the jsc „rīgas siltums” will reach 20.4 % in fiscal year 2013/2014. the total energy produced from renewable energy sources since 01.01.1996 until 8.04.2014 is 920463.107 mwh. the project “heat meters automatic remote reading system” proved to be a successful and reliable solution for the control and accounting of consumed heat, as well as related tasks enabling “online communication” with 8000 individual heating units throughout the riga city. development and introduction of electric cars and filling station infrastructure in riga was one more step on the way to the smart city status. despite a fairly long payback period electric cars are quite beneficial solution for some companies whose activities are related with vehicles’ high mileage within the city as llc “rigas satiksme”. acknowledgment this paper is prepared under eu seventh framework programme (fp7) project “strategies towards energy performance and urban planning” http://www. stepupsmartcities.eu/. authors wish to thank project partners for contribution to project development and support in understanding of smart cities and sustainable energy action plan. references baha m. al-alawi, thomas h. bradley (2012) total cost of ownership, payback, and consumer preference modeling of plug-in hybrid electric vehicles. applied energy, 103, 488– 506. http://dx.doi.org/10.1016/j.apenergy.2012.10.009 borodinecs a., rodriguez-gabriel a., tatarchenko o., and etc. handbook on buildings renovation in central baltic region – isbn – 978-9934-507-39-7 – riga: riga technical university, 2013 – pp. 91. coaffee j. (2008) risk, resilience, and environmentally sustainable cities. energy policy, 36, 4633–4638 http://dx.doi.org/10.1016/j.enpol.2008.09.048 59 collier m. j., nedovic-budic z., aerts j., connop s., foley d., foley k., newport d., mcquaid s., slaev a., verburg p. (2013) transitioning to resilience and sustainability in urban communities. cities, 32, s21–s28. http://dx.doi.org/10.1016/j.cities.2013.03.010 giffinger r. (2007) smart cities: ranking of european mediumsized cities. final report. edited by the centre of regional science, vienna ut; www.smart-cities.eu leichenko r. (2011) climate, change and urban resilience. current opinion in environmental sustainability, 3, 164–168. maria-lluïsa marsal-llacuna, joan colomer-llinàs, joaquim meléndez-frigola (2014) lessons in urban monitoring taken from sustainable and livable cities to better address the smart cities initiative. technological forecasting & social change, pp 12. morgan t. (2012) — discussion paper “smart grids and electric vehicles: made for each other?”2012-02 — © oecd/itf 2012 paolo neirotti, alberto de marco, anna corinna cagliano, giulio mangano , francesco scorrano. current trends in smart city initiatives: some stylised facts. cities, 38 (2014): 25–36. http://dx.doi.org/10.1016/j.cities.2013.12.010 received 2014 04 22 accepted after revision 2014 05 29 aleksandrs zajacs – (mg.sc. ing.) institute of heat, gas and water technology, faculty of civil engineering, riga technical university. main research area: district heating. address: azenes str. 16/20 , lv – 1010, riga, latvia. tel.: +371 29874677 e-mail: aleksandrs.zajacs@rs.lv jurgis zemitis – (mg.sc. ing.) institute of heat, gas and water technology, faculty of civil engineering, riga technical university. main research area: energy efficiency of buildings. address: azenes str. 16/20 , lv – 1010, riga, latvia. tel.: +371 28369940 e-mail: jurgis.zemitis@rtu.lv kristina tihomirova – (dr.sc.ing.) institute of heat, gas and water technology, faculty of civil engineering, riga technical university. main research area: water supply and purification. address: azenes str. 16/20 , lv – 1010, riga, latvia. e-mail: kristina.tihomirova@rtu.lv anatolijs borodinecs – (dr.sc.ing.) institute of heat, gas and water technology, faculty of civil engineering, riga technical university. main research area: energy efficiency of buildings. address: azenes str. 16/20 , lv – 1010, riga, latvia. tel.: +371 26079655 e-mail: anatolijs.borodinecs@rtu.lv journal of sustainable architecture and civil engineering 2014/4/9 74 jsace 4/9 received 2014/09/03 accepted after revision 2014/11/10 journal of sustainable architecture and civil engineering vol. 4 / no. 9 / 2014 pp. 74-82 doi 10.5755/j01.sace.9.4.7913 © kaunas university of technology air permeability tests of masonry structures jolanta šadauskienė, karolis banionis*, valdas paukštys institute of architekture and construction of kaunas university of technology tunelio st. 60, lt 44405 kaunas, lithuania kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania *corresponding author: karolis.banionis@ktu.lt air permeability tests of masonry structures http://dx.doi.org/10.5755/j01.sace.9.4.7913 to date, the assurance of sufficient building‘s air tightness remains a problematic issue, because it is linked not only to the right technology solution selection and quality work, but also to the building envelope air permeability properties. typically, when modelling building energy demand, it is considered that the building envelope is impermeable to air. nevertheless, this claim is unjustified. studies have shown that building materials are porous. however, there is no evidence how air permeability changes through the masonry construction, when it is heterogeneous. therefore, this work is to determine the air permeability of the various types of masonry construction, also assessing the technological masonry aspects, determine the air permeability rate and evaluate the results obtained in the analysis by providing recommendations. keywords: infiltration, blower door, ventilation, air leakage, energy. eu sustainable development approach focuses on efficient consumption of natural and energy resources. the latter is directly related to the construction and building maintenance sector. the increase potential of energy efficiency depends on the use of high-quality structural and insulating materials, which not only reduces heat loss, but also to ensure adequate sealing of the building (pan, 2010), (kalamees et al. 2010) (sfakianakis et al. 2008), (becker , 2010) (kovanen et al. 2009) (matrosov et al. 2007) (feist et al. 2005) (smeds and wall, 2007) (ambrosio et al. 2012). to date, the assurance of sufficient building‘s air tightness remains a problematic issue, because it is linked not only to the right technology solution selection and quality work, but also to the building envelope air permeability properties. when evaluating the physical properties of building envelopes much attention is paid to the heat and humidity carry and the air transport has been completely ignored (hens, 2007; tariku et. al. 2010). typically, when modelling building energy demand, it is considered that the building envelope is impermeable to air. however, this claim is unfounded because the data shows that the building envelope can be permeable to air (haupa et al. 1997, santos and mendes, 2009 salahov et. al., 2011 sedmale et.al. 2009) and this can affect the partition temperature distribution and the total energy demand of the building. studies have shown that building materials are porous, but this depends on the pore size and volume (benazzouk et. al. 2004, hong et al. al. 2012). various materials such as separate masonry bricks, blocks or cubes were studied for air permeability (bentz et al., 2000; quenard et al. 1998 kumaoka, 2000, ohji and fukushima, 2012 studart et. al. 2006), but a complex masonry design air permeability was not introduction 75 journal of sustainable architecture and civil engineering 2014/4/9 sufficiently examined. there is no evidence how air permeability changes through heterogeneous masonry construction. masonry and masonry joints material macrostructure can be different. furthermore, when examining the air permeability of the masonry structure it is important to assess the masonry joints installation technology (en-998-2: a 2003 st 121895674.06:2009). modern masonry technologies can be only applied when installing horizontal masonry joints. vertical non-installation of masonry joints can significantly increase air circulation and thus the total building heat loss. therefore, this work is to determine the air permeability of the various types of masonry construction, also assessing the technological masonry aspects, determine the leakage rate and evaluate the results obtained in the analysis by providing recommendations. methods for the research, a variety of material fragments of masonry structures was selected, and then formed as specimens. there were 10 specimens for each type of construction. masonry construction fragment was inserted into the different size wooden frame. the interface between the timber frame and masonry was sealed with a silicone core. taking into account the recommendations of masonry constructions (st 121895674.06:2009), vertical masonry joints were not installed to masonry structures of calcium silicate, expanded clay (ρ = 650 kg/m3) and ceramic tiles. the technical characteristics of the test specimens can be found in table 1. air permeability measurements of building partitions specimens were determined by the air bandwidth device „ks 3025/45 asd sps touch“ (fig. 1). during the measurement, the measuring chamber was supplied with air, causing the pressure difference between the camera’s internal and external sides, which were separated by specimen. the experiment was designed to determine the amount of air leakage of the specimen, while changing the pressure from 10 to 100 pa according to standard en 13829 “determination of air permeability of buildings”. air leakage rate per specimen area at the tests reference pressure difference was 50 pa. in order to determine the air permeability of 1 m² construction area, specimen air permeability va was calculated using the following formula (1): specimens no. 1 2 3 4 5 6 7 8 material expanded clay expanded clay expanded clay silicate -concrete aerated concrete ceramic silicate -concrete ceramic density, kg/m3 650 883 650 1210 ÷ 1400 575 850 1210 ÷ 1400 850 area of specimen 0,604 0,576 0,604 0,410 0,668 0,752 0,410 0,752 type of masonry joins h hv hv h hv h hv hv width of join, mm ~ 10 ~ 10÷15 ~ 10 ~ 3 ~ 3 ~ 10÷15 ~ 3 ~ 10÷15 hhorizontal masonry joins; v vertical masonry joins where: v 0 – air speed through the specimen in m³/h; s – area of the specimen, m².(1) changing the pressure from 10 to 100 pa according to standard en 13829 “determination of air permeability of buildings”. air leakage rate per specimen area at the tests reference pressure difference was 50 pa. in order to determine the air permeability of 1 m² construction area, specimen air permeability v a was calculated using the following formula (1): ; s o v a v = (1) where: v 0 air speed through the specimen in m³/h; s area of the specimen, m². table 1. technical characteristics of masonry structures specimens specimens no. 1 2 3 4 5 6 7 8 material expanded clay expanded clay expanded clay silicate concrete aerated concrete ceramic silicate concrete ceramic density, kg/m 3 650 883 650 1210 ÷ 1400 575 850 1210 ÷ 1400 850 area of specimen 0,604 0,576 0,604 0,410 0,668 0,752 0,410 0,752 type of masonry joins h hv hv h hv h hv hv width of join, mm ~ 10 ~ 10÷15 ~ 10 ~ 3 ~ 3 ~ 10÷15 ~ 3 ~ 10÷15 hhorizontal masonry joins; v vertical masonry joins fig. 1. the scheme of air permeability determination device fig. 2. the view of masonry structure specimen one-factor anova has been used in order to determine impact of the joints installation technologies on air permeability of masonry structures. dependent variable is a masonry design air permeability v a , which depends on the masonry joints installation factors: the installation of only the horizontal joint h and installing horizontal and vertical joints hv (formula 2). � � = ���, ��� (2) thus, measurements were obtained for air permeability of masonry structures made from calcium silicate, expanded clay (ρ = 650 kg/m 3 ) and ceramic tiles with and without installed vertical masonry joints. for the purposes of onefactor anova, the specimen means of the results obtained were compared with each other. all samples values had n = 10. structured i-th specimen of the j-th observation v a,ij statistical model is quoted as follows (formula 3) � �,�� =�� �� +� �� =�� � +∆�� �� +� �� ; (3) where: v a,ij – i-th masonry construction air permeability average; e ij random error; �� � the total air permeability average of all tested type masonry constructions (total average); ∆�� �,� -the difference of i-th masonry construction air permeability average and total average. in order to determine joint layout and filling influence on air permeability of the masonry structure, the following hypotheses were tested (formula 4): movable horizontal plane movable vertical plane specimen air flow air flow sensors: 0 – 50 m³; 50 – 300 m³ table 1 technical characteristics of masonry structures specimens journal of sustainable architecture and civil engineering 2014/4/9 76 one-factor anova has been used in order to determine impact of the joints installation technologies on air permeability of masonry structures. dependent variable is a masonry design air permeability v a , which depends on the masonry joints installation factors: the installation of only the horizontal joint h and installing horizontal and vertical joints hv (formula 2). changing the pressure from 10 to 100 pa according to standard en 13829 “determination of air permeability of buildings”. air leakage rate per specimen area at the tests reference pressure difference was 50 pa. in order to determine the air permeability of 1 m² construction area, specimen air permeability v a was calculated using the following formula (1): ; s o v a v = (1) where: v 0 air speed through the specimen in m³/h; s area of the specimen, m². table 1. technical characteristics of masonry structures specimens specimens no. 1 2 3 4 5 6 7 8 material expanded clay expanded clay expanded clay silicate concrete aerated concrete ceramic silicate concrete ceramic density, kg/m 3 650 883 650 1210 ÷ 1400 575 850 1210 ÷ 1400 850 area of specimen 0,604 0,576 0,604 0,410 0,668 0,752 0,410 0,752 type of masonry joins h hv hv h hv h hv hv width of join, mm ~ 10 ~ 10÷15 ~ 10 ~ 3 ~ 3 ~ 10÷15 ~ 3 ~ 10÷15 hhorizontal masonry joins; v vertical masonry joins fig. 1. the scheme of air permeability determination device fig. 2. the view of masonry structure specimen one-factor anova has been used in order to determine impact of the joints installation technologies on air permeability of masonry structures. dependent variable is a masonry design air permeability v a , which depends on the masonry joints installation factors: the installation of only the horizontal joint h and installing horizontal and vertical joints hv (formula 2). (2) thus, measurements were obtained for air permeability of masonry structures made from calcium silicate, expanded clay (ρ = 650 kg/m 3 ) and ceramic tiles with and without installed vertical masonry joints. for the purposes of onefactor anova, the specimen means of the results obtained were compared with each other. all samples values had n = 10. structured i-th specimen of the j-th observation v a,ij statistical model is quoted as follows (formula 3) (3) where: v a,ij – i-th masonry construction air permeability average; e ij random error; the total air permeability average of all tested type masonry constructions (total average); -the difference of i-th masonry construction air permeability average and total average. in order to determine joint layout and filling influence on air permeability of the masonry structure, the following hypotheses were tested (formula 4): movable horizontal plane movable vertical plane specimen air flow air flow sensors: 0 – 50 m³; 50 – 300 m³ fig. 1 the scheme of air permeability determination device thus, measurements were obtained for air permeability of masonry structures made from calcium silicate, expanded clay (ρ = 650 kg/m3) and ceramic tiles with and without installed vertical masonry joints. for the (2) changing the pressure from 10 to 100 pa according to standard en 13829 “determination of air permeability of buildings”. air leakage rate per specimen area at the tests reference pressure difference was 50 pa. in order to determine the air permeability of 1 m² construction area, specimen air permeability v a was calculated using the following formula (1): ; s o v a v = (1) where: v 0 air speed through the specimen in m³/h; s area of the specimen, m². table 1. technical characteristics of masonry structures specimens specimens no. 1 2 3 4 5 6 7 8 material expanded clay expanded clay expanded clay silicate concrete aerated concrete ceramic silicate concrete ceramic density, kg/m 3 650 883 650 1210 ÷ 1400 575 850 1210 ÷ 1400 850 area of specimen 0,604 0,576 0,604 0,410 0,668 0,752 0,410 0,752 type of masonry joins h hv hv h hv h hv hv width of join, mm ~ 10 ~ 10÷15 ~ 10 ~ 3 ~ 3 ~ 10÷15 ~ 3 ~ 10÷15 hhorizontal masonry joins; v vertical masonry joins fig. 1. the scheme of air permeability determination device fig. 2. the view of masonry structure specimen one-factor anova has been used in order to determine impact of the joints installation technologies on air permeability of masonry structures. dependent variable is a masonry design air permeability v a , which depends on the masonry joints installation factors: the installation of only the horizontal joint h and installing horizontal and vertical joints hv (formula 2). � � = ���, ��� (2) thus, measurements were obtained for air permeability of masonry structures made from calcium silicate, expanded clay (ρ = 650 kg/m 3 ) and ceramic tiles with and without installed vertical masonry joints. for the purposes of onefactor anova, the specimen means of the results obtained were compared with each other. all samples values had n = 10. structured i-th specimen of the j-th observation v a,ij statistical model is quoted as follows (formula 3) � �,�� =�� �� +� �� =�� � +∆�� �� +� �� ; (3) where: v a,ij – i-th masonry construction air permeability average; e ij random error; �� � the total air permeability average of all tested type masonry constructions (total average); ∆�� �,� -the difference of i-th masonry construction air permeability average and total average. in order to determine joint layout and filling influence on air permeability of the masonry structure, the following hypotheses were tested (formula 4): movable horizontal plane movable vertical plane specimen air flow air flow sensors: 0 – 50 m³; 50 – 300 m³ in order to determine joint layout and filling influence on air permeability of the masonry structure, the following hypotheses were tested (formula 4): the null hypothesis h 0 states that the vertical joints of masonry installation do not affect the air permeability of the masonry structure. h 1 hypothesis states that at least two specimen averages are different. the following formula is used to verify both assumptions (formula 5): where: v a,ij – i-th masonry construction air permeability average; e ij – random error; (3) changing the pressure from 10 to 100 pa according to standard en 13829 “determination of air permeability of buildings”. air leakage rate per specimen area at the tests reference pressure difference was 50 pa. in order to determine the air permeability of 1 m² construction area, specimen air permeability v a was calculated using the following formula (1): ; s o v a v = (1) where: v 0 air speed through the specimen in m³/h; s area of the specimen, m². table 1. technical characteristics of masonry structures specimens specimens no. 1 2 3 4 5 6 7 8 material expanded clay expanded clay expanded clay silicate concrete aerated concrete ceramic silicate concrete ceramic density, kg/m 3 650 883 650 1210 ÷ 1400 575 850 1210 ÷ 1400 850 area of specimen 0,604 0,576 0,604 0,410 0,668 0,752 0,410 0,752 type of masonry joins h hv hv h hv h hv hv width of join, mm ~ 10 ~ 10÷15 ~ 10 ~ 3 ~ 3 ~ 10÷15 ~ 3 ~ 10÷15 hhorizontal masonry joins; v vertical masonry joins fig. 1. the scheme of air permeability determination device fig. 2. the view of masonry structure specimen one-factor anova has been used in order to determine impact of the joints installation technologies on air permeability of masonry structures. dependent variable is a masonry design air permeability v a , which depends on the masonry joints installation factors: the installation of only the horizontal joint h and installing horizontal and vertical joints hv (formula 2). � � = ���, ��� (2) thus, measurements were obtained for air permeability of masonry structures made from calcium silicate, expanded clay (ρ = 650 kg/m 3 ) and ceramic tiles with and without installed vertical masonry joints. for the purposes of onefactor anova, the specimen means of the results obtained were compared with each other. all samples values had n = 10. structured i-th specimen of the j-th observation v a,ij statistical model is quoted as follows (formula 3) � �,�� =�� �� +� �� =�� � +∆�� �� +� �� ; (3) where: v a,ij – i-th masonry construction air permeability average; e ij random error; �� � the total air permeability average of all tested type masonry constructions (total average); ∆�� �,� -the difference of i-th masonry construction air permeability average and total average. in order to determine joint layout and filling influence on air permeability of the masonry structure, the following hypotheses were tested (formula 4): movable horizontal plane movable vertical plane specimen air flow air flow sensors: 0 – 50 m³; 50 – 300 m³ (4) purposes of one-factor anova, the specimen means of the results obtained were compared with each other. all samples values had n = 10. structured i-th specimen of the j-th observation v a,ij statistical model is quoted as follows (formula 3) � � : �� �,� = �� �,� = ⋯ = �� � ; � � = �� �,� ≠ �� �,� (4) the null hypothesis h 0 states that the vertical joints of masonry installation do not affect the air permeability of the masonry structure. h 1 hypothesis states that at least two specimen averages are different. the following formula is used to verify both assumptions (formula 5): � = ∑ � � �� �,� − �� � ��� ��� � − 1 ∙ � − � ∑ ∑ �� �,�� − �� �,� ���� ��� � ��� (5) where: f – test statistic; n – statistical array. the level of significance was α = 0.05. this size is chosen so that the first type of error equal to α. the probability that the criterion of f statistics is not less than the observed realization t, expressed in pvalue of p = p (t ≥ t), where h 0 is correct the hypothesis h 0 is rejected if the p-value < α (h 1 is favoured, not all means are equal). otherwise, h 0 is favoured (p-value ≥ α) . in order to determine which of masonry structures air permeability specimen averages are significantly different, “bonferroni correction post hoc” test was used, based on the so-called q stjudent distance statistic were applied. averages iav , _ and ja v , are statistically significantly different, according to 6, 7, 8 formulas: ��� �,� − �� �,� � > ���; (6) ��� = � ��� � ����� − �, ��; (7) ��� = ∑ ∑ �� �,�� − �� � ���� ��� � ��� � − � (8) where: tsd – “bonferroni correction post hoc” test; msw – unbiased (inner) estimator of dispersion; q a – the critical value of q statistic’s α level; n the size of the sample. 3. results in order to determine the amount of air flow through the fragments of masonry construction, air permeability test was carried out. average air flow values are given in table 2. from the results shown in table 2, it can be observed that the greatest air flow occurred in specimens made from expanded clay blocks (no. 1 and no. 3), at 50 pa pressure difference an average air flow was 44.5 m³/h and 56.9 m³/h respectively. the density of the specimens was the same ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had horizontal masonry joints installed, specimens no. 3 had both horizontal and vertical masonry joints installed. masonry installation technology has resulted in different air flow performance. if vertical masonry joints are not installed, air flow through the wall structure increases. table 2. average results of air flow through specimens δp, pa specimen no. 1 2 3 4 5 6 7 8 air flow v 0t , m 3 /h 10 14,7 2,4 11,7 0,4 0,1 10,5 0,4 0,5 20 26,1 5,5 21,6 1,3 0,3 17,0 1,2 1,5 30 37,9 8,1 29,0 1,7 0,5 20,6 1,7 2,0 40 47,0 10,7 38,1 2,1 0,6 25,2 2,1 2,3 50 56,9 13,9 44,5 2,3 0,8 27,3 2,3 2,6 60 62,6 16,5 50,0 2,6 1,0 31,0 2,6 2,9 70 67,8 19,3 56,5 2,8 1,3 34,7 2,8 3,1 80 76,0 21,2 58,9 3,0 1,4 38,1 3,0 3,7 90 82,3 24,3 65,1 3,1 1,5 40,5 3,1 4,0 101 90,1 26,3 67,3 3,7 1,6 43,1 3,7 4,7 minimum air flow through the masonry construction is observed in those specimen made from aerated concrete blocks (no. 5), with an average air flow of 0.8 m³/h at 50 pa pressure difference. these brick structures were sealed with mortar joints both vertically and horizontally. also measurements showed that the average air flow rate at 50 pa pressure difference through the wall structure of calcium silicate blocks (specimen no. 4) is 2.3 m³/h, and the ceramic tiles stone (specimen no. 6) – 27.3 m³/h. these brick structures were equipped with only horizontal masonry joints. all measured masonry structures specimens’ air permeability, changing the pressure difference, is shown in figure 3. fig. 3. air permeability measurement results of masonry structures specimens by changing pressure difference the results in figure 3 shows that least airtight specimens at a 50 pa pressure difference were masonry structure of expanded clay blocks (no. 1, no. 2 and no. 3) with an air permeability of 98.7 m³/h·m 2 , 24.1 m³/h ·m 2 and 73.6 m³/h· m 2 . the most airtight specimens were of aerated concrete blocks (no.5, v a = 1,2 m³/h·m²), silicate masonry blocks (no.7, v a = 5,5 m³/h·m² and no.4, v a = 4,6 m³/h·m²) and ceramic blocks (no.8, v a = 3,5 m³/h·m²). the analysis of masonry installation technologies on the specimen air permeability suggested that the air flow depends on the arrangement of the masonry joints and 0 20 40 60 80 100 120 140 160 180 0 50 100 a i r p e r m e a b i l i t y v a , m 3 / h m 2 the pressure difference ∆p, pa 1 2 3 4 5 8 7 6 where: f – test statistic; n – statistical array. (5) � � : �� �,� = �� �,� = ⋯ = �� � ; � � = �� �,� ≠ �� �,� (4) the null hypothesis h 0 states that the vertical joints of masonry installation do not affect the air permeability of the masonry structure. h 1 hypothesis states that at least two specimen averages are different. the following formula is used to verify both assumptions (formula 5): � = ∑ � � �� �,� − �� � ��� ��� � − 1 ∙ � − � ∑ ∑ �� �,�� − �� �,� ���� ��� � ��� (5) where: f – test statistic; n – statistical array. the level of significance was α = 0.05. this size is chosen so that the first type of error equal to α. the probability that the criterion of f statistics is not less than the observed realization t, expressed in pvalue of p = p (t ≥ t), where h 0 is correct the hypothesis h 0 is rejected if the p-value < α (h 1 is favoured, not all means are equal). otherwise, h 0 is favoured (p-value ≥ α) . in order to determine which of masonry structures air permeability specimen averages are significantly different, “bonferroni correction post hoc” test was used, based on the so-called q stjudent distance statistic were applied. averages iav , _ and ja v , are statistically significantly different, according to 6, 7, 8 formulas: ��� �,� − �� �,� � > ���; (6) ��� = � ��� � ����� − �, ��; (7) ��� = ∑ ∑ �� �,�� − �� � ���� ��� � ��� � − � (8) where: tsd – “bonferroni correction post hoc” test; msw – unbiased (inner) estimator of dispersion; q a – the critical value of q statistic’s α level; n the size of the sample. 3. results in order to determine the amount of air flow through the fragments of masonry construction, air permeability test was carried out. average air flow values are given in table 2. from the results shown in table 2, it can be observed that the greatest air flow occurred in specimens made from expanded clay blocks (no. 1 and no. 3), at 50 pa pressure difference an average air flow was 44.5 m³/h and 56.9 m³/h respectively. the density of the specimens was the same ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had horizontal masonry joints installed, specimens no. 3 had both horizontal and vertical masonry joints installed. masonry installation technology has resulted in different air flow performance. if vertical masonry joints are not installed, air flow through the wall structure increases. table 2. average results of air flow through specimens δp, pa specimen no. 1 2 3 4 5 6 7 8 air flow v 0t , m 3 /h 10 14,7 2,4 11,7 0,4 0,1 10,5 0,4 0,5 20 26,1 5,5 21,6 1,3 0,3 17,0 1,2 1,5 30 37,9 8,1 29,0 1,7 0,5 20,6 1,7 2,0 40 47,0 10,7 38,1 2,1 0,6 25,2 2,1 2,3 50 56,9 13,9 44,5 2,3 0,8 27,3 2,3 2,6 60 62,6 16,5 50,0 2,6 1,0 31,0 2,6 2,9 70 67,8 19,3 56,5 2,8 1,3 34,7 2,8 3,1 80 76,0 21,2 58,9 3,0 1,4 38,1 3,0 3,7 90 82,3 24,3 65,1 3,1 1,5 40,5 3,1 4,0 101 90,1 26,3 67,3 3,7 1,6 43,1 3,7 4,7 minimum air flow through the masonry construction is observed in those specimen made from aerated concrete blocks (no. 5), with an average air flow of 0.8 m³/h at 50 pa pressure difference. these brick structures were sealed with mortar joints both vertically and horizontally. also measurements showed that the average air flow rate at 50 pa pressure difference through the wall structure of calcium silicate blocks (specimen no. 4) is 2.3 m³/h, and the ceramic tiles stone (specimen no. 6) – 27.3 m³/h. these brick structures were equipped with only horizontal masonry joints. all measured masonry structures specimens’ air permeability, changing the pressure difference, is shown in figure 3. fig. 3. air permeability measurement results of masonry structures specimens by changing pressure difference the results in figure 3 shows that least airtight specimens at a 50 pa pressure difference were masonry structure of expanded clay blocks (no. 1, no. 2 and no. 3) with an air permeability of 98.7 m³/h·m 2 , 24.1 m³/h ·m 2 and 73.6 m³/h· m 2 . the most airtight specimens were of aerated concrete blocks (no.5, v a = 1,2 m³/h·m²), silicate masonry blocks (no.7, v a = 5,5 m³/h·m² and no.4, v a = 4,6 m³/h·m²) and ceramic blocks (no.8, v a = 3,5 m³/h·m²). the analysis of masonry installation technologies on the specimen air permeability suggested that the air flow depends on the arrangement of the masonry joints and 0 20 40 60 80 100 120 140 160 180 0 50 100 a i r p e r m e a b i l i t y v a , m 3 / h m 2 the pressure difference ∆p, pa 1 2 3 4 5 8 7 6 � � : �� �,� = �� �,� = ⋯ = �� � ; � � = �� �,� ≠ �� �,� (4) the null hypothesis h 0 states that the vertical joints of masonry installation do not affect the air permeability of the masonry structure. h 1 hypothesis states that at least two specimen averages are different. the following formula is used to verify both assumptions (formula 5): � = ∑ � � �� �,� − �� � ��� ��� � − 1 ∙ � − � ∑ ∑ �� �,�� − �� �,� ���� ��� � ��� (5) where: f – test statistic; n – statistical array. the level of significance was α = 0.05. this size is chosen so that the first type of error equal to α. the probability that the criterion of f statistics is not less than the observed realization t, expressed in pvalue of p = p (t ≥ t), where h 0 is correct the hypothesis h 0 is rejected if the p-value < α (h 1 is favoured, not all means are equal). otherwise, h 0 is favoured (p-value ≥ α) . in order to determine which of masonry structures air permeability specimen averages are significantly different, “bonferroni correction post hoc” test was used, based on the so-called q stjudent distance statistic were applied. averages iav , _ and ja v , are statistically significantly different, according to 6, 7, 8 formulas: ��� �,� − �� �,� � > ���; (6) ��� = � ��� � ����� − �, ��; (7) ��� = ∑ ∑ �� �,�� − �� � ���� ��� � ��� � − � (8) where: tsd – “bonferroni correction post hoc” test; msw – unbiased (inner) estimator of dispersion; q a – the critical value of q statistic’s α level; n the size of the sample. 3. results in order to determine the amount of air flow through the fragments of masonry construction, air permeability test was carried out. average air flow values are given in table 2. from the results shown in table 2, it can be observed that the greatest air flow occurred in specimens made from expanded clay blocks (no. 1 and no. 3), at 50 pa pressure difference an average air flow was 44.5 m³/h and 56.9 m³/h respectively. the density of the specimens was the same ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had horizontal masonry joints installed, specimens no. 3 had both horizontal and vertical masonry joints installed. masonry installation technology has resulted in different air flow performance. if vertical masonry joints are not installed, air flow through the wall structure increases. table 2. average results of air flow through specimens δp, pa specimen no. 1 2 3 4 5 6 7 8 air flow v 0t , m 3 /h 10 14,7 2,4 11,7 0,4 0,1 10,5 0,4 0,5 20 26,1 5,5 21,6 1,3 0,3 17,0 1,2 1,5 30 37,9 8,1 29,0 1,7 0,5 20,6 1,7 2,0 40 47,0 10,7 38,1 2,1 0,6 25,2 2,1 2,3 50 56,9 13,9 44,5 2,3 0,8 27,3 2,3 2,6 60 62,6 16,5 50,0 2,6 1,0 31,0 2,6 2,9 70 67,8 19,3 56,5 2,8 1,3 34,7 2,8 3,1 80 76,0 21,2 58,9 3,0 1,4 38,1 3,0 3,7 90 82,3 24,3 65,1 3,1 1,5 40,5 3,1 4,0 101 90,1 26,3 67,3 3,7 1,6 43,1 3,7 4,7 minimum air flow through the masonry construction is observed in those specimen made from aerated concrete blocks (no. 5), with an average air flow of 0.8 m³/h at 50 pa pressure difference. these brick structures were sealed with mortar joints both vertically and horizontally. also measurements showed that the average air flow rate at 50 pa pressure difference through the wall structure of calcium silicate blocks (specimen no. 4) is 2.3 m³/h, and the ceramic tiles stone (specimen no. 6) – 27.3 m³/h. these brick structures were equipped with only horizontal masonry joints. all measured masonry structures specimens’ air permeability, changing the pressure difference, is shown in figure 3. fig. 3. air permeability measurement results of masonry structures specimens by changing pressure difference the results in figure 3 shows that least airtight specimens at a 50 pa pressure difference were masonry structure of expanded clay blocks (no. 1, no. 2 and no. 3) with an air permeability of 98.7 m³/h·m 2 , 24.1 m³/h ·m 2 and 73.6 m³/h· m 2 . the most airtight specimens were of aerated concrete blocks (no.5, v a = 1,2 m³/h·m²), silicate masonry blocks (no.7, v a = 5,5 m³/h·m² and no.4, v a = 4,6 m³/h·m²) and ceramic blocks (no.8, v a = 3,5 m³/h·m²). the analysis of masonry installation technologies on the specimen air permeability suggested that the air flow depends on the arrangement of the masonry joints and 0 20 40 60 80 100 120 140 160 180 0 50 100 a i r p e r m e a b i l i t y v a , m 3 / h m 2 the pressure difference ∆p, pa 1 2 3 4 5 8 7 6 changing the pressure from 10 to 100 pa according to standard en 13829 “determination of air permeability of buildings”. air leakage rate per specimen area at the tests reference pressure difference was 50 pa. in order to determine the air permeability of 1 m² construction area, specimen air permeability v a was calculated using the following formula (1): ; s o v a v = (1) where: v 0 air speed through the specimen in m³/h; s area of the specimen, m². table 1. technical characteristics of masonry structures specimens specimens no. 1 2 3 4 5 6 7 8 material expanded clay expanded clay expanded clay silicate concrete aerated concrete ceramic silicate concrete ceramic density, kg/m 3 650 883 650 1210 ÷ 1400 575 850 1210 ÷ 1400 850 area of specimen 0,604 0,576 0,604 0,410 0,668 0,752 0,410 0,752 type of masonry joins h hv hv h hv h hv hv width of join, mm ~ 10 ~ 10÷15 ~ 10 ~ 3 ~ 3 ~ 10÷15 ~ 3 ~ 10÷15 hhorizontal masonry joins; v vertical masonry joins fig. 1. the scheme of air permeability determination device fig. 2. the view of masonry structure specimen one-factor anova has been used in order to determine impact of the joints installation technologies on air permeability of masonry structures. dependent variable is a masonry design air permeability v a , which depends on the masonry joints installation factors: the installation of only the horizontal joint h and installing horizontal and vertical joints hv (formula 2). � � = ���, ��� (2) thus, measurements were obtained for air permeability of masonry structures made from calcium silicate, expanded clay (ρ = 650 kg/m 3 ) and ceramic tiles with and without installed vertical masonry joints. for the purposes of onefactor anova, the specimen means of the results obtained were compared with each other. all samples values had n = 10. structured i-th specimen of the j-th observation v a,ij statistical model is quoted as follows (formula 3) � �,�� =�� �� +� �� =�� � +∆�� �� +� �� ; (3) where: v a,ij – i-th masonry construction air permeability average; e ij random error; �� � the total air permeability average of all tested type masonry constructions (total average); ∆�� �,� -the difference of i-th masonry construction air permeability average and total average. in order to determine joint layout and filling influence on air permeability of the masonry structure, the following hypotheses were tested (formula 4): movable horizontal plane movable vertical plane specimen air flow air flow sensors: 0 – 50 m³; 50 – 300 m³ – the total air permeability average of all tested type masonry constructions (total average); changing the pressure from 10 to 100 pa according to standard en 13829 “determination of air permeability of buildings”. air leakage rate per specimen area at the tests reference pressure difference was 50 pa. in order to determine the air permeability of 1 m² construction area, specimen air permeability v a was calculated using the following formula (1): ; s o v a v = (1) where: v 0 air speed through the specimen in m³/h; s area of the specimen, m². table 1. technical characteristics of masonry structures specimens specimens no. 1 2 3 4 5 6 7 8 material expanded clay expanded clay expanded clay silicate concrete aerated concrete ceramic silicate concrete ceramic density, kg/m 3 650 883 650 1210 ÷ 1400 575 850 1210 ÷ 1400 850 area of specimen 0,604 0,576 0,604 0,410 0,668 0,752 0,410 0,752 type of masonry joins h hv hv h hv h hv hv width of join, mm ~ 10 ~ 10÷15 ~ 10 ~ 3 ~ 3 ~ 10÷15 ~ 3 ~ 10÷15 hhorizontal masonry joins; v vertical masonry joins fig. 1. the scheme of air permeability determination device fig. 2. the view of masonry structure specimen one-factor anova has been used in order to determine impact of the joints installation technologies on air permeability of masonry structures. dependent variable is a masonry design air permeability v a , which depends on the masonry joints installation factors: the installation of only the horizontal joint h and installing horizontal and vertical joints hv (formula 2). � � = ���, ��� (2) thus, measurements were obtained for air permeability of masonry structures made from calcium silicate, expanded clay (ρ = 650 kg/m 3 ) and ceramic tiles with and without installed vertical masonry joints. for the purposes of onefactor anova, the specimen means of the results obtained were compared with each other. all samples values had n = 10. structured i-th specimen of the j-th observation v a,ij statistical model is quoted as follows (formula 3) � �,�� =�� �� +� �� =�� � +∆�� �� +� �� ; (3) where: v a,ij – i-th masonry construction air permeability average; e ij random error; �� � the total air permeability average of all tested type masonry constructions (total average); ∆�� �,� -the difference of i-th masonry construction air permeability average and total average. in order to determine joint layout and filling influence on air permeability of the masonry structure, the following hypotheses were tested (formula 4): movable horizontal plane movable vertical plane specimen air flow air flow sensors: 0 – 50 m³; 50 – 300 m³ – the difference of i-th masonry construction air permeability average and total average. 77 journal of sustainable architecture and civil engineering 2014/4/9 the level of significance was α = 0.05. this size is chosen so that the first type of error equal to α. the probability that the criterion of f statistics is not less than the observed realization t, expressed in p value of p = p (t ≥ t), where h 0 is correct the hypothesis h 0 is rejected if the p-value < α(h 1 is favoured, not all means are equal). otherwise, h 0 is favoured (p-value ≥ α) . in order to determine which of masonry structures air permeability specimen averages are significantly different, changing the pressure from 10 to 100 pa according to standard en 13829 “determination of air permeability of buildings”. air leakage rate per specimen area at the tests reference pressure difference was 50 pa. in order to determine the air permeability of 1 m² construction area, specimen air permeability v a was calculated using the following formula (1): ; s o v a v = (1) where: v 0 air speed through the specimen in m³/h; s area of the specimen, m². table 1. technical characteristics of masonry structures specimens specimens no. 1 2 3 4 5 6 7 8 material expanded clay expanded clay expanded clay silicate concrete aerated concrete ceramic silicate concrete ceramic density, kg/m 3 650 883 650 1210 ÷ 1400 575 850 1210 ÷ 1400 850 area of specimen 0,604 0,576 0,604 0,410 0,668 0,752 0,410 0,752 type of masonry joins h hv hv h hv h hv hv width of join, mm ~ 10 ~ 10÷15 ~ 10 ~ 3 ~ 3 ~ 10÷15 ~ 3 ~ 10÷15 hhorizontal masonry joins; v vertical masonry joins fig. 1. the scheme of air permeability determination device fig. 2. the view of masonry structure specimen one-factor anova has been used in order to determine impact of the joints installation technologies on air permeability of masonry structures. dependent variable is a masonry design air permeability v a , which depends on the masonry joints installation factors: the installation of only the horizontal joint h and installing horizontal and vertical joints hv (formula 2). (2) thus, measurements were obtained for air permeability of masonry structures made from calcium silicate, expanded clay (ρ = 650 kg/m 3 ) and ceramic tiles with and without installed vertical masonry joints. for the purposes of onefactor anova, the specimen means of the results obtained were compared with each other. all samples values had n = 10. structured i-th specimen of the j-th observation v a,ij statistical model is quoted as follows (formula 3) (3) where: v a,ij – i-th masonry construction air permeability average; e ij random error; the total air permeability average of all tested type masonry constructions (total average); -the difference of i-th masonry construction air permeability average and total average. in order to determine joint layout and filling influence on air permeability of the masonry structure, the following hypotheses were tested (formula 4): movable horizontal plane movable vertical plane specimen air flow air flow sensors: 0 – 50 m³; 50 – 300 m³ fig. 2 the view of masonry structure specimen “bonferroni correction post hoc” test was used, based on the so-called q stjudent distance statistic were applied. averages iav , _ and jav , are statistically significantly different, according to 6, 7, 8 formulas: where: tsd – “bonferroni correction post hoc” test; msw – unbiased (inner) estimator of dispersion; q a – the critical value of q statistic’s α level; n the size of the sample. (6) (7) (8) � � : �� �,� = �� �,� = ⋯ = �� � ; � � = �� �,� ≠ �� �,� (4) the null hypothesis h 0 states that the vertical joints of masonry installation do not affect the air permeability of the masonry structure. h 1 hypothesis states that at least two specimen averages are different. the following formula is used to verify both assumptions (formula 5): � = ∑ � � �� �,� − �� � ��� ��� � − 1 ∙ � − � ∑ ∑ �� �,�� − �� �,� ���� ��� � ��� (5) where: f – test statistic; n – statistical array. the level of significance was α = 0.05. this size is chosen so that the first type of error equal to α. the probability that the criterion of f statistics is not less than the observed realization t, expressed in pvalue of p = p (t ≥ t), where h 0 is correct the hypothesis h 0 is rejected if the p-value < α (h 1 is favoured, not all means are equal). otherwise, h 0 is favoured (p-value ≥ α) . in order to determine which of masonry structures air permeability specimen averages are significantly different, “bonferroni correction post hoc” test was used, based on the so-called q stjudent distance statistic were applied. averages iav , _ and ja v , are statistically significantly different, according to 6, 7, 8 formulas: ��� �,� − �� �,� � > ���; (6) ��� = � ��� � ����� − �, ��; (7) ��� = ∑ ∑ �� �,�� − �� � ���� ��� � ��� � − � (8) where: tsd – “bonferroni correction post hoc” test; msw – unbiased (inner) estimator of dispersion; q a – the critical value of q statistic’s α level; n the size of the sample. 3. results in order to determine the amount of air flow through the fragments of masonry construction, air permeability test was carried out. average air flow values are given in table 2. from the results shown in table 2, it can be observed that the greatest air flow occurred in specimens made from expanded clay blocks (no. 1 and no. 3), at 50 pa pressure difference an average air flow was 44.5 m³/h and 56.9 m³/h respectively. the density of the specimens was the same ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had horizontal masonry joints installed, specimens no. 3 had both horizontal and vertical masonry joints installed. masonry installation technology has resulted in different air flow performance. if vertical masonry joints are not installed, air flow through the wall structure increases. table 2. average results of air flow through specimens δp, pa specimen no. 1 2 3 4 5 6 7 8 air flow v 0t , m 3 /h 10 14,7 2,4 11,7 0,4 0,1 10,5 0,4 0,5 20 26,1 5,5 21,6 1,3 0,3 17,0 1,2 1,5 30 37,9 8,1 29,0 1,7 0,5 20,6 1,7 2,0 40 47,0 10,7 38,1 2,1 0,6 25,2 2,1 2,3 50 56,9 13,9 44,5 2,3 0,8 27,3 2,3 2,6 60 62,6 16,5 50,0 2,6 1,0 31,0 2,6 2,9 70 67,8 19,3 56,5 2,8 1,3 34,7 2,8 3,1 80 76,0 21,2 58,9 3,0 1,4 38,1 3,0 3,7 90 82,3 24,3 65,1 3,1 1,5 40,5 3,1 4,0 101 90,1 26,3 67,3 3,7 1,6 43,1 3,7 4,7 minimum air flow through the masonry construction is observed in those specimen made from aerated concrete blocks (no. 5), with an average air flow of 0.8 m³/h at 50 pa pressure difference. these brick structures were sealed with mortar joints both vertically and horizontally. also measurements showed that the average air flow rate at 50 pa pressure difference through the wall structure of calcium silicate blocks (specimen no. 4) is 2.3 m³/h, and the ceramic tiles stone (specimen no. 6) – 27.3 m³/h. these brick structures were equipped with only horizontal masonry joints. all measured masonry structures specimens’ air permeability, changing the pressure difference, is shown in figure 3. fig. 3. air permeability measurement results of masonry structures specimens by changing pressure difference the results in figure 3 shows that least airtight specimens at a 50 pa pressure difference were masonry structure of expanded clay blocks (no. 1, no. 2 and no. 3) with an air permeability of 98.7 m³/h·m 2 , 24.1 m³/h ·m 2 and 73.6 m³/h· m 2 . the most airtight specimens were of aerated concrete blocks (no.5, v a = 1,2 m³/h·m²), silicate masonry blocks (no.7, v a = 5,5 m³/h·m² and no.4, v a = 4,6 m³/h·m²) and ceramic blocks (no.8, v a = 3,5 m³/h·m²). the analysis of masonry installation technologies on the specimen air permeability suggested that the air flow depends on the arrangement of the masonry joints and 0 20 40 60 80 100 120 140 160 180 0 50 100 a i r p e r m e a b i l i t y v a , m 3 / h m 2 the pressure difference ∆p, pa 1 2 3 4 5 8 7 6 � � : �� �,� = �� �,� = ⋯ = �� � ; � � = �� �,� ≠ �� �,� (4) the null hypothesis h 0 states that the vertical joints of masonry installation do not affect the air permeability of the masonry structure. h 1 hypothesis states that at least two specimen averages are different. the following formula is used to verify both assumptions (formula 5): � = ∑ � � �� �,� − �� � ��� ��� � − 1 ∙ � − � ∑ ∑ �� �,�� − �� �,� ���� ��� � ��� (5) where: f – test statistic; n – statistical array. the level of significance was α = 0.05. this size is chosen so that the first type of error equal to α. the probability that the criterion of f statistics is not less than the observed realization t, expressed in pvalue of p = p (t ≥ t), where h 0 is correct the hypothesis h 0 is rejected if the p-value < α (h 1 is favoured, not all means are equal). otherwise, h 0 is favoured (p-value ≥ α) . in order to determine which of masonry structures air permeability specimen averages are significantly different, “bonferroni correction post hoc” test was used, based on the so-called q stjudent distance statistic were applied. averages iav , _ and ja v , are statistically significantly different, according to 6, 7, 8 formulas: ��� �,� − �� �,� � > ���; (6) ��� = � ��� � ����� − �, ��; (7) ��� = ∑ ∑ �� �,�� − �� � ���� ��� � ��� � − � (8) where: tsd – “bonferroni correction post hoc” test; msw – unbiased (inner) estimator of dispersion; q a – the critical value of q statistic’s α level; n the size of the sample. 3. results in order to determine the amount of air flow through the fragments of masonry construction, air permeability test was carried out. average air flow values are given in table 2. from the results shown in table 2, it can be observed that the greatest air flow occurred in specimens made from expanded clay blocks (no. 1 and no. 3), at 50 pa pressure difference an average air flow was 44.5 m³/h and 56.9 m³/h respectively. the density of the specimens was the same ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had horizontal masonry joints installed, specimens no. 3 had both horizontal and vertical masonry joints installed. masonry installation technology has resulted in different air flow performance. if vertical masonry joints are not installed, air flow through the wall structure increases. table 2. average results of air flow through specimens δp, pa specimen no. 1 2 3 4 5 6 7 8 air flow v 0t , m 3 /h 10 14,7 2,4 11,7 0,4 0,1 10,5 0,4 0,5 20 26,1 5,5 21,6 1,3 0,3 17,0 1,2 1,5 30 37,9 8,1 29,0 1,7 0,5 20,6 1,7 2,0 40 47,0 10,7 38,1 2,1 0,6 25,2 2,1 2,3 50 56,9 13,9 44,5 2,3 0,8 27,3 2,3 2,6 60 62,6 16,5 50,0 2,6 1,0 31,0 2,6 2,9 70 67,8 19,3 56,5 2,8 1,3 34,7 2,8 3,1 80 76,0 21,2 58,9 3,0 1,4 38,1 3,0 3,7 90 82,3 24,3 65,1 3,1 1,5 40,5 3,1 4,0 101 90,1 26,3 67,3 3,7 1,6 43,1 3,7 4,7 minimum air flow through the masonry construction is observed in those specimen made from aerated concrete blocks (no. 5), with an average air flow of 0.8 m³/h at 50 pa pressure difference. these brick structures were sealed with mortar joints both vertically and horizontally. also measurements showed that the average air flow rate at 50 pa pressure difference through the wall structure of calcium silicate blocks (specimen no. 4) is 2.3 m³/h, and the ceramic tiles stone (specimen no. 6) – 27.3 m³/h. these brick structures were equipped with only horizontal masonry joints. all measured masonry structures specimens’ air permeability, changing the pressure difference, is shown in figure 3. fig. 3. air permeability measurement results of masonry structures specimens by changing pressure difference the results in figure 3 shows that least airtight specimens at a 50 pa pressure difference were masonry structure of expanded clay blocks (no. 1, no. 2 and no. 3) with an air permeability of 98.7 m³/h·m 2 , 24.1 m³/h ·m 2 and 73.6 m³/h· m 2 . the most airtight specimens were of aerated concrete blocks (no.5, v a = 1,2 m³/h·m²), silicate masonry blocks (no.7, v a = 5,5 m³/h·m² and no.4, v a = 4,6 m³/h·m²) and ceramic blocks (no.8, v a = 3,5 m³/h·m²). the analysis of masonry installation technologies on the specimen air permeability suggested that the air flow depends on the arrangement of the masonry joints and 0 20 40 60 80 100 120 140 160 180 0 50 100 a i r p e r m e a b i l i t y v a , m 3 / h m 2 the pressure difference ∆p, pa 1 2 3 4 5 8 7 6 � � : �� �,� = �� �,� = ⋯ = �� � ; � � = �� �,� ≠ �� �,� (4) the null hypothesis h 0 states that the vertical joints of masonry installation do not affect the air permeability of the masonry structure. h 1 hypothesis states that at least two specimen averages are different. the following formula is used to verify both assumptions (formula 5): � = ∑ � � �� �,� − �� � ��� ��� � − 1 ∙ � − � ∑ ∑ �� �,�� − �� �,� ���� ��� � ��� (5) where: f – test statistic; n – statistical array. the level of significance was α = 0.05. this size is chosen so that the first type of error equal to α. the probability that the criterion of f statistics is not less than the observed realization t, expressed in pvalue of p = p (t ≥ t), where h 0 is correct the hypothesis h 0 is rejected if the p-value < α (h 1 is favoured, not all means are equal). otherwise, h 0 is favoured (p-value ≥ α) . in order to determine which of masonry structures air permeability specimen averages are significantly different, “bonferroni correction post hoc” test was used, based on the so-called q stjudent distance statistic were applied. averages iav , _ and ja v , are statistically significantly different, according to 6, 7, 8 formulas: ��� �,� − �� �,� � > ���; (6) ��� = � ��� � ����� − �, ��; (7) ��� = ∑ ∑ �� �,�� − �� � ���� ��� � ��� � − � (8) where: tsd – “bonferroni correction post hoc” test; msw – unbiased (inner) estimator of dispersion; q a – the critical value of q statistic’s α level; n the size of the sample. 3. results in order to determine the amount of air flow through the fragments of masonry construction, air permeability test was carried out. average air flow values are given in table 2. from the results shown in table 2, it can be observed that the greatest air flow occurred in specimens made from expanded clay blocks (no. 1 and no. 3), at 50 pa pressure difference an average air flow was 44.5 m³/h and 56.9 m³/h respectively. the density of the specimens was the same ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had horizontal masonry joints installed, specimens no. 3 had both horizontal and vertical masonry joints installed. masonry installation technology has resulted in different air flow performance. if vertical masonry joints are not installed, air flow through the wall structure increases. table 2. average results of air flow through specimens δp, pa specimen no. 1 2 3 4 5 6 7 8 air flow v 0t , m 3 /h 10 14,7 2,4 11,7 0,4 0,1 10,5 0,4 0,5 20 26,1 5,5 21,6 1,3 0,3 17,0 1,2 1,5 30 37,9 8,1 29,0 1,7 0,5 20,6 1,7 2,0 40 47,0 10,7 38,1 2,1 0,6 25,2 2,1 2,3 50 56,9 13,9 44,5 2,3 0,8 27,3 2,3 2,6 60 62,6 16,5 50,0 2,6 1,0 31,0 2,6 2,9 70 67,8 19,3 56,5 2,8 1,3 34,7 2,8 3,1 80 76,0 21,2 58,9 3,0 1,4 38,1 3,0 3,7 90 82,3 24,3 65,1 3,1 1,5 40,5 3,1 4,0 101 90,1 26,3 67,3 3,7 1,6 43,1 3,7 4,7 minimum air flow through the masonry construction is observed in those specimen made from aerated concrete blocks (no. 5), with an average air flow of 0.8 m³/h at 50 pa pressure difference. these brick structures were sealed with mortar joints both vertically and horizontally. also measurements showed that the average air flow rate at 50 pa pressure difference through the wall structure of calcium silicate blocks (specimen no. 4) is 2.3 m³/h, and the ceramic tiles stone (specimen no. 6) – 27.3 m³/h. these brick structures were equipped with only horizontal masonry joints. all measured masonry structures specimens’ air permeability, changing the pressure difference, is shown in figure 3. fig. 3. air permeability measurement results of masonry structures specimens by changing pressure difference the results in figure 3 shows that least airtight specimens at a 50 pa pressure difference were masonry structure of expanded clay blocks (no. 1, no. 2 and no. 3) with an air permeability of 98.7 m³/h·m 2 , 24.1 m³/h ·m 2 and 73.6 m³/h· m 2 . the most airtight specimens were of aerated concrete blocks (no.5, v a = 1,2 m³/h·m²), silicate masonry blocks (no.7, v a = 5,5 m³/h·m² and no.4, v a = 4,6 m³/h·m²) and ceramic blocks (no.8, v a = 3,5 m³/h·m²). the analysis of masonry installation technologies on the specimen air permeability suggested that the air flow depends on the arrangement of the masonry joints and 0 20 40 60 80 100 120 140 160 180 0 50 100 a i r p e r m e a b i l i t y v a , m 3 / h m 2 the pressure difference ∆p, pa 1 2 3 4 5 8 7 6 in order to determine the amount of air flow through the fragments of masonry construction, air permeability test was carried out. average air flow values are given in table 2. results δp, pa specimen no. 1 2 3 4 5 6 7 8 air flow v 0t , m3/h 10 14,7 2,4 11,7 0,4 0,1 10,5 0,4 0,5 20 26,1 5,5 21,6 1,3 0,3 17,0 1,2 1,5 30 37,9 8,1 29,0 1,7 0,5 20,6 1,7 2,0 40 47,0 10,7 38,1 2,1 0,6 25,2 2,1 2,3 50 56,9 13,9 44,5 2,3 0,8 27,3 2,3 2,6 60 62,6 16,5 50,0 2,6 1,0 31,0 2,6 2,9 70 67,8 19,3 56,5 2,8 1,3 34,7 2,8 3,1 80 76,0 21,2 58,9 3,0 1,4 38,1 3,0 3,7 90 82,3 24,3 65,1 3,1 1,5 40,5 3,1 4,0 101 90,1 26,3 67,3 3,7 1,6 43,1 3,7 4,7 from the results shown in table 2, it can be observed that the greatest air flow occurred in specimens made from expanded clay blocks (no. 1 and no. 3), at 50 pa pressure difference an average air flow was 44.5 m³/h and 56.9 m³/h respectively. the density of the specimens was the same ρ = 650 kg/m3, but the installation of masonry joints was different: specimen no. 1 had horizontal masonry joints installed, specimens no. 3 had both horizontal and vertical masonry joints installed. masonry installation technology has resulted in different air flow performance. if vertical masonry joints are not installed, air flow through the wall structure increases. table 1 average results of air flow through specimens journal of sustainable architecture and civil engineering 2014/4/9 78 minimum air flow through the masonry construction is observed in those specimen made from aerated concrete blocks (no. 5), with an average air flow of 0.8 m³/h at 50 pa pressure difference. these brick structures were sealed with mortar joints both vertically and horizontally. also measurements showed that the average air flow rate at 50 pa pressure difference through the wall structure of calcium silicate blocks (specimen no. 4) is 2.3 m³/h, and the ceramic tiles (4) the null hypothesis h 0 states that the vertical joints of masonry installation do not affect the air permeability of the masonry structure. h 1 hypothesis states that at least two specimen averages are different. the following formula is used to verify both assumptions (formula 5): (5) where: f – test statistic; n – statistical array. the level of significance was α = 0.05. this size is chosen so that the first type of error equal to α. the probability that the criterion of f statistics is not less than the observed realization t, expressed in pvalue of p = p (t ≥ t), where h 0 is correct the hypothesis h 0 is rejected if the p-value < α (h 1 is favoured, not all means are equal). otherwise, h 0 is favoured (p-value ≥ α) . in order to determine which of masonry structures air permeability specimen averages are significantly different, “bonferroni correction post hoc” test was used, based on the so-called q stjudent distance statistic were applied. averages iav , _ and ja v , are statistically significantly different, according to 6, 7, 8 formulas: (6) (7) (8) where: tsd – “bonferroni correction post hoc” test; msw – unbiased (inner) estimator of dispersion; q a – the critical value of q statistic’s α level; n the size of the sample. 3. results in order to determine the amount of air flow through the fragments of masonry construction, air permeability test was carried out. average air flow values are given in table 2. from the results shown in table 2, it can be observed that the greatest air flow occurred in specimens made from expanded clay blocks (no. 1 and no. 3), at 50 pa pressure difference an average air flow was 44.5 m³/h and 56.9 m³/h respectively. the density of the specimens was the same ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had horizontal masonry joints installed, specimens no. 3 had both horizontal and vertical masonry joints installed. masonry installation technology has resulted in different air flow performance. if vertical masonry joints are not installed, air flow through the wall structure increases. table 2. average results of air flow through specimens δp, specimen no. pa 1 2 3 4 5 6 7 8 air flow v 0t , m 3 /h 10 14,7 2,4 11,7 0,4 0,1 10,5 0,4 0,5 20 26,1 5,5 21,6 1,3 0,3 17,0 1,2 1,5 30 37,9 8,1 29,0 1,7 0,5 20,6 1,7 2,0 40 47,0 10,7 38,1 2,1 0,6 25,2 2,1 2,3 50 56,9 13,9 44,5 2,3 0,8 27,3 2,3 2,6 60 62,6 16,5 50,0 2,6 1,0 31,0 2,6 2,9 70 67,8 19,3 56,5 2,8 1,3 34,7 2,8 3,1 80 76,0 21,2 58,9 3,0 1,4 38,1 3,0 3,7 90 82,3 24,3 65,1 3,1 1,5 40,5 3,1 4,0 101 90,1 26,3 67,3 3,7 1,6 43,1 3,7 4,7 minimum air flow through the masonry construction is observed in those specimen made from aerated concrete blocks (no. 5), with an average air flow of 0.8 m³/h at 50 pa pressure difference. these brick structures were sealed with mortar joints both vertically and horizontally. also measurements showed that the average air flow rate at 50 pa pressure difference through the wall structure of calcium silicate blocks (specimen no. 4) is 2.3 m³/h, and the ceramic tiles stone (specimen no. 6) – 27.3 m³/h. these brick structures were equipped with only horizontal masonry joints. all measured masonry structures specimens’ air permeability, changing the pressure difference, is shown in figure 3. fig. 3. air permeability measurement results of masonry structures specimens by changing pressure difference the results in figure 3 shows that least airtight specimens at a 50 pa pressure difference were masonry structure of expanded clay blocks (no. 1, no. 2 and no. 3) with an air permeability of 98.7 m³/h·m 2 , 24.1 m³/h ·m 2 and 73.6 m³/h· m 2 . the most airtight specimens were of aerated concrete blocks (no.5, v a = 1,2 m³/h·m²), silicate masonry blocks (no.7, v a = 5,5 m³/h·m² and no.4, v a = 4,6 m³/h·m²) and ceramic blocks (no.8, v a = 3,5 m³/h·m²). the analysis of masonry installation technologies on the specimen air permeability suggested that the air flow depends on the arrangement of the masonry joints and filling. changing the pressure difference and changing the masonry joints technology, air permeability results through masonry specimens are presented in the figures 4, 5 and 6. masonry specimens of expanded clay blocks had the same density ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had vertical masonry joints installed, specimen no. 3 had both horizontal and vertical masonry joints were installed. masonry installation technology has led to different results. when vertical masonry joints are not installed, air tightness through the wall structure reduces. specimen no. 1 air permeability at 50 pa pressure difference was v a = 98,7 m³/h·m², and specimen nr. 3 v a = 73,6 m³/h·m². the estimated f-statistic p-value = 0.06 is greater than significance level of 0.05, so we reject the hypothesis of air permeability values mean equality. parameter v a averages are significantly different. in the masonry construction of expanded clay blocks, the installation of vertical joints affects the air permeability of construction. fig. 4. air permeability measurement results of expanded clay masonry structure blocks (no. 1 and 3) by changing pressure difference and masonry joins technology. fig. 5. air permeability measurement results of silicate concrete masonry structure blocks (no. 4 and 7) by changing installation technology. specimens of silicate masonry blocks joints installation differed: specimen no. 4 had vertical masonry joints installed; specimen no. 7 had both horizontal and vertical masonry joints installed. fig. 6. air permeability measurement results of ceramic masonry structure blocks (no. 6 and 8) by changing installation technology. specimen no. 4 air permeability at 50 pa pressure difference was 5.5 m³/h ·m ², and the specimen no. 7 4.6 m³/h ·m 2 . the estimated f-statistic p-value = 0.058 is greater than the significance level of 0.05, so we accept the hypothesis of the air permeability values mean equality. parameter v a mean differences were not significant. masonry structure of calcium silicate blocks vertical joints installation does not affect the air permeability of the construction. masonry structure specimens of ceramic blocks had different installation joins: specimen no.6 had vertical installation joins and specimen no.8 had horizontal and vertical installation joins. at 50 pa pressure difference air permeability of specimen no.6 was 36.2 m³/h ·m² and no.8 3.5 m³/h ·m 2 . the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05, so the hypothesis of air permeability values mean equality reject. parameter v a averages are significantly different. in the masonry construction of ceramic tiles vertical joints installation affect the overall air permeability of construction. “bonferroni application of a post hoc” test (6, 7, 8 formulas) suggests that masonry structure of ceramic tiles v a average is statistically significantly different from the other masonry structures air permeability values studied in this work. the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05. the statistical assessment of air permeability dependency of masonry structures type is graphically displayed on the graph (fig. 7). fig. 7. the statistical assessment of air permeability dependency of masonry structures type at reference pressure difference 50 pa. silicate concrete expanded clay ceramic masonry joints technology, air permeability results through masonry specimens are presented in the figures 4, 5 and 6. masonry specimens of expanded clay blocks had the same density ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had vertical masonry joints installed, specimen no. 3 had both horizontal and vertical masonry joints were installed. masonry installation technology has led to different results. when vertical masonry joints are not installed, air tightness through the wall structure reduces. specimen no. 1 air permeability at 50 pa pressure difference was v a = 98,7 m³/h·m², and specimen nr. 3 v a = 73,6 m³/h·m². the estimated f-statistic p-value = 0.06 is greater than significance level of 0.05, so we reject the hypothesis of air permeability values mean equality. parameter v a averages are significantly different. in the masonry construction of expanded clay blocks, the installation of vertical joints affects the air permeability of construction. fig. 4. air permeability measurement results of expanded clay masonry structure blocks (no. 1 and 3) by changing pressure difference and masonry joins technology. fig. 5. air permeability measurement results of silicate concrete masonry structure blocks (no. 4 and 7) by changing installation technology. specimens of silicate masonry blocks joints installation differed: specimen no. 4 had vertical masonry joints installed; specimen no. 7 had both horizontal and vertical masonry joints installed. fig. 6. air permeability measurement results of ceramic masonry structure blocks (no. 6 and 8) by changing installation technology. specimen no. 4 air permeability at 50 pa pressure difference was 5.5 m³/h ·m ², and the specimen no. 7 4.6 m³/h ·m 2 . the estimated f-statistic p-value = 0.058 is greater than the significance level of 0.05, so we accept the hypothesis of the air permeability values mean equality. parameter v a mean differences were not significant. masonry structure of calcium silicate blocks vertical joints installation does not affect the air permeability of the construction. masonry structure specimens of ceramic blocks had different installation joins: specimen no.6 had vertical installation joins and specimen no.8 had horizontal and vertical installation joins. at 50 pa pressure difference air permeability of specimen no.6 was 36.2 m³/h ·m² and no.8 3.5 m³/h ·m 2 . the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05, so the hypothesis of air permeability values mean equality reject. parameter v a averages are significantly different. in the masonry construction of ceramic tiles vertical joints installation affect the overall air permeability of construction. “bonferroni application of a post hoc” test (6, 7, 8 formulas) suggests that masonry structure of ceramic tiles v a average is statistically significantly different from the other masonry structures air permeability values studied in this work. the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05. the statistical assessment of air permeability dependency of masonry structures type is graphically displayed on the graph (fig. 7). fig. 7. the statistical assessment of air permeability dependency of masonry structures type at reference pressure difference 50 pa. silicate concrete expanded clay ceramic stone (specimen no. 6) – 27.3 m³/h. these brick structures were equipped with only horizontal masonry joints. all measured masonry structures specimens’ air permeability, changing the pressure difference, is shown in figure 3. the results in figure 3 shows that least airtight specimens at a 50 pa pressure difference were masonry structure of expanded clay blocks (no. 1, no. 2 and no. 3) with an air permeability of 98.7 m³/h·m2, 24.1 m³/h ·m2 and 73.6 m³/h· m2. the most airtight specimens were of aerated concrete blocks (no.5, v a = 1,2 m³/h·m²), silicate masonry blocks (no.7, v a = 5,5 m³/h·m² and no.4, v a = 4,6 m³/h·m²) and ceramic blocks (no.8, v a = 3,5 m³/h·m²). the analysis of masonry installation technologies on the specimen air permeability suggested that the air flow depends on the arrangement of the masonry joints and filling. changing the pressure difference and changing the masonry joints technology, air permeability results through masonry specimens are presented in the figures 4, 5 and 6. masonry specimens of expanded clay blocks had the same density ρ = 650 kg/m3, but the installation of masonry joints was different: specimen no. 1 had vertical masonry joints installed, specimen no. 3 had both horizontal and vertical masonry joints were installed. masonry installation technology has led to different results. when vertical masonry joints are not installed, air tightness through the wall structure reduces. specimen no. 1 air permeability at 50 pa pressure difference was v a = 98,7 m³/h·m², and fig. 3 air permeability measurement results of masonry structures specimens by changing pressure difference fig. 4 air permeability measurement results of expanded clay masonry structure blocks (no. 1 and 3) by changing pressure difference and masonry joins technology fig. 5 air permeability measurement results of silicate concrete masonry structure blocks (no. 4 and 7) by changing installation technology 79 journal of sustainable architecture and civil engineering 2014/4/9 masonry joints technology, air permeability results through masonry specimens are presented in the figures 4, 5 and 6. masonry specimens of expanded clay blocks had the same density ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had vertical masonry joints installed, specimen no. 3 had both horizontal and vertical masonry joints were installed. masonry installation technology has led to different results. when vertical masonry joints are not installed, air tightness through the wall structure reduces. specimen no. 1 air permeability at 50 pa pressure difference was v a = 98,7 m³/h·m², and specimen nr. 3 v a = 73,6 m³/h·m². the estimated f-statistic p-value = 0.06 is greater than significance level of 0.05, so we reject the hypothesis of air permeability values mean equality. parameter v a averages are significantly different. in the masonry construction of expanded clay blocks, the installation of vertical joints affects the air permeability of construction. fig. 4. air permeability measurement results of expanded clay masonry structure blocks (no. 1 and 3) by changing pressure difference and masonry joins technology. fig. 5. air permeability measurement results of silicate concrete masonry structure blocks (no. 4 and 7) by changing installation technology. specimens of silicate masonry blocks joints installation differed: specimen no. 4 had vertical masonry joints installed; specimen no. 7 had both horizontal and vertical masonry joints installed. fig. 6. air permeability measurement results of ceramic masonry structure blocks (no. 6 and 8) by changing installation technology. specimen no. 4 air permeability at 50 pa pressure difference was 5.5 m³/h ·m ², and the specimen no. 7 4.6 m³/h ·m 2 . the estimated f-statistic p-value = 0.058 is greater than the significance level of 0.05, so we accept the hypothesis of the air permeability values mean equality. parameter v a mean differences were not significant. masonry structure of calcium silicate blocks vertical joints installation does not affect the air permeability of the construction. masonry structure specimens of ceramic blocks had different installation joins: specimen no.6 had vertical installation joins and specimen no.8 had horizontal and vertical installation joins. at 50 pa pressure difference air permeability of specimen no.6 was 36.2 m³/h ·m² and no.8 3.5 m³/h ·m 2 . the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05, so the hypothesis of air permeability values mean equality reject. parameter v a averages are significantly different. in the masonry construction of ceramic tiles vertical joints installation affect the overall air permeability of construction. “bonferroni application of a post hoc” test (6, 7, 8 formulas) suggests that masonry structure of ceramic tiles v a average is statistically significantly different from the other masonry structures air permeability values studied in this work. the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05. the statistical assessment of air permeability dependency of masonry structures type is graphically displayed on the graph (fig. 7). fig. 7. the statistical assessment of air permeability dependency of masonry structures type at reference pressure difference 50 pa. silicate concrete expanded clay ceramic masonry joints technology, air permeability results through masonry specimens are presented in the figures 4, 5 and 6. masonry specimens of expanded clay blocks had the same density ρ = 650 kg/m 3 , but the installation of masonry joints was different: specimen no. 1 had vertical masonry joints installed, specimen no. 3 had both horizontal and vertical masonry joints were installed. masonry installation technology has led to different results. when vertical masonry joints are not installed, air tightness through the wall structure reduces. specimen no. 1 air permeability at 50 pa pressure difference was v a = 98,7 m³/h·m², and specimen nr. 3 v a = 73,6 m³/h·m². the estimated f-statistic p-value = 0.06 is greater than significance level of 0.05, so we reject the hypothesis of air permeability values mean equality. parameter v a averages are significantly different. in the masonry construction of expanded clay blocks, the installation of vertical joints affects the air permeability of construction. fig. 4. air permeability measurement results of expanded clay masonry structure blocks (no. 1 and 3) by changing pressure difference and masonry joins technology. fig. 5. air permeability measurement results of silicate concrete masonry structure blocks (no. 4 and 7) by changing installation technology. specimens of silicate masonry blocks joints installation differed: specimen no. 4 had vertical masonry joints installed; specimen no. 7 had both horizontal and vertical masonry joints installed. fig. 6. air permeability measurement results of ceramic masonry structure blocks (no. 6 and 8) by changing installation technology. specimen no. 4 air permeability at 50 pa pressure difference was 5.5 m³/h ·m ², and the specimen no. 7 4.6 m³/h ·m 2 . the estimated f-statistic p-value = 0.058 is greater than the significance level of 0.05, so we accept the hypothesis of the air permeability values mean equality. parameter v a mean differences were not significant. masonry structure of calcium silicate blocks vertical joints installation does not affect the air permeability of the construction. masonry structure specimens of ceramic blocks had different installation joins: specimen no.6 had vertical installation joins and specimen no.8 had horizontal and vertical installation joins. at 50 pa pressure difference air permeability of specimen no.6 was 36.2 m³/h ·m² and no.8 3.5 m³/h ·m 2 . the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05, so the hypothesis of air permeability values mean equality reject. parameter v a averages are significantly different. in the masonry construction of ceramic tiles vertical joints installation affect the overall air permeability of construction. “bonferroni application of a post hoc” test (6, 7, 8 formulas) suggests that masonry structure of ceramic tiles v a average is statistically significantly different from the other masonry structures air permeability values studied in this work. the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05. the statistical assessment of air permeability dependency of masonry structures type is graphically displayed on the graph (fig. 7). fig. 7. the statistical assessment of air permeability dependency of masonry structures type at reference pressure difference 50 pa. silicate concrete expanded clay ceramic specimen nr. 3 v a = 73,6 m³/h·m². the estimated f-statistic p-value = 0.06 is greater than significance level of 0.05, so we reject the hypothesis of air permeability values mean equality. parameter v a averages are significantly different. in the masonry construction of expanded clay blocks, the installation of vertical joints affects the air permeability of construction. specimens of silicate masonry blocks joints installation differed: specimen no. 4 had vertical masonry joints installed; specimen no. 7 had both horizontal and vertical masonry joints installed. specimen no. 4 air permeability at 50 pa pressure difference was 5.5 m³/h ·m ², and the specimen no. 7 4.6 m³/h ·m2. the estimated f-statistic p-value = 0.058 is greater than the significance level of 0.05, so we accept the hypothesis of the air permeability values mean equality. parameter v a mean differences were not significant. masonry structure of calcium silicate blocks vertical joints installation does not affect the air permeability of the construction. masonry structure specimens of ceramic blocks had different installation joins: specimen no.6 had vertical installation joins and specimen no.8 had horizontal and vertical installation joins. at 50 pa pressure difference air permeability of specimen no.6 was 36.2 m³/h ·m² and no.8 3.5 m³/h ·m2. the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05, so the hypothesis of air permeability values mean equality reject. parameter v a averages are significantly different. in the masonry construction of ceramic tiles vertical joints installation affect the overall air permeability of construction. “bonferroni application of a post hoc” test (6, 7, 8 formulas) suggests that masonry structure of ceramic tiles v a average is statistically significantly different from the other masonry structures air permeability values studied in this work. the estimated f-statistic p-value = 0.00 is less than the significance level of 0.05. the statistical assessment of air permeability dependency of masonry structures type is graphically displayed on the graph (fig. 7). the study of air permeability through various types of masonry construction suggests that the air tightness of the construction affects the material macrostructure. macrostructure nature is characterized by small and large pore ratio, pore degree of openness and the capillary number connecting them. macrostructure is one of the key determinants that stipulates the cellular concrete properties. porous concrete macrostructure is formed in its production (formation) process and fixated binder hydration. it is a fine-grained structure, although the predominant pore diameter of about 3 mm, but it is closed-cell system. therefore, the porous concrete structure is tight enough for air flow at discussion fig. 6 air permeability measurement results of ceramic masonry structure blocks (no. 6 and 8) by changing installation technology fig. 7 the statistical assessment of air permeability dependency of masonry structures type at reference pressure difference 50 pa journal of sustainable architecture and civil engineering 2014/4/9 80 v a = 1.2 m³ / h·m2 at ∆p = 50 pa. in this paper studied ceramic tiles and calcium silicate blocks macrostructure is a fine-grained, with a porosity of 20% and 30% (kumaoka, 2000). evaluating from the air permeability aspect, the results show that the structure of the ceramic brick and calcium silicate blocks are sufficiently tight. in summary, the above described masonry structures are sufficiently airtight, but the analysis of the resulting air permeability through masonry structures studied results show that there is air flow. this small air movement can be explained by the fact that the masonry structure is heterogeneous and the resulting micro-cracks within the concrete blocks and masonry joints installed, at a differential pressure, air movement conditions occur. the analysis of air permeability through the masonry construction of expanded clay block values shows that in this case the air permeability value is the most different from the other air permeability values of masonry structures tested in this work . this was a result of coarse material structure of expanded clay blocks, which is characterized by open porosity and capillary system. this conclusion is further strengthened by the air permeability results obtained from different density expanded clay blocks: masonry construction of low density (ρ = 650 kg/m3) expanded clay blocks air permeability at 50 pa pressure difference was between v a = 73.6 m³/h·m2; and masonry construction of higher density (ρ = 883 kg/m3) expanded clay blocks air permeability at 50 pa pressure difference, v a = 24.1 m³/h·m2. the same coarse-grained materials, but different densities of air permeability values varied about 3 times. this has resulted in pore diameter size, degree of openness and capillary number connecting them. masonry is a heterogeneous material and air permeability depends not only on the block macrostructure, but also on the masonry joints nature and technology. the analysis of the differences between the masonry structures, which have been equipped with only horizontal masonry joints, and masonry structures, which had both horizontal and vertical joints installed, showed that masonry structures, only with vertical masonry joints had air permeability results higher. measurements showed that the masonry of the expanded clay blocks, installing vertical joints can reduce the air permeability about 3 times and the masonry of ceramic tiles 10 times. meanwhile, the masonry of silicate blocks vertical joints installation influence the design air permeability negligibly. this can be explained by the fact that during masonry, when putting blocks next to each other, small gaps are formed. the latter is a result from defects in the block and size variations, uneven rows of masonry, the block tie inaccuracy. masonry construction rules (st 121895674.06:2009) requires this type of exterior surface covered with plaster. however, the layer of plaster, exposed to various adverse climatic factors during the operation, loses its protective function and a masonry structure becomes permeable to air and inefficient from thermal point of view. in this paper obtained masonry structures air permeability analysis of the results shows that building envelope air permeability depends on the masonry structure of the material and the installation of the masonry technology. building envelope air permeability measurements showed that the construction of the masonry expanded clay blocks (because of coarse macrostructure) were 70-90% more air permeable than other masonry structures investigated in this work. it is necessary to protect masonry structures from expanded clay blocks against adverse external climatic factors (wind, rain) by plastering the surfaces. the analysis of masonry installation technologies on the specimen air permeability suggests that the air flow depends on the arrangement of the masonry joints and installation. the study found that for the masonry of the ceramic blocks, installation of horizontal and vertical joints can reduce the specimen air permeability 10 times comparing the structure only with vertical installation joins. despite the masonry structures of ceramic tiles outer surface covered with plaster, it is recommended to install vertical and horizontal masonry joints. conclusions 81 journal of sustainable architecture and civil engineering 2014/4/9 work is carried out in accordance with the kaunas university of technology research interests “buildings’ energy performance and heat transfer in buildings research” program. acknowledgment ambrosio a., f., r.; isola, d., m.; ficco, g.; tassini, f. 2012. experimental analysis of air tightness in mediterranen buildings using the fan pressurization method. building ant environment, 53, 16-25. becker, r. 2010. air leakage of curtain walls – diagnostics and remediation, journal of building physics, 34(1), 57-75. http://dx.doi. org/10.1177/1744259109349665 benazzouk, a.; douzane, 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with examples and exercises, journal of building physics 35: 192-209. hong, c.; zhang x.; han j.; meng s.; du s. 2012. synthesis, microstructure and properties of highstrength porous ceramics, ceramic materials – progress in modern ceramics, pro. feng shi (ed.), isbn: 978-953-51-0476-6, intech, p.109-110. kalamees, t.; kurnitski, j.; jokisalo, j.; eskola, l.; jokiranta, k.; vinba, j. 2010. measured and simulated air pressure conditions in finnish residential buildings, building serv. eng. res. technol. 31(2), 177-190. http://dx.doi. org/10.1177/0143624410363655 kovanen, k.a.; laamanen, j.; kauppinen, t.; duanmu, l. 2009. air tightness of new residential referencesbuildings in finland, 6th international symposium on heating, ventilating and air conditioning, vols i-iii, proceedings, p.p. 207-213. kumaoka, s., a., s. 2000 porous ceramics provided with amorphous pore surfaces, united states patent no.us 6,420,292 b1, p.16. lst en-998-2:2003 specification for mortar for masonry part 2: masonry mortar, brussels. 36 p. matrosov, y., a.; chao, m.; majersik, c. 2007. increasing thermal performance and energy efficiency of buildings in russia: problems and solutions, ashrae. available from internet < http:// www.cenef.ru/file/st-267e.pdf>. ohji, t.; fukushima, m. 2012 macro-porous ceramics: processing and properties, international materials reviews, 57(2): 115-131. http://dx.doi.org /10.1179/1743280411y.0000000006 pan, w. 2010. relationships between air-tightness and its influencing factors of post-2006 vew-build dwellings in the uk, building and environment. 45, 2387-2399. http://dx.doi.org/10.1016/j. buildenv.2010.04.011 quenard, d., a.; xu, k.; kunzel, h., m.; bentz, d., p.; martys, n. s. 1998. microstructure and transport properties of porous building materials, materials and structures, 31(5): 317-324. http://dx.doi. org/10.1007/bf02480673 salahov, a.; tagirov, l.; salahova, r.; parfenov, v.; ljadov, n. 2011. characterization of building material pore and strength, 12: 25 -27 (in russian). santos, g., h.; mendes, n. 2009. combined heat, air and moisture (ham) transfer model for porous building materials, journal of building physics, 32: 203-220. http://dx.doi. org/10.1177/1744259108098340 sedmale, g.; cimmers, a.; sedmalis, u. 2009. charasteristics of sillite clay and compositions for porous building ceramics production, chemine technologija, 2: 18-21. sfakianaki, a.; pavlou, k., santamouris, m. et al. 2008. air tightness measurements of residential houses in athens, greece, building and environment. 43, 398-405. http://dx.doi.org/10.1016/j. buildenv.2007.01.006 journal of sustainable architecture and civil engineering 2014/4/9 82 smeds, j; wall, m. 2007. enhanced energy conservation in houses through high performance design, energy and buildings, 39, 273-278. http://dx.doi.org/10.1016/j. enbuild.2006.07.003 st 121895674.06:2009. masonry works. lithuanian buildeers association. available from internet < http:// www.statybostaisykles.lt/node/322>. studart, a., r.; gonzenbach, u., t.; tervoort, e.; gauckler, l., j. 2006. processing routes to macroporous ceramics: a review, journal of the american ceramic sočiety 89(6): 1771-1789. tariku, f.; kumaran, k.; fazio, p. 2010. transient model for coupled heat, air and moisture transfer through multilayered porous media. international journal of heat and mass transfer 53: 3035–3044. http://dx.doi.org/10.1016/j. ijheatmasstransfer.2010.03.024 jolanta šadauskienė researcher laboratory of building physics at the institute of architecture and construction, ktu assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area the moisture state of the building constructions; physicaltechnical processes in building envelopes; heat loss in buildings address tunelio st. 60, lt-44405, kaunas, lithuania. tel. +370 37 350779 e-mail: jolanta.sadauskiene@ ktu.lt karolis banionis researcher laboratory of building physics at the institute of architecture and construction, ktu lector kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area energy efficiency and air permeability of buildings, heat transfer and thermal insulation, thermal impacts of solar radiation address tunelio st. 60, lt-44405, kaunas, lithuania. tel. +370 37 350779 e-mail: karolis.banionis@ktu.lt valdas paukštys researcher laboratory of building physics at the institute of architecture and construction, ktu assoc. professor kaunas university of technology, faculty of civil engineering and architecture, department of building energy systems main research area the moisture state of the building constructions; physicaltechnical processes and heat loss in building envelopes address studentų st. 48, lt-51367 kaunas, lithuania. tel. +370 37 300486 e-mail: valdas.paukstys@ktu.lt about the authors 40 darnioji architektūra ir statyba 2013. no. 1(2) journal of sustainable architecture and civil engineering issn 2029–9990 investigation into thermal capacitance of the building envelope patrikas bruzgevičius1, arūnas burlingis1, vytautas stankevičius1, darius pupeikis2, rosita norvaišienė1, karolis banionis1 1institute of architecture and construction of kaunas university of technology, tunelio st. 60, lt-44405 kaunas, lithuania 2kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania * corresponding author: patrikas.bruzgevicius@yahoo.com http://dx.doi.org/10.5755/j01.sace.1.2.3543 the purpose of this research is to determine the actual effective thermal capacitance of the building envelope in respect of the place of thermal layer in the enclosure. the actual effective thermal capacitance of the building envelope is estimated by calculating the thermal capacitance of building enclosure layers in order to find out the active thermal capacitance of the enclosure. this research analyses unsteady heat transfer cases. the calculation principle of such transfers is based on the finite elements method. the specific value of the fourier number, which gives calculations the optimal accuracy, is determined. this paper also discusses three types of envelope constructions. in all three cases, thermal resistance of the envelopes coincides; only the position of thermal insulation layer in the envelopes is different. in all three cases, time delay of the indoor air temperature in respect of the outdoor air temperature, as well as decrement factors of the oscillation amplitude are calculated. these factors of inertia were determined at the continuous outdoor air temperature oscillation. the research revealed that continuous outdoor air temperature oscillations through multi-layered building enclosures are suppressed by high thermal capacitance enclosure layers, independently from their position. high thermal capacitance enclosure layers oriented to the interior of the premises suppress the fluctuations more efficiently than those oriented to the exterior. keywords: building envelope, enclosure, time constant, fourier number, thermal capacitance, time delay, decrement factor. 1. introduction when analysing unsteady thermal processes in buildings and classifying the buildings according to their thermal inertia factors, it is important to properly evaluate the influence of building enclosures on the internal temperature fluctuation due to the outdoor temperature changes. the effective thermal capacitance ceff of the building envelope, thermal time constant τ and actual thermal delay are the indicators of the thermal inertia of the building. therefore, it is important to evaluate them appropriately. the methodology of the lithuanian standards board (lst en iso 13790:2008) classifies buildings into inertia classes according to the value of time constant. thermal time constant of the building τ is expressed as a proportion between the internal active thermal capacitance of the building cm and heat transfer coefficient of the building h (lst en iso 13790:2008): )(, 3600/ h hh c vt m + =τ (1) where: cm – internal active thermal capacitance, j/k; ht – heat transfer coefficient of building enclosures, w/k; hv – ventilation heat loss coefficient, w/k. the average active thermal capacitance cm is defined as the heat accumulated inside the building, when the internal air temperature oscillates according to the sinusoid with the period t-24h and the amplitude 1k (lst en iso 13790:2008). the value of the internal thermal capacitance of the building depends on the amplitude of temperature oscillation in the premises; the allowed fluctuation limits depend on the purpose of the premises (šeduikytė et al. 2008, lst en iso 7730, str 2.09.02:2005). the standard (lst en iso 13790:2008) evaluates active thermal capacitance cm only inside the building, i.e. it evaluates energy costs per year when temperature fluctuations occur inside the building, which is not a very accurate method for evaluating the complex influence of the building envelope on the thermal regime of the premises and selecting the capacity of the heating system. continuous fluctuations of the outdoor air temperature affect the building enclosures first, and only then these fluctuations make an impact on the thermal regime of the premises. swedish scientists adamsson, dafgard, rydberg and peterson (berg-hallberg 1985) were among the first to classify buildings according to the value of time constant. 41 when classifying buildings, the scientists evaluated the thermal capacitance of the building envelope taking into account all the layers of the enclosure, or half of the thermal capacitance of the enclosure, or the internal layers of the enclosure up to thermal insulation layer. according to (kalema et al. 2006), the thermal capacitance of the construction taken into account is limited to 0.10 m from the surface, or to the first insulation layer. when classifying buildings according to the time constant factor, antonopoulos et al. (1995) calculate thermal capacitance using the lump capacitance method: )/(, kjcc nnnρν∑= (2) where: νn, ρn and cn are the volume, density and specific heat, respectively, of element n. thermal regime inside the building is affected in two ways: due to infiltration and through the external building envelope. in reality, most of the buildings are made of enclosures of different construction types, depending on the purpose and technological regime of the building and dominant construction traditions in the country. the massive layer of multi-layered enclosures can be oriented to the exterior or the interior of the building, or it can be in the middle of the enclosure. thermal capacitance is an important quality that enables walls to absorb, store and later release thermal energy into the building space. the aim of this work is to determine the effect of massive layer position in the enclosure on the thermal inertia of the enclosure. 2. methods the accuracy of calculations of unsteady heat transfer using the finite elements method depends on the selected values of fourier and biot numbers. the fourier number is designated by the symbol fo and the equation for every layer of this number is (stankevičius et al. 2000, incropera et al. 2007, hagentoft 2001): 2d za fo d⋅ = (3) the fourier number can also be expressed as: where: ν n , ρ n and c n are the volume, density and specific heat, respectively, of element n. thermal regime inside the building is affected in two ways: due to infiltration and through the external building envelope. in reality, most of the buildings are made of enclosures of different construction types, depending on the purpose and technological regime of the building and dominant construction traditions in the country. the massive layer of multi-layered enclosures can be oriented to the exterior or the interior of the building, or it can be in the middle of the enclosure. thermal capacitance is an important quality that enables walls to absorb, store and later release thermal energy into the building space. the aim of this work is to determine the effect of massive layer position in the enclosure on the thermal inertia of the enclosure. 2. methods the accuracy of calculations of unsteady heat transfer using the finite elements method depends on the selected values of fourier and biot numbers. the fourier number is designated by the symbol f o and the equation for every layer of this number is (stankevičius et al. 2000, incropera et al. 2007, hagentoft 2001): 2 d za f o δ⋅ = (3) the fourier number can also be expressed as: ; 2 za c z rc z dc z f sl sl slslp o δ⋅= δ⋅λ = ⋅ δ = ⋅⋅ δ⋅ = ρ λ (4) where: a – the thermal diffusivity, (m 2 /s); δz – the time step, (s); d – thickness of conditional layer, (m); λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal capacitance of the layer: )/(, 2 . kmjdcc psl ⋅⋅⋅= ρ (5) where: ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)); d thickness of layer, (m). the thermal resistance of the layer: wkmdr sl /)(,/ 2 . ⋅= λ (6) where: d – thickness of material, (m); λ – thermal conductivity, (w/(m⋅k). the thermal diffusion of the layer (pupeikis et al. 2010): )/(,/ 2 . kmwd sl ⋅=λ λ (7) where: λ – thermal conductance, (w/m 2 ⋅k); λ – thermal conductivity, (w/(m⋅k)); d – thickness of layer, (m). the thermal diffusivity of the material: sm c a p /; 2 ⋅ = ρ λ (8) where: λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal diffusion of the separate layer: )/1(, 2 s d a a sl = (9) where: a sl – thermal diffusion of the material layer [1/s]; a – thermal diffusivity of material, [m 2 /s]; d – thickness of layer, [m]. the dependence of layer thickness on the fourier number and time step: )(, m f za d o δ⋅ = (10) where: a – thermal diffusivity of material, (m 2 /s); d – thickness of layer, (m); δz the time step, (s); f o fourier number. thermal diffusivity of the material a (m 2 /s; m 2 /h) shows the rate of temperature “diffusion/equalization” in the object, i.e. the part of 1 m distance per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop between two planes (points) at 1 m distance is 1k. the inverse proportion 1/a (s/m 2 ; h/m 2 ) shows the time in which the temperature equalizes between two planes (points) of the homogeneous object at 1 m distance, when the temperature drop at the initial moment is 1k. suppose, there is an eps with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), then, the calculations are performed according to (8) a=0,00000209 m 2 /s≈0,0075m 2 /h and 1/a= 478571 s/m 2 ≈133 h/m 2 . thermal diffusion of the layer a (1/s; 1/h) shows the rate of thermal “diffusion/equalization”, i.e., the part of layer thickness y per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop on both sides of the layer is 1k. the inverse proportion 1/a (s; h) shows the time in which the temperature equalizes in the homogeneous layer, when layer thickness is y and temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), d= 50mm, then, the calculations are performed according to (9): a≈3,01,(1/h) and 1/a≈0,332, (h). fourier number f o shows the thickness (depth) of “equalization” in the layer during the selected time step δz, i.e., the part of layer thickness y for the temperature to equalize in the homogeneous layer from the initial moment during the time period δz, when the temperature drop on both sides of the layer, whose thickness is y, is 1k. (4) where: a – the thermal diffusivity, (m2/s); dz – the time step, (s); d – thickness of conditional layer, (m); λ – thermal conductivity, (w/(m × k)); ρ – material density, (kg/m3); c – specific thermal capacity , (j/(kg×k)). the thermal capacitance of the layer: where: ν n , ρ n and c n are the volume, density and specific heat, respectively, of element n. thermal regime inside the building is affected in two ways: due to infiltration and through the external building envelope. in reality, most of the buildings are made of enclosures of different construction types, depending on the purpose and technological regime of the building and dominant construction traditions in the country. the massive layer of multi-layered enclosures can be oriented to the exterior or the interior of the building, or it can be in the middle of the enclosure. thermal capacitance is an important quality that enables walls to absorb, store and later release thermal energy into the building space. the aim of this work is to determine the effect of massive layer position in the enclosure on the thermal inertia of the enclosure. 2. methods the accuracy of calculations of unsteady heat transfer using the finite elements method depends on the selected values of fourier and biot numbers. the fourier number is designated by the symbol f o and the equation for every layer of this number is (stankevičius et al. 2000, incropera et al. 2007, hagentoft 2001): 2 d za f o δ⋅ = (3) the fourier number can also be expressed as: ; 2 za c z rc z dc z f sl sl slslp o δ⋅= δ⋅λ = ⋅ δ = ⋅⋅ δ⋅ = ρ λ (4) where: a – the thermal diffusivity, (m 2 /s); δz – the time step, (s); d – thickness of conditional layer, (m); λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal capacitance of the layer: )/(, 2 . kmjdcc psl ⋅⋅⋅= ρ (5) where: ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)); d thickness of layer, (m). the thermal resistance of the layer: wkmdr sl /)(,/ 2 . ⋅= λ (6) where: d – thickness of material, (m); λ – thermal conductivity, (w/(m⋅k). the thermal diffusion of the layer (pupeikis et al. 2010): )/(,/ 2 . kmwd sl ⋅=λ λ (7) where: λ – thermal conductance, (w/m 2 ⋅k); λ – thermal conductivity, (w/(m⋅k)); d – thickness of layer, (m). the thermal diffusivity of the material: sm c a p /; 2 ⋅ = ρ λ (8) where: λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal diffusion of the separate layer: )/1(, 2 s d a a sl = (9) where: a sl – thermal diffusion of the material layer [1/s]; a – thermal diffusivity of material, [m 2 /s]; d – thickness of layer, [m]. the dependence of layer thickness on the fourier number and time step: )(, m f za d o δ⋅ = (10) where: a – thermal diffusivity of material, (m 2 /s); d – thickness of layer, (m); δz the time step, (s); f o fourier number. thermal diffusivity of the material a (m 2 /s; m 2 /h) shows the rate of temperature “diffusion/equalization” in the object, i.e. the part of 1 m distance per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop between two planes (points) at 1 m distance is 1k. the inverse proportion 1/a (s/m 2 ; h/m 2 ) shows the time in which the temperature equalizes between two planes (points) of the homogeneous object at 1 m distance, when the temperature drop at the initial moment is 1k. suppose, there is an eps with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), then, the calculations are performed according to (8) a=0,00000209 m 2 /s≈0,0075m 2 /h and 1/a= 478571 s/m 2 ≈133 h/m 2 . thermal diffusion of the layer a (1/s; 1/h) shows the rate of thermal “diffusion/equalization”, i.e., the part of layer thickness y per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop on both sides of the layer is 1k. the inverse proportion 1/a (s; h) shows the time in which the temperature equalizes in the homogeneous layer, when layer thickness is y and temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), d= 50mm, then, the calculations are performed according to (9): a≈3,01,(1/h) and 1/a≈0,332, (h). fourier number f o shows the thickness (depth) of “equalization” in the layer during the selected time step δz, i.e., the part of layer thickness y for the temperature to equalize in the homogeneous layer from the initial moment during the time period δz, when the temperature drop on both sides of the layer, whose thickness is y, is 1k. (5) where: ρ – material density, (kg/m3); c – specific thermal capacity , (j/(kg×k)); d – thickness of layer, (m). the thermal resistance of the layer: where: ν n , ρ n and c n are the volume, density and specific heat, respectively, of element n. thermal regime inside the building is affected in two ways: due to infiltration and through the external building envelope. in reality, most of the buildings are made of enclosures of different construction types, depending on the purpose and technological regime of the building and dominant construction traditions in the country. the massive layer of multi-layered enclosures can be oriented to the exterior or the interior of the building, or it can be in the middle of the enclosure. thermal capacitance is an important quality that enables walls to absorb, store and later release thermal energy into the building space. the aim of this work is to determine the effect of massive layer position in the enclosure on the thermal inertia of the enclosure. 2. methods the accuracy of calculations of unsteady heat transfer using the finite elements method depends on the selected values of fourier and biot numbers. the fourier number is designated by the symbol f o and the equation for every layer of this number is (stankevičius et al. 2000, incropera et al. 2007, hagentoft 2001): 2 d za f o δ⋅ = (3) the fourier number can also be expressed as: ; 2 za c z rc z dc z f sl sl slslp o δ⋅= δ⋅λ = ⋅ δ = ⋅⋅ δ⋅ = ρ λ (4) where: a – the thermal diffusivity, (m 2 /s); δz – the time step, (s); d – thickness of conditional layer, (m); λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal capacitance of the layer: )/(, 2 . kmjdcc psl ⋅⋅⋅= ρ (5) where: ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)); d thickness of layer, (m). the thermal resistance of the layer: wkmdr sl /)(,/ 2 . ⋅= λ (6) where: d – thickness of material, (m); λ – thermal conductivity, (w/(m⋅k). the thermal diffusion of the layer (pupeikis et al. 2010): )/(,/ 2 . kmwd sl ⋅=λ λ (7) where: λ – thermal conductance, (w/m 2 ⋅k); λ – thermal conductivity, (w/(m⋅k)); d – thickness of layer, (m). the thermal diffusivity of the material: sm c a p /; 2 ⋅ = ρ λ (8) where: λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal diffusion of the separate layer: )/1(, 2 s d a a sl = (9) where: a sl – thermal diffusion of the material layer [1/s]; a – thermal diffusivity of material, [m 2 /s]; d – thickness of layer, [m]. the dependence of layer thickness on the fourier number and time step: )(, m f za d o δ⋅ = (10) where: a – thermal diffusivity of material, (m 2 /s); d – thickness of layer, (m); δz the time step, (s); f o fourier number. thermal diffusivity of the material a (m 2 /s; m 2 /h) shows the rate of temperature “diffusion/equalization” in the object, i.e. the part of 1 m distance per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop between two planes (points) at 1 m distance is 1k. the inverse proportion 1/a (s/m 2 ; h/m 2 ) shows the time in which the temperature equalizes between two planes (points) of the homogeneous object at 1 m distance, when the temperature drop at the initial moment is 1k. suppose, there is an eps with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), then, the calculations are performed according to (8) a=0,00000209 m 2 /s≈0,0075m 2 /h and 1/a= 478571 s/m 2 ≈133 h/m 2 . thermal diffusion of the layer a (1/s; 1/h) shows the rate of thermal “diffusion/equalization”, i.e., the part of layer thickness y per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop on both sides of the layer is 1k. the inverse proportion 1/a (s; h) shows the time in which the temperature equalizes in the homogeneous layer, when layer thickness is y and temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), d= 50mm, then, the calculations are performed according to (9): a≈3,01,(1/h) and 1/a≈0,332, (h). fourier number f o shows the thickness (depth) of “equalization” in the layer during the selected time step δz, i.e., the part of layer thickness y for the temperature to equalize in the homogeneous layer from the initial moment during the time period δz, when the temperature drop on both sides of the layer, whose thickness is y, is 1k. (6) where: d – thickness of material, (m); l – thermal conductivity, (w/(m × k). the thermal diffusion of the layer (pupeikis et al. 2010): where: ν n , ρ n and c n are the volume, density and specific heat, respectively, of element n. thermal regime inside the building is affected in two ways: due to infiltration and through the external building envelope. in reality, most of the buildings are made of enclosures of different construction types, depending on the purpose and technological regime of the building and dominant construction traditions in the country. the massive layer of multi-layered enclosures can be oriented to the exterior or the interior of the building, or it can be in the middle of the enclosure. thermal capacitance is an important quality that enables walls to absorb, store and later release thermal energy into the building space. the aim of this work is to determine the effect of massive layer position in the enclosure on the thermal inertia of the enclosure. 2. methods the accuracy of calculations of unsteady heat transfer using the finite elements method depends on the selected values of fourier and biot numbers. the fourier number is designated by the symbol f o and the equation for every layer of this number is (stankevičius et al. 2000, incropera et al. 2007, hagentoft 2001): 2 d za f o δ⋅ = (3) the fourier number can also be expressed as: ; 2 za c z rc z dc z f sl sl slslp o δ⋅= δ⋅λ = ⋅ δ = ⋅⋅ δ⋅ = ρ λ (4) where: a – the thermal diffusivity, (m 2 /s); δz – the time step, (s); d – thickness of conditional layer, (m); λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal capacitance of the layer: )/(, 2 . kmjdcc psl ⋅⋅⋅= ρ (5) where: ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)); d thickness of layer, (m). the thermal resistance of the layer: wkmdr sl /)(,/ 2 . ⋅= λ (6) where: d – thickness of material, (m); λ – thermal conductivity, (w/(m⋅k). the thermal diffusion of the layer (pupeikis et al. 2010): )/(,/ 2 . kmwd sl ⋅=λ λ (7) where: λ – thermal conductance, (w/m 2 ⋅k); λ – thermal conductivity, (w/(m⋅k)); d – thickness of layer, (m). the thermal diffusivity of the material: sm c a p /; 2 ⋅ = ρ λ (8) where: λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal diffusion of the separate layer: )/1(, 2 s d a a sl = (9) where: a sl – thermal diffusion of the material layer [1/s]; a – thermal diffusivity of material, [m 2 /s]; d – thickness of layer, [m]. the dependence of layer thickness on the fourier number and time step: )(, m f za d o δ⋅ = (10) where: a – thermal diffusivity of material, (m 2 /s); d – thickness of layer, (m); δz the time step, (s); f o fourier number. thermal diffusivity of the material a (m 2 /s; m 2 /h) shows the rate of temperature “diffusion/equalization” in the object, i.e. the part of 1 m distance per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop between two planes (points) at 1 m distance is 1k. the inverse proportion 1/a (s/m 2 ; h/m 2 ) shows the time in which the temperature equalizes between two planes (points) of the homogeneous object at 1 m distance, when the temperature drop at the initial moment is 1k. suppose, there is an eps with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), then, the calculations are performed according to (8) a=0,00000209 m 2 /s≈0,0075m 2 /h and 1/a= 478571 s/m 2 ≈133 h/m 2 . thermal diffusion of the layer a (1/s; 1/h) shows the rate of thermal “diffusion/equalization”, i.e., the part of layer thickness y per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop on both sides of the layer is 1k. the inverse proportion 1/a (s; h) shows the time in which the temperature equalizes in the homogeneous layer, when layer thickness is y and temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), d= 50mm, then, the calculations are performed according to (9): a≈3,01,(1/h) and 1/a≈0,332, (h). fourier number f o shows the thickness (depth) of “equalization” in the layer during the selected time step δz, i.e., the part of layer thickness y for the temperature to equalize in the homogeneous layer from the initial moment during the time period δz, when the temperature drop on both sides of the layer, whose thickness is y, is 1k. (7) where: l – thermal conductance, (w/m2×k); λ – thermal conductivity, (w/(m×k)); d – thickness of layer, (m). the thermal diffusivity of the material: sm c a p /; 2 ⋅ = ρ l (8) where: λ – thermal conductivity, (w/(m×k)); ρ – material density, (kg/m3); c – specific thermal capacity , (j/(kg×k)). the thermal diffusion of the separate layer: where: ν n , ρ n and c n are the volume, density and specific heat, respectively, of element n. thermal regime inside the building is affected in two ways: due to infiltration and through the external building envelope. in reality, most of the buildings are made of enclosures of different construction types, depending on the purpose and technological regime of the building and dominant construction traditions in the country. the massive layer of multi-layered enclosures can be oriented to the exterior or the interior of the building, or it can be in the middle of the enclosure. thermal capacitance is an important quality that enables walls to absorb, store and later release thermal energy into the building space. the aim of this work is to determine the effect of massive layer position in the enclosure on the thermal inertia of the enclosure. 2. methods the accuracy of calculations of unsteady heat transfer using the finite elements method depends on the selected values of fourier and biot numbers. the fourier number is designated by the symbol f o and the equation for every layer of this number is (stankevičius et al. 2000, incropera et al. 2007, hagentoft 2001): 2 d za f o δ⋅ = (3) the fourier number can also be expressed as: ; 2 za c z rc z dc z f sl sl slslp o δ⋅= δ⋅λ = ⋅ δ = ⋅⋅ δ⋅ = ρ λ (4) where: a – the thermal diffusivity, (m 2 /s); δz – the time step, (s); d – thickness of conditional layer, (m); λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal capacitance of the layer: )/(, 2 . kmjdcc psl ⋅⋅⋅= ρ (5) where: ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)); d thickness of layer, (m). the thermal resistance of the layer: wkmdr sl /)(,/ 2 . ⋅= λ (6) where: d – thickness of material, (m); λ – thermal conductivity, (w/(m⋅k). the thermal diffusion of the layer (pupeikis et al. 2010): )/(,/ 2 . kmwd sl ⋅=λ λ (7) where: λ – thermal conductance, (w/m 2 ⋅k); λ – thermal conductivity, (w/(m⋅k)); d – thickness of layer, (m). the thermal diffusivity of the material: sm c a p /; 2 ⋅ = ρ λ (8) where: λ – thermal conductivity, (w/(m⋅k)); ρ – material density, (kg/m 3 ); c – specific thermal capacity , (j/(kg⋅k)). the thermal diffusion of the separate layer: )/1(, 2 s d a a sl = (9) where: a sl – thermal diffusion of the material layer [1/s]; a – thermal diffusivity of material, [m 2 /s]; d – thickness of layer, [m]. the dependence of layer thickness on the fourier number and time step: )(, m f za d o δ⋅ = (10) where: a – thermal diffusivity of material, (m 2 /s); d – thickness of layer, (m); δz the time step, (s); f o fourier number. thermal diffusivity of the material a (m 2 /s; m 2 /h) shows the rate of temperature “diffusion/equalization” in the object, i.e. the part of 1 m distance per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop between two planes (points) at 1 m distance is 1k. the inverse proportion 1/a (s/m 2 ; h/m 2 ) shows the time in which the temperature equalizes between two planes (points) of the homogeneous object at 1 m distance, when the temperature drop at the initial moment is 1k. suppose, there is an eps with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), then, the calculations are performed according to (8) a=0,00000209 m 2 /s≈0,0075m 2 /h and 1/a= 478571 s/m 2 ≈133 h/m 2 . thermal diffusion of the layer a (1/s; 1/h) shows the rate of thermal “diffusion/equalization”, i.e., the part of layer thickness y per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop on both sides of the layer is 1k. the inverse proportion 1/a (s; h) shows the time in which the temperature equalizes in the homogeneous layer, when layer thickness is y and temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), d= 50mm, then, the calculations are performed according to (9): a≈3,01,(1/h) and 1/a≈0,332, (h). fourier number f o shows the thickness (depth) of “equalization” in the layer during the selected time step δz, i.e., the part of layer thickness y for the temperature to equalize in the homogeneous layer from the initial moment during the time period δz, when the temperature drop on both sides of the layer, whose thickness is y, is 1k. (9) where: asl – thermal diffusion of the material layer [1/s]; a – thermal diffusivity of material, [m2/s]; d – thickness of layer, [m]. the dependence of layer thickness on the fourier number and time step: )(, m f za d o d⋅ = (10) where: a – thermal diffusivity of material, (m2/s); d – thickness of layer, (m); dz – the time step, (s); fo – fourier number. thermal diffusivity of the material a (m2/s; m2/h) shows the rate of temperature “diffusion/equalization” in the object, i.e. the part of 1 m distance per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop between two planes (points) at 1 m distance is 1k. the inverse proportion 1/a (s/m2; h/m2) shows the time in which the temperature equalizes between two planes (points) of the homogeneous object at 1 m distance, when the temperature drop at the initial moment is 1k. suppose, there is an eps with the following characteristics: λ = 0,07 w/(m×k); ρ = 25 kg/m3; cp = 1340 j/(kg×k), then, the calculations are performed according to (8) a = 0,00000209 m2/s ≈  0,0075m2/h and 1/a = 478571 s/m2 ≈  133 h/m2. thermal diffusion of the layer a (1/s; 1/h) shows the rate of thermal “diffusion/equalization”, i.e., the part of layer thickness y per time unit for the temperature to equalize in the homogeneous object from the initial moment, when the temperature drop on both sides of the layer is 1k. the inverse proportion 1/a (s; h) shows the time in which the temperature equalizes in the homogeneous layer, when layer thickness is y and temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: l  =  0,07 w/(m×k); ρ = 25 kg/m3; cp = 1340 j/(kg×k), d = 50mm, then, the calculations are performed according to (9): a ≈  3,01,(1/h) and 1/a ≈  0,332, (h). 42 fourier number fo – shows the thickness (depth) of “equalization” in the layer during the selected time step δz, i.e., the part of layer thickness y for the temperature to equalize in the homogeneous layer from the initial moment during the time period δz, when the temperature drop on both sides of the layer, whose thickness is y, is 1k. the inverse proportion 1/fo – shows how much more time it would take, in comparison to the time period δz, for temperature to equalize in the whole homogeneous layer, when the thickness of the layer is y, and the temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ = 0,07 w/(m×k); ρ = 25 kg/m3; cp = 1340 j/(kg×k), d = 50mm, dz = 0,1 h, then, the calculations are performed according to (4): fo ≈  0,301 and 1/fo ≈  3,322. thus, if dz = 0,1×3,322 ≈  0,3322 h, then fo ≈  0,9999 and 1/fo ≈  1,000; in other words, during this time period, the temperature equalizes in all the thickness of the layer. 2dc z zaf p o ⋅⋅ d⋅ =d⋅= ρ l (11) the biot number is usually expressed as: the inverse proportion 1/f o shows how much more time it would take, in comparison to the time period δz, for temperature to equalize in the whole homogeneous layer, when the thickness of the layer is y, and the temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), d= 50mm, δz=0,1 h, then, the calculations are performed according to (4): f o ≈0,301 and 1/f o ≈3,322. thus, if δz=0,1⋅3,322≈0,3322 h, then f o ≈ 0,9999 and 1/f o ≈1,000; in other words, during this time period, the temperature equalizes in all the thickness of the layer. 2 dc z zaf p o ⋅⋅ δ⋅ =δ⋅= ρ λ (11) the biot number is usually expressed as: λ dh bi ⋅ = (12) where: h – surface heat exchange coefficient, d – thickness of the surface layer of the enclosure, λ thermal conductivity coefficient of the surface layer of the material. the biot number can also be expressed in the following way: . .. .. . ... /1 pav slpav slpav pav slpavpav h rh rhbi δ = λ =δ⋅= (13) where: h pav. – surface heat exchange coefficient; δr pav.sl. – thermal resistance of the first surface layer; λ pav.sl. – thermal diffusion of the first surface layer (the inverse proportion of thermal resistance). according to (karbauskaite et al. 2008, hensen 1994), the limit value of the fourier number is equal to 0.5. the values of this number are higher than 0.5 and cause significant errors in temperature calculations. in some cases, the temperature calculation average error increases significantly when the value of the fourier number reaches 0.47 (pupeikis et al. 2012). in case of transient heat transfer, the temperature in any plane of enclosure is determined by the following equation (14) in (fig. 1): ⋅⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ δ θ−θ − δ θ−θ +θ=θ + − − n nn n nn nn rr 1 1 1 ' (14) nnnnnn cdcd z ρρ ⋅⋅+⋅⋅ δ⋅ ⋅ −−− 111 2 it is understood as (15) or (16), ( ) nn nnnnnn z qq χχ + δ⋅ ⋅−+θ=θ − +− 1 /)1()'1/( 2 ' (15) or ( ) = ⋅−+θ=θ −+ +− )1/()1( /)1()'1/( 1 ' nn nnnnnn s qq (16) '/ )1/()1( )1/()1( ' ' nnn nn nn n t s q δ+θ= δ +θ= −+ −+ where: θ’ n – temperature of plane n at the present time moment; δz – time period (calculation time step), (s); d n – thickness of layer between “n“ and “n+1“ planes, (m); c n – specific thermal capacity of layer between “n“ and “n+1“ planes, (j/(kg·k)); ρ n – the material of layer between “n“ and “n+1“ planes density, kg/m 3 ; q’ n’/(n-1) – the potential of heat flow density between “n“ and “n-1“ planes at the time moment after time period δz, (w/m 2 ); q’ (n+1)/n’ – heat flow density between “n“ and “n+1“ planes at the initial time moment z, i.e. the heat flow rate due to temperature difference (θ n – θ n+1 ), w/ m 2 ; χ n-1 ir χ n – coefficient of area thermal capacitance of the layer “n-1” and “n“ , (j/(m 2 ⋅k)); s (n+1)/(n-1) – the average thermal receptivity of the material of both layers “(n-1)“ and “n”, (w/(m 2 ⋅k)); δt n/n‘ – temperature change in the plane “n” after the time period δz passed from the initial time moment. according to (incropera et al. 2007), it is recommended that the first surface layer thickness amounted to ½ of the thickness of other layers, since it is important for obtaining the required biot number. for the calculation of a unidimensional temperature field, when f o is inside the enclosure, the stability criteria is the following: (1-2⋅f o )≥ 0, from here f o ≤ 0,5; when bi is displayed on the surface of the wall, the stability criteria is the following: (1-2⋅f o -2⋅bi⋅f o ) ≥ 0, from here f o ⋅ (1+bi) ≤ 0,5. the second criterion with bi is more sensitive than the first one; therefore, it has to be used for determining the critical (the largest allowed) calculation time step δz: the positive bi ≤ 0,1 is preferred. the maximum allowed f o is determined applying: bi f o + ≤ 1 5,0 (17) using the maximum allowed f o , the maximum allowed time step is calculated: a df z o 2 ⋅ ≤δ (18) the finite elements difference explicit method is used for calculating new values using the already know ones. (12) where: h – surface heat exchange coefficient, d – thickness of the surface layer of the enclosure, λ – thermal conductivity coefficient of the surface layer of the material. the biot number can also be expressed in the following way: the inverse proportion 1/f o shows how much more time it would take, in comparison to the time period δz, for temperature to equalize in the whole homogeneous layer, when the thickness of the layer is y, and the temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), d= 50mm, δz=0,1 h, then, the calculations are performed according to (4): f o ≈0,301 and 1/f o ≈3,322. thus, if δz=0,1⋅3,322≈0,3322 h, then f o ≈ 0,9999 and 1/f o ≈1,000; in other words, during this time period, the temperature equalizes in all the thickness of the layer. 2 dc z zaf p o ⋅⋅ δ⋅ =δ⋅= ρ λ (11) the biot number is usually expressed as: λ dh bi ⋅ = (12) where: h – surface heat exchange coefficient, d – thickness of the surface layer of the enclosure, λ thermal conductivity coefficient of the surface layer of the material. the biot number can also be expressed in the following way: . .. .. . ... /1 pav slpav slpav pav slpavpav h rh rhbi δ = λ =δ⋅= (13) where: h pav. – surface heat exchange coefficient; δr pav.sl. – thermal resistance of the first surface layer; λ pav.sl. – thermal diffusion of the first surface layer (the inverse proportion of thermal resistance). according to (karbauskaite et al. 2008, hensen 1994), the limit value of the fourier number is equal to 0.5. the values of this number are higher than 0.5 and cause significant errors in temperature calculations. in some cases, the temperature calculation average error increases significantly when the value of the fourier number reaches 0.47 (pupeikis et al. 2012). in case of transient heat transfer, the temperature in any plane of enclosure is determined by the following equation (14) in (fig. 1): ⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ δ θ−θ − δ θ−θ +θ=θ + − − n nn n nn nn rr 1 1 1 ' (14) nnnnnn c d c d z ρρ ⋅⋅+⋅⋅ δ⋅ ⋅ −−− 111 2 it is understood as (15) or (16), ( ) nn nnnnnn z qq χχ + δ⋅ ⋅−+θ=θ − +− 1 /)1()'1/( 2 ' (15) or ( ) = ⋅−+θ=θ −+ +− )1/()1( /)1()'1/( 1 ' nn nnnnnn s qq (16) '/ )1/()1( )1/()1( ' ' nnn nn nn n t s q δ+θ= δ +θ= −+ −+ where: θ’ n – temperature of plane n at the present time moment; δz – time period (calculation time step), (s); d n – thickness of layer between “n“ and “n+1“ planes, (m); c n – specific thermal capacity of layer between “n“ and “n+1“ planes, (j/(kg·k)); ρ n – the material of layer between “n“ and “n+1“ planes density, kg/m 3 ; q’ n’/(n-1) – the potential of heat flow density between “n“ and “n-1“ planes at the time moment after time period δz, (w/m 2 ); q’ (n+1)/n’ – heat flow density between “n“ and “n+1“ planes at the initial time moment z, i.e. the heat flow rate due to temperature difference (θ n – θ n+1 ), w/ m 2 ; χ n-1 ir χ n – coefficient of area thermal capacitance of the layer “n-1” and “n“ , (j/(m 2 ⋅k)); s (n+1)/(n-1) – the average thermal receptivity of the material of both layers “(n-1)“ and “n”, (w/(m 2 ⋅k)); δt n/n‘ – temperature change in the plane “n” after the time period δz passed from the initial time moment. according to (incropera et al. 2007), it is recommended that the first surface layer thickness amounted to ½ of the thickness of other layers, since it is important for obtaining the required biot number. for the calculation of a unidimensional temperature field, when f o is inside the enclosure, the stability criteria is the following: (1-2⋅f o )≥ 0, from here f o ≤ 0,5; when bi is displayed on the surface of the wall, the stability criteria is the following: (1-2⋅f o -2⋅bi⋅f o ) ≥ 0, from here f o ⋅ (1+bi) ≤ 0,5. the second criterion with bi is more sensitive than the first one; therefore, it has to be used for determining the critical (the largest allowed) calculation time step δz: the positive bi ≤ 0,1 is preferred. the maximum allowed f o is determined applying: bi f o + ≤ 1 5,0 (17) using the maximum allowed f o , the maximum allowed time step is calculated: a df z o 2 ⋅ ≤δ (18) the finite elements difference explicit method is used for calculating new values using the already know ones. (13) where: hpav. – surface heat exchange coefficient; drpav.sl. – thermal resistance of the first surface layer; lpav.sl. – thermal diffusion of the first surface layer (the inverse proportion of thermal resistance). according to (karbauskaite et al. 2008, hensen 1994), the limit value of the fourier number is equal to 0.5. the values of this number are higher than 0.5 and cause significant errors in temperature calculations. in some cases, the temperature calculation average error increases significantly when the value of the fourier number reaches 0.47 (pupeikis et al. 2012). in case of transient heat transfer, the temperature in any plane of enclosure is determined by the following equation (14) in (fig. 1): ⋅        d θ−θ − d θ−θ +θ=θ + − − n nn n nn nn rr 1 1 1' (14) nnnnnn cdcd z ρρ ⋅⋅+⋅⋅ d⋅ ⋅ −−− 111 2 it is understood as (15) or (16), ( ) nn nnnnnn z qq cc + d⋅ ⋅−+θ=θ − +− 1 /)1()'1/( 2 ' (15) or ( ) =⋅−+θ=θ −+ +− )1/()1( /)1()'1/( 1 ' nn nnnnnn s qq (16) '/ )1/()1( )1/()1( ' ' nnn nn nn n ts q d+θ= d +θ= −+ −+ where: θ'n – temperature of plane n at the present time moment; δz – time period (calculation time step), (s); dn – thickness of layer between “n“ and “n + 1“ planes, (m); cn – specific thermal capacity of layer between “n“ and “n + 1“ planes, (j/(kg·k)); ρn – the material of layer between “n“ and “n + 1“ planes density, kg/m3; q'n'/(n–1) – the potential of heat flow density between “n“ and “n – 1“ planes at the time moment after time period δz, (w/m2); q'(n+1)/n' – heat flow density between “n“ and “n + 1“ planes at the initial time moment z, i.e. the heat flow rate due to temperature difference (θn – θn+1), w/ m2; cn –1 ir cn – coefficient of area thermal capacitance of the layer “n – 1” and “n“, (j/(m2×k)); s(n+1)/(n-1) – the average thermal receptivity of the material of both layers “(n – 1)“ and “n”, (w/(m2×k)); dtn/n' – temperature change in the plane “n” after the time period δz passed from the initial time moment. fig. 1. principle scheme for calculating the interlayer temperature of the enclosure 3. materials and equipment two building models were made for the experiments. heat transfer coefficient of the internal surface of the enclosures of models wm-i and wm-ii, which describes the surface heat exchange of the enclosure with the environment, is the following: )/(, 1 11 2 4 2 21 3 kmw tt s nuh airs s −+ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + ⋅⋅ +⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⋅= εε σ λ (19) where: σ =5.6704·10 -8 – stefan–boltzmann constant, (w⋅m 2 ⋅k -4 ); s – thickness of air boundary layer, (m); nu – nusselt number calculated according to lst en 673:2011; λ thermal conductivity of still air, w/(m·k); t s – temperature of the surface, (k); t air – surround air temperature, (k); ε 1 – emissivity of surface; ε 2 – emissivity of surrounding. the measured thermal properties of materials used in wall models wm-i and wm-ii are presented in (table 1). the thermal conductivity values of the materials were measured according to (lst en 12667:2002, stankevičius et al. 2005) in lambda apparatus which meets the requirements of (iso 8301:1991). the density of materials was determined in accordance with (lst en 1602: 1998, lst en 1602: 1998/ac:2003). the thermal capacitance values of common construction materials used in the experiment were selected from literature sources in accordance to the type and density of the materials. both models wm-i and wm-ii were made of materials commonly used in practice (fig. 2). five walls of the model 600x600x600 mm ( length x width x height ) were made of polystyrene (eps) boards d 1 =50+50mm. heterogeneous enclosure of the models consists of two medium density wood fibre boards (mdf), with the thickness of d 2 =18+18mm, and one expanded polystyrene (eps) board, d 1 =50mm. internal and external volumes of the models are identical, but the position of mdf massive layer in heterogeneous enclosures is different: in wm-i, it is oriented to the interior, and in wm-ii, it is oriented to the exterior. eps d1=(50+50)mm eps d1=50mm mdf d2=18+18mm eps d1=(50+50)mm eps d1=(50+50)mm eps d1=(50+50)mm eps d1=(50+50)mm mdfd2=18+18mm eps d1=50mm eps d1=(50+50)mm t7 t8 t9 t25 t11 t1 t2 t5 t3 t4 t10 wm-ii wm-i fig. 2. structural scheme of thermocouple arrangement and models. tthermocouples fig. 1. principle scheme for calculating the interlayer temperature of the enclosure according to (incropera et al. 2007), it is recommended that the first surface layer thickness amounted to ½ of the thickness of other layers, since it is important for obtaining the required biot number. for the calculation of a unidimensional temperature field, when fo is inside the enclosure, the stability criteria is the following: (1–2·fo) ≥ 0, from here fo ≤ 0,5; when bi is displayed on the surface of the wall, the stability criteria is the following: (1–2 · fo – 2 · bi · fo) ≥ 0, from here fo·(1+bi) ≤ 0,5. the second criterion with bi is more sensitive than the first one; therefore, it has to be used for determining the critical (the largest allowed) calculation time step δz: 43 the positive bi ≤ 0,1 is preferred. the maximum allowed fo is determined applying: the inverse proportion 1/f o shows how much more time it would take, in comparison to the time period δz, for temperature to equalize in the whole homogeneous layer, when the thickness of the layer is y, and the temperature drop in the layer at the initial moment is 1k. suppose, there is an eps layer with the following characteristics: λ=0,07 w/(m⋅k); ρ=25 kg/m 3 ; c p =1340 j/(kg⋅k), d= 50mm, δz=0,1 h, then, the calculations are performed according to (4): f o ≈0,301 and 1/f o ≈3,322. thus, if δz=0,1⋅3,322≈0,3322 h, then f o ≈ 0,9999 and 1/f o ≈1,000; in other words, during this time period, the temperature equalizes in all the thickness of the layer. 2 dc z zaf p o ⋅⋅ δ⋅ =δ⋅= ρ λ (11) the biot number is usually expressed as: λ dh bi ⋅ = (12) where: h – surface heat exchange coefficient, d – thickness of the surface layer of the enclosure, λ thermal conductivity coefficient of the surface layer of the material. the biot number can also be expressed in the following way: . .. .. . ... /1 pav slpav slpav pav slpavpav h rh rhbi δ = λ =δ⋅= (13) where: h pav. – surface heat exchange coefficient; δr pav.sl. – thermal resistance of the first surface layer; λ pav.sl. – thermal diffusion of the first surface layer (the inverse proportion of thermal resistance). according to (karbauskaite et al. 2008, hensen 1994), the limit value of the fourier number is equal to 0.5. the values of this number are higher than 0.5 and cause significant errors in temperature calculations. in some cases, the temperature calculation average error increases significantly when the value of the fourier number reaches 0.47 (pupeikis et al. 2012). in case of transient heat transfer, the temperature in any plane of enclosure is determined by the following equation (14) in (fig. 1): ⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ δ θ−θ − δ θ−θ +θ=θ + − − n nn n nn nn rr 1 1 1 ' (14) nnnnnn cdcd z ρρ ⋅⋅+⋅⋅ δ⋅ ⋅ −−− 111 2 it is understood as (15) or (16), ( ) nn nnnnnn z qq χχ + δ⋅ ⋅−+θ=θ − +− 1 /)1()'1/( 2 ' (15) or ( ) =⋅−+θ=θ −+ +− )1/()1( /)1()'1/( 1 ' nn nnnnnn s qq (16) '/ )1/()1( )1/()1( ' ' nnn nn nn n t s q δ+θ= δ +θ= −+ −+ where: θ’ n – temperature of plane n at the present time moment; δz – time period (calculation time step), (s); d n – thickness of layer between “n“ and “n+1“ planes, (m); c n – specific thermal capacity of layer between “n“ and “n+1“ planes, (j/(kg·k)); ρ n – the material of layer between “n“ and “n+1“ planes density, kg/m 3 ; q’ n’/(n-1) – the potential of heat flow density between “n“ and “n-1“ planes at the time moment after time period δz, (w/m 2 ); q’ (n+1)/n’ – heat flow density between “n“ and “n+1“ planes at the initial time moment z, i.e. the heat flow rate due to temperature difference (θ n – θ n+1 ), w/ m 2 ; χ n-1 ir χ n – coefficient of area thermal capacitance of the layer “n-1” and “n“ , (j/(m 2 ⋅k)); s (n+1)/(n-1) – the average thermal receptivity of the material of both layers “(n-1)“ and “n”, (w/(m 2 ⋅k)); δt n/n‘ – temperature change in the plane “n” after the time period δz passed from the initial time moment. according to (incropera et al. 2007), it is recommended that the first surface layer thickness amounted to ½ of the thickness of other layers, since it is important for obtaining the required biot number. for the calculation of a unidimensional temperature field, when f o is inside the enclosure, the stability criteria is the following: (1-2⋅f o )≥ 0, from here f o ≤ 0,5; when bi is displayed on the surface of the wall, the stability criteria is the following: (1-2⋅f o -2⋅bi⋅f o ) ≥ 0, from here f o ⋅ (1+bi) ≤ 0,5. the second criterion with bi is more sensitive than the first one; therefore, it has to be used for determining the critical (the largest allowed) calculation time step δz: the positive bi ≤ 0,1 is preferred. the maximum allowed f o is determined applying: bi f o + ≤ 1 5,0 (17) using the maximum allowed f o , the maximum allowed time step is calculated: a df z o 2 ⋅ ≤δ (18) the finite elements difference explicit method is used for calculating new values using the already know ones. (17) using the maximum allowed fo , the maximum allowed time step is calculated: a df z o 2⋅ ≤d (18) the finite elements difference explicit method is used for calculating new values using the already know ones. 3. materials and equipment two building models were made for the experiments. heat transfer coefficient of the internal surface of the enclosures of models wm-i and wm-ii, which describes the surface heat exchange of the enclosure with the environment, is the following: fig. 1. principle scheme for calculating the interlayer temperature of the enclosure 3. materials and equipment two building models were made for the experiments. heat transfer coefficient of the internal surface of the enclosures of models wm-i and wm-ii, which describes the surface heat exchange of the enclosure with the environment, is the following: )/(, 1 11 2 4 2 21 3 kmw tt s nuh airs s −+ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + ⋅⋅ +⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⋅= εε σ λ (19) where: σ =5.6704·10 -8 – stefan–boltzmann constant, (w⋅m 2 ⋅k -4 ); s – thickness of air boundary layer, (m); nu – nusselt number calculated according to lst en 673:2011; λ thermal conductivity of still air, w/(m·k); t s – temperature of the surface, (k); t air – surround air temperature, (k); ε 1 – emissivity of surface; ε 2 – emissivity of surrounding. the measured thermal properties of materials used in wall models wm-i and wm-ii are presented in (table 1). the thermal conductivity values of the materials were measured according to (lst en 12667:2002, stankevičius et al. 2005) in lambda apparatus which meets the requirements of (iso 8301:1991). the density of materials was determined in accordance with (lst en 1602: 1998, lst en 1602: 1998/ac:2003). the thermal capacitance values of common construction materials used in the experiment were selected from literature sources in accordance to the type and density of the materials. both models wm-i and wm-ii were made of materials commonly used in practice (fig. 2). five walls of the model 600x600x600 mm ( length x width x height ) were made of polystyrene (eps) boards d 1 =50+50mm. heterogeneous enclosure of the models consists of two medium density wood fibre boards (mdf), with the thickness of d 2 =18+18mm, and one expanded polystyrene (eps) board, d 1 =50mm. internal and external volumes of the models are identical, but the position of mdf massive layer in heterogeneous enclosures is different: in wm-i, it is oriented to the interior, and in wm-ii, it is oriented to the exterior. eps d1=(50+50)mm eps d1=(50+50)mm eps d1=(50+50)mm eps d1=(50+50)mm eps d1=(50+50)mm mdfd2=18+18mm eps d1=50mm eps d1=(50+50)mm t7 t8 t9 t11 t1 t2 t5 t3 t4 t10 wm-ii wm-i fig. 2. structural scheme of thermocouple arrangement and models. tthermocouples (19) where: σ = 5.6704·10-8 – stefan–boltzmann constant, (w×m-2×k-4); s – thickness of air boundary layer, (m); λ – thermal conductivity of still air, w/(m∙k); ts – temperature of the surface, (k); tair – surround air temperature, (k); ε1 – emissivity of surface; ε2 – emissivity of surrounding. the measured thermal properties of materials used in wall models wm-i and wm-ii are presented in (table 1). the thermal conductivity values of the materials were measured according to (lst en 12667:2002, stankevičius et al. 2005) in lambda apparatus which meets the requirements of (iso 8301:1991). the density of materials was determined in accordance with (lst en 1602: 1998, lst en 1602: 1998/ac:2003). fig. 1. principle scheme for calculating the interlayer temperature of the enclosure 3. materials and equipment two building models were made for the experiments. heat transfer coefficient of the internal surface of the enclosures of models wm-i and wm-ii, which describes the surface heat exchange of the enclosure with the environment, is the following: )/(, 1 11 2 4 2 21 3 kmw tt s nuh airs s −+ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + ⋅⋅ +⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⋅= εε σ λ (19) where: σ =5.6704·10 -8 – stefan–boltzmann constant, (w⋅m 2 ⋅k -4 ); s – thickness of air boundary layer, (m); nu – nusselt number calculated according to lst en 673:2011; λ thermal conductivity of still air, w/(m·k); t s – temperature of the surface, (k); t air – surround air temperature, (k); ε 1 – emissivity of surface; ε 2 – emissivity of surrounding. the measured thermal properties of materials used in wall models wm-i and wm-ii are presented in (table 1). the thermal conductivity values of the materials were measured according to (lst en 12667:2002, stankevičius et al. 2005) in lambda apparatus which meets the requirements of (iso 8301:1991). the density of materials was determined in accordance with (lst en 1602: 1998, lst en 1602: 1998/ac:2003). the thermal capacitance values of common construction materials used in the experiment were selected from literature sources in accordance to the type and density of the materials. both models wm-i and wm-ii were made of materials commonly used in practice (fig. 2). five walls were made of polystyrene (eps) boards d 1 =50+50mm. heterogeneous enclosure of the models consists of two medium density wood fibre boards (mdf), with the thickness of d 2 =18+18mm, and one expanded polystyrene (eps) board, d 1 =50mm. internal and external volumes of the models are identical, but the position of mdf massive layer in heterogeneous enclosures is different: in wm-i, it is oriented to the interior, and in wm-ii, it is oriented to the exterior. eps d1=(50+50)mm eps d1=50mm mdf d2=18+18mm eps d1=(50+50)mm eps d1=(50+50)mm eps d1=(50+50)mm eps d1=(50+50)mm mdfd2=18+18mm eps d1=50mm eps d1=(50+50)mm t7 t8 t9 t25 t11 t1 t2 t5 t3 t4 t10 wm-ii wm-i fig. 2. structural scheme of thermocouple arrangement and models. tthermocouples fig. 2. structural scheme of thermocouple arrangement and models. tthermocouples table 1. the walls studied: wm-i and wm-ii with the same values of thermal transmittance u, but with different values of internal areal thermal capacity walls model wm-i wm-ii thickness, (mm) 50.0 + 36.0 = 86.0 36.0 + 50.0 = 86.0 insulation (eps expanded polystyrene) conductivity λ, (w/m·k) 0.039 0,039 density ρ, (kg/m³) 15.807 15.807 thermal capacity c, (j/kg·k) 1450 1450 mass (mdf – medium density wood fibreboard) conductivity λ, (w/m·k) 0.12 0.12 density ρ, (kg/m³) 787.22 787.22 thermal capacity c, (j/kg·k) 1430 1430 thermal transmittance uwall, (w/(m2∙k) 0.57 0.57 nu – nusselt number calculated according to lst en 673:2011; 44 the thermal capacitance values of common construction materials used in the experiment were selected from literature sources in accordance to the type and density of the materials. both models wm-i and wm-ii were made of materials commonly used in practice (fig. 2). five walls of the model 600 x 600 x 600 mm (length x width x height) were made of polystyrene (eps) boards d1 = 50 + 50 mm. heterogeneous enclosure of the models consists of two medium density wood fibre boards (mdf), with the thickness of d2 = 18 + 18 mm, and one expanded polystyrene (eps) board, d1 = 50mm. internal and external volumes of the models are identical, but the position of mdf massive layer in heterogeneous enclosures is different: in wm-i, it is oriented to the interior, and in wm-ii, it is oriented to the exterior. 4. experimental and results in order to determine the accuracy of the calculation method, the experiment was carried out. on the basis of the experiment, the calculation program was created for the evaluation of unsteady heat exchange in multi-layered enclosures (using ms excel). in conditional layers of the enclosure, temperature fluctuations are calculated using finite elements method, and the values of internal enclosure layers are estimated according to the equations given in chapter 2. the experiment was carried out by imitating climatic conditions in the climatic test chamber, in the laboratory of building thermal physics at institute of architecture and construction of kaunas university of technology, (ktu asi). two spatial models, differing in the position of their high thermal resistance layer, i.e. inside and outside of the model, were constructed in the chamber. the aim of the experiment was to change the temperature of the surroundings by cooling and heating it and observe temperature changes in the walls and the interior of the models. in order to ensure the accuracy of the experiment, the values of thermal parameters of the materials were determined and the thermocouples measuring the temperature were calibrated. during the experiment, the temperature was measured every one second and the average of one minute was recorded (one minute time step is also acceptable in calculations). data accumulator dl-3 scanned the values of automatically measured temperatures, recorded them and presented in ms excel format. during the experiment, the dynamic temperature oscillation consisting of seven cooling and heating cycles was created in the climatic chamber using cooling and heating devices. before the experiment, steady temperature of θi = +18.56 ºc was settled in the climatic chamber and inside the models wm-i and wm-ii. dispersion limits of the thermocouples (t1...t25) were the following: ae = ± 0.25 ºc. the experiment begins with the cooling cycle, which lasts for three hours. the temperature inside the climatic chamber is lowered down to θe = (–20) ºc. when this cycle is over, a two-hour heating cycle begins and the temperature raises up to θe = (+25) ºc. the temperature oscillation amplitude is equal to ae = (+25 ºc)÷(–20 ºc). using the outdoor air temperature oscillation data obtained during the experiment, calculations were performed in order to determine the temperature of the indoor air and wall interlayers. the temperatures were compared with the values measured during the experiment. the accuracy of the calculations in the nonhomogeneous (multi-layered) enclosure depends on the fourier number, which defines the conditions of gradual change and the selection of the rational number of conditional layers. when there is a significant difference among the fourier number values of different layers in multi-layered enclosure fomdf = 0.710 and foeps = 0.398, the temperature distribution dotted curve obtained using the calculation program does not correlate with the experimental data bolded solid curve (fig. 3). -25 -20 -15 -10 -5 0 5 10 15 20 25 1 501 1001 1501 2001 2501 time, [min] te m pe ra tu re , [ °c ] calculated, θis measured, θis fig. 3. correlation of experimental temperature value of the internal surface of multi-layered enclosures of wm-i model with temperature values obtained using the calculation program, when fomdf = 0.710; foeps = 0.398 thus, the experiment clearly shows that the least distorted calculation results were obtained when the layers of multi-layered enclosure made of different materials were divided into rational layers so the values of the fourier number were closely equal. in case of the experimental calculation, the values were fomdf = 0.177 and foeps = 0.1633. the dotted curve, representing the distribution of the temperature calculated using the calculation program, completely correlates with the bolded solid curve representing the experimental data in (fig. 4). -25 -20 -15 -10 -5 0 5 10 15 20 25 1 501 1001 1501 2001 2501 time, [min] te m pe ra tu re , [ °c ] calculated, θis measured, θis fig. 4. correlation of experimental temperature value of the internal surface of multi-layered enclosures of wm-i model with temperature values obtained using the calculation program, when fomdf = 0.177; foeps = 0.1633 45 the calculation program is sufficiently accurate for carrying out further research. 5. the effect of wall‘s massive layer position on time delay, decrement factor and inside temperature time delay and decrement factor are very important factors for the evaluation of thermal resistance of the material. the outdoor air temperature changes chaotically during a 24-h period (bruzgevičius et al. 2012) and influences the microclimate of the premises. building enclosures work as a passive microclimate system and reduces the effect of the outdoor air temperature on the microclimate of the premises. the thermal inertia properties of the enclosures help to reduce energy consumption for ensuring microclimate comfort in the premises during the hot or cold season. many construction types of building enclosures are applied in practice. the outdoor air temperature wave diffuses through building envelope constructions with different time delay due to the inertia properties of the building envelope. the time delay of temperature fluctuation the premises caused by outdoor air temperature fluctuations depends on the thermal inertia of enclosures. the temperature oscillation is assumed to show sinusoidal variations during a 24-h period. time delay φ is defined as (20): min,min,min ei θθ θ−θ=φ (20) max,max,max ei θθ θ−θ=φ (21) the proportion of the amplitudes of the indoor and outdoor air temperature is called the wave decrement factor, which is expressed by the following equation (cibse guide 1988, kontoleon et. al. 2005) as (22): min,max, min,max, ee ii e i a a f θ−θ θ−θ == (22) where: ae – amplitude of outdoor air temperature oscillation, (oc); ai – amplitude of indoor air temperature oscillation, (oc); θe,max – maximum outdoor air temperature, (oc); θe,min – minimum outdoor air temperature, (oc); θi,max – maximum indoor air temperature, (oc); θi,min – minimum indoor air temperature, (oc) these thermal inertia parameters are ilustrated in figure 5. under natural conditions, the outdoor air temperature is influenced by a number of factors: solar radiation, cloudiness, heat absorption and reflection of the ground surface, wind speed, atmospheric pressure and many other (rimkus et. al. 2007). all these factors, their values and combinations influence the fluctuation of the outdoor air temperature. in this research, only the influence of the outdoor air temperature is analysed. in simple cases of the outdoor air temperature forecast, it is assumed that temperature oscillates regularly around its average value according to a cosinusoid. according to this method, the air temperature θd after the time period t is expressed as (phokin 2006): ), ( 2 cos ct t a oead       ⋅⋅+θ=θ π (23) where: θd – average outdoor temperature, (k); ae – amplitude of outdoor temperature oscillation, (k); t – period of temperature oscillation, (h); t – time from the beginning of oscillation, (h). 6. discussion and analysis three structural types of wall insulation have been taken for investigation of time delay and decrement factor (table 2). in wall wm-i the insulation is positioned outdoors; in wm-ii the insulation is positioned indoors; the wm-iii is a single-layer eps insulation. in all three types wall the thermal transmittance is the same (uwall = 0.57 w/(m2∙k)). the temperature values inside these walls are calculated according to the equations given in chapter 2. the outdoor temperature oscillation curves, given in fig. 6 are used for simulation of walls wm-i, wm-ii and wm-iii. periods of outdoor temperature oscillation varies from 0.5 to 10 hours from (a) to (f) (fig. 6). -25 -20 -15 -10 -5 0 5 10 15 20 25 1 501 1001 1501 2001 2501 time, [min] t e m p e r a t u r e , [ ° c ] calculated, θis measured, θis fig. 4. correlation of experimental temperature value of the internal surface of multi-layered enclosures of wm-i model with temperature values obtained using the calculation program, when f omdf =0.177;f oeps =0.1633 the calculation program is sufficiently accurate for carrying out further research. 4. the effect of wall‘s massive layer position on time delay, decrement factor and inside temperature time delay and decrement factor are very important factors for the evaluation of thermal resistance of the material. the outdoor air temperature changes chaotically during a 24-h period (bruzgevičius et al. 2012) and influences the microclimate of the premises. building enclosures work as a passive microclimate system and reduces the effect of the outdoor air temperature on the microclimate of the premises. the thermal inertia properties of the enclosures help to reduce energy consumption for ensuring microclimate comfort in the premises during the hot or cold season. many construction types of building enclosures are applied in practice. the outdoor air temperature wave diffuses through building envelope constructions with different time delay due to the inertia properties of the building envelope. the time delay of temperature fluctuation the premises caused by outdoor air temperature fluctuations depends on the thermal inertia of enclosures. the temperature oscillation is assumed to show sinusoidal variations during a 24-h period. time delay φ is defined as (20): min,min,min ei θθ θ−θ=φ (20) max,max,max ei θθ θ−θ=φ (21) the proportion of the amplitudes of the indoor and outdoor air temperature is called the wave decrement factor, which is expressed by the following equation (cibse guide 1988, kontoleon et. al. 2005) as (22): min,max, min,max, ee ii e i a a f θ−θ θ−θ == (22) where: a e – amplitude of outdoor air temperature oscillation, ( o c); a i – amplitude of indoor air temperature oscillation, ( o c); θ e,max – maximum outdoor air temperature, ( o c); θ e,min – minimum outdoor air temperature, ( o c); θ i,max – maximum indoor air temperature, ( o c); θ i,min – minimum indoor air temperature, ( o c); these thermal inertia parameters are ilustrated in figure 5. under natural conditions, the outdoor air temperature is influenced by a number of factors: solar radiation, cloudiness, heat absorption and reflection of the ground surface, wind speed, atmospheric pressure and many other (rimkus et. al. 2007). all these factors, their values and combinations influence the fluctuation of the outdoor air temperature. in this research, only the influence of the outdoor air temperature is analysed. in simple cases of the outdoor air temperature forecast, it is assumed that temperature oscillates regularly around its average value according to a cosinusoid. according to this method, the air temperature θ d after the time period t is expressed as (phokin 2006): ),( 2 cos ct t a o ead ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⋅⋅+θ=θ π (23) where: θd – average outdoor temperature, (k); ae – amplitude of outdoor temperature oscillation, (k); t – period of temperature oscillation, (h); t – time from the fig. 5. scheme of time delay and decrement factor fig. 5. scheme of time delay and decrement factor . 46 table 2. the walls studied: wm-i, wm-ii, wm-iii with the same values of thermal transmittance u wall models wm-i wm-ii wm-iii 5. discussion and analysis three structural types of wall insulation have been taken for investigation of time delay and decrement factor (table 2). in wall wm-i the insulation is positioned outdoors; in wm-ii the insulation is positioned indoors; the wm-iii is a single-layer eps insulation. in all three types wall the thermal transmittance is the same (u wall = 0.57 w/(m 2 ·k)). the temperature values inside these walls are calculated according to the equations given in chapter 2. the outdoor temperature oscillation curves, given in fig. 6 are used for simulation of walls wm-i, wm-ii and wm-iii. periods of outdoor temperature oscillation varies from 0.5 to 10 hours from (a) to (f) (fig. 6). table 2. the walls studied: wm-i, wm-ii, wm-iii with the same values of thermal transmittance u wall models thickness, (mm) 50.0+36.0=86.0 36.0+50.0=86.0 61.7 insulation (eps expanded polystyrene) conductivity λ, (w/m·k) 0.039 0.039 0.039 density ρ, (kg/m³) 15.807 15.807 15.807 thermal capacity c, (j/kg·k) 1450 1450 1450 mass (mdf – medium density wood fibreboard) conductivity λ, (w/m·k) 0.12 0.12 density ρ, (kg/m³) 787.22 787.22 thermal capacity c, (j/kg·k) 1430 1430 thermal transmittance u wall , w/(m 2 ·k) 0.57 0.57 0.57 period of temperature oscillation time delay, φ (h) 0,5 14 14 11 1 22 21 20 2 33 31 29 4 48 47 42 5 51 51 46 10 68 68 53 period of temperature oscillation decrement factor, f (–) 0,5 0.037 0.037 0.053 1 0.120 0.120 0.160 2 0.273 0.264 0.356 4 0.483 0.483 0.624 5 0.552 0.552 0.709 10 0.739 0.739 0.894 a) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 0.5 [h] t e m p e r a t u r e , [ ° c ] θe θi b) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 1 [h] t e m p e r a t u r e , [ ° c ] θe θi o n l y i n s u l a t i o n e x t e r n a l e s i d e m a s s i n s u l a t i o n e x t e r n a l e s i d e m a s s in s u l a t i o n e x t e r n a l e s i d e 5. discussion and analysis three structural types of wall insulation have been taken for investigation of time delay and decrement factor (table 2). in wall wm-i the insulation is positioned outdoors; in wm-ii the insulation is positioned indoors; the wm-iii is a single-layer eps insulation. in all three types wall the thermal transmittance is the same (u wall = 0.57 w/(m 2 ·k)). the temperature values inside these walls are calculated according to the equations given in chapter 2. the outdoor temperature oscillation curves, given in fig. 6 are used for simulation of walls wm-i, wm-ii and wm-iii. periods of outdoor temperature oscillation varies from 0.5 to 10 hours from (a) to (f) (fig. 6). table 2. the walls studied: wm-i, wm-ii, wm-iii with the same values of thermal transmittance u wall models wm-i wm-ii wm-iii thickness, (mm) 50.0+36.0=86.0 36.0+50.0=86.0 61.7 insulation (eps expanded polystyrene) conductivity λ, (w/m·k) 0.039 0.039 0.039 density ρ, (kg/m³) 15.807 15.807 15.807 thermal capacity c, (j/kg·k) 1450 1450 1450 mass (mdf – medium density wood fibreboard) conductivity λ, (w/m·k) 0.12 0.12 density ρ, (kg/m³) 787.22 787.22 thermal capacity c, (j/kg·k) 1430 1430 thermal transmittance u wall , w/(m 2 ·k) 0.57 0.57 0.57 period of temperature oscillation time delay, φ (h) 0,5 14 14 11 1 22 21 20 2 33 31 29 4 48 47 42 5 51 51 46 10 68 68 53 period of temperature oscillation decrement factor, f (–) 0,5 0.037 0.037 0.053 1 0.120 0.120 0.160 2 0.273 0.264 0.356 4 0.483 0.483 0.624 5 0.552 0.552 0.709 10 0.739 0.739 0.894 a) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 0.5 [h] t e m p e r a t u r e , [ ° c ] θe θi b) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 1 [h] t e m p e r a t u r e , [ ° c ] θe θi o n l y i n s u l a t i o n e x t e r n a l e s i d e m a s s i n s u l a t i o n e x t e r n a l e s i d e m a s s in s u l a t i o n e x t e r n a l e s i d e 5. discussion and analysis three structural types of wall insulation have been taken for investigation of time delay and decrement factor (table 2). in wall wm-i the insulation is positioned outdoors; in wm-ii the insulation is positioned indoors; the wm-iii is a single-layer eps insulation. in all three types wall the thermal transmittance is the same (u wall = 0.57 w/(m 2 ·k)). the temperature values inside these walls are calculated according to the equations given in chapter 2. the outdoor temperature oscillation curves, given in fig. 6 are used for simulation of walls wm-i, wm-ii and wm-iii. periods of outdoor temperature oscillation varies from 0.5 to 10 hours from (a) to (f) (fig. 6). table 2. the walls studied: wm-i, wm-ii, wm-iii with the same values of thermal transmittance u wall models wm-i wm-ii wm-iii thickness, (mm) 50.0+36.0=86.0 36.0+50.0=86.0 61.7 insulation (eps expanded polystyrene) conductivity λ, (w/m·k) 0.039 0.039 0.039 density ρ, (kg/m³) 15.807 15.807 15.807 thermal capacity c, (j/kg·k) 1450 1450 1450 mass (mdf – medium density wood fibreboard) conductivity λ, (w/m·k) 0.12 0.12 density ρ, (kg/m³) 787.22 787.22 thermal capacity c, (j/kg·k) 1430 1430 thermal transmittance u wall , w/(m 2 ·k) 0.57 0.57 0.57 period of temperature oscillation time delay, φ (h) 0,5 14 14 11 1 22 21 20 2 33 31 29 4 48 47 42 5 51 51 46 10 68 68 53 period of temperature oscillation decrement factor, f (–) 0,5 0.037 0.037 0.053 1 0.120 0.120 0.160 2 0.273 0.264 0.356 4 0.483 0.483 0.624 5 0.552 0.552 0.709 10 0.739 0.739 0.894 a) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 0.5 [h] t e m p e r a t u r e , [ ° c ] θe θi b) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 1 [h] t e m p e r a t u r e , [ ° c ] θe θi o n l y i n s u l a t i o n e x t e r n a l e s i d e m a s s i n s u l a t i o n e x t e r n a l e s i d e m a s s in s u l a t i o n e x t e r n a l e s i d e thickness, (mm) 50.0 + 36.0 = 86.0 36.0 + 50.0 = 86.0 61.7 insulation (eps expanded polystyrene) conductivity λ, (w/m·k) 0.039 0.039 0.039 density ρ, (kg/m³) 15.807 15.807 15.807 thermal capacity c, (j/kg·k) 1450 1450 1450 mass (mdf – medium density wood fibreboard) conductivity λ, (w/m·k) 0.12 0.12 – density ρ, (kg/m³) 787.22 787.22 – thermal capacity c, (j/kg·k) 1430 1430 – thermal transmittance uwall, w/(m2∙k) 0.57 0.57 0.57 period of temperature oscillation time delay, φ (h) 0,5 14 14 11 1 22 21 20 2 33 31 29 4 48 47 42 5 51 51 46 10 68 68 53 period of temperature oscillation decrement factor, f (–) 0,5 0.037 0.037 0.053 1 0.120 0.120 0.160 2 0.273 0.264 0.356 4 0.483 0.483 0.624 5 0.552 0.552 0.709 10 0.739 0.739 0.894 the massive (mdf – medium density wood fibreboard) materials are characterized by their capability to store energy in their thermal mass and cause a shift delay of temperature waves from outside to inside. this is caused by high thermal conductivity and volumetric thermal capacity of massive (mdf) materials. the due to their low thermal conductivity and volumetric thermal capacity, insulation materials respond like thermal barriers, significantly decreasing temperature fluctuations in the direction of the heat flow path. figure 7 shows the dependence of time delay and figure 8 shows the dependence of wave decrement factor of the enclosures wm-i, wm-ii and wm-iii on different oscillation periods of the outdoor air temperature (fig. 6). when the outdoor air temperature oscillation period is 0.5 h, the inertia of the enclosures wm-i and wm-ii fully suppresses the outdoor air temperature oscillations on the inner surface, in comparison to the homogeneous eps enclosure wm-iii. when the oscillation period of the outdoor air temperature is 1 h, 2 h and 4 h, a 1 min difference in time delay values can be noticed due to different positions of the inertial massive layer in the enclosures. time delay of fluctuations is more significant when the massive layer is oriented to the interior of the model wm-i. when the oscillation period of the outdoor air temperature is 5 h and 10 h, time delay values of the enclosures wm-i and wmii become equal. during oscillation periods, the position of the inertial massive layer in the enclosure does not affect time delay. figure 8 shows decrement factor values of the enclosures wm-i, wm-ii and wm-iii. the closer are the decrement factor values to zero, the more inertial is the material. comparing the values of wave decrement factor through each of three multi-layered enclosures, the inside surface temperature changes faster in model wm-iii than in other models. 47 a) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 0.5 [h] t em pe ra tu re , [ °c ] θe θi b) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 1 [h] t em pe ra tu re ,[° c ] θe θi c) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 2 [h] t em pe ra tu re , [ °c ] θe θi d) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 4 [h] t em pe ra tu re , [ °c ] θe θi ] e) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 501 1001 1501 period of temperature oscillation, 5 [h] t em pe ra tu re , [ °c ] θe θi f) -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 1 1001 period of temperature oscillation, 10 [h] t em pe ra tu re , [ °c ] θe θi fig. 6. the impact of outdoor temperature oscillation to indoor temperature. solid curve shows the exterior air θe and the dotted curve shows the prognosticated internal air temperature θi. outdoor temperature curves are used for walls wm-i, wm-ii, wm-iii simulation. periods of outdoor temperature oscillation varies from 0.5 to 10 hours. (figures from (a) to (f)) 51 68 51 48 33 22 14 68 47 31 21 14 53 46 42 29 20 11 0 10 20 30 40 50 60 70 80 0,5 1 2 4 5 10 period of temperature oscillations, [h] t im e de la y, [m in ] i eps/mdf ii mdf/eps iii eps fig. 7. the time delay dependant on period of outdoor temperature oscillation 0.12 0.273 0.037 0.483 0.739 0.552 0.739 0.552 0.483 0.264 0.12 0.037 0.053 0.16 0.356 0.624 0.709 0.894 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0,5 1 2 4 5 10 period of temperature oscillations, [h] a i/a e i eps/mdf ii mdf/eps iii eps fig. 8. the decrement factor dependant on period of outdoor temperature oscillation 48 7. conclusions 1. continuous outdoor air temperature fluctuations through multi-layered building enclosures were suppressed by high thermal capacitance layers of the enclosure, irrespective of their position. high thermal capacitance layers of enclosures oriented to the interior of the premises suppressed the fluctuations more effectively than the layers oriented to the exterior. 2. when classifying buildings according to their thermal inertia, thermal time constant should be calculated taking into account thermal capacitance of all the layers of building enclosures. 3. the least distorted calculation results were obtained when the multi-layered enclosure was divided into conditional layers so that their number values of the fourier number were close to equal. references antonopoulos k. e. and tzivanidis c. 1995. time constant of greek buildings. energy.greece. 1995. vol. 20(8), 785–802. berg-hallberg e. 1985. realistic design outdoor temperatures. building research and information, 1985, vol. 13(5), 310–317. bruzgevičius p., burlingis a., stankevičius v. 2012. the construction of lithuanian hourly meteorological data for building energy simulation. in procceedings of the 9th international conference of young scientists on energy issues, kaunas, 2012. cibse guide. volume a. design data. 1988. london: the chartered institution of building services engineers. hagentoft c. e. 2001. introduction to building physics. lund, 125–135. hensen l. m., nakhi e. a. 1994. fourier and biot numbers and the accuracy of conduction modelling proceedings of the conference on building environmental performance: facing the future, university of york, 1994, 247–256. incropera f. p., dewitt d. p. 2007. fundamentals of heat and mass transfer 5th ed. new york, 2007, 302–316. iso 8301:1991. thermal insulation. determination of steady-state thermal resistance and related properties. heat flow meter apparatus. 1991. 40 p. karbauskaitė j., stankevičius v., burlingis a., morkvėnas r. 2008. the assessment of freezing risk in apartment buildings after the supply break proceedings of the 8th symposium on building physics in the nordic countries 2008, copenhagen, denmark. 2008, 1341–1347. kontoleon k. j., bikas, d. k. 2005. thermal mass vs. thermal response factors: determining optimal geometrical properties and envelope assemblies of building materials. in international conference passive and low energy cooling for the built environment, santorini, greece. 2005, 345–350. kalema t., pylsy p., hagengran p., jóhannesson g., airaksinen m., dokka t. h., öberg m., pöysti m., rapp k., keski-opas j. 2006. report 184. nordic thermal mass – effect on energy and indoor climate. institute of energy and process engineering. lst en iso 13790: 2008. energy performance of buildings calculation of energy use for space heating and cooling (iso 13790 : 2008). brussels, 2008. 165 p. lst en iso 7730:2005. ergonomics of the thermal environment analytical determination and interpretation of thermal comfort using calculation of the pmv and ppd indices and local thermal comfort criteria (iso 7730:2005). brussels, 2006. 54 p. lst en 12667:2002. thermal performance of building materials and products. determination of thermal resistance by means of guarded hot plate and heat flow meter methods. products of high and medium thermal resistance. brussels, 2002. 53 p. lst en 1602:1998 thermal insulating products for building applications determination of the apparent density. brussels, 1998. 5 p. lst en 1602:1998/ac:2003 thermal insulating products for building applications determination of the apparent density. brussels, 2003. 2 p. lst en 673:2011 glass in building – determinition of thermal transmittance (u value) – calculation method. brussels, 2011. 18 p. pupeikis d., burlingis a., stankevičius v. 2010. the effect of the fourier number on calculation of an unsteady heat transfer of building walls journal of civil engineering and management 16(2), 298–305. pupeikis d., šeduikytė l., bruzgevičius p. 2012. the impact of the fourier number on calculation accuracy of transient heat transfer in homogeneous enclosures. materials science, kaunas, 18(3), 280–283. phokin k. ph. 2006. physics of building‘s envelope. 5th edition. авок-press, моscow. 256. rimkus e., kažys, j., junevičiūtė j., stonevičius e. 2007. lietuvos klimato pokyčių xxi a. prognozė [the prognostication of lithuanian climate changes in the xxi]. geografija, vilnius, 43(2), 37–47. stankevičius v., barkauskas v. 2000. pastatų atitvarų šiluminė fizika [building physics]. technologija, kaunas, 93– 96. str 2.09.02:2005 heating, refrigerating and air-conditioning engineering. šeduikytė l., paukštys v. 2008. evaluation of indoor environment conditions in offices located in buildings with large glazed areas. journal of civil engineering and management. vilnius, 14(1) 39-44. http://dx.doi.org/10.3846/1392-3730.2008.14.39-44 stankevičius v., kairys l. 2005. the effect of stochastically dependent physical parameters on the material’s thermal receptivity coefficient, materials science. kaunas, 11(2), 188–192. received 2013 02 20 accepted after revision 2013 03 05 49 patrikas bruzgevičius. phd student of civil engineering, researcher at the laboratory of thermal building physics of the institute of architecture and construction, ktu. research interests: unsteady heat transfer, thermal processes in buildings. adress: tunelio st. 60, lt-44405, kaunas, lithuania. tel.: +370 37 350779 e-mail: patrikas.bruzgevicius@yahoo.com., patrikas.bruzgevicius@stud.ktu.lt arūnas burlingis. doctor, senior researcher at the laboratory of thermal building physics at the institute of architecture and construction, ktu. research interests: thermal processes in building, thermal and hydro properties of building materials and elements. adress: tunelio st. 60, lt-44405, kaunas, lithuania. tel.: +370 37 350779 e-mail: arunas.burlingis@asi.lt vytautas stankevi ius. doctor habil., full professor, chief researcher at the laboratory of thermal building physics of the institute of architecture and construction, ktu. research interests: heat transfer, technical properties of thermal insulations products. adress: tunelio st. 60, lt-44405, kaunas, lithuania. tel.: +370 37 350779 e-mail: v.stankevicius@ktu.lt darius pupeikis. doctor, lecturer at the department of building materials of the faculty of civil engineering and architecture, ktu. research interests: unsteady heat transfer, thermal energy balance of buildings. adress: studentų st. 48, lt-51367 kaunas, lithuania. tel.: +370 689 77371 e-mail: darius.pupeikis@ktu.lt karolis banionis. doctor, researcher at the laboratory of thermal building physics of the institute of architecture and construction, ktu. research interests: energy efficiency and air permeability of buildings, heat transfer and thermal insulation, thermal impacts of solar radiation. adress: tunelio st. 60, lt-44405, kaunas, lithuania. tel.: +370 37 350779 e-mail: karolis.banionis@ktu.lt rosita norvaišienė. doctor, researcher at the laboratory of thermal building physics of the institute of architecture and construction, ktu. research interests: sustainable building materials; durability testing of building materials; damage due to moisture penetration. adress: tunelio st. 60, lt-44405, kaunas, lithuania. tel.: +370 37 350779 e-mail: rosita.norvaisiene@ktu.lt č 66 darnioji architektūra ir statyba 2014. no. 1(6) journal of sustainable architecture and civil engineering issn 2029–9990 classification and valuation of municipal real estate for execution of municipal functions eglė klumbytė*, raimondas bliūdžius kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu str. 48, lt-51367, kaunas. *corresponding author: egleklumbyte@gmail.com http://dx.doi.org/10.5755/j01.sace.6.1.6199 the quality of satisfying the social and economic needs of residents by the municipality depends on the effective use of municipal real estate, its abundance and quality. the municipal property makes up the basis for their economic activities. to fulfil one of the main municipal goals, i.e. to promote and develop local government, a great deal of attention must be directed to the improvement of municipal real estate management, as well as the optimization and increase of management efficiency of real estate necessary for fulfilling municipal functions. since municipalities own a great deal of real estate unsuitable for carrying out their functions, the paper presents a methodology for reducing the amount of real estate objects redundant for municipal functions. to achieve this, a distinction between functional-objective real estate for fulfilling municipal functions, and real estate that no longer has such a purpose has been made. keywords: municipal real estate, real estate classification, real estate valuation, current value index. 1. introduction in many countries municipalities are not only the owners, but also managers of real estate (re). they control a large amount of real estate, including public buildings, infrastructure objects, schools, health care institutions, social housing and the surrounding land. they also own estate necessary for carrying out their administrative functions. it requires maintenance, foreseeing long-term objectives for its use and investment perspectives. despite the fact that municipalities perform their functions daily, the most suitable real estate management portfolio is necessary for satisfying the public interests best (kaganova et al., 2000). after regaining the independence, lithuania and its municipalities took over not only a considerable amount of real estate, but also many shortfalls in its management. the lack of knowledge, experience and strategic approach has so far been the characteristic trait of real estate management in the public sector. municipal or state institutions are often assigned functions on the basis of the owned real estate, although this should be the opposite case: the need for real estate should be determined by the functions of the state. this may be the reason why currently none of the lithuanian municipalities has a real estate management strategy defining long-term plans for managing the owned property. the majority of lithuanian municipalities had only approved real estate management procedures (zukauskas, 2011). presently, only about 30 % of major european cities are able to provide data on the amount and value of their public real estate (deloitte real estate advisory, 2011); however, the situation is expected to change soon. real estate managers are beginning to acknowledge the benefits of professional real estate management as it would enable not only reducing the costs, but also aid in solving social and developmental issues as well as those concerning expansion of the cities. to reach this purpose collection of information is of primary importance (halfawy, 2008). one of the most relevant objectives to ensure more effective real estate management in the municipalities is to improve the quality of provided services. the reduction of costs for state and municipal real estate management would save the taxpayers’ money. this may be done by applying modern principles of real estate management for administrating the property of the state, i.e. for its purchase, lease, maintenance and renovation. according to the law on self-government of the republic of lithuania (valstybės žinios, 2008, no. 1134290), “municipal functions are the administrative and public service provision functions determined by the constitution, ascribed by the local government, the given and other laws.” in regard to real estate, the municipal function of providing public services is the key, because by doing so, municipalities exploit the owned real estate objects. when 67 providing services, municipalities face problems in the strategic management of real estate portfolio, investment into real estate, its maintenance, financial risk, redundant sales, construction or purchase of necessary buildings, and lack of strategic plans. for these reasons, it is advisable to classify the public services provided by municipalities by ascribing a real estate portfolio necessary for the provision of each public service. currently a unified or official classification of public services does not exist. as proposed by l. lazdynas (2005), public services are divided into several groups according to the possibility to transfer the provision of the services to the private sector. the first group encompasses the municipal services that can neither be privatised nor transferred to the private sector (territorial planning, public infrastructure development, civil safety, traffic control, etc.). the second group includes municipal economic activities which are monopolistic by their nature or cannot be governed by market methods (public transport organization, water supply, etc.). furthermore, the third group encompasses the activities that can be performed by the private sector (collection and management of municipal waste, transportation of passengers and freight, tourism organization, etc.). however, such a classification is rather confusing when it comes to ascribing the necessary real estate objects to separate functions. following the study “analysis of the organization of municipal public service provision” (2010), the services can be classified according to institutional links, functions and services the institutions provide, in which case the function is ascribed to the institution that provides it. one of the examples is the services provided by municipal social support centre. on the other hand, such a classification foregrounds the institution rather than the service. moreover, several institutions may be providing the same services (for instance, a municipality may own several health centres, but they provide the same health care services). another method of classification proposed in the study is based on the customer: the services are then grouped according to their format regardless of several institutions providing them. in such case, a group of services is ascribed a relevant package of real estate. on the basis of the pros and cons of the mentioned classifications, this paper employs the classification of municipal public services in regard to customer. thus, this classification and the structure of municipal real estate proposed by the paper provide for the distinction of real estate portfolio necessary for the provision of certain services (table 1). table 1. public services provided by municipalities and the necessary re services required real estate portfolio health care services non-residential buildings for the execution of municipal administrative functions; health care institutions, hospitals, primary health care centres outpatient facilities. social care services non-residential buildings for the execution of municipal administrative functions; residential buildings. basic/ compulsory education; preschool, afterschool, special education services non-residential buildings for the execution of municipal administrative functions; educational institution buildings; recreation and sports buildings. passenger and load transportation services non-residential buildings for the execution of municipal administrative functions; logistics centres, roads, streets, railways, airports, sea ports, runways. public transport services non-residential buildings for the execution of municipal administrative functions; roads, streets, underpasses, transport stops, traffic control equipment. central heating, water, electricity supply, household sewage collection and cleaning services non-residential buildings for the execution of municipal administrative functions; water-supply, sewage, electricity, heat engineering networks. public waste collection services non-residential buildings for the execution of municipal administrative functions; dumping ground. non-commercial, leisure services non-residential buildings for the execution of municipal administrative functions; public buildings, cultural/ artistic buildings; playing-fields; stadiums; museums; libraries; buildings for public entertainment events; public gardens, zoos, parks, botanical gardens; castles; manors, churches, leisure parks. tourism services non-residential buildings for the execution of municipal administrative functions; recreational buildings; relaxation buildings. cemeteries and cultural heritage, monuments non-residential buildings for the execution of municipal administrative functions; cemetery land, monuments, graveyards, regional, local buildings, building complexes. other free economic zones, industrial parks, land for building/house construction, agricultural land (arable, grazing, and gardens), forest land. 2. methods to diminish the number of municipal real estate objects the following tasks were accomplished: public services provided by municipalities and the necessary re were classified, re object valuation procedure was presented, the factors influencing the demand, supply and market value of re were determined, the factors affecting the value of municipal 68 re were distinguished, municipal re was classified according to the purpose of its management, a methodology for the estimation of re current value index was proposed, and the principal re valuation methods were established. after analysing mentioned tasks, strategic changes in municipal re are planned by dividing re into three principal groups; in the first group, re in use, it is essential to include the costs of property exploitation, maintenance, renewal and repair. similarly, in case of real estate in the second group, new re, the costs necessary for re construction, reconstruction, acquisition under agreements, gift, and use of re taken-over from the state have to be assessed. real estate out of use, ascribed to the third group, is property to be sold, leased, transferred, privatised, or its purpose is changed for the execution of different activities. table 2. strategic changes in municipal real estate after valuation re in use new re re out of use exploitation and maintenance construction sale renewal purchase lease repair taken-over from the state transfer support received as a gift privatization acquired under agreements refusal lease change of purpose reconstruction 3. results real estate valuation is a long and complex process of determining monetary equivalent of real estate object value. this requires the assessor to have especially high qualification and deep knowledge in the valuation methods and instruments, as well as the condition of real estate (especially the segment in question), etc. therefore, fig. 1 provides the general scheme of real estate (re) object valuation process. definition of value assessment 1. address of re object 2. current use of re object 3. assessment of rights and limited conditions 4. setting of value and date of valuation collection and analysis of information 1. about the object history location description 2. general environmental-climatic social and ecological economic-political analysis of the most efficient use of re object 1. physical suitability 2. legal validity 3. financial possibilities 4. maximum of market value income application of value method 1. comparative 2. income 3. expenditure conformity of various assessment results and production of the report on the estimated value fig 1. re object valuation procedure the value of re depends on many factors (fig 2): demand, supply and market value of municipal re physical land, climate, resources, soil, roads, municipal objects, buildings, structures, general outlook, attractiveness, etc. economic economic situation in the country, region, and local level, tendencies in income change, credit policy, interest rate, construction costs, electrical energy rates, transport services, public utilities. social tendencies in population change, ageing and rejuvenation, lifestyle and living standard, family size, level of education, level of criminality administrative limited and liberal zoning, standards and regulations of construction, taxation and financial policy, services of municipal offices: roads, engineering equipment, public transport, fire protection, environmental protection, etc. fig 2. factors influencing the demand, supply and market value of re an important source of influence to the market value assessment is the period when the value is being assessed. short-term market value is in part influenced by the demand, because supply fails to keep up with the changes in the former. on the contrary, in the long-term, the impact of supply becomes higher and thus stronger on the market value. the change in the value of a re object depends on a number of factors that emerge in different stages of the valuation process. the factors influencing re value may be attributed to three different hierarchical levels (table 3). level 1 signifies the influence resulting from the interrelation of four main factors (social, economic, financial and political). this level analyses and assesses the factors of general nature, non-related to any specific re object and independent of it. however, they indirectly influence the re processes in the market and at the same time the re object under valuation. level 2 denotes the influence of local factors, in larger part on the city or city district level. it analyses such factors as the location of the object, its physical properties, sales conditions, time factors and financing conditions. these factors are in immediate relation to the object under valuation as well as the analysis of analogous re objects and contracts. level 3 encompasses the factors related to a re object and, in larger part, conditioned by its properties. it includes the valuation of architectural-constructional and financialrunning factors. the influence of the factors may emerge in different levels at the same time, and this influence is assessed consistently, depending on the explicitness of the valuation and the type of value under assessment. 69 table 3. factors influencing municipal re value influencing factors factors under assessment level 1 (country) economic taxes for re; provision of public objects for residents; financing of construction; living standards of residents condition and prospects of construction and reconstruction; supply; demand; re market social leisure; structure of residents; level of education and culture; needs dominant family size; housing density; re market physical ecology; natural resources; geographical resources technological solutions in land exploitation, geodesy and topography political laws on mortgage; laws on construction; laws on taxes; laws on property; laws on re operations; laws on ecology territory zoning; legal regulations on mortgage; law on credit policy; cadastre; law on re valuation; political stability level 2 (city, municipality) location transport accessibility; existence of social-cultural objects; pedestrian accessibility arrangement of objects in the town (municipal) plan; condition of communication networks; adjacent environment physical properties physical parameters; functional suitability and use re condition; attractiveness; comfort; construction and exploitation quality sale conditions mortgages and surety; special contract conditions motives of salespeople and purchasers time factors date of valuation dates of analogous contracts on re objects financial conditions credit due dates conditions for allocation of finance level 3 (building) architectural-constructional volume-layout indicators financial-running income running expenditure; value of construction as re and its environment are in mutual effect, the surrounding factors and those related to the re and influencing its value are determined during the process of valuation. thus, four main factors defining the demand for residential re may be distinguished as follows: ▪ customers’ needs; ▪ residents’ income; ▪ prices of residential housing; ▪ number of households in the residential re market the assessment of market value requires taking into account that it is also influenced by the period when the value is being assessed. in the short-term, the market value is affected by the demand because the supply fails to keep up with the changes in the former. on the contrary, in the long-term, the impact of supply becomes higher and thus stronger on the market value. in order to reduce the amount of re objects that are not suitable for fulfilling municipal functions it is vital to distinguish functional-objective re, i.e. re objects used for fulfilling municipal functions and re that no longer has such a function (commercial property). the given classification enables a differentiated selection of methods for the management and disposition of municipal re. a relevant task in this conception is to increase the income for re that is set for privatization and no longer used to fulfil municipal functions. the given classification enables a differentiated selection of methods for the management and disposition of municipal re. municipal re functional-objective commercial administrative purpose for unitary enterprises objective means, normative method privatization transfer of management lease maximization of object value, in case of conformity to functional standard maximization of result (profit) in case of well-justified management expenses means and methods of management management efficiency criteria fig 3. classification of municipal re according to the purpose of management the given classification enables a differentiated selection of methods for the management and disposition of municipal re. a relevant task in this conception is to increase the income for re that is set for privatization and no longer used to fulfil municipal functions. strategic objectives of municipal re privatization, lease and transfer of management under the right of trust are similar in their nature, i.e. maximum income. therefore, to establish a reasonable ratio between the re objects for privatization generating one-off income, and those used to generate steady income (lease, management under the right of trust), the authors propose applying the municipal re current value ratio (1): exploitation quality sale conditions mortgages and surety; special contract conditions motives of salespeople and purchasers time factors date of valuation dates of analogous contracts on re objects financial conditions credit due dates conditions for allocation of finance level 3 (building) architectural-constructional volume-layout indicators financial-running income running expenditure; value of construction the change in the value of a re object depends on a number of factors that emerge in different stages of the valuation process. the factors influencing re value may be attributed to three different hierarchical levels (table 3). level 1 signifies the influence resulting from the interrelation of four main factors (social, economic, financial and political). this level analyses and assesses the factors of general nature, non-related to any specific re object and independent of it. however, they indirectly influence the re processes in the market and at the same time the re object under valuation. level 2 denotes the influence of local factors, in larger part on the city or city district level. it analyses such factors as the location of the object, its physical properties, sales conditions, time factors and financing conditions. these factors are in immediate relation to the object under valuation as well as the analysis of analogous re objects and contracts. level 3 encompasses the factors related to a re object and, in larger part, conditioned by its properties. it includes the valuation of architectural-constructional and financialrunning factors. the influence of the factors may emerge in different levels at the same time, and this influence is assessed consistently, depending on the explicitness of the valuation and the type of value under assessment. as re and its environment are in mutual effect, the surrounding factors and those related to the re and influencing its value are determined during the process of valuation. thus, four main factors defining the demand for residential re may be distinguished as follows: • customers’ needs; • residents’ income; • prices of residential housing; • number of households in the residential re market the assessment of market value requires taking into account that it is also influenced by the period when the value is being assessed. in the short-term, the market value is affected by the demand because the supply fails to keep up with the changes in the former. on the contrary, in the long-term, the impact of supply becomes higher and thus stronger on the market value. in order to reduce the amount of re objects that are not suitable for fulfilling municipal functions it is vital to distinguish functional-objective re, i.e. re objects used for fulfilling municipal functions and re that no longer has such a function (commercial property). the given classification enables a differentiated selection of methods for the management and disposition of municipal re. a relevant task in this conception is to increase the income for re that is set for privatization and no longer used to fulfil municipal functions. the given classification enables a differentiated selection of methods for the management and disposition of municipal re. municipal re functional-objective commercial administ rative purpose for unitary enterprises means and methods of management objectiv e means, normative method privatization transfer of manageme nt lease management efficiency criteria maximization of object value, in case of conformity to functional standard maximization of result (profit) in case of welljustified management expenses fig 3. classification of municipal re according to the purpose of management the given classification enables a differentiated selection of methods for the management and disposition of municipal re. a relevant task in this conception is to increase the income for re that is set for privatization and no longer used to fulfil municipal functions. strategic objectives of municipal re privatization, lease and transfer of management under the right of trust are similar in their nature, i.e. maximum income. therefore, to establish a reasonable ratio between the re objects for privatization generating one-off income, and those used to generate steady income (lease, management under the right of trust), the authors propose applying the municipal re current value ratio (1): max )1( 11 11 ⇒+ + += ∑∑∑∑ == == m k p j n t t t n a r s e se p i p vv (1) here: v e – current (present) value of municipal re; s – serial number of municipal re object for fulfilling a particular municipal function; r – number of municipal re objects for fulfilling municipal functions; v e ‒ current value of re object for fulfilling a particular municipal function; p a – income from the n th municipal re object transferred for lease or management under the right of trust; j – number of municipal re objects transferred for lease or management under the right of trust; , (1) where: ve – current (present) value of municipal re; s – serial number of municipal re object for fulfilling a particular municipal function; r – number of municipal re objects for fulfilling municipal functions; v e – current value of re object for fulfilling a particular municipal function; pa – income from the nth municipal re object transferred for 70 lease or management under the right of trust; j – number of municipal re objects transferred for lease or management under the right of trust; t – number of lease periods when re object is used under a lease of trust contract; t – serial number of a lease period; in – bank rate signifying the average profitability of the nth municipal re object transferred for lease or management under the right of trust; pp – one-off income from the privatization (sale) of the kth municipal re object; k – serial number of municipal re object for sale (privatization); m – number of municipal re objects for sale (privatization); it is worthwhile noting that this equation reaches the maximum value only when the following condition is fulfilled (2): t – number of lease periods when re object is used under a lease of trust contract t – serial number of a lease period; i n – bank rate signifying the average profitability of the n th municipal re object transferred for lease or management under the right of trust; p p – one-off income from the privatization (sale) of the k th municipal re object; k – serial number of municipal re object for sale (privatization); m – number of municipal re objects for sale (privatization); it is worthwhile noting that this equation reaches the maximum value only when the following condition is fulfilled (2): ∑ = + > t t t n ae n i p v 1 )1( (2) here: e n v – current value of the n th municipal re object transferred for lease or management under the right of trust; this suggests that the value of a municipal re object is the greatest (and also its management is effective) if the sale (privatization) of the object in the current period generates more income than during the whole period of its lease or management under the right of trust. however, this requires taking into account that municipal re also has to be optimised. to be more precise, any re objects for carrying out particular municipal functions, but not used for that purpose, should be transferred to the commercial municipal re group. when the value of municipal re for fulfilling municipal functions diminishes, the value of commercial municipal re increases. in this way, the goal of municipal re management optimization evolves to the task of increasing the municipal re management effectiveness, which, in its turn, aids in improving the effectiveness of municipal budget use. in such case, the valuation of the whole municipal re, including both the objects for fulfilling municipal functions and those of commercial purpose, becomes a relevant task. the complex of municipal re is the total of all re objects owned by a municipality; it encompasses such objects as land, re allocated to municipal enterprises, separate buildings, structures and premises. the authors claim that the complex of municipal re is a specific, territorial-economic asset that, differently from natural resources, can assure rapid economic development of a municipality if used effectively. the complexity and versatility of problems in the management of such an economically and socially relevant resource as municipal re requires analysing it as a strategic resource, the effective management of which may only be assured by the use of strategic planning and management mechanisms. a long-term municipal development programme must be based on the development of its resources potential, primarily focusing on immovable resources, i.e. re. the management of re, as a resource, provides for the development of its motion plan and its annual approval. the plan should include re acquisition, use and transfer (assignation) plans, as well as be supplemented with forecasts for at least two upcoming years and agreed with the order of current municipal budget and investment planning. in lithuania the value of re is determined by applying the methods established by the international accounting standards committee and approved by the decision no. 1049 (zin., 2005, nr. 76-2741) government of the republic of lithuania on 29 september 2009. thus, the methods include the following: • comparative value (sale price of analogues); • regenerative value (expenses); • income value (income capitalization or cash flow discount); • other methods authorised by the government of the republic of lithuania and established by the international practice (mass valuation). in practice there are three traditional re valuation methods: comparative (or market) value, income value and regenerative (expense) value. to establish the market value of re the comparative value method is most often applied (raslanas, s., tupenaitė, l., 2007). the essence of this method is comparison, i.e. the value of re is determined by comparing the prices of actual contracts on analogous objects at the same time taking into account small differences between the valued object and its analogue (gasilionis, a., kasperavicius, r., 2006). a. gasilionis and r. kasperavicius (2006) explain that in the income value method, the value of an asset or business is estimated by capitalising (discounting) net income (cash flows) received from the use of the asset or business. this method is applied when the value of using the asset is expected to objectively show its market value in use. the estimation of regenerative value is based on the concept of re reproduction, i.e. speculating on the sum of money required to fully reproduce the valued object. on such basis the regenerative value is understood as the sum of rebuilding expenses used to create economic well-being as regards the re. the expenses for rebuilding structures and equipment are determined on the day of the valuation, but also following the statistical research carried out in the corresponding year. for this reason, construction price indexes are used to recalculate rebuilding expenses on the day of valuation (šulija, 2009). income value method the value in use of the object is estimated applying the following formula: r vp v = (3) here: v – value in use; vp – annual operating income; r – capitalization rate. operating income is calculated by subtracting operating expenses from gross income. annual gross income includes the money from selling the production obtained from land exploitation (by the owner), or money received by the owner from the lessees of land, structures or other re objects. operating expenses encompass the expenses for the lease, exploitation and administration of re (public utilities and other services) and overheads. in a simplified case, the capitalization rate index may be compared to the interest bond rate or average bank interest rate (i.e. when the purchase of re is viewed as an , (2) where: env – current value of the n th municipal re object transferred for lease or management under the right of trust; this suggests that the value of a municipal re object is the greatest (and also its management is effective) if the sale (privatization) of the object in the current period generates more income than during the whole period of its lease or management under the right of trust. however, this requires taking into account that municipal re also has to be optimised. to be more precise, any re objects for carrying out particular municipal functions, but not used for that purpose, should be transferred to the commercial municipal re group. when the value of municipal re for fulfilling municipal functions diminishes, the value of commercial municipal re increases. in this way, the goal of municipal re management optimization evolves to the task of increasing the municipal re management effectiveness, which, in its turn, aids in improving the effectiveness of municipal budget use. in such case, the valuation of the whole municipal re, including both the objects for fulfilling municipal functions and those of commercial purpose, becomes a relevant task. the complex of municipal re is the total of all re objects owned by a municipality; it encompasses such objects as land, re allocated to municipal enterprises, separate buildings, structures and premises. the authors claim that the complex of municipal re is a specific, territorial-economic asset that, differently from natural resources, can assure rapid economic development of a municipality if used effectively. the complexity and versatility of problems in the management of such an economically and socially relevant resource as municipal re requires analysing it as a strategic resource, the effective management of which may only be assured by the use of strategic planning and management mechanisms. a long-term municipal development programme must be based on the development of its resources potential, primarily focusing on immovable resources, i.e. re. the management of re, as a resource, provides for the development of its motion plan and its annual approval. the plan should include re acquisition, use and transfer (assignation) plans, as well as be supplemented with forecasts for at least two upcoming years and agreed with the order of current municipal budget and investment planning. in lithuania the value of re is determined by applying the methods established by the international accounting standards committee and approved by the decision no. 1049 (zin., 2005, nr. 76-2741) government of the republic of lithuania on 29 september 2009. thus, the methods include the following: ▪ comparative value (sale price of analogues); ▪ regenerative value (expenses); ▪ income value (income capitalization or cash flow discount); ▪ other methods authorised by the government of the republic of lithuania and established by the international practice (mass valuation). in practice there are three traditional re valuation methods: comparative (or market) value, income value and regenerative (expense) value. to establish the market value of re the comparative value method is most often applied (raslanas, s., tupenaitė, l., 2007). the essence of this method is comparison, i.e. the value of re is determined by comparing the prices of actual contracts on analogous objects at the same time taking into account small differences between the valued object and its analogue (gasilionis, a., kasperavicius, r., 2006). a. gasilionis and r. kasperavicius (2006) explain that in the income value method, the value of an asset or business is estimated by capitalising (discounting) net income (cash flows) received from the use of the asset or business. this method is applied when the value of using the asset is expected to objectively show its market value in use. the estimation of regenerative value is based on the concept of re reproduction, i.e. speculating on the sum of money required to fully reproduce the valued object. on such basis the regenerative value is understood as the sum of rebuilding expenses used to create economic well-being as regards the re. the expenses for rebuilding structures and equipment are determined on the day of the valuation, but also following the statistical research carried out in the corresponding year. for this reason, construction price indexes are used to recalculate rebuilding expenses on the day of valuation (šulija, 2009). income value method the value in use of the object is estimated applying the following formula: t – number of lease periods when re object is used under a lease of trust contract t – serial number of a lease period; i n – bank rate signifying the average profitability of the n th municipal re object transferred for lease or management under the right of trust; p p – one-off income from the privatization (sale) of the k th municipal re object; k – serial number of municipal re object for sale (privatization); m – number of municipal re objects for sale (privatization); it is worthwhile noting that this equation reaches the maximum value only when the following condition is fulfilled (2): ∑ = + > t t t n ae n i p v 1 )1( (2) here: e n v – current value of the n th municipal re object transferred for lease or management under the right of trust; this suggests that the value of a municipal re object is the greatest (and also its management is effective) if the sale (privatization) of the object in the current period generates more income than during the whole period of its lease or management under the right of trust. however, this requires taking into account that municipal re also has to be optimised. to be more precise, any re objects for carrying out particular municipal functions, but not used for that purpose, should be transferred to the commercial municipal re group. when the value of municipal re for fulfilling municipal functions diminishes, the value of commercial municipal re increases. in this way, the goal of municipal re management optimization evolves to the task of increasing the municipal re management effectiveness, which, in its turn, aids in improving the effectiveness of municipal budget use. in such case, the valuation of the whole municipal re, including both the objects for fulfilling municipal functions and those of commercial purpose, becomes a relevant task. the complex of municipal re is the total of all re objects owned by a municipality; it encompasses such objects as land, re allocated to municipal enterprises, separate buildings, structures and premises. the authors claim that the complex of municipal re is a specific, territorial-economic asset that, differently from natural resources, can assure rapid economic development of a municipality if used effectively. the complexity and versatility of problems in the management of such an economically and socially relevant resource as municipal re requires analysing it as a strategic resource, the effective management of which may only be assured by the use of strategic planning and management mechanisms. a long-term municipal development programme must be based on the development of its resources potential, primarily focusing on immovable resources, i.e. re. the management of re, as a resource, provides for the development of its motion plan and its annual approval. the plan should include re acquisition, use and transfer (assignation) plans, as well as be supplemented with forecasts for at least two upcoming years and agreed with the order of current municipal budget and investment planning. in lithuania the value of re is determined by applying the methods established by the international accounting standards committee and approved by the decision no. 1049 (zin., 2005, nr. 76-2741) government of the republic of lithuania on 29 september 2009. thus, the methods include the following: • comparative value (sale price of analogues); • regenerative value (expenses); • income value (income capitalization or cash flow discount); • other methods authorised by the government of the republic of lithuania and established by the international practice (mass valuation). in practice there are three traditional re valuation methods: comparative (or market) value, income value and regenerative (expense) value. to establish the market value of re the comparative value method is most often applied (raslanas, s., tupenaitė, l., 2007). the essence of this method is comparison, i.e. the value of re is determined by comparing the prices of actual contracts on analogous objects at the same time taking into account small differences between the valued object and its analogue (gasilionis, a., kasperavicius, r., 2006). a. gasilionis and r. kasperavicius (2006) explain that in the income value method, the value of an asset or business is estimated by capitalising (discounting) net income (cash flows) received from the use of the asset or business. this method is applied when the value of using the asset is expected to objectively show its market value in use. the estimation of regenerative value is based on the concept of re reproduction, i.e. speculating on the sum of money required to fully reproduce the valued object. on such basis the regenerative value is understood as the sum of rebuilding expenses used to create economic well-being as regards the re. the expenses for rebuilding structures and equipment are determined on the day of the valuation, but also following the statistical research carried out in the corresponding year. for this reason, construction price indexes are used to recalculate rebuilding expenses on the day of valuation (šulija, 2009). income value method the value in use of the object is estimated applying the following formula: r vp v = (3) here: v – value in use; vp – annual operating income; r – capitalization rate. operating income is calculated by subtracting operating expenses from gross income. annual gross income includes the money from selling the production obtained from land exploitation (by the owner), or money received by the owner from the lessees of land, structures or other re objects. operating expenses encompass the expenses for the lease, exploitation and administration of re (public utilities and other services) and overheads. in a simplified case, the capitalization rate index may be compared to the interest bond rate or average bank interest rate (i.e. when the purchase of re is viewed as an , (3) where: v – value in use; vp – annual operating income; r – capitalization rate. operating income is calculated by subtracting operating expenses from gross income. annual gross income includes the money from selling the production obtained from land exploitation (by the owner), or money received by the owner from the lessees of land, structures or other re objects. operating expenses encompass the expenses for the lease, exploitation and administration of re (public utilities and other services) and overheads. 71 in a simplified case, the capitalization rate index may be compared to the interest bond rate or average bank interest rate (i.e. when the purchase of re is viewed as an investment expected to generate no less profit than another alternative, in this case bank interest when the money is kept in a bank). however, it can also be estimated by the given formula: investment expected to generate no less profit than another alternative, in this case bank interest when the money is kept in a bank). however, it can also be estimated by the given formula: pv vp r = (4) here: vp – annual operating income from re objects recently sold and similar to the valued one; pv – value of re objects recently sold and similar to the valued one. when cash flow discount method is applied to appraise re generating income, one of the indicators of re value is the current value of future income flow (dv). this means the estimation of the extent to which the profit received in n years will equal to the current value, since having invested an amount of money p, in a year it will equal to the current value that will have increased due to the discount coefficient r d : )1( 1 d rdvp +⋅= (5) thus, after a year the current value will amount to d r p dv + = 1 1 (6) after n years the current value will make up ∑ = + = n i i di i r p dv 1 )1( (7) here: p i – cash flows received in i th year; r i – discount rates of i th year. since in the end of the calculation period of n years, re will still be valuable, it is relevant to estimate the residual value (rv), which can be defined as re value at the end of the calculation period. hence, re income value in use will equal to the sum of discount future income and discount residual value (aleknavičius, 2008). regenerative value method this method consists of two stages of re value estimation: • estimation of expenses for rebuilding the object; • estimation of depreciation value of the object. for this purpose, two following methods may be used: • rebuilding of the object; • replacement of the object with another one. the object under valuation by the regenerative value method is thoroughly analysed and divided into elements, for the development, production, instalment or building (mounting) of which a database of market costs has been established. in other words, it includes scope (measurement) units and establishes the direct costs (materials, workforce, mechanisms, etc.) and overheads (design and management, storage, etc.) for the development, production, instalment or building (mounting) of the units as well as the average profit received by the developer, producer and builder (mounter) of the production. if the purpose of the valuation is to determine the regenerative value, the total depreciation level of a re object is estimated by adding up the depreciation of its separate construction elements and multiplying by the share of an element in the total value of the object: 100 1 ∑ = ⋅ = n i ii f jq q (8) here: q f – total depreciation of a re object (%); q i – actual depreciation of i th element (%); j i – weight of i th element in the total value of the object (%); n – number of construction elements. the only advantage of this method is that it provides rather convincing results. yet, they are always subjective because of the different level of expert qualification. the estimation of depreciation by applying the method requires a great input of time, work and finances, which is why it is rarely used. another shortcoming is that its results quickly go out of date. moreover, such valuation very often skips the functional and external depreciation, which provides very little information to perform an accurate re object valuation. 4. conclusions there is still a lack of structured legislation or scientific research providing an integrated analysis and summary of peculiarities in municipal re classification, appraisal and management. the variety of classification means to classify the property and their incompatibility often cause inaccuracies in the structure and value of municipal re. not enough of attention is given to the estimation of actual value of municipal re. this is often limited to legislation and reports on the owned asset submitted by municipalities. to establish a reasonable ratio between the re objects for privatization generating one-off income, and those used to generate steady income (lease, management under the right of trust), the authors propose applying the municipal re current value ratio. if the buildings were evaluated and grouped under the classification and evaluation methodology provided by the authors and a database of the available municipal re was developed, the municipalities would be aware of the available type and amount of re they own, which would facilitate the estimation of the need for re to perform municipal functions. this classification allows adequate assessment of the existing municipal real estate portfolio and development of new rational alternatives. clearly established strategic real estate portfolio and management changes would ensure the satisfaction of public interests, ensure the appropriate financing sources, and encourage public–private partnerships. , (4) where: vp – annual operating income from re objects recently sold and similar to the valued one; pv – value of re objects recently sold and similar to the valued one. when cash flow discount method is applied to appraise re generating income, one of the indicators of re value is the current value of future income flow (dv). this means the estimation of the extent to which the profit received in n years will equal to the current value, since having invested an amount of money p, in a year it will equal to the current value that will have increased due to the discount coefficient rd: investment expected to generate no less profit than another alternative, in this case bank interest when the money is kept in a bank). however, it can also be estimated by the given formula: pv vp r = (4) here: vp – annual operating income from re objects recently sold and similar to the valued one; pv – value of re objects recently sold and similar to the valued one. when cash flow discount method is applied to appraise re generating income, one of the indicators of re value is the current value of future income flow (dv). this means the estimation of the extent to which the profit received in n years will equal to the current value, since having invested an amount of money p, in a year it will equal to the current value that will have increased due to the discount coefficient r d : )1( 1 d rdvp +⋅= (5) thus, after a year the current value will amount to d r p dv + = 1 1 (6) after n years the current value will make up ∑ = + = n i i di i r p dv 1 )1( (7) here: p i – cash flows received in i th year; r i – discount rates of i th year. since in the end of the calculation period of n years, re will still be valuable, it is relevant to estimate the residual value (rv), which can be defined as re value at the end of the calculation period. hence, re income value in use will equal to the sum of discount future income and discount residual value (aleknavičius, 2008). regenerative value method this method consists of two stages of re value estimation: • estimation of expenses for rebuilding the object; • estimation of depreciation value of the object. for this purpose, two following methods may be used: • rebuilding of the object; • replacement of the object with another one. the object under valuation by the regenerative value method is thoroughly analysed and divided into elements, for the development, production, instalment or building (mounting) of which a database of market costs has been established. in other words, it includes scope (measurement) units and establishes the direct costs (materials, workforce, mechanisms, etc.) and overheads (design and management, storage, etc.) for the development, production, instalment or building (mounting) of the units as well as the average profit received by the developer, producer and builder (mounter) of the production. if the purpose of the valuation is to determine the regenerative value, the total depreciation level of a re object is estimated by adding up the depreciation of its separate construction elements and multiplying by the share of an element in the total value of the object: 100 1 ∑ = ⋅ = n i ii f jq q (8) here: q f – total depreciation of a re object (%); q i – actual depreciation of i th element (%); j i – weight of i th element in the total value of the object (%); n – number of construction elements. the only advantage of this method is that it provides rather convincing results. yet, they are always subjective because of the different level of expert qualification. the estimation of depreciation by applying the method requires a great input of time, work and finances, which is why it is rarely used. another shortcoming is that its results quickly go out of date. moreover, such valuation very often skips the functional and external depreciation, which provides very little information to perform an accurate re object valuation. 4. conclusions there is still a lack of structured legislation or scientific research providing an integrated analysis and summary of peculiarities in municipal re classification, appraisal and management. the variety of classification means to classify the property and their incompatibility often cause inaccuracies in the structure and value of municipal re. not enough of attention is given to the estimation of actual value of municipal re. this is often limited to legislation and reports on the owned asset submitted by municipalities. to establish a reasonable ratio between the re objects for privatization generating one-off income, and those used to generate steady income (lease, management under the right of trust), the authors propose applying the municipal re current value ratio. if the buildings were evaluated and grouped under the classification and evaluation methodology provided by the authors and a database of the available municipal re was developed, the municipalities would be aware of the available type and amount of re they own, which would facilitate the estimation of the need for re to perform municipal functions. this classification allows adequate assessment of the existing municipal real estate portfolio and development of new rational alternatives. clearly established strategic real estate portfolio and management changes would ensure the satisfaction of public interests, ensure the appropriate financing sources, and encourage public–private partnerships. . (5) thus, after a year the current value will amount to investment expected to generate no less profit than another alternative, in this case bank interest when the money is kept in a bank). however, it can also be estimated by the given formula: pv vp r = (4) here: vp – annual operating income from re objects recently sold and similar to the valued one; pv – value of re objects recently sold and similar to the valued one. when cash flow discount method is applied to appraise re generating income, one of the indicators of re value is the current value of future income flow (dv). this means the estimation of the extent to which the profit received in n years will equal to the current value, since having invested an amount of money p, in a year it will equal to the current value that will have increased due to the discount coefficient r d : )1( 1 d rdvp +⋅= (5) thus, after a year the current value will amount to d r p dv + = 1 1 (6) after n years the current value will make up ∑ = + = n i i di i r p dv 1 )1( (7) here: p i – cash flows received in i th year; r i – discount rates of i th year. since in the end of the calculation period of n years, re will still be valuable, it is relevant to estimate the residual value (rv), which can be defined as re value at the end of the calculation period. hence, re income value in use will equal to the sum of discount future income and discount residual value (aleknavičius, 2008). regenerative value method this method consists of two stages of re value estimation: • estimation of expenses for rebuilding the object; • estimation of depreciation value of the object. for this purpose, two following methods may be used: • rebuilding of the object; • replacement of the object with another one. the object under valuation by the regenerative value method is thoroughly analysed and divided into elements, for the development, production, instalment or building (mounting) of which a database of market costs has been established. in other words, it includes scope (measurement) units and establishes the direct costs (materials, workforce, mechanisms, etc.) and overheads (design and management, storage, etc.) for the development, production, instalment or building (mounting) of the units as well as the average profit received by the developer, producer and builder (mounter) of the production. if the purpose of the valuation is to determine the regenerative value, the total depreciation level of a re object is estimated by adding up the depreciation of its separate construction elements and multiplying by the share of an element in the total value of the object: 100 1 ∑ = ⋅ = n i ii f jq q (8) here: q f – total depreciation of a re object (%); q i – actual depreciation of i th element (%); j i – weight of i th element in the total value of the object (%); n – number of construction elements. the only advantage of this method is that it provides rather convincing results. yet, they are always subjective because of the different level of expert qualification. the estimation of depreciation by applying the method requires a great input of time, work and finances, which is why it is rarely used. another shortcoming is that its results quickly go out of date. moreover, such valuation very often skips the functional and external depreciation, which provides very little information to perform an accurate re object valuation. 4. conclusions there is still a lack of structured legislation or scientific research providing an integrated analysis and summary of peculiarities in municipal re classification, appraisal and management. the variety of classification means to classify the property and their incompatibility often cause inaccuracies in the structure and value of municipal re. not enough of attention is given to the estimation of actual value of municipal re. this is often limited to legislation and reports on the owned asset submitted by municipalities. to establish a reasonable ratio between the re objects for privatization generating one-off income, and those used to generate steady income (lease, management under the right of trust), the authors propose applying the municipal re current value ratio. if the buildings were evaluated and grouped under the classification and evaluation methodology provided by the authors and a database of the available municipal re was developed, the municipalities would be aware of the available type and amount of re they own, which would facilitate the estimation of the need for re to perform municipal functions. this classification allows adequate assessment of the existing municipal real estate portfolio and development of new rational alternatives. clearly established strategic real estate portfolio and management changes would ensure the satisfaction of public interests, ensure the appropriate financing sources, and encourage public–private partnerships. . (6) after n years the current value will make up investment expected to generate no less profit than another alternative, in this case bank interest when the money is kept in a bank). however, it can also be estimated by the given formula: pv vp r = (4) here: vp – annual operating income from re objects recently sold and similar to the valued one; pv – value of re objects recently sold and similar to the valued one. when cash flow discount method is applied to appraise re generating income, one of the indicators of re value is the current value of future income flow (dv). this means the estimation of the extent to which the profit received in n years will equal to the current value, since having invested an amount of money p, in a year it will equal to the current value that will have increased due to the discount coefficient r d : )1( 1 d rdvp +⋅= (5) thus, after a year the current value will amount to d r p dv + = 1 1 (6) after n years the current value will make up ∑ = + = n i i di i r p dv 1 )1( (7) here: p i – cash flows received in i th year; r i – discount rates of i th year. since in the end of the calculation period of n years, re will still be valuable, it is relevant to estimate the residual value (rv), which can be defined as re value at the end of the calculation period. hence, re income value in use will equal to the sum of discount future income and discount residual value (aleknavičius, 2008). regenerative value method this method consists of two stages of re value estimation: • estimation of expenses for rebuilding the object; • estimation of depreciation value of the object. for this purpose, two following methods may be used: • rebuilding of the object; • replacement of the object with another one. the object under valuation by the regenerative value method is thoroughly analysed and divided into elements, for the development, production, instalment or building (mounting) of which a database of market costs has been established. in other words, it includes scope (measurement) units and establishes the direct costs (materials, workforce, mechanisms, etc.) and overheads (design and management, storage, etc.) for the development, production, instalment or building (mounting) of the units as well as the average profit received by the developer, producer and builder (mounter) of the production. if the purpose of the valuation is to determine the regenerative value, the total depreciation level of a re object is estimated by adding up the depreciation of its separate construction elements and multiplying by the share of an element in the total value of the object: 100 1 ∑ = ⋅ = n i ii f jq q (8) here: q f – total depreciation of a re object (%); q i – actual depreciation of i th element (%); j i – weight of i th element in the total value of the object (%); n – number of construction elements. the only advantage of this method is that it provides rather convincing results. yet, they are always subjective because of the different level of expert qualification. the estimation of depreciation by applying the method requires a great input of time, work and finances, which is why it is rarely used. another shortcoming is that its results quickly go out of date. moreover, such valuation very often skips the functional and external depreciation, which provides very little information to perform an accurate re object valuation. 4. conclusions there is still a lack of structured legislation or scientific research providing an integrated analysis and summary of peculiarities in municipal re classification, appraisal and management. the variety of classification means to classify the property and their incompatibility often cause inaccuracies in the structure and value of municipal re. not enough of attention is given to the estimation of actual value of municipal re. this is often limited to legislation and reports on the owned asset submitted by municipalities. to establish a reasonable ratio between the re objects for privatization generating one-off income, and those used to generate steady income (lease, management under the right of trust), the authors propose applying the municipal re current value ratio. if the buildings were evaluated and grouped under the classification and evaluation methodology provided by the authors and a database of the available municipal re was developed, the municipalities would be aware of the available type and amount of re they own, which would facilitate the estimation of the need for re to perform municipal functions. this classification allows adequate assessment of the existing municipal real estate portfolio and development of new rational alternatives. clearly established strategic real estate portfolio and management changes would ensure the satisfaction of public interests, ensure the appropriate financing sources, and encourage public–private partnerships. , (7) where: pi – cash flows received in ith year; ri – discount rates of ith year. since in the end of the calculation period of n years, re will still be valuable, it is relevant to estimate the residual value (rv), which can be defined as re value at the end of the calculation period. hence, re income value in use will equal to the sum of discount future income and discount residual value (aleknavičius, 2008). regenerative value method this method consists of two stages of re value estimation: ▪ estimation of expenses for rebuilding the object; ▪ estimation of depreciation value of the object. for this purpose, two following methods may be used: ▪ rebuilding of the object; ▪ replacement of the object with another one. the object under valuation by the regenerative value method is thoroughly analysed and divided into elements, for the development, production, instalment or building (mounting) of which a database of market costs has been established. in other words, it includes scope (measurement) units and establishes the direct costs (materials, workforce, mechanisms, etc.) and overheads (design and management, storage, etc.) for the development, production, instalment or building (mounting) of the units as well as the average profit received by the developer, producer and builder (mounter) of the production. if the purpose of the valuation is to determine the regenerative value, the total depreciation level of a re object is estimated by adding up the depreciation of its separate construction elements and multiplying by the share of an element in the total value of the object: investment expected to generate no less profit than another alternative, in this case bank interest when the money is kept in a bank). however, it can also be estimated by the given formula: pv vp r = (4) here: vp – annual operating income from re objects recently sold and similar to the valued one; pv – value of re objects recently sold and similar to the valued one. when cash flow discount method is applied to appraise re generating income, one of the indicators of re value is the current value of future income flow (dv). this means the estimation of the extent to which the profit received in n years will equal to the current value, since having invested an amount of money p, in a year it will equal to the current value that will have increased due to the discount coefficient r d : )1( 1 d rdvp +⋅= (5) thus, after a year the current value will amount to d r p dv + = 1 1 (6) after n years the current value will make up ∑ = + = n i i di i r p dv 1 )1( (7) here: p i – cash flows received in i th year; r i – discount rates of i th year. since in the end of the calculation period of n years, re will still be valuable, it is relevant to estimate the residual value (rv), which can be defined as re value at the end of the calculation period. hence, re income value in use will equal to the sum of discount future income and discount residual value (aleknavičius, 2008). regenerative value method this method consists of two stages of re value estimation: • estimation of expenses for rebuilding the object; • estimation of depreciation value of the object. for this purpose, two following methods may be used: • rebuilding of the object; • replacement of the object with another one. the object under valuation by the regenerative value method is thoroughly analysed and divided into elements, for the development, production, instalment or building (mounting) of which a database of market costs has been established. in other words, it includes scope (measurement) units and establishes the direct costs (materials, workforce, mechanisms, etc.) and overheads (design and management, storage, etc.) for the development, production, instalment or building (mounting) of the units as well as the average profit received by the developer, producer and builder (mounter) of the production. if the purpose of the valuation is to determine the regenerative value, the total depreciation level of a re object is estimated by adding up the depreciation of its separate construction elements and multiplying by the share of an element in the total value of the object: 100 1 ∑ = ⋅ = n i ii f jq q (8) here: q f – total depreciation of a re object (%); q i – actual depreciation of i th element (%); j i – weight of i th element in the total value of the object (%); n – number of construction elements. the only advantage of this method is that it provides rather convincing results. yet, they are always subjective because of the different level of expert qualification. the estimation of depreciation by applying the method requires a great input of time, work and finances, which is why it is rarely used. another shortcoming is that its results quickly go out of date. moreover, such valuation very often skips the functional and external depreciation, which provides very little information to perform an accurate re object valuation. 4. conclusions there is still a lack of structured legislation or scientific research providing an integrated analysis and summary of peculiarities in municipal re classification, appraisal and management. the variety of classification means to classify the property and their incompatibility often cause inaccuracies in the structure and value of municipal re. not enough of attention is given to the estimation of actual value of municipal re. this is often limited to legislation and reports on the owned asset submitted by municipalities. to establish a reasonable ratio between the re objects for privatization generating one-off income, and those used to generate steady income (lease, management under the right of trust), the authors propose applying the municipal re current value ratio. if the buildings were evaluated and grouped under the classification and evaluation methodology provided by the authors and a database of the available municipal re was developed, the municipalities would be aware of the available type and amount of re they own, which would facilitate the estimation of the need for re to perform municipal functions. this classification allows adequate assessment of the existing municipal real estate portfolio and development of new rational alternatives. clearly established strategic real estate portfolio and management changes would ensure the satisfaction of public interests, ensure the appropriate financing sources, and encourage public–private partnerships. , (8) where: qf – total depreciation of a re object (%); qi – actual depreciation of ith element (%); ji – weight of ith element in the total value of the object (%); n – number of construction elements. the only advantage of this method is that it provides rather convincing results. yet, they are always subjective because of the different level of expert qualification. the estimation of depreciation by applying the method requires a great input of time, work and finances, which is why it is rarely used. another shortcoming is that its results quickly go out of date. moreover, such valuation very often skips the functional and external depreciation, which provides very little information to perform an accurate re object valuation. 4. conclusions there is still a lack of structured legislation or scientific research providing an integrated analysis and summary of peculiarities in municipal re classification, appraisal and management. the variety of classification means to classify the property and their incompatibility often cause inaccuracies in the structure and value of municipal re. not enough of attention is given to the estimation of actual value of municipal re. this is often limited to legislation and reports on the owned asset submitted by municipalities. to establish a reasonable ratio between the re objects for privatization generating one-off income, and those used to generate steady income (lease, management under the right of trust), the authors propose applying the municipal re current value ratio. if the buildings were evaluated and grouped under the classification and evaluation methodology provided by the authors and a database of the available municipal re was developed, the municipalities would be aware of the available type and amount of re they own, which would facilitate the estimation of the need for re to perform municipal functions. this classification allows adequate assessment of the existing municipal real estate portfolio and development of new rational alternatives. clearly established strategic real estate portfolio and management changes would ensure the satisfaction of public interests, ensure the appropriate financing sources, and encourage public–private partnerships. 72 references aleknavičius, a. 2008. nekilnojamojo turto vertinimas. vadovėlis. kaunas, ardiva, 188 p. deloitte real estate advisory (2011) municipal real estate. comparing public real estate management in european cities, p. 100. gasilionis, a., kasperavičius, r. 2006. nekilnojamojo turto administravimas. vilnius: všį lbk. http://dx.doi.org/10.3846/822-s halfawy, m. r. (2008) integration of municipal infrastructure asset management processes: challenges and solutions. journal of computing in civil engineering, 22(3), pp. 216–229. http:// dx.doi.org/10.1061/(asce)0887-3801(2008)22:3(216) kaganova, o., nayyar–stone, r. (2000) municipal real property asset management: an overview of world experience, trends and financial implications. journal of real estate portfolio management 6(4), pp. 307–326. lazdynas, r. 2005. savivalda: filosofija, teorija, praktika. šiauliai: saulės delta. 279 p. raslanas, s., tupėnaitė, l. 2007. individualių namų vertinimo ypatumai, taikant lyginamosios vertės metodą. http:// lt.lt.allconstructions.com/portal/categories/35/1/0/1/ article/1436/individualiu-namu-vertinimo-ypatumaitaikant-lyginamosios-vertes-metoda. [retrieved 22-122013]. savivaldybių organizuojamų viešųjų paslaugų teikimo analizė. 2010. http://www.vrm.lt/fileadmin/padaliniu_failai/viesojo_ administravimo_dep/2010/tyrimas.vp.galutinis.doc [retrieved 22-12-2013]. šulija v. 2009. turto masinio vertinimo ir apmokestinimo, mokestinės vertės tikslinimo teisiniai aspektai. turto vertinimo teorijos ir praktikos apybraizos, vilnius, p. 29–37. valstybės žinios, 2005. lr vyriausybės 2005 m. rugsėjo 29 d. nutarimas nr. 1049 „dėl nekilnojamojo turto vertinimo taisyklių patvirtinimo“. nr. 76-2741. zukauskas, v. (2011). lietuvos savivaldybių indeksas 2011, lietuvos laisvosios rinkos institutas, p. 84. http://www. savivaldybes.lt/savivaldybe, [retrieved 22-12-2013]. received 2014 02 10 accepted after revision 2014 02 24 eglė klumbytė – ph.d. student at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. assistant at kaunas university of technology, faculty of civil engineering and architecture, department of civil engineering technologies. main research area: municipal real estate strategic management. address: kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu str. 48, lt-51367. tel.: +370 683 27736 e-mail: egleklumbyte@gmail.com raimondas bliūdžius – professor at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. main research area: normalization of heat losses in buildings, thermal insulation of building enclosure, research of the properties of building thermal insulation materials. address: kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu str. 48, lt-51367. tel.: +370 37 350799 e-mail: raimondas.bliudzius@ktu.lt 74 study achievement of deep excavations from the point of view of their effects on surrounding existing buildings cosmin fantaziu*, răzvan chirilă * engineer, department of transportation infrastructure and foundations,”gheorghe asachi” technical university iasi, faculty of civil engineering and building services, iasi, 700050, romania. *corresponding author: fantaziucosmin@yahoo.com http://dx.doi.org/10.5755/j01.sace.7.2.6857 starting from concrete situations encountered in the city of iasi,romania, are presented the methods used by the authors to assess the influence siting of new construction in urban areas, densely built. the results are compared with measurements made to support deep excavation and settlements for new buildings and those are in the “zone of influence” them. proposals are to regulate the obligations of owners to ensure a minimum strength and stability of existing buildings and acceptable limits must fall within which influence design a new structure. keywords: deep excavations, influence, settlements, source of risk, surrounding existing buildings. 1. introduction density urban growth leads to the need to build tall buildings with deep foundations, positioning the car parks and other facilities in their basements. with the increasing trend of the depth of the foundation of these buildings is highlighted and the need to work to support the earth, larger and more rigid. this trend is reinforced by the need for founding the less compressible soil layers and the desire to create spaces to facilitate positioning of underground utilities and underground parking. there are numerous sources of risk (hazards) associated with performing deep excavations in urban areas, sources which must be considered in the design and execution of these works for any additional costs to a minimum. by “sources of risk” means the risk factors that generate and which can lead to poor design of enclosures, thus affecting neighboring buildings. the assessment of risk sources for disposal may occur additional measures and expenditure in the design and implementation enclosure excavated, that investor is forced to bear. the beneficiary is required to submit the approval to obtain building permits, at least two alternatives, one of which present minimal technical risk. the shape and dimensions in plan and excavation depth can be sources of risk. a large irregular outline and plan of excavation increases the complexity of support. the higher the trench depth, increase the difficulties of achieving not only work but also risks for themselves or for construction work in the neighborhood, to their stability, to be taken into account. analysis of deep excavation is required, usually before the start of the design process. this is a typical problem of soil-structure interaction. earth is a nonlinear material, inelastic and anisotropic behavior is strongly influenced by the presence of pore water. some types of soils presents properties of consolidation and creep. theoretical analysis of deep excavations involving simulations of elasto-plastic behavior of the earth, behavior interface between land and retaining walls as well as the process of excavation. some theories test are not fully developed and some are too complicated to be used in the practice of the design. thus, the current state is not practical analysis solely to contemporary theories and reasonable analysis of excavation would have to resort to means of classical mechanics of soils. 2. area of influence of deep excavations influence area of a building is defined in “norms on the principles, requirements and methods of research geotechnical soil” (np 074/2002) as “the amount of land that is felt the influence of those construction or phenomena that may occur to influence the construction”. deep trench designer will determine the area of influence of excavation, given the choice to all stages of execution of the works and shall specify measures to be taken for the safety of construction in the area of influence, whose stability and deformations should not be affected. this area will be detailed design, taking into account the chosen solution and all stages of completion, while ensuring that stability is assured everywhere and admissible deformations. darnioji architektūra ir statyba 2014. no. 2(7) journal of sustainable architecture and civil engineering issn 2029–9990 75 3. purpose and objectives this article aims to analyze the influence of parameters that control the performance of deep excavations in terms of their effects on adjacent existing buildings. for this purpose, analyzes the influence of existing buildings on the answer excavations new surrounding them. as relationship-building adjacent excavation is considered biunivocal, taking into account the effects on the behavior of deep excavations achieve neighboring buildings. it is noted that, due to lack of experience, combined with in situ measurements from photographs containing deep excavations made in the vicinity of the existing structure (mostly civil) technical regulations mentioned period shall not include requirements or methods for evaluating the effect of the execution and loads transmitted by the new construction on adjacent buildings. defining the existence of a zone of influence of any building in the ground in conjunction with european norm eurocode 7 geotechnical design – part 1 recently adopted as a romanian standard, draws attention to the need to take account of all phenomena that can occur foundation soil and influence on neighboring buildings are in this area. for deep excavations for construction factors that can significantly influence the existing buildings in the neighborhood are related both execution (excavation works to support, dewatering, etc.) and the load transmitted by the new structure. in the following we present some possibilities of treating this complex problems based on the methods soils mechanics and recommendations contained in technical regulations and reference works in the country and abroad. 4. practic determination area influence of a building and interaction with existing structures 4.1. the main components of settlements induced in soil by achieve a building for strength and stability of existing buildings in the area of influence of the new structure are significant size and time evolution of subsidence (vertical displacements, fig. 1) induced in the ground for the new building. plastic deformations from active and pasive zones afferent on a support action also induce local travel, reported by bransby and milligan (1975) as due to deformation in undrained conditions in the area defined by line basis of 45 ° inclination support. in this area, any point is considered to have an equal component displacement vertically and horizontally, resulting in deformation of the land surface. in most cases, additional settlements s were caused by construction and loading the new structure, in the adjacent land, consists of the following components: s = s1 + sh + s2 (1) where: s1 – settlements caused by excavation execution; sh – settlements caused by groundwater regime change (dewatering, etc.); s2 – settlements caused due to loading transmitted to the new building. 3. purpose and objectives this article aims to analyze the influence of parameters that control the performance of deep excavations in terms of their effects on adjacent existing buildings. for this purpose, analyzes the influence of existing buildings on the answer excavations new surrounding them. as relationship-building adjacent excavation is considered biunivocal, taking into account the effects on the behavior of deep excavations achieve neighboring buildings. it is noted that, due to lack of experience, combined with in situ measurements from photographs containing deep excavations made in the vicinity of the existing structure (mostly civil) technical regulations mentioned period shall not include requirements or methods for evaluating the effect of the execution and loads transmitted by the new construction on adjacent buildings. defining the existence of a zone of influence of any building in the ground in conjunction with european norm eurocode 7 geotechnical design part 1 recently adopted as a romanian standard, draws attention to the need to take account of all phenomena that can occur foundation soil and influence on neighboring buildings are in this area. for deep excavations for construction factors that can significantly influence the existing buildings in the neighborhood are related both execution (excavation works to support, dewatering, etc..) and the load transmitted by the new structure. in the following we present some possibilities of treating this complex problems based on the methods soils mechanics and recommendations contained in technical regulations and reference works in the country and abroad. 4. practic determination area influence of a building and interaction with existing structures a. the main components of settlements induced in soil by achieve a building for strength and stability of existing buildings in the area of influence of the new structure are significant size and time evolution of subsidence (vertical displacements, fig. 1) induced in the ground for the new building. plastic deformations from active and pasive zones afferent on a support action also induce local travel, reported by bransby and milligan (1975) as due to deformation in undrained conditions in the area defined by line basis of 45 ° inclination support. in this area, any point is considered to have an equal component displacement vertically and horizontally, resulting in deformation of the land surface. in most cases, additional settlements s were caused by construction and loading the new structure, in the adjacent land, consists of the following components: s=s 1 +s h +s 2 (1) where: s 1 settlements caused by excavation execution; s h -settlements caused by groundwater regime change (dewatering, etc.); s 2 settlements caused due to loading transmitted to the new building. a) decompression bottom of the pit and its swelling; b) the emergence recompression and compression land settlements; c) time variation of the foundation soil loading or pressure to consolidate; d) strain curve of the ground foundation during and after its execution. fig.1. evolution of foundation settlements in connection with the execution of the construction stages. of course, in the particular circumstances in connection with the foundation soil or construction of the new module can occur and other influencing factors (wetting layers sensitive dampening effect on the overall stability of the terrain, dynamic effects, etc.). the following describes some simplified methods for assessing settlements components of eq. (1). b. simplified methods for evaluating the area of influence and settlements therein 4.2.1. subsidence due to deformation work support component s 1 a) support embedded in the excavation. this system of support is justified, in our country geotechnical conditions for construction with 1...2 basements, when excavation (depth d f < 5...6 m) does not fall below the groundwater level (fig. 2). support can be made of rows of piles (cvasitangents, with interspaces) or of "berlin" (fig. 2). prisma land that produces active pressure p a defines the support and influence of the excavation area (distance l i ). to ensure fitting in the base of excavation must be carried out under p p mobilize passive resistance (or a fraction thereof to limit deformations). it is known that the movement toward massive wall to fully mobilize p p value is relatively high, even for compact soil: between 0,05 d p and 0,10 d p (as recommended by the european standard eurocode 7). in exchange for the mobilization of resistance equal to 0,5 p p required much smaller displacements δ f = (0,01 ... 0,02) d p . a) decompression bottom of the pit and its swelling; b) the emergence recompression and compression land settlements; c) time variation of the foundation soil loading or pressure to consolidate; d) strain curve of the ground foundation during and after its execution. fig. 1. evolution of foundation settlements in connection with the execution of the construction stages of course, in the particular circumstances in connection with the foundation soil or construction of the new module can occur and other influencing factors (wetting layers sensitive dampening effect on the overall stability of the terrain, dynamic effects, etc.). the following describes some simplified methods for assessing settlements components of eq. (1). 4.2. simplified methods for evaluating the area of influence and settlements therein 4.2.1. subsidence due to deformation work support – component s1 support embedded in the excavation. this system of support is justified, in our country geotechnical conditions for construction with 1...2 basements, when excavation (depth df < 5...6 m) does not fall below the groundwater level (fig. 2). support can be made of rows of piles (cvasitangents, with interspaces) or of „berlin” (fig. 2). prisma land that produces active pressure pa defines the support and influence of the excavation area (distance li). to ensure fitting in the base of excavation must be carried out under pp mobilize passive resistance (or a fraction thereof – to limit deformations). it is known that the movement toward massive wall to fully mobilize pp value is relatively high, even for compact soil: between 0,05 dp and 0,10 dp (as recommended by the european standard eurocode 7). in exchange for the mobilization of resistance equal to 0,5 pp required much smaller displacements δf = (0,01 ... 0,02) dp. 76 fig. 2. the area of influence of a support built in the base excavation since the settlement “s” trench adjacent land surface depends on the maximum horizontal displacement δmax wall appears reasonable to restrict the situation δf corresponding partial mobilization of passive pressure (most commonly from 0.5 pp). 4.2.2. lowering effect of hydrostatic level – component sh epuisment works, inherent to the excavations which falls below the hydrostatic groundwater production rate decreases outside contour trench, an enclosure is sealed and does not penetrate to the base in a waterproof layer. lowering the level of hydrostatic pressure has the effect of increasing geological layers below the initial share of groundwater, because the weight of the earth in the volume variation of water level increase for example the values γ ‘≈ 10kn/m3 (in submerged state) in γ = 18 ... 20 kn/m3. this increase vertical efforts lead to further subsidence layers to a depth appreciable, if clay layers, these settlements while building evolves over many months (depending on the thickness of the clay layer and the duration of maintenance work epuisment). it has two common situations for our country: ▪ when entering excavations 1...3 m below the hydrostatic appears rational development of small walled enclosure depth (or set in impermeable clay layer) and the first epuisment aquifer. ▪ in the case of deep excavations (building basements with 4...6 levels), the trench penetrates into the clay layer, but due to the negative pressure exerted on the bottom thereof in a confined stream of the second layer is necessary to perform some pumping depth . 4.2.3. the effect of loading the new building – component s2 load transmitted foundation of the new building system produces deformations in the ground that extend outside its footprint. in fig. 3 presents, indicative volume of soil in which vertical compression efforts lead to significant subsidence current cases. of course the size of the “bulb effect” varies according to the pressure “p” transmitted by the new foundation and the parameters of the deformation of the coating. current methods for calculating permit evaluation with acceptable accuracy, the subsidence caused by the new structure, taking into account the influence of the depth of the foundation, the presence of piles (in case of mixed foundation systems) etc.. fig. 3. vertical line equal effort (σz) under a continuous foundation 4.3. improved methods for calculating the deformation field in the phases of excavation and loading deformations that occur in the ground after sustaining cooperation with the massive wall of earth in various stages of implementation of excavation and lining of supporting and following discharge caused by excavation and loading provided by the new construction can be assessed using accepted computational models in mechanics lands. calculation methods that shape the successive stages of excavation, installation of ground support and load of the soil with new building load allows both evaluation efforts and strains in the supporting structure and the adjacent field trips (settlements caused in the surrounding areas). this enables the designer to “correct” any excessive subsidence on the wall supporting interventions (changing stiffness of the points of support, prestressing bars, and so on). 5. example to highlight the above will illustrate a practical case it is necessary to support the walls of the excavation in urban areas of jassy (iasi). the site is bordered on two sides by construction p +1e and the other two sides are bounded by streets serving public traffic. it wants to make an enclosure to support infrastructure construction of buildings for deployed underground parking on two levels. given the great height of the excavation was adopted solution with diaphragm walls support beam 40 cm in section. given the desire of the beneficiary to perform an excavation at a depth of 7.40 m above ground level in order 77 to implement the project and to meet the design requirements of regulations encompassing special geotechnical works by active and passive thrusts that develop behind, or in front of the wall, was measured by a predimensioning, the minimum depth of the recess of the wall in the ground equal to 9.00 m fig. 4. pressure diagrams, moments and movements in land case recessed wall it follows a long trench wall support at least 16.40 m given the neighborhood at distances close to the site, special attention is required regarding maximum allowable movements acceptable to not induce further work in the existing building foundations. due to the complexity of the problem for a more accurate approach to the calculation adopted by numerical solutions based on finite element method (fem) using computer programs (in this case plaxis 25) that can provide a consistent manner, because of the possibilities of modeling a design all the necessary data rigorous. 5.1. geotechnical characteristics of the soil: plaxis 25 table 1. geotechnical characteristics of the soil layer layer thick. γ [kn/m3] c [kpa] φ [o] sr [%] e [kpa] topsoil 1.00 18.00 10 15 0.81 6000 black silty clay 2.00 18.83 37 10 0.85 18700 clay powder 2.00 17.95 14 16 0.88 18500 brown silty clay 2.00 18.34 20 15 0.87 19600 brown clay powder 13.00 18.44 5 15 0.9 18500 the groundwater was intercepted at a depth of -11.00 m from ground level. 5.2. characteristics of materials tabel 2. characteristics of materials name of the object ea [kn/m] γ [kn/m3] ei [knm2/m] ν wall moldings 1.2*107 25.00 1.6*106 0.2 existing foundation 1.0*1010 22.00 1.0*109 0.2 5.3. modelling by finite element method fig. 5. geometry model fig. 6. meshing in finite element model created 5.4. results and their interpretation 5.4.1. running calculations pursuing technological phases of execution of the work were considered three stages of construction: a) execution of diaphragm walls and consideration of existing construction loads – determining the initial efforts of the ground massif; b) implementation of the excavation until the rate provided in the project; c) determination of safety factor by the criterion of shear strength parameters are reduced to overcome resistance to shear. a) c) d) b) 78 5.4.1.1. stage 1 ▪ horizontal and vertical displacements of diaphragm wall a) b) fig. 7. displacements: a) horizontals and b) verticals of diaphragm wall ▪ horizontal and vertical displacements of existing foundation a) b) fig. 8. displacements: a) horizontals and b) verticals of existing foundation 5.4.1.2. stage 2 fig. 9. deformed structure ▪ horizontal and vertical displacements of diaphragm wall a) b) fig. 10. displacements: a) horizontals and b) verticals of diaphragm wall 79 ▪ horizontal and vertical displacements of existing foundation a) b) fig. 11. displacements: a) horizontals and b) verticals of existing foundation ▪ efforts in curved wall a) b) c) fig. 12. efforts in curved wall: a) axial force, b) shear force, c) bending moment 5.4.1.3. stage 3 fig. 13. safety factor fs offered by the resistance structure (diaphragm wall) fig. 14. the area of influence of the excavation 6. conclusions to reduce the risk of failure (ultimate limit state) of deep excavations and damage to adjacent buildings (serviceability limit state) support design work should be done through detailed analysis of deformation and verification by several methods (semi-)empirical and simple analytical. thus, it is required a detailed understanding of how deformation and the mechanism for the transfer of land adjacent to the massive efforts in the construction works. this paper addresses the issue of estimating the earth movements around deep excavations. first, it analyzes the influence of adjacent excavation construction features through a parametric study on a characteristic pattern. its dimensions are set about statistics, the analysis of a comprehensive database on retaining walls of excavations and movements induced by them. on the other hand, this is analyzed based on real case studies posed by deep excavations densely built. the main objective of the article is the observation of deformation mechanisms based on the analysis of deformation-induced lateral displacements of the supporting walls of excavations. 80 references bransby p. l. & milligan g.w.e. 1975. soil deformation near cantilever sheet pile walls. géotechnique, vol. 25, pp 175– 195. http://dx.doi.org/10.1680/geot.1975.25.2.175 murugamoorthy c., kho c.m., vaidya b.g. & tang s.k., subramanian t. 2003. behaviour of various support systems for deep excavations, changi airport underground mrt station, rts conference, singapore. michael l., dr. mike l.2007. deep excavations in dublin recent developments, geotechnical society of ireland at engineers ireland. phung d. l., bredenberg h. 2000. a flexible drilled pile wall for deep excavation in copenhagen. pappin j., endicott j., clark j.. deep excavation in hong kong – design and construction control, presentation. gue s. s. & tan y. c. 1998. design and construction considerations for deep excavation, ssp geotechnics sdn bhd. toru masuda. 1982. behavior of deep excavation with diaphragm wall, hokkaido university. godavarthi v. r., mallavalli d., peddi r., katragadda n., mulpuru p. 2011. contiguous pile wall as a deep excavation supporting system, leonardo electronic journal of practices and technologies. ergun m. ufuk. 2008. deep excavations, department of civil engineering, middle east technical university, ankara, turkey. bauduin c. 2003. uncertainties and their relevance for the design of deep excavations near existing structures, xiiième european conference on soil mechanics and geotechnical engineering, prague. arbanas, ž., kovačević, m.-s., szavits-nossan, v. 2006. interactive design for deep excavations, xiii danubeeuropean conference on geotechnical engineering, ljubljana, slovenia. np 074/2002. normativ privind principiile, exigenţele şi metodele cercetării geotehnice a terenului de fundare. sr en 1997-1 (mai 2006). eurocod 7; proiectarea geotehnică. partea 1: reguli generale. stanciu, a., lungu, i. 2006 fundaţii. fizica şi mecanica pământurilor, bucureşti. stas 3300/2-85. teren de fundare. calculul terenului de fundare în cazul fundării directe. received 2014 04 02 accepted after revision 2014 05 13 cosmin fantaziu – department of transportation infrastructure and foundations,”gheorghe asachi” technical university iasi, faculty of civil engineering and building services, iasi, 700050, romania. main research area: geotechnical engineering. address: iasi, romania. tel.: +40 765652876 e-mail: fantaziucosmin@yahoo.com razvan chirila – department of transportation infrastructure and foundations,”gheorghe asachi” technical university iasi, faculty of civil engineering and building services, iasi, 700050, romania. main research area: geotechnic engineering. address: iasi, romania. tel.: +40 742085262 e-mail: razvan_fcs@yahoo.com 59 journal of sustainable architecture and civil engineering 2014/4/9 jsace 4/9 analysis of cracking moment of flexural elements reinforced by steel and frp reinforcement received 2014/06/30 accepted after revision 2014/10/02 journal of sustainable architecture and civil engineering vol. 4 / no. 9 / 2014 pp. 59-66 doi 10.5755/j01.sace.9.4.7428 © kaunas university of technology mindaugas augonis*, mindaugas kasiulevičius, rėda bistrickaitė kaunas university of technology, faculty of civil engineering and architecture, department of building structures studentu st. 48, lt-51367 kaunas, lithuania *corresponding author: mindaugas.augonis@ktu.lt analysis of cracking moment of flexural elements reinforced by steel and frp reinforcement http://dx.doi.org/10.5755/j01.sace.9.4.7428 robertas balevičius vilnius gediminas technical university, faculty of civil engineering, department of reinforced concrete and masonry structures sauletekio al. 11, lt-10223 vilnius, lithuania the application of frp reinforcement in concrete structures is quite popular nowadays. in this article the cracking moment of flexural concrete structures reinforced by steel and frp reinforcement bars is investigated. there is estimated that the behaviour of tensile concrete is nonlinear when crack opens. the nonlinearity was estimated by two different cases. in the first one the coefficient of elastic and plastic strain of tensile concrete were applied and in the second the stress-strain relationship were expressed by polynomial function. that function prepared according to compressed concrete stress-strain diagram described in design standard en 1992-1-1. those two different stress-strain relationships were used for cracking moment calculation. also the cracking moment calculations were performed using mentioned standard en and technical building code str 2.05.05:2005. in all cases the calculations were performed in assumption that the behaviour of compressed concrete is elastic when crack opens. the obtained results were analysed and presented base conclusions. keywords: frp reinforcement, cracking moment, stress-strain relationship, nonlinear behaviour, tensile concrete. introduction the steel as base reinforcement in reinforced concrete structures is used many years, however it properties satisfy not all requirements to reinforcement, especially the requirements of resistance to corrosion. for this reason the durability of concrete reinforced by steel reinforcement is not so high in aggressive condition to corrosion (abdala 2002, al-sunna, 2012, toutanji 2003). nowadays the low durability problem could be solving applying the new type of reinforcement in concrete structures i.e. the frp (fiber reinforced polymer) reinforcement which has higher tensile strength and higher resistance to corrosion (barrs el.al. 2012, barris et.al 2009, ashour 2006). such type of reinforcement could be used in concrete structures as reinforcement bars, meshes or reinforcing cages. the application of frp reinforcement in concrete structures of buildings, engineering works or underground works increase the durability of them and resistance to various damages. journal of sustainable architecture and civil engineering 2014/4/9 60 however such type of reinforcement has lower elasticity and worse anchorage with concrete. the modulus elasticity of frp reinforcement is several or more times less than modulus of steel. for this reason the stiffness and cracking problem arises to the flexural structures because into the cracked section the tensile forces are permitted only by tensile reinforcement. in this case into the concrete structures reinforced by frp reinforcement the cracking moment will be reached earlier and the deflection will be higher in comparing with simply reinforced structures. so, it could be concluded that high tensile strength of frp reinforcement in flexural structures could not be exhaust because of too high deformability and application so not effective economically and structurally. in that case frp reinforcement could be used with steel reinforcement together in order to increase the durability of structures. because of different elasticity the stress in steel reinforcement will be higher than in frp and the strength of structures significantly depend on amount and strength of steel reinforcement. but amount of steel reinforcement has no such significantly effect on cracking moment because it more depends on the concrete tensile strength and dimensions of cross section. for example according to principles of design standard en 1992-1-1:2004 the amount of reinforcement has no effect on cracking moment (mosley 2007) also the frp reinforcement is more brittle in compare with steel. so, the application of such reinforcement into the bridges structures could be limited. the frp reinforcement bar consists from the material (glass or basalt) strands of fibers connected by polymers (http://www.schoeck-combar.com, http://galen.su). such structure of fibers materials describes the high strength that could be several or more times higher than strength of solid cross section materials. the frp reinforcement has high strength in longitudinal direction. because of high resistance to alkalinity medium in concrete the frp reinforcement durability is about 100 year and more. it should be mentioned that the bond between concrete and steel reinforcement is better than frp reinforcement but in this article it is not investigated. the reinforcement could be in different types. the most popular is gfrp (glass fiber reinforced polymer) and basalt fiber reinforcement, but gfrp reinforcement more use in concrete structures because of less price. the main properties of gfrp and basalt fiber reinforcement are presented in table 1. review of main properties of frp reinforcement characteristics of materials steel reinforcement s400 class gfrp reinforcement „schőck combar“ gfrp reinforcement „rockbar“ bazalt fiber reinforcement „rockbar“ tensile strength mpa 360 1200 1000 1200 density, t/m3 7 2,2 2,0 2,0 corrosion corrosion materals no corrosion material satisfy to the first group of chemical resistance length of reinforcement product, m bars of 6-12m length bars of 10-14m length bars until 12m length elastic modulus, n/mm2 200000 60000 45000 50000-55000 cover, mm according to codes, str ø+10mm, for precast reinforced concrete ø+5mm table 1 the main propeties of steel and frp reinforcement (http:// www.schoeck-combar. com, http://galen.su) 61 journal of sustainable architecture and civil engineering 2014/4/9 in this investigation the concrete stress-strain relationship were expressed in two cases. 1 case. analysing the elastic plastic behaviour of tensile concrete should be note that c c σ ε− relationship could have quite significant influence to the crack moment crcm . the ec2 standard presents c c σ ε− relation for compressed concrete but not describe the tensile concrete. if to assume that ultimate strain of tensile concrete correspond the ultimate tensile stress ( )ctmf , and the form of tensile concrete c c σ ε− curve correspond to the form of compressed concrete until the peak of stress, it is possible to apply the ec2 standard expression of stress-strain relationship. in all figures the font of text are changed in “times new roman” and in fig. 1 and fig. 2 are presented units of tensile stress so, if to calculate the tensile stress basalt fiber reinforcement, but gfrp reinforcement more use in concrete structures because of less price. the main properties of gfrp and basalt fiber reinforcement are presented in table 1. 1 lentelė. the main propeties of steel and frp reinforcement (http://www.schoeck-combar.com, http://galen.su) 3. the tensile concrete stress-strain relationship in this investigation the concrete stress-strain relationship were expressed in two cases. 1 case. analysing the elastic plastic behaviour of tensile concrete should be note that c c σ ε− relationship could have quite significant influence to the crack moment crc m . the ec2 standard presents c c σ ε− relation for compressed concrete but not describe the tensile concrete. if to assume that ultimate strain of tensile concrete correspond the ultimate tensile stress ( ) ctm f , and the form of tensile concrete c c σ ε− curve correspond to the form of compressed concrete until the peak of stress, it is possible to apply the ec2 standard expression of stress-strain relationship. in all figures the font of text are changed in “times new roman” and in fig. 1 and fig. 2 are presented units of tensile stress fig. 1. the tensile concrete stress-strain relationship when the ec2 standard expression is used. concrete class c40/50. so, if to calculate the tensile stress ct σ directly according to the ec2 standard expression rewriting the ctm f instead of cm f only, we will obtain: ( ) 2 1 2 ct ctm k f k η η σ η ⎛ ⎞− = ⎜ ⎟ ⎜ ⎟ + − ⎝ ⎠ , (1) where 1 1 05 cm ct, ctm k , e / fε= , 0 31 1 0 0007 ctm . ct, , fε = . according such way drawing up the c c σ ε− relationship of tensile concrete we will obtain the curve that form at all will not be similar to the form of curve of compressed concrete (fig. 2). in this case the curves forms not correspond each other because of different values of the ratios 1 cm c, f ε and 1 ctm ct, f ε . for example to the concrete class 20 25 c the numerical values is: 28 cm f mpa= ; 1 0 001967 c, ,ε = , 2 21 ctm f , mpa= , 4 1 8 95 10 ct, ,ε − = ⋅ . then we obtain that the ratio of 1 14234 875 cm c, f , ε = and 1 2469 273 ctm ct, f , ε = differ more than six times. also, according such case the secant modulus of compressed concrete at the peak stress ( ) ct ctm fσ = was 5,765 times bigger than to the tensile concrete. if to express the ultimate elastic plastic coefficient at the stress peak it would obtained the 0 475,λ = to the compressed concrete and only the 0 0842 ct ,λ = to the tensile concrete. if to assume the one and the same elastic plastic coefficient to the compressed and tensile concrete, the strain at the peak stress 1ct, ε should be expressed with different factor as 0 31 1 0 000121 ctm , ct, f ,ε = . this factor, of course, depend on the ctm f , so, to the characteristics of materials steel reinforcement s400 class gfrp reinforcement „schőck combar“ gfrp reinforcement „rockbar“ bazalt fiber reinforcement „rockbar“ tensile strength mpa 360 1200 1000 1200 density, t/m 3 7 2,2 2,0 2,0 corrosion corrosion materals no corrosion material satisfy to the first group of chemical resistance length of reinforcement product, m bars of 6-12m length bars of 10-14m length bars until 12m length elastic modulus, n/mm 2 200000 60000 45000 50000-55000 cover, mm according to codes, str ø+10mm, for precast reinforced concrete ø+5mm directly according to the ec2 standard expression rewriting the ctmf instead of cmf only, we will obtain: the tensile concrete stress-strain relationship according such way drawing up the c c σ ε− relationship of tensile concrete we will obtain the curve that form at all will not be similar to the form of curve of compressed concrete (fig. 2). in this case the curves forms not correspond each other because of different values of the ratios 1 cm c , f ε and 1 ctm ct , f ε . for example to the concrete class 20 25c the numerical values is: 28cmf mpa= ; 1 0 001967c , ,ε = , 2 21ctmf , mpa= , 4 1 8 95 10ct , ,ε −= ⋅ . then we obtain that the ratio of 1 14234 875cm c , f ,ε = and 1 2469 273ctm ct , f ,ε = differ more than six times. also, according where: (1) basalt fiber reinforcement, but gfrp reinforcement more use in concrete structures because of less price. the main properties of gfrp and basalt fiber reinforcement are presented in table 1. 1 lentelė. the main propeties of steel and frp reinforcement (http://www.schoeck-combar.com, http://galen.su) 3. the tensile concrete stress-strain relationship in this investigation the concrete stress-strain relationship were expressed in two cases. 1 case. analysing the elastic plastic behaviour of tensile concrete should be note that c c σ ε− relationship could have quite significant influence to the crack moment crc m . the ec2 standard presents c c σ ε− relation for compressed concrete but not describe the tensile concrete. if to assume that ultimate strain of tensile concrete correspond the ultimate tensile stress ( ) ctm f , and the form of tensile concrete c c σ ε− curve correspond to the form of compressed concrete until the peak of stress, it is possible to apply the ec2 standard expression of stress-strain relationship. in all figures the font of text are changed in “times new roman” and in fig. 1 and fig. 2 are presented units of tensile stress fig. 1. the tensile concrete stress-strain relationship when the ec2 standard expression is used. concrete class c40/50. so, if to calculate the tensile stress ct σ directly according to the ec2 standard expression rewriting the ctm f instead of cm f only, we will obtain: ( ) 2 1 2 ct ctm k f k η η σ η ⎛ ⎞− = ⎜ ⎟ ⎜ ⎟ + − ⎝ ⎠ , (1) where 1 1 05 cm ct, ctm k , e / fε= , 0 31 1 0 0007 ctm . ct, , fε = . according such way drawing up the c c σ ε− relationship of tensile concrete we will obtain the curve that form at all will not be similar to the form of curve of compressed concrete (fig. 2). in this case the curves forms not correspond each other because of different values of the ratios 1 cm c, f ε and 1 ctm ct, f ε . for example to the concrete class 20 25 c the numerical values is: 28 cm f mpa= ; 1 0 001967 c, ,ε = , 2 21 ctm f , mpa= , 4 1 8 95 10 ct, ,ε − = ⋅ . then we obtain that the ratio of 1 14234 875 cm c, f , ε = and 1 2469 273 ctm ct, f , ε = differ more than six times. also, according such case the secant modulus of compressed concrete at the peak stress ( ) ct ctm fσ = was 5,765 times bigger than to the tensile concrete. if to express the ultimate elastic plastic coefficient at the stress peak it would obtained the 0 475,λ = to the compressed concrete and only the 0 0842 ct ,λ = to the tensile concrete. if to assume the one and the same elastic plastic coefficient to the compressed and tensile concrete, the strain at the peak stress 1ct, ε should be expressed with different factor as 0 31 1 0 000121 ctm , ct, f ,ε = . this factor, of course, depend on the ctm f , so, to the characteristics of materials steel reinforcement s400 class gfrp reinforcement „schőck combar“ gfrp reinforcement „rockbar“ bazalt fiber reinforcement „rockbar“ tensile strength mpa 360 1200 1000 1200 density, t/m 3 7 2,2 2,0 2,0 corrosion corrosion materals no corrosion material satisfy to the first group of chemical resistance length of reinforcement product, m bars of 6-12m length bars of 10-14m length bars until 12m length elastic modulus, n/mm 2 200000 60000 45000 50000-55000 cover, mm according to codes, str ø+10mm, for precast reinforced concrete ø+5mm basalt fiber reinforcement, but gfrp reinforcement more use in concrete structures because of less price. the main properties of gfrp and basalt fiber reinforcement are presented in table 1. 1 lentelė. the main propeties of steel and frp reinforcement (http://www.schoeck-combar.com, http://galen.su) 3. the tensile concrete stress-strain relationship in this investigation the concrete stress-strain relationship were expressed in two cases. 1 case. analysing the elastic plastic behaviour of tensile concrete should be note that c c σ ε− relationship could have quite significant influence to the crack moment crc m . the ec2 standard presents c c σ ε− relation for compressed concrete but not describe the tensile concrete. if to assume that ultimate strain of tensile concrete correspond the ultimate tensile stress ( ) ctm f , and the form of tensile concrete c c σ ε− curve correspond to the form of compressed concrete until the peak of stress, it is possible to apply the ec2 standard expression of stress-strain relationship. in all figures the font of text are changed in “times new roman” and in fig. 1 and fig. 2 are presented units of tensile stress fig. 1. the tensile concrete stress-strain relationship when the ec2 standard expression is used. concrete class c40/50. so, if to calculate the tensile stress ct σ directly according to the ec2 standard expression rewriting the ctm f instead of cm f only, we will obtain: ( ) 2 1 2 ct ctm k f k η η σ η ⎛ ⎞− = ⎜ ⎟ ⎜ ⎟ + − ⎝ ⎠ , (1) where 1 1 05 cm ct, ctm k , e / fε= , 0 31 1 0 0007 ctm . ct, , fε = . according such way drawing up the c c σ ε− relationship of tensile concrete we will obtain the curve that form at all will not be similar to the form of curve of compressed concrete (fig. 2). in this case the curves forms not correspond each other because of different values of the ratios 1 cm c, f ε and 1 ctm ct, f ε . for example to the concrete class 20 25 c the numerical values is: 28 cm f mpa= ; 1 0 001967 c, ,ε = , 2 21 ctm f , mpa= , 4 1 8 95 10 ct, ,ε − = ⋅ . then we obtain that the ratio of 1 14234 875 cm c, f , ε = and 1 2469 273 ctm ct, f , ε = differ more than six times. also, according such case the secant modulus of compressed concrete at the peak stress ( ) ct ctm fσ = was 5,765 times bigger than to the tensile concrete. if to express the ultimate elastic plastic coefficient at the stress peak it would obtained the 0 475,λ = to the compressed concrete and only the 0 0842 ct ,λ = to the tensile concrete. if to assume the one and the same elastic plastic coefficient to the compressed and tensile concrete, the strain at the peak stress 1ct, ε should be expressed with different factor as 0 31 1 0 000121 ctm , ct, f ,ε = . this factor, of course, depend on the ctm f , so, to the characteristics of materials steel reinforcement s400 class gfrp reinforcement „schőck combar“ gfrp reinforcement „rockbar“ bazalt fiber reinforcement „rockbar“ tensile strength mpa 360 1200 1000 1200 density, t/m 3 7 2,2 2,0 2,0 corrosion corrosion materals no corrosion material satisfy to the first group of chemical resistance length of reinforcement product, m bars of 6-12m length bars of 10-14m length bars until 12m length elastic modulus, n/mm 2 200000 60000 45000 50000-55000 cover, mm according to codes, str ø+10mm, for precast reinforced concrete ø+5mm basalt fiber reinforcement, but gfrp reinforcement more use in concrete structures because of less price. the main properties of gfrp and basalt fiber reinforcement are presented in table 1. 1 lentelė. the main propeties of steel and frp reinforcement (http://www.schoeck-combar.com, http://galen.su) 3. the tensile concrete stress-strain relationship in this investigation the concrete stress-strain relationship were expressed in two cases. 1 case. analysing the elastic plastic behaviour of tensile concrete should be note that c c σ ε− relationship could have quite significant influence to the crack moment crc m . the ec2 standard presents c c σ ε− relation for compressed concrete but not describe the tensile concrete. if to assume that ultimate strain of tensile concrete correspond the ultimate tensile stress ( ) ctm f , and the form of tensile concrete c c σ ε− curve correspond to the form of compressed concrete until the peak of stress, it is possible to apply the ec2 standard expression of stress-strain relationship. in all figures the font of text are changed in “times new roman” and in fig. 1 and fig. 2 are presented units of tensile stress fig. 1. the tensile concrete stress-strain relationship when the ec2 standard expression is used. concrete class c40/50. so, if to calculate the tensile stress ct σ directly according to the ec2 standard expression rewriting the ctm f instead of cm f only, we will obtain: ( ) 2 1 2 ct ctm k f k η η σ η ⎛ ⎞− = ⎜ ⎟ ⎜ ⎟ + − ⎝ ⎠ , (1) where 1 1 05 cm ct, ctm k , e / fε= , 0 31 1 0 0007 ctm . ct, , fε = . according such way drawing up the c c σ ε− relationship of tensile concrete we will obtain the curve that form at all will not be similar to the form of curve of compressed concrete (fig. 2). in this case the curves forms not correspond each other because of different values of the ratios 1 cm c, f ε and 1 ctm ct, f ε . for example to the concrete class 20 25 c the numerical values is: 28 cm f mpa= ; 1 0 001967 c, ,ε = , 2 21 ctm f , mpa= , 4 1 8 95 10 ct, ,ε − = ⋅ . then we obtain that the ratio of 1 14234 875 cm c, f , ε = and 1 2469 273 ctm ct, f , ε = differ more than six times. also, according such case the secant modulus of compressed concrete at the peak stress ( ) ct ctm fσ = was 5,765 times bigger than to the tensile concrete. if to express the ultimate elastic plastic coefficient at the stress peak it would obtained the 0 475,λ = to the compressed concrete and only the 0 0842 ct ,λ = to the tensile concrete. if to assume the one and the same elastic plastic coefficient to the compressed and tensile concrete, the strain at the peak stress 1ct, ε should be expressed with different factor as 0 31 1 0 000121 ctm , ct, f ,ε = . this factor, of course, depend on the ctm f , so, to the characteristics of materials steel reinforcement s400 class gfrp reinforcement „schőck combar“ gfrp reinforcement „rockbar“ bazalt fiber reinforcement „rockbar“ tensile strength mpa 360 1200 1000 1200 density, t/m 3 7 2,2 2,0 2,0 corrosion corrosion materals no corrosion material satisfy to the first group of chemical resistance length of reinforcement product, m bars of 6-12m length bars of 10-14m length bars until 12m length elastic modulus, n/mm 2 200000 60000 45000 50000-55000 cover, mm according to codes, str ø+10mm, for precast reinforced concrete ø+5mm ; basalt fiber reinforcement, but gfrp reinforcement more use in concrete structures because of less price. the main properties of gfrp and basalt fiber reinforcement are presented in table 1. 1 lentelė. the main propeties of steel and frp reinforcement (http://www.schoeck-combar.com, http://galen.su) 3. the tensile concrete stress-strain relationship in this investigation the concrete stress-strain relationship were expressed in two cases. 1 case. analysing the elastic plastic behaviour of tensile concrete should be note that c c σ ε− relationship could have quite significant influence to the crack moment crc m . the ec2 standard presents c c σ ε− relation for compressed concrete but not describe the tensile concrete. if to assume that ultimate strain of tensile concrete correspond the ultimate tensile stress ( ) ctm f , and the form of tensile concrete c c σ ε− curve correspond to the form of compressed concrete until the peak of stress, it is possible to apply the ec2 standard expression of stress-strain relationship. in all figures the font of text are changed in “times new roman” and in fig. 1 and fig. 2 are presented units of tensile stress fig. 1. the tensile concrete stress-strain relationship when the ec2 standard expression is used. concrete class c40/50. so, if to calculate the tensile stress ct σ directly according to the ec2 standard expression rewriting the ctm f instead of cm f only, we will obtain: ( ) 2 1 2 ct ctm k f k η η σ η ⎛ ⎞− = ⎜ ⎟ ⎜ ⎟ + − ⎝ ⎠ , (1) where 1 1 05 cm ct, ctm k , e / fε= , 0 31 1 0 0007 ctm . ct, , fε = . according such way drawing up the c c σ ε− relationship of tensile concrete we will obtain the curve that form at all will not be similar to the form of curve of compressed concrete (fig. 2). in this case the curves forms not correspond each other because of different values of the ratios 1 cm c, f ε and 1 ctm ct, f ε . for example to the concrete class 20 25 c the numerical values is: 28 cm f mpa= ; 1 0 001967 c, ,ε = , 2 21 ctm f , mpa= , 4 1 8 95 10 ct, ,ε − = ⋅ . then we obtain that the ratio of 1 14234 875 cm c, f , ε = and 1 2469 273 ctm ct, f , ε = differ more than six times. also, according such case the secant modulus of compressed concrete at the peak stress ( ) ct ctm fσ = was 5,765 times bigger than to the tensile concrete. if to express the ultimate elastic plastic coefficient at the stress peak it would obtained the 0 475,λ = to the compressed concrete and only the 0 0842 ct ,λ = to the tensile concrete. if to assume the one and the same elastic plastic coefficient to the compressed and tensile concrete, the strain at the peak stress 1ct, ε should be expressed with different factor as 0 31 1 0 000121 ctm , ct, f ,ε = . this factor, of course, depend on the ctm f , so, to the characteristics of materials steel reinforcement s400 class gfrp reinforcement „schőck combar“ gfrp reinforcement „rockbar“ bazalt fiber reinforcement „rockbar“ tensile strength mpa 360 1200 1000 1200 density, t/m 3 7 2,2 2,0 2,0 corrosion corrosion materals no corrosion material satisfy to the first group of chemical resistance length of reinforcement product, m bars of 6-12m length bars of 10-14m length bars until 12m length elastic modulus, n/mm 2 200000 60000 45000 50000-55000 cover, mm according to codes, str ø+10mm, for precast reinforced concrete ø+5mm concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim such case the secant modulus of compressed concrete at the peak stress ( )ct ctmfσ = was 5,765 times bigger than to the tensile concrete. if to express the ultimate elastic plastic coefficient at the stress peak it would obtained the 0 475,λ = to the compressed concrete and only the 0 0842ct ,λ = to the tensile concrete. if to assume the one and the same elastic plastic coefficient to the compressed and tensile concrete, the strain at the peak stress 1ct ,ε should be expressed with different factor as 0 311 0 000121 ctm , ct , f,ε = . this factor, of course, depend on the ctmf , so, to the concrete class from 810c to 50 60c the strain could be expressed with average factor: (2) concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim fig. 1 the tensile concrete stress-strain relationship when the ec2 standard expression is used. concrete class c40/50 fig. 2 the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve) journal of sustainable architecture and civil engineering 2014/4/9 62 then the member k to the tensile concrete would be obtained from the other equation when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal (3) concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim . (4) concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim where: where 1a , 2a , 3a – free members. (5) concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim the free members corresponded the stress-strain relationship of the c30/37 class concrete is ual to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim where concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim – ultimate value of the elastic plastic coefficient at the moment of failure; (6) concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim iε – strain; limε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , elε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as (7) concrete class from 8 10 c to 50 60 c the strain could be expressed with average factor: cm ctm ct f f 31.1 1, 00156.0 =ε . (2) then the member k to the tensile concrete would be obtained from the other equation 0.3 ,1 1.31 0.31 0.7 1.05 1.05 22000 10 0.00156 18.06 cmcm ct ctm ctm ctm cm cm ctm fe k f f f f f f ε − ⎛ ⎞ = = ⋅ ⋅ ⎜ ⎟ ⎝ ⎠ ⋅ = ⋅ . (3) when the ultimate concrete strain it is known the tensile stress could be expressed according to the adjusted ec2 equation: ( ) ( ) ctctmcmcmctm ctctmcmctcmctm ctm ct ffff ffff k k f ε εε η ηησ 31.17.031.0 262.223.012 206.186411 41091411577 21 −− −− −⋅+ − = −+ − = . (4) the tensile stress of concrete (class 40/50) obtained according to the equation (4) is presented in fig. 2 where the peak of stress is reached at the strain equal to 0.000165. fig. 2. the stress-strain relationship expressed according to the equation (4) (1-curve) and equation (1) (2-curve). the obtained expression (4) is not so convenient to the resultant calculation of the tensile and compressed concrete zones and to the crack moment also, because the strain member is in the denominator. such not well on calculation of integrals. in this case more convenient the tensile stress expressed by polynomials (židonis 2007, 2009, 2010). then the stress of tensile concrete will be equal 2 1 2 3ct ct ct a a aσ ε ε= ⋅ + ⋅ + , (5) where 1 a , 2 a , 3 a – free members. the free members corresponded the stress-strain relationship of the c30/37 class concrete is equal to: 1 105003697.6a = − , 2 34987.8a = , 3 0.0127a = . 2 case. it is also convenient to apply the elastic plastic coefficient λ to express the σ ε− relationship. if to assume that this coefficient linear vary from the beginning of elastic plastic zone until to concrete fracture it could be expressed as (augonis 2013) 1 i el lim lim el ε ε λ λ ε ε − = − − , (6) where lim λ – ultimate value of the elastic plastic coefficient at the moment of failure, i ε –strain, lim ε – ultimate strain (strain at the moment of failure) ( ) c lim lim c f e ε λ = , el ε – ultimate elastic strain 0 4 c el c , f e ε ≈ . then the tensile stress could be expressed as ctctcct e ελσ = . (7) the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctm f ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. fig. 3. the stress-strain relationship of tensile concrete ( 005ct ctk, f f= ). 1– when the elastic plastic coefficient 0 5 ct,lim ,λ = is applied, 2– when the equation (5) is applied with the factor 0,7. 4. the crack moment of members reinforced by steel reinforcement and frp reinforcement in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. ε ct,lim fig. 3 the stress-strain relationship of tensile concrete ( 005ct ctk ,f f= ). 1 – when the elastic plastic coefficient 0 5ct ,lim ,λ = is applied, 2 – when the equation (5) is applied with the factor 0,7 63 journal of sustainable architecture and civil engineering 2014/4/9 the stress-strain relationships expressed according to the equation (5) and equation (7) to the c30/37 class concrete is presented in fig. 3 where the are used not the average values of stress ( ctmf ) but characteristic values (fctk0,05). for this reason the factor 0,7 were applied to the values obtained by equation (5). according to that figure the curves is differ but it should be note that the ultimate strain is differ also. in this section the cracking moments are calculated with assumption that the behaviour of compressed concrete is elastic because not high the amount of reinforcement was predicted. for calculations the stress and strain schemes presented in fig. 4 were used. calculating the cracking moment of elements reinforced by frp reinforcement, were assumed that the bond between reinforcement and concrete is quite enough. when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ctct ,lim c f eε λ= (baikov 1991). in this case it is important right to evaluate the member limλ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ctct ,lim c f eε = . then the resultant of tensile concrete zone would be equal: the crack moment of members reinforced by steel reinforcement and frp reinforcement when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ct ct,lim c f e ε λ = (baikov 1991). in this case it is important right to evaluate the member lim λ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5 lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ct ct,lim c f e ε = . then the resultant of tensile concrete zone would be equal: ε x b a s ct,el ε ct ε s y xpl el x h c d m x ciε f ct,el σ σct ct,el f s ct,pl f c σ ci h f c fig. 4. strain and stress of element when compressive concrete behaviour is elastic. 1 2 el h x ct el c el ct ct c x f e b x e bε ε λ − = ⋅ ⋅ + ∫ . (8) so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct,lim ε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) ( ) ( ) ( ) ( )( ) ( ) ss c c elct ccc elctctelct elelctctelelct ccrc ae x xd xbexbe kxhkxh xx kxhbem 2 2 2 3 ,2 ,lim,, ,lim,, 3 1 3 1 24 5 3 34 3 − +++ + ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ −− + − + + − + −= ε ε ε ε εεε εεε , (9) where 1 ct,el c k ε ε = + , ct,el el c x x ε ε = , ct,lim c x h x ε ε = − . the height of the compressed zone is calculated according to the force equilibrium equation. according to the equation (9) obtained cracking moment results were compared with results according to the methods of standard ec2 and str for calculations were accepted the rectangular section beam with parameters: 0 2b . m= , 1 0 05d . m= , 200 s e gpa= , 50 k e gpa= , 30 c e gpa= , 2 10 s k a a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. fig. 5. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. fig. 6. the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. when the cracking moment is calculating according to the stress-strain expression (5) the resultant of the tensile concrete zone will be equal: ( ) 2 1 2 3 1 2 el h x ct el c el ct ct x f e b x b a a aε ε ε − = ⋅ ⋅ + ⋅ + ⋅ +∫ . (10) the calculation of cracking moment was performed analogically as before using the scheme presented in figure 4. the calculated cracking moment values according to the stress-strain expression (5) and expression (7) is presented in figure 7 and figure 8. the cracking moment obtained some higher when the polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0,0001656 ct ε = . in case when the expression (7) fig. 4 strain and stress of element when compressive concrete behaviour is elastic so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct ,limε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) (8) when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ct ct,lim c f e ε λ = (baikov 1991). in this case it is important right to evaluate the member lim λ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5 lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ct ct,lim c f e ε = . then the resultant of tensile concrete zone would be equal: ε x b a s ct,el ε ct ε s y xpl el x h c d m x ciε f ct,el σ σct ct,el f s ct,pl f c σ ci h f c fig. 4. strain and stress of element when compressive concrete behaviour is elastic. 1 2 el h x ct el c el ct ct c x f e b x e bε ε λ − = ⋅ ⋅ + ∫ . (8) so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct,lim ε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) ( ) ( ) ( ) ( )( ) ( ) ss c c elct ccc elctctelct elelctctelelct ccrc ae x xd xbexbe kxhkxh xx kxhbem 2 2 2 3 ,2 ,lim,, ,lim,, 3 1 3 1 24 5 3 34 3 − +++ + ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ −− + − + + − + −= ε ε ε ε εεε εεε , (9) where 1 ct,el c k ε ε = + , ct,el el c x x ε ε = , ct,lim c x h x ε ε = − . the height of the compressed zone is calculated according to the force equilibrium equation. according to the equation (9) obtained cracking moment results were compared with results according to the methods of standard ec2 and str for calculations were accepted the rectangular section beam with parameters: 0 2b . m= , 1 0 05d . m= , 200 s e gpa= , 50 k e gpa= , 30 c e gpa= , 2 10 s k a a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. fig. 5. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. fig. 6. the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. when the cracking moment is calculating according to the stress-strain expression (5) the resultant of the tensile concrete zone will be equal: ( ) 2 1 2 3 1 2 el h x ct el c el ct ct x f e b x b a a aε ε ε − = ⋅ ⋅ + ⋅ + ⋅ +∫ . (10) the calculation of cracking moment was performed analogically as before using the scheme presented in figure 4. the calculated cracking moment values according to the stress-strain expression (5) and expression (7) is presented in figure 7 and figure 8. the cracking moment obtained some higher when the polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0,0001656 ct ε = . in case when the expression (7) the height of the compressed zone is calculated according to the force equilibrium equation. according to the equation (9) obtained cracking moment results were compared with results according to the methods of standard ec2 and str for calculations were accepted the rectangular section beam with parameters: 0 2b . m= , 1 0 05d . m= , 200se gpa= , 50ke gpa= , 30ce gpa= , 210s ka a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: (9) when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ct ct,lim c f e ε λ = (baikov 1991). in this case it is important right to evaluate the member lim λ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5 lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ct ct,lim c f e ε = . then the resultant of tensile concrete zone would be equal: ε x b a s ct,el ε ct ε s y xpl el x h c d m x ciε f ct,el σ σct ct,el f s ct,pl f c σ ci h f c fig. 4. strain and stress of element when compressive concrete behaviour is elastic. 1 2 el h x ct el c el ct ct c x f e b x e bε ε λ − = ⋅ ⋅ + ∫ . (8) so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct,lim ε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) ( ) ( ) ( ) ( )( ) ( ) ss c c elct ccc elctctelct elelctctelelct ccrc ae x xd xbexbe kxhkxh xx kxhbem 2 2 2 3 ,2 ,lim,, ,lim,, 3 1 3 1 24 5 3 34 3 − +++ + ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ −− + − + + − + −= ε ε ε ε εεε εεε , (9) where 1 ct,el c k ε ε = + , ct,el el c x x ε ε = , ct,lim c x h x ε ε = − . the height of the compressed zone is calculated according to the force equilibrium equation. according to the equation (9) obtained cracking moment results were compared with results according to the methods of standard ec2 and str for calculations were accepted the rectangular section beam with parameters: 0 2b . m= , 1 0 05d . m= , 200 s e gpa= , 50 k e gpa= , 30 c e gpa= , 2 10 s k a a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. fig. 5. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. fig. 6. the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. when the cracking moment is calculating according to the stress-strain expression (5) the resultant of the tensile concrete zone will be equal: ( ) 2 1 2 3 1 2 el h x ct el c el ct ct x f e b x b a a aε ε ε − = ⋅ ⋅ + ⋅ + ⋅ +∫ . (10) the calculation of cracking moment was performed analogically as before using the scheme presented in figure 4. the calculated cracking moment values according to the stress-strain expression (5) and expression (7) is presented in figure 7 and figure 8. the cracking moment obtained some higher when the polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0,0001656 ct ε = . in case when the expression (7) when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ct ct,lim c f e ε λ = (baikov 1991). in this case it is important right to evaluate the member lim λ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5 lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ct ct,lim c f e ε = . then the resultant of tensile concrete zone would be equal: ε x b a s ct,el ε ct ε s y xpl el x h c d m x ciε f ct,el σ σct ct,el f s ct,pl f c σ ci h f c fig. 4. strain and stress of element when compressive concrete behaviour is elastic. 1 2 el h x ct el c el ct ct c x f e b x e bε ε λ − = ⋅ ⋅ + ∫ . (8) so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct,lim ε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) ( ) ( ) ( ) ( )( ) ( ) ss c c elct ccc elctctelct elelctctelelct ccrc ae x xd xbexbe kxhkxh xx kxhbem 2 2 2 3 ,2 ,lim,, ,lim,, 3 1 3 1 24 5 3 34 3 − +++ + ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ −− + − + + − + −= ε ε ε ε εεε εεε , (9) where 1 ct,el c k ε ε = + , ct,el el c x x ε ε = , ct,lim c x h x ε ε = − . the height of the compressed zone is calculated according to the force equilibrium equation. according to the equation (9) obtained cracking moment results were compared with results according to the methods of standard ec2 and str for calculations were accepted the rectangular section beam with parameters: 0 2b . m= , 1 0 05d . m= , 200 s e gpa= , 50 k e gpa= , 30 c e gpa= , 2 10 s k a a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. fig. 5. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. fig. 6. the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. when the cracking moment is calculating according to the stress-strain expression (5) the resultant of the tensile concrete zone will be equal: ( ) 2 1 2 3 1 2 el h x ct el c el ct ct x f e b x b a a aε ε ε − = ⋅ ⋅ + ⋅ + ⋅ +∫ . (10) the calculation of cracking moment was performed analogically as before using the scheme presented in figure 4. the calculated cracking moment values according to the stress-strain expression (5) and expression (7) is presented in figure 7 and figure 8. the cracking moment obtained some higher when the polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0,0001656 ct ε = . in case when the expression (7) ; where: 1 ct ,el c k ε ε = + ; ct ,el el c x x ε ε = ; ct ,limc x h x ε ε = − . , journal of sustainable architecture and civil engineering 2014/4/9 64 when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ct ct,lim c f e ε λ = (baikov 1991). in this case it is important right to evaluate the member lim λ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5 lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ct ct,lim c f e ε = . then the resultant of tensile concrete zone would be equal: ε x b a s ct,el ε ct ε s y xpl el x h c d m x ciε f ct,el σ σct ct,el f s ct,pl f c σ ci h f c fig. 4. strain and stress of element when compressive concrete behaviour is elastic. 1 2 el h x ct el c el ct ct c x f e b x e bε ε λ − = ⋅ ⋅ + ∫ . (8) so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct,lim ε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) ( ) ( ) ( ) ( )( ) ( ) ss c c elct ccc elctctelct elelctctelelct ccrc ae x xd xbexbe kxhkxh xx kxhbem 2 2 2 3 ,2 ,lim,, ,lim,, 3 1 3 1 24 5 3 34 3 − +++ + ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ −− + − + + − + −= ε ε ε ε εεε εεε , (9) where 1 ct,el c k ε ε = + , ct,el el c x x ε ε = , ct,lim c x h x ε ε = − . the height of the compressed zone is calculated according to the force equilibrium equation. according to the equation (9) obtained cracking moment results were compared with results according to the methods of standard ec2 and str for calculations were accepted the rectangular section beam with parameters: 0 2b . m= , 1 0 05d . m= , 200 s e gpa= , 50 k e gpa= , 30 c e gpa= , 2 10 s k a a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. fig. 5. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. fig. 6. the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. when the cracking moment is calculating according to the stress-strain expression (5) the resultant of the tensile concrete zone will be equal: ( ) 2 1 2 3 1 2 el h x ct el c el ct ct x f e b x b a a aε ε ε − = ⋅ ⋅ + ⋅ + ⋅ +∫ . (10) the calculation of cracking moment was performed analogically as before using the scheme presented in figure 4. the calculated cracking moment values according to the stress-strain expression (5) and expression (7) is presented in figure 7 and figure 8. the cracking moment obtained some higher when the polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0,0001656 ct ε = . in case when the expression (7) when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ct ct,lim c f e ε λ = (baikov 1991). in this case it is important right to evaluate the member lim λ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5 lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ct ct,lim c f e ε = . then the resultant of tensile concrete zone would be equal: ε x b a s ct,el ε ct ε s y xpl el x h c d m x ciε f ct,el σ σct ct,el f s ct,pl f c σ ci h f c fig. 4. strain and stress of element when compressive concrete behaviour is elastic. 1 2 el h x ct el c el ct ct c x f e b x e bε ε λ − = ⋅ ⋅ + ∫ . (8) so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct,lim ε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) ( ) ( ) ( ) ( )( ) ( ) ss c c elct ccc elctctelct elelctctelelct ccrc ae x xd xbexbe kxhkxh xx kxhbem 2 2 2 3 ,2 ,lim,, ,lim,, 3 1 3 1 24 5 3 34 3 − +++ + ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ −− + − + + − + −= ε ε ε ε εεε εεε , (9) where 1 ct,el c k ε ε = + , ct,el el c x x ε ε = , ct,lim c x h x ε ε = − . the height of the compressed zone is calculated according to the force equilibrium equation. according to the equation (9) obtained cracking moment results were compared with results according to the methods of standard ec2 and str for calculations were accepted the rectangular section beam with parameters: 0 2b . m= , 1 0 05d . m= , 200 s e gpa= , 50 k e gpa= , 30 c e gpa= , 2 10 s k a a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. fig. 5. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. fig. 6. the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. when the cracking moment is calculating according to the stress-strain expression (5) the resultant of the tensile concrete zone will be equal: ( ) 2 1 2 3 1 2 el h x ct el c el ct ct x f e b x b a a aε ε ε − = ⋅ ⋅ + ⋅ + ⋅ +∫ . (10) the calculation of cracking moment was performed analogically as before using the scheme presented in figure 4. the calculated cracking moment values according to the stress-strain expression (5) and expression (7) is presented in figure 7 and figure 8. the cracking moment obtained some higher when the polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0,0001656 ct ε = . in case when the expression (7) were used the ultimate strain value is 0 000133 ct,lim ,ε = . i.e., some lower. fig. 7. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. (mcrc,fo and mcrc,so curves when the equation (5) is applied and mcrc,f and mcrc,s curves when the equation (7) is applied). fig. 8. the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. (mcrc,fo and mcrc,so curves when the equation (5) is applied and mcrc,f and mcrc,s curves when the equation (7) is applied). analysing the influence of stress-strain relationship to the cracking moment it is important to evaluate the elastic modulus of reinforcement. calculated the cracking moment values according to the standard ec2 and str methods and equation (9) with vary elastic modulus of reinforcement is presented in figure 9. fig. 9. the relationship of the cracking moment and the elastic modulus of reinforcement. in this figure could be seen that curves obtained using different expressions of stress-strain diagram of tensile is quite similar. in these calculations were accepted such parameters.: 30 37c / , 0 2b . m= , 0 4h . m= , 1 0 05d . m= , 2 10 s a cm= . if some part of steel reinforcement to change by frp reinforcement the cracking moment will be obtained between values of element reinforced only by steel reinforcement and reinforced only by frp reinforcement. 4. conclusions 1. the application of frp reinforcement has significant influence to the cracking moment of flexural elements in compare with steel reinforcement and it influence increase when the area of frp reinforcement arises. 2. the application of different stress-strain diagrams has no significant influence to the cracking moment calculated to the flexural elements reinforced by frp and steel reinforcement. 3. in all investigated cases the calculated cracking moment values varied between values obtained by standard ec2 and str methods. this is because of rectangular ec2 method describes highest reserve. references structures, moscow: stroiizdat, 767p. en 1992-1-1:2004. eurocode 2: design of concrete structures – part 1-1: general rules and rules for buildings. 225 p. mosley w.h., bungey j.h., hulse r. 2007. reinforced concrete design to eurocode 2. 6th ed. basingstoke, palgrave macmillan. str 2.05.05:2005. design of concrete and reinforced concrete structures. 123 p. (in lithuanian). abdala h. a. evaluation of deflection in concrete members reinforced with fibre reinforced polymer (frp) bars. composite structures 56 (2002) 63-71. http://dx.doi.org/10.1016/s0263-8223(01)00188-x al-sunna r., pilakoutas k., hajirasouliha i., guadagnini m. deflection behaviour of frp reinforced concrete beams and slabs: an experimental investigation. composites part b 43 (2012) 2125-2134. http://dx.doi.org/10.1016/j.compositesb.2012.03.007 ashour a. f. flexural and shear capacities of concrete beams reinforced with gfrp bars. construction and buildng materials 20 (2006) 1005-1015. barris c., torres l., turon a., baena m., catalan a. an experimental study of the flexural behaviour of gfrp rc beams and comparison with prediction models. composite structures 91 (2009) 286-295. http://dx.doi.org/10.1016/j.compstruct.2009.05.0 05 barris c., torres l., mias c., vilanova i. .design of frp reinforced concrete beams for serviceability requirements. journal of civil engineering and management 2012 volume 18(6): 843–857. http://dx.doi.org/10.3846/13923730.2012.72093 4 were used the ultimate strain value is 0 000133 ct,lim ,ε = . i.e., some lower. fig. 7. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. (mcrc,fo and mcrc,so curves when the equation (5) is applied and mcrc,f and mcrc,s curves when the equation (7) is applied). curves when the equation (7) is applied). analysing the influence of stress-strain relationship to the cracking moment it is important to evaluate the elastic modulus of reinforcement. calculated the cracking moment values according to the standard ec2 and str methods and equation (9) with vary elastic modulus of reinforcement is presented in figure 9. fig. 9. the relationship of the cracking moment and the elastic modulus of reinforcement. in this figure could be seen that curves obtained using different expressions of stress-strain diagram of tensile is quite similar. in these calculations were accepted such parameters.: 30 37c / , 0 2b . m= , 0 4h . m= , 1 0 05d . m= , 2 10 s a cm= . if some part of steel reinforcement to change by frp reinforcement the cracking moment will be obtained between values of element reinforced only by steel reinforcement and reinforced only by frp reinforcement. 4. conclusions 1. the application of frp reinforcement has significant influence to the cracking moment of flexural elements in compare with steel reinforcement and it influence increase when the area of frp reinforcement arises. 2. the application of different stress-strain diagrams has no significant influence to the cracking moment calculated to the flexural elements reinforced by frp and steel reinforcement. 3. in all investigated cases the calculated cracking moment values varied between values obtained by standard ec2 and str methods. this is because of rectangular diagram that is described in str. also it could be state that ec2 method describes highest reserve. references 11. design to eurocode 2. 6th ed. basingstoke, palgrave macmillan. str 2.05.05:2005. design of concrete and reinforced concrete structures. 123 p. (in lithuanian). abdala h. a. evaluation of deflection in concrete members reinforced with fibre reinforced polymer (frp) bars. composite structures 56 (2002) 63-71. http://dx.doi.org/10.1016/s0263-8223(01)00188-x al-sunna r., pilakoutas k., hajirasouliha i., guadagnini m. deflection behaviour of frp reinforced concrete beams and slabs: an experimental investigation. composites part b 43 (2012) 2125-2134. http://dx.doi.org/10.1016/j.compositesb.2012.03.007 ashour a. f. flexural and shear capacities of concrete beams reinforced with gfrp bars. construction and buildng materials 20 (2006) 1005-1015. barris c., torres l., turon a., baena m., catalan a. an experimental study of the flexural behaviour of gfrp rc beams and comparison with prediction models. composite structures 91 (2009) 286-295. http://dx.doi.org/10.1016/j.compstruct.2009.05.0 05 barris c., torres l., mias c., vilanova i. .design of frp reinforced concrete beams for serviceability requirements. journal of civil engineering and management 2012 volume 18(6): 843–857. http://dx.doi.org/10.3846/13923730.2012.72093 4 “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. when the cracking moment is calculating according to the stressstrain expression (5) the resultant of the tensile concrete zone will be equal: the calculation of cracking moment was performed analogically as before using the scheme presented in figure 4. the calculated cracking moment values according to the stress-strain expression (5) and expression (7) is presented in figure 7 and figure 8. the cracking moment obtained some higher when the polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0, 0001656ctε = . in case when the expression (7) were used the ultimate strain value is 0 000133ct ,lim ,ε = . i.e., some lower. analysing the influence of stressstrain relationship to the cracking moment it is important to evaluate the elastic modulus of reinforcement. (10) when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ct ct,lim c f e ε λ = (baikov 1991). in this case it is important right to evaluate the member lim λ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5 lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ct ct,lim c f e ε = . then the resultant of tensile concrete zone would be equal: ε x b a s ct,el ε ct ε s y xpl el x h c d m x ciε f ct,el σ σct ct,el f s ct,pl f c σ ci h f c fig. 4. strain and stress of element when compressive concrete behaviour is elastic. 1 2 el h x ct el c el ct ct c x f e b x e bε ε λ − = ⋅ ⋅ + ∫ . (8) so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct,lim ε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) ( ) ( ) ( ) ( )( ) ( ) ss c c elct ccc elctctelct elelctctelelct ccrc ae x xd xbexbe kxhkxh xx kxhbem 2 2 2 3 ,2 ,lim,, ,lim,, 3 1 3 1 24 5 3 34 3 − +++ + ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ −− + − + + − + −= ε ε ε ε εεε εεε , (9) where 1 ct,el c k ε ε = + , ct,el el c x x ε ε = , ct,lim c x h x ε ε = − . the height of the compressed zone is calculated according to the force equilibrium equation. 0 2b . m= , 1 0 05d . m= , 200 s e gpa= , 50 k e = 30 c e gpa= , 2 10 s k a a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. fig. 5. constant and varies the height of cross section. fig. 6. the relationship of the cracking moment and the ( ) 2 1 2 3 1 2 el h x ct el c el x f e b xε − = ⋅ ⋅ + ∫ . (10) polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0,0001656 ct ε = . in case when the expression (7) when the cracking moment is calculating according to the elastic plastic coefficient the ultimate tensile strain is equal to ct ct,lim c f e ε λ = (baikov 1991). in this case it is important right to evaluate the member lim λ when crack opens. for tensile concrete at the short term failure case this coefficient approximately equal to ~0.5, i.e., 0 5 lim .λ = (baikov 1991). of course it is average value that could vary. but if to admit that value, the ultimate strain will be equal to 2 ct ct,lim c f e ε = . then the resultant of tensile concrete zone would be equal: ε x b a s ct,el ε ct ε s y xpl el x h c d m x ciε f ct,el σ σct ct,el f s ct,pl f c σ ci h f c fig. 4. strain and stress of element when compressive concrete behaviour is elastic. 1 2 el h x ct el c el ct ct c x f e b x e bε ε λ − = ⋅ ⋅ + ∫ . (8) so, the cracking moment will be reached then the strain of the tensile concrete will reach the ultimate strain value ct ct,lim ε ε= . according this the cracking moment could be expressed by the next equation (augonis, 2013) ( ) ( ) ( ) ( )( ) ( ) ss c c elct ccc elctctelct elelctctelelct ccrc ae x xd xbexbe kxhkxh xx kxhbem 2 2 2 3 ,2 ,lim,, ,lim,, 3 1 3 1 24 5 3 34 3 − +++ + ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ −− + − + + − + −= ε ε ε ε εεε εεε , (9) where 1 ct,el c k ε ε = + , ct,el el c x x ε ε = , ct,lim c x h x ε ε = − . the height of the compressed zone is calculated according to the force equilibrium equation. 0 2b . m= , 1 0 05d . m= , 200 s e gpa= , 50 k e = 30 c e gpa= , 2 10 s k a a cm= = , c30/37. when the reinforcement area is constant and varies the height of cross section, the relationship of cracking moment and reinforcement ratio is presented in fig. 5 where could be seen that the results obtained according to the equation (9) is between the results of ec2 and str methods. in this figure the marking: “mcrc,f” means the cracking moment of element reinforced by frp reinforcement, “mcrc,f” – reinforced by steel reinforcement, “mec2” – cracking moment calculated according to ec2 method and “mstr” – cracking moment calculated according to str method. when the cross section area is constant and varies the reinforcement area, the relationship of cracking moment and reinforcement ratio is presented in fig. 6. at this case also the results obtained according to the equation (8) is between the results of ec2 and str methods but there is higher increase of cracking moment when the amount of reinforcement arises. fig. 5. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. fig. 6. the relationship of the cracking moment and the ( ) 2 1 2 3 1 2 el h x ct el c el ct ct x f e b x b a a aε ε ε − = ⋅ ⋅ + ⋅ + ⋅ +∫ . (10) polynomial stress-strain relationship were used. this increase is evaluated by higher value of the ultimate strain that is ,1 0,0001656 ct ε = . in case when the expression (7) . fig. 5 the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section fig. 6 the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement fig. 7 the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. (mcrc,fo and mcrc,so curves when the equation (5) is applied and mcrc,f and mcrc,s curves when the equation (7) is applied) fig. 8 the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. (mcrc,fo and mcrc,so curves when the equation (5) is applied and mcrc,f and mcrc,s curves when the equation (7) is applied) 65 journal of sustainable architecture and civil engineering 2014/4/9 calculated the cracking moment values according to the standard ec2 and str methods and equation (9) with vary elastic modulus of reinforcement is presented in figure 9. in this figure could be seen that curves obtained using different expressions of stress-strain diagram of tensile is quite similar. in these calculations were accepted such parameters: 30 37c / , 0 2b . m= , 0 4h . m= , 1 0 05d . m= , 210sa cm= . were used the ultimate strain value is 0 000133 ct,lim ,ε = . i.e., some lower. fig. 7. the relationship of the cracking moment and the reinforcement coefficient when the area of the reinforcement is constant and varies the height of cross section. (mcrc,fo and mcrc,so curves when the equation (5) is applied and mcrc,f and mcrc,s curves when the equation (7) is applied). fig. 8. the relationship of the cracking moment and the reinforcement coefficient when the area of cross section is constant and varies the area of reinforcement. (mcrc,fo and mcrc,so curves when the equation (5) is applied and mcrc,f and mcrc,s the cracking moment it is important to evaluate the elastic modulus of reinforcement. calculated the cracking moment values according to the standard ec2 and str methods and equation (9) with vary elastic modulus of reinforcement is presented in figure 9. fig. 9. the relationship of the cracking moment and the elastic modulus of reinforcement. in this figure could be seen that curves obtained using different expressions of stress-strain diagram of tensile is quite similar. in these calculations were accepted such parameters.: 30 37c / , 0 2b . m= , 0 4h . m= , 1 0 05d . m= , 2 10 s a cm= . if some part of steel reinforcement to change by frp reinforcement the cracking moment will be obtained between values of element reinforced only by steel reinforcement and reinforced only by frp reinforcement. 4. conclusions 1. the application of frp reinforcement has significant influence to the cracking moment of flexural elements in compare with steel reinforcement and it influence increase when the area of frp reinforcement arises. 2. the application of different stress-strain diagrams has no significant influence to the cracking moment calculated to the flexural elements reinforced by frp and steel reinforcement. 3. in all investigated cases the calculated cracking moment values varied between values obtained by standard ec2 and str methods. this is because of rectangular diagram that is described in str. also it could be state that ec2 method describes highest reserve. references augonis a., zadlauskas s. 2013. the elastoplastic concrete strain influence on the cracking moment and deformation of rectangular reinforced concrete elements. mechanika, 19(1), 511. http://dx.doi.org/10.5755/j01.mech.19.1.3619 baikov, v.; sigalov, e. 1991. reinforced concrete structures, moscow: stroiizdat, 767p. en 1992-1-1:2004. eurocode 2: design of concrete structures – part 1-1: general rules and rules for buildings. 225 p. mosley w.h., bungey j.h., hulse r. 2007. reinforced concrete reinforced with fibre reinforced polymer (frp) bars. composite structures 56 (2002) 63-71. al-sunna r., pilakoutas k., hajirasouliha i., guadagnini m. deflection behaviour of frp reinforced concrete beams and slabs: an experimental investigation. composites part b 43 (2012) 2125-2134. reinforced with gfrp bars. construction and buildng materials 20 (2006) 1005-1015. barris c., torres l., turon a., baena m., catalan a. an experimental study of the flexural behaviour of gfrp rc beams and comparison with prediction models. composite 843–857. fig. 9 the relationship of the cracking moment and the elastic modulus of reinforcement if some part of steel reinforcement to change by frp reinforcement the cracking moment will be obtained between values of element reinforced only by steel reinforcement and reinforced only by frp reinforcement. 1 the application of frp reinforcement has significant influence to the cracking moment of flexural elements in compare with steel reinforcement and it influence increase when the area of frp reinforcement arises. 2 the application of different stress-strain diagrams has no significant influence to the cracking moment calculated to the flexural elements reinforced by frp and steel reinforcement. 3 in all investigated cases the calculated cracking moment values varied between values obtained by standard ec2 and str methods. this is because of rectangular diagram that is described in str. also it could be state that ec2 method describes highest reserve. conclusions augonis a., zadlauskas s. 2013. the elastoplastic concrete strain influence on the cracking moment and deformation of rectangular reinforced concrete elements. mechanika, 19(1), 5-11. http://dx.doi. org/10.5755/j01.mech.19.1.3619 baikov, v.; sigalov, e. 1991. reinforced concrete structures, moscow: stroiizdat, 767p. en 1992-1-1:2004. eurocode 2: design of concrete structures – part 1-1: general rules and rules for buildings. 225 p. mosley w.h., bungey j.h., hulse r. 2007. reinforced concrete design to eurocode 2. 6th ed. basingstoke, palgrave macmillan. str 2.05.05:2005. design of concrete and reinforced concrete structures. 123 p. (in lithuanian). abdala h. a. evaluation of deflection in concrete members reinforced with fibre reinforced polymer (frp) bars. composite structures 56 (2002) 63-71. http://dx.doi.org/10.1016/s0263-8223(01)00188-x al-sunna r., pilakoutas k., hajirasouliha i., guadagnini m. deflection behaviour of frp reinforced concrete beams and slabs: an experimental investigation. composites part b 43 (2012) 2125-2134. http://dx.doi.org/10.1016/j. compositesb.2012.03.007 ashour a. f. flexural and shear capacities of concrete beams reinforced with gfrp bars. construction and buildng materials 20 (2006) 1005-1015. barris c., torres l., turon a., baena m., catalan a. an experimental study of the flexural behaviour of gfrp rc beams and comparison with prediction models. composite structures 91 (2009) 286-295. http://dx.doi.org/10.1016/j.compstruct.2009.05.005 barris c., torres l., mias c., vilanova i. .design of frp reinforced concrete beams for serviceability requirements. journal of civil engineering and management 2012 volume 18(6): 843–857. http:// dx.doi.org/10.3846/13923730.2012.720934 toutanji h., deng y. deflection and crack-width prediction of concrete beams reinforced with glass frp rods. construction and buildng materials 17 (2003) 69-74. židonis, i. 2007. alternative method for the calculation of stress-strain state parameters in references journal of sustainable architecture and civil engineering 2014/4/9 66 normal sections of structural members, mechanika 67(5): 24-32. židonis, i. 2009. method for a direct calculation of stress-strain state parameters in normal rightangled sections of structural members given curvilinear stress diagrams, mechanika 77(3): 27-33. židonis, i. 2010. estimation of account the flanges in the direct calculation of stress-strain state parameters at normal sections of structural members, mechanika 81(1): 13-19. http://www.schoeck-combar.com/comb/combargfrp-reinforcement/material-138 h t t p : / / g a l e n . s u / p ro d u k t s i y a / k o m p o z i t n a y a a r m a t u ra ro c k b a r / f i z i k o m e k h a n i c h e s k i ye ispytaniya mindaugas augonis assoc. prof. kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area durability of engineering structures, strength and stability of reinforced concrete structures address studentu st. 48 lt-51367, kaunas lithuania tel. +370 37 3004731 e-mail: mindaugas.augonis@ ktu.lt robertas balevičius assoc. prof. vilnius gediminas technical university faculty of civil engineering, department of reinforced concrete and masonry structures main research area strength, stability and serviceability of reinforced concrete structures address sauletekio al. 11 lt-51367, vilnius lithuania tel. +370 37 300473 e-mail: robertas. balevicius@vgtu.lt mindaugas kasiulevičius lecturer kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area strength and durability of timber structures address studentu st. 48 lt-51367, kaunas lithuania. rėda bistrickaitė lecturer kaunas university of technology, faculty of civil engineering and architecture department of building structures main research area research of concrete and reinforced concrete innovative structures, mechanics of layerd structures, new composite materials address studentu st. 48 lt-51367, kaunas lithuania about the authors 83 journal of sustainable architecture and civil engineering 2014/3/8 jsace 3/8 journal of sustainable architecture and civil engineering vol. 3 / no. 8 / 2014 pp. 83-91 doi 10.5755/j01.sace.8.3.7144 © kaunas university of technology received 2014/05/22 accepted after revision 2014/07/05 analysis of flexural nsrc-hsrc composite members cracking behaviour and concrete properties tadas zingaila*, mindaugas augonis kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania *corresponding author: tadaszingaila@gmail.com the application of high strength concrete to reinforced concrete structures is very popular nowadays. this paper presents two main topics. in the first part of this paper, it is presented elasto-plastic properties of normal and high strength compressive concrete. it is known that actual behaviour of concrete is nonlinear. design standard en 1992-1-1 provides nonlinear stress-strain relation of compressive concrete for structural analysis. expression to calculate this relation is given in standard. in this article, there are suggested coefficients which evaluate elasto-plastic behaviour of normal and high strength compressive concrete. good correlation can be observed between stress-strain relation of compressive concrete given in standard ec2 and calculated relation using suggested elasto-plastic coefficients. in the second part of the paper, it is presented an overview of cracking moment calculations of reinforced concrete composite flexural members made from normal and high strength concrete and normal cross-section beams. these calculations were performed using existing design standard, technical construction regulation, structural building code (en 1992-1-1, str 2.05.05:2005, aci 318) and layer method. new approximate values of elasto-plastic coefficients were suggested for tension concrete. keywords: cracking moment, high strength concrete, stress-strain curve, elasto-plastic behaviour, composite beams. analysis of flexural nsrc-hsrc composite members cracking behaviour and concrete properties http://dx.doi.org/10.5755/j01.sace.8.3.7144 the applicability of concrete in structures is very popular due to various reasons: strength, durability, versatility, fire-resistance, etc. concrete is also known as ecological building material. mechanical properties of concrete are continuously studied. it is well known that the real behaviour of the concrete is nonlinear. however, the bigger part of the design standards provide cracking moment calculation methods, where the assumptions are made that the behaviour of the concrete is elastic (aci 318; ec2; mosley, bungey and hulse 2007; wight and macgregor 2008). when the calculations of cracking moment are performed, it is normal that the compression zone of the flexural member behaves elastically, but the real behaviour of the tension zone is nonlinear. the influence of tension zone nonlinearity should be taken into account when the calculations are performed. however, it can be observed that there are too little publications, books, or other sources about the stress-strain relation of tensile concrete. it is difficult to obtain direct tensile stress-strain curve, therefore limited and conflicting data of tensile concrete stress-strain relation are available (kumar et al.; shi et al., 2008). influence of tensile concrete elasto-plastic behaviour is especially important in serviceability calculations (cracking moment, deflection, curvature, etc.). introduction journal of sustainable architecture and civil engineering 2014/3/8 84 according to str and ec2, it is assumed that elastic zone of compressive concrete is approximately equal to 0.4ƒ cm . however, it is observed that for high strength concrete the zone of elastic stress-strain relation is higher than for normal strength concrete. it was determined by iravani et al. (1994) that depending on the class of high strength concrete, the value of this coefficient can reach 0.85 or even higher. great attention is given to the applicability of high strength concrete to reinforced concrete structures. in order to optimize or improve behaviour of reinforced concrete flexural members, series of analysis are performed. partial use of high strength concrete can increase stiffness of the reinforced concrete composite beams, ultimate capacity, initial cracking load and other parameters, when comparing with the beams which are made from normal strength concrete. it is observed that partial use of hsc (high strength concrete) can reduce crack width. composite beams can be also named as hybrid beams. various configurations of composite beams layers are possible. strengthening by high strength concrete can be provided in compression zone, tension zone or in compression and tension zones together. casting operation of composite nsrc-hsrc (two layers of normal and high strength concrete) beams can be performed in two cases. in the first case, both layers can be cast while the concrete is in fresh condition. this should insure full bond between different layers of the concrete. also, it is observed that transverse reinforcement can increase bond between the layers. in the other case, the second layer of new concrete can be cast when the first layer of concrete reaches its design strength (after 28 days or even later). this case can be applied for the analysis of the structural members which have to be rehabilitated or repaired. however, long time between casting phases could require additional tools to insure full bond between two layers of the concrete. application of steel fibre reinforced concrete is common in composite cross-section beams, but in this study only by steel bars reinforced concrete flexural members are analysed (kheder et al., 2010; lapko et al., 2005; sadowska-buraczewska et al., 2007). there is no united design standard which provides the calculation method for such type of the flexural members. it should be noted that it is necessary to take into account nonlinear behaviour of tension and compression concrete. therefore, this paper is intended for the analysis of the flexural nsrc-hsrc composite members cracking behaviour and concrete properties. estimation of coefficient λc,lim according to ec2 stress-strain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σ c and ε c can be calculated according to the expression: where: η = ε c /ε c1 ; ε c – compressive strain in the concrete; ε c1 – strain at peak stress; k = 1.05·e cm ·|ε c1 |/f cm ; e cm – secant modulus of elasticity of the concrete; f cm – mean value of concrete cylinder compressive strength. flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific this expression (1) is valid for 0 < |ε c | < |ε cu1 |. here ε cu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: where: λ c – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. 85 journal of sustainable architecture and civil engineering 2014/3/8 flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific flexural nsrc-hsrc composite members cracking behaviour and concrete properties. 2. estimation of coefficient λc,lim according to ec2 stressstrain relation design standard ec2 provides stress-strain relation of normal and high strength compressive concrete for nonlinear structural analysis. it includes concrete classes from c12/15 to c90/105. the relation between σc and εc can be calculated according to the expression: ; )k( k fcm c η ηησ 21 2 −+ − = (1) where: η = εc/εc1; εc – compressive strain in the concrete; εc1 – strain at peak stress; k = 1.05·ecm·|εc1|/fcm; ecm – secant modulus of elasticity of the concrete; fcm – mean value of concrete cylinder compressive strength. this expression (1) is valid for 0 < |εc1| < |εcu1|. here εcu1 is the nominal ultimate strain. when the strain in the concrete reaches the limit elastic strain of compressive concrete, the behaviour of the concrete changes from elastic to elasto-plastic, and here secant modulus of elasticity of concrete has to be recalculated to the deformation modulus of concrete. this modulus can be calculated according to the expression: ;e*e cmcc λ= (2) where: λc – coefficient which evaluates elasto-plastic deformations of compressive concrete; the expression (3), given in augonis et al. (2013) publication can be used to determine coefficient which evaluates elasto-plastic behaviour of compressive concrete. however, the limit value of this coefficient depends on the concrete class. ;k el,clim,c el,ci,c cc εε εε λ − − −=1 (3) where: kc = 1-λc,lim; λc,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; εc,i – compressive strain in the concrete; εc,el – limit elastic strain of compressive concrete; εc,lim – the limit strain of compressive concrete at the peak stress. the limit elastic strain of the compressive concrete can be calculated according to the expression: ; e fk cm cmc,el el,c ⋅ =ε (4) where: kel,c – coefficient which evaluates the limit of elastic strain of compressive concrete; the limit strain of compressive concrete at the peak stress can be calculated according to the expression: ; e f cmlim,c cm lim,c λ ε = (5) ec2 provides stress-strain relation until the nominal ultimate strain εcu1. in this research cracking moment calculations are performed. the assumption is made that λc,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stress-strain relation is analysed (until the limit strain of compressive concrete at the peak stress – εc1). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using kel,c and λc,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. fig. 1. comparison of stress-strain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients kel,c and λc. in order to calculate the limit elastic strain of the compressive concrete εc,el, which approximately corresponds the shape of ec2 stress-strain curve, coefficient kel,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of kel,c coefficients, more experimental analysis is necessary. summary of the specific where: k c = 1-λ c,lim ; λ c,lim – the limit value of coefficient which evaluates elasto-plastic deformations of compressive concrete; ε c,i – compressive strain in the concrete; ε c,el – limit elastic strain of compressive the limit elastic strain of the compressive concrete can be calculated according to the expression: the limit strain of compressive concrete at the peak stress can be calculated according to the expression: where: k el,c – coefficient which evaluates the limit of elastic strain of compressive concrete; ec2 provides stress-strain relation until the nominal ultimate strain ε cu1 . in this research cracking moment calculations are performed. the assumption is made that λ c,lim values are applied to obtain the limit strain of tensile concrete, due to this reason only the first part of stressstrain relation is analysed (until the limit strain of compressive concrete at the peak stress – ε c1 ). from fig. 1. can be observed that stress-strain relation calculated according to expression (1), which is given in ec2, has a good correlation with suggested stress-strain relation which is calculated using k el,c and λ c,lim coefficients. it also can be seen that with the increase of the concrete class, the linear part of stress-strain relation also increases. in order to calculate the limit elastic strain of the compressive concrete ε c,el , which approximately corresponds the shape of ec2 stress-strain curve, coeffifig. 1 comparison of stressstrain relation of compressive concrete calculated according to en 1992-1-1 and stress-strain relation (*) calculated using coefficients k el,c and λ c . cient k el,c is suggested for different concrete classes. the values of this coeficient using mentioned method vary from 0.01 to 0.4 for concrete classes from c20/25 to c45/55, and respectively from 0.5 to 0.65 for the concrete classes from c50/60 to c90/105. it is a tendency that for ultra-high strength concrete the value of this coefficient could be even higher. however, in the cracking moment calculations not less than 0.4 is assumed to evaluate the elastic zone of concrete. to obtain accurate values of k el,c coefficients, more experimental analysis is necessary. summary of the specific values of approximate coefficients are given in table 1 and table 2. to determine the limit strain of the compressive concrete at the peak stress, λ c,lim coefficient is concrete; ε c,lim – the limit strain of compressive concrete at the peak stress. journal of sustainable architecture and civil engineering 2014/3/8 86 used. the approximate values of this coefficient vary from 0.467 to 0.613 for concrete classes from c20/25 to c45/55, and respectively from 0.640 to 0.795 for the concrete classes from c50/60 to c90/105. the same tencency as for coeffient k el,c remains that for ultra-high strength concrete the value of this coefficient could be even higher. summary of the specific values of approximate coefficients are given in table 1 and table 2. in fig. 2. it is presented the variation of λ c coefficient, depending on the class of the concrete. the similar values of these coefficients are calculated by židonis values of approximate coefficients are given in table 1 and table 2. to determine the limit strain of the compressive concrete at the peak stress, λc,lim coefficient is used. the approximate values of this coeficient vary from 0.467 to 0.613 for concrete classes from c20/25 to c45/55, and respectively from 0.640 to 0.795 for the concrete classes from c50/60 to c90/105. the same tencency as for coeffient kel,c remains that for ultra-high strength concrete the value of this coefficient could be even higher. summary of the specific values of approximate coefficients are given in table 1 and table 2. in fig. 2. it is presented the variation of λc coefficient, depending on the class of the concrete. the similar values of these coefficients are calculated by židonis (2013). it can be observed that elasto-plastic deformations for high strength concrete occurs at much higher strain level than for normal strength concrete. when concrete behaviour is elastic, it is assumed that the deformation modulus of the concrete is equal to secant modulus of elasticity, and then the value of coefficient λc is equal to 1. fig. 2. variation of coefficient λc for different concrete classes table 1. summary of results for concrete classes from c20/25 to c45/55 characteristics c20/25 c25/30 c30/37 c35/45 c40/50 c45/55 fcm (mpa) 28 33 38 43 48 53 ecm (mpa) 30000 31000 33000 34000 35000 36000 εc1= εc,lim 0.002 0.0021 0.0022 0.00225 0.0023 0.0024 εcu1 0.0035 0.0035 0.0035 0.0035 0.0035 0.0035 kel,c 0.01 0.10 0.30 0.30 0.40 0.40 λc,lim 0.467 0.507 0.540 0.562 0.596 0.613 kc=1-λc,lim 0.533 0.493 0.460 0.438 0.404 0.387 table 2. summary of results for concrete classes from c50/60 to c90/105 characteristics c50/60 c55/67 c60/75 c70/85 c80/95 c90/105 fcm (mpa) 58 63 68 78 88 98 ecm (mpa) 37000 38000 39000 41000 42000 44000 εc1= εc,lim 0.00245 0.0025 0.0026 0.0027 0.0028 0.0028 εcu1 0.0035 0.0032 0.003 0.0028 0.0028 0.0028 kel,c 0.50 0.50 0.55 0.60 0.65 0.65 λc,lim 0.640 0.663 0.671 0.705 0.748 0.795 kc=1-λc,lim 0.360 0.337 0.329 0.295 0.252 0.205 3. calculation of cracking moment according to str, ec2, aci 318 and lm a short comparison of the different cracking moment calculation methods was carried out. calculations of the cracking moments (mcrc) were performed according to str 2.05.05:2005, ec2, aci 318 and layer method (lm). when the calculations were performed according to str, ec2 and aci 318, in all cases was assumed the transformed crosssection of the reinforced concrete beam. 3.1. technical construction regulation str 2.05.05:2005 in the calculations according to str, it is assumed to use characteristic axial tensile strength of the concrete and plastic moment of resistance of reinforced concrete member effective cross-section. cracking moment can be calculated by expression: ;wfm plctkcrc ⋅= (6) where: fctk – characteristic axial tensile strength of concrete; wpl – plastic moment of resistance of rc member effective cross-section. 3.2. design standard en 1992-1-1 design standard ec2 provides elastic stress-strain relation in the calculations of the cracking moment. here, mean value of axial tensile strength of the concrete and elastic moment of resistance are used to determine mcrc: ;wfm elctmcrc ⋅= (7) where: fctm – mean value of axial tensile strength of concrete; wel – elastic moment of resistance of rc member effective cross-section. 3.3. aci 318 structural building code aci 318 also uses elastic moment of resistance of rc member effective cross-section. however, modulus of rupture of the concrete is used instead of the axial tensile strength. mcrc can be calculated by expression: ;wfm elrcrc ⋅= (8) (2013). it can be observed that elasto-plastic deformations for high strength concrete occurs at much higher strain level than for normal strength concrete. when concrete behaviour is elastic, it is assumed that the deformation modulus of the concrete is equal to secant modulus of elasticity, and then the value of coefficient λ c is equal to 1. variation of coefficient λ c for different concrete classes table 1 summary of results for concrete classes from c20/25 to c45/55 table 2 summary of results for concrete classes from c50/60 to c90/105 characteristics c20/25 c25/30 c30/37 c35/45 c40/50 c45/55 f cm (mpa) 28 33 38 43 48 53 e cm (mpa) 30000 31000 33000 34000 35000 36000 ε c1 = ε c,lim 0.002 0.0021 0.0022 0.00225 0.0023 0.0024 ε cu1 0.0035 0.0035 0.0035 0.0035 0.0035 0.0035 k el,c 0.01 0.10 0.30 0.30 0.40 0.40 λ c,lim 0.467 0.507 0.523 0.562 0.596 0.613 k c =1-λ c,lim 0.533 0.493 0.477 0.438 0.404 0.387 characteristics c50/60 c55/67 c60/75 c70/85 c80/95 c90/105 f cm (mpa) 58 63 68 78 88 98 e cm (mpa) 37000 38000 39000 41000 42000 44000 ε c1 = ε c,lim 0.00245 0.0025 0.0026 0.0027 0.0028 0.0028 ε cu1 0.0035 0.0032 0.003 0.0028 0.0028 0.0028 k el,c 0.50 0.50 0.55 0.60 0.65 0.65 λ c,lim 0.640 0.663 0.671 0.705 0.748 0.795 k c =1-λ c,lim 0.360 0.337 0.329 0.295 0.252 0.205 fig. 2 87 journal of sustainable architecture and civil engineering 2014/3/8 values of approximate coefficients are given in table 1 and table 2. to determine the limit strain of the compressive concrete at the peak stress, λc,lim coefficient is used. the approximate values of this coeficient vary from 0.467 to 0.613 for concrete classes from c20/25 to c45/55, and respectively from 0.640 to 0.795 for the concrete classes from c50/60 to c90/105. the same tencency as for coeffient kel,c remains that for ultra-high strength concrete the value of this coefficient could be even higher. summary of the specific values of approximate coefficients are given in table 1 and table 2. in fig. 2. it is presented the variation of λc coefficient, depending on the class of the concrete. the similar values of these coefficients are calculated by židonis (2013). it can be observed that elasto-plastic deformations for high strength concrete occurs at much higher strain level than for normal strength concrete. when concrete behaviour is elastic, it is assumed that the deformation modulus of the concrete is equal to secant modulus of elasticity, and then the value of coefficient λc is equal to 1. fig. 2. variation of coefficient λc for different concrete classes table 1. summary of results for concrete classes from c20/25 to c45/55 characteristics c20/25 c25/30 c30/37 c35/45 c40/50 c45/55 fcm (mpa) 28 33 38 43 48 53 ecm (mpa) 30000 31000 33000 34000 35000 36000 εc1= εc,lim 0.002 0.0021 0.0022 0.00225 0.0023 0.0024 εcu1 0.0035 0.0035 0.0035 0.0035 0.0035 0.0035 kel,c 0.01 0.10 0.30 0.30 0.40 0.40 λc,lim 0.467 0.507 0.540 0.562 0.596 0.613 kc=1-λc,lim 0.533 0.493 0.460 0.438 0.404 0.387 table 2. summary of results for concrete classes from c50/60 to c90/105 characteristics c50/60 c55/67 c60/75 c70/85 c80/95 c90/105 fcm (mpa) 58 63 68 78 88 98 ecm (mpa) 37000 38000 39000 41000 42000 44000 εc1= εc,lim 0.00245 0.0025 0.0026 0.0027 0.0028 0.0028 εcu1 0.0035 0.0032 0.003 0.0028 0.0028 0.0028 kel,c 0.50 0.50 0.55 0.60 0.65 0.65 λc,lim 0.640 0.663 0.671 0.705 0.748 0.795 kc=1-λc,lim 0.360 0.337 0.329 0.295 0.252 0.205 3. calculation of cracking moment according to str, ec2, aci 318 and lm a short comparison of the different cracking moment calculation methods was carried out. calculations of the cracking moments (mcrc) were performed according to str 2.05.05:2005, ec2, aci 318 and layer method (lm). when the calculations were performed according to str, ec2 and aci 318, in all cases was assumed the transformed crosssection of the reinforced concrete beam. 3.1. technical construction regulation str 2.05.05:2005 in the calculations according to str, it is assumed to use characteristic axial tensile strength of the concrete and plastic moment of resistance of reinforced concrete member effective cross-section. cracking moment can be calculated by expression: ;wfm plctkcrc ⋅= (6) where: fctk – characteristic axial tensile strength of concrete; wpl – plastic moment of resistance of rc member effective cross-section. 3.2. design standard en 1992-1-1 design standard ec2 provides elastic stress-strain relation in the calculations of the cracking moment. here, mean value of axial tensile strength of the concrete and elastic moment of resistance are used to determine mcrc: ;wfm elctmcrc ⋅= (7) where: fctm – mean value of axial tensile strength of concrete; wel – elastic moment of resistance of rc member effective cross-section. 3.3. aci 318 structural building code aci 318 also uses elastic moment of resistance of rc member effective cross-section. however, modulus of rupture of the concrete is used instead of the axial tensile strength. mcrc can be calculated by expression: ;wfm elrcrc ⋅= (8) values of approximate coefficients are given in table 1 and table 2. to determine the limit strain of the compressive concrete at the peak stress, λc,lim coefficient is used. the approximate values of this coeficient vary from 0.467 to 0.613 for concrete classes from c20/25 to c45/55, and respectively from 0.640 to 0.795 for the concrete classes from c50/60 to c90/105. the same tencency as for coeffient kel,c remains that for ultra-high strength concrete the value of this coefficient could be even higher. summary of the specific values of approximate coefficients are given in table 1 and table 2. in fig. 2. it is presented the variation of λc coefficient, depending on the class of the concrete. the similar values of these coefficients are calculated by židonis (2013). it can be observed that elasto-plastic deformations for high strength concrete occurs at much higher strain level than for normal strength concrete. when concrete behaviour is elastic, it is assumed that the deformation modulus of the concrete is equal to secant modulus of elasticity, and then the value of coefficient λc is equal to 1. fig. 2. variation of coefficient λc for different concrete classes table 1. summary of results for concrete classes from c20/25 to c45/55 characteristics c20/25 c25/30 c30/37 c35/45 c40/50 c45/55 fcm (mpa) 28 33 38 43 48 53 ecm (mpa) 30000 31000 33000 34000 35000 36000 εc1= εc,lim 0.002 0.0021 0.0022 0.00225 0.0023 0.0024 εcu1 0.0035 0.0035 0.0035 0.0035 0.0035 0.0035 kel,c 0.01 0.10 0.30 0.30 0.40 0.40 λc,lim 0.467 0.507 0.540 0.562 0.596 0.613 kc=1-λc,lim 0.533 0.493 0.460 0.438 0.404 0.387 table 2. summary of results for concrete classes from c50/60 to c90/105 characteristics c50/60 c55/67 c60/75 c70/85 c80/95 c90/105 fcm (mpa) 58 63 68 78 88 98 ecm (mpa) 37000 38000 39000 41000 42000 44000 εc1= εc,lim 0.00245 0.0025 0.0026 0.0027 0.0028 0.0028 εcu1 0.0035 0.0032 0.003 0.0028 0.0028 0.0028 kel,c 0.50 0.50 0.55 0.60 0.65 0.65 λc,lim 0.640 0.663 0.671 0.705 0.748 0.795 kc=1-λc,lim 0.360 0.337 0.329 0.295 0.252 0.205 3. calculation of cracking moment according to str, ec2, aci 318 and lm a short comparison of the different cracking moment calculation methods was carried out. calculations of the cracking moments (mcrc) were performed according to str 2.05.05:2005, ec2, aci 318 and layer method (lm). when the calculations were performed according to str, ec2 and aci 318, in all cases was assumed the transformed crosssection of the reinforced concrete beam. 3.1. technical construction regulation str 2.05.05:2005 in the calculations according to str, it is assumed to use characteristic axial tensile strength of the concrete and plastic moment of resistance of reinforced concrete member effective cross-section. cracking moment can be calculated by expression: ;wfm plctkcrc ⋅= (6) where: fctk – characteristic axial tensile strength of concrete; wpl – plastic moment of resistance of rc member effective cross-section. 3.2. design standard en 1992-1-1 design standard ec2 provides elastic stress-strain relation in the calculations of the cracking moment. here, mean value of axial tensile strength of the concrete and elastic moment of resistance are used to determine mcrc: ;wfm elctmcrc ⋅= (7) where: fctm – mean value of axial tensile strength of concrete; wel – elastic moment of resistance of rc member effective cross-section. 3.3. aci 318 structural building code aci 318 also uses elastic moment of resistance of rc member effective cross-section. however, modulus of rupture of the concrete is used instead of the axial tensile strength. mcrc can be calculated by expression: ;wfm elrcrc ⋅= (8) values of approximate coefficients are given in table 1 and table 2. to determine the limit strain of the compressive concrete at the peak stress, λc,lim coefficient is used. the approximate values of this coeficient vary from 0.467 to 0.613 for concrete classes from c20/25 to c45/55, and respectively from 0.640 to 0.795 for the concrete classes from c50/60 to c90/105. the same tencency as for coeffient kel,c remains that for ultra-high strength concrete the value of this coefficient could be even higher. summary of the specific values of approximate coefficients are given in table 1 and table 2. in fig. 2. it is presented the variation of λc coefficient, depending on the class of the concrete. the similar values of these coefficients are calculated by židonis (2013). it can be observed that elasto-plastic deformations for high strength concrete occurs at much higher strain level than for normal strength concrete. when concrete behaviour is elastic, it is assumed that the deformation modulus of the concrete is equal to secant modulus of elasticity, and then the value of coefficient λc is equal to 1. fig. 2. variation of coefficient λc for different concrete classes table 1. summary of results for concrete classes from c20/25 to c45/55 characteristics c20/25 c25/30 c30/37 c35/45 c40/50 c45/55 fcm (mpa) 28 33 38 43 48 53 ecm (mpa) 30000 31000 33000 34000 35000 36000 εc1= εc,lim 0.002 0.0021 0.0022 0.00225 0.0023 0.0024 εcu1 0.0035 0.0035 0.0035 0.0035 0.0035 0.0035 kel,c 0.01 0.10 0.30 0.30 0.40 0.40 λc,lim 0.467 0.507 0.540 0.562 0.596 0.613 kc=1-λc,lim 0.533 0.493 0.460 0.438 0.404 0.387 table 2. summary of results for concrete classes from c50/60 to c90/105 characteristics c50/60 c55/67 c60/75 c70/85 c80/95 c90/105 fcm (mpa) 58 63 68 78 88 98 ecm (mpa) 37000 38000 39000 41000 42000 44000 εc1= εc,lim 0.00245 0.0025 0.0026 0.0027 0.0028 0.0028 εcu1 0.0035 0.0032 0.003 0.0028 0.0028 0.0028 kel,c 0.50 0.50 0.55 0.60 0.65 0.65 λc,lim 0.640 0.663 0.671 0.705 0.748 0.795 kc=1-λc,lim 0.360 0.337 0.329 0.295 0.252 0.205 3. calculation of cracking moment according to str, ec2, aci 318 and lm a short comparison of the different cracking moment calculation methods was carried out. calculations of the cracking moments (mcrc) were performed according to str 2.05.05:2005, ec2, aci 318 and layer method (lm). when the calculations were performed according to str, ec2 and aci 318, in all cases was assumed the transformed crosssection of the reinforced concrete beam. 3.1. technical construction regulation str 2.05.05:2005 in the calculations according to str, it is assumed to use characteristic axial tensile strength of the concrete and plastic moment of resistance of reinforced concrete member effective cross-section. cracking moment can be calculated by expression: ;wfm plctkcrc ⋅= (6) where: fctk – characteristic axial tensile strength of concrete; wpl – plastic moment of resistance of rc member effective cross-section. 3.2. design standard en 1992-1-1 design standard ec2 provides elastic stress-strain relation in the calculations of the cracking moment. here, mean value of axial tensile strength of the concrete and elastic moment of resistance are used to determine mcrc: ;wfm elctmcrc ⋅= (7) where: fctm – mean value of axial tensile strength of concrete; wel – elastic moment of resistance of rc member effective cross-section. 3.3. aci 318 structural building code aci 318 also uses elastic moment of resistance of rc member effective cross-section. however, modulus of rupture of the concrete is used instead of the axial tensile strength. mcrc can be calculated by expression: ;wfm elrcrc ⋅= (8) values of approximate coefficients are given in table 1 and table 2. to determine the limit strain of the compressive concrete at the peak stress, λc,lim coefficient is used. the approximate values of this coeficient vary from 0.467 to 0.613 for concrete classes from c20/25 to c45/55, and respectively from 0.640 to 0.795 for the concrete classes from c50/60 to c90/105. the same tencency as for coeffient kel,c remains that for ultra-high strength concrete the value of this coefficient could be even higher. summary of the specific values of approximate coefficients are given in table 1 and table 2. in fig. 2. it is presented the variation of λc coefficient, depending on the class of the concrete. the similar values of these coefficients are calculated by židonis (2013). it can be observed that elasto-plastic deformations for high strength concrete occurs at much higher strain level than for normal strength concrete. when concrete behaviour is elastic, it is assumed that the deformation modulus of the concrete is equal to secant modulus of elasticity, and then the value of coefficient λc is equal to 1. fig. 2. variation of coefficient λc for different concrete classes table 1. summary of results for concrete classes from c20/25 to c45/55 characteristics c20/25 c25/30 c30/37 c35/45 c40/50 c45/55 fcm (mpa) 28 33 38 43 48 53 ecm (mpa) 30000 31000 33000 34000 35000 36000 εc1= εc,lim 0.002 0.0021 0.0022 0.00225 0.0023 0.0024 εcu1 0.0035 0.0035 0.0035 0.0035 0.0035 0.0035 kel,c 0.01 0.10 0.30 0.30 0.40 0.40 λc,lim 0.467 0.507 0.540 0.562 0.596 0.613 kc=1-λc,lim 0.533 0.493 0.460 0.438 0.404 0.387 table 2. summary of results for concrete classes from c50/60 to c90/105 characteristics c50/60 c55/67 c60/75 c70/85 c80/95 c90/105 fcm (mpa) 58 63 68 78 88 98 ecm (mpa) 37000 38000 39000 41000 42000 44000 εc1= εc,lim 0.00245 0.0025 0.0026 0.0027 0.0028 0.0028 εcu1 0.0035 0.0032 0.003 0.0028 0.0028 0.0028 kel,c 0.50 0.50 0.55 0.60 0.65 0.65 λc,lim 0.640 0.663 0.671 0.705 0.748 0.795 kc=1-λc,lim 0.360 0.337 0.329 0.295 0.252 0.205 3. calculation of cracking moment according to str, ec2, aci 318 and lm a short comparison of the different cracking moment calculation methods was carried out. calculations of the cracking moments (mcrc) were performed according to str 2.05.05:2005, ec2, aci 318 and layer method (lm). when the calculations were performed according to str, ec2 and aci 318, in all cases was assumed the transformed crosssection of the reinforced concrete beam. 3.1. technical construction regulation str 2.05.05:2005 in the calculations according to str, it is assumed to use characteristic axial tensile strength of the concrete and plastic moment of resistance of reinforced concrete member effective cross-section. cracking moment can be calculated by expression: ;wfm plctkcrc ⋅= (6) where: fctk – characteristic axial tensile strength of concrete; wpl – plastic moment of resistance of rc member effective cross-section. 3.2. design standard en 1992-1-1 design standard ec2 provides elastic stress-strain relation in the calculations of the cracking moment. here, mean value of axial tensile strength of the concrete and elastic moment of resistance are used to determine mcrc: ;wfm elctmcrc ⋅= (7) where: fctm – mean value of axial tensile strength of concrete; wel – elastic moment of resistance of rc member effective cross-section. 3.3. aci 318 structural building code aci 318 also uses elastic moment of resistance of rc member effective cross-section. however, modulus of rupture of the concrete is used instead of the axial tensile strength. mcrc can be calculated by expression: ;wfm elrcrc ⋅= (8) values of approximate coefficients are given in table 1 and table 2. to determine the limit strain of the compressive concrete at the peak stress, λc,lim coefficient is used. the approximate values of this coeficient vary from 0.467 to 0.613 for concrete classes from c20/25 to c45/55, and respectively from 0.640 to 0.795 for the concrete classes from c50/60 to c90/105. the same tencency as for coeffient kel,c remains that for ultra-high strength concrete the value of this coefficient could be even higher. summary of the specific values of approximate coefficients are given in table 1 and table 2. in fig. 2. it is presented the variation of λc coefficient, depending on the class of the concrete. the similar values of these coefficients are calculated by židonis (2013). it can be observed that elasto-plastic deformations for high strength concrete occurs at much higher strain level than for normal strength concrete. when concrete behaviour is elastic, it is assumed that the deformation modulus of the concrete is equal to secant modulus of elasticity, and then the value of coefficient λc is equal to 1. fig. 2. variation of coefficient λc for different concrete classes table 1. summary of results for concrete classes from c20/25 to c45/55 characteristics c20/25 c25/30 c30/37 c35/45 c40/50 c45/55 fcm (mpa) 28 33 38 43 48 53 ecm (mpa) 30000 31000 33000 34000 35000 36000 εc1= εc,lim 0.002 0.0021 0.0022 0.00225 0.0023 0.0024 εcu1 0.0035 0.0035 0.0035 0.0035 0.0035 0.0035 kel,c 0.01 0.10 0.30 0.30 0.40 0.40 λc,lim 0.467 0.507 0.540 0.562 0.596 0.613 kc=1-λc,lim 0.533 0.493 0.460 0.438 0.404 0.387 table 2. summary of results for concrete classes from c50/60 to c90/105 characteristics c50/60 c55/67 c60/75 c70/85 c80/95 c90/105 fcm (mpa) 58 63 68 78 88 98 ecm (mpa) 37000 38000 39000 41000 42000 44000 εc1= εc,lim 0.00245 0.0025 0.0026 0.0027 0.0028 0.0028 εcu1 0.0035 0.0032 0.003 0.0028 0.0028 0.0028 kel,c 0.50 0.50 0.55 0.60 0.65 0.65 λc,lim 0.640 0.663 0.671 0.705 0.748 0.795 kc=1-λc,lim 0.360 0.337 0.329 0.295 0.252 0.205 3. calculation of cracking moment according to str, ec2, aci 318 and lm a short comparison of the different cracking moment calculation methods was carried out. calculations of the cracking moments (mcrc) were performed according to str 2.05.05:2005, ec2, aci 318 and layer method (lm). when the calculations were performed according to str, ec2 and aci 318, in all cases was assumed the transformed crosssection of the reinforced concrete beam. 3.1. technical construction regulation str 2.05.05:2005 in the calculations according to str, it is assumed to use characteristic axial tensile strength of the concrete and plastic moment of resistance of reinforced concrete member effective cross-section. cracking moment can be calculated by expression: ;wfm plctkcrc ⋅= (6) where: fctk – characteristic axial tensile strength of concrete; wpl – plastic moment of resistance of rc member effective cross-section. 3.2. design standard en 1992-1-1 design standard ec2 provides elastic stress-strain relation in the calculations of the cracking moment. here, mean value of axial tensile strength of the concrete and elastic moment of resistance are used to determine mcrc: ;wfm elctmcrc ⋅= (7) where: fctm – mean value of axial tensile strength of concrete; wel – elastic moment of resistance of rc member effective cross-section. 3.3. aci 318 structural building code aci 318 also uses elastic moment of resistance of rc member effective cross-section. however, modulus of rupture of the concrete is used instead of the axial tensile strength. mcrc can be calculated by expression: ;wfm elrcrc ⋅= (8) values of approximate coefficients are given in table 1 and table 2. to determine the limit strain of the compressive concrete at the peak stress, λc,lim coefficient is used. the approximate values of this coeficient vary from 0.467 to 0.613 for concrete classes from c20/25 to c45/55, and respectively from 0.640 to 0.795 for the concrete classes from c50/60 to c90/105. the same tencency as for coeffient kel,c remains that for ultra-high strength concrete the value of this coefficient could be even higher. summary of the specific values of approximate coefficients are given in table 1 and table 2. in fig. 2. it is presented the variation of λc coefficient, depending on the class of the concrete. the similar values of these coefficients are calculated by židonis (2013). it can be observed that elasto-plastic deformations for high strength concrete occurs at much higher strain level than for normal strength concrete. when concrete behaviour is elastic, it is assumed that the deformation modulus of the concrete is equal to secant modulus of elasticity, and then the value of coefficient λc is equal to 1. fig. 2. variation of coefficient λc for different concrete classes table 1. summary of results for concrete classes from c20/25 to c45/55 characteristics c20/25 c25/30 c30/37 c35/45 c40/50 c45/55 fcm (mpa) 28 33 38 43 48 53 ecm (mpa) 30000 31000 33000 34000 35000 36000 εc1= εc,lim 0.002 0.0021 0.0022 0.00225 0.0023 0.0024 εcu1 0.0035 0.0035 0.0035 0.0035 0.0035 0.0035 kel,c 0.01 0.10 0.30 0.30 0.40 0.40 λc,lim 0.467 0.507 0.540 0.562 0.596 0.613 kc=1-λc,lim 0.533 0.493 0.460 0.438 0.404 0.387 table 2. summary of results for concrete classes from c50/60 to c90/105 characteristics c50/60 c55/67 c60/75 c70/85 c80/95 c90/105 fcm (mpa) 58 63 68 78 88 98 ecm (mpa) 37000 38000 39000 41000 42000 44000 εc1= εc,lim 0.00245 0.0025 0.0026 0.0027 0.0028 0.0028 εcu1 0.0035 0.0032 0.003 0.0028 0.0028 0.0028 kel,c 0.50 0.50 0.55 0.60 0.65 0.65 λc,lim 0.640 0.663 0.671 0.705 0.748 0.795 kc=1-λc,lim 0.360 0.337 0.329 0.295 0.252 0.205 3. calculation of cracking moment according to str, ec2, aci 318 and lm a short comparison of the different cracking moment calculation methods was carried out. calculations of the cracking moments (mcrc) were performed according to str 2.05.05:2005, ec2, aci 318 and layer method (lm). when the calculations were performed according to str, ec2 and aci 318, in all cases was assumed the transformed crosssection of the reinforced concrete beam. 3.1. technical construction regulation str 2.05.05:2005 in the calculations according to str, it is assumed to use characteristic axial tensile strength of the concrete and plastic moment of resistance of reinforced concrete member effective cross-section. cracking moment can be calculated by expression: ;wfm plctkcrc ⋅= (6) where: fctk – characteristic axial tensile strength of concrete; wpl – plastic moment of resistance of rc member effective cross-section. 3.2. design standard en 1992-1-1 design standard ec2 provides elastic stress-strain relation in the calculations of the cracking moment. here, mean value of axial tensile strength of the concrete and elastic moment of resistance are used to determine mcrc: ;wfm elctmcrc ⋅= (7) where: fctm – mean value of axial tensile strength of concrete; wel – elastic moment of resistance of rc member effective cross-section. 3.3. aci 318 structural building code aci 318 also uses elastic moment of resistance of rc member effective cross-section. however, modulus of rupture of the concrete is used instead of the axial tensile strength. mcrc can be calculated by expression: ;wfm elrcrc ⋅= (8) calculation of cracking moment according to str, ec2, aci 318 and lm a short comparison of the different cracking moment calculation methods was carried out. calculations of the cracking moments (m crc ) were performed according to str 2.05.05:2005, ec2, aci 318 and layer method (lm). when the calculations were performed according to str, ec2 and aci 318, in all cases was assumed the transformed cross-section of the reinforced concrete beam. technical construction regulation str 2.05.05:2005 in the calculations according to str, it is assumed to use characteristic axial tensile strength of the concrete and plastic moment of resistance of reinforced concrete member effective cross-section. cracking moment can be calculated by expression: where: f ctk – characteristic axial tensile strength of concrete; w pl – plastic moment of resistance of rc member effective cross-section. design standard en 1992-1-1 design standard ec2 provides elastic stress-strain relation in the calculations of the cracking moment. here, mean value of axial tensile strength of the concrete and elastic moment of resistance are used to determine m crc : where: f ctm – mean value of axial tensile strength of concrete; w el – elastic moment of resistance of rc member effective cross-section. aci 318 structural building code aci 318 also uses elastic moment of resistance of rc member effective cross-section. however, modulus of rupture of the concrete is used instead of the axial tensile strength. m crc can be calculated by expression: where: f r – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f ’ – specified compressive strength of concrete. 3.4. layer method layer method was used to calculate the cracking force and moment equations of equilibrium: ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: ( ) ( ) ; f e f el,ctct ci,ctlim,ct el,ctct el,ctlim,ct ct ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − ⋅−− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − −− + = σ ελ σ σλ λ 1 1 1 1 (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength concrete (90(h2)/185(h1)×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. approximately 20 mpa normal strength concrete and about 70 mpa high strength concrete was used in kheder et al. (2010) experiment. the beams were double reinforced. four types of reinforcement were used for beams. • tension reinforcement: 2ø16, 3ø16 (as1 – 34 mm), 2ø25, 3ø25 (as1 – 38.5 mm), (es1 – 205000 mpa), • compression reinforcement: 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete c c where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f ’ – specified compressive strength of concrete. 3.4. layer method layer method was used to calculate the cracking moment evaluating that stress-strain relation of tension : ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: ( ) ( ) ; f e f el,ctct ci,ctlim,ct el,ctct el,ctlim,ct ct ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − ⋅−− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − −− + = σ ελ σ σλ λ 1 1 1 1 (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength concrete (90(h2)/185(h1)×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. approximately 20 mpa normal strength concrete and about 70 mpa high strength concrete was used in kheder et al. (2010) experiment. the beams were double reinforced. four types of , 3ø16 (as1 – 34 mm), ( , (es1 – 205000 mpa), : 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete c c where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f ’ – specified compressive strength of concrete. 3.4. layer method layer method was used to calculate the cracking moment evaluating that stress-strain relation of tension concrete is elasto-plastic. the cross-section of the beam was calculations lm can be expressed from : ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: ( ) ( ) ; f e f el,ctct ci,ctlim,ct el,ctct el,ctlim,ct ct ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − ⋅−− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − −− + = σ ελ σ σλ λ 1 1 1 1 (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength concrete (90(h2)/185(h1)×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. approximately 20 mpa normal strength concrete and about 70 mpa high strength concrete was used in kheder et al. (2010) experiment. the beams were double reinforced. four types of reinforcement were used for beams. • tension reinforcement: 2ø16, 3ø16 (as1 – 34 mm), 2ø25, 3ø25 (as1 – 38.5 mm), (es1 – 205000 mpa), • compression reinforcement: 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete c c where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f ’ – specified compressive strength of concrete. 3.4. layer method layer method was used to calculate the cracking moment evaluating that stress-strain relation of tension ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: ( ) ( ) ; f e f el,ctct ci,ctlim,ct el,ctct el,ctlim,ct ct ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − ⋅−− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − −− + = σ ελ σ σλ λ 1 1 1 1 (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength concrete (90(h2)/185(h1)×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. approximately 20 mpa normal strength concrete and about 70 mpa high strength concrete was used in kheder et al. (2010) experiment. , 3ø16 (as1 – 34 mm), (as1 – 38.5 mm), (es1 – 205000 mpa), : 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete c c where: where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f ’ – specified compressive strength of concrete. divided into small layers. strain, stress, and other characteristics were calculated in each layer. calculations are performed by iterations. lm can be expressed from force and moment equations of equilibrium: ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: ( ) ( ) ; f e f el,ctct ci,ctlim,ct el,ctct el,ctlim,ct ct ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − ⋅−− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − −− + = σ ελ σ σλ λ 1 1 1 1 (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength concrete (90(h2)/185(h1)×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. et al. • tension reinforcement: 2ø16, 3ø16 (as1 – 34 mm), 2ø25, 3ø25 (as1 – 38.5 mm), (es1 – 205000 mpa), • compression reinforcement: 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete c c – specified compressive strength of concrete. layer method layer method (augonis et al. 2013) was used to calculate the cracking moment evaluating that stress-strain relation of tension concrete is elasto-plastic. the cross-section of the beam was divided into small layers. strain, stress, and other characteristics were calculated in each layer. calculations are performed by iterations. lm can be expressed from force and moment equations of equilibrium: journal of sustainable architecture and civil engineering 2014/3/8 88 where: e ci – deformation modulus of concrete of i layer; a ci – area of concrete of i layer, ε ci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); z ci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); e s1 , e s2 – design value of modulus of elasticity of reinforcing steel; ε s1 , ε s2 – strain in tension (“-”) and compression (“+”) reinforcement; z s1 , z s2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stress-strain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λ ct can be calculated according to the experssion: where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f’ – specified compressive strength of concrete. 3.4. layer method layer method was used to calculate the cracking moment evaluating that stress-strain relation of tension concrete is elasto-plastic. the cross-section of the beam was divided into small layers. strain, stress, and other characteristics were calculated in each layer. calculations are performed by iterations. lm can be expressed from force and moment equations of equilibrium: ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength concrete (90(h2)/185(h1)×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. approximately 20 mpa normal strength concrete and about 70 mpa high strength concrete was used in kheder et al. (2010) experiment. the beams were double reinforced. four types of reinforcement were used for beams. • tension reinforcement: 2ø16, 3ø16 (as1 – 34 mm), 2ø25, 3ø25 (as1 – 38.5 mm), (es1 – 205000 mpa), • compression reinforcement: 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f’ – specified compressive strength of concrete. 3.4. layer method layer method was used to calculate the cracking moment evaluating that stress-strain relation of tension concrete is elasto-plastic. the cross-section of the beam was divided into small layers. strain, stress, and other characteristics were calculated in each layer. calculations are performed by iterations. lm can be expressed from force and moment equations of equilibrium: ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: ( ) ( ) ; f e f el,ctctk ci,ctlim,ct el,ctctk el,ctlim,ct ct ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − ⋅−− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − −− + = σ ελ σ σλ λ 1 1 1 1 (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength concrete (90(h2)/185(h1)×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. approximately 20 mpa normal strength concrete and about 70 mpa high strength concrete was used in kheder et al. (2010) experiment. the beams were double reinforced. four types of reinforcement were used for beams. • tension reinforcement: 2ø16, 3ø16 (as1 – 34 mm), 2ø25, 3ø25 (as1 – 38.5 mm), (es1 – 205000 mpa), • compression reinforcement: 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f’ – specified compressive strength of concrete. 3.4. layer method layer method was used to calculate the cracking moment evaluating that stress-strain relation of tension concrete is elasto-plastic. the cross-section of the beam was divided into small layers. strain, stress, and other characteristics were calculated in each layer. calculations are performed by iterations. lm can be expressed from force and moment equations of equilibrium: ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: ( ) ( ) ; f e f el,ctctk ci,ctlim,ct el,ctctk el,ctlim,ct ct ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − ⋅−− + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − −− + = σ ελ σ σλ λ 1 1 1 1 (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength b)). by used in kheder et al. reinforcement were used for beams. • tension reinforcement: 2ø16, 3ø16 (as1 – 34 mm), 2ø25, 3ø25 (as1 – 38.5 mm), (es1 – 205000 mpa), • compression reinforcement: 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete where: fr – modulus of rupture of concrete; modulus of rupture of concrete can be expressed: ;'f.fr ⋅= 620 (9) where: f’ – specified compressive strength of concrete. 3.4. layer method layer method was used to calculate the cracking moment evaluating that stress-strain relation of tension concrete is elasto-plastic. the cross-section of the beam was divided into small layers. strain, stress, and other characteristics were calculated in each layer. calculations are performed by iterations. lm can be expressed from force and moment equations of equilibrium: ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =++ =++ ∑ ∑ = = mzaezaezae aeaeae n i sssssssscicicici n i sssssscicici 1 22221111 1 222111 0 εεε εεε (10) where: eci – deformation modulus of concrete of i layer; aci – area of concrete of i layer, εci – strain of concrete in i layer (“+” in compression zone, “-” in tension zone); zci – arm of force acting in concrete i layer (distance from the center of the most tension layer to the center of i layer); es1, es2 – design value of modulus of elasticity of reinforcing steel; εs1, εs2 – strain in tension (“-”) and compression (“+”) reinforcement; zs1, zs2 – arm of force acting in reinforcement (distance from the center of the most tension layer to the center of reinforcement); m – external bending moment. expression (3) is given to calculate coefficient which evaluates elasto-plastic behaviour of compressive concrete. good correlation was obtained between calculated stressstrain curve and ec2 stress-strain relation. however, to evaluate elasto-plastic behaviour of tension concrete in cracking moment calculations, more accurate expression was suggested. coefficients λct can be calculated according to the experssion: ( ( f f ,ctk ,ct ct ⎜ ⎜ ⎝ ⎛ − + ⎜ ⎜ ⎝ ⎛ − + = λ λ λ 1 1 1 1 (11) where: λct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, fctk – characteristic axial tensile strength of concrete; σct,el – the limit elastic stress of tensile concrete; εct,i – strain of tensile concrete in i layer; ec – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of mcrc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. three different types of the beams were used: • normal strength concrete beams (275(h)×175(b)); • high strength concrete beams (275(h)×175(b)); • composite beams from normal and high strength concrete (90(h2)/185(h1)×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. approximately 20 mpa normal strength concrete and about 70 mpa high strength concrete was used in kheder et al. (2010) experiment. the beams were double reinforced. four types of reinforcement were used for beams. • tension reinforcement: 2ø16, 3ø16 (as1 – 34 mm), 2ø25, 3ø25 (as1 – 38.5 mm), (es1 – 205000 mpa), • compression reinforcement: 2ø6 (not given in publication, so assumed that as2 – 34 and 38.5 mm), (es2 – 210000 mpa). fig. 3. parameters of beams cross-sections cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3. table 3. properties of tested concrete (kheder et al. 2010) specimen no. fck (mpa) fctk (mpa) ec (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.728/– 24880/– nsrc/603 23/– 1.698/– 22540/– nsrc/982 21/– 1.598/– 21530/– nsrc/1473 22/– 1.649/– 22000/– hsrc/402 –/65.4 –/3.148 –/38000 hsrc/603 –/71.7 –/3.256 –/39800 hsrc/982 –/74.9 –/3.308 –/40660 hsrc/1473 –/68.8 –/3.207 –/39000 nhsrc/402 22/71.4 1.649/3.251 23950/41870 nhsrc/603 22/71.1 1.649/3.246 23700/41520 nhsrc/982 21.2/68.3 1.609/3.198 22460/39850 nhsrc/1473 22.3/73.7 1.664/3.288 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); fctk – characteristic axial tensile strength of concrete calculated according to ec2; fck – characteristic axial compressive strength of concrete; ec – modulus of elasticity of concrete where: λ ct,lim – the limit value of coefficient which evaluates elasto-plastic deformations of tensile concrete, f ctk – characteristic axial tensile strength of concrete; σ ct,el – the limit elastic stress of tensile concrete; ε ct,i – strain of tensile concrete in i layer; e c – modulus of elasticity of concrete. the parameters of the beams cross-sections are given below. such parameters were used in order to compare calculated values of m crc with experimental values. experimental values of the cracking moments were calculated according to the information (initial cracking load, loading scheme, etc.) given in kheder et al. (2010) publication. therefore, some data were used from these scientists’ experimental research. cross-sections of the beams are given in fig. 3. fig. 3 parameters of beams cross-sections three different types of the beams were used: _ normal strength concrete beams (275(h)×175(b)); _ high strength concrete beams (275(h)×175(b)); _ composite beams from normal and high strength concrete (90(h 2 )/185(h 1 )×175(b)). normal strength concrete beams were strengthened by high strength concrete layer in compression zone. approximately 20 mpa normal strength concrete and about 70 mpa high strength concrete was used in kheder et al. (2010) experiment. the beams were double reinforced. four types of reinforcement were used for beams. _ tension reinforcement: 2ø16, 3ø16 (a s1 – 34 mm), 2ø25, 3ø25 (a s1 – 38.5 mm), (e s1 – 205000 mpa), _ compression reinforcement: 2ø6 (not given in publication, so assumed that a s2 – 34 and 38.5 mm), (e s2 – 210000 mpa). cylindrical compressive strength and modulus of elasticity of tested beams were used from kheder et al. (2010) experiment. tensile strength of the concrete was calculated according to ec2 expressions and it is presented in table 3.     ; f e f el,ctct ci,ctlim,ct el,ctct el,ctlim,ct ct                             1 1 1 1 89 journal of sustainable architecture and civil engineering 2014/3/8 table 3 properties of tested concrete (kheder et al. 2010) table 4 summary of experimental and calculated results (mean values of concrete properties were used in all calculations) specimen no. f cm (mpa) f ctm (mpa) e c (mpa) nsc/hsc nsc/hsc nsc/hsc nsrc/402 23.6/– 1.873/– 24880/– nsrc/603 23/– 1.825/– 22540/– nsrc/982 21/– 1.659/– 21530/– nsrc/1473 22/– 1.743/– 22000/– hsrc/402 –/65.4 –/4.283 –/38000 hsrc/603 –/71.7 –/4.453 –/39800 hsrc/982 –/74.9 –/4.534 –/40660 hsrc/1473 –/68.8 –/4.376 –/39000 nhsrc/402 22/71.4 1.743/4.445 23950/41870 nhsrc/603 22/71.1 1.743/4.437 23700/41520 nhsrc/982 21.2/68.3 1.676/4.363 22460/39850 nhsrc/1473 22.3/73.7 1.767/4.504 24210/42530 where: xxxx/y: xxxx – strength of concrete (n – normal, h – high, nh – composite beam from normal and high strength of concrete); r – reinforced; y – area of tension reinforcement (mm2); e c – modulus of elasticity of concrete. results analysis of the cracking moment calculations was performed according to str, ec2, aci 318 and lm. all results were compared with the experimental research results (kheder et al. 2010). due to this reason, the mean values of concrete properties were used in the calculation methods given in str, ec2 and aci 318. when the calculations were performed according to the available regulations or other standards, it can be observed from the results presented in table 4 and fig. 4 that for all types of the beams, the closest to experimental results cracking moments were obtained according to str and aci 318. according to ec2 standard, larger errors were obtained. calculated results for all types of the beams are smaller than experimental values. specimen no. cracking moment (knm) experimental (kheder et al. 2010) calculated (str) calculated (ec2) calculated (aci 318) calculated (lm (1), λ ct,lim =λ c,lim ) calculated (lm (2), λ ct,lim ≠λ c,lim ) nsrc/402 10.00 8.35 (0.84) 4.77 (0.48) 7.68 (0.77) 7.92 (0.79) 10.00 (1.00) nsrc/603 10.46 8.83 (0.84) 5.05 (0.48) 8.23 (0.79) 8.88 (0.85) 10.46 (1.00) nsrc/982 11.40 8.90 (0.78) 5.08 (0.45) 8.71 (0.76) 9.67 (0.85) 11.40 (1.00) nsrc/1473 12.80 10.46 (0.82) 5.98 (0.47) 9.97 (0.78) 11.90 (0.93) 12.80 (1.00) hsrc/402 18.86 18.10 (0.96) 10.34 (0.55) 12.11 (0.64) 13.64 (0.72) 18.86 (1.00) hsrc/603 20.26 19.45 (0.96) 11.11 (0.55) 13.10 (0.65) 14.68 (0.72) 20.26 (1.00) hsrc/982 21.20 20.80 (0.98) 11.88 (0.56) 14.06 (0.66) 15.88 (0.75) 21.20 (1.00) hsrc/1473 22.60 21.82 (0.97) 12.47 (0.55) 14.65 (0.65) 17.45 (0.77) 22.60 (1.00) nhsrc/402 11.86 8.73 (0.74) 4.99 (0.42) 8.33 (0.70) 8.34 (0.70) 10.31 (0.87) nhsrc/603 12.33 9.33 (0.76) 5.33 (0.43) 8.90 (0.72) 9.35 (0.76) 10.82 (0.88) nhsrc/982 13.26 10.01 (0.75) 5.72 (0.43) 9.74 (0.73) 10.76 (0.81) 12.60 (0.95) nhsrc/1473 13.73 11.57 (0.84) 6.61 (0.48) 10.95 (0.80) 12.95 (0.94) 13.94 (1.02) journal of sustainable architecture and civil engineering 2014/3/8 90 two cases of the calculations were performed using layer method. in the first case, calculations were performed assuming that the values of the coefficient λ ct,lim are equal to λ c,lim (this coefficient was obtained in section 2, see table 1 and table 2, the interpolated values of λ c , lim were used depending on f cm ). in the second case, λ ct,lim was expressed from the experimental research results. case 1. the results of the calculations are given in table 4. the assumptions were made that coefficient λ ct,lim is equal to λ c,lim , k el,t and k el,c are equal to 0.4 for nsc and 0.6 for hsc. the values of the calculated cracking moments were obtained smaller than experimental: nsrc (7 – 21%), hsrc (23 – 28%), nhsrc (6 – 30%). the largest errors were obtained for hsrc and nhsrc beams. case 2. in this case, new approximate values of coefficient λ ct,lim were expressed from experimental data (nsrc and hsrc beams) for normal strength concrete (f cm ~21-23.6 mpa – λ ct,lim vary from 0.281 to 0.385) and for high strength concrete (f cm ~65.4-74.9 mpa – λ ct ,lim vary from 0.351 to 0.457). assumption was made that coefficients k el,t and k el,c are equal to 0.4 for normal strength concrete and 0.6 for high strength concrete. λ c,lim was used the same as in the case 1. it was assumed that for nsrc and hsrc beams m crc (calculated) is equal to m crc (experimental). expressed coefficients were used to calculate the cracking moments of composite beams. calculated values of m crc of nhsrc beams were obtained close to the experimentally determined values. the difference between calculated and experimental values of nhsrc beams varies from 2 to 13%. in the calculations of the flexural members cracking moment, it is very important to know the real limit elastic strain of the tensile concrete and the limit strain of tensile concrete at the peak stress, however design standards provide these approximate values only for compressive concrete. due to these reasons, coefficients k el,t and λ ct,lim can be corrected after more analysis. according to the performed calculations, it can be seen that until the cracking moment, compression zone of the concrete beam behaves elastically (λ c =1). however, the behaviour of tension concrete is quite mysterious, and it is difficult to estimate its real behaviour, therefore it should be noted that suggested coefficients are approximate. fig. 4 comparison of cracking moments conclusions 1 stress-strain curve calculated according to the expression (3) using kel,c and λc,lim coefficients has a good correlation with stress-strain relation given in design standard ec2. however, for cracking moment calculation more accurate expression (11) was suggested. 2 the values of the cracking moments which were calculated according to str and aci 318 are closer to the experimental values as compared to the calculations according to ec2. 3 λct,lim coefficients, expressed from the experimentally determined cracking moments of nsc and hsc beams are approximate and can be corrected after more experimental analysis. it is very important to know the real limit elastic strain of the tensile concrete and the limit strain at the peak tensile stress, which are not defined by design standards for the tensile concrete. 3. results analysis of the cracking moment calculations was performed according to str, ec2, aci 318 and lm. all results were compared with the experimental research results (kheder et al. 2010). due to this reason, the mean values of concrete properties were used in the calculation methods given in str, ec2 and aci 318. when the calculations were performed according to the available regulations or other standards, it can be observed from the results presented in table 4 and fig. 4 that for all types of the beams, the closest to experimental results cracking moments were obtained according to str and aci 318. according to ec2 standard, larger errors were obtained. calculated results for all types of the beams are smaller than experimental values. two cases of the calculations were performed using layer method. in the first case, calculations were performed assuming that the values of the coefficient λct,lim are equal to λc,lim (this coefficient was obtained in section 2, see table 1 and table 2, the interpolated values of λc,lim were used depending on fcm). in the second case, λct,lim was expressed from the experimental research results. case 1. the results of the calculations are given in table 4. the assumptions were made that coefficient λct,lim is equal to λc,lim, kel,t and kel,c are equal to 0.4 for nsc and 0.6 for hsc. the values of the calculated cracking moments were obtained smaller than experimental: nsrc (7 – 21%), hsrc (23 – 28%), nhsrc (6 – 30%). the largest errors were obtained for hsrc and nhsrc beams. case 2. in this case, new approximate values of coefficient λct,lim were expressed from experimental data (nsrc and hsrc beams) for normal strength concrete (fcm ~21-23.6 mpa – λct,lim vary from 0.281 to 0.385) and for high strength concrete (fcm~65.4-74.9 mpa – λct,lim vary from 0.351 to 0.457). assumption was made that coefficients kel,t and kel,c are equal to 0.4 for normal strength concrete and 0.6 for high strength concrete. λc,lim was used the same as in the case 1. it was assumed that for nsrc and hsrc beams mcrc (calculated) is equal to mcrc (experimental). expressed coefficients were used to calculate the cracking moments of composite beams. calculated values of mcrc of nhsrc beams were obtained close to the experimentally determined values. the difference between calculated and experimental values of nhsrc beams varies from 2 to 13%. in the calculations of the flexural members cracking moment, it is very important to know the real limit elastic strain of the tensile concrete and the limit strain of tensile concrete at the peak stress, however design standards provide these approximate values only for compressive concrete. due to these reasons, coefficients kel,t and λct,lim can be corrected after more analysis. according to the performed calculations, it can be seen that until the cracking moment, compression zone of the concrete beam behaves elastically (λc=1). however, the behaviour of tension concrete is quite mysterious, and it is difficult to estimate its real behaviour, therefore it should be noted that suggested coefficients are approximate. table 4. summary of experimental and calculated results (mean values of concrete properties were used in all calculations) specimen no. cracking moment (knm) experimental (kheder et al. 2010) calculated (str) calculated (ec2) calculated (aci 318) calculated (lm (1), λct,lim=λc,lim) calculated (lm (2), λct,lim≠λc,lim) nsrc/402 10.00 8.35 (0.84) 4.77 (0.48) 7.68 (0.77) 7.92 (0.79) 10.00 (1.00) nsrc/603 10.46 8.83 (0.84) 5.05 (0.48) 8.23 (0.79) 8.88 (0.85) 10.46 (1.00) nsrc/982 11.40 8.90 (0.78) 5.08 (0.45) 8.71 (0.76) 9.67 (0.85) 11.40 (1.00) nsrc/1473 12.80 10.46 (0.82) 5.98 (0.47) 9.97 (0.78) 11.90 (0.93) 12.80 (1.00) hsrc/402 18.86 18.10 (0.96) 10.34 (0.55) 12.11 (0.64) 13.64 (0.72) 18.86 (1.00) hsrc/603 20.26 19.45 (0.96) 11.11 (0.55) 13.10 (0.65) 14.68 (0.72) 20.26 (1.00) hsrc/982 21.20 20.80 (0.98) 11.88 (0.56) 14.06 (0.66) 15.88 (0.75) 21.20 (1.00) hsrc/1473 22.60 21.82 (0.97) 12.47 (0.55) 14.65 (0.65) 17.45 (0.77) 22.60 (1.00) nhsrc/402 11.86 8.73 (0.74) 4.99 (0.42) 8.33 (0.70) 8.34 (0.70) 10.31 (0.87) nhsrc/603 12.33 9.33 (0.76) 5.33 (0.43) 8.90 (0.72) 9.35 (0.76) 10.82 (0.88) nhsrc/982 13.26 10.01 (0.75) 5.72 (0.43) 9.74 (0.73) 10.76 (0.81) 12.60 (0.95) nhsrc/1473 13.73 11.57 (0.84) 6.61 (0.48) 10.95 (0.80) 12.95 (0.94) 13.94 (1.02) fig. 4. (pakeisti diagramas!) 91 journal of sustainable architecture and civil engineering 2014/3/8 4 it is observed that partial use of high strength concrete in compression zone of the composite beams can increase the cracking moment as compared to the normal strength concrete beams. tadas zingaila phd student kaunas university of technology, faculty of civil engineering and architecture main research area strength, stability and serviceability of reinforced concrete structures address studentu st. 48, lt-51367, kaunas, lithuania tel. +370 37 300473 e-mail: tadaszingaila@gmail.com mindaugas augonis associated professor kaunas university of technology, faculty of civil engineering and architecture, department of building structures main research area durability of engineering structures, strength and stability of reinforced concrete structures address studentu st. 48, lt-51367, kaunas, lithuania. tel. +370 37 300473 e-mail: mindaugas.augonis@ktu.lt about the authors acknowledgment aci committee 318. 2005. building code requirements for structural concrete and commentary (aci 318m-05). 436. augonis a., zadlauskas s. 2013. tampriai plastinių deformacijų įtaka gelžbetoninių stačiakampio skerspjūvio elementų pleišėjimo momentui ir deformacijoms. [the elastoplastic concrete strain influence on the cracking moment and deformation of rectangular reinforced concrete elements]. mechanika, 19(1), 5-11. http://dx.doi.org/10.5755/ j01.mech.19.1.3619 en 1992-1-1:2004. eurocode 2: design of concrete structures – part 1-1: general rules and rules for buildings. 225. iravani s., macgregor j. g. 1994. high performance concrete under high sustained compressive stresses. structural engineering report no. 200. department of civil engineering, university of alberta. kheder g. f., al kafaji j. m., dhiab r. m. 2010. flexural strength and cracking behavior of hybrid strength concrete beams. materials and structures, 43(8), 1097-1111. doi:10.1617/s11527-009-9569-9 kumar m., ma z., matovu m. mechanical properties of high-strength concrete. available at: http:// www.acsu.buffalo.edu/~mkumar2/wikiquake/ docs/reporthsc.pdf (accessed 15 march 2014). lapko a., sadowska-buraczewska b., tomaszewicz a. 2005. experimental and numerical analysis of flexural composite beams with partial use of high referencesstrength/high performance concrete. journal of civil engineering and management, 11(2), 115-120. http:// dx.doi.org/10.1080/13923730.2005.9636340 mosley w.h., bungey j.h., hulse r. 2007. reinforced concrete design to eurocode 2. 6th ed. basingstoke, palgrave macmillan. sadowska-buraczewska b., lapko a. 2007. the concept of strengthening of compressive zone in rc beams using hpc-hsc. in: proceedings of 9th international conference: modern building materials, structures and techniques, vilnus, lithuana, 752-757. shi c., mo y. l., dhonde h. b. 2008. high performance concrete. in: shi c., mo y. l. engineering materials for technological needs. high-performance construction materials: science and applications. singapore, world scientific publishing co. pte. ltd, 91-153. str 2.05.05:2005. design of concrete and reinforced concrete structures. 123 p. (in lithuanian). wight j.k., macgregor j. g. 2008. reinforced concrete. mechanics & design. 5th ed. prentice hall, new jersey. židonis i. strength calculation method for cross-section of reinforced concrete flexural member using curvilinear concrete stress diagram of ec-2. in: proceedings of the 11th international conference on modern building materials, structures and techniques (mbmst 2013), vilnius, lithuania. procedia engineering 57, 1309-1318. http://dx.doi.org/10.1016/j.proeng.2013.04.165 some data of experimental research were used from kheder et al., 2010 publication. 18 darnioji architektūra ir statyba 2014. no. 1(6) journal of sustainable architecture and civil engineering issn 2029–9990 environmental assessment of typical construction solutions in residential buildings in greece dimitrios bikas*, panagiotis chastas aristotle university of thessaloniki, dept. of civil engineering, laboratory of building construction and building physics, 54124 thessaloniki, greece. *corresponding author bikasd@civil.auth.gr http://dx.doi.org/10.5755/j01.sace.6.1.5949 climatic change has been one of the most important issues that occupies the scientific community around the world for many years now and affects economic, environmental and social policies. a continuous effort is made in order to manage and reduce the demand and consumption of both energy and materials, with the further goal of reducing environmental impacts in all sectors of the constantly developing society. one of the most important sectors that are being developed, following the ongoing global urbanization and population growth, striving to meet the increasing demand is the construction sector. for the proper management of the demand and consumption legalization has been adopted and methodologies and tools have been created. in the european union such an effort is the european community law 2002/91/ec which appears in the greek legislation by the law 3661/2008 and the regulation of the energy performance of buildings (κενακ, 2010), aiming to upgrade the existing building stock and compliance the future construction to the new requirements (τοτεε20701−2, 2010). this is an effort to reduce the environmental impacts from the energy consumption in the building sector. another important issue is the environmental impact from the materials and the stages of the construction of the building. in this scientific area efforts in europe have been made such as the environmental product declaration. a helpful tool for this analysis, which has not yet widely been used in greece, is the lca (life cycle assessment), which is used to calculate the environmental impact throughout the life cycle of a material, a product or a process. the aim of this paper was to provide the ideal construction solution for the opaque elements of the building envelope of residential buildings in greece and also create a database from which an engineer or a contractor, at the design stage of the building, can use to choose the solution with the least environmental impact depending on the climatic zone and its energy performance, according to the regulation of energy performance in buildings (κενακ, 2010), that is going to be constructed. keywords: life cycle assessment, residential buildings, energy consumption, u value, topsis. 1. introduction buildings are responsible for 40 % of the energy consumption in the european union. as indicated by the latest data of 2011 households are responsible for the 26.7 % of the final energy consumption in europe (eurostat, 2013). greece from the year 2007 (the entrance year into the economic crisis) has launched a downward trend in gross domestic consumption of primary energy. the same trend is observed at the building activity. since 2007 when the building sector began with 16,910,545 of constructed square meters building area there is a fall in 2012 to 2,641,200 square meters (el.stat., 2013). however from the year 1997 until 2007 the building activity was very intense and a significant building stock was constructed. as this is one of the most energy intensive parts of the greek and european economy there is an urgent need to reduce the energy consumption and environmental impacts in this sector. an effort for energy upgrading of buildings, in line with the greek legislation in 2013, is the european directive of the european parliament 2012/31/ee. its aim is to review periodically the provisions on energy performance of buildings, such as the regulation of the energy performance in buildings (κενακ, 2010), with the further goal all new buildings until the end of 2020 and new buildings occupied by public authorities until 2018 to become buildings with nearly zero energy consumption. even encourages the conversion of the existing building stock in buildings with nearly zero energy consumption with funded programs for insulation installation, replacing windows and doors, upgrading hvac systems etc. however this effort only attempts to reduce the environmental impact of the consumption of energy during the operation stage of the building. the environmental 19 impacts from the other stages of the life cycle of the building are ignored as they contribute with a small percentage at the total environmental impact of its life cycle. the aim of this paper is to calculate the environmental impact of typical construction solutions of the building envelope in residential buildings and for a square meter cross section. furthermore its aim is to provide the ideal solution, by using the multi-criteria analysis topsis, for each building element and for each climatic zone according to kenak. these results could be a helpful tool for a contractor or an engineer, in the design stage of a new building or in the design stage of an effort to upgrade the energy performance of the building stock, by choosing the ideal solution with the least environmental impact and also taking into account the energy performance of the building and the u value. 2. methods 2.1. typical construction solution of residential buildings in greece for this study, different construction solutions of building elements which constitute the building envelope of residential buildings in greece were selected. for the construction solutions of column are considered a cross section of reinforced concrete 30 cm thick, insulating material (polyurethane, extruded polystyrene (xps) and expanded polystyrene (eps)) and coating with plaster internally 2 cm thick and lime plaster externally 2.5 cm thick. a final covering with color is considered to the internal and external surface of the element. for construction solutions of beam and wall with reinforced concrete there is the same configuration as the column with the thickness difference of the concrete which is 25 cm and the amount of the reinforcing steel. as regards masonry is constructed with bricks of 18 cm thick (two layers of 9 cm thick), adhesive mortar for their connection, insulating material (rock wool, glass wool, extruded polystyrene (xps) and expanded polystyrene (eps)) coated with plaster internally 2 cm thick and lime plaster 2.5 cm thick externally and final covering with color in the internal and external surface. the variants differ in the use of an air layer, in the form of air gap, and its position and the mounting position of the insulating material. the flat roof construction solutions include accessible and inverted (with the insulation layer on the outside in order to protect the underlying layers), with variation in the thermal insulation material (polyurethane or extruded polystyrene (xps)). includes materials such as bitumen sheets, pvc sheet, hdpe sheet, reinforced concrete slab of 15 cm thick, gravel-concrete 8cm thick, lined with plaster in the internal surface 2 cm thick and exterior topcoat with gravel or stone slabs etc. the inclined roof construction includes solutions which differ in the use of thermal insulation material (expanded polystyrene (eps) or glass wool) and the use of concrete slab of 15cm or wood for the case of wooden roof with ceramic tiles. the construction solutions for flooring over pilotis differ in the type of insulation (extruded polystyrene (xps) and glass wool) with an outer covering (lime plaster and cement board respectively). and a final covering with wood, marble or ceramic tiles is considered in the internal surface. the main layer is the reinforced concrete slab 15 cm thick. 2.2. thickness of insulating material and u value as observed the main difference in the cross sections of the construction solutions of a building element is located in the choice of the insulating material. for the final configuration of the thickness of the insulating layer the thermal transmittance (u value) was calculated (eq.1). t a 2 2 g b r c t p c e c e r c i m l i p w t a l m c t u m i h g s s w ( c w o p ( c t c 2 o i c t w w taki and 2. m 2.1. gre buil resi con thic poly coa exte con elem rein colu is 2 mas laye insu poly with thic and laye mou con the und mat incl hd grav surf slab whi (exp con with ove poly (lim cov the con 2.2. of t in con ther u = whe w) ing d the met . ty eece f ldin iden f nsid ck, ysty ating ern nsid men nfor umn 25 c son ers ulat ysty h p ck e d ex er, unt nstru ins derl teri lud dpe vel face bs e ich pan ncre h c er p ysty me verin in ncre . th a the the nfig rma r = ere ; � int e u tho ypic e for ng e ntia for dere i yren g w ally dere nt. rced n w cm nry of ting yren plas exte xter in ting ucti sula lyin al des e sh -co e 2 etc. di nded ete cera pilo yren pla ng nter ete s hick as o con e c gura al tr sir + : � � � � – to a u va ods cal th elem al bu th ed a insu ne with y 2 ed for d c with and is 9 c g m ne ster erna rnal th g po ion atio ng l (po ma hee oncr cm th iffe d p slab amic otis ne aster wit rnal slab knes obs nstr hoi ation rans + ∑ �� – – la acco alue con his men uild he a c ulat (xp h pl 2.5 to r co conc h th d th con cm mat (xp int ally l su he f osit n so on l laye olyu ater et, rete m th he i er i poly b o c ti s d (xp r an th w l su b 15 ss o serv ruct ice n o smi 1 1 n i i d λ – th aye oun e. nstr stu nts ding co cros ting ps) last cm the ons cret he th he a nstr thi teri ps) tern y an urfac form tion luti laye ers) ure rial rein e 8c hick inc in ysty f 15 iles diffe ps) nd woo urfa 5 cm of in ved tion of of t ittan 1 i i + herm r th nt th ruc udy wh gs i ons ss s g ) a ter m th e i stru te t hick amo ruct ck) al ) an nall nd f ce. m o n of ion er o ), w tha s s nfo cm k an line the yren 5cm . t er ) an cem od, ace m th nsu the n so f th the nce ser mal hick he tion , d hich in g struc sect m and inte hick inte ctio ther kne ount ted ), ad (ro nd ly 2 fina th of f th s in on with ane such rce thic nd e ed r e u ne ( m o the in nd men ma . t hick ulat e m olut he th e (u r+ l re kne ene n so diffe h co gre ctio tion mate d e erna k. erna on re i ess t of w dhe ock exp 2 cm al co he v air he i nclu the h va or h a ed ck, exte roo use (ep or w e co the gla nt b arble the k. ing main tion ins ick u va alr esis ess ergy olut feren onst ece on n o rial expa ally a al a solu is t dif f th ith esiv k w pand m t ove vari r ga insu ude e ou aria r e as con lin erio of c of ps) woo onst e t ass boa e or e m g ma n di ns o sula knes alue stan (m y p tion nt titu e we so of r l and y 2 fin and utio the ffere he re br ve m woo ded thic erin ant ap, ulat ac utsi ation extru bitu ncre ned or to cons f th or od f truc type wo ard r ce main ater iffe of a atin ss o e) w nce m); erfo n of con ute t ere olut rein (po ded cm nal d e ons sam enc einf rick mor ol, d po ck a ng w ts d an ting cces ide n in ude um ete wit opc stru herm gla for t ctio e o ool) res eram n l rial eren bui g m of t was of � � form f re nstr the sel tion nfor oly po m th cov exte of me ce o forc ks o rtar gl olys and with diffe nd g m ssib in n th ed men sla th p coat uctio mal ass the on s of wi spe mic laye l an nce ildi mat the cal int – man esid ruc bu lect ns rced yure lyst hick veri erna f be co of th cing of 1 for ass styr d lim h co er in its mate ble a or he po sh ab plas t w on l in wo ca solu ins ith ctiv c til er nd u in ing teri in lcul tern the nce dent ction uildi ted. of d c etha tyre k an ing al s eam onfig he g st 18 r th w rene me olo n th po erial and rder the lyst heet of ster ith inc nsu ool) se o utio sula an vely es i is u va the ele ial. nsul late nal erm of tial n s ing f c onc ane, ene nd w surf m an gur con teel cm heir woo e (e pla r in he u ositi l. t d in r to erma tyre ts, 15 r in gra clud ulati an of w ons ation ou y). is c the alue e cr eme fo atin ed ( sur al the bu solu en colu cret , e (e lim with fac nd w ratio ncre l. a m th r co ol, eps aste n th use ion the nver o pr al i ene pv 5 c n th ave des ion nd t woo for n uter an cons e r e ross ent or ng (eq rfac con e bu ildi utio nvel umn te 3 ex eps me p co e o wal on ete as r hick onne ex s)) er 2 he in e of an fla rted rote insu e (x vc cm e in l or sol m the ode r fl (ex co nd a side rein s se is l the lay .1). ( ce ( ndu uild ings ons lope n 30 xtru s)) pla olor of ll w as wh rega k (t ecti xtru coa 2.5 nter f an nd at r d (w ect ulat xps sh thi nter r st luti mate use en r oor xtru over a fi ered nfor ecti oca e fi yer . (1) (m 2 uctiv ding s in of e of are cm ded and ster r is the with the hich ards two ion ded ated cm rnal n air the roof with the tion s)) eet ick rnal one ons erial e of roof ring ded ring final d in rced ions ated final the 2 .k/ vity g n f f e m d d r s e h e h s o , d d m l r e f h e n . , , l e s l f f g d g l n d s d l e / y co su of m re u wh it tra or m th ta cli pe cl en cli re lo zo cli co on cli zo fi oeff urfa f the axi egu calc u her is c ansm rder axi ey able ima erfo ext in flo lima nerg ima gio cat one ima onsi ne ima one ig. 1 ficie ace e ai th mu ulati culate re: � calc mit th r to mu app e 1. atic rma bui elem tern nclin ext ver bui elem oori pi atic gy p ac atic on. t ed i a) atic ider the atic (το 1. c ent (m 2 ir g he um ion ed ≤ � �� cula ttan he th o fu um pear ma zon ance ildin men nal f ned tern rtica ildin men ing iloti c zo per ccor c zo the in t to c zo red ey c zo οτ clim (w 2 .k ap cal u n of u≤ ���� ated nce hick ulfil u v r in maxim ne i e in ng nts flat roo nal al ng nts ove is one rfor rdin ones e sc the the one to are one τεε matic w/m k/w (m 2 cul va en max u ���� d (w of t kne ll t valu n the mum in g n bu or of er es o rma ng s de chem fou e co tha be e o δ ε207 c zo m.k w); � 2 .k/ late alue nerg x �� – w/m the ess the ues e g m va gree uildi c z of g ance to epen ma ur c olde at is e in rigi reg 701 nes k); � � �� /w d e p gy p – th m 2 .k ele of con s (ta gree alue ece ings clim zon 0,5 0,6 0,5 gre e in ke ndi tic clim est ( s lo n th inal gard 1−3 of � �� – ). u er perf herm k) eme the ndi able ek m e of ac s (τ mati ne α 50 60 50 eece n bu ena ng dep mati (cli cate he n lly dles , 20 gre � – the va clim form mal (eq ent e ins ition e 1 mar f th cor οτ c α e a uild ak on pict c zo ima ed i next lo ss o 010 eece the erm alue mat man tra q. 1 (w sula ns ) an rket herm rding εε2 cl zo 0 0 0 acco ding k g the tion one atic in a t co cate of 0). e (τ erm al r e w tic nce ansm ); � w/m 2 atin of nd t. mal g to 207 ima one 0,45 0,50 0,45 ord gs gree e he n (f es, f zon an a olde ed. alti τοτε mal resi was zo of mitt � �� 2 .k ng m (eq fol tran o th 01− atic β 5 0 5 ding ece eatin fig. from ne δ altit er c a itud τεε2 res ista c one bu tanc �� – k) (t mat q. 2 llow nsm he r −2, 2 c g to is ng 1) m th δ). tude clim all de a 207 sist ance om as uildi ce o – m tabl teri 2) a ws i mitta reg 201 clim zon 0, 0, 0, o th di deg de he w in e ov mat reg are 01− anc e of mpar s de ing of t maxi le 1 al w acc inte ance gula 0) mati ne γ ,40 ,45 ,40 he r ivid gree efine war n ea ver tic z gion inc −3, 2 ce o f th red efin s (t the imu ); was cord eger e (w ation ic γ reg ded e da es t rme ach r 50 zon ns clud 201 of e he a w ned tabl ele um s ch ding r va w/m n of cl z gula d in ays the er (c reg 00 m ne t loc ded 10) ext air l with d in le 1 (2 eme the hose g to alue m 2 .k) f en lima zone 0,3 0,4 0,3 atio nto of reg clim gion met than cate d in ern lay th n th ). 2) ent a erm en o th es a k) p nerg atic e δ 5 40 5 on fou eac gion mat n of ter, n th ed n th nal er he he as mal in he as er gy c of ur ch ns tic f a is he in his , (1) where: rsi – thermal resistance of internal surface (m2.k/ w); di – layer thickness (m); λi – thermal conductivity coefficient (w/m.k); rse – thermal resistance of external surface (m2.k/w); ral – thermal resistance of the air layer of the air gap (m2.k/w). the calculated u value was compared with the maximum u value per climatic zone as defined in the regulation of energy performance of buildings (table 1). t a 2 2 g b r c t p c e c e r c i m l i p w t a l m c t u m i h g s s w ( c w o p ( c t c 2 o i c t w w taki and 2. m 2.1. gre buil resi con thic poly coa exte con elem rein colu is 2 mas laye insu poly with thic and laye mou con the und mat incl hd grav surf slab whi (exp con with ove poly (lim cov the con 2.2. of t in con ther u = whe w) ing d the met . ty eece f ldin iden f nsid ck, ysty ating ern nsid men nfor umn 25 c son ers ulat ysty h p ck e d ex er, unt nstru ins derl teri lud dpe vel face bs e ich pan ncre h c er p ysty me verin in ncre . th a the the nfig rma r = ere ; � int e u tho ypic e for ng e ntia for dere i yren g w ally dere nt. rced n w cm nry of ting yren plas exte xter in ting ucti sula lyin al des e sh -co e 2 etc. di nded ete cera pilo yren pla ng nter ete s hick as o con e c gura al tr sir + : � � � � – to a u va ods cal th elem al bu th ed a insu ne with y 2 ed for d c with and is 9 c g m ne ster erna rnal th g po ion atio ng l (po ma hee oncr cm th iffe d p slab amic otis ne aster wit rnal slab knes obs nstr hoi ation rans + ∑ �� – – la acco alue con his men uild he a c ulat (xp h pl 2.5 to r co conc h th d th con cm mat (xp int ally l su he f osit n so on l laye olyu ater et, rete m th he i er i poly b o c ti s d (xp r an th w l su b 15 ss o serv ruct ice n o smi 1 1 n i i d λ – th aye oun e. nstr stu nts ding co cros ting ps) last cm the ons cret he th he a nstr thi teri ps) tern y an urfac form tion luti laye ers) ure rial rein e 8c hick inc in ysty f 15 iles diffe ps) nd woo urfa 5 cm of in ved tion of of t ittan 1 i i + herm r th nt th ruc udy wh gs i ons ss s g ) a ter m th e i stru te t hick amo ruct ck) al ) an nall nd f ce. m o n of ion er o ), w tha s s nfo cm k an line the yren 5cm . t er ) an cem od, ace m th nsu the n so f th the nce ser mal hick he tion , d hich in g struc sect m and inte hick inte ctio ther kne ount ted ), ad (ro nd ly 2 fina th of f th s in on with ane such rce thic nd e ed r e u ne ( m o the in nd men ma . t hick ulat e m olut he th e (u r+ l re kne ene n so diffe h co gre ctio tion mate d e erna k. erna on re i ess t of w dhe ock exp 2 cm al co he v air he i nclu the h va or h a ed ck, exte roo use (ep or w e co the gla nt b arble the k. ing main tion ins ick u va alr esis ess ergy olut feren onst ece on n o rial expa ally a al a solu is t dif f th ith esiv k w pand m t ove vari r ga insu ude e ou aria r e as con lin erio of c of ps) woo onst e t ass boa e or e m g ma n di ns o sula knes alue stan (m y p tion nt titu e we so of r l and y 2 fin and utio the ffere he re br ve m woo ded thic erin ant ap, ulat ac utsi ation extru bitu ncre ned or to cons f th or od f truc type wo ard r ce main ater iffe of a atin ss o e) w nce m); erfo n of con ute t ere olut rein (po ded cm nal d e ons sam enc einf rick mor ol, d po ck a ng w ts d an ting cces ide n in ude um ete wit opc stru herm gla for t ctio e o ool) res eram n l rial eren bui g m of t was of � � form f re nstr the sel tion nfor oly po m th cov exte of me ce o forc ks o rtar gl olys and with diffe nd g m ssib in n th ed men sla th p coat uctio mal ass the on s of wi spe mic laye l an nce ildi mat the cal int – man esid ruc bu lect ns rced yure lyst hick veri erna f be co of th cing of 1 for ass styr d lim h co er in its mate ble a or he po sh ab plas t w on l in wo ca solu ins ith ctiv c til er nd u in ing teri in lcul tern the nce dent ction uildi ted. of d c etha tyre k an ing al s eam onfig he g st 18 r th w rene me olo n th po erial and rder the lyst heet of ster ith inc nsu ool) se o utio sula an vely es i is u va the ele ial. nsul late nal erm of tial n s ing f c onc ane, ene nd w surf m an gur con teel cm heir woo e (e pla r in he u ositi l. t d in r to erma tyre ts, 15 r in gra clud ulati an of w ons ation ou y). is c the alue e cr eme fo atin ed ( sur al the bu solu en colu cret , e (e lim with fac nd w ratio ncre l. a m th r co ol, eps aste n th use ion the nver o pr al i ene pv 5 c n th ave des ion nd t woo for n uter an cons e r e ross ent or ng (eq rfac con e bu ildi utio nvel umn te 3 ex eps me p co e o wal on ete as r hick onne ex s)) er 2 he in e of an fla rted rote insu e (x vc cm e in l or sol m the ode r fl (ex co nd a side rein s se is l the lay .1). ( ce ( ndu uild ings ons lope n 30 xtru s)) pla olor of ll w as wh rega k (t ecti xtru coa 2.5 nter f an nd at r d (w ect ulat xps sh thi nter r st luti mate use en r oor xtru over a fi ered nfor ecti oca e fi yer . (1) (m 2 uctiv ding s in of e of are cm ded and ster r is the with the hich ards two ion ded ated cm rnal n air the roof with the tion s)) eet ick rnal one ons erial e of roof ring ded ring final d in rced ions ated final the 2 .k/ vity g n f f e m d d r s e h e h s o , d d m l r e f h e n . , , l e s l f f g d g l n d s d l e / y co su of m re u wh it tra or m th ta cli pe cl en cli re lo zo cli co on cli zo fi oeff urfa f the axi egu calc u her is c ansm rder axi ey able ima erfo ext in flo lima nerg ima gio cat one ima onsi ne ima one ig. 1 ficie ace e ai th mu ulati culate re: � calc mit th r to mu app e 1. atic rma bui elem tern nclin ext ver bui elem oori pi atic gy p ac atic on. t ed i a) atic ider the atic (το 1. c ent (m 2 ir g he um ion ed ≤ � �� cula ttan he th o fu um pear ma zon ance ildin men nal f ned tern rtica ildin men ing iloti c zo per ccor c zo the in t to c zo red ey c zo οτ clim (w 2 .k ap cal u n of u≤ ���� ated nce hick ulfil u v r in maxim ne i e in ng nts flat roo nal al ng nts ove is one rfor rdin ones e sc the the one to are one τεε matic w/m k/w (m 2 cul va en max u ���� d (w of t kne ll t valu n the mum in g n bu or of er es o rma ng s de chem fou e co tha be e o δ ε207 c zo m.k w); � 2 .k/ late alue nerg x �� – w/m the ess the ues e g m va gree uildi c z of g ance to epen ma ur c olde at is e in rigi reg 701 nes k); � � �� /w d e p gy p – th m 2 .k ele of con s (ta gree alue ece ings clim zon 0,5 0,6 0,5 gre e in ke ndi tic clim est ( s lo n th inal gard 1−3 of � �� – ). u er perf herm k) eme the ndi able ek m e of ac s (τ mati ne α 50 60 50 eece n bu ena ng dep mati (cli cate he n lly dles , 20 gre � – the va clim form mal (eq ent e ins ition e 1 mar f th cor οτ c α e a uild ak on pict c zo ima ed i next lo ss o 010 eece the erm alue mat man tra q. 1 (w sula ns ) an rket herm rding εε2 cl zo 0 0 0 acco ding k g the tion one atic in a t co cate of 0). e (τ erm al r e w tic nce ansm ); � w/m 2 atin of nd t. mal g to 207 ima one 0,45 0,50 0,45 ord gs gree e he n (f es, f zon an a olde ed. alti τοτε mal resi was zo of mitt � �� 2 .k ng m (eq fol tran o th 01− atic β 5 0 5 ding ece eatin fig. from ne δ altit er c a itud τεε2 res ista c one bu tanc �� – k) (t mat q. 2 llow nsm he r −2, 2 c g to is ng 1) m th δ). tude clim all de a 207 sist ance om as uildi ce o – m tabl teri 2) a ws i mitta reg 201 clim zon 0, 0, 0, o th di deg de he w in e ov mat reg are 01− anc e of mpar s de ing of t maxi le 1 al w acc inte ance gula 0) mati ne γ ,40 ,45 ,40 he r ivid gree efine war n ea ver tic z gion inc −3, 2 ce o f th red efin s (t the imu ); was cord eger e (w ation ic γ reg ded e da es t rme ach r 50 zon ns clud 201 of e he a w ned tabl ele um s ch ding r va w/m n of cl z gula d in ays the er (c reg 00 m ne t loc ded 10) ext air l with d in le 1 (2 eme the hose g to alue m 2 .k) f en lima zone 0,3 0,4 0,3 atio nto of reg clim gion met than cate d in ern lay th n th ). 2) ent a erm en o th es a k) p nerg atic e δ 5 40 5 on fou eac gion mat n of ter, n th ed n th nal er he he as mal in he as er gy c of ur ch ns tic f a is he in his , (2) where: t a 2 2 g b r c t p c e c e r c i m l i p w t a l m c t u m i h g s s w ( c w o p ( c t c 2 o i c t w w taki and 2. m 2.1. gre buil resi con thic poly coa exte con elem rein colu is 2 mas laye insu poly with thic and laye mou con the und mat incl hd grav surf slab whi (exp con with ove poly (lim cov the con 2.2. of t in con ther u = whe w) ing d the met . ty eece f ldin iden f nsid ck, ysty ating ern nsid men nfor umn 25 c son ers ulat ysty h p ck e d ex er, unt nstru ins derl teri lud dpe vel face bs e ich pan ncre h c er p ysty me verin in ncre . th a the the nfig rma r = ere ; � int e u tho ypic e for ng e ntia for dere i yren g w ally dere nt. rced n w cm nry of ting yren plas exte xter in ting ucti sula lyin al des e sh -co e 2 etc. di nded ete cera pilo yren pla ng nter ete s hick as o con e c gura al tr sir + : � � � � – to a u va ods cal th elem al bu th ed a insu ne with y 2 ed for d c with and is 9 c g m ne ster erna rnal th g po ion atio ng l (po ma hee oncr cm th iffe d p slab amic otis ne aster wit rnal slab knes obs nstr hoi ation rans + ∑ �� – – la acco alue con his men uild he a c ulat (xp h pl 2.5 to r co conc h th d th con cm mat (xp int ally l su he f osit n so on l laye olyu ater et, rete m th he i er i poly b o c ti s d (xp r an th w l su b 15 ss o serv ruct ice n o smi 1 1 n i i d λ – th aye oun e. nstr stu nts ding co cros ting ps) last cm the ons cret he th he a nstr thi teri ps) tern y an urfac form tion luti laye ers) ure rial rein e 8c hick inc in ysty f 15 iles diffe ps) nd woo urfa 5 cm of in ved tion of of t ittan 1 i i + herm r th nt th ruc udy wh gs i ons ss s g ) a ter m th e i stru te t hick amo ruct ck) al ) an nall nd f ce. m o n of ion er o ), w tha s s nfo cm k an line the yren 5cm . t er ) an cem od, ace m th nsu the n so f th the nce ser mal hick he tion , d hich in g struc sect m and inte hick inte ctio ther kne ount ted ), ad (ro nd ly 2 fina th of f th s in on with ane such rce thic nd e ed r e u ne ( m o the in nd men ma . t hick ulat e m olut he th e (u r+ l re kne ene n so diffe h co gre ctio tion mate d e erna k. erna on re i ess t of w dhe ock exp 2 cm al co he v air he i nclu the h va or h a ed ck, exte roo use (ep or w e co the gla nt b arble the k. ing main tion ins ick u va alr esis ess ergy olut feren onst ece on n o rial expa ally a al a solu is t dif f th ith esiv k w pand m t ove vari r ga insu ude e ou aria r e as con lin erio of c of ps) woo onst e t ass boa e or e m g ma n di ns o sula knes alue stan (m y p tion nt titu e we so of r l and y 2 fin and utio the ffere he re br ve m woo ded thic erin ant ap, ulat ac utsi ation extru bitu ncre ned or to cons f th or od f truc type wo ard r ce main ater iffe of a atin ss o e) w nce m); erfo n of con ute t ere olut rein (po ded cm nal d e ons sam enc einf rick mor ol, d po ck a ng w ts d an ting cces ide n in ude um ete wit opc stru herm gla for t ctio e o ool) res eram n l rial eren bui g m of t was of � � form f re nstr the sel tion nfor oly po m th cov exte of me ce o forc ks o rtar gl olys and with diffe nd g m ssib in n th ed men sla th p coat uctio mal ass the on s of wi spe mic laye l an nce ildi mat the cal int – man esid ruc bu lect ns rced yure lyst hick veri erna f be co of th cing of 1 for ass styr d lim h co er in its mate ble a or he po sh ab plas t w on l in wo ca solu ins ith ctiv c til er nd u in ing teri in lcul tern the nce dent ction uildi ted. of d c etha tyre k an ing al s eam onfig he g st 18 r th w rene me olo n th po erial and rder the lyst heet of ster ith inc nsu ool) se o utio sula an vely es i is u va the ele ial. nsul late nal erm of tial n s ing f c onc ane, ene nd w surf m an gur con teel cm heir woo e (e pla r in he u ositi l. t d in r to erma tyre ts, 15 r in gra clud ulati an of w ons ation ou y). is c the alue e cr eme fo atin ed ( sur al the bu solu en colu cret , e (e lim with fac nd w ratio ncre l. a m th r co ol, eps aste n th use ion the nver o pr al i ene pv 5 c n th ave des ion nd t woo for n uter an cons e r e ross ent or ng (eq rfac con e bu ildi utio nvel umn te 3 ex eps me p co e o wal on ete as r hick onne ex s)) er 2 he in e of an fla rted rote insu e (x vc cm e in l or sol m the ode r fl (ex co nd a side rein s se is l the lay .1). ( ce ( ndu uild ings ons lope n 30 xtru s)) pla olor of ll w as wh rega k (t ecti xtru coa 2.5 nter f an nd at r d (w ect ulat xps sh thi nter r st luti mate use en r oor xtru over a fi ered nfor ecti oca e fi yer . (1) (m 2 uctiv ding s in of e of are cm ded and ster r is the with the hich ards two ion ded ated cm rnal n air the roof with the tion s)) eet ick rnal one ons erial e of roof ring ded ring final d in rced ions ated final the 2 .k/ vity g n f f e m d d r s e h e h s o , d d m l r e f h e n . , , l e s l f f g d g l n d s d l e / y co su of m re u wh it tra or m th ta cli pe cl en cli re lo zo cli co on cli zo fi oeff urfa f the axi egu calc u her is c ansm rder axi ey able ima erfo ext in flo lima nerg ima gio cat one ima onsi ne ima one ig. 1 ficie ace e ai th mu ulati culate re: � calc mit th r to mu app e 1. atic rma bui elem tern nclin ext ver bui elem oori pi atic gy p ac atic on. t ed i a) atic ider the atic (το 1. c ent (m 2 ir g he um ion ed ≤ � �� cula ttan he th o fu um pear ma zon ance ildin men nal f ned tern rtica ildin men ing iloti c zo per ccor c zo the in t to c zo red ey c zo οτ clim (w 2 .k ap cal u n of u≤ ���� ated nce hick ulfil u v r in maxim ne i e in ng nts flat roo nal al ng nts ove is one rfor rdin ones e sc the the one to are one τεε matic w/m k/w (m 2 cul va en max u ���� d (w of t kne ll t valu n the mum in g n bu or of er es o rma ng s de chem fou e co tha be e o δ ε207 c zo m.k w); � 2 .k/ late alue nerg x �� – w/m the ess the ues e g m va gree uildi c z of g ance to epen ma ur c olde at is e in rigi reg 701 nes k); � � �� /w d e p gy p – th m 2 .k ele of con s (ta gree alue ece ings clim zon 0,5 0,6 0,5 gre e in ke ndi tic clim est ( s lo n th inal gard 1−3 of � �� – ). u er perf herm k) eme the ndi able ek m e of ac s (τ mati ne α 50 60 50 eece n bu ena ng dep mati (cli cate he n lly dles , 20 gre � – the va clim form mal (eq ent e ins ition e 1 mar f th cor οτ c α e a uild ak on pict c zo ima ed i next lo ss o 010 eece the erm alue mat man tra q. 1 (w sula ns ) an rket herm rding εε2 cl zo 0 0 0 acco ding k g the tion one atic in a t co cate of 0). e (τ erm al r e w tic nce ansm ); � w/m 2 atin of nd t. mal g to 207 ima one 0,45 0,50 0,45 ord gs gree e he n (f es, f zon an a olde ed. alti τοτε mal resi was zo of mitt � �� 2 .k ng m (eq fol tran o th 01− atic β 5 0 5 ding ece eatin fig. from ne δ altit er c a itud τεε2 res ista c one bu tanc �� – k) (t mat q. 2 llow nsm he r −2, 2 c g to is ng 1) m th δ). tude clim all de a 207 sist ance om as uildi ce o – m tabl teri 2) a ws i mitta reg 201 clim zon 0, 0, 0, o th di deg de he w in e ov mat reg are 01− anc e of mpar s de ing of t maxi le 1 al w acc inte ance gula 0) mati ne γ ,40 ,45 ,40 he r ivid gree efine war n ea ver tic z gion inc −3, 2 ce o f th red efin s (t the imu ); was cord eger e (w ation ic γ reg ded e da es t rme ach r 50 zon ns clud 201 of e he a w ned tabl ele um s ch ding r va w/m n of cl z gula d in ays the er (c reg 00 m ne t loc ded 10) ext air l with d in le 1 (2 eme the hose g to alue m 2 .k) f en lima zone 0,3 0,4 0,3 atio nto of reg clim gion met than cate d in ern lay th n th ). 2) ent a erm en o th es a k) p nerg atic e δ 5 40 5 on fou eac gion mat n of ter, n th ed n th nal er he he as mal in he as er gy c of ur ch ns tic f a is he in his – thermal transmittance of the element as it is calculated (w/m2.k) (eq. 1); t a 2 2 g b r c t p c e c e r c i m l i p w t a l m c t u m i h g s s w ( c w o p ( c t c 2 o i c t w w taki and 2. m 2.1. gre buil resi con thic poly coa exte con elem rein colu is 2 mas laye insu poly with thic and laye mou con the und mat incl hd grav surf slab whi (exp con with ove poly (lim cov the con 2.2. of t in con ther u = whe w) ing d the met . ty eece f ldin iden f nsid ck, ysty ating ern nsid men nfor umn 25 c son ers ulat ysty h p ck e d ex er, unt nstru ins derl teri lud dpe vel face bs e ich pan ncre h c er p ysty me verin in ncre . th a the the nfig rma r = ere ; � int e u tho ypic e for ng e ntia for dere i yren g w ally dere nt. rced n w cm nry of ting yren plas exte xter in ting ucti sula lyin al des e sh -co e 2 etc. di nded ete cera pilo yren pla ng nter ete s hick as o con e c gura al tr sir + : � � � � – to a u va ods cal th elem al bu th ed a insu ne with y 2 ed for d c with and is 9 c g m ne ster erna rnal th g po ion atio ng l (po ma hee oncr cm th iffe d p slab amic otis ne aster wit rnal slab knes obs nstr hoi ation rans + ∑ �� – – la acco alue con his men uild he a c ulat (xp h pl 2.5 to r co conc h th d th con cm mat (xp int ally l su he f osit n so on l laye olyu ater et, rete m th he i er i poly b o c ti s d (xp r an th w l su b 15 ss o serv ruct ice n o smi 1 1 n i i d λ – th aye oun e. nstr stu nts ding co cros ting ps) last cm the ons cret he th he a nstr thi teri ps) tern y an urfac form tion luti laye ers) ure rial rein e 8c hick inc in ysty f 15 iles diffe ps) nd woo urfa 5 cm of in ved tion of of t ittan 1 i i + herm r th nt th ruc udy wh gs i ons ss s g ) a ter m th e i stru te t hick amo ruct ck) al ) an nall nd f ce. m o n of ion er o ), w tha s s nfo cm k an line the yren 5cm . t er ) an cem od, ace m th nsu the n so f th the nce ser mal hick he tion , d hich in g struc sect m and inte hick inte ctio ther kne ount ted ), ad (ro nd ly 2 fina th of f th s in on with ane such rce thic nd e ed r e u ne ( m o the in nd men ma . t hick ulat e m olut he th e (u r+ l re kne ene n so diffe h co gre ctio tion mate d e erna k. erna on re i ess t of w dhe ock exp 2 cm al co he v air he i nclu the h va or h a ed ck, exte roo use (ep or w e co the gla nt b arble the k. ing main tion ins ick u va alr esis ess ergy olut feren onst ece on n o rial expa ally a al a solu is t dif f th ith esiv k w pand m t ove vari r ga insu ude e ou aria r e as con lin erio of c of ps) woo onst e t ass boa e or e m g ma n di ns o sula knes alue stan (m y p tion nt titu e we so of r l and y 2 fin and utio the ffere he re br ve m woo ded thic erin ant ap, ulat ac utsi ation extru bitu ncre ned or to cons f th or od f truc type wo ard r ce main ater iffe of a atin ss o e) w nce m); erfo n of con ute t ere olut rein (po ded cm nal d e ons sam enc einf rick mor ol, d po ck a ng w ts d an ting cces ide n in ude um ete wit opc stru herm gla for t ctio e o ool) res eram n l rial eren bui g m of t was of � � form f re nstr the sel tion nfor oly po m th cov exte of me ce o forc ks o rtar gl olys and with diffe nd g m ssib in n th ed men sla th p coat uctio mal ass the on s of wi spe mic laye l an nce ildi mat the cal int – man esid ruc bu lect ns rced yure lyst hick veri erna f be co of th cing of 1 for ass styr d lim h co er in its mate ble a or he po sh ab plas t w on l in wo ca solu ins ith ctiv c til er nd u in ing teri in lcul tern the nce dent ction uildi ted. of d c etha tyre k an ing al s eam onfig he g st 18 r th w rene me olo n th po erial and rder the lyst heet of ster ith inc nsu ool) se o utio sula an vely es i is u va the ele ial. nsul late nal erm of tial n s ing f c onc ane, ene nd w surf m an gur con teel cm heir woo e (e pla r in he u ositi l. t d in r to erma tyre ts, 15 r in gra clud ulati an of w ons ation ou y). is c the alue e cr eme fo atin ed ( sur al the bu solu en colu cret , e (e lim with fac nd w ratio ncre l. a m th r co ol, eps aste n th use ion the nver o pr al i ene pv 5 c n th ave des ion nd t woo for n uter an cons e r e ross ent or ng (eq rfac con e bu ildi utio nvel umn te 3 ex eps me p co e o wal on ete as r hick onne ex s)) er 2 he in e of an fla rted rote insu e (x vc cm e in l or sol m the ode r fl (ex co nd a side rein s se is l the lay .1). ( ce ( ndu uild ings ons lope n 30 xtru s)) pla olor of ll w as wh rega k (t ecti xtru coa 2.5 nter f an nd at r d (w ect ulat xps sh thi nter r st luti mate use en r oor xtru over a fi ered nfor ecti oca e fi yer . (1) (m 2 uctiv ding s in of e of are cm ded and ster r is the with the hich ards two ion ded ated cm rnal n air the roof with the tion s)) eet ick rnal one ons erial e of roof ring ded ring final d in rced ions ated final the 2 .k/ vity g n f f e m d d r s e h e h s o , d d m l r e f h e n . , , l e s l f f g d g l n d s d l e / y co su of m re u wh it tra or m th ta cli pe cl en cli re lo zo cli co on cli zo fi oeff urfa f the axi egu calc u her is c ansm rder axi ey able ima erfo ext in flo lima nerg ima gio cat one ima onsi ne ima one ig. 1 ficie ace e ai th mu ulati culate re: � calc mit th r to mu app e 1. atic rma bui elem tern nclin ext ver bui elem oori pi atic gy p ac atic on. t ed i a) atic ider the atic (το 1. c ent (m 2 ir g he um ion ed ≤ � �� cula ttan he th o fu um pear ma zon ance ildin men nal f ned tern rtica ildin men ing iloti c zo per ccor c zo the in t to c zo red ey c zo οτ clim (w 2 .k ap cal u n of u≤ ���� ated nce hick ulfil u v r in maxim ne i e in ng nts flat roo nal al ng nts ove is one rfor rdin ones e sc the the one to are one τεε matic w/m k/w (m 2 cul va en max u ���� d (w of t kne ll t valu n the mum in g n bu or of er es o rma ng s de chem fou e co tha be e o δ ε207 c zo m.k w); � 2 .k/ late alue nerg x �� – w/m the ess the ues e g m va gree uildi c z of g ance to epen ma ur c olde at is e in rigi reg 701 nes k); � � �� /w d e p gy p – th m 2 .k ele of con s (ta gree alue ece ings clim zon 0,5 0,6 0,5 gre e in ke ndi tic clim est ( s lo n th inal gard 1−3 of � �� – ). u er perf herm k) eme the ndi able ek m e of ac s (τ mati ne α 50 60 50 eece n bu ena ng dep mati (cli cate he n lly dles , 20 gre � – the va clim form mal (eq ent e ins ition e 1 mar f th cor οτ c α e a uild ak on pict c zo ima ed i next lo ss o 010 eece the erm alue mat man tra q. 1 (w sula ns ) an rket herm rding εε2 cl zo 0 0 0 acco ding k g the tion one atic in a t co cate of 0). e (τ erm al r e w tic nce ansm ); � w/m 2 atin of nd t. mal g to 207 ima one 0,45 0,50 0,45 ord gs gree e he n (f es, f zon an a olde ed. alti τοτε mal resi was zo of mitt � �� 2 .k ng m (eq fol tran o th 01− atic β 5 0 5 ding ece eatin fig. from ne δ altit er c a itud τεε2 res ista c one bu tanc �� – k) (t mat q. 2 llow nsm he r −2, 2 c g to is ng 1) m th δ). tude clim all de a 207 sist ance om as uildi ce o – m tabl teri 2) a ws i mitta reg 201 clim zon 0, 0, 0, o th di deg de he w in e ov mat reg are 01− anc e of mpar s de ing of t maxi le 1 al w acc inte ance gula 0) mati ne γ ,40 ,45 ,40 he r ivid gree efine war n ea ver tic z gion inc −3, 2 ce o f th red efin s (t the imu ); was cord eger e (w ation ic γ reg ded e da es t rme ach r 50 zon ns clud 201 of e he a w ned tabl ele um s ch ding r va w/m n of cl z gula d in ays the er (c reg 00 m ne t loc ded 10) ext air l with d in le 1 (2 eme the hose g to alue m 2 .k) f en lima zone 0,3 0,4 0,3 atio nto of reg clim gion met than cate d in ern lay th n th ). 2) ent a erm en o th es a k) p nerg atic e δ 5 40 5 on fou eac gion mat n of ter, n th ed n th nal er he he as mal in he as er gy c of ur ch ns tic f a is he in his – maximum thermal transmittance of the element (w/m2.k) (table 1); the thickness of the insulating material was chosen in order to fulfill the conditions of (eq. 2) according to the maximum u values (table 1) and follows integer values as they appear in the greek market. table 1. maximum value of thermal transmittance (w/m2.k) per climatic zone in greece according to the regulation of energy performance in buildings (τοτεε20701−2, 2010) building elements climatic zone α climatic zone β climatic zone γ climatic zone δ external flat or inclined roof 0,50 0,45 0,40 0,35 external vertical building elements 0,60 0,50 0,45 0,40 flooring over pilotis 0,50 0,45 0,40 0,35 climatic zones of greece according to the regulation of energy performance in buildings according to kenak greece is divided into four climatic zones depending on the heating degree days of each region. the schematic depiction (fig. 1) defines the regions located in the four climatic zones, from the warmer (climatic zone a) to the coldest (climatic zone δ). in each region of a climatic zone that is located in an altitude over 500 meter, is considered to be in the next colder climatic zone than the one they are originally located. all regions located in climatic zone δ regardless of altitude are included in this zone (τοτεε20701−3, 2010). 20 fig. 1. climatic zones of greece (τοτεε20701−3, 2010) 2.3. life cycle assessment the goal and scope of this lca is to calculate the environmental impact of the typical constructions solutions of the opaque building elements and for a square meter cross section. this lca includes environmental impacts from the extraction and production of the material until the material reaches door of the factory and is ready for sale. also includes the transportation from the factory to the construction site which is considered 100 km. the energy that is required for the construction of the building element in mega joules (mj) is also taken into account (αραϊλόπουλος & χαστάς, 2009). the maintenance stage of the building element is included. the life cycle of the building element is considered 75 years. for the insulation 35–40 years, so it participates in the life cycle of the building element with two life cycles. the same assumption is done for the layers that need to be replaced along with the insulation to complete the maintenance stage. the color covering of the internal surface participates with six life cycles and the external with two in the life cycle of the building element. the lca also includes environmental impacts from the energy that is required for the demolition of the construction in mega joules (mj). furthermore the transportation from the construction site after the demolition to the place for the final disposal of the materials which is considered 100 km. and at last the environmental impacts from the final disposal of the materials of the building element at the end of its life cycle. the materials and transportation vehicles of life cycle inventory are secondary data from libraries (ecoinvent system and unit processes, idemat 2001, eth-esu system and unit processes). the energy that is required for the demolition and construction of the building elements was calculated and the production energy mix of greece is also secondary data that was adapted to the latest data from the energy regulatory authority and the hellenic transmission system operator. the method that was used for the life cycle assessment of the construction solutions is cml baseline (preconsultants, 2008). it is a classification method for lca analysis that is based on the method and database of the cml university of leiden (cml, 2013). for this lca were chosen six of the ten impact categories of this method (table 2). table 2. environmental impact categories environmental impact categories units ozone layer depletion (odp) kg cfc-11 equal photochemical oxidation (pocp) kg c2h4 equal global warming (gwp100) kg co2 equal acidification (ap) kg so2 equal abiotic depletion (adp) kg sb equal eutrophication (ep) kg po4 equal 2.4. multi-criteria decision analysis method topsis the topsis (technique for order or preference by similarity to ideal solution) is a method for multi-criteria analysis developed by hwang and yoon. it is based on the logic that the chosen alternative has the shortest distance from the positive ideal solution and the greater distance from the negative ideal solution. it is a method that compares a set of options by determining the weights for each criterion, normalizing the values for each criterion and calculating the geometrical distance of each alternative and the ideal alternative, which is also the best value for each criterion (hwang & yoon, 1981). in our case the alternatives are the different construction solutions for each building element of the building envelope. the criteria are the calculated environmental impact of the life cycle of the construction solutions in the six impact categories of cml baseline method. for determining the weights for each criterion it was considered the weighting set of the method cml baseline (table 3) in order to maintain the objectivity of this analysis. table 3. weighting set of method cml baseline used in topsis analysis environmental impact categories weighting set ozone layer depletion (odp) 6.74 e-11 photochemical oxidation (pocp) 3.66 e-11 global warming (gwp100) 8.02 e-11 acidification (ap) 2.08 e-13 abiotic depletion (adp) 1.20 e-7 eutrophication (ep) 1.21 e-10 for the identification of the positive and negative ideal solution because the criteria are environmental impacts were considered to be cost criteria. the topsis analysis was used for the ranking of the construction solutions of each building element of the building envelope, in order to provide the ideal one, and for each one of the four climatic zones (κενακ, 2010). 2.5. the influence of u value in the identification of the ideal solution the calculation of the thickness of the insulation layer was carried out for integer values as they appear in the greek market. it was noticed that for a construction solution, in order to fulfil the conditions of the u value (eq. 2), when the thickness of the insulation layer was high the calculated u value of the building element had 21 significant deviation from the maximum u value. the construction solution with the greater thickness of insulation materials, as the lca analysis and the environmental impacts are based on the quantities of the materials (kg) that compose the construction solution, appears to have the greater environmental impact. this was noticed mainly in the comparison between construction solutions that differ only at the kind of the insulation material. as a result the construction solution with the greater thickness and the lower u value would have more environmental impacts and would be far from the ideal solution at the final ranking of the construction solutions with topsis. however this solution, with considerable distance from the maximum u value, would probably appear to have high improved energy performance during the life cycle of the building element and the building envelope. and probably would be one of the factors that could reduce the energy consumption of a building. from this consideration it was decided after running the first lca and topsis analysis to carry out a second one where the effect of the u value in each construction solution and its environmental impact will be taken into account. in order to take into account the effect of the u value it was necessary to provide one more weight at the weighting set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m2) west wall 10.08 window glazing 7.00 north wall 15.40 south wall 15.40 east wall 10.08 floor 19.80 roof-ceiling 19.80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m2.k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m2.k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis , (3) where: set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis – thermal transmittance of the element as it is calculated (w/m2.k) (eq. 1); set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis – maximum thermal transmittance of the element (w/m2.k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m2.k of the u value: set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100 % u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis , (4) where: eu – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m2 ×year); du – the numerical distance of the maximum and calculated u value of the building element (eq. 3); de – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m2.k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value : 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis , (5) where: set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' u total e − (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m2); eu – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m2×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m2 in order to be imported in the life cycle of the building element. set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis , (6) 22 where: set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m2); set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' u total u total e e − − (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m2); 3.6–1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis , (7) where: set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final e (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis – the final energy that is imported in the life cycle of the building element (mj/m2); set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis – the total energy that is required for the construction and demolition of the building element (mj/m2); set of topsis analysis for this criterion. however as in the first place it was decided to use the weighting set of the cml baseline method, in order to preserve the objectivity of this analysis, the use of an extra weight would undermine this effort. so it was decided to use a typical construction that is provided by iso 13790/2008 for tests, in order to quantify the effect of the u value in terms of energy and to be imported in the life cycle analysis, without providing an extra weight and criterion in the topsis analysis. 2.6. the influence of u value in the energy performance of the building elements the software that was used for this analysis is tee kenak, the software that is used for the inspections of energy performance of buildings in greece. the method that is used by the software is the monthly method of energy simulations in buildings. for the completeness of this analysis it was considered a theoretical heating and cooling system according to regulation of energy performance of buildings. the typical construction that is examined is provided for tests by iso 13790/2008 (table 4) and takes no account of thermal bridges. table 4. dimensions of construction (iso13790, 2008) building element area (m 2 ) west wall 10,08 window glazing 7,00 north wall 15,40 south wall 15,40 east wall 10,08 floor 19,80 roof-ceiling 19,80 in order to calculate the influence of the u value in the consumption of the primary energy by end use the maximum u value (table 1), depending on the climatic zone, of all building elements is defined. then the u value of the examined element is changing with a descending step 0.05 w/m 2 .k while all the other building elements keep their original maximum u value. the procedure is carried out for all the opaque building elements and for the four climatic zones of greece. then from the analysis and the linear trends of the results, the reduction in the primary energy consumption by end use of the building is calculated for a reduction of 0.01 w/m 2 .k of the u value of each building element and for the four climatic zones. 2.7. quantification of the effect of the u value in the life cycle of the building element in order to quantify the effect of the reduction of u value and to import it in the life cycle of each construction solution is taken into account the numerical distance of the calculated u value of the construction solution from the maximum u value of the climatic zone: max calculated du u u= − (3) where: � ���������� – thermal transmittance of the element as it is calculated (w/m 2 .k) (eq. 1); � ��� – maximum thermal transmittance of the element (w/m 2 .k) (table 1). then it is multiplied by the change in the consumption of primary energy by end use for a reduction of 0.01 w/m 2 .k of the u value: 100% u e du de= × × (4) where: � � – the contribution of u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); �� – the numerical distance of the maximum and calculated u value of the building element (eq. 3); �� – the reduction in the primary energy consumption by end use of the building for a reduction of 0.01 w/m 2 .k of the u value. this contribution is multiplied by the duration of the life cycle of the building elements which was considered to be seventy five years. ' 75 u total u e e − = × (5) where: �′ ������� – the contribution of u value of the element to the reduction of primary energy consumption by end use during the life cycle of the building element (kwh/m 2 ); � � – the contribution of the u value of the element to the reduction of annual primary energy consumption by end use (kwh/m 2 ×year); 75 – the duration of the life cycle of the building element (years). finally this contribution is converted from kwh/m2 to mj/m 2 in order to be imported in the life cycle of the building element. ' 3.6 u total u total e e − − = × (6) where: � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during the life cycle of the building element (mj/m 2 ); �′ ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle (kwh/m 2 ); 3.6 – 1.0 kwh equals to 3.6 mj. for each construction solution this contribution is imported as a benefit during its life cycle in the sector of energy. it is added with a minus sign to the total energy that is required for the stages of the construction and demolition of the building element. final calculated u total e e e − = − (7) where: � ����� – the final energy that is imported in the life cycle of the building element (mj/m 2 ); � ���������� – the total energy that is required for the construction and demolition of the building element (mj/m 2 ); � ������� – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m 2 ). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis – the contribution of u value of the building element to the reduction of primary energy consumption by end use during its life cycle of (mj/m2). then the lca and topsis analysis were carried out again with the modified data in the sector of energy. 3. results 3.1. ideal solutions from the lca and tosis analysis the construction solutions of the building element inclined roof show a significant difference as the optimal solutions are those with the use of wood than concrete for as the main material for its construction (table 5). for the same construction solution of inclined roof with the only difference the insulating material glass wool overrides the use of extruded polystyrene (xps). table 5. optimal solutions for the building element of sloping roof climatic zones inclined roof α roof with wood, ceramic tiles and insulation glass wool (2 cm) β roof with wood, ceramic tiles and insulation glass wool (2 cm) γ roof with wood, ceramic tiles and insulation glass wool (3 cm) δ roof with wood, ceramic tiles and insulation glass wool (4 cm) for the construction solutions of masonry in bricks the optimal solutions for all climatic zones, with the same ranking, are the walls with an air layer (air gap) and rock wool for insulation in the middle of the section, the ventilated walls with rock wool for insulation in the external surface and the masonry with rock wool for insulation in the internal surface and final coating with plasterboard (table 6). between the four remaining similar profiles of masonry that were examined, with unique variation the insulating material, is observed as better solution the use glass wool rather than rock wool, expanded polystyrene and extruded polystyrene without observed differences between the four climatic zones. table 6. optimal solutions for the building element masonry in bricks climatic zones masonry in bricks α air gap (5 cm) with no contact with the external air and insulation rock wool (5 cm) in the middle ventilated wall with insulation rock wool (4 cm) in the external surface insulation rock wool (4 cm) in the internal surface and final covering with plasterboard β air gap (5 cm) with no contact with the external air and insulation rock wool (6 cm) in the middle ventilated wall with insulation rock wool (5 cm) in the external surface insulation rock wool (6 cm) in the internal surface and final covering with plasterboard γ air gap (5 cm) with no contact with the external air and insulation rock wool (7 cm) in the middle ventilated wall with insulation rock wool (6 cm) in the external surface insulation rock wool (6 cm) in the internal surface and final covering with plasterboard δ air gap (5 cm) with no contact with the external air and insulation rock wool (7 cm) in the middle ventilated wall with insulation rock wool (7 cm) in the external surface insulation rock wool (7 cm) in the internal surface and final covering with plasterboard regarding construction solutions of the flat roof the inverted roof appears to be better solution than the compatible one (table 7). table 7. optimal solutions for the building element flat roof climatic zones flat roof α inverted flat roof with xps (6 cm) β inverted flat roof with xps (7 cm) γ inverted flat roof with xps (8 cm) δ inverted flat roof with xps (9 cm) for the same construction solution of flat roof, with the only difference the insulating material, xps appears to be a better solution than polyurethane. as seen from the results for the building element flooring over pilotis a significant contribution to the final classification of the sections is the use of wood and then the ceramic and marble floor (table 8). in construction solutions beam, wall and column of reinforced concrete is observed that for all four climatic zones as the optimal solution in terms of environmental impact appears to be the one with expanded polystyrene (table 9, table 10 and table 11). the similarity between the results of these building elements can be explained by the fact that the differences between them are minor and located in small varying in the thickness of the concrete and the amount of reinforcing steel that is used for their construction. 23 table 8. optimal solutions for the building element flooring over pilotis climatic zones flooring over pilotis α with external insulation glass wool (4 cm), external coating with plasterboard and internal final covering with wood β with external insulation glass wool (5 cm), external coating with plasterboard and internal final covering with wood γ with external insulation glass wool (6 cm), external coating with plasterboard and internal final covering with wood δ with external insulation glass wool (7 cm), external coating with plasterboard and internal final covering with wood table 9. optimal solutions for the building element beam of reinforced concrete climatic zones beam of reinforced concrete α with external insulation eps (5 cm) β with external insulation eps (6 cm) γ with external insulation eps (7 cm) δ with external insulation eps (8 cm) table 10. optimal solutions for the building element wall of reinforced concrete climatic zones wall of reinforced concrete α with external insulation eps (5 cm) β with external insulation eps (6 cm) γ with external insulation eps (7 cm) δ with external insulation eps (8 cm) table 11. optimal solutions for the building element column of reinforced concrete climatic zones column of reinforced concrete α with external insulation eps (5 cm) β with external insulation eps (6 cm) γ with external insulation eps (7 cm) δ with external insulation eps (8 cm) evaluation from the results of the lca and topsis analysis it is observed that the use of wood as a material in a construction solution is suggested as an optimal solution, according to environmental impact, than materials such as concrete (in inclined roof) and ceramic or marble (in flooring over pilotis). for the horizontal construction solutions of the building envelope the use of glass wool is preferred, for the vertical construction solutions of reinforced concrete the use of eps and for the masonry in bricks the use of rock wool. the use of air gap in the construction solutions appears to have a positive contribution in their final ranking as optimal solutions. there is no diversity of the ideal construction solutions of the building elements between the four climatic zones. in the majority of the ideal solutions, as it was expected, the u value is higher than the other solutions that have a greater distance between the ideal and negative ideal solution. however this contradicts with the improved energy performance that these not ideal solutions would probably provide in the life cycle of a building and will reduce the environmental impacts in terms of energy during its life cycle. 3.2. the influence of the reduction of the u value in the energy performance of the building elements the results in this section are representative of the typical construction that was examined in this study. fig. 2. reduction of annual primary energy consumption by end use for the change of u value of the building element flooring over pilotis for the four climatic zones as seen from the results of the building element flooring over pilotis, the reduction of the u value by 0.01 w/m2.k, as calculated from the linear trends (fig. 2), leads to a decrease in annual primary energy consumption by end use 0.29333 kwh/m2 in climatic zone a, 0.31967 kwh/m2 in climatic zone b, 0.55 kwh/m2 in climatic zone γ and 0.70643 kwh/m2 in climatic zone δ. from the results of the vertical building elements (beam, wall, column of reinforced concrete and masonry in bricks), the reduction of the u value by 0.01 w/m2.k, as calculated from the linear trends (fig. 3), leads to a decrease in annual primary energy consumption by end use 0.73266 kwh/m2 in climatic zone a, 0.79297 kwh/m2 in climatic zone b, 1.3313 kwh/m2 in climatic zone γ and 1.7252 kwh/m2 in climatic zone δ. fig. 3. reduction of annual primary energy consumption by end use for the change of u value of the vertical building elements for the four climatic zones 24 from the results of building element of roof (inclined or flat) the reduction of the u value by 0.01 w/m2.k, as calculated from the linear trends (fig. 4), leads to a decrease in annual primary energy consumption by end use 0.30048 kwh/m2 in climatic zone a, 0.32333 kwh/m2 in climatic zone b, 0.50833 kwh/m2 in climatic zone γ and 0.67143 kwh/m2 in climatic zone δ. fig. 4. reduction of annual primary energy consumption by end use for the change of u value of building element of roof for the four climatic zones evaluation from the results it can be observed that in the transaction from climatic zone α to climatic zone δ for all the building elements the reduction in final annual primary energy consumption by end use increases to 100 %–150 %. this can be explained from the fact that in this transaction the heating requirements of the building increase from zone a to δ and so the influence of the u value to the reduction of energy consumption increases. 3.3. the influence of the reduction of the u value in the environmental impact of the lca and the final classification of the construction solutions the results in this section are representative of the typical construction that was examined in this study. in this analysis the quantification of the distance of the calculated u values from the maximum u values was considered in the calculation of the environmental impacts. in the building elements of masonry in bricks, flat roof, inclined roof and flooring over pilotis the ideal solution is the same with the results of the first analysis (table 5, table 6, table 7 and table 8). table 12. optimal solutions for the building element beam of reinforced concrete climatic zones beam of reinforced concrete α with external insulation polyurethane (4 cm) β with external insulation polyurethane (5 cm) γ with external insulation eps (7 cm) δ with external insulation eps (8 cm) in construction solutions beam, wall and column of reinforced concrete is observed that in climatic zone a and b the optimal solution in terms of environmental impact appears to be the one with polyurethane (table 12, table 13 and table 14). in climatic zone γ and δ the optimal solution appears to be expanded polystyrene (eps). table 13. optimal solutions for the building element wall of reinforced concrete climatic zones wall of reinforced concrete α with external insulation polyurethane (5 cm) β with external insulation polyurethane (6 cm) γ with external insulation eps (7 cm) δ with external insulation eps (8 cm) table 14. optimal solutions for the building element column of reinforced concrete climatic zones column of reinforced concrete α with external insulation polyurethane (4 cm) β with external insulation polyurethane (5 cm) γ with external insulation eps (7 cm) δ with external insulation eps (8 cm) evaluation from this analysis is observed that there is more diversity in the optimal solutions between the four climatic zones. the use of wood instead of materials like concrete, ceramics and marble appears to be a better solution as it also was in the first analysis. in construction solutions that only differ in the type of the insulating material, the one with the lower u value appears to be the optimal solution. the use of rock wool and air gap in masonry in bricks and glass wool in flat roof and flooring over pilotis appear to be optimal solutions such as in the first lca and topsis analysis. 4. discussion in this study the lca takes into account quantities of materials that are used for the construction of a building element. as a result from the first and second lca and topsis analysis, an important issue that determines an ideal construction solution is the number of layers and the type of materials that it consists of, as they affect the quantities and the environmental impacts of its life cycle. a second important issue is that the u value affects the energy performance of a building and the energy consumption by end use. it is a parameter that should be considered when a selection of a construction choice depends both on the environmental impacts and its energy performance during its life cycle. when the construction solutions have the same number of layers and materials and they only differ in the type of the insulating material is suggested that the preferable solution is the one with the lower u value. the use of wood as material is an optimal solution, when the criteria for this choice are environmental impacts, as in some categories of environmental impacts it has nearly zero or maybe negative values. 25 the use of air gap in construction is suggested either if the air layer is isolated in the middle of the construction or in a ventilated solution because it improves the energy performance of a building element by decreasing the u value without increasing the environmental impacts. 5. conclusions continuous efforts in europe aim to reduce the environmental impact from the energy consumption and to decrease the use of non renewable sources of energy. this occurs from the fact that in a life cycle of buildings the majority of environmental impacts come from the energy consumption from the use stage of the building. the environmental impact from the materials and the other stages amount a small percentage of the total environmental impact of its life cycle. however even it is a small percentage it is something that cannot be ignored. all these interventions for upgrading the energy performance of a building should be examined for their environmental impacts. also in the choice of the materials and the construction solutions for upgrading an existing building or designing a new one, should be taken into account the environmental impact during their whole life cycle and not only in the operation stage. furthermore in the choice of an insulating material or a construction solution that affects the energy performance of a building should be considered not only the u value that it provides but also if the benefit from this choice overrides the environmental impacts during its life cycle. this study shows the optimal construction solutions of building elements in residential buildings in greece and provides suggestions for the materials that should be used. its aim is to provide a helpful guide to the designers in order to choose a construction solution, depending on the climatic zone that is going to be constructed, considering its energy performance and its environmental impact during its life cycle. in conclusion this study shows that the influence of the u value in the energy performance of the building elements and the choice of the insulating material are significant factors to the environmental impacts of their life cycle. for the masonry in bricks the use of rock wool with the use of air gap is suggested rather than eps or xps in all climatic zones. in the construction solution of flat roof the use of xps appears to be an optimal solution in all climatic zones rather than polyurethane. for the inclined roof the use of wood and glass wool appear to be optimal solutions rather than concrete and eps in all climatic zones. in the construction solution of flooring over pilotis the use of glass wool is suggested rather than xps in all climatic zones. for the vertical construction solutions of reinforced concrete (beam, column and wall) the use of polyurethane in climatic zones a and b is suggested rather than eps and xps. in climatic zones γ and δ the use of eps appear to be an optimal solution rather than polyurethane and xps. acknowledgment this study was carried out for a diploma thesis in the msc program “environmental protection and sustainable development” of the department of civil engineering of aristotle university of thessaloniki. this paper was completed as a part of this msc program and co-financed by the act “scholarships program ssf (state scholarships foundation/iky) with an individualized assessment process of the academic year 2012-2013” from resources of the operational program “education and lifelong learning”, of the european social fund (esf) and the nsrf (20072013). references cml, 2013. available at: http://cml.leiden.edu/software/datacmlia.html (accessed 15 august 2013). eurostat, 2013. available at: epp.eurostat.ec.europa.eu/: http://epp. eurostat.ec.europa.eu/tgm/table.do?tab=table&init=1&plug in=1&language=en&pcode=ten00086 (accessed 25 august 2013). hellenic statistical authority (el.stat.), 2013. available at: http://www.statistics.gr/portal/page/portal/esye/pagethemes?p_param=a1302 (accessed 23 june 2013). iso13790, 2008. energy performance of buildings calculation of energy use for space heating and cooling. κενακ, 2010. αριθ. δ6/β/οικ. 5825 ΄εγκριση κανονισμού ενεργειακής απόδοσης κτιρίων εφημερίς της κυβερνήσεως της ελληνικής δημοκρατίας, 5333-5356, [regulation of energy performance in buildings]. preconsultants, 2008. available at: http://www.pre-sustainability. com/simapro-7-database-and-methods-library (accessed 15 august 2013). αραϊλόπουλος, α., χαστάς, π. (2009). ανάλυση κύκλου ζωής στα κτίρια με εφαρμογή του λογισμικού simapro και της μεθόδου eco-indicator 99. πολυτεχνική σχολή α.π.θ, πολιτικών μηχανικών, θεσσαλονίκη [arailopoulos a., chastas p. life cycle assessment in buildings with the use of the software simapro and the method eco-indicator 99]. τοτεε 20701−1, 2010. αναλυτικές εθνικές προδιαγραφές παραμέτρων για τον υπολογισμό της ενεργειακής απόδοσης κτιρίων και την έκδοση του πιστοποιητικού ενεργειακής απόδοσης. εφημερίς της κυβερνήσεως της ελληνικής δημοκρατίας, vol. 1387, 21435-21442. [technical instructions of the technical chamber of greecedetailed national standards and parameters for calculating the energy performance of buildings and issuing energy performance certificate]. τοτεε 20701−2, 2010. θερμοφυσικές ιδιότητες δομικών υλικών και έλεγχος της θερμομονωτικής επάρκειας των κτιρίων. εφημερίς της κυβερνήσεως της ελληνικής δημοκρατίας, vol. 1387, 21435-21442. [technical instructions of the technical chamber of greecethermophysical properties of building materials and control of thermal insulation efficiency of buildings]. τοτεε 20701−3, 2010. κλιματικά δεδομένα ελληνικών περιοχών. εφημερίς της κυβερνήσεως της ελληνικής δημοκρατίας vol. 1387, 21435-21442. [technical instructions of the technical chamber of greece climate data of greek regions]. received 2013 12 16 accepted after revision 2014 02 08 26 dimitrios bikas – professor, director laboratory of building construction and building physics, vice chairman of the dept. of civil engineering. main research area: building construction, building physics, energy efficiency of buildings, sustainable building. address: aristotle university of thessaloniki, dept. of civil engineering, laboratory of building construction and building physics, 54124 thessaloniki, greece. tel.: +30 2310 995763, +30 6972096311 e-mail: bikasd@civil.auth.gr panagiotis chastas – civil engineer and msc “environmental protection and sustainable development” graduate, dept. of civil engineering of aristotle university of thessaloniki (auth). main research area: life cycle analysis and energy performance in residential buildings. address: aristotle university of thessaloniki, dept. of civil engineering, laboratory of building construction and building physics, 54124 thessaloniki, greece. tel.: +30 6976500057 e-mail: pchastas@civil.auth.gr journal of sustainable architecture and civil engineering 2015/1/10 58 jsace 1/10 received 2014/06/30 accepted after revision 2015/02/12 journal of sustainable architecture and civil engineering vol. 1 / no. 10 / 2015 pp. 58-65 doi 10.5755/j01.sace.10.1.7479 © kaunas university of technology usage of the wind energy for heating of the energy-efficient buildings: analysis of possibilities *corresponding author: tadas.zdankus@ktu.lt usage of the wind energy for heating of the energyefficient buildings: analysis of possibilities http://dx.doi.org/10.5755/j01.sace.10.1.7479 jurgita černeckienė, tadas ždankus* kaunas university of technology, faculty of civil engineering and architecture studentu st. 48, lt-51367 kaunas, lithuania the paper analyzes and compares the energy demand for heating purpose of new buildings with different energy perfomance rates. article studies global renewable energy sources innovations, statistics and scientific and engineering experience to ensure the building’s thermal energy needs, produced by transforming wind energy. distribution of the potential of one renewable source – wind energy – during the year is similar to the energy necessary for the building heating, thus production of the heating energy from mechanic energy of the wind is chosen for further scientific investigations. wind power plant, generating 2 kw of heat power, installed as a heating source for the analysed individual house, can cover from 40 to 76% annual heat needs of the building, subject to its energy-efficiency class, respectively 1.5 kw – from 31 to 68%, 1 kw – from 22 to 53%. keywords: energy efficiency, energy conversion, heating, wind energy. there are no doubts that the energy saving, its efficient usage and searches of the new methods of the energy production are very topical by many aspects. the burning of fossil fuels influence the greenhouse gas emissions (co 2 , ch 4 , n 2 o, etc..), that gives impact on the planet’s atmospheric composition. in order to solve this problem, the global community adopted united nation’s framework convention on climate change, which commits to reducing greenhouse gas emissions. eu countries have set the goals that are easy to remember in this area: by 2020 – 20% reduction in energy consumption, 20% reduction in greenhouse gases discharged to the environment and to produce 20% of all necessary energy from the renewable sources (energy efficiency directive 2012/27/eu). many countries shall find that besides the above mentioned arguments the economic aspect is topical as well – i.e., in the countries, where the residents spend proportionally bigger part of the family budget for the accommodation heating (eg, in the 2013 lithuanian ministry of environment ordered a survey where 35% of lithuania’s population has indicated that at the end of the last heating season their home heating costs accounted for 16-30% of monthly income), and in the countries that spend significant part of the budget for the fuel import, energy saving is the matterof-course by the extent of the country and the separate households. in comparison in 2010, for introduction 59 journal of sustainable architecture and civil engineering 2015/1/10 gas, electricity and oil, lithuania paid about 2,3 bill. eur per year, while the whole lithuanian state budget amounted 5,2 bill. eur. building heating in lithuania consumes 23% of the total consumption of primary energy (lietuvos šilumos tiekėjų asociacija, 2010). as the consumed part is significant, big attention is paid to the designing and construction of the new energy-efficient buildings. at the moment, str 2.05.01:2013 “designing of the energy-efficiency of the buildings” approved in lithuania shall determine the requirements for energy-efficiency classes of all new buildings. class of the energy-efficiency – building evaluation, including many aspects: _ thermal characteristics of the building partitions, _ building tightness that is the characteristic of the construction work quality very often, _ usage efficiency of the non-renewable (primary – oil, natural gas, coal, peat) and renewable (wind, solar, aerothermal, geothermal, hydrothermal and ocean energy, hydropower, biomass, landfill gas, sewage treatment plant gas and biogas) energy sources that is related to the systems installed in the building, their automatic adjustment and energy saving at the same time. _ this article shall analyse the opportunities to produce a part or all necessary heating energy in the building using the renewable sources in more detail. very often this topic is evaluated sceptically, because of the thinking that energy needs of the buildings are conditionally big, and potential of the renewable sources is small. therefore, analysis of the heating needs and possibilities meeting them using wind energy should decrease scepticism and form further tasks at issue, in order to develop implementation of the alternative energy sources both, in the sense of quantity and quality. 120 m2 living house designed according to the principles of the energy-efficiency has been chosen for the analysis (fig. 1). building has two floors; transparent partitions (windows and doors) shall make 19% of the area of all vertical partitions, and 64% of them is oriented to the south. methods fig. 1 building visualization – upper: south western façade; lower: north eastern facade (source www.haus.lt, project author arch. a. zaniauskas) a few calculation variants have been made – when the building partitions meet requirements of the energyefficiency class “b”, “a”, “a+” and “a++”. designed heat needs for the building heating have been calculated by evaluating the heat losses through the building partitions, heat need for the building mechanic ventilation and losses due to the outside air infiltration. in addition, the inflows from the people, electric lighting system and home electric appliances and due to the solar radiation have been evaluated. in order to meet the air quality conditions regulated by the hygiene standards, the calculations shall analyse the building that has the mechanic ventilation system installed, although, according to the valid construction technical regulations, such system is not obligatory to all variants of the energy-efficiency classes analysed. journal of sustainable architecture and civil engineering 2015/1/10 60 it is considered that average temperature in the rooms is +20°c (during working days for 9 hours and during weekends for 6 hours per day – +18°c, and during working days for 15 hours and during weekends for 18 hours per day – +21°c). calculations have been made according to the climatology data of kaunas city. calculation has been made according to str 2.09.04:2008 “capacity of the building heating system. heat need for heating”. results of the calculations shall be provided in the table 1–3. in this case, losses due to the external door opening/closing have not been evaluated, although, there is no doubt that such losses are conditioned by the building exploitation. it is more rational applying the passive solutions for compensation of the heat losses through the door – hood without results table 1 heat losses through the building partitions q en , kwh energy-efficiency class of the building month b a a+ a++ january 3204 1574 1333 1130 february 2827 1375 1157 978 march 2656 1284 1077 909 april 1859 861 703 584 may 1119 466 355 281 june 678 230 146 100 july 546 158 82 44 august 590 180 101 60 september 1084 443 333 261 october 1691 766 618 509 november 2262 1070 887 743 december 2840 1379 1160 980 in total: 21356 9786 7953 6578 table 2 heat losses due to the mechanical ventilation (including infiltration of the outside air) q v , kwh class of the building energy-efficiency/coefficient of the efficiency of the heat recovery equipment month b/0,65 a/0,65 a+/0,8 a++/0,9 january 1222 1222 1003 858 february 1064 1064 874 747 march 989 989 812 694 april 666 666 547 467 may 368 368 302 258 june 196 196 161 138 july 150 150 123 105 august 174 174 143 122 september 380 380 312 266 october 625 625 513 439 november 854 854 701 599 december 1081 1081 888 759 in total: 7769 7769 6380 5453 automatic quantitative regulation, i.e., such system that will not react to the cooled air of the premises due to the opened door and will not increase the amount of heat supplied to the room. when the door is opened, hood temperature for the specific area shall decrease, but this does not condition the general comfort of the building residents significantly. after comparison of the building heat losses through the partitions and losses due to the ventilation system, the tendency that when energy-efficiency of the building increases, the percent distribution changes and is almost equal to the buildings having the biggest energy-efficiency (a++ class) (6578kwh/5453kwh – 55%/45%). thus, we can make the implication that bigger attention will be paid to the development of the ventilation system equipment of the building and management and automation of such systems in the future. heat inflow to the building due to the solar radiation can be analysed in more detail, as this free heat shall make the biggest part of the internal inflows – 65-77% (for the analysed building). in order to design energy-efficient buildings, special attention shall be paid to the selection of the window width 61 journal of sustainable architecture and civil engineering 2015/1/10 and glass pack construction. there is a need to decide objectively, what window size and construction are the most rational, as the heat energy through the windows is lost and got due to the solar radiation. calculations that are used when increasing the window width in the facades oriented to the different world sides shall be provided in the tables 4-8 (decreasing area of the outside walls appropriately). months of heating season (october-april) shall be chosen for the analysis, i.e., when the outside temperature is less or equal to +10°c and the internal building releases do not compensate the heat losses. when performing the calculation, difference of the heat transfer coefficient of the window u w and wall, coefficient of the skip of the aggregate solar energy g and coefficient f c allowed evaluating the effect of the solar protection means. detail analysis has revealed that in some cases the building project can be changed by increasing the window areas table 3 heat inflow to the building from the people, lighting and home electric appliances q ig , kwh month for all energyefficiency classes january 202 february 182 march 199 april 190 may 188 june 182 july 188 august 188 september 190 october 199 november 195 december 202 in total: 2307 in such facades, where the solar radiation intensity is the biggest. in the buildings that coefficients of the heat transfer of the walls and windows shall meet the standard values of a+ and a++ classes of the buildings, it is rational to maximally increase the area of the windows in the southern facade, as the windows oriented to the south during heating season shall pass the heat energy to the rooms more due to the effect of the solar radiation, compared to the heat losses (numbers in green boxes indicate reasonable solution, in yellow – close to reasonable solution result). southern facade of table 4 part of heat losses through the windows covered by the heating system (+) and solar radiation (-) in the building of energy-efficiency class b, % (uw 1.6, g 0.53, fc – 0.8) table 5 part of heat losses through the windows covered by the heating system (+) and solar radiation (-) in the building of energy-efficiency class a, % (uw 1, g 0.48, fc – 0.8) month n e s w january 88 87 73 87 february 74 71 51 70 march 49 35 2 33 april 22 -10 -34 -5 october 64 51 11 53 november 89 87 72 87 december 92 91 79 91 in total: 71 64 42 64 month n e s w january 82 81 60 80 february 61 58 28 56 march 25 4 -45 1 april -15 -62 -98 -55 october 48 28 -30 31 november 83 81 59 81 december 88 87 69 86 in total: 58 46 15 47 the analysed building has been used effectively to this point, but when transferring part of the windows designed in the north side to the western and eastern facade, characteristics of the premises’ lighting shall not decrease and the heat inflows would be bigger. in the buildings, where coefficients of the heat transfer meet standard values of the buildings of class a, area of the windows should be increased, if it is possible decreasing area of the window with the solar protection means or not using such means during the heating season (table 8). aim of the calculations provided above – to optimise the architectural solutions of the building and to determine needs of the heating system (fig. 2) for the energy-efficient journal of sustainable architecture and civil engineering 2015/1/10 62 buildings and rational capacity of the alternative heat source of such buildings. in addition, calculations shall allow checking, if the wind energy can guarantee the heat quantity (or its part) necessary for the building heating. calculations performed shall indicate that average need of the moment energy for heating is from 5 kw (for typical family house of energy-efficiency class b) to approx. 2 kw (for typical family house of energy-efficiency class a++). in addition, due to variability of the wind energy (as any other alternative energy source), a possibility to produce only part of energy necessary for the building heating by transforming the wind energy shall be analysed, as in any case the source guaranteeing the appropriate heating energy supply should be installed in the building in parallel (biofuel, gas fuel boiler; unit of the centralized heating networks or electric heating system, using electric power from the cen tralized networks). table 6 part of heat losses through the windows covered by the heating system (+) and solar radiation (-) in the building of energy-efficiency class a+, % (uw 0.85, g 0.48, fc – 0.8) month n e s w january 79 77 52 77 february 54 50 15 48 march 11 -14 -72 -17 april -36 -93 -135 -85 october 38 14 -55 18 november 80 77 51 77 december 85 84 63 84 in total: 50 36 -1 36 table 7 part of heat losses through the windows covered by the heating system (+) and solar radiation (-) in the building of energy-efficiency class a++, % (uw 0.7, g 0.48, fc – 0.8) month n e s w january 74 72 41 71 february 43 38 -5 35 march -10 -40 -112 -45 april -68 -138 -190 -128 october 23 -6 -91 -1 november 76 72 40 72 december 82 80 55 80 in total: 38 21 -25 22 table 8 part of heat losses through the windows covered by the heating system (+) and solar radiation (-) in the building of energy-efficiency class a, % (uw 1, g 0.48, fc – 1.0) month n e s w january 77 76 50 75 february 52 47 10 45 march 7 -19 -81 -23 april -43 -103 -147 -94 october 35 9 -63 14 november 79 76 49 76 december 85 83 62 83 in total: 47 33 -6 33 if the wind power plant, generating 2 kw of heat power, is installed for the analysed case, it would be possible to cover from 40 to 76% annual heat needs of the building, subject to its energyefficiency class, respectively 1.5 kw – from 31 to 68%, 1 kw – from 22 to 53%. wind energy application for the building heating has been chosen due to a few reasons: 1 distribution of the wind energy potential during a year is closer to the heating needs of the building, compared to the solar radiation energy used widely – it is due to the fact that wind power is directly dependent on the wind velocity and air density (adomavičius v., 2013) – average wind velocity is bigger in winter than in summer in lithuania (adomavičius v., 2011) (fig. 3) and density of the cold air is bigger than warm air; 2 much bigger availability of the wind energy for the individual houses, compared to the hydro-energy; 63 journal of sustainable architecture and civil engineering 2015/1/10 3 during exploitation wind energy does not release pollution (f.e. like during combustion of biofuel) to the environment. fig. 3 shall present average values of the wind speed (galvonaitė a., 2013), they cannot be used when making implications on the wind energy potential in the specific land plot. for this purpose, annual measurements of the wind speed in the land plot should be performed (marčiukaitis m., 2009). theoretically, it is possible to model speeds of the wind in the specific land plot and surrounding territories, but network of the stations for the wind speed measurement is conditionally small (in lithuania wind speed is being measured in 18 stations in the height of 10 m) and work extent of such modelling would be unjustified big. in order to perform primary evaluation of the system “wind power plant – heat generator”, the calculations have been performed; they have revealed that in case of average wind speed of 4 m/s (for example, it is the average annual wind speed in lithuania), in order to generate 1 kw of heating energy, three-vane wind turbine with horizontal axis of diameter 8.22 m that power factor is cp=0.49 shall be needed (kytra s., 2006). the analyzed living house, which is equipped with wind turbine of 1 kw power and which can manufactured from 3433 kwh (a + + energy efficiency class of the building) to 4241 kwh (“b” energy fig. 2 average instantaneous thermal power demand for heating of the analysed buildingof different energy-efficiency classes during the year a++ class a+ class fig. 3 distribution of the average wind velocity during a year according to the data of 1981-2010 journal of sustainable architecture and civil engineering 2015/1/10 64 efficiency class of the building) thermal energy, protects the atmosphere of not throwing in the environment up to 856 kg of greenhouse co 2 gas (as compared to natural gas combustion for heating), which is the co 2 “footprint” equivalent to about 4000 km journey by car. co2 treatment is relevant because it accounts for about 95% of the total greenhouse gas structure (konstantinavičiūtė i., 2012). discussion principles of the heat production directly from the mechanic wind energy have been already described in the previous works of the engineers and scientists. in most cases equipment of such type is based on the usage of the volume hydraulic machines (pumps), where the kinetic energy of the wind wheel axis is transferred to the potential fluid energy, and due to the artificial obstacle and friction to it the fluid potential energy is transferred to the heat energy (maegaard p., 2013). in 1960 v. v. blasutta and j. f. hedge (“fluid pressure energy translating device”, usa) and in 1981 – w.j. grenier (“fluid friction heater”, usa) have described and patented the device of such type. in 1983 j. e. knecht (“wind driven heating system”, usa) and in 1986 h. w. haslach (“wind turbine heat generating apparatus”, usa) have patented devices of the analogous type that suggested using heat generated due to the fluid friction and have used the wind wheel as the source of the primary energy. we can state that such interest in the alternative energy in the eight-ninth decade of xx century could be conditioned by the world oil crisis of 1973, when big part of people has felt significant shortage of the fossil fuel. in addition, input of the danish scientists and technical enthusiasts to the development of the wind power plants producing heat can be noticed. nowadays and in the eight decade of the last century denmark was the leader in the area of the wind energy usage. in 1973 engineers s. s. kofoed and r. matzen from the institute of the agriculture engineering (taastrup, denmark) has created, tested and developed the wind power plant “mark” (version “mark i” and “mark ii”), producing heat energy from the wind mechanic energy. later, h. h. ekner has created the wind power plant “calorius” that has gained an attention from the scientists as well – capacity and noise level tests have been performed for the power plant of such construction and in 1993–2000 danish company “westrup” has installed and started 34 power plants “calorius” (according to 2012 data, 17 of them are still used). although a lot of scientists and engineers see a lot of benefits of the wind power plants producing heat, but power plants of such type has not been used widely in practice. we can make assumptions that there was a lack of subsidies from the national funds, provided to the production of the electricity from the wind energy. in lithuania possibilities to use the wind energy have been explored in more detail and various publications prepared in a. stulginskis university (former university of agriculture of lithuania). firstly, instalment of the equipment for using the wind energy has been topical in the localities distant from the centralized networks, thus the scientists of this university have paid bigger attention to this topic. in 2001 in the institute of the agriculture engineering of the lithuanian agriculture university a. gulbinas has prepared and defended doctor’s dissertation on the topic “investigation of the effective usage of the wind energy equipment in the agriculture“. in addition, in 2011 a. kavolynas has defended the doctor’s dissertation in a. stulginskis university on the topic “solar and wind energy usage for meeting the heat needs of the buildings in the rural localities”, however, in this work the author has paid more attention to the investigation of usage of the solar energy and its accumulation, and the topic of wind energy has been analysed according to the works of other authors. a lot of international organizations work in the area of the wind energy usage – global wind energy council (gwec) represents over 70 countries; european wind energy association (ewea), established in 1982 in belgium and having 600 members from almost 60 countries; world wind energy association (wwea) – established in germany and having 95 members. lithuanian wind energy association (lwea), established in 2005, is the member of the international organizations as well. lwea pays the biggest attention to the development of the electricity production in the wind power stations. 65 journal of sustainable architecture and civil engineering 2015/1/10 distribution of the potential of one renewable source – wind energy – during the year is similar to the energy necessary for the building heating, thus production of the heating energy from mechanic energy of the wind shall be chosen for further scientific investigations. wind power plant, generating 2 kw of heat power, installed as a heating source for the analysed individual house, can cover from 40 to 76% annual heat needs of the building, subject to its energyefficiency class, respectively 1.5 kw – from 31 to 68%, 1 kw – from 22 to 53%. the heat power of 1 kw can be performed in the system “wind power plant – heat generator” with threevane wind turbine with horizontal axis of diameter 8.22 m in case of average wind speed of 4 m/s. the following area still lacks unbiased quantitative evaluation of the effectiveness, so this fact may restrict implementation of such systems practically. conclusions referencesadomavičius v. 2013. mažosios atsinaujinančiųjų išteklių energijos sistemos. kaunas: technologija, 288 p. http://dx.doi.org/10.5755/e01.9786090209448 adomavičius v. 2011. atsinaujinančiųjų išteklių energiją naudojančių mažos galios sistemų tyrimas (daktaro disertacija). kaunas. energy efficiency directive 2012/27/eu. galvonaitė a. et al. 2013. vidutinių klimatinių rodiklių reikšmės lietuvoje 1981-2010 m. / climate average for lithuania 1981-2010, lietuvos hidrometeorologijos tarnybos prie aplinkos ministerijos klimatologijos skyrius / climatology division at lithuanian hydrometeorological service under the ministry of environment. gulbinas a. 2001. vėjo energijos įrenginių naudojimo efektyvumo žemės ūkyje tyrimas (daktaro disertacija). raudondvaris. jakštas a. 2000. energijos transformavimo mašinos. vilnius: technika, 144 p. kavolynas a. 2011. saulės ir vėjo energijos naudojimas pastatų kaimo vietovėse šilumos poreikiams tenkinti (daktaro disertacija). akademija. kytra s. 2006. atsinaujinantys energijos šaltiniai. kaunas: technologija, 301 p. konstantinavičiūtė i. 2012. šiltnamio efektą sukeliančių dujų nacionalinių emisijų rodiklių energetikos sektoriuje vertinimas, lietuvos energetikos institutas. lietuvos šilumos tiekėjų asociacija. 2010 m. pranešimas: „lietuvos šilumos ūkis: esama padėtis ir kliūtys vystymuisi“ [lithuanian district heating association. 2010. report: „lithuania heat sector: current situation and the obstacles to development“], available at: http://www.lsta.lt/files/leidiniai/pranesimas_lt_ 100920.pdf (accessed 28 may 2014). maegaard p. et al. 2013. wind power for the world: the rise of modern wind energy. singapore, pan stanford publishing pte. ltd., 627 p. marčiukaitis m. 2009. vėjo energijos tyrimai, modeliavimas ir prognozė (daktaro disertacija). kaunas. str 2.05.01:2013 “pastatų energinio naudingumo projektavimas“. str 2.09.04:2008 „pastato šildymo sistemos galia. šilumos poreikis šildymui“. jurgita černeckienė phd student, assistant kaunas university of technology, department of building energy systems main research area heating, energy efficiency address studentu st. 48, lt-51367 kaunas, lithuania tel. +37061531533 e-mail: jurgita.cerneckiene@ktu.lt tadas ždankus professor kaunas university of technology, department of building energy systems main research area fluid mechanics address studentu st. 48, lt-51367 kaunas, lithuania tel. +37037300492 e-mail: tadas.zdankus@ktu.lt about the authors 50 darnioji architektūra ir statyba 2014. no. 1(6) journal of sustainable architecture and civil engineering issn 2029–9990 analysis of crack width calculation of steel fibre and ordinary reinforced concrete flexural members šarūnas kelpša*, mindaugas augonis, mindaugas daukšys, algirdas augonis kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367 kaunas, lithuania. *corresponding author: sarunas.kelpsa@gmail.com http://dx.doi.org/10.5755/j01.sace.6.1.6336 it is known that steel fibre can reduce the crack width of reinforced concrete flexural members however generally accepted crack width calculation method does not exist yet. the residual tensile strength which is used for crack width calculations should be obtained from tests. three crack width calculation methods of steel fibre and ordinary reinforced concrete flexural members are discussed in this paper. all these methods have been derived using eurocode 2 provisions, which are intended to the members without the fibre. experimental cracking results of small cross section flexural members reinforced with steel fibre and ordinary reinforcement are also discussed. a scatter of the residual tensile strength which is obtained from three point bending test and its influence to the crack width is also reviewed briefly. calculated crack widths are compared to the experimental results. it is determined that due to lack of the specimens the large deviations of residual flexural tensile strength can be obtained and it can cause the significant errors of calculated crack widths. keywords: steel fibre, residual tensile strength, crack width, cmod, sfrc. 1. introduction the application of steel fibre has been investigated over the past few decades. today the steel fibre is commonly used in slabs on grade and sprayed concrete although other application areas exist. the wider practice of the fibre is still restricted because there is no generally accepted design method. also, the application of the steel fibre in structural design is limited due to the efficiency of steel fibre which has to be established from tests every time (jansson 2007; ulbinas, 2012). depending on fibre content and its parameters the steel fibre can change properties of concrete slightly: compressive, tensile strength and modulus of elasticity. however, the steel fibre changes a nature of concrete collapse most highly: steel fibres enhance the post-cracking properties of concrete and the collapse becomes more ductile. steel fibre reinforced concrete (sfrc) has load bearing capacity even after cracking. depending on the fibre parameters and the fibre content the post cracking strength can be higher or lower than the tensile (peak) strength of sfrc (naaman, 2003; ulbinas, 2012; vandewalle, 2007). after the cracking of steel fibre and ordinary reinforced concrete members, the steel fibre can transfer tensile stresses across the cracks and so it leads to a reduction of the crack widths. when the residual tensile strength of sfrc is higher than the tensile strength, then strain/deflection hardening post cracking behaviour is achieved. in this case, more cracks will open if the load is still increasing after the cracking.. whereas when the residual tensile strength is lower than the tensile strength of sfrc, then strain/ deflection softening behaviour is achieved and no more cracks will open. depending on stress-strain distribution in the section, the strain hardening is achieved using larger amount of the fibre than for the case of deflection hardening behaviour (jansson, 2007; jansson et. al., 2008; naaman, 2003). in order to determine material properties of the sfrc some different tests methods were proposed: three and four point bending tests, round and square panel tests, wedge splitting tests and uniaxial tension tests. it is established, that the size of specimens determines a scatter of results – as the cracked area is bigger as the scatter of the results is lower. although the residual tensile stress (axial postcracking strength) of sfrc is determined indirectly and with the large scatter of the results, however the three point bending test method is common, because of simplicity of it (jansson, 2007; jansson et. al., 2008; parmentier et. al., 2008; vandewalle et. al., 2008). the composite reinforcement (steel fibre and ordinary reinforcement) allows us to reduce the width of the cracks and to enhance stiffness of the flexural members. (ulbinas, et. al. 2009). rilem tc 162-tdf (hereafter rilem) has published the recommendations in 2003 (rilem tc 16251 tdf 2003) and there is offered the crack width calculation method of steel fibre and ordinary reinforced concrete flexural members. in order to get a better agreement between tests and calculation results other scientists have analysed this method and made their corrections then (jansson et. al., 2010; löfgren, 2007). the estimation of cracking moment and three crack width calculation methods of steel fibre and ordinary reinforced concrete flexural members are discussed in this article. in order to examine calculation results the experimental program was performed. the residual flexural tensile strength (fr,1) of sfrc, compressive and tensile strengths of concrete and the sfrc as well as modulus of elasticity of the concrete were measured during these tests. the crack widths of the small cross section flexural concrete members reinforced with steel fibre and ordinary reinforcement were also measured. the experimental crack widths of full scale beams reinforced with steel fibre and ordinary reinforcement were taken from the reference (ulbinas 2012). comprehensive analysis and the comparison of calculated crack widths and the experimental results are also executed in this paper. 2. methods 2.1. verification of crack opening a cross section of sfrc member is uncracked until tensile stress does not exceed the critical value. theretofore by provisions of ec2 the full section is assumed to be elastic (fig. 1). steel fibre can change the tensile strength of concrete depending on fibre parameters. however in the calculations of the crack width opening of sfrc members it can be assumed approximately that the tensile strength of sfrc is equal to tensile strength of concrete (jansson 2007). in more details, the tensile strength of sfrc is studied in the other publications – naaman 2003, etc. in this case a cracking moment is calculated according to a formula (1): reinforcement were also measured. the experimental crack widths of full scale beams reinforced with steel fibre and ordinary reinforcement were taken from the reference (ulbinas 2012). comprehensive analysis and the comparison of calculated crack widths and the experimental results are also executed in this paper. 2. methods 2.1. verification of crack opening a cross section of sfrc member is uncracked until tensile stress does not exceed the critical value. theretofore by provisions of ec2 the full section is assumed to be elastic (fig. 1). steel fibre can change the tensile strength of concrete depending on fibre parameters. however in the calculations of the crack width opening of sfrc members it can be assumed approximately that the tensile strength of sfrc is equal to tensile strength of concrete (jansson 2007). in more details, the tensile strength of sfrc is studied in the other publications – naaman 2003, etc. in this case a cracking moment is calculated according to a formula (1): elctmcrc wfm ⋅= , and strain distribution given in fig. 1 (singly reinforced section). fig. 1. stress and strain distribution in uncracked section of sfrc flexural member the stress and strain distribution is analogical in doubly reinforced section, but the top reinforcement should be considered in that case. 2.2.crack width calculation method proposed by rilem tc 162-tdf for the crack width calculation of steel fibre and ordinary reinforced concrete members rilem has proposed an application of crack width calculation method given in old env 1992-1-1:1991. the calculation method of env 1992-1-1:1991 was supplemented marginally. the coefficient which reduces average crack spacing was involved. this coefficient depends on parameters of the steel fibre. furthermore, the stress in tensile reinforcement (σ s and σ sr ) should be calculated considering that the steel fibres, which cross the crack, take over the residual tensile stresses (σ fb ) uniformly through the all crack height. the stress and strain distribution in the cracked section is given in fig. 2. in this case, the residual tensile stress is taken over in a part of the crack height. such stress distribution could be obtained when the flexural member has a notch. here a fb is the section height where the steel fibre does not take over the residual tensile stress. in other cases, when there is no factors, which can reduce the area of the residual tensile stress, then a fb = 0. fig. 2. stress and strain distribution in cracked section of sfrc flexural member the method proposed by rilem indicates that the residual tensile stress should be calculated according to the formula (2) (rilem tc 162-tdf 2003): 1, 45.0 rmfb f=σ , (2) where: f rm,1 – the mean value of the flexural residual tensile strength, obtained by three–point bending test method. in more details this test are discussed in section 2.4. according to the above discussed method the crack width is calculated by the formula (3): smrmk sw εβ = , (3) where: w k – the final crack width, s rm – the average final crack spacing, ε sm – the mean strain in the tension reinforcement, β – coefficient relating the average crack width with the design value (for load induced cracking β = 1.7). the mean strain in the tension reinforcement ε sm is calculated according to the formula (4): ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 21 1 s sr s s sm e σ σ ββ σ ε , (4) where: σ s – the stress in the tensile reinforcement calculated on the basis of a cracked section (fig. 2), σ sr – the stress in the tensile reinforcement calculated on the basis of a cracked section under loading conditions causing first cracking (fig. 2), β 1 – coefficient which takes account of the bond properties of the bars, β 2 – coefficient which takes account of the duration of the loading or of repeated loading. the stresses in the tension reinforcement σ s1 and σ sr1 can be obtained from the system of equilibrium equations of forces and moments. this system for singly reinforced sfrc flexural members (when a fb = 0) is given in the equation (5): (1) where: fctm (fctm,fl) – mean value of axial (flexural) tensile strength of concrete (sfrc); wel – elastic resisting moment of reinforced concrete member. in analysis of the crack width which is given in section 3, the cracking moment is calculated according to a stress and strain distribution given in fig. 1 (singly reinforced section). fig. 1. stress and strain distribution in uncracked section of sfrc flexural member the stress and strain distribution is analogical in doubly reinforced section, but the top reinforcement should be considered in that case. 2.2. crack width calculation method proposed by rilem tc 162-tdf for the crack width calculation of steel fibre and ordinary reinforced concrete members rilem has proposed an application of crack width calculation method given in old env 1992-1-1:1991. the calculation method of env 1992-1-1:1991 was supplemented marginally. the coefficient which reduces average crack spacing was involved. this coefficient depends on parameters of the steel fibre. furthermore, the stress in tensile reinforcement (σs and σsr) should be calculated considering that the steel fibres, which cross the crack, take over the residual tensile stresses (σfb) uniformly through the all crack height. the stress and strain distribution in the cracked section is given in fig. 2. in this case, the residual tensile stress is taken over in a part of the crack height. such stress distribution could be obtained when the flexural member has a notch. here afb is the section height where the steel fibre does not take over the residual tensile stress. in other cases, when there is no factors, which can reduce the area of the residual tensile stress, then afb = 0. fig. 2. stress and strain distribution in cracked section of sfrc flexural member the method proposed by rilem indicates that the residual tensile stress should be calculated according to the formula (2) (rilem tc 162-tdf 2003): reinforcement were also measured. the experimental crack widths of full scale beams reinforced with steel fibre and ordinary reinforcement were taken from the reference (ulbinas 2012). comprehensive analysis and the comparison of calculated crack widths and the experimental results are also executed in this paper. 2. methods 2.1. verification of crack opening a cross section of sfrc member is uncracked until tensile stress does not exceed the critical value. theretofore by provisions of ec2 the full section is assumed to be elastic (fig. 1). steel fibre can change the tensile strength of concrete depending on fibre parameters. however in the calculations of the crack width opening of sfrc members it can be assumed approximately that the tensile strength of sfrc is equal to tensile strength of concrete (jansson 2007). in more details, the tensile strength of sfrc is studied in the other publications – naaman 2003, etc. in this case a cracking moment is calculated according to a formula (1): elctmcrc wfm ⋅= , and strain distribution given in fig. 1 (singly reinforced section). fig. 1. stress and strain distribution in uncracked section of sfrc flexural member the stress and strain distribution is analogical in doubly reinforced section, but the top reinforcement should be considered in that case. 2.2.crack width calculation method proposed by rilem tc 162-tdf for the crack width calculation of steel fibre and ordinary reinforced concrete members rilem has proposed an application of crack width calculation method given in old env 1992-1-1:1991. the calculation method of env 1992-1-1:1991 was supplemented marginally. the coefficient which reduces average crack spacing was involved. this coefficient depends on parameters of the steel fibre. furthermore, the stress in tensile reinforcement (σ s and σ sr ) should be calculated considering that the steel fibres, which cross the crack, take over the residual tensile stresses (σ fb ) uniformly through the all crack height. the stress and strain distribution in the cracked section is given in fig. 2. in this case, the residual tensile stress is taken over in a part of the crack height. such stress distribution could be obtained when the flexural member has a notch. here a fb is the section height where the steel fibre does not take over the residual tensile stress. in other cases, when there is no factors, which can reduce the area of the residual tensile stress, then a fb = 0. fig. 2. stress and strain distribution in cracked section of sfrc flexural member the method proposed by rilem indicates that the residual tensile stress should be calculated according to the formula (2) (rilem tc 162-tdf 2003): 1, 45.0 rmfb f=σ , (2) where: f rm,1 – the mean value of the flexural residual tensile strength, obtained by three–point bending test method. in more details this test are discussed in section 2.4. according to the above discussed method the crack width is calculated by the formula (3): smrmk sw εβ = , (3) where: w k – the final crack width, s rm – the average final crack spacing, ε sm – the mean strain in the tension reinforcement, β – coefficient relating the average crack width with the design value (for load induced cracking β = 1.7). the mean strain in the tension reinforcement ε sm is calculated according to the formula (4): ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 21 1 s sr s s sm e σ σ ββ σ ε , (4) where: σ s – the stress in the tensile reinforcement calculated on the basis of a cracked section (fig. 2), σ sr – the stress in the tensile reinforcement calculated on the basis of a cracked section under loading conditions causing first cracking (fig. 2), β 1 – coefficient which takes account of the bond properties of the bars, β 2 – coefficient which takes account of the duration of the loading or of repeated loading. the stresses in the tension reinforcement σ s1 and σ sr1 can be obtained from the system of equilibrium equations of forces and moments. this system for singly reinforced sfrc flexural members (when a fb = 0) is given in the equation (5): (2) where: frm,1 – the mean value of the flexural residual tensile strength, obtained by three–point bending test method. in more details this test are discussed in section 2.4. according to the above discussed method the crack width is calculated by the formula (3): reinforcement were also measured. the experimental crack widths of full scale beams reinforced with steel fibre and ordinary reinforcement were taken from the reference (ulbinas 2012). comprehensive analysis and the comparison of calculated crack widths and the experimental results are also executed in this paper. 2. methods 2.1. verification of crack opening a cross section of sfrc member is uncracked until tensile stress does not exceed the critical value. theretofore by provisions of ec2 the full section is assumed to be elastic (fig. 1). steel fibre can change the tensile strength of concrete depending on fibre parameters. however in the calculations of the crack width opening of sfrc members it can be assumed approximately that the tensile strength of sfrc is equal to tensile strength of concrete (jansson 2007). in more details, the tensile strength of sfrc is studied in the other publications – naaman 2003, etc. in this case a cracking moment is calculated according to a formula (1): elctmcrc wfm ⋅= , and strain distribution given in fig. 1 (singly reinforced section). fig. 1. stress and strain distribution in uncracked section of sfrc flexural member the stress and strain distribution is analogical in doubly reinforced section, but the top reinforcement should be considered in that case. 2.2.crack width calculation method proposed by rilem tc 162-tdf for the crack width calculation of steel fibre and ordinary reinforced concrete members rilem has proposed an application of crack width calculation method given in old env 1992-1-1:1991. the calculation method of env 1992-1-1:1991 was supplemented marginally. the coefficient which reduces average crack spacing was involved. this coefficient depends on parameters of the steel fibre. furthermore, the stress in tensile reinforcement (σ s and σ sr ) should be calculated considering that the steel fibres, which cross the crack, take over the residual tensile stresses (σ fb ) uniformly through the all crack height. the stress and strain distribution in the cracked section is given in fig. 2. in this case, the residual tensile stress is taken over in a part of the crack height. such stress distribution could be obtained when the flexural member has a notch. here a fb is the section height where the steel fibre does not take over the residual tensile stress. in other cases, when there is no factors, which can reduce the area of the residual tensile stress, then a fb = 0. fig. 2. stress and strain distribution in cracked section of sfrc flexural member the method proposed by rilem indicates that the residual tensile stress should be calculated according to the formula (2) (rilem tc 162-tdf 2003): 1, 45.0 rmfb f=σ , (2) where: f rm,1 – the mean value of the flexural residual tensile strength, obtained by three–point bending test method. in more details this test are discussed in section 2.4. according to the above discussed method the crack width is calculated by the formula (3): smrmk sw εβ = , (3) where: w k – the final crack width, s rm – the average final crack spacing, ε sm – the mean strain in the tension reinforcement, β – coefficient relating the average crack width with the design value (for load induced cracking β = 1.7). the mean strain in the tension reinforcement ε sm is calculated according to the formula (4): ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 21 1 s sr s s sm e σ σ ββ σ ε , (4) where: σ s – the stress in the tensile reinforcement calculated on the basis of a cracked section (fig. 2), σ sr – the stress in the tensile reinforcement calculated on the basis of a cracked section under loading conditions causing first cracking (fig. 2), β 1 – coefficient which takes account of the bond properties of the bars, β 2 – coefficient which takes account of the duration of the loading or of repeated loading. the stresses in the tension reinforcement σ s1 and σ sr1 can be obtained from the system of equilibrium equations of forces and moments. this system for singly reinforced sfrc flexural members (when a fb = 0) is given in the equation (5): (3) where: wk – the final crack width, srm – the average final crack spacing, εsm – the mean strain in the tension reinforcement, β – coefficient relating the average crack width with the design value (for load induced cracking β = 1.7). the mean strain in the tension reinforcement εsm is calculated according to the formula (4): reinforcement were also measured. the experimental crack widths of full scale beams reinforced with steel fibre and ordinary reinforcement were taken from the reference (ulbinas 2012). comprehensive analysis and the comparison of calculated crack widths and the experimental results are also executed in this paper. 2. methods 2.1. verification of crack opening a cross section of sfrc member is uncracked until tensile stress does not exceed the critical value. theretofore by provisions of ec2 the full section is assumed to be elastic (fig. 1). steel fibre can change the tensile strength of concrete depending on fibre parameters. however in the calculations of the crack width opening of sfrc members it can be assumed approximately that the tensile strength of sfrc is equal to tensile strength of concrete (jansson 2007). in more details, the tensile strength of sfrc is studied in the other publications – naaman 2003, etc. in this case a cracking moment is calculated according to a formula (1): elctmcrc wfm ⋅= , and strain distribution given in fig. 1 (singly reinforced section). fig. 1. stress and strain distribution in uncracked section of sfrc flexural member the stress and strain distribution is analogical in doubly reinforced section, but the top reinforcement should be considered in that case. 2.2.crack width calculation method proposed by rilem tc 162-tdf for the crack width calculation of steel fibre and ordinary reinforced concrete members rilem has proposed an application of crack width calculation method given in old env 1992-1-1:1991. the calculation method of env 1992-1-1:1991 was supplemented marginally. the coefficient which reduces average crack spacing was involved. this coefficient depends on parameters of the steel fibre. furthermore, the stress in tensile reinforcement (σ s and σ sr ) should be calculated considering that the steel fibres, which cross the crack, take over the residual tensile stresses (σ fb ) uniformly through the all crack height. the stress and strain distribution in the cracked section is given in fig. 2. in this case, the residual tensile stress is taken over in a part of the crack height. such stress distribution could be obtained when the flexural member has a notch. here a fb is the section height where the steel fibre does not take over the residual tensile stress. in other cases, when there is no factors, which can reduce the area of the residual tensile stress, then a fb = 0. fig. 2. stress and strain distribution in cracked section of sfrc flexural member the method proposed by rilem indicates that the residual tensile stress should be calculated according to the formula (2) (rilem tc 162-tdf 2003): 1, 45.0 rmfb f=σ , (2) where: f rm,1 – the mean value of the flexural residual tensile strength, obtained by three–point bending test method. in more details this test are discussed in section 2.4. according to the above discussed method the crack width is calculated by the formula (3): smrmk sw εβ = , (3) where: w k – the final crack width, s rm – the average final crack spacing, ε sm – the mean strain in the tension reinforcement, β – coefficient relating the average crack width with the design value (for load induced cracking β = 1.7). the mean strain in the tension reinforcement ε sm is calculated according to the formula (4): ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= 2 21 1 s sr s s sm e σ σ ββ σ ε , (4) where: σ s – the stress in the tensile reinforcement calculated on the basis of a cracked section (fig. 2), σ sr – the stress in the tensile reinforcement calculated on the basis of a cracked section under loading conditions causing first cracking (fig. 2), β 1 – coefficient which takes account of the bond properties of the bars, β 2 – coefficient which takes account of the duration of the loading or of repeated loading. the stresses in the tension reinforcement σ s1 and σ sr1 can be obtained from the system of equilibrium equations of forces and moments. this system for singly reinforced sfrc flexural members (when a fb = 0) is given in the equation (5): (4) 52 where: σs – the stress in the tensile reinforcement calculated on the basis of a cracked section (fig. 2), σsr – the stress in the tensile reinforcement calculated on the basis of a cracked section under loading conditions causing first cracking (fig. 2), β1 – coefficient which takes account of the bond properties of the bars, β2 – coefficient which takes account of the duration of the loading or of repeated loading. the stresses in the tension reinforcement σs1 and σsr1 can be obtained from the system of equilibrium equations of forces and moments. this system for singly reinforced sfrc flexural members (when afb = 0) is given in the equation (5): ( ) ( ) ( ) ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =−⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −+⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +− =−−− − 0 362 0 2 11 11 2 1 ekssfb fbss e s m x daσ xh xhbσ xhbσaσ xdα bxσ , (5) the average crack spacing s rm is calculated according to the formula (6): ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 25.050 21 l kks r b rm , (6) where: b – reinforcement bar diameter, k 1 – a coefficient which takes account of the bond properties of the reinforcement, k 2 – a coefficient which takes account of the form of strain distribution, ρ r – the effective reinforcement ratio (a s1 /a c,eff ), l – steel fibre length, – steel fibre diameter. 50/(l/ ) ≤ 1 – a rilem proposed coefficient, which considers the influence of the steel fibre on the average crack spacing. however, this coefficient only considers the influence of length and diameter of the steel fibre, but it does not consider the fibre content. it is also important to note the fact for the flexural members the effective tension area (a c,eff ) should be lesser value of 2.5b(h – d) or b(h – x)/3. when the depth of tension zone is small enough, then the second expression is used to determine the effective tension area of the concrete (env 1992-1-1:1991, en 1992-1-1:2004). 2.3. supplemented and corrected en 1992-1-1:2004 crack width calculation methods it is possible to calculate the crack width of steel fibre and ordinary reinforced concrete flexural members according to a new en 1992-1-1:2004 (hereafter ec2) method. however it should be done some modifications, analogical as in rilem method. here the crack width is calculated according to the formula (7) (supplemented method of ec2). ( ) cmsmr,k εεsw −= max , (7) where: s r,max – the maximum crack spacing; ε sm – the mean strain in the reinforcement; ε cm – the mean strain in the concrete between the cracks. the difference of the strain (ε sm and ε cm ): ( ) s s s effpe effp effct ts cmsm ee f k σ ρα ρ σ εε 6.0 1 , , , ≥ +− =− , (8) where: σ s – the stress in the tension reinforcement assuming the cracked section. determination of σ s was discused above (fig. 2). k t – a factor dependent on the duration of the load, f ct,eff – the mean value of the tensile strength of the concrete effective at the time when the cracks may first be expected to occur, ρ p,eff – reinforcement ratio for longitudinal reinforcement (ρ p,eff = ρ r ), α e – ratio e s /e cm , where e cm and e s is the secant modulus of elasticity of the concrete and the steel bars. the expression of the maximum crack spacing is also supplemented with the coefficient which was suggested by rilem. then the maximum crack spacing: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 425.04.3 , 21max, l kkcs effp r , (9) where: c – the cover to the longitudinal reinforcement, ρ p,eff – the effective reinforcement ratio, – the reinforcement bar diameter, k 1 – the coefficient which takes account of the bond properties of the bonded reinforcement, k 2 – the coefficient which takes account of the distribution of strain. the coefficients k 1 and k 2 are the same as in rilem method. however, the rilem proposed coefficient (50/(l/ )) does not reflect accurately the influence of the fibre content on the distance between the cracks. whereas the crack spacing differs together with the change of the fibre content, therefore löfgren, jansson and the others have proposed the slightly different expression (10) of the maximum crack spacing in their publications (jansson et. al. 2010, löfgren 2007). there is no rilem proposed coefficient in this expression, however the coefficient k 5 is used to reduce maximum crack spacing depending on the residual tensile stress. whereas the residual tensile stress depends on the parameters of steel fibre (aspect ratio – l fb /d fb ), therefore this coefficient also considers aspect ratio. effp r kkkcs , 521max, 425.04.3 ρ φ += , (10) where: the discussed coefficient k 5 is calculated according to the formula (11). the other coefficients were discussed above. ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= ctm resft f f k . 5 1 , (11) where: f ft.res – the residual tensile stress of sfrc (f ft.res = σ fb ). 2.4. experimental program the experimental program was performed in kaunas university of technology in order to determine the influence of the steel fibre for the cracking of steel fibre and ordinary reinforced concrete flexural members. during the experiments the influence of f–cmod (load – crack mouth opening displacement) was obtained and then the residual flexural tensile strength (f r,1 ) and limit of proportionality (lop) were estimated. these tests were performed according to requirements of the en 14651:2005+a1:2007 standard, which is analogical as given in rilem tc 162-tdf (2002). the tests were performed under cmod control. the test scheme is given in fig. 3. . (5) the average crack spacing srm is calculated according to the formula (6): ( ) ( ) ( ) ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =−⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −+⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +− =−−− − 0 362 0 2 11 11 2 1 ekssfb fbss e s m x daσ xh xhbσ xhbσaσ xdα bxσ , (5) the average crack spacing s rm is calculated according to the formula (6): ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 25.050 21 l kks r b rm , (6) where: b – reinforcement bar diameter, k 1 – a coefficient which takes account of the bond properties of the reinforcement, k 2 – a coefficient which takes account of the form of strain distribution, ρ r – the effective reinforcement ratio (a s1 /a c,eff ), l – steel fibre length, – steel fibre diameter. 50/(l/ ) ≤ 1 – a rilem proposed coefficient, which considers the influence of the steel fibre on the average crack spacing. however, this coefficient only considers the influence of length and diameter of the steel fibre, but it does not consider the fibre content. it is also important to note the fact for the flexural members the effective tension area (a c,eff ) should be lesser value of 2.5b(h – d) or b(h – x)/3. when the depth of tension zone is small enough, then the second expression is used to determine the effective tension area of the concrete (env 1992-1-1:1991, en 1992-1-1:2004). 2.3. supplemented and corrected en 1992-1-1:2004 crack width calculation methods it is possible to calculate the crack width of steel fibre and ordinary reinforced concrete flexural members according to a new en 1992-1-1:2004 (hereafter ec2) method. however it should be done some modifications, analogical as in rilem method. here the crack width is calculated according to the formula (7) (supplemented method of ec2). ( ) cmsmr,k εεsw −= max , (7) where: s r,max – the maximum crack spacing; ε sm – the mean strain in the reinforcement; ε cm – the mean strain in the concrete between the cracks. the difference of the strain (ε sm and ε cm ): ( ) s s s effpe effp effct ts cmsm ee f k σ ρα ρ σ εε 6.0 1 , , , ≥ +− =− , (8) where: σ s – the stress in the tension reinforcement assuming the cracked section. determination of σ s was discused above (fig. 2). k t – a factor dependent on the duration of the load, f ct,eff – the mean value of the tensile strength of the concrete effective at the time when the cracks may first be expected to occur, ρ p,eff – reinforcement ratio for longitudinal reinforcement (ρ p,eff = ρ r ), α e – ratio e s /e cm , where e cm and e s is the secant modulus of elasticity of the concrete and the steel bars. the expression of the maximum crack spacing is also supplemented with the coefficient which was suggested by rilem. then the maximum crack spacing: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 425.04.3 , 21max, l kkcs effp r , (9) where: c – the cover to the longitudinal reinforcement, ρ p,eff – the effective reinforcement ratio, – the reinforcement bar diameter, k 1 – the coefficient which takes account of the bond properties of the bonded reinforcement, k 2 – the coefficient which takes account of the distribution of strain. the coefficients k 1 and k 2 are the same as in rilem method. however, the rilem proposed coefficient (50/(l/ )) does not reflect accurately the influence of the fibre content on the distance between the cracks. whereas the crack spacing differs together with the change of the fibre content, therefore löfgren, jansson and the others have proposed the slightly different expression (10) of the maximum crack spacing in their publications (jansson et. al. 2010, löfgren 2007). there is no rilem proposed coefficient in this expression, however the coefficient k 5 is used to reduce maximum crack spacing depending on the residual tensile stress. whereas the residual tensile stress depends on the parameters of steel fibre (aspect ratio – l fb /d fb ), therefore this coefficient also considers aspect ratio. effp r kkkcs , 521max, 425.04.3 ρ φ += , (10) where: the discussed coefficient k 5 is calculated according to the formula (11). the other coefficients were discussed above. ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= ctm resft f f k . 5 1 , (11) where: f ft.res – the residual tensile stress of sfrc (f ft.res = σ fb ). 2.4. experimental program the experimental program was performed in kaunas university of technology in order to determine the influence of the steel fibre for the cracking of steel fibre and ordinary reinforced concrete flexural members. during the experiments the influence of f–cmod (load – crack mouth opening displacement) was obtained and then the residual flexural tensile strength (f r,1 ) and limit of proportionality (lop) were estimated. these tests were performed according to requirements of the en 14651:2005+a1:2007 standard, which is analogical as given in rilem tc 162-tdf (2002). the tests were performed under cmod control. the test scheme is given in fig. 3. (6) where: φb – reinforcement bar diameter, k1 – a coefficient which takes account of the bond properties of the reinforcement, k2 – a coefficient which takes account of the form of strain distribution, ρr – the effective reinforcement ratio (as1/ac,eff), l – steel fibre length, φ – steel fibre diameter. 50/(l/φ) ≤ 1 – a rilem proposed coefficient, which considers the influence of the steel fibre on the average crack spacing. however, this coefficient only considers the influence of length and diameter of the steel fibre, but it does not consider the fibre content. it is also important to note the fact for the flexural members the effective tension area (ac,eff) should be lesser value of 2.5b(h – d) or b(h – x)/3. when the depth of tension zone is small enough, then the second expression is used to determine the effective tension area of the concrete (env 1992-1-1:1991, en 1992-1-1:2004). 2.3. supplemented and corrected en 1992-1-1:2004 crack width calculation methods it is possible to calculate the crack width of steel fibre and ordinary reinforced concrete flexural members according to a new en 1992-1-1:2004 (hereafter ec2) method. however it should be done some modifications, analogical as in rilem method. here the crack width is calculated according to the formula (7) (supplemented method of ec2). ( ) ( ) ( ) ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =−⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −+⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +− =−−− − 0 362 0 2 11 11 2 1 ekssfb fbss e s m x daσ xh xhbσ xhbσaσ xdα bxσ , (5) the average crack spacing s rm is calculated according to the formula (6): ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 25.050 21 l kks r b rm , (6) where: b – reinforcement bar diameter, k 1 – a coefficient which takes account of the bond properties of the reinforcement, k 2 – a coefficient which takes account of the form of strain distribution, ρ r – the effective reinforcement ratio (a s1 /a c,eff ), l – steel fibre length, – steel fibre diameter. 50/(l/ ) ≤ 1 – a rilem proposed coefficient, which considers the influence of the steel fibre on the average crack spacing. however, this coefficient only considers the influence of length and diameter of the steel fibre, but it does not consider the fibre content. it is also important to note the fact for the flexural members the effective tension area (a c,eff ) should be lesser value of 2.5b(h – d) or b(h – x)/3. when the depth of tension zone is small enough, then the second expression is used to determine the effective tension area of the concrete (env 1992-1-1:1991, en 1992-1-1:2004). 2.3. supplemented and corrected en 1992-1-1:2004 crack width calculation methods it is possible to calculate the crack width of steel fibre and ordinary reinforced concrete flexural members according to a new en 1992-1-1:2004 (hereafter ec2) method. however it should be done some modifications, analogical as in rilem method. here the crack width is calculated according to the formula (7) (supplemented method of ec2). ( ) cmsmr,k εεsw −= max , (7) where: s r,max – the maximum crack spacing; ε sm – the mean strain in the reinforcement; ε cm – the mean strain in the concrete between the cracks. the difference of the strain (ε sm and ε cm ): ( ) s s s effpe effp effct ts cmsm ee f k σ ρα ρ σ εε 6.0 1 , , , ≥ +− =− , (8) where: σ s – the stress in the tension reinforcement assuming the cracked section. determination of σ s was discused above (fig. 2). k t – a factor dependent on the duration of the load, f ct,eff – the mean value of the tensile strength of the concrete effective at the time when the cracks may first be expected to occur, ρ p,eff – reinforcement ratio for longitudinal reinforcement (ρ p,eff = ρ r ), α e – ratio e s /e cm , where e cm and e s is the secant modulus of elasticity of the concrete and the steel bars. the expression of the maximum crack spacing is also supplemented with the coefficient which was suggested by rilem. then the maximum crack spacing: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 425.04.3 , 21max, l kkcs effp r , (9) where: c – the cover to the longitudinal reinforcement, ρ p,eff – the effective reinforcement ratio, – the reinforcement bar diameter, k 1 – the coefficient which takes account of the bond properties of the bonded reinforcement, k 2 – the coefficient which takes account of the distribution of strain. the coefficients k 1 and k 2 are the same as in rilem method. however, the rilem proposed coefficient (50/(l/ )) does not reflect accurately the influence of the fibre content on the distance between the cracks. whereas the crack spacing differs together with the change of the fibre content, therefore löfgren, jansson and the others have proposed the slightly different expression (10) of the maximum crack spacing in their publications (jansson et. al. 2010, löfgren 2007). there is no rilem proposed coefficient in this expression, however the coefficient k 5 is used to reduce maximum crack spacing depending on the residual tensile stress. whereas the residual tensile stress depends on the parameters of steel fibre (aspect ratio – l fb /d fb ), therefore this coefficient also considers aspect ratio. effp r kkkcs , 521max, 425.04.3 ρ φ += , (10) where: the discussed coefficient k 5 is calculated according to the formula (11). the other coefficients were discussed above. ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= ctm resft f f k . 5 1 , (11) where: f ft.res – the residual tensile stress of sfrc (f ft.res = σ fb ). 2.4. experimental program the experimental program was performed in kaunas university of technology in order to determine the influence of the steel fibre for the cracking of steel fibre and ordinary reinforced concrete flexural members. during the experiments the influence of f–cmod (load – crack mouth opening displacement) was obtained and then the residual flexural tensile strength (f r,1 ) and limit of proportionality (lop) were estimated. these tests were performed according to requirements of the en 14651:2005+a1:2007 standard, which is analogical as given in rilem tc 162-tdf (2002). the tests were performed under cmod control. the test scheme is given in fig. 3. (7) where: sr,max – the maximum crack spacing; εsm – the mean strain in the reinforcement; εcm – the mean strain in the concrete between the cracks. the difference of the strain (εsm and εcm): ( ) ( ) ( ) ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =−⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −+⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +− =−−− − 0 362 0 2 11 11 2 1 ekssfb fbss e s m x daσ xh xhbσ xhbσaσ xdα bxσ , (5) the average crack spacing s rm is calculated according to the formula (6): ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 25.050 21 l kks r b rm , (6) where: b – reinforcement bar diameter, k 1 – a coefficient which takes account of the bond properties of the reinforcement, k 2 – a coefficient which takes account of the form of strain distribution, ρ r – the effective reinforcement ratio (a s1 /a c,eff ), l – steel fibre length, – steel fibre diameter. 50/(l/ ) ≤ 1 – a rilem proposed coefficient, which considers the influence of the steel fibre on the average crack spacing. however, this coefficient only considers the influence of length and diameter of the steel fibre, but it does not consider the fibre content. it is also important to note the fact for the flexural members the effective tension area (a c,eff ) should be lesser value of 2.5b(h – d) or b(h – x)/3. when the depth of tension zone is small enough, then the second expression is used to determine the effective tension area of the concrete (env 1992-1-1:1991, en 1992-1-1:2004). 2.3. supplemented and corrected en 1992-1-1:2004 crack width calculation methods it is possible to calculate the crack width of steel fibre and ordinary reinforced concrete flexural members according to a new en 1992-1-1:2004 (hereafter ec2) method. however it should be done some modifications, analogical as in rilem method. here the crack width is calculated according to the formula (7) (supplemented method of ec2). ( ) cmsmr,k εεsw −= max , (7) where: s r,max – the maximum crack spacing; ε sm – the mean strain in the reinforcement; ε cm – the mean strain in the concrete between the cracks. the difference of the strain (ε sm and ε cm ): ( ) s s s effpe effp effct ts cmsm ee f k σ ρα ρ σ εε 6.0 1 , , , ≥ +− =− , (8) where: σ s – the stress in the tension reinforcement assuming the cracked section. determination of σ s was discused above (fig. 2). k t – a factor dependent on the duration of the load, f ct,eff – the mean value of the tensile strength of the concrete effective at the time when the cracks may first be expected to occur, ρ p,eff – reinforcement ratio for longitudinal reinforcement (ρ p,eff = ρ r ), α e – ratio e s /e cm , where e cm and e s is the secant modulus of elasticity of the concrete and the steel bars. the expression of the maximum crack spacing is also supplemented with the coefficient which was suggested by rilem. then the maximum crack spacing: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 425.04.3 , 21max, l kkcs effp r , (9) where: c – the cover to the longitudinal reinforcement, ρ p,eff – the effective reinforcement ratio, – the reinforcement bar diameter, k 1 – the coefficient which takes account of the bond properties of the bonded reinforcement, k 2 – the coefficient which takes account of the distribution of strain. the coefficients k 1 and k 2 are the same as in rilem method. however, the rilem proposed coefficient (50/(l/ )) does not reflect accurately the influence of the fibre content on the distance between the cracks. whereas the crack spacing differs together with the change of the fibre content, therefore löfgren, jansson and the others have proposed the slightly different expression (10) of the maximum crack spacing in their publications (jansson et. al. 2010, löfgren 2007). there is no rilem proposed coefficient in this expression, however the coefficient k 5 is used to reduce maximum crack spacing depending on the residual tensile stress. whereas the residual tensile stress depends on the parameters of steel fibre (aspect ratio – l fb /d fb ), therefore this coefficient also considers aspect ratio. effp r kkkcs , 521max, 425.04.3 ρ φ += , (10) where: the discussed coefficient k 5 is calculated according to the formula (11). the other coefficients were discussed above. ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= ctm resft f f k . 5 1 , (11) where: f ft.res – the residual tensile stress of sfrc (f ft.res = σ fb ). 2.4. experimental program the experimental program was performed in kaunas university of technology in order to determine the influence of the steel fibre for the cracking of steel fibre and ordinary reinforced concrete flexural members. during the experiments the influence of f–cmod (load – crack mouth opening displacement) was obtained and then the residual flexural tensile strength (f r,1 ) and limit of proportionality (lop) were estimated. these tests were performed according to requirements of the en 14651:2005+a1:2007 standard, which is analogical as given in rilem tc 162-tdf (2002). the tests were performed under cmod control. the test scheme is given in fig. 3. (8) where: σs – the stress in the tension reinforcement assuming the cracked section. determination of σs was discused above (fig. 2). kt – a factor dependent on the duration of the load, fct,eff – the mean value of the tensile strength of the concrete effective at the time when the cracks may first be expected to occur, ρp,eff – reinforcement ratio for longitudinal reinforcement (ρp,eff = ρr), αe – ratio es/ecm, where ecm and es is the secant modulus of elasticity of the concrete and the steel bars. the expression of the maximum crack spacing is also supplemented with the coefficient which was suggested by rilem. then the maximum crack spacing: ( ) ( ) ( ) ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =−⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −+⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +− =−−− − 0 362 0 2 11 11 2 1 ekssfb fbss e s m x daσ xh xhbσ xhbσaσ xdα bxσ , (5) the average crack spacing s rm is calculated according to the formula (6): ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 25.050 21 l kks r b rm , (6) where: b – reinforcement bar diameter, k 1 – a coefficient which takes account of the bond properties of the reinforcement, k 2 – a coefficient which takes account of the form of strain distribution, ρ r – the effective reinforcement ratio (a s1 /a c,eff ), l – steel fibre length, – steel fibre diameter. 50/(l/ ) ≤ 1 – a rilem proposed coefficient, which considers the influence of the steel fibre on the average crack spacing. however, this coefficient only considers the influence of length and diameter of the steel fibre, but it does not consider the fibre content. it is also important to note the fact for the flexural members the effective tension area (a c,eff ) should be lesser value of 2.5b(h – d) or b(h – x)/3. when the depth of tension zone is small enough, then the second expression is used to determine the effective tension area of the concrete (env 1992-1-1:1991, en 1992-1-1:2004). 2.3. supplemented and corrected en 1992-1-1:2004 crack width calculation methods it is possible to calculate the crack width of steel fibre and ordinary reinforced concrete flexural members according to a new en 1992-1-1:2004 (hereafter ec2) method. however it should be done some modifications, analogical as in rilem method. here the crack width is calculated according to the formula (7) (supplemented method of ec2). ( ) cmsmr,k εεsw −= max , (7) where: s r,max – the maximum crack spacing; ε sm – the mean strain in the reinforcement; ε cm – the mean strain in the concrete between the cracks. the difference of the strain (ε sm and ε cm ): ( ) s s s effpe effp effct ts cmsm ee f k σ ρα ρ σ εε 6.0 1 , , , ≥ +− =− , (8) where: σ s – the stress in the tension reinforcement assuming the cracked section. determination of σ s was discused above (fig. 2). k t – a factor dependent on the duration of the load, f ct,eff – the mean value of the tensile strength of the concrete effective at the time when the cracks may first be expected to occur, ρ p,eff – reinforcement ratio for longitudinal reinforcement (ρ p,eff = ρ r ), α e – ratio e s /e cm , where e cm and e s is the secant modulus of elasticity of the concrete and the steel bars. the expression of the maximum crack spacing is also supplemented with the coefficient which was suggested by rilem. then the maximum crack spacing: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 425.04.3 , 21max, l kkcs effp r , (9) where: c – the cover to the longitudinal reinforcement, ρ p,eff – the effective reinforcement ratio, – the reinforcement bar diameter, k 1 – the coefficient which takes account of the bond properties of the bonded reinforcement, k 2 – the coefficient which takes account of the distribution of strain. the coefficients k 1 and k 2 are the same as in rilem method. however, the rilem proposed coefficient (50/(l/ )) does not reflect accurately the influence of the fibre content on the distance between the cracks. whereas the crack spacing differs together with the change of the fibre content, therefore löfgren, jansson and the others have proposed the slightly different expression (10) of the maximum crack spacing in their publications (jansson et. al. 2010, löfgren 2007). there is no rilem proposed coefficient in this expression, however the coefficient k 5 is used to reduce maximum crack spacing depending on the residual tensile stress. whereas the residual tensile stress depends on the parameters of steel fibre (aspect ratio – l fb /d fb ), therefore this coefficient also considers aspect ratio. effp r kkkcs , 521max, 425.04.3 ρ φ += , (10) where: the discussed coefficient k 5 is calculated according to the formula (11). the other coefficients were discussed above. ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= ctm resft f f k . 5 1 , (11) where: f ft.res – the residual tensile stress of sfrc (f ft.res = σ fb ). 2.4. experimental program the experimental program was performed in kaunas university of technology in order to determine the influence of the steel fibre for the cracking of steel fibre and ordinary reinforced concrete flexural members. during the experiments the influence of f–cmod (load – crack mouth opening displacement) was obtained and then the residual flexural tensile strength (f r,1 ) and limit of proportionality (lop) were estimated. these tests were performed according to requirements of the en 14651:2005+a1:2007 standard, which is analogical as given in rilem tc 162-tdf (2002). the tests were performed under cmod control. the test scheme is given in fig. 3. (9) where: c – the cover to the longitudinal reinforcement, ρp,eff – the effective reinforcement ratio, φ – the reinforcement bar diameter, k1 – the coefficient which takes account of the bond properties of the bonded reinforcement, k2 – the coefficient which takes account of the distribution of strain. the coefficients k1 and k2 are the same as in rilem method. however, the rilem proposed coefficient (50/(l/φ)) does not reflect accurately the influence of the fibre content on the distance between the cracks. whereas the crack spacing differs together with the change of the fibre content, therefore löfgren, jansson and the others have proposed the slightly different expression (10) of the maximum crack spacing in their publications (jansson et. al., 2010; löfgren, 2007). there is no rilem proposed coefficient in this expression, however the coefficient k5 is used to reduce maximum crack spacing depending on the residual tensile stress. whereas the residual tensile stress depends on the parameters of steel fibre (aspect ratio – lfb/dfb), therefore this coefficient also considers aspect ratio. ( ) ( ) ( ) ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =−⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −+⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +− =−−− − 0 362 0 2 11 11 2 1 ekssfb fbss e s m x daσ xh xhbσ xhbσaσ xdα bxσ , (5) the average crack spacing s rm is calculated according to the formula (6): ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 25.050 21 l kks r b rm , (6) where: b – reinforcement bar diameter, k 1 – a coefficient which takes account of the bond properties of the reinforcement, k 2 – a coefficient which takes account of the form of strain distribution, ρ r – the effective reinforcement ratio (a s1 /a c,eff ), l – steel fibre length, – steel fibre diameter. 50/(l/ ) ≤ 1 – a rilem proposed coefficient, which considers the influence of the steel fibre on the average crack spacing. however, this coefficient only considers the influence of length and diameter of the steel fibre, but it does not consider the fibre content. it is also important to note the fact for the flexural members the effective tension area (a c,eff ) should be lesser value of 2.5b(h – d) or b(h – x)/3. when the depth of tension zone is small enough, then the second expression is used to determine the effective tension area of the concrete (env 1992-1-1:1991, en 1992-1-1:2004). 2.3. supplemented and corrected en 1992-1-1:2004 crack width calculation methods it is possible to calculate the crack width of steel fibre and ordinary reinforced concrete flexural members according to a new en 1992-1-1:2004 (hereafter ec2) method. however it should be done some modifications, analogical as in rilem method. here the crack width is calculated according to the formula (7) (supplemented method of ec2). ( ) cmsmr,k εεsw −= max , (7) where: s r,max – the maximum crack spacing; ε sm – the mean strain in the reinforcement; ε cm – the mean strain in the concrete between the cracks. the difference of the strain (ε sm and ε cm ): ( ) s s s effpe effp effct ts cmsm ee f k σ ρα ρ σ εε 6.0 1 , , , ≥ +− =− , (8) where: σ s – the stress in the tension reinforcement assuming the cracked section. determination of σ s was discused above (fig. 2). k t – a factor dependent on the duration of the load, f ct,eff – the mean value of the tensile strength of the concrete effective at the time when the cracks may first be expected to occur, ρ p,eff – reinforcement ratio for longitudinal reinforcement (ρ p,eff = ρ r ), α e – ratio e s /e cm , where e cm and e s is the secant modulus of elasticity of the concrete and the steel bars. the expression of the maximum crack spacing is also supplemented with the coefficient which was suggested by rilem. then the maximum crack spacing: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 425.04.3 , 21max, l kkcs effp r , (9) where: c – the cover to the longitudinal reinforcement, ρ p,eff – the effective reinforcement ratio, – the reinforcement bar diameter, k 1 – the coefficient which takes account of the bond properties of the bonded reinforcement, k 2 – the coefficient which takes account of the distribution of strain. the coefficients k 1 and k 2 are the same as in rilem method. however, the rilem proposed coefficient (50/(l/ )) does not reflect accurately the influence of the fibre content on the distance between the cracks. whereas the crack spacing differs together with the change of the fibre content, therefore löfgren, jansson and the others have proposed the slightly different expression (10) of the maximum crack spacing in their publications (jansson et. al. 2010, löfgren 2007). there is no rilem proposed coefficient in this expression, however the coefficient k 5 is used to reduce maximum crack spacing depending on the residual tensile stress. whereas the residual tensile stress depends on the parameters of steel fibre (aspect ratio – l fb /d fb ), therefore this coefficient also considers aspect ratio. effp r kkkcs , 521max, 425.04.3 ρ φ += , (10) where: the discussed coefficient k 5 is calculated according to the formula (11). the other coefficients were discussed above. ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= ctm resft f f k . 5 1 , (11) where: f ft.res – the residual tensile stress of sfrc (f ft.res = σ fb ). 2.4. experimental program the experimental program was performed in kaunas university of technology in order to determine the influence of the steel fibre for the cracking of steel fibre and ordinary reinforced concrete flexural members. during the experiments the influence of f–cmod (load – crack mouth opening displacement) was obtained and then the residual flexural tensile strength (f r,1 ) and limit of proportionality (lop) were estimated. these tests were performed according to requirements of the en 14651:2005+a1:2007 standard, which is analogical as given in rilem tc 162-tdf (2002). the tests were performed under cmod control. the test scheme is given in fig. 3. (10) where: the discussed coefficient k5 is calculated according to the formula (11). the other coefficients were discussed above. ( ) ( ) ( ) ⎪ ⎪ ⎩ ⎪ ⎪ ⎨ ⎧ =−⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −+⎟ ⎠ ⎞ ⎜ ⎝ ⎛ +− =−−− − 0 362 0 2 11 11 2 1 ekssfb fbss e s m x daσ xh xhbσ xhbσaσ xdα bxσ , (5) the average crack spacing s rm is calculated according to the formula (6): ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 25.050 21 l kks r b rm , (6) where: b – reinforcement bar diameter, k 1 – a coefficient which takes account of the bond properties of the reinforcement, k 2 – a coefficient which takes account of the form of strain distribution, ρ r – the effective reinforcement ratio (a s1 /a c,eff ), l – steel fibre length, – steel fibre diameter. 50/(l/ ) ≤ 1 – a rilem proposed coefficient, which considers the influence of the steel fibre on the average crack spacing. however, this coefficient only considers the influence of length and diameter of the steel fibre, but it does not consider the fibre content. it is also important to note the fact for the flexural members the effective tension area (a c,eff ) should be lesser value of 2.5b(h – d) or b(h – x)/3. when the depth of tension zone is small enough, then the second expression is used to determine the effective tension area of the concrete (env 1992-1-1:1991, en 1992-1-1:2004). 2.3. supplemented and corrected en 1992-1-1:2004 crack width calculation methods it is possible to calculate the crack width of steel fibre and ordinary reinforced concrete flexural members according to a new en 1992-1-1:2004 (hereafter ec2) method. however it should be done some modifications, analogical as in rilem method. here the crack width is calculated according to the formula (7) (supplemented method of ec2). ( ) cmsmr,k εεsw −= max , (7) where: s r,max – the maximum crack spacing; ε sm – the mean strain in the reinforcement; ε cm – the mean strain in the concrete between the cracks. the difference of the strain (ε sm and ε cm ): ( ) s s s effpe effp effct ts cmsm ee f k σ ρα ρ σ εε 6.0 1 , , , ≥ +− =− , (8) where: σ s – the stress in the tension reinforcement assuming the cracked section. determination of σ s was discused above (fig. 2). k t – a factor dependent on the duration of the load, f ct,eff – the mean value of the tensile strength of the concrete effective at the time when the cracks may first be expected to occur, ρ p,eff – reinforcement ratio for longitudinal reinforcement (ρ p,eff = ρ r ), α e – ratio e s /e cm , where e cm and e s is the secant modulus of elasticity of the concrete and the steel bars. the expression of the maximum crack spacing is also supplemented with the coefficient which was suggested by rilem. then the maximum crack spacing: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ += φρ φ / 50 425.04.3 , 21max, l kkcs effp r , (9) where: c – the cover to the longitudinal reinforcement, ρ p,eff – the effective reinforcement ratio, – the reinforcement bar diameter, k 1 – the coefficient which takes account of the bond properties of the bonded reinforcement, k 2 – the coefficient which takes account of the distribution of strain. the coefficients k 1 and k 2 are the same as in rilem method. however, the rilem proposed coefficient (50/(l/ )) does not reflect accurately the influence of the fibre content on the distance between the cracks. whereas the crack spacing differs together with the change of the fibre content, therefore löfgren, jansson and the others have proposed the slightly different expression (10) of the maximum crack spacing in their publications (jansson et. al. 2010, löfgren 2007). there is no rilem proposed coefficient in this expression, however the coefficient k 5 is used to reduce maximum crack spacing depending on the residual tensile stress. whereas the residual tensile stress depends on the parameters of steel fibre (aspect ratio – l fb /d fb ), therefore this coefficient also considers aspect ratio. effp r kkkcs , 521max, 425.04.3 ρ φ += , (10) where: the discussed coefficient k 5 is calculated according to the formula (11). the other coefficients were discussed above. ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −= ctm resft f f k . 5 1 , (11) where: f ft.res – the residual tensile stress of sfrc (f ft.res = σ fb ). 2.4. experimental program the experimental program was performed in kaunas university of technology in order to determine the influence of the steel fibre for the cracking of steel fibre and ordinary reinforced concrete flexural members. during the experiments the influence of f–cmod (load – crack mouth opening displacement) was obtained and then the residual flexural tensile strength (f r,1 ) and limit of proportionality (lop) were estimated. these tests were performed according to requirements of the en 14651:2005+a1:2007 standard, which is analogical as given in rilem tc 162-tdf (2002). the tests were performed under cmod control. the test scheme is given in fig. 3. (11) where: fft.res – the residual tensile stress of sfrc (fft.res = σfb). 2.4. experimental program the experimental program was performed in kaunas university of technology in order to determine the influence of the steel fibre for the cracking of steel fibre and ordinary reinforced concrete flexural members. during the experiments the influence of f–cmod (load – crack mouth opening displacement) was obtained and then the residual flexural tensile strength (fr,1) and limit of proportionality (lop) were estimated. these tests were performed according to requirements of the en 14651:2005+a1:2007 standard, which is analogical as given in rilem tc 162tdf (2002). the tests were performed under cmod control. the test scheme is given in fig. 3. 53 fig. 3. three – point bending test scheme according to the en 14651:2005+a1:2007 standard method the residual flexural tensile strength (fr,1) of sfrc is estimated according to the formula (12), when cmod = 0.5 mm (j=1, i=1). fig. 3. three – point bending test scheme according to the en 14651:2005+a1:2007 standard method the residual flexural tensile strength (f r,1 ) of sfrc is estimated according to the formula (12), when cmod = 0.5 mm (j=1, i=1). 2 , , 2 3 sp ir ir bh lf f = , (12) where: f r,i – load corresponding with cmod = cmod j (j = 1, 2, 3, 4), l – span length, b – width of the specimen, h sp – distance between the tip of the notch and the top of the specimen. the determination of the limit of proportionality (lop) is given in detail in en 14651:2005+a1:2007. this limit indicates the tensile strength of sfrc (flexural members with the notch). in order to determine the tensile strength of concrete the bending tests were performed. the geometry of specimens was analogical to the bending tests given in fig. 3, but this time prisms were without the notch. the mean axial tensile strength of concrete (sfrc) was estimated from the measured flexural tensile strength using the expression (13). it was done because the estimated mean value of the axial tensile strength was used for calculations of the cracking moment and the crack width. ⎟ ⎟ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎜ ⎜ ⎝ ⎛ − = flctm flctm ctm f f f , , ; 1000 150 6.1 min , (13) where: f ctm,fl – the mean flexural tensile strength of the concrete. fig. 4. crack width measurement of steel fibre and ordinary reinforced concrete flexural members 1 in order to compare calculated crack width to the measured values the experimental program was performed with steel fibre and ordinary reinforced small dimension concrete flexural members. the crack width was measured during these experiments. the analogical experimental program was also performed using only ordinary and only steel fibre reinforced small dimension concrete beams. some tests were performed under deformation control (a constant rate of increase of midspan deflection – 0.2 mm/min) and some of them under loading control (the constant rate of load increase – 156 n/s). in order to make only one crack and to control its location (where the maximum bending moment occurs) the specimens had the notch. the geometry of the specimens is the same as in fig. 3. the clear concrete cover of specimens was 25 mm (the concrete cover above the notch was 0 mm). the equipment of the tests is given in fig. 4. the crack widths of these beams were measured at the level of reinforcement using a deformation gauge (fig. 5). fig. 5. crack width measurement of steel fibre and ordinary reinforced concrete flexural members 2 the specimens with the notch were also used to get the tensile strength of the concrete. the main aim of these tests was to establish approximately the difference of the tensile strength of the concrete and sfrc (lop and f ctm,fl,notch ). the cube compressive strength of the concrete and sfrc was also observed. the tests were performed under the requirements of the en 12390-3:2009 standard. modulus of elasticity of the concrete was also measured lastly in this experimental program. the tests were performed under the requirements of the iso 67841982 standard. the grade of the steel rebars which were used in these tests is s400 and its modulus of elasticity e s =200 mpa. the tensile strength of hooked end steel fibre which was used in this tests is f y =1150 mpa and the aspect ratio/fibre length – 67/50. the composition of the concrete and sfrc is given in table 1. table 1. concrete composition composition dosage (kg/m 3 ) cement cem i 42.5 r 318 water 168 coarse aggregate 4/16 960 fine aggregate 0/4 945 fibre content 0 or 30 additional information about all these tests is given in table 2. (12) where: fr,i – load corresponding with cmod = cmodj (j = 1, 2, 3, 4), l – span length, b – width of the specimen, hsp – distance between the tip of the notch and the top of the specimen. the determination of the limit of proportionality (lop) is given in detail in en 14651:2005+a1:2007. this limit indicates the tensile strength of sfrc (flexural members with the notch). in order to determine the tensile strength of concrete the bending tests were performed. the geometry of specimens was analogical to the bending tests given in fig. 3, but this time prisms were without the notch. the mean axial tensile strength of concrete (sfrc) was estimated from the measured flexural tensile strength using the expression (13). it was done because the estimated mean value of the axial tensile strength was used for calculations of the cracking moment and the crack width. fig. 3. three – point bending test scheme according to the en 14651:2005+a1:2007 standard method the residual flexural tensile strength (f r,1 ) of sfrc is estimated according to the formula (12), when cmod = 0.5 mm (j=1, i=1). 2 , , 2 3 sp ir ir bh lf f = , (12) where: f r,i – load corresponding with cmod = cmod j (j = 1, 2, 3, 4), l – span length, b – width of the specimen, h sp – distance between the tip of the notch and the top of the specimen. the determination of the limit of proportionality (lop) is given in detail in en 14651:2005+a1:2007. this limit indicates the tensile strength of sfrc (flexural members with the notch). in order to determine the tensile strength of concrete the bending tests were performed. the geometry of specimens was analogical to the bending tests given in fig. 3, but this time prisms were without the notch. the mean axial tensile strength of concrete (sfrc) was estimated from the measured flexural tensile strength using the expression (13). it was done because the estimated mean value of the axial tensile strength was used for calculations of the cracking moment and the crack width. ⎟ ⎟ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎜ ⎜ ⎝ ⎛ ⎟ ⎟ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎜ ⎜ ⎝ ⎛ − = flctm flctm ctm f f f , , ; 1000 150 6.1 min , (13) where: f ctm,fl – the mean flexural tensile strength of the concrete. fig. 4. crack width measurement of steel fibre and ordinary reinforced concrete flexural members 1 in order to compare calculated crack width to the measured values the experimental program was performed with steel fibre and ordinary reinforced small dimension concrete flexural members. the crack width was measured during these experiments. the analogical experimental program was also performed using only ordinary and only steel fibre reinforced small dimension concrete beams. some tests were performed under deformation control (a constant rate of increase of midspan deflection – 0.2 mm/min) and some of them under loading control (the constant rate of load increase – 156 n/s). in order to make only one crack and to control its location (where the maximum bending moment occurs) the specimens had the notch. the geometry of the specimens is the same as in fig. 3. the clear concrete cover of specimens was 25 mm (the concrete cover above the notch was 0 mm). the equipment of the tests is given in fig. 4. the crack widths of these beams were measured at the level of reinforcement using a deformation gauge (fig. 5). fig. 5. crack width measurement of steel fibre and ordinary reinforced concrete flexural members 2 the specimens with the notch were also used to get the tensile strength of the concrete. the main aim of these tests was to establish approximately the difference of the tensile strength of the concrete and sfrc (lop and f ctm,fl,notch ). the cube compressive strength of the concrete and sfrc was also observed. the tests were performed under the requirements of the en 12390-3:2009 standard. modulus of elasticity of the concrete was also measured lastly in this experimental program. the tests were performed under the requirements of the iso 67841982 standard. the grade of the steel rebars which were used in these tests is s400 and its modulus of elasticity e s =200 mpa. the tensile strength of hooked end steel fibre which was used in this tests is f y =1150 mpa and the aspect ratio/fibre length – 67/50. the composition of the concrete and sfrc is given in table 1. table 1. concrete composition composition dosage (kg/m 3 ) cement cem i 42.5 r 318 water 168 coarse aggregate 4/16 960 fine aggregate 0/4 945 fibre content 0 or 30 additional information about all these tests is given in table 2. (13) where: fctm,fl – the mean flexural tensile strength of the concrete. fig. 4. crack width measurement of steel fibre and ordinary reinforced concrete flexural members 1 in order to compare calculated crack width to the measured values the experimental program was performed with steel fibre and ordinary reinforced small dimension concrete flexural members. the crack width was measured during these experiments. the analogical experimental program was also performed using only ordinary and only steel fibre reinforced small dimension concrete beams. some tests were performed under deformation control (a constant rate of increase of midspan deflection – 0.2 mm/min) and some of them under loading control (the constant rate of load increase – 156 n/s). in order to make only one crack and to control its location (where the maximum bending moment occurs) the specimens had the notch. the geometry of the specimens is the same as in fig. 3. the clear concrete cover of specimens was 25 mm (the concrete cover above the notch was 0 mm). the equipment of the tests is given in fig. 4. the crack widths of these beams were measured at the level of reinforcement using a deformation gauge (fig. 5). fig. 5. crack width measurement of steel fibre and ordinary reinforced concrete flexural members 2 the specimens with the notch were also used to get the tensile strength of the concrete. the main aim of these tests was to establish approximately the difference of the tensile strength of the concrete and sfrc (lop and fctm,fl,notch). the cube compressive strength of the concrete and sfrc was also observed. the tests were performed under the requirements of the en 12390-3:2009 standard. modulus of elasticity of the concrete was also measured lastly in this experimental program. the tests were performed under the requirements of the iso 67841982 standard. the grade of the steel rebars which were used in these tests is s400 and its modulus of elasticity es=200 mpa. the tensile strength of hooked end steel fibre which was used in this tests is fy=1150 mpa and the aspect ratio/fibre length – 67/50. the composition of the concrete and sfrc is given in table 1. table 1. concrete composition composition dosage (kg/m3) cement cem i 42.5 r 318 water 168 coarse aggregate 4/16 960 fine aggregate 0/4 945 fibre content 0 or 30 additional information about all these tests is given in table 2. 54 3. results 3.1 experimental results tests results are presented in table 3 and in fig. 6 – fig. 8. table 3. estimated properties of concrete and sfrc test no. fibre content, kg/m3 parameter notation value, mpa 1 30 frm,1 3.07 1 30 lop 4.24 2 – fctm,fl 4.46 5 – fctm,fl,notch 3.65 9 – fcm.cub 47.04 10 30 fcm,fb.cub 49.66 11 30 ecm 32988 it can be seen from the table 3 that the case of the deflection softening is obtained when the fibre content is 30 kg/m3, because the mean residual tensile strength (frm,1) is less than the limit of the proportionality (lop). in comparison of the results of the tests no. 2 and no. 5 it is observed that the mean flexural tensile strength (fctm,fl) of the specimens with the notch is less. the earlier fracture of the specimens with the notch was obtained due to stress concentrations. the difference of the results could be influenced slightly because of the different loading control. considering to this fact we can state that flexural tensile strength of sfrc is higher than the limit of proportionality (lop). in analogical comparison of the results of the tests no. 1 and no. 5 (lop with fctm,fl,notch), it can be seen that the steel fibre increased significantly the average flexural fracture stress. the number of the specimens with the steel fibre was 12 and the minimum value of lop was obtained 3.82 mpa. however, only 3 specimens without the steel fibre were tested and the minimum fracture stress value reached 3.59 mpa. therefore, it can be seen from table 3 and from above mentioned results that the flexural tensile strength is influenced strongly of the distribution of the steel fibre. due to the small content of the steel fibre and the sufficiently long fibres the compressive strength of the concrete was changed marginally. the similar results have been obtained by l. vandewalle (vandewalle, 2007). the residual tensile strength fr,1 is determined when cmod=0.5 mm. the stress – cmod curves of sfrc is obtained experimentally and is presented in fig 6. here we can see that the distribution of the fibres influences strongly on the residual flexural tensile strength and the scatter of the results is very high. the difference between minimum and maximum values of fr,1 almost reaches the average value (δfr,1 = 2.61 mpa < frm,1 = 3.07 mpa), and the coefficient of variation is equal to 0.234. the analogically high scatter of the results has been observed by other researchers’ who have performed the experimental research by the same method (parmentier et. al., 2008; vandewalle et. al., 2008). fig. 6. residual flexural tensile strength – cmod curves (test no.1) fig. 7 presents f-w curves of 6 specimens from no. 3 and no. 4 tests. it can be seen, that the 30 kg/m3 content of steel fibre not only increased the strength of the member, but also reduced significantly the crack width at the same loading level. for example, when bending moment was equal to 17 knm, then the crack width of the members without the steel fibre reached 4.8 mm, and the crack of the members with the steel fibre – 0.065 mm. however, the load difference from the moment when the crack opens until the fracture of the member is not high for the small cross section members and for the members with the small reinforcement ratio. whereas when the steel fibre was used this difference was higher more than two times. table 2. information of tests (45 specimens) test no. description of specimens geometry of specimens, mm number of specimens fibre content, kg/m3 rebars loading measured parameter or relation 1 prisms with notch 600x150x150 12 30 – under deformation control f–cmod, frm,1, lop 2 prisms without notch 600x150x150 3 – – under deformation control fctm,fl 3 beams with notch 600x150x150 3 – 1ø6 s400 under deformation control f-w (relation) 4 beams with notch 600x150x150 3 30 1ø6 s400 under deformation control f-w (relation) 5 prisms with notch 600x150x150 2 – – under force control fctm,fl,notch 6 beams with notch 600x150x150 2 30 – under force control f-w (relation) 7 beams with notch 600x150x150 2 – 1ø6 s400 under force control f-w (relation) 8 beams with notch 600x150x150 2 30 1ø6 s400 under force control f-w (relation) 9 cubes 100x100x100 4 – – under force control fcm.cub 10 cubes 100x100x100 9 30 – under force control fcm,fb.cub 11 prisms 300x100x100 3 – – under force control ecm 55 fig. 7. f-w curves when loading is performed under deformation control fig. 8. f-w curves when loading is performed under force control fig. 8 presents the f-w curves of 6 specimens from no. 6, no. 7 and no. 8 tests. the consistent pattern of the test no. 1 and no. 6, no. 3 and no. 7, no. 4 and no. 8 are the same although the loading control was different. it can be seen from the comparison of tests no. 3 and no. 7 results that the loading control has no significant influence on the f-w relationship. comparing the results from the tests no. 1 and no. 6 it is also can be seen that curves of the test no. 6 pass between the top and the bottom curves of the test no. 1 (f1,min = 5.75 kn (fr,1,min=1.84 mpa), f1,max = 13.91 kn (fr,1,max=4.45 mpa). however, it is observed that at the same crack width value, the load of the test no. 8 was higher than the load of the test no. 4. considering to the large scatter of the residual flexural tensile strength observed in fig. 6 such increase of the strength could be obtained not due to the loading control, but due to the distribution of the steel fibre. 3.2. comparison of experimental and calculated crack width the crack widths calculated according to the methods presented in section 2 were compared with the experimental results from the tests no. 4 and no. 8. all parameters which are used in the calculations are given in section 3. the comparison of the results is given in fig. 9. it can be seen from fig. 9 that crack widths which are calculated according to the rilem method strongly differ from the experimental results. in most cases, the calculated crack widths more than twice exceed the experimental values. when the experimentally obtained crack widths are wide and calculations are performed according to the supplemented and the corrected ec2 methods then the calculated crack widths can be unreliable. however, when the crack widths are narrower than 0.3 mm, then the calculated crack widths according to these two methods satisfy the experimental crack widths more accurately. fig. 9. the comparison of the calculated and the determinate crack width it is known that the distribution of the steel fibre influence strongly on the residual flexural tensile strength and for the larger cross sections the scatter of the results between separate specimens decreases (jansson, 2007; parmentier et. al., 2008; vandewalle et. al., 2008). due to this reason the scatter of the experimental crack width values of the larger cross section members should also be less and the calculated crack width values should be more accurate. in order to prove this statement the additional research was performed using larger cross section concrete flexural members reinforced with steel fibre and ordinary reinforcement. the experimental data is obtained from d. ulbinas’ phd thesis (ulbinas, 2012). the main data which was used for the calculations is given in table 4. table 4. the main parameters of materials description parameter concrete class c35/45 ecm (from experiments, ref. table 2.1) 34984 mpa fctm (by class, from ec2 table 3.1) 3.2 mpa fibre aspect ratio (lfb/dfb) 55 fibre content 79.24 kg/m3 frm,1 (from exp., ref. fig. 2.11 and fig. 2.12) 5.36 mpa bottom reinforcement (rebars) 3ø10 top reinforcement (rebars) 2ø6 es (from experiments, ref. table 2.1) 20300 mpa the loading scheme of the tests and the cross section which were used for the calculations are given in fig. 10. all additional information is presented in d. ulbinas’ phd thesis (ulbinas, 2012). 56 fig. 10. loading scheme and cross section of specimens (ulbinas 2012) it should be noted that more than twice larger reinforcement ratio was used in the described tests (ulbinas, 2012) than in the tests which are presented in section 2. the comparison of the experimental and the calculated crack widths is given in fig. 11. fig. 11. comparison of experimental and calculated crack widths it can be seen from fig. 11 that quite significant errors are obtained when the crack widths are calculated according to the rilem method. when the crack widths increase then the errors also increase. when the calculations according to this method are performed using 30 knm bending moment the twice larger values of the crack width are obtained comparing to the experimental results. the crack width values calculated according to the supplemented ec2 method quite well coincide with experimental results at the low level of the crack width. however, at the crack width level higher than 0.1 mm the crack widths calculated according to this method vary strongly from the experimental results. the values of the crack widths were obtained slightly less, when the calculations were performed according to the corrected ec2 method. despite of that, this method reflects the consistent pattern of the crack width development the most accurately. 4. discussion analysing the experimental research data it is observed that the scatter of the residual flexural tensile strength is quite significant. because of such variability of the residual flexural tensile strength the measured crack widths of the separate concrete members reinforced with steel fibre and ordinary reinforcement can disagree strongly with the calculated crack widths, while for the for the members without steel fibre these results could be similar. as it was mentioned above, the scatter of the results decreases together with the increase of the cross section dimensions. therefore, the average value of residual flexural tensile strength (frm,1) in some cases can be unreliable for members with the small cross section. it can be seen from the experimental data that the steel fibre can increase the tensile strength of concrete. the more accurate evaluation of the tensile strength of the sfrc could help to carry out calculations of crack width more accurately. it should be noted that in the case of the crack width calculation according to the rilem method, the stress in the tensile reinforcement calculated under loading conditions causing first cracking is considered, while neither the supplemented nor the corrected ec2 method do not take this into account. it could be a reason why the experimentally obtained crack width was less than the calculated value according to the mentioned method for the members with the notch. in this case the calculated crack widths exceed the experimental values when it is more than 0.2 mm level, while such consistent pattern is not observed for the members without the notch. 5. conclusions 1. a review of three crack width calculation methods which is adapted for the flexural members reinforced with the fibre and the ordinary reinforcement was performed. it is observed that in all the cases the stress in the tensile reinforcement is calculated making the assumption that the concrete and the reinforcement behave elastically, and the steel fibre which crosses the cracks takes over the residual tensile stress uniformly. the residual tensile stress should be obtained from the experiments. 2. the number of the specimens has the significant influence on the estimation of the average residual flexural tensile strength (frm,1). the small number of the specimens can affect the significant errors of frm,1 due to the large scatter of the experimental results. 3. from the performed experimental research, it was determined that 30 kg/m3 steel fibre content was quite effective to restrain the crack development and to increase the member strength. here the fibre distribution has decisive influence on the crack width, while the loading control is not significant. 4. it is observed that in the calculations of the crack widths of the small and larger cross section members none of the mentioned methods was absolutely precise. the most significant errors were obtained using the rilem method. depending on the case the more accurate results are obtained using the supplemented and corrected ec2 methods. however, also depending on the case the results obtained using these methods can be unreliable. acknowledgment a part of the experimental research data were used from d. ulbinas’ phd thesis. (ulbinas, 2012). 57 references en 14651:2005+a1:2007. test method for metallic fibre concrete – measuring the flexural tensile strength (limit proportionality (lop), residual). 16 p. en 1992-1-1:2004. eurocode 2: design of concrete structures – part 1-1: general rules and rules for buildings. 225 p. env 1992-1-1:1991. eurocode 2: design of concrete structures – part 1: general rules and rules for buildings. 176 p. en 12390-3:2009. testing hardened concrete part 3: compressive strength of test specimens. 18 p. iso 6784-1982. concrete determination of static modulus of elasticity in compression. 24 p. jansson a. 2007. analysis and design methods for fibre reinforced concrete: a state-of-the-art report, göteborg, dep. of civil and environmental engineering, div. of structural engineering/concrete structures, chalmers university of technology, 178 p. jansson a., löfgren i., gylltoft k. 2008. design methods for fibre – reinforced concrete: a state–of–the art review. nordic concrete research, 2(38), 31–46. jansson a., löfgren i., gylltoft k. 2010. flexural behaviour of members with a combination of steel fibres and conventional reinforcement. nordic concrete research, 2(42), 155–171. löfgren i. 2007. calculation of crack width and crack spacing. in: nordic mini seminar: fibre reinforced concrete, trondheim, norway, 1–12. naaman a. e. 2003. strain hardening and deflection hardening fiber reinforced cement composites. in: high performance fiber reinforced cement composites (hpfrcc4), proceedings of the 4th international rilem workshop, ann arbor, usa, 95–113. parmentier b, vandewalle l, rickstal f. 2008. evaluation of the scatter of the postpeak behaviour of fibre reinforced concrete in bending: a step towards reliability. in: proceedings of the 7th rilem international symposium on fibre reinforced concrete: design and applications befib 2008, chennai, india, 133–143. rilem tc 162-tdf. 2002. recommendations of rilem tc 162-tdf: test and design methods for steel fibre reinforced concrete: bending test. mater struct, 35(253), 579–582. rilem tc 162-tdf. 2003. final recommendation of rilem tc 162-tdf: test and design methods for steel fibre reinforced concrete. mater struct, 36(262), 560–567. ulbinas d., kaklauskas g. 2009. plieno pluoštu armuotų gelžbetoninių elementų pleišėtumo analizė [crack width analysis of steel fiber reinforced concrete elements]. science – future of lithuania, 1(5), 56–62. ulbinas, d. 2012. plieno plaušu armuotų gelžbetoninių elementų pleišėtumo ir standumo analyze [cracking and stiffness analysis of steel fiber reinforced concrete members], daktaro disertacija. vilnius, technika, 98 p. vandewalle l. 2007. postcracking behaviour of hybrid steel fiber reinforced concrete. in: fracture mechanics of concrete and concrete structures – framcos, proceedings of the 6th international conference, catania, italy, 17–22, 1367–1375. vandewalle l., rickstal f., heirman g., parmentier b. 2008. on the round panel and 3-point bending tests. in: fibre reinforced concrete: design and applications – befib 2008, proceedings of the 7th rilem international symposium, chennai, india. 173–182. received 2014 01 31 accepted after revision 2014 02 16 šarūnas kelpša – phd student at kaunas university of technology, faculty of civil engineering and architecture. main research area: strength, stability and serviceability of reinforced concrete structures. address: kaunas university of technology, faculty of civil engineering and architecture, studentu st. 48, lt-51367, kaunas, lithuania. tel.: +370 37 300473 e-mail: sarunas.kelpsa@gmail.com mindaugas augonis – associated professor at kaunas university of technology, faculty of civil engineering and architecture, department of building structures. main research area: durability of engineering structures, strength and stability of reinforced concrete structures. address: kaunas university of technology, faculty of civil engineering and architecture, department of building structures, studentu st. 48, lt-51367, kaunas, lithuania. tel.: +370 37 300473 e-mail: mindaugas.augonis@ktu.lt mindaugas daukšys – associated professor at kaunas university of technology, department of civil engineering technologies. main research area: concrete mixture rheological properties, formed concrete surface quality. address: kaunas university of technology, faculty of civil engineering and architecture, department of civil engineering technologies, studentu st. 48, lt-51367, kaunas, lithuania. tel.: +370 37 300479 e-mail: mindaugas.dauksys@ktu.lt algirdas augonis – lecturer at kaunas university of technology, faculty of civil engineering and architecture, department of building materials. main research area: mechanical properties of building materials. address: kaunas university of technology, faculty of civil engineering and architecture, department of building materials, studentu st. 48, lt-51367, kaunas, lithuania. tel.: +370 37 300465 e-mail: algirdas.augonis@ktu.lt 13 journal of sustainable architecture and civil engineering 2015/1/10 journal of sustainable architecture and civil engineering vol. 1 / no. 10 / 2015 pp. 13-25 doi 10.5755/j01.sace.10.1.8801 © kaunas university of technology erika zaleskienė*, indrė gražulevičiūtė-vileniškė kaunas university of technology, department of architecture and urbanism studentu st. 48, lt-51367 kaunas, lithuania sébastien gadal aix-marseille université, cnrs, espace umr 7300 29 avenue robert schuman, 13621 aix-en-provence cedex 1, france *corresponding author: erika.brinkyte@gmail.com perspective of multiscale planning of rurban development: case of lithuania http://dx.doi.org/10.5755/j01.sace.10.1.8801 landscape planning as one of the most important spheres determining the lifestyle environment and the framework of the societal organisation, being a complex process dealing with hardly predictable future, numerous variables and interested parties, involves a high degree of uncertainty. dynamic, mutable and hard to define rurban landscapes emerging in the areas of rural-urban interface also imply a lot of uncertainty. these territories are a specific component and the indicator of the metropolisation as well. this means that planning of such landscapes is a difficult task requiring a distinctive approach. the aim of this research was to develop and present the rurban landscape planning principles. the approach to the rurban landscape planning and related research presented here can be identified as multiscale scientific sustainability-based: we have distinguished four major interrelated scales – global, regional, national, and local and analyzed aspects of uncertainty that should be evaluated and precautionary measures that can be taken, the research that should be carried out, the most relevant landscape sustainability dimensions, and the documents that must or can be employed at each scale. in order to illustrate the relevance and applicability of the presented approach it was illustrated with the case of lithuania. we have demonstrated the problems and challenges of landscape planning related to rural-urban interface in lithuania originating at global, regional, national, and local levels, relevant documents and recommended actions for more sustainable development of rurban areas in the overall context of landscape planning. the analysis has shown that the extensive juridical basis and the volume of other documents at all levels exist for successful planning and management of rurban areas in the country and the main problems causing contemporary failure to regulate the processes rural-urban interface are related with the lack of understanding or rurban problematic and the lack of understanding global, continental, and regional contexts, the lack of strategic integrated thinking, transparency, and competences in the planning process. keywords: rural-urban interface, rurban landscape, landscape planning, multiscale approach, lithuania. jsace 1/10 perspective of multiscale planning of rurban development: case of lithuania received 2014/10/03 accepted after revision 2015/02/12 journal of sustainable architecture and civil engineering 2015/1/10 14 introduction uncertainty the state of being unsure of something, unpredictability, doubt is an essential feature of contemporary life in many of its spheres and, as antrop (2004) notes, is characteristic to landscape change and planning i.e. the objects of this research. landscape planning a complex process and a complex of activities that aim to steer ongoing processes structuring our environment deals with a hardly predictable future, lots of variables, is accessible for many parties, both governmental and non-governmental and, consequently, implies a lot of uncertainty (antrop 2004, westerink et al. 2012). moreover, planning of rural-urban interface areas in particular means dealing with many sources and aspects of uncertainty simultaneously, as these territories themselves are the clear examples of uncertainty in and complexity of contemporary landscape and can be seen as the complex systems in the state far from equilibrium both with reference to urban or rural territory model or as the composites of contradictions (antrop 2004, jerpasen and swensen 2005, nilsson et al. 2008): delimitation between urban and rural becomes a fluid, relatively indistinct transition from what people would characterize as the city proper and the surrounding countryside (antrop 2004, jerpasen and swensen 2005); land zoning borders in these dynamic landscapes do not remain a stable delineation even for a short time (antrop 2004); rapid changes in land use extensively affect the character of natural and cultural historic landscapes (swensen and jerpasen 2008); landscape diversity, heterogeneity and fragmentation result in more complex forms of multifunctional land use (antrop 2004); unclear meaning of these areas: whether they are urban or rural, a platform for dynamics or the assets to be preserved, a production or a consumption landscape (westerink et al. 2012) etc. many factors, both non-local (musacchio 2009) and local, affect rurban landscapes, their development is determined at different scales from global to local, numerous research approaches and methods are needed in order to understand these landscapes, many documents of international, national or local significance can actually or potentially influence their planning and the lack of experience in planning and managing these emerging types of landscape is evident (musacchio 2009). the factor of uncertainty both in the field of landscape planning and the complexity and uncertainty embodied in the rurban landscapes themselves encourage to look for the planning approaches. the aim of this research is to develop and present rurban landscape planning principles and to illustrate their applicability using the case of lithuania. according to antrop (2004), uncertainty in landscape planning cannot be avoided, but the appropriate methods must be applied to deal with it and the precautionary principle is an adequate measure in this case. the precautionary principle states that an action should be taken when a problem or threat occurs, not after harm has been inflicted; it is an approach to decision-making, which justifies preventive measures or policies despite scientific uncertainty about whether detrimental effects will occur (world... 1998). the key elements of precautionary principle include: the anticipatory action to prevent harm, community’s right to know complete and accurate information on potential impacts, examination of the full range of alternatives including no action, full cost accounting when evaluating potential alternatives, transparent, participatory decision making informed by the best available science and other relevant information (wingspread... 1998, environmental... 2014). consequently the precautionary principle in rurban landscape planning under condition of uncertainty requires multiscale scientific sustainability-based approach in planning and related research ranging from global to local level and from abstract to very specific and concrete place-based information. the multiscale or multi-level principle is being extensively applied in landscape planning and research (rozenblat 2009, berte et al. 2013, city... 2014) and is implemented at the political and societal levels (jeffery 1997, tasan-kok and vranken 2011) the general term means pertaining to, or operating across multiple scales solving physical problems, which have important features at theory and methods 15 journal of sustainable architecture and civil engineering 2015/1/10 multiple scales, for example, spatial scales (geiser 2014). according to berte et al. (2013), multiscale processes in landscapes underpin both the natural and the social systems, which are based on multilevel relations. thus the rurban landscapes as socio-ecological systems (resilience... 2002, low choy and buxton 2011) or coupled human and natural systems (musacchio, 2009) are not an exception. with reference to berte et al. (2013) and antrop (2000) several important principles of multiscale systemic approach applicable to rurban landscapes can be distinguished: _ rurban landscapes change continuously under influence of “internal” (those that may be controlled at the local level urban settlement and its zone of influence) and “external” (influence on the local landscape conditions through upper level strategies and policies, for example, of national and supra-national levels) factors. _ decisions directly or indirectly influencing rurban landscapes are made on different hierarchical levels of policy-making (for example, from the global or the eu (european union) level to municipality or local place level) and manifest themselves in terms of actions at different levels (from changes in ideas and paradigm shifts (sustainability, precautionary principle etc.) to arrangements of lots in suburbs and infrastructure planning). _ multiscale processes work through connections, junctions, and linkages between the dynamics at different levels (for example, rural-urban interface problematics should be recognized at the global, regional, national levels, and so forth). according to vanempten (2009), “rurbanity also challenges policy-making concerning these areas, requesting an integrated rather than a sectorial approach and a regional perspective and scale for their redevelopment. the rurban reality therefore challenges contemporary urbanism to go beyond its classical boundaries and methods, to incorporate other disciplines, to play out its integrating role”. as the precautionary principle indicates, the actions at each scale (regional, national, local etc.) must be guided by the adequate scientific research, regulatory documents, and other relevant information (environmental... 2014). landscape research and its applications in planning use and combine very different scientific methods from natural to social sciences (antrop 2004); numerous research approaches and methods can be successfully applied at different levels, in different scales, for analyzing spatial, temporal and other aspects of rurban landscapes: landscape monitoring and analysis based on remote sensing, gis based approaches, for example, historic map overlay and historic landscape characterization, visual landscape characterization, aesthetic and ecological assessment, cultural and economic valuation, analysis of social significance etc. numerous international, regional, national, local level strategic, political and legal documents, research and management guidelines, reports, reviews, plans, feasibility studies and other material can and should also be used in planning and management of rurban landscapes. thus it is important to carry out the appropriate researches and to apply the appropriate guiding documents at the appropriate scale. in order to solve this question, the concepts of sustainability science research that produces useful knowledge and practical advice for highly complex problems (clark 2007, musacchio 2009) and landscape sustainability were applied. according to clark (2007), “sustainability science is a field defined by the problems it addresses rather than by the disciplines it employs” and focuses on the “understanding the complex dynamics that arise from interactions between human and environmental systems” and the “advancing understanding of coupled human-environment systems” in the “areas ranging from complex systems theory to cultural and political ecology”. musacchio (2009) noted that researches and practitioners working in the field of landscape research “have reinterpreted the definition of sustainable development to include the holistic basis of landscapes” and distinguished environment, economics, equity, aesthetics, experience, and ethics as the dimensions of landscape sustainability. considering the issues discussed above 1) uncertainty related with landscape planning and rurban journal of sustainable architecture and civil engineering 2015/1/10 16 landscape as a particular landscape type, 2) precautionary principle requiring anticipatory action, right to know, alternatives assessment, full cost accounting, and research based participatory decision process (environmental..., 2014), 3) multiscale approach to landscape research and planning, the ideas of 4) sustainability science and 5) landscape sustainability in the interrelated dimensions of environment, economics, equity, aesthetics, experience, and ethics (musacchio 2009), the approach towards rurban landscape planning and related research based on four major interrelated scales global, regional, national, local was developed. the outline of the approach is presented below and includes the short definition of each scale and the identification of the most important aspects regarding uncertainty, precautionary measures, sustainability science, landscape sustainability, and documents and measures at each of these scales: 1 global scale world scale, the whole of human civilization, experience, trends, ideas, non-local phenomena (musacchio 2009). uncertainty: outcomes of globalization, economic, social, environmental, urban dynamics at the global scale, emerging ideas and technologies, paradigm shifts. precautionary measures: anticipatory action, alternatives assessment, research based decision process. sustainability science: ideas and paradigms regarding humannature interactions, globalization, global phenomena of urbanization, metropolisation, urban sprawl, landscape and lifestyle changes, and climate change etc. landscape sustainability: the most relevant dimensions of landscape sustainability at this level are environment, economics, equity, experience, and ethics. documents and measures: international documents charters, conventions, documents, reflecting relevant experience of different regions and countries, feasibility studies and reports on social, demographic, economic, environmental, rural, urban etc. dynamics at the global scale, landscape and geographic monitoring systems, spatial analysis systems etc. 2 regional scale continental (for example, european scale of planning), supra-national regional level. uncertainty: economic, environmental and related urban dynamics at the regional scale, changes in landscape identity across regions, unclear social, economic and ecological outcomes of strategies and plans etc. precautionary measures: anticipatory action, alternatives assessment, full cost accounting, research based decision process. sustainability science: urbanization dynamics, economic flows, even or uneven development, identity of regions etc. landscape sustainability: the most relevant dimensions of landscape sustainability at this level are environment, economics, equity, experience. documents and measures: sustainability strategies and other strategic and political documents regarding urbanization, economic development, infrastructure, environment etc., directives, feasibility studies, reports of continental or regional level, landscape and geographic monitoring systems, spatial analysis systems etc. 3 national scale territory of the country. uncertainty: landscape transformations and urban dynamics at the national scale, changes in landscape identity, unclear social, economic and ecological outcomes of strategies and plans etc. precautionary measures: anticipatory action, alternatives assessment, full cost accounting, research based decision process. sustainability science: nature-human interactions at the national scale, urbanization dynamics at the national scale, even or uneven development of regions at the national scale, historic landscape character, national identity etc. landscape sustainability: the most relevant dimensions of landscape sustainability at this level are environment, economics, equity, experience. documents and measures: national sustainability strategies, various strategic plans of national level, master (general) plans of the territory of the country, feasibility studies, reports concerning national level, landscape and geographic monitoring systems, spatial analysis systems etc. 4 local scale encompasses different levels from the local place to the whole metropolitan area (city... 2014) including urban settlement/city and its influence zone, rurban territory 17 journal of sustainable architecture and civil engineering 2015/1/10 etc. uncertainty: landscape transformations at the local scale, multiplicity of stakeholders, conflicting interests, unclear aesthetic, social, economic and ecological outcomes of plans etc. precautionary measures: anticipatory action, right to know, alternatives assessment, full cost accounting, research based participatory decision process, particular attention should be paid at the right to know and participation. sustainability science: research on the interactions between urban settlement and surrounding natural and rural areas, between society and environment at the local level, questions of landscape fragmentation (ecological, aesthetic, social), multifunctionality, sustainability of communities, historic landscape character, local identity, environmental conditions, human health etc. landscape sustainability: at this scale all the dimensions of landscape sustainability environment, economics, equity, aesthetics, experience, and ethics become relevant, particular attention should be paid at environment, aesthetics and social issues. documents and measures: sustainability strategies, urban development strategies of the city and its zone of influence, feasibility studies, reports concerning local level, master plans, special plans, detailed plans, place concepts (westerink et al. 2012), landscape and geographic monitoring systems, spatial analysis systems etc. uncertainty is the particular feature of lithuanian landscape development and planning including the rapidly emerging rurban areas both because of the shifts from the centralized soviet urban planning to the present day situation and due to the non-control of the evolution according to the lifestyle changes and the liberalist economic trends. this encourages us to review problems and challenges of landscape planning related to rural-urban interface in lithuania and to illustrate the relevance and applicability of the above-presented approach with its case. the appropriate regulation of the process of urbanization and landscape sustainability and perceived quality is the basic premise for the development of healthy, aesthetic and ergonomic living, work, and recreational environment. in different countries these activities are developed in concept, legal, administrational, and territorial planning levels (kamičaitytė 2000, kamičaitytėvirbašienė 2003). kamičaitytė (2000), kamičaitytė-virbašienė (2003) carried out an extensive review how the process of urbanization and landscape visual quality, both very important for development of metropolitan areas, are regulated in different countries including france, italy, and spain. lithuania also has a body of strategic, political, legal, and territorial planning documents directly and indirectly influencing urbanization, landscape quality and the development of rurban landscapes from the national strategy of sustainable development (government of the republic of lithuania 2003, 2011) to master plans of urban settlements and detailed plans. kamičaitytė (2000) presents general scheme of regulation of urbanization process encompassing six steps: provisions of regulation of urbanization, legal basis, administration and planning, urbanization, monitoring, and evaluation of results (fig. 1). the last two stages systematic monitoring and assessment are very important in order to demonstrate the reality of territorial planning in lithuania in the context of rural-urban interface and to develop adequate recommendations. however, no official systematic monitoring of urban dynamics is carried out at the present day in lithuania (bardauskienė and pakalnis 2010). consequently the review of the present situation was based on the territorial planning documents, existing scientific researches and reviews including pakalnis (2010), bardauskienė and pakalnis (2010, 2012), pakalnis and bardauskienė (2012), čereškevičius (2012), cirtautas (2012), gadal (2011, 2012), ramanauskas and dringelis (2011, 2013), vanagas and neniškis (2000), ongoing changes in landscape and our own observations. the problems and challenges of landscape planning related to rural-urban interface originating at different levels distinguished in the previous section global, regional, national, local relevant documents and recommended actions for more sustainable development are presented below. results journal of sustainable architecture and civil engineering 2015/1/10 18 1 global scale. prob-lems: different trends and ideas affect contemporary landscape planning and management of rural-urban interface and related research around the world including the ideas presented above (socio-ecological systems and resilience of such systems (resilience... 2002, low choy and buxton 2011), precautionary principle, development of contemporary cultural landscapes (berte et al. 2013), ecoaesthetics, holistic, integrated approach towards landscapes, multiscale approach to planning) as the answers and reacfig. 1 general scheme of regulation or urbanization process demonstrating the importance of systematic monitoring and assessment of results redrawn and translated from kamičaitytė (2000) tions to contemporary global environmental, aesthetic, economic and other challenges. many of these ideas have originated as a part of sustainability science and are linked with the general idea of sustainable development. even if lithuania has the official national strategy of sus tainable development declaring that strategic priorities and principles of the country’s sustainable development reflect lithuanian interests, peculiarities, the priorities of the renewed eu sustainable development strategy and other programmatic documents and lithuanian landscapes, including the areas of rural-urban interface, are affected by such global trends as metropolisation, industrialization, commercialization, uniformity, it is possible to state that the principles of sustainability still are not integrated into the territorial planning (ramanauskas and dringelis 2013) and are not visible in actual development of the rurban areas. according to bardauskienė and pakalnis (2010), it is difficult to evaluate the correspondence of contemporary landscape and urban dynamics of the country to the principles of the national strategy of sustainable development as no systematic monitoring and evaluation of urban development are carried out; however, the contemporary landscape reality demonstrates basic discrepancies, the more detailed analysis of which is presented below at the lower regional, national, local levels. actions: integration of the global experience, advances and paradigms corresponding country’s interests, peculiarities, and identity into the territorial planning and their systematic application to rurban areas. documents: paradigmatic documents: our common future (world commission on environment and development 1987), wingspread statement on the precautionary principle (1998), riodeclaration, agenda 21 (united nations conference on environment and development 1992), johannesburg declaration on sustainable development and johannesburg plan of implementation (world summit on sustainable development 2002) etc. sectorial documents important to rurban areas: charter of new urbanism (the congress for the new urbanism 1996) regarding polycentric multifunctional development of rurban areas, burra charter (australia icomos (international council on monuments and sites) 1979, 2003), charter on the interpretation and presentation of cultural heritage sites (icomos 2008) regarding cultural significance and interpretation of rurban landscapes, international charter for the conservation and restoration of monuments and sites (2nd international congress of architects and technicians of historic monuments 1964.), 19 journal of sustainable architecture and civil engineering 2015/1/10 historic gardens charter (icomos 1981), charter on the built vernacular heritage (icomos 1999) regarding rural heritage in rurban areas etc. 2 regional scale. problems: the competition of urban settlements in the continental, regional and even in the global context is the new reality that lithuanian urban development policy has to face (cirtautas 2012) together with the integration into the european, baltic sea region organizations and that affects rural-urban interface processes. researchers analyzing the problematics of country’s spatial development in the regional scale (vanagas and neniškis 2000, vanagas 2003, gadal 2011, 2012, cirtautas 2012) identify the lack of contextualization and insufficient interest in the potential of spatial organization of lithuanian territory and cities in the international context (vanagas and neniškis 2000), the absence of integrated territorial politics linked to the economic development and of real development policy at the national and regional levels (gadal 2011, 2012). according to vanagas and neniškis (2000), the collapse of the planned urbanization system of the soviet era, the period of geopolitical reorientation resulted in ignoring the international context and international territorial systems and lithuania being seen solely as a transit country; the policy of even regional development of the soviet period in this new reality is even seen as a shortcoming and the possibility to increase the potential of lithuanian cities by creating bipolar structure tandem of two cities is discussed (vanagas and neniškis 2000, vanagas 2003). the geopolitical reorientation and the emphasis on large urban structures, the process of metropolisation are changing and will change in the future the problematics of rural-urban interface in the country. actions: integration of the continental and regional experience, advances, ideas and provisions of documents corresponding country’s interests, peculiarities, and identity into the territorial planning and their systematic application to rurban areas, contextualization of territorial planning taking into account the situation including communication routes and urban dynamics in the continent and in the baltic sea region, development of more active territorial and spatial strategy in the regional context (vanagas and neniškis 2000) taking into account contemporary socioeconomic and geopolitical realities and lithuanian experience of even regional development, understanding the role and potential of lithuanian urban settlements in the continental network of cities, examination of the full range of urban dynamics alternatives and full cost accounting when evaluating potential alternatives in the regional context. documents: european level paradigmatic and sectorial documents: renewed eu sustainable development strategy and related documents, european landscape convention (council of europe 2000), european spatial development perspective (european commission 1999), the cork declaration (the european conference on rural development 1996), urban sprawl in europe, the ignored challenge (european environment agency report 2006), leipzig charter on sustainable european cities (council of ministers 2007), pan-european biological and landscape diversity strategy (3rd ministerial conference “an environment for europe” 1995) etc. eu directives: environmental impact assessment directive, strategic environmental assessment directive, environmental liability directive, habitats directive, urban waste water directive etc. regional initiatives: wismar declaration on transnational spatial planning and development policies for the baltic sea region (conference of ministers responsible for spatial planning and development in the countries of the baltic sea region 2001) and other initiatives by vasab (visions and strategies around the baltic sea) intergovernmental multilateral co-operation of 11 countries of the baltic sea region in spatial planning and development, guided by the conference of ministers responsible for spatial planning and development, steered by the committee on spatial planning and development of the baltic sea region composed of representatives of respective ministries and regional authorities (visions... 2014). 3 national context. problems: legal documents regulating urban dynamics, rural and regional development in the country change and are constantly amended. recently adopted journal of sustainable architecture and civil engineering 2015/1/10 20 new law on territorial planning and related documents (2013, 2014) integrate some advances of territorial development, including notion of sustainability, complex (integrated) territorial and spatial development, multifunctionality etc. however, the post-soviet transition process, legislation changes and the lack of consistent approach condition that currently the actual territorial and spatial development does not follow strategies and plans including the goals of sustainability (ramanauskas and dringelis 2013) there is a dichotomy between the reality of urbanisation and urban development plans implemented by municipalities or the state (gadal 2011) and this situation is clearly reflected in the areas of rural-urban interface surrounding largest cities of the country. contemporary urbanisation is guided by liberalism and the reality of spatial dynamics of metropolisation and urbanisation and de facto existing urban metropolitan regions still are not recognized by the state (gadal 2011, cirtautas 2012). the well-known case of vilnius-kaunas dipolis (vanagas and neniškis 2000, vanagas 2003) demonstrates the contradictions between the theoretical ideas and the actual processes, as both cities extend into opposite direction (gadal 2011). another example is land restitution and unregulated privatisation of land after the collapse of the soviet regime regardless of master plans (ramanauskas and dringelis 2013), which became one of the reasons of unregulated development of rural-urban interface areas. in fact, the researches (bardauskiene and pakalnis 2010, pakalnis 2010; čereškevičius 2012, cirtautas 2012, ramanauskas and dringelis 2013) and landscape reality demonstrate the paradoxical situation the territorial planning often follows development and interests. according to pakalnis (2010), in public realm the territorial planning is controversially perceived as a chain of procedures aimed at legalizing certain activities, as a means to realize of hinder certain development projects. trends and scale of development of some urban settlements envisioned in planning documents are not objectively determined by the logics of urban dynamics but adjusted to the needs of the politicians of local municipalities and the influential business interests standing behind (čereškevičius 2012). this lack of competence and transparency determined the deregulation of urban expansion and the disproportionate influence of market forces and private capital in the contemporary urban development (cirtautas 2012, ramanauskas and dringelis 2013) especially in rurban areas. another aspect determining unregulated and ineffective urban planning identified by pakalnis (2010) is the dominance of sectorial influence (environmental protection, creation of favorable conditions for economic activities, heritage preservation etc.) over the general integrated goals of master and detailed plans. actions: improvement of planning and landscape management competences. development of complex policy of urban, rural, and regional development and overall vision of country’s spatial development (bardauskienė and pakalnis 2010) integrating anticipatory action, alternatives assessment, full cost accounting, research based decision making process, understanding of rurban problematics and incorporation of related concepts into legal documents. sectorial interests must be integrated in and coordinated (pakalnis 2010) by the common vision of rural and urban development. urban dynamics, rural-urban interface, rural development, development of country’s regions must be systematically monitored and evaluated at the national level. national level institutions should be actively involved in the development of master plans (bardauskienė and pakalnis 2010). documents: strategic documents: strategy of long-term development of the country (seimas of the republic of lithuania 2002), strategy of lithuanian regional policy (government of the republic of lithuania 2005), national strategy of sustainable development, lithuanian strategy of environmental protection (ministry of environmental protection of the republic of lithuania 1996), national strategy of rural development (ministry of agriculture of the republic of lithuania 2007) etc. political and program documents: landscape policy of the republic of lithuania (government of the republic of lithuania 2004), architecture policy of the republic of lithuania (government of the republic of lithuania 2005), program of regional development of the republic of lithuania (government of the republic of lithuania 2006) etc. laws: law on land reform (1991, 2013), law 21 journal of sustainable architecture and civil engineering 2015/1/10 on regional development (2002), law on territorial planning and related documents (1995, 2013, 2014), law on protected areas (1993, 2001), law on immovable cultural heritage (1994, 2004), law on the land (1994, 2004), law on forests (1994, 2001), law on construction (1994, 2014), law on green areas (2007) etc. territorial planning documents of national scale, for example, master plan of the territory of the republic of lithuania. research reports, feasibility studies, resolutions; for example, the resolutions of the urban forums each year organized by the ministry of environment and other institutions. the urban forum of 2010 was dedicated to rural-urban interface. 4 local context. problems: the prospects of urban development acquire the juridical basis through the solutions of master plans (čereškevičius 2012). the local level territory of municipality, urban settlement, segments of the rurban areas clearly demonstrates the shortcomings of the territorial planning and of the development of the rurban areas in lithuania. according to bardauskienė and pakalnis (2010), cotemporary master plans of urban settlements fail to balance the socio-demographic trends and the desire of municipalities to create new territories for investment. in the context of rural-urban interface this means the development and expansion of urbanization into rural and natural areas being uncoordinated with the overall development of the city. official statistics demonstrates that the overall number of inhabitants and the urban population in lithuania is constantly decreasing. according to čereškevičius (2012), in almost all country’s urban settlements with the population over 10 000 the number of inhabitants has decreased in the period of 1989-2011, the future prognosis is also threatening. meanwhile, the master plans for the cities prepared during 2005-2010 envision the population increase from 1.5 to 15.4 percent in these urban settlements. this ungrounded theoretical increase in the urban population is reflected in the territorial planning solutions the average increase of the territories of the cities in these plans is 44.7 percent (čereškevičius 2012); for example, the master plan of vilnius city adopted in 2007 envisions the territory of 3000 hectares for new development (bardauskienė and pakalnis 2010, rimkutė 2011); the region of kaunas is characterized by a strong process of suburbanization and rurban dynamics in the demographic context of population decline (gadal 2011). such evident imbalance between the demographics and new territories intended for urbanization in the master plans combined with the abovementioned dominance of market forces and business interests reflected in the development of built fabric, when detailed plans are prepared solely for the small lots of developers or builders without the wider context, inevitably creates scattered low density urban sprawl chaotically transforming agricultural territories into suburban residential areas without clear and legible urban structure, public spaces and corresponding infrastructure (bardauskienė and pakalnis 2010, pakalnis 2010, ramanauskas and dringelis 2011, 2013, cirtautas 2012) with all the negative consequences on landscape identity, environment, cultural heritage, agriculture, urban composition and aesthetics etc. moreover, the master plans of the municipality of the city and of the municipality of the surrounding district often are not coordinated as the research of ramanauskas and dringelis (2013) well demonstrates with the case of kaunas city and kaunas district master plans which envision more new built up areas than currently exist. another important issue in territorial planning in general and in development of rurban areas in particular is public participation. according to jakaitis (2005), pakalnis (2010), despite the numerous procedures of publicity and public participation in territorial planning guaranteed by the legislation of the country, society, due to its passivity or due to complicated planning procedures, is not aware of the decisions made by the institutions and their influence on the quality of life. ruralurban interface areas with low population density, characteristic social conflicts and conflicts of interests constitute a particular challenge for participatory decision-making. in fact the scattered urbanized islands in rural or natural landscape in the rurban areas are often planned solely based on the short-term economic efficiency criteria relevant to the developer. journal of sustainable architecture and civil engineering 2015/1/10 22 actions: in the multiscale planning of rurban development the most important is supporting the local context under a multiscale perspective (berte et al. 2013). in this local scale, where the character, identity, functionality, environmental sustainability of rurban areas is revealed, all the precautionary measures anticipatory action, right to know, alternatives assessment, full cost accounting, research based participatory decision process should be implemented. several important actions that can be implemented through the legislation and territorial planning documents should be mentioned: coordination of planning documents (for example, master plans of the municipality of the city and of the municipality of surrounding district) in order to control the territorial urban expansion and unnecessary development of infrastructure compact, “brown” urbanism (bardauskienė and pakalnis 2010, pakalnis and bardauskienė 2012), priority of integrated vision, image of the rurban area over the sectorial interests (pakalnis 2010), integration of rural vernacular settlements and relicts of rural landscape in rurban areas (costa and batista 2011), application of functioning mechanisms of consolidation of properties and land acquisition to the public needs for development of multifunctional, polycentric rurban areas with necessary infrastructure, legible urban structure and public areas (ramanauskas and dringelis 2011) and optimizing qualitative and quantitative parameters of existing and new structures (čereškevičius 2012) in rurban areas (researches demonstrate that investments in infrastructure are ineffective if density is lower than 30 residents per hectare (bardauskienė and pakalnis 2010)). at this level particular attention should be paid at the development of communities and their participation in decision making. the research by jakaitis (2005) demonstrates that public participation is more effective using not only compulsory but also informal means including forums, lectures, seminars and should start at the stages of visions and concepts. this is important in the rurban areas, where numerous social conflicts and conflicts of interests emerge. another of his findings that the efficiency of public participation is directly depending on the degree of polycentricity of the urban area and inversely dependent on the level of abstractness of territorial planning goals also demonstrates the need of polycentric rurban development resulting not only in qualitative and efficient urban structure, but also in active communities and the importance of participation in the local level, especially concerning the development of particular residential segments of rurban areas. documents: strategic documents: strategies of development of particular urban settlements or regions. territorial planning documents: master plans of municipality territory and its parts, detailed plans, special plans of municipality territory and its parts (for example, land management schemes, rural development projects, plans for development of engineering infrastructure, plans of protected areas etc.). projects: construction projects, projects of green areas etc. other documents: development programs, feasibility and scientific studies, reports concerning local level. 1 planning problematic. landscape planning as a future-oriented activity targeted at such a complex entity as landscapes involves a lot of uncertainty. rurban landscapes themselves being hardly definable and unstable and their development, which is affected by many nonlocal and local factors and determined at different scales from global to local, can be also characterized with the term “uncertainty”. the factor of uncertainty both in the field of landscape planning and the complexity and uncertainty embodied in the rurban landscapes encourage to look for new comprehensive planning approaches for these landscapes. 2 theoretical approach. the research has demonstrated that the uncertainty related with landscape planning and embodied in rurban landscape as a particular landscape type requires the precautionary principle and the application of the advances of sustainability science in the interrelated dimensions of environment, economics, equity, aesthetics, experience, and ethics at the multiple interrelated scales. thus our approach to the rurban landscape planning conclusions 23 journal of sustainable architecture and civil engineering 2015/1/10 antrop m. 2000. background concepts for integrated landscape analysis. agriculture, ecosystems and environment, 77, 17-28. http://dx.doi. org/10.1016/s0167-8809(99)00089-4. antrop m. 2004. uncertainty in planning metropolitan landscapes. in: tress g., tress b., harms b., smeets p., van der valk a. planning metropolitan landscapes. concepts, demands, approaches, 12-25. bardauskienė d., pakalnis m. 2010. planavimo dekadansas ir plėtros valdymo šansai. 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(accessed 13 october 2014). vanagas j. 2003. miesto teorija. vilnius, vilniaus dailės akademijos leidykla, 247. vanagas j., neniškis e. 2000. lietuvos miestų potencialas baltijos jūros regiono urbanistiniame kontekste. urbanistika ir architektūra, 24(2), 47-59. vanempten e. 2009. challenging urbanism: the rurban reality of the brussels metropolitan area. university of leuven. available at: https://lirias. kuleuven.be/bitstream/123456789/258777/1/el25 journal of sustainable architecture and civil engineering 2015/1/10 erika zaleskienė phd student department of architecture and urbanism, faculty of civil engineering and architecture, kaunas university of technology main research area formation of green areas, rural-urban interface, rurban landscapes address studentu st. 48, lt-51367 kaunas, lithuania, tel. +370 37 451 546 e-mail: erika.brinkyte@gmail.com indrė gražulevičiūtėvileniškė associated professor department of architecture and land management, faculty of civil engineering and architecture, kaunas university of technology main research area preservation and management of built heritage, application of principles of sustainability to architecture and landscape, rural-urban interface, rurban landscapes address studentu st. 48, lt-51367 kaunas, lithuania tel. +370 37 451 546 e-mail: indre.grazuleviciute@ktu.lt sébastien gadal prof. habil. dr. aix-marseille université, cnrs, espace umr 7300 main research area metropolisation, territorial development, socio-environmental impacts, urban spatial monitoring systems by remote sensing, gis, and simulation address 29 avenue robert schuman, 13621 aix-en-provence cedex 1, france e-mail: sebastien.gadal@univ-amu.fr about the authors ke+vanempten_u&u_rurban+brussels_2009.pdf (accessed 09 april 2014). visions and strategies around the baltic sea. 2014. available at: http://www.vasab.org/index.php/ about-vasab (accessed 17 april 2014) westerink j., lagendijk a., du¨hr s., van der jagt p., kempenaar a. 2012. contested spaces? the use of place concepts to communicate visions for peri-urban areas. european planning studies, 1–21. wingspread conference on the precautionary principle. 1998. available at: http://www.sehn.org/ wing.html (accessed 10 april 2014). world english dictionary. 1998. precautionary principle. available at: http://dictionary.reference. com/browse/precautionary+principle (accessed 09 april 2014). 60 darnioji architektūra ir statyba 2014. no. 2(7) journal of sustainable architecture and civil engineering issn 2029–9990 recycled aggregate concrete as material for reinforced concrete structures marta kosior-kazberuk1*, mateusz grzywa2 1*bialystok university of technology, faculty of civil and environmental engineering, wiejska str. 45e, 15-351 bialystok, poland. 2fcum, technical department, okolnik str. 2, 00-368 warsaw, poland. *corresponding author: m.kosior@pb.edu.pl http://dx.doi.org/10.5755/j01.sace.7.2.7135 processing crushing concrete into coarse aggregate for the manufacturing of new concrete is one common means for achieving more environmentally friendly concrete. the use of recycled aggregate from construction and demolition waste as replacement of natural aggregate has increased in recent years in order to reduce the high consumption of natural resources by civil engineering. in the research work an experimental investigation was carried out to analyze the influence of steel fiber reinforcement on the load-strain behavior of beams made of recycled aggregate concrete. in addition, the selected properties of recycled aggregate were assessed and the strength properties of concretes were also determined. the concretes tested contained natural fine aggregate and 100 % recycled coarse aggregate. the flexural behavior was tested on model reinforced concrete beams. apart from reinforcing steel bars, the steel fibers with 6 mm length and aspect ratio of 37,5 were used in a volume fraction of 0,52 %. the results showed that the addition of steel fiber and recycled aggregate increased the mechanical strength and modified the flexural behavior and fracture process relative to that of recycled aggregate concrete. keywords: recycled aggregate, reinforced concrete beam, steel fibre, waste management. 1. introduction according to the concept of sustainable development, the environmental load of a building must be evaluated throughout its life cycle, from design to construction, maintenance or repair, demolition and rubble disposal (van loo 1998). therefore, from a holistic point of view, sustainable construction means designing a reinforced concrete structure with appropriate durability during a specified service life. among the possible solutions favoring greater environmental sustainability in the construction industry, material engineering is considering the use of recycled aggregates from building demolition to produce new concrete. decreasing natural resources of sand and gravel and increasing problems with waste management support the recycling of the accumulating waste materials. if the vision of a sustainable material flow is to be realized, the amount of recycled waste has to be increased. the building industry in particular is a major consumer of materials and, at the same time, a major producer of waste. one possibility is to recycle and reuse inorganic building waste as concrete aggregates (marie and quiasrawi, 2012; chen et al., 2003). the use of waste from the demolition of concrete structures as aggregate in concrete has been widely studied and practiced for many years in developed countries (corinaldesi and moriconi, 2009). from the beginning, the main idea was the disposal of concrete waste in order to gain valuable raw material and thus the protection of natural aggregate sources according to sustainable development rules. over the last decades the significant number of experimental works has been carried out to investigate the material properties (ajdukiewicz and kliszczewicz, 2002; gonzález-fonteboa and martínez-abella, 2008; cabral et al., 2010) and durability (levy and helene, 2004, gokce et al., 2011; lovato et al., 2012) of recycled aggregate concrete. compared to natural aggregates, recycled aggregates usually have greater porosity and water absorption, lower density and lower strength than normal aggregate (marinković et al., 2010, hoffmann et al., 2012). as a result, rac structural members invariably experience inferior physical and mechanical properties compared to normal aggregate concrete, such as low mechanical performance and poor durability behavior (richardson et al., 2011, kou and poon 2012). for concrete made with 100 % recycled aggregate, the compressive strength reportedly decreased by 9–40 % (tabsh and abdelfatah, 2009). according to casuccio et al. (2008) and fathifazl et al. (2009) the lower elastic 61 modulus of rac is attributed to lower modulus of elasticity of recycled aggregate, and lower strength of rac is mainly due to the weaker mortar as well as the weaker interfacial transition zone (itz) between the old mortar and new mortar. recycled aggregate concrete (rac), which is used mainly for nonstructural purposes (aggregates in granular base or sub-base applications, for embankment construction and earth construction works), has the potential to be applied over a broad range of structural member types, based on the examples of structural behavior (behavior under flexural conditions, shear, bond, compression, etc.) presented by xiao and falkner (2007), carneiro et al. (2014), letelier gonzalez and moriconi (2014), wang et al. (2013). however, still very few investigations have been performed in the field of structural behavior of rc members. available experimental data concerning the concrete made with recycled aggregate are highly variable since the quality of rac mostly depends on the quality of original demolished concrete used for recycling (ajdukiewicz and kliszczewicz, 2002; etxeberria et al., 2007). in addition to the fluctuation in the composition of recycled aggregates, the lack of knowledge concerning the structural behavior of members with rc is another factor limiting their use in construction. although the use of construction and demolition waste as recycled aggregate in substitution of natural aggregate has been proved to be a good solution to minimize consumption of natural resources (eguchi et al., 2007; breccolotti and materazzi, 2010), the structural behavior of the recycled aggregate concrete is not yet fully understood and its use in structural applications is limited by european (din 4226-100, 2000) and japanese (bcsj 1977) standards. over the past several decades, steel fiber reinforced concrete has been used in many applications such as concrete pavements, overlays, patching repair of hydraulic structures, thin shells and precast products (bentur and mindess 1990). nowadays, it is well established notion that the incorporation of steel fibers improves engineering performance of structural and nonstructural concrete, including better crack resistance, increase in ductility and toughness (caneiro et al., 2014). there were the trials to combine the steel fibers with ordinary reinforcement in concrete members (andriušis et al., 2013) it is well known that the mechanical properties of steel fiber reinforced concrete depend on the aggregate type and matrix strength (balendran et al., 2002). however, there is the lack of data regarding the mechanical behavior of steel fiber reinforced concrete with recycled aggregate. the recent data in the literature (eguchi et al., 2007; exteberria et al., 2007; xiao and falkner, 2007) have shown that the use of relatively low amounts (up to 30 % of total amounts) of recycled aggregate does not substantially affect the concrete properties. considering the effective utilization of waste materials for better environmental preservation, the searching of ways for the increase in recycled aggregate content in concrete is highly recommended. the research programme concerned the concrete with the high content of recycled aggregate, it means that total volume of coarse aggregate was replaced by recycled aggregate. according to chen et al. (2003) and casuccio et al. (2008) the rough surface texture of recycled aggregate permits good mechanical interlocking between grains and cement matrix due to some penetration of cement paste into the open surface pores in the coarse aggregate particles. the study discusses the experimental results for the behavior of concrete beams composed of recycled aggregate and steel fibre. the four-point bending test was conducted subsequently to investigate the flexural behavior of the model beams exposed to sustained load. the selected properties of recycled concrete and strength properties of concretes were also determined. 2. methods 2.1. materials the commercial portland cement cem i 42.5 r according to en-197-1 (2011) was used. selected physical and chemical properties of cement are presented in table 1. tape water was used in all mixtures. fine quartz sand (0–2 mm) with density 2620 kg/m3 was used as natural fine aggregate. the construction and demolition waste, from reinforced concrete pre-caste elements, used in the experiment, were initially crushed using a jaw crusher. the pollutions and steel remains were removed. then, the material was sieved to produce the recycled aggregates of two fractions: 2–4 mm and 4–8 mm, characterized by density 2410 kg/ m3 and 2475 kg/m3, respectively. the aggregate used was processed in a laboratory. the straight steel fibers (dramix hi perform) in a volume fraction 0.52 % (40 kg/m3) with 6 and 0.13 mm of length and diameter, respectively, were used. in order to improve the steel fibers distribution in the concrete mix, the polycarboxylates based superplasticizer was used. table 1. physical and chemical properties of the portland cement property cem i 42,5 blaine surface (cm2/g) 3800 initial set time (min) 160 final set time (min) 220 compressive strength (mpa) 2 days 28.0 28 days 52.0 chemical components (%) so3 2.87 cl0.08 loss on ignition (%) 1.64 insoluble parts (%) 0.77 soundness (mm) 0.90 2.2. mix proportions and specimen preparation the concretes tested contained 100 % natural fine aggregate (0–2 mm) and 100 % recycled coarse aggregate (2–8 mm). the maximum diameter of coarse aggregate was limited considering the sizes of model rc beams. plain concrete (rac) and steel fiber concrete (frac) were produced. the steel fibers were introduced into concrete mix replacing the part of coarse aggregate in volume (0.52 %). the content of steel fibers was determined considering the 62 optimal content for reinforced concrete elements (bentur and mindess 1990). both concretes were manufactured with the same water to cement ratio (w/c=0.50). table 2 presents the mix proportions and selected properties of fresh concrete. the density of fresh concrete was assessed according to en 12350-6:2009 and the slump flow class was controlled according to en 12350-5:2009. natural and recycled aggregates were used in surfacedried condition. for each type of aggregate, the total moisture content was determined immediately before the mixing procedure. table 2. mix proportions for concretes used and selected properties of fresh concretes component/property rac frac cement (kg/m3) 350 350 water (kg/m3) 175 175 fine aggregate 0–2 mm (kg/m3) 755 755 coarse aggregate 2–4 mm (kg/m3) 424 423 coarse aggregate 4–8 mm (kg/m3) 616 615 steel fibers (kg/m3) – 40 superplasticizer (kg/m3) 2 6 density (kg/m3) 2280 2300 flow class (-) f3 f4 the concrete mixtures were produced using laboratory mechanical mixer. a two-stage mixing approach was used. the following sequence of mixing was applied: addition of the coarse aggregate, addition of 70 % water with superplasticizer, addition of cement and fine aggregate, addition of remaining water. when steel fibers were introduced, they were added with coarse aggregate. the mixing time of 10 min was used to guarantee the homogeneity of the concrete. the cube specimens sized 150 × 150 × 150 mm for compressive strength, beam specimens sized 100 × 100 × 400 mm for flexural strength. every series consisted of six replicates. the model recycled concrete beams (80 × 120 × 1100 mm) were used to analyze the flexural behavior under sustained load. the beams had various reinforcement ratios equal 1 % (3 bars ø 6 mm), 1,5 % (2 bars ø 8 mm and 1 bar ø 6 mm) and 2 % (2 bars ø 8 mm and 1 bar ø 10 mm). the reinforcing bars of steel bst 500s were used. stirrups of 3 mm diameter were applied. all of the rc beam specimens were designed in accordance with en 1992-1-1 (2004) and were ensured for flexural failure for testing. three series of plain recycled aggregate concrete and three series of recycled aggregate concrete with steel fibers were tested. every series consisted of three replicates. all concrete specimens were cured in water at 20 ± 2 oc until the time of testing. one day before the proper test the specimens were air-cured in the laboratory environment. 2.3. test methods the experimental programme was divided into three phases: recycled aggregate testing, concrete properties testing and testing the flexural behavior of model concrete beams. aggregate properties tests included water absorption (en 1097-6:2013), loose bulk density (en 1097-3:2000) and aggregate particle shape (en 12620:2013). concrete tests consisted of compressive strength fc,cube testing at 7, 14 and 28 days (en 12390-3:2009 and en 12390-4:2000) and flexural strength fm determined in three point bend test at 7, 14 and 28 days (en 12390-5:2009). for flexural behavior analysis the simply supported specimens were investigated under four-point bend conditions using universal testing machine. the net span length l (fig. 1) was 1000 mm. the load was applied to the failure with displacement control at a rate of 0.05 mm/s. the automatic system for data acquisition was used to measure the deflection in the mid-span and the strain in the tensile reinforcement and compressive concrete. fig. 1. the way of load of rc specimen during test 3. results and discussion 3.1. properties of recycled aggregate the tests were performed on the coarse recycled aggregate. the aggregate fraction 2–4 mm and 4–8 mm were characterized by loose bulk density 1280 kg/m3 and 1340 kg/m3, respectively. the loose bulk density of quartz sand was 1640 kg/m3. the water absorption of recycled aggregate (2–8 mm) after 2 hours was 9.27 % and after 24 hours – 11,05 %. the absorption of natural aggregate (0–2 mm) was 2.2 %. the texture of recycled aggregate is rougher due to the adhered mortar, thus it presents higher water absorption and lower density than natural aggregate. the particle shape analysis showed relatively small part of irregular shape grains in coarse aggregate – 2 % of total mass. the recycled aggregate meets the standard requirements for aggregate used in concrete (en 12620:2013). it is obvious that the recycled aggregate has similar particle shape as the crushed rocks used in normal concrete (chen et al., 2003). the method of recycled aggregate production has a crucial influence on the proper particle shape. 3.2. properties of hardened concrete the strength properties development in time of recycled aggregate concrete with and without steel fibers were analyzed. both concretes were classified to c35/45 strength class. the mean values of compressive strength 63 fc,cube as well as the standard deviation values δf are reported in table 3. table 3. compressive strength development – mean values fc,cube and standard deviation δf concrete type compressive strength after n days (mpa) 7 days 14 days 28 days fc,cube δf fc,cube δf fc,cube δf rac 34.9 2.91 39,7 1.47 45.7 1.60 frac 35.8 1.53 41.8 1.82 47.6 2.81 the high surface roughness of recycled aggregate leads to a good bond between cement paste and aggregate and thus allows gaining the strength properties suitable for concrete structures. the addition of steel fibers slightly influenced the compressive strength. however, the presence of fibers had an effect on the failure mode of specimens made of concretes tested (fig. 2). the concrete specimens with fibers kept their shape under destructive load. fig. 2. failure mode of specimens during compression: plain recycled aggregate concrete (left side), fiber reinforced recycled concrete (right side) the mean values of flexural strength fm as well as the standard deviation values δf are reported in table 4. the flexural strength increased with increasing compressive strength. the significant difference in the relation between the compressive strength and flexural strength for rac and frac was observed. the steel fibers improved the flexural strength of frac. table 4. flexural strength development – mean values fm and standard deviation δf concrete type flexural strength after n days (mpa) 7 days 14 days 28 days fm δf fm δf fm δf rac 5.8 0.09 6.5 0.12 6.6 0.17 frac 5.5 0.08 6.3 0.08 7.4 0.14 concerning the standard deviation values of strength properties, they were practically independent from the type of concrete, showing that the steel fibers had no influence on the homogeneity of concrete mixtures. 3.3. flexural behavior of rc members made of recycled aggregate concrete the model beams were tested in four-point bend test condition. beam load, deflections, reinforcing bars strains and concrete strains were monitored. the mean values of deflection measured in the mid-span of the rac and frac beams are presented in fig. 3 and 4, respectively. it is well known that the deflection depends on the longitudinal reinforcement ratio. however, the differences in load-deflection relationships, in considered range of reinforcement ratios, were greater for concrete with addition of steel fibers. the areas under the load-deflection curves for concrete members with fibers (frac) were significantly greater than for concrete members without fibers (rac). thus, the destruction of fiber reinforced beams required greater amount of energy. similar results were obtained by casuccio et al. (2008). the model beams with steel fibers under maximum load did not destroy suddenly, but the process run smoothly. the destroyed members kept their shape. the quasi-plastic behavior was an effect of fibers interaction with cement matrix. the fibers improved concrete members resistance to deformation. it was confirmed by the results of the maximum load measurement for particular beam series (table 5). comparing the load bearing capacity of recycled aggregate concrete beams with and without steel fibers, it was found that the fibers had an effect on the dynamics of the capacity increase. table 5. maximum load values for concrete beams tested with different reinforcement ratio concrete type maximum load (kn) 1 % 1,5 % 2 % rac 33.2 (100 %) 42.8 (129 %) 53.0 (160 %) frac 33.1 (100 %) 44.9 (136 %) 57.2 (173 %) fig. 3. load versus deflection in the mid-span for rac model beams with various reinforcement ratios 64 fig. 4. load versus deflection in the mid-span for frac model beams with various reinforcement ratios the load-strain curves obtained for rac and frac members with various reinforcement ratios are presented in fig. 5 and 6, respectively. comparing the shape of the curves, it can be noted that although the constitutive relationships are not identical, they have a similar pattern at pre-peak zone. the recycled aggregate may influence the failure mode of beam under flexure. in concrete with recycled aggregate the cracks can propagate both through the cement paste (interface zone) and through the aggregate due to the presence of grains with lower strength and stiffness. in these aggregates tensile stresses occurring at the tip of the grain and the high levels of tangential stresses that may occur in the matrix close to the interface and aggregate surface may affect the fracture process of the concrete. the strains in tensile zone decreased with the increase in reinforcement ratio. fig. 5. load-strain curves for rac model beams under flexural load fig. 6. load-strain curves for frac model beams under flexural load the steel fibers had an effect on the limitation of deflection and the strains’ values in both compressive and tensile zones of beams, making the concrete more ductile. the addition of steel fiber to recycled aggregate concrete improved its mechanical performance due to the greater resistance to sliding of pre-existing microcracks and by reduction of wing-cracks growth rate due to crack bridging. the presence of fiber had a positive effect to restore the level of crack initiation stress of concrete. 4. conclusions both the mechanical properties of recycled concrete were studied and the physical properties of recycled coarse aggregate were studied. the flexural behavior was analyzed on model beams made of concrete containing recycled coarse aggregate. the surface texture of the coarse recycled aggregate was more porous and rough when compared to natural aggregate. the density and specific gravity were lower and the water absorbability was higher in case of recycled aggregate due to low density and high absorption capacity of old mortar adhered to those. however, the rough surface of aggregate had beneficial effect on mechanical characteristics of concrete due to modification of fracture process. the method used for recycled aggregate production, preparing of aggregate in wet conditions and proper way of recycled aggregate concrete curing lead to gaining the strength properties of concrete required for structural applications. the results showed that the medium strength structural concrete can be produced using 100 % recycled aggregate. rac and frac showed similar trends in compressive as well as flexural strength development during 28 days of curing. the addition of steel fibre (0.52 % by volume) increased the flexural strength of recycled aggregate concrete and had a beneficial effect on fracture process and flexural behaviour of model beams. no significant changes was observed in the compressive strength. the concrete members with fibres were characterized by greater resistance to deflection 65 and strains in comparison to members of plain concrete. the fibre addition was particularly useful to control the post-crack regime of the load-strain curve of the recycled aggregate concrete. the load bearing capacity of recycled aggregate concrete beams was related to reinforcement ratio, but the increase in the capacity was greater for concrete with steel fibers. the test results reported in the paper are important and useful to understand the flexural behavior of recycled concrete beams. the research programme will be continued using different sizes of rc members and various load conditions, including long-term behavior of structural concrete as well as cyclic loading. the analysis of experimental results is essential in order to check the applicability of current design provision for recycled concrete beams. recycled aggregate is suitable for a wide range of concrete applications. however, its special properties have to be taken into consideration by the design of structures, concrete production, casting and curing in order to optimize performance. recycled aggregate should be considered more extensively in standards in order to exploit its potential. this is an important prerequisite toward a sustainable material flow. references ajdukiewicz, a., kliszczewicz, a. 2002. influence of recycled aggregates on mechanical properties of hs/hpc. cement & concrete composites, 24, 269–279. http://dx.doi.org/10.1016/s0958-9465(01)00012-9 andriuš, g., augonis, a., augonis, m., klepša, š., zingaila, t. 2013. flexural reinforced concrete elements residual stresses of fibres with limited reinforcement bond. journal of sustainable architecture and civil engineering, 2(3), 33–39. balendran, r. v ., zhou, f. p., nadeem, a., leung, a. y. t. 2002. influence of steel fibers on strength and ductility of normal and lightweight high strength concrete. building and environment, 37, 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34, 1975–1980. http://dx.doi.org/10.1016/j.cemconres.2004.02.009 lovato, p. s., possan, e., dal molin, d.c.c., masuero, a. b., ribeiro, j. l.d. 2012. modeling of mechanical properties and durability of recycled aggregate concretes. construction and building materials, 26, 437–447. http://dx.doi.org/10.1016/j.conbuildmat.2011.06.043 marie, i., quiasrawi, h. 2012. closed-loop recycling of recycled concrete aggregates. journal of cleaner production, 37, 243– 248. http://dx.doi.org/10.1016/j.jclepro.2012.07.020 marinković, s., radonjanin, v., malešev, m., ignjatović, i. 2010. comparative environmental assessment of natural and recycled aggregate concrete. waste management, 30, 2255– 2264. http://dx.doi.org/10.1016/j.wasman.2010.04.012 richardson, a., coventry, k., bacon, j. 2011. freeze/thaw durability of concrete with recycled demolition aggregate compared to virgin aggregate concrete. journal of cleaner production, 19, 272–277. http://dx.doi.org/10.1016/j.jclepro.2010.09.014 tabsh, s. w., abdelfatah, a.s. 2009. influence of recycled concrete aggregates on strength properties of concrete. construction and building materials, 23, 1163–1167. http://dx.doi.org/10.1016/j.conbuildmat.2008.06.007 van loo, w. 1998. closing the concrete loop – from reuse to recycling. in: dhir r.k, henderson n.a., limbachiya m.c. (eds). use of recycled concrete aggregate. london (uk): thomas telford publishing, 83–97. wang, w., kou, s., xing, f. 2013. deformation properties and direct shear of medium strength concrete prepared with 100 % recycled coarse aggregates. construction and building materials, 48, 187–193. http://dx.doi.org/10.1016/j.conbuildmat.2013.06.065 xiao, j., falkner, h. 2007. bond behavior between recycled aggregate concrete and steel rebars. construction and building materials, 21, 395–401. http://dx.doi.org/10.1016/j.conbuildmat.2005.08.008 received 2014 05 19 accepted after revision 2014 05 30 marta kosior-kazberuk – associate professor at bialystok university of technology, faculty of civil engineering, department of building structures. main research area: concrete and reinforced concrete structures, durability of building materials and structures, sustainable development in concrete technology. address: wiejska 45e, 15-351 bialystok, poland. tel.: +48 85 746 96 00 e-mail: m.kosior@pb.edu.pl mateusz grzywa – supervisor of technical department, fcum. main research area: concrete technology, sustainable development in civil engineering. address: okolnik 2, 00-368 warsaw, poland. tel.: +48 85 742 87 41 e-mail: grzywa@chopin.man.bialystok.pl 67 journal of sustainable architecture and civil engineering 2014/4/9 jsace 4/9 journal of sustainable architecture and civil engineering vol. 4 / no. 9 / 2014 pp. 67-73 doi 10.5755/j01.sace.9.4.7420 © kaunas university of technology received 2014/06/25 accepted after revision 2014/08/12 numerical investigations of the stressed-deformed state of buried pipelines nikolai shepelevich*, aleksei molchan republican unitary research enterprise for construction “institute belniis” (“institute belniis”, rue ) 15 “b”, f. skoriny str. 220114 minsk, belarus *corresponding author: shepelevich@belniis.by numerical investigations of the stressed-deformed state of buried pipelines made of reinforcedconcrete pipes http://dx.doi.org/10.5755/j01.sace.9.4.7420 introduction the method for determining the internal forces in longitudinal sections of the pipe wall based on the numerical analysis method has been proposed. the two-dimensional finite-element model simulating the annular section of the pipe and surrounding soil body are used. the external loads are presented as vertical pressures applied at the level of the pipe top +0.5 m. the calculation is performed by the iterative method with the account of the deformation parameters of the elements. the computation results conform well with the experimental data. keywords: reinforced-concrete pipes, numerical simulation, loads, bending moment, deformations. one of the main problems arising when computing and designing the reinforced-concrete pipes for buried pipelines consists in determining the internal forces (bending moments) occurring in longitudinal sections of the pipe walls under the action of external loads. here the maximum values of the bending moments depend not only on the external loads, but also on the geotechnical conditions of lying the pipes. the valid regulatory system of the cis countries contains only the technique provided in the construction norms and regulations (snip) 2.05.03-85(цитп госстроя ссср, 1985), according to which the loads and internal forces in the pipes to be laid in the road bodies. the main scope of application of reinforced-concrete pipes is construction of the water-supply and sewage pipelines, where the pipes are laid in trenches and their stressed-deformed state differs considerably from that of the pipes laid in the road body. in 1975, the project “instruction for determining the loads upon the buried pipelines” (сн00075) based on the use of semi-empirical dependencies obtained by g.k.klein (клейн г.к. 1968) was developed in the ussr. however, this instruction was neither approved nor published. the gost 6482-88 (издательство стандартов, 1989), where the drawings of pipes (including the reinforcement) and design conditions of their laying were provided, was valid in the ussr and journal of sustainable architecture and civil engineering 2014/4/9 68 russia till recently. this solved the problem of absence of a normative document for computing and designing the pipes, but constrained the development of their new engineering solutions and efficient manufacturing technologies. the investigation is aimed at the development of the technique of computing the reinforcedconcrete pipes laid in the soil based on the use of the computer-generated simulation. the geometrical dimensions of the reinforced-concrete pipes (diameter/length) are those that the pipes laid in the soil may be considered as annular elements being in the planar-deformation conditions. in the snip 2.5.03-85, the computational pattern presented in fig. 1 is used for determining the bending moments in longitudinal sections of the pipe wall. the bending moments м 1 , м 2 , м 3 , are determined from the formulae: methods where: d is the coefficient taking into account the section position, bed type and angle of contact of the pipe in the bed; r m and b are the average pipe radius and design section width, respectively; λ is the lateral soil pressure coefficient. (1) (2) м 1,2,3 = d · (p ν p n ) × r m 2 · b; or м 1,2,3 = d · p ν (1λ ) × r m 2 · b; as seen from (1)-(2), the value of the bending moments м 1 , м 2 , м 3 is affected considerably by the “passive” lateral soil pressure p n , which depends on the type of the soil and degree of its compaction. in the project сн00075, this factor was taken into consideration by applying the three degrees of compaction of the soil in the gaps between the pipes and the trench walls (in the pipeline project): the uncontrolled, increased and dense one (compaction by alluvion), to each of which a certain value of the lateral pressure coefficient for the given kind of soil λ corresponded. besides, the computational pattern (see fig.1) does not take into account the occurrence of the additional “reactive” lateral soil pressure when increasing the horizontal diameter (warping of the annular section of the pipe) during the formation of the cracks in the “dangerous” sections of the pipe wall. this problem can be solved using the method of computer-generated fig. 1 computational pattern and distribution diagram of the bending moments in longitudinal sections of the pipe wall 1. introduction one of the main problems arising when computing and designing the reinforced-concrete pipes for buried pipelines consists in determining the internal forces (bending moments) occurring in longitudinal sections of the pipe walls under the action of external loads. here the maximum values of the bending moments depend not only on the external loads, but also on the geotechnical conditions of lying the pipes. the valid regulatory system of the cis countries contains only the technique provided in the construction norms and regulations (snip) 2.05.03-85(цитп госстроя ссср, 1985), according to which the loads and internal forces in the pipes to be laid in the road bodies. the main scope of application of reinforced-concrete pipes is construction of the water-supply and sewage pipelines, where the pipes are laid in trenches and their stresseddeformed state differs considerably from that of the pipes laid in the road body. in 1975, the project “instruction for determining the loads upon the buried pipelines” (сн00075) based on the use of semi-empirical dependencies obtained by g.k.klein (клейн г.к. 1968) was developed in the ussr. however, this instruction was neither approved nor published. the gost 6482-88 (издательство стандартов, 1989), where the drawings of pipes (including the reinforcement) and design conditions of their laying were provided, was valid in the ussr and russia till recently. this solved the problem of absence of a normative document for computing and designing the pipes, but constrained the development of their new engineering solutions and efficient manufacturing technologies. the investigation is aimed at the development of the technique of computing the reinforced-concrete pipes laid in the soil based on the use of the computer-generated simulation. 2. methods the geometrical dimensions of the reinforcedconcrete pipes (diameter/length) are those that the pipes laid in the soil may be considered as annular elements being in the planar-deformation conditions. in the snip 2.5.03-85, the computational pattern presented in fig. 1 is used for determining the bending moments in longitudinal sections of the pipe wall. ν α ν fig.1. computational pattern and distribution diagram of the bending moments in longitudinal sections of the pipe wall where p v , p n and p v * are vertical and horizontal pressures, and bed reaction, respectively. the bending moments м 1 , м 2 , м 3 , are determined from the formulae: м 1,2,3 = δ⋅ (p v p n ) ⋅ r m 2 ⋅ b; or (1) м 1,2,3 = δ⋅ p v (1λ ) ⋅ r m 2 ⋅ b; (2) where δ is the coefficient taking into account the section position, bed type and angle of contact of the pipe in the bed; r m and b are the average pipe radius and design section width, respectively; numerical investigations of the stressed-deformed state of buried pipelines made of reinforced-concrete pipes the method for determining the internal forces in longitudinal sections of the pipe wall based on the numerical analysis method has been proposed. the two-dimensional finite-element model simulating the annular section of the pipe and surrounding soil body are used. the external loads are presented as vertical pressures applied at the level of the pipe top +0.5 m. the calculation is performed by the iterative method with the account of the deformation parameters of the elements. the computation results conform well with the experimental data. keywords: reinforced-concrete pipes, numerical simulation, loads, bending moment, deformations. nikolai shepelevich * , aleksei molchan republican unitary research enterprise for construction “institute belniis” (“institute belniis”, rue ), *e-mail: 1. introduction one of the main problems arising when computing and designing the reinforced-concrete pipes for buried pipelines consists in determining the internal forces (bending moments) occurring in longitudinal sections of the pipe walls under the action of external loads. here the maximum values of the bending moments depend not only on the external loads, but also on the geotechnical conditions of lying the pipes. the valid regulatory system of the cis countries contains only the technique provided in the construction norms and regulations (snip) 2.05.03-85(цитп госстроя ссср, 1985), according to which the loads and internal forces in the pipes to be laid in the road bodies. the main scope of application of reinforced-concrete pipes is construction of the water-supply and sewage pipelines, where the pipes are laid in trenches and their stresseddeformed state differs considerably from that of the pipes laid in the road body. in 1975, the project “instruction for determining the loads upon the buried pipelines” (сн00075) based on the use of semi-empirical dependencies obtained by g.k.klein (клейн г.к. 1968) was developed in the ussr. however, this instruction was neither approved nor published. the gost 6482-88 (издательство стандартов, 1989), where the drawings of pipes (including the reinforcement) and design conditions of their laying were provided, was valid in the ussr and russia till recently. this solved the problem of absence of a normative document for computing and designing the pipes, but constrained the development of their new engineering solutions and efficient manufacturing technologies. the investigation is aimed at the development of the technique of computing the reinforced-concrete pipes laid in the soil based on the use of the computer-generated simulation. 2. methods the geometrical dimensions of the reinforcedconcrete pipes (diameter/length) are those that the pipes laid in the soil may be considered as annular elements being in the planar-deformation conditions. in the snip 2.5.03-85, the computational pattern presented in fig. 1 is used for determining the bending moments in longitudinal sections of the pipe wall. ν α ν fig.1. computational pattern and distribution diagram of the bending moments in longitudinal sections of the pipe wall where p v , p n and p v * are vertical and horizontal pressures, and bed reaction, respectively. the bending moments м 1 , м 2 , м 3 , are determined from the formulae: м 1,2,3 = δ⋅ (p v p n ) ⋅ r m 2 ⋅ b; or (1) м 1,2,3 = δ⋅ p v (1λ ) ⋅ r m 2 ⋅ b; (2) where δ is the coefficient taking into account the section position, bed type and angle of contact of the pipe in the bed; r m and b are the average pipe radius and design section width, respectively; numerical investigations of the stressed-deformed state of buried pipelines made of reinforced-concrete pipes the method for determining the internal forces in longitudinal sections of the pipe wall based on the numerical analysis method has been proposed. the two-dimensional finite-element model simulating the annular section of the pipe and surrounding soil body are used. the external loads are presented as vertical pressures applied at the level of the pipe top +0.5 m. the calculation is performed by the iterative method with the account of the deformation parameters of the elements. the computation results conform well with the experimental data. keywords: reinforced-concrete pipes, numerical simulation, loads, bending moment, deformations. nikolai shepelevich * , aleksei molchan republican unitary research enterprise for construction “institute belniis” (“institute belniis”, rue ), *e-mail: p v , p n and p v * are vertical and horizontal pressures, and bed reaction, respectively fig. 2 computational finiteelement model of the pipe λ is the lateral soil pressure coefficient. as seen from (1)-(2), the value of the bending moments м 1 , м 2 , м 3 is affected considerably by the “passive” lateral soil pressure p n , which depends on the type of the soil and degree of its compaction. in the project сн00075, this factor was taken into consideration by applying the three degrees of compaction of the soil in the gaps between the pipes and the trench walls (in the pipeline project): the uncontrolled, increased and dense one (compaction by alluvion), to each of which a certain value of the lateral pressure coefficient for the given kind of soil λ corresponded. besides, the computational pattern (see fig.1) does not take into account the occurrence of the additional “reactive” lateral soil pressure when increasing the horizontal diameter (warping of the annular section of the pipe) during the formation of the cracks in the “dangerous” sections of the pipe wall. this problem can be solved using the method of computer-generated simulation. to solve this problem, the two-dimensional finite-element model (see fig. 2) is used. this model is formed as follows: the annular section of the pipe (of a single width) is formed by the rectilinear rod-shaped finite elements 1 conjugated rigidly with one another and arranged over the perimeter of the middle surface of the pipe; the length of the rod-shaped elements (l 0 ) is assumed to be 0.03…0.05 of the length of the circumference of the medial surface and their modulus of elasticity (е) according to the deformation curve for concrete of the specified strength class; the zone of contact between the pipe elements and the soil body is formed by the grid of rod-shaped contact elements 2 (with the compressive stiffness only); the soil for filling the gaps between the pipes and the trench walls is formed by flat rectangular and triangular (in the contact zones) soil elements 3 having its own weight; the modulus of deformation of the soil elements is adopted depending on the degree of compaction of the filling soil (coefficient k y ): 5 mpa for normal (uncontrolled) compaction degree; 15 mpa – for increased (up to 0.93 < k y < 0.95) compaction degree; 25 mpa – for high (up to k y > 0.95) compaction degree. the soil outside the trench (natural) is formed by the flat rectangular and triangular (in the zone of contact with the filling soil) soil elements 4, the modulus of deformation of which is to be assumed depending on the kind of the soil of the natural (undisturbed) structure surrounding the trench; the zone of contact of the filling soil with the soil of undisturbed structure is formed by special contact elements with finite shear modulus simulating the friction of the filling soil on the natural soil; the external load on the pipe (to be determined using the technique provided in the snip 2.05.03-85) is applied as uniform vertical pressures p v and p γ , applied at the level of the pipe top +0.5 m, where p v and p γ , are the total vertical pressure (including the variable load on the surface) and the pressure from the filling soil, respectively, computed on the basis of the existing techniques. the boundaries of the computational domain are assumed depending on the outer diameter of the pipe d e for the purpose of excluding the effect of the external loop on the computation results. h h 1 2 d e de b 2deb 2de 3 42 1 m 1,pl m 1,pl m 1,pl m 1,pl 5 5 6 7 pν pγ fig. 2. computational finite-element model of the pipe 1 – rod-shaped elements of the pipe wall; 2 – contact elements; 3 – flat elements of the filling soil; 4 – flat elements of the natural soil; 5 – zones of additional compaction of the filling soil; 6 – zone of additional compaction of the bed soil. for solving this problem, the computational software packages, such as “lyre”, “nastran”, etc. taking into account the physical and geometrical non-linearity can be used (городецкий а.с., евзеров и.д. 2009). when describing the finite elements, the following is assumed: modulus of deformation of the soil: e soil = 50 mpa – for simulating the soil of the undisturbed structure and e soil =5 mpa (15; 25 mpa) – for the filling soil; poisson ratio ν = 0.3; cohesion r c =22 kpa – for simulating the soil of the undisturbed structure and r c =1…5 kpa – for simulating the backfilling soil; soil density ρ = 17.7 kn/m 3 ; angle of internal friction φ = 30°; geometrical parameters b and h; diagrams of the material deformation. the computation is performed using the iterative method, by the step-by-step application of the external load (at least 10 stages). at each loading stage, the change in the stiffness of the rod-shaped finite elements of the pipe wall in the cracking zones as well as change in the deformation module of the filling soil in the additional compaction zones 5 and 6. this computation method makes it possible to determine the values of the internal forces of the bending moments in the rod-shaped elements simulating the pipe wall as well as the values of warping of the annular section of the pipe (changes in the vertical and horizontal diameter). 3. results figures 3-6 present the graphical dependencies of the bending moment values м max , in the walls of pipes ø1000 mm and 2000 mm and values of changes in the horizontal pipe diameter δ on the filling height н (to be used for computing the p v and p γ ). the modulus of deformation of the soil filling the gaps between the pipes and the trench walls е soil . is assumed to be 5; 15; 25 mpa (averaged values from project сн00075), to which various extent of its compaction (uncontrolled, increased and dense) corresponds). 1 – rod-shaped elements of the pipe wall; 2 – contact elements; 3 – flat elements of the filling soil; 4 – flat elements of the natural soil; 5 – zones of additional compaction of the filling soil; 6 – zone of additional compaction of the bed soil 69 journal of sustainable architecture and civil engineering 2014/4/9 simulation. to solve this problem, the two-dimensional finite-element model (see fig. 2) is used. this model is formed as follows: _ the annular section of the pipe (of a single width) is formed by the rectilinear rod-shaped finite elements 1 conjugated rigidly with one another and arranged over the perimeter of the middle surface of the pipe; _ the length of the rod-shaped elements (l 0 ) is assumed to be 0.03…0.05 of the length of the circumference of the medial surface and their modulus of elasticity (е) according to the deformation curve for concrete of the specified strength class; _ the zone of contact between the pipe elements and the soil body is formed by the grid of rod-shaped contact elements 2 (with the compressive stiffness only); _ the soil for filling the gaps between the pipes and the trench walls is formed by flat rectangular and triangular (in the contact zones) soil elements 3 having its own weight; _ the modulus of deformation of the soil elements is adopted depending on the degree of compaction of the filling soil (coefficient k y ): 5 mpa for normal (uncontrolled) compaction degree; 15 mpa – for increased (up to 0.93 < k y < 0.95) compaction degree; 25 mpa – for high (up to k y > 0.95) compaction degree. _ the soil outside the trench (natural) is formed by the flat rectangular and triangular (in the zone of contact with the filling soil) soil elements 4, the modulus of deformation of which is to be assumed depending on the kind of the soil of the natural (undisturbed) structure surrounding the trench; _ the zone of contact of the filling soil with the soil of undisturbed structure is formed by special contact elements with finite shear modulus simulating the friction of the filling soil on the natural soil; _ the external load on the pipe (to be determined using the technique provided in the snip 2.05.03-85) is applied as uniform vertical pressures p v and p γ , applied at the level of the pipe top +0.5 m, where p v and p γ , are the total vertical pressure (including the variable load on the surface) and the pressure from the filling soil, respectively, computed on the basis of the existing techniques. the boundaries of the computational domain are assumed depending on the outer diameter of the pipe d e for the purpose of excluding the effect of the external loop on the computation results. for solving this problem, the computational software packages, such as “lyre”, “nastran”, etc. taking into account the physical and geometrical non-linearity can be used (городецкий а.с., евзеров и.д. 2009). when describing the finite elements, the following is assumed: _ modulus of deformation of the soil: e soil = 50 mpa – for simulating the soil of the undisturbed structure and e soil =5 mpa (15; 25 mpa) – for the filling soil; _ poisson ratio ν = 0.3; _ cohesion r c =22 kpa – for simulating the soil of the undisturbed structure and r c =1…5 kpa – for simulating the backfilling soil; _ soil density ρ = 17.7 kn/m3; _ angle of internal friction φ = 30°; _ geometrical parameters b and h; _ diagrams of the material deformation. the computation is performed using the iterative method, by the step-by-step application of the external load (at least 10 stages). at each loading stage, the change in the stiffness of the rodjournal of sustainable architecture and civil engineering 2014/4/9 70 shaped finite elements of the pipe wall in the cracking zones as well as change in the deformation module of the filling soil in the additional compaction zones 5 and 6. this computation method makes it possible to determine the values of the internal forces of the bending moments in the rod-shaped elements simulating the pipe wall as well as the values of warping of the annular section of the pipe (changes in the vertical and horizontal diameter). figures 3-6 present the graphical dependencies of the bending moment values м max , in the walls of pipes ø1000 mm and 2000 mm and values of changes in the horizontal pipe diameter δ on the filling height н (to be used for computing the p v and p γ ). the modulus of deformation of the soil filling the gaps between the pipes and the trench walls е soil . is assumed to be 5; 15; 25 mpa (averaged values from project сн00075), to which various extent of its compaction (uncontrolled, increased and dense) corresponds). as seen from the graphs, the increase of the modulus of deformation of the soil filling the gaps between the pipes and the trench walls (for example, by using the sandy soil with steeping and layer-by-layer compaction) leads to the reduction of the maximum bending moments in the unsafe sections of the pipe wall by 20…35%, depending on the geometrical parameters of the pipes and depth of their burial. here the warping of the annular section of the pipe (δ) is reduced by 1.5...2. this phenomenon is conditioned by the action of the lateral soil pressure occurring as a reaction to warping of the annular section (δ). here no lateral pressure (p n ) (see the diagram in fig. 1) was applied explicitly to the pipe. it is obvious that the value of the reactive lateral soil pressure depends on the stiffness of the annular section of the pipe. in the reinforced-concrete pipes, the stiffness of the annular section decreases considerably in the process of formation and opening of the cracks. the cracks are formed in the longitudinal sections of the pipe results 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0 1 2 3 4 5 6 7 8 9 10 11 12 m , кнм h , м eгр=5 мпа eгр=15 мпа егр=25 мпа fig. 3. м max vs. н dependence for the 1000 mm diameter pipes 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 10 11 12 ∆, мм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 4. δ vs. н dependence for the 1000 mm diameter pipes 5 15 25 35 45 55 65 0 1 2 3 4 5 6 7 8 9 10 11 m , кнм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 5. м max vs. н dependence for the 2000 mm diameter pipes 0 2 4 6 8 10 12 14 16 0 1 2 3 4 5 6 7 8 9 10 11 ∆, мм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 6. δ vs. н dependence for the 2000 mm diameter pipes as seen from the graphs, the increase of the modulus of deformation of the soil filling the gaps between the pipes and the trench walls (for example, by using the sandy soil with steeping and layer-by-layer compaction) leads to the reduction of the maximum bending moments in the unsafe sections of the pipe wall by 20…35%, depending on the geometrical parameters of the pipes and depth of their burial. here the warping of the annular section of the pipe (δ) is reduced by 1.5...2. this phenomenon is conditioned by the action of the lateral soil pressure occurring as a reaction to warping of the annular section (δ). here no lateral pressure (p n ) (see the diagram in fig. 1) was applied explicitly to the pipe. it is obvious that the value of the reactive lateral soil pressure depends on the stiffness of the annular section of the pipe. in the reinforced-concrete pipes, the stiffness of the annular section decreases considerably in the process of formation and opening of the cracks. the cracks are formed in the longitudinal sections of the pipe wall in the zones of action of the maximum bending moments (see the distribution diagram м in fig. 1). to reveal the influence of this factor on the stressed-deformed state of the pipes, their computation without accounting this phenomena was performed. tables 1-2 presents the comparative values of the maximum bending moment м max and warping of the annular section δ for the 1000 and 2000 mm diameter pipes with the modulus of deformation of the filling soil e soil =15 mpa obtained from the linear-elastic and iterative computations. table 1. the comparative values of the maximum bending moment м max and warping of the annular section δ h, m м max , knm/m δ, mm iterative linearelastic iterative linearelastic 2 4.39 4.54 0.33 0.27 3 5.46 5.74 0.44 0.34 4 6.74 7.22 0.6 0.42 5 7.81 8.52 0.78 0.5 6 8.97 9.86 1.03 0.57 7 10.1 11.2 1.33 0.65 8 11.1 12.6 1.66 0.73 9 12.1 14.2 2.27 0.83 10 12.6 15.7 3.07 0.91 e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa h, m h, m h, m h, m mm mm knm knm 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0 1 2 3 4 5 6 7 8 9 10 11 12 m , кнм h , м eгр=5 мпа eгр=15 мпа егр=25 мпа fig. 3. м max vs. н dependence for the 1000 mm diameter pipes 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 10 11 12 ∆, мм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 4. δ vs. н dependence for the 1000 mm diameter pipes 5 15 25 35 45 55 65 0 1 2 3 4 5 6 7 8 9 10 11 m , кнм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 5. м max vs. н dependence for the 2000 mm diameter pipes 0 2 4 6 8 10 12 14 16 0 1 2 3 4 5 6 7 8 9 10 11 ∆, мм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 6. δ vs. н dependence for the 2000 mm diameter pipes as seen from the graphs, the increase of the modulus of deformation of the soil filling the gaps between the pipes and the trench walls (for example, by using the sandy soil with steeping and layer-by-layer compaction) leads to the reduction of the maximum bending moments in the unsafe sections of the pipe wall by 20…35%, depending on the geometrical parameters of the pipes and depth of their burial. here the warping of the annular section of the pipe (δ) is reduced by 1.5...2. this phenomenon is conditioned by the action of the lateral soil pressure occurring as a reaction to warping of the annular section (δ). here no lateral pressure (p n ) (see the diagram in fig. 1) was applied explicitly to the pipe. it is obvious that the value of the reactive lateral soil pressure depends on the stiffness of the annular section of the pipe. in the reinforced-concrete pipes, the stiffness of the annular section decreases considerably in the process of formation and opening of the cracks. the cracks are formed in the longitudinal sections of the pipe wall in the zones of action of the maximum bending moments (see the distribution diagram м in fig. 1). to reveal the influence of this factor on the stressed-deformed state of the pipes, their computation without accounting this phenomena was performed. tables 1-2 presents the comparative values of the maximum bending moment м max and warping of the annular section δ for the 1000 and 2000 mm diameter pipes with the modulus of deformation of the filling soil e soil =15 mpa obtained from the linear-elastic and iterative computations. table 1. the comparative values of the maximum bending moment м max and warping of the annular section δ h, m м max , knm/m δ, mm iterative linearelastic iterative linearelastic 2 4.39 4.54 0.33 0.27 3 5.46 5.74 0.44 0.34 4 6.74 7.22 0.6 0.42 5 7.81 8.52 0.78 0.5 6 8.97 9.86 1.03 0.57 7 10.1 11.2 1.33 0.65 8 11.1 12.6 1.66 0.73 9 12.1 14.2 2.27 0.83 10 12.6 15.7 3.07 0.91 e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa h, m h, m h, m h, m mm mm knm knm 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0 1 2 3 4 5 6 7 8 9 10 11 12 m , кнм h , м eгр=5 мпа eгр=15 мпа егр=25 мпа fig. 3. м max vs. н dependence for the 1000 mm diameter pipes 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 10 11 12 ∆, мм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 4. δ vs. н dependence for the 1000 mm diameter pipes 5 15 25 35 45 55 65 0 1 2 3 4 5 6 7 8 9 10 11 m , кнм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 5. м max vs. н dependence for the 2000 mm diameter pipes 0 2 4 6 8 10 12 14 16 0 1 2 3 4 5 6 7 8 9 10 11 ∆, мм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 6. δ vs. н dependence for the 2000 mm diameter pipes as seen from the graphs, the increase of the modulus of deformation of the soil filling the gaps between the pipes and the trench walls (for example, by using the sandy soil with steeping and layer-by-layer compaction) leads to the reduction of the maximum bending moments in the unsafe sections of the pipe wall by 20…35%, depending on the geometrical parameters of the pipes and depth of their burial. here the warping of the annular section of the pipe (δ) is reduced by 1.5...2. this phenomenon is conditioned by the action of the lateral soil pressure occurring as a reaction to warping of the annular section (δ). here no lateral pressure (p n ) (see the diagram in fig. 1) was applied explicitly to the pipe. it is obvious that the value of the reactive lateral soil pressure depends on the stiffness of the annular section of the pipe. in the reinforced-concrete pipes, the stiffness of the annular section decreases considerably in the process of formation and opening of the cracks. the cracks are formed in the longitudinal sections of the pipe wall in the zones of action of the maximum bending moments (see the distribution diagram м in fig. 1). to reveal the influence of this factor on the stressed-deformed state of the pipes, their computation without accounting this phenomena was performed. tables 1-2 presents the comparative values of the maximum bending moment м max and warping of the annular section δ for the 1000 and 2000 mm diameter pipes with the modulus of deformation of the filling soil e soil =15 mpa obtained from the linear-elastic and iterative computations. table 1. the comparative values of the maximum bending moment м max and warping of the annular section δ h, m м max , knm/m δ, mm iterative linearelastic iterative linearelastic 2 4.39 4.54 0.33 0.27 3 5.46 5.74 0.44 0.34 4 6.74 7.22 0.6 0.42 5 7.81 8.52 0.78 0.5 6 8.97 9.86 1.03 0.57 7 10.1 11.2 1.33 0.65 8 11.1 12.6 1.66 0.73 9 12.1 14.2 2.27 0.83 10 12.6 15.7 3.07 0.91 e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa h, m h, m h, m h, m mm mm knm knm fig. 3 м max νs. н dependence for the 1000 mm diameter pipes fig. 4 δ νs. н dependence for the 1000 mm diameter pipes fig. 5 м max νs. н dependence for the 2000 mm diameter pipes 71 journal of sustainable architecture and civil engineering 2014/4/9 wall in the zones of action of the maximum bending moments (see the distribution diagram м in fig. 1). to reveal the influence of this factor on the stressed-deformed state of the pipes, their computation without accounting this phenomena was performed. tables 1-2 presents the comparative values of the maximum bending moment м max and warping of the annular section δ for the 1000 and 2000 mm diameter pipes with the modulus of deformation of the filling soil e soil =15 mpa obtained from the linear-elastic and iterative computations. as the load grows (the filling height н increases), the results of computation of the pipes using the linear-elastic and iterative model become considerably different so that the heavier is the load, the greater are the differences between the results. this phenomenon is conditioned by the fact that as the cracks occur in the “unsafe” sections of the pipe wall (bottom line, soffit and at the horizontal diameter level), the warping of the annular section grows. the additional (reactive) lateral back pressure of the soil filling the gaps between the pipes and the trench walls that just causes the reduction of the bending moments м max. . the most significant occurrence of this phenomenon takes place in the large-diameter pipes having lesser annular stiffness. so in the pipe with the diameter of 2000 mm at the filling height н=10 m, the computed value of м max was reduced by 34% in comparison with the elastic computation. to check the adequacy of the proposed computational model, the comparison of the computed values of warping of the annular section d of the pipes with the diameter of 2000 mm with the results of their measurements was performed. these pipes were used in h, m м max , knm/m δ, mm iterative linearelastic iterative linearelastic 2 4.39 4.54 0.33 0.27 3 5.46 5.74 0.44 0.34 4 6.74 7.22 0.6 0.42 5 7.81 8.52 0.78 0.5 6 8.97 9.86 1.03 0.57 7 10.1 11.2 1.33 0.65 8 11.1 12.6 1.66 0.73 9 12.1 14.2 2.27 0.83 10 12.6 15.7 3.07 0.91 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 0 1 2 3 4 5 6 7 8 9 10 11 12 m , кнм h , м eгр=5 мпа eгр=15 мпа егр=25 мпа fig. 3. м max vs. н dependence for the 1000 mm diameter pipes 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 10 11 12 ∆, мм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 4. δ vs. н dependence for the 1000 mm diameter pipes 5 15 25 35 45 55 65 0 1 2 3 4 5 6 7 8 9 10 11 m , кнм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 5. м max vs. н dependence for the 2000 mm diameter pipes 0 2 4 6 8 10 12 14 16 0 1 2 3 4 5 6 7 8 9 10 11 ∆, мм h , м eгр=5 мпа eгр=15 мпа eгр=25 мпа fig. 6. δ vs. н dependence for the 2000 mm diameter pipes as seen from the graphs, the increase of the modulus of deformation of the soil filling the gaps between the pipes and the trench walls (for example, by using the sandy soil with steeping and layer-by-layer compaction) leads to the reduction of the maximum bending moments in the unsafe sections of the pipe wall by 20…35%, depending on the geometrical parameters of the pipes and depth of their burial. here the warping of the annular section of the pipe (δ) is reduced by 1.5...2. this phenomenon is conditioned by the action of the lateral soil pressure occurring as a reaction to warping of the annular section (δ). here no lateral pressure (p n ) (see the diagram in fig. 1) was applied explicitly to the pipe. it is obvious that the value of the reactive lateral soil pressure depends on the stiffness of the annular section of the pipe. in the reinforced-concrete pipes, the stiffness of the annular section decreases considerably in the process of formation and opening of the cracks. the cracks are formed in the longitudinal sections of the pipe wall in the zones of action of the maximum bending moments (see the distribution diagram м in fig. 1). to reveal the influence of this factor on the stressed-deformed state of the pipes, their computation without accounting this phenomena was performed. tables 1-2 presents the comparative values of the maximum bending moment м max and warping of the annular section δ for the 1000 and 2000 mm diameter pipes with the modulus of deformation of the filling soil e soil =15 mpa obtained from the linear-elastic and iterative computations. table 1. the comparative values of the maximum bending moment м max and warping of the annular section δ h, m м max , knm/m δ, mm iterative linearelastic iterative linearelastic 2 4.39 4.54 0.33 0.27 3 5.46 5.74 0.44 0.34 4 6.74 7.22 0.6 0.42 5 7.81 8.52 0.78 0.5 6 8.97 9.86 1.03 0.57 7 10.1 11.2 1.33 0.65 8 11.1 12.6 1.66 0.73 9 12.1 14.2 2.27 0.83 10 12.6 15.7 3.07 0.91 e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa e soil =5 mpa e soil =15 mpa e soil =25 mpa h, m h, m h, m h, m mm mm knm knm fig. 6 δ νs. н dependence for the 2000 mm diameter pipes table 1 the comparative values of the maximum bending moment м max and warping of the annular section δ table 2 the comparative values of the maximum bending moment м max and warping of the annular section δ h, m м max , knm/m δ, mm iterative linearelastic iterative linearelastic 2 13.69 16.0 1.90 1.30 3 17.70 20.7 2.66 1.83 4 21.38 25.8 3.54 2.20 5 25.07 31.1 4.49 2.60 6 28.62 36.5 5.56 3.10 7 31.82 42.0 6.72 3.53 8 34.68 47.5 8.07 3.92 9 36.54 53.8 9.89 4.50 10 38.24 58.6 11.81 4.90 journal of sustainable architecture and civil engineering 2014/4/9 72 construction of storm drains in the city of minsk, their depth was from 2 to 7.5 m. basic parameters of the pipes: _ inner diameter – 2000 mm; _ useful length (without the hub) 2,5 m; _ type of pipe connection joint – hub with rubber sealing; _ pipe wall thickness 150 mm; _ pipe wall is reinforced with double cylindrical hulls symmetrically placed at inner and outer faces; _ design concrete class – с25/30. design solution of pipe is shown in fig. 7. designers of these pipes (including authors of this article) were monitoring the technical condition of the pipes both immediately after filling as well as during the operation process. degree of the pipe loading was determined by measuring changes of its horizontal diameter, and by presence of cracks in the crown and their opening width. fig. 8 presents the graphical dependencies (obtained by processing the results of pipe measurements after backfilling) of changes of the table 2. the comparative values of the maximum bending moment м max and warping of the annular section δ h, m м max , knm/m δ, mm iterative linearelastic iterative linearelastic 2 13.69 16.0 1.90 1.30 3 17.70 20.7 2.66 1.83 4 21.38 25.8 3.54 2.20 5 25.07 31.1 4.49 2.60 6 28.62 36.5 5.56 3.10 7 31.82 42.0 6.72 3.53 8 34.68 47.5 8.07 3.92 9 36.54 53.8 9.89 4.50 10 38.24 58.6 11.81 4.90 as the load grows (the filling height н increases), the results of computation of the pipes using the linear-elastic and iterative model become considerably different so that the heavier is the load, the greater are the differences between the results. this phenomenon is conditioned by the fact that as the cracks occur in the “unsafe” sections of the pipe wall (bottom line, soffit and at the horizontal diameter level), the warping of the annular section grows. the additional (reactive) lateral back pressure of the soil filling the gaps between the pipes and the trench walls that just causes the reduction of the bending moments м max. . the most significant occurrence of this phenomenon takes place in the large-diameter pipes having lesser annular stiffness. so in the pipe with the diameter of 2000 mm at the filling height н=10 m, the computed value of м max was reduced by 34% in comparison with the elastic computation. to check the adequacy of the proposed computational model, the comparison of the computed values of warping of the annular section δ of the pipes with the diameter of 2000 mm with the results of their measurements was performed. these pipes were used in construction of storm drains in the city of minsk, their depth was from 2 to 7.5 m. basic parameters of the pipes: inner diameter – 2000 mm; useful length (without the hub) 2,5 m; type of pipe connection joint – hub with rubber sealing; pipe wall thickness 150 mm; pipe wall is reinforced with double cylindrical hulls symmetrically placed at inner and outer faces; design concrete class – с25/30. design solution of pipe is shown in fig. 7. fig. 7. design solution of pipe. 1 – external cylindrical hull; 2 – internal cylindrical hull designers of these pipes (including authors of this article) were monitoring the technical condition of the pipes both immediately after filling as well as during the operation process. degree of the pipe loading was determined by measuring changes of its horizontal diameter, and by presence of cracks in the crown and their opening width. fig. 8 presents the graphical dependencies (obtained by processing the results of pipe measurements after backfilling) of changes of the horizontal diameter δ and maximum crack opening width wk at various filling heights (н) of the pipes. ordinate axis also presents computed vertical (equivalent) linear load р according to project сн00075 (for pipes laid in sandy soils on a natural profiled bed with angle of contact 2α=90° and with high degree of compaction of the soil filling the gaps between the pipes and the trench walls). fig. 8. graphs: 1 – н vs. δ; 2 – н vs w k as seen from graph 1 (see fig. 8), the values of warping of the annular sections of the pipes δ conform well with the data of table 2 (in the iterative computation with the account of cracking). here the computed values м max as per table 2 (for iterative computation) conform also well with the respective values computed from the equivalent linear load р according to project сн00075 for high degree of compaction (alluvion) of the soil filling the gaps between the pipes and the trench walls. mm mm p, kn/m h, m mm horizontal diameter d and maximum crack opening width wk at various filling heights (н) of the pipes. ordinate axis also presents computed vertical (equivalent) linear load р according to project сн00075 (for pipes laid in sandy soils on a natural profiled bed with angle of contact 2α=90° and with high degree of compaction of the soil filling the gaps between the pipes and the trench walls). as seen from graph 1 (see fig. 8), the values of warping of the annular sections of the pipes d conform well with the data of table 2 (in the iterative computation with the account of cracking). here the computed values м max as per table 2 (for iterative computation) conform also well with the respective values computed from the equivalent linear load р according to project сн00075 for high degree of compaction (alluvion) of the soil filling the gaps between the pipes and the trench walls. fig. 8 graphs: 1 – н vs.d; 2 – н vs wkcylindrical hull table 2. the comparative values of the maximum bending moment м max and warping of the annular section δ h, m м max , knm/m δ, mm iterative linearelastic iterative linearelastic 2 13.69 16.0 1.90 1.30 3 17.70 20.7 2.66 1.83 4 21.38 25.8 3.54 2.20 5 25.07 31.1 4.49 2.60 6 28.62 36.5 5.56 3.10 7 31.82 42.0 6.72 3.53 8 34.68 47.5 8.07 3.92 9 36.54 53.8 9.89 4.50 10 38.24 58.6 11.81 4.90 as the load grows (the filling height н increases), the results of computation of the pipes using the linear-elastic and iterative model become considerably different so that the heavier is the load, the greater are the differences between the results. this phenomenon is conditioned by the fact that as the cracks occur in the “unsafe” sections of the pipe wall (bottom line, soffit and at the horizontal diameter level), the warping of the annular section grows. the additional (reactive) lateral back pressure of the soil filling the gaps between the pipes and the trench walls that just causes the reduction of the bending moments м max. . the most significant occurrence of this phenomenon takes place in the large-diameter pipes having lesser annular stiffness. so in the pipe with the diameter of 2000 mm at the filling height н=10 m, the computed value of м max was reduced by 34% in comparison with the elastic computation. to check the adequacy of the proposed computational model, the comparison of the computed values of warping of the annular section δ of the pipes with the diameter of 2000 mm with the results of their measurements was performed. these pipes were used in construction of storm drains in the city of minsk, their depth was from 2 to 7.5 m. basic parameters of the pipes: inner diameter – 2000 mm; useful length (without the hub) 2,5 m; type of pipe connection joint – hub with rubber sealing; pipe wall thickness 150 mm; pipe wall is reinforced with double cylindrical hulls symmetrically placed at inner and outer faces; design concrete class – с25/30. design solution of pipe is shown in fig. 7. fig. 7. design solution of pipe. 1 – external cylindrical hull; 2 – internal cylindrical hull designers of these pipes (including authors of this article) were monitoring the technical condition of the pipes both immediately after filling as well as during the operation process. degree of the pipe loading was determined by measuring changes of its horizontal diameter, and by presence of cracks in the crown and their opening width. fig. 8 presents the graphical dependencies (obtained by processing the results of pipe measurements after backfilling) of changes of the horizontal diameter δ and maximum crack opening width wk at various filling heights (н) of the pipes. ordinate axis also presents computed vertical (equivalent) linear load р according to project сн00075 (for pipes laid in sandy soils on a natural profiled bed with angle of contact 2α=90° and with high degree of compaction of the soil filling the gaps between the pipes and the trench walls). fig. 8. graphs: 1 – н vs. δ; 2 – н vs w k as seen from graph 1 (see fig. 8), the values of warping of the annular sections of the pipes δ conform well with the data of table 2 (in the iterative computation with the account of cracking). here the computed values м max as per table 2 (for iterative computation) conform also well with the respective values computed from the equivalent linear load р according to project сн00075 for high degree of compaction (alluvion) of the soil filling the gaps between the pipes and the trench walls. mm mm p, kn/m h, m mm fig. 7 design solution of pipe 1 – external cylindrical hull; 2 – internal cylindrical hull thus, the technique for computing the buried pipelines made of reinforced-concrete pipes by the numerical simulation method using the finite-element model conforms well with the similar results of the computation according to project сн 00075 and corresponds to the experimental data. the advantage of the technique being proposed consists in the possibility of simulation of various geotechnical conditions of lying the pipes (in an embankment, trench, slit, etc.) as well as degree of compaction of the surrounding soil. in so doing, the computations take into account the change in the stiffness of the annular section of the pipe in the process of formation and opening of cracks. the proposed technique can be recommended for computing and designing the buried pipelines made of reinforced-concrete pipes. conclusions 73 journal of sustainable architecture and civil engineering 2014/4/9 shepelevich n.i., molchan a.e. 2010. experimental investigation of bearing capacity of reinforced concrete non-pressure 2000 and 2400 mm diameter pipes for deep burial. in advanced construction proceedings of the 2nd international conference. kaunas 2010. 107-112. городецкий а.с. евзеров и.д. 2009. компьютерные модели конструкций [computational model of structures]. москва. издательство асв, 36-39. references гост 6482-88 трубы железобетонные безнапорные. технические условия [reinforced concrete non-pressure pipes. specifications]. – м.: издательство стандартов, 1989. клейн г.к. 1968. расчет подземных трубопроводов [computation of the buried pipelines]. м., стройиздат, 98 с. мосты и трубы: снип 2.05.03-85. – м.: цитп госстроя ссср, 1985. nikolai shepelevich header of laboratory scientific research laboratory, republican unitary research enterprise for construction “institute belniis” (“institute belniis”, rue), belarus main research area computing and designing the reinforced-concrete structures for buried engineering constructions address 15 “b”, f. skoriny str. 220114 minsk, belarus tel. (017) 267-92-26; (029) 679-89-18 e-mail: shepelevich@belniis.by aleksei molchan principal engineer scientific research laboratory, republican unitary research enterprise for construction “institute belniis” (“institute belniis”, rue), belarus main research area computing and designing the reinforced-concrete structures for buried engineering constructions address 15 “b”, f. skoriny str. 220114 minsk, belarus tel. (017) 263-61-22 e-mail: m.a.e.81@mail.ru about the authors 41 journal of sustainable architecture and civil engineering 2015/2/11 jsace 2/11 journal of sustainable architecture and civil engineering vol. 2 / no. 11 / 2015 pp. 41-51 doi 10.5755/j01.sace.11.2.9986 © kaunas university of technology comparison of calculation methods of renewable energy generated by electric heat pumps received 2015/01/25 accepted after revision 2015/04/06 comparison of calculation methods of renewable energy generated by electric heat pumps *corresponding author: rokas.tamasauskas@ktu.edu http://dx.doi.org/10.5755/j01.sace.11.2.9986 rokas tamašauskas*, edmundas monstvilas, raimondas bliūdžius, karolis banionis, kęstutis miškinis institute of architecture and construction, kaunas university of technology tunelio g. 60, lt-44405 kaunas, lithuania heat pumps are widely used in buildings due to high energy performance and environmental-friendliness. 2010/31/eu directive of the european parliament and council requires assessing the consumption of primary energy generated from renewable sources when calculating the energy performance of buildings. however, the equation given in the 2009/28/eu directive and guidelines 2013/114/eu of the european commission does not take into account the amount of energy supplied by electric heat pumps into buildings. the paper presents the method that does not assess the energy input of primary sources for transforming electric power and for this reason, the calculations result in a lesser amount of energy than the ones obtained by the method of 2013/114/eu directive. the calculation results proved that using merely heat pumps in nearly zero-energy buildings will not ensure the necessary amount of energy from renewable primary energy sources. hence, to ensure the lacking amount of energy other renewable energy sources, such as solar panels, wind power plants, hydro power plants, biofuel, etc. are necessary to use. keywords: heat pumps, primary energy, renewable energy, non-renewable energy, energy performance of buildings. a heat pump is equipment that transforms aerothermal, geothermal or hydrothermal energy into higher-temperature heat that is used to heat buildings and/or water. high efficiency of heat pumps and the requirements of energy performance of buildings becoming more demanding are the reasons why researchers’ interest in heat pumps as one of the most promising heating sources increases accordingly. however, the method of calculating the amount of heat supplied to the building by heat pumps fed on renewable and non-renewable sources is not widely discussed in literature sources. for example, mendes compares absorption heat pumps fed on solar energy to pressure heat pumps in respect of primary energy use (mendes et al. 1998). gea analyses an up-to-date air heat pump system combining dryer wheel technology and radial cooling/heating. they assess the need for primary energy in the processes of cooling introduction journal of sustainable architecture and civil engineering 2015/2/11 42 and drying, as well as cooling, drying and heating by comparing the potential of such hybrid systems in saving primary energy with a traditional air heat pump system (gea et al. 2011). balta assess the exergetic energy released in the building from a primary energy source, which is the method applied in the premises heated by a geothermal heat pump (balta et al. 2008). moreover, huchtemann compares highly efficient condensing boilers to heat pumps, assess the efficiency of various types of fuel used, and the factors of primary energy and co 2 emission conversion (huchtemann et al. 2012). similarly, by comparing two systems for heating water, namely a heat pump combined with water heating solar panels, and a gas boiler, tagliafico estimates the possibility to save primary energy. the research has been performed on pools, but most of the criteria and results of the analysis are valid for buildings in need of hot water as well (tagliafico et al. 2012). further, tagliafico also examines a heat pump combined with solar panels and used for heating a variety of water types (tagliafico et al. 2014). zhaon analyses heating and cooling systems including a heat pump with a gas-driven engine, and propose using residual heat from the engine to reach higher primary energy coefficients (zhaon et al. 2011). lee compares two types of heat pumps (fed on electricity and gas) (lee et al. 2012). teng assess the influence of gas turbine capacity of an absorption heat pump and the strategy of its use on the consumption of primary energy in a building (teng et al. 2014). a new method of assessment is presented by zhang who analyses the seasonal primary energy indicator of a gas-driven heat pump of a water heater (zhang et al. 2014). elgendy analyses the characteristics of a gas-driven heat pump with an integrated heat recovery/regeneration subsystem, focusing on the temperature of outflowing water, heating capacity and primary energy coefficients (elgendy et al. 2014). in regard to the primary energy efficiency criterion, wu compare an electric soil heat pump with absorption soil heat pump, and estimate the influence of thermal imbalance of soil on energy efficiency indicators. in their further research (wu et al. 2013), wu analyses a combined heating/cooling/hot water preparation system with a geothermal absorption heat pump used in cold climate zones. during the simulation, the imbalance of soil has been diminished and a part of recovered condensation/absorption heat used to produce hot water by a heat pump. thus, such a combined system improves the efficiency of primary energy consumption (wu et al. 2014). the possibility of using heat compensation equipment with a thermo siphon in case of heating buildings by soil heat pumps in cold climate zones is discussed by you who claims that longterm exploitation of a heat pump reduces its efficiency due to soil cooling down (you et. al. 2014). havelsky uses primary energy indicators to analyse cogeneration system connected to heat pumps (havelsky 1999). hebenstreit looks at the operating input, primary energy consumption efficiency, and greenhouse gas emission to study the possibility of using a heat pump in an active condensation system by regenerating heat from biomass-driven boilers (hebenstreit et. al. 2014). yang considers potential and efficiency of a heat pump in ventilating and heating a greenhouse by the use of redundant thermal air energy formed therein (yang et al. 2013). a hybrid heating system composed of a sewage thermal energy-driven heat pump and a gas boiler is analyzed by li who examine its optimal operation strategy in order to reduce annual energy need (li et al. 2013). bayera assess the pumps in respect of the reduction of co 2 emission (bayera et al. 2012). they presuppose that electric power generation, becoming more ecological in the future, will lead to the increased efficiency of the pumps. having compared various types of heat pumps and their operational principles, sarbu states that better heat pump efficiency indicators are reached by combining heating and cooling as well as increasing the amount of renewable energy in the total of electric power used (sarbu et al. 2014). the comparison of a heat pump to a gas boiler is presented by cabrol taking into account co 2 emission (cabrol et al. 2012). they claim that increasing the mass of the building or installing additional heat insulation enables reaching an acceptable 43 journal of sustainable architecture and civil engineering 2015/2/11 thermal comfort level during the heating season even if the air heat pump is not operating at maximum capacity. rosiek estimates the amounts of primary energy consumption and co 2 emission by comparing different building cooling; heating and electric power generation systems based on the combination of renewable energy sources with traditional systems (rosiek et al. 2013). the presented work analyzed existing and developing systems and methodologies of consumed and generated energy by heat pumps. the objectives are to propose the methodology evaluating renewable energy generated by electric heat pump while considering factors such as the primary renewable and non-renewable energy, efficiency of heat pumps, the proportion of primary renewable energy in a building’s overall energy consumption. the efficiency of traditional heat sources (gas, solid fuel, electric boilers, etc.) is defined by the useful efficiency coefficient η h.eq , the value of which shows the ratio of the amount of thermal energy produced by a heat source to the amount of thermal energy present in the energy source (gas, solid fuel, electricity, etc.) used to produce heat. thus, the dimension of the coefficient stands as “the amount of thermal energy/ “the amount of thermal energy”. the efficiency of an electric heat pump is assessed by a seasonal performance factor η spf that defines the ratio of the amount of thermal energy produced by a heat pump to the amount of electricity used by the pump to produce that energy. η spf dimension can be expressed as “the amount of thermal energy”/ “the amount of electricity”. the η spf value of a heat pump is estimated by testing in accordance with the lst en 15450:2008 (2008) standard. if the value of useful efficiency of electricity generation η el is known (i.e. the ratio between the generated amount of electric power and the amount of energy in the energy sources used to produce that energy), the value of electric heat pump coefficient η h.eq can be estimated as follows: research problem definition (1) the efficiency of an electric heat pump is assessed by a seasonal performance factor ηspf that defines the ratio of the amount of thermal energy produced by a heat pump to the amount of electricity used by the pump to produce that energy. ηspf dimension can be expressed as “the amount of thermal energy”/ “the amount of electricity”. the ηspf value of a heat pump is estimated by testing in accordance with the lst en 15450:2008 (2008) standard. if the value of useful efficiency of electricity generation ηel is known (i.e. the ratio between the generated amount of electric power and the amount of energy in the energy sources used to produce that energy), the value of electric heat pump coefficient ηh.eq can be estimated as follows: elspfeqh  . (1) if (1ηh.eq)>0, the value of (1ηh.eq) indicates the amount of thermal energy present in the energy source (gas, solid fuel, etc.) that was not converted into thermal energy by that source. (1ηh.eq)<0 suggests that more thermal energy was produced while transforming the energy of a source into thermal energy than the amount of energy initially held by the energy source. in such a case, a part of energy is generated from renewable energy rather than the thermal energy initially present in the source. as follows, the value of (ηh.eq-1) defines the part of thermal energy that may be ascribed to the thermal energy generated from renewable sources and initially present in the traditional source (gas, solid fuel, etc.). the guidelines of the european commission 2013/114/eu, specifying the requirement of the eu directive 2009/28/eu to calculate the part of renewable energy generated using different technology-based heat pumps, provides a statistical method with the following equation: )11( spf usableeres ee   (2) here: eusable, the amount of energy suitable for use and supplied by heat pumps is estimated by equation (3): ratedhpusable phe  (3) here: hhp – the equivalent amount of hours of a heat pump operating at full load (h); prated – capacity of a heat pump of the respective type (kwh). to perform statistical calculations the hhp values have to be estimated in accordance with the data given in the guidelines 2013/114/eu of the european commission that are linked to the climate conditions of the respective eu member state. thus, depending on the climate conditions and the type of a heat pump, fixed hhp values unrelated to the energy needs of a building were determined in the corresponding climate zones. the 2010/31/eu directive requires estimating the energy performance of buildings in regard to the primary energy input, whereas equation (2), given in 2013/114/eu, enables estimating “the part of renewable energy generated by heat pumps” that is related neither to the requirements of the 2010/31/eu directive nor the lst en 15450:2008 standard. equation (3) cannot be applied for calculating primary energy since the physical meaning of its multiplier )11( spf  is as follows: amountenergythermal amountpowerelectricamountenergythermal amountpowerelectric amountenergythermalspf    1 1 1 1  (4) if (1η h.eq )>0, the value of (1η h . eq ) indicates the amount of thermal energy present in the energy source (gas, solid fuel, etc.) that was not converted into thermal energy by that source. (1η h . eq )<0 suggests that more thermal energy was produced while transforming the energy of a source into thermal energy than the amount of energy initially held by the energy source. in such a case, a part of energy is generated from renewable energy rather than the thermal energy initially present in the source. as follows, the value of (η h.eq-1 ) defines the part of thermal energy that may be ascribed to the thermal energy generated from renewable sources and initially present in the traditional source (gas, solid fuel, etc.). the guidelines of the european commission 2013/114/eu, specifying the requirement of the eu directive 2009/28/eu to calculate the part of renewable energy generated using different technology-based heat pumps, provides a statistical method with the following equation: here: e usable , the amount of energy suitable for use and supplied by heat pumps is estimated by equation (3):(2) the efficiency of an electric heat pump is assessed by a seasonal performance factor ηspf that defines the ratio of the amount of thermal energy produced by a heat pump to the amount of electricity used by the pump to produce that energy. ηspf dimension can be expressed as “the amount of thermal energy”/ “the amount of electricity”. the ηspf value of a heat pump is estimated by testing in accordance with the lst en 15450:2008 (2008) standard. if the value of useful efficiency of electricity generation ηel is known (i.e. the ratio between the generated amount of electric power and the amount of energy in the energy sources used to produce that energy), the value of electric heat pump coefficient ηh.eq can be estimated as follows: elspfeqh  . (1) if (1ηh.eq)>0, the value of (1ηh.eq) indicates the amount of thermal energy present in the energy source (gas, solid fuel, etc.) that was not converted into thermal energy by that source. (1ηh.eq)<0 suggests that more thermal energy was produced while transforming the energy of a source into thermal energy than the amount of energy initially held by the energy source. in such a case, a part of energy is generated from renewable energy rather than the thermal energy initially present in the source. as follows, the value of (ηh.eq-1) defines the part of thermal energy that may be ascribed to the thermal energy generated from renewable sources and initially present in the traditional source (gas, solid fuel, etc.). the guidelines of the european commission 2013/114/eu, specifying the requirement of the eu directive 2009/28/eu to calculate the part of renewable energy generated using different technology-based heat pumps, provides a statistical method with the following equation: )11( spf usableeres ee   (2) here: eusable, the amount of energy suitable for use and supplied by heat pumps is estimated by equation (3): ratedhpusable phe  (3) here: hhp – the equivalent amount of hours of a heat pump operating at full load (h); prated – capacity of a heat pump of the respective type (kwh). to perform statistical calculations the hhp values have to be estimated in accordance with the data given in the guidelines 2013/114/eu of the european commission that are linked to the climate conditions of the respective eu member state. thus, depending on the climate conditions and the type of a heat pump, fixed hhp values unrelated to the energy needs of a building were determined in the corresponding climate zones. the 2010/31/eu directive requires estimating the energy performance of buildings in regard to the primary energy input, whereas equation (2), given in 2013/114/eu, enables estimating “the part of renewable energy generated by heat pumps” that is related neither to the requirements of the 2010/31/eu directive nor the lst en 15450:2008 standard. equation (3) cannot be applied for calculating primary energy since the physical meaning of its multiplier )11( spf  is as follows: amountenergythermal amountpowerelectricamountenergythermal amountpowerelectric amountenergythermalspf    1 1 1 1  (4) here: h hp – the equivalent amount of hours of a heat pump operating at full load (h); p rated – capacity of a heat pump of the respective type (kwh). (3) the efficiency of an electric heat pump is assessed by a seasonal performance factor ηspf that defines the ratio of the amount of thermal energy produced by a heat pump to the amount of electricity used by the pump to produce that energy. ηspf dimension can be expressed as “the amount of thermal energy”/ “the amount of electricity”. the ηspf value of a heat pump is estimated by testing in accordance with the lst en 15450:2008 (2008) standard. if the value of useful efficiency of electricity generation ηel is known (i.e. the ratio between the generated amount of electric power and the amount of energy in the energy sources used to produce that energy), the value of electric heat pump coefficient ηh.eq can be estimated as follows: elspfeqh  . (1) if (1ηh.eq)>0, the value of (1ηh.eq) indicates the amount of thermal energy present in the energy source (gas, solid fuel, etc.) that was not converted into thermal energy by that source. (1ηh.eq)<0 suggests that more thermal energy was produced while transforming the energy of a source into thermal energy than the amount of energy initially held by the energy source. in such a case, a part of energy is generated from renewable energy rather than the thermal energy initially present in the source. as follows, the value of (ηh.eq-1) defines the part of thermal energy that may be ascribed to the thermal energy generated from renewable sources and initially present in the traditional source (gas, solid fuel, etc.). the guidelines of the european commission 2013/114/eu, specifying the requirement of the eu directive 2009/28/eu to calculate the part of renewable energy generated using different technology-based heat pumps, provides a statistical method with the following equation: )11( spf usableeres ee   (2) here: eusable, the amount of energy suitable for use and supplied by heat pumps is estimated by equation (3): ratedhpusable phe  (3) here: hhp – the equivalent amount of hours of a heat pump operating at full load (h); prated – capacity of a heat pump of the respective type (kwh). to perform statistical calculations the hhp values have to be estimated in accordance with the data given in the guidelines 2013/114/eu of the european commission that are linked to the climate conditions of the respective eu member state. thus, depending on the climate conditions and the type of a heat pump, fixed hhp values unrelated to the energy needs of a building were determined in the corresponding climate zones. the 2010/31/eu directive requires estimating the energy performance of buildings in regard to the primary energy input, whereas equation (2), given in 2013/114/eu, enables estimating “the part of renewable energy generated by heat pumps” that is related neither to the requirements of the 2010/31/eu directive nor the lst en 15450:2008 standard. equation (3) cannot be applied for calculating primary energy since the physical meaning of its multiplier )11( spf  is as follows: amountenergythermal amountpowerelectricamountenergythermal amountpowerelectric amountenergythermalspf    1 1 1 1  (4) to perform statistical calculations the h hp values have to be estimated in accordance with the data given in the guidelines 2013/114/eu of the european commission that are linked to the climate conditions of the respective eu member state. thus, depending on the climate conditions and the type of journal of sustainable architecture and civil engineering 2015/2/11 44 a heat pump, fixed h hp values unrelated to the energy needs of a building were determined in the corresponding climate zones. the 2010/31/eu directive requires estimating the energy performance of buildings in regard to the primary energy input, whereas equation (2), given in 2013/114/eu, enables estimating “the part of renewable energy generated by heat pumps” that is related neither to the requirements of the 2010/31/eu directive nor the lst en 15450:2008 standard. equation (3) cannot be applied for calculating primary energy since the physical meaning of its multiplier ) 1 1( spfη − is as follows: in equation (4), thermal and electric power cannot be taken as the same, because the latter is generated from the energy of a primary energy source (gas, oil, solid fuel, etc.). yet, electricity in not a primary energy source that is used in heat pumps to produce thermal energy. to generate electric power the eu member states use less than a half of energy available in primary energy sources. according to the data provided in the guidelines 2013/114/eu of the european commission, the average value of useful efficiency of electricity generation η el makes up 0.455 in the eu member states. consequently, if thermal and electric power were handled identically, then the impact of energy from renewable sources used in heat pumps on the calculation of the amount of energy generated from renewable sources would be reduced by 2.2 times (1/0.455=2.2) in equation (4). in that case, the calculation using equation (1) would result in an increased amount of thermal energy produced from renewable sources than it should actually be. (4) the efficiency of an electric heat pump is assessed by a seasonal performance factor ηspf that defines the ratio of the amount of thermal energy produced by a heat pump to the amount of electricity used by the pump to produce that energy. ηspf dimension can be expressed as “the amount of thermal energy”/ “the amount of electricity”. the ηspf value of a heat pump is estimated by testing in accordance with the lst en 15450:2008 (2008) standard. if the value of useful efficiency of electricity generation ηel is known (i.e. the ratio between the generated amount of electric power and the amount of energy in the energy sources used to produce that energy), the value of electric heat pump coefficient ηh.eq can be estimated as follows: elspfeqh  . (1) if (1ηh.eq)>0, the value of (1ηh.eq) indicates the amount of thermal energy present in the energy source (gas, solid fuel, etc.) that was not converted into thermal energy by that source. (1ηh.eq)<0 suggests that more thermal energy was produced while transforming the energy of a source into thermal energy than the amount of energy initially held by the energy source. in such a case, a part of energy is generated from renewable energy rather than the thermal energy initially present in the source. as follows, the value of (ηh.eq-1) defines the part of thermal energy that may be ascribed to the thermal energy generated from renewable sources and initially present in the traditional source (gas, solid fuel, etc.). the guidelines of the european commission 2013/114/eu, specifying the requirement of the eu directive 2009/28/eu to calculate the part of renewable energy generated using different technology-based heat pumps, provides a statistical method with the following equation: )11( spf usableeres ee   (2) here: eusable, the amount of energy suitable for use and supplied by heat pumps is estimated by equation (3): ratedhpusable phe  (3) here: hhp – the equivalent amount of hours of a heat pump operating at full load (h); prated – capacity of a heat pump of the respective type (kwh). to perform statistical calculations the hhp values have to be estimated in accordance with the data given in the guidelines 2013/114/eu of the european commission that are linked to the climate conditions of the respective eu member state. thus, depending on the climate conditions and the type of a heat pump, fixed hhp values unrelated to the energy needs of a building were determined in the corresponding climate zones. the 2010/31/eu directive requires estimating the energy performance of buildings in regard to the primary energy input, whereas equation (2), given in 2013/114/eu, enables estimating “the part of renewable energy generated by heat pumps” that is related neither to the requirements of the 2010/31/eu directive nor the lst en 15450:2008 standard. equation (3) cannot be applied for calculating primary energy since the physical meaning of its multiplier )11( spf  is as follows: amountenergythermal amountpowerelectricamountenergythermal amountpowerelectric amountenergythermalspf    1 1 1 1  (4) the efficiency of an electric heat pump is assessed by a seasonal performance factor ηspf that defines the ratio of the amount of thermal energy produced by a heat pump to the amount of electricity used by the pump to produce that energy. ηspf dimension can be expressed as “the amount of thermal energy”/ “the amount of electricity”. the ηspf value of a heat pump is estimated by testing in accordance with the lst en 15450:2008 (2008) standard. if the value of useful efficiency of electricity generation ηel is known (i.e. the ratio between the generated amount of electric power and the amount of energy in the energy sources used to produce that energy), the value of electric heat pump coefficient ηh.eq can be estimated as follows: elspfeqh  . (1) if (1ηh.eq)>0, the value of (1ηh.eq) indicates the amount of thermal energy present in the energy source (gas, solid fuel, etc.) that was not converted into thermal energy by that source. (1ηh.eq)<0 suggests that more thermal energy was produced while transforming the energy of a source into thermal energy than the amount of energy initially held by the energy source. in such a case, a part of energy is generated from renewable energy rather than the thermal energy initially present in the source. as follows, the value of (ηh.eq-1) defines the part of thermal energy that may be ascribed to the thermal energy generated from renewable sources and initially present in the traditional source (gas, solid fuel, etc.). the guidelines of the european commission 2013/114/eu, specifying the requirement of the eu directive 2009/28/eu to calculate the part of renewable energy generated using different technology-based heat pumps, provides a statistical method with the following equation: )11( spf usableeres ee   (2) here: eusable, the amount of energy suitable for use and supplied by heat pumps is estimated by equation (3): ratedhpusable phe  (3) here: hhp – the equivalent amount of hours of a heat pump operating at full load (h); prated – capacity of a heat pump of the respective type (kwh). to perform statistical calculations the hhp values have to be estimated in accordance with the data given in the guidelines 2013/114/eu of the european commission that are linked to the climate conditions of the respective eu member state. thus, depending on the climate conditions and the type of a heat pump, fixed hhp values unrelated to the energy needs of a building were determined in the corresponding climate zones. the 2010/31/eu directive requires estimating the energy performance of buildings in regard to the primary energy input, whereas equation (2), given in 2013/114/eu, enables estimating “the part of renewable energy generated by heat pumps” that is related neither to the requirements of the 2010/31/eu directive nor the lst en 15450:2008 standard. equation (3) cannot be applied for calculating primary energy since the physical meaning of its multiplier )11( spf  is as follows: amountenergythermal amountpowerelectricamountenergythermal amountpowerelectric amountenergythermalspf    1 1 1 1  (4) to calculate the amount of renewable and non-renewable energy supplied to a building by electric heat pumps, the following energy balance condition was composed: “the total amount of thermal energy supplied to the building systems” = “the amount of thermal energy generated using electric power and supplied to the building systems” + “the amount of thermal energy generated using renewable energy sources and supplied to the building systems”. the condition may be put into an equation as follows: solution to the problem (5) (6) (7) in equation (4), thermal and electric power cannot be taken as the same, because the latter is generated from the energy of a primary energy source (gas, oil, solid fuel, etc.). yet, electricity in not a primary energy source that is used in heat pumps to produce thermal energy. to generate electric power the eu member states use less than a half of energy available in primary energy sources. according to the data provided in the guidelines 2013/114/eu of the european commission, the average value of useful efficiency of electricity generation ηel makes up 0.455 in the eu member states. consequently, if thermal and electric power were handled identically, then the impact of energy from renewable sources used in heat pumps on the calculation of the amount of energy generated from renewable sources would be reduced by 2.2 times (1/0.455=2.2) in equation (4). in that case, the calculation using equation (1) would result in an increased amount of thermal energy produced from renewable sources than it should actually be. solution to the problem to calculate the amount of renewable and non-renewable energy supplied to a building by electric heat pumps, the following energy balance condition was composed: “the total amount of thermal energy supplied to the building systems” = “the amount of thermal energy generated using electric power and supplied to the building systems” + “the amount of thermal energy generated using renewable energy sources and supplied to the building systems”. the condition may be put into an equation as follows: eres eqh usable usable e e e  . (5) hence, the amount of thermal energy from renewable energy sources used in a building may be estimated in such a manner: ) 1 1( .. eqh usable eqh usable usableeres e e ee   (6) similarly, the energy supplied to a building from electric heat pumps is expressed as in equation (7): ) 1 1( elspf usableeres ee    (7) table 1 presents the comparison of the calculations performed using equations (2) and (7). the analysis discusses the calculation results of thermal energy produced using renewable sources in electric heat pumps per one kwh of thermal energy supplied by the pumps to the building systems. table 1. comparison of thermal energy calculations according to formulas/equations (2) and (7) the amount of thermal energy from renewable sources used in buildings obtained following equation (1) is from 1.43 to 4.96 times higher (table 1, column 5) than that obtained by equation (7). this is because equation (1) does not take into account the thermal energy of energy sources used to generate electricity. if the thermal energy used by energy sources to generate electric power is not estimated, the value of the ratio between “renewable/non-renewable thermal energy” achieved using low-efficiency heat no. heat pump ηspf, unit. amount of energy from renewable sources by equation (7), kwh amount of energy from renewable sources by equation (2), kwh calculation difference in the amount of renewable energy, times [column 4/ (column 3] amount of energy from nonrenewable sources by equation (7), kwh amount of energy from non-renewable sources by equation (2), kwh ratio “renewable/ nonrenewable” energy calculated by equation (7) ratio “renewable/ non-renewable” energy calculated by equation (2) 1 2 3 4 5 6 7 8 9 1. 2.5 0.121 0.600 4.964 0.879 0.400 0.138 1.500 2. 3.2 0.313 0.688 2.195 0.687 0.313 0.456 2.200 3. 3.5 0.372 0.714 1.920 0.628 0.286 0.593 2.500 4. 4.5 0.512 0.778 1.520 0.488 0.222 1.048 3.500 5. 5 0.560 0.800 1.427 0.440 0.200 1.275 4.000 hence, the amount of thermal energy from renewable energy sources used in a building may be estimated in such a manner: in equation (4), thermal and electric power cannot be taken as the same, because the latter is generated from the energy of a primary energy source (gas, oil, solid fuel, etc.). yet, electricity in not a primary energy source that is used in heat pumps to produce thermal energy. to generate electric power the eu member states use less than a half of energy available in primary energy sources. according to the data provided in the guidelines 2013/114/eu of the european commission, the average value of useful efficiency of electricity generation ηel makes up 0.455 in the eu member states. consequently, if thermal and electric power were handled identically, then the impact of energy from renewable sources used in heat pumps on the calculation of the amount of energy generated from renewable sources would be reduced by 2.2 times (1/0.455=2.2) in equation (4). in that case, the calculation using equation (1) would result in an increased amount of thermal energy produced from renewable sources than it should actually be. solution to the problem to calculate the amount of renewable and non-renewable energy supplied to a building by electric heat pumps, the following energy balance condition was composed: “the total amount of thermal energy supplied to the building systems” = “the amount of thermal energy generated using electric power and supplied to the building systems” + “the amount of thermal energy generated using renewable energy sources and supplied to the building systems”. the condition may be put into an equation as follows: eres eqh usable usable e e e  . (5) hence, the amount of thermal energy from renewable energy sources used in a building may be estimated in such a manner: ) 1 1( .. eqh usable eqh usable usableeres e e ee   (6) similarly, the energy supplied to a building from electric heat pumps is expressed as in equation (7): ) 1 1( elspf usableeres ee    (7) table 1 presents the comparison of the calculations performed using equations (2) and (7). the analysis discusses the calculation results of thermal energy produced using renewable sources in electric heat pumps per one kwh of thermal energy supplied by the pumps to the building systems. table 1. comparison of thermal energy calculations according to formulas/equations (2) and (7) the amount of thermal energy from renewable sources used in buildings obtained following equation (1) is from 1.43 to 4.96 times higher (table 1, column 5) than that obtained by equation (7). this is because equation (1) does not take into account the thermal energy of energy sources used to generate electricity. if the thermal energy used by energy sources to generate electric power is not estimated, the value of the ratio between “renewable/non-renewable thermal energy” achieved using low-efficiency heat no. heat pump ηspf, unit. amount of energy from renewable sources by equation (7), kwh amount of energy from renewable sources by equation (2), kwh calculation difference in the amount of renewable energy, times [column 4/ (column 3] amount of energy from nonrenewable sources by equation (7), kwh amount of energy from non-renewable sources by equation (2), kwh ratio “renewable/ nonrenewable” energy calculated by equation (7) ratio “renewable/ non-renewable” energy calculated by equation (2) 1 2 3 4 5 6 7 8 9 1. 2.5 0.121 0.600 4.964 0.879 0.400 0.138 1.500 2. 3.2 0.313 0.688 2.195 0.687 0.313 0.456 2.200 3. 3.5 0.372 0.714 1.920 0.628 0.286 0.593 2.500 4. 4.5 0.512 0.778 1.520 0.488 0.222 1.048 3.500 5. 5 0.560 0.800 1.427 0.440 0.200 1.275 4.000 similarly, the energy supplied to a building from electric heat pumps is expressed as in equation (7): in equation (4), thermal and electric power cannot be taken as the same, because the latter is generated from the energy of a primary energy source (gas, oil, solid fuel, etc.). yet, electricity in not a primary energy source that is used in heat pumps to produce thermal energy. to generate electric power the eu member states use less than a half of energy available in primary energy sources. according to the data provided in the guidelines 2013/114/eu of the european commission, the average value of useful efficiency of electricity generation ηel makes up 0.455 in the eu member states. consequently, if thermal and electric power were handled identically, then the impact of energy from renewable sources used in heat pumps on the calculation of the amount of energy generated from renewable sources would be reduced by 2.2 times (1/0.455=2.2) in equation (4). in that case, the calculation using equation (1) would result in an increased amount of thermal energy produced from renewable sources than it should actually be. solution to the problem to calculate the amount of renewable and non-renewable energy supplied to a building by electric heat pumps, the following energy balance condition was composed: “the total amount of thermal energy supplied to the building systems” = “the amount of thermal energy generated using electric power and supplied to the building systems” + “the amount of thermal energy generated using renewable energy sources and supplied to the building systems”. the condition may be put into an equation as follows: eres eqh usable usable e e e  . (5) hence, the amount of thermal energy from renewable energy sources used in a building may be estimated in such a manner: ) 1 1( .. eqh usable eqh usable usableeres e e ee   (6) similarly, the energy supplied to a building from electric heat pumps is expressed as in equation (7): ) 1 1( elspf usableeres ee    (7) table 1 presents the comparison of the calculations performed using equations (2) and (7). the analysis discusses the calculation results of thermal energy produced using renewable sources in electric heat pumps per one kwh of thermal energy supplied by the pumps to the building systems. table 1. comparison of thermal energy calculations according to formulas/equations (2) and (7) the amount of thermal energy from renewable sources used in buildings obtained following equation (1) is from 1.43 to 4.96 times higher (table 1, column 5) than that obtained by equation (7). this is because equation (1) does not take into account the thermal energy of energy sources used to generate electricity. if the thermal energy used by energy sources to generate electric power is not estimated, the value of the ratio between “renewable/non-renewable thermal energy” achieved using low-efficiency heat no. heat pump ηspf, unit. amount of energy from renewable sources by equation (7), kwh amount of energy from renewable sources by equation (2), kwh calculation difference in the amount of renewable energy, times [column 4/ (column 3] amount of energy from nonrenewable sources by equation (7), kwh amount of energy from non-renewable sources by equation (2), kwh ratio “renewable/ nonrenewable” energy calculated by equation (7) ratio “renewable/ non-renewable” energy calculated by equation (2) 1 2 3 4 5 6 7 8 9 1. 2.5 0.121 0.600 4.964 0.879 0.400 0.138 1.500 2. 3.2 0.313 0.688 2.195 0.687 0.313 0.456 2.200 3. 3.5 0.372 0.714 1.920 0.628 0.286 0.593 2.500 4. 4.5 0.512 0.778 1.520 0.488 0.222 1.048 3.500 5. 5 0.560 0.800 1.427 0.440 0.200 1.275 4.000 45 journal of sustainable architecture and civil engineering 2015/2/11 table 1 presents the comparison of the calculations performed using equations (2) and (7). the analysis discusses the calculation results of thermal energy produced using renewable sources in electric heat pumps per one kwh of thermal energy supplied by the pumps to the building systems. the amount of thermal energy from renewable sources used in buildings obtained following equation (1) is from 1.43 to 4.96 times higher (table 1, column 5) than that obtained by equation (7). this is because equation (1) does not take into account the thermal energy of energy sources used to generate electricity. table 1 comparison of thermal energy calculations according to formulas/ equations (2) and (7) n o . h ea t pu m p η s p f, u ni t. a m o u nt o f en er g y fr o m re ne w ab le s o u rc es b y eq u ati o n (7 ), k w h a m o u nt o f en er g y fr o m re ne w ab le s o u rc es b y eq u ati o n (2 ), k w h c al cu la ti o n di ff er en ce in th e am o u nt o f re ne w ab le en er g y, t im es [c o lu m n 4/ ( co lu m n 3] a m o u nt o f en er g y fr o m no nre ne w ab le s o u rc es b y eq u at io n (7 ), k w h a m o u nt o f en er g y fr o m no nre ne w ab le s o u rc es b y eq u at io n (2 ), k w h r at io “ re ne w ab le / no nre ne w ab le ” en er g y ca lc u la te d by e q u at io n (7 ) r at io “ re ne w ab le / no nre ne w ab le ” en er g y ca lc u la te d by e q u at io n (2 ) 1 2 3 4 5 6 7 8 9 1. 2.5 0.121 0.600 4.964 0.879 0.400 0.138 1.500 2. 3.2 0.313 0.688 2.195 0.687 0.313 0.456 2.200 3. 3.5 0.372 0.714 1.920 0.628 0.286 0.593 2.500 4. 4.5 0.512 0.778 1.520 0.488 0.222 1.048 3.500 5. 5 0.560 0.800 1.427 0.440 0.200 1.275 4.000 if the thermal energy used by energy sources to generate electric power is not estimated, the value of the ratio between “renewable/non-renewable thermal energy” achieved using low-efficiency heat pumps (η spf =2.5) is 1.5, and when η spf =5, the value makes up as much as 4.0 (table 1, column 9). analogous calculation by equation (7) demonstrates that the value of the ratio “renewable/non-renewable thermal energy” makes up as little as from 0.138 to 1.275 (table 1, column 8). the calculation of renewable/non-renewable primary energy of electric heat pumps is related to the values of primary energy factors from electric power. the estimation of these values takes into account the amount of renewable/non-renewable primary energy used by all energy sources to generate electricity, renewable/non-renewable primary energy input for energy transportation, and primary energy losses in electricity networks. in this case, the values of primary energy factors cover not only energy sources, but also the value of useful efficiency of electricity generation η el and the losses in electricity transportation. the lithuanian normative documents in construction assume that for the calculation of electric power input in buildings electric power supplied from electricity networks is f prr =0 and f prn =2.8. the amount of non-renewable primary energy supplied to the building systems by heat pumps used therein to generate thermal energy from electric power may be estimated as follows: (8) pumps (ηspf =2.5) is 1.5, and when ηspf =5, the value makes up as much as 4.0 (table 1, column 9). analogous calculation by equation (7) demonstrates that the value of the ratio “renewable/nonrenewable thermal energy” makes up as little as from 0.138 to 1.275 (table 1, column 8). the calculation of renewable/non-renewable primary energy of electric heat pumps is related to the values of primary energy factors from electric power. the estimation of these values takes into account the amount of renewable/non-renewable primary energy used by all energy sources to generate electricity, renewable/non-renewable primary energy input for energy transportation, and primary energy losses in electricity networks. in this case, the values of primary energy factors cover not only energy sources, but also the value of useful efficiency of electricity generation ηel and the losses in electricity transportation. the lithuanian normative documents in construction assume that for the calculation of electric power input in buildings electric power supplied from electricity networks is fprr =0 and fprn =2.8. the amount of non-renewable primary energy supplied to the building systems by heat pumps used therein to generate thermal energy from electric power may be estimated as follows: totalyelectricit spf usable e e _ (8) usablewindpvhydrosourcerenfromyelectricittotalyelectricit eee  ),,(____ (9) here: eelectricity_total – total amount of electricity, consumed by heat pumps. eelectricity from ren source (hydro, pv, wind) – amount of electricity from renewable sources (hydro, pv, wind). prnel spf usable prn f e e .  (10) the amount of renewable primary energy, supplied by electric heat pumps to the building systems, includes the renewable primary energy of electric power consumed in the pumps and the energy of renewable sources, calculated by equation (7). this amount may be estimated as follows: ),,(___.. ) 1 1( windpvhydrosourcerenfromyelectricitprrhp elspf usableprrel spf usable prr efef e e     (11) here: fel.prn – non-renewable primary energy factors from electric power (unit), which is accepted here as fel.prn =2.8 in calculating; fel.prr – renewable primary energy factors from electric power (unit). in the present calculations it is accepted that fel.prr =0, but renewable energy sources may also be used for generating electricity and for this reason, fel.prr may be >0. for example, if electricity from hydro power plants is used, then fel.prr =1, fel.prn =0.5. electricity from pv power plant is used, then fel.prr =1, fel.prn =0.7; electricity from wind power plant is used, then fel.prr =1, fel.prn =0.3; fhp.prr – renewable primary energy factors from heat pumps (unit). according to the order determined by the lst en 15450:2008 standard, renewable primary energy fhp.prr =1. table 2 provides the calculation results of primary energy per one kwh to the amount of thermal energy supplied by heat pumps to the building systems; i.e. when eusable=1 kwh, according to equations (10) and (11). table 2. primary energy supplied from electric heat pumps calculated according to equations (10) and (11) no. heat pump ηspf, unit amount of nonrenewable primary energy by equations (8), eprn, kwh amount of renewable primary energy by equations (9), eprr, kwh ratio eprr/eprn 1 2 3 4 5 1. 2.5 1.120 0.121 0.108 2. 3.2 0.875 0.313 0.358 3. 3.5 0.800 0.372 0.465 4. 4.5 0.622 0.512 0.822 5. 5 0.560 0.560 1.001 journal of sustainable architecture and civil engineering 2015/2/11 46 tems, includes the renewable primary energy of electric power consumed in the pumps and the energy of renewable sources, calculated by equation (7). this amount may be estimated as follows: table 2 primary energy supplied from electric heat pumps calculated according to equations (10) and (11) no. heat pump η spf , unit amount of non-renewable primary energy by equations (8), e prn , kwh amount of renewable primary energy by equations (9), e prr , kwh ratio e prr /e prn 1 2 3 4 5 1. 2.5 1.120 0.121 0.108 2. 3.2 0.875 0.313 0.358 3. 3.5 0.800 0.372 0.465 4. 4.5 0.622 0.512 0.822 5. 5 0.560 0.560 1.001 here: e electricity_total – total amount of electricity, consumed by heat pumps. e electricity from ren source (hydro, pv, wind) – amount of electricity from renewable sources (hydro, pv, wind). the amount of renewable primary energy, supplied by electric heat pumps to the building sys(9) (11) pumps (ηspf =2.5) is 1.5, and when ηspf =5, the value makes up as much as 4.0 (table 1, column 9). analogous calculation by equation (7) demonstrates that the value of the ratio “renewable/nonrenewable thermal energy” makes up as little as from 0.138 to 1.275 (table 1, column 8). the calculation of renewable/non-renewable primary energy of electric heat pumps is related to the values of primary energy factors from electric power. the estimation of these values takes into account the amount of renewable/non-renewable primary energy used by all energy sources to generate electricity, renewable/non-renewable primary energy input for energy transportation, and primary energy losses in electricity networks. in this case, the values of primary energy factors cover not only energy sources, but also the value of useful efficiency of electricity generation ηel and the losses in electricity transportation. the lithuanian normative documents in construction assume that for the calculation of electric power input in buildings electric power supplied from electricity networks is fprr =0 and fprn =2.8. the amount of non-renewable primary energy supplied to the building systems by heat pumps used therein to generate thermal energy from electric power may be estimated as follows: totalyelectricit spf usable e e _ (8) usablewindpvhydrosourcerenfromyelectricittotalyelectricit eee  ),,(____ (9) here: eelectricity_total – total amount of electricity, consumed by heat pumps. eelectricity from ren source (hydro, pv, wind) – amount of electricity from renewable sources (hydro, pv, wind). prnel spf usable prn f e e .  (10) the amount of renewable primary energy, supplied by electric heat pumps to the building systems, includes the renewable primary energy of electric power consumed in the pumps and the energy of renewable sources, calculated by equation (7). this amount may be estimated as follows: ),,(___.. ) 1 1( windpvhydrosourcerenfromyelectricitprrhp elspf usableprrel spf usable prr efef e e     (11) here: fel.prn – non-renewable primary energy factors from electric power (unit), which is accepted here as fel.prn =2.8 in calculating; fel.prr – renewable primary energy factors from electric power (unit). in the present calculations it is accepted that fel.prr =0, but renewable energy sources may also be used for generating electricity and for this reason, fel.prr may be >0. for example, if electricity from hydro power plants is used, then fel.prr =1, fel.prn =0.5. electricity from pv power plant is used, then fel.prr =1, fel.prn =0.7; electricity from wind power plant is used, then fel.prr =1, fel.prn =0.3; fhp.prr – renewable primary energy factors from heat pumps (unit). according to the order determined by the lst en 15450:2008 standard, renewable primary energy fhp.prr =1. table 2 provides the calculation results of primary energy per one kwh to the amount of thermal energy supplied by heat pumps to the building systems; i.e. when eusable=1 kwh, according to equations (10) and (11). table 2. primary energy supplied from electric heat pumps calculated according to equations (10) and (11) no. heat pump ηspf, unit amount of nonrenewable primary energy by equations (8), eprn, kwh amount of renewable primary energy by equations (9), eprr, kwh ratio eprr/eprn 1 2 3 4 5 1. 2.5 1.120 0.121 0.108 2. 3.2 0.875 0.313 0.358 3. 3.5 0.800 0.372 0.465 4. 4.5 0.622 0.512 0.822 5. 5 0.560 0.560 1.001 (10) pumps (ηspf =2.5) is 1.5, and when ηspf =5, the value makes up as much as 4.0 (table 1, column 9). analogous calculation by equation (7) demonstrates that the value of the ratio “renewable/nonrenewable thermal energy” makes up as little as from 0.138 to 1.275 (table 1, column 8). the calculation of renewable/non-renewable primary energy of electric heat pumps is related to the values of primary energy factors from electric power. the estimation of these values takes into account the amount of renewable/non-renewable primary energy used by all energy sources to generate electricity, renewable/non-renewable primary energy input for energy transportation, and primary energy losses in electricity networks. in this case, the values of primary energy factors cover not only energy sources, but also the value of useful efficiency of electricity generation ηel and the losses in electricity transportation. the lithuanian normative documents in construction assume that for the calculation of electric power input in buildings electric power supplied from electricity networks is fprr =0 and fprn =2.8. the amount of non-renewable primary energy supplied to the building systems by heat pumps used therein to generate thermal energy from electric power may be estimated as follows: totalyelectricit spf usable e e _ (8) usablewindpvhydrosourcerenfromyelectricittotalyelectricit eee  ),,(____ (9) here: eelectricity_total – total amount of electricity, consumed by heat pumps. eelectricity from ren source (hydro, pv, wind) – amount of electricity from renewable sources (hydro, pv, wind). prnel spf usable prn f e e .  (10) the amount of renewable primary energy, supplied by electric heat pumps to the building systems, includes the renewable primary energy of electric power consumed in the pumps and the energy of renewable sources, calculated by equation (7). this amount may be estimated as follows: ),,(___.. ) 1 1( windpvhydrosourcerenfromyelectricitprrhp elspf usableprrel spf usable prr efef e e     (11) here: fel.prn – non-renewable primary energy factors from electric power (unit), which is accepted here as fel.prn =2.8 in calculating; fel.prr – renewable primary energy factors from electric power (unit). in the present calculations it is accepted that fel.prr =0, but renewable energy sources may also be used for generating electricity and for this reason, fel.prr may be >0. for example, if electricity from hydro power plants is used, then fel.prr =1, fel.prn =0.5. electricity from pv power plant is used, then fel.prr =1, fel.prn =0.7; electricity from wind power plant is used, then fel.prr =1, fel.prn =0.3; fhp.prr – renewable primary energy factors from heat pumps (unit). according to the order determined by the lst en 15450:2008 standard, renewable primary energy fhp.prr =1. table 2 provides the calculation results of primary energy per one kwh to the amount of thermal energy supplied by heat pumps to the building systems; i.e. when eusable=1 kwh, according to equations (10) and (11). table 2. primary energy supplied from electric heat pumps calculated according to equations (10) and (11) no. heat pump ηspf, unit amount of nonrenewable primary energy by equations (8), eprn, kwh amount of renewable primary energy by equations (9), eprr, kwh ratio eprr/eprn 1 2 3 4 5 1. 2.5 1.120 0.121 0.108 2. 3.2 0.875 0.313 0.358 3. 3.5 0.800 0.372 0.465 4. 4.5 0.622 0.512 0.822 5. 5 0.560 0.560 1.001 here: f el.prn – non-renewable primary energy factors from electric power (unit), which is accepted here as f el.prn =2.8 in calculating; f el.prr – renewable primary energy factors from electric power (unit). in the present calculations it is accepted that f el.prr =0, but renewable energy sources may also be used for generating electricity and for this reason, f el.prr may be >0. for example, if electricity from hydro power plants is used, then f el.prr =1, f el.prn =0.5. electricity from pv power plant is used, then f el.prr =1, f el.prn =0.7; electricity from wind power plant is used, then f el.prr =1, f el.prn =0.3; f hp.prr – renewable primary energy factors from heat pumps (unit). according to the order determined by the lst en 15450:2008 standard, renewable primary energy f hp.prr =1. table 2 provides the calculation results of primary energy per one kwh to the amount of thermal energy supplied by heat pumps to the building systems; i.e. when e usable =1 kwh, according to equations (10) and (11). the calculations show that when f el.prn =2.8, f el.prr =0 and η el =0.455, the ratio of renewable and non-renewable energy supplied by electric heat pumps to a building e prr /e prn =1 can only be achieved when heat pumps η spf ≥5 (table 2, line 5). the calculation of renewable and non-renewable energy ratio by equation (2) given in the 2009/28/ eu directive and the guidelines 2013/114/eu of the european commission (table 1, column 9) is different from the calculation results of renewable/non-renewable energy ratio presented herein (table 2, column 5) by 4 to 14 times. pumps (ηspf =2.5) is 1.5, and when ηspf =5, the value makes up as much as 4.0 (table 1, column 9). analogous calculation by equation (7) demonstrates that the value of the ratio “renewable/nonrenewable thermal energy” makes up as little as from 0.138 to 1.275 (table 1, column 8). the calculation of renewable/non-renewable primary energy of electric heat pumps is related to the values of primary energy factors from electric power. the estimation of these values takes into account the amount of renewable/non-renewable primary energy used by all energy sources to generate electricity, renewable/non-renewable primary energy input for energy transportation, and primary energy losses in electricity networks. in this case, the values of primary energy factors cover not only energy sources, but also the value of useful efficiency of electricity generation ηel and the losses in electricity transportation. the lithuanian normative documents in construction assume that for the calculation of electric power input in buildings electric power supplied from electricity networks is fprr =0 and fprn =2.8. the amount of non-renewable primary energy supplied to the building systems by heat pumps used therein to generate thermal energy from electric power may be estimated as follows: totalyelectricit spf usable e e _ (8) usablewindpvhydrosourcerenfromyelectricittotalyelectricit eee  ),,(____ (9) here: eelectricity_total – total amount of electricity, consumed by heat pumps. eelectricity from ren source (hydro, pv, wind) – amount of electricity from renewable sources (hydro, pv, wind). prnel spf usable prn f e e .  (10) the amount of renewable primary energy, supplied by electric heat pumps to the building systems, includes the renewable primary energy of electric power consumed in the pumps and the energy of renewable sources, calculated by equation (7). this amount may be estimated as follows: ),,(___.. ) 1 1( windpvhydrosourcerenfromyelectricitprrhp elspf usableprrel spf usable prr efef e e     (11) here: fel.prn – non-renewable primary energy factors from electric power (unit), which is accepted here as fel.prn =2.8 in calculating; fel.prr – renewable primary energy factors from electric power (unit). in the present calculations it is accepted that fel.prr =0, but renewable energy sources may also be used for generating electricity and for this reason, fel.prr may be >0. for example, if electricity from hydro power plants is used, then fel.prr =1, fel.prn =0.5. electricity from pv power plant is used, then fel.prr =1, fel.prn =0.7; electricity from wind power plant is used, then fel.prr =1, fel.prn =0.3; fhp.prr – renewable primary energy factors from heat pumps (unit). according to the order determined by the lst en 15450:2008 standard, renewable primary energy fhp.prr =1. table 2 provides the calculation results of primary energy per one kwh to the amount of thermal energy supplied by heat pumps to the building systems; i.e. when eusable=1 kwh, according to equations (10) and (11). table 2. primary energy supplied from electric heat pumps calculated according to equations (10) and (11) no. heat pump ηspf, unit amount of nonrenewable primary energy by equations (8), eprn, kwh amount of renewable primary energy by equations (9), eprr, kwh ratio eprr/eprn 1 2 3 4 5 1. 2.5 1.120 0.121 0.108 2. 3.2 0.875 0.313 0.358 3. 3.5 0.800 0.372 0.465 4. 4.5 0.622 0.512 0.822 5. 5 0.560 0.560 1.001 47 journal of sustainable architecture and civil engineering 2015/2/11 table 3 gives the 2011 data on the f prn values of electric power used for calculation in the building standards of some eu members. the pumps that are most often used to heat buildings and water are soil-water heat pumps with η spf target value of 4.0 for new buildings in central europe. table 4 gives the calculation results of e prr /e prn (per 1 kwh of thermal energy supplied by heat pumps to the building systems, by formulas/equations (8) and (9)) in electric heat pumps with η spf = 4 in the eu members given in table 3 and lithuania, as well as the η spf values of electric heat pumps that enable achieving e prr /e prn =1 in the mentioned countable 3 f prn values of electric power in the building standards of the eu members country f prn france 2.58 germany 2.60 holland 2.56 poland 3.00 spain 2.60 sweden 2.00 the united kingdom 2.92 tries. to perform the calculation the average value of useful efficiency of electricity generation η el that makes up 0.455, and f el.prr =0 was applied. as the data in table 4 shows, in all the countries discussed except sweden, the ratio of thermal energy supplied by electric heat pumps to a building e prr /e prn =1 can be achieved by very high-efficiency pumps with η spf value varying between 4.8 and 5.2, while in sweden the same ratio can be reached with pumps having η spf =4.2. analogous results were obtained having performed calculations on electric heat pumps applied for cooling buildings. in this case, the value η spf was replaced no. eu member heat pump η spf , unit amount of non-renewable primary energy by equation (8), e prn , kwh amount of renewable primary energy by equation (9), e prr , kwh ratio e prr /e prn 1 2 3 4 5 6 1 france 4.0 0.645 0.451 0.699 2 4.8 0.538 0.542 1.009 3 germany 4.0 0.650 0.451 0.693 4 4.8 0.542 0.542 1.001 5 holland 4.0 0.640 0.451 0.704 6 4.8 0.533 0.542 1.016 7 poland 4.0 0.750 0.451 0.601 8 5.2 0.577 0.577 1.001 9 spain 4.0 0.650 0.451 0.693 10 4.8 0.542 0.542 1.001 11 sweden 4.0 0.500 0.451 0.901 12 4.2 0.476 0.477 1.001 13 the united kingdom 4.0 0.730 0.451 0.617 14 5.2 0.562 0.577 1.028 15 lithuania 4.0 0.700 0.451 0.644 16 5.0 0.560 0.560 1.001 table 4 comparison of e prr and e prn per 1 kwh of thermal energy supplied by electric heat pumps to a building in different eu members journal of sustainable architecture and civil engineering 2015/2/11 48 with η eer in the calculations in table 2. to cool a building air-air electric heat pumps with η eer target value of 2.8 are usually used, whereas soil pumps with η eer target value of 3.8, and water pumps with η eer target value of 4.3 are rarely used for the same purpose. in this case, the ratio e prr /e prn =1 can be achieved by using the pumps of considerably higher η eer values. such a striking distinction in the calculation results obtained by equations (2) and (7) poses a question on the difference between the assessments of renewable energy generated by a heat pump for heating a building according to 2013/114/eu directive and the method proposed in this paper. for the present analysis, a low thermal capacity single-flat building with 100 m² of heated area satisfying the requirements of b energy performance label (according to str 2.01.09:2012) was selected; the building has the following parameters: _ energy input for heating: 383•a p -0,22=383•100-0,22 = 139 kwh/m² annually; _ soil-water heat pump with η spf =3.5; _ average temperature of premises during heating season: 20 ºc; _ average outdoor temperature during heating season: 0.6 ºc‘ _ duration of heating season: 220 days. to heat a low thermal capacity building in the lithuanian climate conditions the heat pump power p rated (kwh) is determined at -27 ºc temperature with a reserve coefficient of 1.1; thus, the approximate calculation can be done in the following manner: 1.1*(139 kwh/m² annually)*(100 m²)/(220 days)*(24 h)*(20 ºc+27 ºc)/(20 ºc-0,6 ºc)=7 kw. to generate (139 kwh/m²)*(100 m²)=13900 kwh of energy annually a 7 kw capacity heat source should be in operation at full capacity and optimal performance for (13900 kwh)/(7 kw)=1986 h. however, the heat pump does not operate at full capacity during the whole operational period, which is why the actual operational period becomes longer. in table 1, the 2013/114/eu method provides for 1.25 times higher heat pump operational cost for cold climate zones making up 2470 h in total. therefore, according to this method, the amount of renewable energy generated by the heat pump annually is as follows: (12) (13) (14) ηeer target value of 2.8 are usually used, whereas soil pumps with ηeer target value of 3.8, and water pumps with ηeer target value of 4.3 are rarely used for the same purpose. in this case, the ratio eprr/eprn=1 can be achieved by using the pumps of considerably higher ηeer values. such a striking distinction in the calculation results obtained by equations (2) and (7) poses a question on the difference between the assessments of renewable energy generated by a heat pump for heating a building according to 2013/114/eu directive and the method proposed in this paper. for the present analysis, a low thermal capacity single-flat building with 100 m² of heated area satisfying the requirements of b energy performance label (according to str 2.01.09:2012) was selected; the building has the following parameters: energy input for heating: 383•ap-0,22=383•100-0,22 = 139 kwh/m² annually; soil-water heat pump with ηspf =3.5; average temperature of premises during heating season: 20 ºc; average outdoor temperature during heating season: 0.6 ºc‘ duration of heating season: 220 days. to heat a low thermal capacity building in the lithuanian climate conditions the heat pump power prated (kwh) is determined at -27 ºc temperature with a reserve coefficient of 1.1; thus, the approximate calculation can be done in the following manner: 1.1*(139 kwh/m² annually)*(100 m²)/(220 days)*(24 h)*(20 ºc+27 ºc)/(20 ºc-0,6 ºc)=7 kw. to generate (139 kwh/m²)*(100 m²)=13900 kwh of energy annually a 7 kw capacity heat source should be in operation at full capacity and optimal performance for (13900 kwh)/(7 kw)=1986 h. however, the heat pump does not operate at full capacity during the whole operational period, which is why the actual operational period becomes longer. in table 1, the 2013/114/eu method provides for 1.25 times higher heat pump operational cost for cold climate zones making up 2470 h in total. therefore, according to this method, the amount of renewable energy generated by the heat pump annually is as follows: 1729024707  ratedhpusable phe (12) 12350 53 1 117290 1 1  ) . ()(ee spf usableeres  (13) according to equation (7), if the heat pump supplied 17290 kwh of thermal energy annually, the following results of renewable energy calculation would be obtained: 6433 455053 1 117290 1 1      ) .. ()(ee elspf usableeres  (14) the results of the analysis showed that the 2013/114/eu method for renewable energy calculation does not take into account the primary energy input for transforming electric power. therefore, the calculated amount of renewable energy generated by heat pumps is higher than it should be. conclusions all renewable energy sources contain some non-renewable energy and for this reason, the requirement of the 2010/31/eu directive, stating that more than a half of the amount of energy used by nearly zero-energy buildings should come from renewable energy sources, can only be related to the amounts of renewable and non-renewable primary energy used in the buildings, rather than energy in general, i.e. generated using renewable and non-renewable sources. the requirement of the 2010/31/eu directive on the energy performance of buildings to calculate the amount of energy from renewable energy sources for nearly zero-energy buildings following the according to equation (7), if the heat pump supplied 17290 kwh of thermal energy annually, the following results of renewable energy calculation would be obtained: ηeer target value of 2.8 are usually used, whereas soil pumps with ηeer target value of 3.8, and water pumps with ηeer target value of 4.3 are rarely used for the same purpose. in this case, the ratio eprr/eprn=1 can be achieved by using the pumps of considerably higher ηeer values. such a striking distinction in the calculation results obtained by equations (2) and (7) poses a question on the difference between the assessments of renewable energy generated by a heat pump for heating a building according to 2013/114/eu directive and the method proposed in this paper. for the present analysis, a low thermal capacity single-flat building with 100 m² of heated area satisfying the requirements of b energy performance label (according to str 2.01.09:2012) was selected; the building has the following parameters: energy input for heating: 383•ap-0,22=383•100-0,22 = 139 kwh/m² annually; soil-water heat pump with ηspf =3.5; average temperature of premises during heating season: 20 ºc; average outdoor temperature during heating season: 0.6 ºc‘ duration of heating season: 220 days. to heat a low thermal capacity building in the lithuanian climate conditions the heat pump power prated (kwh) is determined at -27 ºc temperature with a reserve coefficient of 1.1; thus, the approximate calculation can be done in the following manner: 1.1*(139 kwh/m² annually)*(100 m²)/(220 days)*(24 h)*(20 ºc+27 ºc)/(20 ºc-0,6 ºc)=7 kw. to generate (139 kwh/m²)*(100 m²)=13900 kwh of energy annually a 7 kw capacity heat source should be in operation at full capacity and optimal performance for (13900 kwh)/(7 kw)=1986 h. however, the heat pump does not operate at full capacity during the whole operational period, which is why the actual operational period becomes longer. in table 1, the 2013/114/eu method provides for 1.25 times higher heat pump operational cost for cold climate zones making up 2470 h in total. therefore, according to this method, the amount of renewable energy generated by the heat pump annually is as follows: 1729024707  ratedhpusable phe (12) 12350 53 1 117290 1 1  ) . ()(ee spf usableeres  (13) according to equation (7), if the heat pump supplied 17290 kwh of thermal energy annually, the following results of renewable energy calculation would be obtained: 6433 455053 1 117290 1 1      ) .. ()(ee elspf usableeres  (14) the results of the analysis showed that the 2013/114/eu method for renewable energy calculation does not take into account the primary energy input for transforming electric power. therefore, the calculated amount of renewable energy generated by heat pumps is higher than it should be. conclusions all renewable energy sources contain some non-renewable energy and for this reason, the requirement of the 2010/31/eu directive, stating that more than a half of the amount of energy used by nearly zero-energy buildings should come from renewable energy sources, can only be related to the amounts of renewable and non-renewable primary energy used in the buildings, rather than energy in general, i.e. generated using renewable and non-renewable sources. the requirement of the 2010/31/eu directive on the energy performance of buildings to calculate the amount of energy from renewable energy sources for nearly zero-energy buildings following the ηeer target value of 2.8 are usually used, whereas soil pumps with ηeer target value of 3.8, and water pumps with ηeer target value of 4.3 are rarely used for the same purpose. in this case, the ratio eprr/eprn=1 can be achieved by using the pumps of considerably higher ηeer values. such a striking distinction in the calculation results obtained by equations (2) and (7) poses a question on the difference between the assessments of renewable energy generated by a heat pump for heating a building according to 2013/114/eu directive and the method proposed in this paper. for the present analysis, a low thermal capacity single-flat building with 100 m² of heated area satisfying the requirements of b energy performance label (according to str 2.01.09:2012) was selected; the building has the following parameters: energy input for heating: 383•ap-0,22=383•100-0,22 = 139 kwh/m² annually; soil-water heat pump with ηspf =3.5; average temperature of premises during heating season: 20 ºc; average outdoor temperature during heating season: 0.6 ºc‘ duration of heating season: 220 days. to heat a low thermal capacity building in the lithuanian climate conditions the heat pump power prated (kwh) is determined at -27 ºc temperature with a reserve coefficient of 1.1; thus, the approximate calculation can be done in the following manner: 1.1*(139 kwh/m² annually)*(100 m²)/(220 days)*(24 h)*(20 ºc+27 ºc)/(20 ºc-0,6 ºc)=7 kw. to generate (139 kwh/m²)*(100 m²)=13900 kwh of energy annually a 7 kw capacity heat source should be in operation at full capacity and optimal performance for (13900 kwh)/(7 kw)=1986 h. however, the heat pump does not operate at full capacity during the whole operational period, which is why the actual operational period becomes longer. in table 1, the 2013/114/eu method provides for 1.25 times higher heat pump operational cost for cold climate zones making up 2470 h in total. therefore, according to this method, the amount of renewable energy generated by the heat pump annually is as follows: 1729024707  ratedhpusable phe (12) 12350 53 1 117290 1 1  ) . ()(ee spf usableeres  (13) according to equation (7), if the heat pump supplied 17290 kwh of thermal energy annually, the following results of renewable energy calculation would be obtained: 6433 455053 1 117290 1 1      ) .. ()(ee elspf usableeres  (14) the results of the analysis showed that the 2013/114/eu method for renewable energy calculation does not take into account the primary energy input for transforming electric power. therefore, the calculated amount of renewable energy generated by heat pumps is higher than it should be. conclusions all renewable energy sources contain some non-renewable energy and for this reason, the requirement of the 2010/31/eu directive, stating that more than a half of the amount of energy used by nearly zero-energy buildings should come from renewable energy sources, can only be related to the amounts of renewable and non-renewable primary energy used in the buildings, rather than energy in general, i.e. generated using renewable and non-renewable sources. the requirement of the 2010/31/eu directive on the energy performance of buildings to calculate the amount of energy from renewable energy sources for nearly zero-energy buildings following the the results of the analysis showed that the 2013/114/eu method for renewable energy calculation does not take into account the primary energy input for transforming electric power. therefore, the calculated amount of renewable energy generated by heat pumps is higher than it should be. 49 journal of sustainable architecture and civil engineering 2015/2/11 all renewable energy sources contain some non-renewable energy and for this reason, the requirement of the 2010/31/eu directive, stating that more than a half of the amount of energy used by nearly zero-energy buildings should come from renewable energy sources, can only be related to the amounts of renewable and non-renewable primary energy used in the buildings, rather than energy in general, i.e. generated using renewable and non-renewable sources. the requirement of the 2010/31/eu directive on the energy performance of buildings to calculate the amount of energy from renewable energy sources for nearly zero-energy buildings following the provisions of the 2009/28/eu directive is related to the requirement to follow the inadequate equation for estimating the amount of energy supplied by electric heat pumps to a building given therein and in the guidelines 2013/114/eu of the european commission. the application of the equation provided in the 2009/28/eu directive and the guidelines 2013/114/ eu results in the ratio values of renewable/non-renewable energy supplied by electric heat pumps to a building that are from 4 to 14 times higher than the values of renewable/non-renewable primary energy ratio. the ratio q prr /q prn =1 of renewable/non-renewable primary energy may only be achieved by using highly efficient pumps with η spf (supplying energy for heating) and η eer (supplying energy for cooling) values fluctuating between 4.8 and 5.2. finally, thermal energy is not the only type of energy consumed in buildings as quite large amounts of electric power are used for lighting and ventilation systems as well as various electric installations. hence, this suggests that merely electric heat pumps will not suffice to achieve the required amount of renewable primary energy in nearly zero-energy buildings. doing so will require to ensure the supply of energy into a building from other renewable energy sources (solar panels, wind power plants, hydro power plans, biofuel, etc.). conclusions bayera p., sanerb d., bolaya s., rybachc l., blumd p., 2012. greenhouse gas emission savings of ground source heat pump systems in europe: a review, renewable and sustainable energy reviews 16 1256–1267. http://dx.doi. org/10.1016/j.rser.2011.09.027 balta m. t., kalinci y., hepbasli a., 2008. evaluating a low exergy heating system from the power plant through the heat pump to the building envelope, journal of energy and buildings 40 1799–1804. http://dx.doi.org/10.1016/j.enbuild.2008.03.008 cabrol l., rowley p., 2012 towards low carbon homes – a simulation analysis of buildingintegrated air-source heat pump systems. journal of energy and buildings 48 127–136. http://dx.doi. org/10.1016/j.enbuild.2012.01.019 decision 2013/114/eu of the european parliament and the council of 1 march 2009 establishing the guidelines for member states on calculating renewable energy from heat pumps from different heat pump technologies pursuant to article 5 of directive2009/28/ec. official journal of the european communities 2013 03 06. l 62/27. directive 2009/28/ec of the european parliament and the council of 23 april 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing directives 2001/77/ec and 2003/30/ec. official journal of the european communities. 2009. 05 06 l 140/16. directive 2010/31/ec of the european parliament and the council of 19 may 2010 on the energy performance of building. official journal of the european communities. 2010.18.6.2010,13-35. elgendy e., schmidt j., 2014 optimum utilization of recovered heat of a gas engine heat pump used for water heating at low air temperature journal of energy and buildings 80 375–383. gea f., guoa x., hua z., chub y. 2011. energy savings potential of a desiccant assisted hybrid air source heat pump system for residential building in hot summer and cold winter zone in china, journal of energy and buildings 43 3521–3527. http://dx.doi.org/10.1016/j.enbuild.2011.09.021 havelsky v., 1999. energetic efficiency of cogeneration systems for combined heat, cold and power production international journal references journal of sustainable architecture and civil engineering 2015/2/11 50 of refrigeration 22 479-485. http://dx.doi. org/10.1016/s0140-7007(99)00010-9 hebenstreit b., schnetzinger r., ohnmacht r., hoftberger e., lundgren j., haslinger w., toffolo a., 2014.techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers journal of applied biomass and bioenergy. huchtemann k., müller d., 2012. evaluation of a field test with retrofit heat pumps, journal of building and environment 53 100-106. http:// dx.doi.org/10.1016/j.buildenv.2012.01.013 lee w.n., kim h. j., park j.b., cho k.s., roh j. h., s.yong son, 2012. economic analysis of heating and cooling systems from the various perspectives: application to ehp and ghp in korea, renewable and sustainable energy reviews 16 4116–4125. http://dx.doi.org/10.1016/j.rser.2012.03.038 li f., zheng g., tian z., 2013. optimal operation strategy of the hybrid heating system composed of centrifugal heat pumps and gas boilers, journal of energy and buildings 58 27–36. http://dx.doi. org/10.1016/j.enbuild.2012.09.044 lst en 15450:2008 pastatų šildymo sistemos. šildymo sistemų su šilumos siurbliais projektavimas [heating systems in buildings design of heat pump heating systems]. mendes l. f., collares-pereira m., ziegler f. 1998. supply of cooling and heating with solar assisted absorption heat pumps: an energetic approach. rosiek s., batlles f. j., 2013. renewable energy solutions for building cooling, heating and power system installed in an institutional building: case study in southern spain, renewable and sustainable energy reviews 26 147–168. http:// dx.doi.org/10.1016/j.rser.2013.05.068 sarbu i., sebarchievici c., 2014. general review of ground-source heat pump systems for heating and cooling of buildings journal energy and buildings 70 441–454. str 2.01.09:2012 pastatų energinis naudingumas. energinio naudingumo sertifikavimas [energy performance of buildings. energy performance certification]. vilnius: ministry of environment of the republic of lithuania, 2005. tagliafico l. a., scarpa f., tagliafico g., valsuani f., 2012. an approach to energy saving assessment of solar assisted heat pumps for swimming pool water heating, journal of energy and buildings 55 833–840. http://dx.doi.org/10.1016/j.enbuild.2012.10.009 tagliafico l., a., scarpa f., valsuani f., 2014. direct expansion solar assisted heat pumps a clean steady state approach for overall performance analysis journal of applied thermal engineering 66 216–226. teng x., wang x., chen, y., shi w., 2014 a simple method to determine the optimal gas turbine capacity and operating strategy in building cooling, heating and power system journal of applied energy and buildings. wu w., wang b., you t., shi w., li x., 2013. a potential solution for thermal imbalance of ground source heat pump systems in cold regions: ground source absorption heat pump, journal of renewable energy 59 39–48. http://dx.doi. org/10.1016/j.renene.2013.03.020 wu w., you t., wang b., shi w., li x., 2014. simulation of a combined heating, cooling and domestic hot water system based on ground source absorption heat pump journal of applied energy 126 113–122. yang s. h., rhee j. y., 2013. utilization and performance evaluation of a surplus air heat pump system for greenhouse cooling and heating, journal of applied energy 105 244–251. http:// dx.doi.org/10.1016/j.apenergy.2012.12.038 you t., wang b., wu w., shi w., li x., 2014. a new solution for underground thermal imbalance of groundcoupled heat pump systems in cold regions: heat compensation unit with thermosyphon journal of applied thermal engineering 64 283– 292. zhaon y., heng c., xi w., yiguang c., 2011. research on improving energy efficiency and the annual distributing structure in electricity and gas consumption by extending use of gehp. energy policy 39 5192–5202. http://dx.doi.org/10.1016/j. enpol.2011.05.045 zhang x., yanga z., wu x., su x., c., 2014 evaluation method of gas engine-driven heat pump water heater under the working condition of summer journal of energy and buildings 77 440–444. 51 journal of sustainable architecture and civil engineering 2015/2/11 rokas tamašauskas phd student institute of architecture and construction, of kaunas university of technology, laboratory of building physics main research area renewable energy, building energy efficiency address institute of architecture and construction of kaunas university of technology, tunelio str. 60, lt44405 kaunas, lithuania tel. +370 37 350779 e-mail: rokas.tamasauskas@ktu.edu about the authors edmundas monstvilas dr. senior researcher institute of architecture and construction, of kaunas university of technology, laboratory of building physics main research area heat transfer and thermal insulation, technical properties of thermal insulation products address institute of architecture and construction of kaunas university of technology, tunelio str. 60, lt44405 kaunas, lithuania tel. +370 37 350779 e-mail: edmundas.monstvilas@ktu.lt raimondas bliūdžius professor institute of architecture and construction, of kaunas university of technology, laboratory of building physics main research area heat transfer and thermal insulation, technical properties of thermal insulation products address institute of architecture and construction of kaunas university of technology, tunelio str. 60, lt-44405 kaunas, lithuania tel. +370 37 350779 e-mail: raimondas.bliudzius@ktu.lt karolis banionis dr. researcher institute of architecture and construction, of kaunas university of technology, laboratory of building physics main research area energy efficiency and air permeability of buildings, heat transfer and thermal insulation, thermal impacts of solar radiation address institute of architecture and construction of kaunas university of technology, tunelio str. 60, lt44405 kaunas, lithuania tel. +370 37 350779 e-mail: karolis.banionis@ktu.lt kęstutis miškinis dr. researcher institute of architecture and construction, of kaunas university of technology, laboratory of building physics main research area heat transfer and thermal insulation, building acoustics address institute of architecture and construction of kaunas university of technology, tunelio str. 60, lt-44405 kaunas, lithuania tel. +370 37 350779 e-mail: kestutis.miskinis@ktu.lt journal of sustainable architecture and civil engineering 2015/1/10 50 jsace 1/10 industrial waste and burning temperature effect to building ceramics’ properties received 2014/06/27 accepted after revision 2015/02/09 journal of sustainable architecture and civil engineering vol. 1 / no. 10 / 2015 pp. 50-57 doi 10.5755/j01.sace.10.1.7458 © kaunas university of technology ramunė žurauskienė* vilnius gediminas technical university, faculty of civil engineering sauletekio ave. 11, lt-10223 vilnius, lithuania andrius kudžma vilnius gediminas technical university, laboratory of building products technology linkmenu 28, lt-08217 vilnius, lithuania rimvydas žurauskas material users and makers association, zemynos 47-43, lt-06127 vilnius, lithuania *corresponding author: ramune.zurauskiene@vgtu.lt industrial waste and burning temperature effect to building ceramics’ properties http://dx.doi.org/10.5755/j01.sace.10.1.7458 this work contains results of building ceramics properties research. the samples were made using clay, sand and an additive, made during the making of granulated foam glass. moulding compound’s compositions were discovered using triangular diagram according the experiment planning method. samples, produced from planned forming masses, were burned in three burning temperatures: 1000, 1030 and 1050 °c using different exposure duration in higher temperatures. upon receiving the samples their physical, mechanical and structural properties were determined, as well with calculation of the prognosis of operational resistance to frost. keywords: burning temperature, ceramic, composition, experiments planning, waste. introduction at this moment in the world there are countless researches which in one way or another recommend to utilize waste in building ceramics. the waste put into ceramic forming masses aren’t only those that in high temperature sinter with building ceramics but that also burn during the burning process and removes itself from building ceramics, additionally other wastes are used that disintegrate during the burning process and the disintegration products evaporate from building ceramics (kizinievič et al. 2014). in ceramics not only can the technogenic waste be utilized but also waste from leftover energetics industry (binhussaina et al. 2014) or water treatment industry (kizinievič et al. 2013). waste formed in granulated foam glass industry still hadn’t been used in building ceramics production. with this waste there still hadn’t been any research works. this material is obtained during the production, when the cullet glass moistened with binder is not suitable for further production due to unfit size. this material is sift before reaching the furnace and is unfit for secondary use making 51 journal of sustainable architecture and civil engineering 2015/1/10 glass pellets, so it is utilized. the matrixes are materials providing grinded glass mixture binding properties, needed to form pellets and to keep their plastic strength. in this case, the used matrix is liquid glass. this waste should be attributed to microdispersion fusible additive group. with this observational work we sought to determine if it is possible to use a waste formed during the making of foam glass to make ceramic products as well as determine what composition is most appropriate for small porous building ceramics production. performed experiments determined which burning temperature is most appropriate to make building ceramic and how burning temperature influences building ceramics properties. materials materials used in the work are clay, sand and an additive – a waste formed during the making of granulated foam glass (later pggw). the chemical composition of clay is shown in the first table. loss of clay during burning is 12 %.the used clay is attributed to light melting hydromicous clay group. it is half acidic and calcareous, since it’s contaminated with carbonated insertions, which are ≥ 3,0 %. this clay is attributed to a clay group with big amount of colouring oxygen, since it has 5,29 % iron oxide fe 2 o 3. clay’s plasticity number is 10, while linear drying shrinkage 4.9 %. according to granuliometric composition clay is the type, in which the smallest pieces’ mass, whom size is smaller than 0.001 mm, is even 51.7%. used quartz sand had 0/1 fraction, in which sio 2 takes up no less than 95%. the waste formed during granulated foam glass production is an unfit for further technological cycle granulate, its chemical composition is given in the table 2. this material is attributed to nonflammable materials, since its resistance to heat reaches 750 °c temperature. specific surface 2000-15 000 cm2/g (according to blain method). the material is light grey color powder. methods and materials table 1 chemical composition of clay, % sio 2 al 2 o 3 +tio 2 fe 2 o 3 cao+mgo k 2 o na 2 o so 3 47.1 16.5 5.3 14.1 3.6 1.2 0.2 the needed amounts of materials to make the mixture are determined by experiment planning method written by researchers (žurauskienė et al. 2009). this planning method was selected to lower the number of experiments, when during the duration of experiment three composite materials’ amounts are changed. the mixture formation compositions’ are formed using the triangular diagram. the triangular diagram shows in what materials amount zone the executed experiments were chosen (fig. 1), that area is marked red. table 2 chemical composition of pggw, % sio 2 al 2 o 3 k 2 o+na 2 o cao+mgo fe 2 o 3 other 71–73 1.5–2 13–14 8–10.5 ≤0.3 ≤0.5 fig. 1 triangular compositions selection diagram journal of sustainable architecture and civil engineering 2015/1/10 52 the lowest and highest material levels were selected: clay part in mixture 0.55-1.0, sand part in mixture 0-0.15, pggw part in mixture 0-0.3. in the experimented area five points were distinguished according to which formation mixture compositions were determined. formation mixture compositions are shown in fig. 2. sixth formation mixture composition (b) is chosen so experimentally compare properties, when the mixture has maximal amount reducing additive. fig. 2 formation masses composition samples’ production technology raw materials were dried in 100-105 °c temperature. distributed component mixture at first was mixed dryly, later moistened to right dampness for forming. the moist mass is left for three day in (95±5) % dampness environment, to allow the moister to spread equally. after three days of storage the formed masses were formed into 70×70×70 mm samples. fig. 3 samples’ burning parameters formed semi-finished products at first were dried in natural conditions for 5 days in a laboratory, afterwards 2 more days dried in an electronic dryer. in it samples were dried in 60±5 °c temperature the first day and 105±5 °c temperature the second day. samples were burned in 1000 °c, 1030 °c and 1050 °c temperatures, total longest burning duration 44 h, keeping in the highest burning temperature for 4 hours. each sample’s batch’s samples were burned changing highest burning temperature and the duration in it. samples’ burning parameters are shown in fig. 3. samples’ burning temperatures were selected according to earlier research results. with these researches the limit usable clays’ burning temperature was determined. the samples formed only of analysed clay without fractions only hold 1000 °c temperature. this temperature can be held for a longer duration, for example 4 h. with this research it was aimed to determine, what burning temperature would be appropriate to produce high density, small impregnation building ceramics. after the sample burning samples’ physical and mechanical properties were determined. research methodology building ceramics compressive strength determined according to lst en 772-1:2003, netto dry density determined according to lst en 772-13:2003, water impregnation according to lst en 771-1:2011 however samples were soaked not for 24, but 72 hours. shrinkage was calculated by this formula: 53 journal of sustainable architecture and civil engineering 2015/1/10 building ceramics effective and total open porous, as well exploited prognosis of resistance to frost determined according to (mačiulaitis and malaiškienė, 2009) method. where: l0 – distance between indentations in formed sample, mm; l1 – distance between indentations in burned sample, mm. (1)l = 100 0 10 ⋅ − l ll , % burned in 1000 °c, 1030 °c ir 1050° c temperatures forming masses with sand and pggw additive physical and mechanical properties shown in examples fig. 4–9. linear shrinkage results fig. 4 linear shrinkage of samples samples’ linear shrinkage depends on forming masses composition. putting 30 % pggw additive into the forming mass achieves the biggest linear shrinkage, which in 1050 °c temperature can reach even 19.3 % (f in fig. 4.). samples image after burning in 1050 °c temperature are shown in fig. 5. from the image, we see, that this temperature is too high for burning samples formed only from clay mixture (samples fracture burning in such temperature). samples which forming masses composition has big amount of pggw evidently shrank but also changed its own colour. mass marked with the letter c after burning became yellow, marked f – dark brown. fig. 5 samples image after burning in 1050 °c temperature density dry sample density was determined. it’s shown in fig. 6. entering into forming mass 30 % waste additive and burning in 1000 °c burning temperature building ceramics density reaches 1920 kg/m3 (fig. 6), and controlled (only clay was used for forming mass) building ceramics density – 1790 kg/m3. 30 % waste additive building ceramics density near 1000 °c burning temperature rises 7 %. by rising the burning temperature to 1030 °c building ceramics (f) density comparing with controlled building ceramics (a) rises 10 % and in 1050 °c lowers 1 %. highest density results were reached burning samples in 1050 °c temperature, and highest density value was achieved when in the forming mass were added 30 % waste and 15 % sand. obtained all group density results showed that microdispercion waste additive can significantly rise building ceramics density. products made from analyzed ceramics forming masses can be attributed to hd product group according to dry density (lst en 771–1:2011). journal of sustainable architecture and civil engineering 2015/1/10 54 water impregnation fig. 7 shows a, b, c, d, e, f group sample impregnation value after 72 h soaking, %. lowest average water impregnation after 72 h determined for f group samples – 1.0-4.4. %, formed from 70 % clay and 30 % additive. building ceramics, which had 30 % additive after burning in 1050 °c temperature maintaining in this temperature for 4 h, had the lowest impregnation, which reached only about 1 %. in this temperature building ceramics with maximal additive amount rapidly shrinks, lowering the volume of pores, and fills this volume with emerged liquid phase. highest average water impregnation after 72 h determined for a group samples 13.3 %, burned in 1000 °c temperature with maintaining it in it for 4 h. impregnation determined after 72 h of soaking are needed to calculate effective and general samples’ porous, as well as exploited prognosis of resistance to frost. analysing determined lowest impregnated sample results after 24 h soaking, it is visible that their impregnation during the remaining two days changed only 0.1 % (after 24 h these samples’ impregnation reached 0.9 %). producing small porous construction building ceramics it is important, that these ceramics impregnation would be <6 %. fig. 6 density of samples fig. 7 water impregnation of samples 55 journal of sustainable architecture and civil engineering 2015/1/10 compressive strength ceramics samples’ compressive strength averages are shown in fig. 8. according to determined compressive strength results we can see that the additive pggw positively affects building ceramics’ strength. even 15 % of additives amount quite significantly influences compressive strength results. when temperature and maintenance are higher compressive strength may lower due to micro-cracks that formed during 1050 °c temperature with 30 % additive (f). sand on the other hand reduces compressive strength. such sands influence can be explained by the fact that its particles with building ceramics don’t sinter together. sand only works as a reduced additive and at the same time reduces building ceramics shrinkage and waters need for mixing plastic ceramic mass. fig. 8 compressive strength of samples frost resistant according to determined samples’ structural indicators exploited prognosis of resistance to frost was calculated. general tendencies exploited prognosis of resistance to frost rises significantly fig. 9 frost resistant of samples journal of sustainable architecture and civil engineering 2015/1/10 56 after rising the burning temperature to 1050 °c and maintaining the samples in it for 4 h. however not all samples handle such burning temperature, for example, samples produced only from clay disintegrated from such burning temperature. samples’ exploited prognosis of resistance to frost is shown in fig. 9. the start of samples’ disintegration goes from 6 to 1580 cycles. taking into account obtained structural indicators and calculated resistance to frost prognosis values, other technological factors should be noted (forming masses composition, structures inhomogeneity), duration of burning and similar) since they also have influence on products durability prognosis. c and f samples burned in 1050 °c temperature structural purposefulness unevenness indicator is equal 1. the higher same compositions forming masses burning temperature and the more fusible additive, the lower effective and general open porous values, that’s why exploited prognosis of resistance to frost rises. as you can see, exploited prognosis of resistance to frost for group’s f samples are significantly better than other group samples’. building ceramics exploited resistance to frost really depends on pore and capillary space filling with water degree or left reserve space. all samples produced from mass f have a very big reserve of pore volume (above 50 %) as well as mass c burned in 1050 °c temperature. discussion wanting to get predetermined property ceramic products it is important to choose not only the forming mass composition, but also technological burning parameters. changing the burning temperature and the duration in highest temperature it is possible get different property products from the same forming mass. in the examined case it was predetermined to make samples with as high as possible exploited resistance to frost, which would sufficiently mechanically strong and would absorb water as less as possible. such products can be made from light melting hydromicous clay with waste additive. burning such forming masses important factors are not only the burning temperature but also the duration in it, since during the making of building ceramics in the highest temperature happens the forming of new materials, forming of structure, and closing of pores. all these procedures determine that after the burning dense sinter building ceramics are obtained. however the structures rising density is related to such phenomenon as significant ceramics shrinkage and because of these reasons precise measurement ceramic products production becomes problematic. conclusions this works results showed that the higher (from 1000 °c to 1050 °c) sample burning temperature, the higher building ceramics with granulated foam glass waste additive density. highest density value was reached in those samples that were made from 55 % clay, 15 % sand and 30 % waste additive and were burned in 1050 °c temperature with the duration of keeping it at the highest burning temperature for 4 h in the highest temperature – 2105 kg/m3. analysing research data it was determined that in the highest sample burning temperature average water impregnation and open sample porous are the lowest. the highest sample absorption was determined in that sample group in which samples were produced from 100 % clay and burned in 1000 ° c temperature with the duration of keeping it at the highest burning temperature for 4 hours, while smallest average water impregnation is in those samples’ groups in which the samples are made from 70 % clay and 30 % waste additive and burned in 1050 °c temperature with maintaining it for 4 hours. it was determined that samples with 30 % additive amount burned in 1050 °c temperature with maintaining it in the highest temperature for 4 hours, average general porous is 72 % smaller than samples, burned in 1030 °c temperature without maintenance and 76 % than samples burned near 1000 °c temperature with the duration of keeping it at the highest burning temperature for 4 hours. similar tendencies are typical for sample groups with 55 % clay, 15 % sand and 30 % waste additive amount. analysing obtained data it was determined that the higher samples’ burning temperature and the longer duration of keeping it at the highest burning temperature, the bigger compressive strength 57 journal of sustainable architecture and civil engineering 2015/1/10 and density values. also the samples with biggest waste additive, comparing with controlled samples, have higher compressive strength. it can be said, that the samples strength properties depend on burning temperature and waste additive amount. the highest prognosis for resistance to frost were determined to be samples with 30 % waste additive amount, which were burned in 1050 °c temperature with the duration of keeping it at the highest burning temperature for 4 hours. it was observed that the samples with 30 % waste additive amount prognosis for resistance to frost raised with raising burning temperature. other samples’ resistance to frost values are very different and depend on technological factors – forming mass’s composition, structures inhomogeneity, duration of burning and similar. thanks to vgtu termoinsulation science institute’s building materials laboratory for executed research and uab “stikloporas” for continual help with materials. acknowledgment referencesbinhussaina m. a., marangonib m., bernardo e., colombo p. 2014. sintered and glazed glass-ceramics from natural and waste raw materials. ceramics international. vol. 40, issue 2, 3543-3551. http://dx.doi. org/10.1016/j.ceramint.2013.09.074 kizinievič o., balkevičius v., pranckevičienė j., kizinievič v. 2014. investigation of the usage of centrifuging waste of mineral wool melt (cmww), contaminated with phenol and formaldehyde, in manufacturing of ceramic products. waste management: international journal of integrated waste management, science and technology. vol. 34 iss.8 (2014), 1488-1494. kizinievič o., žurauskienė r., kizinievič v., žurauskas r. 2013. utilisation of sludge waste from water treatment for ceramic products. construction and building materials. vol. 41, 464-473. http://dx. doi.org/10.1016/j.conbuildmat.2012.12.041 mačiulaitis r., malaiškienė j. 2009. possibilities to control ceramics properties by changing firing cycles. construction and building materials. 23 (1), 226-232. http://dx.doi.org/10.1016/j.conbuildmat.2007.12.012 lst en 771-1:2011. specification for masonry units part 1: clay masonry units. lithuania standards board, p.49. lst en 772-1:2011. methods of test for masonry units part 1: determination of compressive strength. lithuania standards board, p. 13. lst en 772-13:2003. methods of test for masonry units part 13: determination of net and gross dry density of masonry units (except for natural stone). lithuania standards board, p. 8. žurauskienė r., mačiulaitis r., yakovlev, g.i. 2009. optimal mix for building ceramics. glass and ceramics. vol. 66, no. 3-4, 86-89. http://dx.doi. org/10.1007/s10717-009-9134-6 ramunė žurauskinė assoc. prof. dr. vilnius gediminas technical university, faculty of civil engineering, department of building materials main research area structural ceramics, waste materials in production, materials science, concrete, polymeric materials address sauletekio ave. 11, lt-10223 vilnius, lithuania tel. +370 631 891 30 e-mail: ramune.zurauskiene@vgtu.lt andrius kudžma master’s degree vilnius gediminas technical university, laboratory of building products technology, scientific institute of thermal insulation main research area structural ceramics, waste materials in production address linkmenu. 28, lt-08217 vilnius, lithuania tel. +370 653 71 894 e-mail: andriuskudzma@gmail.com rimvydas žurauskas assoc. prof. dr. material users and makers association main research area polymer materials, non-autoclaved porous concrete, materials science, building ceramics, water treatment address zemynos 47-43, lt-06127 vilnius, lithuania tel. +370 699 97 381 e-mail: rzuster@gmail.com about the authors journal of sustainable architecture and civil engineering 2014/4/9 16 jsace 4/9 journal of sustainable architecture and civil engineering vol. 4 / no. 9 / 2014 pp. 16-25 doi 10.5755/j01.sace.9.4.7225 © kaunas university of technology received 2014/06/02 accepted after revision 2014/09/01 urban crime in the city of new haven: residential burglaries irina matijošaitienė* yale university macmillan center, 34 hillhouse ave., new haven, ct 06520, usa kaunas university of technology, faculty of civil engineering and architecture, department of architecture and urbanism studentu st. 48, lt-51367 kaunas, lithuania *corresponding author: irina.matijosaitiene@yale.edu; irina.matijosaitiene@ktu.edu urban crime in the city of new haven: residential burglaries http://dx.doi.org/10.5755/j01.sace.9.4.7225 introduction the research presented in this paper is based on the space syntax theory saying that pedestrian movement strongly correlates with some topological properties of urban spaces. since crime is closely related to the urban environment in which it happens it makes a sense to analyse urban crime through the prism of urban network. thus, residential burglaries committed in the city of new haven, usa, during 2009-2013 were analysed by the application of space syntax method with the combination of gis and statistical analysis (correlation and linear regression analysis). crime risk band analysis was applied for the calculation of burglary risk for each street segment. research results reveal relations between mostly all the topological properties and risk band. according to the regression analysis the further a street segment with residential dwelling is from the main routes the higher burglary risk is on that segment, and also that well-connected street segments are more vulnerable to residential burglaries. keywords: crime, gis, residential burglary, crime risk, space syntax. cities by themselves are dynamic structures with street and path network, where pedestrian movement and flows create the vitality of the whole structure. usually residential areas form the major pattern of a city. according to the previous researches (hillier and sahbaz 2005) city centers create higher crime rates in and around them due to the fact that they have more levels of activities and density. but does it mean we have to avoid streets and paths located in the city center in order to stay safe while moving from point a to point b? for example, if there is a well-used route with 200 people per hour and with 20 robberies per year, and there is a poorly used route with 20 people per hour and with 5 robberies per year, we would probably use the first route to our way home because the risk of a person being robbed is much less than on the second (poorly used) route. that is why in many cases it is more useful to analyze crime risk instead of crime rate, as crime rate in some segments of streets can be higher than on others but it doesn’t necessarily mean that in comparison with other streets’ segments this segment is more dangerous. this fact is also confirmed by o. newman (1972) who states that “some commercial street corners, identified as safe, have records, showing up to three times more crimes than any other place in the immediately surrounding urban area. however, the number of pedestrians passing any point on a commercial street is over twenty times the average of surrounding streets and areas. the rate of occurrence may be higher, but the chance of occurrence per user may be lower”. 17 journal of sustainable architecture and civil engineering 2014/4/9 in environmental criminology it is widely established that the crime is closely related to the urban environment in which it happens (tarkhanyan 2013). in environmental criminology greater attention is paid to the places where the crime was committed. as the experience on crime investigations shows criminals are most likely to commit a crime near their living place or on the paths which connect major activities places (shopping, leisure etc. places). for instance, as the results of m. lopez’s and a. van nes’s (van nes and lopez 2010) research show, “most residential burglaries took place in the most segregated and unconstituted streets that lay within a radius of 2.1 km from a burglar’s home address”. australian institute of criminology resource says that “most burglars (77%) travelled away from their home suburb to do their work, travelling an average of five kilometres to their target“ (ratcliffe 2003). these facts prove the hypothesis that the network of committed crimes’ locations is related to a certain place. understanding the relation between the place and the crime can help us analyse, forecast and predict the crime. residential burglaries in new haven city, connecticut, usa, are the object of this research. in this case only burglaries from one, two, three and four family residential houses were investigated, not taking into account burglaries from apartments. new haven is the second largest city in connecticut, with the population about 130,741 (according to census bureau data of july 1, 2012) and the area the research presented in this paper is based on the space syntax theory saying that pedestrian movement strongly correlates with some topological properties of urban spaces. since crime is closely related to the urban environment in which it happens it makes a sense to analyse urban crime through the prism of urban network. thus, residential burglaries committed in the city of new haven, usa, during 2009-2013 were analysed by the application of space syntax method with the combination of gis and statistical analysis (correlation and linear regression analysis). crime risk band analysis was applied for the calculation of burglary risk for each street segment. research results reveal relations between mostly all the topological properties and risk band. according to the regression analysis the further a street segment with residential dwelling is from the main routes the higher burglary risk is on that segment, and also that wellconnected street segments are more vulnerable to residential burglaries. keywords: crime, gis, residential burglary, crime risk, space syntax. 1. introduction cities by themselves are dynamic structures with street and path network, where pedestrian movement and flows create the vitality of the whole structure. usually residential areas form the major pattern of a city. according to the previous researches (hillier and sahbaz 2005) city centers create higher crime rates in and around them due to the fact that they have more levels of activities and density. but does it mean we have to avoid streets and paths located in the city center in order to stay safe while moving from point a to point b? for example, if there is a well-used route with 200 people per hour and with 20 robberies per year, and there is a poorly used route with 20 people per hour and with 5 robberies per year, we would probably use the first route to our way home because the risk of a person being robbed is much less than on the second (poorly used) route. that is why in many cases it is more useful to analyze crime risk instead of crime rate, as crime rate in some segments of streets can be higher than on others but it doesn’t necessarily mean that in comparison with other streets’ segments this segment is more dangerous. this fact is also confirmed by o. newman (1972) who states that “some commercial street corners, identified as safe, have records, showing up to three times more crimes than any other place in the immediately surrounding urban area. however, the number of pedestrians passing any point on a commercial street is over twenty times the average of surrounding streets and areas. the rate of occurrence may be higher, but the chance of occurrence per user may be lower”. in environmental criminology it is widely established that the crime is closely related to the urban environment in which it happens (tarkhanyan 2013). in environmental criminology greater attention is paid to the places where the crime was committed. as the experience on crime investigations shows criminals are most likely to commit a crime near their living place or on the paths which connect major activities places (shopping, leisure etc. places). for instance, as the results of m. lopez’s and a. van nes’s (van nes and lopez 2010) research show, “most residential burglaries took place in the most segregated and unconstituted streets that lay within a radius of 2.1 km from a burglar's home address”. australian institute of criminology resource says that “most burglars (77%) travelled away from their home suburb to do their work, travelling an average of five kilometres to their target“ (ratcliffe 2003). these facts prove the hypothesis that the network of committed crimes’ locations is related to a certain place. understanding the relation between the place and the crime can help us analyse, forecast and predict the crime. residential burglaries in new haven city, connecticut, usa, are the object of this research. in this case only burglaries from one, two, three and four family residential houses were investigated, not taking into account burglaries from apartments. new haven is the second largest city in connecticut, with the population about 130,741 (according to census bureau data of july 1, 2012) and the area of 52.1 km 2 . a large part of the city is built up with yale university buildings, laboratories, offices and dormitories. besides yale university, there are also some other well-known universities and colleges in new haven. the green is a park which is the heart of the city located in the downtown. it is surrounded by university campus territories, offices and banks, cafes, shops, multi-storey apartment buildings, also the main bus routes and bus stops are located here. this territory can be seen in the figure 1 as a not coloured territory in the center of the city. an interesting fact is that in 2011 new haven was ranked as fourth most dangerous city in the united states. in this paper the research is presented seeking to identify relations between residential burglaries and topological features of urban network on a macro-level. fig. 1. distribution of residential burglaries in new haven city. here green coloured territories represent residential sites, and red dots represent residential burglaries exactly on the place where they were committed 2. methods space syntax method (it is a tool for topological analysis) with the combination of geographical information systems (gis) was used for the implementation of this research. space syntax differs from other tools used for the crime analysis because it does not concentrate on the analysis of “hot spots” or particular locations where crime fig. 1 distribution of residential burglaries in new haven city. here green coloured territories represent residential sites, and red dots represent residential burglaries exactly on the place where they were committed journal of sustainable architecture and civil engineering 2014/4/9 18 of 52.1 km2. a large part of the city is built up with yale university buildings, laboratories, offices and dormitories. besides yale university, there are also some other well-known universities and colleges in new haven. the green is a park which is the heart of the city located in the downtown. it is surrounded by university campus territories, offices and banks, cafes, shops, multi-storey apartment buildings, also the main bus routes and bus stops are located here. this territory can be seen in the figure 1 as a not coloured territory in the center of the city. an interesting fact is that in 2011 new haven was ranked as fourth most dangerous city in the united states. in this paper the research is presented seeking to identify relations between residential burglaries and topological features of urban network on a macro-level. space syntax method (it is a tool for topological analysis) with the combination of geographical information systems (gis) was used for the implementation of this research. space syntax differs from other tools used for the crime analysis because it does not concentrate on the analysis of “hot spots” or particular locations where crime was committed as other tools do, but it rather analyses the whole network of streets and paths with crimes on or near them. it is proved by various researches (hillier etc. 1993; hillier and iida 2005; peponis etc. 2004; peponis etc. 1990; turner and penn 2002) that topologically based measures (integration, depth, control etc.) significantly correlate with pedestrian movement patterns (60-80% correlation between moving potentials and observed movement rates, according to b. hillier (hillier and sahbaz 2009). the gis data for the research was provided by the city of new haven, it department (maps of streets and their center lines, with sites and buildings) (city … 2014), and by the police department of the new haven (all crime types committed in new haven during the last five years in 20092013, with all crimes being geocoded) (new … 2013). the depthmap software is used for the calculation of the topological characteristics of urban spaces such as connectivity, global and local integration, global and local choice, global and local depth, as well as topological step depth from the main space in the city. the arcmap software was used to combine the calculated topological characteristics with the city map and crimes. integration is related to “to-movement” and the accessibility of spaces, it is about deciding where to go. “integration (closeness) says us how close each segment is to all others under different types of distance and at different scale. integration describes how easy it is to get to one segment from all other segments. in practical terms this would mean that pedestrians would end up to such a space more often and with less effort” (hillier and iida 2005). global integration (with a radius n) shows how accessible an axis or a segment is from all the others, id est. how it is integrated in the scale of the whole city. more integrated spaces are used more as nearby destinations than more segregated spaces. local integration shows how integrated the local area is in the relationship of its surroundings. in the studies of urban crime in different cities and neighbourhoods various radii for the analysis of the spatial structure on a local level have been taken into account: metric radius of 750 meters in the research of brazilian boroughs (reis etc. 2013), metric radius of 800 meters is used in the research of anti-social behavior crimes (drugs, dumpings, violence, graffiti, theft) in three london boroughs (friendrich et al. 2009), topological radius of 3 in the research of burglaries and robberies in london city (hillier and sahbaz 2005) as well as in the research of residential burglaries and thefts from cars in two dutch cities (van nes and lopez 2013) and in the research of robbery in a neighbourhood in recife city, brazil (monteiro and iannicelli 2009). as b. hillier (2007) states, for the local movement the radius of 800 meters is the best accounted. based on a. van nes (van nes and lopez 2013) studies of dutch neighbourhoods „angular analyses with a high metrical radius show how the area is connected to the location of the main routes in the city/town“, and „angular analyses with a low metrical radius show the spatial potentials for the vitality of a local center inside the neighbourhood“. during the research presented in this paper various topological and angular radii were tested from 3 to 10. methods 19 journal of sustainable architecture and civil engineering 2014/4/9 results choice is related to the choice of path on the way to the destination or so-called “throughmovement”. “choice (betweenness) says us how much movement is likely to pass through each segment on trips between all other segments, again using different types of distance and different radii. choice describes how likely you are to pass through the segment on trips, and so it’s potential as a route, from all segments to all others” (hillier and iida 2005). choice also may be analysed at a global (radius n) and local (2, 3 etc. radii) levels. connectivity is a local characteristic which lets us know about the direct connection of spaces. connectivity is defined as the number of nodes that connect directly to a given node (raford and ragland 2004). depth measures the social cultural integrity of the inner spaces of the downtown. depth defines the number of steps from any node to any other node (raford and ragland, 2004). for the spatial analysis of new haven and for the calculation of the topological measure segment analysis was performed and the segmental map of the city was created. according to b. hillier (hiller and iida 2005) segment analysis has the advantage over axial line analysis in being more detailed and producing better correlation with movement analysis. segment is the shortest path which uses the least number of streets (actually the least number of “interjunction” stretches of street) to get to your destination. in the angular analysis the main idea is to find the shortest path which is the one that minimises the angle between you and your destination (turner 2008). after the segment map was build it was associated with crime map. residential burglaries were analyzed considering burglary rate and burglary risk, the latter is called “primary risk band analysis” by b. hillier and o. sahbaz (2005). burglary rate was calculated by dividing the total number of burglaries on a segment by the total number of targets (in this case it is the number of residential houses) on this segment. this measure indicates the crime rate for the specific segment, and on the basis of this calculation we can identify more and less vulnerable to burglary segments. crime rates were used for the analysis of residential burglaries and robberies in some brazilian boroughs by a. t. reis and his colleagues (resi et al. 2013). however, according to b. hillier and o. sahbaz (2005) representing crime rate as an information about crime on segments will result in a wrong illusion that segments with high numbers of dwellings have lower crime rates. though, it is not necessarily may correspond with the real situation. therefore, to escape this problem b. hillier and o. sahbaz (2005) suggest to aggregate „all segments with a given number of residential units, or within a certain band of residential units, and calculating a burglary rate is for the whole group as the total number of burglaries over the total number of targets for that group“, and they use a term „primary risk band analysis“ to name this process of aggregating the segments. differently from crime rate, crime risk for the bands is calculated in this way: 1. segments with an equal number of residential units are selected and grouped into bands, 2. within these bands (for each of made bands) the total number of crimes in segments is divided by the total number of residential units in these segments. crime risk band represents calculation results for a specific band (for example, a band of street segments with five houses, or for a street segment with housing density of three houses). crime risk band analysis was used by b. hillier and o. sahbaz (2005) in their research of burglaries in london city, by a. van nes and m. lopez (2010) in their research of burglaries and thefts from cars in dutch cities and neighbourhoods. according to the above described methodology burglary rate and risk band were calculated for all segments. for the identification of the most important (having in mind mostly used) space in the city choice measures with calculated various angular and topological radii (radii from 3 to 10) were compared. it was identified that elm street segment which lays between broadway and york streets is the most important and mostly chosen route. this street segment is in the downtown of new haven connecting many important routes within and outside the city, with boutiques, bars, journal of sustainable architecture and civil engineering 2014/4/9 20 research of burglaries and thefts from cars in dutch cities and neighbourhoods. 3. results according to the above described methodology burglary rate and risk band were calculated for all segments. for the identification of the most important (having in mind mostly used) space in the city choice measures with calculated various angular and topological radii (radii from 3 to 10) were compared. it was identified that elm street segment which lays between broadway and york streets is the most important and mostly chosen route. this street segment is in the downtown of new haven connecting many important routes within and outside the city, with boutiques, bars, apartments above them, on both sides of the segment, also a grocery shop in a distance of a couple of steps on the next street segment, that definitely attract people. in this case, topological depth from this segment of elm street to all other segments was calculated. the calculated crime rate for each segment differs from 0 to 3 (fig. 2), where 68.1% of segments are with a 0 crime rate, 22.25% of segments with the crime rate 0.0010.308, 7.65% of segments with the crime rate 0.309-0.650, 1.71% of segments with the crime rate 0.651-1.500, 0.28% of segments with the crime rate 1.501-3.000. fig. 2. distribution of burglary rates all values of the calculated crime rates were divided into five groups (according to the natural breaks (jenks) with an exclusion of 0 values), and the map of less and more burgled street segments was drawn (fig. 3). fig. 3. residential burglary rates of street segments according to the method developed by b. hillier and o. sahbaz (2005) 54 bands of street segments were formed. the total number of segments is 3214. the calculated values of burglary risk band and its distribution is strongly different from calculated burglary rates and their distribution (fig. 4). calculated crime risk differs from 0 to 0.305, where 29.28% of segments are with a 0 crime risk, 0.19% of segments are with the crime risk 0.013-0.077, 45.36% of segments are with the crime risk 0.078-0.136, 18.61% of segments are with the crime risk 0.137-0.156, 6.57% of segments are with the crime risk 0.157-0.305. here we see that the most of segments (69.01%) have crime risk which is higher than the average value of 0.089, and 54.01% of segments have higher crime risk values than the median value 0.101. according to the above described facts it can be concluded that more than half of the street segments in new haven are quite vulnerable to residential burglary because their burglary risks are higher than the average and median values. fig. 4. distribution of burglary risk band the map of more and less vulnerable to residential burglary street segments in new haven was created (according to the calculated crime risk band values of each segment) (fig. 5). research of burglaries and thefts from cars in dutch cities and neighbourhoods. 3. results according to the above described methodology burglary rate and risk band were calculated for all segments. for the identification of the most important (having in mind mostly used) space in the city choice measures with calculated various angular and topological radii (radii from 3 to 10) were compared. it was identified that elm street segment which lays between broadway and york streets is the most important and mostly chosen route. this street segment is in the downtown of new haven connecting many important routes within and outside the city, with boutiques, bars, apartments above them, on both sides of the segment, also a grocery shop in a distance of a couple of steps on the next street segment, that definitely attract people. in this case, topological depth from this segment of elm street to all other segments was calculated. the calculated crime rate for each segment differs from 0 to 3 (fig. 2), where 68.1% of segments are with a 0 crime rate, 22.25% of segments with the crime rate 0.0010.308, 7.65% of segments with the crime rate 0.309-0.650, 1.71% of segments with the crime rate 0.651-1.500, 0.28% of segments with the crime rate 1.501-3.000. fig. 2. distribution of burglary rates all values of the calculated crime rates were divided into five groups (according to the natural breaks (jenks) with an exclusion of 0 values), and the map of less and more burgled street segments was drawn (fig. 3). fig. 3. residential burglary rates of street segments according to the method developed by b. hillier and o. sahbaz (2005) 54 bands of street segments were formed. the total number of segments is 3214. the calculated values of burglary risk band and its distribution is strongly different from calculated burglary rates and their distribution (fig. 4). calculated crime risk differs from 0 to 0.305, where 29.28% of segments are with a 0 crime risk, 0.19% of segments are with the crime risk 0.013-0.077, 45.36% of segments are with the crime risk 0.078-0.136, 18.61% of segments are with the crime risk 0.137-0.156, 6.57% of segments are with the crime risk 0.157-0.305. here we see that the most of segments (69.01%) have crime risk which is higher than the average value of 0.089, and 54.01% of segments have higher crime risk values than the median value 0.101. according to the above described facts it can be concluded that more than half of the street segments in new haven are quite vulnerable to residential burglary because their burglary risks are higher than the average and median values. fig. 4. distribution of burglary risk band the map of more and less vulnerable to residential burglary street segments in new haven was created (according to the calculated crime risk band values of each segment) (fig. 5). research of burglaries and thefts from cars in dutch cities and neighbourhoods. 3. results according to the above described methodology burglary rate and risk band were calculated for all segments. for the identification of the most important (having in mind mostly used) space in the city choice measures with calculated various angular and topological radii (radii from 3 to 10) were compared. it was identified that elm street segment which lays between broadway and york streets is the most important and mostly chosen route. this street segment is in the downtown of new haven connecting many important routes within and outside the city, with boutiques, bars, apartments above them, on both sides of the segment, also a grocery shop in a distance of a couple of steps on the next street segment, that definitely attract people. in this case, topological depth from this segment of elm street to all other segments was calculated. the calculated crime rate for each segment differs from 0 to 3 (fig. 2), where 68.1% of segments are with a 0 crime rate, 22.25% of segments with the crime rate 0.0010.308, 7.65% of segments with the crime rate 0.309-0.650, 1.71% of segments with the crime rate 0.651-1.500, 0.28% of segments with the crime rate 1.501-3.000. fig. 2. distribution of burglary rates all values of the calculated crime rates were divided into five groups (according to the natural breaks (jenks) with an exclusion of 0 values), and the map of less and more burgled street segments was drawn (fig. 3). fig. 3. residential burglary rates of street segments according to the method developed by b. hillier and o. sahbaz (2005) 54 bands of street segments were formed. the total number of segments is 3214. the calculated values of burglary risk band and its distribution is strongly different from calculated burglary rates and their distribution (fig. 4). calculated crime risk differs from 0 to 0.305, where 29.28% of segments are with a 0 crime risk, 0.19% of segments are with the crime risk 0.013-0.077, 45.36% of segments are with the crime risk 0.078-0.136, 18.61% of segments are with the crime risk 0.137-0.156, 6.57% of segments are with the crime risk 0.157-0.305. here we see that the most of segments (69.01%) have crime risk which is higher than the average value of 0.089, and 54.01% of segments have higher crime risk values than the median value 0.101. according to the above described facts it can be concluded that more than half of the street segments in new haven are quite vulnerable to residential burglary because their burglary risks are higher than the average and median values. fig. 4. distribution of burglary risk band the map of more and less vulnerable to residential burglary street segments in new haven was created (according to the calculated crime risk band values of each segment) (fig. 5). fig. 2 distribution of burglary rates fig. 3 residential burglary rates of street segments fig. 4 distribution of burglary risk band apartments above them, on both sides of the segment, also a grocery shop in a distance of a couple of steps on the next street segment, that definitely attract people. in this case, topological depth from this segment of elm street to all other segments was calculated. the calculated crime rate for each segment differs from 0 to 3 (fig. 2), where 68.1% of segments are with a 0 crime rate, 22.25% of segments with the crime rate 0.001-0.308, 7.65% of segments with the crime rate 0.309-0.650, 1.71% of segments with the crime rate 0.651-1.500, 0.28% of segments with the crime rate 1.501-3.000. all values of the calculated crime rates were divided into five groups (according to the natural breaks (jenks) with an exclusion of 0 values), and the map of less and more burgled street segments was drawn (fig. 3). according to the method developed by b. hillier and o. sahbaz (2005) 54 bands of street segments were formed. the total number of segments is 3214. the calculated values of burglary risk band and its distribution is strongly different from calculated burglary rates and their distribution (fig. 4). calculated crime risk differs from 0 to 0.305, where 29.28% of segments are with a 0 crime risk, 0.19% of segments are with the crime risk 0.013-0.077, 45.36% of segments are with the crime risk 0.078-0.136, 18.61% of segments are with the crime risk 0.137-0.156, 6.57% of segments are with the crime risk 0.157-0.305. here we see that the most of segments (69.01%) have crime risk which is higher than the average value of 0.089, and 54.01% of segments have higher crime risk values than the median value 0.101. according to the above described facts it can be concluded that more than half of the street segments in new haven are quite vulnerable to residential 21 journal of sustainable architecture and civil engineering 2014/4/9 fig. 5. street segments’ vulnerability to residential burglary based on crime risk bank analysis according to the crime risk band analysis the most vulnerable to residential burglary are street segments with 41 (with crime risk 0.305), 44 (with crime risk 0.25) and 32 (with crime risk 0.241) residential dwellings. though, it does not mean that high crime risk is statistically related to the above mentioned numbers of segments. moreover, figure 5 clearly demonstrates a strong relation between calculated residential burglary rate and the number of residential dwellings, in contrast to burglary risk band (fig. 6) which is not related to the number of residential dwellings on segments. that means, that further analysis of crime rate may lead to wrong interpretation of the results, because it shows that the less residential dwellings are on a segment the higher burglary rate is on that segment. therefore, crime risk band values are used for the statistical analysis. fig. 6. relation between burglary rate and the number of residential dwelling on a segment (picture above), and relation between burglary risk band and the number of residential dwelling on a segment (picture below) all calculated topological measures of the new haven city as well as crime risk band were used for the statistical analysis. pearson correlation analysis demonstrates relations between mostly all the topological properties and risk band. smaller correlations are observed for the depth, choice and integration with topological radii in comparison with the angular radii. linear regression analysis discovered that there was a significant relation between burglary risk band and local depth at a topological radius 3 (r 2 =0.1, p=0.000<α=0.05), that means that the further a street segment with residential dwelling is from the main routes the higher burglary risk is on that segment. the visual analysis of the depth r3 step map layered by the locations of residential burglaries (fig. 7) makes it obvious that the major part of the burglaries are located on deeper street segments (blue and dark blue coloured). that proves the fact that at the local level deeper street segments generate higher crime risk for residential dwellings. also there is a significant relation between burglary risk band and connectivity (r 2 =0.3, p=0.000<α=0.05). after comparing these results with the connectivity map layered by the locations of residential burglaries (fig. 8) it becomes obvious that more vulnerable to residential burglaries street segments are those that are well connected. for instance, if a street segment connects by its ends with 6 or 5 or 4 other segments it will definitely be more attractive for a burglar, than a street segment that connects with 1 or 2 other segments. here also another evidence can be applied: wellconnected streets might attract more pedestrian movements because they connect to more other segments. together with regular pedestrians they may attract burglars as well. there are also significant though very weak positive relations between residential burglary risk band and segment length, significant though very weak negative relations between residential burglary risk band depth r4.00 (angular), depth r10 (topological), and global choice. that could mean that the longer a street segment is the higher burglary risk is on it. and the less a segment is chosen to pass on the way to other segments (“through-movement”) the higher burglary risk is on that segment. according to the regression model and to the coefficients table, it can be according to the above described facts it can be concluded that more than half of the street segments in new haven are quite vulnerable to residential burglary because their burglary risks are higher than the average and median values. fig. 4. distribution of burglary risk band the map of more and less vulnerable to residential burglary street segments in new haven was created (according to the calculated crime risk band values of each segment) (fig. 5). fig. 5. street segments’ vulnerability to residential burglary based on crime risk bank analysis according to the crime risk band analysis the most vulnerable to residential burglary are street segments with 41 (with crime risk 0.305), 44 (with crime risk 0.25) and 32 (with crime risk 0.241) residential dwellings. though, it does not mean that high crime risk is statistically related to the above mentioned numbers of segments. moreover, figure 5 clearly demonstrates a strong relation between calculated residential burglary rate and the number of residential dwellings, in contrast to burglary risk band (fig. 6) which is not related to the number of residential dwellings on segments. that means, that further analysis of crime rate may lead to wrong interpretation of the results, because it shows that the less residential dwellings are on a segment the higher burglary rate is on that segment. therefore, crime risk band values are used for the statistical analysis. fig. 6. relation between burglary rate and the number of residential dwelling on a segment (picture above), and relation between burglary risk band and the number of residential dwelling on a segment (picture below) all calculated topological measures of the new haven city as well as crime risk band were used for the statistical analysis. pearson correlation analysis demonstrates relations between mostly all the topological properties and risk band. smaller correlations are observed for the depth, choice and integration with topological radii in comparison with the angular radii. linear regression analysis discovered that there was a significant relation between burglary risk band and local depth at a topological radius 3 (r 2 =0.1, p=0.000<α=0.05), that means that the further a street segment with residential dwelling is from the main routes the higher burglary risk is on that segment. the visual analysis of the depth r3 step map layered by the locations of residential burglaries (fig. 7) makes it obvious that the major part of the burglaries are located on deeper street segments (blue and dark blue coloured). that proves the fact that at the local level deeper street segments generate higher crime risk for residential dwellings. also there is a significant relation between burglary risk band and connectivity (r 2 =0.3, p=0.000<α=0.05). after fig. 5 street segments’ vulnerability to residential burglary based on crime risk bank analysis fig. 6 relation between burglary rate and the number of residential dwelling on a segment (picture above), and relation between burglary risk band and the number of residential dwelling on a segment (picture below) burglary because their burglary risks are higher than the average and median values. the map of more and less vulnerable to residential burglary street segments in new haven was created (according to the calculated crime risk band values of each segment) (fig. 5). according to the crime risk band analysis the most vulnerable to residential burglary are street segments with 41 (with crime risk 0.305), 44 (with crime risk 0.25) and 32 (with crime risk 0.241) residential dwellings. though, it does not mean that high crime risk is statistically related to the above mentioned numbers of segments. moreover, figure 5 clearly demonstrates a strong relation between calculated residential burglary rate and the number of residential dwellings, in contrast to burglary risk band (fig. 6) which is not related to the number of residential dwellings on segments. that means, that further analysis of crime rate may lead to wrong interpretation of the results, because it shows that the less residential dwellings are on a segment the higher burglary rate is on that segment. therefore, crime risk band values are used for the statistical analysis. all calculated topological measures of the new haven city as well as crime risk band were used for the statistical analysis. pearson correlation analysis demonstrates relations between mostly all the topological properties and risk band. smaller correlations are observed for the depth, choice and integration with topological radii in comparison with the angular radii. linear regression analysis discovered that there was a significant relation between burglary risk band and local depth at a topological radius 3 (r2=0.1, p=0.000<α=0.05), that means that the further a street segment with journal of sustainable architecture and civil engineering 2014/4/9 22 residential dwelling is from the main routes the higher burglary risk is on that segment. the visual analysis of the depth r3 step map layered by the locations of residential burglaries (fig. 7) makes it obvious that the major part of the burglaries are located on deeper street segments (blue and dark blue coloured). that proves the fact that at the local level deeper street segments generate higher crime risk for residential dwellings. also there is a significant relation between burglary risk band and connectivity (r2=0.3, p=0.000<α=0.05). after comparing these results with the connectivity map layered by the locations of residential burglaries (fig. 8) it becomes obvious that more vulnerable to residential burglaries street segments are those that are well connected. for instance, if a street segment connects by its ends with 6 or 5 or 4 other segments it will definitely be more attractive for a burglar, than a street segment that connects with 1 or 2 other segments. here also another evidence can be applied: wellconnected streets might attract more pedestrian movements because they connect to more other segments. together with regular pedestrians they may attract burglars as well. there are also significant though very weak positive relations between residential burglary risk band and segment length, significant though very weak negative relations between residential burglary risk band depth r4.00 (angular), depth r10 stated with an assurance of 95% that with the increase of street segment connectivity by 1 conditional unit the burglary risk will increase by 0.1-0.5 units, and with the increase of street segment depth r3 step by 1 conditional unit the burglary risk will increase by 0.1. though, a rather large constant 1.05 does not explain the dispersion of all the variables that is why the remaining part of the factors determining the burglary risk remains unknown for us. that is to say, that street segments that are further from the main routes, less connected, longer and less used on the way to the destination are more vulnerable to residential burglary. fig. 7. depth r3 step map with locations of residential burglaries. here cold colours (dark blue, blue and green) mean deep street segments, warm colours (red, orange, yellow) mean shallow street segments. black dots are residential burglaries fig. 8. connectivity map with locations of residential burglaries. here cold colours (dark blue=1, blue=2 and green=3) mean weakly-connected street segments, warm colours (red=6, orange=5, yellow=4) mean well-connected street segments. black dots are residential burglaries 4. discussion this research provides new insights into how crime may be analysed through the topological properties of urban spaces. the case of new haven city demonstrates that deep at the local scale urban spaces and poorly connected spaces generate higher risks for residential dwellings located on these spaces to be burgled. comparing these results with the ones from the research of dutch cities alkmaar and gouda (van nes and lopez 2010) we see that in dutch cities there are correlations between burglary risk and topological depth, risk and constitutedness, risk and local integration. in the analysis of new haven constitutedness was not taken into account due to not enough time for it (it is supposed to be a subject for the further research). pearson correlation in the case of new haven demonstrated relations between local (with angular radii) and global integration and risk band. also in both dutch cities and new haven mostly all topological properties correlate with risk band. in the research of burglaries in london city (hillier and sahbaz 2005) they discovered that streets segments with 1-2 connected segments (low connectivity value) have the lowest average burglary rates. for b. hillier and o. sahbaz this finding was unexpected and shocking. they commented about that: “it is striking that the greater connectivity in the street pattern itself is associated with less, rather than more burglary” (hillier and sahbaz 2005). in the research of new haven it is opposite: street segments with higher connectivity values are more vulnerable to burglaries, what is likely to be the result that b. hillier and o. sahbaz were suspected to get in their research. in their research of london more burglaries were committed on longer street segments, the same is observed in new haven. this fact about the positive relation between segment length and burglary risk also coordinates with the fact about positive correlation between connectivity and risk, because according to many researchers street length is strongly related to connectivity. in london burglaries more occur on locally and globally (r15) integrated segments. pearson correlation in new haven case also shows relations between local and global integration and burglary risk. due to a large constant 1.05 in the regression model that expresses independent variables influencing burglary risk, there is a need to extend the research on a micro-level, taking into account such factors as building centered density, dwelling and street types, constitutedness, land use, street form, intervisibility, step depth from house entrance to the street segment, greenery, lighting and various factors of surrounding environment. that is the aim of future research. 5. conclusions analysis and comparison of the calculated burglary rates and burglary risks led us to the decision to use burglary risk for the macro-scale analysis because burglary rates show nothing more except increase the rates with the decrease of the number of targets, id est. the number of residential dwellings. pearson correlation analysis demonstrates relations between mostly all the topological properties and risk band. smaller correlations are observed for the depth, choice and stated with an assurance of 95% that with the increase of street segment connectivity by 1 conditional unit the burglary risk will increase by 0.1-0.5 units, and with the increase of street segment depth r3 step by 1 conditional unit the burglary risk will increase by 0.1. though, a rather large constant 1.05 does not explain the dispersion of all the variables that is why the remaining part of the factors determining the burglary risk remains unknown for us. that is to say, that street segments that are further from the main routes, less connected, longer and less used on the way to the destination are more vulnerable to residential burglary. fig. 7. depth r3 step map with locations of residential burglaries. here cold colours (dark blue, blue and green) mean deep street segments, warm colours (red, orange, yellow) mean shallow street segments. black dots are residential burglaries fig. 8. connectivity map with locations of residential burglaries. here cold colours (dark blue=1, blue=2 and green=3) mean weakly-connected street segments, warm colours (red=6, orange=5, yellow=4) mean well-connected street segments. black dots are residential burglaries 4. discussion this research provides new insights into how crime may be analysed through the topological properties of urban spaces. the case of new haven city demonstrates that deep at the local scale urban spaces and poorly connected spaces generate higher risks for residential dwellings located on these spaces to be burgled. comparing these results with the ones from the research of dutch cities alkmaar and gouda (van nes and lopez 2010) we see that in dutch cities there are correlations between burglary risk and topological depth, risk and constitutedness, risk and local integration. in the analysis of new haven constitutedness was not taken into account due to not enough time for it (it is supposed to be a subject for the further research). pearson correlation in the case of new haven demonstrated relations between local (with angular radii) and global integration and risk band. also in both dutch cities and new haven mostly all topological properties correlate with risk band. in the research of burglaries in london city (hillier and sahbaz 2005) they discovered that streets segments with 1-2 connected segments (low connectivity value) have the lowest average burglary rates. for b. hillier and o. sahbaz this finding was unexpected and shocking. they commented about that: “it is striking that the greater connectivity in the street pattern itself is associated with less, rather than more burglary” (hillier and sahbaz 2005). in the research of new haven it is opposite: street segments with higher connectivity values are more vulnerable to burglaries, what is likely to be the result that b. hillier and o. sahbaz were suspected to get in their research. in their research of london more burglaries were committed on longer street segments, the same is observed in new haven. this fact about the positive relation between segment length and burglary risk also coordinates with the fact about positive correlation between connectivity and risk, because according to many researchers street length is strongly related to connectivity. in london burglaries more occur on locally and globally (r15) integrated segments. pearson correlation in new haven case also shows relations between local and global integration and burglary risk. due to a large constant 1.05 in the regression model that expresses independent variables influencing burglary risk, there is a need to extend the research on a micro-level, taking into account such factors as building centered density, dwelling and street types, constitutedness, land use, street form, intervisibility, step depth from house entrance to the street segment, greenery, lighting and various factors of surrounding environment. that is the aim of future research. 5. conclusions analysis and comparison of the calculated burglary rates and burglary risks led us to the decision to use burglary risk for the macro-scale analysis because burglary rates show nothing more except increase the rates with the decrease of the number of targets, id est. the number of residential dwellings. pearson correlation analysis demonstrates relations between mostly all the topological properties and risk band. smaller correlations are observed for the depth, choice and fig. 7 depth r3 step map with locations of residential burglaries. here cold colours (dark blue, blue and green) mean deep street segments, warm colours (red, orange, yellow) mean shallow street segments. black dots are residential burglaries fig. 8 connectivity map with locations of residential burglaries. here cold colours (dark blue=1, blue=2 and green=3) mean weakly-connected street segments, warm colours (red=6, orange=5, yellow=4) mean well-connected street segments. black dots are residential burglaries (topological), and global choice. that could mean that the longer a street segment is the higher burglary risk is on it. and the less a segment is chosen to pass on the way to other segments (“through-movement”) the higher burglary risk is on that segment. according to the regression model and to the coefficients table, it can be stated with an assurance of 95% that with the increase of street segment connectivity by 1 conditional unit the burglary risk will increase by 0.10.5 units, and with the increase of street segment depth r3 step by 1 conditional unit the burglary risk will increase by 0.1. though, a rather large constant 1.05 does not explain the dispersion of all the variables that is why the remaining part of the factors determining the burglary risk 23 journal of sustainable architecture and civil engineering 2014/4/9 discussion remains unknown for us. that is to say, that street segments that are further from the main routes, less connected, longer and less used on the way to the destination are more vulnerable to residential burglary. this research provides new insights into how crime may be analysed through the topological properties of urban spaces. the case of new haven city demonstrates that deep at the local scale urban spaces and poorly connected spaces generate higher risks for residential dwellings located on these spaces to be burgled. comparing these results with the ones from the research of dutch cities alkmaar and gouda (van nes and lopez 2010) we see that in dutch cities there are correlations between burglary risk and topological depth, risk and constitutedness, risk and local integration. in the analysis of new haven constitutedness was not taken into account due to not enough time for it (it is supposed to be a subject for the further research). pearson correlation in the case of new haven demonstrated relations between local (with angular radii) and global integration and risk band. also in both dutch cities and new haven mostly all topological properties correlate with risk band. in the research of burglaries in london city (hillier and sahbaz 2005) they discovered that streets segments with 1-2 connected segments (low connectivity value) have the lowest average burglary rates. for b. hillier and o. sahbaz this finding was unexpected and shocking. they commented about that: “it is striking that the greater connectivity in the street pattern itself is associated with less, rather than more burglary” (hillier and sahbaz 2005). in the research of new haven it is opposite: street segments with higher connectivity values are more vulnerable to burglaries, what is likely to be the result that b. hillier and o. sahbaz were suspected to get in their research. in their research of london more burglaries were committed on longer street segments, the same is observed in new haven. this fact about the positive relation between segment length and burglary risk also coordinates with the fact about positive correlation between connectivity and risk, because according to many researchers street length is strongly related to connectivity. in london burglaries more occur on locally and globally (r15) integrated segments. pearson correlation in new haven case also shows relations between local and global integration and burglary risk. due to a large constant 1.05 in the regression model that expresses independent variables influencing burglary risk, there is a need to extend the research on a micro-level, taking into account such factors as building centered density, dwelling and street types, constitutedness, land use, street form, intervisibility, step depth from house entrance to the street segment, greenery, lighting and various factors of surrounding environment. that is the aim of future research. conclusions analysis and comparison of the calculated burglary rates and burglary risks led us to the decision to use burglary risk for the macro-scale analysis because burglary rates show nothing more except increase the rates with the decrease of the number of targets, id est. the number of residential dwellings. pearson correlation analysis demonstrates relations between mostly all the topological properties and risk band. smaller correlations are observed for the depth, choice and integration with topological radii in comparison with the angular radii. linear regression analysis discovered that there was a significant relation between burglary risk band and local depth at a topological radius 3 (r2=0.1, p=0.000<α=0.05), that means that the further a street segment with residential dwelling is from the main routes the higher burglary risk is on that segment. also there is a significant relation between burglary risk band and connectivity (r2=0.3, p=0.000<α=0.05). that means that more vulnerable to residential burglaries street segments are those that are well connected. there are also significant though very weak positive relations between residential burglary risk band and segment length, significant though very weak negative relations between residential burglary risk band depth r4.00 (angular), depth r10 (topological), and global choice. journal of sustainable architecture and civil engineering 2014/4/9 24 acknowledgment the results of this research are very similar to the results that were got in dutch cities and london city. though, concerning a high constant in the regression model the research need to be conducted at the micro-level in order to identify more factors that influence burglary risk on the street segments of new haven. the author is grateful to j.p.kazickas fund which supported with fellowship for this postdoctoral research, the baltic studies at the macmillan center at yale university for organizing the appointment as a j.p.kazickas research fellow, to the it department of the city of new haven for providing the gis data, to the police department of the new haven for providing the geocoded data about crime, and to stacey maples for the support with arcmap. references city of new haven, it department. 2014. gis data. friendrich e., hiller b., chiaradia a. 2009. anti-social behavior and urban configuration. in: proceedings of the 7th international space syntax symposium, stockholm, sweden, 034:1-034:16. hillier b., sahbaz o. 2009. crime and urban design: an 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d e p t h m a p / d o c u m e n t s / advanceddepthmap.pdf (accessed 14 april 2014). 25 journal of sustainable architecture and civil engineering 2014/4/9 irina matijošaitienė assoc. professor yale university, macmillan center, visiting scholar, and kaunas university of technology, faculty of civil engineering and architecture, department of architecture and land management main research area main research area: urban and road landscape, space syntax, kansei engineering, hedonomics, ergonomics, statistics address 34 hillhouse ave., new haven, ct 06520, usa, and studentu st. 48, lt-51367 kaunas, lithuania tel.: +1 347 515 5449, +370 37 300456 e-mail: irivarl@yahoo.com, irina.matijosaitiene@ktu.lt, irina.matijosaitiene@yale.edu about the author turner a., penn a. 2002. encoding natural movement as an agent-based system: an investigation into human pedestrian behavior in the bult environment. environment and planning b: environment and design, 29, 473-490. van nes a., lopez m. 2013. spatial-socio classification of deprived neighbourhoods in the netherlands: strategies for neighbourhood revitalisation. in: proceedings of the ninth international space syntax symposium, seoul, korea. 2013, 122:1-122:14. van nes a., lopez m.j.j. 2010. macro and micro scale spatial variables and the distribution of residential burglaries and theft from cars. journal of space syntax, 2010, 1(2), 296-314.